Texas/New Mexico/Louisiana/Mexico Obs And Discussion Thread Part 4

[Srain]

The overnight guidance is suggesting a return to a wet pattern as we head toward the late weekend/early next week timeframe as the ridge that has been anchored across the Red River Valley retreats N and W and another weakness develops over Central/SE Texas/Louisiana. The fly in the ointment is a developing Kelvin Wave forecast to shift E from the EPAC at the same time. Then add to the mix a potential tropical system nearing the Yucatan and we have recipe for yet another heavy rainfall event. While it is too soon to know the finer details, it does appear that the hot and dry weather we are currently experiencing may well become a distant memory as rainfall once again returns and all eyes turn to the tropics. Stay Tuned!

[Srain]

Morning e-mail from Jeff:

Atlantic basin tropical activity appears to be entering into a more active period over the next several week.

As is normal for this time of year, the Atlantic basin tropical activity usually shows an upswing in activity starting in early August. Factors over the Atlantic basin do suggest that the potential for tropical cyclone formation will be increasing over the next several weeks in part due to climatology and in part due to increasingly favorable atmospheric factors within the basin. Tropical waves leaving Africa are slightly more well defined and robust, stable and dry African air moving westward off Africa is slowly subsiding, a fairly favorable MJO pulse will be moving into the basin over the next 2 weeks. Forecast models are resolving these increasingly favorable factors with increasing tropical activity. However one must remember that we are borderline ENSO warm (El Nino) in the Pacific and this can negate development in the Atlantic basin with increased wind shear even when all other factors are favorable.

99L:

A weak surface low pressure system located 1100 miles WSW of the Cape Verde Islands in remains embedded within the monsoon tropical across the central Atlantic basin. A review of water vapor images and Total PW images show a large envelop of deep tropical moisture with this feature and the surface trough protecting the surface low with dry air well to the north. Convection is overall disorganized and scattered near the feature and not centered or concentrated near the weak surface low, but off it its north and northwest. As is usual with systems tangled with the monsoon trough, slow development is possible, but the key word is slow!

Global forecast model support for this system is fairly good with nearly every model making it into a closed storm (exception the NOGAPS model which keeps it an open wave). Most of the guidance shows fairly quick development east of the Windward Islands, except the EURO which races the system westward barely keeping it a defined system. Nearly all of the guidance shows the system struggling after making it near/into the Caribbean and this is likely a factor of increased wind shear (either due to a possible fast forward motion or increasing upper level winds aloft). Feel the EURO is too fast on the westward motion and the CMC too far to the north and too strong. The system will likely continue a W to even WSW track for the next 2-3 days and gradually organize possibly into a tropical depression or even a tropical storm as it nears/approaches the Windward and Leeward Islands. After that there is much spread in the track and intensity guidance.

Does a Wet July suggest an increased threat of Texas tropical activity in August and September?

Chris Hebert of Impact Weather recently completed a study looking at the effects of the top 20 wettest and top 20 driest July’s and the impacts of tropical activity on the upper TX coast in August-November of that year. The results are seen in the graphic below and are fairly dramatic. For the 20 wettest July’s, 13 tropical storms impacted the NW Gulf following that wet July versus 9 in the top 20 dry years. Even more astounding is that 11 hurricanes impacted following a wet July with only 4 in the dry years and 8 major hurricanes impacted the NW Gulf versus none following a dry July. To sum up the data following a wet July, there is a greater than 50% chance a hurricane will strike the TX/LA coast.

The reasoning of this makes sense, as a wet July strongly indicates a lack of strong high pressure over TX (much like this summer) usually with a weakness or trough in the height field aloft in this region. Tropical systems approaching from the south and east will flow toward this weakness in the ridge…hence unlike in 2011 when Texas was strongly protected by strong high pressure, this year we are not and we will need to keep a very close eye on developments over the next 2 months.

[Chinook]

Amarillo AFD: "WEDNESDAY THROUGH THURSDAY... WED AND THU SHOULD BE THE 2 HOTTEST DAYS OF THE WEEK FOR MOST AS H85 TEMPS CLIMB TO NEAR OR ABOVE 35C IN SOME PLACES. HIGHS COULD SURPASS 110F IN FAR ERN ZONES EITHER OR BOTH DAYS...WITH ALL TIME RECORDS IN JEOPARDY."

Norman AFD: "GIVEN THIS AND THE LACK OF ANY MENTIONABLE PRECIP...WIDESPREAD 105 TO 110 DEGREE TEMPERATURES ARE EXPECTED THROUGH LATE WEEK AND A FEW AREAS MAY EXCEED 110 DEGREES ON WEDNESDAY AND THURSDAY."

[Srain]

Afternoon e-mail from Jeff re: Comparing July 2011 to July 2012:

All,

I have compared the rainfall cross Harris County for July 2011 and July 2012 and the results are very impressive (showing how dry 2011 was and how wet 2012 has been).

Over the northwest part of the county, where rainfall was least last July it has been the greatest this July. Most locations across Harris County are running over 5 times the amount of rainfall this July compared to last July and across the NW part of the county the rainfall this July is 10-15 times more. For a dramatic comparison site 1190 (Little Mound Creek at Mathis Road:July 2011: .04 in compared to July 2012: 17.52 in)

I have also attached all the Flood Warning gage stations for July 2012 and July 2011 rainfall at each site and the differences along with a graph showing the difference. I also attached the January to July rainfall and those differences.

July 2012 Rainfall:

July 2011 Rainfall:

[Srain]

The overnight operational guidance continues to advertise a developing inverted trough over Louisiana/E Texas as we head into early next week. The fly in the ointment continues to be what will become of 99L and if that disturbance tracks W into the Western Basin. The PW’s look to increase to the 2+ range as well and with low convective temps and no capping issues, heavy rainfall where storms develop may become an issue as deep tropical moisture streams inland.

[Ed Lizard]

Reading main forums, looking at global and tropical specific models:

99L has a reasonable chance (red risk per NHC) of becoming a TD or TS Ernesto before the islands. The Caribbean will not be its friend, and it will probably die. Even the Western Caribbean may not be its friend.

So, my take, it probably doesn't make it to the BoC/Gulf, but if it does, could have Northern Mexico or Southern Texas as a target, and Dolly 2008 rained on my lawn. Even if it does, if there is an inverted trough over the Western Gulf, enhanced moisture could be drawn as far North as my lawn.

Maybe. Ensemble imagery 500 mb heights might suggest most of the effects of 99L, whether developed or not, might stay South. But 6Z GFS 1000 mb spaghetti says it wasn't over when the Germans bombed Pearl Harbor, as far as rain. Fine line there, cancelled work, strong TS, minimal Cat 1, good, any stronger, mad rush for batteries, boarding windows, AC out in August, relative's Jamaica Beach playa party pad, bad.

[Srain]

Morning e-mail from Jeff:

Tropical wave/weak surface low located 1000 miles east of the Windward Islands this morning and moving westward at 10-15mph. Overnight the organization of this system has remained nearly the same if not weakening some. There is scattered deep convection near/surrounding the weak surface low, but not concentrated convection. The NHC has increased the potential for tropical cyclone formation from this wave to 60% in the next 48 hours, but development will be slow.

The wave is tracking westward under the influence of deep layer ridging over the central Atlantic Ocean. A large mass of dry air and African dust is noted in visible images north of 99L and some of this dry air may on occasion become entrained into the system limiting convection. Strong wind shear is also noted just north of 99L, but its current position is fairly favorable. With favorable water temperatures, light wind shear and decent moisture the system is expected to gradually develop into a tropical cyclone.

Global forecast models show development of this feature in the short term, but indicate little development and possible weakening of the system in the Caribbean Sea as upper level conditions become hostile. None of the guidance is overly aggressive with this system, and while it may at some point in the next 72 hours make tropical storm status, it will likely struggle on a track through the eastern and central Caribbean Sea. If it survives, it may find more favorable conditions in the western Caribbean Sea toward the start of next week.

Models are in good agreement with the system reaching the Windward Islands in the 48-60 hour time period or late Friday and then continuing its W to WNW track toward the western Caribbean Sea by the early part of next week. It is very possible that any tropical storm approaching/passing through the Windward Islands may then weaken back into a strong open wave over the central Caribbean Sea.

Forecast Model Tracks:

[Ed Lizard]

The European Community model would clearly be ideal for my lawn.

[Srain]

The 12Z suite continues to advertise a weakness/inverted trough developing as we head into next week. The worrisome issue is that the latest guidance brings a Tropical Depression or TS Ernesto into the Yucatan near the same time adding to the available deep tropical moisture surging into the Western Gulf.

[Srain]

E-mail from Jeff:

Tropical wave east of the Windward Islands has been upgraded to Tropical Depression # 5 this afternoon.

Tropical Storm Watches issued for the Windward and southern Leeward Islands.

Discussion:

The organization of the feature has increased enough to be declared a tropical depression with deep convection continuing to develop near/over the low level center and fair outflow. #5 is moving WNW at 18mph and this direction and speed is expected to continue for the next 3-5 days. On this track the system will be moving across the Windward and southern Leeward Islands late Friday and a tropical storm watch has been issued.

Track:

TD # 5 is embedded within a deep layer ESE to E flow on the south side of a large sub-tropical high over the middle Atlantic. There will be little change in the forecast reasoning for the next 72 hours with the system moving generally W to WNW at 15-20mph. This will quickly take the system across the Windward Islands and into the central Caribbean Sea this weekend and into the western Caribbean Sea by early next week. By early next week, models begins to diverge on the handling of the weakness along the US Gulf coast and the retreating of the ridge over the southern plains to the SW US and the building of the sub-tropical ridge over the SW Atlantic. Feel that there is good confidence in the track through 72-96 hours and then once in the western Caribbean Sea we will have to see how much ridging remains north of the system and how much if any of a NW turn develops toward the day 5 period.

Intensity:

Conditions are overall fairly favorable for intensification with warm ocean waters below and only modest amounts of wind shear and dry air. Expect slow intensification in the short term…likely to TS intensity on Thursday…as the system develops and consolidates. Once in the Caribbean Sea, the GFS shows fairly favorable conditions (really favorable over the western Caribbean) and its SHIPS intensity guidance makes the system a hurricane. The EURO has trouble keeping the system a closed tropical cyclone, but the latest run of the EURO has come in stronger suggesting the GFS may be on the right track. The current NHC forecast will follow the GFS guidance and makes TD # 5 a hurricane in 5 days near Jamaica. The two hurricane forecasting models are also at odds with the GFDL opening the system into a wave and the HWRF making is a tiny hurricane near Jamaica. At this point I put little faith in the intensity guidance beyond 48 hours, but have seen a many a good looking wave/TD/TS pass into the Caribbean and fight unfavorable upper air winds and restricted air flow from South America.

[Ed Lizard]

Steve posted the EXPERIMENTAL FIM on the local KHOU-TV 11 forum. KHOU stands for Houston.

[Srain]

The 06Z Hurricane Models (HWRF & GFDL) are in general agreement of a strengthening system once it nears the NW Caribbean. Both of those models suggest a WNW track across the Caribbean before turn a tad more NW as it passes below Cuba nearing the Yucatan Channel in about 126 hours...

[Srain]

Morning e-mail from Jeff:

Disorganized tropical system heading for the Windward Islands.

Discussion:

Poorly organized TD # 5 moving W at 20mph toward the Windward Islands. Overnight the system has shown little organization with the low level center becoming exposed on the NW side of a ball of deep convection. The combination of dry air to the north of the system and moderate westerly wind shear being driven by an upper level trough to the north is resulting in the poor organization. Conditions do not look to change much for the next 24-48 hours and only modest intensification is expected. It is possible that the system will not be able to overcome the unfavorable conditions and open back up into a tropical wave.

Track:

TD 5 is moving W to WNW south of a large deep layer ridge of high pressure over the central Atlantic Ocean. This ridge extends westward toward the SE US coast and TD 5 will track along the south side of this feature for the next several days. It is a fairly straight forward and medium to high confidence forecast track with the system moving through the Windward Islands on Friday and the Caribbean through the weekend into early next week. Once in the western Caribbean Sea, models begin to diverge with respect to the intensity of the high pressure over the US Gulf coast and the weakness that is expected to develop this weekend over the NE Gulf and track westward toward TX. Some of the models show a NW turn developing suggesting the weakness will be pronounced enough to slow and turn the storm, while others maintain a strong ridge and drive the system W to WNW.

Intensity:

Global models continue to remain split in keeping the system a defined tropical system or opening it back up into a tropical wave. Conditions in the short term are very marginal for development and look to continue on the marginal side for the next 2-3 days. As the system reaches the western Caribbean Sea, conditions look to become more favorable and this is noted by the SHIPS guidance bringing the system to a 75kt hurricane at that point. Interestingly, both the HWRF and especially the GFDL hurricane models do little with this system. Feel it is best to keep the system weaker, near tropical storm status, through the next 3 days, and if it survives then focus on the possibilities of better development potential in the days 4-5 period.

NHC Forecast Track and Error Cone:

[DoctorMu]

This is going to get interesting. We should still be on the underside of the high pressure ridge, which should be weakening by the weekend.

[msp]

unfortunately, looks like i will miss any potential fun with this guy. i don't arrive in CLL until the afternoon of the 16th. will be watching closely from afar if he makes it to the w/nw gulf.

[Srain]

From Jeff:

Based on data from a recon aircraft the tropical depression east of the Windward Islands is being upgraded to a tropical storm.

Discussion:

Satellite images show a slight improvement in the overall organization of the system today, but the system still lacks well defined deep convection near the center. Recon aircraft found 45kt winds with the SFMR equipment and thus the main reasoning for the upgrade. With that said, the outflow has improved to the north and while dry air is still getting entrained into the circulation it appears to not be as severe as yesterday. Ernesto continues to move quickly toward the W at near 20mph.

Track:

There has been no change in the forecast track reasoning with the system embedded south of strong mid Atlantic deep layer ridging resulting in a fairly quick W to WNW motion for the next 5 days. This will take Ernesto across the Windward Islands on Friday and through much of the eastern and central Caribbean Sea this weekend into the western Caribbean Sea south of Jamaica on Monday. At that point a weakness in between the sub-tropical ridge over the Atlantic and the retreating ridge over the southern plains/TX will begin to allow the system to slow and turn toward the WNW or NW as it nears the Yucatan. Global model track guidance is in fair to good agreement through 72 hours and this is an above average forecast confidence track.

Intensity:

It appears that Ernesto is wining out over the dry air and shear and at least holding its own in the face of moderately favorable conditions. Would like to see more deep convection near the center, but that will come in time as the inner core begins to consolidate. Models are still at odds and many lose the system/weaken it into an open wave in the Caribbean Sea, but thus far the system has overcome the negative factors and is gradually becoming better organized. Feel slow intensification is possible through the eastern and central Caribbean which is usually an unfavorable region for TC’s. Once in the western Caribbean Sea, conditions appear very favorable for intensification with a building 200mb anticyclone over the system and this feature looks to move with the system into the Gulf of Mexico. SHIPS intensity guidance brings Ernesto now to a 80kt (90mph) hurricane as it nears the Yucatan coast. It should be noted that both the EURO and GFS continue to show a weak system in the western Caribbean Sea.

It is becoming increasingly possible that a hurricane will be moving toward/into the southern or SE Gulf of Mexico middle to late next week.

Now would be a good time to remind all residents to check those hurricane kits and go over your hurricane preparation plans.

[Srain]

HPC morning Update:

THE BIGGEST ISSUE/PROBLEM THIS FORECAST PERIOD IS ERNESTO...WHICH

THE 12Z GLOBAL ENSEMBLE GUIDANCE WANTS TO TAKE THROUGH BELIZE/THE

YUCATAN PENINSULA INTO THE BAY OF CAMPECHE...WHICH IS A BIT

SOUTHWEST OF THE NHC TRACK...WHICH MID PERIOD IS CLOSEST TO THE

00Z CANADIAN MODEL THAT ULTIMATELY TAKES THE STORM TOWARDS THE

UPPER TEXAS COAST. THE CONFIGURATION OF THE RIDGE OUT WEST AND A

PRECEDING UPPER LEVEL LOW COULD LURE ERNESTO UP TOWARDS THE 30TH

PARALLEL...BUT THAT ASSUMES A SYSTEM OF HURRICANE STRENGTH WHICH

IS MINIMALLY SHEARED. COMPROMISES WERE MADE BETWEEN THE ENSEMBLE

CLUSTERING AND THE CANADIAN MODEL...WITH SOME INPUT GATHERED FROM

NHC ON THE 08Z CONFERENCE CALL WHICH CAUSED SOME SLIGHT SLOWING.

FOR NOW...ITS PRESSURE HAS BEEN DRAWN DOWN BELOW 1000 HPA TO

INDICATE A SYSTEM OF HURRICANE STRENGTH...BUT ITS FUTURE DEPENDS

ON WHETHER OR NOT IT CAN EFFECTIVELY FIGHT THE VERTICAL WIND SHEAR

THAT THE LOW LEVEL JET STEERING THE SYSTEM QUICKLY WESTWARD

IMPARTS ON THE CYCLONE DURING THE NEXT COUPLE DAYS. STAY TUNED TO

THE LATEST ADVISORIES FROM NHC CONCERNING ERNESTO.

[Srain]

Morning e-mail from Jeff:

Tropical storm passing through the Windward Island with strong winds.

Discussion:

Ernesto moving through the Windward Islands. Winds gusted to 63mph at St Lucia and sustained winds of 43mph at Barbados in the last few hours. Ernesto is racing westward at 24mph this morning…very fast for a tropical cyclone…and the result in a disorganized system even though some strong winds are being reported on the islands. First few visible images this morning show a sheared system with an exposed low level center to the west of a small and decreasing ball of deep convection. The fast forward motion of the low level center is pushing the center out from under the deep convection and the net result is about 20kts of shear over the system. While the system is well defined on radar, it is not well organized and will have to slow its fast forward motion. It is possible that Ernesto may open up into a tropical wave over the next 24 hours.

Track:

Ernesto remains to the south of a very strong mid Atlantic ridge resulting in the fast forward motion, and this should continue for the next 1-2 days taking the system generally W to WNW through the eastern and central Caribbean Sea. BY the end of day 3 (Sunday) the system will begin to approach the western edge of the sub-tropical high over the SW Atlantic and start to encounter a weakness over the Gulf of Mexico. This weakness which is currently over the SE US will be moving westward this week as the TX high pressure cell builds/moves westward. The GFS and EURO take a weak system into the southern Yucatan and then MX while the CMC, UKMET, GFDL, and HWRF all show Ernesto turning NW into the weakness. The reasoning for the spilt in the guidance at the longer range is the intensity of the system. A weaker system will follow the low level flow and stay southward, while a stronger system feels the weakness in the ridge and begins to bend WNW and then NW. Current NHC track is pretty much down the middle road of the guidance with the GFS and EURO on the left and the GFDL and HWRF on the right. The track forecast for the next 48 hours is fairly high confidence, but the confidence lowers after 48 hours as the guidance spread becomes increasingly large.

Intensity:

The intensity forecast remains a problem as the near term environment is marginally favorable for development and the long term environment favorable. The question is does Ernesto survive the short term to take advantage of the long term. Based on the satellite presentation this morning it is questionable if Ernesto will survive the next 24 hours as the fast westward motion will continue to produce moderate to strong wind shear. Additionally, the eastern Caribbean Sea is typically not a very favorable region for developing tropical systems. Also the GFS and EURO continue to insist that the system will not intensify much, while the latest GFDL, HWRF, and CMC all show Ernesto reaching hurricane intensity in the western Caribbean Sea. Current NHC forecast is leaning toward the stronger guidance and takes Ernesto to a hurricane south of Jamaica and into the NE Yucatan and the SE Gulf of Mexico. It should be noted that conditions will be fairly favorable in the western Caribbean Sea and the LGEM and GFDI guidance makes Ernesto a major hurricane. It is also noted that most of the guidance makes Ernesto a category 2 hurricane about 48 hours prior to the official NHC forecast.

Now would be a good time for residents to review their hurricane preparation plans!

90L:

New tropical wave/surface low south of the Cape Verde Islands has developed some organized thunderstorms and continues to show signs of development this morning. NHC gives this system a 30% chance of tropical cyclone formation as it moves WNW at 10-15mph.

Forecast Model Tracks:

[DoctorMu]

Excellent report. Maintenance of current forward motion might suggest a southern solution, but we'll see...

[Ed Lizard]

Excellent report. Maintenance of current forward motion might suggest a southern solution, but we'll see...

When the GFS and Euro are on the same general page...

Be interesting to see if Euro kills it completely or if it can make it to the BoC...

[Srain]

Afternoon update from Jeff:

New area of disturbed weather has developed off the SE FL coast today as a tropical wave interacts with an upper level trough. While upper levels winds are not overly favorable for development they will become more favorable over the next 24 hours as the system moves toward the NW at 5-10mph.

Ernesto:

No significant changes today with respect to track or forecast intensity. Still possible we will be seeing a hurricane nearing the S/SE Gulf middle of next week.

[DoctorMu]

When the GFS and Euro are on the same general page...

Be interesting to see if Euro kills it completely or if it can make it to the BoC...

Yeah, the Euro has Ernesto pulling a Kaiser Sozé on the Honduran Nicaragua border after 144 hours out.

GFS is not much kinder, does have the low/wave retrograding from FL west to near the Texas coast...

Hmmmm...the NHC maintaining a deviation with GFS and Euro in the prognosis:

THERE IS NO

CHANGE TO THE SYNOPTIC REASONING FROM THE PREVIOUS FORECAST AS THE

CYCLONE REMAINS EMBEDDED WITHIN A FAST EASTERLY FLOW SOUTH OF THE

SUBTROPICAL RIDGE. THIS STEERING PATTERN SHOULD KEEP THE CYCLONE ON

A GENERAL WESTWARD TRACK FOR THE NEXT COUPLE OF DAYS. AFTER

THAT...THE RIDGE WILL PROBABLY WEAKEN SOMEWHAT...CAUSING ERNESTO TO

SLOW DOWN AND GAIN A LITTLE LATITUDE. HOWEVER...TRACK MODELS HAVE

A LARGE SPREAD IN THE LONG TERM WITH LARGE DIFFERENCES IN THE

STRENGTH OF THE RIDGE. THE OFFICIAL FORECAST IS NUDGED TO THE

WEST...AND LIES ON THE SOUTH SIDE OF THE MODEL CONSENSUS. ALTHOUGH

THE NHC FORECAST IS WELL TO THE NORTH OF THE NORMALLY RELIABLE GFS

AND ECMWF MODELS...THESE MODELS ARE SHOWING A RATHER WEAK SYSTEM IN

A FEW DAYS...AND ARE NOT THOUGHT TO BE THE MOST REPRESENTATIVE IN

THIS CASE.

[Srain]

Another update from Jeff:

Strong high pressure over the area will be moving NW over the weekend allowing the area to come under the influence of troughing over the NE Gulf of Mexico.

The retreating high will allow moisture and weak disturbances to move into the area from the east starting on Sunday. This will help cool afternoon temperatures from the upper 90’s into the low to mid 90’s and bring a 20-30% chance of rainfall into the forecast.

Early next week shows the ridge remaining anchored to our west with a downstream trough developing over the eastern US and a weakness in the ridge over E TX/LA. Moisture associated with the area of tropical weather E of FL this afternoon may get pushed westward toward SE TX toward Tuesday of next week. There is some potential that this system my try and develop into a closed circulation and that would have some bigger impacts to the area if it were to make it this far west. With the main ridge off to our NW, expect a continued chance of daily showers and thunderstorms along the seabreeze.

Extended:

All eyes will be on TS Ernesto and its track into the Gulf of Mexico and what if any impacts it may have on the TX coast. For now any impacts would be beyond next Thursday.

[DoctorMu]

Another update from Jeff:

Strong high pressure over the area will be moving NW over the weekend allowing the area to come under the influence of troughing over the NE Gulf of Mexico.

The retreating high will allow moisture and weak disturbances to move into the area from the east starting on Sunday. This will help cool afternoon temperatures from the upper 90’s into the low to mid 90’s and bring a 20-30% chance of rainfall into the forecast.

Early next week shows the ridge remaining anchored to our west with a downstream trough developing over the eastern US and a weakness in the ridge over E TX/LA. Moisture associated with the area of tropical weather E of FL this afternoon may get pushed westward toward SE TX toward Tuesday of next week. There is some potential that this system my try and develop into a closed circulation and that would have some bigger impacts to the area if it were to make it this far west. With the main ridge off to our NW, expect a continued chance of daily showers and thunderstorms along the seabreeze.

Extended:

All eyes will be on TS Ernesto and its track into the Gulf of Mexico and what if any impacts it may have on the TX coast. For now any impacts would be beyond next Thursday.

91L showing Ernesto the way, and watering a few lawns

[PottercountyWXobserver]

Ernesto has me super excited right now. The potential with this one is intriquing! Dear Ernesto, did you know Houston is spanish for bullseye, so you know what you have to do

[Ed Lizard]

With Ernesto only 1006 mb despite impressive flair, and 850 mb center a bit West of where I would have guessed based on IR imagery, perhaps the weaker/further South globals are the way to go.

Its early, and on the main Ernesto thread Steve posted some ensembles that suggest the coast isn't completely clear yet.

[Srain]

06Z NCEP Ensembles:

[Ed Lizard]

Ensembles obviously suggest it isn't case closed, but my amateur hunch is that the 6Z GFS is very close to the actual track. I was giving the tropical models a chance when it looked like Ernesto was going to town on satellite, but now that it is a 1006 or 1007 mb storm, and the GFDL initialized 8 or 9 mb too strong, making it more prone to move toward mid-latitude weakness than the actual Ernesto, IMHO, North of Belize border but well South of Cancun, and a second, probably stronger, landfall general vicinity Tampico.

[DoctorMu]

Ernesto and its fate remain an enigma wrapped in a mystery. It appears stronger, but the latest recon finds the storm weakening slightly instead of strengthening. Will it decouple as the Euro suggests? The Yucatan Channel solution appears less likely now. This is tricky - there's dry air ahead but little shear.

However, Ernesto appears to losing a bit of moisture

WTNT45 KNHC 041445

TCDAT5

TROPICAL STORM ERNESTO DISCUSSION NUMBER 12

NWS NATIONAL HURRICANE CENTER MIAMI FL AL052012

1100 AM AST SAT AUG 04 2012

DESPITE THE EXCELLENT PRESENTATION ON SATELLITE WITH CYCLONICALLY

CURVED CONVECTIVE BANDS AND A WELL ESTABLISHED UPPER-LEVEL

OUTFLOW...DATA FROM A RECONNAISSANCE PLANE INDICATE THAT

ERNESTO HAS NOT BECOME ANY BETTER ORGANIZED. IN FACT...THE WINDS

HAVE DECREASED TO 45 KT AND THE PRESSURE HAS RISEN TO 1008 MB. I

DO NOT HAVE ANY REASONS FOR THE CURRENT WEAKENING BUT I HAVE NO

REASON TO FORECAST ADDITIONAL WEAKENING EITHER. THE SHEAR IS

ANTICIPATED TO REMAIN LOW ACROSS THE CARIBBEAN...AND ERNESTO WILL

MOVE OVER AN OCEAN WITH HIGHER HEAT CONTENT. GIVEN SUCH

CONDITIONS...THE OFFICIAL FORECAST CALLS FOR ERNESTO TO BECOME A

HURRICANE IN THE WESTERN CARIBBEAN. THIS FORECAST IS UNCERTAIN

SINCE MODELS ARE IN DISAGREEMENT. SHIPS...LGEM AND THE GFDL

FORECAST ERNESTO TO BECOME A HURRICANE WHILE THE HWRF EITHER

FORECASTS NO CHANGE OR WEAKENING.

ERNESTO IS MOVING TOWARD THE WEST-NORTHWEST OR 285 DEGREES AT 16

KNOTS EMBEDDEED IN THE FLOW SOUTH OF THE SUBTROPICAL RIDGE. THIS

TRACK IS EXPECTED TO CONTINUE FOR THE NEXT 24 TO 48 HOURS. AFTER

THAT...THERE WILL PROBABLY BE A WEAKENING OF THE RIDGE AND ERNESTO

COULD TURN A LITTLE MORE TO THE NORTHWEST TOWARD THE YUCATAN

PENINSULA AND THE BAY OF CAMPECHE. MODELS ARE IN GOOD AGREEMENT

WITH THIS SCENARIO DURING THE NEXT TWO DAYS...BUT BEYOND THAT

TIME...THERE ARE LARGE DIFFERENCES. BOTH THE GFDL AND HWRF TURN

ERNESTO NORTHWARD...AND THE RELIABLE GLOBAL MODELS KEEP THE CYCLONE

ON A WEST-NORTHWEST TRACK. THE OFFICIAL FORECAST IS HEAVILY BIASED

TOWARD THE GLOBAL MODELS AND IS VERY SIMILAR TO THE PREVIOUS NHC

FORECAST.

FORECAST POSITIONS AND MAX WINDS

INIT 04/1500Z 14.4N 68.7W 45 KT 50 MPH

12H 05/0000Z 14.8N 71.2W 45 KT 50 MPH

24H 05/1200Z 15.5N 74.5W 50 KT 60 MPH

36H 06/0000Z 15.7N 77.5W 65 KT 75 MPH

48H 06/1200Z 16.5N 80.5W 70 KT 80 MPH

72H 07/1200Z 18.0N 84.0W 80 KT 90 MPH

96H 08/1200Z 19.5N 87.0W 70 KT 80 MPH

120H 09/1200Z 22.0N 90.5W 60 KT 70 MPH

[Srain]

Update from Jeff:

The government of Jamaica has issued a Tropical Storm Warning

Discussion:

While the satellite presentation of Ernesto looks very good with deep thunderstorms over the center and well defined banding features, the recon. aircraft this morning has determined that in fact the storm has weakened with the central pressure increasing from 1002mb yesterday to 1008mb this morning and flight level winds of 40-45kts. It is currently unknown why Ernesto is having such a hard time with almost all factors supporting development (increasingly good upper level outflow, very warm water temperatures, little to no wind shear, and an expanding area of moisture surrounding the inner core). There continues to be a mass of dry air west of the system and from time to time this appears to becoming entrained into the circulation and possibly explaining the weakening this morning. Additionally, tropical systems tend to struggle in this section of the Caribbean Sea possibly due to the inflow of air off South America. Anyhow, the satellite patterns continues to look good and the next aircraft this afternoon may find a slightly stronger system. It should be noted, that as stated several times over the last few days, much of the global model guidance weakened the system in this region and in fact they appear to have been on the right idea all along.

Track:

There has been little change in the track reasoning for the next 48 hours with Ernesto south of a ridge of high pressure over the central Atlantic to off the Bahamas. This will maintain a W to WNW heading for the next 48 hours taking the system south of Jamaica and toward the western Caribbean Sea. After 48 hours the ridge over the SW ATL begins to break down with a weakness across the northern Gulf of Mexico between the high over the SW ATL and the high moving westward from the plains. Overnight, the main global guidance of the GFS, EURO, UKMET, and NOGAPS have all trended southward with Ernesto continuing on a W to WNW course across the Yucatan and the Bay of Campeche and then into central MX. The GFS and EURO have been very consistent on this reasoning the last few days. The hurricane models: the GFDL and HWRF have Ernesto feeling the weakness and turning NW to NNW toward the US Gulf coast. It is hard to ignore the reliable guidance taking Ernesto westward and the NHC forecast follows closely to the center of the guidance cluster, but is to the right of the consensus out of respect for the two eastern outlier models the GFDL and HWRF as well as some of the GFS and EURO ensembles which are to the north of the operational guidance tracks. Track confidence is high through 48 hours and then the confidence greatly decreases.

Intensity:

While factors appear favorable for intensification, Ernesto has struggled to consolidate its inner core and utilize the warm ocean and favorable upper air conditions. If in fact the dry air to the west of the system is the culprit for the lack of organization, then this will likely continue for the next 24 hours or so. Conditions will be favorable for intensification and the system will be moving across some very deep warm waters in the western Caribbean Sea. Again the models are at odds with the global models keeping the system weak while the SHIPS, LGEM, and GFDL guidance make Ernesto a hurricane. The official forecast continues to bring the system to a 90mph hurricane prior to landfall on the Yucatan and then weakening into a tropical storm while crossing the Yucatan. This intensity forecast is low confidence.

Now would be a good time to review your hurricane preparation plans and make sure hurricane kits are fully stocked.

TS Florence:

The area of low pressure in the far eastern Atlantic Ocean has been upgraded to TS Florence overnight. This storm is expected to track WNW over the open Atlantic into cooler waters and gradually weaken over the next 5 days.

NHC Forecast Track and Error Cone: