Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 03/20/17


Area Forecast Discussion
National Weather Service Gaylord MI
1148 PM EDT Sun Mar 19 2017 .UPDATE... Issued at 1003 PM EDT Sun Mar 19 2017 A bit of interesting weather out there this evening, as subtle shortwave works in tandem with corridor of robust mid level lapse rates and just enough elevated moisture to kick off a band of showers and a few thunderstorms across the northern Lakes. This area of showers is steadily moving east, and starting to get some hints of intensification over Lake Michigan as it merges with low level jet riding atop the lakes cold dome. However, nothing significant for sure as low level dry air has really done a number on precipitation amounts reaching the surface. Expect this trend to continue for a few more hours, although loss of lake induced jet and a relaxation of mid level lapse rates should gradually end the thunder threat and cause a much more scattered appearance to shower activity through the night. Have had some upstream reports of mixed precipitation with initial surge of evaporational cooling, although this has been very brief in nature. Expect the same for our area, with perhaps the precip starting off as snow or even a touch of light freezing rain, especially across eastern upper Michigan. Once again, not expecting any significant impacts given light amounts and short duration of wintry mix. Of course, would still use some caution when traveling those secondary and untreated road surfaces. && .NEAR TERM...(Tonight through Monday) Issued at 337 PM EDT Sun Mar 19 2017 ...Mild with light showers possible tonight into Monday... High Impact Weather Potential...Minimal. Could be a few rumbles of thunder along Lake Michigan overnight. Pattern Synopsis/Forecast...Positively tilted upper level ridge axis will continue to slide across Michigan heading into this evening. At the surface, a sprawling high sitting over the area will push east of Michigan by this evening. This has led to mostly sunny skies across the much of the forecast area today, though mid/upper level clouds are starting to increase. Temperature advection pattern has been holding neutral today while we`ve been under the high, but once it pushes east tonight we`ll enter a period of moderate to strong WAA that will continue into Monday. A surface trough/weak cold front will approach the area late this evening, but it will encounter a very dry layer just above the boundary layer. Without much low level moisture advection, this moisture-starved system (surface dewpoints in the upper 20s to lower 30s) is will struggle to squeeze out much precipitation over northern Michigan overnight. Models have also been trending towards less QPF with this system, especially as it moves east across the APX forecast area. Have therefore only gone with low end chance to slight chance PoPs tonight. The 19.12Z suite of deterministic models have all picked up on some possible weak shortwave enhancement beginning around midday on Monday, mainly affecting northern Lower south of M-32. So have continued slight chance PoPs through the day Monday, focusing more across our southern counties in the afternoon. Winds turning NW behind the surface trough will quickly usher in a drier airmass Monday afternoon that will lead to clearing skies. Under the strong WAA developing tonight, temperatures will likely experience a slight bump or at least hold nearly steady beginning around midnight, then rapidly rise through the 40s Monday morning. Highs will be in the low 40s across eastern Upper, ranging from the mid 40s to low 50s across northern Lower. Primary Forecast Concerns...A few rumbles of thunder will not be out of the question late this evening, mainly along the Lake Michigan shoreline south of the Leelanau Peninsula. Despite limited low level moisture in place, PWATs will be around 3/4 of an inch there. This will result in some elevated instability (generally above 700mb). Not sold on forcing being strong enough to lift a parcel from that level, though, so have not included thunder in the forecast. Recent HRRR runs have shown some interesting 1 km AGL reflectivity patterns, though, developing some weak cellular activity over Lake Michigan. Other concern for tonight is the potential for some frozen precip before the main push of WAA arrives. Depending on how fast temperatures drop this evening, some locations over eastern Upper may dip down to freezing as the precip arrives. Wouldn`t rule out a bit of spotty freezing rain up there, but certainly nothing that would be impactful. With evaporative cooling, there could be some flakes mixing in with the rain early on across forecast area, but the arrival of warmer temperatures would lend itself to primarily rain after midnight. && .SHORT TERM...(Monday night through Wednesday) Issued at 337 PM EDT Sun Mar 19 2017 ...Turning colder starting Tuesday afternoon... High Impact Weather Potential: Minimal. Pattern Forecast: Short range period starts in the wake of a cold front that will cross Michigan during the day Monday...as the Great Lakes lies along the southern gradient of a broad trough over Manitoba/Ontario/Quebec with a couple of embedded short wave troughs moving through the base of this trough. One such short wave trough/ jet streak will cross northern Michigan Tuesday...and drag a secondary cold front across the area as a near 1040mb Arctic high builds southeast into Manitoba/Ontario. This high will eventually settle across the upper Great Lakes during the midweek period (surface pressure over Michigan around +2 standard deviations for mid March). Primary Forecast Concerns: As mentioned above...short wave trough/jet streak will be moving across northern Michigan Monday night/Tuesday morning...with resultant height falls bringing a second cold front (and more substantial push of colder air) into the forecast area during the day Tuesday. In response...expecting an increasing lake response as Tuesday wears on and cold advection strengthens. This will initially occur over Lake Superior (along with a diurnal component) with some clouds and perhaps some light snow showers/flurries...then spread into northern portions of Lakes Michigan/Huron with boundary layer flow having a substantial northerly component. Tuesday temperatures should fall during the afternoon across the eastern U.P...while expecting highs across most of northern Lower to climb into the lower-mid 40s as next shot of cold air not expected to arrive until closer to evening. Coldest air will have settled across the region Wednesday morning with 850mb temperatures in the -15C to -20C range...though will moderate during the day...while Arctic high builds into Michigan. Could be some lingering lake induced stratocumulus around...but for the most part looks like a dry day with a fair bit of sunshine. But it will be chilly by mid March standards with highs in the upper 20s- lower 30s expected. .LONG TERM...(Wednesday night through Sunday) Issued at 337 PM EDT Sun Mar 19 2017 High Impact Weather Potential...Minor, but with a potential for a wintry mix increasing Friday night. At upper levels, a deep 500mb trough which dropped into the Great Lakes earlier in the week, will exit east on Thursday while upper ridging builds across the Great Lakes for the weekend. Mid level temperatures will warm drastically across the region in response to the building upper ridge, with 850mb temps of -10c early Thursday warming to between +4c and +6c Friday and the weekend. This will generate seasonal afternoon temperatures in the 40s across northern Michigan through the period, maybe nearing 50 degrees Friday. At the surface, a central Plains storm system will quickly lift across the Great Lakes Friday while a large area of high pressure settles into the Great Lakes for the weekend. Overall will continue with a dry forecast through Thursday afternoon, with some wintry mix possible into Saturday morning, followed by some sun and mild temperatures for the weekend. && .AVIATION...(For the 06Z TAFS through 06Z Monday night) Issued at 1146 PM EDT Sun Mar 19 2017 Band of scattered relatively high based showers expected to move across the area early this morning. MVFR producing cigs are possible following these showers this morning. Will need to be on the lookout for additional shower development today as a cold front sweep through the region. Mostly light winds expected through the period. && .MARINE... Issued at 357 PM EDT Sun Mar 19 2017 Southerly winds will increase tonight behind a departing high pressure system. Late this evening and through early Monday morning, borderline small craft advisory wind gusts will be possible over the Lake Michigan nearshore waters, south of the Leelanau Peninsula. A weak cold front will sweep through the region Monday morning, causing winds to veer to the NW through the day. Stronger winds develop over Lake Superior and Whitefish Bay Tuesday morning with more widespread SCA winds arriving during the afternoon across the Upper Great Lakes. && .APX WATCHES/WARNINGS/ADVISORIES... MI...NONE. LH...NONE. LM...NONE. LS...NONE. && $$ UPDATE...MSB NEAR TERM...MEK SHORT TERM...JPB LONG TERM...SWR AVIATION...MSB MARINE...MEK
Area Forecast Discussion
National Weather Service Charleston SC
956 PM EDT Sun Mar 19 2017 ...FROST ADVISORY ISSUED FOR PORTIONS OF INTERIOR SOUTHEAST SOUTH CAROLINA... .SYNOPSIS... High pressure will build across the area through Tuesday. A cold front will drop south through the area Wednesday as a wedge of high pressure builds in from the north. The high will shift off the coast Friday into Saturday. A storm system may affect the area next Sunday. && .NEAR TERM /UNTIL 6 AM MONDAY MORNING/... The boundary layer has quickly decoupled this evening and winds have gone calm for all but the coastal corridor. Coastal winds should subside over the next few hours as high pressure builds south. Temperatures have fallen off quickly since sunset with lower-mid 40s already being reported in the Walterboro-Huger corridor as of 20/01z. High resolution guidance continues to show much of interior Southeast South Carolina dropping into the mid 30s prior to sunrise with dewpoints recovering to the lower-mid 30s. This will support scattered frost early Monday, especially along/north of an Allendale-Crocketville-Hendersonville- Ravenel-Awendaw Line, but away from the Santee-Cooper lakes and the I-26/I-526 areas in Charleston County. A Frost Advisory has been issued for these areas from 4-8 am Monday. It should be noted that both the H3R and RAP show some areas dropping to 31-32 degrees for 1-2 hours for the past several runs, but confidence in this is not high enough to warrant a Freeze Warning at this time. Opted to lower overnight lows another degree or so for some areas, but keeping temperatures above freezing. The rest of the forecast is on track. && .SHORT TERM /6 AM MONDAY MORNING THROUGH WEDNESDAY/... Surface high pressure will slide over the area and then into the Atlantic on Monday allowing for a sunny and pleasant day. A backdoor cold front will slowly approach from the north Tuesday. Warm advection and downslope flow will boost temperatures several degrees above normal. Highs are expected to peak in the low to mid 80s across most locations inland of the beaches. Any precipitation should mainly stay to the north through the day, however maintained slight chances in the extreme northern portions of the forecast area. The cold front is progged to drop through the forecast area on Wednesday. Shortwave energy and some increase in moisture will allow for a chance of showers. Most of the activity looks to be post- frontal, so thunder potential looks low at this time. A decent temperature gradient expected as the southern portions remain in the warm sector for a good portion of the day. Highs are forecast to range from around 70 north to the low 80s south. && .LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/... The high pressure wedge is expected to persist Thursday into Friday before shifting east in response to a digging upper trough to the west. Thursday looks the coolest, followed by late-day warming on Friday. Saturday will most likely be warm though Sunday could be unsettled as an upper low crosses the Deep South. && .AVIATION /02Z MONDAY THROUGH FRIDAY/... VFR. Extended Aviation Outlook: Low ceilings possible late Wednesday into early Thursday. && .MARINE... Tonight: The surface pressure gradient will relax tonight as complex low pressure off the northeastern seaboard pulls away into the Atlantic. Lingering thermal gradients will still support 10-15 KT offshore. Seas will range from near 2 FT near shore to around 4 FT closer to the Gulf Stream. Monday through Friday: Quiet marine conditions will prevail early in the week as high pressure prevails. A backdoor cold front will slowly approach from the north Tuesday and then will cross through the waters on Wednesday. Winds and seas will increase in its wake as high pressure wedges down the eastern seaboard. Small Craft Advisories will likely be needed for most if not all of the coastal waters starting as early as Wednesday afternoon and persisting into Thursday. Conditions are expected to improve on Friday as high pressure shifts offshore. && .CHS WATCHES/WARNINGS/ADVISORIES... GA...None. SC...Frost Advisory from 4 AM to 8 AM EDT Monday for SCZ040-042>045- 050-052. MARINE...None. && $$
Area Forecast Discussion
National Weather Service Cleveland OH
1047 PM EDT Sun Mar 19 2017 .SYNOPSIS... High pressure over the Ohio Valley will move off to the east tonight. A weak cold front will move southeast through the region Monday evening, with a stronger cold front moving south through the region Tuesday night. Arctic high pressure will build in from the northwest Wednesday into Wednesday night before moving east of the area Thursday. && .NEAR TERM /THROUGH MONDAY/... Update...Removed fog chances west half of the area. Bufkit shows boundary layer flow increases through the night increasing the potential for mixing. The upper level moisture will be increasing as well ahead of the next system. As to pops...the HRRR suggests rain may reach into extreme western CWA just before/around dawn so put in a low chance pop. Other minor adjustments to sky grids as well. Original...Low clouds continue to hang around everywhere, with the only exception being over parts of Lake Erie. We will likely see at least some breaks in the clouds this evening with a continued decrease in cloud coverage into the overnight hours. Dry weather is expected tonight with partly to mostly cloudy skies. Winds will remain light and turn out of the south overnight ahead of an approaching weak cold front. We could still see some areas of fog develop after midnight or so, though whether the small amount of low-level moisture present manifests as fog or low stratus clouds is still a little uncertain. It will likely be a combination of both. Rain showers will begin to move in from the west Monday morning and continue to spread eastward through the afternoon hours. This will occur ahead of and along the cold front, which is progged to pass through the region Monday evening. Temperatures should be able to rise to the middle and upper 40s ahead of the frontal passage. && .SHORT TERM /MONDAY NIGHT THROUGH WEDNESDAY NIGHT/... The rain will be coming to an end from west to east Monday evening into early Monday night. Temperatures will fall to the lower and middle 30s in the wake of the front, but will recover nicely Tuesday with highs in the middle to upper 40s. A few southern and western locations may touch 50 degrees. A weak disturbance will pass well south of the area Tuesday, but may trigger a few rain showers across extreme southern portions of the forecast area Tuesday afternoon into Tuesday evening. A much stronger cold front will move south through the region Tuesday night as an arctic high begins to build in from the northwest. This will drop temperatures Tuesday night into the middle 20s, with highs on Wednesday only reaching the lower to middle 30s most places, and temperatures likely struggling to get out of the 20s in northwest Pennsylvania. Can`t rule out a few lake-effect snow showers/flurries Tuesday night across northwest Pennsylvania behind the front, but the air mass is quite dry, so only carried a slight chance. A mostly sunny sky is expected Wednesday, with just a few clouds moving in Wednesday night. The mostly clear sky Wednesday night will allow temperatures to fall into the teens out east and the low 20s across western areas. && .LONG TERM /THURSDAY THROUGH SUNDAY/... High pressure starting off the day overhead on Thursday will shift to the east coast allowing southerly return flow to develop. An increase in cloud cover is expected through the day with late day highs approaching normal values for late March. Scattered showers will accompany a warm front lifting north across the area Thursday night into Friday morning ahead of the building ridge aloft. Moisture axis will lift to the northeast on Friday with a break in showers and temperatures warming into the 50s and low 60s. Closed upper level low over the plains then expected to make slow eastward progress through the Ohio/Tennessee Valley over the weekend. Showers will return with temperatures being the more difficult part of the forecast. The track of the low will influence how long we stay in the warm sector before the cold front is pulled back south with cool flow off the lake returning. Have followed a blended forecast approach given the uncertainty with mild conditions continuing on Saturday followed by a cool down on Sunday. && .AVIATION /00Z Monday THROUGH Friday/... The strato cu deck continues to erode from the edges. If current trends continue...which is questionable...all of the area should lose their low cigs overnight. At the same time high clouds will continue to spill into the region from the NW. This should help prevent fog from developing. A warm front will move over the area on Monday. Expect MVFR cigs to return by early afternoon with showers soon after. Light and variable flow will become southeast overnight and southerly behind the warm front. OUTLOOK...Non-VFR returns Monday night then again on Tuesday night into Wednesday across NE Ohio/NW PA. && .MARINE... Favorable marine conditions are expected to continue on Lake Erie through Tuesday. High pressure overhead will build to the southeastern states with light southerly winds developing overnight. A trough extending from low pressure near Hudson Bay will move across the lake on Monday with a weak cold front settling south Monday night. A stronger cold front will push south across the lake on Tuesday night with northerly winds increasing to 15 to 20 knots with waves near 4 feet. A Small Craft Advisory may be needed for a window of time late Tuesday into Wednesday morning. Strong high pressure will build south out of Canada behind the front with good marine conditions returning on Thursday. && .CLE WATCHES/WARNINGS/ADVISORIES... OH...None. PA...None. MARINE...None. && $$ SYNOPSIS...Mottice NEAR TERM...TK/Mottice SHORT TERM...Mottice LONG TERM...KEC AVIATION...Kubina MARINE...KEC
Area Forecast Discussion
National Weather Service Grand Rapids MI
1029 PM EDT Sun Mar 19 2017 LATEST UPDATE... Update .SYNOPSIS... Issued at 325 PM EDT Sun Mar 19 2017 A cold front will move across the state Monday triggering some light rain and perhaps a thunderstorms south of I-95. Dry and colder weather is expected Wednesday with highs only in the mid 30s. Then a warm up into the 50s will occur by the end of the week. && .UPDATE... Issued at 1028 PM EDT Sun Mar 19 2017 I have added the chance for thunderstorms to our western CWA tonight as there is an area of elevated instability that shows up nicely in the RAP soundings. The instability is coming from air above 700 mb so nearly no chance of mixing this the ground but above 700 mb there is 700 to 900 j/kg crossing the western CWA between midnight and 4 am or so. This is on the nose of the best 1000/850 moisture transport. There are thunderstorms out there now based on lightning data and surface observations (over NE WI and soon northern Lake Michigan). Some brief down pours are surely possible from these storms and small hail would not be out of the question as there is a fair amount of the cape in the -10 to -20c range. && .SHORT TERM...(This evening through Tuesday night) Issued at 325 PM EDT Sun Mar 19 2017 Forecast concerns deal with pcpn chances later tonight and Monday. A cold front currently over the Mississippi Valley will move east through the cwa Monday. Ahead of it, instability has developed over Missouri and some of this instability will move toward far southern Lower Michigan tonight. We`ll see showers develop ahead of the approaching front and a few elevated storms are possible tonight south of I-94. Upper level support is lacking with this system; it remains in Canada. Thus pcpn amounts will be limited. However, as a wave develops along the front over Illinois tonight, moderate to high pops seem warranted Monday. After the front passes, high pressure quickly builds in and Monday night through Tuesday night will be dry. .LONG TERM...(Wednesday through Sunday) Issued at 325 PM EDT Sun Mar 19 2017 The main challenge with the long term deals with the precipitation type for Thursday night. The latest incoming data suggests this will be mainly a rain event. The initially low wet bulb temperatures from the High Res Euro...could support a brief period of snow...but the warm air advection is strong and is shown to quickly warm up the soundings...even for Harrison. The GFS is too warm for snow there through the night with 800 mb dewpoints of 3.7 deg C at 06z for Harrison. We will need to monitor the surface temperatures...especially the interior northeast zones. The pattern does suggest a small risk for zr if we end up with surface temperatures a few degrees cooler. It looks like a rather cool day for Wednesday. The 925 mb thermal trough will be in place to start the day with values around -12 to -13 deg C. Despite the abundant sunshine the weak flow with high pressure overhead will support only slow modification of the airmass. Some locations look likely to stay below freezing. && .AVIATION...(For the 00Z TAFS through 00Z Monday evening) Issued at 731 PM EDT Sun Mar 19 2017 It would seem to this forecaster that for the most part the showers will largely bifurcate the GRR TAF sites overnight. Some of the convection is exiting northeast across Lake Superior as I write this, that will stay well north of here. Meanwhile a southern stream shortwave will track it`s convection largely south of Michigan overnight. I could see a few scattered showers coming through the AZO and BTL TAF sites even so. While an elevated thunderstorm is not out of the question a quick look at the SPC SREF makes is clear the thunderstorms will be south of I-94 overnight. There is just the slightest hint that afternoon convection, developing just north of the warm front associated with the developing low over western IL could make it as far north of I-94 Monday afternoon, I did not play this in the TAFs but you should be aware of this. If this makes it into Michigan these have a better chance of being thunderstorms. Once the convention misses the TAF sites to the south (more or less) low clouds will follow and hold most of the day. Drizzle i not out of the question. I would expect clearing around or just after 00z Tuesday. && .MARINE... Issued at 325 PM EDT Sun Mar 19 2017 Southwest winds 10 to 20 knots will create 2-4 foot waves during the next 24 hrs. A thunderstorm is also possible && .HYDROLOGY... ISSUED AT 1047 AM EDT SAT MAR 18 2017 RIVER LEVELS ARE RUNNING AROUND NORMAL TO A LITTLE BELOW NORMAL. WITH LESS THAN A HALF INCH OF PRECIPITATION EXPECTED THROUGH THIS WEEKEND AND THEN NO ADDITIONAL PRECIPITATION UNTIL FRIDAY, NO FLOODING IS EXPECTED ACROSS THE AREA INTO NEXT WEEKEND. THE PRECIPITATION NEXT WEEKEND MAY BE ENOUGH TO PUSH RIVER LEVELS UP, BUT THEY SHOULD REMAIN BELOW BANK FULL. && .GRR WATCHES/WARNINGS/ADVISORIES... MI...None. LM...None. && $$ UPDATE...WDM SYNOPSIS...04 SHORT TERM...04 LONG TERM...MJS AVIATION...WDM HYDROLOGY...63 MARINE...04
Area Forecast Discussion
National Weather Service Huntsville AL
808 PM CDT Sun Mar 19 2017 .NEAR TERM...(Tonight) Issued at 807 PM CDT Sun Mar 19 2017 A fairly quiet weather evening as NW to SE oriented ribbon of scattered low to mid level cloud cover (within the eastern flank of a ridge axis centered over the northwest Southern Plains) moves across the region. These clouds (mainly between 6-8 kft) are overrunning a substantial dry air layer. This dry air layer has been detected via 00Z RAOBs and GOES 16 WV imagery from the departing anticyclone over the OH river Valley and oncoming anticyclone from the Southern Plains. Though there have been some brief reflectivity echos over central TN and northwest Alabama, any very light precip that is occurring is likely evaporating as are the clouds. ECAMs and HRRR models show the possibility of rainfall as moisture, warm air advection, and weak omega values increase later tonight aloft and again tomorrow as the ridge axis slowly shifts east. At this point, not inclined to introduce POPs for late tonight with the now dissipating cloud cover; and tomorrow morning due to the likely slower moisture advection to the northeast and subsequent saturation of the low-level profile before the lift moves northeast. On the temperature and dewpoint forecast, only minor adjustments were necessary. Did notice that the sky cover forecast appears to need some tweaking for the current dissipating band of clouds, and additional clouds that are expected early in the morning. Otherwise, the rest of the forecast looks fine. .SHORT TERM...(Monday through Tuesday night) Issued at 240 PM CDT Sun Mar 19 2017 The warming trend continues on Mon, as weak upper ridging over the mid/srn Plains states moves ever slightly to the e. Sly flow should be well entrenched across the region as well, as Gulf moisture streams back into the area. Highs on Mon look to rebound back into the lower/mid 70s, before afternoon temps climb further on Tue, with highs in the upper 70s/near 80F for most spots. A weak cold front is still xpcted to approach the area from the n heading into Tue evening. SBCAPE values during the day Tue look to climb into the 1000-1500 J/kg range, as low level instability spreads ewd ahead of the approaching sfc boundary from the n. Effective/Bulk Shear values though are not that impressive along/just ahead of the front, with values mainly around 30kt or less. Given a fairly linear profile out of the w in the lower levels, a line of showers/tstms may develop just ahead of the front during the afternoon/early evening hrs Tue. Main wx hazards with any stronger storms look to be brief gusty winds and perhaps some small hail, to go along with locally heavy rainfall mainly along/n of the TN River. The tstm threat should then weaken quite a bit going into the late evening hrs Tue, as energy/instability wane with the loss of daytime heating. .LONG TERM...(Wednesday through Saturday) Issued at 240 PM CDT Sun Mar 19 2017 The weak cold front should then continue to drift swd into the local area and diminish as the afternoon hrs progress Wed, as any low level convergence along the front weakens and lingering mid/upper forcing gets sheared to the se. Rainfall likewise should taper off to the s heading into the afternoon period Wed, with the weakening cold front. Relatively benign wx conditions are then xpcted Thu into Fri, as another upper ridge pattern makes its way ewd across the cntrl Gulf states and sfc high pressure out of the Great Lakes/OH Valley regions drops into the mid Atlantic Coast. The latter half of the global models are still hinting at a stronger cold front and associated upper trough axis approaching the cntrl TN Valley from the w heading into next weekend. Developing return flow across the region should help usher further Gulf moisture back into the area, as a low level sly fetch increases ahead of the oncoming cold front. While buoyancy/instability look to be a tad bit weaker with this next cold front late Fri into Sat, Bulk/Effective Shear values still look to climb into the 40-50kt range given an increasing sly fetch/low level jet. While some differences remain with the exact strength/timing of this next front/storm system, multiple sfc waves developing along the srn edge of the cold front may enhance the low level curvature in the wind profile, provided the inflow into the area is not diminished from the s. Pending model runs over the next couple of days will hopefully provide a little more clarity going into Fri/Sat. Nevertheless, showers/tstms should certainly be on the increase along/ahead of this next front, as it begins to move ewd across the local area during the first half of the weekend period. && .AVIATION...(For the 00Z TAFS through 00Z Monday evening) Issued at 613 PM CDT Sun Mar 19 2017 VFR conditions are expected across N AL/S Middle TN for the next 24 hours. Low-cloud cover that may move over the TN Valley should remain on the low end of VFR. In addition, there could be some light -DZ/-RA late in the period (between 20/15Z-21/00Z) but very isolated in nature. Thus, did not include in forecast at this time. && .HUN WATCHES/WARNINGS/ADVISORIES... AL...NONE. TN...NONE. && $$ NEAR TERM...SL.77 SHORT TERM...09 LONG TERM...09 AVIATION...SL.77 For more information please visit our website at weather.gov/huntsville.
Area Forecast Discussion
National Weather Service Lincoln IL
850 PM CDT Sun Mar 19 2017 .UPDATE... Issued at 837 PM CDT Sun Mar 19 2017 Current forecast is on track. HRRR still forecasting the enhancement of the LLJ over Missouri and into Iowa through the remainder of the evening. As the strong moisture advection riding the jet impacts the effective boundary over Iowa significant lift is expected. MUCape is already running over 1000 J/Kg in that area per SPC Mesoanalysis, but bufkit soundings show that convection will remain elevated with a nice inversion in place below the warm advection, thereby limiting impacts to potential hail. HRRR 23Z and 00Z are showing development in the 1-2 AM window in eastern Iowa and then system expanding SE into the northern half of the forecast area. The model trend is a bit further south than the previous runs and will have to be watched closely. && .SHORT TERM...(This evening through Monday) ISSUED AT 247 PM CDT Sun Mar 19 2017 Temperatures have reached the 50s across the forecast area by 2 pm, despite the bands of mid and high clouds drifting through. Scattered showers and thunderstorms continue to trudge eastward across eastern Missouri. Latest RAP model does have the northern edge of the showers clipping areas around Jacksonville by late afternoon, while the HRRR and NAM-Nest keep it just to our southwest. May need to add some slight chance PoP`s over the far southwest CWA for a few hours. Main concern remains with the overnight convection. Latest surface map showing low pressure centered over north central Nebraska, with a frontal boundary extending northeast into southeast Manitoba. With time, this boundary should focus more into a warm front over Iowa as the low moves eastward. A low level jet will focus along this boundary and lead to some convection developing by late evening over eastern Iowa. The GFS has been very aggressive with development and bringing it into the northwest CWA as early as 9-10 pm, but am thinking that a post-midnight arrival is more likely. Steep mid- level lapse rates of around 8C/km will likely result in some hail with the stronger storms, with the SPC Day1 outlook featuring a marginal severe weather risk over the northern third of the CWA. How much of this lingers into Monday is also a question. While the initial band of showers/storms shifts into Indiana early Monday, the high-res models try to develop some additional convection over the eastern CWA with the arrival of the front itself early afternoon. A little MUCAPE remains by this point, but will be on the wane, so will only mention isolated thunder over the east in the afternoon. Temperatures over a good chunk of the CWA should manage to reach the 60s ahead of the front, but have kept areas from Bloomington to Danville in the mid-upper 50s as the clouds and rain will be a bit more prevalent there. .LONG TERM...(Monday night through Sunday) ISSUED AT 247 PM CDT Sun Mar 19 2017 A cold frontal boundary will slowly drop into southern Illinois Monday night, shifting the focus for rain south of our forecast area. A fast moving shortwave will trigger a period of showers Tuesday into Tuesday evening, with Likely chances of rain focusing on Tuesday afternoon during peak forcing for precip. The ECMWF continued its southern bias with the band of rain across our area as opposed to the GFS and NAM farther north expansion of rain. However, most of our forecast area should see at least light rain. Canadian high pressure will suppress that wave and residual moisture southward later Tuesday night, setting up a chilly but mostly sunny day for Wednesday. Low temps Wednesday night are expected to dip below freezing in most areas in the cold air mass, despite increasing cloud cover. Southerly return flow will become established behind the departing high pressure later Wed night, with a few light snow showers possible in our far western counties around sunrise on Thursday. The warm advection band of precip will lift north through Illinois on Thursday, changing snow chances to rain by Thursday afternoon. Dry conditions are expected to re-develop Thursday night as central IL enters the warm sector. Rain chances will ramp up again Friday afternoon as a developing low pressure center approaches Illinois from the Plains. There is better agreement in the extended models showing the low passing across Illinois on Saturday afternoon and Sat evening, with likely to categorical PoPs across the board during that time. Instability and low level moisture supply appear sufficient for thunderstorm development, especially Friday night and Sat morning. The slow moving nature of the low per the GFS and Canadian caused the extension of precip chances into Sunday morning, with a few showers southeast of I-70 Sunday afternoon. Friday continues to look like the warmest day of the next week, with highs in the mid to upper 60s. Depending on the speed of the low pressure center next weekend, highs could reach the low 60s on Saturday. && .AVIATION...(For the 00Z TAFS through 00Z Monday evening) Issued at 620 PM CDT Sun Mar 19 2017 Remnant clouds from earlier convection over Missouri will bring some VFR CIGS briefly to KSPI over next few hours. Otherwise, VFR conditions will likely hold until around sunrise or so. Exception will be near any thunderstorms that develop after 06z tonight. There is still some range in model solutions with the GFS the most robust at developing widespread precip this evening. This seems questionable given the lack of trigger and location of short-wave ridge axis over Illinois. Most of the convective allowing models support an area of elevated convection developing to our north and then saging southward into the area after 07z. Given the forecasted location of the LLJ and the boundary at that level this seems to be a more realistic evolution and will generally be followed. The cold front associated with the initial wave is expected to push across the area Monday afternoon. Ahead and along the front MVFR CIGs appear possible with even some IFR conditions temporarily at KBMI. Conditions should improve after the frontal passage toward the end of the TAF valid period. 170-220 winds should remain gusty ahead of the front overnight and Monday with occasional gusts to around 20 knots. Expect 350-040 winds around 10 kts after passage. && .ILX WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...Barker SHORT TERM...Geelhart LONG TERM...Shimon AVIATION...Barker
Area Forecast Discussion
National Weather Service Chicago/Romeoville, IL
925 PM CDT Sun Mar 19 2017 .UPDATE... 922 PM CDT No significant changes to going forecast though did nudge highest PoPs a little farther south to reflect latest model trends and expected placement of the low level jet. Scattered high based showers are moving southeast across Wisconsin this evening ahead of a cold front, and a couple thunderstorms have been able to develop ahead of the front farther north in Central Wisconsin. It`s possible to see some precip across northern Illinois within the narrow and weak instability axis, but better dynamics are in place across central and northern Wisconsin and think there is a better chance for areas north of the I-88 corridor in Illinois to remain dry this evening. Main focus this evening and tonight though will be increasing convection associated with a low level jet to our west/southwest. Guidance has been somewhat consistent this evening indicating the low level jet setting up across Missouri into far southeastern Iowa this evening with convection increasing around or just after midnight. Latest SPC meso-analysis and 00Z DVN Raob indicate strong MUCAPE in excess of 1000 J/kg just west of the CWA. Meanwhile, LLJ is progged to ramp up over the next couple hours with strongest moisture convergence focused from far NE MO/SE IA southeast into central IL. Expect this will be the region of strongest convection with storm motions off to the ESE. Think that greatest severe threat will stay closer to the LLJ convergence to our west/southwest where the highest instability will be in place which quickly decreases farther east. This should result in a fairly minimal severe threat for the local CWA with elevated hailers still the primary concern for any stronger storms that are able to persist into the local area. As mentioned earlier, nudged the highest PoPs farther south given the aforementioned thoughts with support from latest runs of the HRRR and RAP which are trending slightly farther south as well. Deubelbeiss && .SHORT TERM... 210 PM CDT Through Monday... After a pleasant and seasonal (though cool at the lake) Sunday with partly cloudy conditions and modest winds, our focus will shift to shower and thunderstorm chances tonight into Monday. A lead shortwave riding the periphery of a flattening ridge across the plains is leading to convection along a warm frontal boundary across Missouri. This activity will dissipate, but additional shortwave energy will propagate east along the frontal boundary in an area of increasing moisture return ahead of significantly increasing southwesterly low level jet. At this point the best moisture return and theta-e advection will be across our southwestern counties where the latest high- resolution guidance is suggesting an expansion of shower and thunderstorm coverage tonight. Initially this will be focused across Iowa this evening, but the RAP/HRRR suggest enough moisture convergence north of the front and some decent elevated instability to suggest a swath of showers and storms in our area. The favored areas for storms will generally be south as the night progresses toward daybreak. The instability is enough to be concerned about some severe hail with the instability extending through the hail growth region and decent shear though marginal in the cloud bearing layer, and therefore the threat is marginal and consistent with the SPC outlook. The main focus will be after midnight into early Monday, with better chance of hail largely southwest of the core of the Chicago metro area based on latest convective allowing model guidance, but it is certainly a non-zero threat farther north. The shortwave trough axis will approach Monday morning with the cold front, which will likely continue the chance of showers during the morning hours, possibly redeveloping for our northern areas including the Chicago area. The main warm frontal boundary will generally slide east along our southern counties, thus we never truly get into the warm sector ahead of the low. And while the northern stream cold front will shift into northern Illinois later morning, it will take a bit longer south which will linger the shower chances for most of the day for these areas. Expect cooling in Illinois, especially lake areas in the afternoon. The instability axis gets shoved farther south but not completely out of the area until the cold front arrives, so will need to hang onto the thunder mention into the morning and it is possible the marginal risk may have to shift north a bit on Monday. KMD && .LONG TERM... 259 PM CDT Monday night through Sunday... More energetic shortwave energy and associated precip will shift south of the CWA by Monday evening, with high pressure expected to build across the area Monday night into Tuesday. Cold advection on the backside of this system will return a cooler/drier air mass to the region, especially by Tuesday. Next chance of precip does appear to be on Tuesday, although confidence is lower with this chance owing to some placement and timing issues. Upstream shortwave anticipated to drop southeast through the region during this time, as baroclinic zones tightens up. With this setup, a narrow axis of developing precip seems probable and at this time, a favored location would be over the southern CWA. Expected highs/boundary layer conditions would support all liquid at this time, but will continue to monitor for at least a low potential for a rain snow mix. With anticipated colder thermal profile aloft, it looks like if enough forcing were to occur to cool the entire profile, then snow could be possible. Too early to tell at this time though, and have maintained only rain for Tuesday. Any precip then sags southward Tuesday evening with further expansion of the high to the north. Much colder air filters south and with this high moving more overhead, Tuesday night is looking to be a chilly night. However, the CWA may stay on the outer fringe of this high and tighter gradient. This would allow the winds to possibly stay more elevated and lessen the extent of the cooling this night. Dry weather then expected to continue Wednesday into Wednesday night. Large scale pattern begins to change though, with upper level ridge building overhead and warmer air returning to the region. Warmer temps expected Thursday and Friday, but precip/rain and possibly thunder chances increase by late Thursday into Friday. Rodriguez && .AVIATION... For the 00Z TAFs... Multiple aviation concerns, with the higher confidence on low clouds developing Monday morning and lingering into the afternoon. For the Chicago area airports, the overall concerns are: - Likelihood of scattered TSRA in the region overnight, most favored southwest of the airports, though could be close. - Possibility of another round of -SHRA and some thunder late Monday morning into the early afternoon. - IFR cigs and MVFR visibility likely at some point Monday morning into early afternoon, with LIFR cigs possible. - South winds tonight becoming northeast early Monday afternoon, likely overlapping IFR cigs. Scattered thunderstorms are expected to develop across southeastern/eastern IA and western and possibly northwestern IL by 06Z. This activity will translate southeast, so whether or not it impacts the TAF sites will depend on just how far north it develops. No matter what, the higher coverage and deeper tops are probable to be southwest of the TAF sites. Diminishing wind speeds on Monday morning will allow for ceilings to lower to IFR with high confidence, however, the rate in which this drop occurs has low confidence in the forecast. Gradually lowering visibility is also likely during Monday morning, though dense fog is not favored at this time. As a cool front approaches, the possibility of showers/rain increases in the 15Z-20Z window before this activity shifts southeast. The cool front passage will turn winds northeast with medium-high confidence in speeds over 10 kt, and the timing of the wind shift has medium confidence. Clouds will likely remain IFR given flow off the lake. MTF && .MARINE... 259 PM CDT High pressure which has been situated across the lake for much of the day continues to shift to the east at this time. This trend will continue this evening and tonight with winds expected to quickly increase this afternoon. Expect winds of up to 30 KT to be in place by this evening over the north half with winds of 15 to 25 KT expected over the south half. Winds should stay in the 10 to 20 KT range along the nearshore tonight. The gradient and winds do weaken by early Monday morning, but anticipate speeds to increase once again later in the day Monday as a wind shift to the north occurs. Although some slight variation may occur, expect northerly winds to persist Monday night into Tuesday with an increase in speeds expected once again. Speeds Tuesday night into early Wednesday could reach gales for a time. Confidence is low at this time, and so have maintained mention of 30 KT in the open water forecast. Rodriguez && .LOT WATCHES/WARNINGS/ADVISORIES... IL...None. IN...None. LM...None. && $$ VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE) FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT: WWW.FACEBOOK.COM/NWSCHICAGO WWW.TWITTER.COM/NWSCHICAGO WWW.YOUTUBE.COM/NWSCHICAGO
Area Forecast Discussion
National Weather Service Marquette MI
734 PM EDT Sun Mar 19 2017 .SHORT TERM...(This evening through Monday) Issued at 341 PM EDT SUN MAR 19 2017 Strong upper trough moving from northern Manitoba to Hudson Bay will push deep 987mb low from far northern Manitoba to southern Hudson Bay by 12z Mon while deepening to 976mb. Sfc trough tied to the low extends south to southern Mantioba and eastern North Dakota. Warm front extends from that trough to the central Plains. SSE flow ahead of trough is graudally bringing in warmer conditions, though it has been a slower rise over Upper Michigan as flow is mainly coming off Lk Michigan and there are sct-bkn middle clouds. Soundings upstream indicated steeper mid-level lapse rates but they were also dry below moist layer h7-h5. Stronger shortwave stays north of Lk Superior this evening but tail end of that wave along with increasing h85-h7 moisture advection moving in from the west. That forcing along with instability aloft results in isold-scattered showers developing over MN and then moving across Lk Superior and Upper Michigan through the evening. Certainly does not feel like a thunder day outside attm as it cooler and dry, but if convection can develop late this aftn into this evening there could be thunder with mid-level lapse rates over 8c/km and RAP and HRRR indicating mucapes up to 400 j/kg. Conditional potential but with low freezing levels would not take much to get small hail in even the stronger showers. Strong winds aloft with h85 winds up to 50 kts but think risk of having these winds surface is low as all the shra and any tsra would be based at h7 or 8-10kft. All precip should be clear of eastern cwa by 06z, though low clouds and/or fog may linger through much of night. Best chances of fog would be over cntrl and east. Low pressure trough crosses late tonight switching winds to the NW on Monday. Low clouds will give way to plenty of sunshine in the aftn as drier air moves in as large high building over cntrl Canada. Cooler air gradually moves in but most areas should be able to reach the 40s. Could even be warmer over the scntrl with downslope NW winds and as there is little if any snow cover left. For those areas, mixing to h85 temps 1-4c supports max temps reaching into the low 50s. .LONG TERM...(Monday night through Sunday) Issued at 249 PM EDT SUN MAR 19 2017 Models suggest that a progressive pattern will prevail into next weekend. After a brief cooldown from Tue into Wed with n-nw flow LES, moderating conditions will follow by Thursday into Friday as a low pressure system with widespread precipitation moves affects the region. Temperatures will drop behind the system but should still remain at or above normal. Monday night through Wednesday, a shortwave trough sliding through nrn Ontario will drag an arctic front through the nrn Great Lakes Tuesday morning with much colder air dropping into the area on nnw winds. 850 mb temps are expected to fall to around -18C by 00z/Wed which will provide enough instability for LES development. However, LES intensity will be limited by relatively low inversion heights around 4k-5k ft with a very dry 850-700 mb layer and very dry low level air upstream. The LES should diminish Wed morning as winds become light and anticyclonic as the dry airmass associated with 1040 mb high pres builds into the region. Expect Snowfall amounts in the 1 to 2 inch range per 12 hours at most and SLR values above 20/1 with DGZ through the convective cloud layer. Thursday-Sunday, Model/ensemble spread is still relatively high with the evolution of the cntrl plains shortwave and sfc low heading toward the Great Lakes. The ECMWF and CMC slide the stronger 500 mb low more to the east. There is still decent moisture transport toward the cwa and support for pcpn with a nrn stream shrtwv and fgen associated with the right entrance of the jet from nrn Ontario into Quebec. This would still keep the heavier pcpn and warmer air farther south compared to the GFS/GEFS. However, there is enough agreement to maintain high pops for mixed pcpn that would likely change to rain Friday as a warm layer spreads into the cwa. Some snow or lake enhanced snow may be possible as colder air moves in behind the system. && .AVIATION...(For the 00Z TAFS through 00Z Monday evening) Issued at 734 PM EDT SUN MAR 19 2017 Ahead of a low pres trof moving across the area overnight/Mon morning, a band of sct -shra currently exiting western Upper MI will affect central Upper MI, including KSAW, for the next couple of hrs. Not expecting conditions to fall blo VFR in the shra, though some shra could produce grauple/small hail and potentially a lightning strike. After the pcpn ends, lower clouds/fog may eventually develop at KSAW. For now, only lowered conditions to MVFR, but not of the question for conditions to fall to IFR. With the passage of the trof, conditions should improve quickly to VFR Mon morning. At KIWD/KCMX, low-level jet ahead of the trof will lead to LLWS this evening. Otherwise, VFR conditions are expected to prevail at both terminals thru the fcst period. && .MARINE...(For the 4 PM Lake Superior forecast issuance) Issued at 341 PM EDT SUN MAR 19 2017 At this time, no gales or heavy freezing spray are expected through this week. Prevailing winds will mostly be in the 20-30 kt range. Strongest winds will be Mon night into Tue evening as cold air moves across Lk Superior. && .MQT WATCHES/WARNINGS/ADVISORIES... Upper Michigan... None. Lake Superior... None. Lake Michigan... None. && $$ SHORT TERM...JLA LONG TERM...JLB AVIATION...Rolfson MARINE...JLA
Area Forecast Discussion
National Weather Service Shreveport LA
1058 PM CDT Sun Mar 19 2017 .DISCUSSION... Just sent out a quick update to extend patchy fog wording northward to include Monroe and El Dorado based on HRRR visibility guidance. Fog development expected around daybreak. Update already out. /05/ && .PRELIMINARY POINT TEMPS/POPS... SHV 61 87 60 87 / 0 0 0 0 MLU 59 86 58 85 / 0 0 0 0 DEQ 58 84 56 84 / 0 0 0 0 TXK 62 85 58 84 / 0 0 0 0 ELD 59 86 56 85 / 0 0 0 0 TYR 63 87 61 86 / 0 0 0 0 GGG 61 87 61 86 / 0 0 0 0 LFK 61 87 60 87 / 0 0 10 0 && .SHV WATCHES/WARNINGS/ADVISORIES... AR...None. LA...None. OK...None. TX...None. && $$ 05