High Wind in Montana, March 10, 2016

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREAT FALLS MT
1032 AM MST THU MAR 10 2016

UPDATED AVIATION SECTION

.DISCUSSION...
NO UPDATE NECESSARY THIS MORNING AS CURRENT FORECAST LOOKS ON TRACK.
STRONG SOUTHWEST FLOW ALOFT WILL KEEP PLAINS DRY DUE TO DOWNSLOPE
EFFECTS. VERY MILD TEMPERATURES STILL ON TRACK FOR THE AFTERNOON.

&&

.AVIATION...
UPDATED 1732Z.
STRONG SOUTHWEST FLOW ALOFT WILL CONTINUE TO BRING MID AND HIGH
LEVEL MOISTURE TO THE AREA. SCATTERED MOUNTAIN SNOW SHOWERS WILL BE
POSSIBLE BUT THE PLAINS WILL REMAIN DRY. GUSTY SOUTHWEST WINDS WILL
CONTINUE ACROSS THE PLAINS, WITH THE STRONGEST WINDS ALONG THE ROCKY
MOUNTAIN FRONT. WINDS SHOULD BEGIN TO DECREASE AFTER 02Z. VFR
CONDITIONS PREVAIL.

&&

.PREV DISCUSSION...ISSUED 338 AM MST THU MAR 10 2016

TODAY THROUGH SATURDAY...A STRONG SOUTHWEST FLOW WILL BRING WARMER
TEMPERATURES AND WINDY CONDITIONS THROUGH CENTRAL AND SOUTHWEST
MONTANA TODAY. A WELL-DEFINED WEATHER SYSTEM MOVED INTO THE PAC-
NW EARLY THIS MORNING AND PUSHED RAIN AND SNOW SHOWERS UP TO THE
CONTINENTAL DIVIDE. MID AND HIGH CLOUDS WILL SPREAD OVER OUR
REGION TODAY, BUT THE STRONG DOWNSLOPE FLOW WILL SUPPRESS ALL BUT
A FEW LIGHT SHOWERS OVER THE WESTERN AND SOUTHWEST MOUNTAINS.
FORECAST SOUNDINGS REVEAL A DRY AND DEEPLY MIXED BOUNDARY LAYER
THIS AFTERNOON ACROSS NORTH-CENTRAL MT, ENABLING STRONG WINDS
ALOFT TO MIX DOWN TO THE SURFACE. THE COMBINATION OF STRONG WINDS
AND LOW AFTERNOON RELATIVE HUMIDITY CREATES ELEVATED FIRE WEATHER
CONCERNS WITH THE POTENTIAL FOR RAPID SPREAD OF ANY GRASSLAND
FIRES. A WEAK FRONT MOVES THROUGH THE STATE TONIGHT INTO FRIDAY.
THE TAIL END OF THIS FRONT STALLS OVER THE SOUTHWEST, PROVIDING A
FOCUS FOR SCATTERED SHOWERS FRIDAY AFTERNOON THAT DRIFT NORTH AND
EAST INTO CENTRAL. THE MOIST PACIFIC SOUTHWEST FLOW CONTINUES ON
SATURDAY, BUT EXPECTING FEWER MOUNTAIN SHOWERS WITH LESS
ORGANIZED UPPER LEVEL FORCING. PN

SATURDAY NIGHT THROUGH THURSDAY...FORECAST CONFIDENCE INCREASING
ON THE SIGNIFICANT CHANGE TO COOLER AND WETTER CONDITIONS FOR
FIRST HALF OF NEXT WEEK. LATEST FORECAST MODELS SHOWING IMPROVED
RUN-TO- RUN CONSISTENCY AND AGREEMENT ON EVOLUTION OF THE PACIFIC
LONGWAVE TROF THAT REACHES THE PACNW COAST THIS WEEKEND. FORECAST
STILL ON TRACK FOR THE FIRST WAVE OF MOISTURE FROM THE LONGWAVE TO
GENERATE VALLEY RAIN/MTN SNOW ALONG/EAST OF THE CONTINENTAL DIVIDE
ON SUN. AFTER A BRIEF BREAK IN THE PRECIPITATION SUN NIGHT, A
STRONG UPPER- LEVEL TROF EMBEDDED IN THE LONGWAVE FLOW, AND
ACCOMPANIED BY A SURFACE COLD FRONT AND PLENTIFUL MOISTURE, WILL
REACH OUR AREA ON MON. THERE ARE SOME SLIGHT TIMING DIFFERENCES ON
THE FRONT/PRECIP'S ARRIVAL, WITH THE GFS MODEL CURRENTLY ABOUT 6
HRS QUICKER (FRONTAL PASSAGE MON MORNING) THAN THE ECMWF SOLUTION
(MON AFTN/EVE), BUT MODEL AGREEMENT IS REASONABLY GOOD ON PRECIP
COVERAGE AND AMOUNTS.

MODELS ARE ALSO IN SYNC ON ARRIVAL OF A MUCH-COOLER CANADIAN AIRMASS
BEHIND THE FRONT (THICKNESS VALUES DROPPING INTO THE 5250-5300 METER
RANGE BY TUES MORNING), WITH THE COLD AIR BEING REINFORCED BY A
SECOND PUSH OF COLDER AIR TUES AFTN THROUGH TUES NIGHT. THIS WILL
RESULT IN PRECIPITATION STARTING AS VALLEY RAIN/MTN SNOW ON MON AND
TRANSITION TO ALL LIGHT SNOW BY LATE MON NIGHT/EARLY TUES AS SNOW
LEVELS DROP TO VALLEY/PLAINS ELEVATIONS. STILL A BIT EARLY TO
PREDICT SNOWFALL AMOUNTS, BUT MODEL TOTAL PRECIP VALUES ARE
GENERALLY IN THE 0.1 TO 0.25 INCH RANGE FROM MON THROUGH THURS AFTN,
WHICH SUGGESTS LIGHT SNOW AMOUNTS. NOT EXPECTING MUCH IMPACT FROM
THE SNOW, AS OUR EXTENDED RUN OF ABOVE NORMAL TEMPERATURES HAS
WARMED GROUND TEMPS AS WELL, WHICH SHOULD INITIALLY MELT MUCH OF THE
SNOW AS IT FALLS.  THE SNOW WILL TAPER OFF ON THURS AS THE LONGWAVE
ENERGY AND MOISTURE HEAD INTO THE CENTRAL ROCKIES AND UPPER MIDWEST
STATES. THE SAME CANADIAN AIRMASS WILL ALSO BRING AN END TO OUR
UNSEASONABLY WARM CONDITIONS, AS HIGH TEMPS RETURN TO THE UPPER 30S
TO LOW 40S ON TUES/WED AND LOW-MID 40S ON THURS.
WARANAUSKAS

&&

.PRELIMINARY POINT TEMPS/POPS...
GTF  64  38  58  39 /   0  20  10  20
CTB  57  33  56  34 /   0  10   0  20
HLN  62  36  54  36 /   0  20  30  30
BZN  61  37  58  35 /  10  30  30  10
WEY  44  30  46  29 /  40  30  30  20
DLN  58  36  55  35 /  10  30  40  20
HVR  69  38  60  37 /   0  10   0  10
LWT  63  36  54  37 /   0  10  40  20

&&

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

WEATHER.GOV/GREATFALLS