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2016 Atlantic Hurricane season


Jason WX

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Long-range guidance (CanSIPS, NMME, CFSv2, etc.) has been fairly consistent in depicting a 2011-type summertime pattern at 500 mb, with a mean ridge over the southern High Plains and a weakness over the western Atlantic. That type of pattern would be mostly very unfavorable for storms to hit the United States, unless homegrown MCV-type/frontal development were to occur in the northern Gulf of Mexico. Otherwise, storms approaching from the MDR would likely curve out to sea or continue into the Caribbean, where westerly shear may be elevated thanks to the tenacious +PDO (shown by all guidance for ASO '16), with attendant warmer-than-average SST projected off the Pacific Northwest and Baja California. We'll likely have a slightly-above-average season with few, if any, U.S. landfalls.

 

2011 tracks

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Question I thought some of you may know the answer to.  In the various seasonal forecasts for Atlantic Basin tropical activity, for each predicted/observed parameter, such as named storms, hurricanes and major hurricanes, I've seen forecasters typically issue forecasts for below normal, normal or above normal observations vs. past history.  What I'm not sure of is what do these forecasters consider below normal, normal and above normal?  

 

For example the CSU forecast for last year includes a table of median values from 1981-2010 for named storms (12.0), hurricanes (6.5) and major hurricanes (2.0).  However, then don't define, anywhere, what below normal, normal and above normal are for these three observations.  I assume there are ranges that the average of the bottom third of seasons meets, that the middle third of seasons meets and that the upper third of seasons meets.  

 

If they don't show what these ranges are for each outcome, it's hard to verify their accuracy scores.  Later in their verification report for 2015, they include Table 6, which shows how many of the past 17 seasons they correctly predicted below or above normal forecasts for 7 parameters, including the 3 I've been discussing (named storms, hurricanes and major hurricanes).  They don't show how many of their predictions were for "normal" vs. the normal range.  I'm actually wondering if this is simply a binary outcome of just above or below normal, such that the 70-80% "accuracy" scores they list should be compared to 50% probability of being right from guessing (with only 2 outcomes) instead of the 33% probability of being right (with 3 possible outcomes - below, normal and above normal) I've been assuming based on climatology.  70-80% accuracy is still very good vs. 50% expected, but not nearly as good vs. 33% accuracy expected if one guessed.  

 

For named storms, they had 15 of 17 seasons correct with regard to being above or below average, for hurricanes, they had 13 of 17 seasons correct with regard to being above or below average, and for major hurricanes, they had 13 of 17 seasons correct with regard to above or below average.  Does that mean none of their forecasts were for "average" years?  I know that's not true, which is why I find it confusing - for 2016, they're predicting an average year, but surely that can't mean they're only correct if they hit the median numbers right on the nose.  Am I missing something obvious here?  Thanks in advance...

 

http://tropical.atmos.colostate.edu/forecasts/2015/nov2015/nov2015.pdf

 

http://tropical.atmos.colostate.edu/forecasts/2016/apr2016/apr2016.pdf

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Please note, there's a hurricane season contest thread (pinned) and you can enter up to June 1st without penalty, probably on June 2nd also, I will start imposing late penalties when it seems that we have the usual number of entrants if no early June storms loom.

 

Entrants will find all instructions in post #1 of that thread, but just to inform you in advance, the seasonal count will include already-happened Alex (January) which counted for 1/1/0 and will also include Bonnie, so if that doesn't exceed t.s. limits, you go into the contest at 2/1/0 and add on what you think the rest of the 2016 season will produce.

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The setup on the ECMWF and GFS is somewhat intriguing. Shows the tail end of a cold front getting caught underneath a building West Atlantic high in a rather prime region for development. Also has some light support from the ensembles as well. Obviously a ways out, but I'd like this setup for the seasons first truely interesting system with the ridge overhead and proximity to the Gulf Stream.

Something to watch.

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Sent from my SM-G925V using Tapatalk

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The current lemon which is almost over the Yucatan has a decent chance of developing in the BoC. Nothing exciting, TD or TS Danielle tops. Upper level conditions should be marginal, becoming favorable near landfall in the SW GoM (around 21N).

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Latest TWO talks about the well defined center. I agree that we may have a TD by morning and a TS at the time recon reaches the system. Latest models show a much improved upper level environment several hours prior to LF, with an anticyclone developing overhead the system.  If this pans out, it will depend on the cyclone structure at the time if it can go some significant intensification prior to LF.

 

Based on the above, my best guess is a mid end TS Monday morning, near or just south of Tampico.

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