Quantitative Precipitation Forecast
Issued by NWS

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FOUS30 KWBC 290837
QPFERD

EXCESSIVE RAINFALL DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
434 AM EDT MON MAY 29 2017

...VALID 12Z MON MAY 29 2017 - 12Z TUE MAY 30 2017...
...REFERENCE AWIPS GRAPHIC UNDER...DAY 1 EXCESSIVE RAINFALL...


MARGINAL RISK OF RAINFALL EXCEEDING FFG TO THE RIGHT OF A LINE FROM
85 SE KOPM 55 SE BRO 40 S MMMA 50 S MMRX 60 SW MMRX 40 ENE MMMY
25 SSE MMNL 60 NNW RBO CXO 40 NE IER 45 SE GWO 30 NNE DNN
15 SSE GYH 25 S HQU 25 NNW 11J 30 WNW NSE 20 NNE SRN 10 SW W60.


...WESTERN GULF COAST NORTHEAST THROUGH THE LOWER MISSISSIPPI
VALLEY AND INTO THE SOUTHEAST...

THE SLOW-MOVING MID/UPPER LEVEL LOW ACROSS THE UPPER MIDWEST WILL
MAINTAIN THE CONFLUENT UPPER FLOW AND RESULTANT JET AXIS ACROSS
THE MID MS VALLEY INTO THE NORTHERN MID ATLANTIC-NORTHEAST REGION
DURING THE DAY 1 PERIOD. THIS SETUP WILL CONTINUE TO REINFORCE THE
QUASI-STATIONARY SURFACE BOUNDARY DRAPED FROM SOUTH TX ENE THROUGH
THE LOWER MS VALLEY...TN VALLEY...AND LOWER MID ATLANTIC REGION.
RAINFALL COVERAGE/INTENSITY ALONG AND SOUTH OF THIS BOUNDARY WILL
REMAIN THE PRIMARY FORECAST CHALLENGE...ESPECIALLY GIVEN THE
CONVECTIVE COMPONENT AS MID/UPPER LEVEL PERTURBATIONS (MCV/S)
CONTINUE TO CAUSE WAVES ALONG THE FRONT ALONG WITH A
RE-DISTRIBUTION OF DEEP LAYER FORCING.

THE NON-NAM MODELS ARE IN FAIRLY GOOD AGREEMENT WITH THE MORE
PRONOUNCED MCV ACROSS SOUTH TX EARLY MON LIFTING ENE ALONG THE
WESTERN-CENTRAL GULF COAST LATER MON-MON NIGHT. THE NAM MEANWHILE
IS AN OUTLIER SOLUTION IN THAT IT DEPICTS A MORE ELONGATED VORT
LOBE STRETCHING NORTHWARD IN THE LOWER MS/LOWER TN VALLEY. THE
TRACK OF THIS MCV... ALONG WITH ENHANCED DEEP-LAYER
ASCENT/LOW-LEVEL FGEN WITHIN THE RIGHT ENTRANCE REGION OF PERIODIC
UPPER JET STREAKS TRAVERSING THE MID MS VALLEY-OH VALLEY...WILL
MAINTAIN A NON-UNIFORMITY OF FAVORABLE FORCING AND THUS A SOMEWHAT
DISJOINTED PCPN PATTERN ALONG AND SOUTH OF THE SURFACE FRONT. WPC
CONTINUED TO LEAN MORE HEAVILY ON THE HIGH-RES CAMS...WRF-ARW AND
PARALLEL ARW IN PARTICULAR...WITH THE TIMING AND PLACEMENT OF
AMOUNTS.

DESPITE THE FAVORABLE THERMODYNAMIC PATTERN AHEAD OF THE FRONT
(PWS 1.75-2.0+ INCHES...MIXED-LAYER CAPES AOA 1500-2000
J/KG)...ALONG WITH THE DYNAMICAL FORCING AHEAD OF THE MCV AND/OR
WITHIN THE REGION OF FAVORABLE UPPER JET FORCING...THE RELATIVELY
WEAK LOW-LEVEL INFLOW AND NEGLIGIBLE MOISTURE FLUX ANOMALIES WILL
LIMIT THE PERSISTENCE OF HEAVY RAIN AREAS. MOREOVER...THE AIRMASS
BEHIND THE DEPARTING MCV WILL LIKELY REQUIRE SEVERAL HOURS TO
RE-DESTABILIZE. AS A RESULT...WPC WILL MAINTAIN ONLY A MARGINAL
RISK FOR EXCESSIVE RAINFALL...WITH THE ANTICIPATION THAT ANY
SHORT-TERM RUNOFF ISSUES WOULD BE ISOLATED AT MOST CONSIDERING THE
CURRENT SOIL MOISTURE/FFG VALUES.

HURLEY
$$





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