Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 12/11/19

National Weather Service Wakefield VA
716 PM EST Tue Dec 10 2019 .SYNOPSIS... A cold front crosses the area this evening through tonight. High pressure returns late Wednesday through Thursday. Low pressure develops along the Gulf Coast Friday before approaching the area this weekend. && .NEAR TERM /UNTIL 6 AM WEDNESDAY MORNING/... As of 715 PM EDT Tuesday... Sfc cold front starting to push across far western portions of the local area this evening. Made minor adjustments to Pop/Temps through midnight, mainly lower pops along the coastal plain in the pseudo-warm sector with sct showers expected before midnight. A light rain or even drizzle across the west for the next few hours, before more appreciable moisture arrives late. Did get a little bit more aggressive with RA -> SN transition wording late. The past few HRRR runs and even the RAP doing better than the downscale NAM (Nam- Conest) this evening. Still, previous forecast looks good overall...with a very minor snow "event" expected across the area late tonight, if you could even call it that. Some light snow accumulation on elevated/grassy sfcs likely for the morning rush over far northern tier of the CWA, with the metro area, VA northern neck and lower eastern shore potentially seeing a very light accumulation on grassy sfcs before precipitation ends by mid- morning. As of 340 PM EST Tuesday... Late afternoon upper air analysis shows a large upper low centered over Hudson Bay, with broad troughing over the Plains/Midwest. The deep trough is positioned between two areas of upper ridging: one along the Pacific coast and another well off the SE CONUS coast. At the surface, strong low pressure was over Quebec/Newfoundland, with ~1029 mb high pressure over the Central Plains. A strong (trailing) cold front was draped from Quebec SSW through the central CWA to the ern Gulf Coast. A secondary push of colder air was located to the north and west of the initial boundary. There is an area of showers from srn VA to VA Northern Neck (along the initial boundary), but it is mainly dry across the NW Piedmont and over coastal/SE zones. Skies are overcast across the northwest two-thirds of the CWA, with partly-mostly cloudy skies over the SE half of the CWA. Temperatures are in the upper 50s-around 60F from the SW Piedmont-central VA-Dorchester County (MD). In contrast, it has warmed into the mid-upper 70s across coastal SE VA/NE NC (with low 70s across the northern part of Hampton Roads/the VA Ern Shore. As the initial boundary continues to cross the region this evening...the aforementioned area of showers will continue to move eastward. Have likely PoPs across ern zones (except for NE NC) through 00z w/ chc PoPs farther west. Not a whole lot of rain expected during the next few hours (mainly around 0.10" or less). The secondary (stronger) push of CAA arrives tonight, which will allow temperatures to drop rather quickly after 00-03z. At the same time (or perhaps a couple hours later), a stratiform area of light/moderate rain develops/moves over the area. This is due to (in part) a band of strong 850-700 mb frontogenesis that will become situated across the area behind the sfc cold front (as the mid/upper trough axis remains to our W). PoPs increase to 90-100% for all areas (except for the SE corner of the CWA) by 06z Wed. As the night wears on, low-level thicknesses continue to fall as sfc temperatures keep dropping. As a result, the pcpn is expected to mix with, then change over to snow in areas from the NW Piedmont to Dorchester County (MD) by 4-5 AM before potentially changing to snow in areas north/west of a FVX-RIC- SBY line by 5-7 AM. Cannot rule out a brief period of sleet during the changeover, given that guidance continues to hint at a warm nose between 800-700 mb across much of the area. Pcpn quickly tapers off from W to E from Wed AM-midday. PoPs decrease to 15-35% by 15z Wed. Not a whole lot of changes regarding forecast thinking. Generally have a dusting to 0.5" of snow across the NW Piedmont, VA Nrn Neck, and the Lower MD Ern Shore (w/ no accumulations elsewhere). Certainly could see a few locally higher totals (likely aob 1") if the snow comes down hard enough for an hour or two. Latest 12z/10 EPS probabilities for > 1" of snow have decreased to 10-20% across far nrn portions of the CWA. Temperatures will remain aoa freezing through the event, so not expecting much in the way of impacts. QPFs tonight-Wed are generally a few tenths of an inch. Clouds decrease across the west Wed aftn, while it remains partly cloudy across far SE VA/NE NC. Not much rise in temps given the clouds and CAA. Highs Wed will be in the low 40s in most areas. && .SHORT TERM /6 AM WEDNESDAY MORNING THROUGH FRIDAY/... As of 340 PM EST Tuesday... Strong (~1040 mb) high pressure builds toward the area late Wed-Wed night before becoming centered just to our N by 12z Thu. A secondary CAA surge is progged to arrive Wed night (though it does not appear as strong as it did yesterday). Nevertheless, expect lows in the low-mid 20s inland, while temperatures bottom out around 30F across coastal SE VA/NE NC (as light onshore flow persists through much of the night). The high becomes centered over New England Thu aftn before pushing east to the Canadian Maritimes by Thu night. Still cold on Thu with highs ranging from the upper 30s N to the mid- upper 40s SE. Upper troughing starts to deepen from the Midwest to the MS River Valley on Fri as low pressure develops along the eastern Gulf Coast. This will allow pcpn to move into the area from S to N on Friday as deep layer moisture/WAA increase across the area. Thus, will indicate increasing clouds but will continue to keep it mostly dry thru 12z Fri (as the latest GFS/ECMWF solutions continue to show pcpn holding off until later in the day). Lows Fri will likely occur around 06z before temperatures level off/rise a bit due to increasing clouds/WAA. Lows Fri morning range from the upper 20s across the Piedmont the low 40s in coastal SE VA/NE NC. Pcpn rapidly overspreads the area on Fri as the low tracks NNE to the ern Carolinas by late in the day. PoPs increase to 50-80% by aftn. This should be mostly in the form of rain, but cannot rule out a couple hours of light freezing rain across the NW Piedmont if the pcpn starts early enough. Will continue to advertise this in the forecast, but this should quickly change to rain by mid morning as temperatures rise above 32F. Quite a range of high temperatures on Fri, as models continue to hint at the development of an in- situ wedge. Forecast highs Fri range from the low 40s across the Piedmont to near 60F over SE VA/NE NC. QPFs from 12z Fri-00z Sat generally range from 0.2-0.5" (lowest NE/highest SW). && .LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/... As of 400 PM EST Wednesday... Short wave upper trough will develop across the southern Plain states Friday and move east into the Deep South. This will allow for an area of low pressure to form at the surface across the northern Gulf of Mexico. At the same time on Friday, a large area of high pressure will move off the New England coast and will allow the warm air to return to area ahead of the low pressure system. As the upper level shortwave moves northeast, the sfc low pressure will track northeast out of the Gulf of Mexico along the east coast. The center of the low pressure system will likely track just inland along the coast, across eastern VA, NC, and MD. Rain will overspread the area early Saturday morning as the low tracks over the area. The low pressure system will then continue to track northeast into interior New England and Quebec, giving the area a dry northwest flow for Sunday. Temperatures on Saturday will have a large range across the area. With temperatures climbing into mid 60s across the NC and VA coast, and Delmarva. While the cooler air will be trapped east of the mountain across the VA Piedmont with highs in the upper 40s. Sunday morning temperatures will be in 35-45 and highs in the low 50s with mostly sunny skies. Dry conditions will continue into Monday as a cold area of high pressure moves southeast across the Great Lakes Sunday night into Monday morning. High pressure will be centered over the area Monday with high temperatures on Monday in the mid 40s and lows Monday night in the low 30s. Models are indicating that another area of low pressure will develop in the northern Gulf of Mexico and track into the Mid-Atlantic Tuesday, bringing the next chance of rain, and possibly wintry precip for the onset of precip. && .AVIATION /00Z WEDNESDAY THROUGH SUNDAY/... As of 715 PM EST Tuesday... VFR conditions prevail early this evening across the sern terminals, while MVFR CIGs continue across northern terminals (RIC/SBY). A cold front will push across the area over the next few hours, with showers becoming more widespread overnight. While prevailing VSBYs likely remain VFR, brief MVFR (or even IFR) VSBYs will be possible in these showers. Showers likely continue through the evening...but there may be a few breaks in the rain through 04z. Behind the frontal passage, still expect deteriorating flying conditions, with CIGs falling from MVFR to IFR late tonight in addition to RA (VSBYs mainly between 2-4SM). Winds become NNW overnight, gusting to 15-20 kt along the coast late. There is an increasing chc that pcpn changes over to PL, then SN late tonight/Wed AM before ending at RIC/SBY. Not expecting much in the way of impacts from wintry pcpn, but maintained a mention of mixed pcpn in the TAFs for RIC/SBY (mainly from 09-14z Wed). Pcpn should stay in the form of RA at the sern terminals. Pcpn ends from W to E from Wed AM- midday (at the latest). IFR CIGs improve to MVFR Wed AM before rising to VFR/scattering out by aftn. OUTLOOK...High pressure builds into the area Wed night and Thursday, allowing VFR/dry conditions to return. Another area of low pressure brings rain and degraded flight conditions Friday through Saturday. && .MARINE... As of 220 PM EST Tuesday... Cold front will slowly cross the waters through this evening shifting winds from WSW to NW. Speeds avgg 10-20 kt prefrontal then some decrease w/ and shortly behind the front. Low level CAA kicks in by late this evening...through the overnight and Wed morning before waning. Due to the CAA...speeds to increase to 15-25 kt...w/ 30 kt possible(for a brief period) over the lower Ches Bay and the ocean. Winds diminish Wed afternoon. A second surge of low level CAA expected Wed night (that does appear to be a bit weaker than the first one tonight) before sfc hi pres finally builds over the local waters. That sfc hi pres drifts off to the NE Thu-Thu night. Lo pres begins to develop INVOF Gulf of Mexico Fri then tracks NNE near the mid-Atlantic coast by Sat morning which may result in increased winds and deteriorating wx conditions over the waters heading into the weekend. SCAs will be up for all of the waters except parts of the VA Rivers (though even those areas may have a brief period of near SCA conditions - winds gusting to 20 kt). SCAs to come down during Wed for the Ches Bay...sound and lower James River then will likely be needed again Wed night/early Thu. For the ocean...SCAs will be up into Thu morning (N) and through Thu afternoon (S) as seas will remain aoa 5 ft. && .CLIMATE... Record highs for today (12/10). RIC...79 in 2007 ORF...78 in 2007 SBY...73 in 1966 ECG...78 in 2007 && .AKQ WATCHES/WARNINGS/ADVISORIES... MD...None. NC...None. VA...None. MARINE...Small Craft Advisory until 1 PM EST Wednesday for ANZ632>634. Small Craft Advisory until 10 AM EST Wednesday for ANZ630-631- 638. Small Craft Advisory until 9 AM EST Thursday for ANZ654. Small Craft Advisory until 7 PM EST Thursday for ANZ656-658. Small Craft Advisory until 6 AM EST Thursday for ANZ650-652. && $$ SYNOPSIS...MAM NEAR TERM...ERI/MAM SHORT TERM...ERI/MPR LONG TERM...CP AVIATION...ERI MARINE...ALB CLIMATE...
Area Forecast Discussion
National Weather Service Boston/Norton MA
1031 PM EST Tue Dec 10 2019 .SYNOPSIS... A strong cold front crosses the region this evening, followed by colder temperatures with showers changing to a period of accumulating snow later tonight into Wednesday morning, especially south of the Massachusetts Turnpike where a significant impact may occur during the morning commute. Large high pressure will bring cold and dry conditions Thursday and Friday. Developing low pressure across the southeast U.S. will shift up the coast with the potential for periods of heavy rain Friday night into Saturday, possibly beginning as a period of light snow across interior Massachusetts. Drier and cooler weather returns Sunday into Monday. Another storm may impact the region next Tuesday with snow or rain. && .NEAR TERM /UNTIL 2 AM WEDNESDAY MORNING/... 1030 PM Update... Forecast remains on track with rain beginning to transition to snow across the higher terrain of MA. This process will occur in the next few hours across most of interior MA/CT, reaching eastern MA/RI by 3 or 4 AM, and the Cape by 7 AM. We still think this looks like a general 1 to 4 inches of snow across much of the region. Greatest risk for the higher amounts will probably be across portions of the northeast CT and Worcester Hills, as well as areas in the Foxboro/Sharon areas. The reasoning is better forcing aligning with a bit of elevation. May also see those higher amounts near the south coast, where potential for better banding/snowgrowth may occur. May see lower end totals, perhaps just a coating to 1 inch over portions of the CT River Valley especially in western MA where they are further removed from the forcing. Still looks like a narrow window, where very strong jet dynamics result in impressive 600-700 MB FGEN and snowgrowth. The limiting factor will be the shorter duration as drier air advecting into the region given WNW just off the deck. Regardless of exact accumulations, main concern is briefly moderate to heavy snow impacting the Wed AM commute in the Hartford, to Providence, to Worcester and Boston metro areas. Greatest concern will be across RI/SE MA where snow will persist into the late morning hours. && .SHORT TERM /2 AM WEDNESDAY MORNING THROUGH 6 PM WEDNESDAY/... 7 PM Tuesday Update: Incoming 18z guidance (NAM/GFS) and the RAP have come in a bit wetter QPF-wise and shifted ever-so-slightly NW than earlier iterations, especially in that 06-12z timeframe on I-95 SW of Boston on to Providence into south-central RI, on into the Cape. Some of which is almost double from its prior run. A good fraction of this ends up being rain as this is the window in which rain changes over, but I did opt to raise liquid- equivalent QPF by about a tenth of an inch or so across SE Mass/RI and a few hundredths higher N/W of I-95. That brings about an increase in snow accumulations by an inch to inch and half into SE Mass and on through RI, and less than a half-inch increase further NW of I-95/Mass Pike. These changes didn`t necessitate any changes to headlines. GFS continues to advertise an axis of mid-level frontogenetic forcing that shifts SE into the early Wed AM period. If that transpires, that FGen could organize some narrow snowbands into the I-95 corridor S of Boston, with moderate/heavy snow in them at times. Will defer any further adjustments until the 00z guidance comes in. Prior discussion follows... * Accumulating snow expected late tonight into Wed AM, with highest amounts south of the Pike * Significant impact to Wed AM Rush hour possible, especially across parts of NE CT, Rhode Island and Southeast MA Classic anafrontal wave develops later tonight as robust mid level shortwave digs into the Great Lakes with SW flow aloft across SNE. This will allow deeper moisture axis to set up across the region with impressive jet dynamics as right entrance region of 170-180kt upper jet moves across the region. Initially, around and just after midnight, ptype will be rain in the coastal plain with snow further in the interior. However, rain will flip to snow from I-95 corridor to the south coast from 06-09z and 09-12z for the Cape/Islands where a period of sleet is possible during the transition. Good synoptic scale forcing with some enhanced mesoscale forcing as band of mid level frontogenesis develops. Pinpointing the location of this banding potential is a challenge but latest guidance suggests it will be mostly south of the Mass Pike. Also, low level NW flow will attempt to bring in some low level dry air, especially to the north of where any mesoscale snow band sets up which may result in a sharp cutoff to the north. But there is also some concern that the drier air will limit duration of heavier snow. So the question is can robust synoptic and mesoscale forcing make up for possible decreasing moisture. We think there will be a brief window for a brief period of moderate to heavy snow late tonight to about mid morning, especially across RI and SE MA to Cape Cod. Timing is not great and this would have a significant impact on the morning commute. Snowfall accum forecast is quite challenging for several reasons. First, initial QPF as the rain changes to snow may be wasted on melting, the exact location of a mesoscale snow band is uncertain, and low level drier air may impact snowfall intensity. The previous forecast accums still look reasonable and will not make significant changes. Looking at 2 to 4 inches from near the Mass Pike to the south coast, and 1 to 2 inches to the north. But this will depend on where any banding sets up and this could shift north or south of current forecast. The worst case scenario would be a 4-6 inch snowfall which is a low probability occurrence. No changes to winter weather advisories. While some areas in the advisory may not reach criteria, we felt the impact of snow during the morning commute warrants the advisory. Snow will be exiting the region from west to east during the morning followed by increasing sunshine in the afternoon. Highs will be in the 30s. && .LONG TERM /WEDNESDAY NIGHT THROUGH TUESDAY/... Highlights... * Dry conditions and colder than normal temperatures on Wednesday night and Thursday * Temperatures moderate on Friday as next weather system brings the potential for heavy rain & localized flooding late Friday into Saturday. Flooding risks may be exacerbated by snowmelt. * Leftover rain/snow showers linger into early Sunday. Drying out and seasonably cold on Monday before next system arrives on Tuesday. Details... Wednesday night and Thursday... As the arctic short wave departs, a large 1040mb high pressure will shift east across the Ohio valley into our region. With strong cold air advection and a fresh snowpack, overnight temperatures on Wednesday will fall into the teens in interior MA and CT and low 20s elsewhere away from the coast. The pressure gradient would keep northwest winds blowing at 10 to 15 kts, which would mean wind chills in the single digits in the interior and teens elsewhere. On Thursday, despite mostly sunny skies, most locations will see sub- freezing highs due to continued cold air advection. The albedo effect from the snowpack and low sun angle will also help offset radiational heating. Factoring in the northwest winds at 5 to 10 kts, it will feel like in the 20s area wide during the day on Thursday. By Thursday evening, the center of the high pressure moves offshore into the Canadian Maritimes. Winds become light and variable before switching to the south and southeast after midnight. Clouds will start to increase ahead of the next system. Friday through Saturday night... ***Heavy Rain and Flood Potential*** A potent low pressure system will move north on Friday. A southeasterly flow should see high temperatures moderate to the mid 30s in the interior and mid 40s near the coast. Shower chances increase during the day ahead of the main system. Enough shallow cold air should linger in interior MA and CT for the precipitation to start off as snow or mixed precipitation. Surface maps also have signatures of cold air drainage from the northeast so there may be a few hours of light snow or mixed precipitation. But as warmer air lifts north, any precipitation should change over to plain rain showers by Friday afternoon. By Friday night, the 500mb long wave trough starts digging out of the midwest into the southeast states. This will set up a strong southwest mid level wind flow allowing the deep layer moisture to work into the northeast late Friday into early Saturday morning, with PWATs up to 2-3 standard deviations above normal and pockets of 3-4 standard deviations along the coast. A model blend shows 2 to 2.5 inches of QPF across the area while WPC is less bullish, with 1 to 1.5 inches of QPF for Western MA and 1.5 to 2 inches of QPF elsewhere. Heavy rainfall rates on Saturday morning and afternoon could lead to localized flooding. High temperatures on Saturday look to be in the mid to upper 40s across Western MA/CT and mid 50s elsewhere. An issue of concern is the flooding potential. According to co-op observers` reports this morning, we have about a 6-8 inch snow depth with just under 2 inches snow water equivalent in Northwest MA. That gives us about 30% snow density, which indicates a ripe snowpack. So the combination of snowmelt runoff and heavy rain may result in localized urban and poor drainage flooding. Will continue to monitor river levels for any rises. Sunday through Tuesday... Low pressure will shift northeast into Maine and the Maritimes by Sunday morning, though light rain may linger especially near and N of the Mass Pike. Another cold front may wrap around the departing low late Sunday or Sunday night. May see the rain mix with or change to snow, but looks like the best chance may occur across the east slopes of the Berkshires and possibly the northern Worcester hills during the afternoon before tapering off. Another cold front will sweep across the region by Monday morning, bringing gusty northwest winds and colder air across the region. Expect highs on Monday to be in the 30s and 40s. Another low pressure system looks to impact the area by early Tuesday. With the cold air in place, it should start off as snow before changing to mixed precipitation or rain away from the interior. But since we are still a week away, confidence is extremely low in any specific solution. && .AVIATION /03Z WEDNESDAY THROUGH SUNDAY/... Forecaster Confidence Levels... Low - less than 30 percent. Moderate - 30 to 60 percent. High - greater than 60 percent. Short Term /through Wednesday/... 00Z TAF Update: Tonight and Wednesday...Moderate confidence. Winds shift to the NW tonight behind a strong cold front. Cigs may temporarily lift to VFR in the evening across portions of the interior. Still looking at change from rain to a period of snow 00-06z interior and 06-10z along the coast. MVFR/IFR conditions, with a period of LIFR and brief moderate/heavy snow possible across RI and SE MA late tonight and Wed morning. Conditions quickly improve to VFR with clearing skies from NW to SE late morning into the afternoon. KBOS Terminal...Moderate confidence in TAF. Rain changing to snow around 06z and ending 13-14z. Slushy 1-2 inches possible with an impact to the morning push. KBDL Terminal...Moderate confidence in TAF. Rain changing to snow 04-06z ending 12-13z. 1-2 inches possible with an impact to the morning push. Outlook /Wednesday Night through Sunday/... Wednesday Night through Thursday: VFR. Windy with local gusts up to 30 kt. Thursday Night: VFR. Friday: MVFR/IFR conditions possible. Breezy. Chance SHRA, chance SHSN. Friday Night: Mainly IFR, with areas MVFR possible. Breezy. SHRA. Saturday: Mainly MVFR, with areas IFR possible. Windy with local gusts up to 30 kt. Chance SHRA. Saturday Night: MVFR/IFR conditions possible. Breezy. Slight chance SHRA. Sunday: Mainly VFR, with areas MVFR possible. Windy with local gusts up to 30 kt. Slight chance SHRA. && .MARINE... Short Term /through Wednesday/...High confidence. Tonight... Winds shift to NW tonight with a period of G25 kt, especially over the eastern waters. Hazardous seas persist over outer waters. Vsbys reduced in showers and fog, changing to snow late tonight. Wednesday... Diminishing NW winds and seas but seas remaining AOA 5 ft over the outer waters. Improving vsbys as rain/snow exit. Outlook /Wednesday Night through Sunday/... Wednesday Night: Moderate risk for Small Craft Advisory winds with gusts up to 30 kt. Areas of rough seas. Thursday: Low risk for Small Craft Advisory winds with areas of gusts up to 30 kt. Local rough seas. Thursday Night: Winds less than 25 kt. Friday: Winds less than 25 kt. Areas of seas approaching 5 ft. Chance of rain showers. Local visibility 1 to 3 nm. Friday Night: Moderate risk for Small Craft Advisory winds with gusts up to 25 kt. Areas of rough seas. Rain showers. Saturday: Moderate risk for Small Craft Advisory winds with gusts up to 30 kt. Rough seas up to 12 ft. Chance of rain showers. Saturday Night: Low risk for Small Craft Advisory winds with gusts up to 30 kt. Rough seas up to 12 ft. Chance of rain showers. Local visibility 1 to 3 nm. Sunday: Moderate risk for Small Craft Advisory winds with gusts up to 30 kt. Rough seas up to 12 ft. Slight chance of rain showers. && .BOX WATCHES/WARNINGS/ADVISORIES... CT...Winter Weather Advisory until noon EST Wednesday for CTZ002>004. MA...Winter Weather Advisory until noon EST Wednesday for MAZ012- 013-015>022. RI...Winter Weather Advisory until noon EST Wednesday for RIZ001>007. MARINE...Small Craft Advisory until 7 PM EST Wednesday for ANZ235-237- 250-254>256. && $$ SYNOPSIS...KJC/Chai NEAR TERM...Frank SHORT TERM...KJC LONG TERM...Chai AVIATION...KJC/Loconto/Chai MARINE...KJC/Loconto/Chai
Area Forecast Discussion
National Weather Service Caribou ME
717 PM EST Tue Dec 10 2019 .SYNOPSIS... A cold front crosses the area this evening, with a secondary front crossing Wednesday. High pressure will cross the region Thursday. A warm front will lift north of the region Friday. Low pressure will lift north across Maine Saturday. A cold front will cross the region Sunday. && .NEAR TERM /THROUGH WEDNESDAY/... 715 PM Update: Adjusted the rain coverage given the radar showing steady rainfall from the Bangor and Calais region down to the coast. The latest HRRR and 12Z GEM were handling this area of rain well w/the cold front along the front. This front will be slow to exit the coast as upper flow parallels the sfc boundary. A secondary cold front is moving into northern and western areas bringing some gusty winds and much cold air with it. This boundary is expected to move to the coast overnight aid in pushing the primary front further offshore. Adjustments were made the hrly temps to match then w/the current obs. Rest of the forecast looking ok attm. Previous Discussion... Steady, tight pressure gradient has been in place overhead, with upper and mid level jet passing over this afternoon. Approaching front from Quebec will move towards northern Maine later this afternoon. Impressive mixing w/ low level lapse rates up to 9 c/km and some surface buoyancy will create the chance for gusty winds during its passage this evening and overnight. Winds will increase first across the north this evening, with some slowing of the winds as the front pushes through central Maine and Downeast. Upstream observations show a couple peak gusts to 30kts at higher elevations. Not confident enough winds will be that strong long enough to warrant a Wind Advisory, but have sent a SPS for a heads up. Tacked on to the SPS is also mention of damp surfaces freezing due to rapidly falling temps with the passage. Temperatures around freezing will be through Central Aroostook by late evening, crashing to the teens by daybreak. All of the CWA is expected to be around or below freezing shortly after midnight. Rain showers will be present this evening and early tonight, with a conversion to snow showers and light snow later tonight. The north will only see a few flakes associated with the front, but with moisture lagging further south, Downeast and the immediate coast could see light accums. Moisture lingers just off the coast Wednesday, with coastal Downeast picking up 1-2 inches of snow on the fringe of the precip shield. && .SHORT TERM /WEDNESDAY NIGHT THROUGH FRIDAY/... An upper level trof will cross the region Wednesday night. The trof will support a weak surface low which will track across northern Maine, drawing a strong cold front across the forecast area. Snow showers, possible snow squalls, will accompany the front with the better chances across the north and mountains. High pressure will build across the region Thursday with decreasing clouds north, mostly clear skies Downeast. High pressure begins to exit across the Maritimes Thursday night, with a developing warm front to the west. Clouds will increase across the forecast area Thursday night, with a chance of snow showers across northern areas in the vicinity of the developing warm front. The warm front begins to lift north Friday. Expect mostly cloudy skies across the region Friday. Could also have a slight chance of snow showers across northern areas with the warm front. Temperatures will be at below normal levels Thursday, with near normal level temperatures Friday. && .LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/... The warm front lifts north of the region Friday night, with intensifying low pressure across the Mid-Atlantic region. Expect rising temperatures across the region Friday night with warm advection. Moisture also begins to expand north in advance of the Mid-Atlantic low. Expect increasing rain chances across Downeast areas Friday night, with a wintry mix across northern areas. The intensifying low lifts north from the Mid-Atlantic region across Maine Saturday. The low will draw warmer air northward. Precipitation will remain in the form of rain Downeast, while transitioning to rain across northern areas. The low will then draw a cold front across the region later Saturday night through early Sunday, though the exact timing is still uncertain. Precipitation will transition back to snow or snow showers following the cold front along with much colder temperatures. Snow showers could linger across mostly the north and mountains along with gusty winds later Sunday into Monday. High pressure builds across the region later Monday with partly cloudy/mostly clear skies. High pressure will cross the region early Tuesday. Low pressure is possible later Tuesday, though the track remains uncertain. Precipitation chances/types later Tuesday will depend on the eventual track. Above normal level temperatures are expected Saturday/Sunday. Below normal level temperatures are expected Monday/Tuesday. && .AVIATION /00Z WEDNESDAY THROUGH SUNDAY/... NEAR TERM: VFR at northern terminals with a wind shift this evening and gusty winds. Period of IFR central and Downeast with rain showers and low ceiling tonight. Rain showers transition to snow in the morning through Wednesday. SHORT TERM: Wednesday night...Variable conditions with snow showers and possible snow squalls, particularly across the north and mountains. Thursday...VFR. Thursday night...VFR early. MVFR/IFR conditions developing overnight. A chance of snow showers across northern areas. Friday...VFR/MVFR. A slight chance of snow showers across northern areas. Friday night...Conditions lowering to IFR/LIFR levels with a wintry mix north and rain Downeast. Saturday...IFR/LIFR. A wintry mix transitioning to rain north, with rain Downeast. Sunday...IFR/LIFR early. MVFR/IFR during the afternoon, then VFR/MVFR late. Precipitation transitioning back to snow or snow showers following a cold front. Gusty southwest/west winds following the cold front. && .MARINE... NEAR TERM: Extended SCA to 18z Wed as waves will remain above SCA even though winds fall below Wed AM. SHORT TERM: Small craft advisory conditions early Wednesday night, with gale force wind gusts possible late. Gale force winds gusts possible early Thursday, then small craft advisory conditions late. Conditions falling below small craft advisory levels Thursday night. Conditions below small craft advisory levels early Friday, with small craft advisory conditions possible late. Snow showers possible early Wednesday night. && .CAR WATCHES/WARNINGS/ADVISORIES... ME...None. MARINE...Small Craft Advisory until 1 PM EST Wednesday for ANZ050>052. && $$ Near Term...Cornwell/Hewitt Short Term...Norcross Long Term...Norcross Aviation...Cornwell/Hewitt/Norcross Marine...Cornwell/Hewitt/Norcross
Area Forecast Discussion
National Weather Service Charleston SC
1044 PM EST Tue Dec 10 2019 .SYNOPSIS... A cold front will push through the region tonight, with strong high pressure to build over the area Wednesday through Thursday. A low pressure system will impact the area late week, followed by a return to high pressure over the weekend into early next week. && .NEAR TERM /UNTIL 6 AM WEDNESDAY MORNING/... As of 1035 PM: Coastal observations generally indicate that temperatures have warmed by a degree or two over the past couple of hours. Dewpoints were observed in the mid 60s along the coast. I will update the near term temperatures to align with observations. HRRR sfc condensation pressure deficits fall to less than a mb off the SC coast, representing an area of potential sea fog. If sea fog develops, it will remain until a cold front sweeps from west to east across the region around midnight. I will keep a mention of patchy fog in the forecast. Regional radar indicates very little coverage of showers, I will keep PoPs unchanged. As of 915 PM: Regional radar composite indicated a few patches of light rain lifting north across the forecast area this evening. I will keep PoPs in the SCHC to CHC range. Sfc observations along the coast indicated a few patches of fog, especially along the Charleston County coast. I will keep patchy fog in the forecast until the cold front arrives. Radar data and sfc observations indicate that the cold front was nearing the I-95 corridor from the west, expected to reach the coast by midnight. As of 645 PM: Regional radar images indicated a fine line of showers, associated with a cold front, across the middle Carolinas southwest to the FL Panhandle, tracking east around 15 kts. Until the showers arrive, temperatures should remain nearly steady in the mid 60s. I will update the forecast to refine hourly temperature trends, sky, and weather. Previous Discussion: Tonight: A cold front will advance into the region this evening and should be offshore by the early morning hours. Models have been consistent for several days now showing mainly scattered shower activity along and just behind the front, with the best coverage further north across the southeast South Carolina zones. Don`t expect much measurable rainfall, generally less than a tenth of a inch before shower activity comes to an end late tonight. Immediately ahead of the front, winds will diminish and we could have a narrow window of time where fog could form, mainly along and near the coast. Given that guidance hasn`t handle the fog very well over the past few days, the forecast features just patchy fog. Any fog that does develop will diminish quickly as winds turn offshore and drier low level air moves in. Temperatures will remain quite warm this evening, with most places holding in the mid to upper 60s. Cooler air will filter in late tonight, supporting lows in the low to mid 50s by sunrise Wednesday. && .SHORT TERM /6 AM WEDNESDAY MORNING THROUGH FRIDAY/... Strong high pressure will build over the area from the northwest Wednesday, then shift east toward New England on Thursday. Much cooler air will move into the area with high temps only in the 50s both days. A developing upper trough over the eastern United States late Thursday will bring several upper shortwaves through the area late Thursday through Friday. Meanwhile, an inverted trough will develop off the SC/GA coast, gradually developing into a closed low pressure system before moving up the coast late Friday. Moisture will begin to overspread the cool surface wedge late Thursday afternoon, potentially bringing a few showers to the area. More significant moisture and forcing will affect the area late Thursday night through Friday evening, resulting in widespread showers. Given uncertainty in track of the low, temperature forecast is a bit tricky. Current forecast shows highs ranging from the mid 50s inland to low 60s at the coast. && .LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/... Models are in decent agreement through the long term period. Low pressure and associated rainfall is expected to be exiting the area Friday night into Saturday. High pressure will return in its wake, with dry conditions expected for the latter half of the weekend and early next week. Temperatures will generally be above normal. && .AVIATION /04Z WEDNESDAY THROUGH SUNDAY/... Prior to the 0Z TAFs, regional radar images indicated a fine line of showers, associated with a cold front, across the middle Carolinas southwest to the FL Panhandle, tracking east around 15 kts. Conditions at KCHS and KSAV should remain VFR ahead of the line. The line of showers is timed to reach the terminals late this evening. In the wake of the showers, ceilings should lower to MVFR, close to IFR levels. Based on MOS and forecast soundings, the restrictive ceilings are expected to remain until VFR conditions return during the mid-morning hours on Wednesday. Steady SW winds are forecast ahead of the front, veering from the NW by the pre-dawn hours, then turning from the NE by mid-morning. Extended Aviation Outlook: Flight restrictions are likely Thursday night through Friday night as a low pressure system impacts the area. VFR is expected to return on Saturday. && .MARINE... Tonight: Southerly winds will be in the 10-15 knot range this evening ahead of an approaching cold front. The front should move off the coast in the early morning hours and winds will shift around to northwesterly by sunrise Wednesday. Speeds will be increasing, but should generally be around 15 knots late tonight. Seas will average 3-5 feet. There is still a narrow window of time where sea/marine fog could develop this evening immediately ahead of the front. The forecast mentions patchy fog across the nearshore waters beginning late this evening. Strong high pressure building in from the northwest will result in strengthening north to northeast winds Wednesday through Thursday, along with building seas. Solid Small Craft Advisory conditions are expected everywhere except Charleston Harbor starting at varying times Wednesday. An Advisory is likely for the Charleston Harbor at some point as well, however it appears winds will not reach criteria until Wednesday night, so have held off on issuing for now. The worst conditions across the waters will occur late Wednesday night through Thursday, when gale-force gusts will be possible. Gale Watches and/or Warnings could be needed for at least portions of the waters. Conditions will improve on Friday, although advisories will persist as seas take a bit longer to subside. Low pressure will pass over or near the waters late week into early weekend, followed by a return to high pressure. No additional concerns are expected at this time. && .TIDES/COASTAL FLOODING... Elevated tide cycles are expected late week due to increasing astronomical influences with the full moon on Thursday and strong northeasterly winds. Minor to moderate coastal flooding will be possible with the morning high tides Thursday through Saturday. Coastal Flood Advisories could be required. Also of note, if significant rainfall occurs around the morning high tides Friday and Saturday, the potential for flooding of poor drainage areas could increase along the coast. && .EQUIPMENT... KCLX will remain down until further notice. && .CHS WATCHES/WARNINGS/ADVISORIES... GA...None. SC...None. MARINE...Small Craft Advisory from noon Wednesday to 4 PM EST Friday for AMZ352-354. Small Craft Advisory from 7 AM Wednesday to 4 PM EST Saturday for AMZ374. Small Craft Advisory from 7 AM Wednesday to 4 AM EST Saturday for AMZ350. && $$ NEAR TERM...NED SHORT TERM...JRL LONG TERM...ETM AVIATION...NED MARINE...BSH/JRL TIDES/COASTAL FLOODING... EQUIPMENT...
Area Forecast Discussion
National Weather Service El Paso Tx/Santa Teresa NM
433 PM MST Tue Dec 10 2019 .AVIATION...00Z TAF CYCLE VFR conditions to begin the TAF period. Light and variable winds expected thru the period. Skies increase to SCT-BKN250 after 09Z and the chance of BR and/or FG returns, along with low stratus. From 09Z until 14Z forecaster confidence for BR is stronger at KELP/KLRU/KDMN, however FG could be possible at these sites. Any visibility obstructions will burn off by 15Z. && Hefner .PREV DISCUSSION...151 PM MST Tue Dec 10 2019... .SYNOPSIS... We`ll see more cold temperatures tonight with patchy lowland fog in a few places. Any fog that does form will erode shortly after sunrise tomorrow. The rest of the week will be dry as we begin a warming trend that will peak over the weekend. Increasing winds are expected over the weekend, with windy conditions possible on Sunday. Temperatures cool back down to below normal next Monday as a cold front arrives from the north. && .DISCUSSION... .SHORT TERM...Tuesday Night through Wednesday... Currently satellite shows the area clearing up with a few low level clouds hanging around. These should move out of the area tonight as we clear up. Low temperatures will be around 5 degrees cooler tonight compared with yesterday. Low level moisture hangs around today and tomorrow, keeping our dew points in the mid to high 30s. Mid to upper level dry air calls for efficient radiational cooling tonight. This will set up a good chance for some lowland fog early Wednesday morning (9Z - 14Z). HRRR and NAM are in agreement with at least haze and some patchy fog around the lowlands. GFS is more dry at the surface, but this is typical. Fog and freezing fog are in the grids for the lowlands due to model agreement of surface moisture lingering thru Wednesday, dry mid and upper levels, and very calm winds at the surface. Tomorrow, the fog and/or haze should burn off by 14Z. Thicker cirrus will move into the area tomorrow afternoon, allowing our high temperatures to rise by only 1 or 2 degrees from today. Winds will be calm. No precipitation chances exist for this period. && .LONG TERM... Fairly quiet weather in the extended forecast as dry air shifts into place and the polar jet remains northward closer to the central Rockies. Models seem to have a decent grip on a shortwave through passing through the area Wednesday night. This disturbance looks to be barely noticeable as it has no moisture to work with. PW values will remain below 0.4" with surface dewpoints in the upper 20`s/lower 30`s. Cooler air behind the system won`t have enough juice to reach this far southwest, so we`ll continue the warming trend into Thursday. Thursday through Saturday will feature dry, mostly zonal flow over the region with temperatures peaking 5 to 10 degrees above normal by Saturday. Next weekend shows signs of being breezy to windy as an upper trough approaches from our north and surface pressure gradients tighten in response to lee cyclogenesis. Sunday looks to be the windiest day of the forecast, with current GFS gusts in the 30 to 40 mph range. The only notable precipitation chances exist next Monday across our northern mountain zones as frontal lifting could produce a few rain/snow showers. QPF is light with snow levels at around 6,000 feet, so no snow accumulations over 1" expected at this time. Cooler weather returns next Monday as long term models send cold, dry air southward across New Mexico and west Texas. Lowland highs will return to the 50`s with widespread freezes overnight. && .FIRE WEATHER... Temperatures will dip back down to the freezing mark tonight across southwest New Mexico, with patchy fog possible over the lowlands and mountain valleys. Winds tomorrow will be light from the south, leading to generally Poor ventilation. We`ll see dry weather the rest of the week as temperatures slowly climb to around 8 degrees above normal by the weekend. Winds look to increase again Saturday through next Monday as an upper level system swings by to our north. We could see a few rain/snow showers along our mountain zones on Monday, but most of the area will remain dry. Other than a slim chance Monday, no precipitation chances exist in the current forecast. Cooler air next Tuesday will knock the area back down to below normal. && && .PRELIMINARY POINT TEMPS/POPS... El Paso 36 57 37 58 / 0 0 0 0 Sierra Blanca 32 55 34 56 / 0 0 0 0 Las Cruces 33 55 33 56 / 0 0 0 0 Alamogordo 31 57 32 59 / 0 0 0 0 Cloudcroft 23 42 25 43 / 0 0 0 0 Truth or Consequences 32 54 32 56 / 0 0 0 0 Silver City 31 52 31 55 / 0 0 0 0 Deming 31 55 31 58 / 0 0 0 0 Lordsburg 34 55 32 56 / 0 0 0 0 West El Paso Metro 37 58 38 59 / 0 0 0 0 Dell City 30 58 32 61 / 0 0 0 0 Fort Hancock 34 62 35 61 / 0 0 0 0 Loma Linda 35 54 37 54 / 0 0 0 0 Fabens 35 60 36 59 / 0 0 0 0 Santa Teresa 32 57 32 57 / 0 0 0 0 White Sands HQ 36 57 37 58 / 0 0 0 0 Jornada Range 32 55 32 56 / 0 0 0 0 Hatch 31 57 32 58 / 0 0 0 0 Columbus 34 55 34 57 / 0 0 0 0 Orogrande 32 57 33 57 / 0 0 0 0 Mayhill 28 54 30 56 / 0 0 0 0 Mescalero 25 50 26 51 / 0 0 0 0 Timberon 26 48 26 51 / 0 0 0 0 Winston 27 48 28 54 / 0 0 0 0 Hillsboro 31 55 30 57 / 0 0 0 0 Spaceport 31 55 30 56 / 0 0 0 0 Lake Roberts 26 54 26 56 / 0 0 0 0 Hurley 29 53 30 56 / 0 0 0 0 Cliff 25 59 25 61 / 0 0 0 0 Mule Creek 31 54 30 55 / 0 0 0 0 Faywood 31 53 32 57 / 0 0 0 0 Animas 32 57 32 59 / 0 0 0 0 Hachita 31 55 30 57 / 0 0 0 0 Antelope Wells 32 57 32 60 / 0 0 0 0 Cloverdale 34 54 34 56 / 0 0 0 0 && .EPZ WATCHES/WARNINGS/ADVISORIES... NM...None. TX...None. && $$ 31/30/31
Area Forecast Discussion
National Weather Service Gray ME
1022 PM EST Tue Dec 10 2019 .SYNOPSIS... A cold front will cross the area overnight with colder and drier air moving into the region. A weak storm system will pass well offshore overnight, and while it will spread snow to the northwest of its track it looks to remain too far southeast. Wednesday will see clearing but cold temperatures, with highs barely reaching freezing. An active weather pattern looks to continue this weekend with low pressure moving up the coast delivering another chance of heavy rainfall. && .NEAR TERM /UNTIL 6 AM WEDNESDAY MORNING/... 1020 PM...Just a few minor tweaks to the forecast based on obs overnight. 00Z NAM12 and latest HRRR support the current forecast with some accums to around an inch in SE NH and along the ME coast S of KPWM, otherwise most places will see a coating at best. 655 PM...Tweaked the forecast a bit for the evening and overnight, but overall thinking remains the same with last surge of precip moving thru ahead of the cold front in the south this evening. Still on track for fast moving wave to move along the front to our south and throw some precip back into srn NH and the ME coast. This will be mainly after midnight and p[probably into the morning commute. Did not change amts, and snow will have a tough time accumulating, given the antecedent warm air and the fact that in some spots, especially on the ME coast it will likely fall at temps abv freezing at the start. Still there some hints that some spots in SE NH and along the immediate Me coast, especially could see a burst of heavier snow just before daybreak, so this may give some spots closer to an inch than dusting. Previously...Areas of rain showers continue to move N along the approaching front. This will continue likely to categorical PoP for areas S of the mtns thru the evening. MWN is already cooling off with W flow commences...with 30 degrees and freezing rain reported this hour. Gradually cooling of the column will continue...with some flakes possible as precip winds down this evening. Low level NW flow and drier air will begin to filter into the forecast area tonight. Strong jet aloft and approaching S/WV trof will help to amplify a weak wave along the trailing cold front. This will enhance precip on the cold side of the front. Forecast soundings show a pretty large area of dry air below H7...despite saturation and lift thru the snow growth zone. Given the expected evaporation and below cloud drift of precip...I have cut snow totals back to generally an inch or less across coastal Wrn ME...and far Srn NH. Some of the higher resolution guidance has even less snowfall than that. That being said the mid level frontogenesis will be strong...I just expect a narrow band that remains to our S. && .SHORT TERM /6 AM WEDNESDAY MORNING THROUGH 6 PM WEDNESDAY/... Will continue to see clearing into the afternoon Wed. The main story will be much colder temps than today. Highs will top out around freezing...some 20 degrees cooler than highs this afternoon. A reinforcing cold front will arrive late in the day Wed...with snow showers along the front. Some of these could be squally in nature...but overall it should mainly stay upslope snow shower regime. Some light accumulations are possible before approaching ridge brings an end to upslope. Surface axis arrives Wrn zones may see good radiational cooling. I have edged those valleys down a couple degrees from guidance as a result. && .LONG TERM /WEDNESDAY NIGHT THROUGH TUESDAY/... Cold high pressure crests over the region on Thursday as high temperatures remain in the 20s to teens south to north. Thursday night will be the coldest of the week with many spots dropping to the single digits. Trend since yesterday has been slightly warmer on the low temperatures, but have still persisted on the cold side of the guidance, especially for the mountain valleys as the set up looks favorable for radiational cooling. The next system will move up the east coast Friday night into Saturday morning. Spread on the low location remains quite wide with everywhere from up the St. Lawrence to as far east as the benchmark in play. Ensemble sensitivity shows that much of this variability is due to the placement of the short wave expected to move around the 500mb trough and help to enhance cyclogenesis on Friday. Will likely be another 24 hours or so before we can really start to get some confidence in the surface low track however a warm system, at least aloft, is quite likely and have continued with the rain or snow wording with any frozen precipitation being confined to the north. Too early still for high confidence in rainfall amounts with this system but certain widespread over an inch with two inches possible. With the track of the low up the east coast it allows significant moisture to flow up from the Gulf of Mexico with PWAT reaching up to 2 standard deviations above normal for this time of year. This combination of rain on the now ripening snowpack will lead to good runoff and the potential for flooding will need to be closely monitored. Westerly flow takes hold for the second part of the weekend with some upslope showers and clouds likely continuing into the start of next week. && .AVIATION /03Z WEDNESDAY THROUGH SUNDAY/... Short Term /Through Wednesday/...Most of the area has improved to VFR conditions this afternoon...but precip approaching ahead of advancing cold front will continue localized areas of MVFR or lower in SHRA. Cold front moving into the area will help dry out the low levels...lifting CIGs and bringing an end to SHRA. Will likely see a little bit of upslope cloud cover near MVFR CIGs may linger there into the overnight. Very bearish about -SN have no more than PROB30 for coastal terminals. VFR Wed. Long Term...High pressure will build in through Thursday with widespread VFR holding through Friday. Another low will track up the eastern seaboard bringing widespread rain to the area Friday into Saturday. && .MARINE... Short Term /Through Wednesday/...Winds have dropped below SCA thresholds at this time...but seas remain hazardous outside the bays. With cold front crossing the waters tonight winds are expected to pick back up with gusts 25 to 30 kts thru morning. I have extended the SCA for all but Casco Bay thru that time. There may be another lull Wed before another cold front crosses the waters with an increase in winds and building seas. Long Term...High pressure will build over the waters for Thursday. Another low will move up the eastern seaboard with Gales possible in the Gulf of Maine on Friday night into Saturday. && .HYDROLOGY... Melt from the past few days of rain has lead to modest rises on area rivers, with NOHRSC estimates indicating up to 2 inches of SWE lost across southern NH. This leaves much of the southern portion of NH snow free. Another system with the potential for 1-2 inches of rain will move through Friday night into Saturday. Most of the rainfall for the Saturday will be runoff across the south with southern NH rivers again seeing the potential for flooding. Further north, into the White Mountains snowpack remains in place and even a rain on snow scenario will likely serve to mostly moisten the snowpack with minimal runoff and less chance for flooding. && .GYX WATCHES/WARNINGS/ADVISORIES... ME...None. NH...None. MARINE...Small Craft Advisory until 5 AM EST Wednesday for ANZ150>152- 154. && $$ SYNOPSIS... NEAR TERM...Cempa/Legro SHORT TERM...Legro LONG TERM...Curtis AVIATION...Curtis/Legro MARINE...Curtis/Legro HYDROLOGY...
Area Forecast Discussion
National Weather Service Melbourne FL
924 PM EST Tue Dec 10 2019 ...Areas of Dense Fog Possible Tonight... .UPDATE... Current-Tonight...As of this evening, an area of scattered showers that formed late this afternoon along the west coast sea breeze boundary continues to move along a northeasterly path, bringing periods of moderate to heavy rain to areas from Kissimmee towards Sanford, generally along and south of the I-4 corridor. While thunder is not expected, nor in tonight`s forecast, there may be a fine line with the potential for one or two isolated strikes, although likelihood will decrease as we approach midnight. Minor tweaks were made to the afternoon package, with a rather sloppy pattern leading to a bit of uncertainty overnight. Meso models in disagreement with coverage of fog and precip over the next 12 hours, as the HRRR favors higher rain chances mainly south of Orlando past midnight, with the WRF heavily hitting patchy to dense fog development and little to no shower activity. In a moist pre-frontal airmass, will favor the fog solution, with patchy fog development after midnight, becoming more widespread closer to sunrise. Have added in a chance for showers after midnight with lingering activity expected north of Orlando, with rain chances increasing again after daybreak. No adjustments to temperatures, with lows in the upper 60s tonight. && .AVIATION... Prevailing VFR for most terminals this evening will become MVFR after midnight to IFR towards daybreak as patchy to dense fog develops across much of the area. Most likely vis reductions will be from KDAB to KISM across the interior, with calm to light winds enhancing fog development along with low stratus after 09-10Z. Currently, an area of SHRA from KISM to KSFB will bring brief reductions to interior sites, advancing to the northeast through midnight. By tomorrow, a cold front begins to sink across central FL, continuing at least MVFR cigs through the TAF period. && .MARINE... Tonight...South winds of 15 to 20 knots persist over the northern Gulf Stream waters, building seas up to 6 ft north of Sebastian Inlet. Thus, have added cautionary headlines for small craft operators with the evening update. Conditions will briefly improve tomorrow morning, before decreasing again as a cold front approaches the area. Tonight, generally seas of 3-5 ft and winds near 15 knots. && .PRELIMINARY POINT TEMPS/POPS... DAB 83 66 73 63 / 20 40 30 40 MCO 86 68 78 63 / 20 40 40 20 MLB 84 68 78 69 / 20 40 50 40 VRB 84 68 80 70 / 20 40 50 50 LEE 85 66 76 59 / 20 30 30 20 SFB 85 68 76 62 / 20 40 30 30 ORL 86 68 77 63 / 20 40 30 20 FPR 84 67 81 71 / 20 40 50 50 && .MLB WATCHES/WARNINGS/ADVISORIES... FL...None. AM...Small Craft Advisory from 4 PM Wednesday to 4 AM EST Friday for Flagler Beach to Volusia-Brevard County Line 0-20 nm- Flagler Beach to Volusia-Brevard County Line 20-60 nm- Volusia-Brevard County Line to Sebastian Inlet 0-20 nm- Volusia-Brevard County Line to Sebastian Inlet 20-60 nm. Small Craft Advisory from 1 AM Thursday to 4 AM EST Friday for Sebastian Inlet to Jupiter Inlet 0-20 nm-Sebastian Inlet to Jupiter Inlet 20-60 nm. && $$ Smith/Weitlich/Leahy
Area Forecast Discussion
National Weather Service Marquette MI
1001 PM EST Tue Dec 10 2019 .UPDATE... Issued at 1000 PM EST TUE DEC 10 2019 Water vapor imagery and RAP analysis show a shortwave approaching Lake Superior. Ahead of this feature, low-level winds have been backing across Upper MI with land breeze aiding the backing winds out over southern Lake Superior. Thus, there has been a notable ne lifting of a dominant LES band over eastern Lake Superior which is tied to the backing wind. LES has also been lifting n across western Upper MI. Forcing from shortwave is now beginning to overspread western Lake Superior, and based on deep layer q-vectors, this forcing should give a healthy boost to ongoing LES. Webcams in Keweenaw County have showed a notable increase in snow recently, and expect this to continue. This heavier snow is likely tied to and is likely an extension of the convergence band that originates along the nw shore of the Bayfield Peninsula. As the shortwave moves across the area overnight, low-level winds will veer nw, shifting the dominant band s. The convergence will become less focused as this occurs since the focused convergence at the orgination point near the Bayfield Peninsula falls apart. Nonetheless, still expect a band of hvy snow to drop s across nw Upper MI late tonight along the wind shift, potentially reaching KIWD for a brief time Wed morning. Will probably be roughly 14z before the wind shift/dominant LES band reaches Alger/Luce counties, providing a brief period of hvy snow followed by more traditional wnw/ese oriented wind parallel bands. With the heavier LES hanging out across the Keweenaw for several more hrs, wouldn`t be too surprised if a few high terrain locations flirt with warning criteria snowfall. Elsewhere, wind chills are the main concern, and headlines will remain unchanged. As often occurs, this will be another situation where wind chills will not solidly fall into the advy range of -25 to -34 across the advy counties. Those interior locations that are more open and thus have a little more wind will likely reach advy (KIWD obs site is a good example) while sheltered areas with less wind will fall short of -25F. && .SHORT TERM...(This evening through Wednesday) Issued at 350 PM EST TUE DEC 10 2019 Water vapor satellite this afternoon shows a deep upper level trough over the north-central U.S. MSAS analysis shows 1030 mb high pressure over the mid Missouri Valley, on the back side of the trough. Subtle surface troughing persists over Lake Superior today as well. As a secondary mid-level short wave embedded in the aforementioned long wave troughing, this surface trough is expected to tighten up. The enhanced convergence along this surface trough will also become the focus for heavier and more persistent lake- effect snow this evening over the Keweenaw, which will be one of the two main stories this forecast period. (The other will be the cold; more on that later.) The main limiting factor will be that this band looks transient. Most models show the strong convergence signal developing late this afternoon over the higher terrain south of Houghton, then shifting north across the Keweenaw overnight before coming back south by Wednesday morning. This should help spread the wealth in snow amounts rather than confining greater amounts to a smaller area. The other limiting factor will be the snow ratios. With such cold air moving in, model forecast soundings confine all of the snow growth to the lowest 2 kft or so. So there will be some dendritic growth, but just as much or more snow growth as lower-ratio plates and columns. Therefore, went with SLRs generally between 15:1 and 18:1, which with the forecast QPF gives about 4-7" overnight from just NE of Ontonagon up through Copper Harbor and about 10 miles either side of this line. Still, very high lake-based instability with sfc-850 mb delta T`s of 25 C or more and strong convergence along the trough will lead to periods of intense snowfall rates and could allow for these amounts to overperform somewhat. Another 1-2" of lighter, more typical NW flow multi-band LES is expected over the Keweenaw tomorrow. Although the main show will be in the overnight hours, opted to extend the Winter Weather Advisory until 15z for the west to cover any lingering impacts into the morning commute, including the low wind chills. meanwhile, this convergence band will be sinking south across Lake Superior tomorrow, leading to a shoreline LES band from about Melstrand east to Whitefish Point where 2-5" of new snow is expected tomorrow (in addition to about an inch overnight tonight). Given that this snow would just barely hit advisory criteria, but the above amounts are confined to a narrow area right along the shore, will not issue any new Winter Weather Advisories for the east and instead let those expire tonight at 03z as scheduled. Now onto the cold... with clearing skies away from the aforementioned lake-effect areas this evening and fresh snow cover, there should be strong radiational cooling tonight. However there will also be enough gradient wind to keep the PBL from fully decoupling. This is both a blessing and a curse; it`ll keep actually temps up a few degrees (though still very cold) but lead to very cold wind chills. Wind chills tomorrow morning will be about -15 to - 25 along the lakeshores, and as cold as -35 over the interior. Given that the overwhelming majority of areas will not hit -35, will keep the Wind Chill Advisory as is rather than upgrading to warning. With highs mostly in the single digits tomorrow (teens along the immediate lakeshores) and winds staying in the 10-15 mph range, wind chills will only improve to about -5 to -10 in the afternoon. .LONG TERM...(Wednesday night through Tuesday) Issued at 253 PM EST TUE DEC 10 2019 Forecasted upper level pattern hasn`t changed much, with a deep long wave trough extending south from Huron Bay with a ridge in place over the west coast. The ridge will shift east, creating a quasi- zonal flow over the region with a shortwave embedded moving through Thursday. This is followed by long wave troughing again this weekend before it shifts east as deeper troughing extends across the central US by early next week. This pattern will keep cold arctic air in the forecast overnight Wednesday but as the flow becomes more zonal, the lake effect will turn off and temperatures will increase going into the weekend ahead. The shortwave passing through Thursday followed by the weekend`s storm, will keep snow in the forecast at least through the weekend. Overnight Wednesday, with brief ridging building in across the region followed by increasing warm air advection, the lake effect regime for the W and NW snow belts will come to end sometime close to midnight. As the ridge builds in, it`ll give us another cold night. Overnight lows -5 to -10F will be possible in the interior west/central and near 0F elsewhere. Wind chill -20 to -10F will be possible for the coldest interior areas. Thursday, isentropic lift and warm air advection ahead of shortwave will help create some widespread snow across the region. Right now the better forcing looks in place over northern Lake Michigan into the eastern UP so snow totals will likely be higher close to 5-6 inches during the day there. Elsewhere expect at least 2-3 inches CWA-wide during the day Thursday. With the return flow and warm air advection, high temps look to rebound into the mid-teens in the interior west/central and climb into the low to mid 20s elsewhere. Friday looks largely drier, with most moisture associated with Thursday`s shortwave exiting by the morning hours. There are some inconsistencies in lingering moisture and a system to the north, so at the moment keeping slight chances for POPs. Better moisture with some isentropic enhancement arrives Saturday so widespread snow is likely. Some models, namely the GFS, appear to be outliers, suggesting upwards of 0.25-0.5" of QPF over the central UP so certainly something to keep an eye on. Sunday after this system exits, some lake effect NW snow showers look possible until high pressure over the northern Plains settles in overnight Sunday into Monday. && .AVIATION...(For the 00Z TAFS through 00Z Wednesday evening) Issued at 704 PM EST TUE DEC 10 2019 With a w to nw flow of arctic air across Lake Superior, KCMX will be impacted by lake effect snow showers thru the period. Backing winds this evening, followed by veering winds late tonight will likely result in a hvy snow band periodically moving across the terminal. Typical for lake effect, conditions will be quite variable at times, but in general, expect conditions to vary mostly btwn IFR and LIFR into Wed morning. Heaviest snow showers will result in conditions falling blo airfield landing mins. Conditions may improve to prevailing MVFR Wed aftn as subsidence and drying should lead to some weakening of shsn. At KIWD, VFR conditions will likely prevail into the overnight before veering winds late tonight bring lake effect shsn back to the terminal. Expect conditions to fall to prevailing IFR Wed morning before improvement to MVFR then VFR by late Wed aftn as winds back, shifting shsn northward. At KSAW, w to nw winds will not be favorable of lake effect shsn. While VFR conditions are expected to prevail thru the fcst period, not out of the question that there could be a few periods of MVFR cigs and flurries. && .MARINE...(For the 4 PM Lake Superior forecast issuance) Issued at 415 PM EST TUE DEC 10 2019 Arctic air spilling in across the region will bring northwest to west winds between 20-30 kts with gale force gusts at bridge level to 35kts possible tonight. Winds will begin weakening tomorrow in the east but gale force gusts to 40kts will continue for the eastern lake. With this cold air spilling in and the winds, heavy ice accumulation due to freezing spray will be possible across the entire lake tonight into Wednesday. Additionally, some lake effect snow showers could temporarily reduce visibilities tonight into tomorrow. Winds will shift to southwest to south ahead of and during the next shortwave moving through Thursday. These southern winds will be light and help to warm things up to end the freezing spray concerns. These nicer conditions will linger into the early part of the weekend. Another system will move through the region Saturday and winds will swing around to the north Saturday afternoon into the evening. The colder air will help produce some gale force gusts at bridge height, mainly over the central lake and areas where freezing spray will be possible. && .MQT WATCHES/WARNINGS/ADVISORIES... Upper Michigan... Wind Chill Advisory until noon EST /11 AM CST/ Wednesday for MIZ004-005-009>013-084. Wind Chill Advisory until 10 AM EST Wednesday for MIZ006-007-014- 085. Winter Weather Advisory until 10 AM EST Wednesday for MIZ001>003. Lake Superior... Heavy Freezing Spray Warning until 7 PM EST /6 PM CST/ Wednesday for LSZ162-240>244-263>267. Gale Warning until 5 PM EST Wednesday for LSZ264>267. Lake Michigan... None. && $$ UPDATE...Rolfson SHORT TERM...RJC LONG TERM...JP AVIATION...Rolfson MARINE...JP
Area Forecast Discussion
National Weather Service Spokane WA
647 PM PST Tue Dec 10 2019 .SYNOPSIS... Bands of light snow will spread across central and eastern Washington this evening and overnight and linger over the Idaho Panhandle Wednesday morning. Motorists should expect slick conditions during the morning commute Wednesday. Another storm system will bring heavy mountain snow to the region late Wednesday night into Friday. && .DISCUSSION... Evening update: the newest models are coming in for tonight`s and Wednesday weather. There is not much difference from the previous runs. I did adjust QPF/Snow amounts slightly, which added maybe a quarter to half inch of snow in spots. Yet the overall 1/2 inch to 2 inches remain the average amount in the forecast. Snow has been reported around Omak and brief snow showers were seen on the Wenatchee Airport webcam. The HRRR models and other hi-resolution CAM models indicate the main snow threat remains near the Cascades and central WA this evening, then starts to move into the Spokane area and Palouse and northern mountains between 10 pm and 2 am and continues to about sunrise, give or take an hour. I added some freezing rain potential over the deeper Columbia Basin and into the Palouse/L-C valley, though it could also be general rain mixed with snow. Overall the threat of freezing rain is slight, but the risk exists. I also increased fog coverage, with areas such as Pullman and Ephrata reporting decent fog in and around. /Cote` && .AVIATION... 00Z TAFS: Light snow will spread east of the Cascades between 00-02z and reach Spokane, Coeur d`Alene, and Pullman between 06z- 09z. Most airports across the Inland Northwest will receive measurable snow. Short range ensembles forecast a half inch to as high as 2 inches by sunrise Wednesday. Some freezing rain may mix in near EAT/MWH/PUW and on the tail end of the precipitation around GEG. Some general rain may also mix in around SFF/PUW/LWS. Snow chances wane in the morning, but without a strong push of drier air expected low clouds and fog. Some improvement is possible toward the mid to later afternoon with additional shower chances developing. /Cote` && .PRELIMINARY POINT TEMPS/POPS... Spokane 29 37 34 43 32 40 / 90 40 90 60 40 10 Coeur d`Alene 29 38 34 42 34 38 / 90 60 100 70 60 20 Pullman 29 40 36 46 35 41 / 90 60 90 70 50 30 Lewiston 34 45 39 50 39 46 / 70 50 80 70 50 30 Colville 26 38 30 42 29 40 / 80 20 90 40 30 10 Sandpoint 28 36 34 40 34 37 / 70 50 100 90 70 30 Kellogg 32 37 36 40 35 38 / 90 70 100 100 90 60 Moses Lake 29 39 31 45 30 45 / 80 30 90 30 20 10 Wenatchee 30 37 31 42 31 42 / 60 30 80 50 30 10 Omak 27 36 31 40 29 38 / 50 10 90 40 20 10 && .OTX WATCHES/WARNINGS/ADVISORIES... ID...Winter Storm Watch from Wednesday evening through Friday morning above 3000 feet for Central Panhandle Mountains-Northern Panhandle. WA...Winter Storm Watch from Wednesday afternoon through Friday morning for the cascade crest including highway 2 between coles corner and stevens pass for East Slopes Northern Cascades. && $$
Area Forecast Discussion
National Weather Service Phoenix AZ
431 PM MST Tue Dec 10 2019 .UPDATE...Updated aviation discussion. && .SYNOPSIS... Drying conditions under weak high pressure will bring mostly sunny skies today with highs in the mid to upper 60s. A weak weather system mostly skirting by to the north of Arizona will then bring mostly cloudy skies tonight into early Wednesday. Increasing high pressure and warming conditions are then seen for late week with high temperatures likely topping 70 degrees over the lower deserts for Friday and Saturday. Another weak but dry weather system should bring cooler temperatures into early next week. && .DISCUSSION... High pressure will dominate the weather pattern through next week, with a couple of weak disturbances moving across the region. The first wave will move through late tonight through tomorrow and result in an increase in high clouds. Current, satellite imagery already shows thicker high clouds moving into southeast California, with these clouds expected to spread eastward into southwest and south-central Arizona by later this afternoon. Due to increased cloud cover overnight, we nudged overnight lows a couple of degrees warmer. In addition, the enhanced cloud cover and warmer temperatures will bring down the threat for dense fog re-development tomorrow morning, but latest HRRR guidance continues to indicate patchy fog developing, especially in northwest Pinal county and around the San Carlos area in southern Gila county. It looks like the best window for fog will be from around 4 am to 10 am MST Wednesday morning. High clouds will clear from west to east tomorrow, with mostly clear skies expected in southeast California by mid-morning and in southwest and south-central Arizona by early-afternoon. Strong high pressure will then begin to build into the region in the wake of the aforementioned wave and remain situated over us through the early part of the weekend. This will lead to a warming trend with highs in the upper 60s/low 70s by Friday and Saturday. it still looks like another weak weather system will move across the region on Sunday and bring rain to the far eastern portions of southern Gila county. Most of our forecast area will likely not see any rain from this system, however, what we will see is another cool down with high temperatures across the lower deserts dropping back into the low 60s by next Monday. && .AVIATION...Updated at 1755Z. South-Central Arizona including KPHX, KIWA, KSDL, and KDVT: High clouds will increase this evening into tomorrow as a weak upper disturbance moves through the Southwest. Bases should remain AOA 25 kft while coverage is SCT-BKN. Otherwise, very light winds with general diurnal tendencies will persist through the next 24 hours with periods of variability. Southeast California/Southwest Arizona including KIPL and KBLH: SCT-BKN high clouds will persist through Wednesday morning with bases AOA 25 kft. Winds will remain light and variable through the TAF period, favoring typical diurnal tendencies. && .FIRE WEATHER... Thursday through Monday: Dry conditions under increasing high pressure aloft will prevail through Saturday before a weak low pressure system affects the region Sunday into Monday. Moisture levels with the late weekend system should be too dry, hindering precipitation chances. Minimum humidity levels initially should stick around 25-30% much of the period, potentially lowering slightly into early next week. Winds will stay light through Saturday before some breezy conditions move in for Sunday and Monday. && .SPOTTER INFORMATION STATEMENT... Spotters should follow standard reporting procedures. && .PSR WATCHES/WARNINGS/ADVISORIES... AZ...None. CA...None. && $$ DISCUSSION...Hernandez AVIATION...Rogers/Benedict FIRE WEATHER...Kuhlman
Area Forecast Discussion
National Weather Service Blacksburg VA
637 PM EST Tue Dec 10 2019 .SYNOPSIS... A cold front advances to the coast tonight. A wave of low pressure is expected to develop along the front tonight before moving off the Mid- Atlantic coast Wednesday. Another storm system will impact the region for the end of the week. && .NEAR TERM /THROUGH WEDNESDAY/... As of 620 PM EST Tuesday... Adjusted temps down in the west as colder air starting infiltrate faster and snow making it as far east as the WV/VA border, but no accumulations yet. Radar coverage overall is patchy/spotty/bandy in nature, and the latest HRRR and RAP showing this a bit better than the 18z Nested NAM. Very little accumulation will occur early given wet/milder ground, but as temperatures sink through the 20s overnight we expect accumulations on grassy and roads to occur. The low levels per forecast soundings depict limited threat of freezing rain in the mountains of WV and far SW VA so dropped that out. Mainly a rain to snow scenario possibly some light sleet/freezing rain along the Blue Ridge. Do not foresee any changes to snow amounts or headlines as latest models depict better accumulations in the higher elevations of far SW VA with less to the east, but this is contingent on how any stronger banding if any occurs with secondary wave of low pressure forming along the front. Previous discussion from earlier this afternoon... Posted a winter weather advisory for this evening into Wednesday morning for a wintery mixture of snow, sleet and freezing rain. Cold air will transition moisture (rain) along and behind the cold front this evening into Wednesday morning into a wintry mixture of snow, sleet and freezing. Snow accumulations of one to three inches are possible especially in the higher elevations. A light glaze of ice is possible especially along the southern Blue Ridge mountains. The best chance of the ice will be on elevated surfaces. Low temperatures tonight will be in the upper teens in the northwest mountains in Greenbrier county to the mid 30s in the piedmont. Lingering precipitation behind frontal boundary Wednesday will rapidly taper off from west to east Wednesday morning with some wet flakes making it a bit east of the Blue Ridge as precipitation ends. A large area of high pressure will build east from the Tennessee valley Wednesday. High temperatures Wednesday will be the mid 20s in the northern mountains to the upper 40s in the piedmont. && .SHORT TERM /WEDNESDAY NIGHT THROUGH FRIDAY NIGHT/... As of 230 PM EST Tuesday... Surface high pressure builds in from the Tennessee Valley then Ohio Valley on Wednesday night then the high is centered over the Mid Atlantic region on Thursday. This high will remained wedged down the east slopes of the central Appalachians through at least Friday morning. Models still showing differences on the location of the development and track of a coast surface low on Friday and Friday night. The ECMWF is the slowest of farthest inland while the Canadian moves the northeast faster. The GFS is between these two for the track but has a deeper low. Expecting warm to neutral advection Wednesday night and Thursday. Warm nose temperatures by the end of the day Friday are well warm enough to support complete melting and therefore just rain or freezing rain. Will be keeping hourly temperatures on a non-diurnal trend and on the cool side of guidance for Friday. Since surface dew points will be in the lower 20s to lower 30s, temperatures may even drop at the onset of precipitation. && .LONG TERM /SATURDAY THROUGH TUESDAY/... As of 230 PM EST Tuesday... Long wave trough will be crossing the eastern United States Saturday and Sunday. Monday the Mid Atlantic region will be in broad southwest 500MB flow between ridging the western Atlantic and troughing over the central United States. This through arrives in the East on Tuesday. The coastal low will be far enough north that wedge will be gone and precipitation will be ending Saturday with mainly northwest flow and upslope clouds and rain/snow showers on the western slopes of the central Appalachians. Another cold front moves through the region on Saturday night. Air mass that comes in behind the front is colder. High pressure follows for Sunday. Monday a low develops on the front in the Southern Plains which reaches the Mid Atlantic and Southeast United States on Monday and Tuesday. Strong jet diffluence Monday and Tuesday will result in prolonged widespread precipitation. && .AVIATION /00Z WEDNESDAY THROUGH SUNDAY/... As of 628 PM EST Tuesday... Aviation conditions improve at times east of the mountains this evening but should see vsbys/cigs start to drop to MVFR or lower overnight. Expect the lower cigs/vsbys in the mountains with rain changing to snow before ending by 12z Wed. Snow is going to make it into LYH as well, but should be short-lived. Expect some vsby/cigs to be LIFR. Wind speeds will be increasing a little behind the front this evening with some gusts to 20kts at BCB/ROA. Conditions improve Wednesday morning into Wednesday afternoon to VFR. Forecast confidence is medium. .Extended Aviation Discussion... Anticipate VFR into Thursday, followed by poor flying conditions again for Friday and into the weekend as low pressure envelops the southeast CONUS. There is also the potential for this system to produce freezing rain across parts of the Mid- Atlantic Friday. Sub-VFR is possible on Saturday with precipitation and clouds. Some rain showers may linger in the northwest Sunday. Forecast confidence is moderate to high. && .RNK WATCHES/WARNINGS/ADVISORIES... VA...Winter Weather Advisory until 7 AM EST Wednesday for VAZ007- 009>020-024. NC...Winter Weather Advisory until 7 AM EST Wednesday for NCZ001- 002-018. WV...None. && $$ SYNOPSIS...KK/RR NEAR TERM...KK/WP SHORT TERM...AMS LONG TERM...AMS AVIATION...KK/RR/WP