Area Forecast Discussion
Issued by NWS Billings, MT

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000
FXUS65 KBYZ 180924
AFDBYZ

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BILLINGS MT
324 AM MDT MON MAY 18 2015

.SHORT TERM...VALID FOR TDY AND TUE...

UPPER LOW RESPONSIBLE FOR OUR WEEKEND WEATHER IS NOW IN NORTHERN
MN. OUR REGION IS UNDERGOING WEAK RIDGING WITH ANOTHER LOW MOVING
FROM CA TO THE GREAT BASIN. COOL CANADIAN SFC RIDGE IS BUILDING
INTO THE NORTHERN PLAINS. LOW LEVEL MOISTURE WILL SCOUR OUT OF OUR
NORTHEAST PARTS SOON BUT IT APPEARS MOISTURE WILL REMAIN IN PLACE
ACROSS OUR WEST PER THE EASTERLY FLOW...THUS TEMPS NOT FALLING AS
LOW AS THEY COULD HAVE IN OUR WEST. SHOULD SEE A FREEZE IN OUR
EAST EARLY THIS MORNING AND FEEL THAT MILES CITY RECORD LOW OF 34F
ON THE 18TH WILL BE BROKEN OVER THE NEXT FEW HOURS.

COULD BE SOME LIGHT UPSLOPE SPRINKLES/FLURRIES IN OUR WEST EARLY
THIS MORNING...OTHERWISE A DRY AND COOL DAY WITH EAST WINDS AS WE
REMAIN DOMINATED BY NORTHERN PLAINS SFC RIDGE. MAY SEE SOME WEAK
LATE AFTERNOON AND EVENING CONVECTION OVER OUR SOUTHERN MTNS AS
GREAT BASIN MOISTURE CREEPS NORTHWARD.

WEAK GREAT BASIN LOW WILL LIFT INTO WY TUESDAY THEN INTO SD/NE
TUESDAY NIGHT. MODELS CONTINUE TO TREND SOUTHWARD WITH ITS TRACK
AND HEAVIEST PCPN WILL STAY ALONG BAROCLINIC ZONE TO OUR S/SE...
WITH SOME LIGHTER PCPN EKING ITS WAY INTO OUR SOUTHERN TIER
TUESDAY AFTERNOON AND NIGHT. SHOULD SEE A LITTLE SNOW ACCUMULATION
OVER THE BIGHORNS...AND A MIX WITH SNOW IS POSSIBLE OVER SOUTHERN
CARTER COUNTY AND PERHAPS SHERIDAN TUESDAY NIGHT WITH 850MB TEMPS
DYNAMICALLY COOLED TO NEAR OR A BIT BELOW 0C. OVERALL PCPN SHOULD
STAY LESS THAN A QUARTER INCH ACROSS OUR SOUTH. HAVE LOWERED POPS
ACROSS OUR NORTH. FOR BILLINGS...THOUGH IT WILL BE CLOUDY TUESDAY
AND TUESDAY NIGHT...IT LOOKS AS IF WE WILL KEEP A DRY SUB-CLOUD
LAYER WHICH WOULD LIMIT OUR PCPN TO SPRINKLES OR VERY LIGHT
SHOWERS...WITH THE COOL EASTERLY SFC FLOW NOT ALLOWING FOR ANY
INSTABILITY TO BUILD UP.

TEMPS THE NEXT COUPLE DAYS WILL MAX OUT ONLY IN THE 50S...WITH
MAINLY 30S AT NIGHT. EASTERN LOCATIONS COULD SEE ANOTHER FREEZE
TONIGHT.

JKL

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

MIDLEVEL MOISTURE DECREASES DURING THE DAY ON WEDNESDAY AS THE
UPPER LOW FILLS SOUTHEAST OF THE AREA AND HEIGHTS WEAKLY BUILD
OVER WESTERN WYOMING. EASTERLY SURFACE FLOW WILL CONTINUE TO KEEP
COOL UPSLOPE OVER THE AREA BUT SHOWER ACTIVITY SHOULD BE LIMITED
TO THE HIGHER TERRAIN. AS THE WEAK RIDGE OVER WYOMING SHIFTS EAST
IT ALLOWS A LIGHT SOUTHWEST FLOW ALOFT TO REACH INTO SOUTHWEST
MONTANA INCREASING THE MID LEVEL MOISTURE ON THURSDAY. EXPECT A
BIT BETTER SHOWER COVERAGE ON THURSDAY INTO THE FOOTHILLS BUT
STILL NOT ENOUGH INSTABILITY TO MOVE MOST OF THIS ACTIVITY INTO
THE PLAINS.

FRIDAY AND SATURDAY THE OVERALL PATTERN IS FOR A VERY WEAK AND
BROAD TROUGH AXIS TO PASS THROUGH THE REGION WITH SURFACE FLOW
REMAINING EASTERLY. THE UPSLOPE COMPONENT OF THE LOW LEVELS WILL
KEEP TEMPERATURES BELOW NORMAL BUT MAY HELP MOISTURE POOL ENOUGH
FOR A BIT MORE SHOWER ACTIVITY ESPECIALLY WITH SLIGHTLY COOLER AIR
ALOFT PRESENT. MOISTURE TRANSPORT ON SATURDAY MAY BE STRONGER OVER
SOUTHEAST MONTANA AS THE SYSTEM BEGINS TO EMERGE ON THE HIGH
PLAINS BUT MODELS SEEM TO FAVOR THE BLACK HILLS MUCH MORE THAN
SOUTHEAST MONTANA.

FOR SUNDAY AND MONDAY MODELS ARE HAVING TROUBLE RESOLVING THE
MOTION OF AN UPPER LOW OVER THE PACIFIC NORTHWEST. IN GENERAL THE
PATTERN LOOKS A LITTLE LESS TROUGHY AND CONTINUED UNSETTLED BUT A
BIT MORE STABILITY WILL BE PRESENT ESPECIALLY OVER THE EASTERN
HALF OF THE AREA. BELOW NORMAL TEMPERATURES WILL DOMINATE THE
PERIOD. BORSUM
&&

.AVIATION...

LOW LEVEL MOISTURE AND EASTERLY FLOW WILL KEEP MVFR CONDITIONS
OVER MOST OF THE AREA UNTIL THE MID MORNING HOURS. CLOUDS WILL
BEGIN LIFTING TOWARDS MIDDAY WITH VFR CEILINGS FOR MOST OF THE
AREA BY AFTERNOON. BORSUM
&&

.PRELIMINARY POINT TEMP/POPS...

    TDY TUE     WED     THU     FRI     SAT     SUN
-------------------------------------------------------
BIL 054 038/056 038/057 039/064 043/065 045/066 046/065
    0/B 01/E    12/W    11/B    12/W    23/W    34/W
LVM 051 034/053 037/055 036/062 039/065 041/065 042/064
    1/M 12/W    23/W    33/W    33/W    33/W    34/W
HDN 058 037/057 037/061 038/067 043/068 045/068 045/068
    0/B 01/E    22/W    11/B    12/W    23/W    33/W
MLS 055 034/059 036/060 038/065 044/066 045/066 046/067
    0/U 00/B    12/W    11/B    12/W    22/W    23/W
4BQ 054 035/052 035/057 036/062 043/064 044/064 044/064
    0/B 03/W    43/W    11/B    12/W    23/W    33/W
BHK 052 027/056 033/059 034/062 041/063 043/062 043/064
    0/U 00/U    12/W    10/B    02/W    22/W    23/W
SHR 055 036/050 033/055 035/061 040/064 041/064 043/062
    0/B 05/W    53/W    12/W    23/W    44/W    45/W

&&

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

&&

$$
WEATHER.GOV/BILLINGS


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