Hurricane Epsilon continues to be intriguing for its uniqueness, but
otherwise a dull footnote. It is unique in that it is a rare
December hurricane (there have been several December tropical storms,
but only a handful of hurricanes). It is also unique in that it has
held it's own, and even strengthened at times, over 68-72F waters,
and few forecasters have even bother to attempt to explain why.
Frankly, I'm not even certain... we see this from time to time with
former-extratropical cyclones, likely due to cooler upper level
temperatures (I've often talked about this and research done at MIT
which shows that the often-ballyhooed 80F threshold is true only in
the standard tropical environment, but cold epper level temps can
lower that 80F threshold). But Epsilon has long since lost any
extratropical remnant characteristics. May it still be cold aloft?
Sure. And that may, indeed, be what's driving it. But it would
be purely a guess to say this definitively. Otherwise, the story
on Epsilon is bland and unchanged...
Current Conditions: Most recent satellite images as of Monday PM
are finally beginning to show some decay. While surprisingly deep
convection does remain in some quadrants, the entire southeastern
quadrant of the eyewall has decayed and opened up. In fact, at 00Z
the SAB Dvorak estimate just dipped down enough to bring Epsilon to
a 55kt tropical storm. Given the gradations in the Dvorak technique,
I'd say Epsilon remains very close to hurricane strength, but MAY be
just below now... at about 60kts. As for motion, the satellite
data and fixes indicate an almost due southeast motion now... at
about 125 or 130 degrees at 7kts.
Model Discussion: With the current motion, clearly the more
significant "looping" solutions appear to be on track. The models
have, generally, responded to this. However, even though the larger
loop moves Epsilon over warmer waters, the developing hostile upper
level winds cause most of the models to still wipe the storm out
quickly. For example, the NOGAPS, which had emphasized an eastward
motion, now (00Z Tue run) has Epsilon looping S and even SWward, but,
nonetheless, dissipates the storm by 72hrs (Thu). The 18Z GFS is
actually extremely similar, showing a reasonably tight loop with
dissipation by Thu afternoon. Almost amazingly, given the complexity
of the situation, the 12Z ECMWF is in near perfect agreement... a
modest curl and Thursday dissipation. The 12Z GFDL is *nearly* the
same, except that it gets tripped up at the end... it's just a bit
slower on the dissipation and, thus, allows Epsilon to rebound as
conditions improve. The 12Z UKMET was not readily available, but
the 00Z run mathced the other models well... showing a moderate loop
(though the UK was a bit broader than some) with dissipation by
Thursday morning.
My Thinking: Once again, difficult to say much. I'm not sure how I
could possibly diverge from the models much at all. I would have
been tempted to hold Epsilon together beyond Thursday, given its
resiliency to date. But with Dvorak estimates now drifting down and
the southeastern eyewall collapsing, I'm not so certain that it'll
continue to be so resilient. So, I'll go for dissipation on
Thursday. As for the track, while the situation is complex, the
model agreement is strong and the loop is already begun. So, again,
I'm just following the models on this... a clockwise loop through
dissipation.
-Gary
Additional products and services available!!
Not currently subscribed? Click here for details