Strong Wave Near the Yucatan Peninsula Soon to be "Karen"....... Weakening "Jerry" Far Out in the E. Atlantic.....
Sea surface analysis below. The numbers show the wave heights with the highest numbers closer to the tropical disturbance. Higher waves/rough seas & surf & a high rip current risk will reach the Fl. Panhandle coast Fri. & especially over the weekend. Wave heights of at least several feet near the First Coast are courtesy the recent long term pattern of east/northeast winds which will change over the weekend -- becoming more southerly or even southwest by Sunday.
Satellite imagery above shows the active tropical wave
continuing to move slowly northwest through & near the Yucatan Channel. A slight turn to the north was noted overnight. Convection is strong with cold cloud tops. Hurricane hunter aircraft measured winds of 30+ mph Wed. afternoon & another plane this (Thu.) morning has found even stronger winds -- nearing 60 mph -- & lower surface pressure.
The wave has been in an area of relatively low wind shear but is already showing signs of feeling the effects from increasing west/southwest shear as the bulk of the convection is over the eastern semicircle of the wave. Shear will increase even more through the weekend which should limit the ultimate intensity as well as keep the system heavily weighted on the east side (heavy t'storms near & east of whatever center might develop). While water temps. are more than warm enough to support tropical development, there are significant deterrents: (1)
very dry mid & upper level air (as can be seen on the water vapor image below) over Mexico & virtually all of the Western Gulf of Mexico. This dry air will stay adjacent to the wave for its entire life cycle. Any development of the wave would likely only encourage this dry air to flow into a possible surface system (low) [due to a clockwise circulation of the system].(2)
the moderate to quite strong shear over the Northern & Central Gulf of Mexico.One caveat is the approach of an upper
level trough this weekend that's moving into the Eastern U.S. This trough might help to "ventilate" the wave ("Karen"?) upon approach to the Gulf Coast which could compensate for the increasing shear thereby maintaining the tropical storm (assuming that's what this wave becomes). The timing & how far south this upper trough digs will be the main driver for the track of the wave. A weak & transient upper level ridge will build north & northeast of the tropical disturbance over or near Georgia. As the trough approaches, the ridge will collapse paving the way for the northeast acceleration of the wave Sun.-Mon. The system will then become attached to a cold front & absorbed by the upper trough over the Eastern U.S.
The GFS forecast model remains the strongest with moderately strong tropical storm moving inland near Pensacola early Sun. The European forecast model continues to be weaker & farther west but ultimately brings the system ashore at about the same time -- early Sun. -- & only a little farther west thanks to a pretty sharp turn to the northeast in response to the approaching upper level trough (which is a little stronger & a little farther south on the model). Overall....these 2 models -- which I favor to forecast the tropics with -- along with most of the other global forecast models have come into pretty decent agreement on track & timing.
So.... looks like the tropical disturbance will move to the Gulf Coast somewhere between approximately
Pascagoula & Apalachicola about
Sunday morning. If traveling this weekend west to the Fl. Panhandle &/or coastal Mississippi/Alabama, stay up to date on this system. Heavy rain & gusty winds....& possibly isolated tornadoes.... will be most significant from about the Fl. Big Bend across the Panhandle to as far west as just east of New Orleans. And, of course, remember that the ultimate track & intensity is subject to change(!).FOR THE FIRST COAST:
-- given the current forecast thinking/reasoning, impacts will be relatively minor
-- Sat. is fine....showers & scattered t'storms will increase midday Sunday through Sun. night
-- could be a very isolated threat for tornadoes favoring western parts of the viewing area (Lake City to Waycross)
-- some heavy rain but speed of the system + a track well to the west/northwest of Jax should limit the overall amounts -- perhaps an average of a half inch to inch, locally 1-2" especially west & northwest of Jax.
-- breezy Sunday-Sun. night & to some degree Mon. but not overly strong averaging 15-25 mph.
-- somewhat rough seas & surf Sunday-Mon. but again relatively minor. An offshore component to the winds will make for happy surfers(!).
The image below shows the moderate to strong -- 20-30(+) knots -- over much of the Gulf of Mexico.
Water vapor satellite image showing the very dry air in close proximity to the disturbance:
Model plots below courtesy S. Fl. Water Management District:
The map below is courtesy NOAA & shows the typical genesis regions for tropical development during the first week of Oct. The wave moving into the Gulf of Mexico is in a sort of "sweet spot" climatologically.
We'll also need to monitor the Caribbean in about 10 days to 2 weeks for the possibility of renewed tropical development.
"Jerry" remains a "nonissue" far out in the open E. Atlantic soon to accelerate to the northeast & become a remnant low.
Tropical waves continue to decrease as they move off the coast of Africa. We should be able to close the door this season on any long track Cape Verde storms.