Browsing: Uncategorized

Why the uncertainty in the turn?

Ok, it's very simple:  The turn is 5 days out.  Mathematically speaking, you can't accurately forecast 5 days out.  But, there is a small bit of information missing:  The steering current that is supposed to cause the turn is characterized as a "small wave." The question plaguing me is will this "small wave" be strong enough to allow a Cat 4 or 5 storm rotate on its axis?  It's 5 days out.  You can't know.

So, here's the deal:  The storm, as all storms do, wants to turn north, but there is a bulk of air that is forcing it to head west.  This bulk of air isn't supposed to let up until the 5th day allowing Irma to turn.  However.... 5 days is a long time in weather forecasting.

[Continue reading...]

{ Add a Comment }

2017 Sep 4 - Irma Yuck - Jogged SW

Weather Underground models

OK.  This does concern me.  But, I stand firm, that it is still too early to work ourselves up.  However, while you are eating your hamburgers and hot dogs, it might not be too bad of a deal if you struck up a conversation about where you want to spend a few days in a couple of weeks.... maybe.

Irma is still more than 5 days out.  Projects loose accuracy quickly after the 3rd day.

Of note, in the discussion, NOAA is projecting that the storm will not only maintain, but increase its strength.  If there forecast of strengthening is wrong, then at best it will maintain.  Neither is good and I will be watching, with fervor, for a forecast change.

2017 Irma 5-day Projection
5-day projection from NOAA

What follows is the forecast discussion copied from NOAA's website. Keep in mind that NOAA is the sole generator of data for Atlantic storms. Everyone else, takes NOAA's data and interprets it. This includes the newscasters, me, your local government entities and NWS. Tropical data is NOAA's responsibility. Getting it to the public is everyone else's.

WTNT41 KNHC 040854

Hurricane Irma Discussion Number 20
NWS National Hurricane Center Miami FL AL112017
500 AM AST Mon Sep 04 2017

Irma's signature in infrared satellite images has been improving
over the past few hours. An eye has appeared and is warming, and
the central dense overcast has become more symmetric. Although the
satellite presentation is better than when a NOAA plane
investigated Irma last evening, the initial intensity will be held
at 100 kt for now. Another NOAA P3 aircraft is just now beginning
to sample the hurricane and should provide an updated intensity
estimate during the next few hours.

A strong, stationary mid-tropospheric high centered over the central
Atlantic is forcing Irma on a west-southwestward course, and the
initial motion estimate remains 255/12 kt. Irma will begin
rounding the southwestern edge of the high soon, which will allow
the hurricane to turn westward later today and then west-
northwestward in 36-48 hours. Down the road, a large mid-latitude
trough is expected to dig southward over the eastern United States
during the next 72 hours, but the global models have been trending
toward quickly lifting the trough out over New England and eastern
Canada on days 4 and 5, with the subtropical ridge building westward
toward Florida. As a result, it's becoming increasingly likely that
Irma would maintain a west-northwestward heading on days 3 through
5, and the track guidance shifted significantly westward on this
cycle during that period. Remarkably, the track models are very
tightly clustered through day 5, which increases the confidence in
the westward shift of the latest NHC forecast.

All environmental factors suggest that Irma will at least maintain
its intensity for the entire 5-day forecast period, if not
strengthen gradually. Oceanic heat content values increase along
Irma's forecast path, mid-level moisture will be more abundant, and
vertical shear appears to be generally low. As a result, the NHC
intensity forecast continues to call for gradual intensification
through at least 72 hours, with a possibility for some slight
weakening by days 4 and 5 (but still as a major hurricane). As with
any major hurricane, Irma's intensity may fluctuate around these
forecast intensities, but the overall trend is for a gradual
increase of the maximum winds, assuming Irma's core does not move
over any of the islands in the Greater Antilles.

Users are reminded to not focus on the exact forecast track since
strong winds and heavy rainfall extend well away from the center.
In addition, average NHC track errors are about 175 and 225 statute
miles at days 4 and 5, respectively.

1. Irma is expected to affect the northeastern Leeward Islands
within a couple of days as a major hurricane, accompanied by
dangerous wind, storm surge, and rainfall impacts, along with rough
surf and rip currents. Hurricane watches are in effect for
portions of the Leeward Islands, and additional hurricane or
tropical storm watches or warnings will likely be issued later
today. Residents in these areas should monitor the progress of Irma
and listen to advice given by officials.

2. Irma is expected to remain a dangerous major hurricane through
the upcoming week and could directly affect the British and U.S.
Virgin Islands, Puerto Rico, Hispaniola, the Turks and Caicos, the
Bahamas, and Cuba. Residents in all of these areas should monitor
the progress of Irma and listen to advice given by officials.
Tropical storm or hurricane watches will likely be issued for the
British and U.S. Virgin Islands and Puerto Rico later today.
[Continue reading...]

{ Add a Comment }

Why Not To Stress Over Irma, Yet

Historical Tracking Map of 2017 Atlantic Storm Irma
Historical Tracking Map of 2017 Atlantic Storm Irma

First thing is first:  Irma is huge, and if it gets into the hot Gulf of Mexico, and if it targets close to us, then it will be a major threat.... However, this is why I don't think it is appropriate to stress about Irma at this time.

  1.  Storms of this size require a lot of energy to maintain composure over time.  This means that there is a high probability that before it even gets to the Gulf of Mexico that it will "implode" and collapse on itself.   In this case, we have waves of moisture to deal with, but no destructive winds.
  2. The track.   Below, you have a graph of the current track of Irma and the archived track of the beginning of Harvey.  Irma is projected to pass north of Cuba.  Harvey, well to the south. Traditionally, storms that pass north of Cuba do not pose a significant threat to us.
  3. Cuba.  If the track is adjusted and the storm passes a little further south, Cuba has mountains that destroy storms.  Politically, Cuba may or may not be a foe.  Meteorologically speaking, Cuba is always our friend.
  4. Time.  This storm is far away.  If it were to make a beeline to us, it could take more than 2 weeks to get to us.  Projections are only fairly accurate for 3 days.  They are grossly accurate for 5 days.  Anything beyond 5 days is pure speculation.  By the attached graph, you can see that in 5 days, it won't even be touching Cuba.

When should I begin to stress? [Continue reading...]

{ 1 Comment }

%d bloggers like this: