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.  
 
 
 
 
 
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