textproduct: Raleigh

SYNOPSIS

Arctic high pressure will weaken and modify over the Carolinas through Wednesday. A warm front will lift north across the region on Thursday. A cold front will sweep across the area late Thursday and Friday.

NEAR TERM /THROUGH TONIGHT/

As of 1220 PM Tuesday...

A warming trend is occurring today as high pressure continues to move off the coast to our south. This will cause light southerly to southwesterly surface winds over the region, allowing highs to rise generally into the upper 40s to around 50. This should still be about 5-10 degrees below normal for this time of year. Tonight, temperatures look to drop below freezing everywhere in central NC, with the coldest areas reaching mostly the upper 20s to around 30, with some cooler locations reaching the mid 20s.

SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/

As of 115 PM Tuesday...

Overview: Aloft, as a nrn stream s/w passes to the north on Wed, a second s/w will approach from the west. This second s/w will progress ewd across the area Wed night. Meanwhile to the west, the longwave trough will amplify over the Plains/MS Valley as a potent nrn stream s/w moves across the Rockies and into the Plains Wed/Wed night. The srn stream s/w over the NW Gulf will lift quickly newd into the Southeast US on Thu as the nrn stream s/w moves ewd across the Plains and MS Valley. Both shortwaves will continue ewd across the Southeast US and mid-Atlantic Thu night, with the longwave trough moving into the region on their heels. At the surface, Bermuda high will remain in place, ridging into the Southeast US during the day Wed, while a lee trough weakens and a transient high moves across the nrn mid-Atlantic. As the high shifts offshore and strengthens Wed night, a warm front will begin lifting nwd into the area. While some weak ridging may extend across the far nrn/nwrn portions of central NC Thu morning, largely expect the warm front to lift across most of the area by mid-day. The question is whether some in-situ CAD is able to set up and how long it remains in place on Thu. With the warm advection and isentropic lift, the low-mid levels should quickly saturate Thu morning, with some light rain possible in the west, though confidence on occurrence is not high. In the wake of the warm front, sly flow will increase, the pressure gradient also increasing as a strong cold front approaches from the west. The cold front should cross the Appalachians Thu night, but guidance varies wrt how far east it progresses by 12Z Fri. Latest consensus suggests it may be moving into or through the Triad by Fri morning.

Precipitation: Wed/Wed night should largely be dry. Some light rain is possible in the west Thu morning, but otherwise the chances for rain and showers are maximized Thu night, roughly between 00Z and 12Z Fri, coincident with the s/w passages aloft. Rainfall totals generally one-half to three-quarters of an inch across central NC. Some thunder will be possible, with the highest chances across the Sandhills and srn/cntl Coastal Plain.

Temperatures: Highs Wed generally in the mid to upper 50s, with lows Wed night ranging from low/mid 30s north to around 40 degrees south. Thu will be tricky, as it depends on the potential in-situ CAD development and progression of the warm front. For now, expect highs ranging from around 50 degrees NW to mid 60s SE, with the potential to be off by a few/several degrees

LONG TERM /FRIDAY THROUGH TUESDAY/

As of 1200 PM Tuesday...

* Strong wind gusts of 20 to 35 mph will be possible on Friday.

* A dry reinforcing cold front on Sun and strong high pressure building into the region will likely keep rain chances limited into early next week.

The leading edge of a cold front will be pushing through the area through Fri morning. Cloud coverage should effectively clear out through the morning into the early afternoon hours as the mid/upper level pivots across the Mid-Atlantic and a drier Canadian airmass filters into the region. Wind gusts 15 to 25 mph will be common through the morning hours behind the fropa, but as cloud coverage clears, frequent wind gusts of 20 to 30 mph should be expected and infrequent gusts of around 35 mph will also become possible. Wind gusts should cease around sunset as the pressure gradient begins to relax and the surface decouples with nocturnal cooling.

As far as precipitation chances, the forecast turns quieter through early next week. A warm front will develop over the Mid-Mississippi Valley Sat and shift into the Southeast on Sun ahead of an approaching cold front motoring through the Ohio Valley. Moisture return north of the warm front appears limited/short-lived and provide little moisture to subsequently be lifted by the cold fropa on Sun; this will keep the forecast mostly dry. Strong +1030mb surface high pressure will settle over the Mid-Atlantic by Mon. An elevated warm-frontal zone will likely spread mid/high clouds back into the area Mon evening into Tues, but precipitation appears limited.

AVIATION /00Z WEDNESDAY THROUGH SUNDAY/

As of 847 PM Tuesday...

VFR conditions with vrb to light sfc flow will prevail through mid Wednesday morning. Before the inversion breaks, a low-level jet will strengthen primarily over the Coastal Plain/central Piedmont. As such, there could be a period of marginal LLWS at KRDU/KFAY/KRWI, but confidence is too low to include in the TAFs at this juncture. Otherwise, when the inversion lifts, expect sswly gusts of up to 20 kts at KFAY/KRWI Wednesday afternoon before diminishing at sunset. Otherwise, expect high level clouds to move in over the area and persist through the end of the TAF period.

Outlook: VFR conditions will prevail through Wednesday. Flight restrictions and rain will accompany a frontal system across the region Thu-Thu night. Additionally, low-level wind shear will be possible Wed morning. VFR and dry weather will return on Friday and Saturday.

RAH WATCHES/WARNINGS/ADVISORIES

None.