Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 11/15/18

National Weather Service Eureka CA
332 PM PST Wed Nov 14 2018 .SYNOPSIS...The very dry late fall continues with mild afternoons and chilly nights. Areas of smoke and haze will mix with a few high clouds, dimming the otherwise sunny skies. Dry weather will persist through the weekend while rain chances improve toward Thanksgiving. && .DISCUSSION...The RBG Cloud Phase Distinction product off of GOES 16 has been especially useful the past few days to display the differences between the mix of high and mid-level clouds, localized coastal stratus, and layers of smoke across northwest California. The smoke aloft and high clouds have clearly thinned or cleared out across much of northwest California, but smoke and haze has settled in closer to the surface, with poorer air quality along some of the valleys and especially the north coast compared to yesterday. Unfortunately while a passing trough has helped clear the layers of smoke aloft and allow for more daytime heating across inland areas, boundary layer winds remain very light. HRRR smoke modeling points toward some subtle improvement, so latest thinking is that the air quality may improve slightly and should not become any worse. However, surface winds still look very light on Thursday, with the stronger northerly gradient staying offshore, so expect some smoke and haze to continue to hang around, especially the farther south one is from the Oregon border. The other short-term questions will be stratus along the coast, and any need for frost advisories tonight. With some warmer temperatures and somewhat higher dewpoints along the coastal plain,in areas that are still officially in the growing season, slightly milder lows should be expected tonight, so have held off on any frost advisories. Meanwhile stratus has shown up along portions of the immediate Mendocino coast, while the north coast is still `clear`. Some hi-res guidance points toward shallow fog potential late tonight, particularly around Humboldt Bay, but expect that it will be fairly localized and short-lived heading into Thursday morning given the latest trends. Thursday night into Friday morning may offer more of a potential for coastal cloudiness from Cape Mendocino to Crescent City. Otherwise, sunny albeit hazy skies should continue into the weekend across our region. Temperatures will vary little through the weekend, with highs continued in the mid 60s to low 70s inland, and upper 50s to low 60s at the coast. A wetter pattern may finally arrive late next week, though some model guidance hints at enough of a threat that we have a slight chance of rain in the forecast starting on Tuesday. /AAD && .AVIATION...Lingering smoke from distant wildfires continues to slightly obscure visibilities at most area terminals today, although generally only to around 4 miles at worst. Gradual improvement in that regard can be expected overnight tonight and Thursday as northerly winds increase. Otherwise, low stratus has remained offshore as of late afternoon and terminals are generally unaffected. Late tonight, there are indications that very shallow low stratus and fog may develop along the immediate coast, potentially impacting both ACV and CEC. Given the extremely shallow nature of the moist marine layer, confidence is very low regarding this development. Flight categories along the coast will likely be boom or bust overnight and tomorrow morning, either remaining clear and VFR (lingering smoke notwithstanding), or tanking to LIFR with potentially 1/4 mile visibilities in the areas that fog develops. Skies should clear tomorrow afternoon, but higher confidence exists that more will develop tomorrow night. /BRC && .MARINE...While moderate northerly winds will develop across the offshore waters overnight (with light southerlies along the immediate coast due to a flow reversal), the more impactful development will be the arrival of a building westerly swell Thursday morning. While the aforementioned northerlies may push wave heights to a steep 6 or 7 feet overnight, the building swell tomorrow morning will cause seas to climb to around 11 or 12 feet. These conditions will last Thursday morning through generally Friday morning, and wave heights will gradually subside Friday. For the remainder of the weekend and through mid week, generally light and somewhat variable winds will prevail, and seas will remain dominated by a modest northwest swell. There are some indications that stronger southerlies and additional northwest swells may arrive later in the week, but confidence is very low beyond mid-week. /BRC && .EKA WATCHES/WARNINGS/ADVISORIES... CA...None. NORTHWEST CALIFORNIA COASTAL WATERS...Small Craft Advisory from 4 AM Thursday to 4 AM PST Friday for PZZ470-475. && $$ Visit us at Follow us on Facebook and Twitter at: For forecast zone information see the forecast zone map online:
Area Forecast Discussion
National Weather Service Indianapolis IN
944 PM EST Wed Nov 14 2018 .UPDATE... The NEAR TERM and AVIATION sections have been updated below. && .SYNOPSIS... Issued at 349 PM EST Wed Nov 14 2018 Dry weather will continue for a few more hours, but moisture is quickly building into the southern portions of central Indiana as a low pressure system moves closer to the Tennessee Valley. The system will bring wintry precipitation to all of central Indiana tonight into tomorrow. Snow and ice accumulations will make the Thursday morning commute hazardous. The system will then exit Thursday evening, and dry conditions will then prevail into the weekend. At that point, a cold front will bring the next chance for light snow and rain showers over the weekend. && .NEAR TERM /Rest of Tonight through Thursday Evening/... Issued at 944 PM EST Wed Nov 14 2018 Added more sleet to the forecast this evening as reports come in of predominantly sleet across the south. Some snow and light rain/freezing rain is also falling. Tweaked PoPs but the overall trend looks good, as the initial edge of radar echoes isn`t reaching the ground due to the dry low levels. Warm surge of air aloft still looks to impact the southeast forecast area the most per the latest RUC analysis and forecast. Thus for now have made no significant changes to ice/snow amounts. Will continue to monitor closely. Previous discussion follows... Current water vapor satellite shows an area of low pressure rotation over southern MO/northern AR, which will be the focus of the near and short term periods. The imagery also shows an influx of moisture into southern Indiana. So, the dry conditions will only continue through the evening hours before the air column becomes saturated and precipitation starts falling. Depending on how quickly the lower levels saturate and the exact start time of the precipitation will make a big difference in precipitation type with this system. Initially, there could be some light snow showers if the lower levels are able to saturate before Thu 00Z. But, if precipitation starts any later than that, precipitation could quickly change to a wintry mix of snow, sleet, and freezing rain as forecast soundings trend toward a warm nose in the mid levels. By midnight though, that wintry mix should be the predominant precipitation type through Thursday morning. As temperatures warm even further through the day on Thursday, freezing rain and rain will become the prevailing precipitation types through the remainder of the storm system. Due to the increase in warmer air aloft, snowfall totals have been reduced a bit and ice accumulations have been increased. So, latest snow totals are now trending toward less than an inch across the southeastern third of the forecast area to 1 to 1.5 inches over most of the area, and up to 3 inches across the far western counties. Meanwhile, ice accumulations are now trending closer to a tenth of an inch across the southeast quadrant, then gradually decreasing northwestward. As the system pushes east/northeastward on Thursday, precipitation chances will diminish from west to east with the western counties dry by Thu 23Z. Elsewhere, light rain and freezing rain will linger across the eastern counties until Fri 06Z. After that, precipitation should be out of the entire forecast area. && .SHORT TERM /Thursday Night through Saturday/... Issued at 349 PM EST Wed Nov 14 2018 After Fri 06Z, the aforementioned system will quickly move off to the northeast U.S. and dry conditions will return for most of the short term period. In addition, weak warm advection will bump daytime highs up a bit on Friday and Saturday into the upper 30s (north)to low to mid 40s (central and south). Saturday, precipitation chances will start increasing again from the northwest as a cold front approaches central Indiana. Precipitation will initially start as rain, then transition to snow, but accumulations will be minimal. && .LONG TERM /Saturday night through Wednesday/... Issued at 255 PM EST Wed Nov 14 2018 The extended timeframe begins with the forecast area under the influence of a broad upper trough aloft and a frontal boundary at 850mb across the northern portion of central Indiana. The main weather- maker during the extended portion of the timeframe rest with the approach of an upper trough rotating through the broad upper cyclonic flow. The GFS swings the effects of this system through a bit faster than the ECMWF solution. Because of this disagreement, decided to stick close to the regional initialization blend which trended toward the slower ECMWF solution. A slight chance for snow across the northern half of the area is in place to start the timeframe. Then precipitation chances increase and overspread the region during the day on Sunday into Sunday evening...with precipitation coming to an end from northwest to southeast Sunday night. Snow to start gives way to rain over much of the area on Sunday as temperatures warm. The northwest portion of central Indiana looks to see rain mix with snow Sunday afternoon before much of the area returns to all snow Sunday evening. If any accumulations were to occur...they look to be light. Monday looks to be the coolest day of the extended with highs from the middle 30s to near 40 degrees. Then a gradual warming trend takes root with highs on Wednesday from the lower 40s north to near 50 degrees south. && .AVIATION (Discussion for the 150300Z TAF Update)... Issued at 944 PM EST Wed Nov 14 2018 Lowered the ceiling (still VFR) to reflect current trends. Also brought in some light sleet earlier based on latest observations and radar trends. Previous discussion follows... Poor flying conditions are expected to develop by overnight and will persist through Thursday. A wintry mix will fall overnight into Thursday morning. Precipitation should take a while to reach the ground at the TAF sites this evening with a dry low level atmosphere. Precipitation will fall overnight into the early daylight hours of Thursday, then diminish. Looks like warm air aloft will create a mix of freezing rain and sleet overnight at KIND/KBMG, with mainly snow/sleet at the other sites. Confidence remains low at the moment on timing of when sleet or freezing rain will be predominant, so put them both in all night where needed. Colder air working in Thursday morning should allow precipitation to change to all snow, then perhaps to rain as temperatures warm up later in the morning. && .IND WATCHES/WARNINGS/ADVISORIES... Winter Weather Advisory through 7 PM EST Thursday for INZ021-028>031- 035>049-051>057-060>065-067>072. && $$ SYNOPSIS...TDUD NEAR TERM...TDUD/50 SHORT TERM...TDUD LONG TERM....MRD AVIATION...50
Area Forecast Discussion
National Weather Service Northern Indiana
608 PM EST Wed Nov 14 2018 .SYNOPSIS... Issued at 401 PM EST Wed Nov 14 2018 Clouds will continue to spread over the region ahead of an incoming area of low pressure. Clouds will provide some insulation overnight to promote lows in the upper 20s. Snow spreads in from the south early Thursday morning, which can result in some slippery travel conditions for the morning commute. Through Thursday, freezing rain and sleet can mix in at times as temperatures warm above freezing. Precipitation comes to an end Thursday night. For the extended forecast, below normal temperatures and couple of weak passing disturbances will be monitored. && .SHORT TERM...(This Evening through Thursday) Issued at 318 PM EST Wed Nov 14 2018 Latest water vapor imagery and RUC analysis depicting deep closed low over Arkansas this afternoon. Surface analysis showing inverted trof associated with upper low extending from the eastern gulf coast up into the Tennessee valley while high pressure was still centered over the southern great lakes. Upper low expected to lift northeast into southern Illinois tonight which will have main surge of low level WAA displaced east of our area. Resulting forecast soundings suggesting isothermal layer near 0C in the low levels which will complicate precip type. Northern edge of precip will reach the southern CWA after midnight tonight and begin as primarily snow as good surface based cold layer initially should have any partial melting changing back over to snow...with just a possible mix with sleet. Surface temperatures expected to hover at or slightly above freezing during the daytime hours and road surface model indicating temperatures in mid-upper 30s and diurnal timing would also trend surface temperatures more above freezing as the event unfolds Thursday so plan for now is to hold off on any headlines. Upper low slides east along the Ohio valley Thursday afternoon leaving deformation axis moving across our area and will have snow/rain chances continuing through the end of the day. && .LONG TERM...(Thursday Night through Wednesday) Issued at 318 PM EST Wed Nov 14 2018 System quickly exits to the east Thursday night and despite lingering cyclonic flow winds expected to maintain a southerly component to the westerly flow and limit any lake effect potential for our area. Surface ridge axis will extend from the gulf coast up through the Ohio valley and provide quiet weather for Friday. Pattern flattens somewhat and brings a couple of weak systems through region over the weekend. Generally quiet weather pattern beginning next week with temperatures continuing well below normal. && .AVIATION...(For the 00Z TAFS through 00Z Thursday Evening) Issued at 601 PM EST Wed Nov 14 2018 VFR conditions through 10Z - KFWA and 14Z - KSBN. Cigs lower quickly after that time as the northern edge of the system overspreads the region. As precipitation forms and increases in coverage...visby will drop as well to between 1 and 3 miles. The greatest challenge will be timing the transition from snow/sleet/rain. With the warm layer overrunning the near to sub freezing surface temperatures expect that there will be a period of sleet and possibly freezing rain during the early morning 12-16Z...especially at KFWA. The warm air will surge north and shift eastward throughout the day and this will favor a rain/snow mix for KFWA. KSBN expected to remain cold enough to keep precipitation all snow for most of the day. Easterly winds will pick up during the day...especially KFWA and east. && .IWX WATCHES/WARNINGS/ADVISORIES... IN...NONE. MI...NONE. OH...NONE. LM...NONE. && $$ SYNOPSIS...Brown SHORT TERM...JAL LONG TERM...JAL AVIATION...Lewis Visit us at Follow us on Facebook...Twitter...and YouTube at:
Area Forecast Discussion
National Weather Service Chicago/Romeoville, IL
906 PM CST Wed Nov 14 2018 .UPDATE... 906 PM CST No big changes planned for the forecast this evening. Current forecast has large deformation shield of snow spreading north into our southern CWA late tonight then marching slowly north through our CWA Thursday morning. Weakening forcing and the encountering of dry air suggest that this precip should be on a weakening trend as it lifts north of I-80. Secondarily, several models have been keying in on a developing mid level f-gen band supporting a developing band of precip (mostly snow) midday through late afternoon Thursday over portions of northeast IL. Confidence in this mesoscale feature developing isn`t terribly high as there is a great deal of variability among the models. The 00z NAM is in the camp with much weaker F-gen band and subsequently no measurable precip in the afternoon and very little precip making it north of I-80. There are still reliable models (the 00z GEM & HiResARW) that still develop this f-gen driven band of precip, though both of those models are a bit farther north than earlier runs. Given the uncertainty, made no changes to tomorrow`s pops/wx, though if the drier models like the NAM pan out then our pops are significantly overdone tomorrow afternoon. Only other change was to bump up sky cover a bit tonight near the lake where some lake effect stratocumulus has developed and has been spreading inland a bit. Shouldn`t be a big deal, but does warrant a slight increase in sky cover. - Izzi && .SHORT TERM... 121 PM CST Through Thursday... Short term forecast focus centers around a round of accumulating snowfall late tonight into Thursday, with some uncertainty as to how far the precip shield will get, where any potential snow bands will set up in the afternoon, along with precipitation type/icing concerns mainly late tonight into early Thursday. High pressure is in place across the area this afternoon, making for seasonally cold but dry conditions. There is some lake induced stratocumulus cloud near lakefront areas, but low level flow will turn around to the southeast/south which should limit the inland extent of these clouds. Our next feature of interest is the closed upper level low across the Arklatex region. With the cold air in place, this low will bring significant accumulating snowfall downstate. The upper low will spread to the mid Mississippi Valley in downstate IL tonight, and then spread east through the Ohio valley on Thursday. This track will favor areas south for precipitation, but there is a nice trowal-like feature that will setup out ahead of this system. There is a decent precipitable water axis that will setup in the southeast lower level flow. Guidance is still suggesting a surge of precipitation later tonight into Thursday morning, though a weakening trend is noted as the precip shield spreads farther north. Blended forecast soundings suggest p-type should be mostly snow in our area, but there is a a narrow corridor across Benton/Newton/Jasper, possibly into Ford/Iroquois that could have some mixed precip per the RAP The NAM/GFS/EC are all less aggressive with this warm nose, thus will hold off on any advisory for light icing given confidence issues, but something for the evening shift to monitor. There are then hints that some additional snow bands will form in the later morning/early afternoon, possibly over portions of the Chicago area. This timing is not favorable for pavement accumulation, as surface temperatures should be above freezing, and outside the main band rain could mix in. But under the main band column cooling would support all snow should a single band set up, and some grassy accums would be possible. Low confidence on the exact placement of this. For our southern areas, Forecast amounts have not changed a whole lot from previous ones, but the daytime precipitation does appear to be more localized and tied to the deformation zone. Still advertising a 1-3" type wet snow for some areas. KMD && .LONG TERM... 121 PM CST Thursday night through Wednesday... Following Thursdsay`s system, the upper level flow will shift back to northwesterly. The current system across the Pacific Northwest will follow an active upper jet and quickly cruise into the area Thursday night. The main moisture axis/surface feature will pass across northern and central Lake Michigan. There is a sharp upper trough, and along the nose of the jet we could see some very light precip during this time frame, but feel like most areas will remain dry. If there is some precip, it could actually be freezing drizzle given a nice wave and a deepening low level moisture field, but limited deeper moisture. This does appear more likely north of our area, but something to watch. There will also be some breezy southwest to west winds out ahead of the low. The more active wave will follow on the heels of this one as the northwest flow strengthens, and a stronger upper trough gets carved out across Hudson Bay. This feature will bring cold/arctic frontal boundary back southward, bringing a reinforcing shot of cold air, along with the chance for snow Saturday morning. There are several factors going for quick hitting snow chances in the region during this time. The first being a strengthening upper jet just north of the area, a tightening frontal boundary, and a low amplitude shortwave. The frontal signal is strongest while the upper forcing is still modest, but the frontogenetic signal is strong enough to suggest a round of light snow can be expected. Models are still mixed as to how far south the frontal zone will be, but the most likely time period would be Saturday morning. Snow amounts would not be high given the fast moving nature of the upper wave, but brief moderate rates would be possible where the frontal zone is strongest. There is a chance for some lake effect snow in the afternoon/early evening, but confidence is still low on that. Cold and dry conditions follow, but there are hints of a small warmup at some point next week. KMD && .AVIATION... For the 00Z TAFs... VFR conditions through early Thursday morning with light, mainly easterly, winds. During the morning Thursday, some snow, possibly mixed with rain, is expected attempt to move north into the Chicago metro area terminals. However, low level dry air, could impede the northward progress some. There are a handful of high resolution forecast models that suggest a narrow, but more intense band of snow could develop right over the Chicago area late Thursday morning into Thursday afternoon. Confidence in whether the band materializes is not terribly high, and subsequently if it does, where it will impact becomes a question. Given the uncertainties, felt the previous TAF nicely conveyed the forecast scenario. - Izzi && .LOT WATCHES/WARNINGS/ADVISORIES... IL...None. IN...None. LM...None. && $$ VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE) FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT: WWW.FACEBOOK.COM/NWSCHICAGO WWW.TWITTER.COM/NWSCHICAGO WWW.YOUTUBE.COM/NWSCHICAGO
Area Forecast Discussion
National Weather Service Baltimore MD/Washington DC
924 PM EST Wed Nov 14 2018 .SYNOPSIS... High pressure will build over New England overnight as an area of low pressure develops over the Tennessee Valley. Another area of low pressure will develop along the Carolina coast early Thursday and move north towards Long Island Thursday night, while the high pressure center moves offshore. Another area of high pressure will build in from the Ohio Valley over the weekend. A cold front will likely approach from the Great Lakes early next week. && .NEAR TERM /THROUGH THURSDAY/... At 02Z, regional radar mosaic shows reflectivity returns in southern and southwest VA, with 02Z surface obs shows unknown precip (aka likley IP) in southwest VA at Hillsville KHLX. Across our CWA, surface winds have begun to veer, showing cold air damming beginning to setup. This will initiate, and then reinforce, cold air below the inversion which is evident at around H85 on this evening`s 00Z KIAD sounding. Very cold air associated with the surface high (-10C 925mb at KALY) which attm is building into New England, will continue to drain down the northeast corridor and then get locked in place east of the eastern continental divide. This sets up a solid mixed winter p-type event along and west of the Blue Ridge, where Winter Storm Warnings are already in place, denoting much higher confidence of at least a moderate, potentially high impact event in these warned locations. However, east of the Blue Ridge, there is less confidence of winter p-type, with the influences of the Chesapeake Bay and Atlantic, particularly east of Intestate 95. The NWP-progged upward motion and cold air aloft tomorrow morning is an area of concern, as vertical displacement of this colder air aloft with large UVV as evidenced by every NWP model tomorrow morning could promote a longer period of frozen precipitation tomorrow morning in the I-95 corridor, including Baltimore and Washington DC Metro Areas. Fortunately, Winter Weather Advisories are posted in these areas as well, and the only updates I have made to the forecast is bring the snow/sleet accumulations further east with around 0.5" accumulations early tomorrow morning in the metro areas, and up to 1-2 inches in the northwest suburbs Loudoun/West Montgomery/Howard/N Balt. The reasonable, 23Z HRRR p-type diagnostic has precip moving in around daybreak in DC Metro, starting off as sleet and rain, then changing over to snow/sleet for several hours tomorrow morning. The same scenario exists for the Baltimore Metro, but holding off until 7-9 am start time. The model then shifts everything to rain early in the afternoon in this region. With the road temps forecasts aoa freezing, this should inhibit accumulations on road surfaces, unless the magnitude of the precipitation can overcome the above freezing road temps. This would be the reasonable worse case scenario, and even with this scenario, modeled road temps rise aoa 40F early afternoon in the Balt/Wash corridor. Bottom line attm is that it is likely that freezing and frozen will impact the Thursday morning rush hour, and while it likely won`t cause accumulation on road surfaces, it will be the first winter precip of the season and contribute to some shock and awe. West of the Blue Ridge, confidence is much higher for an extended 24-hour freezing/frozen p-type event lasting through Thursday night. Difficult to come up with high confidence specifics as to the mix/magnitude of p-type west of Blue Ridge, but the 90 percentile for freezing rain has well over 0.5 inches there, approaching 1.0 inch glaze accumulation in the central Shenandoah Valley and surrounding terrain. I have higher confidence with higher elevations aoa 2kft, as a major freezing rain event could be unfolding tomorrow along Skyline Drive and the eastern Continental Divide, including the Spruce Knob region. I also have concerns about moderate-to-heavy rainfall on Tuesday leading to isolated flooding due to rapid runoff, as vegetation has been killed off by freeze over the past couple of weeks. Areas most prone for runoff flooding will be southern MD, Prince Georges County/Upper Marlboro, and Anne Arundel. && .SHORT TERM /THURSDAY NIGHT THROUGH FRIDAY NIGHT/... A second low will develop over North Carolina on Thursday and strengthen through the day as it moves northeast under a coupled upper level jet. Meanwhile, an upper low will push northeast toward us from the south-central US. High pressure over New England will keep damming of cold air going over the western portions of the forecast area, while some cold air erosion looks likely east of the Blue Ridge by afternoon. Thus, have sleet/rain along and east of I-95 transitioning to plain rain through the day, with snow/sleet/freezing rain between the Blue Ridge and I-95 changing to sleet/freezing rain and then rain very late. From the Blue Ridge west, cold air likely gets stuck, so am keeping temps at or below freezing all day with snow/sleet/freezing rain transitioning mainly to sleet/freezing rain. Potential for significant snow and ice exists given the favorable synoptic set-up for cold air and heavy precipitation. Caveats to this solution include prolonged periods of sleet, the fact that heavy freezing rain is less efficient at accreting, and that much of the precipitation will fall while there is solar insolation. However, within the warned area, it is important to note that hazardous/wintry precipitation will be falling most of the day and into the evening with temperatures near or below freezing. Given the antecedent warm conditions, accumulations will likely be greater on grassy and elevated surfaces, as well as any areas which are typically shaded. Even where precip is mainly rain, the hazard of heavy rain and potential flooding will exist. See the hydro section below for more details. The surface low quickly lifts northeast Thursday evening, with a mid-level dry slot working in around the low to our west. Therefore precipitation will likely turn to light rain/drizzle, (freezing drizzle where surface temperatures remain AOB 32). Later in the evening and overnight, wraparound moisture associated with the passing upper low will bring a final shot of precipitation, which would initially be rain/freezing rain, but could end as a period of snow. Any accumulating snow is most likely over the mountains. Temps will likely be fairly steady Thursday night. Friday into Friday night, the system heads further away and we have a comparatively mild westerly flow settling across the region. Temps will actually be noticeably milder on Friday after the clouds break, with highs in the mid 40s to lower 50s. Lows return near or below freezing Friday night with high pressure in control. && .LONG TERM /SATURDAY THROUGH WEDNESDAY/... The long term period will start out with a weak ridge of high pressure at the surface and zonal flow aloft. This will lead to mostly sunny skies on Saturday, with temperatures maxing out in the upper 40s to near 50. Cloudier, but still dry conditions are forecast for Sunday, with temperatures once again reaching into the upper 40s to around 50. A cold front will progress through the area on Monday as a vigorous shortwave trough traverses the Great Lakes Region. With the main forcing for ascent associated with the trough displaced well to our north and limited moisture ahead of the cold front, any precipitation is expected to be light and mainly confined to upslope favored areas to the west of the Blue Ridge. High pressure will move back in for Tuesday, resulting in quiet weather conditions and below normal temperatures with highs in the 40s. && .AVIATION /02Z THURSDAY THROUGH MONDAY/... Clouds will lower as precipitation arrives late tonight towards dawn for the major terminals. Mainly rain expected at DCA (though there could be a period of sleet and snow), with more of a mix of rain/ice/snow at the other terminals. MRB is likely to be the snowiest and iciest, though temperatures could persist very close to freezing at CHO, BWI, and IAD into the midday to afternoon hours. Cigs and vis also likely to be significantly restricted on Thursday (IFR to LIFR), even where it is just plain rain. Low level wind is possible, although the surface gradient may preclude it from reaching criteria. Conditions improve later Friday night with VFR returning Friday as the system pulls away. Conditions continue VFR Friday night. VFR conditions are expected through the weekend into early next week. && .MARINE... An increase in winds overnight as low pressure develops and approaches from the southwest. Therefore, a Small Craft Advisory remains in effect for the middle Bay and lower Potomac. Winds shift more northeasterly Thursday and increase potentially to 35 knots, with gales now up for the central Bay. As the low passes overhead Thursday evening, there will likely be a lull in the winds, but they will increase again as the low pulls away, so have left the headlines in effect. A Gale Warning could potentially be needed for all waters by Friday morning. Rain and fog, perhaps also some sleet, are hazards Thursday as well, though the weather will clear on Friday. Winds will gradually subside by Friday night as high pressure moves in. SCA level winds may be possible very early Saturday morning before winds relax as high pressure moves overhead. && .HYDROLOGY... A plume of 1.5+ inch PWs will be advecting toward the Mid- Atlantic Thursday on an anomalously strong 850 hPa easterly jet. Though PWs likely stay around 1-1.25 directly overhead, the very strong low-level moisture advection coupled with strong mid and upper jet dynamics will result in widespread moderate to heavy precipitation. In the I-95 corridor where precipitation is expected to fall as mainly liquid (and where 6-hr FFG is less than 1.5 inches), some isolated minor areal flooding instances could arise. Generally 1-2" QPF seems likely, but will be spread out over a long duration. Latest MMEFS/NWM forecasts have trended downward for streams and rivers, but some poor drainage flooding is certainly possible, especially where leaves are blocking storm drains. && .TIDES/COASTAL FLOODING... Increasing onshore flow overnight into Thursday ahead of an approaching coastal low will cause tidal anomalies to increase. Although tides will be near astronomical minimums, minor flooding is still possible for at least some areas along the tidal Potomac River and western shore of the Chesapeake Bay. && .CLIMATE... Here are the current rankings for wettest year on record (through November 13th): Washington DC area (DCA) 1. 61.33 inches (1889) 2. 60.83 inches (2003) 3. 60.09 inches (1878) 4. 58.17 inches (1886) 5. 57.54 inches (1948) 6. 57.38 inches (2018) 7. 54.29 inches (1937) Weather records for the Washington DC area have been kept at what is now Ronald Reagan Washington National Airport (DCA) since 1945. Precipitation records observed downtown extend the period of record back to 1871. Baltimore MD area (BWI) 1. 62.66 inches (2003) 2. 62.35 inches (1889) 3. 61.68 inches (2018) 4. 58.98 inches (1979) Weather records for the Baltimore MD area have been kept at what is now Baltimore-Washington International Thurgood Marshall Airport (BWI) since 1950. Precipitation records observed downtown extend the period of record back to 1871. Dulles VA area (IAD) 1. 65.67 inches (2003) 2. 59.05 inches (1972) 3. 58.09 inches (1996) 4. 57.65 inches (2018) 5. 55.43 inches (1979) Weather records have been kept at what is now Washington Dulles International Airport (IAD) since 1960. NOTE: All climate data are considered preliminary until reviewed by the National Centers for Environmental Information (NCEI). && .LWX WATCHES/WARNINGS/ADVISORIES... DC...Winter Weather Advisory from 4 AM to 1 PM EST Thursday for DCZ001. MD...Winter Storm Warning from 4 AM Thursday to 4 AM EST Friday for MDZ003-501-502. Winter Weather Advisory from 4 AM to 1 PM EST Thursday for MDZ013-014-504. Winter Weather Advisory from 4 AM to 4 PM EST Thursday for MDZ503. Winter Weather Advisory from 7 AM to 4 PM EST Thursday for MDZ004>006-011-505>508. VA...Winter Storm Warning from 1 AM Thursday to 1 AM EST Friday for VAZ025-503-504-508. Winter Storm Warning from 4 AM Thursday to 4 AM EST Friday for VAZ026>031-507. Winter Weather Advisory from 1 AM to noon EST Thursday for VAZ036>038-050-056. Winter Weather Advisory from 4 AM to 1 PM EST Thursday for VAZ039-051>055-502. Winter Weather Advisory from 4 AM to 4 PM EST Thursday for VAZ040-501-505-506. WV...Winter Storm Warning from 4 AM Thursday to 4 AM EST Friday for WVZ050>053-055-501>506. MARINE...Small Craft Advisory from midnight tonight to noon EST Thursday for ANZ532-540-542. Gale Warning from noon Thursday to 6 AM EST Friday for ANZ532>534-537-540>543. Small Craft Advisory from noon Thursday to 6 AM EST Friday for ANZ535-536. Small Craft Advisory until noon EST Thursday for ANZ533-534- 537-541-543. Small Craft Advisory from midnight tonight to 6 AM EST Friday for ANZ539. Small Craft Advisory from 6 AM Thursday to 6 AM EST Friday for ANZ530-531-538. && $$ SYNOPSIS...ADS NEAR TERM...Lee SHORT TERM...ADS LONG TERM...KJP AVIATION...ADS/KJP/Lee MARINE...ADS/KJP HYDROLOGY...LWX TIDES/COASTAL FLOODING...LWX CLIMATE...LWX
Area Forecast Discussion
National Weather Service San Francisco Bay Area
329 PM PST Wed Nov 14 2018 .SYNOPSIS...Smoke and haze continue to impact much of the Bay Area while dry and seasonable weather persists elsewhere. No big changes in the weather through the end of the work week with some signs of less smoke and slightly cooler temperatures over the weekend. Dry conditions persist at least through Tuesday with possible pattern change by the middle of next week. && of 2:56 PM PST Wednesday...Smoke from the Camp Fire continues to be one of the main impacts on Bay Area weather. Satellite showed another belch of smoke this morning that has worked its way down the Sac Valley and into the Bay Area. Gradients show a half millibar offshore from Sac to SFO with east winds blowing in the Delta and bringing the smoke westward into the Bay Area. Visibility is now less than a mile in Livermore with the East Bay indicating some of the poorest visibility. Hazy skies continue elsewhere with afternoon highs generally in the 60s with 70s for the Central Coast. Very dry conditions continue this afternoon with many sites reporting humidity values in the single digits including usually wet spots such as Big Sur coming in at 9% Day over day changes in the large scale weather remain minor with daytime highs in the 60s and 70s with fairly cool overnight lows from the mid 30s to mid 40s through the end of the work week. Million dollar question is how active the Camp Fire will burn the next few days. As was shown today with lighter winds and even light offshore flow the smoke will tend to drift towards the Bay Area until we get a shift in the large scale weather patterns. That may occur by this weekend as an upper low approaches the Southern California coast and some type of southerly flow may help to keep any smoke to our east. It should be noted that latest trends build a ridge over northeast California over the weekend that will keep warm and dry weather up there with a fairly strong low level inversion likely in place, not ideal for smoke dispersion. Long range forecast details regarding any rainfall next week continues to be watched. The 12 and 18z gfs deterministic runs have been discouraging and gone completely dry. Need to note that the ensembles still show a trough along the west coast Weds through Friday of next week. The ecmwf has a weak front on Weds and a second stronger storm by about next Friday. This is all still 7-10 days out so confidence remains low on details as we anxiously await a pattern shift. Until then mild and dry weather for at least another 6 days. && .AVIATION...As of 03:29 PM PST Wednesday...For 00Z TAFs. Much of the area continues to see reduced visibilities to MVFR, with isolated instances of IFR, due to smoke. Generally poor vis is expected to continue with slant range visibility issues persisting through the period. Light winds will continue through the period as well. Vicinity of KSFO...MVFR vis due to smoke with generally light winds. Slant range vis issues expected to persist. Latest HRRR smoke forecast does not suggest much change in smoke conditions through at least tonight. SFO Bridge Approach...Similar to terminal. Monterey Bay Terminals...VFR prevailing with periods of reduced vis to MVFR due to smoke. && of 02:26 PM PST Wednesday...Predominately light north to northwest winds across the waters through the end of the work week. Locally breezy winds will exist near coastal gaps and favored coastal jet areas. Light mixed swell today with a new northwest swell arriving tomorrow. && .MTR WATCHES/WARNINGS/ADVISORIES... .Tngt...None. $$ PUBLIC FORECAST: RWW AVIATION: AS MARINE: DRP Visit us at Follow us on Facebook, Twitter, and YouTube at:
Area Forecast Discussion
National Weather Service Paducah KY
611 PM CST Wed Nov 14 2018 .UPDATE... Issued at 611 PM CST Wed Nov 14 2018 Updated aviation discussion for 00Z TAFs. && .SHORT TERM...(Tonight through Friday night) Issued at 302 PM CST Wed Nov 14 2018 Current Winter Storm Warning and Advisories remain in effect "as is" at this time. Current GOES-E Satellite Imagery showing a well developed closed upper low near El Dorado Arkansas, with significant deformation aloft to the north and east. Even though temperatures over Arkansas range from upper 20s to lower 30s from north to south across the state, widespread observations of snow is being reported at this time, suggesting most of the layer aloft is at or below freezing at this time. Deeper layer moisture and lift advecting northward from northern Mississippi into West Tennessee are within a zone of enhanced lift, as depicted by the latest preferred RAP numerical model guidance. This zone is in a decent area for seeder-feeder ice nucleation and will continue to work into the Purchase/Pennyrile region of west Kentucky through Sunset. As the mid-upper level low continues to work along eastern Arkansas between 6 pm to 8 pm, we could see an increase in snowfall intensity and lowered visibilities (1-2 statute miles) over southeast Missouri/Purchase area of west Kentucky, into extreme southern Illinois. Do not expect much recovery in temperatures the rest of the afternoon and actually a drop to 1-2 degrees overnight into the upper 20s over southern Illinois and southeast Missouri. Expect to see these areas remain in snow most of the night. For southwest Indiana and the Pennyrile region of West Kentucky, a drop in moisture in the ice nucleation layer, along with warm advection ahead of the low will make for a sharp west to east gradient for snow versus wintry mix then to rain. At this point in time, the zone of wintry mix (sleet/freezing rain/snow) will be along a Cadiz to Henderson Kentucky line, with a transition to rain near an Owensboro to Elkton Kentucky line. The best forcing overnight will shift toward northern section of southern Illinois, with higher precipitation amounts expected there through at least 5 am CST. Anticipate the best snow accumulations between 10 pm and 4 am tonight further north into Illinois. Could see a significant loss of moisture for any further snow and sleet production through the mid-morning hours on Thursday as the upper low moves close to Mount Vernon, IL by 6 am. May still see some deformation snow over northwest sections of southwest Illinois and southeast Missouri through at least 8 am. This should reduce the overall precipitation over the WFO PAH forecast area, with some mix possible. Needless to say, it will be a little tricky overnight, as any mesoscale banding in the vicinity of upper low may enhance wintry precipitation amounts. Evening and overnight crews will monitor for any adjustments in amounts and locations. Should see some recovery on temperatures into the 40s on Friday, with some slight reduction over areas with deeper snow cover still on the ground. .LONG TERM...(Saturday through Wednesday) Issued at 302 pm CST Wed Nov 14 2018 Currently the only pcpn forecast in the extended forecast period was a post-cold-frontal event mainly Sun afternoon through Sun night, driven by mid level shortwave energy moving out of the northern Rockies. The medium range models were in reasonable agreement with the timing of the event, though the 12Z GFS seemed at least 12 hours ahead of the 00Z ECMWF/12Z CMC with the passage of the surface wedge of cold air, thus making it a colder solution overall. The initialization blend ended up with a fairly early cold fropa on Sat, so it fits for now. This light pcpn event may start out as a brief wintry mix Sun morning in the far northwestern edge of the PAH forecast area. Otherwise, rain can be expected during the day, moving in from northwest to southeast. However, much of western KY may remain dry during the daylight hours. By nightfall, as thicknesses continue to drop behind a cold front, a transition from rain to snow is expected, with a possible brief wintry mix in between. Snow amounts of up to a couple of tenths are expected at this time. In the wake of the aforementioned system, high surface pressure will prevail under general northwesterly flow aloft. Unseasonably cool temps are expected to continue with the coolest temps occurring on Mon. && .AVIATION... Issued at 611 PM CST Wed Nov 14 2018 A very dynamic situation will keep conditions in flux over the next 12 hours or so as an unseasonably strong early season low moves across the region. Conditions will deteriorate quickly this evening where they haven`t already, with MVFR/IFR conditions persisting through the night. Mainly snow is expected across western portions of the region (KCGI/KPAH). This may be mixed at times with freezing rain or drizzle due to the loss of ice nucleation. Further east (KEVV/KOWB), a mix of snow, sleet, and freezing rain is expected. Precipitation should trend towards very light snow on Thursday in the wrap-around on the back side of the low. Winds will back from north/east tonight to west/southwest on Thursday with the passage of the surface low. && .PAH WATCHES/WARNINGS/ADVISORIES... IL...Winter Weather Advisory until 6 PM CST Thursday for ILZ076>078- 082-083-086-087-089>094. Winter Storm Warning until 6 PM CST Thursday for ILZ075-080-081- 084-085-088. MO...Winter Weather Advisory until 6 PM CST Thursday for MOZ100- 107>112-114. Winter Storm Warning until 6 PM CST Thursday for MOZ076-086-087. IN...Winter Weather Advisory until 6 PM CST Thursday for INZ081-082- 085>088. KY...Winter Weather Advisory until 6 PM CST Thursday for KYZ001>022. && $$ UPDATE...RJP SHORT TERM...Smith LONG TERM...DB AVIATION...RJP
Area Forecast Discussion
National Weather Service Raleigh NC
1020 PM EST Wed Nov 14 2018 .SYNOPSIS... Cold high pressure will build across the Northeast tonight, while ridging southward in the lee of the Appalachians. Meanwhile, a pair of low pressure systems from the TN Valley to the northeastern Gulf of Mexico will consolidate while tracking northeastward across the Carolinas tonight, then rapidly deepen while tracking up the middle Atlantic and New England coasts Thursday night and Friday. && .NEAR TERM /THROUGH EARLY THURSDAY/... As of 1015 PM Wednesday... ...Flood Watch remains in effect through 700 PM Thursday... There are three principle forecast concerns tonight and early Thu, including 1) the already-headlined expectation of widespread, soaking rain - and flooding, 2) the possibility of very light freezing rain over the nw Piedmont, and 3) the probability of 35-45 kt wind gusts that may down trees in saturated soil early Thu. Mid-upr low centered near the MO bootheel this evening will deepen while tracking newd into srn IL by 12Z Thu, with strong and perturbed mid-upr flow over the Southeast and middle Atlantic, between the deepening low and a strong sub-tropical ridge over the w- cntl N. Atlantic. In response, significant acceleration of low-mid level flow, and associated strong 925-700 mb WAA and moisture transport, will promote the development and nwd expansion of widespread rain from both the current precipitation shield over the Southeast, and another that will blossom nwd from off the Southeast coast late tonight. At the surface, 1036 mb high pressure centered over the lwr Great Lakes and far sern Ontario will build across the Northeast, while ridging swd through the middle Atlantic, Carolinas, and GA. The (dry air) ridge axis --and minimum in surface dewpoints-- was analyzed at 02Z from ern PA sswwd across ern VA and nrn NC; and the models indicate this feature will continue to migrate wwd across cntl NC with an associated minimum in surface dewpoints in the upr 20s to around freezing pivoting into the favored CAD region/over the nw Piedmont, by 09Z. Observational trends support that data, as the surface dewpoint at RWI and RDU has fallen five degrees in the past five hours to 32 and 34 degrees, respectively, for example. This cold, dry air advection, is being masked by the widespread light rain/sprinkles that have been falling into it over the Carolinas and VA during to the past 24 hours. This ridge will get squeezed over wrn NC, as one cyclone analyzed at 02Z near CSV deepens while tracking into the lwr OH Valley, and a pair of other lows on the primary surface baroclinic zone from the nern GOM to just offshore JAX, consolidate while tracking to near CHS by 12Z Thu. Between the primary lows, there has been a gravity wave-like signal across the Carolinas in model guidance for a couple of days now, including most notably the NAM and HRRR today. Both show sharp pressure perturbations migrating through the simulated MSLP field to the nw of the consolidating coastal low, with associated max wind gusts around 40 or so kts spreading across cntl NC between 10-18Z. This surface trough and ongoing narrow precipitation band and sharp convergence axis, evident for several hours in FFC data over wrn GA, will be the one and area to watch for wave amplification and manifestation of a strong pressure fall/rise couplet and (isallobaric) surface wind response. In other words, if spurious winds/gusts become evident over n-cntl GA and wrn SC become evident by 06-09Z, then the likelihood of those traveling downstream in the subsequent 6-9 hours would increase confidence in such an occurrence of strong surface winds in cntl NC. Regarding the freezing rain threat, guidance, including the 00Z NAM, suggests the wet bulb freezing line will be draped from near HKY to MTV, near and just nw of Forsyth Co. between 08-13Z, with resultant surface temperatures hovering just above freezing over the nw Piedmont. As previous shifts have astutely noted, the magnitude of mid level warming characterized by 700-850 mb partial thickness nearing 1590 or so meters, combined with a wet and relatively mild mid-Nov ground, suggests very little freezing rain accrual potential; and any that does occur, would be most likely to occur (very lightly) in trees/power lines, with elevation away from the surface and into the cold nose. Lastly, a few elevated rumbles of thunder may occur between 12-15Z Thu, for weakly unstable parcels rooted above the very stable boundary layer. && .SHORT TERM /THURSDAY THROUGH FRIDAY NIGHT/... As of 320 PM Wednesday... Thursday and Thursday night: The widespread rain will continue through midday/early afternoon, becoming moderate to heavy at times as the coastal low tracks inland, up coastal NC. Some elevated thunder across the far eastern zones is also possible, as the NAM hints at 500 J/KG of MUCAPE east of I-95. Otherwise, any surface base convection should remain east of the surface low, along the immediate coast. Precipitation will then begin to taper off to drizzle Thursday afternoon and evening as drying aloft overtakes the area from the SW. Expect a very sharp NW-SE temp gradient with the cold air damming entrenched across the NW Piedmont, resulting in very little rise in temps on Thursday, while eastern areas will experience modest warming in proximity to the coastal low. Highs ranging from mid/upper 30s NW to upper 50s/lower 60s SE. Cold dry air advection in the wake of the low lifting up the Mid-Atlantic coast will lead to clearing overnight. Lows in the upper 20s/near 30 NW to mid/upper 30s east. Hydro/: With soils already saturated, along with area river and and streams already in flood, another round of widespread heavy rainfall of 1 to 2 inches will result in a heightened risk for additional flooding across central NC tonight through Thursday. By Friday morning, the upper-level low will continues to shift northeastward along the Atlantic Coast, with a period of more zonal flow aloft taking over. This will allow cooler air to advect into the area in the low`s wake, with a downsloping westerly/northwesterly wind helping to dry out the area. This will allow for gradually clearing skies and afternoon temperatures warming slowly into low to mid 50s. Overnight lows will settle again to near freezing across the north, with mid 30s prevailing across the coastal plain and sandhills. && .LONG TERM /SATURDAY THROUGH WEDNESDAY/... As of 320 PM Wednesday... SFC high pressure will build into the Mid Atlantic over the weekend as a slightly more progressive troughing regime begins to take shape late in the weekend. This will allow for a mostly dry sfc FROPA on Monday. With the area of subsidence in place, overnight lows will remain well below normal, while high temperatures will actually moderate slightly in the wake of the system. Expect highs generally in the 50s each afternoon with overnight temperatures dipping into the mid 30s across central NC through early next week. A reinforcing cold front may bring a better push of cold air and perhaps a few clouds into the region early on Monday, however, uncertainty remains in place in reference to overall timing and strength of this system. && .AVIATION /00Z THURSDAY THROUGH MONDAY/... As of 730 PM Wednesday... Dry air around 900 MB continues this evening with weak returns mainly across the western half of the CWA (towards KINT and KGSO). Rain will continue to spread into the region from the southwest this evening with widespread rain moving in after midnight. Ceilings will also fall below VFR around 8z if not earlier. Forecast soundings on the GFS and NAM show a time frame of more around 6z. Ceilings will then continue to further collapse to LIFR. Visibilities will also quickly fall down into IFR and potentially LIFR as heavier pockets of rain move overhead. Also in the morning hours, some freezing rain will be possible as forecast soundings show thermodynamic cooling occurring (mainly between 5 and 7 AM). Temperatures will rise above freezing everywhere (if any sub 32 degrees ends up occurring). Ceilings and visibilities will remain down through the TAF issuance though. During the day, widespread precipitation will continue and not come to an end until the afternoon hours. Winds will also be gusty with gusts up to 30 kts possible. Outlook: Gusty NW winds can be expected Friday, with VFR conditions otherwise. && .RAH WATCHES/WARNINGS/ADVISORIES... Flood Watch through Thursday evening for NCZ007>011-021>028- 038>043-073>078-083>086-088-089. && $$ SYNOPSIS...MWS NEAR TERM...MWS SHORT TERM...CBL LONG TERM...JM AVIATION...Haines
Area Forecast Discussion
National Weather Service Tampa Bay Ruskin FL
800 PM EST Wed Nov 14 2018 .UPDATE... A cold front moving southeast through the Florida Panhandle and eastern Gulf of Mexico is on track to push south into the Florida Peninsula overnight, with a robust squall line positioned ahead of the front, just now entering the coastal waters early this evening. Scattered to numerous thunderstorms are developing over the Florida Peninsula ahead of this storm, and are continuing to lift north through the forecast area this evening. Storms were a bit slower in developing this afternoon than were previously forecast, and HRRR and other short range models are showing a the squall line breaking apart as it approaches the coast overnight. As a result, the rain forecast for the overnight hours was dialed back slightly from what was previously advertised. Otherwise, the forecast looks on track, and no significant changes were needed for the evening update. && .AVIATION... Scattered showers and thunderstorms will continue to move north through the area overnight, causing periods of MVFR-IFR conditions. Widespread MVFR ceilings will spread across the area overnight as a cold front passes south into the area. On Thursday, periods of MVFR ceilings will continue throughout much of the day under breezy northwest winds. && .MARINE... Showers and thunderstorms will continue and winds will increase overnight as a strong cold front pushes southeast into the coastal waters. Winds are expected to reach advisory levels offshore overnight, and cautionary levels nearshore. Winds will turn to the northwest and then north behind the front tonight and Thursday, and will hold around cautionary levels. Winds will gradually subside Friday through the upcoming weekend as high pressure builds in from the northwest. && .Preliminary Point Temps/PoPs... TPA 68 70 50 67 / 50 20 0 0 FMY 71 77 55 72 / 40 20 0 0 GIF 68 73 46 68 / 40 20 0 0 SRQ 69 72 54 69 / 40 20 0 0 BKV 66 67 42 66 / 60 20 0 0 SPG 69 70 54 67 / 50 20 0 0 && .TBW WATCHES/WARNINGS/ADVISORIES... FL...High Rip Current Risk from 5 AM EST Thursday through Thursday evening for Coastal Charlotte-Coastal Hillsborough-Coastal Lee-Coastal Manatee-Coastal Sarasota-Pinellas. Gulf waters...Small Craft Advisory from 11 PM this evening to 5 PM EST Thursday for Waters from Bonita Beach to Englewood FL out 20 to 60 NM-Waters from Englewood to Tarpon Springs FL out 20 to 60 NM-Waters from Tarpon Springs to Suwannee River FL out 20 to 60 NM. && $$ UPDATE/AVIATION/MARINE...18/Fleming UPPER AIR...99 DECISION SUPPORT...99