Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 12/22/18

Area Forecast Discussion
National Weather Service La Crosse WI
524 PM CST Fri Dec 21 2018 .SHORT TERM...(This evening through Saturday) Issued at 254 PM CST Fri Dec 21 2018 Region remained under cyclonic flow per the latest water vapor satellite due to strong inversion and time of year...low stratus deck of clouds continue to rotate around upper level trough over the eastern United States...per latest visible satellite imagery. Main forecast concerns this evening and tonight if when low stratus deck of clouds erode across the forecast area. The 21.12z GFS/NAM/ECMWF and hi-resolution models are not handling the low level moisture trapped under strong inversion. This will have impacts on sky conditions clearing across the forecast area this evening. Surface ridge builds into Wisconsin tonight and eventually erodes the low stratus deck of clouds across the forecast area. Weak surface front/shortwave trough moves across the Northern Plains states and the Great Lakes Region Saturday. The 21.12z GFS/ECMWF/NAM show weak forcing and lift in association with the shortwave the bufkit soundings indicate saturation in low levels. With the weak lift and forcing...confidence not high enough on introducing any precipitation chances til late afternoon Saturday across northern portions of forecast area. .LONG TERM...(Saturday night through Friday) Issued at 254 PM CST Fri Dec 21 2018 Focus turns to Sunday into Monday...Upper level becomes west to east zonal flow across the northern tier United States. With pieces of energy embedded in the flow and cooler airmass advecting into the forecast area. There is potential for some light snow or flurries...mainly across the northern sections of the forecast area. At this time...have small chances of light snow over this area Sunday. Main forecast concerns Monday night through Friday is the storm system moving into the Northern Plains and the Great Lakes Region Wednesday into Thursday. Next impulse to impact the forecast area Monday night. The deterministic 21.12z GFS/ECMWF are placing impulse and lift/forcing slightly further south than previous runs...providing the best snow chances across parts of northeast Iowa and southwest Wisconsin. The deterministic 21.12z GFS/ECMWF/GEM models are in better agreement than the 21.00/06z runs in placement/movement of surface/upper level features Wednesday into Thursday. With slight differences in placement/movement...confidence in the forecast track of the system Wednesday into Friday remains low. The forecast area is expected to receive precipitation from the system Wednesday into Thursday...however details of any type of precipitation and amounts is still uncertain. Stay tuned to the latest forecast and trends with this system. && .AVIATION...(For the 00Z TAFS through 00Z Saturday evening) Issued at 524 PM CST Fri Dec 21 2018 A low confidence scenario with respect to cloud trends is expected into Saturday. A weak ridge of high pressure will spread over the area tonight. However, satellite and surface obs indicate quite a bit of stratus extending west into MN. With weak low-level flow and a stout inversion, confidence in improving conditions is low. Model guidance has been quite poor with cloud trends, but the RAP keeps IFR/MVFR ceilings tonight through Saturday as a weak low pressure system crosses the area. As a result, have trended towards a more pessimistic forecast but will amend if necessary should the stratus show signs of erosion overnight. Winds will remain light through the period. && .ARX WATCHES/WARNINGS/ADVISORIES... WI...None. MN...None. IA...None. && $$ SHORT TERM...DTJ LONG TERM...DTJ AVIATION...JM
National Weather Service Burlington VT
958 PM EST Fri Dec 21 2018 .SYNOPSIS... Strong low pressure will lift into Canada overnight while a surface cold front will sweep across the North Country on Saturday. Occasional showers will persist tonight, which combined with snow melt will cause some area rivers to reach minor flood stage. A mild night will turn sharply cold on Saturday with any leftover rain showers changing to snow showers. A dusting to an inch or two of snow accumulation is possible, especially over northern Adirondacks and the mountains of central and northern Vermont. Cooler weather with minor chances for light snow is expected for early this upcoming holiday week. && .NEAR TERM /UNTIL 11 AM SATURDAY MORNING/... As of 951 PM EST Friday...No real changes as everyting in quasi-stationary until surface low near KMSS lifts NNE overnight then a west to east slow progression. No changes to going forecast. Check hydro section for flood watch and river status. Previous Evening Discussion...Steadier rain/showers on our west and east ends of our forecast area, otherwise dry slot across region. Current forecast appears on track with eastern activity continuing to diminish but western activity will slowly progress east after surface low passes to our north and cold front moves east. Lack of gradient with moist atmosphere and cold ground has developed patchy/areas of fog and this should prevail overnight. Previous Afternoon Discussion...Flood watch continues until 1 PM Saturday for combination of rainfall and snow melt from eastern Dacks into all of VT. The near term focus continues to be hydro related and associated impacts from rainfall and snowmelt. Based on River Forecast Center still anticipating multiple rivers to reach minor flood stage with a few approaching moderate. Through early this aftn storm total rainfall has ranged from 0.60 to 1.50 across our fa which combined with snow melt has resulted in some rises on rivers. Expect peak flows overnight tonight into Saturday. Based on Emergency manager feedback and web cams, the threat for ice jam related flooding is minimal. Water vapor shows deep full latitude mid/upper level trof across the eastern Conus with strong sub-tropical moisture plume advecting into central/eastern New England. This axis of higher pws and deeper moisture is slowly shifting east of our fa, as mid/upper level dry slot moves across northern/central NY. This will impact our region overnight with steadier/heavier activity becoming more showery. Given embedded 5h vorts in the southerly flow aloft, along with axis of 850 to 500mb moisture over central/eastern VT, will continue to mention cat pops thru 03z...before dry slot arrives. Additional areas of showers will be possible throughout the night across our entire fa, but heaviest qpf will be focused over eastern sections. Expect areas of fog, especially over colder snowpack regions of eastern/central/northern Vt and parts of the dacks. Temps hold steady overnight mainly in the 40s to lower 50s, before dropping aft 06z across our western cwa/slv regions. Well defined commahead on water vapor will lift across our cwa btwn 09-15z Saturday with general redevelopment of precip from west to east. Have noted some lightning activity upstream and RAP soundings indicating showalter values of -1 at SLK with cape of 100 to 200 j/kg. Have not included thunder given low confidence, but cannot completely rule out a rumble or two over northern NY tonight with fropa. As the deeper mid/upper level moisture arrives, winds will be shifting to the southwest/west with strong 925mb to 850mb caa developing. This will cause 850mb temps to rapidly decrease with 0c line over the dacks by 12z Saturday and thru most of VT by 15z, with 925mb near 0c line over the CPV at this time. Expect a rapid change to snow showers across the summits of the dacks btwn 09z-12z and 12z- 15z across the central/northern Greens. A period of wet accumulating snowfall is likely with several inches possible above 2000 feet. A dusting to a quick inch or so is possible below 2000 feet. Snow showers quickly become trrn focused by 18z as drier develops on brisk northwest winds. Temps continue to fall throughout the aftn with readings in the 20s and 30s by evening. && .SHORT TERM /11 AM SATURDAY MORNING THROUGH MONDAY/... As of 237 PM EST Friday...Quiet weather expected Sunday through Sunday night with mountain snow showers winding down through the morning hours. Overall, no real accumulations expected. We`ll remain cloudy through most of the day, with a few flurries likely flying around near the high terrain. High temperatures will be near normal in the mid 20s to around 30 with lows only falling slightly into the upper teens to low 20s. Winds will decrease during the day Sunday as high pressure nudges in ahead of our next shortwave...this shortwave will determine whether areas of New England see a white Christmas or not. && .LONG TERM /MONDAY NIGHT THROUGH FRIDAY/... As of 237 PM EST Friday...Weak low pressure moving out of the Great Lakes on Sunday will track east out of Lake Ontario and east- southeast across southern New England. Compared to 00z/06z run of model guidance, this track is slightly further south. Tricky forecast for the northern portions of our CWA with Burlington area on outer fridges of available moisture. The best chances for eeking out a white Christmas will be across our central and southern zones. Overall, looking at slightly less than to around 1" of snow. Things trend quieter Monday night through late- week. Near normal temperatures are expected in the upper 20s to low 30s. A weak shortwave moves through Wednesday night but with hardly any available moisture, anticipate mainly increase in cloud cover and no real falling precipitation. Our attention shifts towards Friday when another mature system advances north out of the Central Plains. As previously mentioned, model spread with this system is large so plenty of time for things to change. && .AVIATION /03Z SATURDAY THROUGH WEDNESDAY/... Through 00Z Sunday...A mix of VFR to LIFR conditions is expected during fist half of the TAF period. Varying cloud cover across the CWA will lead to changing conditions with most TAF sites bouncing from VFR to LIFR as clouds move out and fog quickly forms. As clouds move back in conditions will improve to varying degrees. Showers will move back into KMSS after 04Z and progress westward into VT after 12Z which will keep conditions around MVFR and IFR though the end of the period. Expect winds to be light and variable under 10 knots overnight before becoming south to southwesterly at 10-15 knots with some gusts across the northern TAF sites of 20-25 knots. Outlook... Saturday Night: Mainly VFR, with local MVFR possible. Windy with gusts to 30 kt. Slight chance SHSN. Sunday: VFR. Slight chance SHSN. Sunday Night: Mainly VFR, with local MVFR possible. Chance SHSN. Monday: Mainly VFR, with local MVFR possible. Chance SHSN. Monday Night: VFR. Slight chance SHSN. Christmas Day: VFR. NO SIG WX. Tuesday Night: VFR. Slight chance SHSN. Wednesday: VFR. Slight chance SHSN. && .HYDROLOGY... As of 955 PM EST Friday...Flood watch remains in effect as we still have some rivers responding to earlier rainfall and continued snowmelt. We have received some reports of water over some roads for minor flooding but nothing significant. Pretty much behaving as earlier anticipated. There has been some ice that has affected gages but no reported jams as ice still young and not as thick as it could have been. && .CLIMATE... Below are record highs for today and tomorrow for selected sites. If highs for tomorrow are broken, they`ll likely occur in the pre-dawn hours. DateKBTV KMPV K1V4 KMSS KPBG KSLK 12-21 61|1957 56|1957 49|2012 62|1957 59|1957 55|1957 12-22 57|1990 58|1949 45|1998 63|1949 54|1967 55|1949 && .BTV WATCHES/WARNINGS/ADVISORIES... VT...Flood Watch through Saturday afternoon for VTZ001>012-016>019. NY...Flood Watch through Saturday afternoon for NYZ028-031-034-035. && $$ SYNOPSIS...Taber NEAR TERM...Taber/SLW SHORT TERM...LaRocca LONG TERM...LaRocca AVIATION...Verasamy HYDROLOGY...JMG/Neiles CLIMATE...JMG
Area Forecast Discussion
National Weather Service State College PA
1052 PM EST Fri Dec 21 2018 .SYNOPSIS... Low pressure will drag a cold front through from west to east early tonight, allowing colder air to move in. As rain ends this evening, it will turn to snow over the Alleghenies and Laurels. A weak Alberta Clipper will affect the region around Sunday night. High pressure should bring mainly fair weather for Christmas Day into the middle of the week. && .NEAR TERM /THROUGH SATURDAY/... Colder air reaching into the central mountains now with rain changing to snow in the higher elevations. Still a batch of moderate rainfall to cross my northeastern counties so will keep Flood Watch going there through midnight. Streams overall are lowering, but could rise again in these areas. Winter Weather Advisory remains in effect for Laurels and also McKean Co. The rain turning to snow on the western edge of the deformation band might yield an hour or two of 1"/hr rate snowfall in these loactions, and the Laurels will also have the typical upslope snow post-front later tonight and early Sat AM. Have gone with 2-4" in the Laurels but there could be spots on the ridges and west-facing slopes which get 6" or more by noon Sat. && .SHORT TERM /SATURDAY NIGHT THROUGH 6 PM SATURDAY/... Accumulating snowfall should be ending over the NW early in the day, but may linger into early aftn in the Laurels. Totals of 2-4 with higher amounts on the ridgetops. The winds will be gusty out of the WNW. Best gusts will be over the Laurels. The snow and ambient temps will not be conducive to generate blowing snow, though. Maxes will be limited by the good CAA. Will keep them in the 30s except in the lower Susq where they sould get into the L40s with a downslope flow and some sunshine. && .LONG TERM /SATURDAY NIGHT THROUGH FRIDAY/... Our best chance at a White Christmas appears to be linked to a fast moving low amplitude shortwave that will be moving through the region Sunday afternoon into the overnight. It will be pretty moisture starved and the models show the usual pattern of the precip favoring western higher elevations, and petering out rapidly as we move into central and especially eastern portions of the CWA. But a coating to an inch from central areas west would be welcome by most given the holiday timing, though travel issues will need to be monitored. Confidence at this point is low. Christmas Day looks chilly with temperatures generally in the 30s, but it should be dry with a mix of sun and clouds. There are differences that arise by the Wed-Thu timeframe with the ECMWF favoring continued mainly dry conditions, and the GFS showing a warm advection pattern developing with rain by Thursday. I used a model blend to bring in low chance POPs by the end of the extended. && .AVIATION /04Z SATURDAY THROUGH WEDNESDAY/... Low pressure will lift north of Pennsylvania this evening, as a trailing cold front works east across the region. Upsloping northwest flow will continue to produce ifr/lifr cigs across the high terrain of the Alleghenies this evening from KBFD south through KJST. In addition, expect rain to change to snow in this same area, resulting in reduced vsbys late evening through around midnight. Further east, expect predominantly mvfr conditions later this evening, as band of rain moves across the area. Expect diminishing precipitation and rising cigs late tonight, as drier air flows in behind the cold front. However, the entire area will experience increasingly gusty northwest winds overnight. Latest HRRR supports frequent gusts between 20-30kts late tonight, with the highest gusts across the southwest half of the state. Residual moisture ascending the Appalachians is likely to produce lingering mvfr stratocu Saturday from KBFD south through KJST. Further east, downsloping flow should yield predominantly vfr conditions. A tight pressure gradient behind departing storm system will result in gusty west-northwest winds throughout the day. Model soundings indicate frequent gusts of 25-30kts are likely with diminishing winds after sunset. .Outlook... Sun...AM low cigs possible NW Mtns. Evening light snow possible, mainly northern/western Pa. Mon...AM snow showers/vis reductions possible NW Mtns. Tue...Evening light snow possible, mainly W Mtns. Wed...No sig wx expected. && .CTP WATCHES/WARNINGS/ADVISORIES... Winter Weather Advisory until noon EST Saturday for PAZ005-024- 033. Flood Watch until 1 AM EST Saturday for PAZ037-041-042-046- 051>053-058. && $$ SYNOPSIS...Dangelo NEAR TERM...Dangelo/DeVoir SHORT TERM...Dangelo LONG TERM...La Corte AVIATION...Fitzgerald HYDROLOGY...
Area Forecast Discussion
National Weather Service Duluth MN
933 PM CST Fri Dec 21 2018 .UPDATE... Issued at 523 PM CST Fri Dec 21 2018 Updated for the 00z Aviation Discussion below. && .SHORT TERM...(This evening through Saturday night) Issued at 348 PM CST Fri Dec 21 2018 Skies have cleared this afternoon for portions of northern Minnesota while stubborn stratus has held on elsewhere. Winds over western Minnesota have turned southerly ahead of an approaching area of low pressure, which will affect the area tonight through Sunday. The initial shortwave trough will move into northern Minnesota tonight with precipitation moving into our western zones overnight. The shortwave will flatten the mid- level ridge by Saturday morning. A second lobe of vorticity will follow across the Northern Plains and into the Upper Midwest by Saturday afternoon. Light snow is expected from late tonight through Saturday night and into Sunday as the system stalls over the region. Look for a dusting up to half an inch of snow over our southern zones with 1 to 3 inches along the international border. Some locations along the north shore may pick up 4 inches with orographic enhancement on easterly winds. Temperatures tonight will dip into the middle single digits above zero over interior areas of the Minnesota Arrowhead and the low 20s in central Minnesota with upper teens and low 20s in northwest Wisconsin. Highs on Saturday will reach the low 20s in the northeastern Arrowhead and around 30 degrees in central Minnesota. Lows Saturday night will be in the upper teens and low 20s. .LONG TERM...(Sunday through Friday) Issued at 348 PM CST Fri Dec 21 2018 A slow moving area of weak low pressure will slide through the Northland to kick off the long term period. This will bring light snow and may even accumulate up to 2-4" in portions of the Northland - mainly near the Canadian Border. This should be a light and fluffy snow with low snowfall rates. There may be a period early Sunday morning for enhanced rates as the DGZ moves favorably overhead in conjunction with a relatively stronger omega nose, but still not strongly forced. After this system passes, another weak shortwave crosses on Christmas for some flurries over the Arrowhead. The main focus of the long term is the potential for a larger system on Thursday. With each consecutive run, I am more confident that the uncertainty with this system is and will remain high. While the majority of operational models move a surface low through Iowa and into Lake Michigan, there are a few things that catch the eye. A strong cold front fires off convection on the eastern side of this low and will act to deprive moisture from advecting far northward limiting its availability to create significant snowfall in the Northland. Models appear to ignore or highly downplay the sedimentation of the rich plume of moisture with this convection. A really strong system may overcome this, but we`re talking a filling 990mb low at worst with geostrophic forcing that is greatly reduced in this set of guidance. Further the GFS v3 actually fills the low as it approaches the area. One thing to watch for is the LLJ is quite strong (65 kt) with this system which may be enough to overcome the aforementioned deposition argument. Another interesting feature, is the system appears to generate a second cold front late Thursday over Illinois on the GFS v3 which would also act to slow down the snowfall rates and continue to sap moisture from the system. So, either way, the best course of action is to remain weather aware and plan for a strong system somewhere in the Midwest/Great Lakes area on Thursday as there are certainly indications that one of the strongest systems of the winter thus far may be on the horizon. && .AVIATION...(For the 00Z TAFS through 00Z Saturday evening) Issued at 542 PM CST Fri Dec 21 2018 Low stratus continues for portions of the region, particularly from KBRD east to KDLH and KHYR, stopping just south of KHIB. The ceilings will once again be the main concern for tonight. The models generally have been a bit too high on ceiling heights lately, so trended a bit lower than most of the guidance. The RAP model appears to be doing the best in handling the low-level moisture, which is indicating a more widespread moisture return, so expecting the stratus to expand overnight. Some high level cirrus clouds will continue to move eastward across the area ahead of a trough of low pressure that will move through the region tonight and Saturday, bringing our next chances of snow, with some light accumulations possible, especially over our northern areas. The snow with this system should be steady, but light in nature, through Saturday as the trough will be pretty slow moving. && .MARINE... Issued at 933 PM CST Fri Dec 21 2018 Weak high pressure will continue to shift eastward across western Lake Superior overnight, which will lead to light northeasterly winds. Despite the light winds, wave heights from Chequamegon Bay to Saxon Harbor in northern Wisconsin will continue to be in a Small Craft Advisory, with waves between 3 to 5 feet per the wave height model guidance. We did trim back the end time of the advisory to coincide with when the waves start to diminish overnight. As the high pressure ridge moves eastward, winds will shift from the east and southeasterly directions, which should lead to strengthening winds and building waves along the North Shore late Saturday morning into the afternoon. Another Small Craft Advisory may be needed, mainly from Silver Bay northeast to Grand Marais, but the pressure gradient appears to be a bit too weak to support advisory issuance at this time. && .PRELIMINARY POINT TEMPS/POPS... DLH 17 27 19 25 / 10 50 40 20 INL 10 26 20 24 / 40 80 80 30 BRD 15 31 19 25 / 40 40 10 20 HYR 18 29 20 29 / 10 40 40 20 ASX 20 30 22 31 / 10 30 40 30 && .DLH WATCHES/WARNINGS/ADVISORIES... WI...None. MN...None. LS...Small Craft Advisory until 4 AM CST Saturday for LSZ148. && $$ UPDATE...JTS SHORT TERM...Huyck LONG TERM...Wolfe AVIATION...JTS MARINE...JTS
Area Forecast Discussion
National Weather Service Lincoln IL
818 PM CST Fri Dec 21 2018 .UPDATE... Issued at 818 PM CST Fri Dec 21 2018 West edge of the low cloud deck has been making slow progress eastward, though several holes have recently developed in central and northwest Illinois. GOES-16 night fog imagery shows the stratus deck extending into South Dakota, though high clouds over Iowa are obscuring the amount of cloud breaks there. Latest HRRR ceiling guidance suggests any sort of wholesale clearing of the stratus will be well after midnight, though the cirrus won`t provide much of a clearing trend. Will have to watch the low temperatures, which may be a tad cool given the cloudier trend. In the meantime, updates have been sent for the cloud trends. && .SHORT TERM...(This evening through Saturday) ISSUED AT 215 PM CST Fri Dec 21 2018 Low clouds associated with the departing storm system off to our east continue to make slow progress east with most of the forecast soundings for tonight suggesting the clouds will gradually decrease from west to east. Coldest temperatures tonight will be where the sky remains clear the longest, across the west and northwest, while clearing not expected to take place until just before dawn over the far east, as a result, have nudged temperatures up a few degrees over far east central and southeast IL. Surface high pressure will shift east into our area on Saturday bringing a sun-cloud mixture along with above normal temperatures as we should see afternoon highs range from 40 to 45 degrees. .LONG TERM...(Saturday night through Friday) ISSUED AT 215 PM CST Fri Dec 21 2018 The surface ridge axis will shift east of the forecast area Saturday night allowing a return southerly flow to develop. With the south wind and a bit more clouds, early morning lows will not be as cold as tonight with most areas dropping into the upper 20s to lower 30s. Models indicate a weak shortwave will track across the region on Sunday dragging a weak cold front across the area during the day. Moisture profiles ahead of this system look meager at best, with some limited moisture noted on soundings as the upper wave and attendant frontal system shift just to our east later in the day. The upper wave and frontal system will shift off to our east by Sunday night into Monday with rather quiet weather expected thru Christmas Eve with afternoon temperatures on Monday mostly in the 40s. The next upper wave on Christmas Day is being handled a little differently than what we saw yesterday at this time with the better moisture and lift shifted further south near the Ohio River Valley. Mainly slight chance POPs during the day Christmas with low chance POPs holding into Christmas night, but confidence on the rain and snow Tuesday night rather low as the latest ECMWF taking the bulk of the moisture/precip chances off to our east by late Tuesday. The 12z ECMWF indicating upper level ridging building over the central U.S. in response to a deep trof tracking into the southern Rockies by Wednesday. Model consensus throwing POPs in every period starting Tuesday night but find that hard to believe, especially if the upper ridge is as strong as indicated on the 00z and 12z runs of the ECMWF which would suggest we would see a break in the rain/snow chances Tuesday night into Wednesday. The major storm system forecast to slowly eject out of the southwest late Wednesday into Thursday bringing our area the best chances for rain and mild temperatures. Based on the current low track, it appears a good part of our forecast area will see afternoon temperatures in the low to mid 50s on Thursday before the cold front sweeps across the area late Thursday/Thursday night, putting an end to the rain and cooling temperatures off for Friday, but still averaging above normal for late December. && .AVIATION...(For the 00Z TAFS through 00Z Saturday evening) Issued at 515 PM CST Fri Dec 21 2018 Expansive cloud deck around 1500 feet covers all of central Illinois at 23Z, but west edge is just west of the Mississippi River. AWIPS timing tool and models suggest ceilings should break out from KPIA-KSPI toward 06Z, KBMI-KDEC toward 08Z and KCMI by 10-11Z. Once this finally occurs, VFR conditions will prevail the remainder of the forecast period. Northwest winds will trend more southwest late tonight, as an area of high pressure drifts east out of central Illinois. && .ILX WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...Geelhart SHORT TERM...Smith LONG TERM...Smith AVIATION...Geelhart