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Summer 2022 Medium/Long Range Discussion


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The ol' 3 scenario afd from LOT

 

.LONG TERM...
Issued at 213 PM CDT Mon Jul 18 2022

Wednesday through Monday...

Friday onward, ensemble model guidance advertises a pattern shift
toward quasi-zonal flow in the Great Lakes atop a flattening ridge
over the central United States. Such a pattern typically
corresponds to building heat and humidity as well as chances for
episodic clusters of thunderstorms. It`s tough to determine
exactly where the zone of most frequent thunderstorm clusters may
become established at this range which forces lower than average
confidence in the forecast from Friday through the weekend. There
appear to be three possible forecast scenarios, which are listed
below:

* 1). We end up in the heat dome and south of the zone of active
  convection. In this forecast scenario, dangerous heat would
  become a threat particularly on Saturday and Sunday with highs
  in the mid to upper 90s and dew points in the low to mid 70s.
  Such values would support heat index values in the lower 100s
  and wet-bulb globe-temperatures in the mid to upper 80s (e.g.
  both high enough to cause heat-related illnesses for those
  exposed to the heat for prolonged periods of time). An example
  of this scenario is the 12Z ECMWF.

* 2). We find ourselves within the zone of active convection. In
  this forecast scenario, episodic rounds of thunderstorms would
  bring frequent downpours and, based on pattern recognition,
  chances for severe weather. Many hours would still be dry
  between rounds of thunderstorms. Temperatures would be muted and
  tied to the timing of thunderstorm clusters and residual debris
  cloud cover. Conceptually, there should be a southern edge to
  any thunderstorm activity, so even in this scenario parts of our
  southern forecast zones may still end up with dangerous heat.
  An example of this scenario is the 12Z GFS.

* 3). We have a little bit of both; heat and humidity followed by
  thunderstorms in that order. As would be expected with 100+
  individual model runs available every 6 hours, successive rounds
  of ensemble data support this camp. After a steamy Saturday,
  thunderstorm chances would appear to increase overnight into
  Sunday as demonstrated by a the "squint test" applied to 6-hour
  QPF meteograms. An example of this scenario is perhaps the NBM.

Since our gridded database can`t show three scenarios at once, we
are forced to take a "middle of the road" approach that modestly
favors scenario 3. Accordingly, we will advertise highs in the upper
80s to lower 90s and nearly continuous but low (20-40%) chances for
thunderstorms from Friday onward. Big swings in the forecast (e.g.
increasing temperatures and/or chances for thunderstorms, but not
necessarily together) are possible as we head through the week.

Borchardt

 

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The ol' 3 scenario afd from LOT
 
.LONG TERM...Issued at 213 PM CDT Mon Jul 18 2022Wednesday through Monday...Friday onward, ensemble model guidance advertises a pattern shifttoward quasi-zonal flow in the Great Lakes atop a flattening ridgeover the central United States. Such a pattern typicallycorresponds to building heat and humidity as well as chances forepisodic clusters of thunderstorms. It`s tough to determineexactly where the zone of most frequent thunderstorm clusters maybecome established at this range which forces lower than averageconfidence in the forecast from Friday through the weekend. Thereappear to be three possible forecast scenarios, which are listedbelow:* 1). We end up in the heat dome and south of the zone of active convection. In this forecast scenario, dangerous heat would become a threat particularly on Saturday and Sunday with highs in the mid to upper 90s and dew points in the low to mid 70s. Such values would support heat index values in the lower 100s and wet-bulb globe-temperatures in the mid to upper 80s (e.g. both high enough to cause heat-related illnesses for those exposed to the heat for prolonged periods of time). An example of this scenario is the 12Z ECMWF.* 2). We find ourselves within the zone of active convection. In this forecast scenario, episodic rounds of thunderstorms would bring frequent downpours and, based on pattern recognition, chances for severe weather. Many hours would still be dry between rounds of thunderstorms. Temperatures would be muted and tied to the timing of thunderstorm clusters and residual debris cloud cover. Conceptually, there should be a southern edge to any thunderstorm activity, so even in this scenario parts of our southern forecast zones may still end up with dangerous heat. An example of this scenario is the 12Z GFS.* 3). We have a little bit of both; heat and humidity followed by thunderstorms in that order. As would be expected with 100+ individual model runs available every 6 hours, successive rounds of ensemble data support this camp. After a steamy Saturday, thunderstorm chances would appear to increase overnight into Sunday as demonstrated by a the "squint test" applied to 6-hour QPF meteograms. An example of this scenario is perhaps the NBM.Since our gridded database can`t show three scenarios at once, weare forced to take a "middle of the road" approach that modestlyfavors scenario 3. Accordingly, we will advertise highs in the upper80s to lower 90s and nearly continuous but low (20-40%) chances forthunderstorms from Friday onward. Big swings in the forecast (e.g.increasing temperatures and/or chances for thunderstorms, but notnecessarily together) are possible as we head through the week.Borchardt

 


No shot at option #1, which isn’t fully what the 12z Euro shows anyway.
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The long range GFS is just crazy, but we have seen that modeled super heat not really materialize yet so a lot of skepticism is warranted.  Good reason to think it will get warmer in August, but there's a big difference between getting warmer and what the GFS is advertising.

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The long range GFS is just crazy, but we have seen that modeled super heat not really materialize yet so a lot of skepticism is warranted.  Good reason to think it will get warmer in August, but there's a big difference between getting warmer and what the GFS is advertising.

I haven’t been able to find any information on if there had been any sort of upgrade conducted to the OP GFS heading into the summer.

In any case, between it being too amped with ridging in the extended and the unrealistic super deep mixing it consistently has, it’s toss worthy on the reg now.
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11 minutes ago, cyclone77 said:

Meh, prob more 95-97 for MLI lol.  Best heat event of the year by far was in mid May for the DVN cwa.  

Relative to average, yeah, May wins.  But seems like actual temps could surpass what happened in May *if* it lives up to potential.

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^Pretty embarrassing actually.  Can't even blame it on some loony run that is 300 hrs out.  That map is a week out, when you'd expect a reasonably accurate portrayal.

I’m still not sure what NCEP did to it, but whatever it is, it needs to be reversed.
  • Haha 1
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