Maybe we were a bit hasty with that Last Snow headline in late March...
It seems that we have not one but TWO snow events coming at us... and that's just through Monday morning. Although some April snow is newsworthy, the real story will be the combo of wind and cold heading for us.
We were pushing 70 degrees around here on Thursday and Friday. We'll be in the 20s on Sunday, with places north of us diving into the teens.
We also want to tag in now to let you know that there is a chance of coastal flooding at the end of next week. We'll get to that in a second.
Why not let the National Weather Service explain? They just published a detailed forecast for the whole active weather period. They use ALL CAPS, so it is obviously important stuff of which they speak:
RAIN TODAY WITH THE POSSIBILITY OF ISOLATED THUNDERSTORMS ACROSS
THE INTERIOR. INTENSE STORM SYSTEM EARLY SUNDAY MORNING. BURST OF
ACCUMULATING SNOW LIKELY. HURRICANE FORCE WINDS POSSIBLE. THEN AN
UNSEASONABLY COLD AIRMASS OVERSPREADS THE REGION SUNDAY AFTERNOON
AND NIGHT WITH BLUSTERY NORTHWEST WINDS. ANOTHER LOW PRESSURE
TRACKS OVER OR NEAR THE SOUTH COAST OF NEW ENGLAND
MONDAY...BRINGING THE RISK FOR ANOTHER ROUND OF ACCUMULATING SNOW
TO THE AREA. DRYING TREND TUE BUT REMAINING UNSEASONABLY COLD.
MODERATING TEMPERATURES MID TO LATE NEXT WEEK BUT ALSO THE RISK OF
WET WEATHER.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
7 AM UPDATE ...
NOT MUCH CHANGE FROM PREVIOUS FORECAST. RAIN SHIELD /MAINLY LIGHT/
CONTINUES TO OVERSPREAD RI AND EASTERN MA...WITH LITTLE IF ANY
RAIN NORTHWEST OF BOSTON TO PROVIDENCE CORRIDOR. FOR WHAT IT/S
WORTH THE 06Z NAM AND GFS BOTH TRENDED HEAVIER WITH RAINFALL LATER
THIS MORNING AND EARLY AFTERNOON ACROSS RI AND EASTERN MA. LOW
CONFIDENCE ON THIS SCENARIO WILL CONTINUE TO LEAN TOWARD LIGHT TO
PERHAPS MODERATE RAIN AT TIMES...HEAVIEST RI AND EASTERN MA WITH
LIGHTER RAIN ACROSS CT AND WESTERN-CENTRAL MA.
ONLY CHANGE TO THE FORECAST WAS TO LOWER HOURLY TEMPS A BIT AS
RAIN HAS LOWERED TEMPS CLOSER TO THEIR WET BULB VALUES. OTHERWISE
PREVIOUS FORECAST ON TRACK. EARLIER DISCUSSION BELOW.
===================================================================
INITIAL LIGHT TO MODERATE RAINFALL EVENT FOLLOWED UP BY A SWEEPING
COLD FRONT AND SOME CONVECTIVE SHOWERS.
SO WITH THE FIRST SYSTEM...WAVE LOW DEVELOPS ALONG THE STALLED
FRONTAL BOUNDARY OFFSHORE PARENT WITH STOUT MID LEVEL ENERGY AND
FORCING THROUGH THE OVERALL BROAD CYCLONIC TROUGH. GREATEST POP
CHANCES AND RAINFALL S AND E CLOSER TO THE SKIRTING WAVE LOW. MUCH
OF THE ACTIVITY EARLY MORNING INTO MIDDAY.
THEN SECONDLY...ATTENTION TURNS N/W WITH THE FIRST IN A SERIES OF
LOW PRESSURE CENTERS THAT BEGIN THE PROCESS OF DRAGGING COLDER AIR
ACROSS OUR REGION. IN TANDEM WITH A SWEEPING COLD FRONT WILL SEE THE
BOUNDARY LAYER COOL AND BECOME UNSTABLE UP TO H6. IF THE 24-HR HRRR
IS CORRECT...LOOKING AT CONVECTIVE SHOWER DEVELOPMENT AHEAD OF THE
FRONT ESPECIALLY ACROSS THE N/W/CENTRAL INTERIOR. STRONG LOW-MID
LEVEL FORCING TO THE TOP OF THE LAYER AROUND -20C COULD RESULT IN
GRAUPEL / SMALL HAIL WITH THESE SHOWERS ALONG WITH LIGHTNING...AS
WELL AS 20-30 MPH GUSTS. THREATS EXACERBATED IF WE SEE CLEARING
BETWEEN THE S STREAM WAVE LOW AND N STREAM SWEEPING COLD FRONT. WITH
ANY THUNDER MENTIONED IN THE FORECAST WILL APPEND GUSTY WINDS AND
SMALL HAIL. THREATS SWEEPING NW TO SE DURING THE LATER HALF OF THE
DAY INTO EVENING. INSTABILITY NOT AS ROBUST AS FRIDAY...SO THINKING
STORMS WILL NOT REACH WARNING CRITERIA.
OVERALL A MOSTLY CLOUDY AND COOL DAY IN ADDITION TO THE WET WEATHER.
HIGHS INTO THE 50S.
.SHORT TERM /6 PM THIS EVENING THROUGH 6 PM SUNDAY/...
TONIGHT INTO SUNDAY...
* STRONG TO DAMAGING WINDS NEAR HURRICANE FORCE POSSIBLE
* WIND ADVISORY / HIGH WIND WATCH POSTED
* CONVECTIVE SNOWS POSSIBLE WITH ACCUMULATIONS 1 TO 3 INCHES
* STORM FORCE WINDS ACROSS THE WATERS
SNOW BURST EARLY SUNDAY MORNING INTO MIDDAY ACCOMPANIED WITH STRONG
TO DAMAGING WINDS. WILL BE AN UNPRECEDENTED RARE EVENT INCORPORATING
RAPID CYCLOGENESIS...INTENSE LIFT...AND ACCUMULATING SNOWS AS WELL
AS THE LIKELIHOOD OF THUNDERSNOW. SHOULD SEE IMPACTS TAPER DOWNWARD
LATE AFTERNOON INTO SUNDAY EVENING. AFRAID MANY ARE GOING TO BE
CAUGHT OFF-GUARD WITH THE LATE SEASON SNOW. WILL HIT ON THE DETAILS
BELOW AS BEST AS POSSIBLE.
POTENT VORTEX OUT OF THE GREAT LAKES REGION CYCLONICALLY DIGGING S
OF NEW ENGLAND INVOKES INTENSE CYCLOGENESIS ALONG THE S-SHORELINE.
THIS WHILE DRAGGING CONSIDERABLY COLDER AIR ACROSS THE REGION WITH
H85 TEMPERATURES FALLING -10 TO -15C NEAR RECORD BREAKING PER LOCAL
SOUNDING CLIMATOLOGY. STRONG LOW TO MID FORCING ABOVE SURFACE INFLOW
AND BENT-BACK WARM FRONT WITH COLD AIR ADVECTION REARWARD RESULTING
IN THE ATMOSPHERIC COLUMN BECOMING SUPER-ADIABATIC / UNSTABLE UP TO
H6 BENEATH THE TROPOPAUSE FOLD. ENSEMBLE CLIMATOLOGICAL PERCENTILES
SHOWING THIS EVENT TO BE NEAR OR AT ALL-TIME HISTORICAL MINIMUMS...
IMPRESSIVELY ANOMALOUS.
TEMPERATURES / PRECIPITATION INTENSITY....CRITICAL WITH THIS EVENT
IS THE PRECIPITATION INTENSITY DETERMINING PRECIPITATION TYPE...AS
WELL AS 2M SURFACE TEMPERATURES. WILL DRIVE SUCH TEMPERATURES CLOSE
TO IF NOT AT THE WET-BULB DURING EXPECTED TIME-FRAME OF INTENSE
PRECIPITATION. INITIAL RAIN WHICH HAS INSTABILITY TO WORK WITH AS
THE COLUMN BEGINS TO COOL TO COULD YIELD GRAUPEL/SMALL HAIL WITH
ANY THUNDERSTORMS. BRIEF BEFORE CHANGING OVER QUICKLY TO A INTENSE
SNOWFALL.
SNOWFALL...ALONG SHORES EXPECT LITTLE IF ANY ACCUMULATION ADJACENT
TO WARMER WATERS. LOW ELEVATIONS EXPECTING SLUSHY ACCUMULATIONS ON
ELEVATED / GRASSY SURFACES WITH WET ROADWAYS. AND FINALLY N/W AND
ACROSS HIGH TERRAIN WITH COLDER TEMPERATURES THERE IS A GREATER
OPPORTUNITY AND MORE CONCERN FOR SNOW ACCUMULATION ON ALL SURFACES
WITH HIGHEST SNOWFALL AMOUNTS ATOP BERKSHIRES / WORCESTER HILLS.
SNOW EXPECTED TO OCCUR QUICKLY...IN A SHORT DURATION...ON THE ORDER
OF 1 TO 2 HOURS. STORM TOTAL ACCUMULATIONS 1 TO 3 INCHES AWAY FROM
THE COASTAL PLAINS.
THUNDERSNOW...PRECIPITATION SHOULD BE INTENSE CONSIDERING THE SUPER-
ADIABATIC / UNSTABLE LAPSE RATES. BENEATH THE POTENT VORTEX YIELDING
RAPID CYCLOGENESIS...LOOKING AT LIFT OF 50 MICROBARS PER SECOND IN
SNOW GROWTH REGIONS. DEFINITELY A SIGNAL FOR THUNDERSNOW. WILL PUT
AN ISOLATED MENTION INTO THE FORECAST. INTENSE ENOUGH...WOULD EXPECT
SNOW ACCUMULATION ON A MAJORITY OF SURFACES...EVEN AT THE LOWER
ELEVATIONS. COULD SEE 1 INCH PER HOUR SNOWFALL RATES. COMPLEX TO
FORECAST.
WINDS...INTENSE PRESSURE COUPLET YIELDING HURRICANE FORCE WINDS AT
H925 ACROSS NJ / DELMARVA EXTENDING ON UP ACROSS SE NEW ENGLAND AS
THE STORM EXITS LATE MORNING TO MIDDAY SUNDAY. WITH INCREDIBLY STEEP
LAPSE RATES...UNDOUBTEDLY A MAGNITUDE OF SUCH WINDS WILL MIX DOWN TO
THE SURFACE. 35 TO 55 MPH WINDS ACROSS INTERIOR NEW ENGLAND N TO S
WITH 50 TO 70 MPH WINDS ACROSS RHODE ISLAND AS WELL AS E/SE MASS.
HIGH CONFIDENCE FOR WIND ADVISORY CONDITIONS OVER ALL S NEW ENGLAND.
LOWER CONFIDENCE ON WHERE EXACTLY HIGH WIND WARNING CRITERIA WILL
BE MET. WENT WITH A WATCH OVER E/SE NEW ENGLAND.
.LONG TERM /SUNDAY NIGHT THROUGH FRIDAY/...
HIGHLIGHTS...
* VERY ACTIVE WEATHER PATTERN NEXT 7 DAYS
* TEMPERATURES - UNSEASONABLY COLD FOR EARLY APRIL SUNDAY THROUGH
WEDNESDAY...THEN MODERATING LATE NEXT WEEK
* PRECIPITATION - ACCUMULATING SNOW LIKELY MONDAY ALONG WITH OCEAN
EFFECT SNOW SHOWERS EASTERN MA TUE MORNING. OTHERWISE DRY TUE INTO
WED FOLLOWED BY WET WEATHER LATE NEXT WEEK
SUNDAY NIGHT ... MODELS HAVE SPED UP THE ARRIVAL OF THE NEXT SYSTEM
WITH SNOW POSSIBLY BEGINNING BEFORE SUNRISE MONDAY ACROSS WESTERN
PORTIONS OF CT AND MA. THUS TEMPS SUN NGT WILL NOT BE AS COLD AS
PREVIOUSLY THOUGHT. ALTH STILL UNSEASONABLY COLD. OTHERWISE DRY
WEATHER PREVAILS MUCH OF THE NIGHT WITH A VERY COLD AIRMASS IN
PLACE WITH TEMP ANOMALIES AT 925 AND 850 ABOUT -2 STANDARD
DEVIATIONS COLDER THAN CLIMO. THIS WILL RESULT IN TEMPS FALLING
INTO THE 20S REGIONWIDE ALONG WITH A FEW UPPER TEENS ACROSS
NORTHWEST MA. NORMAL OVERNIGHT LOWS SHOULD BE 30- 35 FOR EARLY
APRIL.
MONDAY ... AS MENTIONED ABOVE MODEL GUIDANCE HAS SPED UP ARRIVAL AND
DEPARTURE OF SNOW FROM FRONTAL WAVE. 00Z GFS IS ON THE NORTHERN EDGE
OF THE GUID WITH SFC LOW TRACKING ALONG THE SOUTH COAST...RESULTING
IN PTYPE ISSUES /RAIN & SNOW/ ACROSS CT/RI AND SOUTHEAST MA.
MEANWHILE REMAINDER OF GUID INCLUDING 00Z NAM/ECMWF/GEFS AND 12Z EPS
ARE FARTHER SOUTH AND COLDER. GIVEN TIME RANGE HERE AND SMALL
FRONTAL SCALE SYSTEM A MODEL BLEND IS LIKELY MOST SKILLFUL. THUS
WILL USE A BLEND APPROACH HERE. REGARDING QPF...00Z ECMWF/GFS/GEFS
AND 12Z EPS SUPPORT POTENTIAL QPF OF 0.20 TO 0.50 INCHES ACROSS THE
REGION. PRELIMINARY SNOW FORECAST VERY DIFFICULT AT THIS TIME RANGE
ESPECIALLY WITH SMALL FRONTAL WAVE IN ADDITION TO POTENTIAL PTYPE
ISSUES. FURTHERMORE ACCUMULATING SNOW ON PAVED SURFACES IN APRIL SNOW
EVENTS /HIGH SUN ANGLE...WARM GROUND AND LONGER DAYS THAN NIGHTS/
HINGE ON INTENSITY OF QPF. IF INTENSITY IS LACKING MOST ACCUMULATION
IS CONFINED TO THE COLDER SURFACES/HIGHER TERRAIN AND SECONDARY
ROADS. JUST TOO EARLY FOR ANY INSIGHT WHERE HEAVIER SNOW BANDS
WOULD POTENTIALLY SETUP. STAY TUNED.
MON NIGHT AND TUESDAY ... VERY PROGRESSIVE SYSTEM SO A DRYING TREND
THIS PERIOD. THE EXCEPTION WILL BE OVER COASTAL PLYMOUTH
COUNTY...CAPE COD AND NANTUCKET WHERE NORTHEAST WINDS AND STEEP LOW
LEVEL LAPSE RATES LIKELY RESULT IN OCEAN EFFECT SNOW BANDS. THIS IS
COURTSEY OF VERY COLD AIR ADVECTING IN ON BACKSIDE OF DEPARTING
SURFACE WAVE. IN FACT THIS AIRMASS WILL BE JUST AS COLD IF NOT
COLDER THAN SUNDAY/SUNDAY NIGHT/S AIRMASS WITH H85 TEMPS DOWN TO -
15C 12Z TUE! OTHERWISE EXPECT A VERY CHILLY DAY TUE WITH MUCH OF THE
AREA DRY WITH THE EXCEPTION OF SOUTHEAST MA AS MENTIONED ABOVE. VERY
BLUSTERY IN THE MORNING ACROSS SOUTHEAST MA WITH DEPARTING WAVE AND
1033 MB HIGH ENTERING THE GREAT LAKES.
WED ... LOOKS TO BE A TRANSITION DAY WITH COLD ANOMALOUS TROF
MOVING OFFSHORE AND HIGH PRES BUILDING INTO THE REGION. OFF TO A
COLD START BUT AIRMASS MODIFYING DURING THE DAY. DRY WEATHER
SHOULD PREVAIL BUT RISK OF PRECIP WED NIGHT PENDING SPEED OF NEXT
UPSTREAM SYSTEM.
THURSDAY AND FRIDAY ... COLD ANOMALOUS TROUGH MOVES OFFSHORE SO
TEMPS WILL REBOUND TO MORE SEASONAL LEVELS /50S/. HOWEVER MEAN
TROUGH RELOADS OVER THE GREAT LAKES AND OH VLY. THIS RESULTS IN A
STRONG FRONTAL BOUNDARY APPROACHING THE REGION WITH STRONG WAA
PATTERN INTO SRN NEW ENG. MODELS THEN DIFFER ON LATITUDE OF FRONTAL
WAVE DEVELOPING ON THE FRONT. NONETHELESS UNSETTLED WEATHER LATE
NEXT WEEK. ALSO WILL HAVE TO WATCH INTENSITY AND DURATION OF ANY
COASTAL LOW/FRONTAL WAVE AS ASTRONOMICAL TIDES ARE VERY HIGH...12.0+
FT AT BOSTON. HENCE RISK OF COASTAL FLOODING.
