Area Forecast Discussion
Issued by NWS Glasgow, MT

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000
FXUS65 KGGW 221501
AFDGGW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GLASGOW MT
901 AM MDT MON SEP 22 2014

.SHORT TERM...FOR NORTHEAST MONTANA...TODAY THROUGH WEDNESDAY...
UPPER LOW SPINNING INTO WYOMING SPREADING CLOUDS INTO SOUTHERN
MONTANA THIS MORNING. THESE CLOUDS EXPECTED TO SKIRT THE SOUTHERN
PORTION OF THE CWA AS THE LOW TRACK EAST TODAY AND TONIGHT.
OTHERWISE UPPER RIDGE OVER CENTRAL CANADA WILL KEEP SKIES SUNNY
WITH WARM TEMPERATURES. UPDATE ONLY TO ADJUST SKY COVER ACROSS
SOUTHERN PETROLEUM COUNTY. EBERT

PREVIOUS SHORT TERM DISCUSSION...THE DAY BEGINS WITH NORTHEAST
MONTANA UNDER A LONG- WAVE RIDGE AXIS. TO THE SOUTH IN WYOMING AND
SOUTHERN IDAHO AN UNDERCUTTING OPEN TROUGH BEGINS TO MOVE EAST. BY
ITS MOVEMENT THE TROUGH ENERGY WILL REMAIN WELL TO OUR SOUTH. THE
MAIN EFFECT WILL BE SOME MID TO HIGH CLOUDS SPREADING NORTH INTO
NEMONT TODAY. SO THE MAIN INFLUENCE ON THE LOCAL WEATHER WILL BE
THE CONTINUED HIGH PRESSURE. THE RESULT WILL BE WARMING
TEMPERATURES. HIGHS TODAY SHOULD RISE 5F TO 10F WARMER THAN
SUNDAY. THE LIGHT SOUTHERLY BREEZE WILL ALSO CONTINUE.

BY TUESDAY THE TROUGH WILL HAVE MOVED FULLY INTO THE DAKOTAS AND
FLOW ALOFT LOCALLY WILL BECOME WESTERLY. TEMPERATURES WILL ONLY
SLIGHTLY WARM OVER MONDAY.

A CHANGE COMES ABOUT ON WEDNESDAY WHEN A DEEP TROUGH ESTABLISHES
ITSELF OFF THEN WEST COAST. THIS WILL QUICKLY BUILD UP AN
AMPLIFIED TROUGH WITH ITS AXIS CENTERED OVER NEMONT BY 00Z
THURSDAY. THIS COULD VERY WELL GENERATE THE WARMEST DAY OF THE
SHORT TERM PERIOD WITH HIGHS APPROACHING 90F DEGREES. SCT

.LONG TERM...WEDNESDAY NIGHT THROUGH MONDAY...
UPPER RIDGE WILL PREVAIL OVER MONTANA WEDNESDAY NIGHT AND THURSDAY AS
FLOW ALOFT BECOMES INCREASINGLY AMPLIFIED WITH DIGGING UPPER
TROUGH ON WEST COAST. THIS WILL BRING WARM AND DRY WEATHER TO THE
FORECAST AREA. 850 MB TEMPS OF 24-26C ON THURSDAY WOULD YIELD
HIGHS IN THE MID TO UPPER 90S IF FULL MIXING OCCURS. HOWEVER...
WITH ONLY 12 HOURS OF DAYLIGHT AND SE WINDS...ATMOSPHERE MAY NOT
FULLY MIX ESPECIALLY IF A STRONG LOW LEVEL INVERSION FORMS AT
NIGHT. ATMOSPHERE DID NOT FULLY MIX IN A SIMILAR PATTERN LAST
THURSDAY. WILL USE THE COOLER ECMWF GUIDANCE WHICH HAS HIGHS
AROUND 90 FOR THURSDAY.

RIDGE NUDGES FAR ENOUGH EAST ON FRIDAY TO PUT THE FORECAST AREA IN
SW FLOW ALOFT AS UPPER TROUGH ON THE WEST COAST DIGS INTO
CALIFORNIA. IT STILL LOOKS WARM AND DRY FOR EASTERN MONTANA
ALTHOUGH NOT AS WARM AS THURSDAY AS MODELS BRING A WEAK COLD FRONT
INTO THE AREA.

THIS COLD FRONT BECOMES QUASI-STATIONARY OVER EASTERN MONTANA ON
SATURDAY AS CUT OFF LOW FORMS OVER EITHER CALIFORNIA (ECMWF) OR
NEVADA (GFS) AND THE FRONT BECOME PARALLEL TO THE SW FLOW ALOFT.
THERE MAY BE ENOUGH MOISTURE ALONG THIS FRONT FOR A CHANCE OR SLIGHT
CHANCE OF SHOWERS AND THUNDERSTORMS.

THIS FRONT WILL MOVE SLOWLY EAST SATURDAY NIGHT AND SUNDAY AS CUT
OFF LOW REMAINS TO THE SW OF THE FORECAST AREA. MODELS DIFFER ON
HOW TO MOVE THIS LOW TO THE EAST OR NORTHEAST EARLY NEXT WEEK.
WILL MAINTAIN A CHANCE OR SLIGHT CHANCE OF SHOWERS AND
THUNDERSTORMS FOR NOW. FORRESTER


&&

.AVIATION...
FLIGHT CATEGORY: VFR.

SYNOPSIS: MOSTLY CLEAR SKIES AS HIGH PRESSURE MOVES SLOWLY TO THE EAST.

AREA WINDS: OUT OF THE EAST TO SOUTHEAST AT 5 TO 15 KTS.

EQUIPMENT: KGDV AWOS OBSERVATION INSTRUMENT HAS BEEN DOWN FOR THE
WEEKEND AND THEREFORE WILL CONTINUE WITH... AMD NOT SKED.

GAH

&&

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

&&

$$

WEATHER.GOV/GLASGOW




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