Subj : MESO: Nws Weather Prediction Center College Park Md To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Fri Dec 23 2022 09:59:30 AWUS01 KWNH 230959 FFGMPD MEZ000-MAZ000-NHZ000-VTZ000-CTZ000-NYZ000-NJZ000-231557- Mesoscale Precipitation Discussion 1166 NWS Weather Prediction Center College Park MD 458 AM EST Fri Dec 23 2022 Areas affected...Eastern New York through Central and Southern New England Concerning...Heavy rainfall...Flash flooding possible Valid 230957Z - 231557Z SUMMARY...Heavy rains continuing to move north across eastern New York and central/southern New England will couple with melting snow to encourage concerns for locally enhanced runoff and flooding this morning. DISCUSSION...A very dynamic setup continues to unfold across the Northeast early this morning as shortwave energy and strong warm air advection lifts north out ahead of a strong deep layer trough/closed low and associated Arctic cold front over the Great Lakes and Ohio Valley. Surface observations show a low center becoming elongated across areas of eastern Pennsylvania as a warm front attempts to lift inland across southern New England as a result of the deepening and strengthening southerly flow ahead of the upstream height falls over the Great Lakes. A very impressive low-level jet is in place currently over eastern New York and central/southern New England with convergent 850 mb flow of 50 to 70+ kts overrunning this front and helping to drive enhanced Atlantic moisture transport and isentropic ascent. This coupled with strengthening divergence aloft is resulting in a fairly widespread area of heavy rain across the region with some embedded convective elements noted more recently across areas of southeast New York (including the greater New York City metropolitan area) where there is a small north/south axis of elevated instability (MUCAPE values of 100 to 250 J/kg). Over the next several hours going through late-morning, the theme across areas of far eastern New York, and especially the interior of New England will be heavy rains with a strong orographic focus involving the southeast-facing slopes of the Berkshires, Adirondacks, Green and White Mountains. In addition to this, warming temperatures in the boundary layer from the aforementioned strong southeast Atlantic fetch will be favoring a rapid melting of the pre-existing snowpack on top of locally frozen ground. The latest HRRR guidance along with the 00Z HREF members support locally an additional 2 to 2.5 inches of rain by late-morning, and this coupled with the melting snow over the terrain and relatively hydrophobic ground conditions will drive increasing concerns for enhanced runoff and flooding. Some rainfall rates especially over far eastern New York, western Connecticut, western Massachusetts, and southern Vermont may locally approach 1 inch/hour with some of these stronger convective elements outside of New York City attempting to lift north up across the interior. So, a threat for flash flooding is on the table too aside from the broader areal flooding concerns. Orrison ....Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!= DZ3fjg!98JfyZU2B8s2UsMH1C9iLer6qvfAqlYB8f2bA1zuAwQlWMFPHTlxncwhqefovFc47aNm= BDYAbYHNMGcvuVUNRB4LBqg$ for graphic product... ATTN...WFO...ALY...BGM...BOX...BTV...GYX...OKX... ATTN...RFC...MARFC...NERFC...NWC... LAT...LON 44927114 44347042 43577086 42797156 42017201=20 41397289 40847339 40787389 41107429 42267446=20 42897466 43567459 44387410 44437358 44247323=20 44457278 44297204=20 =3D =3D =3D To unsubscribe from WX-STORM and you already have a login, go to https://lists.illinois.edu and use the "Unsubscribe" link. Otherwise email Chris Novy at cnovy@cox.net and ask to be removed from WX-STORM. --- SBBSecho 3.14-Linux * Origin: capitolcityonline.net * Telnet/SSH:2022/HTTP (1:2320/105) .