Quantitative Precipitation Forecast
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FOUS30 KWBC 270724
QPFERD

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

...VALID 12Z 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 45 W SVC 15 E SOW 55 SSW ABQ 30 ENE SRR 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
55 WSW KEY 50 W KEY 50 NNW MTH 10 N PBI 35 E BCT 60 ESE FLL.

MARGINAL RISK OF RAINFALL EXCEEDING FFG TO THE RIGHT OF A LINE FROM
15 W KMZG 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
20 N DVT 65 WNW LUF 40 N BLH 60 WNW EED 15 NW VGT 30 WNW CDC
50 WNW 4HV 60 W PGA 20 WNW FLG 20 N DVT.

MARGINAL RISK OF RAINFALL EXCEEDING FFG TO THE RIGHT OF A LINE FROM
10 SSW CWGD 25 NNE CWAJ 35 SE TDZ 30 W DAY 15 SSE OLY 10 SW SUS
25 WSW UIN UES 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 SSW FWA 20 SE DNV 10 SE AAA 15 ENE GYY 15 SE GRR MTC DFI
10 SSW FWA.


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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