2015 indicators: Instability / SST's / MSLP / Steering / Sal

[gatorcane]

Another impressive ridge the global models are showing building across the Atlantic by day 10. 12Z GFS 500MB pattern below:

[ronjon]

Umm...there's another one much more recent. Hurricane Andrew in 1992 during a moderate-to-strong El Nino that year.

That El Niño ended May 1992 August was actually cool neutral not even close to El Niño threshold. May 1991 till Q1 1992 was under a weak Niño which exploded to a strong event by December 1991

Actually no - according to the CPC, it was still +0.5 C for JJA period and had been above +1.5 C during the spring of 1992. So I agree, it was waning, but still an El Nino year.

[Yellow Evan]

Umm...there's another one much more recent. Hurricane Andrew in 1992 during a moderate-to-strong El Nino that year.

That El Niño ended May 1992 August was actually cool neutral not even close to El Niño threshold. May 1991 till Q1 1992 was under a weak Niño which exploded to a strong event by December 1991

Actually no - according to the CPC, it was still +0.5 C for JJA period and had been above +1.5 C during the spring of 1992. So I agree, it was waning, but still an El Nino year.

If you look at the weeklies, they were cold neutral by the time Andrew rolled around.

If it had waned by early summer, how does 1992 qualify as an El Nino year?

[Ntxw]

The logic wouldn't make sense for transition years if we go by that. For example spring of 2010 was a waning El Nino as was 1998, but quickly became strong Ninas later in the year. Do we define them as El Nino years? No they are La Nina years. But ENSO is defined by 5 consecutive trimonthlies, once you lose the reading it is no more. There are some cases you can argue it dips slightly below but then return to the enso state as still that event. However the remainder of 1992 did not thus the 1992-1993 season was not El Nino.

[TheStormExpert]

Another impressive ridge the global models are showing building across the Atlantic by day 10. 12Z GFS 500MB pattern below:

http://i.imgur.com/2cACXbz.gif

Still looks like there is enough opening or weakness though to allow something to recurve just east of Florida thanks to that Great Lakes trough if a storm were to form under a steering pattern like this. Of the the NC Outer Banks could get grazed on the way out.

What are your thoughts?

[MiamiensisWx]

Another impressive ridge the global models are showing building across the Atlantic by day 10. 12Z GFS 500MB pattern below:

http://i.imgur.com/2cACXbz.gif

Still looks like there is enough opening or weakness though to allow something to recurve just east of Florida thanks to that Great Lakes trough if a storm were to form under a steering pattern like this. Of the the NC Outer Banks could get grazed on the way out.

What are your thoughts?

A long-range model run more than two months before the peak of the season really shouldn't be used as a guideline as to how the pattern may set up when a cyclone is actually in the Atlantic.

As an aside, I decided to take the consensus among people here and make a hypothetical 2015 timeline and season. (Disclaimer: I actually don't expect any hurricanes to hit the U.S. or the Caribbean states in 2015.)


(Background map is courtesy of Unisys.)

CLAUDETTE (07–10 July): TS Claudette forms from a mid-level trough just off the southeast coast of FL and is wedged between a weak shortwave over the Midwest and a rebuilding Bermuda High off the Southeastern U.S. It moves north-northwest, reaching TS status as it parallels the east coast of FL. It peaks just east of Daytona Beach and later makes landfall over Ponte Vedra Beach, FL, at its peak. It then moves northward over southeast GA while maintaining TS status due to its proximity to the Atlantic. After curving north-northeast, the TC dissipates near the SC/NC border.

Peak winds: 45 kt (50 mph). | Landfall location: 30.2°N 81.4°W. | Landfall winds: 45 kt (50 mph).

DANNY (12–22 August): H Danny forms from a tropical wave and an upper low (TUTT) just east of the Leeward Islands and moves west-northwest. It reaches TS status northwest of Anegada. The system struggles to intensify further under moderate to strong vertical shear, but this relaxes as Danny passes south of Providenciales, Turks and Caicos Islands. The cyclone subsequently becomes a hurricane south of Crooked Island, Bahamas, and then undergoes more rapid deepening as it nears Andros Island. After crossing the island, Danny becomes a major hurricane over the Gulf Stream before landfall in South Florida. It enters the Gulf of Mexico near Cayo Costa State Park as it bends northwest toward Apalachee Bay. Danny eventually turns north and strikes the mouth of the Aucilla River before heading north-northeast over GA and the western Carolinas. It dissipates near the PA/NY border.

Peak winds: 125 kt (145 mph). | First landfall location: 25.6°N 80.3°W. | First landfall winds: 125 kt (145 mph). | Second landfall location: 30.1°N 84.0°W. | Second landfall winds: 75 kt (85 mph).

ERIKA (10–22 September). H Erika develops from a tropical wave off West Africa during peak season. Moving west-northwest, the system becomes a tropical storm but struggles with low instability and moderate to strong vertical shear, so it fails to intensify significantly for several days. It eventually turns northwest and reaches hurricane status at higher latitudes. Erika then curves north and northeast before transitioning into an extratropical cyclone with hurricane-force winds.

Peak winds: 80 kt (90 mph). | Landfall location: None.

FRANKLIN (28 September–04 October): H Franklin formed from a tropical wave and a mid-level trough in the central Atlantic. It quickly attained tropical storm status as it moved north and then north-northeast. Curving northeast, it later attained hurricane status, only to weaken, head east, and become extratropical with gale-force winds.

Peak winds: 65 kt (75 mph). | Landfall location: None.

GRACE (28 October–13 November): A tropical wave spawns a depression that moves slowly west through the northeast Caribbean before abruptly turning northeast and accelerating. The system then slows and turns north-northwest before strengthening into TS Grace. It later transitions into a subtropical cyclone before becoming extratropical and heading northeast for several days across the North Atlantic.

Peak winds: 55 kt (65 mph). | Landfall location: None.

[gatorcane]

That is pretty cool how you created that hypothetical map MiamiensisWx! Well we could easily get some tracks like that. We should find out soon enough!

[Hurricaneman]

Most people forget that 1992 was a Neutral year but it seems that the effects of the previous El Nino were still present and was the cause of Andrew not doing much until it got above 20N north of the shear zone

The posts in this forum are NOT official forecast and should not be used as such. They are just the opinion of the poster and may or may not be backed by sound meteorological data. They are NOT endorsed by any professional institution or storm2k.org. For official information, please refer to the NHC and NWS products

[Andrew92]

The F name is Fred this year, not Franklin.

-Andrew92

[Yellow Evan]

Most people forget that 1992 was a Neutral year but it seems that the effects of the previous El Nino were still present and was the cause of Andrew not doing much until it got above 20N north of the shear zone

The posts in this forum are NOT official forecast and should not be used as such. They are just the opinion of the poster and may or may not be backed by sound meteorological data. They are NOT endorsed by any professional institution or storm2k.org. For official information, please refer to the NHC and NWS products

That is true, however, 1992 is still technically not an El Nino year.

[crownweather]

Do you have a link for the cyclone genesis potential model for July? Am curious to take a look at it for myself.

Thanks,

It was only 2 weeks before TS Bill spawned on the global models thread the deep tropics was being written off for the month of June. Cyclone genesis potential model's for the full month of July hint @ a above average month of 1-2 systems in the Atl.


The posts in this forum are NOT official forecast and should not be used as such. They are just the opinion of the poster and may or may not be backed by sound meteorological data. They are NOT endorsed by any professional institution or storm2k.org. For official information, please refer to the NHC and NWS products.

[MiamiensisWx]

As an aside, I just finished some interesting research based on an old theory: that the track and location of the first named storm could offer clues as to how the rest of the storms will track. I looked at all the seasons that I could find in which a) the first named storm hit the U.S. in May or June and 2) was moving between west and north-northwest at landfall. This season, the first named storm, TS Ana, hit the U.S. in May while moving north-northwest.

After research, I found some very startling data that may support what some people have been saying about this season. Overall, the results indicate a strong signal for a FL hurricane threat, with a significant major hurricane threat to the state as well.

The results indicate that such a storm hit in 19 seasons: 1851, 1854, 1871*, 1873*, 1874, 1880*, 1888*, 1899, 1913, 1916, 1921, 1929, 1931, 1939, 1960, 1964*, 1972, 1978, 1993, and 2005*. According to these results, ≈70% of these years had at least one hurricane landfall in FL. Of the years with at least one hurricane strike in FL, ≈57% had at least one major landfall in FL and ≈43%* had two or more hurricanes hitting FL.

Notable storms: major landfalls in 1851 (Cat. 3, NW FL), 1871 (Cat. 3, east-central FL), 1873 (Cat. 3, SW FL), 1888 (Cat. 3, SE FL), 1921 (Cat. 3, Tampa Bay), 1929 (Cat. 3, SE FL), 1960 (Cat. 4 Donna, SE/SW FL), 2005 (Cat. 3 Wilma, SW FL).

Other data: of the years with at least one hurricane hit in FL, ≈57% had at least one hurricane strike on the east coast of the state. 1871 had two hurricanes hitting east-central FL, including one major, plus a Cat. 1 near Cedar Key. 1880 had a Cat. 2 near Melbourne and a Cat. 1 north of Tampa Bay. 1888 had a major hurricane near Miami and a Cat. 2 near Cedar Key. 1929 had a major hurricane near Tavernier in the FL Keys. 1939 had a Cat. 1 near Stuart. 1960 had Donna in the Keys and the SW mainland of FL. 1964 had Cat. 2 Cleo hitting North Miami, Cat. 2 Dora hitting St. Augustine, and Cat. 2 Isbell near Everglades City. 2005 had Cat. 1 Katrina near North Miami and major hurricane Wilma near Cape Romano.

Underline indicates at least one hurricane landfall in FL. Bold indicates at least one major hurricane landfall in FL. * (asterisk) indicates ≥ 2 hurricane hits in FL. Red indicates strong El Niño seasons.

[WPBWeather]

Your work is very thoughtful and reasoned but NOT what I wanted to hear

As an aside, I just finished some interesting research based on an old theory: that the track and location of the first named storm could offer clues as to how the rest of the storms will track. I looked at all the seasons that I could find in which a) the first named storm hit the U.S. in May or June and 2) was moving between west and north-northwest at landfall. This season, the first named storm, TS Ana, hit the U.S. in May while moving north-northwest.

After research, I found some very startling data that may support what some people have been saying about this season. Overall, the results indicate a strong signal for a FL hurricane threat, with a significant major hurricane threat to the state as well.

The results indicate that such a storm hit in 19 seasons: 1851, 1854, 1871*, 1873*, 1874, 1880*, 1888*, 1899, 1913, 1916, 1921, 1929, 1931, 1939, 1960, 1964*, 1972, 1978, 1993, and 2005*. According to these results, ≈70% of these years had at least one hurricane landfall in FL. Of the years with at least one hurricane strike in FL, ≈57% had at least one major landfall in FL and ≈43%* had two or more hurricanes hitting FL.

Notable storms: major landfalls in 1851 (Cat. 3, NW FL), 1871 (Cat. 3, east-central FL), 1888 (Cat. 3, SE FL), 1921 (Cat. 3, Tampa Bay), 1929 (Cat. 3, SE FL), 1960 (Cat. 4 Donna, SE/SW FL), 2005 (Cat. 3 Wilma, SW FL).

Other data: of the years with at least one hurricane hit in FL, ≈57% had at least one hurricane strike on the east coast of the state. 1871 had two hurricanes hitting east-central FL, including one major, plus a Cat. 1 near Cedar Key. 1880 had a Cat. 2 near Melbourne and a Cat. 1 north of Tampa Bay. 1888 had a major hurricane near Miami and a Cat. 2 near Cedar Key. 1929 had a major hurricane near Tavernier in the FL Keys. 1939 had a Cat. 1 near Stuart. 1960 had Donna in the Keys and the SW mainland of FL. 1964 had Cat. 2 Cleo hitting North Miami, Cat. 2 Dora hitting St. Augustine, and Cat. 2 Isbell near Everglades City. 2005 had Cat. 1 Katrina near North Miami and major hurricane Wilma near Cape Romano.

Underline indicates at least one hurricane landfall in FL. Bold indicates at least one major hurricane landfall in FL. * (asterisk) indicates ≥ 2 hurricane hits in FL. Red indicates strong El Niño seasons.

[MiamiensisWx]

As an aside, I just finished some interesting research based on an old theory: that the track and location of the first named storm could offer clues as to how the rest of the storms will track. I looked at all the seasons that I could find in which a) the first named storm hit the U.S. in May or June and 2) was moving between west and north-northwest at landfall. This season, the first named storm, TS Ana, hit the U.S. in May while moving north-northwest.

After research, I found some very startling data that may support what some people have been saying about this season. Overall, the results indicate a strong signal for a FL hurricane threat, with a significant major hurricane threat to the state as well.

The results indicate that such a storm hit in 19 seasons: 1851, 1854, 1871*, 1873*, 1874, 1880*, 1888*, 1899, 1913, 1916, 1921, 1929, 1931, 1939, 1960, 1964*, 1972, 1978, 1993, and 2005*. According to these results, ≈70% of these years had at least one hurricane landfall in FL. Of the years with at least one hurricane strike in FL, ≈57% had at least one major landfall in FL and ≈43%* had two or more hurricanes hitting FL.

Notable storms: major landfalls in 1851 (Cat. 3, NW FL), 1871 (Cat. 3, east-central FL), 1873 (Cat. 3, SW FL), 1888 (Cat. 3, SE FL), 1921 (Cat. 3, Tampa Bay), 1929 (Cat. 3, SE FL), 1960 (Cat. 4 Donna, SE/SW FL), 2005 (Cat. 3 Wilma, SW FL).

Other data: of the years with at least one hurricane hit in FL, ≈57% had at least one hurricane strike on the east coast of the state. 1871 had two hurricanes hitting east-central FL, including one major, plus a Cat. 1 near Cedar Key. 1880 had a Cat. 2 near Melbourne and a Cat. 1 north of Tampa Bay. 1888 had a major hurricane near Miami and a Cat. 2 near Cedar Key. 1929 had a major hurricane near Tavernier in the FL Keys. 1939 had a Cat. 1 near Stuart. 1960 had Donna in the Keys and the SW mainland of FL. 1964 had Cat. 2 Cleo hitting North Miami, Cat. 2 Dora hitting St. Augustine, and Cat. 2 Isbell near Everglades City. 2005 had Cat. 1 Katrina near North Miami and major hurricane Wilma near Cape Romano.

Underline indicates at least one hurricane landfall in FL. Bold indicates at least one major hurricane landfall in FL. * (asterisk) indicates ≥ 2 hurricane hits in FL. Red indicates strong El Niño seasons.

Some additional support for this assessment can be found in data gleaned from ESRL. I did a correlation between the May-June Atlantic SSTA gradient (Tropical North Atlantic Index, or TNA) and the August-September 700-mb height pattern. The TNA data indicate that the May value, as well as the April value, was negative, indicating below-average SSTA in the eastern tropical Atlantic and above-average SSTA in the northwest Atlantic. (A positive TNA would indicate above-average SSTA in the eastern tropical Atlantic and below-average SSTA in the northwest Atlantic.) Note the cool SSTA around Greenland as well. Based on the charts below, I found that there was a positive correlation for the eastern tropical Atlantic and a negative correlation for the northwest Atlantic. Positive implies a linear relationship between values--i.e., positive/negative SSTA translate into positive/negative 700-mb heights--while negative implies an inverse relationship--i.e., positive/negative SSTA translate into negative/positive 700-mb heights.

With these relationships in mind, I found that the expected August-September steering pattern matches that which several of the analogs might suggest. Keep in mind that factors to be considered include not only the SSTA gradient, but also the orientation of the gradient: is it north to south, east to west, etc.? In this case, note that the positive SSTA anomalies in the east-central Atlantic are stretched east to west, as are the negative SSTA anomalies in the eastern tropical Atlantic to the south. The positive SSTA anomalies in the northwest Atlantic are stretched north to south, while the negative anomalies near Greenland are oriented east to west. These orientations can influence the wavelengths down the road and affect how not only where the mean ridges and troughs set up, but also their amplitude and orientation.

So far, this year, the Bermuda High has been elongated east to west, which actually matches the correlation between the SSTA and the 700-mb set-up during peak season as well. Note the strong correlation between the charts and the sharply positive NAO (elongated trough over Greenland) we have seen thus far this year. The charts also suggest a split flow over the western Atlantic and North America, with the northern jet stream divided into two branches: a southerly angled W-E over the U.S./Canadian border and a northerly angled NW to SE over northern Canada. The interaction between these jets and between the Hudson Bay/Bermuda Highs could influence possible development off the SE coast and affect the movement of the mean trough there. Note that, with the drought over the Plains gone, the mean U.S. ridge has retrograded over to the West Coast (severe drought there), which could allow the SE weakness to migrate west at times.

In fact, there is a decent correlation between the March-April NAO (this year's was solidly positive) and the August-September 700-mb height. In line with the other data, the NAO correlation would place a mean weakness over the SE U.S. during peak season:



Using the other correlation data (between SSTA and 700-mb heights), I decided to draw the expected 700-mb heights--and their associated steering patterns--in August-September on top of the May-June SSTA. The second chart shows the 700-mb correlation.




Overall, the data match up well with both my hypothetical 2015 season (based on other members' consensus) and the landfall data that I gathered. Still, I'll bet that FL escapes, somehow, as it has done the past several seasons, no matter what the data say.

[ninel conde]

With conditions getting more hostile as each day goes, the question isnt tracks, but will anything of interest form.

[tolakram]

June is June, I'm waiting for August/September to see if there's a window of good conditions or if we have an unprecedented el nino that completely suppresses the season. We've seen decent conditions in the gulf and near Florida already, all that's been missing is a trigger. Hurricane season is all about odds ... is something in the right place at the right time to form. We have a major hurricane nearly every year, the question is where will it be and where will it go.

[Ntxw]

Wow! I just took a look at the surface and upper-level conditions across the Caribbean over the next week and I can't recall seeing such a hostile environment. Big SAL is racing across the Caribbean. Surface winds in the central to SW Caribbean predicted to be in the 30-40 kt range this weekend. Winds at 850mb nearing 55 kts in the SW Caribbean. Wind shear as high as 90 kts!

Looks like verification near or maybe over 100kts! I don't think I've ever seen such high shear values this low latitude in the summer, is this some kind of record for this period? I know 1997 was consistently 60-70knts but I can't find charts for it. Doesn't matter what side of the fence you are on, its an amazing weather anomaly phenomenon on its own.

[wxman57]

I don't believe there's any correlation between the direction of the first storm at landfall and future tracks. Ana was moving NW, not NNW at landfall. I measure 326.1 deg, which is still NW as NNW starts at 326.26 deg. What are the statistics for first storm movement at landfall? What years are included, what is the distribution of directions?

As for correlations, there's a good correlation between moderate to strong El Ninos and a lack of East U.S. Coast impacts. There's no such correlation for Northern Gulf Coast impacts, or lack of impacts, in an El Nino season. With the trof along the East U.S. Coast, the storms that form north of the Caribbean will probably recurve east of the U.S. Of course, it's all a matter of timing.

Watch those SST anomaly graphics - a high warm anomaly doesn't necessarily mean high heat contact is also high there. Check out the Gulf of Alaska and the bright reds there. I wouldn't expect a hurricane to form there because SSTs are much higher than normal.

[ninel conde]

Wow! I just took a look at the surface and upper-level conditions across the Caribbean over the next week and I can't recall seeing such a hostile environment. Big SAL is racing across the Caribbean. Surface winds in the central to SW Caribbean predicted to be in the 30-40 kt range this weekend. Winds at 850mb nearing 55 kts in the SW Caribbean. Wind shear as high as 90 kts!

Looks like verification near or maybe over 100kts! I don't think I've ever seen such high shear values this low latitude in the summer, is this some kind of record for this period? I know 1997 was consistently 60-70knts but I can't find charts for it. Doesn't matter what side of the fence you are on, its an amazing weather anomaly phenomenon on its own.

This picture is worth 1000 words

http://moe.met.fsu.edu/cgi-bin/gfstc2.c ... hour=180hr

3 indicators of a dead tropics
A-atlantic high too strong and too far south due to the negative NAO
B-The strong high to the north and that low over nw south america are creating ripping low level easterlies
C-Again that strong high to the north and low over west africa is ripping down montrous amounts of bone dry air into the tropics.

I fully expect things to go downhill from here with the most unfavorable conditions from mid-aug to mid oct.

[CrazyC83]

I think any storms will have to form either in the Gulf of Mexico (and stay there, like Bill), or in the subtropical Atlantic near/north of 30N (like Ana). I think the deep tropics are as good as dead this year.