Scientific Forecaster Discussion

Return to Local Conditions & Forecast

Without Abbreviations
With Abbreviations

Area forecast discussion 
National Weather Service Billings Montana
327 PM MDT Tuesday Aug 4 2015

Short term...valid for Wednesday and Thursday...

Negatively tilted trough regime continues this evening over the
area. One upper low is south of the area with a second weaker
impulse to the west. Low over Wyoming will continue to push low
and middle level moisture into eastern zones this evening keeping
likely precipitation chances in place as a cold front pushes
through the area. Second low off to the west will bring a few
additional storms to western areas through late evening. With
cloud cover and showers dropping afternoon temperatures into the
upper 60s to lower 70s think potential for stronger storms/heavy
rain has faded west of a Hysham to Ashland line and pulled mention
from the forecast. Latest high-res models stall the frontal
progression along a Miles City to Broadus line around midnight. If
this occurs will keep at least scattered showers in the forecast
overnight over this area...but areas from Baker to Alzada would
see less precipitation. No changes to the going Flash Flood Watch
for tonight as any storms in this area will produce very heavy
rain over a short period of time and may lead to flash flooding.

Another good chance for thunderstorms arrives tomorrow as a
disturbance currently over California/Nevada pushes into the area
by middle day. Forecast shear/cape supportive of a few strong storms
developing over western areas by middle day...shifting into the east
by evening. Precipitable water values are once again well above
normal tomorrow. But unlike today storms on Wednesday should be
moving pretty quickly thanks to stronger middle level southwesterly
flow so threat of flash flooding will be much less. Temperatures
will be back in the middle to upper 80s for most locations Wednesday
afternoon...with more sun than today.

North Pacific system will push inland on Wednesday and cross
northern Montana on Thursday. Latest model consensus with
position to the north of the forecast area puts US on the dry and
windy side of the system. However there are a few model members
that have the system just a bit further south than operational
consensus leading to a better chance of precipitation and cooler
temperatures. Currently leaning on a drier and breezy forecast for
Thursday with downslope winds in place. If the system shift just a
100 miles further south will Need More precipitation for Thursday
along with going about 10 degrees cooler on temperatures.
So...will be looking at this closely the next 24 hours. Chambers

Long term...valid for Friday...Sat...sun...Mon...Tue...

Not many changes needed to the long term discussion from this
morning. Most of the changes dealt with the fine-tuning of
precipitation chances and increasing temperatures during the
beginning of next week.

Long term period will start off with a shortwave approaching from
the southwest. Looks like any significant rain chances will hold
off until Saturday as we will be under shortwave ridging.
Temperatures will not be too warm on Friday and Saturday as heights will
still be fairly low thanks to an upper level low to our north.
Expecting near seasonal temperatures in the middle to upper 80s.

Shortwave moves through the region early Sunday afternoon giving
most locations a chance for showers and thunderstorm with eastern
locations seeing the better chances for rain later in the
afternoon. For Monday a digging trough off the Washington coast
will quickly increase heights and begin another warm up. By the
end of the period on Tuesday upper 90s are possible but only went
with low to middle 90s until we get some model consistency. Dobbs



Two areas of showers will affect area terminals this evening
before things clear out after 06z. One area to the east is affecting
kmls. Gusty winds and thunderstorms in the vicinity is possible through 03 as these storms
move slowly NE. Another area of showers and isolated storms are
just east of lvm and moving east-northeast. These could give kbil and kshr
thunderstorms in the vicinity around 23-02z. After sunset expect mostly vcsh at all
terminals until 06-07z. Winds should become mostly westerly after
06z tonight with VFR conditions prevailing for the remainder of
the period. Dobbs


Preliminary point temp/pops...

Wednesday Thursday Friday Sat sun Monday Tuesday
bil 061/085 059/085 056/083 057/084 058/082 058/091 059/093
34/T 41/north 11/u 13/T 32/T 21/u 11/b
lvm 055/077 050/080 046/083 050/081 052/081 052/088 052/089
34/T 41/north 11/u 14/T 44/T 22/T 11/b
hdn 060/088 060/087 056/085 055/087 057/084 057/093 057/095
44/T 41/north 11/u 13/T 33/T 21/u 11/b
mls 062/089 064/085 058/084 057/085 060/082 060/089 061/092
72/T 42/T 11/b 13/T 33/T 31/u 11/b
4bq 061/089 061/085 057/083 057/085 058/082 058/090 059/092
73/T 41/b 11/b 13/T 44/T 31/b 11/b
bhk 062/086 062/081 056/082 053/082 057/079 056/085 057/089
52/T 53/T 11/b 13/T 44/T 42/T 11/b
shr 057/085 057/083 053/083 053/085 054/082 053/089 053/090
43/T 41/b 11/u 13/T 32/T 21/u 11/b


Byz watches/warnings/advisories...
Montana...Flash Flood Watch in effect until midnight MDT tonight for
zones 31>33-36-37-58.



National Weather Service Glossary of Abbreviations