Weather

815 
fxus64 kepz 101927 
afdepz 


Area forecast discussion 
National Weather Service El Paso Texas/Santa Teresa nm 
127 PM MDT Friday Oct 10 2008 


Synopsis... 
a strong low pressure system will move across the western United 
States this weekend with the southerly winds ahead of the storm 
pulling tropical moisture into southern New Mexico and western 
Texas. As a result there will be good chances of showers and 
thunderstorms across the region tonight and Saturday. Next week a 
slow moving cold front will bring cooler temperatures and chances 
of rain to the Borderland. 


&& 


Discussion... 
very complex situation developing for the entire forecast period 
with latest model changes and inconsistencies making forecast more 
uncertain. For tonight and Saturday very deep upper low will move 
into Nevada with trailing trough axis extending into southern 
Baja California. Strengthening southerly flow ahead of the trough will advect 
deep abundant moisture associated with hurricane norbet into 
southern New Mexico and western Texas and increasing 
precipitable water to near 1.4 inches over the County Warning Area by Saturday 
morning. Moisture increases will also destabilize air mass with 
convective available potential energy expected from 500 to 1000 j/kg. Moisture increases combined 
with dynamic forcing and cooling aloft should bring scattered 
convection tonight with storms becoming numerous on Saturday. 
While instability will be limited strong vertical wind shear will 
exist by Saturday as 15 knots flow near the surface will increase to 
near 50 knots at 500 mb with about 30 degrees of veering. Thus 
isolated storms may evolve into mesocyclones with locally heavy 
rains and even marginally severe hail. Also an isolated tornado 
should be anticipated on Saturday given the strong shear and 
elevated low level humidities. 


Pattern becomes even more complex Saturday night and Sunday as 
primary low center lifts to the north with secondary trough 
hanging back into Arizona. At moment believe these changes will 
initially create more a westerly flow Saturday night and Sunday 
with advection of warmer drier air aloft bringing seasonably warm 
mostly dry weather Sunday and Monday. But greater uncertainties 
occur by Tuesday and Wednesday as strong back door front drops 
southward into the County Warning Area. Frontal passage should at least lower 
temperatures 10 to 15 degrees. However with trough approaching from the 
west southwest flow aloft over the frontal boundary expected to 
induce isentropic lift with chances of rain. 


Latest GFS now showing a more rainy pattern into the end of next 
week week as another slow moving trough from the west transports 
yet more moisture into the area and causes scattered convection. 
This is in contrast to previous drier GFS and also from latest 
European model (ecmwf) which also has a dry solution after Wednesday. So for now 
will leave extended periods dry until later information shows more 
consistency. 


&& 


Aviation...valid 11/0000z-12/0000z 
VFR conditions through the period. Showers and possible 
thunderstorms tonight and tomorrow. Heavier showers may cause near 
MVFR conditions but nothing below that expected. See appropriate 
tafs for more details. 


&& 


Fire weather... 
cloud cover speeding across the region as moisture moves in from the 
Baja California. Showers expected to start tonight and continue on through 
early Sunday. Winds will increase today and tomorrow as a low moving 
across Nevada and Utah causes a tightened surface gradient. Models 
showing a brief pause in precipitation Sunday and Monday before 
another surge of moisture moves into the region. The exact extent of 
this surge is unsure and may change with each model run. Check the 
latest forecast for updates. 


&& 


Preliminary point temps/pops... 
El Paso 63 81 60 81 60 / 30 60 30 10 10 
Sierra Blanca Texas 59 76 56 81 56 / 30 60 30 10 10 
Las Cruces 60 81 57 79 57 / 30 60 30 10 10 
Alamogordo 56 77 55 77 55 / 30 60 30 10 10 
Cloudcroft 40 55 37 57 37 / 40 70 40 10 10 
Truth or Consequences 57 79 57 75 57 / 30 60 30 10 10 
Silver City 48 70 52 64 52 / 30 60 30 20 20 
Deming 57 80 57 76 57 / 30 60 30 10 10 
Lordsburg 54 79 58 74 58 / 30 50 30 20 20 


&& 


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


$$ 


05 rogash/Adair