775 
fxus64 kepz 202053 
afdepz 


Area forecast discussion 
National Weather Service El Paso Texas/Santa Teresa nm 
253 PM MDT Sat Mar 20 2010 


Synopsis... 
northerly winds behind a cold front that pushed through the region 
Saturday morning kept saturday's temperatures much below normal. 
This new airmass filtering in across the region will allow for a 
cold night tonight. The upper-level storm system that brought 
light lowland rain and mountain snows has exited the region. 
Clear skies...light winds...and dry air will allow for freezing 
temperatures tomorrow morning for most locations. High pressure 
aloft will build into the southwest deserts Sunday. The resulting 
westerly winds will bring drier and warmer weather through 
Tuesday. Another low pressure system with a cold front will move 
into the region Wednesday bringing slight chances for lowland rain 
and better chances for mountain snow showers along with cooler 
temperatures. The system will rapidly exit with conditions 
becoming dry and mild Thursday through next weekend. 


&& 


Discussion... 
this afternoon the region sits under the backside of the exiting 
upper-level storm system that brought wind...rain/snow showers... 
and cooler temperatures to the Borderland. Aloft deep northerly 
flow is importing drier air as evidenced by cloud erosion in 
satellite imagery. At the surface a northerly flow is keeping 
cooler air advecting into the region behind an overnight cold 
frontal passage. Temperatures are running well below normal this 
afternoon...and that highlights our primary concern for the 
short term. 


Tonight temperatures region-wide are expected to drop below the 
freezing mark by sunrise. The freeze is not expected to be deep or 
extended...but sensitive Spring blooms and pets may be adversely 
affected. Will issue a Special Weather Statement to get the word 
out to the public. Otherwise clearing skies due to drying and lighter 
winds overnight and Sunday through Monday as an upper ridge aloft 
builds over the southwest U.S. 


The upper ridge will flatten Monday into Monday night as two 
upper lows track east in the northern and southern branches of a 
split-flow pattern aloft. The southern-branch low is compact and 
tracks east toward the County warning forecast area across the northern Baja California while the 
larger northern-branch low tracks south to The Four Corners. 
Current GFS shows the two systems phasing as they approach the 
region. This gives the area a rapid-fire double shot as the two 
systems follow each other over the forecast area Wednesday 
morning through Thursday morning. Effects don't appear too 
extreme. Winds should become breezy or low-end windy Tuesday-Thursday with 
Lee troughing developing. Moisture is limited so precipitation 
will generally be light and mostly focused over the mountains. A 
backdoor cold front is proged to push in Wednesday night under the 
second low...but cooling looks only moderate and limited to one 
day at best. So it looks like we'll see a 24 hour period of 
increased clouds...slight chances for rain/snow...a period of 
moderate to windy conditions...and slightly below normal 
temperatures but nothing that looks worthy of statements/watches/ 
advisories. 


Behind the exit of the midweek storms we should see a generally 
zonal to weakly ridged pattern aloft. This will bring winds back 
to west and keep winds light to moderate. Results will be 
temperatures back to normal or above. This will also mark a dry 
period as the storm track is shoved north through the weekend. 


&& 


Aviation...valid 21/00z-22/00z... 
winds will diminish after sunset...with light/variable flow 
continuing into Sunday afternoon. VFR conditions will prevail with 
just few-scattered high-based cumulus for the remainder of this afternoon. 


&& 


Fire weather... 
cold airmass behind yesterday's cold front will remain in place 
tonight. Diminishing winds will result in strong rad cooling with 
freezing temperatures expected in all zones by tomorrow morning. Despite 
strong overnight recovery...fairly dry airmass in place will keep 
min relative humidity values in the lower teens across the desert lowlands over the 
next few days...however light winds will prevail. Temperatures will 
quickly recover back to near seasonal normals by Monday afternoon... 
meaning low/middle 70s for The Lowlands. 


Upper level ridge and a developing inversion around 700 mb will 
result in limited mixing heights and low vent rates Sunday and 
Monday. An approaching trough will bring increasing southwest flow 
back to the area Tuesday...improving ventilation rates. 


&& 


25-hardiman 




Preliminary point temps/pops... 
El Paso 30 63 35 74 45 / 0 0 0 0 0 
Sierra Blanca Texas 26 61 33 73 44 / 0 0 0 0 0 
Las Cruces 28 62 31 73 42 / 0 0 0 0 0 
Alamogordo 26 60 30 72 41 / 0 0 0 0 0 
Cloudcroft 14 40 18 51 24 / 0 0 0 0 0 
Truth or Consequences 25 61 31 70 40 / 0 0 0 0 0 
Silver City 21 56 26 65 34 / 0 0 0 0 0 
Deming 26 62 30 72 41 / 0 0 0 0 0 
Lordsburg 27 62 32 73 41 / 0 0 0 0 0 


&& 


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


$$ 


14-bird