Marine Weather and Tide Forecast for Lake Petersburg, IL
May 18, 2024 11:36 PM CDT (04:36 UTC) Change Location
 | Sunrise 5:38 AM Sunset 8:11 PM Moonrise 3:37 PM Moonset 3:17 AM |
Area Discussion for - Central Illinois, IL
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FXUS63 KILX 190212 AFDILX
Area Forecast Discussion...Updated National Weather Service Lincoln IL 912 PM CDT Sat May 18 2024
KEY MESSAGES
- Above normal temperatures will continue through at least Tuesday, with highs in the upper 80s. Tuesday looks like the most humid day of the stretch, resulting in heat indices in the low 90s.
- Isolated storms are possible (20% chance) Sunday afternoon.
While much of the area will stay dry, locally heavy rainfall over 1.5" could occur beneath the storms that do develop.
- A stormy pattern will exist early next week, with potential for severe thunderstorms Monday through Wednesday. During that time frame, the greatest risk is for damaging winds west of I-55 Tuesday evening.
UPDATE
Issued at 912 PM CDT Sat May 18 2024
Skies are clear and winds are light southwest. Current forecast has a good handle on this with temps expected to drop into the middle 60s across the CWA Therefore, no official update is planned at this time.
Auten
DISCUSSION
Issued at 220 PM CDT Sat May 18 2024
For the rest of today, upper level height rises will continue to produce large-scale subsidence. While some areas of agitated Cu are evident on satellite, vertical development seems suppressed and I kept the forecast dry. A cold front is progressing across WI/IA this afternoon, although to this point, storm development has been confined to WI where there is better upper level forcing.
CAMs still show storms forming along the front in IA by late evening, but these quickly dissipate after sundown and are unlikely to reach the NW part of the ILX CWA
A summer-like pattern will exist through the middle of the upcoming work week, with above normal temperatures and storm chances, some of which could be severe. The Tues night-Wed timeframe understandably continues to be the main highlight, but there are other storm chances before then that also warrant discussion. High temperatures will be in the mid 80s to near 90F through Tues, while dewpoints will be in the mid 60s through Mon before climbing to near 70F on Tues. Due to those higher dewpoints, the highest heat indices are anticipated to occur on Tues, with values in the low to mid 90s.
** SUNDAY **
The chance for storms on Sunday is fairly low, as the area remains beneath an upper level ridge axis, but there are still a few potential mechanisms via which storms could form. The weak cold front NW of the area today is progged to move into the CWA late tonight and stall across the area on Sun. While upper support will not be conducive, forecast soundings do show an uncapped environment with moderate instability (2000-2500 J/kg of CAPE) and that front could provide sufficient lift to kick off storms. The latest CAMs suggest this scattered activity, if it were to develop, would occur between the IL River and I-70. Hodographs look crumpled (very weak shear), so similar to Friday I expect any storms to be relatively short-lived, but also slow-moving which could result in very isolated instances of heavy rainfall. HRRR 24-hour LPMM supports that assessment, with a few pockets where rainfall exceeds 1.5".
The other, lower confidence way that storms could impact the area on Sunday is via a convective complex that develops over the west- central Plains late tonight and rolls east across the Plains, potentially reaching west-central IL by Sun evening.
Latest CAMs are not as bullish on this idea compared to previous cycles, now showing the complex dissipating across IA as the nocturnal LLJ weakens and cloud-top warming occurs after sunrise.
Nevertheless, the instability gradient will be oriented such that if these storms hold together they would progress towards areas north of a Macomb- Bloomington line by Sun evening.
** MONDAY **
By 12z Mon, a shortwave and an associated weak sfc low are progged to be lifting towards the upper Midwest, located NW of the ILX CWA As this disturbance lifts north, there could be sufficient ascent to aid t-storm development late Monday morning through Monday evening in areas NW of the IL River. CAPE-Shear parameter space for that area appears marginally supportive of strong/severe storms, with moderate instability (again between 2000-2500 J/kg)
and marginal shear (25-30 knots of bulk shear), so a low-end hail or wind threat could develop.
** TUES & BEYOND **
On Tues, the next upper trough begins to emerge from the lee of the Rockies, with a sfc low forecast to reach southern MN by midday. Guidance continues to show storm development along the associated cold front to the NW of the ILX CWA Tues afternoon, with storms eventually progressing into the area late Tues evening/Tues night. The latest deterministic GFS is faster than the other global models, and is the only one to bring storms into the western parts of the ILX CWA by 00z Wed (7pm Tues). Forecast soundings show steep mid- level lapse rates, as well as moderately-high LCLs (just above 1000 feet) with an inverted-V profile beneath the cloud base. The strong linear forcing of the cold front combined with that low-level thermo profile favoring cold pool development suggests upscale growth into a linear segment by the time the storms reach the ILX CWA Accordingly, damaging winds are the top concern, but a threat of hail and tornadoes will also exist, especially if any discrete cells manage to form ahead of the primary line (which is difficult to assess at this range). Exactly how far east a severe threat will persist into the overnight hours remains a point of uncertainty.
Wed's severe storm potential will depend on how far south the cold front or outflow boundaries from Tues night's storms push. If the front is not completely through the ILX CWA, another round of severe storms could develop along/ahead of the front on Wed as the airmass ahead of the front remains quite unstable. The best chance for this to occur in our CWA would be near/south of I-70, but it is possible the front pushes completely south of the ILX CWA Forecast soundings for Wed do show a more unidirectional shear profile than Tues (lower tornado potential), and deep layer shear vectors are roughly parallel to the front, so a linear mode would be favored once more. Given mesoscale uncertainties such as boundary placement, SPC's confidence was too low to introduce a 15% risk area for Day 5 (Wed). CIPS analogs and CSU machine learning guidance both have the highest severe probs for Wed focused south of I-70.
As sfc high pressure settles in on Thurs behind the cold front, temps will be a bit cooler (highs in the 70s) and mostly dry weather should prevail. Some precip chances linger in the forecast across SE IL due to proximity of the stalled front, but it's possible these PoPs will be removed as confidence in the frontal placement increases over the coming days. Further into the extended, model consistency decreases, resulting in low confidence in any precip chances beyond Thurs.
Erwin
AVIATION
(For the 00z TAFs through 00z Sunday Evening)
Issued at 638 PM CDT Sat May 18 2024
VFR conditions will prevail at all TAF sites next 24hrs. Skies will be clear through the night with scattered CU developing again tomorrow morning. Winds will be light and variable through the 24hr period.
Auten
ILX WATCHES/WARNINGS/ADVISORIES
None.
Area Forecast Discussion...Updated National Weather Service Lincoln IL 912 PM CDT Sat May 18 2024
KEY MESSAGES
- Above normal temperatures will continue through at least Tuesday, with highs in the upper 80s. Tuesday looks like the most humid day of the stretch, resulting in heat indices in the low 90s.
- Isolated storms are possible (20% chance) Sunday afternoon.
While much of the area will stay dry, locally heavy rainfall over 1.5" could occur beneath the storms that do develop.
- A stormy pattern will exist early next week, with potential for severe thunderstorms Monday through Wednesday. During that time frame, the greatest risk is for damaging winds west of I-55 Tuesday evening.
UPDATE
Issued at 912 PM CDT Sat May 18 2024
Skies are clear and winds are light southwest. Current forecast has a good handle on this with temps expected to drop into the middle 60s across the CWA Therefore, no official update is planned at this time.
Auten
DISCUSSION
Issued at 220 PM CDT Sat May 18 2024
For the rest of today, upper level height rises will continue to produce large-scale subsidence. While some areas of agitated Cu are evident on satellite, vertical development seems suppressed and I kept the forecast dry. A cold front is progressing across WI/IA this afternoon, although to this point, storm development has been confined to WI where there is better upper level forcing.
CAMs still show storms forming along the front in IA by late evening, but these quickly dissipate after sundown and are unlikely to reach the NW part of the ILX CWA
A summer-like pattern will exist through the middle of the upcoming work week, with above normal temperatures and storm chances, some of which could be severe. The Tues night-Wed timeframe understandably continues to be the main highlight, but there are other storm chances before then that also warrant discussion. High temperatures will be in the mid 80s to near 90F through Tues, while dewpoints will be in the mid 60s through Mon before climbing to near 70F on Tues. Due to those higher dewpoints, the highest heat indices are anticipated to occur on Tues, with values in the low to mid 90s.
** SUNDAY **
The chance for storms on Sunday is fairly low, as the area remains beneath an upper level ridge axis, but there are still a few potential mechanisms via which storms could form. The weak cold front NW of the area today is progged to move into the CWA late tonight and stall across the area on Sun. While upper support will not be conducive, forecast soundings do show an uncapped environment with moderate instability (2000-2500 J/kg of CAPE) and that front could provide sufficient lift to kick off storms. The latest CAMs suggest this scattered activity, if it were to develop, would occur between the IL River and I-70. Hodographs look crumpled (very weak shear), so similar to Friday I expect any storms to be relatively short-lived, but also slow-moving which could result in very isolated instances of heavy rainfall. HRRR 24-hour LPMM supports that assessment, with a few pockets where rainfall exceeds 1.5".
The other, lower confidence way that storms could impact the area on Sunday is via a convective complex that develops over the west- central Plains late tonight and rolls east across the Plains, potentially reaching west-central IL by Sun evening.
Latest CAMs are not as bullish on this idea compared to previous cycles, now showing the complex dissipating across IA as the nocturnal LLJ weakens and cloud-top warming occurs after sunrise.
Nevertheless, the instability gradient will be oriented such that if these storms hold together they would progress towards areas north of a Macomb- Bloomington line by Sun evening.
** MONDAY **
By 12z Mon, a shortwave and an associated weak sfc low are progged to be lifting towards the upper Midwest, located NW of the ILX CWA As this disturbance lifts north, there could be sufficient ascent to aid t-storm development late Monday morning through Monday evening in areas NW of the IL River. CAPE-Shear parameter space for that area appears marginally supportive of strong/severe storms, with moderate instability (again between 2000-2500 J/kg)
and marginal shear (25-30 knots of bulk shear), so a low-end hail or wind threat could develop.
** TUES & BEYOND **
On Tues, the next upper trough begins to emerge from the lee of the Rockies, with a sfc low forecast to reach southern MN by midday. Guidance continues to show storm development along the associated cold front to the NW of the ILX CWA Tues afternoon, with storms eventually progressing into the area late Tues evening/Tues night. The latest deterministic GFS is faster than the other global models, and is the only one to bring storms into the western parts of the ILX CWA by 00z Wed (7pm Tues). Forecast soundings show steep mid- level lapse rates, as well as moderately-high LCLs (just above 1000 feet) with an inverted-V profile beneath the cloud base. The strong linear forcing of the cold front combined with that low-level thermo profile favoring cold pool development suggests upscale growth into a linear segment by the time the storms reach the ILX CWA Accordingly, damaging winds are the top concern, but a threat of hail and tornadoes will also exist, especially if any discrete cells manage to form ahead of the primary line (which is difficult to assess at this range). Exactly how far east a severe threat will persist into the overnight hours remains a point of uncertainty.
Wed's severe storm potential will depend on how far south the cold front or outflow boundaries from Tues night's storms push. If the front is not completely through the ILX CWA, another round of severe storms could develop along/ahead of the front on Wed as the airmass ahead of the front remains quite unstable. The best chance for this to occur in our CWA would be near/south of I-70, but it is possible the front pushes completely south of the ILX CWA Forecast soundings for Wed do show a more unidirectional shear profile than Tues (lower tornado potential), and deep layer shear vectors are roughly parallel to the front, so a linear mode would be favored once more. Given mesoscale uncertainties such as boundary placement, SPC's confidence was too low to introduce a 15% risk area for Day 5 (Wed). CIPS analogs and CSU machine learning guidance both have the highest severe probs for Wed focused south of I-70.
As sfc high pressure settles in on Thurs behind the cold front, temps will be a bit cooler (highs in the 70s) and mostly dry weather should prevail. Some precip chances linger in the forecast across SE IL due to proximity of the stalled front, but it's possible these PoPs will be removed as confidence in the frontal placement increases over the coming days. Further into the extended, model consistency decreases, resulting in low confidence in any precip chances beyond Thurs.
Erwin
AVIATION
(For the 00z TAFs through 00z Sunday Evening)
Issued at 638 PM CDT Sat May 18 2024
VFR conditions will prevail at all TAF sites next 24hrs. Skies will be clear through the night with scattered CU developing again tomorrow morning. Winds will be light and variable through the 24hr period.
Auten
ILX WATCHES/WARNINGS/ADVISORIES
None.
| Airport | Dist | Age | Wind kt | Vis | Sky | Weather | Temp | DewPt | RH | inHg |
| KSPI ABRAHAM LINCOLN CAPITAL,IL | 17 sm | 44 min | no data | -- | 29.90 | |||||
| KIJX JACKSONVILLE MUNI,IL | 23 sm | 21 min | S 03 | Clear | 72°F | 63°F | 73% | 29.90 |
Central Illinois, IL,
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