Area Forecast Discussion
Issued by NWS Great Falls, MT

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FXUS65 KTFX 290004
AFDTFX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREAT FALLS MT
600 PM MDT THU MAY 28 2015

.DISCUSSION...
TONIGHT THROUGH SATURDAY...AN UPPER TROUGH FROM NORTHWESTERN WYOMING
THROUGH EASTERN MONTANA THURSDAY AFTERNOON WILL CONTINUE MOVING EAST
AND THE FORECAST AREA WILL FALL UNDER THE INFLUENCE OF AN UPSTREAM
UPPER RIDGE LATER TONIGHT. EXPECT SCATTERED SHOWERS AND A FEW
THUNDERSTORMS EARLY THIS EVENING TO GRADUALLY DIMINISH OVERNIGHT.
NOT SURE HOW MUCH CLEARING WILL GO ON IN THE NORTH BUT HAVE
DECIDED TO MENTION PATCHY FOG FOR LATE TONIGHT AND EARLY FRIDAY
MORNING. THE UPPER RIDGE JUST MENTIONED WILL MOVE OVER THE
FORECAST AREA BY FRIDAY AFTERNOON. THIS WILL LEAD TO LESS SHOWER
AND THUNDERSTORM ACTIVITY THAN ON THURSDAY BUT THERE WILL STILL BE
SOME AFTERNOON INSTABILITY SO WILL CONTINUE THE MENTION OF A
CHANCE OF SHOWERS OR THUNDERSTORMS OVER THE WESTERN MOUNTAINS.
SATURDAY A WEATHER DISTURBANCE ALOFT WILL MOVE TO CENTRAL MONTANA
BY LATE AFTERNOON. THIS DISTURBANCE COMBINED WITH GENERALLY
GREATER INSTABILITY WILL RESULT IN AN INCREASE IN SHOWER AND
THUNDERSTORM ACTIVITY. IN FACT THE ENVIRONMENT OVER CENTRAL
MONTANA AND TO A LESSER EXTENT OVER SOUTHWEST MONTANA LOOKS
FAVORABLE FOR STRONGER BUT NOT NECESSARILY SEVERE THUNDERSTORMS.
BLANK

SATURDAY NIGHT THROUGH WEDNESDAY...A WESTERLY FLOW ALOFT OVER
MONTANA THIS WEEKEND RESULTS AS A GRADIENT BETWEEN A WESTERN
CANADIAN TROUGH AND AN GREAT BASIN RIDGE. MINOR IMPULSES IN THIS
FLOW...COMBINED WITH SURFACE DEWPOINTS IN THE UPPER 40S AND A NEARLY
LINEAR SHEAR PROFILE WILL MAINTAIN SCATTERED SHOWERS AND
THUNDERSTORMS SATURDAY NIGHT. WEAK RIDGING ALOFT ON SUNDAY WILL
SUPPRESS ALL BUT ISOLATED AFTERNOON SHOWERS AS THE UPPER LEVEL FLOW
TURNS MORE SOUTHWESTERLY. WIDESPREAD THUNDERSTORMS ARE INDICATED
MONDAY AFTERNOON WITH A CLOSED UPPER TROUGH APPROACHING FROM THE
PACIFIC. AN ACCOMPANYING SURFACE LOW FORMING IN SOUTHEAST MONTANA
WILL SUPPORT A HUMID EASTERLY FLOW OVER THE NORTH CENTRAL PLAINS.
DIVERGENT SOUTHWEST FLOW ALOFT WILL YIELD AN INCREASINGLY UNSTABLE
ENVIRONMENT. CONVECTIVE PARAMETERS DO NOT SUPPORT SEVERE STORMS...
BUT THE SETUP DOES WARRANT ATTENTION FOR A FEW STRONGER STORMS
INCLUDING SMALL HAIL AND GUSTY WINDS. TIMING WILL BECOME AN
IMPORTANT FACTOR TO CONSIDER. THE WAVE OPENS ON TUESDAY AND
WEDNESDAY AS DIFFERENCES BEGIN TO APPEAR AMONG MODEL SOLUTIONS.
HOWEVER THE OVERALL PATTERN REMAINS UNSETTLED THROUGH THE PERIOD
WITH CONTINUING SHOWERS AND ISOLATED THUNDERSTORMS. TEMPERATURES
TREND BELOW NORMAL THROUGH MIDWEEK. SNOW LEVELS COULD LOWER TO
AROUND 7500 FT MSL WEDNESDAY MORNING ALONG THE CONTINENTAL
DIVIDE...BUT AS YET VERY LITTLE CONFIDENCE IN THE POTENTIAL FOR ANY
ACCUMULATION. NUTTER

&&

.AVIATION...
UPDATED 1730Z.

A QUICK MOVING COLD FRONT IS TRAVELING SOUTH OVER THE AREA AT THIS
TIME CREATING QUICKLY CHANGING WEATHER CONDITIONS AS SHOWERS AND
THUNDERSTORMS DEVELOP ON THE WARM SIDE OF THE FRONT, AND FOG WITH
LOW CEILINGS MOVE IN POST FRONTAL PASSAGE ESPECIALLY NEAR THE ROCKY
MOUNTAIN FRONT. AS THE SHOWERS DECREASE IN INTENSITY THIS EVENING
THUNDERSTORMS SHOULD BECOME LESS COMMON GOING INTO THE OVERNIGHT
HOURS. CONDITIONS WILL BE GENERALLY IMPROVING POST FRONTAL PASSAGE
BUT REDUCTIONS IN FLIGHT CATEGORIES COULD LAST FOR THE NEXT FEW
HOURS AT LEAST FOR KCTB AND KGTF. CONDITIONS SHOULD IMPROVE TO
WIDESPREAD VFR BY MID MORNING ON FRIDAY. SUK

&&

.PRELIMINARY POINT TEMPS/POPS...
GTF  44  70  50  73 /  50  20  10  50
CTB  40  67  43  71 /  10  20  20  50
HLN  47  74  51  75 /  60  20  20  40
BZN  44  68  47  71 /  60  20  20  40
WEY  35  63  39  65 /  50  30  20  30
DLN  44  70  48  72 /  40  20  30  50
HVR  38  69  45  76 /  10  10  10  30
LWT  42  65  47  73 /  80  20  10  60

&&

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

$$

WEATHER.GOV/GREATFALLS



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