11AM Day 2 Convective Outlook RESENT 1 for Friday, January 30. NO THUNDERSTORM AREAS FORECAST
SUMMARY
Thunderstorm probabilities across the U.S. for Friday through Friday night appear less than 10 percent.
Discussion
There appears little change from prior model runs concerning the general mid/upper flow evolution through this period. A lower latitude blocking regime may become a bit more prominent near/offshore of southern California and the Baja California Peninsula, with larger-scale ridging being maintained within the primary belt of westerlies across the Pacific coast through Rockies. This is forecast to include short wave ridging building along the British Columbia coast, in the wake of a short wave trough progressing inland across the Canadian and adjacent northern U.S. Rockies, and downstream of a large upper trough and broad/deep cyclone migrating northeastward across the eastern mid-latitude Pacific.
Downstream, several short wave perturbations, including one vigorous digging impulse (emanating from the Hudson Bay vicinity), are forecast to consolidate into amplifying, positively tilted larger-scale troughing encompassing much of the lower Mississippi Valley and Gulf Basin through southern Atlantic Seaboard by late Friday night. It still appears that this will be accompanied by only weak surface frontal wave development along a strengthening low-level baroclinic zone across the northeastern Gulf Basin during the day Friday. There appears to be better consensus among the various models concerning modest cyclogenesis initiating along the same frontal zone offshore of the Carolina coast, and along a remnant surface frontal zone across and northeast of the Bahamas, by late Friday night.
Pacific Northwest
In the wake of a weak inland advancing frontal precipitation band, models indicate that a modest mid-level cold pool will overspread coastal areas during the day Friday. However, forecast soundings indicate that this will not lead to boundary-layer destabilization supportive of an appreciable risk for convection capable of producing lightning.
South Atlantic Seaboard
Both NAM and Rapid Refresh forecast soundings suggest that some further boundary-layer moistening is possible near southeastern Florida coastal areas and parts of the Keys, where near-surface flow may maintain an easterly component into the day Friday. It is possible that this may contribute conditionally unstable thermodynamic profiles in the lower- to mid-troposphere, which could become supportive of scattered showers. However, it still appears probable that a substantive warm/dry layer further aloft will suppress thunderstorm development, before the boundary-layer stabilizes in response to cooling/drying, as near-surface winds back to north/northwesterly.
Otherwise, through at least this period, it appears that destabilization supportive of thunderstorm development, associated with the developing low offshore of the Carolina coast, will remain focused near the Gulf Stream.