Very rainy weekend ahead; North Central Nebraska could see 3+ inches

OMAHA/VALLEY -- Forecasters at the National Weather Service in Omaha/Valley are predicting a very slow storm system could bring 3-plus inches of rain to portions of north central Nebraska. Most areas will see just over 1.5 inches as the cold front begins on Saturday night and works its way through Nebraska next Tuesday. Rain in southeast Nebraska will most likely hold off until Sunday night. None of the slow moving storms are expected to be severe. Here's the actual Long Term (Sunday through Tuesday) Forecast from the National Weather Service: From Saturday night through Monday, the surface front and forcing aloft will make a very slow progression across the forecast area. In fact, the surface cold front is unlikely to push all the way through the forecast area until late on Tuesday. This slow progression is largely due to the slow eastward motion of the long-wave trough which maintains deep front-parallel flow in the mid and upper levels. The general frontal zone is also likely to remain in the vicinity of a steady stream of short wave troughs moving through the fast flow aloft. These individual waves, with their enhanced convergence, ascent, and cooling aloft, will support periods of enhanced precipitation coverage and rates. Precipitable water values will frequently be in the 1.5-1.8 range which is quite high for this time of year, and the warm cloud depth and freezing levels are climatologically quite high as well. This, along with the rather long duration of the event and presence of modest deep instability through much of the period suggest that heavy rainfall will be likely in parts of the area. Exact amounts will depend highly on periods of convective enhancement and training, but the most favored area for heavy rain is likely to be focused in north central Nebraska where some locations will likely receive more than 3 inches and possibly a fair amount more. Farther southeast, the majority of rain in far southeast NE and southwest IA may hold off until Sunday night or Monday while north central NE will likely experience off-and-on thunderstorms for a majority of the period Saturday into Monday. All told, severe storm potential is quite low. There are a few periods for which the instability/shear combination may be sufficient to support storm organization, but more frequently expect heavy rain to be the primary focus through this event. Late Tuesday through the remainder of the week looks to be predominantly dry with a return to split flow aloft and near-normal temperatures.