Area forecast discussion National Weather Service Buffalo New York 225 PM EDT Wednesday Jun 19 2013 Synopsis... a broad area of high pressure over the central Great Lakes will settle over the region tonight...and remain over the northeast through Friday. This area of high pressure will bring fair weather...cool night...and comfortable levels of humidity. As the high slides off the East Coast this weekend...a southwesterly return flow of warmer and more humid air will develop across the region. && Near term /through Thursday/... a continued beautiful afternoon as high pressure over the central Great Lakes pushes towards our region. There are comfortable levels of humidity with temperatures...a tad below normal...but still in the middle to upper 60s across much of the region. Like last night it will turn cool quickly this evening as ideal radiational cooling conditions persist. Clear skies will allow temperatures to quickly cool into the 50s this evening...and dropping back into the 40s overnight. A few spots in the valleys of the southern tier...and north country may dip into the upper 30s. Like last night some River Valley fog may form through the southern tier and into the valleys of Wyoming and southern Livingston County. With the dewpoint depression about the same as last night...will insert patchy River Valley fog into the grids. This area of high pressure will begin to slip to the eastern Seaboard Thursday. Aloft building 500 hpa heights...and 850 hpa temperatures warming to about +10 to +12c will promote a warmer day Thursday. Highs will climb into the 70s across much of the region...which is much closer to normal. Though the humidity will rise some also...dew points will remain around 50f or lower...which is still comfortable. Again will see some afternoon clouds forming through the southern tier with the daytime instability. Expect the greatest number of fair weather cumulus over the hills of the interior southern tier where 850-500 hpa layer moisture is deepest. && Short term /Thursday night through Saturday night/... multi model and ensemble consensus continues to build middle and upper level ridge axis across the lower lakes region for much of the period...before shifting it eastward in association with the ejection of a significant northern rockies shortwave trough into northern Great Lakes by Saturday. Certainly looks like a precipitation free period in the Thursday night through at least Friday night time frame with warm middle level temperatures underneath upper ridge. Weak low level flow should limit the northern extend of the Theta-E advection and result in effective middle level capping inversion through this period. Saturday...we continued the low end probability for convection during the afternoon as the upstream sharp middle level trough makes its eastward progression and some inherent breakdown of the middle level ridge takes place. Better return flow brings more low level moisture northward with lake breeze convergence areas the most likely trigger for any afternoon convection. Gradually warming through the period with highs in the upper 70s to lower 80s on Friday and into the lower to middle 80s by Saturday. && Long term /Sunday through Wednesday/... some degree of differences arise in the model guidance between the GFS/European model (ecmwf) regarding the potential for showers and thunderstorms development during this period. Now for the details...latest 12z GFS guidance package suggests that the lower Great Lakes will be on the northwestern edge of an expansive ridge of high pressure building into southern Continental U.S.. return flow around this ridge of high pressure will pump an ever increasing warm and moist airmass into the region. This will keep the potential for a chance of daily showers and thunderstorms in the forecast. The European model (ecmwf) shows a broad but Flat Ridge of high pressure over the southern Continental U.S. With zonal flow over the Great Lakes region. Several weak shortwaves embedded within this flow will bring a chance for showers/thunderstorms across the region with brief lull between shortwaves. However...one thing is for sure both models show that the first full week of Summer will exhibit to some degree warmer than normal temperatures. Medium range MOS guidance and wpc show maximum temperatures ranging between 82f-87f across most of interior sections of western and north central New York during this period. && Aviation /19z Wednesday through Monday/... at 18z VFR flight conditions were found across the region...and these flight conditions should prevail for the remainder of the taf period. Like last night...some valley fog in the southern tier may develop overnight...but it will likely remain shallow and not impact the kjhw airfield. Winds will remain light...and variable as the area of high pressure settles over the region. Outlook... Thursday and Friday...VFR. Saturday through Monday...VFR with a chance of showers and thunderstorms. && Marine... a broad area of high pressure over the central Great Lakes will build towards western New York by Thursday morning...then will gradually settle to the East Coast Thursday and Friday. This feature will bring fair weather today through Friday...along with light winds and negligible waves. && Buf watches/warnings/advisories... New York...none. Marine...none. && $$ Synopsis...Thomas near term...Thomas short term...tma long term...Arkansas aviation...Thomas marine...Thomas