Maria a Threat to the Northern Lesser Antilles, Puerto Rico, Hispaniola, and the Bahamas

Maria forecast/discussion 2 (update to forecast 1):

Tropical Storm Maria remains highly disorganized, with pulsing convection noted north of the low level circulation on IR Satellite loops and microwave images. Because of the center being displaced from the convection, Maria has weakened some today as I expected last night. Maria is still heading just a tad north of due west, at 275/15, and has gained very little latitude since yesterday.

Track forecast reasoning remains essentially unchanged, although will have to be adjusting slightly south/west due to yesterdays day 1 forecast busting too far to the north. Maria is on the southern periphery of a subtropical ridge over the central Atlantic and will begin over the next 48 hours gradually turning more WNW and then NW with time as ridging to the north of the cyclone weakens over the western Atlantic due to Lee’s remnants over the OH/TN Valleys and due to the upper level westerlies being farther south than normal over the western Atlantic due to a positive NAO.

However, given Maria will remain weak in the short term and given the cyclone has tracked farther left than anticipated in the near term, a track close to or over Puerto Rico and near but likely still north of Hispaniola will be forecast, which is farther south than yesterday’s forecast. In addition, a track much closer to the central Bahama’s will be shown. The GFS and its ensembles show Maria tracking north and being picked up by troughing associated with Lee’s remnants before they pull out causing the system to recurve well off the US east coast. However, the ECM and its ensembles slow Maria down in the mid range and narrowly allow Maria to escape before troughing pulls out of the eastern US. While landfall is still not likely in my opinion, the 12z Euro ensembles show troughing along the east coast at day 6, in association with a (brief) -NAO/+PNA. However, the ensembles allow a strong Pacific jet to weaken the western US ridging after this, and show the pattern becoming much more zonal over the eastern US. Should Maria slow down more than expected this weekend into early next week, it is an outside possibility that Maria gets caught up in weak steering currents off the southeast coast. However, this would require Maria to significantly slow down which appears unlikely given there is a fairly fast flow surrounding the ridge that is steering it, and would also require ridging to build back in over the eastern US days 7-10. While both are possible, it is unlikely both will happen at the right times to bring Maria much farther west (into the southeastern US).

As for intensity, moderate shear and dry air are still causing problems for Maria, with convection exhibiting a pulsing pattern. The convection is also displaced from the center of circulation. These problems are expected to continue plegging the tropical storm over the next couple of days. With some decent low level ridging north of Maria, the steep pressure gradient produced may help to continue generating some TS force winds on the northern side of the circulation, assuming some convection continues to fire. So, will maintain Maria as a minimal TS for the next 48 hours. Thereafter, the global models attempt to weaken the shear over Maria and the GFS, CMC, and NOGAPS attempt to develop an upper level anti-cyclone over Maria, just as the system also begins to slow some. All of these global models and the vast majority of the hurricane models show some intensification starting about 48 hours out. The 12z Euro was not so optimistic. The GFS, CMC, NOGAPS and about 2/3rds of the ATCF guidance suggest a cyclone nearing or exceeding hurricane stregnth by day 5. Given that at the upper levels the Euro looks favorable once Maria approaches the Bahamas, will bring Maria up to a minimal hurricane by day 5, despite the ECM not showing much intensification.

Forecast track/intensity:

Initial (0z Friday)…13.2N, 53.6W…35 knots, TS
24 hours (18z Friday)…13.5N, 59W…35 knots, TS
48 hours (18z Saturday)…16N, 65W…35 knots, TS
72 hours (18z Sunday)…19N, 69W…45 knots, TS
96 hours (18z Monday)…22.2N, 72.7W…55 knots, TS
120 hours (18z Tuesday)…25.1N, 76W…65 knots, Cat 1

Posted in Uncategorized | Leave a comment

Nate a Threat to Tampico, MX

Tropical Storm Nate Forecast/discussion 1:

Tropical storm Nate’s satellite appearance has only changed slightly since this morning, with the appearance of a sheared tropical cyclone evident with the center nearly exposed on the northeast edge of an area of deep convection. A recent microwave pass and air-force recon confirm this, with the center clearly displaced from the somewhat banded convection to the southwest of the center. Nate is nearly stationary at this time.

Nate’s track forecast is interesting. At the moment,ridging is in place to the north and to the east of the cyclone, allowing for very little movement. The current motion estimate from the NHC advisory is a SSE drift at about 2 knots. Over the next couple of days, most models attempt to drift the upper low associated with Lee’s remnants farther south into the Ohio/Tennessee Valleys, weakening ridging to the north of Nate. However, ridging should remain in place over the Caribbean to the east of the storm, allowing for a slight increase in forward motion, generally to the north, in the near term.

How far north Nate can get in the near term will be key, as the troughing from Lee’s remnants will only get as far south as the central Gulf of Mexico. For example, the 12z GFS has Nate moving north tonight at a few knots faster than the ECM, and in a few days has Nate far enough north that ridging cannot build back to the north as quickly when Lee’s remnants fill and move east, which would allow Nate to get north into the central Gulf and possibly threaten the northern Gulf coast as the GFS shows. However, the ECM does not bring Nate as far north nearly as quickly in the near term, and in the end begins to lift the trough over the southern/eastern US before Nate can get caught in the accelerated flow on the southern edge of the trough. This allows ridging to build back in north of Nate, allowing the cyclone to turn to the west and make landfall near Tampico Mexico in about 72 hours. Out of the 12z guidance, the CMC, NOGAPS, UKMET and ECM ensembles all agreed with this scenario. The GEFS mean was not as far north as the op GFS, but did not bring Nate inland as far south or as fast as the aforementioned guidance. ATCF track guidance agrees with this track forecast fairly well, however many models are slower than all of the globals (excluding the GFS), however many of these same ATCF models are GFS based. Given this, will ride the 12z ECM/ECM ensembles hard for this forecast, and will give the GFS and GFS based models little weight. Will show landfall near Tampico Monday morning.

As for the intensity forecast, Nate is currently dealing with some northeasterly shear. However, an upper level anti-cyclone is forecasted to build over the storm over the next 12-24 hours, causing the shear that is already decreasing to become favorable for further development. The 12z GFS and ECM models both showed Nate deepening steadily from Friday morning through Sunday. Nate is over fairly warm sea surface temperatures and will move overfairly high heat content waters over the next couple of days. While there is some pretty dry air to the northwest of Nate, it should become less of a problem as shear relaxes. Given this, will show steady intensification through landfall. Will follow the ATCF guidance closely (a tad stronger than the middle of the road), as most models show steady intensification through landfall. Nate still has to become vertically aligned and work out some dry air before it can explosively develop, so will not show rapid intensification in the forecast.

Forecast track/intensity:

Initial…19.7N, 92.3W…60 knots, TS
24 hours (18z Friday)…20.2N, 92.3W…70 knots, Cat 1
48 hours (18z Saturday)…21.7N, 93.8W…80 knots, Cat 1
72 hours (18z Sunday)…22.1N, 95.7W…90 knots, Cat 2
96 hours (18z Monday)…22.0N, 97.9W…85 knots, Cat 2…Inland.

Posted in Uncategorized | Leave a comment

Tropical Wave in the Caribbean…A Candidate for Gulf of Mexico Development?

A large monsoonal trough over the northern Caribbean is
drifting towards the Gulf of Mexico. Global models are all suggesting future
development, and the National Hurricane Center has flagged this area of
disturbed weather with a 10% chance of developing into a tropical cyclone
through Thursday evening.

Currently the trough is under a good amount of northeasterly
shear. This is expected to continue in the short term. However, a small upper
level anti-cyclone is located to the north of the system, which is aiding in
providing lift over the southern Gulf and northern Caribbean, which should
allow this trough to continue to fire some convection over the coming days as
it drifts towards the northeast.

As you can see by the dark colors over the northern and western
Gulf on the image above however, there is a good amount of dry air ahead of
this tropical wave. Given the severe drought over Texas and high pressure
expected to remain in place over the southern US, this may be an issue to
contend with down the road.

Currently, the tropical wave/trough is associated with a
weak area of vorticity, or spin in the atmosphere. This shows that there is
currently no attempt at a defined surface circulation forming, and this should
not occur in the near term as the system hangs around near the Yucatan Peninsula
of Mexico.

As the system moves into the Gulf of Mexico however, it will
become better situated under the aforementioned upper level anti-cyclone. This
will promote continued convection as mentioned above and will allow convection
to become better organized and concentrated. This will allow the system to
attempt to organize over the western Gulf of Mexico late this week into the
Holliday Weekend.

Right now all of the global models (GFS, UKMET, NOGAPS, CMC,
ECM) attempt to develop some sort of a tropical cyclone out of this system over
the western Gulf as it drifts around. Given warm sea surface temperatures and
what appears to be at least a marginal if not decent environment for further
development once this tropical wave gets into the Gulf of Mexico by some point
Thursday, this seems reasonable and this might be the next tropical cyclone
threat close to home.

As an example, the 12z European model (ECMWF) develops a
large area of low pressure over the western Gulf this weekend and shows it
hanging around for a few days. The large, broad wind field is not atypical with
systems that try to spin up from large, broad troughs of low pressure such as
this system.

What is interesting is that most models develop at least a
sliver of ridging to the north, east, and west of this area of disturbed
weather once it moves into the western Gulf. This supports the weird drift to
the south or southwest over the western Gulf most models show at this time.

Given uncertainty about the future intensity of this system
and where it will exactly spin up given the large gere that would spawn any
future system, it is too early to say for sure where this will go. The upper
level environment and warm SSTs may support a moderately strong cyclone down
the road, but the system’s likely large size and proximity to land and dry air are
possible hindrances to an intense cyclone, so the intensity forecast at this
point would be highly uncertain. But a slow moving possibly tropical system
looks like a decent bet over the western Gulf by the weekend.

Based on heightened chances of a tropical cyclone near the
region, I have placed the Gulf coast from New Orleans south/west through
eastern mainland Mexico into “low risk” area for impacts from this system, the
second from bottom risk level on a scale that goes from minimal, to low, to
medium, to high, to extreme risks. A low risk on my personal, unofficial and
experimental Tropical Cyclone Risk Assessment Scale indicates that adverse
weather caused by a tropical cyclone is possible within the next 5 days.

Disclaimer: All tropical cyclone forecasts and discussions
found on this blog are the personal opinion of Jim Sullivan and Jim Sullivan
only. Jim Sullivan is not yet a degreed meteorologist and is not liable for
personal damages resulting from decisions made due to reading this blog. This
blog is for entertainment purposes and is meant to illustrate what goes behind
tropical cyclone forecasting and to foster discussion, and is NOT intended to
be used for life or death decisions. For official information/forecasts, visit
your local National Weather Service Office webpage or National Hurricane Center
webpage through Listen to all evacuations/advice that comes from
emergency management or local officials.

Posted in Uncategorized | Leave a comment

TD 12…The Next Storm to Watch

Just a couple of thoughts on TD 12…

Given the generally well agreed on large scale pattern shownon models in a week to 10 days, TD 12/Katia needs to gain as little latitude as possible before getting to 65-70W.

The PNA, which was positive while Irene was making a run at the east coast and contributed to shortwaves amplifying west of the east coast given short wave lengths, is expected to become neutral if not negative per the NAEFS during the coming days and is currently modeled to remain in that state through day 14, at least. While there is a chance this changes in the coming days, the GFS/ECM ensembles are both in relatively good agreement in heights becoming higher than normal over the western Aleutians, forcing a trough off the west coast that shifts ridging east well into the western CONUS/Canada. This in turn forces below normal heights near the east coast, as opposed to Irene when the ridging was along the west coast and forced shortwaves to amplify over the Great Lakes given the short late summer wavelengths.

The GFS, and ECM ensembles both reflect this well at D10:

12z Euro ensembles:

12z GFS ensembles:

In addition, there will not be higher than normal heights over the Davis Strait/Greenland to force a sharper trough over the eastern US/Great Lakes which would potentially draw a hurricane farther west if in place (like with Irene).

This all may change, but the ensembles are both in pretty strong agreement on these main upper level features at this time.

Given this, I believe the chances of recurve—likely between the US east coast and Bermuda given likely troughing along the east coast—are at around 85% if this system passes north of 25N, 70W. It’s not necessarily the normal benchmark (20N, 60W) but I believe it works better in this situation given where it looks like the troughing may be located and how amplified it might be in the 1-2 week timeframe. The other 15% would be something unforeseen like an unexpected weakening of the trough or a much weaker system.

Now, working backwards, what are the odds this system doesn’t gain too much latitude in the short term?

TD 12 is currently at a low latitude, south of 10N. However, there is a weakness in ridging between 40-50W that the system is approaching. This should result in a WNW over the next couple days as TD-12 approaches this weakness.

However, the global models agree on weakening this weakness and strengthening ridging over the subtropical Atlantic north of TD 12 over the next couple of days, and by day 4 the 12z Euro showed solid ridging to almost 70W. This should result in a continued WNW motion. However, note how the heart of the ridging is located to the east of the cyclone per the ECM.

This general trend is modeled to continue. The ridging will attempt to build west, however troughing will remain along the east coast with shortwaves continuing to move east (as discussed above) which will keep the western Atlantic ridging noticeably weaker than the eastern Atlantic ridging. This should continue to allow TD 12 to continue gaining latitude for the forseeable future. I’m by no means expecting an early recurve, however given what will likely be a strong system within a few days and weaker ridging over the west Atlantic, it will be hard for TD 12 to be far enough south when it gets to 60-70W to avoid being recurved by likely troughing along the east coast. A track between the goal posts seems to be a good first guess. 

Posted in Uncategorized | Leave a comment

Hurricane Irene Forecast #2

As of mid-Monday afternoon—Irene is developing an inner core as it transverses the small gap between the Puerto Rico and northern Hispaniola coastlines. Irene is also exhibiting excellent outflow, especially on the northern half of the storm which is likely contributing—along with rather warm sea surface temperatures—to the continual firing of deep convection.

Radar out of Puerto Rico indicates that Irene at the very least has an open eyewall, with deep convection around mainly the western side of the circulation. An eye has occasionally tried popping out on visible imagery but currently there are no signs of an eye on IR imagery and no microwave images to clarify the structure of Irene’s inner core. However, over the past few hours the half eyewall visible on radar has tightened some which may be indicative of some strengthening of Irene.

Irene has been and is expected to remain under an upper level anti-cyclone. This is in tandem with an upper low well east of Irene providing for the excellent outflow noted on satellite imagery. There is some dry air in the vicinity of the hurricane, with arc clouds once in a while emitting out of the core, however this does not appear to be having a major impact on the inner core of Irene which is continuing to fire consistent deep convection.

Over the coming days global models generally agree on Irene remaining right under or very near the upper level anti-cyclone that is above it now. This will continue to provide for outstanding outflow/ventilation, which will promote continued deep convection within the inner core of the hurricane whenever the system is over water, which should be a good part of its remaining life. Water temperatures are very warm in the path of Irene and the warmth is somewhat deep over the far southwestern Atlantic, which along with good upper level divergence and low vertical wind shear may result in significant intensification:

The question becomes at what point does the intensification stop, and how strong is Irene when this occurs?

The global models (GFS used as an example) generally show Irene remaining under the upper level anti-cyclone until it gets to near the latitude of the Carolinas. North of here, Irene will begin to interact with the westerlies (which may briefly provide for a burst of intensification as they vastly improve upper level lift over the cyclone as it approaches them). However, up until the latitude of the Carolinas upper level wind shear should remain fairly light and Irene should be able to maintain good outflow, with the westerlies beginning to add to the upper level divergence in the vicinity of Irene as it approaches the Carolinas.

As Irene nears the US coastline continental dry air will become a possible issue. Shear may remain low enough from the Carolinas points south that significant dry air entrainment does not occur; however the 12z GFS (shown above) along with the 0z ECM indicate continental dry air edging right up to Irene’s moisture field, which may cause some disruptions within the inner core as Irene gets near the US mainland.

While Irene will move over very warm sea surface temperatures even up to the Carolina coast, the depth of the warm water becomes much shallower as one moves north of the Bahamas (shown above) which may also result in some decrease in instability available for Irene if her forward motion is slow enough off the southeast US coast.

So essentially, will forecast a steady state or slight weakening days 4-5 as Irene nears the coast, however based on outstanding upper level conditions and only minor issues otherwise I do not believe Irene will significantly fall apart upon landfall (assuming the system does make a landfall).

Irene will interact with Hispaniola over the next 24 or so hours, but then will have at least 3-4 days before possible interacting with the southeastern US. Irene as mentioned will be in a very favorable environment for intensification above sufficiently high TCHP waters to support a very strong cyclone. So at the very least will need to ramp up Irene to minimal category 3 status within 72 hours, with some rapid intensification being possible between 24-96 hours out given the very warm sea surface temperatures the hurricane will be transversing  and the outstanding upper level pattern the hurricane should be under. Most models peak Irene somewhere between 72-96 hours out as a strong Cat 2 or low end Cat 3. Will peak at around 110 knots between hours 72-96, and will have to watch carefully for periods of rapid intensification. Will bring down to 105 knots by day 5 to reflect the slightly more hostile (but still relatively good) environment around Irene as discussed above.

A weakness in ridging has opened up north of Irene due to a trough moving off the US east coast. Initially this was thought to possibly not have a significant impact on Irene’s motion due to Irene being a good bit farther south, however center relocations and a deeper cyclone have allowed Irene to end up farther north than thought just 24-48 hours ago. Irene should continue to move WNW in the near term on the southwestern periphery of subtropical ridging centered to the east of the cyclone.

As the trough currently along the east coast lifts to the northeast, it will leave a small weakness in the ridging over the southeastern US. With good ridging still extending just about to the Carolina coastline and Irene being on the southwest side of it, a general WNW motion should continue for the next couple of days, taking it right into the Bahamas.

The next trough will move through on the rather zonal flow Thursday-Friday. How fast this trough moves through and how much it digs will likely determine if Irene makes a direct impact on the US southeast coast or not.

There are two main factors that will determine how much this trough digs:

  1. –NAO ridging over Greenland and the Davis strait.
  2. The +PNA troughing over the Aluetians/Alaska.

The NAO and PNA have generally been modeled to weaken some by the end of the week into the weekend. Since both the –NAO and +PNA support troughs along the east coast, the stronger these teleconnections are the more the trough digs along the east coast.

As you can see above, the 12z ECM does show the –NAO weakening noticeably and the +PNA remaining about the same. The ensemble NAO forecasts have come into slightly better consensus on the NAO bouncing back towards neutral by mid-week, which is crucial to where Irene tracks:

The GFS ensembles are in fairly good agreement in moving the first trough out relatively quickly and clearly leave Irene behind off the southeast coast:

The next trough comes through the flow roughly 36 hours later (Saturday night) and will most likely be the trough that accelerates Irene to the N and then NE.

At this point most global models have Irene just off the southeast coast, which would make escaping without landfall difficult. Out of the 12z model suite the Euro remained most consistent and indicated a landfall near the SC/NC boarder. The CMC/GFS indicated a brush/possible direct hit on the outer banks. The NOGAPS indicated a likely NC landfall and the UKMET remains well left of all guidance and brings Irene north along the Florida coast and into either Georgia or SC. The 12z GFS ensemble mean appeared to be in agreement with the op GFS/CMC. The 0z Ensemble mean appeared to indicate a landfall somewhere near the NC/SC boarder, but the spread out pressure fields indicated that some members had landfall in Georgia and some missed the outer banks to the east.

Given the above information and likelihood  of the trough on Friday leaving Irene behind off the southeast coast, will forecast a landfall near the NC/SC boarder and will continue moving Irene NE just off the Mid Atlantic coastline.

Track forecast (black dots are on a 24 hour interval from 18z Monday):

Intensity forecast:

Initial (18z Monday): 70 knots/Cat 1

12 hours (6z Tuesday): 75 knots/Cat 1

24 hours (18z Tuesday): 80 knots/Cat 1

36 hours (6z Wednesday): 85 knots/Cat 2

48 hours (18z Wednesday): 95 knots/Cat 2

72 hours (18z Thursday): 105 knots/Cat 3

96 hours (18z Friday): 110 knots/Cat 3

120 hours (18z Saturday): 105 knots/Cat 3

Posted in Uncategorized | Leave a comment

To all the Accu Forum posters

I no longer post on that site due to a disagreement with the administrator as to what is crossing a line and what is not in relation to a joke with the moderators.

Unless you have an account on, this is the page to look at if you want to see my write-ups, which I have wrote primarily for you over the years.

Posted in Uncategorized | Leave a comment

Tropical Storm Irene

Tropical Storm Irene Forecast/Discussion:

As of late Saturday evening, newly formed tropical storm Irene is producing a fairly large but disorganized area of deep convection, with a small but potent surface circulation located under the southwestern edge of this convection. Irene is exhibiting good outflow as well and is moving towards the WNW.

As Irene continues moving WNW over the coming couple of days, both the GFS/ECM showing the upper level anti-cyclone moving with the cyclone towards the WNW and continuing to provide low shear and favorable outflow for intensification of Irene over warm waters. Dry air also appears to be a minimal issue, especially given the broad nature of Irene’s moisture field. In addition, low level winds are rather light over the eastern Caribbean, for a change, and will be while Irene transverses the area:

This means that Irene will have until Monday morning to align its centers in a low shear environment. If that occurs Irene may well become a hurricane over warm waters with good outflow before interacting with land, and could end the Atlantic Basin futility streak at 8.

While Irene’s intensity starting Monday will be highly dependant on how much land the system runs into, the upper level anti-cyclone will remain over the cyclone as it continues trekking NWward in the general direction of the SE US. Combined with warm waters, the combination of rather weak shear and good outflow may provide for an intensifying Irene when she is over water.

There are some indications that Irene may miss the bulk of Hispaniola to the south (see track reasoning below) and will track over eastern Cuba. This will have an impact on intensity but likely won’t gut a large but well defined system, meaning Irene may still be potent north of Cuba.

In the near term, Irene will continue to follow the low level easterlies on the southern periphery of a subtropical ridge between Bermuda and the Azores. The cyclone will begin to approach a weakness in ridging located along the longitude of the eastern US seaboard. This will mean a generally WNW motion over the next couple of days, but a gradual right turn thereafter as Irene begins to deepen some and follow the deeper steering currents, and as Irene moves towards the weakness in the ridging.

There are two tough aspects to the track forecast which are dependant on the timing/strength of a shortwave moving over the eastern US around day 4-5.

  1. Does Irene completely miss Hispaniola to the south or move over part of the Island?
  2. Once Irene clears Cuba, will the trough to the north come in late enough that she doesn’t turn due north until she is east of Florida, over Florida, or west of Florida?

Given fairly strong ridging with no significant weaknesses north of Irene west towards the Bahamas and no troughs expected to move off the east coast until Irene is at the longitude of Hispaniola, I believe there will be no significant northward turn in Irene’s motion will occur until the system is past Hispaniola and that Irene will move over southern Hispaniola. Most global models agree with this scenario. Some models kept Irene just south of Hispaniola in their 12z runs, however an extrapolation of the current motion brings Irene over Hispaniola. And while I expect no major northern turn with Irene before Hispaniola, I expect no southern turn either.

Note how the 12z GFS (above) does not show a weakness opening up in ridging north of Irene until it is just passing the westernmost tip of Hispaniola.

Out of the 12z model suites, only the operational ECM was east or along the east coast of Florida. The GFS was along the western coast of the state, with strong signals from the ensembles of both models of Irene getting clearly into the eastern Gulf of Mexico by the end of the upcoming week. The CMC is also clearly into the Gulf of Mexico on its 12z run.

So the question becomes, how plausible is the idea of Irene getting west into the Gulf?

Over the next 5 days through midweek, the pattern will resemble a fast moving subtropical jet-stream over the northern CONUS with a large and persistent upper low over Alaska with shortwaves breaking off and zipping east in the flow. There will also be a weakly negative NAO in place with higher heights than normal over the Davis Strait. This will result in higher than normal heights over the western US with a large ridge of high pressure in place with below normal heights along the US east coast, with a slight weakness in ridging.

By late next week into next weekend, the ECM Ensemble means hint at the pattern changing, with the upper level low over Alaska weakening significantly, along with the negative NAO. This will mean the ridging may attempt to build back towards the eastern US (ignore the area of lower heights over the northern Gulf and SE due to the ECM ensemble’s interpretation of Irene), which would force a farther south/west track of Irene should one of the shortwaves that comes through before the end of the week not completely pick up Irene and recurve it.

Given Irene will still be in the Caribbean, the trough that moves off the east coast Tuesday will NOT be enough to completely pick up Irene. It will however open a weakness in the ridging north of Irene, causing the system to slow and gradually turn more to the NW.

The next shortwave in the flow will move north of Irene somewhere around Thursday. At this point Irene will likely be north of Cuba. Right now, given the rather weak nature of the –NAO (somewhat zonal flow) it does not appear this shortwave will carve out a particularly strong trough over the eastern US, meaning the will it may turn Irene slightly more to the right, a turn to the due north or NNE may not be likely. In addition, the westerlies will remain well north of the system as this shortwave passes, meaning wherever Irene goes near the end of the week it will do so slowly.

After the shortwave moves out, some models (most notably the ECM Ensemble mean) attempt to build ridging back in north of Irene which would most certainly force the cyclone into the eastern Gulf.

There is also the chance the shortwave slows down some due to the weakening –NAO and that this ridging does not rebuild north of Irene.

Given the uncertainty, will not try to be too fine and will forecast a track for days 6-7 over far western Florida. Intensity will be highly dependant upon whether or not the system makes it into the Gulf.

Track forecast (through day 7) and intensity forecast (through day 5):

12 hours/8am EDT Sunday: 50 knots (TS)

24 hours/8pm EDT Sunday: 60 knots (TS)

36 hours/8am EDT Monday: 65 knots (Cat 1)

48 hours/8pm EDT Monday: 70 knots (Cat 1)

72 hours/8pm EDT Tuesday: 55 knots (TS)

96 hours/8pm EDT Wednesday: 45 knots (TS)

120 hours/8pm EDT Thursday: 60 knots (TS)

Posted in Uncategorized | 2 Comments