202 
fxus64 klub 231132 
afdlub 


Area forecast discussion 
National Weather Service Lubbock Texas 
532 am CST Monday Nov 23 2009 


Aviation... 
continued VFR. Early this morning a layer of fog and LIFR stratus 
was apparent about 25 miles east of cds...however this is not 
expected to expand west as light southwesterly winds will be maintained at 
the terminal through the morning. Winds area wide will then veer 
west-northwest this afternoon and increase to around 15 knots ahead of a 
strong cold front. Frontal passage should occur at both lbb and cds around 
00z with the strongest gusts approaching 30 knots confined to cds. 


&& 


Previous discussion... /issued 422 am CST Monday Nov 23 2009/ 


Short term... 
forecast challenges today revolve around a dry...but rather strong 
cold front expected to enter our northern zones by middle afternoon 
before exiting the County Warning Area early this evening. Vorticity maximum currently 
digging over the southern rockies is projected to swing east today and 
in the process carry a Lee trough from eastern nm into the rolling 
plains by the afternoon. Very dry air already in place in eastern nm 
should readily mix east by midday securing one final day of above 
normal warmth...especially off The Caprock where downsloping flow 
will be the greatest. Deeper mixing heights with this drier air 
will also make for some breezy conditions which may create 
difficulty for any controlled Burns...see fire discussion below 
for more details. 


Although the GFS is a tad faster with the cold front today...am 
inclined to side with the slower NAM considering frontal passage should 
occur in our northernmost zones around peak heating and during 
the time of deepest mixing. Thereafter the front should accelerate 
through the remainder of the County Warning Area as the boundary layer decouples. 
Both the NAM and GFS carry an axis of Stout pressure rises to the 
tune of 10mb/6hr through the County Warning Area behind the front...however 
forecast soundings suggest a layer of 40 knots winds around 2k feet above ground level 
will remain within a stable flow. Wind grids nonetheless were 
bumped up immediately behind the front...however values look to 
fall well short of advisory criteria. 


Long term... 
00z NAM was a bit slower with moving the closed low off to the 
northeast of the area while all the other models were fairly 
progressive. Latest 06z NAM has now sped the storm system up a bit 
more in line with the other 00z runs. This is significant because 
there was a possibility of wind speeds Tuesday remaining in the 
breezy range even though high pressure was settling in at the 
surface in the Post-frontal airmass. Now it appears that a fairly 
hard freeze will be in store for Tuesday night into Wednesday 
morning as the center of the high is over the area...light and 
variable winds could develop...and lack of cloud cover all point 
towards very favorable conditions for radiational cooling to take 
place. 


Forecast through Thanksgiving into the latter part of the week 
looks fairly pleasant with northwesterly flow aloft slowly 
transitioning back towards zonal flow by the weekend. Temperatures 
will remain close to normal with only a few weak reinforcing cold 
fronts helping to keep temperatures in check. However...models do 
indicate a change in the pattern for the upcoming weekend into the 
first part of next week. The European model (ecmwf)/GFS and some extent the GFS 
ensembles are now all coming into agreement with a deep 
trough/cutoff low possibly developing across the southwestern United 
States. This should allow some low-level moisture return to take 
place across the area as early as Saturday as southwesterly flow 
aloft ahead of the trough axis/low center initiates surface Lee trough 
development west of the area. This could mean precipitation 
chances could be on the increase for next weekend but it remains 
well too far out to say this with any kind of certainty. Did 
continue non-mentionable probability of precipitation in the forecast for Sunday and 
Monday. Models also shove another strong cold front through the 
region by Sunday/Monday which should help to drop temperatures 
back to at or below normal. Will have to watch and see if and how 
this system will develop before making any significant changes to 
the grids/fcst. 


Jordan 


Fire weather... 
elevated fire weather conditions are expected to develop across 
much of The Caprock this afternoon as relative humidities lower 
to around 12 percent and westerly winds at the 20 foot level 
increase to 15 miles per hour with higher gusts at times. At this time it 
appears the strongest winds /possibly reaching 20 miles per hour for brief 
periods of time/ will occupy the extreme southwest Panhandle and 
northwest South Plains. Considering fuels throughout the area are 
well cured...additional care and preparation should be exercised 
with any controlled Burns this afternoon. Relative humidities will 
improve sharply with the passage of a dry cold front around 
sunset. 


&& 


Preliminary point temps/pops... 
Friona 63 24 53 18 58 / 0 0 0 0 0 
Tulia 68 28 56 20 59 / 0 0 0 0 0 
Plainview 69 28 58 21 59 / 0 0 0 0 0 
Levelland 69 27 58 21 59 / 0 0 0 0 0 
Lubbock 73 31 59 24 59 / 0 0 0 0 0 
Denver City 71 29 59 21 58 / 0 0 0 0 0 
Brownfield 71 31 59 21 59 / 0 0 0 0 0 
Childress 74 37 59 33 63 / 0 0 0 0 0 
spur 74 34 60 27 62 / 0 0 0 0 0 
Aspermont 76 36 61 31 64 / 0 0 0 0 0 


&& 


Lub watches/warnings/advisories... 
none. 
&& 


$$ 


93/14/93