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FXUS63 KDMX 181952 AFDDMX

Area Forecast Discussion National Weather Service Des Moines IA 252 PM CDT Thu Apr 18 2024

KEY MESSAGES

- Showers and storms ending southeast this evening with skies clearing from northwest to southeast statewide.

- Freezing temperatures possible tonight resulting in Frost Advisories and Freeze Warnings for the state.

- Gusty winds on Friday, mainly across northern Iowa. Freezing temperatures likely again Friday night into Saturday, then again Saturday night into Sunday.

DISCUSSION
Issued at 247 PM CDT Thu Apr 18 2024

>> Showers & Storms Departing This Afternoon

After a moist morning across the forecast area, rain has departed all but southeastern Iowa where scattered showers and a few thunderstorms remain. Fortunately, the better instability has stayed south of the state and therefore severe weather chances for this afternoon have diminished. These showers and storms will exit Iowa through the late afternoon as the cool front continues through the state. Behind this boundary, cooler and drier air has begun to funnel in and erode cloud cover in northwest Iowa. Cloud cover will continue to diminish from northwest to southeast through the afternoon and evening hours, leaving mostly clear skies through the overnight.

>> Frost and Freeze Conditions Tonight

With colder air advecting into the area, clearing skies, and diminishing winds, expecting some efficient cooling through the night with temperatures dropping into the low to mid 30s by early Friday morning. With recently warmer temperatures and rainfall, much of the vegetation across the area has started to green up and growing seasons will be beginning soon. Therefore, in collaboration with neighboring offices, have issued a freeze warning for much of northern, central and western Iowa where temperatures will be near to below freezing. Similarly, a frost advisory has been issued for counties further south and east in the state where temperatures will be slightly warmer (mid 30s) but dewpoints still fall into the upper 20s to low 30s with light winds, posing the risk for frost. That being said, with strong radiational cooling expected, lows very well could fall below what is currently forecast, so all areas should be prepared for freezing temperatures and/or frost on Friday morning.

>> Breezy Tomorrow

Friday looks to be breezy as an upper level ridge passes to the north of the state, bringing tightened pressure gradients and a decent jet aloft that will be maximized over northern Iowa. With clear skies and the passage of another cold front, winds should have no problem mixing down to the surface, producing gusty winds along this boundary and beneath the jet across the north. The strongest winds will likely be sustained at 20 to 25 mph, with gusts exceeding 35 mph at times in the afternoon. That being said, not anticipating much fire weather concern with the two recent rainfall events keeping fuels moist. Tomorrow night, temperatures will be even cooler with widespread lows below freezing, making freeze headlines likely again tomorrow night into Saturday morning.

>> Seasonal Temperatures Next Week, Rain Chances Return

Outside of overnight freezing temperatures this weekend and gusty winds tomorrow, the forecast looks relatively quiet through the weekend. Temperatures will begin to warm back to normal through the beginning of next week, with a few chances for rain early and late week. The first of these looks to be on Monday, with the chance for both rain and a few thunderstorms. This system is still a ways out, but as of right now it looks like modeled precipitation is favoring northern Iowa. There is little concern for severe weather at this time as most of the instability stays outside of the state. Beyond that, we will have to wait until closer to the event when details are clearer.

AVIATION /18Z TAFS THROUGH 18Z FRIDAY/
Issued at 1231 PM CDT Thu Apr 18 2024

MVFR and IFR ceilings across the area this morning will begin to see improvement as clouds depart from northwest to southeast this afternoon and evening. Rain is also diminishing in coverage, but a few showers and isolated thunderstorms will continue near KOTM through the next few hours, resulting in periods of lower visibility, gusty winds and potentially some lightning.

After clouds depart, VFR conditions prevail through the overnight hours and into tomorrow morning, barring a few scattered low cumulus developing towards mid-day tomorrow. Gusty west northwest winds are also expected after sunrise tomorrow.

DMX WATCHES/WARNINGS/ADVISORIES
Freeze Warning from 1 AM to 8 AM CDT Friday for IAZ004>007- 015>017-023>028-033>038-044>046-057-070.
Frost Advisory from 1 AM to 8 AM CDT Friday for IAZ039-047>050- 058>062-071>075-081>084-092>095.

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