Scientific Forecaster Discussion

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Area forecast discussion...updated 
National Weather Service Billings Montana
954 am MDT Wednesday Apr 23 2014


Strong Pacific front has worked its way east of the state and has
taken the bulk of the precipitation with it. Radar still showing some
lingering showers across our eastern zones and these will move out
later this morning. However...there still remains a slight shower
chance across the forecast area today. Strong subsidence behind
the front will allow for a blustery day with winds gusting in the
40 to 50 miles per hour range at times...especially across open areas.
Temperatures will be much cooler today with highs only in the 40s
across the far western areas to upper 50s near the Dakota borders.
Forecast has this all handled well so no updates are planned.


Short term...valid for today and Thursday...

Upper level system with a slow eastward progression is centered
over western Montana this morning. At the surface a cold front
has moved into central areas...just east of Billings...and will
push through southeast Montana by middle morning. Shower and thunderstorm
activity has been greatest to the north of the area overnight
despite strong dynamic lift. Instability combined with downslope
winds are responsible for suppressing convection...though there
are still a few areas of shower activity near the front as well as
over western mountains and valleys. Gusty west to northwest flow
will continue to dry out the atmosphere today which will limit
shower activity once the cold front has pushed east of the area.
As a result have trended probability of precipitation lower today. Strong mixing today
will allow stronger winds aloft to work to the surface and expect
gusts of 30 to 50 miles per hour to be common into this evening. Guidance
suggests a chance of gusts over 50 miles per hour from Livingston to Big
Timber today but direction will be westerly which will limit
crosswind exposure along I-90. Temperatures will stay in the 50s
across the region today...with 30s in the mountains.

A disturbance currently over western Canada will slide southeast
and across the area tonight. Moisture will be limited over the
lower elevations but can't rule out a light rain/snow shower as it
passes so kept low probability of precipitation in place. There is a better chance for
some light snow accumulation over mountain locations...especially
in the Big Horn Mountains. Temperatures tonight will drop into the
30s...with a few upper 20s over western valleys.

Thursday will be breezy but less windy than today. With continued
unstable northwest flow can't rule out a few light showers but no
significant precipitation is expected. Temperatures will climb a
few degrees warmer than today with Thursday highs in the lower
60s. Southwesterly flow aloft builds into the area Thursday night
with a chance of rain/snow showers over western mountains and
valleys. Low temperatures will be in the 30s. Chambers

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

Next system to impact the region moves into the Pacific northwest
on Friday and tracks across the northern Great Basin Saturday
before developing a strong storm system in the Lee of the Colorado
rockies. Friday is a day in between systems and mainly dry with
temperatures rebounding into the 60s.

By Saturday temperatures fall and moisture increases as low level
flow becomes upslope. One of the subtleties in the forecast is how
quickly the airmass moistens in response to a subtropical plume
getting entrained into the system. Models are in good agreement
of the position of the upper low by Sunday but they are differing
on how cool and how deep the moisture remains over southern
Montana and north central Wyoming on Sunday. Opted for no changes
since European model (ecmwf) supports the current cooler solution but GFS tries to
be warmer and produce a bit less precipitation. Will let next
shift take another look before beginning to warm up temperatures.

Break in the weather starts on Monday though precipitation may
hang into southeast Montana for part of the day. Tuesday and
Wednesday look drier and warmer. Borsum



Gusty west to northwest surface winds will affect the area today with gusts
to 30 to 40 knots. Otherwise expect isolated to scattered rain and
snow showers this morning changing to all rain showers this
afternoon. MVFR conditions east of kbil will become VFR this
afternoon. However...MVFR to IFR conditions will be possible with
the showers across the area. An isolated thunderstorm will also
be possible this afternoon. Isolated to scattered rain and snow
showers will continue tonight. Expect areas of obscuration over
the mountains through tonight with widespread obscuration over
the beartooths and absarokas. Winds will diminish somewhat
tonight. Arthur

Preliminary point temp/pops...

Today Thursday Friday Sat sun Monday Tuesday
bil 054 036/060 039/062 039/052 039/044 032/052 038/061
2/west 32/west 22/west 44/west 66/west 32/west 22/west
lvm 047 034/054 033/063 035/052 038/050 030/056 034/066
3/west 32/west 23/west 46/west 66/west 32/west 23/west
hdn 056 036/061 038/063 037/058 037/046 031/052 034/062
2/west 32/west 22/west 44/west 66/west 42/west 21/b
mls 059 037/060 038/059 037/047 037/042 029/049 030/053
3/west 22/west 11/b 66/west 77/west 74/west 21/b
4bq 058 034/059 037/058 034/054 036/047 029/050 030/053
3/west 31/north 11/b 44/west 77/west 63/west 31/b
bhk 058 034/056 036/058 033/045 032/039 026/045 027/050
3/west 22/west 11/b 46/west 67/west 74/west 21/b
shr 052 031/057 034/065 038/062 040/047 033/051 034/057
2/west 22/west 22/west 33/west 66/west 43/west 22/west


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