AREA FORECAST DISCUSSION
NWS NORTHERN INDIANA
AFDFWA 1214 PM EST THU FEB 19 2004
.AVIATION...
VFR TO PREVAIL TODAY AND THIS EVENING...WITH DETERIORATING
CONDITIONS LATER TONIGHT INTO FRIDAY MORNING. WARM FRONT TO PUSH
NORTH THROUGH THE TERMINALS IN THE PRE-DAWN HOURS FRIDAY MORNING AS
LOW PRESSURE APPROACHES THE SOUTH TIP OF LAKE MICHIGAN BY THE END OF
THE FORECAST PERIOD. SCATTERED SHOWERS AND PATCHY FOG WILL BE
POSSIBLE AROUND DAWN...WITH SHOWERS BECOMING MORE WIDESPREAD OVER
THE COURSE OF THE MORNING WITH BORDERLINE MVFR/IFR CONDITIONS.
&&
.PREV DISCUSSION...
SHORT TERM...
PROFILER/ACARS/ASOS INDICATE STILL FAIRLY GOOD MIXING OVER CWA WITH
ONLY LIGHT FOG. WITH SURFACE RIDGE MOVG INTO THE AREA WIND MAY DIE
OFF ENOUGH FOR SOME THICKER FOG OVER NWRN PORTION OF CWA AROUND DAWN
SO HAVE CONTINUED WITH MENTION THERE BUT DROPPED IN SE WHERE WINDS A
LITTLE STRONGER AND DEWPOINTS LOWER.
MODELS IN GOOD AGREEMENT THAT RIDGE WILL MOVE QUICKLY EAST TODAY AND
A WARM FRONT WILL DEVELOP FROM CENTRAL OH/IN/IL SW TO INTENSIFYING
SOUTHERN PLAINS LOW. DECENT LIFT WILL DEVELOP IN THE WAA REGIME
TODAY BUT MOISTURE LACKING FOR ANY PRECIP AND WILL JUST GO WITH
PARTLY CLOUDY SKIES. DRY LAYER IN MID LEVELS SHOULD PERSIST TONIGHT
BUT AS SURFACE LOW LIFTS NE INTO MID MS VALLEY LOW LEVEL MOISTURE
WILL INCREASE. THIS COMBINED WITH FAIRLY STRONG/DEEP LIFT SHOULD
RESULT IN SOME LIGHT RAIN/DRIZZLE DVLPG. WENT WITH HIGHEST POPS NW
WHERE GREATEST MOISTURE FCST BUT KEPT IN CHC CATEGORY AS STILL
QUESTIONABLE IF IT WILL BE MORE THAN A TRACE EVENT OVERNIGHT. WITH
RELATIVELY WARM MOIST AIR OVERSPREADING COLD SNOW COVERED GROUND
LEFT AREAS OF FOG IN FCST OVER MOST OF THE AREA TONIGHT. GENERALLY
WENT WITH MOS CONSENSUS FCST FOR TEMPS AS GUIDANCE FAIRLY CLOSE.
LONG TERM...
FRIDAY THROUGH WEDNESDAY...GFS SHOWING CONSISTENCY IN THE TRACK OF
THE SFC LOW ACROSS NE IL AND SW LOWER MI...BUT THE GFS MODEL TRENDS
OF TOO SLOW AND NOT DEEP ENOUGH WITH THE SFC LOW CONTINUE...THE LAST
SEVERAL RUNS BACK TO MONDAY EVENING HAVE SHOWN A DEEPER AND MORE
PROGRESSIVE SYSTEM. LAST NIGHTS RUN WAS ABOUT 6 HOURS FASTER WITH
THE SFC LOW FOR FRIDAY EVENING THAN THE RUN FROM THE PREVIOUS NIGHT.
MOS FROM NGM...ETA AND GFS ALL ARE SHOWING STRONGER WIND SPEEDS
FRIDAY. THE MESO ETA WAS SHOWING AN IMPRESSIVE LOW LEVEL WIND FIELD
AT 925 MB ALONG WITH THE DEEPENING SYSTEM FRIDAY MORNING. SO HAVE
RAISED WIND SPEEDS INTO THE BREEZY CATEGORY FRIDAY. HAVE EXTENDED
DURATION OF FOG INTO FRIDAY MORNING OVER ANTICIPATED SNOW COVERED
AREAS IN THE NORTH. SNOW DEPTHS THURSDAY MORNING STILL SHOWED
SEVERAL INCHES AT A NUMBER OF LOCATIONS IN FAR SW LOWER MI. LESS
SNOW COVER WAS OVER N INDIANA AND NW OH. WILL FOLLOW THE TREND OF
THE GFS BRINGING EVEN COLDER AIR THAN EARLIER INDICATED FOR
SATURDAY...SO HAVE REMOVED ALL MENTION OF RAIN EXCEPT FOR THE FAR SE
INCLUDING AOH. AMOUNTS WILL BE LIGHT. WILL KEEP SUNDAY THROUGH
WEDNESDAY DRY WITH TEMPS NEAR NORMAL. CONSENSUS OF ECMWF...CANADIAN
AND MFR WAS TO DEVELOP A DEEP TROF ALONG THE WEST COAST WITH A
WEAKER SYSTEM OVER THE NE CONUS. THE ECMWF DOES BRING MORE ENERGY IN
THE MID MISSISSIPPI VALLEY THAN THE OTHER MODELS. THE CANADIAN
ENSEMBLES FROM LAST NIGHT REFLECTED THE MODEL CONSENSUS. WITH THIS
PATTERN...AMOUNT AND TIMING OF ENERGY EJECTED DURING THE FIRST HALF
OF NEXT WEEK FROM WESTERN TROF UNDER THE UPPER RIDGE OVER THE
CENTRAL CONUS STILL IN QUESTION. WILL THEREFORE KEEP FORECAST DRY
WITH TEMPS NEAR NORMAL.
&&
.IWX WATCHES/WARNINGS/ADVISORIES...
IN...NONE.
MI...NONE.
OH...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS BALTIMORE MD/WASHINGTON DC
AFDLWX 950 PM EST THU FEB 19 2004
WATER VAPOR LOOP SHOWS A WRAPPED UP STORM OVER THE ATLANTIC...WHILE
A RIDGE BUILDS OVERHEAD (WITH 500MB HEIGHT RISES OF 50-100M). A
TROUGH IS BEING CARVED OUT ACROSS THE ROCKIES...WHERE WAVES WERE
SPOTTED OVER KANSAS AND UTAH. 23Z SURFACE ANALYSIS PLACES A
SECONDARY COLD/STATIONARY FRONT SOUTH OF THE METRO AREA EAST TO OVER
THE OCEAN. THIS BOUNDARY BECOMES A WARM FRONT WEST OF THE
MOUNTAINS...AS IT STRETCHES WEST TO AN INVERTED TROUGH OVER THE
SOUTHERN PLAINS. HIGH PRESSURE CENTERS WERE LOCATED ACROSS THE
HUDSON BAY AND FLORIDA.
EXPECT THIS BOUNDARY TO REMAIN CLOSE TO ITS CURRENT POSITION...OR
SLOWLY SAG SOUTHWARD DUE TO THE WEAK PRESSURE GRADIENT AS THE LAST
OF THE PRESSURE RISES AFFECTS THE AREA EARLY OVERNIGHT.
THEREFORE...EXPECT A SHARP NOCTURNAL INVERSION TO FORM OVERNIGHT
ACROSS THE NORTHEAST HALF OF THE FORECAST AREA...WHILE THE SOUTHWEST
HALF REMAINS BETTER MIXED (ESPECIALLY THE HIGHER TERRAIN). THIS WILL
ALLOW TEMPERATURES TO COOL MUCH MORE EFFICIENTLY EAST OF THE BLUE
RIDGE THAN WEST (EVEN THE VALLEYS WEST OF THE BLUE RIDGE AND SOUTH
OF MRB SHOULD REMAIN BETTER MIXED AND WARMER). SIMILARLY...WINDS IN
THE EAST WILL REMAIN LIGHT AND VARIABLE...WHILE WINDS IN THE HIGHER
TERRAIN KEEPS A WSW BREEZE. WILL ADJUST TEMPERATURES WITH THIS IN
MIND.
CURRENT RELATIVE HUMIDITIES IN THE UPPER LEVELS (FROM 00Z KIAD
SOUNDING) SEEM ADEQUATE TO ALLOW UPPER LEVEL MOISTURE TO STREAM IN
FROM TIME TO TIME AS THE MIDLEVEL RIDGE AXIS CENTERS ITSELF OVER THE
MID ATLANTIC BY SUNRISE.
WARMED UP REALLY NICELY TODAY MIXING TO ALMOST 800MB (ACCORDING TO
AFTERNOON ACARS SOUNDINGS) WITH NICE DOWNSLOPE COMPONENT. TOMORROW
WE LOSE THIS DOWNSLOPE COMPONENT AS LOW LEVEL WINDS BACK TO THE
SOUTHWEST...BUT COMPENSATE FOR THIS WITH WARMING LOW LEVEL
TEMPERATURES (925MB TEMPERATURES FOR INSTANCE WARM FROM NEAR 6C AT
21Z TODAY TO 9C TOMORROW AT 21Z ACCORDING TO THE 18Z ETA). THUS
BELIEVE A GOOD BALLPARK TEMPERATURE FORECAST WILL BE
PERSISTENCE...EXCEPT MUCH WARMER TEMPERATURES IN THE MOUNTAINS AND A
BIT WARMER ACROSS THE NORTHERN SECTIONS. WILL ADJUST THESE
TEMPERATURES AS NEEDED.
THE STORM WHICH PASSED TO OUR EAST TUESDAY NIGHT HAS DEEPENED TO
966MB AND IS CURRENTLY APPROACHING NOVA SCOTIA AND
NEWFOUNDLAND...WITH BLIZZARD CONDITIONS (MODERATE TO HEAVY
SNOW...BLOWING SNOW WITH NEAR ZERO VISIBILITY...AND GUSTS OVER 50KT).
UPDATED GRIDS SENT...ZFP AND OTHER PRODUCTS OUT SHORTLY.
ROGOWSKI
&&
.LWX WATCHES/WARNINGS/ADVISORIES...
DC...NONE.
MD...NONE.
VA...NONE.
WV...NONE.
MARINE...NONE.
$$
AREA FORECAST DISCUSSION
NWS UPTON NY
AFDOKX 250 PM EST THU FEB 19 2004
.SHORT TERM...AS THE LOW LEVEL RIDGE AXIS APPROACHES THE REGION
...IDEAL CONDITIONS WILL LEAD TO STRONG RADIATIONAL COOLING
OVERNIGHT...BEFORE HIGH...THEN MID LEVEL CLOUDS ADVECT EAST ACROSS
THE REGION AFTER 06Z. I WILL LOWER THE MIN TEMPS SLIGHTLY ACROSS THE
SOUTH FORK OF LONG ISLAND...WHERE SOME FRESH SNOW COVER STILL
EXISTS.
&&
.MEDIUM RANGE THROUGH SAT NIGHT...OUR NEXT WEATHER MAKER IS ALREADY
ON THE HORIZON...AS A SFC LOW OVER THE SCNTRL U.S. MOVES NE TOWARD
THE GREAT LAKES. BKN HIGH THEN MID CLOUDS WILL ADVECT E GUIDED BY A
FLATTENING BROAD UPPER LEVEL RIDGE AFTER 06Z TONIGHT.
THERE ARE DIFFERENCES IN THE WAY THE LATEST OPERATIONAL FCST MODEL
RUNS HANDLE THE EVOLUTION OF THIS SYSTEM AS IT MOVES NE AND THE
DEVELOPMENT OF A SECONDARY LOW OVER THE HUDSON VALLEY-SOUTHERN NEW
ENGLAND AREA DURING SAT.
ALL FCST MODELS SHOW THE DEVELOPMENT OF A WARM FRONT ACROSS THE MID
ATLANTIC STATES DURING THE DAY FRI...WITH MOISTURE CONVERGENCE
DEVELOPING NORTH OF THIS BOUNDARY. I BELIEVE THAT THE GFS SOLUTION
IS TOO AGGRESSIVE IN DEVELOPING QPF ACROSS THE NORTHERN PART OF OUR
CWA BY 00Z SAT. TIME WILL BE NEEDED FOR A DEVELOPING E FLOW TO
MOISTEN THE LOWER ATMOSPHERE. I HAVE NO PLANS TO INTRODUCE POPS
DURING THE DAY FRI.
HOWEVER...AS THIS BOUNDARY PROGRESSES SLOWLY NORTH TOWARD THE
REGION...SFC WINDS NW AND N OF NYC WILL DECOUPLE...ALLOWING SFC
TEMPS TO FALL TO AT OR BELOW 32 DEGS...LEADING TO THE DEVELOPMENT OF
FREEZING RAIN.
A WINTER WEATHER ADVISORY FOR FREEZING RAIN WILL LIKELY BE NEEDED
MAINLY BETWEEN 06Z AND 12Z SAT FOR MOST OF THE LOWER HUDSON
VALLEY...WESTERN PASSAIC...NW BERGEN AND NORTHERN FAIRFIELD AND NEW
HAVEN COUNTIES. STAY TUNED.
AS THE SECONDARY LOW FORMS NORTH OF THE REGION...SUBSIDENCE WILL
DEVELOP...RESULTING IN THE QUICK DEVELOPMENT OF A DRY SLOT...WHICH
WILL CUT OFF PRECIP EARLIER THAN PREVIOUSLY FCST...BY SAT EVENING.
A BRISK W-NW WIND FLOW WILL DEVELOP AS THIS SYSTEM LIFTS NE SAT
NIGHT AND SUN.
&&
.AVIATION....AVIATION...VFR THROUGH 18Z FRI. HOWEVER...FRONTAL
BOUNDARY DROPPED SOUTH THROUGH NYC AREA BETWEEN 16Z-17Z JUST AS THIS
MORNING/S CIGS BEGAN TO SCATTER OUT...AND RESULTANT VERTICAL MIXING
HAS BROUGHT STRONGER WINDS DOWN FROM ALOFT. LOCAL ACARS SOUNDINGS AT
16Z SHOWED 35-40 KT AT THE TOP OF THE MIXED LAYER...WILL FORECAST
GUSTS TO 30 KT UP UNTIL SUNSET. WINDS DIE DOWN TONIGHT WITH LOSS OF
DAYTIME HEATING AND AS HIGH PRESSURE BUILDS OVER THE AREA...WITH
HIGH AND MID CLOUDS MOVING IN AFTER MIDNIGHT.
&&
.MARINE...WILL CONTINUE THE SMALL CRAFT ADVISORY FOR THE COASTAL
WATERS THROUGH THIS EVENING MAINLY DUE TO SEAS HOWEVER WILL MENTION
OCCASION GUSTS TO 25 KNOTS AS WELL. THEREAFTER TRANQUIL INTO
SATURDAY WHEN SEAS AND WINDS INCREASE AHEAD OF COLD FRONT. LOOKING
FOR STRONG SMALL CRAFT ADVISORY CRITERIA FROM LATE IN THE DAY
SATURDAY INTO MONDAY. COULD WELL SEE GALE FORCE GUSTS HOWEVER FROM
SUNDAY THROUGH SUNDAY NIGHT WHICH WILL BE MENTIONED IN THE FORECAST
BUT AT THIS POINT WILL USE THE TERM OCCASIONAL
GUSTS.
&&
.HYDROLOGY...WE WILL NEED TO MONITOR AREA RIVERS FOR THE POTENTIAL
DEVELOPMENT OF ICE JAMS AS SOME MELTING OCCURS DURING THE DAY AND RE
FREEZING RECURS AT NIGHT. THE NEXT SYSTEM SLATED FOR FRI NIGHT INTO
SAT SHOULD RESULT IN ONLY ABOUT 1/4 INCH OF RAIN.
&&
.OKX WATCHES/WARNINGS/ADVISORIES...
CT...NONE.
NJ...NONE.
NY...NONE
MARINE...SMALL CRAFT ADVISORY FOR...ANZ355-353-350.
$$
GC