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
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If you don't mind me asking, exactly what do you have to do to get ready for a Hurricane on a rig that takes that long? I thought it took that long to get the people off the rig.
Aircraft RECON
Plan of the Day
000
NOUS42 KNHC 231600
WEATHER RECONNAISSANCE FLIGHTS
CARCAH, NATIONAL HURRICANE CENTER, MIAMI, FL.
1200 PM EDT THU 24 SEPTEMBER 2010
SUBJECT: TROPICAL CYCLONE PLAN OF THE DAY (TCPOD)
VALID 25/1100Z TO 26/1100Z SEPTEMBER 2010
TCPOD NUMBER.....10-114
I. ATLANTIC REQUIREMENTS
1. SUSPECT AREA
FLIGHT ONE -- TEAL 70 FLIGHT TWO -- TEAL 71
A. 24/1200,1800Z A. 25/0000,0600Z
B. AFXXX 0215A CYCLONE B. AFXXX 0315A CYCLONE
C. 24/0830Z C. 24/1945Z
D. 14.8N 80.3W D. 15.3N 83.0W
E. 24/1130Z TO 24/1800Z E. 24/2330Z TO 25/0600Z
F. SFC TO 15,000FT F. SFC TO 15,000 FT
2. SUCCEEDING DAY OUTLOOK: CONTINUE 6-HRLY FIXES IF
SYSTEM REMAINS A THREAT.
3. REMARKS:
A.THE NOAA G-IV MAY FLY AN 8 HR RESEARCH MISSION INTO
THE AREA TOMORROW DEPARTING AT 24/1730Z AND
OPERATING 41,000 TO 45,000 FT
B.THE G-V WILL FLY A 7 HR MISSION INTO THIS
AREA DEPARTING 24/1200Z. OPERATING FL 380-430.
Maybe at the 5:00 PM update tomorrow.
The info is still there. Just have to dig for it these days. The people posting the best information in here are pretty good at avoiding getting wrapped-up in the melodrama.
Not sure if that is specific to the 18Z run, or that it may be the graphics package. You can see similar on the nested runs for Lisa at all of the hours, not just 18Z. It may also be feedback as you are thinking, not sure.
He is just getting to the end of the ridge..There will be some lag adn I am very curious to see exactly how much. But again the next few hours will tell a lot.
Thanks, and nice to see you Pat!
this thing has way more fuel than igor, and conditions are more favorable for development than with igor at the moment.. so yea I agree, I expect it to develop rapidly!
TS Matthew Statistical/Simple Models (CLIPER,BAMs,LBAR,other Statistical Models)
Dynamic Models (More sophisticated models)
Looks like he is going to flex him muscles a little bit. The overall structure looks so much different then 24hrs ago.
I 2nd that!
RGB Image
it has been organizing itself the entire day today at the surface to suck up an ample amount of energy from the carribean which is why it didn't look so organized convectively, yet still became a tropical storm..
what you're saying is true, but I still expect it to develop rather rapidly tonight
I don't study this stuff days on end all the time but I don't recall seeing winds analysis this consistent, on all layers, in a long time. Looks odd to me.
Prob of RI for 25 kt RI threshold= 46% is 3.7 times the sample mean(12.6%)
Prob of RI for 30 kt RI threshold= 23% is 2.9 times the sample mean( 8.1%)
Prob of RI for 35 kt RI threshold= 12% is 2.5 times the sample mean( 4.8%)
Prob of RI for 40 kt RI threshold= 7% is 2.0 times the sample mean( 3.4%)
Its looking pretty potent... and symmetrical.
Thats allot of rainfall headed to C. America.
Matthew is already consolidating at a decent rate, Compare it to what is was like 12 hours ago.
Those are a very nice set of storms.
Viewing: 1301 - 1351
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