textproduct: Raleigh

WHAT HAS CHANGED

* Forecast solutions featuring a more progressive front pushing into and lingering over the Carolinas is becoming more likely; favoring more persistent cloud cover and more seasonable temperatures on Saturday, which could lingering into Sunday.

KEY MESSAGES

As of 100 AM Wednesday...

1) The chance for storms returns to the forecast late this week Friday and into early next week as a humid airmass returns.

DISCUSSION

As of 100 AM Wednesday...

KEY MESSAGE 1... The chance for storms returns to the forecast late this week Friday and into early next week as a humid airmass returns.

The anomalous upper ridge over the region is forecast to gradually shift west toward the southern Plains of the US late this week and weekend into the early part of next week. As that happens, west to northwest flow in the mid-upper levels will allow for a frontal system to approach Friday into Saturday. Moisture levels will correspondingly increase to well above seasonal normals with precipitable water values around 2 inches Friday and Friday night. These moisture levels are expected to remain elevated near the 90th percentile for mid-September in the 1.5 to 1.8 inch range through early next week.

Ensemble and deterministic guidance has shown a more progressive cold front on Friday compared to previous solutions, leading to an increase in storm chances late Friday into Friday night. The front is expected to drop in from the northeast, though perhaps stall out over the area Saturday before washing out sometime late this weekend Sunday. Shear profiles are quite unremarkable Friday, such that a severe threat is not expected at this point. But the boundary nearby will favor that isolated to scattered storm activity during peak heating.

From Sunday onward, ensemble guidance continues to show a potential unsettled pattern, albeit with low predictability, for afternoon and evening isolated/scattered storms. The pattern is not really conducive to widespread activity, but well above average moisture levels will promote this storm chance.

For temperatures, we end the week generally in the lower 90s, falling into mainly the mid 80s to around 90 through the remainder of the period. Dewpoints get soupy into the low 70s this weekend, resulting in an end to the comfortable humidity.

AVIATION /11Z WEDNESDAY THROUGH SUNDAY/

As of 630 AM Wednesday...

Prevailing VFR conditions are expected through the 24 hour TAF period. Mist lingering around RWI due to local effects is expected to persist until shortly after sunrise before dissipating. Otherwise light and variable winds with FEW afternoon cumulus around 4,000 ft is expected through the daylight hours. Brief east-southeast flow over the Coastal Plain tonight will increase crossover temperatures to around 60 degrees and may result in another round of mist, and perhaps periodic fog, around RWI into Thurs morning as surface conditions go calm.

Outlook: A risk of shallow, radiation fog/mist at RWI will continue for Fri morning. Widely scattered convection over wrn NC Thu afternoon may drift into the INT vicinity by early evening, followed by a better chance of convection along a passing cold front Friday afternoon-evening, especially over the Piedmont. Nely flow behind that front will increase the chances for IFR-MVFR ceilings Sat morning, lowest and most likely at INT/GSO.

RAH WATCHES/WARNINGS/ADVISORIES

None.