Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 03/06/19

Area Forecast Discussion...UPDATED
National Weather Service Albuquerque NM
606 PM MST Tue Mar 5 2019 .UPDATE... Freezing fog has developed around KLVS again this evening, so have added FZFG to the Wx grid tonight and have also updated the sky grid based on current trends. It`s unclear how long the fzfg will last as winds will vary from SSE (which would favor it persisting) to SSW (where the downslope component should help eradicate it). Will monitor for a bit before deciding on a Freezing Fog Advisory. Regardless of visibility, any freezing fog can be dangerous, and those in the area should use caution. ZFP already out. 34 && .PREV DISCUSSION...447 PM MST Tue Mar 5 2019... .AVIATION... 00Z TAF CYCLE Though the low clouds across eastern NM shrunk in coverage somewhat this afternoon, a batch remains over EC NM and this batch will be moving back over KLVS at any moment. It is expected that IFR/LIFR cigs at KLVS will persist through the overnight hours. Do not expect a repeat of FZFG at KLVS tonight, but only moderate confidence exists. Low clouds have just barely cleared out over KTCC, and it is expected that they will not fill back in tonight, though confidence is lower here. Otherwise, VFR conditions are expected at remaining TAF sites. High clouds will continue to stream over northern NM overnight. Southwest winds will increase on Wednesday, with gusts near 30 kts likely across much of western NM and along and just east of the central mountain chain. These winds should help clear out any remaining low clouds across eastern NM by mid morning. 34 && .PREV DISCUSSION...300 PM MST Tue Mar 5 2019... .SYNOPSIS... Stubborn low clouds over east central New Mexico will continue to slowly erode tonight while mid to high level clouds move from west to east over the north. Overnight low temperatures will be warmer. A storm system passing to the north of New Mexico will bring rain and high elevation snow to the northwest and north central Wednesday through Thursday along with windy weather Thursday afternoon. Another storm system will bring strong winds, rain and high elevation snow to most of northern and central New Mexico Friday into Saturday. Daytime temperatures will finally rise above average Wednesday through Friday but dive 5 to 10 degrees below normal Saturday. Another relatively wet storm system is possible early next week. && .DISCUSSION... An area of low clouds over east central New Mexico continues to slowly erode this afternoon. The HRRR indicates this trend will persist but some low level moisture may pile up along the east slopes/highlands from the Springer area to Raton and along the Colorado border east of Raton this evening before it`s finally done. Overnight low temperatures to be warmer nearly everywhere in the forecast area. A storm system passing to the north of New Mexico will bring rain and high elevation snow to the northwest and north central starting Wednesday and continuing through Thursday. Potential for a few lightning strikes Wednesday northwest and north central but NAM12 expands the potential areal coverage and instability Thursday. Did not include any thunderstorms in the wx grids with this package but later shifts may decide to if model trends persist. Snow amounts in the San Juans may reach 4-8 inches above 8000 feet by late Thursday, with the majority of it accumulating Wednesday night. Therefore holding off on issuing an advisory for now. Winds to strengthen Thursday, becoming strongest along and south of Interstate 40 and along and east of Interstate 25 and may reach speeds that would trigger issuance of wind advisories. Another storm system crosses New Mexico from west to east Friday and Friday night bringing rain and high elevation snow to most of the forecast area. In addition, strong winds are forecast to become more widespread Friday, when there is potential for localized damaging wind speeds especially from the south central to the east central. Northwest winds look to be quite strong Saturday from the central mountain chain over much of the east as the storm departs. Daytime temperatures warm to above average Wednesday through Friday, with an assist by the strong downslope winds. A backdoor front may flirt with the far northeast Thursday/Friday which could raise havoc with temperatures but the 18Z NAM12 has backed off on the southwestward progress the 12Z run suggested. Another relatively wet storm system is forecast for early next week. && .FIRE WEATHER... ...CRITICAL FIRE WEATHER CONDITIONS THURSDAY EAST CENTRAL PLAINS AND POSSIBLY THE LOWER RIO GRANDE VALLEY... The Arctic airmass across the eastern plains is modifying rapidly this afternoon and a warming trend is underway areawide that will continue through Thursday most areas and send temperatures back above normal by Wednesday. Increasing westerlies Wed/Thu in advance of a potent Pacific trough will result in critical fire weather conditions by Thursday afternoon across portions of the eastern plains as well as portions of the lower Rio Grande Valley. Even stronger winds will develop Friday in advance of the Pacific trough, but moisture will increase and humidity will not exceed critical threshold. The Pacific trough will bring cooler temperatures and chances for wetting precipitation through Saturday morning, mainly to the mountains and surrounding highlands. Strong winds will persist Saturday behind the exiting trough, especially across the eastern plains where humidity may also exceed critical threshold. However, Haines values of 2-3 and temperatures at or below normal will limit critical fire weather conditions Saturday. Look for a break Sunday followed by a wetter system early next week, which may bring good chances for wetting precipitation to much of the area. 11 && .ABQ WATCHES/WARNINGS/ADVISORIES... Fire Weather Watch from Thursday afternoon through Thursday evening for the following zones... NMZ108. && $$ 34
Area Forecast Discussion
National Weather Service Boston/Norton MA
902 PM EST Tue Mar 5 2019 .SYNOPSIS... Unseasonably cold but mainly dry weather will prevail through Thursday with slowly moderating temperatures Friday. High pressure builds to the north Saturday, then a strong storm moves through the Great Lakes Sunday which will likely bring a period of rain to the region, possibly starting as a wintry mix in the interior. Drier air moves in behind the storm on Monday. && .NEAR TERM /UNTIL 6 AM WEDNESDAY MORNING/... 9 PM Update... Forecast is in good shape. Cold front is making its way through western New England and should be moving offshore by 06Z or so. There are a few snow showers in the Catskills which may make the trip over the Berkshires per high-res guidance, but probably not much farther than that with relatively weak winds at lower levels and a dry airmass in place. That said, HREF and HRRR point toward possibility of scattered snow showers redeveloping around outer Cape just after midnight due to some ocean enhancement. Forecast has this all handled well so no major changes made. Cold advection brings 850 mb temps down to -18 to -20C by morning. Lows will be mostly in the teens with some single numbers of the higher terrain in MA. Wind chills by morning in the single numbers, dropping below zero over higher terrain. && .SHORT TERM /6 AM WEDNESDAY MORNING THROUGH WEDNESDAY NIGHT/... Wednesday... Mid level trough axis and core of coldest air aloft will be over New Eng. Sunshine in the morning, then expect diurnal cu to develop late morning into the afternoon. Dry weather expected but can`t rule out a few flurries in the higher terrain. 850 mb temps around -18C so highs will be mostly in the 20s, with upper teens in the Berkshires. Gusty NW winds with gusts to 25-30 mph will add to the chill. Wednesday night... Shortwave trough axis moves offshore, but a secondary shortwave will be approaching from the NW which will reinforce arctic airmass across New Eng. Mainly dry weather expected but continued very cold. Lows will be mostly in the single numbers, with teens near the coast. && .LONG TERM /THURSDAY THROUGH TUESDAY/... This portion of the forecast will likely feature a pair of mid level cutoffs within the northern stream of the mid level flow, and a nearly zonal flow over the southern USA much of this week. Then the pattern will hinge upon how much energy can move into the base of the western trough, and the resulting amplification within the northern and southern streams. This will not only impact the strength of a low pressure expected to develop over the Plains states late this weekend, but how quickly our region will warm up. 05/12Z guidance is in reasonable agreement for this time range, but there is enough variance to not set the forecast details in stone just yet. Mainly dry weather in store for southern New England into Saturday. A low pressure is expected to pass well south of our region Saturday. This may have enough reach to impact the outer southern coastal waters with some rain, but there is an even lower risk for precipitation on the islands. Will need to monitor this track closely over the coming days. Our next chance for more substantial precipitation looks to be sometime late Saturday night into Sunday night as a low pressure moves into the Great Lakes. Depending upon the exact timing, there could be some snow of the front-end, which then transitions to rain during the day Sunday before ending Sunday night. Temperatures should remain below normal through Saturday night, then trend to near to above normal by Monday into Tuesday. && .AVIATION /02Z WEDNESDAY THROUGH SUNDAY/... Forecaster Confidence Levels... Low - less than 30 percent. Moderate - 30 to 60 percent. High - greater than 60 percent. Short Term /through Wednesday Night/...High confidence. Tonight... A period of VFR cigs 4-6k ft, clearing late. Isold -SHSN, mainly north of the Pike. Wind shift to NW with gusts to 20 kt developing along the coast after midnight. Wednesday... VFR with sct-bkn cigs around 5k ft developing in the afternoon. NW gusts to 25 kt. Wednesday night... VFR with diminishing wind. KBOS Terminal...High confidence in TAF. Low risk for a -SHSN between about 05-08Z. Little to no accumulation. KBDL Terminal...High confidence in TAF. Outlook /Thursday through Sunday/... Friday through Friday Night: VFR. Breezy. Saturday: VFR. Saturday Night: VFR. Breezy. Chance SHSN, slight chance FZRA. Sunday: MVFR/IFR conditions possible. Breezy. SHRA, chance SHSN, slight chance FZRA. Sunday Night: Mainly VFR, with local IFR possible. Windy with local gusts up to 30 kt. Slight chance SHRA, chance FZRA. Monday: Breezy. && .MARINE... Forecaster Confidence Levels... Low - less than 30 percent. Moderate - 30 to 60 percent. High - greater than 60 percent. Short Term /through Wednesday Night/...High confidence. Winds already reaching 25kt on outer south coastal waters per buoys and on Nantucket Sound per recent ferry report, so moved up timing of SCA for these areas. Otherwise, cold front moves through late tonight with surge of gusty NW winds late tonight into Wednesday, with SCAs going into effect on remainder of MA/RI waters. Winds slowly diminish Wed night. Areas of freezing spray developing on the open waters late tonight into Wednesday evening. Outlook /Thursday through Sunday/... Friday: Winds less than 25 kt. Friday Night: Winds less than 25 kt. Slight chance of rain. Saturday: Winds less than 25 kt. Seas locally approaching 5 ft. Saturday Night: Winds less than 25 kt. Areas of seas approaching 5 ft. Sunday: Low risk for Small Craft Advisory winds with gusts up to 30 kt. Areas of rough seas. Rain showers, chance of snow showers, slight chance of freezing rain. Sunday Night: Moderate risk for Small Craft Advisory winds with local gusts up to 30 kt. Rough seas up to 10 ft. Rain showers. Monday: Low risk for Small Craft Advisory winds with gusts up to 20 kt. Rough seas up to 9 ft. && .BOX WATCHES/WARNINGS/ADVISORIES... CT...None. MA...None. RI...None. MARINE...Small Craft Advisory from 4 AM Wednesday to 5 AM EST Thursday for ANZ232. Small Craft Advisory from 4 AM Wednesday to 1 AM EST Thursday for ANZ231-233>235-237-251. Small Craft Advisory from 4 AM to 7 PM EST Wednesday for ANZ230-236. Small Craft Advisory from 4 AM Wednesday to 7 AM EST Thursday for ANZ250. Small Craft Advisory until 7 AM EST Thursday for ANZ254>256. && $$ SYNOPSIS...Belk/KJC NEAR TERM...JWD SHORT TERM...KJC LONG TERM...Belk AVIATION...Belk/KJC MARINE...JWD
Area Forecast Discussion
National Weather Service Caribou ME
1040 PM EST Tue Mar 5 2019 .SYNOPSIS... An upper level disturbance will cross the area overnight into Wednesday. High pressure builds Wednesday night into Friday. && .NEAR TERM /THROUGH WEDNESDAY/... 1017 PM Update... Hrly temps/dewpoints were adjusted once again to fit the latest conditions. Temps have dropped off quickly w/the latest arctic airmass settling across the region. Temps back across NW Maine are down to -6 at Clayton Lake(K40B) as of 1015 pm. Presque Isle came in w/-2F. Single numbers elsewhere across northern areas w/lower teens in the central and downeast areas. Decided to lower temps more in the low lying and sheltered areas overnight. Disturbance seen on IR satl imagery moving e across southern Quebec. At the sfc is weak low pres that coincides w/the upper disturbance. Some light returns showing up in southern Maine. HRRR and the latest RAP show some light snow developing overnight across the central and downeast areas and then trying to edge newd by Wed morning. The daycrew`s assessment looks in line and did not change the precip chance w/this update. Previous Discussion... Clearing skies this evening will promote quick radiational cooling this evening, but will slow in southern zones later tonight as clouds thicken from the west. An upper level trough will approach from Quebec overnight and amplify. This will induce weak cyclogenesis on the cyclonic side of the upper trough in the Gulf of Maine. As this occurs, a brief period of snow will develop across the southern half of the forecast area. Any snowfall amounts will be less than an inch and confidence is not high enough to assign even likely pops at this time. Further north, the radiational cooling will continue through the night and will yield subzero readings by daybreak across Aroostook County. Cannot rule out a few readings dropping towards minus 15F in some of the usually colder locations of northern Aroostook. Favored some of the coldest bias corrected guidance in the forecast. For Wednesday, the big issue will surface- based instability as the unusually cold upper trough crosses the area. Steep lapse rates up to H700 and available H850 moisture will produce SBCAPE over 100 J/kg at times. Snow showers will be a threat across the entire area and some could be briefly intense. The snow squall parameter is flashing the best signals towards northern Aroostook County and the western mountains, but can`t rule out a strong snow shower for Bangor on Wednesday afternoon. Do like the idea of the strongest snow shower activity in northern Aroostook as lift with the upper trough will be best in that area. Used H850 temps as a guide for Wednesday`s high due to the expected mixing. In terms of winds, the synoptic scale winds pick up late in the day...mitigating concerns about blowing snow. However, gusts will snow showers could exceed 30 mph. && .SHORT TERM /WEDNESDAY NIGHT THROUGH FRIDAY/... High pressure at the surface will be moving off the Mid-Atlantic coast Wednesday night as an upper trough lifts northeast of the area. Any flurries and snow showers early Wednesday evening should taper off as the air stabilizes. Otherwise, Wednesday night will be partly cloudy. This will be followed by a partly sunny and very cold day Thursday as the upper trough remains nearby to the northeast. Thursday night will then be partly cloudy and very cold with high pressure to our south. Dry weather is expected to persist through Friday with high pressure south of the area and an upper trough remaining over eastern Canada. Temperatures Friday will be a little milder than Thursday but still about ten degrees below average for this time of year. && .LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/... High pressure will build over the area Friday night into Saturday. This will bring a bright, sunny and tranquil day on Saturday with some moderation in temperatures during the midday and afternoon. The high will slide east of the area Sunday as a large low pressure system lifts north into the Great Lakes area. Sunday will likely begin mostly sunny and tranquil. Clouds will then increase during the day ahead of a warm front pushing east of the Great Lakes low. Snow may spread into the area Sunday afternoon, likely changing to rain Downeast as warmer air gets pulled north. A changeover from snow to rain may push north Sunday evening, possibly reaching northern areas by late evening. However, the occlusion will quickly push through as the low, tracking to our northwest, pulls drier air northward. This may end precipitation over the north before much rain falls. Monday should then be cloudy to partly sunny and mild as a corridor or mild air slides across the area with the dry intrusion aloft. A cold front will reach the area Tuesday bringing in moderately cooler air and a chance for some snow showers under a cloudy to partly sunny sky. && .AVIATION /03Z WEDNESDAY THROUGH SUNDAY/... NEAR TERM: The prevailing condition will be VFR outside of snowshowers. Snowshowers may cause IFR vis late tonight into early Wednesday towards BGR and BHB. Shorter duration snowshowers may affect all sites Wednesday afternoon, but vis could temporarily drop to LIFR. SHORT TERM: MVFR conditions north and VFR conditions Downeast are expected Wednesday night. Conditions are expected to be mostly VFR Thursday into Friday but may occasionally drop to MVFR across the far north in lower stratocumulus clouds during this period. VFR conditions in a mostly clear sky are expected Saturday. && .MARINE... NEAR TERM: A Small Craft Advisory will likely be required by Wednesday afternoon due to winds. Light freezing spray is expected later tonight into Wednesday morning. SHORT TERM: A SCA will likely be needed Thursday night into Friday night for northwest to west winds gusting up to 30 kt. Winds should diminish Saturday as high pressure builds over. Winds should remain light into Sunday, but then may increase to a SCA or gale late Sunday into Sunday night ahead of an occluded front. && .CAR WATCHES/WARNINGS/ADVISORIES... ME...None. MARINE...None. && $$ Near Term...Hewitt
Area Forecast Discussion
National Weather Service Hastings NE
549 PM CST Tue Mar 5 2019 .SHORT TERM...(This evening through Wednesday) Issued at 334 PM CST Tue Mar 5 2019 Aloft: Moderately-amplified flow was over the CONUS per RAP tropopause analyses and aircraft obs...with a trof over the E Pac...a ridge over the Rckys...and a Hudson Bay low and trof over the Ern USA. NW flow was over the Cntrl Plns with rising heights as the ridge approaches. This ridge will crest over the rgn around sunset tomorrow. Surface: High pres was over KS. An Arctic front was over SA/MB. The high will slide into AR/MO tonight on its way into the Gulf Coast states tomorrow. The Arctic front will move SE thru tomorrow...crossing the CWA in the afternoon. However...the thermal contrast along tail end of the cold front will weaken. So this front will be little more than a wind shift. Nrn Plns high pres will build in behind the front. Tonight: Mainly clear to start...but increasing clds espcly after midnight. Should be m/cldy by dawn. Used consensus of all guidance for lows which has been performing best over the last wk. Wed: M/cldy. Not as cold...but still 15F below normal. .LONG TERM...(Wednesday night through Tuesday) Issued at 334 PM CST Tue Mar 5 2019 Aloft: A weak/low-amplitude shortwave trof will move thru Wed ngt into Thu AM. Heights will rise in its wake with the Wrn ridge moving thru here Fri as a much deeper trof moves onshore into CA and thru the Desert SW. The last 2 runs of the GFS/GFS-FV3/EC/ GEM/UKMET cont in unison on becoming negatively tilted with a low forming over NEB Sat. Quite a bit of spread develops Sun. The GFS /GFS-FV3 runs have cyclonic NW flow and troffing over NEB/KS while the GEM/UKMET/EC runs maintain SW flow with a broad ridge as the next deep low drops down the CA coast. This lowers fcst confidence Sun-Tue. Surface: Wed night the pres grad will increase as high pres drops into the Nrn Plns and weak low pres ejects out of CO into OK. Thu-Fri high pres will prevail over the Ern USA/Canada...and it will extend back into NEB/KS. Lee cyclogenesis will occur Fri afternoon. This low will cross KS from 12 AM-12 PM Sat. High pres will build in Sun and probably slip E of the rgn Mon-Tue. Temps: Contd much colder than normal...but not nearly as cold as we`ve been experiencing. We will begin seeing a lot more 30s over S- cntrl NEB and 40s over N-cntrl KS. Sat looks like temps will finally climb above 32F at GRI...and all the other locations that haven`t seen 32F since Feb 13th. Precip: We are still expecting a band of 1-4" of snow mainly N of I- 80 Wed night into Thu AM. The highest amts of 3-4" cont to be expected from Ord-Greeley-Fullerton. Have initiated Situation Reports (available top of our website) as probability remains high we`ll need a Winter Wx Advisory. Fri night-Sat: The EC/GEM/GFS cont in unison that there will be a substantial warm nose with this sys. That means we are advertising too much snow at the onset. Given that this sys is still beyond 84 hrs...our fcst ptype algorithm conts to indicate snow at the leading edge of the precip shield that moves in Fri night. The more likely scenario is a mix of frzg rain/sleet changing to rain Sat for most areas. The mdl consensus is that a shield of mix precip will form and move from SW-NE Fri night into Sat AM...with this trof rapidly swinging thru with negative tilt. The upr low is fcst to close off just N or E of the CWA. That means a quick shutoff to the precip by midday Sat as the dry slot moves in. There are still a minority of mdl runs indicating a low could close off over SE NEB. If that occurs...that could prolong the precip into the afternoon E of Hwy 281. But it`s doubtful there will be enough cold air around for snow. Rainfall amts cont to be of concern. The faster this sys moves thru the better. Any substantive rain falling into such deep snow will significantly increase its weight. That could stress buildings with flat roofs to the point of partial failure/ collapse. Snow will not be the dominant ptype this this sys. In fact... there is potential we could see warning-level amts of frzg rain (at least 1/4"). It has been so cold for so long...frzg rain could even cont after air temps even climb above 32F. Can`t rule out a couple rumbles of thunder Fri night-Sat AM over the SE fringe of the CWA (Beloit-Hebron). Suggest everyone cont to closely monitor this storm. Winds: Incrsd winds above MOS Wed night. Have seen this many times when E winds end up stronger than fcst as the pres gradient tightens from high pres sinking into the Nrn Plns and a warm front is stalled over KS/OK. Sat night into Sun AM will be windy and the fcst probably doesn`t fully reflect how windy it will be just yet. We`re probably looking at 20-30 mph G40-50. If we get warning-level ice...this could result in sct power outages from bringing down tree branches. Pattern: The EC/GFS/GEM ensemble means are all fcstg a major pattern change in the 10-15 day time frame (Mar 15-20). The trof that has persisted over the Wrn USA for the last 30 days appears like it could be replaced by a ridge. That would mean temps returning to near normal...and favoring above normal at times as periods of downslope warming could occur. && .AVIATION...(For the 00Z KGRI/KEAR TAFS through 00Z Wednesday) Issued at 539 PM CST Tue Mar 5 2019 VFR conditions are forecast. However, ceilings will develop and lower as a shortwave trough approaches. Any ceilings lower than VFR should hold off until just after the valid time of the forecast. && .CLIMATE... Issued at 526 AM CST Tue Mar 5 2019 ..Various notes on our ongoing remarkably-cold snap (for Grand Island/Hastings, our two primary long-term climate data sites).. SECOND-COLDEST OPENING WEEK OF MARCH VERY LIKELY: - Based on observed data through these first few days and our current official forecast through the 7th, both Grand Island/Hastings are well on their way to enduring the 2nd- coldest opening week of March on record. The top spot currently belongs to 1960, when the first week averaged an incredible 28 degrees below normal at Grand Island, and 26 degrees below normal at Hastings. LONGEST STREAK AT-OR-BELOW FREEZING IN DECADES? - Today will mark the 19th-consecutive day that both Grand Island and Hastings will fail to climb above the freezing mark (32 degrees). - Based on our official forecast, this streak of at-or-below freezing days should last through at least March 8th (Friday), which would bring it up to 22 days. - The last time Grand Island (GRI) had a 22+ day streak of at-or- below freezing was 26 years ago, with a 22-day stretch from Dec. 9- 30, 1983. The record-longest streak is 31 days from Jan. 22-Feb. 21, 1936. - The last time Hastings (HSI) had a 22+ day streak of at-or- below freezing was actually the record-longest streak of 30 days, way back from Jan. 23-Feb. 21, 1936. && .GID WATCHES/WARNINGS/ADVISORIES... NE...None. KS...None. && $$ SHORT TERM...Kelley LONG TERM...Kelley AVIATION...Heinlein CLIMATE...JCB/Pfannkuch
Area Forecast Discussion
National Weather Service Wilmington NC
919 PM EST Tue Mar 5 2019 .SYNOPSIS... A dry cold front tonight will usher Arctic air into the region, bringing a couple freezing mornings both Wednesday and Thursday. Expect a warming trend into the weekend with increasing clouds and chance of showers late Friday and again on Sunday ahead of approaching cold front. && .NEAR TERM /THROUGH WEDNESDAY NIGHT/... As of 930 PM Monday...We`re in the lull ahead of the secondary arctic front which has recently moved through Charlotte, Asheboro, and Greensboro where dewpoints are plunging into the single digits. Light winds have allowed some impressive radiational cooling to occur in the cool prefrontal airmass and several spots across eastern SC (Georgetown airport, Conway, Kingstree) are already down to freezing. Look for temperatures to jump by 3-5 degrees when the front arrives simply due to mechanical mixing of the boundary layer. Latest HRRR/RAP trends indicate the front should move across our forecast area between midnight and 2 AM. Temperatures should then fall due to cold advection overnight through daybreak Wednesday. I`ve made no additional changes to overnight low temps, although I still have concerns that I may be too cold in spots given the amount of boundary layer mixing anticipated to occur in the post-frontal regime. Discussion from 630 PM follows... Back edge of the dense low clouds is clearing off the South Carolina coast now. However scattered clouds are expected to redevelop between 9-11 PM as lapse rates steepen with the approach of the mid level trough dangling southward from the main low up in Quebec. The top of the moisture should extend to near 8000 feet AGL where temperatures will be around -10C, which means radar could pick up some virga flurries overnight. Increasingly dry sub-cloud conditions are expected to evaporate any snow before it makes it to the ground. There may be problems with the 18Z GFS initialization of excessive snow cover across the eastern Carolinas. This appears to manifest itself as a very cold, moist boundary layer that continues through the night. I`m actually discarding the GFS at this time and am relying on other model guidance for temperatures, and have therefore raised our forecast lows by about 2 degrees across the board. Recent HRRR runs even indicate I may need to add another couple degrees. Cold 850 mb temps (-7C to -9C) arriving late tonight still appear to guarantee a freeze, and no changes have been made to the freeze warning at this time. -TRA Discussion from 300 PM follows... Upper trough axis upstream, slated to transit SE NC and NE SC late tonight, will carry an impulse containing vertical circulations, but limited moisture, mainly 3z-5z. Surface dewpoint depressions of around 10 degrees should evaporate most flurries and the air mass is too cold aloft for sleet. Even so, a few `flurry sightings` late tonight should not be a complete shock. GOES Day Cloud Phase channel, shows well the cumulus in the base of trough dropping across snowpack in IA, IN, soon into KY and ern TN. `Freeze Warning` posted area wide, as even the beaches drop near, or below freezing, as Arctic air spills in late tonight. Temperatures to drop below freezing in most areas after 3 AM if not a little sooner, rising slowly in cold sunshine early Wednesday. Dewpoints to take a pronounced dip after 6z, reaching the teens into daybreak Wednesday and min-RH Wednesday around 30 percent even in the chilly air mass. Moderate NW breezes Wednesday morning in CAA, will produce wind chills in the lower 20s at school bus stops, and area-wide. A Freeze Warning will be needed again for early Thursday, but considerably less wind as the core of high pressure nears. && .SHORT TERM /THURSDAY THROUGH FRIDAY NIGHT/... As of 300 PM Tuesday...Extended period will be very similar to what has been happening for much of the winter. A strong mid- latitude cyclone will emerge from the Southwest and lift across the Plains into the Great Lakes. The mid-level pattern will transition from progressive Sat to more amplified Sun and Mon, lifting a front stalled in the area on Sat north of the area on Sun. The cyclone will pass well northwest of the area Sun night into Mon, dragging a cold front across the area and off the coast. Modest cold advection setups Mon night and Tue as modified Canadian high builds in. -Temperatures above normal Sat through Mon. -Cold advection later Mon and Mon night will drop temperatures to near normal on Tue. -Rain chances increase Sat as front lifts north through the area but best chances will be later Sun in warm sector ahead of the front. -Potential exists for high shear/low CAPE severe event on Sun, but confidence is low given large uncertainties. && .LONG TERM /SATURDAY THROUGH TUESDAY/... As of 300 PM Tuesday...Progressive pattern through the period with shortwave riding by on Fri. This will lead to an increase in clouds and chc of pcp late Fri into Fri night. Ridge building in for Saturday should provide drier weather, but models are hinting at low clouds possible into Saturday as front drops down from the north. This front will return north Sat night as next shortwave drives a front eastward into the Carolinas. Warm and moist air on Sunday with temps into the 70s ahead of cold front should help to produce some showers. High pressure to follow with westerly downslope flow behind front on Monday will keep warm temps across the area until later in the day when deeper N-NW advects cooler air into the area for Mon night into Tues, bringing temps closer to normal. Overall expect temps near normal to start and end the period, but running above normal in warming through much of the period. Should see a fair amount of clouds around with best chc of pcp Fri night and then again on Sunday. && .AVIATION /00Z WEDNESDAY THROUGH SUNDAY/... As of 00Z....Modified arctic air will spill into the region through the overnight hours. There will be enough cold air advection to keep the winds above 5 kts. A Northwest wind is in store for Wednesday, with nearly clear skies. Extended Outlook...VFR Wed through Sat. && .MARINE... As of 930 PM Monday...Offshore winds should veer north when the arctic cold front pushes off the coast shortly after midnight, with speeds increasing to 20-25 kt. Current forecast looks good and no changes are planned overnight. Discussion from 630 PM follows... No significant changes are needed to the marine wind/wave forecast at this time. Discussion from 300 PM follows... Strong NW wind and cold air will make dangerous marine conditions overnight and early Wednesday, especially offshore with 5-6 foot seas and 30 kt gusts. NW wind waves will interact with N waves of nearly equal wave periods of 5-6 seconds making for a mess overall. Winds and seas to improve beginning late Wednesday, and by Wednesday night, NW winds 8-13 kt and seas 1-3 feet, highest offshore. Dry this period so no visibility restrictions expected. Light northerly flow Thu will become southerly in the afternoon and evening as high pressure to the north shifts offshore. Gradient remains weak and southerly flow will remain under 10 kt through Fri night. Weak front drops south across the early Sat with light northerly flow setting up. Light winds and changing direction will keep seas 2 ft or less Thu through Sat. Stalled boundary slowly lifts back north Sun morning. Gradient starts to increase as cold front approaches and southerly flow jumps to a solid 20 kt. Small Craft Advisory headline may be needed later Sun and Sun night. Development of southerly flow Sat night into Sun coupled with increasing wind speeds will build seas to 3 to 5 ft by Sun morning with potential for 4 to 7 ft later Sun and Sun night. && .ILM WATCHES/WARNINGS/ADVISORIES... SC...Freeze Warning from 2 AM to 9 AM EST Wednesday for SCZ017-023- 024-032-033-039-054>056-058-059. NC...Freeze Warning from 2 AM to 9 AM EST Wednesday for NCZ087-096- 099-105>110. MARINE...Small Craft Advisory until 2 PM EST Wednesday for AMZ250-252- 254-256. && $$ SYNOPSIS...III NEAR TERM...08/TRA SHORT TERM...III LONG TERM...III AVIATION...DL