Area Forecast Discussion
Issued by NWS Billings, MT

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FXUS65 KBYZ 022052
AFDBYZ

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BILLINGS MT
252 PM MDT MON MAY 2 2016

.SHORT TERM...VALID FOR TUE...WED...THU...

A VERY QUIET SHORT TERM FORECAST FOR THIS TIME OF YEAR. STRONG
OMEGA BLOCK PATTERN IN PLACE WILL KEEP SUNNY...DRY...AND WARM
CONDITIONS IN PLACE. TEMPERATURES WILL CLIMB FROM INTO THE 70S ON
TUESDAY AND INTO THE 80S FOR WEDNESDAY AND THURSDAY. RECORD HIGH
TEMPERATURES LOOK TO BE IN DANGER ON THURSDAY WITH HIGHS CURRENTLY
FORECAST IN THE MID 80S...BUT MIX DOWN POTENTIAL HINTS AT SLIGHTLY
HIGHER. RECORDS FOR THURSDAY RANGE FROM 89 IN MILES CITY TO 84 IN
BILLINGS. AS RIDGE SHIFTS SLOWLY EASTWARD SOUTHWEST FLOW ALOFT
BUILDING INTO THE AREA WILL INCREASE THE CHANCE OF ISOLATED TO
SCATTERED THUNDERSTORMS DEVELOPING OVER THE MOUNTAINS AND DRIFTING
INTO THE PLAINS FOR THURSDAY AFTERNOON AND EVENING.

HYDROLOGY...THE WARM TEMPERATURES FORECAST THIS WEEK ARE EXPECTED
TO INCREASE THE RATE OF SNOW MELT OVER AREA MOUNTAINS. THIS
SHOULD RESULT IN SIGNIFICANTLY INCREASED FLOWS ON AREAS STREAMS
AND RIVERS BY LATE WEEK. LATEST RIVER FORECASTS SHOW 5 TO 10 TIMES
THE CURRENT FLOWS DEVELOPING BY FRIDAY AND SATURDAY AT MANY
LOCATIONS ON AREA RIVERS. AT THIS POINT FORECASTS REMAIN WELL
BELOW FLOOD STAGE AT ALL LOCATIONS AND THE LACK OF SNOW PACK
BELOW 8000 FEET CERTAINLY SUPPORTS THIS. FOR THOSE LIVING NEAR
WATERWAYS HOWEVER THIS IS THE LAST FEW DAYS TO GET ANY PREPARATIONS
MADE BEFORE RUNOFF SEASON GETS GOING. FOR THOSE PLANNING
RECREATION ACTIVITIES ON WATERWAYS THIS WEEKEND BE PREPARED FOR
CHANGING CONDITIONS AND SIGNIFICANTLY HIGHER FLOWS. CHAMBERS

.LONG TERM...VALID FOR FRI...SAT...SUN...MON...

EXTENDED FORECAST MODELS CONTINUE TO ADVERTISE THE UPPER LEVEL
RIDGE BREAKING DOWN AND SHIFTING EAST ON FRIDAY AS A STRONG UPPER
LOW PRESSURE SYSTEM MOVES INTERIOR OF CALIFORNIA...TRACKING
NORTHEAST INTO SOUTHERN WYOMING BY LATE SATURDAY. THE APPROACH OF
THIS SYSTEM LOOKS TO DRAG DOWN COOLER LOW LEVEL AIR FROM CANADA
FRIDAY AFTERNOON...WITH A STRONG FRONTAL PASSAGE FORECAST BY ALL
MODELS WITH UPSLOPE NORTHERLY FLOW INCREASING PRECIPITATION
CHANCES UNDER AN INCREASING DIFFLUENT SOUTHERLY FLOW ALOFT. GFS
ENSEMBLE AND ECMWF KEEP THE SYSTEM JUST A BIT SOUTH OF THE SWEET
SPOT FOR PRECIPITATION ACROSS OUR AREA SATURDAY AND SUNDAY...WHILE
THE OPERATIONAL GFS IS TRACKING FURTHER NORTH. LATEST ENSEMBLE
GUIDANCE SUGGESTING LIKELY POPS OVER SOUTHERN TIER OF THE FORECAST
AREA WHILE CHANCE POPS WILL RESIDE FURTHER NORTH.

RECENT STORMS OF THIS TYPE HAVE TRENDED FURTHER SOUTH THAN
GUIDANCE AT THIS FORECAST TIME FRAME AND MODELS HAVE GENERALLY
STRUGGLED WITH THESE BIG SYSTEMS ACROSS OUR AREA. SO WHILE POPS
REFLECT THE CURRENT ENSEMBLE GUIDANCE...CONFIDENCE REMAINS LOWER
THAN AVERAGE FOR A SYSTEM 5 DAYS OUT. WRAPPED UP SYSTEMS SUCH AS
THE ONE FORECAST USUALLY SLOW DOWN WITH TIME AND WITH IT RUNNING
INTO A BLOCKING RIDGE WOULD EXPECT A SLOWER SOLUTION TO DEVELOP
GOING FORWARD. THE OMEGA BLOCK THAT THE SYSTEM RUNS INTO ALSO
OPENS THE POSSIBILITY THAT THE UPPER LOW WILL UNDERCUT THE RIDGE
AND STAY WELL SOUTH OF THE AREA ALTOGETHER. SO A LOT OF
UNCERTAINTY INVOLVED AND WOULD EXPECT FURTHER CHANGES TO THE
FORECAST WILL BE NEEDED GOING FORWARD...POSSIBLY SIGNIFICANT
CHANGES.

BY EARLY NEXT WEEK MODELS FILL AND LIFT THE UPPER LOW TO THE
NORTHEAST AND BRING A NORTHWEST FLOW PATTERN INTO THE AREA THROUGH
MID WEEK. BUT GIVEN THE INCONSISTENCIES INHERENT WITH THE WEEKEND
SYSTEM KEPT FORECAST NEAR CLIMO FOR PRECIPITATION AND
TEMPERATURES.

&&

.AVIATION...

VFR CONDITIONS WITH NO AVIATION HAZARDS EXPECTED THROUGH TUESDAY.
CHAMBERS

&&

.PRELIMINARY POINT TEMP/POPS...

    TUE     WED     THU     FRI     SAT     SUN     MON
-----------------------------------------------------------
BIL 045/077 048/084 051/085 055/069 046/060 043/065 044/065
    00/U    00/U    00/B    13/T    55/W    42/W    33/W
LVM 038/077 042/080 045/081 046/066 042/060 038/066 040/066
    00/U    01/U    11/B    24/T    54/W    42/W    33/W
HDN 039/077 042/083 044/086 046/072 042/063 039/068 041/065
    00/U    00/U    00/U    13/T    54/W    42/W    22/W
MLS 045/078 048/083 049/087 054/079 047/066 043/069 044/066
    00/U    00/U    00/U    12/T    43/T    32/W    22/W
4BQ 041/076 043/083 046/087 048/080 046/062 041/065 041/065
    00/U    00/U    00/U    13/T    54/T    42/W    22/W
BHK 040/075 044/081 045/085 048/080 044/064 040/065 041/064
    00/U    00/U    00/U    02/T    43/T    32/W    22/W
SHR 038/072 039/079 042/083 044/071 041/057 037/063 038/062
    00/U    00/U    00/U    13/T    66/W    64/W    33/W

&&

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

&&

$$
WEATHER.GOV/BILLINGS



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