Area forecast discussion National Weather Service Pocatello Idaho 658 PM MDT Thursday may 23 2013 Update...updated grids for light precipitation and gusty winds for this evening as a weak trough moves through eastern Magic Valley and the Snake River Plain. The leading edge of the trough has just passed through Pocatello and is creating gusty winds of 25 to 35 miles per hour through the eastern Magic Valley and the Snake River Plain. Visibilities are slightly reduced with isolated pockets of blowing dust. Wyatt && Previous discussion... /issued 124 PM MDT Thursday may 23 2013/ Short term...tonight through Sunday. The deep upper low continues to spin over Washington this afternoon. A secondary circulation center near the northern California/Nevada border is expected to rotate into Idaho by this evening. This wave will set off scattered showers and isolated thunderstorms over the northern part of the forecast area this afternoon and evening before rotating into Montana later tonight. The upper low is expected to lift out of Washington into British Columbia/ab on Friday. This will take most of the precipitation north out of the area...with only isolated showers in the far north through Friday night. Precipitation coverage will increase somewhat over the central mountains Sat afternoon/evening as another minor upper wave moves through. A more vigorous upper trough moves into the Pacific northwest on Sunday. This will increase the threat of showers and isolated thunderstorms across the forecast area Sun afternoon...with the best chances in the north. The cold upper low today...along with clear skies and light winds will allow temperatures to fall to unseasonably cold readings Friday morning. Temperatures will be very near 32 f in outlying areas...so a frost advisory will be issued for the Snake River Plain/eastern Magic Valley. Temperatures will warm up for Friday afternoon and through the weekend. Hedges Long term...Sunday night through Thursday. Overall models differ in this period in strength and timing of troughs moving through eastern Idaho but both European and GFS models indicate convective activity Monday through Wednesday at least. Kept in slight chance or chance of showers and thunderstorms in each period. Will be many dry periods but with the model and timing differences tough to distinguish. GFS keeps upper low off coast while European more progressive and zonal in flow aloft. Temperatures should be near seasonal normals within a few degrees. Gk Aviation...has been VFR today with mainly a middle level cloud deck. Expect isolated showers and thunderstorms near sun and have that as vicinity in taf. At 1 PM up valley winds have not yet developed at pih and Ida but expect some mainly 10 to 15 knots at most later this afternoon. Continued VFR through Friday. Gk && Pih watches/warnings/advisories... frost advisory from 3 am to 8 am MDT Friday idz017-020-021. && $$