Quantitative Precipitation Forecast
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000
FOUS30 KWBC 222220
QPFERD

EXCESSIVE RAINFALL DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
619 PM EDT SAT JUL 22 2017

...VALID 2219Z SAT JUL 22 2017 - 12Z SUN JUL 23 2017...
...REFERENCE AWIPS GRAPHIC UNDER...DAY 1 EXCESSIVE RAINFALL...


MARGINAL RISK OF RAINFALL EXCEEDING FFG TO THE RIGHT OF A LINE FROM
40 SW OLS 40 WSW OLS 30 S CGZ GEU 25 WSW PRC 30 NE IGM SGU
15 NW CDC 25 ESE MLF 50 ENE MLF 50 WNW 4HV 35 WNW 4HV 35 WSW 4HV
40 E BCE 35 ESE BCE 20 NW PGA 15 SSE PGA 50 SE PGA 70 SE PGA
50 NE INW 40 NNE RQE MTJ 25 W APA 25 SSE AKO 20 W CNK 20 W IRK
30 ESE MQB OKK 10 ENE HZY ELZ 25 NW POU 10 NNE GON 40 SSE MTP
75 ESE MJX 45 E OXB 10 SSW WAL 15 SSE CJR 20 ESE ROA 10 E MRN
15 NE CEU 30 S RHP 30 W RHP TYS 10 NE 1A6 35 NNW LOZ 30 S OWB
CGI 45 ESE TBN 10 SSE SGF 15 WSW CNU 20 WNW ICT 35 WNW AVK
20 SE PPA 25 ENE LBB 35 SSE BPG 50 E 6R6 65 S 6R6 95 SSW 6R6
125 SSW 6R6.

SLIGHT RISK OF RAINFALL EXCEEDING FFG TO THE RIGHT OF A LINE FROM
55 SSW DUG 15 SSW OLS 40 N DMA 35 ENE FFZ 25 E PRC 25 ENE PRC
15 W FLG 20 ENE FLG 25 N SOW 35 ENE SJN 15 W GNT 25 NNW 4SL
25 E DRO 15 S GUC 35 SE LXV 15 E COS 20 SSW LHX 35 NW CAO
50 WSW CAO 10 SW LVS 25 S CQC SRR 40 SE ALM 40 SW GDP
90 SSE MMCS 80 S MMCS.

SLIGHT RISK OF RAINFALL EXCEEDING FFG TO THE RIGHT OF A LINE FROM
20 NE FFT 30 NE HNB RSV 20 NNE HUF 20 NNW WMO 15 NNE ZZV
15 SE BTP 15 SSE IPT 10 SSE FRG 55 E MJX ILG FDK SHD BCB
10 ENE MKJ 15 NW 6V3 20 SW HTS 20 NE FFT.


2200 UTC UPDATE...

MINOR CHANGES WERE MADE TO THE DAY 1 ERO...WHICH INCLUDED
RESHAPING THE SLIGHT RISK AREA ACROSS THE OH VALLEY-NORTHERN MID
ATLANTIC REGION TO ALIGN WITH THE LATEST COMPOSITE RADAR IMAGERY
AND MESOANALYSIS TRENDS...WHILE ALSO INCORPORATING THE MORE RECENT
HRRR/EXPERIMENTAL HRRR OUTPUT AND TRENDS. IN
ADDITION...OROGRAPHICALLY-AIDED SLOW-MOVING/PULSE CONVECTION
ACROSS WEST TX WILL NECESSITATE A MARGINAL RISK THROUGH THIS
EVENING GIVEN MODEST AVAILABLE DEEP LAYER INSTABILITY (MIXED LAYER
CAPES 1000-2000 J/KG) ALONG WITH THE 1.50+ PWAT ENVIRONMENT...AS
LOCALIZED RAINFALL RATES OF 2-2.5 INCHES WITHIN A COUPLE OF HOURS
WILL BE POSSIBLE.

HURLEY


1500 UTC UPDATE

THE ONLY CHANGE OF NOTE FROM THE PREVIOUS EXCESSIVE RAINFALL
POTENTIAL OUTLOOK WAS THE REMOVAL OF THE MARGINAL RISK AREA OVER
THE GREAT LAKES REGION.  MODEL CONSENSUS IS FOR GREATEST THREAT OF
HEAVY RAINS TO REMAIN SOUTH OF THE GREAT LAKES FROM THE MID
ATLANTIC---WESTWARD INTO THE OH VALLEY---CENTRAL PLAINS INTO THE
SOUTHERN HIGH PLAINS AND SOUTHWEST.

ORAVEC



INITIAL DISCUSSION

...MID ATLC WWD THROUGH THE OH AND MID MS VALLEYS AND CNTL
PLAINS...

  ...SLIGHT RISK OF EXCESSIVE RAINS OR PARTS OF THE OH VALLEY EWD
INTO THE NRN MID ATLC...

NUMEROUS SHOWERS AND TSTMS ARE EXPECTED TO SPREAD EWD FROM ONGOING
EARLY MORNING CONVECTION/MCS ACROSS PARTS OF THE MIDWEST/OH VALLEY
ASSOCD WITH A WEAK AREA OF LOW PRES AND CONVECTIVELY ENHANCED
S/WV...STRADDLING AN E/W FRONTAL BNDRY.  VERY DEEP MSTR WITH PWS
AOA 2 INCHES ARE EXPECTED TO POOL ALONG THE BNDRY..MAXIMIZING ACRS
PARTS OF THE MID ATLC EAST OF THE APLCNS SAT AFTN.   MODELS
SUGGEST A RE-INTENSIFICATION OF REMNANT MCS ACTIVITY AS IT MOVES
INTO PA/WV AND POINTS EAST BY AFTN AS DAYTIME HEATING AWAY FROM
DENSER OVERCAST ALLOWS FOR STG DESTABILIZATION OF THE AIRMASS.
MODEL PREFERENCE WISE...GLOBAL MODEL RUNS WERE CERTAINLY TOO FAR
NORTH WITH HEAVIER CONVECTIVE RAINS ACRS THE MIDWEST ON FRI/FRI
NIGHT AND THAT MAY BE AGAIN THE CASE TODAY.  HI RES GUIDANCE
ESPECIALLY THE EXPERIMENTAL HRRR HAS AT LEAST CAPTURED THE
EVOLUTION OF MCS ACTIVITY ACRS THE MIDWEST REASONABLY WELL AND
THAT TOGETHER WITH THE NAM CONEST AND EVEN THE WRF ARW APPEAR TO
BE A GOOD BLEND FOR DOWNSTREAM DVLPMENT TODAY.  THAT WOULD SUGGEST
HEAVIEST RAIN AXIS WITH AREAL AVG AMOUNTS IN EXCESS OF AN INCH
ACRS PARTS OF SE OH INTO MUCH OF SRN PA..SRN NJ INTO NRN MD AND
NRN WV...WITH DEEPER LAYERED WLY FLOW SUGGESTING DECENT CHANGE OF
TRAINING AND BOWING LINE SEGMENTS PSBLY LEADING TO FLASH FLOODING.
GIVEN THE VERY HIGH PWS..LOCAL RAINFALL RATES EXCEEDING 2 INCHES
PER HOUR WILL BE PSBL.   BEHIND THE MAIN WAVE...DEEP MSTR WILL
REMAIN POOLED ALONG THE BNDRY EXTENDING WWD THRU THE MIDWEST/MID
MS VALLEY AND CNTL PLAINS WITH VERY UNSTABLE CONDS EXPECTED WHICH
SHOULD LEAD TO SCTD CONVECTION ALONG THE BNDRY INTO SAT NIGHT.
SOME EMBDD SMALLER SCALE MCS ACTIVITY WILL BE PSBL WHICH COULD
LEAD TO ISOLD HEAVIER CONVECTIVE RAINS ALONG THE BNDRY FROM THE
CNTL PLAINS INTO THE MID MS VALLEY AIDED BY WEAK S/WV ENERGY
EJECTING OUT OF THE CNTL ROCKIES.  HOWEVER CONFIDENCE IN QPF
DETAILS HERE ARE LOWER AND THUS HAVE TAKEN MORE OF AN ENSEMBLE
APCH TO QPF ACROSS THIS AREA.


...SOUTHWEST/GREAT BASIN/CENTRAL ROCKIES...

  ...SLIGHT RISK OF EXCESSIVE RAINS FROM SE AZ/SW NM NEWD INTO SRN
CO...

WHILE SLIGHT UPPER RIDGING IS FCST ACRS THE GT BASIN THIS PD
OVERALL 5H PATRN REMAINS VERY WEAK WITH LITTLE STEERING FLOW.
ACRS THE 4 CORNERS REGION...LITTLE CHANGE IS EXPECTED TO THE
OVERALL MSTR PROFILES WITH PERHAPS SOME SLIGHT INCREASE IN OVERALL
PWS ACRS SRN PORTIONS OF AZ DURING THE PD.  SCTD DIURNALLY
ENHANCED CONVECTION WILL ONCE AGAIN BE THE RULE ACRS THIS REGION.
WEAK UPPER SHEAR AXIS NOTED ACRS WRN CO MAY LEAD TO SOME SLIGHTLY
HEAVIER ORGANIZED RAIN AMOUNTS ACRS PARTS OF SRN CO INTO NRN
NM..WHILE HAVE INDICATED SOMEWHAT HEAVIER QPF TOTALS ACRS SERN
AZ/SW NM IN AREA OF WEAK 85H-7H CONFLUENCE.  PATRN WILL AGAIN
SUPPORT THE POTNL FOR FLASH FLOODING ACRS PARTS OF THE
REGION..ESPECIALLY ACROSS BURN SCAR AREAS AND NEAR STEEPER TERRAIN
WITH GREATEST RISK OF FLASH FLOODING FROM SE AZ/SW NM NEWD INTO
SRN CO WHERE A SLIGHT RISK OF EXCESSIVE RAINS HAS BEEN PLACED.


SULLIVAN
$$




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