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** No direct *inland* impacts expected from Fiona for Jacksonville/NE Fl./SE Ga.... beaches to be affected by easterly swells, rough seas/surf & a high rip current risk mid through late week.... **
Tropical wave - ‘96-L’ was upgraded to tropical depression #7 Wed. morning then to tropical storm “Fiona” Wed. evening. Fiona has been battling a narrow but significant - 30-40 mph - band of westerly shear to its immediate west & northwest has been causing much/almost all of the shower & t’storm activity to stay over the eastern portions of the circulation. But storms started wrapping around the center Fri. evening as the storm organizes & subsequently strengthens. The center may still “jump around” some until the center is completely & strongly wrapped with convection allowing for the low level center to align with the mid & upper level centers. Upper level outflow has increased as well indicating better “ventilation” is becoming established & outside of land interaction, Fiona should be steadily strengthening this weekend. Of note - the center moving a little south of due west into the face of the shear - as was the case Wed./Thu. - has led to eventually powerful tropical cyclones which Fiona could become, most likely - in the longer range. Fiona has recently taken on a more due west course with the closest approach to Puerto Rico Sat. night into early Sunday then to near or over the Dominican Republic Sunday night-Mon.
* Puerto Rico & U.S. Virgin Islands/nearby Caribbean islands: Heaviest rain, strongest winds & most severe seas late Sat. through Sun. with improving conditions Sun. night-Mon.
* Most intense impacts for Hispaniola late Sun. through Mon. Strongest winds will impact Dominican Republic along with flooding rains... Haiti will subject to some heavy rain & flooding but winds look to be much less
* Impacts to the Southeast Bahamas Mon. night through Wed.
* Possible impacts for Bermuda late in the week
* Possible - but still subject to major changes - impacts for Nova Scotia next weekend
* Increasing swells/seas/surf + dangerous rip currents for virtually all of the U.S. east coast during the upcoming week (but Fiona well offshore)
Forecast models briefly trended more west Thu. but have trended back east recently which is why one should not become too obsessed with individual model runs. Some of the real time aircraft dropsonde data was used Thu. in the 18Z (2pm) GFS model run *but not* in the 00Z (8pm) model run which is probably why the GFS had a “hiccup” in the 18Z run showing a track much more west. I bemoan when real time data is not consistently used within the models as it usually causes inconsistency within the models. Either use it with reach run as long as it’s available or don’t use it at all. The good news is that Gulfstream G-IV research aircraft will go into use Sat. & hopefully will continue consistently through next week with the data gathered from the atmospheric environment in & around Fiona then can be used to initialize the GFS for each run. This would help with better initial analysis for models at the beginning of the forecast cycle which would then - in theory - give more accurate output (forecast). The good news is that both the GFS & European models have generally been initializing/starting with a reasonable & accurate depiction of Fiona & its strength/location so far. Clustering & consistency of the models has recently improved with a definite trend east of the U.S. mainland. The GFS remains a little faster than the European model... the UKMET appears to her out to lunch.
In any case... the historically more reliable models remain in better general agreement as the GFS is back to where it’s been all week - a powerful hurricane well east of Fl. mid to late week & staying east of the entire east coast of the U.S. The European model has trended east too though still slower, & now has even joined the “party” in taking Fiona far to the east of the entire U.S. east coast but is more north & northwest late in the wee/next weekend which has implications for Nova Scotia. The UKMET model - which I like to generally consider when there is great disagreement among the models - is still showing a relatively weak Fiona through next week far to the east of Fl. From an intensity standpoint in particular, the UKMET is an outlier (big time).
The westerly shear + somewhat dry air nearby have been the primary reasons for Fiona’s struggles the past several days. It is worth noting Fiona still managed to produce strong & persistent convection despite less than ideal conditions. Overall environmental conditions are gradually improving near Fiona over the weekend into next week, so Fiona may become a hurricane sooner rather than later. A hurricane over the Northern Caribbean, Puerto Rico & the Dominican Republic is now a distinct possibility. The big caveat early in the week will be eventual possible land interaction - especially the mountainous terrain of Hispaniola.
On the current official forecast track, Fiona will move near or a little east of some of the highest mountain ranges of Haiti & the Dominican Republic. It’s this part of the forecast - Puerto Rico & Hispaniola - that right now is the most critical - the “fork in the road” when it comes to strength & track once over the SW Atlantic given the track over land could seriously disrupt Fiona’s organization. The two most major steering influences otherwise will be: (1) the Bermuda high (clockwise circulation) which remains well to the northeast over the Atlantic but may try to flex its muscles some later next week... & (2) the strength of Fiona - weaker is longer to the west steered more by low level flow (trade winds)... stronger will be faster to make the turn more northwest then north (steered by mid & upper level flow).
From the Greater Antilles, forecast models continue to trend northward next week with Fiona which seems reasonable though how sharply to the north - & when - is still up for some debate. The model spread has - for the most part - narrowed. The European model continues to take a weaker Fiona just about due west a little south of Puerto Rico then over Hispaniola before turning more north while intensifying once near the Central/Eastern Bahamas before slowing & turning north then northeast. The GFS model takes a slowly strengthening (stronger than most other models) Fiona near/just south of Puerto Rico then starts to turn Fiona north early enough/fast enough to mostly avoid Hispaniola to the immediate east through the Mona Passage (between Dominican Republic & Puerto Rico). This path would mimic Matthew in 2016 (in the short term!) which shot through the narrow (only about 80 miles) strait of ocean with few impacts from land. I still favor the track well east of Florida which is the trend indicated in the models as well.
Overall - once away from the Greater Antilles/Leeward Islands - it looks like conditions (water temps., shear & moisture) will favor strengthening next week. It *appears* Fiona will stay far to the east of Florida & most of the U.S. east coast, but we shouldn’t let our guard down & check & re-check the First Alert forecast.
Another interesting forecasting tidbit... a typhoon over the W. Pacific is turning sharply to the north then northeast impacting Japan this weekend (track map at the bottom). This typhoon teleconnection might correlate rather well with Fiona over the W. Atlantic next week & the rather sharp turn north & - in time - northeast. This correlation is possible because of the upper level pattern - troughs (dips) & ridges (upside down U’s) in the jet stream - that often (not always) mirror each basin (Pacific & Atlantic). See maps 6 & 7 below.
So to recap: Fiona is a storm that will have serious impacts on the Northern Leeward & virtually all of the Eastern Windward Islands of the Caribbean (no direct impacts to Cuba) through the weekend with very heavy rain & strong winds with flooding & possible mudslides... then eventually at least some impact on some of the Bahamas Tue./Wed. - especially the Turks and Caicos Islands - followed by a move more north & - finally - north/northeast. The details for next week are still subject to change. We’re still in the early stages of a tropical cyclone that is just getting its act together.
Elsewhere... a couple of pretty strong tropical waves are over the Eastern Atlantic with at least some potential for slow development. A more southern latitude wave just off the African coast may try to chug its way westward through next week.
Some weak low pressure is developing over the Western Atlantic to the east of the Carolina’s & E/NE of Jacksonville in response to an upper level trough. The low should move slowly east/southeast embedded within strong shear that will likely hinder development & there may some interaction with Fiona mid to late week.
Spaghetti plots including the ensemble (faint lines showing all the model runs which gives an indication of the uncertainty):
Mountainous terrain over especially the Central & Western portions of Hispaniola with some peaks 10,000+ feet:
Image Courtesy: NASA/JPL/SRTMImage
Possible upper level (about 30,000 feet) teleconnection with troughs & ridges between the Atlantic (steering Fiona) & the Pacific (steering W. Pacific typhoons):
San Juan radar:
Water vapor loop shows some dry air near wave ‘96-L’, but it’s more moist than past days:
A strong zone of shear - on the order of 30-4+ mph - has become oriented more east/west just north of Fiona. Forecast models gradually decrease this shear & narrow the “zone” to the north & east.
Friday night recon mission:
Thursday recon mission:
Averages below based on climatology for the Atlantic Basin through September. This season so far is well below avg.:
Saharan dust spreads west each year from Africa by the prevailing winds (from east to west over the Atlantic). Dry air - yellow/orange/red/pink. Widespread dust is indicative of dry air that can impede the development of tropical cyclones. However, sometimes “wanna’ be” waves will just wait until they get to the other side of - or away from - the plume then try to develop if other conditions are favorable. In my personal opinion, way too much is made about the presence of Saharan dust & how it relates to tropical cyclones. In any case, we’ve had several large dust plumes spread west to the Caribbean & Gulf with the peak of Saharan dust typically in June & July.
2022 names..... “Gaston” is the next name on the Atlantic list (names are picked at random by the World Meteorological Organization... repeat every 6 years). Historic storms are retired [Florence & Michael in ’18... Dorian in ’19 & Laura, Eta & Iota in ‘20 & Ida in ‘21]). In fact, this year’s list of names is rather infamous with “Charley”, “Frances”, “Jeanne” & “Ivan” retired from the ‘04 list (all hit Fl.) & “Matthew” was retired in 2016. The WMO decided - beginning last year - that the Greek alphabet will be no longer used & instead there will be a supplemental list of names if the first list is exhausted (has only happened three times - 2005, 2020 & 2021). The naming of tropical cyclones began on a consistent basis in 1953. More on the history of naming tropical cyclones * here *.
Mid & upper level wind shear (enemy of tropical cyclones) analysis (CIMMS). The red lines indicate strong shear:
Water vapor imagery (dark blue indicates dry air):
Deep oceanic heat content over the Gulf, Caribbean & deep tropical Atlantic:
Sea surface temp. anomalies:
SE U.S. surface map:
Surface analysis centered on the tropical Atlantic:
Surface analysis of the Gulf:
GFS wave forecast at 48 & 72 hours (2 & 3 days):
Atlantic Basin wave period forecast for 24, 48 & 72 hours respectively:
Updated Atlantic seasonal forecast from early Aug. - NOAA & CSU:
The East Pacific:
“Lester” is over the far E. Pacific south of the south coast of Mexico. Tropical storm conditions are expected along the coast of southern Mexico between Laguna de Chacahua and Zihautenajo. A Tropical Storm WARNING is in effect for Puerto Escondido to Zihuatanejo... A Tropical Storm WATCH is in effect for the area from west of Zihuatanejo to Lazaro Cardenas.
Global tropical activity:
Strong typhoon “Nanmadol” is over the W. Pacific & will impact much of Japan through the weekend into early next week:
Cox Media Group