PRELIMINARY SEASONAL HURRICANE OUTLOOK FOR THE 2015 HURRICANE SEASON…ISSUED APR. 16, 2015…8:40 P.M. EDT

ALL forecasts contained on this site,  are based on my analysis and knowledge of various forecast tools, including information contained in NHC products, and are not copies from any other entity.

Graphics are linked.

Greetings to everyone!

I have taken time away from severe weather, in order to put together this preliminary Seasonal Hurricane Outlook.  Based on analysis of various forecast parameters, looks as if this upcoming season may pretty well resemble that of last season, in that I currently expect a below average season, albeit with maybe a caveat or two.

Based on my analysis of the most recent forecast update regarding the onset of an El Nino episode, I have come up with 5 analog years in reference to the ONI (Oceanic Nino Index) that closely resemble the “forecast trend” vice actual ONI Value, albeit a couple of the analog year values are close.  These analog years are 1957, 1972, 1982, 1991, and 1997.  While I do believe we will experience El Nino this season, I am backing away from a strong El Nino, even though the majority of climate modeling indicates different. If you remember, these models and trends pretty much had the same prediction for the past 2 years, calling for a fairly strong El Nino episode.  I believe this should be a moderate to a strong episode, but not as strong let’s say as 1997-98 or 18982-83 episodes.  The current 30 day running mean of the Southern Oscillation Index (SOI) remains sharply negative, indicating trade winds blowing from west to east from Australia toward the east.  It is noted a sudden ramp up toward positive has occurred, but is unknown whether this is just a sudden spike, or a trend.

The following is the ONI value index:
http://www.cpc.noaa.gov/products/analysis_monitoring/ensostuff/ensoyears.shtml

EL NINO OF 1982 -83 /1997-1998
dec82_sep97_ssta
CURRENT EL NINO FORECAST
poama.nino34.small

CURRENT SOI GRAPH
soi30

Based on the ONI analogs, we pretty much averaged a total of 8 Storms, 3 Hurricanes, and 1 Intense Hurricane.   Based on data from 1968 – 2003  and 1981 – 2010 an average season has been said to have 11 – 12 Storms, 6 hurricanes, and 2 -3 Intense Hurricanes.  The long term average of 100 years however was established at 10-6-2.  After doing some averaging and dividing, I have come up with the following totals for the 2015 Hurricane Season.

TOTAL STORMS:             8 – 10
HURRICANES:                   3 – 5
INTENSE HURRICANES: 1 – 2

This is a preliminary estimate, and I will try to have an update prior to the onset of the season.  I have based my higher estimates on the premise that SST Anomalies in the GOMEX and along the U.S. east coast may remain close or at the current values.  As we have seen in past patterns fitting this current one, some storms forming above 20N have become Major Hurricanes once encountering these warmer anomalies, provided wind shear and dry air do not cause a hindrance.

IRT (In Reference To) the current SST Anomalies, one can see the majority of the warmth along the Equatorial Pacific remains fairly far to the west.  In addition, you’ll notice the warmest anomalies in the Atlantic focused in the GOMEX and North Central Atlantic, while anomalies in the MDR remain below average.  The below average anomalies in the MDR are similar to what we saw develop during the AUG – OCT. time frame, which helped limit activity.  This has been caused mainly by the NAO remaining in almost a constant positive state since the end of last hurricane season, implying the subtropical ridge has been stronger than normal so far this year.  This has allowed for greater evaporational cooling in the MDR, along with the upwelling of cooler water along the African coast.  Another factor in the cooler anomalies along the African coast can be attributed to the SAL. So, with the current setup, we pretty much have a reversal in the Atlantic Ocean Tripole.  The current setup (should it remain) would indicate convergence and “net lift” are and should be focused in the GOMEX, and eastward in the warmer anomalies.  This would indicate a higher probability of close in development this season.  One concern I have with this setup is, it entertains a better probability for U.S. strikes, so I’ll be paying particular attention to stalled frontal boundaries and any possible “situational” developments.  The current SST Anomaly setup shows much cooler anomalies in the far northern Atlantic, the warmer anomalies as mentioned, and cooler anomalies in the MDR.  A more “normal” setup, in where we would see an increase in activity in the MDR, is a tripole setup as seen in the third SST Anomaly map.  This setup promotes the most net lift and upward motion (rising warm air) focused over the MDR.

CURRENT SST ANOMALIES FROM NOAA / UNISYS

sst_anom

AVERAGE ATLANTIC OCEAN TRIPOLE
tripole

As you noticed, I mentioned the NAO (North Atlantic Oscillation) and the SAL (Saharan Air Layer).  Both of these features have contributed to the below average SST anomalies noted in the first SST Anomaly map, and the following graphics indicate the NAO Values since the beginning of this year, and the current SAL situation.  We may see a brief period of the far eastern Atlantic warming slightly, as the NAO is poised to turn negative during the next week, and forecast 1000 – 500 mb maps indicate the NAO may remain neutral to negative for the next couple weeks.

CURRENT NAO FORECAST
nao.sprd2

nao.mrf

SAL SATELLITE VIEW
truecol-1

The current TCHP (Tropical Cyclone Heat Potential) is pretty much the same as it was this time last year, however maybe slightly ahead around the Greater Antilles.  Values of this “potential” of >60, provided other factors are favorable, will support an Intense Hurricane.

TCHP APR. 15, 2014
2014105at

TCHP APR. 15, 2015
2015105at

So as an overall “look”, pretty much the negating factors right now, resemble last season…Cooler MDR, higher pressure over the Atlantic, SAL, dry air over the majority of the Atlantic, which could continue with the onset of El Nino, in addition to wind shear should El Nino strengthen and the NAO remain positive.

Another feature which could either help or hinder activity, is the MJO (Madden Julian Oscillation)  {BTW, most of these features are listed with links, in StormW’s Toolbox}.

The MJO is rather difficult to predict,  However, up until recently, the MJO signal has been very strong.  This index indicates where upward vertical velocities are experienced.  The further from the center the index is, the stronger the MJO pulse.  During the first couple of months in our hurricane season, we generally look for an increase in tropical activity when the MJO index is in “phases” or “octants” 8 and 1.  We usually see an uptick in activity in the GOMEX and Caribbean Sea during this time.  Again, this mainly applies to June and July.

MADDEN JULIAN OSCILLATION PHASE DIAGRAM
rmm.phase.Last40days

Have a blessed day!

T. F. “STORM” WALSH III
GMCS, USCG (ret)
METEOROLOGIST / HURRICANE SPECIALIST / SEVERE WEATHER SPECIALIST MEMBER WEST CENTRAL FLORIDA AMS
CoCoRAHS OBSERVER  

 

Advertisements

About palmharborforecastcenter

I am a Tropical Forecast meteorologist, providing hurricane forecasts during the Atlantic Hurricane Season. I retired from the U.S. Coast Guard in July of 2001. Meteorology became my passion in high school, and I have continued my educational background in meteorology since 1996, when I undertook the study of Tropical Meteorology. While working toward my degree, I had to unexpectedly withdraw from college due to my oldest sons medical reasons. I do however, meet the educational criteria of the AMS to be recognized as a meteorologist. Studies include, but are not limited to the Navy Aerographers Mate course, Naval METOC meteorology course, Meteorology 2010 Sophomore level course while attending St. Petersburg College, Clearwater, FL., Basic Forecasting course for operational meteorologists from Rapid WX, meteorology institute, a four month meteorological internship, and extensive research on numerous meteorological topics such as the MJO, NAO, satellite imagery interpretation, etc. I have been forecasting Tropical Weather (Tropical Storms and Hurricanes) since 1996, with my main client being three different Coast Guard Commands.
This entry was posted in Tropical Synopsis. Bookmark the permalink.

4 Responses to PRELIMINARY SEASONAL HURRICANE OUTLOOK FOR THE 2015 HURRICANE SEASON…ISSUED APR. 16, 2015…8:40 P.M. EDT

  1. dellamom says:

    Thank you, Storm. I was just able to do a quick read this morning, but is my impression that, although a lower incidence of storms is forecast, mainland US involvement is greater? (Gotta get my husband going on that whole house generator!)

    • Dellamom, I believe we could see a greater risk of landfalls early on. Given that June and July, we see development mainly in the Gulf and Caribbean as far as climatology, with the sst anomalies that warm, and that close in, closer development is likely. Anything that forms in the GOMEX would most likely threaten the Gulf coast, which has abetter prob. if those anomalies remain. East of there, my thinking right now would be OBX, slimmer possibility of Long Island, Cape Cod area, which will depend mostly on the ridge/trof setup at the time.

  2. originallt says:

    Thanks, Storm. At the “Old Site” I entered a contest on one of the blogs, I guessed 8-4-1.

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s