SWODY1
SPC AC 011959
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0259 PM CDT SUN APR 01 2012
VALID 012000Z - 021200Z
...THERE IS A SLGT RISK OF SVR TSTMS ACROSS PARTS OF THE OH VALLEY
AND CNTRL APPALACHIAN MTNS...
THE MAIN CHANGE TO THE OUTLOOK IS TO NARROW THE HIGHER END
PROBABILITIES TO A CORRIDOR FROM SE IND SEWD ACROSS NRN KY. MODERATE
INSTABILITY SHOULD DEVELOP ACROSS THE AREA AS MOISTURE CONTINUES TO
ADVECT EWD THIS AFTERNOON. SHORT-TERM MODEL FORECASTS ARE IN GENERAL
AGREEMENT THAT THE GREATEST CONVECTIVE THREAT EARLY THIS EVENING
WILL EXIST SEWD ACROSS THE CINCINNATI AREA WHERE THE COMBINATION OF
DEEP LAYER SHEAR AND INSTABILITY MAY SUPPORT A THREAT FOR SUPERCELLS
WITH VERY LARGE HAIL. OTHERWISE...THE OUTLOOK LOOKS TO BE ON TRACK.
..BROYLES.. 04/01/2012
.PREV DISCUSSION... /ISSUED 1118 AM CDT SUN APR 01 2012/
...SYNOPSIS...
LARGE-SCALE PATTERN WILL UNDERGO FURTHER AMPLIFICATION DURING THE D1
PERIOD AS WRN U.S. TROUGH PROGRESSES INTO THE ROCKIES...AND A
DOWNSTREAM RIDGE BUILDS FROM THE CANADIAN PRAIRIE PROVINCES THROUGH
THE MS RIVER VALLEY. E OF THE RIDGE...AN 80-90 KT MIDLEVEL JET
STREAK OVER SRN ONTARIO WILL DIG SEWD TOWARD THE MID-ATLANTIC
COAST...SUPPORTING INTENSIFICATION OF A TROUGH FROM THE CANADIAN
MARITIMES INTO NWRN ATLANTIC.
IN THE LOW LEVELS...A COLD FRONT ADVANCING SWD FROM THE GREAT LAKES
WILL MERGE WITH A WARM FRONT LIFTING NWD/NEWD THROUGH THE OH
VALLEY...ENHANCING BAROCLINITY OVER THESE AREAS. ELSEWHERE...A COLD
FRONT WILL MOVE FROM THE NRN ROCKIES EWD/SEWD THROUGH NRN
PLAINS...WHERE IT WILL INTERSECT A DRYLINE OR PRE-FRONTAL TROUGH
EXTENDING FROM CNTRL PARTS OF NEB/KS INTO SWRN TX.
...OH VALLEY INTO CNTRL APPALACHIANS THIS AFTERNOON/TONIGHT...
MASS RESPONSE TO ABOVE-MENTIONED JET STREAK --MANIFEST AS A WLY 30
KT LLJ-- WILL ENHANCE THE EWD FLUX OF A WARM AND MOIST BOUNDARY
LAYER CURRENTLY OBSERVED NEAR THE CONFLUENCE OF THE MS AND OH RIVERS
EWD ACROSS REGION TODAY. THIS PROCESS WILL OCCUR BENEATH THE ERN
EXTENSION OF AN EML /CHARACTERIZED BY MIDLEVEL LAPSE RATES OF
7.0-7.5 C PER KM/...YIELDING AFTERNOON MLCAPE VALUES OF 1000-2500
J/KG ACROSS EWD-DEVELOPING WARM SECTOR.
REGENERATIVE TSTM DEVELOPMENT IS ANTICIPATED THIS AFTERNOON OVER
PARTS OF IND/OH OWING TO PERSISTENT LOW-LEVEL WAA AND GLANCING
INFLUENCE OF IMPULSE DIGGING SEWD THROUGH THE LOWER GREAT LAKES.
STORMS MAY SUBSEQUENTLY BUILD WWD INTO A PROGRESSIVELY MORE
UNSTABLE...BUT STRONGER CAPPED ENVIRONMENT. FORECAST HODOGRAPHS
EXHIBIT PRONOUNCED VEERING OF WINDS WITH HEIGHT WITH 40-50 KT OF
EFFECTIVE BULK SHEAR. AS SUCH...THE POTENTIAL FOR SUPERCELLS WILL
EXIST WITH AN ATTENDANT RISK FOR VERY LARGE HAIL...DAMAGING WINDS
AND PERHAPS A COUPLE OF TORNADOES.
STORMS WILL LIKELY CONGEAL INTO A FORWARD-PROPAGATING MCS LATER THIS
EVENING INTO TONIGHT WITH A THREAT FOR DAMAGING WINDS AND LARGE HAIL
CONTINUING ACROSS PARTS OF THE CNTRL APPALACHIANS.
...UPPER MS VALLEY LATE TONIGHT...
40-50 KT LLJ OVER THE DAKOTAS WILL MIGRATE EWD INTO MN TONIGHT IN
ADVANCE OF NRN SEGMENT OF WRN CONUS TROUGH MOVING THROUGH THE NRN
ROCKIES. THIS WILL SUPPORT THE NWD FLUX OF A HIGHER THETA-E AIR
MASS INTO THE AREA BENEATH NRN EXTENSION OF EML...YIELDING MUCAPE OF
AROUND 1500 J/KG. LATEST MODEL GUIDANCE CONTINUES TO SUGGEST THAT
AT LEAST ISOLATED STORMS WILL BE POSSIBLE LATE TONIGHT INTO MONDAY
MORNING...SOME OF WHICH MAY CONTAIN SEVERE HAIL.
...S TX LATE THIS AFTERNOON/EVENING...
A LOW-PROBABILITY RISK FOR HAIL AND/OR LOCALLY DAMAGING WIND GUST
WILL EXIST LATE THIS AFTERNOON INTO EVENING IN ASSOCIATION WITH ANY
STORMS DEVELOPING NEAR MIDLEVEL CIRCULATION ALONG THE TX COAST OR
MOVING OFF THE HIGHER TERRAIN OF NRN MEXICO.
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