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FORECAST ARCHIVE: 5/2/2008
(Non-event)
Forecast: Friday, May 2, 2008
UPDATE #4
UPDATE 11:55am 5/2/08
Just about crunch
time now. The atmosphere is in the process of "reloading" after
all
the morning thunderstorm activity came through and turned everything
over. So far new thunderstorms have yet to redevelop, but it's
looking
like initiation will begin shortly.
Originally
our target was northern Illinois. However, since initiation appears to
be beginning a bit earlier, we may end up heading west into
Iowa.
We're still debating whether to head there and catch the early stuff,
or wait until the storms cross into Illinois where there's better
moisture.
For now we'll wait and see how things develop over the next hour
or two.
Here's
a map showing the current situation. You can see the clearing
behind
the earlier rains. The surface low is down to 992mb, and is still
deepening a bit actually. Earlier in the week the models had it
weakening by now. So that's good. This is keeping the
surface winds
fairly backed ahead of it. Some very good vorticity advection at
500mb
is approaching from the southwest. Wind shear is definitely not a
problem.
UPDATE #3:UPDATE 5/1/08 10:50pm
Things looking on track for tomorrow's chase. The latest
forecast model runs have come in with little change.
I
think my overall biggest concern right now is all the morning
thunderstorm activity getting out of the area in time to let the
atmosphere recharge. Hopefully that won't be an issue. If
it's not,
then we should have a pretty good day tomorrow.
Storms
will likely start firing by noon near the Mississippi river, and then
push east across Illinois during the afternoon. My gut feeling is
we'll end up out near LaSalle. There is a very good road network
in
northern and central Illinois so we should be in good shape if a change
in direction is needed.
Below is a quick map of our basic target area.
UPDATE #2:
UPDATE 4/30/08 10:10pm…
Things are still looking on track for a chase
Friday. It now looks like the surface low
will be in northeast Iowa
One thing that we’re lacking that we had last
Friday is a strong wind field at the surface and just above it. Last week we had very strong southerly winds
(gusting over 40mph at times) as the surface low strengthened. With this storm the lower 2,000 feet will have
a much lower velocity wind field. Helicity
is projected to be weaker with this storm too. Keep
in mind these are based on model forecasts and it’s still a few days
away.
On the plus side we will have nice directional
wind shear. An approaching mid-level speed
max should maximize that even further. Rotating
supercell thunderstorms will definitely be a good possibility.
Still a bit early, but at this point
our chase target may very well be pretty damn close to home. Kind of like last week lol.
It sure is looking like we won’t have to go too far to find the
storms we’re looking for. We’ll fine tune
all this later tomorrow or early Friday…
UPDATE #1:
After really speeding the system up yesterday, most of the models have slowed things back up again. Now keeping the surface low in northeast Iowa at 7pm Friday evening. Yesterday a few of the models had it way into Wisconsin by that time.
Unlike Thursday, moisture should certainly not be as much of an issue. What may be an issue is the usual worry about the previous night's convection/debris. I'm not all that thrilled with the surface low slowly filling in during the afternoon either, but it's nothing too extreme. I'd much rather have a deepening surface low however instead of a filling one. Sometimes the models can fill a surface low too quickly. Hopefully that's the case here lol.
With all that being said, it looks like the surface and 850mb winds should stay fairly backed through the day. Overhead, decent 500mb winds will be veered enough for respectable directional shear. Should be some impressive lift with the very impressive fanning out of the mid and upper level wind field.
Still a few questions left to be answered, but this is still two days out.
May 2nd chase prospects....
After really speeding the system up yesterday, most of the models have slowed things back up again. Now keeping the surface low in northeast Iowa at 7pm Friday evening. Yesterday a few of the models had it way into Wisconsin by that time.
Unlike Thursday, moisture should certainly not be as much of an issue. What may be an issue is the usual worry about the previous night's convection/debris. I'm not all that thrilled with the surface low slowly filling in during the afternoon either, but it's nothing too extreme. I'd much rather have a deepening surface low however instead of a filling one. Sometimes the models can fill a surface low too quickly. Hopefully that's the case here lol.
With all that being said, it looks like the surface and 850mb winds should stay fairly backed through the day. Overhead, decent 500mb winds will be veered enough for respectable directional shear. Should be some impressive lift with the very impressive fanning out of the mid and upper level wind field.
Still a few questions left to be answered, but this is still two days out.
May 2nd chase prospects....
Friday May 2nd
has been looking pretty good for chasing here in the Mississippi NAM
If anything, this may
increase the chances for a Thursday chase (May 1st). It had looked like Thursday’s chase was way
too far away considering our work obligations (and these horrific gas
prices lol). If this faster trend holds
true, then we may end up heading out Thursday instead.
An added note… We’re a bit concerned about the powerful cold
front that has scoured the Gulf of Mexico
of deep moisture the last two days. This
is a bit unusual for this time of year, as most polar fronts “wash out”
before entering the deeper portions of the GOM. Anyway,
because of this cold front, deeper moisture return may be a bit more
delayed than what the models are currently forecasting.
Obviously
this could have a very big impact on instability and the quality of the
thunderstorms with Thursday and Friday’s system…
18z GFS:
18z GFS:
-Joel 042908 9:30pm