Heavy Snow in Montana, April 16, 2002

SOUTH CENTRAL AND SOUTHEAST MONTANA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BILLINGS MT
211 AM MDT TUE APR 16 2002

.SHORT TERM...VALID FOR TDY...WED...THU...
POWERFUL SHORTWAVE WILL PUSH HEAVY SNOW BANDS ACROSS SOUTH CENTRAL
MONTANA EAST THIS MORNING. HEAVY SNOW BAND HAS BEEN TRAINING OVER
YELLOWSTONE COUNTY MOST OF NIGHT. BAND FINALLY SHIFTING EAST AND
WEAKENING. LIGHT SNOW SHOULD CONTINUE TO MID MORNING IN THE WEST BEFORE
TAPERING OFF. WILL LET WARNINGS/ADVISORIES EXPIRE AT 5 AM. TEMPS ARE
MUCH WARMER IN THE EAST...SO PRECIP WILL START OUT AS RAIN...THEN MIX
WITH SOME SNOW IN THE NORTH...BUT DO NOT EXPECT TO SEE THE SNOW AMOUNTS
THAT THE WESTERN ZONES HAVE SEEN WITH WARMER TEMPS. SYSTEM PULLS OUT
INTO NORTH DAKOTA THIS AFTERNOON. ETA SEEMS TO BE HANDLING THIS BEST.

ZONES WILL SEE A BREAK TONIGHT AS WEAK SHORTWAVE RIDGING BUILDS INTO
ZONES AHEAD OF NEXT UPPER LOW DROPPING INTO PACIFIC NORTHWEST. MODELS
IN GOOD AGREEMENT WITH NEXT SYSTEM AFFECTING REGION BY WEDNESDAY
AFTERNOON.

ENERGY SPLITS OFF LOW AND PUSHES INTO SOUTHERN MONTANA WEDNESDAY
AFTERNOON AND NIGHT. MODELS HAVE BEEN SHOWING GOOD CONSISTENCY WITH
THIS SYSTEM. IMPRESSIVE DEFORMATION ZONE SETS UP OVER SOUTHERN MONTANA
WEDNESDAY NIGHT PROVIDING DEEP LIFT...CONTINUING INTO THURSDAY. ALSO...
COOLER AIR PROGGED TO PUSH INTO ZONES FROM CANADA...WITH UPSLOPE FLOW
DEVELOPING AT SFC. MODELS ALSO SHOWING SFC TROUGH ACROSS SOUTHERN
MONTANA EXTENDING FROM MAIN SFC LOW IN SOUTH DAKOTA. THIS SYSTEM LOOKS
LIKE A REPEAT OF MONDAYS SYSTEM...WITH RAIN CHANGING OVER SNOW
QUICKLY...AND HEAVY SNOW POSSIBLE AGAIN. STILL A LITTLE FAR OUT FOR
WINTER STORM WATCH. WILL PUT OUT A SPS TO COVER CHANCE OF SIGNIFICANT
PRECIP AGAIN. SCARLETT

.LONG TERM...VALID FOR FRI...SAT...SUN...MON...

UNSETTLED WEATHER AND COOL TEMPS STILL EXPECTED FOR MOST OF THE
EXTENDED PACKAGE. ALL MODELS EXCEPT THE MRF PLACE A CUTOFF LOW IN THE
VICINITY OF NEVADA ON FRI. THE MRF TRIES TO CLOSE IT OFF BUT IT DOES
NOT QUITE DO SO. SFC HIGH PRESSURE ACROSS THE CANADIAN BORDER WILL HELP
TO REINFORCE THE COOL AIR THAT IS ALREADY IN PLACE ACROSS THE FORECAST
AREA. BY LATE SAT...THE CLOSED LOW BEGINS TO OPEN UP AND MOVE NORTHEAST
TOWARDS WYOMING. HOWEVER...THE MRF HOLDS IT BACK ACROSS NORTHERN UTAH.
AT THE SAME TIME...SFC LOW IN WESTERN COLORADO GETS SHUNTED TO THE SOUTH
AS A RESULT OF HIGH PRESSURE IN NORTH DAKOTA. AS A RESULT...QPF AMTS
LOOK LOW SO ONLY ISOLD SHOWERS CAN BE EXPECTED...MAINLY FRI AND SAT.
WILL CONTINUE TO KEEP TEMPS COOL FOR THIS TIME OF YEAR AS THICKNESS
VALUES FRI WILL BE AROUND 530DAM...WITH SATURDAY THICKNESS VALUES NOT
CHANGING MUCH. HOWEVER...TEMPS SAT WILL BE SEVERAL DEGREES WARMER THAN
FRI AS A RESULT OF MORE SUNSHINE. THICKNESS VALUES BY MONDAY WILL RISE
TO AROUND 546DAM WHICH IS STILL COOL FOR THIS TIME OF YEAR. GUIDANCE
TEMPS KEEP READINGS IN THE 50S AND BELIEVE THIS LOOKS GOOD. HOWEVER...
WILL LEAVE MON TEMPS AS IS FOR NOW.  HOOLEY

    TDY WED     THU     FRI     SAT     SUN     MON
-------------------------------------------------------
BIL 043 030/049 030/039 028/043 030/050 035/054 038/064
    4/J 02/W    77/S    22/E    22/B    22/B    22/E
LVM 042 030/045 028/038 025/042 028/048 032/053 037/062
    8/S 26/W    88/S    22/E    22/B    22/B    22/E
HDN 045 028/050 029/040 027/045 031/051 033/055 040/065
    8/S 02/W    77/S    22/E    22/B    22/B    22/E
MLS 049 030/058 033/047 026/044 028/053 032/054 039/062
    8/R 02/W    44/W    22/E    22/B    22/B    22/E
4BQ 048 030/057 034/044 027/047 031/054 034/055 038/061
    6/R 02/W    66/R    22/E    22/B    22/B    22/E
BHK 051 028/059 032/045 024/043 026/050 033/053 038/060
    8/R 02/W    44/W    22/E    22/B    22/B    22/E
SHR 050 027/055 027/046 027/043 027/049 032/054 037/065
    6/J 03/W    77/R    22/E    22/B    22/B    22/E

.BYZ...HEAVY SNOW WARNING MUSSELSHELL AND GOLDEN VALLEY COUNTIES TIL
       5AM. HEAVY SNOW WARNING ABOVE 6000 FEET PARTS OF SOUTH CENTRAL
       MONTANA TIL 5AM. WINTER WEATHER ADVISORY BELOW 6000 FEET PARTS OF
       SOUTH CENTRAL TIL 5AM.
       SPS FOR ENTIRE CWA.

MTZ028>042-056>058-WYZ098-099-162200-

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE BILLINGS MT
338 AM MDT TUE APR 16 2002

...ANOTHER ROUND OF WINTER WEATHER POSSIBLE WEDNESDAY NIGHT AND
   THURSDAY...

ANOTHER ROUND OF WINTER WEATHER IS POSSIBLE FOR SOUTHERN MONTANA AND
SHERIDAN COUNTY WYOMING BY MID WEEK. ANOTHER PACIFIC SPRING STORM IS
EXPECTED TO MOVE INTO THE PACIFIC NORTHWEST TONIGHT...THEN INTO THE
ROCKY MOUNTAINS WEDNESDAY.

SHOWERS WILL DEVELOP AHEAD OF THIS SYSTEM WEDNESDAY AFTERNOON...WITH
RAIN POSSIBLY BECOMING MORE WIDESPREAD WEDNESDAY EVENING. THE RAIN
IS EXPECTED TO MIX WITH THEN CHANGE OVER TO SNOW WEDNESDAY NIGHT AND
CONTINUE INTO THURSDAY.

HOWEVER...IT IS STILL TOO EARLY TO DETERMINE THE EXACT PATH OF THIS
STORM AND HOW MUCH PRECIPITATION WILL FALL. THERE IS POTENTIAL FOR
ANOTHER SIGNIFICANT PRECIPITATION EVENT FOR SOUTHERN MONTANA.

FOR ADDITIONAL WEATHER INFORMATION...CHECK OUR WEB SITE AT
HTTP://WWW.WRH.NOAA.GOV/BILLINGS/

WCJIN-WYNW-WYNE

JRS