Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 01/10/21

Area Forecast Discussion
National Weather Service Gaylord MI
906 PM EST Sat Jan 9 2021 .UPDATE... Issued at 906 PM EST Sat Jan 9 2021 Slow cold advection continues, on wnw 1000-850mb winds. 850mb temps lower to around -4C by morning. That isn`t actually /cold/ of course (at least for January), but it will gradually make it a little easier to generate weak lake convection. We are already doing so on Superior, via MQT radar and very weak returns occasionally from Montreal Rvr. Obs also back this up, with light precip at times at the Chippewa Co sites, and 4SM in -SHSN at Sault Canada. Will continue to boost and expand pops in Chippewa Co tonight, though nothing more than sct pops, and nothing more than a dusting of new snow. Another spot where pops have been added is near Presque Isle Lt, where the HRRR spits out a bit of precip. Eventually, a lake effect snow threat will emerge in nw lower MI, but there is no sign of that yet. Chance for that will probably be highest very late tonight, perhaps near Ltl Trav Bay. Will reduce pops a bit in the early tonight period in nw lower MI. UPDATE Issued at 626 PM EST Sat Jan 9 2021 Sct lake effect snow showers have pushed into eastern upper MI, per obs from ERY/Kinross/Sault Canada. Forecast updated to reflect this. && .NEAR TERM...(Through Sunday) Issued at 332 PM EST Sat Jan 9 2021 ...Cloudy skies with some light precip.. High Impact Weather Potential: Minimal. Some fog again tonight along with light lake induced precip. Pattern Synopsis/Forecast: Split relatively weak upper flow pattern is across NOAM along with a broad expanse of surface high pressure across a large portion of the CONUS. Lots of low level moisture/stratus also spans a large portion of the central CONUS and Midwest, stuck under a strong subsidence inversion. After yesterdays sunshine, stratus managed to rotate back into eastern Upper and a good portion of northern Lower Michigan this morning. But with heating/mixing, stratus advancement was halted with the SE counties enjoying sunny conditions. Northern stream short-wave trough in Ontario this afternoon will slip down into the northern lakes region tonight through Sunday. Along with gradual lower level cooling and moistening, modest QG- forcing for ascent and increasing inversion, high-res CAM guidance kick of some very modest lake induced precip...spreading into parts of eastern Upper and NW Lower Michigan tonight into Sunday. Nothing to dramatic...some flurries, spotty light snow showers or perhaps a touch of freezing drizzle anticipated for parts of the forecast area. Otherwise, after sunset stratus will more than likely spread into the rest of northern Lower Michigan for tonight, leading us into another rather cloudy day once again on Sunday. Low temps tonight may again be tricky across SE counties as there will be a window of opportunity for temps to tumble before stratus fills in. Given what occurred last night, I may not be cold enough with tonights lows across those && .SHORT TERM...(Sunday night through Tuesday) Issued at 332 PM EST Sat Jan 9 2021 ...The Early Part of the Week... Impact Weather Potential...Minimal. Pattern Synopsis/Forecast...Continued weak high pressure will little disturbances through the 48 hour of the short term period gives us barely slight chances for snow in the NW LES flow, mainly Sunday night. sfc to 850 mb delta Ts barely get to 12C only for things to warm and stabilize. A few of the CAMs produced some precipitation (along with the GFS) so added the pops into the forecast area Sunday evening. Then things dry out and looks to remain that way until Wednesday. .LONG TERM...(Tuesday night through Saturday) Issued at 332 PM EST Sat Jan 9 2021 High Impact Weather Potential...Lake Effect is possible during the end of the work week. Extended (Tuesday night through Saturday)...Tuesday night into Wednesday, high pressure continues over the region. Thursday, The models have flipped the timing with the ECMWF more aggressive with the front moving through Wednesday night, and the GFS on Thursday. Thursday night, the models show the cold 850 mb air moving in with the GFS, while the ECMWF being a little slower and less aggressive with the cold air on Friday. Friday night, the ECMWF does get cold enough for LES, while the GFS has been there for about a day. Saturday, LES will continue on both models, until 00z/Sun when the thermal ridge moves in and begins to warm and dry the low levels, shutting off the LES. && .AVIATION...(For the 00Z TAFS through 00Z Sunday evening) Issued at 626 PM EST Sat Jan 9 2021 MVFR cigs. Stratus/stratocu covers most of the area, and is not expected to relent thru the TAF period. MVFR cigs will prevail. Would not rule out cigs barely and briefly dipping to IFR. Light lake effect snow showers could form in nw flow, though most of this activity will remain between TVC and PLN. Light winds. && .MARINE... Issued at 332 PM EST Sat Jan 9 2021 Lighter winds/waves persist tonight through Sunday. However, SW flow increases Sunday night into Monday with small craft advisory headlines a good bet for much of the northern Michigan nearshore areas. && .APX WATCHES/WARNINGS/ADVISORIES... MI...NONE. LH...NONE. LM...NONE. LS...NONE. && $$ UPDATE...JZ NEAR TERM...TBA SHORT TERM...JL LONG TERM...JL AVIATION...JZ MARINE...BA
Area Forecast Discussion
National Weather Service Grand Forks ND
918 PM CST Sat Jan 9 2021 .UPDATE... Issued at 918 PM CST Sat Jan 9 2021 Had thought the dense fog across the Devils Lake region and around Fergus Falls would bounce up and down like other areas. However it remains at or less than a quarter of a mile, so stuck out a dense fog advisory for those areas through tonight. Like the past few nights, the areas may need to be expanded or cut back, will just have to keep an eye on current conditions and adjust as needed. Temperatures are dropping in the clear holes, and the latest satellite imagery shows some fog/stratus starting to fill back in some of these areas. So will be watching these areas as well for rapid drops in visibility. UPDATE Issued at 638 PM CST Sat Jan 9 2021 Fog and low clouds will be the main challenge tonight. Right now, the lowest visibilities are from Cando to Langdon, at one quarter of a mile. Elsewhere, visibilities have improved. There is still a westerly wind component to the surface winds, which is holding in the 5 to 10 mph range. This is expected to decrease overnight. In addition, there are some clear holes across the northern FA. Fog could form along these clear areas, or it could thicken again in other areas. So like most of the past 5 nights, there is some uncertainty yet in regard to the fog and low clouds. Will keep a close eye on visibilities, and adjust as needed. && .SHORT TERM...(This evening through Sunday night) Issued at 218 PM CST Sat Jan 9 2021 Impacts from fog possible tonight, mainly west central Minnesota. Satellite has been showing increasing southeast push of clearing into NE ND and far NW MN. One finger of clearing down to NW of Grand Forks from Pembina. Overall expected trend tonight into Sunday will be gradual clearing of the low level moisture southward...with NAM/HRRR indicate drier air at 925 mb dropping south thru the Red River valley reaching Fargo by 12z Sun. Clearing also west thru DVL basin to Valley City and east thru NW MN to about Bemidji. Unsure how much clearing will despite 925 mb lower RH moving in, so played it more conservative in the cloud dept tonight keeping S/E areas of the fcst with clouds all night and scattered clouds N/NW areas of the fcst area (ROX-GFK-DVL). With a bit drier air in the low levels moving in and a slowly increasing wind at 925 mb moving in tonight not expecting as much dense fog as past nights. HRRR indicates main fog potential is east of the Red River valley in WC MN. SPS is out and will update it to mention patchy dense fog tonight in west central MN. Lows tonight tricky. Guidance has been too cool in low cloud areas, but when clears temps will drop. Sunday should see some sunshine over more of the area before clouds increase Sun night. 925 mb temps cool a tad Sunday but with sun will see plenty of upper 20s and low 30s. .LONG TERM...(Monday through Saturday) Issued at 218 PM CST Sat Jan 9 2021 Warming continues to start the workweek, with impactful weather being kept to a minimum. An upper level ridge in west will keep the NW flow in place for the area, and bringing in some warmer temperatures. We will warm into the upper 30s and possibly even the low 40s heading into mid-week in the northern plains. As we begin to slide into the weekend, a system is expected to move through the Red River Valley early on Thursday, bringing some precipitation. However, confidence in timing, track, and other finer details is low. In line with previous guidance, moisture continues to lack with this possible system, and forecasted temperatures pose a problem with precipitation type as well. A wintry mix could be seen in the areas affected, which looks to be southern North Dakota as of now. && .AVIATION...(For the 00Z TAFS through 00Z Sunday evening) Issued at 638 PM CST Sat Jan 9 2021 Generally expect fog and/or stratus to continue overnight, it is just a matter of how bad and where. Overall, it is unlikely the thick dense fog that occurred the past few nights will be found in this area overnight. Visibilities will likely come down at least into the MVFR range, and the stratus will likely continue where it is at. Surface winds pick up on Sunday, which should finally help scour this out. && .FGF WATCHES/WARNINGS/ADVISORIES... ND...Dense Fog Advisory until 9 AM CST Sunday for NDZ006-007-014-015- 024-026-054. MN...Dense Fog Advisory until 9 AM CST Sunday for MNZ030-040. $$ UPDATE...Godon SHORT TERM...Riddle LONG TERM...AK/Riddle AVIATION...Godon
Area Forecast Discussion
National Weather Service Green Bay WI
525 PM CST Sat Jan 9 2021 Updated aviation portion for 00Z TAF issuance .SHORT TERM...Tonight and Sunday Issued at 226 PM CST Sat Jan 9 2021 The latest RAP analysis and satellite/radar imagery show high pressure stretching across much of the northern Plains into the western Great Lakes early this afternoon. Widespread cloud cover remains present beneath a stout inversion, though some breaks in the overcast may yet occur this afternoon since moisture is relatively shallow. Tough to pinpoint where this will occur, but northwest flow would favor the downsloping areas of NE WI. Will show some decrease in the clouds there. Looking upstream, a shortwave trough is diving south into northern Minnesota. No precip is occurring near the trough, but skies are clearing over south-central Canada behind the trough. Like the past several days, forecast concerns mainly revolve around sky trends and temps. Tonight...Should any holes in the overcast occur, expect them to fill back in by mid to late evening. Mid and upper moisture look to increase ahead of the shortwave trough, which is forecast to move across the region late tonight. Looking at forecast soundings, a large dry wedge continues to exist between 3000 ft to 12000 ft above ground level. As a result, precip chances look quite low. The only chance of precip would be if shallow boundary layer moisture can grow deep enough for flurries or freezing drizzle, but this too doesn`t appear will be sufficient. Will leave the forecast dry. With the cloud cover, don`t expect temps to fall much. Sunday...Ample cloud cover will likely remain present in the morning. But as winds shift to the north behind the trough, there is potential for enough dry air to infiltrate the region and bring clearing skies from late morning through the afternoon. The stout inversion will remain, however, and the airmass is not very different from the current one, so not as optimistic as the numerical and statistical guidance with this possibility. Will show the clearing trend but slow it down comparatively speaking. High temperatures ranging from the middle 20s to lower 30s. .LONG TERM...Sunday Night Through Saturday Issued at 226 PM CST Sat Jan 9 2021 Periodic small precipitation chances and a return to near-normal temperatures late next week are the main forecast concerns. A short wave trough and associated weak cold front will move through the region Monday night. The GFS is much more vigorous with the short-wave than the ECMWF, so this will need to be monitored. Regardless, it appears that moisture will be very shallow, so will carry a dry forecast for now. If precipitation occurs, it will most likely be in the form of light freezing drizzle or flurries, and mainly over northern WI. Another weak short-wave and cold front are progged to move through the region Tuesday night into early Wednesday. The ECMWF is a bit stronger then the GFS with this system, but once again, moisture issues preclude any mention of measurable precipitation. Above normal temperatures will remain over the forecast area for the early to mid part of the week, with high temperatures peaking in the middle to upper 30s on Wednesday. This will occur as WAA ramps up in advance of the next frontal system approaching from the Northern Plains. The ECMWF is faster than the GFS with the arrival of a cold front Wednesday night into Thursday, and a stronger secondary cold front Thursday night into Friday. These frontal systems will likely produce scattered snow showers or flurries, with the potential for minor lake-effect in north central WI Friday into Saturday. The biggest impact will be a return to colder, but still near-normal, temperatures Friday into Saturday. && .AVIATION...for 00Z TAF Issuance Issued at 525 PM CST Sat Jan 9 2021 Low clouds continue to plague the area through much of this TAF issuance along with some patchy fog. Ceilings were dropping into the 400-800 ft range across central/north-central WI this evening, impacting the AUW/CWA/RHI TAF sites. The eastern TAF sites are benefiting from downsloping winds, which has allow clouds to scour out early this evening. VFR to MVFR conditions can be expected at ATW/GRB/MTW early in the TAF period before MVFR cloud cover builds back in late in the evening and overnight. The clouds will then linger across the area through much of the day Sunday. && .GRB WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHORT TERM.....MPC LONG TERM......Kieckbusch AVIATION.......Cooley
Area Forecast Discussion
National Weather Service Marquette MI
541 PM EST Sat Jan 9 2021 .SHORT TERM...(This evening through Sunday) Issued at 345 PM EST SAT JAN 9 2021 WV imagery and RAP analysis indicated a split flow pattern with an upstream shortwave trough from northwest Ontario into northern MN. At the surface, ridging prevailed from the northern Plains into the Upper Mississippi Valley resulting light northwest flow through the northern Great Lakes. Abundant low level moisture persisted across Upper Michigan with low clouds limiting temps to the mid and upper 20s west and lower 30s east. Radar indicated some very light lake effect pcpn with mainly light flurries and possibly some fzdz. Tonight, with relatively weak 700-300 qvector conv and little moisture inflow, little or no pcpn is expected with the approaching shrtwv. However, it may help to temporarily lift the 3k inversion and bring a slight boost to the lake effect pcpn for northwest wind favored locations. With the top of the moist layer only to around -8C to -9C, ice nuclei may also be lacking but recent trends/observations suggest that there may still be enough to support some snow. Any amounts should only amount to a trace to a hundredth of two. Otherwise, clouds will persist with lows from the upper teens inland west to the mid 20s near the Great Lakes and east. Sunday, as the ridge builds into the southern Great Lakes westerly low level dry advection should finally bring some clearing and sunshine into the area by afternoon after another morning with areas of fog. The sun will help boost temps into the low to mid 30s, warmest near the Great Lakes especially where downslope winds prevail. .LONG TERM...(Sunday night through Saturday) Issued at 236 PM EST SAT JAN 9 2021 A change in the pattern is on its way, but still have to get through the first half of next week to get there. Split flow looks to persist through at least the middle part of this week before troffing along Alaska weakens as the western CONUS ridge shifts west towards Alaska. By Thursday night, pattern becomes more amplified with ridging along the West Coast with troffing and NW flow across the Great Lakes. With this troffing, the lake-effect snow machines will dust themselves off and turn back on. In the mean time, expect limited pcpn and above-normal temperatures through Thursday morning, trending back towards normal for Friday with several days worth of pcpn chances. As the southern stream drops more snow in Texas than Upper Michigan has seen for 2 weeks, a northern stream shortwave will pass across Upper Michigan Sunday night into Monday. This brings some resemblance of winter across the western half of Superior with winds gusting in excess of 30 knots again, which looks to bring some gusting winds to the Keweenaw as folks wake up Monday morning. With some forcing from the shortwave and cooler temps, there is a slight chance of some brief LES across the west, but have left out of the fcst right now. NCEP solns appear to keep temps aloft right on the border of snow potential as GEM/EC fall as low as -9/-10C. Seeing as snow amts are minimal, felt fine waiting another cycle. GFS remains an outlier heading into Tuesday night, having 850mb temps fall to - 10C, fcst will remain dry at this time. WAA Tuesday night increases ahead of another, albeit weaker, shortwave passes across the UP late Tuesday night. Shouldn`t produce any pcpn, but Wednesday does look to be the warmest day of the week, with highs potentially up to 40...but otherwise comfortably in the mid 30s. By Thursday, the shift gets into motion as NW flow returns and a sfc low passes along Lake Superior, with increasing CAA moving over Upper Michigan. Models still have some details to shake out with degree of CAA, sfc low pressure, and placement...GEM brings sfc low across the UP and EC/GFS remains to the north of the lake. Regardless of how it plays out, all models have 850mb temps cool enough for LES by Thursday evening. GFS remains the coldest, and persists the longest. GEM/EC bring in rising heights Saturday night, which will cut off LES chances, at least briefly, before CAA picks back up and LES chances begin again Sunday night into Monday. && .AVIATION...(For the 00Z TAFS through 00Z Sunday evening) Issued at 541 PM EST SAT JAN 9 2021 Low ceilings will persist at the terminals through tonight. LIFR conditions expected at IWD and CMX with MVFR conditions at SAW. Look for improvement Sunday afternoon as drier air moves in with increasing westerly low level flow. && .MARINE...(For the 4 PM Lake Superior forecast issuance) Issued at 345 PM EST SAT JAN 9 2021 Light winds are expected across the lake into Sunday. A trough moving through northern Ontario Sunday night will result in increasing WSW winds to around 25-30 kts over the west and north- central, with a few gale force gusts possible at higher platforms. Winds will subside below 20 kts by Monday afternoon and remain below 20 kts through at least Wednesday. A pattern shift is still looking likely for the end of next week which would bring a return to colder weather that is more normal for January. && .MQT WATCHES/WARNINGS/ADVISORIES... Upper Michigan... None. Lake Superior... None. Lake Michigan... None. && $$ SHORT TERM...JLB LONG TERM...JAW AVIATION...07 MARINE...JLB
National Weather Service Morristown TN
931 PM EST Sat Jan 9 2021 .UPDATE... EVENING UPDATE. && .DISCUSSION... Satellite trends continue to show low cloud cover across most of the area tonight with the exception being southwest North Carolina. The strength of the low level inversion should keep cloud cover in place through the rest of the night and into Sunday. Some guidance is beginning to pick up on this scenario so adjusted sky grids to show mostly cloudy skies into Sunday morning. The cloud cover has kept temperatures a touch warmer and adjusted hourly temperatures and overnight lows accordingly. Otherwise the forecast is in good shape with no additional updates planned. Will go ahead and send an updated ZFP shortly. Diegan && .AVIATION... 00Z TAF DISCUSSION. A stubborn stratus deck continues to keep MVFR flight rules at all sites this evening. The RAP depicts this moisture well and between 900-950mb. Guidance suggests this stratus should stick around to around 06Z tonight and will scatter out. However, this is low confidence and later amendments may be needed if this stratus persists. Northerly winds will gradually veer toward the northeast through the period remaining between 5 and 10 knots. Diegan && .PRELIMINARY POINT TEMPS/POPS... Chattanooga Airport, TN 27 47 31 46 35 / 0 0 0 60 50 Knoxville McGhee Tyson Airport, TN 24 43 28 44 34 / 0 0 0 50 50 Oak Ridge, TN 25 44 28 44 33 / 0 0 0 50 50 Tri Cities Airport, TN 20 44 25 44 32 / 0 0 0 30 50 && .MRX WATCHES/WARNINGS/ADVISORIES... NC...NONE. TN...NONE. VA...NONE. && $$
Area Forecast Discussion
National Weather Service Tallahassee FL
815 PM EST Sat Jan 9 2021 .UPDATE... The low level cloudiness that has been with us since Friday is expected to gradually diminish overnight. Winds will also subside and this will allow temps to drop to near or just below the freezing mark by daybreak along with patchy frost. No changes were made to the current forecast package. && .PREV DISCUSSION [633 PM EST]... .NEAR TERM [Through Sunday]... The 12z KTAE sounding revealed a shallow layer of low level moisture up to around 900 mb that is responsible for the low clouds across the area. Very dry air exists above 900 mb. This cloud cover will persist through the afternoon and can tend to persist longer than guidance indicates. In fact, the HRRR has cloud cover persisting into the overnight hours. If this were to happen, then overnight lows would be warmer than most of the guidance currently shows. The official forecast went above the NBM guidance for low temperatures given the potential for this thin layer of clouds to persist, which the NBM appears to scatter out too quickly. Patchy frost remain possible tonight. For Sunday, partly cloudy skies are expected with highs generally in the 50s. .SHORT TERM [Sunday Night Through Monday Night]... Weak perturbations ahead of an eastward-moving shortwave trough over TX should allow for increased cloud cover across our area late Sun prior to the rainfall arriving. The sky cover combined with moist, easterly flow will raise Mon morning low temperatures by several degrees. Meanwhile, a surface low develops near its parent shortwave and traverses the north Gulf coast. Scattered showers and isolated storms (mainly over the waters) are expected to develop along and around this feature and its associated cold front. Rain chances (up to 50%) return early Mon, beginning in the western half of the CWA, then shifting east and north through the end of the period. We are not expecting severe weather, nor much thunder thanks to low instability, limited return flow, and weakening upper-level support. If any robust convection develops, it likely occurs over our waters and along the immediate coast where non-negligible CAPE and dewpoints reside. Overall, cool and wet conditions are forecast, with highs in the 50s generally north and west of Tallahassee and 60s to the east and south. Rain looks to clear our entire area heading into Tues morning under seasonably warm low temperatures (40s and 50s from northwest to southeast). .LONG TERM [Tuesday Through Saturday]... The aforementioned system departs our area on Tues and surface high pressure builds in the front`s wake. Global models (particularly the ECMWF) depict a southwesterly mid-to-upper level jet across the region, with an embedded vorticity anomaly riding the waveguide, which may force a few isolated showers on Wed, but PoPs are low (~10%). The bulk of the precipitation stays to the south and east of us. The GFS keeps an elongated area of vorticity over the southern states before a shortwave trough digs down, shunts the energy away and brings a reinforced shot of cool and dry air. The latter prompted forecast low temperatures to drop from upper 30s/low 40s on Wed to widespread 30s (but above freezing) away from the coast on Thurs. Mostly cool and dry conditions prevail through Thurs ahead of another cold front. Late next week, a broad longwave trough digs into the eastern US while bringing an extensive cold front to the CWA. It is too early to determine with high confidence what the convective potential will be, with the GFS suggesting an organized line of showers develop along the frontal boundary while the ECMWF shows more spotty precipitation. Included a return of rain chances (15%) on Fri into Sat to account for the possibility. High temperatures are expected to be mostly in the 50s outside of east Big Bend and the Suwannee Valley Tues-Wed, before rising to the 60s areawide prior to the cold front. We see low temperatures in the low 40s on Fri, followed by mid/upper 30s away from the coast and east Big Bend on Sat after FROPA. .AVIATION... [Through 00Z Monday] MVFR ceilings continue at all but ECP where clouds have scattered out. All remaining terminals will eventually do the same either by late tonight or early Sunday morning. Winds will become light and possibly variable at times through most of the TAF cycle. .MARINE... Favorable boating conditions are expected this weekend before cautionary winds and seas develop ahead of a cold front to start the work week. Showers with a slight chance of thunderstorms are forecast on Mon, where occasional gusts in excess of 20 knots will be possible, especially near any storms. Our western waters may briefly reach advisory levels that afternoon. Quiet weather follows after frontal passage, making for more tranquil conditions late Tues into Thurs. .FIRE WEATHER... Red flag conditions are not expected for the next several days. .HYDROLOGY... The following rivers remain in minor flood stage: 1) Withlacoochee River near Quitman - forecast to drop into action stage Sun afternoon 2) Ochlockonee River near Concord - forecast to drop into action stage tonight The Ochlockonee River near Havana - dropped into action stage this afternoon and the levels are forecast to continue dropping. Other area rivers remain elevated but most have crested and levels are dropping. Rain chances return on Mon but the forecast low amounts not expected to cause aggravation. The 7-day QPF are generally 0.25" or less. .SPOTTER INFORMATION STATEMENT... Spotter activation is not requested. However, spotters are always encouraged to safely report significant weather conditions when they occur (while following all local, state, and CDC guidelines) by calling the office or tweeting us @NWSTallahassee. && .PRELIMINARY POINT TEMPS/POPS... Tallahassee 33 55 41 61 50 / 0 0 0 20 20 Panama City 36 54 44 62 48 / 0 0 10 40 30 Dothan 31 51 37 53 44 / 0 0 10 40 30 Albany 32 53 38 55 46 / 0 0 0 30 40 Valdosta 34 56 42 63 51 / 0 0 0 10 20 Cross City 35 59 42 69 54 / 0 0 0 10 10 Apalachicola 37 55 47 64 52 / 0 0 0 30 20 && .TAE WATCHES/WARNINGS/ADVISORIES... FL...High Rip Current Risk until 5 AM EST /4 AM CST/ Sunday for Coastal Franklin-Coastal Gulf. GA...None. AL...None. GM...None. && $$ UPDATE...Barry NEAR TERM...DVD SHORT TERM...IG LONG TERM...IG AVIATION...Barry MARINE...IG FIRE WEATHER...DVD HYDROLOGY...IG