787 
fxus65 kbyz 181500 
afdbyz 


Area forecast discussion...updated 
National Weather Service Billings Montana 
900 am MDT Friday Jul 18 2008 


Short term...valid for today and Sat... 


Decent short wave moving over northern half of our forecast area 
this morning. Have bumped up probability of precipitation with coverage wording. Rest of 
forecast in good shape with active weather day anticipated. 


Most areas will see scattered thunderstorms today...but focus will 
be on eastern counties where low level moisture and wind shear 
profiles are best suited for severe weather. Surface dewpoints 
should be into the 50s in the east with steep lapse rates and 
frontogenesis over southeast corner. Large hail and damaging winds 
will be main threats. Very heavy rain possible as well as precipitation 
water values over 1.25 inches. Steering winds should be strong 
enough to keep storms moving along...but any training echoes may 
result in flash flooding...so will be monitoring this closely 
during the day and evening. Bt 


Long term...valid for sun...Mon...Tue...Wed...Thu... 


Not much to change with the extended forecast. Models trending 
slightly warmer for the middle to late extended as more sustained 
ridge seems to be developing over the central Great Plains by 
late in the period. This forces a more amplified trough off the 
West Coast resulting in southwest flow aloft over the forecast 
area. Weak disturbances in the southwest flow aloft will bring 
periodic chances for thunderstorms through the period...with the 
best chances during the afternoon and evening hours. The only 
significant disturbance depicted in the extended is showing some 
continuity issues between the models with the European model (ecmwf) driving it 
through Tuesday afternoon and evening...while the GFS is about 12 to 
18 hours later driving it through the area. As a result have kept 
broadbrush approach to probability of precipitation in place and increased chances just a 
bit for the Tuesday through Wednesday time frame. 


Temperatures look warmest on Monday as ridge quickly pushes north 
in the wake of exiting upper trough. Middle to upper 90s seem 
reasonable for central sections with lower 90s elsewhere on 
Monday. Slightly cooler temperatures for Tuesday through Thursday 
as heights fall aloft just a bit. Will still be looking at upper 
80s to lower 90s through Thursday...slightly above normal for this 
time of year. By Friday heights aloft increase once again for 
temperatures back into the middle 90s. Some hint that if southeast 
flow aloft remains consistent through the week that some 
monsoonal moisture from Arizona and Utah could get into the area 
by Thursday into Friday which could take the edge off of 
temperatures if it comes to fruition. Chambers 


&& 


Aviation... 


A disturbance crossing the area this morning will bring scattered 
showers and thunderstorms to the area mainly north and east of 
kbil. Local MVFR conditions are possible with heaviest showers 
this morning in moderate rain. The disturbance should shift 
eastward and out of the area by early afternoon. Another 
disturbance this afternoon will produce more widespread 
thunderstorm activity. Some severe storms are possible east of a 
Red Lodge to Roundup line this afternoon...with large hail the 
main threat. MVFR conditions are expected in heavy rain with any 
storms...with IFR conditions possible with the strongest storms. 
Outside of storms VFR conditions will prevail through tonight. 
Solum 


&& 


Preliminary point temp/pops... 


Today Sat sun Monday Tuesday Wednesday Thursday 
------------------------------------------------------- 
bil 086 059/086 056/091 060/096 062/091 062/092 062/092 
4/T 30/u 00/u 02/T 22/T 22/T 22/T 
lvm 082 047/086 047/090 050/091 050/087 053/088 051/090 
3/T 20/u 00/u 02/T 22/T 22/T 22/T 
hdn 087 058/087 056/093 060/099 061/093 061/093 060/095 
4/T 30/u 01/u 12/T 22/T 22/T 12/T 
mls 088 060/086 058/091 064/095 064/091 064/092 063/095 
4/T 53/T 22/T 22/T 22/T 22/T 00/u 
4bq 086 059/086 057/091 062/094 062/090 062/092 062/093 
4/T 63/T 22/T 22/T 22/T 22/T 00/u 
bhk 084 056/084 056/088 058/090 060/088 059/086 059/091 
4/T 63/T 22/T 22/T 22/T 22/T 00/u 
shr 082 053/084 053/087 056/094 056/085 056/088 056/090 
4/T 32/T 02/T 22/T 22/T 22/T 22/T 


&& 


Byz watches/warnings/advisories... 
Montana...none. 
Wyoming...none. 


&& 


$$ 
Weather.Gov/Billings