Strategies to Improve Radiation Fog Forecasting at Elmira, NY (KELM) Robert Mundschenk, Michael Evans, Michael L. Jurewicz, Sr., and Ron Murphy – WFO Binghamton, NY Aviation Sub-Regional Workshop September 16, 2008

Outline Motivation Motivation Methodology Methodology Study Results Study Results A New Forecaster Tool A New Forecaster Tool Summary Summary

Motivation for Research KELM experiences radiation fog frequently with resultant IFR / LIFR / VLIFR conditions KELM experiences radiation fog frequently with resultant IFR / LIFR / VLIFR conditions Historically, this has been a challenging site for aviation forecasters Historically, this has been a challenging site for aviation forecasters –Unexpected dense fog development –Overly pessimistic forecasts (lighter fog than expected)

Favorable Location for Fog KELM Chemung River Valley

Methodology Fog Season - April 1 st through November 1 st Fog Season - April 1 st through November 1 st Compile a list of dates with clear skies and light winds Compile a list of dates with clear skies and light winds –3 Full Seasons worth of data ( ) Minimum observed visibilities and time durations of IFR conditions were tabulated Minimum observed visibilities and time durations of IFR conditions were tabulated –Many parameters thought to be pertinent to fog formation were tabulated NAM Boundary layer wind, lapse rate and RH forecasts NAM Boundary layer wind, lapse rate and RH forecasts Observed minimum temperatures Observed minimum temperatures Observed Cross-over temperature Observed Cross-over temperature Observed Chemung River temperatures Observed Chemung River temperatures Amount of recent rainfall, if any Amount of recent rainfall, if any Time of year (month) Time of year (month)

Results Most reliable indicators of low visibilities (dense fog): Most reliable indicators of low visibilities (dense fog): Light wind speeds (< 13 kts) around 950 mb (700 feet AGL) from NAM BUFKIT soundings Light wind speeds (< 13 kts) around 950 mb (700 feet AGL) from NAM BUFKIT soundings Overnight low temperature colder than the cross-over temperature Overnight low temperature colder than the cross-over temperature Large differences between the observed Chemung River temperatures and the minimum air temperature (air temperature at least 20 degree F colder than the river temperature). Large differences between the observed Chemung River temperatures and the minimum air temperature (air temperature at least 20 degree F colder than the river temperature). Heavy rain during the period 4 to 10 days prior to the event in question Heavy rain during the period 4 to 10 days prior to the event in question Model low-level RH and lapse rate correlated weakly with fog occurrence Model low-level RH and lapse rate correlated weakly with fog occurrence

Composite MSLP for Dense Fog Cases at 0600 UTC

Composite MSLP for Lighter Fog Cases (BR) at 0600 UTC

Composite 850 mb for Dense Fog Cases at 0600 UTC

Composite 850 mb for Lighter Fog Cases (BR) at 0600 UTC

A New Forecaster Tool Based on study results, a “pattern recognition” tool was developed Based on study results, a “pattern recognition” tool was developed –Data inputs from BUFKIT soundings, observed data and forecaster input –Help forecasters better differentiate between favorable and unfavorable nights for fog formation –Provides links to past events that most closely match the set of expected conditions

A New Forecaster Tool

Final Thoughts This tool allows forecasters to use pattern recognition to forecast fog This tool allows forecasters to use pattern recognition to forecast fog The tool promotes a probabilistic approach to fog forecasting The tool promotes a probabilistic approach to fog forecasting Similar tools can be developed for other TAF sites Similar tools can be developed for other TAF sites Verification will be done next summer Verification will be done next summer We still need to know more about what parameters can help us to forecast fog We still need to know more about what parameters can help us to forecast fog