Area Forecast Discussion
Issued by NWS Billings, MT

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FXUS65 KBYZ 240326
AFDBYZ

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE BILLINGS MT
826 PM MST SUN NOV 23 2014

.UPDATE...

TRENDS IN THE GRIDS LOOK GOOD...SO NO UPDATE NEEDED. REIMER

&&

.SHORT TERM...VALID FOR MON AND MON NIGHT...

NORTHWEST FLOW ALOFT WILL BE OVER THE FORECAST AREA THROUGH
MONDAY NIGHT. THIS NORTHWEST FLOW WILL ALLOW SEVERAL DISTURBANCES
TO FLOAT THROUGH THE AREA THE NEXT 24 HOURS. THE FIRST DISTURBANCE
WAS WORKING INTO EASTERN MONTANA AT THE MOMENT. A FEW LIGHT RAIN
AND SNOW SHOWERS WERE PRESENT WITH THIS ENERGY. ANOTHER STRONGER
WAVE WILL CRUISE INTO THE AREA LATE TONIGHT AND EARLY MONDAY. WILL
KEEP POPS GOING FOR MOST LOCATIONS FOR BOTH OF THESE WAVES...BUT
THE HIGHEST PROBABILITY OF GETTING PRECIPITATON WILL BE OVER THE
EAST AND OVER THE MOUNTAINS.

A STRONGER WAVE WILL DROP INTO NORTHEAST MONTANA MONDAY NIGHT.
THIS ENERGY WILL CARRY WITH IT THE LEFT FRONT QUAD OF A JET MAX
FOR ASCENT. RAISED POPS OVER THE EAST FOR LATE MONDAY NIGHT.
ALSO...A SURFACE LOW WILL STRENGTHEN AND DROP INTO SOUTH CENTRAL
CANADA MONDAY NIGHT AND CREATE A TIGHT SURFACE PRESSURE GRADIENT
OVER THE WEST. ORIENTATION OF THE GRADIENT SHOULD BE PERFECT FOR
STRONG WINDS AND LOCAL STUDIES INDICATED THAT A STRONG ADVISORY
EVENT WILL OCCUR FOR LIVINGSTON AND NYE. WILL ISSUE A WIND
ADVISORY FOR MONDAY NIGHT THROUGH TUESDAY MORNING. TWH

.LONG TERM...VALID FOR TUE...WED...THU...FRI...SAT...SUN...

CONFIDENCE IN ACCUMULATING SNOWFALL TUESDAY NIGHT AND WEDNESDAY IS
INCREASING SUCH THAT WE BELIEVE A FEW INCHES WILL FALL DURING THAT
TIME FRAME...ESPECIALLY OVER PARTS OF SOUTH CENTRAL MT. WE ARE NOT
CALLING FOR NEARLY AS MUCH SNOW AS THE QPF FROM THE 12 UTC GFS AND
00 UTC ECMWF SOLUTIONS WOULD SUPPORT THOUGH BECAUSE THE DEEP-LAYER
VERTICAL MOTION FIELD LEAVES A LOT TO BE DESIRED. SNOW WILL LIKELY
BE DRIVEN BY NOTEWORTHY FRONTOGENESIS WITH MOISTURE ADVECTION ATOP
THE FRONTAL ZONE...BUT QG-FORCING ALOFT IS LACKING AND THAT LEAVES
A SHORT AGEOSTROPHIC CIRCULATION THROUGH THE FRONTAL ZONE. WE LIKE
TO SEE A MUCH DEEPER CIRCULATION FOR INTENSE MESOSCALE SNOW BANDS.
MOREOVER...SNOW-TO-LIQUID RATIOS WILL BE BETWEEN 10 AND 13 TO 1 AS
THERMAL PROFILES WILL NOT SUPPORT MUCH DENDRITIC GROWTH. EVEN SO A
FEW INCHES OF SNOW COULD CAUSE SOME TRAVEL ISSUES AND WE WILL KEEP
A CLOSE EYE ON THIS TIME FRAME OVER THE NEXT FEW DAYS.

STRONG WINDS ARE STILL POSSIBLE IN THE FOOTHILLS AT TIMES TOO THIS
WEEK...BUT THEIR STRENGTH AND TIMING IS DEPENDENT ON THE PLACEMENT
OF THE ARCTIC FRONT...WHICH IS UNCERTAIN AFTER WEDNESDAY MORNING.

BEYOND WEDNESDAY...WE LARGELY MAINTAINED CONTINUITY WITH THE PRIOR
FORECAST THROUGH NEXT WEEKEND...BUT FORECAST UNCERTAINTY IS LARGE.
THE 12 UTC GFS AND ECMWF ACTUALLY CAME INTO CLOSE AGREEMENT WITH A
QUICK RETREAT OF THE FRONTAL BOUNDARY NORTHEAST WEDNESDAY AND THAT
WOULD LEAVE THANKSGIVING AS A VERY MILD DAY BEFORE A DEEPER PLUNGE
OF ARCTIC AIR RETURNS FRIDAY NIGHT AND SATURDAY. WE HAVE SEEN HUGE
RUN-TO-RUN SWINGS IN THE GFS AND ECMWF SOLUTIONS THE PAST FEW DAYS
AS THEY ATTEMPT TO RESOLVE IMPORTANT DETAILS OVER THE NORTHEASTERN
PACIFIC OCEAN. THUS...WHILE IT/S POSSIBLE THEY HAVE COME AROUND TO
A COMMON SOLUTION...WE CANNOT SAY SO WITH CONFIDENCE AND THUS LEFT
THE THURSDAY THROUGH SUNDAY FORECAST LARGELY AS-IS TODAY. THAT MAY
MEAN ANOTHER SHOT AT SNOW ARRIVES BY SUNDAY...BUT AGAIN CONFIDENCE
IN HOW THINGS EVOLVE BY THEN IS LOW. ANYONE PLANNING TRAVEL ACROSS
THE REGION THROUGH THE THANKSGIVING HOLIDAY WEEKEND NEEDS TO CHECK
BACK WITH THE FORECAST IN THE COMING DAYS. SCHULTZ

&&

.AVIATION...

SOUTHWEST WINDS WILL REMAIN GUSTY AT LIVINGSTON TONIGHT WITH
GUSTS TO 35KT. SCATTERED RAIN/SNOW SHOWERS WILL BE OVER THE AREA
WITH THE BEST CHANCE OF PRECIPITATION EAST OF BILLINGS. THE
MOUNTAINS WILL BE MOSTLY OBSCURED OVERNIGHT WITH OCCASIONAL SNOW
SHOWERS. VFR CONDITIONS WILL PREVAIL OVER THE LOWER ELEVATIONS.
RICHMOND
&&

.PRELIMINARY POINT TEMP/POPS...

    MON     TUE     WED     THU     FRI     SAT     SUN
-----------------------------------------------------------
BIL 025/043 027/042 027/037 022/036 023/030 007/021 010/027
    21/N    24/W    75/O    32/J    22/J    22/J    22/J
LVM 023/038 024/040 031/042 028/040 026/035 015/030 017/032
    31/N    26/J    73/R    42/W    22/W    32/J    23/J
HDN 022/041 022/041 023/036 017/035 018/031 006/024 008/028
    23/W    24/W    75/O    32/J    22/J    22/J    22/J
MLS 016/036 020/038 021/028 012/029 015/024 001/018 006/023
    23/J    43/W    46/S    42/J    22/J    22/J    22/J
4BQ 017/036 019/038 022/031 016/032 018/029 006/021 009/027
    24/W    33/W    46/S    32/J    21/B    21/B    22/J
BHK 011/029 018/034 018/023 009/024 013/023 002/015 005/021
    22/J    24/J    45/S    42/J    22/J    22/J    21/B
SHR 019/038 019/039 023/037 020/038 020/035 009/028 012/031
    22/W    24/W    54/O    22/J    21/B    22/J    12/J

&&

.BYZ WATCHES/WARNINGS/ADVISORIES...
MT...WIND ADVISORY IN EFFECT FROM 6 PM MONDAY TO NOON MST TUESDAY
      FOR ZONES 65-66.
WY...NONE.

&&

$$
WEATHER.GOV/BILLINGS



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