Quantitative Precipitation Forecast
Issued by NWS

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FOUS30 KWBC 280100
QPFERD

EXCESSIVE RAINFALL DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
859 PM EDT MON JUL 27 2015

...VALID 01Z TUE JUL 28 2015 - 12Z TUE JUL 28 2015...
...REFERENCE AWIPS GRAPHIC UNDER...DAY 1 EXCESSIVE RAINFALL...


SLIGHT RISK OF RAINFALL EXCEEDING FFG TO THE RIGHT OF A LINE FROM
15 SSE K20U 50 ESE BIL 45 ENE LWT 40 ENE GFA 25 ESE CWOE
25 S CWWF CXMD 10 NNE GFK 10 N JMS 20 S KHZE 15 SSE K20U.

SLIGHT RISK OF RAINFALL EXCEEDING FFG TO THE RIGHT OF A LINE FROM
45 W APF 30 SW SRQ 25 WSW SPG 10 W PIE TPA 10 SE MCF 25 NNW PGD
20 E PGD 15 E RSW 20 E APF 25 SSE APF 40 S APF 35 WSW APF
45 W APF.

SLIGHT RISK OF RAINFALL EXCEEDING FFG TO THE RIGHT OF A LINE FROM
30 SSE IRK 20 WNW DSM 15 W FET 15 NNW ONL 35 NE PIR 25 SW K2D5
10 NNW AXN OWA 10 ENE GBG ALN 35 ENE VIH 30 SSE IRK.



...SOUTHWEST TO WEST CENTRAL FLORIDA...

A SLIGHT RISK AREA WAS CONTINUED ALONG COASTAL SECTIONS OF
SOUTHWEST TO WEST CENTRAL FLORIDA.  NO SIGNIFICANT CHANGES
EXPECTED TO THE ELONGATED VORT AXIS STRETCHING FROM THE EASTERN
GULF OF MEXICO ACROSS FLORIDA.  A WEAK LOW LEVEL H85 CENTER OFF
THE SOUTHWEST TO WEST COAST OF FLORIDA---HOWEVER--- IS FORECAST TO
DRIFT SLOWLY NORTHWARD THIS PERIOD.  MOIST ONSHORE WEST SOUTHWEST
FLOW TO THE SOUTH OF THIS WEAK CENTER WILL AGAIN FOCUS HEAVY
RAINFALL POTENTIAL ACROSS SOUTHWEST TO WEST CENTRAL PORTIONS OF
FLORIDA.  SIMILAR TO THE PREVIOUS DAYS---ISOLATED VERY HEAVY
RAINFALL TOTALS OF 5"+ POSSIBLE---CONTINUING THE POTENTIAL FOR
ISOLATED RUNOFF ISSUES--ESPECIALLY IN URBANIZED AREAS.


...PORTIONS OF THE NORTHERN PLAINS SOUTHEAST TOWARD THE MID
MISSISSIPPI VALLEY...

MODELS ARE IN GOOD AGREEMENT WITH THE AMPLIFICATION OF THE UPPER
TROF MOVING FROM THE NORTHERN GREAT BASIN--ACROSS THE NORTHERN
ROCKIES AND INTO THE NORTHERN PLAINS MONDAY INTO EARLY TUESDAY.
WIDESPREAD HEAVY PRECIPITATION TOTALS POSSIBLE IN A DEVELOPING
COMMA HEAD DEFORMATION PRECIPITATION AREA IN A REGION OF
STRENGTHENING UPPER DIFFLUENCE AND ABOVE AVERAGE PW VALUES FROM
PORTIONS OF THE NORTHERN ROCKIES INTO THE NORTHERN HIGH PLAINS.
THERE IS A STRONG MODEL SIGNAL FOR HEAVY PRECIPITATION TOTALS IN
THIS COMMA HEAD--WITH ISOLATED RUNOFF ISSUES POSSIBLE ACROSS
NORTHEASTERN PORTIONS OF MT.

FARTHER TO THE EAST---FRONTAL/PRE-FRONTAL CONVECTION LIKELY TO
ENHANCE MONDAY AFTERNOON INTO MONDAY NIGHT ACROSS PORTIONS OF THE
NORTHERN PLAINS IN A REGION OF VERY STRONG FRONTAL CONVERGENCE.  A
WELL DEFINED CONVECTIVE LINE POSSIBLE TO PUSH EASTWARD MONDAY
NIGHT INTO EARLY TUE THROUGH THE NORTHERN PLAINS AND TOWARD THE
UPPER MS VALLEY.  THIS WILL ALSO SUPPORT ISOLATED RUNOFF ISSUES
SPREADING EASTWARD INTO NORTHERN TO EASTERN ND AND INTO WESTERN
MN.  THIS CONVECTIVE LINE---HOWEVER--- MAY BECOME VERY PROGRESSIVE
MONDAY NIGHT/EARLY TUESDAY---A POSSIBLE LIMITING FACTOR FOR VERY
HEAVY RAIN TOTALS OVER EASTERN PORTIONS OF THE NORTHERN PLAINS
INTO THE UPPER MS VALLEY.  AT THE MOMENT---BEST CHANCES FOR RUNOFF
ISSUES WITH THIS CONVECTIVE LINE MAY BE LATE AFTERNOON INTO EARLY
EVENING BEFORE THE INCREASED CHANCES OF EASTWARD ACCELERATION.


...MID ATLANTIC...

LATE DAY CONVECTION ORIGINATING OVER THE TOPOGRAPHY IN EASTERN
WEST VA HAS EXPANDED E-SE INTO THE MID ATLANTIC REGION WITH THE NW
FLOW ALOFT (0-6 KM NW BULK SHEAR OF 25-30 KTS PER THE LATEST RAP
ANALYSIS). MODEST DEEP LAYER INSTABILITY (MIXED LAYER CAPES ~2000
J/KG) ALONG WITH PWS OF 1.75-2.00 INCHES WILL ALLOW FOR RAINFALL
RATES OF 2-2.25" PER HOUR...WHICH GIVEN THE ADDITIONAL ACTIVITY
UPSTREAM CLOSER TO THE FRONT...MAY ULTIMATELY LEAD TO LOCALIZED
RUNOFF ISSUES LATE THIS AFTERNOON INTO EARLY EVENING. FOR FURTHER
DETAILS...PLEASE REFER TO THE LATEST MESOSCALE PRECIPITATION
DISCUSSION OR FFGMPD #393.

ORAVEC/SULLIVAN/HURLEY
$$





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