Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 11/20/18

Area Forecast Discussion
National Weather Service Boston/Norton MA
1023 PM EST Mon Nov 19 2018 .SYNOPSIS... Developing storm center tonight through Tuesday night will bring accumulating snows mainly along and N of the MA-Turnpike, impacting the Tuesday AM commute for some. Otherwise an all rain or rain/snow mix. Colder weather follows for Wednesday into Friday, with the possibility of some snow squalls Wednesday. && .NEAR TERM /UNTIL MIDNIGHT TONIGHT/... 1015 PM Update... Front sitting well off our south coast. Regional radar shows the heaviest band of precip draped northeast from Hartford county to Essex county. Previous hi-res solutions showing a bit of a lull behind the initial line are panning out well...seeing a bit of a break behind the initial heavier precip. Obs in Berkshire county show the snow from the past several hours has stopped. In our area the only observation indicating snow at this hour is KORE in north central MA, with rain at all other observation sites. This matches up well with forecast over the next several hours. No major changes. Most of the impacts from this system are expected along and north of the MA pike. Previous Discussion... Main change with this forecast update is to speed to speed the timing of the POPs, initial overruning precip is moving across the area N of a BDL-ORH-BVY line with mixed RA and some SN in the high terrain along the Berkshires. Watching trends suggest this first round may actually dissipate in response to continued deepening of the low pres upstream as it approaches. HRRR seems to suggest this as well, so POPs will actually decrease a bit initially until the stronger lift associated with the developing frontal wave moves in during the early AM hours. Otherwise, based on latest mesoscale guidance, see no need for significant changes to snowfall amounts and headlines as they stand. && .SHORT TERM /MIDNIGHT TONIGHT THROUGH TUESDAY NIGHT/... Tonight through Tuesday... Strengthening storm system across New England bringing accumulating around 3-inch snows mostly N of the MA Turnpike, especially the high terrain. Tuesday AM travel impacts with reduced visibility and snow on area roadways for those areas noted. Synoptically. Initial low sweeps New England with maturation further downstream. Mainly open wave, not so much closed H925-85, tracking over interior New England around the MA / VT / NH border, low level convergent focus of the anti-cyclonic warm-moist conveyor belt out ahead of a digging, sharpening mid-level trof axis and accompanying vortmax energy. Initiated low to mid level thermal packing as well as deformation / frontogenesis beneath mid-level ascent and initial diffluence aloft, majority low-level forcing up thru the dendritic growth zone, H6-7, so not impressively deep. Omega values through the column weak, especially through the dendritic growth zone which happens to exhibit some fairly steep lapse rates. Overall, a decent front-end thump leading out ahead of the surface to H85 low. The storm becomes better organized through Tuesday as it exits into the Gulf of Maine having swept across the Cape Cod Canal around 1 pm. Challenges. Thermal fields / thickness tell the story. Right on the freezing cusp with deeper Arctic air absence N, hardly a N/NE high over Canada. While N isallobaric flow, it`ll only drain S surface temperatures ranging around 30 with dewpoints a tad lower such that wet-bulbing can only do so much. Low-level column nearly isothermal up through H8, warmer air intruding as the H925-85 flow flutters along the MA / NH / VT border, possibly some drier air working in through the dendritic growth zone, while fluttering around freezing as the event evolves into the daylight hours, dealing with forecast headaches concerning precipitation types and snowfall accumulations as well as snowfall intensity. Speaking of, as model forecast mass fields look pretty similar, small-scale focusing forcing mechanisms vary as discerned via model forecast plume diagrams. Considerable spread in respect to liquid-equivalent precipitation and snowfall, the latter ranging from sub-advisory to warning levels in particular locations. Relates back to snowfall intensity, some low probability of 1"/hr noted in high-res guidance, and thermal field alignment as to where the rain / snow cut-off line will be at any one particular time. Forcing majority is, however, below the dendritic growth zone with this synoptic setup. Of last note, model forecasts assume that everything which falls accumulates on the ground which we know is not always the case. So it`s definitely not easy but we`re going to do our best as we always do. Decisions. Despite uncertainties and challenges noted, a consensus weighted forecast does not seem like a bad idea. Gave greater weight towards the HREF blended within. With probabilities noted, and the 19.12z forecast suite slightly jogging S, focus is around the MA / NH / VT border. Coating N of the MA-pike, with 1-3" lower elevations while 3-6" higher, 500 feet and above especially. Potentially near warning-level snows up around the N MA towns of Ashburnham, Ashby, and Townsend. Keep with present N/W MA WINTER WEATHER ADVISORIES. The storm center sweeping NE across the Cape Cod Canal important with respect to blustery N/NE winds out ahead. Impacts. Expect hazardous travel over N/W MA especially the higher terrain of Worcester Hills and Berkshires. Route 2, western-half of MA I-90, N MA I-95, I-190 out of Worcester, and the NW beltway of 495 all have the risk of accumulating snows on roadways. Reduced visibility as well especially within any moderate to heavy snow as near 1"/hr snowfall rates are possible. Thinking a very low risk of any mixed wintry precip-types mainly in the form of freezing rain. Tuesday night... Turning colder and drier. The storm continuing to deepen into the Gulf of ME, blustery NW winds follow. Some lingering snow showers possible, especially for the high terrain. Otherwise the main storm is the driving cold along with breezy conditions that`ll make it feel 5 to 10 degrees colder than the forecast nighttime lows around the low to mid 20s, possibly upper teens for the high terrain. && .LONG TERM /WEDNESDAY THROUGH MONDAY/... 4 AM update... Highlights... * Arctic front late Wed with snow squalls possible * Near record cold & bitterly cold wind chills Wed night/Thanksgiving * Moderating temps and dry Friday into Saturday * Wintry weather possible Sunday Overview and model preferences... The longwave trof which has been a persistent player in the daily sensible wx across the northeast finally gets a break later this period, but not before one last push of cold air. Two mid lvl cutoffs Fujiwhara near Hudson`s Bay with one and its attendant vort-max sliding close to New England Wed into Thu. The surface reflection is an arctic cold frontal passage Wed. This ushers in a very anomalous airmass with H85 temps nearly -20C below seasonal normal values which will be with us for Thursday into Saturday. Upper lvl ridge finally shifts E, shifting the trof offshore by the weekend. However, it too flattens as a second wave, linked more closely to the southern stream per latest guidance moves in late weekend into early next week. Given the guidance has been in fairly good agreement with this arctic influenced pattern a consensus blend will be used except for temperatures, which will feature the coldest of the guidance Wed-Fri. Details... Wed... Arctic cold frontal passage linked to acute, cyclonically- curved shortwave rotating through the base of the longwave trof mentioned above. The main issue will be the risk for snow squalls. Soundings indicate a sfc-H7 which is both moist and with potentially higher than dry-adiabatic lapse rates. With this implied instability, cold air aloft and strong dynamic cooling in play, could very well see brief bursts of heavy snow impacting commuters. LLJ at the top of this well mixed layer is around 40 kt, which could mix down some of this momentum to accompany the snow. Hence the risk for squalls, this will be something to watch given the typically busy travel day. Thu... Core of cold air working E but as nearly 1040mb high pres and deepening low pres in the Maritimes combine to yield strong pres rises note very breezy 20-30 kt winds at times as well. Ambient mixed temps will struggle to break out of the teens and low 20s, but with winds, expecting chill values int the single digits to near 0F. With pres gradient weakening late Thu night, some radiational cooling should allow ambient 2m mins to drop into the single digits as well. Ocean effect SN for the outer arm of the Cape particularly thanks to +15C SST-H85 delta-T values. Fri and Sat... Core of high pres slides across New England with the continuation of dry wx. Temps moderate but remain well below normal on Fri, with highs only making it into the upper 20s to low 30s. Overnight mins still cold given good setup for radiational cooling once again. Highs moderate further Sat, reaching the low-mid 40s thanks to increase in mid lvl temps. Sun into Mon... Will be monitoring low pres development in convection near the Gulf of Mexico, linked to a S stream shortwave. The track of this feature is still uncertain given wide model spread and the features not well sampled at this time. This will dictate whether its an inland passage (warmer solution) or offshore track (colder, but also a risk for a miss). Exact p-type details will be worked out with time. && .AVIATION /03Z TUESDAY THROUGH SATURDAY/... Forecaster Confidence Levels... Low - less than 30 percent. Moderate - 30 to 60 percent. High - greater than 60 percent. Short Term /through Tuesday Night/...High Confidence. Tonight and Tuesday... Mainly VFR vsby with mixed MVFR/VFR CIGS through about 04Z south of a line from BDL-ORH-BVY. Areas N will mix MVFR/IFR in light RA/SN through this time. After 04Z, trend will be toward mainly IFR all sites except immediate S coast due to lowered CIGS. VSBYS MVFR/IFR in SN mainly along and N of the Mass Pike with RA to the S. This continues into Tue with some improvement after 18Z, slowly from W-E. Winds N-NE. Tuesday night... Winds shifting NW as conditions improve towards VFR, the 18z storm center lifting out into the Gulf of ME. Gusts up to around 25 kts possible especially over the high terrain and along coastline terminals. KBOS Terminal... Moderate confidence, mainly due to uncertainty in timing of lower categories/precipitation. VFR conditions to gradually give way to MVFR then IFR with lowered CIGS then vsbys as a mix of RA/SN develops late tonight. Mainly RA into tomorrow but a brief change back to SN is possible late tomorrow afternoon before the precip ceases entirely. KBDL Terminal... VFR gives way to mixed MVFR then IFR within the next 3-4 hours. RASN mix right through the Tuesday morning push, becoming all rain towards midday. Mostly IFR, improving MVFR to VFR late Tuesday into Tuesday evening. N winds throughout shifting NW late. Somewhat breezy, especially late with potential gusts up to 20 kts. Outlook /Wednesday through Saturday/... Wednesday: Mainly VFR, with local IFR possible. Windy with gusts to 35 kt. Isolated SHSN. Wednesday Night through Thanksgiving Day: VFR. Windy with gusts to 35 kt. Thursday Night: VFR. Windy with areas gusts to 30 kt. Friday: VFR. Friday Night: VFR. Breezy. Saturday: Mainly VFR, with areas MVFR possible. Chance SHRA or SHSN. && .MARINE... Forecaster Confidence Levels... Low - less than 30 percent. Moderate - 30 to 60 percent. High - greater than 60 percent. Short Term /through Tuesday Night/...High confidence. Storm center passing over the Cape Cod Canal around 18z Tuesday. Will see increasing E/NE winds out ahead especially over the E waters, S/SW for the S waters. Behind the storm center, winds turning NW, remaining blustery. Throughout, gusts up around 25 kts possible. Can`t rule out near gale force gusts. SMALL CRAFT HEADLINES in effect for the later-half of Tuesday going into Tuesday night as seas build up around 5 to 7 feet on the outer waters. Outlook /Wednesday through Saturday/... Wednesday: Low risk for gale force winds with gusts up to 35 kt. Seas up to 5 ft. Isolated snow showers. Local visibility 1 to 3 nm. Wednesday Night: Moderate risk for gale force winds with gusts up to 40 kt. Rough seas up to 10 ft. Isolated snow showers. Areas of visibility 1 to 3 nm. Thanksgiving Day: Strong winds with gusts up to 35 kt. Rough seas up to 10 ft. Isolated snow showers. Areas of visibility 1 to 3 nm. Thursday Night: Moderate risk for Small Craft Advisory winds with gusts up to 30 kt. Local rough seas. Local visibility 1 to 3 nm. Friday: Winds less than 25 kt. Seas locally approaching 5 ft. Friday Night: Winds less than 25 kt. Saturday: Winds less than 25 kt. Slight chance of rain showers. && .CLIMATE... With the potential of the coldest air of the season moving into the region around Thanksgiving, here are the record temperatures for November 22nd and the holiday of Thanksgiving. November 22nd Location / Record Low / Record Minimum High Boston..........9 (1879) / 24 (1880) Hartford.......14 (1969) / 27 (1978) Providence.....16 (1987) / 30 (2008) Worcester......11 (1987) / 24 (2008) Thanksgiving Location / Record Low / Record Minimum High Boston.........11 (Nov 27, 1873) / 24 (Nov 28, 1901) Hartford.......12 (Nov 28, 2002) / 27 (Nov 23, 1989) Providence.....14 (Nov 23, 1972) / 30 (Nov 28, 1996) Worcester.......9 (Nov 23, 1989) / 22 (Nov 23, 1989) && .BOX WATCHES/WARNINGS/ADVISORIES... CT...None. MA...Winter Weather Advisory until 5 PM EST Tuesday for MAZ002>004- 008-009-026. RI...None. MARINE...Gale Watch from Wednesday evening through Thursday morning for ANZ231>234-251. Small Craft Advisory from 4 PM Tuesday to 4 AM EST Wednesday for ANZ232>234. Small Craft Advisory from 1 PM Tuesday to 1 AM EST Wednesday for ANZ231-251. Gale Watch from Wednesday afternoon through Thursday morning for ANZ235-237. Small Craft Advisory from 4 PM Tuesday to 6 AM EST Wednesday for ANZ235-237. Gale Watch from Wednesday afternoon through Thursday evening for ANZ250-254>256. Small Craft Advisory from 10 AM Tuesday to 6 AM EST Wednesday for ANZ250. Small Craft Advisory from 1 PM Tuesday to 6 AM EST Wednesday for ANZ254>256. && $$ SYNOPSIS...Doody/Sipprell NEAR TERM...Doody/BW SHORT TERM...Sipprell LONG TERM...Doody AVIATION...Doody/Sipprell MARINE...Doody/Sipprell CLIMATE...
Area Forecast Discussion
National Weather Service Hastings NE
559 PM CST Mon Nov 19 2018 .SHORT TERM...(This evening through Tuesday) Issued at 350 PM CST Mon Nov 19 2018 Aloft: WV imagery/upr-air data and aircraft obs showed a highly- amplified longwave pattern over the CONUS...with a ridge in the W and a broad trof extending from Hudson Bay to OK. Thru tomorrow these features will move E and deamplify a bit. So NW flow will remain over the Cntrl Plns with heights rising about 80 m at 500 mb. Surface: Weak low pres was over MI with a cold front extending back across IA thru the Neb Sandhills then NW into Wrn Canada. This front will briefly sag SW into the CWA tonight. However...a weak Clipper will slide down the front to near Lk Winnipeg tonight and then into the GtLks tomorrow. As a result...the front over the CWA will move E out of the CWA as a warm front tomorrow morning. Meanwhile...high pres was over ND at 20Z and it will slide SSE across Ern Neb/KS tonight. Now thru sunset: P-M/cldy. Temps overachieved today...but they have leveled off with the increased cld cover. LNX radar showed some spotty light returns over the Sandhills... and ANW did report some sprinkles. Can`t discount a few sprinkles moving into areas N and W of the Tri-Cities as these returns are moving SSE. Tonight: Quite a bit of uncertainty for period 1 of the fcst. Multi-model cross sections show a lot of RH below 10K ft suggesting that stratocu will hang around thru much of the night for parts of the CWA. Unusual as at least some of this is diurnally driven. Should be another cold night with lows mostly 19-24F. Areas of fog could be a problem. There is quite a bit of spread between mdls that are fcstg fog and those that are not...and am a bit uncomfortable that the mdls that usually handle fog the best (GFS MOS and LAMP) don`t have it. That being said...conds appear favorable. Dwpts are in the low-mid 30s and temps are fcst to crash way past the cross-over temps. The developing warm front is also a concern. For now...used vsbys from consensus of short-term mdls to include fog W of Hwy 281 mainly over S-cntrl Neb. Keep in mind there is considerable uncertainty in coverage and how low vsbys might be (if fog actually forms). This could be a serious weakness in this fcst. Tue: If any fog could take most of the AM to dissipate given the low sun angle. Otherwise sunny...or becoming sunny. Warmer with temps rebounding to a little above normal (mostly 50s). .LONG TERM...(Tuesday night through Monday) Issued at 257 PM CST Mon Nov 19 2018 Aloft: The longwaves will cont to be progressive thru this wknd. The last 2 runs of the EC/GFS/GFS-parallel/GEM/UKMET all fcst the ridge over the Rckys to crest over the Cntrl Plns Thu AM. The trof currently over the E Pac will be making its way E and will arrive here Fri AM. That trof will establish a longwave trof over the Cntrl USA thru the wknd. A low is fcst to drop out of the GlfAK and arrive here Sat-Sun where it could deepen over OK or KS. There is a lot of spread in how the mdls are handling that Sat- Sun system. The 00Z/12Z EC and 12Z/UKMET are the strongest with a closed low. The 12Z GFS-parallel is also in that camp. The 06Z/12Z GFS and 00Z/12Z GEM keep the trof open. See below for commentary on the sensible wx. Surface: The CWA will remain in the warm sector Wed-Thu. A Pac cool front moves thru Fri. An Arctic front will then plunge S out of Canada Sat while lee cyclogenesis begins over CO. That front should arrive Sat night and wrap into the low ejecting out of CO. High pres will build in Mon as this low heads across the GtLks. Temps: About 10F above normal Wed-Fri for daytime highs which translates to widespread 50s..and even some low 60s W of Hwy 183. Back to normal Sat...then 10-15F colder than normal Sun-Mon with highs in the 30s. Precip: A bit of light rain possible Thu night into Fri ahead of the cool front. Some light rain is possible Sat changing to snow Sat night. Could we have a winter storm (accumulating snow) Sat night into Sun? It`s possible. The op EC remains the most aggressive with this scenario. However...only half of the 00Z EC ensemble members bring accumulating snow to the CWA. So even though the op runs are aggressive...there are many ensemble members that are not. How this sys evolves aloft will have major implications on the fcst...and possibly important impacts for holiday travelers returning to the rgn Sun. Suggest everyone pay attention to the wx and monitor future fcsts. && .AVIATION...(For the 00Z KGRI/KEAR TAFS through 00Z Tuesday) Issued at 555 PM CST Mon Nov 19 2018 Confidence is lower than normal on ceiling and visibility conditions late tonight into Tuesday morning given the possibility of fog. The SREF is showing a pretty good chance for fog especially from KEAR west, but the HRRR has not been showing much fog potential. Will call for VFR conditions for now with limited confidence, but if fog does develop this TAF will need some big adjustments. && .GID WATCHES/WARNINGS/ADVISORIES... NE...None. KS...None. && $$ SHORT TERM...Kelley LONG TERM...Kelley AVIATION...Wesely
Area Forecast Discussion
National Weather Service Green Bay WI
533 PM CST Mon Nov 19 2018 Updated aviation portion for 00Z TAF issuance .SYNOPSIS... Issued at 222 PM CST Mon Nov 19 2018 Rather quiet but chilly weather will continue through Thanksgiving Day, with minimal weather-related problems expected as holiday travelers head out across the area. Warmer weather is expected for the rest of the holiday weekend, with an increasing chance for precipitation as well. The upper flow across North America will become progressive as flattening flow to the west allows Pacific energy to drive eastward across the continent. The change will initially lead to a less amplified and more zonal flow by the weekend. But that is expected to transition into a highly split flow regime over central and eastern North America next week. Temperatures will remain below normal for a couple more days, begin to warm on Thanksgiving, then spend at least a couple days above normal. The developing split flow next week is likely to be characterized by strong blocking over eastern Canada. That will probably lock a southern stream trough in over the Great Lakes region, forcing temperatures back below normal by the end of the period. Little consequential precipitation is expected until the weekend, when a complex/disjointed looking system is likely to bring widespread light to perhaps moderate precipitation to the area. At least initially, temperatures will probably be mild enough for primarily rain in the south and rain or a wintry mix in the north. The best estimate is for near or slightly below normal precipitation amounts for the period. && .SHORT TERM...Tonight and Tuesday Issued at 222 PM CST Mon Nov 19 2018 The latest RAP analysis and satellite/radar imagery show an area of low pressure moving east over northern Lower Michigan, and an associated cold front exiting east-central WI early this afternoon. Light snow associated with the system has departed to the east. Meanwhile, after a brief period of clearing right behind the front, boundary layer instability combined with moisture fluxes off Lake Superior are pushing additional cloud cover south over much of the area. Some flurries or light snow showers will be possible over far northern WI through the end of the afternoon. Until the next weak clipper arrives on Tuesday afternoon, forecast concerns mainly revolve around clouds and temps. Tonight...North flow will continue through the evening behind the low pressure system. With loss of diurnal instability, think gradual clearing will take place over parts of central and northeast WI, but delayed it until late evening and overnight. However, north- central WI will likely have to wait until late tonight or into Tuesday morning for clearing to occur when winds back around to the west and allow for some drier air to push into that area. Will keep isolated to scattered snow showers in the forecast for Vilas county due to lake effect. Boundary layer winds will lighten through the night, and if any clearing occurs across the north, think temps have potential to tank. But given the expansive blanket of clouds, stayed conservative with temps. Lows expected to range from the mid single digits north to the upper teens near the Lake. Tuesday...Scattered to broken low clouds may linger over far northern WI for a few hours in the morning. Otherwise, the surface ridge axis will quickly move across the area into early afternoon, which should result in some sunshine over eastern WI. However, clouds will be rapidly returning ahead of the next clipper and cold front which will be moving into northwest Wisconsin in the afternoon. Moisture is extremely limited, but most models generate about a half inch of snow for the northwoods during the afternoon. Some slippery roads are possible, mainly over Vilas and Oneida counties. Highs are forecast to range from the lower 20s north to the lower 30s over the southern Fox Valley. .LONG TERM...Tuesday Night Through Monday Issued at 222 PM CST Mon Nov 19 2018 With the large scale pattern becoming progressive, the best forcing with the system digging southeast from Canada Tuesday night will pass north of the area. Continued similar to the previous forecast in having chance PoPs in the north into the evening, with a period of lake-effect likely in the Lake Superior snowbelt overnight as the system pulls off to the east. It still appears possible that a little FZDZ could occur as the system departs and moisture becomes increasingly shallow. Models seem to be picking up on the possibility of some lake- effect off Lake Michigan affecting the east Wednesday night and Thursday morning as winds shift around to the east. But a very strong inversion around 850 mb should prevent anything more than flurries or light snow showers. The medium range models continue to struggle discerning the details of the system or series of systems likely to affect the area during the weekend and early next week. The flow will be starting to separate as the split becomes more pronounced. That is likely to keep the best southern stream dynamics and moisture south and east of the area. There will probably be a few rounds of light precipitation, the last of which may be a prolonged period of light snow or snow showers early next week as an upper trough gets locked into the Great Lakes region. Overall, no significant changes were necessary to the standard forecast initialization grids. && .AVIATION...for 00Z TAF Issuance Issued at 533 PM CST Mon Nov 19 2018 Abundant cloud cover will continue across the western Great Lakes this evening behind a cold front. Some LES showers will continue across the north this evening, before diminishing later tonight. Some drier air is forecast to clear skies out later tonight across central and east-central Wisconsin as ridging makes its way in from the west. Skies across the north should remain mostly cloudy throughout the period. There is some question as to when the clearing will take place as not all models clear the area out later tonight into Tuesday morning. If the clearing does occur it will cloud back up Tuesday afternoon as another clipper system tracks through the western Great Lakes region. This clipper system could bring some light snow or even some freezing rain, mainly across north- central and central Wisconsin. At this point will leave out the freezing drizzle potential as it is fairly low with this issuance. MVFR cigs are expected across the north through tonight, then briefly rising to VFR later Tuesday morning into the early afternoon before falling again to MVFR. Further south mainly VFR conditions are expected through the period, with some MVFR possible early this evening. && .GRB WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS.......Skowronski SHORT TERM.....MPC LONG TERM......Skowronski AVIATION.......Kurimski
Area Forecast Discussion...UPDATED
National Weather Service Gray ME
1043 PM EST Mon Nov 19 2018 .SYNOPSIS... Weak low pressure will track east along a stalled frontal boundary over southern New England late tonight through Tuesday. Low pressure will continue east into the maritimes Tuesday night. An arctic front will drop south through the region on Wednesday. A strong northwest flow will set up behind the front Wednesday night and Thursday. High pressure will build in from the west Thursday night and will crest over the region on Friday. High pressure will shift offshore Friday night and will hold there through Saturday. A warm front will approach from the south Saturday night and Sunday. && .NEAR TERM /UNTIL 6 AM TUESDAY MORNING/... Update...RAP H9 to H8 frontogenesis continues to best describe areal coverage of radar echoes at this hour. I have adjusted PoP to match that field. The RAP forecast is for that forcing to move very little N or S thru morning...but rather slide Ewd on a parallel line. So I have PoP increasing along that line and gradually increasing in area as low pressure develops. Otherwise no major changes. Previous discussion...Weak surface wave riding along stalled frontal boundary sitting offshore early this afternoon will continue east into the maritimes this evening. Lingering rain or snow showers in midcoast areas should be coming to an end by late afternoon. Precipitation ahead of the next wave already edging into the lower Hudson Valley and expect occasional light rain or snow showers to brush southern New Hampshire zones during the evening hours with little if any accumulation. Looking for steadier snow to shift into southern New Hampshire after midnight... overspreading the remainder of the forecast area after daybreak Tuesday. Have issued Winter Weather Advisories for southern New Hampshire for late tonight through Tuesday afternoon. Advisories in coastal and southern interior portions of Maine kick in around 10Z and go into the early evening. Generally looking for a 3 to 6 inch snowfall in these areas with the bulk of that during the daylight hours Tuesday. Some indications of a mix in the far south and coastal areas during the day Tuesday which may hold down amounts in those areas. Farther north...2 to 4 inches will likely cover the mountains and foothills. High temperatures will range from the mid 20s north to the mid 30s south. && .SHORT TERM /6 AM TUESDAY MORNING THROUGH TUESDAY NIGHT/... Update...Latest model guidance remains in excellent agreement on placement of H8 frontogenesis during the day Tue. With the expectation for the heaviest precip to fall just on the cool side of that forcing...that places Srn interior NH and coastal Wrn ME in the prime spot for a high end advisory snowfall. One thing I am keeping an eye on is the trend for models transitioning from an open wave at H8 to a closed low in the Gulf of ME. That is giving some signals for more concentrated band of snowfall across coastal Wrn ME during the afternoon Tue. This is most notable on the GFS...RGEM...and ECMWF solutions...and in good agreement with extended HRRR snowfall algorithms. Previous discussion...Have issued Winter Weather Advisories for southern New Hampshire for late tonight through Tuesday afternoon. Advisories in coastal and southern interior portions of Maine kick in around 10Z and go into the early evening. Generally looking for a 3 to 6 inch snowfall in these areas with the bulk of that during the daylight hours Tuesday. Some indications of a mix in the far south and coastal areas during the day Tuesday which may hold down amounts in those areas. Farther north...2 to 4 inches will likely cover the mountains and foothills. High temperatures will range from the mid 20s north to the mid 30s south. Low pressure will race east into the maritimes Tuesday night with snow ending in far eastern zones during the evening hours. Downsloping winds behind the low will bring partial clearing overnight. Lows will range from the mid teens north to the mid 20s south. && .LONG TERM /WEDNESDAY THROUGH MONDAY/... Arctic cold front comes crashing through the forecast area on Wednesday, particularly during the afternoon. This arctic front may herald in the coldest air mass we have seen on Thanksgiving on record. But first, the airmass along the front will be conducive to snow squalls. Given the current timing of the front, the most likely time frame for these will be during the afternoon hours and may cause brief locally dangerous driving conditions due to low vsbys in heavy snow along with quickly slickening road conditions. Not a good combination on the busiest travel day of the year. Not everyone will see one, but brief whiteout conditions are quite possible for those that do. In addition, a weak area of low pressure may accompany this front - likely moving across central or northern zones. There may be enough ascent with this feature to drop a couple inches of snow north of the low track. Have accounted for this possibility in our snowfall grids. Otherwise, the coldest air we have likely seen in any recorded November will arrive in the wake of the front. Highs will likely remain in the teens during the daylight hours on Thanksgiving day with wind chills around if not below zero the vast majority of the forecast area. High pressure crests over the region Friday into Saturday giving us warmer and less windy weather. Thereafter, several short wave troughs ejecting out of the central states may affect our region early next week. As of right now, these could be rain events after starting as a mix - both Saturday night/Sunday and again around Monday/Tuesday. However, solutions are likely to change going forward at this juncture. && .AVIATION /04Z TUESDAY THROUGH SATURDAY/... Short Term...MVFR/IFR ceilings this evening. IFR/LIFR ceilings/vsby developing after midnight and persisting through Tuesday. Becoming VFR Tuesday night with areas of MVFR ceilings in the north. Long Term...Local IFR conditions in snow showers and snow squalls Wednesday afternoon followed by VFR conditions (MVFR mountains) Thursday. Winds Wed night and Thu likely gust around 30 kt from the NW. VFR Friday and Saturday with lighter winds. && .MARINE... Short Term...Have issued SCA`s for the outer waters Tuesday. Long Term...A strong cold front will move across the forecast area Wed afternoon or early evening. Gales are possible if not likely in the wake of the front Wednesday night through Thursday. A gale watch has been posted. && .GYX WATCHES/WARNINGS/ADVISORIES... ME...Winter Weather Advisory from 5 AM to 7 PM EST Tuesday for MEZ018>028. NH...Winter Weather Advisory from 2 AM to 5 PM EST Tuesday for NHZ006>015. MARINE...Gale Watch from Wednesday afternoon through Thursday evening for ANZ150-152-154. Small Craft Advisory from 7 AM to 10 PM EST Tuesday for ANZ150- 152-154. && $$ NEAR TERM...Legro
Area Forecast Discussion
National Weather Service Lincoln IL
738 PM CST Mon Nov 19 2018 .UPDATE... Issued at 737 PM CST Mon Nov 19 2018 Cold front is showing up on radar from Jacksonville to Bloomington at 730 pm. Scattered sprinkles and flurries began to develop around sunset and have picked up on both sides of the front, so the forecast was recently updated to include a mention in areas north of I-70 this evening. Temperatures ahead of the front have not fallen off quite as fast as first thought, but overall low temperatures still look good. Updated grids/zones have been sent. && .SHORT TERM...(This evening through Tuesday) ISSUED AT 245 PM CST Mon Nov 19 2018 Weak cold front over far northwest Illinois will move across our area this evening bringing another band of cloudiness southeast into central Illinois. Short term models continue to suggest the better lift and moisture will be to our north and northeast tonight but the last few runs of the HRRR model indicated some isolated rain and snow showers possible over our far eastern counties this evening. Otherwise, dry weather is expected overnight as winds shift into the northwest bringing in another chilly air mass with temperatures to our northwest this afternoon having a tough time getting out of the middle 20s. We won`t see anything that cold but a definite chill will be in the air late tonight with lows dipping to near 20 north to the upper 20s south of I-70. High pressure will settle south into the Midwest on Tuesday with forecast soundings indicating a strengthening subsidence inversion which may effectively trap the low level moisture/clouds on Tuesday keeping the cloud cover across the area longer than currently forecast, especially over the east. Will go with a gradual decrease in cloud cover from northwest to southeast during the late morning and early afternoon hours, but confidence not that great on that happening based off some of the forecast soundings. Temperatures mostly in the 30s for daytime highs tomorrow. .LONG TERM...(Tuesday night through Monday) ISSUED AT 225 PM CST Mon Nov 19 2018 Chilly weather to hold across the forecast area into Wednesday morning before the pattern begins to shift over the lower 48 as the deep upper low across the upper Great Lakes shifts well off to our east, while an upper low settles across the southern Rockies. This should allow more of a west to southwest flow pattern to develop and bring warmer air into the Midwest for the second half of the work week. Temperatures by Wednesday and Thanksgiving day should moderate into the mid 40s to near 50 degrees with afternoon temperatures around 50 on Friday and the start of the weekend Saturday before we see a cool down starting Sunday. As the longwave trof repositions itself across the southern Rockies late in the, models depict several shortwaves ejecting across the Plains and into the Midwest bringing an increasing chance for rain in our area starting on Friday. Unfortunately, it appears we will have periodic chances for rain into the weekend and depending on the exact track of the second wave forecast to come out of the southern Plains later Sunday, there could be a rain/snow threat Sunday night into Monday, with any snow chance mainly across our far north based on the latest track of the surface low. && .AVIATION...(For the 00Z TAFS through 00Z Tuesday evening) Issued at 536 PM CST Mon Nov 19 2018 TAF sites have improved to VFR conditions early this evening, though there`s some concern that ceilings will regress as the low level inversion strengthens tonight. Have gone with MVFR conditions at most sites overnight, though KSPI is more on the fringe and went with a TEMPO period this evening, as a front passes. East central Illinois may take until early afternoon Tuesday to see a significant improvement. && .ILX WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...Geelhart SHORT TERM...Smith LONG TERM...Smith AVIATION...Geelhart
Area Forecast Discussion
National Weather Service Jacksonville FL
921 PM EST Mon Nov 19 2018 ...MILD LOW TEMPS AND AREAS OF FOG AGAIN TONIGHT... .UPDATE... Low stratus was settling to the surface as fog already this evening across SE GA as temps/Tds cool into the low/mid 50s under a surface ridge axis bringing calm winds. HRRR continued to resolve this scenario well with advection fog expanding SSW and filling in across SE GA through the early morning hours, with another dense fog advisory probable for at least SE GA and portions of NE FL near the I-10 corridor. A few hours before sunrise, HRRR trends suggested fog actually scouring out across our NW GA zones from Jesup toward Douglas as low level mixing increases ahead of weak surface front sliding south across GA overnight. Issued a Special Weather Statement (SPS) for all of SE GA and the I-10 corridor of NE FL to alert of fog development tonight, with periods of patchy dense expected (dense fog defined as visibility < 1/4 mile). Farther south across the remainder of NE FL, dew pt depressions were larger and the airmass was more mixed due to proximity of a weak surface trough across central FL. Through the night, expect more patchy intermittent radiation fog across our southern FL zones where SREF guidance indicated more passing low/mid clouds downstream of mid level short wave trough. CAM guidance indicate a few spotty showers possible after midnight moving across our NE FL zones associated with the mid level short wave trough and convergence near the lingering surface trough across central FL, and trended rain chances at 14% or less for areas along and south of St. Augustine to Ocala. Temperatures will trend a bit cooler than last night with low in the low/mid 50s inland (upper 40s in normally cooler locales) to near 60 toward the Atlantic coast. && .AVIATION... Restrictions to IFR or lower most probable at JAX, VQQ and CRG tonight, with MVFR conditions advertised after 08Z for SSI, SGJ and GNV. Low potential for passing sprinkle/light showers near GNV and SGJ early Tue morning, but probability too low to include in TAF at this time. Weak front will slide south of the area through Tuesday with prevailing VFR conditions by early afternoon and WNW winds 10 kts or less. && .MARINE... Light and variable winds over the waters for much of the evening as a weak high pressure ridge axis extends overhead. Winds will transition to more NNW after midnight with winds 10 kts or less. Combined seas 2-4 ft. A few spotty showers possible after midnight as a weak upper level disturbance moves over the area from the west. Rip Currents: Moderate NE FL Tue. Low risk SE GA Tue. && .HYDROLOGY... The Altamaha River at both Charlotteville and Baxley is forecast to rise into minor flood through mid-week. River flood warnings remain in effect. && .PRELIMINARY POINT TEMPS/POPS... AMG 52 71 41 64 / 10 10 0 0 SSI 58 71 48 65 / 10 10 0 0 JAX 56 73 47 68 / 10 10 0 0 SGJ 60 73 53 70 / 10 10 0 0 GNV 58 74 47 70 / 10 10 0 0 OCF 60 76 49 72 / 10 10 0 0 && .JAX WATCHES/WARNINGS/ADVISORIES... FL...None. GA...None. AM...None. && $$ Enyedi/Kennedy