Area Forecast Discussion
Issued by NWS Billings, MT

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000
FXUS65 KBYZ 290907
AFDBYZ

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BILLINGS MT
307 AM MDT MON JUN 29 2015

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

THE HOT UPPER RIDGE THAT HAS BEEN GIVEN THE NORTHERN ROCKIES
TEMPERATURES IN THE 90S THE LAST SEVERAL DAYS WILL SLOWLY SLIDE
EAST TODAY. THIS WILL PLACE THE WEST HALF OF SOUTH CENTRAL MONTANA
UNDERNEATH THE STRONGEST SUBSIDENCE OF THE RIDGE AND RIGHT
UNDERNEATH THE THERMAL RIDGE. THIS SHOULD TRANSLATE INTO THE
HOTTEST DAY OF THIS STRETCH. LOW LEVEL EASTERLY WINDS AND A FEW
CLOUDS FROM CONVECTION TO THE WEST MAY PREVENT WIDESPREAD 100
DEGREES READINGS...BUT UPPER 90S WILL CERTAINLY BE REACHED.

THE RIDGE WILL FLATTEN THIS EVENING BY SHORTWAVE ENERGY RIDING UP
AND OVER IT FROM OFF THE OREGON COAST. A WEAKER WAVE IS PROGGED BY
THE GFS TO UNDERCUT THE MAIN WAVE AND SLIDE ACROSS WESTERN AND
CENTRAL MONTANA. THIS WILL PUSH A WEAK COLD FRONT INTO THE WEST
EARLY THIS EVENING...CENTRAL ZONES LATE THIS EVENING AND EASTERN
ZONES OVERNIGHT. TIMING HAS BEEN SLOWED A BIT MORE FROM THE
MODELS. THE SHORTWAVE WILL KICK OFF A FEW STORMS OVER THE WEST AS
EARLY AS THIS AFTERNOON...BUT CURRENT TRENDS WOULD SUGGEST STORMS
MAY HOLD OFF UNTIL THIS EVENING. ANY STORM THAT DOES FORM COULD
HAVE THE POTENTIAL OF PRODUCING STRONG WIND GUSTS WITH INVERTED V
SOUNDINGS AND PRECIPITABLE WATER AMOUNTS AROUND .75 ABOVE THE
MIXED LAYER. THESE GUSTY WINDS COULD MAKE IT AS FAR EAST AS
BILLINGS BY LATE EVENING...BUT BY THAT TIME...SOME COOLING WILL BE
EXPERIENCED IN THE SUB CLOUD LAYER AND COULD LIMIT THE GUSTINESS.
WILL MENTION GUSTY WINDS WEST OF BILLINGS.

THE SOUTHERN SHORTWAVE EXITS THE EAST OVERNIGHT...BUT THE MAIN
NORTHERN WAVE WAS SLOWER AND SLIDES SOUTHEAST INTO SOUTHEAST
MONTANA TUESDAY AFTERNOON. THE MAIN PUSH OF HIGHER PRECIPITABLE
WATER AMOUNTS...(OVER AN INCH)...GETS SHOVED INTO THE DAKOTAS
EARLY TUESDAY BUT A SECONDARY PUSH OF PWATS AROUND .75 LINGERS IN
THE EAST THROUGH THE AFTERNOON. WILL KEEP THE MENTION OF SCATTERED
THUNDERSTORMS OVER THE EAST. 850MB WINDS INCREASE TO 25-30 KTS
OVER MUCH OF THE AREA ON TUESDAY. WITH DRY MID LEVEL AIR SWEEPING
IN FOR MOST LOCATIONS AS THE RIDGE FLATTENS...THIS WILL CREATE A
BREEZY DAY. MID LEVEL HEIGHTS WERE STILL BE HIGH ENOUGH TO PRODUCE
MAX TEMPERATURES IN THE MID 90S ON TUESDAY...DESPITE THE WEAK COLD
FRONTAL PASSAGE TONIGHT. HUMIDITIES WILL FALL INTO THE TEENS WITH
GUSTY NORTHWEST WINDS. WILL STRONGLY WORD THE FIRE WEATHER
FORECAST FOR HEIGHTENED AWARENESS. THE SHORTWAVE ENERGY WILL SWEEP
OUT OF THE EAST TUESDAY EVENING...LEAVING THE FORECAST DRY
OVERNIGHT. TWH

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

MADE SEVERAL CHANGES TO THE EXTENDED FORECAST PERIOD THIS
MORNING...AS UNSTABLE NORTHWESTERLY FLOW ALOFT PERSIST THROUGH
THE WEEK. TEMPERATURES WILL MODERATE SOME FROM TEMPS SEEN OVER THE
WEEKEND AND INTO THE EARLY PART OF THE WEEK...BUT THICKNESS
VALUES DO STAY PRETTY HIGH...SO TEMPS WILL LINGER IN THE MID 80S
TO AROUND 90 DEGREE MARK.

AS FOR PRECIPITATION CHANCES ACROSS THE REGION...SEVERAL
SHORTWAVES CROSS THE REGION THROUGHOUT THE EXTENDED FORECAST
PERIOD. THE DIFFICULTY IS THAT THERE ARE MANY MODEL
DIFFERENCES...IN PRECIP COVERAGE...TIMING...AND INTENSITY...BUT
GENERAL AGREEMENT ON THE STRONGER WAVES COMING INTO THE AREA
WEDNESDAY THROUGH THURSDAY...SATURDAY...AND MONDAY. HAVE EXPANDED
SHOWER AND THUNDERSTORM COVERAGE FOR EACH OF THESE WAVES THAT
APPEAR STRONGEST IN THE MODELS AT THIS TIME. BEST POTENTIAL
APPEARS IN THE EAST FOR EACH OF THESE WAVES...ESPECIALLY ON
SATURDAY...AS DOWNSLOPE FLOW SHOULD IMPACT THE WEST TO SOME
DEGREE THROUGHOUT THE PERIOD. MODEL DIFFERENCES HAVE NECESSITATED
KEEPING POPS LOW AT THIS TIME FOR EACH OF THESE EVENTS.

IN PERIODS IN BETWEEN MAIN WAVES...WEAKER SHORTWAVES CAN BE SEEN
IN THE FLOW. AS MENTIONED...DOWNSLOPE FLOW WILL PLAY A PART
THROUGHOUT THE PERIOD...ESPECIALLY IN THE WEST...BUT IT COULD BE
ARGUED THAT BROADBRUSH ISOLATED TYPE POPS WOULD NOT BE OUT OF LINE
FOR AREAS SAY EAST OF BILLINGS. HAVE KEPT THESE PERIOD DRY FOR
NOW...BUT WILL BE WORTH WATCHING CLOSELY. AAG

&&

.AVIATION...

SHOWERS AND THUNDERSTORMS CONTINUE TO FIRE IN EXTREME SOUTHEAST
MONTANA THIS MORNING. STORMS ARE PRODUCING LOCALIZED REDUCED
VIS IN HEAVIER RAIN AND GUSTY WINDS...BUT VFR CONDITIONS AND
LIGHT WINDS WILL PREVAIL ACROSS THE REGION TODAY. AN UPPER LEVEL
DISTURBANCE WILL TRAVERSE THE REGION THIS EVENING AND
OVERNIGHT...BRINGING SCATTERED SHOWERS AND ISOLATED
THUNDERSTORMS. LOCALIZED MVFR TO IFR CONDITIONS ARE POSSIBLE IN
HEAVIER PRECIP. PERIODIC MOUNTAIN OBSCURATIONS WILL DEVELOP THIS
MORNING...AND PERSIST THROUGH THE DAY. AAG

&&

.PRELIMINARY POINT TEMP/POPS...

    TDY TUE     WED     THU     FRI     SAT     SUN
-------------------------------------------------------
BIL 100 070/096 064/091 063/086 061/090 064/090 061/086
    0/U 22/T    12/T    21/U    11/U    11/U    11/B
LVM 100 059/094 054/092 053/088 053/091 055/091 052/088
    2/T 32/T    12/T    11/U    11/U    11/B    11/B
HDN 102 065/098 060/093 061/088 060/092 062/093 060/089
    0/G 22/T    12/T    21/U    11/U    11/U    11/B
MLS 099 069/097 063/087 061/085 059/088 062/091 059/085
    0/U 12/T    12/T    22/T    11/U    12/T    21/B
4BQ 097 065/094 063/087 061/085 058/086 062/090 059/085
    0/U 12/T    12/T    22/T    11/U    12/T    21/B
BHK 094 063/093 060/082 058/081 056/083 058/087 057/082
    0/U 03/T    22/T    42/T    11/U    12/T    22/T
SHR 095 060/093 058/087 057/083 054/084 056/087 056/083
    0/U 12/T    22/T    22/T    11/U    12/T    21/B

&&

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

&&

$$
WEATHER.GOV/BILLINGS



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