SPC Day 1 Thunderstorm Outlook Issued 13Z 20030709


ZCZC SPCSWODY1 ALL
ACUS01 KWNS 091315
SPC AC 091312

STORM PREDICTION CENTER...NWS/NCEP...NORMAN OK 
DAY 1 CONVECTIVE OUTLOOK...REF AWIPS GRAPHIC PGWE46 KWNS.

VALID 091300Z - 101200Z

THERE IS A MDT RISK OF SVR TSTMS ACROSS SERN AND ECNTRL IA...FAR
NERN MO...WCNTRL AND NWRN IL TO THE RIGHT OF A LINE FROM 40 SE IRK
25 SE P35 15 S LWD 25 NNW LWD 20 WSW DSM 20 NNE DSM 30 SSW ALO 30
NE CID 35 SE DBQ 45 WNW MMO 30 N BMI 20 SW BMI SPI 35 WSW SPI 25
SSE UIN 40 SE IRK.

THERE IS A SLGT RISK OF SVR TSTMS TO THE RIGHT OF A LINE FROM
45 NE UNO 15 WNW UMN PNC 35 ESE P28 20 N P28 40 S RSL 15 N RSL
55 WNW CNK 40 WNW BIE 15 WSW OMA 55 E SUX 35 SSE FRM 30 NNE MCW
35 SW LSE 20 ESE LNR 35 SSE SBN MIE 45 ESE IND 25 SSE BMG
30 ESE MVN 45 NE UNO.

GEN TSTMS ARE FCST TO THE RIGHT OF A LINE FROM 40 ESE DUG 65 NW TCS
30 SSE GNT 15 N SAF 30 NNW CAO 45 N EHA 40 NW GCK 50 WSW HLC
35 SE LBF 45 SSW ANW 35 NE VTN 30 NW Y22 60 N OLF ...CONT...
20 WNW RRT 35 NNW BJI 25 S HIB 25 E IWD 35 ESE ESC 20 SSW OSC
...CONT... 15 NW BUF 20 N BGM 20 SSW GON.

...SYNOPSIS...
UPPER-TROUGH OVER THE DAKOTAS WILL SHIFT SEWD TODAY AND SHOULD BE
ACROSS THE GREAT LAKES REGION BY LATE IN THE PERIOD. COLD FRONT
WILL ORGANIZE AND MOVE SEWD ACROSS THE CNTRL PLAINS AS A SYNOPTIC
LOW PRESSURE CENTER AND ASSOCIATED WARM FRONT LIFTS NEWD ACROSS THE
UPPER MIDWEST.

...IA/SRN MN/SW WI/IL/MO/ERN NEB/ERN KS...
ONGOING MCS ACROSS IA WILL COMPLICATE THINGS TODAY AS A LARGE COLD
POOL HAS BEEN LEFT BEHIND OVER ERN NEB/WRN IA. A WARM FRONTAL
BOUNDARY EXISTS ACROSS ERN IA/NRN IL WITH AN OUTFLOW BOUNDARY
EXTENDING ACROSS SRN IA INTO CNTRL IL. S OF THIS
BOUNDARY...ABUNDANT LOW-LEVEL MOISTURE EXISTS WITH SFC DEWPOINTS IN
THE LOWER 70S F. AS THE SFC LOW DEVELOPING ACROSS SRN-SERN NEB
MOVES NEWD TODAY...THIS BOUNDARY SHOULD LIFT SLOWLY NWD BEING
POSITIONED ACROSS SCNTRL IA EXTENDING EWD INTO NCNTRL IL. ALONG AND
S OF THIS BOUNDARY...SFC HEATING WILL LIKELY RESULT IN MODERATE
INSTABILITY WITH 2000 TO 3000 MLCAPE BY MID-AFTERNOON. HOW FAR NWD
THIS BOUNDARY CAN GET REMAINS IN QUESTION BUT THE INSTABILITY
COMBINED WITH THE UPPER-TROUGH APPROACHING FROM THE NRN PLAINS
EVIDENT ON WV IMAGERY SHOULD PROVIDE SUFFICIENT LIFT FOR
THUNDERSTORM DEVELOPMENT ALONG THE BOUNDARY THIS AFTERNOON ACROSS
SCNTRL IA. A BAND OF STRONGER MID-LEVEL FLOW ROUNDING THE BASE OF
THE TROUGH WILL INCREASE DEEP LAYER SHEAR DURING THE AFTERNOON
ACROSS IA/NRN MO. FORECAST SOUNDINGS SHOW 0-6 SM SHEAR OF 4O TO 50
KT SUGGESTING SUPERCELLS AND/OR BOW ECHOES WILL BE LIKELY AS A
BROKEN LINE OF CONVECTION DEVELOPS AND SPREADS EWD ACROSS
ECNTRL-SERN IA/NERN MO AND INTO WCNTR-NW IL THIS EVENING.
SUPERCELLS SHOULD BE CAPABLE OF PRODUCING A FEW TORNADOES ALONG THE
WARM FRONT SE OF THE SFC LOW ACROSS ERN IA WHERE THE LOW-LEVEL JET
WILL BE STRONGEST. AN ISOLATED TORNADO WILL ALSO BE POSSIBLE
FARTHER SW ALONG A COLD FRONT MOVING ACROSS ERN KS/NRN MO LATE THIS
AFTERNOON/EVENING. BOW ECHOES IN THE LINE WILL HAVE A WIND DAMAGE
POTENTIAL WITH GUSTS OVER 70 MPH POSSIBLE WITH A FEW STORMS.
EMBEDDED SUPERCELLS WITHIN THE LINE WILL ALSO HAVE A WIND
DAMAGE/LARGE HAIL THREAT. 

...MD/VA/DE/SERN PA/NJ... 
SFC DEWPOINTS IN THE UPPER 60S TO LOWER 70S F EXIST CURRENTLY
ACROSS VA/ERN MD/NJ. STRONG SFC HEATING ALONG THE MOISTURE AXIS
WILL LIKELY RESULT IN MODERATE INSTABILITY WITH MLCAPE OF 2000 TO
3000 J/KG ALONG THE MID-ATLANTIC COASTAL AREAS BY AFTERNOON. A
STATIONARY FRONTAL BOUNDARY EXTENDS E TO W FROM OH TO MD. THIS WILL
BE A FOCUS FOR CONVECTION THIS AFTERNOON. ALTHOUGH...MID-LEVEL WIND
FIELDS WILL DECREASE SOME DURING THE DAY...FORECAST SOUNDINGS SHOW
35 KT AT 500 MB BY 21Z. THIS COUPLED WITH THE VERY UNSTABLE AIR MAY
BE ENOUGH FOR AN ISOLATED SEVERE STORM MAINLY ACROSS NRN VA/MD OR
SERN PA BY MID AFTERNOON. AN ISOLATED DAMAGING WET MICROBURST WOULD
BE THE MAIN THREAT CONSIDERING THE MODERATE SHEAR AND ABUNDANT LOW-
LEVEL MOISTURE. 

..BROYLES/TAYLOR.. 07/09/03

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