Special Marine Warning 2, NWS Northern Indiana

Area Forecast Discussion
National Weather Service Northern Indiana
125 AM EDT Fri Jun 18 2021

.SYNOPSIS...
Issued at 248 PM EDT Thu Jun 17 2021

A frontal system is expected to bring a threat for heavy
rain and strong to severe storms to parts of the area from late
tonight into Friday night. The passage of another cold front early
next week will bring additional chances for showers and
thunderstorms by that time.

&&

.SHORT TERM...(This Evening through Friday Night)
Issued at 248 PM EDT Thu Jun 17 2021

A strengthening low level jet extending from the Plains into the
Great Lakes region this evening should allow for thunderstorm
development over southeast Minnesota or western Wisconsin. Models
suggest this low level jet will sag southeast into the local area by
Friday morning. The warm advection within this jet should allow for
this convection to continue propagating southeast through the night,
reaching the northwest border zones during the pre dawn hours of
Friday.

There are some differences among the finer scale models as to how
far south this convection may get during the day on Friday, however
should see weakening after sunrise Friday as the low level jet
shifts off to the east. Regardless, very steep mid level lapse
rates should nose into the area late tonight from the west. This,
combined with adequate deep layer shear would suggest the
potential for strong to severe storms from the pre dawn hours of
Friday into the daytime hours.

Questions also revolve around additional convective development
later in the day Friday, and on into Friday night. This will
depend on how much convection affects the area late tonight into
Friday morning, which will ultimately determine the location of
the outflow boundary/instability gradient later in the day. At
this time, the models are suggesting redevelopment will be
possible by mid to late Friday afternoon over the southern zones,
or possibly south of the forecast area.

Steep mid level lapse rates, adequate deep layer shear, and high
precipitable waters suggest the potential for strong to severe
storms, along with heavy rainfall, will remain possible with any
convection into Friday night.

Based on above, plan on bringing PoPs in from the northwest late
this evening, and spreading them across the remainder of the
forecast area by Friday morning. Will keep PoPs the highest over the
southern zones later in the day Friday and Friday night, closest to
the expected zone of redevelopment.

&&

.LONG TERM...(Saturday through Thursday)
Issued at 248 PM EDT Thu Jun 17 2021

Ensemble and operational model data suggest a diffuse frontal
boundary may linger near or over the southern zones on Saturday,
before washing out Saturday night or Sunday. Considering the
amount of convection expected during the short term, would think
the effective boundary/main instability gradient will end up
farther south by that time. Will keep some chance PoPs, mainly
over the southern zones, for Saturday and Saturday night, to allow
for any convection that may develop near the frontal zone.

Otherwise, ensemble data suggest a rather deep trough is expected to
move through the Great Lakes early next week. This trough looks to
be progressive at this time, with flat west northwest upper flow
returning by the end of the forecast period.

The associated surface front looks to pass through the forecast area
either late Sunday night, or during the day Monday. Will keep PoPs
going from Sunday through the early parts of Tuesday to cover the
passage of this front. At this point, it appears the highest PoPs
will be in the Sunday night into Monday period. Wind fields with
this system look fairly strong, but lapse rates don't look
particularly impressive at this point.

Will trend towards a dry forecast from later in the day Tuesday
through Wednesday, with surface high pressure moving through, and
rising heights aloft.

Some of the ensemble members indicate the potential for another
wave to move into the Midwest by next Thursday. Will add some
chance PoPs to the forecast at that time.

&&

.AVIATION...(For the 06Z TAFS through 06Z Friday Night)
Issued at 121 AM EDT Fri Jun 18 2021

The TAF starts with dry weather allowing for VFR conditions.
However, we'll be watching for some showers and thunderstorms to
come in from the northwest. Models have some sort of congruency
around bringing showers and storms in around 10z at SBN. Model
reflectivity seems to indicate that any thunderstorms will be in the
dying phase as they are entering. This would give greater
probability to a MVFR and VFR conditions as opposed to IFR
conditions. However, if we do get stronger storms to come in and
heavier rain, this would lean towards the IFR conditions especially
from lower visibility.

Have also added some gusty winds to 25kts with low level lapse
rates forming during the early afternoon. Some LLWS is possible
during the early morning hours, but it may not be strong enough to
really classified as LLWS.

Then we'll have a period during the later morning into the early
afternoon where the atmosphere will have an opportunity to recover.
If it can clear out any debris clouds and bring in more instability
and get the other ingredients to line up as some models indicate, we
may be able to get some stronger to severe thunderstorms in during
the afternoon and evening. Those storms have a better potential to
create IFR conditions should the debris clouds from the morning
convection clear out during the recovery period.

&&

.IWX WATCHES/WARNINGS/ADVISORIES...
IN...NONE.
MI...NONE.
OH...NONE.
LM...NONE.
&&

SYNOPSIS...JAS
SHORT TERM...JAS
LONG TERM...JAS
AVIATION...Roller

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Hazardous Weather Outlook
National Weather Service Northern Indiana
520 AM EDT Fri Jun 18 2021

INZ004>009-012>018-020-022>027-032>034-MIZ078>081-OHZ001-002-004-005-
015-016-024-025-190930-
St. Joseph IN-Elkhart-Lagrange-Steuben-Noble-De Kalb-Starke-Pulaski-
Marshall-Fulton IN-Kosciusko-Whitley-Allen IN-White-Cass IN-Miami-
Wabash-Huntington-Wells-Adams-Grant-Blackford-Jay-Cass MI-
St. Joseph MI-Branch-Hillsdale-Williams-Fulton OH-Defiance-Henry-
Paulding-Putnam-Van Wert-Allen OH-
520 AM EDT Fri Jun 18 2021 /420 AM CDT Fri Jun 18 2021/

This Hazardous Weather Outlook is for northern Indiana, southwest
Michigan and northwest Ohio.

.DAY ONE...Today and tonight.

Thunderstorms with brief heavy rain and gusty winds are possible this
morning. A second round of storms is expected later this afternoon.
Severe weather is possible with damaging winds and heavy rain being
the primary threats. The best chances for severe weather will be
south of Highway 24.

Heat index values near 100 are possible south of Highway 30.

.DAYS TWO THROUGH SEVEN...Saturday through Thursday.

A few strong storms are possible again Saturday and Sunday with
localized heavy rain and gusty winds.

.SPOTTER INFORMATION STATEMENT...

Spotter activation will likely be needed this afternoon.

INZ003-MIZ077-190930-
La Porte-Berrien-
520 AM EDT Fri Jun 18 2021 /420 AM CDT Fri Jun 18 2021/

This Hazardous Weather Outlook is for northern Indiana and
southwest Michigan.

.DAY ONE...Today and tonight.

Thunderstorms with brief heavy rain and gusty winds are possible this
morning. There is a low chance of thunderstorms during the afternoon.

There is a moderate risk of dangerous swimming conditions along Lake
Michigan.

.DAYS TWO THROUGH SEVEN...Saturday through Thursday.

A few strong storms are possible again Saturday and Sunday with
localized heavy rain and gusty winds.

There is a moderate risk of dangerous swimming conditions along Lake
Michigan Monday and Tuesday.

.SPOTTER INFORMATION STATEMENT...

Spotter activation is not expected at this time.

LMZ043-046-190930-
New Buffalo MI to St Joseph MI-Michigan City IN to New Buffalo MI-
520 AM EDT Fri Jun 18 2021

This Hazardous Weather Outlook is for the nearshore waters of
southeastern Lake Michigan.

.DAY ONE...Today and tonight.

Thunderstorms with strong gusty winds are expected today.

.DAYS TWO THROUGH SEVEN...Saturday through Thursday.

Additional thunderstorms with gusty winds are possible at times
through the weekend.

Special Weather Statement
National Weather Service Northern Indiana
500 AM EDT Fri Jun 18 2021

INZ013-015-020-022>027-032>034-182000-
Pulaski-Fulton IN-White-Cass IN-Miami-Wabash-Huntington-Wells-
Adams-Grant-Blackford-Jay-
Including the cities of Winamac, Francesville, Medaryville,
Rochester, Akron, Monticello, Monon, Brookston, Logansport,
Royal Center, Peru, Grissom AFB, Mexico, Wabash,
North Manchester, Huntington, Roanoke, Bluffton, Ossian, Decatur,
Berne, Marion, Gas City, Upland, Hartford City, Montpelier,
Portland, and Dunkirk
500 AM EDT Fri Jun 18 2021

...Heat Index Values Near 100 Degrees Today...

High temperatures will climb into the mid 90s this afternoon with
dew point temperatures around 70. The combination of heat and
humidity will make it feel like nearly 100 degrees this afternoon.

If you have outdoor activities planned for today, be sure to take
precautions to guard against heat related illness. Drink plenty
of water, wear light weight light colored clothing, and take
frequent breaks in an air conditioned environment when possible.