115
FXUS63 KMQT 161945
AFDMQT

Area Forecast Discussion
National Weather Service Marquette MI
345 PM EDT Thu May 16 2024

.KEY MESSAGES...

- Showers into the evening hours. A few rumbles of thunder possible.

- A slight ~30% chance for thunderstorms exists across the
  western UP Friday afternoon and evening then over the
  Keweenaw Friday night.

- A southerly breeze and very warm temps in the 70s and 80s
  Saturday ahead of a cold front that brings a higher ~50%
  chance for afternoon thunderstorms. The strongest storms may
  contain small hail.

- Elevated fire weather possible on Saturday then very dry with
  light winds on Sunday.

&&

.SHORT TERM /THROUGH TONIGHT/...
Issued at 340 PM EDT Thu May 16 2024

Water vapor imagery and RAP analysis show a well-defined shortwave
trof extending from southern Manitoba to the western Great Lakes. A
vort max is clearly evident over n central WI. After a bit of a
diminishing trend late morning, shra are expanding this aftn ahead
of this feature. There has been some thunder to the s of Upper MI
from the Green Bay area to portions of the Door Peninsula. Current
temps range from the Upper 60s in eastern Upper MI where there has
been some filtered sunshine thru high clouds to the upper 40s/lwr
50s F w where clouds and sct shra have kept temps down.

Vort max will swing ne across Upper MI during the late aftn and
evening, supporting shra in its vcnty and ahead of it. There is up
to 200-300j/kg of CAPE avbl for parcels lifted from above sfc based
stable layer. So, can`t rule out a few rumbles of thunder. The shra
will be more nmrs across the e half of Upper MI where low-level jet,
850mb theta-e advection and weak isentropic ascent will be focused.
Shra will end most areas by midnight. With light winds overnight and
low-level moisture from rainfall, some fog may develop. Expect lows
tonight to range thru the 40s F.

&&

.LONG TERM /FRIDAY THROUGH WEDNESDAY/...
Issued at 347 AM EDT Thu May 16 2024

As the low pressure lifts away into northern Ontario Friday, dry
conditions are expected to return to Upper Michigan until Saturday
afternoon/evening, when a cold front brings additional light rainfall
to the area. That being said, expect summer-like conditions this
weekend into early next week as high temperatures soar into the 70s
and 80s in the interior areas. Rainfall looks to return early next
week and looks to continue on and off until near the end of the
extended period. Additional forecast details follow below.

The last of the rain showers lifts away from the far east Friday
morning as the parent low continues into northern Ontario. As this
occurs, warm air advection begins to move in from the southwest with
time. With the clouds clearing out across the land throughout the
daylight hours, we could see some steep lapse rates develop in the
lowest levels of the atmosphere, causing high temperatures to soar
into the 70s across the interior areas and the 60s along the Great
Lakes. In addition, the strong lapse rates may be enough to create
some pop-up showers across the interior west late in the afternoon,
as seen in some of the CAMs. However, I have my doubts on the shower
occurrence Friday afternoon as most of the atmospheric profile is
looking dry, particularly from the surface to the boundary layer as
an inverted-v around 5 kft high takes shape (according to CAMs
soundings). While a secondary shortwave over northern Minnesota
looks to bring rainfall near the Duluth area Friday afternoon and
evening, the moisture needed to sustain any real convection over the
west is too far away to be of any help. Therefore, I`ve limited
rainfall chances over the west to 10% or less Friday afternoon.

As weak ridging rides through the Great Lakes region Friday night
into Saturday, expect dry conditions over the U.P. Friday into
Saturday morning at the very least. While mostly clear skies will
allow radiative cooling across the area, with warm air advection
continuing across the area, temperatures may have a harder time
tanking than if the warm air advection wasn`t occurring.
Nevertheless, I`ve lowered the temperatures a few degrees using a
blend of the NBM10th and NBM, keeping the lows in the low 50s to
upper 40s in the west and mid 40s in the east. Moving into Saturday,
the dry conditions continue through to the early afternoon hours. As
southerly winds pick up, expect the downslope areas near Lake
Superior to get unseasonably warm; thinking that areas along the
Lake Superior shoreline could get into the 80s for a high, with many
areas in the interior west possibly getting into the mid 80s; this,
combined with the antecedent dry conditions and sunny skies could
bring some limited elevated fire weather concerns back across the
area Saturday afternoon, particularly along the downslope areas
near Lake Superior. With winds coming off of Lake Michigan, the
coolest (and most moist) area looks to be along its lakeshore from
Escanaba all the way east of Manistique to even the Bridge; expect
highs to only get into the upper 60s in this area. Once we hit the
mid to late afternoon, rain showers and possibly (30% chance) a few
embedded thunderstorms begin to make their way into the western
U.P.. However, with the daylight ending and the parent shortwave low
causing the convection moving towards Hudson Bay, shower activity
diminishes, with thunder chances looking to altogether vanish by
late in the night as the cold front continues across the rest of the
U.P. from west to east.

More weak high pressure ridging looks to cross the Upper Great Lakes
Sunday as warm air advection once again returns to the area thanks
to a troughing pattern moving from the western U.S. into the central
U.S.. Thus, expect a pretty similar setup to what we see Saturday,
albeit temperatures inland might be a couple of degrees lower and
the lakeshores noticeably cooler as the surface flow will probably
be weak enough to allow the lake breezes to get going. We may see
another limited elevated fire weather day in the interior west
Sunday as min RHs could drop into the mid 20 percents. Precipitation
returns late Sunday night/Monday as the first of multiple shortwaves
moves into our area.

Multiple shortwaves encroach on our neck of the woods early next
week as the troughing pattern moving from the central U.S. eastwards
keeps sending shortwaves from the Southern Plains up our way. This
will allow us to receive multiple shots of rainfall throughout the
latter portion of the extended period; we could see a soaking
rainfall from one of the shortwaves should "the cards fall right" so
to speak. However, given the high uncertainty of the forecast, the
probability of this happening is rather low at this time. As the
troughing pattern slowly trudges eastward, expect the temperatures
from Monday through next Thursday to progressively lower each day,
being above normal on Monday to below normal by Thursday. Once the
trough moves through, high pressure ridging moves back over us late
next week.

&&

.AVIATION /18Z TAFS THROUGH 18Z FRIDAY/...
Issued at 127 PM EDT Thu May 16 2024

A disturbance passing over the Upper Great Lakes will continue to
spread -shra across Upper MI this aftn/evening. As low-level
moisture increases, cigs will fall as well. At IWD, a few -shra
remain possible into the evening. Otherwise, expect mostly low MVFR
cigs thru this evening with some periods of IFR possible, especially
early this evening. Expect improvement to VFR at IWD overnight as
drying occurs under a shift to w to sw winds. At CMX, -shra have
already started, and cigs will fall thru MVFR for the rest of the
aftn. IFR cigs will develop this evening, if not sooner. As winds
switch from upslope ese to upslope westerly, will likely see
conditions fall to LIFR overnight as low clouds/some fog should
develop over western Lake Superior this aftn/evening. Expect
improvement to VFR at CMX around mid morning on Fri as daytime
heating mixes out moisture. At SAW, VFR will fall to MVFR by
late aftn, then to LIFR by late evening under upslope southerly
winds. A wind shift should bring slight improvement to IFR late
tonight. Expect improvement to VFR at SAW around mid morning on
Fri as daytime heating mixes out moisture.

&&

.MARINE...
Issued at 347 AM EDT Thu May 16 2024

Light winds of generally 20 knots or less continue today through
this weekend into early next week as a cold front brings some
showers and maybe (15% chance) an embedded thunderstorm or two this
evening through tonight. Thunder chances return Friday night over
the far western lake near Duluth as a low lifts through northern
Minnesota. As the cold front of the low moves eastward Saturday and
Saturday night, expect the shower and thunderstorm chances to travel
east with it, with the chances decreasing with time after the sun
sets. Thunder and shower chances return Monday as the first of
multiple shortwave lows move across the Upper Great Lakes region.

&&

.MQT WATCHES/WARNINGS/ADVISORIES...
Upper Michigan...
None.
Lake Superior...
None.
Lake Michigan...
None.

&&

$$

SHORT TERM...Rolfson
LONG TERM...TAP
AVIATION...Rolfson
MARINE...TAP