751
FXUS65 KGGW 130422
AFDGGW
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GLASGOW MT
1022 PM MDT SAT SEP 12 2026
KEY MESSAGES
- RAIN WILL BE LIKELY ACROSS NORTHEAST PORTIONS OF MONTANA SUNDAY
EVENING THROUGH MONDAY AFTERNOON. PRECIPITATION TOTALS WILL
RANGE BETWEEN 0.01" AND 0.25".
- A LAKE WIND ADVISORY HAS BEEN ISSUED DUE TO SE WIND BEING
EXPECTED TO REACH 20 TO 25 MPH SUSTAINED SUNDAY AFTERNOON. WAVE
HEIGHTS HAVE THE POTENTIAL TO REACH 3 FT.
- SW WINDS WILL LIKELY REACH LAKE WIND ADVISORY CRITERIA AGAIN
MONDAY AFTERNOON. WAVE HEIGHTS HAVE THE POTENTIAL TO REACH 4.5
FT.
DISCUSSION
SYNOPTIC SETUP: FORECAST BEGINS WITH A WEAK RIDGE POKING UP FROM
COLORADO THROUGH WYOMING AND INTO EASTERN MONTANA. FAR TO THE
WEST A CLOSED LOW HAS BEGUN MOVING ONTO THE SHORE OF THE PACIFIC
NORTHWEST. IN BETWEEN THESE TWO AIRMASSES SW FLOW HAS SET UP IN
BETWEEN PULLING IN PACIFIC MOISTURE FROM OFF THE COAST OF NORTHERN
CALIFORNIA INTO IDAHO AND WESTERN MONTANA.
TODAY THROUGH THIS EVENING: RIDGE EXITING TO THE WEST WILL KEEP
CONDITIONS STABLE THROUGH MOST OF THE DAY AND THEREFORE DRY.
HOWEVER AS THE CLOSED LOW TO THE WEST MOVES INLAND OVER THE PCNW A
SURFACE PRESSURE GRADIENT WILL FORM CREATING A STRONG WIND THAT
WILL EASILY LEAD TO A LAKE WIND ADVISORY THIS AFTERNOON.
MONDAY MORNING TO EVENING: WHILE THE STABILITY IN THE UPPER
ATMOSPHERE WILL KEEP CONDITIONS DRY INTO THE EARLY EVENING. THE
EXIT OF THE TROUGH AND ENTRANCE OF SW FLOW WILL ALLOW ENOUGH
INSTABILITY AND PACIFIC MOISTURE TO STRIKE OFF SOME SCATTERED
RAIN SHOWERS AND EMBEDDED THUNDERSTORMS AROUND MIDNIGHT LASTING THROUGH
MONDAY AFTERNOON. COLD FRONT ASSOCIATED WITH THE TROUGH WILL
LIKELY PASS ACROSS THE AREA FROM MIDNIGHT TO 6AM AND PRODUCE
PRECIPITATION TOTALS RANGING BETWEEN 0.01" AND 0.25". THE FRONT
ITSELF HAS BACKED UP 6 TO 12 HOURS FROM THE PREVIOUS FORECAST SO
THEIR IS LOWER CONFIDENCE IN THE TIMING OF THE PASSAGE AND
ASSOCIATED SHOWERS.
WIND WILL VEER WESTERLY BEHIND THE FRONT MONDAY MORNING. THIS
WILL OF COMPARABLE IN STRENGTH TO TODAY IN REACHING ADVISORY
CRITERIA. WAVE HEIGHTS HAVE THE POTENTIAL TO REACH 4.5 FT,
PARTICULARLY MONDAY AFTERNOON.
TUESDAY ONWARD: THE TROUGH WILL FULLY EXIT THE REGION TUESDAY
MORNING WITH THE ZONAL FLOW LEFT IN ITS WAKE. SLIGHT CHANCES FOR
RAIN SHOWERS ARE POSSIBLE TUESDAY NIGHT INTO WEDNESDAY MORNING DUE
TO A SWATH OF PACIFIC MOISTURE MOVING THROUGHOUT. CONFIDENCE IN
RAIN AMOUNTS ARE LOW. RAIN CHANCES DIMINISH WEDNESDAY AFTERNOON
AS SKIES CLEAR AND TEMPERATURES WARM UNDER A DEVELOPING RIDGE OVER
THE PCNW THURSDAY. A WEAK TROUGH HAS EMBEDDED ITSELF BETWEEN US
AND THE RIDGE IN A SIGNIFICANT PORTION OF THE ENSEMBLES WHICH IS
LOWERING CONFIDENCE HEAVILY FROM THURSDAY ONWARD.
FORECAST CONFIDENCE & DEVIATIONS:
NO DEVIATION FROM NBM WERE OBSERVED.
THERE IS HIGH CONFIDENCE IN SUSTAINED WINDS AT OR ABOVE 20 MPH ON
SUNDAY AND MONDAY ACROSS FORT PECK LAKE.
THERE IS MODERATE CONFIDENCE TIMING OF SCATTERED SHOWERS AND
THUNDERSTORMS MONDAY MORNING,(THEY COULD BEGIN EARLIER OR LATER)
BUT THERE HIGH CONFIDENCE IN THEM LASTING INTO THE EVENINGS
HOURS.
THERE IS LOW CONFIDENCE IN THE FORECAST BEYOND THURSDAY.
DON/GAH
AVIATION
LAST UPDATED: 0500Z
FLIGHT CAT RANGE: VFR
DISCUSSION: BKN CLOUDS BETWEEN 50 TO 100 HFT AGL WILL LIKELY CLEAR
OUT FROM WEST TO EAST OVERNIGHT INTO SUNDAY MORNING. HIGH CLOUDS
WILL THEN ENTER DURING THE SUNDAY EVENING HOURS AND SLOWLY DROP
TO MID LEVELS AS A DISTURBANCE AND FRONT APPROACHES. THIS
DISTURBANCE WILL BRING SCATTERED RAIN SHOWERS AND THUNDERSTORMS TO
THE TERMINALS MONDAY MORNING.
SFC WIND: E AT 10 KTS OR LESS THROUGH THE MORNING. VEERING SE AND
INCREASING TO 10 TO 20 GUST 30 KTS IN THE AFTERNOON AND EVENING.
VEERING RAPIDLY W TO NW AFTER AFTER THE PASSAGE OF A COLD FRONT
AROUND MIDNIGHT.
DON/GAH
GGW WATCHES/WARNINGS/ADVISORIES
LAKE WIND ADVISORY FROM 10 AM SUNDAY TO MIDNIGHT MDT SUNDAY
NIGHT FOR CENTRAL AND SOUTHEAST PHILLIPS-CENTRAL AND SOUTHERN
VALLEY-GARFIELD-MCCONE-PETROLEUM.
WEATHER.GOV/GLASGOW
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