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Area forecast discussion 
National Weather Service Midland/Odessa Texas 
525 am CST Monday Nov 23 2009 


Discussion... 
early morning 11-3.9 satellite imagery reveals low cloud and fog 
development over the Stockton plateau. The latest ruc13 and nam12 
low-level relative humidity forecasts suggest development will continue and spread 
north and east through this morning. With this in mind...we have 
increased cloud cover over the Stockton plateau...far eastern 
portions of Pecos County and the southeastern Permian Basin. Most of 
the fog and low clouds is expected to remain along and east of a 
Sanderson...Bakersfield...Garden City line through 15z this morning. 
Otherwise...another day of above normal temperatures is 
expected...with dry air and westerly winds. The warmest readings are 
likely to occur over the upper trans Pecos...including the cities of 
Pecos and Wink...where readings in the lower 80s are expected. A 
cold front will move into the area this evening...and should be 
located along a Van Horn to Iraan line around midnight. Low-level 
moisture ahead of the front should once again allow low clouds to 
develop over the lower trans Pecos and Stockton plateau. The cold 
front should be south of the area by sunrise...with surface high 
pressure to build across the region on Tuesday. Temperatures will 
remain below normal on Tuesday...and especially Tuesday night when 
clear skies...light winds and very dry air remains across all areas. 
We have generally gone at or below the met guidance for low 
temperatures. Southerly winds return on Wednesday and temperatures 
should warm to near normal. A weak cold front is expected to move 
into the region on Thursday with temperatures falling a few degrees 
below normal. We do expect a warming trend for Friday and Saturday 
as a deep trough organizes over the western U.S. Some significant 
differences remain among the medium range models...but the 
operational GFS has trended towards the operational European model (ecmwf) over the 
last several runs. There is some significant spread noted among the 
GFS ensemble data early next week...so confidence this far out is 
low. For now...it appears a fairly strong cold front will move into 
the area on Sunday. Models suggest some precipitation will develop 
over the area on Sunday. For now...we will increase our probability of precipitation...but 
will refrain from mentioning and precipitation until models can 
converge on a solution. 


&& 


Aviation... 
will include an IFR ceiling and MVFR visibility at Midland this 
morning as low level moisture spreads north into the Permian Basin 
this morning. Think veered low level winds will prevent any of the 
other taf sites in southeast New Mexico and West Texas from 
experiencing these conditions. VFR conditions will prevail 
thereafter. Generally southwest to west winds will increase to 
around 15kt this afternoon at most taf sites...with a few higher 
gusts. A cold front will turn winds to the northwest late this 
afternoon...then to the north this evening as the front progresses 
southward. Wind speeds will be in the 10 to 15kt range with a few 
higher gusts as the front passes. 


&& 


Fire weather... 
unseasonably warm temperatures and dry air over the area will allow 
minimum afternoon relative humidity/S to drop to around 15 percent from the Davis 
Mountains and Stockton plateau and northward across the Guadalupe 
Mountains...southeast New Mexico plains and Permian Basin. Since 
fuels have cured...fire danger is high to very high across all 
of these areas. A passing upper level storm system will result in 
20ft wind speeds increasing to around 15 miles per hour in most locations... 
with a few higher gusts. Some locations in the lower elevations of 
the Guadalupe Mountains and southeast New Mexico plains will have 
20ft winds exceed 20 miles per hour at times...however the duration and 
isolated nature of these conditions will prevent the issuance of a 
red flag warning. Will highlight isolated critical fire weather 
conditions in both areas in the severe weather potential statement though. 


A cold front will move into the region this afternoon and shift 
winds to the northwest this evening...followed by another shift to 
the north tonight. The airmass behind the front will be just as dry 
as the current...so recovery tonight will be fair areawide at best. 
Despite cooler high temperatures Tuesday afternoon...minimum 
afternoon relative humidity/S will drop to 15 to 20 percent most locations. 
Portions of the Permian Basin and western Low Rolling Plains could 
also see 20ft winds around 15 miles per hour for a period of time during the 
late morning and afternoon...but critical fire weather conditions 
are not expected. Recovery Tuesday night will be fair to good 
areawide with cold overnight lows expected. 


&& 


Maf watches/warnings/advisories... 
nm...none. 
Texas...none. 


&& 


$$ 


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