99L a threat to develop; damage from Typhoon Megi still largely unknown
Heavy thunderstorm activity has increased and grown more organized this morning over the southwestern Caribbean between Honduras and the Cayman Islands, in association with a tropical disturbance (Invest 99L). The storm is bringing heavy rain to the Cayman Islands; two inches has fallen so far this morning at Savannah on Grand Cayman Island. Recent satellite imagery shows that 99L has some rotation, and the winds on the northeast coast of Honduras at Puerto Lempira have shifted to the west-northwest, implying that 99L may be developing a surface circulation. Wind shear is a moderate 10 - 20 knots, which is low enough to allow some slow development. Water vapor satellite loops reveal that the atmosphere in the Western Caribbean is moist enough to support development, and the waters beneath are plenty warm, at 29°C. The latest SHIPS model forecast predicts that wind shear over the Western Caribbean will mostly remain in the moderate range, 10 - 20 knots, for the remainder of the week. The current north-northwest motion of 99L should continue until Wednesday, when a strong ridge of high pressure is forecast to build in, forcing 99L to the south or west. However, steering currents will be weak Wednesday through Friday, making it difficult to predict where 99L may wander to. The only models that develop 99L are the GFDL and HWRF. The GFDL model predicts that 99L will spend enough time over water to develop into a hurricane, and brings the storm to the coast of Mexico's Yucatan Peninsula on Sunday morning. The HWRF model has 99L making landfall over Honduras late this week, before the storm has a chance to develop into a hurricane. NHC is giving 99L a 40% chance of developing into a tropical depression by Thursday. I believe the odds are higher, near 60%. The Hurricane Hunters are on call to investigate 99L this afternoon.
Figure 1. Morning satellite image of Invest 99L.
Damage from Super Typhoon Megi still largely unknown
The power is still out and communications are down over the majority of the northern portion of the Philippines' Luzon Island blasted by Typhoon Megi yesterday, so the extent of the destruction wrought by the great storm is still largely unknown. Preliminary news reports indicate that at least 10 people died, and the northern Philippine province of Isabela suffered severe damage. Megi hit Luzon on Monday morning at 3:30 UTC as a Category 5 super typhoon with sustained winds of 165 mph and a central pressure of 914 mb. Baguio near the west coast of northern Luzon received 7.72" of rain from the storm, and many mountainous regions likely received over a foot of rain.
Figure 2. Rainfall rates in excess of 1 inch per hour (orange colors) were observed by the polar-orbiting F-18 satellite in association with Megi at 00:40 UTC October 19, 2010. Image credit: Navy Research Lab, Monterey.
Passage over Luzon Island destroyed Megi's eyewall and inner core region, and the storm compensated by expanding and intensifying the portions of its circulation that were over water. Now that its center is back over water in the South China Sea, Megi has re-developed its inner core and has built a formidable new eyewall. At the same time, Megi has been able to maintain its larger size, and is now a much larger typhoon than when it hit the Philippines. This is similar to what happened to Hurricane Ike in 2008 when it passed over Cuba, and helped give Ike a very destructive storm surge when it came ashore over Texas. Wind shear is a low 5 - 10 knots over Megi, and the waters of the South China sea have a very high total heat content to great depth, so Megi should be able to intensify into a very dangerous Category 4 storm by Thursday. The larger size of Megi means that it will be able to deliver a significant storm surge in excess of ten feet to the coast of China of Friday or Saturday, when the storm is expected to make landfall near Hong Kong. As the storm approaches the coast on Friday, wind shear is expected to rise to the moderate or high range, and the total heat content of the ocean will drop significantly, so some weakening is to be expected. Still, Megi will probably hit China as a major Category 3 typhoon,bringing a significant storm surge, high winds, and widespread torrential rains that will likely make this a multi-billion dollar disaster for China.
"Daily Downpour" airing this afternoon
Our live Internet radio show, "Daily Downpour", will be airing today at 4pm EDT. The call in number is 415-983-2634, or you can post a question to broadcast@wunderground.com. You can tune in at http://www.wunderground.com/wxradio/wubroadcast.h tml, and I'll be discussing the latest info on Invest 99L with hosts Shaun Tanner and Tim Roche.
Jeff Masters
Reader Comments
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Actually it is dry air. As 99L moistens his environment along with the upward MJO pulse later this week, into next week, 99L will blossom nicely!!!
In other words, shear should not be a factor right now
yea dry air is a bigger issue for this than shear is right now
model Error Trend 24hr Error 48hr Error 72hr Error Day 4 Error Day 5 Error
HWRF DECREASING 60.2 85.1 -1 -1 -1
GFDL DECREASING 96.1 96.7 -1 -1 -1
MM5E INCREASING 114.1 193.4 -1 -1 -1
MM5B DECREASING 114.4 178.7 -1 -1 -1
BAMD DECREASING 146.2 219.4 -1 -1 -1
LBAR DECREASING 146.5 163.4 -1 -1 -1
KHRM CONSTANT 170 335.7 -1 -1 -1
Paula contended with worse.
well we will see what it does but that cloud movement beginning just south of Cuba stretching through the straits and into the atlantic is not outflow. not a chance..There is no doubt the system is seriously "right heavy" and I think in the end thats because of shear...we are all entitled to an opinion
I agree
1008.6 mb
They found 1008.5, but that's splitting hairs.
That's been the issue, to me. Plenty of winds, but no real consolidated area of low pressure. Low pressure area still appears to be quite broad.
That is also over 100 miles away from the center fix. 99L probably down to 1008 or 1007 mbs now with convection starting to consolidate over the center.
I do not see any data from the aircraft on TA. Are they still flying ??
That's what I would expect too, but HH just can't find it. 1008.5mb has been the lowest.
again i beg to differ. the initial creation of this storm will be noted for the broad low pressure it has had to work with. when that much low pressure forms and there are pockets of deeper lows there is a competition of sorts when the thing pulls itself together. i think that could be an inhibiting factor for the creation of large storms (many small low pressure pockets in initial formation vying for stronger influence) but the fact that this thing even with that adversity has now pulled itself together into a low level closed circulation things are going to change, and probably quickly.
i have examined many different loops and models and i still can't find the dry air and wind shear you are referencing. for the most part the deep pocket of wind shear that was over the gulf has moved out over the atlantic and the pocket in front of the low trough now over so-cal is not nearly as strong with its westerlies. but as far as a) dry air, and b) wind shear i don't see what you are saying. i would be curious to know what model or map you are extrapolating your data from. here are links to the models i am looking at--
shear tendency
Link
gulf w.v. loop
Link
99L w.v. loop
Link
also, based on the fact that we now have a low level closed circulation i would bet on the chance of major convection springing up all over the place now. at least i would tend to believe there will be a considerable increase in convection now that the circulation has finally wound up in and out, as compared to what this system has looked like over the past few days. i just think it took days to organize the various low pressure pockets into one closed circulation, but by virtue of the fact that it has successfully done that very thing i would tend to favor formation now at this point.
Yes, found 1008.5 about 20min ago at about 17.3N/83.3W.
Try this.
The "see all of this type" drop-down box page is not working.
Try the 21:04Z here
Mostly W and WSW.
Sorry, yes, see corrected post.
Based on HH, it still appears to be a very broad area of low pressure.
And, unfortunately, they are going to leave soon.
No doubt we will see a big convective blow up once the HH has cleared the area LOL
i agree with those model runs for what they are really saying. there are influences on all 4 sides of this development that are going to hold it in place or send it in loop-de-loops.
Correction, have left already. Surprised they didn't issue one last vortex.
LOL. Murphy's Law.
Aircraft climbing out. No new message probably means none warranted based upon fairly static surface data. 99L has work to do tonight it seems.
I think early Wednesday morning should see an upgrade by NHC.
It appears they're done for this flight; they've finished their final delta, and are on their way home. They found lots of TD (and even some TS) force sustained winds at low flight levels; I have little doubt this will be classified as TD19 this evening, if not TS Richard...so long as that convection at the center increases, or at the very least doesn't fade.
URNT12 KNHC 192149
VORTEX DATA MESSAGE AL992010
A. 19/21:15:30Z
B. 17 deg 27 min N
083 deg 26 min W
C. NA
D. 15 kt
E. 141 deg 23 nm
F. 197 deg 14 kt
G. 139 deg 34 nm
H. EXTRAP 1008 mb
I. 23 C / 306 m
J. 23 C / 307 m
K. 22 C / NA
L. NA
M. NA
N. 134 / 1
O. 0.02 / 5 nm
P. AF303 01IIA INVEST OB 19
MAX FL WIND 26 KT NE QUAD 19:50:50Z
MAX OUTBOUND FL WIND 26 KT NW QUAD 21:26:30Z
SLP EXTRAP FROM BELOW 1500 FT
MAX OUTBOUND SFC WIND 27 KT NW QUAD 21:25:30Z
;
Removed as redundant.
Transmitted: 19th day of the month at 21:49Z
Aircraft: Air Force Aircraft (Last 3 digits of the tail number are 303)
Mission Purpose: Investigate eight suspect area (flight in the North Atlantic basin)
Mission Number: 1
Observation Number: 19
A. Time of Center Fix: 19th day of the month at 21:15:30Z
B. Center Fix Coordinates: 17°27'N 83°26'W (17.45N 83.4333W)
B. Center Fix Location: 186 miles (299 km) to the SW (226°) from George Town, Cayman Islands (GBR).
C. Minimum Height at Standard Level: Not Available
D. Estimated (by SFMR or visually) Maximum Surface Wind: 15kts (~ 17.3mph)
E. Location of the Estimated Maximum Surface Wind: 23 nautical miles (26 statute miles) to the SE (141°) of center fix
F. Maximum Flight Level Wind Inbound: From 197° at 14kts (From the SSW at ~ 16.1mph)
G. Location of Maximum Flight Level Wind Inbound: 34 nautical miles (39 statute miles) to the SE (139°) of center fix
H. Minimum Sea Level Pressure: 1008mb (29.77 inHg) - Extrapolated
I. Maximum Flight Level Temp & Pressure Altitude Outside Eye: 23°C (73°F) at a pressure alt. of 306m (1,004ft)
J. Maximum Flight Level Temp & Pressure Altitude Inside Eye: 23°C (73°F) at a pressure alt. of 307m (1,007ft)
K. Dewpoint Temp (collected at same location as temp inside eye): 22°C (72°F)
K. Sea Surface Temp (collected at same location as temp inside eye): Not Available
L. Eye Character: Not Available
M. Eye Shape: Not Available
N. Fix Determined By: Penetration, Wind and Pressure
N. Fix Level: 1,500 feet
O. Navigation Fix Accuracy: 0.02 nautical miles
O. Meteorological Accuracy: 5 nautical miles
Remarks Section:
Maximum Flight Level Wind: 26kts (~ 29.9mph) in the northeast quadrant at 19:50:50Z
Maximum Flight Level Wind Outbound: 26kts (~ 29.9mph) in the northwest quadrant at 21:26:30Z
Sea Level Pressure Extrapolation From: Below 1,500 feet
Maximum Surface (likely estimated by SFMR) Wind Outbound: 27kts (~ 31.1mph) in the northwest quadrant at 21:25:30Z
got some work to do
Viewing: 501 - 551
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