Scientific Forecaster Discussion
fxus63 kmpx 242117
Area forecast discussion
National Weather Service Twin Cities/Chanhassen Minnesota
417 PM CDT Sat Mar 24 2018
Short term...(this evening through sunday)
issued 355 PM CDT Sat Mar 24 2018
Main forecast concern is timing of next short wave trough
approaching the area later Sunday afternoon.
Water vapor imagery showing cirrostratus associated with outgoing
trough is finally thinning over the western County Warning Area. This trend is
expected to continue through the night with this systems exit.
Models suggesting clouds will be fast on the heals of this system,
with some weak forcing moving into far western County Warning Area late Sunday
afternoon. We should see increasing clouds from the west again
during the day. We kept the low end chance pop for some light rain
moving into the far west after 21z Sunday. Also, pressure
gradient increases during the day, especially to the west. We do
have a fresh snow pack to the south, and will likely affect lows
tonight and highs for Sunday. Those ares in deeper snow will see
temperatures remaining in the 30s with lower and mid 40s to the
east, where snow remains sparse.
Long term...(sunday night through saturday)
issued 355 PM CDT Sat Mar 24 2018
Couple of concerns develop into the longer term. Models trend
decent forcing ahead of the next trough later Sunday night and
Monday. The GFS is most impressive with its nearly coupled jet
structure as the system lifts into the area. The European model (ecmwf) is not
quite as developed but still manages to generate some mix
precipitation potential across the area. BUFKIT sounding showing
warm nose lifting into the region Monday into Tuesday. Although
ice aloft will likely be present with the passage of the trough,
we will see some melting occur as the precipitation develops.
Surface temepratures will be critical as to where rain/freezing
rain ill occur. At the moment, we have around one tenth of an inch
of freezing rain forecast over western portions of the cwa. We
will need to monitor boundary layer temperatures into future
forecasts. Also, accumulating snow potential arrives later Sunday
night and Monday, especially to the northwest as best
frontogenetic forcing and forcing along the better couple jet. We
presently have a general 2 to 4 inch snow accumulation across the
northern Minnesota portion of the cwa. Both forecast issues certainly
advisory potential. Stay tuned.
The flow aloft becomes a bit more progressive with both the GFS
and European model (ecmwf) bringing in the another short wave trough around Friday.
The GFS being a bit more amplified and stronger with its surface
low. Both will generate a fair amount of snow, especially across
the northern portion of the cwa, if they verify. Overall,
temperature trend is expected to remain below normal through the
Aviation...(for the 18z tafs through 18z Sunday afternoon)
issued at 1125 am CDT Sat Mar 24 2018
Snow dropped just south of the kmkt airfield this morning. Krwf is
about to end as well. Will bring up to VFR shortly with the rest
of the area seeing mix of mid/high level clouds into tonight. May
see some clouds move back in/develop later tonight ahead of the
next system, but feel all sites will remain VFR. East winds a bit
gusty at times this afternoon over the east, will become
southeast and increase into Sunday.
/Outlook for kmsp/
sun nite...VFR. Wind southeast 10-15 kts.
Monday...MVFR with chance -sn in the morning, then rain. Wind southeast 10 kts.
Tuesday...VFR with chance MVFR/-ra. Wind northwest 10 kts.