Busy weather map today (21 Sept 2021)

First, those in the Coastal Georgia and Lowcountry of South Carolina, it rained yesterday. A Lot. Savannah airport hit a record 6.66 inches (ok, that’s not ominous), breaking the old record of 2.12 for this date (which was low for a record, but has stood since 1885!). In midtown Nicholas says we got 6.51 inches, so it was pretty uniform heavy rain over the area. More rain predicted for today, probably not so much as yesterday, but watch for street flooding in the usual places. Here’s the TAFB weather map for this morning …

click for the details.

The stalled front (jagged line) with a low pressure “L” symbol over Georgia is the reason for all the rain. If you follow the front around to the east (right), you’ll see it ends in the label “storm” next to a Low pressure symbol. That’s what used to be Odette, now a winter storm.

There is less going on in the tropics than meets the eye. Yes, there are two tropical storms, Peter and Rose, but both are disorganized – notice that the heavy convection (oranges on the IR satellite image) are displaced from the center (the storm symbols) and not wrapping around them. That’s a sure sign of strong wind shear, and in fact NHC says in the latest bulletins that both storms will probably be torn apart in the next couple days.

There is some angst about a wave coming off of Africa, AL98 (Disturbance #1 on the NHC Tropical Weather Outlook), which has an 80% chance of spinning up. Run to run consistency has been fairly good for the GFS model, showing this system becoming a tropical storm in the next week. The longer range (10 day) forecasts are showing it following the same trajectory as most of the storms this year, north of the Leeward Island then east of Bermuda. But that’s along way off, and again if the magic words “Interests <somewhere> should <do something>” don’t appear in the NHC messages and/or you aren’t “somewhere”, don’t worry about it. If you’re curious, here’s the image swiper comparison tools for the GFS runs initialized at 8am yesterday morning and 8pm last night … this is amazingly consistent (but, as a caution, can rapidly change given the complexity of the atmosphere – 10 day forecasts are getting better but can still rapidly change). Slide right for the old run, left for the new run.

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