Area Forecast Discussion
Issued by NWS Glasgow, MT

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000
FXUS65 KGGW 270244
AFDGGW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GLASGOW MT
844 PM MDT TUE MAY 26 2015

.SHORT TERM...FOR NORTHEAST MONTANA...TONIGHT THROUGH THURSDAY...
EVENING UPDATE...ONLY MINOR CHANGES MADE TO POPS TO ACCOUNT FOR
SPATIAL PLACEMENT OF SHOWERS THIS EVENING. INTENSITY HAS DECREASED
IN PAST HOUR OR SO BUT MULTICELLULAR SHOWERS HAVE BEEN PERSISTENT
THROUGH THE EVENING. WEAK UPPER LEVEL FLOW HAS THEM MOVING IN A
WIDE VARIETY OF DIRECTIONS. OTHERWISE NO CHANGES MADE TO THE
FORECAST. SHOULD SEE BETTER INSTABILITY INTO THE DAY WEDNESDAY
PROVIDING A BIT BETTER CHANCE OF SOME THUNDERSHOWERS ACROSS THE
REGION. FRANSEN

...UNSETTLED PERIOD THROUGH THURSDAY...

INSTABILITY CONTINUES TO INCREASE ACROSS THE CWA THIS AFTERNOON.
LAPS INDICATING SBCAPE REACHING 2000 J/KG IN SPOTS SOUTH OF THE
MISSOURI RIVER. WITH THIS MUCH INSTABILITY WOULDN/T BE SURPRISED IF
A REMOTE STORM POPS WITH 1 INCH HAIL BUT LACK OF SHEAR WILL KEEP IT
FROM LASTING TOO LONG THIS AFTERNOON.

UPPER LOW DRIFTING ACROSS THE NORTHERN ROCKIES WILL CONTINUE TO DRAW
MOISTURE INTO THE AREA TONIGHT. AREA OF SHOWERS OVER NORTH-CENTRAL
MONTANA WILL MOVE EAST AND BRING LIKELY CHANCES OF SHOWERS/TSTORMS
WEDNESDAY TO MUCH OF THE CWA. SEVERE STORMS ARE NOT ANTICIPATED BUT
THEY COULD CONTAIN HEAVY RAIN AS PRECIPITABLE WATERS SURPASS 1
INCH...ABOUT 2 STANDARD DEVIATIONS TO NORMAL. NAM AND GFS SEEM TO
HAVE A GOOD HANDLE ON TIMING AND PROGRESSION.

THINGS WIND DOWN A BIT WEDNESDAY NIGHT BUT THE UPPER LOW OVERHEAD
WILL KEEP SCATTERED SHOWERS GOING INTO THURSDAY.

ON THURSDAY...A COLD FRONT APPROACHES THE AREA FROM THE NORTH.
INSTABILITY AHEAD OF THE FRONT WILL KEEP THE THREAT OF SCATTERED
SHOWERS/TSTORMS GOING. TFJ

.LONG TERM...THURSDAY NIGHT THROUGH TUESDAY...

EXTENDED FORECAST PERIOD WILL BE DOMINATED BY THREE RELATIVELY
DISTINCT FEATURES. ONE...CLEARING BEHIND A COLD FRONT FROM THE
NORTH ON THURSDAY NIGHT. THIS WILL ARRIVE COURTESY OF A PASSING
SHORT WAVE TROUGH ATTACHED TO THE HUDSON BAY LOW. IT WILL
BASICALLY ACT TO WEAKEN AND ABSORB THE UPPER-LOW CENTER FROM THE
PACIFIC NORTHWEST AFTER IT MOVES OVER NE MONTANA. WEAK RIDGING
FROM THE WEST AND SOUTHWEST WILL FOLLOW THROUGH SATURDAY MORNING.

TWO...SCATTERED LIGHT SHOWERS AND THUNDERSTORMS LATE SATURDAY
THROUGH MONDAY MORNING. FLOW ALOFT BECOMES ZONAL WITH SLIGHT SHORT
WAVE INFLUENCE FROM THE CANADIAN ROCKIES.

AND THREE...A MUCH MORE ACTIVE PATTERN WITH POSSIBLE HEAVY
RAINFALL AMOUNTS LATE MONDAY NIGHT AND BEYOND. A LARGER-SCALE
UPPER-LEVEL LOW PRESSURE SYSTEM PUSHES INTO THE WESTERN US WITH
STRONGER DYNAMICS AND SUPPORT FOR ORGANIZED HEAVY PRECIP. BMICKELSON

PREVIOUS LONG TERM DISCUSSION...EXTENDED PERIOD OPENS UP WITH
UPPER TROF SWINGING ACROSS THE REGION WITH A BACK DOOR COLD FRONT
DROPPING OUT OF CANADA THURSDAY NIGHT. COOLER TEMPERATURES
EXPECTED ON FRIDAY WITH HIGH PRESSURE PUSHING INTO THE NORTHERN
PLAINS FROM CENTRAL CANADA...ALONG WITH SHOWERS POSSIBLE ALONG THE
FRONTAL BOUNDARY.

HIGH PRESSURE SLIDES EAST ON SATURDAY WITH UPPER RIDGE REBOUNDING
SLIGHTLY OVER THE NORTHERN ROCKIES. TEMPERATURES WILL BEGIN TO
RECOVER WITH THE DEVELOPMENT OF LOW LEVEL SOUTHERLY JET ACROSS THE
HIGH PLAINS. A WEAK WAVE MOVING ACROSS THE CANADIAN ROCKIES ON
SUNDAY...DRAGGING A FRONT THROUGH MONTANA...COULD TRIGGER SOME
ELEVATED THUNDERSTORMS SUNDAY NIGHT BUT MOISTURE NOT VERY
ABUNDANT.

TROF LIFTING INTO THE PACIFIC NORTHWEST EARLY NEXT WEEK LOOKS MORE
FAVORABLE FOR SENDING RAIN INTO NORTHEAST MONTANA. EBERT


&&

.AVIATION...
VFR CONDITIONS ARE EXPECTED OVERNIGHT WITH LIGHT SOUTHEAST WINDS.
SCATTERED SHOWERS AND THUNDERSTORMS COULD PRODUCE MVFR CIGS AND
VSBYS ON WEDNESDAY. MALIAWCO

&&

.GLASGOW WATCHES/WARNINGS/ADVISORIES...NONE.

&&

$$

WEATHER.GOV/GLASGOW





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