Quantitative Precipitation Forecast
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000
FOUS30 KWBC 052103
QPFERD

EXCESSIVE RAINFALL DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
502 PM EDT SUN JUL 05 2015

...VALID 21Z SUN JUL 05 2015 - 12Z MON JUL 06 2015...
...REFERENCE AWIPS GRAPHIC UNDER...DAY 1 EXCESSIVE RAINFALL...


SLIGHT RISK OF RAINFALL EXCEEDING FFG TO THE RIGHT OF A LINE FROM
10 SW FSD 35 WNW YKN 25 ENE VTN 30 ESE IEN 30 W CDR 15 SSE SIB
25 NNE LAR 20 S DRC 25 ESE BFU 20 E IKA 15 W RCA 15 SW PHP
20 ENE PIR 15 WSW ABR 15 SSE DTL 30 SW FOZ 15 NNE ORB 30 N ELO
30 WNW CKC 25 NNE BFW DYT RZN 10 NNE LVN 15 NW MWM 10 SW FSD.

SLIGHT RISK OF RAINFALL EXCEEDING FFG TO THE RIGHT OF A LINE FROM
35 NNE CRW 15 NNE EKN 15 ENE W99 30 SSW OKV 15 NNE CHO
10 SW OMH 10 ESE LKU 15 E OFP 15 N PHF 15 NE ORF NTU CPK RZZ
15 SE MTV 10 WSW GEV 20 S TRI 15 WNW TRI 15 E JKL 35 NNE CRW.


...PORTIONS OF THE NORTHERN PLAINS INTO THE UPPER MS VALLEY...

THE DIGGING OF THE SOUTHWESTERN CANADA H5 TROF INTO THE NORTHERN
PLAINS/UPPER MS VALLEY WILL BE ACCOMPANIED BY A WELL DEFINED COLD
FRONT. FRONTAL CONVERGENCE AIDED BY A WEAK AREA OF LOW PRESSURE
MOVING ALONG THE FRONT SUNDAY NIGHT...WILL SUPPORT INCREASINGLY
ORGANIZED CONVECTION WITH HEAVY RAINS. MOISTURE TRANSPORT BECOMES
PARTICULARLY FOCUSED BY LATE EVENING OVER THE EASTERN HALF OF
SOUTH DAKOTA AND SOUTHWEST MINNESOTA...AS LOW LEVEL JET WINDS
STRENGTHEN TO 35-40 KNOTS AND MOISTURE POOLING / CONVECTIVE
OVERTURNING PUSHES PRECIPITABLE WATER VALUES FROM NEAR 1.5 INCHES
IN THE PRE-CONVECTIVE ENVIRONMENT UP CLOSER TO 2.0 INCHES DURING
THE PRECIPITATION EVENT. MODEL MASS FIELDS WERE IN VERY GOOD
AGREEMENT ON THIS DEVELOPING SYSTEM...LEADING TO RATHER HIGH
CONFIDENCE IN THE RESULTING CONVECTIVE EVENT. THE NAM WAS A BIT
SLOW/NORTH AND WEST OUTLIER WITH ITS HEAVIER RAINFALL AXIS...WHILE
THE NSSL WRF MAY BE A BIT TOO FAST WITH ITS HEAVIER RAINS INTO IA
LATER SUNDAY NIGHT GIVEN THE ANTICIPATED FRONTAL WAVE MAY HOLD
THINGS UP A BIT AT THIS TIME.  WPC QPF WENT IN BETWEEN THESE 2
"OUTLIER" SOLUTIONS...WITH QPF THAT WAS GENERALLY SUPPORTED BY THE
REMAINDER OF THE GUIDANCE. FAIRLY WIDESPREAD 1-2+ INCH RAINFALL
TOTALS LIKELY FROM EASTERN SD INTO MUCH OF MN...WITH SOME ISOLATED
GREATER THAN 3 INCH AMOUNTS POSSIBLE.

BEHIND THE SURFACE FRONT THERE WILL BE A WINDOW IN WHICH HEAVY
RAIN COULD DEVELOP IN THE UPSLOPE REGIME OVER EASTERN WYOMING AND
WESTERN SOUTH DAKOTA. STRONG NORTHEASTERLY FLOW ON THE BACKSIDE OF
THE FRONT DROPPING THROUGH THE REGION...INTERACTING WITH A MID
LEVEL SHORTWAVE MOVING OVER THE TOP OF THE WESTERN U.S. RIDGE AND
RIGHT-ENTRANCE REGION UPPER JET DYNAMICS ARE EXPECTED TO SUPPORT
LOCALLY HEAVY RAIN...ESPECIALLY ALONG FAVORED TERRAIN. THE LATEST
3-HR FFG VALUES ARE LESS THAN 1.5 INCHES ARE PORTIONS OF THE
AREA...SUGGESTING HEAVY RAINS MAY CAUSE FLOODING CONCERNS.


...CENTRAL APPALACHIANS TOWARD SOUTHEAST VIRGINIA...

A WELL DEFINED AND SMALL CLOSED OFF MID LEVEL SYSTEM OVER THE
EASTERN TN VALLEY IS FORECAST SIMILARLY BY ALL OF THE LATEST MODEL
GUIDANCE TO LIFT SLOWLY EAST-NORTHEASTWARD INTO THE CENTRAL
APPALACHIANS/PARTS OF THE SOUTHERN MID ATLANTIC STATES BY MONDAY
MORNING. A STATIONARY FRONT IN SOUTHERN VIRGINIA WILL BECOME A
WARM FRONT...AND HAD ALREADY SERVED AS A FOCUS FOR DEEP CONVECTION
LATE SUNDAY AFTERNOON. EXPECT SLOW MOVING CELLS ALONG THE WARM
FRONT...TO EXHIBIT SOME SHEAR / PROPAGATION TO THE RIGHT...WHICH
COULD LEAD TO TRAINING NEAR THE FRONT IN A MOISTURE RICH
ENVIRONMENT. BACK WEST...INDIVIDUAL CELLS AND SMALL LINE SEGMENTS
WILL CONTINUALLY ROTATE AROUND THE MID LEVEL LOW...WITH RAIN RATES
DIURNALLY ENHANCED BY INSTABILITY EARLY SUNDAY EVENING. EACH OF
THESE MECHANISMS FOR HEAVY RAIN FALL WILL OCCUR WHERE FLASH FLOOD
GUIDANCE VALUES ARE LOW. THE SLIGHT RISK OF EXCESSIVE RAINFALL WAS
EXTENDED EASTWARD ALONG THE FRONT...AND MESOSCALE PRECIPITATION
DISCUSSION NUMBER 308 WILL CARRY ADDITIONAL INFORMATION.


...CENTRAL GULF COAST STATES...

HEAVY RAINS WILL CONTINUE TO SAG TOWARD SOUTHERN LOUISIANA AND
MISSISSIPPI. MORE LOOSELY ORGANIZED ACTIVITY WILL PROPAGATE
WESTWARD ALONG AN OUTFLOW BOUNDARY IN SOUTHERN ARKANSAS THROUGH
MID EVENING. MID AND UPPER LEVEL SUPPORT FOR ASCENT WAS WANING
OVER THIS REGION...AND THE HEAVY RAIN THIS EVENING IS EXPECTED TO
FOCUS OUTSIDE OF LOCATIONS WHICH RECEIVED VERY HEAVY RAIN OVER THE
PAST TWO DAYS. DIMINISHING COVERAGE OF HEAVY RAIN IS EXPECTED
AFTER DARK.


...SOUTHWEST U.S...

MID AFTERNOON CONVECTION WAS BEHAVING IN TYPICAL MONSOON FASHION
ALONG THE MOGOLLON RIM AND IN THE HIGH TERRAIN OF WESTERN NEW
MEXICO. CONVECTION WAS A LITTLE MORE PREVALENT THAN USUAL IN THE
LOWER TERRAIN WEST OF TUCSON...PERHAPS AIDED BY SLIGHTLY DIFLUENT
UPPER LEVEL FLOW AND ARRIVAL OF OUTFLOWS WHICH HAD TRAVELED UP
FROM MEXICO DURING THE MORNING. CLOUD BASE INFLOW WAS NOT
PARTICULARLY STRONG...BUT MODERATE SURFACE DEWPOINTS IN THE MIDDLE
50S WERE CONTRIBUTING TO MODERATE INSTABILITY...AND WITH CELL MEAN
LAYER 0-6 KM WINDS OF 0-10 KNOTS...CELLS WILL BE SLOW MOVING.
SMALL SCALE OCCURRENCES OF MORE THAN AN INCH OF RAIN CAN BE
EXPECTED...WITH AN ASSOCIATED RISK OF FLASH FLOODING.

BURKE/PEREIRA
$$





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