Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 12/03/18

Area Forecast Discussion
National Weather Service Cleveland OH
1023 PM EST Sun Dec 2 2018 .SYNOPSIS... Low pressure centered over the middle Mississippi River will follow closely behind the front and move through the central Great Lakes tonight and into Canada for Monday. The associated cold front will move through the area on Monday. High pressure attempts to slowly build in from the west for mid-week. Another cold front will move across the region on Thursday. && .NEAR TERM /THROUGH MONDAY/... Cold front has shifted east of the area and both the threat of thunderstorms and severe weather has ended. A band of showers is moving across NE Ohio and NW Pennsylvania ahead of the upper level wave. These will move east out of the area after midnight, leaving just a low chance of showers as the wrap around moisture and low level trough slide east. Temperatures are falling quickly behind the front, already in the lower 40s across most of NW Ohio. Previous discussion... It is a fantastic mild and breezy Sunday afternoon. But there is usually a price to pay for this nice weather for this time of year. Hi-res guidance and forecast models suggest a little bit of active weather late this afternoon into early this evening. There are no changes to the previous mesoscale discussion written earlier today. We are watching closely the area from a line near Elyria south to Wooster eastward across northeast Ohio into northwest Pennsylvania between 4 pm and 9 pm. Convection will start to develop across northwestern Ohio between 3 and 4 pm. These storms will move quickly eastward at nearly 40 to 50 mph and a few of them will become severe by the time they reach the I-71 corridor. Damaging winds up to 65 mph will be the main threat followed by small hail up to nickel size. Given the very high shear in the low levels of the boundary layer, we can`t rule out an isolated tornado threat. Usually, when we have high shear but low instability this time of year...we see low top supercells and mini bow like structures. We expect most if not all the storms to be weakening and east of our NW Pennsylvania counties by 9 pm this evening. Scattered light showers will be around tonight and temperatures will begin to fall as winds become more westerly. A secondary cold front will move through Monday morning and change our winds more northerly by midday and afternoon. Temperatures will continue to fall slowly during the day. We will see rain showers change to snow showers during the afternoon. Snow showers could be moderate at times especially in the primary and secondary Snowbelt region down wind of the lake and higher elevations. It will take a while before snow will be able to accumulate because of the warm ground and temperatures around freezing. Lake effect snow showers will continue across northeast Ohio and northwest Pennsylvania Monday night. We will likely see some light accumulations after sunset and as temperatures fall into the upper 20s. 1 to 2 inches will be possible in primary and secondary Snowbelts. Isolated higher amounts could be possible in primary Snowbelt areas. Previous mesoscale discussion... We have been looking at the newest Hi-Res model data this morning for the storm threat late this afternoon and evening. We are seeing the potential for MUCape to develop between 400 and 700 J/KG thanks to all the extra sunshine and temperatures expected to reach the low to mid 60s this afternoon. One note to point out is that forecast low level CAPE 0-1km is around 100 to 200 J/KG which is concerning. 0-1km helicity values are running about 200 to 500. 0-6km Bulk shear magnitudes are in the 50 to 70 knots. Surface winds just along the surging front will be about 170 to 190 degrees. With these given parameters, we do expect a few low topped supercell like storms right along the front across northern Ohio into NW Pennsylvania. We really like the the way the HRRR and 4km NAM has for timing of development and evolution of this potential severe weather event. There will be a damaging winds and isolated tornado threat. We will see CU and convection development just east of Toledo down to Lima, Ohio between 3 pm and 4 pm. Strong to severe convection from near Lorain County to Mansfield area by 5 pm. The Cleveland area down the I-71 corridor between 5 and 6 pm. NE Ohio to Akron/Canton area between 7 and 8 pm and NW Pennsylvania between 8 pm and 9 pm. That is our best expectations at this time. && .SHORT TERM /MONDAY NIGHT THROUGH WEDNESDAY NIGHT/... Light lake effect will set up Tuesday but no deep moisture source. Better chance on Wednesday as the synoptic moisture increases ahead of the next front. High finally moves off the SE Coast, which will all next cold front to push through on Thursday. Looks like a widespread synoptic event, but system will push through so quickly do not expect much in the way of accumulations. && .LONG TERM /THURSDAY THROUGH SUNDAY/... Below normal temperatures continue through the long term forecast. ECMWF coming into agreement with GFS for next weekend. YDY the ECMWF had low tracking across the Ohio Valley Saturday into Sunday. Today both models have high pressure over the forecast area through the entire weekend, with the low tracking much further south. So next weekend should be cool, but dry with some sun. && .AVIATION /00Z Monday THROUGH Friday/... Showers with isolated thunderstorms accompanying a cold front will move across NE Ohio/NW PA producing pockets of strong winds in excess of 40 knots. These winds may impact YNG/ERI over the next hour or two with the potential for stronger winds decreasing beyond that time. Ceilings will lower behind the front with most sites settling into the MVFR range overnight. Southwest winds will be remain breezy overnight with gusts of 20-25 knots and a few scattered showers overnight. Otherwise winds will shift to the northwest with the passage of a secondary front during the day on Monday. Scattered showers will mix with snow during the afternoon and eventually transition to all snow by early Monday evening. Have included MVFR visibilities with the mixed precip and snow but can not rule out periods of IFR. OUTLOOK...Non-VFR probable on Monday into Tuesday with snow as a cold front crosses the region. && .MARINE... Currently Low near the Thumb of MI with strong cold front extending SW to S of Kansas City. Models in good agreement tracking the Low into New England Monday, with the trailing cold front pushing across the Lake Monday morning. Surface winds will turn to the southwest and increase to 15 to 25 knots tonight as a prefrontal trough swings across the Lake, and 925 winds of 35 knots. Winds turn to the NW behind the front and gradually diminish. Expect Small Craft Advisory to last until Monday evening. After that high pressure tracks across the Ohio Valley Wednesday, then moves off the SE coast Thursday. That will allow another cold front to push across the Lake on Thursday. && .CLE WATCHES/WARNINGS/ADVISORIES... OH...None. PA...None. MARINE...Small Craft Advisory until 10 PM EST Monday for LEZ145>149. Small Craft Advisory until 10 AM EST Monday for LEZ144. && $$ SYNOPSIS...Griffin NEAR TERM...KEC/Griffin SHORT TERM...DJB LONG TERM...DJB AVIATION...KEC MARINE...DJB
Area Forecast Discussion
National Weather Service Grand Junction CO
705 PM MST Sun Dec 2 2018 .UPDATE... Issued at 701 PM MST Sun Dec 2 2018 Persistent light snow continues over the central valleys of the western slope. Reports of a few accidents on bridges and overpasses has prompted the issuance of a Special Weather Statement, covering the threats of refreezing surfaces and 1-3 inches of snow from now through midnight tonight. The statement focuses on areas from Grand Junction eastward to Glenwood Springs, however the higher terrain along Douglass pass, Rio Blanco Hill, and the Grand Mesa will also be impacted. Satellite and radar trends noted in the previous AFD update continue. UPDATE Issued at 559 PM MST Sun Dec 2 2018 Radar and satellite trends as well as surface observations and webcams indicate that snow is winding down over eastern Utah and western Colorado this evening. Therefore, the Winter Weather Advisory will be allowed to expire at 6pm. Interestingly, light snow has persisted over the central valleys, especially over Grand Junction and northward to Rifle along I-70. What is left of the 700mb low pressure center currently sits over far southern Mesa County, and some cooler cloud tops have blossomed to the east of the low. These colder cloud tops are co- located with an area of increasing radar returns. 0z radiosonde data from GJT shows a particularly saturated portion of the profile between 600 and 750mb, where temperatures are running between -14 and -8C. Current thinking is that a slight amount of lift on the east side of the decaying low, combined with temperatures on the lower end of the dendritic growth zone, are combining to maximize crystal production and snow rates over Mesa and Garfield County. High res guidance has not picked up on these trends very well, so we will have to carefully monitor radar and satellite for Short Term forecast updates this evening. The expectation is that this activity will diminish in about 2-3 hours as the low pressure falls apart. We`ll see... && .SHORT TERM...(Tonight through Monday night) Issued at 139 PM MST Sun Dec 2 2018 An energetic trough with support from a 140 kt jet rounding its base and divergent flow aloft leading the way will continue to lift slowly NE over western CO and eastern UT. Temperatures are cold enough for snow to reach and accumulate in the lower valleys through about 6 PM this evening. A Winter Weather Advisory continues until that time for most of southwest CO. Both the HRRR and HiRes models show support for precipitation decreasing this evening and continuing to move thru central and northern CO and UT. At sunrise Monday what`s left will be over the northwest CO plateau and central CO mountains and valleys. Believe low stratus and maybe some fog will hang in the central valleys through the morning. Remnant orographic showers in the northern and central mountains will slowly dissipate Monday night. .LONG TERM...(Tuesday through Sunday) Issued at 139 PM MST Sun Dec 2 2018 The long range will be characterized by progressive large amplitude systems. Strong high pressure will move through the Great Basin and Central Rockies Tue. through Wed., being built up by a deep low pressure system developing off the southern CA coast. The remnants of a weak warm front will produce a very slight chance of showers Tuesday night and Wednesday morning. On Thursday the low will begin moving onshore and it will influence weather across all of the southwestern U.S., southern Great Basin and Central Rockies. Plenty of moisture is expected to be carried into the area from the SW. This system should focus on southeast UT, southwest CO and the CO central and southwest mountains until the trough passes overhead Friday night. If this solution holds together, the mountains and foothills of southwest CO should bare the brunt of the storm. Strong high pressure will begin moving in Friday night and Saturday morning. On Sunday a large ridge will build over the western U.S. ahead of another deep low developing off the west. && .AVIATION...(For the 00Z TAFS through 00Z Monday evening) Issued at 508 PM MST Sun Dec 2 2018 Low clouds and snow continue across much of the forecast area. For the overnight hours, conditions will start improving for KDRO and eventually KCNY. Other TAF sites will likely vary from VFR to IFR under showers as they move through. Another concern will be fog where the snow has ended. Cloud cover may inhibit formation so will amend TAFs as needed. By 12Z, conditions will be worst along the I-70 corridor so KRIL, KASE, and KEGE will likely see MVFR/IFR conditions until 18Z, give or take. Southern areas will see FEW to SCT skies while the rest of the area will continue to see BKN ceilings. && .GJT WATCHES/WARNINGS/ADVISORIES... CO...None. UT...None. && $$ UPDATE...MAC SHORT TERM...CC LONG TERM...CC AVIATION...TGR
Area Forecast Discussion
National Weather Service Lincoln IL
931 PM CST Sun Dec 2 2018 .UPDATE... Issued at 920 PM CST Sun Dec 2 2018 Spotty rain showers will transition to snow showers from NW to SE overnight. There appears to be a narrow corridor of enhanced forcing for precipitation across our SW counties, especially after snowfall begins. This looks to be a high PoP and low QPF situation. Still, a dusting of light snow could occur across that area through mid-morning, possibly creating some slippery spots for the Monday morning commute. Gusty northwest winds could create some reduced visibilities during snow showers. Clouds will help keep low temps from dropping off too far from the mid-evening readings, with around 30 toward Galesburg and the mid to upper 30s S of I-70. The shortwave will depart to the east Monday afternoon, taking precip with it. However, advancing cold air will limit high temperatures to climbing only a few degrees above morning lows. Most areas will remain in the 30s for highs. Update this evening was to mainly bump up the PoPs/snow wording slightly overnight into Monday. The latest forecast info is already available. && .SHORT TERM...(This evening through Monday) ISSUED AT 230 PM CST Sun Dec 2 2018 20z/2pm surface analysis shows a 994mb low centered over eastern Michigan, with a trough axis extending W/SW across north-central Illinois into northern Missouri. Widespread showers have developed along the trough, particularly across the northern half of the KILX CWA in advance of a well-defined upper low. As the upper feature gradually passes to the east, colder thermal profiles on its back side will allow the rain to transition to snow from west to east across the area tonight. Minor snow accumulations of a couple tenths of an inch are expected, mainly on grassy surfaces as overnight lows drop into the lower to middle 30s. Light snow will linger through Monday morning before coming to an end by midday as the trough axis dissipates. Despite an end to the precip, skies will remain overcast through the day. High temperatures will hover in the 30s, while brisk northwesterly winds create wind-chill readings in the teens and 20s. .LONG TERM...(Monday night through Sunday) ISSUED AT 230 PM CST Sun Dec 2 2018 Cloudy and cold weather will continue through Tuesday before the sun finally returns by Wednesday as upper heights begin to rise in advance of the next approaching short-wave trough. 12z Dec 2 models are in very good agreement with the track and timing of the wave, showing the strongest lift and deepest moisture passing through central Illinois late Wednesday into early Thursday. As a result, will introduce chance PoPs for snow west of I-55 late Wednesday night...then will go with high chance to likely PoPs across the board Thursday morning. The atmosphere will be cold enough to support mainly snow, with a transition to a rain/snow mix or all rain along and south of a Champaign to Shelbyville line by Tuesday afternoon as the precip begins to depart. Up to 1 inch of snow is expected along/north of the I-72 corridor. Once this system exits the region, cool/dry weather will prevail through the remainder of the extended. Will need to keep an eye on a southern stream system tracking across the Southern Plains on Saturday into the Deep South by Monday. Previous models had indicated precip from this feature may spread as far north as parts of central Illinois late Saturday into Sunday: however, the latest GFS and ECMWF now keep the precip much further south out of Illinois. Will continue to feature low chance PoPs across the far southern CWA over the weekend, but these will likely be removed pending support from another model run. Main weather story will be the continuation of below normal highs remain in the 30s through next Sunday. && .AVIATION...(For the 00Z TAFS through 00Z Monday evening) Issued at 537 PM CST Sun Dec 2 2018 MVFR/IFR ceilings will persist at the central Illinois terminals through the entire 00z TAF period. Latest radar imagery shows widespread light showers from just east of the Illinois River to the Indiana border. Based on radar loops and HRRR forecast, have included predominant -RA at KBMI through 02z, KDEC through 03z, and KCMI until 06z. After that, have maintained VCSH at all sites until Monday afternoon. Ceilings will hover in the IFR to low MVFR category through the night, then will gradually improve into the MVFR category from west to east across the area on Monday. && .ILX WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...Shimon SHORT TERM...Barnes LONG TERM...Barnes AVIATION...Barnes
Area Forecast Discussion...UPDATED
National Weather Service North Platte NE
530 PM CST Sun Dec 2 2018 .SYNOPSIS... Issued at 310 PM CST Sun Dec 2 2018 H5 analysis from this morning had a broad trough of low pressure across most of the CONUS. Closed low pressure was noted over southeastern Iowa with a shortwave trough extending to the west northwest into eastern Wyoming. Weak high pressure was noted over eastern Saskatchewan with another strong shortwave noted over southern Utah and other embedded shortwaves extending from this feature into western Nevada and northern California. Further east of this large trough, a low amplitude ridge extended from the western Atlantic into the Canadian Maritimes, while west of this trough, another ridge extended from the eastern Pacific north into the Gulf of Alaska and the Yukon. At the surface, low pressure was noted over southeastern Michigan with a cold front extending south to the Florida Panhandle. West of the low, an occluded front extended to the west into northern Illinois. High pressure was located over western Manitoba and northerly winds were present from eastern North Dakota into central and eastern Nebraska. Lighter winds were present across the Nebraska Panhandle this afternoon. Light snow continued to fall across portions of southwestern and Central Nebraska as of early afternoon. Accumulations with this were very light with hourly amounts of one to two tenths of an inch per hour. As of 3 PM CST, snow was present over southern Custer, eastern Lincoln and portions of eastern Frontier county. This activity is expected to push out of the area over the next 1 to 2 hours so the winter headlines will be cancelled with the 4 PM CST forecast issuance. && .SHORT TERM...(This evening through Monday) Issued at 310 PM CST Sun Dec 2 2018 Light snow will come to an end across southeastern forecast area by mid evening as forcing finally tracks east and southeast into sern Nebraska and northern Kansas. Only a dusting of additional accumulation will be possible and with winds expected to diminish by sundown, do not see headlines being extended into the evening. Otherwise, the models continue to advertise plenty of low level moisture overnight which will be favorable for clouds. That being said, lows tonight should be higher than the latest guidance which has lower teens and even some single digits in the northwest. Given the expected cloud cover, have opted for warmer than guidance lows tonight and didn`t deviate much from the inherited forecast. Looking at the latest NAM12 solution from this morning, light winds and a saturated boundary layer are depicted in this model tonight in the northwestern forecast area, which would be favorable for fog formation. The latest HRRR and NAM nest solutions lend support to fog in the northwest as well. That being said, will insert mention of patchy fog in the northwest tonight. High pressure will build south into eastern Nebraska on Monday. However, abundant low level moisture will persist across the forecast area on Monday, leading to cloudy to mostly cloudy skies for Monday. This will limit highs to the lower to middle 20s. .LONG TERM...(Monday night through Sunday) Issued at 310 PM CST Sun Dec 2 2018 Surface high pressure will drop south into the Ozarks Monday night shifting the winds to the west across the forecast area. This will dry out the boundary layer, however, mid and high level clouds will stream in from the northwest ahead of another approaching disturbance. Temperatures will be cool once again with highs struggling to reach the freezing mark. A stronger, upper level trough and arctic front will track into the northern plains early on Wednesday. Ahead of the front, warmer air will push into the forecast area from the west and southwest allowing highs to reach the middle to upper 30s. The warmup will be temporary though as the arctic front arrives on Wednesday evening. Not expecting much in the way of precipitation with the front as the best mid level forcing is east and southeast of the forecast area. For the remainder of the work week into Saturday, the forecast area will be well north of the arctic front. Highs will be in the lower 20s for Thursday and mid to upper 20s for Friday. By Saturday, highs will reach the upper 20s to lower 30s. The next chance for possible precipitation may move into southern Nebraska for Friday into Saturday. A nice southern stream trough of low pressure, will slide from the desert southwest into the southern plains and southeastern CONUS. The latest ECMWF and GFS solutions keep the best forcing with this system well south of the area. With that in mind, will continue with a dry forecast and warm highs into the 30s for next Sunday. && .AVIATION...(For the 00Z TAFS through 00Z Monday evening) Issued at 529 PM CST Sun Dec 2 2018 LIFR in fog is expected across Sheridan and Cherry counties tonight. Elsewhere across wrn and ncntl Nebraska, IFR/MVFR cigs continue overnight. An area of VFR is underway across parts of wrn Nebraska. This area of partial clearing is expected to remain stationary overnight. Flight conditions are expected to improve to VFR/MVFR from west to east Monday. && .LBF WATCHES/WARNINGS/ADVISORIES... None. && $$ SYNOPSIS...Buttler SHORT TERM...Buttler LONG TERM...Buttler AVIATION...CDC
Area Forecast Discussion
National Weather Service Marquette MI
600 PM EST Sun Dec 2 2018 .SHORT TERM...(This evening through Monday) Issued at 421 PM EST SUN DEC 2 2018 WV imagery and RAP analysis indicated a mid/upper level trough from James Bay to the mid Mississippi Valley with a prominent shortwave over northeast IL. Radars indicated diminishing snow over most of Upper Michigan as the supporting 800-600mb fgen/deformation weakens and slides to the south and east. However, the combination of lingering 850-600mb moisture, strong nne flow across Lake Superior and orographic lift into north central Upper Michigan has sustained moderate to heavy snow, despite 850 mb temps only around -6C. Snowfall totals around the NWS office. Closer to the shore totals were only a few inches at most. Over the west, the nne flow has also brought an increase in snowfall rates to KIWD. Tonight, Although CAA will bring slightly colder air into the region with 850 mb temps to around -10C to -12C, inversion heights near KMQT dropping to 6k ft by 06z and near 4k ft by 12z, along with 925 mb winds dropping to 25 knots will bring an end to the heavier lake and terrain enhanced snow. Since a couple more inches are expected at KIWD and up to 4-5 inches near KMQT, an advisory was issued for this evening for Gogebic county and the warning remains in effect for Marquette county. Otherwise, with weak synoptic forcing over the area additional accumulations over the rest of the area are expected to remain less than a half inch. Monday, Winds will diminish and back with increasingly anticyclonic flow. So, any remained snow will also diminish with some minor additional accumulations of less than an inch in the morning. Otherwise, temps will remain near seasonal averages with highs in the upper 20s to around 30. .LONG TERM...(Monday night through Sunday) Issued at 310 PM EST SUN DEC 2 2018 Shortwave finally departs the Great Lakes region, with weak ridging sliding east towards the Western Great Lakes for late Mon ngt. This should provide some drier air in the lower/mid-levels, bringing a brief break to any precipitation for the Upper Peninsula. Thermal trough will remain overhead, which will keep any precip in mainly dendritic or snow form. But as mentioned earlier, precip chances are going to be minimal for a brief period. Later Tue yet another weak mid-level trough will approach from the west, which will re-introduce some precip chances for the Upper Peninsula into Wed, and return a northwest flow with Lake Effect setup in the main snowbelts for later in the extended. Wed ngt guidance currently anticipates a stronger frontal boundary will arrive from the northwest, which will push high temps down further for Thur only reaching the teens to lower 20s Thur into Fri. Towards the end of the current extended periods guidance continues to hint that a shift in the pattern will start, with more of a quasi- zonal or west to east orientation. This pattern would suggest a trend towards drier setup and possibly a warming trend currently just beyond the extended. && .AVIATION...(For the 00Z TAFS through 00Z Monday evening) Issued at 600 PM EST SUN DEC 2 2018 MVFR conditions will remain for the forecast period at CMX. For SAW, VLIFR/LIFR conditions will be the prevailing conditions this evening with persistent lake enhanced/effect snow and blowing snow contributing to low visibilities with gusty winds. There will be some improvement to MVFR after midnight as the slightly drier air moves in at SAW. IWD will briefly be low MVFR Mon morning, otherwise will stay IFR. && .MARINE...(For the 4 PM Lake Superior forecast issuance) Issued at 421 PM EST SUN DEC 2 2018 As the pressure gradient weakens tonight winds will diminish to less than 30 kts late tonight and to less than 25 kts on Monday while gradually backing to the northwest. Later Monday afternoon through the middle of the week, winds will rotate back and forth between west and northwest at speeds of 15 to 25 knots. Next chance for stronger winds arrive on Thursday behind a stronger cold front. && .MQT WATCHES/WARNINGS/ADVISORIES... Upper Michigan... Winter Weather Advisory until 11 PM CST this evening for MIZ009. Lakeshore Flood Advisory until 7 PM EST /6 PM CST/ this evening for MIZ002-009. Winter Storm Warning until midnight EST tonight for MIZ004-005. Lakeshore Flood Advisory until 2 AM CST Monday for MIZ012. Lake Superior... Gale Warning until 2 AM EST Monday for LSZ248>251-265>267. Gale Warning until 1 AM EST Monday for LSZ243>245-264. Gale Warning until 11 PM EST this evening for LSZ246-247. Gale Warning until midnight EST /11 PM CST/ tonight for LSZ162- 240>242-263. Lake Michigan... Gale Warning until 5 AM EST Monday for LMZ221-250. && $$ SHORT TERM...JLB LONG TERM...Beachler AVIATION...07 MARINE...JLB
Area Forecast Discussion
National Weather Service Mount Holly NJ
930 PM EST Sun Dec 2 2018 .SYNOPSIS... Low pressure will move from the Great Lakes Region this evening down the Saint Lawrence Valley Monday. The associated cold front is expected to sweep through our region late tonight and Monday. High pressure will build in for much of the middle part of the week, although a few weak disturbances will also cross the area. A cold front will cross the area next Friday, followed by high pressure moving in for the beginning of next weekend. The next low pressure system may lift along the coast early next week. && .NEAR TERM /THROUGH MONDAY/... 930pm update: added Carbon/Monroe Counties to the Dense Fog Advisory as visibilities continue to trend downward as of this hour. Held off on an advisory in southern New Jersey and central/southern Delaware since visibilities remain above advisory criteria in these areas. Thinking areas south of the front, excluding marine zones, should maintain this trend. Showery activity also appears to have a downward trend as well, however may still see some showers firing along the frontal boundary that is stalled across the Delaware River Valley for the next few hours. Areas of light drizzle will also be possible until the arrival of the cold front later on tonight. Low temps south of the warm front might be a bit too cool, but most hi-res guidance indicates temps will begin falling later on tonight despite temps failing to fall much this evening. Previous discussion... Another question mark is the potential for some convective showers to develop along the southwest-northeast oriented front this evening. Both the HRRR and NAM Nest indicate this, mainly southeast of the Interstate 95/295 corridor through midnight. Indeed, a fairly strong temperature gradient exists here, as Kent/Sussex Counties in Delaware have warmed considerably (where greater mixing has developed). The associated stronger southwest winds have also led to modest convergence along this boundary, and with the approach of a strong vort max to our north/west this evening, sufficient large-scale lift should be in place to generate some showers. Although not completely out of the question, the thunder potential appears too low for mention at this point. Have increased PoPs in central/southern NJ and Delmarva to depict this threat. The cold front associated with the vort max and attendant surface low to the west-northwest begins to move through during the overnight hours, and this should advect drier air into the region as winds switch to westerly. This will be the end of the fog/low clouds across the area. Temperatures will remain fairly steady through the night, but will drop somewhat after the cold front moves through late. For Monday, as the surface low to our northwest lifts northeast along the Saint Lawrence River, west flow will become established in the northern Mid-Atlantic. Associated cold advection will counter the warming effects of downsloping and boundary-layer mixing. Skies will be partly to mostly sunny for most of the area (at least until the deeper mixing occurs during the afternoon, which may aid in the development of stratocumulus, especially in the northwestern CWA). The competing meteorological effects will mean high temperatures fairly similar to those seen today, except for central/southern Delmarva, where it will be decidedly cooler (by about 7-12 degrees). The main sensible-weather impact on Monday will be breezy winds, which may gust 25 to 35 mph during the day. Increased the wind forecast substantially given latest BUFKIT soundings and statistical guidance. && .SHORT TERM /MONDAY NIGHT THROUGH WEDNESDAY/... A rather quiet period is in store as a broad surface high slowly moves into the Southeast. The main question is what impacts a strong vort max moving through the central/southern Mid-Atlantic may have on our area Tuesday night and Wednesday. Model consensus seems to suggest showery precipitation will stay predominantly south of the area, though I cannot completely rule out a few in our southern areas. However, given the light look to the precip, short time window, and fairly strong consensus of the best lift being south of the area, kept PoPs non-mentionable through the period. Conditions may remain somewhat breezy on Tuesday as the pressure gradient does not completely relax given the building high pressure to our west/southwest and the retreating low in the Canadian Maritimes. Temperatures will be below seasonal averages, by around 6- 12 degrees, both Tuesday and Wednesday, with Wednesday being a little colder as warming effects from mixing/downsloping diminish. It may also be cloudier on Wednesday (than currently forecast) if the effects from the aforementioned vort max are greater than currently projected. && .LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/... A long wave mid level trough is forecast to settle over the eastern states for the period from Wednesday night through Friday. An initial short wave is expected to be located over our region on Wednesday evening. It should quickly move away to our east on Wednesday night. A second short wave and an accompanying surface cold front are anticipated to arrive on Thursday night. We will mention a low or slight chance of snow showers on Thursday night from around the Interstate 78 Corridor northward, otherwise it should be cold and dry from Wednesday night into Friday. The mid level long wave trough is expected to lift to our northeast on Saturday with a split flow becoming established over the Middle Atlantic states and vicinity for Sunday. Cold air to the north and moisture building up from the south should result in some wintry precipitation. Presently, the guidance is suggesting the the resulting surface low will be along the Southeast coast on Sunday with the precipitation remaining to our south at that time. However, it is expected to begin progressing up the coast for Monday the 10th and it is definitely a system to monitor in our region for the beginning of next week. && .AVIATION /02Z MONDAY THROUGH FRIDAY/... The following discussion is for KPHL, KPNE, KTTN, KABE, KRDG, KILG, KMIV, KACY and surrounding areas. Tonight...Generally IFR/LIFR through about 09Z to 11Z when a cold front is expected to begin scouring out the low level moisture. There is a chance of showers until 03Z mainly around KMIV and KACY. Southwest wind 8 knots or less becoming west around 10 knots after 09Z. Monday...Mainly VFR. Scattered clouds in the morning with a deck of stratocumulus expected in the afternoon (bases 4000 to 5000 feet). Westerly wind 10 to 15 knots with gusts of 20 to 25 knots. Outlook... Monday night through Wednesday...Predominantly VFR with breezy west to northwest winds Tuesday (10 to 15 kts with higher gusts) and lighter winds on Wednesday (5 to 15 kts). However, a nearby storm on Wednesday lends to some uncertainty regarding the sky conditions and winds in our area. High confidence Tuesday; low confidence Wednesday. Wednesday night...Mainly VFR. Northwest wind 5 to 10 knots. Thursday...Mainly VFR. West to southwest wind 5 to 10 knots. Thursday night...Mainly VFR. Southwest wind 5 to 10 knots becoming northwest. Friday...Mainly VFR. Northwest wind 10 to 15 knots. && .MARINE... Dense fog continues on the Atlantic coastal waters and Delaware Bay. Extended dense fog advisory through the night, with improvement expected thereafter thanks to a cold-frontal passage. Winds on the waters have been sub-advisory today, but seas are elevated. This should generally hold through tonight, but as a cold front moves through, directions will turn westerly and gusts will increase to 25 to 30 kts on Monday. Small craft advisory is in effect for the Atlantic waters through Monday. Sub-advisory conditions should occur on Delaware Bay. There is a chance of showers this evening, and a rogue lightning strike cannot be ruled out. Winds/waves may become erratic near any showers that develop. Outlook... Monday night...Lingering advisory-level northwest winds on the Atlantic waters through much of the night. Small craft advisory was extended through the night. Tuesday and Wednesday...Sub-advisory winds/seas. Fair on Tuesday, but showers cannot be ruled out on Wednesday, especially in the southern portions of the Atlantic waters. Wednesday night and Thursday...No marine headlines are anticipated. Thursday night and Friday...A northwest wind may gust to 25 or 30 knots. && .PHI WATCHES/WARNINGS/ADVISORIES... PA...Dense Fog Advisory until 4 AM EST Monday for PAZ054-055- 060>062-070-071-101>106. NJ...Dense Fog Advisory until 4 AM EST Monday for NJZ001-007>010- 012>015. DE...Dense Fog Advisory until 4 AM EST Monday for DEZ001. MD...Dense Fog Advisory until 4 AM EST Monday for MDZ008. MARINE...Dense Fog Advisory until 6 AM EST Monday for ANZ430-431- 450>453. Small Craft Advisory until 6 AM EST Tuesday for ANZ450>455. && $$ Synopsis...CMS/Fitzsimmons/Johnson Near Term...CMS/Staarmann Short Term...CMS Long Term...Iovino Aviation...CMS/Iovino Marine...CMS/Iovino
Area Forecast Discussion
National Weather Service Pocatello ID
730 PM MST Sun Dec 2 2018 .SHORT TERM...Tonight through Wednesday. A second update this evening as the latest 00z NAM12 and HRRR are indicating widespread light snowfall continuing across the SE mountains including Cold Water to Pocatello to Shelley overnight. Have boosted precipitation potential and snow accumulations as a result. Totals still remain below advisory levels. See previous discussion below for additional information. Huston Persistent snow lingers along and south of Interstate 86. Snowfall intensity is pretty light given the lack of upper-level dynamic support. However, surface convergence and upslope flow should sustain this area of now through tomorrow. A weak upper trough will swing through tonight, lifting the area of snow northeastward into the Driggs and Island Park areas, and as far south as Bear Lake. Snow in the Central Mountains tomorrow will continue due to orographic lift, though intensity will remain light for most areas. Mountain passes will see about 1 to 3 additional inches of snow through tomorrow afternoon. Monday and Tuesday will see the upper low moving out of the area while another upper low approaches from the California coast. Models are keeping precip right along our southern border Tuesday night and Wednesday. NAM lifts the precip a little further northward, but doesn`t progress it much further northward than the I-86 corridor. Hinsberger .LONG TERM...Wednesday night through Sunday. Complex forecast continues to remain on tap for the beginning of the extended portion of the forecast, as SE Idaho remains sandwiched between stout NW flow and embedded disturbances flowing east of the Divide, and a broad low centered over California. Ejecting out of this low will be a lead disturbance and its associated band of light snowfall, whose evolution is still looking difficult to pin down. The question that remains much Snow will make it into Idaho from the south? Recent trends continue to suggest a southerly adjustment to the forecast is needed -- and have followed that trend. We`re now carrying light Snow chances late Tue-Thu for those areas adjacent to the Utah border, including Malad, Preston and Bear Lake. Recent trends suggest we may need to narrow the timing as well, as it now appears Wednesday will see the highest probability of seeing Precipitation. Overall amounts appear to be on the light side. After this disturbance moves away, a ridge of high pressure is then forecast to gradually build over the region from late Thursday through next weekend. The drying trend that began to emerge on yesterday`s guidance for next weekend continues, and am now carrying dry conditions most areas (except for a sneaky snow shower or two around Island Park) through next weekend. As a result of the high pressure in place across our region, the sprawling and moist Pacific trough that moves ashore early Sunday is forced to make only slow eastward progress, and latest indications suggest any Precipitation associated with this system will hold off until next Monday, mainly over the Central Mountains. Continuing to forecast seasonably cold Temperatures through the week, with Temperatures 10-15 degrees below climatology for this time of year. This means sub-freezing highs and numerous single digit lows for the Snake Plain, with below zero lows for high elevation valleys. Cloud cover near the Utah border should keep lows `warmer` there until that cloudiness moves out late-week. We`ll begin to see a warming trend develop next weekend, which will be most pronounced above the inversions at mid and upper slopes. We`ll likely need to wait until early next week for any pronounced warming in valleys with the approach of the next trough. As a result of the inversions, patchy fog will be possible in valleys along with deteriorating air quality through the week. AD/Hinsberger && .AVIATION...Low confidence TAF forecast continues. Broad cyclonic flow remains in place over the region, with weak surface convergence aiding to focus snow showers in a north-south oriented band from SUN south to between BYI and PIH. Have seen conditions improve at BYI to MVFR, and most guidance suggests this condition will persist into Monday morning. However, there is extensive IFR stratus in place to the west across the Magic and Treasure valleys, and the westerly flow may allow this to advect into the terminal overnight. For PIH, the MVFR stratus and associated light Snow shower activity has arrived ahead of schedule, and MVFR to occasionally IFR CIGS expected to persist into Monday morning with occasional SHSN. With the southwest flow forecast to overspread the Snake Plain, high resolution guidance allows this stratus deck to move into IDA between 06 and 09Z, and begin to rapidly drop CIGs at this point. Will need to continue to monitor this progression. May see some of this move into DIJ as well, but am carrying the most optimistic conditions here. For SUN, MVFR CIGs in place now, and may see these drop to airfield minimums late this afternoon through early evening as reservoir of stratus and SHSN may advect in from the south. Should see some improvement in conditions here late-night but again confidence is quite low on the details and future amendments will likely be needed. AD/Hinsberger && .PIH WATCHES/WARNINGS/ADVISORIES... None. && $$
Area Forecast Discussion
National Weather Service Tulsa OK
803 PM CST Sun Dec 2 2018 .UPDATE... Main update was to insert some low PoPs down near the Red River after midnight tonight. See discussion below. && .DISCUSSION... As discussed earlier, an approaching upper wave, which is also increasing clouds this evening over the region, will also help to enduce frontogenesis in the 850-600MB layer tonight, mainly along/near the Red River valley. The latest runs of the HRRR suggest that some light rain could develop as far east as southern Choctaw county, and have thus raised PoPs to slight chance. Otherwise, no other changes needed as trends in other data look good. Surface high pressure is building quickly southward out of central Canada and down the Plains, and this will bring a reinforcing push of colder air into the region. An even colder day is forecast on Monday. Lacy && .PREV DISCUSSION... /Issued 550 PM CST Sun Dec 2 2018/ AVIATION... CONCERNING TAF SITES KTUL/KRVS/KBVO/KMLC/KXNA/KFYV/KFSM/KROG. VFR ceilings will continue to threaten KBVO and far northern AR TAF sites this evening as mid level clouds advance from the west ahead of next system over northern NM. Dry low levels should keep VFR conditions in place at KMLC and KFSM through the period. Reinforcing cold surge associated with secondary northern stream system however will bring MVFR ceilings to northern OK and AR terminals after midnight. With system slow to eject expect low clouds to remain in place much of the day Monday. Generally light northwest winds expected overnight with speeds closer to 10kt during the day Monday. PREV DISCUSSION... /Issued 315 PM CST Sun Dec 2 2018/ DISCUSSION... The main forecast concerns center on a storm system that will affect the region late this week into next weekend. Heavy rainfall and winter weather potential will accompany this system. A challenging forecast lies ahead in the days to come. I will touch on this later. Models for several days have suggested that a band of very light precip will spread east along/near the Red River valley late tonight. This appears to be forced by 850-600 mb cold frontogenesis, as a lobe of PV slides across the Plains at the base of the broad and deep upper trough over the CONUS. However, models show a fairly dry sub-cloud layer with only light precip falling into this layer. Also, the forcing weakens and shifts southeast by the time this precip would extend into SE OK. As a result, I`m going to maintain a dry forecast for the Red River valley region for tonight. Reinforcing push of colder air arrives tonight as surface high pressure over central Canada slides south down the Plains in the wake of the departing storm system. High temps Monday will be a good 10 degrees colder than today. Now to the meat of this forecast. A split flow pattern currently exists over the eastern Pacific to the west of the broad CONUS upper trough. As this blocking pattern breaks down by the middle of this week, a strong system in the southern stream will move into southern CA Thursday and then quickly east across the southern tier of states thru next weekend. The system will tap plentiful Gulf moisture to the south and will produce a fairly significant precip event over the south central states Friday into Saturday. In fact, more than an inch of precip is forecast over the ArkLaTex, SE OK and WC AR. So part 1, the moisture, is a given. It will precip. Now to part 2, thermal structure of the environment when this precip is falling. This will be by far the most challenging part of the forecast, as it usually is in complex winter weather scenarios. The GFS has trended colder and closer to the ECMWF, and will use a blend of the thermal profiles for this forecast. As such, the transition zone between liquid and frozen precip will dissect the forecast area, with obviously rain in the south and a mixed bag of winter types to the north. It is worth noting that there are differences in the northward extent of the warm layer between the GFS and ECMWF. Given that the event is still several days out, a blend is the better approach for now. Since the ECMWF handles low level cold air better typically, I leaned more heavily on the raw surface temps for this forecast. The end result and main point remain the same. The potential for a significant winter weather event across a good chunk of the area remains. The details of which will continue to be refined in the coming days. Lacy && .PRELIMINARY POINT TEMPS/POPS... TUL 29 40 23 42 / 0 0 0 0 FSM 33 45 27 44 / 0 0 0 0 MLC 33 44 25 44 / 0 10 0 0 BVO 29 39 21 40 / 0 0 0 0 FYV 29 38 21 38 / 0 0 0 0 BYV 30 38 23 36 / 0 0 0 0 MKO 32 42 24 42 / 0 0 0 0 MIO 28 38 22 38 / 0 0 0 0 F10 30 42 23 43 / 0 10 0 0 HHW 37 49 27 47 / 10 10 0 0 && .TSA WATCHES/WARNINGS/ADVISORIES... OK...None. AR...None. && $$ LONG TERM....30