Quantitative Precipitation Forecast
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FOUS30 KWBC 212358
QPFERD

EXCESSIVE RAINFALL DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
757 PM EDT SUN AUG 21 2016

...VALID 01Z MON AUG 22 2016 - 12Z MON AUG 22 2016...
...REFERENCE AWIPS GRAPHIC UNDER...DAY 1 EXCESSIVE RAINFALL...


MARGINAL RISK OF RAINFALL EXCEEDING FFG TO THE RIGHT OF A LINE FROM
20 N KMIU 15 NNW KOPM 40 E PIL 30 ESE BRO 15 WSW MMMA
20 SSW MMRX 60 ENE MMMY.

MARGINAL RISK OF RAINFALL EXCEEDING FFG TO THE RIGHT OF A LINE FROM
40 ENE FFA 35 SSW HSE 10 SSE FAY 15 NW HFF SOP 20 WNW MFV
20 ENE FWN CWPQ.

MARGINAL RISK OF RAINFALL EXCEEDING FFG TO THE RIGHT OF A LINE FROM
25 SE LOL 45 WNW P68 55 SSW P68 15 NNW TPH 10 NNE MMH 55 S TVL
20 SSE BLU 25 NNE BLU 35 ENE RNO 25 SE LOL.

SLIGHT RISK OF RAINFALL EXCEEDING FFG TO THE RIGHT OF A LINE FROM
35 S MMPG MMPG 25 NE MMPG 20 N HDO 30 S BMQ GTU 20 ENE AUS
25 ESE HYI 25 WSW CLL 20 WSW CLL 11R 20 W 5R5 10 SSW ALI
25 S HBV 55 S MMNL 40 SW MMNL.


SOUTH TEXAS & GULF COAST
~~~~~~~~~~~~~~~~~~~~~~~~
WIDESPREAD CONVECTIVE RAINS OVERNIGHT REINFORCED A BROAD
CIRCULATION.  THIS REGION OF MID/UPPER LEVEL FORCING SHOULD
GENERALLY SHEAR OUT AS A NORTHERN STREAM DEEP TROUGH STARTS TO
PULL AWAY FROM THE REGION AND RETURN FLOW STARTS TO SET UP AHEAD
OF A TROUGH OVER THE SOUTHWEST STATES.  THE NET EFFECT OF THESE
CHANGES WILL BE TO LESSEN THE DEGREE OF ORGANIZATION TO THE
CONVECTION OVER SOUTHERN TEXAS...WHERE THE REMAINING FORCING WAS
ALSO SHOWING LESS OVERLAP WITH THE AVAILABLE INSTABILITY
POSITIONED CLOSER TO THE COAST.  SMALL SCALE STORMS CONTAINING
HEAVY RAIN RATES ARE POSSIBLE TONIGHT ACROSS SOUTH-CENTRAL TX AS
LOW-LEVEL INFLOW OVERRIDES THE NORTHERN EDGE OF AN INSTABILITY
POOL IN DEEP SOUTH TX.  WE MAINTAINED A SLIGHT RISK TO ACCOUNT FOR
ONGOING FLOODING AND CONTINUED MODERATE TO LOCALLY HEAVY RAIN
EXPECTED OVERNIGHT IN AREAS OF WET ANTECEDENT CONDITIONS.

LOOSELY BASED THUNDERSTORMS ARE ATTEMPTING TO CONGEAL ACROSS
PORTIONS OF SOUTHERN MS AND SOUTHERN AL AT THIS TIME.  LOCAL
AMOUNTS IN THIS REGION OF 2-4" WOULD NOT BE A SURPRISE WHERE CELLS
MERGE BEFORE THE STORMS DISSIPATE AROUND 03Z.  CHANGES WERE MADE
PER RECENT RADAR TRENDS.


NEW ENGLAND/MID ATLANTIC/NORTH CAROLINA
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
A WELL DEFINED/AMPLIFIED UPPER TROUGH IS SWEEPING THROUGH THIS
REGION.  A NARROW AXIS OF ABOVE AVERAGE PW VALUES...2 TO 2.5
STANDARD DEVIATIONS ABOVE THE MEAN...WILL PERSIST ALONG AND AHEAD
OF THE ASSOCIATED FRONT. STRONG FRONTAL CONVERGENCE IN THIS HIGH
PW AXIS WILL SUPPORT POTENTIAL FOR ORGANIZED FRONTAL/PRE-FRONTAL
CONVECTION AND MODERATE TO HEAVY PRECIPITATION RATES. THE QUICK
MOVEMENT OF THE FRONT AND ASSOCIATED CONVECTION SHOULD BE A
LIMITING FACTOR FOR VERY HEAVY TOTALS. INSTABILITY IS ALSO
QUESTIONABLE, PARTICULARLY ACROSS NEW ENGLAND. THESE LIMITING
FACTORS HAVE KEPT THE PROBABILITY OF EXCESSIVE RAINFALL AT ANY
GIVEN POINT DOWN IN THE MARGINAL CATEGORY.  CHANGES TO THE AREA
WERE MADE PER RECENT RADAR TRENDS.


GREAT BASIN/DESERT SOUTHWEST/SOUTHERN HIGH PLAINS
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
A STREAM OF SHORTWAVE ENERGY STRETCHING FROM SOUTHERN CALIFORNIA
INTO THE SOUTHWEST AND SOUTHERN HIGH PLAINS IS SUPPORTING ANOTHER
ROUND OF WIDESPREAD SCATTERED CONVECTION ACROSS THESE AREAS THIS
FORECAST PERIOD, WHICH COULD PERSIST UNTIL 06Z.  ISOLATED RUNOFF
ISSUES ALSO POSSIBLE OVER PORTIONS OF ARIZONA THIS EVENING.  A
SMALL POCKET OF CONVECTION ACROSS WESTERN NV AND EASTERN CA HAS
ALSO RECENTLY POPPED UP, WHICH COULD CAUSE ISSUES IN ANY NEARBY
BURN SCARS BEFORE DISSIPATING AROUND 03Z.

ROTH/BURKE/ORAVEC
$$





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