2:15 PM (Friday) | ***Hurricane “Isaias” to significantly impact the Bahamas, southern/eastern Florida and likely have quite an impact up along the rest of the east coast***

Hurricane “Isaias” is a rather large storm system (lower, right) and continues on a NW track on Friday afternoon. This system will significantly impact the Bahamas over the next 24-48 hours as well as the southern and eastern parts of Florida. The heavy rainfall associated with Hurricane “Isaias” may then ride up along the rest of the US east coast ultimately resulting in a significant rain event all the way from Florida to eastern New England. Satellite images courtesy NOAA/NESDIS

Overview

“Isaias” became the second hurricane of the 2020 Atlantic Basin tropical season in the overnight hours as it pulled away from the island of Hispaniola and out over the very warm waters of the southwest Atlantic Ocean. The 2020 Atlantic Basin tropical season has gotten off to a very active start - now with nine named systems – and it will very likely remain quite dynamic as we begin the month of August.  In fact, a couple other tropical waves are now churning over the eastern and central tropical Atlantic - virtually guaranteeing the energetic season will continue in coming days.  Hurricane “Isaias” is likely to continue on a NW track over the next 24-36 hours that will bring to a position just off the east coast of Florida this weekend with significant impacts to the Bahama Islands and southern/eastern Florida.  “Isaias” is now classified as a category 1 hurricane and there is a chance it intensifies to a category 2 storm before it makes its closest approach to Florida’s east coast.  After that, “Isaias” may very well ride up along the east coast ultimately resulting in a significant rain event all the way from Florida to eastern New England.

A compilation of 12Z Friday computer model predicted storm tracks for Hurricane “Isaias” in coming days. Map courtesy weathermodels.com (Dr. Ryan Maue, Twitter, UKMET, CMC, NOAA)

Details

At 2 PM, Hurricane “Isaias” has a central pressure of 991 millibars, maximum sustained winds of 75 mph, and continues to move along at a pretty good clip in a northwesterly direction (305 degrees) at 16 mph. “Isaias” was classified as a tropical storm throughout the day on Thursday while it interacted with the island of Hispaniola and its intensification was rather limited due to the disruption in its circulation field by the mountainous terrain.  Once the tropical storm left the island in its wake, however, “Isaias” did strengthen into a category 1 hurricane becoming the second of the 2020 Atlantic Basin tropical season (the other being “Hanna” which came ashore just last weekend in southern Texas). 

Latest radar echoes feature an “eyewall” on the north side of Hurricane “Isaias” likely restricted to that quadrant at the current time because of the southwesterly vertical wind shear.

Hurricane “Isaias” is currently situated in an environment that features some dry air and southwesterly vertical wind shear which is inhibiting additional intensification in the short-term. Latest radar echoes show Hurricane “Isaias” features an “eyewall” on its northern side only and that is likely due to the wind shear. This “eyewall” may begin to expand to the west side of the developing circulation center as the hurricane moves into an environment with more favorable conditions in terms of wind shear.

Sea surface temperatures are very warm in the southwest Atlantic Ocean as we end the month of July and are sufficient to support a “major” hurricane with some spots over 30°C. Map courtesy weathermodels.com (Dr. Ryan Maue, Twitter), NOAA

As Hurricane “Isaias” pushes farther away from Hispaniola today and out over the very warm waters of the Gulf Stream where sea surface temperatures exceed 30°C, it is conceivable that it strengthens into a category 2 hurricane with an outside chance at attaining category 3 (“major”) status.  Hurricane “Isasis” is likely to continue on the same NW track for the next 24-36 hours as it remains influenced by the periphery of a high pressure system parked over the western Atlantic.  After that, Hurricane “Isaias” will likely begin a gradual turn to the north-northwest and then to the north as an impressive upper-level trough “digs” into the southeastern US.  The combination of the upper-level trough to the west and high pressure to the east will allow for “Isaias” to potentially ride up along the east coast early next week passing over eastern North Carolina possibly as a hurricane in the Monday time frame. After that, the remains of “Isaias” should then move to the coastal sections of the Mid-Atlantic region and eastern New England in the late Monday night and Tuesday time period. As is often the case with tropical systems, they tend to accelerate as they get to higher and higher latitudes.

The 12Z high-resolution version of the NAM (3-km) predicts highest wind gusts associated with Hurricane “Isaias” over the next 60 hours will stay just off the east coast of Florida. Map courtesy Weather Bell Analytics at weatherbell.com, NOAA

The latest water vapor imagery (not shown) indicate very high levels of moisture now engulf the storm system and this will be contributing factor to very heavy rainfall in the Bahama Island chain during the next 24 hours to include flash flooding. Heavy rainfall should begin to affect southern and eastern Florida by tomorrow morning and will likely continue through tomorrow night.  The heavy rainfall associated with “Isaias” is then quite likely to push up along the eastern seaboard late in the weekend and early next week - first into the eastern Carolinas, then to the Mid-Atlantic coastal sections, and finally to eastern New England.  Winds reaching hurricane-force are likely in portions of the Bahamas from later today into tomorrow and tropical storm or hurricane-force winds can impact Florida’s east coast beginning on Saturday and continuing through tomorrow night.

The latest “official” map by NOAA’s National Hurricane Center of tropical cyclone locations features two waves in the central and far eastern tropical Atlantic Ocean (each marked with an “X”). Map courtesy NOAA/NHC

Stay tuned…there are still some details that have to to be ironed out regarding the strength and ultimate track of Hurricane “Isaias”. One final note, the next named tropical storm in the Atlantic Basin would be “Josephine” and that could happen much sooner than desired given the level of activity in the central and eastern tropical Atlantic.

Meteorologist Paul Dorian
Perspecta, Inc.
perspectaweather.com

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