textproduct: Raleigh

WHAT HAS CHANGED

As of 710 PM Tuesday...

* Added information about frost potential tonight.

KEY MESSAGES

As of 710 PM Tuesday...

1) Patchy to areas of frost are possible mainly in rural areas tonight.

2) Another cold front will bring mostly light rain, seasonably gusty winds, and roller coaster temperatures Friday into Saturday.

DISCUSSION

As of 710 PM Tuesday...

KEY MESSAGE 1... Patchy to areas of frost are possible mainly in rural areas tonight.

A cool air mass will continue to extend over the area through tonight, as a gradually modifying Canadian-source high centered near the Mid Atlantic coast pushes offshore. Current dewpoints are mostly in the upper teens to upper 20s, and while some recovery is likely this evening, the potential for good radiational cooling is fairly high, with only a veil of thin mid-high clouds passing over the area along with very light to calm winds beneath the surface ridge. Patchy to areas of frost are possible overnight mainly in rural areas of the Piedmont and N Coastal Plain, where the HREF shows a 60- 90% chance of lows tonight under 35F. While the true growing season has not yet begun in most of central NC, people are still advised to take necessary actions to protect sensitive plants and agriculture in these rural locations.

KEY MESSAGE 2... Another cold front will bring mostly light rain, seasonably gusty winds, and roller coaster temperatures Friday into Saturday.

Latest 12z guidance remains in good agreement of the synoptic pattern through mid-week with the only highlight coming from another strong cold frontal passage Fri through Fri night. Amidst mostly zonal flow over the CONUS, mean troughing over the Gulf of Alaska will continue to shed lobes of weak mid-level disturbances, some of which are expected to amplify as they progress into the Eastern CONUS by this weekend.

The next chance for measurable precipitation comes Fri into Fri night. Central NC will be displaced south of the better DPVA over the Mid-Atlantic and only experience meager H5 height falls. Primary forcing will come from a combination of low-level FGEN and weak perturbations rippling through a seasonably moist band of moisture along and behind the front. This should result in a medium-high probability of light stratiform rain behind the front, but low rainfall amounts (< 0.5"). Showers and some isolated storms can't be ruled out along and ahead of the front as mid-level lapse rates increase to > 7C/km from a remnant EML over the High Plains, but could also provide a cap and prevent any deep convection from developing as boundary layer moisture lacks Gulf moisture influence.

Surface conditions will likely become seasonably breezy ahead of the front (southwesterly wind gusts around 25 mph on Fri) and especially behind the frontal passage (northerly 25 to 35 mph on Sat). If these winds can overlap areas of low relative humidity, adverse fire behavior would be possible given the ongoing drought and dry conditions as well as lack of hardwood forest canopy.

AVIATION /00Z WEDNESDAY THROUGH SUNDAY/

As of 710 PM Tuesday...

VFR conditions are expected over the next 24 hrs at central NC terminals, with high confidence. Mid and high cloudiness will continue to pass over the area, most notably from this evening through daybreak, with mostly high thin clouds Wed. No vsby restrictions are expected. Light and variable winds likely tonight through much of Wed morning, then from the SSE or S at 5-10 kts the rest of Wed.

Looking beyond 00z Thu, VFR conditions are likely to hold into Fri, then an approaching cold front will bring a chance for sub-VFR conditions and light rain chances from late Fri into early Sat morning. VFR conditions should then return for late Sat through Sun.

CLIMATE

Record High Temperatures:

March 27: KGSO: 86/1921 KRDU: 87/2007 KFAY: 87/1946

Record High Minimum Temperatures:

March 27: KGSO: 60/2007 KFAY: 65/1949

RAH WATCHES/WARNINGS/ADVISORIES

None.