Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 01/31/20

Area Forecast Discussion
National Weather Service Boston/Norton MA
1009 PM EST Thu Jan 30 2020 .SYNOPSIS... High pressure passes over our area tonight, then moves offshore during Friday. Temperatures moderate on Friday with dry conditions expected. Developing low pressure tracks well offshore Saturday. This system may bring light amounts of rain or snow to the region, with the best chance along the south coasts of Massachusetts and Rhode Island. Cool, blustery and mainly dry weather follows Sunday behind the departing ocean storm. High pressure off the southeast U.S coast provides dry mild weather Monday. An approaching cold front may bring a risk of showers and mild temperatures by Wednesday. Colder air and a mix of rain and snow showers will be in place for Thursday. && .NEAR TERM /UNTIL 6 AM FRIDAY MORNING/... 10 PM Update... Increased cloud cover across southern New England to account for the cirrus clouds moving through per observations. Have also bumped up low temperatures a few degrees to account for more cloud cover. Still monitoring the cloud cover across central PA and western NY. Have held off in bringing this in per the latest RAP guidance, but will need to keep an eye on it for Friday. 7 PM Update... High clouds will move over Southern New England during the night. Satellite imagery shows lower clouds now moving into Central PA, at a pace that would bring them into Southern New England starting around 7 AM. This will be monitored and may eventually lead to a cloudier forecast for Friday. But as for the overnight period the observations are in line with the forecast. No significant changes with this part of the forecast. Previous discussion... High pressure is centered over Southern New England, and slides offshore toward morning. A short wave moving over the region brings scattered high deck clouds, but mainly clear skies are expected for most of the night. The clouds may temper overnight lows somewhat. Thinking we will get close to lows from Thu morning, just a couple of degrees or so warmer. Thus forecast lows are in the teens and low 20s, except along the immediate shorelines of MA and RI, as well as the Cape and Islands, with lows in the 20s. && .SHORT TERM /6 AM FRIDAY MORNING THROUGH FRIDAY NIGHT/... Friday... Surface high moves further offshore while mid level ridging builds in for much of the day. Expecting mostly sunny skies for the morning, then during the afternoon increasing clouds from SW to NE as the ridge moves offshore and moisture increases. This is mainly mid and high level moisture. One caveat to watch during Friday is the southwest flow may result in a marine layer/low level moisture pooling under the inversion. Thus there is a chance for marine stratus tomorrow in southern RI east to the Cape and Islands. Otherwise a dry day with moderating temperatures. Highs in the upper 30s to low 40s across much of the region, some mid 40s are possible. Friday night... Increasing clouds during the evening as southern stream low pressure system emerges off the Carolina coastline. While mainly dry conditions are forecast, there is the potential for some light snow or light rain during the overnight. Have low chance pops for HFD-PVD and SE MA, with a dusting to a couple tenths of an inch of snowfall is possible. To the north have opted for slight chance pops with a dusting of snow possible. Overnight lows in the upper 20s to low 30s for most of the area. && .LONG TERM /SATURDAY THROUGH THURSDAY/... Big Picture... Northern and southern streams connect and disconnect during the period. Major features are a phased trough moving through the Eastern Seaboard over the weekend, then a Pacific NW trough digging over the West and then shifting east to the Plains midweek. Model upper contour fields show a period of cooling over the weekend but are otherwise milder than normal. Mass fields are in agreement through Monday, and show a general similarity even through next Thursday. Confidence is good through the time period. Daily Concerns... Saturday-Sunday... Upper trough sweeps east across the Eastern Seaboard with a firmly progressive axis. A 170-kt jet from the southern stream moves through the trough and generates a coastal low in the Eastern Gulf and Carolina coast. The progressive flow carries both features northeast on a path that remains outside the 40/70 benchmark. This keeps most of the storm`s lift offshore of Southern New England as it passes. This suggests most of the precipitation will be offshore with values light at most over land. The best chance will be south of the the MA Pike. Temperatures project an initial rain along the coast and a snow/rain mix inland. This changes to all rain by the afternoon. Precip Saturday tapers off Sunday morning. The upper trough moves overhead Sunday morning-midday and should maintain clouds through that time followed by drying in the afternoon. Temperatures in the mixed layer will be equiv to -8C to -10C, which suggests max sfc temps in the upper 30s and lower 40s. Sunday night through Thursday... Warm front lifts through New York and New England Sunday night bringing a period of clouds and showers, with the best chance of showers over northwest Mass. Strong west winds are indicated Sunday night and Monday with low level values reaching 30 kt and 850 mb values at 40-50 kt. Weather system passes north of New England Tuesday and slowly pulls a cold front south over Southern New England midweek. This will mean a period of showers during that time, with mild temperatures Tuesday/Wednesday. As winds shift out of the northwest Wednesday night, the air will cool sufficiently to change the rain to snow from northwest to southeast. Temperatures will be borderline Thursday, so look for rain showers southeast and snow showers northwest. Mixable temps aloft will be equiv to -8 to -10C aloft Sunday, then -4C to -6C Monday through Wednesday. Cooler air moves in Thursday, with equiv temps aloft at -9C to -12C. All of this translates to max sfc temps in the upper 30s and lower 40s Sunday, then upper 40s/lower 50s Monday through Wednesday, and mid 30s to lower 40s Thursday. && .AVIATION /03Z FRIDAY THROUGH TUESDAY/... Forecaster Confidence Levels... Low - less than 30 percent. Moderate - 30 to 60 percent. High - greater than 60 percent. Tonight... VFR with light and variable/calm winds becoming light SW. Satellite and observations show lower clouds over Central PA edging east, with cloud bases at 3500-4000 feet. These clouds are moving at a pace that would bring them to the CT Valley at or after 7 AM. Friday... Mainly VFR with SW winds 5-10 kt. There is a slight chance of BKN MVFR CIGs along south coastal MA/RI with the possibility of marine stratus. Friday night... VFR to MVFR CIGs developing, with light SW winds. Low chance/slight chance for light snow/rain. VSBYs could be reduced below 5 miles in SE MA/Cape/Islands and RI. KBOS Terminal...High confidence in TAF. Slight chance of a sea breeze during Fri afternoon. KBDL Terminal...High confidence in TAF. Outlook /Saturday through Tuesday/... Saturday: Mainly MVFR, with local IFR possible. Breezy. Slight chance RA, slight chance SN. Saturday Night: Mainly IFR, with local MVFR possible. Breezy. Slight chance SN. Sunday: Mainly VFR, with local IFR possible. Sunday Night: Mainly VFR, with local IFR possible. Breezy. Monday through Monday Night: VFR. Breezy. Tuesday: MVFR/IFR conditions possible. Slight chance SHRA, slight chance FZRA. && .MARINE... Tonight... Variable winds becoming light from the SW overnight as high pressure passes over the area. Seas on the outer waters 2 to 4 feet, diminishing to 1-2 feet. Friday... Tranquil day on the waters as high pressure gradually moves east of the waters. SW winds increasing to 10 to 15 kts, with seas 1 to 3 feet. Friday night... Remaining in between systems as a low pressure emerges of the coast of the Carolinas. SW winds 10 to 15 kts continue, with seas 1 to 3 feet. Outlook /Saturday through Tuesday/... Saturday: Winds less than 25 kt. Chance of rain. Saturday Night: Winds less than 25 kt. Local rough seas. Slight chance of rain, slight chance of snow. Local visibility 1 to 3 nm. Sunday: Winds less than 25 kt. Local rough seas. Sunday Night: Low risk for Small Craft Advisory winds with gusts up to 25 kt. Local rough seas. Monday: Moderate risk for Small Craft Advisory winds with gusts up to 30 kt. Local rough seas. Monday Night: Winds less than 25 kt. Seas locally approaching 5 ft. Tuesday: Winds less than 25 kt. && .BOX WATCHES/WARNINGS/ADVISORIES... CT...None. MA...None. RI...None. MARINE...None. && $$ SYNOPSIS...WTB/NMB NEAR TERM...WTB/BL SHORT TERM...NMB LONG TERM...WTB AVIATION...WTB/BL MARINE...WTB/BL
National Weather Service Hastings NE
633 PM CST Thu Jan 30 2020 ...Aviation Update... .SHORT TERM...(This evening through Friday) Issued at 330 PM CST Thu Jan 30 2020 Satellite imagery shows stratus continuing to slowly erode from west to east across the area. Areas west of Highway 281 will end up seeing a nice bit of sunshine late this afternoon, but those closer to Highway 81 will likely see stratus linger straight into the evening and overnight. Tonight, a quick-moving shortwave and associated cold front will move from northwest to southeast across the area. A mix of light rain or snow is possible as this moves through, but most of the local area will only see sprinkles/flurries. Stratus will also expand westward again tonight, but fog isn`t expected to impact as much of the area as the previous couple nights. This is largely due the increasing northwest wind behind the cold front. That being said, the HRRR and RAP show some reduced visibility, mainly over northeastern portions of the area. On Friday, some sprinkles/flurries may linger into the morning, but should come to an end between 15-18Z as the upper level trough axis moves through. Temperatures are expected to range from the mid 30s in the east to the mid 40s in western portions of the area that will see more sun. This is pretty similar to today`s temperatures, but northwest wind gusts to around 25 MPH will make it feel a bit chillier. .LONG TERM...(Saturday through Thursday) Issued at 330 PM CST Thu Jan 30 2020 We will kick off February with a very warm weekend thanks to broad ridging at the mid and upper levels. On Saturday, westerly, downsloping winds should push highs into the 50s and 60s...a solid 20 degrees above our climatological normals. Sunday should be even warmer than Saturday. 850mb temperatures are forecast to be in the 17-19C range, likely translating to surface temperatures in the 60s for most. In fact, the EPS mean is in the 60-65 degree range for the entire area. The one issue is that the GFS continues to be faster with the next front, which leads to noticably cooler temperatures in northern portions of the area. Because of this uncertainty, our current forecast keeps some mid 50s in our north and east, but this could very well end up being too conservative. Long story short, it is going to be an unseasonably mild day, so get outside and enjoy it! The pattern flips back to cold on Monday as an advancing upper level trough pushes a cold front through the area. Highs on Monday may struggle to reach freezing...easily 20-25 degrees colder than Sunday. Both the GFS ands Euro then show this aforementioned trough become more positively tilted and slide through the area Monday night into Tuesday. This doesn`t look like a significant winter storm, but a few inches of snow are possible in portions of the area. Obviously, there is still plenty of uncertainty on amounts and location, so make sure to check back over the weekend or early next week. It will remain relatively cold through the middle of next week, but we may see a bit of a "warmup" back into the low 40s late in the week into the following weekend. Of course this will depend on the presence/lack of any snow cover. Beyond that, it appears that we will see a colder-than-normal pattern persist through at least the middle of February. && .AVIATION...(For the 00Z KGRI/KEAR TAFS through 00Z Friday) Issued at 631 PM CST Thu Jan 30 2020 General overview: Yet another fairly complex/low-moderate confidence TAF, especially with regard to ceiling height. From a very general perspective, we anticipate both KGRI/KEAR to spend the majority of the period under an MVFR ceiling, although at least starting out this evening KGRI is currently IFR and KEAR is VFR, so there is quite a disparity between these two (relatively) nearby terminals. Visibility-wise, KEAR should remain VFR throughout, but KGRI could see at least occasional MVFR these first several hours. Winds are actually fairly straightforward/similar for both sites, with initially southerly breezes this evening soon turning westerly and eventually more northwesterly behind a passing cold front. In fact, the majority of the period will feature WNW breezes sustained 10-15KT with some slightly higher gusts possible. Precipitation-wise, while nothing measurable is expected, both sites (but probably slightly favoring KGRI versus KEAR) could see passing sprinkles/flurries at almost any point through late Friday morning. Read on for a few more ceiling-related details if interested... Ceiling details (low-moderate confidence): As mentioned above, right out of the gate this evening we have quite a disparity between KGRI (IFR) and KEAR (VFR). While confidence in exact timing leaves a lot to be desired, the general expectation is that both sites will trend toward a middle-ground of MVFR later this evening/overnight, as ceilings rise a bit at KGRI and an MVFR deck eventually arrives/settles in from the north-northwest into KEAR. That being said, especially at KEAR, this lower cloud deck could also end up prevailing as low-end VFR instead of MVFR, it`s just a tough call at this point. About the only thing that currently carries halfway-decent confidence is that both sites should become prevailing VFR by sometime Friday afternoon. && .GID WATCHES/WARNINGS/ADVISORIES... NE...NONE. KS...NONE. && $$ SHORT TERM...Mangels LONG TERM...Mangels AVIATION...Pfannkuch
Area Forecast Discussion
National Weather Service Hanford CA
426 PM PST Thu Jan 30 2020 .UPDATE...Updated air quality issues section. && .SYNOPSIS... Eastern Pacific ridging pattern continues for the next few days keeping the forecast dry and warmer than average. A disturbance is forecast to bring light precip to the forecast area on Sunday, before another period of dry weather next week. && .DISCUSSION... GOES-17 visible satellite imagery shows high clouds moving southward across the forecast with a ridge of high pressure off to our west. As high pressure influences our weather today, afternoon highs will be several degrees warmer than yesterday, with afternoon highs in the 60-63 degree range across the San Joaquin Valley. 18z HRRR run is not showing much in the way of fog, but areas that get some clearing overnight could see some localized fog tomorrow morning. Heading into tomorrow, 500 mb heights continue to rise over Central California. Warming trend will continue tomorrow as a result, and highs are expected to be in the mid 60s across the valley, and near 70 in the Mojave Desert. As the ridge nudges east Friday night into Saturday morning, skies could be mostly clear, which may lead to fog formation across the valley. The dry pattern continues on Saturday, and depending on how much cloud cover there is during peak heating, it could be the warmest day of the week. The pattern changes on Sunday when an Inside Slider trough impacts the forecast area. Blended model guidance is forecasting light precip totals in the mountainous areas of the forecast area with this system through Monday morning. Accompanying the trough will be tightening gradients, leading to gusty winds across the Kern County Mountain passes and desert. A cooler airmass will be in place for the early portion of next week, with the main impact likely being the chilly morning lows on Tuesday and Wednesday morning. By midweek next week, another EPAC ridging pattern is being forecast by most global models, continuing the dry weather pattern. && .AVIATION... IFR and local LIFR visibility and ceilings in mist and fog 10z through 17z Friday in the San Joaquin Valley. Otherwise, VFR conditions will prevail for the next 24 hours. && .AIR QUALITY ISSUES... On Friday January 31 2020... Fireplace/Wood Stove Burning Status is: No Burning Unless Registered in Fresno... Kern... Kings... Madera and Tulare Counties. Further information is available at && .CERTAINTY... The level of certainty for days 1 and 2 is high. The level of certainty for days 3 through 7 is medium. Certainty levels include low...medium...and high. Please visit for additional information an/or to provide feedback. && .HNX WATCHES/WARNINGS/ADVISORIES... None. && $$ public/aviation/fw...Bollenbacher PIO/IDSS.............DH
Area Forecast Discussion
National Weather Service Lincoln IL
843 PM CST Thu Jan 30 2020 .SYNOPSIS... Issued at 209 PM CST Thu Jan 30 2020 Cloudy conditions will persist across the region to close out the week. There is a chance of light snow tonight, particularly south of a Jacksonville to Bloomington line. Accumulations will be very light, only a dusting in some locations. Temperatures will fall into the mid 20s to lower 30s across central Illinois. On Friday, temperatures will warm into the upper 30s to lower 40s. && .UPDATE... Issued at 843 PM CST Thu Jan 30 2020 Short-wave trough currently over eastern Kansas will eventually tap into limited deep-layer moisture to bring a period of light precip to central/southeast Illinois overnight into Friday morning. Upstream radar imagery and surface observations show light snow developing across western/southern Missouri. This precip will spread northeastward into the KILX CWA mainly after midnight, with the most widespread precip confined to locations along/south of I-70. Latest HRRR suggests it will be slow to arrive and may not fully develop until closer to dawn. Precip type will initially be a drizzle/flurry mix, but will quickly change to light snow as the seeder-feeder mechanism provides ice crystals to the low-level moist layer. Overnight snow amounts will be quite light...amounting to only a couple tenths of an inch at most. && .SHORT TERM...(This evening through Friday) ISSUED AT 209 PM CST Thu Jan 30 2020 Surface ridge of high pressure over the Midwest this afternoon will drift east towards the East Coast tonight allowing southwest flow to spread back across the Mississippi Valley. The combination of modest low/mid level warm air advection and falling heights from approaching upper low digging across the Upper Midwest will result in modest synoptic scale ascent across the region this evening and overnight. Low level moisture remains locked in place across the region, and deeper moisture is progged to arrive as southwest flow returns. This should allow for some precip in at least portions of central Illinois overnight. May initially see drizzle or patchy freezing drizzle near the onset of precip this evening before the deeper moisture allows for ice nuclei to be introduced into the column resulting in snow. While there remains some uncertainty in how widespread snow will be overnight, some very light accumulations of a dusting to a few tenths are possible by daybreak Friday, particularly south of a Jacksonville to Bloomington line. A lead shortwave trough ejecting from the base of the main upper trough will shift east of the local area early on Friday and should provide a window of subsidence and dry weather through the day Friday. Temperatures will warm into the upper 30s to lower 40s under continued cloud cover. The main upper trough is then progged to move across the region Friday evening and overnight with the chance for light precip returning, primarily snow, particularly along and north of the I- 72/Danville corridor. Coming off relatively mild daytime temps and maintaining surface temps near freezing Friday night, and overall light intensity expected, the chance for accumulating snow seems fairly low, perhaps a dusting on grassy surfaces. .LONG TERM...(Friday night through Thursday) ISSUED AT 209 PM CST Thu Jan 30 2020 Upper low will pass east of the region early on Saturday with strong subsidence overspreading central Illinois in its wake. This will shut down precip chances through the weekend, though cloud cover will likely remain trapped under a strong inversion on Saturday. By Sunday though, continued subsidence should help erode stratus from above as the inversion heights lower, while mixing in the boundary layer with increasing southwest winds should help scour out remaining low level moisture. Outside of some passing high clouds then, this should set the stage for the return of sunshine to the area. Very warm temps aloft of 15-16C at 900mb are progged to overspread the local area resulting a very steep inversion. Temperatures will be a bit tricky as a result as very modest changes in the depth of the mixing will result in several degrees difference at the surface. IF (and only IF) clouds clear as expected, we should easily be looking at a top 5-10 warmest day on record if not near record highs for February 2nd. The uncertainty in the cloud forecast adds a considerable bust factor to temps on Sunday. Guidance ranges between 40s on the cold end from the NAM to 60s from the ECMWF with majority of models clustering in the lower to mid 50s. Meanwhile on Sunday, low pressure will be moving east across Ontario with a trailing cold front sagging south across the Upper Midwest and stalling over central Illinois on Monday. Farther west, a strong trough is progged to dig across the western CONUS, lifting northeast across the Great Plains on Tuesday. Low pressure will form over the plains as a result with precip chances returning along the stalled frontal boundary and ahead of the approaching upper trough later Monday through the middle of the week. Expect sharp temperature contrast across the aforementioned front, possibly around 30 degrees of difference between the northwest and southeast counties of the forecast area. Placement of the boundary will be key to temps at any given location, so don`t be surprised to see changes in the forecast for your area if the placement of the expected frontal position shifts in the coming days. Precip chances should end with some snow midweek as the low departs towards the east coast. Dry but more seasonable conditions look likely for the latter half of next week. && .AVIATION...(For the 00Z TAFS through 00Z Friday evening) Issued at 538 PM CST Thu Jan 30 2020 Ceilings have risen to VFR at all terminals except KBMI late this afternoon. While FEW-SCT lower clouds will be present, it appears VFR conditions will persist for a few hours before gradually lowering to MVFR by around midnight. As an upper disturbance approaches from the southwest, all models suggest a further lowering to IFR at KSPI by 09z...then further northeast to KBMI/KCMI by around 11z. In addition, areas of fog will develop, reducing visbys to 2-3 miles late tonight into Friday morning. The fog will be slow to dissipate, with visby restrictions likely lingering until early afternoon. Winds will remain light/variable through the entire 00z TAF period. && .ILX WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...Barnes SYNOPSIS...Deubelbeiss SHORT TERM...Deubelbeiss LONG TERM...Deubelbeiss AVIATION...Barnes
Area Forecast Discussion
National Weather Service Northern Indiana
605 PM EST Thu Jan 30 2020 .SYNOPSIS... Issued at 218 PM EST Thu Jan 30 2020 Dry but cloudy conditions will persist this afternoon. There could be a few flurries coming off Lake Michigan this evening. There is a chance for snow Friday morning but little to no accumulation is expected. Another chance for rain or snow will arrive Saturday morning but dry, sunny, and warm conditions are anticipated for Sunday. A more significant weather system is possible middle of next week. && .SHORT TERM...(This Evening through Friday) Issued at 218 PM EST Thu Jan 30 2020 Upper ridging and surface high pressure across the area this afternoon have allowed for mostly dry conditions. However, there does continue to be some low-level moisture trapped under the inversion, which is responsible for the persistent cloud cover. Added a slight chance of snow showers along Lake Michigan and to the southwest for late this afternoon and evening in coordination with NWS LOT. The HRRR is showing some lake-enhanced convergence in conjunction with a weak mid-level shortwave, but confidence is low given drier air at the surface and aloft. Moisture is expected to increase overnight though as a trough moves in from the west. This will bring a decent chance of snow through Friday morning across the area, but accumulations will be light at less than an inch. Decent b boundary layer mixing can also be expected with this system, which will allow afternoon temperatures to rise into the mid to upper 30s, thus melting most of any snow that does accumulate. && .LONG TERM...(Friday Night through Thursday) Issued at 218 PM EST Thu Jan 30 2020 A somewhat stronger shortwave will move into the region by Saturday morning, with another chance of a wintry mix and snow, but accumulations will again be minimal. Latest model runs have cut back on QPF with better energy both north and south in a slightly split synoptic scale flow pattern. Dry high pressure will then build over the center of the country on Sunday and temperatures will warm well above normal, with highs both Sunday and Monday around 50 degrees. Rain is expected to begin Monday night in association with a warm front. The cold front will move south of the area Tuesday, and temperatures will cool some, but precipitation should remain mostly rain through the day. Much colder air will advect in on Tuesday night and Wednesday, thus the rain will change to snow. At this time it is too soon to give specific accumulation amounts due to storm track uncertainties, but several inches of snow may be possible. Drier conditions should follow for Thursday. && .AVIATION...(For the 00Z TAFS through 00Z Friday Evening) Issued at 605 PM EST Thu Jan 30 2020 Persistent overcast will continue through this TAF cycle. Ceilings to begin at low end VFR this evening then drop down to MVFR Friday morning as weak system moves through the region. Model blend does have brief window of IFR cigs and MVFR visibilities mid-day Friday but given very weak signal among the ensemble members for any measurable precip to accompany this system prefer to stick with MVFR ceilings for now. Winds expected to remain light and variable through the period. && .IWX WATCHES/WARNINGS/ADVISORIES... IN...NONE. MI...NONE. OH...NONE. LM...NONE. && $$ SYNOPSIS...Cobb SHORT TERM...Cobb LONG TERM...Cobb AVIATION...JAL Visit us at Follow us on Facebook...Twitter...and YouTube at:
Area Forecast Discussion
National Weather Service Chicago/Romeoville, IL
849 PM CST Thu Jan 30 2020 .UPDATE... 849 PM CST Evening Update... Have updated forecast to include a mention of flurries and patchy light freezing drizzle this evening, mainly from the Chicago metro area west. Not expecting impact from freezing drizzle, given its patchy/very light nature and expected short duration. Also increased pops for light snow overnight, mainly in the I-80 to I-88 corridor regions of northern IL. No changes to minor accumulations, with generally less than a half inch expected. After a quiet late afternoon/early evening, regional radar mosaic is indicating some very light precipitation moving across north central IL at mid-evening. Surface reports indicate this is a mix of some very light snow/flurries and some very light freezing drizzle. DVN`s 00Z sounding indicates the top of the low level stratus layer is in the -10C range, which should support ice crystal nucleation and snow flakes, though surface obs indicate otherwise. Mid-level saturation, seen at/above 600 mb in DVN`s sounding, is expected to lower overnight however, which is expected to provide ice crystals/flakes in a seeder-feeder process which should turn precip over to all light snow in time. IL doesn`t have much roadway surface temp data available, though current road temps just west of the Mississippi River in eastern IA are in the 32-34 range, and with slightly higher air temps farther east this is likely an indication that any patchy light freezing drizzle should have little if any road impacts. Farther to the west, radar returns across parts of central and southeast IA are what is expected to expand eastward across northern IL and northwest IN after midnight tonight, and produce a period of light snow. This is in association with the northeastern periphery of a short wave tracking across Missouri and central IL. Weak but persistent warm advection, and isentropic upglide, with a slight enhancement to modest H8 southwesterly winds, appears to peak during the midnight-sunrise period. Model guidance continues to indicate a couple of hundredths of QPF which would translate to some minor accums of less than half an inch by the time things taper off to flurries around sunrise Friday morning. 4 km WRF simulated reflectivity, and to a similar but lesser extent the RAP and HRRR, appear to focus the I-80 and I-88 corridor regions across northern IL for perhaps the better accumulation potential, and have boosted pops across these areas into the likely category. Forcing weakens shortly after sunrise, though low level stratus may continue to produce flurries during the day, as broad upper trough remains across the region above our persistent low level stratus. Ratzer && .SHORT TERM... 219 PM CST Through Friday... Our stagnant weather pattern continues today, with widespread cloud cover locked in underneath a stout subsidence inversion above 6 kft. For the rest of the afternoon, not expecting much change from what you see outside as a result. Some hints remain in the guidance that a subtle increase in low-level convergence immediately near the lake may help to squeeze out a few snow showers late this afternoon and into the early evening hours, but these look to be of relatively minimal consequence given the marginal degree of low-level saturation. The main feature of interest that we`re monitoring is an upstream shortwave trough which is pinwheeling eastward across the Northern Great Plains early this afternoon. Within this broad cyclonic mid- level flow are several subtle disturbances which will be slowly translating overhead through at least the next 36 to 48 hours or so. The first disturbance looks to bring a period of lightly accumulating snowfall to the region later tonight and into Friday morning. This wave can be seen in recent moisture-channel imagery across northwestern Iowa. Recent mesoanalysis reveals a fairly steep mid-level lapse rate plume is in place out that way, not surprising given the convective look to recent satellite images. The core of this steeper lapse rate environment does look to remain mainly south and west of our region through tonight, but always is a little worrying to see pockets of 8+ C/km lapse rates lurking nearby. Overall guidance is in pretty good agreement depicting light precipitation overspreading most of the region around and just after midnight as the core of mainly modest forcing for ascent moves in. Most of this lift can be seen on the 285 K theta surface tonight with the main area of ever-so-slightly more enhanced upglide developing near and north of the I-80 corridor. Guidance today has trended towards perhaps a bit more in the way of QPF for the overnight/Friday morning period as a result, and have gently nudged snowfall amounts up just a bit to near a half inch in isolated spots. There is some potential that at the front end of precip there`s a brief lack of cloud ice for heterogeneous nucleation with a lingering dry wedge in the 5-10 kft layer limiting the potential for seeder-feeder mechanisms to help things out in that department. Low-level cloud top temperatures do look to remain in the -9 to -10 C range, so do not have any freezing drizzle mentioned at this time, but is something we`ll be keeping an eye on. Either way, as the mid-levels continue to saturate, it does look like we`d be able to quickly inject additional ice crystals from above into the lower stratus deck, turning any spotty drizzle over to light snow. Interestingly, some of the recent hi-res guidance is spitting out pockets of several hundredths of an inch of liquid-equivalent QPF through Friday morning, which could support some isolated snowfall amounts headed towards one inch. Most of this activity looks to end through the mid-morning hours on Friday although, as has been case recently, we won`t have any mechanisms to really scour out the low-level moisture. As a result, flurries or even some lingering light snow will remain possible into the afternoon hours, mainly for locales east and south of I-55 where we`ll likely hold onto a sliver of low-level instability. Carlaw && .LONG TERM... Friday night through Thursday... 200 PM...Forecast concerns remain light snow potential Friday night...warm-up Sunday/Monday and then a possible winter storm for Monday night through Tuesday night. The last of this week`s series of weak waves will move across the area Friday night and overall...models have weakened some with this system. There is still a potential for a light dusting of snow but temperatures will likely be in the lower there may not be much impact. This activity will quickly end from west to east overnight and Saturday morning is now looking mainly dry. precip ends there may be one last chance for drizzle or freezing drizzle where temps remain below freezing. Models then quickly transition to significant warming Saturday night into Monday with some bust potential...especially over the deeper snowpack across the northwest cwa which may mute the warming some. It does appear that Sunday will see sunshine... perhaps some higher clouds by afternoon. Assuming sunshine does occur...high temps Sunday appear in-line with mex/ecm mos guidance...40s over northwest IL...lower/mid 50s elsewhere. High temps on Monday have always been tricky based on when a cold front moves across the area. While this front may not be all that will likely mean the difference of several degrees. The gfs/gem are still showing a shift to northeast across much of northern IL by Monday morning with the ecmwf now showing a faster shift to northeast on Monday. Temps likely could still be well into the 40s with 50s possible across the far south but there still remains some uncertainty for high temps Monday. Ecmwf has been overall rather consistent with its solution over the past few days for the possible storm system Monday night through Tuesday night next week. Only notable change this afternoon is precip duration now stretches into Wednesday morning. The same trend of rain mixing/changing to snow is on track with the potential for a wintry mix somewhere in the middle. While it remains too early for details...the general track of the system has remained similar and would lay out a band of snow of at least a few inches across mainly the northern half of the cwa. As the winds turn northeast...they steadily increase Monday night into Tuesday as the gradient tightens. Still several days away but this time period would also need to be monitored for possible lakeshore flood concerns. cms && .CLIMATE... Here are the record highs Sunday into Monday. Sunday`s record high temp for Chicago looks to be most vulnerable and is the lowest record high temp for the month of February. Sun Feb 2 Mon Feb 3 Mon Feb 3 Record High Record Warm Low Record High Chicago 51 (1992) 39 (2019) 59 (1992) Rockford 52 (1987) 37 (2019) 54 (1992) - Izzi && .HYDROLOGY... 355 AM CST Much of the Rock River basin is running at greater than 90% of normal streamflow for late January and the Fox river is running close to 90% of normal. NOAA`s National Operational Hydrologic Remote Sensing Center is estimating 1 to 2 inches of water locked up in the snow pack over north central IL east into the upper Fox River watershed. If current forecasts for record/near record warmth verify, then rapid snowmelt would take place Sunday and especially into Monday as dewpoints potentially rise into the 40s. At this point, no significant rain is forecast Sunday or Monday, but with the Rock and Fox Rivers running so high, rapid snowmelt could result in significant rises on the Kishwaukee, Pecatonica, Rock, and Fox Rivers. - Izzi && .AVIATION... For the 00Z TAFs... 615 PM CST The main concerns include: * Periodic light snow or snow showers late tonight through about mid day Friday * CIGs likely deteriorating to IFR from west to east late tonight into Friday morning * Reduced VSBY in -SN/-SHSN and BR, with temporary IFR VSBY likely...can`t rule out LIFR VSBY in -SN and FG * Another period of -SN or -SHSN possible Friday evening Another weather disturbance will move over the area late tonight through Friday morning. This will likely bring with it periods of light snow or snow showers. Accumulations of a coating to a few tenths of an inch are possible. CIGs are currently MVFR to lower VFR and will gradually build down from west to east. As the initial wave of -SN occurs late tonight, it appears RFD has best chance for temporary IFR CIGs and then should go prevailing IFR by about 12z. Farther east including ORD and MDW, confidence is lower in IFR CIGs initially but then is high enough for TEMPO IFR mention during the morning rush. Increasing low level moisture along with the periods of -SN/-SHSN will likely result in BR. In the TAFs, have prevailing MVFR VSBY and TEMPO IFR, with adjustments likely needed as trends become more clear. MAVMOS and especially GFSLAMP text guidance hitting the lower VSBY harder Friday morning, with 1/2SM to 1SM VSBY. This seems to be a lower probability scenario, but will certainly need to monitor trends. The initial disturbance will exit east Friday afternoon, with another disturbance dropping southeast out of Wisconsin Friday evening and night. Flurries will be possible through Friday afternoon and light snow possible Friday evening, but for now with confidence low, went with a dry TAF Friday afternoon and onward. Winds will be light through the period and not expected to impact operations, with a general southerly direction becoming more southwesterly Friday PM. Castro && .LOT WATCHES/WARNINGS/ADVISORIES... IL...None. IN...None. LM...None. && $$ Visit us at Follow us on Facebook, Twitter, and YouTube at:
Area Forecast Discussion
National Weather Service Marquette MI
642 PM EST Thu Jan 30 2020 .SHORT TERM...(This evening through Friday) Issued at 407 PM EST THU JAN 30 2020 WV imagery and RAP analysis indicated a split flow pattern with mainly weak mid/upper level features affecting the Upper Mississippi Valley and northern Great Lakes. A mid/upper level low was located over northwest MN with weak shortwaves ahead of this features supporting area of light snow or flurries over wrn WI. Otherwise, persistent clouds prevailed with above average temps in the mid 20s to around 30. Tonight, expect generally quiet conditions with the potential for some light snow or flurries developing into portions of central Upper Michigan late tonight as the weak MN shrtwv edges through the area. Forecast soundings suggest that the moisture depth, or relatively small dry layer, will be sufficient for ice nuclei to support mainly snow rather than fzdz. Friday, as the shrtwv moves through, expect the limited -sn chances to diminish by afternoon. Otherwise, even with the persistent clouds, weak WAA will help temps climb into the lower 30s. .LONG TERM...(Friday night through Thursday) Issued at 336 PM EST THU JAN 30 2020 Weak shortwave moving through Friday night may spark some light snow showers or yet even more freezing drizzle, especially as this weak system lacks any substantial moisture. As ridging sets up over the Plains later in the day on Saturday, expect any precip chances to exit off toward the east. However, the Upper Great Lakes will remain on the periphery of this ridge that will be shifting into the GoMex later in the weekend, allowing for precip chances to remain non-zero through Sunday morning. Should be dry though later in the day. The remainder of the long-term period doesn`t currently appear to bring any appreciable precip chances to Upper Michigan, with just sporadic, lower-end chances early next week. Above normal temps will dominate this weekend through Monday before an Arctic airmass ushers colder temps back in on Tuesday. The warmest day of the period looks to occur on Sunday (40s!), dropping off to 15 to 20 degrees cooler on Tuesday (for high temps). Lows of course will respond accordingly, with single digits perhaps making a return Tuesday night into Wednesday morning. && .AVIATION...(For the 00Z TAFS through 00Z Friday evening) Issued at 642 PM EST THU JAN 30 2020 Persistent low-level moisture will result in prevailing MVFR cigs at KIWD/KCMX/KSAW thru this fcst period. However, MVFR cigs have recently cleared out at KIWD, and it may not be until late tonight that MVFR cigs return. Winds at all terminals will remain light thru the period. && .MARINE...(For the 4 PM Lake Superior forecast issuance) Issued at 407 PM EST THU JAN 30 2020 Light winds, generally 20 kts or less, are expected across the lake through Saturday. Look for 25-30 kt winds spreading west to east across the lake Sunday morning (with an isolated gale force gust possible between the Keweenaw and Isle Royale) then veering NW and remaining near 25 kts on Monday behind a weak cold front. && .MQT WATCHES/WARNINGS/ADVISORIES... Upper Michigan... None. Lake Superior... None. Lake Michigan... None. && $$ SHORT TERM...JLB LONG TERM...lg AVIATION...Rolfson MARINE...JLB
Area Forecast Discussion
National Weather Service Shreveport LA
1005 PM CST Thu Jan 30 2020 .SHORT TERM.../Tonight/ The evening water vapor imagery indicates an upper trough extending south across the Cntrl and Srn Plains of SW TX from a closed low center over WCntrl MN, with enough mid and upper level forcing ahead of the trough resulting in areas of -RA and embedded -SHRA over portions of E TX/SW AR/N LA. These areas of RA will continue to spread E across the remainder of the region overnight, and will result in light QPF amounts generally near or less than a tenth of an inch. Did increase pops to high and mid chance over areas E of the trough, while lowering/dropping pops farther to the W over SE OK/adjacent SW AR and extreme NE TX. The GFS and HRRR also depict cigs lowering overnight as well, possibly as a result of patchy FG/-DZ development late in wake of the departing trough, mainly over portions of extreme NE TX/SE OK/SW AR, and thus have maintained mention in the forecast. Did bump up min temps a degree or so tonight, given the lack of cold advection, with 03Z temps/dewpoints running a degree or so higher than the NBM/MOS. Zone update already out...grids will be available shortly. 15 && .PREV DISCUSSION... /issued 543 PM CST Thu Jan 30 2020/ AVIATION... A mix of IFR and low MVFR cigs will become IFR/LIFR later this evening through the overnight hours, as patchy areas of -RA begin to spread ENE across much of the region. Some vsby reductions will be possible, although more reduced vsbys may occur between 09-15Z Friday across portions of SW AR/NW LA/adjacent sections of E TX. However, cigs should begin to slowly improve by late morning through the afternoon from W to E, although cigs will remain MVFR for the remainder of the TAF period through at least Friday night. Light NNE winds tonight will become NW around 5kts after 15Z. /15/ && .PRELIMINARY POINT TEMPS/POPS... SHV 43 55 38 60 / 50 10 0 0 MLU 44 54 39 58 / 40 10 0 0 DEQ 40 53 34 58 / 10 10 0 0 TXK 40 52 37 58 / 40 10 0 0 ELD 39 54 37 58 / 40 10 0 0 TYR 42 54 35 61 / 30 10 0 0 GGG 43 55 36 61 / 50 10 0 0 LFK 45 56 39 62 / 40 10 0 0 && .SHV WATCHES/WARNINGS/ADVISORIES... AR...None. LA...None. OK...None. TX...None. && $$ 15