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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Thats exactly what I was thinking.
Typically when we refer to closed low, its at the surface.
...FINALLY THE FIRST NAMED STORM OF THE 2009 SEASON HAS ARRIVE...
A closed low at the surface that extends upwards to 700mb.
NATIONAL WEATHER SERVICE HONOLULU HI
334 PM HST SAT AUG 8 2009
...FELICIA TO BRING HEAVY RAINS TO PORTIONS OF THE STATE...
HIZ012>028-091445-
/O.NEW.PHFO.FF.A.0003.090810T1600Z-090812T0400Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
MOLOKAI WINDWARD-MOLOKAI LEEWARD-LANAI MAKAI-LANAI MAUKA-
KAHOOLAWE-MAUI WINDWARD WEST-MAUI LEEWARD WEST-
MAUI CENTRAL VALLEY-WINDWARD HALEAKALA-LEEWARD HALEAKALA-
HALEAKALA SUMMIT-KONA-SOUTH BIG ISLAND-BIG ISLAND NORTH AND EAST-
KOHALA-BIG ISLAND INTERIOR-BIG ISLAND SUMMITS-
334 PM HST SAT AUG 8 2009
...FLASH FLOOD WATCH IN EFFECT FROM MONDAY MORNING THROUGH
TUESDAY AFTERNOON...
THE NATIONAL WEATHER SERVICE IN HONOLULU HAS ISSUED A
* FLASH FLOOD WATCH FOR KAHOOLAWE...LANAI...MAUI...MOLOKAI AND
THE BIG ISLAND
* FROM MONDAY MORNING THROUGH TUESDAY AFTERNOON.
* ABUNDANT MOISTURE ASSOCIATED WITH FELICIA IS EXPECTED TO PRODUCE
EXTREMELY HEAVY RAINFALL WITH THE POTENTIAL FOR WIDESPREAD FLASH
FLOODING INCREASING ON MONDAY AND CONTINUING INTO TUESDAY.
PRECAUTIONARY/PREPAREDNESS ACTIONS...
PEOPLE IN FLOOD PRONE AREAS NEED TO PREPARE NOW FOR THE POSSIBILITY
OF TORRENTIAL RAINS ASSOCIATED WITH FELICIA. ROCK AND MUDSLIDES ARE
ALSO POSSIBLE ONCE THE HEAVY RAIN BEGINS.
IT IS IMPORTANT TO REMEMBER THAT HEAVY...FLOODING RAINFALL COULD
OCCUR EVEN WELL AWAY FROM THE CENTER OF FELICIA.
A FLASH FLOOD WATCH MEANS THAT CONDITIONS MAY DEVELOP THAT LEAD
TO FLASH FLOODING. FLASH FLOODING IS A VERY DANGEROUS SITUATION.
YOU SHOULD MONITOR LATER FORECASTS AND BE PREPARED TO TAKE ACTION
SHOULD FLASH FLOOD WARNINGS BE ISSUED.
&&
$$
BURKE/R BALLARD
I'll need therapy if this fizzles.
Thats what I was thinking...especially if Avila gets to write it.
Wow that would be one heck of a feat if it can pull that off after only a day on water i remember waiting here for days for a storm to get a closed low....really quite impressive
LOL. That new feature is the best shot yet for development.
Hi Pottery, hope you made it through the rain okay.
You think alot don't you...
Ohhh a big sunspot..
oh wait... thats a piece of grime on my screen..
Apparently.
more easy orange!!
Of course! Attention is focused on the tropics like it should...and not other irrelevant stuff.
LINK
How about a:
Thank you! That is really cool how that one storm pinwheeled near the coast as the wave was moving west. This is really looking promising, and i can say that after seeing that image. I just put it in my latest blog entry.
--------------------------------------------------------------------------------
Float Areas
Atlantic
East and Central Pacific
West Pacific
CURRENT TIME
(based on your computer's time):
been a long hard coupla months. For all ya'll do, if this is gonna be the first, kudos to all of you. I'd pop open some champagne when they name this, and share it with every one of you.
You have bad taste...
FXCA62 TJSJ 090117 AAA
AFDSJU
AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE SAN JUAN PR
917 PM AST SAT AUG 8 2009
.UPDATE...SHOWERS ARE SMALL AND SCATTERED IN THE SOUTHEAST OF THE
FORECAST AREA AND ONLY A FEW ARE MOVING THROUGH PUERTO RICO AND
THE U.S. VIRGIN ISLANDS AT THIS TIME. THE NAM SUGGESTS THAT SHOWERS
WILL INCREASE OVERNIGHT ON THE WINDWARD COAST OF PUERTO RICO AND
THE IN THE U.S. VIRGIN ISLANDS AS CURRENT FORECAST INDICATES.
LATEST GFS SUGGESTS THAT THE NEXT WAVE WILL ARRIVE ON TUESDAY
AFTER 8 AM AST AND HAVE MADE SOME ADJUSTMENTS IN THE POPS FOR
THIS. BOTH NAM AND GFS MODELS HAVE THE TROUGH IN THIS WAVE MOVING
AT 13 KNOTS SO TIMING DOES NOT APPEAR TO BE THE PRINCIPAL
DIFFERENCE. NEVERTHELESS...TUESDAY AFTERNOON MAY BE A LITTLE
WETTER IN THE EASTERN HALF OF PUERTO RICO AND THE ISLANDS EAST OF
THERE THAN ORIGINALLY EXPECTED. MODELS SHOW WINDS AND SEAS
INCREASING DURING A WIND SURGE AFTER A WAVE PASSAGE WEDNESDAY
NIGHT. WINDS AT 850 MB REACH 30 TO 35 KNOTS THURSDAY NIGHT IN THE
GFS SOLUTION.
&&
.DISCUSSION...SAHARAN DUST CONTINUES ACROSS THE AREA...BUT THERE
IS A LITTLE BREAK IN THE SATELLITE IMAGERY BEFORE ANOTHER EPISODE
ARRIVE. SUSPECT SKIES WILL REMAIN A LITTLE HAZY...BUT WILL NOT
HIGHLIGHT THIS IN THE ZONES. THE MODELS FROM THE NRL SUGGEST THAT
DUST WILL ABATE AFTER THE 12TH OF AUGUST.
Possibly, but I think they'll wait until 8.
Hey....
I win.
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