Quantitative Precipitation Forecast
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764
FOUS30 KWBC 290059
QPFERD

EXCESSIVE RAINFALL DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
859 PM EDT TUE MAR 28 2017

...VALID 01Z WED MAR 29 2017 - 12Z WED MAR 29 2017...
...REFERENCE AWIPS GRAPHIC UNDER...DAY 1 EXCESSIVE RAINFALL...


MARGINAL RISK OF RAINFALL EXCEEDING FFG TO THE RIGHT OF A LINE FROM
50 W CNK 20 NNE MHK 30 ENE UKL 20 SW GMJ 20 SE DUA 20 SW GDJ
20 SW E29 50 NNE 6R6 30 SE MAF 30 NNW BPG 15 W LBB 25 NE CVN
40 WSW DHT 15 SSW SPD 55 NNW GCK 50 W CNK.

SLIGHT RISK OF RAINFALL EXCEEDING FFG TO THE RIGHT OF A LINE FROM
20 WNW 1F9 45 WNW RPH 15 WSW LTS 15 NE WWR 35 WNW PTT 30 NE GBD
25 NNE EWK 40 ENE WLD 20 ENE CQB 10 NNW ADM 20 WNW 1F9.


0100 UTC UPDATE

EXPANDED THE MARGINAL RISK AREA FARTHER WEST (INTO WEST TX) TO
ACCOUNT FOR ADDITIONAL CONVECTIVE ELEMENTS DEVELOPING WITHIN A
SECONDARY...NARROWER WARM CONVEYOR BELT (ENHANCED DEEP-LAYER MOIST
PLUME) JUST EAST OF THE MID-UPPER LOW...WHERE THE UPPER DIFFLUENCE
REMAINS QUITE FAVORABLE.


1500 UTC UPDATE

THE ONLY CHANGE MADE TO THE PREVIOUS EXCESSIVE RAINFALL POTENTIAL
OUTLOOK WAS TO EXPAND THE MARGINAL RISK AREA WESTWARD INTO THE TX
PANHANDLE TO COVER THE DEVELOPING CONVECTION ACROSS THIS REGION.
ALL OF THE HI RES GUIDANCE---INCLUDING THE LATEST HRRR---ARE
SLOW---1 TO 2 HOURS---TO DEVELOP THIS ACTIVITY WHEN COMPARING
THEIR SIMULATED RADARS TO CURRENT RADAR.  THIS SEEMS TO BE A
TYPICAL ERROR WITH CONVECTIVE DEVELOPMENT SEEN IN THE HI RES
GUIDANCE.  ONCE CONVECTION DOES FORM IN THE HI RES
GUIDANCE---HOURLY PRECIP RATES OF .50-.75" ARE DEPICTED OVER THE
TX PANHANDLE.  THESE RATES SEEM REASONABLE GIVEN LATEST RADAR
ESTIMATES---ALBEIT THEY ARE OCCURRING 1 TO 2 HOURS EARLIER THAN
MODELS FORECAST.

ORAVEC

...S-CENTRAL PLAINS...

IT REMAINS THE CASE THAT STRONG JET ENERGY DIVING INTO THE
BACKSIDE OF THE FULL-LATITUDE TROUGH NOW MOVING THROUGH THE
INTERMOUNTAIN WEST WILL ALLOW THIS SYSTEM TO AMPLIFY CONSIDERABLY
AS IT REACHES THE ROCKIES...PARTICULARLY ACROSS THE 4 CORNERS AND
SOUTHERN ROCKIES WHERE THE MORE VIGOROUS SOUTHERN STREAM COMPONENT
WILL LEAD TO A DEEPENING CLOSED LOW THAT SUBSEQUENTLY TRACKS
STEADILY INTO THE S-CENTRAL HIGH PLAINS LATER DAY1. THE ENSUING
LEE-SIDE CYCLOGENESIS WILL LEAD TO AN ELONGATED STRIPE OF
MOD-HEAVY PCPN ASSOCIATED WITH THE WARM CONVEYOR BELT AND
EVOLVING/EXPANDING CCB/DEFORMATION AND DEEPENING TROWAL. LEAD
POTENT LLJ MOISTURE INFLOW UP THROUGH THE SRN PLAINS WITH SYSTEM
DEVELOPMENT SUGGESTS CONDITIONS FAVORABLE FOR AN EXCESSIVE
RAINFALL THREAT. CONVECTIVE DEVELOPMENT AND OVERALL TRANSLATION
REMAINS UNCERTAIN AND POTENTIALLY PROGRESSIVE WITH MESO COLD POOL
DEVELOPMENTS...BUT DEEPEST AND MOST ANOMALOUS MOISTURE (PWS UP TO
1.5") AND HEIGHT FALLS/INSTABILITY SEEMS TO COMBINE/FOCUS MOST
OVER S-CENTRAL OK AND NRN TX...ESPECIALLY WITH CELL MERGERS. WPC
PROGS HAVE TRENDED HEAVIEST QPF UPWARDS TO 3-5" LOCALLY
THERE...WITH MORE MODERATE TO HEAVY AMOUNTS WRAPPED UP ACROSS THE
CENTRAL PLAINS. THIS SCENARIO IS MORE SUPPORTED NOW BY WELL
CLUSTERED 00 UTC ARW/NMMB/WRF NSSL/NAM CONEST GUIDANCE AND FITS
WELL WITH THE CURRENT SPC SEVERE THREAT AREAS.

SCHICHTEL
$$





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