November 21, 2018 - The National Weather Service Hanford office reports the first storm of the season is expected to move through the region beginning Wednesday and continue into Thanksgiving.

Snow levels are expected to drop to around 7000 feet during the precipitation event. Snow amounts will range from 6 to 15 inches with localized amounts of about 20 inches over the highest elevations of the Sierra Nevada.

Elsewhere, rain is expected, mostly over the northern half of the area. Greatest amounts will be in the northern parts of the area with valley locations getting up to half of an inch of rain, while higher amounts up to 2 inches in the highest elevations of the Sierra Nevada in the Yosemite area.

Southern parts of the area will see much less with valley, desert, foothills, and mountains seeing up to a quarter of an inch.

Allow extra travel time during this busy holiday week and slow down on wet roads.

   
  Area Forecast Discussion 
  National Weather Service San Joaquin Valley - Hanford CA 
  401 AM PST Wed Nov 21 2018 
   
  .SYNOPSIS...A low pressure system will bring cooler temperatures, 
  increased moisture and precipitation to the area by this  
  afternoon. Rain and mountain snow will continue into Thanksgiving  
  Day. Another system will bring precipitation chances to the area  
  on Friday and Friday Night then move east of the area over the  
  weekend as high pressure returns along with a drier airmass.  
  
   
  .DISCUSSION...METARs and webcams are indicating much better 
  visibility across the San Joaquin Valley than what was observed on 
  Tuesday morning as an incoming trough has provided for increased  
  atmospheric mixing. IR imagery is indicating some thin high  
  clouds streaming over central CA while the deeper moisture and  
  precipitation remain to the north and west of our area. 
   
  After several days of a dry and stagnant airmass prevailing over 
  the area, a big change is in store as the offshore trough 
  continues to approach the CA coast today and move inland across 
  our area tonight. RH progs are trending slower with the arrival  
  of the deeper moisture moving into our area, but there is still  
  the potential for light precipitation from Fresno County northward 
  by late this morning spreading southward this afternoon. The more 
  significant precipitation is expected to arrive by this evening as 
  the WRF is indicating a 170kt 250mb jet max slicing through 
  central CA. With the northern portion of our CWFA expected to be  
  in the favored LFQ this evening, moderate to locally heavy 
  precipitation will be possible in the Southern Sierra Nevada from 
  Fresno County northward. The biggest concern at this time remains 
  how the Ferguson Fire burn area in Mariposa County responds to  
  the first significant precipitation across our area in a month  
  and a half. The potential exists for mudslides and debris flows  
  in this area so a Flash Flood Watch has been posted for late this  
  afternoon through Thanksgiving morning. This is also expected to  
  be the first significant snowfall of the season across the higher 
  elevations of the Southern Sierra Nevada and a Winter Storm  
  Warning remains in effect for elevations above 7000 feet from for  
  late this afternoon through Thanksgiving morning as well.  
   
  This system will move east of our area by afternoon on  
  Thanksgiving Day. However, a second system is expected to push 
  through Norcal on Thanksgiving Night and spread precipitation 
  southward across our area by Friday morning. Although amounts are 
  progged to be light with this second system, QPF progs are  
  trending a bit higher with it; and this will need to be watched  
  for possible impacts across the Ferguson Fire burn area for  
  Friday. 
   
  By Saturday the second system will move to the east of our area 
  and a dry upper ridge will push into CA on Saturday Night and  
  Sunday. The medium range models are in fair agreement with the  
  ridge remaining the dominant weather feature across our area 
  Sunday through Tuesday which will result in a warming trend and  
  lowering daytime humidities. It will also increase the potential  
  for significant fog in the San Joaquin Valley on Monday and  
  Tuesday mornings. The ridge is progged to break down by next 
  Wednesday, and both the GFS and ECMWF are indicating a potentially 
  strong storm moving through Central CA by the end of next week 
  which would bring additional precipitation to our area. 
 
   
  CERTAINTY... 
   
  The level of certainty for days 1 and 2 is high. 
  The level of certainty for days 3 through 7 is medium. 
   
  Certainty levels include low...medium...and high. Please visit 
  www.weather.gov/hnx/certainty.html for additional information 
  an/or to provide feedback. 

Source: NWS