Flash Flood Watch 2, NWS Chicago, IL

Boone County, IL, Cook County, IL, DeKalb County, IL, DuPage County, IL, Ford County, IL, Grundy County, IL, Iroquois County, IL, Kane County, IL, Kankakee County, IL, Kendall County, IL, Lake County, IL, LaSalle County, IL, Lee County, IL, Livingston County, IL, McHenry County, IL, Ogle County, IL, Will County, IL, Winnebago County, IL, Benton County, IN, Jasper County, IN, Lake County, IN, Newton County, IN, Porter County, IN

771 
WGUS63 KLOT 281642
FFALOT

Flood Watch
National Weather Service Chicago IL
1142 AM CDT Mon Jun 28 2021

ILZ003>006-008-010-011-290045-
/O.EXA.KLOT.FF.A.0002.000000T0000Z-210630T0000Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Winnebago-Boone-McHenry-Lake IL-Ogle-Lee-De Kalb-
Including the cities of Rockford, Buffalo Grove, Gurnee, Sycamore, 
Crystal Lake, Waukegan, Woodstock, Byron, Rochelle, Algonquin, 
Mundelein, Oregon, DeKalb, McHenry, Belvidere, and Dixon
1142 AM CDT Mon Jun 28 2021

...FLASH FLOOD WATCH IN EFFECT THROUGH TUESDAY EVENING...

The National Weather Service in Chicago has expanded the

* Flash Flood Watch to include portions of north central Illinois 
  and northeast Illinois, including the following areas, in north 
  central Illinois, Boone, De Kalb, Lee, Ogle and Winnebago. In 
  northeast Illinois, Lake IL and McHenry.

* Through Tuesday evening

* Waves of thunderstorms with torrential downpours will move through 
  northern Illinois today through Tuesday. With already wet soils, 
  additional rainfall may lead to flash flooding of ditches, farm 
  fields, and roadways.

* Flooding of ditches, farm fields, and roadways as well as rises in 
  creek and river levels possible. In urban areas, flooding of 
  basements is possible.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

A Flash Flood Watch means rapid-onset flooding is possible, but not 
yet certain, based upon the latest forecasts. Flash flooding is a 
dangerous situation. Persons with interests along area rivers, 
creeks, and other waterways should monitor the latest forecasts and 
be prepared to take action should flooding develop.

&&

$$

ILZ012-013-019>021-023-032-033-039-103>108-INZ001-002-010-011-019-
290045-
/O.CON.KLOT.FF.A.0002.000000T0000Z-210630T0000Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Kane-DuPage-La Salle-Kendall-Grundy-Kankakee-Livingston-Iroquois-
Ford-Northern Cook-Central Cook-Southern Cook-Northern Will-Southern
Will-Eastern Will-Lake IN-Porter-Newton-Jasper-Benton-
Including the cities of La Grange, Carol Stream, Gilman, Kentland, 
Calumet City, Chicago, Portage, Fowler, Wheaton, Evanston, 
Marseilles, Palatine, Beecher, Gibson City, Schaumburg, Downers 
Grove, La Salle, Bourbonnais, Chesterton, Merrillville, Northbrook, 
Lombard, Watseka, Pontiac, Roselawn, Mendota, Aurora, Hammond, 
Manhattan, Lemont, Streator, Oxford, Plano, Channahon, Cicero, Gary, 
Valparaiso, Bolingbrook, Kankakee, Wilmington, Minooka, Ottawa, 
Morocco, Morris, Oak Lawn, Rensselaer, Peotone, Joliet, Paxton, Oak 
Park, Dwight, Park Forest, Elgin, Des Plaines, Orland Park, Mokena, 
Oswego, Oak Forest, Plainfield, Yorkville, Bradley, Coal City, 
Crete, Fairbury, DeMotte, and Naperville
1142 AM CDT Mon Jun 28 2021 /1242 PM EDT Mon Jun 28 2021/

...FLASH FLOOD WATCH REMAINS IN EFFECT THROUGH TUESDAY EVENING...

The Flash Flood Watch continues for

* Portions of Illinois and northwest Indiana, including the 
  following areas, in Illinois, Central Cook, DuPage, Eastern Will, 
  Ford, Grundy, Iroquois, Kane, Kankakee, Kendall, La Salle, 
  Livingston, Northern Cook, Northern Will, Southern Cook and 
  Southern Will. In northwest Indiana, Benton, Jasper, Lake IN, 
  Newton and Porter.

* Through Tuesday evening

* Waves of thunderstorms with torrential downpours will move through 
  northern Illinois and northwestern Indiana today through Tuesday. 
  With already saturated soils, additional rainfall may lead to 
  flash flooding of ditches, farm fields, and roadways.

* Flooding of ditches, farm fields, and roadways as well as rises in 
  creek and river levels possible. In urban areas, flooding of 
  basements is possible.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

A Flash Flood Watch means rapid-onset flooding is possible, but not 
yet certain, based upon the latest forecasts. Flash flooding is a 
dangerous situation. Persons with interests along area rivers, 
creeks, and other waterways should monitor the latest forecasts and 
be prepared to take action should flooding develop.

&&

$$

MDB

434 
WGUS63 KLOT 282228
FFALOT

Flood Watch
National Weather Service Chicago IL
528 PM CDT Mon Jun 28 2021

ILZ003>006-008-010>013-019>021-023-032-033-039-103>108-INZ001-002-
010-011-019-290630-
/O.CON.KLOT.FF.A.0002.000000T0000Z-210630T0000Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Winnebago-Boone-McHenry-Lake IL-Ogle-Lee-De Kalb-Kane-DuPage-La
Salle-Kendall-Grundy-Kankakee-Livingston-Iroquois-Ford-Northern Cook-
Central Cook-Southern Cook-Northern Will-Southern Will-Eastern Will-
Lake IN-Porter-Newton-Jasper-Benton-
Including the cities of La Grange, Carol Stream, Gilman, Kentland, 
Calumet City, Chicago, Portage, Kankakee, Crystal Lake, Wheaton, 
Woodstock, Marseilles, Rochelle, Beecher, Gibson City, Dixon, 
Palatine, McHenry, Downers Grove, DeKalb, La Salle, Belvidere, 
Chesterton, Merrillville, Northbrook, Lombard, Watseka, Gurnee, 
Pontiac, Roselawn, Manhattan, Mendota, Aurora, Hammond, Waukegan, 
Oregon, Bourbonnais, Lemont, Streator, Oxford, Plano, Fowler, 
Channahon, Rockford, Plainfield, Buffalo Grove, Gary, Valparaiso, 
Bolingbrook, Sycamore, Wilmington, Minooka, Ottawa, Morocco, Morris, 
Algonquin, Rensselaer, Evanston, Mokena, Joliet, Paxton, Oak Park, 
Dwight, Cicero, Park Forest, Peotone, Elgin, Des Plaines, Orland 
Park, Oak Lawn, Oswego, Oak Forest, Byron, Yorkville, Bradley, 
Mundelein, Coal City, Crete, Fairbury, DeMotte, Naperville, and 
Schaumburg
528 PM CDT Mon Jun 28 2021 /628 PM EDT Mon Jun 28 2021/

...FLASH FLOOD WATCH REMAINS IN EFFECT THROUGH TUESDAY EVENING...

The Flash Flood Watch continues for

* Portions of Illinois and northwest Indiana, including the 
  following areas, in Illinois, Boone, Central Cook, De Kalb, 
  DuPage, Eastern Will, Ford, Grundy, Iroquois, Kane, Kankakee, 
  Kendall, La Salle, Lake IL, Lee, Livingston, McHenry, Northern 
  Cook, Northern Will, Ogle, Southern Cook, Southern Will and 
  Winnebago. In northwest Indiana, Benton, Jasper, Lake IN, Newton 
  and Porter.

* Through Tuesday evening

* Waves of thunderstorms with torrential downpours will move through 
  northern Illinois and northwestern Indiana through Tuesday. With 
  already saturated soils, additional rainfall may lead to flash 
  flooding of ditches, farm fields, and roadways.

* Flooding of ditches, farm fields, and roadways as well as rises in 
  creek and river levels possible. In urban areas, flooding of 
  basements is possible.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

A Flash Flood Watch means rapid-onset flooding is possible, but not 
yet certain, based upon the latest forecasts. Flash flooding is a 
dangerous situation. Persons with interests along area rivers, 
creeks, and other waterways should monitor the latest forecasts and 
be prepared to take action should flooding develop.

&&

$$

Birk

921 
WGUS63 KLOT 290829
FFALOT

Flood Watch
National Weather Service Chicago IL
329 AM CDT Tue Jun 29 2021

ILZ003>006-008-010>013-019>021-023-032-033-039-103>108-INZ001-002-
010-011-019-291630-
/O.CON.KLOT.FF.A.0002.000000T0000Z-210630T0000Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Winnebago-Boone-McHenry-Lake IL-Ogle-Lee-De Kalb-Kane-DuPage-La
Salle-Kendall-Grundy-Kankakee-Livingston-Iroquois-Ford-Northern Cook-
Central Cook-Southern Cook-Northern Will-Southern Will-Eastern Will-
Lake IN-Porter-Newton-Jasper-Benton-
Including the cities of La Grange, Carol Stream, Gilman, Kentland, 
Calumet City, Chicago, Portage, Kankakee, Crystal Lake, Wheaton, 
Woodstock, Marseilles, Rochelle, Beecher, Gibson City, Dixon, 
Palatine, McHenry, Downers Grove, DeKalb, La Salle, Belvidere, 
Chesterton, Merrillville, Northbrook, Lombard, Watseka, Gurnee, 
Pontiac, Roselawn, Manhattan, Mendota, Aurora, Hammond, Waukegan, 
Oregon, Bourbonnais, Lemont, Streator, Oxford, Plano, Fowler, 
Channahon, Rockford, Plainfield, Buffalo Grove, Gary, Valparaiso, 
Bolingbrook, Sycamore, Wilmington, Minooka, Ottawa, Morocco, Morris, 
Algonquin, Rensselaer, Evanston, Mokena, Joliet, Paxton, Oak Park, 
Dwight, Cicero, Park Forest, Peotone, Elgin, Des Plaines, Orland 
Park, Oak Lawn, Oswego, Oak Forest, Byron, Yorkville, Bradley, 
Mundelein, Coal City, Crete, Fairbury, DeMotte, Naperville, and 
Schaumburg
329 AM CDT Tue Jun 29 2021 /429 AM EDT Tue Jun 29 2021/

...FLASH FLOOD WATCH REMAINS IN EFFECT THROUGH THIS EVENING...

The Flash Flood Watch continues for

* Portions of Illinois and northwest Indiana, including the 
  following areas, in Illinois, Boone, Central Cook, De Kalb, 
  DuPage, Eastern Will, Ford, Grundy, Iroquois, Kane, Kankakee, 
  Kendall, La Salle, Lake IL, Lee, Livingston, McHenry, Northern 
  Cook, Northern Will, Ogle, Southern Cook, Southern Will and 
  Winnebago. In northwest Indiana, Benton, Jasper, Lake IN, Newton 
  and Porter.

* Through this evening

* Waves of thunderstorms with torrential downpours will move through 
  northern Illinois and northwestern Indiana through Tuesday. With 
  already saturated soils, additional rainfall may lead to flash 
  flooding of ditches, farm fields, and roadways.

* Flooding of ditches, farm fields, and roadways as well as rises in 
  creek and river levels possible. In urban areas, flooding of 
  basements is possible.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

A Flash Flood Watch means rapid-onset flooding is possible, but not 
yet certain, based upon the latest forecasts. Flash flooding is a 
dangerous situation. Persons with interests along area rivers, 
creeks, and other waterways should monitor the latest forecasts and 
be prepared to take action should flooding develop.

&&

$$

Ratzer

627 
WGUS63 KLOT 291514
FFALOT

Flood Watch
National Weather Service Chicago IL
1014 AM CDT Tue Jun 29 2021

ILZ003>006-008-010>013-019>021-023-032-033-039-103>108-INZ001-002-
010-011-019-292315-
/O.CON.KLOT.FF.A.0002.000000T0000Z-210630T0000Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Winnebago-Boone-McHenry-Lake IL-Ogle-Lee-De Kalb-Kane-DuPage-La
Salle-Kendall-Grundy-Kankakee-Livingston-Iroquois-Ford-Northern Cook-
Central Cook-Southern Cook-Northern Will-Southern Will-Eastern Will-
Lake IN-Porter-Newton-Jasper-Benton-
Including the cities of La Grange, Carol Stream, Gilman, Kentland, 
Calumet City, Chicago, Portage, Kankakee, Crystal Lake, Wheaton, 
Woodstock, Marseilles, Rochelle, Beecher, Gibson City, Dixon, 
Palatine, McHenry, Downers Grove, DeKalb, La Salle, Belvidere, 
Chesterton, Merrillville, Northbrook, Lombard, Watseka, Gurnee, 
Pontiac, Roselawn, Manhattan, Mendota, Aurora, Hammond, Waukegan, 
Oregon, Bourbonnais, Lemont, Streator, Oxford, Plano, Fowler, 
Channahon, Rockford, Plainfield, Buffalo Grove, Gary, Valparaiso, 
Bolingbrook, Sycamore, Wilmington, Minooka, Ottawa, Morocco, Morris, 
Algonquin, Rensselaer, Evanston, Mokena, Joliet, Paxton, Oak Park, 
Dwight, Cicero, Park Forest, Peotone, Elgin, Des Plaines, Orland 
Park, Oak Lawn, Oswego, Oak Forest, Byron, Yorkville, Bradley, 
Mundelein, Coal City, Crete, Fairbury, DeMotte, Naperville, and 
Schaumburg
1014 AM CDT Tue Jun 29 2021 /1114 AM EDT Tue Jun 29 2021/

...FLASH FLOOD WATCH REMAINS IN EFFECT UNTIL 7 PM CDT/8 PM EDT/ THIS 
EVENING...

The Flash Flood Watch continues for

* Portions of Illinois and northwest Indiana, including the 
  following areas, in Illinois, Boone, Central Cook, De Kalb, 
  DuPage, Eastern Will, Ford, Grundy, Iroquois, Kane, Kankakee, 
  Kendall, La Salle, Lake IL, Lee, Livingston, McHenry, Northern 
  Cook, Northern Will, Ogle, Southern Cook, Southern Will and 
  Winnebago. In northwest Indiana, Benton, Jasper, Lake IN, Newton 
  and Porter.

* Until 7 PM CDT/8 PM EDT/ this evening

* Waves of thunderstorms with torrential downpours will continue to 
  move through northern Illinois and northwestern Indiana today. 
  With already saturated soils, additional rainfall may lead to 
  flash flooding of ditches, farm fields, and roadways.

* Flooding of ditches, farm fields, and roadways as well as rises in 
  creek and river levels possible. In urban areas, flooding of 
  basements is possible.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

A Flash Flood Watch means rapid-onset flooding is possible, but not 
yet certain, based upon the latest forecasts. Flash flooding is a 
dangerous situation. Persons with interests along area rivers, 
creeks, and other waterways should monitor the latest forecasts and 
be prepared to take action should flooding develop.

&&

$$

Birk

140 
WGUS63 KLOT 292106
FFALOT

Flood Watch
National Weather Service Chicago IL
406 PM CDT Tue Jun 29 2021

ILZ003>006-008-010>013-019>021-023-032-033-039-103>108-INZ001-002-
010-011-019-300000-
/O.CON.KLOT.FF.A.0002.000000T0000Z-210630T0000Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Winnebago-Boone-McHenry-Lake IL-Ogle-Lee-De Kalb-Kane-DuPage-La
Salle-Kendall-Grundy-Kankakee-Livingston-Iroquois-Ford-Northern Cook-
Central Cook-Southern Cook-Northern Will-Southern Will-Eastern Will-
Lake IN-Porter-Newton-Jasper-Benton-
Including the cities of La Grange, Carol Stream, Gilman, Kentland, 
Calumet City, Chicago, Portage, Kankakee, Crystal Lake, Wheaton, 
Woodstock, Marseilles, Rochelle, Beecher, Gibson City, Dixon, 
Palatine, McHenry, Downers Grove, DeKalb, La Salle, Belvidere, 
Chesterton, Merrillville, Northbrook, Lombard, Watseka, Gurnee, 
Pontiac, Roselawn, Manhattan, Mendota, Aurora, Hammond, Waukegan, 
Oregon, Bourbonnais, Lemont, Streator, Oxford, Plano, Fowler, 
Channahon, Rockford, Plainfield, Buffalo Grove, Gary, Valparaiso, 
Bolingbrook, Sycamore, Wilmington, Minooka, Ottawa, Morocco, Morris, 
Algonquin, Rensselaer, Evanston, Mokena, Joliet, Paxton, Oak Park, 
Dwight, Cicero, Park Forest, Peotone, Elgin, Des Plaines, Orland 
Park, Oak Lawn, Oswego, Oak Forest, Byron, Yorkville, Bradley, 
Mundelein, Coal City, Crete, Fairbury, DeMotte, Naperville, and 
Schaumburg
406 PM CDT Tue Jun 29 2021 /506 PM EDT Tue Jun 29 2021/

...FLASH FLOOD WATCH REMAINS IN EFFECT UNTIL 7 PM CDT/8 PM EDT/ THIS 
EVENING...

The Flash Flood Watch continues for

* Portions of Illinois and northwest Indiana, including the 
  following areas, in Illinois, Boone, Central Cook, De Kalb, 
  DuPage, Eastern Will, Ford, Grundy, Iroquois, Kane, Kankakee, 
  Kendall, La Salle, Lake IL, Lee, Livingston, McHenry, Northern 
  Cook, Northern Will, Ogle, Southern Cook, Southern Will and 
  Winnebago. In northwest Indiana, Benton, Jasper, Lake IN, Newton 
  and Porter.

* Until 7 PM CDT/8 PM EDT/ this evening

* Widely scattered clusters of thunderstorms with torrential 
  downpours will continue to move through parts of northern Illinois 
  and northwestern Indiana through early this evening. With already 
  saturated soils, additional rainfall may lead to flash flooding of 
  ditches, farm fields, and roadways.

* Flooding of ditches, farm fields, and roadways as well as rises in 
  creek and river levels possible. In urban areas, flooding of 
  basements is possible.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

A Flash Flood Watch means rapid-onset flooding is possible, but not 
yet certain, based upon the latest forecasts. Flash flooding is a 
dangerous situation. Persons with interests along area rivers, 
creeks, and other waterways should monitor the latest forecasts and 
be prepared to take action should flooding develop.

&&

$$

Birk

532 
WGUS63 KLOT 292352
FFALOT

Flood Watch
National Weather Service Chicago IL
652 PM CDT Tue Jun 29 2021

ILZ003>006-008-010>013-019>021-023-032-033-039-103>108-INZ001-002-
010-011-019-300100-
/O.EXP.KLOT.FF.A.0002.000000T0000Z-210630T0000Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Winnebago-Boone-McHenry-Lake IL-Ogle-Lee-De Kalb-Kane-DuPage-La
Salle-Kendall-Grundy-Kankakee-Livingston-Iroquois-Ford-Northern Cook-
Central Cook-Southern Cook-Northern Will-Southern Will-Eastern Will-
Lake IN-Porter-Newton-Jasper-Benton-
Including the cities of La Grange, Carol Stream, Gilman, Kentland, 
Calumet City, Chicago, Portage, Kankakee, Crystal Lake, Wheaton, 
Woodstock, Marseilles, Rochelle, Beecher, Gibson City, Dixon, 
Palatine, McHenry, Downers Grove, DeKalb, La Salle, Belvidere, 
Chesterton, Merrillville, Northbrook, Lombard, Watseka, Gurnee, 
Pontiac, Roselawn, Manhattan, Mendota, Aurora, Hammond, Waukegan, 
Oregon, Bourbonnais, Lemont, Streator, Oxford, Plano, Fowler, 
Channahon, Rockford, Plainfield, Buffalo Grove, Gary, Valparaiso, 
Bolingbrook, Sycamore, Wilmington, Minooka, Ottawa, Morocco, Morris, 
Algonquin, Rensselaer, Evanston, Mokena, Joliet, Paxton, Oak Park, 
Dwight, Cicero, Park Forest, Peotone, Elgin, Des Plaines, Orland 
Park, Oak Lawn, Oswego, Oak Forest, Byron, Yorkville, Bradley, 
Mundelein, Coal City, Crete, Fairbury, DeMotte, Naperville, and 
Schaumburg
652 PM CDT Tue Jun 29 2021 /752 PM EDT Tue Jun 29 2021/

...FLASH FLOOD WATCH WILL EXPIRE AT 7 PM CDT/8 PM EDT/ THIS 
EVENING...

The Flash Flood Watch for portions of Illinois and northwest Indiana 
will expire AT 7 PM CDT/8 PM EDT/ this evening.

Flooding is no longer expected to pose a threat. Please continue to 
heed remaining road closures. There is a chance for thunderstorms on 
Wednesday, especially south of Interstate 80. Locally heavy rainfall 
will be possible with any stronger storms.

$$

CMS

Area Forecast Discussion
National Weather Service Chicago/Romeoville, IL
215 AM CDT Mon Jun 28 2021

.SHORT TERM...
215 AM CDT

Through Tuesday...

Main Points:

- Scattered showers and thunderstorms may develop at any time
  today, though the highest coverage is expected during the
  afternoon and evening hours.

- The strongest storms today will produce torrential downpours
  with the threat for flooding of ditches, farm fields, and
  roadways. Winds strong enough to down tree limbs cannot be ruled
  out, either.

- A mostly dry night is expected tonight, with a repeat of
  performance of scattered showers and thunderstorms Tuesday
  afternoon.

Technical Discussion:

Currently, temperatures are in the upper 60s to around 70 with
overcast skies. A warm front is positioned over northern Illinois
with easterly winds and surface dew points in the 60s generally
along and north of Interstate 80 and southerly winds and dew
points in the lower 70s to the south. Scattered showers and a few
thunderstorms are ongoing at press time, and are being forced by a
modest low-level jet nosing into the warm front as well as modest
diffluence in the right entrance region of an upper-level jet. As
the warm front continues lifting northward this morning, widely
scattered showers and a few storms may "pop up" at any time given
weak capping and appreciable low-level moisture.

As a subtle wave lifts out of Missouri and surface temperatures
warm affording the development of some 1000-1500 J/kg of MLCAPE
this afternoon, an increase in thunderstorm coverage is
anticipated especially after 1 pm. Poor low- to mid-level lapse
rates of a mere 5.8 to 6 K/km will stunt the rate at which
thunderstorms grow today, though some 30-35 kt of 0-8 km shear
(thanks to a nearby upper-level jet) does suggest a multicell
cluster or even a weak supercell or two may materialize by mid-
afternoon. Accordingly, gusty winds strong enough to down tree
limbs cannot be ruled out with the strongest thunderstorms today.
The greater concern is for torrential downpours and associated
flooding of ditches, farm fields, and roadways. The 00Z HREF
24-hour LPMM QPF depicts the potential for localized 2-4"
rainfall totals today which would certainly lead to flooding if
the heaviest falls over the urban footprint of Chicago or any
area that has seen several inches of rain already in this wet
pattern. Expansive cloud cover today will limit highs to around
80.

At least modest suppression in the wake of the aforementioned
wave should provide a local minima in precipitation tonight
outside of a stray shower or two. Lows tonight should fall into
the upper 60s. With weak surface winds expected during the early
Tuesday morning hours, patches of ground fog may develop near
areas of recent rainfall. Tuesday will be similar to today with
highs near 80 and a flare in thunderstorm coverage during the
afternoon hours.

Borchardt

&&

.LONG TERM...
324 PM CDT

Tuesday through Sunday...

Forecast focus through the mid week period continues to be on a
continuation of our current wet pattern, with the potential for
additional periods of thunderstorms and locally heavy rainfall.
Latter half of the week and into the holiday weekend looks to be
cooler and potentially drier, though some spread remains in medium
range guidance with the eastward movement of an upper trough
across the Great Lakes region.

Upper level pattern characterized by anomalously strong upper
ridging across the Pacific Northwest/Canadian Rockies, a downstream
upper trough across the Plains and upper Midwest and upper ridging
from the mid-Atlantic eastward off of the east coast is expected to
remain in place through Wednesday. A plume of deep moisture with
PWATs near 2 inches will continue to extend from the western Gulf
into the Great Lakes, while a weak surface cold front lingers
across the area. This will continue to support the threat of
periodic clusters of heavy-rain producing thunderstorms Tuesday
into Tuesday evening-night. The WPC Day 3 ERO marginal/level 1
risk appears reasonable at this juncture, as well as likely PoPs.

Eventually, the east coast ridge is expected to weaken, allowing
the upper trough to begin to propagate eastward across the Great
Lakes region mid- week. This in turn allows weak surface low
pressure to move east of the region, and slowly drag the cold
front across the forecast area on Wednesday with a secondary front
on Thursday associated with stronger forcing from the digging
toward the central Great Lakes. Thunderstorm potential will
persist along and south of the front as it transits the area, but
should largely shift south of the forecast area as the front
clears the CWA Thursday.

For some detail on the Wednesday-Thursday period, Wednesday's
shower and t-storm trends will be modulated by the timing of and
how progressive the initial cold front is. Seeing a step down in
PWATs north of the frontal zone, so less moist air mass where this
occurs will yield less instability and probably a lower
convective coverage. While at the end of the NAM range and out of
its more reliable predictive scale, the 12z run shows essentially
the best case scenario for Wednesday with little/no convective
coverage in the entire CWA. Our PoPs focus the likely PoPs south
of I-80 as supported by the consensus of the remaining guidance,
with chance PoPs north.

Mid-level lapse rates are forecast to remain weak and mute
destabilization some, though deep layer shear could be marginally
supportive of storm organization if/where thunderstorms occur. At
this point if planning for outdoor activities, Wednesday is
trending more favorably than Tuesday, especially with northward
extent. An onshore wind shift from a bubble high moving over the
lake in the wake of the front will keep lakeside temps in the 70s
on Wednesday, while lower to perhaps mid 80s prevail inland. Then
on Thursday, since we won't lose the mid to upper 60s dew points
yet, plus a bit steeper mid-level lapse rates and seasonably brisk
mid-upper level flow with the trough (supportive deep layer
shear), there may be a risk for a few strong/severe storms during
the daytime amidst potential scattered convective coverage.

Ensemble guidance and the operational ECMWF has overall continued
with a more progressive eastward movement of the upper trough
across the Great Lakes region toward the end of the week, joined
by the 12z operational CMC. Some spread remains as noted in the
deterministic operational runs of the GFS and some of the ensemble
members of the foreign suites. These slower solutions would
support the lingering potential for mainly diurnal showers beneath
the upper trough, while the faster guidance would suggest a drier
trend heading into the weekend. In either case, north- northeast
low level flow should support cooler than average temps in the 70s
by Friday and Saturday along with lower humidity levels. Have
slight chance PoPs but no thunder mention given the majority of
the guidance supports a mainly dry and much less humid weekend.

As a final note, the northerly winds on Thursday-Friday in the
wake of the stronger secondary cold front could yield hazardous
swimming conditions at Lake Michigan beaches.

Castro/Ratzer

&&

.AVIATION...
For the 06Z TAFs...

Aviation Forecast Concerns:

* Spotty shower chances through the period, with timing of better
  SHRA/TSRA potential looking to be this afternoon and perhaps
  again toward sunrise Tuesday.

* MVFR ceiling development expected this morning, though smaller
  precipitation footprint lowers confidence in this somewhat.

* Modest east winds eventually turn southeast this afternoon and
  southerly later tonight.

Weak surface cold front which moved across the region Sunday as
stalled south of the terminals, and was roughly from KFSW to KIKK
and KGSH at 05Z. Southwest flow aloft will aid in lifting this
frontal boundary slowly back to the north later today and tonight.
This southwest flow will also maintain warm/moist advection atop
the frontal inversion, which will carry the threat of developing
scattered showers and thunderstorms especially with any enhanced
forcing provided by minor-amplitude short waves or convectively
generated vorticity maxima. Region radar mosaic across the Plains
and Midwest currently depicts one such disturbance lifting
northeast across central IL, with another noted further upstream
across eastern KS/far western MO. This first disturbance was
producing an area of SHRA/TSRA which will likely skirt south of
the terminals early this morning. Have carried a VC mention for
Chicago TAF sites after 07-08Z, with a tempo for SHRA only a KGYY.
Instability is generally limited to along/south of the front, and
thus TS will likely not impact KGYY directly. Other weaker SHRA
within a confluent zone from northern MO to northwest IL may
affect KRFD after 10Z or so. As instability develops northward
with the front later today, the disturbance emerging from the
KS/MO border area may have a better potential to produce TSRA into
northern IL mid-late afternoon, and have maintained a tempo TS for
that period. Beyond this afternoon, tonight looks relatively quiet
until another minor disturbance approaches toward Tuesday morning.

Model guidance continues to depict development of MVFR ceilings
across the terminals this morning. Where precipitation occurs this
is fairly likely, though with a smaller footprint to early morning
SHRA than previously expected, it's possible MVFR may be less
prevalent. will have to monitor cig trends over the next several
hours.

Wind wise, light east winds this morning will eventually turn more
southeast as the now-warm front approaches this afternoon. Winds
will eventually become south-southwesterly later tonight as the
front lifts north of the area. Of course, any TSRA this afternoon
could alter the wind field for a time.

Ratzer

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...None.
IN...None.
LM...None.
&&

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Hazardous Weather Outlook
National Weather Service Chicago/Romeoville IL
352 PM CDT Sun Jun 27 2021

ILZ003>006-008-010>013-019>021-023-032-033-039-103>108-INZ001-002-
010-011-019-282100-
Winnebago-Boone-McHenry-Lake IL-Ogle-Lee-De Kalb-Kane-DuPage-
La Salle-Kendall-Grundy-Kankakee-Livingston-Iroquois-Ford-
Northern Cook-Central Cook-Southern Cook-Northern Will-
Southern Will-Eastern Will-Lake IN-Porter-Newton-Jasper-Benton-
352 PM CDT Sun Jun 27 2021 /452 PM EDT Sun Jun 27 2021/

This Hazardous Weather Outlook is for portions of North Central
Illinois...Northeast Illinois and Northwest Indiana.

.DAY ONE...Tonight.

Weather hazards expected...

  Limited Thunderstorm Risk.
  Limited Flooding Risk, mainly south of a Pontiac to Valpo line.

DISCUSSION...

Scattered showers and a few thunderstorms producing heavy rain
could cause minor flooding into this evening, mainly south of a
Pontiac to Valparaiso line. Then toward daybreak Monday, the
coverage of heavy rain producing showers and thunderstorms is
forecast to increase from the west.

.DAYS TWO THROUGH SEVEN...Monday through Saturday.

Monday...
  Elevated Flooding Risk.
  Elevated Thunderstorm Risk.
Tuesday...
  Elevated Thunderstorm Risk.
  Limited Flooding Risk.
Wednesday and Thursday...
  Limited Thunderstorm Risk.
Thursday Night and Friday...
  High Swim Risk possible at Lake Michigan beaches.

DISCUSSION:

Additional clusters of heavy rain producing showers and
thunderstorms are expected on Monday and Tuesday, which could
cause pockets of flooding. Scattered thunderstorms are probable
on Wednesday and Thursday for portions of the area. While
widespread severe weather is not expected, a few strong to severe
thunderstorms can't be ruled out each day Monday through Thursday.

.SPOTTER INFORMATION STATEMENT...

  Spotter activation will not be necessary through tonight.

GENERAL STORM MOTION OF THE DAY:

  Moving toward the northeast at 30 mph.

LMZ740>745-282100-
Winthrop Harbor to Wilmette Harbor IL-
Wilmette Harbor to Northerly Island IL-
Northerly Island to Calumet Harbor IL-
Calumet Harbor IL to Gary IN-Gary to Burns Harbor IN-
Burns Harbor to Michigan City IN-
352 PM CDT Sun Jun 27 2021

This Hazardous Weather Outlook is for portions of the Illinois
nearshore waters of Lake Michigan and the Indiana nearshore
waters of Lake Michigan.

.DAY ONE...Tonight.

Weather hazards expected...

  Limited Thunderstorm Risk.

.DAYS TWO THROUGH SEVEN...Monday through Saturday.

Monday and Tuesday...
  Elevated Thunderstorm Risk.
Wednesday and Thursday...
  Limited Thunderstorm Risk.

Castro

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PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE CHICAGO IL
913 PM CDT SUN JUN 27 2021

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0129 PM     TORNADO          2 SSW DYER              41.47N 87.52W
06/26/2021                   LAKE               IN   NWS STORM SURVEY

            NWS STORM SURVEY FOUND DAMAGE CONSISTENT
            WITH AN EF-0 TORNADO WITH ESTIMATED PEAK
            WINDS SPEEDS OF 75 MPH FROM NEAR THE
            ILLINOIS/INDIANA STATE LINE IN DYER TO
            WESTERN PORTIONS OF SCHERERVILLE.

0206 PM     TORNADO          1 SSW CRETE             41.43N 87.65W
06/26/2021                   WILL               IL   NWS STORM SURVEY

            NWS STORM SURVEY FOUND DAMAGE CONSISTENT
            WITH AN EF-0 TORNADO WITH ESTIMATED PEAK
            WIND SPEEDS OF 70 MPH EXTENDING SOUTHWEST TO
            NORTHEAST WITHIN THE VILLAGE OF CRETE.

0436 PM     TORNADO          CHATSWORTH              40.75N 88.29W
06/26/2021                   LIVINGSTON         IL   NWS STORM SURVEY

            NWS STORM SURVEY FOUND DAMAGE CONSISTENT
            WITH A BRIEF EF-0 TORNADO WITH ESTIMATED
            PEAK WIND SPEEDS OF 85 MPH ON THE SOUTHEAST
            SIDE OF CHATSWORTH.

&&