Quantitative Precipitation Forecast
Issued by NWS

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FOUS30 KWBC 221855
QPFERD

EXCESSIVE RAINFALL DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
154 PM EST THU JAN 22 2015

...VALID 18Z THU JAN 22 2015 - 00Z SAT JAN 24 2015...
...REFERENCE AWIPS GRAPHIC UNDER...DAY 1 EXCESSIVE RAINFALL...


 ...GULF COAST INTO THE SOUTHEAST...

WIDESPREAD HEAVY RAIN WILL EXPAND THROUGH THE CENTRAL AND EASTERN
GULF COAST AND SOUTHEAST THROUGH THE DAY 1 PERIOD...WITH A FAIRLY
LARGE SWATH OF 1 TO 2 PLUS INCHES OF RAIN EXPECTED...AS THE
AMPLIFIED SOUTHERN STREAM UPPER TROUGH PUSHES INTO THE ARKLATEX BY
00Z SAT WHILE A SURFACE LOW FORMS OVER THE GULF AND LIFTS
NORTHEAST INTO THE FL PANHANDLE. INCREASING UPPER LEVEL DIFFLUENCE
AND STRENGTHENING DEEP-LAYER SOUTHWESTERLY FLOW...ALONG WITH THE
RIGHT ENTRANCE REGION FORCING FROM THE JET STREAK TO THE
NORTH...WILL ALLOW FOR A STEEP N-S SLOPE OF THETA SURFACES AND AS
A RESULT SUPPORT STRONG ISENTROPIC ASCENT OVER THE AREA.
MOREOVER...40-50+ KT 850 MB SOUTHERLY INFLOW FROM THE GULF OF
MEXICO WILL LEAD TO MOISTURE FLUX ANOMALIES BETWEEN 3-4 STANDARD
DEVIATIONS ABOVE NORMAL ALONG THE GULF COAST AND INTO SOUTHERN
AL/GA...WHERE PRECIPITABLE WATER VALUES ARE EXPECTED TO PEAK
BETWEEN 1.5-1.75 INCHES. DEEP LAYER INSTABILITY WILL CONTINUE TO
BE LACKING...ESPECIALLY FARTHER AWAY FROM THE GULF COAST...AS
MODEL MUCAPES TOP OUT BETWEEN 200-600 J/KG FROM ALONG THE GULF
COAST INTO SOUTHERN AL/GA.

FOR MOST OF THIS REGION...THE EXISTING HIGH FFG VALUES (3-4" IN 3
HRS AND 4-5" IN 6 HRS) WOULD PRECLUDE ANY ORGANIZED EXCESSIVE
RAINFALL THREAT...THOUGH CAN NOT RULE OUT THE POTENTIAL FOR
ISOLATED SHORT-TERM RUNOFF ISSUES. ESPECIALLY OVER SOUTHERN
LA/MS/AL/GA AND INTO THE FL PANHANDLE...GIVEN THE INCREASING
(THOUGH STILL MARGINAL) CONVECTIVE POTENTIAL TONIGHT AND FRI...AND
WITH THE POTENTIAL FOR TRAINING OF CONVECTION AS THE STRONG LOW
LEVEL INFLOW BECOMES MORE ALIGNED WITH THE MEAN 850-300 MB FOR A
BRIEF PERIOD (AROUND 3-6 HOURS) AS THE UPPER TROUGH AXIS
APPROACHES.

HURLEY
$$





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