Aikyam-Lab/Synoptic-Bench huggingface dataset:
MVFR ceilings widespread across forecast area at this time with patchy IFR ceilings where freezing drizzle/drizzle/fog continues to occur. Patchy freezing drizzle has been reported across portions of nern OK and wrn AR but this activity has been light enough and intermittent enough to not cause any impacts in our forecast area. Although we still expected some drying in the low levels across nern OK/nwrn AR this afternoon, this trend has been slower than expected. Thus, we have adjusted forecast accordingly with clouds slower to diminish, and freezing drizzle/ drizzle to continue into late afternoon.
The other big story obviously is the dangerous cold temperatures that settle over the area this weekend as a 1052mb arctic high pressure center moves directly overhead.
This has resulted in temperatures holding in the lower single digits above zero in our southern areas, and holding in the lower digits below zero over the northern half of our area. Light snow, possibly just a dusting, is expected to move in after 8 PM, from west to east, and as it does so, the mainly accumulations should be shifting south as the wave encounters the ridge axis and frontogenesis shifts south along it's edge. Sunday, with a cold start, cold advection and unmodified arctic air sweeping in (much like today), highs will fall short of zero in Iowa, and only reach the lower single digits above in Illinois.
This high will slide down into the central plains on New Years Day tightening the pressure gradient a little across Middle Tennessee, creating persistent steady winds of 10-15mph for New Years Eve into the following morning.
Winds will weaken to around 5 mph while temperatures fall into the low single digits with areas north of Dayton dropping a bit below zero.
350 PM EST Sat Dec 30 2017 A deck of clouds has formed and lingered across the Lower and part of the Middle Keys this afternoon. Temperatures are in the low 70s across the island chain and dew points are in the low 60s, and have fallen slightly since this morning. Lows tonight and Sunday night will drop to the low to mid 60s. Highs Sunday are on track to reach the low 70s. A new cold front will begin to push into North Florida Sunday night.
MORE FREEZING DRIZZLE EXPECTED OVERNIGHT WITH UP TO FOUR Shield of stratus was still largely intact late this afternoon across the region, except near the NM state line where deeper mixing was eroding the west edge of these clouds. This process should enhance moist ascent and garner a more definitive round of freezing drizzle mainly after midnight. Freezing drizzle should mix with or change to very light snow/flurries by early Sunday morning as the top of the saturated layer cools to -12C or lower. Concern thereafter is how much winds will slacken New Years Eve night as surface ridging builds south.
205 PM CST Sat Dec 30 2017 Water vapor satellite this afternoon shows a short wave trough over the Northern Rockies. The upper level flow will remain northwest as ridging remains anchored over the Rockies.
The cold front associated with this system will arrive too late to affect afternoon highs so expect another afternoon of above normal temperatures. Afternoon highs will be near normal across the north behind the cold front while the south is expected to remain mild.
If winds end up bing higher than expected in the ridges an advisory will be needed.
The Arctic high pressure center will nose down out of Canada into the Western Plains. At this point it seems like readings will be slightly less cold as warmer 925mb temps come in from the north.
On Sunday the broad upper level low centered over the Great Lakes region shifts east taking the coldest of the Arctic air mass over our area with it.
1003 AM CST Sat Dec 30 2017 Still could see some very light patchy freezing drizzle next hour or so, but expect no impacts. Patchy freezing mist/drizzle continues across the Interstate 44 corridor this morning behind the Arctic front. Will closely monitor this as temps are falling fast below freezing. There may be a few patchy spots of freezing drizzle or flurries along and immediately behind the front however it looks like it will not be enough to cause any impacts and will end soon. Temps tonight will crash into the single digits for lows as a strong area of high pressure builds south into the plains.
Satellite imagery reveals the center of circulation for the passing upper level low now situated just north of Havre. PN /ISSUED 420 AM MST Sat Dec 30 2017/ An Arctic front continues to retreat northeast across north- central Montana early this morning as low pressure approaches the region from the northwest.
By then, a trough will be working onshore which could bring some precipitation to the region by the latter half of the week. Upper level ridge continues to dominate the short term. The good news is it looks like things will be changing during this forecast period, since mid week a trough off the Pacific coast will work waves of energy onshore.
There is a chance after midnight of some freezing rain or drizzle across portions of southern Arkansas and north central Louisiana, when the surface temps drop below freezing, possibly impacting KELD and KMLU.
Unusually strong high pressure for this time of year is centered over the southern California and Arizona this morning. This area of high pressure will remain strong today and weaken slightly by Sunday.
217 PM EST Sat Dec 30 2017 Canadian high pressure across the region will be reinforced behind a dry cold front tonight. A broad upper level trough will remain over the eastern CONUS through tonight. A dry arctic cold front will move into the forecast area from the northwest this evening and shift east tonight. Some increase in moisture may occur Sunday and Sunday night with a weak inverted trough lingering in the wake of the cold front.
For the 12z TAFs: A cold front has moved through the area. Low level saturation may still be enough for light freezing drizzle or very light snow/flurries early this morning, but improving conditions are expected by midday/early afternoon. Cold front is expected to be through the area by sunrise this morning, with very cold air overspreading the area in its wake. There still appears to be a window, mainly this morning for some light freezing drizzle or even very light snow across much of the area. As we go through the night tonight, another surge of cold air moves south and with it we could see some light freezing drizzle or light snow redevelop across portions of western, central and southern Oklahoma into north Texas.
The reason behind this is that in many locations across the mid state region temperatures will be falling during the afternoon hours as an additional reinforcing cold air advection air mass builds into the region per dry cold frontal passage. An arctic cold front moves through today.
12Z sounding data sampled a 585dm H5 ridge centered directly over west central AZ this morning while H7 temperatures were peaking in a 8C-9C range.
226 PM CST Sat Dec 30 2017 Leading edge of arctic air/subfreezing temperatures was nearly to I-40 this hour with a few reports of flurries to the north.
The initial push of Arctic air has moved through the area with only far southeast OK into western AR remaining a bit above freezing. Radar/surface obs and reports have shown intermittent freezing drizzle and a bit of snow through the day so far, although the intensity has remained very light.
Patchy freezing mist/drizzle continues across the Interstate 44 corridor this morning behind the Arctic front. Will closely monitor this as temps are falling fast below freezing. There may be a few patchy spots of freezing drizzle or flurries along and immediately behind the front however it looks like it will not be enough to cause any impacts and will end soon. Temps tonight will crash into the single digits for lows as a strong area of high pressure builds south into the plains.
The clouds and diminishing winds will keep us "warmer" tonight so there is no wind chill advisory tonight except for the far western counties (Sauk, Iowa, Lafayette). Arctic high pressure will remain stationed over the Midwest. Low pressure over Hudson bay will keep the Great Lakes region under a fairly tight pressure gradient which will give us a prolonged period of brisk northwesterly winds in southern WI.
Cold advection will weaken overnight and the lower clouds and any lingering higher terrain flurries will move out. Wind chill values will be low overnight especially in the higher terrain, but appears they will not be low enough for any wind chill advisory.
1126 AM CST Sat Dec 30 2017 Last of the "warmer" air lingering south of I-70 late this morning, where temperatures are still close to 20 degrees. A cold front has recently cleared the forecast area to the southeast. Freezing drizzle has occasionally been reported along and just in the wake of the front. However, any remaining precipitation in the post frontal cloud cover should be trending toward flurries as the low-level moist layer cools sufficiently to contain ice nuclei. Otherwise, very cold conditions will return to the area as Arctic high pressure builds in behind the front.
1002 AM MST Sat Dec 30 2017 Upper level analysis has broad trof across the eastern CONUS with weak ridge over the Great Basin area. Snow will taper off and end tonight as arctic high pressure pushes into the Northern Plains.
305 PM CST Sat Dec 30 2017 (Tonight and Sunday) Conditions are becoming worse across the Big Country as freezing drizzle covers much of this area. Going with a Winter Weather Advisory across the Big Country, Concho Valley and Coleman and Brown counties until Noon Sunday for mainly freezing drizzle and some ice accumulations. However, models do hint at another band of possible freezing/frozen precipitation overnight across the I-10 corridor. Kept 20 percent pops for far southern areas overnight Sunday, with some ice pellets/freezing rain briefly.
930 AM MST Sat Dec 30 2017 Satellite imagery reveals the center of circulation for the passing upper level low now situated just north of Havre. CC /ISSUED 420 AM MST Sat Dec 30 2017/ An Arctic front continues to retreat northeast across north- central Montana early this morning as low pressure approaches the region from the northwest.
Could see some downward trend in lake effect snow shower intensity this afternoon, particularly well inland as contribution from passing upper trough wanes. Heavy Lake effect snow is expected to develop tonight as a trof extends east/west across Lake Michigan.
252 PM MST Sat Dec 30 2017 A low pressure system is forecast to weaken and exit the region to the southeast this evening with snow coming to an end by early evening for northeast Montana. Behind the low pressure system an arctic high pressure system is forecast to drop south along the Canadian and northern rockies ushering some very cold temperatures.
226 PM CST Sat Dec 30 2017 Main forecast story in the short term will lie with the bitterly cold arctic blast that will be settling into the region as a huge dome of high pressure moves slowly southeast through the Midwest and Plains states.
/issued 518 AM CST Sat Dec 30 2017/ An Arctic cold front had dropped into southern MO this morning. Given the inter-run consistency of the NAM and corroboration with the GFS and ECMWF, have issued a winter wx advisory for portions of north MS late tonight and early Sunday for light freezing rain/freezing drizzle and sleet. Subfreezing temps and wind should allow for efficient ice accretion on bridges and other elevated objects. Ice accumulation should remain less than 1/10 of an inch, and most likely closer to a hundredth of an inch, enough for a few slick spots on bridges.
Late night and early morning wind chills will range from around zero near the Arkansas border to the -10 to -15 range along and north of the Highway 60 corridor. High temperatures will struggle to warm out of the single digits across central Missouri with most of southern Missouri only warming into the lower to middle teens.
Patchy freezing drizzle has been reported across portions of nern OK and wrn AR but this activity has been light enough and intermittent enough to not cause any impacts in our forecast area. Although we still expected some drying in the low levels across nern OK/nwrn AR this afternoon, this trend has been slower than expected. Thus, we have adjusted forecast accordingly with clouds slower to diminish, and freezing drizzle/ drizzle to continue into late afternoon.
259 PM MST Sat Dec 30 2017 Strong winds continue to blast across the high mountains, with peak gusts over the highest peaks reaching 80+ mph this afternoon. We have increased snow amounts in the high country to 1-4", and increased PoPs across the plains.
We are expecting deteriorating conditions this evening and overnight with another batch of freezing drizzle at the surface.
Even though very little snow is expected to fall, road surface temperatures will be cold enough to allow snow to accumulate in isolated instances, particularly on untreated surfaces and bridges and overpasses.
The first will be the potential for freezing drizzle mainly this evening and especially overnight. It appears the main precipitation type will be freezing drizzle with a possible change to snow by early Sunday morning.
As the system passes by come Sunday morning look for the heart of the cold arctic high pressure to make a move south into the area. Strong arctic high pressure will settle into the area later Sunday night. Even as north winds ease off as the high center approaches a north wind of around 5 to 7 mph still produces wind chills in the 20 to nearly 30 below range most spots so have gone with a wind chill warning everywhere tomorrow night.
High pressure aloft will shift further south and flatten today.
Temperatures are ranging from the mid 60s out east to the low 70s in the Delta.
Harvey has picked up speed and this trend will continue as mid and upper level Subtropical ridging begins to build in from the west.
602 AM EDT Wed Aug 30 2017 A narrow north to south ridge of high pressure will slide east across Pennsylvania today. A strong cold front will likely push through the region on Thursday accompanied by a few afternoon or evening showers and thunderstorms.
A cold front will bring a band of clouds and cooler air through the area later tonight into Thursday.
Daytime temperatures return closer to normal, with highs in the lower 90s coast to near 100 degrees across the Rio Grande Plains. Drier air and mostly clear skies overnight, along with light winds will allow for temperatures tonight to be a bit cooler than normal, with lows in the lower 70s across the region.
556 AM EDT Wed Aug 30 2017 High pressure will remain over the region today while low pressure tracks well south of Maine.
A relative dry slot should contribute to a zone of enhanced daytime heating and instability with temperatures reaching the low to mid 80s across most of the forecast area.
252 AM EDT Wed Aug 30 2017 High pressure will keep the weather dry today. A cold front will pass Thursday bringing a chance for showers and a few thunderstorms, followed by more cool and dry weather to end the week. A ridge of high pressure over southeast Ontario will move southeast into the area today bringing drier air and mostly sunny skies. After lows from 45 to the low 50s temperatures rebound to the low and mid 70s this afternoon. Nondiurnal trend with clouds and showers moving in from the northwest ahead a cold front. A cold front will drop through the region on Thursday primarily between 09Z-18Z.
Upper troughing over the Midwest these next couple of days will act as a magnet, slowly drawing up the remnants of Tropical Storm Harvey into the Ohio Valley by the end of the work week. Thursday evening, the model consensus places the center of Harvey's low pressure area near the AR/TN/MS border. This band would come as the upper low merges in with the trough over our area. 5-2" range with this band, but will be higher still closer to the low.
A weak cold front currently extending from Lake Superior westward into the Dakotas will slowly sink southward tonight, reaching the I-80 corridor toward dawn.
Temperatures were in the low to mid 60s across most of the CWA with our far southeast CWA likely closer to 70 degrees. Dewpoints across the area were in the low 60s. Overall upper level pattern has not changed much from last night, with an upper level ridge in the western U. and northwest flow across the plains digging into a trough from the mid MS valley into the northeast U. For today and tonight, slightly warmer conditions are expected than yesterday, but we will still remain below normal for this time of year. Highs are expected in the low 80s with lows back into the low to mid 60s.
An upper ridge over Florida will extend into the region today while ridging also remains in place at the surface. Tropical Storm Harvey will slowly lift northeastward from the coast of Louisiana into the lower Mississippi Valley. A warm front located over southern Georgia will slowly lift north today. Precipitable water values will increase with the highest values in the CSRA, around 2 inches. Temperatures may be cooler in the CSRA due to higher chance rain/in situ wedge. The center of weak high pressure will have moved east of the cwa by early tonight. A warm front will still be located well south of the forecast area overnight, and will slowly push northward during the day Thursday. Better rain chances should occur Thursday into Thursday night as the warm front nears and the remnants of TS Harvey moved northwest of the cwa.
/Issued 815 PM EDT Tue Aug 29 2017/ Fcst period will be characterized by a weakening ridge of high pressure as we say goodbye to the Fall-like cool/dry conditions between Harvey to the SW and an exiting low off the Carolina coast. With the lingering wedge of high pressure in the NE, we should stay primarily stable, though some southern and western areas could see enough instability realized to warrant a slight to low end chance of thunderstorms - only general in nature and no strong/severe threats this far away from the main Harvey circulation/helicity maximum.
The high pressure over the western Great Lakes will continue to shift south and east overnight. A cool front will drop south through the Northland later this evening, making its way to the Highway 2 corridor in northeast Minnesota by dawn. The low wind speeds, mostly clear skies, and high relatively humidity overnight means another night of potential fog. Breezy northeast flow will develop over and downwind of Lake Superior in the wake of the front, keeping areas from the Twin Ports to northern Wisconsin near the Lake cooler than inland areas. High pressure will build across the Northland behind the departing cool from Wednesday evening ushering in a period of quiet weather for the remainder of the work week. Mid-level ridging will build across the Northern Plains and Canadian Prairies.
519 AM EDT Wed Aug 30 2017 Weak high pressure over the region today and tonight will shift off the coast Thursday.
Still expecting most of the activity to be over the Front Range and east slopes, and possibly extending onto the Cheyenne Ridge and Palmer Divide late in the day. the ridge over the Four Corners region will weaken and flatten early Thursday as the flow aloft becomes westerly in response to a weak disturbance passing across WY and northern CO. At the surface, a weak lee side trough will be around on Thursday.
An upper level high continues to sit over the desert southwest troughing out east. On the northern periphery of the high, it appears that the prevailing flow is starting to make some progress in trying to break it down (expected as we transition to autumn).
Strong mid/upper level ridge dominates the western half of the country with a complex trough/split flow aloft over the eastern portion of the country with what is left of Harvey on the southern end of this. Models started out well with the low level thermal field. Models are a little weaker with the mid level ridging.
247 AM CDT Wed Aug 30 2017 Early morning satellite imagery together with GFS 500 mb heights and winds showed an upper level wave across central Canada, with clouds and precip along a cold front which extended into northern Minnesota.
/issued 354 PM EDT Tue Aug 29 2017/ TONIGHT: We've settled more firmly back into a typical summertime pattern across South Florida as the western Atlantic ridge axis begins to work its way north and west from its position over the Florida Straits. REMAINDER OF THE WEEK: Mid/upper level ridge will continue to build westward from the Atlantic through the remainder of the week.
524 AM EDT Wed Aug 30 2017 High pressure will remain over the region today while low pressure tracks well south of Maine.
1138 PM MDT Tue Aug 29 2017 A 594dm high pressure center remains centered over southwest Utah early this afternoon with northerly flow aloft over the area. The upper ridge is forecast to slowly move east tomorrow as an upper level trough and pacific cold front move onto the west coast. A few mid and upper level clouds will spill over the ridge and into the area from the north, especially Wednesday.
Elevated moisture and instability continues to interact with the incoming trough resulting in some sprinkles across Tuolumne County early this morning, otherwise skies are clear across the region. Temperatures are cooler compared to 24 hours ago through much of the Central Valley due to the return of onshore flow, while readings are still mild at the north end of the Sacramento Valley and over the mountains. Showers chances will continue in the Sierra to the south of Lake Tahoe this morning before the moisture and instability is shunted eastward in the afternoon by the incoming trough. While still hot, temperatures will be a bit cooler today due to the combination of synoptic cooling associated with the trough and continued onshore flow. Hotter weather returns Thursday as strong ridging from the eastern Pacific begins to build into NorCal.
SHORT TERM (Now through Thursday): No significant changes to the short term forecast this morning as Deep South Texas remains between to large areas of high pressure, one across the Western CONUS and the other over the SE U.
This precip is in response to a diffuse surface boundary trailing behind a closed upper low moving slowly across the Great Lakes. A moisture-starved wave in the NW flow swings through on Wednesday, but by Wednesday night all eyes turn to the south as the remnant low of Harvey starts to lift through the lower Mississippi Valley.
The arrival of a cold front Wednesday night should bring cleaner air into the Inland Northwest by Thursday. Locally breezy conditions will accompany the cold front late in the day Wednesday and into Thursday.
609 AM EDT Wed Aug 30 2017 A ridge of high pressure will remain over the region today while an ocean storm passes well to our south. A cold front will move southeast through the region Thursday, and provide a chance of showers, especially in the mountains.
Thereafter sct-bkn clouds at about 4500 feet into this evening with lower cigs again overnight tonight as cold front works through area and N/NNE flow ensues. Dense fog gradually dissipating/mixing out during the morning hours, and with enough sunshine anticipated this afternoon, still expecting maxes near 80 degrees ahead of a cold front which will be dropping south through northern Lower Michigan. Seasonably strong high pressure (1026-1028 MB) becoming firmly established over the northern great Lakes Thursday night, and temps should be able to drop into the 40s even with winds failing to fully decouple.
Low level onshore flow and a weak frontal system will bring somewhat cooler weather to Western Washington today and Thursday, with night and morning cloud cover and some afternoon sunshine.