Quantitative Precipitation Forecast
Issued by NWS

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FOUS30 KWBC 191442
QPFERD

EXCESSIVE RAINFALL DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1041 AM EDT MON JUN 19 2017

...VALID 15Z MON JUN 19 2017 - 12Z TUE JUN 20 2017...
...REFERENCE AWIPS GRAPHIC UNDER...DAY 1 EXCESSIVE RAINFALL...


MARGINAL RISK OF RAINFALL EXCEEDING FFG TO THE RIGHT OF A LINE FROM
100 SE WAL 15 SE 9W7 20 NNW EWN 20 WNW ILM 20 NW CRE 20 NNE CHS
20 NNW SAV 15 NE AYS 10 SSE NIP 20 NE OCF 15 SSW TIX 10 SSW SUA
FXE 25 E HST 40 E MTH 35 NNW MTH 15 SSW SPG 75 SW CTY 10 W PAM
30 N ECP 15 NNE BGE 35 N ABY 10 ENE MCN 25 WNW MLJ 15 WNW OPN
25 ESE MXF 25 NW GZH 25 NW MOB NEW 20 ESE ARA 10 SW ACP
40 NNE JAS 40 N JAS 10 WSW OCH 10 NNW LHB 20 WSW GTU 20 NW 6R9
35 SSE ABI 15 E SWW 35 N DYS 20 NNW MWL 25 N GVT 10 NW OSA
35 NW DTN 35 SSW ELD 20 ENE BQP 30 NNE JAN 25 ESE GTR 20 SE HSV
35 WNW RHP 25 NNE OQT 15 NNW LNP 35 S HTS 25 E HTS 15 NW MGW
10 NE DUJ 25 ESE ELZ 15 N BGM 25 SE UCA 30 N GFL 15 NE CWFQ
25 WSW CWHV 30 ESE CWST 45 NE CERM 50 E PQI 25 SSW CWSS PSM
10 SW OQU 65 SSE FOK.

SLIGHT RISK OF RAINFALL EXCEEDING FFG TO THE RIGHT OF A LINE FROM
SEG 30 N AVP 45 SSE UCA GFL 20 WSW MPV 15 NE CYSC 50 ENE CWHV
15 ENE CERM 35 E PQI 15 SE MLT NHZ CEF 10 S JFK 20 NW ACY
15 NW GED 10 W SBY FYJ 10 SSW SFQ JNX 15 SW 45J 20 SSE GRD
10 N IIY 15 SE AND 10 SE EHO 15 NE FQD 15 ESE TNB 10 W MWK
15 E MTV 25 N DAN 10 ENE LYH 20 S CHO 10 WSW SHD 20 N SHD
15 ESE OKV 15 WSW HGR SEG.



...A SLIGHT RISK OF EXCESSIVE RAINS IS EXPECTED FOR PORTIONS OF
THE EAST COAST FROM NEW ENGLAND SOUTHWARD THROUGH THE MID ATLC
INTO SOUTHEAST..

15Z UPDATE...

WPC MADE MODEST ADJUSTMENTS TO THE EXCESSIVE RAINFALL FORECAST
VALID FOR THE NEXT 21 HRS. THE SLIGHT RISK STILL REMAINS VERY
LIKELY LATER THIS AFTERNOON THROUGH THE OVERNIGHT HRS FROM NEW
ENGLAND SOUTH INTO PARTS OF THE CAROLINAS. A PRONOUNCED SURFACE
COLD FRONT WILL INTERACT WITH A VERY ANOMALOUS AIR MASS FOR LIKELY
CONVECTIVE ACTIVITY AND OPPORTUNISTIC RAIN RATES. THE ONLY
ADJUSTMENT BASED ON THE HI-RES PACKAGE OVERNIGHT WAS TO SHIFT THE
SOUTHERN EDGE A LITTLE WEST AND SOUTH INTO WESTERN NC AND PART OF
UPSTATE/CENTRAL SC. MEANWHILE ADJUSTMENTS TO THE MARGINAL THREAT,
WPC CUT THE WESTERN EDGE FROM NY STATE TO WV, EXPANDED THE AREA
ACROSS EAST CENTRAL TX NEAR DFW METRO AREA WITH ONGOING ACTIVITY
AND EXTENDED/INTRODUCED A THREAT ACROSS PARTS OF THE FL
PENINSULA/PANHANDLE. THE LATTER IS IN RESPONSE TO THE MOIST SERLY
ONSHORE FLOW OR THE VERY OUTER PERIPHERY OF THE BROAD AREA OF LOW
PRESSURE OVER THE GULF OF MEXICO. THE OVERNIGHT HI-RES SUITE
FOCUSED LOCALLY HEAVY RAINS FROM SOUTH FL NORTHWEST TO THE NRN FL
PENINSULA/APALACHICOLA BAY REGION, WHICH IS ALREADY BEGINNING AND
COULD PERSIST WITH POSSIBLE TRAINING AND LOCALLY ENHANCED RAINS.

MUSHER



PREV DISCUSSION...

WIDESPREAD MODERATE TO HEAVY CONVECTIVE RAINS ARE LIKELY THIS
PERIOD ALONG AND AHEAD OF A STRENGTHENING COLD FRONT THAT IS
EXPECTED TO PUSH EWD FROM THE OH VALLEY INTO THE NE/MID ATLC
BEFORE SLOWING SWWD ACRS THE LOWER MS VALLEY BY TUES MORNING.
MODELS SHOW SUPPORTING UPPER TROF THROUGH THE MIDWEST SHARPENING A
BIT ON MON AS ADDITIONAL JET ENERGY DIGS INTO THE WEST SIDE OF THE
TROF WITH UPPER FLOW BACKING SLIGHTLY ACROSS THE MIDATLC INTO THE
NORTHEAST.  VERY FAVORABLE MOISTURE/INSTABILITY PROFILES ARE
EXPECTED AHEAD OF THE FRONT ESPECIALLY FROM THE MIDATLC REGION NWD
WHICH SHOULD ALLOW RAPID DVLPMENT OF FRONTAL/PREFRONTAL CONVECTION
ESPECIALLY DURING PEAK HEATING MON AFTERNOON/EVENING..WITH SOME
SLOW MOVING CONVECTIVE LINES LIKELY TO OCCUR..ESPECIALLY ALONG THE
ADVANCING COLD FRONT THAT COULD LEAD TO INTENSE RAIN RATES AND
LOCALIZED FLASH FLOODING.  BY MON NIGHT...THERE IS A MODERATELY
HIGH CONSENSUS IN THE 00Z HI RES MODEL RUNS TO SUGGEST A SLOWING
OF THE EXPECTED CONVECTIVE LINE THROUGH SE VA SWWD INTO THE CNTL
NC WITH SOME INTENSE RAIN RATES PSBL AS LINE BECOMES COINCIDENT
WITH VERY DIFFLUENT UPPER FLOW OVER THE REGION.  THERE IS FAIRLY
DECENT SUPPORT IN THE HIGH RES GUIDANCE FOR A SWATH OF 1 TO 2"
PLUS AMOUNTS FROM PARTS OF MAINE SWD INTO THE MID ATLC WITH
EMBEDDED AREAS OF LOCALIZED RAIN IN EXCESS OF 4 INCHES IN SEVERAL
HOURS.    CHANGES FROM CONTINUITY WERE RELATIVELY MINOR..THOUGH
DID INCREASE AMOUNTS FROM SE VA SWWD INTO NC GIVEN THE STRONGER
CONSENSUS WITH THE HI RES GUIDANCE SUPPORTING SLOW TRAINING
CONVECTION THERE MON NIGHT.  FARTHER SOUTH...FRONT WILL GRADUALLY
SINK SOUTHWARD INTO AN UPPER LEVEL COL REGION FROM TEXAS EWD INTO
THE LOWER MS VALLEY.  PLENTY OF MSTR WILL REMAIN ALONG THE FRONT
WITH PWS EXPECTED TO BE AOA 2.0 INCHES.  WHILE CONFIDENCE IN QPF
DETAILS HERE WILL BE QUITE LOW GIVEN ACTIVITY WILL BECOME
INCREASINGLY MESOSCALE DRIVEN...SOME LOCALLY HEAVY RAINS WILL BE
PSBL IN SOME OF THE STGR/SLOW MOVING CELLS AND CELL MERGERS WITH
AN ISOLATED FLASH FLOOD RISK NOT OUT OF THE QUESTION.

SULLIVAN

$$




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