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Atlantic Tropical Action 2013


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#806
Ed Lizard

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Looks, if anything, like it could be experiencing Easterly shear.

 

OT

 

GFDL ensembles.

 

I hadn't heard...

 

  • Goal: Design and run a simple ensemble based on the operational GFDL model to provide additional real-time guidance on track and intensity.
  • Method: Run at same resolution as the operational GFDL model [parent domain and 2 nests with 1/2° (~55 km), 1/6° (~18 km), and 1/12° (~9 km) horizontal grid spacing, respectively]. Apply perturbations by either modifying the vortex structure, moisture fields, or sea-surface temperatures (SSTs) in the core region, as well as by modifying the model physics.
  • Resources: All forecasts run on NOAA's Jet machine at Earth System Research Laboratory (ESRL) in Boulder, CO.

GTE_ISAAC09L_2012082506_track_and_intens

Attached Files



#807
Snowlover123

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Up to 40% at 8 AM.

#808
phil882

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If you look at the last few visible frames, there is some evidence there is a tighter low-level vortex (around 9.5N, 42W) that is still partially observed by the convection.

 

2dvllkk.gif



#809
Mike.Ventrice

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If you look at the last few visible frames, there is some evidence there is a tighter low-level vortex (around 9.5N, 42W) that is still partially observed by the convection.

 

2dvllkk.gif

uh-oh... I see a naked swirl alert... :( look to the north of the deep convection.. but yeah Phil, def some sort of ll vortex there



#810
phil882

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uh-oh... I see a naked swirl alert... :( look to the north of the deep convection

 

Yep... as the system continues to gain latitude its also accelerating further as the low-level flow becomes enhanced by the trades. The upper level flow is going to have a difficult time keeping up over the next few days, not unlike Ernesto the first 24 or so hours of its life. 

 

6h8inn.gif



#811
Mike.Ventrice

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It's not a guarantee since we are in a favorable low-frequency MJO state, but will the invest be able to fend off the approaching upper-level convergent CCKW phase about to superimpose with the system? Right now, we might expect a period of enhanced low-level westerly flow and upper-level easterly flow impacting the system, but it should eventually swap to enhanced trades and increased upper-level westerly flow in a day or two...

 

28.gif



#812
Levi32

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ASCAT pass reveals that little vortex is not actually closed, but the wave axis is very sharp. It should open up a bit more though as the system gains latitude and enters the main trade wind belt.

 

WMBds113.png



#813
wxmeddler

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Air Force HH's scheduled to start flights tomorrow with today's TCPOD.

NOUS42 KNHC 071607
REPRPD
WEATHER RECONNAISSANCE FLIGHTS
CARCAH, NATIONAL HURRICANE CENTER, MIAMI, FL.
1200 PM EDT SUN 07 JULY 2013
SUBJECT: TROPICAL CYCLONE PLAN OF THE DAY (TCPOD)
         VALID 08/1100Z TO 09/1100Z JULY 2013
         TCPOD NUMBER.....13-037

I.  ATLANTIC REQUIREMENTS
    1. SUSPECT AREA (NEAR WINDWARD ISLANDS)
       FLIGHT ONE -- TEAL 70      FLIGHT TWO -- TEAL 71
       A. 08/2100Z                A. 09/1200Z,1800Z
       B. AFXXX 01BBA INVEST      B. AFXXX 0203A CYCLONE
       C. 08/1815Z                C. 09/1030Z
       D. 12.5N 54.7W             D. 14.0N 60.8W
       E. 08/2030Z TO 09/0030Z    E. 09/1130Z TO 09/1800Z
       F. RESOURCES PERMITTING

    2. OUTLOOK FOR SUCCEEDING DAY: CONTINUE 6-HRLY FIXES WHILE
       SYSTEM REMAINS A THREAT.

II. PACIFIC REQUIREMENTS
    1. NEGATIVE RECONNAISSANCE REQUIREMENTS.
    2. OUTLOOK FOR SUCCEEDING DAY.....NEGATIVE.

$$
SEF


#814
TropicalAnalystwx13

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95L isn't the only one in town. Check out what becomes of the wave currently over central Africa:

 

gfsfull_pres_wind_atltropics_64.png



#815
Alfoman

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CODE RED EVERYONE 

 

ZCZC MIATWOAT ALL
TTAA00 KNHC DDHHMM

TROPICAL WEATHER OUTLOOK
NWS NATIONAL HURRICANE CENTER MIAMI FL
200 PM EDT SUN JUL 7 2013

FOR THE NORTH ATLANTIC...CARIBBEAN SEA AND THE GULF OF MEXICO...

1. A STRONG TROPICAL WAVE LOCATED ABOUT 1150 MILES EAST-SOUTHEAST OF
THE WINDWARD ISLANDS IS MOVING WESTWARD AT 25 MPH. SHOWER AND
THUNDERSTORM ACTIVITY CONTINUES TO SHOW SIGNS OF ORGANIZATION...
AND RECENT SATELLITE WIND DATA INDICATE THAT A CLOSED SURFACE
CIRCULATION MAY BE FORMING. ENVIRONMENTAL CONDITIONS ARE CONDUCIVE
FOR FURTHER DEVELOPMENT OF THIS DISTURBANCE...AND A TROPICAL
DEPRESSION OR A TROPICAL STORM COULD FORM AT ANY TIME...WHICH WOULD
REQUIRE A TROPICAL STORM WATCH OR WARNING FOR PORTIONS OF THE
LESSER ANTILLES. THIS SYSTEM HAS A HIGH CHANCE...60 PERCENT...OF
BECOMING A TROPICAL CYCLONE DURING THE NEXT 48 HOURS.

ELSEWHERE...TROPICAL CYCLONE FORMATION IS NOT EXPECTED DURING THE
NEXT 48 HOURS.

$
FORECASTER STEWART
NNNN



#816
Superstorm93

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While this will not be some major huricane that blasts through the islands, it is however just an appetizer for whats to come later in the season. 

 

Just like Colin crapped out in 2010, this may do the same thing after a day or two of being classified

 



#817
wxmeddler

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Ch-Ch-Ch Cherry time!



#818
Srain

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95L that is currently racing across the Central Atlantic at about 25 MPH. This is awfully fast for a wave to travel and it would need to slow its forward motion before any real development can be expected. There is a chance after it enters the Caribbean Sea next weekend and approaches the NW Caribbean conditions become a bit more conducive for development. The ensembles are suggesting a rather potent 500mb upper low near the Northern Gulf Coast at that time, but a lot of caution is recommended as we know how wrong the longer range guidance can be. Some features that are favorable for development later on is the MJO and the relaxing of the easterly trade winds the closer this disturbance makes it to the Western Caribbean.



#819
GaWx

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The MJO, itself, is still a plus for development possibilities fwiw. It remains in phase 2 with some backing up in the direction of phase 1. As long as it mainly stays in 2 for at least several more days and doesn't go and stay back into phase 1, I'll continue to view the MJO, itself, as a positive and suggesting about a 50% chance for 95-L to develop over the next 5-6 days. For July, 50% chance over 5-6 days is much higher than climo.
 

 Most of the time in July, MJO phase 2 moves into the circle rather than across to phase 3. That is reflected by the fact that there have been 68 July phase 2 days since 1995 vs. only 24 phase 3 days (~3 times as many days in 2 vs. 3). There have been 12 periods of phase 2 during July since 1995. Nine of these 12 (75%) subsequently went into the circle and 3 of the 12 (25%) went over to phase 3. So, the circle is my best guess as of now as to where the MJO will be in about 7-10 days. We'll see.

There have been five July phase 2 geneses that lead to CONUS H hits since 1995. The MJO's for these all went into the circle from phase 2 rather than go into phase 3 fwiw.



#820
Superstorm93

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00z ECMWF Ensembles 

 

NW Caribbean isn't looking too likely 

 

 

EDIT: A wave with 35 knot winds? Cool

 

AL, 95, 2013070718, , BEST, 0, 98N, 438W, 35, 1008, WV, 34, NEQ, 30, 0, 0, 30, 1013, 150, 20, 0, 0, L, 0, , 0, 0, INVEST, M, 

 

 

eemn2013070700atl.gif



#821
Srain

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Conditions remain hostile until this disturbance gets further W. The 12Z NCEP Ensemble TC Genesis probs suggest conditions may improve across the NW Caribbean.

Attached Files



#822
Jim Marusak

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how much of a wild-card and shear problem is being tossed in here with that upper/mid-level low approaching the bahamas that looks to head through florida in the next 48 hours or so? because if the synoptic models are anywhere close on how they handle it, they're going to extend the current ohio valley upper trough further south causing either a wider turn into the southern gulf or more likely a bounce into the gulf stream without getting to the US.



#823
phil882

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Its probably not unreasonable to suggest that 95L is close or at TD intensity. If there isn't a closed circulation, its pretty darn close. It is worth noting however that the deepest convection has shifted from the W quadrant to the S quadrant, indicating a shift in the shear direction from easterly to northerly. If this counter clockwise rotation in the shear continues, the shear will become increasingly northwesterly, and this is more unfavorable than easterly shear since it will also advect drier SAL infested air from higher latitudes. 

 

2sba1b9.jpg



#824
Scott747

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Just a quick hit on some modeling info. 18z parallel HWRF run which goes operational next Monday. Major improvements, especially on intensity.

 

The model has been extensively tested with a combination of all

the upgrades listed above for a 3-year sample of cases. The

results showed impressive and remarkable results. For Atlantic

basin track, the HWRF is improved by ~5-15% and now appears

competitive with the GFS. For intensity, the model reduces errors

by ~15%, has demonstrated skill greater than that of the NHC

official forecast and greater than that of the statistical

models. Similar improvements are noted for the Eastern North

Pacific basin as well. 

 

INVEST95L2013070718fsct.png



#825
TropicalAnalystwx13

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Still not closed.

 

Plenty of tropical storm-force winds though. Straight to Chantal when it gets a closed low.

 

20130708_00_25_flag.gif



#826
TropicalAnalystwx13

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butttttt....

 

AL, 03, 2013070800, , BEST, 0, 100N, 460W, 30, 1008, TD, 34, NEQ, 0, 0, 0, 0, 1013, 150, 20, 0, 0, L, 0, , 0, 0, THREE, M,

#827
wxmeddler

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That convection has been going strong for the past 4-5 hours now.



#828
TropicalAnalystwx13

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Modified to TS Chantal.

 

AL, 03, 2013070800, , BEST, 0, 97N, 461W, 35, 1008, TS, 34, NEQ, 30, 0, 0, 30, 1013, 150, 20, 0, 0, L, 0, , 0, 0, CHANTAL, M

#829
Superstorm93

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And it goes straight to tropical storm Chantal

 

I never really was fond of this name (for a tropical system)

 

CHANTAL, AL, L, , , , , 03, 2013, TS, O, 2013070606, 9999999999, , , , , , METWATCH, , AL032013

 


#830
phil882

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Still not closed.

 

Plenty of tropical storm-force winds though. Straight to Chantal when it gets a closed low.

 

20130708_00_25_flag.gif

 

That is a closed albiet elongated circulation... note the westerly winds around 8N 47W. This could be due to the center attempting to relocated further south under the deeper convection. As is, the circulation looks to be on the northern edge of the convection still, similar to the microwave pass earlier.



#831
Superstorm93

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That is a closed albiet elongated circulation... note the westerly winds around 8N 47W. This could be due to the center attempting to relocated further south under the deeper convection. As is, the circulation looks to be on the northern edge of the convection still, similar to the microwave pass earlier.

 

The 23z pass showed that it was closed

 

It may have, like you suggested, relocated further south

 



#832
wxmeddler

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You may now take your discussion over to a dedicated thread and leave this one for future invest's. :)

 

http://www.americanw...-storm-chantal/



#833
mp184qcr

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Modified to TS Chantal.

 

AL, 03, 2013070800, , BEST, 0, 97N, 461W, 35, 1008, TS, 34, NEQ, 30, 0, 0, 30, 1013, 150, 20, 0, 0, L, 0, , 0, 0, CHANTAL, M

 

do you have the link to where to get this data from?



#834
phil882

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do you have the link to where to get this data from?

 

http://ftp.nhc.noaa.gov/atcf/tcweb/



#835
Mike.Ventrice

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Hi guys, here's an email I sent out to the t-storm list folks... thought I'd share it here.
 
The GFS operational model is indicating a potential eastern MDR-type genesis event coming up in 2-3 days.  This shows up pretty nicely in maps of GFS rainfall/925 hPa vorticity/200 mb wind maps:
 
What's interesting is the GFS op is indicating that convection will fire up just off the coast of West Africa between 06-12Z tomorrow, forming an area of low-level cyclonic vorticity over the ocean. This times well with the coherent diurnal cycle of convection at the West Africa coast, where convection is most prominent over the ocean, straddling the coast of West Africa between 06-12Z, with a minimum of convection over the coastal region. 
 
The GFS then fires up afternoon convection downstream of the Guinea Highlands region, or more specifically the Fouta Djallon's, between 15-21Z, also developing a low-level cyclonic relative vorticity signature. At this time, the model keeps the convection active over the ocean. Between 06-12Z July 10, the GFS suggests that the vorticity centers will merge just off the coast of West Africa, and what looks to be a depression or tropical storm spins up soon after.
 
Alan Brammer's dprog(dt) maps indicates that there's a moderate-strong African easterly wave propagating across West Africa and out over the Atlantic during this interaction: http://www.atmos.alb.../abrammer/maps/
 
This also times well with a strong MJO event currently over the Indian Ocean (http://www.atmos.alb...m.MJO.5S-5N.png; VP200 anomalies shaded, MJO filtered VP200 anomalies contoured where dashed = upper-level divergent phase of the MJO), suggestive that the Atlantic is in an intraseasonal state favorable for increased African easterly wave activity and also developing tropical cyclones. 
 
Now the only thing that worries me is there is a 2 standard deviation convectively suppressed atmospheric Kelvin wave pushing over the western MDR. Currently, the eastern Atlantic/West Africa is still in a state relative to the suppressed Kelvin wave where the upper-level easterly, low-level westerly wind phase will be impacting the region for the upcoming few days... http://www.atmos.alb...c_analyses.html
 
This relative Kelvin wave location, in conjunction to the robust AEW pushing across Africa and the state of the MJO, may all act together to spin up an east Atlantic storm... however there will only be a 2-3 day window. If the GFS verifies, it will be a very big "win" in the modelling community to correctly represent the current, complex state of convection in the tropics. 
 
That being said, I do have some concerns with the forecast beyond 2-3 days, as the GFS has been dropping the ball with propagating the strong suppressed Kelvin wave phase eastward once in forecast mode:
http://www.atmos.alb...ELVIN.5S-5N.png (VP200 anomalies shaded, Kelvin filtered VP200 anomalies contoured where warm colors = upper-level divergent phase of the Kelvin wave).
 
For the past week, the model has been holding the convectively active phase of the MJO/CCKW over Africa instead of continuing it off to the east. You can see this clearly in the 1-week MJO phase-space diagram verification maps that the CPC puts out: http://www.cpc.ncep....lidphase-W1.gif
 
I've noticed, and I'm sure others have as well, that land masses such as S. America, Africa, and the Maritime Continent, tends to act as a barrier for the eastward propagation of the MJO/CCKWs. It appears that this is happening again, holding the negative VP200 anomaly stationary over Africa instead of bringing that suppressed Kelvin wave across the region (http://www.atmos.alb...om.30.5S-5N.gif).
 
Nevertheless, I will be watching this case quite closely as it has a lot of similarities to the 2006 Tropical Storm Debby Case (with the main exception that instead of an upstream suppressed Kelvin wave phase, it was the convectively active phase of a CCKW passing).


#836
TropicalAnalystwx13

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18z GFS full-res has a hurricane from the wave in just a week. 

 

Will this system struggle with fast motion like Chantal currently is?

 

6cKxcUb.png



#837
phil882

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I continue to remain skeptical of the cape verde wave until the ECMWF comes onboard (it hasn't). We saw this several times last year that the GFS was trigger happy with waves emerging off the African coast, only to be substantially delayed in development (Isaac) or not develop all together. Its still middle July... I'm siding with climatology on this one. 

 

To support that, AEW's often need the benefit of both being in a diurnally active phase for convection, as well as a favorable equatorial wave pattern. Over land the diurnal max is typically in the mid-late afternoon and over the ocean the diurnal max in convection takes place near daybreak. The wave is emerging this morning off the African coast, but thus far the convection hasn't been overly impressive. The eastward propagating subsiding leg of a CCKW probably will not help matters. I think Mike is correct that the GFS is likely failing to propagate this Kelvin wave eastward very well in velocity potential, and this could be potentially leading to a bad forecast with regards to TCG in the far East Atlantic. 



#838
Mike.Ventrice

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I continue to remain skeptical of the cape verde wave until the ECMWF comes onboard (it hasn't). We saw this several times last year that the GFS was trigger happy with waves emerging off the African coast, only to be substantially delayed in development (Isaac) or not develop all together. Its still middle July... I'm siding with climatology on this one. 

 

To support that, AEW's often need the benefit of both being in a diurnally active phase for convection, as well as a favorable equatorial wave pattern. Over land the diurnal max is typically in the mid-late afternoon and over the ocean the diurnal max in convection takes place near daybreak. The wave is emerging this morning off the African coast, but thus far the convection hasn't been overly impressive. The eastward propagating subsiding leg of a CCKW probably will not help matters. I think Mike is correct that the GFS is likely failing to propagate this Kelvin wave eastward very well in velocity potential, and this could be potentially leading to a bad forecast with regards to TCG in the far East Atlantic. 

 

Phil, there will be a number of things we need to watch very closely... One is if the convection over the ocean stays on during the afternoon. The second is if we see afternoon convection fire up downstream of the Guinea Highlands between 15-23Z and propagate somewhat north and west, spiraling off the coast of Senegal and merge with the oceanic convection. The center of the suppressed CCKW is still well over the western MDR and thus the eastern Atlantic/west Africa is in a state favorable for convection, low-level relative vorticity, but moderate vertical wind shear (which may not be bad for genesis).

 

So it remains to be see if the GFS is correctly depicting the diurnal cycle of convection over the coast of West Africa. That will be the key!

The European does spin up a nice low-level vorticity signature, but over the central-western MDR... not up along the coast of West Africa. Due to the abnormally strong gulf of guinea cold tongue, I still feel the chances of an up-close and person genesis type storm near West Africa is lower than average. But time will only tell in the next 24 hours how the diurnal cycle of convection behaves...



#839
thewxmann

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I continue to remain skeptical of the cape verde wave until the ECMWF comes onboard (it hasn't). We saw this several times last year that the GFS was trigger happy with waves emerging off the African coast, only to be substantially delayed in development (Isaac) or not develop all together. Its still middle July... I'm siding with climatology on this one. 

 

To support that, AEW's often need the benefit of both being in a diurnally active phase for convection, as well as a favorable equatorial wave pattern. Over land the diurnal max is typically in the mid-late afternoon and over the ocean the diurnal max in convection takes place near daybreak. The wave is emerging this morning off the African coast, but thus far the convection hasn't been overly impressive. The eastward propagating subsiding leg of a CCKW probably will not help matters. I think Mike is correct that the GFS is likely failing to propagate this Kelvin wave eastward very well in velocity potential, and this could be potentially leading to a bad forecast with regards to TCG in the far East Atlantic. 

 

If anything, the Euro has been trending even weaker with the CV system. GFS needs to lay off the drugs. 

 

This is a good analysis. This CCKW stuff is pretty cool.



#840
Ed Lizard

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Besides the GFS 'Dorian?' wave people aren't buying, GFS also has a nice looking wave scraping Venezuela, which, if this exists as forecast, could enter the SW Caribbean for either Atlantic or Pacific action the following week.

 

700thetae60.png







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