Quantitative Precipitation Forecast
Issued by NWS

Home | Current Version | Previous Version | Text Only | Print | Product List | Glossary On
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
000
FOUS30 KWBC 291855
QPFERD

EXCESSIVE RAINFALL DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
254 PM EDT MON AUG 29 2016

...VALID 21Z MON AUG 29 2016 - 12Z TUE AUG 30 2016...
...REFERENCE AWIPS GRAPHIC UNDER...DAY 1 EXCESSIVE RAINFALL...


MARGINAL RISK OF RAINFALL EXCEEDING FFG TO THE RIGHT OF A LINE FROM
85 WSW SPG 50 WSW PIE 15 SSW BKV 15 ESE BOW 10 E MCO 30 SSE AYS
15 SSE TBR 15 S CTZ MQI 100 E HSE.

MARGINAL RISK OF RAINFALL EXCEEDING FFG TO THE RIGHT OF A LINE FROM
50 ESE BRO 35 ESE BRO 10 S PIL 30 SE BKS 15 S SSF 15 NE 6R9
15 SSE INJ 10 ESE OCH POE 20 NNW GAO 15 SSW KMIS 20 NNW CYD.

MARGINAL RISK OF RAINFALL EXCEEDING FFG TO THE RIGHT OF A LINE FROM
10 WNW EKN 25 N W99 15 S CBE 15 WSW OKV 15 NW SHD 15 SSE LWB
10 ENE BKW 10 WNW EKN.

MARGINAL RISK OF RAINFALL EXCEEDING FFG TO THE RIGHT OF A LINE FROM
140 SE DUG 90 SW MMCS 20 ENE TCS 35 S ALS 40 SE MYP 25 ESE CCU
30 WSW BJC 10 NW BJC DEN 25 NW LIC 15 ESE LIC 20 WNW ITR
25 SE IML 20 SW BVN 25 WSW SUX 10 NNE SUX 25 NW ORC 20 NW FSD
20 WSW BKX 20 E ATY 10 E BRD 10 ENE CKC 25 ESE CWEC.

MARGINAL RISK OF RAINFALL EXCEEDING FFG TO THE RIGHT OF A LINE FROM
65 NNW ERY 20 E MBL 30 NNE GYY 20 NE BRL 25 NE LXT 15 SE END
25 ESE CDS 10 SW BPG 50 ENE 6R6 40 WSW DRT 70 WSW DRT.

SLIGHT RISK OF RAINFALL EXCEEDING FFG TO THE RIGHT OF A LINE FROM
40 S APF 15 SSW FMY 10 ESE RSW 40 ESE APF 35 WNW FXE 20 WSW PBI
SUA 15 E SUA 30 ENE PBI.

SLIGHT RISK OF RAINFALL EXCEEDING FFG TO THE RIGHT OF A LINE FROM
15 N KOPM 30 W KMIU 10 N CRP 50 SE SSF 25 NNE 62H 15 W DRI
20 WNW LFT PTN 20 NNW S58.

SLIGHT RISK OF RAINFALL EXCEEDING FFG TO THE RIGHT OF A LINE FROM
25 ESE MMCS 25 W HMN 30 WNW 4CR 25 N CQC 15 W RTN 30 NNE VTP
35 WSW APA 20 SW APA COS 10 NE PUB 30 SE TAD 35 WSW CAO
45 NNW TCC 40 SW TCC 25 W CVS 45 E TCC 20 WSW DUX 15 N DUX
10 NW GUY 35 W HYS 10 E HLC 20 SSW HSI 20 SW OFF 15 SE AIO
10 E CSQ 25 SW LWD 10 ENE STJ 20 WNW FOE 35 WNW EMP 20 NE WWR
40 NNW CDS 35 E PVW 25 SSE LBB 25 SW FST 15 WNW 6R6 75 SSE E38
95 S E38 70 SSW GDP 25 ESE MMCS.


1900 UTC UPDATE

ONLY SOME SMALL CHANGES MADE TO THE 1500 UTC EXCESSIVE RAINFALL
POTENTIAL OUTLOOK.  OVER THE CENTRAL PLAINS---THE SLIGHT RISK AREA
WAS EXTENDED FARTHER NORTHEASTWARD INTO FAR SOUTHEAST NE---FAR NW
MO AND FAR SW IA FOR AREAS OF LOWER FFG VALUES.  THE MARGINAL RISK
AREAS THAT SHOWED A SMALL BREAK OVER NORTHERN IA---FAR SOUTHERN
MN---SOUTHERN WI AND FAR NORTHEAST IL WERE COMBINED GIVEN LOW
CONFIDENCE ON SAYING SUCH A SMALL AREA HAD LESS RISK THAN THOSE
DEPICTED IN THE MARGINAL RISK AREA.

NO CHANGES MADE TO THE RISK AREAS ALONG THE WESTERN GULF COAST OR
ACROSS CENTRAL TO SOUTH FLORIDA AND THE COASTAL SOUTHEAST.


UPPER MS VALLEY INTO THE UPPER LAKES

ADDITIONAL CONVECTION MAY FIRE LATER THIS AFTERNOON INTO MONDAY
NIGHT ALONG AND AHEAD OF THE COLD FRONT FORECAST TO PUSH
SOUTHEASTWARD THROUGH THE UPPER MS VALLEY AND UPPER LAKES REGION.
MODEL CONSENSUS FOLLOWED WITH MODERATE TO LOCALLY HEAVY PRECIP
TOTALS DEPICTED.  A MARGINAL RISK OF RUNOFF ISSUES MAINTAINED FROM
EARLIER FORECASTS.


CENTRAL AND SOUTHERN PLAINS/FRONT RANGE OF THE ROCKIES
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
A WEAKENING NE/SW ORIENTED SHEAR AXIS ALOFT INTERACTING WITH
MOIST/UNSTABLE CONDITIONS EXTENDING FROM THE SOUTHERN HIGH PLAINS
THROUGH THE CENTRAL PLAINS INTO IA WILL LEAD TO WIDESPREAD MAINLY
DIURNAL TSTM ACTIVITY BUT WITH WEAK LOW LEVEL FLOW AND LACK OF STG
LOW LEVEL FOCUS, ACTIVITY ACRS THIS REGION WILL BE HIGHLY
MESOSCALE DRIVEN/POTENTIALLY PULSE.  ANOTHER ACTIVE THUNDERSTORM
DAY IS EXPECTED FROM WESTERN TX AND EASTERN NM INTO KS, WITH SLOW
MOVING CELLS LEADING TO LOCALIZED HEAVIER RAINS, ON THE ORDER OF
2.5" AN HOUR.  THE MESOSCALE GUIDANCE SHOWS LOCAL MAXIMA IN THE
3-5" RANGE WITHIN THIS REGION.  BECAUSE OF LOW FLASH FLOOD
GUIDANCE VALUES CAUSED BY RECENT RAINS, A FAIRLY LARGE SLIGHT RISK
OF EXCESSIVE RAINFALL WAS ADDED FROM WESTERN TX, EASTERN NM, AND
THE FRONT RANGE OF THE CO ROCKIES.


WESTERN GULF COAST
~~~~~~~~~~~~~~~~~~
A WEAK UPPER LOW OVER THE NW GULF ALONG WITH A WEAK SFC REFLECTION
IS EXPECTED TO WEAKEN SLOWLY AND EXPECTED TO DRIFT SLOWLY TOWARD
THE WEST OR SOUTHWEST. AGREE WITH THE MODEL CONSENSUS IN KEEPING
HEAVIER RAINS NEAR AND OFF THE TX/LA COASTS WITH BETTER LOW LEVEL
CONVERGENCE...BUT POCKETS OF HEAVIER DIURNAL TSTMS RAINS WILL
CONTINUE TO DVLP NWD INTO ERN TX/LA WITH DIFFERENTIAL HEATING
WITHIN UNSEASONABLY MOIST AIRMASS.  USED THE NORTHWARD PENETRATION
TO THE ECHOES SEEN ON RADAR THE PAST COUPLE DAYS TO HELP DEPICT
THE NORTHERN EXTENT, WHICH WAS A REASONABLE MATCH TO THE 12Z
ECMWF.  HOURLY RAIN RATES UP TO 3" ARE POSSIBLE WHERE CELLS MERGE
AND/OR TRAIN.  LOCAL AMOUNTS IN THE 3-5" RANGE ARE POSSIBLE PER
THE MESOSCALE GUIDANCE, AND SOME OF THIS REGION RECEIVED LOCALLY
HEAVY RAINFALL OVER THE PAST COUPLE DAYS WHICH HAS LOWERED FLASH
FLOOD GUIDANCE VALUES/SATURATED SOILS.  A SLIGHT RISK OF EXCESSIVE
RAINFALL WAS ADDED FOR WATER LOGGED SOUTHWEST LA AS WELL AS THE
MIDDLE AND UPPER TX COASTS.


FLORIDA
~~~~~~~
INCREASINGLY CONVERGENT LOW-LEVEL FLOW TO THE EAST OF TROPICAL
DEPRESSION #9 TRACKING THROUGH THE FLORIDA STRAITS/NEAR THE CUBAN
COAST WILL DRAW MOIST TROPICAL AIR WITH PRECIPITABLE WATER VALUES
OVER 2.25 INCHES INTO SOUTHERN FL WHICH SHOULD LEAD TO EFFICIENT
RAIN PRODUCING SHOWERS/THUNDERSTORMS, TO THE TUNE OF 3" AN HOUR
WHERE CELLS MERGE AND/OR TRAIN.  THESE SORT OF RAIN RATES WOULD
QUICKLY OVERWHELM THE URBANIZED KEYS AS WELL AS TOWNS/CITIES ALONG
THE SOUTHWEST AND SOUTHEAST FL COASTLINE.  LOCAL AMOUNTS IN THE
5-7" RANGE ARE EXPECTED OVER THE NEXT FEW DAYS.  SEE TROPICAL
CYCLONE ADVISORIES FROM THE NATIONAL HURRICANE CENTER FOR FULL
DESCRIPTION OF THE DEPRESSION AND ITS FORECAST TRACK AND STRENGTH.


EASTERN WV
~~~~~~~~~~
SCATTERED THUNDERSTORMS CAUSED BY DAYTIME HEATING WITHIN A MOIST
AIRMASS ARE EXPECTED OVER AN AREA WITH LOW FLASH FLOOD GUIDANCE
VALUES ACROSS PORTIONS OF EASTERN WV.  THOUGHT IT PRUDENT TO PLACE
A MARGINAL RISK IN THIS REGION.  LOCAL AMOUNTS IN THE 2-4" RANGE
ARE POSSIBLE HERE.


COASTAL CAROLINAS/GA
~~~~~~~~~~~~~~~~~~~~
WITH THE APPROACH OF TROPICAL DEPRESSION #8, EXPECT AN INCREASE IN
RAINS TOWARD THE OUTER BANKS OF NC.  OVER THE NEXT COUPLE OF DAYS,
HOURLY RAIN RATES UP TO 2.5" WHERE CELLS MERGE/TRAIN AND LOCAL
AMOUNTS IN THE 3-5" RANGE ARE POSSIBLE.  HOWEVER, IMPACTED AREAS
ACROSS EASTERN NC ARE PREDOMINANTLY SWAMPY, SO WENT WITH A
MARGINAL RISK OF EXCESSIVE RAINFALL RATHER THAN A SLIGHT RISK,
WHICH MAINTAINS GOOD CONTINUITY.  SEE TROPICAL CYCLONE ADVISORIES
FROM THE NATIONAL HURRICANE CENTER FOR FULL DESCRIPTION OF THE
DEPRESSION AND ITS FORECAST TRACK AND STRENGTH. OTHERWISE...AN
AXIS OF HIGHER MOISTURE ALONG WITH DECAYING FRONTAL BNDRY IN
BROADLY CYCLONIC FLOW WILL MAINTAIN A RISK OF THUNDERSTORMS ACROSS
THE COASTAL CAROLINAS.

ROTH/ORAVEC
$$




USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.