textproduct: Wakefield

WHAT HAS CHANGED

Rain chances have increased for Tuesday mainly south of I-64.

KEY MESSAGES

1) An unsettled pattern prevails through midweek. Near average temperatures, humid conditions, and daily chances of showers and storms are expected.

2) A more typical summertime pattern returns for the latter half of the week. Isolated to scattered afternoon showers and thunderstorms remain possible, with near to slightly above normal temperatures prevailing through the weekend.

DISCUSSION

As of 300 PM EDT Monday...

KEY MESSAGE 1...An unsettled pattern prevails through midweek. Near average temperatures, humid conditions, and daily chances of showers and storms are expected.

Latest surface analysis depicted a cold front beginning to push into NW VA early this afternoon. Scattered showers and storms are beginning to develop along this front and are expected to gradually move SE into this evening with the slow FROPA. Models are in decent agreement with this line of showers and storms persisting through at least this evening and perhaps continuing into late tonight. HREF even maintains a 10% chance for 3"/3hr of rainfall across central VA through 11 PM. Will note that this area is in a locally lower PW (precipitable water) environment of 1.6-1.8" (as opposed to 2.2-2.3" across extreme SE VA/NE NC) given some dry air entrainment with the cold front. This should limit the flash flooding risk today/tonight. However, with slow storm motions, the potential for risking PWs after sunset, and the potential for convection to linger around the Richmond Metro this evening (where flash flood guidance is only 1- 2"/1 hr and ~2"/3 hr, locally heavy rain and localized flash flooding remains possible. An additional area of scattered storms has developed across extreme SE VA/NE NC in association with an upper level trough centered across the Southeast. This convection is expected to move NE through the afternoon before tapering off this evening. Given the aforementioned locally higher PW environment in this region, locally heavy rainfall is possible. However, flash flood guidance is higher in this region (2.5-3"/1 hr) which leads to low confidence in reaching flash flooding criteria.

The cold front stalls near the VA/NC tonight/Tuesday morning before slowly lifting back north through the day Tuesday. Meanwhile, an upper level low becomes a cutoff low Tuesday across the southern Appalachians. This should help a weak surface low to form across the Carolinas Tuesday before lifting north into central VA tonight. Given the W/E oriented front, surface winds should remain backed (predominantly E) through the day on Tuesday with dew points remaining in the mid (locally upper) 70s. This should allow for enough instability (MLCAPE ~1500 J/kg) for scattered to widespread showers and thunderstorms to develop Tuesday afternoon across southern/south- central VA and interior NE NC. PWs rise to 2.2-2.5 across the area. These high PWs combined with tall/skinny CAPE, slow storm motion, and a nearly stationary front will likely lead to widespread showers and storms Tuesday afternoon into Tuesday evening. The aforementioned environment is favorable for locally heavy rainfall and isolated flash flooding. HREF probs for 3"/3hr increase to 30% generally south of I-64 during the afternoon. While normally this would be a borderline flood watch environment, the region of heaviest rainfall appears to be mainly south of Richmond and west of the Hampton Roads region in an area of locally higher flash flood guidance (2.5-3"/1 hr and 3"+/3 hr). As such, the flash flooding risk is more likely to be isolated in nature (as opposed to scattered). Convection tapers off from south to north Tue night.

Confidence is lower for widespread convection Wednesday afternoon. If widespread convection does occur on Tuesday, the environment may be too overturned to allow for much more than isolated to locally scattered showers and storms on Wednesday. However, given that Wednesday is still several days away and given that most CAMs do not go out that far, have kept NBM PoPs for Wed (for now). That being said, NBM PoPs appear high compared to what the general model consensus has been. If models continue to not show much in the way of convection for Wednesday, will likely need to lower PoPs.

Given the moist environment (and lack of DCAPE), relatively weak flow aloft, and tall/skinny CAPE, the main threat over the next few days will be locally heavy rain and flash flooding. As such, there is a marginal risk for excessive rainfall across most of the area today through Wednesday. Meanwhile, the Storm Prediction Center (SPC) is not currently anticipating severe weather. Nevertheless, a few wet downbursts with mainly sub-severe storms are possible. Otherwise, high temperatures dip down slightly below average Tuesday with near average temperatures expected on Wednesday.

KEY MESSAGE 2...A more typical summertime pattern returns for the latter half of the week. Isolated to scattered afternoon showers and thunderstorms remain possible, with near to slightly above normal temperatures prevailing through the weekend.

Though not as unsettled as the first half of the week, the latter half of the week will see isolated to scattered diurnally driven showers and thunderstorms. However, coverage in storms is expected to be much lower on Thu and Friday with most areas remaining dry. Nevertheless, WPC has a marginal risk for excessive rainfall across NE NC on Thursday and across most of the area of Friday. With the decreased convective coverage forecast, temperatures will return to near to slightly above normal with highs in the upper 80s to lower 90s. Dew points will remain in the mid (locally upper) 70s. This will allow for humid conditions to continue. Heat indices around 100 degrees are expected for most of the area Thursday through Sunday. However, given temperatures remaining near normal, heat headlines are not expected at this time.

AVIATION /18Z MONDAY THROUGH SATURDAY/

As of 155 PM EDT Monday...

CIGs were mainly MVFR/VFR this afternoon with an improvement to predominantly VFR CIGs expected later this afternoon into this evening. Scattered storms were noted across extreme SE VA/NE NC early this afternoon. This convection should move NE through the afternoon before dissipating this evening. Given greater instability across NE NC and the presence of lightning with current convection, have added thunderstorms to the ECG TAF for the next few hours. Confidence in thunder diminishes farther north. As such, have kept showers mentioned in the TAFs for the other terminals. A cold front approaches from the NW this afternoon, slowly moving into the local area later this afternoon into tonight before stalling near the VA/NC border. Scattered showers and storms have already begun to develop along the front and are expected to continue to slowly push SE into tonight. As such, shower chances linger through late tonight inland. However, confidence in thunder at RIC was too low to add to the TAF at this time. Additional scattered to widespread showers (with embedded storms) are likely Tue afternoon mainly along and south of I-64. Otherwise, CIGs drop to mainly MVFR after midnight tonight, lingering through the day on Tue. Additionally, some model guidance suggests that IFR CIGs are possible at ORF/PHF from around 10-14z Tue. As such, have added IFR CIGs to the TAFs for those two terminals.

Outlook: Elevated shower/storm chances continue through mid- week, with periodic flight restrictions lingering, mainly from early morning stratus, and brief visibility restrictions in heavy rain. A more typical Summer pattern returns for the latter half of the week, with a somewhat lower coverage of late afternoon and evening isolated to scattered showers and storms Thu-Fri.

MARINE

As of 230 PM EDT Monday...

Key Messages:

- Small Craft Advisories remain in effect coastal waters into this evening.

- Benign marine conditions are expected to prevail from late tonight through late week, outside of local thunderstorm influences.

Latest analysis reveals 1024+ mb high pressure anchored well offshore. To the west, low pressure was analyzed over southern Quebec as of this writing, with a weak surface cold front in place from the Eastern Great Lakes, well west of the local waters and extending into the western Carolinas and Deep South. Ahead of the front, S-SW winds of 10-15 kt this afternoon will diminish further tonight as the pressure gradient slackens with the weakening front lingering to the west. Winds veer around to the NNE ~10 kt over northern and central waters, as the front slowly slides into the area, remaining SSE for the lower Bay and southernmost coastal waters. Waves 1-2 ft/Seas 5-7 ft slowly subside from S to N late this afternoon into the evening, diminishing to 1 ft/2-4 ft by late tonight and Tuesday. SCAs have been extended into late tonight north of Parramore Island, and continue into this evening from Parramore Island south to Currituck Light.

Widespread organized convection is not expected, though additional isolated to widely scattered showers are possible this evening, with more widespread storms tomorrow, as the front drifts closer to the local area. Locally degraded marine conditions are likely to accompany the stronger storms through the week, mainly in the form of VSBY restrictions in heavy rain and frequent lightning, but some marginally severe gusty winds will also be possible.

The front washes out through midweek, with weak high pressure rebuilding over the area, then sliding offshore for late week. A more typical summer setup resumes, with Sub-SCA S-SW winds ~10-15 kt developing, turning S-SE nearshore with seabreeze circulations each afternoon. Daily afternoon and evening shower and storm chances persist into the weekend, though chances gradually diminish beyond Wednesday.

Rip Currents: There is a Moderate Rip risk for the northern beaches tomorrow with a Low Rip Risk for southern beaches.

AKQ WATCHES/WARNINGS/ADVISORIES

MD...None. NC...None. VA...None. MARINE...Small Craft Advisory until 1 AM EDT Tuesday for ANZ650-652-654. Small Craft Advisory until 10 PM EDT this evening for ANZ656- 658.