← Previous March 31, 2023 12:44 PM
ACUS02 KWNS 311746 SWODY2 SPC AC 311744 Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1244 PM CDT Fri Mar 31 2023 Valid 011200Z - 021200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS OVER MUCH OF THE NORTHEAST...AND OVER PARTS OF THE SOUTHEAST.... ...SUMMARY... Damaging winds are expected across parts of the Northeast Saturday during the day and through early evening. Other severe storms will be possible over parts of the Southeast. ...Synopsis... A large shortwave-trough will move across the Upper Great Lakes and OH Valley to the Mid Atlantic by 00Z, with substantial height falls/cooling aloft overspread the entire region. An intense leading midlevel jet streak will approach the Appalachians by midday, with a secondary cold pocket and vort max aloft affecting the I-95 corridor late in the day. To the south, moderate westerlies aloft will exist over the Southeast, as the influence of the upper trough grazes the area. At the surface, low pressure should gradually deepen as it moves east/northeast from southwest Ontario toward northern ME. Extending east of the low track will be a developing warm front which will bring 50s F dewpoints into southern VT/NH and perhaps ME. Although the primary surface low will move toward more stable areas to the north, a prominent surface trough will develop southward coincident with the secondary vort max moving rapidly east. While various regimes of severe weather may occur with these features, this secondary wave will affect the Mid Atlantic late in the day and into early evening, and is expected to result in wind damage from western MA and CT into far eastern PA, all of NJ, and parts of the Delmarva. A few tornadoes may occur over southern parts of this region. Farther south, a front/dryline will slow as it moves into southern AL and across GA during the day, with a more substantial cold front pushing east across VA and the Carolinas. Scattered severe storms are possible across these areas during the day. ...From eastern OH into New England... The initial severe risk on Saturday will likely be tied to the leading vort max associated with left-front quadrant of the midlevel jet. Cold temperatures aloft will result in 250-500 J/kg SBCAPE in the corridor from eastern OH/western PA across much of NY and into New England by late afternoon. The combination of very steep, deep-layer lapse rates along with increasing boundary-layer wind speeds suggest any convection at all will have the potential to enhance downward mixing. This seems likely given expected sufficient instability. The northward extent of this damaging wind regime will be limited by the warm front, and it is possible that this boundary eventually makes it into extreme southern ME. ...From the Delmarva across NJ and into southern New England... Southerly surface winds for most of the day will help deepen the moist boundary layer, with a plume of upper 50s F to near 60 F dewpoints from eastern VA northward across Philadelphia and into far southeast NY. Strong heating will occur along and west of this moist plume, priming the air mass for the arrival of an intense cold front arrive very late in the day and into early evening for eastern areas. Forecast soundings reveal supercell wind profiles with effective SRH over 300 m2/s2, and long hodographs as well. The forecast is for storms to form in the moist axis as the front rapidly intercepts the moist air mass, with rapid changes taking place aloft. Some of these storms could develop along coastal counties as well, and at least isolated supercells are expected. A conditional tornado risk will exist where SBCAPE remains favorable, centered over NJ and DE. Damaging winds will be quite likely with any strong convection given 50+ kt winds out of the northwest just off the surface. Clearly, these will be able to mix to the surface. Various models appear to be struggling with this area, thus there is uncertainty in the magnitude of the severe risk. ...Southern GA into the eastern Carolinas... Scattered showers and a few thunderstorms may be ongoing ahead of the surface boundary early in the day, beneath southwesterly 50 kt 850 mb flow and within a theta-e plume. Strong heating is expected near the synoptic boundary and deepening surface trough, and the presence of mid 60s F dewpoints will lead to ample instability to support daytime storms despite lack of upper support. With time, storms along the boundary may develop into supercells as deep-layer shear will be strong and effective SRH averages 150-200 m2/s2. Any supercell/tornado threat is expected to be limited as midlevel subsidence occurs, but sporadic hail, a brief tornado, and damaging gusts will all be possible through the afternoon. Rapid drying from the west should push the severe threat quickly eastward across the region and to the eastern Carolinas before 00Z. ..Jewell.. 03/31/2023 $$