Radar and Airborne Studies of Rainbands Associated with Fronts in the Pacific Northwest

Several case studies of mesoscale rainbands associated with cyclonic storms in the Pacific Northwest are described. In one case study the following bands were identified: A 15 km wide band which preceded the warm front (and traveled faster than it); two warm-sector bands 40 km in width which moved parallel to the cold front; a warm-sector band which extended across the cold front; a narrow, intense band on the cold front (which produced some of the highest precipitation rates); a broad band just behind the cold front; ripple-like bands (possibly associated with roll-clouds) normal to the cold front and superimposed upon the broad band; and, two bands about 350 km behind the cold front. In another case study an occluded frontal system produced a narrow, intense rainband at the front and numerous post-frontal bands, fifteen of which are described in this report. The apparent effects of orography on dissipating a portion of a rainband are described. Also presented are airborne measurements of particle sizes in a 70 km wide rainband associated with an occluded front.