Area Forecast Discussion
Issued by NWS Great Falls, MT

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FXUS65 KTFX 022057
AFDTFX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREAT FALLS MT
257 PM MDT SAT MAY 2 2015

.DISCUSSION...

TONIGHT THROUGH MONDAY...WEAK COLD FRONT CONTINUES TO PUSH SLOWLY
SOUTH THIS AFTERNOON. FRONT HAS GONE THROUGH GREAT FALLS WITH
WINDS SHIFTING TO THE NORTHWEST. WINDS WILL EVENTUALLY SHIFT TO
THE NORTHEAST LATER TONIGHT. VERY LITTLE MOISTURE IS ASSOCIATED
WITH THIS FRONT. 12Z SOUNDING INDICATING A VERY DRY LOWER
ATMOSPHERE. THE EXCEPTION IS SOUTHWEST MONTANA WHERE THE AIRMASS
IS A BIT MORE UNSTABLE AND ISOLATED SHOWERS REMAIN A POSSIBILITY
THROUGH THIS EVENING. DRY WESTERLY FLOW ALOFT CONTINUES SUNDAY.
ISOLATED AFTERNOON AND EVENING THUNDERSTORMS ARE POSSIBLE SUNDAY.
500 MB HEIGHTS RISE ON MONDAY AND THE FLOW ALOFT BECOMES SOUTHWEST
AS AN UPPER TROF APPROACHES THE WEST COAST. THIS WILL ALLOW FOR
WARMER AIR TO RETURN. AS WAS THE CASE OVER THE WEEKEND, ISOLATED
THUNDERSTORMS MONDAY WILL BE CONFINED TO SOUTHWEST MONTANA.
TEMPERATURES WILL CONTINUE ABOVE SEASONAL AVERAGES.

MONDAY NIGHT THROUGH SATURDAY...MEDIUM RANGE FORECAST MODELS ARE IN
MUCH BETTER AGREEMENT TONIGHT AS THE ECMWF HAS TRENDED TOWARD THE
GFS SOLUTION. MAIN CHALLENGE CONTINUES TO BE THE EVOLUTION OF AN
UPPER LEVEL LOW THAT STARTS OFF THE PERIOD ALONG THE SOUTHERN
BRITISH COLUMBIA COAST. MODELS ARE NOT IN COMPLETE AGREEMENT BUT
THEY BOTH MOVE THIS SYSTEM INLAND OVER THE PACIFIC NORTHWEST AND
THEN SOUTHWARD THROUGH CALIFORNIA BEFORE HOOKING EASTWARD INTO
NEVADA BY THE END OF THE WEEK. TUESDAY IS EXPECTED TO BE THE WARMEST
DAY OF THE WEEK WITH HIGH TEMPERATURES ABOUT 10 DEGREES ABOVE
SEASONAL AVERAGE. HIGH TEMPERATURES COOL OFF BY 10 TO 15 DEGREES
EACH DAY THROUGH THURSDAY WITH HIGHS ON THURSDAY TOPPING OUT IN THE
MID 40S TO MID 50S. SCATTERED SHOWERS AND A FEW THUNDERSTORMS WILL
BE CONFINED TO SOUTHWEST MONTANA MONDAY EVENING BUT WILL LIKELY
SPREAD ACROSS MUCH OF THE FORECAST AREA TUESDAY THROUGH THURSDAY.
THERE IS ALSO A POSSIBILITY THAT WIDESPREAD WETTING RAINS COULD
DEVELOP WEDNESDAY NIGHT AND THURSDAY BUT WILL HOLD OFF ON ADDING
THIS TO THE FORECAST AT THIS TIME AND WILL WAIT TO SEE WHAT MODELS
DO IN THE COMING 24 HOURS OR SO. MODELS SUGGEST THAT THE UPPER LOW
WILL WEAKEN INTO AN OPEN WAVE AND BEGIN TO LIFT TO THE NORTHEAST
KEEPING UNSETTLED CONDITIONS BUT NOT AS COOL CONDITIONS IN THE
FORECAST THROUGH NEXT WEEKEND. MPJ


&&

.AVIATION...
UPDATED 1755Z.
WEAK CANADIAN COLD FRONT CONTINUES TO PUSH SLOWLY SOUTH ACROSS THE
AREA. PASSAGE OF COLD FRONT WILL BE DRY WITH THE WINDS SHIFTING TO
THE NORTHWEST AND THEN THE NORTH BEHIND THE FRONT. WINDS MAY BE
GUSTY FOR A FEW HOURS BEHIND THE FRONT. VFR CONDITIONS PREVAIL.

&&

.PRELIMINARY POINT TEMPS/POPS...
GTF  35  65  39  75 /  10  10  10  10
CTB  30  61  33  72 /  10  10  10  10
HLN  36  70  39  75 /  10  10  10  10
BZN  35  67  37  72 /  10  10  10  20
WEY  29  66  29  67 /  20  30  20  20
DLN  38  69  40  72 /  10  20  10  20
HVR  33  64  35  76 /  10  10  10  10
LWT  34  63  38  72 /  10  10  10  10

&&

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

$$

WEATHER.GOV/GREATFALLS



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