textproduct: Raleigh

WHAT HAS CHANGED

As of 107 PM Friday...

* Nothing appreciable.

KEY MESSAGES

As of 107 PM Friday...

1) Continued light patchy rain through this evening. Overcast with patchy dense fog possible tonight.

2) Low probability of wintry mix Mon into Tues morning in the Piedmont, but predominant precip type, and amounts remain uncertain.

DISCUSSION

As of 107 PM Friday...

KEY MESSAGE 1... Continued light patchy rain through this evening. Overcast with patchy dense fog possible tonight.

The sfc cold front remains stalled to our south this afternoon while cooler, saturated nely flow remains locked in over central NC. The steadier rain has moved well east of the Coastal Plain at this point following the exit of a lead vorticity perturbation. The strong short-wave/vort max has dug deep into GA/AL this afternoon, largely directing convection to our south into FL. Any lingering light patchy drizzle/rain over the area should dissipate with time through this evening. Otherwise, overcast conditions are expected again tonight for much of central NC with warm overnight lows lower to mid 40s. Similar to this morning, expect reduced visibility largely from elevated fog (lowered stratus) with perhaps some locally dense fog possible in areas. Best signal for dense fog appears to possibly be in the Foothills/Western Piedmont where some thinning of the clouds may result in radiational fog.

KEY MESSAGE 2... Low probability of wintry mix Mon into Tues morning in the Piedmont, but predominant precip type, and amounts remain uncertain.

Developing moist isentropic ascent atop the shallow sloped low/mid- level frontal boundary is expected to support light stratiform rain over the Mid-Atlantic, but timing and southern extent of the precipitation footprint remains uncertain and highly dependent on the evolution of mesoscale features (position and strength of 925- 850mb WAA/FGEN). The EPS has been consistently the northern most solution with precipitation directed over the Virginias, although its AIFS counterpart has shift slightly south compared to model runs from 12z Thurs. The GEPS/GEFS/AIGFS-ensemble remain farther south and paint highest probabilities of > 0.1" across the NC/VA border. Best chances 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. Unfortunately, predictability in these variables remains low for our area at this time to say much with any degree of certainty.

Most likely scenario: Minimal amounts of liquid equivalent with most places only achieving trace amounts to 0.05". 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): Onset of pure sleet Mon afternoon/evening results in very light sleet accumulation (abated a bit by warm ground and above freezing surface temps) transitions to light freezing rain after sunset when surface wet-bulb temps 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.

AVIATION /19Z FRIDAY THROUGH WEDNESDAY/

As of 145 PM Friday...

Steady rain has pushed to our east, but patchy light rain and drizzle will persist through the rest of this afternoon, mainly SE of INT/GSO, resulting in some MVFR visibilities. Otherwise, widespread IFR and locally LIFR ceilings will continue across central NC through this evening. There could be a period of MVFR ceilings late this afternoon and early this evening across our northernmost counties, with INT having the best chance out of our five TAF sites. Some brief clearing may also occur across the Piedmont this evening, best chance in the NW, which would favor fog development (locally dense) around INT and GSO late tonight and early Saturday morning. High-res guidance also shows potential for areas of fog advecting in from the east as NE low-level flow continues to bring in moisture off the Atlantic, so fog will be possible at the eastern TAF sites as well. Model soundings depict plenty of saturation in the lowest 1-2 kft, which may indicate more of a low stratus threat vs dense fog. Regardless, widespread LIFR ceilings are again expected across the region after about 06z, lifting to IFR then MVFR in the mid to late morning on Saturday. VFR conditions will spread in from NW to SE in the late morning and early afternoon as a more northerly wind shift filters in drier air and clearing begins to occur.

Outlook: Fog development will be possible on Sun morning, especially south and east, followed by another chance of flight restrictions, and mainly a cold light rain/drizzle in cold air damming, early next week.

RAH WATCHES/WARNINGS/ADVISORIES

None.