951 
FXUS65 KTFX 271753
AFDTFX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREAT FALLS MT
1145 AM MDT SAT OCT 27 2012

AVIATION SECTION UPDATED

.UPDATE...
INCREASED POPS THIS MORNING AS SNOW CONTINUES TO FALL ACROSS PARTS
OF NORTH-CENTRAL MONTANA. SNOW WILL CONTINUE THROUGH AT LEAST NOON
TODAY BEFORE TAPERING WITH ADDITIONAL SNOW ACCUMULATIONS OF 1 TO 2
INCHES BELOW 6000 FEET AND 2 TO 4 INCHES ABOVE 6000 FEET.
VISIBILITIES MAY BE REDUCED TO LESS THAN ONE HALF OF A MILE AT
TIMES AND ROADWAYS MAY BECOME SNOW-COVERED AND SLIPPERY.
CONDITIONS WILL IMPROVE THIS AFTERNOON. MLV

&&

.AVIATION...
UPDATED 1745Z.
FIRST OF TWO UPPER LEVEL TROFS EXPECTED TO CROSS MT OVER NEXT 24 HRS 
IS TRACKING THRU CENTRAL MT AT THIS TIME...WITH THE SECOND SYSTEM 
DUE TO ARRIVE SUN MORNING.  WIDESPREAD VFR/MVFR CEILINGS AND AREAS 
OF LIGHT SNOW WILL CONTINUE THROUGH THIS AFTN.  VISIBILITIES AND 
CEILINGS WILL OCCASIONALLY DROP TO IFR CATEGORY DUE TO FOG 
ACCOMPANYING THE SNOW.  SNOW IS EXPECTED TO TAPER OFF FOR A TIME 
THIS EVE AS FIRST SYSTEM MOVES INTO ERN MT.  SNOW AND WIDESPREAD 
MVFR TO IFR CEILINGS REDEVELOP 09-12Z TOMORROW AS SECOND TROF 
CROSSES THE ROCKY MTN FRONT.  FORECAST MODELS CONTINUE TO SHOW 
TOMORROW'S SYSTEM TRACKING FAIRLY QUICKLY ACROSS CENTRAL/SOUTHWEST 
MT WITH SKIES GRADUALLY CLEARING FROM WEST TO EAST BY MID-LATE AFTN.
WARANAUSKAS

&&

.PREV DISCUSSION...
/ISSUED 530 AM MDT SAT OCT 27 2012/

TODAY THROUGH MONDAY...UNSTABLE NORTHWEST FLOW ALOFT CONTINUES
SHORT WAVE ENERGY MOVING ACROSS THE AREA THIS MORNING IS PRODUCING
LIGHT SNOW ACROSS PORTIONS OF NORTH CENTRAL MONTANA. SNOW
ACCUMULATIONS OVER THE PLAINS ARE GENERALLY LIGHT WITH THIS
FEATURE. HEAVIER AMOUNTS ARE POSSIBLE IN THE MOUNTAINS AND A
WINTER WEATHER ADVISORY REMAINS IN EFFECT FOR ELEVATIONS ABOVE
6000 FEET OVER SOUTHWEST AND PORTIONS OF NORTH CENTRAL MONTANA.
SNOW WILL TAPER OFF THIS AFTERNOON. 500 MB HEIGHTS BEGIN TO RISE
TONIGHT BUT ADDITIONAL SHORT WAVE ENERGY WILL PUSH ACROSS THE AREA
RESULTING IN ANOTHER ROUND OF LIGHT SNOW OVERNIGHT AND INTO EARLY 
SUNDAY. WITH THE BUILDING RIDGE TONIGHT...WARM AIR ADVECTION 
OVERNIGHT WILL LIFT OVER THE COLD AIRMASS ALREADY IN PLACE AND MAY 
CAUSE AREAS OF FREEZING RAIN. WITH ABUNDANT LOW LEVEL MOISTURE 
REMAINING IN PLACE OVER THE AREA AND TRANSIENT SHORT WAVE ENERGY 
MOVING THROUGH THE FLOW ALOFT...SCATTERED RAIN AND SNOW SHOWERS WILL 
CONTINUE ON MONDAY. A TIGHTENING SURFACE GRADIENT SUNDAY WILL ALLOW 
FOR GUSTY WINDS...MAINLY ALONG THE EAST SLOPES OF THE ROCKIES. AT 
THIS POINT IN TIME...WIND SPEEDS SHOULD REMAIN BELOW WARNING 
CRITERIA. TEMPERATURES SHOULD REMAIN BELOW SEASONAL AVERAGES TODAY 
BUT WARM TO SEASONAL AVERAGES TO START THE WEEK. EMANUEL 

MONDAY NIGHT THROUGH SATURDAY...MODELS CONTINUE TO KEEP A WEAK UPPER 
LEVEL RIDGE OVER THE REGION FOR THE BULK OF THE LONG TERM PERIOD. IT 
SHOULD BE NOTED THAT ALTHOUGH THE RIDGE IS THE LARGE SCALE SYNOPTIC 
FEATURE SOME SHORTWAVE TROUGHS WILL MOVE THROUGH DURING THE TIME 
FRAME AND WILL BRING SOME MOISTURE AND INSTABILITY TO THE REGION. 
THE BEST EXAMPLE OF THE SHORTWAVES WILL OCCUR AS THE LONG TERM 
PERIOD BEGINS. MOISTURE WILL CONTINUE TO BE ADVECTED FROM THE 
PACIFIC AND WHILE THE BULK OF THE PRECIPITATION WILL FALL WEST OF 
THE DIVIDE SOME MOUNTAIN SHOWERS ARE POSSIBLE WITH A LESSER CHANCE 
OF PRECIPITATION OCCURRING OVER THE LOWER ELEVATIONS. TEMPERATURES 
WARM PAST SEASONAL AVERAGES BY TUESDAY AFTERNOON AND SOME LOCATIONS 
COULD SEE NEARLY 10 DEGREES ABOVE SEASONAL NORMALS THROUGH THURSDAY. 
BY FRIDAY A LOW PRESSURE TROUGH DOES SWING THROUGH THE AREA AND 
BRING THE NEXT SOLID CHANCE OF WIDESPREAD PRECIPITATION. THIS LOW IS 
CURRENTLY BEING FORECASTED BY THE MAJOR MODEL SUITES TO BE A PACIFIC 
SYSTEM WHICH WILL BRING THE POTENTIAL FOR PLENTY OF MOISTURE...AND A 
RELATIVELY MILD DROP IN TEMPERATURES FRIDAY THROUGH SATURDAY...WHERE 
CURRENT TEMPERATURES ARE EXPECTED TO DROP BACK DOWN TO SEASONAL 
AVERAGES. AFTER THIS SYSTEM EXITS...THE MODELS QUICKLY DIVERGE AND 
AND REMOVE ANY CONFIDENCE IN THE MODEL SOLUTIONS BY 228 HOURS OUT. 
SUK  

&&

.PRELIMINARY POINT TEMPS/POPS...
GTF  37  31  54  38 /  90  30  30  30 
CTB  33  25  49  30 /  80  40  20  40 
HLN  39  31  53  37 /  80  40  30  50 
BZN  41  29  55  36 /  50  40  30  50 
WEY  34  21  43  27 /  90  50  60  50 
DLN  42  30  55  36 /  20  30  30  30 
HVR  34  22  49  28 /  20  20  20  20 
LWT  35  26  51  35 /  50  20  30  40 

&&

.TFX WATCHES/WARNINGS/ADVISORIES...
WINTER WEATHER ADVISORY UNTIL NOON MDT TODAY FOR ELEVATIONS 
ABOVE 6000 FEET FOR BEAVERHEAD...BROADWATER...CASCADE...CENTRAL 
AND SOUTHERN LEWIS AND CLARK...GALLATIN...JEFFERSON...JUDITH 
BASIN...MADISON...MEAGHER.

&&

$$

WEATHER.GOV/GREATFALLS