521 
fxus64 kepz 202157 
afdepz 


Area forecast discussion 
National Weather Service El Paso Texas/Santa Teresa nm 
257 PM MST Thursday Nov 20 2008 


Synopsis... 
a cold front pushed into the Borderland during the afternoon and 
colder air will move in overnight. Minimal moisture is in place so 
only a few low clouds over east slopes are expected tonight. Most 
locations will experience a light freeze by morning. With cold air 
in place tomorrow lowland temperatures will maximum out in the 50s. 
Weak upper level ridging will help to warm temperatures back to 
normal by Saturday with a seasonal and dry weekend in store. 


&& 


Discussion... 
a flat broad ridge aloft resides over the southwest U.S. This 
afternoon. At the surface a large high pressure center is dropping 
south through the central U.S. Plains. This system is pushing a 
cold front through our County warning forecast area. It is already through most of the 
forecast area and the temperatures at epia are starting to drop after 
maxing at about 1230 local time. Low stratus has banked up against 
the east slopes of the Sacramento/Guadalupe Mountains there is very 
little and very shallow moisture in our atmosphere and not much 
associated with the airmass. Thus don't see any precipitation with the 
front but do expect some stratus to develop over more of the area 
tonight. 


Cooler temperatures for tomorrow with continued/southeast push from the 
surface high sliding by to the east. Expect lowland to be in the m50s 
east to near 60 out west. Weak ridging aloft will keep the area 
dry and provide plenty of sun. By Saturday the surface high slides 
east away from the region into the southeast U.S. Aloft ridging becomes 
better established. This will allow for a modification of the 
airmass which will warm the regional temperatures back up to normal. 


Sunday a weak upper low off the Baja California looks to turn middle and high 
level trajectories back to west and SW. This may add some high clouds 
to the area...but low level will remain dry. 


For the rest of the week the GFS model shows US under a quasi- 
zonal flow. Embedded in this flow appears to be several waves. 
None of them look to have sufficient moisture or dynamics to 
provide our area any precipitation. However some periods of high 
and middle level clouds are likely. As we get to Thursday the model 
increases moisture from the south so well have to watch later 
model runs for the potential for having to add probability of precipitation. 


&& 


Aviation...valid 21/0000z-22/0000z... 
strong back-door cold front will sweep through area today and 
overnight from the northeast. Look for widespread IFR and LIFR ceilings 
with asscd Post frontal stratus...to continue for extreme NE and eastern Otero 
and Hudspeth counties through 05z. Otherwise VFR condts will prevail 
across flying area. Frontal passage will bring a wind shift to the 
east-northeast early...then to the east-southeast generally after 
midnight. Sustained winds behind the front will likely range from 15 
to 25 kts...with gusts as high as 35 to 40 kts. West slopes of area 
mountains...ridge-tops...passes and gaps...are most likely to see 
the higher gusts. MDT or greater turbulence surface-080 above ground level also psble along 
and immediately west of area mountains 


&& 


Fire weather... 
weak ridge aloft will re-build into the area on Sunday...followed by 
a gradual transition to southwesterly sub-tropical flow through for 
first half of next week. This will occur ahead of a developing low 
pressure trough currently forecast to move into the area later 
next week. As a result...an increase in high cloudiness with a 
warming trend can be expected for our fire weather zones beginning 
later this weekend. 


&& 


Preliminary point temps/pops... 
El Paso 32 56 31 65 38 / 0 0 0 0 0 
Sierra Blanca Texas 30 52 32 61 33 / 0 0 0 0 0 
Las Cruces 31 56 29 64 34 / 0 0 0 0 0 
Alamogordo 28 52 29 60 33 / 0 0 0 0 0 
Cloudcroft 24 43 22 48 26 / 0 0 0 0 0 
Truth or Consequences 30 55 30 62 33 / 0 0 0 0 0 
Silver City 29 51 28 60 31 / 0 0 0 0 0 
Deming 30 59 28 64 34 / 0 0 0 0 0 
Lordsburg 31 61 29 65 35 / 0 0 0 0 0 


&& 


Epz watches/warnings/advisories... 
nm...none. 
Texas...none. 
&& 


$$ 


14/22 bird/Tripoli