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ARLINGTON HEIGHTS WEATHER

NWS Forecast for O'Hare International Airport Chicago, IL Last Update: 12:58 pm CDT Oct 11, 2024 - Elevated Fire Weather Risk Friday and Friday Night

Hazardous Weather Outlook (see below forecast)

Friday Afternoon:
Mostly sunny, with a high near 84. Southwest wind around 15 mph, with gusts as high as 25 mph.

Friday Night: Partly cloudy, with a low around 57. Southwest wind 5 to 15 mph becoming northeast after midnight. Winds could gust as high as 25 mph.

Saturday: A chance of showers between 1pm and 4pm, then a chance of showers and thunderstorms after 4pm. Mostly sunny, with a high near 66. Northeast wind 10 to 15 mph, with gusts as high as 20 mph. Chance of precipitation is 40%.

Saturday Night: A 40 percent chance of showers and thunderstorms before 1am. Mostly cloudy, with a low around 54. Northeast wind 5 to 15 mph, with gusts as high as 20 mph.

Sunday: Partly sunny, with a high near 65. Breezy, with a north wind 5 to 10 mph becoming northwest 15 to 20 mph in the afternoon. Winds could gust as high as 30 mph.

Sunday Night: Partly cloudy, with a low around 42. Breezy. Columbus Day: A 40 percent chance of showers after 1pm. Mostly sunny, with a high near 56.

Monday Night: A chance of showers. Partly cloudy, with a low around 38.

Tuesday: Sunny, with a high near 55.

Tuesday Night: Mostly clear, with a low around 38.

Wednesday: Sunny, with a high near 62.

Wednesday Night: Mostly clear, with a low around 43.

Thursday: Sunny, with a high near 68.

Hazardous Weather Outlook
National Weather Service Chicago/Romeoville IL
355 AM CDT Fri Oct 11 2024

ILZ003>006-008-010>013-019>021-023-032-033-039-103>108-INZ001-002-
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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-
355 AM CDT Fri Oct 11 2024 /455 AM EDT Fri Oct 11 2024/

This Hazardous Weather Outlook is for portions of north central
Illinois...northeast Illinois and northwest Indiana.

.DAY ONE...Today and Tonight.

Weather hazards expected...

  Elevated Fire Weather Risk.

DISCUSSION...

  Dry conditions and southwesterly wind gusts up to 25 to 30 mph
will result in an elevated risk for rapid spread of brush and
grass fires this afternoon.

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

Saturday...
  Limited Thunderstorm Risk.
Monday and Tuesday Nights...
  Elevated Frost Risk.

.SPOTTER INFORMATION STATEMENT...

  Spotter activation will not be necessary through tonight.



Area Forecast Discussion...CORRECTED
National Weather Service Chicago/Romeoville, IL
1249 PM CDT Fri Oct 11 2024

.KEY MESSAGES...

- Dry, breezy, and unseasonably warm today with an elevated   brush and grass fire risk.

- Scattered showers Saturday afternoon through early Sunday   morning.

- A notable cool-down early next week with the potential for   nightly frost and localized freeze conditions, along with lake   effect showers downwind of Lake Michigan.

&&

.DISCUSSION... Issued at 336 AM CDT Fri Oct 11 2024

Through Saturday Night:

Upper air analysis shows a mid level ridge currently extending over Illinois. With persistent southwesterly flow driving better warm air advection, afternoon temperatures are expected to reach into the low to mid 80s. These warmer temps will be accompanied by breezier southwesterly winds that could feature gusts between 25 to 30 mph. Dew points expected in the low to mid 40s will result in relative humidity values in the mid to upper 20 percent range creating an elevated risk for rapid spread of brush and grass fires.

Recent water vapor satellite imagery shows a southwest to northeast oriented cold front over northern Minnesota that is expected to dive southeastward over the area this evening. The main impacts just before midnight and through the overnight will be the winds increasing and sharply veering to the north- northeast, before becoming easterly Saturday mid-morning. The front will continue to sink southward before stalling out somewhere between I-88 and I-80 and turning into a quasi- stationary front Saturday afternoon. This stationary boundary is expected to create a robust afternoon temperature gradient with 60s to low 70s to the north and warmer 70s to even low 80s to the south.

As the front stalls, increased mid level moisture will move in from the west-northwest with a short wave trough passing aloft. Additionally, models are suggesting decent isentropic ascent along and ahead of the front will provide sufficient lift to support precipitation. With higher res models starting to key in on the amount of moisture available, PoPs were increased to the 40-60 percent range closer to Lake Michigan with the highest PoPs over northwest Indiana. Model soundings are also showing a narrow well of instability aloft Saturday late afternoon through the evening providing the chance for some elevated embedded thunder. As the next reinforcing cold front approaches on Sunday, chances for showers diminish by daybreak.

DK

Sunday through Thursday:

A notable pattern shift is anticipated for the start of the upcoming week as a vigorous upper level wave and closed upper low digs across the broader Great Lakes Region on Sunday. This in addition to a departing developing surface low will usher in a multi-day stretch of cold air advection into the local area.

The tightening pressure gradient associated with the aforementioned surface low will result in a period of gusty northwesterly winds up to 25 to 35 mph on Sunday, locally highest near the Indiana shore. After our extended stretch of above normal high temperatures, highs on Sunday will be near seasonable with much of the area mainly in the 60s. Expect any lingering showers from Saturday night to shift mainly east of the area by daybreak Sunday with the low, though can`t fully rule out a few lingering spotty showers.

This setup remains quite favorable for an extended period of lake effect showers over Lake Michigan Sunday night through Monday this colder airmass moves over a still warm Lake Michigan. The current wind orientation (NNW) favors the band of showers being mainly focused into northwest Indiana and southwest Michigan. However, there is a chance for scattered showers into Illinois late Monday as a trailing shortwave rounds the upper trough.

Monday and Tuesday will see the coldest temperatures so far this season for most of the area. In fact, there is the potential for sub-freezing temperatures for part of the area both Monday and Tuesday night (currently favoring northwest Illinois). High temperatures likely remain only in the 50s both days.

There remains a signal for a return to above normal temperatures toward the end of the week as narrow high amplitude ridging translates back over the region.

Petr

&&

.AVIATION /18Z TAFS THROUGH 00Z SUNDAY/... Issued at 1233 PM CDT Fri Oct 11 2024

Forecast concerns include...

Gusty southwest winds this afternoon. Wind shift to northeast late this evening. Gusty northeast winds overnight/Saturday morning.

Southwest winds will gust into the 20-25kt range through sunset and then are expected to diminish to 10kts or less and slowly turn more westerly through the evening. A cold front will move across the terminals mid/late this evening, shifting winds to the northeast. Only medium confidence on timing and trends will need to be monitored later this afternoon into this evening as the front approaches. Northeast winds will then continue for the rest of the period and will gust into the 20-25kt range with and after the front, but will slowly diminish through Saturday morning with gusts not expected Saturday afternoon.

There is a chance of showers by late Saturday afternoon and more likely Saturday evening and Saturday night, beyond the end of the new 30 hour ORD/MDW taf period thus no precip mention with this forecast. cms

&& 

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...None.
IN...None.
LM...Small Craft Advisory until 4 PM CDT Saturday for Winthrop
     Harbor to Wilmette Harbor IL.

     Small Craft Advisory from 10 PM this evening to 4 PM CDT
     Saturday for Wilmette Harbor to Calumet Harbor IL.

     Small Craft Advisory from midnight tonight to noon CDT
     Saturday for the IN nearshore waters.

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