Sunrise 6:15 AM   Sunset 8:06 PM Moonrise 3:42 AM   Moonset 4:29 PM

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FXUS62 KRAH 051042 RRA AFDRAH

Area Forecast Discussion National Weather Service Raleigh NC 640 AM EDT Sun May 5 2024

SYNOPSIS
A quasi-stationary front across the area this morning will retreat northward through the afternoon as a series of mid and upper-level disturbances traverse the area. A low amplitude shortwave trough will progress east into the area late Monday and into Tuesday, bringing additional chances of showers and storms. Drier conditions are expected by mid week, leading to increasing heat as upper level ridging returns.



NEAR TERM /THROUGH TONIGHT/
As of 330 AM Sunday...

Unsettled Conditions Continue Today

The next wave of shortwave impulses, with an embedded MCV over upstate SC, will cross central NC through the afternoon. A prominent band of moderate rain showers, with some embedded lightning potential, is accompanying this feature and has moved into the western Piedmont of the Carolinas. This band will progress slowly eastward through the morning and afternoon hours. Outside of this primary convective rain band, additional showers and thunderstorms will likely develop but should be more scattered in nature through the remainder of the afternoon and evening. While weak elevated instability exists area-wide to support thunder, the quasi- stationary front bisecting the area has significantly muted surface base instability across the northern half of the forecast area(along and north of HWY 64). Thus, the best chance of thunder through daybreak will be south of the front, across our southern counties.
Thereafter, tempered heating/insolation should result in more equitable thunder chances as weak sfc base instability of 500-1000 J/kg develops across the area, though the primary convective band should continue to provide the best forcing.

Latest forecast guidance suggests the stalled front draped across the area may linger a bit longer than previous forecasts suggested.
Thus, it's not surprising to see models trending cooler across the northern counties. Highs ranging from lower/mid 70s north to around 80 south.

Convection should largely wane/diminish after sunset, with what appears to be lull/intermission from the upper disturbances and waves. The airmass remains very moist however and models indicate the potential for some isolated convection overnight. Cloudy and mild overnight with temps in the 60s as stratus re-develops across the area.



SHORT TERM /MONDAY AND MONDAY NIGHT/
As of 330 AM Sunday...

Elevated Rain/Storms Chances Again Monday

The southern stream shortwave trough associated with the expansive MCS over the southern Plains and Texas will become increasingly sheared as it ejects eastward across the middle MS and Tn Valley Monday afternoon and then across the central and southern Appalachians and into mid-Atlantic region Monday evening and night.
Renewed moisture advection ahead of this wave will lead to a resurgence of anomalous moisture into the region with PWATs 1.6-1.8, near record daily maximum.

Stronger daytime heating should result in more robust instability of 1000-2000 J/Kg across the area. There is the potential for an area of deep moist convection(DC) to propagate east into and across the area during the afternoon and early evening, with additional development possible along convective outflow. Shear will increase slightly, with models indicating a pocket of enhanced shear of 25- 30kts along the potential DC feature. Thus, cannot rule out an isolated severe cluster or two Monday afternoon and evening. Storms intensity and coverage should decrease after sunset, with some lingers isolated showers possible Monday night.

Highs 80-85. Lows in the 60s.

LONG TERM /TUESDAY THROUGH SATURDAY/
As of 245 AM Sunday...

An active pattern persists in the extended, particularly the latter portion of the week with several chances for showers and storms.
Somewhat drier conditions will start the period, along with temperatures well above average, followed by near to possibly below normal highs by the weekend.

Tuesday will feature a weakened shortwave trough from Mon over VA/NC, with the axis roughly along/east of the Coastal Plain. With time, the trough will move out over the coast by the evening, with ridging building in Tue night/early Wed. There is not much forcing outside of the trough. However, most models indicate weak capping and 1000-1500 J/kg of MLCAPE, maximized over the Sandhills, eastern Piedmont and Coastal Plain. This along with 20-25 kt of shear should favor isolated/scattered activity over the region, which could interact with a sea-breeze. Suspicion is that activity would be largely focused east of US-1, but activity could occur just about anywhere. Highs should turn warmer and above average in the 80s.

Ridging Tue gives way to an increasingly perturbed southwest flow aloft for the latter part of the week with troughing over the Plains and ridging over the Gulf. As we go into Wed and especially Thu/Fri, models/ensembles indicate that the trough will slowly migrate ESE into the Great Lakes and OH valley region, eventually reaching the Mid-Atlantic by the weekend. At the surface, lee troughing will gradually give way to a cold front trying to make its way through late Fri or early Sat. Upstream convection Wed/Thu over the Midwest/southern Plain complicate the exact timing/location of these perturbations in the southwest flow. Shortwave energy could arrive as early as Wed night, with the GFS/GEFS showing more influence from the trough versus the EC/GEPS. Better agreement, though, is noted Thu/Fri where additional perturbations impact the region as the trough/front inch closer. All of this is to say that we cannot fully rule out a chance of storms Wed/Wed night, and storm chances will remain Thu/Fri, albeit with low confidence on timing/location given model spread on shortwave features. With increasing shear and higher instability Thu/Fri in the strong kinematic flow, severe storms are possible ahead of a convectively reinforced boundary slowly sliding eastward from the TN valley. Wed/Thu should still hover well above average in the mid/upper 80s to low 90s, though given the uncertainty in upper-level features, the NBM 90+ degree probabilities are highest at 50-60% on Wed.

By Sat, model solutions still show spread in the location of the trough, with the GFS/GEFS/GEPS faster than the EC, which keeps the main trough over the Great Lakes OH Valley versus near Long Island in the former solutions. A drier pattern appears favored with NW flow, but upstream energy in the EC could favor low-end stratiform rain chances. Highs are currently expected to trend closer to normal or a touch below in the 70s.

AVIATION /11Z SUNDAY THROUGH THURSDAY/
As of 640 AM Sunday...

Upper level disturbances interacting with anomalously moist air in place will continue to result in adverse aviation conditions through the forecast period.

A band of moderate showers with the potential for some embedded lightning currently over western and central Piedmont of NC will progress slowly eastward through the remainder of the morning and afternoon hours, and should impact all terminals through 21z.
Additional showers and thunderstorms will likely develop outside of the primary band, but should be more scattered in nature through the remainder of the afternoon and evening.

Expect gradual lifting of the widespread LIFR to MVFR as the front draped across the area begins to lift north. Outside of any convection, flight conditions should lift to VFR at KFAY and KRWI during the late morning and early afternoon. KGSO, KINT, and KRDU will also show some improvement, but could very likely remain MVFR through the afternoon and evening.

Widespread LIFR to MVFR restrictions are expected to re-develop Sunday evening/night.

Outlook: Scattered to numerous showers and storms are expected again Monday. Rain chances should become more diurnal and scattered in nature Tuesday and Wednesday. Continued moist air will support the potential for restrictions associated with widespread fog and/or low clouds each morning

RAH WATCHES/WARNINGS/ADVISORIES
None.

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