Area Forecast Discussion
Issued by NWS Great Falls, MT

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FXUS65 KTFX 021740
AFDTFX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREAT FALLS MT
1140 AM MDT SUN AUG 2 2015

UPDATED AVIATION SECTION

.DISCUSSION...
NO CHANGES MADE TO THE CURRENT FORECAST PACKAGE. HIGH PRESSURE ALOFT
CONTINUES TO PROVIDE DRY AND STABLE CONDITIONS. THOUGH MINIMUM
RELATIVE HUMIDITIES WILL AGAIN LIKELY DROP BELOW 20 PERCENT, SURFACE
WINDS ARE MUCH LIGHTER THAN WHAT OCCURRED ON SATURDAY. TEMPERATURES
LOOK GOOD.

&&

.AVIATION...
UPDATED 1740Z.
HIGH PRESSURE ALOFT WILL CONTINUE TO PROVIDE DRY AND
STABLE CONDITIONS. SURFACE WINDS WILL GENERALLY BE 10 TO 12 KTS OR
LESS. VFR CONDITIONS PREVAIL.

&&

.PREV DISCUSSION...ISSUED 327 AM MDT SUN AUG 2 2015

TODAY THROUGH TUESDAY...HOT AND DRY CONDITIONS PERSIST TODAY OVER
SOUTHWEST MT WITH A BROAD UPPER LEVEL RIDGE OVER THE INTERIOR
PACIFIC NORTHWEST. TEMPERATURES TREND A FEW DEGREES COOLER BUT
REMAIN ABOVE AVERAGE OVER NORTH-CENTRAL MT AFTER A WEAK COOL FRONT
DISSOLVED INTO THE AREA SATURDAY NIGHT. WV IMAGERY SHOWS
INCREASING MONSOONAL MOISTURE OVER THE GREAT BASIN THAT COULD
YIELD PASSING HIGH CLOUDS. AFTERNOON RELATIVE HUMIDITY WILL ONCE
AGAIN DROP INTO THE 5 TO 15 PERCENT RANGE FOR ALL BUT THE
NORTHEAST ZONES, BUT LIGHT WINDS MITIGATE THE NEED FOR FIRE
WEATHER HEADLINES. EASTERLY WINDS OF 10-20 MPH ARE EXPECTED TO THE
NORTH AND EAST OF THE SURFACE BOUNDARY...BUT RELATIVE HUMIDITY IN
THESE AREAS SHOULD REMAIN NEAR TO ABOVE 20 PERCENT. A MINOR
SHORTWAVE TROUGH WILL DRAW MONSOON MOISTURE THROUGH SOUTHERN
IDAHO AND ACROSS SOUTHWEST MONTANA LATE MONDAY AFTERNOON. THIS
WILL GENERATE SCATTERED THUNDERSTORMS OVER SOUTHWEST MONTANA.
HUMIDITY WILL INCREASE WITH THIS WAVE, BUT THUNDERSTORM ACTIVITY
WILL NOT PRODUCE MUCH PRECIPITATION AND WILL NEED TO BE MONITORED
FOR FIRE WEATHER CONCERNS. THE UPPER LEVEL RIDGE AXIS SHIFTS EAST
OF THE FORECAST AREA MONDAY NIGHT AS A SECONDARY SHORTWAVE TROUGH
MAINTAINS SHOWERS AND THUNDERSTORMS WITH INCREASING AVAILABILITY
OF MOISTURE. GREATEST CHANGE IN THE INHERITED FORECAST WAS TO
RAISE POPS AND LOWER TEMPERATURES ON TUESDAY. PN

TUESDAY NIGHT THROUGH SUNDAY...THE EXTENDED PERIOD WILL BE
CHARACTERIZED BY AN UNSETTLED ZONAL FLOW. TEMPERATURES WILL REMAIN
NEAR TO JUST BELOW AVERAGE. A SHORTWAVE FEATURE WILL GENERATE
SHOWERS OVER THE SOUTHWEST ON WEDNESDAY. MODELS SUGGEST THE REST
OF THE PERIOD WILL BE MAINLY DRY...BUT WILL CONTINUE TO CARRY
SLIGHT CHANCES FOR PRECIP GIVEN LOWER MODEL CONFIDENCE AMID THE
DISTURBED AND MOIST FLOW. PN

&&

.PRELIMINARY POINT TEMPS/POPS...
GTF  91  57  93  63 /   0   0  10  20
CTB  90  54  93  60 /   0   0  10  20
HLN  97  56  96  61 /   0   0  20  20
BZN  93  53  90  56 /   0   0  20  30
WEY  87  43  79  44 /   0   0  20  40
DLN  92  53  86  55 /   0   0  20  30
HVR  89  57  91  59 /   0   0   0  20
LWT  88  56  90  58 /   0   0   0  20

&&

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

$$

WEATHER.GOV/GREATFALLS


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