textproduct: Raleigh

WHAT HAS CHANGED

As of 140 AM Friday...

* No major changes

KEY MESSAGES

As of 140 AM Friday...

1) There remains a threat of fog this morning over the northern Coastal Plain

2) Fire weather concerns will remain elevated through next week owing to extremely dry conditions, near record high temperatures and low relative humidity.

3) Near record warm temperatures possible Tue through Thu.

DISCUSSION

As of 140 AM Friday...

KEY MESSAGE 1... There remains a threat of fog this morning over the northern Coastal Plain

Model and ensemble guidance continue to indicate the potential for early morning fog over the northern Coastal Plain, roughly from Rocky Mount to Louisburg to Roanoke Rapids. Dewpoints in this area have risen into the middle 40s. This increased low-level moisture combined with excellent radiational cooling should continue to promote a fog threat this morning, mainly in the hours of 5 and 8 am. The latest HREF members appear to have backed off somewhat on the westward extent, with even the HRRR keeping most of the potential fog east of the Triangle. We will monitor observational trends through the night for a possible Dense Fog Advisory. Any fog should disperse and lift shortly after sunrise, with temperatures climbing well into the 70s to close out the work week.

KEY MESSAGE 2... Fire weather concerns will remain elevated through next week owing to extremely dry conditions, near record high temperatures and low relative humidity.

A strong upper ridge will build across the Southeast this weekend and then persist through next week. As the ridge builds, a shortwave trough will cross the Great Lakes on Saturday, with its associated weak cold front forecast to slip backdoor into northeast NC. There as subtle hints of some isolated showers in the Piedmont, mainly from the NAM owing to some weak and shallow instability, but the general consensus is that front will be dry and will be the only blip in building heat through next week. High pressure will shift offshore by Monday and winds are expected to turn to more southwesterly. The limiting factor for fire weather concerns this week has been weak winds, but as high pressure shifts offshore by Monday, winds are expected to turn to more southwesterly in a pattern more favorable for at least some slightly stronger winds, although guidance currently still suggests winds and gust below 20mph. Forecast soundings also indicate mixing that will keep RH values in the 20s and 30s most days, so fire weather parameters may have to monitored closely.

KEY MESSAGE 3... Near record warm temperatures possible Tue through Thu.

Mid-upper level ridging will steadily build over the Gulf and Southeast states through much of next week. Low level thicknesses will rise from 20-25 m above normal Mon to 40-50 m above normal by Wed/Thu, with Wed likely the hottest day. Temps are expected to be 15-20 degrees above normal Tue-Thu, within a category or so of records (see climate sections below). NWS Experimental Heat Risk reaches Level 2/Moderate/Orange by Tue/Wed, and this level of early- season heat could be dangerous, especially to those vulnerable to the heat. CPC outlooks extending beyond Thu suggest that temps are likely to stay much above normal into next weekend.

AVIATION /12Z FRIDAY THROUGH TUESDAY/

As of 605 AM Friday...

With the exception of RWI, there is high confidence of VFR conditions through the 24-hour TAF period. Patchy fog has developed in/near RWI. It is difficult to tell how extensive this fog may be, but based on satellite trends and crossover temperatures, kept the mention of LIFR conditions until 13-14z at RWI. We removed the MVFR tempo at RDU given the likelihood of reaching its crossover temperature much lower than earlier anticipated. Light winds of 5 kt or less are expected today and tonight.

Outlook: VFR should prevail most of Sat and Sun, though a backdoor cold front moving through Sat night could bring sub-VFR stratus over the Piedmont early Sun. VFR is expected Mon and Tue.

CLIMATE

Record High Temperatures:

April 11: KFAY: 90/2001

April 14: KGSO: 90/1922 KRDU: 91/1941 KFAY: 93/1922

April 15: KGSO: 90/2006 KRDU: 92/1941 KFAY: 95/2006

Record High Minimum Temperatures:

April 13: KGSO: 61/2019 KRDU: 66/1930

April 15: KGSO: 65/2006 KRDU: 64/1993

RAH WATCHES/WARNINGS/ADVISORIES

None.