Area Forecast Discussion Issued by NWS Duluth, MN
000
FXUS63 KDLH 111136
AFDDLH
Area Forecast Discussion
National Weather Service Duluth MN
636 AM CDT Thu Apr 11 2024
.KEY MESSAGES...
- A large, warm, and wet system is forecast to move through the
Upper Midwest Monday-Thursday of next week. Snow is possible
on the backside of this system.
- Slight cool down today and Friday, but still above average.
Warming back into the 60s this weekend into early next week.
- A clipper system on Saturday night brings a chance (20-40%)
for light rain. Thunderstorms are possible over northwest WI.
&&
.DISCUSSION...
Issued at 406 AM CDT Thu Apr 11 2024
Kind of a similar day today to yesterday though instability and
forcing is less/weaker while shear is higher in some locations.
This should lead to another round of afternoon showers with some
isolated thunderstorms especially closer to the larger shear
values in Lake and Cook counties where the sweet spot for weak
thunderstorms is maximized. We`re not working with much CAPE
(500 J/kg is the high end), but shear values peak near 40 kt
which isn`t too bad and occur in a local maxima of vorticity.
CAPE is still maximized in the hail growth zone, so peas look
like the best these puppies should be able to muster. Meanwhile,
similar conditions across NW WI with less shear, but more
affects from the larger system pinwheeling to our southeast with
about the same resultant conditions - showers with isolated
thunder.
In between systems until a clipper slides by on Saturday for
some small chances for meager light rain and largely non-
eventful weather.
The main focus of the forecast should be on the large system
that crosses Monday through Thursday. On Monday a LLJ, sneaks
into the area in concert with abundant shear, climatologically
high values of PWATs (1.2"), and a strong Fgen signal all
combining to usher in warm air and fairly steep lapse rates
giving a shot for thunderstorms and heavy rainfall. These
parameters further grow in magnitude as an expansive low
pressure spawns over the Great Plains and deepens to a sub-980
mb low somewhere over MN/WI. Strong jet dynamics and a
negatively tilted trough all play into this strongly forced
system which should provide large amounts of rain with periods
of thunderstorms. By Thursday, the system begins to exit, but
pulls down cold air and may produce accumulating snowfall though
it`s still a bit early with the specifics for this. Guidance
among model solutions begins to diverge with the handling of the
cold air timing on the systems exit. Overall, ensemble guidance
is fairly clustered lending higher confidence to the
deterministic solutions. Long story short, keep an eye on the
forecast as this system will likely bring some hazards to the
Northland. The drought conditions will help alleviate some of
the potential impacts of flooding from this system, but not
completely preclude them.
&&
.AVIATION /12Z TAFS THROUGH 12Z FRIDAY/...
Issued at 634 AM CDT Thu Apr 11 2024
VFR though local fog is occurring and should be brief. I think
it is done at the TAF sites despite a short residence. Shower
ceilings appear to be trending towards VFR this afternoon with
shower activity increasing after 19Z. Light winds will become
gusty from the north this afternoon. MVFR ceilings sail in
tonight.
&&
.MARINE...
Issued at 406 AM CDT Thu Apr 11 2024
Fairly calm until late this evening when conditions start to
become more hazardous with northwest winds gusting over 20 kts
with building waves along the South Shore. Wind gusts to 30
knots are possible along the North Shore Friday. Winds shift
northeasterly Saturday afternoon with hazardous conditions to
small craft becoming likely.
&&
.DLH WATCHES/WARNINGS/ADVISORIES...
MN...None.
WI...None.
MARINE...None.
&&
$$
DISCUSSION...Wolfe
AVIATION...Wolfe
MARINE...Wolfe