063
FXUS65 KTFX 272011
AFDTFX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREAT FALLS MT
111 PM MST MON JAN 27 2025
KEY MESSAGES
- DRY CONDITIONS PERSIST WITH INCREASINGLY MILD TEMPERATURES
THROUGH FRIDAY.
- GUSTY WINDS ON THE PLAINS CONTINUE WITH A MORE WIDESPREAD RISK
FOR LOCALLY STRONG WINDS DEVELOPING FRIDAY AND SATURDAY.
- A CHANGE TO MUCH COLDER TEMPERATURES WITH INCREASING CHANCES
FOR ACCUMULATING SNOW DEVELOPS THIS WEEKEND.
DISCUSSION
- METEOROLOGICAL OVERVIEW:
A BLOCKING (REX) UPPER LEVEL PATTERN IS IN PLACE WITH RIDGING
FROM OFFSHORE OF THE PACIFIC NW INTO NW CANADA SITUATED TO THE
NORTH OF A CLOSED LOW CENTERED OVER SOUTHERN CA. THIS PATTERN
GRADUALLY DE-AMPLIFIES THROUGH THE WEEK WITH DRY NORTHERLY FLOW
ACROSS THE AREA TRANSITIONING TO WESTERLY AS THE WEEK PROGRESSES.
MID-LEVEL TEMPERATURES CONTINUE TO WARM THROUGH WEDNESDAY FOR
INCREASINGLY MILD CONDITIONS, ESPECIALLY ACROSS THE PLAINS, WHERE
DAYTIME TEMPERATURES ARE LIKELY TO REACH THE 40S WED THROUGH
FRI. WARMING WILL BE SLOWER ACROSS SW MT VALLEYS WHERE COLD POOLS
BENEATH A STRONG TEMPERATURE INVERSION WILL BE SLOW TO ERODE.
WHILE SURFACE HIGH PRESSURE CENTERED ACROSS THE INTERIOR WESTERN
US WILL KEEP WINDS LIGHT IN SW MT VALLEYS THROUGH WEDNESDAY, THE
PRESSURE GRADIENT ACROSS THE ROCKIES WILL MAINTAIN BREEZY TO
LOCALLY WINDY CONDITIONS ACROSS THE NORTH-CENTRAL MT PLAINS WITH
MOST AREAS SEEING AN UPTICK IN WINDS THURSDAY AND FRIDAY AS
SURFACE HIGH PRESSURE WEAKENS AND WESTERLY FLOW ALOFT INCREASES.
BIG CHANGES ARE EXPECTED THIS WEEKEND AS TROUGHING DIGS SOUTH
THROUGH WESTERN CANADA THEN ELONGATES WESTWARD OFF THE THE SW BC
COAST WITH DIFFERING SCENARIOS AMONG LONGER RANGE MODELS. THE
GENERAL PATTERN WILL SUPPORT A COLD AIRMASS MOVING SOUTH INTO THE
AREA AS EARLY AS SATURDAY WITH MUCH COLDER TEMPERATURES LIKELY
ACROSS AT LEAST NORTH-CENTRAL MT FOR SUNDAY INTO EARLY NEXT WEEK.
THIS WOULD BE PRECEDED BY A PACIFIC COLD FRONT AND INCREASED RISK
FOR STRONGER WINDS AND SOME MOUNTAIN PRECIPITATION FRIDAY NIGHT
INTO SATURDAY BEFORE AN ARCTIC FRONT SLIDES SOUTH INTO THE AREA
LATE SATURDAY OR SATURDAY NIGHT WITH CHANCES FOR MORE WIDESPREAD
SNOW INCREASING SUNDAY INTO EARLY NEXT WEEK AS PACIFIC MOISTURE IS
DRAWN INTO THE REGION.
- FORECAST CONFIDENCE & SCENARIOS:
SW VALLEY TEMPERATURES:
MAX AND MIN TEMPERATURES WERE ADJUSTED TOWARD THE 10TH PERCENTILE
OF FORECAST ENSEMBLES THROUGH TUESDAY ACROSS SW MT VALLEY
LOCATIONS, WITH THE COLD POOL LIKELY TO SHRINK BUT LINGER INTO
WEDNESDAY FROM THE HELENA VALLEY SE THROUGH THE GALLATIN VALLEY.
WEEKEND WINTER WEATHER HAZARDS:
THE BREAKDOWN OF THE UPPER LEVEL RIDGE AND INCREASED WESTERLY
FLOW ALOFT, ALONG WITH A PACIFIC COLD FRONT AND SURFACE LOW
PRESSURE TRACKING EAST ALONG THE CANADIAN BORDER WILL BRING WINDY
CONDITIONS TO MUCH OF THE AREA LATE FRIDAY INTO SATURDAY. WHILE
PROBABILITIES FOR STRONG WINDS (GUSTS > 50 MPH) ARE CURRENTLY LOW
(<40%) EXCEPT ALONG THE ROCKY MTN FRONT, THE COLD FRONT AND DEEPER
MIXING FOLLOWING IT COULD PROVIDE A FOCUS FOR STRONGER WIND GUSTS
THAN CURRENTLY ANTICIPATED.
THE MAJORITY OF MODEL ENSEMBLES SHOW AN ARCTIC COLD FRONT AND
MUCH COLDER AIRMASS PUSHING SOUTH INTO NORTH-CENTRAL MT LATE
SATURDAY OR SATURDAY NIGHT BUT IF/WHEN IT PROGRESSES THROUGH SW
MT REMAINS LESS CERTAIN. A PERIOD OF SNOW AND GUSTY NORTH WINDS
WILL LIKELY ACCOMPANY AND FOLLOW THE FRONT WITH POTENTIAL FOR COLD
WEATHER HAZARDS ASSOCIATED WITH THE FALLING TEMPERATURES AND
COMBINED WIND. THE PROBABILITY FOR SUBZERO MAXIMUM TEMPERATURES ON
SUNDAY RANGES FROM AROUND 70% ACROSS GLACIER COUNTY TO 30% FROM
GREAT FALLS TO LEWISTOWN WITH PROBABILITIES FOR SUBZERO MAX
TEMPERATURES INCREASING TO 60-70% OR HIGHER ACROSS MOST OF NORTH-
CENTRAL MT ON MONDAY.
DETAILS REGARDING SNOW/PRECIPITATION AMOUNTS THIS WEEKEND ARE
STILL EVOLVING WITH MEASURABLE SNOW INITIALLY LIKELY TO FOCUS ON
MOUNTAIN AREAS AND NEAR CONTINENTAL DIVIDE THROUGH SATURDAY WITH
INCREASING CHANCES FOR MORE WIDESPREAD ACCUMULATING SNOW
DEVELOPING SUNDAY INTO MONDAY. WHILE MOST AREAS HAVE AT LEAST A
30% CHANCE FOR AN INCH OR MORE OF SNOWFALL SUNDAY/MONDAY, AREAS
FROM THE ROCKY MOUNTAIN FRONT EAST ACROSS CENTRAL MT HAVE A 30-50%
CHANCE OF SNOWFALL AMOUNTS IN EXCESS OF 4 INCHES. HOENISCH
AVIATION
27/18Z TAF PERIOD
VFR CONDITIONS PREVAIL THIS TAF PERIOD. BREEZY WINDS ACROSS THE
PLAINS WILL PERSIST INTO MUCH OF THE OVERNIGHT. OTHERWISE THE ONLY
OTHER CONCERN WILL BE FOR SOME PATCHY FOG IN CENTRAL AND SOUTHWEST
MONTANA VALLEYS TONIGHT. -AM
REFER TO WEATHER.GOV/ZLC FOR MORE DETAILED REGIONAL AVIATION
WEATHER AND HAZARD INFORMATION.
PRELIMINARY POINT TEMPS/POPS
GTF 19 37 21 43 / 0 0 0 0
CTB 21 38 22 40 / 0 0 0 0
HLN 3 24 8 35 / 0 0 0 0
BZN -5 26 4 35 / 0 0 0 0
WYS -18 35 -8 37 / 0 0 0 0
DLN 1 30 11 38 / 0 0 0 0
HVR 19 36 15 38 / 0 0 0 0
LWT 22 41 21 46 / 0 0 0 0
TFX WATCHES/WARNINGS/ADVISORIES
NONE.
HTTP://WWW.WEATHER.GOV/GREATFALLS
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