Area Forecast Discussion
Issued by NWS Great Falls, MT
FXUS65 KTFX 241741
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREAT FALLS MT
1135 AM MDT Thu Jul 24 2014
UPDATED AVIATION SECTION
Update forthcoming. Upper low continues to track east across
southern Canada. Low level moisture and shear values of 50 kts or
greater along the Hi-Line have resulted in isolated thunderstorms
this morning. Have increased POPs for this area for the remainder of
the morning. West winds have begun to increase where the high wind
warning is currently out. Temperatures look OK.
VFR conditions are expected to continue through at least the next 24
hours. Isolated showers and thunderstorms have developed this
morning ahead of an approaching shortwave trough in an area of
unstable air, between KCTB and a KBTM-KHVR line. Am expecting this
development to move east across the area through 00Z as the
shortwave moves into the area. These storms should be fairly weak
and likely only produce brief heavy rain and gusty winds, with small
hail possible. Brief MVFR conditions are possible with heavier rain.
Otherwise, the main impact to the area will be strong westerly winds
driven by the shortwave. Winds are already fairly strong at KCTB,
and these winds will increase from west to east across the area. The
strongest winds are expected to be along the Rocky Mountain Front
and along the Hi-Line where gusts will likely exceed 40 kt at times.
From the KLWT area into southwest Montana, winds will not be quite
as strong. As the shortwave exits the area after 00Z, winds will
gradually decrease, but they will remain breezy over the plains of
north central Montana.
.PREV DISCUSSION...Issued 348 AM MDT Thu Jul 24 2014
Thursday through Saturday...Another round of active weather is
expected today as a low pressure system moves across the area
bringing widespread gusty winds and fire weather concerns. A high
winds warning remains in affect for the Northern Rocky Mountain
Front and adjacent high plains. Due to low minimum RH values
coinciding with the timing of the strongest winds, the fire
weather watch will be upgraded to a red flag warning. Once the low
pressure system moves off to the north east a ridge of high
pressure will begin to build into the area. This pattern change
does not bring any significant chances of widespread
precipitation, but will begin to warm temperatures back towards
seasonal averages behind the cooling expected Thursday.
Saturday night through Wednesday...Models agree with the idea of
having a strong ridge aloft over the western U.S. For the lower
elevations in the forecast area highs in the 80s Sunday and Monday
will warm into the upper 80s to lower 90s Tuesday and Wednesday.
The ridge will result in dry conditions with the possible
exception of isolated thunderstorms over the western mountains and
southwest Montana. For fire weather this pattern will lead to
increased curing of fuels. Winds will be less than 10 mph and
lightning activity should be minimal.
Have upgraded the Fire Weather Watch for fire zone 115
(Chouteau/Fergus counties) and the southern third of Blaine County
to a red flag warning from noon Thursday until midnight Friday
Morning. RH values are expected to drop into the teens when winds
are near their strongest values with most locations seeing sustained
winds at 20 to 30 mph with gusts around 40 mph. There is also
concern that lightning starts from thunderstorms Wednesday Night may
hold over and then spread as the strong winds develop today. Suk
.PRELIMINARY POINT TEMPS/POPS...
GTF 80 51 77 49 / 10 10 10 0
CTB 71 50 72 47 / 20 10 10 10
HLN 79 53 80 53 / 10 10 0 0
BZN 82 43 80 44 / 10 10 0 0
WEY 75 33 73 34 / 10 0 0 0
DLN 77 44 77 45 / 10 10 0 0
HVR 81 52 79 51 / 20 10 10 10
LWT 81 49 79 49 / 20 10 10 0
RED FLAG WARNING from Noon today to Midnight MDT tonight
HIGH WIND WARNING until Midnight MDT tonight Northern Rocky
HIGH WIND WARNING until Midnight MDT tonight Eastern Glacier...