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Area forecast discussion...updated 
National Weather Service Billings Montana
838 PM MDT sun may 3 2015

dewpoints increasing along the Montana Wyoming border as low level easterly
flow lines up with exit region of the jet. Increased chances of
precipitation for southern Carter and Powder River counties as a
wedge of cooler air is helping create lower dewpoint depressions
and will give that area a better chance of seeing moisture reach
the ground. Borsum


Short term...valid for Monday and Tuesday...

Sprinkles were gradually exiting southeast Montana per radar imagery/webcams
this afternoon. Starting to see echoes just S of Montana/Wyoming border over
the absarokas. Departing upper jet will keep some lift from the
right-rear quadrant over the area tonight...along with weak
shortwaves and weak isentropic lift. Kept probability of precipitation for showers across
the S this evening with highest probability of precipitation in mountains. Dried out the
SW overnight.

Weak ridging and rising heights will be over the area on Monday with
continued weak isentropic lift. A low-level jet will also develop
over the area. Sref had surface convective available potential energy over 500 j/kg from kbil to
the NE bighorns west Monday afternoon...but lack of decent lift and
moisture will keep thunderstorm development confined to mainly the
mountains. Some of the storms could be strong due to the high
cape. Shear...however...was weak. Monday will be warmer than today
with mixing close to 700 mb where temperatures will be zero to +4
degrees c. Kept a low chance of showers with possible thunderstorms
over and near the mountains Monday evening...then dried out the area

The split Pacific system will approach the region on Tuesday with an
open wave moving through The Four Corners region and the northern
low moving through the Pacific northwest. Lowered probability of precipitation Tuesday morning...then
kept probability of precipitation from kbil to kshr west Tuesday afternoon as surface convergence
develops over this area ahead of the system/S cold front.
Temperatures will climb well into the 70s to around 80 degrees in
the pre-frontal environment. The low-level jet will persist over
the region through Tuesday night...gradually increasing moisture over
the area. Convective available potential energy and shear on the sref were similar to Monday/S values
and were in the same location as Monday. However...the sref generated
higher quantitative precipitation forecast on Tuesday than Monday. The cold front will approach the area
from the west Tuesday evening. Lowered probability of precipitation over the east as moisture will
take time to increase out ahead of the front. Had better chances
for precipitation late Tuesday night as the front pushes into the area
and precipitable waters climb to a half inch west to an inch in the
southeast. Arthur

Long term...valid for Wednesday...Thu...Fri...Sat...sun...

Medium range guidance continues in fairly good agreement with an
unsettled pattern later this week and into next weekend. An upper
low will dig along the West Coast and then lift northeast out of
the Great Basin and into the northern rockies by next weekend.
Initially an upper level southwest flow will prevail with a series
of disturbances lifting across our area helping to enhance
precipitation at times. Timing of these waves is the main
challenge for Wednesday into Friday. Then...upper low expected to
lift northeast across Wyoming and into the Dakotas by late in the
weekend. This path would be ideal for widespread wrap around
moisture and deeper upslope. Something else to watch...the latest
GFS advertising colder temperatures with the potential for even
lower elevation snow across northern Wyoming and southeast Montana on Sunday.
The overall theme will continue to be periods of wet weather from
Wednesday all the way to next Sunday. Right now...nothing appears
to be a high impact given the dry conditions we have in
place...but will need to be monitored over the coming days
especially if snow starts to become a factor. As for
temperatures...Wednesday setting up as our warmest day...with near
seasonal temperatures. More clouds and precipitation will keep
temperatures below normal into next weekend. Frieders



Most of the area will see VFR conditions prevail into Monday
morning. Some showers will move over and near the
mountains...including kshr and extreme southern Carter and Powder
River counties. Anticipate some mountain obscurations.


Preliminary point temp/pops...

Monday Tuesday Wednesday Thursday Friday Sat sun
bil 045/074 048/077 048/065 045/051 040/053 041/056 040/059
11/b 12/T 34/T 35/west 43/west 56/west 54/west
lvm 038/073 042/075 042/062 039/047 035/049 036/052 035/062
12/T 23/T 55/T 46/west 44/west 56/west 54/west
hdn 044/076 045/080 048/067 044/054 040/056 040/062 037/060
21/b 11/b 33/T 34/west 33/west 46/west 53/west
mls 045/069 047/076 049/067 044/059 041/060 042/059 039/056
11/north 11/b 34/T 33/west 22/west 34/west 54/west
4bq 045/065 044/073 049/066 045/059 042/056 040/058 038/054
43/west 11/b 45/T 33/west 33/west 45/west 55/west
bhk 040/062 041/069 047/064 043/058 038/057 038/054 038/053
12/west 01/north 46/T 33/west 22/west 34/west 55/west
shr 042/069 042/072 045/063 041/054 038/055 039/056 036/056
41/b 12/T 44/T 34/west 44/west 56/west 54/west


Byz watches/warnings/advisories...



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