Area Forecast Discussion
Issued by NWS Billings, MT

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000
FXUS65 KBYZ 042130
AFDBYZ

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BILLINGS MT
330 PM MDT SAT JUL 4 2015

.SHORT TERM...VALID FOR SUN AND MON...

HOT AND UNSTABLE AIRMASS THIS EVENING BUT QUITE DRY INITIALLY SO
BEST CHANCE FOR A EVENING THUNDERSTORM IS OVER THE MOUNTAINS AND
OVER SOUTHEAST MONTANA WHERE MOISTURE IS SLIGHTLY DEEPER. ANY
THUNDERSTORM THAT DOES DEVELOP WILL BE HIGH BASED AND HAVE A
THREAT TO PRODUCE GUSTY WINDS. COLD FRONT WILL PUSH INTO THE AREA
FROM THE NORTH AND BRING A SHIFT TO NORTHEAST. TIMING OF THIS
FRONT IS AROUND 10 PM FOR THE NORTHERN HALF OF THE DISTRICT...11
PM FOR A HARLOWTON TO BILLINGS TO ASHLAND LINE AND THEN MIDNIGHT
FOR LIVINGSTON TO SHERIDAN. THIS WILL BRING MUCH COOLER AIR WITH
HIGHER HUMIDITY SETTING THE STAGE FOR AREAS OF SHOWERS DEVELOPING
ON SUNDAY. TEMPERATURES WILL BE NEARLY 30 DEGREES COOLER ON SUNDAY
WITH THE BEST CHANCE FOR MOISTURE OVER SOUTHERN PORTIONS OF THE
DISTRICT ESPECIALLY IN SOUTHEAST MONTANA.

THE STRONG UPPER LEVEL LOW PRESSURE SYSTEM OVER NORTHEAST ALBERTA
DRIVING THIS DRAMATIC CHANGE IS GOING TO MOVE DUE EAST OVER THE
NEXT 24 HOURS. LOBE OF ENERGY ROTATING SOUTHWARD AROUND THIS
DEPARTING LOW WILL PHASE WITH A PERIOD OF LOW LEVEL UPSLOPE OVER
SOUTHEAST MONTANA AND NORTHERN WYOMING WHICH WILL HELP DEEPEN
MOISTURE AND PROVIDE SUPPORT FOR THE SHOWER ACTIVITY. THIS WAVE
BEGINS TO DEPART THE AREA LATE SUNDAY NIGHT AND THIS ALLOWS DRYING
TO BEGIN. PRECIPITATION AMOUNTS FROM THIS SYSTEM SHOULD MAX OUT
AROUND A QUARTER INCH OF PRECIPITATION SINCE MULTIPLE HOURS OF
SHOWER ACTIVITY SHOULD BE EXPECTED BUT INTENSITY WILL BE MOSTLY
LIGHT.

MONDAY WILL SEE CONTINUED COOL WEATHER BUT THE AIRMASS WILL DRY
OUT AS THE WAVE DEPARTS. SURFACE HIGH PRESSURE BEHIND THE WAVE
WILL SETTLE INTO THE REGION WHICH WILL BRING LIGHT WINDS AND LIMIT
MIXING HELPING SLOW DOWN ANY WARMUP. BORSUM
.LONG TERM...VALID FOR TUE...WED...THU...FRI...SAT...

A NORTHWEST FLOW ALOFT IS EXPECTED TO TRANSITION TO A SOUTHWEST
FLOW THROUGH THE WEEK ACROSS OUR REGION. AS A PACIFIC WEATHER
SYSTEM SLIDES SLOWLY ON TO THE WEST COAST IT WILL PHASE WITH A
NORTHERN STREAM OUT OF CANADA TUESDAY. HOWEVER...THE UPPER STREAM
WILL SHIFT OFF THROUGH CANADA AND THAT UPPER LOW ON THE WEST COAST
WILL SINK SOUTH DOWN THE COAST RESULTING IN SOME RIDGING ACROSS
OUR REGION AFTER MIDWEEK. FOR OUR FORECAST AREA THIS WILL MEAN A
WARMING TREND THROUGH THE WEEK WITH A PERSISTENT BUT LOW CHANCE OF
THUNDERSTORM ACTIVITY FOR MOST LOCATIONS. BT

&&

.AVIATION...

VFR CONDITIONS WILL PREVAIL THE REST OF TODAY. A COLD FRONT WILL
MOVE SOUTH ACROSS THE AREA TONIGHT...AND WINDS BEHIND THE FRONT
WILL SHIFT TO THE NORTH AND INCREASE WITH GUSTS UP TO 30 KT. A FEW
SHOWERS AND THUNDERSTORMS WITH LOCAL SUB-VFR CONDITIONS MAY FOLLOW
THE FRONT INTO THE FORECAST AREA SUNDAY MORNING...WITH INCREASING
SHOWERS SUNDAY AFTERNOON. PLEASE SEE TAFS FOR TIMING DETAILS AS
NECESSARY. BT
&&

.PRELIMINARY POINT TEMP/POPS...

    SUN     MON     TUE     WED     THU     FRI     SAT
-----------------------------------------------------------
BIL 064/068 054/076 055/084 059/084 061/092 065/092 063/090
    25/W    21/B    11/B    21/B    11/U    22/T    22/T
LVM 057/068 048/078 049/084 051/083 053/090 056/089 055/087
    25/W    32/T    22/T    22/T    12/T    22/T    22/T
HDN 062/071 054/078 055/086 058/086 059/095 062/094 061/092
    25/W    21/B    11/B    21/B    11/U    22/T    22/T
MLS 064/072 054/076 054/084 058/085 060/093 064/094 065/090
    36/W    21/B    01/B    11/B    11/U    12/T    22/T
4BQ 064/076 055/075 053/083 058/083 059/090 062/093 063/090
    27/T    31/B    11/B    22/T    11/U    22/T    23/T
BHK 062/071 053/072 050/079 055/080 056/087 060/090 061/085
    26/T    31/B    01/B    22/T    11/U    12/T    23/T
SHR 060/070 051/073 051/080 054/080 054/088 057/088 057/087
    27/T    41/B    22/T    32/T    21/B    22/T    22/T

&&

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

&&

$$
WEATHER.GOV/BILLINGS


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