SOUTH CENTRAL AND SOUTHEAST MONTANA FORECAST DISCUSSION
NWS BILLINGS MT
AFDBIL 833 AM MDT WED APR 16 2003
.SHORT TERM...VALID FOR TDY AND THU...
RAIN AND SNOW ASSOCIATED WITH THE LOW OVER THE CENTRAL PLAINS CONTINUES
OVER THE FAR EASTERN ZONES THIS MORNING. THE PRECIP WILL CHANGE TO
ALL RAIN LATER TODAY AND EXIT THE AREA THIS AFTERNOON. SKIES HAVE
CLEARED OVER THE REMAINDER OF THE CWA EXCEPT FOR A BATCH OF CIRRUS
HEADING INTO THE AREA FROM THE SOUTHWEST. CIRRUS IS LOCALLY THICK BUT
NOT VERY WIDESPREAD SO PARTLY CLOUDY WORDING SHOULD COVER.
13Z ACARS SHOWS FAIRLY WELL MIXED LAYER ABOVE THE NOCTURNAL INVERSION
TO NEAR 700MB. MIX OUT OF THE INVERSION LEADS TO LOWER 50S FOR BIL...
HOWEVER MODELS SHOW WARMER AIR MOVING IN. MODELS WERE A DEGREE
COOLER AT 850-700MB THAN ACARS AND CURRENT GUIDANCE IS SUGGESTING UPPER
50S. WILL INCREASE MAX TEMPS ACROSS THE AREA WHERE CLOUD COVER WILL
BE LESS. MOORE
.LONG TERM...VALID FOR FRI...SAT...SUN...MON...TUE...
UPPER TROF ADVANCES QUICKLY INTO THE REGION THURSDAY NIGHT WITH A
CHANCE OF SHOWERS SPREADING FROM SOUTHWEST TO NORTHWEST OVERNIGHT.
TEMPERATURES WILL FALL TO AROUND FREEZING SO WILL GO WITH A RAIN SNOW
MIX BY MORNING IN THE LOWER ELEVATIONS AND SNOW ABOVE 6000 FEET.
MODELS INDICATING A STRONG AREA OF UPWARD MOTION TO DEVELOP OVER
SOUTH-CENTRAL COUNTIES...ASSOCIATED WITH AN AREA OF UPPER LEVEL
DIVERGENCE FROM RIDGE PUSHING UP FROM THE SOUTHWEST AND POSITIVE
VORTICITY ADVECTION IN BASE OF TROF...PROGRESSING NORTHEAST DURING THE
DAY FRIDAY. WILL GO WITH SLIGHTLY HIGHER POPS THERE AND GENERAL CHANCE
POPS ELSEWHERE. TEMPERATURES FRIDAY LOOK TO STAY IN THE LOWER 50S AT
BEST WITH CLOUD COVER AND WIDESPREAD SHOWER ACTIVITY CUTTING BACK ON
HEATING. COLDER AIR MOVES INTO THE AREA AT UPPER LEVELS DURING THE LATE
AFTERNOON WITH AN AREA OF -13C AIR MOVING INTO WESTERN ZONES OVERNIGHT
FRIDAY...LEADING TO THE COLDEST NIGHT OF THE EXTENDED. SNOW AND LOW
LEVEL RAIN/SNOW MIX SHOULD END FROM WEST TO EAST OVERNIGHT. FOR SATURDAY
AN UPPER LEVEL RIDGE RAPIDLY BUILDS INTO THE REGION AS A RESPONSE TO A
STRONG PACIFIC SYSTEM DIGGING UPSTREAM. TEMPERATURES WILL CLIMB A FEW
DEGREES OVER FRIDAYS HIGHS...DESPITE LITTLE CHANGE IN TEMPERATURES
ALOFT...AS SKIES SHOULD CLEAR BY AFTERNOON. SUNDAY LOOKS WARMER AS RIDGE
CONTINUES TO BUILD AND WARMER AIR ALOFT FINALLY MOVES OVER THE REGION.
WINDS WILL SHIFT TO THE SOUTHWEST FOR A SHORT TIME ALLOWING FOR BRIEF
DOWNSLOPE FLOW TO ASSIST WARMING. FOR MONDAY AND TUESDAY...MODELS IN
SOME DISAGREEMENT WITH THE HANDLING OF NEXT PACIFIC STORM SYSTEM. GFS
WANTS TO GO SIMILAR TO CURRENT SYSTEM AND SLIDE UPPER LOW THROUGH GREAT
BASIN AND COLORADO. EUROPEAN TAKES A MORE NORTHERLY TRACK INTO IDAHO AND
WYOMING. GIVEN THE DISAGREEMENT WILL NOT MAKE ANY CHANGES TO THESE
PERIODS. CHAMBERS
TDY THU FRI SAT SUN MON TUE
-------------------------------------------------------
BIL 059 035/064 034/050 033/055 038/061 042/060 037/057
0/B 02/W 44/W 40/B 00/U 03/T 33/W
LVM 057 031/064 032/048 031/054 033/059 037/054 034/054
0/B 03/W 43/W 20/B 00/B 03/T 33/W
HDN 059 033/064 033/051 032/056 037/061 041/061 036/059
0/B 02/W 44/W 40/B 00/U 03/T 33/W
MLS 053 031/063 033/049 032/054 036/060 040/062 040/060
7/R 00/B 34/W 40/B 00/U 03/T 33/W
4BQ 053 031/061 033/048 032/053 035/059 039/060 040/059
8/R 00/B 44/W 40/B 00/U 03/T 33/W
BHK 050 029/060 032/046 031/052 033/057 037/060 039/059
8/R 00/B 34/W 40/E 00/U 03/T 33/W
SHR 059 033/060 034/046 033/051 034/061 038/059 035/059
0/B 02/W 44/W 40/B 00/U 03/T 33/W
.BYZ...
MT...NONE.
WY...NONE.
$$