EPAC and CARIB thoughts

[Anonymous]

The EPAC hurricane season began on May 15 and already there are signs we'll see a TS or even hurricane this week based on the latest model trends and outputs.

UKMET has been showing a potent TC (probable hurricane) in the EPAC for the past 4 days. It started out Thu-Fri showing 1 strong TS/weak hurricane to develop near 10N/100W and track NW a fair distance away from the Mexican coastline. However, it has been slowly shifting the track further east...12Z run now takes it more NNW so that it passes offshore, but still pretty close, to the Mexican coastline...

12Z UKMET 6-Day SLP Animation

The NOGAPS has also been latched on this low for the past few days. It is trending slightly stronger, closer to hurricane strength...and also takes it on a path relatively close to Mexico...

12Z NOGAPS 6-Day SLP/Precip Rate Animation

The EURO also showed a hurricane in the area on Fri and Sat...however today's run suddenly drops it. We'll see if it picks it back up tomorrow or not.

The AVN/GFS has picked up on the low the past few days too but has not shown any development whatsoever.

12Z AVN 6-Dat SLP Animation

Also I want to point out something else you may have noticed in those loops...and may be the problem with AVN. Notice how the UKMET and NOGAPS both also develop a weaker low further west, around 120W. The AVN actually picks this up moreso than the low off Mexico despite having a more favorable environment further east. Could we have 2 EPAC systems? The answer is no...for one the UKMET has been inconsistent with it, and compared to yesterday is much less agressive. The EURO hasn't shown any development in that area period...also development that far west is climatologically uncommon at this time of the year. Therefore it's probably just a phantom low that won't amount to anything at all, and I'm not that concerned with it.

Going back to the low that a lot of the models develop offshore Mexico...the consistency with the models (namely UKMET and NOGAPS) is impressive. ALSO take into account that we saw 2 systems develop in the Indian Ocean a week or so ago...and currently we have 3 TCs (including a supertyphoon) in the WPAC. These bursts of activity are in response to an intense neg MJO in progress...it's next target is indeed the EPAC...so we can expect conditions across the EPAC to be conducive for TC growth in the coming days.

30-Day MJO Frame-by-Frame

Based on the model consistency and MJO...the potential is there that we'll see TS Agatha in the EPAC later this week...possibly cat 1 Hurricane Agatha. If the EURO does not pick it back up tomorrow then we may not be talking about much...but I'd say the chance is is about 50/50 right now. If we do see Agatha, a track offshore Mexico is likely...though if the slight model trends continue, outer rainbands could spread onshore.



Now there's something else I want to bring up...which is more exciting to discuss than the EPAC. Take a look at the loop below...

Carib Sea/W Atl Colorized IR Animation

The convection you see in the SW CARIB that's currently dying down is not anything to get excited about...but is something to watch. As evident in the satellite loop, there's a MLC in that area...but no LLC at the moment. Also clearly noticeable is the strong westerly shear in the vicinity of the system...preventing it from strengthening. Normally, a disturbance like this would not be anything to watch real closely, especially at this time of the year. But surprisingly, quite a few models show a lessening of the shear and in turn show tropical development from this...

UKMET has been showing a weak TC to develop on Day 6 between Jamaica and the DR.

12Z UKMET 6-Day SLP Animation

The AVN/GFS does the same, except develops it much farther west...off Central America.

12Z AVN 6-Day SLP Animation

The CMC (not my favorite tropical model) also picks up on it and shows a pretty potent TC in the same location as AVN by Day 6.

00Z CMC 6-Day SLP Animation

And so does the NOGAPS...very similar to the AVN and CMC...

12Z NOGAPS 6-Day SLP/Precip Rate Animation

Here's the real kicker...the EURO has shown a significant TC in the area the past 2 runs. Yesterday it showed a significant TC from the EPAC and CARIB system. Today, it dropped the EPAC but STILL shows a significant TC passing over Jamaica and then into the Bahamas...

12Z Euro SLP Animation

If this were to develop, it wouldn't be for another 4-5 days at least. Strength wise, none of the models show anything more than a TS...and considering the time of the year that's probably the most we'll see if development does occur. Regarding track...the models are all in agreement on showing a large weakness in the subtropical ridge later in the week. This will pull any TC that may be present off to the NNE...NOT in the Gulf. The chances are pretty small it'd threaten S FL, but that depends on where the LLC (if there ever is one) develops. In weak systems like this, center relocations and multiple centers are to be expected. The AVN, CMC, and NOGAPS develop the LLC further west, whereas the UKMET and EURO have it form more to the east. Further west would of course pose more of a threat to the FL straits. The weakness in the ridge should be sufficient enough to pull it far enough east from FL, but the key will be to watch for any trends.

And I already mentioned the deal with the MJO...so could this come true? Now although the models are in a pretty good agreement as far as development goes today, what's lacking is uniformity in the models. If the majority of them are still showing a TC in the next 2 days like they are today...then the chances will be increased. If they all drop it, then it's toast. We are afterall dealing with something a week away...so the chance for development right now is still SLIM. Nothing to get concerned about this early, especially since it's mid May...just worth watching.



To sum all that up, IMO there's a fair chance we'll see a TS or minimal hurricane in the EPAC late this week and take a track to the NNW offshore Mexico. Then there's also a VERY SMALL chance of a TD or TS in the W CARIB early next week that is pulled to the NNE. Should be an interesting week in the tropics just to see what happens.

[Matthew5]

That was a wonderful discussion

[Derek Ortt]

What in God's earth is that CMC on. Usually is much better than that. I suspect that may not entirely be tropical as it rapidly forms from a broad low over land

[dixiebreeze]

Great informational post Rob

[Anonymous]

What in God's earth is that CMC on. Usually is much better than that. I suspect that may not entirely be tropical as it rapidly forms from a broad low over land

I did notice the low it develops is real broad...almost non-tropical like. I'm not much of a fan of CMC in the first place (I know you probably differ lol)...will be interesting to see if keeps developing a substantial low like that in runs to come.

[Anonymous]

What in God's earth is that CMC on. Usually is much better than that. I suspect that may not entirely be tropical as it rapidly forms from a broad low over land

I did notice the low it develops is real broad...almost non-tropical like. I'm not much of a fan of CMC in the first place (I know you probably differ lol)...will be interesting to see if keeps developing a substantial low like that in runs to come.

Yeah there is no way that the model is predicting a fully tropical system. It is likely too far north and west anyway. The next run should be a bit more interesting.

[Brent]

Very interesting.

[Aquawind]

NWS is watching down here..

.LONG TERM (WED NIGHT-SUN)...SFC RIDGING WILL CONTINUE OVER THE AREA
THRU THE PERIOD. THIS WILL KEEP ATMOSPHERE FAIRLY DRY...ESPECIALLY
FRI THRU SUN...AND ALLOW DAILY SEA BREEZES TO PUSH INLAND WITH
LITTLE SHOWER ACTIVITY FORMING ALONG THE BNDY. ONLY CHANGE DAY TO DAY
WILL BE LOCATION OF AN UPPER LEVEL CLOSED LOW...WHICH IS CURRENTLY A
S/W OVER CENTRAL TX. 00Z GFS HAS IT FURTHER E...OUT OVER THE S
CENTRAL GULF ON THU AND JUST W OF THE KEYS ON FRI...THAN PREVIOUS
RUN. THIS FEATURE WILL INCREASE UPPER LEVEL CLOUD COVER OVER THE
WEEKEND DOWN SOUTH. ALSO...MODEL GUIDANCE IS DEVELOPING A SPURIOUS
TROPICAL LOW OVER THE NW CARIBBEAN. THE EFFECT OF THIS LOW ON
GUIDANCE IS TO INCREASE WINDS OVER THE SRN ZONES. WILL DISCOUNT THIS
EFFECT...BUT CONTINUE TO MONITOR FOR ANY DEVELOPMENT.


schmodels......

[weatherlover427]

WEAK H50 TROUGH/LOW CURRENTLY OVER TX DROPS INTO THE WRN GOMEX AND GETS TRAPPED BENEATH THE EXPANSIVE RIDGE. MAJORITY OF MED RANGE GUIDANCE (GFS/GGEM/ECM/NGP) WANT TO MAINTAIN AND ACTUALLY STRENGTHEN THIS FEATURE...DRIFTING IT SLOWLY EAST TWD THE FL STRAITS/CUBA AND AIDING IN THE SPINUP OF WHAT WOULD BE A HYBRID OR AT THE VERY LEAST A BAROCLINICALLY ENHANCED TROPICAL LOW OVER THE WRN/CTRL CARIBBEAN. PLAYING DEVIL'S ADVOCATE FOR A MINUTE...DEVELOPMENT/ADVERTISED TRACK OF THIS FEATURE WOULD TIGHTEN PGRAD UP QUITE A BIT ALONG THE FL SE COAST TWD DAY 7. THAT HAVING BEEN SAID...AM SKEPTICAL OF THIS TAKING PLACE AS THE H50 GOMEX LOW THAT WAS ADVERTISED A WEEK OR TWO AGO BY THE GFS/ECM NEVER MATERIALIZED...AND IT APPEARS THAN SFC DEVELOPMENT WOULD BE DEPENDENT UPON BAROCLINIC ENHANCEMENT - I.E. STRENGTH OF THE H50 LOW/H25 JETSTRK. WILL GO WITH THE UKMET SOLN...WHICH IS MUCH WEAKER AT H50...AND SHOWS NOTHING AT THE SFC.

------------------------------------------------------------

Melbourne, FL NWS AFD this morning regarding the potential situation.. Just as an FYI to everyone.

[Brent]

The Key West AFD sounds more encouraging.

Anyway... the fact they are even mentioning it a full 2 weeks before the season begins is interesting.

[Anonymous]

Looking at the situation as of today...

We're starting to see more convection blossom across a large portion of the EPAC. What's VERY evident is the large anticyclonic wind pattern in the upper levels across the EPAC...the only area currently exposed to strong shear is west of 110W where a few of the models still try to develop a weak TC. I don't doubt that a low will form there, but shear should keep it from developing into a classified system. It's the convection east of this longitude that stands the most chance. Although we have yet to see the convection bond into one concentrated area...and have a low pressure form...the upper level conditions are definately favorable for slow tropical development over the next few days.

Latest Shear Tendency and Direction

EPAC IR Image

Interestingly (and a bit surprisingly), the UKMET is being quite a bit less aggressive with the EPAC storm. It still shows a TC but not nearly as strong as it did yesterday. As seen in the loop below, the main reason for this is the UKMET is trying to develop 2 systems again...which of course would split the energy and thus 2 weaker systems rather than one stronger one. I'm still not believing this double trouble crud that it's trying to show because of 1)the unfavorable shear west of 110W, 2)other model solutions, and 3)climatology...we are afterall only days into the season.

The AVN, for the first time, shows a substantial storm in the EPAC that develops around 105W and travels NW on a track well away from Mexico. The NOGAPS has stuck to its thinking of one EPAC storm that moves parallel and close to the Mexican coastline. And today's EURO has yet to come out.

In other words, what we have with the EPAC is spotty convection developing under a favorable anticyclonic pattern...and most models developing a TC or 2 in one location or another. So I'm a little more confident that we will indeed see a classified TC in the EPAC later this week...but less confident as to where it will be since models are more diverged on which of the progged multiple lows to develop.



Now for the deal in the Caribbean...

Nothing special or eyebrow raising happening in the SW Carib right now. Like yesterday, just sporadic convection around a weak mid level circulation. In contrast to the EPAC, the area is still suffering from strong westerly shear...which will certainly keep us from having a TC down there anytime soon.

W Carib Colorized IR Animation

Today the models have really converged in both development and track. Yes, the models STILL want to form a weak TC by the end of the upcoming weekend in the Carib. The AVN, CMC, NOGAPS, and UKMET are now in agreement on showing a weak TC forming off the Nicaragua/Honduras coast around Day 5...and then moving it to the NE (taking it close to Jamaica and then towards eastern Cuba and well EAST of FL) as it feels a large weakness in the subtropical ridge. The models still differ slightly in intensity, but after yesterday's split in where the low forms...the track solution is much less spread out.

The shear is very strong in the area right now, but it is expected to slowly retreat in the coming days (as it has done in the EPAC)...allowing for a moderately more favorable environment for something to start brewing in the west Carib. However, we're not talking about a beautiful no-shear pattern...we are afterall still 10-15 days away from the official start of the Atlantic hurricane season. So IF a TC forms in the Caribbean later in the week or early next week, we'll probably be talking about a weak TS at the most...not to mention that a track close to FL is unlikely.



Basically, chances still look good for an adequate TC in the EPAC later this week...and a weak TC in the west Carib can't yet be ruled out towards early next week either.