2017 Global Model Runs Discussion (Out to day 16)

[TheStormExpert]

Also notice the strong Bermuda High being portrayed by the Euro in it's 6-10 day range. The GFS shows a Bermuda High though it retreats east but that model has been notorious for underestimating ridges as we've seen for years now, take Matthew as the most notable recent example.

[TheStormExpert]

Since there is no thread yet for the potential BoC system I'll just put this here.

 https://twitter.com/RyanMaue/status/892832865997795330

[OntarioEggplant]

Why on earth does the GFS have tropical lows coming off the coast of Western Sahara and Mauritania? That seems very wrong.

[Hammy]

Why on earth does the GFS have tropical lows coming off the coast of Western Sahara and Mauritania? That seems very wrong.

I could be very wrong, but I believe those are associated with the SAL outbreaks--I noticed the same thing last year as well around this time.

[RL3AO]

Why on earth does the GFS have tropical lows coming off the coast of Western Sahara and Mauritania? That seems very wrong.

They're not tropical waves or anything. Just the typical lows that form during summer over a desert region.

[Hammy]

Why on earth does the GFS have tropical lows coming off the coast of Western Sahara and Mauritania? That seems very wrong.

They're not tropical waves or anything. Just the typical lows that form during summer over a desert region.

Are those similar to the southwestern US heat lows then?

[AJC3]

Why on earth does the GFS have tropical lows coming off the coast of Western Sahara and Mauritania? That seems very wrong.

They're not tropical waves or anything. Just the typical lows that form during summer over a desert region.

Are those similar to the southwestern US heat lows then?

That is precisely what that is - the western flank of the Saharan heat low.

[weathaguyry]

Also notice the strong Bermuda High being portrayed by the Euro in it's 6-10 day range. The GFS shows a Bermuda High though it retreats east but that model has been notorious for underestimating ridges as we've seen for years now, take Matthew as the most notable recent example.

The Euro map gives me an uneasy feeling that if something gets going, it may ride west then turn north and ride the east coast, like Irene or Hermine,

[RL3AO]

Are those similar to the southwestern US heat lows then?

Yep. And the low-pressure area over the Tibetan plateau that brings the Asian monsoon.

[Hurricaneman]

Why on earth does the GFS have tropical lows coming off the coast of Western Sahara and Mauritania? That seems very wrong.

They're not tropical waves or anything. Just the typical lows that form during summer over a desert region.

Are those similar to the southwestern US heat lows then?

Exactly as they're in all deserts in the world

[TheStormExpert]

Are those similar to the southwestern US heat lows then?

Yep. And the low-pressure area over the Tibetan plateau that brings the Asian monsoon.

Would those lows also help decrease the SAL and it's outbreaks?

[cycloneye]

 https://twitter.com/RyanMaue/status/892844565324890113

[RL3AO]

Would those lows also help decrease the SAL and it's outbreaks?

I don't really know. I haven't studied much about the conditions that lead to SAL outbreaks. I'd imagine a stronger pressure gradient between the Azores high and Saharan low may increase SAL if anything, but it's only a guess.

[AJC3]

Are those similar to the southwestern US heat lows then?

Yep. And the low-pressure area over the Tibetan plateau that brings the Asian monsoon.

Would those lows also help decrease the SAL and it's outbreaks?

Excellent question. I'm inclined to say "probably", but sort of indirectly.There is a known inverse correlation between West African/Sahel rainfall and the magnitude of SAL outbreaks. And while I'm not an expert in the mechanics of the African Easterly Jet (AEJ), It also stands to reason that there is a correlation between the strength of both the AEJ and the Saharan heat low, and the interplay between the two likely has some impact on Sahel rainfall, and thus SAL outbreaks. This would probably make for some good nighttime reading.

[Hypercane_Kyle]

12z UKMET very vigorous with the African wave.

[Blown Away]

12 Euro has a TS/Cane moving across Atlantic, NE Caribbean, PR, and dies in Hispaniola... Remnants seem to continue WNW, so any deviation N of Hispaniola may bring a system near the SE Bahamas/Cuba/CONUS @Aug 13 - 15th...

[Kingarabian]

Again no BOC/WCaribb system on the GFS.

[Siker]

Again no BOC/WCaribb system on the GFS.

It's coming in now, not as quick to develop as the Euro perhaps and thus weaker before landfall.

[TropicalAnalystwx13]

Yeah, it's there, just later and weaker. GFS is doing some strange things with vorticity in the Caribbean--it weakens the source wave near the Windward Islands before showing a strong vort almost out of nowhere west of Jamaica. The Euro evolution makes more sense.

[RL3AO]

Week 2 North America pattern could be very important (what else is new). Could be a fun one to track.