Area Forecast Discussion
Issued by NWS Great Falls, MT

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FXUS65 KTFX 221750
AFDTFX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREAT FALLS MT
1150 AM MDT WED APR 22 2015

TODAY...A LOW PRESSURE SYSTEM IS APPROACHING THE ROCKIES AND THE
AIRMASS WILL BECOME UNSTABLE THIS AFTERNOON WITH A CHANCE OF
AFTERNOON SHOWERS AND THUNDERSTORMS. UPDATED TO FRESHEN POPS AND WX.
ZELZER


.DISCUSSION...
WEDNESDAY THROUGH FRIDAY...A MORE DYNAMIC CONVECTIVE WEATHER
PATTERN WILL BEGIN IN EARNEST THIS AFTERNOON AND EVENING AS THE
HIGH PRESSURE RIDGE THAT HAS BEEN RESPONSIBLE FOR THE DRIER AND
WARMER CONDITIONS YIELDS TO A QUICK MOVING COLD FRONT AND
ASSOCIATED LOW PRESSURE SYSTEM. MODELS CONTINUE TO SLOW DOWN THE
TIMING OF THE COLD FRONT MOVING ACROSS THE AREA...HOWEVER
INSTABILITY AHEAD OF THE FRONT SHOULD ALLOW FOR LATE AFTERNOON AND
EVENING SHOWERS TO DEVELOP WITH ENOUGH INSTABILITY TO ALLOW FOR
SOME THUNDERSTORMS WITH THE BEST CHANCES OVER THE HIGHER TERRAIN.
AFTER THE SYSTEM EXITS OUT OF THE AREA THURSDAY SOUTHWEST FLOW
ALOFT WILL ALLOW FOR DAYTIME HEATING TO CONTINUE TO PRODUCE
SHOWERS AND THUNDERSTORMS IN THE AFTERNOON AND EVENING ON THURSDAY
AND FRIDAY. THE LACK OF MOISTURE ALOFT WILL CONTINUE TO BE THE
LIMITING FACTOR IN THIS SCENARIO. SUK

FRIDAY NIGHT THROUGH WEDNESDAY....THE MEDIUM RANGE PERIOD BEGINS ON
AN UNSETTLED NOTE AS AN UPPER TROF PUSHES INTO THE PACIFIC NORTHWEST
AND THE SUBSEQUENT SOUTHWEST FLOW ALOFT AHEAD OF THE TROF WILL BRING
MOISTURE AND INSTABILITY TO SOUTHWEST AND CENTRAL MONTANA FRIDAY
NIGHT AND SATURDAY. THE TROF WEAKENS SUNDAY AS ITS AXIS CROSSES THE
CONTINENTAL DIVIDE. SHOWERS SUNDAY WILL BE CONFINED MAINLY TO
SOUTHWEST AND SOUTHERN MONTANA. AN UPPER RIDGE BEGINS TO BUILD INTO
WESTERN MONTANA MONDAY AND HERALDS THE BEGINNING OF A DRY...STABLE
AND FAIRLY QUIET WEATHER PATTERN. THE RIDGE AXIS WILL REACH THE
CONTINENTAL DIVIDE ON WEDNESDAY. TEMPERATURES WILL BE NEAR TO
SLIGHTLY ABOVE SEASONAL AVERAGES THROUGH THE WEEKEND AND WILL THEN
CLIMB ABOVE SEASONAL AVERAGES TO START THE NEW WEEK.

&&

.AVIATION...UPDATED 1745Z.

AN UPPER LEVEL LOW PRESSURE SYSTEM IS APPROACHING THE ROCKIES AND
THE AIRMASS OVER CENTRAL AND SOUTHWEST MONTANA WILL BECOME UNSTABLE
THIS AFTERNOON. SCATTERED SHOWERS AND THUNDERSTORMS WILL DEVELOP
DURING THE AFTERNOON. A COLD FRONT WILL MOVE THROUGH THE REGION THIS
EVENING AND AREAS OF PRECIPITATION WILL CONTINUE BEHIND THE FRONT.
LOCAL MVFR CONDITIONS ARE POSSIBLE NEAR SHOWERS AND
THUNDERSTORMS...ELSEWHERE VFR CONDITIONS WILL PREVAIL.

&&

.PRELIMINARY POINT TEMPS/POPS...
GTF  70  42  61  41 /  10  40   0  10
CTB  67  35  58  40 /  10  30   0  10
HLN  70  37  61  37 /  20  50  10  10
BZN  69  40  61  37 /  20  50  30  20
WEY  58  32  54  30 /  20  10  30  20
DLN  66  38  61  35 /  20  50  20  10
HVR  70  45  62  42 /  10  70  20  10
LWT  65  42  57  39 /  10  40  20  10

&&

.TFX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

$$

WEATHER.GOV/GREATFALLS



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