Area Forecast Discussion
Issued by NWS Billings, MT

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FXUS65 KBYZ 302247
AFDBYZ

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE BILLINGS MT
447 PM MDT TUE JUN 30 2015

.UPDATE...

SENT OUT A QUICK UPDATE TO INCLUDE A TORNADO WATCH FOR FALLON
COUNTY THROUGH 1 AM MDT. AFTER AN INITIAL PUSH OF WEST/NORTHWEST
DRY AIR...A MOIST EASTERLY SURFACE FLOW WILL POSSIBLY RETURN
LATER THIS EVENING. THIS COMBINED WITH GOOD SHEAR WILL ALLOW FOR
THE POSSIBILITY OF SEVERE THUNDERSTORMS CLOSE TO THE DAKOTA
BORDER. HOOLEY

&&

.SHORT TERM...VALID FOR WED AND THU...

STRONG RIDGE ALOFT REMAINS ANCHORED OVER THE CENTRAL ROCKIES AND
GREAT BASIN. SHORTWAVE WHICH ROUNDED THIS RIDGE IS IN EASTERN
MONTANA WITH DRIER AIR AND SUBSIDENCE IN ITS WAKE AFFECTING OUR
WEST. DEW POINTS HAVE FALLEN TO THE 40S WITH GUSTY NW WINDS IN THE
WELL-MIXED BOUNDARY LAYER ACROSS OUR WEST...KILLING ANY CHANCE OF
CONVECTION EXPECT OVER OUR SOUTHERN MTS AND FOOTHILLS INTO THIS
EVENING. WIND SHIFT IS THROUGH MILES CITY BUT HAS NOT REACHED
BAKER YET. THERE REMAINS AN OPPORTUNITY FOR A COUPLE STRONG TO
SEVERE STORMS GENERALLY FROM BAKER TO EKALAKA IN THE DEEPLY
UNSTABLE ENVIRONMENT ALONG THE DAKOTAS BORDER...WITH NEAR 50 KTS
OF EFFECTIVE BULK SHEAR. WINDOW OF OPPORTUNITY IS CLOSING IN THIS
AREA AS WIND SHIFT SHOULD REACH ND/SD SOON...WITH SUBSIDENCE
BEHIND SHORTWAVE EXPECTED TO ARRIVE THIS EVENING. A SHIFT BACK TO
NE WINDS IS ANTICIPATED FOR OUR NORTHEAST PARTS LATER THIS
EVENING...AND ADVECTION OF LOW LEVEL MOISTURE POOLED IN ND MAY
ALLOW FOG TO DEVELOP NEAR BAKER AND MILES CITY BY EARLY WEDNESDAY.
WILL ALSO KEEP ISOLATED POPS GOING IN OUR NORTHEAST TOMORROW
MORNING AS WE WILL BEGIN TO SEE ASCENT SPREAD IN FROM NEXT
SHORTWAVE ALONG THE WA/BC COAST...WITH SUFFICIENT ELEVATED
INSTABILITY EAST OF THE SFC TROF.

GREATER POTENTIAL FOR CONVECTION EXISTS TOMORROW AFTERNOON AND
EVENING PER AFOREMENTIONED PAC NW ENERGY...ESPECIALLY IN OUR EAST
WHERE GREATER MOISTURE AND INSTABILITY WILL RESIDE. SPC HAS
HIGHLIGHTED OUR FAR EAST FOR A MARGINAL RISK OF SEVERE WX FOR DAY
2...WITH HAIL AND WIND BEING THE MAIN THREATS FOR ANY STORMS NEAR
PLACES SUCH AS MILES CITY...BAKER AND EKALAKA. WILL NEED TO
MONITOR THE EVOLUTION OF THE SFC BOUNDARY OVER THE NEXT 24 HOURS
AS THIS WILL INFLUENCE ANY SEVERE RISK. A FEW STORMS ARE STILL
POSSIBLE WEST OF THESE AREAS BUT DRIER AIR AND HIGHER CLOUD BASES
WILL HINDER THIS POTENTIAL WHILE ALLOWING FOR POTENTIALLY GUSTY
SFC WINDS.

ANOTHER WEAK PACIFIC SHORTWAVE WILL CLIP THE AREA THURSDAY NIGHT.
AIRMASS WILL BE DRIER BUT CANNOT DISCOUNT A FEW SHOWERS OR NON-
SEVERE STORMS.

TEMPS TOMORROW SHOULD BE A BIT COOLER THAN TODAY BUT WITH PLENTY
OF MIXING EXPECT HIGHS BACK INTO THE LOWER 90S AGAIN...WITH 80S IN
OUR FAR EAST. THURSDAY SHOULD BE THE COOLEST DAY WE HAVE SEEN IN
AWHILE WITH A PUSH OF COLD ADVECTION BEHIND WEDNESDAY SYSTEM.
HIGHS SHOULD STAY UNDER 90F ON THURSDAY.

JKL

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

MODEL AGREEMENT IS DEGRADED THIS CYCLE AS FRIDAY HAS A WARMUP IN
NORTHWEST FLOW ALOFT AND SATURDAY WARMS STRONGLY IN A PREFRONTAL
ENVIRONMENT. THE DIFFERENCES IN THE MODELS SHOW UP ALREADY
SATURDAY EVENING WITH THE ECMWF SHOWING A FASTER FRONTAL PASSAGE
SATURDAY EVENING WITH A POLAR TYPE FRONT WITH THE GFS LOOKING
SLOWER WITH MORE OF A PACIFIC FRONT LOOK. THEN THE MODELS RETAIN
DIFFERENT SOLUTIONS WITH THE ECMWF WANTING TO TREND NORTHWESTERLY
FLOW TO PREVAIL THROUGH THE EXTENDED WHILE THE GFS DROPS ENERGY
INTO THE PACIFIC NORTHWEST AND GIVES A MORE WEST SOUTHWESTERLY
FLOW COMPONENT.

SATURDAY NIGHT IS THE MOST CRITICAL PERIOD OF THE EXTENDED AS WARM
AND BREEZY CONDITIONS ARE EXPECTED AFTER A HOT AND DRY 4TH. MADE
A COUPLE OF ADJUSTMENTS TO THE FORECAST TO DRY OUT A FEW PERIODS
IN THE LOWER ELEVATIONS AND INCREASED THE WINDS SATURDAY NIGHT.

BORSUM

&&

.AVIATION...

MOSTLY CLEAR CONDITIONS OVERNIGHT FOR MOST OF THE AREA. ISOLATED
THUNDERSTORMS STILL POSSIBLE ALONG THE MONTANA DAKOTA BORDER
UNTIL EARLY THIS EVENING. FOG AND SMOKE REDUCING VISIBILITY WILL
WORK INTO NORTHERN PARTS OF SOUTHEAST MONTANA LATER TONIGHT.
BORSUM
&&

.PRELIMINARY POINT TEMP/POPS...

    WED     THU     FRI     SAT     SUN     MON     TUE
-----------------------------------------------------------
BIL 063/092 062/087 061/091 064/098 062/085 062/085 063/088
    12/T    21/U    11/U    11/U    12/T    22/T    22/T
LVM 053/092 053/089 053/092 055/097 054/087 054/086 056/089
    11/U    11/U    21/U    11/B    22/T    22/T    22/T
HDN 060/093 059/089 058/093 062/100 060/087 060/087 062/090
    12/T    21/B    11/U    11/B    11/B    12/T    22/T
MLS 064/090 061/086 060/089 063/099 060/085 059/085 062/085
    13/T    41/B    11/U    11/B    11/B    12/T    22/T
4BQ 061/088 060/085 058/087 063/097 062/085 061/084 062/085
    12/T    32/T    11/U    11/U    11/B    12/T    22/T
BHK 059/083 058/081 056/084 059/094 059/081 056/080 057/080
    33/T    52/T    11/U    11/U    11/B    12/T    22/T
SHR 058/090 057/084 055/086 057/095 058/083 056/083 059/085
    22/T    22/T    11/U    11/U    12/T    22/T    22/T

&&

.BYZ WATCHES/WARNINGS/ADVISORIES...
MT...TORNADO WATCH 380 IN EFFECT UNTIL 1 AM MDT WEDNESDAY FOR ZONE
      33.
WY...NONE.

&&

$$
WEATHER.GOV/BILLINGS


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