textproduct: Raleigh

SYNOPSIS

Low pressure over southeastern Virginia will move off the Mid- Atlantic coast tonight. High pressure will extend over the area through late week.

NEAR TERM /THROUGH TONIGHT/

As of 132 PM Wednesday...

* Patchy fog development possible tonight

Surface analysis and satellite imagery reveal the slow-moving area of low pressure is still rotating counterclockwise over southeastern VA. A large area of stratus remains around the system, with the western edge of the low clouds from Alamance to southern Wake to southern Wayne Counties. As a result, a quite variable range in temperatures are present, with low to mid 60s in the NE, to as warm as the low 80s near Wadesboro. Highs should top out in the low 80s in the W and SW to upper 60s in the far NE. Radar continues to show some lingering light rain or drizzle across the northeast Piedmont and northern Coastal Plain with the wrap around moisture. These light rain or sprinkles can be expected off and on over the next few hours in the NE before the low departs off the VA coast.

Tonight, the aforementioned low should exit of the Mid-Atlantic coast, leading to gradual clearing of the low cloud deck. Lingering low-level moisture and some patchy mist should then favor the development of patchy fog, primarily for areas along and north of US- 64 of the Piedmont and Coastal Plain. Areas that saw rain as well this morning over the northern Piedmont may be more susceptible to fog development overnight to early Thu morning. Lows should drop into the upper 50s to low 60s.

SHORT TERM /THURSDAY AND THURSDAY NIGHT/

As of 132 PM Wednesday...

* Warmer with 80s area-wide

Weak high pressure will be centered over the region in the wake of the departing low, beneath broad troughing at mid-levels over northern GA/SC. The airmass warms significantly from Wed, with conditions typical for late June. Highs should return above normal area-wide with low 80s NE to upper 80s SW. Clear skies and light winds Thu night should favor lows in the upper 50s to low/mid 60s.

LONG TERM /FRIDAY THROUGH WEDNESDAY/

As of 345 PM Wednesday...

Ridging aloft over the Eastern US will result in mostly sunny skies and warm temperatures on Friday with highs in the mid-80s to 90. This is 5-10 degrees above normal. However, dew points won't be oppressive and will mix out into the mid-50s to lower-60s in the afternoon. While no POPs are currently in the forecast, latest model guidance is trending toward the possibility of some isolated convection due to the daytime heating and modest levels of moisture and instability, so the forecast may change in future updates. Lows Friday night will be in the upper-50s to mid-60s, which is also above normal.

On Saturday, surface high pressure will move SE from southern Quebec into northern New England. A cool air wedge associated with this high will drop a backdoor cold front through central NC which stalls to our south. The front may also be associated with isolated showers (mainly north and west), but any convection would be limited by the high pressure wedging and a lack of upper forcing. E/NE winds will be a bit breezy on Saturday and especially Sunday. While Saturday still looks warm with highs in the mid-to-upper-80s, it will turn slightly cooler behind the front on Sunday with highs in the upper- 70s to mid-80s. Forecast lows this weekend are in the lower-to-mid- 60s.

The cool air wedging will gradually move to our west and erode early next week as the surface high pressure system over New England moves east into the Atlantic. This will result in a slow warming trend. After Monday has similar highs to Sunday (upper-70s to mid-80s), temperatures will increase to lower-80s to upper-80s by Wednesday. Meanwhile a mid/upper trough moving into the Pacific NW on Sunday will become a cutoff low that is nearly stationary somewhere over the Plains from early to mid next week. While any small shower/storm chances look confined to the SE near the stalled front on Sunday and Monday, the cutoff low and increasing PW values may bring a better chance areawide on Tuesday and Wednesday. However, most guidance at this time keeps any significant precipitation to our west. The wet deterministic 12z GFS is an outlier even compared to its own ensembles, and the ECMWF is largely dry. Still, model differences and this being days 7-8 mean there is time for things to change.

AVIATION /00Z THURSDAY THROUGH MONDAY/

As of 734 PM Wednesday...

00Z update: Little changes to the forecast this evening. KRWI may bounce around from MVFR to VFR for the next several hours before going VFR till later tonight. Still think the best chances for fog/stratus and associated flight restrictions are at KRWI/KRDU and perhaps at KGSO. Otherwise the 18Z discussion and rationale below remains valid given latest observations and model trends:

A mixture of VFR and MVFR conditions will start the TAF period. An area of low pressure over southeastern VA is continuing to promote lingering MVFR ceilings at RWI and partially at RDU. This area of low pressure will gradually shift off the Mid-Atlantic coast tonight. This should favor MVFR ceilings gradually improving at RWI by early this evening, though cannot rule out that these MVFR ceilings linger longer than expected in the latest forecast. Otherwise, VFR should largely take over until later tonight. Lingering low-level moisture in the wake of the departing low combined with winds becoming calm will favor areas of low stratus and possible fog Thu morning. As of now, the best chance of fog appears at RDU, GSO, and possibly RWI. Confidence was not high enough to show prevailing fog at any terminal, however. Fog would be more favored at RWI if the low ceilings can clear out. Conditions should return to VFR at all terminals by mid-morning Thu, though may linger a tad longer than currently expected at RWI. West to northwest winds today will become light tonight and Thu.

Outlook: Largely VFR conditions are expected through Monday.

RAH WATCHES/WARNINGS/ADVISORIES

None.