MESOSCALE DISCUSSION NWS STORM PREDICTION CENTER NORMAN OK

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   MESOSCALE DISCUSSION 2564
   NWS STORM PREDICTION CENTER NORMAN OK
   0944 PM CST WED DEC 14 2005
   
   AREAS AFFECTED...NRN GA / NWRN SC / WRN NC /  WRN VA
   
   CONCERNING...FREEZING RAIN
   
   VALID 150344Z - 150945Z
   
   FREEZING RAIN WITH HOURLY RATES APPROACHING 0.10 TO 0.15 INCH IS
   EXPECTED TO DEVELOP ACROSS NRN GA/NWRN SC AND SPREAD NEWD ACROSS WRN
   PORTIONS OF NC AND VA BY 15/12Z.
   
   00Z UPPER-AIR OBSERVATIONS INDICATE THAT FORCING ASSOCIATED WITH A
   COUPLED UPPER JET STRUCTURE AND LOW-LEVEL WAA ARE THE PRIMARY
   PROCESSES DRIVING LARGE PRECIPITATION SHIELD CURRENTLY OVER THE
   LOWER MS VALLEY INTO THE CNTRL GULF STATES AND TN VALLEY.  ERN EDGE
   OF THIS PRECIPITATION SHIELD IS RAPIDLY EXPANDING NEWD ACROSS NRN GA
   WHERE SURFACE WET BULB TEMPERATURES ARE SUB-FREEZING.  00Z FFC
   SOUNDING SHOWS THAT LITTLE SATURATION IS NEEDED AROUND 850 MB TO
   SATURATE VERTICAL PROFILE AND GIVEN CURRENT OBSERVATIONS THIS HAS
   ALREADY OCCURRED.
   
   DEEP-LAYER FORCING FOR ASCENT...PRIMARILY FROM THE TWO
   AFOREMENTIONED PROCESSES...IS FORECAST TO DEVELOP ENEWD
   OVERNIGHT...SUSTAINING ONGOING PRECIPITATION SHIELD ACROSS THE
   CNTRL/SRN APPALACHIANS AND ADJACENT PIEDMONT REGION.  STRONG
   LOW-LEVEL WAA ATOP SURFACE WEDGE FRONTAL ZONE IN IMMEDIATE LEE OF
   THE APPALACHIANS WILL RESULT IN A QUITE FAVORABLE VERTICAL THERMAL
   STRATIFICATION FOR FREEZING RAIN WITH A 3-4 C WARM NOSE DEVELOPING
   AROUND 850 MB.
   
   ..MEAD.. 12/15/2005
   
   
   ATTN...WFO...LWX...RAH...RNK...CAE...GSP...MRX...FFC...
   
   34368457 35818251 36778111 37558040 38097928 37167871
   35897945 34458154 33818322 33588420

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MESOSCALE DISCUSSION 2567
NWS STORM PREDICTION CENTER NORMAN OK
0626 AM CST THU DEC 15 2005

AREAS AFFECTED...NRN GA/CAROLINA PIEDMONT/CNTRL VA/ERN WV

CONCERNING...FREEZING RAIN

VALID 151226Z - 151830Z



...SIGNIFICANT FREEZING RAIN EVENT IS ONGOING THIS MORNING FROM NE
GA INTO THE CAROLINA PIEDMONT. MODERATE RATES OF FZRA UP TO 0.10
INCHES PER HOUR WILL LIKELY CONTINUE THROUGH THE MORNING...

LATEST SFC ANALYSIS SHOWS SFC LOW IN SRN AL WITH WARM/COASTAL FRONT
EXTENDING SEWD ACROSS NRN FL AND THEN CLOSELY HUGGING THE CAROLINA
COASTS. WEDGE OF SUBFREEZING AIR EXTENDS FROM NEAR ATLANTA NEWD
ACROSS THE PIEDMONT INTO ERN WV/VA. STRONG ASCENT WILL CONTINUE
AHEAD OF UPPER IMPULSE NOW OVER THE LOWER MS VALLEY. THIS LARGE
SCALE LIFT COMBINED WITH SIGNIFICANT LOW LEVEL WARM ADVECTION /VAD
WIND DATA 50-60KT AT 850MB/ WILL MAINTAIN LARGE PRECIPITATION
SHIELD. MUCH OF THE PRECIPITATION WILL BE FREEZING RAIN WITHIN THE
COLD AIR DAMMING REGION EAST OF THE MTNS.

SFC LOW PRESSURE WILL MOVE INTO WRN PORTIONS OF GA LATER THIS
MORNING AS COASTAL/WARM FRONT MOVES INLAND. BASED ON CURRENT
TRENDS...HEAVIEST AXIS OF FREEZING RAIN OVER THE NEXT FEW HOURS WILL
EXTEND FROM ATHENS TO CHARLOTTE TO EAST OF ROANOKE. RAINFALL
ACCUMULATIONS OF 0.20-0.30 INCHES HAVE BEEN OBSERVED IN NRN GA
WITHIN THE LAST 3-6 HOURS...SO SIGNIFICANT ICING ACCUMULATIONS ARE
LIKELY IN SOME AREAS.

12Z SOUNDINGS FROM RNK/GSO SHOW STRONG WAA PROFILE WITH SHALLOW WARM
LAYERS NEAR OR ABOVE 0 DEG C. WARM NOSE IS MORE PRONOUNCED AND
DEEPER AT GSO...WHICH SUPPORTS A PROLONGED PERIOD OF FZRA. A MIX OF
SLEET/SNOW WILL OCCUR IN THE HIGHER ELEVATIONS.

..TAYLOR.. 12/15/2005

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MESOSCALE DISCUSSION 2569
NWS STORM PREDICTION CENTER NORMAN OK
1000 AM CST THU DEC 15 2005

AREAS AFFECTED...NE INDIANA/SE MI/NW OH

CONCERNING...HEAVY SNOW

VALID 151600Z - 152000Z



SNOW IS EXPECTED TO INCREASE THROUGH EARLY AFTERNOON FROM FAR NE
INDIANA/NW OH INTO SE/THUMB OF MI. SNOW RATES WILL REACH 1 IN/HR ON
A LOCALIZED BASIS.

EAST OF STACKED LOW CENTERED ALONG THE MN/WI BORDER...OBSERVATIONAL
TRENDS FEATURE AXIS OF INCREASING SNOW ACROSS NE INDIANA/WRN OH/FAR
SE MI...PART OF BROADER BAROCLINIC LEAF STRUCTURE SEEN IN WATER
VAPOR/INFRARED IMAGERY. THIS ACTIVITY IS FOCUSED IN GENERAL SSW-NNE
ORIENTATION ALIGNED WITH MID LEVEL FRONTOGENETICAL FORCING BETWEEN
600-700 MB. SIMILAR TO OBSERVATIONAL TRENDS...09Z SREF AND LATEST
RUC/WRF GUIDANCE SUGGESTS SNOW SHOULD CONTINUE TO INCREASE FROM FAR
NE INDIANA/NW OH INTO SOUTHEAST/THUMB VICINITY OF MI THROUGH EARLY
AFTERNOON. ALTHOUGH LOW LEVEL TEMPERATURES PROFILES ARE
MARGINAL...AMPLE PRECIPITATION RATES SHOULD BE SUPPORTIVE OF
MDT/OCNLY HEAVY WET SNOW. SNOW RATES MAY REACH 1 IN/HR ON A
LOCALIZED BASIS INTO MID AFTERNOON.

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MESOSCALE DISCUSSION 2572
NWS STORM PREDICTION CENTER NORMAN OK
1243 PM CST THU DEC 15 2005

AREAS AFFECTED...MUCH OF PA/FAR SRN NY/WRN AND CNTRL MD/ERN WV/WRN
VA/WRN NC

CONCERNING...WINTER MIXED PRECIPITATION

VALID 151843Z - 152345Z



PREDOMINANT FREEZING RAIN/SLEET IS EXPECTED THIS AFTERNOON FROM FAR
NE OH INTO WRN/SCNTRL PA AND WRN/CNTRL MD. PRECIPITATION RATES
SHOULD INCREASE ACROSS CNTRL/ERN PA THROUGH 21Z-0ZZ...WITH SNOW
PREDOMINANT PRECIP TYPE. FURTHER SOUTH...FREEZING RAIN WILL CONTINUE
FOR THE NEXT SEVERAL HOURS ALONG THE SPINE OF THE CNTRL
APPALACHIANS...WITH A GRADUAL CHANGE OVER TO ALL RAIN OCCURRING FROM
SOUTH TO NORTH THIS AFTERNOON.

EXTENSIVE PRECIPITATION SHIELD WILL CONTINUE TO SPREAD E/NE FROM THE
OHIO VALLEY/MID ATLANTIC INTO THE NE STATES THIS
AFTERNOON...ATTRIBUTABLE TO AMPLE UVVS VIA JUXTAPOSITION OF
DPVA/UPPER JET ENHANCED LIFT AND LOW LEVEL WAA/MOISTURE TRANSPORT
REGIME.

IN ACCORDANCE WITH OBSERVATIONAL TRENDS...15Z RUC SOUNDINGS AND 09Z
SREF CONSENSUS/WINTER ALGORITHMS SUGGEST RELATIVELY LONGEST
DURATION/GREATEST PROBABILITY FOR FREEZING RAIN AND/OR SLEET THROUGH
21Z-00Z SHOULD OCCUR ACROSS WRN/SCNTRL PA...WRN/CNTRL MD...AND ERN
WV/NW VA. IN THESE AREAS...ENCROACHING 800-850 MB LEVEL WARM LAYER
/AS SAMPLED BY 12Z ROANOKE RAOB/ WILL BE FAVORABLE FOR FREEZING RAIN
AND/OR SLEET WHERE SUB-FREEZING NEAR-SFC TEMPS ARE
MAINTAINED...WHICH IS ESPECIALLY LIKELY IN VALLEY AREAS.

WITH SOUTHWARD EXTENT...OWING TO STRONG WARM AIR ADVECTION
REGIME...INITIAL COLD WEDGE WILL GRADUALLY BE OVERCOME ALONG/EAST OF
THE CNTRL APPALACHIANS THROUGH THE AFTERNOON. PREDOMINANT
PRECIP-TYPE IS EXPECTED TO GRADUALLY CHANGE FROM FREEZING RAIN TO
RAIN ACCORDINGLY FROM SOUTH TO NORTH ACROSS THE NW NC/VA
APPALACHIANS.

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MESOSCALE DISCUSSION 2573
NWS STORM PREDICTION CENTER NORMAN OK
0123 PM CST THU DEC 15 2005

AREAS AFFECTED...NE LOWER MI

CONCERNING...PRECIPITATION TRENDS...WINTER PRECIPITATION

VALID 151923Z - 152300Z



OCNLY MODERATE SNOW WILL DEVELOP/SPREAD FROM THE THUMB AREA INTO NE
LOWER MI THROUGH MID AFTERNOON. RATES COULD REACH 1 IN/HR WITHIN THE
HEAVIER BANDS FOR A FEW HOURS DURATION BETWEEN 20Z-00Z.

VOLUMETRIC RADAR TRENDS SUGGESTS AREAS OF MODERATE SNOW...ONGOING
EARLY THIS AFTERNOON ACROSS SE LOWER MI...SHOULD CONTINUE TO SPREAD
N/NE INTO THE NE PORTION OF LOWER MI REMAINDER OF THE AFTERNOON.
SIMILAR TO OBSERVATIONAL TRENDS...SHORT-TERM RUC/4KM WRF GUIDANCE
SUGGESTS THIS WILL GENERALLY OCCUR IN AREAS ALONG/EAST OF INTERSTATE
75. ATTRIBUTABLE TO AMPLE UVVS/SATURATED FAVORABLE DENDRITIC GROWTH
ZONE PER 18Z RUC SOUNDINGS...SNOW RATES COULD LOCALLY REACH 1 IN/HR
FOR A COUPLE HOURS DURATION.

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   MESOSCALE DISCUSSION 2575
   NWS STORM PREDICTION CENTER NORMAN OK
   0718 PM CST THU DEC 15 2005
   
   AREAS AFFECTED...SRN AND CNTRL NY/MUCH OF PA/WRN CT/NRN NJ/MD/FAR
   NRN VA/WV PANHANDLE
   
   CONCERNING...WINTER MIXED PRECIPITATION
   
   VALID 160118Z - 160545Z
   
   PRIMARILY FREEZING RAIN...WITH POTENTIAL FOR ICE
   ACCUMULATIONS...WILL CONTINUE TO TRANSITION NEWD ACROSS CNTRL/ERN
   PA...NRN NJ...INTO SRN/CNTRL NY AND WRN CT THIS EVENING. ACROSS WRN
   PA/WRN NY...A CHANGE OVER TO ALL SNOW IS EXPECTED THIS
   EVENING...WITH MDT/LOCALLY HEAVY SNOW DEVELOPING BY LATE
   EVENING/OVERNIGHT. FURTHER SOUTH...INITIAL FREEZING RAIN SHOULD
   CHANGE OVER TO RAIN ACROSS NRN VA/MUCH OF MD/SE PA/MOST OF NJ PRIOR
   TO 06Z.
   
   WITH BROAD NEGATIVE TILT TROUGH CENTERED OVER THE UPPER MISSISSIPPI
   VALLEY...VORTICITY MAX AND STRONG MID/UPPER JET CONTINUES TO RACE
   EWD TOWARD THE MID ATLANTIC/NORTHEAST STATES WITHIN BASE OF UPPER
   TROUGH. ACCORDINGLY...BROAD/DEEP FORCING FOR ASCENT IS CONTRIBUTING
   TO NEWD TRANSITION OF BROAD PRECIPITATION SHIELD INTO THE NORTHEAST
   STATES.
   
   AS SEEN IN THE 00Z WASHINGTON-DULLES RAOB...NWD EXTRAPOLATION OF
   ELEVATED MELTING LAYER WILL REMAIN SUPPORTIVE OF FREEZING RAIN AS
   PRIMARY PRECIP-TYPE ACROSS MUCH OF CNTRL/ERN PA AND NRN NJ INTO
   SRN/CNTRL NY AND WRN CT MUCH OF THE EVENING...WHERE WEDGE OF SHALLOW
   COLD AIR WILL BE MAINTAINED. SOME SLEET/SNOW WILL BE POSSIBLE AS
   WELL.
   
   FURTHER WEST...00Z PITTSBURG AND 00Z BUFFALO RAOBS FEATURE A 1-2C
   WARM LAYER NEAR 850 MB...STILL AT LEAST MARGINALLY SUPPORTIVE OF
   FREEZING RAIN/SOME SLEET. HOWEVER...WITH NOCTURNAL/DYNAMIC COOLING
   AND EVENTUAL COLD ADVECTION...21Z RUC GUIDANCE SUGGESTS A GRADUAL
   CHANGE OVER TO ALL SNOW SHOULD OCCUR ACROSS MUCH OF WRN PA/WRN NY BY
   LATE EVENING...WITH MDT/LOCALLY HEAVY SNOW PREVALENT INTO THE
   OVERNIGHT. SNOW RATES MAY REACH 1 IN/HR IN THESE AREAS BY 06Z.
   
   ..GUYER.. 12/16/2005
   
   
   ATTN...WFO...BOX...OKX...ALY...PHI...BGM...BUF...CTP...LWX...PBZ...RLX...CLE...
   
   43007437 41607284 41177380 40127503 39637663 39227774
   38567885 38737931 39677952 40097994 41568027 43177865
   43397632

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   MESOSCALE DISCUSSION 2576
   NWS STORM PREDICTION CENTER NORMAN OK
   1247 AM CST FRI DEC 16 2005
   
   AREAS AFFECTED...MUCH OF NEW ENGLAND/NRN APPALACHIANS
   
   CONCERNING...WINTER MIXED PRECIPITATION
   
   VALID 160647Z - 161215Z
   
   A MIX OF FREEZING RAIN/SLEET AND SNOW WILL DEVELOP ACROSS MUCH OF
   NEW ENGLAND OVERNIGHT. FREEZING RAIN WILL CHANGEOVER TO MODERATE TO
   HEAVY SNOW /HRLY RATES UP TO 1 INCH/ ACROSS PORTIONS OF CENTRAL/NRN
   PA INTO WRN/NRN NY...WITH FREEZING RAIN CHANGING OVER TO RAIN OVER
   FAR NRN NJ/NERN PA...THE LOWER HUDSON RIVER VALLEY AND MUCH OF CT
   THROUGH 12Z. HOURLY FREEING RAIN/SLEET RATES AROUND 0.10 INCH WILL
   BE COMMON ACROSS PORTIONS OF THE MIDDLE HUDSON RIVER VALLEY OF
   ECENTRAL NY AND WRN PORTIONS OF MA/FAR SRN VT/SRN NH...LEADING TO
   THE POTENTIAL FOR SIGNIFICANT SLEET AND ICING IN THESE AREAS THROUGH
   12Z.
   
   STRONG LOW LEVEL WAA WILL CONTINUE IN ADVANCE OF POTENT UPPER TROUGH
   MOVING THROUGH THE OHIO VALLEY. AT THE SURFACE...THE TREND OF A
   SLOWLY LIFTING SURFACE 32 DEG F LINE WILL CONTINUE OVERNIGHT AS A
   SURFACE LOW PRESSURE CENTERED OVER NEAR BWI AT 05Z LIFTS TOWARDS NYC
   BY 12Z. THEREFORE...NRN NJ...NERN PA...THE LOWER HUDSON RIVER VALLEY
   AND MUCH OF CT WILL SEE A CHANGEOVER FROM FREEZING PRECIP TO RAIN
   THROUGH 12Z. FURTHER NORTH...THE STRENGTH OF THE WAA AND GRADUAL
   SHRINKING OF THE ELEVATED WARM LAYER DEPTH DUE TO ASCENT WILL
   SUPPORT A MIX OF MODERATE TO OCCASIONALLY HEAVY FREEZING RAIN AND
   SLEET ACROSS MUCH OF ECENTRAL/NERN NY...VT/NH AND MA THROUGH 12Z.
   
   FURTHER WEST...LOW LEVEL CAA WAS COMMENCING PER VWP DATA AT PBZ. IN
   ADDITION...MID LEVEL FRONTOGENESIS WILL CONTINUE TO INTENSIFY IN THE
   700-600 MB LAYER SUPPORTING DENDRITIC SNOW GROWTH. THESE TWO WILL
   COMBINE TO AID IN A CHANGEOVER OF P-TYPE FROM FREEZING RAIN TO
   MOD-HVY SNOW OVER NCENTRAL PA NWD INTO WRN/NRN NY...ESPECIALLY
   DURING THE 08-12Z TIME FRAME.
   
   ..CROSBIE.. 12/16/2005
   
   
   ATTN...WFO...GYX...BOX...BTV...OKX...ALY...PHI...BGM...BUF...CTP...PBZ...
   
   44387148 43317068 42237116 41737201 41157332 41117459
   41077533 40937637 40587783 41147903 43077776 44837533
   44907298

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   MESOSCALE DISCUSSION 2577
   NWS STORM PREDICTION CENTER NORMAN OK
   0554 AM CST FRI DEC 16 2005
   
   AREAS AFFECTED...NERN NY...VT...NH...ME...NWRN MA
   
   CONCERNING...PRECIPITATION TRENDS...WINTER PRECIPITATION
   
   VALID 161154Z - 161700Z
   
   ...WINTER STORM PRODUCING AREAS OF ICE AND SNOW ACROSS THE
   NORTHEAST...
   
   FZRA WILL CREATE HAZARDOUS ICING FROM PARTS OF ERN NY... MA...SRN
   VT/NH...AND SWRN ME THIS MORNING. MDT TO HVY SN WILL FALL FROM
   CNTRL/NERN NY...AND ALONG THE CANADIAN BORDER FROM VT/NH TO INTERIOR
   MAINE. A BROAD TRANSITION ZONE OF SN...PL...AND FZRA WILL CONTINUE
   FROM CNTRL VT/NH TO MAINE THIS MORNING BEFORE CHANGING BACK TO SN BY
   AFTERNOON.
   
   AN INTENSE AND FAST-MOVING MID/UPPER LEVEL IMPULSE WAS ROTATING
   THROUGH THE ERN PERIPHERY OF A LARGE CLOSED LOW OVER WI THIS
   MORNING. DPVA ASSOCIATED WITH THE IMPULSE/JET HAS INDUCED SURFACE
   CYCLOGENESIS ALONG COASTAL BAROCLINIC ZONE VICINITY OF NJ. VERY
   TIGHT PRESSURE GRADIENT BETWEEN THE DEEPENING SECONDARY LOW AND A
   STRONG SURFACE HIGH OVER SRN QUEBEC WAS CONTRIBUTING TO PRONOUNCED
   INFLUX OF ATLANTIC MOISTURE NWWD AND INLAND ATOP SURFACE-BASED COLD
   DOME FROM ERN NY ACROSS NRN NEW ENGLAND.
   
   MID/UPPER LEVEL DRYING WAS DEVELOPING NEWD ACROSS VT/NH EARLY THIS
   MORNING BASED ON RECENT SATELLITE AND RADAR TRENDS. THIS WILL RESULT
   IN LOWER PCPN RATES IN THE SHORT TERM ACROSS THESE AREAS. WRF AND
   ENSEMBLE MEAN QPF WERE INDICATING ONE PCPN MAX ASSOCIATED WITH LIFT
   NEAR THE SURFACE LOW/BAROCLINIC ZONE...AND ANOTHER PCPN MAX FROM
   NERN NY TO SRN QUEBEC. AREAS IN THE SRN ZONE OF HEAVIER PCPN... FROM
   SERN NY ACROSS MA AND INTO SRN NH AND MAINE...MAY EXPERIENCE A
   PERIOD OF HVY ICING THIS MORNING AS WARMER AIR ALOFT CONTINUES TO
   SPREAD INLAND OVER THE SUB-FREEZING AIR AT THE SURFACE. SN WILL
   CHANGE TO A PERIOD OF FZRA IN THESE AREAS. THIS HAS ALREADY HAPPENED
   OVER SWRN MA...AND IS EXPECTED TO DEVELOP NEWD ACROSS SRN NH AND ME
   OVER THE NEXT FEW HOURS.
   
   FARTHER NORTH...SECONDARY PCPN MAXIMUM...FROM NERN NY ACROSS SRN
   QUEBEC...NRN VT/NH...AND INTERIOR ME...WILL LIKELY BE PRIMARILY IN
   THE FORM OF SN. INTENSE QG FORCING FOR ASCENT WILL CONTINUE TO PIVOT
   ENEWD FROM CNTRL/NERN NY THIS MORNING...AND ACROSS NRN NEW ENGLAND
   TO INTERIOR ME THROUGH THIS AFTERNOON. DYNAMIC COOLING IN THE LOW TO
   MID LEVELS WILL OFFSET WARM ADVECTION AND...COUPLED WITH INFLUX OF
   MOISTURE INTO THIS REGION...SUPPORT MDT TO HVY SN ON THE NRN EDGE OF
   THE PCPN TRANSITION ZONE. SN WILL TAPER OFF AND END FROM WEST TO
   EAST AS THE STRONGER UPPER FORCING MOVES ACROSS THESE AREAS THROUGH
   THE DAY.
   
   ..CARBIN.. 12/16/2005
   
   
   ATTN...WFO...CAR...GYX...BOX...BTV...ALY...BGM...BUF...
   
   46297016 45717074 45447138 45327257 45147396 44837539
   44267584 43177599 42847534 42817408 42127365 42057269
   42447120 42887082 43477058 44136923 45856858 46386920

[CaptinCrunch]

MESOSCALE DISCUSSION 2578
NWS STORM PREDICTION CENTER NORMAN OK
1245 PM CST FRI DEC 16 2005

AREAS AFFECTED...NRN VT/NH/MUCH OF ME

CONCERNING...HEAVY SNOW

VALID 161845Z - 162245Z



...SNOW WILL BE INCREASING IN INTENSITY ACROSS MUCH OF ME THIS
AFTN...WITH RATES OF 1 TO 2 INCHES PER HOUR. MODERATE TO HEAVY SNOW
WILL BE DIMINISHING ACROSS VT/NH WITHIN 1-3 HOURS...

LATEST SFC ANALYSIS SHOWS RAPIDLY FALLING SFC PRESSURE /2-3MB PER
HOUR OFFSHORE/ WITH LOW NOW NEAR BEDFORD. SYSTEM IS QUICKLY LIFTING
NORTHEAST WITH DRIER AIR APPROACHING FROM THE SW PER WV LOOPS.
COMPOSITE RADAR IMAGERY DEPICTS ENHANCED REFLECTIVITY RETURNS ACROSS
SRN ME NEAR PORTLAND. RECENT SFC OBSERVATIONS AT KDAW /DAWSON/
INDICATED HEAVY RAIN...WITH HEAVY SNOW NOW AT KIZG /FRYEBERG/...AS
THIS MORE INTENSE PRECIPITATION MOVES BY.

THERMAL PROFILES SUPPORT ALL SNOW...EXCEPT NEAR THE COASTAL AREAS
WHERE RAIN WILL OCCUR. SNOW RATES WILL BE ENHANCED BOTH BY STRONG
FRONTOGENESIS THROUGH A DEEP LAYER AND A SATURATED DENDRITIC
ZONE...WHICH FORECAST SOUNDINGS SUGGEST WILL BE MAINTAINED TIL AT
LEAST 21Z AROUND KBGR AND THROUGH 00Z NEAR KCAR.

HEAVY SNOW NOW ONGOING ACROSS NRN PORTIONS OF VT/NH WILL END WITHIN
A COUPLE HOURS. BUT IT APPEARS MODERATE TO HEAVY SNOW WILL CONTINUE
ACROSS MUCH OF ME THROUGH THE AFTN.

..TAYLOR.. 12/16/2005

[TexasStooge]

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   MESOSCALE DISCUSSION 2579
   NWS STORM PREDICTION CENTER NORMAN OK
   0214 AM CST SUN DEC 18 2005
   
   AREAS AFFECTED...CA SIERRA NEVADA MOUNTAINS
   
   CONCERNING...HEAVY SNOW
   
   VALID 180814Z - 181415Z
   
   HEAVY WET SNOW IS EXPECTED TO OVERSPREAD THE SIERRA RANGE IN THE
   NEXT SEVERAL HOURS AS MOIST PACIFIC STORM SYSTEM MOVES INLAND.
   SNOWFALL RATES AOA 6000 FEET COULD EXCEED 2 INCHES PER HOUR THIS
   MORNING.
   
   OVER THE NEXT SEVERAL HOURS...PRECIPITATION RATES WILL CONTINUE TO
   INCREASE AND SPREAD INLAND FROM THE COAST AND ACROSS THE CNTRL
   VALLEY OF CA AS POTENT PACIFIC PERTURBATION MOVES EAST ACROSS THE
   NCNTRL CA COAST. OBSERVED RAINFALL RATES NEAR THE COAST WERE ALREADY
   IN THE RANGE OF 0.10 TO 0.25 INCHES PER HOUR WITHIN WARM AIR
   ADVECTION REGIME AHEAD OF THE STRONGER DYNAMIC FORCING. /REF
   NFDSPENES WMO HEADER TXUS20/.
   
   INTENSIFYING UPSLOPE FLOW AND DYNAMIC FORCING WITH THE MID/UPPER
   LEVEL IMPULSE/WIND MAX...ALONG WITH ENHANCED MOISTURE TRANSPORT
   ACCOMPANYING +1 INCH PW PLUME...WILL LEAD TO EXCESSIVE SNOWFALL
   RATES DEVELOPING ACROSS THE HIGHER ELEVATIONS THROUGH 12Z. WHILE
   SNOW LEVELS MAY INITIALLY CLIMB ABOVE 6000 FEET...FREEZING LEVELS
   WILL BEGIN TO FALL LATER THIS MORNING AS ADIABATIC COOLING WITHIN
   THE UPPER TROUGH AXIS SPREADS ACROSS THE AREA. WITH POTENTIAL FOR
   EMBEDDED CONVECTION...AND DECENT AGREEMENT IN LATEST SHORT-TERM QPF
   GUIDANCE FROM NAM AND RUC MODELS...SNOWFALL RATES OF 2-4 INCHES PER
   HOUR APPEAR LIKELY NEAR AND SOUTH OF THE TAHOE AREA BEFORE 12Z.
   WINDS ALSO INCREASING TO NEAR 50KT LATER THIS MORNING WILL PRODUCE
   DRIFTING SNOW AND WHITE-OUT CONDITIONS.
   
   ..CARBIN.. 12/18/2005
   
   
   ATTN...WFO...VEF...REV...HNX...STO...
   
   37021850 36771865 37371945 37972000 38232022 38682029
   39242058 39532070 39762078 40232140 40502156 40502133
   40442108 40292076 40112059 39902037 39672017 38932008
   37431870

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   MESOSCALE DISCUSSION 2580
   NWS STORM PREDICTION CENTER NORMAN OK
   1255 PM CST SUN DEC 18 2005
   
   AREAS AFFECTED...CNTRL AND ERN ORE/SIERRA/NRN NV
   
   CONCERNING...HEAVY SNOW
   
   VALID 181855Z - 190100Z
   
   ...MODERATE TO HEAVY SNOW WILL CONTINUE ACROSS THE NRN GREAT BASIN
   THROUGH AFTN...WITH SNOW SPREADING INTO THE ERN SLOPES OF THE
   CASCADES WITHIN A FEW HOURS. SNOW RATES ABOVE 4000 FEET MAY BE IN
   THE 2-3 INCH PER HOUR RANGE...
   
   LATEST IR SATELLITE IMAGERY SHOWS INCREASING MOISTURE/CLOUDS MOVING
   ACROSS SRN ID/ORE WITH SOME COOLING CLOUD TOPS NOTED. ENHANCED BAND
   OF CLOUDS SEEMS TO BE ASSOCIATED WITH DEFORMATION BAND NEAR 700MB.
   HEAVIEST SNOW CURRENTLY OVER NRN PORTIONS OF NV FROM LOL/WMC/EKO.
   MEANWHILE...SNOW HAS CHANGED OVER TO RAIN IN THE TAHOE/RENO
   AREA...SUGGESTING FROM THE SFC OBSERVATIONS THAT THE FREEZING LEVEL
   HAS RISEN ABOVE 6000 FEET.
   
   BAND OF SNOW IS EXPECTED TO INCREASE FROM DESCHUTES CO ORE INTO SW
   ID AND NW UT...ASSOCIATED WITH FRONTOGENETIC FORCING WITHIN THE
   750-650 MB LAYER AND UPWARD MOTION DUE TO VORTICITY ADVECTION. THIS
   IS SUPPORTED BY THE ETA/RUC/GFS. SNOW RATES MAY RANGE FROM 1 TO 2
   INCHES PER HOUR. SOME FZRA HAS BEEN OBSERVED NORTH OF MEDFORD
   EARLIER...BUT MOST LOCATIONS HAVE TEMPS ABOVE FREEZING NOW.
   EXCEPTION MAY BE IN VALLEY LOCATIONS WHERE STRONG INVERSION IS
   HOLDING DOWN TEMPS. HEAVY SNOW WILL ALSO CONTINUE IN THE HIGHER
   ELEVATIONS OF THE SIERRA
   
   ..TAYLOR.. 12/18/2005
   
   
   ATTN...WFO...BOI...LKN...PDT...REV...MFR...PQR...
   
   39391884 40252000 41862008 42232251 43122257 45402189
   45511851 44741731 42231521 40151489

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   MESOSCALE DISCUSSION 2581
   NWS STORM PREDICTION CENTER NORMAN OK
   0657 PM CST SUN DEC 18 2005
   
   AREAS AFFECTED...SW WA/MUCH OF ORE/SW ID/NRN UT
   
   CONCERNING...FREEZING RAIN/SNOW
   
   VALID 190057Z - 190600Z
   
   ...FZRA WILL AFFECT THE INTERIOR VALLEYS OF NW ORE/SW WA TONIGHT
   WITH MODERATE/HEAVY SNOW FROM THE COLUMBIA GORGE SEWD TO SW ID/NRN
   UT...
   
   FIRST IN A SERIES OF UPPER IMPULSES IS NOW ROTATING ONSHORE WITH AN
   UPPER CIRCULATION CENTER APPARENT IN EVENING WATER VAPOR IMAGERY
   MOVING INTO SW ORE. STAGNANT COLD AIRMASS HAS BEEN TRAPPED WITHIN
   THE VALLEYS FOR THE PAST FEW DAYS...AND WITH STRONG LARGE SCALE
   ASCENT AND MOISTURE IN PLACE...FZRA WILL RESULT ACROSS SOME
   LOCATIONS TONIGHT. THERE HAS BEEN FZRA DURING THE LAST COUPLE OF
   HOURS AT SALEM AND IN EUGENE EARLIER. 00Z SOUNDING FROM SALEM SHOWED
   NEAR FREEZING TEMPS FROM ABOUT 925MB-750MB...BUT RECENT MODERATE
   SNOW REPORTS IN/NEAR PORTLAND INDICATE THE COLUMN IS COLD ENOUGH FOR
   SNOW AT LEAST INITIALLY. VEERING PROFILE FROM BOTH ORE UPPER AIR
   SOUNDINGS IMPLIES CONTINUED WARMING...WITH A MIX OF PCPN TYPES
   POSSIBLE.
   
   FORECAST SOUNDINGS FROM THE NAM/RUC SUGGEST FZRA COULD SPREAD FROM
   PORTLAND NWD INTO THE INTERIOR VALLEYS OF SW WA BY 03Z AND NEAR
   OLYMPIA TOWARD 06Z. THE PTYPE ALGORITHM AND THE NCEP SREF SHOW AN
   EVEN STRONGER SIGNAL OF FZRA...ESPECIALLY AFTER 06Z. ACROSS NERN
   PORTIONS OF ORE INTO ID/UT...SNOW IS EXPECTED WITH HRLY RATES OF 1
   TO 2 INCHES PER HOUR POSSIBLE...AND BOUTS OF HEAVY SNOW WILL ALSO
   CONTINUE OVERNIGHT ACROSS THE WASATCH.
   
   ..TAYLOR.. 12/19/2005
   
   
   ATTN...WFO...SLC...PIH...BOI...LKN...OTX...PDT...SEW...PQR...
   
   41311512 44102090 44762407 46692299 47432121 45381690
   41701120 40691196

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   MESOSCALE DISCUSSION 2582
   NWS STORM PREDICTION CENTER NORMAN OK
   0957 AM CST MON DEC 19 2005
   
   AREAS AFFECTED...ERN/NRN ORE...SERN WA...AND WRN ID
   
   CONCERNING...PRECIPITATION TRENDS...WINTER PRECIPITATION
   
   VALID 191557Z - 192000Z
   
   FREEZING RAIN WILL DIMINISH IN INTENSITY OVER THE WRN COLUMBIA RIVER
   GORGE THROUGH 18Z...WHILE A MIX OF SLEET AND FREEZING RAIN WILL
   DEVELOP FURTHER EAST OVER THE COLUMBIA RIVER BASIN OF NERN ORE/SERN
   WA THROUGH 20Z. HRLY ACCUMULATIONS UP TO 0.10 FOR AN HOUR OR TWO
   WILL BE POSSIBLE. FURTHER SOUTH...LIGHT SNOW WILL CONTINUE TO
   DEVELOP OVER THE TREASURE VALLEY OF FAR SERN ORE/SWRN ID THROUGH
   18Z...BEFORE A MIX AND THEN CHANGE OVER TO SLEET/FREEZING RAIN
   OCCURS IN THIS AREA BETWEEN 18-20Z. ACCUMULATIONS RATES UP TO 0.10
   INCH/HR WILL BE POSSIBLE IN THIS AREA AS WELL.
   
   STRONG MID LEVEL ISENTROPIC LIFT WAS CONTRIBUTING TO AN ORGANIZED
   NW-SE ORIENTED BAND OF PRECIPITATION MOVING EWD ACROSS SRN WA AND
   ERN ORE. AS THE UPPER WAVE CONTRIBUTING TO THIS LIFTS INTO BRITISH
   COLUMBIA...EXPECT A STEADY EWD PROGRESS OF THIS PRECIPITATION ACROSS
   MUCH OF NERN ORE/SERN WA THROUGH THE EARLY AFTERNOON HOURS. RECENT
   RUC/NAM FORECAST SOUNDINGS INDICATE THAT LIGHT SNOW WILL CHANGE OVER
   TO FREEZING RAIN OVER MUCH OF THE COLUMBIA RIVER BASIN OF NERN
   ORE/SERN WA THROUGH 20Z. FURTHER EAST...ISENTROPIC ASCENT WAS JUST
   NOW MOVING INTO THE UPPER TREASURE VALLEY OF SERN ORE/SWRN ID. IN
   THIS AREA...STRONG WAA...EVIDENT BY 60 KT SWLY JET AT 700 MB PER
   MEDFORD VWP...SUGGESTS THAT LIGHT SNOW NOW DEVELOPING INTO THIS AREA
   WILL CHANGE OVER TO FREEZING RAIN/SLEET BETWEEN 18-20Z.
   
   ..CROSBIE.. 12/19/2005
   
   
   ATTN...WFO...MSO...BOI...OTX...PDT...SEW...PQR...
   
   46861735 47211930 47202100 46882142 46252177 45802181
   45312147 45042090 44931996 44511932 43631865 42781781
   42461733 42461578 43101540 44491601 46021678

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   MESOSCALE DISCUSSION 2583
   NWS STORM PREDICTION CENTER NORMAN OK
   0156 PM CST MON DEC 19 2005
   
   AREAS AFFECTED...NRN/ERN ORE...SWRN ID AND SRN WA-
   
   CONCERNING...PRECIPITATION TRENDS...WINTER PRECIPITATION
   
   VALID 191956Z - 200100Z
   
   MODERATE SNOW OVER THE TREASURE VALLEY MAY CHANGEOVER TO LIGHT
   FREEZING RAIN THROUGH 21Z...BEFORE WEAKENING TOWARDS 00Z. FURTHER
   NORTH MIXED PRECIP OVER NERN ORE/SERN WA...INCLUDING MUCH OF THE
   COLUMBIA RIVER BASIN...WILL CONTINUE TO DIMINISH THROUGH THE
   AFTERNOON. HOWEVER...A NEW AREA OF FREEZING RAIN WILL REDEVELOP
   AFTER 22Z IN THE DESCHUTES RIVER VALLEY OF NRN ORE AND OVER THE WRN
   COLUMBIA RIVER BASIN/GORGE AFTER 00Z.
   
   LATEST RADAR IMAGERY INDICATES A LARGE AREA OF PRECIPITATION OVER
   ERN ORE...ASSOCIATED WITH MODERATE-STRONG MID LEVEL WAA/ISENTROPIC
   LIFT. AS OF YET...THE WAA HAS BEEN INSUFFICIENT TO ALLOW FOR A
   CHANGEOVER TO FREEZING RAIN IN THE TREASURE VALLEY WITH MODERATE
   SNOWFALL THE PRIMARY P-TYPE. GIVEN RECENT TRENDS IN OBSERVATIONS AT
   BURNS /ELEV 4000 FT/ INDICATING ABOVE FREEZING TEMPERATURES
   DEVELOPING ...THERE IS STILL SOME POTENTIAL THAT SNOW WILL
   CHANGEOVER TO FREEZING RAIN BEFORE PRECIPITATION DIMINISHES BY LATE
   THIS AFTERNOON.
   
   FURTHER NW...RADAR IMAGERY AND SURFACE OBSERVATIONS INDICATE THAT
   WEAKENING MIXED PRECIP RATES WILL CONTINUE OVER MUCH OF THE COLUMBIA
   RIVER BASIN REGION THROUGH THE REMAINDER OF THE AFTERNOON AS MID
   LEVEL ISENTROPIC LIFT SHIFTS EWD AWAY FROM THE AREA. UPSTREAM OF
   THIS AREA...ANOTHER SURGE OF STRONG MID LEVEL WAA WAS BEGINNING
   AHEAD OF DEEP SYSTEM WELL OFF THE ORE COAST. THE ASSOCIATED
   PRECIPITATION WAS ALREADY ADVANCING NWD ALONG THE CENTRAL ORE COAST
   AND WILLAMETTE VALLEY. AS THIS PRECIPITATION ADVANCES
   NEWD...SUBFREEZING AIR WILL REMAIN IN PLACE OVER THE WRN COLUMBIA
   RIVER BASIN...COLUMBIA GORGE AND DESCHUTES VALLEY. THUS ANOTHER
   ROUND OF LIGHT TO MODERATE FREEZING RAIN WILL DEVELOP BETWEEN
   22-01Z.
   
   ..CROSBIE.. 12/19/2005
   
   
   ATTN...WFO...MSO...BOI...OTX...PDT...SEW...PQR...
   
   46911830 46751993 46592117 46392195 46222219 45492219
   45042202 44252169 44302124 44962022 45081900 44701828
   42881643 42671594 43311556 44691617 46701708

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   MESOSCALE DISCUSSION 2584
   NWS STORM PREDICTION CENTER NORMAN OK
   0730 PM CST MON DEC 19 2005
   
   AREAS AFFECTED...NERN ORE/ERN WA
   
   CONCERNING...PRECIPITATION TRENDS...WINTER PRECIPITATION
   
   VALID 200130Z - 200630Z
   
   FREEZING RAIN WILL CONTINUE TO DEVELOP OVER THE WRN COLUMBIA RIVER
   BASIN/GORGE OF NRN ORE THROUGH 03Z. FREEZING RAIN WILL EVENTUALLY
   DEVELOP INTO THE ERN SLOPES OF THE CASCADES AND COLUMBIA RIVER BASIN
   OF ERN WA BETWEEN 03-06Z. A COUPLE HOUR PERIOD OF HRLY PRECIP RATES
   UP TO 0.05 INCH WILL BE POSSIBLE...ESPECIALLY WITHIN 1-2 HOURS OF
   ONSET OF PRECIPITATION.
   
   AN AREA OF MOD-OCCASIONALLY HEAVY PRECIPITATION OVER NWRN ORE HAS
   DEVELOPED IN AN AREA OF MODERATE WAA AHEAD OF DEEP UPPER CYCLONE
   WELL OFF THE ORE COAST. THIS PRECIPITATION WILL CONTINUE TO SPREAD
   NEWD INTO THE COLUMBIA RIVER BASIN THROUGH THE LATE EVENING HOURS ON
   THE HEAL OF A 50-60 KT LOW LEVEL SSWLY JET. RECENT SURFACE
   OBSERVATIONS INDICATE HRLY RAINFALL RATES UP TO 0.2O INCH OVER THE
   NRN WILLAMETTE VALLEY. ALTHOUGH LOW LEVEL FLOW WILL REMAIN SSWLY
   WHICH SHOULD AID IN SOME SUBSIDENCE ON THE LEE-SIDE OF THE
   CASCADES...AND THUS LOWER HRLY PRECIP AMOUNTS...SUFFICIENTLY DEEP
   VERTICAL MOTION SHOULD ALLOW FOR LIGHT TO OCCASIONALLY MODERATE
   FREEZING RAIN TO DEVELOP INTO THE SERN SLOPES OF THE WA CASCADES AND
   COLUMBIA RIVER BASIN OF WA BETWEEN 03-06Z.
   
   FURTHER SOUTH...AS THE BULK OF THE LOW LEVEL LIFT/PRECIP CONTINUES
   TO MOVE NWD...EXPECT A DIMINISHING OF THE FREEZING RAIN RATES OVER
   THE DESCHUTES VALLEY THROUGH 06Z.
   
   ..CROSBIE.. 12/20/2005
   
   
   ATTN...WFO...OTX...PDT...PQR...
   
   47211981 47692030 47472102 47142094 46002160 45532231
   45032185 44682168 44632070 44672056 45421981 46461970

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MESOSCALE DISCUSSION 2599
NWS STORM PREDICTION CENTER NORMAN OK
1229 PM CST THU DEC 29 2005

AREAS AFFECTED...NORTHERN SOUTH DAKOTA...SOUTHERN NORTH DAKOTA

CONCERNING...WINTER MIXED PRECIPITATION

VALID 291829Z - 300030Z



A SWATH OF MODERATE TO HEAVY SNOW LOCALLY PRECEEDED BY MIXED
PRECIPITATION IS EXPECTED ACROSS NORTHERN SOUTH DAKOTA AND SOUTHERN
NORTH DAKOTA THIS AFTERNOON WITH LOCALIZED SNOWFALL RATES
APPROACHING ONE INCH PER HOUR.

A UPPER LEVEL STRONG SHORT WAVE TROUGH EVIDENT IN WATER VAPOR
IMAGERY AND RUC ANALYSES OVER CENTRAL COLORADO WILL PROGRESS
EASTWARD AND COMBINE WITH LOW LEVEL CYCLOGENESIS TO PRODUCE DEEP
LAYER ASCENT OVER THE THREAT AREA THIS AFTERNOON. STRONG 800-700 MB
LAYER FRONTOGENESIS IN RUC FCST ALSO HELPS FOCUS ASCENT NEAR ND...SD
BORDER AREA THIS AFTERNOON.

AT 14Z... 105 KNOT WINDS AT 9KM WERE OBSERVED AT THE PLATTEVILLE CO
WIND PROFILER AS THE JET STREAK AXIS SLID EASTWARD ACROSS COLORADO.
SITUATION IS COMPLICATED BY A WEAKER LEAD SHORTWAVE CURRENTLY
EVIDENT IN WV AND RUC ANALYSES OVER SW SD CURRENTLY CONTRIBUTING TO
MODERATE SNOWFALL OVER SOUTHERN ND. BOTH RUC AND SREF APPEAR TO HAVE
A POOR HANDLE ON THIS FEATURE.

MODIFIED PACIFIC AIRMASS IS EVIDENT OVER PORTIONS OF NORTHWEST
NEBRASKA AND EASTERN WY AND MT WITH GPS PW OF NEARLY THREE QUARTER
INCH CURRENTLY OBSERVED NEAR CDR EARLIER TODAY. RUC AND NCEP SREF
AGREE THAT LOCALIZED INCH PER HOUR SNOWFALL RATES ARE POSSIBLE...IN
PARTICULAR LATE IN THE PERIOD. TYPICAL POLAR AIRMASS IS ABSENT
ACROSS THE EASTERN US SO COOLING OF THE LAYER THROUGH DEEP ASCENT
AND EVAPORATION WILL BE NECESSARY IN PORTIONS OF THE THREAT AREA
BEFORE THE ONSET OF FROZEN PRECIPITATION. THE PRESENCE OF THE POORLY
HANDLED LEAD SHORTWAVE COMBINED WITH OBSERVED MODERATE RAIN WITH
ABOVE FREEZING TEMPERATURE AT MBG SD AT 18Z SHIFTED FOCUS OF WINTER
PRECIPITATION SLIGHTLY NORTHWARD BUT CONFIRMS POTENTIAL FOR INCH AN
HOUR RATES IN SNOW AREAS. 12Z ABR SOUNDING HAD ONLY A SHALLOW
ABSOLUTELY STABLE LAYER WITH WET BULB TEMPERATURES ABOVE ZERO
DESPITE 150MB DEEP LAYER WITH A DRY BULB TEMPERATURE ABOVE FREEZING.
MODEL SOUNDINGS SUGGEST THAT PRECIPITATION WILL TRANSITION FROM
FREEZING RAIN TO MIXED PRECIPITATION AND MAINLY SNOW OVER NORTHEAST
SD BETWEEN 21 AND 03Z. HEAVIEST PRECIPITATION RATES WILL SPREAD FROM
WEST TO EAST ACROSS THE THEAT AREA THIS AFTERNOON AND EVENING.

..SCHNEIDER.. 12/29/2005

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   MESOSCALE DISCUSSION 2600
   NWS STORM PREDICTION CENTER NORMAN OK
   0608 PM CST THU DEC 29 2005
   
   AREAS AFFECTED...SE SD...SRN MN...NRN IA
   
   CONCERNING...WINTER MIXED PRECIPITATION
   
   VALID 300008Z - 300415Z
   
   A LARGE AREA OF FREEZING RAIN MIXED WITH SNOW WILL SPREAD EWD AND
   GRADUALLY CHANGE OVER TO ALL SNOW ACROSS SE SD...SRN MN AND NRN IA.
   
   WATER VAPOR IMAGERY CURRENTLY SHOWS AN UPPER-LEVEL TROUGH OVER WRN
   SD AND WRN NEB WITH A DRY SLOT AND DEFORMATION ZONE EXPANDING EWD
   ACROSS ERN SD AND NE NEB. STRONG LIFT ASSOCIATED WITH THE LEFT FRONT
   QUADRANT OF THE MID-LEVEL JET AND STRONG DIVERGENCE ALOFT SHOWN ON
   THE SHORT-TERM MODEL FORECASTS IS RESULTING IN WIDESPREAD
   PRECIPITATION EXTENDING EWD FROM THE DEFORMATION ZONE. FORECAST
   SOUNDINGS ACROSS SRN MN AND NRN IA SHOW AN ABOVE FREEZING LAYER FROM
   900 TO 800 MB. AS THE SYSTEM DRIFTS EWD TONIGHT THIS WARM LAYER WILL
   ERODE FROM WEST TO EAST RESULTING IN A CHANGEOVER TO ALL SNOW.
   ISOLATED HEAVY SNOWFALL RATES OF GREATER THAN 1 INCH PER HOUR WILL
   BE POSSIBLE ESPECIALLY AS THE WRAP AROUND ASSOCIATED WITH THE
   MID-LEVEL LOW DRIFTS EWD INTO SE SD AROUND MIDNIGHT. THIS AREA OF
   HEAVIER SNOWFALL SHOULD DRIFT EWD INTO SRN MN AND NRN IA DURING THE
   OVERNIGHT HOURS.
   
   ..BROYLES.. 12/30/2005
   
   
   ATTN...WFO...ARX...MPX...DMX...FSD...OAX...ABR...
   
   42689337 42759776 43299893 43989893 44699749 44759354
   44239166 43159141

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   MESOSCALE DISCUSSION 2601
   NWS STORM PREDICTION CENTER NORMAN OK
   0617 PM CST THU DEC 29 2005
   
   AREAS AFFECTED...SE NORTH DAKOTA...NE SOUTH DAKOTA...WEST CNTRL
   MINNESOTA
   
   CONCERNING...HEAVY SNOW
   
   VALID 300017Z - 300615Z
   
   SNOWFALL RATES WILL APPROACH 1 INCH PER HOUR OVER SOUTHEAST NORTH
   DAKOTA...NORTHEAST SOUTH DAKOTA...AND WEST CENTRAL MINNESOTA.
   
   A LOW PRESSURE SYSTEM OVER CENTRAL SOUTH DAKOTA WILL CONTINUE TO
   MOVE EASTWARD INTO NORTHERN IOWA.  THE UPWARD VERTICAL MOTION
   ASSOCIATED WITH A STRONG UPPER LEVEL WAVE MOVING THROUGH THE
   AREA...COUPLED WITH THE LEFT EXIT REGION OF A JET AND DECENT UPPER
   DIVERGENCE...WILL AID IN THE DEVELOPMENT OF SNOW BANDS AND HEAVY
   SNOW ACROSS THE REGION FOR MOST OF THE EVENING.  MODERATE TO HEAVY
   SNOWFALL WILL BE THE MAJOR PRECIPITATION TYPE ACROSS THE NORTHERN
   PART OF THE REGION.  ACCORDING TO THE GFS AND NAM...WHICH ARE IN
   FAIRLY GOOD AGREEMENT...SOME LOCALLY TRANSIENT SLEET AND FREEZING
   RAIN...ALONG WITH SNOW...WILL OCCUR IN THE SOUTHERN PART OF THE
   REGION.  THE STORM SYSTEM WILL CONTINUE TO MOVE EASTWARD THROUGH THE
   PERIOD AND PRECIPITATION IS EXPECTED TO DECREASE TOWARDS FRIDAY
   MORNING.
   
   ..LEVIT.. 12/30/2005
   
   
   ATTN...WFO...MPX...FGF...ABR...BIS...
   
   46900166 47170041 47209857 47209689 47049542 46209494
   45659583 45369703 45269839 45300057 45680171

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   MESOSCALE DISCUSSION 2602
   NWS STORM PREDICTION CENTER NORMAN OK
   1140 PM CST THU DEC 29 2005
   
   AREAS AFFECTED...NERN OREGON INTO EXTREME SWRN ID
   
   CONCERNING...HEAVY SNOW
   
   VALID 300540Z - 301145Z
   
   MDT TO HVY SNOW IS EXPECTED TO DEVELOP BY AROUND 09Z MAINLY OVER
   NERN OREGON...WITH 1.50-2.00 IN/HR SNOW RATES POSSIBLE IN UPSLOPE
   REGION AND 1.00 IN/HR POSSIBLE LOWER ELEVATIONS. SNOW WILL THEN
   SHIFT EWD TOWARD 12Z INTO SWRN ID WHERE A MIXTURE OF RAIN AND HEAVY
   WET SNOW APPEAR LIKELY INTO THE LOWER TREASURE VALLEY.
   
   PRECIPITATION SHIELD IS EXPECTED TO GRADUALLY FILL IN ACROSS ERN
   OREGON AS SWLY FLOW BRINGS IN HIGHER PRECIPITABLE WATER CONTENT.
   UPWARD VERTICAL MOTIONS FIELDS WILL INCREASE AS ZONE OF
   FRONTOGENETICAL FORCING MATERIALIZES NEAR LEADING EDGE OF WARM/MOIST
   ADVECTION ALOFT. LIFTING ZONE IS EXPECTED TO LIE ALONG A NW-SE AXIS
   FROM THE MTNS OF NERN OREGON INTO FAR SWRN ID BY 12Z. RUC AND NAM
   FORECAST SOUNDINGS INDICATE STRONG VERTICAL MOTION CENTERED AROUND
   550-500 MB LAYER WHICH IS COINCIDENT WITH FAVORABLE TEMPERATURE
   LAYER FOR DENDRITIC GROWTH. THIS...COMBINED WITH SATURATED AND
   SUB-ZERO PROFILES IN THE SFC-700 MB LAYER AND SURFACE WET BULB ZERO
   TEMPERATURES NEAR FREEZING SHOULD RESULT IN LOCALLY HEAVY SNOWFALL
   RATES...ESPECIALLY IN THE HIGHER TERRAIN WHERE SLY FLOW WILL ENHANCE
   UPSLOPE. PRECIPITATION MAY BEGIN AS RAIN IN THE LOWER TREASURE
   VALLEY...BUT COULD CHANGE TO HVY WET SNOW DURING HEAVIEST
   PRECIPITATION RATE PERIOD...WHICH WILL GENERALLY OCCUR AFTER 12Z.
   
   ..JEWELL.. 12/30/2005
   
   
   ATTN...WFO...BOI...PDT...
   
   44081904 44981929 45581858 45641758 45581746 45201696
   44941673 44301665 43871676 43321698 43291819 43641860

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   MESOSCALE DISCUSSION 2603
   NWS STORM PREDICTION CENTER NORMAN OK
   1145 PM CST THU DEC 29 2005
   
   AREAS AFFECTED...ERN SD...SRN AND CNTRL MN...NRN IA
   
   CONCERNING...HEAVY SNOW
   
   VALID 300545Z - 300945Z
   
   AREAS OF HEAVY SNOW WILL CONTINUE ACROSS ERN SD...SRN AND CNTRL MN
   AND NRN IA DURING THE OVERNIGHT PERIOD. SNOWFALL RATES GREATER THAN
   1 INCH PER HOUR WILL BE POSSIBLE IN THE HEAVIER SNOW BANDS.
   
   WATER VAPOR IMAGERY CURRENTLY SHOWS AN UPPER-LOW LOCATED ACROSS THE
   CNTRL DAKOTAS. A SHORTWAVE TROUGH EXTENDED SWD ACROSS CNTRL NEB WITH
   A DEFORMATION ZONE SETTING UP ACROSS WRN IA AND SERN SD. STRONG LIFT
   ASSOCIATED WITH THE TROUGH AND THE LEFT EXIT REGION OF THE MID-LEVEL
   JET WILL CONTINUE TO SUPPORT WIDESPREAD SNOWFALL ACROSS THE REGION
   OVERNIGHT. FORECAST SOUNDINGS ACROSS SRN MN...ERN SD AND NW IA SHOW
   THAT THE WARM LAYER BETWEEN 900 AND 800 MB THAT WAS PRESENT EARLIER
   HAS COOLED BELOW FREEZING IN MOST AREAS. AS A RESULT...SNOW WILL BE
   THE FAVORED MODE OF PRECIPITATION ALTHOUGH A FEW SPOTS OF FREEZING
   RAIN AND/OR SLEET WILL STILL BE POSSIBLE. THE STRONG LARGE-SCALE
   ASCENT AND ISENTROPIC LIFT NORTHEAST OF THE DEFORMATION ZONE WILL
   CONTINUE TO RESULT IN BANDS OF MODERATE TO HEAVY SNOW. THE HEAVIEST
   SNOWBANDS SHOULD BE ACROSS SE SD...FAR NRN IA AND SRN MN WHERE THE
   STRONGEST DIVERGENCE ALOFT SHOULD BE LOCATED.
   
   ..BROYLES.. 12/30/2005
   
   
   ATTN...WFO...ARX...MPX...DMX...FSD...OAX...ABR...
   
   42759727 43359805 44569811 45459724 45639572 45579387
   44959255 43969202 42919279 42569537 42609557