Sunrise 6:06 AM   Sunset 8:17 PM Moonrise 1:54 PM   Moonset 2:09 AM

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FXUS62 KRAH 172335 AFDRAH

Area Forecast Discussion National Weather Service Raleigh NC 735 PM EDT Fri May 17 2024

SYNOPSIS
The region will remain in a warm, humid, and unsettled weather pattern through early Sunday. Cool high pressure will build in from the north Sunday through Monday, then shift off the Mid Atlantic coast late Monday.

NEAR TERM /THROUGH TONIGHT/
As of 300 PM Friday...

A shortwave over OK/TX will move east to the lower MS Valley through tonight, as mid/upper ridging remains just off the Southeast US coast, with central NC under the influence of WSW flow aloft in between these two features. The latest surface analysis shows a weak boundary/convergence axis stretching from the NE Piedmont into the central Coastal Plain, accompanied by a wind shift from E/NE to S.
Meanwhile a quasi-stationary frontal zone extends across the northern Gulf Coast, which is being overtaken by an MCS across southern MS/AL/GA. This MCS will continue to move east and off the coast by this evening, weakening as it does so. Weak perturbations in the WSW flow aloft will help generate scattered showers and maybe a few storms this afternoon and evening. A few showers with limited lightning have already begun to develop in the Coastal Plain along the convergence axis, and more showers are observed across western NC and eastern TN. The MCS to our south seems to be choking off some of our moisture feed, though we are still in a soupy airmass with dew points in the mid-to-upper-60s and PW values around 1.5 inches.
Today's mid-level lapse rates are very unimpressive as temperatures aloft are fairly warm. There are also widespread mid and high clouds across the area which will continue through the afternoon. These factors will limit instability, as current SPC analysis shows MLCAPE around 500 J/kg and it is only expected to reach 500-1000 J/kg at most. Thus not expecting storms today to be widespread, and not concerned about anything severe. POPs are mostly slight to chance today, highest across the north and west. As another perturbation aloft approaches and the MCS to our south moves away, shower coverage may actually increase in the evening and overnight hours, still highest in the north and west where POPs are likely. However, with the nocturnal timing any instability looks limited and elevated, and only carry a slight chance of thunder overnight. High temperatures today will be in the mid-70s to lower-80s. Lows tonight will be mild (in the 60s) with the overcast skies and precipitation.

SHORT TERM /SATURDAY THROUGH SATURDAY NIGHT/
As of 240 PM Friday...

Overall showers and thunderstorms are expected in all locations tomorrow, although confidence is low in overall potential for severe weather. Showers/storms should be ongoing across the northeast around sunrise, then there should be a relative lull across the area during the morning hours. By the afternoon, coverage of storms should increase from north to south, with greatest coverage likely to occur during the late afternoon. Showers will continue through the evening, with rain possibilities dropping to chance after midnight.

Confidence is low in where severe weather could occur because of the uncertainty of today's upstream MCSs moving into the region and how those boundaries will affect development of storms tomorrow along with moisture transport from the south. However, instability has the potential to range between 1000 and 2000 J/kg along with 30-40 kt effective bulk shear. The afternoon Day 2 update from SPC had minimal changes in the convective risk from the overnight issuance, with half a dozen southern counties still under a slight (level 2 of 5) risk and the rest of the forecast area under a marginal (level 1 of 5) risk. Damaging winds will be the primary threat for severe weather, with large hail the secondary threat. In addition, the entire forecast area is under a marginal (level 1 of 4) risk for excessive rainfall.

Temperatures appear to be cool near the VA/NC border with highs in the lower 70s with the rest of the area in the upper 70s and lower 80s. Overnight lows should range from the mid 50s to the lower 60s.

LONG TERM /SUNDAY THROUGH FRIDAY/
As of 255 PM Friday...

Sunday and Monday: Aloft, the mid/upper s/w will be over the mid- Atlantic and Carolinas early Sun, drifting slowly sewd through the area through Sun night. By Mon morning, the trough should be offshore, with the sub-tropical ridge building from the southern plains to the Northeast US. Both the trough and the ridge will shift slightly ewd through Mon night, with the ridge over the Appalachians by 12Z Tue. At the surface, the surface low will be off the Carolina coast, with a backdoor cold front through the area and cool high pressure ridging into the area by early Sun. The ridge will strengthen over the area Sun and generally remain in place through Mon night, while the low sits/drifts slowly eastward offshore. There is some continued forecast uncertainty, especially wrt temperatures Sun and Mon. The model solutions have trended drier for Sun and Mon, with Sun still potentially wet. However, chances for storms will be limited to the far south or southeast. While Mon should be largely dry, there is still the possibility for a brief period of lingering light early.

Temperatures: Tricky, especially Sun as there is some bust potential with the wedge airmass and possible light rain, but for now expect highs ranging from mid/upper 60s NE to low/mid 70s SW. Lows Sun night generally in the low to mid 50s. For Mon, some continued uncertainty in highs, but for now expect low/mid 70s east to mid/upper 70s west. Lows again in the low to mid 50s.

Tuesday onward: The ridge axis will generally remain over the area through at least Wed night. The ridge will be suppressed sewd Thu/Fri as a s/w tracks from the mid-MS Valley, enewd into the northern mid-Atlantic/Northeast US. This wave may amplify the larger scale trough over the Northeast and mid-Atlantic Thu night/Fri. The next potential for showers/storms across the area will be with this disturbance Thu/Thu night. Expect temperatures to moderate through mid-week.

AVIATION /00Z SATURDAY THROUGH WEDNESDAY/
As of 735 PM Friday...

A few rounds of showers and isolated storms will track toward the NNE over central NC terminals tonight, bringing periods of MVFR to IFR cigs, with overcast skies. While a shower can't be ruled out at any given location during this time, the focus for potential thunder and the greater chance of rain will be 03z-08z. IFR cigs and MVFR to IFR vsbys are expected to spread across the area tonight, mainly after 06z, with high confidence that IFR conditions will persist at all central NC terminals from through at least 15z (and perhaps lasting until 18z at RWI). Cigs will lift to MVFR by 15z-19z then to VFR for the rest of the day, although the chance of thunderstorms will increase starting around 20z Sat. Some of these storms could be quite strong. Outside of any storms, surface winds will be light and variable, but becoming from the S and SW after 15z at 5-10 kts.

Looking beyond 00z Sun, we'll stay in an active weather pattern with periods of wet weather and sporadic sub-VFR conditions likely through early Sun, as a slow-moving upper level trough drifts over the region. The greatest chance for sub-VFR cigs/vsbys will be late Sat night, which are likely to last through Sun morning, although mostly dry weather is expected midday Sun through Mon morning. VFR conditions should return for midday Mon through Wed. -GIH

RAH WATCHES/WARNINGS/ADVISORIES
None.

Bannermans Branch
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Fri -- 03:04 AM EDT     Moonset
Fri -- 06:06 AM EDT     0.15 feet Low Tide
Fri -- 06:06 AM EDT     Sunrise
Fri -- 11:54 AM EDT     1.24 feet High Tide
Fri -- 02:49 PM EDT     Moonrise
Fri -- 06:43 PM EDT     0.08 feet Low Tide
Fri -- 08:08 PM EDT     Sunset
Tide / Current data from XTide NOT FOR NAVIGATION

Bannermans Branch, Northeast River, North Carolina, Tide feet

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