Quantitative Precipitation Forecast Discussion NWS Weather Prediction Center College Park MD 259 PM EDT Sun May 27 2018 Prelim Day 1 QPF Discussion Valid May 28/0000 UTC thru May 29/0000 UTC Reference AWIPS Graphics under...Precip Accum - 24hr Day 1 ...Southeast / Alberto... The forecast track for Alberto trended east and a little slower at 15Z compared to 09Z, though in terms of the track, the east shift that was observed in the past few model cycles has ended. The core of the system will track up through the eastern Gulf today, then is forecasted per the latest NHC advisory near Panama City by 12Z Monday. Generally difluent upper flow and deep layer ascent will support generous rainfall coverage over much of Florida / drying out a bit over southwest Florida. The conveyor belt out to the east of the parent synoptic trough may set up convergence right over southeast Florida. Much of the guidance is not especially well focused in the QPF fields, but the pattern is a little concerning as cells dropping tropical style rainfall could train over the urban areas / Miami. Some models are just offshore to the east with the heaviest...but based on the NAM mass fields we painted healthy areal average rainfall over Miami and more generally the southeast coast of Florida to the tune of 2-3 inches. Expect embedded heavier amounts. Meanwhile the difluent region farther north and east will migrate up through southeast Georgia and into the Carolinas with time. Expect again heavy areal average rainfall and embedded totals exceeding 3 inches through Monday morning. WPC QPF was initially derived from the multi-model ensemble, and continuity, then later trended toward the consensus of the more recent HRRR/experimental HRRR runs through the Sunday night period. ...Mid Atlantic... A shortwave trough had ignited a well of instability pooled along a warm front in New Jersey, resulting in flash flooding early this morning. Other scattered activity was ongoing in the moist plume over Virginia to southern Maryland. In the wake of this wave, convergent 850-700-mb flow is forecast to set up during peak heating from central Virginia to southern Maryland. The hi-res models, on average, light up this axis with organized afternoon thunderstorms and locally heavy rainfall. The global models, however - ECMWF and GEFS ensemble 6-hour probabilities - have shown a slight trend to the north which could place more heavy rain into the Washington D.C. vicinity. WPC QPF was centered toward the HREF mean and ECMWF. ...Western/Northern U.S... There will be another round of widely scattered diurnal convection to the rear of the upper trough where low level moisture and mid level lapse rates are sufficient. Farther east height falls and upper difluence will overspread the high plains, and despite warm mid level temperatures it does appear the low level moisture will improve to the extent needed to support clusters of thunderstorms from MT/WY down through western KS and into the OK/TX panhandles. An early morning MCS will also drift downstream through ND/MN...with additional afternoon activity expected to form there along a front. All these things in the west and north were best described by the WRF-ARW2 and HREF Mean, blended with WPC continuity. Hurley/Burke