Friday, July 01, 2016

NWS Mt. Holly Fire Weather Products Part 1 (part 3 of 5)

Recall that I live in the NWS Mt. Holly’s weather forecast area. I’d like to thank Lee Robertson, fire weather focal point for the National Weather Service (NWS), Mt. Holly NJ. Lee and I spent a few e-mails discussing the fire weather operations in NWS Mt. Holly. As you read my interview with Lee, please remember that fire weather operations in the NWS Mt. Holly are appropriate for the fire regime in the Mt. Holly Forecast Area. Further Mt. Holly’s Fire Weather Operations Plan is customized for their core audience (or partners). Mt. Holly Fire Weather Operations Plan that is available at under “additional fire weather information.”

This is part 1 of my interview with Lee Robertson, part 2 will post on Monday, July 4th.

Q1: Random Ramblings: I understand that NWS Mt. Holly’s Red Flag Warning Criteria, from the Mt. Holly Fire Weather Operations Plan, are as follows:

PA: wind >=20 mph (sustained/frequent gusts), Relative Humidity <=30%, 10 hour fuels <=10% 
NJ: wind >=20 mph (sustained/frequent gusts), Relative Humidity <=30%, 10 hour fuels <=10%
DE and MD: wind >=20 mph (sustained), Relative Humidity <=30%, 10 hour fuels <=8%

I have read the Mt. Holly Fire Weather Operations Plan. I understand that a Fire Weather Watch means that critical fire weather conditions (red flag warnings) may happen in the next 12 to 72 hours. Red flag warnings are issued by NWS office when critical fire weather conditions are imminent expecting to occur within the next 12 to 24 hours, The exact criteria vary from office to office.  I know that your fire weather plan uses other language to describe when you issue a Fire Weather Watch and Red Flag Warnings, but I want to use hours here because I think that this is language that everyone will recognize. Finally, you will sometimes issue a special weather statement for elevated fire risk. Can you elaborate on these fire weather products?

Lee: There really isn't much other way to describe Red Flag Warnings/Fire Weather Watch and their criteria.  Fire Weather Watches (PHLRFWPHL) are issued for the 2nd, 3rd or 4th 12 hour period of a forecast (24-48 hours). A Red Flag Warning (also PHLRFWPHL) is issued for the 1st or 2nd period of a forecast (12-24 hours).  The three criteria ALL have to be met at the same time to be considered a Red Flag Warning.  Some regions/offices have more or less criteria, but it's the same that all criteria have to be met.  If say, the Relative Humidity is not less than 30%, then it would not be a Red Flag Warning day even if winds gust to 30 mph and fuels are dry, and same for the other ones not being met.  You listed the criteria.  We forecast the RH (relative humidity) and Wind Speeds.  Fuel moisture is determined by our Forestry partners.  We coordinate with them to see who fuels have reacted to recent rainfall and drying conditions to determine of a RFW is needed.  Sometimes it is determined that fuels are not critically dry, or winds and/or RH will be marginal, and a RFW is not needed, so we may issue a Special Weather Statement to highlight the threat so people can be aware of the dangers of fires, and also give a heads up to our fire partners that it could be a dangerous day, but not critical RFW conditions.  We coordinate via a chat system with our neighboring NWS offices about the conditions we expect, and then coordinate with our Forestry partners our concerns for the day and determine what statements, if any, will be needed whether that be an RFW or SPS (Special Weather Statement) or a mentions in our Synopsis in our Forecast Discussion.

Q2. Random Ramblings: Who are Mt. Holly’s forestry partners? Do you have any idea how your forestry partners determine fuel moisture?

Lee: Yes, our partners are the Forestry/Forest Fire Services with each state.  
They have instruments in the field that give them actual measurements for fuel moisture.  But they also take into account recent rainfall and drying.

Q3. Random Ramblings: I know that the SPC does fire weather forecasts, can you briefly explain how Mt. Holly interfaces with SPC regarding forecast fire danger?

Lee: SPC does do a Fire Weather Forecast that covers the entire country.  They have specific criteria that they use to determine if they will issue an enhanced, critical, or extreme fire weather day.  You can view their criteria here. Again, we coordinate via our chat system concerns on either end.  There are days when they will have us in an outlook and our partners are less concerned due to fuels not as dry as thought, and there will be days when we have statements out when no outlook is in effect for various reasons, one being SPS uses Temperature as a criteria, while we do not.

Q4. Random Ramblings: How does Mt. Holly coordinate with adjoining office on fire weather forecasts. For example on March 23, 2016 (the day I first wrote Lee) Upton issued a special weather statement for elevated fire risk a couple of hours before you did. Did you talk to them?

Lee: As mentioned above, we have a chat system we use to coordinate with neighboring offices, or we use a phone call.

Other Articles in the series

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