Area Forecast Discussion
Issued by NWS Billings, MT

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000
FXUS65 KBYZ 241858
AFDBYZ

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BILLINGS MT
1258 PM MDT THU JUL 24 2014

.SHORT TERM...VALID FOR FRI AND SAT...

THE QUESTION THAT STILL REMAINS IS JUST HOW STRONG THE CAPPING
WILL BE AHEAD OF THE SURFACE FRONT THIS AFTERNOON. HOWEVER...THE
TIMING OF THE SURFACE FRONT IS OPTIMALLY TIMED WITH DIURNAL
DESTABILIZATION TO WARRANT SOME CONCERN OVER WHETHER THUNDERSTORM
DEVELOP WILL OCCUR ALONG THE FRONT...ESPECIALLY EAST OF BILLINGS.
HOWEVER...WITH STRONG FORCING FROM THE FRONTOGENESIS AND THE QG
DIVERGENCE ALOFT WITH THE UPPER LOW...FEEL THIS WILL HELP SUPPORT
BREAKING THE CAP...AT LEAST ALONG THE NORTHERN TIER OF COUNTIES
WHERE THE CAP WILL NOT BE AS STRONG. MODELS REMAIN CONFLICTED ON
WHETHER THIS CONVECTIVE DEVELOP WILL OCCUR ALONG THE FRONT. WHILE
THE GFS/NAM/SREF SOLUTIONS PRODUCE NEXT TO NO CONVECTION FOR
US...THE EC REMAINS STEADFAST IN SHOWING DEVELOPMENT ALONG AND
EAST OF A LINE FROM HARLOWTON TO BILLINGS TO SHERIDAN...WHICH IT
HAS BEEN SHOWING FOR THE LAST SEVERAL DAY. THE 00Z SSEO RUN
SUPPORTS THE EC SOLUTION...WITH THE MAJORITY OF MEMBERS DEVELOPING
CONVECTION EAST OF BILLINGS...AND SUPPORTING A DAMAGING WIND
THREAT WITH THOSE STORMS. GIVEN THE RELATIVELY SURPRISING EASE
WITH WHICH WE HAVE SEEN STORMS OVER THE LAST FEW DAYS...EVEN ON
DAYS WHEN THE CAPPING WAS FAIRLY STRONG...WE ARE INCLINED TO SIDE
WITH THE EC/SSEO SOLUTION. THUS HAVE INCREASED POPS
SLIGHTLY...ADDED SEVERE MENTION IN THE EAST...AND INCREASED
MESSAGING IN THE HWO AND WEATHER STORY GRAPHICS.

FRIDAY AND SATURDAY ARE SHAPING UP TO BE COOLER AND DRY BEHIND THE
COLD FRONT PASSAGE THIS EVENING. 700 MB TEMPERATURES FALL TO
AROUND +10C ON FRIDAY AFTERNOON...WITH A SLIGHTLY COOLER PUSH BY
SATURDAY AFTERNOON OF ABOUT +8C. THIS WILL YIELD HIGH TEMPERATURES
IN LOW TO MID 80S. FRIDAY AND SATURDAY WILL BOTH MIX A DECENT
NORTHWEST WIND AS THE UPPER LEVEL LOW SLOWLY TRACKS ACROSS
SOUTHERN CANADA. THE NORTHWEST WINDS WILL HELP US REALIZE MAXIMUM
POTENTIAL HEATING WITH DOWNSLOPE FLOW. MUCH DRIER AIR PUSHES IN
BEHIND THE FRONT AS WELL...AND THE FORECAST IS FOR COMPLETELY DRY
CONDITIONS THROUGH THE WEEKEND.

CHURCH

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

THE LARGE-SCALE PATTERN ACROSS THE UNITED STATES WILL BE LOCKED IN
ON A 500-MB TROUGH OVER THE EAST AND RIDGING IN THE WEST. GUIDANCE
AGREES WELL ON THIS SCENARIO WITH SOUTHERN MT AND NORTH CENTRAL WY
WEATHER CONTROLLED BY THE RIDGE PART OF THE SITUATION FOR A MAINLY
DRY AND WARM PERIOD. WE RELIED ON CONTINUITY AND SMALL ADJUSTMENTS
TOWARD THE WELL-CLUSTERED 12 UTC MULTI-MODEL CONSENSUS FOR GRIDDED
FORECAST ELEMENTS IN THE LONG TERM FORECAST. THUS...WE ARE CALLING
FOR HIGHS IN THE 80S F WITH LIGHT WINDS AND DRY WEATHER TO END THE
WEEKEND AND A WARMING TREND BACK TOWARD 90 F NEXT WEEK AS THE 500-
MB RIDGING BUILDS EASTWARD A BIT. RECENT RUNS OF THE ECMWF AND GFS
DO SUGGEST A BIT OF MONSOONAL MOISTURE WILL MANAGE TO UNDERCUT THE
RIDGE NEXT WEEK...LEADING TO A LOW CHANCE OF SPOTTY CONVECTION. WE
BELIEVE EVEN THIS LOW CHANCE OF SHOWERS AND STORMS WILL BE FOCUSED
NEAR THE MOUNTAINS AND FOOTHILLS...BUT GIVEN SUBTLE TRENDS SEEN IN
GFS AND ECMWF SOLUTIONS TOWARD A BIT MORE COVERAGE OVER THE PLAINS
WE DID SPREAD A SLIGHT CHANCE OF STORMS NORTH AND EAST TO BILLINGS
AND LAME DEER TUE AFTERNOON AND EVENING. IT/S POSSIBLE THAT SLIGHT
CHANCE POPS WILL BE NEEDED IN OTHER PERIODS OR PLACES...BUT WE DID
NOT ADD ANY NOW SINCE THE MAIN MESSAGE DURING THIS PERIOD IS FOR A
LARGELY DRY AND QUIET WEATHER REGIME. SCHULTZ

&&

.AVIATION...

A CHANCE OF THUNDERSTORMS EXISTS ACROSS SOUTHEASTERN MT FROM ABOUT
21 TO 03 UTC...AND IF ANY STORMS FORM THEY COULD BE SEVERE WITH 50
KT OR STRONGER WINDS...HAIL AND LOCAL IFR CONDITIONS. PASSAGE OF A
COLD FRONT WILL YIELD GUSTY AND SHIFTING WINDS BY EVENING OVER ALL
OF SOUTHERN MT AND NORTH CENTRAL WY...BUT VFR WEATHER WILL RULE IN
ALL AREAS OVERNIGHT AND ON FRIDAY BEHIND THE FRONT. SCHULTZ

&&

.PRELIMINARY POINT TEMP/POPS...

    FRI     SAT     SUN     MON     TUE     WED     THU
-----------------------------------------------------------
BIL 057/086 057/083 056/084 059/089 061/089 061/090 060/091
    10/U    00/U    00/U    01/U    12/T    21/U    11/U
LVM 046/086 047/084 047/086 051/089 053/089 053/089 054/091
    10/N    00/U    00/U    01/B    12/T    22/T    22/T
HDN 055/088 055/084 055/085 057/091 058/091 059/091 059/093
    10/U    00/U    00/U    01/U    12/T    21/U    11/U
MLS 058/087 057/082 056/083 059/088 060/089 061/090 061/091
    20/U    00/N    00/U    00/U    11/U    11/U    11/U
4BQ 057/087 056/083 054/082 056/088 059/088 059/089 059/090
    20/U    00/U    00/U    00/U    11/B    11/U    11/U
BHK 054/085 052/079 051/079 052/084 055/085 056/086 056/087
    30/U    00/N    00/U    00/U    11/U    11/U    11/U
SHR 052/088 051/083 051/083 053/088 055/087 054/087 055/088
    10/U    00/U    00/U    01/U    22/T    22/T    21/B

&&

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

&&

$$
WEATHER.GOV/BILLINGS



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