Area Forecast Discussion
Issued by NWS Great Falls, MT

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FXUS65 KTFX 271150
AFDTFX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREAT FALLS MT
550 AM MDT MON JUL 27 2015

UPDATED AVIATION SECTION

.DISCUSSION...
MONDAY THROUGH WEDNESDAY...AN UPPER LEVEL LOW WILL CONTINUE TO
MOVE THROUGH THE REGION BRINGING COOL TEMPERATURES AND
UNSEASONABLY WET CONDITIONS FOR THE NEXT FEW DAYS. RAINFALL
AMOUNTS ARE GENERALLY EXPECTED TO BE IN THE QUARTER INCH TO ONE
INCH RANGE...HOWEVER SOME LOCATIONS MAINLY IN HILL AND BLAINE
COUNTY COULD RECEIVE AMOUNTS OVER 2 INCHES. THERE IS A SLIGHT
CONCERN FOR FLOODING OF AREAS THAT RECEIVE CONSTANT PRECIPITATION
OVER THIS TIME FRAME THAT COULD OVERWHELM SMALL STREAMS AND FLOOD
PRONE SLOPES...BUT WIDESPREAD FLOODING IS NOT ANTICIPATED. BY
TUESDAY AFTERNOON THE SYSTEM WILL BEGIN TO EXIT THE AREA TO THE
EAST AND TEMPERATURES SHOULD QUICKLY REBOUND BACK TOWARD SEASONAL
VALUES. BY WEDNESDAY TEMPERATURES WILL BE NEAR SEASONAL AVERAGES
AND CONDITIONS WILL BEGIN TO DRY OUT. SUK

WEDNESDAY NIGHT THROUGH MONDAY...MEDIUM RANGE PERIOD LOOKS GENERALLY
QUIET AND DRY WITH ZONAL FLOW ALOFT OVER THE AREA. MONSOONAL
MOISTURE MAKES ITS WAY OVER SOUTHWEST MONTANA BEGINNING SATURDAY
ALLOWING FOR THE POSSIBILITY OF ISOLATED MOUNTAIN THUNDERSTORMS.
MONSOONAL MOISTURE CONTINUES TO INVADE SOUTHWEST MONTANA SUNDAY WITH
SCATTERED THUNDERSTORMS DEVELOPING DURING THE AFTERNOON AND EVENING
HOURS. AT THE SAME TIME, WEAK SHORT WAVE ENERGY MOVES ALONG THE
INTERNATIONAL BOUNDARY PRODUCING ISOLATED CONVECTIVE ACTIVITY ALONG
THE HI-LINE. MODEL SOLUTIONS DIVERGE SIGNIFICANTLY MONDAY WITH THE
GFS MAINTAINING WESTERLY FLOW ALOFT AND WEAK IMPULSES ACROSS
SOUTHERN CANADA. THE EUROPEAN DEVELOPS AN UPPER RIDGE OVER WESTERN
MONTANA. HAVE GONE WITH A GENERALLY DRY SOLUTION MONDAY, THE
EXCEPTION BEING SOUTHWEST MONTANA WHERE ISOLATED THUNDERSTORMS ARE
STILL POSSIBLE. TEMPERATURES WILL BE NEAR TO SLIGHTLY ABOVE SEASONAL
AVERAGES THROUGH THE PERIOD.

&&

.AVIATION...
UPDATED 1150Z.
MOIST AND UNSTABLE SOUTHWEST FLOW ALOFT WILL
CONTINUE. WIDESPREAD SHOWERS AND ISOLATED THUNDERSTORMS WILL
CONTINUE BEYOND 00Z BUT DIMINISH BY 06Z. MVFR CONDITIONS PREVAIL DUE
TO LOW CEILINGS AND PRECIPITATION. MOUNTAINS OBSCURED.

&&

.HYDROLOGY...
SHOWERS AND THUNDERSTORMS WILL CONTINUE TO MOVE ACROSS THE AREA
MONDAY AS A LOW PRESSURE TROUGH MOVES INTO THE REGION AND BECOMES
A CLOSED LOW WITH A SECOND PUSH OF RAIN FROM THE NORTH MONDAY
EVENING. THIS SETUP IS SIMILAR TO A LATE WINTER EARLY SPRING
SYSTEM WHERE SOME FLOOD PRONE LOCATIONS...LIKE THE NORTH SLOPES OF
THE BEARS PAW MOUNTAINS... HIGHWOODS... AND LITTLE BELTS MAY
EXPERIENCED PROLONGED PERIODS OF ENHANCED PRECIPITATION. THIS HAS
THE POTENTIAL TO CREATE SOME AREAS OF FLOODING IN PRONE LOCATIONS.
BECAUSE CONDITIONS AHEAD OF THE SYSTEM HAVE BEEN DRY THERE IS A
HIGH CONFIDENCE THAT THE SOILS WILL BE ABLE TO ABSORB A
SIGNIFICANT AMOUNT OF MOISTURE...HOWEVER IF RAINFALL RATES
OVERWHELM SOIL ABSORPTION RATES SOME MINOR FLOODING COULD OCCUR
ESPECIALLY IN LOCATIONS LIKE SMALL STREAMS AND FIRE BURN SCARS.

&&

.PRELIMINARY POINT TEMPS/POPS...
GTF  54  49  71  51 /  90  70  30  10
CTB  58  50  72  50 /  80  80  20  10
HLN  55  46  72  49 /  90  60  20  10
BZN  58  46  72  48 /  80  60  20  10
WEY  60  32  64  33 /  40  40  20   0
DLN  56  38  69  44 /  90  60  20   0
HVR  61  53  73  52 / 100 100  60  10
LWT  61  48  70  50 /  80  50  50  10

&&

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

$$

WEATHER.GOV/GREATFALLS



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