Area Forecast Discussion
Issued by NWS Des Moines, IA
Issued by NWS Des Moines, IA
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973 FXUS63 KDMX 161743 AFDDMX Area Forecast Discussion National Weather Service Des Moines IA 1243 PM CDT Thu May 16 2024 ...Updated for the 18z Aviation Discussion... .KEY MESSAGES... - Scattered showers and isolated storms ending east this morning. - Warmer Friday into Saturday with highs into the 80s. - Active pattern Sunday afternoon into early next week. Threat for severe weather and heavy rainfall may develop Sunday night and again Monday night into Tuesday, although specific details remain uncertain at this time. && .DISCUSSION... Issued at 316 AM CDT Thu May 16 2024 Weak convection continues across portions of north central into northeast Iowa early this morning ahead of a weak boundary passing into the state. Otherwise, some patchy fog has developed ahead of the boundary in portions of southern Iowa and this is likely to persist in advance of the front through daybreak. Otherwise, the front advances eastward across much of the forecast area by midday with increasing subsidence and drier air overspreading much of the area. The exception may be the far southeast where some redevelopment occurs prior to frontal passage but any activity would quickly exit the area into eastern Iowa. Cold advection is most pronounced across northern Iowa today but good mixing and some sunshine should keep temperatures similar in most areas to Wednesday`s highs or perhaps slightly warmer in the south where the cold advection is much more negligible. An upper trof across western Canada into the northwest United States has a shortwave passing through the base on Friday into Saturday over the northern US Rockies. Warm advection ahead of this system is expected to intensify across Iowa tonight into Friday with increasing southerly surface flow. Temperatures should respond in kind by Friday afternoon as highs climb into the 80s over much of the area with ample insolation through the day. As the upper system pushes through North Dakota and Minnesota, it sends a boundary across Iowa on Saturday. Instability develops ahead of this front by afternoon with MUCAPES in vicinity of 1500-1800 J/KG however soundings indicate a decent cap is in place for much of the day. Sufficient mechanical forcing near the front may be enough for a few isolated storms during peak heating but it appears to remain limited at this point. Beyond this point, broad west to southwest flow develops across much of the United States heading into next week. Both the GFS and Euro indicate strong return flow on Sunday with moisture surging back north into the state with increasing chances of storms by the afternoon in the west. Chances overspread much of the state into Sunday night as the low level jet veers over Iowa. Additional convection seems likely on Monday into Tuesday as a surface wave develops along a boundary in Kansas and moves northeast toward Iowa. The threat for heavy rainfall is expected during this time along with some potential for severe weather. && .AVIATION /18Z TAFS THROUGH 18Z FRIDAY/... Issued at 1232 PM CDT Thu May 16 2024 Cumulus has developed across much of the area. While there still could be a localized brief MVFR cig, the cigs are rising with daytime mixing leading to cloud bases above 3 kft. In addition to the rising cigs, the clouds will begin to diminish in areal coverage by mid afternoon, except the far northeast. West wind today will become light tonight and transition to southerly by Friday morning. && .DMX WATCHES/WARNINGS/ADVISORIES... None. && $$ DISCUSSION...Cogil AVIATION...Donavon