Naby

http://www.crownweather.com/?page_id=4557

Thursday, June 21, 2012 6:04 am

by Rob Lightbown

This morning’s analysis shows an area of low pressure now located very near the Yucatan Channel. Satellite imagery showed scattered deeper convection across the entire length of the Yucatan Channel and into western Cuba. The strongest vorticity at the lower-levels were very close to this low pressure system. Wind shear values this morning over this low pressure system are right around 20 to 30 knots, which is barely favorable for any sort of development. Much stronger wind shear on the order of 50 knots currently exists over the Gulf of Mexico, however, these wind shear values are expected to decrease and become more favorable by this weekend.

The overall forecast guidance this morning shows many different possible scenarios for this system to both develop and track.

The latest NAM model guidance forecasts a track towards the northern Gulf of Mexico once we get into Saturday and Sunday. The Canadian model is the strongest in intensity, by far, of all of the latest models. It forecasts a track towards the northern Gulf of Mexico as a probable hurricane by Sunday and then forecasts a turn towards the west and an eventual landfall somewhere between Brownsville and Corpus Christi, Texas on Wednesday of next week as a very strong hurricane.

The UKMET model also forecasts a track towards south Texas as early as Monday.

The latest European model guidance forecasts a track towards the northeastern Gulf of Mexico by Monday and then shows a track across northern Florida as a hurricane right around next Thursday before tracking rapidly northeastward into the Gulf of Maine and Bay of Fundy by next Saturday.

The GFS model guidance also is forecasting the eastern track option, however, its solution is suspect to me as it spits out multiple low pressure centers and doesn’t pull together like I think it will.

The GFS ensemble guidance seems to agree with the UKMET and Canadian models and go the option of south Texas. It should be pointed out that many times the guidance overestimate the strength of upper level troughs and I think this is the case here. Bottom line is that I think this is Texas bound rather than a track across Florida.

Given that, here is my thinking as of this morning: (see picture below)

I want to end by saying that a lot can change with the forecast track of what is likely to be Debby. Right now, based on the data I am looking at, I think this is Texas bound, however, there is a chance that the trough will end up being strong enough to pull it northeastward across northern Florida like the European model is forecasting. Needless to say, it is a very fluid situation and I am keeping very close tabs on it.

Attached Thumbnails

 

Mike aka FishWerks

http://www.wunderground.com/tropical..._ensmodel.html

Looks like a system to watch closely.

Don White

extended forecast discussion
nws hydrometeorological prediction center camp springs md
330 pm edt fri jun 22 2012

valid 12z mon jun 25 2012 - 12z fri jun 29 2012

the developing omega-block centered near greenland favors slow
movement of an expanding upper high over the plains...and upper
lows near the pacific northwest and over the northeast through the
upcoming medium range period. Model agreement is quite good
through days 3-4/mon-tue...before disagreement increases
particularly over the northeast pacific which then causes
differences in how and when the low near the pacific northwest
will eject eastward. model uncertainty remains very high with low
pressure near the yucatan peninsula...with the ukmet farthest west
through the entire period...followed by the ecmwf...canadian...and
finally the gfs which is on the eastern side of the guidance.
Orientation of the upper high over the plains supports west or
even southwestward movement eventually but when that begins is
crucial to its path. For now...will remain consistent with
yesterday's forecast points based on the daily coordination call
with the nhc which resulted in a low remaining near the center of
the gulf through day 7. elsewhere...the preliminary
pressures/fronts were started with the 00z ecmwf before
transitioning toward increasing percentages of the ecmwf ensemble
mean to account for the growing uncertainty with time.

Update...
The morning blend of the 00z ecmwf/12z ecmwf ensemble mean was
updated to a blend of the 00z ecmwf/00z ecmwf ensemble mean. The
forecast still started with a greater weight towards deterministic
ecmwf...transitioning to a greater percentage of the ensemble
mean. This resulted in minimal changes to the original
fronts/pressures graphics. Model guidance remains in good
agreement over the conus early in the medium range period with
setting up an upper ridge over the central u.s. And troughing
along either coast. After day 4...however...ensemble members
begin to show a decent amount of spread with the flattening of
flow over the western half of the country and shifting the trough
over the eastern u.s. Offshore. In general...the ecmwf has been
on the slower side of the spread with ejecting energy
northeastward across the pacific northwest and into canada...while
the gfs has been one of the quickest solutions. The past day of
ecmwf runs have been fairly consistent with this feature...plus it
is supported by the 00z cmc/ukmet...so the forecast leaned towards
the slower ecmwf solution. By day 6-7 the 00z ecmwf is also on
the slower side of model spread with pushing the upper through
over the eastern u.s. Offshore...but the 00z ecmwf ensemble mean
seemed to offer a good middle of the road solution. a great
amount of uncertainty still exists with the development of low
pressure over the gulf of mexico...so no major changes will be
made across the region until after the afternoon nhc/hpc
coordination call.

final...
No significant changes were made for the final issuance of medium
range forecasts. the 12z gfs shifted slower than its 06z run with
the energy ejecting across the pacific northwest days 3-4...which
boosted confidence in using the slower 00z ecmwf solution early in
the forecast period. Over the gulf of mexico...deterministic
models have come into some sort of agreement with strengthening a
surface low over the central gulf and then stair-stepping it
westward towards the texas coast...with the exception of the 12z
gfs which tracks the low northeastward through florida.
However...the large amount of spread in the 00z ensemble members
still indicate a great amount of uncertainty with this system.

weather-wise across the conus...
An amplifying upper ridge will heat things up over the central
u.s....while troughs anchored along the east and west coasts
should keep conditions pleasantly cool during the medium range
period. Depending on the exact track of the low developing in the
gulf of mexico...heavy rainfall could be a threat all along
coastal regions from texas to florida.


James/gerhardt

Naby

Crownweather still thinks it will stall and go to the west but it sounds like we may get some watches and warnings today.

http://www.nwfdailynews.com/news/sys...-currents.html

BananaTom

Shhhhhhhhhh!

This kinda thread is not good.

This section, I believe, is how to survive one, not summon one here.

And never ever say the "H" word!!

Crashcrew

Along with the typical food and water i think now more then ever ammo is going to be a issue. Prolly see some laws comming againts ammo soon>

Crashcrew

the tropics are really heated up but seems most everthing is staying away

hawgfan

the long range gfs puts soon to be Isaac just off the La coast on the 30th, I sure hope not we'll be in orange beach for vac starting the 26th and I really want to surf fish for the whole week.

Catchin Hell

Just in case some are confused... OP posted about TS Debbie. Isaac is the new TS out there and deserves its own thread if someone would like to start one...