Quantitative Precipitation Forecast
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FOUS30 KWBC 271409
QPFERD

EXCESSIVE RAINFALL DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1008 AM EDT SAT AUG 27 2016

...VALID 15Z SAT AUG 27 2016 - 12Z SUN AUG 28 2016...
...REFERENCE AWIPS GRAPHIC UNDER...DAY 1 EXCESSIVE RAINFALL...


MARGINAL RISK OF RAINFALL EXCEEDING FFG TO THE RIGHT OF A LINE FROM
60 SSE DUG 50 ENE DUG 50 NE DUG 25 N SAD 10 E IWA 20 W LUF
40 W LUF 30 NNE BLH 45 WSW EED 60 NNE NXP 25 SSW HND 40 ESE LSV
45 S SGU 25 NNW BCE 50 NE PGA 30 N RQE 25 ESE 4SL 30 NW ROW
25 SW ATS 20 NNW GDP 55 ESE MMCS 105 SSE MMCS.

MARGINAL RISK OF RAINFALL EXCEEDING FFG TO THE RIGHT OF A LINE FROM
40 WSW SRQ SPG 10 NE PGD 15 NNE FMY 35 ESE APF 25 WNW TMB
15 WSW FXE BCT 75 ESE MIA 85 ENE MUVR.

MARGINAL RISK OF RAINFALL EXCEEDING FFG TO THE RIGHT OF A LINE FROM
25 SSE KBBF 15 SE KMZG 20 WNW KMZG PKV 25 ENE VCT 25 WSW LFK
10 WSW ACP 15 NNE HSA 15 NNE KVOA 30 ESE KVOA.

MARGINAL RISK OF RAINFALL EXCEEDING FFG TO THE RIGHT OF A LINE FROM
10 SSW CWGD 25 NNE CWAJ 35 SE TDZ 25 WNW DAY 35 SSW BAK EVV
15 SW FOA 10 NNE DEC 10 NE LOT LDM ACB 15 NNW PZQ 10 SSW CWNL.

SLIGHT RISK OF RAINFALL EXCEEDING FFG TO THE RIGHT OF A LINE FROM
20 E KGVX 10 ESE LBX HOU 35 WNW BPT 20 ESE CWF LFT 25 W MSY
25 ESE NEW 10 W KMIS 30 S KMIS.

SLIGHT RISK OF RAINFALL EXCEEDING FFG TO THE RIGHT OF A LINE FROM
10 NE DFI MIE 15 NW BAK 15 ENE BMG 20 NNW BMG 30 NE HUF
30 N LAF LWA 15 SE GRR MTC 10 NE DFI.

SLIGHT RISK OF RAINFALL EXCEEDING FFG TO THE RIGHT OF A LINE FROM
45 SW 40G 20 W 40G 30 NNW GCN 35 S BCE 20 NNW PGA 40 SSE PGA
70 N INW 30 NE INW 15 E SJN 30 S SJN 30 SE SOW 45 NE FFZ
40 NNW LUF 50 ESE EED 20 E EED 15 E IFP 30 ESE IGM 45 SW 40G.


15Z UPDATE...
ADJUSTMENTS WERE MADE WITH SLIGHT/MARGINAL AREAS ACRS THE
MIDWEST/GT LAKES TRIMMING WRN PORTION OF PREVIOUS OUTLOOK AREA
WERE HEAVIER RAIN THREAT CONTINUES TO DIMINISH WITH WEAKENING UPR
FORCING/LOW LEVEL MSTR FLUX.

ACRS THE SOUTHWEST...HAVE EXPANDED MARGINAL RISK AREA EWD WHILE
INCLUDING A SLIGHT RISK AREA IN RESPONSE TO  ONGOING ORGANIZED
CONVECTION ACRS AZ IN ADVANCE OF STG S/WV NEAR THE AZ/CA BORDER.
THIS FEATURE HAS COME IN SLIGHTLY STGR THAN DEPICTED BY THE 00Z EC
BASED ON UA DATA AND THE EXPECTED SLOW MOVEMENT OF THE UPPER VORT
TO THE EAST COULD CONTINUE TO SUPPORT STG STORMS ACRS THE SW
TODAY.  SOUNDING FROM FGZ THIS MRNG INDICATED A FAIRLY MOIST
PROFILE WITH EARLY MORNING LI`S OF -5 AND NEAR 1000 J/KG OF
MUCAPES WHILE PW VALUES JUST SOUTH TOWARD PHX ARE OVER 1.25 J/KG.
WHILE MOST OF THE STORMS HAVE BEEN FAIRLY PROGRESSIVE...SOME HAVE
CONTAINED SOME HIGH SHORT TERM RAIN RATES AND THUS LOCALIZED
EXCESSIVE RAINS WILL BE PSBL.

FINALLY..LOW LEVEL ELY FLOW PATRN WOULD APPEAR TO ONCE AGAIN FAVOR
THE SW COAST OF FLORIDA FOR ENHANCED SEA BREEZE CONVERGENCE IN
VERY MOIST/HIGH CAPE ENVIRONMENT..SO EXPANDED SLIGHT RISK FROM SE
FL COAST TOWARD THE WCNTL/SW COASTS.   SULLIVAN



UPPER TX COAST, SOUTHERN LA, & SOUTHERNMOST MS
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
AN AXIS OF ABOVE NORMAL MOISTURE EXTENDS INTO THE NORTHWEST GULF
COAST ALONG THE SOUTHERN PERIPHERY OF SUBTROPICAL RIDGE, IN THE
VICINITY OF A NEARBY DISTURBANCE.  WHILE THERE ARE DETAIL
DIFFERENCES IN BOTH QPF AMOUNTS AND PLACEMENT, THE GUIDANCE SHOWS
GENERAL AGREEMENT IN KEEPING HEAVIER RAIN AXIS NEAR THE IMMEDIATE
LA/UPPER TX COAST GIVEN WEDGE OF MID/UPR LEVEL DRY AIR JUST TO THE
NORTH ASSOCIATED WITH THE SUBTROPICAL RIDGE AND THE DEGREE OF
ONSHORE FLOW, WHICH SHOULD ALLOW CONVECTION TO FOCUS CLOSE TO THE
COAST PRIMARILY IN THE 06Z-15Z TIME FRAME.  WITH MESOSCALE
GUIDANCE SHOWING POCKETS OF 4-7" AMOUNTS POSSIBLE, A SLIGHT RISK
OF EXCESSIVE RAINFALL IS LIKELY FOR SOUTHERN LA AND THE UPPER TX
COAST, WHICH WAS COORDINATED WITH THE LAKE CHARLES LA AND
HOUSTON/GALVESTON FORECAST OFFICES.


MIDWEST/GREAT LAKES
~~~~~~~~~~~~~~~~~~~
A WEAK SHORTWAVE WILL ESCORT ORGANIZED SHOWERS AND THUNDERSTORMS
NEAR A WEAK LOW PRESSURE AREA THROUGH THE REGION.  THE GUIDANCE,
MESOSCALE AND OTHERWISE, IS HAVING A ROUGH TIME DEPICTING THE
ONGOING CONVECTION IN IL, SO BELIEVE THEIR AMOUNTS ARE TOO LIGHT
IN THIS AREA.  THUNDERSTORMS SHOULD BE EFFICIENT WITHIN A MOIST
AIRMASS WITH SLIGHTLY CONVERGENT LOW-LEVEL INFLOW, WITH HOURLY
RAIN RATES UP TO 2.5".  BELIEVE THE MESOSCALE GUIDANCE,
PARTICULARLY THE 00Z WRF NSSL, 00Z SPC WRF, AND 00Z NAM CONEST
HAVE THE BEST IDEAS CONCERNING THE CONVECTIVE PATTERN IN IL, IN,
AND SOUTHERN MI IN THAT THESE AREAS HAVE A BETTER CHANCE AT HEAVY
RAINFALL THAN PLACES FARTHER NORTHWEST ACROSS WI AND CENTRAL MI
(NORTHERN LP AND EASTERN UP) WHERE INSTABILITY IS MINIMAL.  ADDED
A SLIGHT RISK AREA BASED ON THE 06Z QPF AND THE MESOSCALE SIGNAL
FROM THE PREFERRED GUIDANCE FOR 3-6" IN THIS REGION.


SOUTHWEST
~~~~~~~~~
AN UPTICK IN CONVECTION IS UNDERWAY ACROSS THE SOUTHWEST AND
SOUTHERN ROCKIES IN RESPONSE TO THE SLOW EASTWARD PROGRESSION OF
MID TO UPPER LEVEL TROUGH ACROSS THE AREA.  RECENT RADAR IMAGERY
REVEALS MOISTURE HAS BEEN DRAWN WEST INTO WESTERN AZ/SOUTHERN NV
AND SOUTHEAST CA, WHICH COULD LEAD TO AN EARLIER THAN USUAL
DIURNAL UPSWING OF CONVECTION, OR SIMPLY A MINIMAL BREAK
MID-MORNING.  POTENTIAL EXISTS FOR SOME ISOLATED HEAVY RAINS PER
THE HIGH RESOLUTION GUIDANCE ON THE ORDER OF 2-3", WHICH COULD
FALL IN AN HOUR OR TWO.  A MARGINAL RISK OF EXCESSIVE RAINFALL
EXISTS HERE.

ROTH
$$





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