720
FXUS65 KBYZ 191651
AFDBYZ
AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE BILLINGS MT
951 AM MST TUE NOV 19 2019
UPDATE
TWEAKED POPS A LITTLE TODAY BASED ON THE LATEST HIGH RES
GUIDANCE. WHILE WEBCAMS HAVE NOT SHOWN ANYTHING REACHING THE
GROUND UNDER THE HIGHER RADAR ECHOS ACROSS THE WESTERN ZONES,
THERE WERE SOME INDICATIONS OF VIRGA. GIVEN THE HRRR SHOWING MORE
OF A PRECIP CHANCE THAT THE FORECAST HAD, JUST UPPED THE POPS A
LITTLE. OTHERWISE, NOT MAJOR CHANGES TO THE FORECAST. REIMER
SHORT TERM...VALID FOR TDY AND WED
BIGGEST CHANGE TO THE FORECAST WAS TO DELAY THE ONSET OF
PRECIPITATION OVER THE AREA TODAY. SYSTEM THAT WILL BRING THE
PRECIPITATION WAS SEEN MOVING ONTO THE PACIFIC NW COAST IN WATER
VAPOR IMAGERY THIS MORNING AS AN UPPER TROUGH. MODELS WERE IN GOOD
AGREEMENT IN SPLITTING THE TROUGH AND HAVING THE NORTHERN BRANCH
CROSS THE AREA TONIGHT THROUGH WEDNESDAY NIGHT. ENSEMBLES SHOWED
THAT PW'S WILL BE A LITTLE ABOVE NORMAL DURING THE PERIOD, WITH
THE BULK OF THE QPF N OF THE AREA. GEFS MEAN QPF WAS /0.10/ IN.
OR LESS. THERE WAS SOME SPREAD IN THE QPF, WHICH COULD POSSIBLY
RESULT IN A FEW INCHES OF SNOW AROUND KLVM AND KSHR, BUT THERE WAS
NOT ENOUGH CERTAINTY TO MAKE THAT CHANGE TO THE FORECAST. CIPS
ANALOG FOR LATE NOVEMBER SHOWED MAINLY 1-2 IN. OF SNOWFALL ACROSS
THE AREA WITH SIMILAR QPF'S TO CURRENT SYSTEM, AND 3 IN. OF SNOW
IN KLVM AND KSHR.
FOR THE FORECAST, KEPT THE MORNING ALMOST COMPLETELY DRY, THEN
BROUGHT A CHANCE OF RAIN INTO THE NW HALF OF THE AREA, WITH SNOW
AND RAIN OVER THE WESTERN MOUNTAINS. IT WILL BE COOLER WITH HIGHS
IN THE UPPER 40S TO MID 50S. A COLD FRONT PUSHES S THROUGH THE
AREA TONIGHT, USHERING IN A CHANCE OF RAIN THAT CHANGES TO MOSTLY
SNOW OVERNIGHT. LOOKING AT CHANCES FOR FREEZING DRIZZLE SHOWED
THAT KBHK HAD THE BEST POSSIBILITY OF THIS OVERNIGHT. HOWEVER, NBM
STILL INDICATED THE POSSIBILITY FURTHER W, SO KEPT THE CHANCE OF
ZL FOR AREAS E OF KBIL TO KSHR, SIMILAR TO PREVIOUS FORECAST.
LIGHT SNOW WILL OCCUR OVER THE AREA ON WEDNESDAY WITH POSSIBLE ZL
E IN THE MORNING. SNOW WILL TAPER OFF N TO S WED. EVENING. TOTAL
SNOW AMOUNTS WILL RANGE FROM LESS THAN AN INCH OVER THE PLAINS TO
SEVERAL INCHES IN THE MOUNTAINS AND FOOTHILLS, WITH LOCALLY HIGHER
AMOUNTS OVER PORTIONS OF THE MOUNTAINS. WILL CONTINUE TO WATCH THE
MODEL TRENDS GIVEN THE POSSIBILITIES SHOWN IN THE ENSEMBLES IN
CASE SNOW AMOUNTS NEED TO BE RAISED IN SPOTS. HIGHS WILL BE IN THE
30S WEDNESDAY. ARTHUR
LONG TERM...VALID FOR THU...FRI...SAT...SUN...MON
TEMPERATURES LOOK TO RISE AFTER THE BRIEF DIP IN THE SHORT TERM
FOR THE WEEKEND REACHING THE 50S ACROSS MUCH OF THE AREA. BUT
THEYAREN'T EXPECTED TO STAY AS ANOTHER DECREASE IS EXPECTED EARLY
NEXT WEEK TO BRING HIGHS BACK DOWN TO THE 30S BY TUESDAY.
ALTHOUGH TEMPERATURES LOOK TO RISE GOING INTO THE WEEKEND, LEE-
SIDE TROUGHING AND HIGH PRESSURE BUILDING OVER THE PACIFIC
NORTHWEST WILL HELP BRING ABOUT STRONG PRESSURE GRADIENTS OVER
SOUTH-CENTRAL MONTANA AND BRING ABOUT HIGH WINDS OVER THE
FOOTHILLS AND VALLEYS, INCLUDING AREAS FROM LIVINGSTON AND NORTH
THROUGH HARLOWTON. GOING INTO LATE SUNDAY AND MONDAY, ANOTHER
UPPER TROUGH LOOKS TO PASS OVER THE WESTERN CONUS, POSSIBLY WITH
SEMI- SPLIT FLOW AGAIN. THIS WILL BRING ANOTHER DIP IN
TEMPERATURES TO THE AREA, AS WELL AS ANOTHER SHOT OF
PRECIPITATION, THOUGH TOO MUCH UNCERTAINTY EXISTS TO NAIL DOWN ANY
SPECIFICS AT THIS TIME.
VERTZ
AVIATION
VFR CONDITIONS WILL PERSIST THROUGH TUESDAY MORNING. RAIN WILL
MOVE INTO THE AREA FROM KVLM THROUGH KBHK THROUGHOUT TUESDAY
AFTERNOON AND EVENING, AND A SWITCH TO SNOW OVERNIGHT. MOUNTAINS
WILL BE OBSCURED BEGINNING IN THE AFTERNOON AND THROUGH
WEDNESDAY. VERTZ
PRELIMINARY POINT TEMP/POPS
TDY WED THU FRI SAT SUN MON
-------------------------------------------------------
BIL 052 031/035 022/037 025/048 030/051 034/051 029/040
2/R 75/S 20/U 00/N 00/U 13/O 44/S
LVM 053 030/036 017/039 023/049 027/048 031/047 026/037
6/R 65/S 10/U 00/N 00/N 13/O 44/S
HDN 053 029/036 019/037 020/049 025/051 030/052 026/041
1/E 66/O 20/U 00/U 00/U 13/R 44/S
MLS 051 029/036 020/037 021/046 026/049 032/050 027/040
0/E 43/S 10/U 00/U 00/U 12/R 23/S
4BQ 054 029/036 019/034 020/046 025/050 030/051 026/039
0/B 26/S 40/B 00/U 00/U 02/R 33/S
BHK 047 027/034 017/034 019/043 024/046 029/048 025/037
0/E 34/S 10/B 00/U 00/U 01/B 22/S
SHR 054 027/035 015/034 015/047 022/051 027/049 022/036
0/B 48/S 71/U 00/U 00/U 12/R 34/S
BYZ WATCHES/WARNINGS/ADVISORIES
MT...NONE.
WY...NONE.
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