Quantitative Precipitation Forecast
Issued by NWS

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FOUS30 KWBC 160944
QPFERD

EXCESSIVE RAINFALL DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
543 AM EDT SAT AUG 16 2014

...VALID 12Z SAT AUG 16 2014 - 12Z SUN AUG 17 2014...
...REFERENCE AWIPS GRAPHIC UNDER...DAY 1 EXCESSIVE RAINFALL...


SLIGHT RISK OF RAINFALL EXCEEDING FFG TO THE RIGHT OF A LINE FROM
15 W CWWF 15 NNE CYEN 40 WSW CWEI 20 E MOT 35 WSW K46D
35 W K2D5 30 SSE ABR 20 S HON 35 E PIR 45 SSE 2WX 40 SW 2WX
70 SSE MLS 15 S MLS 10 SW GGW 35 WNW CWKO 15 W CWWF.

SLIGHT RISK OF RAINFALL EXCEEDING FFG TO THE RIGHT OF A LINE FROM
10 NE SAR 25 NNE FAM 20 WNW FAM 10 SSE AIZ 25 S DMO 10 NW SZL
35 SW CDJ 30 SW LWD 25 NE CSQ 10 WNW TNU CID 15 NW MUT 25 W C75
20 N BMI TIP 15 NNW PRG 15 WSW HUF 15 SW AJG 10 NE SAR.



...NORTHERN PLAINS...

CONVECTION IS ONGOING NEAR A FRONTAL BOUNDARY EXTENDING ACROSS
WEST CENTRAL ND EARLY THIS MORNING. THE CONVECTION HAS FORMED IN A
REGION WITH 500-1000 J/KG OF MLCAPE...AND AN AXIS OF 1.70 INCH
PRECIPITABLE WATER VALUES EXTENDING INTO NORTH CENTRAL SD. A SMALL
MID LEVEL CIRCULATION IS DRIVING THE ACTIVITY. THE CONVECTION HAS
BEEN SLOW TO MOVE EASTWARD DURING THE EARLY MORNING...AND KBIS
RADAR SHOWED A MAXIMUM STORM TOTAL PRECIPITATION AMOUNT NEAR 12
INCHES...THOUGH THIS HAS NOT YET BEEN CORROBORATED BY GROUND
TRUTH. INSTABILITY AND MOISTURE ALONG THE AXIS FROM WEST CENTRAL
ND INTO NORTH CENTRAL SD REMAINS IN PLACE DURING THE MORNING
HOURS...AND THE PREPONDERANCE OF HIGH RESOLUTION GUIDANCE
(INCLUDING THE LATEST HRRR AND RAP RUNS) SHOWED THE POTENTIAL FOR
LOCAL 2 TO 4 INCH RAINFALL AMOUNTS ACROSS THE ABOVEMENTIONED AXIS.
THREE HOUR FLASH FLOOD GUIDANCE VALUES ARE AS LOW AS 1.00 TO 1.50
INCHES ACROSS SOUTHWEST ND INTO PORTIONS OF NORTH CENTRAL SD.
WHILE THE BASIN AVERAGE QPF VALUES ARE NOT QUITE THIS HIGH...THE
HIGH MOISTURE CONTENT OF THE AIR SHOULD RESULT IN HIGH RAINFALL
RATES ALONG THE SURFACE BOUNDARY (AS HAVE BEEN OCCURRING EARLY
THIS MORNING). THUS...THE SLIGHT RISK AREA REMAINS IN PLACE
THROUGH 17/12Z.

THE LATEST SSEO MEAN NEIGHBORHOOD GUIDANCE PAINTS THE HIGHEST
PROBABILITIES ACROSS SOUTH CENTRAL ND INTO WESTERN CENTRAL SD.
THIS IS ALONG THE FRONTAL BOUNDARY AND AXIS OF BEST PRECIPITABLE
WATER VALUES (WHICH PEAK BETWEEN TWO AND THREE STANDARD DEVIATIONS
ABOVE NORMAL) THROUGH 16/18Z. AFTER THAT TIME...THE BEST MOISTURE
AND INSTABILITY WEAKEN AS THE MID LEVEL SYSTEM CROSSES ND INTO
WEST CENTRAL MN. THERE COULD BE SOME ADDITIONAL HEAVY RAINFALL IN
WEST CENTRAL MN...BUT THREE HOUR FLASH FLOOD GUIDANCE VALUES ARE
HIGHER HERE...SO THE SLIGHT RISK AREAS WAS NOT EXTENDED THIS FAR
EAST.


...MIDWEST....

CONVECTION CONTINUES EARLY THIS MORNING AHEAD OF AN MCV ACROSS
NORTHWEST MO. THE LOW LEVEL INFLOW HAS PEAKED NEAR 50 KNOTS (AS
SEEN ON LOCAL VWP)...AND THE ELEVATED INSTABILITY HAS PUSHED THE
CONVECTION INTO SOUTHERN IA. THE TREND IN THE LAST HOUR OR SO WAS
FOR THE ACTIVITY TO WEAKEN AS IT OUTRUNS THE INSTABILITY TO ITS
SOUTHWEST...DESPITE THE STRONG INFLOW. A GENERAL WEAKENING TREND
IN THE LOW LEVEL INFLOW SHOULD CONTINUE THROUGH 16/15Z...AND WITH
IT THE HEAVIEST RAIN POTENTIAL. BOTH THE LATEST HRRR AND RAP SHOW
SOME ACTIVITY WITH THE MCV THROUGH 16/15Z...SO A SLIGHT RISK WILL
BE MAINTAINED THROUGH THE WEAKENING PHASE OF THE CONVECTION THIS
MORNING.

THE MCV WILL CONTINUE TO FOCUS INSTABILITY AND MOISTURE INTO THE
EVENING HOURS. THE LOW LEVEL INFLOW INCREASES AGAIN AFTER 17/00Z
ACROSS EASTERN MO AND WEST CENTRAL IL. PRECIPITABLE WATER VALUES
REMAIN IN THE TWO STANDARD DEVIATION ABOVE NORMAL RANGE (BETWEEN
1.75 AND 2.00 INCHES) ALONG AND NORTH OF THE FRONTAL BOUNDARY AS
THE LOW LEVEL INFLOW INCREASES...AND THERE IS A MULTI MODEL SIGNAL
THAT AN MCS COULD FORM OVER EASTERN MO AFTER 17/03Z... AND TRACK
ACROSS WEST CENTRAL IL THROUGH THE END OF THE PERIOD. A SWATH OF
1.00 TO 1.50 INCHES OF QPF WAS PLACED ALONG THE TRACK OF THE
POSSIBLE MCS. WHILE THE BASIN AVERAGED QPF IS NOT ABOVE THE THREE
HOUR FLASH FLOOD GUIDANCE VALUES...THE HIGH RAINFALL RATES COULD
LEAD TO FLASH FLOODING...AND THIS AREA WAS INCLUDED IN THE SLIGHT
RISK FOR AFTER 17/00Z.


HAYES
$$





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