Quantitative Precipitation Forecast
Issued by NWS

Current Version | Previous Version | Text Only | Print | Product List | Glossary Off
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 262339
QPFERD

EXCESSIVE RAINFALL DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
738 PM EDT SUN APR 26 2015

...VALID 00Z MON APR 27 2015 - 00Z TUE APR 28 2015...
...REFERENCE AWIPS GRAPHIC UNDER...DAY 1 EXCESSIVE RAINFALL...


SLIGHT RISK OF RAINFALL EXCEEDING FFG TO THE RIGHT OF A LINE FROM
45 ESE PVW 30 WNW AMA 15 NNE DHT 15 SW GUY 25 NW GAG 20 W END
25 E SNL 15 NNE LBR 15 E BAD 30 E ESF 15 NW ASD 35 NNE 1B7
20 NE AXO 10 NNE SRN 15 W KVBS 35 ESE CXO 25 ENE CLL 20 E GTU
20 NNW 6R9 40 W BWD 15 NNE SWW 45 ESE PVW.

MODERATE RISK OF RAINFALL EXCEEDING FFG TO THE RIGHT OF A LINE FROM
20 NE DUC 10 SE ADM 15 E GYI 10 NNW GVT 10 NNE HQZ GKY
30 NW SEP 35 NNE ABI 40 SW F05 30 WNW LTS 20 ESE HBR 20 NE DUC.


....SOUTHERN PLAINS AND LOWER MISSISSIPPI VALLEY...

THERE IS A WELL ADVERTISED BROAD SWATH OF MODERATE TO HEAVY
24-HOUR RAINFALL IN THE GLOBAL AND HIGH RESOLUTION MODELS THROUGH
28/00Z. IN PREVIOUS OUTLOOKS...A MODERATE RISK OF EXCESSIVE
RAINFALL WAS INTRODUCED OVER WESTERN OKLAHOMA...AT THE CENTER OF
PERSISTENT UPPER LEVEL DIFLUENCE AND STRONG EASTERLY LOW LEVEL
INFLOW DURING THE SUNDAY NIGHT AND EARLY MONDAY PERIODS. RECENT
OBSERVATIONAL TRENDS SUGGEST THAT THE HEAVIEST CONVECTIVE RAINFALL
MAY BE DISPLACED...HOWEVER...TO THE SOUTHEAST OF THE STRONGEST MID
LEVEL FORCING. STORMS UP THROUGH 23Z ON SUNDAY WERE MAINLY
SUPERCELLULAR....BUT HAD MANAGED TO TRAIN ON SMALL SCALES...AND
WITH WIDESPREAD INITIATION HAVING OCCURRED AND INCREASING
DEPTH/STRENGTH OF ASCENT...SOME UPSCALE GROWTH IS LIKELY SUNDAY
EVENING. PROPAGATION ALONG OUTFLOWS SHOULD TAKE ACTIVITY BETWEEN
ABILENE AND LUBBOCK TO THE NORTHEAST AND THEN EAST...AS CAPTURED
BY SEVERAL CONSECUTIVE HRRR RUNS AND SOME OF THE 12Z HIGH
RESOLUTION MODELS...ESPECIALLY THE WRF-NMM. ALTHOUGH MOISTURE
PROFILES WERE MARGINAL...THE COVERAGE AND SLOW EVOLUTION OF
CONVECTION WILL LEAD TO HIGHER PROBABILITIES OF EXCESSIVE RAINFALL
FROM TRAINING CELLS. WITH TIME...GULF MOISTURE WILL
IMPROVE...CARRIED INTO NORTH TEXAS AND FAR SOUTHERN OKLAHOMA ON A
30-40 KNOT LOW LEVEL JET. FLASH FLOOD GUIDANCE VALUES ARE IN THE
MID RANGE...AT GENERALLY 1.5 TO 2 INCHES IN 1 HOUR OR 2 TO 2.5
INCHES IN 3 HOURS. SOME LOCATIONS APPEAR LIKELY TO EXCEED THESE
VALUES...AND WE ADJUSTED THE MODERATE RISK AREA TO CENTER ON THE
MORE LIKELY AREA FOR INTENSE CONVECTIVE RAIN RATES THROUGH 06-09Z.

BEYOND THAT TIME...THE TANDEM OF STRONG INFLOW AND INCREASING MID
LEVEL ASCENT SHOULD SPREAD ALONG THE EDGE OF DEEPER RETURNING
MOISTURE OVER EAST TEXAS AND LOUISIANA...WHERE WE MAINTAINED A
SLIGHT RISK. WHILE THIS ACTIVITY SHOULD BE A BIT MORE
PROGRESSIVE...THE STRONG DYNAMIC FORCING ALONG A NARROW PLUME OF
1.5 INCH PLUS PWS COULD LEAD TO SOME POCKETS OF VERY HEAVY
RAIN...WITH SHORT TERM RAIN RATES OF 2 TO 3 INCHES IN AN HOUR OR
TWO.  WITH DOWNSTREAM BLOCKING PATRN HELPING TO HOLD HEIGHTS DOWN
ACRS THE ERN U.S. AND DRIER AIR EXTENDING INTO THE SE
STATES...EXPECT THE STGR STORMS ON MONDAY TO TRACK TOWARD THE
CENTRAL GULF COAST REGION...FINDING DEEP LAYERED E/W AXIS OF
SUB-TROPICAL MOISTURE ALONG THE NRN GULF OF MEXICO.

A SLIGHT RISK AREA ALSO EXTENDS BACK THROUGH WESTERN OK AND THE TX
PANHANDLE...MAINLY FOR ACTIVITY EARLY IN THE PERIOD...WHERE STRONG
LIFT WILL MAINTAIN HEAVIER DOWNPOURS EMBEDDED WITHIN A LARGER
SCALE PRECIPITATION AREA DEVELOPING NORTH OF A CLOSED MID LEVEL
CENTER.

BURKE/SULLIVAN
$$





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