Another two days of mild weather then winds on the increase Thursday leading to cold snowy weekend
Tuesday November 16, 2010
Posted at 9:16 am by Howard
A Rex Block has already established itself near the dateline with a negative tilt upper ridge transporting cold Arctic air via the Bering Sea into the Gulf of Alaska. The lead short wave is now in the Gulf of Alaska sporting an Ht 500, 528dm upper center. Over the next 24 hours… more Arctic air wrapping into the upper low will push the upper center south to near 55N/145W, while our off shore ridge at 140w becomes ever so squashed. During the next few days, a rather large 500-1000mb thickness pool of 516dm covers much 0f the Gulf of Ak and is diffluent into the surface low spinning up off the BC coast Wednesday morning. Temperatures at 700mb over Alaska are between -20c & -25c. Pretty cold for Mid November. The 500MB Height Anomaly showed a center, greater then -36 Deca-Meters off the Oregon coast Saturday night. This is one deep upper low for Mid November. These heights would be more common later in December. No wonder the upper jet is so strong and why it will be a particularly windy storm with the potential for Blizzard conditions later in the weekend along the 395 corridor and here locally in town.
Preliminary QPF from HPC is 1.3 inches over the crest by Saturday night. However, it is way too early to speculate on snowfall amounts until we get closer to Friday. All the Dweebs will says is that there is “the potential” for several feet of snow over the upper elevations. As a note, there is not any subtropical tap shown now, like was indicated some 5 days ago. Nevertheless, with an upper jet this strong, and an unusual amount of cold air aloft and good over water trajectory, this system will generate plenty of its own moisture!
Long Range Week 2:
The Dweebs are still expecting a break for the traveliers of the Thanksgiving Holiday. The 8 to 14 days outlooks show normal precip beginning the 23rd through the 29th. The weather for Thanksgiving at the moment shows upper ridging and thus fair weather.
Dr Howard and the Dweebs………………………………:-)
Reference Weather Glossary