Quantitative Precipitation Forecast
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FOUS30 KWBC 281414
QPFERD

EXCESSIVE RAINFALL DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1014 AM EDT THU JUL 28 2016

...VALID 15Z THU JUL 28 2016 - 12Z FRI JUL 29 2016...
...REFERENCE AWIPS GRAPHIC UNDER...DAY 1 EXCESSIVE RAINFALL...


SLIGHT RISK OF RAINFALL EXCEEDING FFG TO THE RIGHT OF A LINE FROM
50 SSE GLD 20 NW IML 20 SE LBF 25 SW SLN 20 W WLD 25 N WDG
10 NW AVK 25 SW DDC 50 SSE GLD.

SLIGHT RISK OF RAINFALL EXCEEDING FFG TO THE RIGHT OF A LINE FROM
35 ENE TYS 30 NNW CHA 30 NNW DCU 10 WNW MSL 35 WNW MSL 35 E MKL
30 WNW BWG 15 WNW FFT 20 ESE ILN 10 WSW VTA 20 WNW BVI 20 E FKL
25 N FIG IPT 20 WNW FWN HPN FRG 25 SSE JFK 10 E MJX ACY
10 SW GED 15 W CGE 10 ESE DAA 25 SSW SHD 10 NW MKJ 35 ENE TYS.

SLIGHT RISK OF RAINFALL EXCEEDING FFG TO THE RIGHT OF A LINE FROM
30 WNW HEZ 30 ENE IER 20 W SHV 30 ESE OSA 20 ENE OSA 20 E LBR
20 ENE LBR 15 SW DEQ DEQ 15 ESE DEQ 25 NNE TXK 35 SW LLQ
30 NE BQP 40 S GWO 35 NE JAN JAN 30 SW HKS 30 WNW HEZ.


1500 UTC UPDATE

THE SEE TEXT REGION OVER THE ARKLATEX WAS UPGRADED TO A SLIGHT
RISK GIVEN CURRENT RADAR TRENDS AND LATEST GUIDANCE---ESPECIALLY
THE LAST FEW RUNS OF THE HRRR AND HRRR TIME LAGGED
ENSEMBLES---SHOWING POTENTIAL FOR VERY HEAVY RAINFALL AMOUNTS.
VERY SLOW MOVEMENT/AND TRAINING OF CELLS WILL CONTINUE THOUGH THE
REMAINDER OF THE MORNING HOURS BEFORE EARLY AFTERNOON WEAKENING AS
PER LATEST HRRR FORECASTS.  IN AREAS OF TRAINING---2 TO 3 INCH
TOTALS IN AN HOUR POSSIBLE.  PLEASE SEE WPC`S MESOSCALE
PRECIPITATION DISCUSSION #0498 VALID UNTIL 1700 UTC FOR ADDITIONAL
INFORMATION ACROSS THIS AREA.

ONLY SOME SLIGHT CHANGES MADE TO THE ELONGATED SLIGHT RISK AREA
FROM THE TN VALLEY INTO THE MID ATLANTIC.  THE NORTH SIDE OF THIS
AREA WAS EXPANDED NORTHWARD APPROX 40-60NM OVER SOUTHEAST OH INTO
SOUTHWEST PA FOR RADAR TRENDS AND LOWER FFG VALUES.  PLEASE SEE
WPC`S MESOSCALE PRECIPITATION DISCUSSION #0499 VALID UNTIL 1800
UTC FOR ADDITIONAL INFORMATION ACROSS THIS REGION.

ORAVEC

PREVIOUS DISCUSSION

...EASTERN U.S. FROM TENNESSEE TO NEW JERSEY/NEW YORK...

FLASH FLOOD POTENTIAL EXISTS OVER A BROAD AREA TODAY...ALTHOUGH
THE OVERLAY OF MOISTURE / LIFT / INSTABILITY DOES NOT IMMEDIATELY
POINT TOWARD ONE AREA BEING AT GREATER RISK THAN ANOTHER. THE QPF
SIGNAL IS ALSO SOMEWHAT VARIABLE...BUT ALL SOLUTIONS POINT TOWARD
HEAVY AREAL AVERAGE PRECIPITATION FROM EASTERN TN/KY INTO WV AND
SOUTHERN OH...AND MANY SOLUTIONS ALSO POINT TOWARD THE MASON-DIXON
LINE AND 50 MILES TO EITHER SIDE AS A SECOND AXIS OF HEAVY RAIN.

RICH MOISTURE WILL BE SWEPT UP AHEAD OF AN ADVANCING TROUGH...WITH
WIDESPREAD PRECIPITABLE WATER VALUES NEAR/ABOVE 2.0 INCHES RUNNING
ABOUT 2 STANDARD DEVIATIONS ABOVE CLIMATOLOGY. THE TROUGH WAS SET
TO JOIN THE WESTERLIES...WITH SOME ACCELERATION EXPECTED TODAY.
THIS WILL INCREASE THE STRENGTH OF SOUTHWESTERLY LOWER LEVEL FLOW
INTO THE EASTERN TN/OH VALLEYS AND INTO THE UPSLOPE AREAS OF THE
CENTRAL APPALACHIANS. AT THE SAME TIME...FORCING SPILLS OVER INTO
THE MID ATLANTIC...INCLUDING MUCH OF SOUTHERN PA DOWN THROUGH
VA/MD AND EASTWARD...AS MID/UPPER SUPPORT IS ENHANCED WITHIN THE
ENTRANCE REGION OF A DEVELOPING JET STREAK. FORECAST SOUNDINGS
INDICATE A LOT OF HIGH CLOUDINESS WHICH MAY LIMIT INSTABILITY
ALONG THE PATH OF GREATEST FORCING FOR ASCENT...BUT THE LIFT
ITSELF WILL OPERATE ON A DEEPLY SATURATED ENVIRONMENT...AND EVEN
MINIMAL INSTABILITY WOULD BE ENOUGH TO LEAD TO SOME EFFICIENT
RAINFALL PROCESSES. HEAVIER SHORT TERM RAIN RATES ARE POSSIBLE A
LITTLE FARTHER SOUTH IN AREAS OF GREATER HEATING FROM EASTERN TN
INTO VA/MD/DE...ESPECIALLY EAST THROUGH NORTHEAST OF LOW PRESSURE
SETTING UP NEAR I-95 D.C. TO BALTIMORE. ADDITIONALLY...A FEW
SOLUTIONS POINT TOWARD A REDEVELOPMENT OF HEAVY RAIN OVER
SOUTHWEST PA THURSDAY NIGHT IN THE DEFORMATION AREA OF WHATEVER
CIRCULATION MAY CONTINUE TO EXIST EMBEDDED WITHIN THE ADVANCING
TROUGH. THUS THE HEAVY RAIN THREAT MAY PERSIST
OVERNIGHT...ESPECIALLY FROM PA EASTWARD INTO NJ/NY.


...CENTRAL PLAINS...

THE PARAMETERS ARE FAIRLY WELL DEFINED WHICH WILL ALLOW FOR AN
ACTIVE PERIOD OF THUNDERSTORMS WITHIN A WNW FLOW REGIME ACROSS THE
CENTRAL PLAINS STATES CENTERING ON KANSAS. RECENTLY ARRIVED
FRONTAL BOUNDARIES WILL FOCUS THE WESTWARD PUSH OF DEEPER MOISTURE
INTO THE CENTRAL HIGH PLAINS...AND PHASING OF SHORTWAVE ENERGY
COMING DOWN OUT OF MONTANA AND THE DAKOTAS WILL PROVIDE THE
IMPETUS FOR SCATTERED TO NUMEROUS THUNDERSTORMS. THE SHEAR IS
STRONG ENOUGH TO ALLOW FOR SUPER CELLS AND A FORWARD PROPAGATING
SYSTEM OR SYSTEMS. THE REGIME LOOKS TYPICAL OF THE PLAINS...WITH
FLASH FLOOD POTENTIAL TIED MAINLY TO THE EARLY STAGES OF
DEVELOPMENT PRIOR TO FORWARD PROPAGATION AND/OR CELL MERGERS
DURING UPSCALE GROWTH. ANTECEDENT CONDITIONS ARE NOT PARTICULARLY
WET...BUT SOME PARTS OF WESTERN KS HAD RECEIVED ABOVE AVERAGE
RAINFALL IN THE PAST SEVEN DAYS...AND SLIGHTLY ANOMALOUS MOISTURE
CONTENT WILL ALLOW FOR HEAVY RAIN RATES CAPABLE OF EXCEEDING FLASH
FLOOD GUIDANCE VALUES.


...LOWER MISSISSIPPI VALLEY...

BEHIND THE DEPARTING TROUGH THAT WILL BE MOVING TOWARD THE
APPALACHIANS...THERE WILL BE A PERIOD OF CONVERGENT / CONFLUENT
LOWER LEVEL FLOW INTO PARTS OF EAST TEXAS INTO AR/LA AND PERHAPS
ADJACENT TN/MS. MODELS INDICATE POTENTIAL FOR HEAVIER RAINFALL IN
THIS REGION...ESPECIALLY DURING THE MORNING HOURS. WITH RICH
MOISTURE IN PLACE AND POTENTIAL FOR WEST TO EAST TRAINING...A FEW
LOCATIONS COULD EXPERIENCE RAINFALL EXCEEDING FLASH FLOOD GUIDANCE
VALUES. FFG HAD BEEN LOWERED LOCALLY BY HEAVY RAIN THAT OCCURRED
WEDNESDAY.

BURKE
$$





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