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      Sonoma County Forecast     phone 530-342-1700 
  www.westernwx.com/Sonoma ←Webpage email: forecaster@westernwx.com 
        Monday November 28, 2011 issued 8:30am     by Forecaster Marc Walsh
Text Box: HIGHLIGHTS: Morning fog/low clouds, otherwise mostly cloudy & a little cooler today. Decreasing clouds later today/this evening, then fog/low clouds again. Mostly sunny tomorrow after AM fog/low clouds. Breezy (no more fog) Wed/Thu. Less wind and mild Friday and over the weekend. Dry pattern persisting w/ little chance of rain through mid December.
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Text Box: Short Term Weather Discussion: An upper level trough of low pressure moving over the Pacific Northwest this morning is flattening the West Coast Ridge and also spreading a large swath of mid/high clouds across California. Despite these clouds, fog & low clouds still managed to develop overnight in the valleys of Sonoma County. The fog should lift this morning and partially dissipate only to reveal the clouds above. The clouds should clear out this evening but then we'll be susceptible to more fog & low clouds again developing overnight. Otherwise, a flat ridge of high pressure will remain over the state on Tuesday with mostly sunny skies (after morning fog low & clouds dissipate) and thus some warming. A trough of low pressure from the Gulf of Alaska will begin its plunge southward through the Pacific Northwest late Tuesday.
 
                                   
                                     
                                     
                                     
                                     
                                     
                                     
                                     
                                     
SHORT TERM FORECAST SPECIFICS
Weather Max/Min Dew Pts Chc of Rain Amounts Winds
TODAY Alexander Valley Area LoClds/fog→M Cldy 58-62 38-45 0% none Var 3-10
Lower Russian River & Green Valleys ↓ ↓ ↓ ↓ ↓ ↓
Petaluma/Sonoma/Carneros Areas ↓ ↓ ↓ ↓ ↓ ↓
TONIGHT Alexander Valley Area Partly Cldy w/fog 37-42 37-42 0% none Var 0-5
Lower Russian River & Green Valleys ↓ ↓ ↓ ↓ ↓ ↓
Petaluma/Sonoma/Carneros Areas ↓ ↓ ↓ ↓ ↓ ↓
TUESDAY Alexander Valley Area LoClds/fog→M Sunny 61-65 38-45 0% none Var 3-10
Lower Russian River & Green Valleys ↓ ↓ ↓ ↓ ↓ ↓
Petaluma/Sonoma/Carneros Areas ↓ ↓ ↓ ↓ ↓ ↓
Text Box: Extended Forecast Discussion: Recent forecast models have come to better agreement with their tracking of an "inside slider" trough through the Great Basin on Wednesday and with the development of a closed cutoff low over SE California/western AZ by Thursday morning. This tracking will keep Sonoma County dry but cause breezy north to NE'erly winds Wednesday afternoon through Thursday. The cold air associated with this trough/low looks to remain far enough to our east to prevent any major cooling (although not completely confident that'll be the case). The cutoff low should begin to drift eastward on Friday and pressure gradients will start to relax (so too should the winds). A benign pattern is forecast to set up over the weekend into the early part of next week as a nearly stationary upper level ridge of high pressure amplifies over the Eastern Pacific creating a dry northerly flow aloft over California. A few weak systems embedded within the northerly flow may bring a few high clouds over NorCal from time to time, but otherwise conditions look to be quiet with daytime temperatures running seasonal to a little above average while nights routinely drop close to freezing. At this point medium range models aren't really showing a significant threat of precipitation for California through mid December.
EXTENDED RANGE OUTLOOK                          
    Wed 11/30 Thu 12/1 Fri 12/2 Sat 12/3 Sun 12/4   Trends  Mon 12/5 - Wed 12/7
Weather/Sky M Sunny M Sunny Sunny M Sunny M Sunny Max Temps: Near to above normal
Max Temps 60-65 63-68 60-70 62-66 63-67 Min Temps: Near to below normal
Min Temps 35-40 35-40 30-40 30-40 30-40 Precipitation: Unlikely (thru mid Dec)
Chc of Rain 0% 0% 0% 0% 0% Wx Pattern: California likely to remain on eastern flank of massive EPAC ridge of high pressure
Amounts none none none none none
Winds ↑N 5-25 NE 10-25 E-SE 5-15 E-Var 0-10 E-Var 0-10      
REGIONAL CLIMATE SUMMARY                          
27 November 2011 Precipitation Daily Past Week Today's
      Max/Min 24hr Seas, since 7/1 % Normal ETo ETo Normals Today's Records & Year
Ukiah     62/39 0.00 6.26 89% -- -- 57/39 75 (2002), 20 (1919)
Windsor (103) 55/37 0.00 -- 0.02 0.16 -- --
Sonoma Co Aprt 59/45 0.00 4.63 74% -- -- 61/41 81 (1923), 25 (1948)
Santa Rosa (083) 57/40 0.00 3.94 -- 0.02 0.19 -- --
Bennett Valley (158) 57/33 0.00 3.36 -- 0.02 0.17 -- --
Petaluma E (144) 59/41 -- 0.03 0.21 -- --
Carneros (109) 59/36 0.00 2.40 -- 0.04 0.23 -- --
Sonoma County Weather Station Network
Daily Meteorological Summary
Sunday, November 27, 2011
28-Nov-11
Temperature Avg Avg WIND Precipitation Solar This Morning's
Max time Min time Avg DewPt RH Avg Gust Gust 24hr Season Rad ETo Min Temp
Station:   ºF occur ºF occur ºF ºF % mph mph Dir In. In. cal/cm2 in. °F (7am)
Geyserville-West 62.0 1402 39.7 2056 48.3 ----- 96 0.0 3.3 ---- 0.00 6.24 196 0.04 39.4
Geyserville 62.2 1328 40.9 755 47.7 44.5 90 1.2 6.5 ESE 0.00 5.68 196 0.04 38.8
Alexander Valley 65.6 1405 39.6 2053 47.7 44.2 89 0.8 4.6 E  0.04 5.27 172 0.04 38.8
Lytton   62.6 1451 40.2 2356 47.6 45.0 92 0.6 5.2 NNW 0.00 5.54 181 0.04 38.5
Forestville 58.7 1439 44.1 638 48.3 46.6 94 1.3 5.7 SW 0.01 5.75 156 0.03 42.5
Sebastopol 58.2 1413 41.3 2334 47.8 45.5 92 1.0 5.0 NW 0.00 4.29 ----- ----- 41.6
Graton-South 60.3 1348 39.7 2324 47.8 45.5 92 1.1 5.7 NW 0.00 4.71 ----- ----- 39.3
Sonoma-SW 60.3 1455 38.4 2246 46.8 ----- ----- ----- ----- ----- ----- ----- ----- ----- 37.1
Sonoma-West 60.5 1507 40.2 245 47.2 44.6 92 1.2 6.4 ESE 0.00 4.29 186 0.03 40.4