textproduct: Raleigh

WHAT HAS CHANGED

* Temperatures will probably not be as hot as forecast Fri onward, especially with onshore flow next Mon-Tue

KEY MESSAGES

As of 255 AM Wednesday...

1) Becoming hotter Fri-Sun, trending less so next Mon-Tue, then possibly dangerously so mid to late next week

2) Diurnally-maximized chances for convection this weekend will probably peak Sun, with the passage of a backdoor cold front and amid nwly flow and with possible upstream convection/MCS influence, followed by mainly dry conditions most of next week.

DISCUSSION

As of 255 AM Wednesday...

KEY MESSAGE 1... Becoming hotter Fri-Sun, trending less so next Mon- Tue, then possibly dangerously so mid to late next week

A couple of sub-tropical highs initially over nrn MX and the wrn N. Atlantic will merge and amplify across the mid-South and MS Valley Sun-Mon, downstream of a vigorous cyclone forecast to progress from the Gulf of AK to the Great Basin. The associated strong mid-level high and surrounding ridge will then expand ewd and into the OH and TN Valleys by the middle of next week.

At the surface, 1021 mb high pressure and associated continental air now building from the Great Lakes to the Middle Atlantic will have drifted offshore by the end of the week and become absorbed by a stronger high over the lower mid-latitude and sub-tropical cntl N. Atlantic. Increasingly-hot, swly flow will be directed across the Carolinas and into both an Appalachian-lee trough and a wavy frontal zone forecast to extend from the mid MS Valley to the srn Middle Atlantic. Cntl NC will be situated to the south of that frontal zone until Sun, when it will likely settle swd and across NC. Following high pressure will build across and offshore the Middle Atlantic early next week, with associated ely/onshore flow directed into the Middle and South Atlantic coast, and which should curb the heat over cntl NC Mon-Tue. The intensifying heat across the interior Atlantic states, and especially over the OH and TN Valleys during that time, will then probably expand east of the Appalachians and into cntl NC mid to late next week, when dangerously hot conditions will become more likely.

KEY MESSAGE 2... Diurnally-maximized chances for convection this weekend will probably peak Sun, with the passage of a backdoor cold front and amid nwly flow with possible upstream convection/MCS influence, followed by mainly dry conditions most of next week.

Generally climo (slight) probabilities of convection on Sat will focus where surface convergence will maximize along the Piedmont trough, sea breeze, and possibly outflow settling swd from frontal convection over the Virginias. A better chance of convection (~30- 50%) will exist on Sun, with the passage of the aforementioned backdoor cold front and amid nwly flow and with possible upstream convection/MCS influence. The most intense storms will be capable of producing damaging downbursts given what will be a hot and deeply mixed BL with steep low-level lapse rates and large dewpoint depressions around 30C. Anticyclonic, onshore flow will then limit precipitation chances Mon-Tue.

AVIATION /12Z WEDNESDAY THROUGH SUNDAY/

As of 641 AM Wednesday...

Through 12Z Thu: VFR and light winds (less than 10kt) expected through the TAF period thanks in large part to high pressure over our area.

Outlook: VFR conditions are expected through Thu. A return to isolated or scattered diurnal convection is favored Fri-Sun with another frontal system, as well as the potential for early morning stratus late in the week and upcoming weekend

CLIMATE

Relevant Record High Minimum Temperatures:

June 27: KGSO: 76/1969 KRDU: 76/1952 KFAY: 77/1998

June 28: KGSO: 76/1969 KRDU: 76/1952 KFAY: 78/1914

June 29: KGSO: 74/2024 KFAY: 76/1969

RAH WATCHES/WARNINGS/ADVISORIES

None.