Sunday, June 18, 2017

Chase 2017 is on the horizon

I haven't posted in about 2 years here.  We do the chase trip every other year, and in between it remains dormant.  I'll endeavour to keep these posts going while a) we're gearing up for the trip and b) on the trip.  I can't make any promises, except that I'll try my best.

In the past, leading up to U of M storm chase trips I've done post after post outlining how the models suck at long-range forecasting, especially as it pertains to deep moist convection.  I will sort of do the same thing here, although it won't focus so much on how much they suck as what solution(s) they're converging on.  The reason is that, the farther into the future you go, the more wildly variable solutions can be.  Previous posts have gone way out to the edge of the models' temporal domains, but this one is going to start out in the realm of higher likelihood.

All that said, there's an extra wildcard thrown into the mix for these forecasts: tropical weather. Some model solutions depict tropical weather in the Gulf of Mexico over the next week or so. Tropical depressions are well known as processes that really mess things up in model land.  What this will mean, then, is that there is lower-than-average confidence in the forecasts outlined below.

Here are the various model solutions from the available guidance as of 11:30 PM CDT June 17, 2017 for the period beginning June 23, 2017.  Also please note that I have 10 days for a forecast, but our trip will only be 7.  What I'm doing down below will help us determine which 7 days we chase.  Not every day is having great storms depicted on every model, so I've put the best-looking location for at least decent storms.

Day 1 (June 23):
GFS: eastern KS
GEFS: eastern KS
GDPS: TX panhandle/southwest KS
ECMWF: eastern KS
CFSv2: southwest NE to eastern NM

Day 2 (June 24):
GFS: OK/TX border
GEFS: northern OK
GDPS: TX panhandle
ECMWF: southeast CO
CFSv2: eastern CO

Day 3 (June 25):
GFS: southern TX *OR* central AB (oy)
GEFS: eastern KS
GDPS: southwest TX/southeast NM
ECMWF: western SD or western NE
CFSv2: eastern CO/northwest KS

Day 4 (June 26):
GFS: TX panhandle to southeast SD
GEFS: western KS
GDPS: southeast CO
ECMWF: eastern KS
CFSv2: most of ND and SD

Day 5 (June 27):
GFS: southeast SD
GEFS: northeast KS
GDPS: southwest KS
CFSv2: southeast IA

Day 6 (June 28):
GFS: western SD/eastern MT
GEFS: northeast KS
CFSv2: western NE/northeast CO

Day 7 (June 29):
GFS: southwest MN/northwest IA
GEFS: northeast KS or Black Hills
CFSv2: southwest KS

Day 8 (June 30):
GFS: northeast NE
GEFS: Western-central IA
CFSv2: northwest KS/southwest NE

Day 9 (July 1):
GFS: eastern NE
GEFS: Western IA
CFSv2: most of NE/western IA

Day 10 (July 2):
GFS: northeast KS, eastern IA, eastern Dakotas, western MN
GEFS: Central SD
CFSv2: eastern NM

At this point, it looks like we will likely be chasing south of the 49th parallel.  This makes sense because, up to this point, deep moisture has yet to consistently make it north to Canada.  This is about the time of year when it really gets advected in, but right now it doesn't appear to be in the cards.  So please please PLEASE, remember your passports.

Aside from saying that we'll most likely be south of 49, it's tough to say exactly where.  There seems to be a somewhat consistent signal that the 23rd will be a KS day--and if we choose to leave that day, there's no way we'd be able to make it there in time.

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