406
FXUS65 KGGW 021037
AFDGGW
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GLASGOW MT
437 AM MDT FRI JUN 2 2023
DISCUSSION
MORNING DISCUSSION:
LIGHT SHOWERS WILL CONTINUE ACROSS OUR REGION THROUGH THE MORNING,
GRADUALLY INCREASING AS WE HEAD INTO THE AFTERNOON AND EVENING
HOURS. MORNING ACCUMULATIONS ARE EXPECTED TO BE LESS THAN A TENTH
OF AN INCH FOR MOST LOCATIONS WITH HIGHER AMOUNTS EXPECTED LATER
THIS AFTERNOON AS THUNDERSTORMS BEGIN TO DEVELOP.
WHEN EVALUATING THE QPF AGAIN THIS MORNING, QPF TOTALS DECREASED
SLIGHTLY BUT STILL REMAIN HIGH ENOUGH TO JUSTIFY THE FLOOD WATCH
ESPECIALLY GIVEN SOME OF THE RAIN RATES WE RECEIVED ACROSS THE
REGION LAST NIGHT. THAT BEING SAID, THERE WAS NO REASON TO EXPAND
THE WATCH PAST ITS CURRENT BOUNDARIES AS THE MAIN THREAT WILL
REMAIN TOWARDS THE EAST, PARTICULARLY IN PHILLIPS, VALLEY,
PETROLEUM, AND GARFIELD COUNTIES. STORM TOTAL QPF IS EXPECTED TO
RANGE FROM HALF AN INCH IN OUR EASTERN ZONES TO AS MUCH AS AN INCH
AND A HALF IN OUR WESTERN ZONES WITH LOCALLY HIGHER AMOUNTS
POSSIBLE.
REGARDING THE SEVERE THREAT FOR THIS AFTERNOON THERE ARE A FEW
THINGS TO NOTE. 0-6 KM BULK SHEAR LOOKS TO MAX OUT ACROSS THE
CENTRAL PORTION OF OUR CWA IN THE RANGE OF 30 TO 55 KTS. MLCAPE
VALUES LOOK TO BE GENERALLY LESS THAN 1000 J/KG WITH SPORADIC
MLCIN VALUES THAT RANGE FROM NOTHING TO -150 J/KG. SOME OF THE
CAMS ARE PICKING UP ON A POTENTIAL FOR SOME SEVERE WEATHER IN THE
AREA AND OVERALL SEEM TO BE MORE ROBUST WITH PREDICTIONS COMPARED
TO WHAT WAS SEEN THIS TIME YESTERDAY MORNING WITH REGARDS TO
YESTERDAY AFTERNOON. BUT THE DISCLAIMER WORTH ADDING IS THAT THE
CAMS HAVE STRUGGLED AS OF LATE TO CAPTURE THE FULL PICTURE OF HOW
PRECIP HAS DEVELOPED AND MOVED ACROSS OUR REGION.
WHEN PAINTING AN OVERALL PICTURE FOR THE CHANCE OF SEVERE WEATHER
THIS AFTERNOON THE BEST CONSENSUS IS THERE IS CERTAINLY A CHANCE
FOR SEVERE THUNDERSTORMS BUT THERE IS STILL A DECENT BIT OF
UNCERTAINTY WHEN TRYING TO PIN DOWN THE LOCATION AND EXTENT OF THE
GREATEST THREAT. AND WITH MOSTLY CLOUDY SKIES EXPECTED TO
CONTINUE THROUGH MOST OF THE DAY, THE LACK OF GOOD DIURNAL HEATING
MIGHT BECOME A HINDRANCE FOR STORM DEVELOPMENT IN SOME LOCATIONS.
THAT BEING SAID, THIS AFTERNOON WILL NEED TO BE MONITORED CLOSELY
FOR ANY CHANGES.
-THOR
PREVIOUS DISCUSSION:
THE STAGE IS SET FOR A MULTI-DAY HEAVY RAIN EVENT (OR SERIES OF
EVENTS) TO IMPACT MOST OF NORTHEAST MONTANA TONIGHT THROUGH
SATURDAY MORNING.
AN OVERALL STAGNANT FLOW PATTERN WITH HIGHER PRESSURE TO THE EAST
AND LOWER PRESSURE TO OUR WEST WILL BOTH COMBINE TO DRAW IN
MOISTURE TRANSPORT FROM THE PACIFIC OCEAN AND THE GULF OF MEXICO.
THESE MOISTURE SOURCES WILL TRAVEL OUR DIRECTIONS AND CONVERGE AND
WRAP UP INTO NE AND NC MONTANA, PRODUCING MULITPLE WAVES OF HEAVY
RAIN AMID SCATTERED GENERAL THUNDERSTORMS. GIVEN THE LACK OF SHEAR
IN THIS ENVIRONMENT, THE MAIN THREAT OBVIOUSLY WITH ANY OF THESE
STORMS WILL BE HEAVY RAIN AND FLOODING. MINOR THREATS WOULD BE
LIGHTNING AND GUSTY WINDS.
FOLLOWING THE BEST MODEL CONSENSUS FOR TIMING AND AMOUNT OF
RAINFALL, I FELT IT WAS BEST TO UPDATE/EXPAND THE AREA OF THE
FLOOD WATCH TO NOW INCLUDE ANOTHER TIER OF ZONES EASTWARD. FOR
MORE INFORMATION, REFER TO THE HYDROLOGY DISCUSSION BELOW.
FROM SATURDAY NIGHT MOVING FORWARD, THE STAGNANT FLOW PATTERN
REMAINS, AS WE CONTINUED TO BE SANDWICHED BETWEEN LOW PRESSURE
FROM THE WEST AND HIGH PRESSURE FROM THE EAST. UNUSUALLY HUMID AIR
WILL REMAIN OVER OUR REGION FOR THE FORESEEABLE FUTURE. MODELS
SHOW SHOWERS AND THUNDERSTORMS NEARLY EVERY DAY, BUT CONFIDENCE IS
AVERAGE TO BELOW AVERAGE FOR DETAILS ON TIMING AND AMOUNTS.
----BMICKELSON
AVIATION
UPDATED: 0930Z
FLIGHT CAT: VFR WITH ISOLATED MVFR WITH THUNDERSTORMS
DISCUSSION: ANOTHER ROUND OF SHOWERS AND THUNDERSTORMS ARE
EXPECTED TODAY AS A SLOW MOVING LOW MIGRATES ACROSS OUR REGION.
LIGHT RAIN IS EXPECTED IN THE MORNING FOR PRIMARILY KGGW AND KOLF
WITH A POSSIBLE STRAY SHOWER FOR KSDY. SHOWERS WILL GRADUALLY
INCREASE TO THE EAST BY THE AFTERNOON WITH THE HEAVIEST RAIN
REMAINING TOWARDS THE WEST.
THE GREATEST THREAT OF THUNDERSTORMS WILL BE FROM 00Z FRIDAY TO
06Z SATURDAY WITH HEAVY RAIN AND ERRATIC GUSTY WINDS POSSIBLE
DURING THIS TIME. EXPECT TAF AMENDMENTS, PARTICULARLY IN THE
AFTERNOON AND EVENING.
WINDS: WIND SPEED AND DIRECTION MAY SHIFT ERRATICALLY UNDER
THUNDERSTORMS.
-KGGW/KOLF: EAST AT 5 TO 15 KTS BECOMING NORTHEASTERLY AT 10 TO 15
KTS AFTER 00Z
-KGDV/KSDY: EAST AT 5 TO 10 KTS BECOMING SOUTHEASTERLY AT 10 TO
15 KTS AFTER 18Z, SHIFTING BACK TO EASTERLY AT 5 TO 15 KTS AFTER
03Z
-THOR
HYDROLOGY
THE STAGNANT WEATHER PATTERN AND MOISTURE LADEN ATMOSPHERE WILL
LEND ITSELF TO EFFICIENT HEAVY RAINSTORMS AND SCATTERED
THUNDERSTORMS, ESPECIALLY THIS EVENING THROUGH ALL DAY FRIDAY.
MODELS ARE BEGINNING TO FALL IN LINE, SHOWING HEAVY RAINFALL
ACCUMULATIONS MOST LOCATIONS NEAR AND WEST OF MT-HIGHWAY 13. WHEN
THE LOW PRESSURE CIRCULATION STRENGTHENS OVER WYOMING THIS EVENING,
STORM ARE EXPECTED TO RAMP UP.
NEAR AND WEST OF A LINE FROM SCOBEY THROUGH WOLF POINT THROUGH
MCCLOUD, 2-DAY RAINFALL ACCUMULATIONS WILL BE BETWEEN 1 AND 2
INCHES. LOCALLY HIGHER AMOUNTS MAY BE POSSIBLE. NEAR AND EAST OF
THAT LINE, EXPECT LESS THAN 1 INCH OF RAINFALL.
ANYONE PLANNING OUTDOOR ACTIVITIES SHOULD CLOSELY MONITOR THE
LATEST FORECASTS AND ANY POSSIBLE FLOOD WARNING THAT MAY BE
ISSUED. ALTERNATE PLANS WILL NEED TO BE CONSIDERED IN ORDER TO
ADDRESS PUBLIC SAFETY CONCERNS.
----BMICKELSON
GLASGOW WATCHES/WARNINGS/ADVISORIES
FLOOD WATCH THROUGH LATE TONIGHT FOR CENTRAL AND SOUTHEAST
PHILLIPS...CENTRAL AND SOUTHERN VALLEY...DANIELS...GARFIELD...
MCCONE...NORTHERN PHILLIPS...NORTHERN VALLEY...PETROLEUM...
PRAIRIE...SOUTHWEST PHILLIPS...WESTERN ROOSEVELT.
WEATHER.GOV/GLASGOW
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