Quantitative Precipitation Forecast
Issued by NWS

Current Version | Previous Version | Text Only | Print | Product List | Glossary Off
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

625
FOUS30 KWBC 290830
QPFERD

EXCESSIVE RAINFALL DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
430 AM EDT THU SEP 29 2016

...VALID 12Z THU SEP 29 2016 - 12Z FRI SEP 30 2016...
...REFERENCE AWIPS GRAPHIC UNDER...DAY 1 EXCESSIVE RAINFALL...


MARGINAL RISK OF RAINFALL EXCEEDING FFG TO THE RIGHT OF A LINE FROM
35 NNW CPW 30 W E33 15 W 4SL 20 NNW TCS 60 ENE DUG 40 SSE DUG
50 SSW DUG 25 ENE DMA 55 ENE FFZ 30 E PRC 10 W 40G 30 WNW PGA
45 N BCE 35 SE PVU 30 NNE PUC 30 WSW U28 30 S 4HV 50 WSW 4BL
40 SSW CNY 25 ENE CNY 45 ESE VEL 20 WNW CAG 15 ENE RIL 30 NW GUC
35 NNW CPW.

MARGINAL RISK OF RAINFALL EXCEEDING FFG TO THE RIGHT OF A LINE FROM
100 SE CHS 25 NE CHS 10 S UDG 10 NW HBI 30 W I16 30 W UNI
15 W MFD JYM 10 E LAN 30 N CYZR 30 SE BUF 30 NE IPT 10 SW SMQ
95 SSE FOK.

SLIGHT RISK OF RAINFALL EXCEEDING FFG TO THE RIGHT OF A LINE FROM
10 S EMV GSB 10 ENE TTA 25 ESE ROA 15 ENE CRW 15 NNW PHD
15 NE CXPT 30 ESE CTZR CWPS 20 NNW DUJ 10 NE UNV 15 NNW APG
15 SE WWD 25 SE WAL LFI 10 S EMV.

MODERATE RISK OF RAINFALL EXCEEDING FFG TO THE RIGHT OF A LINE FROM
15 ENE MGW 10 NW JST 20 E AOO 20 W THV 15 ENE GAI 15 SE NYG
25 SW OFP 25 NE LYH 30 NE HSP 15 NE EKN 15 ENE MGW.


...MID ATLANTIC INTO THE UPSLOPE AREA OF THE CENTRAL
APPALACHIANS...

THE 00Z GUIDANCE REMAINED IN OVERALL GOOD AGREEMENT WITH AN
ANOMALOUSLY DEEP UPPER LOW THAT IS FORECAST TO SETTLE FURTHER TO
THE SOUTH INTO THE OH VALLEY TODAY BEFORE BEGINNING TO LIFT
GRADUALLY BACK TO THE NORTH EARLY FRI.  ONGOING HEAVY
PRECIPITATION OCCURRING ACROSS PORTIONS OF THE MID ATLANTIC IS
EXPECTED TO CONTINUE INTO THE DAYLIGHT HOURS AS STRONG MOISTURE
ADVECTION AFFORDED BY DEEP UNIDIRECTIONAL FLOW INTERACTS WITH THE
LARGE SCALE FORCING EAST OF THE CENTER.  THE HEAVIEST AMOUNTS
THROUGH THE REMAINDER OF THE OVERNIGHT INTO THE EARLY DAY LIGHT
HOURS ARE EXPECTED TO FOCUS FROM CENTRAL NC TO THE SOUTHERN MD AND
THE DELMARVA AS MULTIPLE SHORTWAVES LIFTING EAST OF THE LOW
ENHANCE LIFT ALONG A SLOW MOVING FRONTAL BOUNDARY EXTENDING ACROSS
THE REGION.  INCREASING DIFFLUENT FLOW ALOFT IS EXPECTED TO
SUPPORT TRAINING CONVECTION...RAISING THE POTENTIAL FOR HEAVY
AMOUNTS.  AS THE LOW SETTLES FURTHER TO THE SOUTH TODAY...BACKING
FLOW ACROSS THE NORTHERN MID ATLANTIC STATES IS EXPECTED TO
SUPPORT STRONG MOISTURE ADVECTION...FUELING HEAVY RAINS ACROSS THE
UPSLOPE REGIONS ALONG THE NORTHERN MID ATLANTIC PIEDMONT INTO THE
CENTRAL APPALACHIANS...WHERE SEVERAL INCHES ARE POSSIBLE BY EARLY
FRI.  BY EARLY FRI WIDESPREAD AMOUNTS OF 2-4 INCHES OF RAIN...WITH
LOCALLY HEAVIER AMOUNTS ARE POSSIBLE ALONG THE NORTHERN VA...MD
AND SOUTHERN PA PIEDMONT WESTWARD INTO BLUE RIDGE AND ALLEGHENY
MOUNTAINS.  THESE AMOUNTS MAY RESULT IN EXCESSIVE RUNOFF AND FLASH
FLOODING CONCERNS.

...SOUTHWEST INTO THE CENTRAL ROCKIES...

A CLOSED LOW INITIALLY OVER SOUTHERN CALIFORNIA WILL CONTINUE TO
PUSH NORTHEASTWARD INTO THE GREAT BASIN ON THE SOUTHEASTERN SIDE
OF THE AMPLIFYING MID TO UPPER LEVEL TROF OFF THE PACIFIC
NORTHWEST COAST.  SCATTERED SHOWERS WILL CONTINUE IN THE AXIS OF
ABOVE AVERAGE PW VALUES STREAMING NORTHEASTWARD WITH THIS CLOSED
LOW FROM THE SOUTHWEST INTO THE GREAT BASIN.  CONFIDENCE IS LOW
WITH RESPECT TO THE DETAILS---WITH AREAL AVERAGE LIGHT TO MODERATE
AMOUNTS DEPICTED WITH ISOLATED HEAVY TOTALS POSSIBLE.  THESE
HEAVIER AMOUNTS MAY RESULT ISOLATED FLASH FLOODING CONCERNS AS
WELL.

PEREIRA
$$





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