Quantitative Precipitation Forecast
Issued by NWS

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910
FOUS30 KWBC 210711
QPFERD

EXCESSIVE RAINFALL DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
310 AM EDT THU JUL 21 2016

...VALID 12Z THU JUL 21 2016 - 12Z FRI JUL 22 2016...
...REFERENCE AWIPS GRAPHIC UNDER...DAY 1 EXCESSIVE RAINFALL...



UPPER MIDWEST/GREAT LAKES/NORTHEAST
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
A CONVECTIVE COMPLEX CURRENTLY ACROSS NORTHERN MN IS EXPECTED TO
DIVE SOUTHEAST ~40 KTS TOWARDS WI THIS MORNING AHEAD OF A WEAK
SHORTWAVE ROUNDING THE TOP OF THE SOUTHERN PLAINS RIDGE,
CHALLENGING THE EDGE OF A CAPPING INVERSION BEFORE POSSIBLY
WEAKENING LATE IN THE MORNING.  THEREAFTER, DAYTIME HEATING AND
BROAD INFLOW OF 30-40 KTS FROM THE SOUTHWEST FROM THE 3000-5000
J/KG SBCAPE UNDER THE CAP TO THE SOUTHWEST (PER THE 21Z SREF MEAN)
SHOULD ALLOW FOR REDEVELOPMENT/REORGANIZATION ACROSS
WI/IL/POSSIBLY EASTERN IA NEAR RESIDUAL OUTFLOW BOUNDARIES THIS
AFTERNOON WITH THE NEW COMPLEX DROPPING SOUTH ACROSS WESTERN
IL/EASTERN IA/TOWARDS EASTERN MO.  PRECIPITABLE WATER VALUES
REMAIN ABOVE THE 90TH PERCENTILE FOR LATE JULY ACROSS THE AREA.
FORWARD PROPAGATION VECTORS SUGGEST A MOVEMENT OF AT LEAST 20 KTS
THURSDAY NIGHT.  THE 00Z NMMB/ARW GUIDANCE, WHICH AMONGST THE
MESOSCALE GUIDANCE HAVE THE BEST GRASP OF THIS SYSTEM, ADVERTISE
LOCAL AMOUNTS IN THE 3-5" RANGE, WHICH COULD FALL QUICKLY.  SHOULD
ANY SHORT BOUTS OF CELL TRAINING OCCUR IN THIS REGIME, HOURLY RAIN
RATES UP TO 2" COULD BE POSSIBLE.  FOR NOW, FORECAST UNCERTAINTY
PRECLUDES A SLIGHT RISK, SO UTILIZED THE SEE TEXT CATEGORY.


SOUTHWEST/ROCKIES
~~~~~~~~~~~~~~~~~
WITH THE STRONG MID/UPPER ANTICYCLONE ANCHORING THE
SOUTHERN/CENTRAL U.S AND TROUGHING INCREASING ACROSS THE
NORTHWEST, ABUNDANT MOISTURE AROUND TWO SIGMAS ABOVE THE MEAN FOR
LATE JULY WILL CONTINUE TO WORK ITS WAY UP INTO THE FOUR CORNERS
REGION. RECENT GUIDANCE SHOWS PWATS MOVING INTO THE 1.50 TO 1.75
INCH RANGE ACROSS SOUTHERN AZ. STRONG SURFACE HEATING COUPLED WITH
THIS MOISTURE LADEN AIR MASS WILL LEAD TO WIDESPREAD THUNDERSTORM
ACTIVITY SPREADING FROM AZ/NM UP INTO THE CENTRAL ROCKIES. THE
HEAVIEST RAINFALL AMOUNTS ARE LIKELY ACROSS THE COMPLEX TERRAIN,
SUCH AS THE MOGOLLON RIM AND WESTERN CO ROCKIES, WHERE LOCAL
OROGRAPHICS WILL LEAD TO MESOSCALE ENHANCEMENTS.  NORMALLY,
ACTIVITY IN THIS REGION IS MODULATED BY DAYTIME HEATING.  HOWEVER,
WITH THE UPPER TROUGH STRENGTHENING ACROSS THE PACIFIC NORTHWEST,
CONVECTION COULD LINGER OVERNIGHT.  A SEE TEXT FOR THE EXCESSIVE
RAINFALL OUTLOOK IN THE FOUR CORNERS REGION TO DEAL WITH LOCALIZED
HEAVY RAIN ISSUES IN WESTERN CO AND THE MOGOLLON RIM OF AZ.

ROTH
$$





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