Area Forecast Discussion
Issued by NWS Billings, MT

Home | Current Version | Previous Version | Text Only | Print | Product List | Glossary On
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
487
FXUS65 KBYZ 220831
AFDBYZ

Area Forecast Discussion
National Weather Service Billings MT
231 AM MDT FRI JUL 22 2016

.SHORT TERM...valid for Tdy and Sat...

Severe weather is possible this afternoon and evening over the
eastern portion of the area...E of KBIL...especially from KMLS NE.
The models were in decent agreement with some uncertainty
regarding the incoming pacific wave showing up in the ensembles.
Used a blend of deterministic and CAM for the forecast.

Early this morning, a pacific shortwave could be seen on water
vapor imagery moving into the Pacific NW. The wave was progged to
reach E WA/N ID by 00Z tonight. Energy will increase in SW flow
aloft over the area today as moisture increases in the eastern
zones due to a developing low-level jet. Precipitable waters climb
to an inch to around /1.25/ inches over the central and E today
into tonight. The SREF showed Bulk Effective Shear on the order of
40-50 kt across the far N and NE sections of the area into
tonight. SREF, NSSL WRF and RAP were in good agreement in
depicting 1000+ j/kg MUCAPES over the NE half and eastern parts of
the area. In addition to lift from shortwaves in the flow, there
will be a warm front that lifts N through through E MT. Isentropic
lift will occur over the E into tonight. Given the location of the
warm front and low-level jet, as well as other severe parameters,
there is an enhanced risk of severe weather over Fallon County
with a slight risk in adjacent areas, and a marginal risk adjacent
to the slight. Have included the mention of severe thunderstorms
in the slight and enhanced areas. Primary threats will be damaging
winds and large hail. Further W, there is the chance of strong
winds with any storms due to inverted-v sounding profiles.

Regarding fire weather concerns today into tonight, a sprawling
surface low over the area will keep wind speeds down ahead of the
cold front which was still forecast to move through tonight,
reaching KBIL around 06Z and ushering in gusty NW winds. RH`s will
be in the teens to low 20s today, and with mixing to around 500
mb, and 700 mb temperatures around +16 degrees c, highs will be
in the 90s to around 104 degrees. Convective debris may put a
damper on some of the temperatures this afternoon, after 20Z,
according to the time-lagged HRRR. Added a near-record high temperature
headline for KLVM. Will continue to headline the FWF.

Confined slight chance PoPs to just the eastern zones after 06Z
tonight, ahead of the cold front. A drier airmass will be over the
region Sat. and Sat. night despite some energy moving through the
flow aloft. It will be much cooler with mixing to 700 mb where
temperatures will be +8 to +10 degrees c on Sat., resulting in
highs in the 80s. Wind speeds in the column will be in the 20s,
resulting in gusty NW winds across the area. Humidities will drop
into the teens and 20s again. Arthur

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

Heights rise as flat ridging builds over the region on Sunday.
Models show an area of PV moving over our east early in the day,
which along with showalter indices near -1C could produce a few
showers or weak thunderstorms in far SE MT during the morning.
Have added a small pop to cover this, otherwise Sunday and Sunday
night will be quiet weather periods with temps pretty close to
normal.

Zonal flow will exist over the region Monday through Wednesday,
preventing any monsoonal surges, but with a series of weak Pacific
shortwaves bringing at least a slight chance of thunderstorms each
day. Greatest potential for storms will be in our east where
precipitable waters will be modestly higher, on the order of three
quarters of an inch. Temps should stay a little above normal for
the first half of next week. Expect highs generally in the 90s,
not extreme heat given the progressive flow.

Models in good agreement showing central plains ridge retrograding
toward the great basin by the end of the week, allowing for flow
to turn more northwesterly over our region. As a result of this
shift, expect a slight cooling trend along with an improved chance
of daily thunderstorms as shortwaves drop out of western Canada
next Thursday and Friday.

JKL

&&

.AVIATION...

VFR conditions and light winds will prevail through this morning.
Isolated to scattered thunderstorms will impact the region this
afternoon and evening. Storms near KLVM-KBIL-KSHR will be high-
based and could produce erratic wind gusts. Further east...a few
severe storms could produce hail and strong winds near KMLS-KBHK.
Eastern storms will also have a greater chance of producing local
MVFR flight conditions. Expect a cold front to bring increased
W-NW winds by the evening in western areas. JKL

&&

.PRELIMINARY POINT TEMP/POPS...

    Tdy Sat     Sun     Mon     Tue     Wed     Thu
-------------------------------------------------------
BIL 099 062/086 058/090 061/094 062/094 062/093 062/087
    2/T 21/N    11/U    11/U    12/T    22/T    23/T
LVM 097 051/083 048/089 050/093 052/092 052/091 053/086
    2/T 21/N    11/U    12/T    21/U    12/T    23/T
HDN 101 060/087 055/091 057/096 059/095 060/094 059/088
    2/T 21/N    11/U    11/U    12/T    22/T    23/T
MLS 102 066/087 059/091 063/096 065/095 065/094 064/088
    3/T 31/N    11/U    12/T    22/T    22/T    22/T
4BQ 104 064/088 057/090 060/095 062/095 062/095 063/090
    3/T 31/N    12/T    12/T    22/T    22/T    23/T
BHK 098 063/084 055/087 059/093 062/091 061/089 061/086
    4/T 41/N    11/U    12/T    23/T    32/T    23/T
SHR 100 057/087 052/091 054/095 057/096 057/095 057/088
    2/T 21/U    11/U    11/U    22/T    22/T    23/T

&&

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

&&

$$
weather.gov/billings



USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.