Key message 1, Arctic high pressure will remain dominant over ENC for the next few days. Below normal highs and lows are expected into next week with highs ranging from 30-45 degrees and lows around 15-30 degrees. Late night/early morning wind chills will be in the 10s to low 20s through the week. The coldest period in the forecast is currently Saturday night/Sunday morning with wind chills ranging from -5 to 10 degrees. Potentially record breaking cold temperatures will be possible Sunday, Monday, and Tuesday mornings.
key message 2, A deep positively tilted upper level trough will dig across the Plains later this week, becoming neutral to negatively tilted this weekend as it crosses the ECONUS. A southern stream shortwave originating from the Pacific northwest will track south and east across the Gulf states late this week and into this weekend while a northern stream shortwave will simultaneously dive into the SECONUS from the Hudson Bay. These features are forecast to result in surface cyclogenesis off the SE coast this weekend. If these shortwaves phase together, the low may rapidly intensify as it moves northeast near the coast of the Carolinas. If these shortwaves don't phase together, or phase together farther offshore, the low will be weaker and would not intensify as rapidly.
Precipitation may start as early as Friday night with snow across the coastal plain, a wintry mix along the coast, and rain along the OBX. All P-types are expected to change over to snow Saturday night and continue into Sunday morning. There's concern for reduced visibility from blowing snow given forecast gusts of 30-35 mph across the coastal plain and 40-50+ mph along the OBX.
The WPC Winter Storm Severity Index now shows a 60-80% chance of moderate impacts and a 40-50% chance of major impacts across ENC. How impactful this system will be will become clearer with future updates, so users should be leery of any deterministic snow total maps this far out. Snow totals vary greatly among the models, and with differences in the low's strength and track, it's too soon for accumulation specifics.
This powerful coastal storm will also coincide with a higher tide cycle, which will exacerbate potential coastal flooding impacts, especially along the OBX.
06z Wednesday through Sunday VFR conditions and clear skies are expected to continue through today as dry and cold high pressure persists over the region. Another dry boundary will move through tonight though winds remain light at less than 10 kt.
Outlook: VFR conditions will likely continue through Friday as cold high pressure remains in place. This weekend an extended period of sub-VFR conditions is likely as a coastal low develops and brings snow to most of Eastern NC.
Scas are in effect for the coastal waters and Pamlico Sound for NW winds gusting to 25-30+ kt and 4-6 ft seas. Conditions will improve around sunrise and winds will decrease to 10-15 kt as they back to the W today and seas subside to 2-3 ft. A dry cold front will cross the area tonight, causing winds to veer to the NW and increase to 15-25 kt with gusts to 25-30 kt across the coastal waters and Pamlico Sound. Seas will respond by building to 4-5 ft (6 ft near the Gulf Stream waters).
Outlook: SCA winds and seas will persist through early Thursday afternoon and then return Friday night. Conditions will continue to deteriorate through the weekend with Gales developing Saturday and increasing confidence in storm force gusts Saturday night through Sunday morning.
Nc, none. Marine, small craft advisory until 7 am EST this morning for amz135- 150-156-158. Small craft advisory until 8 am EST this morning for amz152- 154.
