Denver, Colorado

NOAA, AccuWeather Issue 2014-2015 Winter Outlooks

Posted by @brendansweather

It is always an exciting time of year when meteorological organizations start issuing their winter outlooks, often conflicting with one another and even themselves.

This week both AccuWeather and NOAA released their Winter Outlooks. As is typically the case, NOAA’s outlook is far more conservative with any bold predictions (much of the country, according to them, will see equal chances for near-normal, colder than normal, and warmer than normal temperatures), while the AccuWeather’s outlook is a bit more descriptive for most regions.

NOAA’s Winter Outlook
NOAA has put out an outlook that features a warm west western US and a cool South. The outlook from NOAA's Climate Prediction Center will not come as welcome news for those in the west hoping for a real winter. For Dec-Feb NOAA has greater than 50% chances for warmer than normal temperatures across the west, with equal chance for much of the middle of the country (including Colorado), and greatest odds for below normal temperatures across the South.

NOAA Winter Outlook 2014 - 2015 TemperaturesSource: NOAA

As for precipitation, Colorado is again under the equal chances category -- with the exception of extreme southern Colorado which is included in the >33% chance for above normal precipitation (looks very Nino).

NOAA Winter Outlook Precipitation 2014-2015Source: NOAA
AccuWeather Winter Outlook
The outlook from AccuWeather is in many ways very similar, and looks highly based on climatology. They too are predicting a mild and dry Northwest and wet South. Their outlook, however, includes “snowy periods” for much of Colorado (that’s the case every winter I think), and a good area of “cold” across the middle of the country (anyone remember last winter?). In fact, their outlook specifically calls for a return of the Polar Vortex by January and February.

AccuWeather Winter Outlook 2014-2015Source: AccuWeather

Brian will be discussing our latest thoughts on the long-range outlook at tonight’s meetup; we look forward to seeing you there!

The Impact of Pacific Typhoons on the United States

Posted by @MattMakens247wx

The 2014 tropical storm season has favored the Pacific, while it’s been much quieter in the Atlantic
The Pacific tropical season has been an active one. We’ve seen 19 storms so far this year, with 16 being average total seasonal number. The 19th is Vongfong, currently hammering Japan.

Meanwhile, the Atlantic season has been very quiet. Gonzalo is just the 7th named storm in a season that averages 12. Gonzalo is not likely to impact the US as the current projection takes it over the eastern Caribbean islands north to northeastward over the open Atlantic, curling away from mainland US.

Hurricane Gonzalo Forecast MapWhile we typically defer our attention to the Atlantic for tropical system impact on the US,the Pacific can have a bigger impact on the weather the country experiences as a whole -- albeit indirectly.

Remember Typhoon Haiyan of last year? That’s the one that decimated sections of the Philippines. A quick summary on this, one of the most powerful typhoons ever recorded:

  • Formed          November 3, 2013

  • Dissipated        November 11, 2013

  • Highest winds    10-minute sustained: 230 km/h (145 mph)

  • 1-minute sustained: 315 km/h (195 mph)

  • Lowest pressure         895 mbar (hPa); 26.43 inHg (Estimated)

  • Fatalities         6,340 confirmed, 1,061 missing

  • Damage          $2.86 billion (2013 USD)

Well, about ten days after Haiyan slammed the Philippines, it’s energy contributed to the mid-November tornado outbreak in Indiana -- some 8,000 miles apart!

The 17th of November, 2013 had 73 tornadoes across the midwest, most in Indiana and Illinois. Two of those 73 were rated EF-4. (yes this report page says there were 136 tornadoes, but remember those reports may include multiple reports  for the same tornado).

SPC storm reports 11/17/13Source: SPC

That outbreak was the second worst in Indiana history, and, yes, it happened out of the traditional severe weather season, but during what’s often referred to as “
second season”.

Compare Haiyan to Vongfong
Vongfong, meaning ‘the wasp’, first made landfall near Okinawa, Japan on Sunday with wind more than 100 mph. Just Friday the storm had wind of 155mph.

Vongfong from the International Space StationVongfong taken from the International Space Station on October 8, 2014

At least 61 people were injured, and more than 44,000 were left without power; one person remains missing from the storm’s impact Sunday, according to
the Japan Times.

Imagine the chaos involved with the 506,000 people ordered to evacuate. Especially with much of public transportation shut down with nearly 16 inches of rainfall expected.

This is the second typhoon to hit japan in a week, last week we were tracking Typhoon Phanfone which is the one that killed three us airman stationed at Okinawa.

Although Vongfong is one of the strongest this season, the typhoon did not reach the intensity of Haiyan. Haiyan had a minimum central pressure of 895mb and peak wind of 195mph versus Vongfong’s 900mb minimum pressure and 155mph peak wind.

Like Haiyan, Vongfong (and Phanfone for that matter) has utilized a lot of potential energy to create itself.


Energy headed to US
Typhoons contain a great deal of energy -- we are talking energy on the order of tens of  thousands of nuclear weapons. In the meteorology community, this energy is known as vorticity, or spin of the storm. This energy doesn’t simply disappear as a storm weakens and dies; it is utilized by the atmosphere somewhere else.

In the case of the past two typhoons that hit Japan -- Phanfone and Vongfong -- their energy is grabbed by the jetstream and taken toward Alaska and the lower 48. So, Japan may have been hit directly by the typhoons, but we too may have that energy impact us down the line.

Toward Halloween, we will be tracking several pushes of colder air that will try to hit our area. The Great Lakes and Eastern US will certainly feel the cold, but Colorado may be on the edge of these systems. The energy pushing this cold at us is partially that from the typhoons.  Weather is a “crazy cycle”.

The CFSv2 and ECM are hinting at some cold conditions with associated 500mb troughing near late October and early November. Part of the energy creating these troughs is that of the current typhoon(s).

The State of the Atmosphere: Sunday, October 12, 2014

Posted by @brendansweather

The weather pattern really quiets down over the next week to 10 days after today’s system works through the region and exists Monday. If you’re not quite ready for snow, this forecast is for you; if you’re jumping at the bit for our first measurable snow… we’re going to keep you waiting a while longer.

Sunday and Sunday night
Afternoon highs will be chilly across the region Sunday, as a strong upper level trough passes through. We may see our high temperatures for the day early, with temperatures dropping into the 40s and low 50s through early evening. Morning lows Monday will be in the low to mid 30s for lower elevations, with widespread 20s forecast at higher elevations.

There will be some moisture to work with associated with this system, but most should come in the form of rain for lower elevations. The coolest temperatures of the coming week will work into the region Monday morning, but likely
after the best chance for precipitation at lower elevations.

At higher elevations there will definitely be some snow. The latest ECMWF produces upwards of 7 inches for the higher peaks of north central Colorado through Monday morning.

GFS 3 hour QPF 00z tonight. Snow at higher elevations, rain showers at lower elevations.
GFS precipt type map ColoradoWeather5280

The week ahead
By Monday we really start to clear things out. The week ahead looks to be very quiet and warm overall. Our Sunday/Sunday night system will push into the middle of the country sparking several days of severe weather across the south central U.S. and eventually up into the mid-Atlantic. Behind it, high pressure builds in and we enter a period of sustained quiet weather.

Really all ensemble suites are in pretty good agreement with this. A large trough off the west coast, upper ridging across the mid-section of the U.S., and troughing to the east for the next week -- if not longer. Typhoon Vongfong is forecast to recurve and eventually help to super-change that trough off the west coast which offers additional confidence to this pattern.

Vongfong GEFS Ensemble Guidance
Vongfong guidance trackSource: WeatherBell Analytics

Deep trough in the northern Pacific Ocean, ridging overhead…

GEFS 500 hpaSource: WeatherBell Analytics

The pattern can’t last forever. Our attention will start to shift toward the latter part of October and beginning of November for possibly the best chance at seeing winter finally arrive.

Meetup Thursday!
Thursday is weather meetup day, and we hope to see you there (weather won’t be an excuse!). There are still a few tickets left, and while free (you don’t need to bring your ticket to get in), we do ask that you let us know if you’re coming so we have some idea of how many to expect.


We’ll try to get started as close to 6:30pm as possible. There will be three presentations and some time to hang around and chat afterwards. If you’ve got a favorite snow dance, maybe you’ll consider sharing it with the group, as it seems we need it!

Colorado Rainfall Totals October 9th, 2014

Posted by @brendansweather

Precipitation analysis for yesterday’s rain event across Colorado is in, and it paints a pretty wet picture. As forecast, areas south of Denver did best with this system, but even northern Front Range communities saw anywhere from 0.5 to 2 inches of rain. Our weather station (2m S downtown Denver) received 0.59 inches from this system.

We outline the Palmer Ridge as the focal point for heaviest rainfall, and take a look:

Colorado rainfall totals map Oct 9, 2014Source: WeatherBell Analytics

The Colorado Springs area saw some of the greatest rainfall totals. COS airport reported a record 2.83 inches Thursday, crushing the old daily maximum rainfall for the date of 0.59 inches set in 1967.

Southeast Colorado saw some good rainfall totals too. Rainfall totals from 0.5 to 2 inches were common across some of the spots still hit hardest with drought. Worth noting that as of this week 69.29% of the state is now drought-free, while this was true for only 32.04% of the state to start the year. Oh the pattern…

Drought Monitor ColoradoSource: Drought Monitor

We’ll stay cool today, warm a bit for Saturday, before another shot of cooler air and precipitation chances return for Sunday across much of the state.