Quantitative Precipitation Forecast
Issued by NWS

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FOUS30 KWBC 160620
QPFERD

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

...VALID 06Z 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
ICL 15 NNW CSQ 10 ESE DSM 30 WSW CID 15 NW MUT 25 W C75
20 N BMI TIP 15 NNW PRG 15 WSW HUF 15 SW AJG 15 ENE SAR
40 WSW FAM 15 S TBN 25 N SGF 60 NNE JLN 20 S IXD 20 SW STJ ICL.



...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...AND THE CONSENSUS
OF HIGH RESOLUTION AND GLOBAL GUIDANCE IS TO SLOWLY MOVE THIS
CIRCULATION ACROSS ND INTO WEST CENTRAL MN BY 17/12Z. 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....

A MESOCYCLONE TRACKING ACROSS NORTHERN MO THIS MORNING WILL MAKE
THE MOST OF THE AVAILABLE INSTABILITY AND PRECIPITABLE WATER
VALUES NEAR 2.00 INCHES TO PRODUCE HEAVY TO LOCALLY EXCESSIVE
RAINFALL ACROSS SOUTHERN IA/NORTHERN MO BEFORE 16/12Z. THE LOW
LEVEL INFLOW REMAINS FAIRLY HIGH...BUT THE INSTABILITY BECOMES THE
LIMITING FACTOR FOR EXCESSIVE RAINFALL SHORTLY AFTER 16/09Z.
MOISTURE AND LIFT REMAIN IN PLACE WITH THE MCV THROUGH THE
REMAINDER OF THE MORNING HOURS.

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 LATE IN THE PERIOD.


HAYES
$$





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