FRIDAY, 28AUG15 / 3:20PM CDT
A DEDICATED UPDATE ON ERIKA IGNACIO AND JIMENA WILL
BE ISSUED SUNDAY AFTERNOON – THERE WILL NOT BE AN UPDATE TOMORROW!TROPICAL STORM ERIKA REMAINS A THREAT TO FLORIDA WITH HURRICANE IGNACIO NOW A THREAT TO HAWAII
Minimal Tropical Storm ERIKA is estimated near 17.2˚N/69.5˚W – about 60NM SE of Santo Domingo, Dominican Republic (based on SAT imagery and recent RECON fixes that do NOT really match up with NHC advisories). MAX sustained winds are barely of minimal Tropical Storm intensity of 40Kts (more likely near 35Kts) – mainly to the East of the surface center which remains well to the NW of convection.
Wind shear of over 20Kts continues to prevent the cyclone from intensifying, and with the storm system about to traverse the very high, mountainous terrain of Hispaniola – the odds of ERIKA surviving as a tropical cyclone continues to be quite low (down to a probability of 30% from 35% mentioned in my late afternoon post yesterday.) The only reason that the system still has a chance of remaining as a cyclone over the weekend is the improving very high level outflow centered above the storm system, and the more favorable environmental conditions ERIKA should encounter to the north of the CARIB Islands, including lower wind shear of 10-15Kts by Sunday, very warm SST’s and additional divergence aloft just ahead of the cyclone from the unseasonably deep upper level Low/TROF that should still be near the north central Gulf coast.
However, as now reflected in the NHC forecast – the system will still find it quite difficult to re-intensify as it is expected to move close to and parallel to the north coasts of Haiti and Cuba before it turns Northwestward later Sunday.
Again - ASSuming the cyclone still exists when it approaches south Florida Sunday - it will be very difficult for the cyclone to intensify into a Hurricane based on the latest Track forecasts as the system will be interacting with the Florida landmass - and while upper level winds are still going to be favorable for intensification, the latest global model forecasts are NOT as favorable as they were yesterday. Still, looking out beyond 3-5 days is quite problematic for both Track and Intensity forecasts – so the system still needs to be closely monitored as long as remains a viable cyclone.
HURRICANE IGNACIO THREATENS HAWAII
Hurricane Ignacio about 650nm SE of Hilo is dead-reckoning for the Big Island as a strong CAT 1 – but track forecasts that have been quite consistent for the last few days - the storm should begin to recurve north of the Islands just prior to the time it will be arriving in the vicinity of the Big Island Monday. The Hurricane is in a very favorable environment for additional intensification, and could reach strong CAT 2 strength tomorrow - but will encounter decreasing SST’s and much more importantly - increased wind shears on Sunday and Monday, which should then lead to a slow but steady weakening to a CAT 1 storm by the time it is passing north of the Big Island later Monday. A more detailed overview of the storm will begin SUNDAY.
HURRICANE JIMENA *NOT* SEEN AS THREAT TO HAWAII BUT
MAY EVENTUALLY IMPACT THE WEST COAST OF NORTH AMERICA Hurricane JIMENA - which based on latest SAT imagery is now a CAT 2 hurricane - is located about 1,100NM south of Baja California – heading due west. The storm is in an extremely favorable environment for intensification, and will likely reach Major CAT 3 intensity by tonight – and CAT 4 tomorrow. By SUN, the upper level ridge that extends from NW Mexico westward to north of the storm should start weakening as a deep upper level TROF begins to dig southward off the west coast of North America. This should eventually lead the storm to start recurving to the NW, tracking over progressively cooler waters next week with slow but steady weakening.
Longer range GFS forecasts have been calling for the storm system to recurve to the north in about a week and then northeastward towards the west coast of North America. Forecast tracks have varied quite a bit over the last 3 days, with some forecasts calling for the storm to turn towards northern California by 10-14 days out, others towards Seattle – and the most recent - towards British Columbia. Keep in mind SST’s are far too cold for the system to remain as a Hurricane, but interacting with the cold, upper level TROF and associated baroclinic forcing imply the system will be a prodigious wind and rain maker – wherever it ends up.
STRONG TROPICAL WAVE / TROPICAL LOW EMERGING OFF WEST AFRICAN COAST
The very strong T.W. I mentioned a few days ago when it was over central Africa is now emerging off the west African coast with a strong, low level circulation. This system could be designated as a tropical cyclone by NHC tomorrow if it maintains it’s convection and circulation. However, the latest GFS forecasts calls for the system to eventually turn northwestward and out to sea next week.
IMPORTANT NOTE: WITH POTENTIALLY 3 TROPICAL CYCLONES TO FOLLOW – US AND ALASKAN TEMP FORECASTS AND COVERAGE OF EL NIÑO WILL * NOT * BE PROVIDED UNTIL AFTER THE PRIMARY THREATS TO THE US ENDS.
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Fig 1: Visible (left) and Microwave (right) images of ERIKA This morning’s VIS image from this morning combined with the MW image and RECON data continue to show the Low Level Circulation Center (LLCC) remains well to the west/northwest of the main convection. The same data reveals a very poorly organized storm – primarily the result of continuing 20Kt+ wind shear. The LLCC is also to the left of the ‘official’ NHC position – though this doesn’t really mean too much at the current time due to most of the convective weather and gusty winds remaining to the east of the LLCC.
Fig 2: Satellite Derived Wind Shear analysis from CIMSS. Note the 2 different positions plotted by CIMSS – showing the ‘jump’ in the location of the LLCC. (The left most position is the CORRECT position!) Westerly Wind shear remains over 20Kts’ and is primarily responsible for the convection remaining well to the E/SE of the surface center. How well the models will handle the movement of the surface center and convection across Hispaniola will play a major role in determining if ERIKA remains a viable cyclone after moving north of the Island this weekend. Shears should decrease as the storm moves north of Hispaniola, falling to around 15Kts Saturday and possibly to 10-15Kts Sunday. .
Fig 3: Upper Level Wind analysis from CIMSS from this AM highlights the upper level anti-cyclone that has migrated to directly above the centroid of ERIKA’S circulation field. As ERIKA moves north of Hispaniola tomorrow, it will continue WNW thru Sunday before turning Northwestward and eventually Northward as it rounds the western end of the upper level ridge near 32˚N latitude and 60˚W longitude. Assuming ERIKA remains a viable cyclone on MON, the upper level TROF now in the south central US/Central GOM region will play an increasingly important role in the track and intensity of ERIKA early next week, with the southerly flow in the eastern GOM ahead of the TROF governing the track of the cyclone.
Fig 4: Early Cycle Tropical Cyclone model forecasts for ERIKA The forecast tracks continue to call for ERIKA to track WNW towards the Bahamas – paralleling the north coasts of Hispaniola and Cuba before turning NNW near Florida. With the current further west location of the cyclone, all the tracks have shifted towards the west. Intensity forecasts primarily keep the system as a Tropical Storm – with a few typical outliers still calling for strong intensification if the storm takes a track east of Florida – which at this time – doesn’t appear likely.
Fig 5: Tropical Cyclone Track and Intensity Forecast chart for ERIKA from the US NAVY AND MY OWN TRACK FORECAST The last available track and intensity forecast for the next 5 days (which follows the NHC forecast EXACTLY for all ATL and EPAC hurricanes) has continued to follow the model consensus for the track and the lower end of intensity forecasts.The BIG question, of course, is whether the storm will even exist as a viable cyclone after it emerges north of the CARIB Islands. I’ve overlaid my own forecast which more closely follows the 12Z GFS forecast, with a track further west with a slower forward movement due to the further west 'starting position'.
Fig 6: Combined Enhanced IR image and Wind shear analysis by CIMSS from this morning shows a very well-organized Hurricane with a symmetrical convective cloud shield. Cloud top Temps are near -75˚C, implying T-storm tops of 50,000’ in this area of the world. Wind shear of 5-10Kts is very favorable for additional strengthening – and the storm is likely to reach CAT 2 intensity by tomorrow.
Fig 7: Early run of Tropical Cyclone model forecasts for IGNACIO look quite reasonable – but of course become less reliable beyond 3-5 days out. However, all track forecasts turn the storm center to the north of HILO – with gradually weakening intensity forecasts due to lower SST’s and expected increases in wind shear before the storm nears the Islands.
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Fig 8: Tropical Cyclone Track and Intensity Forecast chart for IGNACIO from the US NAVY. The track and intensity forecasts follow the model consensus forecasts, with the storm expected to pass about 100NM north of Hilo and 150NM of Honolulu as a CAT 1 storm on or around Tuesday. With the Islands on the south side of the storm – MAX winds are not likely to be over 50Kts on the Big Island even if IGNACIO is still a moderately strong CAT 1 Hurricane. But obviously, this will change if the storm passes closer to the Islands.
Fig 9: IR (Infra-Red) Image of Intensifying Hurricane JIMENA from this AM shows the rapidly intensifying, CAT 2 Hurricane which is tapping into the deep tropical moisture to its south near the equator! The storm is quite likely going to reach CAT 4 intensity during the next 24 hours. (Note the eye was already becoming visible early this AM. )
Fig 10: Water Vapor Image of JIMENA also showed the clearing of the eye – typical of CAT 2 Hurricanes.
Fig 11: Early cycle Tropical Cyclone model forecasts for Track and Intensity for JIMENAThe forecast tracks are tightly clustered on a generally westerly heading for the next 2 days before beginning a gentle recurvature towards the NW next week. After a likely rapid intensification phase during the next 24 hours – the storm will gradually weaken next week as it moves over progressively cooler waters. The wide differences in the intensity forecasts are typical of a storm undergoing a rapid intensification cycle.
Fig 12: Tropical Cyclone Track and Intensity Forecast chart for JIMENA from the US NAVY The latest available track and intensity forecast for the next 5 days (which follows the NHC forecast EXACTLY for all ATL and EPAC hurricanes) are in close agreement with the model consensus for the track – but maintains an intensity greater than the model consensus in deference to the current rapid intensification phase the storm is currently undergoing.
Fig 13: LOW LEVEL wind analysis from CIMSS over Africa shows the very strong low to mid-level closed circulation around the strong Tropical Wave/Low just now emerging off the west African coast. The latest GFS forecasts call for this system to eventually track out to sea next week, however.
Fig 14: Two- Day imagery Loop across north Africa. The loop begins with the strong system in central Africa 2 days ago (when I first reported it) - ending just as the system was coming off the coast this morning.
✭ A DEDICATED UPDATE ON ERIKA & HURRICANES IGNACIO & JIMENA ✭
WILL BE ISSUED SUNDAY – THERE WILL NOT BE AN UPDATE TOMORROW (SATURDAY)!✭Want to be alerted when I post an Update? Then follow me on Twitter!
Steve
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