356  
NGUS86 KRSA 011652  
HCMRSA  
 
HYDROMETEOROLOGICAL COORDINATION MESSAGE  
NATIONAL WEATHER SERVICE / CALIFORNIA NEVADA RFC / SACRAMENTO CA  
850 AM PST MON MAR 1 2021  
 
...WIDESPREAD MAINLY LIGHT PRECIP SRN CA/SRN SIERRA/ERN HALF OF NV  
WED INTO THU MORNING...   
..GENERALLY LIGHT PRECIP EXPECTED NRN/CNTRL CA FRI THROUGH SAT
 
 
   
METEOROLOGICAL CONDITIONS (SHORT TERM: MON AM - THU AM)
 
 
AN ELONGATED TROUGH OFFSHORE IS FORECAST TO SPLIT TODAY, WITH THE  
SOUTHERN COMPONENT BECOMING A CLOSED LOW OFF THE CA COAST.  
DOWNSTREAM OF THE LOW, EXPECT DRY CONDITIONS TO CONTINUE OVER THE  
FORECAST AREA FOR THE NEXT 48 HOURS.  
 
BY LATER TUE, EXPECT AN UPPER LOW IN THE GULF OF ALASKA TO BEGIN TO  
SWING THE CA OFFSHORE LOW TO THE EAST AND THEN NE WED. MODEST  
MOISTURE ADVECTION (PW REACHING UP TO AROUND 0.8" NEAR THE COAST)  
AND FORCING FROM THE LOW ALOFT ARE EXPECTED TO CONTRIBUTE TO  
WIDESPREAD MAINLY LIGHT PRECIP ACROSS SOUTHERN CA, THE SOUTHERN  
SIERRA, AND THE EASTERN HALF OF NV WED THROUGH LATE WED NIGHT, WITH  
FREEZING LEVELS 5500-7500 FT. A BLEND OF WPC WITH 50- AND 90-  
PERCENT EXCEEDANCE NBM WAS USED TO BOTH MAKE PRECIP A BIT MORE  
WIDESPREAD EARLY ON AND TO TAMP DOWN WPC AMOUNTS A BIT WITH MOST  
GUIDANCE ON THE LIGHTER SIDE.  
 
   
METEOROLOGICAL CONDITIONS (LONG TERM: THU AM - SUN AM)
 
 
THE S/WV TROF MOVING ACROSS SOUTHERN CA ON WEDNESDAY WILL HAVE  
SHIFTED JUST EAST OF THE LAS VEGAS AREA EARLY ON THURSDAY WITH ONLY  
A FEW SHOWERS REMAINING ALONG THE NV/UT BORDER. OTHERWISE...HIGH  
PRESSURE OVER THE AREA WILL BRING GENERALLY DRY CONDITIONS TO THE  
REGION ON THURSDAY INTO THE FIRST PART OF FRIDAY.  
 
A DEEP UPR TROF OVER THE EASTERN PACIFIC WILL BE GENERALLY ALIGNED  
ALONG 140W AND SLOWLY MAKE ITS WAY TOWARD THE WEST COAST FOR THE END  
OF THE WEEK. 01/00Z MODELS CONTINUE TO SHOW DISCREPANCIES IN TERMS  
OF TIMING THE SYSTEM AND ASSOCIATED MOISTURE PLUME WITH THE GFS  
FASTER THAN THE EC. THE GEFS MEAN IS SLIGHTLY SLOWER THAN THE  
OPERATIONAL MODEL...BUT NOT ENOUGH TO MATCH THE EC. THE EPS MEAN IS  
ACTUALLY FAIRLY CLOSE TO ITS OPERATIONAL RUN. OVERALL...A BLEND OF  
EC AND GFS WAS INCLUDED WITH A TOUCH OF WPC QPF. THIS WILL BRING THE  
INITIAL FRONT EDGE OF THE PRECIP TO THE IMMEDIATE NORTH COAST FRIDAY  
MORNING AND AFTERNOON...BEFORE SHIFTING INLAND ACROSS THE REST OF  
NORTHERN CA LATE FRIDAY INTO EARLY SATURDAY. THEN THROUGH THE DAY  
SATURDAY...PRECIP WILL SPREAD ACROSS CENTRAL CA AND THEN TAPERING  
OFF FOR THE END OF THE PERIOD EARLY SUNDAY MORNING.  
 
FREEZING LEVELS ON FRIDAY MORNING WILL START FROM 6000- TO 9000-FEET  
ACROSS NORTHERN CA WITH 9000- TO 10500- FOR CENTRAL CA. BY THE TIME  
THE SYSTEM MOVES OVERHEAD...LOOK FOR THESE TO BOTTOM OUT FROM ABOUT  
2500-FEET NEAR THE CA/OR BORDER 4000- TO 5000-FEET ALONG THE I-80  
CORRIDOR...AND A SHARP 6000- TO 10500-FEET GRADIENT OVER CENTRAL CA.  
 
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  
LEAVE NAME...OFFICE...AND PHONE NUMBER  
 
LERMAN/KOZLOWSKI  
 

 
 
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