textproduct: Raleigh

WHAT HAS CHANGED

* Nothing appreciable

KEY MESSAGES

As of 300 AM Wednesday...

1) Much warmer, with Increased Fire Danger today

2) Warm and dry conditions are expected Thursday and Friday with a chance of showers and isolated thunderstorms returning Saturday. Higher chances of much needed rainfall expected late Monday or Tuesday and again mid-week.

DISCUSSION

As of 300 AM Wednesday...

KEY MESSAGE 1... Much warmer, with Increased Fire Danger today

A low amplitude mid-level trough in nwly flow aloft will progress into the cntl Appalachians this morning and across and offshore the Middle Atlantic through early tonight. At the surface, an accompanying frontal wave will track across and offshore the Middle Atlantic, with a trailing frontal zone that will likely extend from the Delmarva nwwd to the upr Great Lakes by 12Z Thu, and where it will continue to waver for the rest of the week. The front will be preceded by at least a couple of aggregate outflow boundaries maintained by weak, high-based convection from the OH Valley to the Virginias today.

To the south of the synoptic front and outflow, it will be unseasonably warm and very dry over cntl NC, with temperatures in the low-mid 80s F and with minimum RH in the upr teens to 25%. Wswly surface winds will also strengthen and become gusty with daytime heating, with sustained speeds generally 10-15 mph and with gusts in the 20s mph. An increased risk of wildfires and fire spread will result.

Some of the aforementioned weak, high-based convection, embedded within a band of 7-10 thousand ft AGL-based altocumulus, may drift across the ne Piedmont and nrn Coastal Plain this evening. The strongly-heated and deeply-mixed boundary layer will conditionally aid in strong, diabatically-cooled and accelerated wind gusts up to 40 mph under and near convection (from both evaporation and sublimation given that the freezing level will likely be just below LCL's/cloud bases), with generally Trace amounts expected should any precipitation overcome the sub-cloud layer and reach the surface.

KEY MESSAGE 2... Warm and dry conditions are expected Thursday and Friday with a chance of showers and isolated thunderstorms returning Saturday. Higher chances of much needed rainfall expected late Monday or Tuesday and again mid-week.

Warm and dry conditions are expected Thursday and Friday with a chance of showers and isolated thunderstorms returning Saturday. Higher chances of much needed rainfall expected late Monday or Tuesday and again mid-week.

A much needed increase in rainfall chances and reduction in temperatures appears within the weekend and next week forecast.

The overall pattern this week over NC will feature a general WNW flow aloft associated with ridging in the mid and upper levels, and a WSW surface flow with weak high pressure off the SE coast. It will not be as hot as in the past event has H5 heights remain in the 5700 to 5730m range. These heights are well below last weeks heat wave. It will also remain dry into Saturday morning as the low level moisture return is focused west of the Appalachians through that time. Our surface dew points are expected to range in the 45-55 range. Highs should top out in the lower to mid 80s Thursday and Friday.

Our first chance of much needed showers will come Saturday afternoon into Saturday night as a weakening cold front tries to slip south through the area Saturday afternoon and evening. Regardless, the instability appears lacking for organized thunderstorms over our region even with highs in the upper 70s to mid 80s SE. The dew points are forecast to remain in the 50s for the most part into Sunday. QPF appears rather light for this initial front.

Weak high pressure is then expected to build down the eastern seaboard Sunday into Monday. A progressive mid/upper trough should move from the Plains toward the eastern seaboard early next week. Again, the main focus for deep moisture return is forecast to possibly remain just to our west in the TN and OH Valley regions into the Appalachians with this progressively moving front. However, any wave development may change that for the area, so stay tuned on that potential.

This should be followed by additional and even better widespread rain chances mid to late week as the mean long wave trough tries to set up from the upper Midwest to the Mid-Atlantic in the longer term (mid week and beyond). The Gulf and Atlantic would be more in play and this should mean cooler and wetter conditions for our region then and beyond.

AVIATION /11Z WEDNESDAY THROUGH SUNDAY/

As of 640 AM Wednesday...

Wswly surface winds will strengthen and become gusty with daytime heating today, ahead of a disturbance aloft and related outflow boundaries maintained by weak, high-based convection from the OH Valley to the Virginias. Some of that weak convection, embedded within a band of 7-10 thousand ft AGL-based altocumulus atop a strongly-heated and deeply-mixed boundary layer, may drift into the vicinity of RWI with convective wind gusts to around 30-35 kts between 22Z-02Z.

Outlook: Increasing moisture into a frontal system that will move across the region on Sat will provide a chance of rain/showers and flight restrictions.

RAH WATCHES/WARNINGS/ADVISORIES

None.