Day 4-8 Outlook
Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0351 AM CST Thu Jan 28 2021 Valid 311200Z - 051200Z ...DISCUSSION... Agreement/similarity in solutions amongst medium-range models only appears reasonable through Day 5 (Monday), in the most recent runs, as models continue to differ rather markedly with the evolution/advance of an eastern Pacific trough forecast to move onshore over the West late Day 5/early Day 6. These continued differences suggest ongoing lack of predictability within this evolving pattern, rendering any convective assessment largely meaningless beyond Day 5. Early in the period, an eastern U.S. upper trough will advance slowly toward the Appalachians Day 4 (Sunday), and then across the mountains early Monday, possibly then evolving into a closed low and subsequently drifting up the Northeast U.S. coastal vicinity. At the surface, a low-pressure system will take a similar eastward path across the eastern U.S., with a cold front -- trailing from an Ohio Valley low -- forecast to cross the Appalachians Day 4, before shifting offshore Day 5. However, a lack of warm-sector instability is expected, due to an insufficiently warm/moist boundary layer. Therefore, severe weather is not expected through Day 5.
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