Area Forecast Discussion
Issued by NWS Billings, MT

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000
FXUS65 KBYZ 160927
AFDBYZ

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BILLINGS MT
327 AM MDT SAT AUG 16 2014

.SHORT TERM...VALID FOR TDY AND SUN...

UPPER LOW OVER NORTHERN IDAHO THIS MORNING WILL SHIFT ACROSS
NORTHERN MONTANA TODAY. STRONGEST UPPER DIVERGENCE WILL MOVE INTO
NORTHEAST MONTANA AND NORTHWEST NORTH DAKOTA. SHORTWAVE ENERGY
WILL SLIDE ACROSS MAINLY THE NORTHERN HALF OF THE FORECAST AREA
FOR ASCENT. A SURFACE TROUGH CURRENTLY POSITIONED FROM TREASURE
COUNTY INTO EASTERN BIG HORN COUNTY WILL SLIDE EAST AND TAKE THE
HIGHER PRECIPITABLE WATERS WITH IT. THE TROUGH GETS INTO FAR
EASTERN MONTANA THIS AFTERNOON. ALONG AND EAST OF THE THIS TROUGH
CAPES RISE TO NEAR 1000 J/KG WITH PRECIPITABLE WATERS AROUND AN
INCH. SHEAR INCREASES THROUGH THE DAY...BUT THE STRONGEST SHEAR
REMAINS BACK OVER SOUTH CENTRAL MONTANA. WOULD EXPECT A FEW STRONG
STORMS OVER CUSTER/FALLON/CARTER COUNTIES THIS AFTERNOON AND
EVENING. WILL HOLD OFF ON SEVERE WORDING AS SREF PROGS KEEP THE
HIGHEST RISK OF SEVERE OVER NORTHEAST MONTANA AND WESTERN NORTH
DAKOTA. WILL ISSUE AN HWO FOR THE POTENTIAL OF STRONG STORMS AND
GET THE FOOT IN THE DOOR FOR POSSIBLE UPGRADES TO SEVERE POTENTIAL
AS THE DAY DEVELOPS.

CENTRAL AND WESTERN ZONES WILL BE ON THE WEST SIDE OF THE TROUGH
IN THE DRIER AIR...AND THUS HAVE LIMITED CAPES. WILL KEEP MENTION
OF ISOLATED STORMS AS ENERGY DOES STREAM AROUND THE UPPER LOW TO
THE NORTH. ACTIVITY WILL NOT HAVE THE HIGH PWATS TO WORK WITH SO
DO NOT EXPECT ACTIVITY TO BE QUITE AS WET OR STRONG AS THE STORMS
OF FRIDAY. TEMPERATURES WILL BE SEASONAL TODAY AND MOST LIKELY
JUST A BIT COOLER WITH SLIGHTLY COOLER READINGS AT 700MB.

THE UPPER LOW DROPS SOUTHEAST THROUGH NORTH DAKOTA ON SUNDAY. PVA
STREAMS ACROSS EASTERN MONTANA. RAISED POPS A LITTLE MORE OVER THE
SOUTHEAST WITH STRONG ASCENT DRIFTING ACROSS. HIGHEST CAPES STAY
OVER THE DAKOTAS BUT PWATS REMAIN ABOVE .75 INCHES...SO EXPECT
SOME STORMS TO CONTAIN BRIEF HEAVY RAINFALL BUT AM NOT
ANTICIPATING SEVERE WEATHER. LOOKS LIKE THE RISK OF SEVERE WEATHER
WILL REMAIN EAST OF THE STATE LINE IN VICINITY OF THE SURFACE
TROUGH. NORTHWEST WINDS WILL KICK UP A BIT SUNDAY AFTERNOON WITH A
SURFACE LOW DEEPENING OVER NORTH DAKOTA...SO SHOULD BE A LITTLE
BREEZY. HIGH TEMPERATURES SHOULD BE SIMILAR TO SATURDAY. TWH

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

NO LARGE CHANGES IN THE EXTENDED FORECAST WITH THIS UPDATE. THE
MAIN THEME REMAINS A PERIOD OF SEASONABLE AND DRIER CONDITIONS
FOLLOWED BY A TROUGH BUILDING IN BY MID TO LATE WEEK BRINGING
SLIGHTLY COOLER AND WETTER CONDITIONS. FORECAST CONFIDENCE IN THE
MAGNITUDE OF THE TROUGH IS SLIGHTLY LOWER TODAY THAN YESTERDAY.

RISING HEIGHTS AND SHORTWAVE RIDGING ON MONDAY WILL RESULT IN A
SEASONABLE AND DRY DAY FOR THE FORECAST AREA. 700 MB MIX DOWN
TEMPERATURES SUPPORT FORECAST HIGH TEMPERATURES IN THE MID TO
UPPER 80S. THE FLOW ALOFT BECOMES INCREASINGLY SOUTHWESTERLY BY
TUESDAY INTO WEDNESDAY AS A PACIFIC TROUGH APPROACHES THE REGION.
THIS WILL ALLOW FOR ADVECTION OF SOME +12C 700 MB TEMPERATURES
INTO THE FORECAST AREA...WHICH WILL HELP HIGH TEMPERATURES BACK
INTO THE LOW 90S ON TUESDAY. SOME INCREASING MOISTURE IN THE
SOUTHWESTERLY FLOW WILL ALLOW FOR A SLIGHT CHANCE OF POPS ACROSS
THE PLAINS BY TUESDAY AND WEDNESDAY.

THE MODELS ARE STRUGGLING WITH THEIR DEPICTION OF THE PACIFIC
TROUGH. THE GFS REMAINS THE MOST ROBUST WITH THE UPPER-LEVEL
LOW...WANTING TO CUT OFF A LOW OVER OREGON / IDAHO INTO THE
SATURDAY. THE EC REMAINS MORE PROGRESSIVE WITH THE WAVE...SLOWLY
DRIFTING IT ACROSS THE FORECAST AREA INTO SATURDAY. ONE OF THE
MAIN PROBLEMS SEEMS TO BE IN HOW THE MODELS ARE HANDLING THE
CALIFORNIA LOW...AND WHETHER ITS PLACEMENT CREATES ENOUGH WEAKNESS
IN THE FLOW TO ALLOW THE NORTHERN WAVE TO DIG FARTHER SOUTH.
ANOTHER INTERESTING WRINKLE WITH THESE MODEL RUNS IS HOW THEY
HANDLE A TROPICAL SYSTEM MOVING NORTHWARD TOWARD THE CALIFORNIA
LOW. WHILE IT IS UNCLEAR HOW THAT WOULD EXACTLY IMPACT THE
OVERALL PATTERN...THERE ARE ENOUGH PIECES TO THE PUZZLE THAT
SUBTLE CHANGES IN THESE COMPLEX INTERACTIONS WILL RESULT IN
WIDELY VARYING MODEL SOLUTIONS. THE ONLY THING THAT REMAINS CLEAR
IS THAT THERE WILL BE A TROUGH AROUND IN THE THURSDAY THROUGH
SATURDAY PERIOD TO BRING A LITTLE RELIEF FROM THE HEAT AND A
BETTER CHANCE AT SOME SHOWERS AND THUNDERSTORMS. CHURCH

&&

.AVIATION...

A BATCH OF SHOWERS AND ISOLATED THUNDERSTORM ACTIVITY WILL
CONTINUE ALONG AND NORTH OF A LINE FROM KLVM TO KBIL TO KMLS
THROUGH THE MORNING. LOCALIZED MVFR CONDITIONS ARE POSSIBLE IN THE
HEAVIER CELLS. THAT BATCH SHOULD MOVE OFF TOWARD KGDV BY THE
AFTERNOON...BUT MORE ISOLATED / SCATTERED SHOWER AND THUNDERSTORM
DEVELOPMENT IS POSSIBLE ALONG THIS LINE BY THE AFTERNOON.
OTHERWISE...VFR CONDITIONS ARE EXPECTED TO PREVAIL AT ALL TAF
SITES. CHURCH

&&

.PRELIMINARY POINT TEMP/POPS...

    TDY SUN     MON     TUE     WED     THU     FRI
-------------------------------------------------------
BIL 087 061/088 060/087 061/091 062/089 060/084 060/079
    2/T 22/T    21/B    12/T    22/T    23/T    33/T
LVM 084 052/088 052/088 052/090 052/086 052/079 050/076
    2/T 21/B    11/U    12/T    22/T    23/T    33/T
HDN 089 058/090 058/089 057/093 058/091 056/088 056/083
    2/T 22/T    21/B    12/T    22/T    23/T    33/T
MLS 089 061/088 061/087 061/091 062/091 060/086 060/083
    4/T 33/T    21/B    12/T    22/T    23/T    33/T
4BQ 089 060/088 060/086 059/091 061/092 059/088 059/084
    3/T 23/T    31/B    11/B    22/T    22/T    23/T
BHK 087 057/086 058/084 055/088 057/089 055/085 055/081
    5/T 44/T    31/B    11/B    22/T    22/T    33/T
SHR 086 054/088 054/086 054/090 056/089 054/086 053/080
    2/T 21/B    11/U    12/T    22/T    22/T    23/T

&&

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

&&

$$
WEATHER.GOV/BILLINGS



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