textproduct: Raleigh

WHAT HAS CHANGED

As of 1224 PM Sunday...

* Overall snow chances have decreased this afternoon to early evening before precipitation band exits. Only a minor dusting at best is expected. * Black ice possible tonight but confidence is not great

KEY MESSAGES

As of 1224 PM Sunday...

1) Precipitation shield comes to an end early this evening, with potential black ice as lows drop into the mid to upper 20s. A brief 1-3 hr window on the tail end of the precipitation shield could mix with snow, but little to no accumulation is expected.

2) Cold arctic air expected early next week. Otherwise, two opportunities for precip in the long term period, but with low confidence at this point.

DISCUSSION

As of 1224 PM Sunday...

KEY MESSAGE 1... Precipitation shield comes to an end early this evening, with potential black ice as lows drop into the mid to upper 20s. A brief 1-3 hr window on the tail end of the precipitation shield could mix with snow, but little to no accumulation is expected.

We are now in the nowcasting phase of the precipitation event for the rest of today. A lot of the morning has been examining how observational trends are comparing to the global and regional models. Overall, observations have been running warmer than the colder and worst-case scenario model solutions. The HRRR and RAP have been most closely matching what has been observed so far, with the NAM-NEST and NAM too cold. In fact, the 12z NAM-NEST appears to be trending in line with the warmer solutions.

Observational analysis from the SPC Meso page, as well as radar dual- pol data and ACARS soundings, indicate that the freezing level is around 2 kft in the Triad, 3-4 kft in the Triangle, and 5-7 kft in the Coastal Plain, as of 12 pm. Surface temperatures are running upper 30s NW to mid 40s SE as of 12 pm. A gradual lowering of the freezing level is expected by later this afternoon to early evening, towards the end of the precipitation shield. This should allow for a brief 1-3 hr period where snow could mix in or briefly be all snow over the western and eastern Piedmont to the northeast Piedmont and northern Coastal Plain. However, there does appear to remain a warm layer just above the surface up until precipitation end time, if the HRRR still ends up verifying. Given that, any snow accumulation over the Triangle and points N and E appear to be very minimal, to a dusting at best, mainly on elevated and grassy surfaces. Snow potential will be very precipitation rate driven. If a heavy band can setup, a brief period of snow will be possible. This best potential should be between 2 and 6 pm.

Precipitation will come to an end early this evening, with temperatures falling into the low to middle 30s by later this evening. As for black ice potential, our confidence is not great. We do appear to maintain a weak southwest flow in the low-levels and the really cold air to our west over the TN valley and west of the mountains of NC may not fully reach us until later Mon night. Given that, we think low temperatures may not get as cold as previously thought. Forecast lows were adjusted up to the mid to upper 20s, but some HRRR/RAP data suggest we may stick in the upper 20s to near 30. Any lingering wet spots from the rain may turn into patchy black ice, but how extensive this may be is not clear. A Winter Weather Advisory or special weather statement may be needed later tonight after we assess trends in temperatures.

KEY MESSAGE 2... Monday, the region will be under weak mid/upper level troughing, with surface winds generally from the southwest. This will allow afternoon temperatures to rise into the 40s, generally 5 to 10 degrees below normal. Monday night, a reinforcing dry Arctic cold front will move through central North Carolina, further dropping low temperatures into the upper teens to low 20s.

Otherwise, the first opportunity for precip later in the week, albeit a very low probability for said precip...will come with a cold front on Thursday. The most recent models have been trending drier, so I wouldn't count on any precip for that period, at least at this point, thus the low probability. If there were to be precip, P-type could be a concern at least in our western zones at the very onset...but again, this is looking like a very low-risk chance.

The second opportunity could some either next weekend or early next week, but there are considerable differences in the models regarding timing and p-types. So for now, the low-end NBM PoPs during that time look reasonable. It's too soon to get into details about p- type given the wide differences among the various NWP solutions.

AVIATION /00Z MONDAY THROUGH FRIDAY/

As of 644 PM Sunday...

The primarily rain (with mixed snow) band has collapsed east of central NC this evening. KINT/KGSO just cleared out and this clearing should quickly trend eastward through the early overnight period. Expect VFR conditions to return at all TAF sites by ~03-04Z the latest. While the clouds will clear out, the near-sfc airmass will remain largely unchanged. High-res guidance continues to hint at the potential for fog in the Sandhills and near or at KFAY early Monday morning. Will maintain a TEMPO group for reduced visibilities from fog at KFAY to account for this possibility between ~08 and 12Z.

Otherwise, expect dry and VFR conditions Monday, with a little late morning wswly gustiness (15 to 20 kts) through the end of the TAF period. Flow will turn wnwly as a strong arctic front moves across central NC monday night. Some associated gustiness may accompany the passage of the front Monday night.

Outlook: Dry/VFR conditions are likely to hold through Thu, although a period of clouds and slight rain chances are possible Thu. Next chance for appreciable precipitation and potentially sub-VFR conditions will be this weekend.

RAH WATCHES/WARNINGS/ADVISORIES

None.