High Wind in Montana, May 2, 2002

SOUTH CENTRAL AND SOUTHEAST MONTANA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BILLINGS MT
212 AM MDT THU MAY 2 2002

.SHORT TERM...VALID FOR TDY...FRI...SAT...
PER ETA MODEL...SFC GRADIENT INCREASES THROUGH THE DAY AS DISTURBANCE
OVER BC BEGINS TO ELONGATE AND MOVE SOUTHWARD. WINDS WILL INCREASE
AND WITH DOWNSLOPE PATTERN IN PLACE...TEMPS WILL WARM CONSIDERABLY AS
COMPARED WITH WED. 850MB TEMPS REACH 14C BY 00Z FRI FOR HIGHS NEAR OR
AROUND 70 AT MOST LOCATIONS. TROUGH THEN BEGINS TO CROSS THE REGION BY
LATE FRI WITH TEMPS COOLING ABOUT 10 DEGREES. RH LACKING AT UPPER/LOWER
LEVELS BUT SHOWS UP AT MID LEVELS WITH FRONTAL PASSAGE AND BELIEVE
ISOLATED PRECIP BEST WITH SUCH A FAST MOVING SYSTEM. COOL DOWN IS BRIEF
WITH NORTH FLOW SHIFTING TO THE SOUTH BY SAT...TEMPS WARM ONCE AGAIN.
DYNAMICS MORE IMPRESSIVE AT MID LEVELS WITH THE AVN WITH GOOD OMEGA
SHOWING UP OVER THE SE CORNER BY 18Z FRI AND HOLDING FAIRLY STATIONARY
THROUGH 06Z SAT. SIGNIFICANTLY HIGHER PRECIP VALUES SHOWING UP AS A
RESULT OVER/ALONG THE MT/WY BORDER DURING THIS TIME FRAME AND BELIEVE
THIS TO BE OVERDONE. AVN TIMING SLIGHTLY DIFFERENT WITH SYSTEM ON FRI...
APPEARS TO BE SLIGHTLY FASTER WITH FROPA AROUND THE BIL AREA BY 18Z. AVN
ALSO SHOWS DEVELOPING LOW OVER NORTHERN HALF OF WY BY 00Z SUN KEEPING
NORTHERLY FLOW IN PLACE AND CONDITIONS COOL AS CLOUD COVER LINGERS. WHEN
COMPARING UPPER LEVEL FEATURES TO WV PICS AND LOOKING AT PREVIOUS MODEL
RUNS...NO SIGNIFICANT DIFFERENCES SHOW UP AND WILL GO WITH A BLEND OF
THE TWO MODELS AS WAS DONE ON PREVIOUS PACKAGE. DAY SHIFT WILL NEED TO
LOOK AT NEXT MODEL RUN TO REFINE FROPA TIMING AND ADJUST TEMPS UP/DOWN
ACCORDINGLY. SPRINGER

.LONG TERM...VALID FOR SUN...MON...TUE...WED...
NEW AVN...ECMWF AND UKMET IN GOOD AGREEMENT SUN WITH A TROUGH AND 500MB
LOW MOVING INTO NORTHERN WA SUN AND MON WITH EMBEDDED WAVES EJECTING
OUT OF IT ACROSS NW MT. MOST OF THE DYNAMICS AND PRECIP WILL REMAIN TO
OUR NORTH FOR SUN AND MON. WEST TO SOUTHWEST WINDS WILL PREVAIL
PROVIDING FOR GOOD DOWNSLOPING SUN AND MON WHICH WILL ALLOW TEMPS TO BE
NORMAL OR SLIGHTLY ABOVE. LOOKS AS IF THERE MAY BE LESS CLOUDS AROUND
SUN AND MON SO WILL CHANGE WORDING IN FORECAST TO REFLECT THIS. MODELS
THEN SHOW THE TROUGH SLIDING A BIT FARTHER SOUTH INTO OREGON AND IDAHO
TUES AND WED AND CONTINUING TO EJECT WAVES OUT OF IT ACROSS THE NORTHERN
ROCKIES. AS A RESULT...THE WAVES WILL BE FARTHER SOUTH THAN ON SUN AND
MON PROVIDING FOR A BETTER CHANCE OF PRECIP MON NIGHT THROUGH WED. TEMPS
WILL THEN TURN COOLER TUES AND WED TO BELOW NORMAL VALUES AS A RESULT OF
LOWER HEIGHTS...CLOUDY SKIES AND SHOWERS ACROSS THE AREA.  HOOLEY

    TDY FRI     SAT     SUN     MON     TUE     WED
-------------------------------------------------------
BIL 069 043/059 035/064 038/068 036/064 033/051 033/051
    0/N 02/N    20/E    22/B    22/B    44/W    33/W
LVM 067 040/058 035/061 037/064 034/062 031/049 031/049
    0/N 02/N    20/E    22/B    23/W    44/W    33/W
HDN 070 043/061 034/065 040/069 035/065 030/053 030/053
    0/N 02/N    20/E    22/B    22/B    44/W    33/W
MLS 070 044/059 035/065 036/069 034/066 030/053 030/053
    0/N 02/N    20/B    20/B    22/B    44/W    33/W
4BQ 069 043/059 036/066 035/069 033/065 029/053 029/052
    0/N 02/N    20/B    00/B    02/B    44/W    33/W
BHK 068 044/058 033/065 034/067 032/064 028/050 028/050
    0/N 02/N    20/B    00/B    22/B    44/W    33/W
SHR 068 042/061 034/065 035/068 035/064 031/052 031/052
    0/N 02/N    20/E    00/B    02/B    44/W    33/W

.BYZ...NONE.