Quantitative Precipitation Forecast
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000
FOUS30 KWBC 270758
QPFERD

EXCESSIVE RAINFALL DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
358 AM EDT WED JUL 27 2016

...VALID 12Z WED JUL 27 2016 - 12Z THU JUL 28 2016...
...REFERENCE AWIPS GRAPHIC UNDER...DAY 1 EXCESSIVE RAINFALL...


SLIGHT RISK OF RAINFALL EXCEEDING FFG TO THE RIGHT OF A LINE FROM
ARA 10 NNW ACP 25 NNW ELD BVX 25 SSW CGI 35 SSW EHR 15 WSW BWG
35 NNW MDQ 25 N NMM 10 S ASD 10 NE NBG 20 WNW 2GL ARA.


LOWER MISSISSIPPI VALLEY
~~~~~~~~~~~~~~~~~~~~~~~~
A MODERATELY STRONG CIRCULATION AT 850 HPA LIFTS UP THE
MISSISSIPPI RIVER TODAY TOWARDS THE LOWER OH VALLEY.  PRECIPITABLE
WATER VALUES ARE SIGNIFICANT, IN THE 2.25-2.5" RANGE.  LOW-LEVEL
INFLOW ACROSS PORTIONS OF LA AND MS IS EXPECTED TO BE IN THE 20-30
KT RANGE THROUGH THE PERIOD, WHICH IN THE PRESENCE OF CAPE VALUES
RISING TO AT OR ABOVE 2000 J/KG COULD CAUSE ISSUES.  THE DEEP
LAYERED FLOW SHOULD BE FAIRLY DEEPLY OUT OF THE SOUTHWEST NEAR AND
EAST OF THE MISSISSIPPI RIVER, WHICH BRINGS THE SPECTER OF CELL
TRAINING.  THE GUIDANCE HAS A STRONG SIGNAL FOR LOCAL 3-5" AMOUNTS
WHICH SHOULD CHALLENGE FLASH FLOOD GUIDANCE VALUES, PARTICULARLY
ACROSS SOUTHERN MS AND EASTERN LA WHERE HEAVY RAINS OVER THE PAST
COUPLE DAYS HAVE PARTIALLY SATURATED SOILS.  A SLIGHT RISK OF
EXCESSIVE RAINFALL HAS BEEN ADDED IN THIS REGION, WHICH SHOULD SEE
THE MOST ORGANIZED CONVECTION THROUGH MUCH OF THE WEDNESDAY INTO
THURSDAY MORNING PERIOD ACROSS THE LOWER 48.

WISCONSIN/MINNESOTA
~~~~~~~~~~~~~~~~~~~
A FRONTAL BOUNDARY SHOULD LURE PRECIPITABLE WATER VALUES OVER 1.5"
INTO THE REGION, WITH LOW-LEVEL INFLOW OF ~ 20 KTS THROUGH 00Z.
MUCAPE VALUES REMAIN NEAR 2000 J/KG OVERNIGHT, AND COULD RISE TO
3000 J/KG DURING THE AFTERNOON HOURS.  THE MESOSCALE GUIDANCE
SHOWS LOCAL MAXIMA IN THE 3-5" RANGE BETWEEN SOUTHERN MN AND
CENTRAL WI, WHICH IS POSSIBLE WITHIN THIS ATMOSPHERIC REGIME
THROUGH 00Z.  A SEE TEXT/MARGINAL RISK OF EXCESSIVE RAINFALL AREA
SHOULD COVER THE FLASH FLOOD RISK FOR WI AND SOUTHEAST MN, WHICH
APPEARS TO BE RELATIVELY ISOLATED.

PORTIONS OF SOUTHERN VA/NORTHEAST NC
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
DEEP WESTERLY FLOW NEAR A FRONTAL BOUNDARY WITH POOLED
PRECIPITABLE WATER VALUES OF NEAR 2" ALONG WITH MODERATE
INSTABILITY (2000-3000 J/KG) AND MODEST LOW-LEVEL INFLOW (~20 KTS)
COULD ORGANIZE CONVECTION AGAIN DURING DAYTIME HEATING.  CELL
TRAINING AND MERGERS ARE CONSIDERED THE MAIN HEAVY RAIN THREAT.
LOCAL AMOUNTS OF 2-4" ARE ADVERTISED IN THE MESOSCALE GUIDANCE
HERE WHICH COULD LEAD TO LOCALIZED ISSUES ON WEDNESDAY.  A SEE
TEXT/MARGINAL RISK OF EXCESSIVE RAINFALL AREA HAS BEEN ADDED TO
THE REGION.

ROTH
$$




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