Heavy Snow in Montana, March 7, 2003

SOUTH CENTRAL AND SOUTHEAST MONTANA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BILLINGS MT
941 AM MST FRI MAR 7 2003

.SHORT TERM...VALID FOR TDY AND SAT...

UPDATE TO ZFP AND AFP SHORTLY...

ANOTHER TRICKY FORECAST FOR TODAY AS SEVERAL VARIABLES WILL COME INTO
PLAY THROUGHOUT TODAY AND TONIGHT. CURRENT RADAR IMAGES CONTINUE TO
SHOW A LARGE AREA OF SNOW FROM WHEATLAND COUNTY EAST AND SOUTHEAST
THROUGH NORTHEAST YELLOWSTONE COUNTY INTO TREASURE AND NORTHERN ROSEBUD
COUNTIES. WITHIN THIS BROAD AREA OF SNOW THERE HAVE BEEN BANDS OF HEAVY
SNOWFALL DEVELOPING...ESPECIALLY THROUGH NORTHEAST YELLOWSTONE COUNTY
IN THE VICINITY OF POMPEYS PILLAR AND CUSTER. LATEST REPORTS FROM
HARLOWTON INTO TREASURE COUNTY SHOW AROUND 1.5 INCHES OF SNOW HAS
FALLEN ALREADY SINCE 7 AM.

MODELS CONTINUE TO NOT HANDLE CURRENT SITUATION WELL AT ALL. ALL
MODELS HAVE BEEN KEEPING THE ARCTIC OUT OF LIVINGSTON AND HOLDING IT
OVER OUR NORTHERN ZONES. HOWEVER...LIVINGSTON AFTER BEING IN THE LOWER
30S DURING THE NIGHT IS BACK DOWN TO 8 DEGREES. TEMPERATURES ACROSS THE
ENTIRE AREA ARE IN THE SINGLE DIGITS WITH THE EXCEPTION OF SHERIDAN
WHICH IS CURRENTLY AT 14 DEGREES. KEY PLAYER WITH TEMPERATURES AND
SNOW TODAY WILL BE STRONG JET ENERGY AND WAVE CURRENTLY MOVING THROUGH
NORTHERN OREGON WITH A SECOND LARGE WAVE MOVING THROUGH NORTHERN
CALIFORNIA INTO NORTHERN NEVADA. 3-HOUR PRESSURE FALLS HAVE BEEN NOTED
ACROSS SOUTHEAST MONTANA. BELIEVE THIS HAS ALLOWED THE ARCTIC AIR TO
DEEPEN OVER THE NORTHERN AND EASTERN ZONES. IN ADDITION...PLENTY OF
PACIFIC MOISTURE CONTINUES TO OVERRUN THIS ARCTIC BOUNDARY. AS A
RESULT...SNOW CONTINUES TO DEVELOP AS MENTIONED ABOVE.

NEXT PROBLEM AREA TO TACKLE IS WHEN WILL THIS BOUNDARY BEGIN TO DRIFT
SOUTH. SURFACE PRESSURE FALLS OF AROUND 1MB PER HOUR HAVE BEEN NOTED
OVER NORTHERN IDAHO. THIS IS IN RESPONSE TO ABOVE MENTIONED WAVE AND
JET MAX MOVING INTO NORTHERN OREGON. THIS AREA OF LOW PRESSURE IS
EXPECTED TO RIDE THE ARCTIC BOUNDARY SOUTHEAST CAUSING VARIOUS
NORTH/SOUTH FLUCTUATIONS OF THE ARCTIC. AS THE LOW CONTINUES ITS
SOUTHEAST PROGRESSION...BELIEVE THE ARCTIC WILL DEEPEN OVER BILLINGS
AND THE SOUTHERN ZONES. SOUNDINGS SHOW ARCTIC DEEPENING BY MID-
AFTERNOON AND CONTINUING THROUGH TONIGHT. DUE TO CONTINUING SNOWFALL
IN NORTHERN ZONES...HAVE DECIDED TO EXPAND THE WINTER WEATHER ADVISORY
FOR SNOW FOR TODAY AND TONIGHT TO INCLUDE THE REMAINING NORTHERN
COUNTIES...AS WELL AS YELLOWSTONE AND NORTHERN BIG HORN COUNTIES.
HOWEVER...MOST OF THE HEAVIER SNOW WILL REMAIN TO THE NORTH AND EAST OF
BILLINGS FOR MOST OF THE DAY. UPDATES TO ZONES AND ADVISORIES ON THE
WAY.  HOOLEY

.LONG TERM...VALID FOR SUN...MON...TUE...WED...THU...
RELATIVELY FLAT UPPER RIDGE TO BUILD INTO THE WESTERN PART OF THE AREA
SUNDAY. ARCTIC BOUNDARY PROGGED TO REMAIN OVER THE EASTERN HALF OF SOUTH
CENTRAL MONTANA. WARM AIR ADVECTION ALOFT...ALONG WITH SHORTWAVE MOVING
THROUGH AND A CONTINUOUS STREAM OF MOISTURE...TO KEEP THE CHANCE OF SNOW
SHOWERS OVER THE REGION. BOUNDARY TRIES TO PULL OUT OF SOUTH CENTRAL
MONTANA SUNDAY NIGHT AND MONDAY AS A STRONGER SHORTWAVE MOVES THROUGH
THE STATE. SHORTWAVE TO CAUSE A CHANCE OF SNOW SHOWERS...AND THIS WILL
KEEP CLOUDS AROUND AND LIMIT WARMING TO HIGHS IN THE 20S TO 30S.
SHORTWAVE TO FORCE NORTHWEST FLOW BEHIND IT FOR TUESDAY. FLOW SHOULD DRY
OUT BEHIND THE SHORTWAVE...SO WILL LEAVE IT DRY. WILL BACK OFF ON SOME
OF THE WARMING FOR TUESDAY AS REINFORCING COLD SHOT TO SLIP BACK INTO
THE EAST DURING THE DAY. UPPER RIDGE THEN BUILDS IN FULL FORCE WEDNESDAY
AND THURSDAY. MODELS PRETTY CONSISTENT ON THIS SO A WARM UP SHOULD BE IN
THE CARDS. GOING EXTENDED LOOKS IN PRETTY GOOD SHAPE AND CONFINED
CHANGES TO ABOVE. HUMPHREY

    TDY SAT     SUN     MON     TUE     WED     THU
-------------------------------------------------------
BIL 013 010/013 008/031 018/034 018/037 026/044 030/048
    +/S 84/S    43/J    33/J    30/B    00/B    00/B
LVM 015 011/016 010/034 017/038 017/041 026/047 030/051
    +/S +4/S    43/J    33/J    30/B    00/B    00/B
HDN 014 008/014 009/029 017/034 017/036 025/045 029/049
    +/S 74/S    43/J    33/J    30/B    00/B    00/B
MLS 009 003/011 901/022 017/029 017/029 021/042 025/046
    +/S +3/S    33/J    33/J    30/B    00/B    00/B
4BQ 015 009/015 005/025 020/032 020/032 023/045 027/049
    9/S 73/S    33/J    33/J    30/B    00/B    00/B
BHK 009 003/011 902/020 015/027 015/027 018/040 024/044
    9/S +3/S    33/J    33/J    30/B    00/B    00/B
SHR 016 009/016 009/030 020/035 020/037 024/045 028/049
    +/S 64/S    43/J    33/J    30/B    00/B    00/B

.BYZ...
MT...HEAVY SNOW WARNING FOR THIS AFTERNOON THROUGH LATE TONIGHT FOR
ZONES MTZ034...MTZ040>041...MTZ056.

WINTER WEATHER ADVISORY FOR TODAY AND TONIGHT FOR ZONES MTZ031>033.

WINTER WEATHER ADVISORY FOR TODAY AND TONIGHT FOR ZONES MTZ028>030...
.MTZ035...MTZ042...MTZ057.

WY...NONE.

MTZ028>042-056>058-WYZ098-099-080015-

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE BILLINGS MT
1116 AM MST FRI MAR 7 2003

THIS HAZARDOUS WEATHER OUTLOOK IS FOR SOUTH CENTRAL...SOUTHEAST
MONTANA AND NORTH CENTRAL WYOMING.

.DAY ONE...
HEAVY SNOW WARNINGS AND WINTER WEATHER ADVISORIES ARE IN EFFECT FOR
PORTIONS OF SOUTH CENTRAL AND SOUTHEAST MONTANA FOR TODAY AND
TONIGHT. REFER TO GTFWSWBYZ FOR DETAILS.

.DAYS TWO THROUGH SEVEN...
NO HAZARDOUS WEATHER IS EXPECTED AT THIS TIME.

.SPOTTER INFORMATION STATEMENT...
WEATHER SPOTTERS ARE ENCOURAGED TO REPORT SIGNIFICANT WEATHER
CONDITIONS ACCORDING TO STANDARD OPERATING PROCEDURES.

WCJIN-WYNW-WYNE