Key MESSAGE 1, Strong but slow-moving cold front will approach the Carolinas today as disorganized shortwave energy over the Northern Plains phases over the Great Lakes and digs across the mid-Atlantic. Mid-level heights will remain well above average for late March (up to 1-2 sigma), with low level thicknesses supporting highs in the mid to upper 80s inland. This will threaten a few record highs - see the CLIMATE section for details.
KEY MESSAGE 2, Increased moisture advection along the southward-advancing frontal zone looks to support the next appreciable chance of showers and an isolated thunderstorm or two, focused mainly Friday night into Saturday with the best chances north of US Highway 70. Instability continues to look meager with less than 500 J/kg MLCAPE and rather stubborn convective inhibition, and the severe thunderstorm risk appears to be very low (less than 2%). Further inhibiting thunderstorm chances is the anafrontal nature of this boundary, with the bulk of precipitation expected to fall on the cooler, more stable side of the front. The HRRR does suggest a risk of a few thunderstorms developing just ahead of the front, but this is juxtaposed with a narrow corridor of uninhibited CAPE mainly west of our area. This will likely fall apart by the time it reaches ENC.
Overall moisture does not look to be deep enough to support significant rainfall, although several 12z models are showing higher QPF amounts to around a quarter inch with some HiRes models showing up to a half inch. Highest amount still appear to be across the northern tier.
KEY MESSAGE 3, Behind this front, another surge of northerly winds is expected tonight and Saturday, along with cooler, below normal temperatures returning over the weekend. There is a potential for frost Saturday night with latest NBM probs showing greater than 70 percent across inland counties, and north of 80 percent along and north of Highway 64.
KEY MESSAGE 4, A deep, and dry, northerly flow will develop across the Carolinas on Saturday, and is expected to RH values falling into the 20s. This will overlap with breezy conditions, leading to an increased fire danger for roughly the western half of ENC. In coordination with the NCFS, an Increased Fire Danger Statement (IFD) will be issued for Saturday to cover the this risk. Across the Outer Banks, the cool and more moist onshore flow off the Atlantic should limit the fire danger, and the IFD will not include those areas for now. Of note, portions of the IFD area could come close to critical fire concerns (ie. Red Flag Warning criteria). This may especially be the case if the winds end up higher and/or if the RH ends up lower.
18z Friday through Wednesday As of 18z/2pm, a cold front was stretched west to east across southern Virginia. Ahead of the front, gusty west to west- southwest winds were ongoing across ENC, and this will continue for several more hours. The front is then expected to move south across ENC this evening and tonight. See below for the expected timeframe for when the front will move through each TAF site.
PGV: 21-23z ISO: 23-01z EWN: 00-02z OAJ: 01-03z
Along and behind the front, there will be an increased risk of SHRA and sub-VFR CIGs. There is a high likelihood (>80% chance) of MVFR CIGs and a moderate (40-60% chance) of IFR CIGs. For now, then, I went with a prevailing MVFR group with SCT IFR- level clouds. Reductions to VIS will be possible as well, but the setup doesn't appear to favor significant reductions (ie. Only in the 4-6SM range). Gusty north to northeast winds will develop behind the front, with a sharp windshift expected along the front, itself. Wind gusts of 20-30kt will be common from this evening into the day Saturday.
Outlook: High pressure will move over the region this weekend, then shift offshore by next week. As the high shifts offshore, moisture return may support afternoon cumulus development along the seabreeze, with brief bouts of MVFR/low VFR CIGs.
Sw winds slowly increasing this morning around 15-20 kt and seas around 3-5 ft. Winds and seas will continue to build this morning into the afternoon with strengthening SW flow ahead of an approaching cold front. That boundary will push south across the waters late this afternoon and evening with a strong northerly surge developing behind the front. The strongest CAA will occur after midnight through much of Saturday when Gale Force conditions are possible with highest chances across the coastal waters and Pamlico Sound. Seas will build to 6-10+ ft peaking during the day Saturday.
Marine headlines were not changed from the previous forecast apart from minor timing adjustments over the Pamlico Sound. Upgrades to Gale Warnings may be needed this afternoon.
Outlook: Seas will likely remain elevated into at least Sunday. Mostly benign conditions expected for much of next week with high pressure centered off the coast.
Nc, none. Marine, small craft advisory until 8 pm EDT Saturday for amz131-230- 231. Small craft advisory until 4 am EDT Saturday for amz135-152- 154-156-158. Gale warning from 4 am to 6 pm EDT Saturday for amz135. Small craft advisory from 8 pm this evening to 8 pm EDT Saturday for amz136-137. Small craft advisory until 8 am EDT Saturday for amz150. Gale warning from 8 am to 4 pm EDT Saturday for amz150. Gale warning from 4 am to 8 pm EDT Saturday for amz152-154-156- 158.
