Area Forecast Discussion
Issued by NWS Billings, MT

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FXUS65 KBYZ 190256

Area Forecast Discussion...Updated
National Weather Service Billings MT
856 PM MDT WED MAY 18 2016

Isolated showers and a stray lightning strike possible north of
Billings for a few more hours as weak convective activity persists
due to diurnal instability. Airmass will be stabilizing after
midnight with activity ending. Updated forecast to expand this
activity further east as it is making its way from Musselshell
county into Rosebud and Treasure and another weaker set of showers
has developed to the west of this band.

Looking ahead to the convective potential the next days will be
watching the convective outlooks at to
see if they are any changes.



.SHORT TERM...valid for Thu and Fri...

Only made a few minor changes this afternoon...with models
remaining in good agreement for potential for afternoon and
evening thunderstorms through the period.

Cu are developing well over high terrain this
potential remains good for isold to sct temperatures
climb into mid 70s. Best chances reamin in west most zones...but
cannot completely rule diminishing activity as far east as

Thursday and Friday have much more significant potential for
strong to severe thunderstorms. A deep trof settles over the
Pacific NW, bringing increasing SW flow aloft over our area.
Western most zones again appear to be best location for convection
each day. Baroclinicity will combine upper level jet support to
create unstable environment, but a cold front will increase chance
of showers and tstms. Capes on the order of 500-1000 j/kg are
progged each day. Shear is not extremely strong...may be
sufficient for a few strong to severe storms, especially in high
terrain...and around Livingston and Harlowton. The only real
limiting factor is lack of moisture, and significantly reduced
instability as proceed east. Therefore...activity should become
weaker as it moves east during the evening.

Cold front will stall Thursday night, and activity will taper off
overnight. Friday looks much the same, although with a bit better
moisture availability in the west from Thursday precip. The best
potential for strong to severe storms slips a bit further east,
and into the Billings area. Diminishing showers and thunderstorms
as far east as Forsyth...and approaching Miles City.

Will continue to message the potential for stronger thunderstorms,
and an overall increase in thunderstorm activity of which we have
not seen yet this spring, in our weather story and through social
media. Gilstad

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

MAde only minor tweaking to the extended forecast period, as
models remain in good agreement for generally mild unsettled
weather over the weekend and early next week.

The surface low shifts north on Friday night, bringing warmer and
drier conditions to the area from Wyoming on Saturday. Some
thunderstorms are possible, especially in eastern most and
western most zones, but conditions do not look favorable at this
time for strong or severe storms. Additionally, a well mixed
boundary layer should keep most convection out of the plains.

The upper level low pushes slowly eastward by the end of the
weekend, and remains in place through the remainder of the period.
This airmass is cooler and generally unsettled...keeping showers
in place each day...and isolated thunder each afternoon/evening.
Did trend temps up slightly...but should be a few degrees below
average...with highs in the upper 60s to low 70s. Gilstad



Some light showers and isolated thunderstorms were found across
the area this evening, from Musselshell County westward, with the
thunderstorm activity focused across the north as of 02Z. The shower
and thunderstorm activity should gradually diminish over the next
few hours as we lose the daytime heating. VFR conditions should
then continue into the overnight hours. STP



    Thu     Fri     Sat     Sun     Mon     Tue     Wed
BIL 050/081 050/076 051/079 050/068 046/066 046/069 046/071
    12/T    53/T    33/T    33/T    34/T    43/T    33/T
LVM 043/073 043/068 043/069 041/063 039/061 039/065 039/065
    36/T    55/T    43/T    34/T    44/T    43/T    34/T
HDN 046/083 047/081 050/083 049/070 045/067 043/071 043/072
    11/B    32/T    22/T    23/T    45/T    53/T    33/T
MLS 050/084 054/086 058/090 055/076 049/068 047/070 047/073
    20/U    12/T    21/U    24/T    44/T    43/T    32/T
4BQ 045/083 049/087 054/089 050/076 045/067 044/070 043/071
    00/B    12/T    11/B    24/T    44/T    43/T    33/T
BHK 044/079 049/080 053/087 052/077 045/068 042/070 043/070
    00/U    02/T    11/B    35/T    54/T    43/T    33/T
SHR 042/080 045/081 048/081 046/069 042/062 041/066 040/069
    11/B    22/T    22/T    24/T    44/T    43/T    33/T




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