Area Forecast Discussion
Issued by NWS Billings, MT

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106
FXUS65 KBYZ 200938
AFDBYZ

Area Forecast Discussion
National Weather Service Billings MT
338 AM MDT Thu Jul 20 2017

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

Weak energy associated with a departing jet streak overhead may
bring an isolated shower or thunderstorm to eastern areas early
this morning. Otherwise, main story today is a shortwave
approaching from the west and an associated surface trough over
the area. The aforementioned surface trough will push east through
the day with thunderstorms developing over the higher terrain and
moving off onto the eastern plains. A few strong to severe
thunderstorms are expected on the east side of the surface trough
during the afternoon and evening hours (areas mainly east of
Rosebud County). This is confirmed with models progging MUCAPE up
to 1500 j/kg and 30 to 40 kts of deep layer shear in these areas.
Main threats will be strong gusty winds and large hail.
Thunderstorms will linger longest across the far east in the
evening, eventually moving into the Dakotas.

In addition to the thunderstorms today, gusty southwest to west
winds will develop across western and central areas, elevating
fire weather concerns. Latest models have trended stronger with
winds today, especially across northwestern and northern areas
where minimum RH values may dip into the single digits as well.
Have gone ahead and issued a Red Flag Warning from 18z today
through 03z this evening to account for very low RH values and
gusty winds.

Going into tonight, main surface front pushes through the area
causing winds to shift to the northwest overnight into early
Friday. This will be a mainly dry front with perhaps an isolated
shower or thunderstorm. Gusty post-frontal winds can be expected
for Friday with mostly dry conditions. Still some uncertainty in
just how strong the winds will be and if they will coincide with
the warmest and driest part of the day. Models differ in pressure
rises and wind speeds. Will let the day shift take another look
before making any decisions on potential fire weather highlites
for Friday.

Today will be the warmest day of the week with high temperatures
in the upper 90s to low 100s expected for most places. Slightly
cooler temperatures are expected behind the weak cold front on
Friday with highs in the low 90s. STP

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

Little in the way of changes for the extended forecast period.
Temperatures will be mainly in the 90s, with mostly dry
conditions for the bulk of the forecast period.

Upper level ridging will prevail across the region from Saturday
through much of the day Monday, suppressing any activity
development across the region. A low pressure system will move
through southern Alberta and Saskatchewan Monday evening into
Tuesday. This will shift the ridge eastward, bringing southwest
flow to the region and opening the door for precip chances, as a
weak cold front swings across the region overnight Monday. Some
degree of southwest flow will persist over the area through the
remainder of the period, with ridging developing over eastern
Montana. This will result in daily chances for convection across
west and central zones, with improved chances in eastern zones by
Wednesday night/Thursday as upper ridging shifts eastward. AAG

&&

.AVIATION...

Expect VFR conditions to prevail across the region today.
Thunderstorms are possible across much of the region this
afternoon/evening, with best potential from KMLS east. Some of
these storms in the east could be strong with gusty winds. AAG

&&

.PRELIMINARY POINT TEMP/POPS...

    Tdy Fri     Sat     Sun     Mon     Tue     Wed
-------------------------------------------------------
BIL 098 064/092 059/090 061/094 065/095 065/089 064/090
    2/T 20/U    00/U    10/U    11/U    21/B    22/T
LVM 094 053/089 049/088 051/092 055/092 056/086 055/087
    1/U 10/U    01/U    10/U    01/U    21/B    22/T
HDN 101 062/093 057/092 058/096 062/097 062/092 061/092
    2/T 20/U    00/U    10/U    11/U    11/B    22/T
MLS 103 069/094 060/091 061/095 067/097 066/092 066/094
    2/T 21/U    00/U    00/U    01/U    11/B    12/W
4BQ 101 065/092 059/091 059/094 066/096 065/092 063/092
    4/T 30/U    00/U    00/U    01/B    11/B    12/T
BHK 098 065/092 056/089 056/090 061/094 061/091 062/091
    4/T 41/U    01/U    00/U    02/T    11/B    12/T
SHR 098 059/089 054/089 054/093 057/095 058/089 057/090
    3/T 20/U    00/U    10/U    11/B    21/B    22/T

&&

.BYZ WATCHES/WARNINGS/ADVISORIES...
MT...Red Flag Warning in effect from noon today to 9 PM MDT Friday
      FOR ZONE 117.
     Red Flag Warning in effect from noon today to 9 PM MDT this
      evening FOR ZONES 124-127-130.
WY...None.

&&

$$
weather.gov/billings



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