Azores storm could become Subtropical Storm Alberto
An interesting and surprising hybrid low pressure system with both tropical and extratropical characteristics has formed over the far Eastern Atlantic, about 400 miles southwest of the southern Azores Islands. This low, designated Invest 92L by NHC today, has developed an impressive amount of heavy thunderstorm activity near its center, despite the fact that it is over cold ocean waters with temperatures of 66°F (19°C.) This is well below the 26°C usually needed for a tropical storm to form. However, there is quite cold air aloft, so the temperature difference between the surface the upper levels has been great enough to create sufficient instability for 92L to organize. Wind shear is a moderate 15 - 20 knots, and satellite estimates of 92L's winds were 63 mph at 1:45 pm EDT Saturday, according to NOAA/NESDIS. NHC estimated that 92L had top winds of 50 mph at 2 pm EDT Saturday.
Figure 1. Afternoon satellite photo of Invest 92L, taken at 16 UTC May 12, 2012, by NASA's Aqua satellite. Image credit: NASA.
NHC is giving 92L a 40% chance of developing into a named storm by Monday. They will be reluctant to name it Alberto unless the storm can maintain it's current level of heavy thunderstorm activity for at least 6 - 12 hours. The storm's heavy thunderstorms have weakened some during the afternoon, making it less likely NHC will be inclined to name it; the fact that 92L is over waters of 66°F (19°C) hurts its chances. The coldest waters I've seen a tropical storm form in were 19°C, during Tropical Storm Grace of 2009. Grace holds the record for being the farthest northeast forming tropical cyclone in the Atlantic basin. Like 92L, Grace also formed near the Azores Islands, but in early October. The coldest waters I've seen a hurricane form in were 22°C, for Hurricane Epsilon of 2005. Latest guidance from the computer models show 92L meandering to the south of the Azores through Monday, then beginning a slow motion towards the northeast by Tuesday.
Jeff Masters
Reader Comments
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first of all think of they would name it Alberto.
NATIONAL WEATHER SERVICE TALLAHASSEE FL
329 PM EDT SUN MAY 13 2012
FLZ016-017-132000-
LEON FL-GADSDEN FL-
329 PM EDT SUN MAY 13 2012
...A SIGNIFICANT WEATHER ADVISORY IS IN EFFECT FOR GADSDEN AND LEON
COUNTIES...
* UNTIL 400 PM EDT
AT 325 PM EDT...THE NATIONAL WEATHER SERVICE HAS DETECTED STRONG
THUNDERSTORMS 18 MILES SOUTH OF QUINCY...OR NEAR BLOXHAM...MOVING
EAST AT 35 MPH.
THESE STORMS WILL BE NEAR...
TALLAHASSEE BY 400 PM EDT.
WINDS OF 40 TO 50 MPH ARE EXPECTED WITH THESE STORMS.
LAT...LON 3033 8471 3039 8465 3039 8468 3041 8468
3042 8471 3046 8471 3046 8477 3050 8478
3061 8427 3034 8417 3030 8454 3030 8470
TIME...MOT...LOC 1929Z 253DEG 31KT 3034 8462
$$
9-FOURNIER
Some opinions like "TS Alberto will get to 500mph winds!!" arent even likely. That would be something a troll might say.
Pretty sure that's an old image...
Excerpt:
The models exhibited clear differences among
themselves. The CMC is the most aggressive in
forecasting TC genesis. As a result, it had the greatest number of hits, but also the greatest number of false alarms. The NOGAPS was least aggressive, under predicting TC genesis during all seasons.
Experiments with consensus forecasts revealed
that false alarm rates were lower when multiple models
predicted TC genesis. The consensus approach yielded
better results than any one model alone. For example,
when the CMC and GFS both predict the same genesis
event, there is ~75% chance that genesis will occur
(albeit possibly at the wrong time).
6 to 12 hrs sounds like an objective method...anyone can look at a clock and see how much time has elapsed...
But how do you objectively measure "current level of storm activity" Do they count the square miles of orange convective cloud tops in colorized IR imagery? I'd like to know if they do such a thing...that way it can help quench the fire over debates like these...
TS force winds: Yes
Closed LLC: Yes
Banding of convection: Yes
Warm core or hybrid? Yes
Non-Frontal: Yes
Persistent Convection: Somewhat
I don't think I'm missing anything, and I don't get why it isn't named either....
LOL...I do see your point...well taken. Well I am glad you enjoy blogging on here as much as I do...
Increase in coverage, but a decrease in intensity...
The other image HAD to be old. Unless the whole west half of the storm blew off. Convection DOES look very impressive
Persistent convection?
24 hours ago:
18 hours ago:
12 hours ago:
6 hours ago:
Now:
Not persistent enough.
Lol...We can sit here and critique the thing to death, but it is overall in much better shape than it was yesterday.
Notice I said SOMEWHAT.
I'm not criticizing what you said, I'm just saying that it's still too susceptible to little changes in divergence and convergence to be named. If it survives until DMAX I don't see why it wouldn't be named.
It looks like that is an old image...that visible image didn't correpsond to the infrared images being recently posted. I have to concede that we are having a pretty good uptick in convection...which contradicts what I said in my blog post a couple of hours ago. I was saying that the either (a) the northward jog it made yesterday put it over too cool of water temps...or (b) the cold core upper low was warming enough such that we had lost the instability. I guess the cold core upper low is still cold enough for instability after all....
92L's recent uptick was occuring as I was writing the blog post....kinda frustrating....
However...I don't plan to write another update unless the NHC actually names the storm....
The ECMWF is showing why the southwest Atlantic should be watched as well by next weekend. With an upper trough getting trapped off the southeast U.S. coast, development can just as easily take place underneath of it as it can south of it i...n the Caribbean. Both areas may have to be watched. The ECMWF is still quiet on the Caribbean, but the GFS continues to show a storm there. The computers are seeing what we have been talking about, but we're still a week away.
somewhat dos not cut it
it needs too persistent for 6hrs with out t-storms dieing off and it has not persistent for 6hrs too be called a name storm
ZCZC MIATCDAT1 ALL
TTAA00 KNHC DDHHMM
TROPICAL STORM JOSE SPECIAL DISCUSSION NUMBER 1
NWS NATIONAL HURRICANE CENTER MIAMI FL AL112011
800 AM AST SUN AUG 28 2011
THE AREA OF LOW PRESSURE SOUTH OF BERMUDA HAS MAINTAINED ENOUGH
ORGANIZED DEEP CONVECTION TO BE CONSIDERED AS A TROPICAL CYCLONE.
DURING THE LAST 24 HOURS...THE LOW HAS EXPERIENCED SEVERAL BURSTS
OF DEEP CONVECTION...WITH ANOTHER BURST NOW BEGINNING JUST EAST OF
THE CENTER. DVORAK T-NUMBERS HAVE RECENTLY INCREASED TO 2.0 AND
SUPPORT INITIATING ADVISORIES.
This image was posted earlier...but it looks outdated...that true color Aqua image is supposed to look like post 680's visible. Post 680's visible also matches the most recent infrared shown in post 679.
Keep in mind that was August, were talking about a preseason system that is way far off from where Jose was, though I see your point.
You beat me too it!
Of course, deep moisture doesn't mean much if there isn't enough triggering mechanism to fire convection in the first place. Many times Ive seen strong low pressure systems fire impressive complexes of strong thunderstorms under surprisingly stable and relatively dry air masses compared to what it takes good thunderstorms firing here But the point is the atmosphere is plenty favorable enough for heavy convection! There is also a chance of severe, check out these values, this will shift towards us later tonight ahead of the gulf:
PINHOLE
Okay just kidding, however new storm tops are firing on the north side. Hopefully this can continue t wrap around
Also, the 12z GFS has our potential Caribbean system MUCH stronger, and much further north, a Florida landfall now.
92L: Alberto
93L:(East coast low) Beryl
94L:(Caribbean System) Chris
By the end of May... That would be madness. Though i don't see it happening. I think We'll eventually Get Alberto by the end of the month...
I beleive 92L Peaked(as of right now) yesturday, it looked rather impressive, but was harshly affected by the aburpt change in atmospheric conditions and went downhill for awhile there. It's attempting to ramp back up, but if it can't get to a point where it shows Consistency by the end of the night, were not seeing Alberto.
Theres a chance of like a 40/100 for alberto out of any three
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