textproduct: Raleigh

WHAT HAS CHANGED

As of 130 PM Wednesday...

* No major changes with the afternoon forecast update. Confidence remains high in widespread beneficial rainfall this weekend, although rainfall totals and areal coverage of > 1" remain uncertain.

KEY MESSAGES

As of 130 PM Wednesday...

1) Above-average temperatures are expected this afternoon with clearing skies northwest to southeast through the evening.

2) High confidence remains in steady light to moderate rain late Sat through Sun night. A period of beneficial rainfall appears likely for many locations in severe drought.

DISCUSSION

As of 130 PM Wednesday...

KEY MESSAGE 1... Above-average temperatures are expected this afternoon with clearing skies northwest to southeast through the evening.

As the cold front crosses the region early this afternoon, isolated showers are beginning to taper off across the southeast. Skies are beginning to clear on the back side of the front as much drier air will move in, and humidity levels will drop quickly. Despite the front, temperatures will remain well above normal today and tonight, with highs reaching the low to mid 60s. Winds will be northwest and become gusty at times with 25-20mph gusts this afternoon diminishing after sunset. Cooler air will arrive tonight as high pressure builds in. Temperatures will fall into the 30s overnight, with a few colder spots in the upper 20s.

KEY MESSAGE 2... High confidence remains in steady light to moderate rain late Sat through Sun night. A period of beneficial rainfall appears likely for many locations in severe drought.

An initially closed southern stream mid/upper level trough off the CA coast will kick eastward Fri and is expected to shift across the Southeast and southern Mid-Atlantic this weekend. NWP guidance is beginning to narrow in on the track the southern stream wave, but the mesoscale details remain less certain and will be directly tied to the location/magnitude of the maximum/minimum rainfall footprint. The biggest change in the past 24 hours is the expected placement of the surface high relatively to the incoming southern stream wave. Latest forecast suggest less mid/upper level confluence over the Northeast and results in the surface high to take a much farther south track over the Mid-Atlantic Sat morning and shift quickly off the Carolina coast by Sat evening. This will favor an exclusively in-situ CAD type, where diabatic processes are required to develop the CAD pattern as precip falls into a drier airmass.

Regardless of phasing concerns with the northern stream wave, central NC is favorably placed with respect to the southern stream wave and results in a variety of forcing mechanisms to lift anomalous deep-layer moisture advecting into the region. Probabilities of > 1" in 24 hours has more-or-less remained the same across the forecast area and range generally from 50-20%, with greatest probabilities across the Foothills and western Piedmont and least in the Coastal Plain. Reasonably high-end totals still range from 1-2 inches, which is slightly more favored from the Foothills into the Piedmont.

Alternate scenarios: Guidance is beginning to narrow in on the track of the southern stream wave, but the timing of its eastward translation remains the biggest forecast uncertainty. The 00-06z GEFS runs appear to the be the slowest, and using cluster analysis, this scenario has some support from some EPS members and results in the second most reasonable scenario that precip may not spread into the area until Sun afternoon. However, this scenario may be becoming less likely as the 12z GEFS is coming in more in line with other ensemble solutions.

AVIATION /00Z THURSDAY THROUGH MONDAY/

As of 838 PM Wednesday...

24 hour TAF period: VFR conditions will persist through the 24 hr TAF period. Expect light winds to stay a bit stirred overnight in addition to scattered mid to high level cloudiness at times. A lingering low-level jet may promote a period of marginal LLWS, but given the lower-level stirring and just overall low confidence in meeting criteria, decided to leave it out of this TAF package.

Light nwly sfc flow will pick up a bit late Thursday morning with gusts of up to 20 kts possible through the end of the 24 hr TAF period.

Outlook: The next chance for precipitation and sub-VFR conditions will be Sat night/Sun, otherwise expect dry weather and VFR conditions to prevail.

RAH WATCHES/WARNINGS/ADVISORIES

None.