Scientific Forecaster Discussion

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Area forecast discussion 
National Weather Service Billings Montana
314 PM MDT Sat Apr 19 2014

Short term...valid for sun and Monday...

Minimal minor tweaks to going short term forecast...as all
appears to be in good shape for the weekend and early next week.
Quiet and warm weekend weather can be expected to continue through
Monday.

Ridging and dry air under upper level ridging prevail across the
region today. Another upper level trough slides east along the
Canadian/Montana border on Sunday. The front will move through the
region...slightly cooler air and gusty winds back to the region.
The best energy...however...remains north of the County Warning Area and the
airmass continues to appear quite dry. So expect no precipitation or
thunderstorm concerns from this system. This system moves pretty
quickly through the region Sunday...with another period of upper
level ridging to bring warm and dry conditions to region again for
Monday.

Expect to see increased mountain snowmelt over the next several
days...especially at middle level elevations. We do not expect there
to be any flooding issues...but stream flows and river levels will
be on the rise. Aag

Long term...valid for Tuesday...Wed...Thu...Fri...Sat...

Models continuing to come together in showing cooler and
unsettled weather for midweek...but without the significant precipitation
event that could have had hydrologic implications for our region.

Tuesday should be the warmest day of the extended with thermal low
in southeast Montana under amplified SW flow aloft. Have tweaked up temperatures a
bit more to show highs further into the 70s...quite likely the
warmest day yet of 2014...and it is possible some areas could
approach 80f with enough mixing. This is supported by tongue of
700mb temperatures to +8c into Sheridan County. In addition...combination
of modest moisture advection out of the southeast...height falls and
diurnal destabilizing will result in a fair chance of thunderstorm
activity Tuesday aftn/evng. Do not see enough low level moisture
for storms to get too strong...but it does look to be the most
interesting convective potential we have seen yet this Spring.

Greatest chance of precipitation Tuesday night will be in our west along
middle level baroclinic zone as shortwave lifts out of the SW. Snow
levels will fall rapidly in our west behind the middle level
front...so expect rain to accumulating snow over the beartooth
absaroka and Crazy Mountains late Tuesday night. Focus of precipitation will
shift east on Wednesday...with good model consensus in showing a
transition to stronger low level downsloping in our west as middle
level trough lifts to our north. Overall this is shaping up to be a
period of showers rather than a long duration precipitation event.

Next trend that exists among all models today is for the middle
level low to shift to our NE into Thursday. This should allow for
at least a chance of precipitation and cooler air to slide into our east
Thursday/Thursday night...but with an overall trend toward drier
solutions and a weaker trowal today. Have begun to scale back probability of precipitation
across the area from Wednesday night through Thursday night...
keeping highest probabilities in our east and over the mountains with
downsloping expected for our western lower elevations. In fact...
biggest impact in the Wednesday/Thursday period may end up being
wind...ie should see fairly strong west-northwest winds these days
especially during peak mixing times. Have also trended wind speeds
up on these days. For the mountains...any precipitation that falls will be in
the form of snow...so we are not looking for much snow melt in the
high country once we get past the mild Tuesday.

Obviously models are still trying to get a handle on the middle week
system so forecast confidence by the end of the week is even
lower. GFS/ECMWF/UKMET/Canadian all suggest more Pacific energy of
some sort by Friday/Saturday so will keep with broadbrushed near
climatology probability of precipitation for these days. Consensus is to keep a positive height
anomaly in northwest Canada...and this would certainly keep our weather
pattern active with lower than normal heights expected for the
Pacific northwest and northern rockies.

As for temperatures...after a very mild Tuesday we will see
cooler temperatures for Wednesday and Thursday but perhaps not as cool as
we previously thought. Expect some moderation for Friday and
Saturday...and have stayed near climatology on these days.

Jkl
&&

Aviation...

VFR conditions will prevail across the region through Sunday.
Wind gusts will approach 30 kts at klvm this afternoon and
tonight. A mainly dry Pacific cold front will move through the
area early Sunday morning...bringing a shift of winds from the
S-SW to W-NW...and gusts of 20-30 kts across the area through the
day. Jkl

&&

Preliminary point temp/pops...

Sun Monday Tuesday Wednesday Thursday Friday Sat
-----------------------------------------------------------
bil 043/067 039/069 044/074 046/057 037/057 035/060 039/062
01/north 00/u 12/T 45/west 33/west 22/west 22/west
lvm 039/063 038/070 041/072 039/053 033/059 034/063 037/062
11/u 00/b 26/T 76/west 33/west 22/west 22/west
hdn 038/069 035/070 039/077 041/058 034/055 032/060 035/063
01/u 00/u 12/T 35/T 44/west 22/west 22/west
mls 038/068 035/067 040/073 045/061 037/053 031/054 034/061
01/north 00/u 01/b 35/T 34/west 31/b 22/west
4bq 039/070 035/069 042/077 045/062 034/054 031/056 033/063
01/north 00/u 02/T 26/T 44/west 31/b 22/west
bhk 036/067 034/065 039/069 046/063 036/050 028/051 030/057
01/north 00/u 00/north 35/T 34/west 31/east 22/west
shr 038/067 035/069 039/077 043/058 037/054 032/060 036/066
01/u 00/u 02/T 26/T 43/west 22/west 22/west

&&

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

&&

$$
Weather.Gov/Billings