JAN. 03, 2013…10:25 A.M. EST:
Since the SPC does not indicate any severe weather threat over the next 3-5 days, and the current pattern should remain through the weekend, I will be leaving the pre-season hurricane forecast in place to give folks who have not seen it, a chance to do so.
Good day everyone!
This is a pre seasonal forecast for the upcoming 2013 Atlantic Hurricane Season.
Please bear in mind, the totals listed will change, as some of the forecast parameters become clearer (i.e. Onset of a supposed El Nino, NAO strength affecting the current AMO, past ONI conditions update to utilize as analog years, etc.).
Two of the biggest factors that will determine how active a season we may see, are whether or not we could switch to predicted El Nino conditions as summer onsets, and whether the NAO goes negative and hangs that way for the the spring into the summer, allowing the AMO to remain warm. Currently, the NAO is forecast to be in the positive for most of the month, with a drop toward neutral indicated. Should the NAO remain positive, it will allow for stronger trades across the MDR and cool the area more. The current SST anomalies in the Atlantic MDR are running 1.0C – 2.0C above average. The opposite happens during a negative NAO phase. As far as ENSO forecasts, the CFS long range model is indicating the onset of El Nino come spring of this year, which we know suppresses Atlantic Hurricane Activity by affecting vertical wind shear in the Atlantic. However, two of the best analogs I can use at the moment, had ONI (Oceanic Nino Index) values warming to neutral warm bias, to El Nino conditions during AMJ in one year, and JJA of the other. One season produced 12 storms, the other 15 storms. This is going to be the trick and will have to be monitored in order to revise forecast values, as the models did not handle the projection of a FULL El Nino for the 2012 season, as we were neutral warm bias at best, with the Atmospheric/Oceanic coupling not occurring. Along with that revelation models seem to be split at the moment as to whether or not an El Nino will develop. However, I was a little surprised to end up with a total of 19 named storms in that type setup, and is pretty much an anomaly based on previous seasons with the same setup.
CURRENT NAO FORECAST
RECENT SST ANOMALIES
CFS FORECAST SST ANOMALIES
ECMWF SST ANOMALIES
VARIOUS MODELS NINO PLUMES 3.4
Based on long range seasonal forecast from both the CFS and ECMWF, it currently appears that the MSLP anomalies for the Atlantic become normal, to slightly below average as we enter the season, which if correct, could be supportive a more negative NAO.
CFS 850 MB ANOMALIES
ECMWF MSLP ANOMALIES
Other values I use in my formula for storm total and hurricane calculation, are based on what the current SST’s are mainly in the Caribbean, current depth of the 26C temperature contour, (50 METER DEPTH REQUIRED) and GOMEX, and projected TCHP using past years.
26C ISOTHERM DEPTH
Again, as more of these parameters become clearer, I will be updating around MAY/JUNE of this year for a more accurate forecast. Another factor which is essentially unknown is whether or not we will see another barrage of dry air as we did this past season. IF the ENSO phase stays relatively cool, we should see a little more aid from the MJO.
Based on all the information at hand currently, and information provided by Dr. Phil Klotzbach, et.al, I have come to the following totals for the 2013 Hurricane Season:
Total Named Storms: 14-15
Total Hurricanes: 7-8
Intense Hurricanes: 3-4
Again, I will be updating later this year.
Have a blessed day!
T. F. “STORM” WALSH III
GMCS, USCG (ret)
METEOROLOGIST / HURRICANE SPECIALIST
MEMBER WEST CENTRAL FL AMS
CERTIFIED SKYWARN OFFICIAL STORM SPOTTER (advanced)