Sunrise 6:01 AM   Sunset 8:24 PM Moonrise 4:48 PM   Moonset 3:16 AM

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FXUS61 KRNK 200605 AFDRNK

Area Forecast Discussion National Weather Service Blacksburg VA 205 AM EDT Mon May 20 2024

SYNOPSIS
High pressure will keep our area mostly dry through Wednesday.
Showers and a few thunderstorms return Thursday and linger into the weekend as a frontal boundary stalls over the area.
Temperatures will be near or a few degrees above normal for much of the week.

NEAR TERM /THROUGH TONIGHT/
As of 200 AM EDT Monday...

Key Messages:

1) Dry and warm, with clouds early.

An area of clouds was noted on satellite this morning, generally from Warm Springs and Lynchburg, then southwest towards Boone.
Just inland from VA Beach, an area of stratus was slowly making progress westward towards our southern Piedmont, but still looks a couple hours away. In between these areas of clouds, fog had developed. Drier air had allowed parts of the mountains to drop into the 50s so far this morning, with Burke's Garden in the 40s.

A trough of low pressure was oriented over the Mid Atlantic and into GA/Carolinas, with positively tilted high pressure from the Gulf Coast towards NY State. An area of negative vorticity will be steered over our area from the northeast today, on the eastern side of the ridge. This will help squash precipitation chances and decrease any lingering cloud cover after mid morning. PWATs remain below an inch, and this combined with highs in the 70s to low 80s and sunshine will make for a pleasant day. The only chance for an isolated shower would be over the far southern Blue Ridge this afternoon.

Tonight, winds become light and variable as high pressure retreats east. Expect another shot of stratus migrating from the coast Monday morning, possibly reaching the southern Piedmont.

Confidence in the near term is high.

SHORT TERM /TUESDAY THROUGH THURSDAY NIGHT/
As of 1245 AM EDT Monday...

Key Points:

1. Well above normal temperatures.
2. Mainly dry Tuesday through Wednesday.
3. Showers and storms increase west to east across the region on Thursday.

A look at the 19 May 00Z NCEP Ensemble Mean 500 mb Geopotential heights shows the region will be within a pattern of general sw- ne flow with a shortwave trough passing north of the area on Thursday into Thursday night. Concurrently, a ridge of high pressure will build over the SE US. At the surface, on Tuesday, low pressure is expected to be centered over the Upper Mississippi River Valley, with high pressure centered just off the mid-Atlantic coast. By Wednesday, the center of the high is displaced eastward by the advance of the low to near the Ontario/Quebec border. An associated cold front is expected to extend southwest into Lower Ohio/Mid Mississippi Valley. By Thursday, the low is over western Quebec with the associated cold front over or just east of our area by Thursday evening.

Output from the 19 May 12Z Ensemble Situational Awareness Table shows 850mb temperatures climbing slowly Tuesday through Wednesday night. Values will average +16C across the area by Wednesday, which is within the range of the 90 to 97.5 percentile of the 30-year climatology for much of the area, and the 97.5 to 99 percentile for portions of the area near the WV/VA border. On Thursday, values dip a degree or two during the day, and by late Thursday night range from roughly +12C to +14C across the area. Precipitable Water values on Tuesday will average 0.75 to 1.00 inch across the area on Tuesday. These values will be on the increase through Thursday, averaging around 1.25 inches by the mid-afternoon on Thursday. This values just touches the low end of the 90 to 97.5 percentile of the 30-year climatology for this time of year. By late Thursday night, values will range from 0.75 to 1.25 inches across the area, with the high end of this range across the southeast portion of the region.

The above pattern suggests a period of well above normal temperatures with limited, if any, precipitation chances Tuesday and Wednesday. However, as the cold front approaches, and then crosses our area on Thursday, first look for the arrival of scattered showers over southeast West Virginia late Wednesday night. During the day Thursday, look for showers and storms to increasing in coverage from west to east as the day progresses, with the best chances of storms during the afternoon and evening hours. Coverage will slowly decrease through the night.

Confidence in the above weather scenario is moderate to high.

LONG TERM /FRIDAY THROUGH SUNDAY/
As of 1245 AM EDT Monday...

Key Points:

1. Above normal temperatures.
2. Daily chances of mainly mid-afternoon through early evening showers and storms.

A look at the 19 May 00Z NCEP Ensemble Mean 500 mb Geopotential heights shows the region remaining a general sw-ne flow aloft, but will gradually increasing heights each day. The latitude of passing shortwave troughs on the north side of the prevailing flow are expected to trend farther north. One such feature is expected to cross north of the region Saturday into Sunday. At the surface, for Friday through Sunday, the pattern transitions into one with a persistent low/trough over central CONUS and high pressure/ridge over over the Atlantic Ocean. This places our region within a generally southerly flow pattern with trajectory origins from either off the eastern Gulf of Mexico or coasts of SC/GA.

Output from the 19 May 12Z Ensemble Situational Awareness Table shows 850mb temperatures averaging around +14C across the area Friday and Saturday, and inch closer to a +16C average by Sunday. Precipitable Water values during this portion of the forecast will average 1.00 to 1.25 inches.

The above pattern suggest our region Friday through the weekend will be within a very mild and humid airmass. This pattern may allow for daily chance of showers and storms. First on Friday, the front that crossed the area on Thursday, may pivot north thanks to increasing southerly flow, and be the focus for showers and storms. Saturday into Sunday, we will remain in a potentially unstable airmass with residual outflow boundaries from the previous day's convective activity being potential initiation locations for that day's convective activity.

Confidence in the above weather scenario is moderate to high regarding the general synoptic pattern and above normal temperatures. However, confidence is low regarding the specific locations of the forecast area that will have the greatest chances of showers and storms each day, and the specific timing of that activity. Although, mid-afternoon through early evening would be the most likely range of times.

AVIATION /05Z MONDAY THROUGH FRIDAY/
As of 200 AM EDT Monday...

Areas of IFR/LIFR/MVFR fog and stratus will continue to develop this morning before improving to VFR after 13-14Z. Some VFR afternoon cloudiness possible this afternoon, especially over the ridges. Late tonight into Tuesday morning, fog may be a little harder to come by. An area of stratus, again making its way from coastal VA similar to this morning, may impact LYH and DAN.

Otherwise VFR Tuesday.

EXTENDED AVIATION OUTLOOK...

VFR conditions persist into Wednesday, and possibly for parts of the area the first half of Thursday. However, chances for SHRA/TSRA increase beginning Thursday and continuing into the weekend, as a front stalls across the area. This will bring increasing periods of IFR/LIFR/MVFR conditions.

Winds will become more southerly Tuesday, then become more west/SW Wednesday through Friday.

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

Falling Creek entrance
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Mon -- 02:36 AM EDT     3.72 feet High Tide
Mon -- 04:09 AM EDT     Moonset
Mon -- 05:56 AM EDT     Sunrise
Mon -- 09:43 AM EDT     0.63 feet Low Tide
Mon -- 03:03 PM EDT     3.19 feet High Tide
Mon -- 05:41 PM EDT     Moonrise
Mon -- 08:16 PM EDT     Sunset
Mon -- 09:27 PM EDT     0.63 feet Low Tide
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Falling Creek entrance, James River, Virginia, Tide feet

Petersburg
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Mon -- 02:32 AM EDT     3.37 feet High Tide
Mon -- 04:08 AM EDT     Moonset
Mon -- 05:56 AM EDT     Sunrise
Mon -- 09:51 AM EDT     0.57 feet Low Tide
Mon -- 02:59 PM EDT     2.89 feet High Tide
Mon -- 05:40 PM EDT     Moonrise
Mon -- 08:15 PM EDT     Sunset
Mon -- 09:35 PM EDT     0.57 feet Low Tide
Tide / Current data from XTide NOT FOR NAVIGATION

Petersburg, Appomattox River, James River, Virginia, Tide feet

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