Quantitative Precipitation Forecast
Issued by NWS

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FOUS30 KWBC 220003
QPFERD

EXCESSIVE RAINFALL DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
802 PM EDT THU SEP 21 2017

...VALID 01Z FRI SEP 22 2017 - 12Z FRI SEP 22 2017...
...REFERENCE AWIPS GRAPHIC UNDER...DAY 1 EXCESSIVE RAINFALL...


MARGINAL RISK OF RAINFALL EXCEEDING FFG TO THE RIGHT OF A LINE FROM
30 E SGU 45 W SGU 45 SSE ELY 15 E ENV 45 W OGD 15 E HIF
25 WNW PUC 45 W 4HV 40 SW BCE 30 E SGU.

MARGINAL RISK OF RAINFALL EXCEEDING FFG TO THE RIGHT OF A LINE FROM
20 E BJI BFW ARV 10 W RRL 30 ENE EAU 10 WSW OEO 15 WSW DXX
35 SSW ABR 30 SW FAR 20 E BJI.


GREAT BASIN
~~~~~~~~~~~
A LARGE TROUGH SWINGING THROUGH THE REGION IS PRODUCING COOLING
ALOFT NEAR ITS BASE ACROSS EASTERN NEVADA AND MUCH OF UTAH. THE
PATTERN HAS BEEN FAVORABLE FOR SHOWERS AND RANDOM THUNDERSTORMS
ACROSS PORTIONS OF NV AND UT THIS AFTERNOON.  DRY LOW LEVEL AIR
HAS BEEN LIMITING INSTABILITY AND THE EFFECTIVENESS OF ANY STORMS
THAT MANAGE TO FORM. MU CAPE VALUES ARE JUST NORTH OF 100 J/KG.
GIVEN AN INHERITED MARGINAL RISK AREA, CHOSE TO KEEP IT IN PLACE
ON THE OFF CHANCE THAT DEEP SYNOPTIC ASCENT CAN COMPENSATE FOR
POOR LOW LEVEL MOISTURE TO PRODUCE AN ISOLATED HEAVY RAIN THREAT
OVER SOME OF THE SLOT CANYON / FLASH-FLOOD PRONE TERRAIN IN THIS
REGION OVER THE NEXT FEW HOURS.


UPPER MIDWEST
~~~~~~~~~~~~~
A WARM FRONT WILL SHARPEN BACK WEST ACROSS WI/MN. ISOLATED
INITIATION MAY OCCUR NEAR THE WARM FRONT THIS EVENING...WITH MORE
WIDESPREAD INITIATION EXPECTED IN THE STRENGTHENING WARM ADVECTION
REGIME / NOSE OF THE PLAINS LOW LEVEL JET ACROSS CENTRAL MINNESOTA
AND ADJACENT PARTS OF THE DAKOTAS TONIGHT.  MODEL QPF SIGNAL IS
LACKING IN COVERAGE HERE...BUT STRONG MOISTURE TRANSPORT AND PW
VALUES 1.5 TO 2.5 STANDARD DEVIATIONS FROM CLIMATOLOGY SUGGEST AN
EXCESSIVE RAINFALL THREAT WHEREVER POCKETS OF ORGANIZED CONVECTION
OCCUR. THE RISK CATEGORY IS KEPT AT MARGINAL.

ROTH/BURKE
$$




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