Quantitative Precipitation Forecast
Issued by NWS

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FOUS30 KWBC 221423
QPFERD

EXCESSIVE RAINFALL DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1022 AM EDT FRI AUG 22 2014

...VALID 15Z FRI AUG 22 2014 - 12Z SAT AUG 23 2014...
...REFERENCE AWIPS GRAPHIC UNDER...DAY 1 EXCESSIVE RAINFALL...


SLIGHT RISK OF RAINFALL EXCEEDING FFG TO THE RIGHT OF A LINE FROM
25 ESE CXMN 60 ESE HVR 15 SSW GGW 15 SW OLF 20 SSE OLF 20 S SDY
15 S DIK 20 E HEI 35 ENE IEN CDR 40 SSW CUT 45 NE IKA 65 N GCC
45 SE LVM 25 SSW LVM 35 SW BZN 25 NE DLN 25 NNW DLN 30 WSW BTM
15 WSW 3DU 30 SSE GPI 25 NNW GPI 25 SSW CWRT 10 NNE CWRT
20 ENE CXBR 10 SSE CPRY 25 ESE CXMN.

SLIGHT RISK OF RAINFALL EXCEEDING FFG TO THE RIGHT OF A LINE FROM
20 N MHK 10 WSW FNB 40 SW LWD 15 NW CDJ 30 WSW CDJ 15 NNE MCI
15 WNW FOE 25 SW MHK 20 N MHK.

SLIGHT RISK OF RAINFALL EXCEEDING FFG TO THE RIGHT OF A LINE FROM
10 ESE DEC 15 S AAA 25 NNE IJX 25 SE MQB 10 S GBG 10 E GBG VYS
20 ESE VYS 10 NNE PNT 20 SW IKK 30 SSW IKK 20 NE TIP DNV
15 S DNV 20 WNW PRG 20 NNW MTO 10 ESE DEC.


1400 UTC UPDATE

CHANGES TO THE PREVIOUS EXCESSIVE RAINFALL POTENTIAL OUTLOOK THAT
STRETCHED FROM THE MID MS VALLEY INTO THE MID WEST WERE BASED
HEAVILY ON THE LATEST SATELLITE AND RADAR TRENDS.  THE ELONGATED
AREA OF CONVECTION STRETCHING FROM THE MID MS VALLEY INTO THE MID
WEST IS BEGINNING TO WEAKEN WITH WARMING CLOUD TOPS EVIDENT ON
LATEST SATELLITE LOOPS.  THIS HAS RESULTED IN THE PREVIOUS
ELONGATED SLIGHT RISK AREA TO BE SEPARATED INTO TWO AREAS FOR
ONGOING CONVECTION.  ONE OVER NORTH CENTRAL IL WHERE A SMALL AREA
OF ENHANCING CONVECTION MOVING FROM SOUTHEAST IA WILL PUSH ACROSS
IN THE NEXT SEVERAL HOURS.

THE EASTERN PORTION OF THE PREVIOUS OUTLOOK AREA WAS MAINTAINED
OVER SOUTHERN WV WHERE FFG VALUES ARE RELATIVELY LOW AND
ADDITIONAL SHOWER ACTIVITY POSSIBLE


NORTHEAST KS INTO NORTHWEST MO

A SLIGHT RISK AREA WAS ADDED OVER FAR NORTHEAST KS INTO FAR NW MO
FOR SLOW MOVING/TRAINING/BACK BUILDING CONVECTION THAT HAS
DEVELOPED ACROSS THIS REGION EARLY THIS MORNING.  MOIST WEST
SOUTHWESTERLY FLOW INTO THIS CONVECTION WILL PERSIST INTO THE
REMAINING HOURS OF FRIDAY MORNING---SUPPORTING ADDITIONAL
DEVELOPMENT AND DOWNSTREAM TRAINING.  CONVECTIVE CELL MOTION
VECTORS FROM NAM AND ESPECIALLY THE GFS SHOW THIS POTENTIAL.
CONFIDENCE NOT GREAT WITH RESPECT TO HOW LONG THIS CONVECTION
PERSISTS---BUT IN AREAS OF TRAINING OVER THE NEXT SEVERAL
HOURS---ISOLATED 2"+ PRECIPITATION AMOUNTS POSSIBLE IN AN HOUR.

NORTHEAST CO INTO FAR SW NEBRASKA


A SLIGHT RISK AREA WAS ADDED OVER NORTHEAST CO INTO FAR SOUTHWEST
NEBRASKA WHERE CONVECTION IS ALREADY ENHANCING AND IS LIKELY TO
CONTINUE THROUGH FRIDAY AS SHORTWAVE ENERGY PUSHES NORTHEASTWARD
OUT OF THE SOUTHWESTERN U.S. UPPER TROF.  FAVORABLE UPPER
DIFFLUENCE AHEAD OF THESE VORTS AND IN THE RIGHT ENTRANCE REGION
OF THE UPPER JET FARTHER TO THE NORTHEAST OVER THE CENTRAL AND
NORTHERN PLAINS WILL SUPPORT CONTINUED ORGANIZED CONVECTION AND
HEAVY RAINS IN AN AXIS OF MUCH ABOVE AVERAGE PW VALUES--- 2 TO
2.5+ STANDARD DEVIATIONS ABOVE THE MEAN--FORECAST ACROSS THIS
REGION.

FAR SW ND---WESTERN SD

THE SLIGHT RISK AREA THAT WAS DEPICTED OVER LARGE PORTIONS OF MT
WAS EXTENDED SOUTHEASTWARD INTO FAR SW ND AND WESTERN SD.  THIS
WAS BASED ON MODEL QPF WHICH DID SHOW POTENTIAL FOR HEAVY AMOUNTS
EXTENDING ACROSS THESE AREAS.  WITH FFG RELATIVELY LOW---ISOLATED
RUNOFF ISSUES POSSIBLE.

ORAVEC


PREVIOUS DISCUSSION

THE ACTIVE CONVECTIVE PATTERN LIKELY TO CONTINUE FOR THE BETTER
PART OF TODAY AND THIS EVENING FROM PARTS OF THE OH VALLEY INTO
THE CENTRAL APPALACHIANS AND MID ATLANTIC STATES..VICINITY OF THE
INITIAL QUASI-STATIONARY FRONTAL BOUNDARY THAT WILL FINALLY GET
PUSHED SOUTHWARD THRU THE UPPER OH VALLEY/CENTRAL APPALACHIANS/MID
ATLANTIC REGION LATER IN THE PERIOD AS THE MID/UPPER FLOW BECOMES
MORE NORTH-NORTHWESTERLY.  A RATHER BROAD BUT MODERATELY STRONG
WEST-SOUTHWESTERLY TO WESTERLY LOW LEVEL JET WILL PERSIST INTO
THIS BOUNDARY INTO THE LATER FRIDAY AFTERNOON/EARLY EVENING
HOURS..WITH PWS FORECAST TO INCREASE/POOL TO NEAR OR ABOVE 2.25
INCHES VICINITY OF THIS BOUNDARY.  THIS..COMBINED WITH THE
LIKELIHOOD OF WEAK H5 S/WV ENERGY MOVING THRU THE REGION ON THE
SOUTHERN EDGE OF THE WESTERLIES/TOP SIDE OF THE H5 RIDGE..WILL
SUPPORT THE ORGANIZED CONVECTIVE DEVELOPMENT..WITH CELLS GENERALLY
MOVING EAST-SOUTHEASTWARD AND THE POTENTIAL EXISTING FOR AT LEAST
SOME TEMPORARY TRAINING OF CELLS.  EXPECT AT LEAST SOME 1-2 INCH
AREAL AVERAGE RAINS FROM PARTS OF THE OH VALLEY INTO THE CENTRAL
APPALACHIANS WITH ISOLATED GREATER THAN 3 INCH TOTALS QUITE
POSSIBLE..WHICH COULD CAUSE SOME FLOODING PROBLEMS.


A VERY WET PATTERN WILL BE DEVELOPING OVER MT MAINLY DURING THE
2ND PART OF THIS PERIOD..AS A VERY COOL SEASON-LIKE H5 TROF DIGS
INTO THE AREA.
THIS MID TO UPPER TROF AMPLIFICATION AND A MARKED STRENGTHENING OF
THE VERY MOIST EAST TO EAST-SOUTHEASTERLY LOW LEVEL JET INTO
ESPECIALLY MT WILL LEAD TO THE DEVELOPMENT OF WIDESPREAD
RAINS/CONVECTION THRU MUCH OF MT..WITH SOME HEAVY TO VERY HEAVY
AMOUNTS LIKELY IN THE UPSLOPE AREAS BACK IN CENTRAL MT.  MODEL
QPFS HERE ARE IN VERY GOOD AGREEMENT WITH HEAVY TOTALS..AND STAYED
CLOSE TO THEIR SOLUTIONS..WITH AT LEAST SOME 1-2+ INCH AREAL
AMOUNTS LIKELY IN CENTRAL MT AND ISOLATED HEAVIER TOTALS OF 3+
INCHES POSSIBLE..BUT WITH WIDESPREAD MODERATE TO LOCALLY HEAVY
RAINS THRU MUCH OF MT.


...PORTIONS OF THE CENTRAL/NORTHERN PLAINS...

THIS WILL BE ANOTHER INCREASINGLY WET PORTION OF THE NATION
BEGINNING LATER FRIDAY AFTERNOON AND NIGHT..AS THE H5 TROF DIGS
INTO THE WESTERN STATES..ALLOWING A SOUTHERLY LOW LEVEL JET TO
STRENGTHEN AND OVERRUN A SURFACE BOUNDARY IN PLACE FROM PARTS OF
IA WESTWARD INTO NE AND SD.  EVEN FARTHER NORTH OF THE SURFACE
BOUNDARY..A STRENGTHENING EAST TO EAST-SOUTHEASTERLY AND VERY
MOIST LOW LEVEL JET WILL LEAD TO INCREASINGLY FAVORABLE UPSLOPE
CONDITIONS IN THE HIGH PLAINS..SUPPORTING ENHANCED RAINS OVER
ESPECIALLY WESTERN NE AND WESTERN SD.  A MAJORITY OF THE MODEL
QPFS WERE QUITE WET HERE..AND FOLLOWED THEM CLOSELY..WITH AT LEAST
SOME 1-2 INCH AREAL AVERAGE RAINS EXPECTED AND SOME ISOLATED
HEAVIER TOTALS POSSIBLE.

TERRY
$$





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