Quantitative Precipitation Forecast
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FOUS30 KWBC 250056
QPFERD

EXCESSIVE RAINFALL DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
853 PM EDT SUN MAY 24 2015

...VALID 01Z MON MAY 25 2015 - 12Z MON MAY 25 2015...
...REFERENCE AWIPS GRAPHIC UNDER...DAY 1 EXCESSIVE RAINFALL...


SLIGHT RISK OF RAINFALL EXCEEDING FFG TO THE RIGHT OF A LINE FROM
20 NNW FAM 30 W CGI 20 SW CIR 30 S CIR 30 NE DYR 15 NNE MKL
30 SSE MKL 15 E JAN 15 S HDC 25 N GSM 10 SE KEIR 10 WNW KEIR SRN
20 W BTR 40 S HEZ 10 S HEZ 25 NNE HEZ 10 NW TVR 35 S GLH
25 NNE GLH 20 SW UTA 15 WSW AWM 20 SE JBR 20 NE ARG 35 WNW POF
50 NNE UNO 20 SSE TBN 25 SW TBN 20 ENE SGF 15 SSW SGF 35 NNE ROG
25 N ROG 25 ENE GMJ 15 SSW JLN 25 N JLN 45 SW SZL 20 NNW SZL
20 E CDJ 25 N IRK 20 NW EOK 15 SE EOK 15 W PPQ 15 WNW SUS
20 NNW FAM.

SLIGHT RISK OF RAINFALL EXCEEDING FFG TO THE RIGHT OF A LINE FROM
10 S GXY 15 WNW ARL 25 ENE BVR 35 SW WRL GEY 25 NNE GEY
30 NW SHR 20 ENE PIN 50 NE DGW 30 NE TOR 25 SSW AIA 25 E SNY
35 W IML 50 NNW GLD 25 N ITR 20 WNW ITR 35 WNW ITR 35 NNW LIC
10 S GXY.


...SOUTHERN TO CENTRAL PLAINS AND LOWER TO MID MS VALLEY...

LATEST DISCUSSION...

MADE CHANGES HERE..MAINLY TO SIGNIFICANTLY SHRINK THE PREVIOUS
SLIGHT RISK AND REMOVE THE PREVIOUS MODERATE RISK COMPLETELY.  THE
PROGRESSIVE NATURE OF THE SOUTHERN PLAINS TO LOWER MS VALLEY MID
LEVEL TROF HAS SIGNIFICANTLY LESSENED THE FLOODING THREAT THRU AT
LEAST THIS PERIOD..WITH ONLY 2 AREAS HAVING EVEN A SLIGHT CHANCE
OF SOME HEAVY RAINS/ISOLATED FLOODING PROBLEMS.  THE 1ST AREA IS
BASICALLY THRU MO..AND AT LEAST EARLY IN THIS PERIOD..BACK IN THE
OZARKS..WHERE FF GUIDANCE VALUES ARE RATHER LOW.  THE MORE
IMPRESSIVE LARGE SCALE LIFT/COMMA HEAD TYPE DEVELOPMENT WITH THE
MAIN H5 S/WV COULD PRODUCE SOME LOCALLY HEAVY RAINS FROM
SOUTHWESTERN MO UP INTO NORTHEASTERN MO..ALONG THE TRACK OF THE
S/WV..BUT AGAIN ONLY SOME VERY ISOLATED FLOODING CONCERNS MAY
EXIST.  THE OTHER AREA OF SOME CONCERN IS FROM THE MID INTO THE
LOWER MS VALLEY..WHERE A SLOW MOVING LINE OF CONVECTION WITH SOME
TEMPORARY CELL TRAINING IN ADVANCE OF THE TAIL END OF THE H5 TROF
COULD PRODUCE SOME LOCALLY HEAVY RAINS.  THRU THIS REGION..FF
GUIDANCE VALUES ARE CONSIDERABLY HIGHER..SO AGAIN ANY FLOODING
PROBLEMS ARE LIKELY TO BE QUITE ISOLATED EVEN WITH SOME LOCAL 1-2
INCH RAINS IN AN HOUR OR SO.


PREVIOUS DISCUSSION...

...HEAVY RAINFALL POTENTIAL SHIFTS SLOWLY EASTWARD ACROSS EASTERN
PORTIONS OF THE SOUTHERN AND CENTRAL PLAINS AND TOWARD THE LOWER
AND MID  MISSISSIPPI VALLEY...

AN AFTERNOON UPDATE WAS SENT TO REMOVE NORTHWEST IA TO SOUTHERN MN
FROM THE THREAT AREA AS HIGH QPF AMOUNTS ARE FORECAST FURTHER
SOUTH WITH NO MODELS REMAINING FORECASTING HEAVY RAIN INTO SOUTH
DAKOTA OR MN.

THE PRIMARY MORNING ADJUSTMENT WAS TO TRIM THE WESTERN EDGE OF THE
THREAT AREA WHERE ACTIVITY HAS ENDED IN CENTRAL KS DOWN TO
SOUTHEAST TEXAS.  ONE MORE CIRCULATION DRIFTING EAST TOWARDS
NORTHEAST TEXAS WARRANTS CONTINUING A SLIGHT RISK THERE.

THE WIDESPREAD CONVECTION ORIENTED IN A SSW-NNE FASHION EARLY THIS
MORNING IS ALIGNED PARALLEL TO THE MID-UPPER LEVEL FLOW...HAS
EXHIBITED SLOW EASTWARD PROGRESSION EARLY THIS MORNING. THE NEXT
IN WHAT HAS BEEN A SERIES OF SHORTWAVES ROUNDING THE TROUGH BASE
WILL LIFT NORTHEAST ACROSS THE RED RIVER AND INTO THE MID
MISSISSIPPI VALLEY BY THE END OF THE PERIOD (12 MON).  THE ROBUST
LLJ (40-50 KTS) AND ANOMALOUS PW VALUES OF 1.75 AND 2.00 INCHES
(~2.5 STANDARD DEVIATIONS ABOVE NORMAL) SUPPORTS CLUSTERS/SEGMENTS
OF HEAVY DOWNPOURS.  THE BIGGEST DIFFERENCE FROM YESTERDAY IS THE
MORE LOCALIZED COVERAGE OF HEAVY RAINFALL POTENTIAL IN THE
MODEL/HIGH RESOLUTION ENSEMBLES.

THE MODELS CONTINUE TO SHOW SPREAD IN THE EASTWARD
PROGRESSION/FORWARD PROPAGATION OF THE CLUSTERS OF SHOWERS/STORMS.
WPC UTILIZED THE RGEM AND OTHER HIGH-RES GUIDANCE (SUCH AS THE
WRF-ARW) TO NUDGE THE ACTIVITY A BIT MORE TO THE EAST...GIVEN THE
ANTICIPATION OF STRENGTHENING DEEP-LAYER INSTABILITY DOWNSTREAM
WITH MUCAPES CLIMBING BETWEEN 2000-3000+ J/KG INTO PORTIONS LA AND
AR THIS AFTERNOON. THERE ARE A FEW GLOBAL AND HIGH RES MODELS
WHICH INDICATE BANDS OF HEAVY SHOWER/STORMS SPREADING EAST INTO MS
SO A SLIGHT RISK WAS EXPANDED INTO WESTERN MS.

FARTHER NORTH INTO EASTERN KS/NE AND NORTHERN MO/IA...AHEAD OF THE
MESOSCALE CONVECTIVE CIRCULATION TRACKING TO THE NORTHEAST...THE
DEEP-LAYER INSTABILITY WILL NOT BE AS GREAT...SO THE THREAT IS
STILL SLIGHT GIVEN SOME MODEST INSTABILITY (MUCAPES GENERALLY
UNDER 1500 J/KG) ALONG WITH THE ANOMALOUS PW AND 850-700 MB
MOISTURE FLUX...LOCALLY HIGHER AMOUNTS ARE EXPECTED PER THE HIGH
RES GUIDANCE. AS A RESULT...THE SLIGHT RISK FOR EXCESSIVE RAINFALL
WILL CONTINUE ACROSS THESE AREAS.


...CENTRAL TO NORTH CENTRAL HIGH PLAINS...
MADE ONLY MINOR CHANGES TO THE PREVIOUS AREA HERE.  SCATTERED TO
LOCALLY NUMEROUS SHOWER ACTIVITY IS LIKELY AGAIN IN THIS ABOVE
AVERAGE PW AXIS WITH 700-500 MB VERTICAL VELOCITY MAXIMA ROTATING
AROUND THE BROAD CIRCULATION LEADING TO A LOCALLY HEAVY RAINFALL
OVER PORTIONS OF CENTRAL AND SOUTHEAST WY INTO FAR WESTERN NE AND
NORTHEAST CO. THIS COINCIDES WITH A MAX REGION OF UPPER DIFFLUENCE
AS WELL AS SOUTHEAST-EAST LOW-LEVEL UPSLOPE FLOW AND FAVORABLE
MOISTURE TRANSPORT. LOCALIZED HEAVY RAIN ARE POSSIBLE WHERE CELLS
MOVE SLOWLY...AND CONSIDERING THE RECENT HEAVY RAINS (LOW FFG
VALUES OF 1.5" OR LESS IN 6 HOURS)...ADDITIONAL LOCALIZED
SHORT-TERM RUNOFF ISSUES ARE ANTICIPATED.

PETERSEN/TERRY
$$





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