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ACUS01 KWNS 060552
SWODY1
SPC AC 060549
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1249 AM CDT THU MAY 06 2004
VALID 061200Z - 071200Z
THERE IS A SLGT RISK OF SVR TSTMS TO THE RIGHT OF A LINE FROM 25 SSW
JFK ABE AOO HLG MIE DNV PIA OTM 45 W LWD BIE HSI GRI OFK FOD LNR 35
N MKG 30 SSE OSC ..CONT.. 30 WSW MSS 15 W MPV 10 ESE PSM.
GEN TSTMS ARE FCST TO THE RIGHT OF A LINE FROM 70 SSW GDP ALM 4CR 25
WNW TCC LHX CYS DGW SHR 10 SSE LVM 10 SE BTM LMT MFR RDM PDT 10 SSE
3TH GTF SDY BIS FAR HIB 125 NNE CMX ..CONT.. 50 WNW 3B1 3B1 15 E
BHB ..CONT.. 15 ESE NEL TTN CXY DCA 30 SSW NHK 30 WNW ECG FLO 35
NW CHS 40 ENE SAV SSI JAX GNV CTY MAI MGM AUO MCN AND PSK EKN PKB
DAY MTO UIN LWD CNK DDC PVW LBB 65 NNE ABI MWL ACT 10 SSE SAT 40 W
MFE.
...THERE IS A SLGT RISK OF SVR TSTMS FROM THE LWR GREAT LAKES REGION
INTO THE MID MISSOURI VALLEY....
SPLIT IN UPPER FLOW PATTERN WILL PERSIST ACROSS THE NORTHEAST
PACIFIC THROUGH THIS FORECAST PERIOD. DOWNSTREAM OF BLOCK OFF THE
PACIFIC NORTHWEST/BRITISH COLUMBIA COAST...MERGING BRANCHES OF
STRONGER WESTERLIES WILL REMAIN GENERALLY ZONAL...EXTENDING EASTWARD
NEAR/JUST NORTH OF THE CANADIAN U.S. BORDER.
INTENSE MID/UPPER JET STREAK AND ASSOCIATED LOW AMPLITUDE WAVE ARE
EMBEDDED WITHIN THIS REGIME...AND PROGGED TO SHIFT OUT OF THE
CENTRAL INTO THE EASTERN CANADIAN PROVINCES. AS THIS
OCCURS...LOW-LEVEL BAROCLINIC ZONE WILL TIGHTEN IN EAST-WEST BAND
AND SHIFT SOUTHWARD ACROSS THE NORTH CENTRAL/NORTHEASTERN STATES.
BY LATE THURSDAY NIGHT/EARLY FRIDAY...FRONTAL ZONE WILL EXTEND FROM
NEW ENGLAND INTO THE MID MISSOURI VALLEY AND CENTRAL HIGH PLAINS.
THIS FEATURE IS EXPECTED TO BECOME FOCUS FOR EXTENSIVE CONVECTIVE
DEVELOPMENT THROUGH THIS PERIOD...SOME OF WHICH WILL BE SEVERE...
PRIMARILY WITH DAMAGING WIND GUSTS AND LARGE HAIL.
...GREAT LAKES REGION...
INCREASING CONVERGENCE/ISENTROPIC ASCENT AHEAD OF SURFACE FRONT IS
EXPECTED TO CONTRIBUTE TO MOISTENING/DESTABILIZATION THROUGH THE
DAYTIME HOURS FROM SOUTHERN LOWER MICHIGAN INTO NEW YORK STATE. MEAN
MIXED LAYER CAPE OF 1000 TO 2000 J/KG APPEARS LIKELY TO DEVELOP...AS
CAP SUPPRESSES CONVECTION EARLY AND ALLOWS A SUBSTANTIAL AMOUNT OF
SURFACE HEATING. ALTHOUGH THERE ARE SOME DISCREPANCIES...MODELS
GENERALLY SUGGEST AREA OF STRONGER FORCING FOR UPWARD VERTICAL
MOTION WILL OVERSPREAD LOWER MICHIGAN AROUND/SHORTLY AFTER PEAK
HEATING. THIS WILL BE IN ASSOCIATION WITH ZONE OF ENHANCED
LOW-LEVEL WARM ADVECTION BENEATH DIFLUENT UPPER FLOW FIELD...JUST
AHEAD OF BASE OF LOW AMPLITUDE TROUGH WHICH WILL SPREAD EAST OF THE
LOWER GREAT LAKES REGION TONIGHT.
GIVEN POTENTIAL INSTABILITY AND LARGE-SCALE FORCING...POTENTIAL
EXISTS FOR EVOLUTION OF FAIRLY SUBSTANTIAL MESOSCALE CONVECTIVE
SYSTEM. RISK OF DAMAGING WIND GUSTS WILL BE ENHANCED BY 40 TO 50 KT
WESTERLY MEAN FLOW ENVIRONMENT...AND MAY PERSIST THROUGH THE EVENING
INTO THE OVERNIGHT HOURS AS ACTIVITY PROGRESSES EAST OF THE LOWER
LAKES INTO THE HUDSON VALLEY.
...UPPER MISSISSIPPI VALLEY INTO THE MID MISSOURI VALLEY...
WIDELY SCATTERED STRONG/SEVERE THUNDERSTORMS MAY BE ONGOING AT
06/12Z...JUST TO COOL SIDE OF SURFACE FRONTAL ZONE FROM PARTS OF
NORTHERN IOWA/SOUTHERN MINNESOTA INTO WISCONSIN. THIS ACTIVITY IS
EXPECTED TO DEVELOP EASTWARD/DIMINISH DURING THE DAY...WITH FRONTAL
ZONE ADVANCING SOUTHWARD ACROSS NORTHERN ILLINOIS/SOUTHERN
IOWA/SOUTHERN NEBRASKA.
MID-LEVEL CAP MAY SUPPRESS CONVECTION ALONG FRONT THROUGH MOST OF
THE DAY. HOWEVER...LOW-LEVEL JET IS PROGGED TO PERSIST IN
ANTICYCLONIC ARC ACROSS THE CENTRAL PLAINS INTO VICINITY OF FRONT.
ISENTROPIC ASCENT OF HEATED BOUNDARY LAYER AIR NORTH OF FRONTAL ZONE
MAY SUPPORT NEW CONVECTIVE DEVELOPMENT BY LATE AFTERNOON ACROSS
SOUTHERN IOWA/NORTHERN ILLINOIS. LARGE HAIL SHOULD BE PRIMARY THREAT
WITH THIS ACTIVITY...WHICH MAY PERSIST THROUGH THE EVENING
HOURS...WHILE DEVELOPING UPSTREAM ALONG INTENSIFYING LOW-LEVEL JET
AXIS INTO EASTERN NEBRASKA.
...MID/SOUTH ATLANTIC COAST STATES...
UPPER FORCING WILL BE WEAK BENEATH SUBTROPICAL RIDGE.
HOWEVER...BOUNDARY LAYER WILL REMAIN MOIST ENOUGH...THAT WITH STRONG
SURFACE HEATING/WEAK WARM ADVECTION...WIDELY SCATTERED THUNDERSTORM
ACTIVITY WILL DEVELOP NEAR SURFACE TROUGH IN THE LEE OF THE
APPALACHIANS.
...SOUTHERN HIGH PLAINS/WEST TEXAS...
WEAK UPPER TROUGH IN SUBTROPICAL WESTERLIES MAY CONTRIBUTE TO
SCATTERED THUNDERSTORM ACTIVITY ACROSS PARTS OF EASTERN NEW
MEXICO/WEST TEXAS. THOUGH MID/UPPER FLOW FIELD WILL BE QUITE
WEAK...SHEAR PROFILES ARE PROGGED TO BECOME MODERATE IN STRENGTH ON
SOUTHWESTERN PERIPHERY OF CLOSED MID-LEVEL CIRCULATION...WHERE
SOUTHEASTERLY LOW-LEVEL FLOW WILL VEER TO NORTHWESTERLY AT
MID-LEVELS. THIS MAY ENHANCE RISK OF AN ISOLATED SEVERE STORM OR
TWO NEAR DRY LINE...MAINLY SOUTH/EAST OF THE FORT STOCKTON AREA.
...NORTHWESTERN U.S...
LOW/MID-LEVEL BAROCLINIC ZONE MAY BECOME FOCUS FOR WIDELY SCATTERED
THUNDERSTORMS FROM THE LEE OF THE SOUTHERN CASCADES INTO THE
NORTHERN ROCKIES...THOUGH LACK OF BETTER MOISTURE WILL LIMIT THIS
THREAT. BEST POTENTIAL FOR LATE AFTERNOON/EVENING CONVECTIVE
DEVELOPMENT APPEARS TO EXIST ACROSS PARTS OF CENTRAL/NORTHEAST
OREGON...BENEATH DIFLUENT UPPER FLOW REGIME DOWNSTREAM OF CLOSED LOW
OFF THE PACIFIC NORTHWEST COAST.
..KERR.. 05/06/2004
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521
ACUS02 KWNS 060752
SWODY2
SPC AC 060750
DAY 2 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0250 AM CDT THU MAY 06 2004
VALID 071200Z - 081200Z
THERE IS A SLGT RISK OF SVR TSTMS TO THE RIGHT OF A LINE FROM 35 NNE
ORF 25 SE UNI 15 SSW DNV 35 SSW OTM 10 NE FNB 20 W LNK 15 W SUX 30
ENE OTG 40 NNE RST 15 NE MTC.
GEN TSTMS ARE FCST TO THE RIGHT OF A LINE FROM 20 WSW ERI ACY.
GEN TSTMS ARE FCST TO THE RIGHT OF A LINE FROM 35 N HVR 50 WSW DIK
55 NNE RAP 40 WSW RAP 30 SE SHR 35 SSW COD 30 SSE TWF 30 N BAM 65
NNW LOL 35 SE LMT 55 N MFR 25 WNW SLE CLM.
GEN TSTMS ARE FCST TO THE RIGHT OF A LINE FROM 75 S MRF 15 N ROW 15
ENE TAD 40 W IML 40 NNE ANW 30 SE AXN 45 S IMT 85 ENE OSC ..CONT..
20 NW ART 25 SSE PSM ..CONT.. 20 E ORF 40 SSW IRK 10 SSE MHK 25 SE
DDC 45 NNW CDS 50 WSW SJT 45 ESE P07.
...THERE IS A SLGT RISK OF SVR TSTMS MID MO RIVER VALLEY INTO THE
GREAT LAKES AND MID ATLANTIC...
...MID MO RIVER VALLEY INTO THE GREAT LAKES AND MID ATLANTIC...
PATTERN WILL REMAIN ACTIVE FOR SEVERE THUNDERSTORMS ON FRIDAY AND
FRIDAY NIGHT AS QUASI-STATIONARY FRONT PARALLELS MODERATE MID AND
UPPER LEVEL FLOW FROM THE MID ATLANTIC COAST INTO THE MID MO RIVER
VALLEY. A SERIES OF FAST MOVING SHORTWAVE TROUGHS WILL SHIFT EWD
ATOP BROAD RIDGE AXIS AND ENHANCE CONVECTIVE POTENTIAL ALONG AND
NORTH OF THIS FRONT THROUGH THE PERIOD. LEADING SYSTEM WILL AID IN
PUSHING SURFACE FRONT SSEWD AS A COLD FRONT THROUGH THE FIRST HALF
OF THE PERIOD INTO THE MID ATLANTIC/CHESAPEAKE REGION. ANOTHER
SHORTWAVE TROUGH WILL SHIFT EWD ACROSS THE CENTRAL PLAINS LATE IN
THE DAY/OVERNIGHT LIFTING SURFACE FRONT SLOWLY NWD OVER INTO NRN
IL/IA AFTER DARK...AND INCREASE CONVECTION ALONG NOSE OF RESPONDING
SSWLY LLJ.
CONVECTION MAY BE ONGOING OVER THE SRN/ERN GREAT LAKES EARLY IN THE
PERIOD WHICH SHOULD DIMINISH DURING THE MORNING. CAPPING WILL AGAIN
BE A HINDRANCE FOR SURFACE-BASED STORMS DURING THE AFTERNOON ACROSS
MUCH OF THE REGION. EXCEPTION WILL BE IN THE SRN MID
ATLANTIC/CHESAPEAKE REGIONS...AS AIR MASS BECOMES MODERATELY
UNSTABLE WITHIN WARM SECTOR AHEAD OF SSEWD MOVING COLD FRONT. THIS
MAY SUPPORT A THREAT OF A FEW SEVERE THUNDERSTORMS ALONG ERN PORTION
OF THE FRONT DURING THE DAY. ANY CONVECTION WHICH CAN BREAK THE CAP
FARTHER WEST ALONG THE FRONT WILL ALSO CARRY WITH IT A THREAT OF
SEVERE. PRIMARY SEVERE THREAT MAY DEVELOP LATER IN THE DAY/EVENING
INTO IA/SRN WI/NRN IL ALONG NOSE OF INCREASING SWLY LLJ...WHICH
MIGHT REMAIN ELEVATED NORTH OF THE SURFACE FRONT. THIS ACTIVITY
WILL SHIFT EWD INTO THE CENTRAL/SRN GREAT LAKES REGION OVERNIGHT IN
THE FORM OF ONE OR MORE MCS/S. VERY STEEP LAPSE RATES...MODERATE
MUCAPE AND SUFFICIENT CLOUD LAYER SHEAR FOR ROTATING UPDRAFTS
SUGGEST THESE STORMS WILL LIKELY PRODUCE LARGE HAIL. SHOULD
DEVELOPMENT BECOME ROOTED NEAR THE SURFACE FRONT...BOW ECHO/ISOLATED
TORNADO THREAT WOULD ALSO INCREASE.
...CENTRAL AND SRN HIGH PLAINS...
HEATING AND DEEP MIXING ALONG DRY LINE WILL WEAKEN CAP OVER THE HIGH
PLAINS LATE FRIDAY...AND SUGGESTS ONE OR MORE CLUSTERS OF
THUNDERSTORMS MAY FORM AND SHIFT SLOWLY EWD INTO THE EARLY EVENING
BEFORE DIMINISHING. SHEAR REMAINS WEAK AND WILL LIMIT ORGANIZATION
OF ANY THUNDERSTORMS. HOWEVER...VERY STEEP LAPSE RATES DUE TO
STRONG HEATING AND RELATIVELY COOL MID LEVEL TEMPERATURES SUGGEST
LOW PROBABILITIES OF SEVERE HAIL/WIND ARE WARRANTED.
...NRN INTERMOUNTAIN INTO THE NRN ROCKIES/ADJACENT PLAINS...
UPPER LOW WILL CONTINUE TO SLOWLY DRIFT TOWARDS THE PAC NW
FRIDAY...WITH A SERIES OF WEAKER SHORTWAVE TROUGHS EJECTING NEWD
ACROSS THIS REGION ENHANCING THE POTENTIAL FOR THUNDERSTORMS. IN
ADDITION...SURFACE TO H7 COLD FRONT IS FORECAST TO SPREAD EWD INTO
THE NRN INTERMOUNTAIN REGION DURING THE AFTERNOON AND MAY FOCUS
MOIST CONVECTION INTO ERN ORE/SERN WA AND WRN ID. APPEARS LAPSE
RATES WILL BECOME QUITE STEEP UNDER PLUME OF MID LEVEL MOISTURE
OVERSPREADING THE REGION ...WITH MARGINAL INSTABILITY DEVELOPING.
THIS MIGHT SUPPORT A FEW STRONG TO MARGINALLY SEVERE...
THUNDERSTORMS DURING THE LATE AFTERNOON AND EARLY EVENING.
..EVANS.. 05/06/2004
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SPC AC 060948
DAY 3 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0448 AM CDT THU MAY 06 2004
VALID 081200Z - 091200Z
...THERE IS A SLGT RISK OF SVR TSTMS FROM THE NRN/CENTRAL PLAINS TO
THE MID ATLANTIC...
...SYNOPSIS...
MODELS IN AGREEMENT IN BRINGING SIGNIFICANT SHORTWAVE TROUGH ACROSS
THE CENTRAL PLAINS SATURDAY...SUPPRESSING TOP OF RIDGE AND LIKELY
BREAKING PERSISTENT CAPPING OVER THE CENTRAL PLAINS AND MID MO RIVER
VALLEY DURING THE AFTERNOON/EVENING. SURFACE LOW WILL LIKELY
DEVELOP IN RESPONSE TO THIS SYSTEM OVER THE CENTRAL PLAINS...WITH
WARM FRONT EXTENDING FROM IA ESEWD INTO THE DELMARVA AND A LEE
TROUGH/DRY LINE MIXING EWD INTO CENTRAL NEB/WRN KS/WRN TX.
...CENTRAL PLAINS INTO WRN GREAT LAKES...
AIR MASS WILL LIKELY BECOME VERY UNSTABLE WITHIN WARM SECTOR...WITH
MLCAPES IN EXCESS OF 2000 J/KG...BY THE MID LATE/AFTERNOON. EXPECT
CAP WILL BREAK AND SUPPORT RAPID SEVERE THUNDERSTORM DEVELOPMENT
ALONG SURFACE FRONT AND DRY LINE OVER THE CENTRAL PLAINS SATURDAY
AFTERNOON. SHEAR AND SUPERCELL POTENTIAL WILL BE GREATER INTO
NEB/WRN IA. FARTHER SW...ACTIVITY MAY BE ABLE TO ORGANIZE OVER WRN
KS AND SUPPORT LARGE HAIL/DAMAGING WINDS FROM HIGH-BASED STORMS
GIVEN 20-30 KT OF DEEP LAYER SHEAR.
ACTIVITY WILL CONTINUE INCREASING IN COVERAGE THROUGH THE EVENING
ALONG NOSE OF LLJ ACROSS THE MID MO/NRN MS RIVER VALLEYS AND SPREAD
ACROSS THE WRN GREAT LAKES OVERNIGHT...LIKELY IN THE FORM OF ONE OR
MORE SEVERE MCS/S. APPEARS SEVERE THREAT MAY BECOME WIDESPREAD LATE
SATURDAY AND CONTINUE THROUGH THE EVENING...WITH POTENTIAL FOR
SIGNIFICANT HAIL/WIND ALONG WITH A FEW TORNADOES. AREA MAY NEED
UPGRADE TO MODERATE IN LATER OUTLOOKS.
...SRN/CENTRAL GREAT LAKES INTO THE DELMARVA...
SURFACE FRONT WILL REMAIN IN PLACE ACROSS THIS REGION THROUGH THE
PERIOD AND BE PARALLEL TO MODEST WLY MID/UPPER LEVEL FLOW.
NOCTURNAL MCS/S WILL LIKELY CONTINUE ALONG AND NORTH OF THE
FRONT...WITH ISOLATED SEVERE. DIURNAL HEATING AND CONVERGENCE WILL
ALSO LIKELY SUPPORT SEVERE THUNDERSTORM DEVELOPMENT ALONG THE
BOUNDARY BY THE MID AFTERNOON...WITH SUFFICIENT SHEAR FOR SUPERCELLS
AND BOW ECHOES AS STORMS MOVE ESEWD ALONG THE FRONT INTO THE EARLY
EVENING.
...NRN PLAINS...
SHORTWAVE TROUGH EJECTING AWAY FROM PAC NW UPPER LOW WILL MOVE
ACROSS THE NRN PLAINS LATE IN THE DAY/OVERNIGHT. THIS MAY SUPPORT A
FEW SEVERE THUNDERSTORMS ALONG ASSOCIATED SURFACE TROUGH/COLD FRONT
MOVING EWD ACROSS THIS REGION...SHOULD SUFFICIENT BOUNDARY LAYER
MOISTURE BE IN PLACE. WILL OPT TO ONLY FORECAST LOW PROBABILITIES
ACROSS THIS REGION ATTM...DUE TO UNCERTAINTY WITH THIS AREA.
...SRN HIGH PLAINS...
ISOLATED HAIL/WIND EVENTS MAY ACCOMPANY ANY CONVECTION WHICH CAN
DEVELOP ALONG THE DRY LINE ACROSS ERN NM/WRN TX SATURDAY AFTERNOON
AND EVENING. SHEAR WILL REMAIN WEAK...HOWEVER...AND LIMIT THREAT OF
ORGANIZED SEVERE.
..EVANS.. 05/06/2004
