United States Winter 2017-18 Forecast

Written by on November 1, 2017 in Autumn 2017, Summer 2017, United States of America with 0 Comments

Today’s winter forecast is based on all current global atmospheric/oceanic drivers in place, their current status and model projection.

Here are the main factors taken into consideration for the upcoming 2017-18 winter for the US.

Low Arctic Sea Ice/High Eurasia Snow Cover = negative Arctic/North Atlantic Oscillation?

Arctic sea ice as well as Eurasian snow cover continues to expand fast now that we’re into November. But how does these two players compare to normal?

A long term trend of below normal Arctic sea ice coverage continues but less extreme than previous years such as 2007 and 2012. Low Arctic sea ice winters favours above normal pressure over the arctic atmosphere. Another player favouring above normal heights over the Arctic is Eurasian snow cover. This October wound up above normal but not exceptionally and nowhere near as extensive as this time last year.

Via Judah Cohen

These two factors can also increase the possibility of a sudden stratospheric warming event. Something we’ve been teased with the last few winters but hasn’t come to fruition.

Both low sea ice and high Eurasia snow cover favours a -AO/NAO but there’s other factors like we’ve seen which can counteract. Last years super El Nino did that and brought both sides of the Atlantic a warm winter.

Weak La Nina

We’re on the cusp of a weak La Nina phase of the ENSO compared to strengthening El Nino at this time last year. Direct effects from La Nina over the US depend upon strength of La Nina and where coolest waters are positioned. Weak La Ninas tend to favour colder Northern Plains, Upper Midwest winters but warmer across the Southern tier with a dominant ridge off the Southeast coast.

Strong La Nina’s like El Nino’s are connected to warmer winters.

Pacific and Atlantic Sea Surface Temperature Profile

Current SSTA’s (sea surface temperature anomalies) show a cooling east equatorial Pacific and warmer northeast Pacific. In the Atlantic there’s a large cool pool extending out from the Davis Straits into the North Atlantic while warmth is positioned between North Carolina and Newfoundland.

Credit: Tropical Tidbits

There’s a warm-cold-warm tripole up the western side of North America.

The Forecast

Given the La Nina, Northern ocean SSTA profile as well as increased potential for -AO/NAO, this suggests a lively winter with frequent deep troughs driving cold into the Northern Rockies and Plains but with the Southeast possibly protected by ridging, the East may rarely witness the core of cold moving in proper.

Wettest conditions are likely to be across the North, driest across the South where drought may become an issue again next spring from Southern California to Florida.

The storm track will likely run from Boise to Oklahoma City up to Buffalo, NY. The interior East including Appalachians could well be in for a big snow year and even the Big East Coast cities could see a good snow year for some big snowstorms.

Core of the cold overall should focus on the North-Central to Upper Midwest region but in my opinion there’s too much ESE ridging and consequential  warmth in the below CFSv2 for December and too little cool January, February in the Northern Tier.

Credit: Tropical Tidbits

Credit: Tropical Tidbits

Credit: Tropical Tidbits

2m temperature

Credit: Tropical Tidbits

Credit: Tropical Tidbits

Credit: Tropical Tidbits

The only month which makes sense precipitation-wise is February.

Credit: Tropical Tidbits

Credit: Tropical Tidbits

Credit: Tropical Tidbits

Jamstec looks more likely!

Temperature for Dec-Feb 17-18


FEATURED IMAGE CREDIT: Youtube: Innerlocus

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