Special Weather Statement, NWS Northern Indiana

Area Forecast Discussion
National Weather Service Northern Indiana
107 PM EDT Thu Jul 15 2021

.SYNOPSIS...
Issued at 308 AM EDT Thu Jul 15 2021

Warm and humid air will continue to spread north today ahead of
an approaching cold front. Showers and thunderstorms will develop
and move into the area and become numerous at times through
Friday as upper level disturbances move across the area in the
vicinity of a front when the heaviest rainfall is expected.

&&

.UPDATE...
Issued at 1105 AM EDT Thu Jul 15 2021

Main near term forecast concern is timing and extent of stronger
convection this afternoon/evening.

Remnants from overnight convection across the MS River Valley have
stabilized low levels somewhat across northwest Indiana into
southern Lower Michigan where residual mid level clouds persist
this morning. Southeast of these mid clouds, temperatures have
shot up close to the 80 degree mark at 15Z with dew points into
the low 70s in spots. These residual clouds may have slightly
delayed onset of convection today, and have continued trend of
previous forecast in delaying increase in PoPs late this
morning/early this afternoon.

For this afternoon, differential heating and approach of surface
cold front will likely result in scattered thunderstorm
development by the 19Z-21Z timeframe. Preferred location will
likely be where differential heating forcing exists currently,
with additional aid to lift from approaching front. RAOB data this
morning upstream across DVN/ILX indicate some respectable
westerly low level wind profiles (35-40 knots at 1800 feet). More
robust instability axis may be somewhat narrow in focus this
afternoon where near 2 inch PWATS pool along and just in advance
of the frontal boundary. Combination of shear/instability along
this narrow corridor still appears to be support some strong/iso
severe potential late this afternoon into early this evening. Main
threats still appear to be localized stronger wind gusts and
localized heavy rainfall. Overall, previous forecast in good
shape, and just made minor downward adjustment to PoPs this
afternoon/early evening north of US Route 6 where instability may
be a bit more tempered.

&&

.SHORT TERM...(Today through Saturday)
Issued at 308 AM EDT Thu Jul 15 2021

At the onset, the first round of showers and storms associated
with an upper level disturbance was already moving east across
northeast IL. These storms were starting to become outflow
dominated and should weaken early this morning. Showers should
make into northwest areas before they intensify this afternoon and
become more widespread with daytime heating. Prefer a general
blend of a number of the CAMs and the spectral models that
continue to advertise a heavy rain event from this afternoon
through Friday night with 2 to 4 inches of rain possible in any of
the heavier bands. There was still some detail yet to be resolved
including where outflow boundaries will set up and when
convection will fire. There was increasing support for bands of
heavy rain to develop along an outflow boundary over northern
Indiana this afternoon. Precipitable water values should be close
to 2.0 inches during this period. There is also a marginal severe
weather threat which includes strong gusty winds today as
conditions destabilize with daytime heating. The GFS and others
support CAPE values reaching or close to 2000 J/Kg. Very low MBE
velocities indicate there is a good chance for back- building
cells, and hence the greater potential for flooding. For more
information about the short term discussion, please see the
Hydrology section below.

&&

.LONG TERM...(Saturday Night through Wednesday)
Issued at 308 AM EDT Thu Jul 15 2021

An upper level ridge will build north into the Central Plains
during the middle of next week. Hot temperatures are forecast into
this area. At this time, it looks the forecast area will be far
enough east in the vicinity of an upper level trof to escape the
heat with high temperatures staying close to normal from 80 to 85.

&&

.AVIATION...(For the 18Z TAFS through 18Z Friday Afternoon)
Issued at 106 PM EDT Thu Jul 15 2021

Main changes to 18Z TAFs will be for the initial 6 to 9 hour
period with the remainder of the period conditional on how the
initial convection sets up.

Vis sat showing 2 bands of enhanced cu with a few showers already
showing up between KVPZ and KRZL. Many of the high res models tend
to support that the bulk of the initial convection could form just
south of KSBN but it could be close. Was tempted to limit to VCTS
at KSBN, but will just move up timing to start at 18Z and limit
tempo to a few hours. Line of convection should evolve and move
towards KFWA with timing also moved up somewhat to address current
trends. Localized IFR/LIFR conditions could materialize briefly
with the strongest convection but is not captured prior to 00Z.

Several models suggest convection across N MO moves NE into the
area after 00Z with several rounds possibly continuing through the
remainder of the TAF period. The greatest threat will likely
reside at KFWA overnight into Fri AM but could very well edge back
NW into KSBN. Period after 3 or 4Z has been generally left alone
for now given the low confidence on exact setup and impacts of the
afternoon convection.

&&

.HYDROLOGY...
Issued at 308 AM EDT Thu Jul 15 2021

..Heavy rainfall may cause flooding through Saturday week...

Very moist air will spread over the area ahead of a cold front and
upper level systems today through Friday. Showers and thunderstorms
with heavy rain will move east today and should weaken this
morning. However, the storms should redevelop later today and
become widespread. The soils have become a little more saturated
over the past several days. A number of rivers have risen into
action stage. Runoff over most areas will initially be low, but
given a longer duration of this event with heavy rain, more rises
on rivers can be expected with some rivers likely flooding
especially some of the more flashier ones like North Manchester
and Spy Run. Urban areas and poor drainage basins have a greater
chance for flooding and flash flooding. At this time, the heaviest
rainfall is expected south of the Michigan line where widespread
2 to 3 inches are forecast to fall during a 60 hour window from
this morning to late Saturday afternoon. During this time, it is
possible for training of storms to bring excessive rainfall rates
and amounts with rainfall rates exceeding 5 inches an hour and
amounts in excess of 5 inches. WPC has upgraded their Excessive
Rainfall Outlook to a slight risk for Friday.

&&

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

UPDATE...Marsili
SYNOPSIS...Skipper
SHORT TERM...Skipper
LONG TERM...Skipper
AVIATION...Fisher
HYDROLOGY...Skipper

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Hazardous Weather Outlook
National Weather Service Northern Indiana
547 AM EDT Thu Jul 15 2021

INZ003>009-012>018-020-022>027-032>034-MIZ078>081-OHZ001-002-004-005-
015-016-024-025-161000-
La Porte-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-
547 AM EDT Thu Jul 15 2021 /447 AM CDT Thu Jul 15 2021/

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

.DAY ONE...Today and tonight.

Thunderstorms with strong gusty winds and heavy rainfall may bring
local flooding of urban and low-lying areas today and tonight.
Friday.

.DAYS TWO THROUGH SEVEN...Friday through Wednesday.

Thunderstorms with strong gusty winds and heavy rainfall may bring
local flooding of urban and low-lying areas Friday through Friday
night.

.SPOTTER INFORMATION STATEMENT...

Spotter activation is not expected at this time.

MIZ077-161000-
Berrien-
547 AM EDT Thu Jul 15 2021

This Hazardous Weather Outlook is for southwest Michigan.

.DAY ONE...Today and tonight.

Thunderstorms with strong gusty winds and heavy rainfall may bring
local flooding of urban and low-lying areas today and tonight.
Friday.

There is a moderate swim risk Thursday.

.DAYS TWO THROUGH SEVEN...Friday through Wednesday.

Thunderstorms with strong gusty winds and heavy rainfall may bring
local flooding of urban and low-lying areas Friday into early Friday
night.

.SPOTTER INFORMATION STATEMENT...

Spotter activation is not expected at this time.

LMZ043-046-161000-
New Buffalo MI to St Joseph MI-Michigan City IN to New Buffalo MI-
547 AM EDT Thu Jul 15 2021

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

.DAY ONE...Today and tonight.

Thunderstorms are likely today and tonight that will bring hazardous
conditions to small craft.

.DAYS TWO THROUGH SEVEN...Friday through Wednesday.

Thunderstorms with gusty winds are likely Friday that will bring
hazardous conditions to small craft.

Special Weather Statement
National Weather Service Northern Indiana
211 PM EDT Thu Jul 15 2021

INZ014>016-151845-
Kosciusko-Marshall-Fulton-
211 PM EDT Thu Jul 15 2021

...A STRONG THUNDERSTORM WILL AFFECT NORTHEASTERN FULTON...
SOUTHWESTERN KOSCIUSKO AND SOUTHERN MARSHALL COUNTIES...

At 210 PM EDT, a strong thunderstorm was located near Argos, or 10
miles south of Plymouth, moving east at 30 mph.

Wind gusts up to 50 mph and pea size hail are possible with this
storm.

Locations impacted include...
Argos, Mentone, Walnut, Tippecanoe, Etna Green, Burket, Hoffman Lake,
Atwood, Maxinkuckee, Palestine, Beaver Dam Lake, Old Tip Town,
Sevastopol, Tiosa, Beaver Dam and Talma.

Torrential rainfall is also occurring with this storm, and may cause
localized flooding. Do not drive your vehicle through flooded
roadways.

Frequent cloud to ground lightning is occurring with this storm.
Lightning can strike 10 miles away from a thunderstorm. Seek a safe
shelter inside a building or vehicle.

&&

LAT...LON 4118 8641 4123 8640 4130 8592 4106 8592
TIME...MOT...LOC 1810Z 272DEG 28KT 4120 8632

HAIL...0.25IN
WIND...50MPH

FISHER

Special Weather Statement
National Weather Service Northern Indiana
247 PM EDT Thu Jul 15 2021

OHZ002-005-151915-
Henry-Fulton-
247 PM EDT Thu Jul 15 2021

...A LINE OF STRONG THUNDERSTORMS WILL AFFECT NORTHWESTERN HENRY AND
SOUTHEASTERN FULTON COUNTIES...

At 247 PM EDT, radar indicated strong thunderstorms were located
along a line extending from near Archbold to Delta. Movement was east
at 40 mph.

Winds in excess of 40 mph and pea size hail are possible with these
storms.

Locations impacted include...
Swanton, Delta, Brailey and Gerald.

This includes Interstate 80 in Ohio between mile markers 46 and 48.

Torrential rainfall is also occurring with these storms, and may
cause localized flooding. Do not drive your vehicle through flooded
roadways.

Frequent cloud to ground lightning is occurring with this storm.
Lightning can strike 10 miles away from a thunderstorm. Seek a safe
shelter inside a building or vehicle.

&&

LAT...LON 4148 8390 4144 8434 4145 8434 4162 8388
      4149 8388
TIME...MOT...LOC 1847Z 258DEG 36KT 4146 8430 4158 8401

HAIL...0.25IN
WIND...40MPH

FISHER