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ARLINGTON HEIGHTS WEATHER

NWS Forecast for O'Hare International Airport Chicago, IL Last Update: 3:27 am CDT Oct 22, 2024

Hazardous Weather Outlook below forecast ...

Today: Isolated showers after 2pm. Partly sunny, with a high near 73. South wind 10 to 15 mph, with gusts as high as 30 mph. Chance of precipitation is 20%.

Tonight: Mostly clear, with a low around 55. South southwest wind 10 to 15 mph becoming west after midnight. Winds could gust as high as 20 mph.

Wednesday: Partly sunny, then gradually becoming sunny, with a high near 62. Northwest wind around 15 mph, with gusts as high as 25 mph.

Wednesday Night: Clear, with a low around 39. North northwest wind around 5 mph becoming calm after midnight. Winds could gust as high as 10 mph.

Thursday: Sunny, with a high near 64. Light southwest wind becoming south 5 to 10 mph in the morning. Winds could gust as high as 15 mph.

Thursday Night: A chance of showers before 10pm, then a chance of showers and thunderstorms between 10pm and 1am, then showers and possibly a thunderstorm after 1am. Low around 51. Chance of precipitation is 80%.

Friday: A 20 percent chance of showers and thunderstorms before 1pm. Partly sunny, with a high near 67.

Friday Night: Partly cloudy, with a low around 45.

Saturday: Sunny, with a high near 60.

Saturday Night: Partly cloudy, with a low around 41.

Sunday: Mostly sunny, with a high near 61.

Sunday Night: Mostly clear, with a low around 44.

Monday: Mostly sunny, with a high near 67.




 

Hazardous Weather Outlook
National Weather Service Chicago/Romeoville IL
350 AM CDT Tue Oct 22 2024

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- 350 AM CDT Tue Oct 22 2024 /450 AM EDT Tue Oct 22 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.   Limited Thunderstorm Risk.

DISCUSSION...

There is a low potential (<15%) for a lightning strike or two this afternoon among a chance for isolated showers, primarily west of the Fox Valley.

Additionally, an elevated risk for fire spread exists today across areas east of I-55. South winds will gust to 25 to 30 mph today, with occasional gusts as high as 35 mph possible during the afternoon, while midday RH values drop as low as the upper 20s to around 30%.

.DAYS TWO THROUGH SEVEN...Wednesday through Monday.

Thursday night...   Limited Thunderstorm Risk.

.SPOTTER INFORMATION STATEMENT...

  Spotter activation will not be necessary through tonight.

GENERAL STORM MOTION OF THE DAY:

  Moving toward the east at 30 mph.





Area Forecast Discussion
National Weather Service Chicago/Romeoville, IL
622 AM CDT Tue Oct 22 2024

.KEY MESSAGES...

- Continued mild today, followed by more seasonable conditions   for the rest of the week.

- A low potential for some light showers or a high-based thunderstorm this afternoon, especially west of the Chicago metro.

- An elevated risk for fire spread this afternoon mainly east of  I-55.

- Signal increasing for a decent shot at showers and embedded  storms Thursday night/Friday morning.

&&

.DISCUSSION... Issued at 315 AM CDT Tue Oct 22 2024

Through Wednesday:

Early this morning, we find an upper low spinning into the region from the central Plains. Stout forcing for ascent can be assumed along the leading edge of the vort where 500mb height falls are in the neighborhood of 90dam/12hr. It`s along this leading edge, over parts of IA and northern MO, where bands of showers and even a few embedded thunderstorms are present. This wave will continue propagating across the Midwest moving right overhead during the afternoon. As it approaches the area, the system will encounter drier low level air which should make it exceedingly difficult to produce precip altogether, but also for precip to survive its trip down to the surface. Forcing may also be degraded a bit by the time it gets here as the wave deamplifies some this morning. In fact, just in the past couple of hours, reflectivity and lightning trends out west are noticeably down. Guidance is in solid agreement that precip will continue trending down as the system works into northern IL. Most high res guidance hits the brakes on the more widespread QPF west of the area and paints streaky bands of light QPF into the CWA, especially the western CWA where modeled QPF is awfully scarce into the Chicago metro. With some noteworthy elevated instability at play given how cold conditions are aloft, any relatively deeper convective cores that go up could conceptually produce a clap of thunder or two, even in the absence of much precip. All of this is to say that rain coverage this afternoon should be rather isolated and a big majority of our CWA will likely be missing out on any rain today. The best chances exist the farther west you go where the seemingly better forcing and moisture/instability will be found.

Today`s storm system will also drive gusty southerly winds between 25 and 30 mph, possibly nearing 35 mph at times during the afternoon. High temperatures today are forecast in the lower and middle 70s with the warmest conditions south of I-80. Dewpoints down this way are forecast in the lower 40s for this afternoon yielding RHs in the upper 20s to around 30%. The drier air in conjunction with the gusty winds will present an elevated risk for fire spread today, mainly across areas east of about I-55.

Winds will subside some during the evening. A speedy low level jet looks to set up atop the diurnal inversion this evening with as much as 40 kt of flow being modeled at 925 mb. The time of day should help inhibit mixing much of that down to the surface, but winds may want to stay a bit breezy during the night. They will be quick to ramp back up in the wake of a cold front that will push across the CWA late tonight into early tomorrow morning. No rain is anticipated as this front passes through, but northwest winds are expected to already be gusting upwards of 20 to 30 mph by dawn tomorrow. This will continue through the morning before subsiding during the afternoon. The early morning cold front will limit high temperatures tomorrow to the lower and middle 60s.

-- Doom

 Wednesday Night through Monday:

Winds will ease through Wednesday evening with the arrival of the next surface high which will settle in directly overhead into Thursday morning. A renewed push of dry air and slackening winds will set the stage for areas of near-freezing temperatures into Thursday morning. Thursday should be a nice day as we`ll remain in between systems with shortwave ridging holding fast. Look for afternoon southerly breezes to return as the pressure gradient begins to tighten through the day.

For Thursday evening into Friday morning, attention will turn to a fast-moving, positively-tilted shortwave (currently embedded within a region of robust shear vorticity off the Pacific NW coast). At least modest cyclogenesis will result from the increased mass divergence aloft across South Dakota on Thursday, with the attendant surface low scooting east and gradually filling across Iowa and Illinois into Thursday night. Even with the weakening surface reflection, the low-level mass response is expected to be appreciable, with 50+ kt LLJ forecast to briefly impinge on parts of the forecast area. Increased static stability owing to the time of night with a good deal of decoupling noting in forecast soundings suggests any gust potential will be considerably muted.

The main impacts from this system will be from what look to be the best chances for rainfall we`ve had in a good while, including perhaps a few embedded thunderstorms. Given the positive tilt to the parent upper trough, a fast system motion will result in a somewhat limited residence time of deeper moisture in the region. Still, decent dynamics and at least some transient f-gen may help squeeze out some of the better rain totals we`ve seen in a while, although that`s not saying much, and signs continue to point towards precip amounts probably not making a huge dent in the ongoing drought conditions.

Things will begin to clear out through Friday afternoon and evening as the next surface high arrives. Conditions look tranquil and dry over the weekend with much more seasonable temperatures in the lower 60s. Return flow will commence on Monday as high pressure shifts across the northeast US. This will drive a return of afternoon breezes and a warming trend with the resumption of southerly flow.

During the Tuesday-Wednesday timeframe next week: while notable differences exist across the deterministic guidance suite, a trend in ensemble guidance is emerging featuring a robust storm system developing across the central CONUS. This signal is currently the most striking within the ECMWF/EPS, but also emerging in the GEFS, with ensemble meteograms/carpet maps depicting a notable uptick in wind gusts followed by at least some potential for showers/storms. We`ve seen these signals ebb and flow recently though, so hard to put too much stock in things at this range--just something to watch for now.

Carlaw

&&

.AVIATION /12Z TAFS THROUGH 18Z WEDNESDAY/... Issued at 621 AM CDT Tue Oct 22 2024

The main aviation weather concerns for the 12Z TAF period include:

* Gusty SSW winds today, followed by gusty NW winds on Wednesday

* A low potential for some showers and an isolated lightning   strike this afternoon

Near-southerly winds will remain below 10 kt into mid morning before gusts begin to build closer to mid-late morning. SSW winds are then expected to frequently gust into the 20 to 25 kt range from the late morning into early evening. A period of near 30 kt gusts may materialize during the afternoon. We`ll hang onto the SSW direction into Tuesday night as winds subside to mostly near or below 10 kt, with occasional gusts into the teens kt possible throughout the night. Nearing the predawn hours of Wednesday, a cold front passing through will veer winds to a NW direction. Winds should swiftly pick up behind this front with 20+ kt gusts expected in the couple of hours leading up to daybreak and continuing through the morning.

Additionally, a storm system will move across the region today presenting an opportunity for a few light showers this afternoon. At the moment, coverage is expected to be very isolated and any rainfall that does occur on the airfields will likely be rather brief. Chances are seemingly highest out near RFD. One or two rumbles of thunder are not out of the question thanks to some instability upstairs, however any heavy rainfall or widespread thunder coverage appear very unlikely. VFR conditions are expected throughout the period.

Doom

&&

.LOT WATCHES/WARNINGS/ADVISORIES... IL...None. IN...None. LM...Small Craft Advisory from 10 AM this morning to 7 PM CDT this      evening for the IL and IN nearshore waters.

     Small Craft Advisory from 3 AM to 3 PM CDT Wednesday for      Winthrop Harbor IL to Gary IN.

     Small Craft Advisory from 3 AM to 10 PM CDT Wednesday for Gary      to Burns Harbor IN-Burns Harbor to Michigan City IN.

&&

$$

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