Quantitative Precipitation Forecast
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FOUS30 KWBC 291859
QPFERD

EXCESSIVE RAINFALL DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
258 PM EDT FRI MAY 29 2015

...VALID 21Z FRI MAY 29 2015 - 12Z SAT MAY 30 2015...
...REFERENCE AWIPS GRAPHIC UNDER...DAY 1 EXCESSIVE RAINFALL...


SLIGHT RISK OF RAINFALL EXCEEDING FFG TO THE RIGHT OF A LINE FROM
15 S C75 20 SSE IJX ALN 20 ENE FAM 25 SW CGI 10 SW DYR
30 SSW MKL 25 N TUP TUP 20 SSE TUP 35 W GTR 40 ESE GWO
15 SSE GWO 25 WSW GWO 15 WSW GLH 20 WSW GLH 25 S LLQ 35 NNE IER
LFK 40 SSW PSN 20 S 7F9 40 NNW SJT 35 SE BPG 10 SW BPG
45 NNW MDD 40 NE HOB 55 NNE HOB 50 SSE CVN 30 ESE CVN 40 E CVN
35 NNW PVW 30 SSE AMA 40 S PPA 30 W CSM CHK 20 S SNL 20 SW OKM
10 WNW CFV 10 SSW CNU 40 E UKL 35 ENE LXT 25 WNW IRK 35 SW OTM
15 SE PEA TNU 10 W MIW 25 NNW MIW 20 SW AXA 10 NNW SPW
15 SSE PQN 30 WNW MML DXX 10 E BBB 20 N 2P3 25 WNW JMR 20 NE JMR
ARV IMT 20 ENE MCD 25 NW CWNL 10 ESE CYZE 25 NE CXCY CYVV
15 SSE BAX 15 NNE FNT 10 NNE AZO DKB 15 S C75.

MODERATE RISK OF RAINFALL EXCEEDING FFG TO THE RIGHT OF A LINE FROM
55 S F05 40 NW RPH 30 WNW GLE 15 SW 1F0 15 NW GYI 15 E GYI
25 NE TKI 15 E TKI HQZ 15 ESE JWY 15 NNW INJ 15 E SEP SEP
30 NNW 7F9 20 ENE ABI 15 N DYS 35 NNW DYS 55 NNE SWW 65 NE SNK
55 SSW F05 55 S F05.


1800 UTC UPDATE

SOUTHERN PLAINS TOWARD THE LOWER MS VALLEY

CHANGES TO THE PREVIOUS EXCESSIVE RAINFALL POTENTIAL OUTLOOK OVER
THE SOUTHERN PLAINS INCLUDED ADDING A MODERATE RISK AREA OVER
NORTH CENTRAL TX WHICH WAS HIT HARD BY LAST NIGHTS ORGANIZED
CONVECTION.  IN THE WAKE OF THE MCV LIFTING NORTHEASTWARD OVER
CENTRAL TO EASTERN OK THIS AFTERNOON---ADDITIONAL HEIGHT FALLS
EXPECTED TO PUSH EAST SOUTHEASTWARD ACROSS NORTH TO NORTH CENTRAL
TX TONIGHT INTO SATURDAY.  THIS WILL ENHANCE UVVS ALONG AND AHEAD
OF THE SOUTHWARD MOVING COLD FRONT OVER THE SOUTHERN
PLAINS---SUPPORTING POTENTIAL FOR ADDITIONAL ORGANIZED CONVECTION
OVER NORTH AND NORTH CENTRAL TX TONIGHT---INTO SOUTHEAST TX DURING
SATURDAY.  THERE IS A BETTER SIGNAL IN THE LATEST MODEL GUIDANCE
FOR ORGANIZED ACTIVITY THAN WITH LAST NIGHTS CONVECTION.
HOWEVER---THERE ARE STILL DIFFERENCES WITH THE
DETAILS---ESPECIALLY HOW QUICKLY THE CONVECTION PUSHES DOWNSTREAM
AND AT WHAT AXIS THE MAX PRECIP OCCURS.  WITH NOT A HIGH LEVEL OF
CONFIDENCE WITH RESPECT TO THE AXIS---WPC WENT WITH SOMEWHAT OF A
COMPROMISE BETWEEN THE FARTHER NORTH AXES OF THE CMC GEM AND NAM
CONEST AND THE FARTHER SOUTH HI RES ARW AND 1200 UTC ECMWF---BUT
DID TREND FASTER TO MOVE CONVECTION DOWNSTREAM GIVEN THE MODEL
BIAS TO BE TOO SLOW.  THERE MAY BE A PERIOD OF TRAINING OF CELLS
IN A WEST TO EAST DIRECTION ALONG AND SOUTH OF THE FRONT TONIGHT
INTO SATURDAY ACROSS NORTH TO NORTH CENTRAL TX.  WITH RECENT HEAVY
RAINS LOWERING FFG VALUES---ADDITIONAL RUNOFF PROBLEMS
LIKELY---ESPECIALLY IF THE HEAVY RAINS GET BACK INTO THE
DALLAS-FORT WORTH AREA HIT HARD IN LAST NIGHTS ACTIVITY.

FROM THE LOWER MO VALLEY--MID MS VALLEY REGION---THE PREVIOUS
SLIGHT RISK AREA WAS EXPANDED EASTWARD INTO EASTERN MO AND ACROSS
ARKANSAS.  THE MCV FROM LAST NIGHTS SOUTHERN PLAINS CONVECTION
EXPECTED TO TRACK NORTHEASTWARD INTO THE MID MS VALLEY---LOWER MO
AND LOWER OH VALLEY TONIGHT INTO SATURDAY.  HEAVY RAINS POSSIBLE
IN THE COMMA HEAD/DEFORMATION TYPE PRECIP BAND JUST AHEAD OF THE
VORT MOVING OUT OF EASTERN OK INTO SOUTHERN AND CENTRAL MO---AND
WITH THE TRAILING CONVECTIVE TAIL EXPECTED TO PUSH/BUILD EASTWARD
ACROSS AR.  THE NAM WAS PREFERRED WITH THE CONVECTION OVER
ARKANSAS---WHILE THE 1200 UTC ECMWF HAS TRENDED HEAVIER AND CLOSER
TO THE NAM/GFS HEAVY SOLUTION OVER CENTRAL TO SOUTHERN MO AS IT
SEEMS TO HAVE A BETTER HANDLE ON THE MCV.

UPPER MS VALLEY--L.P. OF MI

THE SLIGHT RISK AREA OVER THE UPPER MS VALLEY AHEAD OF THE STRONG
FRONT PRESSING SOUTHWARD WAS EXPANDED EASTWARD INTO THE CENTRAL
AND NORTHERN PORTIONS OF THE L.P. OF MI.  FAVORABLE RIGHT ENTRANCE
REGION UPPER JET DYNAMICS IN AN AXIS OF MUCH ABOVE AVERAGE PW
VALUES--2 TO 2.5+ STANDARD DEVIATIONS ABOVE THE MEAN ALONG AND
AHEAD OF THIS FRONT WILL SUPPORT POTENTIAL FOR ORGANIZED
FRONTAL/PRE-FRONTAL CONVECTION.  WEST SOUTHWESTERLY LOW LEVEL FLOW
ALONG AND AHEAD OF THIS FRONT WILL SUPPORT TRAINING AND/OR BACK
BUILDING OF CONVECTION---WITH LOCALLY VERY HEAVY TO EXCESSIVE
PRECIPITATION TOTALS POSSIBLE IN AREAS OF TRAINING.

NO CHANGES TO THE THINKING OVER THE CENTRAL APPALACHIANS.  LOCALLY
HEAVY RAINS LIKELY THIS AFTERNOON IN THE SCATTERED CONVECTION ON
THE WESTERN EDGE OF THE MID TO UPPER LEVEL HIGH OVER THE MID
ATLANTIC WHERE WEAK SHORTWAVES ARE EMBEDDED IN THE AXIS OF ABOVE
AVERAGE PW VALUES.  WITH FFG VALUES RELATIVELY LOW FROM PORTIONS
OF SW VA INTO WV AND WESTERN PA---CAN NOT RULE OUT ISOLATED RUNOFF
ISSUES LATER TODAY FROM SCATTERED CONVECTION THAT FORMS IN THIS
HIGH PW AXIS WHERE UVVS ARE ENHANCED AHEAD OF THE ABOVE MENTIONED
WEAK VORTS.

ORAVEC


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