Severe Storm Outlook Narrative (AC)
Issued by NWS

Home | Current Version | Previous Version | Text Only | Print | Product List | Glossary On
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
000
ACUS01 KWNS 021242
SWODY1
SPC AC 021241

DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0741 AM CDT TUE SEP 02 2014

VALID 021300Z - 031200Z

...THERE IS A SLGT RISK OF SVR TSTMS TODAY FROM ERN KY NEWD TO
CENTRAL NY...

...SUMMARY...
A FEW DAMAGING GUSTS WILL BE POSSIBLE FROM THE EASTERN KENTUCKY AREA
NORTHEASTWARD TO CENTRAL NEW YORK...MAINLY THIS AFTERNOON.  OTHER
ISOLATED STRONG TO SEVERE STORMS WILL BE POSSIBLE FROM THE MID SOUTH
TO OKLAHOMA TODAY...AND INTO KANSAS OVERNIGHT.

...SYNOPSIS...
WITHIN A LARGELY ZONAL FLOW REGIME...A SHORTWAVE TROUGH OVER ERN IA
THIS MORNING WILL PROGRESS EWD TO THE LOWER GREAT LAKES THIS EVENING
AND NRN NEW ENGLAND OVERNIGHT.  UPSTREAM...ANOTHER SHORTWAVE TROUGH
WILL MOVE ESEWD FROM VANCOUVER ISLAND TO THE NRN ROCKIES.  AT THE
SURFACE...A WEAK COLD FRONT WILL MOVE INTO WRN NY/PA THIS AFTERNOON
AND EVENING.  THE BOUNDARY WILL BECOME MORE DIFFUSE WITH SWWD
EXTENT...ASIDE FROM WHERE IT IS BEING REINFORCED BY ONGOING
CONVECTION IN OK.  THIS WRN PORTION OF THE EFFECTIVE BOUNDARY WILL
MOVE SEWD WITH CONVECTIVE OUTFLOW TODAY...BUT THEN STALL AND THEN
MOVE NWD AS A WARM FRONT OVERNIGHT INTO KS.

...OH VALLEY TO NY TODAY...
ONGOING CONVECTION ACROSS THE LOWER OH VALLEY MAY PERSIST INTO THE
DAY WHILE DEVELOPING ESEWD TOWARD ERN KY/WV.  IN THE WAKE OF THIS
CONVECTION...SOME REDUCTION IN LOW-LEVEL MOISTURE AND RESIDUAL CLOUD
COVER CAST DOUBT ON THE DEGREE OF DESTABILIZATION AND RENEWED
THUNDERSTORM DEVELOPMENT ALONG THE WEAK SYNOPTIC FRONT.  THE SAME
PRE-FRONTAL BAND OF CONVECTION BECOMES MORE DIFFUSE INTO OH...BUT
COULD STILL ACT AS THE PRIMARY FOCUS FOR THUNDERSTORM DEVELOPMENT
DURING THE DAY INTO WRN PA/NY.  THOUGH LAPSE RATES WILL BE
POOR...68-70 F BOUNDARY LAYER DEWPOINTS AND SOME DAYTIME HEATING
WILL SUPPORT MLCAPE OF 500-1500 J/KG.  THIS BUOYANCY WILL COINCIDE
WITH AN ENHANCED BELT OF MIDLEVEL FLOW ACCOMPANYING THE SHORTWAVE
TROUGH /40-50 KT IN THE 700-500 MB LAYER/...THUS A FEW DAMAGING
GUSTS WILL BE POSSIBLE WITH CLUSTERS/LINE SEGMENTS PRIOR TO
CONVECTION WEAKENING BY LATE EVENING.

...OK TO MID SOUTH TODAY...AND KS TONIGHT...
CONVECTION IS ONGOING IN OK...THE CONVECTION SHOULD WEAKEN LATER
THIS MORNING AS THE SWLY LLJ WEAKENS AND MOISTURE INFLUX INTO THE
CONVECTION IS REDUCED.  FARTHER E...STORMS COULD REGENERATE ALONG
THE OUTFLOW AS IT SPREADS SEWD TOWARD ERN AR/NW MS WHERE THE RICHER
MOISTURE AND WEAKER CAP RESIDE COMPARED TO AREAS FARTHER W.  THE
STORMS WILL ALSO BE MOVING INTO AN AREA WITH WEAKER VERTICAL
SHEAR...WHICH SUGGESTS THAT ISOLATED DOWNBURSTS WILL BE THE MAIN
THREAT AFTER THIS MORNING.

OUTFLOW WITH THE OK STORMS WILL SAG S OF THE STRONGER FLOW
ALOFT/VERTICAL SHEAR...AND IT IS NOT CLEAR IF NEW SURFACE-BASED
STORMS WILL FORM THIS AFTERNOON ALONG THE OUTFLOW BOUNDARY IN
CENTRAL OK GIVEN A STRONG CAP NOTED IN THE 12Z OUN SOUNDING.  THE
MORE PROBABLE SCENARIO IS FOR ELEVATED STORMS TO FORM TONIGHT IN KS
AS THE SURFACE BOUNDARY LIKELY ASSUMES WARM FRONTAL CHARACTERISTICS
AND THE NOCTURNAL SLY LLJ STRENGTHENS.  ISOLATED LARGE HAIL WILL BE
THE MAIN THREAT WITH ANY OVERNIGHT CONVECTION IN KS.

..THOMPSON/MOSIER.. 09/02/2014




USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.