"Isaac" Remnants into Ohio & Tennessee Valley; "Leslie" Battles Shear But Still Producing Intense Thunderstorms...T.D. #13 Develops in E. Atlantic...........
The remnant low/upper level disturbance that was "Isaac" is moving southeast in the Ohio Valley & turning south toward the Tennessee Valley. Forecast models show the mid & upper level disturbance maintaining itself & dropping south/southeast then south across the Eastern & Southeast U.S. this week reaching the Gulf Coast mid to late week(!). "Ivan" made a somewhat similar loop in 2004 (see 4th & 5th images below). It doesn't appear a surface low will accompany the disturbance, but the upper level energy could enhance showers & t'storms mid to late week. However, the European forecast model does now develop a surface reflection (low pressure) in the Northeast Gulf of Mexico Thu.-Fri., so this situation could become interesting. Based on history ("Ivan" in 2004), if another storm were to develop & could be traced to what was "Isaac", if the new low became a tropical cyclone, it would again be named "Isaac". Click
here for updated storm summaries on 'Isaac" from the Hydrometeorological Prediction Center.
IVAN'S TRACK IN 2004:
"Leslie" has been putting up a good fight against moderate shear
& -- so far -- has had no problem surviving as a "blob" of intense convection. There has been a recent trend of banding features on satellite data. Strong shear & some dry air will hammer away at the cyclone the next few days as "Leslie" is sandwiched between a compact but strong upper low in the Bahamas & an upper level trough to Leslie's northeast over the Central Atlantic. Shear will relax starting midweek which could allow for significant strengthening. The upper level trough tugging "Leslie" north/northwest now will not entirely pick up the cyclone leaving "Leslie" in a weak steering flow midweek which will cause the storm to stall at or just north of Jacksonville's latitude in the Central Atlantic. There could be some jog west at that point but early indications are that "Leslie" will still get steered north then northeast in time. Still a long way out with plenty that can change. And if we look at the W. Pacific last week, the 2nd typhoon moved to the China coast west & southwest of Japan, so we'll have to beware of a farther west track in the long run than forecast models are currently indicating. All will hinge on the timing & intensity of what looks to be a strong upper level trough that will dig into the Eastern U.S. late this week into the weekend. "Leslie" should start to increase its forward speed to the north or north/northwest as the trough approaches. This move north could be helped by an upper low near Florida as the upper low moves east/northeast, though -- in the long run -- the expansive "Leslie" circulation could end up absorbing the upper low.
In any case... "Leslie" should be strong enough & large enough to send an easterly swell to First Coast beaches this week increasing the rip current risk.
Tropical depression #13 has been declared in the E. Atlantic. This satellite-derived system is tiny & will move north then northeast with no land to be impacted.
A wave in the far E. Atlantic well south of t.d. #13 has recently flared up. This wave will move just about due west the next few days. Other waves will start to come off Africa with renewed vigor by the weekend into next week.
