textproduct: Quad Cities

This forecast discussion was created in the public domain by the National Weather Service. It can be found in its original form here.

KEY MESSAGES

- Our wet weather pattern continues tonight through Monday night, with two additional rounds of showers and embedded thunderstorms. An additional 1 to 2+ inches of rain are expected for most locations.

- Isolated strong to severe storms are possible late Monday, mainly south of Interstate 80.

- Drier, more seasonable weather is forecast by the middle to end of the week with highs in the 50s.

SHORT TERM /THROUGH MONDAY NIGHT/

Issued at 158 PM CST Sun Nov 3 2024

As of 2 PM this afternoon, we continue to see the last of the first of three rounds of showers lifting northward over areas along and north of Highway 30. This wet pattern will only continue tonight through Monday night as we remain under a well-defined meridional pattern with a slowly amplifying upper-level ridge over the southeastern CONUS and a longwave upper trough over the Intermountain Region, placing our region under a predominant southwesterly flow/warm air advection regime aloft. A few additional shortwave troughs and the nocturnal low-level jet (LLJ) will continue to support a few more rounds of showers and isolated thunderstorms. Unlike early this morning, the 40 to 50 knot 850 mb LLJ will be shifted a bit more to the east as the parent upper trough approaches the region, resulting in very efficient theta-e transport over areas along and east of the Mississippi River. This can be seen in the ECMWF ensemble mean integrated water vapor transport (IVT), which has climatological percentiles of 99% or higher! Additionally, Pwat values of 1 to 1.6 inches are expected, which are also around 99.5% of climatology, so lots of moisture still to come! Tonight's wave of showers doesn't appear to be quite as strong as the wave that's expected for late Monday, but we are still expecting more activity late tonight. Tonight's temperatures should remain quite steady compared to today's highs, with lows in the middle 50s north to around 60 south.

As we head into the day Monday, the aforementioned LLJ and shortwave will lift northeastward with time, leading to a relative lull in the showers during the daylight hours. Some scattered activity could still in our area, but it doesn't appear to be as widespread as we had this morning. The warm air advection and relative lack of rainfall should help temperatures warm into the middle to upper 60s across the area, which is quite warm for this time of the year (average high temperatures are around the lower to middle 50s this time of the year!).

Attention will quickly turn to Monday evening into the overnight as the third and final round of showers and storms moves through the area. This will be one to keep an eye on as this round will come with the chance of an isolated strong to severe storm as SPC continues to have areas just south of the Quad Cities in a Marginal Risk (level 1 of 5) of severe weather. A surface low that is expected to develop over the TX Panhandle Monday morning will make its way northeastward with time, arriving in our forecast area by late Monday. Instability continues to be pretty meager, with most- unstable CAPE progged at or less than 500 J/kg, but the nocturnal LLJ should help enhance convergence/deep-layer shear with values of 50 knots to larger. Additionally, the mid-level flow will be enhanced, with magnitudes around 50 to 70 knots, so a damaging wind threat will be possible with any severe storms, along with a low chance of a tornado if any convection can become surface- based, which appears unlikely at this time. The anticipated timing of these potentially strong storms should be around 5 PM to midnight.

This third round of storms Monday night will also pack the highest moisture content of this entire period of rainfall, with both ECMWF ensemble IVT and Pwat values approaching the max values of the climatological percentiles! This should lead to very efficient rainfall rates, with overnight totals in the 1 to 2 inch range for areas along and east of the Mississippi River. These values could set some daily record precipitation for some locations, so please see our Climate section below for the rainfall records for Monday. This rainfall could lead to ponding of water for urban areas, especially for low-lying areas with poor drainage. Newly fallen leaves clogging storm drains could exacerbate this issue, so some ponding/standing water in low- lying areas could be a problem.

LONG TERM /TUESDAY THROUGH SUNDAY/

Issued at 141 PM CST Sun Nov 3 2024

The surface low will continue to lift northeastward during the day Tuesday, so some lingering showers and perhaps an isolated thunderstorm will be possible during the morning hours. Eventually, this activity will taper off during the PM hours, leading to a period of dry, more seasonal conditions for mid-week. An area of high pressure will take control over the region Wednesday through Friday, with perhaps a slight chance (20 to 30 percent) of showers late in the day Friday.

High temperatures Wednesday through Saturday will be in the upper 50s to near 60, with lows in the middle to upper 30s.

AVIATION /00Z TAFS THROUGH 00Z TUESDAY/

Issued at 552 PM CST Sun Nov 3 2024

As the main Sunday precip shield lifts off to the northeast acrs WI, in it's wake acrs the local area will be a challenging mix of remnant IFR CIGs and some fog, MVFR CIGs, and patches of VFR CIGs mixing in from the south. After the improvement this evening, another slug of moisture aided by the feed of a 30 KT southerly LLJ and vort max aloft, will lower CIGs again as well as support the next round of showers after midnight and into early Monday morning. MVFR to IFR CIGs and VSBYs again with this late night activity. Then expect some improvement again to MVFR or even VFR CIGs/VSBYs by Monday afternoon in between the waves of rain. The chance for some embedded thunder is there later tonight into Monday morning, but the probability is less than 20% and thus will keep out of TAF mention for now.

CLIMATE

Issued at 225 PM CDT Sat Nov 2 2024

Record Daily Precipitation Amounts:

November 4: KBRL: 1.61/1935 KDBQ: 1.61/2022 KMLI: 1.51/2022

DVN WATCHES/WARNINGS/ADVISORIES

IA...None. IL...None. MO...None.


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