Area Forecast Discussion
Issued by NWS Billings, MT

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000
FXUS65 KBYZ 010927
AFDBYZ

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BILLINGS MT
327 AM MDT WED JUL 1 2015

.SHORT TERM...VALID FOR TDY AND THU...

STRONG SHORTWAVE WAS EXITING SOUTHEAST BRITISH COLUMBIA THIS
HOUR. THIS WAVE WILL BE THE WEATHER MAKER TODAY. NORTHWEST FLOW
WILL SEND THE SHORTWAVE INTO EASTERN MONTANA THIS AFTERNOON. A
70KT JET MAX WILL ACCOMPANY THIS ENERGY FOR STRONG ASCENT. THE
SHORTWAVE DOES LOOK RATHER IMPRESSIVE ON WATER VAPOR AND WAS
PRODUCING QUITE A BIT OF CONVECTION THIS HOUR. THE SET UP OVER THE
EAST WAS A LITTLE DIFFERENT FROM YESTERDAY WITH THE ABSENCE OF A
LOW LEVEL FORCING BOUNDARY. MODELS KEEP THE SURFACE TROUGH MAINLY
EAST OF THE STATE LINE TODAY AND LEAVE LOW LEVEL WINDS IN A NORTH
TO NORTHWEST DIRECTION. SPEED SHEAR WAS GOOD...BUT DIRECTIONAL
SHEAR NOT AS GOOD AS YESTERDAY. DEWPOINTS ARE PROJECTED A LITTLE
LOWER TODAY OVER THE EAST WITH MID TO UPPER 50S...POSSIBLY AROUND
60 AT BAKER. ENOUGH PRESENT THOUGH WITH THE STRENGTH OF THE WAVE
TO GENERATE A FEW SEVERE STORMS. THE MOST LIKELY LOCATION WILL BE
FROM ROSEBUD COUNTY EASTWARD. WILL MENTION IN THE ZONES. CENTRAL
AND WESTERN ZONES WILL BE A LITTLE DRIER AT LOWER LEVELS...WITH
DEWPOINTS IN THE UPPER 40S. WILL KEEP THE ISOLATED POP MENTION
OVER CENTRAL ZONES AND ALONG THE FOOTHILLS.

THE CHANCE FOR STRONG STORMS OVER THE EAST WILL LINGER INTO THE
EVENING HOURS AS THE MAIN SHORTWAVE DOES NOT CLEAR THE EAST UNTIL
MIDNIGHT. WILL GRADUALLY TAPER OFF POPS FROM WEST TO EAST
OVERNIGHT. MID LEVEL HEIGHTS BUILD INTO THE WEST A BIT ON
WEDNESDAY WHICH KEEPS WEAK SHORTWAVE ENERGY RIDING OVER EASTERN
MONTANA FOR LOW POPS THERE. HAVE INCLUDED LOW POPS OVER NORTHWEST
ZONES WEDNESDAY NIGHT AS A SHORTWAVE SWINGS ACROSS WASHINGTON AND
INTO THE AREA. WILL CONFINE THE POPS TO THE NORTHWEST HALF OF THE
AREA. HIGHS SHOULD BE A LITTLE COOLER TODAY WITH LOW LEVEL
NORTHERLY FLOW...BUT LOW 90S STILL LOOK ON TRACK GIVEN 850MB
TEMPERATURES AROUND 29C. THURSDAY SHOULD HAVE HIGHS HELD IN THE
MID TO UPPER 80S AS PERSISTENT LOW LEVEL NORTH WINDS SUPPRESS THE
WARMER 850MB TEMPERATURES TO THE SOUTH. TWH

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

MODELS AGREEMENT HAS IMPROVED GREATLY...WITH REGARD TO THE
OVERALL PATTERN. THAT SAID...THERE ARE STILL DETAILS THAT ARE OUT
OF AGREEMENT THAT MAKE MORE DETAILED FORECAST DIFFICULT...MOST
SIGNIFICANTLY TIMING.

THE EXTENDED PERIOD STARTS OUT DRY ON FRIDAY...WITH SHORTWAVE
RIDGING MARKING THE BEGINNING OF A WARMING TREND AS TEMPS CLIMB
BACK ABOVE 90. THE WARM UP CONTINUES INTO SATURDAY...WITH
POTENTIAL ENHANCEMENT OF WARMUP IN PREFRONTAL ENVIRONMENT DRIVING
TEMPS BACK INTO UPPER 90S. TIMING ISSUES COME INTO PLAY RIGHT AWAY
SATURDAY...WITH THE FRONTAL PASSAGE...AND APPEARS THAT MODELS HAVE
FLIP FLOPPED FROM PREVIOUS RUN. THE GFS IS FASTER BRINGING THE
SYSTEM THROUGH THE REGION BY ABOUT 12HRS. THE ECMWF DOES HOWEVER
SEEM TO MOVE THE SYSTEM OUT MORE QUICKLY. THE GFS ALSO APPEARS TO
BE THE COOLER OF THE MODELS. ADJUSTED POPS TO ACCOUNT FOR TIMING
OF THE GFS...ADDING POPS SATURDAY AFTERNOON THROUGH SATURDAY
NIGHT. ALSO CARRIED POPS THROUGH SUNDAY NIGHT...FOR LATER EXIT OF
THE ECMWF. THIS WILL NEED PARING BACK AS TIMING COMES TOGETHER.
UPPER LEVEL FLOW REMAIN GENERALLY DRY NORTHWESTERLY FOR THE NEXT
FEW DAYS. MEANWHILE UPPER LOW OFF THE COAST OF CALIFORNIA
CONTINUES TO PUMP MOISTURE INTO SOUTHERN ZONES AS IT SLOWLY PUSHES
EASTWARD. CARRIED POPS INTO MOUNTAINS AND NEAR FOOTHILLS REGIONS
THROUGH TUESDAY. TEMPS THROUGH THIS PERIOD WILL STILL BE A BIT
ABOVE AVERAGE...WITH HIGHS IN THE MID 80S...BUT MUCH MORE
ENJOYABLE.

AT THIS POINT THE IMPROVED MODEL AGREEMENT DISAPPEARS...SO HAVE
CARRIED CLIMO TYPE POPS THROUGH THE END THE PERIOD. AAG

&&

.AVIATION...

FOG PERSISTS IN AND AROUND BAKER THIS MORNING...WITH CLEARING
EXPECTED BY LATE MORNING. GUSTY WINDS AND THUNDERSTORM CHANCES
WILL RETURN THIS AFTERNOON/EVENING...SOME STORMS MAY BE
SEVERE...ESPECIALLY IN EASTERN MONTANA. EXPECT VIS REDUCTIONS IN
AND AROUND THUNDERSTORM ACTIVITY. AAG

&&

.PRELIMINARY POINT TEMP/POPS...

    TDY THU     FRI     SAT     SUN     MON     TUE
-------------------------------------------------------
BIL 092 062/087 061/091 064/097 061/082 060/085 061/086
    2/T 21/U    21/B    11/U    22/T    22/T    22/T
LVM 092 053/089 053/092 056/098 055/083 053/084 054/086
    1/U 11/U    21/U    11/B    22/T    23/T    32/T
HDN 093 059/089 058/093 062/100 060/085 059/087 060/088
    2/T 21/B    11/U    11/U    22/T    22/T    22/T
MLS 090 061/086 060/091 064/099 060/083 058/083 059/086
    3/T 41/B    01/B    12/T    33/T    12/T    22/T
4BQ 088 060/085 058/088 063/097 061/083 059/084 060/085
    2/T 31/B    11/U    12/T    22/T    12/T    22/T
BHK 083 058/081 056/086 060/095 058/080 054/079 055/081
    3/T 52/T    11/U    12/T    33/T    22/T    22/T
SHR 090 057/084 055/087 058/095 058/081 055/081 056/083
    2/T 22/T    11/U    11/U    22/T    33/T    22/T

&&

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

&&

$$
WEATHER.GOV/BILLINGS



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