Quantitative Precipitation Forecast
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FOUS30 KWBC 051807
QPFERD

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

...VALID 1806Z 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 SW OKV 20 S CHO 30 N LYH 10 ESE PSK
20 S TRI 15 WNW TRI 15 E JKL 35 NNE CRW.


18Z UPDATE...

MADE ADJUSTMENTS TO BOTH THE NORTHERN PLAINS-UPPER MIDWEST AND THE
CENTRAL APPALACHIANS SLIGHT RISKS BASED ON THE 12Z GUIDANCE.

ACROSS THE NORTHERN-PLAINS-UPPER MIDWEST...SHIFTED THE WESTERN
EXTENT OF THE SLIGHT RISK FURTHER TO THE SOUTH ACROSS WESTERN SD
AND EASTERN WY...BASED LARGELY IN PART ON THE 12Z HI-RES GUIDANCE.

ACROSS THE CENTRAL APPALACHIANS...SHIFTED THE SLIGHT RISK FURTHER
TO THE NORTH AND EAST ACROSS WV INTO WESTERN VA.  HERE ALSO...THIS
ADJUSTMENT WAS BASED IN LARGE PART ON THE 12Z HI-RES GUIDANCE...AS
WELL AS THE LATEST HRRR.

FROM THE LOWER MS VALLEY IN THE CENTRAL GULF COAST STATES...THE
THREAT FOR HEAVY RAIN AND POTENTIAL FOR FLASH FLOODING CONTINUES.
SEE MPD #0307 FOR FURTHER INFORMATION.


15Z UPDATE...

FOR THE AREA OUTLOOKED OVER THE CENTRAL APPALACHIANS...EXTENDED
THE SLIGHT RISK FURTHER TO SOUTHWEST THROUGH CENTRAL KY INTO
MIDDLE TN.  THE 13Z HRRR INDICATES THAT HEAVY RAINS OCCURRING
THERE NOW MAY CONTINUE FOR AT LEAST THE NEXT FEW HOURS...POSSIBLY
EXASPERATING THE FLOODING THAT IS ALREADY OCCURRING ACROSS PARTS
OF THE REGION.

FOR THE UPPER MS VALLEY-NORTHERN PLAINS...EXTENDED THE SLIGHT RISK
FURTHER TO THE WEST ACROSS WESTERN SD INTO FAR NORTHEASTERN WY.
THERE IS AN INCREASING MODEL SIGNAL FOR HEAVY RAINS ACROSS THIS
REGION LATER THIS AFTERNOON-EVENING.  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 AMOUNTS ACROSS
PORTIONS OF THE REGION...ESPECIALLY ALONG THE 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.

FOR THE LOWER MS VALLEY AND CENTRAL GULF COAST STATES..A SEE TEXT
WAS ADDED.  HEAVY RAINS THAT HAVE DEVELOPED ACROSS PORTIONS OF FAR
SOUTHEASTERN AR..NORTHEASTERN LA INTO CENTRAL MS AND SOUTHERN ARE
EXPECTED TO CONTINUE THROUGH AT LEAST THE SHORT-TERM.  THE HWR-ARW
AND NSSL WRF...WHICH BOTH REPRESENT THE CURRENT CONDITIONS FAIRLY
WELL...AGREE ON LOCALLY HEAVY RAINS CONTINUING THROUGH AT LEAST
THE INITIAL HOURS OF THE PERIOD.  REFER TO MPD #0305 AND ANY
FORTHCOMING MPDS FOR FURTHER INFO REGARDING THE HEAVY RAIN/FLASH
FLOODING THREAT ACROSS THIS REGION.

FOR THE SOUTHWEST...A SEE TEXT WAS ADDED AS WELL.  THE  12Z
SOUNDING FROM TUS CONFIRMS THAT A HIGHLY ANOMALOUSLY MOISTURE POOL
REMAINS IN PLACE ACROSS PORTIONS OF THE SOUTHWEST.  THIS MOISTURE
INTERACTING WITH A MID LEVEL IMPULSE IS EXPECTED TO ACCENTUATE THE
POTENTIAL FOR DIURNAL CONVECTION ACROSS PORTIONS OF THE REGION
LATER TODAY...PARTICULARLY ACROSS THE FAVORED TERRAIN OF
SOUTHEASTERN AZ AND ALONG THE EASTERN MOGOLLON RIM FROM
EAST-CENTRAL AZ INTO THE MOUNTAINS OF WESTERN NM.


PREVIOUS DISCUSSION...

...CENTRAL APPALACHIANS...

THE WELL DEFINED AND SMALL CLOSED OFF MID LEVEL SYSTEM OVER THE TN
VALLEY AT THIS TIME 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..WHILE ALSO OPENING UP WITH TIME.  EXPECT A RATHER
ORGANIZED COMMA HEAD/DEFORMATION BAND RAINFALL PATTERN TO PERSIST
WITH THIS FEATURE INTO THE LATER SUNDAY HOURS..PRODUCING MODERATE
TO LOCALLY HEAVY RAINS FROM EASTERN TN/KY INTO SOUTHWESTERN VA AND
SOUTHEASTERN WV.  AREAL AVERAGE 1-2 INCH RAINFALL TOTALS EXPECTED
WITHIN A NARROW BAND..WHICH COULD CAUSE SOME FLOODING CONCERNS IN
A REGION OF GENERALLY LOW FF GUIDANCE VALUES.


...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 BY THE END OF THE PERIOD WILL BE
ACCOMPANIED BY A SEASONABLY STRONG COLD FRONT WHICH WILL ALSO DROP
SOUTH AND EAST INTO THE REGION.  THE COMBINATION OF DECENT HEIGHT
FALLS..FRONTAL CONVERGENCE AIDED BY A WEAK AREA OF LOW PRESSURE
MOVING ALONG THE FRONT SUNDAY NIGHT..AND A STRENGTHENING LOW LEVEL
JET ESPECIALLY LATER SUNDAY AFTERNOON AND NIGHT WHICH WILL BRING
IN HIGHER MOISTURE WITH PWS LIKELY POOLING TO NEAR OR OVER 2
INCHES VICINITY OF THE FRONT..WILL SUPPORT INCREASINGLY ORGANIZED
CONVECTION WITH HEAVY RAINS AS WE GET INTO THE LATER SUNDAY
AFTERNOON AND NIGHTTIME HOURS.  FOR THE MOST PART THE MODEL MASS
FIELDS WERE IN VERY GOOD AGREEMENT ON THIS DEVELOPING
SYSTEM..LEADING TO RATHER HIGH CONFIDENCE IN THE RESULTING
CONVECTIVE EVENT.  QPF-WISE..THOUGHT 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..WHICH WAS GENERALLY SUPPORTED BY THE REMAINDER OF THE
QPF 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.

PEREIRA/TERRY
$$





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