*******Note that forecasts and outlooks in this post are NOT the official forecast from the National Hurricane Center (NHC). They are my own detailed views on the Atlantic tropics based on current observations and latest computer model runs. As such do not make decisions based on my posts...consult news media...watches and warnings from your local weather office...and any evacuation orders issued by local governments to make the most informed and best decisions. Visit the NHC website hurricanes.gov (hurricanes dot gov) for the latest watches/warnings and official forecasts on active tropical cyclones.**********
...TUESDAY MAY 10 2022 9:53 PM EDT...
Although Atlantic Hurricane Season does not officially start till June 1st… continuing daily birdseye view posts as we continue to monitor the deep-layered low pressure offshore of the eastern United States for acquisition of tropical characteristics. Regardless of whether or not the surface low pressure acquires tropical characteristics… it has already been bringing impact to the mid-Atlantic and northeastern United States coast. See area of interest #1 section below for more details.
AREA OF INTEREST #1… Colorized infrared satellite image of the deep-layered low pressure of interest located offshore of the eastern United States… taken at 0101Z. Red plus marks the observed surface center of the low pressure. Yellow plus marks the upper level vortex center of the low pressure… which may have recently developed its own surface center according to recent ASCAT passes:
A deep-layered low pressure system offshore of the eastern US coast remains cut-off from the mid-latitude westerlies by a deep-layer ridge passing to the north. The result is it remains quasi-stationary… and will continue to monitor this system for acquisition of tropical characteristics for the remainder of this week. The deep-layered low pressure system continues to consist of an upper vortex parked over a decaying surface frontal low. The defined surface center of the frontal low that we have been tracking since yesterday has (as expected) whirled south to 32.5N-71.5W while steered by the west side of the upper vortex center established at 35N-70W. In addition to satellite animation…. this surface center was confirmed by a recent ASCAT-C descending satellite scan of surface wind (https://manati.star.nesdis.noaa.gov/datasets/ASCATBData.php). Recent ASCAT-B and ASCAT-C ascending passes have also suggested a second surface center near 35N-70W… directly below the center of the upper vortex.
An impulse associated with the current western Canada upper trough regime has produced a surface frontal cyclone that has recently swung north into central Canada… and together are weakening the blocking southwest flank of the deep-layer ridge. This will allow the remainder of the deep-layer ridge to push the circulation at 35N-70W on a west drift in the next 24 hours. Given that this circulation has a surface component as noted in the previous paragraph… it is reasonable to assume the other surface center at 32.5N-71.5W could drift northeast in the short- term and merge with it. Thus my updated forecast track points are nudged north and east relative to my previous forecast…. which also brings the updated forecast in alignment with the latest model runs. After 24 hours… the track is expected to bend west-southwest around the southwest lobe of the deep-layer ridge… bringing this system into an eventual landfall most likely on the Georgia or southern South Carolina coast.
I have dropped the 24-hour odds of subtropical cyclone formation to 0% as the deep-layer low has multiple competing surface centers. Given the possibility of the centers merging into a single center needed for subtropical development… and this system passing over warm Gulf Stream waters.. I raise odds of subtropical development to above zero by 48 hours. However I have only 10% development odds as there is no guarantee the two surface centers merge into a well-defined one… and today’s model runs are more gung-ho when it comes to weakening the surface circulation beneath the core of the upper vortex (where upper divergence is lacking). This implies the surface circulation may be too weak to take advantage of the warm waters by the time it reaches them.
Regarding impacts to land areas:
(1) A tight surface pressure gradient remains set up between the north side of the surface low and south side of the adjacent deep-layer ridge. This is driving a strong toward-shore wind and ocean flow for the northeastern and mid-Atlantic US east coast. Sea swells… rip currents… and gusty winds will continue here through tomorrow.
(2) For the southeast US coast… an area of heavy rain affecting a small region may develop Thursday or Friday should this system see an increase in thunderstorms or develop into a weak subtropical cyclone (subtropical depression for example)
******Infohurricanes.com outlook. Visit hurricanes.gov (hurricanes dot gov) for official outlook***********
IOH 24 Hr Outlook (1800Z May 11)… 0% chance of subtropical cyclone formation (offshore of the Carolinas near 33N-73W)
IOH 48 Hr Outlook (1800Z May 12)…10% chance of subtropical cyclone formation (offshore of Georgia and South Carolina near 32N-77.5W)
IOH 72 Hr Outlook (1800Z May 13)…0% chance of subtropical cyclone formation (just west of the Georgia/South Carolina border near 32N-81.5W)
...COMPUTER MODEL SUMMARY...
Source...Florida State University Experimental Forecast Tropical Cyclone Genesis Potential Fields (http://moe.met.fsu.edu/tcgengifs/)
1200Z CMC Model Run...
**For area of interest #1… surface low wobbles west while slowly weakening and shrinking… dissipates just offshore of Cape Fear North Carolina at 54 hours
1200Z ECMWF Model Run...
**For area of interest #1…surface low wobbles west-southwest while slowly weakening and shrinking… dissipates just offshore of Georgia at 72 hours
1200Z GFS Model Run...
**For area of interest #1… surface low weakens to a westward-drifting surface trough at 76W longitude at 45 hours… trough makes landfall on Georgia coast at 78 hours
1200Z NAVGEM Model Run...
**For area of interest #1… surface low wobbles west and weakens to a trough just offshore of the Carolinas at 48 hours… trough moves southwest into Georgia coast by 72 hours