Max Ventilation Rate

Purpose: Ventilation rates are used by land agency personal to identify poor smoke dispersal days. Maximum ventilation rate forecasts represent the peak values for the day between mid morning to late evening. These values typically occur during the afternoon hours but that is not always the case. Ventilation rate is based on multiplying transport wind to mixing height. Mixing height represents the height of the mixed layer or the height a parcel of air would rise in the atmosphere due to atmospheric mixing or turbulence.  Transport wind is the average wind speed through the mixed layer. Adjective ratings or categories are set by each state. A “poor” rating in one part of the country may have a different set of values than another part of the country or state. The New Mexico air quality bureau uses 5 categories: Poor, Fair, Good, Very Good and Excellent.   This graphic is based soley on model forecasts and may not fully account for local weather phenomenon’s in mountain terrain areas (ie drainage winds etc). Keep in mind that a maximum rating may only be valid for one hour and is not necessarily indicative of ventilation for the entire day.

Color codes: Purple = Poor, Dark Blue = Fair, Green = Good, Yellow = Very Good and Red = Excellent

Transitional colors have been provided to show a 5,000 knot-feet transition between Poor to Fair and Fair to Good. Light purple represents the transition from Poor to Fair. Light blue represents the transition from Fair to Good.

Example: Max Ventilation Rate: This forecast represents two smaller areas of poor maximum ventilation (purple). One area exists within the upper Rio Grande Valley. The other poor rating area is found across the northeast and east central plains and is related to a back door cold front (red circle). Excellent ventilation ratings are forecast for western and central areas (colored red). Large gradients found in the graphic can be used to identify "ventilation watch out" days. There is a short distance between the Poor rating area (near Espanola) and the Excellent rating area (near Albuquerque). It is very possible that only 1 or 2 hours of Good to Very Good ratings exist within that transition zone.

Vent Window

Purpose: This graphic represents the number of hours ventilation rates are forecasted to be equal or greater to 40,000 knot-feet. Customers will be able to gauge the ventilation burn window better. The algorithm that produces this graphic reviews hourly ventilation rate forecasts between mid morning to late evening.

Example: The maximum ventilation rate (bottom graphic) was predicted to be Fair (blue color)-Good (green color) across portions of the northern and western mountains on December 1st, 2014. The state waiver would allow land agencies to burn under these conditions. After reviewing the Vent Window graphic (top), Fair-Good category was only expected for a few hours thus making a smaller ventilation burn window. A burner could have used this information as guidance to adjust their burn operations.

Max Ventilation Rate Trend

Purpose: This graphic shows the maximum ventilation rate trend from the previous day. It will allow burn managers to see decreases and increases of the ventilation rates across a larger spatial domain versus just looking at a point source. Land Agency customers like to identify trends in weather to keep situationally aware.

Example: MaxVentRateTrend: This particular graphic indicates significantly lower ventilation rates compared to the previous day March 18th 2013. A backdoor cold front was the culprit, especially impacting the eastern plains.

Max Ventilation Hour

Purpose: This graphic represents the projected time of maximum ventilation. Local time is used for the graphic. The algorithm that produces this graphic reviews hourly ventilation rate forecasts between mid morning to late evening so it won't account for the rare situations when max ventilation rate occurs during the early morning hours. 

Example: Max Ventilation Hour: This forecast represents the maximum ventilation time ranging between 14 (2 pm) to 17 (5 pm) mid February 2014. These times are normal for the time of year across northern and central New Mexico.

Max Transport Wind

Purpose: This graphic represents the maximum forecast transport wind (speed (knots)/direction) during the day period. It should be noted that the depicted wind speed and direction on this graphic may not coincide with Max Ventilation Rate and the Time of Max Ventilation. During most cases, Max Transport Wind and Max Ventilation Rate will occur during a similar time frame. Stronger transport wind (i.e. values greater than 20 knots) typically coincides with breezy to windy conditions. The algorithm that produces this graphic reviews hourly transport wind forecasts between mid morning to late evening.

Example: Max Transport Wind: This graphic depicts the maximum transport wind, both direction and speed, predicted for the day. Notice the distinct wind shift extending from near Raton to Clovis (circle red). The north/northeast wind direction represents a back door cold front. This graphic should be useful in showing the direction the smoke moves, especially during the afternoon period. Although in this case, the back door frontal push may have produced the strongest winds during the morning across the northeast so there are exceptions.

Max Mixing Height

Purpose: This graphic represents the maximum height of the mixed layer or the height a parcel of air would rise in the atmosphere from the surface.  Mixing heights are a direct link to determe stability of the atmosphere. An unstable atmosphere allows for deeper mixing and can allow fires to breathe more efficiently. This graphic shows maximum projected mixing height values for the day in feet above ground level (AGL) and reviews the hourly mixing height forecasts between mid morning to late evening. Some of the large fire growth events have been associated with deep mixing, especially above 15000 ft AGL.

Example: Max Mixing Height: This particular graphics shows deep mixing across northern and central New Mexico on June 11th 2013. Ongoing wildfires such as the Jaroso, Thompson Ridge and Silver were active on this day.

HYSPLIT

Purpose: HYSPLIT is a software program that ingests several types of weather models to create plume trajectories. The graphics found within this tab will display HYSPLIT trajectory forecasts for 22 pre-determined points overlaid on a scalable ESRI map.  Each trajectory will start from a point source indicated by a large star on the map. The triangle symbol indicates hourly air parcel (i.e smoke plume) positions along the plume trajectory. The plume trajectory is started 10 meters (around 30 feet) above the point source.  You can click on the triangle to view location (lat/long) and plume rise (meters) information of the air parcel. The model used to initialize HYSPLIT for this graphic is the RUC (Rapid Update Cycle). The RUC model has a spatial resolution of 20 km and a hourly temporal resolution out 12 hours in time. The graphics will update every hour around half past the hour.  An "on-demand" point-source feature for spot forecast requests (local-state-federal governments) will be added in the future. 

The graphics should be useful for determining the projected direction of a smoke plume from a point souce.  State and Federal burn bosses (prescribed burns) can use these graphics to keep situationally aware during a changing atmosphere. Public ag burners that cant request a spot forecast can monitor the closest point source and use the trajectories as guidance.  The graphics could also be useful during short-term hazardous spill emergencies.  Due to the course spatial resolution of the RUC model data, trajectory outputs may not take into account terrain impacts within the lower levels of the plume rise (i.e high mountain basins like the Moreno Valley).  Also keep in mind that the graphics are solely model based and not edited by a forecaster. They should serve as a guidance tool only.

Example: Overview trajectory graphic valid at 1 pm MST November 19th, 2014.  pre-set point (Pelon Mtn RAWS) near a prescribed burn. 

Note: 20z = 1 pm MST or 2pm MDT, 0z = 5 pm MST or 6 pm MDT, 12z = 5 am MST or 6 pm MDT

Close-up trajectory graphic valid at 20z or 1 pm MST Nov 19th for a pre-set point (Pelona Mtn RAWS location/near San Augustin Plain). 

A prescribed burn was found near the Pelona Mtn RAWS trajectory source point.