Weak "Karen" Beginning Turn to the North.......
FOR THE FIRST COAST: (our weather (forecast/effects) changes very little even if "Karen" dissipates as a plume of tropical moisture will spread across the area. The moisture + an approaching cold front will combine for rain & storms into Mon.)
given the forecast thinking/reasoning (as discussed below), local impacts will be -- generally -- pretty minor....as I've tried to articulate for the last 5-6 days.
** Scattered showers & a few t'storms will develop Sunday through Sun. night, but the day will not be a washout with only some brief heavy rain in some spots. Rain & storms will increase Monday.
** still an isolated threat for tornadoes Monday given the combination of Karen's remnants, a cold front, a strong upper level trough + some surface heating.
** some heavy rain but speed of the system should limit the overall amounts -- perhaps an average of a half inch to 1.5", locally 2"+ with most of the heavy rain occurring Monday.
** breezy Sunday through Mon. but not overly strong averaging 15-20 mph. Stronger t'storms may produce winds nearing 50 or even 60 mph but only in isolated cases.
** somewhat rough seas & surf Sunday-Mon. but again pretty minor. An offshore component to the winds by later Mon.-Tue. will make for happy surfers(!).
While the "fat lady" isn't singing yet when it comes to the demise of "Karen", she's starting to clear her throat(!).
Infrared satellite below shows strong convection way to the east of the center.
The visible satellite below nicely shows the center of the circulation removed (to the west/northwest) from the intense convection that remains heavily weighted on the east side of the circulation.
While there has been -- & will be -- bursts of convection, it's doubtful that the center can ever truly become imbedded underneath the strong convection thereby allowing the mid level & low level center to become stacked. In fact, indications from hurricane hunter aircraft are that midlevel center is weakening which was still going strong through Sat. morning.
Sea surface analysis below. The numbers show the wave heights with the highest numbers closer to "Karen", of course. Higher waves/rough seas & surf & a high rip current risk will affect the Fl. Panhandle coast through the weekend. Wave heights will not be significant for the First Coast.
Satellite imagery shows "Karen"
struggling thanks to persistent moderate west/southwest shear. The center remains displaced to the west of the strong convection as mentioned above. The track has generally been a little west of earlier forecasts due to the shallow nature of the system but a pretty sharp right hand turn (to the northeast then east) will occur as a strong upper level trough & surface cold front approach.
Water temps. are more than warm enough to support a tropical cyclone, but the shear as well as dry air will be something "Karen" will not likely be able to overcome. Some slight organization is possible upon approach to the Fl. coast due to interaction with the cold front & approaching upper level trough. The primary elements limiting "Karen" (& will continue until landfall): (1)
very dry mid & upper level air (as can be seen on the water vapor images below - the black & rust color) over Mexico & virtually all of the western half of the Gulf of Mexico extending north into the Southern U.S.(2)
the moderate to quite strong shear over most of the Gulf
As the upper trough approaches, an upper level ridge near Jacksonville will collapse paving the way for the east then northeast acceleration of "Karen" Sun. night-Mon. night. The remnant low will become attached to the cold front & become absorbed by the upper trough over the Eastern U.S. The timing -- landfall -- of "Karen" has generally slowed. After brushing the southeast tip of Louisiana, the low should turn sharply east reaching the Fl. Panhandle or Big Bend Mon. Any jog to the north would take the low inland along the Gulf Coast.
Virtually all global forecast models are now keeping "Karen" weak with a move very near the southeast tip of Louisiana through early Sun. moving parallel to & just offshore of the Gulf Coast Sun.-Sun. night into Mon. morning.
So.... what didn't ever look like a major storm for the Gulf Coast will be even weaker. And what I termed as "fringe effects" from the storm for the First Coast will still be valid thanks to the tropical moisture & cold front.
There will still be heavy rain along the Gulf Coast Sun.-Mon. & over Fl. later Sun. night into Mon. with at least some severe storm threat as well.
The image below shows the moderate -- 20(+) knots -- over a good portion of the Gulf of Mexico.
Water vapor satellite images below showing the vast area of very dry air in close proximity to "Karen":
Model plots + radar imagery (with projected track of "Karen") below courtesy S. Fl. Water Management District:
3-day total rainfall forecast:
The satellite imagery below shows the mature powerful upper level storm system over the Central U.S. that's driving the cold front eastward (note t'storms north-south along the front) which will eventually turn "Karen" -- or its remnants -- east & northeast.
Tropical waves continue to decrease as they move off the coast of Africa. This late in the season, development -- or at least long track tropical cyclones across the Atlantic -- is not likely so deep in the tropics. Still...these waves would have at least some potential for long term development if they can get across the Atlantic near the Caribbean &/or SW Atlantic. There are indications of long term development in or near the Caribbean & SW Atlantic in roughly 10 days to 2 weeks.