SWODY1
SPC AC 192003
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0303 PM CDT MON JUL 19 2010
VALID 192000Z - 201200Z
...THERE IS A SLGT RISK OF SVR TSTMS FROM THE CNTRL PLNS INTO THE OH
VLY...
...THERE IS A SLGT RISK OF SVR TSTMS FROM THE NRN HI PLNS SE INTO
THE CNTRL PLNS...
...MID MS INTO OH VLYS...
CNTRL IL MCS HAS BECOME BETTER DEFINED IN THE PAST HOUR. EARLIER
TODAY...SYSTEM MAY HAVE BEEN ENHANCED/SUPPORTED BY A LOW AMPLITUDE
UPR IMPULSE NOW ENTERING NRN IL. IN RECENT HOURS THIS FEATURE
APPEARS TO HAVE LOST DEFINITION. BUT THERMODYNAMIC ENVIRONMENT
DOWNSTREAM ACROSS IND/SRN AND CNTRL OH...W/E AXIS OF LWR
TROPOSPHERIC CONFLUENCE ALONG ROUGHLY THE I-70 CORRIDOR...AND DEEP
WIND PROFILES SUGGEST THAT MCS SHOULD FORWARD-PROPAGATE ESE THROUGH
THIS EVE. ADDITIONAL FORWARD-PROPAGATING/BOW SEGMENTS COULD ALSO
EVOLVE A BIT LATER THIS AFTN/EVE OVER SRN IL. THE STORMS COULD
AFFECT PARTS OF OH...KY...AND PERHAPS WV WITH DMGG WINDS BEFORE THEY
WEAKEN LATER TONIGHT.
FARTHER UPSTREAM...A SEPARATE AREA OF NEW STORMS COULD DEVELOP LATER
THIS AFTN AND EVE IN ZONE OF STRENGTHENING WAA/ASCENT ATOP POST-MCS
STORM OUTFLOW OVER NRN MO/WRN IA AND PERHAPS NE KS /REF MCD 1364/.
...NE CO/SE WY/SW NEB...AND NW KS...
MESOSCALE AREA OF LOW LVL UPSLOPE FLOW BENEATH PLUME OF ENHANCED MID
LVL MOISTURE MAY YET INITIATE SCTD STRONG STORMS IN NERN CO/NW KS.
THESE MAY EVOLVE INTO A SMALL CLUSTER...WITH A THREAT FOR LOCALLY
DMGG WIND AND/OR SVR HAIL THROUGH LATE TONIGHT.
...NRN HI PLNS SEWD INTO NEB...
SETUP STILL REMAINS FAVORABLE FOR THE DEVELOPMENT OF SVR STORMS
LATER THIS AFTN THROUGH EARLY TUE FROM SRN/ERN MT SE ACROSS WRN SD
INTO NRN NEB...AS REGION FURTHER DESTABILIZES AHEAD OF DIFFLUENT UPR
TROUGH MOVING ESE ACROSS CNTRL MT. SUPERCELLS APPEAR LIKELY...WITH
AN ATTENDANT RISK FOR LARGE HAIL...HIGH WINDS...AND ...ESPECIALLY
DURING THE EARLY STAGES OF STORM DEVELOPMENT...A TORNADO OR TWO.
..CORFIDI.. 07/19/2010
.PREV DISCUSSION... /ISSUED 1117 AM CDT MON JUL 19 2010/
...MID MS VALLEY...
A GENERALLY ZONAL FLOW PATTERN IS PRESENT TODAY OVER THE NORTHERN
THIRD OF THE UNITED STATES...WITH SEVERAL EMBEDDED SHORTWAVE TROUGHS
PROGRESSING EASTWARD. ONE FEATURE OVER MN/IA HAS RESULTED IN A
RATHER LONG-LIVED BAND OF THUNDERSTORMS MOVING ACROSS NORTHERN MO.
THESE STORMS APPEAR LIKELY TO PERSIST THROUGH THE DAY AND SPREAD
SOUTHEASTWARD INTO CENTRAL/SOUTHERN IL. AMPLE LOW LEVEL MOISTURE
AND MODERATE CAPE VALUES...COUPLED WITH 25-35 KNOTS OF WESTERLY MID
LEVEL FLOW...WILL SUPPORT A RISK OF MULTICELL STORMS CAPABLE OF
LOCALLY DAMAGING WINDS AND SOME HAIL. THESE STORMS MAY ALSO
BACKBUILD WESTWARD INTO PARTS OF SOUTHWEST MO LATER THIS AFTERNOON
WHERE MUCAPE VALUES OVER 4000 J/KG ARE EXPECTED.
...NEB/IA/MO...
OVERNIGHT CONVECTION HAS RESULTED IN A STRONG OUTFLOW BOUNDARY
SURGING SOUTHWARD INTO MO/KS. CLOUDS ALONG AND NORTH OF THIS
BOUNDARY WILL SUPPRESS DAYTIME HEATING AND DESTABILIZATION THROUGH
EARLY AFTERNOON. HOWEVER...CLOUDS ARE LIKELY TO DIMINISH LATER
TODAY WITH DEWPOINTS ACROSS THE REGION CLIMBING WELL INTO THE 70S.
THIS WILL LEAD TO A CORRIDOR OF VERY UNSTABLE AIR FROM SOUTHEAST NEB
ACROSS SOUTHERN IA/NORTHERN MO. A SHORTWAVE TROUGH MOVING ACROSS SD
WILL LIKELY PROVIDE THE FOCUS FOR THUNDERSTORM INTENSIFICATION.
FORECAST SOUNDINGS SUGGEST THE RISK OF DISCRETE SUPERCELLS DURING
THE FIRST FEW HOURS AFTER INITIATION OVER THIS AREA...WITH VERY
LARGE HAIL AND ISOLATED TORNADOES POSSIBLE. STORMS MAY CONGEAL INTO
A LARGE MCS AND TRACK EAST-SOUTHEASTWARD THIS EVENING.
...NY/PA INTO SOUTHERN NEW ENGLAND...
A SHORTWAVE TROUGH MOVING ACROSS NY/PA WILL HELP AFTERNOON
THUNDERSTORM DEVELOPMENT ALONG A CORRIDOR FROM EASTERN PA/NY INTO
MA/RI/CT. THIS AREA WAS AFFECTED BY EARLY MORNING STORMS...BUT IS
RECOVERING QUICKLY WITH DEWPOINTS NEAR 70F AND TEMPERATURES RISING
INTO THE MID 80S. MID LEVEL LAPSE RATES ARE WEAK...BUT THERE IS
SUFFICIENT FLOW ALOFT AND EFFECTIVE SHEAR FOR A FEW ORGANIZED
MULTICELL STORMS CAPABLE OF DAMAGING WINDS.
...MT/WY/SD...
WATER VAPOR IMAGERY SHOWS A SHORTWAVE TROUGH MOVING ACROSS ID/MT
THIS MORNING. THIS FEATURE WILL TRACK INTO EASTERN MT/WY BY THIS
EVENING...HELPING TO INITIATE SCATTERED THUNDERSTORMS OVER THE
HIGHER TERRAIN OF SOUTHERN MT/NORTHERN WY. THESE STORMS WILL
DEVELOP SOUTHEASTWARD DOWN THETA-E AXIS INTO WESTERN SD AND
EVENTUALLY INTO NORTHERN NEB. SUPERCELLS AND BOWS WILL BE POSSIBLE
ALONG THIS CORRIDOR WITH DAMAGING WINDS LIKELY THE MAIN THREAT.
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