FV3 CAPE performance example

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Jack Settelmaier, modified 7 Years ago.

FV3 CAPE performance example

Youngling Posts: 18 Join Date: 11/2/12 Recent Posts

I wanted to share visual evidence as to the FV3's superior? performance over the GFS in advertising the May 1 (actually May 1-3 was a busy period) severe weather that occurred centered over north central KS.

SPC Reports (May 1)

Forecast Hour=00 ("Observed")

What I've provided here are FV3 and GFS surface-based CAPE forecasts 216-, 168-, and 120- hours in advance of May 1st--the day of the event. I've also provided the 00-hr forecast as indication of "roughly" the observed CAPE.

What can be seen is how the FV3, in its 216- and 168-hr forecasts, was a) showing much larger CAPE to the south and east (inflow area) of where the multiple tornado reports occurred. b) These forecast values were larger than those "observed." c) Arguably, however, the greater forecast values in the FV3 vs the GFS provided more indication of the upcoming impact event, despite having CAPE values too large.

Forecast Hour=216

Forecast Hour=168

I only show the 120-hr as at that forecast hour and closer in toward the observed time (lower forecast hours), d) both models had basically the same values shown.

Forecast Hour=120

So, did the FV3 "win" this event? Its higher CAPE values certainly would draw more attention to an upcoming event, which in this case DID occur, BUT, might the FV3 be overvigorous in its "energetics?"

Lastly, with regard to possibly being over-energetic, I have included both 384-hr MSLP forecasts from the 00Z May 9th runs of the GFS and FV3, as displayed on the TropicalTidbits website, valid for the Friday heading into the Memorial Day 2018 weekend. Both show a vigorous tropical system in the Gulf. FWIW, other nearby model runs have a similar feature, but at different time projections.

FV3 384-hr Forecast

GFS 384-hr Forecast

Some WFO/SPC reference information at these links:

EF-3, couple of EF-1s on May 1st.

https://www.weather.gov/top/180501_Summary

http://www.spc.noaa.gov/climo/reports/180501_rpts.html

EF-1s on May 2nd.

https://www.weather.gov/eax/may022018

TORs each day.

fv3 gfs cape spc

Mark Klein, modified 7 Years ago.

RE: FV3 CAPE performance example

Youngling Posts: 4 Join Date: 4/15/15 Recent Posts

Hi Jack,

Interesting example and thanks very much for sharing it. What seemed to be the case is that, in general, the FV3's CAPE was mostly higher in the warm sector than the GFS. It'll be interesting to see if that is a systematic difference or not.

Mark

Jack Settelmaier, modified 7 Years ago.

RE: FV3 CAPE performance example

Youngling Posts: 18 Join Date: 11/2/12 Recent Posts

Mark Klein:

Hi Jack,

Interesting example and thanks very much for sharing it. What seemed to be the case is that, in general, the FV3's CAPE was mostly higher in the warm sector than the GFS. It'll be interesting to see if that is a systematic difference or not.

Mark

Thanks Mark.

Looking ahead, and reviewing future out-period forecasts (beyond ~120hrs) as in this 144-hr fcst, valid the evening of the 13th (Sun) it indeed looks like the FV3 prefers to have a "hotter" surface-based CAPE for most time steps. I guess next, one could examine the "input parms" to see which have the same "hot" reflection.

Logan Dawson, modified 7 Years ago.

RE: FV3 CAPE performance example

Youngling Posts: 3 Join Date: 8/16/17 Recent Posts

Hi Jack,

Thanks very much for pointing out this example. I'll be covering the 1 May severe weather event during tomorrow's MEG meeting, though I won't be delving too much into the medium-range guidance. This is certainly an interesting case comparison between the GFS and FV3.

Although the CAPE values appear too high in the FV3 at F216, I'm quite impressed with how spot on the FV3 was with the location of the key surface features (00Z 2 May surface analysis shown for reference).

Note how the FV3 had a much better handle than the GFS with the lows in southeast Canada and southeast Colorado, the associated surface trough/frontal boundary, and the dryline at F216. The following three images are GFS-FV3 comparisons for SLP, 2-m temperature, and 2-m dewpoint valid at 00Z 2 May.

The CAPE values in the warm sector are definitely still something to keep an eye on, but the overall synoptic "success" at F216 is encouraging to see. A quick glance at F168 and F120 suggests the FV3 had a better handle on these features at those leads as well (though it was clearly too fast with the cold front at F168).

Jack Settelmaier, modified 6 Years ago.

Late may tropical system?

Youngling Posts: 18 Join Date: 11/2/12 Recent Posts

When we "last met," discussing the FV3's long-lead-time CAPE performance, I had included a couple of 384-hr forecasts from both the GFS and FV3, valid for 00Z May 25. Both were showing rather monstrous-looking tropical systems in the GOM.

Now, fast forward 192-hrs, and it's comforting to see that, especially the FV3, both models have backed off that forecast, and are generally much more benign.

That said, however, now both the GFS and FV3 show a potentially-impacting tropical latitudes system in their current 240-hr forecasts, valid 48 hours later at 00Z May 27th--Saturday night of Memorial Day weekend. And to see where each model has their low center, I've switched off TT, to use the comparison image generated by EMC.

The FV3 has a 981mb system on the tip of the Yucatan, while the GFS has a 985mb system over FL's space coast.

While, as usual, neither model is likely to be correct at such forecast projections, it is noteworthy that the ECMWF also depicts a 995mb system in the vicinity, just west of Tampa.

In summary, LOTS of bouncing around at long-lead forecast projections, especially with trying to resolve a potential system at tropical latitudes in May, but, of course, always good to keep an eye on. Now on to make a new post of what I really wanted to share....

Steven Zubrick, modified 6 Years ago.

RE: FV3 CAPE performance example

Youngling Posts: 3 Join Date: 9/25/12 Recent Posts

Jack,

(17 May 2018-550PM EDT) - Thanks for providing sample from these ultra-extended forecast periods (384 hr!). We noticed the 240hr 00Z/17 May suite of guidance had "lows" in various locations of the eastern Gulf of Mexico.

It'll be interesting how it turns out. And the 00Z/06Z 17 May FV3 run had some interesting solutions in the extended as well...

Steve Z-SOO/WFO Sterling, VA (LWX)

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