Area Forecast Discussion
Issued by NWS Quad Cities, IA IL
Issued by NWS Quad Cities, IA IL
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504 FXUS63 KDVN 151911 AFDDVN Area Forecast Discussion National Weather Service Quad Cities IA IL 211 PM CDT Sat Jun 15 2024 .KEY MESSAGES... - Chances of showers and thunderstorms increase late tonight, some of which could be strong - Conditions becoming hot and humid Sunday, lasting through Tuesday - A relative break from the heat is expected by Wednesday as a cold front moves through the area, supporting periodic chances of showers and storms through Friday && .SHORT TERM /THROUGH SUNDAY/... Issued at 208 PM CDT Sat Jun 15 2024 This afternoon, we continue to see the remnants of AM showers and storms continuing to move into our region. As this activity moves through, it will continue to diminish as it encounters a very dry air mass in place, so local impacts should be minimal. There will be increasing chances of showers and storms late tonight, mainly after midnight, which should be more robust as a mid-level shortwave skims across our northwestern areas. Additionally, a southwesterly 40 to 50 knot low-level jet will accompany the shortwave, which will aid in forcing for ascent. CAMs are struggling a bit on the exact timing and areal coverage of convection across our northwestern forecast area, and it remains uncertain just how far south storms will develop. In any case, some strong storms will be possible as deep-layer shear is now progged around 30 to 40 knots, and most-unstable CAPE values around 500 to 1500 J/kg per the HREF ensemble mean. Soundings indicate convection to be more elevated in nature, but with meager mid-level lapse rates, locally gusty winds will be the main threat, with a lesser threat for hail. SPC continues to paint a Marginal Risk (level 1 of 5) across our western tier of counties for tonight. Eventually, the aforementioned shortwave trough will lift northeastward by mid-morning Sunday, bringing any lingering showers and storms to an end. Attention will quickly turn to a breezy, hot day on Sunday. A large upper-level ridge will develop over the eastern CONUS, with a large upper-level high pressure system over the southeastern CONUS, which will support a prolonged period of southerly flow/warm air advection into our region. Humidity will also be noticeably higher, although there are some questions on just how high the dew points will be, given a spread of nearly 4 to 8 degrees off the HREF 25th and 75th percentiles. However, with 850 mb temperatures between 19 to 21 degrees C per the GEFS and EC ensembles, which are over 90 percent of climatology, temperatures warming to the lower to middle 90s are expected, along with heat indices in the middle to upper 90s for most locations. We are not planning any Heat Advisory headlines at this time as the likelihood for locations reaching 100 degree heat indices is a bit low and isolated at this time. Southerly winds will be breezy Sunday, with gusts between 20 to 30 mph expected. These winds could help provide some relative relief to the heat. && .LONG TERM /SUNDAY NIGHT THROUGH FRIDAY/... Issued at 208 PM CDT Sat Jun 15 2024 Hot and humid conditions continue Monday and Tuesday as the large- scale pattern changes very little. Monday is likely to be a hair warmer/more humid than Sunday, with higher probabilities of Tds in the upper 60s per the LREF, which takes into account the GEFS, ENS, and GEPS ensembles. 850 mb temperatures per the GEFS and ENS appear to be pretty consistent over the last several runs, with values continuing around 18 to 21 degrees C. The NBM continues to be on the high side of the model spectrum, with values generally over the 75th percentile, so we did cool the highs slightly for Monday, but still largely remaining in the middle to upper 90s for highs. Max heat indices will continue to be in the middle to upper 90s for most of the area as well, so make sure to take extra precautions to protect yourself from the heat. As mentioned over the last few forecast packages, record high temperatures should remain intact, but we have the potential for breaking several record warm lows Sunday night and Monday night, with overnight lows in the middle to upper 70s. Please see the Climate section below for the records that could be tied or broken. A pattern change is expected to occur by mid-week next week, as the upper-level ridging over the eastern US breaks down, and a longwave trough develops over the Intermountain West region. As the trough approaches, an attendant cold front will sweep through the area around Wednesday, which will bring widespread chances (30 to 60%) of showers and storms. This should bring at least some relative relief to the upcoming heat and humidity, although high temperatures in the upper 80s to lower 90s remain possible for Wednesday through Friday. A few additional mid-level shortwaves are expected to overtop the ridge into our area, so additional chances of precipitation will be in place through the end of the week. && .AVIATION /18Z TAFS THROUGH 18Z SUNDAY/... Issued at 1221 PM CDT Sat Jun 15 2024 Largely VFR conditions are expected through the TAF period. Our main focus for this set continues to be on a round of showers and storms expected late tonight. The latest high-resolution models show quite a bit of spread in the areal coverage of storms, so confidence is lower on the timing for any storms that impact local terminals. However, CID and DBQ remain the most likely terminals to see any storms, so continued the PROB30 groups for them, with brief MVFR/IFR conditions possible under the heaviest storms. As we get closer to the event, TEMPOs will likely be needed. Additionally, a 40 to 50 kt southwesterly low- level jet is expected tonight, so we have introduced LLWS to the TAFs to account for it. Gusty southerly winds are expected at times, especially during the daylight hours Sunday. && .CLIMATE... Issued at 315 AM CDT Sat Jun 15 2024 Record High Temperatures: June 17: KBRL: 98/1944 KMLI: 98/1897 Record Warm Minimum Temperatures: June 17: KDBQ: 74/1921 KMLI: 78/2018 June 18: KDBQ: 74/1921 KMLI: 77/2018 June 19: KDBQ: 76/1931 KMLI: 78/1953 June 20: KDBQ: 74/1923 June 21: KDBQ: 72/1995 KMLI: 75/1923 && .DVN WATCHES/WARNINGS/ADVISORIES... IA...None. IL...None. MO...None. && $$ SHORT TERM...Schultz LONG TERM...Schultz AVIATION...Schultz CLIMATE...Schultz/Uttech