Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 12/28/24


AREA FORECAST DISCUSSION
National Weather Service Albany NY
944 PM EST Fri Dec 27 2024 .SYNOPSIS... An approaching warm front will bring some intermittent periods of light freezing rain and plain rain late tonight into Saturday afternoon as temperatures slowly rise to or above freezing. Milder weather returns Sunday and Monday as another storm system brings a widespread rainfall, which may result in localized poor drainage flooding. Confidence is increasing for another system to bring a mix of rain and snow around New Year`s Day. && .NEAR TERM /THROUGH SATURDAY/... Key Message: - A weak warm front will bring intermittent periods of freezing rain overnight into Saturday which could lead to locally slippery travel. Discussion: UPDATE as of 943 pm EST... Mid and high clouds continue to increase ahead of a weak thermal trough, as high pressure slowly drifts east from southern Quebec to northern Maine. We continued to increase the clouds prior to the light pcpn onset. Temps have not dropped off as much with the cloud cover, as the NYS Mesonet and western New England obs are mainly in the upper teens and 20s. Some mid and upper 30s are over the eastern Catskills (Tannersville 38F) and Taconics (Copake 36F). We tried to bring in the light freezing rain for the eastern Catskills, mid Hudson Valley, southern Taconics, and southwest New England between 1 am and 4 am, as the weak isentropic lift increases. The 00Z 3-km HRRR is more aggressive than the 00Z 3-km NAMnest with the onset and coverage. However, the spotty freezing rain and plain rain should be more widespread from the Mohawk River Valley, Capital Region and Berkshires southward between 3 am and 7 am. The Winter Weather Advisory looks good. Lows will generally be in the upper teens to upper 20s (a few warmer readings over the higher terrain) and then slightly rise toward daybreak. PREV DISCUSSION [0339 pm EST]... Intermittent periods of rain and freezing rain will begin before daybreak, mainly for areas south of Albany, before lifting northward during Saturday morning. Much of the precipitation departs the region by later Saturday afternoon. Overall QPF amounts do not look particularly high (generally up to one tenth of an inch for most areas except up to 0.25 inches across the mid- Hudson Valley into the Litchfield Hills). This will limit ice accumulation to up to one tenth of an inch with most areas just receiving a very light glaze. Still, the very cold ground surfaces can allow rain to freeze on any untreated or elevated surfaces. Even once air temperatures rise above freezing (33 or 34 degrees), rain can continue to freeze on surfaces until ground temperatures warm enough to prevent any additional icing. Will continue with the Winter Weather Advisory for all of eastern New York and western New England given the spotty nature of ice accumulation and potential impacts. While temperatures in most areas will rise into the upper 30s to mid-40s by Saturday afternoon, some sheltered areas in the Mohawk Valley into the Upper Hudson region may still be around freezing into Saturday evening. As a result, the Winter Weather Advisory for the Mohawk Valley was extended until 5 PM Saturday. Patchy fog will likely develop by Saturday afternoon as milder air moves over the very cold ground and snowpack. && .SHORT TERM /SATURDAY NIGHT THROUGH MONDAY/... Key Message: - A soaking rainfall is expected Sunday into Monday which will lead to river rises and the potential for some localized flooding. There remains a marginal risk for excessive rainfall during this time. Discussion: A break in the precipitation will occur Saturday night for most areas, though some patchy fog and even drizzle may occur through the night. Temperatures Saturday night will hold fairly steady in the 30s with some localized areas within the Lake George/Saratoga region possibly hovering right around freezing. The next negatively-tilted upper shortwave and surface low pressure system arrives on Sunday, continuing into Monday. Surface temperatures will continue to warm into the 40s and 50s allowing for this system to bring all rainfall. One round of rainfall will occur on Sunday lifting from south to north along another warm front. The second round of precipitation then moves through Sunday night into Monday morning along the cold front. Periods of moderate to locally heavy rainfall will be possible Sunday night into Monday morning. Overall QPF amounts of 0.75 to 1.50 inches are expected across the region with some locally higher amounts across the eastern Catskills due to upslope enhancement. The milder conditions, rain and snowmelt will result in river rises and may result in localized flooding (see Hydrology section for details). Rain is expected to linger into early Monday before the cold front passes allowing rain to transition to scattered showers. Cooler air advances in by Monday afternoon leading to falling temperatures. This may allow for some snowflakes to mix in across the Adirondacks. && .LONG TERM /MONDAY NIGHT THROUGH FRIDAY/... Key Messages: - Mild conditions on Tuesday followed by a trend towards more wintry weather. - A storm system looks to bring snow to at least the higher terrain Wednesday, followed by additional lake effect snow showers Thursday and Friday. Discussion: A weak ridge of high pressure will bring fair and mild weather on Tuesday. The next system is expected to impact the region for Tuesday night into Wednesday. Initially, this will be another milder system heading into the area from the west, but the deepening upper wave generates its own cold air and temperatures cool gradually aloft as the surface wave deepens along the New England coast. Probabilistic guidance shows the best chance for any accumulating snow would be across the southern Adirondacks and southern Green Mountains. As the system departs, colder air will work its way into the region on northwest winds. Some lake effect snow showers should start to develop in the storm`s wake for Wednesday night into Thursday, especially for western and northern areas. It will become breezy Thursday and Friday behind the deepening low over eastern Canada, and with temperatures near normal to slightly below, it looks blustery and cold. Lake effect snow showers are expected to continue Thursday and Friday over western areas. && .AVIATION /03Z SATURDAY THROUGH WEDNESDAY/... High pressure will move eastward from southern Quebec over northern New England. A weak disturbance and a warm front will increase clouds early tonight with clouds thickening and lowering. VFR conditions will diminish after 06Z/SAT with some light freezing rain breaking out from south to north across the terminal sites. PROB30 or TEMPO groups were used to bring the light freezing rain initially at KPOU 06Z-09Z/SAT, 09Z-12Z/SAT at KALB/KPSF...and 11Z-15Z/SAT for KGFL. The intermittent light freezing rain will gradually transition to plain rain about 12Z/SAT, KALB/KPSF 16Z/SAT and KGFL 19Z/SAT. KGFL may remain light freezing rain before it diminishes in the early pm. The pcpn will be light and spotty, as temps gradually rise above freezing. Cigs/Vsbys will lower to MVFR levels 09Z-13Z/SAT and will continue to lower to IFR levels in the late morning/early afternoon. Widespread low MVFR/IFR cigs will continue in the afternoon with spotty drizzle. Vsbys will hover in the MVFR range. The winds will calm or light and variable direction at 4 KT or less tonight. They will light from the south/southeast mainly at 5 KT or less, except at KALB they may increase to the 10 KT by the late morning/early pm. LLWS was added to KPOU/KPSF after 12Z/SAT as the the 2 kft AGL winds increase to 30-35 KT with the sfc winds generally 5 KT or less. The LLWS should diminish towards nightfall. Outlook... Saturday Night: No Operational Impact. Patchy FG. Sunday: High Operational Impact. Definite RA. Sunday Night: High Operational Impact. Breezy. Definite RA. Monday: High Operational Impact. Definite SHRA...RA. Monday Night: No Operational Impact. NO SIG WX. Tuesday: No Operational Impact. NO SIG WX. Tuesday Night: High Operational Impact. Definite SHRA. New Years Day: High Operational Impact. Definite SHRA. && .HYDROLOGY... A period of moderate to locally heavy rain is expected Sunday into Monday morning. With a frozen ground in place in many areas, along with some snowmelt, runoff will be enhanced and might lead to some localized flooding. River rises are expected but no flooding is expected at this time. While ice has developed on area rivers, the overall depth is limited to mainly 3 to 6 inches (estimated). This shallow depth should limit the potential for ice jam development but could occur in any areas where obstructions block the flow of ice. Trends will continue to be monitored for any possible localized flooding or ice jams. && .ALY WATCHES/WARNINGS/ADVISORIES... CT...Winter Weather Advisory from 1 AM to 1 PM EST Saturday for CTZ001-013. NY...Winter Weather Advisory from 1 AM to 1 PM EST Saturday for NYZ047-051>054-058>061-063>066. Winter Weather Advisory from 5 AM to 5 PM EST Saturday for NYZ032-033-038>043-048>050-082>084. MA...Winter Weather Advisory from 1 AM to 1 PM EST Saturday for MAZ001-025. VT...Winter Weather Advisory from 5 AM to 5 PM EST Saturday for VTZ013>015. && $$ SYNOPSIS...Rathbun/Wasula NEAR TERM...Rathbun/Wasula SHORT TERM...Rathbun LONG TERM...SND AVIATION...Wasula HYDROLOGY...KL/Rathbun
Area Forecast Discussion
National Weather Service La Crosse WI
526 PM CST Fri Dec 27 2024 .KEY MESSAGES... - Widespread rainfall continues moving northward this afternoon into Saturday. Storm total amounts of 3/4" to 1" are expected. - Above normal temperatures tonight into Monday with highs in the 40s and lows in the 30s. Record warm low temperatures at Rochester and La Crosse are possible tonight. - Precipitation chances continue Monday afternoon into Tuesday with more seasonable temperatures by the middle of next week. Lesser chances for precipitation on Sunday. && .DISCUSSION... Issued at 243 PM CST Fri Dec 27 2024 Widespread Rainfall This Afternoon Into Saturday After fighting with some drier low to mid level air over much of the area earlier today, northward moisture advection associated with a 500hPa and associated surface wave has sufficiently saturated the column across northeast Iowa this afternoon, allowing rainfall to begin. The moisture advection and subsequent rainfall will continue northward through the evening and into Saturday as the wave propagates northward through the area. Various bits of 900-600hPa frontogenesis move through the area this evening as seen in the RAP which combined with lift from the low should provide enough upward motion for some moderate rainfall rates across the area. The 27.12z HREF currently paints 40-80% probabilities for rates above 0.1 inch per hour but these probabilities fall off dramatically at and above 0.15 inches per hour, down to 0-20%. With PWATs still in the 99th percentile or above as compared to climatology, widespread QPF values of 3/4" to 1" continue to be expected. With the higher rainfall amounts and ever eroding snowpack, the concern for ice jams continues into Saturday for local rivers with the runoff, especially those further north. Will continue to monitor for impacts that develop, if any. Models continue introducing below freezing temperatures above 1.5kft north of I-94 Saturday morning as the low moves northward and exits the region, suggesting some snowflakes could mix in with the rain across these areas. This is dependent on how low the freezing level is able to get, but 27.12z HREF soundings show minimal spread amongst the members in the temperature profile and indicate good agreement that the freezing level should be 1.5kft or less. Still not expecting any snow accumulations if any snow does fall given warm surface temperatures. Above Normal Temperatures Tonight Into Monday Continue to expect above normal temperatures tonight into the weekend. Overnight lows are expected to be in the mid to upper 30s, 25-30F above climatology for this time of year. These current forecast lows remain at or above the current record warm low temperature for both La Crosse and Rochester. Dry air an subsidence moving into the region on the backside of our passing wave should allow for some clearing of our recently very cloudy skies Saturday afternoon, especially west of the Mississippi River. Depending on how much skies are able to clear, could see some additional warming Saturday afternoon. Have trended high temperatures towards the 75th percentile of the NBM for Saturday afternoon to account for the expected clearing, resulting in high temperatures into the mid 40s. Precipitation Chances Monday Afternoon into Tuesday and Lesser Chances Sunday Clouds look to fill back in as we head into Sunday as a 500hPa trough and associated surface wave move northeastward out of Texas. These features look to mainly stay to our south and east, but could still see a glancing blow of rain in far southwest Wisconsin. There has also been some indication in the deterministic models and the GEFS that rain could develop in our far west Sunday afternoon as well as this system moves through the area (0%-15%) associated with isentropic ascent on the 290-300K surface and weak frontogenesis at 925hPa during this time period. However, have tended towards a drier solution at this time due to poor agreement amongst various model solutions and an overall lack of indication in ensemble guidance. The NBM continues pulling the low pressure system expected to develop across the Great Plains Monday further south run to run. However, looking at the 27.00z LREF members, there is still plenty of discrepancy regarding location of the highest precipitation chances. In the NBM, precipitation chances remain 30-50% south of I-90, which has been a consistent signal over the last several days, suggesting that we should see some sort of precipitation, but how much precipitation our area sees will depend on if the NBM continues to take a more southerly track similar to the GEFS/GEPS (lower precipitation chances: 20-40%) or a more northerly track similar to the ENS (higher precipitation chances: 40-60%). Regarding precipitation type, it continues to look as though precipitation will initially fall as rain before northwest winds begin to usher cold air into the column, allowing for a transition to a rain/snow mix before ultimately transitioning to all snow on the backside of the low. Temperatures become more seasonable by mid next week owing to the cold air advection behind the low with highs in the 20s. && .AVIATION /00Z TAFS THROUGH 00Z SATURDAY/... Issued at 526 PM CST Fri Dec 27 2024 Widespread rain continues through the overnight. Areas of fog will be possible overnight as visibilities are expected to range from 0.5SM to 3SM. CIGS will also remain low with cloud bases ranging from 200ft to 1000ft. Precipitation is expected to leave the area by mid-morning Saturday. There is a low chance (20 to 40%) of some snow mixing in with the rain in north central Wisconsin Saturday morning. Even with the precipitation ending, there will be enough low-level moisture around that the lowered CIGS and visibilities could hang around into the early afternoon. By mid-afternoon, trends are pointing towards a break in the thick cloud cover before returning Saturday evening. && .ARX WATCHES/WARNINGS/ADVISORIES... WI...None. MN...None. IA...None. && $$ DISCUSSION...Falkinham AVIATION...Cecava
Area Forecast Discussion
National Weather Service Sioux Falls SD
447 PM CST Fri Dec 27 2024 .KEY MESSAGES... - Fog continues to linger into the evening east of I-29. However, concern for fog expansion after sunset continues to grow. Additional dense fog may be possible with new advisories needed. - Well above normal temperatures expected Saturday and Sunday. Highs in the 40s both days. - Very light precip may fall Sunday morning east of I-29. Any impacts would remain minimal, but precipitation chances may increase in the future. - Impactful storm still on track for Monday into Monday night. Probabilities of >0.25" of QPF continue to trend towards 100%. Uncertainty on rain to snow transition is impacting overall snow potential but plan on light snow accumulations. Best advice is to prepare for some impact despite uncertainty. - High confidence in a downward temperature trend through the rest of the week. Below zero temperature probabilities grow to 20-30% by the end of next week. && .DISCUSSION... Issued at 225 PM CST Fri Dec 27 2024 THIS AFTERNOON: Fog and stratus continues to linger in areas of the higher elevations in Minnesota and Iowa. Further west however, with the arrival of a warmer southwest wind, highs have surged deep into the 40s. Anticipating some continued improvement in visibilities this afternoon, but if we can`t clear out fog/stratus by sunset, it won`t take long to settled back downward. TONIGHT: Winds should settle quickly after sunset allowing potential for lingering low stratus to again settled downward. In addition, if we can clear some of the high level stratus, then additional radiation fog may develop along the I-29 corridor later this evening. NBM visibility probs are once again too low given the setup, with HREF probabilities of less than 0.5" exceeding 80% again over NW Iowa into SW Minnesota into Saturday morning. Would like to see if cirrus can clear to aid in radiational cooling potential before issuing a dense fog advisory, but one is certainly possible. SATURDAY: With an increase in westerly wind Saturday, we may be able to scour out fog a bit faster than on Friday. Looking aloft, we`re continuing to see increasing low-lvl warm advection sliding through the Plains, pushing 850mb temperatures into the +6C range by Saturday morning. If we`re not dealing with lingering low clouds, then see now reason why temperature won`t again surge into the upper 40s to 50. Have followed the warmer RAP for temperatures tomorrow which sit around the 90th percentile of the NBM, but notably is still not the warmest guidance available. SUNDAY: Mid-lvl troughing, and left exit of an upper jet, moves through Saturday night into Sunday from west to east. While soundings show decent lift within a deep saturated layer above 700 mb, they also show a fairly stout dry layer below 700 mb. The NAM, perhaps with its boundary layer moisture bias, suggests QPF reaching the ground by daybreak Sunday along and east of I-29. If this seeder-feeder process can`t come to fruition, then precipitation would have a deep dry layer to make it through. Nevertheless, PoPs may need to be increased in the future. Temperatures on Sunday again climb into the 40s in most areas. MONDAY: The most impactful weather of the next week will take place on Monday. A fairly progressive mid-lvl trough drops from the Northern Rockies and into the Plains by daybreak. Moderate to strong gradually sloped mid-lvl frontogenesis will develop ahead of this wave. Soundings continue to show potential that most of the initial precipitation will occur as liquid with wet-bulb temperatures below 1200 ft still above freezing and surface temps near 32-37F. If overnight lows can drop a bit further into the 20s, then some very light icing could take place during the initial developing stages of precipitation prior to daybreak. However, wherever the initial band does form, precipitation rates have the potential to overwhelm this warm layer and you could begin to see a transition to snow at slightly warmer surface temperatures. Eventually the frontal forcing weakens by early afternoon Monday, replaced with a compact deformation zone that slides through the Missouri River Valley into the evening and overnight hours. Ensembles continue to show high probabilities (80%+) of 0.10"-0.25" of QPF with this system, with most of the variation in location due to positioning of the initial frontal band. The one thing that is a bit more apparent today is the slightly southward shift in the ECE as compared to the CME/GEFS. All-in- all, if rain can turn to snow in a more efficient manner, then general potential for a fairly large area of 1-3" of snow seems reasonable, with some potential for upwards of 4-5" in south central SD by time snow ends late Monday evening. TUESDAY-FRIDAY: Medium range models continue to come into good agreement that we`ll see a high amplitude ridge form over the Rockies by the middle to end of next week. This sharp north to northwestward turn in low-lvl flow will bring colder Canadian air southward, resulting in the drop of temperatures below normal for the first couple weeks of January. In fact, probabilities for low temperatures falling near or below 0 rise towards the 20-30% range by next Friday. && .AVIATION /00Z TAFS THROUGH 00Z SUNDAY/... Issued at 445 PM CST Fri Dec 27 2024 Winds will be light overnight, and fog is again to expand across areas from the Interstate 29 corridor and eastward during the night, and some of this fog may be dense. To the west of this area, fog will still be possible, though probabilities are lower. Fog is then expected to slowly dissipate by late Saturday morning. && .FSD WATCHES/WARNINGS/ADVISORIES... SD...None. MN...None. IA...None. NE...None. && $$ DISCUSSION...Dux AVIATION...JM
Area Forecast Discussion
National Weather Service Memphis TN
555 PM CST Fri Dec 27 2024 ...New AVIATION... .SYNOPSIS... Issued at 246 PM CST Fri Dec 27 2024 A dry and warm day is in store to kick off the weekend. Strong to severe thunderstorms are possible Saturday afternoon into the evening hours. As this system exits, a dry start to the work week before yet another system brings a cool down to the area late week. && .DISCUSSION... (This evening through next Thursday) Issued at 246 PM CST Fri Dec 27 2024 Shortwave ridging across the region has allowed mostly dry conditions across the area today. A dry slot depicted on satellite has allowed for some sunshine to poke through and allowed for temperatures to hang steady in the upper 50s and lower 60s. Confidence continues to increase for severe weather potential as a negatively tilted trough crosses the area on Saturday. Long term guidance hinted earlier at a weak perturbation ahead of the system bringing stratiform rain to the area, which would decrease the severe weather threat. Unfortunately, short term guidance is not showing much in the way. The severe weather threat remains conditional as instability is still the limiting factor. The LLJ will rapidly amplify mid-level flow which will provide plentiful bulk shear (50-60 kts) across the area, which also increases storm relative helicity. The amount of instability will come down to where the warm sector resides and if any cloud breaks allow sunshine to poke through. Several CAMS show a swath of CAPE between 500-700 J/kg from Clarksdale, Oxford, Tupelo and southward towards central Mississippi. Model soundings do still show a weak cap in the very early morning hours, but is quickly overturned as the warm sector and Gulf moisture approach the area. From the NBM, probabilities for SBCAPE exceeding 500 J/kg are less than 50%. The system now looks to approach from the MS Delta in the late morning into early afternoon and exit the CWA before midnight. Damaging winds and a few tornadoes are the primary concern, with heavy rainfall and large hail also possible. While the severe weather chances still remain favorable but awaiting limiting factor results, precipitable water values remain in the 90th percentile for this time of year (around 1.25"). The Mississippi Delta region received almost 2" of rain with rainfall from last night, with another 1-2" expected with this robust convection. Training of storms is also likely bringing rainfall totals to 1-3" along and south of I-40 with lesser amounts to the north. Be cautious of any elevated streams, rivers, and any urban areas that pond water easily. On the bright side, after the system exits east late tomorrow night, a brief lull in precipitation will arrive with moderate temperatures. The warmer temperatures will continue, but a disturbance on track to middle TN could bring a stray shower Monday night. A deep Pacific trough will move across the region on Tuesday. This cold front will bring much cooler (with morning lows near freezing) and seasonable weather. DNM && .AVIATION... (00Z TAFS) Issued at 555 PM CST Fri Dec 27 2024 Messy TAFs remain this issuance. Confidence in fog potential continues to grow across all TAF sites along a decent inversion amongst already saturated soils from this morning`s rainfall. HRRR is pretty aggressive with how low visibilities fall, though this solution can not be ruled out. Ceilings lower to IFR conditions around 06Z across the airspace, lowering to LIFR conditions by 09Z. By daybreak, ceilings briefly improve to MVFR conditions as wind speed increase to around 6-8 kts. A cold front will bring increased shower and thunderstorm activity tomorrow afternoon and into evening impacting each terminal with its movement. LLWS is expected to impact MEM beginning around 02Z tomorrow with the movement of a quick moving jet. AEH && .MEG WATCHES/WARNINGS/ADVISORIES... AR...None. MO...None. MS...None. TN...None. && $$ PUBLIC FORECAST...DNM AVIATION...AEH
Area Forecast Discussion
National Weather Service Melbourne FL
701 PM EST Fri Dec 27 2024 ...New KEY MESSAGES, UPDATE, AVIATION... .KEY MESSAGES... Issued at 701 PM EST Fri Dec 27 2024 - There is a limited risk for excessive rainfall along the immediate Treasure Coast this evening. Patchy fog is possible overnight, especially north of Orlando. - Seasonably warm with scattered showers again on Saturday. Showers likely with isolated lightning storms Sunday afternoon into early Monday, ahead of a weakening cold front . - Poor to hazardous boating conditions continue through the weekend. - Mostly dry and pleasant for New Year`s Eve. Turning cooler to start the new year. && .UPDATE... Issued at 701 PM EST Fri Dec 27 2024 Rich subtropical moisture remains overhead this evening. Satellite-estimated PW values exceed 1.5", which lies between the 90th percentile and max moving climatological average. Combined with the onshore flow and a pesky inverted trough, we have seen training areas of moderate to heavy rain on the immediate Treasure Coast this evening. This has prompted a Flood Advisory near Stuart where localized 3" tallies have been reported along with some standing water. Hi-res guidance is not handling this all that well, with the HRRR likely performing the best. It indicates a lessening trend with this rain later tonight as slightly drier air briefly advects onshore. However, another surge of moisture may work northward from SoFlo toward daybreak, reintroducing showers to our Treasure Coast communities. This is a low confidence forecast, but one with potential impacts as reasonable worst-case rainfall off today`s HREF members exceed 4-6" over our southern communities through Saturday evening. Most areas will receive far less than this, but it underscores a localized threat for excessive rainfall. Elsewhere tonight, expect lighter showers to lessen in coverage with mostly cloudy skies. One area where skies may clear, or stratus lowers toward the surface, would be west of I-4 where we have added the mention for patchy fog overnight. With all this moisture in place, temps won`t fall too much, mainly into the mid 60s. && .PREVIOUS DISCUSSION... Issued at 300 PM EST Fri Dec 27 2024 Now-Tonight...18z RAP analysis indicates a weakened surface trough extending from east-central Florida northward to just off of the Carolina coast. Clouds have thinned enough to let some sunshine through this afternoon, with temperatures responding by climbing into the 70s in most spots. The cooler exception is the immediate Volusia coast where temps remain in the upper 60s. Isolated to scattered showers continue along the coast, and some additional development is now ongoing across inland Indian River, St. Lucie, and Martin counties. The general trend will be for decreasing rain chances overnight but still kept a 15-20 percent chance along the coast as showers offshore move northwestward. Lows fall into the 60s early Saturday morning, staying a few degrees warmer along the marine-land interface. Saturday-Sunday...Hi-res models indicate locally higher precip accumulation potential along the Treasure Coast Saturday morning, up to 0.75", with low-level flow favorable for repeated rains over the same locations. Forcing looks to be more modest on Saturday, but continued isolated to scattered showers are forecast to stream onshore from time to time. Afternoon temperatures peak a degree or so higher Saturday as a little less cloud cover is forecast. By Sunday, a cold front is forecast to approach the Florida panhandle as moisture increases out ahead of it. Surface winds increase out of the south 10-15 mph with gusts up to 20 mph. With daytime heating, the environment will become supportive of scattered showers and at least marginally supportive of isolated lightning storms. Modeled lapse rates are meager, so maintaining any storm`s strength may be a challenge. The best chance at a stronger storm will be near Lake George and northward, otherwise outside of our forecast area. Monday-Thursday (modified previous)...Behind Sunday`s front, zonal flow aloft sets up, keeping conditions relatively mild locally. Rain chances are forecast to remain below 20 percent across the peninsula from early next week into the middle of next week, with isolated shower development across the local Atlantic waters possible. Another front (or two) moves toward the peninsula around New Year`s Day, though current guidance is hinting that it will pass with very little fanfare as a result of limited moisture availability. The early week frontal passage will do little to help with temperatures, with highs remaining in the 70s Monday and in the upper 70s to low 80s on Tuesday. Lows generally in the mid 50s to low 60s. The second frontal passage, however, looks as though it could cool east central Florida off more significantly, with highs on Wednesday in the 70s and falling into the mid 60s to low 70s on Thursday. Lows are forecast to fall into the upper 40s to mid 50s Wednesday night, with the coolest night during the forecast period on Thursday, with lows in the 40s across all of east central Florida. && .MARINE... Issued at 300 PM EST Fri Dec 27 2024 Recent observations this afternoon from Buoy 41009 indicate waves around 6 to 7 feet with light and variable winds. A Small Craft Advisory remains in effect for the offshore Volusia and Brevard waters, where seas of 5 to 7 feet are expected through this evening. Elsewhere, small craft should exercise caution. Scattered showers, some heavy at times, are forecast to continue. Southeast winds Saturday veer southerly on Sunday ahead of an approaching, weakening cold front. After a brief period of light and variable wind on Monday, a southwest breeze of 10 to 15 knots returns on Tuesday ahead of a stronger set of reinforcing cold fronts mid week. && .AVIATION... (00Z TAFs) Issued at 701 PM EST Fri Dec 27 2024 Isolated to scattered showers are ongoing across portions of east central Florida this evening. Prevailing SHRA at FPR/SUA with TEMPOs through 03Z for VIS reductions in heavy downpours. Otherwise, VCSH mentioned at coastal terminals. There is potential for stratus to build again tonight. Models have significantly backed off on CIG reductions since the 18Z TAF package. Have raised CIGs slightly across the northern terminals overnight, but have opted to keep at least MVFR CIGs for these terminals based on previous nights trends. East-southeast winds 3-5 kts overnight, remaining slightly higher along the Treasure Coast. Winds increase to around 10-12 kts by late morning and into tomorrow afternoon with gusts up to 22 kts along the coast. && .PRELIMINARY POINT TEMPS/POPS... DAB 64 76 65 77 / 30 20 30 60 MCO 65 78 66 78 / 20 30 30 60 MLB 66 77 66 77 / 30 30 30 60 VRB 67 79 68 80 / 60 30 30 60 LEE 64 79 65 77 / 20 30 40 60 SFB 64 78 65 78 / 20 30 30 60 ORL 65 79 66 78 / 20 30 30 60 FPR 67 78 67 80 / 60 30 30 60 && .MLB WATCHES/WARNINGS/ADVISORIES... FL...None. AM...Small Craft Advisory until 10 PM EST this evening for AMZ570-572. && $$ UPDATE...Heil AVIATION...Law
Area Forecast Discussion
National Weather Service Marquette MI
702 PM EST Fri Dec 27 2024 .KEY MESSAGES... - Widespread rain will move in to the region tonight and linger Saturday. - Areas of fog, locally dense (reducing vis to 1/4 statute mile), continue through at least Saturday. - Unseasonably mild temperatures continue through Monday with highs averaging 10-20 degrees above normal and lows around 20 degrees above normal. - Temperatures trending back to normal by New Year`s Day with lake effect snow developing in the northwest wind snow belts. && .SHORT TERM /THROUGH SATURDAY/... Issued at 155 PM EST Fri Dec 27 2024 A soupie day has taken place across central and parts of eastern Upper Michigan thanks to the a warm, moist airmass aided by upslope flow. The lowest visibility has been observed via webcams across higher terrain areas of central Upper Michigan. Pockets of light rain/drizzle have also been noted thanks to low level isentropic ascent through this moist layer. Daytime temps have been observed well into the 30s across the region. Board troughing across western CONUS, as noted on GOES water vapor and RAP analysis, will continue pressing eastward tonight and Saturday. A shortwave embedded in this trough stretching across the Plains will amplify in response to favorable left exit region jet dynamics, resulting in a surface low developing today then lifting northeast into the Upper Great Lakes overnight into Saturday. Ahead of this wave, low level isentropic ascent within a saturated airmass will continue to support areas of low visibility and drizzle/rain for the remainder of today, mainly focused across central and eastern Upper Michigan. Lowest visibilities will be focused in the central portions, where light southeasterly flow will support upslope flow. This evening though, winds become more easterly as the upstream low lifts into the region. This may result in improving visibilities at least until tonight when they drop again. Widespread light rain is expected to lift north to south through the forecast area overnight and then ending south to north through the day Saturday. As noted by previous discussions, abundant moisture will be available with this system. However, with the progressive nature of the system, QPF is likely to remain less than an inch, so hydro concerns are not expected. Basin average QPF is expected to range from 0.25-0.75". Expecting continued fog, especially central Upper Michigan where upslope flow could support some dense areas into Saturday. Opted to extend the Dense Fog Advisory through 12z Saturday. Overnight lows are expected to remain above freezing in the mid 30s across the forecast area tonight and remain well above normal Saturday with highs in the mid 30s to low 40s. && .LONG TERM /SATURDAY NIGHT THROUGH FRIDAY/... Issued at 354 PM EST Fri Dec 27 2024 The long term forecast will be driven by a 500mb pattern of building ridging over the Rocky Mountains and longwave troughing over the eastern CONUS with a number of shortwaves pivoting around the core of the longwave trough as it moves from the Canadian Prairie through Ontario throughout the week. Flow aloft becoming more northwesterly will allow for a cooler airmass to flow into the Upper Great Lakes region, bringing temperatures back down to seasonal by the middle of the week and potentially cooler than normal by the end of next week. While synoptic snowfall seems to elude the region for the most part, cooler air aloft will support the return of lake effect snowfall, primarily in the northwesterly belts. Saturday night, rain will finish lifting to the northeast with sub- 10% chances of precipitation in the 06Z-12Z time period per the LREF. Throughout the overnight and Sunday morning period, shortwave troughing will pivot from OK/AR to the Chicago metro, supporting a deepening mid-990s to low 1000s mb low pressure pivoting through Lower Michigan and Lake Huron before lifting northeast into Canada. The NBM carries 20% chances of light precipitation in the far eastern UP with this system, with temperatures falling towards the freezing mark, there`s chances that the precip could fall as rain or snow. However, regardless of exact precip type, the LREF only gives 15% or less chances of the eastern UP seeing a half inch of snowfall accumulation prior to 12Z Monday, so even a "worst case scenario" would not be particularly impactful. The final days of 2024 into the beginning of 2025 will see cooling temperatures as 500mb heights aloft fall with the core of longwave troughing moving near the UP. With Lake Superior remaining around 5 C, the target for 850mb temperatures to support lake effect snow will be around -8C. By the time of the 25th anniversary of Y2K, the LREF shows 850mb temperatures over 90% likely over the west half of Lake Superior, spreading across the rest of the lake by the afternoon of the 1st. A return of lake effect snow will help bring the snowpack back after the toll taken on the snowpack by this week`s warmth and rain. Ensembles are coalescing around the 925mb wind direction being NWerly, the Canadian ensemble falling in line with the other ensembles in showing the NWerly pattern. However, uncertainty in the availability of low level moisture (tied to the shortwave evolution elsewhere outside of the UP influencing moisture transport) will keep the details of snowfall rates and impacts muddy. && .AVIATION /00Z TAFS THROUGH 00Z SUNDAY/... Issued at 701 PM EST Fri Dec 27 2024 Abundant low level moisture is producing fog and stratus that will continue into Saturday. Additionally, an area of low pressure will lift into the area tonight, bringing rain to all terminals into Saturday. KSAW will continue to experience LIFR to VLIFR conditions through Saturday afternoon, with conditions below airport minimums for much of that time. Late in the TAF period, KSAW will improve to IFR as westerly winds increase. KCMX will see low end MVFR this evening, before falling back to LIFR overnight. As the westerly winds increase Saturday afternoon, KCMX will improve to IFR. KIWD is currently shifting from VFR to IFR and these conditions should continue through the evening hours thanks to nearby terrain supporting downsloping flow. However, overnight conditions deteriorate to prevailing IFR, potentially LIFR by morning with conditions improving to IFR by afternoon. Westerly to southwesterly winds with gusts to 20 kts are expected Saturday afternoon. && .MARINE... Issued at 354 PM EST Fri Dec 27 2024 A low approaching from the southwest will bring the 20-25 kt southeasterly wind gusts in the east half of Lake Superior to near 30 kt with a few gale force gusts to 35 kt possible between Whitefish Point and Caribou Island (20-30% chance). Winds will quickly turn to the west/southwest as the low passes Saturday, with gusts to near 25 kt late Saturday into Saturday night. From there, the winds will remain mainly below 20 kt through the end of 2024 except for some northwesterly wind gusts to 25 kt over the eastern end of the lake Monday evening as a low pressure passes northeast through Lower Michigan and Lake Huron. Building high pressure to the west of Lake Superior while deep low pressure remains to the east of the Great Lakes will tighten the pressure gradient, encouraging near 25 kt winds broadly out of the northwest to kick off 2025. && .CLIMATE... Issued at 345 AM EST Wed Dec 25 2024 Record warm highs and lows at WFO MQT in Negaunee Township (records date back to 1959): Date High Low Dec. 27 42 (1994/2008) 32 (2008) Dec. 28 42 (1979) 34 (2003) Dec. 29 43 (1979) 31 (2022) && .MQT WATCHES/WARNINGS/ADVISORIES... Upper Michigan... Dense Fog Advisory until 7 AM EST /6 AM CST/ Saturday for MIZ004>006-010>013. Lake Superior... None. Lake Michigan... None. && $$ SHORT TERM...JTP LONG TERM...GS AVIATION...RM MARINE...GS CLIMATE...