Watching the Skies

Looks like we’ll have another relatively dormant weather pattern for us the next few days. An upper level high pressure is building into the region bringing clear, quiet and dry conditions for the next five days. Highs will remain in the mid 70s, lows in the low to mid 50s. Overall these temps are quite seasonable for this time of year. Moisture may begin to return to the region on Saturday and Sunday, with a possible cold front passing on Sunday bringing rain chances for that day. Overnight lows this upcoming weekend will warm slightly with the increase in moisture. Temperatures will be cooler after the frontal passage, current forecasts indicate highs in the low 60s and lows in the mid 40s. No severe weather is forecast for the next 7 days at this time.

You may also be wondering when is it going to get real cold here? Well nobody knows for sure, but when you consider weather history from years past, the answer would be ’soon’. According to the National Weather Service, DFW Airport’s average first freeze date is November 22. This, coupled with this years climate forecast indicating above average precipitation and normal or slightly below normal temperatures, might indicate that we can expect our first freeze within the next two to three weeks. Below is a graph of the average freeze days recorded per month from DFW Airport. You can see that December and January will likely be the two coldest months of the season.

For more information including seasonal averages and extremes, see the Freeze Summary for DFW Airport, provided by the National Weather Service.

As a side note, Tropical Storm Ida is about to make landfall in Mobile, AL with 60mph winds. The storm encountered strong upper level wind shearing and cooler gulf water temperatures and lost a majority of its strength prior to landfall. There is still some minor flooding occurring along several southern Alabama and extreme western Florida panhandle counties. Additionally high street flooding and 5 foot storm surge is reported in eastern New Orleans in areas outside the hurricane flood control system. This storm is forecast to make a right hand turn and dissipate within 36 hours.

-- Weather in Frisco, TX when posted --
Temp: 62.6 °F, Dew: n/a, Humidity: 74%
Wind: n/a at n/a
Sky: n/a

This won’t be an extensive review on climate change, simply an observation of current trends and its known impacts based on the past. So far this year El Nino conditions have popped up with average sea surface temperatures in the pacific tropical zone at least 1.0 degrees C above average. El Nino has been known to affect weather patterns globally including less tropical cyclone activity in the Atlantic basin during El Nino periods.

Looking at the Climate Prediction Center’s 6-10 day and 8-14 day forecasts, north Texas can expect more above average temperatures and below average precipitation. Keep in mind these forecast begin 6 days out, which will be after the rain event we will encounter the next several days. Beyond that, El Nino conditions tend to create warmer than average, as well as stormier than usual conditions for north Texas in the Winter.

Below is a small list of reports that NOAA, the National Weather Service, and AccuWeather have put together regarding recent observations where weather conditions have departed from normal.

El Niño Arrives; Expected to Persist through Winter 2009-10

El Niño’s impacts depend on a variety of factors, such as intensity and extent of ocean warming, and the time of year. Contrary to popular belief, not all effects are negative. On the positive side, El Niño can help to suppress Atlantic hurricane activity. In the United States, it typically brings beneficial winter precipitation to the arid Southwest, less wintry weather across the North, and a reduced risk of Florida wildfires.

El Niño’s negative impacts have included damaging winter storms in California and increased storminess across the southern United States. Some past El Niños also have produced severe flooding and mudslides in Central and South America, and drought in Indonesia.

An El Niño event may significantly diminish ocean productivity off the west coast by limiting weather patterns that cause upwelling, or nutrient circulation in the ocean.  These nutrients are the foundation of a vibrant marine food web and could negatively impact food sources for several types of birds, fish and marine mammals.

NOAA: Global Ocean Surface Temperature Warmest on Record for June

The world’s ocean surface temperature was the warmest on record for June, breaking the previous high mark set in 2005, according to a preliminary analysis by NOAA’s National Climatic Data Center in Asheville, N.C. Additionally, the combined average global land and ocean surface temperature for June was second-warmest on record. The global records began in 1880.

Climatology of Hurricane Seasons with a Late Start – By NWS WFO Ruskin

As expected, there is no major correlation to a late start to the season and characteristics of the season. Several seasons saw 10 or more TCs form with 5 or more landfalls, while other years saw 4 or 5 storms form with just a couple landfalls.

3,000 Low Temp Records Set This July! – By AccuWeather.com

1,044 daily record low temperatures have been broken this month nationwide according to NCDC — count record “low highs” and the number increases to 2,925, surely to pass 3,000 before the end of the month.