Hurricane Fiona will undergo a meteorologically spectacular and rapid transition from a hurricane to a hybrid superstorm this afternoon, resembling a powerful nor'easter with a hurricane-like core. Please see for expected impacts.
Very concerned for Ft. Myers metro area. Increasing likely that some of the greatest surge will be focused there, or somewhere close to there, due to maximized onshore flow and concave shape of the coastline.
The last several runs of the HWRF have had a pretty consistent signal for Sally undergoing RI beginning late Sunday into Monday. There are some signals that support this possibility. (1/5)
Fiona may be playing a direct role in amplifying the wave behind it via Rossby wave radiation toward Fiona's SE. The zonal separation (~1800 km) is consistent with such a mechanism, as studied in
@benschenkelwx
(2016, 2017).
Hurricane Beryl has been tenacious against the increased shear. Despite looking more disorganized, the shear has only caused a little weakening. Why hasn’t shear been more effective at weakening Beryl? (1/n)
Ian is quickly gathering strength in the Gulf of Mexico:
1) Well defined eye and mesovortices swirling around within the eye
2) Rapidly falling pressures sampled by recon. aircraft
3) Ring of lightning in the eyewall
All of these are signs of a very dangerous hurricane.
Lots of frustration being inappropriately directed by public at NHC, because some in public think they are responsible/represent the NOAA statement. NHC is not responsible for statement, and NHC forecasters are completely credible. Please trust them to inform and warn you.
The weather community is strongest when public, private, & academic sectors work together to advance science & forecasting. AccuWeather leadership used very poor judgement in its stunt to prop up its brand, at the expense of the trust of the other sectors, in this difficult time.
Based on the radar presentation and hints of a secondary wind maximum appearing in the latest reconnaissance flight legs, it appears that an eyewall replacement cycle is beginning. Ida has likely peaked in intensity.
A couple of ventilation pathways might be at play that have weakened Lee: 1) radial pathway upshear and 2) downdraft pathway in the mesoscale descending inflow of the stationary band complex. Additionally, the first pathway can lead to low-level outflow upshear.
Hurricane Beryl is facing more hostile conditions ahead as wind shear picks up tonight and tomorrow. As a result, multiple runs of the HAFS-B have been showing rapid weakening on Tuesday. Let's take a look via the AOML Model Viewer. (1/n)
I believe we’re seeing the initial signs, via TDR analysis, of shear starting to affect Beryl. Distinct updraft-downdraft asymmetry has developed in the eyewall. Radial flow asymmetries are also becoming more pronounced. If trends continue, weakening should commence soon.
Latest NOAA TDR profile analysis continues to show deep, strong downdrafts on the upshear side of the eyewall exceeding -5 m/s (circled below). Dry air is eroding the W side of the storm too. A lag in the intensity response, but the structural signal for weakening is there.
Ingredients are in place for an intense snowband from C PA, Catskills, Capital District, S VT, S NH. Near Albany, strong frontogenesis and upward motion will intersect the dendritic growth zone between 600-500 hPa. Hefty accumulation rates likely under this snowband tonight.
18Z COAMPS-TC ensemble has a very strong signal for rapid intensification for Idalia in the Gulf of Mexico. Concern is certainly increasing and warranted for FL.
Very impressive rainfall totals already in the Santa Monica Mountains and upwind locations like UCLA, where rainfall rates are close to 1” per hour. Much more rain to come unfortunately.
NHC: "This is an extremely serious situation for the Acapulco metropolitan area with the core of the destructive hurricane likely to come near or over that large city early on Wednesday. There are no hurricanes on record even close to this intensity for this part
of Mexico."
Substantial environmental changes over the next couple of days around Henri will lead to more favorable conditions for intensification, with implications on Henri's eventual track. 🧵 (1/7)
Wishing John Molinari, one of the great scientists in tropical meteorology, a happy retirement. I am so appreciative of John being on my PhD committee, back when I was a graduate student at MIT, and being a great colleague at UAlbany.
Additionally, large arc cloud and lack of any cumulus in its wake (see my attempt to annotate below) suggest substantial downdrafts and low-level divergence interfering with intensification.
That said, the storm does not look particularly healthy. The VDM notes a max flight level temp outside of the 5 nm core, and the data stream shows no real temp spike at all. Pressure has remained stable. Convection cannot seem to sustain and wrap. Still a lot of work to do.
Congrats to Dr.
@JoshuaAlland
on defending his PhD dissertation.
@ProfCorbosiero
and I are very proud academic parents today. Josh made this incredible painting for us.
Florence's direction and how much of the circulation is over water vs. land Fri.-Sat. will be critical to surge impacts. A track like the ECMWF that remains offshore will prolong surge over multiple high tides and could promote a coastally-trapped Kelvin Wave that enhances surge.
After 17 years of forecasting in NCWFC/WxChallenge, it's time for btangy to retire from this forecast competition and move on to bigger challenges. It's been fun.
Forecasted upper-level pattern is conducive for Laura's rapid intensification in Gulf of Mexico. Shear is low, and there are poleward and equatorward outflow channels, facilitated by a upper-level trough to the NW & cutoff to the SE. Question is how fast inner core can organize.
A thing to watch for on Friday is whether Ida undergoes downshear reformation. The 18Z HWRF forecasts this scenario to occur. Downshear center reformations are difficult to anticipate and can cause track shifts.
A feature to watch for Fri. is the formation of an intense, deepening mesoscale low at the spearhead of +PV advection/tropopause fold. 12Z ECMWF suggests this possibility. Such features can have very intense squalls associated with their strong dynamic lift & isallobaric winds.
Isaias' eyewall degrading this evening. Upshear dropsondes by the G-IV show very dry layer of air around 500 mb (5% RH!). Sustained intensification unlikely with upshear environ. that dry and moderate shear continuing.
Prolific day of supercells and tornado warnings across much of NY. Uncommon to see so many long-track supercells in this region.
@RLazear
and I chased one in the Mohawk Valley.
Chased this spectacular isolated supercell with
@btangyWx
this evening, from Bridgewater, NY in Oneida County, all the way northeast to Dolgeville, NY, in Herkimer County. The number of discrete supercells marching across New York State today was pretty unreal.
Seeing a swath of 2-3" per hour snowfall rates in the Hudson Valley and Southern Tier. Rates picking up quickly in the Capital Region. H/t
@nysmesonet
and
@NickPBassill
.
A serious hazard from Ian will be extreme rainfall. The threat of flooding from heavy rain will extend far inland due to 1) slowing of Ian's forward motion, 2) shear-induced lift, and 3) interaction with a frontal boundary. 00Z GFS is forecasting eye-opening numbers >40"!
Models have had a northward bias in Fiona's position at 24 and 48 h forecast times thus far, as others have noted. Additionally, GFS, HWRF, CTCX have been too slow. ECMWF and CMC have been too fast.
Hurricane Otis has the hallmarks of a very intense tropical cyclone, including an enveloped eyewall lightning signature. Landfall near Acapulco is hours away.
Looking at the last 5 GFS forecasts verifying at 18 UTC today, this upper low has trended stronger & less negatively tilted, perhaps influenced by outflow from Hurricane Nora. I suspect this trend is responsible for Ida having a bit more of a NNW motion, rather than NW. (2/2).
The CHIPS model, which (I think) is useful in favorable environments like Delta is in and for the relatively compact, symmetric structure that Delta has, has Delta intensifying to 150 knots before landfall in the Yucatan. Yikes!
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18Z HRRR continues to suggest a long-duration, high-impact heavy rainfall event for NYC metro area, LI and CT. Strong low-level convergence of moist, unstable air, aligning with deformation/frontogenesis, could lead to prolific rainfall totals tonight through Sat. AM.
Ensemble mean and envelopes from the ECMWF, GFS, and UKMET all tell the story of increasing confidence of Henri's more westward track and impacts to LI/S New England. UKMET has been remarkably consistent.
The vertical wind shear affecting Hurricane Lee rises into the moderate range Fri. Compact and intense storms, like Lee, can be very sensitive to changes in shear. (1/4)
Like with Laura, we are again faced with the possibility of a tropical cyclone undergoing RI as it approaches the coast 😬. Hopefully Sally doesn't. Regardless, the forecasted slow movement will be problematic for surge and flood hazards. (5/5)
Hurricane Ida will be moving over a warm eddy that contains the highest ocean heat content anywhere in the North Atlantic this afternoon and tonight. This large reservoir of high-octane fuel will power and likely help rapidly increase the winds of Ida.
The lightning encircling the eye of Ian is just jaw dropping. Additionally, there are some extreme radar velocities appearing aloft. Extreme wind damage likely as the eyewall moves ashore.
Debby's moisture will combine with an anomalously strong trough late this week to produce prolific rainfall amounts in the Northeast. Dynamic tropopause (h/t
@AliciaMBentley
) shows a tropopause polar vortex (TPV) coming out of Canada while Debby meanders near the Carolinas. (1/)
The coldest cloud tops have rotated upshear with intermittent inner-core lightning upshear too, both signatures of intensification (now rapid) in Hurricane Ida. The hopes of a disorganized inner core being further disrupted by the transit over Cuba are vanishing.
As the sun sets on Hurricane Laura, multiple convective bursts are circling the center, lightning activity is increasing in the inner core, and central pressure is dropping – all signatures of intensification.
As others have noted, Ida is tracking on the eastern side of model track forecasts. One feature steering Ida is an upper-level low in the W Gulf of Mexico, which can be seen on water vapor satellite imagery. This upper-level low is contributing northward motion to Ida. (1/2)
@mattlanza
@wxbrad
It's a bad sign that there is no information about certain areas that likely received the worst of the worst. I have a feeling we will be seeing pictures similar to Mexico Beach after Michael and Bolivar Peninsula after Ike. Hope I'm wrong.
Grace looks better organized on Guadeloupe radar. Precipitation is now enveloping the center. Convection continues to be strong and sustained upshear. These are indicators for intensification, perhaps rapid. We'll know more soon with reconnaissance.
12Z HWRF has a reasonable depiction of Laura's short-term evolution, with a dominant circulation crossing Puerto Rico. Thereafter, the center jumps around due to convective bursts and interaction with Hispaniola. Messy and tricky short-term forecast.
Got a COVID test today, as I get ready to return to campus in 1.5 weeks. If every UAlbany student has to get one, I personally think all faculty/staff should be advised to get one too. And yes, it made me tear up, but I had coffee after, and I was happy again.
We conducted a 1700 UTC radiosonde launch from
@ualbany
ETEC to sample the local environment ahead of convection moving in from the south, as part of the ICECREAM field project. Not much shear to support severe weather locally, but plenty of moisture for heavy downpours.
Visible satellite and Grand Cayman radar seem to suggest that there is a mid-level center around the location of the red x. Question is where the low-level center is, and how well defined it is, which reconnaissance will provide information about soon.
Beryl's remnants packed a big punch. Radar low-level rotation tracks and NWS tornado warnings showed the impressive extent of supercells across much of NY state.
Satellite intensity estimates indicate Ida is approaching (if not at) Category 4 intensity. AF reconnaissance will provide valuable observations soon to see if that's the case.
Hurricane Lee is sputtering due to continued moderate shear and dry air. While there are episodic bursts of strong convection, they quickly collapse, likely flushing cold, negatively buoyant air down toward the surface. (1/2)
We can look at the tilt of Beryl’s vortex. The tilt of the lower half of the vortex points in the upshear-left direction. An upshear-left tilt is associated with more convection upshear and the vortex trying to realign. (2/n)
Another possible factor is the anomalously large ocean heat content in the Caribbean, which is blunting any effects of downdrafts by quickly restoring the energy and buoyancy needed to sustain convection in the eyewall. (4/n)
Dorian's inner core is looking healthier this afternoon. Convective bursts are moving upshear with intermittent lightning. This pattern, if it can persist, can herald intensification.
Indications are that shear is winning out in weakening Hurricane Beryl this evening. What are these indications? The tilt, diagnosed by TDR analyses, has increased toward the downshear-left direction. (1/)