Subj : MESO: Nws Weather Prediction Center College Park Md To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Tue Aug 08 2023 12:26:18 AWUS01 KWNH 081226 FFGMPD MEZ000-MAZ000-NHZ000-RIZ000-CTZ000-NYZ000-081824- Mesoscale Precipitation Discussion 0890 NWS Weather Prediction Center College Park MD 825 AM EDT Tue Aug 08 2023 Areas affected...Portions of New England Concerning...Heavy rainfall...Flash flooding possible Valid 081224Z - 081824Z SUMMARY...Repeating rounds of heavy shower activity are expected to drive a threat for some instances of flash flooding going through the early afternoon hours. DISCUSSION...A rather strong upper-level trough is lifting up across the St. Lawrence River Valley early this morning which is driving rather strong warm air advection up across New England and is facilitating the poleward advance of tropical moisture up along the East Coast and in off the Atlantic Ocean. This coupled with a nose of at least modest instability with MUCAPE values of 500 to 750 J/kg will be driving multiple rounds of heavy shower activity going through the morning hours, and the latest radar imagery does show a broken axis of heavy showers stretching from portions of eastern CT and eastern MA up through eastern NH and into large areas of central and southern ME. PWs across the region are anomalously high with values of 1.75 to 2 inches, and there are some suggestions in GOES-E IR satellite imagery of warm-topped convection producing highly efficient and heavy rainfall rates. Some of these rates are locally as high as 1 to 1.5 inches/hour. There are some concerning signals coming out of the last several runs of the HRRR guidance which suggest a well-defined axis of repeating/training convection across areas of central and southern ME going through the midday hours, with enhanced rainfall rates that may increase to as much as 2 inches/hour. Driving this threat will be somewhat stronger forcing arriving across the region in association with left-exit region upper-jet dynamics around the southeast flank of the upper trough. A strong low-level jet is also forecast to be reaching as high as 40 to 50 kts out of the southeast which will maintain strong Atlantic moisture transport and will be aiding stronger low-level convergence and orographic ascent. The remaining HREF solutions from the 06Z cycle are generally not as aggressive as the recent HRRR runs, but nevertheless are supportive of locally organized heavy rainfall potential going through the late morning and early afternoon hours. The environment should be conducive for seeing repeating and/or training bands of convection, and based on this, rainfall totals of as much as 3 to 4 inches may be possible going through the early afternoon hours. The heaviest rainfall should tend to be over central and southern ME, but adjacent areas of New England will also be seeing locally a couple inches of rainfall potential. Areas of flash flooding will be possible by later this morning and early this afternoon as these heavier rainfall totals materialize. Orrison ....Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!= DZ3fjg!7rOAChXOndqPfRJY1sbpReyK9fOnF-Oi01OPDOas3m6P1TyakWdZNSPSukj4bkZFMW1e= ZWQS3yAswPCYyAcXGR5mx3U$ for graphic product... ATTN...WFO...BOX...CAR...GYX...OKX... ATTN...RFC...NERFC...NWC... LAT...LON 47506928 47486808 46896767 45976793 44916851=20 43896927 43137013 42027083 40967185 40917239=20 41267248 41897212 43617148 45527074 46727015=20 =20=20=20=20=20=20=20=20=20=20=20=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) .