Friday, December 7, 2007

Oklahoma Weather Update from Emergency Management


I just completed a second conference call and webinar with the National Weather Service and this is their latest information-

It appears the weather event is still on track as previously forecast, with additional information coming together as the event gets closer. The NWS will likely be issuing the first Winter Weather Advisories sometime Saturday evening or night, upgrading them to Warnings (as necessary) on Sunday. Ever-changing factors will affect these decisions but that is how it appears now.

The event is expected to come in two phases or waves, the first precipitation being Saturday evening through Sunday morning, including rainfall and potentially some thunderstorms. Although freezing temperatures may exist in some areas for phase one, they will not be as intensely cold as later in the event, when larger cold air masses will move in. By Sunday morning and mid day a localized (not wide-spread) winter mix is anticipated, probably causing localized glazing of roadways and elevated structures. Later Sunday afternoon or evening phase one will taper off, leaving some “patchy” drizzle in areas and continued potential glazing.

Phase two should arrive overnight Sunday into Monday morning bringing greater precipitation chances and much colder air to central and northern Oklahoma. By mid-day Monday the potentially significant precipitation (comparatively speaking) and colder air will be in place with high temperatures around the upper 20’s and lower 30’s.

As the attached graphic indicates, the potential for icing is present for west-central and north-central parts of the state, including the possibility of western and northwestern Oklahoma County. Accumulations will likely range from ¼” to 1”, depending on specific local conditions. The main corridor as indicated on the graphic may be revised as the system comes closer and specific analysis is reinforced.

Winds are still expected to remain relatively low, 5-15 behind the event with the possibility of stronger winds as the event initially moves through, but calming behind the initial surge.

Expectations are that this event will likely be over by Tuesday morning, although a couple of very weak systems will be moving through at higher altitudes late Tuesday and into Wednesday that may cause possible light precipitation, but nothing serious expected.

Additional information will be provided as available.

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