Tropical Tidbits from the Tundra 

Quoting JGreco:
So just to be sure, no threat from Lee for the Western Florida Panhandle region right?

Not impossible, but in my opinion more unlikely at this point.

From the NHC 2pm TWO:

A LARGE AREA OF DISORGANIZED CLOUDINESS AND SHOWERS OVER THE
NORTHWESTERN CARIBBEAN SEA...THE EASTERN GULF OF MEXICO...AND THE
ADJACENT LAND AREAS IS ASSOCIATED WITH A TROPICAL WAVE. THIS
SYSTEM IS EXPECTED TO MOVE GENERALLY WEST-NORTHWESTWARD AT 10 TO 15
MPH. ALTHOUGH UPPER-LEVEL WINDS ARE NOT FAVORABLE FOR SIGNIFICANT
DEVELOPMENT DURING THE NEXT DAY OR TWO...THERE IS SOME POTENTIAL
FOR TROPICAL OR SUBTROPICAL CYCLONE DEVELOPMENT OVER THE CENTRAL OR
WESTERN GULF OF MEXICO IN A FEW DAYS. THIS SYSTEM HAS A MEDIUM
CHANCE...30 PERCENT...OF BECOMING A TROPICAL OR SUBTROPICAL CYCLONE
DURING THE NEXT 48 HOURS.

Oh gee here we go with the possibility for "subtropical" development over the Gulf of Mexico during the first week of September over 31C water. Here's the big, big problem with that statement. There is already an anticyclonic wind flow at 200mb above the tropical wave, which implies warm-core throughout the entire tropospheric column. There is nothing subtropical about it, and if there isn't now, there certainly isn't going to be when it's developing and pumping even more heat into the atmosphere.

Quoting LakeWorthFinn:
When is the best time to visit Alaska? We would love to take a trip up there, but when it's not very cold. You know I'm from Finland and they have wonderful warm summers there, I hate cold and would want to pick the warmest weeks you get.

In the interior our warmest months are June and July, while down south near the coast they are July and August. Anywhere in there would be in the middle of our summer season. It's not as short as some believe lol. Here in the interior we hit 70s in May and we keep those 70s until early September. Down in the southern part of the state and along the coastline, 70s are rarer, though our largest city, Anchorage, gets 70s fairly often during the summer. That's darn hot for me, but I think it's just about warm enough for you lol.

We have Invest 93L as low pressure develops northwest of the Yucatan Channel:

AL, 93, 2011083118, , BEST, 0, 240N, 860W, 25, 0, DB,

Quoting AtHomeInTX:
One more question? On the EURO 850 wind model, do they use knots or mph? I may have missed where it said? Just trying to find out how much wind it's showing. Thanks if ya have the time. :)

It depends on who's giving the data and what units they chose in their computer program for processing the data. If you're talking about Ryan Maue's ECMWF 850mb wind plots, then his scale is in knots.

A decent chunk of the 12z ECMWF ensemble members (purple/pink colors) show Katia approaching the northern Bahamas in 10 days, illustrating how the potential threat to the U.S. isn't over yet given the overall pattern, but a miss seems a little bit more likely for now.

Quoting TomTaylor:
Hey AtHome

I'm not levi, but I've seen you post the euro model runs lately on the blog from the ECMWF site itself, so I am assuming you are talking about this type of image




In this case, it is showing winds for meters per second. 1 Meter per Second (m/s) is equal to about 2.2 Miles per Hour (MPH). So in other words, 1 m/s = 2.2 mph, 40 m/s = 90 mph, 20 m/s = 45 mph.

I forgot that she might be referring to that one. Thanks. I've seen Maue's maps posted far more often on the blogs, so my mind immediately jumped to that map.

Quoting FLGatorCaneNut:
Levi.... thanks for the update...

Question...... Katia and the beginings of Hurricane Andrew in "92 are almost in the same position. I remember how forcaster were saying not to worry that it was headed to the fish grave yard...... as they did not forsee the high moving in as it did.... and we all know what happened after that.......

What are the chances that a high builds in and pushes this further west as the high seems to be moving back and forth alot this season....

Thanks

Well tracks like Andrew and Dora in 1964 can and do happen. Here, a straight west track into the gulf like Andrew is pretty unlikely given that the ridge will still be hanging out near Texas, with a weakness in the ridge near the eastern seaboard. Could Katia get close enough to threaten the east coast? Sure - it's still on the table. I'm leaning more towards unlikely right now, but that doesn't mean it can't happen, for the reasons that I talked about in Monday's video.

Quoting TomTaylor:
Levi, do you know of any good weather/meteorology books or textbooks you could recommend me?

Thanks in advance

Well honestly the only really good, college-level textbook that I have is called "Meteorology Today" by C. Donald Ahrens. I've had it since I was 11, eight years ago, but it's been through several new editions so the latest edition should be up to date.

The NHC is worried...


000
ABNT20 KNHC 312341
TWOAT

TROPICAL WEATHER OUTLOOK
NWS NATIONAL HURRICANE CENTER MIAMI FL
800 PM EDT WED AUG 31 2011

FOR THE NORTH ATLANTIC...CARIBBEAN SEA AND THE GULF OF MEXICO...

THE NATIONAL HURRICANE CENTER IS ISSUING ADVISORIES ON TROPICAL
STORM KATIA...LOCATED ABOUT 1285 MILES EAST OF THE LEEWARD ISLANDS.

A LARGE AREA OF DISORGANIZED CLOUDINESS AND THUNDERSTORMS OVER THE
SOUTHEASTERN GULF OF MEXICO IS ASSOCIATED WITH A TROUGH OF LOW
PRESSURE. UPPER-LEVEL WINDS ARE CURRENTLY UNFAVORABLE FOR
DEVELOPMENT...BUT ARE FORECAST TO BECOME MORE CONDUCIVE ON
THURSDAY...AND THIS SYSTEM COULD BECOME A TROPICAL DEPRESSION
DURING THE NEXT DAY OR SO. THIS SYSTEM HAS A HIGH CHANCE...60
PERCENT...OF BECOMING A TROPICAL CYCLONE DURING THE NEXT 48 HOURS
AS IT MOVES SLOWLY NORTHWESTWARD. INTERESTS ALONG THE ENTIRE
NORTHERN GULF OF MEXICO COAST SHOULD MONITOR THE PROGRESS OF THIS
DISTURBANCE.

ELSEWHERE...TROPICAL CYCLONE FORMATION IS NOT EXPECTED DURING THE
NEXT 48 HOURS.

$$
FORECASTER BROWN

We have Hurricane Katia:

AL, 12, 2011090100, , BEST, 0, 148N, 436W, 65, 987, HU,

Katia looks like a chickling still in its egg, or a gerbil sleeping, or a shrimp. Whatever it is, it's a sign of steady strengthening.

Quoting BrockBerlin:
Levi could you explain to me the reasons why the multi-decadal cycles in hurricane activity occur? Is there any reason why every 20-30 years wind shear (which if I remember right is linked to an enhanced West African monsoon) seems to decrease basin-wide and SST's increase slightly.

I think I have a decent idea of "what" the multi-decadal cycle is, but I am confused why it occurs and what would trigger it every several decades?

We don't know. They are one of the mysteries of the climate that we don't fully understand. We don't even fully understand what governs ENSO yet, and that is the shorter-term manifestation of the Pacific multidecadal signal. To figure out what causes these cycles would be a huge breakthrough in our understanding of the Earth's climate.