****Hurricane Isaias is likely to intensify next 24 hours or so...can make landfall early tomorrow night somewhere near Mobile Bay...impacts all the way to Ohio Valley, Mid-Atlantic, NE US****

Hurricane Isaias continues to churn to the east-northeast at this hour, but a turn to the north will take place on Friday as strong high pressure ridging builds in over the western Atlantic. Images courtesy NOAA/GOES East

Overview

The eastern Pacific Ocean is alive and well with tropical activity and now the Atlantic Basin has its first hurricane of the season which is the latest for the first hurricane in more than one hundred years. Hurricane Isaias is now pulling out of the southwestern Gulf with maximum sustained winds of around 80 mph (category 1). It is likely to intensify during the next 24 hours or so into a category 2 storm with an outside chance of climbing to “major” category 3 status. There can be some weakening in the hours before landfall which is likely to be around early Friday night and somewhere near the Mobile Bay region of the central Gulf coast. After landfall, impacts of Isaias will continue to the Tennessee and Ohio Valleys on Saturday and all the way to the Mid-Atlantic and Northeast US on Sunday where rain is likely and it can be heavy at times. Meanwhile, Tropical Storm Rachel will make a dramatic right turn and bring rain and wind to southern California and northern Baja, and its vast moisture field will push all the into the northern Rocky Mountain States where it may be cold enough to produce accumulating snow. Tropical Storm Simon is likely to become a hurricane and turn into Mexico with its moisture field likely headed to the southwestern and south-central states.

Hurricane Isaias can intensify during the next 24 hours or at least to a category 2 storm and there is an outside shot at of it attaining “major” category 3 classification. Landfall is likely around early tomorrow night in the Mobile Bay region of the central Gulf coast. Map courtesy NOAA/NHC

Atlantic Basin…Hurricane Isaias

There was hope that we could get through the entire Atlantic Basin tropical season without a hurricane, but our luck has run out here in early October and we now face the threat of a direct hit in the central Gulf by early tomorrow night. A tropical system over the very warm waters of the southwestern Gulf of America has reached classification as a hurricane with maximum sustained winds of 80 mph (category 1). In fact, favorable environmental conditions raise the risk of intensification into category 2 classification during the next 24 hours or so, and a “major” hurricane classification of category 3 cannot be completely ruled out.

The storm surge will likely be significant across portions of the central Gulf coast associated with the arrival of Hurricane Isaias. Map courtesy NOAA/NHC

The favorable environmental conditions that support intensification of TS Isaias include very warm sea surface temperatures (30-31 degrees Celsius), plenty of moisture, and only light to moderate wind hear in the immediate vicinity of its core center. Having said that, there are some signals that vertical wind shear can increase in the final hours before it reaches the central Gulf coast late Friday or early Saturday.  Hopefully, this will take place which could cause some last-minute weakening of Isaias, though it looks likely that it will be a significant hurricane when it reaches the central Gulf coast...perhaps right near Mobile Bay.

Wind gusts could remain “damaging” o Saturday all the way into the Tennessee Valley as the remnants of Hurricane Isaias push to the north/northwest. Map courtesy NOAA, Weather Bell Analytics (Meteorologist Joe Bastardi, X)

After landfall, the impact of Isaias is likely to last well to the north of the Gulf coast with the remnants of Isaias pushing to the Tennessee Valley. Winds gusts can continue to remain very high and potentially damaging all the way into the Tennessee Valley as an interaction with an upper-level jet streak will maintain a very unstable environment surrounding Isaias. As a result, power outages are certainly on the table from the central Gulf coast region to the Tennessee Valley. Severe weather is also a threat from late Friday night through Saturday; especially, on the right side of the northward-moving system with isolated tornadoes on the table (e.g., in portions of Alabama, Georgia and Florida). There certainly can be some impact on college football games on Saturday; especially, in Southeastern Conference locations.

By Sunday, the impact of Isaias will extend all the way north and east to the Mid-Atlantic region and Northeast US where rain and wind could close out the weekend. Some of the rain that falls up north can be heavy and a few thunderstorms can mix into the picture. Overall conditions should improve on Monday as the remnants of Isaias push off the Mid-Atlantic/NE US coastline.

Two Tropical Storms in the eastern Pacific, Rachel and Simon, could bring significant amounts of moisture into the western US in coming days. Map courtesy NOAA/NHC

Pacific Ocean…Tropical Storms Rachel and Simon

In the eastern Pacific Ocean where tropical activity has been high this season, Tropical Storm Rachel continues to churn in a seemingly harmless west-to-northwest direction over some very warm waters where temperatures have been boosted by a very strong El Nino. This tropical storm is likely to take a dramatic turn tomorrow from a west-northeast trajectory to northeast, likely bringing it near northern Baja California by late Saturday, and this will send plenty of rain and wind into southern California as well as Baja.

Tropical moisture from Tropical Storm Rachel may makes its way all the way to the northern Rocky Mountain States where enough cold air could be around to help produce accumulating snow. Map courtesy ECMWF, tropcialtidbits.com

After that, the moisture field associated with the remnants of Rachel will push into the interior western US, perhaps all the way to the northern Rocky Mountains States. In fact, the tropical moisture field of Rachel – now centered way down south over the eastern Pacific Ocean - could very well end up enhancing snowfall in places like Montana, Idaho and Wyoming by the end of the weekend or early part of next week...quite an amazing turn of events.

Meanwhile, a second tropical wave over the far eastern Pacific has intensified into named tropical storm status (called Simon) and it should reach hurricane level shortly...potentially even “major” categorization as a 3. This trailing system should veer into western Mexico by Sunday, and its moisture field can impact the southwestern and/or south-central states during the early part of next week.

Meteorologist Paul Dorian
Arcfield
arcfieldweather.com

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