ZCZC SPCSWOMCD ALL ACUS11 KWNS 131707 SPC MCD 131707 MAZ000-RIZ000-CTZ000-NYZ000-NJZ000-PAZ000-131900- Mesoscale Discussion 1945 NWS Storm Prediction Center Norman OK 1107 AM CST Sat Nov 13 2021 Areas affected...Parts of New Jersey...southeastern New York...Long Island...Connecticut...Rhode Island and Massachusetts Concerning...Severe potential...Watch likely Valid 131707Z - 131900Z Probability of Watch Issuance...80 percent SUMMARY...Showers and thunderstorms are expected to intensify across the region, spreading from near northern Mid Atlantic coastal areas into southern New England, accompanied by increasing risk for potentially damaging wind gusts and perhaps a couple of tornadoes through late afternoon. DISCUSSION...Although details differ considerably among the various models, it seems probable that surface low pressure will begin to consolidate across parts of central New Jersey into the western Long Island vicinity by mid afternoon, before deepening while continuing to track east-northeastward across southeastern New England through 22-00Z. This is expected in response to strengthening large-scale forcing for ascent, ahead of a vigorous short wave trough currently pivoting across the northern Virginia/central Maryland vicinity. It appears that this will include intensifying lift within a corridor along and ahead of an associated cold front, preceded by at least weak destabilization within an expanding warm sector across parts of southeastern New England. It is uncertain whether destabilization will be sufficient to support discrete storm development ahead of the east-northeastward surging cold front, but the evolution of at least a narrow line of low-topped convection seems probable in response to the enhanced mesoscale lift. Likely located along/just north of a belt of 70-90+ kt flow around the 500 mb level, cloud bearing layer shear will be quite strong and more than sufficient to contribute to organized convection with the potential to produce small hail and potentially damaging wind gusts. Low-level wind fields are initially relatively modest, with pre-frontal southerly 850 mb flow still around 30 kt, and this could slow the development of increasing potential for severe wind gusts. However, guidance generally indicates that substantive further strengthening of this flow to 40-50+ kt is possible, particularly by late afternoon across parts of eastern Long Island into southeastern New England, where enlarging low-level hodographs might become conducive to a risk for tornadoes, in addition to increasing potential for severe wind gusts. ..Kerr/Hart.. 11/13/2021 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...BOX...OKX...ALY...PHI... LAT...LON 40777469 41367455 42337294 42307120 40817136 39797396 39907475 40777469 NNNN