Quantitative Precipitation Forecast
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FOUS30 KWBC 161456
QPFERD

EXCESSIVE RAINFALL DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1055 AM EDT FRI JUN 16 2017

...VALID 15Z FRI JUN 16 2017 - 12Z SAT JUN 17 2017...
...REFERENCE AWIPS GRAPHIC UNDER...DAY 1 EXCESSIVE RAINFALL...


MARGINAL RISK OF RAINFALL EXCEEDING FFG TO THE RIGHT OF A LINE FROM
10 SW IJX 10 SW TBN 20 N GMJ WLD 10 SSW EWK 25 W TOP SDA
10 SSE AXA 25 N DEH 15 ENE DLL ENW IGQ 10 SW IJX.

MARGINAL RISK OF RAINFALL EXCEEDING FFG TO THE RIGHT OF A LINE FROM
30 SW 2W6 NGU 10 SSE ECG 15 ESE OCW 15 S LHZ 25 WNW 45J
15 NNE EHO TRI 35 WNW I16 30 ENE PKB 10 SW JST 15 W THV BWI
30 SW 2W6.

SLIGHT RISK OF RAINFALL EXCEEDING FFG TO THE RIGHT OF A LINE FROM
20 N CHO 15 S HSP 20 WSW PSK 15 SE I16 35 ESE 48I 25 WNW W99
20 WSW OKV 20 N CHO.


1200 UTC UPDATE...

UPDATED THE DAY 1 ERO TO BROADEN THE MARGINAL RISK AREA A BIT
FARTHER TO THE WEST ACROSS WV...WHILE ALSO INCORPORATING A NARROW
SLIGHT RISK AREA ALONG THE VA-WV BORDER CORRESPONDING TO THE LOWER
FFG/HIGHER ANTECEDENT SOIL MOISTURE. WITHIN THE SLIGHT RISK
AREA...THE LATEST (06Z-BASED) SSEO 40KM NEIGHBORHOOD GUIDANCE
INDICATES 3 HOURLY QPF>FFG EXCEEDANCE PROBABILITIES OVER 50%
DURING THE AFTERNOON WHEN MIXED LAYER CAPES ARE EXPECTED TO
AVERAGE BETWEEN 1000-1500 J/KG...WHILE THE AREA REMAINS ON THE
WESTERN PERIPHERY OF THE MOISTURE PLUME/WARM CONVEYOR BELT FOR
MUCH OF THE DAY AHEAD OF THE SLOWLY ADVANCING UPPER SHORTWAVE.

HURLEY


PREVIOUS DISCUSSION BELOW...


...MID ATLC REGION...

ACRS THE EAST COAST...STABLE HIGH PRES WILL CONTINUE TO SHIFT OFF
THE EAST COAST ALLOWING DEEPER MSTR AND INCREASING INSTABILITIES
TO DVLP ACRS THE REGION ON FRI/FRI NIGHT.  POTNLY HEAVY
SHWRS/TSTMS ARE LIKELY ACRS PORTIONS OF THE MID ATLC REGION FRI
AFTN AND NIGHT AS WEAK NEARLY UNIDIRECTIONAL FLOW DVLPS IN ADVANCE
OF UPSTREAM BROAD UPPER TROF..POSSIBLY SUPPORTING SOME SLOW MOVING
BANDS OF CONVECTION THAT COULD LEAD TO ISOLD HEAVIER RAIN TOTALS
THERE. THERE IS MULTI HI RES MODEL SUPPORT FOR ISOLD RAINFALL
TOTALS IN EXCESS OF 3 INCHES IN A COUPLE HOURS PARTICULARLY ACRS
PORTIONS OF CNTL VA NWD INTO CNTL MD.  TIME LAGGED ENSEMBLE RUNS
OF THE HRRR SHOW PROBABILITIES OF 3 INCH OR GREATER RAINFALL
AMOUNTS IN 3 HOURS EXCEEDING 50 PCT WHICH WOULD SUPPORT AT LEAST A
MARGINAL RISK OF EXCESSIVE RAINS AT THIS TIME.

...MID MISSISSIPPI VALLEY...
MODELS SUGGEST AN INCREASING THREAT OF CONVECTION FRI AFTN/NIGHT
INITIALLY ALONG AND NORTH OF OF STATIONARY FRONT AND WEAK SFC LOW
DVLPG AHEAD OF JET STREAK PUSHING ACRS THE NORTHERN PLAINS.  WITH
MODELS SHOWING STGLY DIFFLUENT THICKNESSES..HIGH INSTABILITY..AND
MODEST SWLY WAA DIRECTED INTO THE STALLED FRONT...INGREDIENTS
APPEAR FAVORABLE FOR RAPID CELL GROWTH WITH POTNL FOR MULTIPLE
CELL CLUSTERS OR PERHAPS MCS DVLPMENT.  MODELS HOWEVER SHOW QUITE
A BIT OF VARIABILITY WITH QPF AMOUNTS AND PLACEMENT ACRS THIS
REGION LEADING TO RATHER LOW CONFIDENCE IN QPF DETAILS.   AT THIS
TIME IT WOULD APPEAR THE GREATER THREAT OF HEAVIER RAINS WOULD
TEND TO FOCUS FROM PARTS OF IOWA SWD INTO NRN MO AND PERHAPS ERN
KS WITH LATEST HIGH RES GUIDANCE INDICATING THE POTNL FOR ISOLD
RAINFALL AMOUNTS IN EXCESS OF 3 INCHES.  GIVEN THE
UNCERTAINTY..HAVE ONLY INDICATED A MARGINAL RISK FOR EXCESSIVE
RAINS...BUT WILL CONTINUE TO MONITOR WITH PERHAPS THE 12Z GUIDANCE
PROVIDING BETTER CLARITY.

SULLIVAN


$$





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