Quantitative Precipitation Forecast
Issued by NWS

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FOUS30 KWBC 112006
QPFERD

EXCESSIVE RAINFALL DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
405 PM EDT FRI JUL 11 2014

...VALID 21Z FRI JUL 11 2014 - 00Z SUN JUL 13 2014...
...REFERENCE AWIPS GRAPHIC UNDER...DAY 1 EXCESSIVE RAINFALL...


SLIGHT RISK OF RAINFALL EXCEEDING FFG TO THE RIGHT OF A LINE FROM
25 ENE COS 15 NNE VTP 20 NE ALS 30 ESE MYP 30 ESE LXV 30 NE CCU
35 SSW PUM 10 E ARL 25 N RWL 35 SE BPI 50 NNW RIW 10 SSE DHS
35 NNW CDR 35 WNW VTN 30 E MHE 20 ENE FKA 20 SW RYV 15 E IKK MTO
FFL TQE 15 W LBF 20 N AKO 25 ENE COS.



...SERN WY/NERN CO THROUGH NRN NE TO IA AND NRN IL/SRN WI...

A NARROW AXIS OF HEAVY RAINFALL IS ANTICIPATED OVERNIGHT FRI
THROUGH SAT FROM NERN CO/SERN WY TO PARTS OF THE MID/UPPER MS
VALLEY. A WELL-DEFINED SHORT WAVE TROUGH... VIA WATER VAPOR
IMAGERY... WILL EJECT OUT OF NRN CO/SERN WY AND TRACK QUICKLY
DOWNSTREAM THROUGH THE CENTRAL PLAINS AND MID MS VALLEY. THIS WILL
BE AHEAD OF A VERY STRONG SURFACE COLD FRONT DIGGING SOUTH AND
EAST THROUGH THE UPPER MIDWEST AND ALONG THE NRN EDGE OF A
BUILDING MID TO UPPER RIDGE OVER THE SRN/CENTRAL PLAINS. THE
SQUEEZE PLAY BETWEEN THE DRY AIR BEHIND THE COLD FRONT AND DRY AIR

UNDERNEATH THE RIDGE WILL SETUP A VERY NARROW ZONE OF INSTABILITY
AND MOISTURE POOLING. THE GUIDANCE... ESPECIALLY THE GFS AND
ECMWF... CAPTURE THIS SCENARIO AND DEPICT THE DYNAMIC SHORT WAVE
TRANSITIONING VERY FAST DOWNSTREAM. THE ACTION BEGINS TO DEVELOP
LATE AFTN/EVENING ACROSS SERN WY/NERN CO AS DEVELOPING CONVECTION
POSSIBLY MERGES INTO A CLUSTER AND ADVANCE DOWNSTREAM. THE COMPLEX
WILL THEN PROGRESS ACROSS NRN/CENTRAL NE AND SRN SD WITH SOME
MOISTURE BACKING NWWRD TO THE SURFACE COLD FRONT OVER NWRN SD/SWRN
ND. MEANWHILE... JUST AHEAD OF THE COMPLEX OVERNIGHT... ENOUGH OF
A NOCTURNAL LOW LEVEL SWRLY JET COULD YIELD SOME STORM
ACTIVITY/HEAVY RAIN ACROSS IA INTO NORTH CENTRAL IL. BY
MORNING/MIDDAY SAT INTO THE AFTN HRS... THE SMALL SCALE SYSTEM
WILL MERGE WITH THE WESTERLIES AND FRONT FOR POSSIBLY MORE
WIDESPREAD CONVECTIVE RAINFALL ACROSS IA/WI/MI INTO NRN/CENTRAL
IL/IN... THOUGH THIS LATTER PERIOD HAS A BIT MORE UNCERTAINTY. THE
SHEAR AXIS EXTENDING BACK SOUTH AND WEST FROM THE COMPLEX COULD
ALSO SPIKE AN INCREASE IN DIURNAL CONVECTION AND HEAVY RAINFALL
ACROSS ERN CO... ESPECIALLY IN NERN CO. THE 3HR FFG AVGS FROM 2 TO
3 INCHES ACROSS THE EXTENDED REGION... WHICH IS NOT PARTICULARLY
LOW. HOWEVER WITH SUCH A DISTINGUISHABLE FEATURE ON WATER VAPOR...
MODELS IN AGREEMENT ON THE LIKELY TRACK/PROGRESSION OF THE SMALL
SCALE VORT... DEEP MOISTURE IN PLACE AND POSSIBLE 1 TO 3 INCH
AMOUNTS ANTICIPATED... WPC FELT KEEPING CONSISTENCY WITH A SLIGHT
THREAT AND COMBINED THE TWO AREAS INTO ONE.

...21Z UPDATE FOR PARTS OF EASTERN AZ/WESTERN NEW
MEXICO...CENTRAL/NORTHERN UT AND SOUTHEAST ID...

THE BEST FOCUS FOR ORGANIZED AREAS OF HEAVY TO EXCESSIVE RAINFALL
SHOULD BE IN THE AREA MENTIONED ABOVE AS A MID LEVEL SHORTWAVE
LIFTS NORTHEAST.  BESIDES THE BETTER DYNAMICS...THE MOISTURE IS
DEEPER IN THAT REGION.  HOWEVER...CONVECTION FORMING OVER THE
HIGHER TERRAIN FROM WESTERN NEW MEXICO INTO UT AND SOUTHEAST ID
MAY STILL BE ABLE TO PRODUCE ISOLATED FLASH FLOODING FROM THE
REMAINDER OF THIS AFTERNOON INTO THIS EVENING.  BLENDED TPW
SATELITE IMAGER STILL SHOWS AREAS WHERE PW WERE AOA 1.2 INCHES
FROM NEW MEXICO INTO UT...WITH A PW VALUE APPROACHING 1.5 INCHES
NEAR THE UNITA RANGE.  STORMS SHOULD BE SLOW MOVING...WHICH MEANS
THAT LOCALIZED FLOODING PROBLEMS COULD OCCUR ESPECIALLY IF THE
STORMS SPEND A LOT OF TIME OVER ANY ONE SPOT IN THE COMPLEX
TERRAIN. SEE LITTLE REASON TO ARGUE WITH THE MODELS WHICH SHOW
GRADUAL DECREASE IN COVERAGE AND INTENSITY OF PCPN LATER TONIGHT
AND SATURDAY MORNING AS THE ATM STABILIZES.

MUSHER/BANN

$$




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