Winter Weather Affecting Midwest

RIO GRANDE VALLEY:

It was a fairly pleasant day if you live in the Rio Grande Valley.  Afternoon highs were in the low-to-mid 70s in the Valley.  Even cooler temperatures are in store for Friday and Saturday.  For tonight, though, skies will be mostly cloudy with southeast winds at 10-15 mph.  Lows will be in the mid 50s, with patchy fog after midnight.

(1/20): Tomorrow, a cold front will push through the Rio Grande Valley in the afternoon, shifting winds out of the north and north-northwest between 15-20 mph, with gusts up to 30 mph in some areas.  There is a slight chance (20%) of showers as the front passes through, otherwise mostly cloudy.  Highs will reach the lower 70s, but will soon drop after the front has completely passed.  Thursday night will be a bit chilly with partly cloudy skies.  Clouds will keep us from reaching the 30s at night.  Therefore, lows will be in the mid-to-upper 40s by midnight, Friday morning.

(1/21): A very chilly Friday in store.  Skies will be clear with afternoon highs in the mid 50s for most areas of the RGV.  Winds will be out of the north between 10-15 mph, with higher gusts, making the temperature seem colder. Radiational cooling will take place Friday evening, since skies will be clear (heat is radiated into space from the surface of the Earth).  Lows will be in the mid 30s in the upper Valley to the upper 40s near the coast.  Stay warm.  Winds will die down Friday evening and will turn more out of the east and southeast at  5-10 mph.

(1/22): Saturday will be warmer.  Highs will be in the mid-to-upper 60s.  Winds will generally be out of the east between 5-10 mph.  Saturday night will be mostly clear with lows in the mid-to-upper 40s.

Edinburg Forecast:

(1/20): 73/44…Partly to mostly cloudy skies…Winds S.E. shifting to N at 15-20 mph G28 mph…20% chance of a shower or two.

(1/21): 57/42…Sunny skies…Winds N at 10-15 mph

(1/22): 66/36…Sunny skies…Winds E at 5-10 mph

REST OF THE NATION:

A mid-level trough at 700mb is generating some heavy snow over the Midwest region.  Along with this trough, strong warm air advection (WAA) from backing winds (counter-clockwise flow) at 850mb is providing more fuel for the snow in the Midwest.  In addition to the trough and WAA, isentropic lifting is also present in the area, due to frontogenesis occurring over the panhandle of TX. Below are some images of what I’m talking about.  CLICK on each image for better quality.

700mb map valid 00Z 1/20/2011. I circled the area where it is currently snowing in bold yellow. I also included the flow around the trough in red.

300mb map from 00Z 1/20/2011. Something I didn't mention was the divergence at 300mb over the Midwest. Again, bold yellow circle indicated where it is currently snowing.

295 K Isentropic lift. Blue lines are lines of constant pressure. I included arrows that show winds "lifting up" to greater pressure values, thus, lifting air.

850mb map valid 00Z 1/20/2011. A low is visible on the TX/NM border. The backing(counter-clockwise) of winds (WAA) at this level promotes and provides more moisture for the Midwest.

Surface Frontogenesis. Low/Front mostly in its early stages in this area.

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About Brian

University of Oklahoma graduate with a degree in Meteorology. Follow me on Twitter: @WeatherInformer
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