Warmer Weather Arrives, but Isn’t Ready to Dig in Its HeelsMay 5th, 2014 at 9:44 pm by Don Paul under 4 Warn Weather
The warmup we advertised all last week for later this week is still on the way, along with some Scattered convection at times. So, the “big picture” hasn’t changed much. As for details, the approach of a warm front midweek will probably set off some weak convection by late Wednesday, picking up at times Wednesday night into portions of Thursday. The proximity of this front and some elevated instability (bubbly air aloft out ahead of the warm front) will probably fuel a few of these tshowers. In fact, by Thursday afternoon and evening, our surface airmass will take on an “Almost Muggy” feel, with daytime highs in the 70s and overnight lows from the upper 50s to near 60–accompanied by higher dewpoints. The timing for actual warm frontal passage is still in question on this (Monday) evening. Once we get into the warm sector and that boundary has passed to the N & E of us, activity will slacken. As we move into Saturday, a wave or 2 will move up along a cool front and bring us a few rounds of showers & possible tshowers Friday night into portions of Saturday. There are signs much of this moisture will pull off to the east Saturday evening. On Sunday, the Canadian GEM is an outlier with a short wave bringing a return of showers for part of the day. But both the GFS and ECMWF seem to keep us mainly dry and seasonably mild Sunday. Monday becomes more of a question mark. The ECMWF rebuilds a strong ridge in the east, which blocks the approach of a cold front and its convection until Wednesday PM-Thursday, while the GFS brings some convection back to WNY as early as Tuesday or even later Monday night. Right now I’m leaning toward the ECMWF and its ensemble mean, but confidence remains shaky at best (both periods in the CPC outlook are of Below Average confidence — 2 out of 5), so I know I’m not alone in eyeing this model and ensemble disarray warily.
The ensemble means do bring some troughing back closer to the east central or eastern US between the 14th & the 16th, which would drop temps back below average for a few days. The ECMWF mean flattens the flow later in the period, while the GFS takes longer to show a zonal flow. Again, the zonal depiction late in the period may possibly be tied to the smoothing of the wide spread between ensemble members, rather than a realistic representation of a zonal flow. That idea doesn’t necessarily mean the troughing will persist. The ensemble member spread could also hide some modest return to western troughing and eastern ridging…too early to tell.