Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 04/15/18

Area Forecast Discussion
National Weather Service Burlington VT
1016 PM EDT Sat Apr 14 2018 .SYNOPSIS... An active and dynamic weather pattern will be in place across the North Country through Monday night. An unseasonably strong frontal zone draped across the region will bring periods of light to moderate mixed precipitation tonight and Sunday. Areas of difficult travel are expected overnight and Sunday morning with icy and/or snow covered roadways developing. We`ll see the boundary lift northward as a warm front Sunday night into Monday as strong low pressure approaches from the Ohio Valley region. This will lead to periods of moderate to briefly heavy rainfall and the potential for minor river flooding during Monday and Monday night. Lastly, as the strong low pressure system approaches, areas of strong southeasterly winds will be possible on Monday, especially along the western slopes of the Green Mountains, where localized wind gusts in excess of 50 mph are possible. The weather pattern will trend drier toward the middle portion of the work week, though temperatures will generally remain slightly below seasonable levels for mid-April. && .NEAR TERM /THROUGH SUNDAY NIGHT/... As of 936 PM EDT Saturday...More tweaks to the forecast, mainly to keep the sleet/fzra line a bit further north tonight based off latest radar data and surface observations. KBTV has seen mainly -fzra all evening with brief periods of sleet mixing in. Early Lyndon State sounding confirmed a sharp warm nose around 750 mb to near 0C, but given -fzra/pl in many observations I have to believe that some mesoscale effects are occurring or alternatively that the max T aloft in the warm nose is just a tad warmer in some spots. Have also noticed that the primary dendritic snow growth zone is way up there (near 500 mb) and waffles in and out of saturation on several model depictions this evening across our northern counties. So it`s plausible that snow-growth processes are somewhat marginal in the main isentropic lift zone to the north of the front. Thus is the challenging nature of mixed-precipitation forecasting. With these slight adjustments snowfall totals were cut back to the south of a KSLK-KBTV-K1V4 line and icing amounts increased a bit along this line (up to 0.20 inches) by Sunday. Prior discussion... Maintained the Winter Weather Advisory areawide for tonight and Sunday, with travel conditions becoming increasingly icy after sunset this evening as pavement temps cool below 32F. The worst of the winter travel conditions will likely occur tonight into Sunday morning. Very dynamic pattern across the CONUS with deep mid-latitude cyclone across the central Plains, and an eastward extending cold front into PA/sern NY that is unusually intense (26F at BTV and mid-80s across central NJ). Generally looking at strong frontogenetic forcing developing within 850-700mb frontal zone across nrn NY and VT late this afternoon through the overnight hours, which will result in increasing coverage of steady light to moderate mixed wintry precipitation across the area. Initially, radar trends suggest the steadiest precipitation will be across far nrn areas. However, RAP and NAM-3kmWRF suggest coverage will also increase southward across the Adirondacks into central/s-central VT toward 02-03Z tonight. Vertical temperature profiles support a trend toward snow/sleet for the northern half of the forecast area, with sleet/freezing rain across portions of the nrn Adirondacks into s-central VT. Already seeing some light gaze on paved surfaces with temperatures in the mid-upr 20s and north-northeast winds 10-20mph. Roads should deteriorate significantly after sunset as pavement temperatures cool below freezing in most areas (the immediate CT River being a bit more marginal). Thus, will see accumulations of snow/ice on roadways overnight, and difficult travel tonight thru Sunday morning as a result. Snow and sleet amounts generally 2-5" across the north with generally one tenth or less of ice accumulation. Further south, should see less snow and sleet (1-3") with potential for more ice (0.2-0.3"). Generally not enough to create power outages, but ice on trees and powerlines may become an issue toward Sunday night/Monday morning as winds sharply increase along the western slopes of the Green Mtns. We may see the ice in trees and powerlines contribute to power outages during that time frame. Temperatures will generally fall into the low-mid 20s tonight. On Sunday, will see temperatures gradually climb into the 30-34F range from the Champlain Valley wwd, with sub-freezing temps generally locked in east of the Green Mtns. We`ll see the sfc boundary retreat northward as a warm front, with the steadier mixed precipitation ending in the morning. That said, will still see intermittent sleet/freezing rain across the region through the afternoon. Roads should warm above freezing in the Champlain Valley, allowing for some improvement by afternoon, but areas of icy conditions will persist elsewhere through the day. Winds generally becoming E to ESE at 5-10 mph. Overall coverage of rainfall (with some pockets of ZR remaining east of the Greens) increases Sunday night as large-scale trough and QG forcing increases newd from the Ohio Valley. Also anticipate PW values climbing to near 1" toward 12Z Monday. P-Gradient increases sharply after midnight, and we`ll see SE wind gusts potentially increasing to around 50 mph along the western slopes of the Green Mtns late Sunday night (and peaking during the day Monday - see next section). This may begin to cause some localized wind damage during the pre-dawn hours Monday. A High Wind Watch has been posted from 06Z Monday thru 03Z Tuesday. Will probably see orographically enhanced precipitation on the eastern slopes of the Greens during Sunday night given increasingly moist sely low-level flow. && .SHORT TERM /MONDAY THROUGH MONDAY NIGHT/... As of 425 PM EDT Saturday...The active weather continues Monday with multiple potential threats to the North Country. With this update, confidence has increased in the high wind threat and so a High Wind Watch has been issue for the western slopes of the Greens and the Flood Watch remains in effect for Monday afternoon through Tuesday. Monday morning a warm front will lift north through the region and we`ll see the wintry precip turn to all rain across the North Country. There will likely be breaks in the rain as the energy lifts north in scattered fashion. Soundings show some breaks in the cloud cover may be possible as there may be some brief windows where 1000-500mb RH drops to 50% but I tend to believe we`ll see mostly cloudy skies. In the afternoon hours a vort max will lift through the region and should be enough dynamical support to generate periods of moderate to heavy rain during the afternoon and evening hours. This additional rainfall will combine with snow melt to cause additional rises in main stem rivers with minor flooding possible. More details can be found in the Hydro section. Total rainfall will be highly dependent on the effect of the low level level jet which leads us to potentially the main threat with this system. A strong southeasterly low level 925-850mb jet will move into the North Country during the overnight hours Sunday night and persist Monday through the day. 925mb flow approaches 60-70kts just downstream of both the Greens and the western slopes of the Adirondacks. We are growing increasingly concerned with the potential for those stronger winds to mix down to the surface along with downsloping mountain breaking waves. A very strong inversion will be set up just about the ridge tops of the Greens and cross sections are showing a strong omega couplet on the western slopes of the Greens. With strong southeasterly winds already below the critical layer aloft, any mountain breaking waves will become trapped and propagate some of the much stronger winds all the way to the surface. The area of highest concern is the across Rutland and eastern Addison counties where mean boundary layer flow is upwards of 45-50kts. Given how the system is developing its not out of the realm that we see repetitive bursts of 50-60 mph gusts in that area. This is especially concerning given the precursor events with saturated soils and ice accumulation on powerlines and trees. The potential currently exists for scattered power outages all along the western slopes of the Greens with the highest potential across the southern Greens. Strong gusty winds will be possible across the rest of Vermont and northern New York but should only be in the 25-35mph range. The winds will persist throughout the daylight hours before the low level jet departs. && .LONG TERM /TUESDAY THROUGH SATURDAY/... As of 1216 PM EDT Saturday...The extended remains fairly active through the mid week as the upper level cyclone remains over the region through Wednesday. Expect daily chances for rain and mountain snow showers until the upper level low moves off to our east. Westerly flow will persist under the low and we`ll continue to see well below normal temps through Tuesday night. By Wednesday afternoon the low should be departing as high pressure starts to build in briefly. Expect southerly flow with warm air advection to push temps back towards normal with highs likely in the upper 40s to near 50 on both Thursday and Friday. Either Thursday night or Friday the next clipper type system will begin to push into the North Country and lead to more widespread precip. Based on thermal progs it should be all rain with no wintry precip to deal with. There`s quite a bit of timing differences so we`ll need to continue to watch for how that system evolves as the GFS brings in a faster much stronger system with higher PWAT`s and in turn quite a bit more qpf than the EC. Those details will become clearer as we come out of the weekend and see how the current low pressure system moves out of the region. && .AVIATION /00Z SUNDAY THROUGH THURSDAY/... Through 00Z Sunday...A frontal zone remains draped across the forecast area, bringing mixed precipitation that is resulting in highly variable flight conditions this evening. Expect the precipitation to continue overnight as a mix of mainly snow/sleet at KBTV/KPBG/KMSS/KSLK/KMPV. These sites will see periods of heavier precipitation through the night as the axis of heaviest precip shifts slightly north or south. Ceilings and visibilities will range from mainly MVFR/IFR conditions with brief periods of LIFR conditions possible during heavier snow. By Sunday afternoon, most sites will transition to freezing rain or plain rain that will weaken in intensity through the afternoon. At this point, should see some short-lived improvement to low VFR conditions at KPBG/KBTV, while KMSS/KMPV/KSLK should at least improve to widespread MVFR conditions. KRUT will remain south of the main front, and will see predominantly freezing rain that will last through the overnight hours. Winds will generally be from the north/northeast at 5 to 15 knots, with the exception of KMSS, which will see channeled northeasterly flow around 15 kts with gusts to 25 kts. Outlook... Sunday Night: Mainly VFR, with local MVFR possible. Strong winds with gusts to 40 kt. Likely RA, Likely FZRA. Monday: Mainly MVFR, with areas VFR possible. Strong winds with gusts to 45 kt. Likely RA, Chance FZRA. Monday Night: Mainly MVFR, with areas IFR possible. Likely SHRA, Likely SHSN. Tuesday: Mainly MVFR, with local VFR possible. Chance SHRA. Tuesday Night: Mainly MVFR, with areas VFR possible. Chance SHSN, Chance SHRA. Wednesday: MVFR. Slight chance SHRA, Slight chance SHSN. Wednesday Night: MVFR/IFR conditions possible. Chance SHSN, Chance SHRA. Thursday: Mainly MVFR, with local IFR possible. Chance SHRA. && .HYDROLOGY... As of 445 AM EDT Saturday...A flood watch continues for Monday afternoon through Tuesday afternoon. Moderate to localized heavy rainfall on Monday will combine with snow melt to cause sharp rises on local waterways. Current forecasts indicate some rivers may reach minor; those river gages with the best chances of exceeding flood stage include the Winooski River at Essex Junction (ESSV1), Otter Creek at Center Rutland (CENV1), the Mad River at Moretown (MOOV1), and the East Branch of the Ausable River at Ausable Forks (ASFN6). Persons with interests along area waterways should remain alert for rapidly changing river conditions and stay tuned to further developments on this situation. && .BTV WATCHES/WARNINGS/ADVISORIES... VT...Flood Watch from Monday afternoon through Tuesday afternoon for VTZ001>012-016>019. Winter Weather Advisory until 8 PM EDT Sunday for VTZ001>012- 016>019. High Wind Watch from late Sunday night through Monday evening for VTZ011-016>019. NY...Flood Watch from Monday afternoon through Tuesday afternoon for NYZ026>031-034-035-087. Winter Weather Advisory until 8 PM EDT Sunday for NYZ026>031- 034-035-087. && $$ SYNOPSIS...Banacos NEAR TERM...Banacos/JMG SHORT TERM...Deal LONG TERM...Deal AVIATION...RSD HYDROLOGY...Deal
Area Forecast Discussion
National Weather Service State College PA
1031 PM EDT Sat Apr 14 2018 .SYNOPSIS... A backdoor cold front will push southeast across the area tonight and early Sunday. A strong storm system will move through the region late Sunday into Monday, followed by much cooler weather through the middle of next week. && .NEAR TERM /UNTIL 6 AM SUNDAY MORNING/... 01Z surface analysis places backdoor cold front just south of KFIG/KUNV/KSEG. All near term models have the front sagging into the southern counties after midnight and reaching all but perhaps Somerset Co by dawn. Expect readings to fall to into the low and mid 40s over much of the forecast area by dawn, with readings as low as freezing over the northern tier and staying as mild as the upper 50s over Somerset Co. The best chance of precip tonight will likely come this evening over the northwest mountains in association with a dying low level jet and plume of higher PWATS. Based on radar trends and HRRR will maintain likely POPS along the NY border, with rapidly diminishing chance of precip further south. Although any rain will be very light, have kept the chance of a bit of freezing rain overnight along the NY border, where temps will likely dip into the low 30s. Penndot road temps still running in the low 50s at 01Z despite air temps in the low to mid 30s. Therefore, not anticipating the need for a winter wx advisory. For the bulk of central Pa, the main story tonight will be the arrival of much cooler air behind the front, with little chance of precip. Model soundings do indicate the potential of some patchy drizzle developing toward dawn, as moist and much cooler easterly flow ascends the higher terrain of central Pa. && .SHORT TERM /6 AM SUNDAY MORNING THROUGH 6 PM SUNDAY/... Temps will warm up just enough early Sunday to diminish the threat for icy precip, however the recent late spring warmth will be a memory, as the back door front remains south of the area and we stay rather cloudy and damp with patchy drizzle. The patchy drizzle will likely give way to a steadier rain by evening, as anomalous southerly low level jet and plume of higher PWATS arrive ahead of approaching upper low, overrunning dome of cool/stable air over central Pa. Based on an expectation of overcast skies all day, and upstream temperatures north of front, have trended max temperatures downward Sunday closer to those of the 12Z HREFV2 and 18Z NAM. Highs Sunday could be close to 40 degrees cooler than today, ranging from the low and mid 40s over most of the area, to perhaps near 60F over southwest Somerset Co. && .LONG TERM /SUNDAY NIGHT THROUGH SATURDAY/... The highest impact weather for the forecast period will occur beginning on Sunday afternoon and continuing into Monday morning. Models are in good agreement in ejecting a potent upper low through the eastern Great Lakes early next week. The associated negatively tilted upper shortwave trough and surface front are made to swing through Sunday night and early Monday. The GEFS shows a 5-6 sigma (50-60kt) SSE low level jet surging through the area Sunday night. The deep moisture is forecast to originate over the southern Gulf of Mexico/western Caribbean resulting in PWATs surging to between 1-1.5 inches, or some 2-4 std dev above normal. The GEFS shows a high probability of 24 hour rainfalls in excess of 2 inches over much of central PA, and at least a 1 in 3 chance of rainfall greater than 3 inches. It`s still too early to be specific about exact areas so watches are not being considered yet, but if the trends for a heavy rain even for central PA keep being advertised over the next day or so, Flood Watches will become a distinct possibility. Before this happens, Sunday looks to be a transition day. A back door cold front will have settled south through at least the northern 2/3 of the CWA bringing to an end the brief romance we will have shared with Spring-like warmth. At this time leaned toward the warmer ensemble blended numbers which keep lows well above freezing, supporting just a plain rain forecast rather than any complicating factors from freezing rain or sleet. On the back side of the strong front, we will see yet another return to colder than normal weather and even a couple of opportunities for snow showers. The first chance for snow showers will be Monday night and early Tuesday as the upper low swings through to our north. Another system may bring more snow showers Wednesday night into Thursday. We don`t expect any significant accumulations, but as we enter mid April, the prospects for snow are less than welcome. Past Thursday we foresee a break of dry weather into early next weekend as energy reloads over the southwestern U.S. allowing weak upper ridging to build over the eastern part of the country. && .AVIATION /03Z SUNDAY THROUGH THURSDAY/... Updated all the TAFS as of 1030 PM, mainly backed off on the gusty winds and lower conditions with the showers. Other than UNV, not much in the way of wind now. Band of showers to the west falling apart. Earlier discussion below. 00Z TAFS a combination of guidance and trends on obs and radar. Cold front moved south of the office here just after 7 PM. Temperatures down 15 degrees since I came in. A few showers overnight across the north and west. The main issue will be lower conditions later tonight into Monday, as colder air works in. Showers will become more widespread again later Sunday into Monday, along with gusty winds. Outlook... Mon...Rain will taper to showers W to E; Low ceilings likely western 1/3 with improving conditions central/east. Rain/snow showers possible western 1/3 Mon night. Tue...Low ceilings likely western 1/3 with lingering rain/snow showers. VFR elsewhere. Wed-Thu...Chance of rain/snow showers with sub VFR mainly over western and northern terminals. && .HYDROLOGY... Heavy rainfall of 1.5 to 3 inches is probable Sunday night into Monday and will result in significant rises on area rivers and streams. Small streams will likely see rapid rises with minor to moderate flooding possible. There is also the potential for localized short duration flooding especially in urban corridors and poor drainage areas. Heaviest rain across the far east could be more like late Monday. Still some model spread. && .CLIMATE... New record high set at Williamsport on 4/13 of 85 degrees. Previous record was 84 degrees in 1977. New record high set at Altoona on 4/13 of 85 degrees. Previous record was 84 degrees in 1971. Record highs at select sites for April 14th: Harrisburg-89 in 1941 State College-82 in 1960 Williamsport-84 in 1960 Altoona-80 in 1968 The high today in Altoona was 87. This is a new record for Altoona. && .CTP WATCHES/WARNINGS/ADVISORIES... None. && $$ SYNOPSIS...Fitzgerald/La Corte NEAR TERM...Fitzgerald SHORT TERM...Fitzgerald/La Corte LONG TERM...La Corte/Gartner AVIATION...Martin HYDROLOGY...Steinbugl/Martin CLIMATE...Steinbugl/Martin
Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
1048 PM EDT Sat Apr 14 2018 .UPDATE... A quick update as the forecast remains on track and all warnings and advisories remain in effect. The bifurcation of the warm conveyor associated with the mature low pressure system moving into the Midwest produced a mid level dry pocket over Lower Michigan. This led to drizzle and freezing drizzle over SE Michigan that was mostly on the light side based on surface observations. Meanwhile, surface temperatures continue to settle farther below freezing, especially along and north of I-69 where upper 20s are common during late evening. The cooling process has beens surprisingly slow toward metro Detroit since sunset given the strong NE wind. Surface temperature analysis just does not show much cold advection occurring there. Instead expect a slow leak southward toward the I-94 corridor overnight before the next round of heavy precipitation moves into the area. That activity is on track to expand northward from southern Illinois and the Ohio Valley judging by radar composite and rapid update models. When it does arrive, the warning area will be primed for freezing rain and a period of heavy icing for a few hours. Model soundings also show the surface based cold air deep enough for heavy sleet as well, especially toward the Tri Cities and northern Thumb. Upcoming forecast updates will track the surface temperature response to the low pressure system moving toward Toledo during the morning. This should allow temperatures to warm above freezing during early to mid morning as far north as the M-59 corridor and possibly the I-69 corridor toward noon. && .PREV DISCUSSION... Issued at 823 PM EDT Sat Apr 14 2018 AVIATION... Conditions across SE Michigan during the evening will waver between IFR in stratus and heavier drizzle/freezing drizzle and MVFR with lighter drizzle and freezing drizzle. A few rain/freezing rain showers are also possible in between but the vast majority of the evening will feature low precipitation rates. Strong NE wind will not waver however and will continue to drive sub freezing air farther south toward the Ohio border and upper 20s air farther south through FNT and PTK. This will set the stage for substantial amounts of freezing rain and sleet as the next wave of high rate precipitation moves in from the south overnight. The center of low pressure moving toward Toledo during Sunday morning will help nudge temperatures above freezing first at DTW but taking until late morning/early afternoon at MBS. For DTW... Temperature will settle toward the freezing mark during the evening and then hover between 30-32 overnight. This will make intermittent freezing drizzle possible before a heavier rain showers and freezing rain move in overnight. Temperature is expected to rise above freezing around 12Z Sunday morning. Both precipitation and low ceiling will contribute to IFR overnight through Sunday followed by LIFR as the surface low moves very near DTW late in the day. /DTW THRESHOLD PROBABILITIES... * High for ceiling 5000 ft or less tonight through Sunday. * Low for ceiling 200 ft or less. * Low in precip type as FZDZ through 04Z tonight. Medium for ptype of FZRA from 04-12Z. PREV DISCUSSION... Issued at 445 PM EDT Sat Apr 14 2018 Initial moisture push up the warm frontal slope and into the elongated mid-level deformation axis over the Great Lakes and New England is in the process of pushing east coincident with exiting mid-level forcing. During this first round of precip, 2m temperatures have fallen below freezing down to I-69 with upper 20s in the Saginaw Valley. Cold air is indeed surviving the trip across Lake Huron as noted by low 20s temps over much of Northern Lower. The coincidental timing of sunset and the exit of heavier precip will allow cold and dry advection to take over for the remainder of the evening. Temperatures are forecast to fall below freezing down to I-96/696 by sunset, followed by the southern extent of the Irish Hills in Washtenaw and Monroe and finally the urban corridor by midnight or earlier. Strong northeast wind funneling through Saginaw Bay will continue to produce damaging winds in Bay County and adjacent areas for the next 6 to 10 hours before veering of the wind field allows the speed of the incoming marine winds to diminish. Advisory criteria wind will continue to be possible in the other Saginaw Valley counties and Huron County during this time as well. Reports of winter impacts have been sparse so far today. As noted earlier, the initial mid-level cold push weakened the inversion considerably leading to predominantly snow pellets and sleet. Some icing of power lines and roads was reported in the vicinity of Frankenmuth, however. The probability of sleet will now steadily diminish for the remainder of the event. For this afternoon and the first half of tonight, this will occur to due to the encroachment of the upper ridge axis fracturing the precipitation shield and scouring out mid-level moisture. Strong northeast wind beneath an inversion of this strength should produce widespread drizzle and freezing drizzle, potentially until the next surge of moisture arrives Sunday morning. So long as drizzle reaches the ground, ongoing dry advection will only make matters worse by increasing accretion efficiency during this relative lull in QPF. Motorists should expect slick roads as early as this evening regardless of rain intensity. The latest guidance continues the trend of an aggressive southward push of cold air tonight, supported by the observations of very cold air that has already made it into APX`s area. A southward adjustment to the freezing line has warranted an expansion of the freezing rain area to include Macomb County for a longer period of time (upgraded to a warning) and Lenawee County, where the advisory has been extended south. The latter is primarily for the higher elevations of the Irish Hills. Uncertainty is greatest near the Ohio border, but after observing the quick ice-up invof Frankenmuth this morning in a much less favorable scenario, will take no chances. The next round of widespread heavy precip is modeled to arrive late tonight and last well into Sunday. This precip shield is currently in its formative stages over the Mississippi River valley. Showers are blossoming over the Missouri and Illinois in response to increasing fgen/convergence in advance of the dry air stream noted on WV. In addition, echoes are now increasing over eastern Louisiana and Arkansas the warm conveyor begins to ramp up in the wake of ongoing convection in the Deep South. A confluence of these forcings is modeled to occur as they lift into the CWA Sunday morning. It is therefore critical to note that the 12z NMM, ARW, and recent runs of the HRRR actually maintain two separate separate QPF maxima, casting maximum uncertainty through the heart of the forecast area. With no other options, maintained a compromise for QPF with some room to adjust up and a lot of room to adjust down. The potential for embedded convective elements precludes being too conservative at this time. Freezing rain will end from south to north through the day Sunday with total ice accretion forecast to range from 0.1 in the hills of Lenawee County to 0.3" north of M59 to 0.5" north of the I-69 corridor. The large low pressure system will finally lift away towards the New England region Tuesday bringing much drier conditions to the Great Lakes region. Northwest winds behind the departing low will continue to bring cooler air as highs on Tuesday only get up to around 40. However, upper level ridging and surface high pressure do build in over the area for the middle of the week. This will allow temps to moderate slightly on southwest winds. The good news is the rest of the extended forecast going into the start of the weekend looks to have temps remaining in the upper 40s to lower 50s. Although, temps warm up slightly over the week, precipitation chances look to increase as well. Currently, a weaker low looks to move across the Great Lakes region beginning late Wednesday through early Friday. MARINE... A strong northeast gale over Lake Huron gusted to storms or near- storms in inner Saginaw Bay for much of the day. Wind in the bay will gradually decrease overnight as wind veers to easterly. However...the gradient will remain quite strong over the lakes and sustained easterly gales will continue through Sunday. Gusts to storms will again be possible over portions of the central open waters. Significant wave heights over the open waters will range from to 10 to 15 feet over the next 24 hours with maximum wave heights approaching 25 feet over west-central portions of the basin. Hazardous wave conditions will likewise persist in the nearshore zones...especially near the tip of the Thumb...until late Sunday night. HYDROLOGY... Conditions will remain wet through the rest of this weekend as a low pressure system makes its way the Great Lakes. The first round of precipitation is beginning to move east of the area, which resulted in areas of freezing rain from Flint northward. There will be somewhat of a lull in precipitation after this first round moves out with the potential for some drizzle conditions before the next round of rainfall. Freezing rain and or sleet will most likely be to form of precipitation overnight as the next round of widespread arrives after sunset with temperatures reach freezing or below. The higher ice accumulations remain north of M-59 where icy conditions have already occurred. Once morning arrives and temperatures warm back up above freezing, freezing rain will transition back to rain. An additional 1 to 2 inches of rainfall is forecast for southeast Michigan through the rest of the weekend. In addition to the precipitation, strong northeast winds are causing lakeshore flooding off of Saginaw Bay into portions of Bay and Tuscola County. Wayne, Macomb, and Monroe County will also be affected by these northeasterly winds and experience lakeshore flooding off of Lake St. Clair and Lake Erie. Lakeshore Flood Warnings and Advisory are in effect for these counties into tomorrow. && .DTX WATCHES/WARNINGS/ADVISORIES... MI...Winter Weather Advisory until noon EDT Sunday for MIZ075-076-082. Winter Storm Warning until noon EDT Sunday for MIZ047>049-053>055- 060>063-068>070. Lakeshore Flood Warning until 8 AM EDT Sunday for MIZ048-054. Lakeshore Flood Warning until 4 PM EDT Sunday for MIZ076-083. Lakeshore Flood Advisory until 8 AM EDT Sunday for MIZ070. Lake Huron...Gale Warning until 10 PM EDT Sunday for LHZ361>363-462. Gale Warning until 4 PM EDT Sunday for LHZ421-422-441-442-463. Small Craft Advisory until 5 AM EDT Monday for LHZ443. Lake St Clair...Small Craft Advisory until 4 PM EDT Sunday for LCZ460. Michigan waters of Lake Erie...Small Craft Advisory until 4 PM EDT Sunday for LEZ444. && $$ UPDATE.......BT AVIATION.....BT DISCUSSION...JVC/SP MARINE.......JVC HYDROLOGY....AA You can obtain your latest National Weather Service forecasts online at
Area Forecast Discussion
National Weather Service Grand Rapids MI
800 PM EDT Sat Apr 14 2018 LATEST UPDATE... Aviation .SYNOPSIS... Issued at 330 PM EDT Sat Apr 14 2018 A major winter storm will bring mixed precipitation and windy conditions tonight into Sunday. Many areas will see significant impacts from icing due to freezing rain and sleet and windy conditions. Temperatures will remain unseasonably cold through early next week. && .SHORT TERM...(This evening through Monday night) Issued at 330 PM EDT Sat Apr 14 2018 At 1845Z KGRR radar trends/sfc obs indicate a mix of freezing drizzle/light freezing rain and sleet near to north of I-96 with mainly rain south of I-96. This light precipitation will continue late this afternoon and early evening and we expect pcpn to transition to light freezing rain over our southern counties this evening as sfc temps fall slowly to the freezing mark. ENE winds will continue to gust to around 30-40 kts late this afternoon into the evening. Some power outages are likely to continue to occur late this aftn and early evening especially near to nw of KGRR where higher res guidance such as the hrrr and 3km nam show potential for highest gusts with isolated gusts to 45 to 50 kts possible. Concerns are increasing for significant freezing rain to develop tonight a little further south into Allegan and Barry counties and also along the I-94 corridor. A steady period of freezing rain is expected to develop there late this evening and overnight. For this reason we decided to upgrade Allegan/Barry counties to a winter storm warning since it now appears a good portion of those counties will receive around a quarter to potentially around four tenths of an inch of ice accumulation overnight. Impactful freezing rain is also likely to develop along the I-94 corridor late this evening and overnight as suggested by a consensus of latest higher resolution short range guidance and fcst soundings. Up to around a quarter of an inch of ice accumulation is possible especially over northern portions of Calhoun and Jackson counties. However pcpn there will transition back to liquid form by mid morning Sunday when sfc temps will moderate back up into the mid 30`s. Conditions will deteriorate along the I-96 corridor Sunday morning as precipitation there will transition from sleet to freezing rain as predominant pcpn type. It may take until around midday for sfc temps to climb to above freezing there given the continued brisk ne winds. Further north a mix of sleet and freezing rain will linger into the early afternoon hours Sunday before the steadier batch of pcpn moves out as a dry slot works in. Impacts from this storm system will include numerous to potentially widespread power outages tonight into Sunday due to the combination of strong winds freezing rain and sleet. Scattered power outages have already occurred due primarily to the strong wind gusts this aftn. Lighter mixed pcpn will still linger through Sunday night into Monday but with little if any additional impacts. West winds will ramp up Monday and the caa will cause any mixed pcpn to change to some light snow before pcpn finally tapers off. .LONG TERM...(Tuesday through Saturday) Issued at 330 PM EDT Sat Apr 14 2018 The slower departure of our current system results in lingering clouds and a small chance of light rain and snow showers lasting into at least Tuesday morning. The low level cyclonic flow and cold advection on the back side of the system actually lingers through 00Z Wednesday, which in prior guidance was a period in which sfc ridging was supposed to prevail. The ridging and associated clearing and dry wx is now only a brief period on Tuesday night as the next system will already be fast approaching from the Plains on Wednesday. Once again precipitation type is tricky with the system for Wednesday into Thursday. Models offer differing solutions on the track and timing of sfc low and thermal profiles. Consensus solution at this point is for precip to be a rain/snow mixture to start (if it arrives in the morning), changing to mostly rain for Wednesday afternoon, then going back to rain and snow Wednesday night - possibly even to all snow north of I-96 and lasting into Thursday morning. Some wet snow accumulations seem possible north of I-96 in the cooler nighttime/early morning period of Wed ngt/Thurs, especially if the ECMWF solution of a potent looking closed mid level circulation tracking east through srn Lwr MI is correct. Things turn more tranquil behind the departing Thursday system, with a moderating trend in temps. Current medium range guidance actually indicates we could have a very pleasant (and well deserved) spring weather pattern for next weekend as a surface ridge becomes parked over the state. This would translate into some sunshine, light winds and highs up near 60 degrees - which is closer to normal. && .AVIATION...(For the 00Z TAFS through 00Z Sunday evening) Issued at 800 PM EDT Sat Apr 14 2018 IFR conditions will become widespread overnight as ceilings lower blo 1000 feet AGL and freezing rain and sleet redevelops by 06Z. LIFR is possible late tonight into Sunday morning then conditions should improve to MVFR during the afternoon. East winds will gust over 30 knots though tonight before decreasing by Sunday afternoon. && .MARINE... Issued at 330 PM EDT Sat Apr 14 2018 The gale warning remains in effect through early Sunday evening. && .HYDROLOGY... Issued at 200 PM EDT Sat Apr 14 2018 As precipitation continues across the region, river levels are around normal but rising. Precipitation totals will range from over an inch and a half to around three inches through Sunday night. This could lead to river flooding, but at this time only the Portage River near Vicksburg is forecast to go above flood stage. Stay tuned, as more flood warnings may be on the way if all of the precipitation is realized. && .GRR WATCHES/WARNINGS/ADVISORIES... MI...Winter Storm Warning until noon EDT Sunday for MIZ037>040- 043>046-050>052-056>059-064>067. Winter Weather Advisory until noon EDT Sunday for MIZ071>074. LM...Gale Warning until 8 PM EDT Sunday for LMZ844>849. && $$ SYNOPSIS...Laurens SHORT TERM...Laurens LONG TERM...Meade AVIATION...Ostuno HYDROLOGY...63 MARINE...Laurens
Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
1039 PM EDT Sat Apr 14 2018 .SYNOPSIS... A vigorous cold front will move through the area Sunday bringing showers and thunderstorms, some of which could be severe with damaging wind, hail, and isolated tornadoes. Much cooler air will overspread the region in the wake of the front on Monday with temperatures warming again through midweek. && .NEAR TERM /THROUGH SUNDAY/... As of 1030 PM: Very little change to the existing forecast was needed for the overnight hours, mainly a minor downward adjustment to temperatures across the northern tier where the clouds have been fairly thin this evening. Otherwise, water vapor imagery continues to depict the center of the strong, closed upper system spinning eastward over the MO/IA border late this evening, with the associated vigorous surface cold front extending southward through western TN into MS. Deep moisture ahead of the front, along with lingering instability in the rich low level theta E air across the Deep South, are regenerating convection across mainly AL and the FL pandhandle late this evening, with this activity forecast to move slowly east as the upper system increases the negative tilt. Meanwhile, closer to home, a high-elevation Wind Advisory has been posted overnight through Sunday morning across the southwestern NC mountains. The 850 mb flow on the RAP continues to trend up with plenty of 50 to 60 kt winds expected during the peak of the pre- frontal warm advection, with some mixing/channeling of the better winds as showers begin to arrive late tonight. Windy conditions will also be possible down in the valleys, and farther north along the mountain chain, but probably with sub-advisory gusts. All attention will then turn to Sunday, as robust shear profiles and gradually improving instability will cross the region just ahead of the sharp cold front. The 18Z NAM has trended up on instability along/near the I-77 corridor for Sunday afternoon, with sbCAPE values now above 2000 J/kg, but this is an outlier compared to the approximately 400-600 J/kg values on the ECM/GFS/GEFS mean for 18Z. Regardless, shear will be tremendous with backed low-level flow, 50+ kt of sfc to 3 km bulk shear and 60+ kt in the sfc-6km layer. The current Day 2 outlook Marginal west and Slight east still look well- placed. Wind and tornadoes will be the primary threats, especially for the eastern half of our area Sunday afternoon. Still anticipate that localized flooding will be possible given the high precipitable water values (2 to 3 standard deviations above normal) and the efficient, heavy rain producing showers and thunderstorms expected. However, given the limited duration of the event on Sunday, training of cells will be the primary player in any flash flooding and any Watches would necessarily have to cover the entire region. Given the short duration and drier antecedent conditions, will hold off on any Flash Flood Watches at present, but short-fused hydro products remain possible. && .SHORT TERM /SUNDAY NIGHT THROUGH TUESDAY/... As of 230 PM Saturday...The large upper low will drift east across the Great Lakes, allowing heights to rise atop the CWFA thru the short term. The associated sfc low will push its trailing cold front east of the area overnight Sunday night, taking the convective into central NC. Some wrap-around moisture will bump up against the TN/NC border thru Monday aftn, producing scattered showers. Strong 850 mb CAA will bring snow levels down to about 3500 ft by early Monday morning. Snow accums should be light, with 1-2" possible in the highest elevations before the showers taper off. Temps will drop into the 30s in the mountains Sunday night and 40s piedmont. Then with continued low-level CAA, temps warm only into the 40s to lower 50s in the mountains and upper 50s to lower 60s piedmont Monday with breezy conditions. Monday night looks the coldest night of the week with temps dipping into the 20s to mid 30s in the high terrain. A freeze warning may be needed across the mountains where the growing season has started (all but the Northern Mountains). Conditions don`t look ideal for frost, but nevertheless some mid 30s will be possible across the NC foothills and NW piedmont. Temps rebound nicely on Tuesday as mild high pressure settles in from the west. Highs slightly below normal in the mountains and near normal east. && .LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/... As of 230 PM Saturday: The medium range forecast begins Tuesday night as the forecast period is expected to be an overall quiet one. With sfc high pressure in place across the Southeast and an exiting upper trough well north of the FA, latest guidance continues to prog the eastward progression of a low amplitude upper ridge across the central US Tuesday night into Wednesday as the system behind it tracks across the central Plains and into the OH Valley Wednesday night. With nearly zonal flow aloft and a limited supply of moisture, a trailing cold front from this system will push through the FA from west to east Wednesday night into Thursday morning. Expect the development of any isolated showers to remain confined to areas along the TN border as the Upstate and NW Piedmont will remain dry with passing clouds and breezy winds. In fact, ahead of the front on Wednesday through into Thursday evening, do expect breezy winds across the entire FA with a tightening pressure gradient. Behind the front, the upper trough associated with this system is expected to push eastward across New England Thursday night into Friday with sfc high pressure returning to the region for the end of the week. Another weak upper ridge is progged to build across the central US ahead of the next developing system across the Rockies. Wednesday will be the warmest day of the rest of the week, with temperatures in the upper 70s/around 80 degrees across the NW Piedmont and Upstate, and slightly cooler back across the mountains. The coldest night/morning will be Thursday night into Friday morning behind the recently passed cold front with temperatures across the mountains in the 30s/lower 40s - mid to upper 40s elsewhere. Otherwise, the warmer trend will continue through into Saturday, with temperatures at or just above normal. && .AVIATION /03Z SUNDAY THROUGH THURSDAY/... At KCLT and elsewhere: Lowering VFR cigs will be the rule through the late evening and very early overnight hours as the deep frontal moisture gradually approaches from the west. Guidance is in relatively good agreement that lowering MVFR cigs will become IFR in most areas before daybreak, with some flavor of IFR to low end MVFR at best expected with the improving shower and thunderstorm coverage through Sunday. Will time thunder to mainly the late morning through mid-afternoon period across the mountain/foothill TAF sites, but feature mainly post-19Z timing at KCLT - where thunderstorms will likely be stronger. Robust southerly wind gusts will develop through the day and short-fused timing of thunderstorm gusts will likely be needed as the convective lines approach the airfields on Sunday. Widespread MVFR to occasionally IFR visibilities are expected under the torrential downpours with the peak convection. Sunday will be a rough day for aviation interests around the region. Anticipate winds turning southwesterly late in the period with fropa and NW and windy at KAVL, with gradual drying lifting cigs to MVFR or possibly VFR very late. Outlook: Other than perhaps some lingering mountain showers, dry and cooler conditions should return Monday and continue into mid week. A drier cold front may arrive late in the week from the northwest. Confidence Table... 02-08Z 08-14Z 14-20Z 20-00Z KCLT High 93% High 87% Med 67% High 88% KGSP High 100% High 91% Med 65% Med 71% KAVL High 93% Med 73% Med 75% Med 67% KHKY High 100% High 83% Med 78% High 86% KGMU High 100% High 89% Med 64% Med 75% KAND High 98% Med 73% Med 63% Med 74% The percentage reflects the number of guidance members agreeing with the scheduled TAF issuance flight rule category. Complete hourly experimental aviation forecast consistency tables and ensemble forecasts are available at the following link: && .GSP WATCHES/WARNINGS/ADVISORIES... GA...None. NC...Wind Advisory until noon EDT Sunday for NCZ051-052-058-059- 062>064. SC...None. && $$ SYNOPSIS...Carroll NEAR TERM...HG SHORT TERM...ARK LONG TERM...SGL AVIATION...HG
Area Forecast Discussion
National Weather Service Lincoln IL
1101 PM CDT Sat Apr 14 2018 .UPDATE... Issued at 850 PM CDT Sat Apr 14 2018 Cold front has edged into extreme east and southeast Illinois this evening accompanied by a band of showers, which extends further west to along and east of a Peoria to Springfield line. Short term guidance suggests another wave of rain will move north out of southern Illinois and affect about the eastern half of the forecast area overnight. Further west, the large and deep upper low now centered over southern Iowa will shift slowly into our area by tomorrow evening bringing unseasonably cool weather to the area and another round of showers, especially tomorrow afternoon across our north and west, as the very cold temperatures aloft associated with 500 mb low move across the region. By late tomorrow afternoon and especially tomorrow night, the rain will mix with and then become mainly scattered snow showers overnight accompanied by a gusty northwest wind and temperatures dropping into the mid 20s north to around the freezing mark far southeast IL. Made some adjustments to the precipitation trends for the overnight hours, especially across the east. We should have the updated zones out by 915 pm. && .SHORT TERM...(This evening through Sunday) ISSUED AT 219 PM CDT Sat Apr 14 2018 Early afternoon surface map showed low pressure near Springfield, with a cold front extending south and the oscillating warm front east to near Champaign. Showers have been ramping up quite a bit over western Illinois to as far east as Peoria and Springfield. Eastern CWA is currently dry. SPC mesoanalysis shows surface instability has been limited so far, despite some thinning of the clouds that occurred earlier in eastern Illinois. However, RAP guidance shows potential for 500-1000 J/kg of surface CAPE by late afternoon in areas east of I-57. Have kept a mention of isolated/scattered thunder ahead of the low/cold front, which should be near Champaign by 7 pm. Widespread showers expected overnight, as the large upper low in northeast Nebraska moves east, and a new surface low reforms across the Tennessee Valley. The eastern CWA will be most impacted by the rain, as the west comes under the influence of the dry slot currently in western Missouri. However, as the upper low drifts into western Illinois toward midday Sunday, the showers will be on the increase again. .LONG TERM...(Sunday night through Saturday) ISSUED AT 219 PM CDT Sat Apr 14 2018 Looks like the 3rd Sunday in a row with some snow potential across the CWA, as colder air is drawn in behind the departing upper low. Rain to snow changeover may begin in the far northwest CWA as early as late afternoon, but a more rapid changeover is expected in the evening. Only a minor dusting is currently expected, mainly north of I-74. Given the first Sunday with snow was on Easter, here`s hoping the myth of "7 Sundays of rain after an Easter rain" doesn`t apply to snow as well. Freeze potential still looks strong for Sunday and Monday nights, with most of the CWA dropping into the 20s. Right now, the growing season is considered advanced enough to warrant frost/freeze headlines south of I-70, though areas to the north likely had some planting done over the recent warm spell. With the southeast CWA a bit more uncertain with freezing conditions, will hold off on any headlines for now. Not a lot of change in the forecast the remainder of the week. The midweek storm system still looks to largely track north of us, though the GFS hints at some light precipitation with the trailing cold front on Wednesday. Right now, will limit any PoP mention to the northern CWA closer to the low track. Late in the week, another strong system will take shape over the central Plains. The GFS is much quicker with this system, bringing rain into the area as early as midday Saturday. However, the ECMWF is about 18-24 hours slower. Will keep PoP`s on the lower side (around 30 percent) at this point and will watch things shake out over the next several runs. && .AVIATION...(For the 06Z TAFS through 06Z Sunday night) Issued at 1100 PM CDT Sat Apr 14 2018 A large weather system to our west will continue to edge slowly towards our area over the next 24 hours. Mainly MVFR with occasional IFR and LIFR conditions expected as the system moves across our area with the lower cigs and vsbys across our north. An area of showers continues to affect our central and eastern TAF sites late this evening with another wave of rain moving north into at least the I-57 corridor with some models suggesting the rain may occur further west late tonight into Sunday morning. We should see a break in the precip for a brief time Sunday morning before scattered rain showers move across parts of our area, again favoring PIA and BMI with more widely scattered coverage further south. West to northwest winds of 8 to 13 kts tonight will be more westerly on Sunday with speeds increasing to 12 to 17 kts by late morning with gusts up to 25 kts at times in the afternoon. && .ILX WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...Smith SHORT TERM...Geelhart LONG TERM...Geelhart AVIATION...Smith
Area Forecast Discussion
National Weather Service Indianapolis IN
1146 PM EDT Sat Apr 14 2018 .UPDATE... The AVIATION Section has been updated below. && .SYNOPSIS... Issued at 237 PM EDT Sat Apr 14 2018 A low pressure system will affect the area into Monday. In the wake of this system, high pressure will build in for Tuesday. Another low pressure may affect the area towards the middle of next week. && .NEAR TERM /Overnight/... Issued at 1019 PM EDT Sat Apr 14 2018 Rain and convection has blossomed over the last hour or so as moisture begins to interact with the southward moving warm front and as a low level jet noses into the region from the south. The presence of the warm front has led to a sharp temperature gradient across the forecast area this evening...ranging from the lower and mid 40s far north to mid 60s south as of 02Z. The overall forecast is in good shape this evening. The main adjustments focus on fine tuning precip timing over the next few hours and trying to provide a bit more detail to temperatures. It has been fascinating to watch the abrupt temperature changes either side of the warm front as it has progressed slowly south all evening. Since about 00Z...the boundary has been located over the Indy metro as its southward push slows. As of 02Z...the boundary appears to essentially bisect the forecast area from west to east...passing through the southern Indy metro just a few scant miles south of KIND and the NWS office here in Indy. Hi-res guidance continues to suggest that the boundary is not likely to push much further south before retreating a bit back north overnight as the surface wave moves into the region from the west. This has created a tricky wind and temperature forecast for the next several hours in the vicinity of the boundary...and have utilized HRRR as a starting point with subtle tweaks based on current obs. As for the rain...development has been a bit slower than previously thought but precipitation coverage is beginning to blossom in response to the moisture being drawn north by the low level jet. Expect widespread rain overnight with the potential for a few embedded lightning strikes. Categorical pops remain warranted. Patchy fog has also developed over northeast counties this evening. Expect some improvement in visibilities as rain expands into the area. Zone and grid updates out. && .SHORT TERM /Sunday through Tuesday/... Issued at 237 PM EDT Sat Apr 14 2018 Model guidance suggests cold front will be pushing through the eastern zones by sunrise Sunday, exiting the forecast area by the late morning hours. Will keep high PoPs going over the eastern zones for Sunday morning until frontal passage. Otherwise, will keep some chance PoPs for light showers going into the day Monday, coinciding with the passage of the upper trough. Lowering thicknesses and a cooling boundary layer suggests some mixed precipitation is possible Sunday night into Monday morning, but accumulations are not expected. Dry weather expected for Monday night and Tuesday, as a surface ridge drifts over the area. Progged low level thicknesses suggest the GFS MOS temperature guidance for the next couple of days is probably too warm. Will cut the guidance by about 3-6 degrees in each period. && .LONG TERM /Tuesday night through Saturday/... Issued at 312 PM EDT Sat Apr 14 2018 Main focus for the long term will be on timing of showers and also temperatures. Models in decent agreement that low pressure system will bring rain shower chances to central Indiana for the middle of next week and next Saturday. Otherwise, high pressure will bring dry weather to the area. Confidence in trends is good but in shower coverage and exact timing is not. So, will not make any changes from the forecast builder output. Confidence in temperature trends is good with near to above normal temperatures on Wednesday followed by colder than normal temperatures in the wake of the first frontal system the remainder of next work week. Temperature may get close to normal again next weekend but confidence in timing is not as good with the model and ensemble member spread large. && .AVIATION /Discussion for 150600Z TAF Issuance/... Issued at 1146 PM EDT Sat Apr 14 2018 IFR conditions expected at times overnight into Sunday morning with improvements Sunday afternoon. Rain continues to increase in coverage late this evening as low pressure over western Illinois approaches the region. A warm front extending east into central Indiana from the low has also served as a focal point for showers. The frontal boundary remains stalled just south of KIND and as the low likely to retreat back north a bit. This will cause a bit of a chaotic wind direction forecast for the first few hours of the forecast...particularly at KIND. This will veer winds back to a southeast direction at KIND around or shortly after 06Z before shifting to westerly as the occluded boundary arrives from the west. Ceilings and visibilities will slip to IFR levels overnight with the rain and expect this to linger through mid morning. The widespread rain will shift east of the terminals with the low pressure by midday with ceilings recovering to MVFR levels. A few showers may redevelop Sunday afternoon then continue into Sunday evening as the trailing upper level low arrives. Winds will back to southwest Sunday morning then back to westerly at all terminals by Sunday evening. && .IND WATCHES/WARNINGS/ADVISORIES...NONE. && $$ SYNOPSIS...JAS NEAR TERM...Ryan SHORT TERM...JAS LONG TERM....MK AVIATION...Ryan
National Weather Service Jackson KY
1151 PM EDT Sat Apr 14 2018 .UPDATE... Issued at 1150 PM EDT SAT APR 14 2018 Pops were adjusted based on recent radar trends and HRRR runs. This slowed down the increase in pops beyond the first two or three tiers of counties down through 2 to 4 AM, before bringing higher pops east. Measurable rainfall seems like a certainty at this point for Sunday morning so pops were raised to 100 percent. Otherwise, no significant changes were made at this time. UPDATE Issued at 850 PM EDT SAT APR 14 2018 Hourly grids of temperature, dewpoint, and wind have been updated based on recent observations. In addition, pops were adjusted up slightly a bit further east near the JKL vicinity to account for recent radar trends. A prefrontal trough/outflow boundary moved east across the region during the afternoon and early evening and has now moved into WV over the past couple of hours. This led to a couple hours of west winds, though winds are now southeast to south across western sections in advance of an approaching cold front. Showers continue to be be mainly over western sections of the area with radar trends and convective allowing models such as the HRRR taking the current area of showers across JKL and points to the north with a lull across that area to follow. Far eastern sections of the region may not measure until closer to sunrise when the front nears. && .SHORT TERM...(This evening through Sunday night) Issued at 300 PM EDT SAT APR 14 2018 The focus in the short remains the potential for showers and storms through early Sunday morning and the possibility of locally heavy rainfall. The latest model data is suggesting the best chance for widespread rain across eastern Kentucky will be from late tonight through the day on Sunday as a cold front moves across the area. Based on current trends, any rain we experience the rest of today through early tonight is going to meager. A line of showers and storms that moved across western and central Kentucky early today has fizzled out quite a bit as it has entered the western part of our forecast area. The latest trends in radar data, available obs and short term model suggest that this trend of garden variety rainfall and scattered showers will continue this afternoon. The showers will likely become a bit more widespread as evening approaches, and an isolated thunderstorm cannot be ruled out, but rainfall amounts in general should not lead to any issues across the area. That all being said, the storm total rainfall for this event was decreased slightly again, based on the already mentioned trends and the latest model QPF forecasts. Temperatures are expected to stay above normal today and tonight, before cooling off a bit on Sunday after a cold front moves through. Tonights lows should only fall into the upper 50s to lower 60s across the area. Highs on Sunday should be close to or slightly below normal across the area. As colder air filters into the area Sunday night behind the departed front, it may cool off enough to allow some snow to mix with rain as the precip begins to exit the area. There may even be a few spots that see a brief period of all snow. Little if any snow accumulation is expected. .LONG TERM...(Monday through Saturday) Issued at 450 PM EDT SAT APR 14 2018 The models are in only somewhat better agreement aloft today for the long term portion of the forecast. They all depict the deep closed low lifting northeast and out of the area Monday with good agreement. In the wake of this, heights will rise over eastern Kentucky as a ridge starts to move east from the High Plains on Tuesday. This is where the model spread significantly increases with the handling of the next trough moving through the Northern Rockies and the downstream effects. The large difference between the GFS and ECMWF remain the troubling aspect of the forecast at mid range with the GFS taking its low center east much quicker than the ECMWF - with some support from the Canadian. The ECMWF`s slow, but not deeper, solution brings its closed low to the Northern Ohio Valley by Thursday morning or about 12 hours behind the others. This makes for a compromised solution with much lower confidence than usual. These differences mitigate themselves in time, though, with the week ending with a similar pattern aloft locally as the trough pulls away to the east. Ridging then pushes into the area from the Plains by late Friday into Saturday - though the model spread again increases into the weekend with the GFS bringing its next, much more southern, trough east into the area quicker than the ECMWF. For the most part, the blended solution was followed as a starting point for the grids, though the latest ECMWF was taken into consideration for the mid week system. Sensible weather will feature a very cold start to the work week as the latest late season winter storm pivots over the eastern Great Lakes keeping wrap around moisture and upslope flow going for eastern Kentucky. Along with the pcpn, very cold air aloft will support temperatures struggling to get out of the 30s and a mix of rain and snow showers around into the afternoon. Would not expect to see much in the way of accumulations given the warm ground sfcs heading into this, though some heavier showers may be able to leave some slush behind. That night will be quite cold with sub freezing temperatures expected in many places along with widespread frost due to high pressure moving through the area. A quick warmup follows for Tuesday ahead of the next fast moving upper level system and its weak sfc reflection. As this system approaches only limited moisture return will be available so that any pcpn will need to come from dynamics alone. Low PoPs will keep the thunder threat out of the grids for Wednesday into Wednesday night - though the threat is not zero. The cold front for this system goes through the area by Thursday morning with another shot of cooler air and a good chance for valley frost by Friday morning. Saturday warms back up quickly but showers may slip into the state from the west by evening - especially if the faster GFS solution has the right idea. Again used the CONSRaw for temperatures Monday and Monday night to better capture the chilly air mass. Also adjusted the low temps for several nights next week with ridge valley temp splits expected to develop basically every other night. As for PoPs, did not deviate much from the blend except to enhance the upslope effect on Monday. && .AVIATION...(For the 00Z TAFS through 00Z Sunday evening) ISSUED AT 835 PM EDT SAT APR 14 2018 Mainly VFR is observed across much of the region with some scattered MVFR in showers. Further saturation will occur as a pre cold front band of moderate to possibly heavy rain showers moves into the region during the 9Z to 12Z period. A thunderstorm This should lead to deterioration to MVFR at KSME with MVFR spreading east to LOZ around 12Z, SYM and JKL around 15Z and SJS and WV border by 18Z. Further deterioration to IFR from west to east 14Z to 20Z for about 5 hours along and behind a cold front. Winds will be out of the southeast to south ahead of the front through around 8Z before gradually shifting to the southwest from west to east as the front moves through. && .JKL WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...JP SHORT TERM...AR LONG TERM...GREIF AVIATION...JP
Area Forecast Discussion
National Weather Service Chicago/Romeoville, IL
1007 PM CDT Sat Apr 14 2018 .UPDATE... 1006 PM CDT Issued a winter weather advisory for patchy light freezing rain and glazing on roads and bridge decks for the northern tier of IL counties through 18Z Sunday. Still windy, though winds have slowly diminished below wind advisory criteria and allowed wind advisory to expire earlier this evening. Lakeshore Flood Warning remains in effect for Lake/Cook counties in IL until 10 am CDT Sunday. Surface low pressure continues to track slowly through central IL this evening, in association with deep upper trough drifting across the central CONUS. Warm, moist advection persists ahead of the trough, spreading north of the surface stationary/warm front to our south, and producing fairly extensive area of rain/showers across the area. While AMDAR soundings from MKE depict temperatures around +4C at 825 mb, gusty northeast low level winds have slowly cooled surface temps to the freezing mark (31-34 degrees) across the IL/WI border region, with rain causing some glazing on bridge decks and some roads (and mixing with some sleet too) per spotter reports over the past hour or so. Surface temps are expected to hold fairly steady overnight and RAP forecast soundings depict the thermal profile aloft will be maintained through the night and into Sunday morning, before temps aloft eventually cool enough to change things over to a snow/sleet mix. Thus freezing rain, at least in a patchy manner, will likely persist across the far northern tier of cwa counties into early Sunday. Since we`re already getting some reports of glazing on roads, went ahead an issued the winter wx advisory in collaboration with WFOs MKX and DVN. Otherwise, allowed wind advisory to expire earlier as planned. Still windy overnight, though speeds continue to very slowly diminish and have been below advisory criteria. Lakeshore flood warning also continues, as webcam images around the Oak Street curve/beach area showed the lake has topped the beach and bike path this afternoon. Updated digital/text products updated and available. Ratzer && .SHORT TERM... 244 PM CDT Through Sunday... No big changes planned in the near term. Strong mid-latitude cyclone is slowly moving east across the central CONUS. Another arc of rain is blossoming near the MS River in advance of the closed mid-upper level circulation. Morning soundings did show pocket of some mid-level steep lapse rates, which may be enough to support some weak elevated CAPE and allow a thunderstorm or two to develop later this afternoon into early this evening, mainly south of I-80. As the arc of rain pushes east, guidance suggests increasing coverage/intensity, so anticipating a fairly widespread, soaking rain across the area through tonight. A number of models have 2m temps over our northern tier of counties dropping to near or just below freezing tonight. Plenty of warm air aloft would suggest a freezing rain threat developing tonight for our WI border counties. Climatology would certainly not favor freezing rain in April, but given the fairly good model agreement in sub-freezing temps see no reason not to maintain freezing rain chances in the forecast for tonight. Sfc freezing line is currently well north into central WI and sfc winds are largely parallel to the thermal gradient, so advection is not that strong despite the strong winds. Given the uncertainties and expectation that ice accums tonight (if any) would be mainly confined to elevated surfaces, opting to not issue any headlines. Will brief the oncoming evening shift and allow them to monitor trends this evening to determine if a winter wx advisory may be needed. Wind over and near the lake have largely been under performing today. Earlier ship obs indicate that stability issues are likely playing a role and preventing the stronger winds aloft from mixing down. Have seen some occasional obs with wind advisory criteria winds well inland across north central IL, while closer to the lake and over the metro area winds have generally been solidly below criteria. It is still windy and given the sporadic advisory level gusts over western CWA, plan to just let the wind advisory continue through its scheduled expiration time at 00z. Given winds have been under performing over the lake, waves have also not been nearly as high as previously forecast. Checking with local official suggests that the lake shore flood impacts have been minimal thus far and of the nuisance variety. The event is underway, so don`t see much upside to changing the lakeshore flood warning back to an advisory. Rather, at this point, plan to just let the warning continue for now, as winds begin to come down this evening, the warning can likely be cancelled early. Finally, Sunday looks like we should get dry slotted with steadier rain likely tapering off to drizzle. Sunday looks drizzly and cold, though by late in the afternoon into the evening deeper moisture wrapping around the cyclone should provide for ice nuclei needed for drizzle to change over to some snow as the column cools below freezing. This change over looks to take place over northern central IL late in the afternoon or early in the evening slowly spreading east across the remainder of the CWA Sunday night. Some minor accums (generally less than an inch) could occur Sunday night on elevated and grassy surfaces. Northwest winds will begin to pick up again, only adding to the winter-like feel of the weather Sunday night. - Izzi && .LONG TERM... 231 PM CDT Monday through Saturday... By Monday morning, conditions will be settling down as the deep low pressure system continues to slowly lift through the eastern Great Lakes and into sern Canada. The sfc and upper lows will become more vertically stacked, with strong deep layer cold advection in nwly flow and slightly cyclonic curvature aloft. Some light snow should linger into the morning hours and then quickly change over to a rain/snow mix and then all rain through the day. Pcpn chances should shut down through the afternoon as sfc high pressure begins to build across the Middle and Upper Mississippi Valley. Temperatures should start out the day in the upper 20s to lower 30s and then rise into the upper 30s to lower 40s. The upper ridge and sfc high pressure should build across the region overnight Monday night and Tuesday as the old sfc low sits nearly stationary over sern Canada. A relative warming trend will begin Tuesday as a new low develops over the Central Plains and upper ridging builds over the Midwest. Temps through the rest of the period should be closer to seasonal normal levels with highs in mainly in the 50s and lows in the 30s. The next significant chance for pcpn will be late Tuesday night and Wednesday and the next low approaching the region. This system is expected to be more progressive and take a more northerly track than the system currently impacting the region, so while some light rain-rain/snow mix-snow will be possible, winds will likely not be nearly as strong, the pcpn will move through the area much quicker and temperatures will not be as low. More mild and dry conditions are expected for the end of the period as the system moves off to the east. However, with the general pattern expected to remain relatively high amplitude and progressive, the longer range guidance is suggesting that another system may bring another round of pcpn for next weekend. && .AVIATION... For the 00Z TAFs... With a deep low pressure system moving very slowly overhead, unsettled IFR conditions will remain in place for much of the forecast period. Cigs and vsbys may occasionally vary a bit higher or lower but the latest forecast reflects expectations for what would be most likely for the longest time periods. Northeast winds also will prevail through the night and into late morning before turning northwest during the afternoon. During the same late morning to early afternoon period there could be a short break in precipitation with improved visibilities before another shot of rain possibly mixing with snow moves in later in the day. Lenning && .MARINE... 231 PM CDT Gales are expected to continue over the lake as a low pressure system passes through the Mid Mississippi Valley tonight and strong high pressure remains parked over ern Ontario and wrn Quebec. The low will slowly lift across the Eastern Great Lakes Monday, reaching swrn Quebec Tuesday morning. The low will then weaken and dissipate by Wednesday. Winds should gradually diminish below Gale Force from south to north through the day on Sunday as weak high pressure approaches the Mississippi Valley. Another low is forecast to move over the lake Wednesday afternoon or evening, but the models are indicating some timing and intensity differences, so the general confidence in exact wind trends associated with the passage of this system is relatively low at this time. && .LOT WATCHES/WARNINGS/ADVISORIES... IL...Lakeshore Flood Warning...ILZ006-ILZ014 until 10 AM Sunday. Winter Weather Advisory...ILZ003-ILZ004-ILZ005-ILZ006 until 1 PM Sunday. IN...None. LM...Gale Warning...LMZ740-LMZ741-LMZ742-LMZ777-LMZ779 until 10 AM Sunday. Gale Warning...IN nearshore waters until 1 AM Sunday. Small Craft Advisory...LMZ743-LMZ744-LMZ745...1 AM Sunday to 5 PM Sunday. && $$ 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 Melbourne FL
944 PM EDT Sat Apr 14 2018 .UPDATE... ...Slight Risk Severe Storms All of EC FL on Sunday... ...Deteriorating Boating Conditions into Sunday... Tonight...There was one small cell that formed west of FPR/VRB this afternoon and a few cells were ongoing west of Lake Okeechobee, but the atmosphere was too dry/stable for anything more than that. However, surface dew points are around 70 already and increasing southerly low level flow will increase moisture depth overnight. Therefore will keep small PoPs as suggested by the GFS. Sunday-Sunday Night...Won`t make any changes to the previous forecast. The HRRR model has been showing the squall line moving east around 25 mph across the eastern Gulf of Mexico on Sunday morning. Recent runs and extrapolation show that the line should reach Lake county towards 19z and the I-4 corridor around 20z and south Brevard to Okeechobee near 22z. These times assume near steady state speed but the main takeaway is that the line should move across the area and take advantage of peak daytime heating. Additionally, isolated-scattered cells should form out ahead of the line during the afternoon. These would likely have the greatest veering of winds in the lower levels, with potential organization tapping into max daytime instability and producing a few strong- severe storms. Mid level temps won`t be that cool, but some lingering drier air should partially compensate and increase potential convective instability. The main storm threat will be damaging straight line winds, but a slight chance for tornadoes and large hail exists too. Previous Discussion... Expect a warm and windy Sunday with widespread rain/thunderstorms sweeping through in the afternoon and evening with the potential for severe thunderstorms in the afternoon and evening hours. Strong S-SW winds picking up early in the period and may need a Lake Wind Advisory by Sunday morning. Intensifying shortwave becomes negatively tilted over the SE states. Warm air advection strong over the area daytime Sunday with highs well into the 80s...and may top 90 across the southern interior and help destabilize atmosphere. Rapidly moving storms will cross the area ahead of the front. Latest model runs suggest main with timing of prefrontal storms in the late afternoon and early evening hours ...but may also see isolated strong to severe storms ahead of the main band earlier in the afternoon. Damaging straight line winds looks to be the primary threat, but an isolated tornadic cell will also be possible. Indicating a trend of highest PoPs in the north through the daytime hours, then highest PoPs shifting south Sunday night, before coming to an end from north-south overnight. Timing will likely need to be fine tuned as system gets closer. && .AVIATION...Mainly VFR tonight. Southerly low level winds will increase by around 14z Sunday with gusts to around 25 knots occurring. A squall line is forecast to sweep across all of the terminals during the afternoon and evening. Haven`t included tempo groups yet but the line should reach to around KLEE 18-19z and the Interstate 4 corridor 19-20z, then affecting KMLB-KSUA between 22z and 02z. This line will produce a severe weather threat, but isolated to scattered cells developing in the afternoon ahead of the line may also be strong to locally severe. && .MARINE... Tonight-Sunday...The pressure gradient will start to tighten overnight and produce south winds 15-20 knots especially across the south. Will keep current exercise caution headlines there. Winds will increase further on Sunday ahead of a strong cold front. Speeds will pick up to 20-25 knots, which will produce hazardous boating conditions over all of the waters. A squall line will traverse the waters during the late afternoon and evening hours. Several storms should produce wind gusts over 34 knots. && .MLB WATCHES/WARNINGS/ADVISORIES... FL...None. AM...Small Craft Advisory from 10 AM Sunday to 10 AM EDT Monday for Flagler Beach to Volusia-Brevard County Line 0-20 nm- Flagler Beach to Volusia-Brevard County Line 20-60 nm- Volusia-Brevard County Line to Sebastian Inlet 0-20 nm- Volusia-Brevard County Line to Sebastian Inlet 20-60 nm. Small Craft Advisory from 4 AM Sunday to 10 AM EDT Monday for Sebastian Inlet to Jupiter Inlet 0-20 nm-Sebastian Inlet to Jupiter Inlet 20-60 nm. && $$ SHORT TERM/AVIATION...Lascody IMPACT WX...Combs
Area Forecast Discussion
National Weather Service Pueblo CO
628 PM MDT Sat Apr 14 2018 .UPDATE... Issued at 626 PM MDT Sat Apr 14 2018 Quick update for issuance of Fire Weather Watch for Monday morning through Monday afternoon for portions of the forecast area. Also brought in latest obs and blended with forecast. && .SHORT TERM...(This evening through Sunday) Issued at 325 PM MDT Sat Apr 14 2018 ...Winds diminishing across the area this evening... Currently...Surface and upper level low pressure continue to slowly lift northeastward into the Midwest this afternoon, with pressure gradient gradually relaxing across the region. Only location to reach high wind criteria this afternoon has been Baca county around Springfield, while peak gusts farther north and west have stayed in the 35-45 kt range. With KPUX VAD showing winds below 40 kts in the surface through 13k msl layer, and HRRR depicting gust speeds decreasing below 40 kts 22z-23z, will cancel remaining high wind warning with new forecast issuance. Tonight...winds rapidly decrease this evening with loss of mixing and weakening pressure gradient, and expect speeds to drop below 15 kts at most locations after midnight. Given clear skies and dry air, min temps will be fairly cold, and readings at/below freezing are expected area-wide. Sunday...Weak surface high pressure dropping through the plains will turn winds sely along and east of the mountains by afternoon, though speeds will remain under 20 kts through late day. Models occasionally produce some isolated convection over the mountains in the afternoon as mid levels moisten slightly, but doubt we`ll see more than some modest convective cloud cover over the peaks and won`t include any pops. Max temps will warm considerably across the region as upper ridge builds and mid level temps rise, with 60s reappearing across the plains and most interior valleys. .LONG TERM...(Sunday night through Saturday) Issued at 325 PM MDT Sat Apr 14 2018 ...Increasing wind once again for Monday and Tuesday... Sunday night and Monday...The upper ridge axis crosses the state Sun night, with increasing southwest flow aloft expected for Mon as the next upper low pressure trough approaches the West Coast. This will help to keep dry conditions in place as well as boost aftn highs. The warm dry conditions coupled with increasing winds will likely push fire weather conditions to near critical for the San Luis Valley as well as the southern foothills. Max temps Mon are forecast to warm into the 60s to around 70F for the high valleys, and 70s to around 80F for the eastern plains. Tuesday...The next weather system crosses the Great Basin very early Tue, then crosses the rockies and brushes by the northern half of Colorado Tue and Tue night. This will bring 3 to 4 inches of new snow to the higher terrain, with the highest amounts expected over the central mts. For the rest of the forecast area, the main concern will be another rough of very strong west to southwest winds, boosting dry and warm conditions and enhancing fire danger. Look for highs in the 50s for the high valleys, and 60s to mid 70s for the plains. Wednesday and Thursday...As the first system passes to the east, a temporary ridge will track across the region midweek. Lighter winds and mild but dry conditions are expected. Maximum temps will warm into the 50s to lower 60s for Wed, then 60s to lower 70s for Thu. Friday and Saturday...Extended models agree on bringing another upper low pressure system into the region for the weekend, with snow beginning over western CO early Fri morning, then crossing the entire state Fri into Sat as the low passes overhead. Exact pcpn location and amounts are still a question this far out, but increased cloud cover and cooler temps are a good bet. Look for highs both days in the 50s to mid 60s for most locations. Moore && .AVIATION...(For the 00Z TAFS through 00Z Sunday evening) Issued at 325 PM MDT Sat Apr 14 2018 VFR conditions at all taf sites the next 24 hrs, with winds becoming light drainage/downslope overnight. On Sunday, winds will become S- SE at all sites, while speeds remain below 15 kts. && .PUB WATCHES/WARNINGS/ADVISORIES... Fire Weather Watch from Monday morning through Monday evening for COZ222-224-225-228>230-233. && $$ UPDATE...LINE SHORT TERM...PETERSEN LONG TERM...MOORE AVIATION...PETERSEN
Area Forecast Discussion
National Weather Service Charleston WV
808 PM EDT Sat Apr 14 2018 .SYNOPSIS... Cold front crosses Sunday, bringing thunderstorms and heavy rain followed by snow due to colder air Monday. High pressure Tuesday. Another cold front Wednesday. && .NEAR TERM /THROUGH SUNDAY/... As of 755 PM Saturday... boundary is really doing a number on temps and dewpoints as it progresses east through the CWA. Temps have fallen into the upper 60s and lower 70s, with dewpoints rising into the lower 60s behind the boundary. Most if not all of the shower activity should remain confined to along and northwest of the Ohio River this evening. Impressive temp gradient showing up across the upper Ohio Valley, north of an impressive baroclinic zone. This may slip south into Perry/Morgan overnight before retreating north again as low pressure approaches. I used the HRRR to update the hourly grids which reflects this boundary moving through. All in all a very pleasant evening east of the Ohio River. No changes made for Sunday. As of 245 PM Saturday... Cold front slowly approaches from the west tonight and eventually crosses the region on Sunday. All models indicating a strong LLJ out ahead of the front and punching into West Virginia by Sunday afternoon. Not surprising, with the moisture pumping in, that GEFs highlight PWAT anomalies of 2 to 3 std deviations. Also, moisture flux at 850 mb of 5 std deviations crosses the region tomorrow afternoon and evening. Most of the guidance continues to pound the Eastern Mountains with 2 inches or more of QPF, so with the afternoon forecast package we have decided to issue a flash flood watch for the Eastern Half of the CWA. This area matches well with WPC new Day 2 excessive rainfall outlook, but was still uncertain how far westward to bring the watch. May need to expand at a later time, but for now we will highlight the heavy rain threat outside the watch in the HWO. Also, there will be a low chance for severe storms tomorrow based on the low instability that will likely be in place across the region. CAPE values fail to reach above 500 J/Kg in the latest model soundings, and this makes sense with likely ongoing precipitation Sunday. However, as mentioned earlier, a strong LLJ near 60 knots at 850 mb and with strong shear, would not be surprised to see a few strong embedded thunderstorms with localized damaging downdrafts. SPC has highlighted a large portion of the area in a Marginal Risk Sunday, we will continue to highlight these chances in the HWO. && .SHORT TERM /SUNDAY NIGHT THROUGH TUESDAY/... As of 315 PM Saturday... A sfc low pressure center, and its associated cold front will cross the local area Sunday night. Models show temperatures warm enough to produce liquid pcpn for the most part Sunday night. Then, much colder air filters in behind the front to aid on the upslope snow over the northeast mountains Monday, under northwest flow. Snow accumulations will not be significant, coded 1-2 inches over highest elevations. By Sunday night, 1-1.5 inches of rain for the middle Ohio River Valley, with some amounts over two inches in the WV mountains, pose a threat for water problems, first on small creeks and streams, but then possibly even along some main stem rivers as the water drains through the system into midweek. Will continue HWO mention of potential flooding. Decent wraparound moisture flow into Tuesday. As 850mb temps drop into the -5C to -8C range late Monday into Monday night expect rain to transition to snow. Have some minor accumulations in the mountains of generally and inch or two. && .LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/... As of 315 PM Sunday... Brief high pressure will cross Tuesday night -- although the GFS is now trying to show some shower activity associated to a warm front along US route 50. Did not include this just yet. A quick moving low pulls a cold front through Wednesday night or Thursday. The GFS is faster than the ECMWF with this. Went mostly dry Thursday night into Friday but models are inconsistent with the synoptic pattern so confidence is rather low. && .AVIATION /00Z SUNDAY THROUGH THURSDAY/... As of 800 PM Saturday... VFR conditions through 15Z. Boundary pushing into the mountains may allow for some brief gusts at BKW/EKN to 30 kts in the first hour. Otherwise, showers will stay confined to areas along and north of the Ohio River this evening, clipping PKB early. Cold front approaches and crosses Sunday afternoon with IFR in showers and possibly a few storms. Expect gusty winds and marked wind shift with fropa. Timing of front would keep CKB and EKN clean until the last hour or two of the taf period. FORECAST CONFIDENCE AND ALTERNATE SCENARIOS THROUGH 00Z MONDAY... FORECAST CONFIDENCE: High today, medium tomorrow. ALTERNATE SCENARIOS: Widespread convection could develop earlier than expected tomorrow. EXPERIMENTAL TABLE OF FLIGHT CATEGORY OBJECTIVELY SHOWS CONSISTENCY OF WFO FORECAST TO AVAILABLE MODEL INFORMATION: H = HIGH: TAF CONSISTENT WITH ALL MODELS OR ALL BUT ONE MODEL. M = MEDIUM: TAF HAS VARYING LEVEL OF CONSISTENCY WITH MODELS. L = LOW: TAF INCONSISTENT WITH ALL MODELS OR ALL BUT ONE MODEL. DATE SUN 04/15/18 UTC 1HRLY 00 01 02 03 04 05 06 07 08 09 10 11 EDT 1HRLY 20 21 22 23 00 01 02 03 04 05 06 07 CRW CONSISTENCY H H H H H H H H H H H M HTS CONSISTENCY H H H H H H H H H H H M BKW CONSISTENCY H H H H H H H H H H H M EKN CONSISTENCY H H H H H H H H H H H M PKB CONSISTENCY H H H H H H H H H H H M CKB CONSISTENCY H H H H H H H H H H H M AFTER 00Z MONDAY... IFR likely in showers and thunderstorms Sunday and Sunday night. && .RLX WATCHES/WARNINGS/ADVISORIES... WV...Flash Flood Watch from Sunday morning through late Sunday night for WVZ015-016-018-024>034-039-040-515>526. OH...None. KY...None. VA...None. && $$ SYNOPSIS...ARJ/MPK NEAR TERM...MPK/30 SHORT TERM...ARJ LONG TERM...ARJ AVIATION...30
Area Forecast Discussion
National Weather Service Tallahassee FL
757 PM EDT Sat Apr 14 2018 .UPDATE... Overall, severe weather potential still looks on track for tonight into Sunday morning. The squall line is starting to show some eastward progress after temporarily stalling across portions of SE MS and southern AL earlier this afternoon. Following the synoptic scale trends in the hourly RAP guidance so far, an enhancement in the low-level jet is expected to develop this evening with 850 mb winds increasing to 50-60 knots across portions of southeast Alabama and the Florida panhandle later tonight. This makes sense as the synoptic scale upper trough takes on more of a negative tilt and dynamics become more favorable for the line to accelerate eastward. There are some differences in guidance with respect to instability with an ensemble of CAM guidance showing 1000-1500 j/kg of SBCAPE across the Florida panhandle in the 06-09z time frame, whereas the RAP has been showing values in the 400-1000 j/kg range. Either way, instability looks sufficient given the more favorable dynamics to support strong to occasional severe storms along the squall line as it moves eastward across the area tonight into Sunday morning. Given the strong low level shear thanks to the increased low-level jet, an isolated tornado or two cannot be ruled out along the QLCS either, especially if a weak mesolow develops along the line and moves northeastward. That bears watching as any weak mesolow development would cause localized backing of the surface winds, which would make the hodograph more favorable. A tornado watch is possible later tonight, mainly for the western half of the forecast area. && .AVIATION [Through 00Z Monday]... MVFR cigs will develop and spread eastward later this evening with cigs and vsbys deteriorating further overnight into Sunday morning as a line of TSRA advances across our region. Tried to time the onset of heaviest convection based on latest radar trends. Arrival time at DHN/ECP around 06-08Z, ABY/TLH around 09-12Z, & near VLD around 12-14Z. Conditions will gradually improve from west to east Sunday afternoon in the wake of the cold frontal passage. && .PREV DISCUSSION [329 PM EDT]... .NEAR TERM [Through Sunday]... Radar and satellite imagery are showing the 18Z and 15Z positions of the line of storms to be roughly 2-3 hrs ahead of the GFS, NAM, and RUC guidance. The HRRR is running the closest, but only goes out 18 hours and therefore doesn`t depict the full movement of the line across our area. With more forward speed than the models have been showing, we`ll likely see storms a few hours earlier than we were originally thinking. Although this afternoon will remain clear locally, the squall line may move into the area earlier in the evening tonight. The severe threat in southeast AL and the FL Panhandle could be starting closer to 9 PM CT/10 PM ET as opposed to 1 AM CT/2 AM ET as we had been looking at previously. This earlier timing would also mean more instability on tap for the storms to work with. Our local ensemble of hi-res guidance has SBCAPE up to 1000-1500 J/kg overnight, with the highest values along the Panhandle coastline. Even the GFS, which is running about 3 hours slower has CAPE around 1000 J/kg over the area. Dynamically, this system has a strong low level jet and strong low level and deep layer shear. The 850 mb winds will be 50+ kts over the area tonight. 0-1 km shear is 30+ kts and 0-6 km shear is 50+ kts. The area remains under a slight risk for severe thunderstorms tonight through Sunday with the main threat being damaging wind gusts and possibly a few tornadoes along the squall line. Light rain will persist for a few hours behind the squall line, but given current trends, the rain may exit our area by 5 PM ET Sunday. .SHORT TERM [Sunday Night Through Monday Night]... Upper level low will be situated over the Ohio Valley region tomorrow night and lift northward through the short term, eventually bringing upper level winds to the northwest by Monday night as an upper level ridge across the western CONUS pushes eastward. The cold front from the near term will be east of the area by Sunday night with surface high pressure building in and the center of the high pushing into the CWA Monday night. Behind the cold front that will move through tonight into Sunday, the CWA will remain dry through the short term. Highs will reach into the mid to upper 60s on Monday. Lows will drop into the low to mid 40s. .LONG TERM [Tuesday Through Saturday]... Much of the long term will be dry. The aforementioned surface ridge will slide eastward on Tuesday and into the Atlantic Wednesday as another front pushes across the Plains and into the southeast. While a few showers cannot be ruled out as the front pushes through on Thursday, at this time, precipitation appears to be limited and forecast only calls for 10 percent PoPs. The main impact will be an increase in cloud coverage. The next system of interest will be as another front approaches for late in the weekend. There is quite a bit of difference in the models at this point but both indicate the chance of increasing PoPs late in the weekend. .MARINE... A cold front will move through the marine area tonight through Sunday, bringing showers and thunderstorms to the area tonight and Sunday. Winds and seas will continue to increase this afternoon with Small Craft Advisory conditions spreading eastward tonight. Conditions will subside on Monday. High pressure will build in for the beginning of the week but another weak front is expected on Thursday, although at this time, little impacts are expected from it. .FIRE WEATHER... Wetting rains will arrive ahead of a cold front late tonight into Sunday. A much drier airmass will be in place Monday and Tuesday but red flag conditions are not expected. High dispersion values will be possible both Sunday and Monday afternoon. .HYDROLOGY... One to two inches of rain, with isolated higher amounts, is expected as the squall line moves through tonight into Sunday. Based on these values, a river point or two could reach action stage, however river flooding isn`t expected. Some ponding of water in low lying areas could occur, but widespread flooding is not expected. .SPOTTER INFORMATION STATEMENT... Spotter activation is requested. Spotters should safely report significant weather conditions and/or damage by calling the office or tweeting us @NWSTallahassee. && .PRELIMINARY POINT TEMPS/POPS... Tallahassee 66 71 44 69 42 / 70 100 0 0 0 Panama City 63 68 50 68 52 / 100 90 0 0 0 Dothan 60 68 43 67 43 / 100 100 0 0 0 Albany 68 70 43 66 44 / 70 100 0 0 0 Valdosta 65 72 45 66 43 / 50 100 0 0 0 Cross City 67 75 47 68 44 / 40 100 0 0 0 Apalachicola 66 72 47 67 48 / 80 100 0 0 0 && .TAE WATCHES/WARNINGS/ADVISORIES... FL...High Rip Current Risk through late Sunday night for Coastal Bay- Coastal Franklin-Coastal Gulf-South Walton. High Surf Advisory until 8 AM EDT /7 AM CDT/ Monday for Coastal Bay-South Walton. High Surf Advisory from 2 AM EDT /1 AM CDT/ Sunday to 11 AM EDT /10 AM CDT/ Monday for Coastal Gulf. GA...None. AL...None. GM...Small Craft Advisory from 2 AM Sunday to 2 PM EDT Monday for Apalachee Bay or Coastal Waters From Keaton Beach to Ochlockonee River FL out to 20 Nm-Coastal Waters From Ochlockonee River to Apalachicola Fl out to 20 Nm-Coastal waters from Suwannee River to Keaton Beach FL out 20 NM- Waters from Suwannee River to Apalachicola FL from 20 to 60 NM. Small Craft Advisory until 2 PM EDT Monday for Coastal waters from Mexico Beach to Apalachicola FL out 20 NM-Coastal waters from Mexico Beach to Okaloosa Walton County Line FL out 20 NM-Waters from Apalachicola to Mexico Beach FL from 20 to 60 NM-Waters from Mexico Beach to Okaloosa Walton County Line FL from 20 to 60 NM. && $$ UPDATE...DVD NEAR TERM...Nguyen SHORT TERM...Fieux LONG TERM...Fieux AVIATION...Barry MARINE...Fieux FIRE WEATHER...Barry HYDROLOGY...Fieux