textproduct: Raleigh

WHAT HAS CHANGED

* Above average uncertainty exists with timing and amounts from the next chance of rain: this weekend.

KEY MESSAGES

As of 245 AM Tuesday...

1) Well above average and unseasonably hot temperatures will develop this week and continue until a front wavers over the srn Middle Atlantic with a chance of rain this weekend.

A sub-tropical ridge will progress and strengthen across the South Atlantic states this week. The ridge will then lose influence this weekend, as a weakening, positively-tilted trough settles across the region ahead of a vigorous nrn stream trough forecast to amplify and pivot across the Great Lakes.

At the surface, a Canadian high now centered across the OH Valley and Great Lakes will progress across and offshore the Middle Atlantic through midweek, then to near Bermuda by Fri. Sly flow around the Bermuda high, and ahead of a wavy front that will settle into and probably waver over the srn Middle Atlantic this weekend, will contribute to warming temperatures through the week and to near/around 90 F by Thu and especially Fri.

While hotter, the pre-frontal airmass will not become particularly humid, with only modest low-level moisture characterized by surface dewpoints in the lwr-mid 60s forecast ahead of the front on Sat. When combined with weak mid-level lapse rates of generally less than 5.5 C/km, instability should remain weak and supportive of mostly scattered convection during the afternoon. A better chance of rain will result behind the front, probably later in the weekend for cntl NC, when and where sly and strengthening 850 mb flow will favor isentropic lift and rain. Some degree of cold air damming would also result, but uncertainty for this weekend remains regarding the frontal location, possible weak wave development along the front, and the extent of post-frontal CAD. Regardless, there is a consistent signal in model guidance for the front to move offshore by early Mon, with another Canadian high poised to build across much of the ern US early to mid next week.

DISCUSSION

As of 245 AM Tuesday...

KEY MESSAGE 1... Well above average and unseasonably hot temperatures will develop this week and continue until a front wavers over the srn Middle Atlantic with a chance of rain this weekend.

AVIATION /12Z TUESDAY THROUGH SATURDAY/

As of 645 AM Tuesday...

High confidence in overall VFR conditions persisting across central NC terminals, though a few areas over the Northern Coastal Plain could be MVFR temporary for a few hours this morning. Winds will remain light and variable with weak northerly flow throughout the period. Mid level cloudiness around 6,000 to 10,000 ft will continue across northern and eastern terminals, remaining well within VFR thresholds before gradually scattering out in the afternoon.

By late tonight early Wednesday morning another round of patchy fog/ low status could be possible especially at KRDU, KRWI and KFAY. Did not add to the 06Z TAF due to low confidence.

OUTLOOK: Predominantly VFR conditions are expected to hold through late week, with late night to early morning low stratus/fog remaining the main threat for sub VFR conditions during calm overnight windows. Rain and thunderstorm chances will gradually increase over the weekend, bringing the highest likelihood for widespread sub VFR conditions late weekend into early next week.

CLIMATE

Record High Temperatures:

September 30: KRDU: 89/1954

October 1: KGSO: 90/1986 KRDU: 90/1986

RAH WATCHES/WARNINGS/ADVISORIES

None.