Area Forecast Discussion
Issued by NWS Billings, MT

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FXUS65 KBYZ 261517
AFDBYZ

Area Forecast Discussion...Updated
National Weather Service Billings MT
917 AM MDT THU MAY 26 2016

.UPDATE...

Forecast looks to be in good shape with only a few minor tweaks
with this mornings update. An upper low continues to be located
over Northeast Montana this morning and will slowly shift
east/southeast today. Satellite showing quite a bit of clear skies
from Treasure County to Carter County so I did adjust sky cover to
reflect more sun this morning for these areas. However, with cold
air aloft associated with this upper low, I expect these clearing
areas to fill in with clouds by early afternoon. However, there
will still be breaks of sun across the forecast area today.

Radar is showing some shower activity across Big Horn and
Sheridan Counties, as well as across the northeast portions of the
state associated with the upper low. Overall, look for scattered
showers and isolated thundestorms today. Freezing levels remain
low so about any thunderstorm will most likely produce some pea
size hail or possibly slightly larger, but widespread
strong/severe weather is not expected today. Updated forecast has
been sent. Hooley

&&

.SHORT TERM...valid for Tdy and Fri...

Last evenings thunderstorms were stronger than expected...even
though most of the hail reported was only about a half inch. Post
analysis showed several outflow boundaries floating about the area
from late afternoon convection. These eventually collided just
north of Billings and lead to some rapid development due to steep
lapse rates thanks to the cold mid level temps aloft (related to
the upper low over us). Billings Heights and nearby locations thus
ended up with some strong convection and plenty of hail...with one
report of quarter size a couple of miles northeast of the city.

That upper low will again be the primary driver for the short term
forecast. Models show it gradually wobbling to a position a little
further east than yesterday...generally placing it over the
Montana/Dakota border. So it would appear associated vorticity
forcing will be best further east than last night. We will look
for the stronger storms to be over our east today...with the
largest population affected around Miles City. We will still carry
scattered thunderstorms elsewhere simply due to the cyclonic flow
and instability, and the possibility of colliding boundaries once
again.

Friday will see another actively convective day. The upper low
will have finally merged with the broader trough axis to the south
and moved into the Dakotas, but leaves our east in a deformation
zone. This should result in scattered convection along our
furthest east zones such as Fallon, Custer and Carter counties. In
the meantime, another progressive upper low will slide into the
northern Rockies from British Columbia aiding convective
development over the Montana high country. So some activity over
the Beartooths and nearby areas is also expected...though the
stronger convection here may be northwest of our CWA.

Look for highs today to remain seasonal, and then a bit warmer
for Friday. BT

.LONG TERM...valid for Sat...Sun...Mon...Tue...Wed...

Several relatively minor changes to the extended forecast period
this morning. The broad upper level trof keeps the region in a
generally unsettled and mild pattern through the period, with
models in reasonably good agreement.

The upper low will slowly east east through Wednesday, with
shortwaves rotating through the area. Raised pops for two more
significant waves progged through the region Saturday and Monday
into Tuesday. The best potential for stronger storms will also
accompany these waves...especially for the Monday wave in the
East. Also increased Wednesday pops...as main trof axis is progged
across the region.

Models prog a ridge to build over the west starting late
Wednesday into Thursday, potentially bringing drier weather to the
region. Temps will continue to run near to slightly below normal.
Gilstad

&&

.AVIATION...

Isolated to scattered showers and a few thunderstorms will be
accompanied by MVFR conditions this morning. Expect localized
mountain obscurations. Chances for thunderstorms will increase
this afternoon and continue this evening. Some storms will be
accompanied by small hail and wind gusts to 45 kt. MVFR/IFR
conditions will accompany the thunderstorms...along with areas of
mountain obscuration. A few showers will linger over the
mountains and E of KBIL overnight through Fri. morning with
localized mountain obscurations. Arthur

&&

.PRELIMINARY POINT TEMP/POPS...

    Tdy Fri     Sat     Sun     Mon     Tue     Wed
-------------------------------------------------------
BIL 067 046/070 047/067 046/072 048/069 046/065 044/068
    4/T 33/T    54/T    32/T    34/T    44/T    43/T
LVM 066 041/065 040/062 040/067 041/066 041/062 040/067
    4/T 35/T    64/T    32/T    34/T    44/T    32/T
HDN 069 043/073 047/070 045/074 048/073 047/066 043/069
    3/T 23/T    34/T    32/T    34/T    55/T    43/T
MLS 066 048/073 051/072 049/076 051/075 051/068 047/068
    4/T 32/T    24/T    32/T    44/T    55/T    55/T
4BQ 069 044/073 046/071 045/075 048/075 047/068 044/069
    4/T 22/T    25/T    32/T    44/T    55/T    44/T
BHK 066 043/071 045/071 045/074 046/073 047/068 044/067
    5/T 33/T    15/T    32/T    44/T    55/T    44/T
SHR 066 040/070 043/067 041/073 043/071 043/065 041/067
    3/T 22/T    24/T    43/T    34/T    44/T    43/T

&&

.BYZ WATCHES/WARNINGS/ADVISORIES...
MT...None.
WY...None.

&&

$$
weather.gov/billings



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