Tropical Depression Fifteen forms in the Caribbean
Tropical Depression Fifteen is here, and is destined to become Tropical Storm Matthew by late this afternoon or this evening. An Air Force hurricane hunter aircraft left the storm near 2pm EDT this afternoon, and on their final pass through the strong northeast quadrant of the storm, found a substantial area of surface winds of 40 - 45 mph with their SFMR instrument. Top flight level winds at 500 feet were 48 mph. These winds support upgrading TD 15 to Tropical Storm Matthew. Satellite loops show that TD 15's heavy thunderstorm activity continues to increase in intensity and areal coverage, with several respectable low-level spiral bands in evidence. There is some dry air to the northwest of TD 15, but it is currently not significantly affecting development.
Figure 1. TD 15 at 11:50am EDT 9/23/10, as seen by NASA's Terra satellite.
Forecast for TD 15
An upper-level high pressure system lies to the west of TD 15, near the coast of Nicaragua. The clockwise flow of air around this high will bring a moderate 10 - 20 knots of wind shear over TD 15 today and Friday. There is some dry continental air lying to the northwest of TD 15, and this shear may be able to drive dry air into the storm, slowing intensification and keeping TD 15 below hurricane strength through Saturday morning. By Saturday afternoon, TD 15 will move more underneath this upper-level high, causing the shear to decline. The SHIPS model forecasts that shear will fall to the low range, 5 - 10 knots, Saturday through Monday. This drop in shear should allow for intensification of TD 15 into a hurricane, if the center stays more than 50 miles offshore.
The future track and intensity of TD 15 depends critically upon the storm's interaction with land over the coming days. If TD 15 misses making landfall in Nicaragua and Honduras, and instead skirts the north coast of Honduras, the storm is likely to intensify into a hurricane by Sunday, as indicated in the official NHC forecast. However, if TD 15 spends significant time over or barely offshore of Honduras, the storm will likely stay below hurricane strength. TD 15 is being forced just north of due west by a strong ridge of high pressure. This ridge will keep the storm moving at 15 mph through Saturday. On Sunday, a trough of low pressure diving southwards over the Eastern U.S. will weaken the steering currents over the Western Caribbean and cause TD 15 to slow and turn more to the north. TD 15 will begin a period of slow and erratic movement on Sunday that may last many days, as the storm wanders in the Western Caribbean and over Belize, Honduras, and Mexico's Yucatan Peninsula. If the center of TD 15 spends significant time over water, the storm could easily develop into powerful and dangerous Hurricane Matthew. If the center remains mostly over land, TD 15 will still generate extremely heavy rains over Central America, but remain below hurricane strength. By late next week, the trough of low pressure over the Eastern U.S. may lift out, allowing a ridge of high pressure to build in and force TD 15 westwards across the Yucatan Peninsula and into the Gulf of Mexico's Bay of Campeche. Alternatively, the trough of low pressure over the Eastern U.S. may amplify, drawing TD 15 northwards across Western Cuba and into Florida. A complicating factor may be the development of a new tropical depression in the Central Caribbean 6 - 8 days from now, as predicted by both the GFS and NOGAPS models with their latest 12Z (8am EDT) runs. The uncertainties in the long-range fate of TD 15 are high, and depend strongly on slight variations in its track that determine how much time the storm spends over land. One thing that is virtually certain is that TD 15 will generate very heavy rains over Nicaragua, Honduras, Belize, and Mexico's Yucatan Peninsula Friday through Tuesday that will cause dangerous flooding rains and life-threatening mudslides.
Tropical Depression Lisa
Tropical Depression Lisa continues to churn the waters of the far Eastern Atlantic. By Saturday night, upper level winds out of the west are expected to increase, bringing high wind shear of 20 - 45 knots over Lisa. The high shear may be capable of destroying the storm by early next week. It appears unlikely that Lisa will affect any land areas.
Elsewhere in the tropics
The remnants of Hurricane Julia are still spinning over the far Eastern Atlantic, and are generating some sporadic heavy thunderstorm to the north of the center of circulation. Julia's remains are being given a 10% chance of re-developing by NHC.
Hurricane Karl's moisture causing flooding in Minnesota, Wisconsin
A plume of very moist air associated with what was Hurricane Karl last week has surged northwards over the Central U.S. over the past two days. This moisture is now being lifted over a warm front draped over Minnesota and Wisconsin, and has generated flooding rains in excess of six inches in southern Minnesota this afternoon. Flood warnings and flood watches are posted for a wide swath of the upper Midwest today, including most of southern Minnesota, northern Wisconsin, and Michigan's Upper Peninsula. These types of rain events are called Predecessor Rain Events (PREs), because they typically precede the actual arrival of the rain shield of a tropical storm.
Figure 2. Radar estimated rainfall over Minnesota.
Next post
I'll have an update on TD 15 Friday morning.
Jeff Masters
Neighbors help a driver to move his vehicle from the flood waters
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 | 53 | 54 | 55 | 56 | 57 | 58 — Blog Index
the front was much stronger with wilma
I'm thinking the track will be further north than Wilma by a fair margin.
yes and the system could slow down a bit more than expected as a stronger system will feel upper level winds, and not as much the surface steering winds
Nope not at all. My folks are in Rockford. I'm down here on the river south of Montgomery now. Ivan got it. Almost every tree in the yard. Crushed everything homeowners didn't cover.
Nice.
As Matthew's track, not liking the prolonged spell over land. Good for the folks after it, not so good for the folks under it.
That place on Earth has seen plenty rains already this year.
And this still isn't a Wilma - that didn't touch Nicaragua and not much of Honduras. This will.
wishcasting Panama City Again aint you
I thought they had a hurricane at Talladega twice a year anyway. Someday they'll figure out how to put a restrictor plate right over the eye of the hurricane and all this tropical forecasting will be for nothing.
Afraid this could be a rain nightmare!
Dega Baby!!....we do not need no Halloween Hurricanes!!
Looks like a twin forming, perhaps?
As long as he stays away from me - I'm in a bad mood! ;) Nitey, nite all!
moving north of due west though, I guess some mid level shear snuck into the circulation
How can i sleep with this thing bombing so much???
LOL no
More like Tampa.
Sounds well enough.....although as I recall Tampa is subject to severe flooding with a properly angled major
Good morning....Yes maam it is!!
hey nobody say TAMPA, don't even think it (LOL) - I just want waves w/no consequences - Tampa would be creamed - specially surge wise
Most experts think Florida will be hit.Keep safe
you talkin' 'bout me ????- LOL
Actually - I'm SRQ (down the road some)...can't imagine a 'cane in Tampa -- Floods bad w/just a T-storm
Lol! Me too!
Location: 14.3°N 79.8°W
Max sustained: 50 mph
Moving: W at 16 mph
Min pressure: 1000 mb
INITIAL 24/0900Z 14.3N 79.8W 45 KT
12HR VT 24/1800Z 14.8N 82.0W 50 KT
24HR VT 25/0600Z 15.5N 84.5W 50 KT...INLAND
36HR VT 25/1800Z 16.2N 86.5W 50 KT...OVER WATER
48HR VT 26/0600Z 16.7N 87.9W 60 KT
72HR VT 27/0600Z 17.5N 89.5W 35 KT...INLAND
96HR VT 28/0600Z 18.5N 89.5W 30 KT...INLAND
120HR VT 29/0600Z 19.5N 89.5W 25 KT...INLAND
No longer a hurricane.
Interesting.
THE LATTER PART OF THE INTENSITY FORECAST IS A
COMPROMISE BETWEEN THESE EXTREMES...AND LIKE THE TRACK FORECAST...IT
IS OF LOW CONFIDENCE.
from its previous heading of (9.6degrees west of) WestNorthWest
TS.Mathew's average speed moving between its last 2 reported positions was ~11.3mph(~18.2km/h)
TropicalDepression15
23Sep 06pmGMT - - 13.9n76.2w - - 35mph - - -1007mb - - NHC.Adv.#1
TD.15 becomes TS.Mathew
23Sep 09pmGMT - - 14.0n76.9w - - 40mph - - - 1006mb - - #2
24Sep 12amGMT - - 14.2n77.7w - - 40mph - - - 1005mb - - #2A
24Sep 03amGMT - - 14.0n78.4w - - 45mph - - - 1005mb - - #3
24Sep 06amGMT - - 14.2n79.3w - - 40mph - - - 1005mb - - #3A
24Sep 09amGMT - - 14.3n79.8w - - 50mph - - - 1000mb - - #4
Copy&paste 13.9n76.2w, 14.0n76.9w-14.2n77.7w, 14.2n77.7w-14.0n78.4w, 14.0n78.4w-14.2n79.3w, 14.2n79.3w-14.3n79.8w, pnd, trb, nbw, vqs, 14.3n79.8w-14.96n83.23w into the GreatCircleMapper for a look at the last 12^hours.
Using straightline projection upon the speed&heading averaged
over the 3hours spanning the last two reported positions:
~20hours from now to CaboViejo,Nicaragua
^ The westernmost line-segment is the straightline projection.
Viewing: 2451 - 2501
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 | 53 | 54 | 55 | 56 | 57 | 58 — Blog Index