The last week of the 2015 Atlantic hurricane season is here. In rare November fashion Hurricane Kate formed earlier this month over the open north Atlantic. Since then there have been no areas of interest in the Atlantic Basin. Only 16 named storms have formed from November 21st to November 30th since 1851 so the odds are high November 2015 will wrap up next Monday with no more named storms.
On Monday we are tracking two frontal boundaries in the Atlantic but there are no tropical waves. The strongest cold front of the season races out to sea in the western Atlantic. Another stalled boundary and upper level trough sits in the open central Atlantic. There is some scattered convection along this boundary but subtropical/tropical development is not expected at this time.
Officially no tropical depression development is expected over the next 5 days. With that being said models like the Euro and GFS still attempt to spin up weak low pressure northeast of the Bahamas later this week under a weakness in north Atlantic high pressure. This low would race northeast and could bring some squalls to the Canadian Maritimes over the weekend.
With less than 2 weeks left in the 2015 Atlantic hurricane season it’s no surprise that the entire Atlantic basin in generally quiet. Water temperatures are cooling and wind shear values are enhanced as fronts whip through the Gulf and Atlantic. Only 20 named storms have formed from November 11-20 since 1851 in the Gulf, Caribbean and Atlantic. The graphic below is courtesy Google Earth.
There is one area of interest in the Atlantic Tuesday. A weak area of low pressure drifts west in the southwest Caribbean. It combats moderate wind shear and will move over central America mid-week so the odds of tropical depression development are highly unlikely. None of the reliable computer models hint at tropical cyclone development over the next 5 days.
The 2015 El Niño event made history Monday. Weekly sea surface temperatures in the equatorial Pacific surpassed values set in the record 1997-1998 El Niño event. Sea surface temperatures climb to 5.4 degrees Fahrenheit above average in the central Pacific. In late November 1997 sea surface temperatures in this region peaked at 5 degrees Fahrenheit above average. With just one week of data it’s too early to say if the 2015 El Niño has peaked and will gradually start to weaken. The Climate Prediction Center says El Niño will likely peak during the 2015/16 Winter in the Northern Hemisphere. This pattern is set to bring an active and wetter than normal winter to the South with spells of possible severe weather/enhanced tornado threat in Florida. With more storm systems it will likely be cooler than normal with more cloud cover. Meanwhile the northern tier of the country will likely see warmer than normal and drier than normal conditions this winter. The SST anomalies graphic below is courtesy the Climate Prediction Center.
El Niño strengthened during the 2015 Atlantic season and it’s no surprise that the number of named storms and hurricanes is below average. If the season wrapped up today there would be 11 named storms, 4 hurricanes and 2 major hurricanes. In an average Atlantic season there are 12 named storms, 6 hurricanes and 3 major hurricanes. Meanwhile it was a blockbuster season for the east Pacific. In late October category 5 hurricane Patricia became the most powerful tropical cyclone ever measured in the Western Hemisphere with maximum sustained winds of 200 mph and a central pressure of 879 millibars. Both seasons end on November 30th.
Kate becomes the 4th hurricane of the 2015 Atlantic hurricane season Wednesday morning. In rare November fashion Kate is the first November hurricane in the Atlantic basin since Tomas in 2010. On average the 4th hurricane of the Atlantic season forms on September 21st. Despite increased wind shear over the past 24 hours Kate holds its own Wednesday. As of 11 AM max sustained winds top out at 75 mph at it races east-northeast out to sea at a swift 45 mph. Enhanced satellite imagery shows Kate begins to feel the effect of cooler north Atlantic waters as cloud tops are warming (even since early Wednesday morning). As it merges with a frontal system (nor’easter) over the next 24 hours it will become post tropical by Thursday morning.
Here is the National Hurricane Center’s 11 AM advisory. An extratropical Kate may bring squalls to the United Kingdom later this weekend.
Between cooler sea surface temperatures and increased wind shear Kate will lose its tropical characteristics by Thursday morning. While Kate combats 40-50 kt shear Wednesday morning these values climb to an extreme 60-80 kts late Wednesday and Thursday morning.
It may be the last month of the Atlantic hurricane season but we have a healthy and strengthening tropical storm Kate on our hands in the western Atlantic. As of 10 EST Kate is on the verge of becoming a hurricane with 70 mph sustained winds and it races northeast at 21 mph. Kate manages to maintain a well-defined central dense central overcast and Hurricane Reconnaissance Aircraft continues to find strong tropical storm force winds. Kate exited the northwest Bahamas Monday night and quickly accelerates out the sea Tuesday. It taps energy over the warm Gulf Stream under the influence of a front. Moderate and increasing southwest wind shear displaces some convection north and east of its center. These hostile upper level winds and cooler north Atlantic waters will eventually transition Kate into a post tropical system in about 36-48 hours. Kate will also deepen as a larger non tropical area of low pressure in the north Atlantic but poses to threat to land.
Below is the 10 AM EST forecast track. The NHC and computer models maintain category 1 hurricane strength until Kate fully transitions to a post tropical system by Thursday.
November named storms are rare and November hurricanes are even less common. If Kate becomes a hurricane it will be the first November hurricane since Ida in 2009. Since 1980 12 hurricanes have formed in the Atlantic Basin in November.
Tropical Storm Kate becomes the 11th named storm of the 2015 Atlantic hurricane Monday morning near the central Bahamas. Data from Hurricane Reconnaisance Aircraft show Kate continues to strengthen a bit and tropical storm warnings are in effect for the central and northwest Bahamas.. Max sustained winds top out at 45 mph at 10 AM EST. The center of circulation and the core tropical storm force winds will skirt the central Bahamas Monday and clip the northwest Bahamas Monday night. 1-3″ of rainfall is the primary threat. Kate is the first November named storm in the Atlantic basin since Subtropical Storm Melissa in late November 2013. November named storms are pretty rare. Only 5% of named storms form during the last month of the Atlantic hurricane season.
Here is the 10 AM EST track. Kate will safely pass east of the U.S. as it guided by a frontal boundary and will head northeast by Tuesday as it rides the perimeter of the Atlantic subtropical ridge. During this time the tropical storm will strengthen some between the Mid Atlantic region and Bermuda.
By mid-week Kate will merge with a larger stronger non tropical area of low pressure east of New England and south of the Canadian Maritimes. It will become post tropical by Thursday morning, if not sooner. Here is the Euro’s forecast Wednesday afternoon which shows the areas of low pressure combining.
Invest 94L organizes Saturday night and Sunday morning east of the Bahamas and north of Hispaniola. Convection is more concentrated southeast of Turks and Caicos and a tropical depression may be form soon. Water temperatures in this region are in the low to mid 80s, moisture is plentiful and wind shear overhead is low at 10 kts so further organization is possible. As of Sunday morning the odds of tropical depression development sit at 50% by Tuesday and 70% over the next 5 days. Early Sunday morning computer models suggest a west-northwest near or through Turks and Caicos and the Bahamas over the next few days. A northeast track is likely mid-week around a ridge of high pressure (guided by a frontal boundary) and the disturbance will likely combine with a front during this time. Invest 94L is no threat to the U.S. but will likely bring some squalls to Turks and Caicos and the Bahamas through early work week. Interest in Bermuda should keep an eye on Invest 94L.
The likely future track of Invest 94L coincides with November tropical cyclone climatology. A northeast track east of the U.S. and out to sea is expected. November named storms are rare but not non-existent. The last November named storm is subtropical storm Melissa in late November 2013.
As expected Invest 93L merged with a cold front in the Gulf of Mexico and tropical depression development is not expected. This area of low pressure will enhance rainfall/embedded thunderstorms in Florida and for parts of the Southeast as it slow drifts northeast over the next 24-48 hours.
The Atlantic Basin tries to come alive this weekend. There are still about 3 weeks left in the official 2015 Atlantic season. Convection increases near an area of low pressure in the western Gulf of Mexico but this low (now pinned Invest 93L) is broad in nature. There is only a small window for Invest 93 to gain tropical characteristics as it will likely merge with a cold front over the next 24 hours and drift east-northeast. Those odds sit at 20% over the next 2 days per the NHC. If convection increases a Hurricane Reconnaissance Aircraft may investigate Saturday afternoon.
While water temperatures still support tropical depression development in the western Gulf of Mexico upper level winds are less favorable for development. Wind shear over Invest 93L is moderate at 10-30 kts Saturday morning. These values increase Saturday night in the wake of a cold front to 40-50 kts+ making tropical depression development highly unlikely Saturday night and Sunday. Regardless of tropical depression development as low pressure merges with a cold front coverage of showers increases for parts of the northern Gulf coast and Florida late Saturday and Sunday.
For over a week now models have hinted that a tropical low may spin up near Puerto Rico or the Bahamas next week. That feature is still evolving near an area of disturbed weather near the northern Lesser Antilles Saturday. In a few days low pressure may try to close off near the Bahamas as a ridge of high pressure breaks down. Those odds sits at 20% over the next 2 days and 50% over the next 5 days per the NHC Saturday. The next named storm is Kate.
Here’s the 06Z GFS Tuesday evening. It develops a closed low north of the Bahamas that eventually deepens further and races northeast over the open Atlantic Wednesday and Thursday. Water temperatures in this region of the Atlantic have obviously cooled and so the time frame full-blown characteristics drops off mid to late work week. The Euro hints a similar setup but doesn’t really deepen low pressure until late Wednesday or Thursday and at this point it is south of the Canadian Maritimes.
As is often the case in early November most of the Atlantic Basin is nice and quiet Wednesday.The same tropical wave we’ve been tracking for a few days is now making its way westward through the Caribbean bringing pockets of showers and storms to Hispaniola. A strong ridge keeps the Gulf and western Atlantic stable with no areas to watch. No tropical depression development is expected through the weekend but models try to stir something up east of the Bahamas and north of Puerto Rico early next week.
Both the Euro and GFS show a ridge of high pressure breaking down in the Atlantic over the weekend. Both models are on board with low pressure spinning up north of Puerto Rico early next week. The graphic below shows each models solution for next Tuesday afternoon. If a tropical cyclone forms in November it typically forms in the western Atlantic and heads northeast and away from the U.S. That will likely be the case if a named storm (Kate) forms early next week. Interest in Bermuda should keep a watchful eye. The last November named storm was Tropical Storm Melissa in 2013.
The last month of the 2015 Atlantic season is here. Since records go back to 1851 only 35 named storms have formed from November 1st through November 10th in the Atlantic Basin. Most of these formed in the western Caribbean or western Atlantic. Activity steadily declines through the month as water temperatures cool. Not to mention wind shear values rise at times too as fronts whip through regions of tropical development. The graphic below is courtesy Google Earth.
There is only one tropical wave in the entire Atlantic Basin Monday. It is embedded in a belt of high westerly wind shear just east of the Lesser Antilles. It will stay disorganized but a few showers will make it to the eastern Caribbean. The other feature of note is a frontal system along the northern Gulf coast. At the tail end of this boundary there is a burst of scattered convection in the Bay of Campeche. As this boundary washes out over the next few days scattered showers and storms will continue in the central and southern Gulf but they will stay disorganized. Officially no tropical depression development is expected over the next 5 days.
Fast forward 7 days to next Monday and the Atlantic Basin looks to stay quiet, at least according to the European model. A strong ridge stays firmly in place in the Atlantic. The long-range GFS breaks down this ridge early next week. It hints that low pressure may spin up north of Puerto Rico next Tuesday and lift north.
It’s safe to say the 2015 Atlantic winds down with no areas of interest on the horizon. An upper level ridge is firming in place in the Gulf and Caribbean. Water temperatures are cooling a bit and upper level winds remain hostile with active fronts. October wraps up Saturday and its been a quiet month overall in the Atlantic Basin. The last named storm, Joaquin, dissipated in early October. While only 17% of named storms form in October even fewer form in November (especially during a strong El Niño year). Only 5% of named storms form during the last month of the Atlantic Hurricane season. Here’s the very quiet enhanced satellite imagery Saturday morning. There is only one weak tropical wave in the central Atlantic between the Lesser Antilles and Africa.
During November any named storms that do form typically develop in the northwest Caribbean or southwest Atlantic near the Bahamas and drift northeast under the influence of frontal boundaries and troughs.
None of the reliable computer models develop anything tropical in nature in the Gulf, Atlantic or Caribbean over the next 5 days and beyond. Here is the Euro on Thursday morning. A non tropical low races northeast over the open north central Atlantic but that is the only feature of note. High pressure remains in control which means the Atlantic basin stays quiet.