Thursday Morning Update

Thursday, November 8th 2012, 6:08 am
By: Alan Crone

Our weather will be mostly uneventful today but south winds will be increasing in the 15 to 30 mph range this afternoon as pressure falls occur east of the Rockies as a major upper level system moves closer to the Pacific Northwest during the next 24 hours. This means a good chance of storms will occur Sunday across Eastern OK. 

Friday and Saturday very strong southerly surface flow will advect low level moisture from the Gulf into the southern and central plains.  This will result in clouds for most of the Friday and Saturday period with wind speeds that may reach advisory levels during this period. Despite the increase in humidity, the fire danger will be elevated today through Saturday due to the increase of gusty south winds combined with the continued drying of vegetation across the state.  

The main upper level trough will induce a surface area of low pressure across the northern high plains that will eventually move into Minnesota Sunday morning.  A surface cold front will extend southward across Eastern Kansas and Western OK Saturday afternoon before the front moves eastward Sunday morning.  A few of the earlier runs of both the NAM and GFS indicated a secondary surface low could form on the boundary Saturday evening across Northwestern OK.  This may act to allow for a backing of surface winds into the boundary for a short window Saturday evening and would promote a small window for super cell thunderstorm development.  The data this morning is not as bullish on this secondary low along the boundary. The main upper air profile combined with the flow being parallel to the surface boundary should quickly allow storms to become linear (squall line type feature) and move eastward across the state Sunday evening.  The surface instability Sunday will be limited across Eastern OK but a few storms could become severe.  Almost all available guidance suggest the front will clear the area Sunday late into pre-dawn Monday as much colder air spreads across the state.  This would result in Sunday morning temps in the mid-60s falling into the upper 40s by late Sunday evening.  Mondays temps would start in the lower 30s and stay in the upper 40s with thickness values and 850 temps supporting a chilly afternoon.   

Most of the model data is fairly progressive with the trough and surface boundary meaning the precipitation would be east of the state by early Monday morning.  The only exception is yesterday's run of  the extension of the NAM (DGEX) which slows down the trough, drops colder air in the 850mb level across Northern OK, and keeps moisture in this area until Monday afternoon.  This would create winter precipitation across SE Kansas and northeastern OK.  This is the only model data suggesting the potential for the column of cold air to deepen as moisture remains near the area.  Therefore I will make no mention of this long shot scenario, but of course, will watch the data and observations closely for course corrections for the Monday forecast.  

The EURO and GFS both suggests the potential for another system approaching by the end of next week with another good chance for rain.  Stay tuned! 

Our official high temp from Tulsa International was 66 recorded at 3:09pm.

The daily average high for today is 65 with the low of 43.  Daily records include 85 from 2005 and 16 from 1991.

Precipitation for the year remains at  26.68"  which is -9.66 below the average precip for the year to date.


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