Scientific Forecaster Discussion

Return to Local Conditions & Forecast

Without Abbreviations
With Abbreviations

Area forecast discussion 
National Weather Service Billings Montana
403 am MDT Tuesday Sep 30 2014

Short term...valid for today and Wednesday...

Pesky upper low that has been over the central rockies the past
36 hours is slowly moving northeast and will be over western South
Dakota by this afternoon. At the same time...a surface low over
northeast Colorado will move north and also be across western
South Dakota by this afternoon. Models are in good agreement with
these stacked lows which will result in a rainy day across far
southeast Montana. Rapid City radar showing numerous showers with
embedded thunderstorms rotating counter-clockwise around the
surface low and moving north/northwest across northeast
Wyoming...western South Dakota and into far southeast Montana.
This precipitation will continue to move north and west during the day
and mainly impact the eastern half of Powder River and Custer
counties and all of Fallon and Carter counties. The rain will be
moderate to heavy at times with the highest precipitation amounts across
Fallon and Carter counties. Models continue to place an additional
1-1.5 inches of rainfall across Fallon and Carter counties today
into this evening. In addition...the surface low will strengthen
today resulting in tightly packed isobars across Fallon and
especially Carter counties today allowing for gusty northwest
winds this afternoon. Elsewhere across the forecast area...just a
chance for a scattered shower exists along with an isolated
thunderstorm. Temperatures will be similar to yesterday's or just
a few degrees warmer across our central and western
locations...but cooler readings can be expected across the east as
a result of thicker cloud cover and rain.

Both lows eject northeast into North Dakota tonight taking the
bulk of the rain with them. Rain chances will slowly diminish
across the east during the evening into the overnight hours with
just a chance for a shower across the forecast area after
midnight. An unsettled northwest flow aloft will be over the
forecast area Wednesday. A disturbance within the flow along with
another cold front will move across the area Wednesday morning
bringing slightly higher shower chances mainly to the mountains
and upslope foothills locations. High temperatures will be a few
degrees cooler than today for most areas with readings only
getting into the upper 50s to around 60 degrees. Hooley

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

Strong jet moving across the forecast area on Thursday and will
drive a short wave trough and associated cold front southward out
of Alberta. The jet will bring moderate q vector forcing along
with strong jet divergence. Moisture does look limited at this
time and down slope surface winds will be over the region to limit
precipitation chances to isolated to scattered. Dry weather and
warmer temperatures will return on Friday and continued through
next Tuesday as a ridge of high pressure builds in over the area.
Below normal temperatures are expected on Thursday but will warm
to near seasonal on Friday and above normal over the weekend
through the first part of next week. Richmond



IFR to LIFR conditions are expected across portions of south
central and southeast Montana this morning with areas of fog. The
fog will be along and east of a line from Sheridan to Billings to
Miles City. The fog is expected to dissipate by 16z. Showers and a
few isolated thunderstorms will continue to move into southeast
Montana this morning. Rainfall is expected to be heavy and will
create IFR to LIFR conditions throughout the day. The heaviest
rainfall will be located just east of a line from Miles City to
Broadus. Richmond


Preliminary point temp/pops...

Today Wednesday Thursday Friday Sat sun Monday
bil 065 044/059 040/057 036/068 049/073 049/071 047/069
2/T 22/west 12/west 00/u 00/u 11/u 10/u
lvm 064 039/056 035/058 034/068 042/071 042/068 041/068
3/T 32/west 12/west 00/u 00/u 11/u 10/u
hdn 067 043/061 039/059 034/069 045/074 046/072 044/070
2/T 22/west 12/west 10/u 00/u 11/u 10/u
mls 064 047/060 041/057 031/065 045/073 046/069 044/067
7/T 32/west 12/west 00/u 00/north 11/u 10/b
4bq 059 044/060 039/059 031/065 044/072 046/069 043/067
8/T 32/west 12/west 20/u 00/north 11/u 10/u
bhk 059 045/059 038/056 030/058 039/068 043/065 041/062
+/T 73/west 12/west 10/u 00/u 11/u 10/b
shr 064 044/057 036/059 032/067 041/071 044/068 040/068
2/T 42/west 12/west 20/u 00/u 11/u 10/u


Byz watches/warnings/advisories...



National Weather Service Glossary of Abbreviations