textproduct: Wakefield

WHAT HAS CHANGED

Updated discussion, minimal changes to the forecast.

KEY MESSAGES

1) Scattered showers increase in coverage, with numerous showers and storms expected later today. Heavy rainfall is likely in any storm, with localized flash flooding possible in urban and flood prone areas.

2) Additional chances for showers and storms capable of heavy rainfall are expected Tuesday and Wednesday.

3) Drier weather returns to end the week.

DISCUSSION

As of 1145 AM EDT Monday...

KEY MESSAGE 1...Scattered showers increase in coverage, with numerous showers and storms expected later today. Heavy rainfall is likely in any storm, with localized flash flooding possible in urban and flood prone areas.

Latest analysis indicates the sfc front now North of the CWA, with the winds having shifted to the SW even on the MD eastern shore. It remains mostly cloudy aside from SE VA/ NE NC where the sky is variably cloudy. Most areas have temperatures ranging through the 70s with dew pts around 70F, though readings have risen into the lower 80s over much of SE VA and NE NC, with dew pts in the low- mid 70s. Area 12Z soundings observed PWAT values from ~1.75" to ~1.85", so moisture is markedly increased compared to the past few days. Overall, instability parameters, while much more unstable compared to Saturday- Sunday, are still not impressive, especially across the NW 1/2 of the area where the sky has been mainly overcast with periodic light showers so far. CAPE is higher in the SE, and can see the response with numerous showers now filling in there. These showers are moving so even with decent rainfall rates, amounts have been fairly minimal on average. Over the next few hrs, expect to see somewhat heavier showers and some embedded tstms, mainly across the SE.

Heavy rainfall is likely given deeply-saturated profiles seen in model soundings, with PWATs progged to approach 2" for a good portion of central and eastern VA (and NE NC) by late aftn. The consensus from the 12Z HREF and REFS places the corridor of highest QPF across the SE through ~21Z, with that region seeing somewhat less QPF after 21Z, as the highest axis of heavy rain shifts to roughly from the I-85 corridor northeastward into the RIC metro and Northern Neck. While antecedent rainfall conditions are not favorable for widespread flash flooding, some issues could develop in urban and flood prone areas if 1-2" falls in a short period, along with any repeated training of moderate-heavy showers/storms that occurs. There was additional discussion with WPC on upgrading portions of the region to a slight risk for excessive rainfall. However, given the overall flooding threat is mitigated by the dry antecedent conditions (and with little rainfall Sunday), expect the flash flood risk to be confined to these aforementioned locations, and therefore, the marginal risk has been maintained. Highs will average in the mid 70s NW to the low-mid 80s SE. Widespread precip and rain-cooled air likely drops temps back into the lower 70s.

Showers likely persist into the evening and early overnight hours, with a continued threat of heavy rainfall. However, the thunderstorm potential will be much lower given dwindling instability.

KEY MESSAGE 2...Additional chances for showers and storms capable of heavy rainfall are expected Tuesday and Wednesday.

The frontal boundary remains near the area Tuesday and Wednesday, which will focus additional shower/storm development over the local area. The exact position of the front will dictate where the heaviest rainfall falls and also where storms are favored. Surface- based instability (and storms) are likely along and S of the front, with much lower storm chances to the N. Model guidance is not currently in good agreement on the frontal positioning (particularly on Tuesday) with solutions varying from well N of the area to bisecting our CWA. Given these uncertainties, a chance for showers/storms has been maintained for the entire area, highest for southern VA and the Piedmont and lower from the Northern Neck onto the MD Eastern Shore. Anomalously high PWATs again favor a heavy rainfall threat. A stronger storm or two is also possible, but the severe threat is quite low given meager lapse rates and only modest shear. The front's location also has implications on the temperature forecast. At this point, the warmest temps on Tuesday are favored from southern VA into NC, though the gradient will probably be a bit more than currently indicated in the forecast. Warmer areawide Wednesday with highs well into the mid 80s possible.

KEY MESSAGE 3...Drier weather returns to end the week.

A cold front will move through Wednesday night as a trough digs out of Eastern Canada into the Northeast CONUS. The main impact from this will be an influx of drier air and little to no precip chances. In fact, forecast high temperatures (well into the 80s) are similar or even a bit higher Thursday vs Wednesday. "Cooler" air arrives by Friday with highs in the upper 70s to around 80 F.

There is increased uncertainty by the weekend as another trough digs out of Canada and potentially interacts with an active southern stream. Rain chances could thus return by Saturday and Sunday, particularly for the southern half of our forecast area. High temps generally in the 70s.

AVIATION /15Z MONDAY THROUGH FRIDAY/

As of 700 AM EDT Monday...

Degraded flight conditions remain in place at ORF, PHF, RIC, and SBY this morning with either low-end MVFR or IFR CIGs and locally reduced VSBY. ECG has recently improved to VFR. Gradual improvement in the CIGs is expected today, but only to MVFR. There is also some possibility IFR persists at SBY through the period. Scattered- numerous showers/tstms are also expected by this afternoon and evening. Brief gusty winds, lightning, and heavy rain/VSBY reductions are the main threats from these storms. Winds through the period will generally average S-SW and be less than 10 kt. Further degradation to IFR/LIFR is expected again tonight with continuing shower chances.

Outlook: Conditions remain unsettled with off and on showers and storms and sub-VFR conditions continuing into the middle of the week.

MARINE

As of 830 PM EDT Sunday...

Key Messages:

- A Marine Dense Fog Advisory remains in effect for the coastal waters north of Parramore Island through 10 AM. - Sub-SCA SSW winds prevail today, with a weak cold front leading to light and variable winds Tuesday, then sub-SCA SW winds returning Wednesday.

High pressure is centered offshore early this morning with a weak stationary front lingering in vicinity of the lower Ches. Bay and VA Capes. The wind is mainly light and out of the N-NE to the north of the boundary and out of the SSW south of the boundary. Seas have subsided to 3-4ft in the coastal waters, so lingering SCAs for the northern coastal waters will expire at 4AM. Vsby is once again deteriorating across the northern coastal waters, so the Marine Dense Fog Advisory will remain in effect through 10 AM.

The front is expected to slowly move north as a warm front today into tonight with the wind becoming SSW 8-12kt. This boundary then settles south Tuesday with the wind remaining light, but shifting to E/NE across the northern tier of the marine area. The front then lifts back to the north Tuesday night into Wednesday with light SW flow developing. Seas in the coastal waters will subside from 3-4ft initially to 2-3ft by Tuesday and Wednesday, with offshore seas subsiding from 4-5ft to 3-4ft. Waves in the Ches. Bay will be ~1ft with light flow, and 1-2ft near the mouth of the Bay.

A cold front moves N-S across the Mid-Atlantic coast late Wednesday night into early Thursday with the wind becoming northerly, but remaining sub-SCA. A stronger cold front potentially crosses the coast next weekend with a N/NE wind developing behind the boundary, which would also result in elevated seas. SCA conditions are possible in the wake of this front.

AKQ WATCHES/WARNINGS/ADVISORIES

MD...None. NC...None. VA...None. MARINE...Dense Fog Advisory until 7 AM EDT Tuesday for ANZ650-652.