504
FXUS65 KTFX 301107
AFDTFX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREAT FALLS MT
507 AM MDT FRI MAY 30 2025
AVIATION SECTION UPDATED.
KEY MESSAGES
- HOT TEMPERATURES, WITH HIGHS AROUND 90 DEGREES, ARE EXPECTED ON
SATURDAY AS HIGH PRESSURE BUILDS IN OVER THE NORTHERN ROCKIES.
- A COLD FRONT BRING COOLING TEMPERATURES FOR THE DAY ON SUNDAY,
WITH FURTHER COOLING EXPECTED INTO THE DAY ON MONDAY.
- PREDOMINATELY DRY CONDITIONS ARE EXPECTED THROUGH SATURDAY
NIGHT, WITH INCREASING PRECIPITATION CHANCES FROM SUNDAY
THROUGH TUESDAY.
DISCUSSION
/ISSUED 317 AM MDT FRI MAY 30 2025/
- METEOROLOGICAL OVERVIEW:
A BRIEF PERIOD OF NORTHWEST FLOW ALOFT COMBINED WITH A RE-ENFORCING
COLD FRONT WILL BRING PREDOMINATELY DRY AND "COOLER", ALBEIT
TEMPERATURES WILL STILL BE RUNNING 10 TO NEARLY 15 DEGREES ABOVE
NORMAL, CONDITIONS TO THE NORTHERN ROCKIES TODAY. BY THIS EVENING
TRANSIENT RIDGING WILL BEGIN TO SLIDE EAST AND OVER THE NORTHERN
ROCKIES, WITH THE RIDGE AMPLIFYING INTO THE DAY ON SATURDAY AS
SHORTWAVE TROUGHING OVER THE EASTERN PACIFIC AND GULF OF ALASKA DIGS
TOWARDS THE PACIFIC NORTHWEST. DRY AND HOT CONDITIONS ARE THEN
EXPECTED BENEATH THE AMPLIFYING RIDGE ON SATURDAY, WITH TEMPERATURES
SOARING 15 TO NEARLY 25 DEGREE ABOVE NORMAL.
FROM SUNDAY THROUGH MONDAY THE AFOREMENTIONED SHORTWAVE OVER THE
PACIFIC NORTHWEST WILL BEGIN TO SPLIT, WITH THE NORTHERN WAVE
LIFTING NORTHEAST TO OVER THE CENTRAL PRAIRIE PROVINCES OF CANADA
WHILE THE SOUTHERN WAVE DIGS SOUTHEAST OVER THE CALIFORNIA COAST. AS
THE NORTHERN SHORTWAVE APPROACHES THE NORTHERN ROCKIES ON SUNDAY
EXPECT TEMPERATURES TO TREND SLIGHTLY COOLER AS A COLD FRONT PUSH
SOUTH FROM CANADA, WITH INCREASING CHANCES FOR SHOWERS AND
THUNDERSTORMS ALONG BEHIND THE ADVANCING COLD FRONT. TEMPERATURES ON
MONDAY IN WAKE OF THE COLD FRONT WILL BE BELOW TO WELL BELOW NORMAL
AS HIGHS ONLY WARM INTO THE 50S TO MID-60S, WITH CONTINUED CHANCES
FOR PRECIPITATION.
MOIST, NORTHWEST FLOW FROM TUESDAY THROUGH THE END OF THE UPCOMING
WORK WEEK WILL SUPPORT ISOLATED TO SCATTERED SHOWERS AND
THUNDERSTORMS ACROSS THE NORTHERN ROCKIES, ESPECIALLY OVER AND NEAR
THE HIGHER TERRAIN; WITH TEMPERATURES SLOWLY MODERATING BACK ABOVE
NORMAL THROUGH THE SECOND HALF OF THE WORK WEEK. - MOLDAN
- FORECAST CONFIDENCE & SCENARIOS:
HOT TEMPERATURES ON SATURDAY :
TRANSIENT, BUT STRONG, UPPER LEVEL RIDGING WILL MOVE OVER THE
NORTHERN ROCKIES ON SATURDAY, WITH H500 HEIGHTS RUNNING NEARLY 3
STANDARD DEVIATIONS ABOVE NORMAL. CLIMATE ANOMALY INDICATORS SUCH AS
THE ECMWF EFIS SUPPORT AN UNUSUALLY HOT DAY BENEATH THIS RIDGE, WITH
EFI VALUES ACROSS SOUTHWEST THROUGH NORTH CENTRAL MONTANA LARGELY
RANGING FROM 0.8 TO 0.95. NBM PROBABILITIES FOR HIGH TEMPERATURES OF
90 DEGREES OR WARMER ARE THE HIGHEST ACROSS THE GOLDEN TRIANGLE
REGION OF THE CENTRAL AND NORTH CENTRAL MONTANA PLAINS AND IN THE
HELENA VALLEY WHERE VALUES OF 80% TO NEARLY 100% ARE COMMON.
THE TABLE BELOW SHOWS THE LATEST NBM PROBABILITIES FOR NEW RECORD
HIGH TEMPERATURES BEING SET ON SATURDAY, WITH THE CURRENT RECORD
HIGHS IMMEDIATE ADJACENT TO THE PROBABILITIES.
LOCATION FRIDAY
CUT BANK 99% BREAKING 86 DEGREES
HAVRE 4% BREAKING 94 DEGREES
GREAT FALLS 76% BREAKING 90 DEGREES
LEWISTOWN 12% BREAKING 87 DEGREES
HELENA 99% BREAKING 88 DEGREES
BOZEMAN 88% BREAKING 88 DEGREES
DILLON 44% BREAKING 87 DEGREES
RAIN FROM SUNDAY THROUGH TUESDAY :
AN UNSETTLED PATTERN IS STILL EXPECTED ACROSS THE NORTHERN ROCKIES
FROM THE SECOND HALF OF THE WEEKEND THROUGH THE FIRST HALF OF THE
UPCOMING WORK WEEK; HOWEVER, THE MAGNITUDE AND AREAL COVERAGE OF
PRECIPITATION CONTINUES TO DECREASE. LATEST NBM PROBABILITIES FOR
PRECIPITATION AMOUNTS IN EXCESS OF 0.5" GENERALLY RANGE FROM A 20-
50% CHANCE ACROSS MOST OF SOUTHWEST THROUGH NORTH CENTRAL MONTANA,
WITH THE EXCEPTION OF THE BIG BELTS, LITTLE BELTS, MEAGHER COUNTY
VALLEYS, AND JUDITH AND FERGUS COUNTIES WHERE PROBABILITIES RANGE
FROM A 60-70% CHANCE. - MOLDAN
AVIATION
30/12Z TAF PERIOD
VFR CONDITIONS WILL PREVAIL THROUGHOUT THE 3012/3112 PERIOD. A
RE-ENFORCING COLD FRONT SWEEPING SOUTHEAST ACROSS THE PLAINS OF
CENTRAL AND NORTH CENTRAL MONTANA THIS MORNING WILL BRING A 6-9
HOUR WINDOW OF BREEZY AND GUSTY NORTHWEST WINDS TO THE KCTB, KHVR,
AND KLWT TERMINALS. ADDITIONALLY, A ISOLATED SHOWER OR TWO CAN'T
BE RULED OUT AT THE KHVR TERMINAL AS THIS FRONT MOVES TO THE
SOUTHEAST. WIDESPREAD MOUNTAIN OBSCURATION IS NOT EXPECTED, BUT
SOME OF THE HIGHEST PEAKS ACROSS CENTRAL AND NORTH CENTRAL
MONTANA WILL BE OBSCURED THROUGH THE MORNING HOURS. - MOLDAN
REFER TO WEATHER.GOV/ZLC FOR MORE DETAILED REGIONAL
AVIATION WEATHER AND HAZARD INFORMATION.
PRELIMINARY POINT TEMPS/POPS
GTF 77 49 91 57 / 0 0 0 0
CTB 78 46 89 56 / 10 0 0 10
HLN 82 50 92 57 / 0 0 0 0
BZN 78 44 87 52 / 10 0 0 0
WYS 74 35 79 40 / 0 0 0 0
DLN 76 45 87 51 / 10 0 0 0
HVR 79 46 90 57 / 20 0 0 10
LWT 72 45 84 58 / 10 0 0 10
TFX WATCHES/WARNINGS/ADVISORIES
NONE.
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