Area forecast discussion National Weather Service Goodland Kansas 523 PM MDT Sat may 25 2013 Short term...(this evening through sunday) issued at 212 PM MDT Sat may 25 2013 Upper flow will be southwest through Sunday. Surface low pressure will be over eastern Colorado through the period. A weak shortwave comes through the flow this evening into the forecast area and a second stronger one on Sunday. There is plenty of cape (2000-3000 j/kg) available for storms this evening and 2500 to 3500 j/kg Sunday. Expect storms to fire in eastern Colorado near the dryline and surface trough. Forecast soundings indicate high based storms with little precipitation reaching the surface. For this reason plan on going with slight chance and chance probability of precipitation for tonight. Storms will fire near the warm front Sunday afternoon which will favor higher probability of precipitation in the northeast half of the forecast area. Once again storms will be high based so will lean toward slight chance and low chance probability of precipitation. Boundary layer relative humidity increases above 90 percent in the far eastern forecast area early Sunday morning. Relative humidity decreases after 15z so will include some stratus and patchy fog. 850 temperatures around 30c Sunday will support temperatures rising to the middle 90s in the south and around 90 in the north and east. Min temperatures tonight will cool to the middle 50s to the lower 60s east. Long term...(sunday night through saturday) issued at 245 PM MDT Sat may 25 2013 Chances for showers and thunderstorms continue to be the main focus of the forecast. A few changes in the model data have prompted some slight changes to portions of the extended forecast. These changes will be discussed below. Showers and thunderstorms should again develop along a dry line ahead of the Lee low pressure and continue into the overnight hours tomorrow night. Some of these storms will be strong to severe as mentioned in the short term discussion. Most of the activity will diminish by midnight but some precipitation could continue past midnight due to boundary interactions as was observed around Hill City and Norton Kansas last night. Warm low temperatures are again expected with lows only falling into the upper 50s to middle 60s. Variable winds are forecast as the surface low moves across the tri-state area. On Monday...chances for precipitation continue to look lower than previous and upcoming days. The best chances will generally be over the northeast half of the area ahead of the dryline. Storms could be strong to severe again with surface cape values of 2000 j/kg...0-6km bulk shear of 35 to 45 kts and favorable lapse rates of 8 to 9 c/km. The main threats will be damaging wind and large hail as low level moisture looks somewhat low for a low tornado risk to be mentioned. One of the bigger changes to the extended forecast was to increase the chances for showers and thunderstorms during the day on Tuesday. A large upper level trough of low pressure will begin to have an influence on our weather starting on Tuesday. This is somewhat faster than previous model runs and the GFS...Canadian...European and NAM models all show the chance for precipitation. This is due to models expecting an earlier initial shortwave to pivot around the trough as well as a dryline farther to the west that previous runs. Have increased probability of precipitation into the chance category but if models continue to show a consistent solution...chances for precipitation will need to be increased again. The main days for precipitation with this upper level trough and associated shortwaves swinging around the edge will be on Wednesday and Thursday. Several rounds of showers and thunderstorms should develop ahead of a surface low pressure to the west and a dryline bisecting the forecast area. Some storms will again be strong to severe...however instability for this system looks somewhat less than previous forecast runs. This could be reflecting a convective feedback mechanism within the models as more widespread and possibly heavier precipitation is forecast. The shear looks better for this event as stronger winds aloft should move through in association with this trough of low pressure. This looks like the best chance for some heavier...soaking...much needed rainfall that this area desperately needs. Temperatures throughout the forecast period will remain above normal for this time of year. A cold front will cool things off towards the end of next week with near normal temperatures forecast. && Aviation...(for the 00z tafs through 00z Sunday evening) issued at 523 PM MDT Sat may 25 2013 Primary aviation concern early in the taf period will be thunderstorms that have already developed around the kgld terminal...with additional activity moving into the kmck terminal within the next hour. These storms do have a history of producing large hail...however from this point forward confidence in occurrence at the terminals is too low to include hail mention in taf. Most activity should transition to the north and east through the evening possibly lingering at kmck through the overnight. VFR conditions should prevail at kgld through the taf period with fog/stratus developing by sunrise at kmck. Currently expecting MVFR conditions after 09z transitioning to IFR by 12z. There is some indication of lower conditions...however this could be dependent on overnight precipitation clearing. && Gld watches/warnings/advisories... Kansas...none. Colorado...none. NE...none. && $$ Short term...fs long term...rrh aviation...Dr