Severe Thunderstorm Warning 2, NWS Glasgow, MT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GLASGOW MT
243 PM MDT TUE MAY 6 2008

.SHORT TERM...FOR NORTHEAST MONTANA...TONIGHT THROUGH THURSDAY...
SHORTWAVE ENERGY PASSING THROUGH AN UNSTABLE AIRMASS HAS ALLOWED
FOR ISOLATED TO SCATTERED SHOWERS AND THUNDERSTORMS ACROSS MUCH
OF NORTHEAST MONTANA. THESE STORMS WILL CONTINUE TO TRACK TO THE
EAST ACROSS THE AREA THROUGH THE EVENING HOURS. A WEAK SURFACE
COLD FRONT WILL PUSH THROUGH THIS EVENING AS WELL...ON THE LEADING
EDGE OF A CANADIAN SURFACE HIGH. THIS FRONT WILL SERVE AS A
FOCUSING MECHANISM FOR STORMS...THUS KEPT THE HIGHEST POPS ALONG
THE CANADIAN BORDER. WEDNESDAY THE BEST POTENTIAL FOR
PRECIPITATION LIES ACROSS THE CENTRAL PART OF THE TREASURE STATE
AS A VIGOROUS MOIST LOW PRESSURE SYSTEM MOVES IN. THUS AREAS
OUTSIDE THE GLASGOW FORECAST AREAS WILL SEE THE BEST
POTENTIAL...WITH THE GLASGOW CWA SEEING FOR THE MOST PART ISOLATED
SHOWERS IN THE AFTERNOON.

WEDNESDAY NIGHT INTO THURSDAY WILL BE A DIFFERENT STORY
HOWEVER...AS THE LOW BEGINS TO IMPACT NEMONT. THERE IS DECENT
MODEL AGREEMENT DEPICTING THIS WET SYSTEM BRINGING AMPLE PRECIPITATION
TO NORTHEAST MONTANA AS TWO MID LEVEL CIRCULATIONS PUSH THROUGH.
TRENDED POPS UPWARD INTO LOW LIKELY AS WATER VAPOR DEPICTS THE
SYSTEM...NOW IN THE GULF OF ALASKA...WRAPPING UP PACIFIC MOISTURE. THAT
BEING SAID TOOK A CAUTIOUSLY OPTIMISTIC APPROACH...AS A MINOR
DEVIATION IN THE TRACK OF THE SYSTEM COULD LEAVE NORTHEAST MONTANA
HIGH AND DRY. GILCHRIST

.LONG TERM...THURSDAY NIGHT THROUGH TUESDAY...
ONLY ADJUSTMENT WORTH NOTING WAS TO INCREASE PRECIPITATION
POTENTIAL THURSDAY NIGHT TO CHANCE ACROSS MUCH OF THE CWA GIVEN
INCREASING CONFIDENCE IN THE BEHAVIOR OF A WEAK UPPER LOW OVER
NORTHEAST MONTANA. RESIDUAL SHOWERS THEREAFTER INTO SATURDAY STILL
LOOK REASONABLE UNTIL STRONGER HEIGHT RISES TAKE FOOT STARTING
SUNDAY. MCZ

PREVIOUS LONG TERM DISCUSSION...
PRECIPITATION LOOKS TO BE ABOUT NORMAL BUT TEMPS LOOK TO BE BELOW
NORMAL. CONFIDENCE AGAIN ON THE LOW SIDE WITH RESPECT TO
PRECIPITATION CHANCES AS SYSTEMS ARE MOSTLY BROKEN UP AS THEY COME
THROUGH THE AREA AND MODELS ARE NOT IN GREAT AGREEMENT WITH
SPEED...STRENGTH AND POSITION.

SYSTEM THAT AFFECTS THE AREA AT THE END OF THE SHORT TERM BEGINS
TO EXIT THE AREA THURSDAY NIGHT AND FRIDAY. THE OPERATIONAL GFS
AND IT/S RESPECTIVE ENSEMBLES BRING SOME RIDGING INTO THE AREA BY
LATE IN THE WEEKEND. THEREFORE LOW POPS LOOK GOOD INTO SUNDAY. WE
SHOULD SEE SOME MORE SUN TOO AND TEMPS MAY BEGIN TO SURGE A BIT
CLOSER TO NORMAL BY EARLY NEXT WEEK. ANOTHER TROUGH LOOKS TO
MOVE INTO THE AREA FOR EARLY NEXT WEEK AND THE GFS AND IT/S
ENSEMBLES ARE IN GOOD AGREEMENT WITH THIS. THE ECMWF IS NOT SO
DEEP WITH IT. JAMBA

&&

.AVIATION...
PREDOMINANTLY VFR. WIDELY SCATTERED THUNDERSTORMS WILL AFFECT THE
TERMINALS THRU AROUND 03Z BEFORE TAPERING TO A FEW SHOWERS OVERNIGHT.
THE STRONGEST STORMS WILL BE CAPABLE OF REDUCING VISIBILITIES TO
ONE MILE IN HEAVY RAIN WITH WIND GUSTS TO 40 KT ALONG WITH SOME
VERY SMALL HAIL. EXPECT LIGHT EASTERLY WINDS AT GGW AND OLF TO
TURN NORTHERLY TONIGHT AROUND 10 KT WHILE SDY AND GDV MAINTAIN
LIGHT NORTHERLY SPEEDS. MCZ

&&

.GLASGOW WATCHES/WARNINGS/ADVISORIES...NONE.

&&

WEATHER.GOV/GLASGOW