Abstract:

 Crosswind, ceiling, and visibility constrain Southern California aviation, but forecast guidance covers one airfield and one variable at a time, leaving no quantified regional picture. METAR observations from 53 ASOS and AWOS stations (2006 to 2025, 10,403,137records) were paired with FAA NASR runway headings to resolve crosswind trigonometrically, then reduced to lagged conditional probabilities for all ordered station pairs, stratified by wind direction, season, month, and time of day. The domain packs dozens of civilian and military airfields across varied terrain. Calm wind, not wind direction, dominates inland low-visibility conditions, where rates run three to four times the directional-wind rate. Crosswind co-occurrence is strongest among coastal fields, while ceiling and visibility co-occurrence tracks shared elevation and terrain rather than distance.

The results presented are from the NOAA EPP CSC NERTO graduate internship project conducted under the mentorship of Ivory Small, National Weather Service, San Diego Weather Forecast Office. This NERTO experience aligns with the NOAA Cooperative Science Center in CESSRST-II, supporting the Center’s goal of conducting NOAA mission-aligned collaborative research to understand and predict changes in weather and atmosphere. This project, titled HAWCI-Hybrid Aviation Weather Climate Interface, addressed the research question: how often do Southern California airfields exceed operational crosswind, ceiling, and visibility thresholds, and which other airfields follow, and after how long? The work provides value to the scientific community and program stakeholders by converting two decades of routine observations into a quantified regional climatology and a standalone operational tool. Through this internship, the student deepened their understanding of NOAA mission areas and gained enhanced skills in large-scale data pipeline development, Python programming, spatial statistics, and operational software delivery.