National Weather Service National Headquarters

• Home
• Site Map
• News
• Organization
• Search for: NWS All NOAA 

000
FXUS65 KBYZ 190259
AFDBYZ

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BILLINGS MT
859 PM MDT TUE JUN 18 2013

.UPDATE...
UPDATE TO FORECAST THIS EVENING. UPPER RIDGE OF HIGH PRESSURE
MOVING SLOWLY EASTWARD ACROSS THE FORECAST AREA THIS EVENING AS AN
UPPER TROUGH OF LOW PRESSURE MOVES ON TO THE PACIFIC WEST COAST.
ISOLATED THUNDERSTORMS DID DEVELOP OVER THE HIGHER TERRAIN THIS
AFTERNOON AND EVENING BUT DID NOT MOVE VERY FAR AWAY FROM THE
MOUNTAINS DUE TO VERY LIGHT MID-LEVEL STEERING WINDS. A FEW STORMS
DID PRODUCE HEAVY RAINFALL AS THEY WERE ABLE TO TAP INTO A SHALLOW
MOIST BOUNDARY LAYER. BULK WIND SHEAR WAS NON-EXISTENT AND NO
SEVRE WEATHER DEVELOPED. FOR TONIGHT...HAVE LOWERED POPS TO
ISOLATED FOR THE REST OF THE EVENING WITH A DRY FORECAST AFTER
06Z. DID BUMP OVERNIGHT LOWS UP A FEW DEGREES ACROSS THE CENTRAL
ZONES AS THERMAL RIDGE WILL REMAIN OVER THESE AREAS TONIGHT. REST
OF THE FORECAST ON TRACK. RICHMOND

&&

.SHORT TERM...VALID FOR WED AND THU...

CONVECTION WAS OCCURRING OVER SOUTHERN PARTS OF THE AREA PER
RADAR IMAGERY THIS AFTERNOON. LATEST RAP ANALYSIS SHOWED SURFACE
CAPES OF 1500-2500 J/KG OVER SE MT. ELSEWHERE...CAPES WERE IN THE
700 TO 2000 J/KG RANGE...PRETTY VARIABLE ACROSS THE FORECAST AREA.
SHEAR WAS GENERALLY WEAK...HOWEVER VALUES WERE 30 TO 35 KT OVER SE
MT...SO BEST CHANCES OF ANY STRONG TO SEVERE STORMS WILL BE OVER
THE SE. WILL CONTINUE TO MENTION SMALL HAIL/GUSTY WINDS ACROSS THE
AREA DUE TO THE CAPES AND INVERTED-V SOUNDINGS. HAD POPS ACROSS
THE AREA THIS EVENING...THEN ACTIVITY SHOULD DISSIPATE AFTER
MIDNIGHT MDT WITH LOSS OF HEATING.

JET ENERGY WILL ROTATE AROUND THE UPPER LOW OVER THE PACIFIC
NW...CAUSING IT TO PROGRESS E WITH TIME. WILL HAVE INCREASING
Q-VECTOR CONVERGENCE OVER THE AREA STARTING ON WED...AS SHORTWAVES
CONTINUE MOVING INTO THE REGION. UPPER DIFLUENCE WILL CONTINUE TO
CONTRIBUTE TO LIFT ON WED. BOTH THE GFS AND WRF HAD LARGE CAPES
2000-3000 J/KG OVER THE FAR EASTERN AND NORTHERN PARTS OF THE
AREA WED AND WED EVENING...AS WELL AS INCREASING SHEAR OVER THE
AREA FROM W TO E. HOWEVER...DRY AIR OVER THE FOUR CORNERS REGION
THIS AFTERNOON WILL ADVECT N INTO THE FORECAST AREA ON
WED...KEEPING THE E DRY THROUGH THE DAY. WILL KEEP A CHANCE OF
THUNDERSTORMS OVER THE NW HALF OF THE REGION FROM KBIL N AND W...AND
WILL CONTINUE TO MENTION POSSIBLE SEVERE OVER THE N. COLD FRONT
MOVES THROUGH WED NIGHT BRINGING A CHANCE OF THUNDERSTORMS TO MOST
OF THE AREA.

UPPER LOW WILL ROTATE OVER ID THU AND THU NIGHT. CAPES WILL BE VERY
LOW ON THU. HAD LOW POPS ACROSS THE AREA. A SECONDARY COLD FRONT
WITH FRONTOGENESIS WILL MOVE THROUGH THE REGION THU
NIGHT...BRINGING A BETTER CHANCE OF PRECIPITATION.

WILL HAVE A WARM NIGHT TONIGHT AS 850 MB THERMAL RIDGE MOVES INTO
THE AREA AND LOW-LEVEL JET STRENGTHENS OVER THE E. WED WILL BE HOT
WITH 700 MB TEMPERATURES AROUND +14 DEGREES C AHEAD OF THE COLD
FRONT. ARTHUR


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

PAC NW UPPER LOW WILL KICK SLOWLY THROUGH THE REGION FRI/SAT...AND
ALL MODELS HAVE TRENDED SIMILARLY WITH REGARD TO STRENGTH AND
TIMING OF THIS FEATURE. WITH CONFIDENCE HAVE RAISED POPS ACROSS
THE REGION ON THESE DAYS. ACTIVITY IN THE WEST SHOULD BE NON-
SEVERE THOUGH WITH LOW WET BULB TEMPS SOME SMALL HAIL IS POSSIBLE
WITH ANY STRONGER CELLS. GFS SHOWS DEEPER MOISTURE AND INSTABILITY
MAY SURGE FROM THE DAKOTAS INTO OUR EAST AHEAD OF THE UPPER
LOW...SO CANNOT RULE OUT THE POTENTIAL FOR SEVERE STORMS IN OUR
EAST ON THESE DAYS...ALONG WITH HEAVY RAIN. SYSTEM WILL EXIT TO
OUR EAST EITHER SATURDAY NIGHT OR EARLY SUNDAY. TEMPS FRIDAY AND
SATURDAY WILL COOL TO SLIGHTLY BELOW NORMAL.

DRIER CONDITIONS SHOULD EMERGE BY SUNDAY IN OUR WEST...WITH A
PERIOD OF DRY WX PERHAPS EXTENDING INTO MONDAY UNDER SHORTWAVE
RIDGING. MODELS DIVERGE A BIT IN THE HANDLING OF THE PACIFIC FLOW
HERE. WILL ADVERTISE A DRY PERIOD SUNDAY INTO MONDAY...THEN SLIGHT
POPS MONDAY AFTERNOON THROUGH TUESDAY AS WE MAY BE IMPACTED BY
PACIFIC SHORTWAVE ENERGY BY THEN. TEMPS SHOULD RETURN BACK TO A
LITTLE ABOVE NORMAL BY DAYS 6/7.

LOOKING FURTHER AHEAD...LATEST GFS/ECMWF SHOW STRONGER RIDGING
WITH NEAR 590DAM HEIGHTS BY WED/THU OF NEXT WEEK. WILL NEED TO
KEEP WATCH OF THIS TREND.

JKL


&&

.AVIATION...

AN ISOLATED THUNDERSTORM MAY PERSIST UNTIL 06Z FROM NORTHERN
WYOMING INTO SOUTHEAST MONTANA WITH LOCAL MVFR VISIBILITY IN HEAVY
RAINFALL. OTHERWISE VFR CONDITIONS EXPECTED THROUGH MID DAY
WEDNESDAY. ANOTHER ROUND OF ISOLATED TO SCATTERED THUNDERSTORMS IS
EXPECTED WEDNESDAY AFTERNOON AND EVENING. WIND GUSTS WITH THESE
STORMS WILL BE STRONG AT TIMES. CHAMBERS
&&

.PRELIMINARY POINT TEMP/POPS...

    WED     THU     FRI     SAT     SUN     MON     TUE
-----------------------------------------------------------
BIL 061/089 052/077 052/072 052/069 051/078 054/082 056/082
    22/T    22/T    33/T    34/T    41/B    12/T    22/T
LVM 051/084 043/072 041/069 042/067 046/079 046/082 049/081
    33/T    23/T    33/T    34/T    40/B    02/T    22/T
HDN 061/091 053/078 052/074 050/072 050/078 052/082 052/083
    21/U    22/T    32/T    34/T    41/B    12/T    22/T
MLS 061/096 058/081 055/076 056/076 055/080 056/083 057/083
    21/N    22/T    44/T    34/T    43/T    22/T    22/T
4BQ 061/095 054/081 055/076 054/075 053/079 054/084 055/084
    21/N    22/T    44/T    34/T    42/T    12/T    22/T
BHK 057/090 057/080 054/076 055/074 054/076 054/080 057/082
    21/N    22/T    36/T    54/T    43/T    22/T    22/T
SHR 054/090 048/078 050/073 048/073 047/076 049/081 050/082
    31/U    22/T    32/T    23/T    31/B    12/T    22/T

&&

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

&&

$$
WEATHER.GOV/BILLINGS