Area Forecast Discussion
Issued by NWS Quad Cities, IA IL
Issued by NWS Quad Cities, IA IL
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987 FXUS63 KDVN 190543 AFDDVN Area Forecast Discussion National Weather Service Quad Cities IA IL 1243 AM CDT Thu Sep 19 2024 .KEY MESSAGES... - Above normal temperatures continue through Saturday. - Active weather returns to the area Thursday through Monday. - There is a SLGT risk of severe thunderstorms for portions of eastern IA Thursday late afternoon through the evening. && .UPDATE... Issued at 704 PM CDT Wed Sep 18 2024 Severe storms, especially supercells, are looking possible tomorrow late afternoon into the evening before becoming more linear/cluster in nature well after dark. The better forcing during peak heating looks to be just west of our area so storms should initiate west of the area. I am not convinced in the timing that the CAMs suggest for us as they seem to be too late with timing, as such we need to adjust potential threats from this system. Soundings depict high bases with modest instability at the sfc that becomes capped later in the day. They also depict a well curved low level hodograph. While speed shear isn`t all that impressive, the curvature of the soundings strongly suggests low level rotation and overall supercell nature of the storms. This is especially true as the deep layer shear vector is perpendicular to the forcing, leading to supercells. Large hail looks to be the main threat from these storms. With the high bases, normally this will lead to a lower tornado threat. However, if these supercell storms enter the CWA as the LLJ ramps up we could see a quick 1 to 2 hour window where a sneaky tornado threat could set up, especially across the slight risk area. As such have adjusted messaging to include this tornado. && .SHORT TERM /THROUGH FRIDAY/... Issued at 155 PM CDT Wed Sep 18 2024 Tonight: One more quiet night ahead with partly cloudy skies with some cirrus clouds. Lows in the mid to upper 50s east to the lower 60s west. Thursday: After about 3 weeks of dry weather the pattern begins to become much more active. We start out with a bang with SPC highlighting portions of eastern IA in a SLGT risk (Level 2 of 5) for portions of eastern IA, with a MRGL risk roughly to the MS River. While isolated showers are possible on Thursday, the bulk of the showers and storms, some severe, will arrive late in the afternoon through the evening. Severe potential: A seasonably strong stacked low in southern Manitoba will send a cold front southeast towards the forecast area. This will pull very warm and increasing humid air into our area with highs in the upper 80s to possibly lower 90s in a couple of spots. Dewpoints will also increase well into the 60s ahead of the front. Models show mid level winds from the west strengthening to 40 kts during the afternoon and evening. Shear/instability will be more than sufficient to support the potential for large hail and damaging winds, with the activity weakening by late evening with the loss of instability. && .LONG TERM /FRIDAY NIGHT THROUGH WEDNESDAY/... Issued at 155 PM CDT Wed Sep 18 2024 Active weather continues Friday through Monday with zonal west to east flow across North America. There are two closed 500 MB lows that will bring chances of showers and storms to the area during this time period. The first passes to our north Saturday into Saturday night. The second will lift from the southern High Plains and cross the area Sunday into early next week. Models continue to disagree on the timing and placement of these storms and any interaction between the two late this weekend into early next week. This continues to result in broad brush POPS across the area through the period. This will also result in cooler high temperatures especially Sunday into early next week. && .AVIATION /06Z TAFS THROUGH 06Z FRIDAY/... Issued at 1230 AM CDT Thu Sep 19 2024 VFR conditions are forecast through the TAF period. There is a low chance of rain showers at KCID from 15 to 18 UTC but confidence is very low in this occurring so these were left out of the TAFs for now. A line of showers and thunderstorms are forecast to develop to our west during the late afternoon nand move eastward across eastern Iowa from 00 UTC to 06 UTC. Have placed a prob30 group at KCID, KDBQ, and KMLI to account for this. Confidence is lower that this line of storms will move into KBRL before the end of the TAF period. MVFR ceilings and visibilities are possible in the strongest storms. && .DVN WATCHES/WARNINGS/ADVISORIES... IA...None. IL...None. MO...None. && $$ UPDATE...Cousins SHORT TERM...Haase LONG TERM...Haase AVIATION...Gibbs