Area Forecast Discussion
Issued by NWS Great Falls, MT

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FXUS65 KTFX 251146
AFDTFX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREAT FALLS MT
546 AM MDT MON MAY 25 2015

...UPDATE TO AVIATION...

.DISCUSSION...

TODAY THROUGH WEDNESDAY...FAIR AND COOL WEATHER ACROSS THE ZONES
THIS MORNING AS WE ARE LOCATED BETWEEN TWO SLOW-MOVING WEATHER
SYSTEMS. PATCHY FOG MAY DEVELOP AROUND SUNRISE...BUT NOT EXPECTED TO
BE AS WIDESPREAD AS OCCURRED SUNDAY MORNING. EXPECT MOSTLY SUNNY AND
WARMER CONDITIONS TODAY...BUT WITH INCREASING CHANCES FOR SHOWERS
AND THUNDERSTORMS BY LATE AFTERNOON AS THE ENVIRONMENT BECOMES MORE
UNSTABLE. THIS ACTIVITY WILL GRADUALLY INCREASE IN COVERAGE MONDAY
NIGHT AS A RATHER SUBSTANTIAL PACIFIC TROUGH MOVES CLOSER TO THE
AREA. PRIMARY MODELS ALL SUGGEST A BAND OF MODERATE SHOWERS WILL
LIFT NORTHWARD THROUGH THE ZONES STARTING TUESDAY MORNING. GIVEN A
WARMER AND MOIST EASTERLY FLOW WITH INCREASING SHEAR OVER N-CENTRAL
MONTANA...SOME STORMS COULD BECOME A BIT STRONGER TUESDAY AFTERNOON.
ENVIRONMENTAL INDICES DO NOT SUGGEST SEVERE THUNDERSTORMS...BUT
SMALL HAIL AND GUSTY WINDS WILL BE POSSIBLE. AREAS OF RAIN WILL
CONTINUE TUESDAY NIGHT THROUGH WEDNESDAY AS THE UPPER LOW BECOMES
NEARLY STATIONARY OVER NORTHERN IDAHO. DIFFERENCES BEGIN TO APPEAR
IN THE MODEL SOLUTIONS ON WEDNESDAY AS TO WHETHER THE UPPER LOW
REMAINS CLOSED OFF OR TRANSITIONS TO AN OPEN WAVE. DESPITE LOWER
CONFIDENCE IN LOCATION AND TIMING...IT DOES APPEAR PRECIPITATION
CONTINUING ON WEDNESDAY WILL BE MORE STRATIFORM IN NATURE WITH ONLY
ISOLATED THUNDERSTORMS. 48-HOUR TOTAL RAINFALL FROM TUESDAY MORNING
THROUGH THURSDAY MORNING RANGES FROM AROUND 0.3 INCHES OVER THE
NORTHERN ZONES...WITH OVER 0.75 INCHES IN MOUNTAIN ARES. UP TO 0.5
INCHES WILL BE POSSIBLE ALONG THE ROCKY MOUNTAIN FRONT. WILL NEED
WATCH FOR TEMPORARY RISES ON SMALL MOUNTAIN STREAMS. NUTTER

WEDNESDAY NIGHT THROUGH MONDAY...MEDIUM RANGE PERIOD STARTS OUT
WITH AN UPPER LEVEL TROUGH OVER THE NORTHERN ROCKIES AND UNSETTLED
CONDITIONS ACROSS THE FORECAST AREA. MODEL SOLUTIONS DIVERGE A
BIT FOR THE THURSDAY NIGHT THROUGH FRIDAY NIGHT PERIOD BUT
CONVERGE ONCE AGAIN BY SATURDAY. FOR THE REMAINDER OF THE WEEKEND
THROUGH EARLY NEXT WEEK THE FORECAST AREA WILL REMAIN BENEATH A
WESTERLY FLOW ALOFT WITH RIDGING TO THE SOUTH AND A DISTURBANCE
OVER WESTERN CANADA. FOR MUCH OF THE FRIDAY THROUGH MONDAY TIME
FRAME IT APPEARS THAT DIURNAL SHOWERS AND THUNDERSTORMS WILL
APPEAR EACH DAY AND TEMPERATURES WILL BE ABOVE SEASONAL AVERAGES.
AM NOT EXPECTING ANY WIDESPREAD OR SIGNIFICANT WEATHER SYSTEMS
AND IT APPEARS THAT STRONG TO SEVERE THUNDERSTORMS WILL NOT BE
LIKELY. MPJ

&&

.AVIATION...
UPDATED 1146Z.

UPPER LEVEL LOW CONTINUES TO SPIN OVER THE PACIFIC NORTHWEST THROUGH
EARLY TUESDAY MORNING. SCATTERED MID AND HIGH LEVEL CLOUDS FOR
WIDESPREAD VFR CONDITIONS THIS MORNING EXCEPT FOR LOCAL LIFR/IFR
CONDITIONS DUE TO PATCHY FOG IN SOUTHWEST MONTANA VALLEYS. CLOUDS
INCREASE IN COVERAGE TODAY WITH SCATTERED SHOWERS AND THUNDERSTORMS
DEVELOPING BY 20Z. MOSTLY CLOUDY CONDITIONS AND SCATTERED SHOWERS
CONTINUE OVERNIGHT FOR MVFR/VFR CEILINGS. MOUNTAINS OBSCURED AT
TIMES AFTER 02Z TUESDAY. MPJ

&&

.PRELIMINARY POINT TEMPS/POPS...
GTF  70  49  69  47 /  20  50  70  40
CTB  70  45  66  43 /  20  50  70  50
HLN  72  49  70  50 /  30  60  50  50
BZN  67  45  67  46 /  30  30  50  50
WEY  60  38  58  36 /  50  40  50  50
DLN  68  44  66  44 /  20  50  60  60
HVR  76  47  73  46 /  10  20  40  30
LWT  67  46  67  48 /  40  20  60  40

&&

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

$$

WEATHER.GOV/GREATFALLS



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