FXUS65 KTFX 261142
Area Forecast Discussion
National Weather Service Great Falls MT
542 AM MDT Mon Jun 26 2017
...Update to Aviation...
Upper level high pressure ridge over the region will bring hot
and dry conditions to Montana today. A surface cold front sweeps
across the state overnight for showers and thunderstorms with
cooler temperatures expected Tuesday.
Today through Wednesday...Upper level ridge moves over the region
for very warm to hot conditions today. A surface low pressure
system will develop along the east slopes of the Rockies in
southern Alberta for increasing southeast flow at the surface.
Models are in agreement that this low will progress eastward
overnight with a surface cold front sweeping through Montana early
Tuesday. This timing is about 12 to 18 hours slower than models
were indicating over the last few days. As a result, I have
lowered PoPs somewhat for today and tonight and increased them a
bit for Tuesday. Behind the cold front, breezy west to
northwesterly winds will develop across North Central Montana
for Tuesday night and Wednesday. Despite impressive CAPE values
expected across the forecast area today and Tuesday, it appears
that the risk for widespread severe weather is relatively low.
However, I still can not rule out one or two short lived storms
that could produce locally strong outflow winds and marginally
large hail, especially this evening. mpj
Wednesday Night through Sunday...An unsettled, northerly flow aloft
develops Wednesday night and Thursday associated with a closed upper
level low drifting through AB/SK. A cold front trailing behind this
system will lower temperatures into the low- to mid-70s on Thursday.
This pattern brings chances for scattered showers and thunderstorms,
although model guidance continues to differ on the timing and
spatial extent of this activity. The latest forecast guidance has
slowed the departure of the upper low, with chances for isolated
light rain showers continuing Thursday night into Friday. Model
consensus suggests weak ridging through the weekend, providing
generally fair weather with temperatures near 80F and isolated
showers or thunderstorms possible. PN
Variable high clouds will move over the forecast this morning with
increasing mid and high level clouds after 18Z. Surface winds will
also increase during the afternoon and there will be an increasing
chance for showers or thunderstorms over the Rocky Mountains by 21z.
Surface front sweeps through the region overnight with scattered
showers and thunderstorms and increasing west winds behind the
front. VFR conditions will prevail but short-lived MVFR conditons
are possible in precipitation with mountains becoming increasingly
obscured overnight. mpj
A Red Flag Warning has been issue as confidence increases that
there will be critical fire weather conditions Monday afternoon
into evening in our far northeastern areas, primarily Blaine
County. Gusty southeast winds ahead of a surface low pressure
system will combine with minimum RH values in the teens and
increasingly dry fuels in eastern portions of Fire Weather Zone
.PRELIMINARY POINT TEMPS/POPS...
GTF 92 60 77 50 / 10 40 50 20
CTB 90 58 76 48 / 10 40 40 10
HLN 93 60 78 52 / 30 50 60 10
BZN 91 54 76 47 / 10 20 60 30
WEY 81 43 68 38 / 10 30 60 30
DLN 89 54 73 47 / 10 40 50 20
HVR 95 62 81 52 / 0 20 40 20
LWT 87 58 75 48 / 0 30 50 30
Red Flag Warning from noon today to 8 PM MDT this evening Hill
and Blaine Counties.
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