Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 12/01/17

Area Forecast Discussion
National Weather Service Columbia SC
608 PM EST Thu Nov 30 2017 .SYNOPSIS... A weak cold front will move into the area tonight. The front will stall and remain in the region through Saturday. The front will move off the coast Saturday night with high pressure moving into the region Sunday. A stronger cold front will approach by the middle of next week. && .NEAR TERM /UNTIL 6 AM FRIDAY MORNING/... A cold front currently moving into the Ohio and Tennessee Valleys will move into the forecast area overnight. Convergence associated with the front plus lift associated with the left exit region of an h25 jet supports a chance of showers. Coverage may be limited because of diminished moisture in an h85 westerly flow. Models begin taking the deeper moisture east by daybreak, so have pops gradually diminishing from west to east. Leaned toward the higher temperature guidance because of mixing associated with the front. && .SHORT TERM /6 AM FRIDAY MORNING THROUGH SATURDAY NIGHT/... Front pushes through the majority of the forecast area by early Friday morning. Any rainfall associated with the front should have pushed east of the area, and be diminishing as it moves out. High pressure will move north of the FA, with a northeasterly surface wind pattern shaping up. However, aloft an onshore flow pattern will develop. This may help to bring isentropic lift and just enough moisture back across the southernmost portions of the cwa Friday night into Saturday, and thus may cause a few scattered showers to form once again across the FA. Conditions should dry out once again by Saturday night. Temperatures Friday will be about 10 degrees cooler than previous day, with additional cooling expected to occur for Saturday. && .LONG TERM /SUNDAY THROUGH THURSDAY/... Sunday through what looks like Tuesday should be dry as high pressure will be over the majority of the area. Temperatures will once again rise to above normal levels Sunday through Wednesday. Models then indicate a digging upper level system will begin to carve out a deepening East coast trough beginning Wednesday into Thursday. Models do differ on the exact timing that far out, but a strong cold front is expected to push through the region near the end of the longer term period. A return to much colder air will occur behind the front. && .AVIATION /00Z FRIDAY THROUGH TUESDAY/... VFR conditions early this evening. Restrictions expected late tonight and Friday morning as a frontal boundary moves into the area and low-level moisture increases. Mainly mid level ceilings early this evening with lowering ceilings after midnight. The latest HRRR and LAMP guidance suggests MVFR strato-cu developing across the CSRA toward morning and spreading into central SC. Some upper level clearing after 10z may result in fog development but confidence low. Think MVFR ceilings dominate through 16z with a period of IFR possible. Lowest threat for significant restrictions appears to be OGB as low level moisture flux west of that terminal. Improving ceilings to VFR expected by afternoon with drying in the low levels. Winds will be light and variable. A cold front will move into the forecast area tonight bringing a chance of showers to the terminals. Coverage may be limited because of diminished moisture in an h85 westerly flow. The chance of showers was too low to include in the terminal forecasts at this time. MVFR or IFR conditions are expected to develop overnight due to lingering low-level moisture near the front combined with nocturnal cooling and drying aloft behind a shortwave trough. The pressure gradient associated with the front will be weak and expect continued light wind tonight. Models indicate visibilities returning to VFR by mid Friday morning with winds picking up slightly. Most of the model guidance shows IFR ceilings returning to MVFR by mid morning and remaining MVFR through the end of the 24-hr TAF period. EXTENDED AVIATION OUTLOOK...IFR or MVFR conditions may occur at times through Saturday associated with a front lingering near the area. It should be drier Sunday and Monday with ridging more dominant. && .CAE WATCHES/WARNINGS/ADVISORIES... GA...None. SC...None. && $$ SYNOPSIS...99 NEAR TERM...99 SHORT TERM...99 LONG TERM...99 AVIATION...99
Area Forecast Discussion
National Weather Service Cleveland OH
942 PM EST Thu Nov 30 2017 .SYNOPSIS... A large area of high pressure will move across the area tonight into Friday then persist into Saturday. A weak cold front will move across the region Saturday night. High pressure then reestablishes itself over the area for Sunday. && .NEAR TERM /THROUGH FRIDAY NIGHT/... Update...Removed slight chance pops nwrn PA. Also made minor hourly temp adjustments and adjusted overnight cloud cover up a bit in nern OH and nwrn PA based on satellite trends and 850mb moisture progression on RUC model. Original...Cold front is quickly moving eastward across the region and should be east of the County Warning Area by 23Z. Expect all the rain to move eastward with it. Skies will continue to clear from west to east but it will likely slow this progression across NE OH/NW PA with flow developing off of Lake Erie. High pressure will then take control of the area by Friday morning and persist into Friday night. Seasonal temperatures are expected through the the near term. && .SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/... High pressure will remain established over the area through Sunday, slowly drifting east Sunday night into Monday. This will keep conditions dry through this period, with temperatures slowly warming from the upper 40s for highs Saturday to the low to mid 50s by Monday. Dry conditions are expected through early Monday, but will keep slight chance/chance pops in the forecast Monday in advance of a cold front/deepening low. The models may be slowing down a bit with this system, which may end up leading to dry conditions through the entire daytime hours. && .LONG TERM /MONDAY THROUGH THURSDAY/... Much colder air still on tap for the long term as deep trough digs over the forecast area. Will see the coldest air of the season with highs only in the lower to mid 30s and lows in the lower to mid 20s. Models continue to differ somewhat on the precise timing of the approaching systems. Models continue to push first cold front across the forecast area Monday night into Tuesday. The ECMWF continues to be the faster of the 2 models pushing the initial front through by Tuesday morning. The GFS however develops a low on the boundary which stalls the front over the area into Tuesday night. GFS has the secondary arctic boundary catching up and pushing through Wednesday morning. The ECMWF on the other hand pushes the first front through Tuesday with a break then the arctic boundary going through Wednesday evening. For the forecast leaned toward ECMWF as it is much closer to continuity. Either way Lake effect snow develops in the snowbelt by Wednesday night as the 850mb temps plunge to -13c. How much snow will depend on which model you believe. The GFS has a ridge of high pressure build over the area Thursday night while the ECMWF has a secondary trough move across the forecast area Thursday night. For now used a model blend for temps and pops for Thursday. && .AVIATION /00Z Friday THROUGH Tuesday/... Post cold front clearing moving in across much of the area with the exception of nwrn pa and nern OH. Will continue with clear skies through the night and into Friday most areas. For KYNG will hold into a low VFR cig through the evening. For KERI will keep a low VFR cig through the night. Otherwise with all of the area having rain today and given that winds will be light and skies mostly clear, have placed mostly MVFR fog in TAFS overnight away from Lake Erie. OUTLOOK..Non-VFR may return Saturday night across NE OH/NW PA in the wake of a weak cold front. && .MARINE... A cold front will push east of Lake Erie by this evening. Winds will begin to shift to the northwest tonight, with small craft conditions expected from Cleveland east through most of the night. Winds will back off to 10 knots or less by Friday morning. High pressure will build across the region Friday and will remain in control through the weekend into early next week. Winds will remain southerly to westerly during this period, with some diurnal rises to near 15 kts or so. Winds will increase to 20 kts out of the south Monday night into Tuesday as low pressure deepens and moves into the central lakes, forcing a cold front across Lake Erie. && .CLE WATCHES/WARNINGS/ADVISORIES... OH...None. PA...None. MARINE...Small Craft Advisory until 9 AM EST Friday for LEZ146>149. && $$ SYNOPSIS...Mullen NEAR TERM...TK/Mullen SHORT TERM...Greenawalt LONG TERM...DJB AVIATION...TK/Mullen MARINE...Greenawalt
Area Forecast Discussion
National Weather Service Jacksonville FL
945 PM EST Thu Nov 30 2017 .UPDATE... Weak sfc high pressure is over the forecast region but a weak cold frontal boundary is sagging southeast across wrn NC to central AL through southeast LA. The front should move to near an Augusta GA to Ft Walton Beach FL line by 12z Friday. A shortwave trough is across the TN valley southwest to nrn LA and is generating some isolated to scattered patches of rain from west central GA southwest to the wrn FL panhandle. Satellite imagery shows partly to mostly cloudy skies now beginning to impinge on our northwest to western counties ahead of the shortwave trough. Otherwise...skies mostly clear with temps dropping into the 50s in some areas with light to calm winds. For the update...only minor changes to the min temps in the 50s to around 60...being a little warmer tonight than last night due to increased cloudiness. Have brought in a bit more precip to the nrn zones based on GFS and HRRR runs but staying with about 20 percent rain chances as QPF will be pretty light...probably at or below about .02" into early Friday morning. Prospects for areas of fog...some of it dense...still on track for mainly the east and primarily southeast zones where clouds will have less impact on cooling trends overnight. This is also where the SREF guidance has the highest fog chances...though lower chance than it was for last night. && .AVIATION...Prevailing VFR up until ~ 06z-08z but then anticipate VSBY conditions especially for the NE FL tafs with MVFR beginning. Chance of IFR or lower for CRG, VQQ and JAX toward early morning but put in a fairly short TEMPO window as mid level clouds will be moving in as well. conditions should improve to VFR all TAFS through the mid morning hours but with cigs around the 8-10k level expected. A light shower possible near SSI toward early morning but basically no sig wx impact. && .MARINE...Only minor edits for winds tonight that are at or below 10 kt. Seas forecast looks on track. Some patchy fog possible near/along the coast after midnight. && .PRELIMINARY POINT TEMPS/POPS... AMG 55 76 55 72 / 20 20 20 20 SSI 58 74 58 70 / 20 10 10 10 JAX 54 78 56 76 / 0 10 10 10 SGJ 53 75 58 74 / 0 0 10 10 GNV 52 78 55 77 / 0 0 10 10 OCF 54 80 56 77 / 0 0 10 10 && .JAX WATCHES/WARNINGS/ADVISORIES... FL...None. GA...None. AM...None. && $$ Shashy/23/McGinnis
Area Forecast Discussion
National Weather Service Melbourne FL
833 PM EST Thu Nov 30 2017 .UPDATE... Tonight...Surface high pressure ridge over north Florida will cause onshore flow to diminish, especially across our northern areas. There`s been a persistent north/northeast flow down the Gulf Stream this afternoon/evening, which has brought a few showers into the Treasure Coast. Expect a recent decreasing trend to continue as the gradient wind slowly eases and drier air filters down the peninsula, so any south coastal rain chances look brief. Mostly clear skies and light winds should promote fog development late tonight, especially across the north interior. Slight drying has occurred in the lower levels, but low temps will be a few degrees cooler, so expect at least patchy fog. The latest MOS guidance and NAM support fog formation, though the HRRR doesn`t develop any again (but it was wrong last night). Won`t be making any changes to the current forecast. Weak to light northerly flow, combined with a little drier air than 24 hours ago, will produce overnight mins a few degrees lower than this morning. Even the Treasure Coast should have mins a few degrees lower in the mid-upper 60s. && .AVIATION... Guidance continues to indicate a chance for late night fog across the interior terminals. Therefore have made no changes to the previous TAFs. Low level winds will be lighter early Fri morning, but still expect fog to diminish quite quickly in the 13-14z time period. && .MARINE... Tonight-Friday...Surface high pressure ridge across north Florida will produce a diminishing northeast flow, except northerly along the coast. Speeds already look 10 knots or less across the northern waters. 10-15 knots should hold on in the southern waters through the night. Seas up to 3 feet near shore and 4-5 feet in the Gulf Stream. && .MLB WATCHES/WARNINGS/ADVISORIES... FL...None. AM...None. && $$ FORECASTS...Lascody IMPACT WX...Ulrich
Area Forecast Discussion...UPDATED
National Weather Service Mobile AL
907 PM CST Thu Nov 30 2017 .DISCUSSION...See updated information for land and marine areas below. && .UPDATE...Regional radar imagery indicates that scattered to locally numerous rain showers associated with a shortwave trough have moved east and are mainly impacting south central Alabama as of 9 PM CST. Showers should gradually decrease in coverage through the late evening and overnight hours, but will leave a low rain chance in the forecast over the eastern zones overnight as residual moisture and weak lift remains in place across this portion of the region ahead of a slow moving cold front. Areas of dense fog will otherwise be the primary significant weather impact late tonight into early Friday morning. Surface observations and 11-3.9u satellite imagery indicate that areas of dense fog are already forming northwest of a Wiggins, MS to Camden, AL line right now where moist ground, a shallow saturated airmass in the low levels, and decreasing upper level clouds are favoring development. HRRR and SREF probabilities lend confidence that areas of fog will develop east-southeast with time across most of the remainder of the area through early Friday morning, so have issued a Dense Fog Advisory for the entire CWA through 9 AM Friday morning. Forecast updates have been sent. /21 && .MARINE...Areas of dense marine fog are likely to develop at least over Mobile Bay and the Mississippi Sound again late this evening through early Friday morning, so have issued a Dense Fog Advisory for these marine zones until 9 AM. /21 && .PREV DISCUSSION... /issued 613 PM CST Thu Nov 30 2017/ DISCUSSION...Updated for latest aviation discussion below. AVIATION... 00Z issuance...Scattered to numerous SHRA and associated localized MVFR to IFR cigs/visibility reductions will continue to push east of the I-65 corridor through the evening hours. Conditions are also now looking more favorable for the development of areas of fog and low ceilings across much of the region late this evening through Friday morning. IFR to LIFR ceilings are expected to develop, while visibility may also become reduced to LIFR or lower levels at times mainly after 03-06z. A light northwesterly to northerly wind returns this evening/late tonight following the passage of a weak cold front. /21 PREV DISCUSSION... /issued 356 PM CST Thu Nov 30 2017/ NEAR TERM /Now Through Friday/...Scattered to locally numerous showers will continue to move east across the Gulf coast this afternoon through the late evening ahead of an approaching cold front. The rain will end from west to east overnight as the front moves southward into the marine area Friday morning. No thunder is expected due to weak forcing and little instability. Rainfall amounts will be light, generally less than one-quarter of an inch. Ahead of the front, areas of fog will again be possible tonight. However, confidence is low in widespread dense fog due to the clouds and showers, but patchy dense is possible. Lows tonight will remain well above normal in the low to mid 50s. Clouds and rain will gradually clear the area Friday morning as the cold front moves into the marine area and high pressure builds in. Highs will climb into the upper 60s and low 70s. /13 SHORT TERM /Friday night Through Sunday night/...A broad upper ridge over the south central states expands northward across the remainder of the central states through Saturday night. The upper ridge amplifies while continuing eastward into the eastern through Sunday night. A large surface ridge centered over the interior eastern states persists through Saturday night, then weakens Sunday into Sunday night as a cold front advances across the Plains. This pattern will maintain a light northerly flow over the forecast area through much of the period before finally switching to a southeasterly direction Sunday night. Within the larger scale upper level pattern, am embedded shortwave trof advances across Texas Saturday night into Sunday then weakens as it moves to near the lower Mississippi river valley late Sunday night. At this time, this feature looks to weaken sufficiently so as to continue with a dry forecast through the period. /29 LONG TERM /Monday Through Thursday/...An evolving longwave trof advances across the Plains through Tuesday, which also has a positive tilt portending the potential for ejected shortwaves to advance downstream and across the forecast area. The large upper trof eventually amplifies further while continuing eastward into the eastern states through Thursday. A cold front advances from the Plains early in the period and moves through the forecast area Tuesday night, although there is some uncertainty with passage possible as early as early Tuesday evening or as late as Wednesday morning. Deep layer moisture increases to well above climatological normals ahead of the approaching front, with precipitable water values reaching around 1.8 inches immediately ahead of the front. These values are about 200% of normal for this time of year. Small pops return mainly to the western portion forecast area Monday into Monday night, then increase to chance to good chance on Tuesday as a series of ejected shortwaves move across the area ahead of the approaching front. Similar pops follow for Tuesday night with the passage of the front. Tuesday continues to be a challenging forecast period. There is some potential for CAPE values of 300 J/kg over the eastern portion of the area trending to CAPE values of near 500 J/kg almost becoming likely over southeast Mississippi. In addition, model soundings show a shallow cap near 800 mb which if overcome would result in increased CAPE values, perhaps an additional 300-500 J/kg. A veering profile is evident below 800 mb, but the latest guidance keeps helicity values near 100 m2/s2. Abundant low level moisture is present below the shallow cap, while dewpoint depressions of up to 20F exist further aloft and will significantly aid downdraft production for convection that breaks through the cap. Considering this environment, there still exists at least a low end potential for strong storms on Tuesday, and an isolated severe storm still cannot be ruled out, so will maintain current wording in the Hazardous Weather Outlook. That said, the potential now looks to be more over the western portion of the area but will continue to monitor. The remainder of the forecast period is another forecast challenge as well due to uncertainties regarding the strength and duration of an overrunning flow that continues across the forecast area in the wake of the front. This occurs as much cooler air flows into the forecast area with temperatures dropping into the mid 30s over much of the interior area Wednesday night, along with the 1300 meter 1000-850 mb thickness line dropping to just north of the coastal counties. Am thinking that drier air will work into the region to stop the precipitation before a change over to wintry precipitation could occur - but this will have to be closely monitored. So, will have good chance pops for the entire area on Wednesday, then pops taper off to dry conditions before temperatures drop off sufficiently to change the precipitation over to a mix. /29 && in the low levels .MOB WATCHES/WARNINGS/ADVISORIES... AL...Dense Fog Advisory until 9 AM CST Friday for ALZ051>055. Dense Fog Advisory until 9 AM CST Friday for ALZ056>060-261>266. FL...Dense Fog Advisory until 9 AM CST Friday for FLZ201>205. MS...Dense Fog Advisory until 9 AM CST Friday for MSZ067-075-076-078- 079. GM...Dense Fog Advisory until 9 AM CST Friday for GMZ630>632. && $$ This product is also available on the web at:
Area Forecast Discussion
National Weather Service New York NY
924 PM EST Thu Nov 30 2017 .SYNOPSIS... A cold front moves through late tonight. High pressure builds and will remain along the east coast through the beginning of next week. A frontal system will impact the area during the mid week period. && .NEAR TERM /UNTIL 6 AM FRIDAY MORNING/... Forecast is on track. Just minor adjustments to PoPs and hourly T/Td as temps are holding steady a bit longer than expected. Most areas should measure even though some values may only be a hundredth or so. Otherwise, models in good agreement in handling upper shortwave and sfc cold front tonight. Upper shortwave moves across the area tonight, with upper jet passing well to the north. Lift is weak, and moisture is lacking for any significant showers. Expect a brief line moving through with best chance for light measurable remaining across the NW zones, with some weakening as the line moves east ahead of the cold front. Pcpn should start to clear NW zones 3-4Z, and SE CT and Eastern LI by 10-11Z. Any qpf remains under a tenth of an inch, with minimal amounts expected closer to the coast. HRRR simulated radar reflects this timing. Temps should fall toward morning behind the front. Lows likely range from the middle 40s coast/NYC metro to the lower 30s by daybreak after the showers pass inland. Followed a blend of the MAV/MET and ECS guidance. && .SHORT TERM /6 AM FRIDAY MORNING THROUGH FRIDAY NIGHT/... Shortwave passes in the morning with ridge building behind. Plenty of sunshine is expected, with perhaps a few high clouds encroaching from the west Friday night. Temps a MOS blend with highs in the 50 to 55 degree range after weak CAA ends. NW winds pick up as the pressure gradient tightens, and gusts 20 to 25 mph are possible for a few hours between the front and building high. At night, lows will range from the lower 20s to the upper 30s as north winds abate and skies remain mostly clear, allowing radiational cooling to take place late. && .LONG TERM /SATURDAY THROUGH THURSDAY/... Zonal flow at the start of the long range period will give way to a much more amplified pattern with a full latitude trough impacting the area by the middle of next week. With a surface high centered over the east coast on Saturday and Sunday, dry and seasonable conditions are expected for the weekend. A shortwave passing to the north on Sunday will result in an increase in cloud cover during the afternoon, but with little moisture to work with, this is expected to be the only impact. The high begins to move offshore on Monday as the flow aloft amplifies with an upper ridge building along the east coast in response to a trough digging into the western U.S. Models remain in generally good agreement with the idea of the associated surface low and cold front progressing across the central CONUS on Monday before impacting the local area during the mid week period, but differences in the timing and evolution of this system remain. The ECMWF continues to advertise a faster frontal passage, bringing rain into the area during the day on Tuesday, while the GFS keeps the majority of the area dry until late Tuesday night. Given the uncertainty, continued with chance PoPs for much of the day on Tuesday into Wednesday before drying the area out behind the system on Thursday. Another complication is how far east of the area the front is able to progress on Wednesday/Thursday, as models continue to indicate the potential for a wave to develop along the front late in the period, which could prolong any precipitation. Temperatures on Monday will be near normal before rising above normal on Tuesday and Wednesday as southwesterly flow increases ahead of the front. Temperatures behind the front on Thursday will be near to a few degrees below normal, in the mid 40s. With strong warm air advection ahead of the front, the majority of the precipitation with the mid-week system is expected to fall in the form of rain, although a few snow showers or a rain/snow mix is possible north and west of NYC on Thursday as the precipitation comes to an end. && .AVIATION /02Z FRIDAY THROUGH TUESDAY/... A cold front moves across the region late tonight followed by high pressure for Friday. Some pockets of stratus around 2500 ft are possible ahead of approaching showers, but should not prevail. Otherwise, showers will quickly move through tonight from west to east. They should only last for a few hours. After the showers end, MVFR ceilings around 3000 ft are expected before a return to VFR before day break. Increasing southerly flow under 10 kt will gradually veer to the SW-W after midnight and then NW by early Friday morning. Timing of wind shifts may be off 1-2 hours from forecast. Gusty NW flow is expected late Friday morning into the afternoon. .OUTLOOK FOR 00Z SATURDAY THROUGH TUESDAY... .Fri Night-Mon...VFR. .Tue...MVFR possible in showers. && .MARINE... South winds increase ahead of a cold front tonight. Speeds of 15 to 20 kt are possible, especially on the ocean. Then winds shift around to the NW late tonight/Friday morning. Speeds remain around 15 kt with gusts around 20 kt. A few gusts could approach or reach 25 kt, but feel this will be brief. As such, no headlines planned after collaboration with surrounding offices. NW/N winds diminish Friday night as high pressure approaches from the west. Seas on the ocean remain 4 ft or less per guidance, and 2 ft or less on the non ocean waters surrounding Long Island. Quiet conditions are expected on the waters this weekend into early next week as high pressure remains in place along the east coast. Winds will begin to increase during the day on Tuesday as southwesterly flow increases ahead of an approaching cold front, with gusts approaching SCA criteria late. In addition, seas on the ocean waters will increase to 5 ft by Tuesday afternoon. && .HYDROLOGY... No significant hydrologic impacts are expected. && .EQUIPMENT... NOAA Weather Radio Station KWO-35 operating on a frequency of 162.55 mHz in New York City is OFF THE AIR for an extended period of time. See our headline news on the web ( && .OKX WATCHES/WARNINGS/ADVISORIES... CT...None. NY...None. NJ...None. MARINE...None. && $$