Subj : MESO: Nws Weather Prediction Center College Park Md To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Fri Apr 12 2024 12:48:37 AWUS01 KWNH 121248 FFGMPD MEZ000-MAZ000-NHZ000-121845- Mesoscale Precipitation Discussion 0155 NWS Weather Prediction Center College Park MD 846 AM EDT Fri Apr 12 2024 Areas affected...Northern New New England Concerning...Heavy rainfall...Flash flooding likely Valid 121245Z - 121845Z SUMMARY...Heavy showers over the next several hours combined with snowmelt over the higher terrain is likely to result in areas of flash flooding going through early this afternoon. DISCUSSION...A deep layer trough of low pressure continues to advance into the Northeast U.S. this morning with a surge of strong warm air advection and moisture transport lifting up across much of New England. In fact, A warm front continues to surge northward across the interior of New England which is yielding the arrival of a notably warm/moist airmass in off the western Atlantic Ocean. The early morning CIRA-ALPW data shows the LPW in the SFC/700mb layer exceeding the 95th percentile of climatology, and this will play a key role in conjunction with a southerly low-level jet of 50 to 60+ kts in driving efficient rainfall processes for elevated rainfall rates. The CIRA-LVT magnitudes below 700 mb are particularly strong right now nosing up across areas of central/eastern MA and southern NH, with magnitudes exceeding 300 kg/m/s. Radar imagery shows a batch of heavy shower activity including a few thunderstorms riding northward across eastern MA and RI which will likely get up into areas of central/southern NH and especially southwest ME over the next few hours. A nose of instability is associated with this area of convection with MUCAPE values of as much as 500 to 1000 J/kg, and this coupled with the efficient moisture column is driving rainfall rates of as much as 1"/hour with the stronger convective cells, although much of this rainfall is tending to fall in as little as 30 to 45 minutes in some cases. Overall, the latest hires model guidance including the HRRR and overnight HREF members appear to be a bit underdone with the ongoing areas of heavy rain. The expectation is that rainfall rates and coverage of heavy rain may increase going through midday, and especially for areas of western and southwest ME. An additional 2 to 3 inches of rain may occur locally, and especially if some of the convective bands of eastern MA begins to locally train over the same area into portions of western ME. Snowmelt is a major concern at least locally up across the White Mountains this morning in central and northern NH, and adjacent areas of western ME with very warm air and high dewpoints overrunning the remaining snowpack. Aside from this, the region in general is quite sensitive with very moist/wet soil conditions. Therefore, collectively, the arrival of additional heavy rainfall over northern New England will encourage notable concerns for runoff problems and flash flooding. Orrison ....Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!= DZ3fjg!9ypj7Dzp3Kzrhu6sXJEVg5Q3MVLDphJdgvIzn5IKoowV_shxI5AbLddw_U_scTpyotAN= -3hKPursXTpMlgCDjarRieg$ for graphic product... ATTN...WFO...BOX...CAR...GYX... ATTN...RFC...NERFC...NWC... LAT...LON 45626963 45446879 44726860 44166908 43597018=20 42807104 42857174 43387198 44007195 44767124=20 45347058=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 3.20-Linux * Origin: capitolcityonline.net * Telnet/SSH:2022/HTTP (1:2320/105) .