Quantitative Precipitation Forecast
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FOUS30 KWBC 220054
QPFERD

EXCESSIVE RAINFALL DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
853 PM EDT TUE MAR 21 2017

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



0100 UTC UPDATE

HAVE REMOVED MARGINAL RISK AREAS ACRS THE LOWER MS/TN/SE U.S. AS
ACTIVITY CONTINUES TO ACCELERATE SEWD TOWARD REGION OF HIER FFG
VALUES ALONG WITH RAINFALL RATES THAT ARE EXPECTED TO LESSEN WITH
LOSS OF DAYTIME HEATING.  ALSO REMOVED MARGINAL RISK AREA ALONG
THE CA COAST SOUTH OF POINT CONCEPTION AS MAIN BAROCLINIC MSTR
BAND CONTINUES TO SETTLE WELL SOUTH OF THAT REGION.  WEAK UPSLOPE
CONDS ARE EXPECTED ACRS THE ERN ENDS OF THE SACRAMENTO/SAN JOAQUIN
VALLEYS INTO THE WRN SLOPES OF THE SIERRAS WITH SPOTTY .50 TO 1"
ADDITIONAL RAINFALL AMOUNTS EXPECTED OVERNIGHT MAINLY OVER THE NRN
END OF THE SACRAMENTO VALLEY. SULLIVAN   PREVIOUS DISCUSSION
FOLLOWS...

...CALIFORNIA....

THE FULL LATITUDE TROUGH OFF THE WEST COAST WILL AGAIN BECOME
REINFORCED FROM BOTH NORTHERN AND SOUTHERN STREAM COMPONENTS
UPSTREAM -- THIS AS THE INITIAL CYCLONE OFF THE PAC NW BECOMES
ABSORBED INTO THE DEEPENING LOW OFF THE B.C. COAST WEDNESDAY
MORNING. MEANWHILE...THE APPROACHING UPPER LEVEL JET STREAK
ROUNDING THE TROUGH BASE WILL FURTHER AMPLIFY THE SOUTHERN STREAM
WAVE AS IT APPROACHES CA LATE IN THE PERIOD. PRE-FRONTAL
STRENGTHENING ONSHORE SOUTH-SOUTHWESTERLY FLOW IN AN AXIS OF 3-3.5
STANDARD DEVIATIONS ABOVE THE MEAN PW ANOMALIES WILL SUPPORT
WIDESPREAD MODERATE TO HEAVY PRECIP TOTALS FROM THE CENTRAL COAST
RANGE INTO THE SOUTHERN-CENTRAL SIERRA...WHILE THE POST-FRONTAL
WESTERLY FLOW (STILL MOIST YET NOT NEARLY AS ANOMALOUS) WILL
RESULT IN ADDITIONAL MOD-HEAVY PCPN AMOUNTS ACROSS FROM THE BAY
AREA-NORTH COAST AND INTO THE SHASTA/SISKIYOUS AND NORTHERN
SIERRA. IN TERMS OF THE QPF...WPC AGAIN UTILIZED A MULTI-MODEL
BLEND OF (MAINLY) THE HIGHER RESOLUTION GUIDANCE...GIVEN THE
BETTER SENSITIVITY OVER THE TERRAIN.

A MARGINAL RISK OF EXCESSIVE RAINFALL WILL REMAIN ACROSS EASTERN
SACRAMENTO/SAN JOAQUIN VALLEYS INTO THE WESTERN SLOPES OF THE
SIERRA DURING THE DAY 1 PERIOD...AIDED BY THE WET ANTECEDENT
CONDITIONS AND (OVER THE HIGHER TERRAIN) ADDED CONTRIBUTION FROM
SNOW MELT.



HURLEY
$$





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