textproduct: Wakefield

WHAT HAS CHANGED

Updated discussion. SPC has trimmed the Slight (Level 2/5) Risk slightly and it only remains in place from Louisa to part of the Lower MD Eastern Shore. The Marginal (Level 1/5) Risk has also been trimmed and only includes areas down to I-64. A strong cold front is still expected to cross the area Wed night into Thurs AM, bringing additional showers and a change in airmass. A Gale Watch remains in effect for Thursday for the mouth of the Chesapeake Bay, and the Ocean between Cape Charles and Currituck Beach Light.

KEY MESSAGES

1) Record warmth is expected again today, with upper 80s forecast for portions of the area. Any thunderstorm development most likely remains to our north and west this afternoon and evening. There is a 20-30% of thunderstorms across northern portions of the area. However, if storms do develop, they will likely be strong to severe with damaging winds and perhaps large hail.

2) A stronger cold front crosses the area Thursday morning-midday, bringing a very good chance of rain, along with a low-end potential for some stronger storms during the first part of Thursday. A few snowflakes may mix in Thursday afternoon but no accumulation is expected. Cooler temperatures and dry weather return to end the week.

DISCUSSION

As of 235 AM EDT Wednesday...

KEY MESSAGE 1...Record warmth is expected again today, with upper 80s forecast for portions of the area. Any thunderstorm development most likely remains to our north and west this afternoon and evening. There is a 20-30% of thunderstorms across northern portions of the area. However, if storms do develop, they will likely be strong to severe with damaging winds and perhaps large hail.

Early morning wx analysis shows a northern stream low pressure system tracking across the Great Lakes with a southern stream system over Texas. The flow aloft is WSW over the Mid-Atlantic ahead of these two systems. Very mild with temps in the 60s at this hour with a light southerly breeze. Record warmth is expected again today with high confidence in record highs for at least some of our climate sites. Upper 80s are possible inland, with lower-mid 80s likely for much of the area. The northern stream low deepens as it tracks NE toward the Saint Lawrence Valley by late today, and it will drag a cold front toward the region. While the best mid/upper height falls and stronger upper level dynamics from the approaching trough remain to our north and west today, the very warm temperatures and lower- mid 60s dew points will allow for 500-1250 J/kg of MLCAPE to develop by the mid to late afternoon. In addition, the 500mb flow will increase to 50-60 kt over far northern portions of the FA. However, there will be a cap around 750-850mb that will need to be broken for convection to develop this afternoon/evening. For what it's worth, the 00z guidance has trended farther north with tstms and none of the operational models (including the CAMs and RRFS) have any sort of convection over the area today as they are forecasting the cap to hold strong. Nevertheless, still think there is about a 20-30% chance of convective initiation from Louisa/Fluvanna Counties to the northern neck and MD Eastern Shore. If storms break the cap and develop, they will likely be strong to severe with damaging winds being the main threat, though large hail and even a brief tornado possible given ~100 m2/s2 of 0-1 km SRH. While confidence in storm initiation continues to be quite low, this setup will continue to be monitored. Given the trends in the 00z guidance, SPC has trimmed the Slight (Level 2/5) Risk slightly and it only remains in place from Louisa to part of the Lower MD Eastern Shore. The Marginal (Level 1/5) Risk has also been trimmed and only includes areas down to I- 64.

KEY MESSAGE 2...A stronger cold front crosses the area Thursday morning-midday, bringing a very good chance of rain, along with a low-end potential for some stronger storms during the first part of Thursday. A few snowflakes may mix in Thursday afternoon but no accumulation is expected. Cooler temperatures and dry weather return to end the week.

The above mentioned southern stream low pressure system tracks across the Gulf today before moving into the Carolinas Thursday. Meanwhile to the north, the potential sub-990mb northern stream low is expected to drag a strong cold front through the local area Thursday AM to midday. The vast majority of the precipitation associated with the front is progged to fall behind the front with the best precip chances from late morning-early evening as that southern stream system tracks just to our south. Temps will not drop much below 70F prior to the FROPA Thu AM as winds veer from the S to SW.

Temperatures will likely warm a couple degrees across SE VA/NE NC Thurs AM before the cold front moves through. Dew pts will actually fall a few degrees tonight with the winds veering to the SW just ahead of the front. So not expecting any sfc-based instability later tonight. However, as the front crosses SE VA/NE NC between 9 AM-1 PM Thursday, some destabilization is possible ahead of the frontal boundary with the onset of daytime heating (temps warm into the mid 70s). This could lead to the development of a narrow line of gusty showers just ahead of the front, which could easily bring ~40 mph gusts. However, confidence in gusts approaching severe levels (50 kt) remains very low at this time. Regardless of any convection, a few hours worth of 30-40 mph gusts are likely across much of the area as winds become NW right behind the front. Temps are expected to drop from around 70F to the 40s very quickly following the FROPA. In fact, some areas could drop into the mid-upper 30s Thu aftn and a few wet snowflakes could mix in toward the tail end of the precip. A brief period of light snow cannot be completely ruled out. However, no accumulation is expected. Even though some of the ensembles have trended upward with respect to snow QPF and show notable probabilities of 1" of snow at a 10:1 ratio, this would very likely all melt when it hits the ground given the warm antecedent conditions and snow rates that are not that impressive. With the strong front coming through, high temperatures shown in the forecast are likely to be achieved early in the day, with those falling temps as the day proceeds.

Looking through the extended, seasonably cooler and dry weather returns Friday, with highs dropping back into the 50s despite plentiful sunshine. Milder conditions with temps approaching 70 F are forecasted by the weekend as transient high pressure slides over, also supporting continued mainly dry wx. Another low pressure system and cold front brings a good chance of showers (with perhaps an isolated tstm) to the area on Monday.

AVIATION /09Z WEDNESDAY THROUGH SUNDAY/

As of 530 AM EDT Wednesday...

VFR conditions will prevail at all terminals through the TAF period. ECG has seen some ground fog during the past couple of hours, and expect this to persist through 12-13z. Otherwise, S-SW winds will start to pick up by midday into the early afternoon, with gusts of 20-25 kts expected through the evening. There is a slight chance for thunderstorms (mainly at SBY) between 22-03z, but convection most likely stays north and west of the terminals. Confidence is too low to include thunder in the TAF attm. A strong cold front approaches tonight and crosses the terminals Thursday morning- midday. A period of LLWS is likely at all terminals for a few hours before the front arrives. Winds abruptly become NW following the FROPA with a brief gusts to 30-35 kt possible. Rain continues for several hours behind the front on Thu with MVFR to IFR conditions likely. There is a low chc of a rain/snow mix at all terminals except ECG Thu aftn, but no accums or operational impacts are expected.

Outlook: VFR conditions return Thursday night and persist into Saturday.

MARINE

As of 310 AM EDT Wednesday...

- Small Craft Advisories have been issued for the Chesapeake Bay, tidal rivers, and northern coastal waters from this evening into Thursday.

- Gale Watch timing has been pushed a few hours later for both start and end times and now also includes the Currituck Sound along with to the mouth of the bay and southern coastal Atlantic waters.

Broad low pressure is noted from the southern Plains northeastward into the Midwest early this morning. Surface low pressure deepens near the Great Lakes today which will slowly tighten the pressure gradient over the local waters. Southerly winds mainly 10-15 kt today, becoming SSW/SW and increasing to 15-20 kt with gusts to 25 kt this evening into the overnight hours. Cool near-shore waters will limit mixing today but the synoptic gradient will steadily sharpen this evening. SCA headlines have been issued for the Ches Bay, rivers, and Atlantic coastal waters north of Cape Charles Light from this evening through early Thursday evening. 00z guidance has trended toward slightly slower timing for the strong cold front to cross the waters. Still expect this very strong front to be near the northern waters by sunrise Thursday and be south of the area by early Thursday afternoon. In coordination with the Morehead City WFO, opted to not upgrade the Gale Watches to Gale Warnings with this forecast package. That said, 00z guidance continues to show very impressive pressure rises (9-12mb in 6 hours) immediately behind the cold front and winds could gust aoa 35 kt as the boundary comes through. It still appears that the best chance for prolonged gusts in this range will be focused across the southern third of the area from mid morning through late afternoon. This includes the mouth of the bay, Currituck Sound, and Atlantic coastal waters south of Cape Charles Light. Gale Watch headlines have been adjusted accordingly. Elsewhere, the period of post-frontal 30-35 kt gusts will be shorter and will likely be handled with short-fuse SMWs as needed. The gradient begins to relax Thursday afternoon and especially during the evening and overnight hours.

Seas will build to 4-6 ft N and 3-5 ft S in the pre-frontal SW flow but should fall off quickly Thursday afternoon as flow turns offshore, the exception being in the Gale Watch area of the Ocean where seas may briefly build as high as 6-7 ft. Waves in the Chesapeake Bay will increase to 2-4 ft ahead of the front and reach to 3-5 ft through much of Thursday during the stronger NNW winds. Another system moves by well to the north on Friday with potential for another period of SCA conditions.

CLIMATE

As of 230 AM EDT Wednesday...

Record highs were set at ORF (83F), RIC (85F), and SBY (83F), while the record high was tied at ECG (82F) yesterday. Both record highs and record high mins are likely for today (3/11).

- Record High Temps for today (3/11)

Record High/Year Location 3/11 -------- ---- Richmond 82 (1990) Norfolk 82 (1990) Salisbury 76 (2000) Eliz. City 81 (2016)

- Record High Min Temps for today (3/11)

Location Rec High Min -------- ------------ - Richmond 56 (1955) - Norfolk 62 (1925) - Salisbury 51 (1955) - Eliz. City 58 (1967)

AKQ WATCHES/WARNINGS/ADVISORIES

MD...None. NC...None. VA...None. MARINE...Small Craft Advisory from 7 PM this evening to 7 PM EDT Thursday for ANZ630>632-638-650-652-654. Gale Watch from Thursday afternoon through Thursday evening for ANZ633. Small Craft Advisory from 7 PM this evening to 10 AM EDT Thursday for ANZ634. Gale Watch from Thursday morning through Thursday afternoon for ANZ634. Small Craft Advisory from 10 PM this evening to 7 PM EDT Thursday for ANZ635>637. Gale Watch from Thursday morning through Thursday evening for ANZ656-658.