AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
418 AM CST SAT NOV 15 2008
.DISCUSSION...
317 AM CST
A LARGE COLD AIR MASS WILL MOVE EAST ACROSS THE REGION OF NORTH
CENTRAL ILLINOIS...NORTHEAST ILLINOIS AND NORTHWEST INDIANA TODAY.
TODAY THROUGH MONDAY....A BIG AIR MASS OF CONTINENTAL POLAR AIR
IS EXPECTED TO BE OVER THE GREAT LAKES AND OHIO VALLEY TODAY. THIS
AIR MASS IS CHARACTERIZED BY INSTABILITY BELOW 850 MB AND AN
INVERSION ABOVE 850 MB. SOME LIGHT SNOW SHOWERS OR FLURRIES MAY
OCCUR IN THE SURFACE TO 850 MB LAYER TODAY. WE WILL FORECAST LOWER
TEMPERATURES TODAY THROUGH SUNDAY NIGHT. A LARGE AMPLITUDE 500 MB
WAVE TROUGH WILL MOVE ACROSS THE GREAT LAKES TODAY THROUGH SUNDAY
MORNING. THIS LARGE WAVE WILL BE FOLLOWED BY A SHORT WAVE TROUGH
MOVING ACROSS THE REGION DURING MONDAY. WE WILL FORECAST
SCATTERED LIGHT SNOW SHOWERS FOR MONDAY. THE FORECAST SOUNDING
OVER NORTHEAST ILLINOIS SHOW THE ATMOSPHERE WILL BE BELOW
FREEZING SUNDAY NIGHT AND MONDAY. WE USED THE GFS MODEL AND
LOCALLY RUN WRF_ARW MODEL FOR THE FORECAST.
TUESDAY THROUGH WEDNESDAY...A LARGE SURFACE HIGH IS FORECAST TO MOVE
INTO THE OHIO VALLEY TUESDAY THROUGH WEDNESDAY. WE EXPECT DRY
WEATHER WITH NIGHTTIME LOW TEMPERATURES IN THE 20S. THE HIGH
TEMPERATURES ARE EXPECTED TO BE IN THE 40S. WE USED THE GFS MODEL
FOR OUR FORECAST.
&&
.AVIATION...
1049 PM CDT
0600 UTC TAFS...MOST OF THE RAIN SHOWERS THAT WERE LINGERING
ACROSS EASTERN IOWA EARLIER THIS EVENING HAVE QUICKLY DISSIPATED
AS THE UPPER LEVEL FORCING MOVES SOUTH OF THE REGION. ACARS
SOUNDINGS OUT OF RFD AND ORD SHOW A FAIRLY POTENT INVERSION AT
ABOUT 5KFT...SO LIKELY WONT SEE MUCH IN THE WAY OF RAIN POTENTIAL
THROUGH THE MORNING. STILL HAVE AN OUTSIDE SHOT AT SOME SNOW
FLURRIES DURING THE DAY SATURDAY...BUT THESE LIKELY WOULD NOT
BRING DOWN VIS AT ALL AT THE TAF SITES.
MAIN CONCERNS REMAIN THE BOUNCING BACK AND FORTH FROM MVFR TO VFR
CIGS AND THE WINDS. CIGS SHOULD MAINLY BE HIGH END MVFR THROUGHOUT
MOST OF THE MORNING...WITH A FEW BRIEF SHOTS AT VFR THROUGH THE
EARLY MORNING HOURS. CIGS WILL GRADUALLY IMPROVE SATURDAY WITH
THEM EVENTUALLY REACHING VFR BY AFTERNOON. WINDS WILL CONTINUALLY
INCREASE IN SPEED OUT OF THE NORTH AND BACK NORTHWEST THROUGHOUT
THE DAY. AS THE SECONDARY COLD SURGE PUSHES INTO NORTHERN ILLINOIS
OVERNIGHT...WIND GUSTS INTO THE 20-30KT RANGE WILL BE POSSIBLE
THROUGHOUT MOST OF THE PERIOD.
EXPECT MAINLY MVFR CIGS THROUGHOUT WITH A FEW BREAKS TO VFR.
HALBACH
&&
.MARINE...
410 AM CST
LOW PRESSURE CONTINUES TO DEEPEN AS IT MOVES FROM THE LOWER TO THE
MID OHIO VALLEY EARLY THIS MORNING. THIS LOW IS FORECAST TO
CONTINUE THE DEEPENING PROCESS TODAY AND TONIGHT AS IT CONTINUES
UP THE OHIO VALLEY TODAY...AND ACROSS THE UPPER SAINT LAWRENCE
VALLEY BY SUNDAY MORNING. WHILE THE TIGHT PRESSURE GRADIENT
CURRENTLY ACROSS THE UPPER MISSISSIPPI VALLEY AND THE MID AND
LOWER MISSOURI VALLEY PROGRESSES EASTWARD OVER THE WESTERN GREAT
LAKES AND THE LOWER OHIO VALLEY LATER TODAY...IT APPEARS THAT THE
STRONGEST WINDS WILL OCCUR FROM THE MID MISSISSIPPI VALLEY EAST
INTO THE OHIO VALLEY WHERE THE GREATEST PRESSURE RISES HILL OCCUR
BEHIND THE LOW AND THE CENTER OF AN ANTICYCLONE SETTLING FROM THE
CENTRAL ROCKIES ACROSS THE SOUTHERN HIGH PLAINS.
NORTH WINDS WILL INCREASE OVER LAKE MICHIGAN LATER TODAY AS THE
MID/UPPER TROUGH AXIS SHIFTS EAST OF THE LAKE. STRONG LOW LEVEL
COLD ADVECTION TO SET IN ACROSS THE REGION BEHIND THE TROUGH WITH
LARGE LAKE SURFACE TO 850 HPA TEMPERATURE DIFFERENTIALS RESULTING
IN EFFICIENT MIXING FROM AT LEAST 2KM ABOVE THE SURFACE.
HOWEVER...FORECAST WINDS ALOFT ONLY SUPPORT MARGINAL GALE FORCE
WINDS FOR THIS AFTERNOON AND EVENING EVEN WITH EFFICIENT MOMENTUM
TRANSFER DOWN TO WATER LEVEL. LITTLE TO NO ISALLOBARIC WIND
COMPONENT TO THE WIND AS THE PRESSURE RISE CENTER PASSES WELL
SOUTH AND SOUTHEAST OF THE LAKE AS MENTIONED ABOVE.
TRS
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...GALE WARNING...LMZ080-LMZ261-LMZ362-LMZ364-LMZ366-LMZ563-LMZ565-
LMZ567-LMZ669-LMZ671-LMZ673-LMZ675-LMZ744-LMZ745-LMZ777-
LMZ779-LMZ868-LMZ870-LMZ872-LMZ874-LMZ876-LMZ878 UNTIL 6 AM
SUNDAY.
SMALL CRAFT ADVISORY...NEARSHORE WINTHROP HARBOR TO GARY IN UNTIL 6 AM
SUNDAY.
&&
$$
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
351 AM CST SAT NOV 15 2008
.DISCUSSION...
317 AM CST
A LARGE COLD AIR MASS WILL MOVE EAST ACROSS THE REGION OF NORTH
CENTRAL ILLINOIS...NORTHEAST ILLINOIS AND NORTHWEST INDIANA TODAY.
TODAY THROUGH MONDAY....A BIG AIR MASS OF CONTINENTAL POLAR AIR
IS EXPECTED TO BE OVER THE GREAT LAKES AND OHIO VALLEY TODAY. THIS
AIR MASS IS CHARACTERIZED BY INSTABILITY BELOW 850 MB AND AN
INVERSION ABOVE 850 MB. SOME LIGHT SNOW SHOWERS OR FLURRIES MAY
OCCUR IN THE SURFACE TO 850 MB LAYER TODAY. WE WILL FORECAST LOWER
TEMPERATURES TODAY THROUGH SUNDAY NIGHT. A LARGE AMPLITUDE 500 MB
WAVE TROUGH WILL MOVE ACROSS THE GREAT LAKES TODAY THROUGH SUNDAY
MORNING. THIS LARGE WAVE WILL BE FOLLOWED BY A SHORT WAVE TROUGH
MOVING ACROSS THE REGION DURING MONDAY. WE WILL FORECAST
SCATTERED LIGHT SNOW SHOWERS FOR MONDAY. THE FORECAST SOUNDING
OVER NORTHEAST ILLINOIS SHOW THE ATMOSPHERE WILL BE BELOW
FREEZING SUNDAY NIGHT AND MONDAY. WE USED THE GFS MODEL AND
LOCALLY RUN WRF ARW MODEL FOR THE FORECAST.
TUESDAY THROUGH WEDNESDAY...A LARGE SURFACE HIGH IS FORECAST TO MOVE
INTO THE OHIO VALLEY TUESDAY THROUGH WEDNESDAY. WE EXPECT DRY
WEATHER WITH NIGHTTIME LOW TEMPERATURES IN THE 20S. THE HIGH
TEMPERATURES ARE EXPECTED TO BE IN THE 40S. WE USED THE GFS MODEL
FOR OUR FORECAST.
&&
.AVIATION...
1049 PM CDT
0600 UTC TAFS...MOST OF THE RAIN SHOWERS THAT WERE LINGERING
ACROSS EASTERN IOWA EARLIER THIS EVENING HAVE QUICKLY DISSIPATED
AS THE UPPER LEVEL FORCING MOVES SOUTH OF THE REGION. ACARS
SOUNDINGS OUT OF RFD AND ORD SHOW A FAIRLY POTENT INVERSION AT
ABOUT 5KFT...SO LIKELY WONT SEE MUCH IN THE WAY OF RAIN POTENTIAL
THROUGH THE MORNING. STILL HAVE AN OUTSIDE SHOT AT SOME SNOW
FLURRIES DURING THE DAY SATURDAY...BUT THESE LIKELY WOULD NOT
BRING DOWN VIS AT ALL AT THE TAF SITES.
MAIN CONCERNS REMAIN THE BOUNCING BACK AND FORTH FROM MVFR TO VFR
CIGS AND THE WINDS. CIGS SHOULD MAINLY BE HIGH END MVFR THROUGHOUT
MOST OF THE MORNING...WITH A FEW BRIEF SHOTS AT VFR THROUGH THE
EARLY MORNING HOURS. CIGS WILL GRADUALLY IMPROVE SATURDAY WITH
THEM EVENTUALLY REACHING VFR BY AFTERNOON. WINDS WILL CONTINUALLY
INCREASE IN SPEED OUT OF THE NORTH AND BACK NORTHWEST THROUGHOUT
THE DAY. AS THE SECONDARY COLD SURGE PUSHES INTO NORTHERN ILLINOIS
OVERNIGHT...WIND GUSTS INTO THE 20-30KT RANGE WILL BE POSSIBLE
THROUGHOUT MOST OF THE PERIOD.
EXPECT MAINLY MVFR CIGS THROUGHOUT WITH A FEW BREAKS TO VFR.
HALBACH
&&
.MARINE...
1225 PM CST
COLD FRONT TRAILING SOUTHWARD FROM LOW NEAR JAMES BAY HAS CLEARED
LAKE MICHIGAN...RESULTING IN PREVAILING NORTHWEST FLOW. PRELIMINARY
THOUGHT IS THAT GALE WARNING FOR SATURDAY WILL BE CONTINUED AS
CURRENTLY FORECAST. A COMBINATION OF LOW PRESSURE DEVELOPMENT AND
DEEPENING TO EAST OF LAKES...AND REINFORCING SURGE OF COLD AIR
EXPECTED TO ARRIVE LATER TONIGHT...SHOULD CAUSE WINDS TO GUST HIGHER
THAN GUIDANCE FORECAST...AND REACH 35 KNOT CRITERIA. HOWEVER...WITH
STRONGEST PRESSURE RISES AND AXIS OF MID LEVEL JET STREAM WINDS
HEADING SOUTH OF LAKE...EXPECT ONLY A MINIMAL GALE SITUATION.
NORTHWEST WINDS TO REMAIN ELEVATED INTO SATURDAY NIGHT...THEN SLOWLY
DECREASE AS CORE OF COLD AIR PASSES ACROSS LAKE...FOLLOWED BY
BACKING INTO THE WEST SOUTHWEST BY EARLY SUNDAY. SOUTHWEST FLOW TO
CONTINUE SUNDAY AHEAD OF NEXT COLD FRONT FORECAST TO SWEEP ACROSS
LAKE SUNDAY NIGHT.
MERZLOCK
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...GALE WARNING...LMZ080-LMZ261-LMZ362-LMZ364-LMZ366-LMZ563-LMZ565-
LMZ567-LMZ669-LMZ671-LMZ673-LMZ675-LMZ744-LMZ745-LMZ777-
LMZ779-LMZ868-LMZ870-LMZ872-LMZ874-LMZ876-LMZ878 UNTIL 6 AM
SUNDAY.
SMALL CRAFT ADVISORY...NEARSHORE WINTHROP HARBOR TO GARY IN UNTIL 6 AM
SUNDAY.
&&
$$
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
1049 PM CST FRI NOV 14 2008
.DISCUSSION...
257 PM...STILL SOME LIGHT RAIN SHOWERS/SPRINKLES ACROSS PARTS OF THE
EASTERN CWA WITH ANOTHER AREA OF RAIN MOVING SOUTHEAST ACROSS IOWA
ASSOCIATED WITH A SHORTWAVE WHICH IS MOVING ALONG THE BASE OF THE
UPPER TROF. THE BULK OF THIS ACTIVITY APPEARS TO MOVE JUST SOUTH OF
THE CWA...PERHAPS CLIPPING THE WESTERN/SOUTHWESTERN COUNTIES. WILL
KEEP LIKELY POPS THERE BUT JUST CHANCE POPS ELSEWHERE AND PRECIP
TYPE TO REMAIN RAIN. BUT TOWARD MORNING...ANY LINGERING LIGHT PRECIP
COULD MIX WITH A FEW SNOWFLAKES.
COLD AIR BEGINS TO SPREAD OVER THE REGION BY SATURDAY MORNING AND
MODELS SHOW YET ANOTHER SHORTWAVE RIDING NORTHEAST ACROSS INDIANA
AND THIS IN ADDITION TO NORTHERLY FLOW OFF THE LAKE SHOULD BE ENOUGH
TO GENERATE SOME SNOW SHOWERS ACROSS THE EASTERN THIRD OR SO OF THE
CWA. HAVE MAINTAINED JUST CHANCE POPS BUT WITH A FEW TENTHS OF SNOW
ACCUMULATION IN THE GRIDS...WITH SCATTERED FLURRIES ELSEWHERE.
SFC RIDGE IS A TAD FASTER NOW MOVING ACROSS THE AREA BY SUNDAY
MORNING. SO WHILE LOWS SUNDAY MORNING WILL LIKELY BE QUITE CHILLY IN
THE 20S...SUNDAY MAY END UP WARMING ABOVE EXPECTED VALUES...PERHAPS
LOWER 40S. HOWEVER...ANOTHER CLIPPER-LIKE SYSTEM QUICKLY MOVES
ACROSS THE LAKES SUNDAY NIGHT AND THE MODELS HAVE BEEN VERY
CONSISTENT WITH THE EXTENT OF COLD AIR ARRIVING MONDAY AND MONDAY
NIGHT...NOW SHOWING 850MB TEMPS AS LOW AS -14C BY TUESDAY MORNING.
WIND DIRECTION OFF LAKE MICHIGAN WILL BE CRITICAL DURING THIS TIME
FOR POSSIBLE LAKE EFFECT SNOW ACROSS LAKE/PORTER COUNTIES IN
NORTHWEST INDIANA. HAVE MAINTAINED CHANCE POPS FOR NOW AND ANY
ACCUMULATION MAY BE JUST EAST OF PORTER BUT WILL CERTAINLY NEED TO
BE WATCHED AS THIS TIME PERIOD APPROACHES.
PROGRESSIVE PATTERN CONTINUES WITH ANOTHER RIDGE/HIGH PRESSURE
MOVING ACROSS THE REGION TUESDAY AND TUESDAY NIGHT. DIFFICULT TO
DETERMINE FROM THIS DISTANCE WHETHER HIGHS WEDNESDAY WILL MANAGE A
RUN INTO THE 40S BEFORE COLD AIR ARRIVES AS ANOTHER WEAK CLIPPER
MOVES ACROSS THE REGION DURING THIS TIME...BRINGING ANOTHER SURGE
OF COLD AIR. 12Z GFS HAS BACKED OFF SUGGESTING THE COLDEST OF THE
AIR MAY STAY NORTH OF THE AREA. ECMWF IS CONSISTENT SHOWING MUCH
COLDER AIR ARRIVING BY THURSDAY AND HAVE FOLLOWED ITS TREND WITH
LOWS IN THE TEENS BY NEXT FRIDAY AND SATURDAY MORNINGS. CMS
&&
.AVIATION...
1049 PM CDT
0600 UTC TAFS...MOST OF THE RAIN SHOWERS THAT WERE LINGERING
ACROSS EASTERN IOWA EARLIER THIS EVENING HAVE QUICKLY DISSIPATED
AS THE UPPER LEVEL FORCING MOVES SOUTH OF THE REGION. ACARS
SOUNDINGS OUT OF RFD AND ORD SHOW A FAIRLY POTENT INVERSION AT
ABOUT 5KFT...SO LIKELY WONT SEE MUCH IN THE WAY OF RAIN POTENTIAL
THROUGH THE MORNING. STILL HAVE AN OUTSIDE SHOT AT SOME SNOW
FLURRIES DURING THE DAY SATURDAY...BUT THESE LIKELY WOULD NOT
BRING DOWN VIS AT ALL AT THE TAF SITES.
MAIN CONCERNS REMAIN THE BOUNCING BACK AND FORTH FROM MVFR TO VFR
CIGS AND THE WINDS. CIGS SHOULD MAINLY BE HIGH END MVFR THROUGHOUT
MOST OF THE MORNING...WITH A FEW BRIEF SHOTS AT VFR THROUGH THE
EARLY MORNING HOURS. CIGS WILL GRADUALLY IMPROVE SATURDAY WITH
THEM EVENTUALLY REACHING VFR BY AFTERNOON. WINDS WILL CONTINUALLY
INCREASE IN SPEED OUT OF THE NORTH AND BACK NORTHWEST THROUGHOUT
THE DAY. AS THE SECONDARY COLD SURGE PUSHES INTO NORTHERN ILLINOIS
OVERNIGHT...WIND GUSTS INTO THE 20-30KT RANGE WILL BE POSSIBLE
THROUGHOUT MOST OF THE PERIOD.
EXPECT MAINLY MVFR CIGS THROUGHOUT WITH A FEW BREAKS TO VFR.
HALBACH
&&
.MARINE...
1225 PM CST
COLD FRONT TRAILING SOUTHWARD FROM LOW NEAR JAMES BAY HAS CLEARED
LAKE MICHIGAN...RESULTING IN PREVAILING NORTHWEST FLOW. PRELIMINARY
THOUGHT IS THAT GALE WARNING FOR SATURDAY WILL BE CONTINUED AS
CURRENTLY FORECAST. A COMBINATION OF LOW PRESSURE DEVELOPMENT AND
DEEPENING TO EAST OF LAKES...AND REINFORCING SURGE OF COLD AIR
EXPECTED TO ARRIVE LATER TONIGHT...SHOULD CAUSE WINDS TO GUST HIGHER
THAN GUIDANCE FORECAST...AND REACH 35 KNOT CRITERIA. HOWEVER...WITH
STRONGEST PRESSURE RISES AND AXIS OF MID LEVEL JET STREAM WINDS
HEADING SOUTH OF LAKE...EXPECT ONLY A MINIMAL GALE SITUATION.
NORTHWEST WINDS TO REMAIN ELEVATED INTO SATURDAY NIGHT...THEN SLOWLY
DECREASE AS CORE OF COLD AIR PASSES ACROSS LAKE...FOLLOWED BY
BACKING INTO THE WEST SOUTHWEST BY EARLY SUNDAY. SOUTHWEST FLOW TO
CONTINUE SUNDAY AHEAD OF NEXT COLD FRONT FORECAST TO SWEEP ACROSS
LAKE SUNDAY NIGHT.
MERZLOCK
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...GALE WARNING...LMZ080-LMZ261-LMZ362-LMZ364-LMZ366-LMZ563-LMZ565-
LMZ567-LMZ669-LMZ671-LMZ673-LMZ675-LMZ744-LMZ745-LMZ777-
LMZ779-LMZ868-LMZ870-LMZ872-LMZ874-LMZ876-LMZ878...6 AM
SATURDAY TO 6 AM SUNDAY.
SMALL CRAFT ADVISORY...LMZ740-LMZ741-LMZ742-LMZ743...4 AM
SATURDAY TO 6 AM SUNDAY.
&&
$$
AREA FORECAST DISCUSSION...UPDATED
NWS MARQUETTE MI
1017 PM EST SUN NOV 16 2008
.UPDATE...
WATER VAPOR IMAGERY AND RUC ANALYSIS SHOW SHORTWAVE DROPPING SSE
THRU ERN MANITOBA WITH ANOTHER SUBTLE SHORTWAVE JUST AHEAD OF IT NRN
ONTARIO. CWPL SOUNDING SHOWS THE IMPACT THESE SHORTWAVES WILL HAVE.
12Z SOUNDING SHOWED SHARP INVERSION BASED AT 850MB/4.4KFT MSL WHILE
00Z SOUNDING SHOWED INVERSION BASED AT 770MB/7KFT MSL. SO...THESE
FEATURES WILL GIVE LES A SOLID BOOST LATE TONIGHT THRU AT LEAST MON
MORNING AS THEY HEAD SSE. DESPITE CONSIDERABLY LESS SHEAR IN THE
CONVECTIVE LAYER THAN LAST EVENING PER KMQT VAD WIND PROFILE...
ONGOING LES OVER SCNTRL LAKE SUPERIOR INTO UPPER MI IS SURPRISINGLY
VERY DISORGANIZED...MUCH LIKE LAST EVENING. OUT WEST...POCKET OF DRY
WELL MIXED LAYER AIR PER AFTN TAMDAR SOUNDING FROM CYQT HAS HAD A
STRONG NEGATIVE IMPACT ON LES. SFC OBS/WEB CAMS SUGGEST -SHSN HAVE
BEEN VERY LIGHT DURING THE LATE AFTN INTO EARLY EVENING. MORE
RECENTLY...RADAR IMAGERY FROM KDLH IS BEGINNING TO SHOW SOME LES
BANDING INTO FAR WRN GOGEBIC COUNTY...SO LES IS PICKING UP IN THAT
AREA NOW.
GOING FCST APPEARS TO HAVE A GOOD HANDLE ON THE INCREASING LES
REGIME OVERNIGHT INTO MON. SO...FOR THE MOST PART...ONLY MINOR
CHANGES ARE NEEDED. ONE SIGNIFICANT CHANGE WILL BE TO RUN SRN
SCHOOLCRAFT LES ADVY THRU 12Z AS WIND FLOW WILL STILL SUPPORT THE
POTENTIAL OF STRONGER LES BANDS REACHING THAT AREA THRU THE
OVERNIGHT. ALSO...INCREASED POPS/SNOW AMOUNTS IN NRN DELTA COUNTY
(NORTH AND EAST OF RAPID RIVER) OVERNIGHT INTO MON AS THE DOMINANT
BAND THAT WILL BE AFFECTING WRN ALGER/ERN MARQUETTE COUNTIES SHOULD
EXTEND THAT FAR S GIVEN THE LIFTING INVERSION.
&&
.SYNOPSIS... ISSUED AT 405 PM EST
DEEP TROUGH ALOFT CENTERED NEAR JAMES BAY CONTINUES TO FEED COLD AND
MOIST AIR ACROSS THE GREAT LAKES. LK EFFECT SNOWS ARE FLYING...MOST
NMRS BTWN SHOT POINT IN FAR ERN MARQUETTE COUNTY TO NEWBERRY.
DAYTIME ACCUMS WITHIN THE HEAVIER SNOW SHOWERS IN THIS AREA HAVE
MAXED OUT BTWN 3-5 INCHES. DESPITE MOISTURE TO H7 AND SUFFICIENT
INSTABILITY WITH DELTA T/S OVR 15C...SHIFTING WINDS HAVE NOT ALLOWED
DOMINANT BAND TO SET UP AND PERSIST IN ANY ONE SPOT. ELSEWHERE ALONG
LAKE SUPERIOR...LK EFFECT IS BENIGN AS DEEP MOISTURE IS LACKING
ABOVE 5KFT AS THE UPR LAKES IS BTWN SHORTWAVES THAT ARE ROTATING
THROUGH THE REGION. NEXT WAVE OF IMPORTANCE IS DIVING SOUTH ACROSS
NORTHERN MANITOBA. ARRIVAL OF THIS WAVE LATE TONIGHT INTO MONDAY
MORNING SHAPRENS LAKE INDUCED TROUGH AND WILL INTENSIFY THE LK
EFFECT SNOW SHOWERS. LONGWAVE TROUGH AND COOL TEMPS PERSIST THROUGH
MUCH OF UPCOMING WEEK...KEEPING LK EFFECT GOING. ANOTHER SHORTWAVE
THAT MAY ALLOW FOR AN INCREASE IN THE LK EFFECT IS CURRENTLY OVR NRN
BRITISH COLUMBIA. THIS WAVE IS PROGGED TO AFFECT THE UPR LAKES
WEDNESDAY INTO THURSDAY.
&&
.SHORT TERM (TONIGHT AND MONDAY)... ISSUED AT 405 PM EST
GFS AND THE HIGHER RESOLUTION MODELS REMAIN AT ODDS WITH HOW THE LOW
LEVEL WINDS BEHAVE IN THE WAKE OF THE SHORTWAVE LATE TONIGHT INTO
MONDAY. FOR THE LAST FEW DAYS...THE GFS HAS REMAINED WITH MORE OF A
NW WIND WHILE THE HIGHER RESOLUTION NAM/LOCAL WRF/RUC13 POINT TO
SHARPTER TROUGHING AND A NORTH WIND. NOT A BIG DIFFERENCE...BUT THE
IMPLICATIONS ON THE FORECAST ARE LARGE. CANADIAN GEM IS A COMPROMISE
AND IS FAVORED BY HPC AND LEANED THAT WAY FOR THE GRIDS. NW LOW
LEVEL FLOW KEEPS MODERATE LK EFFECT INTO ALGER AND NORTHERN PORTION
OF SCHOOLCRAFT THIS EVENING. LOW LEVEL CONVERGENCE WILL STRENGTHEN
LATER THIS EVENING INTO THE OVERNIGHT OVR ALGER COUNTY AS WINDS OVR
CNTRL CWA BACK WITH BLYR COOLING/DEVELOPING LAND BREEZE. IN THE WRN
CWA...LK EFFECT SHOULD PICK UP (UP TO 4" OF ACCUMULATION) AS
PERSISTENT MOIST NW FLOW THROUGH H85 IS SUPPLEMENTED BY ADDITIONAL
MOISTURE TO H7 COMING IN AHEAD OF THE SHORTWAVE AND AS H85 TEMPS
COOL.
NW FLOW CONTINUES THROUGH EARLY MONDAY BUT THEN AS SHORTWAVE PASSES
THROUGH...LOW LEVEL WINDS BECOME NRLY. REGIONAL GEM SUGGESTS PERIOD
OF N WINDS OCCURS BTWN 15Z AND 21Z. WITH THE WIND SHIFT...EXPECT
SNOW SHOWERS TO INCREASE OVR FAR WEST AND ALSO INTO ERN MARQUETTE
COUNTY. REGIONAL GEM SOUNDINGS INDICATE THAT BY TIME WINDS BECOME
NORTH IN THE FAR WEST CWA...THE DEEPER MOISTURE IS LIMITED...SO
HEAVY SNOW SHOULD BE FAIRLY SHORT LIVED THERE. IT WILL BE CLOSE
THOUGH. DECIDED TO KEEP A HIGH END LES ADVY FOR GOGEBIC INTO
ONTONAGON. MEANWHILE...FM WESTERN HALF OF ALGER INTO ERN MARQUETTE
COUNTY...SOUNDINGS SHOW IMPRESSIVE INSTABILITY WITH ABUNDANT
MOISTURE TO H7-H6 AND H85/H7 TEMPS OF -13C/-22C RESULTING IN LK
INDUCED CAPES EXCEEDING 800J/KG. SNOWFALL RATES WITHIN THE MAIN
CONVERGENCE BAND IN THIS AREA WILL EXCEED 1"/HR. HAVE DECIDED TO
KEEP THE ADVY FOR MARQUETTE COUNTY...WITH EXPECTATION THAT PERIOD OF
NRLY WINDS/HEAVIEST SNOW WILL BE SHORT ENOUGH TO PROHIBIT WARNING
AMOUNTS. OBVIOUSLY...IF THE MODELS THAT SHOW QUICKER DEPICTION OF
WINDS VEERING TO THE NORTH COME TO FRUITION...THEN A WARNING WOULD
BE NEEDED FOR MARQUETTE. WARNING AMOUNTS FOR WRN ALGER SEEM A NEAR
CERTAINTY. BY LATE MONDAY AFTN...HEAVIEST SNOW WILL SHIFT INTO ALGER
COUNTY AS WINDS BEGIN TO BACK IN THE WAKE OF THE SHORTWAVE.
.LONG TERM DISCUSSION (MON NGT THRU SUN)...
ONGOING LES IN THE N WIND SN BELTS ON MON WL BEGIN TO DRIFT INTO
AREAS FVRD BY NW WINDS ON MON NGT OVER THE W AND E OF MQT ON TUE AS
THE LLVL FLOW GRDLY BACKS MORE NW WITH THE APRCH OF A HI PRES RDG
THAT IS FCST TO MOVE NEAR MPX BY 12Z TUE UNDER SLOWLY RISING HGTS.
AS SUBSIDENCE INVRN GRDLY SINKS W-E MON NGT...EXPECT THE HEAVIEST
LES TO DIMINISH AS WELL. MODEL DISCREPANCIES NOTED OVER THE LAST FEW
DAYS PERSIST WITH THE GFS BEING MORE PROGRESSIVE THAN THE HIER RES
MODELS LIKE THE NAM/CNDN/LOCAL WRF-ARW IN BACKING THE FLOW AND
LOWERING THE INVRN BASE...ESPECIALLY ON MON NGT. CONSIDERING THE
BETTER LLVL RESOLUTION OF THE NAM/CNDN/WRF-ARW...WL TEND TOWARD THE
SCENARIO DEPICTED BY THAT GUIDANCE...WHICH WOULD INDICATE GOING
HEADLINES MIGHT NEED TO EVENTUALLY BE EXTENDED 6-12 HRS. UNTIL
GUIDANCE BECOMES CLEARER...WL HOLD OFF ON CHANGING HEADLINE TIMES.
THE NAM/CNDN ACTUALLY BECOME FASTEST THAN THE GFS TO RAISE THE MSLP
ON TUE AND PUSH THE RDG AXIS TO THE E. EVEN THOUGH THE INVRN BASE
LOWERS STEADILY AS SHOWN ON FCST SDNGS FM BOTH MODELS (ALBEIT AT
DIFFERENT RATES)...TEMPS WITHIN THE MIXED LYR BLO THE INVRN ARE LO
ENUF (H85 TEMPS ARND -15C AT 06Z TUE) TO FAVOR DENDRITIC SN GROWTH
ALMOST TO THE TIME OF ARRIVAL OF RDG AXIS. SO WL APPROXIMATE SN AMTS
WITH A HIGH SN/WATER RATIO AOA 20:1. BY LATE TUE...THE FLOW IS
PROGGED TO BE W ENUF SO THAT THE ONLY LINGERING LES SHOULD BE OVER
THE KEWEENAW AND E OF P53.
AS THE RDG AXIS SHIFTS TO THE E ON TUE NGT AND A SHRTWV EMBEDDED
WITHIN THE NW FLOW ALF BTWN UPR RDG OVER THE ROCKIES AND TROF OVER
THE E APRCHS THE FA...STRONG WAD AS EVIDENCED BY VEERING WINDS WITH
HGT AND SHARP ISENTROPIC LIFT ON THE 280K-295K SFCS (H85-6) IS
PROGGED TO DVLP OVER UPR MI. ALTHOUGH FCST SNDGS SHOW VERY DRY
LLVLS...BOTH THE GFS/NAM TEND TO SATURATE THE LLVLS OVER THE NW FA
ENUF TO WARRANT INCLUSION OF CHC POP WHERE H85-7 FGEN IS FCST. BUT
PCPN AMTS WL BE LIMITED BY LACK OF SGNFT ABSOLUTE MSTR INFLOW. AS
THE SFC LO/ATTENDANT PRES TROF APRCH THE UPR GRT LKS...HAVE SPRD CHC
POPS ACRS THE ENTIRE FA. TENDED TO USE A BLEND OF THE 12Z CNDN/NAM
MODELS AS THIS NEW GUIDANCE IS BETTER IN LINE WITH NCEP PREFERRED
00Z ECMWF ON HANDLING OF SHRTWV. WITH BETTER 280-295K ISENTROPIC
LIFT/H85 QVECTOR CNVGC FCST OVER THE NE FA CLOSER TO SHRTWV
TRACK/DOWNWIND OF SOME MOISTENING OFF LK MI...WENT WITH THE HIER
POPS ACRS NRN LK SUP/THE ERN FA COUNTIES.
IN THE MEDIUM/EXTENDED PD...NCEP INDICATED A PREFERENCE FOR THE 0Z
ECMWF FCST...WHICH IS GENERALLY A BIT MORE PROGRESSIVE THAN RECENT
GFS FCSTS. COLD AIR INFUSION IN THE WAKE OF SHRTWV (00Z ECMWF SHOWS
H85 TEMPS FALLING AS LO AS -17C BY 00Z FRI OVER WRN LK SUP)
RESPONSIBLE FOR PCPN CHCS ON WED WL BRING A SHOT OF LES WED NIGT
INTO FRI AS GUSTY N WINDS/PSBL GALES ON LK SUP BTWN HI PRES OVER SE
CAN AND LO PRES TO THE E DRAG THE COLDER AIR INTO THE UPR LKS. LES
ADVYS/WRNGS WL LIKELY BE NEEDED FOR THIS EVENT AT SOME POINT...WL
HIGHLIGHT IN THE HWO FOR NOW. THE LES WL DIMINISH FRI/FRI NGT WITH
ARRIVAL OF HI PRES RDG...BUT WAD AHEAD OF NEXT SHRTWV/SFC LO PRES
EXPECTED TO MOVE E TOWARD THE UPR LKS WL BEGIN TO IMPACT THE FA AS
EARLY AS FRI NGT. WL CARRY CHC POPS FOR SOME -SN THRU THE DAY ON
SAT...WITH THE HIER POPS ACRS THE NRN FA CLOSER TO LO PRES TRACK
FCST BY BULK OF GUIDANCE ACRS NRN LK SUP/ADJOINING ONTARIO. THEN LO
CHC POPS FOR SOME LES ON SUN WITH SOME CAD IN THE WAKE OF THE LO.
TEMPS AOB NORMAL INTO FRI WL RECOVER CLOSER TO NORMAL OVER THE
WEEKEND.
&&
.AVIATION (FOR THE 00Z TAF ISSUANCE)...
AT KCMX...EXPECT VFR/OCCASIONAL MVFR CONDITIONS TO PREVAIL THRU THE
EVENING UNDER RELATIVELY DRY WELL MIXED BOUNDARY LAYER. OVERNIGHT...
APPROACHING UPPER LEVEL DISTURBANCE WILL PROVIDE MORE FAVORABLE
CONDITIONS FOR LAKE EFFECT -SHSN AS MOISTURE DEPTH INCREASES AND
INVERSION LIFTS. PREVAILING MVFR CONDITIONS WILL DEVELOP OVERNIGHT
WITH DOWNWARD TREND TO IFR MON MORNING AS STRENGTHENING LOW-LEVEL
CONVERGENCE FURTHER ENHANCES -SHSN. LIMITED IMPROVEMENT POSSIBLE
LATER MON AFTN AS LOW-LEVEL CONVERGENCE WEAKENS AND UPPER LEVEL
DISTURBANCE DEPARTS.
AT KSAW...DOWNSLOPING NW FLOW SHOULD RESULT IN PREVAILING VFR
CONDITIONS THRU MUCH OF THE NIGHT. EARLY MON MORNING...APPROACHING
UPPER LEVEL DISTURBANCE WILL PROVIDE MORE FAVORABLE CONDITIONS FOR
LAKE EFFECT -SHSN AS MOISTURE DEPTH INCREASES AND INVERSION LIFTS.
PREVAILING MVFR CONDITIONS SHOULD DEVELOP BEFORE DAYBREAK WITH
DOWNWARD TREND TO IFR MID TO LATE MON MORNING. DOMINANT/INTENSE
SNOW BAND ON A CONVERGENCE ZONE SHIFTING SW OVER SRN LAKE SUPERIOR
SHOULD IMPACT KSAW AT SOME POINT MON AFTN (PROBABLY EARLY AFTN BASED
ON LATEST GUIDANCE). LIFR CONDITIONS WILL BE LIKELY WITH THIS BAND.
ONLY LIMITED IMPROVEMENT TO IFR EXPECTED AFTER THE BAND PASSES AS
FAVORABLE UPSLOPING NRLY WIND WILL CONTINUE.
&&
.MARINE (FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE)...
WINDS WILL STAY NORTH TO NORTHWEST UP TO 30 KNOTS THROUGH MONDAY
BEFORE DIMINISHING AS HIGH PRESSURE BRIEFLY BUILDS IN. A COLD FRONT
WILL MOVE THROUGH ON WEDNESDAY WITH SHARPLY COLDER AIR BEHIND IT. N
GALES ARE EXPECTED WED NIGHT INTO THU NIGHT IN THE SHARP PRESSURE
GRADIENT BETWEEN THE DEPARTING TROUGH OF LOW PRESSURE AND INCOMING
HIGH PRESSURE CENTER OVER THE NORTHERN PLAINS. OUTSIDE OF THIS PERIOD
EXPECT WINDS UP TO 30 KNOTS.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
LAKE EFFECT SNOW WARNING UNTIL 1 AM EST TUE MIZ006-085.
LAKE EFFECT SNOW ADVY UNTIL 5 AM EST MON MIZ007.
LAKE EFFECT SNOW ADVY FROM 4 AM MON TO 1 AM EST TUE MIZ005.
LAKE EFFECT SNOW ADVY UNTIL 7 PM EST /6 PM CST/ MON MIZ002-009.
LAKE EFFECT SNOW ADVY UNTIL 7 AM EST MON MIZ014.
LAKE SUPERIOR...NONE.
LAKE MICHIGAN...NONE.
$$
UPDATE...ROLFSON
SYNOPSIS...JLA
SHORT TERM...JLA
LONG TERM...KC
AVIATION...ROLFSON
MARINE...JLA
AREA FORECAST DISCUSSION...UPDATE
NWS MARQUETTE MI
1040 AM EST SAT NOV 15 2008
UPDATED FOR 18Z TAF ISSUANCE
.UPDATE...
MADE SOME MINOR CHGS TO GOING FCST BASED ON RADAR TRENDS/12Z NAM AND
LOCAL HI RES MODEL OUTPUT. CUT POPS OVER LUCE COUNTY WITH TOO MUCH
OF A NLY FLOW TO ALLOW FOR SGNFT LES THERE. ALSO TENDED TO LIMIT THE
MENTION OF RA MIXED WITH THE PCPN BASED ON CURRENT DWPTS/LOWER WBZ
HGT. OVERALL...A SUB-ADVY LES EVENT FOR NNW FLOW IS STILL IN THE
WORKS WITH LARGER SCALE SUBSIDENCE MAINTAINING AN INVRN BASE ARND 5K
FT AS SHOWN ON 15Z TAMDAR SDNGS FM RHI/SAW AND TENDING TO LIMIT
DENDRITIC SN GROWTH. THERE WL BE 2 INCHES ACCUM AT MOST THE REST OF
TDAY OVER THE NNW WIND SN BELTS ACRS THE W AND IN WRN ALGER COUNTY
WHERE H925 CNVGC IS SHARPEST.
&&
.DISCUSSION...
...COLD WITH LAKE EFFECT SNOW SHOWERS THROUGH AT LEAST TUESDAY
MORNING...THEN AGAIN LATE WEDNESDAY AFTERNOON THROUGH THE FRIDAY...
AT 500MB...A TROUGH WILL REMAIN OVER THE GREAT LAKES REGION THROUGH
12Z TUESDAY. AT THAT TIME...EXPECT SIGNIFICANT RIDGING OVER THE
WESTERN HALF OF THE NATION...WITH A LARGE TROUGH EAST. LITTLE WILL
CHANGE IN THIS OVERALL PATTERN UNTIL FRIDAY. THE LARGE WESTERN
RIDGE SHOULD INTENSIFY AND SLIDE TO THE CENTRAL PLAINS. THIS WILL
CAUSE THE EASTERN RIDGE TO MOVE TO THE NEW ENGLAND STATES THROUGH
THE FIRST HALF OF NEXT WEEKEND.
WITH THE SIZABLE TROUGH OVERHEAD...SEVERAL SMALLER WAVES CROSSING
THE CWA...AND PLENTY OF COLD AIR...EXPECT LAKE EFFECT SNOW TO REMAIN
A POSSIBILITY THROUGH MUCH OF THE FORECAST PERIOD. NORTH TO
NORTHWESTERLY SFC TO 500MB WINDS WILL BE THE RULE THROUGH 12Z
TUESDAY...ALONG WITH 850MB TEMPERATURES AT OR COOLER THAN -10C. THE
ONLY EXCEPTION TO THIS WILL BE INITIALLY TODAY...AS 850MB WINDS COOL
FROM AROUND -6 TO -8C.
TO BEGIN WITH...THE LONGWAVE TROUGH DIVIDES THE CWA THIS
MORNING...STRETCHING FROM HUDSON BAY THROUGH LAKE SUPERIOR AND DOWN
THROUGH THE MISSISSIPPI DELTA REGION. EXPECT TEMPERATURES TO BE
STEADY TO FALLING WEST...AND RISE A COUPLE OF DEGREES EAST TODAY AS
THE COLDER AIR SLOWLY INVADES EASTERN UPPER MICHIGAN.
MODEL WISE...WILL TRY A BEND OF THE GFS AND ECMWF OUTPUTS...WHICH
WERE DEPICTING A SIMILAR OUTCOME FOR THE NEXT SEVERAL DAYS. THE
13/00Z NAM IS DEEPER AND SLOWER THAN OTHER MODEL GUIDANCE WITH THE
SHORTWAVE TROUGH MOVING OVER WESTERN UPPER MICHIGAN SUNDAY AFTERNOON
AND EVENING. STILL...THE MAIN TROUGH SHOULD BE EAST AND RESIDE OVER
THE LOWER GREAT LAKES BY MONDAY EVENING. OTHER MODEL PERFORMANCES
OF NOTE INCLUDE THE 14/12Z UKMET AND THE 15/00Z CANADIAN WHICH WERE
STRONGER THAN MODEL CONSENSUS.
AT THE SURFACE...ONE MAIN QUESTION HAS TO DO WITH THE PROGRESSION OF
THE LOW CURRENTLY OVER NORTHERN BRITISH COLUMBIA. THIS FEATURE IS
EXPECTED TO DIVE SOUTHEASTWARD TO CENTRAL SASKATCHEWAN BY 00Z
SUNDAY. THE NAM AND 14/12Z CANADIAN KEEP THE SURFACE LOW IN
TACT...MOVING IT TO CENTRAL MINNESOTA AND FAR WESTERN LAKE SUPERIOR
BY 18Z SUNDAY. HOWEVER...THE CONSENSUS IS TO HAVE THIS LOW PHASE
INTO THE MUCH STRONGER LOW OVER QUEBEC. DUE TO THE MODEL DIFFERENCES
AND THEIR LOWER PRECIPITATION/MOISTURE OUTPUT...THERE HAS BEEN
LITTLE DEVIATION FROM THE PREVIOUS FORECAST ISSUANCE FOR THIS
PERIOD. ALSO... ONLY VERY MINOR TWEAKS WERE MADE BEYOND DAY
3/TUESDAY.
&&
.AVIATION (FOR THE 18Z TAF ISSUANCE)...
AT CMX...EXPECT MVFR CIGS TO PREDOMINATE THIS FCST PD WITH CHILLY NW
FLOW UNDER LOWERING SUBSIDENCE INVRN. ALTHOUGH THERE MAY BE SOME
-SHSN FROM TIME TO TIME...THERE DOES NOT APPEAR TO A PD WHERE
PERSISTENT HEAVIER SHSN WL REDUCE VSBY BLO VFR RANGE IN GENERALLY
UNFVRBL NNW FLOW. OTRW...SOME DRYING NOW SHOWING UP OVER NW LK SUP
MAY RAISE CIGS TO VFR RANGE FOR A TIME LATE THIS AFTN/EARLY EVNG.
AT KSAW...THERE LOOKS TO BE A PD THIS AFTN BEFORE DEEPER MSTR
DEPARTS WHERE OCNL HEAVIER SHSN MAY REDUCE VSBY/CIGS TO IFR RANGE
WITH ENHANCED LLVL CNVGC. ONCE THE MSTR DEPARTS THIS EVNG AND LLVL
FLOW BACKS MORE NW...DOWNSLOPE WIND COMPONENT WL RESULT IN VFR
CONDITIONS FOR MUCH OF THE NGT. SOME MORE MVFR CIGS ARE PSBL ON SUN
WITH ARRIVAL OF ANOTHER UPR DISTURBANCE.
&&
.MARINE (FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)...
NW WINDS UP TO 30 KNOTS ON LK SUPERIOR WILL CONTINUE THROUGH
TONIGHT. WINDS PICK UP AGAIN ON SUNDAY NIGHT WITH A STRONG COLD
FRONT THAT PUSH THROUGH THE AREA. NORTH WINDS IN THE WAKE OF THE
COLD FRONT WILL AGAIN BE UP TO 30 KNOTS. GALES ARE POSSIBLE LATE WED
INTO THU BEHIND ANOTHER COLD FRONT AS COLDER AIR MOVES INTO THE
REGION. THIS LOOKS TO BE THE STRONGEST WINDS FOR THIS PERIOD.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...NONE.
&&
$$
UPDATE...KC
DISCUSSION...KF
AVIATION...KC
MARINE...GM
AREA FORECAST DISCUSSION...UPDATED
NWS MARQUETTE MI
1240 AM EST SAT NOV 15 2008
UPDATED AVIATION DISCUSSION FOR 06Z TAF ISSUANCE
.SYNOPSIS... ISSUED AT 325 PM EST
12Z RAOBS/LATEST WV IMAGERY AND RUC ANALYSIS SHOW UPR TROFFING OVER
CNTRL NAMERICA BTWN RDG ALG THE W COAST AND IN THE WRN ATLANTIC.
SHRTWV EMBEDDED WITHIN THE UPR TROF IS OVER NRN LWR MI AND HEADING
NEWD...TAKING DEEP MSTR/WDSPRD RA WITH IT. 12Z GRB RAOB/11Z TAMDAR
SDNG FM SAW SHOW MID LVLS HAVE DRIED APPRECIABLY WITH DNVA IN THE
WAKE OF THIS SYS OVER UPR MI...BUT SOME ISOLD -SHRA/PTCHY -DZ
PERSIST OVER THE NRN TIER IN THE WNW FLOW WITHIN THE MOIST LYR BLO
THE INVRN BASE BTWN H85-825. ANOTHER SHRWTV/ACCOMPANYING SFC-H85
COLD FNT WITH DEEPER MSTR THRU H5 IS SWINGING SWD INTO THE NRN
PLAINS/MN. ONLY SOME LGT -SHSN ARE FALLING ALG THE COLD FNT AS
NUMERICAL MODELS SUG CAD IS OVERPOWERING ANY DPVA TO RESULT IN
LARGER SCALE QVECTOR DVGC. BUT QUITE A BIT OF LO CLD IS EVIDENT WELL
N OF THE FNT INTO SCNTRL CAN...WHERE 12Z YQD RAOB SHOWS CONSIDERABLE
LLVL MSTR AND H85 TEMP AT -11C. CYWG REPORTED SOME -FZDZ AT 15Z. THE
STRONGEST N-NW WINDS BEHIND THE FNT ARE RESTRICTED TO THE NRN
PLAINS...WHERE THE H85 WINDS AT BIS/GGW ARE IN THE 40-45KT RANGE AND
A SHARP PRES RISE CENTER (UP TO 8MB/3HRS) IS DRIFTING N-S. FARTHER
UPSTREAM...A POTENT SHRTWV IS NOW TOPPING THE RDG OFF THE W COAST
AND GETTING READY TO SLAM INTO BRITISH COLUMBIA.
&&
.SHORT TERM DISCUSSION (TNGT/SAT)... ISSUED AT 325 PM EST
MAIN FCST CONCERNS IN THE SHORT TERM REVOLVE ARND LK EFFECT SN CHCS/
AMTS.
FOR TNGT...SHRTWV/SFC COLD FNT NOW IN NRN MN ARE PROGGED TO SWING
THRU THE UPR GRT LKS. LLVL FLOW IS PROGGED TO GRDLY VEER MORE NNW BY
12Z SAT AND DRAG COLDER AIR NOW TO THE NW OVER LK SUP...WITH 12Z H85
TEMPS FCST FM ABOUT -8C AT WHITEFISH PT TO -11C OVER WRN LK SUP.
ALTHOUGH SOMEWHAT DEEPER MSTR TO THE NW IS PROGGED TO GRDLY
INFILTRATE THE UPR LKS...MODELS CONTINUE TO ADVERTISE LARGER SCALE
QVECTOR DVGC WITH SUBSIDENCE IN THE MOIST LYR/DENTRITIC SN GROWTH
LYR. INVRN HGT FCST TO REMAIN NEAR 5K FT UNDER THIS SUBSIDENCE. BEST
CHC FOR MORE SGNFT LES WL BE OVER THE W FM GOGEBIC TO SRN CMX
COUNTIES AFT 06Z...WHERE NAM/GFS/LOCAL HIER RES MODELS HINT AT
SHARPER H925 CNVGC WITH INCRSG LK-H85 TEMP DIFFERENCE ARPCHG 17C.
LES CHART SUGS NO MORE THAN 2-4"/12HR PD UNDER ANTICIPATED
CONDITIONS...SO WL ISSUE NO ADVYS ATTM. OVER THE E...PCPN WL BE AT
LEAST A MIX WITH RA FOR MUCH OF THE NGT...WITH SLOW TRANSITION TO
MORE SN LATE. MIN TEMPS NOT FAR BLO 32 WL LIMIT ANY ACCUM IN THESE
AREAS. SINCE SOME -FZDZ WAS OBSVD AT A FEW SPOTS UPSTREAM EARLIER...
THIS PCPN TYPE MAY BE PSBL IN THE UPSLOPE AREAS WITH BULK OF MSTR IN
THE LYR WARMER THAN -10C UNTIL LATE. AWAY FM LK SUP...EXPECT LTL IF
ANY PCPN. SINCE SHARPER PRES GRADIENT/PRES RISE MAXIMUM TO THE W IS
FCST TO REMAIN TO THE W...EXPECT REALLY STRONG NNW WINDS TO STAY W
OF THE THE FA.
ON SAT...CHILLY NNW FLOW IS FCST TO CONTINUE WITH LES MOST NMRS IN
AREAS IMPACTED BY 330-340 FLOW. IN ABSENCE OF DYNAMIC FORCING/NARROW
INTERSECTION OF MOIST LYR/DENDRITIC SN GROWTH ZN WITH SUBSIDENCE
FCST IN THE DGZ...EXPECT SN AMTS TO BE LIMITED. BEST CHC FOR ACCUMS
WL BE IN THE MRNG BEFORE CONTINUED SUBSIDENCE IN THE AFTN REALLY
DRIES OUT THE MID LVLS AND SHARPENS INVRN BASE ARND 5K FT. EXPECT
LTL DIURNAL RECOVERY IN TEMP WITH CONSIDERABLE CLD COVER UNDER INVRN
AND STEADY/SLOWLY FALLING FCST H85 TEMPS.
COORDINATED WITH GRB.
.LONG TERM (SAT NIGHT THROUGH NEXT FRI)...
LAKE EFFECT THROUGH THE PERIOD. SOME POTENTIAL FOR SIGNIFICANT SNOW
ACCUMULATIONS.
EXPECTED LONGWAVE PATTERN IS WELL AGREED UPON BY MAJORITY OF MEDIUM
RANGE MODELS. MAIN FEATURE IS AMPLIFYING TROUGH FM EASTERN CANADA
INTO THE GREAT LAKES AND THE NORTHEAST CONUS. THIS TROUGH LOOKS TO
PERSIST RIGHT INTO NEXT WEEKEND. RESULT FOR UPPER MICHIGAN IS BLO
NORMAL TEMPS WITH OCCASIONAL BOUTS OF MODERATE TO HEAVY LK EFFECT
SNOW. BEST CHANCE OF A MORE WIDESPREAD...SYSTEM...SNOW IS ON SUNDAY
OUT AHEAD OF A STRONG COLD FRONT...THEN AGAIN ON WEDNESDAY AS A
CLIPPER LOW PRESSURE DROPS ACROSS UPR GREAT LAKES.
SATURDAY NIGHT THROUGH SUNDAY...SNOW SHOWERS CONTINUE SATURDAY NIGHT
BUT DIMINISH DUE TO LOWERING INVERSION AND DRYING BENEATH INVERSION.
INCREASING ANTICYCLONIC FLOW IN LOW LEVELS WILL NOT HELP MATTERS
EITHER. LOCALLY RUN WRF-ARW SHOWS H95 CONVERGENCE LOCALLY MAXIMIZED
OVR WRN HIGHER TERRAIN BTWN ONTONAGON AND HOUGHTON AND ALSO IN
SNOWBELTS EAST OF MARQUETTE IN ALGER AND NORTHERN SCHOOLCRAFT. TOP
OF INVERSION ONLY AROUND -10C SO DOES NOT LOOK TOO GOOD FM
SNOWGROWTH STANDPOINT. UP TO A FEW INCHES OF SNOW EXPECTED SATURDAY
NIGHT. SHORTWAVE CURRENTLY OVR NORTHERN BRITISH COLUMBIA APPROACHES
SUNDAY. WARM AIR ADVECTION H925-H85 AND ISENTROPIC LIFT AHEAD OF THE
WAVE RESULTS IN SWATH OF LGT SNOW ACROSS WRN HALF OF CWA BY 00Z MON.
GOOD AGREEMENT FM CANADIAN...GFS...AND LOCAL WRF ON THIS
SCENARIO...ECMWF JUST A BIT SLOWER. MOS POPS LOOK TOO LOW GIVEN THE
SIGNALS FM THE MODELS. EXPECT A HIGH POP/LOW QPF SNOWFALL. ADJUSTED
POPS TO HIGH CHANCE.
SUNDAY NIGHT THROUGH MONDAY NIGHT...SFC LOW TIED TO THE SHORTWAVE
SLIDES ACROSS UPR MI EARLY SUNDAY EVENING PROPELLING A STRONG COLD
FRONT THROUGH THE AREA. SUNDAY NIGHT INTO MONDAY COULD BE A
SIGNIFICANT LAKE EFFECT EVENT IN NRLY FLOW AREAS SUCH AS IWD AND
HIGHER TERRAIN OF NCNTRL CWA. H85 TEMPS FALL TO -15C BY LATE SUNDAY
NIGHT WHILE H7 MOISTURE REMAINS IN WAKE OF THE SHORTWAVE TROUGH.
SINCE AIR IS COLD ENOUGH TO SUPPORT LK EFFECT INITIALLY AND SYNOPTIC
SUPPORT ONLY INCREASES...EXPECT WELL ORGANIZED LAKE ENHANCED SNOW
THROUGH THE OVERNIGHT HOURS...THEN BECOMING MORE PURE LES LATE
SUNDAY NIGHT. GFS SOUNDINGS IMPRESSIVE WITH MOISTURE TO H7 SUNDAY
EVENING AND STRONGEST UPWARD MOTION LOCATED WITHIN DEEP DENDRITIC
GROWTH ZONE. TEMP PROFILES PROGRESSIVELY COOL THROUGH THE NIGHT...SO
EXPECT SNOW RATIOS AND RESULTANT ACCUMS TO INCREASE AS WELL. DEEP
MOISTURE PULLS OUT EARLY MONDAY...BUT LK EFFECT MOISTURE/CONVECTION
THAT REMAINS WILL BE CHARACTERIZED BY HIGH SNOW RATIOS...SO EXPECT
THE FLUFFY SNOW TO KEEP PILING UP. RAMPED UP POPS ALONG LK SUPERIOR
AND HIT THE HIGHEST POPS WHERE LOW LEVEL CONVERGENCE PERSISTS.
DIMINISHING MOISTURE BLO A LOWERING INVERSION MONDAY NIGHT SIGNALS
THE END OF THE LK EFFECT EVENT.
TUESDAY INTO WEDNESDAY...LINGERING LK EFFECT SNOW CONTINUES TO
DIMINISH THROUGH THE DAY ON TUESDAY. KEPT LIKELY POPS FOR NW FLOW
AREAS IN THE EAST WHERE H85 THERMAL TROUGH IS SLOWEST TO EXIT. LK
EFFECT GRADUALLY SHUTS DOWN THROUGH THE DAY ON TUESDAY OVR NCNTRL
AND OVR WEST CWA AS LOW LEVEL WINDS BACK MORE WRLY AND DRIER AIR
ARRIVES. TUESDAY ALSO APPEARS TO OFFER BEST CHANCE FOR SOME SUNSHINE
THIS WEEK...AND THAT WOULD MAINLY BE OVER SOUTH CENTRAL SECTIONS OF
CWA. SHORTWAVE SLIDING OVR THE RIDGE IN WRN CONUS AND SW CANADA
PUSHES INTO NW ONTARIO LATE TUESDAY NIGHT. WARM AIR ADVECTION WITH
THIS CLIPPER LOW PRESSURE SYSTEM ALLOWS FOR SOME STEADIER...NON LAKE
EFFECT...SNOW TO BREAK OUT INTO NORTHERN UPR MI TUESDAY NIGHT WITH A
BETTER CHANCE ON WEDNESDAY. WINDS BACKING TO THE SW TUESDAY NIGHT
INTO WEDNESDAY MORNING AND H85 TEMPS REMAINING COLD ENOUGH FOR LK
EFFECT MAY LEAD TO POTENTIAL LK EFFECT DOWNWIND OF LK MICHIGAN.
CLIMATOLOGICALLY ...S/SW FLOW LK MICHIGAN EVENTS ARE RARE FOR OUR
CWA...BUT DEFINETELY WORTH CHANCE POPS.
DAYS 6-7...MORE COLD AIR ON NRLY WINDS POURS IN BY THURSDAY AND
LK EFFECT BEGINS AGAIN. CYCLONIC FLOW...85 TEMPS LOWERING BLO
-15C...AND ADEQUATE H85-H7 MOISTURE INTO FRIDAY POINTS TO LIKELY
SNOW SHOWERS NEAR LAKE SUPERIOR WITH THE POTENTIAL FOR ADDITIONAL
SIGNIFICANT ACCUMULATIONS.
&&
.AVIATION (FOR THE 06Z TAF ISSUANCE)...
UNDER DEVELOPING LAKE EFFECT REGIME...EXPECT MVFR CIGS TO BE THE
RULE AT KCMX THRU THIS FCST PERIOD. ALTHOUGH FREQUENT -SHSN ARE
EXPECTED AT KCMX...IT`S NOT A SETUP FOR PERSISTENT HEAVIER SHSN...SO
IT`S DIFFICULT TO FCST ANY PERIODS THAT WILL HAVE PREVAILING VIS BLO
VFR IN -SHSN. WHILE THERE MAY BE SOME SHORT PERIODS OF MVFR VIS AND
PERHAPS BRIEF IFR VIS...THIS FCST WILL SIMPLY REFLECT A PREVAILING
VFR VIS IN -SHSN AT KCMX.
AT KSAW...VFR CIGS WILL TREND TO MVFR LATE IN THE NIGHT WITH MVFR
CIGS THEN LIKELY PREVAILING THRU THE END OF THIS FCST PERIOD. AS
WINDS VEER TO A MORE FAVORABLE NNW DIRECTION IN THE MORNING...
ALLOWING SOMEWHAT HEAVIER BANDS OF -SHSN OFF THE LAKE TO REACH
KSAW...EXPECT VIS TO DROP TO A PREVAILING MVFR VIS. IMPROVEMENT
BACK TO VFR VIS EXPECTED EARLY IN THE AFTN.
&&
.MARINE (FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE)...
COLD FRONT PASSING THIS EVENING SETS UP NW WINDS UP TO 30 KNOTS ON
LK SUPERIOR THROUGH THIS WEEKEND. WINDS MAY DIMINISH BELOW 25 KNOTS
ON SUNDAY AHEAD OF A SFC LOW AND STRONG COLD FRONT THAT PUSH THROUGH
THE AREA SUNDAY NIGHT. NORTH WINDS IN THE WAKE OF THE COLD FRONT
COULD PRODUCE GALE FORCE GUSTS SUNDAY NIGHT AND MONDAY. DID NOT
INCLUDE GALES IN THIS FCST THOUGH SINCE MAXIMUM PRESSURE RISE/FALL
COUPLET PASSES WEST OF LK SUPERIOR. WINDS LESS THAN 30 KNOTS FOR
TUESDAY AS WEAK RIDGE CROSSES THE REGION. SOUTHERLY WINDS POP UP TO
30 KNOTS ON WEDNESDAY AS STRONGER LOW PRESSURE SYSTEM DIVES ACROSS
THE UPPER GREAT LAKES.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...NONE.
LAKE SUPERIOR...NONE.
LAKE MICHIGAN...NONE.
&&
$$
SYNOPSIS...KC
SHORT TERM...KC
LONG TERM...JLA
AVIATION...ROLFSON
MARINE...JLA
AREA FORECAST DISCUSSION
NWS RALEIGH NC
110 PM EST SUN NOV 16 2008
.SYNOPSIS...
CIRCULATION AROUND A STRONG LOW PRESSURE SYSTEM OVER SOUTHEAST
CANADA AND HIGH PRESSURE OVER THE SOUTH CENTRAL U.S. WILL FUNNEL
MUCH COOLER AIR INTO CENTRAL NORTH CAROLINA TODAY THROUGH MONDAY.
TEMPERATURES ARE EXPECTED TO BE BELOW NORMAL THROUGH MUCH OF THE
WEEK.
&&
.NEAR TERM /THROUGH TONIGHT/...
AS OF 1030 AM SUNDAY...
INCREASING SUBSIDENCE AND LOWERING OF THE INVERSION IS EVIDENT
COMPARING THE 12Z GSO SOUNDING TO LATER AMDAR SOUNDING AT 13Z.
BELOW THE INVERSION...QUITE DRY WITH PWATS IN THE 0.3 INCH
RANGE...EXPECT MAINLY FEW TO SCATTERED STRATOCUMULUS OUTSIDE OF THE
NORTHERN TIER OF THE CWFA WHICH MAY SEE INTERVALS WHERE CLOUDS
PREDOMINATE. WIND SPEEDS ABOVE THE INVERSION ARE IN THE 30KT
RANGE...AND EXPECT SOME MIXING DOWN OF THESE WINDS DUE TO DRY
ADIABATIC LOW LEVEL PROFILE...WILL INCREASE GUST SPEEDS A BIT THIS
AFTERNOON...25 KTS ACROSS THE NORTH. TEMPS WILL BE INCREASING SLOWLY
AS STRUGGLE BETWEEN INSOLATION AND DOWNSLOPE WARMING ARE OFFSET BY
THE STRONG COLD AIR ADVECTION...THICKNESS TRENDS SUPPORT ONGOING
FORECAST IN THE LOW AND MID 50S. AS SUCH...NO ADJUSTMENTS NEEDED
EXCEPT MINOR TWEAKING ON THE HOURLY TRENDS.
TONIGHT...POTENTIAL FOR SOME OROGRAPHIC INDUCED CLOUDS TO DEVELOP
AFTER 06Z. AS POCKET OF MID LEVEL MOISTURE WILL BE CARRIED BY
50-60KT WINDS AT 10000FT. ORIENTATION OF FLOW INTO THE APPALACHIANS
(ALMOST PERFECTLY PERPENDICULAR) AND PRESENCE OF STABLE LAYER
ALOFT SUPPORT DEVELOPMENT OF MID/HIGH LEVEL CLOUDS LATE TONIGHT
INTO MONDAY MORNING. IF CLOUDS DEVELOP...THIS MAY HAVE SOME AFFECT
ON MIN TEMPS. HOWEVER...DEFINITE POSSIBILITY FOR CLOUDS NOT TO
DEVELOP UNTIL DAYBREAK MON OR LATER. THUS WILL LEAN TEMPS TOWARD
THE COOL END OF MOS GUIDANCE (LOWER 30S).
&&
.SHORT TERM /MONDAY THROUGH WEDNESDAY/...
AS OF 325 AM SUNDAY...
L/W TROUGH WILL REMAIN OVER THE EASTERN U.S. THROUGH MID WEEK WITH
AMPLIFICATION OF TROUGH EXPECTED TUESDAY AS POTENT VORT MAX DIVES SE
FROM THE GREAT LAKES INTO THE MID ATLANTIC. THIS VORT MAX WILL DRAG
A DRY COLD FRONT ACROSS THE REGION LATE MONDAY. AHEAD OF FRONT...LEE
SIDE TROUGH WILL INDUCE LOW LEVEL SW FLOW. THIS WILL AID TO BOOST
AFTERNOON TEMPS INTO HE 55-60 DEGREE RANGE OVER THE REGION.
FRONTAL PASSAGE TO OCCUR LATE MONDAY INTO MONDAY EVENING. STRONG
COLD AIR ADVECTION WILL KEEP WINDS UP OVERNIGHT. SIMILAR TO CURRENT
NIGHT...WILL LIKELY SEE GUSTS 18-22KTS.
STRONG COLD AIR ADVECTION WILL CONTINUE TUESDAY. 850MB THERMAL
TROUGH WILL SET UP JUST TO OUR NW WITH 850MB TEMPS PROGGED TO BE
BETWEEN MINUS 7 AND MINUS 10 DEGREES C. THICKNESSES WITH FULL SUN
SUGGEST MAX TEMPS NO HIGHER THAN UPPER 30S TO LOWER 40S. SINCE LOW
LEVEL FLOW WILL HAVE A DOWNSLOPE COMPONENT...MAY SEE SOME ADIABATIC
WARMING. STILL MAX TEMPS IN THE MID TO UPPER 40S WILL BE AT LEAST 15
DEGREES BELOW NORMAL. IN SPITE OF FULL SUN AND NW LOW LEVEL FLOW
(DOWNSLOPE COMPONENT)...MAX TEMPS TUESDAY PROGGED TO BE ABOUT 15
DEGREES BELOW NORMAL. IT WILL BE BRISK WITH GUSTS 20-25 MPH
EXPECTED.
TUESDAY NIGHT...SURFACE RIDGE AXIS BUILDS INTO REGION. THIS SHOULD
CAUSE SURFACE WINDS TO DECOUPLE DURING THE EVENING HOURS. MODEL
THICKNESSES STILL PROGGED TO BE IN THE LOW/MID 1270S BY WED MORNING.
THUS...WIDESPREAD MID 20S PROBABLE WITH THE NORMALLY COLDER LOCALES
DIPPING TO NEAR 20.
SOME MODIFICATION OF AIR MASS WED AS LOW LEVEL FLOW BECOMES MORE
WESTERLY. PROJECTED MAX TEMPS IN THE UPPER 40S TO LOWER 50S LOOK ON
TARGET.
&&
.LONG TERM /WEDNESDAY NIGHT THROUGH SATURDAY/...
AS OF 340 AM SUNDAY...
LITTLE CHANGE IN SENSIBLE WEATHER THIS PERIOD AS L/W TROUGH
MAINTAINS POSITION OVER THE EASTERN U.S. ANOTHER VORT MAX WILL
AMPLIFY THE TROUGH LATE IN THE WORK WEEK...LEADING TO ANOTHER COOL
DOWN BY FRIDAY. MEDIUM RANGE GUIDANCE IN GOOD AGREEMENT WITH IDEA
OF MOVING L/W TROUGH E-NE SATURDAY INTO SUNDAY. S/W RIDGE IN WAKE OF
EXITING SYSTEM WILL MODIFY AIR MASS DURING THE WEEKEND. THIS SUGGEST
TEMPS RETURNING TO NEAR NORMAL VALUES BY SUNDAY.
&&
.AVIATION /18Z SUNDAY THROUGH FRIDAY/...
AS OF 100 PM SUNDAY...
ONLY SCATTERED STRATOCUMULUS DEVELOPING IN THE NORTHWEST BENEATH THE
SUBSIDENCE INVERSION THIS AFTERNOON. THESE WILL EVAPORATE WITH LOSS
OF INSOLATION THIS EVENING. WESTERLY WINDS GUSTING TO 20 KNOTS WILL
RELAX AS WELL...BECOMING LIGHT AND PERHAPS CALM IN THE WEE HOURS.
THE BROAD TROF OVER THE EASTERN CONUS WILL DEEPEN SOMEWHAT OVERNIGHT
AND SHIFT A STRONG SHEAR AXIS SOUTH ACROSS THE AREA BY MORNING.
EXPECT TO SEE SOME INCREASING HIGH CLOUDINESS ACCOMPANY THIS
AXIS...AND THE STRONG...NEAR UNI-DIRECTIONAL FLOW ORTHOGONAL TO THE
MOUNTAINS COULD OROGRAPHICALLY ENHANCE THE CLOUDINESS...PRODUCING
MORE WIDESPREAD AND THICKER CLOUDS ACROSS THE NORTHERN TIER...ALBEIT
STILL ABOVE 10KFT.
WINDS TOMORROW WILL PICK UP AFTER SUNRISE AND BACK MORE TOWARDS THE
SOUTHWEST AS THE DEEPER WESTERLY FLOW ALOFT AND DOWNSLOPE WARMING
INDUCES A LEE SURFACE TROF. SPEEDS OF 10 TO 12 KNOTS ARE EXPECTED BY
MID MORNING WITH POSSIBLE GUSTS TO NEAR 20 KNOTS IN THE AFTERNOON.
THE SURFACE TROF WILL BE PUSHED OFFSHORE EARLY TOMORROW NIGHT BY A
REINFORCING PUNCH OF COLD AIR WITH WINDS BECOMING NORTHWEST AROUND
00Z.
VFR CONDITIONS ARE EXPECTED THROUGH THE REMAINDER OF THE WEEK AS
NORTHWESTERLY FLOW DOMINATES. UPPER LEVEL DISTURBANCES IN THE NW
FLOW WILL LIKELY PRODUCE SOME MID/HIGH CLOUDS BUT FAIR WEATHER IS
EXPECTED DURING THE PERIOD.
&&
.RAH WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...WSS
NEAR TERM...MLM
SHORT TERM...WSS
LONG TERM...WSS
AVIATION...MLM
AREA FORECAST DISCUSSION
NWS RALEIGH NC
440 AM EST SAT NOV 15 2008
.SYNOPSIS...
A STRONG COLD FRONT WILL APPROACH FROM THE EAST AND CROSS THE AREA
ON LATE THIS AFTERNOON. COLDER AIR WILL FLOW INTO THE AREA BEHIND
THE FRONT TONIGHT AND SUNDAY.
&&
.NEAR TERM /THROUGH TONIGHT/...
AS OF 430 AM SATURDAY...
CONVECTION ASSOCIATED WITH SHEARING UPPER LEVEL DISTURBANCE WILL
PERSIST THROUGH 12Z IN NARROW ZONE OF STRONG LOW LEVEL CONFLUENCE
OVER THE COASTAL PLAIN. MAY SEE AN ADDITIONAL STRONG/SEVERE STORMS
ALONG THE EASTERN PERIPHERY OF CWA THROUGH 12Z.
AMPLIFYING UPPER LEVEL TROUGH WILL SHARPEN COLD FRONT AS IT
APPROACHES/CROSSES CENTRAL NC LATER TODAY. AIR MASS AHEAD OF FRONT
WILL BE MODERATELY UNSTABLE WITH SURFACE BASED CAPE VALUES BETWEEN
1200-1800 J/KG....AND LOW LEVEL HELICITY BETWEEN 150-250 M2/SEC2.
EXPECT ANOTHER ROUND OF STORMS TO AFFECT THE WESTERN AND SOUTHERN
PIEDMONT BETWEEN 14Z-18Z...AND THE REMAINDER OF CENTRAL NC BETWEEN
16-21Z. DUE TO STRONG KINEMATICS WITH A LOW LEVEL JET 45-55KTS OVER
THE COASTAL PLAIN THIS AFTERNOON...EXPECT A LINE OF STRONG/SEVERE
CONVECTION TO OCCUR AHEAD OF THE FRONT WITH POTENTIAL FOR ISOLATED
SUPERCELLS IN THE COASTAL PLAIN. TEMPS TODAY...AS THE PAST FEW DAYS
HARD TO PINPOINT. NOT EXPECTING ANY BREAKS IN THE OVERCAST SKIES BUT
IF BREAKS WERE TO OCCUR THIS MORNING...MAX TEMPS MAY END UP BEING
2-3 DEGREES WARMER.
COLD FRONT WILL EXIT LATE TODAY/EARLY TONIGHT WITH PASSAGE OF
850-700MB TROUGHS OCCURRING BETWEEN 00-06Z. SKIES WILL SLOWLY CLEAR
WEST-TO-EAST AFTER 00Z WITH SHOWERS ENDING/DIMINISHING BY 04Z.
&&
.SHORT TERM /SUNDAY THROUGH MONDAY/...
AS OF 445 AM SATURDAY...
MUCH COLDER AIR WILL OVERSPREAD REGION SUNDAY INTO SUNDAY NIGHT. DUE
TO LOW LEVEL COLD AIR ADVECTION AND BUILDING SURFACE HIGH INTO
REGION...EXPECT BRISK WINDS. THICKNESSES WITH FULL TO PARTIAL SUN
SUPPORT MAX TEMPS IN THE LOW/MID 50S. CHILLY NIGHT SUNDAY NIGHT WITH
RIDGE AXIS OVER THE AREA. MIN TEMPS 30-35.
AIRMASS MODIFIES MONDAY PLUS LEE SIDE TROUGH WILL PROMOTE SW SURFACE
FLOW. THIS SHOULD RESULT IN MAX TEMPS IN THE MID/UPPER 50S.
&&
.LONG TERM /MONDAY NIGHT THROUGH FRIDAY/...
AS OF 245 PM FRIDAY...
AT KGSO...KRDU...AND KFAY...ONE HAS TO GO BACK TO MARCH 30 FOR THE
LAST DAY WHEN HIGHS DID NOT GET OUT OF THE 40S...AND TUESDAY IS A
DAY THERE STANDS A GOOD CHANCE OF THIS OCCURRING IN CENTRAL
NORTH CAROLINA AS THICKNESSES FALL COINCIDENT WITH A LONG-WAVE
TROUGH MOVING ACROSS THE STATE AND THE PRESENCE OF NORTHERLY
SURFACE FLOW. BOTH THE GFS AND THE ECMWF ARE CLOSE IN THE TIMING
OF THE TROUGH AND AT LEAST MODERATE...MAINLY CHANNELED VORTICITY
MOVING ACROSS THE STATE FROM LATE MONDAY NIGHT THROUGH TUESDAY. IN
GENERAL...THE GUIDANCE KEEPS THE FOCUS OF MID-LEVEL MOISTURE TO
THE NORTH OF CENTRAL NORTH CAROLINA...BUT JUST TO THE NORTH.
THICKNESSES ARE OBVIOUSLY COLD...AND THOUGH THE OVERALL AIR MASS
WILL BE DRY AND ANY PRECIPITATION LIKELY WOULD HAVE A VERY HARD
TIME MEASURING...WILL HAVE TO OBSERVE GUIDANCE TRENDS OVER THE
NEXT COUPLE OF DAYS OR SO TO ASSESS THE DEGREE OF MOISTURE ALOFT
AND THE STRENGTH OF MID-LEVEL SUPPORT. CURRENTLY...BOTH THE GFS
AND THE ECMWF ARE FOCUSING ON AVAILABLE MOISTURE PRIMARILY IN A
NARROW LAYER AROUND 700MB.
HEIGHTS BEGIN TO RISE QUICKLY LATE TUESDAY INTO WEDNESDAY. HOWEVER...
LIGHT WINDS EXPECTED AT THE SURFACE WITH FEW CLOUDS ANTICIPATED AT
THIS TIME SHOULD ALLOW OVERNIGHT LOWS TO FALL WELL INTO THE 20S ON
AVERAGE ACROSS CENTRAL NORTH CAROLINA TUESDAY NIGHT INTO WEDNESDAY
MORNING. TIMING OF SURFACE AND UPPER-LEVEL FEATURES THEN BEGINS TO
DIVERGE SOME LATE NEXT WEEK WITH THE 06Z GFS FASTER WITH THE
APPROACH AND PASSAGE OF A SURFACE COLD FRONT AND UPPER TROUGH
FRIDAY...WHILE THE ECMWF IS LATER...LATE FRIDAY INTO EARLY SATURDAY.
THE 12Z GFS HAS TRENDED SLOWER...MORE TOWARD THE ECMWF...THOUGH ONCE
AGAIN MOISTURE IS LIMITED THROUGHOUT THE OVERALL AIR MASS. WILL
CONTINUE TO KEEP THE FORECAST DRY FOR NOW ESPECIALLY OUT TO THE
SEVENTH DAY...THOUGH THICKNESSES ARE WARM. HIGHS SHOULD BE IN THE
50S FOR THURSDAY AND FRIDAY. BEYOND THIS PERIOD...THE LATEST GFS
HAS TRENDED TO A LESS AMPLIFIED SOLUTION WITH THE UPPER TROUGH IN
THE EASTERN CONUS WITH CORRESPONDINGLY HIGHER THICKNESSES AND
HEIGHTS. WHILE STILL ANTICIPATED TO BE BELOW NORMAL...TEMPERATURES
INTO NEXT WEEKEND MAY NOT BE QUITE AS COOL AS THOSE EXPECTED EARLY
IN THIS PART OF THE FORECAST.
&&
.AVIATION /06Z SATURDAY THROUGH WEDNESDAY/...
AS OF 125 AM SATURDAY...
THE WARM FRONT HAS ADVANCED NORTHWESTWARD INTO THE TRIAD AS OF 06Z
WITH AN ESE WIND NOW REPORTED AT KGSO AND KINT. FAIRLY LARGE AREA OF
CONVECTION ORIENTED S TO N PRESENTLY MOVING NE ACROSS MUCH OF
FORECAST AREA. THIS AREA OF CONVECTION IS IN RESPONSE TO LARGE SCALE
FORCING ACROSS THE SOUTHEAST FROM AN APPROACHING SHORT WAVE ACROSS
SOUTHERN AL/GA. NUMEROUS SHOWERS EMBEDDED THUNDERSTORMS WILL SWEEP
EAST ACROSS CENTRAL AND EASTERN TAF LOCATIONS THROUGH AROUND 10Z.
CIGS AND VSBY WILL VARY OVERNIGHT WITH LIFR/IFR CIGS AND VSBY
ASSOCIATED WITH THE PREVIOUSLY MENTIONED CONVECTION. SCATTERED
SHOWERS AND POSSIBLY A THUNDERSTORM IS POSSIBLE FOR THE REMAINDER OF
THE OVERNIGHT AND EARLY MORNING HOURS BEFORE ANOTHER AREA OF
WIDESPREAD CONVECTION SWEEPS EAST ON SAT MORNING AND EARLY AFTERNOON
ASSOCIATED WITH A COLD FRONT. CIGS AND VSBYS WILL IMPROVE TO MVFR
OUTSIDE OF THE CONVECTION.
0357Z AMDAR SOUNDING AT KRDU AND REPORTED A 29KT WIND AT AROUND 1500
FEET WITH A 0518Z AMDAR SOUNDING AT KGSO JUST BEFORE THE WARM
FRONTAL PASSAGE WITH A FAIRLY LIGHT WIND AT LESS THEN 15KTS UP TO
AROUND 2500 FEET JUMPS TO AROUND 50KTS AT 2500 FEET. WILL CONTINUE
TO EXCLUDE MENTION OF LLWS.
ON SATURDAY ANOTHER BAND OF SHOWERS AND SCATTERED THUNDERSTORMS...
WITH POTENTIALLY GUSTY WINDS IN EXCESS OF 40KT IN THE AFTERNOON.
THIS BAND OF CONVECTION IN THE AFTERNOON WILL BE ASSOCIATED WITH A
COLD FRONTAL PASSAGE. IFR TO MVFR CIGS EXPECTED THROUGHOUT THE
DAY... WITH MVFR VSBYS... REDUCING AT TIMES INTO THE LIFR CATEGORY
WITH HEAVY RAIN SHOWERS.
CIGS WILL RISE ABRUPTLY FROM MVFR TO VFR AFTER THE COLD FRONT PASSES
SATURDAY AFTERNOON ACROSS THE WEST AND IN THE LATE IN THE DAY ACROSS
THE EAST. WINDS WILL SHIFT TO THE WEST AT 15-25KT.
VFR CONDITIONS EXPECTED SUNDAY THROUGH TUESDAY.
&&
.RAH WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...WSS
NEAR TERM...WSS
SHORT TERM...WSS
LONG TERM...DJF
AVIATION...BLAES/BADGETT
AREA FORECAST DISCUSSION
NWS RALEIGH NC
125 AM EST SAT NOV 15 2008
.SYNOPSIS...
A WARM FRONT WILL PUSH NORTHWARD THROUGH THE AREA TONIGHT. A
STRONG COLD FRONT WILL APPROACH FROM THE EAST TONIGHT AND CROSS THE
AREA SATURDAY AFTERNOON. SHOWERS AND THUNDERSTORMS WILL REMAIN
NUMEROUS TO WIDESPREAD ACROSS THE REGION UNTIL THE FRONTAL PASSAGE
ON SATURDAY. MUCH COLDER AIR WILL FILTER INTO CENTRAL NORTH CAROLINA
BEHIND THE FRONT.
&&
.NEAR TERM /THROUGH SATURDAY/...
AS OF 1030 PM FRIDAY...
THE COASTAL FRONT HAS REALLY STRUGGLED TO MOVE INLAND THIS EVENING
WITH THE RESIDUAL WEDGE BEING MUCH MORE STUBBORN THAN THE MODELS
HAVE ADVERTISED (A KNOWN MODEL BIAS). AS OF 10 PM...THE FRONT IS
STILL LOCATED TO THE SOUTH OF THE CWA AND IS ROUGHLY POSITIONED JUST
NORTHWEST OF NEW BERN...JACKSONVILLE...AND WHITEVILLE BASED ON SFC
THETA-E AND SFC LI ANALYSIS. ACROSS CENTRAL NORTH CAROLINA...
TEMPERATURES HAVE BEEN HOLDING IN THE UPPER 50S IN THE TRIAD TO
LOWER 60S ELSEWHERE WITH DEWPOINTS A DEGREE OR TWO LOWER.
AFTER A GENERAL BREAK IN PRECIPITATION OVER THE PAST FEW
HOURS...HEAVIER SHOWERS AND ISOLATED THUNDERSTORMS ARE BEGINNING TO
MOVE BACK IN FROM THE SOUTHWEST ACROSS SOUTH CAROLINA. THIS
CONVECTION IS BEING GENERATED BY A DEAMPLIFYING SHORTWAVE AND
ASSOCIATED 120 KT UPPER LEVEL JET EJECTING NORTHEAST OUT OF THE
NORTHERN GULF OF MEXICO AND A AHEAD OF THE DEEPENING TROUGH OVER THE
CENTRAL STATES. THE THUNDERSTORM ACTIVITY IS ALL ELEVATED AS IT IS
LOCATED ON THE COOL SIDE OF THE BOUNDARY IN A STABLE SFC LAYER...AS
CAN BE SEEN ON THE 00Z GSO AND FFC SOUNDINGS. WEAK ELEVATED
INSTABILITY IS PRESENT AROUND 850 MB AS MID LEVEL LAPSE RATES BEGIN
TO STEEPEN AHEAD OF THE SHORTWAVE.
EXPECT PRECIPITATION TO INCREASE ACROSS THE REGION OVER THE NEXT
SEVERAL HOURS AS THE SHORTWAVE ENERGY CONTINUES TO QUICKLY MOVE
NORTHEAST. FOR THE NEXT SEVERAL HOURS...ANY THUNDERSTORM ACTIVITY
WILL REMAIN ELEVATED OVER THE MAJORITY OF CENTRAL NORTH CAROLINA.
DEEP LAYER SHEAR OF 45-55 KT IS SUPPORTIVE OF ELEVATED SUPERCELLS
BUT NO DAMAGING WIND OR TORNADO THREAT WILL OCCUR IN THE STABLE
LAYER. LARGE HAIL WOULD BE A THREAT...BUT THAT TOO WILL BE LIMITED
BASED ON THE DEEP MOIST ADIABATIC PROFILES.
THE THREAT OF SFC BASED STORMS INCREASE DURING THE EARLY MORNING
HOURS AS THE COASTAL FRONT CONTINUES TO SLOWLY PUSH INLAND IN
RESPONSE TO THE STRENGTHENING SOUTHERLY FLOW ASSOCIATED WITH THE
INCREASING PRESSURE GRADIENT. SFC BASED INSTABILITY OF 500-1000 J/KG
SHOULD SPREAD INLAND...CREATING A ENVIRONMENT MORE FAVORABLE FOR A
FEW STRONG TO SEVERE STORMS...ESPECIALLY IN CLOSE PROXIMITY TO THE
BOUNDARY. DAMAGING WINDS WILL BE THE MAIN THREAT AS THE LOW LEVEL
JET INTENSIFIES TO NEAR 50 KT. A BRIEF TORNADO CANNOT BE TOTALLY
RULED OUT ALONG THE WARM FRONT...BUT THE GENERALLY VEERED NATURE OF
THE SFC FLOW (WINDS MORE S-SW POST FRONT) WILL LIMIT THE OVERALL
POTENTIAL. BEST SEVERE POTENTIAL SHOULD BE IN THE SANDHILLS AND
COASTAL PLAIN THROUGH SUNRISE. TEMPERATURES WHICH HAVE BEEN HOLDING
STEADY WILL GRADUALLY RISE THROUGH DAYBREAK...WITH TEMPS NEAR 70
LIKELY IN THE SOUTHEAST COASTAL PLAIN.
THE WARM SECTOR SPREADS ACROSS MUCH OF THE AREA BY 12Z AS THE STRONG
COLD FRONT BEGINS TO MARCH IN FROM THE WEST. THE FRONT LOOKS TO
CLEAR THE WESTERN PIEDMONT BY LATE MORNING AND THE COASTAL PLAIN BY
LATE AFTERNOON. IMPRESSIVE DYNAMICS ASSOCIATED WITH THE HIGHLY
AMPLIFIED MID AND UPPER LEVEL TROUGH SHOULD SERVE TO FORCE A
CONVECTIVE LINE OF STORMS ALONG THE FRONT. DAMAGING STRAIGHT LINE
WINDS APPEAR TO BE THE BIGGEST THREAT DUE TO THE OVERWHELMING LINEAR
FORCING ALONG THE FRONT. HOWEVER...0-1KM SHEAR IS STILL SUFFICIENT
TO MAINTAIN THE POSSIBILITY OF AN EMBEDDED ISOLATED TORNADO. THE
BEST THREAT APPEARS TO BE OVER CENTRAL AND EASTERN PORTIONS OF THE
AREA WHERE THE GREATEST SFC BASED INSTABILITY SHOULD BE LOCATED DUE
TO THE LATER TIMING OF THE FRONT AND HIGHER CHANCES OF
DESTABILIZATION.
HIGH TEMPS SOMEWHAT TRICKY BASED ON FRONTAL TIMING. HAVE TRIMMED
BACK TEMPS IN THE FAR NW PIEDMONT DUE TO THE LATER EROSION OF THE
WEDGE. HIGHS 63 W TO 74 E. TEMPS/DEWPOINTS BEGIN TO QUICKLY DROP
POST FRONT AS COLD AIR ADVECTION KICKS IN.
&&
.SHORT TERM /SATURDAY NIGHT THROUGH MONDAY/...
AS OF 245 PM FRIDAY...
SATURDAY NIGHT:
A POWERFUL NORTHERN STREAM TROUGH ALOFT -- NOW AMPLIFYING IN
NORTHWESTERLY FLOW ALOFT OVER THE CENTRAL US -- WILL CROSS CENTRAL
NC SATURDAY NIGHT. MODELS CONTINUE TO PROG STRONG Q-VECTOR
CONVERGENCE (OWING TO DCVA AHEAD OF THE TROUGH) AND FGEN IN THE MID
AND UPPER LEVELS. HOWEVER... THE ASSOCIATED ASCENT WILL HAVE NO
MOISTURE TO WORK WITH AS PRECIPITABLE WATERS CRASH TO ONE HALF INCH
OR LESS OVERNIGHT. STRONG LOW LEVEL CAA SENDS LOW LEVEL THICKNESSES
TO A FORECAST MINIMUM IN THE 1305 TO 1315 METER RANGE BY 12Z
SUNDAY... SOME 80 METERS LOWER THAN SATURDAY. THE COLD ADVECTION
SHOULD KEEP A STEADY NW BREEZE (~10 MPH WITH FEW GUSTS UP TO 20
POSSIBLE) UP OVERNIGHT. LOW TEMPERATURES BEHIND THE FRONT OVER THE
NORTHERN PLAINS THIS MORNING WITH SIMILAR THICKNESSES YIELDED LOWS
IN THE MIDDLE TO UPPER 30S. TAKING INTO ACCOUNT SOME AIRMASS
MODIFICATION... LOWS 40 NW TO 47 SE SEEM REASONABLE... AND IS IN
LINE WITH THE SIMILAR 12Z MAV/MET MOS.
SUNDAY AND SUNDAY NIGHT: SURFACE RIDGING WILL EXPAND INTO OUR
REGION FROM THE SOUTHWEST... AS HEIGHTS ALOFT RISE BEHIND THE
DEPARTING UPPER TROUGH. LOW LEVEL THICKNESSES ARE FORECAST TO BE
ABOUT 30 METERS/10 DEGREES BELOW AVERAGE... AND THIS EQUATES TO
HIGHS 50 OF 55 DEGREES. A NW`RLY DOWNSLOPE WIND OF 15 TO 30 KTS AT
H85 AND THE INDICATION OF DRY ADIABATIC MIXING THROUGH H85 ON
FORECAST SOUNDINGS... YIELDS HIGHS A COUPLE OF DEGREES WARMER...
GENERALLY 53 TO 57 UNDER MOSTLY SUNNY SKIES. GIVEN THE RELATIVELY
DEEP MIXING AND STIFF H85 WINDS... A NORTHWESTERLY BREEZE OF 10 TO
15 MPH COULD GUST TO AROUND 25 MPH DURING THE AFTERNOON. SIMILAR LOW
LEVEL THICKNESSES TO SUNDAY MORNING BUT A LIGHT TO CALM WIND AND
CONTINUED CLEAR SKIES BENEATH THE RIDGE AXIS CENTERED OVER THE DEEP
SOUTH SUGGESTS LOWS 30 TO 35 DEGREES.
MONDAY: INCREASING LOWER TO MID LEVEL WAA AHEAD OF ANOTHER
AMPLIFYING TROUGH IN NW`RLY FLOW ALOFT WILL LIKELY SPREAD INCREASING
MID LEVEL MOISTURE ACROSS OUR REGION MONDAY. SOUTHWESTERLY FLOW
AHEAD OF A SURFACE COLD FRONT ATTENDANT THE UPPER TROUGH SUGGESTS
HIGHS SHOULD BE ABOUT A CATEGORY WARMER THAN THOSE OF SUNDAY...
ABOUT 55 TO 60 DEGREES.
&&
.LONG TERM /MONDAY NIGHT THROUGH FRIDAY/...
AS OF 245 PM FRIDAY...
AT KGSO...KRDU...AND KFAY...ONE HAS TO GO BACK TO MARCH 30 FOR THE
LAST DAY WHEN HIGHS DID NOT GET OUT OF THE 40S...AND TUESDAY IS A
DAY THERE STANDS A GOOD CHANCE OF THIS OCCURRING IN CENTRAL
NORTH CAROLINA AS THICKNESSES FALL COINCIDENT WITH A LONG-WAVE
TROUGH MOVING ACROSS THE STATE AND THE PRESENCE OF NORTHERLY
SURFACE FLOW. BOTH THE GFS AND THE ECMWF ARE CLOSE IN THE TIMING
OF THE TROUGH AND AT LEAST MODERATE...MAINLY CHANNELED VORTICITY
MOVING ACROSS THE STATE FROM LATE MONDAY NIGHT THROUGH TUESDAY. IN
GENERAL...THE GUIDANCE KEEPS THE FOCUS OF MID-LEVEL MOISTURE TO
THE NORTH OF CENTRAL NORTH CAROLINA...BUT JUST TO THE NORTH.
THICKNESSES ARE OBVIOUSLY COLD...AND THOUGH THE OVERALL AIR MASS
WILL BE DRY AND ANY PRECIPITATION LIKELY WOULD HAVE A VERY HARD
TIME MEASURING...WILL HAVE TO OBSERVE GUIDANCE TRENDS OVER THE
NEXT COUPLE OF DAYS OR SO TO ASSESS THE DEGREE OF MOISTURE ALOFT
AND THE STRENGTH OF MID-LEVEL SUPPORT. CURRENTLY...BOTH THE GFS
AND THE ECMWF ARE FOCUSING ON AVAILABLE MOISTURE PRIMARILY IN A
NARROW LAYER AROUND 700MB.
HEIGHTS BEGIN TO RISE QUICKLY LATE TUESDAY INTO WEDNESDAY. HOWEVER...
LIGHT WINDS EXPECTED AT THE SURFACE WITH FEW CLOUDS ANTICIPATED AT
THIS TIME SHOULD ALLOW OVERNIGHT LOWS TO FALL WELL INTO THE 20S ON
AVERAGE ACROSS CENTRAL NORTH CAROLINA TUESDAY NIGHT INTO WEDNESDAY
MORNING. TIMING OF SURFACE AND UPPER-LEVEL FEATURES THEN BEGINS TO
DIVERGE SOME LATE NEXT WEEK WITH THE 06Z GFS FASTER WITH THE
APPROACH AND PASSAGE OF A SURFACE COLD FRONT AND UPPER TROUGH
FRIDAY...WHILE THE ECMWF IS LATER...LATE FRIDAY INTO EARLY SATURDAY.
THE 12Z GFS HAS TRENDED SLOWER...MORE TOWARD THE ECMWF...THOUGH ONCE
AGAIN MOISTURE IS LIMITED THROUGHOUT THE OVERALL AIR MASS. WILL
CONTINUE TO KEEP THE FORECAST DRY FOR NOW ESPECIALLY OUT TO THE
SEVENTH DAY...THOUGH THICKNESSES ARE WARM. HIGHS SHOULD BE IN THE
50S FOR THURSDAY AND FRIDAY. BEYOND THIS PERIOD...THE LATEST GFS
HAS TRENDED TO A LESS AMPLIFIED SOLUTION WITH THE UPPER TROUGH IN
THE EASTERN CONUS WITH CORRESPONDINGLY HIGHER THICKNESSES AND
HEIGHTS. WHILE STILL ANTICIPATED TO BE BELOW NORMAL...TEMPERATURES
INTO NEXT WEEKEND MAY NOT BE QUITE AS COOL AS THOSE EXPECTED EARLY
IN THIS PART OF THE FORECAST.
&&
.AVIATION /06Z SATURDAY THROUGH WEDNESDAY/...
AS OF 125 AM SATURDAY...
THE WARM FRONT HAS ADVANCED NORTHWESTWARD INTO THE TRIAD AS OF 06Z
WITH AN ESE WIND NOW REPORTED AT KGSO AND KINT. FAIRLY LARGE AREA OF
CONVECTION ORIENTED S TO N PRESENTLY MOVING NE ACROSS MUCH OF
FORECAST AREA. THIS AREA OF CONVECTION IS IN RESPONSE TO LARGE SCALE
FORCING ACROSS THE SOUTHEAST FROM AN APPROACHING SHORT WAVE ACROSS
SOUTHERN AL/GA. NUMEROUS SHOWERS EMBEDDED THUNDERSTORMS WILL SWEEP
EAST ACROSS CENTRAL AND EASTERN TAF LOCATIONS THROUGH AROUND 10Z.
CIGS AND VSBY WILL VARY OVERNIGHT WITH LIFR/IFR CIGS AND VSBY
ASSOCIATED WITH THE PREVIOUSLY MENTIONED CONVECTION. SCATTERED
SHOWERS AND POSSIBLY A THUNDERSTORM IS POSSIBLE FOR THE REMAINDER OF
THE OVERNIGHT AND EARLY MORNING HOURS BEFORE ANOTHER AREA OF
WIDESPREAD CONVECTION SWEEPS EAST ON SAT MORNING AND EARLY AFTERNOON
ASSOCIATED WITH A COLD FRONT. CIGS AND VSBYS WILL IMPROVE TO MVFR
OUTSIDE OF THE CONVECTION.
0357Z AMDAR SOUNDING AT KRDU AND REPORTED A 29KT WIND AT AROUND 1500
FEET WITH A 0518Z AMDAR SOUNDING AT KGSO JUST BEFORE THE WARM
FRONTAL PASSAGE WITH A FAIRLY LIGHT WIND AT LESS THEN 15KTS UP TO
AROUND 2500 FEET JUMPS TO AROUND 50KTS AT 2500 FEET. WILL CONTINUE
TO EXCLUDE MENTION OF LLWS.
ON SATURDAY ANOTHER BAND OF SHOWERS AND SCATTERED THUNDERSTORMS...
WITH POTENTIALLY GUSTY WINDS IN EXCESS OF 40KT IN THE AFTERNOON.
THIS BAND OF CONVECTION IN THE AFTERNOON WILL BE ASSOCIATED WITH A
COLD FRONTAL PASSAGE. IFR TO MVFR CIGS EXPECTED THROUGHOUT THE
DAY... WITH MVFR VSBYS... REDUCING AT TIMES INTO THE LIFR CATEGORY
WITH HEAVY RAIN SHOWERS.
CIGS WILL RISE ABRUPTLY FROM MVFR TO VFR AFTER THE COLD FRONT PASSES
SATURDAY AFTERNOON ACROSS THE WEST AND IN THE LATE IN THE DAY ACROSS
THE EAST. WINDS WILL SHIFT TO THE WEST AT 15-25KT.
VFR CONDITIONS EXPECTED SUNDAY THROUGH TUESDAY.
&&
.RAH WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...JFB
NEAR TERM...JFB
SHORT TERM...MWS
LONG TERM...DJF
AVIATION...BLAES/BADGETT
AREA FORECAST DISCUSSION
NWS HOUSTON/GALVESTON TX
529 AM CST SAT NOV 15 2008
.DISCUSSION...
12Z TAF DISCUSSION.
&&
.AVIATION...
COLD FRONT HAS BLOWN THROUGH WHICH HAS CLEARED OUT THE SKIES.
MAIN CONCERN FOR THE DAY WILL BE STRONG NORTHERLY WINDS. MOST
AREAS WILL SEE WINDS 15-20KTS WITH GUSTS NEAR 25KTS. WINDS WILL
BE STRONGER ALONG THE COAST. VAD WIND PROFILE FROM THE 88D SHOWS
FAIRLY UNIFORM NORTHERLY WINDS. MAX WINDS STILL AT 4KFT LEVEL
WITH 50KTS. SUSPECT QUITE A BIT OF THIS IS MIXING DOWN AND WILL
CONTINUE TO DO SO. AS SUCH...PULLED LLWS FROM THE TAF BUT WILL
AMEND IF NECESSARY. WINDS SHOULD DIMINISH AFTER 00Z THIS EVENING
WITH WINDS LESS THAN 10 KTS OVERNIGHT.
39
&&
.PREV DISCUSSION... /ISSUED 518 AM CST SAT NOV 15 2008/
DISCUSSION...
STRONG RIDGE OF HIGH PRESSURE OVER COLORADO WILL PUSH SOUTHEAST
TODAY MAINTAINING THE STRONG NORTHERLY WINDS ACROSS SETX. STRONG
CAA WILL SEVERELY HAMPER THE RISE OF TEMPERATURES TODAY EVEN
THOUGH NEARLY FULL SUN WILL BE IN PLACE...AFTER THE MID CLOUDS
NEAR THE COAST EXIT. HIGHS TODAY WILL STRUGGLE TO GET BACK TO THE
LOWER TO MID 60S. NUMERICAL MODELS ARE FAIRLY CONSISTENT WITH
DROPPING 850 TEMPS TO 0 TO -2C BY 18Z AND 06Z ACARS/AMDAR DATA OUT
OF IAH LINED UP NICELY WITH PROGGED 850 TEMPS STRENGTHENING
CONFIDENCE IN THE AFTERNOON FORECAST WINDS AND TEMPERATURES.
WEAKENING CAA TONIGHT SHOULD LEAD TO A LIGHT FREEZE OVER THE
NORTHEASTERN HALF OF THE AREA BY SUNDAY MORNING. HIGH PRESSURE
OVERHEAD SUNDAY WILL WEAKEN IN PLACE TO BE FOLLOWED BY A GLANCING
BLOW OF A REINFORCING CANADIAN AIRMASS LATE MONDAY...THE COLDER
AIR WILL MOVE SOUTHEAST INTO OHIO VALLEY REGION AND EASTERN
SEABOARD RATHER THAN SOUTH AS THIS ONE TODAY HAS. THE STRONG UPPER
RIDGE TO THE WEST TODAY WILL GRADUALLY WEAKEN BY TUESDAY AND
WEDNESDAY AND THE JETSTREAM WILL HAVE RETREATED NORTHWARD.
INTRUSION OF VERY COLD AIR LATE NEXT WEEK WILL HAVE TROUBLE
PUSHING THIS FAR SOUTH AND GFS/ECMWF STILL DEPICT A MODIFIED FRONT
MOVING INTO SETX THURSDAY. FOR WHAT IT IS WORTH THAT FAR OUT THE
OPERATIONAL GFS LOOKS OUT OF PHASE IN COMPARISON TO THE ECMWF AND
THE GFS ENSEMBLE AS THEIR TREND IS ONE OF A WEAK TROUGH NEARING
THE NORTHWEST COAST WHEREAS THE OPERATIONAL IS FASTER AND SHARPER
ACROSS OR/CA.
45
MARINE...
THE COLD FRONT MADE IT TO THE 42019 BUOY AT AROUND 07Z AND FOR THE
LAST TWO OBS REPORTED SUSTAINED 31 KTS WITH GUSTS 37-39 KTS. SEAS
HAVE ONLY COME UP TO 6 FT BUT SUSPECT THAT SEAS NEAR 9-11 FT WILL BE
POSSIBLE GIVEN ENOUGH FETCH AND LONGEVITY OF THE WINDS. WHILE
BARELY MEETING GALE WARNING CRITERIA...WILL WANT TO CONTINUE TO HOLD
ONTO THE GALE WARNING FOR THE UPPER TX COASTAL WATERS OUT 20NM TO
60NM UNTIL 18Z-19Z WHEN WINDS SHOULD DROP BELOW 30 KTS. SCA FLAGS
WILL CONTINUE FOR THE WHOLE COAST UNTIL 00Z WHEN WINDS SHOULD DROP
BELOW 20 KTS FOR THE BAYS AND THEN 09Z SUN FOR THE 0NM TO 20NM
WATERS. SCA WILL LAST FOR THE OFFSHORE AREAS THROUGH 15Z SUN
ALTHOUGH IT IS POSSIBLE FOR WINDS TO DROP BELOW CRITERIA BEFORE
THEN. OTHERWISE...HIGH PRESSURE SHOULD SETTLE OVER THE AREA SUN
INTO MON WITH LIGHT WINDS. SEAS SHOULD SUBSIDE DURING THIS TIME AS
WELL. A COUPLE OF WEAK COLD FRONTS SHOULD PUSH OFF THE COAST ON
TUESDAY AND AGAIN ON THURSDAY. THIS MAY CAUSE A BRIEF INCREASE IN
WINDS AND SEAS BUT ADVISORY FLAGS ARE NOT EXPECTED.
39
FIRE WEATHER...
AIRMASS MOVING INTO SE TX TODAY APPEARS TO BE RATHER DRY WITH
DEWPOINT TEMPS IN N TX IN THE MID 20S. THIS AIRMASS SHOULD MOVE
INTO SE TX TODAY AND AFTERNOON RELATIVE HUMIDITY LEVELS SHOULD DROP
INTO THE LOW 20S...POSSIBLY LOWER. WINDS WILL REMAIN STRONG FROM
THE NORTH IN THE 15 TO 25 MPH RANGE. WHILE FUEL MOISTURE WILL BE ON
THE HIGH SIDE GIVEN RECENT RAINFALL ACROSS THE AREA...THE
COMBINATION OF LOW RH AND STRONG NORTHERLY WINDS WILL RESULT IN
HAZARDOUS FIRE WEATHER CONDITIONS. A RED FLAG WARNING WILL BE ISSUED
FOR MUCH OF SOUTHEAST TEXAS FOR TODAY.
39
&&
.PRELIMINARY POINT TEMPS/POPS...
COLLEGE STATION (CLL) 62 33 68 38 73 / 0 0 0 0 0
HOUSTON (IAH) 63 34 66 38 72 / 0 0 0 0 0
GALVESTON (GLS) 63 46 63 52 69 / 0 0 0 0 0
&&
.HGX WATCHES/WARNINGS/ADVISORIES...
TX...RED FLAG WARNING FROM 9 AM THIS MORNING TO 6 PM CST THIS
AFTERNOON FOR THE FOLLOWING ZONES: AUSTIN...BRAZORIA...
BRAZOS...BURLESON...CHAMBERS...COLORADO...FORT BEND...
GALVESTON...GRIMES...HARRIS...HOUSTON...JACKSON...LIBERTY...
MADISON...MATAGORDA...MONTGOMERY...POLK...SAN JACINTO...
TRINITY...WALKER...WALLER...WASHINGTON...WHARTON.
WIND ADVISORY UNTIL 3 PM CST THIS AFTERNOON FOR THE FOLLOWING
ZONES: BRAZORIA...CHAMBERS...GALVESTON...JACKSON...
MATAGORDA.
GM...SMALL CRAFT ADVISORY UNTIL 6 PM CST THIS AFTERNOON FOR THE
FOLLOWING ZONES: GALVESTON BAY...MATAGORDA BAY.
SMALL CRAFT ADVISORY UNTIL 3 AM CST SUNDAY FOR THE FOLLOWING
ZONES: WATERS FROM FREEPORT TO THE MATAGORDA SHIP CHANNEL
OUT 20 NM...WATERS FROM HIGH ISLAND TO FREEPORT OUT 20 NM.
SMALL CRAFT ADVISORY FROM 1 PM THIS AFTERNOON TO 9 AM CST SUNDAY
FOR THE FOLLOWING ZONES: WATERS FROM FREEPORT TO THE
MATAGORDA SHIP CHANNEL 20 NM TO 60 NM...WATERS FROM HIGH
ISLAND TO FREEPORT 20 TO 60 NM.
GALE WARNING UNTIL 1 PM CST THIS AFTERNOON FOR THE FOLLOWING
ZONES: WATERS FROM FREEPORT TO THE MATAGORDA SHIP CHANNEL
20 NM TO 60 NM...WATERS FROM HIGH ISLAND TO FREEPORT 20 TO
60 NM.
&&
$$
DISCUSSION...45
AVIATION/MARINE...39
AREA FORECAST DISCUSSION
NWS HOUSTON/GALVESTON TX
518 AM CST SAT NOV 15 2008
.DISCUSSION...
STRONG RIDGE OF HIGH PRESSURE OVER COLORADO WILL PUSH SOUTHEAST
TODAY MAINTAINING THE STRONG NORTHERLY WINDS ACROSS SETX. STRONG
CAA WILL SEVERELY HAMPER THE RISE OF TEMPERATURES TODAY EVEN
THOUGH NEARLY FULL SUN WILL BE IN PLACE...AFTER THE MID CLOUDS
NEAR THE COAST EXIT. HIGHS TODAY WILL STRUGGLE TO GET BACK TO THE
LOWER TO MID 60S. NUMERICAL MODELS ARE FAIRLY CONSISTENT WITH
DROPPING 850 TEMPS TO 0 TO -2C BY 18Z AND 06Z ACARS/AMDAR DATA OUT
OF IAH LINED UP NICELY WITH PROGGED 850 TEMPS STRENGTHENING
CONFIDENCE IN THE AFTERNOON FORECAST WINDS AND TEMPERATURES.
WEAKENING CAA TONIGHT SHOULD LEAD TO A LIGHT FREEZE OVER THE
NORTHEASTERN HALF OF THE AREA BY SUNDAY MORNING. HIGH PRESSURE
OVERHEAD SUNDAY WILL WEAKEN IN PLACE TO BE FOLLOWED BY A GLANCING
BLOW OF A REINFORCING CANADIAN AIRMASS LATE MONDAY...THE COLDER
AIR WILL MOVE SOUTHEAST INTO OHIO VALLEY REGION AND EASTERN
SEABOARD RATHER THAN SOUTH AS THIS ONE TODAY HAS. THE STRONG UPPER
RIDGE TO THE WEST TODAY WILL GRADUALLY WEAKEN BY TUESDAY AND
WEDNESDAY AND THE JETSTREAM WILL HAVE RETREATED NORTHWARD.
INTRUSION OF VERY COLD AIR LATE NEXT WEEK WILL HAVE TROUBLE
PUSHING THIS FAR SOUTH AND GFS/ECMWF STILL DEPICT A MODIFIED FRONT
MOVING INTO SETX THURSDAY. FOR WHAT IT IS WORTH THAT FAR OUT THE
OPERATIONAL GFS LOOKS OUT OF PHASE IN COMPARISON TO THE ECMWF AND
THE GFS ENSEMBLE AS THEIR TREND IS ONE OF A WEAK TROUGH NEARING
THE NORTHWEST COAST WHEREAS THE OPERATIONAL IS FASTER AND SHARPER
ACROSS OR/CA.
45
&&
.MARINE...
THE COLD FRONT MADE IT TO THE 42019 BUOY AT AROUND 07Z AND FOR THE
LAST TWO OBS REPORTED SUSTAINED 31 KTS WITH GUSTS 37-39 KTS. SEAS
HAVE ONLY COME UP TO 6 FT BUT SUSPECT THAT SEAS NEAR 9-11 FT WILL BE
POSSIBLE GIVEN ENOUGH FETCH AND LONGEVITY OF THE WINDS. WHILE
BARELY MEETING GALE WARNING CRITERIA...WILL WANT TO CONTINUE TO HOLD
ONTO THE GALE WARNING FOR THE UPPER TX COASTAL WATERS OUT 20NM TO
60NM UNTIL 18Z-19Z WHEN WINDS SHOULD DROP BELOW 30 KTS. SCA FLAGS
WILL CONTINUE FOR THE WHOLE COAST UNTIL 00Z WHEN WINDS SHOULD DROP
BELOW 20 KTS FOR THE BAYS AND THEN 09Z SUN FOR THE 0NM TO 20NM
WATERS. SCA WILL LAST FOR THE OFFSHORE AREAS THROUGH 15Z SUN
ALTHOUGH IT IS POSSIBLE FOR WINDS TO DROP BELOW CRITERIA BEFORE
THEN. OTHERWISE...HIGH PRESSURE SHOULD SETTLE OVER THE AREA SUN
INTO MON WITH LIGHT WINDS. SEAS SHOULD SUBSIDE DURING THIS TIME AS
WELL. A COUPLE OF WEAK COLD FRONTS SHOULD PUSH OFF THE COAST ON
TUESDAY AND AGAIN ON THURSDAY. THIS MAY CAUSE A BRIEF INCREASE IN
WINDS AND SEAS BUT ADVISORY FLAGS ARE NOT EXPECTED.
39
&&
.FIRE WEATHER...
AIRMASS MOVING INTO SE TX TODAY APPEARS TO BE RATHER DRY WITH
DEWPOINT TEMPS IN N TX IN THE MID 20S. THIS AIRMASS SHOULD MOVE
INTO SE TX TODAY AND AFTERNOON RELATIVE HUMIDITY LEVELS SHOULD DROP
INTO THE LOW 20S...POSSIBLY LOWER. WINDS WILL REMAIN STRONG FROM
THE NORTH IN THE 15 TO 25 MPH RANGE. WHILE FUEL MOISTURE WILL BE ON
THE HIGH SIDE GIVEN RECENT RAINFALL ACROSS THE AREA...THE
COMBINATION OF LOW RH AND STRONG NORTHERLY WINDS WILL RESULT IN
HAZARDOUS FIRE WEATHER CONDITIONS. A RED FLAG WARNING WILL BE ISSUED
FOR MUCH OF SOUTHEAST TEXAS FOR TODAY.
39
&&
.PRELIMINARY POINT TEMPS/POPS...
COLLEGE STATION (CLL) 62 33 68 38 73 / 0 0 0 0 0
HOUSTON (IAH) 63 34 66 38 72 / 0 0 0 0 0
GALVESTON (GLS) 63 46 63 52 69 / 0 0 0 0 0
&&
.HGX WATCHES/WARNINGS/ADVISORIES...
TX...RED FLAG WARNING FROM 9 AM THIS MORNING TO 6 PM CST THIS
AFTERNOON FOR THE FOLLOWING ZONES: AUSTIN...BRAZORIA...
BRAZOS...BURLESON...CHAMBERS...COLORADO...FORT BEND...
GALVESTON...GRIMES...HARRIS...HOUSTON...JACKSON...LIBERTY...
MADISON...MATAGORDA...MONTGOMERY...POLK...SAN JACINTO...
TRINITY...WALKER...WALLER...WASHINGTON...WHARTON.
WIND ADVISORY UNTIL 3 PM CST THIS AFTERNOON FOR THE FOLLOWING
ZONES: BRAZORIA...CHAMBERS...GALVESTON...JACKSON...
MATAGORDA.
GM...SMALL CRAFT ADVISORY UNTIL 6 PM CST THIS AFTERNOON FOR THE
FOLLOWING ZONES: GALVESTON BAY...MATAGORDA BAY.
SMALL CRAFT ADVISORY UNTIL 3 AM CST SUNDAY FOR THE FOLLOWING
ZONES: WATERS FROM FREEPORT TO THE MATAGORDA SHIP CHANNEL
OUT 20 NM...WATERS FROM HIGH ISLAND TO FREEPORT OUT 20 NM.
SMALL CRAFT ADVISORY FROM 1 PM THIS AFTERNOON TO 9 AM CST SUNDAY
FOR THE FOLLOWING ZONES: WATERS FROM FREEPORT TO THE
MATAGORDA SHIP CHANNEL 20 NM TO 60 NM...WATERS FROM HIGH
ISLAND TO FREEPORT 20 TO 60 NM.
GALE WARNING UNTIL 1 PM CST THIS AFTERNOON FOR THE FOLLOWING
ZONES: WATERS FROM FREEPORT TO THE MATAGORDA SHIP CHANNEL
20 NM TO 60 NM...WATERS FROM HIGH ISLAND TO FREEPORT 20 TO
60 NM.
&&
$$
DISCUSSION...45
AVIATION/MARINE...39
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