Quantitative Precipitation Forecast Discussion NWS Weather Prediction Center College Park MD 257 AM EDT Sun Apr 15 2018 Prelim Day 1 QPF Discussion Valid Apr 15/1200 UTC thru Apr 16/1200 UTC Reference AWIPS Graphics under...Precip Accum - 24hr Day 1 ...Southeast into the Mid Atlantic... Convection is ongoing as of 06z across eastern MS into the FL Panhandle. This convection should maintain as it moves across the southeast today. As we head through the day instability should increase out ahead of the line...with the trough to the west also taking on more of a negative tilt with time. The combination of this increasing instability and increasing upper level divergence ahead of the trough...should allow for an intensification of the line by mid to late morning into the evening hours. In general the convective line will remain progressive in nature...likely limiting the potential for any extreme rainfall amounts. However, deep layer mean winds parallel to the line supports at least some south to north training of cells embedded within the line. Also, current convection is actually forming ahead of the true cold front, thus the potential exists for additional storms to fire on the true cold front as well...which would result in multiple rounds of locally heavy rainfall in any one location. Overall, this looks like a widespread 1-3" rainfall from the southeast into the Mid Atlantic region...with the aforementioned training and repeat cell potential allowing for localized 3-5" amounts. Would anticipate the line will remain most progressive over the southeast...with the orientation of the line likely more favorable for some training further north closer to the better mid/upper level forcing. Thus kept our highest QPF amounts from the western Carolinas northeast into portions of the Mid Atlantic. Strong southerly flow ahead of the low should help enhance rainfall totals some into the eastern slopes of the Blue Ridge and Appalachians as well. Instability will be greater across SC/NC...so certainly some chance the convective line really gets organized there this afternoon...which could limit amounts a bit further northwest over southwest VA. However, tough to get into those details much ahead of time...but something to monitor. WPC QPF leaned exclusively on the high res guidance for this warm sector convection. Most of these solutions already seemed a bit slow compared to the current radar...thus leaned more towards the quicker high res solutions. Also incorporated some of the 0z HRRR experimental, which was more robust with amounts over SC/NC than the HREF component members were. As mentioned above, given the better instability here, there is certainly a possibility that the higher amounts do verify here. ...Upper MS Valley---Great Lakes into northern NY and northern New England... A surface low will continue to slowly track east across the OH Valley today. To the north and northwest of this low will see continued wintry precipitation across MN/WI/MI. Did trend WPC QPF a bit slower, with the closed low not as progressive as previously forecast. This increases QPF amounts over portions of MN/WI. The GFS may still be a tad quick with progressing precipitation eastward, with the new 0z HREF closer in line with the 12z ECMWF and 0z UKMET. WPC QPF is thus higher than the GFS solution, and ends up pretty much in line with the HREF mean. Across northern NY into northern New England saw better consistency with QPF amounts, thus changes were generally minor here. Chenard