Development with Tropical Wave in MDR?

[gatorcane]

And another thing this run of the gfs looks almost exactly like the Euro. in that its much farther south and the trough is weaker and pulls out faster.

Indeed out through 7 days the low/wave is just north of Hispaniola headed WNW after just skirting Puerto Rico and Leewards to the north...

Since the GFS does not deepen it much through 150 hours, seems to be moving along with the low-level flow more like the Euro has it moving in the latest run.

At 192 hours it starts to recurve, different than the Euro. But it looks like it never reaches TS status on this run.

[Aric Dunn]

its lifts it out after 150 hours.. like magic though .. lol

[gatorcane]

its lifts it out after 150 hours.. like magic though .. lol

The ECMWF handles the trough differently in the long-range. The ECMWF pulls through trough out quickly between 168 and 192 hours. The GFS leaves the trough around longer allowing whatever comes of this system to recurve.

[Ed Mahmoud]

Watched the JB video. SAL and shear will not let these waves develop, for now.


But he expects what he calls a trough split (the base of a trough getting squeezed off between two ridges) and upward motion off the SE US, and if these one of these waves get into the upward motion area, they may find favorable conditions.


JoeB doesn't make a firm prediction, but would not be surprised if sometime next week we have one of his "rabbit out of a hat" developments. He doesn't name a target, but one would assume Florida to the Carolinas and beyond.

JB also states most Northeast hurricane hits follow cool weather, hot weather implies they are on the North side of a blocking ridge, and usually protected. But the trough will be in the East next week,

If these waves hit the Caribbean, fast Easterly flow will prevent development.


There is an East Coast trough next week

Weak anticyclone over the Central Bahamas with a ripping jet over Florida inducing upward motion to its East.

[cycloneye]

Hanging good so far.

[x-y-no]

its lifts it out after 150 hours.. like magic though .. lol

The ECMWF handles the trough differently in the long-range. The ECMWF pulls through trough out quickly between 168 and 192 hours. The GFS leaves the trough around longer allowing whatever comes of this system to recurve.

HPC is favoring the slower solution for now ...

THE 00Z ECMWF AND NEARLY ALL
MEMBERS OF ITS OWN ENSEMBLE SUITE ARE ABOUT 12-24 HRS FASTER THAN
THE GFS AND NEARLY ALL MEMBERS OF ITS OWN ENSEMBLE SUITE WITH THE
LOW ENTERING WESTERN CANADA... RESULTING IN MAJOR DIFFERENCES IN
POP/TEMP GRADIENTS FOR PORTIONS OF THE N. ROCKIES/N. PLAINS.
MEANWHILE...THE 00Z CANADIAN AND ITS OWN ENSEMBLE SUITE ARE
BETWEEN THESE TWO SCENARIOS...BUT GENERALLY REFLECT THE SLOWER
SOLUTION CAMP. FINALLY...THE UKMET/NOGAPS ARE SLOWER LIKE THE
GFS/CANADIAN...WHICH PLACES THE ECMWF NEAR THE FAST EDGE OF THE
GUIDANCE AND THUS CONSIDERED LEAST PROBABLE OF THE AVAILABLE
GUIDANCE...ESPECIALLY BY DAY 7. THE PREFERENCE FOR A SLOWER
SCENARIO ALSO ALLOWS THE UPPER HIGH OVER THE ROCKIES TO REMAIN
LARGER/STRONGER THAN THE ECMWF INDICATES...WHICH IS GENERALLY
PREFERRED DUE TO THE AMPLIFYING NATURE OF THE LONGWAVE FLOW AT THE
START OF THE PERIOD. OUR UPDATED PRESSURES/FRONTS USED NEARLY AN
EQUAL BLEND OF THE GFS/CANADIAN/ECMWF AS A STARTING POINT...BUT
WITH MANUAL ADJUSTMENTS MADE TO SKEW THE FRONTAL TIMING OVER THE
ROCKIES/NORTHERN PLAINS FURTHER TOWARD THE SLOWER SIDE OF THE
GUIDANCE BY DAYS 6/7.

http://www.hpc.ncep.noaa.gov/preepd/preepd.html

[Sanibel]

No doubt ITCZ is flickering on. Only question is if it is a direct turn-on or first pulse.

[JonathanBelles]

Interesting wave. It will probably poof in the next 24 hours, doesnt seem sustainable as of just yet.

[PTrackerLA]

Wave off Africa has taken center stage now. Seems to be maintaining convection and has a nice overall shape.

[cycloneye]

NHC wants to see if convection persists,thats why there is no mention in the Tropical Weather Outlook.

036
ABNT20 KNHC 141749
TWOAT
TROPICAL WEATHER OUTLOOK
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
200 PM EDT TUE JUL 14 2009

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

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

$$
FORECASTER BEVEN

[cycloneye]

The only mention of the large area of convection south of the Cape Verde islands is in the ITCZ section of the 2 PM EDT discussion.

THE ITCZ AXIS IS CENTERED ALONG 12N15W 11N28W 12N38W 8N46W
11N56W 9N62W. A LARGE CLUSTER OF NUMEROUS MODERATE/SCATTERED
STRONG CONVECTION IS FROM 7N-13N BETWEEN 18W-26W...MOST LIKELY
ASSOCIATED WITH THE NEXT TROPICAL WAVE.

http://www.storm2k.org/weather/hw3.php? ... hwvmetric=


If convection persists for 12-24 hours,they will start to mention it.

[Derek Ortt]

12Z GFS still thinks the western wave is the frontrunner. That does not appear to be the case.

The long-range GFS runs as to where it will head if it were to develop are not worth much in my opinion. As always we need a consolidated core that the models can initialize.

again Gator, you do not. The models are quite capable of producing their own centralized core. Not sure why this myth that there needs to be a center for a global model to be of value keeps being spread here

[wxman57]

One think I notice is that the 12Z GFS initializes the low-level vorticity over 250nm east of where the weak mid-level spin can be seen on satellite (east of 35W). That's in the clear air between the two disturbances. If the GFS doesn't know precisely where it's starting from, it may be a bit off in projecting where it may go.

The first disturbance appears to be encountering too much dry air and subsidence. Convection is about zero now. The second wave's convection has weakened considerably today, too. But it does appear quite symmetrical on satellite. Outflow looks impressive. Shear doesn't appear to be an issue with the 2nd disturbance closer to Africa.

Here's a current satellite image of the region. Note that the GFS is developing an area 250nm east of the first disturbance and dissipating the one closer to Africa. I think that may be backwards, though neither has a great chance of developing.

[Ed Mahmoud]

WxMan57 or Derek-

What do you think of the video scenario- shear and SAL too much for now, but an upper low pinching off near Florida provides an area of low shear and upward motion North of the Greater Antilles for one of the waves to develop in?

[wxman57]

WxMan57 or Derek-

What do you think of the video scenario- shear and SAL too much for now, but an upper low pinching off near Florida provides an area of low shear and upward motion North of the Greater Antilles for one of the waves to develop in?

Looking at the GFS forecast for 200mb winds off the east coast as the GFS's "storm" moves through the region north of the DR to 300-500 miles east of Cape Hatteras is for S-SW winds 40-90 kts. Not exactly favorable flow off the east coast in 7-10 days. And that's according to the 12Z GFS. The 12Z Euro is weaker with the east U.S. trof and thus weaker with the southerly winds aloft off the East Coast next week.

[cycloneye]

The 12z EURO has a weak low moving just north of the Leewards / PR and then tracks north of the Bahamas.

12z ECMWF

[wxman57]

The 12z EURO has a weak low moving just north of the Leewards / PR and then tracks north of the Bahamas.

12z ECMWF

Almost imperceptibly weak for the ECMWF, which may not be a bad forecast...

[gatorcane]

The 12z EURO has a weak low moving just north of the Leewards / PR and then tracks north of the Bahamas.

12z ECMWF

Almost imperceptibly weak for the ECMWF, which may not be a bad forecast...

12Z NOGAPS and CMC have totally lost this system. Looks like the GFS is alone again but even it keeps the system as a strong wave with vigorous low at most.

[jinftl]

Systems rolling off the coast of Africa in mid July aren't typically going to develop...just too early for that in the season. But what we are seeing...and this is a difference from prior weeks....is that the train of disturbances seems to be getting going. In other words, the season is evolving as one would expect.

[hurricanetrack]

Systems rolling off the coast of Africa in mid July aren't typically going to develop...just too early for that in the season. But what we are seeing...and this is a difference from prior weeks....is that the train of disturbances seems to be getting going. In other words, the season is evolving as one would expect.

This makes the most sense to me of anything right now. Very well put.