Note: Neither the Frac Spread feature nor the Midstream Monitor newsletter will appear next week due to the Thanksgiving Day holiday.

The hypothetical NGL barrel claimed another high for the year, but a spike in natural gas spot prices combined with little movement for NGL to cut into margins last week. In the case of ethane, the cuts were deep.

The Mont Belvieu, Texas, barrel came within 1 cent of $33, its highest level in three years. At Conway, Kan., the barrel’s high for 2017 was also the fifth week in the last eight above $30 and the highest price since Thanksgiving week 2014.

While ethane prices have struggled in the aftermath of Hurricane Harvey’s impact on Gulf Coast ethylene facilities, propane, butane and isobutane have ducked and weaved around year-highs in recent weeks. C5+, however, has been on a steady upward march since the Fourth of July.

The price of natural gasoline has advanced in 13 of the 17 five-day (Wednesday to Tuesday) trading periods that Hart Energy defines as “weeks” in that time at Mont Belvieu, resulting in a 37.6% increase. At Conway, the 28.2% rise was accomplished with hikes in 10 of the 17 weeks.

Those prices are the highest since late-March 2015 at Mont Belvieu and mid-December 2014 at Conway. They are 44.5% higher than the Mont Belvieu low for the year, set in mid-June, and 34.7% higher than the Conway low set at the same time.

Natural gas prices spiked Nov. 8 as a cold front gripped the northern tier of the U.S., but subsided as the weather returned to seasonal norms. The week’s average, however, was about 9% higher at Mont Belvieu, cutting the ethane margin from almost 8 cents per gallon to 5.3 cents.

En*Vantage sees the stalling of ethane prices as a balancing of five ethylene plants out of commission (three due to damage from Hurricane Harvey and two for maintenance) and the recent opening of Dow’s ethane cracker in Freeport, Texas. Add in the OxyChem/Mexichem in Ingleside, Texas, and LyondellBassell’s expansion in Corpus Christi, Texas, along with the recent burst of exports from Enterprise Products Partners LP’s (NYSE: EPD) Morgan’s Point terminal on the Houston Ship Channel and ethane has weathered the storm fairly well.

“We can only see upside for ethane prices for the rest of the year and into the first half of 2018,” En*Vantage said. That’s because all five plants that are down will return, and by the end of second-quarter 2018, almost 300,000 barrels per day of new cracking demand will be in place. That does not take into account the possibility of additional ethane exports.

Storage of natural gas in the Lower 48 decreased by 18 billion cubic feet (Bcf) in the week ended Nov. 10, the U.S. Energy Information Administration reported, above the Bloomberg consensus of a 15 Bcf dreaw and below the 2016 increase of 34 Bcf. It is the first draw of the season. The figure is also below the five-year average increase of 12 Bcf, resulting in a total of 3.772 trillion cubic feet (Tcf). That is 6.7% below the 4.043 Tcf figure at the same time in 2016 and 2.6% below the five-year average of 3.873 Tcf.

Joseph Markman can be reached at jmarkman@hartenergy.com and @JHMarkman.