Atlantic tropical system update: 2 named systems by morning?

Edit: 12:31 p.m. Eastern, August 15th: They named the Eastern Atlantic storm Erin this morning and reduced the likelihood of development for the Gulf of Mexico disturbance to only 50/50. It still looks like that GoM disturbance will most likely just bring a lot of moisture to the southeast and east.

The last time I was in the Southeast (2008), they had a terrible drought ongoing, but fortunately, that has recovered. Pity these rains couldn’t head west instead:

All it would take is one or two hurricanes making landfall in the Texas coastal area and curving inland to modify and perhaps even erase those colors, but that is very costly, too.

We’ll see how the rest of the season plays out.

*************************

Edit: 6:52 a.m. Eastern, August 15th: No named storms yet, but during the night the NHC upgraded the status of the Eastern Atlantic disturbance to a tropical depression, number 5 of the year. Here is the current, rather technical (see comment and highlighted portions for basic gist, as this amateur sees it), forecast discussion:

000
WTNT45 KNHC 150845
TCDAT5

TROPICAL DEPRESSION FIVE DISCUSSION NUMBER 2
NWS NATIONAL HURRICANE CENTER MIAMI FL AL052013
500 AM AST THU AUG 15 2013

SATELLITE IMAGERY THIS MORNING SUGGESTS THAT TROPICAL DEPRESSION FIVE IS GETTING BETTER ORGANIZED. A CONVECTIVE CLUSTER WITH TOPS COLDER THAN -80C HAS FORMED NEAR AND TO THE WEST OF THE CENTER…AND THERE IS OUTER BANDING IN THE SOUTHEASTERN SEMICIRCLE. SATELLITE INTENSITY ESTIMATES FROM TAFB AND SAB ARE BELOW TROPICAL STORM STRENGTH…SO THE CYCLONE WILL REMAIN A 30-KT DEPRESSION FOR THIS ADVISORY. HOWEVER…THIS INTENSITY COULD BE A LITTLE CONSERVATIVE. [That is, this is approaching tropical storm strength and could become Erin today…Barb]

THE INITIAL MOTION IS 290/14. THE DEPRESSION IS CURRENTLY ON THE SOUTH SIDE OF A LOW/MID-LEVEL RIDGE OVER THE EASTERN ATLANTIC…AND THE TRACK GUIDANCE IS IN GOOD AGREEMENT THAT THIS WILL STEER THE CYCLONE WEST-NORTHWESTWARD FOR THE NEXT 2-3 DAYS. AFTER THAT…THE GUIDANCE DIVERGES. THE GFS…THE GFS ENSEMBLE MEAN…AND THE CANADIAN MODELS SHOW THE SYSTEM TURNING WESTWARD. THE ECMWF…THE UKMET…AND THE GFDL SHOW A WEST-NORTHWESTWARD TO NORTHWESTWARD MOTION…WITH THE CYCLONE MOVING TOWARD A WEAKNESS IN THE RIDGE OVER THE CENTRAL ATLANTIC. OVERALL…THE GUIDANCE ENVELOPE HAS SHOWN A NORTHWARD SHIFT SINCE THE LAST ADVISORY. SINCE THE CYCLONE IS EXPECTED TO WEAKEN AND BE STEERED BY THE LOW-LEVEL FLOW DURING THIS TIME…THE NEW FORECAST TRACK SHOWS A WESTWARD TURN IN BEST AGREEMENT WITH THE GFS. WHILE THE NEW FORECAST TRACK IS A LITTLE NORTH OF THE PREVIOUS TRACK AFTER 48 HR…IT IS WELL TO THE SOUTH OF THE ECMWF…THE UKMET…THE GFDL…AND THE CONSENSUS MODELS.

THE DEPRESSION IS CURRENTLY IN AN ENVIRONMENT OF WARM SEA SURFACE TEMPERATURES AND LIGHT VERTICAL WIND SHEAR. THIS SHOULD ALLOW SOME STRENGTHENING UNTIL THE SYSTEM REACHES COOLER WATERS IN 48 HR OR SO. [Again, possible Erin…Barb] WHILE THE CYCLONE IS FORECAST TO LEAVE THE COOLER WATERS AFTER THAT TIME…THE GFS…ECMWF…AND UKMET ARE IN GOOD AGREEMENT THAT IT SHOULD ENCOUNTER VERY DRY AIR AND WEAKEN…WITH THESE MODELS SHOWING THE SYSTEM DEGENERATING TO A TROPICAL WAVE BY 120 HR. THE NEW INTENSITY FORECAST DOES NOT YET FOLLOW THAT SCENARIO…AS THE SHIPS AND LGEM MODELS SHOW A STEADY-STATE OR STRENGTHENING SYSTEM. INSTEAD…THE FORECAST CALLS FOR A SLOW WEAKENING AS A COMPROMISE BETWEEN THESE EXTREMES.

FORECAST POSITIONS AND MAX WINDS

INIT 15/0900Z 14.4N 25.2W 30 KT 35 MPH
12H 15/1800Z 15.0N 27.2W 35 KT 40 MPH
24H 16/0600Z 15.7N 30.0W 40 KT 45 MPH
36H 16/1800Z 16.4N 32.6W 45 KT 50 MPH
48H 17/0600Z 17.2N 35.0W 50 KT 60 MPH
72H 18/0600Z 18.0N 39.5W 50 KT 60 MPH
96H 19/0600Z 18.0N 43.5W 45 KT 50 MPH
120H 20/0600Z 18.0N 48.5W 40 KT 45 MPH

$$
FORECASTER BEVEN

*************************

I don’t know, but here is what the NHC says:

National Hurricane Center, as of August 14th, evening.

National Hurricane Center, as of August 14th, evening.

000
ABNT20 KNHC 142331
TWOAT

TROPICAL WEATHER OUTLOOK
NWS NATIONAL HURRICANE CENTER MIAMI FL
800 PM EDT WED AUG 14 2013

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

THE LOW PRESSURE SYSTEM IN THE NORTHWESTERN CARIBBEAN SEA IS MOVING TOWARD THE WEST-NORTHWEST AT 10 MPH…AND IS PRODUCING WIND GUSTS TO GALE FORCE IN SQUALLS TO THE EAST OF THE CENTER. ASSOCIATED SHOWER AND THUNDERSTORM ACTIVITY CONTINUES TO SHOW SIGNS OF
ORGANIZATION…AND A TROPICAL DEPRESSION COULD FORM BEFORE THE DISTURBANCE REACHES THE YUCATAN PENINSULA ON THURSDAY. AFTER THAT…THE LOW IS FORECAST TO MOVE INTO THE SOUTHERN GULF OF MEXICO…WHERE UPPER-LEVEL WINDS COULD BECOME A LITTLE LESS FAVORABLE FOR DEVELOPMENT. THIS SYSTEM HAS A HIGH CHANCE…70 PERCENT…OF BECOMING A TROPICAL CYCLONE DURING THE NEXT 48 HOURS…AND A HIGH CHANCE…80 PERCENT…OF BECOMING A TROPICAL
CYCLONE DURING THE NEXT 5 DAYS. REGARDLESS OF WHETHER OR NOT A TROPICAL CYCLONE FORMS…HEAVY RAINS AND GUSTY WINDS ARE FORECAST TO SPREAD OVER THE YUCATAN PENINSULA…WESTERN CUBA…AND BELIZE DURING THE NEXT DAY OR TWO…AND INTERESTS IN THESE AREAS SHOULD MONITOR THE PROGRESS OF THIS DISTURBANCE.

SHOWERS AND THUNDERSTORMS CONTINUE TO ORGANIZE NEAR THE CENTER OF A LOW PRESSURE SYSTEM LOCATED ABOUT A HUNDRED MILES SOUTH-SOUTHEAST OF THE CAPE VERDE ISLANDS…AND A TROPICAL DEPRESSION COULD FORM TONIGHT OR ON THURSDAY. THIS SYSTEM HAS A HIGH CHANCE…80 PERCENT…OF BECOMING A TROPICAL CYCLONE DURING THE NEXT 48 HOURS WHILE IT MOVES WEST-NORTHWESTWARD AT 10 TO 15 MPH. AFTER THAT…THE LOW WILL BE MOVING INTO A LESS FAVORABLE ENVIRONMENT FOR DEVELOPMENT OVER THE CENTRAL TROPICAL ATLANTIC…AND IT HAS A HIGH CHANCE…80 PERCENT…OF BECOMING A TROPICAL CYCLONE DURING THE NEXT 5 DAYS. REGARDLESS OF ADDITIONAL DEVELOPMENT…THE LOW WILL LIKELY BRING SHOWERS AND GUSTY WINDS TO THE SOUTHERN CAPE VERDE ISLANDS TONIGHT AND ON THURSDAY. INTERESTS IN THE CAPE VERDE ISLANDS SHOULD MONITOR THE PROGRESS OF THIS SYSTEM.

&&

FIVE-DAY FORMATION PROBABILITIES ARE EXPERIMENTAL IN 2013. COMMENTS ON THE EXPERIMENTAL FORECASTS CAN BE PROVIDED AT…

WWW.NWS.NOAA.GOV/SURVEY/NWS-SURVEY.PHP?CODE=ETWO

Even if one or both get named, from what I understand of the graphical GFS model (which isn’t much – I’m a rank amateur…always remember that), as of tonight anyway it looks like the disturbance near the Yucatan might briefly intensify a little bit into maybe a depression, but then get disorganized again and just end up spreading a bunch of tropical moisture into Mississippi and Alabama and then on up the Eastern seaboard.

The one in the Eastern Atlantic, it seems to this amateur, at least on tonight’s GFS run, appears more likely to form a system, but it won’t make it across the Atlantic as conditions become unfavorable again (I’m not sure exactly what those conditions might be – cooler waters perhaps, dry air, or even wind shear although that will be less, per my understanding of the graphic, than it was last week).

Even meteorologists have difficulty basing forecasts on the models this early, though. About all that can really be said just now is that – finally – the Atlantic basin seems to be waking up.



Categories: Weather

Tags: , , ,

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s

%d bloggers like this: