Area forecast discussion National Weather Service Gaylord Michigan 719 PM EDT Thursday may 23 2013 Synopsis... issued at 357 PM EDT Thursday may 23 2013 High pressure is building into northern Michigan tonight...to put the kibosh on the soggy conditions and usher in a beautiful Holiday weekend. That high pressure system will stick around through at least Monday...providing plenty of sunny but seasonably cool days and chilly nights. So chilly in fact...that frost will be possible over the next couple nights. && Update... issued at 718 PM EDT Thursday may 23 2013 Skies continue to clear from northwest to southeast across our County Warning Area this evening as strong Canadian high pressure and dry air through the column build into the western Great Lakes region. As skies clear and winds diminish with sunset...temperatures will quickly fall through the 40s and into the 30s overnight. Frost development is still a good bet given current dewpoints in the low 30s. && Short term...(this evening through friday) issued at 357 PM EDT Thursday may 23 2013 On the latest surface weather map...1033 mb high pressure was over northern Manitoba Canada with 1004 mb low pressure over northeast New York state. Apx and surrounding radars show the back edge of departing rainfall exiting into Lake Huron. Satellite imagery and surface observations shows marked clearing advecting in from the north and west. The main short term forecast concern revolves around low temperatures and associated frost/freeze headlines tonight. Tonight...unseasonably cold air associated with Arctic type high pressure continues to build in from the northwest. This will result in slowly diminishing winds and mainly clear skies. There are a couple of competing factors to contend with as far as low temperatures go. Boundary layer winds do not look like they fully decouple with 950 mb winds remaining in the 15 to 20 knot range through 12z Friday. However...from a pure cold advection standpoint with 850 mb temperatures bottoming out between -2 and -3 c...temperatures should not have much of a problem falling through the 30s. Could even see some sheltered spots hit the upper (or even middle 20s). So at a minimum...temperatures expected to be cold enough to support frost (though the extremely dry air mass void of much moisture in itself may not produce much actual frost) in addition...temperatures in a few sheltered spots could support a freeze (but this is not expected to be widespread). So with all this in mind...will continue with the ongoing frost advisory...as well as an expansion eastward into the remaining counties bordering Lake Huron. Friday...high pressure continues to build in from the northwest with a very slow modification in temperatures. Model sounding/cross sections are very dry...supporting little to no cloud cover...so mostly sunny conditions are expected. Temperatures are still expected to be a good 10 to 15 degrees below average for late may with highs only in the middle 50s to around 60. Long term...(friday night through thursday) issued at 357 PM EDT Thursday may 23 2013 Recent trends: temperatures...warming trend last seven days across northern Michigan (about 2-4c above average) though not a great start out there today. 1-3c above normal for the month of may thus far. Precipitation/hydrology: significant rainfall last couple of days...some locales picking up 2-3+ inches of precipitation. Overall soil moisture (top 1m) still above normal...top 25cm mostly below 50 percent capacity. Area rivers on the rise after rainfall...Rifle river near Sterling already in flood with a forecast rise of another 1.5 feet or so. Great lakes: water temperatures averaging 4-5c northern lakes Michigan/Huron...around 6-7c from Beaver Island north and east to The Straits. Lake Superior/Whitefish Bay around 3c. Large scale pattern/forecast: small-scale Omega blocking pattern across North America with troughs east and west and a narrow ridge in between. Overall recent pattern has been pretty progressive (45 day hovmoller analysis reflects this rather nicely)...though the current blocking will keep things hemmed in a bit with East Coast cyclogenesis this weekend helping bog things down. But the overall trend into next week should be rising heights across the east with more persistent troughing out west (and thus an overall warming trend). High pressure builds into the Great Lakes this weekend and gets stuck between aforementioned East Coast cyclone and Lee cyclogenesis across the Central High plains. Water vapor imagery shows a compact vorticity center crossing 60n into northern Manitoba this afternoon that is forecast to fly by east of Michigan early Saturday...but otherwise not much expected synoptically through Sunday. Main forecast concerns look to revolve around temperatures and frost potential this weekend. Friday night through sunday: short wave trough/jet streak will drop across Lake Huron from the northwest Friday night...disturbance does have an area of cirrus with it that will float across for a time. Will probably have some impact on low temperatures but still expect a chilly night with lows dropping into the 30s with some threat for frost across the interior. Partly to mostly sunny Saturday...deep mixing will allow temperatures to warm into the 60s though may still fall a bit short of average for the day. Similar story on tap for Saturday night...clear/clearing skies and light/calm winds with surface ridge stuck in place. Plan to mention frost potential Sunday morning with lows across the interior in the Lower-Middle 30s. Plenty of sun expected Sunday afternoon along with seasonable temperatures. Extended forecast (monday through thursday): high pressure expected to hold on into the Memorial Day Holiday and likely into Tuesday as well. There will be a warm front across the Central Plains and into the middle Mississippi Valley that will be the main focus for precipitation into next week...how quickly this feature lifts north toward the Great Lakes will be the issue for the latter half of the extended periods. Temperatures will moderate Monday/Tuesday...but will start getting into better warm advection by midweek. May also start to get noticeably more humid...and by Wednesday may be enough instability in place for some shower/thunderstorm development. Better chances for precipitation may be in the offing for Thursday as warm front nudges closer. Highs Memorial Day should be well into the 60s/lower 70s...with more 70s during the midweek period. && Aviation...(for the 00z tafs through 00z Friday evening) issued at 718 PM EDT Thursday may 23 2013 Mainly sky clear is expected at all taf sites through Friday evening as strong Canadian high pressure and dry air through the column build south into Michigan. Gusty north winds will diminish with sunset this evening...and then become gusty again on Friday. && Marine... issued at 357 PM EDT Thursday may 23 2013 Gusty north winds through this evening due to a tight surface pressure gradient and strong winds aloft. Winds are then expected to slowly diminish overnight as high pressure begins to build into the nearshore waters. Therefore...have extended the small craft advisories through late evening. High pressure is then expected to gain full control Friday into the Holiday weekend leading to headline free conditions. && Apx watches/warnings/advisories... Michigan...frost advisory from 2 am to 8 am EDT Friday for miz016>036-041- 042. LH...Small Craft Advisory until 10 PM EDT this evening for lhz345>349. Lm...Small Craft Advisory until 10 PM EDT this evening for lmz323-341- 342-344>346. Ls...Small Craft Advisory until 10 PM EDT this evening for lsz321-322. && $$ Update...mr synopsis...kab short term...ajs long term...jpb aviation...mr marine...ajs