AWUS01 KWNH 161930 FFGMPD CAZ000-170130- Mesoscale Precipitation Discussion 0021 NWS Weather Prediction Center College Park MD 228 PM EST Mon Feb 16 2026 Areas affected...Southern California... Concerning...Heavy rainfall...Flash flooding possible Valid 161930Z - 170130Z SUMMARY...Progressive cold front with strong pre-frontal southerly moisture flux will continue to shift eastward into the eastern Transverse and Peninsular Ranges through this evening. Less orthogonal ascent along terrain will reduce rainfall totals but intense sub-hourly totals up to 1" that may cause urban flooding and issues in and downstream of recent burn scars. DISCUSSION...RADAR and GOES-W visible imagery show a narrow band of intense showers/weak convective cores exiting Ventura county into S Los Angeles county extending southward through the eastern Channel Islands and starting to approach the southward turn of the coast across Orange and San Diego counties. Very strong moisture flux of 40-50kts of 925-850mb flow and steadily increasing moisture per CIRA LPW nearing .75" in that layer. Veering post frontal flow continues to be stark, with directional convergence remains between 75-90 degrees. Given the strength over 30kts (up to 50kts), it will continue to result in strong moisture flux for the convective elements supporting hourly rates of .75-1". This will continue what has been have observed moving through southward facing terrain of the Transverse Range including the Santa Monica Range, where totals of 2-3+" have been observed resulting in localized flash flooding. The strength of flow even below 850mb will continue to intersect the San Gabriel and San Bernardino Ranges lower to mid slopes with similar rates near .75-1"/hr though highest peaks will start converting over to moderate/heavy snowfall. However, with reducing southerly fetch, the Peninsular Ranges will see a quick pick up, but with less orthogonal convergence/orographic ascent will also see diminishing rates and therefore totals between 22-00z tonight. The lack of moisture flux off the California Bight will also reduce the effective ascent through the TROWAL further back west across the central Transverse Ranges where lighter rain will continue to slowly add to the totals through 00z as well. With the loss of orographic ascent/convergence and deeper moisture availability, rates will reduce but increased westerly flow and steepening lapse rates aloft before the main cold front will allow for a few rounds of scattered upslope showers with .1-.25"/hr rates/totals adding to the initial mainline. Still, the overall risk for flash flooding will be limited to urban and recent burn scars east and South of the LA Basin. Gallina ...Please see www.wpc.ncep.noaa.gov for graphic product... ATTN...WFO...LOX...SGX... ATTN...RFC...RSA...NWC... LAT...LON 34701850 34251725 33811664 32841626 32471628 32451709 32971743 33471782 33621834 33831850 33981871 34221933 34601910