Day 2: Afternoon Transportation Briefing

As part of the first week of the 2013 Winter Weather Experiment, the Aviation Weather Testbed is working with the HPC Winter Experiment to produce a collaborative transportation briefing.
In addition to collaboration with the HPC, this forecast was also produced with collaborations involving NWS WFO forecasters and the experimental Global Graphics forecasting desk that is part of the experiment.

One of the AWC National Aviation Meteorologists (stationed at the FAA System Command Center) is participating in the HPC Experiment this week and is focusing on communicating precipitation types and timing.  The graphic below was produced by an AWC forecaster in Kansas City and focuses on the icing, turbulence, and IFR conditions associated with a system that is forecast to impact the east coast on Feb 14-15.

Transportation briefing graphic valid 14 Feb 00Z - 15 Feb 00Z.  Depiction of IFR, icing, turbulence, and wind threats associated with forecast cyclone.

One of the automated tools that is available to forecasters and air traffic planners is the Aviation Winter Weather Dashboard.  The dashboard translates winter weather as forecast by the SREF into terminal impacts based on how well the airport can handle certain winter weather events.  Below is a snapshot of the dashboard showing terminal impacts in the northeast as forecast by the 09Z SREF on 12 February.

Aviation Winter Weather Dashboard showing terminals in the Northeast.  Forecast from the 09Z SREF on 12 Feb.

Icing prediction using Mixing Ratios

Several of the products that we are looking at for this experiment use mixing ratios to predict regions of icing.  Both the AFWA and SREF ensembles use mixing ratio from each of the members to predict where icing will occur.

The AFWA takes a worst-case approach for explicit prediction of super-cooled liquid.  Shown below is the ensemble maximum SLD mixing ratio (shaded) with the lowest freezing level from the ensemble contoured over the top.  PIREPs for lgt-mod icing or greater have been overlaid on this forecast.'

11 Feb 00Z AFWA forecast of worst case of SLD mixing ratio and lowest freezing level height.  PIREPs are for lgt-mod icing, or greater.

Post-processing on the SREF takes a slightly different approach, looking at cloud water mixing ratio between 0 and -25 C in each member, and produces a probability that icing will occur.  PIREPs of lgt-mod icing or greater are also shown in this loop.

11 Feb 09Z SREF probability of icing.  PIREPs are for lgt-mod icing, or greater.

IFR Verification

As a follow-up to yesterday's post concerning probabilistic flight rule prediction, here are some quick verification images.  For the C&V prediction, the forecast period is 21Z - 09Z.

Each image contains the METAR observations of flight category overlaid on the gridded data set.  The first gridded data set is an analysis of observed ceiling and visibility conditions, the National Ceiling and Visibility Analysis (NCVA).  Hourly data is show along with the METARs that went into this analysis.

NCVA Field and METAR flight category for 21Z 11 Feb - 09Z 12 Feb.

The primary forecast concern in this area was the lifting of the ceilings, bringing terminals out of IFR conditions.  The dataset shown below is the GFS-LAMP IFR conditions.  Regions shaded in green are where the 18Z GFS-LAMP run from 11 Feb is predicting IFR conditions.  It clears the IFR conditions fairly well in PA/NJ/NY/CT, but keeps DL/MD/VA in IFR conditions too long.

11 Feb 18Z GFS-LAMP forecast valid same period as NCVA.

Additionally, the SREF and AFWA probability of flight category as highlighted in yesterday's post is show below.  The SREF is the 09Z run from Feb 11, and the AFWA is the 00Z run from the same day.  Only the MVFR and IFR conditions are shown in each of these products. The SREF forecast does not seem to discriminate well between MVFR and IFR conditions (all or nothing) and clears the IFR conditions along the northeast coast fairly well.  The AFWA forecast tends to clear the IFR conditions to quickly along the northeast coast.

Another feature of both of these forecast is the forecast areas of IFR around the Great Lakes region that did not verify.  MVFR conditions were observed in MI and NWRN OH.  In the SREF this area is especially overdone and we are again seeing the issues that the SREF has discriminating between MFVR and IFR conditions.  The are in the AFWA is also overdone, with IFR conditions forecast in PA where only MVFR was observed.

11 Feb 09Z SREF forecast valid same period as NCVA.

11 Feb 00Z AFWA forecast valid same period as NCVA.

Day 2 of the Winter Weather Experiment

Good morning and welcome to Day 2 of the 2013 Aviation Winter Weather Experiment. We have a few new faces in the room today. Visitors from NTSB and the local WFO joined our other visitors from AFWA, NCAR, GSD, NASA, and Lockheed Martin.

We have already had a busy morning of assessment and verification of yesterday's model and human forecasts. Check out the IFR Verification blog for additional information. Additionally, morning weather briefings set the stage for today's hazards and focus regions. The ceiling and visibility desk forecasters are looking in the Pacific Northwest for low ceilings and will focus on the South from the Houston and Fort Worth regions shifting towards Memphis and Atlanta as the day progresses.  The turbulence desk will focus along the east coast/Atlantic seaboard with low level wind shear presenting a problem along the GA and SC coast and low turbulence over PA. Forecasters will also keep an eye over soutwest Texas where lowel level turbulence will likely be a hazard today. Finally, the icing desk will be focusing on developing storm over the central plains and icing hazards in the NE from West VA northeastward up to Maine.

Ensemble Prediction of Flight Rules

One of the things being explored in the Winter Weather Experiment is the use of mesoscale and high-resolution ensembles for prediction of ceiling and visibility.  The two primary ensembles being explored for this purpose are the Short Range Ensemble Forecasting (SREF) System and the Air Force Weather Agency (AFWA) mesoscale ensemble.

The SREF is composed of 21 ensemble members with post-processed output on a ~16km horizontal resolution, while the AFWA ensemble has 10 members run at a ~4km horizontal resolution.  Each individual member is obtained by the Aviation Weather Center where we perform additional analysis that is not done in the basic ensemble post-processing.

Each of the individual member solutions contains a prediction of ceiling and visibility, for which ensemble statistics are computed.  Additionally, the flight rule category is computed for each ensemble member, from which the probability of the flight category can be determined.

These probabilities for the time period between 21Z Feb 11 - 09Z Feb 12 are shown for the AFWA and the SREF below.  Note that these probabilities are not calibrated and weight each of the ensemble members equally.  Both the weighting of the members and the calibration will need to be explored in order to improve the reliability of these forecasts (see: Reliability and Resolution). 

Probability of Flight Rules as predicted by the 00Z AFWA from 11 Feb 2013.  Valid 21Z 11 Feb - 09Z Feb 12.  MVFR, IFR, and LIFR conditions are shaded in blue, red, and yellow, respectively, shaded starting at 40%.

Probability of Flight Rules as predicted by the 03Z SREF from 11 Feb 2013.  Valid 21Z 11 Feb - 09Z Feb 12.  MVFR, IFR, and LIFR conditions are shaded in blue, red, and yellow, respectively, shaded starting at 40%.

2013 Winter Weather Experiment Kick-Off

Good morning! The 2013 Aviation Winter Weather Experiment has officially started. With visitors from NCAR, AFWA, Lockheed Martin and AWC forecasters, we have a full testbed! Forecasters will use a wide range of operational and experimental products as guidance when issuing their products. Cutting-edge GOES-R products, high-resolution deterministic models and ensembles, assessment tools, and displays are being debuted in the testbed over the next couple of weeks for the forecasters to evaluate and provide feedback for the developers.  Please come see us in the testbed if you can or check back here for more information.

Winter Weather Experiment

The first ever Aviation Winter Weather Experiment will kick-off on Monday, February 11th at 8:00 am in the Aviation Weather Testbed! Please visit the 2013 Winter Weather Experiment webpage for information on data sets, displays, and tools that will be utilized during the experiment.