Wednesday, November 12, 2014

A Cold Wind

This morning was cold and a little windy. Shown are some MesoWest observations of the wind speed and gusts this morning around 7:30. (Click image for bigger picture).








 The reason for the wind is the pressure gradient between Wyoming and Utah. Winds blow from high pressure toward low pressure. Therefore, the cold, dense air blows in from Wyoming. This means our extended warm fall temperatures are pretty much done for. The contours show the high pressure in Wyoming is 1044 mb, and the low pressure in southern Utah is as low as 1010 mb.

The National Weather Service forecast discussion this morning states:
A STRONG 1049MB SURFACE HIGH IS SEEN IN SURFACE ANALYSIS OVER CENTRAL MONTANA AND NORTHEAST WYOMING THIS MORNING...ASSOCIATED WITH AN ARCTIC AIRMASS THAT HAD ENTERED THE GREAT PLAINS. THIS HIGH IS PRODUCING A STRONG NORTH TO
NORTHEASTERLY PRESSURE GRADIENT INTO UTAH...WHICH HAS ALLOWED SOME
OF THE COLD AIR TO SEEP INTO THE AREA. COLDEST SPOTS IN THE FORECAST
AREA AT THIS TIME ARE IN SOUTHWEST WYOMING...THE BEAR RIVER
VALLEY...AND FAR NORTHERN UTAH WHERE SINGLE DIGIT TO NEAR ZERO
TEMPERATURE READINGS ARE BEING REPORTED.
WITH THE GRADIENT REACHING AS FAR AS SOUTHERN UTAH...COOLER MAX TEMPERATURES ARE EXPECTED EVERYWHERE TODAY...WITH 24HR CHANGE OF
AROUND 5 DEGREES ACROSS FAR SOUTHERN UTAH TO 15 DEGREES ACROSS
NORTHEASTERN ZONES. NORTHERN UTAH IS NOT LIKELY TO REACH 40 DEGREES
  AND WILL STRUGGLE TO EVEN REACH THE MID 30S IN MANY AREAS. 
THE CROSS-BARRIER ORIENTATION OF THE SURFACE GRADIENT THROUGH THE
NORTHERN MOUNTAINS HAS PRODUCED LOCALIZED GUSTY CANYON WINDS ALONG
THE WASATCH FRONT AND CACHE VALLEY. OVERNIGHT GUSTS HAVE BEEN IN THE
30-40MPH RANGE AND ARE NOT EXPECTED TO STRENGTHEN MORE THAN ANOTHER
5 OR SO MPH FOR THIS MORNING
DUE TO THE SHALLOW NATURE OF THE
EASTERLIES. THESE WINDS WILL WEAKEN A BIT THIS AFTERNOON...BUT WILL
REMAIN ELEVATED THROUGH THE NIGHT BEFORE THE GRADIENT FINALLY
  RELAXES TOMORROW MORNING.

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