:: First Winter Storm for '07-'08 Season Approaches
The headlines have been splashed everywhere across the nation since about mid day yesterday when the 12, 16, and 18Z models started stacking on a solution for a very textbook storm setup. Winter storm forecasts, much like summer storm forecasts, need to have very specific origin and path characteristics to get our attention, and this one has it all. The path is always the trickiest part, and by path I mean the actual track of the center of the lowest pressure circulation. The vortex of the storm is the heart, pumping hot and cold, moist and dry, invariably into contrast and collision. This storm's track is progged curently to drop off the front range this evening and settle into the KS/NE plains before accelerating into IA as Saturday progresses. This morning's AFD from MPX tells of their thinking for now, and I will post it here. Long story short: Snow is coming to Lakeville, and lots of it. Plan on 6".
THE BIG CHANGE BEGINS TO HAPPEN EARLY SATURDAY MORNING...AS
RETURN FLOW PICKS UP RATHER QUICKLY ON THE BACKSIDE OF THE
DEPARTING HIGH...RESULTING IN A FAIRLY RAPID INCREASE IN
MOISTURE AND WARM ADVECTION...AS THE SURFACE LOW BEGINS TO MOVE
OUT OF THE ROCKIES. THE STRONG WARM ADVECTION IS REFLECTED IN THE
VERY STRONG ISENTROPICS IN ADVANCE OF THE SYSTEM...WHICH WILL
FUEL THE STORM. THE MODELS CONTINUE TO HAVE SUBTLE DIFFERENCES...
ESPECIALLY REGARDING THE PLACEMENT OF THE WARM NOSE. A MIX SEEMS
INEVITABLE ACROSS A GOOD PORTION OF THE FORECAST AREA...WITH
MOSTLY FREEZING RAIN ACROSS FAR SOUTHERN MINNESOTA /INTERSTATE 90
CORRIDOR/...AND SLEET SOUTH OF THE TWIN CITIES. LOCATIONS NORTH OF
THE TWIN CITIES...AND ACROSS WESTERN MINNESOTA...SHOULD SEE ALL
SNOW FROM THIS EVENT. UNFORTUNATELY...THE TWIN CITIES IS IN THAT
QUESTION MARK ZONE...WHERE...DEPENDING ON HOW FAR NORTH THE LOW
TRACKS...THERE MIGHT BE MORE SLEET THAN SNOW. AS A RESULT...WE
HAVE ADDED A MENTION OF SLEET ON SATURDAY EVENING TO THE AREA
INCLUDING THE TWIN CITIES. SIGNIFICANT SNOW TOTALS STILL LOOK
LIKELY...ESPECIALLY ACROSS NORTHERN SECTIONS OF THE FORECAST
AREA...WHERE CLOSE TO A FOOT AMOUNTS LOOK POSSIBLE. WITH SO MANY
QUESTION MARKS REMAINING...FEW CHANGES HAVE BEEN MADE TO THE GOING
WEATHER TYPE...QPF...OR SNOW AMOUNT FORECASTS...WHICH WERE LARGELY
SUFFICIENT TO ILLUSTRATE WHAT THE CURRENT MODEL DATA ARE SAYING.
THE MAIN TWEAKS WERE TO BRING THE MENTION OF MIXED PRECIP TYPES A
LITTLE FARTHER NORTH THAN WERE PREVIOUSLY THERE.