Quantitative Precipitation Forecast
Issued by NWS

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000
FOUS30 KWBC 150055
QPFERD

EXCESSIVE RAINFALL DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
754 PM EST SAT JAN 14 2017

...VALID 01Z SUN JAN 15 2017 - 12Z SUN JAN 15 2017...
...REFERENCE AWIPS GRAPHIC UNDER...DAY 1 EXCESSIVE RAINFALL...


MARGINAL RISK OF RAINFALL EXCEEDING FFG TO THE RIGHT OF A LINE FROM
60 WSW MMCS 35 SSE DMN 25 NW LRU 35 ENE TCS 30 WNW 4CR LVS
55 ENE LVS 25 E TCC 20 NNE HOB MDD 65 E FST 15 N 6R6 95 S E38
85 SSW MRF 40 WNW MRF 45 SSW GDP 65 SE MMCS 55 SSE MMCS
50 SSW MMCS.


...NEW MEXICO AND SOUTHWEST TEXAS...

AS OF EARLY SATURDAY EVENING CONVECTIVE CELLS WERE BREAKING OUT
OVER SOUTHERN NEW MEXICO AND SEPARATELY NEAR THE DAVIS MOUNTAINS
IN SOUTHWEST TEXAS. INSTABILITY WAS SOMEWHAT MARGINAL...AND
PRECIPITABLE WATER MAGNITUDE WAS MARGINAL ALTHOUGH CLIMATOLOGICAL
ANOMALIES WERE ON THE HIGH SIDE. THE EARLY
UPDRAFTS...HOWEVER...APPEARED QUITE ROBUST...WITH SUPERCELL
STRUCTURES NOTED IN RADAR IMAGERY FROM SOUTHEAST ARIZONA TO
SOUTHERN NEW MEXICO...SUPPORTED BY STRONG ASCENT AND STRONG SHEAR
PROFILES. LOW LEVEL INFLOW...AND MOISTURE CENTERED AROUND THE 300
K ISENTROPIC LEVEL...WILL ACCELERATE INTO NEW MEXICO AND SOUTHWEST
TEXAS OVERNIGHT...STRADDLING A STATIONARY OR SLOWLY LIFTING
FRONTAL BOUNDARY...AT THE SAME TIME THAT BROAD SCALE HEIGHT FALLS
OCCUR IN ASSOCIATION WITH THE ADVANCING UPPER TROUGH. THIS UPPER
TROUGH REPRESENTS 3 STANDARD DEVIATIONS BELOW CLIMATOLOGY AT 500
MB AND WILL SWING INTO A NEGATIVE TILT BY MORNING. AS SUCH...THIS
WEATHER SYSTEM WILL LIKELY FOSTER SOME SSW-NNE ORIENTED BANDS OF
THUNDERSTORMS PRODUCING MODERATE TO HEAVY RAIN RATES...WITH
COVERAGE EXPANDING ACROSS SOUTHERN AND EASTERN NEW MEXICO...AND
PERHAPS SEPARATELY ACROSS SOUTHWEST TEXAS.

GUIDANCE HAS ONLY RECENTLY BEGUN TO EMPHASIZE THE POSSIBILITY OF
AN ORGANIZED RAIN EVENT OVERNIGHT IN THE TRANS PECOS AND BIG BEND
REGION...POSSIBLY REACHING UP INTO THE PERMIAN BASIN. THE 22Z AND
23Z HRRR LATCH ONTO A QPF SIGNAL HERE...AND THIS SIGNAL SHOWS UP
TO A LESSER DEGREE IN SOME OF THE 12/18Z NCEP HI-RES WINDOWS. WITH
CONVECTION BREAKING OUT AT 00Z NEAR THE DAVIS MOUNTAINS AND GIVEN
THE DEEP LAYER HEIGHT FALLS AND STRONG LOW LEVEL INFLOW IN THIS
ENVIRONMENT...WE EXPANDED THE MARGINAL RISK TO INCLUDE THIS PART
OF TEXAS WHERE 1 TO 2 INCHES OF RAIN COULD OCCUR IN A SHORT TIME.
RELATIVELY HIGH FLASH FLOOD GUIDANCE OVER THE SOUTHERN HIGH
PLAINS...AS WELL AS THE FAST MOTION OF INDIVIDUAL STORMS...ARE
LIMITING FACTORS...KEEPING THE OUTLOOK IN THE MARGINAL CATEGORY
FOR NOW.

BURKE/ORRISON







$$





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