Quantitative Precipitation Forecast
Issued by NWS

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FOUS30 KWBC 230113
QPFERD

EXCESSIVE RAINFALL DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
913 PM EDT FRI JUL 22 2016

...VALID 01Z SAT JUL 23 2016 - 12Z SAT JUL 23 2016...
...REFERENCE AWIPS GRAPHIC UNDER...DAY 1 EXCESSIVE RAINFALL...


SLIGHT RISK OF RAINFALL EXCEEDING FFG TO THE RIGHT OF A LINE FROM
20 NNE K9D7 15 ESE FFM 20 W VVV 40 S MBG 35 NE HEI 15 SE SDY
30 WNW ISN 10 S CYEN 20 NNE K9D7.


...NORTHERN PLAINS...

CONVECTION HAS BEEN RAPIDLY EXPANDING OVER THE PAST COUPLE OF
HOURS IN SRN NORTH DAKOTA / NRN SOUTH DAKOTA AS MID-LEVEL HEIGHT
FALLS BEGIN TO OVERSPREAD THE REGION FROM THE WEST. 00Z SOUNDING
FROM BIS SHOWED 4120 J/KG SBCAPE WITH A PWAT OF 1.42 INCHES AND
ONLY SHALLOW LAYERS OF DRY AIR THROUGHOUT THE COLUMN. THE CURRENT
ROUND OF CONVECTION IN THE DAKOTAS IS EXPECTED TO CONTINUE OFF
TOWARD THE EAST INTO A MORE STABLE ENVIRONMENT AS BY CAPPING
INVERSIONS ON AREA SOUNDINGS EAST OF THE DAKOTAS. HOWEVER...AS AS
A POTENT SHORTWAVE CONTINUES TO ADVANCE TOWARD THE NRN HIGH PLAINS
THROUGH 12Z...THE RESPONSE AT THE LOW LEVELS WILL BE FOR 850 MB
WINDS TO INCREASE INTO THE 40-50 KT RANGE AND A SECOND...MORE
DYNAMICALLY DRIVEN...ROUND OF CONVECTION WHICH IS CURRENTLY
ORGANIZING IN ERN MONTANA. RAINFALL RATES OF 1-2 IN/HR HAVE
ALREADY BEEN OBSERVED AND WILL CONTINUE TO BE SEEN THROUGHOUT THE
NIGHT WITH MULTIPLE ROUNDS OF RAINFALL AND CELL MERGERS LEADING TO
EXCESSIVE TOTALS IN A FEW LOCATIONS ACROSS THE SLIGHT RISK AREA.

...ERN NEBRASKA INTO IOWA...

GREATER UNCERTAINTY ACROSS THE MID-MISSOURI VALLEY AS LATEST MODEL
GUIDANCE IS SPLIT ON THE EVOLUTION OF ONGOING CONVECTION ACROSS
THE HIGH PLAINS. WEAKER PERTURBATIONS SEEN ON WV IMAGERY MOVING
OUT OF THE CNTRL ROCKIES AND EVENTUALLY MOVING INTO AN EXTREMELY
UNSTABLE AIRMASS OVER NEBRASKA INTO WRN IOWA WITH 00Z RAOBS FROM
OAX AND DVN IN THE 4000-5000+ J/KG RANGE. EXPANDING CLUSTERS OF
THUNDERSTORMS HAVE BEEN OBSERVED OVER PORTIONS OF THE CNTRL HIGH
PLAINS WITH GRADUAL PROGRESSION OFF TOWRAD THE EAST ACROSS THE
NEBRASKA SAND HILLS. AS THE LOW LEVEL JET STRENGHTENS OVERNIGHT
INTO THE 25-35 KT RANGE...THE NOSE WILL FOCUS INTO ERN NEBRASKA
AND WRN IOWA IN THE 06-12Z TIME FRAME. AT 01Z...A REMNANT OUTFLOW
BOUNDARY WAS OBSERVED OVER NERN KANSAS AND A SYNOPTIC SCALE FRONT
WAS LOCATED WEST TO EAST NEAR SIOUX FALLS SOUTH DAKOTA. LATEST
RUNS OF THE HRRR...HRRR_EXP AND HRRR_PARALLEL INDICATE THE
POTENTIAL FOR A N-S ORIENTED BAND OF NOCTURNAL CONVECTION
DEVELOPING NEAR 12Z IN IOWA WITH OVERRUNNING OF THE LOW LEVEL
BAROCLINIC ZONE WITH DIFFLUENT FLOW ALOFT.

GIVEN THE UNCERTAINTY IN TIMING AND PLACEMENT...A SEE TEXT WAS
KEPT ACORSS THE REGION GIVEN ONGOING ACTIVITY IN NEBRASKA AND
POTENTIAL DEVELOPMENT IN THE 06-12Z TIME FRAME FARTHER EAST INTO
ERN NEBRASKA AND IOWA. LOCAL TOTALS OF 2-4 INCHES WILL BE POSSIBLE
WHICH WOULD BE PROBLEMATIC ACROSS IOWA WHERE FFG IS CURRENTLY 1-2
IN/HR.

OTTO
$$





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