Hazardous Weather Ahead and Outlook for Winter 2009-2010 Dave Reynolds -MTR Dan Keeton - STO Meteorologists in Charge weather.gov/SanFrancisco or /Sacramento.
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Hazardous Weather Ahead and Outlook for Winter 2009-2010 Dave Reynolds -MTR Dan Keeton - STO Meteorologists in Charge weather.gov/SanFrancisco or /Sacramento
Your NWS Weather Forecast Office San Francisco Lightning Our goal: Provide forecasts and warnings so people can make informed decisions.
WFO Product Timeline 7-Day Forecast 3-5 Day Outlook Special Weather Statement Hazardous Weather Outlook Marine Weather Statement Hydrologic Outlook potential imminent
This weather pattern, which features strong zonal flow aimed at portions of the west coast, is likely to last up to a week and maybe longer. The pattern may be related to ongoing activity in the tropics associated with the Madden-Julian Oscillation. This weather pattern is likely to be more transient in nature than that typically observed with El Nino. El Nino does favor additional events of this type – but typically they occur later in the winter (January-February timeframe), and are associated with an amplified wave pattern, eastward extension of the Pacific Jetstream, and persistent pattern of storminess somewhat farther to the south. Developing Stormy Pattern for California
MJO Index -- Recent Evolution The MJO has continued to propagate eastward. The axes (RMM1 and RMM2) represent daily values of the principal components from the two leading modes The triangular areas indicate the location of the enhanced phase of the MJO Counter-clockwise motion is indicative of eastward propagation. Large dot most recent observation. Distance from the origin is proportional to MJO strength Line colors distinguish different months
Storm track and moisture source often associated with the MJO Setup for Atmospheric River
SSMI shows AR stretching across Pacific to Central California Central CA >15 inches rain Atmospheric River
Series of Storms Starting Sunday Night First Storm: Sunday Night – Monday Night More Storms: Tuesday – Next Week Week Remnants of Typhoon NIDA MJO driven thunderstorms Enhanced Jet Cold arctic air to move south and west Sunday H
Winter Outlook Expect possible moderate strength El Nino to persist through spring. Could bring recurrence to weather we will see next week. May not see influence until January Impacts still not certain