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December 2009

12/23/2009

Holiday Headaches

THERE ISN'T MUCH CHANGE IN THINKING FROM YESTERDAY. IT STILL LOOKS LIKE WE ARE IN GOOD SHAPE WEATHER WISE THROUGH CHRISTMAS EVE, AND MOST OR ALL, OF TOMORROW NIGHT. THAT IS GOOD NEWS FOR LAST MINUTE SHOPPERS AND PEOPLE WHO WILL BE TRAVELING NEARBY. IT ALSO STILL APPEARS THAT WE ARE IN LINE FOR MAINLY A RAIN EVENT OUT OF THIS NEXT SYSTEM AS TEMPS GO ABOVE FREEZING ALL ACROSS THE AREA. IN FACT, TEMPS WILL EVENTUALLY PEAK ABOVE 40 IN MANY LOCATIONS, AND READINGS WILL PROBABLY SURGE INTO THE 50S AS CLOSE BY AS THE DELMARVA PENINSULA AND MAYBE UP INTO SOUTHERN NJ.

THERE ARE THREE MAIN PROBLEMS THAT WE WILL ENCOUNTER DURING THE NEXT FEW DAYS... (1) FRONT-END ICE - OUR FEELING IS THAT TEMPS FROM THE CITY SOUTH AND EAST WILL BE ABOVE FREEZING BY THE TIME ANY PRECIP GETS IN. HOWEVER, FROM THE CITY NORTH AND WEST, THERE IS MORE CONCERN ABOUT THE RAIN FREEZING ON UNTREATED SURFACES FOR AWHILE, AND ALSO THE CHANCE OF A LITTLE SLEET. THE LONGER IT TAKES FOR THE PRECIP TO GET HERE, THE FEWER PROBLEMS WE WILL HAVE, AS TEMPS WILL HAVE A CHANCE TO RISE A BIT MORE. AT THIS STAGE, WE THINK THAT ANY SIGNIFICANT RAIN DOES NOT GET INTO THE NYC AREA UNTIL 4-7 PM FRIDAY. THERE IS A SMALL CHANCE THAT SOME DRIZZLE OR FREEZING DRIZZLE BREAKS OUT AT LEAST SEVERAL HOURS EARLIER THAN THAT AS THE LOW LEVELS QUICKLY MOISTEN UP DUE TO THE EASTERLY WIND FLOW. THE GFS AND MM5 SHOW THAT HAPPENING TO THE SOUTH AND WEST OF THE CITY, WHILE THE NAM, CANADIAN, AND UKMET DO NOT.  WE MAY NOT KNOW FOR SURE IF IT IS GOING TO HAPPEN UNTIL THE LAST MINUTE.

(2) FLOODING, DUE TO SNOW MELT AND RAIN - WE HAVEN'T CHANGED OUR THINKING ON THIS VERY MUCH DURING THE PAST COUPLE OF DAYS. WE STILL FEEL THAT THE FARTHER NORTH AND WEST YOU GO, THE LESS MELTING THERE WILL BE SINCE TEMPS NEVER REALLY GET ALL THAT MILD IN THE FIRST PLACE. THE GREATEST MELTING WILL OCCUR SOUTH AND EAST OF THE I-95 CORRIDOR, WHERE TEMPS WILL PEAK AT THE HIGHEST LEVELS. RAINFALL TOTALS NOW LOOK A TAD BEEFIER THAN THEY DID YESTERDAY, WITH A GOOD CHANCE OF AN INCH OR SO...PERHAPS AS MUCH AS 1.5". THAT IS PROBABLY NOT ENOUGH RAIN TO CAUSE MAJOR FLOODING PROBLEMS. HOWEVER, SOME MINOR FLOODING...PONDING OF WATER ON STREETS, POOR DRAINAGE AREA FLOODING, ETC. IS LIKELY. THAT WILL BE ACCENTUATED WHERE STORM DRAINS ARE CLOGGED UP BY SNOW.

(3) FOG - WITH HIGHER DEW POINTS ON THE WAY, OVERRIDING THE COLD, SNOW COVERED GROUND, AT LEAST SOME FOG IS LIKELY TO FORM. THE RAIN FALLING WILL ADD MORE MOISTURE TO THE MIX. OUR FEELING IS THAT FOG WILL BE MOST DENSE WHERE WINDS ARE ABLE TO STAY LIGHT ENOUGH, BUT THERE IS THE CHANCE THAT WE HAVE A PERIOD OF FAIRLY WIDESPREAD FOG ACROSS THE REGION FRIDAY NIGHT INTO SATURDAY MORNING. AGAIN, THIS IS SOMETHING THAT WE WILL EXAMINE AGAIN DURING THE NEXT COUPLE OF DAYS. FOLLOWING THIS SYSTEM, DRY WEATHER WILL RETURN ON SUNDAY, THEN WE'LL HAVE A TURN TO COLDER WEATHER EARLY NEXT WEEK.

12/21/2009

WHITE CHRISTMAS...ICY AND WET TOO

HAPPY WINTER! AT 12:47 P.M. TODAY, IT BECAME OFFICIAL, WITH THE OCCURRENCE OF THE WINTER SOLSTICE. OF COURSE, IF YOU TOLD SOMEONE THIS WEEKEND, ESPECIALLY DURING THE HEIGHT OF THE SNOWSTORM ON SATURDAY NIGHT, THAT IT WASN'T WINTER YET, THEY PROBABLY WOULD HAVE LAUGHED AT YOU! THAT WAS QUITE THE STORM. AS WE EXPECTED, THERE WAS A PRETTY SHARP GRADIENT IN SNOWFALL TOTALS WITH IT FROM NORTH TO SOUTH. FOR THE CORE OF THE HEAVIEST SNOW ZONE, THIS STORM WAS DEFINITELY AN OVER-ACHIEVER.

WITH THE DEEP SNOW COVER IN PLACE NOW, THIS PRETTY MUCH INSURES US OF A WHITECHRISTMAS...ALL BE IT A STALE ONE. AS WE GO FORWARD DURING THIS WEEK AND HEAD TOWARD CHRISTMAS DAY, IT APPEARS THAT WE WILL BE DEALING WITH FAIRLY QUIET WEATHER THROUGH THURSDAY. IT WILL REMAIN DRY, AND SKIES WILL BE NO WORSE THAN PARTLY CLOUDY. TEMPS THROUGH THURSDAY WILL FLUCTUATE SOMEWHAT, BUT WILL REMAIN ON THE COLD SIDE OF NORMAL. IT ACTUALLY LOOKS A FAIRLY IMPRESSIVE, LOW LEVEL PUSH OF COLD AIR IS ON THE WAY FOR WEDNESDAY AND THURSDAY AS HIGHPRESSURE BUILDS OVER EASTERN CANADA. THAT WILL SET THE STAGE FOR POTENTIAL PROBLEMS HERE ON CHRISTMAS DAY.

A FAIR AMOUNT OF WARMING WILL TAKE PLACE ALOFT LATE THIS WEEK, WHICH WILL DIMINISH AND POSSIBLY TOTALLY NEGATE ANY CHANCES OF GETTING NEW SNOW. HOWEVER, WITH THE LOW LEVELS BE PRETTY CHILLY INITIALLY, WE ALMOST CERTAINLY WILL HAVE SOME FRONT-END ICE PROBLEMS, ESPECIALLY FROM THE CITY ON NORTH AND WEST. THIS LOOKS LIKE A CLASSIC SETUP ON FRIDAY AND FRIDAY NIGHT WHERE MILDER AIR WILL BE ABLE TO EASILY SURGE UP THE COASTAL PLAIN, AND ALSO UP WEST OFTHE MOUNTAINS, THROUGH THE OHIO VALLEY AND INTO THE EASTERN GREAT LAKES REGION. HOWEVER, FROM THE APPALACHIANS EASTWARD TO THE FALL LINE, THE LOW LEVEL COLD AIR WILL BE VERY STUBBORN, PARTICULARLY IN THE DEEPER MOUNTAIN VALLEYS, AND ALSO IN PLACES SUCH AS HARRISBURG AND ALLENTOWN, PA, POUGHKEEPSIE, NY, AND DANBURY, CT.

WE WILL OBVIOUSLY FINE TUNE THIS FORECAST DURING THE NEXT FEW DAYS. HOWEVER, AT THIS POINT, BE PREPARED FOR AT LEAST SOME SLEET AND FREEZING RAIN BEFORE ANY CHANGEOVER TO PLAIN RAIN. WITH ALL OF THE SNOW ON THE GROUND, TEMPS GOING ABOVE FREEZING, AND A DECENT AMOUNT OF RAIN ON THE WAY, THE CONCERN DEFINITELY SHIFTS TO THE POTENTIAL FOR FLOODING. OUR THINKING RIGHT NOW IS THAT THE FARTHER INLAND YOU GO, THE CHILLIER THE TEMPS WILL BE, AND THE LESS MELTING THAT WILL OCCUR. WHEN THE PRECIP DOES EVENTUALLY CHANGE OVER TO RAIN IN THOSE AREAS, MUCH OF IT MAY JUST GET ABSORBED INTO THE SNOW PACK, AS OPPOSED TO EXTENSIVE MELTING. HOWEVER, THE CLOSER TO THE COAST YOU GO, THE HIGHER THE TEMPS WILL EVENTUALLY SPIKE, THUS LEADING TO GREATER SNOW MELT AND THE HIGHER POTENTIAL FOR FLOODING...WHEN YOU COMBINE THAT WITH THE RAIN FALLING. EITHER WAY YOU SLICE IT, CHRISTMAS DAY INTO FRIDAY NIGHT LOOKS AT LEAST SOMEWHAT STORMY.

12/18/2009

BLIZZARD WARNING FOR LONG ISLAND!

THE BIGGEST SNOWSTORM SINCE EARLY MARCH IS BEARING DOWN ON US. THIS IS A VERY RIPE SITUATION, WITH PLENTY OF MOISTURE COMING UP FROM THE SOUTH, A STRONG UPPER LEVEL SHORT WAVE NOW GETTING READY TO ROUND THE BASE OF THE TROF, AND A DEVELOPING SURFACE LOW PRESSURE SYSTEM OVER THE SOUTHEAST.

THERE ARE STILL SOME UNCERTAINTIES, EVEN THIS LATE IN THE GAME. THERE IS NO DOUBT THAT SNOW IS ON THE WAY, AND WE ARE CONFIDENT THAT THIS WILL BE A BIG SNOWFALL. WE NOW HAVE THE CITY CLEARLY IN THE 6-12" ZONE. HOWEVER, WE DON'T FEEL THAT YOU WILL HAVE TO GO TOO FAR NORTH AND NORTHWEST OF THE CITY TO GET LESS THAN 6". IN FACT, THERE IS LIKELY TO BE A REALLY SHARP DOWNWARD GRADIENT TO THE NORTH. WE ARE MENTIONING A FOOT OR MORE IN SOME LOCATIONS, WITH PERHAPS A LOCAL AMOUNT AS HIGH AS 15-18 INCHES. HOWEVER,

THE HIGHER ELEVATIONS OF SOUTHWESTERN VA SEEM TO BE IN LINE FOR UPWARDS TO 18" OF SNOW. WE EXPECT THAT BULLSEYE AREA TO GRADUALLY PENCIL OUT AS IT COMES OUT OF THE MOUNTAINS AND RUNS EASTNORTHEASTWARD. THERE MAY EVENTUALLY BE A SECONDARY BULLSEYE ZONE IN EXTREME SOUTHEASTERN NEW ENGLAND AND THE EASTERN TIP OF LONG ISLAND, AS THE STORM REALLY BOMBS OUT TOMORROW NIGHT AND EARLY SUNDAY. WINDS WILL BE INCREASING BIG TIMEHERE TOMORROW, AND IT WILL REMAIN VERY WINDY TOMORROW NIGHT AND EARLY SUNDAY.

 SO, WITH THE HEAVY SNOW AND TEMPS MOSTLY IN THE 20S DURING THE STORM, BLOWING AND DRIFTING SNOW WILL BE A PROBLEM IN OPEN AREAS. IN FACT, IT WILL PROBABLY EVEN SEEM LIKE A BLIZZARD AT TIMES! WE EXPECT PEAK WIND GUSTS TO BE NEAR 40 MPH IN THE CITY, WITH 50+ MPH GUSTS OUT NEAR MONTAUK AND INTO SOUTHEAST NEW ENGLAND. WITH THE CYCLONIC CURVATURE SUNDAY MORNING, SNOW AND FLURRIES WILL LINGER FOR AWHILE. FOLLOWING THE STORM, THE REST OF SUNDAY LOOKS DRY WITH CLOUDS TRYING TO BREAK FOR SOME SUN. HOWEVER, IT WILL REMAIN BLUSTERY AND COLD.

ONE LAST NOTE. ALTHOUGH THE WINDS WILL BE GETTING QUITE STRONG, THEY WILL ONLY BE BLOWING OUT OF THE NORTHEAST FOR A RELATIVELY SHORT PERIOD OF TIME BEFORE SWINGING AROUND INTO THE NORTH. SO, THE COASTAL FLOODING AND BEACH EROSION PROBLEMS WILL BE MINOR TO AT WORST MODERATE.

12/17/2009

Nor'easter or Not?

EVERYTHING IS NOW POINTING TO A MAJOR SNOWSTORM FOR THE MID-ATLANTIC REGION, WITH A CLOSE CALL FOR AREAS FARTHER NORTH AND NORTHEAST. AS WE FELT YESTERDAY AT THIS TIME, IT LOOKS QUITE LIKELY THAT AT LEAST SOME SNOW WILL FALL HERE. HOWEVER, THERE WILL PROBABLY BE A VERY SHARP EDGE TO THE SNOW ON THE NORTH OR NORTHWEST SIDE OF THIS SYSTEM. TRYING TO FIGURE OUT EXACTLY WHERE THAT SETS UP WILL BE A TOUGH CALL.

AT THE SAME TIME, WE EXPECT A VERY SHARP GRADATION IN SNOWFALL AMOUNTS TO THE SOUTH.  THIS LOOKS LIKE A CLASSIC SITUATION WHERE THE PRECIP WILLEVENTUALLY RUN INTO A "BRICK WALL" NORTH OR NORTHWEST OF A CERTAIN POINT. HOWEVER, WITH THE CONFLUENCE ZONE SHIFTING NORTHWARD FAIRLY FAR, AT LEAST FOR A TIME, WE DO EXPECT SOME LIGHT SNOW TO MAKE DECENT PROGRESS NORTHWARD. WE STILL WANT TO LOOK AT THE TRENDS OF THE MODELS DURING THE NEXT 24 HOURS. MORE IMPORTANTLY, WE WANT TO SEE HOW THE ACTUAL WEATHER, INCLUDING THE UPPER-AIR FLOW PATTERN, TURNS OUT IN THE SHORT TERM. WE STILL HAVE ROOM TO FINE TUNE OUR SNOWFALL FORECAST, BUT OUR PRELIMINARY IDEA IS THAT THE CORE OF OUR AREA PICKS UP 1-3", WITH 3-6" ACROSS THE SOUTHERN HALF OF NJ AND THE EASTERN HALF OF LONG ISLAND. FOR PLACES SUCH AS BALTIMORE AND WASHINGTON, DC, THIS COULD VERY WELL BE THE BIGGEST SNOWSTORM SINCE THE PRE-VALENTINE'S DAY STORM OF 2006.

IT DOES APPEAR THAT THERE WILL BE ENOUGH BACKING OF THE UPPER FLOW TO ALLOW THE SURFACE LOW TO TRACK RELATIVELY CLOSE TO THE COAST AS IT IS DEEPENING. WE STILL FEEL THAT THE BEST UPWARD MOTION WILL LIKELY PASS BY TO THE SOUTH AND EAST OF THE CITY. OBVIOUSLY, IF THE STORM TRACKS A TAD FARTHER SOUTH AND EAST, THEN SNOW AMOUNTS WILL END UP BEING LESS AND THE CITY MAY BE HARD PRESSED TO GET MORE THAN A COATING. HOWEVER, IF THE SHORT WAVE REALLY SHARPENS UP AND TAKES ON A NEGATIVE TILT QUICKLY...AND PERHAPS EVEN CLOSES OFF...THEN THIS ENTIRE STORM AND ITS HEAVY SNOW SHIELD WILL END UP BEING FARTHER NORTH THAN WE NOW EXPECT. THERE IS A CHANCE THIS STORM REALLY CRANKS UP MORE THAN WE ARE BARGAINING FOR, AND ALL OF A SUDDEN NYC IS IN THE 6-12" ZONE!!! THIS IS A FLUID SITUATION, AND MORE UPDATES ARE ON THE WAY.

FOLLOWING THE STORM, SUNDAY LOOKS WINDY AND COLD. THERE MAY BE SOME LEFTOVER SNOW OR FLURRIES AROUND SUNDAY MORNING, THEN THE AFTERNOON HOURS WILL BE DRY. IN THE MEANTIME, OUR WEATHER WILL BE QUIET THROUGH TOMORROW, BUT COLD. THE GOOD NEWS IS THAT WE ARE SOON GOING TO LOSE THE GUSTY WIND THAT HAS BEEN WITH US FOR AWHILE.

12/14/2009

One more mild day

THE GOOD NEWS ON THIS 14TH DAY OF DECEMBER IS THAT OUR WEATHER FOR MOST OF THE WEEK WILL BE QUIET. THERE ARE A LOT OF DIFFERENT POSSIBLE SCENARIOS FOR THE WEATHER HERE THIS WEEKEND. HOWEVER, UNTIL THEN, NO MAJOR STORMS WILL AFFECT OUR WEATHER. IT REMAINS TO BE SEEN WHETHER THERE WILL BE ONE MAJOR SYSTEM THAT COMES OUT IN THE FRIDAY-SATURDAY TIME FRAME, LIKE THE CANADIAN MODEL IS SUGGESTING, OR IF THERE ARE TWO SEPARATE PIECES...ONE ON FRIDAY, AND ANOTHER ON SUNDAY...ALONG THE LINES OF THE GFS AND EUROPEAN MODELS.

MY EARLY TAKE ON THIS IS THAT IF THERE ARE TWO SYSTEMS, THEN IT IS THE SECOND ONE THAT HAS A BETTER CHANCE TO CUT FARTHER NORTHWARD AND END UP BEING AMAJOR STORM. THAT'S BECAUSE OF THE TILTING OF THE ORIENTATION OF THE UPPER LEVEL TROF,IN RESPONSE TO ANOTHER SHORT WAVE PUSHING SOUTHWARD ON THE WESTERN END OF THE TROF. WE WILL JUST HAVE TO REVISIT THIS ISSUE AGAIN AND AGAIN OVER THE NEXT FEW DAYS UNTIL WE FINALLY HAVE A GOOD CONSENSUS.

A COLD FRONT WILL CROSS THE REGION TOMORROW, ACCOMPANIED BY SOME CLOUDS AND A WIND SHIFT, BUT NO MORE THAN A BRIEF SHOWER OR SPRINKLE. THERE MAY BE A SNOW SHOWER OR FLURRY TOMORROW NIGHT AS THE UPPER LEVEL TROF AXIS AND A HEALTHY VORT MAX SWING THROUGH. HOWEVER, THAT WILL BE FIGHTING AGAINST A DOWNSLOPING WIND AND DECENT COLD ADVECTION. THE TWO FACTORS MAY JUST CANCEL EACH OTHER OUT. EVEN SO, WE DID DECIDE TO COVER A SNOW SHOWER OR A FLURRY IN THE FORECAST AS A MENTION.

BEHIND THE TROF, THE REST OF THE WORK WEEK LOOKS MAINLY DRY, WITH THE NEXT CHANCE OF ANY PRECIP BEING SOMETIME OVER THE WEEKEND. AS I ALLUDED TO BEFORE, THERE ARE A LOT OF POSSIBILITIES WITH THAT UPCOMING SCENARIO. FORTUNATELY, IT IS ONLY MONDAY, AND WE HAVE PLENTY OF TIME TO FINE TUNE OUR FORECAST AS WE GO FORWARD.

IN THE TEMPERATURE DEPARTMENT, IT WILL BE RELATIVELY MILD THROUGH TOMORROW, THEN COLDER AIR IS ON THE WAY FOR TOMORROW NIGHT AND WEDNESDAY. TEMPS WILL BE SIMILAR HERE ON THURSDAY, FRIDAY, AND SATURDAY. SINCE A REINFORCING COLD FRONT IS LIKELY TO PASS THROUGH THE AREA LATE THURSDAY OR THURSDAY EVENING, TEMPS HERE ON FRIDAY COULD BE A COUPLE OF DEGREES LOWER THAN THURSDAY, IF NOT MORE. SPEAKING OF THAT LATE THURSDAY FRONT, WE WILL HAVE TO KEEP A CLOSE EYE ON IT DURING THE NEXT COUPLE OF DAYS, AS THERE SEEMS TO BE A DECENT AMOUNT OF SURFACE CONVERGENCE WITH IT. GRANTED, THE AIR WILL BE DRY, BUT IT WOULD NOT BE SURPRISING IF WE END UP WITH A SKINNY LINE OF SOUTHWARD PUSHING SNOW SHOWERS ALONG THAT FRONTAL BOUNDARY.

IN THE MEANTIME, A PARTLY TO MOSTLY CLOUDY NIGHT IS COMING UP WITH NO MORE THAN A STRAY SPRINKLE.

12/08/2009

Messy morning

FROM THE CITY SOUTHWARD THROUGH EASTERN NJ AND EASTWARD OUT ON MOST OF THE ISLAND, THIS WILL JUST BE A RAIN EVENT. TO THE NORTH AND WEST OF NYC, THE AIR WILL BE COLD ENOUGH FOR AWHILE FOR A BRIEF PERIOD OF SNOW AND SLEET ON THE FRONT END...BEFORE THE PRECIP QUICKLY CHANGES OVER TO RAIN. THE FARTHER NORTH AND WEST YOU GO, THE LONGER THE DURATION OF SNOW AND ICE, AND THE MORE ROAD PROBLEMS THERE WILL BE. HOWEVER, YOU WILL HAVE TO GET OUT FAIRLY FAR NORTH AND WEST TO GET INTO THE 1-3" ACCUMULATION ZONE...PROBABLY NORTH AND WEST OF A LINE FROM SOUTHERN WARREN COUNTY, NJ TO NORTHERN FAIRFIELD COUNTY, CT.

WITH THE PRIMARY LOW CUTTING WELL TO OUR NORTH AND WEST, WE DO EXPECT A GOOD SURGE OF MUCH MILDER AIR TO MOVE UP WEST OF THE APPALACHIAN MOUNTAINS, AND ALSO UP THE COASTAL PLAIN. FROM THE FALL LINE BACK INTO THE PIEDMONT REGION AND UP TO THE CREST OF THE MOUNTAINS, THE CHILLY AIR WILL BE HARDER TO DISLODGE, AND HIGH TEMPS IN THESE AREAS WILL NOT BE REACHED UNTIL AFTER THE OCCLUSION GOES BY. WE DO EXPECT A TRIPLE POINT LOW TO FORM SOMEWHERE BETWEEN THE EASTERN SHORE OF THE CHESAPEAKE BAY AND SOUTHERN NJ. JUST WHERE THAT TRIPLE POINT LOW DEVELOPS WILL DETERMINE THE NORTHERNMOST EXTENT OF THE REALLY BALMY AIR. ASIDE FROM THE MINOR FROZEN PRECIP PROBLEMS, THE BIGGER, MORE WIDESPREAD CONCERN FROM THIS STORM WILL BE A SHORT BUT VERY INTENSE BURST OF HEAVY RAIN.

RAINFALL TOTALS WILL BE ON THE ORDER OF 1.25" AND 1.75", WITH THE POTENTIAL FOR OVER 2" IN PARTS OF THE AREA. A LOT OF THAT RAIN WILL OCCUR DURING A 5 OR 6 HOUR TIME PERIOD. THAT COULDOBVIOUSLY LEAD TO SOME LOCALIZED FLOODING PROBLEMS. TOMORROW MORNING'S RUSH HOUR LOOKS REALLY WET! TEMPS WILL BOTTOM OUT TONIGHT WITH THE WET BULBING EFFECT, THEN SLOWLY RISE LATE TONIGHT.

TEMPS WILL SPIKE TO MILDER LEVELS TOMORROW, BUT THEN THE FLOODGATES OF COLD WILL BE OPENED UP BY THURSDAY, AND IT WILL STAY QUITE COLD FRIDAY INTO THE UPCOMING WEEKEND. READINGS WILL BE MAINLY IN THE 30S ON THURSDAY, AND FRIDAY NOW LOOKS TO BE OUR COLDEST DAY OF THE NEXT 4 OR 5 DAYS. TO ADD TO THE WINTERLIKE FEEL LATE THIS WEEK, STRONG WINDS WILL GUST TO OR PAST 40 MPH AT TIMES, MAKING IT FEEL MUCH COLDER THAN IT REALLY IS.

OVER THE WEEKEND, WE MAY HAVE TO CONTEND WITH ANOTHER SYSTEM. HOWEVER, EARLY INDICATIONS ARE THAT THERE WILL BE A NORTHERN BRANCH AND A SOUTHERN BRANCH FEATURE COMING ALONG IN THE FLOW. IF THEY PHASE SOMEWHAT, THEN WE COULD END UP WITH A DECENT SNOW EVENT HERE. HOWEVER, IF THEY STAY SEPARATE ENTITIES AND NEVER PHASE, THEN WE ACTUALLY COULD END UP BEING IN THE RIPOFF ZONE BETWEEN THE TWO SYSTEMS. I WILL HAVE MORE ON THAT SITUATION IN LATER BLOGS.

12/04/2009

Wet to White Saturday

IF YOU LOOK AT A TEMPERATURE CURVE FOR OUR AREA, YOU'LL FIND THAT, ON AVERAGE, THE COLDEST THREE MONTHS OF THE YEAR RUN FROM ABOUT DECEMBER 5TH TO MARCH 5TH. THIS PERIOD IS OFTEN REFERRED TO AS METEOROLOGICAL WINTER. THE UPCOMING WEATHER PATTERN WILL BE RIGHT IN LINE WITH THE CALENDAR! IN FACT, IT IS INTERESTING TO NOTE THAT IN THE PAST 10 YEARS, THERE HAS BEEN AT LEAST A TRACE OF SNOW DURING THE FIRST WEEK TO 10 DAYS OF DECEMBER IN 6 OF THE YEARS. WE WILL BE ADDING ANOTHER YEAR TO THAT TREND TOMORROW.

FINALLY, AFTER A FEW DAY BATTLE BETWEEN THE NAM AND GFS, THE MODELS NOW ARE IN AMAZINGLY GOOD AGREEMENT. ALTHOUGH THE EVENT HAS YET TO HAPPEN, IT APPEARS THAT THE NAM WILL GET THE VICTORY IN THIS FIGHT.  AS WE HAVE BEEN SAYING FOR THE PAST COUPLE OF DAYS, THIS IS A SITUATION WHERE WE WILL WASTE AT LEAST SOME OF THE LIQUID IN THIS STORM DUE TO A RELATIVELY WARM BOUNDARY LAYER...AND, OF COURSE, THE WARM GROUND. EVEN WITH THE RELATIVELY MILD TEMPS IN THE LOWEST THOUSAND FEET OR SO OF THE ATMOSPHERE, IT WILL BE COLD ENOUGH ALOFT ALL DAY TOMORROW FOR SNOW. SO, IT IS A MATTER OF HOW HARD THE PRECIP WILL BE FALLING. THAT WILL HAVE A DIRECT CORRELATION WITH THE INTENSITY OF THE UPWARD MOTION. WE BEGAN TO SEE THE TREND YESTERDAY OF THE UPWARD MOTION MAX SHIFTING A LITTLE FARTHER NORTH WITH EACH RUN OF THE MODELS.

NOW, THE NAM AND GFS ARE MATCHING UP FAIRLY CLOSELY WITH THAT ZONE, EVENTUALLY LINING UP WITH OR SLIGHTLY SOUTHEAST OF THE I-95 CORRIDOR FOR A PERIOD. IT NOW APPEARS THAT THE BEST UPWARD MOTION WILL BE FOCUSED DURING AN INTERVAL A TAD EARLIER THAN WE HAD THOUGHT YESTERDAY, RUNNING FROM MAYBE 4 PM TO 10 PM, RATHER THAN 6 PM TO MIDNIGHT. THAT MEANS THAT WE HAVE TO BE ON GUARD FOR RAPID AND VERY NOTICEABLE CHANGES TAKING PLACE IN THE REGIONAL WEATHER DURING THE MID TO LATE AFTERNOON HOURS TOMORROW...OR AT THE LATEST, THE EARLY EVENING. FOR THE PAST COUPLE OF DAYS WE HAVE BEEN STRESSING THAT A VERY KEY INGREDIENT IN THIS SETUP WOULD BE THE TILT OF THE UPPER LEVEL SHORT WAVE. NOW, THE MODELS ARE IN GOOD AGREEMENT THAT THE SYSTEM WILL TRY TO GO AROUND TO A SLIGHT NEGATIVE TILT AT THE LAST MOMENT BEFORE IT HEADS OUT TO SEA. THAT WILL PROBABLY ALLOW FOR SOMEWHAT MORE DEEPENING OF THE SURFACE LOW, AND MORE WELL DEFINED CYCLONIC CURVATURE AND THUS SURFACE CONVERGENCE. SO, WHAT THIS ALL BOILS DOWN TO IS A BEEFIER LOOKING STORM OVERALL, AS WELL AS GREATER QPF. WE FEEL THAT NOT TOO FAR NORTH AND WEST OF THE CITY, THE ATMOSPHERE WILL COLD ENOUGH THROUGH THE COLUMN FOR ALL SNOW TO FALL. THAT IS WHERE WE HAVE THE MAX SNOWFALL TOTALS, WITH A SMALL 3-6" IN THE HIGHER ELEVATIONS FROM THE SOUTHEAST POCONOS THROUGH NORTHWEST NJ AND SOUTHEAST NY STATE. FARTHER NORTH AND WEST FROM THERE, THE PRECIP AMOUNTS WILL BE LIGHTER AND THE UPWARD MOTION NOT AS GREAT. WE JUMP OVER THE LOW ELEVATIONS OF THE HUDSONVALLEY, AND HAVE ANOTHER BULLSEYE AREA IN NORTHWEST CT AND SOUTHWEST MA. ON THE OTHER EXTREME SIDE OF THINGS, WE FEEL THAT THIS WILL BE MAINLY A RAIN EVENT FROM THE DELMARVA PENINSULATHROUGH COASTAL NJ AND  EXTREME EASTERN LI. HOWEVER, EVEN IN THESE AREAS, WE ARE COVERING FOR A COATING OF SNOW AT THE END OF THE STORM AS COLDER AIR MOVES IN. WHILE WE DO FEEL FAIRLY CONFIDENT ABOUT OUR FORECAST, THERE IS SOME DEGREE OF NERVOUSNESS, GIVEN THE LAST MINUTE TILTING OF THE SHORT WAVE TO NEGATIVE AND THE POTENTIAL FOR EXPLOSIVE DEVELOPMENT CLOSER TO THE COAST THAN WE ARE BARGAINING FOR.

WHAT COULD GO WRONG? WELL, THE CHANGEOVER MAY HAPPEN EARLIER IN AND NEAR THE CITY, LEADING TO A FEW INCHES RATHER THAN OUR COATING TO AN INCH. THE 3-6" ZONE THAT WE HAVE ON THE MAP COULD BE LARGER, AND MAY BE TUCKED IN FAIRLY CLOSE TO THE I-95 STRIP. FINALLY, IT IS POSSIBLE THAT THERE IS A SECONDARY BULLSEYE OF SNOWFALL TOTALS THAT ACTUALLY ENDS UP BEING SOUTH AND EAST OF I-95...FAIRLY CLOSE TO THE COAST. WITH DECENT COLD ADVECTION BEHIND THE DEPARTING STORM TOMORROW NIGHT, TEMPS WILL DROP TO FREEZING IN THE CITY FOR THE FIRST TIME THIS SEASON. IN ALL AREAS, WE HAVE TO WATCH OUT FOR ROADS BECOMING ICY LATER TOMORROW NIGHT. SUNDAY LOOKS BRISK AND CHILLY WITH PLENTY OF SUNSHINE AS THE STORM RACES AWAY QUICKLY OUT TO SEA, AND HIGH PRESSURE BUILDS IN FROM THE WEST. WE DID MAKE SOME DOWNWARD TEMP TWEAKS IN THE FORECAST FOR EARLY NEXT WEEK. THEN, MORE FUN AND GAMES ARE ON THE WAY BY WEDNESDAY.

12/02/2009

Stormy night ahead...

BEFORE WE TALK ABOUT THE UPCOMING PATTERN HERE FROM TONIGHT THROUGH THEWEEKEND, HERE ARE SOME INTERESTING TEMPERATURE STATS FOR THE PARK...SO FAR THIS FALL, WE HAVE YET TO REACH 32 DEGREES. THE AVERAGE DATE OF THE FIRST 32 OF THE SEASON IS NOVEMBER 10TH OR 11TH. HERE ARE THE DATES OF THE FIRST 32 OR LOWER DURING THE PAST 5 YEARS: NOV 18, 2008; NOV 11, 2007; DEC 4, 2006; NOV 18, 2005; NOV 9, 2004.

NOW, ONTO THE CURRENT SETUP. ON THE LATEST WEATHER MAP, WE SEE A LOW PRESSURE SYSTEM OVER THE SOUTHEASTERN STATES, WITH A HIGH RETREATING FARTHER OFF THE EAST COAST. DURING TONIGHT, WE'LL BE IN GOOD SOUTHEAST FLOW OF INCREASINGLY MOIST AND MILD AIR. WITH THE LOW TRACKING TO OUR WEST TONIGHT, IT WILL DRAG THE WARM FRONT NORTHWARD. THAT WILL AT FIRST CAUSE A PERIOD OF OVERRUNNING RAIN HERE, WITH SOME OF THE RAIN BEING HEAVY. AS DEW POINTS AND TEMPS RISE OVERNIGHT, WE ALSO HAVE THE POTENTIAL FOR A T-STORM AT SOME POINT, OR AT LEAST A RUMBLE OF THUNDER.  WITH A STRONG LOW LEVEL JET MOVING OVERHEAD LATE TONIGHT, THERE IS THEPOTENTIAL FOR STRONG AND PERHAPS EVEN DAMAGING WINDS, IF ANY OF THAT HIGHER VELOCITY WIND FROM ALOFT CAN BE PULLED DOWN TO THE SURFACE. THE BRUNT OF THE STORM WILL BE BETWEEN 10PM AND 6AM.

 AS FOR RAINFALL TOTALS WITH THIS SYSTEM, IT LOOKS LIKE A GENERAL INCH...GIVE OR TAKE, WITH A FEW SPOTS PICKING UP AS MUCH AS 1.5" TO 2.0". DRIER AIR WILL RETURN TOMORROW AS THE LOW PULLS NORTHEASTWARDTHROUGH UPSTATE NY AND EVENTUALLY NORTHERN NEW ENGLAND. AS A RESULT, RAIN WILL END IN THE MORNING, THEN CLOUDS WILL BREAK FOR SOME SUN HERE FOR THE BALANCE OF TOMORROW, BUT IT WILL REMAIN GUSTY.

TEMPS TONIGHT WILL DROP A BIT EARLY, THEN HOLD STEADY OR SLOWLY RISE FROM HOUR TO HOUR OVERNIGHT OUR HIGH TEMP IN THE 60S WILL BE REACHED EARLY TOMORROW. AFTER THAT POINT, TEMPS WILL LEVEL OFF AND SLOWLY FALL FOR THE REMAINDER OF THE DAY TOMORROW.

DRY, CHILLIER WEATHER WILL BE THE RULE TOMORROW NIGHT AND FRIDAY. THEN, WE WILL HAVE TO KEEP A CLOSE EYE ON THESATURDAY SITUATION. DEPENDING ON THE STRENGTH AND TRACK OF THAT NEXT SHORT WAVE, WE MAY OR MAY NOT BE DEALING WITH SOME SNOW HERE ON SATURDAY.  AT THIS POINT, IT LOOKS LIKE A GLANCING BLOW WITH A PERIOD OF WET SNOW OR RAIN. ONE THING THAT WE ARE FAIRLY CONFIDENT OF IS THAT A CHILLY WEEKEND IS COMING UP.