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November 2015 Discussion


IWXwx

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Indiana & Ohio primarily as it sits right now but I wouldn't consider Illinois, Kentucky, or Michigan out of it. As powerball noted though, there's no negative tilt...just pretty robust shear and helicity numbers. If we can get CAPE over 250 I can see a low-topped line happening. Reminds me of a less intense version of the Halloween 2013 system.

Ah, and that's from the 12z run of the EURO?
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Ah, and that's from the 12z run of the EURO?

Yeah, position and movement are very similar but this system only looks to be barely sub-1000 mb (although deepening at the same time) while the 2013 system was already sub-990 mb when the front entered Ohio. So the strength is significantly less but things can still change.

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ECMWF does have decent dynamics by the looks of it but not a whole lot of CAPE.  Timing may be less than ideal for a large part of the area but these fall events don't seem to care about timing sometimes.  Always tricky to figure out just how much CAPE is needed for these more dynamic fall events.

 

ECMWF has 850 mb dews of 12C into southern Michigan...good stuff for this time of year.

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Right now it would appear mid level lapse rates are going to be a mitigating factor. It's 2015 though so that's not really a surprise. The Euro and CMC solutions certainly evolve into more potent setups than the GFS. Like Hoosier said, these high shear / low instability events can be tricky. 

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ECMWF does have decent dynamics by the looks of it but not a whole lot of CAPE.  Timing may be less than ideal for a large part of the area but these fall events don't seem to care about timing sometimes.  Always tricky to figure out just how much CAPE is needed for these more dynamic fall events.

 

ECMWF has 850 mb dews of 12C into southern Michigan...good stuff for this time of year.

 

Agreed, could see a low end slight risk event for most of the forum out of this.

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Right now it would appear mid level lapse rates are going to be a mitigating factor. It's 2015 though so that's not really a surprise. The Euro and CMC solutions certainly evolve into more potent setups than the GFS. Like Hoosier said, these high shear / low instability events can be tricky. 

 

Hopefully they are workable and not something really putrid like <6 C/km.

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Still 5 days out but for multiple days the Euro has been showing a significant system pushing through the area with favorable timing on Friday with respectable QLCS potential. The SPC hasn't really bought in but I wouldn't be too surprised if we get a D4 slight if the models come into agreement. The GFS has been all over the place but up until 84 hours out, the Euro matches the NAM very well. It'll be interesting to see if the NAM stays in-line with the Euro or the GFS over the next day or so.

 

EE rule in effect.

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18z GFS was quite a bit different than 12z for the late week storm.  I guess we'll know soon enough if it's really playing catch up to the EC/GGEM. 

 

Anyway, looking at 700-500 mb lapse rates on the 18z run, there's a plume of decent lapse rates that moves over the area on Thursday but by the time the system approaches, they trend down to around 6 C/km.  Sfc-850 mb moisture return is not as robust as the other models, but again, could be playing catch up.

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This may end up not panning out, but with forecast highs in the low 70s for O'Hare for the next 3 days, I thought I would check to see how often such a 3+ day streak occurs in November.  A streak of 3 or more days of 70+ has occurred 6 times.  Below I've listed all of those 3+ day streaks, as well as the 2 day streaks.  Going through the records I found that, quite often, 70 degrees in November has been a one day and done occurrence.

 

 

11/6/1916:  74

11/7/1916:  74

 

11/5/1924:  75

11/6/1924:  74

 

11/8/1931:  73

11/9/1931:  73

 

11/1/1933:  77

11/2/1933:  72

 

11/1/1938:  75

11/2/1938:  76

11/3/1938:  75

11/4/1938:  72

 

11/1/1944:  78

11/2/1944:  76

 

11/7/1945:  74

11/8/1945:  70

 

11/9/1949:  71

11/10/1949:  71

 

11/16/1952:  73

11/17/1952:  74

 

11/15/1953:  71

11/16/1953:  71

11/17/1953:  72

11/18/1953:  72

11/19/1953:  74

 

11/16/1954:  70

11/17/1954:  70

 

11/3/1964:  75

11/4/1964:  73

 

11/14/1971:  78

11/15/1971:  71

 

11/1/1974:  74

11/2/1974:  78

 

11/5/1975:  71

11/6/1975:  75

11/7/1975:  70

 

11/2/1977:  75

11/3/1977:  72

 

11/2/1978:  70

11/3/1978:  74

11/4/1978:  74

11/5/1978:  79

 

11/2/1987:  71

11/3/1987:  75

 

11/1/1990:  73

11/2/1990:  73

11/3/1990:  70

 

11/8/1999:  71

11/9/1999:  74

 

11/3/2005:  70

11/4/2005:  70

 

11/3/2008:  73

11/4/2008:  71

11/5/2008:  71

 

11/7/2009:  71

11/8/2009:  70

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WHILE GUIDANCE HAS TRENDED TO A MORE CONSISTENT EVOLUTION OF A
SHORTWAVE TROUGH EXPECTED TO BE INVOF SRN HIGH PLAINS ON THU
AFTERNOON...SUBSTANTIAL VARIATION PERSISTS IN THE DEGREE OF
CYCLOGENESIS FROM KS TO THE GREAT LAKES BY 12Z/FRI. A MARITIME
TROPICAL AIR MASS IS PROGGED TO BE CONFINED TO S/E TX AT
12Z/THU...WITH A MODIFYING CONTINENTAL AIR MASS ANTICIPATED TO ITS
N. LOW-LEVEL MOISTURE TRANSPORT FROM THE S WILL BE PRONOUNCED AND
SHIFT TOWARDS THE NE AS WINDS VEER. WAA/ISENTROPIC ASCENT SHOULD
YIELD INCREASING PRECIPITATION WITHIN THE MODIFYING WARM SECTOR AS
EARLY AS THU MORNING. AS SUCH...MID-LEVEL LAPSE RATES ARE LIKELY TO
BE MARGINAL SUGGESTING INSTABILITY SHOULD REMAIN MODEST EVEN WHERE
LOW-LEVEL MOISTURE IS RICH. GIVEN THE POSITIVE TILT OF THE
TROUGH...SOME DEGREE OF VEER-BACK-VEER WIND PROFILES ARE ANTICIPATED
WITHIN THE PRE-FRONTAL WARM SECTOR IN THE CNTRL TX TO SRN AR
VICINITY. THESE CONCERNS ASIDE...A SWATH OF STRONG WIND FIELDS WILL
OVERLAP AT LEAST PART OF THE MODEST WARM SECTOR CENTERED FROM THU
AFTERNOON TO FRI MORNING AND SHOULD RESULT IN AT LEAST A LOW
PROBABILITY DAMAGING WIND/TORNADO RISK.

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In case anyone was wondering, out of that list of years that I just posted for Chicago, only a couple even had a moderate El Nino going on (1987 and 2009). Many of those years were actually Nina.

I can find numerous Nina Falls with temperature patterns similar to this year, but only a few nino Falls and NO strong nino Falls. Not even close. Sensible weather isn't behaving like strong nino at all.
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