Quantitative Precipitation Forecast
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445
FOUS30 KWBC 231414
QPFERD

EXCESSIVE RAINFALL DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1014 AM EDT SUN JUL 23 2017

...VALID 15Z SUN JUL 23 2017 - 12Z MON JUL 24 2017...
...REFERENCE AWIPS GRAPHIC UNDER...DAY 1 EXCESSIVE RAINFALL...


MARGINAL RISK OF RAINFALL EXCEEDING FFG TO THE RIGHT OF A LINE FROM
135 WNW MMHO 135 WSW OLS 60 S GBN 30 NNW GBN 45 WNW LUF
10 SSW IFP 35 ENE LSV 10 WNW SGU 55 SSW BCE 15 SE PGA 45 SSW 4BL
30 N CEZ 25 NE MTJ 25 WNW AFF 20 ESE PUB 10 ENE SPD 15 WNW PYX
15 SE GAG END 20 ENE GCM 10 WNW BPK 20 SSW UNO 40 ESE POF
20 S PAH 15 ESE PAH 15 SSW OWB 20 ENE OWB 20 ESE BAK 15 NNW WMO
LHQ 20 WSW HLG 20 N BVI 20 W ERI 25 SSE CWGD 15 ENE P58
10 SE PLN 35 NNW ERY 35 SSW CWXZ 25 SSE CYLD 40 SSE CYSB
20 SSW CWRK 10 S CWGH 35 SSW SLK 20 W GFL 25 NNW POU CDW
25 S FRG 50 S ISP 80 SE MJX 85 E OXB 65 SE MFV EDE 15 SSW OCW
20 SSE EQY 15 WNW CEU 20 NNE 8A0 15 SSE SRC 20 WNW MWT 30 N PRX
15 SSE DUA 30 SE SPS 30 SW F05 25 SSW AMA CVS 45 NE ROW
10 NW CNM 30 NNW MRF 60 S E38 130 SE MMCU.

MARGINAL RISK OF RAINFALL EXCEEDING FFG TO THE RIGHT OF A LINE FROM
40 WSW KCRH 25 NNE GLS 30 ENE IAH 45 WSW JAS 10 SSW JAS
20 N LFT 25 WNW MSY 10 NE BVE 15 S KMDJ.

MARGINAL RISK OF RAINFALL EXCEEDING FFG TO THE RIGHT OF A LINE FROM
55 SSE AAF 15 W 40J 15 W OCF 20 NNW LAL 25 E SRQ 25 SSE SRQ
65 SW SRQ 105 SW SRQ.

SLIGHT RISK OF RAINFALL EXCEEDING FFG TO THE RIGHT OF A LINE FROM
30 N MMHO 75 N MMHO 45 WSW OLS 25 WSW TUS 35 ESE IWA 40 NNE DVT
45 SE IGM 40 NNE IGM 60 W GCN 10 WNW 40G 30 WSW INW 15 SW SJN
30 E SJN 25 ESE GUP 45 S FMN 25 WSW CPW 20 NNW CPW 15 E ALS
20 SE VTP 25 ENE RTN 45 SE RTN 35 E LVS 20 SSE CQC 20 W 4CR
45 W 4CR 15 ESE ABQ 25 NNE AEG 25 SW AEG 65 SSW ABQ 30 ENE TCS
15 WNW ELP 60 NNW MMCU.

SLIGHT RISK OF RAINFALL EXCEEDING FFG TO THE RIGHT OF A LINE FROM
15 SSE HLG 10 ESE AFJ 20 SW JST 10 S CBE 15 ESE W99 15 WNW HSP
15 NW BKW 25 S HTS 20 ENE LEX 30 N FFT 15 NW CVG 10 SE WMO
20 SSW LHQ 25 N PKB 15 SSE HLG.


1500 UTC UPDATE

THE MARGINAL AND SLIGHT RISK AREAS WERE EXPANDED WESTWARD OVER THE
MID TO UPPER OH VALLEY FOR DEVELOPING CONVECTION AHEAD OF THE VORT
MOVING INTO THE LOWER OH VALLEY THIS MORNING.  THIS VORT SHOULD
CONTINUE TO PRESS EASTWARD TODAY THROUGH THE OH VALLEY AND INTO
THE CENTRAL APPALACHIANS BY EVENING AND INTO THE MID ATLANTIC
OVERNIGHT.  WITH FFG VALUES HAVING LOWERED OVER NORTHERN KY INTO
SOUTHERN OH AND CENTRAL TO NORTHERN WV FROM HEAVY RAINS OVER THE
PAST 24 HOURS---THE THREAT OF RUNOFF ISSUES HAS INCREASED. THE
LATEST HI RES GUIDANCE IS NOT HANDLING THIS FEATURE VERY
WELL--INCLUDING THE LATEST HRRR.  THE HRRR EXP IS SHOWING MORE QPF
AHEAD OF THIS FEATURE---ALTHOUGH LATEST IR IMAGERY IS SHOWING
WARMING TOPS.   SEE WPC`S MESOSCALE PRECIPITATION DISCUSSION #0542
VALID UNTIL APPROXIMATELY 1600 UTC FOR ADDITIONAL INFORMATION
ACROSS THE UPPER OH VALLEY INTO THE CENTRAL APPALACHIANS.
ELSEWHERE---NO CHANGES MADE TO THE PREVIOUS OUTLOOK AREA

ORAVEC


INITIAL DISCUSSION

GT LAKES...NORTHEAST..MID ATLC...TN VALLEY..WWD INTO THE SRN
PLAINS...

HEIGHTFALLS ASSOCD WITH A MID/UPR LEVEL TROF OVER THE WRN GT LAKES
AT THE BEGINNING OF THE DAY 1 PD WILL PUSH SLOWLY ESEWD THIS
PD..WITH SOME GRADUAL BACKING OF THE FLOW ACRS THE MID ATLC/NE BY
LATE SUN AND SUN NIGHT.  SOME SCTD SHWR/TSTM ACTIVITY AHEAD OF THE
MAIN HEIGHTFALLS WILL BE ONGOING AT THE BEGINNING OF THE PD AHEAD
OF AN ASSOCD SFC LOW OVER THE CNTL GT LAKES AS WELL AS ALONG A
QSNTY FRONT AND PREFRONTAL OUTFLOW BOUNDARY/TROF..BUT SHOULD
REALLY PICK UP AGAIN BY AFTN AND EVENING AS DAYTIME HEATING LEADS
TO STG INSTABILITY IN A RATHER MOIST AIRMASS.  PLENTY OF DETAIL
DIFFERENCES REMAIN IN THE 00Z MODEL GUIDANCE WHICH LEAD TO
SOMEWHAT LOWER CONFIDENCE IN THE QPF DETAILS.  THERE IS A SOMEWHAT
STGR MODEL SUPPORT IN DEPICTING ORGANIZED HEAVIER CONVECTIVE RAINS
FROM PARTS OF THE DE/MD/VA AREA NWD INTO NY LATE SAT/SAT NIGHT AS
APCHG SFC WAVE ENHANCES LIFT ALONG AND NORTH OF FRONT EXTENDING
EAST OF THE LOW.  HI RES RUNS SEEMS TO POINT TOWARD AREA FROM SRN
PA INTO NJ FOR HEAVIEST AXIS..BUT WITH THE EFFECTIVE FRONT
ASSOCIATED WITH THE DEEPER MSTR AND INSTABILITY BEING FORCED WELL
SOUTH BY SAT NIGHT CONVECTION QUESTIONS REMAIN AS TO HOW QUICKLY
THAT DEEPER MSTR AND INSTABILITY WILL RETURN NWD. FOR THAT
REASON..WILL REEVALUATE THIS AREA IN THE MORNING TO SEE IF AN
UPGRADE TO SLIGHT RISK OR HIGHER IS WARRANTED.   MDTLY HEAVY RAINS
WITH MORE ELEVATED CONVECTION WILL LIKELY EXTEND NWD INTO NY WITH
A STRENGTHENING JET ACRS NEW ENGLAND AIDING ASCENT.  ISOLD RUNOFF
ISSUES MAY OCCUR HERE LATE SUN/SUN NIGHT.    FARTHER TO THE SOUTH
AND WEST...MDTLY HEAVY RAINS ARE ALSO EXPECTED TO FROM PARTS OF
WV/VA WWD THROUGH THE TN VALLEY INTO OK/TX REGION WITH POTNL FOR
ISOLD POCKETS OF VERY HEAVY RAIN GIVEN PWS OVER 2 INCHES AND POTNL
FOR SOME TRAINING ELEMENTS..PRIMARILY ACRS THE TN VALLEY AND AREAS
EAST.  HAVE HIGHLIGHTED A SLIGHT RISK FOR PORTIONS OF WV INTO THE
WRN MD PANHANDLE GIVEN THE EXISTING VERY LOW FLASH FLOOD GUIDANCE
VALUES.

  ..SOUTHWEST U.S. INTO THE SOUTHERN ROCKIES...

MONSOONAL MOISTURE WILL REMAIN ABUNDANT FROM NORTHWEST
MEXICO--NORTHWARD INTO THE DESERT SOUTHWEST AND NORTHEASTWARD INTO
THE SOUTHERN ROCKIES DAY 1.  THIS WILL SUPPORT ANOTHER DAY OF
WIDESPREAD SCATTERED CONVECTION---WITH LOCALLY HEAVY TOTALS AND
ISOLATED RUNOFF ISSUES.  MODEL CONSENSUS FOR THE MOST CONCENTRATED
AREA OF MODERATE TO HEAVY RAINS CONTINUES FROM IN THE VICINITY OF
SOUTHEAST AZ/SOUTHWEST NM/FAR SOUTHWEST TX REGION IN THE VICINITY
OF SLOW MOVING MID TO UPPER LEVEL VORT FEATURES OVER NORTHWEST
MEXICO.  A SLIGHT RISK OF EXCESSIVE RAINS WAS DEPICTED FOR MUCH OF
THE MOGOLLON RIM AREA SEWD INTO SE AZ/SW NM AND ALSO OVER PORTIONS
OF THE SAN JUANS OF SRN CO INTO NRN NM.

...CENTRAL TO EASTERN GULF COAST...

A MID TO UPPER LEVEL CLOSED LOW EMBEDDED IN RATHER WEAK FLOW ALOFT
IS EXPECTED TO MEANDER NEAR THE LA COAST THIS PD.  EXPECT STORMS
TO FIRE FAIRLY EARLY IN THE DAY NEAR THE UPPER LOW AS VERY DEEP
MSTR WITH PWS NEAR 2.25 INCHES EXPAND ACRS THE UPPER TX COAST INTO
SRN LA UNDER SW LOW LEVEL FLOW OFF THE GULF OF MEXICO.  SOME MDT
TO LOCALLY HEAVY RAINS ARE EXPECTED HERE ESPECIALLY ALONG SEA
BREEZE THAT SHOULD EXPAND NWD DURING THE DAY. ISOLD FLASH FLOODING
MAY BE PSBL.   HI PWS REMAIN EWD INTO FL WHERE SCTD PRIMARILY
DIURNAL TSTM ACTIVITY IS EXPECTED..THAT WILL BE ACCOMPANIED BY
LOCALLY HEAVY DOWNPOURS AT TIMES. IN BOTH AREAS...HAVE INDICATED A
MARGINAL RISK OF FLASH FLOODING.

SULLIVAN
$$





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