HAMweather.com Area Forecast Discussion for County Warning Area BYZ

Thu, 16 Feb 2012 13:12:07 GMT
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BILLINGS MT 
246 AM MST THU FEB 16 2012

.SHORT TERM...VALID FOR TDY AND FRI...

RELATIVELY MINOR CHANGES TO THE SHORT TERM PERIOD THIS MORNING.
APPEARS THAT AT LEAST A SLIGHT CHANCE FOR PRECIP WILL BE POSSIBLE
THROUGH THE BULK OF THE SHORT TERM PERIOD.

THE UPPER LEVEL RIDGE POISED IN THE INTER MOUNTAIN WEST PUSHES
SLIGHTLY EASTWARD TODAY ALLOWING FOR A GOOD WARM UP FOLLOWING A
RELATIVELY COOL START TO THE DAY. TEMPS SHOULD RISE TO MID TO
UPPER 40S TODAY. THERE IS AN INVERTED SFC TROF PUSHING INTO THE
REGION TODAY...BUT INITIALLY DRY CONDITIONS AND DOWNSLOPE FLOW
SHOULD LIMIT DEVELOPMENT TO SCATTERED MOUNTAIN SHOWERS TODAY.
TONIGHT APPEARS TO BE A BIT DIFFERENT STORY...AS A STRONGER SHORT
WAVE PUSHES INTO THE AREA. PWATS ARE STILL PRETTY LIMITED...BUT DO
APPEAR TO IMPROVE THROUGH THE DAY. HAVE CONTINUED WITH INHERITED
POPS...BUT SPREAD THEM EASTWARD TO COVER THE REGION FOR FRIDAY
MORNING AND EARLY AFTERNOON. THE SHORTWAVE KICKS QUICKLY
SOUTHEASTWARD...AND THE RIDGE SHIFTS FURTHER EASTWARD FRIDAY
EVENING TO CLEAR OUT THE REGION. TEMPS WILL BE COOLER
FRIDAY...AROUND 40...WITH CLOUD COVER...SCATTERED SHOWERS...AND
PUSH OF COLD AIR INTO THE REGION. HAVE ALSO COOLER FRIDAY NIGHT
LOWS OFF SIGNIFICANTLY UNDER EXPECTED CLEAR SKIES. AAG.

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

PROGRESSIVE PATTERN IN THE EARLY PART OF THE EXTENDED AS A SHORT
LIVED RIDGE MOVES THROUGH MONTANA ON SATURDAY...BRINGING A WARMUP
INTO THE MID AND UPPER 40S FOR MOST OF THE AREA. WESTERN ZONES
WILL SEE SOME MOIST DIFFLUENT FLOW BY THE AFTERNOON AND EVENING ON
SATURDAY AND THIS SHOULD ALLOW FOR SHOWER ACTIVITY TO READILY
FORM. 

BY SUNDAY MORNING A TROUGH IS WORKING ITS WAY INTO THE WESTERN
HALF OF THE STATE WITH THE MODELS A BIT MORE CONVINCED THAT A WEAK
UPPER LEVEL LOW WILL DEVELOP OVER NORTHERN MONTANA AND SOUTHEAST
ALBERTA DURING THE DAY. NORMALLY THIS IS A DRY SOLUTION BUT THERE
IS A SECOND PIECE OF ENERGY DIGGING INTO UTAH WHICH HAS A
SUBTROPICAL TAP SO THERE IS MOISTURE IN THE TROUGH AXIS OVER
SOUTHERN MONTANA AND NORTH CENTRAL WYOMING. THIS MOISTURE MAY BE
DEEP ENOUGH TO COMPENSATE FOR A LACK OF DYNAMICS TO ALLOW SHOWER
ACTIVITY TO HAVE PRETTY DECENT COVERAGE. 

TROUGH AXIS MOVES LITTLE FOR MONDAY SO WITH MOISTURE ALREADY IN
THE REGION EXPECT ADDITIONAL SHOWER ACTIVITY WITH ONE PARTICULAR
AREA TO WATCH FOR BETTER PRECIPITATION. A WAVE SPINNING UP IN THE
LEE OF THE WYOMING/COLORADO ROCKIES HELPS DEEPEN AN INVERTED
SURFACE TROUGH OVER EASTERN WYOMING AND SOUTHEAST MONTANA. THIS
COULD BECOME THE FOCUS FOR A BAND OF STEADY PRECIPITATION WITH
ENOUGH DYNAMIC COOLING TO BECOME AN AREA OF SNOWFALL. GFS IS
WEAKER WITH THIS FEATURE THAN THE ECMWF PARTICULARLY BECAUSE THE
GFS HAS THE TROUGH TAKING ON A MORE POSITIVELY TILT WHICH WEAKENS
THE DYNAMICS. GIVEN A PRETTY QUIET EXTENDED FORECAST THIS FEATURE
MAY BE THE MOST IMPORTANT WEATHER EVENT SO WILL HAVE TO WATCH
SUNDAY NIGHT AND MONDAY CLOSELY. 

TUESDAY AND BEYOND...MOIST NORTHWEST FLOW ALOFT WITH SURFACE
PATTERN SUPPORTING MIXING. THIS SHOULD KEEP OVERNIGHT LOW
TEMPERATURES FROM FALLING MUCH BELOW 20 AND THIS ALLOWS DAYTIME
TEMPS TO CONSISTENTLY REACH THE MID 40S. SHOWERS WILL LIKELY CROSS
THE REGION AS DISTURBANCES PASS THROUGH WITH THE MOUNTAINS SEEING
STEADY ACCUMULATING SNOW. BORSUM 

.AVIATION...

MOSTLY CLEAR THROUGH THE MORNING WITH INCREASING HIGH CLOUDS THIS
AFTERNOON AND EVENING. SOUTHWEST WINDS AT KLVM 20 TO 25 KTS AT
KLVM AND 15 TO 20 KTS FOR KBIL. BORSUM 

.PRELIMINARY POINT TEMP/POPS...

    TDY FRI     SAT     SUN     MON     TUE     WED     
-------------------------------------------------------
BIL 047 025/041 021/047 027/039 021/038 023/044 024/043
    1/N 32/W    01/B    43/J    22/J    13/J    33/W
LVM 044 023/040 018/046 022/039 017/037 018/040 021/039
    2/W 42/J    02/W    53/J    22/J    23/J    33/J
HDN 048 022/042 017/048 025/041 021/041 021/045 024/045
    1/N 32/W    01/B    33/J    22/J    12/J    33/J
MLS 045 018/039 017/046 025/041 022/039 022/044 024/043
    1/B 22/J    01/B    22/J    22/J    12/J    33/J
4BQ 044 021/038 017/045 025/040 021/039 021/043 023/042
    1/N 12/J    11/U    13/J    32/J    12/J    33/J
BHK 042 017/036 014/045 022/041 019/038 019/041 024/039
    1/B 12/J    11/U    12/J    22/J    12/J    33/J
SHR 044 020/038 014/046 022/040 018/038 018/041 022/040
    1/B 32/J    11/U    34/J    32/J    12/J    34/J

.BYZ WATCHES/WARNINGS/ADVISORIES...
MT...NONE.
WY...NONE.