Quantitative Precipitation Forecast
Issued by NWS

Current Version | Previous Version | Graphics & Text | Print | Product List | Glossary On
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
000
FOUS30 KWBC 210335
QPFERD

EXCESSIVE RAINFALL DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1133 PM EDT THU APR 20 2017

...VALID 0100Z FRI APR 21 2017 - 12Z FRI APR 21 2017...
...REFERENCE AWIPS GRAPHIC UNDER...DAY 1 EXCESSIVE RAINFALL...


MARGINAL RISK OF RAINFALL EXCEEDING FFG TO THE RIGHT OF A LINE FROM
15 SSW DUJ 10 SW FKL 15 WSW HZY 20 WNW HZY 10 WSW ERI
25 WSW DKK 15 NNE DKK 10 S IAG CYSN 35 NE BUF 15 NE ROC 20 N FZY
10 N ART 25 NE GTB 40 SSW SLK 15 WSW GFL 15 SW SCH 25 NE MSV
15 ESE MSV 20 S MSV 35 W MSV 35 SSW BGM 35 WNW IPT FIG
15 SSW DUJ.

MARGINAL RISK OF RAINFALL EXCEEDING FFG TO THE RIGHT OF A LINE FROM
40 SW CDS 35 SE AMA 15 ESE GAG 20 W PPF 25 SE TBN POF
15 WSW JBR 45 WNW DEQ 15 WSW SPS 40 SW CDS.

SLIGHT RISK OF RAINFALL EXCEEDING FFG TO THE RIGHT OF A LINE FROM
25 NE CSM 10 SE END 20 S CFV 25 SSE SGF BPK 35 NNE RUE
20 SE RKR ADM 10 WNW FSI 25 NE CSM.


21/01 UTC UPDATE...

SOME EXPANSION (BROADENING) OF BOTH THE MARGINAL AND SLIGHT RISK
AREAS ALONG AND NORTH OF THE RED RIVER INTO MUCH OF OK  WAS
NECESSITATED BY THE LATEST OBSERVATIONAL AND HRRR/EXPERIMENTAL
HRRR TRENDS. ELEVATED CONVECTION NORTH OF THE STATIONARY BOUNDARY
WILL STEADILY INCREASE IN COVERAGE AND INTENSITY OVERNIGHT AS THE
DYNAMICAL FORCING RAMPS UP AHEAD OF THE APPROACHING TROUGH AND AS
THE RIGHT ENTRANCE REGION OF THE UPPER JET STREAK TRAVERSES THE
AREA. AS THE LOW-LEVEL INFLOW INCREASES AND VEERS OVERNIGHT...THE
POTENTIAL FOR BACK-BUILDING AND TRAINING WILL ALSO RISE...WHICH
GIVEN THE ANTECEDENT THERMODYNAMIC ENVIRONMENT (MUCAPES OF
1000-2000 J/KG AND PWS ~1.25 INCHES)...WOULD POTENTIALLY LEAD TO
LOCALIZED AMOUNTS IN THE 2-4" RANGE WITHIN A 3 OR SO HOUR PERIOD
AS ADVERTISED BY THE MAJORITY OF HIGH-RES CAMS (INCLUDING THE MOST
RECENT HRRR/EXPERIMENTAL HRRR RUNS).

FOR FURTHER DETAILS REGARDING ANY ACTIVE MESOSCALE PRECIPITATION
DISCUSSIONS (MPD) WITHIN THE EXCESSIVE RAINFALL OUTLOOK
AREA...PLEASE REFER TO THE LINK ON THE WPC HOME PAGE OR GO
DIRECTLY TO WWW.WPC.NCEP.NOAA.GOV/METWATCH/METWATCH_MPD.PHP.

HURLEY

...CENTRAL-EASTERN OKLAHOMA EASTWARD INTO SOUTHERN MISSOURI AND
NORTHERN ARKANSAS...

THE INITIAL SHORTWAVE PROGRESSING SLOWLY ENE ACROSS THE UPPER MS
VALLEY TODAY...ALONG WITH THE PRE-FRONTAL CONVECTION AND ATTENDANT
OUTFLOW BOUNDARIES...WILL ALLOW THE SURFACE FRONT TO DROP INTO
SOUTHERN OK-CENTRAL AR BY LATE IN THE DAY. THIS BOUNDARY WILL BE
THE FOCUS FOR POTENTIALLY HEAVY RAINFALL FROM DURING DAY 1...AS A
VIGOROUS NW-SE ORIENTED UPPER LEVEL JET STREAK DROPS INTO THE 4
CORNERS REGION AND AMPLIFIES THE UPPER TROUGH OVER THE
CENTRAL-SOUTHERN ROCKIES. THE DEVELOPING LEE-SIDE LOW AND
DOWNSTREAM UPPER DIFLUENCE...ALONG WITH CONTINUED FORCING WITHIN
THE RIGHT-ENTRANCE REGION OF THE UPPER JET STREAK DRAPED OVER THE
CENTRAL PLAINS...WILL MAKE FOR A DYNAMICALLY-FAVORED ENVIRONMENT
(STRENGTHENING UPPER DIVERGENCE AND LOWER LEVEL FGEN ALONG THE
STATIONARY BOUNDARY) ACROSS CENTRAL-EASTERN OK E-ENE INTO SOUTHERN
MO AND NORTHERN AR. MEANWHILE... A POOL OF ANOMALOUS MOISTURE (PW
AND 850-700 MB MOISTURE FLUX STANDARDIZED ANOMALIES AROUND +2 PER
THE SREF AND GEFS) ADVECTING ACROSS THE STATIONARY
BOUNDARY...ALONG WITH MODEST DEEP-LAYER INSTABILITY (MUCAPES
1000-1500 J/KG)...WILL PROVIDE A FAVORABLE THERMODYNAMIC
ENVIRONMENT FOR AREAS OF HEAVY RAINFALL ACROSS THE
REGION...PARTICULARLY OVERNIGHT. FURTHERMORE... WHILE NOT OVERLY
ROBUST...THE STRENGTHENING LOW-LEVEL WSW FLOW AHEAD OF THE FRONT
WILL BECOME MORE PARALLEL AND CLOSE TO THE MAGNITUDE OF THE MEAN
850-300 MB FLOW BETWEEN 00-12Z...ENHANCING THE POTENTIAL FOR
UPWIND PROPAGATION AND THUS CELL TRAINING.

AS A RESULT...WPC WILL CONTINUE TO CARRY A "SLIGHT" RISK OF
EXCESSIVE RAINFALL INHERITED FROM THE PREVIOUS DAY 2 OUTLOOK...
THOUGH BASED ON THE LATEST GUIDANCE TRENDS (PARTICULARLY WITH THE
ENSEMBLE OF HIGH-RES WINDOWS)...HAVE SHIFTED THE OUTLOOK SLIGHTLY
ENE. IN TERMS OF THE QPF...WPC UTILIZED A MULTI-MODEL BLEND...LED
BY THE HIGH-RES MEANS ALONG WITH THE WPC BIAS-CORRECTED ENSEMBLE
MEAN...WHICH YIELDED A STRIP OF 1-1.5" AREAL-AVERAGE TOTALS ACROSS
THIS AREA. BASED ON THE AFOREMENTIONED FAVORABLE DYNAMICAL AND
THERMODYNAMICAL PARAMETERS...SOME OF THE HIGHER LOCALIZED AMOUNTS
(2-3+ INCHES) ARE REFLECTED ACCORDINGLY IN THE HIGH-RES CAMS. ALSO
HELPING TO DELINEATE THE SLIGHT RISK AREA INCLUDED THE RELATIVELY
LOWER FFG VALUES PER THE RFCS AND HIGHER SOIL SATURATION VALUES
PER THE NATIONAL WATER MODEL...BOTH OF WHICH WOULD BE MORE
CONDUCIVE TO LOCALIZED RUNOFF ISSUES.


...NEW YORK-PENNSYLVANIA...

THE AFOREMENTIONED COMPACT NORTHERN STREAM SHORTWAVE TRAVERSING
THE UPPER MS VALLEY-GREAT LAKES DURING DAY 1 WILL PROVIDE AN
EXTENSIVE SWATH OF MODERATE WAA PCPN WITH EMBEDDED HEAVIER AMOUNTS
WITHIN AREAS OF CONVECTION. PER A MULTI-MODEL BLEND...AN AREA OF
1-1.25" AMOUNTS WAS NOTED ACROSS MUCH OF WESTERN AND UPSTATE
NY...ALONG WITH NORTHWEST PA AND SOUTHEAST LOWER MI. DESPITE THE
ANOMALOUS MOISTURE AVAILABILITY AND VIGOROUS DEEP-LAYER DYNAMICAL
FORCING...INSTABILITY BECOMES MORE LIMITED N-NE OF THE OH VALLEY
(MUCAPES DROP TO UNDER 500 J/KG). THIS WILL IN-TURN MITIGATE
SHORT-TERM RAINFALL RATES...HOWEVER...GIVEN THE LOWER FFG
VALUES/ANTECEDENT WET SOILS OVER THESE AREAS...WILL MAINTAIN A
RELATIVELY SMALL "SLIGHT" RISK FOR EXCESSIVE RAINFALL OVER
PORTIONS OF NY...PARTICULARLY THE CATSKILLS WHERE THE FFG IS
LOWEST...ENCOMPASSED BY A BROADER "MARGINAL" RISK THAT COVERS THE
NORTHERN HALF OF PA AND MUCH OF NY STATE.

HURLEY



...CENTRAL-EASTERN OKLAHOMA EASTWARD INTO SOUTHERN MISSOURI AND
NORTHERN ARKANSAS...

THE INITIAL SHORTWAVE PROGRESSING SLOWLY ENE ACROSS THE UPPER MS
VALLEY TODAY...ALONG WITH THE PRE-FRONTAL CONVECTION AND ATTENDANT
OUTFLOW BOUNDARIES...WILL ALLOW THE SURFACE FRONT TO DROP INTO
SOUTHERN OK-CENTRAL AR BY LATE IN THE DAY. THIS BOUNDARY WILL BE
THE FOCUS FOR POTENTIALLY HEAVY RAINFALL FROM DURING DAY 1...AS A
VIGOROUS NW-SE ORIENTED UPPER LEVEL JET STREAK DROPS INTO THE 4
CORNERS REGION AND AMPLIFIES THE UPPER TROUGH OVER THE
CENTRAL-SOUTHERN ROCKIES. THE DEVELOPING LEE-SIDE LOW AND
DOWNSTREAM UPPER DIFLUENCE...ALONG WITH CONTINUED FORCING WITHIN
THE RIGHT-ENTRANCE REGION OF THE UPPER JET STREAK DRAPED OVER THE
CENTRAL PLAINS...WILL MAKE FOR A DYNAMICALLY-FAVORED ENVIRONMENT
(STRENGTHENING UPPER DIVERGENCE AND LOWER LEVEL FGEN ALONG THE
STATIONARY BOUNDARY) ACROSS CENTRAL-EASTERN OK E-ENE INTO SOUTHERN
MO AND NORTHERN AR. MEANWHILE... A POOL OF ANOMALOUS MOISTURE (PW
AND 850-700 MB MOISTURE FLUX STANDARDIZED ANOMALIES AROUND +2 PER
THE SREF AND GEFS) ADVECTING ACROSS THE STATIONARY
BOUNDARY...ALONG WITH MODEST DEEP-LAYER INSTABILITY (MUCAPES
1000-1500 J/KG)...WILL PROVIDE A FAVORABLE THERMODYNAMIC
ENVIRONMENT FOR AREAS OF HEAVY RAINFALL ACROSS THE
REGION...PARTICULARLY OVERNIGHT. FURTHERMORE... WHILE NOT OVERLY
ROBUST...THE STRENGTHENING LOW-LEVEL WSW FLOW AHEAD OF THE FRONT
WILL BECOME MORE PARALLEL AND CLOSE TO THE MAGNITUDE OF THE MEAN
850-300 MB FLOW BETWEEN 00-12Z...ENHANCING THE POTENTIAL FOR
UPWIND PROPAGATION AND THUS CELL TRAINING.

AS A RESULT...WPC WILL CONTINUE TO CARRY A "SLIGHT" RISK OF
EXCESSIVE RAINFALL INHERITED FROM THE PREVIOUS DAY 2 OUTLOOK...
THOUGH BASED ON THE LATEST GUIDANCE TRENDS (PARTICULARLY WITH THE
ENSEMBLE OF HIGH-RES WINDOWS)...HAVE SHIFTED THE OUTLOOK SLIGHTLY
ENE. IN TERMS OF THE QPF...WPC UTILIZED A MULTI-MODEL BLEND...LED
BY THE HIGH-RES MEANS ALONG WITH THE WPC BIAS-CORRECTED ENSEMBLE
MEAN...WHICH YIELDED A STRIP OF 1-1.5" AREAL-AVERAGE TOTALS ACROSS
THIS AREA. BASED ON THE AFOREMENTIONED FAVORABLE DYNAMICAL AND
THERMODYNAMICAL PARAMETERS...SOME OF THE HIGHER LOCALIZED AMOUNTS
(2-3+ INCHES) ARE REFLECTED ACCORDINGLY IN THE HIGH-RES CAMS. ALSO
HELPING TO DELINEATE THE SLIGHT RISK AREA INCLUDED THE RELATIVELY
LOWER FFG VALUES PER THE RFCS AND HIGHER SOIL SATURATION VALUES
PER THE NATIONAL WATER MODEL...BOTH OF WHICH WOULD BE MORE
CONDUCIVE TO LOCALIZED RUNOFF ISSUES.


...NEW YORK-PENNSYLVANIA...

THE AFOREMENTIONED COMPACT NORTHERN STREAM SHORTWAVE TRAVERSING
THE UPPER MS VALLEY-GREAT LAKES DURING DAY 1 WILL PROVIDE AN
EXTENSIVE SWATH OF MODERATE WAA PCPN WITH EMBEDDED HEAVIER AMOUNTS
WITHIN AREAS OF CONVECTION. PER A MULTI-MODEL BLEND...AN AREA OF
1-1.25" AMOUNTS WAS NOTED ACROSS MUCH OF WESTERN AND UPSTATE
NY...ALONG WITH NORTHWEST PA AND SOUTHEAST LOWER MI. DESPITE THE
ANOMALOUS MOISTURE AVAILABILITY AND VIGOROUS DEEP-LAYER DYNAMICAL
FORCING...INSTABILITY BECOMES MORE LIMITED N-NE OF THE OH VALLEY
(MUCAPES DROP TO UNDER 500 J/KG). THIS WILL IN-TURN MITIGATE
SHORT-TERM RAINFALL RATES...HOWEVER...GIVEN THE LOWER FFG
VALUES/ANTECEDENT WET SOILS OVER THESE AREAS...WILL MAINTAIN A
RELATIVELY SMALL "SLIGHT" RISK FOR EXCESSIVE RAINFALL OVER
PORTIONS OF NY...PARTICULARLY THE CATSKILLS WHERE THE FFG IS
LOWEST...ENCOMPASSED BY A BROADER "MARGINAL" RISK THAT COVERS THE
NORTHERN HALF OF PA AND MUCH OF NY STATE.

HURLEY
$$





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