[SWODY1] SWODY1

[SWODY1 at goshenarc.org]

ACUS01 KWNS 211622
SWODY1
SPC AC 211620

DAY 1 CONVECTIVE OUTLOOK  
NWS STORM PREDICTION CENTER NORMAN OK
1120 AM CDT SAT MAY 21 2005

VALID 211630Z - 221200Z

THERE IS A SLGT RISK OF SVR TSTMS TO THE RIGHT OF A LINE FROM CMX 35
E AUW DBQ 25 SW BRL 15 NNE TBN 10 SSE SGF 30 WNW JLN HUT 45 NNE DDC
15 NW HLC 25 NNW GRI 30 SW YKN ATY 15 W FAR 35 WSW GFK 45 N DVL.

GEN TSTMS ARE FCST TO THE RIGHT OF A LINE FROM 30 NE MSS 25 E ISP
...CONT... 20 SSE ORF 20 SSE CHO 25 E PIT 55 W BUF.

GEN TSTMS ARE FCST TO THE RIGHT OF A LINE FROM 25 WSW PNS 20 NNE
SSI.

GEN TSTMS ARE FCST TO THE RIGHT OF A LINE FROM ANJ 40 WSW SDF 25 NNW
DYR OKC 40 SW GAG EHA 15 SE IML 20 NNE ANW 20 N MBG 75 WNW MLS 50 NE
CTB.

...THERE IS A SLGT RISK OF SVR TSTMS CENTRAL PLAINS TO UPPER
MISSISSIPPI VALLEY...

...SYNOPSIS...
VIGOROUS UPPER TROUGHS MOVING IN THE STRONG FLOW ACROSS THE TOP OF
THE LARGE AREA OF HIGH PRESSURE OVER THE SWRN U.S. WHILE IMPRESSIVE
CYCLOGENESIS FOR MAY HAS OCCURRED OVERNIGHT OFF THE PAC NW
COAST...THE DOWNSTREAM SYSTEM ALSO IS INTENSIFYING AS IT TRACKS EWD
ALONG CANADIAN/NCENTRAL U.S. BORDER.  SURFACE LOW ASSOCIATED WITH
THIS TROUGH CURRENTLY OVER CENTRAL ND WILL DEEPEN NEWD INTO SRN
MANITOBA TODAY WITH TRAILING COLD FRONT NOW CENTRAL DAKOTAS/NWRN
NEB. WITH SUPPORT FROM A STRONG MID LEVEL JET MAX TO NEAR 90KT AT
500MB CROSSING ERN MT...THE FRONT WILL REACH THE WRN GREAT LAKES
SWWD INTO ERN NEB AND TRAILING WWD INTO ERN CO BY THIS EVENING.

COLD UPPER LOW VICINITY SRN NEW ENGLAND MOVES LITTLE THIS FORECAST
PERIOD.

...NE/IA/KS/MO...

MORNING SOUNDINGS CONFIRM THAT A SUBSTANTIAL CAP CURRENTLY ACROSS
THE PLAINS AS ELEVATED MIX LAYER HAS SPREAD EWD OVERNIGHT WITH VERY
STEEP MID LEVEL LAPSE RATES.  50KT LOW LEVEL JET AHEAD OF COLD FRONT
WILL RAPIDLY INCREASE LOW LEVEL MOISTURE NWD THRU CENTRAL PLAINS
THIS AFTERNOON.  WHILE NAM SEEMS A LITTLE AGGRESSIVE ON MOISTURE
TRANSPORT...GIVEN THE OBSERVED DEWPOINTS RISING THRU THE 60S F
ACROSS CENTRAL KS...SUBSTANTIAL DESTABILIZATION IS EXPECTED AHEAD OF
COLD FRONT BY MID/LATE AFTERNOON AS FAR N AS ERN NEB/WRN IA. 
EROSION OF THE EXISTING STRONG CAP WILL TAKE PLACE THIS AFTERNOON
THRU STRONG SURFACE HEATING AND LARGE SCALE VERTICAL MOTION AHEAD OF
FRONT AND APPROACHING UPPER TROUGH.

BY LATE AFTERNOON WITH MLCAPES BETWEEN 2000-3000 J/KG COUPLED WITH
40-50 KT OF DEEP LAYER SHEAR...PARAMETERS WILL BE IN PLACE FOR RAPID
DEVELOPMENT OF SUPERCELL THUNDERSTORMS VICINITY OF COLD FRONT ERN
NEB.  TIMING OF INITIATION WILL BE VERY DEPENDENT ON HOW FAST THE
CAP ERODES...AND ATTM STORMS EXPECTED TO DEVELOP PRIOR TO SUNSET AND
POSSIBLY AS EARLY AS 22Z.  VERY LARGE HAIL TO BE PRIMARY THREAT WITH
ANY SUPERCELL...WHILE TORNADO POTENTIAL WILL BE SOMEWHAT MITIGATED
BY RELATIVELY HIGH LCL'S IN THE VERY WARM AIR MASS.

SEVERE STORMS WILL EVOLVE INTO A S/SEWD PROPAGATING MCS
OVERNIGHT...FEEDING ON THE CONTINUED NWD TRANSPORT OF UNSTABLE
AIRMASS THRU THE CENTRAL PLAINS.  DAMAGING WINDS WOULD LIKELY BECOME
PRIMARY THREAT OVERNIGHT INTO NERN KS/MO AS BOUNDARY LAYER
DECOUPLES.

...UPPER MS VALLEY...
STRONG COLD FRONT WILL CONTINUE EWD INTO WRN MN DURING AFTERNOON.
SUFFICIENT HEATING LOOKS TO TAKE PLACE AS OVERNIGHT MCS DEBRIS MOVES
ON TO THE E TO ALLOW FOR GOOD SURFACE HEATING INTO WRN MN. 
COMBINATION OF STRONG UPWARD MOTION AND HEATING...AGAIN THE STRONG
CAP THIS MORNING NOTED ON ABR SOUNDING SHOULD RAPIDLY ERODE ALLOWING
STORM INITIATION BY MID/LATE AFTERNOON ALONG THE COLD FRONT VICINITY
ND/MN BORDER.  WITH MLCAPES FROM 1000-1500 J/KG AND 50-60 KT OF DEEP
LAYER SHEAR...SUPERCELLS ARE LIKELY ONCE INITIATION OCCURS.  WHILE
THERE WILL BE LESS INSTABILITY THIS AREA...THE LOWER LCL'S AND
GREATER SHEAR SUPPORT AT LEAST POTENTIAL FOR ISOLATED TORNADOS ALONG
WITH A LARGE HAIL AND DAMAGING WIND THREAT.  STRONG FRONTAL FORCING
AND SHEAR EXPECTED TO RESULT IN A MORE LINEAR CONVECTION MODE DURING
EVENING...WITH DAMAGING WINDS BECOMING PRIMARY THREAT.


...MID ATLANTIC...
UPPER TROUGH EVIDENT ON WV IMAGERY OVER WRN NY/NWRN PA ASSOCIATED
WITH LOW OVER NEW ENGLAND WILL SWEEP SEWD ACROSS THE MID-ATLANTIC
TODAY. SFC AIRMASS DOWNSTREAM OF THIS TROUGH WILL GENERALLY BE
CHARACTERIZED BY TEMPERATURES IN THE 60S TO LOWER 70S AND DEWPTS IN
THE MID TO UPPER 40S. COLD MID LEVEL TEMPERATURES / -20 TO -24 DEG C
AT 500 MB / ABOVE THIS LOW LEVEL PROFILE WILL BE SUPPORTIVE OF
SUFFICIENT INSTABILITY...500 J/KG OF MUCAPE/ FOR THUNDERSTORMS
CAPABLE OF PRODUCING SMALL HAIL. 12Z RUC FCST SOUNDINGS SUGGEST A
NARROW CORRIDOR OF SLIGHTLY HIGHER DEWPTS IN THE LOWER-MID 50S OVER
NRN VA/MD AND DE DEVELOPING DURING THE AFTERNOON...WHILE BOTH THE
NAM AND NAMKF DO NOT SHOW THIS. IF THESE CONDITIONS DO INDEED
OCCUR...SLIGHTLY BETTER INSTABILITY /MUCAPES AROUND 1000 J/KG/ WOULD
SUPPORT A MARGINAL SVR HAIL THREAT AND SVR HAIL PROBABILITIES. 
HOWEVER ENOUGH UNCERTAINTY EXISTS THAT THESE WILL NOT BE INCLUDED
ATTM.

..HALES/CROSBIE.. 05/21/2005

...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.