Area Forecast Discussion
Issued by NWS Great Falls, MT

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FXUS65 KTFX 280440
AFDTFX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREAT FALLS MT
1035 PM MDT WED MAY 27 2015

AVIATION SECTION UPDATED

.UPDATE...LATEST RADAR IMAGERY SHOWS EARLIER SCATTERED SHOWERS AND
THUNDERSTORMS CONTINUING TO STEADILY DISSIPATE ACROSS THE REGION.
THUS HAVE REDUCED PRECIP CHANCES ACROSS THE REGION BETWEEN NOW AND
MIDNIGHT, THOUGH WILL KEEP ABOUT A 20-30% FOR AREAS ALONG/SOUTH OF A
HELENA-TO-LEWISTOWN LINE AND ALONG THE ROCKY MTN FRONT FOR THE NEXT
COUPLE HOURS. WITH PARTIALLY CLEARING SKIES OVERNIGHT AND THE SPOTTY
AREAS OF RAIN TODAY, HAVE ALSO ADDED IN A POSSIBILITY OF PATCHY FOG
ACROSS ALL COUNTIES THRU 9 AM TOMORROW MORNING.
WARANAUSKAS

&&

.DISCUSSION...

TONIGHT THROUGH FRIDAY...UPPER LOW OVER NORTH CENTRAL IDAHO
CONTINUES TO MOVE SLOWLY SOUTH AND EAST. BAND OF MOISTURE ROTATING
INTO THE STATE FROM THIS FEATURE HELPING TO INITIATE SHOWERS AND
ISOLATED THUNDERSTORMS ACROSS THE AREA. AS HAS BEEN THE CASE ALL
WEEK...SHEAR ALOFT IS VIRTUALLY NONEXISTENT AND STORMS REMAIN
SMALL BUT CAPABLE OF PRODUCING BRIEF HEAVY RAINS. THE LOW OPENS
INTO A BROAD TROF THURSDAY AS IT SWINGS ACROSS THE DIVIDE.
THURSDAY WILL BE ANOTHER UNSETTLED DAY WITH NUMEROUS SHOWERS AND
THUNDERSTORMS OCCURRING THROUGHOUT THE AFTERNOON AND EARLY
EVENING. BY FRIDAY...THE TROF WILL HAVE EXITED THE AREA TO THE
EAST AND WEAK UPPER RIDGING TAKES PLACE. ENOUGH ENERGY AND LOW
LEVEL MOISTURE WILL REMAIN ACROSS THE SOUTH AND SOUTHWEST TO
RESULT IN SCATTERED AFTERNOON SHOWERS AND THUNDERSTORMS.
TEMPERATURES WILL CONTINUE NEAR SEASONAL AVERAGES.

FRIDAY NIGHT THROUGH WEDNESDAY...WEAK RIDGING OVER THE REGION WILL
SUPPORT DRIER AND WARMER WEATHER THROUGH THE REGION...WITH
TEMPERATURES RUNNING ABOUT 5 TO 10 DEGREES ABOVE AVERAGE. MARGINAL
INSTABILITY WILL SUPPORT ISOLATED AFTERNOON THUNDERSHOWERS GENERALLY
OVER HIGHER TERRAIN. A SHORTWAVE TROF PASSING THROUGH WESTERN CANADA
ON SUNDAY WILL DRAG A WEAK COLD FRONT INTO N-CENTRAL MONTANA ON
MONDAY. MOISTURE IS LIMITED WITH THIS FEATURE...AND UPPER LEVEL
RIDGING BEHIND THE SHORTWAVE WILL LIMIT POPS. THE NEXT MORE POTENT
SYSTEM MOVES ACROSS OREGON MONDAY NIGHT. THIS WILL BRING A RETURN TO
WIDESPREAD SHOWERS AND THUNDERSTORMS WHILE DROPPING TEMPERATURES
BACK DOWN A FEW DEGREES BELOW NORMAL FOR TUESDAY AND WEDNESDAY.
NUTTER

&&

.AVIATION... UPDATED 0435Z. SLOW-MOVING UPPER-LEVEL TROUGH WILL KEEP
BROAD AREA OF MOISTURE AND MARGINAL INSTABILITY OVER CENTRAL AND
SOUTHWEST MT NEXT 24 HRS. EARLIER SCATTERED -SHRA AND -TSRA HAVE
ALMOST COMPLETELY DISSIPATED, WITH JUST A FEW WEAKENING SHOWERS TO
LINGER UNTIL 06-08Z FROM KHLN TO KLWT.  EXPECT VFR CONDITIONS
THROUGH THE OVERNIGHT HOURS WITH A MIX OF CLEAR SKIES AND MID-LEVEL
CEILINGS (GENERALLY AT/ABOVE 5000 FT). THERE IS A POSSIBLY OF PATCHY
FOG ACROSS THE REGION TOMORROW MORNING BUT NOT ENOUGH CONFIDENCE ON
LOCATION TO ADD MENTION INTO ANY OF LOCAL TAFS AT THIS TIME.  COLD
FRONT ARRIVING TOMORROW AFTN WILL BRINGER WIDER COVERAGE OF -SHRA
AND -TSRA AND INTERMITTENT MVFR CONDITIONS AT ALL TAF SITES AFTER
18Z. WARANAUSKAS

&&

.PRELIMINARY POINT TEMPS/POPS...
GTF  47  66  45  68 /  40  60  50  30
CTB  43  61  39  67 /  40  60  40  20
HLN  48  66  48  74 /  40  60  60  30
BZN  43  61  44  68 /  40  60  50  30
WEY  35  56  35  62 /  40  50  50  40
DLN  43  63  43  70 /  50  50  50  30
HVR  47  73  38  69 /  40  60  30  10
LWT  46  66  44  64 /  40  60  60  30

&&

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

$$

WEATHER.GOV/GREATFALLS



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