Area Forecast Discussion
Issued by NWS Great Falls, MT

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FXUS65 KTFX 032042
AFDTFX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREAT FALLS MT
242 PM MDT SUN MAY 3 2015

.DISCUSSION...

TONIGHT THROUGH TUESDAY...ZONAL FLOW ALOFT WILL CONTINUE
OVERNIGHT. DOWNSLOPE EFFECTS WILL CONTINUE TO KEEP THE PLAINS DRY.
MOISTURE OVER SOUTHWEST MONTANA AND A SLIGHTLY UNSTABLE AIRMASS
WILL KEEP THE POSSIBILITY OF AN EVENING THUNDERSTORM ALIVE. AS A
STRONG UPPER TROF APPROACHES THE WEST COAST MONDAY, THE FLOW ALOFT
BECOMES INCREASINGLY SOUTHWEST ALLOWING MOISTURE AND INSTABILITY
TO BEGIN TO INCREASE OVER THE AREA. SCATTERED THUNDERSTORMS WILL
LIKELY FORM OVER SOUTHWEST MONTANA MONDAY AFTERNOON AND SPREAD
NORTH AND EAST AS FAR AS THE LITTLE BELT MOUNTAINS. THE UPPER TROF
MOVES ACROSS THE PACIFIC NORTHWEST ON TUESDAY. THE RESULTING
DIFFLUENT SOUTHWEST FLOW ALOFT WILL ALLOW THUNDERSTORMS TO DEVELOP
DURING THE AFTERNOON WITH AN AREAL COVERAGE GREATER THAN MONDAY`S.
HIGH TEMPERATURES BOTH DAYS WILL REMAIN SOME 12 TO 15 DEGREES
ABOVE SEASONAL AVERAGES.

TUESDAY NIGHT THROUGH SUNDAY...MEDIUM RANGE FORECAST MODELS
CONTINUE TO BE IN GENERAL AGREEMENT FOR MUCH OF THE FORECAST PERIOD.
HOWEVER, CONFIDENCE IN TIMING, LOCATION AND AMOUNTS OF PRECIPITATION
REMAINS LOWER THAN I WOULD PREFER. MAIN PLAYER IN THE FORECAST
EVOLUTION IS AN UPPER LEVEL LOW THAT MOVES SOUTHWARD FROM THE
PACIFIC NORTHWEST TO THE CENTRAL CALIFORNIA COAST BETWEEN TUESDAY
NIGHT AND FRIDAY. THIS SYSTEM THEN EVOLVES INTO AN OPEN WAVE AND
MOVES EAST-NORTHEAST INTO THE NORTHERN PLAINS BY SUNDAY. THIS
PATTERN CONTINUES TO LOOK FAVORABLE FOR COOL AND UNSETTLED SPRING
WEATHER THROUGH THE ENTIRE TIME PERIOD. AM CONTINUING TO BROAD-BRUSH
SCATTERED TO NUMEROUS SHOWERS ACROSS MUCH OF THE AREA BUT CONFIDENCE
IN ANY TYPE OF A WIDESPREAD WETTING RAIN REMAINS ELUSIVE. MPJ

&&

.AVIATION...
UPDATED 17410Z.
HIGH PRESSURE ALOFT WILL PROVIDE DRY AND STABLE
CONDITIONS. THE EXCEPTION BEING SOUTHWEST MONTANA WHERE THE AIRMASS
IS SOMEWHAT UNSTABLE AND ISOLATED CONVECTIVE ACTIVITY IS POSSIBLE
FROM 21Z THROUGH 03Z. VFR CONDITIONS PREVAIL WITH POSSIBLE MVFR
CONDITIONS IN THE VICINITY OF SHOWERS AND/OR THUNDERSTORMS.

&&

.PRELIMINARY POINT TEMPS/POPS...
GTF  39  76  45  76 /   0  10  10  30
CTB  31  72  40  70 /   0  10  10  20
HLN  39  77  44  76 /  10  10  10  30
BZN  37  73  42  73 /  10  20  10  30
WEY  27  68  34  68 /  20  30  20  30
DLN  38  74  43  71 /  10  20  20  30
HVR  34  76  41  79 /   0  10  10  30
LWT  37  73  45  75 /  10  10  20  30

&&

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

$$

WEATHER.GOV/GREATFALLS


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