Severe Thunderstorm Warning 124, NWS Glasgow, MT

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE GLASGOW MT
843 PM MDT SAT JUL 7 2007

.SHORT TERM...FOR NORTHEAST MONTANA...TONIGHT THROUGH MONDAY...
MAIN UPDATE INVOLVED LIMITING THIS EVENING/S POPS TO SOUTH OF THE
MISSOURI RIVER. RADAR MOSAIC REVEALS BRUNT OF CONVECTION HAS
REMAINED SOUTH OF THE CWA CLOSER TO THE SURFACE BOUNDARY WITH JUST
A FEW DISORGANIZED STORMS HAVING PASSED ACROSS FAR SOUTHERN
PETROLEUM COUNTY IN THE LAST HOUR. RENEWED STORM DEVELOPMENT
STILL LOOKS TO ARRIVE AFTER THE MIDNIGHT HOUR STARTING IN THE
WEST. THIS WILL BE COURTESY OF A SHORTWAVE TROUGH ENTERING
NORTHWEST MONTANA WHICH SHOULD CONTINUE SHIFTING EASTWARD
OVERNIGHT AND BEGIN TO INTERACT WITH THE STALLING FRONT JUST EAST
OF THE ROCKIES. RECENT VIGOROUS UPSLOPE CONVECTION NEAR GREAT
FALLS WILL BE WATCHED CLOSELY AS THIS HAS FIRED WELL IN ADVANCE OF
THE MAIN SHORTWAVE. REMAINDER OF FORECAST ON TRACK. MCZ

PREVIOUS SHORT TERM DISCUSSION...
UPPER FLOW WILL BECOME ZONAL TONIGHT AS AN UPPER JET PUSHES ALONG
JUST NORTH OF THE INTERNATIONAL BORDER. THIS WILL GENERATE LARGE SCALE
SUPPORT AS THE FRONT CONTINUES TO PUSH PUSH SOUTH. THIS SHOULD KICK
OFF ADDITIONAL EVENING THUNDERSTORM ACTIVITY IN SOUTHERN MONTANA
INCLUDING OUR SOUTHERN ZONES. WITH INVERTED V SOUNDING LOCAL STORMS
COULD PRODUCE VERY STRONG DOWNBURSTS. DISTURBANCES IN THE UPPER
FLOW THIS EVENING ARE APPARENT IN BOTH THE GFS AND NAM. COOLER AIR
WILL CONTINUE TO MOVE SOUTH BEHIND THE FRONT WITH 850MB
TEMPERATURES DROPPING FROM 31C TO 17C IN 24 HOURS. IN ADDITION
WITH FALLING 1000-500MB THICKNESS VALUES CAN EXPECT OVERNIGHT
TEMPERATURES TO FALL CLOSER TO NORMAL.

SUNDAY AND SUNDAY NIGHT...A SECONDARY COLD FRONT PUSHES SOUTH OVER
THE REGION WHICH SHOULD INITIATE ADDITIONAL PRECIPITATION. THE
ACTIVITY SHOULD BE CONVECTIVE ALONG THE FRONT BUT THE AIR BECOMES
MUCH MORE STABLE BEHIND THE FRONT. A SURFACE HIGH FOLLOWS THE
FRONT SO SKIES SHOULD BEGIN TO CLEAR SOMEWHAT BEHIND THE
PRECIPITATION. BY LATE AFTERNOON THE PRECIPITATION SHOULD MOVE
INTO THE EASTERN ZONES AND PRETTY MUCH OUT OF THE AREA BY EVENING.
WITH PLENTY OF CLOUD COVER INITIALLY AND 850MB TEMPERATURES
FALLING TO AROUND +12C DEGREES THE MAXIMUM SURFACE TEMPERATURES
WILL STRUGGLE TO RISE TO NORMAL...WHICH WILL BE A RELIEF FROM THE
RECENT HEAT. OVERNIGHT SKIES COULD BECOME MOSTLY CLEAR WITH THE
WEAK SURFACE HIGH IN PLACE AND SUBSIDENCE ACROSS THE ZONES. SO
COULD SEE SOME PATCHY FOG...MAINLY IN THE NORTHEAST...BUT WILL
REFRAIN FROM MENTIONING FOR NOW DUE TO THE UNCERTAINTY. WITH NOT
MUCH CLOUD COVER THE OVERNIGHT LOWS WILL HAVE A REAL CHANCE TO
HOVER AROUND NORMAL.

MONDAY...A STRONG SHORTWAVE TROUGH WILL BE MOVING SOUTHEAST ACROSS
ALBERTA AND SASKATCHEWAN. A STRONG JET AROUND THE BASE OF THE
TROUGH WILL SLIDE ALONG THE INTERNATIONAL BORDER LATE IN THE
AFTERNOON. WITH YET ANOTHER COLD FRONT POISED TO MOVE INTO THE
NORTHERN ZONES DURING THE LATE AFTERNOON WENT AHEAD AND BUMPED
NORTHERN AFTERNOON POPS TO JUST BELOW SLIGHT CHANCE. THE DESERT
AIR WILL BEGIN TO MOVE NORTHEAST TOWARDS THE REGION AGAIN BEFORE
THE NEXT FRONT FROM THE NORTH PUSHES THE HEAT BACK...BUT NOT
BEFORE THE WARMER AIR HAS A CHANCE TO TAKE SOME EFFECT. SO MAXIMUM
TEMPERATURES WILL RISE TO SLIGHTLY ABOVE NORMAL. SCT

.LONG TERM...MONDAY NIGHT THROUGH SATURDAY...
GOING FORECAST IN GOOD SHAPE. MADE SOME TWEAKS TO COOL
TEMPERATURES AS NEIGHBORS TO THE SOUTH AND EAST COOLED THEIR
RESPECTIVE AREAS TUESDAY THROUGH THURSDAY. REST OF FORECAST LOOKED GOOD.
JAMBA

PREVIOUS DISCUSSION...
A DISTURBANCE IN THE NORTHWEST FLOW WILL MOVE SOUTHEAST ACROSS
CENTRAL SASKATCHEWAN MONDAY NIGHT. THIS WILL PUSH A DRY COLD FRONT
THRU THE AREA AS THE LOWER LEVELS OF THE ATMOSPHERE APPEAR TOO DRY
FOR PRECIPITATION AND THE BEST UPPER LEVEL SUPPORT WILL MISS US TO
THE NORTH. SURFACE HIGH PRESSURE WILL THEN MOVE IN FOR TUESDAY AND
REMAIN IN AT LEAST A WEAK FORM THRU FRIDAY. ALOFT AN UPPER RIDGE
OVER THE EASTERN PACIFIC TUESDAY WILL GRADUALLY MOVE EAST THRU THE
WEEK AND AMPLIFY. BY FRIDAY THIS RIDGE AXIS IS EXPECTED TO BE OVER
IDAHO OR INTO WESTERN MONTANA. THIS WILL KEEP THE UPPER FLOW
NORTHWEST TO NORTH THRU THE WEEK. RIGHT NOW MODELS INDICATE THIS
WILL BE FAIRLY DRY FLOW SO WILL KEEP THE FORECAST DRY FOR NOW.
NORTHWEST FLOW CAN BE VERY TRICKY AND THERE COULD EASILY BE A
DISTURBANCE THAT MANAGES TO EKE OUT A FEW SHOWERS OR STORMS. BUT
RIGHT NOW TRYING TO NAIL THAT DOWN WOULD BE AN EXERCISE IN
FUTILITY. TEMPERATURES WILL START OFF ON THE RELATIVELY COOL SIDE
TUESDAY IN THE WAKE OF MONDAY NIGHTS FRONT...AND GRADUALLY WARM
THRU THE WEEK AS THE UPPER RIDGE...AND WARMER AIR FROM THE
SOUTHWEST DRAW CLOSER. BY FRIDAY HIGHS SHOULD BE BACK TO AROUND
NORMAL FOR TIME OF YEAR...GENERALLY MIDDLE 80S FOR THE BULK OF THE
CWA.

&&

.AVIATION...
THUNDERSTORMS CONTINUE TO REMAIN TO THE SOUTH OF THE TAF SITES
THIS EVENING.  IT WOULD APPEAR THAT THE BEST CHANCE OF A SHOWER OR
THUNDERSTORM OVERNIGHT WOULD BE AT KGDV...ALTHOUGH MOST OF THE
CONVECTION WILL SLIDE BY ACROSS SOUTHEAST MONTANA. ADDITIONAL
SHOWERS MAY MOVE IN FROM THE WEST/NORTHWEST SUNDAY MORNING AND
COULD PRODUCE A SHOWER AT KGGW.  OUTSIDE OF ANY CONVECTION VFR
CONDITIONS ARE EXPECTED. PLEASE SEE TAFS FOR SPECIFIC DETAILS. CB

&&

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

&&

WEATHER.GOV/GLASGOW