320
AGUS76 KRSA 151450
HMDRSA
HYDROMETEOROLOGICAL DISCUSSION
NATIONAL WEATHER SERVICE / CALIFORNIA NEVADA RFC / SACRAMENTO CA
750 AM PDT WED APR 15 2026
..SHOWERS OVER NRN CA/NV SRN OR TODAY AS A FRONT MOVES THROUGH
...LINGERING SHOWERS OVER THE SIERRA INTO NV THRS WITH DRYING INTO
THE WEEKEND...
...LARGER UPPER LOW TO BRING MORE WIDESPREAD PRECIP LATE
WEEKEND/EARLY NEXT WEEK...
METEOROLOGICAL CONDITIONS (WED AM - TUE AM)
RADAR IMAGERY SHOWS PRECIP MOVING INTO THE NORTH COAST AND ACROSS
SRN OR AHEAD OF AN APPROACHING COLD FRONT. TPW IMAGERY HAS A NARROW
BAND OF ~1" PW MOISTURE SURROUNDING THE FRONT. AN UPPER LOW IS ALSO
TRAVERSING BC HEADED FOR THE PACNW. SHOWER ACTIVITY OVER NRN CA/NV
AND SRN OR TODAY DUE TO THE FRONT AND UPPER LEVEL SYSTEM. THE LOW
WILL SHIFT INTO THE PACNW LATER TODAY AND GRADUALLY ENTER ID
THURSDAY MORNING AS THE FRONT QUICKLY MOVES THROUGH CENTRAL INTO SRN
CA. THE MOISTURE AROUND THE FRONT WILL PULL OFFSHORE AS IT PUSHES
THROUGH THE STATE ALLOWING PRECIP TO DIMINISH OVER CA LATER TODAY.
LINGERING SHOWERS THURSDAY OVER PARTS OF THE SIERRA AND INTO NV AS
THE TROUGH SWEEPS THROUGH NV FROM NW TO SE. DRY CONDITIONS THEN
RETURN FOR FRIDAY AND HEADING INTO THE WEEKEND AS A RIDGE TRANSITS
THE WEST COAST.
FORECAST UNCERTAINTY FOR THE WEEKEND AND EARLY NEXT WEEK REMAINS
HIGH AS MODELS DISAGREE ON THE TIMING OF THE NEXT BROADER UPPER LOW.
THE GFS REMAINS ON THE SLOWER SIDE HOLDING THE LOW OFFSHORE UNTIL
TUESDAY, ONLY SCRAPING PARTS OF THE COAST WITH LIGHT SHOWERS
INTERMITTENTLY BEFOREHAND AS IT ROTATES WEST OF CA. THE DET ECMWF
CONTINUES TO PREDICT A MUCH EARLIER ARRIVAL WITH SHOWERS REACHING
THE NORTH COAST SATURDAY EVENING AND THE SYSTEM MOVING INTO CA
MONDAY. THE ENSEMBLES ARE DIVIDED AS WELL WITH MORE OF THE ECMWF
MEMBERS FAVORING AN EARLIER ARRIVAL, BUT STILL A DECENT SPLIT OF
ARRIVAL TIMES AND AN OVERALL SLOW DOWN COMPARED TO YESTERDAY. ECMWF
AI ENSEMBLES SHOW SHOWERS REACHING THE NORTH COAST ANY TIME BETWEEN
SATURDAY EVENING AND TUESDAY MORNING. 24 HR QPF CLUSTERS ENDING 00Z
MONDAY SHOW THREE SCENARIOS. CLUSTER 1, WHICH SHOWS 20% CMC 7% GEFS
58% ECMWF, IS THE FASTEST WITH SHOWERS AS FAR SOUTH AS MARIN COUNTY
AND THE CENTRAL SIERRA WHILE CLUSTERS 2 AND 3 ARE CONFINED TO NW CA
TO VARYING DEGREES. THE SLOWER SCENARIOS CONTAIN MOSTLY MEMBERS FROM
THE CMC AND GEFS THOUGH 42% OF THE ECMWF ENSEMBLES ARE SLOWER THAN
THE DET.
ALL THIS TO SAY, THERE IS STILL HIGH UNCERTAINTY IN THE FORECAST FOR
THE WEEKEND AND BEYOND. HAVE CONTINUED THE SLOWER TREND IN THE
OFFICIAL QPF DOING SOME MANUAL DRAWING OF PRECIP EXTENTS DUE TO
PROBABLE OVER SPREADING CAUSED BY THE WIDE RANGE OF TIMINGS IN THE
ENSEMBLES. HAVE VERY LIGHT SHOWERS ALONG THE NORTH COAST EARLY
SUNDAY MORNING GRADUALLY PROGRESSING INLAND AND TO THE SOUTHEAST
SUNDAY/MONDAY. QPF FOR THE CURRENT FRONT/TROUGH: 0.25-0.75" NORTH
COAST (UP TO 1.25" SMITH BASIN), 0.50-1.25" SRN OR CASCADES, AND A
FEW HUNDREDTHS TO 0.30" OR SO FOR THE NORTHERN SIERRA AND THE REST
OF NRN CA. QPF FOR THE WEEKEND LOW: 1-2" NRN CA WEST OF SHASTA, 0.50-
1.25" CENTRAL COAST MOUNTAINS, AND 0.25-0.75" MOST OF THE BAY AREA
(LOCALLY HIGHER ACROSS THE NORTH BAY)/NRN SIERRA/CENTRAL COAST/SAC
VALLEY.
FREEZING LEVELS 8-11 KFT ACROSS THE SIERRA TODAY LOWERING TO 5-11
KFT THURSDAY MORNING BEFORE RISING AGAIN FROM WEST TO EAST FRIDAY AS
THE RIDGE MOVES IN UP TO 9-11 KFT. LEVELS WILL LOWER AGAIN WITH THE
NEXT UPPER LOW APPROACHING, BUT UNCERTAIN AS TO WHEN/HOW MUCH DUE TO
THE BIG DIFFERENCES BETWEEN THE GFS AND ECMWF RIGHT NOW.
PLEASE NOTE: THIS PRODUCT MAY NOT BE ROUTINELY UPDATED.
PLEASE REFER TO THE FOLLOWING PRODUCT ISSUED BY THE CNRFC
WWW.CNRFC.NOAA.GOV/DAILY-BRIEFING FOR A GRAPHICAL SUMMARY OF
WEATHER AND HYDROLOGIC CONDITIONS.
QPF GRAPHICS ARE AVAILABLE AT WWW.CNRFC.NOAA.GOV/QPF.PHP
AS
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