Tuesday, August 29, 2017

Harvey and The September Cool Down

1:45PM Tuesday update... the data continues to shift Harvey's shift to the east.  As I have been saying, it's all about the track.  At this time, I still think eastern Arkansas will have the highest chance for rain, but much lesser chances further west.  A few inches still seem possible towards the Mississippi River.  With a track further east, it also diminishes the tornado threat over eastern Arkansas.  Remember, there are still uncertainties with the forecast, BUT the trend is our friend!

With each model run, Arkansas looks a little better!  Remember, it all depends on the track.  We keep saying that, but when it comes to tropical systems like this, it's very true.  It's surrounding and east of the center of low pressure which usually experiences the highest rain amounts and the threat for short-lived/weak tornadoes.  At this time, it appears Harvey will track through southeastern and eastern Arkansas bringing the worst of the weather there with much lesser amounts further west and east.
I know this is NOT good news for the farmers in eastern Arkansas.  Again, I don't claim to know much about agriculture, but heavy rain amounts are probably not good as you get closer to harvest.  All we can hope for is a more eastward shift in the track.

Also, the system appears to be speeding up on the models!  That's also good news.  Rainfall amounts could be limited due to the decreased time it spends in Arkansas.  

What about tornadoes?  That's always a worry with any tropical feature.  That threat will be across southeastern and eastern Arkansas Wednesday into Thursday.  At this time, we're not expecting an outbreak.  If there are any tornadoes, typically they rapidly show up on radar and rapidly diminish.  The favored area again is east of the track.  Another reason why that's so important.

Now onto the VERY long range!  We're continuing to wind summer down with below average temperatures and it will carry into September.  Little Rock will not hit 100° this summer making the first time since 2014 and the 56th summer on record it has not happened.  As a matter of fact, later next week, the models show the strongest trough in a long time digging into the central and eastern United States.  This would deliver a potent shot of cool air.  Don't get too excited just yet.  Remember, long range forecasts are not the best (beyond 7 days).  If it does materialize, we'll call it the "pumpkin spice cold front".  Yes, I just said that and went there.

This is the morning track from the National Hurricane Center.  It barely moves Harvey into Arkansas.  This more eastern shift is better news for the state.  It shifts much of the heavy rain/tornado threat further east.  HOWEVER, this can still change and I would watch this for eastern Arkansas very carefully.  Heavy rain still very possible near that track!
Very low risk for severe weather near the track Wednesday.  Again, low tornado threat.
Very low severe risk Thursday as Harvey begins to lift north and east.
Euro total rainfall amounts.  This is a model and not a forecast.  Look at the drastic decrease further north and west.
The weather prediction center is going close to 9'' eastern Arkansas.  Again, this depends on the track and this is within the realm of possibilities.  Look at that decrease in amounts west and north.
The Euro in 228 hours shows (Thursday Sept 7th), shows a strong trough digging into the central United States.  This is at 500mb.  There's a ridge west and therefore a trough east.  It's in the long range, so don't get too excited just yet.
The NOAA 6-10 day outlook shows a good chance temperatures will be below average.
In the 8-14 day outlook, there's a good chance temperatures will be below average too.  This is the time period of the trough so there's some confidence in this happening.  Stay tuned!

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