Area Forecast Discussion
Issued by NWS Des Moines, IA

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826 FXUS63 KDMX 102054 AFDDMX Area Forecast Discussion National Weather Service Des Moines IA 354 PM CDT Mon Jun 10 2024 .KEY MESSAGES...
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- Pleasant this afternoon and tonight. - Showers (few storms) Tuesday morning followed by afternoon redevelopment which may bring a few strong to marginally severe storms during the afternoon to early evening hours, mainly in the northeast quadrant of the area, and with the primary threats of gusty winds and hail. - Active weather pattern continues Wednesday and Thursday with additional chances for strong to severe storms. - Continued warming into midweek as highs reach into the 90s. - Slightly cooler/drier Friday but heat and storm chances return for the weekend.
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&& .DISCUSSION...
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Issued at 331 PM CDT Mon Jun 10 2024 Rest of Today Through Tuesday: Today`s the last more comfortable and pleasant day for the next several - get outside and enjoy it! High pressure that has been drifting through the region today departs tonight with winds gradually switching to be out of the southwest through the evening hours. With much warmer temperatures to the west given the upper ridging in place through much of the western U.S., temperatures will be warmer overnight west as warm air advection increases with better radiational cooling far east leading to a 10+ degree temperature gradient west to east overnight. Clouds also start to increase overnight west to parts of central as the shortwave trough and associated frontal boundary cross from the Upper Plains into the Upper Midwest. Scattered showers start to form in the warm air advection wing ahead of the approaching boundary as moisture increases towards the early morning hours Tuesday northwest with these showers and possibly a few non-severe storms making their way northwest to southeast into around midday. Coverage may decrease with southern extent as forecast soundings reveal much less moisture to work with limiting overall precipitation in general far south or making it harder to reach the ground with ample dry air to overcome. The boundary moves through during the afternoon hours bringing the opportunity for some redevelopment during a few hour window on Tuesday afternoon to early evening, mainly near to east of I-35 and north of I-80, which is roughly the location of the SPC Day 2 Marginal (1 out of 5) Risk. Although forcing is overall fairly weak, if everything comes together a few strong to marginally severe storms are possible with gusty winds and hail the primary threats, though the instability gradient of CAPE values >1000 J/kg is fairly narrow and dependent on atmospheric recovery and overcoming a CAP evident in some soundings. A few models are much more robust with the extent of warming/moisture with dew points in the upper 50s or even 60s which would lead to higher CAPE values to go along with the 35-40+ knots of 0-6 km bulk shear. Given the overall parameter space, coverage is likely to be isolated with any lingering storms moving out of the area by mid to late evening. Temperatures will be noticeably warmer and more humid Tuesday as we start our warming trend through mid week with highs generally in the 80s. Wednesday/Thursday: Warm air advection amplifies further on Wednesday as mid-level flow remains out of the southwest and much stronger moisture transport surges dew points into the 60s. This will create a warm, humid, and unstable environment allowing for better storm organization along a surface boundary as it moves through MN/SD and eventually into Iowa. Some questions remain in the speed of this frontal boundary which will determine the location for any more organized storms Wednesday afternoon/evening and again on Thursday afternoon and evening as storms reinitiate along the boundary further south on Thursday in another warm and unstable environment. With mesoscale details helping to drive the ultimate threats and locations both days, stay tuned for additional updates but the SPC has a Slight Risk (2 out of 5) clipping the area north on Wednesday and in the south on Thursday with an environment certainly supportive of strong to severe storms both days. As noted above, both days will be warm and humid with highs in the 80s to 90s and heat indices nearing 100 far south Thursday. Friday and Beyond: A break in the action is expected on Friday with a slightly cooler and drier forecast, though still in the 80s, before more storm chances and heat return for the weekend as we return to the upper 80s to 90s by Sunday.
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&& .AVIATION /18Z TAFS THROUGH 18Z TUESDAY/... Issued at 1231 PM CDT Mon Jun 10 2024 VFR conditions expected to continue through the bulk of the TAF period. Light winds this afternoon out of the east to northeast will continue to shift through the afternoon becoming out of the southeast and then south this evening into tomorrow morning before increasing Tuesday morning. Clouds will also start to increase overnight mainly west moving eastward through the morning hours. There remains a low chance for light rain Tuesday morning but confidence in coverage limits mentions at specific TAF sites at this time, though conditions will continue to be monitored and -SHRA or -RA mentions may be included in future issuances at especially northern sites. && .DMX WATCHES/WARNINGS/ADVISORIES... None. && $$ DISCUSSION...KCM AVIATION...KCM