Marine Weather and Tide Forecast for Rustburg, VA

NEAR TERM /THROUGH SATURDAY/
AS OF 215 PM EDT Friday...

Key Messages:

1) Breezy conditions with cooler than normal temperatures continue into Saturday.

2) Dry weather is expected.

Troughing remains in place over the eastern United States as high pressure begins to build at the surface tonight. General flow will be from the northwest through Saturday, which will result in a continued cool airmass to remain locked in place.
Winds will also remain elevated through this evening, relaxing some overnight, but increase again through the day on Saturday.

Lows tonight will fall into the mid/low 40s, warming into the 60s and low 70s by tomorrow afternoon.

SHORT TERM /SATURDAY NIGHT THROUGH MONDAY NIGHT/
As of 1230 PM EDT Friday...

Key Messages:

1. Below normal temperatures through the period.
2. Showers expected for most locations Sunday through Monday night.

A look at the 23 May 00Z NCEP Ensemble Mean 500mb Geopotential Heights shows for Saturday night a closed low will be situated over the area of ME east to the Canadian Maritimes. A shortwave trough will be on the low's western flank, heading south toward the western Great Lakes and Upper Mississippi River Valley. A ridge will be over the northern Rockies, north into central Canada. A shortwave trough will moving trough the base of this ridge approaching the Four Corners region. Finally, a closed low will be situated south of the Gulf of Alaska. For Sunday/Sunday night, most of the features mentioned for Saturday night are expected to have made little bit of progress eastward. In the case of the low over the Gulf of Alaska, it is expected to amplify off the WA/OR coast. Additionally, the shortwave heading south is expected to reach the Great Lakes region.
For Monday/Monday night, not much change is expected synoptically.
However, a weak shortwave trough starts to develop over the Central Plains states.

At the surface, on Saturday night, low pressure will be over the Canadian Maritimes with an associated trough extending southwest, crossing parts of eastern VA/NC. High pressure will be over the Upper Mississippi River Valley. Low pressure will be over NM/TX with an associated trough/front extending east to the Gulf Coast states and tie in with the East Coast trough. For Sunday/Sunday night little change is expected in the overall surface pattern. For Monday/Monday night the Upper Mississippi Valley ridge builds southeast toward/into our region, and displaces the southern stream w-e front farther to our south.

A look at the 23 May 00Z NAEFS Ensemble Situational Awareness data shows 850mb temperatures will range from +6C to +9C, ne-sw, Saturday night. On Sunday, afternoon values will be in the +8C to +11C range, n-s. Sunday night value should be around +7C to +10C. For Monday, expect values in the +9C to +11C range, ne-sw. Monday night, values decrease a little to +8C to +10C, ne-sw.

The above weather patterns offer the following forecast. We are expecting temperatures to remain below normal for this time of year.
Our wind flow trajectories will continue to originate from the region of a stalled/slowing moving upper low pressure system over southeast Canada. Showers will start potentially late Saturday night in the far southwestern, and then spread across the area on Sunday. These showers will remain in the forecast through Monday night in various degrees of probability. The precipitation will be in response to the development of a warm front south of our region, with various shortwave troughs riding along the feature. By late Monday night, a stronger low pressure system along the front will head northeast into the Lower Ohio Valley, helping to direct a warm the warm front north towards our region. Surface high pressure to our north will nose south during time time period along the lee of the Appalachians, helping to establish a cold air damming scenario.
Rain falling into this feature will only help enhance of the strength of the low level inversion as another factor to have temperatures below normal.

Confidence in the above weather scenario is high.



LONG TERM /TUESDAY THROUGH THURSDAY/
As of 1230 PM EDT Friday...

Key Messages:

1. Showers possible each day.
2. Tuesday and Tuesday night could bring robust showers and storms, some with locally heavy rain.
3. Temperatures will trend from below normal to near normal.

A look a the 23 May 00Z NCEP Ensemble Mean 500mb Geopotential Heights shows a broad trough/low over the Great Lakes south into mid- Mississippi Valley Tuesday/Tuesday night. An upper ridge was over the Pacific NW and curved northeast into central Canada. A closed low was over the Gulf of Alaska. Another trough was off the CA coast.
For Wednesday/Wednesday night, little change is expected in the overall synoptic pattern. For Thursday/Thursday night, the Great Lakes trough amplifies and shifts east to near the spine of the Appalachians. On Friday, the east coast trough stalls and amplifies.

At the surface, for Tuesday/Tuesday night, high pressure will extend from the Upper Mississippi Valley eastward to off the coast of New England. Immediately south of this ridge axis, a persistent front will exist across portions of the Gulf Coast states, the Tennessee Valley, and the Southeast US. Along this same front, low pressure will be near the southern Appalachians. For Wednesday/Wednesday night, the w-e oriented ridge starts to get pinched off as low pressure from the south heads northeast into the mid-Atlantic region with a second trailing low over the Lower Ohio Valley. By Thursday/Thursday night, The center of high retrogrades and builds south along the Mississippi River Valley. An area of troughiness remains over the central Appalachians. On Friday, troughiness remains over the east coast, but shifted a bit farther east as compared to Thursday. The center of high pressure shifts farther south towards the Lower Mississippi River Valley.

A look at the 23 May 12Z NAEFS Ensemble Situational Awareness data shows 850mb temperatures around +9C to +12C, ne-sw on Tuesday.
Little change in the temperature range is expected Tuesday night, but the orientation changes to n-s. On Wednesday, values inch higher slightly to +11C to +12C, n-s. Wednesday night, values of +10C to +11C, nw-se are forecast. On Thursday through Friday, values around +11C or +12C will be common.

The above weather patterns offer the following forecast. Wet weather on Monday will trend even wetter for Tuesday as the warm front lifts north across the region, starting the process of eroding the lee side cold air damming. The warm front will be followed by a cold front Tuesday evening. With the region entering into the warm sector between the northward moving warm front, and eastward moving cold front, instability will increase across the area on Tuesday into Tuesday evening, especially western and southwestern sections.
Active and robust storms may be possible over this region. With these stronger showers and storms will come the potential for locally heavy rain as well during the Tuesday and Tuesday night time period for the entire area.

Wednesday into Thursday, and perhaps even Friday, we will continue within weather pattern conducive to additional showers, and perhaps thunderstorm. While high pressure will be building towards the area, its center will still be too far away to prohibit waves within the southwesterly flow aloft to cross the region. At the surface, anti- cyclone flow around the high will also allow weak disturbances within northwest flow to cross the area, allowing for a winter-like upslope flow pattern to bring showers to the mountains.

Temperatures will start the period below normal on Tuesday, but trend to values around normal by Friday.

Confidence in the above forecast scenario is low to moderate with the biggest question mark being timing of the weather post-Tuesday.

AVIATION /17Z FRIDAY THROUGH TUESDAY/
As of 125 PM EDT Friday...

VFR expected for the valid 24 hour TAF period. SCT to FEW clouds through this afternoon, clearing overnight. Gusty northwest winds will relax overnight for the lower elevations, but will remain elevated across the mountains.

Fewer clouds on Saturday. Winds will increase through late morning and could gust around 20kts from the northwest.

EXTENDED AVIATION OUTLOOK...

VFR conditions remain likely for most of the weekend, until the next system approaches Sunday afternoon, bringing a chance of showers across the area. Rain chances increase Sunday night into Monday, with likely sub-VFR conditions returning through midweek as widespread rainfall will impact all terminals each day.

RNK WATCHES/WARNINGS/ADVISORIES
VA...None.
NC...None.
WV...None.