Weather

088 
fxus65 kbyz 060407 
afdbyz 


Area forecast discussion 
National Weather Service Billings Montana 
907 PM MST Monday Jan 5 2009 


Short term...valid for Tuesday and Wednesday... 


Forecast in good shape with some tweaking this evening. Main 
challenge is winds as Livingston is still pretty wind...but surely 
is below warning criteria and will remain below warning..but will 
likely flirt with advisory criteria at times tonight through 
tomorrow...then probably back up to advisory criteria tomorrow 
late afternoon or more likely tomorrow night. For now...will 
expire the warning and let midnight shift get a good look at GFS 
before making call on issuing a Wind Advisory. These winds are 
already strong in the forecast for this time period. Northwest 
flow causing a few light showers over southern lower elevations...with 
light snow in all mountain areas including crazy and big horns. 
Have raised up probability of precipitation in these locations and kept high already high 
probability of precipitation in Southwest Mountains. Rasch 


Long term...valid for Thursday...Fri...Sat...sun...Mon... 


Extended period will feature upper trough approaching the area 
Thursday...then crossing the region Thursday night with cold front passing 
through the area. Northwest flow aloft will prevail over the area Friday 
Onward with possible waves moving through the flow. 


The models were still in good agreement with the trough approaching 
the area on Thursday. The moisture will be along the system/S warm front 
over northern areas...and along the approaching Pacific cold front. 
Adjusted probability of precipitation Thursday to reflect highest chances over western mountains 
and adjacent lower elevations...and across northern tier in vicinity 
of warm front. 850 mb temperatures will be between +5 and +10 
degrees c and models have been suggesting a warmer day for several 
runs. Thus have raised temperatures well into the 40s and lower 50s 
using the European model (ecmwf) guidance. The upper trough will drag a cold front 
across the area Thursday night. Models have been showing some moisture 
with this feature so raised probability of precipitation over the east in the path of the 
front. May need a wind highlight for favored gap areas on Thursday due to 
strength of the pressure gradient between the system/S surface low 
..and high pressure to the south of the region. 


The system will depart the southeast early on Friday...then northwest flow aloft will 
overtake the region. Raised probability of precipitation to chance in the southeast Friday to cover 
lingering precipitation chances from the system. Otherwise...kept 
the climatological probability of precipitation going through the remainder of the extended 
forecast. There will likely be shortwaves moving through the 
flow...so will need to watch model trends to pin these down. Went a 
little cooler than previous forecast on Friday as models continued to 
show a front backing into the area. Otherwise temperatures looked 
reasonable. Arthur 


&& 


Aviation... 


Gusty southwest winds will continue along the Front Range of the 
beartooths and in the klvm area over the next 24 hours due to a 
persistent trough of low pressure in central Montana. Gusts of 
30-40 kts are likely through the period. Winds may increase again 
late tomorrow and tomorrow night as the trough deepens in response 
to the next upper disturbance. Winds will be less further east... 
and evening gusts of 20-30kts at kbil and k3ht should gradually 
weaken through the night. Otherwise some light snow over the mountains 
will result in frequent obscurations. Snow will intensify over the 
beartooths/absarokas and crazies Tuesday afternoon as the next 
disturbance moves into the region. VFR will prevail across the 
plains. Jkl 


&& 


Preliminary point temp/pops... 


Tuesday Wednesday Thursday Friday Sat sun Monday 
----------------------------------------------------------- 
bil 023/038 028/044 028/049 023/032 020/037 023/043 025/044 
12/o 64/o 32/o 32/S 22/o 22/o 22/o 
lvm 024/039 033/046 036/044 025/033 023/038 025/042 027/043 
43/o 75/o 35/r 32/S 22/o 22/o 22/o 
hdn 020/038 025/043 023/051 016/032 016/038 014/044 020/048 
22/o 76/o 42/o 32/S 22/o 22/o 22/o 
mls 017/032 018/034 018/048 014/025 011/033 013/037 018/040 
22/S 67/S 43/o 42/S 22/S 22/S 22/o 
4bq 018/037 022/039 023/053 019/028 016/035 015/040 017/043 
23/o 67/o 42/o 33/S 22/S 22/o 22/o 
bhk 014/029 015/029 017/046 011/019 007/029 014/034 014/037 
22/S 37/S 43/o 42/S 22/S 22/S 22/o 
shr 016/036 021/044 022/053 018/033 015/038 014/043 017/045 
22/S 66/o 32/o 32/S 22/o 22/o 22/o 


&& 


Byz watches/warnings/advisories... 
Montana...Winter Storm Watch in effect from Tuesday afternoon through 
Wednesday morning for zones 67-68. 
Wyoming...none. 


&& 


$$ 
Weather.Gov/Billings