February 23: Weather Roller-Coaster, Daily Links

WEATHER

Patchy dense fog this morning is burning off as I’m typing this…we’ll see a mix of clouds and sunshine overhead the rest of the day.  Unusually warm temperatures once again — we’ll reach the low to mid 70s this afternoon:
thursday-highs

Warm and increasingly breezy tonight, with lows only dropping to around 60°:
friday-lows

We’ll rocket up to near 80° by Friday afternoon!
friday-highs
Tomorrow’s record high temperature is 77° set all the way back in 1890 — obviously it looks more likely than not that we’ll have a new record on the books.  The all-time warmest temperature for the month of February in Nashville is 84° — I don’t think we’ll be that warm, but I can’t rule it out.  It will be breezy throughout the day, with southerly gusts up to around 30 mph:
paul-rpm-wind-gusts
The National Weather Service office in Nashville might decide to issue a Wind Advisory for tomorrow, but regardless of that you should make sure your lawn furniture and trash cans are secure.

Still a good chance of thunderstorms in the forecast Friday evening — the RPM model’s radar simulation shows them initially popping up around 6pm, then moving rapidly west-to-east throughout the evening and early overnight:
rpm-6p-fri rpm-8p-fri rpm-10p-fri rpm-12a-sat

Will the storms be severe?  That’s the million-dollar question at this point, but things are still looking “iffy” in terms of our severe potential in the Midstate.  The environment ahead of the storms will certainly be warm, and the wind energy overhead will likely be impressive…but the atmosphere won’t be all that humid, which is a major limiting factor.  Dew points are only forecast to be in the mid 50s Friday evening, which is really borderline:
paul-rpm-4km-dew-point
If you were designing a severe-weather environment, you’d want dew points to be at least 60°, and ideally in the mid 60s.  But the other ingredients are favorable enough for the one of the ensemble models (think of it as a “blend” of different forecast models) to indicate a chance anywhere from 20-50% of storms with severe weather ingredients Friday evening, highest to the northeast of Nashville:
sref_prob_combined_supercell__f042 sref_prob_combined_supercell__f048
The “analog” forecast method (comparing Friday evening’s large-scale pattern to similar historical patterns) shows a 40% chance of 5+ severe weather reports Friday evening:
prallc05_nam212f048
Remember, “severe” means something very specific: 60+mph winds, 1″+ diameter hail, or a tornado.  Considering all of that data, the Storm Prediction Center has outlined a “Slight Risk” (level 2 out of 5) for severe storms in southern Kentucky and northeastern Middle Tennessee, with a “Marginal Risk” (level 1 of 5) for the rest of the Midstate:
paul-severe-risk-region
Damaging winds will be the main threat associated with any severe storms, but the way the winds will be arranged in the lowest 3 km of the atmosphere means I can’t rule out an isolated tornado — the greatest threat of severe weather will take shape to our north, in Indiana and Ohio.

Friday night’s storm system will bring in substantially cooler air for the weekend:
wsmv-4-plus-4-am-1

But temperatures will turn right back around as we head through next week:
wsmv-4-plus-4-am-2
Rain will move in from the west late Sunday night into early Monday.  Spotty showers (maybe a few storms?) on Tuesday with very warm temperatures, then another cold front will help to enhance our thunderstorm chances on Wednesday.  It’s WAY too soon to worry about any severe potential with that one.

 

LINKS

TONS of stuff about yesterday’s announcement from NASA.  Plus other assorted weather and science nerdery…

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About paulheggen33

Morning meteorologist for WSMV-TV in Nashville.
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