Convective Storm outlook 5-26-04/NOAA Norman,Ok

[FWBHurricane]

VALID 271200Z - 281200Z

THERE IS A SLGT RISK OF SVR TSTMS TO THE RIGHT OF A LINE FROM 20 NNW
ROC ELM CXY WAL ...CONT... 25 S EWN RDU GSO HSS 30 S BNA 20 NNE FTW
60 NE P07 50 N BGS 20 NNE CDS LTS PNC EMP FLV DBQ 15 E JVL MBL 10
ENE APN.

GEN TSTMS ARE FCST TO THE RIGHT OF A LINE FROM 70 NE HVR MLS 4BQ 20
SSW CPR RKS DPG U31 20 NNW TVL RBL 35 WSW MHS 30 ENE PDX 20 ENE BLI.

GEN TSTMS ARE FCST TO THE RIGHT OF A LINE FROM 70 SSW P07 55 N MRF
GDP ELP 10 NNE SAD INW FMN RSL FNB MCW MSP IWD 130 NE CMX ...CONT...
20 NNE PBG ORH 35 W ACK ...CONT... 15 NNE CRE GSP CHA MSL PBF TXK
TPL 30 SSE DRT.

...THERE IS A SLGT RISK OF SVR TSTMS ACROSS PARTS OF THE MID MS/OH
VALLEYS AND SRN GREAT LAKES INTO MID ATLANTIC STATES...AS WELL AS
ACROSS PARTS OF THE SRN/CNTRL PLAINS....

LATEST MODEL RUNS ARE VERY SIMILAR WITH REGARD TO THE EVOLUTION OF
THE LARGE-SCALE UPPER FLOW PATTERN ACROSS THE NATION THROUGH THIS
FORECAST PERIOD. UPPER TROUGH NOW OVER THE GULF OF ALASKA/
NORTHEAST PACIFIC IS PROGGED TO AMPLIFY AND DIG SOUTHEASTWARD ACROSS
THE EASTERN PACIFIC INTO PACIFIC COAST STATES BY EARLY FRIDAY
MORNING. AS THIS OCCURS...A COUPLE OF SIGNIFICANT TROUGHS EMBEDDED
WITHIN DOWNSTREAM SPLIT BRANCHES OF STRONGER WESTERLIES WILL
ACCELERATE EASTWARD...LIKELY PROVIDING FORCING FOR A CONSIDERABLE
AMOUNT OF CONVECTIVE ACTIVITY IN MOIST UNSTABLE AIR MASS ACROSS THE
CENTRAL/EASTERN STATES.

...MISSISSIPPI VALLEY EASTWARD...
IN NORTHERN BRANCH OF WESTERLIES...BROAD TROUGH WITH EMBEDDED SHORT
WAVES WILL SHIFT EASTWARD ACROSS THE GREAT LAKES REGION.
CONSIDERABLE UNCERTAINTY EXISTS WITH REGARD TO DETAILS OF CONVECTIVE
DEVELOPMENT ASSOCIATED WITH THIS FEATURE. HOWEVER...STRONG
MID/UPPER JET IN BASE OF TROUGH...IN TANDEM WITH BROAD INTENSE
ANTICYCLONIC SOUTHERN STREAM JET...WILL CONTRIBUTE TO STRONGLY
SHEARED ENVIRONMENT FROM THE MID MISSISSIPPI VALLEY AND SOUTHERN
GREAT LAKES INTO THE MID ATLANTIC COASTAL AREAS. BOUNDARY LAYER WILL
REMAIN MOIST AND POTENTIALLY UNSTABLE...SUPPORTIVE OF INTENSE
CONVECTIVE DEVELOPMENT...BEFORE COLD FRONT SURGES INTO/THROUGH THE
OHIO VALLEY BY EARLY FRIDAY.

CONSIDERABLE CLOUD COVER AND THUNDERSTORM ACTIVITY ASSOCIATED WITH
LOWER/MID TROPOSPHERIC ISENTROPIC ASCENT APPEARS LIKELY TO SHIFT
EASTWARD THROUGH THE OHIO VALLEY INTO THE APPALACHIANS DURING THE
DAYTIME HOURS. THIS IS EXPECTED TO CLEAR AREAS FROM CENTRAL
ILLINOIS INTO SOUTHERN INDIANA IN TIME FOR SUBSTANTIAL DAYTIME
HEATING. MODELS SUGGEST AREA OF ENHANCED LOW-LEVEL ISENTROPIC
ASCENT COULD DEVELOP ALONG THIS AXIS BY LATE AFTERNOON...AS A
MID-LEVEL SHORT WAVE TROUGH SHIFTS ACROSS MICHIGAN/NORTHERN INDIANA
DURING THE PEAK HEATING HOURS. THIS IS EXPECTED TO BE SUPPORTIVE OF
ADDITIONAL CONVECTIVE DEVELOPMENT...WITH STORMS LIKELY QUICKLY
BECOMING ROOTED IN BOUNDARY LAYER WITH MEAN MIXED LAYER CAPE UP TO
AROUND 2000 J/KG. A FEW SEVERE STORMS APPEAR LIKELY...WITH VERTICAL
SHEAR PROFILES FAVORABLE FOR SUPERCELLS WITH LARGE HAIL/DAMAGING
WINDS...PERHAPS ISOLATED TORNADOES.

FURTHER CONVECTIVE DEVELOPMENT MAY OCCUR IN CLOSER PROXIMITY TO
SURFACE FRONT ACROSS NORTHERN INDIANA/SOUTHERN LOWER MICHIGAN...
WHERE FAVORABLE THERMODYNAMIC ENVIRONMENT AND SHEAR WILL SUPPORT
SEVERE POTENTIAL. ACTIVITY THROUGHOUT THE OHIO VALLEY WILL TEND TO
DEVELOP EAST SOUTHEASTWARD INTO THE EVENING HOURS...SLOWLY
DIMINISHING WITH LOSS OF DAYTIME HEATING AS IT PROGRESS INTO THE
APPALACHIANS AND AREAS SOUTH OF THE OHIO RIVER.

...SOUTHERN ROCKIES INTO SOUTHERN HIGH PLAINS...
SOUTHERN BRANCH CLOSED LOW IS PROGGED EASTWARD INTO NEW MEXICO
DURING THE AFTERNOON HOURS. THOUGH DRY LINE WILL BE FARTHER
EAST...ACROSS WEST TEXAS INTO WESTERN OKLAHOMA...MID-LEVEL COLD POOL
WITH 500 MB TEMPERATURES AOB -15C WILL CONTRIBUTE TO DESTABILIZATION
AS BOUNDARY LAYER HEATS ACROSS EASTERN NEW MEXICO.
THIS MAY SUPPORT A CONSIDERABLE AMOUNT OF HIGH-BASED CONVECTION WITH
POTENTIAL FOR GUSTY WINDS AND SOME HAIL.

AS 50+ KT SOUTHWESTERLY MID-LEVEL JET NOSES ACROSS WEST TEXAS...
FOLLOWED BY STRONGER MID-LEVEL HEIGHT FALLS...CONVECTION SHOULD
INITIATE AND QUICKLY BECOME SEVERE ALONG DRY LINE. MEAN MIXED LAYER
CAPE NEAR DRY LINE MAY EXCEED 2000 J/KG...AND GIVEN STRENGTH OF
MID/UPPER FLOW...A FEW SUPERCELLS ARE LIKELY. MODELS SUGGEST
LOW-LEVEL HODOGRAPHS WILL REMAIN FAIRLY WEAK...LIMITING TORNADO
THREAT...BUT ISOLATED BRIEF TORNADOES WILL BE POSSIBLE.

AS UPPER SYSTEM CONTINUES EASTWARD INTO THE LOWER PLAINS THURSDAY
EVENING...MID-LEVEL CAP WILL FINALLY WEAKEN. SUPPORTED BY
STRENGTHENING SOUTHERLY LOW-LEVEL JET...MID/UPPER FORCING APPEARS
FAVORABLE FOR EVOLUTION OF LARGE MESOSCALE CONVECTIVE SYSTEM ACROSS
OKLAHOMA AND PARTS OF NORTH CENTRAL TEXAS. RISK OF DAMAGING WINDS
WILL INCREASE AS SYSTEM EVOLVES...AND MAY PERSIST INTO THE OVERNIGHT
HOURS AS SYSTEM SLOWLY PROGRESSES EASTWARD.

..KERR.. 05/26/2004