Thursday, January 17, 2019

2 comments:
I N F I N I T Y  W I N T E R ?
Three weather words for the weekend: 
Monsoon, Whiteout, Glacier. See below for updates.

FOR MARVEL FANS, EVEN THAT VIBRANIUM-INFUSED SHIELD MAY NOT BE ENOUGH PROTECTION FROM THE WICKED RAIN, SNOW & COLD THAT'S COMING.


Update as of 5:30 AM ET Thu 1/17

  • THU PM - FRI AM: For most areas from the DC metro to Baltimore metro & the PA line- Light accumulating snow is expected late this afternoon into the PM commute. Snow may fall at a moderate pace for several hours, continue overnight and being tapering toward daybreak. At least 1.0" of snow is likely, and with recent snowpack in place, a chilled surface may reduce loss of the first 1/2", providing for many areas to reach 2" or slightly more.  Below is Mount. Airy, MD in Carroll County as representative location for the region, to indicate timing and general amounts.


  • SATURDAY ( THE MONSOON) For most of the region, precip begins as rain and snow mixed or a period of snow, then turns to mostly rain as temperatures rise well above 32 F ahead of an Arctic front. Late Saturday into Sunday, potentially torrential rain is possible during embedded cells. Up to 1.5 inches of liquid is possible in this period.
  • SUNDAY (THE WHITEOUT?) As the Arctic front crosses the area, temperatures near 40 F around Noon will rapidly drop to the low teens before midnight. Rain in the morning will switch back to snow by 2 PM and could become heavy at times, producing even whiteout or blizzard-like conditions. Have your umbrella, popcorn and water proof phone ready for the weathertainment to come. THEN, all that leftover water seeping everywhere across roads, parking lots, sidewalks and your front step? It will FLASH FREEZE and be a solid block of ice before daybreak. This sets the stage for...
  • MONDAY (THE GLACIER!) With temps between 5-10 F, and no pre-treatment on roads, and all that water having frozen, it's a good thing Monday is a holiday. We think most area roads will be a complete sheet of ice. The safest thing to do is stay home if you don't have to work. With temperatures holding below 20 F until late Tuesday, we wonder how road & grounds crews will prepare buses, lots and sidewalks given that salt treatment generally is much less effective at very low temperatures.
  • BY THEN, YOU'LL HAVE a Captain America or Wonder Woman-level of fortitude to conquer the Infinity Winter that is coming next... (Click image for a larger version)




And if you're a snow plow operator, you'll be saying this a lot the next 2 weeks.

Tuesday, January 15, 2019

6 comments:
"Ohhh, it's Saturday night..."
- lyrics from Say Amen (Saturday Night) by Panic! at the Disco
  • Ready for real winter? The 1/12-13 storm was just the starting point of what will become a Big Kahuna-packed two weeks or more of multiple winter weather & severe cold threats for much of the northern & eastern United States.
  • This Thursday's spritz of light snow/wintry mix in the overnight hours to Friday morning is akin to a "cover band" before the featured singer (the much bigger storm) takes the mic this coming Saturday night. Below is the NWS hourly chart for Eldersburg, MD as a representative location on timing in the region for when light  accumulating snow and sleet is expected to occur:

  • The big reveal: At this point in winter, it appears the Mid-Atlantic is entering an "every 3 days" pattern  of storm events, with Saturdays the center stage for each opening night of the next big snow show. Below, early probabilities for this weekend of possible winter wickedness are already at 30-50% across a massive swath of the northern U.S.  
This map is the Day 7 Winter Weather Outlook from the NOAA Weather Prediction Center. It shows that long range expectations are already increasing for this next system to exceed 0.25" of frozen precipitation through next Sunday morning.




So it might be a good idea to be praying for the wicked this weekend, because what's coming will need some divine intervention so there's no panic at the winter weather disco.  

Then again, once you see the show for yourself, you'll understand why we're concerned. Unless you have fond memories of January 1994.  -Forecaster Foot 

Sunday, January 13, 2019

3 comments:
How Much Longer & What About Monday?
UPDATE AS OF 10:45 AM ET SUN 1/13

  • NORTH OF THE PA LINE, LIGHT TO MODERATE SNOW CONTINUES THROUGH 7 PM BEFORE TAPERING TOWARD MIDNIGHT, WITH AN ADDITIONAL 2" 
  • FOR NORTHERN MD COUNTIES TO I-70/BALTIMORE CITY LINEMODERATE SNOW CONTINUES THROUGH 5 PM, THEN BECOMING LIGHTER AT TIMES AFTER SUNDOWN, WITH AN ADDITIONAL 4-5" AND STORM TOTALS OF 5-10" LIKELY.
  • FROM BALTIMORE CITY SOUTH TO DC METRO INCL. MONTGOMERY, ANNE ARUNDEL, PRINCE GEORGES, MODERATE SNOW TO CONTINUE THROUGH 10 AM, THEN BECOME HEAVY THROUGH 4 PM, WITH AN ADDITIONAL 4-6" PROBABLE IN MOST LOCATIONS, WITH 10" OR MORE LIKELY. TAPERING TO LIGHT SNOW AFTER 10 PM.
  • FOR THE EASTERN SHORE, HEAVY SNOW WILL CONTINUE AT A STEADY PAVE THROUGH NIGHTFALL, WITH WIDESPREAD 4-8" TOTALS FOR ALL AREAS NORTH OF OCEAN CITY. AREAS NEAREST THE BAY MAY EXCEED 8" BY 6 PM TODAY, WITH ACCUMULATING SNOW ENDING BY MIDNIGHT.
  • FOR ALL AREAS: SOME DECREASE TO LIGHT AND MODERATE SNOW INTENSITY EXPECTED FROM AROUND 6 PM, WITH SNOW STARTING TO EXIT THE REGION AROUND 10 PM. ACCUMULATING SNOW SHOULD END BY 12 AM, AND WITH TEMPERATURES REMAINING BELOW 32 MOST OF THE DAY, REFREEZING WILL QUICKLY DEVELOP BY SUNDOWN WITH LOWS IN MID 20S REGION-WIDE. 
  • ABOUT MONDAY: hWell, considering that Winter Storm Warnings were just extended to 12 AM Monday for most locations-- we think tomorrow is largely done for most schools and colleges. The NWS hourly chart above is from Parkville, MD a representative location for the region to illustrate that scattered light snow is still possible in some areas until at least 11 PM tonight. An upper level disturbance is expected to pass through in the final hours, and this would briefly enhance any last snow showers to produce up to 1/2" extra in the 8-11 PM period. This indicates icy conditions should be expected for the AM commute beyond major highways & beltways, specifically in backstreet roads, secondaries, bridges, overpasses and off ramps.
  • PLOWS & LOTS: Many plow operators may need to make three full passes for removal due to the extended duration of this event. If a late stage accumulation occurs, they would have to come back for a 4th pass. Crews working on school & bus lots will have to decide if there is adequate time to make one full cleanup once snow ends this evening, or should they start early knowing a second full pass will be needed before Monday morning?
  • SHORT RANGE SIMULATED RADAR: Snow exiting the 95 corridor around 11 PM as shown below in the High Resolution Rapid Refresh (HRRR) model.

Saturday, January 12, 2019

IF IT'S MEANT TO BE, IT'LL BE

15 comments:
A Weekend of "White in the Winter Night" 

7:15 PM ET SAT 1/12 UPDATE








  • WINTER STORM WARNINGS RAISED FOR MOST OF BALTIMORE-WASHINGTON METRO AREA FROM SATURDAY LATE AFTERNOON THROUGH 6PM SUNDAY FOR 4-8" OR MORE OF SNOW. 
  • DC METRO AND NORTHERN VIRGINIA MAY EXCEED 8" IN AREAS WHERE HEAVIEST SNOW OCCURS EARLY SUNDAY MORNING.
  • SHORT RANGE MODELS SHOW INCREASING POTENTIAL FOR A LATE SUNDAY PM SNOW SQUALL TO CROSS THE I-66 CORRIDOR AREA, PRODUCING AN ADDITIONAL 1/2-1"
  • BESIDES, if you're a Powderhound, isn't this is what we live for, right? Expecting snow and then finding out that your area has been UPGRADED to a WARNING! Golden.
  • SPECIAL NOTE ABOUT THE FORMER INSIDER APP: The Insider App program, operational during the 2015-2017 period is unfortunately no longer available. We do not yet have a projection on if or when this will resume, but are grateful for the generous support and readership many of you devoted to app in those years.
SNOWFALL TIMING & AMOUNTS

  • SATURDAY: Light snow developing in DC metro area/northern VA between 2-3 PM, in Baltimore metro from 3-4 PM, northern MD/PA line by 5 PM. Intensity will pickup into the evening as the eastward moving energy is transferred to a developing coastal low off North Carolina.
  • SATURDAY PM  - SUNDAY AM : Snow intensity region-wide for all areas will increase toward nightfall and continue overnight. This includes a region from the DC I-66 corridor north to the PA I-76 turnpike and east to the Chesapeake Bay & the Eastern shore of MD/DE. Up to 3" is probable by daybreak Sunday for these areas. Sunday AM activities including worship services likely to be impacted. Areas south of I-70 may receive 4" or more where heavier bands develop.
  • SUNDAY PM - MONDAY AM : Snow begins tapering south to north, ending in DC metro by Sunday noon, Baltimore metro region in mid afternoon,and southern PA/Eastern shore by sundown. With sub 30 F temperatures overnight Sunday and powdery snow composition refreezing on untreated surfaces, it is likely that travel delays and some disruptions will occur for the Monday AM commute. For schools, if a second round of snow occurs after grounds crews have cleared lots and prepared buses, Monday may be a challenging situation depending on one's location.
  • LET'S SEE WHERE THIS THING GOES... Short range computer models guidance continues to indicate that higher totals are possible, due either to moisture enhancement from the eventual coastal system, higher snowfall ratios due to cold air, or a northern creep of higher moisture levels. Any of these would result in surprise increases of 1-2" in snowfall totals in the final 6 hours of this event.

EARLIER MAPS & UPDATES BELOW

  • REPRESENTATIVE COMPUTER MODEL GUIDANCE FOR SNOWFALL SAT PM - SUN