Quantitative Precipitation Forecast
Issued by NWS

Current Version | Previous Version | Graphics & Text | Print | Product List | Glossary On
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29
000
FOUS30 KWBC 160740
QPFERD

EXCESSIVE RAINFALL DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
239 AM EST THU NOV 16 2017

...VALID 12Z THU NOV 16 2017 - 12Z FRI NOV 17 2017...
...REFERENCE AWIPS GRAPHIC UNDER...DAY 1 EXCESSIVE RAINFALL...


MARGINAL RISK OF RAINFALL EXCEEDING FFG TO THE RIGHT OF A LINE FROM
45 WNW MRY 45 SW SQL 30 SW SQL SFO PAO HWD LVK 10 E LVK
20 ESE LVK 15 WSW MOD 10 ESE SCK 20 NNE SCK 15 WSW AUN 15 NE OVE
30 NE CIC 45 NE CIC 60 N BLU 40 N BLU 10 ENE BLU 30 SW TVL
55 NNE MCE 40 NNE FAT 40 NE VIS 35 ENE PTV 30 W IYK 35 ENE BFL
25 SE PTV 10 E VIS FAT 15 W MAE 20 SSW MCE 35 SSW MCE 45 E SNS
30 W NLC 30 NE PRB 20 E PRB 10 NE PRB PRB 15 SSE PRB SBP
10 W SBP 25 WNW SBP 15 S 87Q.

SLIGHT RISK OF RAINFALL EXCEEDING FFG TO THE RIGHT OF A LINE FROM
20 NE VIS 15 ENE MAE 15 NE MCE 20 NE MOD 20 ESE MHR 20 NE BAB
35 ENE OVE 35 N BLU 20 N BLU 20 SSE BLU 45 SSW TVL 45 ENE MCE
30 NNE FAT 35 NE VIS 30 ENE VIS 20 NE VIS.


...CALIFORNIA...

A POTENT AND POTENTIALLY DANGEROUS HEAVY RAINFALL EVENT CONTINUES
TO EVOLVE OVER NORTHERN AND CENTRAL CA EARLY THIS MORNING. PER THE
ESRL ARDT ANALYSIS AND 6 HOURLY GFS-BASED FORECAST...AN
ATMOSPHERIC RIVER WITH AN ATTENDANT ANOMALOUS PLUME OF INTEGRATED
WATER VAPOR TRANSPORT (IVT) WAS DIRECTED INTO NORTHERN CA...
COINCIDENT WITH THE 125+ KT UPPER LEVEL JET STREAK AND 500-300 MB
LAYER PW VALUES ~0.25".

THE ELONGATED NATURE OF THIS AR...SAFELY TUCKED UNDERNEATH THE
LONGWAVE UPPER LOW AND FURTHER FUELED BY ADDITIONAL
DAMPENED...FAST-MOVING SHORTWAVE ENERGY ASSOCIATED ALONG THE NEXT
UPPER JET STREAK...WILL CONTINUE TO SUPPLY ANOMALOUS PWS OF
1-1.25+ INCHES AS IT SLOWLY DIPS SOUTH THROUGH CENTRAL CA IN
RESPONSE TO THE TROUGH PASSAGE/HEIGHT FALLS ACROSS THE PAC NW AND
NORTHERN CA. PW STANDARDIZED ANOMALIES PER BOTH THE SREF AND GEFS
ENSEMBLE MEANS CONTINUE TO BE A ROBUST +2 TO +3...THROUGH THE
PERIOD...TO GO ALONG WITH EQUALLY HEALTHY 850-700 MB MOISTURE FLUX
ANOMALIES OF +3 TO +4 WITHIN THE EXPANSIVE WSW-ENE ORIENTED WARM
CONVEYOR BELT. MOREOVER...MUCAPES OF 100-200 J/KG (BOTH OBSERVED
PER THE LATEST SPC MESOANALYSIS AND PROGGED PER THE GFS/ECMWF WILL
CERTAINLY HELP THE ALREADY-HEALTHY 1-3 HOUR RAINFALL RAINS IN
AREAS OF FORCED OROGRAPHIC ASCENT -- I.E. FROM THE BAY AREA INTO
THE CENTRAL CA COASTAL RANGES AND ESPECIALLY THE WESTERN SLOPES OF
THE SIERRA WITH THE ORTHOGONAL W-WSW LOW-LEVEL FLOW. HOURLY
RAINFALL RATES OF 0.50-0.75" AND 3HR RATES UP TO 1.5" CONTINUE TO
BE NOTED ACROSS THESE AFOREMENTIONED AREAS PER THE BEVY OF
AVAILABLE HIGH-RESOLUTION CAM GUIDANCE. FORECAST AVERAGE
EVENT-TOTAL RAINFALL AMOUNTS OF 1.5 TO 3.0 INCHES (LOCALLY
GREATER) ACROSS THE COASTAL RANGES AND 3-6+ INCHES OVER MUCH OF
THE SIERRA. THESE AMOUNTS WERE SUPPORTED BY THE LATEST GEFS-BASED
RE-FORECAST DATA...AND COULD LEAD TO FLASH FLOODING...ESPECIALLY
IN AND NEAR THE CLUSTER OF BURN SCARS. WPC QPF NUDGED TOWARD AN
ENSEMBLE OF THE 00Z HIGH-RES GUIDANCE (ESPECIALLY THE
WRF-ARW...HREF MEAN...AND NBM... WHICH WAS CLOSE TO CONTINUITY
(PREVIOUS FORECAST).

HURLEY

$$





USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.