Quantitative Precipitation Forecast
Issued by NWS

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000
FOUS30 KWBC 290651
QPFERD

EXCESSIVE RAINFALL DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
250 AM EDT MON SEP 29 2014

...VALID 06Z MON SEP 29 2014 - 12Z TUE SEP 30 2014...
...REFERENCE AWIPS GRAPHIC UNDER...DAY 1 EXCESSIVE RAINFALL...



...CENTRAL/PART OF THE NORTHERN HIGH PLAINS...

THE RATHER STRONG/DEEP CLOSED H5 LOW NOW OVER THE CENTRAL GREAT
BASIN IS FORECAST SIMILARLY BY ALL OF THE MODEL GUIDANCE TO LIFT
OUT AND OPEN UP INTO A NEGATIVE TILT H5 TROF THAT REACHES INTO THE
CENTRAL AND NORTHERN HIGH PLAINS BY THE END OF THE PERIOD.  THIS
MORE PROGRESSIVE/LIFTING OUT PROCESS WILL BE ACCOMPLISHED BY THE
STRONG S/WV WHICH IS NOW DROPPING INTO THE BACKSIDE OF THE CLOSED
LOW OVER CENTRAL CA..WITH THIS S/WV ROTATING INTO THE
CENTRAL/SOUTHERN ROCKIES BY MONDAY EVENING AND THEN LIFTING MORE
NORTHWARD THRU THE CENTRAL PLAINS AND INTO PARTS OF THE NORTHERN
PLAINS IN NEGATIVE TILT FASHION MONDAY NIGHT.  AHEAD OF THIS
STRONG NEGATIVE TILT S/WV..THE SOUTHEASTERLY LOW LEVEL JET WILL
REALLY STRENGTHEN INTO THE CENTRAL AND NORTHERN HIGH PLAINS MONDAY
NIGHT BRINGING IN HIGHER PWS FROM THE SOUTHEAST..WHILE LARGE SCALE
LIFT WILL REALLY BE ENHANCED OVER THE SAME REGION UNDER AN
INCREASINGLY FAVORABLE UPPER DIFFLUENT PATTERN.  THIS INCREASE IN
MOISTURE/STRENGTHENING LARGE SCALE LIFT REGIME WILL LEAD TO A
SUBSEQUENT INCREASE IN RAINS ON MONDAY NIGHT FROM THE CO
FOOTLHILLS NORTHWARD THRU THE CENTRAL AND NORTHERN HIGH
PLAINS..WITH AN AXIS OF HEAVY RAINS LIKELY AND EVEN MORE ENHANCED
RAINS LIKELY VICINITY OF THE BLACK HILLS WHERE LOW LEVEL UPSLOPE
FLOW COMES INTO PLAY.  FOR THE MOST PART THE MODEL QPFS ARE IN
DECENT AGREEMENT HERE AND STAYED CLOSE TO THEIR SOLUTION.  EXPECT
AT LEAST SOME 1-2 INCH AREAL AVERAGE RAINS FROM WESTERN NE
NORTHWARD THRU WESTERN SD AND INTO SOUTHWESTERN ND AS WELL AS
EASTERN PARTS OF WY AND SOUTHEASTERN MT..WITH SOME ISOLATED 3+
INCH AMOUNTS POSSIBLE..ESPECIALLY VICINITY OF THE BLACK HILLS.
THESE RAINFALL AMOUNTS MAY CAUSE SOME LOCAL RUNOFF PROBLEMS.


...SOUTHERN GA/NORTHERN PENINSULA

BEEN A TOUGH FORECAST HERE PAST COUPLE OF DAYS..WITH SOME OF THE
MODELS CONSISENTLY TRYING TO INCORRECTLY BRING THE HEAVIER RAINS
INLAND FROM THE GULF INTO THE SOUTHEASTERN STATES.  TONIGHTS MODEL
RUNS ARE DOING A BETTER JOB IN NOW KEEPING THE HEAVIER RAINS
CLOSER TO THE GULF COAST AND THRU THE NORTHERN FL PENINSULA..WHICH
SEEMS TO BE THE RIGHT WAY TO GO..GIVEN THE SURFACE FRONT REMAINS
IN THE NORTHERN GULF OF MEXICO AND THE FLOW REGIME CONTINUES TO BE
FLAT.  DO EXPECT SOME NORTHWARD PUSH INLAND TO THE HEAVIER RAINS
1ST HALF OF THIS PERIOD AS THE RATHER WELL DEFINED H5 S/WV NOW
VICINITY OF THE MOUTH OF THE MS RIVER MOVES GENERALLY
EASTWARD..BRINGING A WEAK FRONTAL WAVE WITH IT AND HELPING TO
STRENGTHEN THE SOUTHERLY TO SOUTHWESTERLY LOW LEVEL JET INTO AND
OVER THE BOUNDARY.  AS THE H5 S/WV AND FRONTAL WAVE PASS OFF THE
SOUTHEASTERN COAST MONDAY EVENING..THE SIGNIFICANT RAINS SHOULD
TAPER OFF.  ALTHOUGH THE MODEL QPFS ARE TRENDING IN THE CORRECT
DIRECTION..THAT IS NOT TO SAY THERE AREN`T SOME QPF PROBLEMS..AND
SUCH IS THE CASE WITH THE 00Z GFS AND UKMET HIRES MODELS..WHICH
ARE AGAIN SUFFERING FROM FEEDBACK PROBLEMS AND WERE NOT CONSIDERED
IN THE MANUAL QPF ONCE AGAIN.  WE GENERALLY FOLLOWED THE HIRES
ARW/NMMB5..WHICH HAD REASONABLY GOOD SUPPORT FROM THE GEM REGIONAL
AND EVEN THE NAM.   THE AVAILABILITY OF HIGH PWS..AT OR ABOVE 2.25
INCHES..WILL LIKELY SUPPORT AT LEAST SOME 1-2 INCH AREAL AVERAGE
RAINFALL AMOUNTS PARTS OF SOUTHERN GA INTO NORTHERN FL..WITH
ISOLATED HEAVIER TOTALS POSSIBLE.

TERRY
$$





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