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(T. F. “Storm” Walsh III)
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Good evening everyone!
Well, at some point, I have to draw the line, and began transitioning the site and forecasts toward the tropics. Not really drawing a line, per se, but since the season is less than a month away, I feel it necessary to start posting items such as definitions to the various phenomenon and acronyms you see me post during the season, various tidbits of information, as well as preparation items. I will try to include severe weather updates, should hey pose a serious enough threat assessment. It’s just very time consuming, and wearing on me to perform both, in depth, as I am the ONLY forecaster here…LOL!. Since it appears we may have a short break, in which the severe weather risks for the next 2 days are marginal, I wanted to post on something that sparked my attention for the tropics, albeit it may not wind up being anything. However, the possibility always exists.
As I’ve stated previously, I started a couple seasons ago, posting my Tropical Weather Forecast Synopsis, starting May 15. Yes, this date is the start of the Pacific season. However, in the past, development in the extreme W. Caribbean near mid and 3rd week of May has not been a stranger to us., and not to forget, we had “Bonnie” from last season develop off the U.S. coast May 27. By beginning my forecasts on the 15th of May, I can guard against any “crossovers” from the EPAC, in which one surprised me either the last season, or the one prior to that.
With that said, I’ve been analyzing the global modeling on and off over the past 4-5 days, and it appears Mother Nature may try to be right on time in the PAC, or even a little early. The ECMWF has shown over the past couple of days, of a tropical system developing on the EPAC side, near approximately 10.0N;97.0W, in about 5-7 days. As far as formation, the ECMWF has the support of other global models (GFS, CMC, NAVGEM, UKMET, and FIM8), however timing differences are noted. The CPC Global Tropical Hazards Assessment Forecast also suggests EPAC development. Now, I am not very concerned for our side (not that I am not concerned about the Isthmus of Panama, as by day 10, the ECMWF lowers the MLSP to 959 MB), looking at subtleties in motion, and where lowering pressure may occur after 10-14 days, the PAC system may have a SLIM chance at becoming a crossover, into the extreme W. Caribbean. Let me caution you however, this is nothing definite. I will be looking at things over the next few days, and all of this could change between now and 2 weeks out. The ECMWF does suggest, that initial motion will be toward the WNW to NW . By the end of the period (240 hours), the model brings it back toward the WSW and very close, to if not onshore over the Isthmus of Panama.
ECMWF MODEL 144 HOURS
ECMWF MODEL 210 HOURS
The 12Z run of the NCEP /EMC Tropical Cyclogenesis Tracking Page hints at a north to NNW motion from the area it believes development may take place.
The GFS, and CMC (to some extent) hint at a weak low showing up in the W. Caribbean later in the period, and the NCEP 500 MB Mean Anomaly map indicating significant lowering of pressures over Honduras, extending partially into the Gulf of Honduras.
NCEP 500 MB MEAN ANOMALY FORECAST
While I do not believe anything to become organized in the W. Caribbean at the moment, regarding this system, it is noted upper level winds will be favorable for development in the EPAC, with favorable upper level winds shifting into the W. Caribbean for a short period thereafter, nearing day 10-12 in the period from 12Z today. The current CHI 200 forecast (200 mb vertical velocity) also indicates strong upward motion to be in place during this time period.
GFS WIND SHEAR FORECAST
200 MB VERTICAL VELOCITY FORECAST MAPS
Again, this may amount to nothing, however I’d rather not have anymore surprises catch me off guard.
I will begin issuance of my Tropical Weather product on May 15, 2017, and may update my Seasonal Activity Forecast, either by the end of the month, or June 01, 2017, should the updated information from the climate models recent updates hold.
And PLEASE, if you have any questions regarding tropical storms and hurricanes, don’t be afraid to ask here, or on my sites Facebook page:
Have a blessed evening!
T. F. “STORM” WALSH III
GMCS, USCG (ret)
METEOROLOGIST / HURRICANE SPECIALIST /SEVERE WEATHER SPECIALIST
MEMBER WEST CENTRAL FLORIDA AMS