Quantitative Precipitation Forecast
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FOUS30 KWBC 220121
QPFERD

EXCESSIVE RAINFALL DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
919 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
30 SSE 6R6 20 W JCT HYI 20 SSW VCT 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
10 ESE PQI 65 NE PVC 30 SSW ACK 40 ESE BLM JFK 10 W DDH
10 W CMSB.

MARGINAL RISK OF RAINFALL EXCEEDING FFG TO THE RIGHT OF A LINE FROM
40 WSW WMC 10 NW B23 45 WNW P68 65 E NFL 50 SSW NFL 15 NW TVL
50 N BLU 65 S AAT 70 NW LOL 40 WSW WMC.

SLIGHT RISK OF RAINFALL EXCEEDING FFG TO THE RIGHT OF A LINE FROM
35 S MMPG MMPG 25 NE MMPG 15 WSW UVA HDO 40 SSE SSF 10 SW ALI
25 S HBV 55 S MMNL 40 SW MMNL.


SOUTH TEXAS & GULF COAST
~~~~~~~~~~~~~~~~~~~~~~~~
A BROAD CIRCULATION IS LOCATED IN NORTHEAST MEXICO.  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
~~~~~~~~~~~
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. 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 BETWEEN 03-06Z.

ROTH/BURKE/ORAVEC
$$




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