textproduct: Raleigh

WHAT HAS CHANGED

As of 211 PM Saturday...

* Monday's system has trended towards more of a cold rain Monday afternoon through Tuesday morning, but a period of wintry mix remains possible mainly north of I-85.

KEY MESSAGES

As of 212 PM Saturday...

1) Areas of dense fog possible tonight mainly across the southern Piedmont, Sandhills, and Southern Coastal Plain. A backdoor cold front will bring a chance of showers across eastern areas Sunday evening along with gusty post-frontal winds through early Sunday night.

2) Predominantly cold rain Monday afternoon through Tuesday morning, but a period of wintry mix remains possible north of I-85 corridor and northern Coastal Plain.

3) Well-above normal temperatures and near record breaking warmth expected late week into the weekend.

DISCUSSION

As of 212 PM Saturday...

KEY MESSAGE 1... Areas of dense fog possible tonight mainly across the southern Piedmont, Sandhills, and Southern Coastal Plain. A backdoor cold front will bring a chance of showers across eastern areas Sunday evening along with gusty post-frontal winds through early Sunday night.

Nwly sfc flow remains over central NC this afternoon as lingering low-level clouds continue to scatter out across the western/southern Piedmont. As clouds scatter expect temps to rise up into the lower 60s this afternoon. Skies should remain relatively clear tonight with calm winds expected. Sfc dew points are expected to remain in the mid 40s tonight. Given the clear skies and calm winds, areas of dense fog appear possible with best chances likely across the southern Piedmont/Sandhills/Coastal Plain. Forecast soundings in these areas indicate hourly temperatures several degrees below forecasted crossover temperatures. Ensemble probabilities for dense fog also peak in this vicinity. Elsewhere, expect patchy dense fog.

Any lingering fog Sunday morning should largely dissipate by ~14Z. After a warm afternoon with light sswly flow, a backdoor cold front will pass through central NC Sunday evening. Associated convection may accompany the passage, with shower chances highest along and east of the I-95 corridor. Some guidance suggests upwards of 500 J/kg of SBCAPE ahead of the frontal passage. As such, can't rule out a crack of thunder Sunday evening. Lastly, post-frontal gusts of up to 25+ mph will be possible lingering some into the overnight period. Overnight lows in the mid to upper 30s are likely.

KEY MESSAGE 2... Predominantly cold rain Monday afternoon through Tuesday morning, but a period of wintry mix remains possible north of I-85 corridor and northern Coastal Plain.

Developing moist isentropic ascent atop the shallow sloped low/mid- level frontal boundary is expected to support light stratiform rain over the Mid-Atlantic. The EPS/AIFS have been consistently the northern most solutions with the precipitation swath directed over the Virginias. Conversely, the GEPS/GEFS/AIGFS-ensemble remain farther south and paint highest probabilities of > 0.1" from the NC/VA border into central VA. Best chances for accumulating precip (liquid equivalent) will likely be along and north of the I-85 corridor into the northern Coastal Plain.

Using top-down and nomogram techniques for expected p-type, the overwhelming model consensus is that the 850-700mb layer is expected to remain > 155dam over NC and likely will not support anything other than sleet, freezing rain, or cold rain. The surface wet-bulb zero line and strength of the warm nose will likely determine predominant p-type over our area. Confidence is increasing that the true Arctic airmass, and single digit dew points, will remain in the northern Mid-Atlantic with much more marginal dew points in the upper 20s to low 30s in central NC. This will be much less favorable for any impactful wintry precip in our area.

Most likely scenario: Minimal amounts of liquid equivalent with most places only achieving trace amounts to 0.1". Light rain and conversational onset of some sleet Mon afternoon/evening ends as a cold light rain with surface temperatures above freezing throughout Mon night into Tues morning. No hazardous weather or impacts to travel expected.

Worst-case scenario (5-10% chance): A period of pure sleet Mon afternoon/evening near the NC/VA border may result in very light sleet accumulation (unlikely to accumulated on roadways due to warm ground and above freezing surface temps) transitions to light freezing rain after sunset when surface wet-bulb temps may drop below freezing. Even in this scenario freezing rain accrual will almost certainly be less efficient than a 1:1 ratio since air temps will likely be > 28 degrees. Minor impacts to travel for Tues morning commute would be possible due to a light/thin glaze on elevated surfaces and bridges. South of the northern tier of counties, only a cold rain is possible with surface temps well above freezing.

KEY MESSAGE 3... Well-above normal temperatures and near record breaking warmth expected late week into the weekend.

An unseasonably strong and deep ridge is expected to develop over the East Coast by midweek, but will become more amplified as a trough dives south through the Four Corners Region late week into the weekend. The mid/upper level pattern along with a deep layer of unseasonably warm temperatures in the lowest 500mb of the troposphere will favor well above normal temperatures to near record breaking warmth Fri into the weekend. During this time, highs eclipsing 80 degrees become likely, especially from the Triangle south and east. Temperatures in the mid 70s to around 80 would likely result in minor heat-related impacts primarily to individuals extremely sensitive to heat and without cooling/hydration. Please see climate section below for daily records.

AVIATION /19Z SATURDAY THROUGH THURSDAY/

As of 155 PM Saturday...

24-hour TAF period: An area of IFR to low MVFR stratus stretching over parts of the northern and western Piedmont and western Sandhills will continue to get eroded through this afternoon as weak high pressure builds in. Clearing and VFR conditions are now reported at all TAF sites with the exception of GSO which should also clear out in the next hour or so. VFR conditions will return to all of central NC by ~21z and persist through this evening. NAM, RAP and HRRR soundings depict the classic "inverted V" shape for fog development, locally dense, late tonight and early Sunday morning. Clear skies and mostly calm winds support this potential as well. Based on the crossover method and high-res guidance like the 12z HRRR, the best chance for fog is at the eastern TAF sites (RDU, FAY and RWI), but it can't be ruled out at INT and GSO either. So introduced TEMPO groups for this potential at all TAF sites. Any fog will quickly disperse by mid morning. Winds will be out of the W/SW tomorrow but remain around 7 kts or less.

Looking beyond 18z Sun: A backdoor cold front will bring a chance of showers and sub-VFR conditions on Sunday evening, especially in the east. Gusty NE winds will also be possible. Light precipitation and sub-VFR conditions are then expected on Monday and Tuesday. While the precipitation type will be rain in most places, a light wintry mix is possible in the far north near the VA border. Dry weather and VFR conditions should return on Wednesday.

CLIMATE

Record High Temperatures:

March 1: KGSO: 77/2012

March 6: KGSO: 78/2022 KRDU: 82/1967 KFAY: 86/1918

Record High Minimum Temperatures:

March 6: KGSO: 64/1967 KRDU: 64/1967 KFAY: 65/1961

RAH WATCHES/WARNINGS/ADVISORIES

None.