216
FXUS65 KGGW 252102
AFDGGW
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GLASGOW MT
302 PM MDT THU APR 25 2024
DISCUSSION
KEY MESSAGES:
1) AN INCREASE IN INSTABILITY FOR AREAS MAINLY SOUTH OF I-94
MAINTAINS CHANCES FOR THUNDERSTORMS WITH GUSTY WINDS THROUGH THIS
EVENING.
2) FOR FRIDAY, ELEVATED TO CRITICAL FIRE WEATHER CONDITIONS DUE
TO LOW HUMIDITY AND GUSTY WINDS PROMPT A RED FLAG WARNING FOR
NORTHEASTERN PORTIONS OF THE AREA.
3) LOOK FOR A GRADUAL TEMPERATURE INCREASE EXPECTED IN THE
UPCOMING WEEK WITH ISOLATED CHANCES FOR PRECIPITATION.
WEATHER PATTERN OVERVIEW:
SURFACE LOW PRESSURE STRENGTHENS ALONG A NORTH-TO-SOUTH BOUNDARY
EXTENDING FROM EASTERN MONTANA DOWN INTO THE EASTERN PLAINS OF
COLORADO. A SHORTWAVE TROUGH ALOFT, MOISTURE TRANSPORT IN THE LOW
AND MID-LEVELS, AND TEMPERATURES 10-20 DEGREES ABOVE NORMAL WILL
INCREASE INSTABILITY FOR LOCATIONS EAST OF THIS BOUNDARY. FOR
NORTHEAST MONTANA, THIS IS AREA IS FOCUSED SOUTH OF I-94.
CONVECTION INITIATION IS OCCURRING THIS AFTERNOON OFF THE HIGHER
TERRAIN IN SOUTHEAST MONTANA AND SOUTH DAKOTA, THOUGH A FEW OF
THESE STORMS MAY DEVELOP CLOSER TO THE YELLOWSTONE RIVER VALLEY.
ANY STORMS THAT DO DEVELOP WILL PULSE UP AND DOWN, WITH THE
GREATEST THREAT IN THE STRONGEST OF STORMS BEING HAIL. ANY STORMS
THAT CONTINUE BEYOND THE END OF DAYTIME HEATING THIS EVENING WILL
QUICKLY DIMINISH AS THEY MOVE TO THE NORTHEAST.
FURTHER DISCUSSION REGARDING A RED FLAG WARNING ISSUED FOR FRIDAY
CAN BE FOUND IN THE FIRE WEATHER SECTION BELOW.
FROM SUNDAY, THE SOUTHWEST FLOW ALOFT WILL BRING BOUTS OF ISOLATED
TO SCATTERED SHOWERS FROM MONDAY INTO THURSDAY AND AN INCREASING
TEMPERATURE TREND THROUGH THE END OF THE WEEK.
CONFIDENCE AND POTENTIAL DEVIATIONS FROM BASE FORECAST:
GIVEN THAT ACTUAL RH VALUES HAVE TENDED TO FALL BELOW NBM
GUIDANCE PARTICULARLY FOR FAR NE MONTANA, A REDUCTION OF AROUND
3% IN RH VALUES WAS MADE ACCORDINGLY ON FRIDAY. OTHERWISE, THERE
IS HIGH CONFIDENCE FOR TEMPERATURES INTO EARLY NEXT WEEK AND
MEDIUM CONFIDENCE FOR THE WIND FORECAST ON FRIDAY.
-ENRIQUEZ/ZANKER
AVIATION
LAST UPDATED: 2100Z
FLIGHT CAT RANGE: VFR (MVFR IN SHOWER/THUNDERSTORM)
DISCUSSION: PRIMARILY MID LEVEL CLOUDS ARE MOVING THROUGH THE
REGION. LATE THIS AFTERNOON AND EVENING, CONVECTIVE SHOWERS AND A
FEW THUNDERSTORMS HAVE A MEDIUM (30-40%) CHANCE TO BRIEFLY IMPACT
KSDY AND KGDV. ANY OUTFLOW BOUNDARIES MAY LEAD TO A SUDDEN
ERRATIC WIND SHIFT AND HIGHER GUSTS.
FIRE WEATHER
AN UPGRADE TO A RED FLAG WARNING FROM NOON THROUGH 8PM FRIDAY HAS
BEEN MADE FOR ZONES 120 AND 122, ALONG WITH ZONE 134 ADDED IN. AN
INCREASE IN SHOWER AND THUNDERSTORM ACTIVITY WITH THEIR
ASSOCIATED OUTFLOW BOUNDARIES MAY AT TIMES BRING GUSTY AND ERRATIC
WINDS MAINLY SOUTH OF I-94 THROUGH THE EARLY EVENING HOURS TODAY.
ON FRIDAY, WINDS GUSTING AS HIGH AS 35 MPH WITH HUMIDITY AS LOW
AS 17 PERCENT INCREASES FIRE RISK FOR FAR NORTHEAST MONTANA IN
PARTICULAR, THUS PROMPTING AN UPGRADE TO A RED FLAG WARNING FROM
NOON THROUGH 8 PM. THERE IS HIGH CONFIDENCE FOR CRITICAL
CONDITIONS FROM THE LOW RH AND WIND COMBO ACROSS ZONE 120 AND MORE
MODERATE CONFIDENCE FOR ZONES 122 AND 134. PRECIPITATION OVER THE
LAST TWO WEEKS HAS BEEN MUCH BELOW NORMAL ALONG WITH FUEL
MOISTURE DEFICITS. FIRE WEATHER CONCERNS DECREASE OVER THE WEEKEND
AS WINDS BACK OFF.
GGW WATCHES/WARNINGS/ADVISORIES
RED FLAG WARNING FROM NOON TO 8 PM MDT FRIDAY FOR
DAWSON/MCCONE/PRAIRIE/RICHLAND/WIBAUX COUNTIES-FORT PECK
RESERVATION AND DANIELS/ROOSEVELT/SHERIDAN COUNTIES-NORTHERN
VALLEY AND NORTHERN PHILLIPS COUNTIES.
WEATHER.GOV/GLASGOW
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