Potentially dangerous 92L steadily developing; Igor nears hurricane strength
A tropical disturbance (92L) over the Eastern Caribbean, a few hundred miles south of Puerto Rico, is steadily organizing and appears likely to develop into a tropical depression by tonight or Sunday morning. Satellite loops show an impressive and expanding region of heavy thunderstorms, with good spiral banding and respectable upper-level outflow on all sides. Long range radar out of Puerto Rico shows that heavy rains are now affecting that island, but there is no rotation to the radar echoes evident. However, the rain bands are becoming more intense and more organized. San Juan, Puerto Rico reported a heavy rain squall at 8:44 am this morning, and radar estimates suggest two inches of rain fell in this squall just southeast of San Juan. Wind shear over 92L is low, 5 - 10 knots. The waters beneath are at near-record warmth, 30°C, and these warm waters extend to great depth. Water vapor satellite loops show a large area of dry air lies to the north and west of 92L, and this dry air could interfere with development at times over the next few days.
Figure 1. Morning satellite image of 92L.
Track forecast for 92L
The disturbance is moving west-northwest at 11 mph, and steering currents favor a continuation of this motion for the next three days. Model support for development is scattered. The GFS and NOGAPS models do not develop 92L. The GFDL and ECMWF models predict development, with a track taking 92L into Mexico's Yucatan Peninsula on Wednesday. The HWRF model has a more northwesterly track, taking 92L over the Dominican Republic, Haiti, and Cuba, but this model has been trending too far north in its tracks. I expect 92L will follow a path south of the islands, bringing it near or just south of Jamaica on Monday, then into the Yucatan Peninsula on Wednesday. On this track, the southern Dominican Republic can expect heavy rains of 3 - 6 inches tonight through Monday morning; southern Haiti can expect similar rains Sunday through Monday, and Jamaica and the Cayman Islands can expect heavier rains of 4 - 8 inches Monday and Tuesday. Eastern Cuba will probably escape 92L's heaviest rains in this scenario (Figure 2.)
Intensity forecast for 92L
I can't find any reason to doubt this will be a tropical storm by Sunday or Monday, and potentially a Category 1 or 2 hurricane by Wednesday, if 92L avoids passage over Hispaniola and Cuba. The SHIPS model predicts wind shear will remain low, 5 - 10 knots, through the period, and makes 92L a Category 1 hurricane by Monday night. Water temperatures are certainly warm enough to support development. The main detriment to intensification is likely to be dry air, and 92L could wrap in some of the dry air to its northwest at times, slowing down development. The first Air Force Hurricane Hunter mission into 92L is scheduled for Sunday afternoon, but there will be a research mission by the National Center for Atmospheric Research G-V jet today that will give us valuable information on 92L's large scale environment and potential for development.
Figure 2. Forecast rain amounts from 92L from the 2am EDT Saturday run of the GFDL model. This model predicts most of 92L's heaviest rains will miss Haiti, but will affect Jamaica, the Cayman Islands, and the Yucatan Peninsula. Image credit: Morris Bender, NOAA/GFDL.
Igor
Tropical Storm Igor is very close to hurricane strength, and appears destined to become a large and powerful major hurricane over the Central Atlantic in the days to come. Wind shear is moderate, 15 - 20 knots, waters are warm, 28°C, and Igor has moistened its environment enough to keep the dry air of the Saharan Air Layer (SAL) at bay. Igor will track west under the influence of a strong ridge of high pressure for the next three days, then turn more to the west-northwest in response to the steering influence of a broad trough of low pressure moving across the Western Atlantic on Tuesday and Wednesday. This should allow Igor to pass several hundred miles to the northeast of the Lesser Antilles. In the longer range, Igor may be a threat to Bermuda, and has a slight chance of making landfall on the U.S. East Coast or Canada. Climatology shows that about 10% of all tropical cyclones that have existed at Igor's current position have gone on to hit the U.S. East Coast; these odds are about 10% for Bermuda and 5% for Canada. The forecast steering pattern for the coming two weeks from the GFS model shows a continuation of the pattern we've seen all hurricane season, with regular strong troughs of low pressure moving off the U.S. East Coast. This pattern favors Igor eventually recurving out to sea without affecting any land areas. The odds of Igor hitting land in the U.S. or Canada are probably close to their climatological 10% and 5% probabilities, respectively.
Elsewhere in the tropics
A new tropical wave (Invest 93L) emerged from the coast of Africa yesterday, and is already showing signs of organization. Most of the models predict 93L will develop into a tropical depression 2 - 4 days from now, and NHC is giving 93L a 30% chance of developing by Monday.
Next post
This may be my only post today; I'll have a new post Sunday morning.
Jeff Masters
Reader Comments
Page: 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | 16 | 17 | 18 | 19 | 20 | 21 | 22 | 23 | 24 | 25 | 26 | 27 | 28 | 29 | 30 | 31 | 32 | 33 | 34 | 35 | 36 | 37 | 38 | 39 | 40 | 41 | 42 | 43 | 44 | 45 | 46 | 47 | 48 | 49 | 50 | 51 | 52 — Blog Index
We're not looking for Cape Verde systems to hit the US of A like a lot of you trolls think.
We're looking for home-grown storms in the Caribbean and Gulf to hit the US of A.
I don't get it. The thing just rolled off Africa...it needs a chance to prove its self in open water for a while. If it's truly a depression the NHC will classify it...I personally would like to see persistence for another 12 hours or so. We have all seen beautiful waves/lows fall off the African coast and turn into nothing. I think the NHC is doing the right thing and when it's time to classify, they will.
Yes but total atmospheric moisture can be quite high still even when water vapor satellite shows dry air.
Also, the air mass can be quite dry when the water vapor shows moisture.
For example, over Florida a few days back, the water vapor showed very dry air over the peninsula. But this was very deceiving, because the PWAT was still reading 2.17 inches due to very deep low level moisture, and sure enough, storms popped everywhere with daytime heating as usual. We even received 2.13 inches in 25 minutes from a very heavy storm, which is common this time of year in central Florida.
But still, my point being is water vapor satellite does not necessarily confirm whether or not a an atmosphere is over all moist or dry.
However you're right that my mistake about water vapor satellite only indicating upper level conditions is not true. It also does indicate what is going on in the mid-levels.
Good.
Getting real tired of the trolls though.
How about you, Storm?
Considering its past of having a surface circulation, we know it has the capability. Within 48 hours this should be a TC. But I welcome a difference in opinion. Would be too boring without it lol
No, the video he post today, the Japanese model and I think he say the gfs.
Igor has not shrunk, he just sucked in some dry air, the circulation of Igor remains the same size as yesterday as you can view on visible imagery. All that happened was Igor lost some convective growth. But as time passes it will flare back up.
Large tropical cyclones can intensify rapidly too, Wilma was a very large tropical cyclone, and absolutely exploded.
Bermuda ouch.
Good Afternoon Wunder bloggers.
Yeah, not so pumped about what I'm doing now lol, more of what I'm looking forward to. I'm doing all the math and physics first before I do the actual MET classes, so there's nothing pretty or exciting about school yet.
Its just a good feeling to know what lies ahead, and what I can look forward to!
Thanks Levi...
for your tropical tidbit. Sure didn't like the Japanese model you shared with us. Let's tell Japan to stick to making cars... not forecast models. 8^)
Feeding water vapor from the south. Dry air in the north..
SYNOPSIS FOR THE GULF OF MEXICO
1030 AM CDT SAT SEP 11 2010
.SYNOPSIS...TROUGH WILL MOVE W ACROSS THE BAY OF CAMPECHE SUN
THROUGH WED. A COLD FRONT WILL CLIP THE FAR N WATERS LATE SUN
INTO MON. OTHERWISE WEAK HIGH PRES WILL DOMINATE THE REMAINDER
OF THE GULF THROUGH WED.
Hey I was wondering what is a troll for this blog?
thanks you answered my question
we are supposed to have a "cold Front" move thru here, lake charles area on monday, should be a drop in humidity, and wondering if this will nudge the storm northwestward
Have a a few questions
1. Have you ever wished to experience a hurricane?
2. Did your opinion of hurricanes change after you experienced it?
3. What changes did you make after the experience of the hurricane?
there is a spin to the wsw of igor on the visible
Gotcha. I just wanted to stay clear troll classification. Seriously though it is amazing how active this season is compared to earlier this summer. Is this what you have been expecting?
Thanks!
Its good to see there are actually few people on this blog like you still that correct me and actually know what they are talking about. I hate when people immaturely make rude replies to me and don't have a clue about meteorology lol.
I like learning new things, after all that's why I'm going to college now for meteorology. Correction is good, as long as it comes from people who know their stuff!
Viewing: 451 - 501
Page: 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | 16 | 17 | 18 | 19 | 20 | 21 | 22 | 23 | 24 | 25 | 26 | 27 | 28 | 29 | 30 | 31 | 32 | 33 | 34 | 35 | 36 | 37 | 38 | 39 | 40 | 41 | 42 | 43 | 44 | 45 | 46 | 47 | 48 | 49 | 50 | 51 | 52 — Blog Index