[SWODY2] SWODY2

[SWODY2 at goshenarc.org]

ACUS02 KWNS 211732
SWODY2
SPC AC 211731

DAY 2 CONVECTIVE OUTLOOK  
NWS STORM PREDICTION CENTER NORMAN OK
1231 PM CDT THU APR 21 2005

VALID 221200Z - 231200Z

THERE IS A MDT RISK OF SVR TSTMS TO THE RIGHT OF A LINE FROM 45 WSW
OWB BMG DAY HTS 5I3 HSS AND MCN TOI 65 NW CEW LUL MLU ELD MEM 45 WSW
OWB.

THERE IS A SLGT RISK OF SVR TSTMS TO THE RIGHT OF A LINE FROM 40 NW
DRT 40 E BGS ABI MWL TXK LIT JBR MVN DEC 25 SSE PIA 30 NE BMI 25 NW
FWA 10 NNE FDY 15 SW CAK 25 S PIT EKN 10 WNW CHO 20 NNE RIC 10 ENE
WAL ...CONT... 25 NNE JAX 35 SE TLH.

GEN TSTMS ARE FCST TO THE RIGHT OF A LINE FROM 35 NE ROC UCA PWM
...CONT... 50 WNW DRT 25 E BGS 30 WNW TXK ARG BLV UIN IRK DSM RST
VOK 10 S OSH OSC.

GEN TSTMS ARE FCST TO THE RIGHT OF A LINE FROM 30 NE BLI 10 W EAT 10
NNW PDT BKE 60 W BOI 65 ESE 4LW 10 NNE MHS 4BK.

...THERE IS A MDT RISK OF SVR TSTMS FRI/FRI NIGHT ACROSS THE
CNTRL/ERN GULF STATES INTO THE TENNESSEE AND LWR OH VALLEY....

...THERE IS A SLGT RISK OF SVR TSTMS SURROUNDING THE MODERATE RISK
AREA...ACROSS MUCH OF THE SOUTHEASTERN U.S....

LATEST RUNS OF NAM/GFS APPEAR VERY SIMILAR WITH REGARD TO EVOLUTION
OF LARGE-SCALE PATTERN THROUGH THIS FORECAST PERIOD.  BLOCK WILL
PERSIST ACROSS THE EASTERN PACIFIC/WESTERN NORTH AMERICA. 
HOWEVER...MERGING NORTHERN AND SOUTHERN BRANCH SHORT WAVE TROUGHS
DOWNSTREAM ARE PROGGED TO CONTRIBUTE TO THE EVOLUTION OF A BROAD
DEEP CLOSED LOW EAST OF THE MISSISSIPPI VALLEY LATE FRIDAY INTO THE
WEEKEND.

THIS WILL BE ACCOMPANIED BY SURFACE CYCLOGENESIS ACROSS THE OHIO
VALLEY...WITH SERIES OF COLD FRONTAL INTRUSIONS INTO THE
CENTRAL/EASTERN STATES.  ULTIMATELY THIS WILL STABILIZE MUCH OF THE
NATION EAST OF THE ROCKIES.  BUT...BEFORE IT DOES...STRONG
LARGE-SCALE FORCING FOR UPWARD VERTICAL MOTION APPEARS LIKELY TO
SUPPORT WIDESPREAD CONVECTIVE DEVELOPMENT.

ENVIRONMENT OVER A BROAD AREA FROM THE GULF STATES INTO THE MIDDLE
MISSISSIPPI AND OHIO VALLEYS HAS MOISTENED CONSIDERABLY OVER THE
PAST SEVERAL DAYS.  AT THE SAME TIME...INCREASINGLY STEEP
LOW/MID-LEVEL LAPSE RATES DEVELOPING/SPREADING EAST OF THE PLAINS
ARE CONTRIBUTING TO INCREASINGLY FAVORABLE THERMODYNAMIC ENVIRONMENT
FOR SEVERE STORMS.  THIS WILL BE ENHANCED BY STRENGTHENING SHEAR
ASSOCIATED WITH EVOLVING UPPER PATTERN...AND A SUBSTANTIAL SEVERE
WEATHER OUTBREAK APPEARS POSSIBLE FRIDAY ACROSS MUCH OF THE MID
SOUTH AND SOUTHEAST STATES.

...CNTRL/ERN GULF STATES INTO TN/LWR OH VLYS...
MODELS SUGGEST INITIAL COLD SURGE...SOUTH AND WEST OF CENTRAL
ILLINOIS SURFACE LOW...WILL EXTEND ACROSS SOUTHEAST MISSOURI/CENTRAL
ARKANSAS INTO NORTHERN TEXAS BY 12Z FRIDAY.  MID-LEVEL DRY SLOT
APPEARS LIKELY TO OVERSPREAD WARM SECTOR EARLY IN THE DAY...WITH
BOUNDARY LAYER MOISTURE GRADIENT/DRY LINE TYPE BOUNDARY SETTING UP
ALONG PRE-FRONTAL WIND SHIFT FROM SOUTHWEST INDIANA THROUGH EASTERN
ARKANSAS BY MID DAY.  THIS FEATURE IS EXPECTED TO BECOME FOCUS FOR
INITIATION OF INTENSE CONVECTIVE DEVELOPMENT AS CAPE INCREASES IN
EXCESS OF 2000 J/KG.

ACTIVITY APPEARS POSSIBLE BY EARLY AFTERNOON...AS LEADING EDGE OF
FORCING ASSOCIATED WITH SOUTHERN BRANCH IMPULSE INTERACTS WITH
SURFACE BOUNDARY.  VERTICAL SHEAR PROFILES IN EXIT REGION OF 50 TO
70 KT CYCLONIC MID-LEVEL JET STREAK WILL BE SUPPORTIVE OF
SUPERCELLS...WITH POTENTIAL FOR VERY LARGE HAIL/DAMAGING WIND GUSTS.
 ISOLATED TORNADOES ARE ALSO POSSIBLE...BUT AT THE PRESENT TIME IT
APPEARS THIS THREAT COULD BE MITIGATED SOMEWHAT BY RELATIVELY SMALL
LOW-LEVEL HODOGRAPHS.

EVENTUALLY...CONVECTION IS EXPECTED TO EVOLVE INTO A SUBSTANTIAL
SQUALL LINE...OR PERHAPS A LARGE "BOWING" MESOSCALE CONVECTIVE
SYSTEM...AS IT SPREADS SOUTHEASTWARD TOWARD SOUTH ATLANTIC AND
EASTERN GULF COASTAL AREAS LATE FRIDAY/FRIDAY NIGHT.  THIS WILL BE
ACCOMPANIED BY POTENTIAL FOR WIDESPREAD DAMAGING WINDS.

...TEXAS...
MODELS SUGGEST HIGH-LEVEL RIDGE OVER THE SOUTHERN PLAINS EARLY IN
THE PERIOD WILL EVENTUALLY FLATTEN IN RESPONSE TO DEVELOPING SYSTEM
TO THE NORTHEAST.  THOUGH LOW/MID-LEVEL FLOW FIELDS ON ANTICYCLONIC
SIDE OF HIGH LEVEL JET WILL NOT BE PARTICULARLY
STRONG...LOW/MID-LEVEL THERMODYNAMIC ENVIRONMENT WILL REMAIN
SUPPORTIVE OF SEVERE STORMS WITH LARGE HAIL/DAMAGING DOWNBURSTS. 
ACTIVITY SHOULD DEVELOP SOUTHWARD WITH TIME AHEAD OF COLD FRONT...
FRONT CENTRAL INTO DEEP SOUTH TEXAS BY LATE FRIDAY NIGHT.

...PACIFIC NORTHWEST...
STRONG HEATING ALONG/IN THE LEE OF THE SOUTHERN CASCADES IS EXPECTED
TO CONTRIBUTE TO VERY STEEP LAPSE RATES BENEATH COLD POCKET
ASSOCIATED WEAKENING/WESTWARD PROPAGATING MID-LEVEL CIRCULATION. 
ISOLATED STRONG STORMS APPEAR POSSIBLE BY LATE AFTERNOON...A FEW OF
WHICH COULD BE ACCOMPANIED BY SOME HAIL APPROACHING OR BRIEFLY
EXCEEDING SEVERE LIMITS.

..KERR.. 04/21/2005

...NOTICE...
THE STATION RELATIVE POINTS IN THIS PRODUCT ARE NOW AVAILABLE
SEPARATELY UNDER THE WMO HEADINGS WUUS01 PTSDY1...
WUUS02 PTSDY2...WUUS03 PTSDY3.  THE INCLUSION OF POINTS
IN THIS DISCUSSION WILL BE DISCONTINUED AFTER THE 2005
CONVECTIVE SEASON.  A PUBLIC NOTIFICATION STATEMENT (PNS)
WILL PROVIDE DETAILS ON THE TRANSITION.