Winter Weather Cripples Southern Airports, Deicing Operations Begin (Credit: Meteorologist Jessica Olsen)
Amid heavy winter weather experienced in parts of the country as we wrap up 2017, many are still taking this opportunity to conduct last minute travel for the New Year. Despite an extremely cold start to 2018, locations in the middle of the CONUS are experiencing subzero wind chills with temperatures in most locations from the Gulf to the Carolinas below the freezing level.
Heavy delays and cancellations are being seen in Dallas-Fort Worth Airport (DFW) as they contend with ice and temperatures upwards of 30 degrees below normal. Winter weather advisories are issues for western and central Texas while eastern Texas, Louisiana, Mississippi and Alabama are seeing a hard freeze warning all impacting travel this weekend into the start of the work week.
It’s no surprise that DFW is seeing delays however remaining away from cancellations due to the process of deicing. Delays are expected due to deicing, however freezing conditions at the airport play a critical role in how aircraft performance is seen in the skies. Passengers often ask why deicing is necessary, and the process ensures that buildup of snow and ice will not be present on the aircrafts’ control surfaces (ailerons, elevator, stabilizer, flaps, slats, rudder). Deicing fluid is a mixture of glycol and water. This fluid is then heated and sprayed on the control surfaces and fuselage if necessary to prevent buildup. Optimal aircraft performance is achieved when there is little to no accumulation on its surfaces. Note, when aircraft are inflight the subzero temperatures at higher altitudes present difficulties and decrease engine performance, which is why it is critical for any initial accumulation to be removed on the ground.
Airlines are indicating to verify flight statuses before arrival, in addition to possible delays due to the deicing process.
For more information on winter weather and aviation visit the Global Weather and Climate Center!
© Meteorologist Jessica Olsen
This is called a METAR, or Meteorological Aviation Report. They’re generated by weather stations at airports! It’s a shorter way to describe the weather for aviation purposes.
The METAR consists of two parts, the body and the remarks. We’ll talk about the body first.
METAR: There can be two reports, either the standard METAR or a significant weather event, which in that case will begin with SPECI.
KBNA: This is the station name. The first letter will either be a K or a C. U.S. stations start with a K and Canadian stations start with a C. The next 3 letters are the station name. This METAR came from Nashville International Airport in Tennessee.
272153Z: This is the date and time of the report. The first two numbers (27) are the day of the month. In this case, this report came on the 27th. The next 4 numbers (2153) are the time. This was reported at 21:53 Z, which is 4:53 PM CDT.
02005KT: This tells you the wind information. The first 3 numbers (020) tell you the direction of the wind, given in degrees. In this one, the wind is coming from the north east. The next two numbers (05) tell you the wind speed. In this report, the speed is 5 knots.
10SM: This is the visibility. Here, the visibility is 10 statute miles.
BKN070: This is the cloud coverage. The first 3 letters (BKN) show how much of the sky is covered. In this case, BKN means Broken where 51-87% of the sky is cloudy. The next three numbers (070) are the height of the cloud base in hundreds of feet. Here, we have broken clouds at 7000 feet.
27/11: This is the temperature and dew point, in Celsius. Here, the temperature is 27°C while the dew point is 11°C. This converts to ~81°F and ~52°F.
A3008: This is the altimeter reading. This gives the pressure in inches of mercury. This would be the pressure if this station were at sea level.
Now we have the Remarks section. This section is only added when appropriate. This will start with RMK.
AO2: This says that there is a precipitation discriminator at this station, and it is an automated station!
SLP180: This is the sea level pressure. SLP stands for sea-level pressure. The three numbers after it (180) give reading in hectopascals. If the number is less than 500, a 10 is put in front. If it’s more than 500, a 9 goes in front. A decimal goes in between the second and third numbers. In this case, the sea level pressure would read as 1018.0 hectopascals.
T02720111: This is the precise temperature and dew point, as before it is given in degrees Celsius. The first four set of digits (0272) is the temperature. The reason for the 0 in front is that it designates the sign. If it’s a 0, it’s positive. If it’s a 1, it’s negative. In this case, the temperature is 27.2°C. Same process for the dew point. In this case, the dew point is 11.1°C.
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©2017 Weather Forecaster Jennifer Naillon
Discussion: With 12 active fires as reported by CalFire it is no surprise that residents and travelers in the Southern California region have growing concerns regarding the reach of the current wildfires. Of major concern is the Thomas Fire, having burned 237,500 acres in Santa Barbara and Ventura Counties.
Severe fire weather has continued in the area as crews are fighting to increase containment beyond 25%. Reviewing the synoptic picture, we see that the United States is dominated by several key features which are impacting the continued devastation of this fire and the 11 others in the immediate area. With a large ridge in the West coast and high-pressure system placed seemingly strategically to the north with a strong low in the upper mid-west this allows the feeding of the Santa Ana winds in the Southern California region. These winds couples with warmers than average December temperatures and extremely low-relative humidities are making this a head on fight for fire personnel.
Earlier this month California Governor Jerry Brown declared a state of emergency as these fires threaten Los Angeles, Santa Barbara, San Bernardino and other cities which included threats to the 405 and other freeways that are the backbone of the Southern California commute. Delays were initially issued for buses servicing the Los Angeles (LAX) and Van Nuys General Aviation (VNY) airports, but have been lifted. Additionally, no aircraft delays have been reported in correlation with fires however it is expected that increased traffic throughout the region may pose delays in arrivals to the airport. With regional airports such as San Luis Obispo (SBP), Fresno (FAT), and Monterey Regional (MRY), these will provide the much-needed safety net for any issues that may arise in diversion situations for LAX and VNY.
For more information on local wildfires and aviation concerns visit the Global Weather and Climate Center!
© Meteorologist Jessica Olsen