Area Forecast Discussion
Issued by NWS Billings, MT

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FXUS65 KBYZ 190248

Area Forecast Discussion...Updated
National Weather Service Billings MT
848 PM MDT Sat Mar 18 2017

Winds have briefly hit advisory level criteria in Livingston and
Nye, but are expected to gradually decrease the next few hours as
latest analysis indicates pressure rises over south central
Montana. Thus we will forego any highlight at this point.
Showers are still expected to move in late tonight and develop
eastward over the plains Sunday. Rain showers look like a good bet
tomorrow afternoon as cross sections indicate strong jet dynamics
creating sharp ageostrophic forcing and mid level moisture
saturation. This may start out as scattered showers in the morning
and then develop into a narrow band of precipitation that slowly
shifts south by evening. Nudged some PoP`s up for tomorrow
afternoon based on these progged cross sections we are seeing. BT


.SHORT TERM...valid for Sun and Mon...

Previous forecast was in good shape. Did make some changes to
trend with the latest models. At 19z, cold front was seen in
surface observations moving through central WA and OR.
Precipitable waters ahead of the front were on the order of
/0.8-0.9/ inches. This moisture will decrease as the front crosses
the mountains this evening. Will still have enough moisture to
fuel precipitation for the next couple of days. PoPs will be
confined to the far western high elevations this evening. Moisture
will increase further overnight, bringing the likelihood of
rain/snow showers to the SW mountains, with slight chances over
KLVM and the Crazys. Continued gusty winds in the KLVM/Nye areas
until the frontal passage, and will keep the wind table going for
travelers on I-90.

Cold advection will be over the area on Sunday as the front sinks
S. Low chances for morning precipitation will increase in the
afternoon due to increasing frontogenesis and easterly upslope
flow. The best chances for precipitation will continue over the
SW mountains due to deep moisture. Expect high temperatures in the
50s to lower 60s on Sunday. Cold advection continues Sun. night
and the front will stall out over the southern zones. Best chances
for precipitation will remain over and near the mountains with
east upslope flow. Expect scattered rain and snow showers over the
plains. Any snow accumulations will be light due to the relatively
warm airmass and low QPF. The front remains stationary on Monday
with easterly upslope flow. Thus upslope areas will have higher
PoPs than other areas. Temperatures will be in the 40s which is
normal for this time of year. Again, any snow accumulations will
be light.

ESE flow strengthens Mon. night, bringing in more moisture from
the SE. Precipitation chances along the front will thus increase
to the high chance/likely category. It will be a colder night with
850 mb temperatures below zero degrees c. Rain/snow showers will
turn to all snow overnight. Accumulations still looked
light...with around an inch in some low elevation 2
inches in the mountains. Arthur

.LONG TERM...valid for Tue...Wed...Thu...Fri...Sat...

Unsettled pattern continues over the region through the extended,
but best chances for precipitation will stay mainly south of the
area as models continue to dig pacific trof over the western U.S..
Best day for precipitation of a light nature will be Tuesday as
deep upslope easterly flow develops, providing upslope
enhancement. However the main forcing will stay south of the area,
so just a glancing blow for N WY/S MT. Could be a little bit of
light snow accumulation for the morning hours. Highs Tuesday look
to be mainly in the 40s.

That system shifts east on Wednesday with deep southwesterly flow
moving into the area providing a boost in temperatures (60s) and
lesser precipitation chances.

Another deep trof begins to impact the area on Thursday but once
again the main focus of this system will be the southern Rockies.
Diffluent southwest flow though will keep a chance of showers in
the forecast headed into the weekend with temperatures in the 50s.
Yet another Pacific system moves into the area Saturday night into
Sunday, and this one looks to be further north and may provide a
better shot at precipitation for the area. Chambers


VFR conditions will prevail overnight, but mountain peaks may
become obscured late. Frontal system will move through late
tonight with scattered showers developing from west to east into
Sunday. Some areas of MVFR are possible with shower activity
tomorrow. Expect some areas of strong winds (25 to 40kts) around
KLVM until about 05z. Across the plains low level wind shear is
likely at more sheltered airports. BT


    Sun     Mon     Tue     Wed     Thu     Fri     Sat
BIL 047/057 033/045 032/050 036/064 040/055 035/057 034/058
    05/W    53/W    44/W    21/B    22/W    31/B    11/B
LVM 043/059 033/047 032/053 037/062 035/055 031/054 033/056
    26/W    55/W    54/W    32/W    23/W    32/W    12/W
HDN 044/060 033/049 031/054 033/066 036/056 033/058 032/060
    03/W    43/W    54/W    21/B    23/W    21/B    11/B
MLS 044/059 033/051 031/046 033/062 037/055 034/054 032/056
    03/W    32/W    34/J    32/W    22/W    21/B    00/B
4BQ 044/062 033/049 030/047 031/063 036/055 033/055 032/059
    02/W    32/W    64/J    31/B    23/W    21/B    00/B
BHK 040/057 030/050 025/041 028/056 034/052 030/051 030/051
    01/N    31/E    35/J    32/W    22/W    20/B    00/B
SHR 044/062 032/050 032/055 034/064 037/054 033/055 031/060
    12/W    24/W    43/W    21/B    23/W    31/B    11/B




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