FXUS65 KGGW 260337
AFDGGW
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GLASGOW MT
837 PM MST FRI DEC 25 2009
.SHORT TERM...FOR NORTHEAST MONTANA...TONIGHT THROUGH SUNDAY...
WILL TWEAK MANY OVERNIGHT TEMPERATURES UPWARD AS CLOUDS HAVE MOVED
FARTHER WEST ACROSS THE CWA AND WARMER TO OUR EAST AND WEST HAS
FURTHER PINCHED THE ARCTIC AIRMASS STILL CLINGING OVER THE CENTRAL
PORTION OF THE CWA. TIGHT PRESSURE GRADIENT STILL REMAINS OVER THE
EASTERN ZONES ASSOCIATED WITH THE MONSTER PLAINS STORM...SO WIND
STILL QUITE EXCITED THERE. HAVE RAISED SOME WIND SPEEDS JUST A BIT
BASED ON LATEST OBSERVATIONS. HAVE ALSO ADDED MORE CLOUDS FARTHER
WEST PER LATEST OBSERVATIONS AND SATELLITE IMAGERY. REMAINDER OF
THE FORECAST LOOKS GOOD AND WILL KEEP ALL ADVISORIES AND WARNINGS
UP AND LET THE MID SHIFT FURTHER ASSESS THEIR EFFICACY.
PREVIOUS DISCUSSION...
THE MAJOR WINTER STORM CONTINUES OVER THE CENTRAL NORTHERN PLAINS
THIS AFTERNOON AND EVENING. WINTER HEADLINES CONTINUE TO LOOK GOOD
OVER THE EASTERN ZONES THROUGH SATURDAY AFTERNOON.
TONIGHT THROUGH SATURDAY...THE WINTER STORM WILL CONTINUE TO OUR
EAST AS MOST OF THE ROADS ACROSS NORTH AND SOUTH DAKOTA ARE CLOSED
WITH STATE OFFICIALS CLOSING I-94 AS WELL. THE CURRENT ANALYSIS
ALONG WITH RECENT GROUND TRUTH SHOW THAT THE SNOW ACCUMULATION IN
THE WINTER WEATHER ADVISORY COUNTIES SO FAR HAS BEEN AROUND 3
INCHES. THE WINTER STORM WARNING SEEM TO BE DOING WELL AS
VISIBILITIES IN SOUTHERN WIBAUX COUNTY HAVE BEEN ABOVE 1/4 OF A
MILE WITH SNOW TOTALS ALREADY APPROACHING 6 INCHES SO FAR. THE
WIND WILL CONTINUE BLOWING OUT OF THE NORTHWEST AT 15 TO 30 MPH
DUE TO THE SURFACE GRADIENT BETWEEN THE SURFACE LOW OVER SOUTHWEST
MINNESOTA AND THE SURFACE HIGH NUDGING IN FROM SASKATCHEWAN. WENT
AHEAD AND EXTENDED THE WIND CHILL ADVISORY FOR GARFIELD...VALLEY...WESTERN
ROOSEVELT...DANIELS AND MCCONE COUNTIES.
THE GRADIENT IS STILL STRONG ENOUGH IN THESE COUNTIES TO CAUSE
WIND CHILL PROBLEMS. IN THE WESTERN ZONES THE WIND WILL DROP DOWN
BELOW 5 MPH SO HAZARDOUS WIND CHILL CONDITIONS ARE NOT EXPECTED.
TEMPERATURES WILL STILL DROP INTO THE NEGATIVE TEENS IN SOME
PLACES IN THE WESTERN ZONES HOWEVER. THE HIGHER TERRAIN TO WEST WILL
ONLY DROP INTO THE NEGATIVE SINGLE DIGITS. THE HIGH TEMPERATURES
FOR SATURDAY IN THE WESTERN AREAS SHOULD GET INTO THE TEENS ABOVE
ZERO. ACROSS THE CENTRAL PART OF THE CWA WHERE TEMPERATURES
REMAINED IN THE NEGATIVE SINGLE DIGITS TODAY...THEY WILL FINALLY GET
ABOVE ZERO AS THE LAST OF THE ARCTIC AIR IS MODIFIED. THE SNOW
WILL CONTINUE TO FALL...BLOWING AND DRIFTING AROUND UNTIL SATURDAY
AFTERNOON IN THE EAST BEFORE COMING TO AN END. HIGHS ACROSS THE
EASTERN ZONES WILL ALSO REACH THE UPPER SINGLE DIGITS ABOVE ZERO.
SATURDAY NIGHT AND SUNDAY...THE STORM SYSTEM MOVES EAST BY SATURDAY
NIGHT AND THE SNOW ENDS AS HIGH PUSHES SOUTH OUT OF SASKATCHEWAN
AND INTO NEMONT. EXPECT 850MB TEMPERATURES TO INCREASE ABOVE ZERO
ON SUNDAY. THE REMAINDER OF THE SHORT TERM WILL BE DRY AND THE
WARM UP SHOULD CONTINUE. RSMITH
.LONG TERM...SUNDAY NIGHT THROUGH FRIDAY...
NO SIGNIFICANT CHANGES TO THE EXTENDED FORECAST. MODELS STILL
FAIRLY CONSISTENT WITH BUILDING RIDGE EARLY IN THE WEEK. SHORTWAVE
SLIDES THROUGH MONTANA ON TUESDAY THEN AN ARCTIC FRONT DROPS INTO
THE STATE. THIS REFLECTED WELL IN THE CURRENT FORECAST. EBERT
PREVIOUS LONG TERM DISCUSSION...UPPER RIDGE WILL BRING WARMER AIR
ALOFT TO EASTERN MONTANA THROUGH MONDAY. HOWEVER...WITH SNOW COVER
AND LIGHT WINDS...THE WARMER AIR WILL HAVE A TOUGH TIME REACHING
THE SURFACE OVER MOST OF THE FORECAST AREA. WHILE HIGHER ELEVATION
AREAS LIKE ZORTMAN HAS A GOOD CHANCE OF SEEING 30 DEGREES ON
MONDAY...MOST LOCATIONS WILL STRUGGLE TO GET OUT OF THE TEENS
THANKS TO A LOW LEVEL INVERSION THAT WILL LINGER UNDERNEATH THE
WARMER AIR.
A WEAK SHORTWAVE AND COLD FRONT MOVES THROUGH THE AREA ON TUESDAY
WITH LIMITED MOISTURE. WILL MAINTAIN A MAINLY DRY FORECAST FOR
NOW.
ALL OF THE MODELS BRING A COLD FRONT THROUGH THE AREA AT SOME
POINT ON WEDNESDAY...THE ECMWF IS MUCH COLDER THAN THE GFS WITH
THE AIRMASS BEHIND THE FRONT. GIVEN HOW EASY IT HAS BEEN FOR
ARCTIC AIRMASSES TO MOVE INTO EASTERN MONTANA LATELY WILL TREND
FORECAST TOWARDS COLDER ECMWF BUT NOT FORECAST THE DEEP FREEZE
THAT THE MODEL HAS FOR NE MONTANA YET. WILL MENTION A SLIGHT
CHANCE OF SNOW WITH THIS FRONT.
FOR NEW YEARS EVE...HIGH PRESSURE SHOULD BRING DRY WEATHER. MODELS
DIFFER GOING INTO NEW YEARS DAY WITH THE ECMWF BRINGING THE FRONT
BACK EAST AS A DRY WARM FRONT WHILE THE GFS SETS UP OVERRUNNING
MOISTURE BUT KEEPS THE FRONT STATIONARY TO THE SOUTH. WILL MENTION
A SLIGHT CHANCE OF SNOW WHILE THE MODELS SORT THINGS OUT. FORRESTER
&&
.AVIATION...
VFR CONDITIONS WILL PREVAIL AT KGGW AND KOLF THRU THE WEEKEND.
SOME BROKEN MID CLOUDS MAY INTERMITTENTLY MOVE THRU IN FLOW AROUND
A MONSTER UPPER LOW PRESSURE SYSTEM AFFECTING MUCH OF THE MIDWEST
AND PLAINS. KSDY AND KGDV WILL REMAIN JUST INSIDE THE EDGE OF THE
CLOUDS AND LIGHT SNOW ROTATING AROUND THE AFOREMENTIONED
SYSTEM...RESULTING IN PREVAILING MVFR CONDITIONS WITH SOME
OCCASIONAL IFR CONDITIONS INTO OR THRU MUCH OF SATURDAY. A
NORTHWEST WIND WILL PREVAIL AT ALL SITES THRU SATURDAY WITH SPEEDS
AT KGGW AND KOLF GENERALLY AROUND 15 KT OR LESS. KSDY AND KGDV
WILL BE UNDER A TIGHTER PRESSURE GRADIENT WITH RESULTANT SPEEDS OF
GENERALLY 15 TO 25 KT WITH OCCASIONAL GUSTS 30 KT.
&&
.GLASGOW WATCHES/WARNINGS/ADVISORIES...
WIND CHILL ADVISORY UNTIL 11 AM MST SATURDAY FOR CENTRAL AND
SOUTHERN VALLEY-DANIELS-SHERIDAN-WESTERN ROOSEVELT-GARFIELD-
MCCONE-NORTHERN VALLEY.
WINTER WEATHER ADVISORY UNTIL 5 PM MST SATURDAY FOR RICHLAND-
DAWSON-PRAIRIE-EASTERN ROOSEVELT.
WINTER STORM WARNING UNTIL 5 PM MST SATURDAY FOR WIBAUX.
&&
$$
WEATHER.GOV/GLASGOW
