Post-Christmas severe weather outbreak?

[wx247]

Here we go again... Will be around to keep you updated from SW MO tomorrow. The NWS will hold a conference call on the NOAA Weather Radio tmrw. at 10 a.m.

[CrazyC83]

Here we go again... Will be around to keep you updated from SW MO tomorrow. The NWS will hold a conference call on the NOAA Weather Radio tmrw. at 10 a.m.

I have a feeling you'll be in the center of it all...

[Ed Mahmoud]

Here we go again... Will be around to keep you updated from SW MO tomorrow. The NWS will hold a conference call on the NOAA Weather Radio tmrw. at 10 a.m.

Looking at soundings around SW Missouri, morning hours, low CAPE, below 500 J/Kg, and no instability the first 5000 feet, (good above as seen in TT over 50, even with the beginning of appreciable instability a bit above the 850 mb level) but impressive speed and directional shear, and 50 knot winds just above the deck to mix down from even an otherwise "garden variety" storm.



Later and farther East, model forecast surface CAPE basically nil, everything looks forced on the front, but 850 mb winds near 70 knots suggests hurricane force gusts possible with the squall line.

[CrazyC83]

SPC AC 260553

DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1153 PM CST THU DEC 25 2008

VALID 261200Z - 271200Z

...THERE IS A SLGT RISK OF SVR TSTMS ACROSS PARTS OF ERN OK...NE
TX...WRN AR...SE KS AND MO...

...SRN PLAINS/OZARKS...
A WELL-DEVELOPED UPPER-LEVEL TROUGH OVER THE INTERMOUNTAIN WEST
TODAY WILL MOVE INTO THE ROCKIES TONIGHT. AHEAD OF THE SYSTEM...A 50
TO 60 KT LOW-LEVEL JET WILL BE IN PLACE FROM EAST TX EXTENDING NEWD
INTO THE MID-MS VALLEY. THIS FEATURE WILL RESULT IN RAPID MOISTURE
RETURN ACROSS THE SRN PLAINS AND OZARK REGION. SFC DEWPOINTS OF AT
LEAST 60 F APPEAR LIKELY TO OVERSPREAD MUCH OF ERN OK...AR AND SRN
MO BY THIS EVENING. AS LARGE-SCALE ASCENT INCREASES AHEAD OF THE
APPROACHING UPPER-LEVEL TROUGH...NUMEROUS THUNDERSTORMS SHOULD
DEVELOP ALONG THE WRN EDGE OF THE LOW-LEVEL JET FROM CNTRL MO SWWD
INTO NW AR...ERN OK AND EAST TX. ALTHOUGH MODEL FORECASTS DIFFER
SLIGHTLY ON THE TIMING AND LOCATION OF INITIATION...CONCENSUS PLACES
THE INITIAL DEVELOPMENT IN THE WARM SECTOR OVER NERN OK...SE KS AND
WRN MO AROUND 03Z THIS EVENING. THIS SEEMS REASONABLE WITH A RAPID
INCREASE IN COVERAGE ALONG THE INSTABILITY AXIS FROM NNE TO SSW
DURING THE OVERNIGHT PERIOD. ANOTHER BAND OF CONVECTION APPEARS
LIKELY TO ORGANIZE ALONG A COLD FRONT ADVANCING SEWD ACROSS CNTRL OK
AND NCNTRL TX DURING THE 08Z TO 12Z TIMEFRAME.

CONCERNING THE SEVERE POTENTIAL...THE ERN EDGE OF A BROAD 80 TO 100
KT MID-LEVEL JET WILL MOVE EWD ACROSS THE SRN HIGH PLAINS AND CNTRL
PLAINS TODAY AND INTO THE SRN PLAINS AND OZARKS DURING THE OVERNIGHT
PERIOD. THIS WILL GRADUALLY INCREASE VERTICAL SHEAR PROFILES ACROSS
THE REGION WITH TIME. 0-6 KM SHEAR VALUES SHOULD RANGE FROM 60 TO 75
KT BY 06Z ACROSS MUCH OF THE WARM SECTOR. IN ADDITION...NAMKF
FORECAST SOUNDINGS DEVELOP A NARROW AXIS OF MODERATE INSTABILITY
FROM NEAR DALLAS/FORT WORTH NEWD TO SOUTHWEST OF SPRINGFIELD MO.
THIS ALONG WITH THE STRONG VERTICAL SHEAR SHOULD SUPPORT SUPERCELL
DEVELOPMENT WITH THE GREATEST THREAT AT THE BEGINNING OF THE EVENT
WHEN STORMS WILL HAVE THE BEST CHANCE TO REMAIN DISCRETE. 0-1 KM
SHEAR VALUES OF 25 TO 30 KT SHOULD BE ENOUGH FOR A TORNADO THREAT
WITH SUPERCELLS THAT DEVELOP ESPECIALLY WEST OF THE LOW-LEVEL JET
ACROSS ERN OK...FAR NW AR AND FAR SW MO. AS STORM COVERAGE RAPIDLY
INCREASES...THE DOMINANT MODE MAY BECOME LINEAR INSTEAD OF MULTICELL
LINE-SEGMENTS AS A SQUALL-LINE ORGANIZES AFTER MIDNIGHT. THIS ALONG
WITH 30 TO 40 KT OF FLOW JUST ABOVE THE SFC MAY TRANSLATE TO A WIND
DAMAGE THREAT AS THE LINE INTENSIFIES LATE IN THE PERIOD. ALTHOUGH
THE SQUALL-LINE MAY HAVE A THREAT FOR HAIL...THE GREATER THREAT FOR
HAIL MAY EXIST AS STORMS DEVELOP ALONG A COLD FRONT IN CNTRL OK AND
NCNTRL TX LATE WHERE MID-LEVEL LAPSE RATES MAY BE A BIT STEEPER.

FURTHER SOUTH ACROSS CNTRL AND EAST TX...LARGE-SCALE ASCENT IS NOT
FORECAST TO BE AS STRONG. THIS MAY HOLD CONVECTIVE INITIATION BACK
UNTIL AROUND 12Z. IF CONVECTION CAN INITIATE BY THE END OF THE
PERIOD...THE COMBINATION OF STRONG VERTICAL SHEAR AND MODERATE
INSTABILITY EVIDENT ON FORECAST SOUNDINGS SHOULD BE SUPPORTIVE OF AT
LEAST A MARGINAL WIND DAMAGE OR HAIL THREAT.

..BROYLES.. 12/26/2008

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[CrazyC83]

Tornado - 5%

Hail - 15%

Wind - 30%

Very difficult forecast, very similar to January 7.

[CrazyC83]

Saturday's threat increasing:

SPC AC 260600

DAY 2 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1200 AM CST FRI DEC 26 2008

VALID 271200Z - 281200Z

...THERE IS A SLGT RISK OF SVR TSTMS FROM THE LOWER OH VALLEY REGION
SSWWD INTO NERN TX/NRN LA/NRN AND WRN MS...

...SYNOPSIS...
A LARGE MID-LEVEL TROUGH WILL MOVE SLOWLY EWD ACROSS THE CENTRAL
THIRD OF THE CONUS THIS PERIOD...WHILE AN EMBEDDED
SHORTER-WAVELENGTH TROUGH MOVES QUICKLY NEWD FROM NM TO THE UPPER MS
VALLEY/UPPER GREAT LAKES REGION BY 28/12Z.

AT THE SURFACE...A FRONT SHOULD STRETCH FROM THE UPPER MS VALLEY
SSWWD INTO ERN OK/CENTRAL TX AT THE START OF THE PERIOD. A FRONTAL
WAVE IS PROGGED TO BEGIN DEEPENING OVER MO AROUND MIDDAY...AND THEN
SHOULD SHIFT NNEWD ALONG THE FRONT TO THE UPPER GREAT LAKES REGION
LATE. THE TRAILING FRONT IS EXPECTED TO SURGE EWD AS THE LOW
DEEPENS NEWD ALONG THE BOUNDARY...CROSSING THE MS/TN/OH VALLEYS AND
APPROACHING THE WRN APPALACHIANS THROUGH THE END OF THE PERIOD.

...LOWER OH/LOWER AND MID MS VALLEYS WWD TO ERN PARTS OF OK/TX...
SHOWERS AND THUNDERSTORMS ONGOING AT THE START OF THE PERIOD ALONG
THE FRONT FROM MO SSWWD ACROSS ERN OK INTO TX WILL PROGRESS EWD
THROUGH THE MORNING...ALONG WITH ACCOMPANYING SEVERE POTENTIAL.

LITTLE DESTABILIZATION IS FORECAST DURING THE DAY DESPITE THE MOIST
PRE-FRONTAL BOUNDARY LAYER IN PLACE ACROSS THE S CENTRAL CONUS...AS
VERY WEAK LAPSE RATES WILL SUPPORT GENERALLY LESS THAN 500 J/KG
MIXED-LAYER CAPE.

NONETHELESS...WITH FLOW VEERING WEAKLY FROM SLY TO SSWLY WHILE
STRENGTHENING QUICKLY WITH HEIGHT THROUGH THE LOWER
TROPOSPHERE...SHEAR WILL BE MORE THAN SUFFICIENT FOR UPDRAFT
ORGANIZATION/ROTATION. GIVEN THE LACK OF INSTABILITY...AND
LINGERING WARM AIR IN THE LOWER TROPOSPHERE WHICH WILL LIKELY
REQUIRE CONSIDERABLE ASCENT TO ERODE...IT APPEARS THAT MOST OF DEEP
CONVECTION WILL BE CONFINED TO THE FRONTAL ZONE -- AND THUS A
PRIMARILY LINEAR STORM MODE IS ANTICIPATED. SHEAR WILL CERTAINLY BE
SUFFICIENT FOR EMBEDDED ROTATION AND/OR BOWING SEGMENTS WITHIN THE
LARGER-SCALE LINE...AND THUS LOCALLY-ENHANCED AREAS OF SEVERE THREAT
WILL LIKELY EXIST. AGAIN HOWEVER...THE OVERALL THREAT SHOULD REMAIN
CONSTRAINED TO SOME EXTENT BY THE GENERAL LACK OF FAVORABLE
INSTABILITY. ATTM...WILL INTRODUCE A 30% SEVERE PROBABILITY ACROSS
AR/SERN MO AND VICINITY -- WITHIN THE LARGER SLIGHT RISK AREA...AS
THIS REGION SHOULD EXPERIENCE THE GREATEST POTENTIAL FOR DAMAGING
WINDS AND ISOLATED TORNADOES THROUGH THE AFTERNOON.

A FRONTAL SQUALL LINE SHOULD CONTINUE THROUGH THE OVERNIGHT
HOURS...AS THE BOUNDARY SURGES E OF THE MS VALLEY. HOWEVER...EXPECT
THE SEVERE THREAT TO STEADILY WANE OVERNIGHT...AS WEAKER INSTABILITY
SUGGESTS A SLOW DECREASE IN CONVECTIVE INTENSITY.

..GOSS.. 12/26/2008

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[Ed Mahmoud]

Tonight's late evening Tulsa forecast sounding from the 12Z NAM model looks rather favorable for Winter season tornadoes, with strong instability starting almost at the surface, and very strong low level shear.





NAM simulated radar imagery suggests quick consolidation into a squall line that looks entirely due to frontal forcing, with little or no near surface instability, but 50 to 70 knot winds below 850 mb level that might get pulled down despite the lack of surface instability just due to be so close to ground level, perhaps in more intense rain areas.

[CrazyC83]

SPC now has 10-hatched over parts of the Ozarks.

[CrazyC83]

NWS Springfield is going to have a conference call in about 15 minutes.

They performed better than the SPC on January 7 (which required risk-taking since that was also an extremely difficult forecast given the modest instability). They do seem to be more agressive again today. Although I do agree that there should be a moderate risk from about Muskogee to NE of Springfield, and the slight risk should be extended into Illinois.

[Ed Mahmoud]

New GFS shows storms this evening developing ahead of the front in the warm sector Eastern Oklahoma, Western Arkansas and Southwest Missouri late this evening. I'd suppose these would have the best chance of having tornadoes, being ahead of the front.


If these storms are surface based, they'd have a good chance of being tornadic, but despite good mid level instability, GFS looks to suggest a small stable layer near the surface. Typical NW Arkansas/SW Missouri sounding


Then more heavy storms follow a few hours later right on the front, and these look like the heavy rain and wind damage storms.


Late in the afternoon, ahead of the squall line, GFS joins the NAM is showing no surface instability, but very strong winds just off the deck, which I suspect will get pulled down despite stable surface. Memphis should be just ahead of the squall line late tomorrow afternoon.

[CrazyC83]

1630Z update delayed - must be some discussion going on among the SPC mets. Delays are common when there is uncertanty as there are probably some calling for an upgrade to moderate based on MUCH greater than expected moisture return while others are sticking to the models with lower instability.

[CrazyC83]

1630Z: Remaining a slight risk for now, extended slightly northward

[CrazyC83]

SPC AC 261643

DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1043 AM CST FRI DEC 26 2008

VALID 261630Z - 271200Z

...THERE IS A SLGT RISK OF SVR TSTMS FROM THE SRN PLAINS INTO THE
LOWER MO VALLEY...

...SYNOPSIS...
12Z UPPER AIR DATA AND SATELLITE IMAGERY INDICATE SRN PART OF THE
FULL-LATITUDE UPPER TROUGH OVER THE WRN STATES IS CONTINUING TO DIG
SEWD ACROSS THE SRN NV/SWRN UT/NWRN AZ REGION...AS STRONG MID/UPPER
LEVEL JET STREAK PROGRESSES SWD ALONG THE CENTRAL CA COAST. THE
SYSTEM IS EXPECTED TO TURN MORE EWD BY TONIGHT...WITH THE TROUGH
EXTENDING FROM THE NRN PLAINS INTO THE SRN ROCKIES BY THE END OF THE
PERIOD. PRIMARY MID/UPPER LEVEL JET STREAK IS FORECAST TO EXTEND
FROM THE SRN HIGH PLAINS INTO THE CENTRAL PLAINS BY THIS TIME...AS
THE MAIN VORTICITY MAX MOVES EWD ACROSS NM.

AT THE SURFACE...LOW OVER NERN CO IS FORECAST TO MOVE NEWD TOWARD
THE UPPER MS VALLEY BY LATER TONIGHT. THE COLD FRONT EXTENDING SWWD
FROM THE LOW ACROSS NWRN NM/SERN AZ IS EXPECTED TO MOVE EWD INTO THE
CENTRAL AND SRN PLAINS TONIGHT. DEVELOPING DRY LINE ON THE WRN EDGE
OF LOW LEVEL MOISTURE RETURN IS EXPECTED TO PERSIST FROM S CNTRL KS
AND WRN OK SWD INTO TX...BEFORE THE ADVANCING COLD FRONT OVERTAKES
THE DRYLINE FROM NORTH-TO-SOUTH TONIGHT. THIS WILL PROVIDE THE
PRIMARY FOCUS FOR THUNDERSTORM DEVELOPMENT.

...SRN PLAINS INTO LOWER MO VALLEY...
MOISTURE CONTINUES TO RETURN NWD ACROSS THE SRN PLAINS INTO THE
CENTRAL PLAINS...WITH MID 60S DEW POINTS ACROSS CENTRAL/ERN TX AND
NEAR 60 DEGREE DEW POINTS AS FAR NORTH AS THE KS/OK BORDER. THE
MOISTURE RETURN IS EXPECTED TO CONTINUE AHEAD OF THE COLD FRONT/DRY
LINE INTO TONIGHT WITH 55-60 DEGREE DEW POINTS SPREADING INTO ERN KS
AND NRN MO BY 03-06Z. ALTHOUGH COLDER MID LEVEL TEMPERATURES AND
STEEPER LAPSE RATES WILL LAG TO THE WEST OF THE WARM SECTOR AND
WIDESPREAD CLOUD COVER MAY INHIBIT DIURNAL HEATING...INCREASING
MOISTURE WILL CONTRIBUTE TO DESTABILIZATION WITH MUCAPE OF 500-1000
J/KG DEVELOPING THROUGH THE MOIST AXIS THIS AFTERNOON AND TONIGHT.

A FEW THUNDERSTORMS MAY DEVELOP WITHIN THE WARM SECTOR OVER PARTS OF
NERN TX/ERN OK AND WRN AR THIS AFTERNOON AND EVENING. THIS AREA
WILL BE ALONG THE SRN EDGE OF STRONGER SWLY FLOW ALOFT AND ATTENDANT
DEEP LAYER SHEAR...SUGGESTING POTENTIAL FOR ISOLATED SEVERE STORMS.
HOWEVER...PRIMARY THUNDERSTORM DEVELOPMENT IS LIKELY TO BE DELAYED
UNTIL TONIGHT WHEN THE COLD FRONT MOVES INTO THE WRN EDGE OF THE LOW
LEVEL MOISTURE/INSTABILITY AXIS. MORE WIDESPREAD COVERAGE OF
STRONG/SEVERE STORMS IS LIKELY TO OCCUR FROM PARTS OF WRN MO INTO
ERN KS INITIALLY...WITH ACTIVITY DEVELOPING SWD ALONG THE COLD
FRONT/DRY LINE MERGER ACROSS OK INTO NRN TX THROUGH THE OVERNIGHT
HOURS. DISCRETE SUPERCELLS WILL BE POSSIBLE...ESPECIALLY EARLY IN
THE STORMS LIFE CYCLES...AS UPDRAFTS WILL BE EMBEDDED WITHIN
FAVORABLE LOW- AND DEEP-LAYER VERTICAL SHEAR. THESE STORMS WILL
HAVE POTENTIAL TO PRODUCE TORNADOES...DAMAGING WIND GUSTS...AND
OCCASIONAL HAIL. STRONG/SEVERE STORMS ARE EXPECTED TO SPREAD
EWD/NEWD THROUGH THE LATE NIGHT HOURS WITH THE CONVECTIVE MODE
TRANSITIONING TO QUASI-LINEAR STRUCTURES CONTAINING EMBEDDED BOW
ECHOES AND ISOLATED SUPERCELLS.

..WEISS.. 12/26/2008

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[Ed Mahmoud]

DFW- Best action should be just across the Red River in Oklahoma, and the likelihood the storms hit around dawn, when the planetary boundary layer may be decoupled, further reduces the tornado risk. But excellent instability (for December) and low level wind fields (for any time of year) means if any discrete cells just ahead of the front can root into the boundary layer, means an isolated tornado or two can't be ruled out, and as the co-location of SPC's 10% tornado risk and 10% significant tornado risk implies just across the River, with such strong low level winds, any tornadoes that do form would likely be strong.
Note total totals, an indication of mid-level (850 to 500 mb) instability from both NAM and GFS near 55, an indication of very strong mid level instability and maybe hail.



GFS



NAM

[CrazyC83]

SPC AC 261734

DAY 2 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1134 AM CST FRI DEC 26 2008

VALID 271200Z - 281200Z

...THERE IS A SLGT RISK OF SVR TSTMS FROM PORTIONS OF THE SRN PLAINS
ENEWD INTO THE LOWER MS TO MID MS/LOWER OH VALLEYS...

...SYNOPSIS...
MODELS ARE IN GOOD AGREEMENT...BUT HAVE ALSO CONTINUED TO TREND
SLOWER WITH THE EWD PROGRESSION OF THE DEEP WRN TROUGH DURING THE
DAY 1 PERIOD. THIS WILL RESULT IN A WWD EXTENSION OF THE SLIGHT
RISK AREA INTO ERN/SRN OK AND MUCH OF ERN AND NRN TX. DURING THE
DAY 2 PERIOD THE DEEP UPPER TROUGH WILL LIFT NEWD ACROSS THE CENTRAL
U.S. AS STRONGER FLOW ALOFT TRANSLATES INTO THE ERN PERIPHERY OF
THIS SYSTEM. A FAIRLY POTENT SHORT WAVE TROUGH EXPECTED TO BE
LOCATED...WITHIN THE BASE OF THE AFOREMENTIONED LONG WAVE TROUGH...
OVER NM AT 12Z SATURDAY WILL TRACK NEWD ACROSS OK/CENTRAL PLAINS AND
BECOME NEGATIVELY TILTED AND DEEPEN AS THIS FEATURE APPROACHES THE
UPPER MS VALLEY/WRN GREAT LAKES LATE SATURDAY NIGHT. THIS UPPER
FLOW PATTERN EVOLUTION WILL OCCUR AS HEIGHTS REMAIN HIGH ALONG THE
ERN SEABOARD AND HEIGHTS RISE FROM CA INTO THE ROCKIES IN RESPONSE
TO A LARGE UPPER LOW/TROUGH MOVING SWD FROM AK INTO THE NERN
PACIFIC.

AT 12Z SATURDAY...A COLD FRONT IS EXPECTED TO EXTEND FROM THE UPPER
MS VALLEY SWWD THROUGH ERN KS TO A SURFACE LOW OVER CENTRAL OK AND
THEN TRAIL SWWD THROUGH CENTRAL/SW TX. THE OK LOW WILL DEVELOP NEWD
ALONG THE SURFACE BOUNDARY REACHING NRN IL BY EARLY SATURDAY
EVENING. THIS SYSTEM WILL THEN UNDERGO A STRONG DEEPENING PROCESS
AS THE LOW MOVES INTO LOWER MI IN RESPONSE TO THE DEEPENING/NEGATIVE
TILT OF THE ASSOCIATED SH0RT WAVE TROUGH. THE SRN EXTENT OF THE
COLD FRONT IS FORECAST TO SPREAD EWD FROM THE SRN PLAINS TO THE
LOWER MS VALLEY ON DAY 2...WHILE THE NRN EXTENT IS EXPECTED TO SURGE
EWD FROM THE MID MS VALLEY THROUGH MUCH OF THE OH/TN VALLEYS
SATURDAY NIGHT INTO EARLY SUNDAY MORNING.

...SEVERE STORM EVENT IS EXPECTED TO BE ONGOING AT 12Z SATURDAY WITH
THE THREAT SPREADING EWD FROM SRN PLAINS TOWARD LOWER-MID MS
VALLEY...

...CENTRAL TX/SRN-ERN OK/AR/MO EWD TO LOWER-MID MS/LOWER OH
VALLEYS...
STRONG SSWLY LOW LEVEL FLOW AHEAD OF THE UPPER TROUGH WILL MAINTAIN
MOISTURE ADVECTION NWD ALONG AND E OF THE COLD FRONT WITH MID 50S
SURFACE DEWPOINTS REACHING INTO THE OH VALLEY...AND MID 60S
DEWPOINTS BEING MAINTAINED ACROSS CENTRAL TX TO THE ARKLATEX
SATURDAY MORNING/AFTERNOON...PRIOR TO THE COLD FRONT PASSAGE.

45-60 KT SSWLY LLJ BENEATH 70 KT SWLY MID LEVEL JET WILL RESULT IN A
FAVORABLE SHEAR ENVIRONMENT AT THE START OF THE PERIOD TO MAINTAIN
AN ONGOING ORGANIZED SEVERE THREAT FROM PARTS OF NRN TX/ CENTRAL OK
INTO SERN KS/SWRN-SRN MO. MODELS SUGGEST INSTABILITY WILL BE
GREATEST /MUCAPE UP TO 800-1200 J/KG/ DURING THE MORNING TO EARLY
AFTERNOON FROM THE TX/OK INTO WRN AR/WRN LA. IF INSTABILITY IS
GREATER THAN CURRENTLY ANTICIPATED...THEN THIS PART OF THE SLIGHT
RISK AREA MAY REQUIRE AN UPGRADE TO A MODERATE RISK. STRONG LOW
LEVEL DIRECTIONAL/SPEED SHEAR /SFC-3 KM SRH RANGING FROM 300-500
M2/S2 ACROSS SWRN PART OF THE SLIGHT WILL PROVE FAVORABLE FOR
TORNADIC SUPERCELLS...WITH AN ADDITIONAL THREAT FOR DAMAGING WINDS
AND HAIL. A FEW MODELS SUGGEST A SECOND SURFACE WAVE MAY DEVELOP
EWD FROM SRN OK TO CENTRAL AR DURING THE FIRST HALF OF DAY
2...RESULTING IN A FAVORABLE TRACK FOR ATTENDANT TORNADOES GIVEN
MAXIMIZED LOW LEVEL CONVERGENCE AND BACK LOW LEVEL FLOW FOR STORM
ROTATION/TORNADO THREAT.

ELSEWHERE ACROSS THE SLIGHT RISK AREA...INSTABILITY IS EXPECTED TO
BE MUCH WEAKER WITH NWD EXTENT INTO MO TO LOWER OH VALLEY AND EWD
INTO THE LOWER MS VALLEY THROUGH THE PERIOD. HOWEVER...STRONG DEEP
LAYER WIND FIELDS NEARLY UNIDIRECTIONAL WITH HEIGHT SUGGESTS A
SQUALL LINE SHOULD DEVELOP AND SPREAD EWD WITH AN ATTENDANT THREAT
FOR MAINLY DAMAGING WINDS ALONG AND E OF THE FRONT. LOW LEVEL SHEAR
WILL...HOWEVER...MAY SUPPORT EMBEDDED SUPERCELLS WITH AN ATTENDANT
TORNADO THREAT...ESPECIALLY EWD INTO PARTS OF LA NWD TO SRN MO.

AS COLD FRONT SWEEPS EWD SATURDAY NIGHT...DAMAGING WINDS SHOULD
BECOME THE PRIMARY EVENING AND EARLY OVERNIGHT THREAT INTO PARTS OF
MS AND POSSIBLY INTO THE LOWER OH VALLEY AS THE LOW LEVEL JET
STRENGTHENS TO 70-80 KT ACROSS THESE AREAS.

..PETERS.. 12/26/2008

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[somethingfunny]

Any ideas as to the timing of these storms crossing I-35/US 75? I'm hoping they'll wait until after midnight because I'm scheduled to be closing driver tonight.

At least this time, I know they're coming. The worst part of the tornado earlier this month was that it completely surprised me.

[CrazyC83]

Any ideas as to the timing of these storms crossing I-35/US 75? I'm hoping they'll wait until after midnight because I'm scheduled to be closing driver tonight.

At least this time, I know they're coming. The worst part of the tornado earlier this month was that it completely surprised me.

Probably around midnight or somewhat after, but it is hard to tell. I don't think Texas will be in the height of the activity though.

[somethingfunny]

Any ideas as to the timing of these storms crossing I-35/US 75? I'm hoping they'll wait until after midnight because I'm scheduled to be closing driver tonight.

At least this time, I know they're coming. The worst part of the tornado earlier this month was that it completely surprised me.

Probably around midnight or somewhat after, but it is hard to tell. I don't think Texas will be in the height of the activity though.

I live 3 miles south of the Red River. It's basically like living in Oklahoma, but with better neighbors. (no offence, EWG!)

[CrazyC83]

SPC AC 261958

DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0158 PM CST FRI DEC 26 2008

VALID 262000Z - 271200Z

...THERE IS A SLGT RISK OF SVR TSTMS FROM THE SRN PLAINS INTO THE
LOWER MO VALLEY...

...SRN PLAINS INTO LOWER MO VALLEY...
GIVEN SLOWER MODEL TRENDS IN EVENTUAL EWD PROGRESSION OF DIGGING
GREAT BASIN/SWRN STATES UPPER TROUGH TO THE SRN ROCKIES BY LATER
TONIGHT...AND WWD RETURN OF LOW LEVEL MOISTURE...THIS OUTLOOK HAS
EXTENDED THE SLIGHT RISK/SEVERE PROBABILITIES WWD ACROSS ERN KS AND
NORTH CENTRAL TX. THIS WWD TREND IN THE SEVERE WEATHER THREAT WAS
ALSO SUGGESTED BY THE 15Z SREF/NAMKF. TRENDS IN EARLY AFTERNOON
SURFACE ANALYSES INDICATED SURFACE DEWPOINTS IN THE MIDDLE 50S HAVE
ALREADY RETURNED NWD INTO WRN OK...CENTRAL KS /TO THE SE OF SLN/...
AND CENTRAL MO TO SRN IL...WHILE MID 60S DEWPOINTS HAVE NOW REACHED
THE ARKLATEX REGION.

THE LATEST NAMKF/SREF SUGGEST TSTMS MAY DEVELOP INITIALLY OVER THE
ARKLATEX REGION INTO ERN OK/WRN AR BY LATE AFTERNOON/EARLY EVENING
WITHIN CORRIDOR OF GREATEST MOISTURE RETURN. ADDITIONAL DEVELOPMENT
APPEARS MORE LIKELY OVER ERN KS/ADJACENT PARTS OF NRN OK EARLY THIS
EVENING /BY 03Z/ AS THE COLD FRONT/STRONGER LOW LEVEL FORCING
REACHES THE NWRN EXTENT OF MOISTURE RETURN. EFFECTIVE BULK SHEAR
ALONG SRN EXTENT OF STRENGTHENING SWLY FLOW ALOFT WILL SUPPORT AT
LEAST ISOLATED SEVERE STORMS..GIVEN WEAK INSTABILITY /MLCAPE AOA 500
J/KG/. HOWEVER...PRIMARY...MORE WIDESPREAD...TSTM DEVELOPMENT
SHOULD CONTINUE TO BE DELAYED UNTIL LATER THIS EVENING /AFTER 03-
06Z/ AS THE COLD FRONT PROGRESSES EWD INTO THE LOWER MO VALLEY AND
EVENTUALLY ALONG THE COLD FRONT/DRY LINE MERGER ACROSS OK INTO NRN
TX THROUGH THE OVERNIGHT HOURS

DISCRETE SUPERCELLS WILL BE POSSIBLE...ESPECIALLY EARLY IN THE
STORMS LIFE CYCLES...AS UPDRAFTS WILL BE EMBEDDED WITHIN FAVORABLE
LOW- AND DEEP-LAYER VERTICAL SHEAR. THESE STORMS WILL HAVE
POTENTIAL TO PRODUCE TORNADOES... DAMAGING WIND GUSTS...AND
OCCASIONAL HAIL. STRONG/SEVERE STORMS ARE EXPECTED TO SPREAD
EWD/NEWD THROUGH THE LATE NIGHT HOURS WITH THE CONVECTIVE MODE
TRANSITIONING TO QUASI-LINEAR STRUCTURES CONTAINING EMBEDDED BOW
ECHOES AND ISOLATED SUPERCELLS.

..PETERS.. 12/26/2008

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[Dave]

THE NATIONAL WEATHER SERVICE IN WILMINGTON HAS ISSUED A DENSE FOG ADVISORY...WHICH IS IN EFFECT UNTIL 9 PM THIS EVENING.

The above statement applies to SW OH & SE IN though most of Indiana from a line north of US 50 is also under the same advisory.

67 to 70 degrees for a high on saturday is not normal for us this time of year. Looks like it could be an interesting day.