textproduct: Raleigh

WHAT HAS CHANGED

* No major changes with the early morning forecast update.

KEY MESSAGES

As of 115 AM Tuesday...

1) Potential for hazardous heat appears likely on Thursday for the Coastal Plain and Sandhills.

2) The best chance of showers and thunderstorms appears to be late Thursday into Friday night (centered on Friday). However, the window of time for much needed rainfall appears limited to late Thursday into Friday.

DISCUSSION

As of 115 AM Tuesday...

KEY MESSAGE 1... Potential for hazardous heat appears likely on Thursday for the Coastal Plain and Sandhills.

A significant area of low pressure (sub 990 at times) traversing the Great Lakes will advect anomalously warm 850mb temps over the Mid-Atlantic and Carolinas from the central Plains by Thurs. This would bring back the risk for hazardous heat on Thurs. A potential failure mode will be the chance for upstream convection to shift into the region from the Ohio Valley. This leads to a low confidence temperature forecast across the Piedmont. Although confidence is increasing that the Coastal Plain and Sandhills will remain dry through the daytime hours.

Thurs will feature the best chance for hazardous heat to develop when 20-22C 850mb temperatures spread across the area, and would support 2m temperatures of upper 90s to around 100, given sufficient insolation and limited convection/outflow. HeatRisk highlights widespread Major category is likely for the eastern Piedmont, Sandhills and Coastal Plain, indicating that not only is this heat particularly unusual, it is correlated with high levels of heat illnesses as noted by historical CDC heat-health data, and this heat could produce health impacts on all populations, especially those without adequate hydration and cooling.

KEY MESSAGE 2... The best chance of showers and thunderstorms appears to be late Thursday into Friday night (centered on Friday). However, the window of time for much needed rainfall appears limited to late Thursday into Friday.

Unfortunately the way it appears at the moment, the potential Gulf Coast system may very well track too far to our south to give us much needed rainfall. This will be watched.

However, as of the current models. They indicate a strong "kicker" upstream in the form of a strong short wave that will arrive with the next northern stream trough Friday. Thus, the gulf moisture would have only a small window of time to arrive in our region. In fact, we may have to rely on the short wave trough and its moisture and lift for even scattered thunderstorms as it appears now. In addition, as the trough moves through late week, it will shut off any deep moisture influx over central NC and force it east and south of the region. This would bring rapid drying again behind another cold front late Friday, with dry weather for next weekend.

So, as of this moment the best chance of showers/storms will likely be with the approaching trough from the Midwest and TN valley late week. If the gulf coast system does develop more than currently anticipated, it could potentially bring needed rain. Otherwise, the window of opportunity will be slammed shut again by another northern stream trough, with only scattered storms late Thursday into Friday. Obviously not what the drought ravaged areas need. Even if it is stronger than anticipated, the "kicker" from the Midwest may very well keep the system well to our south.

Even though we are advertising relatively high POP Thursday night and Friday - the QPF is currently low. And, these POPs are likely overdone as they have been lately by the models.

No rain at most locations in the past 15-20 days. Maybe the models will catch on eventually?

AVIATION /06Z TUESDAY THROUGH SATURDAY/

As of 115 AM Tuesday...

High confidence remains in prevailing VFR conditions through the TAF period as BKN/OVC mid/high clouds spread across the area. SCT/BKN 5-7 kft is likely through this morning as moisture pools underneath an inversion aloft. We will be watching an area of MVFR cigs along coastal NC that may advect westward within the easterly surface flow in the Coastal Plain. As of now, confidence and lack of model support precludes the inclusion in the 06z TAFs for RWI at this time. North to northeasterly flow will back to south to southwesterly by this afternoon.

Outlook: Moisture return may bring an isolated shower and brief sub- VFR conditions late Tue night into Wed morning, most favored at FAY. Latest probability of IFR cigs at FAY is around 40% between 09 and 12z. Breezy southwesterly winds of around 15 kts and gusting to 25-35 kts are expected Thu into Fri, maximized with daytime heating. A late-week cold front and surface wave will favor a return of showers/storms and sub-VFR conditions in the Thu/Fri time frame, although confidence remains low on timing and location.

CLIMATE

Record High Temperatures:

June 18: KGSO: 100/1944 KRDU: 98/2015 KFAY: 102/1944

Record High Minimum Temperatures:

June 18: KGSO: 73/2018 KRDU: 77/2025 KFAY: 76/2017

June 19: KGSO: 77/1970 KRDU: 73/2025 KFAY: 77/2017

RAH WATCHES/WARNINGS/ADVISORIES

None.