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STORM MODE THREAD- January 22-23 Mid Atlantic Storm Thread #4 - No Banter

stormtracker

By stormtracker,
in Mid Atlantic

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yoda

yoda

Posted
Posted

822
FXUS61 KLWX 220900
AFDLWX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC
400 AM EST FRI JAN 22 2016

.NEAR TERM /UNTIL 6 PM THIS EVENING/...A MAJOR WINTER STORM IS EXPECTED
TO IMPACT THE MID-ATLANTIC TODAY AND CONTINUE THROUGH SATURDAY
NIGHT. WINTER STORM AND BLIZZARD WARNINGS ARE IN EFFECT.

A DEEPENING TROUGH IS AIDING IN CYCLOGENESIS ACROSS ALABAMA AS A
1004MB SFC LOW CONTINUES TO INTENSIFY. WATER VAPOR AND REGIONAL
RADAR SHOW EXCESSIVE PRECIPITATION ACROSS PORTIONS OF THE TN VALLEY
AND SE US WITH STRONG TO SEVERE STORMS MOVING INTO GA/FL PANHANDLE.
THE NRN EDGE OF PRECIPITATION HAS REACHED SW VA/W NC THIS MORNING
AND IS MOVING SLIGHTLY FASTER THAN PREVIOUS MODEL GUIDANCE WAS
SHOWING. HI-RES MODEL GUIDANCE INCLUDING THE HRRR...NSSL WRF AND NAM
FIRE WX NEST HAVE CAUGHT UP WITH THIS TREND AND SNOW IS NOW EXPECTED
TO MOVE INTO THE REGION 1-2 HOURS FASTER THAN PREV THOUGHT
TODAY...REACHING THE SW CORNER OF THE CWA BY 7AM...NOVA/DC BY 1PM
AND BALTIMORE BY 3PM. SATURATION WILL INCREASE THIS MORNING AS THE
SYSTEM MOVES NORTHWARD. LOW-LEVEL DRY AIR WILL KEEP SNOW LIGHT AT
THE START BUT AFTER 1-3 HRS...SNOW IS EXPECTED TO BECOME MODERATE.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH SATURDAY NIGHT/...
BY 00Z SATURDAY/FRIDAY EVENING THE SFC LOW WILL TRANSITION TO THE
COAST AND RAPIDLY INTENSIFY. THE BAROCLINC ZONE ON THE NORTH SIDE OF
THE SFC LOW WILL BECOME STRONGER TONIGHT WITH A 50-70KT EASTERLY LLJ
ACROSS THE MID-ATLANTIC REGION. WINDS ARE GOING TO RAMP UP CAUSING
CONDTIONS TO WORSEN OVERNIGHT...BLOWING SNOW WILL CAUSE NEAR ZERO
VISBILITIES AND DRIFTING SNOW. LAPSE RATES ARE ALSO EXPECTED TO
INCREASE TONIGHT INTO SATURDAY AND THUNDERSTORMS ARE POSSIBLE MAINLY
EAST OF THE BLUE RIDGE. THIS WILL CAUSE SNOWFALL RATES TO INCREASE
TO 2+INCHES AN HOUR ACROSS THE REGION. AS THE COASTAL LOW MOVES
CLOSER TO THE REGION TONIGHT INTO SATURDAY...WARM AIR INTRUSION MAY
MOVE INTO SOUTHERN MARYLAND WITH SLEET MIXING INTO THIS REGION.
DEPENDING ON THE TRACK SOME OF THE MIXED PTYPE MIGHT MOVE IN AS FAR
WEST AS I-95 SATURDAY. THERE IS LOW CONFIDENCE FOR SNOWFALL TOTALS
ACROSS SOUTHERN MARYLAND ESPECIALLY ST MARYS COUNTY WHERE THERE
COULD BE A VERY TIGHT GRADIENT BETWEEN A FOOT OF SNOW AND A FEW
INCHES. AT THIS TIME...DUE TO THE INTENSITY AND CURRENT FORECAST
TRACK OF THE SFC LOW...SNOW IS EXPECTED TO OUTPLAY MIXED PTYPE.

WINDS WILL BE MAXIMIZED LATE TONIGHT AND INTO SATURDAY AS THE SFC
LOW APPROACHES THE CHESAPEAKE BAY. NE WINDS 30-40 MPH WITH GUSTS UP
TO 65 MPH ARE EXPECTED ALONG AND EAST OF I-95. FURTHER WEST...WINDS
WILL TAPER OFF BUT STILL BE STRONG.

THE SFC LOW WILL MOVE OFF THE DELMARVA COAST BY SATURDAY MORNING.
SNOW WILL CONTINUE ACROSS THE AREA THROUGH THE MORNING. ANY MIXED
PTYPE ACROSS COASTAL REGIONS WILL LIKELY CHANGE BACK TO SNOW BY
SATURDAY EVENING AS COLDER AIR MOVES INTO THE REGION.

THERE WAS NO CHANGE TO STORM TOTAL SNOWFALL TOTALS OVERNIGHT.
CONSISTENCY IS STILL PRESENT IN MODEL GUIDANCE WITH CLOSE TO TWO
FEET OF SNOW EXPECTED ACROSS MOST OF THE REGION WITH 1-2 FEET
EXPECTED ACROSS THE POTOMAC HIGHLANDS AND SOUTHERN MARYLAND. DUE
TO ELEVATION...2-3 FEET OF SNOW IS EXPECTED ACROSS THE BLUE RIDGE.
WITH THAT BEING SAID...THERE IS STILL A SPREAD OF ENSEMBLE MEMBERS
MAINLY SHOWING HIGHER SNOWFALL TOTALS ACROSS THE REGION. THESE
SEEMS TO BE IN RESPONSE TO HIGHER QPF. UPDATES TO THE FORECAST ARE
ALWAYS NECESSARY AND WILL BE DONE THROUGHOUT THE EVENT.

&&

.LONG TERM /SUNDAY THROUGH THURSDAY/...MAJOR STORM SHOULD BE OVER
BY 12Z SUN IF NOT SOONER BUT NOT AFTER DUMPING 20 TO 30 INCHES OF
SNOW OVER A LARGE AREA. IMPROVING WEATHER SUN THROUGH MON AS HIGH
PRES BUILDS IN ALTHOUGH STILL BREEZY ON SUN

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wxdude64

wxdude64

Posted
Posted

to accomplish the amts of snow forecasted you would have to have 3-4 in snowfall per hr for many hrs, that's whiteout conditions.

That is funny, 'cuz NWS Blacksburg sent out emails to spotters around midnight asking for help in amounts and start times and they mentioned 4 in rates possible, I'd think from the models that up there would be even higher rates than here.......

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Random Chaos

Random Chaos

Posted
Posted

Looking at the 6z RGEM and NAM-4K on Tropical Tidbits (with their fixed 10:1 ratio) and looks to be 3.5 to 4' jackpots there too, in line with the insane GFS. I recall Sterling indicated a 12:1 average ratio yesterday, which would bring their totals right to what GFS is showing.

 

All three models (GFS, RGEM, NAM-4K) now show the surface low retrograding over the mouth of the Chesapeake Bay.

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ohwxguy

ohwxguy

Posted
Posted

This 06z update shows pretty clearly the presence of a dry slot that wasn't shown in the 00z version. And while is shows a very strong 2nd round moving in, it also makes it clear how reliant DC is on deformation banding to really produce for HECT or else the overall snowfall projection is in jeopardy. To go from no indication of a dry slot for DC with the 00z data to now having a dry slot with the 06z data, I'll be anxious to see the 12z update.

DCA is around 2.4" QPF all snow on 06z RGEM:

attachicon.gifR9_RN_S9_SN_G9_PE_Z9_FR_METE_0000_Washington.png

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Random Chaos

Random Chaos

Posted
Posted

I have a serious question... Would there be a threat of storm surge inside the eastern tributaries of the bay? I just heard the marine forcast on the news and it sounds like several hours of prolonged easterly winds.

 

CBOFS is not predicting that; wind direction prevents water backing up into the bay:

 

http://tidesandcurrents.noaa.gov/ofs/ofs_animation.shtml?ofsregion=cb&subdomain=0&model_type=wl_forecast

 

For instance, Annapolis:

 

http://tidesandcurrents.noaa.gov/ofs/ofs_station.shtml?stname=Annapolis&ofs=cb&stnid=8575512&subdomain=0

 

And Baltimore:

 

http://tidesandcurrents.noaa.gov/ofs/ofs_station.shtml?stname=Baltimore&ofs=cb&stnid=8574680&subdomain=0

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GirlForAllSeasons

GirlForAllSeasons

Posted
Posted

Thanks! Ocmd has a period tomorrow morning where they go over five feet. Not sure if that is depelarture from the normal high tide or if that is just cumulative... But either way it could get serious down there nonetheless.

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SomeguyfromTakomaPark

SomeguyfromTakomaPark

Posted
Posted

From the WPC discussion:

 

WPC AMOUNTS UTILIZED WPC QPF WITH A THERMAL BLEND OF THE GFS AND
ECMWF...DISCOUNTING THE NAM AND SREF ESPECIALLY ACROSS THE
NORTHEAST ON DAY 2 AS NORTHERLY OUTLIERS. OVERALL FORECAST
CONFIDENCE WAS ABOVE AVERAGE...BOLSTERED BY FAIRLY GOOD AGREEMENT
BETWEEN THE GFS/ECMWF. CONFIDENCE WAS TEMPERED SOME BY THE 00Z
ECMWF...WHICH IS INDICATING A SIGNIFICANT DRY SLOT WHICH WOULD
HAMPER AMOUNTS ACROSS PORTIONS OF THE MID ATLANTIC ON SATURDAY.
IN ADDITION...STRONG FRONTOGENESIS IS EXPECTED TO PRODUCE A TIGHT
NORTHERN GRADIENT ACROSS THE NORTHERN MID ATLANTIC INTO SOUTHERN
NEW ENGLAND. WHILE THE NAM AND A NUMBER OF SREF MEMBERS ARE
LIKELY TOO FAR TO THE NORTH...A SLIGHT SHIFT IN THE LOW TRACK MAY
REQUIRE ADJUSTING THE NORTHERN EXTENT OF ACCUMULATING SNOWS.

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SomeguyfromTakomaPark

SomeguyfromTakomaPark

Posted
Posted

I am no expert but that sounds bad. It sounds to me like they are saying that it's gonna stop early here in the Washington DC area and than snow harder north of us. Geez!!!

 

They are saying their confidence of the 2 foot plus totals is tempered for the areas that might dryslot (which includes DC), they aren't saying what is or isn't going to happen definitively.  I think we'll be more confident about the placement of the dryslot when the 12z suite is complete and hopefully it'll look different than what the euro showed last night.

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