Area Forecast Discussion
Issued by NWS Billings, MT

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FXUS65 KBYZ 171459
AFDBYZ

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE BILLINGS MT
859 AM MDT SUN MAY 17 2015

.UPDATE...
EARLY UPDATE THIS MORNING TO RAISE OUR POPS TO DEFINITE TERMS
WHERE RADAR IS OBVIOUSLY SOCKED IN...MAINLY OVER WESTERN AND
CENTRAL ZONES THIS MORNING. LOWERED POPS OUT EAST FOR MORNING AS
NOTHING OCCURRING OUT THERE NOW...THOUGH WE SHOULD SEE SOME OF
THE ACTIVITY SPREAD TO THE EAST AS THE DAY GOES ON. BT

&&

.SHORT TERM...VALID FOR TDY AND MON...

NEARLY STATIONARY UPPER LOW CONTINUES TO SPIN OVER EASTERN MT.
MORE DYNAMIC LOW OVER THE CENTRAL PLAINS WILL LIFT TO THE RED
RIVER VALLEY TODAY...AS LOW OVER OUR REGION GRADUALLY WEAKENS AND
PULLS EAST. NOT MUCH SYNOPTIC FORCING FOR US TODAY...BUT THE
COMBINATION OF ABUNDANT MOISTURE WRAPPED INTO THIS SYSTEM AND
CYCLONIC FLOW ALOFT WILL KEEP SHOWER ACTIVITY GOING THROUGH THE
DAY. THERE WILL BE SOME SHALLOW INSTABILITY BUT NOT WHAT WE SAW
YESTERDAY PER MUCH COOLER SFC TEMPS...SO NO RISK OF TSTMS TODAY.
WILL KEEP LIKELY TO CATEGORICAL POPS BROADBRUSHED ACROSS THE CWA
TODAY FOR WHAT WILL BE VERY UNORGANIZED AND GENERALLY LIGHTER
SHOWER ACTIVITY. GREATEST PCPN AMOUNTS WILL BE OVER THE SOUTHERN
UPSLOPE AREAS. OUR MOUNTAINS WILL SEE A LITTLE MORE SNOW
ACCUMULATION BUT AMOUNTS WILL BE LIMITED ESPECIALLY DURING THE
DAYTIME HOURS...SO HAVE OPTED TO CANCEL THE WINTER STORM WARNING
FOR THE BEARTOOTH ABSAROKAS.

CLIPPER IN NORTHERN ONTARIO IS ALLOWING FOR A SURGE OF COLDER
CANADIAN AIR TO GET WRAPPED INTO THE CURRENT SYSTEM. IT HAS BEEN
SNOWING OCCASIONALLY IN CALGARY AND WE ARE EXPECTING 850MB TEMPS
TO FALL BELOW ZERO LATER TODAY AND TONIGHT AS WE COLD ADVECT FROM
THE NORTH WITH BUILDING SFC RIDGE. STILL EXPECTING A MIX WITH WET
SNOW BY TONIGHT...ESPECIALLY IN OUR EAST BUT THIS MAY ALSO INCLUDE
THE BILLINGS AREA AS SFC WINDS SHIFT TO THE EAST. NOT EXPECTING
ANY ACCUMULATION FOR THE LOWER ELEVATIONS BUT IT WOULD BE
INTERESTING AS ARE NOW IN THE LATTER HALF OF MAY. THE COLD
ADVECTION TODAY WILL KEEP TEMPS VERY CHILLY WITH HIGHS IN THE
UPPER 40S TO LOW 50S...IE NEAR THEIR CURRENT VALUES. COULD SEE A
FROST OR FREEZE TONIGHT BUT CLOUD COVER MAY KEEP TEMPS FROM
FALLING TOO FAR. RECORD LOWS AT BILLINGS AND MILES CITY WILL BE
CHALLENGED NONETHELESS.

WE WILL BE DOMINATED BY CANADIAN SFC RIDGE IN THE NORTHERN PLAINS
ON MONDAY...IE CHILLY TEMPS AND PERSISTENT EAST WINDS. HIGHS
SHOULD CLIMB INTO THE 50S BUT THIS IS STILL WELL BELOW NORMAL...
AND THERE WILL BE A RISK OF ANOTHER FROST OR FREEZE MONDAY NIGHT
ESPECIALLY FOR OUR EAST. ONLY CHANCE OF SHOWERS ON MONDAY WILL BE
OVER OUR WESTERN MOUNTAINS AND FOOTHILLS.

JKL

.LONG TERM...VALID FOR TUE...WED...THU...FRI...SAT...

TUESDAY AN UPPER LOW WILL SWING FROM UTAH INTO WYOMING WHILE A
RIDGE WILL BE IN PLACE OVER ALBERTA AND SASKATCHEWAN. SURFACE
HIGH PRESSURE OVER THE DAKOTAS WILL KEEP A DRY LOW LEVEL EASTERLY
IN PLACE FOR MOST OF THE AREA WHILE SOME MOISTURE IS ADVECTED INTO
EASTERN WYOMING. MODELS CONTINUE TO SHOW THIS AS A GLANCING BLOW
WITH THE BEST CHANCE OF PRECIPITATION OVER SOUTHERN PORTIONS OF
SOUTHEAST MONTANA PUSHING A BIT FURTHER NORTHWARD TUESDAY NIGHT.
THERE ALSO MAY BE SOME DIURNAL SHOWER ACTIVITY ALONG THE FOOTHILLS
AND MOUNTAINS DUE TO THE UPSLOPE FLOW AND RECENT MOISTURE BUT
INTENSITY WILL BE LIMITED GIVEN THE COOL TEMPERATURES FOR THIS
TIME OF YEAR.

SYSTEM FILLS ON WEDNESDAY AND FLOW ALOFT AND AT THE SURFACE
BECOMES WEAK SO OROGRAPHIC SHOWERS ARE POSSIBLE BUT NO FORCING
MECHANISMS AROUND. STILL LIGHT EASTERLY FLOW SO TEMPERATURES WILL
REMAIN COOL. THIS PATTERN CHANGES LITTLE ON THURSDAY.

FRIDAY ANOTHER LOW MOVES INTO THE GREAT BASIN AND GENERATES SOME
CYCLOGENESIS EAST OF THE COLORADO ROCKIES. THIS OPENS THE DOOR FOR
A BIT BETTER MOISTURE TRANSPORT UP THE HIGH PLAINS BUT STILL LOOKS
LIKE A PATTERN WHERE ANY SHOWERS WILL BE FAIRLY DISORGANIZED
ESPECIALLY WITH THE BOUNDARY LAYER REMAINING COOL. SATURDAY SEES
A A BETTER CHANCE FOR A WESTERLY SURFACE FLOW TO DEVELOP AS THE
SOUTHERN LOW CONTINUES TO MOVE EAST AND SUNSHINE COULD HELP PUSH
TEMPERATURES INTO THE UPPER 60S AND POSSIBLY A FEW 70S BY SUNDAY.
BORSUM
&&

.AVIATION...

MOIST AIRMASS ACROSS THE REGION WILL CONTINUE TO BRING LOW
CEILINGS BUT PRECIPITATION INTENSITY AND COVERAGE WILL BE LESS
THAN OTHER DAYS. EXPECT WIDESPREAD MVFR TO IFR CEILINGS WITH
FOOTHILL AND MOUNTAIN OBSCURATIONS. BORSUM
&&

.PRELIMINARY POINT TEMP/POPS...

    TDY MON     TUE     WED     THU     FRI     SAT
-------------------------------------------------------
BIL 048 035/053 038/057 040/054 040/062 043/064 045/066
    +/R 41/B    01/E    43/W    22/W    22/W    23/W
LVM 051 033/052 034/055 038/054 037/061 039/063 041/065
    8/R 32/W    22/W    43/W    33/W    23/W    33/W
HDN 048 034/057 037/059 039/057 039/065 043/067 044/069
    9/R 41/B    01/E    33/W    11/B    23/W    33/W
MLS 047 032/054 034/059 037/058 039/062 043/064 045/067
    7/W 40/B    01/B    32/W    11/B    12/W    22/W
4BQ 049 032/054 034/055 036/054 038/060 043/062 046/066
    6/W 40/B    02/W    53/W    11/B    13/W    33/W
BHK 048 028/052 028/056 034/055 036/059 040/061 043/062
    5/W 40/B    00/B    32/W    11/B    11/B    22/W
SHR 048 032/055 036/054 035/054 035/060 041/062 042/064
    6/W 41/B    13/W    54/W    22/W    23/W    44/W

&&

.BYZ WATCHES/WARNINGS/ADVISORIES...
MT...NONE.
WY...NONE.

&&

$$
WEATHER.GOV/BILLINGS


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