Quantitative Precipitation Forecast
Issued by NWS

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FOUS30 KWBC 221339
QPFERD

EXCESSIVE RAINFALL DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
938 AM EDT MON AUG 22 2016

...VALID 15Z MON AUG 22 2016 - 12Z TUE AUG 23 2016...
...REFERENCE AWIPS GRAPHIC UNDER...DAY 1 EXCESSIVE RAINFALL...


MARGINAL RISK OF RAINFALL EXCEEDING FFG TO THE RIGHT OF A LINE FROM
55 NE MMCU 95 SSE MMCS 60 S MMCS 25 SW MMCS 20 WSW LRU
25 NE SVC 40 NNW SVC 45 SSE SOW 20 ESE SOW 30 N SJN 55 NE INW
45 SE PGA 40 ENE GCN 30 E 40G INW 15 WNW SOW 35 WSW SOW
60 NE SDL 25 E PRC 20 WSW PRC 35 ESE IGM 40 N IGM 40 SSW SGU
25 WSW CDC 15 SSE MLF 30 SSE U24 55 ESE U24 25 W 4HV 45 E BCE
40 NNE PGA 60 SW 4BL 30 NW 4BL 30 ESE CNY 30 NNE GJT 15 SW EGE
25 N MYP 20 ESE ALS 25 ENE SAF 30 SSE CQC 30 N ROW 15 ESE ATS
30 W INK 25 SSW ODO 10 NNW BPG 25 N SNK 55 S CDS 10 W SPS
15 W 1F0 30 N PRX 30 NE TXK 35 ENE BQP 20 NNE HEZ 15 NNW ACP
20 NE CLL GTU 20 SW ERV 25 ENE MMPG 30 NE MMMV.


SOUTHWEST---SOUTHERN GREAT BASIN---SOUTHERN TO CENTRAL ROCKIES AND
ACROSS PORTIONS OF THE SOUTHERN PLAINS.

THE WESTERN PORTION OF THE MARGINAL RISK AREA COVERS PORTIONS OF
THE SOUTHWEST---SOUTHERN GREAT BASIN INTO THE SOUTHERN TO CENTRAL
ROCKIES.  BROAD UPPER TROFFING IS FORECAST TO PERSIST THIS PERIOD
FROM SOUTHERN CALIFORNIA--INTO THE SOUTHWEST---SOUTHERN GREAT
BASIN---SOUTHERN TO CENTRAL ROCKIES. UPPER DIFFLUENCE MAXIMA
ASSOCIATED WITH SEVERAL SHORTWAVES FORECAST TO ROTATE THROUGH THIS
CYCLONIC FLOW WILL COMBINE WITH PRECIPITABLE ANOMALIES ABOUT 1 STD
DEVIATION ABOVE NORMAL TO SUPPORT ADDITIONAL SCATTERED CONVECTION
ACROSS THESE AREAS.  AREAL AVERAGE LIGHT TO MODERATE TOTALS
EXPECTED---WITH ISOLATED HEAVY TOTALS POSSIBLE---ALONG WITH A
CONTINUATION OF A MARGINAL RISK OF EXCESSIVE RAINFALL AMOUNTS. THE
MORNING UPDATE TRIMMED SOUTHEAST AZ OUT OF THE OUTLOOKED AREAS AS
WATER VAPOR SHOWS DRIER AIR ALOFT ADVECTING INTO THE REGION AND
THE HIGH RES GUIDANCE SHOWS LIGHTER AMOUNTS HERE.


THE SURFACE FRONTAL BOUNDARY CURRENTLY DRAPED FROM THE SOUTHERN
HIGH PLAINS INTO THE LOWER MS VALLEY IS EXPECTED TO BEGIN TO LIFT
NORTHEASTWARD INTO THE SOUTHERN PLAINS THIS PERIOD---WITH THE
CORRESPONDING AXIS OF ABOVE AVERAGE PW VALUES IN THE VICINITY OF
THE BOUNDARY ALSO PRESSING NORTHEASTWARD. SHOWER ACTIVITY SHOULD
INCREASE THIS PERIOD IN THE VICINITY OF THE BOUNDARY OVER THE
SOUTHERN PLAINS...WITH SHOWERS ALREADY MOVING INTO THE REGION FROM
SOUTH TEXAS IN CONFLUENT FLOW LEVEL FLOW. THERE IS SOMEWHAT OF A
MODEL CONSENSUS FOR A MAX PRECIP AREA IN THE VICINITY OF THE
ARLATEX WHERE LOW LEVEL INFLOW INTO THE BOUNDARY MAY MAXIMIZE.
ANOTHER MAX AXIS MAY EXTEND FARTHER TO THE SOUTHWEST OF THIS INTO
SOUTHWEST TX IN A REGION OF UPPER DIFFLUENCE TO THE EAST OF THE
SOUTHWEST UPPER TROF.  ASCENT IS TRIGGERED AS UPPER DIVERGENCE
MAXIMA DEVELOP WITHIN THE DIFLUENT FLOW PATTERN. MODERATE TO
LOCALLY HEAVY PRECIP TOTALS POSSIBLE ACROSS THESE REGIONS---WITH A
MARGINAL RISK OF EXCESSIVE RAINFALL AMOUNTS.

PETERSEN/ORAVEC
$$





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