Heavy Snow in Wyoming, March 6, 2003

SOUTH CENTRAL AND SOUTHEAST MONTANA FORECAST DISCUSSION...COR CCF
NATIONAL WEATHER SERVICE BILLINGS MT
253 PM MST THU MAR 06 2003

.SHORT TERM...VALID FOR FRI AND SAT...

WAS WORRIED ABOUT FRONTAL POSITION AND MODELS POOR HANDLING OF THIS
SYSTEM YESTERDAY AFTERNOON...AND FEARS WERE CONFIRMED THIS MORNING AS
FRONT HAS PUSHED ALL THE WAY TO CASPER WYOMING. ARCTIC AIRMASS IS ABOUT
4 TO 5 THOUSAND FEET THICK OVER BILLINGS AND CONTINUES TO SLOWLY BUILD
UP. BETWEEN 800 AND 600 MB A STRONG MOIST WESTERLY FLOW IS PUSHING OVER
THE TOP OF THIS COLD AIR DOME INTO A VERY UNSTABLE LAYER OF THE
ATMOSPHERE...CREATING A SUSTAINED SNOW PRODUCING BAND ALONG AND JUST
NORTH OF THE MOUNTAINS IN SOUTHERN ZONES WITH OVER 8 INCHES ALREADY
THIS MORNING AT RED LODGE SKI AREA. MODELS ARE FORECASTING THE NEXT
PACIFIC WAVE TO FORCE COLD AIR OUT OF MOST OF THE CWA OVERNIGHT
TONIGHT...BUT GIVEN POOR POSITIONING OF THIS AIRMASS COMBINED WITH
CURRENT DEPTH OF ARCTIC DONT THINK THIS WILL HAPPEN. THERE WILL BE SOME
REDUCTION IN DEPTH OF THE COLD AIR...ESPECIALLY IN SHERIDAN COUNTY.
THE RESULT OF THIS SHALLOWING COULD BE TO SPREAD BEST ISENTROPIC
LIFT FURTHER NORTH RESULTING IN LARGE AREA OF MODERATE TO HEAVY SNOW AT
TIMES SOUTH OF LINE FROM HARLOWTON TO HARDIN TO ALZADA TONIGHT. THIS
COULD BE A GOOD 48 HOURS WORTH OF HEAVY SNOW FOR THE MOUNTAINS WITH
SEVERAL FEET OF SNOW POSSIBLE. WILL CONTINUE THE HEAVY SNOW WARNINGS AND
THE SNOW ADVISORY IN EASTERN CARBON...SOUTHERN BIGHORN...AND SHERIDAN
COUNTIES THROUGH LATE TONIGHT...AND DROP ADVISORIES ELSEWHERE.

TOMORROW...ARCTIC LOBE SHOULD DROP INTO THE AREA REINFORCING ALREADY
STRONG FRONTOGENESIS. THIS SHOULD LEAD TO ANOTHER DAY OF OF AND ON
SNOW WITH MORE PERSISTENT SNOW ALONG THE FRONTOGENESIS BOUNDARY AND
ALONG THE STALLED OUT FRONT ALONG THE MOUNTAINS. POSITION OF
FRONTOGENESIS IS A BIG QUESTION AS CURRENT MODELS OUT OF SINK WITH
WHATS HAPPENING NOW AND WITH MOST FEATURES ALOFT. FOR NOW WILL
BROADBRUSH IN LIKELY OR BETTER POPS WITH CATEGORICAL POPS IN THE SOUTH
AND WEST.

FOR FRIDAY NIGHT AND SATURDAY...PICTURE IS PRETTY MURKY AT THIS POINT
BUT DO EXPECT NUMEROUS FORCING ITEMS IN THE AREA...IE FRONTOGENESIS...
WEAK DISTURBANCES...AND JET ENERGY. EXACT POSITION OF THESE FEATURES
IS A GUESS AT THIS POINT SO WILL NOT TRY TO GET CUTE WITH POPS AS
EVERYBODY IS LIKELY TO SEE SNOW FRIDAY NIGHT AND WILL LEAVE CURRENT
CHANCE POPS IN FOR SATURDAY.

WITH COLD AIR AS DEEP AS IT IS NOW WILL NOT SEE MUCH CHANGE IN
TEMPERATURES OVER THE NEXT COUPLE OF DAYS WITH HIGH TEMPERATURES ONLY A
FEW DEGREES WARMER THAN OVERNIGHT LOWS. TEMPERATURES A GOOD 20 TO 30
DEGREES BELOW AVERAGE FOR THIS TIME OF YEAR. CHAMBERS

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

MODELS NOT HANDLING CURRENT SITUATION WELL. THEREFORE NOT REAL
CONFIDENT IN EXTENDED PACKAGE. ARCTIC STILL HANGS IN HERE FOR ONE MORE
NIGHT SATURDAY NIGHT BEFORE MOVING OUT EARLY IN THE COMING WEEK. GFS
PUSHES IT OUT OF OUR ENTIRE FORECAST AREA ON SUNDAY. THIS SEEMS A BIT
TOO FAST AND BELIEVE COLD AIR WILL STILL BE AROUND...ALTHOUGH READINGS
SUNDAY SHOULD BE A GOOD 10 TO 20 DEGREES WARMER IN SOME LOCATIONS THAN
ON SATURDAY. HOWEVER...TEMPERATURES WILL STILL STRUGGLE TO MAKE IT INTO
THE LOWER 30S IN THE WEST WITH LOWER TO MIDDLE 20S OUT EAST. UPPER LEVEL
FLOW WILL MAINLY BE NORTHWEST THROUGH TUESDAY. CHANCE OF SNOW SHOWERS
LOOKS GOOD FOR SUNDAY AS ARCTIC BOUNDARY WILL STILL BE IN THE AREA BUT
IN THE PROCESS OF MOVING OUT. BY MONDAY...A DECENT WAVE WILL MOVE OVER
THE AREA WITH THE STRONGEST PORTION REMAINING OVER NORTHEAST MONTANA. IN
ADDITION...A SURFACE LOW IN ALBERTA WILL MOVE SOUTHEAST INTO NORTH
DAKOTA BY MONDAY EVENING. THIS WOULD ALLOW SURFACE WINDS TO BECOME WEST
TO NORTHWEST FOR THE AREA PROVIDING FOR DOWNSLOPE FLOW AND KEEPING THE
LOWER LAYERS DRY. HOWEVER...WAVE STILL LOOKS GOOD ENOUGH TO WARRANT A
CHANCE FOR SNOW SHOWERS.
TUESDAY THROUGH THURSDAY...GFS AND ECMWF CONTINUE TO BUILD A RIDGE INTO
THE REGION. ALTHOUGH DIFFERENCES EXIST BY WEDNESDAY AS THE ECMWF
BRINGS ANOTHER WAVE THROUGH WHICH WOULD FLATTEN THE RIDGE AND ALLOW FOR
COOLER TEMPERATURES. ON THE OTHER HAND...THE GFS CONTINUES
ITS RIDGE OVER THE AREA WITH GUIDANCE TEMPERATURES WARMER THAN
YESTERDAYS. THEREFORE...WILL NOT CHANGE EXTENDED MUCH FROM PREVIOUS
PACKAGE AND WILL KEEP TEMPERATURES CLOSER TO CLIMATOLOGY WITH READINGS
SLOWLY RISING THROUGH THE 40S DURING THIS TIME.  HOOLEY

    FRI     SAT     SUN     MON     TUE     WED     THU
-----------------------------------------------------------
BIL 007/013 010/013 008/033 018/029 018/041 026/044 028/046
    ++/S    74/S    43/J    33/J    30/B    00/B    00/B
LVM 005/016 007/016 010/036 017/033 017/044 032/047 034/049
    ++/S    74/S    43/J    33/J    30/B    00/B    00/B
HDN 006/014 008/014 009/031 017/029 017/042 025/045 027/047
    ++/S    74/S    43/J    33/J    30/B    00/B    00/B
MLS 000/011 003/011 901/024 017/024 017/039 021/044 023/046
    66/S    63/S    33/J    33/J    30/B    00/B    00/B
4BQ 008/015 011/015 005/027 020/027 020/039 023/045 025/049
    99/S    63/S    33/J    33/J    30/B    00/B    00/B
BHK 000/011 003/011 902/020 015/022 015/033 018/042 020/045
    66/S    63/S    33/J    33/J    30/B    00/B    00/B
SHR 008/016 011/016 009/032 020/030 020/042 028/045 030/047
    ++/S    74/S    43/J    33/J    30/B    00/B    00/B

.BYZ...
MT...HEAVY SNOW WARNING THROUGH THIS EVENING FOR ZONES
.MTZ034...MTZ040>041...MTZ056.

WINTER WEATHER ADVISORY FOR SNOW THROUGH THIS EVENING FOR ZONES
.MTZ038>039.

WY...HEAVY SNOW WARNING THROUGH THIS EVENING FOR ZONE
.WYZ098.

WINTER WEATHER ADVISORY FOR SNOW THROUGH THIS EVENING FOR ZONE
.WYZ099.

MTZ028>042-056>058-WYZ098-099-071200-

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE BILLINGS MT
956 AM MST THU MAR 6 2003

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

.DAY ONE...
VARIOUS HEAVY SNOW WARNINGS AND WINTER WEATHER ADVISORIES HAVE BEEN
ISSUED FOR PORTIONS OF SOUTH CENTRAL...SOUTHEAST MONTANA AND NORTH
CENTRAL WYOMING. 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
HOOLEY