FXUS62 KRAH 191020 AFDRAH Area Forecast Discussion National Weather Service Raleigh NC 620 AM EDT Thu Mar 19 2026 .WHAT HAS CHANGED... As of 115 AM Thursday... * Updated details on timing and characterization of Monday's cold front. && .KEY MESSAGES... As of 115 AM Thursday... 1) A chance of showers and storms will exist with the passage of a polar front next Monday, with a following risk of frost/light freezing conditions in continental Polar high pressure next Tue-Tue night. && .DISCUSSION... As of 115 AM Thursday... KEY MESSAGE 1... A chance of showers and storms will exist with the passage of a polar cold front next Monday, with a following risk of frost/light freezing conditions in continental Polar high pressure next Tue-Tue night. There is strong model agreement that the mid/upr-level pattern will become less-amplified and quasi-zonal across the mid- latitudes through the weekend, as the record-breaking sub- tropical high over the Southwest and SoCal breaks down. Within that developing fast/ quasi-zonal flow regime, a shortwave trough will progress from the nern N. Pacific inland and across the International Border vicinity through the weekend, then modestly amplify from the Great Lakes to the Northeast early next week - though both deterministic and ensemble model spread is high regarding the timing and amplitude of that feature, not surprising given the fast, quasi-zonal nature of the flow. Deterministic guidance is generally faster than ensemble means, with the latter favored by WPC. Also noteworthy within that wnw flow regime is that an elevated mixed layer from the nrn and cntl Rockies will likely be advected across the srn Middle Atlantic and Carolinas Sun night and Mon. At the surface, an expansive, continental-sourced high now extending throughout the Middle and South Atlantic states will be centered over the FL peninsula and adjacent Gulf and swrn Atlantic Basins through the weekend. The location and expanse of the high will limit moisture advection ahead of and into a polar front that will most likely move across cntl NC on Mon. The preferred slower timing of the parent shortwave trough noted above, and also the fast bias of models advecting cP air east of the Appalachians, suggest temperatures on Mon will continue well above average. Despite the warm temperatures, the aforementioned limited moisture return ahead of the front will likely yield surface dewpoints in the 50s F, to perhaps around 60 F in the Sandhills and srn-cntl Coastal Plain. Related buoyancy will be limited/weak, and possibly capped to deep convection by the EML with nwwd extent/away from the relatively richest low-level moisture (ie. ~60F surface dewpoints). So while the fast wnwly flow/shear profiles and the presence of the EML would both provide a conditionally supportive environment for severe convection, the relative lack of low-level moisture and buoyancy should mitigate that potential, even as predictability increases with time. It will turn markedly cooler and below average once again behind the cold front through the middle of next week, under the influence of cP high pressure that will weaken/modify while migrating from the nrn Plains to the Middle Atlantic. Low temperatures will likely be supportive of frost/light freezing conditions and a category or two colder than NBM/official forecast ones, which at present depict mostly upr 30s-lwr 40s. && .AVIATION /11Z THURSDAY THROUGH MONDAY/... As of 620 AM Thursday... VFR conditions prevail with light and variable surface winds this morning becoming northwest to westerly by this afternoon. Outlook: VFR conditions likely to prevail through the outlook period with overall light and variable winds. An area of decaying light rain will be possible early Sat morning (most probable at RDU and RWI with a 20% chance), but sub-VFR conditions are unlikely at this time. Southwest winds increase this weekend and may become gusty at times ahead of and especially behind a strong cold frontal passage and wind shift on Mon; showers and isolated storms may accompany the fropa. && .RAH WATCHES/WARNINGS/ADVISORIES... None. && $$ DISCUSSION...MWS AVIATION...AS