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161
FXUS65 KBYZ 230855
AFDBYZ

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BILLINGS MT
255 AM MDT THU OCT 23 2014

.SHORT TERM...VALID FOR TDY AND FRI...

130 KT JET MOVING IN OFF THE PACIFIC WILL MOVE THROUGH THE REGION
LATE TODAY THROUGH FRI. THE BULK OF THE JET DIVERGENCE WILL REMAIN
N OF THE AREA AS MODELS ALL KEEP THE JET CORE TO THE N.
WEAK UPPER RIDGING EARLY THIS MORNING WILL GIVE WAY TO FAST SW
FLOW THROUGH THIS EVENING. PIECES OF VORTICITY WILL MOVE THROUGH
THE AREA WITH SOME Q-VECTOR CONVERGENCE. FLOW WILL THEN BECOME
ZONAL LATE TONIGHT THROUGH FRI...AND UPPER RIDGING WILL RETURN TO
THE AREA FRI NIGHT.

PLAN VIEW OF MOISTURE SHOWED SOME APPROACHING THE WESTERN ZONES
BY 00Z FRI. TIME-HEIGHT CROSS SECTIONS KEPT THE LOWER LEVELS DRY
SO THERE WILL BE QUITE A BIT OF CLOUD COVER BUT NO PRECIPITATION
TODAY. LEE TROUGHING THIS MORNING WILL GIVE WAY TO PRE-FRONTAL
MIXING...AND BREEZY CONDITIONS ARE EXPECTED OVER THE CENTRAL AND
WESTERN ZONES. TEMPERATURES WERE IN GOOD SHAPE TODAY...IN THE
UPPER 60S TO LOWER 70S...GIVEN THE COMBINATION OF GOOD MIXING AND
CLOUD COVER.

PACIFIC COLD FRONT WILL CROSS THE AREA TONIGHT WITH SOME
FRONTOGENESIS. MOISTURE PROFILES SUGGESTED THAT SCATTERED SHOWERS
ARE POSSIBLE OVER THE WESTERN MOUNTAINS AND KLVM AREA AFTER 06Z.
PACIFIC MOISTURE WILL CONTINUE STREAMING INTO THE W ON FRI THROUGH
FRI NIGHT BRINGING A CHANCE OF MAINLY MOUNTAIN SHOWERS. FRI WILL
HAVE LESS WIND THAN TODAY WITH A WEAKER PRESSURE GRADIENT OVER THE
AREA. A COOLER DAY IS EXPECTED ON FRI BEHIND THE THU NIGHT COLD
FRONT. TEMPERATURES WILL STILL BE ABOVE NORMAL IN THE 60S. ARTHUR

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

THE EXTENDED PERIOD WILL BEGIN WITH A DRY AND MILD SATURDAY...
COURTESY OF UPPER LEVEL RIDGING AHEAD OF PAC COAST TROF. A PATTERN
SHIFT TO A MORE PROGRESSIVE PACIFIC FLOW...AND THUS COOLER
TEMPS...WILL BEGIN SUNDAY. TIMING OF THE INITIAL WAVE AND COLD
FRONT CONTINUES TO TREND A BIT SLOWER SO HAVE RAISED EXPECTED
HIGHS ON SUNDAY AND PUSHED POPS BACK SLIGHTLY. BEST CHANCE OF PCPN
W/ THIS INITIAL SHORTWAVE LOOKS TO BE SUNDAY NIGHT AS THE GFS/EC
EACH HIT OUR SOUTH PARTS WITH GREATEST QPF PER MID LEVEL
FRONTOGENESIS AND AT LEAST BRIEFLY VEERED N-NW UPSLOPE SFC WINDS.
HAVE RAISED POPS IN THIS AREA SUNDAY NIGHT AND HAVE GIVEN OUR
SOUTHERN MTNS A COUPLE INCHES OF SNOWFALL. SHOULD BE ANOTHER WEAK
SHORTWAVE ON MONDAY SO HAVE SUSTAINED ISOLD TO SCT POPS HERE...
ESPECIALLY GIVEN THE CYCLONIC FLOW/COLDER AIR ALOFT ASSOCIATED
WITH TROF. CONSENSUS CONTINUES TO SUGGEST BRIEF RIDGING FOR
TUESDAY. HIGH TEMPS SHOULD COOL TO THE 50S FOR HIGHS MONDAY/
TUESDAY...ABOUT NORMAL FOR LATE OCTOBER. ITS WORTH NOTING THAT
BILLINGS HAS NOT SEEN A COOLER THAN NORMAL DAY SINCE OCTOBER 3RD.

MODELS BEGIN TO DIVERGE QUITE A BIT BY THE MIDDLE OF NEXT WEEK
WITH A GREAT AMOUNT OF SPREAD INVOLVING THE FLOW IN THE NORTHEAST
PACIFIC. THIS MODEL UNCERTAINTY MAKES SENSE GIVEN THE INVOLVEMENT
OF TROPICAL STORM ANA NORTHWEST OF HAWAII. SO AM EXPECTING LOW
CONFIDENCE IN THE FAR EXTENDED PERIOD TO CONTINUE AS WE EASE
OURSELF INTO A PATTERN SHIFT OVER THE COMING DAYS. IN ANY
EVENT...WILL SUSTAIN NEAR CLIMO POPS AND TEMPS FOR NEXT WEDNESDAY
AS BOTH THE GFS AND EC EACH SHOW SOME WEAK ENERGY BY THEN...THOUGH
IN DIFFERING REGIMES. BY 168 HOURS THESE MODELS ARE COMPLETELY OUT
OF PHASE WITH EACH OTHER WITH THE FLOW OVER THE WESTERN CONUS AND
EASTERN PACIFIC.

JKL
&&

.AVIATION...

VFR WILL PREVAIL ACROSS THE AREA TODAY AND TONIGHT...WITH
INCREASED MID AND HIGH CLOUD FROM THE WEST. IT WILL BE WINDY ALONG
THE FOOTHILLS WITH GUSTS OF 35-45 KTS AT KLVM.

&&

.PRELIMINARY POINT TEMP/POPS...

    TDY FRI     SAT     SUN     MON     TUE     WED
-------------------------------------------------------
BIL 071 047/064 041/069 045/061 037/054 031/056 037/058
    0/B 00/B    10/U    02/W    32/W    11/B    12/W
LVM 069 045/062 040/069 043/055 032/048 028/054 034/054
    0/N 22/W    20/U    13/W    32/W    11/B    22/W
HDN 073 042/068 037/072 039/063 035/054 028/058 033/060
    0/B 00/B    10/U    02/W    32/W    11/B    12/W
MLS 073 043/067 039/070 042/064 038/052 029/056 032/056
    0/U 00/B    10/U    02/W    22/W    11/B    12/W
4BQ 072 042/068 038/070 043/067 037/052 028/055 032/058
    0/U 00/B    10/U    02/W    42/W    11/U    12/W
BHK 070 041/066 034/065 039/065 037/050 026/050 029/054
    0/U 00/B    10/U    02/W    22/W    11/B    12/W
SHR 071 041/067 034/073 039/066 033/052 025/057 028/060
    0/B 00/B    10/U    02/W    42/W    11/B    12/W

&&

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

&&

$$
WEATHER.GOV/BILLINGS




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