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

000
FOUS30 KWBC 171451
QPFERD

EXCESSIVE RAINFALL DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1050 AM EDT SAT JUN 17 2017

...VALID 15Z SAT JUN 17 2017 - 12Z SUN JUN 18 2017...
...REFERENCE AWIPS GRAPHIC UNDER...DAY 1 EXCESSIVE RAINFALL...


MARGINAL RISK OF RAINFALL EXCEEDING FFG TO THE RIGHT OF A LINE FROM
35 W CYWA 20 NNW CYKF DET 20 WSW DFI 20 SSW PRG 20 WSW POF
20 WNW GMJ 30 NNW WDG 10 NNW ICT 25 NNE EMP 10 ESE LWC 25 SW CDJ
15 SW OTM MXO 15 SW OSH 15 SW MNM 15 ENE ESC 50 S CYLD
40 SSW CYTS.

MARGINAL RISK OF RAINFALL EXCEEDING FFG TO THE RIGHT OF A LINE FROM
30 N KVKY 30 NNW HSA 30 S JAN 40 E JAN 30 SSE MEI 35 SW MGM
20 S TOI 15 NW BGE 20 NE PAM 60 SSW DTS.

MARGINAL RISK OF RAINFALL EXCEEDING FFG TO THE RIGHT OF A LINE FROM
20 WNW MTV 10 NE UKF MRN 20 NW FQD 15 NW AVL 35 NNW AVL
10 NNE VJI BKW 15 WNW 2G4 15 SE LBE 10 NNE JST AOO 25 WNW HGR
OKV 10 NW KW66 10 ESE CHO 30 SSW SHD 20 NE MTV 20 N GSO
20 WNW MTV.

SLIGHT RISK OF RAINFALL EXCEEDING FFG TO THE RIGHT OF A LINE FROM
15 NE MPZ 20 ESE VYS 30 NW GUS 20 ENE DNV 15 NNE TAZ IRK
15 NE MPZ.


1500 UTC UPDATE

CHANGES TO THE PREVIOUS EXCESSIVE RAINFALL POTENTIAL OUTLOOK WERE
TO ADD A MARGINAL RISK AREA ACROSS PORTIONS OF THE APPALACHIANS
FROM NORTHWEST NC/FAR NORTHEAST TN INTO SOUTHWEST VA---EASTERN
WV---NORTHWEST VA---FAR WESTERN MD INTO SOUTHWEST PA.  EXPECT
ADDITIONAL SCATTERED CONVECTIVE POTENTIAL ACROSS THESE AREAS THIS
AFTERNOON AS CLOUDS DECREASE...INCREASING INSTABILITY.  THIS ALONG
WITH LOWERED FFG VALUES FROM HEAVY RAINS OVER THE PAST 24 HOURS
WILL SUPPORT AT LEAST A MARGINAL RISK OF RUNOFF ISSUES FROM
LOCALLY HEAVY RAINS---1.5-2" PER HOUR---TOTALS OF UP TO 3"---
LATER THIS AFTERNOON.  THE NEIGHBORHOOD PROBABILITIES FROM THE HI
RES ARW---NMMB---NAM CONEST AND SSEO MEAN ALL SHOW A SIGNAL FOR
POTENTIALLY EXCESSIVE RAINFALL AMOUNTS ACROSS THESE AREAS---WITH
PROBABILITIES OVER 40-50%.  PLEASE SEE WPC MESOSCALE PRECIPITATION
DISCUSSION  #0332 VALID UNTIL APPROXIMATELY 2100 UTC FOR
ADDITIONAL DETAILS ACROSS THIS AREA.

ORAVEC




INITIAL DISCUSSION

NORTHERN PLAINS/GT LAKES SOUTHWARD INTO THE CNTL PLAINS/MID MS
VALLEY...

A NORTHERN STREAM S/WV WILL DIG SOUTHEASTWARD FROM THE NRN
INTERMOUNTAIN REGION EARLY SATURDAY WITH ASSOCD HEIGHT FALLS
SUPPORTING LOW PRESSURE DEVELOPMENT ALONG AN INTENSIFYING COLD
FRONT OVER THE MO VALLEY THAT WILL LIFTING NEWD SAT NIGHT TOWARD
THE GT LAKES.   THE COMBINATION OF STG HEIGHT FALLS AND..POOLING
OF 2 INCH PWS ALONG THE FRONT AND STEEPENING LAPSE RATES SHOULD
SUPPORT RAPID INTENSIFICATION OF THUNDERSTORMS MOST NOTABLY ACROSS
ERN IA/NRN MO AND THE NRN PORTION OF IL BY LATE SAT.  THESE STORMS
SHOULD CONTINUE TO EXPAND IN COVERAGE WITH FAVORABLE SHEAR AND
MOISTURE PROFILES LIKELY SUPPORTING ORGANIZED SQLN DEVELOPMENT
THAT WILL EXPAND SOUTH AND EAST OVERNIGHT.  THE NAM WAS A BIT MORE
DVLPD BOTH WITH THE S/WV TROF AND ASSOCD SFC LOW WHICH RESULTED IN
IT PLACING ITS HEAVIER EMPHASIS FARTHER NORTH.  THE CONSENSUS OF
THE WRF ARW..NMM..AND CANADIAN GEM INDICATED A POTNL E/W FOCUS OF
HEAVIER RAINS SOUTH OF THE NAM AND MORE ACROSS CNTL IL INTO SE
IA/NE MO WHERE E/W ALIGNMENT OF THE FRONT EAST OF THE LOW WILL BE
CONDUCIVE FOR TRAINING AND PSBL ELEVATED RISK OF EXCESSIVE RAINS
EARLY SAT NIGHT AND HAVE INTRODUCED A SLIGHT RISK ACROSS THIS
REGION.  POTNL WILL EXIST HERE FOR ISOLD 3 TO 5 INCH IN RAINS IN A
COUPLE HOURS.   ACCELERATION OF POTNL SQLN TO THE SOUTH ACRS KS/MO
INTO OK/AR IS EXPECTED SAT NIGHT TOWARD MORE FAVORABLE
INSTABILITIES WITH AMPLIFYING NWLY FLOW AND WILL LIKELY SEE SOME
INTENSE BUT SHORTER LIVED RAIN RATES GIVEN THE FAVORABLE
MSTR/INSTABILITY PROFILES. STILL COULD NOT RULE OUT ISOLD RUNOFF
ISSUES WHERE BOWING PORTION OF LINE MAY BRIEFLY SLOW OR HANG UP.
FARTHER NORTH...STEEPENING LAPSE RATES AHEAD OF MAIN CORE OF
HEIGHT FALLS ACRS THE NRN PLAINS INTO THE WRN GT LAKES WILL
SUPPORT MDT CONVECTIVE RAIN AMOUNTS THERE..WHILE AN UPTICK IN
CONVECTION IS ALSO EXPECTED AHEAD OF THE DEEPENING SFC WAVE SAT
AFTN/NIGHT FROM PORTIONS OF ERN WI EWD INTO LOWER MI.  HI RES
GUIDANCE SUGGEST SOME SOME HEAVIER RAIN AMOUNTS OF BETWEEN 1 TO 2
INCHES OVER PORTIONS OF LOWER MI WITH MEAN LAYER FLOW PARALLELING
THE SFC FRONT SUPPORTING POTNL TRAINING.  THESE AMOUNTS COULD
APPROACH SOME OF THE LOWER FFG VALUES ESPECIALLY OVER ERN PORTIONS
OF THE LOWER PENINSULA.

CNTL GULF COAST/FL PANHANDLE...

A FAIRLY ORGANIZED CONVECTIVELY INDUCED MID LEVEL LOW IS FCST TO
SLOW AND MEANDER NEAR THE GULF COAST IN VCNTY OF THE AL/FL REGION
THIS PD AS IT MOVES INTO A REGION OF RELATIVELY WEAK STEERING
FLOW.   THERE WILL REMAIN THE POTNL FOR LOCALIZED HEAVIER RAINS
NEAR THE UPPER LOW THROUGH THE PD AS MOIST SWLY LOW LEVEL FLOW
MAINTAINS MDTLY HIGH PWS ACRS THE REGION WITH WEAK CYCLONIC FLOW
ALOFT.  ISOLD RUNOFF ISSUES WILL BE PSBL FROM SE MS THROUGH SRN AL
AND PORTIONS OF THE FL PANHANDLE ESPECIALLY IN AREAS WHERE
ANTECEDENT CONDS INDICATE MOIST SOIL CONDS FROM RECENT RAINS.

SULLIVAN

$$





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