textproduct: Raleigh

WHAT HAS CHANGED

* A heat advisory has been issued for all counties Friday * The risk for severe weather has increased on Friday

KEY MESSAGES

As of 245 PM Thursday...

1) Much above normal temperatures Thursday and Friday afternoons, with a slight decrease in heat over the weekend.

2) Potential for strong to severe thunderstorms both Thursday and Friday afternoons, with greater coverage to the north.

3) Afternoon and evening thunderstorm chances will continue each day Saturday into the middle of next week.

DISCUSSION

As of 300 AM Thursday...

KEY MESSAGE 1... Much above normal temperatures Thursday and Friday afternoons, with a slight decrease in heat over the weekend.

A lack of cloud cover allowed for temperatures to rise rapidly today, and the development of some diurnal cumulus has only slowed the rise this afternoon. Isolated locations are likely to reach 100 degrees this afternoon, and a heat advisory remains in effect for much of the forecast area through 8pm tonight. No location is expected to fall below 70 tonight, with Raleigh and Fayetteville likely to only drop into the mid 70s. High temperatures will climb another few degrees tomorrow, and considering dewpoints should be similar, upper 60s to 70, that will bring nearly all locations to the Major category (level 3 of 4) of experimental Heat Risk. That indicates that significant adverse health impacts are possible for all populations without adequate cooling or hydration, and heat illnesses may develop suddenly for those working or exercising outdoors during the hottest part of the day. Will issue another heat advisory for Friday, this time for the entire forecast area. High temperatures should drop a couple degrees for the weekend.

KEY MESSAGE 2... Potential for strong to severe thunderstorms both Thursday and Friday afternoons, with greater coverage to the north.

The primary threat of severe weather today will remain to the north across Virginia, but a marginal (level 1 of 5) risk of severe thunderstorms currently extends one to two counties into North Carolina near the Virginia border. Diurnal cumulus has formed across the region, and MLCAPE values are between 1000 and 2000 J/kg. A lack of wind shear or a boundary will prevent much in the way of organized storms, but DCAPE values over 1000 J/kg will bring the potential for strong wind gusts in any storms that do develop. Overall coverage of thunderstorms should remain isolated.

As for Friday, the MCS currently producing severe weather across the Plains will move southeast over the next 24-36 hours, serving as the focus for organized thunderstorms Friday afternoon. The Thursday afternoon update to the Friday severe potential slightly expanded both the slight risk and marginal risk for severe weather an additional 1-2 counties farther south. The current timing for the MCS does not bring it into the Triad until at least mid-afternoon, which not only means that the severe potential would be more in the late afternoon and evening hours, it would also allow for a longer period of heating during the day. MLCAPE values will be between 1000 and 2000 J/kg, and while shear values won't be much higher Friday than they are today, the existing MCS will be able to help organize storm development. Nearly all precipitation should come to an end by midnight. Friday's primary severe weather threat will be damaging wind. Finally, in addition to the severe weather threat, there is a marginal threat for excessive rainfall tomorrow. Despite the drought conditions, if rain rates are heavy enough for a long amount of time, there will still be the potential for flooding.

KEY MESSAGE 3... Afternoon and evening thunderstorm chances will continue each day Saturday into the middle of next week.

A weakening cold front will move across much of our region late Friday night and Saturday, stalling over southeastern NC over the weekend. The next cold front will approach on Sunday and move into the area on Monday, where it may linger into mid-week. Diurnal, pulse-type convection is expected daily into next week. For now, the days with the highest probability of showers/storms appears to be Sunday and Tuesday. Rainfall amounts remain a bit uncertain at this time.

AVIATION /00Z FRIDAY THROUGH TUESDAY/

As of 740 PM Thursday...

Storms that developed earlier between RDU and RWI have largely dissipated. However, lingering pop-up storms continue to develop along lingering outflow boundaries, primarily northwest of FAY and northwest of RWI. There is the potential for some storms again at RWI between 00z-02z but confidence was not high enough to include. We did include a period of VCTS at FAY until 02z given storms northwest of the terminal. Otherwise, conditions should trend quiet tonight as the atmosphere stabilizes. No threat of fog is anticipated but cannot be ruled out near RWI where rain fell. A good chance of showers and storms will exist Fri afternoon and evening with the approach of a convective system and frontal boundary. The northern terminals have the highest chance thus far, but opted for PROB30 groups to start given large spread in the CAM high-res guidance.

Outlook: Diurnally driven showers/storms are expected each day this weekend, with greater coverage on Sunday and Tuesday. Local restrictions will be possible at any terminal with the precipitation, as well as later that night around sunrise.

CLIMATE

Record High Temperatures:

June 11: KGSO: 98/1914 KRDU: 100/1914 KFAY: 102/1926

June 12: KRDU: 98/2002 KFAY: 99/1926

June 13: KRDU: 100/2002 KFAY: 99/2022

June 14: KGSO: 98/1926 KRDU: 97/1944 KFAY: 100/2022

Record High Minimum Temperatures:

June 11: KGSO: 74/2008 KRDU: 74/2008 KFAY: 77/1981

June 12: KGSO: 72/1998 KRDU: 75/1986 KFAY: 76/2016

June 13: KGSO: 73/2015 KRDU: 75/2025 KFAY: 77/1998

June 14: KGSO: 71/2025 KRDU: 79/2022 KFAY: 77/2022

June 15: KGSO: 74/2022 KRDU: 78/2025 KFAY: 76/1926

June 16: KRDU: 75/2025 KFAY: 77/2015

RAH WATCHES/WARNINGS/ADVISORIES

Heat Advisory from 11 AM to 8 PM EDT Friday for NCZ007>011-021>028- 038>043-073>078-083>086-088-089.