Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Twin Cities/Chanhassen Minnesota
1148 am CST Tuesday Jan 27 2015
Short term...(today and tonight)
issued at 236 am CST Tuesday Jan 27 2015
Today and tonight will be rather quiet as a surface ridge slowly
passes across the area. Thanks in large part to extensive stratus
east of a line from Appleton to Redwood Falls and Albert Lea...
temperatures are mild this morning...ranging from the upper 20s in
western WI to the lower or middle 30s across southern Minnesota.
The ridge will inch eastward into WI and this stratus will lift
northeast as winds back southwest in the cloud bearing layer this
afternoon. Most locations should see sun at some point today.
The high temperature grid today was formulated by mixing the GFS
down from 925 mb. This seemed to capture the current thinking the
best and is at least a few degrees warmer from previous forecasts
and the 00z set of model solutions. Given the milder start
however...this isn't much of a stretch and in some places it may
still be too cool - especially across southwestern Minnesota where there will be
quite a bit of sun.
Middle level ridging will be building east tonight making for another
set of mild lows. Temperatures may hold steady in the 30s for the majority
of the area...especially to the west.
Long term...(wednesday through monday)
issued at 236 am CST Tuesday Jan 27 2015
Long term trends remain pretty much on track. Flow aloft does
trend toward amplification...but the deterministic models did
through a small wrench in the forecast for Saturday.
Initially...the short wave trough moves east across the region
later Wednesday and Wednesday night. Warm air loft works into the
southwest ahead of cold front and inverted trough which trail
south to surface low in Iowa by late Wednesday afternoon. Models
suggest fair amount of cloud cover developing out ahead of the
trough Wednesday morning. This may inhibit significant warming
into eastern Minnesota and western Wisconsin. Will continue the
upper 30s in east central Minnesota for now. 40s likely to the southwest
again before significant cloud cover moves in.
The upper trough drops southeast Wednesday night dragging the
surface cold front through the by Thursday morning. Forcing is
weak but profiles suggest there may be a mix potential of freezing
drizzle and snow with this trough. Will continue the chance
probability of precipitation...with the higher probability of precipitation locating in west central Wisconsin.
Amounts will remain light with weak forcing forecast.
The next system works east across the southwest Continental U.S. And lifts
moisture northeast into southern Minnesota as the northern stream trough
dives southeast over the northern plains. This split flow
scenario is a change from yesterdays long term models. This will
give a chance of snow to mainly the southern and eastern County Warning Area as he
Arctic boundary interacts with the southern stream moisture. This
cold air intrusion looks to be short lived with the coldest
period Sunday into Monday. However...with the flow amplified and
progressive...we could continue the cooler than normal trend well
into next week.
Aviation...(for the 18z tafs through 18z Wednesday afternoon)
issued at 1147 am CST Tuesday Jan 27 2015
Extensive stratus across the region is only showing minor signs
of diminishing in south central Minnesota. Some breaks may reach north
this afternoon toward kstc...but for the most part MVFR ceilings
will prevail at most of the tafs sites through the period. IFR
ceilings from krwf to kaxn should lift to low MVFR by this evening
but confidence is not high and of these areas do improve to low
MVFR...they may go back down under 010 late tonight along with
MVFR br developing.
Kmsp...backed away from any VFR ceilings until late in the night
when the low level flow becomes more SW allowing for clearing over
Iowa to reach in. The VFR trend doesn/T look like it will last long
Wednesday morning as low level moisture increases ahead of an
incoming low pressure system.
/Outlook for kmsp/
Wednesday night...MVFR. Chance -sn/fzdz wind east 5 knots becoming northwest 10 kts.
Thursday...chance MVFR/-sn. Wind northwest 10-20 knots.
Friday...VFR. Wind S 5 knots.