Area Forecast Discussion
Issued by NWS Great Falls, MT

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FXUS65 KTFX 030532
AFDTFX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREAT FALLS MT
1125 PM MDT TUE JUN 2 2015

UPDATED AVIATION SECTION

.DISCUSSION...
UPDATE FORTHCOMING. WET SPRING PATTERN WILL CONTINUE INTO MIDWEEK.
HAVE LOWERED POPS A BIT FOR THE REMAINDER OF THE EVENING.
HOWEVER...RADAR RETURNS CONTINUE TO SHOW SMALL AREAS OF RAIN
DEVELOPING ACROSS THE AREA. AN ISOLATED THUNDERSTORM CANNOT BE RULED
OUT AS WELL. SLIGHT CHANCE POPS WILL BE THE RULE AFTER MIDNIGHT.
SHOWERS AND THUNDERSTORMS DEVELOP AGAIN WEDNESDAY AFTERNOON.
TEMPERATURES LOOK REASONABLE.

&&

.AVIATION...
UPDATED 0525Z.

VFR CONDITIONS WILL MOSTLY CONTINUE ACROSS THE FORECAST AREA THROUGH
AT LEAST WEDNESDAY EVENING, BUT BRIEF MVFR CONDITIONS ARE POSSIBLE
WITH SHOWERS AND STORMS THROUGH THE PERIOD. THE MOIST SOUTHWESTERLY
FLOW ALOFT WILL PERSIST OVER THE AREA. A DISTURBANCE IN THE FLOW
WILL KEEP SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS ACROSS THE
AREA THROUGH AROUND 10Z, AS THE AIRMASS STABILIZES. ANOTHER WEAK
DISTURBANCE WILL THEN INITIATE A FEW SHOWERS/STORMS BY 18Z, MAINLY
NEAR THE MOUNTAINS. A THIRD STRONGER DISTURBANCE WILL THEN BRING
INCREASED COVERAGE OF SHOWERS/THUNDERSTORMS, ESPECIALLY ALONG AND
SOUTH OF A KHLN-KHVR LINE, ALONG WITH A BETTER CHANCE OF MOUNTAIN
OBSCURATION AFTER 21Z. THESE STORMS COULD PERSIST BEYOND 06Z IN THE
EASTERN TERMINAL AREAS (KHVR KLWT).  COULSTON

&&

.PREV DISCUSSION...ISSUED 202 PM MDT TUE JUN 2 2015

TONIGHT THROUGH THURSDAY...MONTANA WILL REMAIN BENEATH A MOIST AND
SOMEWHAT UNSTABLE SOUTHWEST FLOW ALOFT THROUGH THURSDAY. SCATTERED
TO NUMEROUS SHOWERS AND THUNDERSTORMS CAN BE EXPECTED AGAIN THIS
AFTERNOON AND EVENING. HOWEVER, CAPE AND SHEAR ARE JUST LOW
ENOUGH TO INHIBIT ANY STRONG STORMS FROM FORMING. THERE WILL BE A
SHORT BREAK IN SHOWER ACTIVITY LATE TONIGHT THROUGH WEDNESDAY
MORNING BUT THE ATMOSPHERE WILL DESTABILIZE ONCE AGAIN WEDNESDAY
AFTERNOON. CONVECTION IS EXPECTED TO DEVELOP OVER WESTERN AND
SOUTHWEST MONTANA DURING THE EARLY TO MID AFTERNOON THEN WILL
MOVE INTO CENTRAL MONTANA DURING THE LATE AFTERNOON AND EVENING
HOURS. MODELS ALSO SUGGEST THAT A LOBE OF VORTICITY WILL BE
EJECTED FROM THE MAIN LOW OVER THE PACIFIC NORTHWEST AND TRACK
ACROSS CENTRAL MONTANA LATE WEDNESDAY NIGHT. THIS DEVELOPMENT WILL
KEEP WIDESPREAD SHOWERS AND SCATTERED THUNDERSTORMS IN PLACE
ACROSS EASTERN PORTIONS OF CENTRAL MONTANA THROUGH THURSDAY
MORNING BEFORE THE VORTICITY LOBE MOVES INTO CANADA. RESIDUAL
MOISTURE WILL COMBINE WITH DAYTIME HEATING FOR ANOTHER ROUND OF
SCATTERED SHOWERS AND THUNDERSTORMS THURSDAY AFTERNOON.
TEMPERATURES THROUGH THE SHORT TERM WILL REMAIN NEAR OR SLIGHTLY
BELOW SEASONAL AVERAGES AND WINDS WILL REMAIN GENERALLY LIGHT. MPJ

THURSDAY NIGHT THROUGH MONDAY...MEDIUM RANGE MODELS ARE IN VERY GOOD
AGREEMENT WITH THE OVERALL PATTERN. AN UPPER LEVEL TROUGH OF LOW
PRESSURE WILL REMAIN OVER THE WESTERN UNITED STATES THROUGH THE
PERIOD WITH ITS LOW PRESSURE CENTER INITIALLY STAYING OVER THE
CALIFORNIA COAST. THE CHANCE FOR SHOWERS/THUNDERSTORMS WILL DECREASE
THURSDAY NIGHT AS A SHORTWAVE TROUGH EXITS THE AREA. ANOTHER
SHORTWAVE WILL EJECT FROM THE TROUGH AND BRING A GOOD CHANCE OF
SHOWERS AND THUNDERSTORMS TO THE AREA AGAIN FOR FRIDAY AFTERNOON AND
EVENING. THE LOW PRESSURE CENTER WILL THEN MOVE NORTH INTO THE
WESTERN GREAT BASIN FOR SATURDAY THROUGH SUNDAY. THIS WILL KEEP A
GOOD CHANCE OF SHOWERS AND THUNDERSTORMS OVER SOUTHWEST MONTANA, BUT
WEAK HIGH PRESSURE TO THE NORTH OF THIS LOW WILL HINDER SHOWER AND
THUNDERSTORM DEVELOPMENT ACROSS NORTH CENTRAL MONTANA. THE LOW WILL
THEN WEAKEN AS IT MOVES NORTH INTO THE NORTHERN ROCKIES ON MONDAY,
BUT WITH IT MOVING OVERHEAD, THERE WILL BE A GOOD CHANCE FOR SHOWERS
AND THUNDERSTORMS FOR THE ENTIRE FORECAST AREA. TEMPERATURES WILL
REMAIN FAIRLY CONSTANT THROUGH THE PERIOD. HIGHS WILL BE NEAR NORMAL
(UPPER 60S TO LOWER 70S), BUT LOWS WILL BE QUITE MILD (MID 40S TO
LOWER 50S), REMAINING 5 TO 10 DEGREES WARMER THAN NORMAL.
COULSTON

&&

.PRELIMINARY POINT TEMPS/POPS...
GTF  45  67  49  66 /  50  40  50  40
CTB  41  65  44  65 /  60  20  30  40
HLN  48  69  49  71 /  40  40  50  30
BZN  43  68  45  69 /  50  30  40  30
WEY  36  63  38  63 /  30  30  40  30
DLN  42  66  45  67 /  40  40  50  40
HVR  46  69  48  68 /  60  30  50  70
LWT  44  65  49  65 /  50  40  60  60

&&

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

&&

$$

WEATHER.GOV/GREATFALLS



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