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000
FXUS63 KAPX 021515
AFDAPX

Area Forecast Discussion
National Weather Service Gaylord MI
1015 AM EST Tue Mar 2 2021

.UPDATE...
Issued at 1015 AM EST Tue Mar 2 2021

Morning Synopsis:  Split flow pattern across the CONUS with a
northern branch Alberta Clipper short wave trough sliding into
Manitoba and a southern branch short wave trough over Oklahoma/
Arkansas.  Strong low and mid level warm advection into the upper
Midwest/upper Great Lakes/northern Ontario with a bit of a Pacific
moisture feed...pretty impressive 850mb thermal gradient from the
Dakotas (+10C) to northern New England (-32C).  40-50kt 850mb jet
from Minnesota into Upper Michigan.  1029mb surface high centered
over Ohio/Indiana and a 998mb low over southern Manitoba associated
with the clipper short wave trough setting up south/ southwest
boundary layer flow into the upper Lakes for today.  Warm front
extends south from the clipper into Minnesota/eastern Iowa.
Combination of isentropic ascent and short wave trough moving toward
northwest Ontario per WV imagery pushing some high based radar
returns across Upper Michigan/Lake Superior...cloud bases are still
mostly above 6K feet.  12z APX sounding was quite dry in the 900-
750mb layer...and this dry layer extends upstream so despite warm
advection not generating much beyond mid clouds (288K condensation
pressure deficits near 200mb across Minnesota).

&&

.NEAR TERM...(Today through Tonight)
Issued at 230 AM EST Tue Mar 2 2021

...Gusty southwest winds bring moderating temperatures today...

High impact weather potential: More gales today, especially on Lake
Michigan.

Pattern synopsis/forecast:

Very progressive northern stream flow regime continues early this
morning. Shortwave trough responsible for the cold and windy
conditions yesterday now racing well off to our east, with building
mid level heights found across the western Great Lakes. Surface high
pressure centered south to north across the region, with just some
lingering very light lake effect snow showers and flurries rotating
off the big waters. Looking further upstream, shortwave trough
pivoting across the southern Canadian Rockies, with surface low
pressure running out ahead of it across Saskatchewan. Surface trough
extends south of this low into the northern Plains, with elevated
warm air advection developing across the western Great Lakes between
this trough and overhead high pressure.

Mid and upper level flow regime becomes more zonal with time today
across the northern Conus/southern Canada. Current southwest Canada
shortwave rotates rapidly east, reaching northern Lake Superior by
this evening. Gusty southwest winds between attendant surface low
and departing high pressure expected to bring a return to warmer
temperatures to our area today.

Primary forecast concerns/challenges:

Marine concerns and temperature/cloud trends. Will also need to
address potential for a little rain and snow to clip eastern upper
Michigan today.

Details:

Saskatchewan low pressure will move quickly east, crossing just
north of Lake Superior this evening, reaching southwest Quebec by
Wednesday morning. Continues to appear vast majority of associated
precipitation will remain off to our north. However, may see just
enough moistening of the column to produce a few very light
rain/snow showers across eastern upper Michigan today into this
evening. Guidance derived soundings support dry condtions and more
sunshine the further south one goes. Increasing pressure gradient
between departing high and that approaching surface low looks to
bring some gusty southwest winds today, with NAM bufkit momentum
transfer analysis supporting wind gusts exceeding 30 mph this
afternoon, with locally higher gusts possible, especially near Lake
Michigan. These increasingly gusty southwest winds will help
temperatures recover quickly, with afternoon readings back into the
middle and upper 30s. Weak cold front extending back west from
departing low expected to slowly drop south into the area tonight.
Very weak forcing and limited mid/upper level moisture supports dry
conditions prevailing, although will likely see some increasing
clouds as low level moisture does deepen some. A relatively mild
night, with lows by Wednesday morning ranging from the lower 20s
across eastern upper Michigan, to the middle 20s to around 30 for
northern lower.

&&

.SHORT TERM...(Wednesday through Thursday)
Issued at 230 AM EST Tue Mar 2 2021

...Will there be any Precipitation? Probably Not...

High Impact Weather Potential...Minimal.

Pattern Synopsis/Forecast and possible impacts...Wednesday looks
dry, as the upper ridge is over the region. However The sfc ridge
axis is to the west in the Upper Mississippi Valley. GFS and HiResW
models have some precipitation with a 500 mb shortwave and sfc
trough that is moving southeast, mainly through NE Lower. The ECMWF,
NAM, and SREF are all dry, and considering the probabilities from
the other models, decided to keep the precipitation out. That is
really the only threat in the short term. High pressure then works
into the forecast area and keeps things dry for Wednesday night and
Thursday. The 500 mb low to the east is trying to retrograde, but
not to the extent that the GFS was showing the last two days. Things
have tended toward the drier ECMWF idea of the last few days.

.LONG TERM...(Thursday night through Monday)
Issued at 230 AM EST Tue Mar 2 2021

High Impact Weather Potential...Minimal.

Extended (Friday through Monday)...Friday, the models are now in
better agreement with the chance for a back door cold front, and
hold it to the east now through Friday morning, and keeps the region
dry. Saturday, the 500 mb ridge begins to build into the region has
the 500 mb low to the grudgingly moves east, taking with it any of
the vort lobes rotating around it. Things look dry, although between
06z/Sun and 12z/Sun the GFS has moisture along a warm advection zone
out ahead of the 500 mb ridge. The ECMWF is much slower and drier
with this feature, so will leave the region dry since the chances
look low, even on the GFS. Sunday, we warm advect and the sky looks
to clear out. The issues come for Monday, as mentioned yesterday,
the GFS has a shortwave trough that moves through the Upper Great
Lakes, faster than the ECMWF idea and brings rain into the region
around 12z/Mon out by 00z/Tue. While the ECMWF has nothing through
12z/Tue as the same feature stays south of the forecast area. Will
continue with the NBM dry forecast.

&&

.AVIATION...(For the 12Z TAFS through 12Z Wednesday morning)
Issued at 649 AM EST Tue Mar 2 2021

Only issue for today will be increasingly gusty southwest surface
winds and the development of LLWS later in the day. Otherwise,
just some passing high and mid level clouds. Weak cold front sags
south into the area tonight, with increasing low level moisture
along this front perhaps bringing some late night MVFR overcast.


&&

.MARINE...
Issued at 230 AM EST Tue Mar 2 2021

Gusty southwest winds today into this evening will bring gales and
high end small craft advisory conditions to our nearshore waters
(most widespread gales across northern Lake Michigan). Winds
gradually subside tonight as a weak cold front drops into the area.
Northwest winds expected Wednesday, perhaps resulting in more small
craft advisory conditions on portions of northern Lake Huron.


&&

.APX WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
LH...GALE WARNING until 11 PM EST this evening for LHZ345.
     GALE WARNING until 11 PM EST this evening for LHZ349.
     SMALL CRAFT ADVISORY until 5 AM EST Wednesday for LHZ346>348.
LM...GALE WARNING until 11 PM EST this evening for LMZ323-341-342-
     344>346.
LS...NONE.
&&

$$

UPDATE...JPB
NEAR TERM...MB
SHORT TERM...JL
LONG TERM...JL
AVIATION...MB
MARINE...MB