Quantitative Precipitation Forecast
Issued by NWS

Current Version | Previous Version | Graphics & Text | 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
857
FOUS30 KWBC 030757
QPFERD

EXCESSIVE RAINFALL DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
257 AM EST WED FEB 03 2016

...VALID 12Z WED FEB 03 2016 - 12Z THU FEB 04 2016...
...REFERENCE AWIPS GRAPHIC UNDER...DAY 1 EXCESSIVE RAINFALL...


SLIGHT RISK OF RAINFALL EXCEEDING FFG TO THE RIGHT OF A LINE FROM
DOV 15 W 2W6 HNZ UDG 30 N NBC 20 ESE AYS 15 WNW CTY 70 SSE AAF
95 SW AAF 35 S JKA 15 SSW GZH ALX 10 NE DNN 10 SW TYS 25 WNW TRI
35 W I16 20 N 48I 15 SW LBE 20 NE DUJ 15 ESE DSV ART 20 NNW SLK
10 E MPV 45 NE BML 15 WSW BGR 20 ENE RKD 15 S PSM 15 N WST
30 E BLM DOV.

MODERATE RISK OF RAINFALL EXCEEDING FFG TO THE RIGHT OF A LINE FROM
25 SW AYS 15 SW 40J 25 SE AAF 25 S PAM PFN 15 S 11J 15 NE ABY
15 WNW DQH 25 SW AYS.


...EASTERN SEABOARD...

ALONG THE EASTERN SEABOARD STRETCHING FROM THE EASTERN GULF COAST
STATES NORTH THROUGH THE MID-ATLANTIC AND NEW ENGLAND...THERE WILL
BE A PATTERN OF MUCH ABOVE AVERAGE PW VALUES ALONG AND AHEAD OF A
SLOW-MOVING COLD FRONT...WHICH ARE FORECAST TO BE 3 TO 4 STANDARD
DEVIATIONS ABOVE THE MEAN OVER BASICALLY THE ENTIRE EASTERN
SEABOARD TO THE EAST OF THE APPALACHIANS. THIS AXIS OF ANOMALOUS
MOISTURE WILL BE COURTESY OF AN IMPRESSIVELY STRONG SOUTHERLY LOW
LEVEL JET WHICH A CONSENSUS OF MODELS INDICATES REACHING AS HIGH
AS 50 TO 70 KTS AHEAD OF THE FRONT AND THUS RESULTING IN EXTREMELY
HIGH MOISTURE FLUX ANOMALIES OF AS MUCH AS 4 TO 5 STANDARD
DEVIATIONS ABOVE NORMAL IN THE 850/700 MB LAYER. WIDESPREAD
MODERATE TO HEAVY RAIN IS EXPECTED WITHIN THIS AXIS OF HIGHER PWS
WHERE CONVERGENT LOW LEVEL FLOW WILL BE COINCIDING WITH A
RELATIVELY DIVERGENT FLOW REGIME ALOFT IN THE 500/300 MB LAYER.
THE GLOBAL MODELS HAVE BEEN CONSISTENTLY UNDERDONE WITH THEIR QPF
FOR THIS EVENT...AND THE 00Z NAM AND 00Z GFS AGAIN APPEAR TO BE
SIMPLY NOT GENERATING ENOUGH HEAVY RAIN GIVEN SUCH ANOMALOUS
MOISTURE TRANSPORT. SOME AREAS ALONG THE EAST COAST MAY APPROACH
OR EXCEED RECORD PW VALUES FOR THE MONTH OF FEBRUARY ON WED...AND
WITH THE SYNOPTIC SET-UP...HEAVY RAINS ARE GUARANTEED OVER A LARGE
AREA OF THE EASTERN SEABOARD. THE NON-NCEP GUIDANCE IS A BIT
WETTER AND ESPECIALLY THE 00Z UKMET...BUT EVEN THESE MODELS HAVE
TENDED TO BE LOCALLY UNDERDONE.

WIDESPREAD 1 TO 2 INCH RAINS ARE ANTICIPATED ACROSS AREAS
INCLUDING THE MID-ATLANTIC AND NORTHEAST...AND ESPECIALLY IN
VICINITY OF HIGH TERRAIN WHERE OROGRAPHIC FORCING WILL BE
ENHANCING RAINFALL RATES. THE HEAVIEST RAINS FOR THE PERIOD THOUGH
ARE EXPECTED TO BE DOWN ACROSS PORTION OF THE SOUTHEAST COASTAL
PLAIN AND INTO THE FL PANHANDLE. PERSISTENTLY CONVERGENT LOW LEVEL
FLOW JUST AHEAD OF THE SLOW-MOVING COLD FRONT COUPLED WITH A MUCH
BETTER DEFINED AXIS OF INSTABILITY WILL PROMOTE ORGANIZED AND
LOCALLY VERY HEAVY CONVECTIVE RAINS HERE WHICH IS STRONGLY
ADVERTISED BY THE 00Z WRF-ARW AND THE 00Z NSSL-WRF SOLUTIONS.
RAINFALL AMOUNTS HERE OF 3 TO 5 INCHES WITH LOCALLY HEAVIER
AMOUNTS ARE POSSIBLE. GIVEN THE HEAVY RAINFALL AMOUNTS OVER
PORTIONS OF THE MID-ATLANTIC AND NORTHEAST WHERE THERE HAS BEEN
ONGOING SNOW-MELT...EXPECT THERE TO BE CONCERNS FOR RUNOFF
PROBLEMS AND FLOODING. ADDITIONAL CONCERNS FOR FLOODING ARE
EXPECTED DOWN ACROSS THE FL PANHANDLE AND INTO SOUTHWEST GA WITH
THE AFOREMENTIONED CONVECTIVE ORGANIZATION THAT IS EXPECTED TO BE
IN PLACE. WILL CONTINUE TO MONITOR.

ORRISON

$$





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