textproduct: Raleigh

WHAT HAS CHANGED

* Greatest rain chances remain focused from this evening through Sun morning, although patchy rain may linger over the N and E through Sun afternoon.

* Sunday high temps continue to trend cooler, especially over the NE CWA behind the backdoor front.

* Shower/storm chances are increasing for Wed.

KEY MESSAGES

As of 255 AM Saturday...

1) Much above normal temps persist today. Fairly low RH and ongoing dry fuels will lead to an Increased Fire Danger across south-central NC today.

2) High chances for measurable rain persist for later today through at least Sun morning. Expected amounts have increased a bit from yesterday, but this rain is unlikely to significantly improve our worsening drought.

3) Needed shower chances continue this upcoming week. Temperatures will be cool to start the week, then moderate followed by more cool weather late in the week.

DISCUSSION

As of 255 AM Saturday...

KEY MESSAGE 1... Much above normal temps persist today. Fairly low RH and ongoing dry fuels will lead to an Increased Fire Danger across south-central NC today.

Warm and deep high pressure will hold over the Southeast coast today, yielding low level thicknesses that remain around 25 m above normal. This will again favor highs in the mid 80s to near 90, although increasing afternoon clouds in the W CWA will lower insolation a bit there during the peak heating of the day. Despite this early season heat, our records should not be threatened (record highs today are 93 at RDU and 94 at FAY, both set in 1925). Heat Risk tied to these high temps remains a Level 2-of-4/Moderate today.

Due to the low level ridging spanning to our S, we'll continue to lack a tap of high low-level moisture into the area today, resulting in min dewpoints in the mid 40s to around 50 over much of the area. These values, along with the warm temps, will result in min RH values in the 25-35% range across the S, and in combination with very dry fine fuels and infrequent gusts up to 15-20 mph today will support an Increased Fire Danger over our southern sections today. A statewide burn ban remains in effect until further notice.

KEY MESSAGE 2... High chances for measurable rain persist for later today through at least Sun morning. Expected amounts have increased a bit from yesterday, but this rain is unlikely to significantly improve our worsening drought.

Our rain chances continue to focus on a now-weak but amplifying shortwave trough now over the Great Lakes into the Mid Miss Valley. This wave, accompanied by surface low pressure, will track ESE across the Appalachians and over the Northeast and Mid Atlantic today through tonight, gradually amplifying as it pushes slowly SE through NC then to our S and E through Sun. Low level moisture influx will remain limited with this wave through early Sun, with moisture largely confined to the mid levels, and while our chance for showers will ramp up later today and peak this evening and overnight, the modest low level moisture availability will somewhat limit precip amounts through this time frame. As the wave pushes gradually to our S and E Sun morning, the surface low will push off the Mid Atlantic coast and deepen, and the resulting strengthening NNE flow around the low will help push the backdoor front southward through our area Sun with the arrival of low cloudiness. While the initial round of showers and isolated storms is expected to push into our SE sections Sun morning, additional rain along the backdoor front could bring another uptick in pops through the day, mainly over N and E sections. Expected storm total rainfall amounts have gone up since yesterday but still sit at around a half to three- quarters of an inch, certainly welcome but not enough to significantly curtail our ongoing drought. Regarding thunder chances, forecast MUCAPE values are pretty meager, generally under 250 J/kg, albeit with decent deep layer bulk shear around 30 kts. Expect any storms to be scattered at most and disorganized, with a very low chance of strong storms.

The aforementioned deepening low off the coast and southward-pushing backdoor front will usher in cooler temperatures from the NNE Sun, as the cooler air mass wedges in from the NNE. Western and southern portions of central NC may see enough heating ahead of the front for highs in the mid to upper 70s, but with the earlier arrival of cooler air in the NE, highs from the Triangle region to the N and E are likely to be only in the mid-upper 60s, and the extreme NE CWA may see temps falling into the low 60s, with abundant post-frontal low cloudiness and gusty NE winds.

KEY MESSAGE 3... Needed shower chances continue this upcoming week. Temperatures will be cool to start the week, then moderate followed by more cool weather late in the week.

The next chance of showers after this weekend will likely come on Tuesday. However, it appears the model trends have been lower and lower on the chance of any meaningful rain Tuesday. There is another chance Wednesday and Wednesday night, followed by another chance Friday into next weekend.

Temperatures this week will start off cooler, with near normal readings in the lower 70s. Mid-week should feature a moderating trend back into the mid 70s to lower 80s by Wednesday. This should be followed by chilly high pressure that should build down into the region from the Upper Midwest late in the week. Much cooler air will be associated with this high pressure, and it could be even cooler if a system develops near the Gulf Coast and moves toward the Carolina coast late week.

AVIATION /12Z SATURDAY THROUGH WEDNESDAY/

As of 655 AM Saturday...

VFR conditions are expected to hold over central NC through at least this evening, although mid and high clouds will steadily increase from the west starting later this morning, as a front approaches our area from the NW. Skies will become bkn-ovc with bases lowering to 7- 9kft AGL, persisting through sunset, as sct showers move in from the W, reaching INT/GSO soon after 20z, RDU around 22z, and FAY/RWI after 00z, although vsbys should stay VFR through at least 06z. As a backdoor front drops N to S into NC late tonight, sub-VFR cigs will move in from the N, affecting RWI first, then RDU/FAY, with mainly MVFR cigs after 08z. Surface winds will be mostly from the SW or WSW under 10 kts, except around 10-12 kts with infrequent gusts to 15-18 kts 15z-22z.

Looking beyond 12z Sun, behind the backdoor front, sub-VFR cigs will dominate much of Sun and Sun night, with the lowest cigs at RWI and RDU, and patchy light rain is expected, especially at RDU/RWI. VFR conditions should return briefly for Mon, but another round of low cigs is possible Mon night into Tue. Rain chances and potential sub- VFR conditions will return Wed.

RAH WATCHES/WARNINGS/ADVISORIES

None.