Scientific Forecaster Discussion
fxus63 kmkx 262128
Area forecast discussion
National Weather Service Milwaukee/Sullivan WI
328 PM CST sun Feb 26 2017
Tonight and Monday... forecast confidence is high.
Westerly winds will diminish this evening as weak high pressure
moves overhead. Clear skies will allow temps to fall into the lower
20s tonight. Dewpoints got up to the mid/upper 20s today, so there
is a risk of some patchy fog overnight.
Light southerly winds will keep temperatures mild on Monday, with
highs in the mid to upper 40s. Leaned toward higher side of guidance
for temps using bias-corrected MOS blend.
Monday night through Wednesday...forecast confidence...medium
Models are in decent agreement showing two weak mid level
shortwaves in the southwest flow Monday night and Tuesday, as one
jet Max pushes across the Great Lakes, while a second one is
associated with the advancing mid/upper trough that reaches the
upper Mississippi Valley. The European model (ecmwf) is a little slower and
stronger with the mid trough.
Should see some precipitation arrive by later Monday night ahead
of the low. Temperatures will be warming aloft and at the surface
as the precip moves in. Should see enough warming by the time the
precipitation arrives for rain. There is a little elevated Cape
Monday night that could bring a few thunderstorms with the
low/mid level warm air advection. Looks plenty mild enough by
daybreak Tue morning for all rain. Despite the clouds and rain,
it should be a mild day inland, as southeast low level flow ahead
of the low continues to draw up warmer temps.
Thunderstorm chances Tuesday depend on the model differences, and
would increase if the more northern track low of the GFS is
correct. However even the more southern track European model (ecmwf) brings the
low across the far southeast, and would result in a chance of
thunderstorms, since it is slower and stronger.
As the low strengthens to the east Wednesday, we may see
a rain/snow mix that may chance over to snow. The slower and
stronger European model (ecmwf) brings a little more snow potential towards
Wednesday afternoon. The new European model (ecmwf) would also extend the snow
chance into Wednesday evening.
Thursday through Saturday...forecast confidence...medium
Could see a little snow Thursday as a weak shortwave and
associated surface trough moves through. Looks like a dusting to
an inch, depending on the model.
Decent agreement among models for Friday, showing high pressure
and near normal temps to end the week.
GFS and dgex show a little light snow Friday night into Saturday
morning due to warm advection as the high departs. The European model (ecmwf) has
similar warming, though remains dry. Should see above normal high
temps per latest guidance, as temps aloft are expected to continue
warming through the day.
The zonal mid/upper flow becomes a little more southwest as a
shortwave exits the northern rockies. The European model (ecmwf) is a little faster
with this resulting in a little quicker return with milder air
ahead of a developing warm front across Iowa and northern
Winds will diminish quickly this evening. Light winds and lingering
low level moisture will give US a chance for at least patchy fog
overnight. If fog develops it will take until late morning for the
associated clouds to clear. Light southerly winds and a few mid
level clouds Monday afternoon will allow for mild temperatures once
Gusty southwesterly winds will quickly diminish this evening. Gusts
peaked early this afternoon and are coming down, so downgraded the
Gale Warning to a Small Craft Advisory. The advy GOES until 9 PM.
Plan on light southerly winds Monday, then easterly winds will build
higher waves on Tuesday. Winds and waves are expected to remain
below Small Craft Advisory levels.
Lm...Small Craft Advisory until 9 PM CST this evening for lmz643>646.