Quantitative Precipitation Forecast
Issued by NWS

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FOUS30 KWBC 160832
QPFERD

EXCESSIVE RAINFALL DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
427 AM EDT MON OCT 16 2017

...VALID 12Z MON OCT 16 2017 - 12Z TUE OCT 17 2017...
...REFERENCE AWIPS GRAPHIC UNDER...DAY 1 EXCESSIVE RAINFALL...


MARGINAL RISK OF RAINFALL EXCEEDING FFG TO THE RIGHT OF A LINE FROM
25 ENE SGJ 25 SSE SGJ 40 SSW SGJ 20 NNE GNV 30 NNW JAX SAV
10 N NBC 30 SSW CHS 35 ESE HXD.


...SOUTHEAST COAST...

AN UPPER LEVEL TROUGH ACROSS THE OH/TN VALLEYS EARLY THIS MORNING
WILL TRANSLATE EASTWARD TO ALONG THE MID ATLANTIC-SOUTHEAST COAST
BY 12Z TUE. STRONG...ELONGATED DEEP-LAYER WESTERLY FLOW IN ITS
WAKE WILL FOSTER SUCH SWIFT EASTWARD PROGRESSION OF THE UPPER
TROUGH AND ASSOCIATED SURFACE COLD FRONT...PARTICULARLY FARTHER
NORTH (MID ATLANTIC)... THOUGH WITH THE WEAKER WESTERLIES THE
UPPER TROUGH WILL RETARD SOMEWHAT OVER THE EASTERN GULF COAST
WHILE THE SURFACE BOUNDARY BECOMES NEARLY STATIONARY ACROSS SOUTH
FLORIDA BY 12Z TUE. NEVERTHELESS...MODEST AT BEST UPPER LEVEL
FORCING AND WEAKENING 850-700 MB MOISTURE TRANSPORT/FLUX WITH
TIME...ALONG WITH THE LIMITED DEEP-LAYER INSTABILITY
OVERNIGHT...WILL INHIBIT THE HEAVY RAINFALL THREAT (CONVECTIVE
TRAINING POTENTIAL) ACROSS MUCH OF THE FL PENINSULA DESPITE THE
SLOWER SURFACE FRONTAL PROGRESSION.

HOWEVER...AN INCREASED CHANCE FOR CELL TRAINING AND THUS HEAVY
RAINFALL WILL BE POSSIBLE THROUGH THIS EVENING ALONG THE SOUTHEAST
COAST...CAPITALIZING ON THE LINGERING DIURNAL INSTABILITY (MUCAPES
1000-1500 J/KG). UTILIZING A MULTI-MODEL BLEND WITH THE QPF...WITH
THE BULK OF THE WEIGHT COMPRISING THE HIGH-RES CAMS (ESPECIALLY
THE NBM AND HREF MEAN)...MAXIMUM AREAL-AVERAGE RAINFALL AMOUNTS
ARE EXPECTED TO RANGE BETWEEN 0.75-1.50" ALONG THE SOUTHEAST COAST
FROM NORTHEAST FL TO SOUTHERN SC. SPOTTY 2-3+" TOTALS ARE LIKELY
HOWEVER PER THE VARIOUS HIGH-RES WRFs. GIVEN THAT THESE AMOUNTS
COULD FALL WITHIN A 3 HOUR PERIOD...ALONG WITH THE CURRENT SOIL
MOISTURE ANALYSIS FROM THE NATIONAL WATER MODEL...THE CURRENT 1-3
HOURLY FFG...AND THE LATEST SSEO 40KM NEIGHBORHOOD PROBABILITIES
OF QPF>FFG EXCEEDANCE LATER THIS AFTERNOON (TOWARD 00Z)...WE WILL
INCLUDE A NARROW "MARGINAL" RISK AREA IN THE DAY 1 EXCESSIVE
RAINFALL OUTLOOK (ERO).

HURLEY
$$





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