textproduct: Raleigh

WHAT HAS CHANGED

* Marginal risk of severe storms through the late evening.

* We're under a Slight (level 2 of 4) risk of excessive rainfall for Sunday.

KEY MESSAGES

As of 800 PM Saturday...

1) A marginal risk of severe storms this evening.

2) On Sunday, excessive rainfall and a few strong to severe storms are possible through the afternoon and into the evening and early nighttime.

3) Widespread rain is expected Sunday night through Monday night, with some of the coolest high temperatures in more than a month.

4) Highs in the 90s return by Wednesday, severe weather chances return by Friday.

DISCUSSION

As of 800 PM Saturday...

KEY MESSAGE 1... A few strong to severe storms are possible this afternoon through this evening.

One MCV has passed to our east that produced some isolated wind damage this afternoon in Franklin and Johnston Counties in thunderstorms. An additional MCV is upstream over SW Virginia moving SE toward the region. Also, a cold front was located over northern VA. These features will keep the chance of storms going tonight and the front will stall Sunday keeping high POP for the region.

KEY MESSAGE 2... On Sunday, excessive rainfall and a few strong to severe storms are possible through the afternoon and into the evening and early nighttime.

A weak surface frontal zone will settle southward into NC tonight and stall out somewhere along the NC/SC border Sun, as the weak mid- upper low over KY and its shear axis extending across VA into the NW Atlantic settle slowly to the SSE. Ample moisture will be in place with PWs rising to ~120% of normal, and the influence of passing perturbations aloft (perhaps including a remnant MCV from today's convection from N AR to W TN) and the frontal presence to serve as a focus should allow for sct-numerous showers and storms, greatest across our S half. The 18z RAP shows a warm cloud depth exceeding 4 km Sun, favoring warm rain processes, and several models and modeling systems suggest a decent chance of locally heavy rain rates and rainfall, including the HREF's neighborhood prob of 1"/3 hrs of 70-90+% along and S of a line from INT to GSB, and the REFS's depiction of widespread 0.75-1.25" across much of our W and S. Despite our ongoing dry and drought conditions over the area, high rainfall rates can still yield flooding, esp in urban areas. Uncertainty regarding the location of greatest coverage preclude doing a flood watch at this time, but this will be monitored if the potential for multiple training and congealing cells increases.

KEY MESSAGE 3... Widespread rain is expected Sunday night through Monday night, with some of the coolest high temperatures in more than a month.

A cold front is forecast to move through North Carolina on Sunday, linger along the South Carolina/Georgia border Sunday night, then remain nearly stationary over Georgia for a couple of days. While some instability cannot be ruled out, since North Carolina will be on the cool side of the boundary, there will be less instability for the atmosphere to generate thunderstorms. In addition, with high pressure just off the mid-Atlantic states, northeasterly flow will bring some cooler air into the region. This certainly doesn't look like a true cold-air damming scenario, but with the forecast temperatures, it may feel like a CAD event is occurring - the forecast highs for Greensboro and RDU have not occurred since June 2. Regardless of the actual temperature, this will be a welcome relief to many considering how warm June and the start of July have been.

KEY MESSAGE 4... Highs in the 90s return by Wednesday, severe weather chances return by Friday.

Despite the respite from temperatures in the 90s early in the week, an upper level ridge will begin to build across the central United States in the middle of the week, pushing east into the end of the week. The raw GFS seems a bit overdone with temperatures, showing multiple days in the 100s, while the ECMWF is a bit more reasonable with highs in the mid 90s. Either way, temperatures will rise above normal once again, and with increasing humidity, the heat index will enter the triple digits.

In addition, the Storm Prediction Center has an area from Raleigh north into DC and northeast into Philadelphia outlooked for the potential of severe weather on Friday. It is rare for SPC to put an outlook in our area this many days out, but when they do, it usually verifies with some amount of severe weather. If this is the case, Thursday could end up being the hottest day out of the next seven, with lower temperatures on Friday due to thunderstorms.

AVIATION /00Z SUNDAY THROUGH WEDNESDAY/

As of 755 PM Saturday...

VFR conditions will dominate through 15z/Sunday. However, there is a chance of showers/storms at about 30 percent through the night at any one TAF site.

Looking beyond 18z Sun, the chance of showers and storms will increase Sunday into Sunday night. A NE flow is expected to develop Sunday and continue into Monday. Therefore, with the continued chance of showers/storms, there will be a lowering of overcast from MVFR to IFR and possibly some LIFR early Monday.

Rain chances will then dwindle for Tue-Thu with VFR conditions expected to prevail.

CLIMATE

Record High Temperatures:

July 11: KRDU: 99/1993

July 16: KGSO: 99/1915 KRDU: 101/1887 KFAY: 103/1937

July 17: KRDU: 100/1887 KFAY: 102/1932

Record High Minimum Temperatures:

July 11: KGSO: 75/1992 KRDU: 77/1981 KFAY: 77/2024

July 16: KGSO: 75/2024 KRDU: 78/2024 KFAY: 78/1992

July 17: KGSO: 75/2025 KRDU: 80/1887 KFAY: 77/2019

RAH WATCHES/WARNINGS/ADVISORIES

None.