Quantitative Precipitation Forecast
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032
FOUS30 KWBC 240059
QPFERD

EXCESSIVE RAINFALL DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
858 PM EDT SUN JUL 23 2017

...VALID 01Z MON JUL 24 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
70 ESE MJX 15 NNE GED 20 NNW MTN 15 NW FDK 25 S OKV 20 ESE HSP
10 WSW MKJ 35 SSE CSV 10 NW MSL 35 SE UTA 20 S PBF 10 NNW TXK
20 NNE TKI SPS 10 NNE HBR 30 NW CHK MLC 30 NNW MWT 15 SSW BYH
35 S GLW 35 W LNP 10 NNW I16 10 NNE CRW 20 WSW UNI 10 SSE WMO
15 SSE AID 15 S FWA 20 NW MFD 10 NW FKL 15 NNE DSV 15 W RME
20 W SCH POU 10 S FOK 70 ESE MJX.

MARGINAL RISK OF RAINFALL EXCEEDING FFG TO THE RIGHT OF A LINE FROM
130 WNW MMHO 90 S GBN 20 SE GBN 10 WSW LUF 40 SSW PRC 25 S IGM
30 NNW IFP 40 ENE LSV 15 SSW SGU 60 W PGA 35 SSW PGA 40 NNE INW
15 SW GUP 70 NW TCS 15 WNW HMN 10 NNE GDP 30 N E38 50 S MRF
50 ENE MMCU.

MARGINAL RISK OF RAINFALL EXCEEDING FFG TO THE RIGHT OF A LINE FROM
65 ESE FFA 10 SSE MQI OCW 20 S DPL 35 S FLO 35 NNE JYL
10 SE MLJ 25 ENE OPN 25 ESE ATL 10 ESE WDR 15 W CAE 15 NW UDG
15 NNE HRJ 20 WNW EDE 10 SE 9W7 65 ENE FFA.

SLIGHT RISK OF RAINFALL EXCEEDING FFG TO THE RIGHT OF A LINE FROM
75 N MMHO 75 SW OLS 70 W OLS 35 WNW TUS 10 ENE FFZ 25 SW PRC
10 SE IGM 30 NNW IGM 50 E LSV 55 SSE SGU 10 ENE FLG 25 WSW SOW
35 N SAD 25 NW SVC 50 SW DMN 80 S DMN 110 SW MMCS 110 SE DUG.

SLIGHT RISK OF RAINFALL EXCEEDING FFG TO THE RIGHT OF A LINE FROM
15 NNE BVI BFD 15 S PEO 20 SSW UCA 40 WSW SCH MGJ 10 SSW ISP
40 ESE MJX 15 SW ACY 15 NNW ILG MDT 15 E CBE 20 N HSP 30 S 48I
25 SSW PKB 15 S LHQ 10 W DAY AOH 15 NNE BVI.


0100 UTC UPDATE

LATEST ERO LARGELY REFLECTS THE LATE-DIURNAL MESOANALYSIS AND
CONVECTIVE TRENDS...WHILE INCORPORATING THE MOST RECENT SOIL
MOISTURE ANALYSIS FROM THE NATIONAL WATER MODEL AND FFG FROM THE
RFC/S. ONE OF THE TWO MAIN AREAS OF A MORE ENHANCED THREAT
("SLIGHT RISK") INCLUDE THE OH VALLEY INTO PA/NY SOUTHERN
NY...AHEAD OF THE APPROACHING SHORTWAVE TROUGH WHERE THE ALIGNMENT
OF THE LOW-LEVEL FLOW AND MEAN 850-300 MB FLOW WILL FAVOR TRAINING
OF CONVECTION THIS EVENING. GIVEN THE WEAK LAPSE RATES ALOFT...
THE DEEP-LAYER INSTABILITY (LARGELY DIURNALLY-DRIVEN) WILL
CONTINUE TO WEAKEN AFTER SUNSET. HOWEVER...INCREASING DYNAMICAL
FORCING AHEAD OF THE SHORTWAVE AND WITHIN THE RIGHT ENTRANCE
REGION OF THE UPPER JET STREAK OVER UPSTATE NEW YORK-NORTHERN NEW
ENGLAND WILL MAINTAIN MORE NUMEROUS CLUSTERS OF CONVECTION WELL
INTO THE EVENING/EARLY OVERNIGHT HOURS AS THE 850 MB INCREASES TO
25-30 KTS. WITHIN THE SLIGHT RISK AREA...THE LATEST (00Z BASED)
HOURLY FFG IS BETWEEN 1-1.5".

THE OTHER SLIGHT RISK AREA CONTINUES JUST WEST OF THE DEEP-LAYER
RIDGE ACROSS AZ ALONG AND SOUTH OF THE MOGOLLON RIM...INTO
SOUTHEAST AZ AND SOUTHWEST NM WHERE OROGRAPHY CONTINUES TO ENHANCE
THE COVERAGE AND INTENSITY OF THE MONSOONAL RAINS.

HURLEY


1900 UTC UPDATE

CHANGES TO THE PREVIOUS EXCESSIVE RAINFALL OUTLOOK WERE TO EXPAND
THE SLIGHT RISK AREA CENTERED OVER THE CENTRAL APPALACHIANS/UPPER
OH RIVER VALLEY REGION NORTHEASTWARD INTO NORTHEASTERN
PA---NORTHERN NJ AND INTO PORTIONS OF THE SOUTHERN TIER OF NY
STATE ALONG THE NORTHEAST PA BORDER REGION.  THIS WAS TO COVER
CONVECTION POTENTIAL AHEAD OF THE VORT MOVING EAST NORTHEASTWARD
FROM THE UPPER OH VALLEY INTO THE MID ATLANTIC.  SCATTERED
CONVECTION IS BEGINNING TO DEVELOP FROM THE SOUTHERN TIER OF NY
STATE INTO THE MID ATLANTIC AHEAD OF THIS VORT.  WITH FFG VALUES
RELATIVELY LOW ACROSS THESE REGIONS---ISOLATED RUNOFF ISSUES
POSSIBLE WITH THE DEVELOPING CONVECTIVE CELLS.  PLEASE SEE WPC`S
MESOSCALE PRECIPITATION DISCUSSION # 0544 VALID UNTIL 2325 UTC FOR
ADDITIONAL INFORMATION ACROSS THE SOUTHERN TIER OF NY STATE AND
NORTHERN PA.   THE SLIGHT RISK AREA WAS TRIMMED TO THE EAST OVER
THE UPPER OH VALLEY TO REFLECT EXPECTED AXIS OF HEAVIEST PRECIP
AHEAD OF THE ABOVE MENTIONED VORT MOVING OUT OF THE UPPER OH
VALLEY.


ORAVEC


INITIAL DISCUSSION

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

HEIGHT FALLS 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 HEIGHT FALLS 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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