11PM Day 1 Convective Outlook for Sunday, January 4. NO SEVERE THUNDERSTORM AREAS FORECAST
SUMMARY
Widely scattered, generally weak, thunderstorm activity is possible today across parts of central California and the Pacific Northwest into portions of the Great Basin.
Discussion
Mid-level troughing, digging into and through the northern Mid Atlantic and Northeast early today, is forecast to quickly turn eastward offshore and across the Canadian Maritimes through the remainder of the period, trailed by a more modest perturbation digging across the Florida peninsula and Bahamas vicinity. A broadly confluent mid-level regime in its wake is forecast to support the eastward progression of cool surface ridging into and across the Atlantic Seaboard, with perhaps some further southward advancement of the weakening leading edge of the cold air possible across the southern Florida peninsula and central through southwestern Gulf Basin.
While mid/upper ridging is likely to be maintained across much of interior North America, it appears that it will gradually lose amplitude as a number of smaller-scale perturbations, emerging from splitting large-scale troughing near the Pacific coast, progress through it. Across the eastern Pacific into western North America, models generally indicate that one weakening short wave impulse will accelerate inland across the central California coast and Sierra Nevada during the day, trailed inland by a somewhat stronger, but weakening, perturbation across the Pacific Northwest and Cascades, in advance of a sharply digging perturbation across the mid-latitude eastern Pacific.
Pacific Coast into Intermountain West
Mid-level cooling and forcing for ascent overspreading the region today through tonight probably will contribute to the evolution of thermodynamic profiles occasionally becoming at least marginally conducive to widely scattered convective development capable of producing lightning.
Southern Florida
Mid-level cooling and forcing for ascent, associated with the digging short wave trough, might contribute to sufficient destabilization for an isolated brief thunderstorm or two, mainly across the interior southern peninsula through southeast coastal areas late this afternoon.