Area Forecast Discussion
Issued by NWS Billings, MT

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000
FXUS65 KBYZ 181957
AFDBYZ

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BILLINGS MT
157 PM MDT FRI JUL 18 2014

.SHORT TERM...VALID FOR SAT AND SUN...

WEEKEND WILL FEATURE ABOVE NORMAL TEMPERATURES WITH MAINLY DRY
WEATHER. CONVECTION HAS BEEN SLOWER TO FIRE THIS AFTERNOON AS
CLOUD COVER HAS INHIBITED A RAPID WARMUP. HOWEVER...LATEST RAP
SHOWED SURFACE CAPES AROUND 500 J/KG WITH NO CIN OVER THE SW PART
OF THE AREA. SURFACE CONVERGENCE AND ENERGY MOVING THROUGH THE
FLOW ON WATER VAPOR IMAGERY...SHOULD INITIATE STORMS OVER THE HIGH
TERRAIN OVER THE NEXT COUPLE OF HOURS.

A WAVE MOVING INTO NW MT THIS AFTERNOON WILL CROSS THE STATE
TONIGHT WITH WEAK Q-VECTOR CONVERGENCE. THE WAVE WILL DRIVE A WEAK
COLD FRONT INTO THE EASTERN ZONES BY 12Z SAT. WEAK FORCING WILL
KEEP STORMS ISOLATED TONIGHT. STORMS WILL BE AIDED BY CAPES
BETWEEN 500 AND 1000 J/KG THIS EVENING AND PRECIPITABLE WATERS
AROUND 1 INCH AHEAD OF THE FRONT. HAVE USED A COMBINATION OF THE
WRF AND SREF TIMING FOR CONVECTION. GUSTY WINDS WILL NOT BE OUT OF
THE QUESTION WITH ANY THUNDERSTORMS GIVEN THAT MOISTURE WILL BE
HIGH-BASED. LOCALLY HEAVY DOWNPOURS WILL BE POSSIBLE E OF THE
FRONT OVERNIGHT GIVEN THE HIGH PRECIPITABLE WATERS.

MODEL TIMING WITH THE FRONT WAS SIMILAR ON SAT WITH MODELS ONLY
SLOWLY MOVING THE FRONT THROUGH SE MT. AIRMASS WILL DRY OUT DURING
THE DAY UNDER FAST WESTERLY FLOW...HOWEVER...A SLIGHT CHANCE OF
THUNDERSTORMS WILL LINGER FROM KMLS E AND SE. HIGH TEMPERATURES IN
THE 90S WITH COMBINE WITH RELATIVE HUMIDITIES IN THE TEENS AND
WELL-MIXED GUSTY W WINDS BEHIND THE FRONT TO HEIGHTEN FIRE WEATHER
CONCERNS. GIVEN THE CURRENT STATE OF THE FUELS...A HEADLINE WILL
CONTINUE TO SUFFICE IN THE FIRE WEATHER FORECAST FOR SAT/S
CONDITIONS.

ZONAL FLOW WILL CONTINUE OVER THE AREA SAT NIGHT AND SUN...BEFORE
TURNING MORE SW SUN NIGHT. SOME MOISTURE AND A WEAK SHORTWAVE WERE
FORECAST TO APPROACH THE SW MOUNTAINS SUN NIGHT...SUPPORTING LOW
POPS THERE. SUN WILL CONTINUE TO BE HOT WITH LOW HUMIDITIES...BUT
WILL NOT BE QUITE AS WINDY AS SAT. ARTHUR

.LONG TERM...VALID FOR MON...TUE...WED...THU...FRI...

THE EC 12Z RUN HAS TRENDED TOWARD THE GFS 12Z RUN THROUGH MID
WEEK INCREASING OUR CONFIDENCE WITH REGARD TO THE FIRST PART OF
THE EXTENDED PERIOD. THIS SHOWS A RIDGE AXIS OVER EASTERN MONTANA
WITH A SOMEWHAT MOIST PACIFIC SW FLOW INTO SW MONTANA BRINGING THE
OCCASIONAL WEAK DISTURBANCE INTO THE MOUNTAINS WITH A SLIGHT
CHANCE OF CARRYING SOME ISOLATED CONVECTION INTO THE PLAINS IN THE
EVENING. AFTER TUESDAY...A STRONG UPPER TROUGH OVER THE PACIFIC NW
BREAKS DOWN THE RIDGE AS IT TRACKS ALONG THE CANADIAN BORDER. THE
EC STILL CARRIES THE TRACK A LITTLE FURTHER NORTH THAN THE GFS AT
MIDWEEK...BUT GENERALLY STILL PLACING OUR FORECAST AREA IN A DRY
SLOTTED REGION. THIS IS SET UP FOR POTENTIALLY BEING A SIGNIFICANT
RIDGE CRASHER WHICH MAY LEAD TO FIRE WEATHER CONCERNS DEPENDING ON
FUELS STATUS NEXT WEEK. DRY AND SOMEWHAT COOLER CONDITIONS SHOULD
TAKE OVER BEHIND THE THURSDAY SYSTEM FOR FRIDAY AND INTO THE
WEEKEND. BT
&&

.AVIATION...

VFR WILL PREVAIL OVER THE FORECAST AREA INTO THE EVENING AND
OVERNIGHT HOURS. HOWEVER...A WEAK DISTURBANCE IN THE NW FLOW ALOFT
WILL PRODUCE ISOLATED SHOWERS AND POSSIBLY A STRAY THUNDERSTORM OR
TWO OVER THE REGION. THE BEST CHANCE OF A THUNDERSTORM IS OVER
THE BIG HORN MOUNTAINS NEAR KSHR BETWEEN 02Z AND 07Z. AN
ASSOCIATED COLD FRONT DRAGGED BEHIND THE DISTURBANCE WILL SHIFT
WINDS TO THE WEST LATE TONIGHT AND INTO SATURDAY MORNING. BT

&&

.PRELIMINARY POINT TEMP/POPS...

    SAT     SUN     MON     TUE     WED     THU     FRI
-----------------------------------------------------------
BIL 061/094 062/094 063/089 062/092 064/093 061/085 057/086
    20/N    01/U    12/T    21/U    12/T    22/T    21/U
LVM 054/091 055/091 055/084 055/089 055/089 053/083 050/085
    20/N    01/N    12/T    22/T    22/T    22/T    21/U
HDN 059/096 059/096 061/092 061/093 063/095 061/088 057/087
    20/U    01/U    12/T    21/U    12/T    22/T    21/U
MLS 062/095 064/094 065/093 064/092 066/095 063/087 059/087
    22/T    01/U    12/T    21/U    12/T    22/T    21/U
4BQ 061/094 061/094 063/093 063/092 064/095 063/088 058/086
    21/U    01/U    12/T    21/U    12/T    22/T    21/U
BHK 057/092 060/092 062/093 061/088 061/091 060/085 056/084
    22/T    11/U    12/T    22/T    12/T    22/T    21/U
SHR 056/092 055/091 058/089 057/090 060/093 057/087 053/085
    20/U    01/U    12/T    21/U    12/T    22/T    21/U

&&

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

&&

$$
WEATHER.GOV/BILLINGS


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