July Starts on a Quiet Note in the Atlantic

Just like the last couple weeks in June, July is off to a quiet start. While there are a few tropical waves in the Atlantic, none look too impressive on satellite nor are any expected to develop.

Atlantic Wide 2D Enhanced Satellite

Typically, for the first third of July, tropical development occurs in the eastern Gulf or western Atlantic, sometimes along washed out frontal boundaries. Other areas of formation include the eastern Caribbean into the central Atlantic. Nonetheless, this time frame is not historically conducive to a lot of tropical geneses – there have only been 34 named storms that have formed between July 1 and 10th, dating back to 1851. And in fact, the entire month of July only accounts for about 8% of all tropical named storms in the Atlantic.

MyFoxHurricane Google Earth

While the eastern Caribbean/central Atlantic may be historically an area to watch for tropical development this time of the year, it looks less favorable so far this year. One of the primary reasons is the below average temperature anomalies for the waters in that area. Sea surface temperatures are running up to 2° below average in this part of the world. On the flip side, SST’s are running up to 2° above average in the Gulf of Mexico and western Atlantic near the Gulf Stream. Therefore, this would be the most likely spot for any tropical formation over the coming days/weeks.

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In addition to the cooler sea surface temperatures in the Caribbean, upper level winds remain extremely hostile to tropical development. Wind shear looks to remain unfavorable through at least the next week across the entire basin. Also, a surplus of dry Saharan air continues to advect into the Caribbean.

wrf_atl_shear_18

The biggest reason for the aforementioned hostile conditions pertains to the ongoing, and strengthening El Niño. As the waters warm across the Central and Eastern Pacific, this causes favorable conditions for strengthening tropical cyclones. A look at the sea surface temperature anomalies across the entire basin show some areas up to 3°+ above average for this time of the year. This is a good indicator of an ongoing El Niño, and one that is strengthening as well. In fact, the Climate Prediction Center is forecasting a moderate to strong El Niño to linger through the summer (and likely into the fall and winter as well) which will help to keep these conditions going. Therefore, it comes as no surprise that the Northwest and East Pacific hurricane seasons are off to near-record and record starts (respectively).

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The El Niño is also likely the culprit for a rare phenomenon in the Central Pacific – twin hemisphere cyclones. Tropical Cyclones Chan-hom and Raquel are at the same longitude but on opposite sides of the equator, something extremely rare for July considering it’s the winter months in the southern hemisphere. In fact, there have been only 3 tropical cyclones in the Pacific east of Australia in the month of July (since 1970), none of which have been as far north at Raquel.

Floater IR Enhanced 3

First Month of 2015 Atlantic Hurricane Season Ends; Nice and Quiet in the Atlantic

Tuesday is the last day of the first month of the 2015 Atlantic hurricane season. Between hostile upper level winds and dry Saharan air there are no major areas of interest. An upper level disturbance stirs up showers and storms near the Bahamas and moves east-northeast in the coming days. A complex of heavy thunderstorms flares up east of Mexico in the western Gulf. Moderate northwesterly shear overhead should keep this area disorganized. Elsewhere a tropical wave in the southern Caribbean battles high 50-60 kt shear limiting convection. Another tropical wave near the Lesser Antilles stands no chance as well with high wind shear in the vicinity. Officially no tropical cyclone development is expected over the next 5 days per the NHC.

Floater IR Enhanced

Wind shear values have been incredibly high in the south and western Caribbean. They remain just as high on Tuesday. A belt of 50-70 kt westerly shear remains in place from central America through the eastern Caribbean.  Tropical waves don’t stand a chance in this hostile environment.

GFS Wind Shear

Looking ahead to the weekend upper level winds remain unfavorable for tropical cyclone development. Moderate shear lingers near Central America and in the western Gulf and moderate to high wind shear stays in the place in the Caribbean.

GFS Wind Shear.png 2

As we enter the month of July Wednesday our attention to “hot spots” for tropical depression/storm development shifts a bit. Tropical cyclones can develop in the eastern Caribbean and enter the central Gulf or western Atlantic as they ride the perimeter of the Bermuda high in the Atlantic. The Bermuda high has been exceptionally strong and is another reason why the second half of June has seen no areas of tropical interest. Only 8% of named storms form during July too so expect a slow start to the second month of the Atlantic season.

Climatology July

 

 

 

No Sign of Life in the Atlantic

It’s not uncommon for tropical cyclone activity to be limited in late June and even early July but the Atlantic Basin is exceptionally quiet Monday. Deep convection in the northern Gulf and western Atlantic is associated with a  trough/stalled front. Elsewhere even cloud cover is lack there of. The central Atlantic is bone dry with widespread dry, dusty Saharan air firmly in place. This dry air and especially very high westerly wind shear keep the southern and western Caribbean stable. No tropical depression/storm development is expected for the next five days and beyond.

Atlantic Wide 2D Enhanced Satellite

Wind shear data from the University of Wisconsin shows the extent of hostile upper level winds in the Caribbean. A huge batch of high 50-70 kt westerly shear extends from Central America towards the Lesser Antilles. While these values may subside some (only a little) over the next 7 days moderate to high shear is forecast to linger in the Caribbean according to the GFS and European model.

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Even long-range models keep the entire Atlantic Basin tranquil with a very strong Bermuda high in control. Below is the 06Z GFS on Wednesday July 15th (more than 2 weeks from now). There are no signs of tropical cyclone organization, which of course is a good thing. Only 8% of named storms form during July. With a strengthening El Niño aiding in hostile upper level winds, extended periods of dry air and below average water temperatures in the south central Atlantic activity will hopefully stay limited.

gfs_atl_winds_93

While the central Atlantic is not a hot spot for development in June or July tropical waves do move through this region before making their way into the Caribbean or western Atlantic. Much of the south central Atlantic has water temperatures running 0.5-2.5°C below average. This could limit the number of hurricanes and especially strong hurricanes as we approach the peak of the 2015 season/Cape Verde season.

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Quiet Last Weekend of June in the Atlantic

The first month of the 2015 Atlantic hurricane season winds down on a quiet note. Bill dissipated well inland two weeks ago and since then there have been no areas of interest. The Atlantic season is typically off to a slow start. The first named storm forms on July 9th. In 2015 we’ve already seen two named storms (Ana & Bill) before the end of June. Meanwhile the east Pacific is off to a record active start due to El Niño. There are already three named storms and two hurricanes (both reached major hurricane strength). Upper level winds have been somewhat hostile lately so there is a lull in tropical cyclone development in the east Pacific. Despite the lull the 2015 east Pacific season is well ahead of schedule. The second hurricane doesn’t typically form until July 14th.

Early Season Named Storms

The Saharan Air Layer blasts the entire Atlantic basin with dry, dusty stable air. It’s responsible for an abnormally dry June in southeast Florida and in the Caribbean in places like Puerto Rico. Water vapor imagery shows dry air in the mid levels of the atmosphere in the south and west Caribbean and over the open Atlantic Saturday. A belt of high 50-60 kt westerly shear keeps convection to a minimum too in the southern Caribbean.

Gulf of Mexico WV

The graphic below courtesy the University of Wisconsin of Madison really shows the extent of the Saharan Air Layer (SAL) in the Atlantic (indicated by the yellow, orange and especially bright red). This dry air along with hostile upper level winds it the Caribbean swallow weak tropical waves. That’s the case Saturday with a tropical wave near the Lesser Antilles and another tropical wave over the open south central Atlantic.

splitEW

Long-range models keep the Bermuda high strong and firmly in place. The OZ Euro keeps convection to a minimum in the Gulf and Caribbean into next Sunday morning. Officially per the NHC no tropical cyclone development is expected for the next five days.

ECMWF MSLP and Precip Rate

 

Exceptionally Dry in the Caribbean; Long Quiet Stretch in the Atlantic Basin

With less than a week left in the first month of the 2015 Atlantic hurricane season it is likely to wrap up with no more named storms. Ana formed in late May and Bill dissipated last weekend. Since then the Atlantic Basin is exceptionally quiet. This is not out of the norm as typically only 6% of named storms form in June. Strong upper level winds and dry Saharan air are the culprit. Scattered storms move into central America Wednesday associated a tropical wave but they are disorganized. A weak upper low nearby enhances 20-30 kt shear over the disturbance. Convection is lack there of with a tropical wave in the central Caribbean and south central Atlantic. Both of these features move westward and won’t develop.

Atlantic Wide 2D Enhanced Satellite

The Caribbean is especially hostile Wednesday. Wind shear values are in the moderate to high range as indicated by the GFS wind shear model.

GFS Wind Shear with Text

Even a week from now upper level winds are unfavorable for tropical cyclone development. In fact, upper level winds actually become even less favorable in the western Gulf and western Atlantic in the wake a stalled front. Moderate to high wind shear remains entrenched in the eastern Caribbean.

GFS Wind Shear with Text.png 2

While June is typically an inactive month in the Atlantic disturbances/tropical waves do bring beneficial rain to the Caribbean as they pass through. This June has been so dry for much of the region with limited tropical moisture. Parts of Puerto Rico are actually under a moderate to severe drought according the U.S. Drought Monitor. Models indicate El Niño will continue to strengthen later this summer and fall which raises extended drought concerns. El Niño is associated with strong wind shear and extended periods of dry air in the Atlantic and Caribbean.

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Quiet For a While in the Atlantic

As advertised Monday convection is limited in the entire Atlantic Basin. Between dry African air, hostile upper level winds and a strong Bermuda high no tropical cyclone development is expected for the next 5 days and beyond. A tropical wave near Hispaniola feels the influence of an upper low. This keeps convection sheared and disorganized. Drier air plays a role too. Elsewhere there are no areas of interest.

Atlantic Wide 2D Enhanced Satellite

El Niño plays a big role in the 2015 Atlantic hurricane season especially if it continues to strengthen into late summer/fall as models suggests. During El Niño strong wind shear and periods of dry air inhibit tropical cyclone development in the Atlantic (especially the number of strong major hurricanes). According to NOAA there is a greater than 90% chance that El Niño will continue through the Fall and around an 85% chance it will last through the 2015-2016 Winter. While water temperatures are in the low to mid 80s for much of the Gulf, Caribbean and tropical western Atlantic they are running a bit below average in a few spots. The Bay of Campeche is running .5-2°C below normal. A few pockets of the western Caribbean and especially the south central Atlantic (where some of the strongest storms of the season originate) are below normal too. Meanwhile equatorial Pacific water temperatures are on the rise and are a few degrees Celsius above average. There are already 3 named storms, 3 hurricanes and 2 major hurricanes in the east Pacific. Andres, Blanca and Carlos thrived over very warm Pacific waters.

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In the Climate Prediction Center’s weekly update NOAA reports that sea-surface temperature anomalies increased since the Spring in the equatorial Pacific Ocean. Computer models are still predicting that sea-surface temperature anomalies will continue to increase through the Fall. If this holds true the 2015-2016 could be wetter than normal for the southern U.S. with an increased threat of severe weather. The graphic below is courtesy of the Climate Prediction Center’s weekly update issued on Monday June 22nd.

 

El Nino

Tranquil in the Atlantic This Week

After an active week last week with Tropical Storm Bill the third week of the 2015 Atlantic season starts on a quiet note. There may be no signs of life in the Atlantic Basin for a while too, which of course is a good thing. While 2015 is off to an active start with 2 named storms before the end of June typically only 6% of named storms form this month. Only 34 named storms have formed in the Gulf, Caribbean or Atlantic from June 21-30 since 1851.

MyFoxHurricane Google Earth

There are only a few tropical waves in the Atlantic Basin. The most vigorous of the 3 brings disorganized convection to the Lesser Antilles Monday. Showers and storms remain disorganized with an upper low nearby keeping upper level winds hostile.

Atlantic Wide 2D Enhanced Satellite

While strong high pressure keeps convection limited in the Gulf and western Atlantic lots of dry dusty African air keeps the Caribbean and Atlantic stable too. The Saharan Air Layer is quite active and covers almost all of the central Atlantic (not a hot spot for development in June). This settles into the western Caribbean and Gulf too.

Omni

The reliable European and GFS model keep the tropics quiet for at least another 5-7 days. Notice the strong Bermuda high parked over the Atlantic through next Monday afternoon via the GFS and no areas of low pressure spinning up in the Gulf or Caribbean. Pressure does however stay low in the eastern Pacific.

GFS MSL and Precip Rate

Bill Hangs On; Wet Weekend From Ohio Valley to Mid Atlantic

It’s truly incredible how impressive Tropical Depression Bill is well inland 4 days after landfall.  The flooding threat continues this weekend. The image below is courtesy NASA and was taken Saturday morning. Bill maintains a well-defined circulation as it moves through an already saturated Ohio Valley Saturday. It gradually lose tropical characteristics Saturday but the remnants may recharge in the Mid Atlantic Sunday where heavy rain is anticipated.

Nasa

Tropical Depression Bill may bring an addition 2-3″ of rainfall to the Ohio Valley over the next 24 hours. As of 8 AM EDT 8.26″ was recorded in Fults, Illinois, 8.80″ in Plainville, Indiana,, 5″ in Georgetown, Kentucky, and 5.74″ in Fort Loramie, Ohio.

Floater Satellite-Radar Weekend AM

The RPM model is in the line with Weather Prediction Center and suggests 1-3″ of rainfall in the Mid Atlantic by Monday afternoon including Washington, DC, Baltimore, and Philadelphia. Isolated area may pick up higher amounts.

Floater GFS Precip. Acc. With Plot

The Atlantic Basin will stay quiet for at least the next 5-7 days with a strong ridge of high pressure firmly in place.  Dry dusty Saharan air keeps the Caribbean and Atlantic stable too.

Caribbean WV

 

 

Tropical Depression Bill Drenches the Ozarks 3 Days After Landfall; Enter Quiet Stretch in Atlantic

More than 3 day after landfall in southeast Texas Tropical Depression Bill maintains its structure and tropical characteristics. It is still dumping heavy rainfall in the Ozarks. More than five and half inches of rain is recorded in Springfield Missouri and almost 5 inches of rain fell in Sullivan, Illinois. While the National Hurricane Center is no longer issuing advisories the Weather Prediction Center is due to a continued a heavy rain threat. This shifts to the Ohio Valley Saturday and to the Mid Atlantic and Northeast Sunday and Monday in conjunction with a frontal boundary.

Fly to Gulf Disturbance

Bill

The Weather Prediction Center estimates 2-4″ of rain is possible by Monday morning (isolated areas will pick up higher amounts) from southeast Missouri to West Virginia. Moisture content won’t be quite as impressive as the remnants of Bill make it to the mid Atlantic and northeast late in the weekend but some downpours will be locally heavy.

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The good news is we enter a quiet stretch in the Atlantic Basin for at least the next 5 days. A strong ridge of high pressure in the Atlantic squashing the chances of tropical cyclone development (too much dry sinking air). The Caribbean and Gulf look to stay quiet too and none of the reliable computer models development anything of interest for the next 5-7 days.

ECMWF MSLP and Precip Rate

Tropical Depression Bill Continues to Cause Issues Inland

Tropical Depression Bill continues to track inland into eastern Oklahoma. The storm has actually held onto its tropical characteristics and has a well-defined circulation center with it (as is evident by the radar composite below).

TD Bill Radar

Bill and the thunderstorms along with it have produced extremely heavy rainfall across portions of Texas, Oklahoma, Louisiana, and Arkansas. Some rainfall totals have even exceeded a foot!

City Rainfall

The good news with TD Bill is that there is less in the way of impressive thunderstorm activity associated with the storm by Thursday evening. In fact, the enhanced satellite imagery doesn’t show much convective activity at all.

TD Bill Enhanced Satellite

Although TD Bill is weaker and likely to become post-tropical by early Friday morning, it is still a dangerous storm, and will continue to be so on its track to the east. Its initial motion is to the ENE at 7mph, but it will start to pick up some speed by Friday and by Sunday, it should be near the Mid-Atlantic coastline.

Bill Track

As Bill and its remnants work to the east in the coming days, it will continue to drop copious amounts of rainfall. The model below depicts a wide swath of 1″-3″ from eastern Missouri through the Ohio River Valley and into the Mid-Atlantic. There will likely be some locally higher amounts possible.

Floater GFS Precip. Acc. With Plot

Once Bill clears into the Atlantic, there isn’t much on the horizon. The GFS model keeps high pressure in control in the Atlantic right through next week, with sinking motion preventing any tropical genesis.

GFS Global