Area Forecast Discussion
Issued by NWS Gaylord, MI

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FXUS63 KAPX 200213
AFDAPX

Area Forecast Discussion
National Weather Service Gaylord MI
1013 PM EDT Tue Mar 19 2019

.UPDATE...
Issued at 1013 PM EDT Tue Mar 19 2019

High pressure center continues to push eastward away from Michigan
late this evening...as two low pressure system begin to approach
our state. A northern stream system is moving out of Central
Canada and into the far NW Great Lakes region attm...while a
southern stream system is moving out of the Central Plains toward
the Mid Mississippi Valley. These two systems will phase over
Michigan by Wednesday afternoon...producing widespread precip for
our area thru Wednesday evening.

In the meantime...clouds will continue to steadily increase
overnight across our entire CWA in advance of these merging
systems...with chances of light snow increasing across Eastern
Upper Michigan very late tonight. Still expect precip will become
widespread across our entire CWA on Wednesday...with a mix of rain
and snow expected but little in the way of snow accumulation.

&&

.NEAR TERM...(Through Tonight)
Issued at 340 PM EDT Tue Mar 19 2019

...Clouding up from north to south...

High impact weather potential...none.

High pressure sits off the mid-Atlantic coast, while low pressure is
digging into far nw Ontario. That low (at 1009mb) will approach the
northern tip of Lk Superior by morning. Associated cloud cover will
expand southward into northern MI tonight, though it is considerably
less certain that precip will make it here before 8 am.

Pleasant late-winter/early spring day out there, with a burgeoning
cu field over n central/ne lower MI, some standing-wave mid clouds
over upper MI, and patchy/thin cirrus over top of all that. Thicker
cloud cover was noted just north of Superior. The cu will dissipate
with loss of diurnal heating this evening. Those thicker clouds
upstream will start to push into eastern upper MI after 9-10pm, far
northern lower MI toward midnight, and the rest of the area
overnight. Increasing low- and mid-level isentropic ascent/theta-e
advection (primarily at and below 700mb) in the warm sector of the
approaching clipper is the primary forcing mechanism. This forcing
is broad but not strong, and in the low levels we are lifting
initially dry air. We start to approach deeper saturation in
eastern upper MI after 5-6am. This is generally a little
slower/drier than the going forecast, and the new forecast follows
that trend, bringing a chance of snow to eastern upper MI very
very late tonight. Better pops will await the arrival of a sharper
forcing mechanism, which occurs later on Wednesday.

Definitely an opportunity for some radiative cooling in northern
lower MI before we cloud up. On the other hand, the pressure
gradient is tightening, and our starting point this afternoon is
relatively warm. Will still go a bit below guidance in n central and
ne lower MI. But that still keeps min temps mild, mid 20s to
lower 30s.

&&

.SHORT TERM...(Wednesday through Friday)
Issued at 340 PM EDT Tue Mar 19 2019

...Mild temperatures early then colder Friday, seasonal late winter
precipitation...

High Impact Weather Potential: Minor, with slowly warming
temperatures Wednesday and wintry pcpn making for some possible
slippery roads early, with a period of freezing drizzle possible
early Thursday.

Primary Forecast Concerns/Challenges: Precipitation type and chances
through the period.

Pattern Synopsis/Forecast...There will be several chances for pcpn
across the northern Great Lakes through the forecast period as a
couple of features drop south across the Great Lakes through Friday.
Additionally, an upper trough and slightly cooler temperatures will
develop over the nrn Lakes Wednesday and Thursday, before a sharper
trough colder mid lvl temperatures dig into the Great Lakes Friday.

Precipitation chances increase rapidly across northern Michigan
Wednesday as a sfc and upper level trough drop south across Lake
Superior. Mid lvl qvectors (850/500mb) shows strong convergence
developing across nrn Michigan through early Wednesday with forcing
diminishing greatly during the evening as the clipper slowly pushes
east. Model soundings showing significant mstr through the column
for widespread pcpn across the entire forecast Wednesday. Pcpn type
will be a little difficult as model soudnings show freezing lvls
bouncing around 700ft north which would suggest a wintry mix into
the evening for east Upper and Tip of the Mitt. Model soundings show
freezing lvls around 2100ft over the srn cwa thru Wed aftn, before
dropping quickly below 500ft during the evening, suggesting a rain
event through the afternoon for the srn forecast area before
transitioning to a wintry mix in the evening.

There is still some minor concern for patchy freezing drizzle over a
portion of nrn Michigan early Thursday as model soundings show
drying in mid and upper lvls while abundant mstr lingers trapped in
low lvls. Some light pcpn is then expected late Thursday afternoon
as a weak boundary drops quickly over the state. Some minor lake
induced snows are possible in favored northernly flow snow belts
Thursday night as sfc-850mb winds trend n/nw and mid lvl temps drop
to -12c on the backside of an exiting clipper. Overall Friday looks
dry and colder (afternoon temps in the 30s) with model soundings
showing extremely limited mstr through much of the column while
850mb temps fall to near -14c.

.LONG TERM...(Friday night through Tuesday)
Issued at 340 PM EDT Tue Mar 19 2019

Widely varying temperatures with limited chances for precipitation
through the period. The Great Lakes and upper Midwest will be
largely dominated by high pressure during the forecast period which
will limit pcpn chances into the beginning of next week. However,
there is a small chance for pcpn Sunday night, the result of a weak
boundary dropping south over the state. Mild temperatures are
expected through the weekend due to weak upper ridging, with a
return to colder temperatures early next week as mid lvl temps fall
back to -12c in developing upper trough.

&&

.AVIATION...(For the 00Z TAFS through 00Z Wednesday evening)
Issued at 713 PM EDT Tue Mar 19 2019

Two low pressure systems will approach Michigan tonight...one from
Central Canada and one from the Central Plains. These two system
will phase over Michigan by Wednesday afternoon...resulting in the
production of widespread precip across our area beginning very
late tonight and continuing thru Wednesday evening. The precip
will begin as a mix of rain and snow in the morning...and then
switch over to mainly rain by afternoon. LLWS will develop late
tonight into Wednesday morning as low level winds strengthen ahead
of this system.

&&

.MARINE...
Issued at 340 PM EDT Tue Mar 19 2019

Low pressure nearing far nw Ontario is diving southward, and will
approach Lake Superior Wed morning. Sw winds will increase ahead
of the low. Wind gusts will approach advisory levels in spots, but
waves will more definitely get there, mainly from Leland
southward. Advisories will be posted there late tonight and much
of Wednesday.

&&

.APX WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
LH...NONE.
LM...SMALL CRAFT ADVISORY until 4 PM EDT Wednesday for LMZ344>346.
LS...NONE.
&&

$$

UPDATE...MR
NEAR TERM...JZ
SHORT TERM...SR
LONG TERM...SR
AVIATION...MR
MARINE...JZ



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