textproduct: Raleigh

WHAT HAS CHANGED

* The Flood Watch has expired for the northern Piedmont and nrn Coastal Plain.

KEY MESSAGES

As of 300 AM Friday...

1) Well below average temperatures in cold air damming will continue for the next couple of days and will be accompanied through tonight by additional waves of elevated convection and locally heavy rain.

2) By the end of the weekend, expect a return to more typical late July weather, with highs around 90 and mostly diurnally driven convection.

DISCUSSION

As of 300 AM Friday...

KEY MESSAGE 1... Well below average temperatures in cold air damming will continue for the next couple of days and will be accompanied through tonight by additional waves of elevated convection and locally heavy rain.

"Overrunning" lift/isentropic upglide, atop a surface frontal zone draped from far sern NC wswwd across the cntl Savannah Basin and TN Valley, will maintain widespread overcast and mixed character rain (ie. a combination of light rain/drizzle and embedded showers) through tonight and also support at least a couple of waves of deeper elevated convection and related locally heavy rain. The first wave of elevated convection will focus this morning over srn NC, where 925 mb WAA/isentropic ascent and elevated instability nearest the frontal zone to the south will be maximized. The second will be related to the approach and passage tonight of a mid-level shortwave perturbation approaching from MO. The latter feature may yield a couple of areas of concentrated, heavier rainfall amounts, including again across srn NC where MUCAPE and deep moisture will remain maximized, but also possibly over the nw Piedmont, where LPMM fields depict a secondary maximum. An extension in time of the Flood Watch that remains in effect for srn NC will be considered, as will the issuance of a new Watch for a portion of the nrn Piedmont later today should model and observational trends continue to suggest a secondary maximum may indeed result there.

It will otherwise remain unseasonably mild, with high temperatures around 10 F below average in the aforementioned CAD overcast and periods of rain; and the record low maximum temperature of 81 F today at FAY has a very realistic chance of being set.

KEY MESSAGE 2... By the end of the weekend, expect a return to more typical late July weather, with highs around 90 and mostly diurnally driven convection.

By Sunday, the front that has been around central North Carolina should have moved far south to have minimal impact locally, and highs should rebound into the 80s everywhere. By Monday, highs will return to more typical upper 80s and lower 90s, continuing through the week. Precipitation should also return to generally being diurnally-driven. While coverage should be isolated most days, the greatest coverage should occur Tuesday night into Wednesday with a boundary moving through the region.

AVIATION /06Z FRIDAY THROUGH TUESDAY/

As of 205 AM Friday...

In a regime of "overrunning" lift atop a frontal zone over cntl SC and sern NC, with a related warm season cold air damming airmass over cntl NC, current areas of MVFR ceilings across nrn NC to LIFR- IFR ones across srn NC are forecast to lower uniformly into IFR-LIFR during the next few hours, then only minimally lift today. While light rain will be possible areawide throughout the TAF period, elevated convection and related moderate to heavy rain and significant visibility restrictions are expected at FAY, RWI, and RDU at times, especially this morning. A second wave of convection will accompany the approach and passage of a mid-level disturbance this evening.

Outlook: Cold air damming and chances of rain and flight restrictions will continue through Sat, followed by a return to a more typical summertime pattern with diurnally-driven convection by early next week.

CLIMATE

Record Low Maximum Temperatures:

July 24: KFAY: 81/1985

RAH WATCHES/WARNINGS/ADVISORIES

Flood Watch until 9 AM EDT this morning for NCZ042-043-073>078- 083>086-088-089.