April 22-23, GL/MidAtl/NE/ NorEaster OBS, Post Last Minute Forecast and OBS Options

[WEATHERFAN100]

Pretty impressive yellow (35 DBZ) line setting up across Philadelphia into northern Maryland. Also lots of yellow across New Jersey. Really starting to ramp up now.

http://radar.weather.gov/radar.php?rid=dox...111&loop=no

[LUCC]

For Philly, the storm won't ramp up til late afternoon through the evening.
Also, LUCC, Mercer is under the Flood Watch, for what it's worth, even though the graphic doesn't depict it.

http://weather.noaa.gov/cgi-bin/iwszone?Sites=:paz071

DEZ001-NJZ008>010-012-015-PAZ067>071-230800-
/O.CON.KPHI.FA.A.0001.000000T0000Z-120423T0800Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.
O/
NEW CASTLE-MORRIS-HUNTERDON-SOMERSET-MIDDLESEX-MERCER-CHESTER-
MONTGOMERY-BUCKS-DELAWARE-PHILADELPHIA-
INCLUDING THE CITIES OF...WILMINGTON...MORRISTOWN...FLEMINGTON...
SOMERVILLE...NEW BRUNSWICK...TRENTON...WEST CHESTER...
NORRISTOWN...DOYLESTOWN...MEDIA...PHILADELPHIA
333 PM EDT SUN APR 22 2012

FLOOD WATCH REMAINS IN EFFECT THROUGH LATE TONIGHT
THE FLOOD WATCH CONTINUES FOR
* PORTIONS OF NORTHERN DELAWARE...NEW JERSEY AND SOUTHEAST
PENNSYLVANIA...INCLUDING THE FOLLOWING AREAS...IN NORTHERN
DELAWARE...NEW CASTLE. IN NEW JERSEY...HUNTERDON...MERCER...
MIDDLESEX...MORRIS AND SOMERSET. IN SOUTHEAST PENNSYLVANIA...
BUCKS...CHESTER...DELAWARE...MONTGOMERY AND PHILADELPHIA.
* THROUGH LATE TONIGHT
* HEAVY RAIN IS EXPECTED FROM LATE THIS AFTERNOON TO THE EARLY
PORTION OF MONDAY MORNING. EVENT RAINFALL TOTALS OF 2 TO 3
INCHES ARE EXPECTED...WITH THE HIGHEST AMOUNTS ACROSS PORTIONS
OF NORTHERN NEW JERSEY. EVEN THOUGH WE HAVE BEEN VERY DRY
LATELY...THIS MUCH RAIN COULD RESULT IN FLOODING OF QUICK
RESPONDING STREAMS AND SMALL RIVERS...SUCH AS THOSE IN NORTHERN
DELAWARE AND SOUTHEAST PENNSYLVANIA. IN ADDITION...URBAN
FLOODING FLOODING IS POSSIBLE.
* AT THIS TIME...MAINSTEM RIVER FLOODING IS NOT EXPECTED.
PRECAUTIONARY/PREPAREDNESS ACTIONS...
A FLOOD WATCH MEANS THERE IS A POTENTIAL FOR FLOODING BASED ON
CURRENT FORECASTS.
YOU SHOULD MONITOR LATER FORECASTS AND BE ALERT FOR POSSIBLE
FLOOD WARNINGS. THOSE LIVING IN AREAS PRONE TO FLOODING SHOULD BE
PREPARED TO TAKE ACTION SHOULD FLOODING DEVELOP.
&&

Yeah I know, just funny as per the NOAA warning/watches that Mercer had none at that time.

[jdrenken]

This will be a forecast nightmare for quite a few WFO's. I believe the Buffalo WFO will be the only slam dunk regarding snowfall.

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BUFFALO NY
652 PM EDT SUN APR 22 2012

.SYNOPSIS...
A SIGNIFICANT EAST COAST STORM WILL SPREAD RAIN AND SNOW ACROSS THE
REGION TONIGHT AND MONDAY CONTINUING INTO TUESDAY. LATE SEASON SNOW
WILL ACCUMULATE ACROSS WESTERN NEW YORK AND THE HEAVY WET NATURE MAY
CAUSE DOWNED TREES AND POWER OUTAGES IN SOME AREAS TONIGHT THROUGH
TUESDAY. HEAVIEST SNOW IS EXPECTED ACROSS THE HIGHER TERRAIN OF
SOUTHERN TIER OF WESTERN NEW YORK. TEMPERATURES WILL MODERATE
THROUGH THE REST OF THE WEEK WITH ANOTHER CHANCE FOR RAIN LATE WEEK.

&&

.NEAR TERM /THROUGH MONDAY/...
REGIONAL RADARS SHOWING LEADING EDGE OF LARGE RAIN SHIELD PUSHING
NORTHWARD ACROSS EASTERN PENNSYLVANIA INTO SOUTHERN AND EASTERN NEW
YORK STATE AHEAD OF SURFACE LOW CENTERED ALONG THE CAROLINA COAST.
THIS PRECIPITATION SHIELD WILL CONTINUE TO SPREAD NORTHWEST
TONIGHT AS THE DEEPENING LOW LIFTS TO THE VICINITY OF SOUTHERN NEW
JERSEY BY 06Z...THEN TO NEAR NEW YORK CITY BY 12Z MONDAY MORNING.

HUGE FORECAST CHALLENGE WILL BE WITH THE PLACEMENT OF THE EXPECTED TIGHT
THERMAL GRADIENT. AS THE SURFACE LOW LIFTS NORTHWARD AND MOVES
CLOSER TO THE AREA...BACKING FLOW WILL ROTATE COLDER AIR INTO
WESTERN PORTIONS OF THE STATE...WITH THE 850 MB 0C DEGREE ISOTHERM
PUSHING EASTWARD ACROSS THE GENESEE VALLEY INTO THE WESTERN FINGER
LAKES. WE EXPECT RAIN TO CHANGE OVER TO SNOW ACROSS WESTERN SECTIONS
BY MIDNIGHT OR SHORTLY THEREAFTER AS THIS COLD AIR ARRIVES. HIGHER
ELEVATIONS WILL SEE A CHANGE OVER SOONER. WELLSVILLE IS ALREADY
REPORTING SNOWFALL IN ALLEGHENY COUNTY AND THE GRIDS HAVE BEEN
UPDATE TO ACCOUNT FOR THIS EARLY ONSET.

TEMPERATURES ALOFT WILL CONTINUE TO COOL MONDAY AS THE LOW SLOWLY
WORKS ACROSS EASTERN NEW YORK. NEARLY ALL MODEL SOLUTIONS SUGGESTING
THE PRIMARY DEFORMATION AXIS WILL SET UP ACROSS WESTERN NEW YORK
WITH THIS AREA THE MOST LIKELY AREA TO RECEIVE HEAVY SNOWFALL.
THERE IS LITTLE CHANGE TO EXPECTED SNOWFALL AMOUNTS WITH THE
HEAVIEST AMOUNTS ACROSS THE WESTERN SOUTHERN TIER...IN THE 7 TO 14
INCH RANGE WITH AMOUNTS TAPERING OFF CLOSER TO THE LAKE ONTARIO
SHORELINE AND THE LOWEST ELEVATIONS ALONG LAKE ERIE. WARNINGS AND
STATEMENTS ISSUED WILL PINPOINT THE MOST PROBABLE IMPACTS...WHICH
INCLUDE HEAVY SNOW AND WINDS.

IN ADDITION...A STRONG 50 TO 60 KNOT LOW LEVEL JET WILL DEVELOP
OVERNIGHT TONIGHT AND CONTINUE THROUGH A GOOD PART OF MONDAY. AN
INCREASING SURFACE PRESSURE GRADIENT WILL BRING STRONG WINDS TO
THE SOUTH SHORE LAKE ONTARIO COUNTIES. THESE AREAS WILL BE PLACE IN
A WIND ADVISORY TO COVER THE THREAT. A LAKESHORE FLOOD WARNING HAS
BEEN ISSUED FOR MONROE COUNTY FOR CONCERNS OF HIGH WAVE ACTION ALONG
THE NORTHEAST FACING SHORE LINE.

ALONG WITH THE HEAVY WET SNOW...THERE WILL BE THE POTENTIAL FOR SOME
THUNDERSNOW. LOCAL RESEARCH FROM THIS OFFICE HAS SHOWN THAT
FAVORABLE CONDITIONS FOR THUNDERSNOW INCLUDES A DEEP MIXED PHASE
CLOUD LAYER (>4K FT) AND A TALL ENOUGH CLOUD (GEN >10K FT) FOR ANY
GENERATED CHARGE TO SEPARATE. THESE CONDITIONS WILL CERTAINLY BE MET
AS THE MIXED PHASE CLOUD WILL BE ROUGHLY 10K FT DEEP WITH MODERATE
SYNOPTIC LIFT THROUGH A WEAKLY CAPPED MOIST ENVIRONMENT. THUNDERSNOW
IS MOST LIKELY EXPERIENCED WITHIN SINGLE BANDED LAKE SNOWS
(PARTICULARLY EARLY SEASON EVENTS)...AND IN DEFORMATION ZONES OF
MARGINALLY COLD SYNOPTIC STORMS WHERE MIXED PRECIPITATION IS COMMON.
THE PRESENCE OF GRAUPEL IS NEEDED TO ALLOW ELECTRIFICATION TO BEGIN
AND THUS THE NEED FOR THE DEEP MIXED PHASE CLOUD. THE CHANCE FOR
THUNDER HAS BEEN ADDED TO THE HEAVY SNOW AREAS.

[Laurel Highlands]

Light rain has moved into the area. current temp is 42

[jdrenken]

Well...time to bring back my old saying...

There will be winners with this forecast...and others...not so much.

[Fire/Rescue]

And the first snow pic goes to....Snowshoe Mountain, West Virginia.. Thanks to Henry M. for posting it.

[attachment=162196:snow43.jpg]

Edit: Link. http://www.highcountrywebcams.com/webcamer...owshoe-live.htm

Gotta love it, that's what 4,848 foot of elevation will do for ya

[albanyweather]

Here she goes! Bombing out!

[Burr@Work]

Been raining by me since about 1130 this morning and has been heavy for much of the afternoon. WE for sure need the rain however most roads by me have at least minor pounding already.

It's been raining in Princeton Junction since about 10:30 am. Slowly, slowly, slowly been building up. I have an analogy in mind, but it's not suitable for all audiences.

[Burr@Work]

Yeah I know, just funny as per the NOAA warning/watches that Mercer had none at that time.

Agreed. The map still didn't show it when I pulled down that writeup.

[jdrenken]

HRRR forecast from 15Z


Current...

Attached thumbnail(s)

 

[SyracuseSnow]

Agreed. The map still didn't show it when I pulled down that writeup.

Off topic, but the Wind Advisory takes precedent over the Flood Watch which is why Mercer shows up as a light brown. The counties to the NW don't have Wind Advisories in effect hence the Dark Green shading.

Anyways, fun storm to track and now watch unfold. Can't wait to see the total snow accums. from WNY south towards W. VA.

[SyracuseSnow]

Agreed. The map still didn't show it when I pulled down that writeup.

Off topic, but the Wind Advisory takes precedent over the Flood Watch which is why Mercer shows up as a light brown. The counties to the NW don't have Wind Advisories in effect hence the Dark Green shading.

Anyways, fun storm to track and now watch unfold. Can't wait to see the total snow accums. from WNY south towards W. VA.

[jdrenken]

It's been raining in Princeton Junction since about 10:30 am. Slowly, slowly, slowly been building up. I have an analogy in mind, but it's not suitable for all audiences.

[Undertakerson]

Here she goes! Bombing out!

http://weather.unisys.com/surface/sfc_con....inv=0&t=cur

Attached image(s)

 

[Burr@Work]

HRRR forecast from 15Z

Current...

Lil bit quicker, lil bit stronger. Difrent analogy now.

This post has been edited by Burr@Work: Apr 22 2012, 06:52 PM

[DiehardFF]

anyway to figure out how much rain has fell?

[Fire/Rescue]

What an amazing looking storm on the radar... easily the best looking since Irene IMO.

[attachment=162205:northeast_loop.gif]

Absolutely, quite photogenic

[Burr@Work]

anyway to figure out how much rain has fell?

This link purports to be the accumulation over the past 24 hours, so it would include the overnight event as well...


http://www.accuweather.com/en/us/pennsylvania/weather-radar-24hr

[Fire/Rescue]

anyway to figure out how much rain has fell?

Purchase a rain gauge

[Fire/Rescue]

anyway to figure out how much rain has fell?

Also here is another graphic that shows the amount of accumulated precipitation over a given period of time, a running (storm total) it's a NWS product from the "Weatherunderground" site.
Link

Attached image(s)