Felicia not weakening; new African wave may develop
Hurricane Felicia has not weakened today, and continues to hold its own in spite of cool sea surface temperatures beneath it. Recent satellite imagery shows that the tops of thunderstorms surrounding the eye have cooled slightly, indicating that the updrafts sustaining the eyewall are maintaining their strength. The appearance of the hurricane has improved some today, with the storm assuming a more symmetric appearance.
Figure 1. Current satellite image of Hurricane Felicia.
Sea surface temperatures (SSTs) under Felicia have now fallen to 24.7°C, well below the 26°C threshold typically needed to sustain a hurricane. SSTs will slowly increase to 26°C by the time the storm reaches Hawaii, though. Wind shear is expected to remain low to moderate, 5 - 15 knots, through Monday morning. By Monday night, shear will rise to 20 knots, and remain above 20 knots thereafter. The higher shear combined with the relatively cool SSTs should mean that Felicia will be rapidly weakening in its final 24 hours before reaching Hawaii. Several of the computer models continue to show that this shear will be high enough to tear Felicia apart before it reaches Hawaii, though it appears to me that Felicia's current strength and annular structure will help it resist the shear enough to allow the storm to hit Hawaii as a tropical depression with 35 mph winds. Regardless, Felicia will bring heavy rain Hawaii beginning on Monday morning, and these rains will have the capability of causing flash floods and mudslides. The Hurricane Hunters are scheduled to make their first low-level investigation of Felicia this afternoon (around 10 am Hawaiian time). The NOAA jet also flies into Felicia today, and will drop a series of dropsondes that will be used to gather data that will be fed into today's 12Z and 00Z computer model runs.
Typhoon Morakot hits Taiwan
Typhoon Morakot hit Taiwan yesterday, battering the island with Category 1 winds and heavy rain. The Taipei airport recorded sustained winds of 56 mph, gusting to 76 mph, at the peak of the storm. Morakot killed 6 on Taiwan and 10 in the Philippines, and is headed towards a final landfall on mainland China as a tropical storm later today. Storm chaser James Reynolds intercepted the storm and posted videos on typhoonfury.com and Youtube. Morakot is still visible today on Taiwan radar.
Figure 2. Visible satellite image of a spinning tropical wave leaving the coast of Africa. The image was taken at 8am EDT 8/8/09.
African tropical wave may develop
A strong tropical wave with a moderate amount of spin is moving off the coast of Africa this morning. The wave is under about 10 - 20 knots of wind shear and has sea surface temperatures beneath it of 27°C. These conditions are probably too marginal to allow development over the next two days. As the wave moves westward away from Africa over the next few days, wind shear should slowly decrease and the SSTs will warm, potentially allowing for some slow development. The UKMET, GFS, and NOGAPS models all indicate the possibility that this will become a tropical depression 3 - 5 days from now. The ECMWF model forecasts that strong easterly winds over the wave will create too much shear to allow development. The wave is well south of the Saharan Air Layer, so dry air and African dust should not interfere over the next 3 - 5 days. I give the wave a medium (30 - 50% chance) of developing into a tropical depression in the next seven days.
I'll have an update on Sunday.
Jeff Masters
Reader Comments
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Persistent deep convection around a LLC/MLC
ECMWF develops the feature
Recognized by the NHC.
0,0,0 all the way!!
Unlike most of the waves to move off Africa this season convection isn't just limited to the ITCZ. There's moderate to strong convection to the west of the wave axis and to the north of the 850-700mb low. This should help to limit the amount of dry air inflow from the SAL to the north. Also of note is a frontal rope feature extending between this wave and the one proceeding it along 15°N. Scattered weak to moderate convection is noted along this feature indicating a moist enough atmosphere for continued convection as it heads south of the Cape Verde Islands.
Looking ahead there are a few concerns for this system, namely being bouts of 20-25kt easterly shear in the 24-60hr time frame which could hinder development. Beyond 72hrs a developing TUTT over the central Atlantic might draw this system to the north but feelings from this forecaster are that this won't be a terribly strong system and might not feel the weakness to the north as much as models are indicating. So barring any rapid intensification between now and then I think this first trough should pass the system by.
One thing to keep in mind is forecast models poor performance in lifting out eastern US troughs too soon and not forecasting them to be as deep as they've become thus far this boreal summer. Day 5 models forecast models indicate the mean eastern US trough axis at ~85°W but also forecast it to be more of a zonal trough. Should this trough be deeper than indicated geopotential heights will be higher over the western Atlantic, possibly pinching off a upper low halfway between the Azores and Puerto Rico instead of a full-latitude trough that would otherwise all but guarantee recurvature.
Very interesting future for this one indeed but early call is a miss of the islands to the north. Although I don't foresee recurvature before 60°W there is enough weakness to the north of the system to draw it north of them.
I am definitely surprised that the NHC is mentioning this already. I would've been a tad more conservative. It must be a damn good wave for them to mention it this early, given that some of the circulation is still overland.
The circulation is over water now
Jeff Masters
Apparently.
TROPICAL WAVE IS ALONG 18W S OF 18N MOVING W NEAR 10 KT. LATEST
INFRARED SATELLITE IMAGERY INDICATES THE WELL DEFINED LOW/MID
LEVEL CYCLONIC CIRCULATION CENTER IS MOVING E OF THE WAVE AXIS
WHICH IS EMBEDDED WITHIN THE MOISTURE MAXIMUM OBSERVED IN TOTAL
PRECIPITABLE WATER IMAGERY. SCATTERED MODERATE/ISOLATED STRONG
CONVECTION IS ASSOCIATED WITH THE LOW/MID LEVEL CIRCULATION
COVERING THE AREA FROM 11N-16N BETWEEN 19W-22W.
You get to compare your thoughts as to what ends up happening then getting to weigh the outside influences and use them to better your odds at getting the next one right.
You may not always be right but it's good to be wrong cause then you can be critical of yourself, which is the best form of criticism.
Learn from mistakes, etc.
I agree. I do not care what track it takes, with this being a slow season im willing to watch anything.
Convection forming on the NE side now.
This wave is not bashful.
Dmax soon?
yep
Yep
DMAX looks to be approaching.
Closest thing I have to a rainbow sat.
Updates every 15 minutes though.
I agree its seems like its fireing up quickly now thats its off the coast
ok link please tia
Its there...click on the blue.
Looks like we will have a very busy August and September; maybe as active as 2004's. I hope not, though, for Florida's sake.
Yep
I stated that quite a few posts ago.
Unlikely, but we'll see what happens.
Put your cursor in the bottom left corner area, hold down te shift key and move your cursor toward the upper right to expand the image. I'm running 6 frames and increasing the speed. Looks good.
Good Morning Tropical Wave !
thanks maybe you guys will like this one dont know if it updates faster tho
Link
That updates every three hours.
img src="
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