274
NGUS86 KRSA 211337
HCMRSA
HYDROMETEOROLOGICAL COORDINATION MESSAGE
NATIONAL WEATHER SERVICE / CALIFORNIA NEVADA RFC / SACRAMENTO CA
640 AM PDT THU MAY 21 2026
...ABOVE NORMAL TEMPERATURES THROUGH THE WEEKEND AWAY FROM THE COAST
AS HIGH PRESSURE SITS OVER THE E PACIFIC...
...AFTERNOON SHOWERS OVER THE CREST OF THE SIERRA THROUGH SUN,
POSSIBLE LIGHT SHOWERS OVER THE N COAST & CA/OR BORDER MON PM
THROUGH TUES...
METEOROLOGICAL CONDITIONS (THU AM - WED AM)
HIGH PRESSURE OVER THE EASTERN PACIFIC CONTINUES TO INCH CLOSER TO
THE WEST COAST. TEMPERATURES THE REST OF THE WEEK ARE EXPECTED TO BE
WELL ABOVE NORMAL AWAY FROM THE COAST WITH ANOMALIES OF +5 TO +15
DEG F AND LOCALLY HIGHER THROUGH THE WEEKEND. CHANCES OF AFTERNOON
SHOWERS, AND MAYBE A THUNDERSTORM OR TWO, OVER THE CREST OF THE
SIERRA THROUGH THE WEEKEND.
MODELS CONTINUE TO SHOW A A DEEPER TROUGH/UPPER LOW MOVING INTO THE
PACNW EARLY NEXT WEEK BUT DISAGREE ON THE DETAILS. THE 00Z ECMWF NOW
HAS A DEEPER UPPER LOW BRINGING LIGHT PRECIP INTO NW CA MONDAY NIGHT
SPREADING ACROSS THE NORTHERN REGIONAL BORDER THROUGHOUT THE DAY
TUESDAY AS THE SYSTEM DESCENDS INTO NRN CA/NV. THE GFS HAS A
SHALLOWER TROUGH THAT LIFTS NORTHEASTWARD THROUGH ID AND IS MUCH
DRIER, DROPPING ONLY A FEW HUNDREDTHS OF AN INCH OVER THE NORTH
COAST MONDAY NIGHT. THERE IS CONSIDERABLE SPREAD AMONGST THE
ENSEMBLES. THE AI-ECMWF AT ARCATA SHOWS ANYWHERE FROM 0 TO 1.1" FOR
MONDAY NIGHT WHILE THE GEFS HAS LESS THAN HALF ITS MEMBERSHIP
SHOWING ANY PRECIP AT ALL AND EVEN THEN IT IS LESS THAN 0.10".
BOTTOM LINE, UNCERTAINTY IN THE FORECAST BEYOND MONDAY.
HIGH FREEZING LEVELS THE REST OF THE WEEK AT 11.5-13.5 KFT WITH THE
WHOLE AREA LIKELY ABOVE 12 KFT BY THE END OF THE WEEKEND. LEVELS
SHOULD DROP INTO TUESDAY WITH THAT NEXT SYSTEM, BUT BY HOW MUCH WILL
DEPEND ON THE DEPTH OF THAT TROUGH OR LOW.
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
*********************** CONTACT INFORMATION ************************
CNRFC OFFICE HOURS PHONE: 1 (916) 979-3056 EXTENSION 338
AFTER-HOURS CALLING SERVICE: 1 (800) 218-0858
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