Area Forecast Discussion
Issued by NWS Des Moines, IA
Issued by NWS Des Moines, IA
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012 FXUS63 KDMX 252316 AFDDMX Area Forecast Discussion National Weather Service Des Moines IA 616 PM CDT Wed Sep 25 2024 ...Updated for the 00z Aviation Discussion... .KEY MESSAGES... - Above normal temperatures in the upper 70s to mid 80s continue through the weekend. - Late week precipitation chances continue to dwindle with dry forecast prevailing into next week. - Cooler, fall temperatures incoming next week. && .DISCUSSION... Issued at 254 PM CDT Wed Sep 25 2024 Upper level pattern characterized by a closed low over the mid Mississippi Valley, a ridge over much of the western into central U.S., and Hurricane Helene in the Gulf of Mexico. The ridge axis moves over the upper Midwest tomorrow with high pressure continuing to dominate the forecast in Iowa at the surface through the end of the week and even into the weekend north/northwest. What does this mean for our weather? Well, the dry, pleasant, albeit warmer than normal conditions are here to stay through the rest of the week and into the weekend. (Note, normal temperatures for this time of year are in the low to mid 70s for highs, and mid 40s to low 50s for low temperatures.) As noted in the previous discussion, the precipitation chances associated with the remnants of Hurricane Helene as the system merges with the cutoff low over the Ohio- Tennessee Valley Region continue to dwindle with a completely dry forecast in the area through the next 7 days as ensembles and deterministic guidance come into better agreement that precipitation chances remain to the east/southeast of the area. We will see some increasing cloud cover associated with the system Thursday night through Friday night mainly south to the southeast half of the area which may help keep temperatures a couple degrees cooler in the south. Otherwise, high temperatures in the upper 70s to mid 80s persist through the weekend and to start next week. Tomorrow/Thursday will likely see another round of diurnal cumulus similar to this afternoon with another chance for patchy fog to start the day. Overall confidence in fog impacts remain low with hi-res guidance suggesting only as high as a 35% probability that visibility will be less than 5 miles in the northeast early Thursday morning and less than 15% anywhere that visibility will be less than 1 mile. Would expect any fog to be our typical foggy spots like river valleys, if any. As we get into next week, a stark change is expected as a dry cold front brings fall temperatures to the area on Tuesday with highs only in the 60s, a 10-15 degree temperature drop from Monday. The fall temperatures then look to persist as a Canadian high pressure moves into the area keeping temperatures cooler, but then also conditions dry. && .AVIATION /00Z TAFS THROUGH 00Z THURSDAY/... Issued at 613 PM CDT Wed Sep 25 2024 VFR conditions and light winds are forecast for the period. There remains a low chance of fog late tonight. Included a second line in the forecast only to give prevailing wind direction indication for Thu. && .DMX WATCHES/WARNINGS/ADVISORIES... None. && $$ DISCUSSION...KCM AVIATION...Donavon