Area Forecast Discussion
Issued by NWS Billings, MT

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000
FXUS65 KBYZ 111521
AFDBYZ

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BILLINGS MT
921 AM MDT FRI JUL 11 2014

.UPDATE...
MADE SOME CHANGES TO THE FORECAST TODAY TO INCREASE CLOUDS AND
WINDS ACROSS THE AREA. EAST WINDS HAVE INCREASED ACROSS THE AREA
THIS MORNING IN THE WAKE OF A COOL FRONT. VAD WINDS INDICATING
UPSLOPE FLOW TO AROUND 7000 FEET WHICH IS ADVECTING LOW LEVEL
MOISTURE INTO THE AREA. THIS HAS PRODUCED A LOW STRATUS CLOUD DECK
OVER CENTRAL MONTANA...INCLUDING BILLINGS. UPSLOPE FLOW WILL
DIMINISH BY NOON AND LOW CLOUD DECK WILL BEGIN DISSIPATING. STILL
ANTICIPATE HIGH TEMPERATURES IN THE MID TO UPPER 80S THIS
AFTERNOON WITH 850 MB TEMPERATURES OF +24C. RICHMOND

&&

.SHORT TERM...VALID FOR TDY AND SAT...

WE HAVE TRENDED THE FORECAST TOWARD A BIT WARMER AND DRIER IDEA IN
THE SHORT TERM PERIOD THROUGH SAT...AND ALSO DOWNPLAYED THE SEVERE
THUNDERSTORM RISK THIS AFTERNOON AND EVENING A BIT.

TODAY...CONVECTION MOVING THROUGH NORTHEASTERN MT AS OF 09 UTC MAY
SKIRT THE BAKER AREA EARLY THIS MORNING...BUT OTHERWISE WE WILL BE
WAITING FOR DIURNAL HEATING AND LOW-LEVEL UPSLOPE /EASTERLY/ WINDS
TO BRING A CHANCE OF STORMS TO SOME OTHER AREAS BY THIS AFTERNOON.
THE 00 UTC MODELS CONTINUED TO PROVIDE LITTLE EVIDENCE FOR DEFINED
SYNOPTIC-SCALE FORCING TO AIDE STORMS THIS AFTERNOON THOUGH...WITH
WEAK HEIGHT RISES EVEN APPARENT AT 500 MB. THAT SCENARIO IS SELDOM
SUPPORTIVE OF MORE THAN ISOLATED STORMS. CONVECTION-ALLOWING MODEL
GUIDANCE LIKE THAT MAKING UP THE 00 UTC SPC SSEO ISN/T GENEROUS IN
SIMULATING STORMS TOO FAR AWAY FROM THE HIGHER TERRAIN EITHER SAVE
FOR IN CARTER COUNTY BETWEEN 21 AND 00 UTC. WE THUS CHOSE TO /1 GO
WITH A DRY FORECAST THIS AFTERNOON FROM BILLINGS AND ROUNDUP EAST-
WARD TO MILES CITY AND BAKER...AND 2/ REMOVE THE MENTION OF SEVERE
STORMS FROM THE EXPLICIT FORECAST /POINT-AND-CLICK AND NDFD SET OF
PRODUCTS/ ALTOGETHER FOR THE WHOLE AREA. WE STILL BELIEVE ISOLATED
SEVERE STORMS WITH LARGE HAIL OR DAMAGING WINDS ARE POSSIBLE...BUT
EXPECTED COVERAGE IS NOT ENOUGH TO PORTRAY THIS AS A BIG EVENT. IT
LOOKS LIKE A NARROW CORRIDOR WITH OVERLAPPING 0-6-KM BULK SHEAR OF
40 KT AND MLCAPE OF 500-1000 J/KG WILL EXIST FROM NEAR LODGE GRASS
EAST TO BROADUS AND INTO CARTER COUNTY THIS AFTERNOON...WHICH DOES
MEAN THE CONDITIONAL PROBABILITY OF A SEVERE STORM IS GREATEST FOR
THAT AREA. AGAIN THOUGH...IT/S VERY CONDITIONAL ON STORMS FORMING.
OTHERWISE...MIXING TO 700 MB SUPPORTS HIGHS WELL INTO THE 80S F IN
MOST AREAS TODAY AND PROBABLY NEAR 90 F IN SOME SPOTS.

TONIGHT...WE HAVE SOME CHANCE OF STORMS IN PLAY DURING THE EVENING
FOR MOST OF SOUTHERN MT AND NORTH CENTRAL WY...BUT AGAIN WITH WEAK
HEIGHT RISES ALOFT THE COVERAGE OF STORMS MAY BE KEPT IN CHECK. IT
LOOKS LIKE A BETTER CHANCE FOR STORMS COULD ACTUALLY ARRIVE ACROSS
SOUTHEASTERN MT AFTER 06 UTC AS HEIGHTS ALOFT START TO FALL. THERE
IS SOME RISK OF ISOLATED SEVERE HAIL IF THAT OCCURS WITH EFFECTIVE
SHEAR OF 45+ KT AND MUCAPE NEAR 1000 J/KG IN PLACES LIKE BAKER.

SAT...NORTHWEST FLOW ALOFT WILL BE IN PLACE AND FORECAST SOUNDINGS
SUGGEST A DISTINCT MID-LEVEL SUBSIDENCE INVERSION AND MARGINAL /IF
ANY/ INSTABILITY OVER MUCH OF THE PLAINS DURING THE DAY. THEREFORE
WE DECIDED TO RESTRICT THE STORM CHANCES SAT AFTERNOON AND EVENING
TO LOCATIONS IN AND AROUND THE HIGHER TERRAIN FROM LIVINGSTON OVER
TO BRIDGER AND SHERIDAN. HIGHS WILL AGAIN BE IN THE 80S F. SCHULTZ

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

MODELS WERE IN VERY GOOD AGREEMENT THROUGH WEDNESDAY WITH
DIVERGENCE STARTING ON THURSDAY. VERY COOL PATTERN FOR JULY
SETTING UP FOR MONDAY WITH A MODERATION IN TEMPERATURES BEGINNING
ON THURSDAY. NORTHWEST FLOW FOR MONDAY WITH A VERY DEEP AND
ANOMALOUS UPPER LOW PROGGED OVER WISCONSIN. THIS WILL SEND MUCH
COOLER TEMPERATURES INTO THE AREA ON MONDAY WITH 850MB READINGS AS
COOL AS 10C INVADING FAR EASTERN MONTANA. HIGHS WILL BE HELD TO
AROUND 80 DEGREES AND POSSIBLY AS COOL AS THE UPPER 70S. UPSLOPE
FLOW WILL ALLOW FOR COME CLOUD COVER...BUT ATMOSPHERE NOT PROGGED
TO BE THAT MOIST THEN...SO HELD OFF ON PRECIPITATION.

BROUGHT IN SHOWERS MONDAY EVENING AS ENERGY ROTATES AROUND AN
UPPER RIDGE TO THE WEST AND SWINGS ACROSS THE FORECAST AREA. WILL
KEEP POPS IN TUESDAY AND WEDNESDAY WITH NORTHWEST FLOW. HEIGHTS
RISE GRADUALLY THROUGH WEDNESDAY...SO TEMPERATURES SHOULD WARM
INTO MID WEEK. 90S SHOULD RETURN BY FRIDAY AS AN UPPER RIDGE NOSES
BACK INTO THE REGION. WILL KEEP PRECIPITATION OUT ON THURSDAY WITH
THE RIDGE IN PLACE. THE RIDGE BREAKS DOWN SOMEWHAT ON FRIDAY AND
ALLOWS ENERGY TO SCOOT ACROSS THE NORTHWEST QUARTER OF THE
FORECAST AREA...SO ADDED POPS FOR THOSE LOCATIONS. TWH
&&

.AVIATION...

SHOWERS AND THUNDERSTORMS CONTINUE TO IMPACT EASTERN MONTANA THIS
MORNING...MAINLY EAST AND NORTH OF KMLS. BRIEF LOCALIZED MVFR TO
IFR CONDITIONS ARE POSSIBLE WITH LOCALLY HEAVY RAINFALL.

A STRATUS DECK HAS DEVELOPED BRINGING MVFR CIGS TO AREAS FROM
KBIL TO THE NORTH AND WEST...INCLUDING ROUNDUP...HARLOWTON...AND
LEWISTOWN. OTHERWISE VFR CONDITIONS WILL PREVAIL ACROSS THE
REGION.

A FEW THUNDESTORMS ARE EXPECTED SOUTH OF BILLINGS THIS
AFTERNOON...INCLUDING SOUTHERN MOST PORTION OF MONTANA AND
NORTHERN WYOMING. A FEW STORMS MAY BE STRONG...ESPECIALLY FROM
BROADUS TO EKALAKA WITH HAIL AND TORRENTIAL RAINFALL.
THUNDERSTORMS ARE EXPECTED TO BECOME MORE NUMEROUS THIS EVENING
BUT STILL BE MAINLY SCATTERED IN NATURE...WITH BEST POTENTIAL
ALONG EASTERN MOUNTAINS SLOPES AND FROM SHERIDAN TO EKALAKA. LOCALLY
HEAVY RAIN WITH STORMS MAY RESULT IN BRIEF MVFR TO IFR
CONDITIONS. AAG

&&

.PRELIMINARY POINT TEMP/POPS...

    TDY SAT     SUN     MON     TUE     WED     THU
-------------------------------------------------------
BIL 088 062/088 061/086 058/080 058/083 056/086 058/091
    1/B 21/B    11/U    11/U    22/T    22/T    21/U
LVM 086 052/087 052/085 051/081 050/081 050/084 050/089
    3/T 33/T    31/U    12/T    23/T    33/T    22/T
HDN 089 059/088 060/088 058/081 056/084 056/087 058/092
    1/B 21/B    11/U    11/U    21/B    12/T    21/U
MLS 090 063/087 061/084 057/077 056/082 056/085 059/091
    1/B 21/U    11/U    11/U    11/U    11/U    11/U
4BQ 090 059/086 060/087 056/077 056/080 055/083 057/089
    3/T 31/B    11/U    11/U    21/U    12/T    21/U
BHK 086 059/084 056/080 053/071 050/076 052/080 055/087
    1/B 42/T    11/U    11/U    11/U    11/U    11/U
SHR 086 056/084 055/086 055/078 052/080 051/081 053/087
    3/T 32/T    22/T    22/T    22/T    22/T    22/T

&&

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

&&

$$
WEATHER.GOV/BILLINGS


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