Sunday of calm convection

The holiday weekend should not be spoilt much by storms. Expect a ton of sunshine the rest of the day.  Expect more of the same tomorrow too. We have a beautiful Memorial day to which to look forward.  Upper level dryness is there, and while the atmosphere is inherently (conditionally) unstable, it just doesn’t look great for widespread T-Storms today.  It’s mostly the fault of the bone dry uppers, but also because of a generally calm windfield. Storms just won’t move today, limiting them to the coast, and also the Lake O region.

THE WRF SHOWS ALMOST NO ACTIVITY ACROSS THE EAST COAST
METRO AREAS THIS AFTERNOON...BUT WITH SLOW/ERRATIC STORM MOTION
EXPECTED...OUTFLOW BOUNDARIES COULD INITIATE ACTIVITY FURTHER EAST
SO WAS HESITANT TO LOWER POPS THERE.

THE MIAMI SOUNDING THIS MORNING WAS UNSTABLE IN THE LOW LEVELS BUT
MID LEVELS HAD WEAK LAPSE RATES...SO MOSTLY ORDINARY STORMS ARE
EXPECTED...BUT A FEW COULD CONTAIN WIND GUSTS UP TO 45 MPH GIVEN
THE DRY MID LEVELS. /GREGORIA

Once you hit about 800mb (which today is at 6600 feet), the atmosphere really starts to dry out.  It gets very dry until about 300mb.  Below 800mb its very very humid. What this means is any air that rises from the surface will lose its moisture close to that level.  It’s too low to support high t-storms.  If this dryness were at 700mb (10000 feet) vs 800mb it might actually support T-storms by evaporative cooling.  Another limiting factor is the lapse rates as mentioned in the AFD.  L57 in the skew-t is 4.3 C/km.  This means that for every kilometer air travels between 700mb and 500mb, the air cools  4.3C.  The “thermodynamically expected” rate is 9.8C/km and is defined by physics. It is known as the “dry adiabetic lapse rate”.  The closer to or above 9.8 (or 10) the L57 is – the more likely instability will allow for thunderstorms to form.  Today’s value is 4.3, sort of low to mid.  It isn’t helping the t-storms form.

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About browardwx

Weather nut.
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