"Isaac" Near Hispaniola - Tropical Storm WARNING, Hurricane WATCH S. Fl. & Keys; Strong Wave Off Africa..........."Isaac":
** No significant direct impacts on the First Coast through Sat. & most of Sunday other than some increase in onshore flow by later Sunday, an elevated rip current risk at area beaches & an easterly breeze..........
** If planning travel between now & next week to the Caribbean, S. Fl., Bahamas, Keys or Gulf Coast, stay alert to the latest forecasts...........
** Stay calm but alert & organized...review hurricane prep's...& any necessary flood mitigation plans.
*** DON'T LET "ISAAC FATIGUE" GET THE BEST OF YOU THIS WEEKEND -- STAY UP TO DATE ON THE LATEST FORECASTSIF
the current forecast path proves accurate, First Coast impacts would be primarily heavy rain & isolated tornadoes(highly dependent on strength, speed & exact location -- changes are likely - stay up to date & plan accordingly) - ONE SHOULD EXPECT THE FORECAST TO CHANGE TO AT LEAST SOME DEGREE!:
-- onshore east winds begin to increase some Sunday causing rougher seas & surf & a rip current risk at area beaches
-- showers & storms begin to increase Sun. & especially Mon.-Tue. possibly lingering into Wed. With "Isaac" to the west, a slug of tropical moisture will push northward & bring potentially heavy rain at times.
-- the greatest First Coast threat
would be possible flooding (especially since the ground is saturated & streams & rivers are already running high) & isolated tornadoes.
-- a track more west decreases these threats....a track more east increases these threats & introduces more wind....a track far to the east greatly minimizes most threats though "Isaac" east of Jacksonville seems very unlikely.
"Isaac" has made the turn more northwest, maybe even a little north & slowed some. The storm steadily increasing Fri. evening with an eye feature evident in satellite & radar imagery right before landfall on the "claw" of Haiti. The "shear zone" (see the 3rd image below) persists north of "Isaac" but should weaken as a trough low pressure lifts out to the northeast. In advance of "Isaac" is very warm ocean water with deep oceanic heat content & less shear (this is especially true near the Fl. Straits & near Cuba) once past Sat. Any land interaction through the weekend will be a major factor in intensity in what otherwise will be an increasingly favorable environment. Hispaniola in particular is well known for shredding apart tropical cyclones though it's looking like the center may not spend a lot of time over Haiti. Mountains over Eastern Cuba are as high as 10,000 ft., so it's likely that some degradation of the storm will occur depending on how far inland the center progresses over Cuba. Of potentially greatest concern is -- once past Hispaniola & Cuba & if the structure stays intact -- a slower movement over the Fl. Straits & SE Gulf of Mexico where conditions look especially ripe for a hurricane & shear is much lower (strong shear now over the Gulf is forecast to weaken by early next week). It's notable that most forecast models have been accurate so far in depicting only slow strengthening -- or a steady state -- up to this point. It's near & north of Cuba when more significant strengthening is forecast & more likely to occur. The 2nd map below shows tropical cyclone heat potential - brighter the colors, the more deep, warm ocean water potentially available to a tropical cyclone. A relatively cool area exists just northwest of Cuba, but the Eastern Gulf has pretty high potential until the far Northern/Northeast Gulf.
As for track....a generally northwest movement should continue before there's enough weakening in the upper level ridge north of "Isaac" + a deep enough of a tropical cyclone -- to allow for a northward move of some sort. In addition, the fast forward movement implies little chance/opportunity for an abrupt turn to the north. The mountainous terrain of Cuba &/or Hispaniola could affect movement for a short while as will "organization mode" & bursts of convection. The GFS has generally remained consistent on a west/northwest track that takes "Isaac" very near Fl. but has also shifted a little to the east recently & -- in recent model runs -- has been a little "jumpy". But the overall consistency + a pretty good track record so far this season is reason to favor the GFS. The European has trended stronger but still farther west than most other models before the northward turn & is also slower though is coming more in line with the GFS on timing in particular. The European has not had a very good tropical season so far despite good performance in previous years (some adjustments were incorporated into the model during the past year). In other words, "you ride the hot horse" (at least for now!). Forecast models as a whole have again shifted a bit west with virtually all global models showing an eventual U.S. hit ranging from east of New Orleans to Florida anywhere from Sun. night to late the middle of the week.
NOAA began high altitude G4 (jet) surveillance Thu. & the data was used in the forecast models beginning Thu. evening & will hopefully help with the forecast track & lead to better model consistency & uniformity. I've noticed that sometimes it can take several forecast cycles before this new data is effectively smoothed by the model's complicated numerical prediction equations. Nonetheless, it is looking increasingly likely that the U.S. will be impacted in some way, shape or form in due time.
But any direct impact on the U.S. should hold off until late in the weekend for S. Fl. though heavy rain will already occur Sat. due to tropical moisture spreading northward. The storm brought gusty winds & some heavy rain to Puerto Rico & is moving away from the island though heavy rain will continue into early Sat. Hispaniola & Cuba will be impacted into the weekend with what will likley be major flooding. No direct effect on the First Coast through at least Sunday though onshore flow will increase some later Sunday along with bands of showers moving west/northwest off the Atlantic. Anyone traveling to the Caribbean, Bahamas, Keys &/or S. Fl. should stay tuned to the latest forecasts.
The large wind field -- tropical storm force winds extending 230 miles to the north of the center -- has required the early issuance of tropical storms WARNINGS & hurricane WATCHES for S. Fl. & the Keys.
** An interesting possible teleconnection can sometimes be used by observing the W. Pacific. There are twin typhoons (3rd satellite image below followed by track maps/forecasts). -- Intense typhoon "Tembin" hit Southern Taiwan Thu.-Thu. night & is slowing & forecast to do a loop. A second typhoon -- "Bolaven" is to the storm's east & is forecast to steadily march northwest & move south of Japan eventually into China.
In the Atlantic Basin...."Isaac" could end up being a slow moving storm in the long run & become erratic next week as steering currents collapse or at least become weaker (similar to "Tembin"?)...while "Joyce" (now only a remnant low)gradually turns more northwest then north over the open Atlantic in the long run then sharply northeast (though early in the game on that one).
This struggling system has become a remnant low though could regenerate next week. Recurvature into the open Atlantic is likely but when may end up depending on how quickly the storm deepens (or not) & continuing interaction with "Isaac" & an upper level low. No effect on the U.S. but there may be some heavy rain & gusty winds in Bermuda early in the upcoming week.
Yet another wave has come off the coast of Africa with the potential for some development as it moves west. At least some upper level ridging will rebuild across the Northern Atlantic in about 10 days, & the extent of this ridging (Bermuda high) will have a lot to do with how far west across the Atlantic this wave might go. Some long range global forecast models do show a system approaching the Western Atlantic & maybe as far as east of the Bahamas or so in roughly 10 days (late Labor Day weekend).
The active tropics come at a time notorious for big hurricanes.
It was nearly a year ago then "Irene" hit the upper east coast of the U.S. & 20 years ago (Aug. 24th) that powerful Cat. 5 "Andrew" smashed into S. Fl. "Andrew" changed the way Fl. -- especially S. Fl. -- builds homes. And it changed lives forever. I spent some time in the Miami & Homestead area in the spring working on stories about "Andrew, 20 Years Later" -- click here
to see the stories. Click here
for an excellent Miami N.W.S. web article/discussion/video of "Andrew". Images below are courtesy NOAA & AOML.
Metro PCS offers these tips on keeping your cell phone charged during storms:
· Choose texting over dialing: Text with family and friends and limit calls to emergencies to save the battery life. “Keeping multiple browser windows open can significantly drain battery power,” says Möller.
· Keep key numbers handy: Program emergency phone numbers in your phone, including local police, fire department, insurance providers, power companies, friends and family. “Make sure these numbers are labeled under names that younger family members will recognize to make for easy, quick calling,” Möller says.
· Have a back-up: Make sure back-up power devices are available at all times, such as a car charger.
· Charge it: Make sure you keep cell phone batteries fully charged well before warnings are issued.