Forecast Discussions mentioning any of
"HRRR" "RAP" "RR" "RUC13" "RUC" received at GSD on 01/15/13
AREA FORECAST DISCUSSION
NWS DENVER/BOULDER CO
742 PM MST MON JAN 14 2013
.UPDATE...EXCEPT FOR LOW CLOUDS OVER EASTERN COLORADO...SKIES ARE
MOSTLY CLEAR OVER THE FORECAST AREA. THIS WILL ALLOW TEMPERATURES
TO PLUMMET THIS EVENING...ESPECIALLY IN THE MOUNTAIN VALLEYS.
READINGS IN THE MOUNTAINS VALLEYS ARE ALREADY IN THE -10 TO -20
RANGE. WOULD EXPECT A FEW LOCATIONS TO GET CLOSE TO -30 BEFORE
HIGHS CLOUDS INCREASE AROUND MIDNIGHT. EXPECT TEMPERATURES TO THEN
LEVEL OFF AS THE HIGH CLOUDS ENTER THE STATE FROM THE NORTH. WILL
MAKE ADJUSTMENTS TO THE FORECAST TO REFLECT CURRENT CONDITIONS...
WHICH WILL BE MAINLY TO TEMPERATURES.
&&
.AVIATION...MOSTLY CLEAR SKIES WILL PREVAIL THROUGH 06Z THEN HIGH
CLOUDS WILL INCREASE. NORMAL SOUTHERLY DRAINAGE WINDS WILL PREVAIL
THROUGH THE NIGHT AT KDEN AND KAPA. WESTERLY DRAINAGE WINDS WILL
OCCUR AT KBJC.
&&
.PREV DISCUSSION... /ISSUED 355 PM MST MON JAN 14 2013/
SHORT TERM...ELONGATED UPPER TROUGH CURRENTLY MOVING ACROSS
STATE. LATEST RUC QG VERTICAL VELOCITY ANALYSIS SHOWING SOME
LINGERING MID LEVEL ASCENT ACROSS FAR EASTERN PLAINS. CURRENT
SURFACE OBS AND WEB CAMS DO NOT SHOW SNOW OVER THE AREA THOUGH
LATEST SATELLITE INDICATE A DECENT BATCH OF LOW CLOUDS. ACROSS
MOUNTAINS...WEB CAMS SHOW LIGHT SNOW ALONG THE CONTINENTAL DIVIDE
AND PERHAPS OVER THE GORE AND PARK RANGES OF WESTERN JACKSON
COUNTY. MODELS SHOW THE ASCENT MOVING INTO KANSAS DURING THE
EVENING...SHOULD SEE ANY LINGERING SNOW ACROSS THE PLAINS ENDING
AT THAT TIME. MOISTURE DOES INCREASE OVER MOUNTAINS ON BACK SIDE
OF TROUGH OVERNIGHT...SHOULD SEE SNOW CHANCES INCREASE
PARTICULARLY ZONE 31. WINDS LOOK TO INCREASE AS WELL OVER THE
RIDGES WHICH SHOULD HELP MODERATE THE TEMPERATURES IN AND NEAR
FOOTHILLS. WIND CHILL READINGS TO BE WELL BELOW ZERO...BUT SHOULD
REMAIN BELOW WARNING CRITERIA. OTHERWISE...A COLD NIGHT IS
EXPECTED WITH TEMPERATURES SIMILAR TO THIS MORNINGS READINGS. ON
TUESDAY...THE TROUGH WILL BE IN KANSAS BY 18Z WITH NORTHERLY FLOW
ALOFT OVER COLORADO. THIS SHOULD CONTINUE TO PROVIDE A CHANCE OF
SNOW TO THE MOUNTAINS... MAINLY ZONES 31 AND 33. SNOW AMOUNTS TO
REMAIN LIGHT. ACROSS PLAINS...DRY CONDITIONS TO PREVAIL WITH A
GRADUAL INCREASE IN MID LEVEL CLOUDS. GRADUAL WARMING TREND IS
EXPECTED AS WARM AIR ADVECTS INTO AREA. HOWEVER...INVERSIONS WILL
LIMIT WARMUP IN MOUNTAIN VALLEYS AND LOW LYING AREAS OF THE
PLAINS. ALSO MID LEVEL CLOUDS WILL HINDER WARMUP. CURRENT
TEMPERATURE GRIDS LOOK REASONABLE.
LONG TERM...THE STRONG NORTH-NORTHEASTERLY FLOW ALOFT IS ON THE
DECREASE TUESDAY NIGHT. ON WEDNESDAY...THE FLOW ALOFT CONTINUES
TO WEAKEN AND BECOMES NORTHWESTERLY. VERY WEAK WEST-NORTHWESTERLY
FLOW ALOFT IS PROGGED WEDNESDAY NIGHT THROUGH THURSDAY NIGHT.
THERE IS BENIGN SYNOPTIC SCALE ENERGY PROGGED ON THE QG VERTICAL
VELOCITY FIELDS THROUGH THE FIVE PERIODS. THE LEVEL FLOW WILL
LIKELY BE A MIX OF NORMAL DIURNAL TRENDS WITH SOME NORTHWESTERLY
DOWNSLOPING THROWN IN TUESDAY NIGHT INTO WEDNESDAY EVENING.
NORMALS PATTERNS ARE LIKELY BY THURSDAY AND THURSDAY NIGHT. FOR
MOISTURE...IT IS PRETTY DEEP TUESDAY EVENING...THEN MOISTURE
DECREASES TOWARDS WEDNESDAY MORNING. FROM WEDNESDAY THROUGH
THURSDAY NIGHT THERE IS VERY LITTLE MOISTURE OVER THE CWA. THERE
IS A TAD OF MEASURABLE SNOWFALL PROGGED ON THE QPF FIELDS TUESDAY
EVENING...THEN NOTHING THROUGH THE REST OF THE PERIODS. FOR POPS
WILL GO WITH 20-50%S FOR THE MOUNTAINS TUESDAY NIGHT...AND 5-20%S
FOR THE PLAINS. FROM WEDNESDAY ONWARD NO POPS. FOR TEMPERATURES
..WEDNESDAY`S HIGHS ARE UP 7-9 C FROM TUESDAY`S. THURSDAY`S HIGHS
ARE SIMILAR TO WEDNESDAY`S. FOR THE LATER DAYS...FRIDAY THROUGH
MONDAY...THE MEDIUM RANGE MODELS KEEP THE FORECAST AREA
IN...MOSTLY...WEAK NORTHWESTERLY FLOW ALOFT ALL FOUR DAYS. A MEAN
TROUGH EAST OF THE CWA GETS A LITTLE CLOSER TO THE CWA...COMPARED
TO PREVIOUS RUNS. THE GFS BRINGS A COLDER AIRMASS INTO THE CWA
SATURDAY AND SUNDAY...THE ECMWF DOES NOT. BOTH MODELS KEEP THE CWA
DRY.
AVIATION...CEILINGS HAVE SCATTERED OUT AT DEN THOUGH SOME HAZE
STILL IN THE AREA. VFR CONDITIONS TO PREVAIL WITH UNLIMITED
CEILINGS. LIGHT NORTHERLY WINDS TO BECOME SOUTHERLY AS DRAINAGE
PATTERN DEVELOPS. ANY FOG THAT DEVELOPS SHOULD BE CONFINED TO THE
LOW LYING AREAS IN WELD COUNTY. ON TUESDAY...WINDS TO BECOME
NORTHWEST WITH SPEEDS LESS THAN 8 KTS. GRADUAL INCREASE IN MID
LEVEL CLOUDS WITH CEILINGS ABOVE 10000 FEET.
&&
.BOU WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...D-L
LONG TERM....RJK
AVIATION...MEIER
AREA FORECAST DISCUSSION
NWS TAMPA BAY RUSKIN FL
145 PM EST SUN JAN 13 2013
.SHORT TERM (THIS EVENING THROUGH TUESDAY NIGHT)...
18Z WATER VAPOR AND H4 RAP ANALYSIS SHOWS A HIGHLY AMPLIFIED UPPER
LEVEL PATTERN REMAINS IN PLACE OVER THE CONUS. PATTERN CONSISTS OF A
LARGE AND IMPRESSIVE LONGWAVE TROUGH OVER THE WESTERN 2/3RDS OF THE
CONUS FOLLOWED DOWNSTREAM BY LONGWAVE RIDGING EXTENDING FROM THE
EASTERN GULF OF MEXICO NORTHWARD ALONG THE ATLANTIC SEABOARD. THE
DOMINANT WESTERN TROUGH IS BEGINNING TO WIN THE OVERALL BATTLE AND
WE WILL SEE THE NORTHERN PORTION OF THE EASTERN RIDGE QUICKLY BREAK
DOWN OVER THE NEXT 24 HOURS. LUCKILY FOR THOSE WITH OUTDOOR
PLANS...GLOBAL GUIDANCE IS IN GOOD AGREEMENT THAT THE RIDGE WILL
HOLD STRONG THROUGH TUESDAY OVER OUR HEADS...KEEPING OUR LOCAL
WEATHER CONTINUED GENERALLY DRY AND UNSEASONABLY WARM.
AT THE SURFACE...HIGH PRESSURE CENTERED OFF THE NORTHEAST FLORIDA
COAST CONTINUES TO RIDGE BACK TO THE WEST ACROSS NORTHERN PORTIONS
OF THE STATE. THIS RIDGE AXIS IS EXPECTED TO SETTLE A BIT FURTHER
SOUTH THE NEXT DAY OR 2. THE WEAKER GRADIENT AND CONTINUED STRONG
SURFACE HEATING WILL LEAD TO BETTER CHANCES FOR FEEBLE AFTERNOON
SEA-BREEZES NEAR THE COAST...ESPECIALLY ALONG THE NATURE COAST WHERE
THE LAND/SEA TEMP GRADIENT REMAINS THE GREATEST. MAY BE A BIT COOLER
THE NEXT FEW AFTERNOON ALONG THE IMMEDIATE COAST OF THE NATURE COAST
DO TO THIS ONSHORE FLOW.
12Z KTBW SOUNDING PROFILE CONTINUED TO SHOW THE INFLUENCE OF THE
UPPER RIDGE WITH A SUBSIDENCE INVERSION AROUND 850MB...AND A DRY
COLUMN ABOVE. MOISTURE LEVELS INCREASE NEAR THE TOP OF THE COLUMN IN
THE FORM OF SOME "WISPY" CIRRUS TRYING TO OVERSPREAD FROM THE WEST.
SO FAR...MUCH OF THIS CIRRUS HAS BEEN EVAPORATING AS IT APPROACHES
THE SUPPRESSION OF THE RIDGE AXIS.
&&
.LONG TERM (TUESDAY NIGHT THROUGH SATURDAY)...LARGE HIGH PRESSURE
DOME OVER THE BAHAMAS AND FL WILL FINALLY BE NUDGED EAST LATE IN THE
PERIOD AS A DETACHED TROUGH OVER TX IS REABSORBED WHILE IT MOVES
EAST AND WEAKENS. IT APPEARS THIS WILL FINALLY LET A WEAK FRONTAL
BOUNDARY TO MOVE INTO THE REGION BRINGING A SLT CHANCE OF SHOW SHRA
MAINLY ACROSS CEN AND NRN ZONES. ECMWF IS MUCH MORE MOIST THAN THE
GFS...BUT GIVEN UNCERTAINTY WILL STICK WITH JUST 20 POPS ATTM FOR
THU THROUGH SAT TIMEFRAME FOR NOW. TEMPS WILL CONTINUE WELL ABOVE
NORMAL...ALTHOUGH A SLIGHT DECREASE IN HIGHS WILL OCCUR GIVEN
INCREASING MOISTURE AND THEN THE FRONTAL BOUNDARY IN THE AREA WILL
OCCUR THROUGH THE PERIOD. WHAT HAPPENS BEYOND THE FORECAST PERIOD
IS MORE INTERESTING AS IT APPEARS A HIGHLY AMPLIFIED PATTERN WILL
DEVELOP WITH MORE OF AN ERN US TROUGH THIS GO AROUND. THIS MEANS A
RETURN TO WINTER MAY BE IN STORE BEYOND THE CURRENT FORECAST PERIOD.
&&
.AVIATION...
EXPECTING VFR CONDITIONS TO PREVAIL FOR THE NEXT 24 HOURS. SOME FOG
MAY BRING MVFR VISIBILITIES TO LAL AND PGD BETWEEN 08Z AND 14Z...
BUT THINK STRATOCUMULUS CLOUDS WILL LIMIT RADIATIONAL COOLING
NECESSARY FOR MORE WIDESPREAD FOG DEVELOPMENT.
&&
.MARINE...
HIGH PRESSURE CENTERED OFF THE SOUTHEAST COAST WILL CONTINUE TO
RIDGE BACK TO THE WEST ACROSS THE FLORIDA PENINSULA AND NORTHEAST
GULF OF MEXICO THROUGH TUESDAY. THIS RIDGE WILL WEAKEN AND SHIFT
EAST BY WEDNESDAY AS A WEAK COLD FRONT APPROACHES FROM THE NORTH.
THIS FRONT IS EXPECTED TO ARRIVE ACROSS THE EASTERN GULF OF MEXICO
DURING THURSDAY.
&&
.FIRE WEATHER...
HIGH PRESSURE REMAINS IN CONTROL OF THE FORECAST AREA THROUGH
TUESDAY WITH A STABLE...GENERALLY DRY...AND UNSEASONABLY WARM
AIRMASS. DESPITE THE ABOVE NORMAL DAYTIME TEMPERATURES...THERE WILL
BE ENOUGH LOW LEVEL MOISTURE TO PREVENT ANY WIDESPREAD AREAS OF
CRITICALLY LOW RELATIVE HUMIDITY. THE NEXT COLD FRONT IS NOT
ANTICIPATED TO ARRIVE UNTIL MID-WEEK AND PROVIDE ONLY A SLIGHT
CHANCE OF A FEW SHOWERS.
&&
.PRELIMINARY POINT TEMPS/POPS...
TPA 64 79 63 78 / 10 0 10 10
FMY 62 80 63 81 / 0 0 10 10
GIF 59 81 59 81 / 0 0 10 10
SRQ 62 78 60 78 / 0 0 10 10
BKV 56 81 54 81 / 10 0 10 10
SPG 65 78 64 77 / 0 0 10 10
&&
.TBW WATCHES/WARNINGS/ADVISORIES...
FL...NONE.
GULF WATERS...NONE.
&&
$$
SHORT TERM/MARINE/FIRE WX...MROCZKA
AVIATION...JILLSON
LONG TERM...GITTINGER
AREA FORECAST DISCUSSION...CORRECTED
NWS TAMPA BAY RUSKIN FL
1040 AM EST SUN JAN 13 2013
.UPDATE (REST OF TODAY THROUGH TUESDAY)...
15Z WATER VAPOR AND H4 RAP ANALYSIS SHOWS A HIGHLY AMPLIFIED UPPER
LEVEL PATTERN REMAINS IN PLACE OVER THE CONUS. PATTERN CONSISTS OF A
LARGE AND IMPRESSIVE LONGWAVE TROUGH OVER THE WESTERN 2/3RDS OF THE
CONUS FOLLOWED DOWNSTREAM BY LONGWAVE RIDGING EXTENDING FROM THE
EASTERN GULF OF MEXICO NORTHWARD ALONG THE ATLANTIC SEABOARD. THE
DOMINANT WESTERN TROUGH IS BEGINNING TO WIN THE OVERALL BATTLE AND
WE WILL SEE THE NORTHERN PORTION OF THE EASTERN RIDGE QUICKLY BREAK
DOWN OVER THE NEXT 24 HOURS. LUCKILY FOR THOSE WITH OUTDOOR
PLANS...GLOBAL GUIDANCE IS IN GOOD AGREEMENT THAT THE RIDGE WILL
HOLD STRONG THROUGH TUESDAY OVER OUR HEADS AND KEEP OUR WEATHER
CONTINUED DRY AND UNSEASONABLY WARM.
AT THE SURFACE...HIGH PRESSURE CENTERED OFF THE NORTHEAST FLORIDA
COAST CONTINUES TO RIDGE BACK TO THE WEST ACROSS NORTHERN PORTIONS
OF THE STATE. THIS RIDGE AXIS IS EXPECTED TO SETTLE A BIT FURTHER
SOUTH THE NEXT DAY OR 2. THE WEAKER GRADIENT AND CONTINUED STRONG
SURFACE HEATING WILL LEAD TO BETTER CHANCES FOR FEEBLE AFTERNOON
SEA-BREEZES NEAR THE COAST...ESPECIALLY ALONG THE NATURE COAST WHERE
THE LAND/SEA TEMP GRADIENT REMAINS THE GREATEST. MAY BE A BIT COOLER
THE NEXT FEW AFTERNOON ALONG THE IMMEDIATE COAST OF THE NATURE COAST
DO TO THIS ONSHORE FLOW.
12Z KTBW SOUNDING PROFILE CONTINUES TO SHOW THE INFLUENCE OF THE
UPPER RIDGE WITH A SUBSIDENCE INVERSION AROUND 850MB...AND A DRY
COLUMN ABOVE. MOISTURE LEVELS INCREASE NEAR THE TOP OF THE COLUMN IN
THE FORM OF SOME "WISPY" CIRRUS TRYING TO OVERSPREAD FROM THE WEST.
SO FAR...MUCH OF THIS CIRRUS HAS BEEN EVAPORATING AS IT APPROACHES
THE SUPPRESSION OF THE RIDGE AXIS. LIKELY WILL SEE THIS TREND
CONTINUE...AND WE CAN CONSIDER SKIES REMAINING A FILTERED PARTLY TO
MOSTLY SUNNY THROUGH THE AFTERNOON.
OVERALL THE SYNOPTIC PATTERN WILL HOLD THROUGH TUESDAY AND SEE
LITTLE REASON TO MAKE SIGNIFICANT CHANGES TO THE INHERITED FORECAST
AT THIS TIME.
&&
.AVIATION...
VFR TODAY WITH MAINLY INCREASING HIGH CLOUDS. SOME PATCHY FOG
POSSIBLE MONDAY MORNING ESPECIALLY AT FOG PRONE PGD.
&&
.MARINE...
HIGH PRESSURE CENTERED OFF THE SOUTHEAST COAST WILL CONTINUE TO
RIDGE BACK TO THE WEST ACROSS THE FLORIDA PENINSULA AND NORTHEAST
GULF OF MEXICO THROUGH TUESDAY. THIS RIDGE WILL WEAKEN AND SHIFT
EAST BY WEDNESDAY AS A WEAK COLD FRONT APPROACHES FROM THE NORTH.
THIS FRONT IS EXPECTED TO ARRIVE ACROSS THE EASTERN GULF OF MEXICO
DURING THURSDAY.
&&
.PRELIMINARY POINT TEMPS/POPS...
TPA 81 64 79 61 / 0 10 0 10
FMY 84 62 80 62 / 0 0 0 10
GIF 82 59 81 59 / 0 0 0 10
SRQ 81 62 78 60 / 0 0 0 10
BKV 83 56 81 53 / 0 10 0 10
SPG 80 65 78 64 / 0 0 0 10
&&
.TBW WATCHES/WARNINGS/ADVISORIES...
FL...NONE.
GULF WATERS...NONE.
&&
$$
UPDATE/MARINE...MROCZKA
AVIATION...JILLSON
AREA FORECAST DISCUSSION
NWS JACKSONVILLE FL
417 AM EST SUN JAN 13 2013
...DENSE FOG ADVY FOR PARTS OF THE AREA THIS MORNING...
...NEAR RECORD WARMTH THROUGH TUESDAY...
.CURRENTLY...LATEST RAP ANALYSIS SHOWS 500 MB HIGH PRES RIDGE LOCATED
OVER WRN ATLC ALONG ABOUT 75W. SFC HIGH PRES APPEARS TO BE LOCATED
NEAR 30N75W. ONCE AGAIN...HIGH DEWPOINT AIR IN THE LOWER 60S TO THE
UPPER 50S IS RESULTING IN EARLY MORNING FOG DEVELOPMENT...INITIALLY
THAT FORMED ALONG THE COAST THAT IS SEA FOG. DENSE FOG ADVY WAS
ISSUED EARLIER TO ACCOUNT FOR LOW VISIBILITIES OVER THE IMMEDIATE
COASTAL AREAS NORTH OF FERNANDINA BEACH. THIS ADVISORY MAY BE
EXPANDED IN COVERAGE.
.SHORT TERM...TODAY THROUGH MONDAY...
EARLY MORNING FOG EXPECTED THAT SHOULD DISSIPATE BY AROUND 14Z-15Z
INSOLATION BURNS IT OFF. IN FACT...IT MAY DISSIPATE FASTER THAN
YESTERDAY GIVEN THE SHALLOWNESS OF THE MOISTURE PER NAM BUFR
SOUNDINGS. HOWEVER...SEA FOG SHOULD PERSIST LONGER OVER THE SE GA
MARINE WATERS FROM 0-20 NM THROUGH THE EARLY AFTN. OTHERWISE..THE
STAGNANT WX PATTERN FEATURING THE DEEP LAYER HIGH PRES TO OUR E WILL
CONTINUE THE ABOVE NORMAL TEMPS TODAY...SIMILAR TO YESTERDAY...WITH
MID 70S NEAR THE COAST AND NEAR OR JUST ABOVE 80 DEG INLAND. WENT
JUST ABOVE GUIDANCE BASED ON PERSISTENCE. RECORD HIGHS POSSIBLE AT
ALMA AND JAX TODAY WHERE THEY ARE CURRENTLY 80 AND 82 DEGREES
RESPECTIVELY. E COAST SEA BREEZE EXPECTED ONCE AGAIN IN THE
AFTN...AND SHOULD MOVE WELL INLAND LIKE THE PAST COUPLE OF DAYS.
TONIGHT...AN ONSHORE FLOW IN THE EVENING WILL ENSURE THE BOUNDARY
LAYER AIRMASS WILL REMAIN MOIST. AREAS OF FOG EXPECTED TO DEVELOP
AGAIN BUT SHOULD AGAIN BE MORE COMMON ACROSS ERN PARTS OF SE GA AND
NE FL WHERE A SHARPER INVERSION IS EXPECTED. DENSE FOG WILL BE
POSSIBLE BUT A FEW STRATO CLDS MAY SERVE TO KEEP IT CONFINED TO
SMALL AREAS. MONDAY...SFC RIDGE WILL SHIFT A BIT FURTHER S ACROSS S
CENTRAL FL WHILE A SLOW MOVING COLD FRONT MOVES INTO N CENTRAL GA TO
SRN AL. THE STOUT RIDGE KEEP OUR AREA DRY WITH DEEP S AND SW FLOW
AND WARM TEMPS AGAIN. HIGHS AROUND 80 INLAND AND MID 70S NEAR THE
COAST. E COAST SEA BREEZE WILL GET A LITTLE LATER START DUE TO
SLIGHTLY STRONGER S-SW WINDS.
.LONG TERM /TUESDAY THROUGH SATURDAY/...
THIS PERIOD WILL FEATURE A TRANSITION FROM UNSEASONABLY WARM AND
DRY CONDITIONS TO CLOUDY AND COOL CONDITIONS WITH RAIN SHOWERS BY
THURSDAY. HIGH PRESSURE WILL REMAIN THE DOMINANT FEATURE THROUGH
TUESDAY NIGHT AND WE HAVE REMOVED ALL MENTION OF POPS AND KEPT ALL
AREAS DRY THROUGH THIS PERIOD. TEMPERATURES WILL REMAIN WELL ABOVE
NORMAL THROUGH WEDNESDAY.
THE MODELS HAVE REALLY COME INTO EXCELLENT AGREEMENT WITH REGARDS
TO THE SYNOPTIC PATTERN ON WEDNESDAY AND THURSDAY...THUS RESULTING
IN AN INCREASE IN FORECAST CONFIDENCE. A SLOW MOVING COLD FRONT
WILL STRUGGLE TO CUT INTO THE RIDGE UNTIL THE NEXT UPPER WAVE
PIVOTS ACROSS THE DEEP SOUTH WEDNESDAY NIGHT INTO THURSDAY. THIS
WILL FINALLY BE ENOUGH TO PUSH THE FRONT SOUTH...PUSHING THROUGH
SOUTHEAST GEORGIA WEDNESDAY NIGHT AND THEN THROUGH NORTHERN
FLORIDA ON THURSDAY. BOTH GFS AND ECMWF HAVE TRENDED TOWARDS A
WETTER SOLUTION WITH THE FRONTAL PASSAGE...PARTICULARLY ON
THURSDAY AS THE UPPER SUPPORT INCREASES WITH THE UPPER WAVE. WILL
GO WITH A LOW CHANCE OF RAIN BEGINNING IN SOUTHEAST GEORGIA
WEDNESDAY AFTERNOON AND THEN INCREASE POPS TO 30 TO 40 PERCENT
ACROSS GEORGIA AND THE SUWANNEE RIVER VALLEY OF NORTH FLORIDA
WEDNESDAY NIGHT AS THE FRONT PUSHES SOUTH. WILL FURTHER INCREASE
POPS UP TO 50 PERCENT ON THURSDAY AND SHOW A TREND FROM NORTH TO
SOUTH THROUGH THE DAY. MOST AREAS WILL ACTUALLY SEE FALLING
TEMPERATURES ON THURSDAY WITH HIGHS RANGING FROM THE LOW 60S NORTH
TO THE MID 70S SOUTH.
BEYOND THURSDAY...THE FORECAST BECOMES A LITTLE MORE UNCERTAIN BUT
THE LATEST MODEL RUNS HAVE TRENDED TOWARDS A WETTER SOLUTION
FRIDAY AND SATURDAY WITH A CONTINUATION OF CLOUDY AND COOLER
CONDITIONS. THE FLOW WILL QUICKLY TURN TO THE NORTHEAST THURSDAY
NIGHT AS STRONG HIGH PRESSURE MOVES TO THE MID-ATLANTIC SEABOARD.
THIS WILL KEEP THE FRONT FROM MOVING TOO FAR SOUTH WHICH IN TURN
WILL ACT TO KEEP DEEPER LAYER MOISTURE OVER AT LEAST THE SOUTH
HALF OF THE FORECAST AREA. AT THE SAME TIME...THE NORTHEAST SURGE
IS PROGGED TO BE STRONG ENOUGH TO RESULT IN SUFFICIENT MOISTURE
CONVERGENCE TO PRODUCE SOME RAIN SHOWERS...WITH THE HIGHEST COVERAGE
EXPECTED ALONG THE COAST. WILL HIGHLIGHT THIS POTENTIAL BY
INCREASING POPS IN THESE AREAS TO 20 TO 30 PERCENT ON FRIDAY AND
SATURDAY.
&&
.AVIATION...
FOG FORECAST IS A CHALLENGE THIS MORNING. SO FAR...FOG HAS BEEN
SLOW TO DEVELOP BUT CONDITIONS REMAIN FAVORABLE FOR A PERIOD OF
LIFR TO VLIFR CONDITIONS AROUND THE TIME OF SUNRISE THIS MORNING.
CONDITIONS WILL IMPROVE TO VFR BY MID MORNING.
&&
.MARINE...MAIN CONCERN IN THE SHORT TERM WILL BE SEA FOG IN THE
EARLY MORNING AND AFTN ALONG THE NEARSHORE ZONES GENERALLY N OF
MAYPORT AND FERNANDINA BEACH. THE FOG WILL LIKELY RETURN AGAIN EARLY
MONDAY MORNING. WINDS/SEAS WILL BE BELOW ADVY CRITERIA THROUGH EARLY
WEEK.
RIP CURRENTS: LOW RISK RIP CURRENTS TODAY-MONDAY.
&&
.PRELIMINARY POINT TEMPS/POPS...
AMG 80 57 80 54 / 10 10 10 10
SSI 70 57 73 57 / 0 10 10 0
JAX 80 56 80 55 / 0 10 10 0
SGJ 77 59 75 58 / 0 0 0 0
GNV 82 56 80 54 / 0 0 0 0
OCF 82 58 81 55 / 0 0 0 0
&&
.JAX WATCHES/WARNINGS/ADVISORIES...
FL...NONE.
GA...DENSE FOG ADVISORY UNTIL 10 AM EST THIS MORNING FOR BRANTLEY-
COASTAL CAMDEN-COASTAL GLYNN-INLAND CAMDEN-INLAND GLYNN-
WAYNE.
AM...DENSE FOG ADVISORY UNTIL 1 PM EST THIS AFTERNOON FOR ALTAMAHA
SOUND GA TO FERNANDINA BEACH FL OUT 20 NM.
&&
$$
SHASHY/SHULER/
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
412 PM CST SUN JAN 13 2013
.DISCUSSION...
246 PM CST
MAIN FORECAST CONCERN IS WITH MIXED WINTRY PRECIP OCCURRING ACROSS
EASTERN PARTS OF THE FORECAST AREA THIS AFTERNOON. ATTENTION THEN
SHIFTS TO SEASONABLY COLD BUT DRY WEATHER FOR MUCH OF THIS WEEK.
SOME INDICATIONS REMAIN THAT IT MAY EVENTUALLY TURN MUCH COLDER JUST
BEYOND THE END OF THE EXTENDED PERIOD.
NEAR TERM...REMAINDER OF THIS AFTERNOON/EARLY EVENING.
AREA OF MIXED WINTER PRECIP HAS SPREAD ACROSS THE FAR EASTERN PARTS
OF THE WFO LOT CWA THIS AFTERNOON. MID-LEVEL SHORT WAVE RESPONSIBLE
FOR THIS MESS IS CLEARLY IDENTIFIABLE IN GOES WATER VAPOR IMAGERY...
AND EXTRAPOLATION OF THIS FEATURE AS WELL AS WESTERN/TRAILING EDGE
OF RADAR DETECTABLE PRECIP INDICATES THAT THE MIXED PRECIP SHOULD
WIND DOWN FAIRLY QUICKLY IN THE 22-24Z (4-6 PM) TIMEFRAME. PATCHY
FLURRIES AND LIGHT FREEZING DRIZZLE ACROSS NORTHEAST IL SHOULD ALSO
END QUICKLY BY EVENING WITH LOSS OF FORCING BY EVENING. WARM
MID-LEVEL THERMAL PROFILE NOTED IN ILX 12Z SOUNDING DID INDEED
RESULT IN SOME SLEET/FREEZING RAIN ACROSS EASTERN AREAS THIS
AFTERNOON...THOUGH PRECIP WAS GENERALLY TRANSITIONING OVER TO LIGHT
SNOW AT 2 PM CST WITH SOME MODERATE SNOW AT TIMES AS INDICATED BY
VISIBILITY DOWN TO 3/4SM IN A FEW SPOTS A LITTLE EARLIER. AFTERNOON
VIS SATELLITE IMAGERY INDICATES CLOUDS CLEARING FROM THE WEST ACROSS
WESTERN IL...AND THIS TREND SHOULD CONTINUE THROUGH THE EVENING AS
THE UPPER TROUGH OVER THE MIDWEST LIFTS NORTHEAST...AND COLD/DRY LOW
LEVEL ADVECTION PERSISTS FROM THE WEST. WHILE IT WILL BE CHILLY
TONIGHT...HAVE GONE ABOVE MOS MINS FOR OVERNIGHT LOWS...AS MODELS
HAVE INITIALIZED SNOW COVER WHICH DID NOT ACTUALLY MATERIALIZE FROM
SATURDAY NIGHT. (WRF-NAM FOR INSTANCE HAS A 2-3 INCH STRIPE
INITIALIZED FROM BUREAU COUNTY TO MCHENRY COUNTY IN NORTHERN IL).
MEDIUM RANGE...MONDAY THROUGH THURSDAY...
SURFACE HIGH PRESSURE SPREADS ACROSS THE AREA ON MONDAY AS UPPER
TROUGH CURRENTLY ACROSS THE MISSISSIPPI VALLEY LIFTS NORTHEAST AND
AWAY FROM THE REGION. SPLIT UPPER FLOW FOCUSES ANY SIGNIFICANT
SENSIBLE WEATHER OVER THE SOUTHWESTERN CONUS WHERE A CLOSED UPPER
LOW DEVELOPS TONIGHT/MONDAY...AND ACROSS THE PACIFIC NORTHWEST WHERE
A STRONG UPPER JET STREAK MOVES IN OFF THE NORTH PACIFIC. THIS JET
EVENTUALLY LEADS TO A DEEPENING AREA OF SURFACE LOW PRESSURE IN THE
LEE OF THE CANADIAN ROCKIES WHICH MOVES EAST ACROSS ONTARIO THROUGH
EARLY WEDNESDAY. SURFACE HIGH PRESSURE RIDGE ACROSS THE MIDWEST
MONDAY/TUESDAY IS THUS DISPLACED SOUTHWARD AS PRESSURE FALLS DEVELOP
ACROSS THE UPPER MIDWEST AND NORTHERN LAKES IN ASSOCIATION WITH THE
CANADIAN LOW. DRY AND SEASONABLY COOL/COLD WEATHER WILL BE THE RULE
EARLY IN THE WEEK...MODERATING BACK TO SLIGHTLY ABOVE NORMAL TEMPS
IN THE 30S BY MID-WEEK AS WEST/SOUTHWEST FLOW INCREASES NORTH OF THE
RETREATING SURFACE RIDGE AND SOUTH OF THE ONTARIO LOW PRESSURE
SYSTEM. SURFACE COLD FRONT THEN TRAILS THE CANADIAN LOW ACROSS THE
CWA WEDNESDAY NIGHT...RESULTING IN COLDER TEMPS CLOSER TO NORMAL
(UPPER 20S) FOR THURSDAY. FRONT DOES NOT MAKE MUCH OF A SOUTHWARD
PUSH HOWEVER AND REALLY ONLY PROVIDES A GLANCING BRUSH OF COLDER AIR
AS THE MID/UPPER LEVEL FLOW BECOMES MORE WESTERLY. VARIOUS GUIDANCE
MAINTAIN VERY DRY MOISTURE PROFILES ACROSS THE MIDWEST THROUGH
MID-WEEK...RESULTING IN LITTLE/NO QPF EVEN WITH THE FROPA LATE
WEDNESDAY. THEREFORE IT APPEARS CHICAGO/S STREAK OF DAYS WITHOUT A 1
INCH SNOWFALL WILL CONTINUE THROUGH MID-JANUARY AT LEAST.
LONGER RANGE...FRIDAY-SUNDAY...
GUIDANCE REMAIN IN PRETTY GOOD AGREEMENT IN MAINTAINING
WEST-NORTHWEST FLOW ALOFT FRIDAY...BEFORE GRADUALLY AMPLIFYING LARGE
SCALE UPPER TROUGH OVER THE EASTERN HALF OF NORTH AMERICA THROUGH
THE WORK OF A COUPLE DEEP SHORT WAVE TROUGHS THROUGH THE WEEKEND.
COLDER TREND IN TEMPS BEGINS SUNDAY...THE LAST DAY OF THIS FORECAST
PACKAGE...THOUGH MODEL TRENDS CONTINUE TO SUGGEST A PLUNGE OF TRUE
BITTER COLD ARCTIC AIR MONDAY/TUESDAY OF THE FOLLOWING WEEK.
RATZER
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 22Z...
* PERIODIC MVFR CIGS LIKELY INTO EARLY EVENING WITH A FEW FLURRIES
IZZI
//DISCUSSION...UPDATED 18Z...
AS RAP OUTPUT CONTINUES TO DO A DECENT JOB IN HANDLING LOCATION
OF REFLECTIVITY HAVE FOLLOWED LATEST AVAILABLE VERSION /16Z/ AS
BASIS OF AFTERNOON AND EARLY EVENING FORECAST.
A SHORT WAVE HAS LIFTED FROM OVER FAR NORTHEAST TX AND SOUTHWEST
OK TO NORTHEASTERN AR AND SOUTHEASTERN MO DURING THE MORNING...
AND IS PROGGED TO MOVE NORTHEAST TO NORTHERN IL BY 00Z. HEAVIEST
PRECIPITATION WAS WELL TO THE SE THROUGH SW OF THE REGION...
CLOSER TO THE LOWER LEVEL BAROCLINIC ZONE. FURTHER NORTH...RADAR
ECHOES CONTINUE TO ADVANCE FROM CENTRAL IL TO THE FAR SOUTH TIP
OF LAKE MI AND NORTHWEST AND WEST CENTRAL IN AS THE SHORT WAVE
APPROACHES.
LOOP OF THE RAP COMPOSITE REFLECTIVITY FORECASTS SHOWS THE
NORTHWESTERN EDGE OF THE PRECIPITATION SHIELD MAKING NO FURTHER
NORTHWARD PROGRESS THIS AFTERNOON AND JUST GLANCING MDW BEFORE
MOVING OFF TO THE EAST BY EVENING AS SOUTHWEST WINDS VEER TO
WEST-SOUTHWEST AND WESTERLY IN THE LAYER FROM 1.5 TO 2.5 KM AGL
AND ADVECTING IN COLDER AND DRIER AIR FOLLOWING AN 850 HPA TROUGH
AXIS. THIS WILL ALSO RESULT IN SUBSIDENCE IN THE LOWER LAYERS AND
ANTICIPATE LOSS OF THE MVFR CEILINGS BY EARLY TO MID EVENING.
AS THE 700 HPA TROUGH MOVES ACROSS THE LOCAL AREA LATE THIS
EVENING SKIES SHOULD BECOME SKC TO SCT AS SUBSIDENCE EXPANDS UP
IN TO THE UPPER LEVELS.
TRS
//ORD AND MDW CONFIDENCE...UPDATED 22Z...
* MEDIUM CONFIDENCE IN CEILING TRENDS AND WIND TRENDS THIS EVENING.
* HIGH CONFIDENCE IN ALL OTHER ELEMENTS
IZZI
//OUTLOOK FOR ORD/MDW FOR 00Z TUESDAY-12Z SUNDAY...UPDATED 12Z...
MONDAY NIGHT THROUGH FRIDAY...PREDOMINANTLY VFR.
MTF
&&
.MARINE...
245 PM CST
AN ACTIVE PERIOD WILL CONTINUE OVER LAKE MICHIGAN THIS UPCOMING
WEEK...WITH GALES LIKELY FOR TUESDAY AFTERNOON THROUGH WEDNESDAY.
THIS AFTERNOON...LOW PRESSURE LIES OVER SOUTHERN QUEBEC WITH A
COLD FRONT EXTENDING SOUTHWEST INTO THE LOWER MISSISSIPPI
VALLEY...WITH HIGH PRESSURE SPRAWLING OVER THE NORTHERN AND CENTRAL
PLAINS. OVERNIGHT TONIGHT...THE LOW WILL LIFT NORTHEAST THROUGH
SOUTHERN QUEBEC WHILE THE COLD FRONT PUSHES THROUGH THE UPPER OHIO
RIVER VALLEY TO THE MID ATLANTIC REGION. BY TUESDAY...THE HIGH
WILL SPREAD ACROSS THE MIDDLE MISSISSIPPI VALLEY...TOWARD THE OHIO
VALLEY. MEANWHILE ANOTHER LOW WILL DROP SOUTHEAST INTO
SASKATCHEWAN AND DEEPEN AS IT MOVES ACROSS THE NORTHERN GREAT
LAKES REGION. THE COMBINATION OF NEARLY STATIONARY HIGH PRESSURE
OVER THE OHIO VALLEY...THE LOW DEEPENING AS IT SWINGS THROUGH THE
UPPER GREAT LAKES AND SOUTH CENTRAL CANADA AND AN APPROACHING
FRONTAL TROUGH ASSOCIATED WITH THE LOW WILL LEAD TO SOUTHWESTERLY
GALES DEVELOPING OVER THE NORTHERN PORTIONS OF THE LAKE BY TUESDAY
AFTERNOON...AND SPREADING TO THE SOUTHERN PORTIONS OF THE LAKE
THROUGH THE EVENING. SOUTHWEST GALES...TO 45 KT WILL PERSIST OVER
THE LAKE UNTIL THE COLD FRONT SWEEPS ACROSS THE LAKE LATE
WEDNESDAY AFTERNOON HIGH PRESSURE BUILDING ACROSS THE PLAINS
ALLOWS THE PRESSURE GRADIENT OVER THE LAKE TO RELAX ENOUGH FOR
WINDS TO DROP BELOW GALE FORCE.
KREIN
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...SMALL CRAFT ADVISORY...INDIANA NEARSHORE WATERS UNTIL 4 PM MONDAY.
GALE WATCH...LMZ261-LMZ362-LMZ364-LMZ366-LMZ563-LMZ565-LMZ567-
LMZ669-LMZ671-LMZ868-LMZ870-LMZ872...3 PM TUESDAY TO 3 PM
WEDNESDAY.
GALE WATCH...LMZ080-LMZ673-LMZ675-LMZ777-LMZ779-LMZ874-LMZ876-
LMZ878...9 PM TUESDAY TO 3 PM WEDNESDAY.
&&
$$
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
247 PM CST SUN JAN 13 2013
.DISCUSSION...
246 PM CST
MAIN FORECAST CONCERN IS WITH MIXED WINTRY PRECIP OCCURRING ACROSS
EASTERN PARTS OF THE FORECAST AREA THIS AFTERNOON. ATTENTION THEN
SHIFTS TO SEASONABLY COLD BUT DRY WEATHER FOR MUCH OF THIS WEEK.
SOME INDICATIONS REMAIN THAT IT MAY EVENTUALLY TURN MUCH COLDER JUST
BEYOND THE END OF THE EXTENDED PERIOD.
NEAR TERM...REMAINDER OF THIS AFTERNOON/EARLY EVENING.
AREA OF MIXED WINTER PRECIP HAS SPREAD ACROSS THE FAR EASTERN PARTS
OF THE WFO LOT CWA THIS AFTERNOON. MID-LEVEL SHORT WAVE RESPONSIBLE
FOR THIS MESS IS CLEARLY IDENTIFIABLE IN GOES WATER VAPOR IMAGERY...
AND EXTRAPOLATION OF THIS FEATURE AS WELL AS WESTERN/TRAILING EDGE
OF RADAR DETECTABLE PRECIP INDICATES THAT THE MIXED PRECIP SHOULD
WIND DOWN FAIRLY QUICKLY IN THE 22-24Z (4-6 PM) TIMEFRAME. PATCHY
FLURRIES AND LIGHT FREEZING DRIZZLE ACROSS NORTHEAST IL SHOULD ALSO
END QUICKLY BY EVENING WITH LOSS OF FORCING BY EVENING. WARM
MID-LEVEL THERMAL PROFILE NOTED IN ILX 12Z SOUNDING DID INDEED
RESULT IN SOME SLEET/FREEZING RAIN ACROSS EASTERN AREAS THIS
AFTERNOON...THOUGH PRECIP WAS GENERALLY TRANSITIONING OVER TO LIGHT
SNOW AT 2 PM CST WITH SOME MODERATE SNOW AT TIMES AS INDICATED BY
VISIBILITY DOWN TO 3/4SM IN A FEW SPOTS A LITTLE EARLIER. AFTERNOON
VIS SATELLITE IMAGERY INDICATES CLOUDS CLEARING FROM THE WEST ACROSS
WESTERN IL...AND THIS TREND SHOULD CONTINUE THROUGH THE EVENING AS
THE UPPER TROUGH OVER THE MIDWEST LIFTS NORTHEAST...AND COLD/DRY LOW
LEVEL ADVECTION PERSISTS FROM THE WEST. WHILE IT WILL BE CHILLY
TONIGHT...HAVE GONE ABOVE MOS MINS FOR OVERNIGHT LOWS...AS MODELS
HAVE INITIALIZED SNOW COVER WHICH DID NOT ACTUALLY MATERIALIZE FROM
SATURDAY NIGHT. (WRF-NAM FOR INSTANCE HAS A 2-3 INCH STRIPE
INITIALIZED FROM BUREAU COUNTY TO MCHENRY COUNTY IN NORTHERN IL).
MEDIUM RANGE...MONDAY THROUGH THURSDAY...
SURFACE HIGH PRESSURE SPREADS ACROSS THE AREA ON MONDAY AS UPPER
TROUGH CURRENTLY ACROSS THE MISSISSIPPI VALLEY LIFTS NORTHEAST AND
AWAY FROM THE REGION. SPLIT UPPER FLOW FOCUSES ANY SIGNIFICANT
SENSIBLE WEATHER OVER THE SOUTHWESTERN CONUS WHERE A CLOSED UPPER
LOW DEVELOPS TONIGHT/MONDAY...AND ACROSS THE PACIFIC NORTHWEST WHERE
A STRONG UPPER JET STREAK MOVES IN OFF THE NORTH PACIFIC. THIS JET
EVENTUALLY LEADS TO A DEEPENING AREA OF SURFACE LOW PRESSURE IN THE
LEE OF THE CANADIAN ROCKIES WHICH MOVES EAST ACROSS ONTARIO THROUGH
EARLY WEDNESDAY. SURFACE HIGH PRESSURE RIDGE ACROSS THE MIDWEST
MONDAY/TUESDAY IS THUS DISPLACED SOUTHWARD AS PRESSURE FALLS DEVELOP
ACROSS THE UPPER MIDWEST AND NORTHERN LAKES IN ASSOCIATION WITH THE
CANADIAN LOW. DRY AND SEASONABLY COOL/COLD WEATHER WILL BE THE RULE
EARLY IN THE WEEK...MODERATING BACK TO SLIGHTLY ABOVE NORMAL TEMPS
IN THE 30S BY MID-WEEK AS WEST/SOUTHWEST FLOW INCREASES NORTH OF THE
RETREATING SURFACE RIDGE AND SOUTH OF THE ONTARIO LOW PRESSURE
SYSTEM. SURFACE COLD FRONT THEN TRAILS THE CANADIAN LOW ACROSS THE
CWA WEDNESDAY NIGHT...RESULTING IN COLDER TEMPS CLOSER TO NORMAL
(UPPER 20S) FOR THURSDAY. FRONT DOES NOT MAKE MUCH OF A SOUTHWARD
PUSH HOWEVER AND REALLY ONLY PROVIDES A GLANCING BRUSH OF COLDER AIR
AS THE MID/UPPER LEVEL FLOW BECOMES MORE WESTERLY. VARIOUS GUIDANCE
MAINTAIN VERY DRY MOISTURE PROFILES ACROSS THE MIDWEST THROUGH
MID-WEEK...RESULTING IN LITTLE/NO QPF EVEN WITH THE FROPA LATE
WEDNESDAY. THEREFORE IT APPEARS CHICAGO/S STREAK OF DAYS WITHOUT A 1
INCH SNOWFALL WILL CONTINUE THROUGH MID-JANUARY AT LEAST.
LONGER RANGE...FRIDAY-SUNDAY...
GUIDANCE REMAIN IN PRETTY GOOD AGREEMENT IN MAINTAINING
WEST-NORTHWEST FLOW ALOFT FRIDAY...BEFORE GRADUALLY AMPLIFYING LARGE
SCALE UPPER TROUGH OVER THE EASTERN HALF OF NORTH AMERICA THROUGH
THE WORK OF A COUPLE DEEP SHORT WAVE TROUGHS THROUGH THE WEEKEND.
COLDER TREND IN TEMPS BEGINS SUNDAY...THE LAST DAY OF THIS FORECAST
PACKAGE...THOUGH MODEL TRENDS CONTINUE TO SUGGEST A PLUNGE OF TRUE
BITTER COLD ARCTIC AIR MONDAY/TUESDAY OF THE FOLLOWING WEEK.
RATZER
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 20Z...
* LOWER END MVFR CEILINGS IMPROVING TO UPPER END OF MVFR RANGE BY
LATE AFTERNOON...GOING VFR BY EARLY EVENING.
* LIGHT SNOW AT MDW ENDING MID AFTERNOON WITH MINIMAL IF ANY
ACCUMULATION.
* NNW WIND INCREASING SLIGHTLY LATE AFTERNOON AND THIS EVENING...
BECOMING MODESTLY GUSTY 16-18KT THIS EVENING.
TRS
//DISCUSSION...UPDATED 18Z...
AS RAP OUTPUT CONTINUES TO DO A DECENT JOB IN HANDLING LOCATION
OF REFLECTIVITY HAVE FOLLOWED LATEST AVAILABLE VERSION /16Z/ AS
BASIS OF AFTERNOON AND EARLY EVENING FORECAST.
A SHORT WAVE HAS LIFTED FROM OVER FAR NORTHEAST TX AND SOUTHWEST
OK TO NORTHEASTERN AR AND SOUTHEASTERN MO DURING THE MORNING...
AND IS PROGGED TO MOVE NORTHEAST TO NORTHERN IL BY 00Z. HEAVIEST
PRECIPITATION WAS WELL TO THE SE THROUGH SW OF THE REGION...
CLOSER TO THE LOWER LEVEL BAROCLINIC ZONE. FURTHER NORTH...RADAR
ECHOES CONTINUE TO ADVANCE FROM CENTRAL IL TO THE FAR SOUTH TIP
OF LAKE MI AND NORTHWEST AND WEST CENTRAL IN AS THE SHORT WAVE
APPROACHES.
LOOP OF THE RAP COMPOSITE REFLECTIVITY FORECASTS SHOWS THE
NORTHWESTERN EDGE OF THE PRECIPITATION SHIELD MAKING NO FURTHER
NORTHWARD PROGRESS THIS AFTERNOON AND JUST GLANCING MDW BEFORE
MOVING OFF TO THE EAST BY EVENING AS SOUTHWEST WINDS VEER TO
WEST-SOUTHWEST AND WESTERLY IN THE LAYER FROM 1.5 TO 2.5 KM AGL
AND ADVECTING IN COLDER AND DRIER AIR FOLLOWING AN 850 HPA TROUGH
AXIS. THIS WILL ALSO RESULT IN SUBSIDENCE IN THE LOWER LAYERS AND
ANTICIPATE LOSS OF THE MVFR CEILINGS BY EARLY TO MID EVENING.
AS THE 700 HPA TROUGH MOVES ACROSS THE LOCAL AREA LATE THIS
EVENING SKIES SHOULD BECOME SKC TO SCT AS SUBSIDENCE EXPANDS UP
IN TO THE UPPER LEVELS.
TRS
//ORD AND MDW CONFIDENCE...UPDATED 20Z...
* MEDIUM CONFIDENCE IN CEILING TRENDS.
* HIGH CONFIDENCE IN AREA OF -SN REMAINING JUST TO NORTHEAST
TROUGH SOUTHWEST OF ORD VICINITY.
* HIGH CONFIDENCE LIGHT SNOW ENDING AT MDW AROUND 22Z.
* HIGH CONFIDENCE IN WIND TRENDS.
TRS
//OUTLOOK FOR ORD/MDW FOR 00Z TUESDAY-12Z SUNDAY...UPDATED 12Z...
MONDAY NIGHT THROUGH FRIDAY...PREDOMINANTLY VFR.
MTF
&&
.MARINE...
245 PM CST
AN ACTIVE PERIOD WILL CONTINUE OVER LAKE MICHIGAN THIS UPCOMING
WEEK...WITH GALES LIKELY FOR TUESDAY AFTERNOON THROUGH WEDNESDAY.
THIS AFTERNOON...LOW PRESSURE LIES OVER SOUTHERN QUEBEC WITH A
COLD FRONT EXTENDING SOUTHWEST INTO THE LOWER MISSISSIPPI
VALLEY...WITH HIGH PRESSURE SPRAWLING OVER THE NORTHERN AND CENTRAL
PLAINS. OVERNIGHT TONIGHT...THE LOW WILL LIFT NORTHEAST THROUGH
SOUTHERN QUEBEC WHILE THE COLD FRONT PUSHES THROUGH THE UPPER OHIO
RIVER VALLEY TO THE MID ATLANTIC REGION. BY TUESDAY...THE HIGH
WILL SPREAD ACROSS THE MIDDLE MISSISSIPPI VALLEY...TOWARD THE OHIO
VALLEY. MEANWHILE ANOTHER LOW WILL DROP SOUTHEAST INTO
SASKATCHEWAN AND DEEPEN AS IT MOVES ACROSS THE NORTHERN GREAT
LAKES REGION. THE COMBINATION OF NEARLY STATIONARY HIGH PRESSURE
OVER THE OHIO VALLEY...THE LOW DEEPENING AS IT SWINGS THROUGH THE
UPPER GREAT LAKES AND SOUTH CENTRAL CANADA AND AN APPROACHING
FRONTAL TROUGH ASSOCIATED WITH THE LOW WILL LEAD TO SOUTHWESTERLY
GALES DEVELOPING OVER THE NORTHERN PORTIONS OF THE LAKE BY TUESDAY
AFTERNOON...AND SPREADING TO THE SOUTHERN PORTIONS OF THE LAKE
THROUGH THE EVENING. SOUTHWEST GALES...TO 45 KT WILL PERSIST OVER
THE LAKE UNTIL THE COLD FRONT SWEEPS ACROSS THE LAKE LATE
WEDNESDAY AFTERNOON HIGH PRESSURE BUILDING ACROSS THE PLAINS
ALLOWS THE PRESSURE GRADIENT OVER THE LAKE TO RELAX ENOUGH FOR
WINDS TO DROP BELOW GALE FORCE.
KREIN
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...SMALL CRAFT ADVISORY...INDIANA NEARSHORE WATERS UNTIL 4 PM MONDAY.
GALE WATCH...LMZ261-LMZ362-LMZ364-LMZ366-LMZ563-LMZ565-LMZ567-
LMZ669-LMZ671-LMZ868-LMZ870-LMZ872...3 PM TUESDAY TO 3 PM
WEDNESDAY.
GALE WATCH...LMZ080-LMZ673-LMZ675-LMZ777-LMZ779-LMZ874-LMZ876-
LMZ878...9 PM TUESDAY TO 3 PM WEDNESDAY.
&&
$$
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
242 PM CST SUN JAN 13 2013
.DISCUSSION...
1049 AM CST
FOR MORNING UPDATE...
ONLY MINOR CHANGES TO GOING FORECAST THIS MORNING.
FORECAST AREA REMAINS EAST OF LARGE SCALE UPPER TROUGH AXIS...
BENEATH SOUTHWEST-NORTHEAST ORIENTED UPPER JET AXIS AND LOW-MID
LEVEL BAROCLINIC ZONE WHICH STRETCHES FROM THE SOUTHERN PLAINS TO
THE GREAT LAKES REGION. SHORT WAVE TROUGH WHICH BROUGHT FREEZING
RAIN/SLEET TO THE AREA LAST NIGHT HAS LIFTED WELL TO THE NORTHEAST
OF THE AREA WITH ITS ASSOCIATED SURFACE LOW OVER WESTERN LAKE
ONTARIO AT MID-MORNING...WHILE ANOTHER JET STREAK AND LOW-AMPLITUDE
MID-LEVEL WAVE WAS NOTED UPSTREAM APPROACHING THE LOWER MISSOURI
VALLEY. THIS WAVE IS EXPECTED TO CONTINUE TO PROPAGATE NORTHEAST TO
THE GREAT LAKES THROUGH THIS EVENING...WITH WEAK SURFACE WAVE OVER
NORTHERN MISSISSIPPI RIPPLING NORTHEAST ALONG THE SURFACE FRONT INTO
THE UPPER OHIO VALLEY BY EARLY THIS EVENING.
12Z SOUNDINGS FROM LOCATIONS UPSTREAM INDICATE A LACK OF SOLID DEEP
MOISTURE AS BEST MOIST PLUME HAS NOW MOVED EAST OF OUR LOCAL AREA
PER WATER VAPOR IMAGERY...THOUGH A PERIOD OF MODERATE MID/UPPER
LEVEL FORCING IS DEPICTED BY VARIOUS MODELS WITH THE APPROACHING
WAVE WHICH WILL HELP MOISTEN AT LEAST PORTIONS OF THE COLUMN ACROSS
THE SOUTHEASTERN PARTS OF THE CWA THIS AFTERNOON. AREA OF INCREASING
RADAR RETURNS ACROSS SOUTHEAST MO AND SOUTHWESTERN IL ARE EXPECTED
TO SPREAD NORTHEAST ACROSS EAST CENTRAL IL AND NORTHWEST INDIANA
DURING THE MID-LATE AFTERNOON HOURS...WITH THE POTENTIAL FOR SOME
LIGHT SNOW AND PERHAPS EVEN A LITTLE LIGHT SLEET GIVEN LAYER OF ILX
12Z SOUNDING STILL AROUND 0 DEG C BETWEEN ABOUT 750-850 MB. 12Z
WRF-NAM TIME SECTIONS FOR GYY DEPICT SOME DECENT MID-LEVEL OMEGA
WITHIN GOOD DENDRITIC GROWTH ZONE FOR A TIME...AS WELL AS FAIRLY
STEEP LAPSE RATES AND EVEN A LITTLE ELEVATED CAPE ABOVE 600 MB...
THOUGH DRY LAYERS BELOW SUGGEST PRECIP MAY STRUGGLE TO GET TOO
IMPRESSIVE. STILL...POSSIBILITY EXISTS FOR SOME MINOR ACCUMS OF A
FEW TENTHS TO PERHAPS LESS THAN AN INCH ACROSS IL AREAS MAINLY EAST
OF I-57 AND EASTWARD INTO NORTHWEST INDIANA. FATHER WEST...ONLY A
FEW FLURRIES EXPECTED WITH DEEPER MOISTURE REALLY LACKING.
UPDATED NDFD GRIDS/ZFP ALREADY AVAILABLE.
RATZER
//PREV DISCUSSION...
340 AM CST
THE FORECAST CONCERNS ARE SOME LINGERING FZDZ POSSIBILITY THIS
MORNING AND THEN SNOW CHANCES THIS AFTERNOON ACROSS MAINLY
NORTHWEST IN. BEYOND THAT...FAIRLY QUIESCENT WEATHER AHEAD FOR
THIS WEEK.
EARLY MORNING WATER VAPOR DEPICTS THE MID-LEVEL SUBTROPICAL
MOISTURE PLUME SHIFTING VERY SLOWLY EAST FROM THE AREA IN ADVANCE
OF THE UPPER LEVEL LONG WAVE TROUGH ACROSS CENTRAL NORTH AMERICA.
THE LEAD SHORT WAVE IMPULSE RESPONSIBLE FOR LAST NIGHTS FREEZING
RAIN AND SLEET IN IL HAS LIFTED NORTHEAST INTO LOWER MI. THIS TOOK
THE MID-LEVEL MOISTURE SUPPORT FOR MOST OF THE CRYSTAL PRODUCTION
WITH IT...SO SNOW HAS CEASED. THE ASSOCIATED SURFACE LOW IS
LIFTING NORTHEAST ACROSS LAKE ERIE THIS MORNING WITH CONTINUED
COLD AIR ADVECTION OOZING IN ACROSS THE FORECAST AREA. RESIDUAL
MOISTURE AND SOME TRANSIENT ANALYZED OMEGA REMAINS IN THE LOWEST
SEVERAL THOUSAND FEET AND HAS PRODUCED PATCHES OF FZDZ. LOOKING AT
THE RAP AND OTHER HIGH RES SHORT TERM GUIDANCE...THE AREA ALONG
AND EAST OF I-57 WOULD BE SLIGHTLY MORE FAVORED THAN ELSEWHERE FOR
THESE PATCHES TO CONTINUE THROUGH MID-MORNING...BUT THEY SHOULD BE
LIGHT. WHILE THERE ARE INEVITABLY PLACES WITH ICY ROADS AFTER
LAST NIGHTS FREEZING PRECIP AND SLEET/SNOW...FURTHER ACCUMULATING
PRECIP THIS MORNING IS UNLIKELY IN THESE AREAS...SO HAVE LET THE
WINTER WEATHER ADVISORY GO.
ANOTHER SOMEWHAT SHEARED IMPULSE IS SEEN ACROSS OK/WESTERN AR
EARLY THIS MORNING WITHIN THE STRONG RIBBON OF UPPER LEVEL
SOUTHWESTERLIES AHEAD OF THE UPPER TROUGH. A 500MB SPEED MAX OF
AROUND 100 KT IN THAT AREA AS OBSERVED ON PROFILERS WILL MOVE
NORTHEAST THROUGH TODAY KEEPING THE WAVE FAIRLY INTACT AS IT
PROGRESSES ALONG A SHARPENING BAROCLINIC ZONE. PRONOUNCED
FRONTOGENESIS IS FORECAST BY BOTH THE NAM AND GFS AND MAKES SENSE
GIVEN THE THERMAL FIELDS PARALLEL ORIENTATION TO THE UPPER JET
AND THE WAVES PATH. LOOKING AT NAM CROSS SECTIONS...THERE IS
QUITE A BIT OF INSTABILITY FORECAST IN THE 700-550MB LAYER WHICH
IS JUST ABOVE AND WITHIN THE FORECAST THERMALLY INDUCED
CIRCULATION. WITH THE MOISTURE STILL ANOMALOUSLY HIGH IN THE MID-
LEVELS...WOULD EXPECT THE SUPPORT TO BE ENOUGH FOR SNOW TO
DEVELOP IN THE FAR EASTERN IL/WESTERN TO NORTHWEST INDIANA REGION
THIS AFTERNOON. SATELLITE TRENDS INDICATE A LITTLE FURTHER WEST
DEVELOPMENT FROM WHAT GUIDANCE SHOWS IS PLAUSIBLE GIVEN WHERE THE
WAVE IS AT...SO TRIED TO ACCOUNT FOR THAT TOO. THERE WILL BE A
SHARP CUTOFF ON THE WESTERN SIDE OF THIS SNOW AREA/BROAD
BAND...SO THE MOST FAVORED PART OF THE FORECAST AREA IS NORTHWEST
INDIANA. HAVE FORECAST SNOWFALL AMOUNTS AT ONE HALF TO A LITTLE
OVER AN INCH FROM FOWLER UP TO VALPARAISO...WITH SOME POTENTIAL
FOR LESSER ACCUMULATION BACK IN EASTERN IL.
MTF
LONG TERM...TONIGHT THROUGH NEXT SATURDAY...
HIGH PRESSURE SPREADS ACROSS THE CENTRAL PLAINS THIS AFTERNOON AND
REACHES INTO UPPER MISSISSIPPI RIVER VALLEY TONIGHT. DRIER AIR
ASSOCIATED WITH THE HIGH WILL HELP PUSH PRECIP EAST OF THE CWA
TONIGHT. SKIES WILL ALSO CLEAR ALLOWING TEMPS TO FALL INTO THE
TEENS TO SINGLE DIGITS. WENT A DEGREE OR TWO HIGHER THAN GUIDANCE
SINCE THE MODELS BELIEVE THERE IS A FRESH SNOW PACK ON THE GROUND.
HOWEVER FAIRLY CONFIDENT THAT IT WILL BE A CHILLY NIGHT SINCE WINDS
DIMINISH AND SKIES CLEAR. GUIDANCE KEEPS THE IMAGINARY SNOWPACK
THROUGH MID WEEK SO KEPT TEMPS SLIGHTLY ABOVE GUIDANCE THROUGH MID
WEEK.
THE HIGH PRESSURE BECOMES CENTERED OVER CENTRAL IL TUESDAY. ALOFT
THE DEEP TROUGH REMAINS OVER THE WESTERN HALF OF THE US THROUGH
TUESDAY NIGHT. IT THEN FINALLY MARCHES NORTH AND A CLOSED LOW FORMS
OVER TEXAS MID WEEK. THE DOWNSTREAM SIDE OF THE TROUGH WILL BE OVER
THE CWA THROUGH TUESDAY AS WELL LIMITING HOW MUCH OF THE ARCTIC AIR
INFILTRATES THE CWA. AS SUCH HIGH TEMPS THROUGH MID WEEK WILL BE
SLOWLY RISING TO ARND 30 DEGREES. WINDS TURN SOUTHWEST ON TUESDAY
WHICH WILL HELP TEMPS RISE TO AROUND FREEZING AND THEN AT OR
SLIGHTLY ABOVE FREEZING WEDNESDAY.
THE NORTHERN PART OF THE TROUGH PASSES OVERHEAD TUESDAY NIGHT WITH A
SECOND WAVE PASSING TO THE NORTH WEDNESDAY. A SURFACE LOW WILL MOVE
OVER SOUTHERN ONTARIO ON WEDNESDAY WITH PRECIP REMAINING TO OUR
NORTH. THE LOWS COLD FRONT SWINGS THROUGH THE CWA WEDNESDAY NIGHT
INTO THURSDAY MORNING WITH AN ABRUPT WIND SHIFT TO THE NORTHWEST AND
COOLER TEMPS. GUIDANCE SUGGESTS 850 MB TEMPS WILL FALL TO ARND -10C
WITH THE MUCH COLDER AIR REMAINING TO OUR NORTH. AS SUCH UPPER 20S
TO AROUND FREEZING TEMPS ARE EXPECTED THURSDAY. KEPT THE FRONT
PASSAGE DRY YET AGAIN. FORECAST SOUNDINGS INDICATE MOISTURE WILL BE
LIMITED WITH DRY CONDITIONS ABOVE 850MB. MAY SEE SOME PATCHY
DRIZZLE OR FREEZING DRIZZLE FORM ALONG THE COLD FRONT BUT NOT
EXPECTING ANYTHING WIDESPREAD OR MEASURABLE AT THIS POINT. THE
UPPER LEVEL VORTICITY STREAMER DOES CROSS SOUTHERN LAKE MICHIGAN SO
WILL HAVE TO MONITOR TO SEE IF IT COMES ANY FARTHER SOUTH AND
PROVIDES ANY ADDITIONAL SUPPORT.
HIGH PRESSURE PASSES THROUGH CENTRAL IL THURSDAY NIGHT INTO FRIDAY
WITH WINDS BECOMING SOUTHWEST BEHIND IT. THEN A WEAK LOW SYSTEM
APPROACHES FROM THE NORTHWEST LATE THIS WEEK. THE GFS FEATURES A
SURFACE LOW MOVING THROUGH SOUTHERN WI FRIDAY MORNING WHILE THE
ECMWF HAS A MUCH WEAKER WAVE OF ENERGY. GIVEN THE DISCONTINUITY DID
NOT INCLUDE PRECIP ON FRIDAY. A SECOND LOW IS PROGGED TO MOVE
THROUGH THE GREAT LAKES SATURDAY BUT DIFFERENCES IN TIMING AND
LOCATION ONCE AGAIN LED ME TO KEEP A DRY FORECAST GOING.
THE UPPER LEVEL JET REMAINS TO OUR NORTH WHICH WILL KEEP THE COLD
AIR TO OUR NORTH. MAX TEMPS FOR LATE THIS WEEK LOOK AROUND NORMAL
WITH ABOVE NORMAL LOW TEMPS.
JEE
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 20Z...
* LOWER END MVFR CEILINGS IMPROVING TO UPPER END OF MVFR RANGE BY
LATE AFTERNOON...GOING VFR BY EARLY EVENING.
* LIGHT SNOW AT MDW ENDING MID AFTERNOON WITH MINIMAL IF ANY
ACCUMULATION.
* NNW WIND INCREASING SLIGHTLY LATE AFTERNOON AND THIS EVENING...
BECOMING MODESTLY GUSTY 16-18KT THIS EVENING.
TRS
//DISCUSSION...UPDATED 18Z...
AS RAP OUTPUT CONTINUES TO DO A DECENT JOB IN HANDLING LOCATION
OF REFLECTIVITY HAVE FOLLOWED LATEST AVAILABLE VERSION /16Z/ AS
BASIS OF AFTERNOON AND EARLY EVENING FORECAST.
A SHORT WAVE HAS LIFTED FROM OVER FAR NORTHEAST TX AND SOUTHWEST
OK TO NORTHEASTERN AR AND SOUTHEASTERN MO DURING THE MORNING...
AND IS PROGGED TO MOVE NORTHEAST TO NORTHERN IL BY 00Z. HEAVIEST
PRECIPITATION WAS WELL TO THE SE THROUGH SW OF THE REGION...
CLOSER TO THE LOWER LEVEL BAROCLINIC ZONE. FURTHER NORTH...RADAR
ECHOES CONTINUE TO ADVANCE FROM CENTRAL IL TO THE FAR SOUTH TIP
OF LAKE MI AND NORTHWEST AND WEST CENTRAL IN AS THE SHORT WAVE
APPROACHES.
LOOP OF THE RAP COMPOSITE REFLECTIVITY FORECASTS SHOWS THE
NORTHWESTERN EDGE OF THE PRECIPITATION SHIELD MAKING NO FURTHER
NORTHWARD PROGRESS THIS AFTERNOON AND JUST GLANCING MDW BEFORE
MOVING OFF TO THE EAST BY EVENING AS SOUTHWEST WINDS VEER TO
WEST-SOUTHWEST AND WESTERLY IN THE LAYER FROM 1.5 TO 2.5 KM AGL
AND ADVECTING IN COLDER AND DRIER AIR FOLLOWING AN 850 HPA TROUGH
AXIS. THIS WILL ALSO RESULT IN SUBSIDENCE IN THE LOWER LAYERS AND
ANTICIPATE LOSS OF THE MVFR CEILINGS BY EARLY TO MID EVENING.
AS THE 700 HPA TROUGH MOVES ACROSS THE LOCAL AREA LATE THIS
EVENING SKIES SHOULD BECOME SKC TO SCT AS SUBSIDENCE EXPANDS UP
IN TO THE UPPER LEVELS.
TRS
//ORD AND MDW CONFIDENCE...UPDATED 20Z...
* MEDIUM CONFIDENCE IN CEILING TRENDS.
* HIGH CONFIDENCE IN AREA OF -SN REMAINING JUST TO NORTHEAST
TROUGH SOUTHWEST OF ORD VICINITY.
* HIGH CONFIDENCE LIGHT SNOW ENDING AT MDW AROUND 22Z.
* HIGH CONFIDENCE IN WIND TRENDS.
TRS
//OUTLOOK FOR ORD/MDW FOR 00Z TUESDAY-12Z SUNDAY...UPDATED 12Z...
MONDAY NIGHT THROUGH FRIDAY...PREDOMINANTLY VFR.
MTF
&&
.MARINE...
245 PM CST
AN ACTIVE PERIOD WILL CONTINUE OVER LAKE MICHIGAN THIS UPCOMING
WEEK...WITH GALES LIKELY FOR TUESDAY AFTERNOON THROUGH WEDNESDAY.
THIS AFTERNOON...LOW PRESSURE LIES OVER SOUTHERN QUEBEC WITH A
COLD FRONT EXTENDING SOUTHWEST INTO THE LOWER MISSISSIPPI
VALLEY...WITH HIGH PRESSURE SPRAWLING OVER THE NORTHERN AND CENTRAL
PLAINS. OVERNIGHT TONIGHT...THE LOW WILL LIFT NORTHEAST THROUGH
SOUTHERN QUEBEC WHILE THE COLD FRONT PUSHES THROUGH THE UPPER OHIO
RIVER VALLEY TO THE MID ATLANTIC REGION. BY TUESDAY...THE HIGH
WILL SPREAD ACROSS THE MIDDLE MISSISSIPPI VALLEY...TOWARD THE OHIO
VALLEY. MEANWHILE ANOTHER LOW WILL DROP SOUTHEAST INTO
SASKATCHEWAN AND DEEPEN AS IT MOVES ACROSS THE NORTHERN GREAT
LAKES REGION. THE COMBINATION OF NEARLY STATIONARY HIGH PRESSURE
OVER THE OHIO VALLEY...THE LOW DEEPENING AS IT SWINGS THROUGH THE
UPPER GREAT LAKES AND SOUTH CENTRAL CANADA AND AN APPROACHING
FRONTAL TROUGH ASSOCIATED WITH THE LOW WILL LEAD TO SOUTHWESTERLY
GALES DEVELOPING OVER THE NORTHERN PORTIONS OF THE LAKE BY TUESDAY
AFTERNOON...AND SPREADING TO THE SOUTHERN PORTIONS OF THE LAKE
THROUGH THE EVENING. SOUTHWEST GALES...TO 45 KT WILL PERSIST OVER
THE LAKE UNTIL THE COLD FRONT SWEEPS ACROSS THE LAKE LATE
WEDNESDAY AFTERNOON HIGH PRESSURE BUILDING ACROSS THE PLAINS
ALLOWS THE PRESSURE GRADIENT OVER THE LAKE TO RELAX ENOUGH FOR
WINDS TO DROP BELOW GALE FORCE.
KREIN
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...SMALL CRAFT ADVISORY...INDIANA NEARSHORE WATERS UNTIL 4 PM MONDAY.
GALE WATCH...LMZ261-LMZ362-LMZ364-LMZ366-LMZ563-LMZ565-LMZ567-
LMZ669-LMZ671-LMZ868-LMZ870-LMZ872...3 PM TUESDAY TO 3 PM
WEDNESDAY.
GALE WATCH...LMZ080-LMZ673-LMZ675-LMZ777-LMZ779-LMZ874-LMZ876-
LMZ878...9 PM TUESDAY TO 3 PM WEDNESDAY.
&&
$$
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
158 PM CST SUN JAN 13 2013
.DISCUSSION...
1049 AM CST
FOR MORNING UPDATE...
ONLY MINOR CHANGES TO GOING FORECAST THIS MORNING.
FORECAST AREA REMAINS EAST OF LARGE SCALE UPPER TROUGH AXIS...
BENEATH SOUTHWEST-NORTHEAST ORIENTED UPPER JET AXIS AND LOW-MID
LEVEL BAROCLINIC ZONE WHICH STRETCHES FROM THE SOUTHERN PLAINS TO
THE GREAT LAKES REGION. SHORT WAVE TROUGH WHICH BROUGHT FREEZING
RAIN/SLEET TO THE AREA LAST NIGHT HAS LIFTED WELL TO THE NORTHEAST
OF THE AREA WITH ITS ASSOCIATED SURFACE LOW OVER WESTERN LAKE
ONTARIO AT MID-MORNING...WHILE ANOTHER JET STREAK AND LOW-AMPLITUDE
MID-LEVEL WAVE WAS NOTED UPSTREAM APPROACHING THE LOWER MISSOURI
VALLEY. THIS WAVE IS EXPECTED TO CONTINUE TO PROPAGATE NORTHEAST TO
THE GREAT LAKES THROUGH THIS EVENING...WITH WEAK SURFACE WAVE OVER
NORTHERN MISSISSIPPI RIPPLING NORTHEAST ALONG THE SURFACE FRONT INTO
THE UPPER OHIO VALLEY BY EARLY THIS EVENING.
12Z SOUNDINGS FROM LOCATIONS UPSTREAM INDICATE A LACK OF SOLID DEEP
MOISTURE AS BEST MOIST PLUME HAS NOW MOVED EAST OF OUR LOCAL AREA
PER WATER VAPOR IMAGERY...THOUGH A PERIOD OF MODERATE MID/UPPER
LEVEL FORCING IS DEPICTED BY VARIOUS MODELS WITH THE APPROACHING
WAVE WHICH WILL HELP MOISTEN AT LEAST PORTIONS OF THE COLUMN ACROSS
THE SOUTHEASTERN PARTS OF THE CWA THIS AFTERNOON. AREA OF INCREASING
RADAR RETURNS ACROSS SOUTHEAST MO AND SOUTHWESTERN IL ARE EXPECTED
TO SPREAD NORTHEAST ACROSS EAST CENTRAL IL AND NORTHWEST INDIANA
DURING THE MID-LATE AFTERNOON HOURS...WITH THE POTENTIAL FOR SOME
LIGHT SNOW AND PERHAPS EVEN A LITTLE LIGHT SLEET GIVEN LAYER OF ILX
12Z SOUNDING STILL AROUND 0 DEG C BETWEEN ABOUT 750-850 MB. 12Z
WRF-NAM TIME SECTIONS FOR GYY DEPICT SOME DECENT MID-LEVEL OMEGA
WITHIN GOOD DENDRITIC GROWTH ZONE FOR A TIME...AS WELL AS FAIRLY
STEEP LAPSE RATES AND EVEN A LITTLE ELEVATED CAPE ABOVE 600 MB...
THOUGH DRY LAYERS BELOW SUGGEST PRECIP MAY STRUGGLE TO GET TOO
IMPRESSIVE. STILL...POSSIBILITY EXISTS FOR SOME MINOR ACCUMS OF A
FEW TENTHS TO PERHAPS LESS THAN AN INCH ACROSS IL AREAS MAINLY EAST
OF I-57 AND EASTWARD INTO NORTHWEST INDIANA. FATHER WEST...ONLY A
FEW FLURRIES EXPECTED WITH DEEPER MOISTURE REALLY LACKING.
UPDATED NDFD GRIDS/ZFP ALREADY AVAILABLE.
RATZER
//PREV DISCUSSION...
340 AM CST
THE FORECAST CONCERNS ARE SOME LINGERING FZDZ POSSIBILITY THIS
MORNING AND THEN SNOW CHANCES THIS AFTERNOON ACROSS MAINLY
NORTHWEST IN. BEYOND THAT...FAIRLY QUIESCENT WEATHER AHEAD FOR
THIS WEEK.
EARLY MORNING WATER VAPOR DEPICTS THE MID-LEVEL SUBTROPICAL
MOISTURE PLUME SHIFTING VERY SLOWLY EAST FROM THE AREA IN ADVANCE
OF THE UPPER LEVEL LONG WAVE TROUGH ACROSS CENTRAL NORTH AMERICA.
THE LEAD SHORT WAVE IMPULSE RESPONSIBLE FOR LAST NIGHTS FREEZING
RAIN AND SLEET IN IL HAS LIFTED NORTHEAST INTO LOWER MI. THIS TOOK
THE MID-LEVEL MOISTURE SUPPORT FOR MOST OF THE CRYSTAL PRODUCTION
WITH IT...SO SNOW HAS CEASED. THE ASSOCIATED SURFACE LOW IS
LIFTING NORTHEAST ACROSS LAKE ERIE THIS MORNING WITH CONTINUED
COLD AIR ADVECTION OOZING IN ACROSS THE FORECAST AREA. RESIDUAL
MOISTURE AND SOME TRANSIENT ANALYZED OMEGA REMAINS IN THE LOWEST
SEVERAL THOUSAND FEET AND HAS PRODUCED PATCHES OF FZDZ. LOOKING AT
THE RAP AND OTHER HIGH RES SHORT TERM GUIDANCE...THE AREA ALONG
AND EAST OF I-57 WOULD BE SLIGHTLY MORE FAVORED THAN ELSEWHERE FOR
THESE PATCHES TO CONTINUE THROUGH MID-MORNING...BUT THEY SHOULD BE
LIGHT. WHILE THERE ARE INEVITABLY PLACES WITH ICY ROADS AFTER
LAST NIGHTS FREEZING PRECIP AND SLEET/SNOW...FURTHER ACCUMULATING
PRECIP THIS MORNING IS UNLIKELY IN THESE AREAS...SO HAVE LET THE
WINTER WEATHER ADVISORY GO.
ANOTHER SOMEWHAT SHEARED IMPULSE IS SEEN ACROSS OK/WESTERN AR
EARLY THIS MORNING WITHIN THE STRONG RIBBON OF UPPER LEVEL
SOUTHWESTERLIES AHEAD OF THE UPPER TROUGH. A 500MB SPEED MAX OF
AROUND 100 KT IN THAT AREA AS OBSERVED ON PROFILERS WILL MOVE
NORTHEAST THROUGH TODAY KEEPING THE WAVE FAIRLY INTACT AS IT
PROGRESSES ALONG A SHARPENING BAROCLINIC ZONE. PRONOUNCED
FRONTOGENESIS IS FORECAST BY BOTH THE NAM AND GFS AND MAKES SENSE
GIVEN THE THERMAL FIELDS PARALLEL ORIENTATION TO THE UPPER JET
AND THE WAVES PATH. LOOKING AT NAM CROSS SECTIONS...THERE IS
QUITE A BIT OF INSTABILITY FORECAST IN THE 700-550MB LAYER WHICH
IS JUST ABOVE AND WITHIN THE FORECAST THERMALLY INDUCED
CIRCULATION. WITH THE MOISTURE STILL ANOMALOUSLY HIGH IN THE MID-
LEVELS...WOULD EXPECT THE SUPPORT TO BE ENOUGH FOR SNOW TO
DEVELOP IN THE FAR EASTERN IL/WESTERN TO NORTHWEST INDIANA REGION
THIS AFTERNOON. SATELLITE TRENDS INDICATE A LITTLE FURTHER WEST
DEVELOPMENT FROM WHAT GUIDANCE SHOWS IS PLAUSIBLE GIVEN WHERE THE
WAVE IS AT...SO TRIED TO ACCOUNT FOR THAT TOO. THERE WILL BE A
SHARP CUTOFF ON THE WESTERN SIDE OF THIS SNOW AREA/BROAD
BAND...SO THE MOST FAVORED PART OF THE FORECAST AREA IS NORTHWEST
INDIANA. HAVE FORECAST SNOWFALL AMOUNTS AT ONE HALF TO A LITTLE
OVER AN INCH FROM FOWLER UP TO VALPARAISO...WITH SOME POTENTIAL
FOR LESSER ACCUMULATION BACK IN EASTERN IL.
MTF
LONG TERM...TONIGHT THROUGH NEXT SATURDAY...
HIGH PRESSURE SPREADS ACROSS THE CENTRAL PLAINS THIS AFTERNOON AND
REACHES INTO UPPER MISSISSIPPI RIVER VALLEY TONIGHT. DRIER AIR
ASSOCIATED WITH THE HIGH WILL HELP PUSH PRECIP EAST OF THE CWA
TONIGHT. SKIES WILL ALSO CLEAR ALLOWING TEMPS TO FALL INTO THE
TEENS TO SINGLE DIGITS. WENT A DEGREE OR TWO HIGHER THAN GUIDANCE
SINCE THE MODELS BELIEVE THERE IS A FRESH SNOW PACK ON THE GROUND.
HOWEVER FAIRLY CONFIDENT THAT IT WILL BE A CHILLY NIGHT SINCE WINDS
DIMINISH AND SKIES CLEAR. GUIDANCE KEEPS THE IMAGINARY SNOWPACK
THROUGH MID WEEK SO KEPT TEMPS SLIGHTLY ABOVE GUIDANCE THROUGH MID
WEEK.
THE HIGH PRESSURE BECOMES CENTERED OVER CENTRAL IL TUESDAY. ALOFT
THE DEEP TROUGH REMAINS OVER THE WESTERN HALF OF THE US THROUGH
TUESDAY NIGHT. IT THEN FINALLY MARCHES NORTH AND A CLOSED LOW FORMS
OVER TEXAS MID WEEK. THE DOWNSTREAM SIDE OF THE TROUGH WILL BE OVER
THE CWA THROUGH TUESDAY AS WELL LIMITING HOW MUCH OF THE ARCTIC AIR
INFILTRATES THE CWA. AS SUCH HIGH TEMPS THROUGH MID WEEK WILL BE
SLOWLY RISING TO ARND 30 DEGREES. WINDS TURN SOUTHWEST ON TUESDAY
WHICH WILL HELP TEMPS RISE TO AROUND FREEZING AND THEN AT OR
SLIGHTLY ABOVE FREEZING WEDNESDAY.
THE NORTHERN PART OF THE TROUGH PASSES OVERHEAD TUESDAY NIGHT WITH A
SECOND WAVE PASSING TO THE NORTH WEDNESDAY. A SURFACE LOW WILL MOVE
OVER SOUTHERN ONTARIO ON WEDNESDAY WITH PRECIP REMAINING TO OUR
NORTH. THE LOWS COLD FRONT SWINGS THROUGH THE CWA WEDNESDAY NIGHT
INTO THURSDAY MORNING WITH AN ABRUPT WIND SHIFT TO THE NORTHWEST AND
COOLER TEMPS. GUIDANCE SUGGESTS 850 MB TEMPS WILL FALL TO ARND -10C
WITH THE MUCH COLDER AIR REMAINING TO OUR NORTH. AS SUCH UPPER 20S
TO AROUND FREEZING TEMPS ARE EXPECTED THURSDAY. KEPT THE FRONT
PASSAGE DRY YET AGAIN. FORECAST SOUNDINGS INDICATE MOISTURE WILL BE
LIMITED WITH DRY CONDITIONS ABOVE 850MB. MAY SEE SOME PATCHY
DRIZZLE OR FREEZING DRIZZLE FORM ALONG THE COLD FRONT BUT NOT
EXPECTING ANYTHING WIDESPREAD OR MEASURABLE AT THIS POINT. THE
UPPER LEVEL VORTICITY STREAMER DOES CROSS SOUTHERN LAKE MICHIGAN SO
WILL HAVE TO MONITOR TO SEE IF IT COMES ANY FARTHER SOUTH AND
PROVIDES ANY ADDITIONAL SUPPORT.
HIGH PRESSURE PASSES THROUGH CENTRAL IL THURSDAY NIGHT INTO FRIDAY
WITH WINDS BECOMING SOUTHWEST BEHIND IT. THEN A WEAK LOW SYSTEM
APPROACHES FROM THE NORTHWEST LATE THIS WEEK. THE GFS FEATURES A
SURFACE LOW MOVING THROUGH SOUTHERN WI FRIDAY MORNING WHILE THE
ECMWF HAS A MUCH WEAKER WAVE OF ENERGY. GIVEN THE DISCONTINUITY DID
NOT INCLUDE PRECIP ON FRIDAY. A SECOND LOW IS PROGGED TO MOVE
THROUGH THE GREAT LAKES SATURDAY BUT DIFFERENCES IN TIMING AND
LOCATION ONCE AGAIN LED ME TO KEEP A DRY FORECAST GOING.
THE UPPER LEVEL JET REMAINS TO OUR NORTH WHICH WILL KEEP THE COLD
AIR TO OUR NORTH. MAX TEMPS FOR LATE THIS WEEK LOOK AROUND NORMAL
WITH ABOVE NORMAL LOW TEMPS.
JEE
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 20Z...
* LOWER END MVFR CEILINGS IMPROVING TO UPPER END OF MVFR RANGE BY
LATE AFTERNOON...GOING VFR BY EARLY EVENING.
* LIGHT SNOW AT MDW ENDING MID AFTERNOON WITH MINIMAL IF ANY
ACCUMULATION.
* NNW WIND INCREASING SLIGHTLY LATE AFTERNOON AND THIS EVENING...
BECOMING MODESTLY GUSTY 16-18KT THIS EVENING.
TRS
//DISCUSSION...UPDATED 18Z...
AS RAP OUTPUT CONTINUES TO DO A DECENT JOB IN HANDLING LOCATION
OF REFLECTIVITY HAVE FOLLOWED LATEST AVAILABLE VERSION /16Z/ AS
BASIS OF AFTERNOON AND EARLY EVENING FORECAST.
A SHORT WAVE HAS LIFTED FROM OVER FAR NORTHEAST TX AND SOUTHWEST
OK TO NORTHEASTERN AR AND SOUTHEASTERN MO DURING THE MORNING...
AND IS PROGGED TO MOVE NORTHEAST TO NORTHERN IL BY 00Z. HEAVIEST
PRECIPITATION WAS WELL TO THE SE THROUGH SW OF THE REGION...
CLOSER TO THE LOWER LEVEL BAROCLINIC ZONE. FURTHER NORTH...RADAR
ECHOES CONTINUE TO ADVANCE FROM CENTRAL IL TO THE FAR SOUTH TIP
OF LAKE MI AND NORTHWEST AND WEST CENTRAL IN AS THE SHORT WAVE
APPROACHES.
LOOP OF THE RAP COMPOSITE REFLECTIVITY FORECASTS SHOWS THE
NORTHWESTERN EDGE OF THE PRECIPITATION SHIELD MAKING NO FURTHER
NORTHWARD PROGRESS THIS AFTERNOON AND JUST GLANCING MDW BEFORE
MOVING OFF TO THE EAST BY EVENING AS SOUTHWEST WINDS VEER TO
WEST-SOUTHWEST AND WESTERLY IN THE LAYER FROM 1.5 TO 2.5 KM AGL
AND ADVECTING IN COLDER AND DRIER AIR FOLLOWING AN 850 HPA TROUGH
AXIS. THIS WILL ALSO RESULT IN SUBSIDENCE IN THE LOWER LAYERS AND
ANTICIPATE LOSS OF THE MVFR CEILINGS BY EARLY TO MID EVENING.
AS THE 700 HPA TROUGH MOVES ACROSS THE LOCAL AREA LATE THIS
EVENING SKIES SHOULD BECOME SKC TO SCT AS SUBSIDENCE EXPANDS UP
IN TO THE UPPER LEVELS.
TRS
//ORD AND MDW CONFIDENCE...UPDATED 20Z...
* MEDIUM CONFIDENCE IN CEILING TRENDS.
* HIGH CONFIDENCE IN AREA OF -SN REMAINING JUST TO NORTHEAST
TROUGH SOUTHWEST OF ORD VICINITY.
* HIGH CONFIDENCE LIGHT SNOW ENDING AT MDW AROUND 22Z.
* HIGH CONFIDENCE IN WIND TRENDS.
TRS
//OUTLOOK FOR ORD/MDW FOR 00Z TUESDAY-12Z SUNDAY...UPDATED 12Z...
MONDAY NIGHT THROUGH FRIDAY...PREDOMINANTLY VFR.
MTF
&&
.MARINE...
227 AM CST
AN ACTIVE PERIOD WILL CONTINUE OVER LAKE MICHIGAN THIS UPCOMING
WEEK...WITH GALES LOOKING INCREASINGLY LIKELY FOR TUESDAY NIGHT AND
WEDNESDAY. THIS MORNING...LOW PRESSURE LIES OVER EAST CENTRAL
INDIANA WHILE A BROAD AREA OF HIGH PRESSURE SPANS THE NORTHERN
PLAINS. THIS LEAVES SOUTHERN PORTIONS OF LAKE MICHIGAN IN A MODEST
NORTHERLY GRADIENT...WHICH SHOULD DIMINISH GRADUALLY TODAY AND
TOMORROW AS HIGH PRESSURE GRADUALLY EXPANDS EASTWARD INFLUENCING
THE WESTERN GREAT LAKES REGION. THIS WILL LEAD TO A DOWNWARD TREND
IN WIND SPEEDS AS WIND DIRECTION TRENDS TO MORE NORTHWEST THEN
WESTERLY. WINDS WILL BEGIN TO TURN SOUTHWESTERLY AND INCREASE
AGAIN ON TUESDAY AS LOW PRESSURE QUICKLY MOVES EAST ACROSS THE
CANADIAN PRAIRIES...AND INTO THE NORTHERN GREAT LAKES REGION
TUESDAY NIGHT. NAM/GFS GUIDANCE IS IN DECENT AGREEMENT ON A MORE
SOUTHERLY AND DEEPER TRACK OF THE LOW AS COMPARED TO THE MORE
OPEN/NORTHERLY ECMWF. LIKEWISE...NAM/GFS GUIDANCE BOTH SHOWING
STRONG GALES PARTICULARLY ACROSS THE NORTHERN HALF OF THE LAKE
TUESDAY NIGHT INTO WEDNESDAY WHILE THE ECMWF HINTS TOWARDS AT
LEAST LOWER END GALES FOR THIS PERIOD. NORTHWEST/WEST WINDS WILL
REMAIN ELEVATED THROUGH PORTIONS OF THE DAY THURSDAY...BEFORE
FINALLY DIMINISHING AS BROAD AREA OF HIGH PRESSURE BUILDS ACROSS
THE MISSISSIPPI VALLEY WITH RIDGING EXTENDING NORTH INTO THE
WESTERN GREAT LAKES. BMD
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...SMALL CRAFT ADVISORY...INDIANA NEARSHORE WATERS UNTIL 11 AM MONDAY.
&&
$$
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
120 PM CST SUN JAN 13 2013
.DISCUSSION...
1049 AM CST
FOR MORNING UPDATE...
ONLY MINOR CHANGES TO GOING FORECAST THIS MORNING.
FORECAST AREA REMAINS EAST OF LARGE SCALE UPPER TROUGH AXIS...
BENEATH SOUTHWEST-NORTHEAST ORIENTED UPPER JET AXIS AND LOW-MID
LEVEL BAROCLINIC ZONE WHICH STRETCHES FROM THE SOUTHERN PLAINS TO
THE GREAT LAKES REGION. SHORT WAVE TROUGH WHICH BROUGHT FREEZING
RAIN/SLEET TO THE AREA LAST NIGHT HAS LIFTED WELL TO THE NORTHEAST
OF THE AREA WITH ITS ASSOCIATED SURFACE LOW OVER WESTERN LAKE
ONTARIO AT MID-MORNING...WHILE ANOTHER JET STREAK AND LOW-AMPLITUDE
MID-LEVEL WAVE WAS NOTED UPSTREAM APPROACHING THE LOWER MISSOURI
VALLEY. THIS WAVE IS EXPECTED TO CONTINUE TO PROPAGATE NORTHEAST TO
THE GREAT LAKES THROUGH THIS EVENING...WITH WEAK SURFACE WAVE OVER
NORTHERN MISSISSIPPI RIPPLING NORTHEAST ALONG THE SURFACE FRONT INTO
THE UPPER OHIO VALLEY BY EARLY THIS EVENING.
12Z SOUNDINGS FROM LOCATIONS UPSTREAM INDICATE A LACK OF SOLID DEEP
MOISTURE AS BEST MOIST PLUME HAS NOW MOVED EAST OF OUR LOCAL AREA
PER WATER VAPOR IMAGERY...THOUGH A PERIOD OF MODERATE MID/UPPER
LEVEL FORCING IS DEPICTED BY VARIOUS MODELS WITH THE APPROACHING
WAVE WHICH WILL HELP MOISTEN AT LEAST PORTIONS OF THE COLUMN ACROSS
THE SOUTHEASTERN PARTS OF THE CWA THIS AFTERNOON. AREA OF INCREASING
RADAR RETURNS ACROSS SOUTHEAST MO AND SOUTHWESTERN IL ARE EXPECTED
TO SPREAD NORTHEAST ACROSS EAST CENTRAL IL AND NORTHWEST INDIANA
DURING THE MID-LATE AFTERNOON HOURS...WITH THE POTENTIAL FOR SOME
LIGHT SNOW AND PERHAPS EVEN A LITTLE LIGHT SLEET GIVEN LAYER OF ILX
12Z SOUNDING STILL AROUND 0 DEG C BETWEEN ABOUT 750-850 MB. 12Z
WRF-NAM TIME SECTIONS FOR GYY DEPICT SOME DECENT MID-LEVEL OMEGA
WITHIN GOOD DENDRITIC GROWTH ZONE FOR A TIME...AS WELL AS FAIRLY
STEEP LAPSE RATES AND EVEN A LITTLE ELEVATED CAPE ABOVE 600 MB...
THOUGH DRY LAYERS BELOW SUGGEST PRECIP MAY STRUGGLE TO GET TOO
IMPRESSIVE. STILL...POSSIBILITY EXISTS FOR SOME MINOR ACCUMS OF A
FEW TENTHS TO PERHAPS LESS THAN AN INCH ACROSS IL AREAS MAINLY EAST
OF I-57 AND EASTWARD INTO NORTHWEST INDIANA. FATHER WEST...ONLY A
FEW FLURRIES EXPECTED WITH DEEPER MOISTURE REALLY LACKING.
UPDATED NDFD GRIDS/ZFP ALREADY AVAILABLE.
RATZER
//PREV DISCUSSION...
340 AM CST
THE FORECAST CONCERNS ARE SOME LINGERING FZDZ POSSIBILITY THIS
MORNING AND THEN SNOW CHANCES THIS AFTERNOON ACROSS MAINLY
NORTHWEST IN. BEYOND THAT...FAIRLY QUIESCENT WEATHER AHEAD FOR
THIS WEEK.
EARLY MORNING WATER VAPOR DEPICTS THE MID-LEVEL SUBTROPICAL
MOISTURE PLUME SHIFTING VERY SLOWLY EAST FROM THE AREA IN ADVANCE
OF THE UPPER LEVEL LONG WAVE TROUGH ACROSS CENTRAL NORTH AMERICA.
THE LEAD SHORT WAVE IMPULSE RESPONSIBLE FOR LAST NIGHTS FREEZING
RAIN AND SLEET IN IL HAS LIFTED NORTHEAST INTO LOWER MI. THIS TOOK
THE MID-LEVEL MOISTURE SUPPORT FOR MOST OF THE CRYSTAL PRODUCTION
WITH IT...SO SNOW HAS CEASED. THE ASSOCIATED SURFACE LOW IS
LIFTING NORTHEAST ACROSS LAKE ERIE THIS MORNING WITH CONTINUED
COLD AIR ADVECTION OOZING IN ACROSS THE FORECAST AREA. RESIDUAL
MOISTURE AND SOME TRANSIENT ANALYZED OMEGA REMAINS IN THE LOWEST
SEVERAL THOUSAND FEET AND HAS PRODUCED PATCHES OF FZDZ. LOOKING AT
THE RAP AND OTHER HIGH RES SHORT TERM GUIDANCE...THE AREA ALONG
AND EAST OF I-57 WOULD BE SLIGHTLY MORE FAVORED THAN ELSEWHERE FOR
THESE PATCHES TO CONTINUE THROUGH MID-MORNING...BUT THEY SHOULD BE
LIGHT. WHILE THERE ARE INEVITABLY PLACES WITH ICY ROADS AFTER
LAST NIGHTS FREEZING PRECIP AND SLEET/SNOW...FURTHER ACCUMULATING
PRECIP THIS MORNING IS UNLIKELY IN THESE AREAS...SO HAVE LET THE
WINTER WEATHER ADVISORY GO.
ANOTHER SOMEWHAT SHEARED IMPULSE IS SEEN ACROSS OK/WESTERN AR
EARLY THIS MORNING WITHIN THE STRONG RIBBON OF UPPER LEVEL
SOUTHWESTERLIES AHEAD OF THE UPPER TROUGH. A 500MB SPEED MAX OF
AROUND 100 KT IN THAT AREA AS OBSERVED ON PROFILERS WILL MOVE
NORTHEAST THROUGH TODAY KEEPING THE WAVE FAIRLY INTACT AS IT
PROGRESSES ALONG A SHARPENING BAROCLINIC ZONE. PRONOUNCED
FRONTOGENESIS IS FORECAST BY BOTH THE NAM AND GFS AND MAKES SENSE
GIVEN THE THERMAL FIELDS PARALLEL ORIENTATION TO THE UPPER JET
AND THE WAVES PATH. LOOKING AT NAM CROSS SECTIONS...THERE IS
QUITE A BIT OF INSTABILITY FORECAST IN THE 700-550MB LAYER WHICH
IS JUST ABOVE AND WITHIN THE FORECAST THERMALLY INDUCED
CIRCULATION. WITH THE MOISTURE STILL ANOMALOUSLY HIGH IN THE MID-
LEVELS...WOULD EXPECT THE SUPPORT TO BE ENOUGH FOR SNOW TO
DEVELOP IN THE FAR EASTERN IL/WESTERN TO NORTHWEST INDIANA REGION
THIS AFTERNOON. SATELLITE TRENDS INDICATE A LITTLE FURTHER WEST
DEVELOPMENT FROM WHAT GUIDANCE SHOWS IS PLAUSIBLE GIVEN WHERE THE
WAVE IS AT...SO TRIED TO ACCOUNT FOR THAT TOO. THERE WILL BE A
SHARP CUTOFF ON THE WESTERN SIDE OF THIS SNOW AREA/BROAD
BAND...SO THE MOST FAVORED PART OF THE FORECAST AREA IS NORTHWEST
INDIANA. HAVE FORECAST SNOWFALL AMOUNTS AT ONE HALF TO A LITTLE
OVER AN INCH FROM FOWLER UP TO VALPARAISO...WITH SOME POTENTIAL
FOR LESSER ACCUMULATION BACK IN EASTERN IL.
MTF
LONG TERM...TONIGHT THROUGH NEXT SATURDAY...
HIGH PRESSURE SPREADS ACROSS THE CENTRAL PLAINS THIS AFTERNOON AND
REACHES INTO UPPER MISSISSIPPI RIVER VALLEY TONIGHT. DRIER AIR
ASSOCIATED WITH THE HIGH WILL HELP PUSH PRECIP EAST OF THE CWA
TONIGHT. SKIES WILL ALSO CLEAR ALLOWING TEMPS TO FALL INTO THE
TEENS TO SINGLE DIGITS. WENT A DEGREE OR TWO HIGHER THAN GUIDANCE
SINCE THE MODELS BELIEVE THERE IS A FRESH SNOW PACK ON THE GROUND.
HOWEVER FAIRLY CONFIDENT THAT IT WILL BE A CHILLY NIGHT SINCE WINDS
DIMINISH AND SKIES CLEAR. GUIDANCE KEEPS THE IMAGINARY SNOWPACK
THROUGH MID WEEK SO KEPT TEMPS SLIGHTLY ABOVE GUIDANCE THROUGH MID
WEEK.
THE HIGH PRESSURE BECOMES CENTERED OVER CENTRAL IL TUESDAY. ALOFT
THE DEEP TROUGH REMAINS OVER THE WESTERN HALF OF THE US THROUGH
TUESDAY NIGHT. IT THEN FINALLY MARCHES NORTH AND A CLOSED LOW FORMS
OVER TEXAS MID WEEK. THE DOWNSTREAM SIDE OF THE TROUGH WILL BE OVER
THE CWA THROUGH TUESDAY AS WELL LIMITING HOW MUCH OF THE ARCTIC AIR
INFILTRATES THE CWA. AS SUCH HIGH TEMPS THROUGH MID WEEK WILL BE
SLOWLY RISING TO ARND 30 DEGREES. WINDS TURN SOUTHWEST ON TUESDAY
WHICH WILL HELP TEMPS RISE TO AROUND FREEZING AND THEN AT OR
SLIGHTLY ABOVE FREEZING WEDNESDAY.
THE NORTHERN PART OF THE TROUGH PASSES OVERHEAD TUESDAY NIGHT WITH A
SECOND WAVE PASSING TO THE NORTH WEDNESDAY. A SURFACE LOW WILL MOVE
OVER SOUTHERN ONTARIO ON WEDNESDAY WITH PRECIP REMAINING TO OUR
NORTH. THE LOWS COLD FRONT SWINGS THROUGH THE CWA WEDNESDAY NIGHT
INTO THURSDAY MORNING WITH AN ABRUPT WIND SHIFT TO THE NORTHWEST AND
COOLER TEMPS. GUIDANCE SUGGESTS 850 MB TEMPS WILL FALL TO ARND -10C
WITH THE MUCH COLDER AIR REMAINING TO OUR NORTH. AS SUCH UPPER 20S
TO AROUND FREEZING TEMPS ARE EXPECTED THURSDAY. KEPT THE FRONT
PASSAGE DRY YET AGAIN. FORECAST SOUNDINGS INDICATE MOISTURE WILL BE
LIMITED WITH DRY CONDITIONS ABOVE 850MB. MAY SEE SOME PATCHY
DRIZZLE OR FREEZING DRIZZLE FORM ALONG THE COLD FRONT BUT NOT
EXPECTING ANYTHING WIDESPREAD OR MEASURABLE AT THIS POINT. THE
UPPER LEVEL VORTICITY STREAMER DOES CROSS SOUTHERN LAKE MICHIGAN SO
WILL HAVE TO MONITOR TO SEE IF IT COMES ANY FARTHER SOUTH AND
PROVIDES ANY ADDITIONAL SUPPORT.
HIGH PRESSURE PASSES THROUGH CENTRAL IL THURSDAY NIGHT INTO FRIDAY
WITH WINDS BECOMING SOUTHWEST BEHIND IT. THEN A WEAK LOW SYSTEM
APPROACHES FROM THE NORTHWEST LATE THIS WEEK. THE GFS FEATURES A
SURFACE LOW MOVING THROUGH SOUTHERN WI FRIDAY MORNING WHILE THE
ECMWF HAS A MUCH WEAKER WAVE OF ENERGY. GIVEN THE DISCONTINUITY DID
NOT INCLUDE PRECIP ON FRIDAY. A SECOND LOW IS PROGGED TO MOVE
THROUGH THE GREAT LAKES SATURDAY BUT DIFFERENCES IN TIMING AND
LOCATION ONCE AGAIN LED ME TO KEEP A DRY FORECAST GOING.
THE UPPER LEVEL JET REMAINS TO OUR NORTH WHICH WILL KEEP THE COLD
AIR TO OUR NORTH. MAX TEMPS FOR LATE THIS WEEK LOOK AROUND NORMAL
WITH ABOVE NORMAL LOW TEMPS.
JEE
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 18Z...
* LOWER END MVFR CEILINGS IMPROVING TO UPPER END OF MVFR RANGE BY
LATE AFTERNOON...GOING VFR BY EARLY EVENING.
* SLIGHT CHANCE OF A LITTLE VERY LIGHT SNOW OR FLURRIES THIS
AFTERNOON AT ORD WHILE VERY LIGHT SNOW LIKELY AT MDW BUT NO
SIGNIFICANT REDUCTIONS IN VISIBILITY AT EITHER TERMINAL.
* NNW WIND INCREASING SLIGHTLY THIS AFTERNOON AND BECOMING
MODESTLY GUSTY TO 16-18KT LATER AFTERNOON.
TRS
//DISCUSSION...UPDATED 18Z...
AS RAP OUTPUT CONTINUES TO DO A DECENT JOB IN HANDLING LOCATION
OF REFLECTIVITY HAVE FOLLOWED LATEST AVAILABLE VERSION /16Z/ AS
BASIS OF AFTERNOON AND EARLY EVENING FORECAST.
A SHORT WAVE HAS LIFTED FROM OVER FAR NORTHEAST TX AND SOUTHWEST
OK TO NORTHEASTERN AR AND SOUTHEASTERN MO DURING THE MORNING...
AND IS PROGGED TO MOVE NORTHEAST TO NORTHERN IL BY 00Z. HEAVIEST
PRECIPITATION WAS WELL TO THE SE THROUGH SW OF THE REGION...
CLOSER TO THE LOWER LEVEL BAROCLINIC ZONE. FURTHER NORTH...RADAR
ECHOES CONTINUE TO ADVANCE FROM CENTRAL IL TO THE FAR SOUTH TIP
OF LAKE MI AND NORTHWEST AND WEST CENTRAL IN AS THE SHORT WAVE
APPROACHES.
LOOP OF THE RAP COMPOSITE REFLECTIVITY FORECASTS SHOWS THE
NORTHWESTERN EDGE OF THE PRECIPITATION SHIELD MAKING NO FURTHER
NORTHWARD PROGRESS THIS AFTERNOON AND JUST GLANCING MDW BEFORE
MOVING OFF TO THE EAST BY EVENING AS SOUTHWEST WINDS VEER TO
WEST-SOUTHWEST AND WESTERLY IN THE LAYER FROM 1.5 TO 2.5 KM AGL
AND ADVECTING IN COLDER AND DRIER AIR FOLLOWING AN 850 HPA TROUGH
AXIS. THIS WILL ALSO RESULT IN SUBSIDENCE IN THE LOWER LAYERS AND
ANTICIPATE LOSS OF THE MVFR CEILINGS BY EARLY TO MID EVENING.
AS THE 700 HPA TROUGH MOVES ACROSS THE LOCAL AREA LATE THIS
EVENING SKIES SHOULD BECOME SKC TO SCT AS SUBSIDENCE EXPANDS UP
IN TO THE UPPER LEVELS.
TRS
//ORD AND MDW CONFIDENCE...UPDATED 18Z...
* MEDIUM CONFIDENCE IN CEILING TRENDS.
* HIGH CONFIDENCE IN AREA OF -SN MAINLY NORTHEAST TROUGH SOUTHWEST
OF ORD VICINITY.
* HIGH CONFIDENCE IN P6SM VISIBILITY AT ORD.
* MEDIUM CONFIDENCE OF P6SM VISIBILITY AT MDW THIS AFTERNOON.
* HIGH CONFIDENCE IN P6SM VISIBILITY AT MDW TONIGHT INTO MONDAY.
* HIGH CONFIDENCE IN WIND TRENDS.
TRS
//OUTLOOK FOR ORD/MDW FOR 00Z TUESDAY-12Z SUNDAY...UPDATED 12Z...
MONDAY NIGHT THROUGH FRIDAY...PREDOMINANTLY VFR.
MTF
&&
.MARINE...
227 AM CST
AN ACTIVE PERIOD WILL CONTINUE OVER LAKE MICHIGAN THIS UPCOMING
WEEK...WITH GALES LOOKING INCREASINGLY LIKELY FOR TUESDAY NIGHT AND
WEDNESDAY. THIS MORNING...LOW PRESSURE LIES OVER EAST CENTRAL
INDIANA WHILE A BROAD AREA OF HIGH PRESSURE SPANS THE NORTHERN
PLAINS. THIS LEAVES SOUTHERN PORTIONS OF LAKE MICHIGAN IN A MODEST
NORTHERLY GRADIENT...WHICH SHOULD DIMINISH GRADUALLY TODAY AND
TOMORROW AS HIGH PRESSURE GRADUALLY EXPANDS EASTWARD INFLUENCING
THE WESTERN GREAT LAKES REGION. THIS WILL LEAD TO A DOWNWARD TREND
IN WIND SPEEDS AS WIND DIRECTION TRENDS TO MORE NORTHWEST THEN
WESTERLY. WINDS WILL BEGIN TO TURN SOUTHWESTERLY AND INCREASE
AGAIN ON TUESDAY AS LOW PRESSURE QUICKLY MOVES EAST ACROSS THE
CANADIAN PRAIRIES...AND INTO THE NORTHERN GREAT LAKES REGION
TUESDAY NIGHT. NAM/GFS GUIDANCE IS IN DECENT AGREEMENT ON A MORE
SOUTHERLY AND DEEPER TRACK OF THE LOW AS COMPARED TO THE MORE
OPEN/NORTHERLY ECMWF. LIKEWISE...NAM/GFS GUIDANCE BOTH SHOWING
STRONG GALES PARTICULARLY ACROSS THE NORTHERN HALF OF THE LAKE
TUESDAY NIGHT INTO WEDNESDAY WHILE THE ECMWF HINTS TOWARDS AT
LEAST LOWER END GALES FOR THIS PERIOD. NORTHWEST/WEST WINDS WILL
REMAIN ELEVATED THROUGH PORTIONS OF THE DAY THURSDAY...BEFORE
FINALLY DIMINISHING AS BROAD AREA OF HIGH PRESSURE BUILDS ACROSS
THE MISSISSIPPI VALLEY WITH RIDGING EXTENDING NORTH INTO THE
WESTERN GREAT LAKES. BMD
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...SMALL CRAFT ADVISORY...INDIANA NEARSHORE WATERS UNTIL 11 AM MONDAY.
&&
$$
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
1050 AM CST SUN JAN 13 2013
.DISCUSSION...
1049 AM CST
FOR MORNING UPDATE...
ONLY MINOR CHANGES TO GOING FORECAST THIS MORNING.
FORECAST AREA REMAINS EAST OF LARGE SCALE UPPER TROUGH AXIS...
BENEATH SOUTHWEST-NORTHEAST ORIENTED UPPER JET AXIS AND LOW-MID
LEVEL BAROCLINIC ZONE WHICH STRETCHES FROM THE SOUTHERN PLAINS TO
THE GREAT LAKES REGION. SHORT WAVE TROUGH WHICH BROUGHT FREEZING
RAIN/SLEET TO THE AREA LAST NIGHT HAS LIFTED WELL TO THE NORTHEAST
OF THE AREA WITH ITS ASSOCIATED SURFACE LOW OVER WESTERN LAKE
ONTARIO AT MID-MORNING...WHILE ANOTHER JET STREAK AND LOW-AMPLITUDE
MID-LEVEL WAVE WAS NOTED UPSTREAM APPROACHING THE LOWER MISSOURI
VALLEY. THIS WAVE IS EXPECTED TO CONTINUE TO PROPAGATE NORTHEAST TO
THE GREAT LAKES THROUGH THIS EVENING...WITH WEAK SURFACE WAVE OVER
NORTHERN MISSISSIPPI RIPPLING NORTHEAST ALONG THE SURFACE FRONT INTO
THE UPPER OHIO VALLEY BY EARLY THIS EVENING.
12Z SOUNDINGS FROM LOCATIONS UPSTREAM INDICATE A LACK OF SOLID DEEP
MOISTURE AS BEST MOIST PLUME HAS NOW MOVED EAST OF OUR LOCAL AREA
PER WATER VAPOR IMAGERY...THOUGH A PERIOD OF MODERATE MID/UPPER
LEVEL FORCING IS DEPICTED BY VARIOUS MODELS WITH THE APPROACHING
WAVE WHICH WILL HELP MOISTEN AT LEAST PORTIONS OF THE COLUMN ACROSS
THE SOUTHEASTERN PARTS OF THE CWA THIS AFTERNOON. AREA OF INCREASING
RADAR RETURNS ACROSS SOUTHEAST MO AND SOUTHWESTERN IL ARE EXPECTED
TO SPREAD NORTHEAST ACROSS EAST CENTRAL IL AND NORTHWEST INDIANA
DURING THE MID-LATE AFTERNOON HOURS...WITH THE POTENTIAL FOR SOME
LIGHT SNOW AND PERHAPS EVEN A LITTLE LIGHT SLEET GIVEN LAYER OF ILX
12Z SOUNDING STILL AROUND 0 DEG C BETWEEN ABOUT 750-850 MB. 12Z
WRF-NAM TIME SECTIONS FOR GYY DEPICT SOME DECENT MID-LEVEL OMEGA
WITHIN GOOD DENDRITIC GROWTH ZONE FOR A TIME...AS WELL AS FAIRLY
STEEP LAPSE RATES AND EVEN A LITTLE ELEVATED CAPE ABOVE 600 MB...
THOUGH DRY LAYERS BELOW SUGGEST PRECIP MAY STRUGGLE TO GET TOO
IMPRESSIVE. STILL...POSSIBILITY EXISTS FOR SOME MINOR ACCUMS OF A
FEW TENTHS TO PERHAPS LESS THAN AN INCH ACROSS IL AREAS MAINLY EAST
OF I-57 AND EASTWARD INTO NORTHWEST INDIANA. FATHER WEST...ONLY A
FEW FLURRIES EXPECTED WITH DEEPER MOISTURE REALLY LACKING.
UPDATED NDFD GRIDS/ZFP ALREADY AVAILABLE.
RATZER
&&
.PREV DISCUSSION...
340 AM CST
THE FORECAST CONCERNS ARE SOME LINGERING FZDZ POSSIBILITY THIS
MORNING AND THEN SNOW CHANCES THIS AFTERNOON ACROSS MAINLY
NORTHWEST IN. BEYOND THAT...FAIRLY QUIESCENT WEATHER AHEAD FOR
THIS WEEK.
EARLY MORNING WATER VAPOR DEPICTS THE MID-LEVEL SUBTROPICAL
MOISTURE PLUME SHIFTING VERY SLOWLY EAST FROM THE AREA IN ADVANCE
OF THE UPPER LEVEL LONG WAVE TROUGH ACROSS CENTRAL NORTH AMERICA.
THE LEAD SHORT WAVE IMPULSE RESPONSIBLE FOR LAST NIGHTS FREEZING
RAIN AND SLEET IN IL HAS LIFTED NORTHEAST INTO LOWER MI. THIS TOOK
THE MID-LEVEL MOISTURE SUPPORT FOR MOST OF THE CRYSTAL PRODUCTION
WITH IT...SO SNOW HAS CEASED. THE ASSOCIATED SURFACE LOW IS
LIFTING NORTHEAST ACROSS LAKE ERIE THIS MORNING WITH CONTINUED
COLD AIR ADVECTION OOZING IN ACROSS THE FORECAST AREA. RESIDUAL
MOISTURE AND SOME TRANSIENT ANALYZED OMEGA REMAINS IN THE LOWEST
SEVERAL THOUSAND FEET AND HAS PRODUCED PATCHES OF FZDZ. LOOKING AT
THE RAP AND OTHER HIGH RES SHORT TERM GUIDANCE...THE AREA ALONG
AND EAST OF I-57 WOULD BE SLIGHTLY MORE FAVORED THAN ELSEWHERE FOR
THESE PATCHES TO CONTINUE THROUGH MID-MORNING...BUT THEY SHOULD BE
LIGHT. WHILE THERE ARE INEVITABLY PLACES WITH ICY ROADS AFTER
LAST NIGHTS FREEZING PRECIP AND SLEET/SNOW...FURTHER ACCUMULATING
PRECIP THIS MORNING IS UNLIKELY IN THESE AREAS...SO HAVE LET THE
WINTER WEATHER ADVISORY GO.
ANOTHER SOMEWHAT SHEARED IMPULSE IS SEEN ACROSS OK/WESTERN AR
EARLY THIS MORNING WITHIN THE STRONG RIBBON OF UPPER LEVEL
SOUTHWESTERLIES AHEAD OF THE UPPER TROUGH. A 500MB SPEED MAX OF
AROUND 100 KT IN THAT AREA AS OBSERVED ON PROFILERS WILL MOVE
NORTHEAST THROUGH TODAY KEEPING THE WAVE FAIRLY INTACT AS IT
PROGRESSES ALONG A SHARPENING BAROCLINIC ZONE. PRONOUNCED
FRONTOGENESIS IS FORECAST BY BOTH THE NAM AND GFS AND MAKES SENSE
GIVEN THE THERMAL FIELDS PARALLEL ORIENTATION TO THE UPPER JET
AND THE WAVES PATH. LOOKING AT NAM CROSS SECTIONS...THERE IS
QUITE A BIT OF INSTABILITY FORECAST IN THE 700-550MB LAYER WHICH
IS JUST ABOVE AND WITHIN THE FORECAST THERMALLY INDUCED
CIRCULATION. WITH THE MOISTURE STILL ANOMALOUSLY HIGH IN THE MID-
LEVELS...WOULD EXPECT THE SUPPORT TO BE ENOUGH FOR SNOW TO
DEVELOP IN THE FAR EASTERN IL/WESTERN TO NORTHWEST INDIANA REGION
THIS AFTERNOON. SATELLITE TRENDS INDICATE A LITTLE FURTHER WEST
DEVELOPMENT FROM WHAT GUIDANCE SHOWS IS PLAUSIBLE GIVEN WHERE THE
WAVE IS AT...SO TRIED TO ACCOUNT FOR THAT TOO. THERE WILL BE A
SHARP CUTOFF ON THE WESTERN SIDE OF THIS SNOW AREA/BROAD
BAND...SO THE MOST FAVORED PART OF THE FORECAST AREA IS NORTHWEST
INDIANA. HAVE FORECAST SNOWFALL AMOUNTS AT ONE HALF TO A LITTLE
OVER AN INCH FROM FOWLER UP TO VALPARAISO...WITH SOME POTENTIAL
FOR LESSER ACCUMULATION BACK IN EASTERN IL.
MTF
LONG TERM...TONIGHT THROUGH NEXT SATURDAY...
HIGH PRESSURE SPREADS ACROSS THE CENTRAL PLAINS THIS AFTERNOON AND
REACHES INTO UPPER MISSISSIPPI RIVER VALLEY TONIGHT. DRIER AIR
ASSOCIATED WITH THE HIGH WILL HELP PUSH PRECIP EAST OF THE CWA
TONIGHT. SKIES WILL ALSO CLEAR ALLOWING TEMPS TO FALL INTO THE
TEENS TO SINGLE DIGITS. WENT A DEGREE OR TWO HIGHER THAN GUIDANCE
SINCE THE MODELS BELIEVE THERE IS A FRESH SNOW PACK ON THE GROUND.
HOWEVER FAIRLY CONFIDENT THAT IT WILL BE A CHILLY NIGHT SINCE WINDS
DIMINISH AND SKIES CLEAR. GUIDANCE KEEPS THE IMAGINARY SNOWPACK
THROUGH MID WEEK SO KEPT TEMPS SLIGHTLY ABOVE GUIDANCE THROUGH MID
WEEK.
THE HIGH PRESSURE BECOMES CENTERED OVER CENTRAL IL TUESDAY. ALOFT
THE DEEP TROUGH REMAINS OVER THE WESTERN HALF OF THE US THROUGH
TUESDAY NIGHT. IT THEN FINALLY MARCHES NORTH AND A CLOSED LOW FORMS
OVER TEXAS MID WEEK. THE DOWNSTREAM SIDE OF THE TROUGH WILL BE OVER
THE CWA THROUGH TUESDAY AS WELL LIMITING HOW MUCH OF THE ARCTIC AIR
INFILTRATES THE CWA. AS SUCH HIGH TEMPS THROUGH MID WEEK WILL BE
SLOWLY RISING TO ARND 30 DEGREES. WINDS TURN SOUTHWEST ON TUESDAY
WHICH WILL HELP TEMPS RISE TO AROUND FREEZING AND THEN AT OR
SLIGHTLY ABOVE FREEZING WEDNESDAY.
THE NORTHERN PART OF THE TROUGH PASSES OVERHEAD TUESDAY NIGHT WITH A
SECOND WAVE PASSING TO THE NORTH WEDNESDAY. A SURFACE LOW WILL MOVE
OVER SOUTHERN ONTARIO ON WEDNESDAY WITH PRECIP REMAINING TO OUR
NORTH. THE LOWS COLD FRONT SWINGS THROUGH THE CWA WEDNESDAY NIGHT
INTO THURSDAY MORNING WITH AN ABRUPT WIND SHIFT TO THE NORTHWEST AND
COOLER TEMPS. GUIDANCE SUGGESTS 850 MB TEMPS WILL FALL TO ARND -10C
WITH THE MUCH COLDER AIR REMAINING TO OUR NORTH. AS SUCH UPPER 20S
TO AROUND FREEZING TEMPS ARE EXPECTED THURSDAY. KEPT THE FRONT
PASSAGE DRY YET AGAIN. FORECAST SOUNDINGS INDICATE MOISTURE WILL BE
LIMITED WITH DRY CONDITIONS ABOVE 850MB. MAY SEE SOME PATCHY
DRIZZLE OR FREEZING DRIZZLE FORM ALONG THE COLD FRONT BUT NOT
EXPECTING ANYTHING WIDESPREAD OR MEASURABLE AT THIS POINT. THE
UPPER LEVEL VORTICITY STREAMER DOES CROSS SOUTHERN LAKE MICHIGAN SO
WILL HAVE TO MONITOR TO SEE IF IT COMES ANY FARTHER SOUTH AND
PROVIDES ANY ADDITIONAL SUPPORT.
HIGH PRESSURE PASSES THROUGH CENTRAL IL THURSDAY NIGHT INTO FRIDAY
WITH WINDS BECOMING SOUTHWEST BEHIND IT. THEN A WEAK LOW SYSTEM
APPROACHES FROM THE NORTHWEST LATE THIS WEEK. THE GFS FEATURES A
SURFACE LOW MOVING THROUGH SOUTHERN WI FRIDAY MORNING WHILE THE
ECMWF HAS A MUCH WEAKER WAVE OF ENERGY. GIVEN THE DISCONTINUITY DID
NOT INCLUDE PRECIP ON FRIDAY. A SECOND LOW IS PROGGED TO MOVE
THROUGH THE GREAT LAKES SATURDAY BUT DIFFERENCES IN TIMING AND
LOCATION ONCE AGAIN LED ME TO KEEP A DRY FORECAST GOING.
THE UPPER LEVEL JET REMAINS TO OUR NORTH WHICH WILL KEEP THE COLD
AIR TO OUR NORTH. MAX TEMPS FOR LATE THIS WEEK LOOK AROUND NORMAL
WITH ABOVE NORMAL LOW TEMPS.
JEE
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 16Z...
* LOW END MVFR CIGS...POSSIBLY BRIEFLY IFR...THROUGH EARLY THIS
AFTERNOON AND THEN GRADUAL IMPROVEMENT INTO EARLY THIS EVE.
* SMALL CHANCE FOR -SN THIS AFTERNOON MAINLY E-S OF IMMEDIATE MDW
AREA.
* WINDS INCREASING SLIGHTLY THIS AFTERNOON AND BECOMING GUSTS BY
MID TO LATE AFTERNOON.
MTF/TRS
//DISCUSSION...UPDATED 14Z...
RAP OUTPUT SEEMS TO HAVE HANDLING ECHO LOCATION OVER THE LAST FEW
HOURS AND HAS AN AREA EXPANDING FROM FAR SE MO NORTHEASTWARD
ACROSS SOUTHERN AND EASTERN IL INTO NORTHERN IN DURING MID
MORNING TO EARLY AFTERNOON. THIS KEEPS MOST IF NOT ALL
SIGNIFICANT PRECIPITATION TO THE E THROUGH SE OF ORD AND MDW...
WITH GYY HAVING BEST CHANCE OF SEEING SOME -SN MID TO LATE
AFTERNOON AS THE SHORT WAVE OVER FAR NE TX AND SW OK CONTINUES TO
LIFT NORTHEASTWARD TO THE MID MS VALLEY BY 14.00Z.
PREVIOUS DISCUSSION...UPDATED 12Z...
LOW PRESSURE OVER LAKE ERIE WILL CONTINUE TO PROGRESS NORTHEAST
TODAY. REMNANT AMPLE LOW-LEVEL MOISTURE AND SOME WEAK FORCING HAS
AIDED IN A RE-EXPANSION OF DRIZZLE THIS MORNING. THIS SHOULD BE
SOMEWHAT TRANSIENT...BUT WHERE IT OCCURS WILL BE ENOUGH TO
POTENTIALLY CREATE IFR CIGS AND VISBYS. A STRONG UPPER JET OVER
THE AREA WILL BRING A DISTURBANCE OVER THE REGION THIS AFTERNOON.
MOST OF THE LIGHT SNOW WITH THIS DURING THE AFTERNOON WILL REMAIN
TO THE SOUTHEAST OF THE AIRPORTS...WITH GYY AND MDW POTENTIALLY
BEING THE EXCEPTIONS. SMALL ACCUMULATION WILL BE POSSIBLE AT GYY.
LOW CIGS WILL BE STEADY THIS MORNING BEFORE LIKELY SHOWING SOME
IMPROVEMENT THIS AFTERNOON AS DRIER AIR PUSHES EASTWARD IN THE
BOUNDARY LAYER. WINDS WILL SLOWLY BACK TO WNW THIS AFTERNOON AND
INCREASE IN GUSTINESS AS COLD AIR ADVECTION INCREASES IN THE WAKE
OF THE WAVE.
//ORD AND MDW CONFIDENCE...UPDATED 16Z...
* MEDIUM CONFIDENCE IN CIG TRENDS.
* MEDIUM CONFIDENCE IN AREA OF -SN DURING MID TO LATE AFTERNOON
STAYING TO E THROUGH SE OF IMMEDIATE CHI AREA...POSSIBLY SOME
VERY LIGHT SNOW OR FLURRIES AT MDW.
* HIGH CONFIDENCE IN WIND TRENDS.
TRS
//OUTLOOK FOR ORD/MDW FOR 00Z TUESDAY-12Z SUNDAY...UPDATED 12Z...
MONDAY NIGHT THROUGH FRIDAY...PREDOMINANTLY VFR.
MTF
&&
.MARINE...
227 AM CST
AN ACTIVE PERIOD WILL CONTINUE OVER LAKE MICHIGAN THIS UPCOMING
WEEK...WITH GALES LOOKING INCREASINGLY LIKELY FOR TUESDAY NIGHT AND
WEDNESDAY. THIS MORNING...LOW PRESSURE LIES OVER EAST CENTRAL
INDIANA WHILE A BROAD AREA OF HIGH PRESSURE SPANS THE NORTHERN
PLAINS. THIS LEAVES SOUTHERN PORTIONS OF LAKE MICHIGAN IN A MODEST
NORTHERLY GRADIENT...WHICH SHOULD DIMINISH GRADUALLY TODAY AND
TOMORROW AS HIGH PRESSURE GRADUALLY EXPANDS EASTWARD INFLUENCING
THE WESTERN GREAT LAKES REGION. THIS WILL LEAD TO A DOWNWARD TREND
IN WIND SPEEDS AS WIND DIRECTION TRENDS TO MORE NORTHWEST THEN
WESTERLY. WINDS WILL BEGIN TO TURN SOUTHWESTERLY AND INCREASE
AGAIN ON TUESDAY AS LOW PRESSURE QUICKLY MOVES EAST ACROSS THE
CANADIAN PRAIRIES...AND INTO THE NORTHERN GREAT LAKES REGION
TUESDAY NIGHT. NAM/GFS GUIDANCE IS IN DECENT AGREEMENT ON A MORE
SOUTHERLY AND DEEPER TRACK OF THE LOW AS COMPARED TO THE MORE
OPEN/NORTHERLY ECMWF. LIKEWISE...NAM/GFS GUIDANCE BOTH SHOWING
STRONG GALES PARTICULARLY ACROSS THE NORTHERN HALF OF THE LAKE
TUESDAY NIGHT INTO WEDNESDAY WHILE THE ECMWF HINTS TOWARDS AT
LEAST LOWER END GALES FOR THIS PERIOD. NORTHWEST/WEST WINDS WILL
REMAIN ELEVATED THROUGH PORTIONS OF THE DAY THURSDAY...BEFORE
FINALLY DIMINISHING AS BROAD AREA OF HIGH PRESSURE BUILDS ACROSS
THE MISSISSIPPI VALLEY WITH RIDGING EXTENDING NORTH INTO THE
WESTERN GREAT LAKES. BMD
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...SMALL CRAFT ADVISORY...INDIANA NEARSHORE WATERS UNTIL 11 AM MONDAY.
&&
$$
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
1038 AM CST SUN JAN 13 2013
.DISCUSSION...
340 AM CST
THE FORECAST CONCERNS ARE SOME LINGERING FZDZ POSSIBILITY THIS
MORNING AND THEN SNOW CHANCES THIS AFTERNOON ACROSS MAINLY
NORTHWEST IN. BEYOND THAT...FAIRLY QUIESCENT WEATHER AHEAD FOR
THIS WEEK.
EARLY MORNING WATER VAPOR DEPICTS THE MID-LEVEL SUBTROPICAL
MOISTURE PLUME SHIFTING VERY SLOWLY EAST FROM THE AREA IN ADVANCE
OF THE UPPER LEVEL LONG WAVE TROUGH ACROSS CENTRAL NORTH AMERICA.
THE LEAD SHORT WAVE IMPULSE RESPONSIBLE FOR LAST NIGHTS FREEZING
RAIN AND SLEET IN IL HAS LIFTED NORTHEAST INTO LOWER MI. THIS TOOK
THE MID-LEVEL MOISTURE SUPPORT FOR MOST OF THE CRYSTAL PRODUCTION
WITH IT...SO SNOW HAS CEASED. THE ASSOCIATED SURFACE LOW IS
LIFTING NORTHEAST ACROSS LAKE ERIE THIS MORNING WITH CONTINUED
COLD AIR ADVECTION OOZING IN ACROSS THE FORECAST AREA. RESIDUAL
MOISTURE AND SOME TRANSIENT ANALYZED OMEGA REMAINS IN THE LOWEST
SEVERAL THOUSAND FEET AND HAS PRODUCED PATCHES OF FZDZ. LOOKING AT
THE RAP AND OTHER HIGH RES SHORT TERM GUIDANCE...THE AREA ALONG
AND EAST OF I-57 WOULD BE SLIGHTLY MORE FAVORED THAN ELSEWHERE FOR
THESE PATCHES TO CONTINUE THROUGH MID-MORNING...BUT THEY SHOULD BE
LIGHT. WHILE THERE ARE INEVITABLY PLACES WITH ICY ROADS AFTER
LAST NIGHTS FREEZING PRECIP AND SLEET/SNOW...FURTHER ACCUMULATING
PRECIP THIS MORNING IS UNLIKELY IN THESE AREAS...SO HAVE LET THE
WINTER WEATHER ADVISORY GO.
ANOTHER SOMEWHAT SHEARED IMPULSE IS SEEN ACROSS OK/WESTERN AR
EARLY THIS MORNING WITHIN THE STRONG RIBBON OF UPPER LEVEL
SOUTHWESTERLIES AHEAD OF THE UPPER TROUGH. A 500MB SPEED MAX OF
AROUND 100 KT IN THAT AREA AS OBSERVED ON PROFILERS WILL MOVE
NORTHEAST THROUGH TODAY KEEPING THE WAVE FAIRLY INTACT AS IT
PROGRESSES ALONG A SHARPENING BAROCLINIC ZONE. PRONOUNCED
FRONTOGENESIS IS FORECAST BY BOTH THE NAM AND GFS AND MAKES SENSE
GIVEN THE THERMAL FIELDS PARALLEL ORIENTATION TO THE UPPER JET
AND THE WAVES PATH. LOOKING AT NAM CROSS SECTIONS...THERE IS
QUITE A BIT OF INSTABILITY FORECAST IN THE 700-550MB LAYER WHICH
IS JUST ABOVE AND WITHIN THE FORECAST THERMALLY INDUCED
CIRCULATION. WITH THE MOISTURE STILL ANOMALOUSLY HIGH IN THE MID-
LEVELS...WOULD EXPECT THE SUPPORT TO BE ENOUGH FOR SNOW TO
DEVELOP IN THE FAR EASTERN IL/WESTERN TO NORTHWEST INDIANA REGION
THIS AFTERNOON. SATELLITE TRENDS INDICATE A LITTLE FURTHER WEST
DEVELOPMENT FROM WHAT GUIDANCE SHOWS IS PLAUSIBLE GIVEN WHERE THE
WAVE IS AT...SO TRIED TO ACCOUNT FOR THAT TOO. THERE WILL BE A
SHARP CUTOFF ON THE WESTERN SIDE OF THIS SNOW AREA/BROAD
BAND...SO THE MOST FAVORED PART OF THE FORECAST AREA IS NORTHWEST
INDIANA. HAVE FORECAST SNOWFALL AMOUNTS AT ONE HALF TO A LITTLE
OVER AN INCH FROM FOWLER UP TO VALPARAISO...WITH SOME POTENTIAL
FOR LESSER ACCUMULATION BACK IN EASTERN IL.
MTF
LONG TERM...TONIGHT THROUGH NEXT SATURDAY...
HIGH PRESSURE SPREADS ACROSS THE CENTRAL PLAINS THIS AFTERNOON AND
REACHES INTO UPPER MISSISSIPPI RIVER VALLEY TONIGHT. DRIER AIR
ASSOCIATED WITH THE HIGH WILL HELP PUSH PRECIP EAST OF THE CWA
TONIGHT. SKIES WILL ALSO CLEAR ALLOWING TEMPS TO FALL INTO THE
TEENS TO SINGLE DIGITS. WENT A DEGREE OR TWO HIGHER THAN GUIDANCE
SINCE THE MODELS BELIEVE THERE IS A FRESH SNOW PACK ON THE GROUND.
HOWEVER FAIRLY CONFIDENT THAT IT WILL BE A CHILLY NIGHT SINCE WINDS
DIMINISH AND SKIES CLEAR. GUIDANCE KEEPS THE IMAGINARY SNOWPACK
THROUGH MID WEEK SO KEPT TEMPS SLIGHTLY ABOVE GUIDANCE THROUGH MID
WEEK.
THE HIGH PRESSURE BECOMES CENTERED OVER CENTRAL IL TUESDAY. ALOFT
THE DEEP TROUGH REMAINS OVER THE WESTERN HALF OF THE US THROUGH
TUESDAY NIGHT. IT THEN FINALLY MARCHES NORTH AND A CLOSED LOW FORMS
OVER TEXAS MID WEEK. THE DOWNSTREAM SIDE OF THE TROUGH WILL BE OVER
THE CWA THROUGH TUESDAY AS WELL LIMITING HOW MUCH OF THE ARCTIC AIR
INFILTRATES THE CWA. AS SUCH HIGH TEMPS THROUGH MID WEEK WILL BE
SLOWLY RISING TO ARND 30 DEGREES. WINDS TURN SOUTHWEST ON TUESDAY
WHICH WILL HELP TEMPS RISE TO AROUND FREEZING AND THEN AT OR
SLIGHTLY ABOVE FREEZING WEDNESDAY.
THE NORTHERN PART OF THE TROUGH PASSES OVERHEAD TUESDAY NIGHT WITH A
SECOND WAVE PASSING TO THE NORTH WEDNESDAY. A SURFACE LOW WILL MOVE
OVER SOUTHERN ONTARIO ON WEDNESDAY WITH PRECIP REMAINING TO OUR
NORTH. THE LOWS COLD FRONT SWINGS THROUGH THE CWA WEDNESDAY NIGHT
INTO THURSDAY MORNING WITH AN ABRUPT WIND SHIFT TO THE NORTHWEST AND
COOLER TEMPS. GUIDANCE SUGGESTS 850 MB TEMPS WILL FALL TO ARND -10C
WITH THE MUCH COLDER AIR REMAINING TO OUR NORTH. AS SUCH UPPER 20S
TO AROUND FREEZING TEMPS ARE EXPECTED THURSDAY. KEPT THE FRONT
PASSAGE DRY YET AGAIN. FORECAST SOUNDINGS INDICATE MOISTURE WILL BE
LIMITED WITH DRY CONDITIONS ABOVE 850MB. MAY SEE SOME PATCHY
DRIZZLE OR FREEZING DRIZZLE FORM ALONG THE COLD FRONT BUT NOT
EXPECTING ANYTHING WIDESPREAD OR MEASURABLE AT THIS POINT. THE
UPPER LEVEL VORTICITY STREAMER DOES CROSS SOUTHERN LAKE MICHIGAN SO
WILL HAVE TO MONITOR TO SEE IF IT COMES ANY FARTHER SOUTH AND
PROVIDES ANY ADDITIONAL SUPPORT.
HIGH PRESSURE PASSES THROUGH CENTRAL IL THURSDAY NIGHT INTO FRIDAY
WITH WINDS BECOMING SOUTHWEST BEHIND IT. THEN A WEAK LOW SYSTEM
APPROACHES FROM THE NORTHWEST LATE THIS WEEK. THE GFS FEATURES A
SURFACE LOW MOVING THROUGH SOUTHERN WI FRIDAY MORNING WHILE THE
ECMWF HAS A MUCH WEAKER WAVE OF ENERGY. GIVEN THE DISCONTINUITY DID
NOT INCLUDE PRECIP ON FRIDAY. A SECOND LOW IS PROGGED TO MOVE
THROUGH THE GREAT LAKES SATURDAY BUT DIFFERENCES IN TIMING AND
LOCATION ONCE AGAIN LED ME TO KEEP A DRY FORECAST GOING.
THE UPPER LEVEL JET REMAINS TO OUR NORTH WHICH WILL KEEP THE COLD
AIR TO OUR NORTH. MAX TEMPS FOR LATE THIS WEEK LOOK AROUND NORMAL
WITH ABOVE NORMAL LOW TEMPS.
JEE
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 16Z...
* LOW END MVFR CIGS...POSSIBLY BRIEFLY IFR...THROUGH EARLY THIS
AFTERNOON AND THEN GRADUAL IMPROVEMENT INTO EARLY THIS EVE.
* SMALL CHANCE FOR -SN THIS AFTERNOON MAINLY E-S OF IMMEDIATE MDW
AREA.
* WINDS INCREASING SLIGHTLY THIS AFTERNOON AND BECOMING GUSTS BY
MID TO LATE AFTERNOON.
MTF/TRS
//DISCUSSION...UPDATED 14Z...
RAP OUTPUT SEEMS TO HAVE HANDLING ECHO LOCATION OVER THE LAST FEW
HOURS AND HAS AN AREA EXPANDING FROM FAR SE MO NORTHEASTWARD
ACROSS SOUTHERN AND EASTERN IL INTO NORTHERN IN DURING MID
MORNING TO EARLY AFTERNOON. THIS KEEPS MOST IF NOT ALL
SIGNIFICANT PRECIPITATION TO THE E THROUGH SE OF ORD AND MDW...
WITH GYY HAVING BEST CHANCE OF SEEING SOME -SN MID TO LATE
AFTERNOON AS THE SHORT WAVE OVER FAR NE TX AND SW OK CONTINUES TO
LIFT NORTHEASTWARD TO THE MID MS VALLEY BY 14.00Z.
PREVIOUS DISCUSSION...UPDATED 12Z...
LOW PRESSURE OVER LAKE ERIE WILL CONTINUE TO PROGRESS NORTHEAST
TODAY. REMNANT AMPLE LOW-LEVEL MOISTURE AND SOME WEAK FORCING HAS
AIDED IN A RE-EXPANSION OF DRIZZLE THIS MORNING. THIS SHOULD BE
SOMEWHAT TRANSIENT...BUT WHERE IT OCCURS WILL BE ENOUGH TO
POTENTIALLY CREATE IFR CIGS AND VISBYS. A STRONG UPPER JET OVER
THE AREA WILL BRING A DISTURBANCE OVER THE REGION THIS AFTERNOON.
MOST OF THE LIGHT SNOW WITH THIS DURING THE AFTERNOON WILL REMAIN
TO THE SOUTHEAST OF THE AIRPORTS...WITH GYY AND MDW POTENTIALLY
BEING THE EXCEPTIONS. SMALL ACCUMULATION WILL BE POSSIBLE AT GYY.
LOW CIGS WILL BE STEADY THIS MORNING BEFORE LIKELY SHOWING SOME
IMPROVEMENT THIS AFTERNOON AS DRIER AIR PUSHES EASTWARD IN THE
BOUNDARY LAYER. WINDS WILL SLOWLY BACK TO WNW THIS AFTERNOON AND
INCREASE IN GUSTINESS AS COLD AIR ADVECTION INCREASES IN THE WAKE
OF THE WAVE.
//ORD AND MDW CONFIDENCE...UPDATED 16Z...
* MEDIUM CONFIDENCE IN CIG TRENDS.
* MEDIUM CONFIDENCE IN AREA OF -SN DURING MID TO LATE AFTERNOON
STAYING TO E THROUGH SE OF IMMEDIATE CHI AREA...POSSIBLY SOME
VERY LIGHT SNOW OR FLURRIES AT MDW.
* HIGH CONFIDENCE IN WIND TRENDS.
TRS
//OUTLOOK FOR ORD/MDW FOR 00Z TUESDAY-12Z SUNDAY...UPDATED 12Z...
MONDAY NIGHT THROUGH FRIDAY...PREDOMINANTLY VFR.
MTF
&&
.MARINE...
227 AM CST
AN ACTIVE PERIOD WILL CONTINUE OVER LAKE MICHIGAN THIS UPCOMING
WEEK...WITH GALES LOOKING INCREASINGLY LIKELY FOR TUESDAY NIGHT AND
WEDNESDAY. THIS MORNING...LOW PRESSURE LIES OVER EAST CENTRAL
INDIANA WHILE A BROAD AREA OF HIGH PRESSURE SPANS THE NORTHERN
PLAINS. THIS LEAVES SOUTHERN PORTIONS OF LAKE MICHIGAN IN A MODEST
NORTHERLY GRADIENT...WHICH SHOULD DIMINISH GRADUALLY TODAY AND
TOMORROW AS HIGH PRESSURE GRADUALLY EXPANDS EASTWARD INFLUENCING
THE WESTERN GREAT LAKES REGION. THIS WILL LEAD TO A DOWNWARD TREND
IN WIND SPEEDS AS WIND DIRECTION TRENDS TO MORE NORTHWEST THEN
WESTERLY. WINDS WILL BEGIN TO TURN SOUTHWESTERLY AND INCREASE
AGAIN ON TUESDAY AS LOW PRESSURE QUICKLY MOVES EAST ACROSS THE
CANADIAN PRAIRIES...AND INTO THE NORTHERN GREAT LAKES REGION
TUESDAY NIGHT. NAM/GFS GUIDANCE IS IN DECENT AGREEMENT ON A MORE
SOUTHERLY AND DEEPER TRACK OF THE LOW AS COMPARED TO THE MORE
OPEN/NORTHERLY ECMWF. LIKEWISE...NAM/GFS GUIDANCE BOTH SHOWING
STRONG GALES PARTICULARLY ACROSS THE NORTHERN HALF OF THE LAKE
TUESDAY NIGHT INTO WEDNESDAY WHILE THE ECMWF HINTS TOWARDS AT
LEAST LOWER END GALES FOR THIS PERIOD. NORTHWEST/WEST WINDS WILL
REMAIN ELEVATED THROUGH PORTIONS OF THE DAY THURSDAY...BEFORE
FINALLY DIMINISHING AS BROAD AREA OF HIGH PRESSURE BUILDS ACROSS
THE MISSISSIPPI VALLEY WITH RIDGING EXTENDING NORTH INTO THE
WESTERN GREAT LAKES. BMD
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...SMALL CRAFT ADVISORY...INDIANA NEARSHORE WATERS UNTIL 11 AM MONDAY.
&&
$$
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
834 AM CST SUN JAN 13 2013
.DISCUSSION...
340 AM CST
THE FORECAST CONCERNS ARE SOME LINGERING FZDZ POSSIBILITY THIS
MORNING AND THEN SNOW CHANCES THIS AFTERNOON ACROSS MAINLY
NORTHWEST IN. BEYOND THAT...FAIRLY QUIESCENT WEATHER AHEAD FOR
THIS WEEK.
EARLY MORNING WATER VAPOR DEPICTS THE MID-LEVEL SUBTROPICAL
MOISTURE PLUME SHIFTING VERY SLOWLY EAST FROM THE AREA IN ADVANCE
OF THE UPPER LEVEL LONG WAVE TROUGH ACROSS CENTRAL NORTH AMERICA.
THE LEAD SHORT WAVE IMPULSE RESPONSIBLE FOR LAST NIGHTS FREEZING
RAIN AND SLEET IN IL HAS LIFTED NORTHEAST INTO LOWER MI. THIS TOOK
THE MID-LEVEL MOISTURE SUPPORT FOR MOST OF THE CRYSTAL PRODUCTION
WITH IT...SO SNOW HAS CEASED. THE ASSOCIATED SURFACE LOW IS
LIFTING NORTHEAST ACROSS LAKE ERIE THIS MORNING WITH CONTINUED
COLD AIR ADVECTION OOZING IN ACROSS THE FORECAST AREA. RESIDUAL
MOISTURE AND SOME TRANSIENT ANALYZED OMEGA REMAINS IN THE LOWEST
SEVERAL THOUSAND FEET AND HAS PRODUCED PATCHES OF FZDZ. LOOKING AT
THE RAP AND OTHER HIGH RES SHORT TERM GUIDANCE...THE AREA ALONG
AND EAST OF I-57 WOULD BE SLIGHTLY MORE FAVORED THAN ELSEWHERE FOR
THESE PATCHES TO CONTINUE THROUGH MID-MORNING...BUT THEY SHOULD BE
LIGHT. WHILE THERE ARE INEVITABLY PLACES WITH ICY ROADS AFTER
LAST NIGHTS FREEZING PRECIP AND SLEET/SNOW...FURTHER ACCUMULATING
PRECIP THIS MORNING IS UNLIKELY IN THESE AREAS...SO HAVE LET THE
WINTER WEATHER ADVISORY GO.
ANOTHER SOMEWHAT SHEARED IMPULSE IS SEEN ACROSS OK/WESTERN AR
EARLY THIS MORNING WITHIN THE STRONG RIBBON OF UPPER LEVEL
SOUTHWESTERLIES AHEAD OF THE UPPER TROUGH. A 500MB SPEED MAX OF
AROUND 100 KT IN THAT AREA AS OBSERVED ON PROFILERS WILL MOVE
NORTHEAST THROUGH TODAY KEEPING THE WAVE FAIRLY INTACT AS IT
PROGRESSES ALONG A SHARPENING BAROCLINIC ZONE. PRONOUNCED
FRONTOGENESIS IS FORECAST BY BOTH THE NAM AND GFS AND MAKES SENSE
GIVEN THE THERMAL FIELDS PARALLEL ORIENTATION TO THE UPPER JET
AND THE WAVES PATH. LOOKING AT NAM CROSS SECTIONS...THERE IS
QUITE A BIT OF INSTABILITY FORECAST IN THE 700-550MB LAYER WHICH
IS JUST ABOVE AND WITHIN THE FORECAST THERMALLY INDUCED
CIRCULATION. WITH THE MOISTURE STILL ANOMALOUSLY HIGH IN THE MID-
LEVELS...WOULD EXPECT THE SUPPORT TO BE ENOUGH FOR SNOW TO
DEVELOP IN THE FAR EASTERN IL/WESTERN TO NORTHWEST INDIANA REGION
THIS AFTERNOON. SATELLITE TRENDS INDICATE A LITTLE FURTHER WEST
DEVELOPMENT FROM WHAT GUIDANCE SHOWS IS PLAUSIBLE GIVEN WHERE THE
WAVE IS AT...SO TRIED TO ACCOUNT FOR THAT TOO. THERE WILL BE A
SHARP CUTOFF ON THE WESTERN SIDE OF THIS SNOW AREA/BROAD
BAND...SO THE MOST FAVORED PART OF THE FORECAST AREA IS NORTHWEST
INDIANA. HAVE FORECAST SNOWFALL AMOUNTS AT ONE HALF TO A LITTLE
OVER AN INCH FROM FOWLER UP TO VALPARAISO...WITH SOME POTENTIAL
FOR LESSER ACCUMULATION BACK IN EASTERN IL.
MTF
LONG TERM...TONIGHT THROUGH NEXT SATURDAY...
HIGH PRESSURE SPREADS ACROSS THE CENTRAL PLAINS THIS AFTERNOON AND
REACHES INTO UPPER MISSISSIPPI RIVER VALLEY TONIGHT. DRIER AIR
ASSOCIATED WITH THE HIGH WILL HELP PUSH PRECIP EAST OF THE CWA
TONIGHT. SKIES WILL ALSO CLEAR ALLOWING TEMPS TO FALL INTO THE
TEENS TO SINGLE DIGITS. WENT A DEGREE OR TWO HIGHER THAN GUIDANCE
SINCE THE MODELS BELIEVE THERE IS A FRESH SNOW PACK ON THE GROUND.
HOWEVER FAIRLY CONFIDENT THAT IT WILL BE A CHILLY NIGHT SINCE WINDS
DIMINISH AND SKIES CLEAR. GUIDANCE KEEPS THE IMAGINARY SNOWPACK
THROUGH MID WEEK SO KEPT TEMPS SLIGHTLY ABOVE GUIDANCE THROUGH MID
WEEK.
THE HIGH PRESSURE BECOMES CENTERED OVER CENTRAL IL TUESDAY. ALOFT
THE DEEP TROUGH REMAINS OVER THE WESTERN HALF OF THE US THROUGH
TUESDAY NIGHT. IT THEN FINALLY MARCHES NORTH AND A CLOSED LOW FORMS
OVER TEXAS MID WEEK. THE DOWNSTREAM SIDE OF THE TROUGH WILL BE OVER
THE CWA THROUGH TUESDAY AS WELL LIMITING HOW MUCH OF THE ARCTIC AIR
INFILTRATES THE CWA. AS SUCH HIGH TEMPS THROUGH MID WEEK WILL BE
SLOWLY RISING TO ARND 30 DEGREES. WINDS TURN SOUTHWEST ON TUESDAY
WHICH WILL HELP TEMPS RISE TO AROUND FREEZING AND THEN AT OR
SLIGHTLY ABOVE FREEZING WEDNESDAY.
THE NORTHERN PART OF THE TROUGH PASSES OVERHEAD TUESDAY NIGHT WITH A
SECOND WAVE PASSING TO THE NORTH WEDNESDAY. A SURFACE LOW WILL MOVE
OVER SOUTHERN ONTARIO ON WEDNESDAY WITH PRECIP REMAINING TO OUR
NORTH. THE LOWS COLD FRONT SWINGS THROUGH THE CWA WEDNESDAY NIGHT
INTO THURSDAY MORNING WITH AN ABRUPT WIND SHIFT TO THE NORTHWEST AND
COOLER TEMPS. GUIDANCE SUGGESTS 850 MB TEMPS WILL FALL TO ARND -10C
WITH THE MUCH COLDER AIR REMAINING TO OUR NORTH. AS SUCH UPPER 20S
TO AROUND FREEZING TEMPS ARE EXPECTED THURSDAY. KEPT THE FRONT
PASSAGE DRY YET AGAIN. FORECAST SOUNDINGS INDICATE MOISTURE WILL BE
LIMITED WITH DRY CONDITIONS ABOVE 850MB. MAY SEE SOME PATCHY
DRIZZLE OR FREEZING DRIZZLE FORM ALONG THE COLD FRONT BUT NOT
EXPECTING ANYTHING WIDESPREAD OR MEASURABLE AT THIS POINT. THE
UPPER LEVEL VORTICITY STREAMER DOES CROSS SOUTHERN LAKE MICHIGAN SO
WILL HAVE TO MONITOR TO SEE IF IT COMES ANY FARTHER SOUTH AND
PROVIDES ANY ADDITIONAL SUPPORT.
HIGH PRESSURE PASSES THROUGH CENTRAL IL THURSDAY NIGHT INTO FRIDAY
WITH WINDS BECOMING SOUTHWEST BEHIND IT. THEN A WEAK LOW SYSTEM
APPROACHES FROM THE NORTHWEST LATE THIS WEEK. THE GFS FEATURES A
SURFACE LOW MOVING THROUGH SOUTHERN WI FRIDAY MORNING WHILE THE
ECMWF HAS A MUCH WEAKER WAVE OF ENERGY. GIVEN THE DISCONTINUITY DID
NOT INCLUDE PRECIP ON FRIDAY. A SECOND LOW IS PROGGED TO MOVE
THROUGH THE GREAT LAKES SATURDAY BUT DIFFERENCES IN TIMING AND
LOCATION ONCE AGAIN LED ME TO KEEP A DRY FORECAST GOING.
THE UPPER LEVEL JET REMAINS TO OUR NORTH WHICH WILL KEEP THE COLD
AIR TO OUR NORTH. MAX TEMPS FOR LATE THIS WEEK LOOK AROUND NORMAL
WITH ABOVE NORMAL LOW TEMPS.
JEE
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 14Z...
* LOW END MVFR CIGS...POSSIBLY BRIEFLY IFR...THROUGH EARLY THIS
AFTERNOON AND THEN GRADUAL IMPROVEMENT INTO EARLY THIS EVE.
* SMALL POTENTIAL FOR FREEZING DRIZZLE THIS MORNING.
* SMALL CHANCE FOR -SN THIS AFTERNOON.
* WINDS TURNING WNW WITH SOMEWHAT MORE FREQUENT GUSTS BY MID TO
LATE AFTERNOON.
MTF/TRS
//DISCUSSION...UPDATED 14Z...
RAP OUTPUT SEEMS TO HAVE HANDLING ECHO LOCATION OVER THE LAST FEW
HOURS AND HAS AN AREA EXPANDING FROM FAR SE MO NORTHEASTWARD
ACROSS SOUTHERN AND EASTERN IL INTO NORTHERN IN DURING MID
MORNING TO EARLY AFTERNOON. THIS KEEPS MOST IF NOT ALL
SIGNIFICANT PRECIPITATION TO THE E THROUGH SE OF ORD AND MDW...
WITH GYY HAVING BEST CHANCE OF SEEING SOME -SN MID TO LATE
AFTERNOON AS THE SHORT WAVE OVER FAR NE TX AND SW OK CONTINUES TO
LIFT NORTHEASTWARD TO THE MID MS VALLEY BY 14.00Z.
PREVIOUS DISCUSSION...UPDATED 12Z...
LOW PRESSURE OVER LAKE ERIE WILL CONTINUE TO PROGRESS NORTHEAST
TODAY. REMNANT AMPLE LOW-LEVEL MOISTURE AND SOME WEAK FORCING HAS
AIDED IN A RE-EXPANSION OF DRIZZLE THIS MORNING. THIS SHOULD BE
SOMEWHAT TRANSIENT...BUT WHERE IT OCCURS WILL BE ENOUGH TO
POTENTIALLY CREATE IFR CIGS AND VISBYS. A STRONG UPPER JET OVER
THE AREA WILL BRING A DISTURBANCE OVER THE REGION THIS AFTERNOON.
MOST OF THE LIGHT SNOW WITH THIS DURING THE AFTERNOON WILL REMAIN
TO THE SOUTHEAST OF THE AIRPORTS...WITH GYY AND MDW POTENTIALLY
BEING THE EXCEPTIONS. SMALL ACCUMULATION WILL BE POSSIBLE AT GYY.
LOW CIGS WILL BE STEADY THIS MORNING BEFORE LIKELY SHOWING SOME
IMPROVEMENT THIS AFTERNOON AS DRIER AIR PUSHES EASTWARD IN THE
BOUNDARY LAYER. WINDS WILL SLOWLY BACK TO WNW THIS AFTERNOON AND
INCREASE IN GUSTINESS AS COLD AIR ADVECTION INCREASES IN THE WAKE
OF THE WAVE.
//ORD AND MDW CONFIDENCE...UPDATED 14Z...
* MEDIUM CONFIDENCE IN CIG TRENDS.
* LOW CONFIDENCE IN ANY FREEZING DRIZZLE THIS MORNING.
* MODERATE CONFIDENCE IN AREA OF -SN DURING MID TO LATE AFTERNOON
STAYING TO E THROUGH SE OF IMMEDIATE CHI AREA.
* MEDIUM CONFIDENCE IN WIND TRENDS.
//OUTLOOK FOR ORD/MDW FOR 00Z TUESDAY-12Z SUNDAY...UPDATED 12Z...
MONDAY NIGHT THROUGH FRIDAY...PREDOMINANTLY VFR.
MTF
&&
.MARINE...
227 AM CST
AN ACTIVE PERIOD WILL CONTINUE OVER LAKE MICHIGAN THIS UPCOMING
WEEK...WITH GALES LOOKING INCREASINGLY LIKELY FOR TUESDAY NIGHT AND
WEDNESDAY. THIS MORNING...LOW PRESSURE LIES OVER EAST CENTRAL
INDIANA WHILE A BROAD AREA OF HIGH PRESSURE SPANS THE NORTHERN
PLAINS. THIS LEAVES SOUTHERN PORTIONS OF LAKE MICHIGAN IN A MODEST
NORTHERLY GRADIENT...WHICH SHOULD DIMINISH GRADUALLY TODAY AND
TOMORROW AS HIGH PRESSURE GRADUALLY EXPANDS EASTWARD INFLUENCING
THE WESTERN GREAT LAKES REGION. THIS WILL LEAD TO A DOWNWARD TREND
IN WIND SPEEDS AS WIND DIRECTION TRENDS TO MORE NORTHWEST THEN
WESTERLY. WINDS WILL BEGIN TO TURN SOUTHWESTERLY AND INCREASE
AGAIN ON TUESDAY AS LOW PRESSURE QUICKLY MOVES EAST ACROSS THE
CANADIAN PRAIRIES...AND INTO THE NORTHERN GREAT LAKES REGION
TUESDAY NIGHT. NAM/GFS GUIDANCE IS IN DECENT AGREEMENT ON A MORE
SOUTHERLY AND DEEPER TRACK OF THE LOW AS COMPARED TO THE MORE
OPEN/NORTHERLY ECMWF. LIKEWISE...NAM/GFS GUIDANCE BOTH SHOWING
STRONG GALES PARTICULARLY ACROSS THE NORTHERN HALF OF THE LAKE
TUESDAY NIGHT INTO WEDNESDAY WHILE THE ECMWF HINTS TOWARDS AT
LEAST LOWER END GALES FOR THIS PERIOD. NORTHWEST/WEST WINDS WILL
REMAIN ELEVATED THROUGH PORTIONS OF THE DAY THURSDAY...BEFORE
FINALLY DIMINISHING AS BROAD AREA OF HIGH PRESSURE BUILDS ACROSS
THE MISSISSIPPI VALLEY WITH RIDGING EXTENDING NORTH INTO THE
WESTERN GREAT LAKES. BMD
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...SMALL CRAFT ADVISORY...LMZ741-LMZ742 UNTIL 10 AM SUNDAY.
SMALL CRAFT ADVISORY...INDIANA NEARSHORE WATERS UNTIL 11 AM MONDAY.
&&
$$
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
557 AM CST SUN JAN 13 2013
.DISCUSSION...
340 AM CST
THE FORECAST CONCERNS ARE SOME LINGERING FZDZ POSSIBILITY THIS
MORNING AND THEN SNOW CHANCES THIS AFTERNOON ACROSS MAINLY
NORTHWEST IN. BEYOND THAT...FAIRLY QUIESCENT WEATHER AHEAD FOR
THIS WEEK.
EARLY MORNING WATER VAPOR DEPICTS THE MID-LEVEL SUBTROPICAL
MOISTURE PLUME SHIFTING VERY SLOWLY EAST FROM THE AREA IN ADVANCE
OF THE UPPER LEVEL LONG WAVE TROUGH ACROSS CENTRAL NORTH AMERICA.
THE LEAD SHORT WAVE IMPULSE RESPONSIBLE FOR LAST NIGHTS FREEZING
RAIN AND SLEET IN IL HAS LIFTED NORTHEAST INTO LOWER MI. THIS TOOK
THE MID-LEVEL MOISTURE SUPPORT FOR MOST OF THE CRYSTAL PRODUCTION
WITH IT...SO SNOW HAS CEASED. THE ASSOCIATED SURFACE LOW IS
LIFTING NORTHEAST ACROSS LAKE ERIE THIS MORNING WITH CONTINUED
COLD AIR ADVECTION OOZING IN ACROSS THE FORECAST AREA. RESIDUAL
MOISTURE AND SOME TRANSIENT ANALYZED OMEGA REMAINS IN THE LOWEST
SEVERAL THOUSAND FEET AND HAS PRODUCED PATCHES OF FZDZ. LOOKING AT
THE RAP AND OTHER HIGH RES SHORT TERM GUIDANCE...THE AREA ALONG
AND EAST OF I-57 WOULD BE SLIGHTLY MORE FAVORED THAN ELSEWHERE FOR
THESE PATCHES TO CONTINUE THROUGH MID-MORNING...BUT THEY SHOULD BE
LIGHT. WHILE THERE ARE INEVITABLY PLACES WITH ICY ROADS AFTER
LAST NIGHTS FREEZING PRECIP AND SLEET/SNOW...FURTHER ACCUMULATING
PRECIP THIS MORNING IS UNLIKELY IN THESE AREAS...SO HAVE LET THE
WINTER WEATHER ADVISORY GO.
ANOTHER SOMEWHAT SHEARED IMPULSE IS SEEN ACROSS OK/WESTERN AR
EARLY THIS MORNING WITHIN THE STRONG RIBBON OF UPPER LEVEL
SOUTHWESTERLIES AHEAD OF THE UPPER TROUGH. A 500MB SPEED MAX OF
AROUND 100 KT IN THAT AREA AS OBSERVED ON PROFILERS WILL MOVE
NORTHEAST THROUGH TODAY KEEPING THE WAVE FAIRLY INTACT AS IT
PROGRESSES ALONG A SHARPENING BAROCLINIC ZONE. PRONOUNCED
FRONTOGENESIS IS FORECAST BY BOTH THE NAM AND GFS AND MAKES SENSE
GIVEN THE THERMAL FIELDS PARALLEL ORIENTATION TO THE UPPER JET
AND THE WAVES PATH. LOOKING AT NAM CROSS SECTIONS...THERE IS
QUITE A BIT OF INSTABILITY FORECAST IN THE 700-550MB LAYER WHICH
IS JUST ABOVE AND WITHIN THE FORECAST THERMALLY INDUCED
CIRCULATION. WITH THE MOISTURE STILL ANOMALOUSLY HIGH IN THE MID-
LEVELS...WOULD EXPECT THE SUPPORT TO BE ENOUGH FOR SNOW TO
DEVELOP IN THE FAR EASTERN IL/WESTERN TO NORTHWEST INDIANA REGION
THIS AFTERNOON. SATELLITE TRENDS INDICATE A LITTLE FURTHER WEST
DEVELOPMENT FROM WHAT GUIDANCE SHOWS IS PLAUSIBLE GIVEN WHERE THE
WAVE IS AT...SO TRIED TO ACCOUNT FOR THAT TOO. THERE WILL BE A
SHARP CUTOFF ON THE WESTERN SIDE OF THIS SNOW AREA/BROAD
BAND...SO THE MOST FAVORED PART OF THE FORECAST AREA IS NORTHWEST
INDIANA. HAVE FORECAST SNOWFALL AMOUNTS AT ONE HALF TO A LITTLE
OVER AN INCH FROM FOWLER UP TO VALPARAISO...WITH SOME POTENTIAL
FOR LESSER ACCUMULATION BACK IN EASTERN IL.
MTF
LONG TERM...TONIGHT THROUGH NEXT SATURDAY...
HIGH PRESSURE SPREADS ACROSS THE CENTRAL PLAINS THIS AFTERNOON AND
REACHES INTO UPPER MISSISSIPPI RIVER VALLEY TONIGHT. DRIER AIR
ASSOCIATED WITH THE HIGH WILL HELP PUSH PRECIP EAST OF THE CWA
TONIGHT. SKIES WILL ALSO CLEAR ALLOWING TEMPS TO FALL INTO THE
TEENS TO SINGLE DIGITS. WENT A DEGREE OR TWO HIGHER THAN GUIDANCE
SINCE THE MODELS BELIEVE THERE IS A FRESH SNOW PACK ON THE GROUND.
HOWEVER FAIRLY CONFIDENT THAT IT WILL BE A CHILLY NIGHT SINCE WINDS
DIMINISH AND SKIES CLEAR. GUIDANCE KEEPS THE IMAGINARY SNOWPACK
THROUGH MID WEEK SO KEPT TEMPS SLIGHTLY ABOVE GUIDANCE THROUGH MID
WEEK.
THE HIGH PRESSURE BECOMES CENTERED OVER CENTRAL IL TUESDAY. ALOFT
THE DEEP TROUGH REMAINS OVER THE WESTERN HALF OF THE US THROUGH
TUESDAY NIGHT. IT THEN FINALLY MARCHES NORTH AND A CLOSED LOW FORMS
OVER TEXAS MID WEEK. THE DOWNSTREAM SIDE OF THE TROUGH WILL BE OVER
THE CWA THROUGH TUESDAY AS WELL LIMITING HOW MUCH OF THE ARCTIC AIR
INFILTRATES THE CWA. AS SUCH HIGH TEMPS THROUGH MID WEEK WILL BE
SLOWLY RISING TO ARND 30 DEGREES. WINDS TURN SOUTHWEST ON TUESDAY
WHICH WILL HELP TEMPS RISE TO AROUND FREEZING AND THEN AT OR
SLIGHTLY ABOVE FREEZING WEDNESDAY.
THE NORTHERN PART OF THE TROUGH PASSES OVERHEAD TUESDAY NIGHT WITH A
SECOND WAVE PASSING TO THE NORTH WEDNESDAY. A SURFACE LOW WILL MOVE
OVER SOUTHERN ONTARIO ON WEDNESDAY WITH PRECIP REMAINING TO OUR
NORTH. THE LOWS COLD FRONT SWINGS THROUGH THE CWA WEDNESDAY NIGHT
INTO THURSDAY MORNING WITH AN ABRUPT WIND SHIFT TO THE NORTHWEST AND
COOLER TEMPS. GUIDANCE SUGGESTS 850 MB TEMPS WILL FALL TO ARND -10C
WITH THE MUCH COLDER AIR REMAINING TO OUR NORTH. AS SUCH UPPER 20S
TO AROUND FREEZING TEMPS ARE EXPECTED THURSDAY. KEPT THE FRONT
PASSAGE DRY YET AGAIN. FORECAST SOUNDINGS INDICATE MOISTURE WILL BE
LIMITED WITH DRY CONDITIONS ABOVE 850MB. MAY SEE SOME PATCHY
DRIZZLE OR FREEZING DRIZZLE FORM ALONG THE COLD FRONT BUT NOT
EXPECTING ANYTHING WIDESPREAD OR MEASURABLE AT THIS POINT. THE
UPPER LEVEL VORTICITY STREAMER DOES CROSS SOUTHERN LAKE MICHIGAN SO
WILL HAVE TO MONITOR TO SEE IF IT COMES ANY FARTHER SOUTH AND
PROVIDES ANY ADDITIONAL SUPPORT.
HIGH PRESSURE PASSES THROUGH CENTRAL IL THURSDAY NIGHT INTO FRIDAY
WITH WINDS BECOMING SOUTHWEST BEHIND IT. THEN A WEAK LOW SYSTEM
APPROACHES FROM THE NORTHWEST LATE THIS WEEK. THE GFS FEATURES A
SURFACE LOW MOVING THROUGH SOUTHERN WI FRIDAY MORNING WHILE THE
ECMWF HAS A MUCH WEAKER WAVE OF ENERGY. GIVEN THE DISCONTINUITY DID
NOT INCLUDE PRECIP ON FRIDAY. A SECOND LOW IS PROGGED TO MOVE
THROUGH THE GREAT LAKES SATURDAY BUT DIFFERENCES IN TIMING AND
LOCATION ONCE AGAIN LED ME TO KEEP A DRY FORECAST GOING.
THE UPPER LEVEL JET REMAINS TO OUR NORTH WHICH WILL KEEP THE COLD
AIR TO OUR NORTH. MAX TEMPS FOR LATE THIS WEEK LOOK AROUND NORMAL
WITH ABOVE NORMAL LOW TEMPS.
JEE
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 12Z...
* LOW END MVFR CIGS...POSSIBLY BRIEFLY IFR...THROUGH EARLY THIS
AFTERNOON AND THEN GRADUAL IMPROVEMENT INTO EARLY THIS EVE.
* PATHCHY FREEZING DRIZZLE THIS MORNING.
* A SMALL CHANCE FOR AFTERNOON -SN.
* WINDS TURNING WNW WITH SOMEWHAT MORE FREQUENT GUSTS BY MID TO
LATE AFTERNOON.
//DISCUSSION...UPDATED 12Z...
LOW PRESSURE OVER LAKE ERIE WILL CONTINUE TO PROGRESS NORTHEAST
TODAY. REMNANT AMPLE LOW-LEVEL MOISTURE AND SOME WEAK FORCING HAS
AIDED IN A RE-EXPANSION OF DRIZZLE THIS MORNING. THIS SHOULD BE
SOMEWHAT TRANSIENT...BUT WHERE IT OCCURS WILL BE ENOUGH TO
POTENTIALLY CREATE IFR CIGS AND VISBYS. A STRONG UPPER JET OVER
THE AREA WILL BRING A DISTURBANCE OVER THE REGION THIS AFTERNOON.
MOST OF THE LIGHT SNOW WITH THIS DURING THE AFTERNOON WILL REMAIN
TO THE SOUTHEAST OF THE AIRPORTS...WITH GYY AND MDW POTENTIALLY
BEING THE EXCEPTIONS. SMALL ACCUMULATION WILL BE POSSIBLE AT GYY.
LOW CIGS WILL BE STEADY THIS MORNING BEFORE LIKELY SHOWING SOME
IMPROVEMENT THIS AFTERNOON AS DRIER AIR PUSHES EASTWARD IN THE
BOUNDARY LAYER. WINDS WILL SLOWLY BACK TO WNW THIS AFTERNOON AND
INCREASE IN GUSTINESS AS COLD AIR ADVECTION INCREASES IN THE WAKE
OF THE WAVE.
//ORD AND MDW CONFIDENCE...UPDATED 12Z...
* MEDIUM CONFIDENCE IN CIG TRENDS. LOW CONFIDENCE IN DURATION OF
LOW CLOUDS.
* LOW CONFIDENCE IN FREEZING DRIZZLE THIS MORNING AND -SN THIS
AFTERNOON. IF FREEZING DRIZZLE OCCURS...MEDIUM CONFIDENCE
VISIBILITY WILL DROP TO BELOW SM.
* MEDIUM CONFIDENCE IN WIND TRENDS.
//OUTLOOK FOR ORD/MDW FOR 00Z TUESDAY-12Z SUNDAY...UPDATED 12Z...
MONDAY NIGHT THROUGH FRIDAY...PREDOMINANTLY VFR.
MTF
&&
.MARINE...
227 AM CST
AN ACTIVE PERIOD WILL CONTINUE OVER LAKE MICHIGAN THIS UPCOMING
WEEK...WITH GALES LOOKING INCREASINGLY LIKELY FOR TUESDAY NIGHT AND
WEDNESDAY. THIS MORNING...LOW PRESSURE LIES OVER EAST CENTRAL
INDIANA WHILE A BROAD AREA OF HIGH PRESSURE SPANS THE NORTHERN
PLAINS. THIS LEAVES SOUTHERN PORTIONS OF LAKE MICHIGAN IN A MODEST
NORTHERLY GRADIENT...WHICH SHOULD DIMINISH GRADUALLY TODAY AND
TOMORROW AS HIGH PRESSURE GRADUALLY EXPANDS EASTWARD INFLUENCING
THE WESTERN GREAT LAKES REGION. THIS WILL LEAD TO A DOWNWARD TREND
IN WIND SPEEDS AS WIND DIRECTION TRENDS TO MORE NORTHWEST THEN
WESTERLY. WINDS WILL BEGIN TO TURN SOUTHWESTERLY AND INCREASE
AGAIN ON TUESDAY AS LOW PRESSURE QUICKLY MOVES EAST ACROSS THE
CANADIAN PRAIRIES...AND INTO THE NORTHERN GREAT LAKES REGION
TUESDAY NIGHT. NAM/GFS GUIDANCE IS IN DECENT AGREEMENT ON A MORE
SOUTHERLY AND DEEPER TRACK OF THE LOW AS COMPARED TO THE MORE
OPEN/NORTHERLY ECMWF. LIKEWISE...NAM/GFS GUIDANCE BOTH SHOWING
STRONG GALES PARTICULARLY ACROSS THE NORTHERN HALF OF THE LAKE
TUESDAY NIGHT INTO WEDNESDAY WHILE THE ECMWF HINTS TOWARDS AT
LEAST LOWER END GALES FOR THIS PERIOD. NORTHWEST/WEST WINDS WILL
REMAIN ELEVATED THROUGH PORTIONS OF THE DAY THURSDAY...BEFORE
FINALLY DIMINISHING AS BROAD AREA OF HIGH PRESSURE BUILDS ACROSS
THE MISSISSIPPI VALLEY WITH RIDGING EXTENDING NORTH INTO THE
WESTERN GREAT LAKES. BMD
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...SMALL CRAFT ADVISORY...LMZ741-LMZ742 UNTIL 10 AM SUNDAY.
SMALL CRAFT ADVISORY...INDIANA NEARSHORE WATERS UNTIL 11 AM MONDAY.
&&
$$
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
348 AM CST SUN JAN 13 2013
.DISCUSSION...
340 AM CST
THE FORECAST CONCERNS ARE SOME LINGERING FZDZ POSSIBILITY THIS
MORNING AND THEN SNOW CHANCES THIS AFTERNOON ACROSS MAINLY
NORTHWEST IN. BEYOND THAT...FAIRLY QUIESCENT WEATHER AHEAD FOR
THIS WEEK.
EARLY MORNING WATER VAPOR DEPICTS THE MID-LEVEL SUBTROPICAL
MOISTURE PLUME SHIFTING VERY SLOWLY EAST FROM THE AREA IN ADVANCE
OF THE UPPER LEVEL LONG WAVE TROUGH ACROSS CENTRAL NORTH AMERICA.
THE LEAD SHORT WAVE IMPULSE RESPONSIBLE FOR LAST NIGHTS FREEZING
RAIN AND SLEET IN IL HAS LIFTED NORTHEAST INTO LOWER MI. THIS TOOK
THE MID-LEVEL MOISTURE SUPPORT FOR MOST OF THE CRYSTAL PRODUCTION
WITH IT...SO SNOW HAS CEASED. THE ASSOCIATED SURFACE LOW IS
LIFTING NORTHEAST ACROSS LAKE ERIE THIS MORNING WITH CONTINUED
COLD AIR ADVECTION OOZING IN ACROSS THE FORECAST AREA. RESIDUAL
MOISTURE AND SOME TRANSIENT ANALYZED OMEGA REMAINS IN THE LOWEST
SEVERAL THOUSAND FEET AND HAS PRODUCED PATCHES OF FZDZ. LOOKING AT
THE RAP AND OTHER HIGH RES SHORT TERM GUIDANCE...THE AREA ALONG
AND EAST OF I-57 WOULD BE SLIGHTLY MORE FAVORED THAN ELSEWHERE FOR
THESE PATCHES TO CONTINUE THROUGH MID-MORNING...BUT THEY SHOULD BE
LIGHT. WHILE THERE ARE INEVITABLY PLACES WITH ICY ROADS AFTER
LAST NIGHTS FREEZING PRECIP AND SLEET/SNOW...FURTHER ACCUMULATING
PRECIP THIS MORNING IS UNLIKELY IN THESE AREAS...SO HAVE LET THE
WINTER WEATHER ADVISORY GO.
ANOTHER SOMEWHAT SHEARED IMPULSE IS SEEN ACROSS OK/WESTERN AR
EARLY THIS MORNING WITHIN THE STRONG RIBBON OF UPPER LEVEL
SOUTHWESTERLIES AHEAD OF THE UPPER TROUGH. A 500MB SPEED MAX OF
AROUND 100 KT IN THAT AREA AS OBSERVED ON PROFILERS WILL MOVE
NORTHEAST THROUGH TODAY KEEPING THE WAVE FAIRLY INTACT AS IT
PROGRESSES ALONG A SHARPENING BAROCLINIC ZONE. PRONOUNCED
FRONTOGENESIS IS FORECAST BY BOTH THE NAM AND GFS AND MAKES SENSE
GIVEN THE THERMAL FIELDS PARALLEL ORIENTATION TO THE UPPER JET
AND THE WAVES PATH. LOOKING AT NAM CROSS SECTIONS...THERE IS
QUITE A BIT OF INSTABILITY FORECAST IN THE 700-550MB LAYER WHICH
IS JUST ABOVE AND WITHIN THE FORECAST THERMALLY INDUCED
CIRCULATION. WITH THE MOISTURE STILL ANOMALOUSLY HIGH IN THE MID-
LEVELS...WOULD EXPECT THE SUPPORT TO BE ENOUGH FOR SNOW TO
DEVELOP IN THE FAR EASTERN IL/WESTERN TO NORTHWEST INDIANA REGION
THIS AFTERNOON. SATELLITE TRENDS INDICATE A LITTLE FURTHER WEST
DEVELOPMENT FROM WHAT GUIDANCE SHOWS IS PLAUSIBLE GIVEN WHERE THE
WAVE IS AT...SO TRIED TO ACCOUNT FOR THAT TOO. THERE WILL BE A
SHARP CUTOFF ON THE WESTERN SIDE OF THIS SNOW AREA/BROAD
BAND...SO THE MOST FAVORED PART OF THE FORECAST AREA IS NORTHWEST
INDIANA. HAVE FORECAST SNOWFALL AMOUNTS AT ONE HALF TO A LITTLE
OVER AN INCH FROM FOWLER UP TO VALPARAISO...WITH SOME POTENTIAL
FOR LESSER ACCUMULATION BACK IN EASTERN IL.
MTF
LONG TERM...TONIGHT THROUGH NEXT SATURDAY...
HIGH PRESSURE SPREADS ACROSS THE CENTRAL PLAINS THIS AFTERNOON AND
REACHES INTO UPPER MISSISSIPPI RIVER VALLEY TONIGHT. DRIER AIR
ASSOCIATED WITH THE HIGH WILL HELP PUSH PRECIP EAST OF THE CWA
TONIGHT. SKIES WILL ALSO CLEAR ALLOWING TEMPS TO FALL INTO THE
TEENS TO SINGLE DIGITS. WENT A DEGREE OR TWO HIGHER THAN GUIDANCE
SINCE THE MODELS BELIEVE THERE IS A FRESH SNOW PACK ON THE GROUND.
HOWEVER FAIRLY CONFIDENT THAT IT WILL BE A CHILLY NIGHT SINCE WINDS
DIMINISH AND SKIES CLEAR. GUIDANCE KEEPS THE IMAGINARY SNOWPACK
THROUGH MID WEEK SO KEPT TEMPS SLIGHTLY ABOVE GUIDANCE THROUGH MID
WEEK.
THE HIGH PRESSURE BECOMES CENTERED OVER CENTRAL IL TUESDAY. ALOFT
THE DEEP TROUGH REMAINS OVER THE WESTERN HALF OF THE US THROUGH
TUESDAY NIGHT. IT THEN FINALLY MARCHES NORTH AND A CLOSED LOW FORMS
OVER TEXAS MID WEEK. THE DOWNSTREAM SIDE OF THE TROUGH WILL BE OVER
THE CWA THROUGH TUESDAY AS WELL LIMITING HOW MUCH OF THE ARCTIC AIR
INFILTRATES THE CWA. AS SUCH HIGH TEMPS THROUGH MID WEEK WILL BE
SLOWLY RISING TO ARND 30 DEGREES. WINDS TURN SOUTHWEST ON TUESDAY
WHICH WILL HELP TEMPS RISE TO AROUND FREEZING AND THEN AT OR
SLIGHTLY ABOVE FREEZING WEDNESDAY.
THE NORTHERN PART OF THE TROUGH PASSES OVERHEAD TUESDAY NIGHT WITH A
SECOND WAVE PASSING TO THE NORTH WEDNESDAY. A SURFACE LOW WILL MOVE
OVER SOUTHERN ONTARIO ON WEDNESDAY WITH PRECIP REMAINING TO OUR
NORTH. THE LOWS COLD FRONT SWINGS THROUGH THE CWA WEDNESDAY NIGHT
INTO THURSDAY MORNING WITH AN ABRUPT WIND SHIFT TO THE NORTHWEST AND
COOLER TEMPS. GUIDANCE SUGGESTS 850 MB TEMPS WILL FALL TO ARND -10C
WITH THE MUCH COLDER AIR REMAINING TO OUR NORTH. AS SUCH UPPER 20S
TO AROUND FREEZING TEMPS ARE EXPECTED THURSDAY. KEPT THE FRONT
PASSAGE DRY YET AGAIN. FORECAST SOUNDINGS INDICATE MOISTURE WILL BE
LIMITED WITH DRY CONDITIONS ABOVE 850MB. MAY SEE SOME PATCHY
DRIZZLE OR FREEZING DRIZZLE FORM ALONG THE COLD FRONT BUT NOT
EXPECTING ANYTHING WIDESPREAD OR MEASURABLE AT THIS POINT. THE
UPPER LEVEL VORTICITY STREAMER DOES CROSS SOUTHERN LAKE MICHIGAN SO
WILL HAVE TO MONITOR TO SEE IF IT COMES ANY FARTHER SOUTH AND
PROVIDES ANY ADDITIONAL SUPPORT.
HIGH PRESSURE PASSES THROUGH CENTRAL IL THURSDAY NIGHT INTO FRIDAY
WITH WINDS BECOMING SOUTHWEST BEHIND IT. THEN A WEAK LOW SYSTEM
APPROACHES FROM THE NORTHWEST LATE THIS WEEK. THE GFS FEATURES A
SURFACE LOW MOVING THROUGH SOUTHERN WI FRIDAY MORNING WHILE THE
ECMWF HAS A MUCH WEAKER WAVE OF ENERGY. GIVEN THE DISCONTINUITY DID
NOT INCLUDE PRECIP ON FRIDAY. A SECOND LOW IS PROGGED TO MOVE
THROUGH THE GREAT LAKES SATURDAY BUT DIFFERENCES IN TIMING AND
LOCATION ONCE AGAIN LED ME TO KEEP A DRY FORECAST GOING.
THE UPPER LEVEL JET REMAINS TO OUR NORTH WHICH WILL KEEP THE COLD
AIR TO OUR NORTH. MAX TEMPS FOR LATE THIS WEEK LOOK AROUND NORMAL
WITH ABOVE NORMAL LOW TEMPS.
JEE
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 09Z...
* PATCHY FZDZ THROUGH DAYBREAK.
* IFR/LOW MVFR CIGS SLOW TO IMPROVE THROUGH THE DAY. THE
POTENTIAL FOR FZDZ AFTER 10Z AS STEADIER PRECIPITATION ENDS.
* A SLIGHT CHANCE FOR -SN LATE THIS AFTERNOON.
* NW WINDS BECOMING WNW THIS AFTERNOON AND GUSTY INTO THE EVE.
//DISCUSSION...UPDATED 06Z...
LOW PRESSURE WILL MOVE NORTHEAST ACROSS INDIANA THROUGH DAYBREAK.
THERE APPEARS A WINDOW OF ABOUT 3-4 MORE HOURS /THROUGH 09Z-10Z/
OF STEADIER PRECIP. THE ATMOSPHERE WILL GRADUALLY CONTINUE TO COOL
THROUGH OVERNIGHT...WITH THE PRECIP TYPE OF FZRA/PL AT CHICAGOLAND
TAF SITES LIKELY CHANGING TO A MIX WITH SNOW IN THE FINAL COUPLE
HOURS. RFD...DPA...AND ORD ALL MAY SEE A SHORT-LIVED BOUT OF
MODERATE SNOW BEFORE THE STEADIER PRECIP ENDS. AS THE DEEP
MOISTURE DECREASES BEHIND THE SYSTEM BY 10Z...FORCING FOR PRECIP
DOES NOT COMPLETELY WANE SO THE CHANCE FOR FREEZING DRIZZLE
EXISTS. CONFIDENCE REMAINS LOW ON THIS...BUT WITH SUCH A DEEP
SATURATED LAYER AND A TURBULENT FLOW WITHIN IT...CONTINUE TO LEAN
TO THE SIDE OF CAUTION. WITHIN THE CONTINUED STRONG UPPER JET...AN
UPPER LEVEL DISTURBANCE WILL MOVE NORTHEAST OVER INDIANA THIS
AFTERNOON AND PRESENT THE CHANCE FOR LIGHT SNOW. CONFIDENCE ON
THIS IS LOW AND WILL FURTHER BE ASSESSED OVERNIGHT FOR THE 12Z
TAFS.
CIGS ARE A BIT OF A MESS OUT THERE...BUT ANTICIPATING A QUICK
LOWERING THROUGH THE NEXT COUPLE HOURS WITH LOW CONDITIONS
PERSISTING THROUGH THE MORNING. CONFIDENCE IS LOW ON EXACTLY WHEN
IMPROVEMENT TO MVFR WILL OCCUR AND THEN TO VFR.
NW WINDS WILL CONTINUE THROUGH THIS MORNING WITH SPORADIC GUSTS.
AS COLD AIR ADVECTION ENSUES A LITTLE MORE THIS AFTERNOON GUSTS
WILL LIKELY BECOME MORE PERIODIC AS THE WINDS SHIFT TO WNW.
//ORD AND MDW CONFIDENCE...UPDATED 09Z...
* LOW CONFIDENCE ON ANY MORE FZDZ.
* MEDIUM CONFIDENCE IN CIG TRENDS WITH LOW CONFIDENCE IN DURATION
OF IFR CIGS.
* MEDIUM CONFIDENCE THAT ACCUMULATING -SN WILL STAY TO THE
SOUTHEAST OF ORD AND MDW THIS AFTERNOON.
* MEDIUM CONFIDENCE IN WIND TRENDS.
//OUTLOOK FOR ORD/MDW FOR 12Z MONDAY-12Z SATURDAY...UPDATED 00Z...
MONDAY THROUGH FRIDAY...PREDOMINANTLY VFR.
MTF
&&
.MARINE...
227 AM CST
AN ACTIVE PERIOD WILL CONTINUE OVER LAKE MICHIGAN THIS UPCOMING
WEEK...WITH GALES LOOKING INCREASINGLY LIKELY FOR TUESDAY NIGHT AND
WEDNESDAY. THIS MORNING...LOW PRESSURE LIES OVER EAST CENTRAL
INDIANA WHILE A BROAD AREA OF HIGH PRESSURE SPANS THE NORTHERN
PLAINS. THIS LEAVES SOUTHERN PORTIONS OF LAKE MICHIGAN IN A MODEST
NORTHERLY GRADIENT...WHICH SHOULD DIMINISH GRADUALLY TODAY AND
TOMORROW AS HIGH PRESSURE GRADUALLY EXPANDS EASTWARD INFLUENCING
THE WESTERN GREAT LAKES REGION. THIS WILL LEAD TO A DOWNWARD TREND
IN WIND SPEEDS AS WIND DIRECTION TRENDS TO MORE NORTHWEST THEN
WESTERLY. WINDS WILL BEGIN TO TURN SOUTHWESTERLY AND INCREASE
AGAIN ON TUESDAY AS LOW PRESSURE QUICKLY MOVES EAST ACROSS THE
CANADIAN PRAIRIES...AND INTO THE NORTHERN GREAT LAKES REGION
TUESDAY NIGHT. NAM/GFS GUIDANCE IS IN DECENT AGREEMENT ON A MORE
SOUTHERLY AND DEEPER TRACK OF THE LOW AS COMPARED TO THE MORE
OPEN/NORTHERLY ECMWF. LIKEWISE...NAM/GFS GUIDANCE BOTH SHOWING
STRONG GALES PARTICULARLY ACROSS THE NORTHERN HALF OF THE LAKE
TUESDAY NIGHT INTO WEDNESDAY WHILE THE ECMWF HINTS TOWARDS AT
LEAST LOWER END GALES FOR THIS PERIOD. NORTHWEST/WEST WINDS WILL
REMAIN ELEVATED THROUGH PORTIONS OF THE DAY THURSDAY...BEFORE
FINALLY DIMINISHING AS BROAD AREA OF HIGH PRESSURE BUILDS ACROSS
THE MISSISSIPPI VALLEY WITH RIDGING EXTENDING NORTH INTO THE
WESTERN GREAT LAKES. BMD
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...SMALL CRAFT ADVISORY...LMZ741-LMZ742 UNTIL 10 AM SUNDAY.
SMALL CRAFT ADVISORY...INDIANA NEARSHORE WATERS UNTIL 11 AM MONDAY.
&&
$$
AREA FORECAST DISCUSSION
NWS LINCOLN IL
1206 AM CST SUN JAN 13 2013
.DISCUSSION...
ISSUED 853 PM CST SAT JAN 12 2013
TRICKY PRECIPITATION TYPE FORECAST TONIGHT ACROSS MUCH OF
CENTRAL/SOUTHEAST ILLINOIS FOR THE REST OF THE NIGHT. SIGNS ARE
STARTING TO POINT TO MORE OF A FREEZING RAIN PROBLEM IN MUCH OF
THE FORECAST AREA. 00Z ILX SOUNDING...AS WELL AS 00Z NAM AND
LATEST RAP SOUNDINGS...SUGGEST A MORE SIGNIFICANT ELEVATED WARM
LAYER THAN WAS PREVIOUSLY ANTICIPATED. IN ADDITION...SURFACE
TEMPERATURES ARE FALLING TO 32 DEGREES OR COLDER A LITTLE QUICKER
AS WELL. THE SURFACE FREEZING LINE CURRENTLY RESIDES IN THE
VICINITY OF THE I-55 CORRIDOR.
THIS DIFFERENCE IN THERMAL PROFILE WILL REQUIRE A FEW TWEAKS TO
THE FORECAST. THE RISK FOR APPRECIABLE SLEET APPEARS TO HAVE FADED
AS IT LOOKS LIKE THE ELEVATED WARM SHOULD COOL QUICKLY WHEN IT
DOES SO...SIGNALING A RAPID CHANGE OVER FROM RAIN/FREEZING RAIN TO
SNOW. SO...PLAN TO REMOVE MOST MENTIONS OF SLEET. THE MORE
PRONOUNCED ELEVATED WARM LAYER AND MORE RAPID SURFACE COOLING HAS
RESULTED IN FREEZING RAIN FALLING FURTHER WEST THAN ANTICIPATED
AND WILL MAKE ADJUSTMENTS TO PUSH FREEZING RAIN WEST TO THE
ILLINOIS RIVER VALLEY. FINALLY...WILL HAVE TO PUSH THE CHANGE OVER
FROM RAIN TO FREEZING RAIN EAST A BIT MORE QUICKLY.
THERE IS SOME CONCERN WITH FREEZING RAIN BECOMING MORE OF A
PREDOMINANT WEATHER TYPE THAT MORE SIGNIFICANT ICING MAY BECOME A
THREAT. HOWEVER...FEEL THAT THE RAPID END OF THE HEAVIER
PRECIPITATION...BY SHORTLY AFTER MIDNIGHT...WILL PRECLUDE THE
NEED OF AN UPGRADE TO A WARNING. THIS THREAT WILL BE WATCHED
CLOSELY.
BAK
&&
.AVIATION...
ISSUED 1206 AM CST SUN JAN 13 2013
PRECIPITATION RAPIDLY TAPERING OFF ACROSS THE CENTRAL ILLINOIS
TERMINALS. HOWEVER...PATCHY FREEZING DRIZZLE IS LIKELY TO LINGER
FOR THE REST OF THE NIGHT AND INTO THIS MORNING. ANOTHER
DISTURBANCE WILL MOVE THROUGH THE AREA LATER TODAY...BRINGING A
CHANCE OF LIGHT SNOW TO ALL TERMINALS ASIDE FROM KPIA.
PREDOMINANTLY IFR CONDITIONS ARE EXPECTED OVERNIGHT...WITH A
GRADUAL IMPROVEMENT TO MVFR OR EVEN VFR AS THE DISTURBANCE DEPARTS
LATER TODAY.
BAK
&&
.PREV DISCUSSION...
QUICK MOVING WEATHER SYSTEM TO BRING A PERIOD OF FREEZING
RAIN...SLEET AND SNOW THIS EVENING/OVERNIGHT IN ALL AREAS BUT FAR
EAST CENTRAL AND SOUTHEAST IL WHERE HEAVY RAINFALL IS A THREAT.
SHORT TERM...TONIGHT THROUGH TUESDAY NIGHT
UPPER WAVE OF INTEREST BEGINNING TO EJECT NORTHEAST OUT OF THE BASE
OF THE TROF OVER THE SOUTHWEST PORTION OF THE COUNTRY WITH MODELS
ACCELERATING THE FEATURE NORTHEAST THRU THE LOWER GREAT LAKES BY
SUNDAY MORNING. THAT IS ABOUT THE ONLY SAVING GRACE WITH THE UPPER
WAVE IS THE FACT THAT IT WILL BE A QUICK MOVER...OTHERWISE WE WOULD
BE SEEING A LARGE AREA OF SIGNIFICANT ICING OVER PARTS OF CENTRAL IL
LATER TONIGHT. EVEN SO...THE NAM-WRF SOUNDINGS ARE SHOWING A MUCH
LARGER AND LONGER LASTING WARM LAYER (6-8 DEGREES DEPICTED ON THE
RAPID REFRESH MODEL AT SPI-BMI LATER THIS EVE) BETWEEN 800 AND 700 MB
THAN BEFORE...WHICH SUGGESTS THE POTENTIAL FOR LONGER DURATION OF
FREEZING RAIN AND SLEET...ESPECIALLY RIGHT UP THE I-55 CORRIDOR LATER
THIS EVENING WHERE A TENTH TO TWO TENTHS OF AN INCH MAY ACCUMULATE.
ONLY MITIGATING FACTORS WILL BE THE SPEED OF THE SYSTEM AND THAT WE
HAVE HAD A COUPLE OF DAYS WITH SURFACE TEMPS IN THE 50S...SO
INITIALLY...ROADWAYS WILL BE WET INTO THE EVENING BEFORE THE TRANSITION
OCCURS.
FURTHER WEST...ROUGHLY WEST OF THE ILLINOIS RIVER...SEEING SOME POTENTIAL
FOR SOME BRIEF MESOSCALE BANDING (NEGATIVE EPV OVER A PRONOUNCED BAND
OF FRONTOGENETICAL FORCING) OF THE PRECIP BEFORE WE LOSE OUR ICE CRYSTALS
AFTER 06Z WHICH WOULD ENHANCE THE SNOWFALL TOTALS. RIGHT NOW WE ARE
LOOKING AT 2-3 INCHES WEST OF THE ILLINOIS RIVER WITH LESSER AMOUNTS AS
YOU HEAD EAST AS SOUNDINGS INDICATE THE WARM LAYER ABOVE 800 MB HOLDS
IN PLACE UNTIL DAWN SUNDAY. BUT BY THEN...MOST FORECAST SOUNDINGS EVEN
INTO EASTERN ILLINOIS INDICATE THE LOSS OFF ICE CRYSTALS WHICH WOULD
SUGGEST THE THREAT FOR MORE FREEZING DRIZZLE OR FLURRIES...DEPENDING
ON HOW DEEP THE COLD LAYER IS IN THE LOWER LEVELS OF THE ATMOSPHERE.
A WINTER WEATHER ADVISORY WILL BE IN EFFECT STARTING EARLY THIS EVENING
WEST AND THEN ALONG THE I-57 CORRIDOR BY MIDNIGHT TO ADDRESS THE THREAT
FOR A COMBINATION OF SNOW...SLEET AND FREEZING RAIN.
ACROSS SOUTHEAST ILLINOIS...THE TRANSPORT OF MOISTURE NORTHWARD INTO
THE AREA AHEAD OF THE SYSTEM IS VERY IMPRESSIVE FOR THE SECOND WEEK
OF JANUARY WITH PRECIP WATER VALUES OF 1.50 INCHES. RAIN WITH ISOLD
THUNDERSTORMS WILL BRING AN ADDITIONAL 1-2 INCHES OF RAIN TO THE
WABASH...LITTLE WABASH AND EMBARRAS BASINS WHICH THREATENS TO BRING
THOSE BASINS TO FLOOD. AS A RESULT...WILL HAVE A FLOOD WATCH FOR OUR
FAR SOUTHEAST COUNTIES UNTIL NOON SUNDAY TO ADDRESS THE INCREASING
THREAT FOR MORE WIDESPREAD RIVER FLOODING.
AS THE WEATHER SYSTEM DEPARTS SUNDAY MORNING...LINGERING FLURRIES OR
FREEZING DRIZZLE WILL COME TO AN END. HOWEVER...MODELS INDICATE A
SECONDARY WAVE ASSOCIATED WITH A 250 MB SPEED MAX WILL PUT FAR EAST
CENTRAL AND ESPECIALLY SOUTHEAST IL IN THE RIGHT REAR QUAD OF THE
JET WHICH WILL ENHANCE THE UPWARD VERTICAL MOTION AND BRING ANOTHER
ROUND OF PRECIP SUNDAY AFTERNOON INTO EARLY EVENING. HAVE UPPED POPS
IN THAT AREA WITH FORECAST SOUNDINGS INDICATING A MESSY MIXTURE OF
SLEET...FREEZING RAIN AND SNOW FOR A BRIEF PERIOD BEFORE THE JET
SUPPORT SHIFTS AWAY FROM THE AREA BY 00Z MONDAY. AFTER THAT...QUIET
BUT COLDER WEATHER WILL PREVAIL THRU THE REMAINDER OF THE SHORT TERM
PERIOD WITH DAYTIME HIGHS IN THE 20S NORTH...TO THE LOW TO MID 30S
FAR SOUTHEAST WITH EARLY MORNING LOWS DIPPING INTO THE TEENS MOST
AREAS.
LONG TERM...WEDNESDAY THROUGH SATURDAY
COLD VORTEX OVER HUDSON BAY FORECAST BY MEDIUM RANGE MODELS TO
EVENTUALLY SHIFT SOUTH BRINGING A SURGE OF ARCTIC AIR INTO THE
GREAT LAKES REGION...BUT TIMING OF THAT OCCURRENCE IS HANDLED A
BIT DIFFERENTLY FROM WHAT WE SAW YESTERDAY WITH A SLOWER TRANSITION
TO THE COLDER PATTERN BY LATE NEXT WEEKEND.
WITH THE 500 MB UPPER LOW IN HUDSON BAY BEING THE DOMINANT WEATHER
FEATURE THIS PERIOD...MOST OF THE SIGNIFICANT WEATHER SYSTEMS WILL
TAKE A MORE SOUTHERLY TRACK WELL SOUTH OF OUR AREA DURING THIS
PERIOD WITH OUR WEATHER COMING FROM THE NORTHWEST. ANY SOUTHEAST
MOVING SHORTWAVE IN THIS FLOW PATTERN WILL BE WEAK AND MOISTURE
STARVED...AS A RESULT...WILL CONTINUE TO KEEP THE EXTENDED DRY
WITH A GRADUAL WARMING TREND AS WE HEAD INTO NEXT WEEK AS THE
CANADIAN UPPER LOW TEMPORARILY WOBBLES BACK TO THE NORTH BEFORE
HEADING SOUTH TOWARDS THE LOWER 48 JUST AFTER THIS FORECAST
PERIOD.
SHORT TERM...07
LONG TERM....SMITH
&&
.ILX WATCHES/WARNINGS/ADVISORIES...
FLOOD WATCH UNTIL NOON CST TODAY FOR ILZ063-067-068-071>073.
WINTER WEATHER ADVISORY UNTIL NOON CST TODAY FOR ILZ027>031-
036>038-040>056-061.
&&
$$
AREA FORECAST DISCUSSION
NWS INDIANAPOLIS IN
248 PM EST SUN JAN 13 2013
.UPDATE...
THE LONG TERM SECTION HAS BEEN UPDATED BELOW.
&&
.SYNOPSIS...
ISSUED AT 326 AM EST SUN JAN 13 2013
COLD FRONT WILL SLOWLY SETTLE SOUTHEAST OF CENTRAL INDIANA TODAY
RESULTING IN THE END OF PRECIPITATION AFTER MIDNIGHT SUNDAY NIGHT
BUT NOT BEFORE HEAVY RAIN CHANGES OVER TO A WINTRY MIX FROM
NORTHWEST TO SOUTHEAST WITH MINOR ICE OR SNOW ACCUMULATION POSSIBLE.
MUCH COLDER MORE SEASONABLE AIR WILL FILTER IN ALONG WITH DRY
WEATHER THROUGH NEXT WEEKEND. THIS WILL ALLOW RIVER FLOODING TO RUN
ITS COURSE.
&&
.NEAR TERM /REST OF TODAY/...
ISSUED AT 1049 AM EST SUN JAN 13 2013
RADAR MOSAIC AND OBSERVATIONS SHOW RAIN STILL FALLING OVER
SOUTHEASTERN FORECAST AREA WITH AREAS OF DRIZZLE OR VERY LIGHT
RAIN OVER THE REST OF THE AREA. AT 11 AM TEMPERATURES RANGED FROM
THE MID 40S IN THE SOUTHEAST TO RIGHT JUST BELOW THE FREEZING MARK
IN THE NORTHWEST. THE COLD FRONT HAS STALLED JUST SOUTH OF THE
AREA AND A SURFACE WAVE IS MOVING ALONG IT INTO THE AREA. THIS
WAVE IS KEEPING THE SUB-FREEZING AIR FROM ADVANCING INTO THE AREA.
FORECAST SOUNDINGS FROM THE RAPID REFRESH AND RAP AS WELL AS THE
NAM SHOW AN INTRUSION OF COLD AIR JUST ABOVE THE SURFACE FROM THE
NORTHWEST WITH A WARM LAYER ABOVE IT AND LOOKS LIKE IT COULD ALLOW
RAIN TO CHANGE OVER OR MIX WITH SLEET IN THE NORTHWEST OVER THE
NEXT COUPLE OF HOURS AND SPREADING SOUTHEAST FROM THERE. SNOW
COULD MIX IN AFTER 1 IN THE NORTHWEST BUT CHANGE OVER TO JUST SNOW
DOESN/T APPEAR LIKELY IN THE NORTHWEST UNTIL AFTER 4 PM. SURFACE
TEMPERATURES HOLDING FAIRLY STEADY OR JUST FALLING SLOWLY OVER THE
NEXT SEVERAL HOURS SO DO NOT SEE A WIDESPREAD RISK FOR FREEZING
RAIN. THE WESTERN COUNTIES WILL SEE THE GREATEST RISK FOR ANY KIND
OF FREEZING RAIN OR FREEZING DRIZZLE BUT STILL DO NOT EXPECT MUCH
IN THE WAY OF ANY ACCUMULATION OF ICE. SOUTHEASTERN COUNTIES CAN
JUST EXPECT RAIN TO INCREASE IN INTENSITY AND COVERAGE THROUGH THE
AFTERNOON AS THE SURFACE WAVE MOVES NORTHEAST ALONG THE FRONT.
WILL CONTINUE WITH THE FLOOD WATCH AS ADDITIONAL HEAVY RAIN COULD
EXACERBATE CURRENT FLOODING SITUATION ACROSS THE AREA...BUT NOT
ANTICIPATING MORE THAN UP TO AN ADDITIONAL HALF INCH IN THE
SOUTHEAST WITH PERHAPS A QUARTER INCH OR LESS NORTH OF I 70.
CHANGE OVER TO SNOW LOOKS FAIRLY LATE...PROBABLY NOT UNTIL THE
TONIGHT PERIOD IN THE CENTRAL AND SOUTH...AND IS FOLLOWED QUICKLY
BY ARRIVAL OF DRY AIR SO DO NOT EXPECT MUCH IN THE WAY OF
ACCUMULATION. COULD SEE LIGHT ACCUMULATIONS OF SLEET IN THE WEST.
&&
.SHORT TERM /MONDAY THROUGH TUESDAY NIGHT/...
ISSUED AT 326 AM EST SUN JAN 13 2013
THE SHORT TERM FOCUS WILL BE MAINLY ON TEMPERATURES AS A VERY DRY
COLUMN WILL BE IN PLACE THROUGH THE PERIOD AS PLAINS HIGH PRESSURE
BUILDS IN ACROSS THE OHIO VALLEY AND LOWER GREAT LAKES RESULTING IN
LITTLE CLOUD COVER AND SLIGHTLY BELOW AVERAGE TEMPERATURES.
OVERALL...00Z MOS NUMBERS LOOK OK. THE ONLY CAVEAT IS THE NAM MOS
LOOKS SEVERAL DEGREES TOO WARM AT BMG BASED ON ITS OTHER FORECASTED
NUMBERS AND THE GFS MOS. ALLBLEND IS A GOOD PROXY. LOOK FOR
AFTERNOON HIGHS IN THE UPPER 20S TO THE MID 30S ON MONDAY AND IN THE
30S ON TUESDAY. OVERNIGHT LOWS WILL BE IN THE UPPER TEENS TO THE
LOWER 20S.
&&
.LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/...
ISSUED AT 248 PM EST SUN JAN 13 2013
DRY SEASONABLE PATTERN SETTING UP FOR THE TAIL END OF THE WEEK...
WITH GROWING SIGNS FOR MUCH COLDER AIR TO ARRIVE ACROSS CENTRAL
INDIANA BY EARLY NEXT WEEK.
UPPER LEVEL PATTERN WILL REMAIN HIGHLY AMPLIFIED THROUGH THE PERIOD
WITH THE POLAR VORTEX INCREASINGLY BECOME A FACTOR IN EXPECTED
WEATHER ACROSS THE OHIO VALLEY AS IT SLIDES TO NEAR JAMES BAY BY
LATE WEEK. UPPER RIDGE AXIS WILL ALIGN OFF THE U S WEST COAST FOR
MUCH OF THE EXTENDED WITH A DOWNSTREAM TROUGH ENCOMPASSING MUCH OF
THE EASTERN PART OF THE COUNTRY AND WITH TIME...AMPLIFYING DUE TO
THE LOCATION OF THE POLAR VORTEX OVER EASTERN CANADA. FOR CENTRAL
INDIANA...CYCLONIC NORTHWEST FLOW ALOFT WILL BRING A DRY COOL
PATTERN FOR LATE WEEK INTO THE WEEKEND. TEMPERATURES ARE LIKELY TO
BE NEAR NORMAL WITH HIGHS IN THE 30S...POSSIBLY WARMING INTO THE
LOWER 40S FRIDAY AND SATURDAY AS THE UPPER TROUGH RELAXES BRIEFLY.
EXTENDED MODEL GUIDANCE CONTINUES TO ADVERTISE A PIECE OF THE POLAR
VORTEX DIVING SOUTH NEAR THE END OF THE FORECAST PERIOD AND WHILE
THE INDIVIDUAL RUNS DIFFER ON TIMING AND LOCATION TO SOME DEGREE...
THE CONSENSUS SOLUTION AGREES ON A TREND TOWARDS A MUCH COLDER
AIRMASS EXPANDING INTO THE GREAT LAKES AND OHIO VALLEY LATE WEEKEND
INTO EARLY NEXT WEEK. CONFIDENCE CONTINUES TO GROW IN THIS SOLUTION
PLAYING OUT CONSIDERING THAT EXTENDED MODELS HAVE BEEN SHOWING THIS
POTENTIAL FOR SEVERAL DAYS NOW...AND THAT THE POLAR VORTEX REMAINS
OVER EASTERN CANADA. BOTH 12Z RUNS OF THE ECMWF/OP GFS TODAY SHOWING
850MB TEMPS TO NEAR -20C BY NEXT MONDAY/TUESDAY.
&&
.AVIATION /DISCUSSION FOR 131800Z TAF ISSUANCE/...
ISSUED AT 1218 PM EST SUN JAN 13 2013
VERY POOR FLYING CONDITIONS WILL CONTINUE THROUGHOUT THE AFTERNOON
AND EARLY EVENING AS PRECIPITATION SLOWLY MIXES WITH AND CHANGES
OVER TO PREDOMINANTLY SLEET AND SNOW. VFR CONDITIONS DEVELOPING
AFTER MIDNIGHT AND INTO MONDAY AS HIGH PRESSURE BUILDS IN.
COMPLEX FIRST SIX HOURS TO THE TAF FORECASTS WITH THE MAIN ISSUE
FOCUSED ON PRECIP TYPE AND ATTEMPTING TO TIME THE MIXING/
CHANGEOVER AT EACH SITE. SECONDARY SURFACE WAVE TRACKING INTO
SOUTHERN KENTUCKY WITH A LARGE PRECIP SHIELD EXPANDING BACK INTO
CENTRAL INDIANA FROM THE SOUTH. NEAR SURFACE SUBFREEZING TEMPS
ARE SLOWLY OVERSPREADING THE WABASH VALLEY EARLY THIS AFTERNOON
WHILE MUCH OF THE BOUNDARY LAYER REMAINS ABOVE FREEZING. THIS IS
WHERE THE CHALLENGE COMES IN FOR THE AFTERNOON AS NEAR SURFACE AIR
WILL COOL FASTER THAN THE BOUNDARY LAYER AS IT EXPANDS EAST ACROSS
THE FORECAST AREA. WITH THAT BEING SAID...THE TRACK AND PASSAGE OF
THE SURFACE WAVE JUST SOUTHEAST OF THE REGION OVER THE NEXT FEW
HOURS IS LIKELY TO SLOW EASTWARD ADVECTION OF COLDER AIR SOMEWHAT.
AT THIS POINT...SURFACE TEMPS AT OR JUST BELOW FREEZING AT KHUF
AND KLAF BOTH SUPPORT A FREEZING RAIN AND SLEET MIX TO BEGIN. AS
BOUNDARY LAYER AIR COOLS AND MOISTURE DEEPENS...PRECIP TYPE SHOULD
SHIFT MORE TO SLEET WITH SNOWFLAKES BEGINNING TO MIX IN BY 21Z. AT
KBMG AND KIND...TEMP PROFILES AND MODEL SOUNDINGS POINT TO
PRECIPITATION FALLING PREDOMINANTLY AS RAIN THROUGH 21Z. SLEET MAY
OCCASIONALLY MIX IN PRIOR TO THIS TIME AT BOTH SITES...BUT
POTENTIAL LOOKS LOW ENOUGH TO KEEP OUT OF THE TERMINALS. NEAR
SURFACE AIR SHOULD COOL ENOUGH AT KBMG AND KIND AFTER 21Z FOR
SLEET AND EVENTUALLY SNOW TO BECOME THE MAIN PRECIP TYPE AT BOTH
SITES. PRECIPITATION WILL END ABRUPTLY AT ALL SITES BETWEEN 00Z
AND 02Z AS THE SURFACE WAVE MOVES AWAY TO THE EAST. IFR AND LOWER
CONDITIONS WILL PERSIST ALL AFTERNOON AND INTO THE EVENING...WITH
IMPROVEMENTS TO MVFR LIKELY ONCE PRECIPITATION ENDS. NORTH-NORTHWEST
WINDS WILL BE SUSTAINED AT 10-15KTS THROUGH THE EVENING...WITH
OCCASIONAL GUSTS NEAR 20KTS.
HIGH PRESSURE WILL EXPAND INTO THE OHIO VALLEY OVERNIGHT WITH
DRIER AIR AND BROAD SUBSIDENCE ENABLING SKIES TO EVENTUALLY CLEAR.
PRESENCE OF A SHALLOW LAYER OF LOW LEVEL MOISTURE MAY SERVE TO
KEEP SCATTERED MVFR CEILINGS THROUGH DAYBREAK...BUT OVERALL TREND
WILL BE TOWARDS SKIES BECOMING MAINLY CLEAR. WINDS WILL VEER TO
NORTHERLY MONDAY MORNING AND DECREASE TO 5-10KTS.
&&
.IND WATCHES/WARNINGS/ADVISORIES...
FLOOD WATCH UNTIL 4 PM EST THIS AFTERNOON FOR INZ030-031-036>042-
044>049-051>057-060>065-067>072.
&&
$$
SYNOPSIS...MK
NEAR TERM...CP
SHORT TERM...MK
LONG TERM....RYAN
AVIATION...RYAN
AREA FORECAST DISCUSSION
NWS INDIANAPOLIS IN
1218 PM EST SUN JAN 13 2013
.UPDATE...
THE AVIATION SECTION HAS BEEN UPDATED BELOW.
&&
.SYNOPSIS...
ISSUED AT 326 AM EST SUN JAN 13 2013
COLD FRONT WILL SLOWLY SETTLE SOUTHEAST OF CENTRAL INDIANA TODAY
RESULTING IN THE END OF PRECIPITATION AFTER MIDNIGHT SUNDAY NIGHT
BUT NOT BEFORE HEAVY RAIN CHANGES OVER TO A WINTRY MIX FROM
NORTHWEST TO SOUTHEAST WITH MINOR ICE OR SNOW ACCUMULATION POSSIBLE.
MUCH COLDER MORE SEASONABLE AIR WILL FILTER IN ALONG WITH DRY
WEATHER THROUGH NEXT WEEKEND. THIS WILL ALLOW RIVER FLOODING TO RUN
ITS COURSE.
&&
.NEAR TERM /REST OF TODAY/...
ISSUED AT 1049 AM EST SUN JAN 13 2013
RADAR MOSAIC AND OBSERVATIONS SHOW RAIN STILL FALLING OVER
SOUTHEASTERN FORECAST AREA WITH AREAS OF DRIZZLE OR VERY LIGHT
RAIN OVER THE REST OF THE AREA. AT 11 AM TEMPERATURES RANGED FROM
THE MID 40S IN THE SOUTHEAST TO RIGHT JUST BELOW THE FREEZING MARK
IN THE NORTHWEST. THE COLD FRONT HAS STALLED JUST SOUTH OF THE
AREA AND A SURFACE WAVE IS MOVING ALONG IT INTO THE AREA. THIS
WAVE IS KEEPING THE SUB-FREEZING AIR FROM ADVANCING INTO THE AREA.
FORECAST SOUNDINGS FROM THE RAPID REFRESH AND RAP AS WELL AS THE
NAM SHOW AN INTRUSION OF COLD AIR JUST ABOVE THE SURFACE FROM THE
NORTHWEST WITH A WARM LAYER ABOVE IT AND LOOKS LIKE IT COULD ALLOW
RAIN TO CHANGE OVER OR MIX WITH SLEET IN THE NORTHWEST OVER THE
NEXT COUPLE OF HOURS AND SPREADING SOUTHEAST FROM THERE. SNOW
COULD MIX IN AFTER 1 IN THE NORTHWEST BUT CHANGE OVER TO JUST SNOW
DOESN/T APPEAR LIKELY IN THE NORTHWEST UNTIL AFTER 4 PM. SURFACE
TEMPERATURES HOLDING FAIRLY STEADY OR JUST FALLING SLOWLY OVER THE
NEXT SEVERAL HOURS SO DO NOT SEE A WIDESPREAD RISK FOR FREEZING
RAIN. THE WESTERN COUNTIES WILL SEE THE GREATEST RISK FOR ANY KIND
OF FREEZING RAIN OR FREEZING DRIZZLE BUT STILL DO NOT EXPECT MUCH
IN THE WAY OF ANY ACCUMULATION OF ICE. SOUTHEASTERN COUNTIES CAN
JUST EXPECT RAIN TO INCREASE IN INTENSITY AND COVERAGE THROUGH THE
AFTERNOON AS THE SURFACE WAVE MOVES NORTHEAST ALONG THE FRONT.
WILL CONTINUE WITH THE FLOOD WATCH AS ADDITIONAL HEAVY RAIN COULD
EXACERBATE CURRENT FLOODING SITUATION ACROSS THE AREA...BUT NOT
ANTICIPATING MORE THAN UP TO AN ADDITIONAL HALF INCH IN THE
SOUTHEAST WITH PERHAPS A QUARTER INCH OR LESS NORTH OF I 70.
CHANGE OVER TO SNOW LOOKS FAIRLY LATE...PROBABLY NOT UNTIL THE
TONIGHT PERIOD IN THE CENTRAL AND SOUTH...AND IS FOLLOWED QUICKLY
BY ARRIVAL OF DRY AIR SO DO NOT EXPECT MUCH IN THE WAY OF
ACCUMULATION. COULD SEE LIGHT ACCUMULATIONS OF SLEET IN THE WEST.
&&
.SHORT TERM /MONDAY THROUGH TUESDAY NIGHT/...
ISSUED AT 326 AM EST SUN JAN 13 2013
THE SHORT TERM FOCUS WILL BE MAINLY ON TEMPERATURES AS A VERY DRY
COLUMN WILL BE IN PLACE THROUGH THE PERIOD AS PLAINS HIGH PRESSURE
BUILDS IN ACROSS THE OHIO VALLEY AND LOWER GREAT LAKES RESULTING IN
LITTLE CLOUD COVER AND SLIGHTLY BELOW AVERAGE TEMPERATURES.
OVERALL...00Z MOS NUMBERS LOOK OK. THE ONLY CAVEAT IS THE NAM MOS
LOOKS SEVERAL DEGREES TOO WARM AT BMG BASED ON ITS OTHER FORECASTED
NUMBERS AND THE GFS MOS. ALLBLEND IS A GOOD PROXY. LOOK FOR
AFTERNOON HIGHS IN THE UPPER 20S TO THE MID 30S ON MONDAY AND IN THE
30S ON TUESDAY. OVERNIGHT LOWS WILL BE IN THE UPPER TEENS TO THE
LOWER 20S.
&&
.LONG TERM /WEDNESDAY THROUGH SUNDAY/...
ISSUED AT 329 AM EST SUN JAN 13 2013
A DRY EXTENDED PERIOD IS STILL EXPECTED FOR CENTRAL INDIANA
DESPITE A FEW DISTURBANCES IN THE MEAN FLOW ON WEDNESDAY AND
FRIDAY. THE EURO IS NOW IN LINE WITH THE GFS IN REGARD TO SOME
PRECIP ACROSS NORTHERN INDIANA ON WEDNESDAY...BUT LATEST
INITIALIZATION KEEPS THE FORECAST DRY AND THIS LOOKS GOOD SINCE
PRECIP WILL STAY NORTH OF FORECAST AREA. ANOTHER LOW WILL PASS
OVER THE GREAT LAKES REGION AT THE END OF THE WEEK...BUT ALL
PRECIP WILL STAY WELL NORTH OF CENTRAL INDIANA WITH THIS
DISTURBANCE AS WELL. TEMPS WILL BE CLOSE TO NORMAL...BUT A MUCH
MORE FRIGID AIRMASS IS PROGGED FOR THE REGION BEYOND THE LONG
TERM PERIOD.
&&
.AVIATION /DISCUSSION FOR 131800Z TAF ISSUANCE/...
ISSUED AT 1218 PM EST SUN JAN 13 2013
VERY POOR FLYING CONDITIONS WILL CONTINUE THROUGHOUT THE AFTERNOON
AND EARLY EVENING AS PRECIPITATION SLOWLY MIXES WITH AND CHANGES
OVER TO PREDOMINANTLY SLEET AND SNOW. VFR CONDITIONS DEVELOPING
AFTER MIDNIGHT AND INTO MONDAY AS HIGH PRESSURE BUILDS IN.
COMPLEX FIRST SIX HOURS TO THE TAF FORECASTS WITH THE MAIN ISSUE
FOCUSED ON PRECIP TYPE AND ATTEMPTING TO TIME THE MIXING/
CHANGEOVER AT EACH SITE. SECONDARY SURFACE WAVE TRACKING INTO
SOUTHERN KENTUCKY WITH A LARGE PRECIP SHIELD EXPANDING BACK INTO
CENTRAL INDIANA FROM THE SOUTH. NEAR SURFACE SUBFREEZING TEMPS
ARE SLOWLY OVERSPREADING THE WABASH VALLEY EARLY THIS AFTERNOON
WHILE MUCH OF THE BOUNDARY LAYER REMAINS ABOVE FREEZING. THIS IS
WHERE THE CHALLENGE COMES IN FOR THE AFTERNOON AS NEAR SURFACE AIR
WILL COOL FASTER THAN THE BOUNDARY LAYER AS IT EXPANDS EAST ACROSS
THE FORECAST AREA. WITH THAT BEING SAID...THE TRACK AND PASSAGE OF
THE SURFACE WAVE JUST SOUTHEAST OF THE REGION OVER THE NEXT FEW
HOURS IS LIKELY TO SLOW EASTWARD ADVECTION OF COLDER AIR SOMEWHAT.
AT THIS POINT...SURFACE TEMPS AT OR JUST BELOW FREEZING AT KHUF
AND KLAF BOTH SUPPORT A FREEZING RAIN AND SLEET MIX TO BEGIN. AS
BOUNDARY LAYER AIR COOLS AND MOISTURE DEEPENS...PRECIP TYPE SHOULD
SHIFT MORE TO SLEET WITH SNOWFLAKES BEGINNING TO MIX IN BY 21Z. AT
KBMG AND KIND...TEMP PROFILES AND MODEL SOUNDINGS POINT TO
PRECIPITATION FALLING PREDOMINANTLY AS RAIN THROUGH 21Z. SLEET MAY
OCCASIONALLY MIX IN PRIOR TO THIS TIME AT BOTH SITES...BUT
POTENTIAL LOOKS LOW ENOUGH TO KEEP OUT OF THE TERMINALS. NEAR
SURFACE AIR SHOULD COOL ENOUGH AT KBMG AND KIND AFTER 21Z FOR
SLEET AND EVENTUALLY SNOW TO BECOME THE MAIN PRECIP TYPE AT BOTH
SITES. PRECIPITATION WILL END ABRUPTLY AT ALL SITES BETWEEN 00Z
AND 02Z AS THE SURFACE WAVE MOVES AWAY TO THE EAST. IFR AND LOWER
CONDITIONS WILL PERSIST ALL AFTERNOON AND INTO THE EVENING...WITH
IMPROVEMENTS TO MVFR LIKELY ONCE PRECIPITATION ENDS. NORTH-NORTHWEST
WINDS WILL BE SUSTAINED AT 10-15KTS THROUGH THE EVENING...WITH
OCCASIONAL GUSTS NEAR 20KTS.
HIGH PRESSURE WILL EXPAND INTO THE OHIO VALLEY OVERNIGHT WITH
DRIER AIR AND BROAD SUBSIDENCE ENABLING SKIES TO EVENTUALLY CLEAR.
PRESENCE OF A SHALLOW LAYER OF LOW LEVEL MOISTURE MAY SERVE TO
KEEP SCATTERED MVFR CEILINGS THROUGH DAYBREAK...BUT OVERALL TREND
WILL BE TOWARDS SKIES BECOMING MAINLY CLEAR. WINDS WILL VEER TO
NORTHERLY MONDAY MORNING AND DECREASE TO 5-10KTS.
&&
.IND WATCHES/WARNINGS/ADVISORIES...
FLOOD WATCH UNTIL 4 PM EST THIS AFTERNOON FOR INZ030-031-036>042-
044>049-051>057-060>065-067>072.
&&
$$
SYNOPSIS...MK
NEAR TERM...CP
SHORT TERM...MK
LONG TERM....TDUD
AVIATION...RYAN
AREA FORECAST DISCUSSION
NWS INDIANAPOLIS IN
1109 AM EST SUN JAN 13 2013
.UPDATE...
THE NEAR TERM SECTION HAS BEEN UPDATED BELOW
&&
.SYNOPSIS...
ISSUED AT 326 AM EST SUN JAN 13 2013
COLD FRONT WILL SLOWLY SETTLE SOUTHEAST OF CENTRAL INDIANA TODAY
RESULTING IN THE END OF PRECIPITATION AFTER MIDNIGHT SUNDAY NIGHT
BUT NOT BEFORE HEAVY RAIN CHANGES OVER TO A WINTRY MIX FROM
NORTHWEST TO SOUTHEAST WITH MINOR ICE OR SNOW ACCUMULATION POSSIBLE.
MUCH COLDER MORE SEASONABLE AIR WILL FILTER IN ALONG WITH DRY
WEATHER THROUGH NEXT WEEKEND. THIS WILL ALLOW RIVER FLOODING TO RUN
ITS COURSE.
&&
.NEAR TERM /REST OF TODAY/...
ISSUED AT 1049 AM EST SUN JAN 13 2013
RADAR MOSAIC AND OBSERVATIONS SHOW RAIN STILL FALLING OVER
SOUTHEASTERN FORECAST AREA WITH AREAS OF DRIZZLE OR VERY LIGHT
RAIN OVER THE REST OF THE AREA. AT 11 AM TEMPERATURES RANGED FROM
THE MID 40S IN THE SOUTHEAST TO RIGHT JUST BELOW THE FREEZING MARK
IN THE NORTHWEST. THE COLD FRONT HAS STALLED JUST SOUTH OF THE
AREA AND A SURFACE WAVE IS MOVING ALONG IT INTO THE AREA. THIS
WAVE IS KEEPING THE SUB-FREEZING AIR FROM ADVANCING INTO THE AREA.
FORECAST SOUNDINGS FROM THE RAPID REFRESH AND RAP AS WELL AS THE
NAM SHOW AN INTRUSION OF COLD AIR JUST ABOVE THE SURFACE FROM THE
NORTHWEST WITH A WARM LAYER ABOVE IT AND LOOKS LIKE IT COULD ALLOW
RAIN TO CHANGE OVER OR MIX WITH SLEET IN THE NORTHWEST OVER THE
NEXT COUPLE OF HOURS AND SPREADING SOUTHEAST FROM THERE. SNOW
COULD MIX IN AFTER 1 IN THE NORTHWEST BUT CHANGE OVER TO JUST SNOW
DOESN/T APPEAR LIKELY IN THE NORTHWEST UNTIL AFTER 4 PM. SURFACE
TEMPERATURES HOLDING FAIRLY STEADY OR JUST FALLING SLOWLY OVER THE
NEXT SEVERAL HOURS SO DO NOT SEE A WIDESPREAD RISK FOR FREEZING
RAIN. THE WESTERN COUNTIES WILL SEE THE GREATEST RISK FOR ANY KIND
OF FREEZING RAIN OR FREEZING DRIZZLE BUT STILL DO NOT EXPECT MUCH
IN THE WAY OF ANY ACCUMULATION OF ICE. SOUTHEASTERN COUNTIES CAN
JUST EXPECT RAIN TO INCREASE IN INTENSITY AND COVERAGE THROUGH THE
AFTERNOON AS THE SURFACE WAVE MOVES NORTHEAST ALONG THE FRONT.
WILL CONTINUE WITH THE FLOOD WATCH AS ADDITIONAL HEAVY RAIN COULD
EXACERBATE CURRENT FLOODING SITUATION ACROSS THE AREA...BUT NOT
ANTICIPATING MORE THAN UP TO AN ADDITIONAL HALF INCH IN THE
SOUTHEAST WITH PERHAPS A QUARTER INCH OR LESS NORTH OF I 70.
CHANGE OVER TO SNOW LOOKS FAIRLY LATE...PROBABLY NOT UNTIL THE
TONIGHT PERIOD IN THE CENTRAL AND SOUTH...AND IS FOLLOWED QUICKLY
BY ARRIVAL OF DRY AIR SO DO NOT EXPECT MUCH IN THE WAY OF
ACCUMULATION. COULD SEE LIGHT ACCUMULATIONS OF SLEET IN THE WEST.
&&
.SHORT TERM /MONDAY THROUGH TUESDAY NIGHT/...
ISSUED AT 326 AM EST SUN JAN 13 2013
THE SHORT TERM FOCUS WILL BE MAINLY ON TEMPERATURES AS A VERY DRY
COLUMN WILL BE IN PLACE THROUGH THE PERIOD AS PLAINS HIGH PRESSURE
BUILDS IN ACROSS THE OHIO VALLEY AND LOWER GREAT LAKES RESULTING IN
LITTLE CLOUD COVER AND SLIGHTLY BELOW AVERAGE TEMPERATURES.
OVERALL...00Z MOS NUMBERS LOOK OK. THE ONLY CAVEAT IS THE NAM MOS
LOOKS SEVERAL DEGREES TOO WARM AT BMG BASED ON ITS OTHER FORECASTED
NUMBERS AND THE GFS MOS. ALLBLEND IS A GOOD PROXY. LOOK FOR
AFTERNOON HIGHS IN THE UPPER 20S TO THE MID 30S ON MONDAY AND IN THE
30S ON TUESDAY. OVERNIGHT LOWS WILL BE IN THE UPPER TEENS TO THE
LOWER 20S.
&&
.LONG TERM /WEDNESDAY THROUGH SUNDAY/...
ISSUED AT 329 AM EST SUN JAN 13 2013
A DRY EXTENDED PERIOD IS STILL EXPECTED FOR CENTRAL INDIANA
DESPITE A FEW DISTURBANCES IN THE MEAN FLOW ON WEDNESDAY AND
FRIDAY. THE EURO IS NOW IN LINE WITH THE GFS IN REGARD TO SOME
PRECIP ACROSS NORTHERN INDIANA ON WEDNESDAY...BUT LATEST
INITIALIZATION KEEPS THE FORECAST DRY AND THIS LOOKS GOOD SINCE
PRECIP WILL STAY NORTH OF FORECAST AREA. ANOTHER LOW WILL PASS
OVER THE GREAT LAKES REGION AT THE END OF THE WEEK...BUT ALL
PRECIP WILL STAY WELL NORTH OF CENTRAL INDIANA WITH THIS
DISTURBANCE AS WELL. TEMPS WILL BE CLOSE TO NORMAL...BUT A MUCH
MORE FRIGID AIRMASS IS PROGGED FOR THE REGION BEYOND THE LONG
TERM PERIOD.
&&
.AVIATION /DISCUSSION FOR THE 131500Z TAF ISSUANCE/...
ISSUED AT 941 AM EST SUN JAN 13 2013
STEADIEST RAINFALL HAS MOVED EAST OF ALL OF THE TERMINALS AND AS
EXPECTED WITH A POCKET OF SLIGHTLY DRIER AIR ALOFT TRAVERSING THE
REGION...PRECIP HAS LIGHTENED CONSIDERABLY TO DRIZZLE OR VERY LIGHT
RAIN. THIS SHOULD CONTINUE FOR THE NEXT FEW HOURS WITH IFR AND LOWER
CONDITIONS AT ALL TERMINALS. SECONDARY SURFACE WAVE LIFTING THROUGH
THE TENNESSEE VALLEY WILL BRING STEADIER PRECIP BACK INTO THE
FORECAST AREA BY EARLY AFTERNOON. MOST RECENT SHORT RANGE GUIDANCE
INDICATING COLDER AIR MAY BE SLIGHTLY DELAYED IN ITS EXPANSION INTO
THE FORECAST AREA THIS AFTERNOON AND HAVE SLOWED THE CHANGEOVER TO
SLEET AND EVENTUALLY SNOW AT ALL SITES BY AN HOUR OR TWO. KLAF WILL
BE IMPACTED FIRST BY 16-17Z WITH THE OTHER THREE SITES SEEING MIXING
BEGIN BETWEEN 18-21Z FROM WEST TO EAST. CEILINGS WILL REMAIN LOWER
THAN 1000FT INTO THE EVENING.
12Z DISCUSSION FOLLOWS.
POOR FLYING CONDITIONS WILL PERSIST FOR MOST OF TAF PERIOD AS
WIDESPREAD RAINFALL COVERS MOST OF CENTRAL INDIANA. ANTICIPATE IFR
CONDITIONS THROUGH SUN 00Z AND THEN QUICK IMPROVEMENT TO MVFR
CATEGORY THIS EVENING...AND FINALLY VFR AFTER MON 06Z.
CURRENTLY...THE COLD FRONT ASSOCIATED WITH THE PRECIP IS SOUTHEAST
OF ALL TAF SITES. PRECIP HAS ENDED FOR THE MOMENT AT KLAF AND
KHUF...BUT IT SHOULD COMMENCE AGAIN BY LATE MORNING AS ANOTHER
WAVE RIDES ALONG THAT COLD FRONT. MEANWHILE...LIGHT RAIN/DRIZZLE
WILL CONTINUE TO PERSIST AT KIND AND KBMG.
BY THE TIME PRECIP STARTS UP AGAIN...COLDER AIR WILL BE IN PLACE AT
KLAF AND KHUF...AND THE TRANSITION TO WINTRY MIX WILL BEGIN. THE
COLDER AIR WILL WORK ITS WAY INTO KIND AND KBMG BY MID AFTERNOON.
PRECIP WILL TRANSITION FROM FREEZING RAIN/SLEET MIX TO SNOW.
WINDS WILL BE NORTHWESTERLY AT 10 TO 12 KTS WITH GUSTS UP TO 22
KTS AT TIMES.
&&
.IND WATCHES/WARNINGS/ADVISORIES...
FLOOD WATCH UNTIL 4 PM EST THIS AFTERNOON FOR INZ030-031-036>042-
044>049-051>057-060>065-067>072.
&&
$$
SYNOPSIS...MK
NEAR TERM...CP
SHORT TERM...MK
LONG TERM....TDUD
AVIATION...TDUD/RYAN
AREA FORECAST DISCUSSION
NWS QUAD CITIES IA IL
1141 PM CST SAT JAN 12 2013
.AVIATION...
SNOW CONTINUES TO AFFECT THE AREA...AND IS EXPECTED TO BEGIN
TAPERING OFF FROM SOUTHWEST TO NORTHEAST IN THE NEXT FEW HOURS.
KCID AND KDBQ ARE LIKELY TO SEE ANOTHER 2-4 HOURS OF LIGHT SNOW
WITH MVFR CONDITIONS. KMLI AND KBRL SHOULD SEE ANOTHER 1-2 HOURS
OF IFR VSBYS AND MVFR CIGS IN LIGHT SNOW BEFORE ALSO SWITCHING TO
MAINLY MVFR CIGS AND VSBYS WITH LIGHTER SNOW. ALL FOUR SITES SHOULD
BE BACK TO VFR BY 11Z. AN AREA OF MVFR STRATUS MAY SWING INTO THE
TERMINALS AFTER 15Z SUNDAY...WHICH SHOULD RISE INTO VFR DURING THE
EARLY AFTERNOON. CLOUDS SHOULD CLEAR OUT OF THE TERMINALS AFTER
00Z TONIGHT...BUT AS WE WILL ALREADY BE VFR NO CHANGE GROUP HAS
BEEN INCLUDED.
LE
&&
.PREV DISCUSSION... /ISSUED 933 PM CST SAT JAN 12 2013/
UPDATE...
NOW THAT WE ARE GETTING NUMEROUS REPORTS OF SNOW AND SLEET
BEGINNING ACROSS THE FORECAST AREA...A BETTER SPECIFICATION CAN BE
MADE AS TO WHERE THE SNOW/SLEET LINE CAN BE MADE. EXPECT THAT
LOCATIONS AROUND MACOMB...AND ALSO AROUND PRINCETON ARE GETTING A
WINTERY MIXTURE OF SLEET AND POSSIBLY EVEN FREEZING RAIN AS WELL.
THIS MIXTURE MAY ALSO AFFECT KEWANEE AND PORTIONS OF HENRY COUNTY...AND
EASTERN WARREN COUNTIES AS WELL IN THE NEXT FEW HOURS. WSR-88D
DUAL POL DATA IS SHOWING AREAS WHERE SLEET IS EXPECTED QUITE
NICELY THIS EVENING. HAVE MADE SOME ADJUSTMENTS TO THE FORECAST TO
REFLECT THE CURRENT TRENDS...BUT HAVE KEPT SNOWFALL AMOUNTS ABOUT
THE SAME AS BEFORE. IF THE SLEET CONTINUES FOR TOO LONG IN THE
SOUTHEAST...THE SNOWFALL FORECAST MAY NEED TO BE REDUCED IN THOSE
AREAS.
PREV DISCUSSION... /ISSUED 303 PM CST SAT JAN 12 2013/
SYNOPSIS...
COLD FRONT PUSHING INTO THE OHIO VALLEY THIS AFTERNOON...WITH COLD
AIR OOZING INTO THE UPPER MISSISSIPPI VALLEY BEHIND IT. LONG WAVE
TROUGH SPANNING THE ROCKIES...WITH ENERGY LIFTING OUT OVER THE
CENTRAL US IN FAST SOUTHWEST FLOW. LEAD SHORTWAVE GENERATING SOME
SNOW/SLEET OVER NORTHERN MO AND INTO SE IA AT THIS TIME. MAIN
PRECIP AREA ACROSS SOUTHERN MO AND SOUTHERN ILLINOIS IS ALSO
EXPANDING NORTHWARD AND IS NOW PUSHING INTO CENTRAL ILLINOIS AHEAD
OF THE MAIN SHORT WAVE...WHICH CAN BE SEEN ON SATELLITE LIFTING OUT
OF ARKANSAS.
SHORT TERM...TONIGHT AND SUNDAY...
MAIN FORECAST QUESTIONS THIS AFTERNOON CENTER AROUND DEVELOPING
PRECIPITATION EVENT FOR TONIGHT. THE INITIAL WAVE OF LIGHT SNOW/SLEET
NOW MOVING ACROSS EASTERN IA WILL HELP COOL AND SATURATE THE COLUMN
AHEAD OF TONIGHTS WAVE BUT WILL HAVE LITTLE OTHER IMPACT. FOR TONIGHT...OF
THE SHORT RANGE MODELS...THE RAP IS THE MOST AGGRESSIVE WITH
SNOWFALL AMOUNTS...SUGGESTING 4 TO 6 INCHES ALONG AND EAST OF THE
MISSISSIPPI RIVER. MEANWHILE...THE NAM...GFS...AND ECMWF ARE MORE
CONSERVATIVE WITH 2-3 INCHES AT MOST. THUS WILL FAVOR A BLEND OF
THE NAM AND ECMWF FOR THIS FORECAST...ESPECIALLY FOR MOISTURE PARAMETERS.
THERE IS CONSISTENCY IN THE FORECAST SOUNDINGS...SHOWING A LARGE
WEDGE OF WARM AIR ALOFT...ESPECIALLY EAST OF THE MISSISSIPPI
RIVER...THAT WILL HAVE TO COOL BEFORE PRECIP CHANGES TO SNOW.
CURRENT THINKING IS THAT NEAR THE RIVER THE PERIOD OF SLEET SHOULD
BE BRIEF...BUT WILL LAST LONGER AS YOU GO EAST. BUREAU/PUTNAM
COUNTIES COULD SEE A COUPLE OF HOURS OF SLEET BEFORE IT CHANGES TO
SNOW BY MIDNIGHT. IT IS ALSO NOT OUT OF THE QUESTION FOR A BRIEF
PERIOD OF FREEZING RAIN TO FALL AT ONSET IN THE BUREAU/PUTNAM
COUNTY AREA. HOWEVER...IF THIS WOULD OCCUR...THE EVAPORATIVE
COOLING WOULD QUICKLY CHANGE IT TO SLEET. AND WITH THE WARM
TEMPERATURES THESE LAST FEW DAYS...ONLY ELEVATED SURFACES SHOULD
BE AT RISK FOR FREEZING.
IN TERMS OF SNOW AMOUNTS...THE GARCIA METHOD WOULD SUGGEST 2-4 INCHES
IN THE HEAVIEST BAND FROM THE QUAD CITIES NORTHEASTWARD. THE MODEL TIME
SECTIONS DO SUPPORT THIS...SHOWING POTENTIAL FOR DENDRITIC GROWTH
IN THAT SAME AREA. WHILE DENDRITES WOULD INCREASE AMOUNTS...THE SHORT
DURATION OF THE EVENT AND ANY SLEET AT ONSET WILL LIMIT THE
ACCUMULATIONS.
THE BOTTOM LINE IS THAT I EXPECT A SHARP CUT-OFF IN SNOW ACCUMULATIONS
SOMEWHERE IN THE VICINITY OF THE 380 CORRIDOR...THE HEAVIEST SNOW
AMOUNTS IN THE 2-4 INCH RANGE FROM NEAR THE QUAD CITIES NORTHEASTWARD
TO FREEPORT...AND A LONGER PERIOD OF SLEET WITH LESSER SNOW
ACCUMULATIONS AS YOU MOVE TOWARD THE PRINCETON ILLINOIS AREA. THE
MAIN PRECIP EVENT WILL BEGIN AFTER 6 PM TONIGHT...CHANGING TO SNOW
AREA WIDE BY MIDNIGHT AND SHOULD HAVE EXITED ALL BUT THE EXTREME
EASTERN PORTIONS OF THE CWFA BY 6 AM.
DMD
LONG TERM...SUNDAY NIGHT THROUGH NEXT SATURDAY...
SUNDAY NIGHT AND MONDAY...LATEST 12Z RUN MODELS IN GOOD AGREEMENT OF
SUGGESTING SFC RIDGING SLIDING ACRS THE REGION FROM THE WEST SUNDAY
NIGHT...WHILE CONFLUENT FLOW REGION WEST OF L/W TROF TRYING TO
PHASE ACRS THE EASTERN ROCKIES. EXPECT CLEARING SKIES AS HIGH CLOUDS
NORTHWEST OF LLVL BAROCLINIC REGION PUSH EASTWARD...COMBINED WITH
DECREASING WINDS FOR A COLD NIGHT OVER FRESH SNOW COVER. SOME SINGLE
DIGITS POSSIBLE BY EARLY MON MORNING. MAINLY CLEAR SKIES AND COLD
CONDITIONS TO FINISH OUT THE PERIOD WITH HIGHS IN THE 20S MON AND
SINGLE DIGITS TO LOWER TEENS MON NIGHT. SOME LIGHT RETURN FLOW MAY
MAKE FOR NON-DIURNAL TEMP TRENDS PRE-DAWN EARLY TUE MORNING WEST OF
THE MS RVR.
TUESDAY AND WEDNESDAY...LATEST RUN MEDIUM RANGE SOLUTIONS SUGGEST
THE ABOVE MENTIONED LONG WAVE TROF AXIS WILL SHEAR ACRS THE MID
CONUS THIS PERIOD FROM THE GRT LKS...ALL THE WAY TO THE BAJA OF MEX.
UPPER RIDGE ALONG AND JUST OFF THE WEST COAST AMPLIFIES...EVENTUALLY
DUMPING RIDGE-RIDING WAVE ENERGY DOWN ACRS THE UPPER MIDWEST AND GRT
LKS THROUGH MID WEEK. HOW FAR SOUTH THIS CLIPPER TYPE WAVE WILL
EVENTUALLY DIG IS STILL SOMEWHAT UNCERTAIN...ALL LONGER RANGE MODEL
SOLUTIONS BUT THE 12Z GFS KEEP LEAD WAVE AND IT/S ASSOCIATED PRECIP
TO THE NORTH OF THE AREA UNTIL MAYBE WED NIGHT WHEN SOME FLURRIES
MAKE IT ACRS THE NORTHEASTERN THIRD OF THE AREA/CWA UNDER RE-
ENFORCING CYCLONIC FLOW DIGGING ACRS THE SOUTHWESTERN GRT LKS. THE
12Z GFS IS MORE PROGRESSIVE AND DEEPER SOUTH WITH THE CLIPPER AND
PRODUCES LIGHT SNOW ACRS MOST OF THE LOCAL AREA TUE NIGHT INTO WED
MORNING BEFORE SHUTTLING QUICKLY OFF TO THE EAST. FOR NOW WILL SIDE
WITH THE MAJORITY AND KEEP THE FCST DRY...WITH THERMAL MODERATION
FROM THE SOUTHWEST AHEAD OF THE NORTHERN STREAM CLIPPER. HIGHS TUE
NEAR 30...MAY TRANSLATE INTO THE 30S BY WED BEFORE COLD FRONT OFF
THE PASSING CLIPPER SYSTEM TO THE NORTH SWEEPS THROUGH THE CWA BY
LATE WED.
THURSDAY THROUGH SATURDAY...LATEST RUN MEDIUM RANGE MODEL SOLUTIONS
AND ENSEMBLES GENERALLY SUGGEST WHILE A TYPE OF REX BLOCK SETS UP
ACRS THE WEST COAST AND SOUTHWESTERN U.S...BROAD UPPER LEVEL
TROFFINESS SETS UP ACRS MUCH OF THE EASTERN CONUS SOUTH OF NORTHERN
HUDSON BAY POLAR VORTEX. A RIBBON OF LLVL BAROCLINICITY SETS UP
PARALLEL TO THIS FEATURE FROM SOUTH CENTRAL CANADA...TO THE MID
ATLANTIC WHILE A BUILDING DOME OF VERY COLD AIRMASS LOOMS ACRS THE
EASTERN TWO THIRDS OF CANADA. WHILE THE REAL COLD AIR REMAINS BOTTLED
UP BY THIS PATTERN...WILL CONTINUE TO ADVERTISE MODERATING TEMPS
THROUGH SAT. DRY CONDITIONS TOO AS ANY IMPULSES WILL LOOK TO RIPPLE
ALONG THE BAROCLINIC RIBBON AND PRODUCE PRECIP MAINLY OT THE NORTH
ACRS THE DAKOTAS...MN...WI AND THE NORTH HALF OF THE GRT LKS INTO
SAT NIGHT. SOME LONGER RANGE SIGNS OF PLUNGING JET ENERGY TO ALLOW
SOME OF THE ARCTIC AIR TO BREAK LOOSE AND SPILL ACRS THE WESTERN
GRT LKS BY EARLY NEXT WEEK. ..12..
&&
.DVN WATCHES/WARNINGS/ADVISORIES...
IA...WINTER WEATHER ADVISORY UNTIL 6 AM CST SUNDAY FOR CLINTON-DES
MOINES-JACKSON-LEE-LOUISA-MUSCATINE-SCOTT.
IL...WINTER WEATHER ADVISORY UNTIL 6 AM CST SUNDAY FOR BUREAU-CARROLL-
HANCOCK-HENDERSON-HENRY IL-JO DAVIESS-MCDONOUGH-MERCER-
PUTNAM-ROCK ISLAND-STEPHENSON-WARREN-WHITESIDE.
MO...WINTER WEATHER ADVISORY UNTIL 6 AM CST SUNDAY FOR CLARK.
&&
$$
LE
AREA FORECAST DISCUSSION
NWS GOODLAND KS
431 PM MST MON JAN 14 2013
.SHORT TERM...(THIS AFTERNOON THROUGH TUESDAY)
ISSUED AT 111 PM MST MON JAN 14 2013
CURRENT WV IMAGERY AND RUC H5 ANALYSIS SHOW LARGE TROUGH EXTENDING
FROM CANADA ACROSS THE PLAINS AND SW US TO THE BAJA PENINSULA. MEAN
AXIS IS CURRENTLY UPSTREAM OF CWA ALONG THE CENTRAL ROCKIES WITH
SURFACE TROUGH ALONG FRONT RANGE.
RUC INDICATES AXIS OF H85-H7 FRONTOGENESIS IN PLACE ACROSS EASTERN
COLORADO AND FAR WESTERN KANSAS WHERE LIGHT SNOW HAS BEEN FALLING
FOR MOST OF THE DAY. AS THE UPPER LEVEL TROUGH SHIFTS EAST THIS
EVENING THIS AXIS OF FORCING WILL BEGIN TO WEAKEN AND SHIFT
SOUTH...WITH SNOW COMING TO AN END OVER OUR SW CWA BY 03Z. I
COULD NOT RULE OUT ADDITIONAL SNOW ACCUMULATION AROUND ONE INCH
ALONG AN AXIS FROM STRATTON COLORADO TO BENKELMAN NEBRASKA THROUGH
THIS AFTERNOON WHERE RADAR SHOWS SOME INTENSIFICATION...HOWEVER
MOST LOCATIONS SHOULD SEE LESS THAN ONE HALF INCH TOTAL SNOW
ACCUMULATION FOR THIS EVENT. SUBSIDENCE AND A DRY AIR MASS WILL
BEGIN TO WORK IN OVER THE CWA AFTER MIDNIGHT WITH CLEARING SKIES
FROM THE NORTHWEST OVERNIGHT. THERE WILL BE LITTLE CHANGE IN THE
COLD AIRMASS FROM LAST NIGHT...SO DEPENDING ON HOW QUICKLY
CLOUDS CLEAR WE COULD SEE NEGATIVE TEMPERATURES ONCE AGAIN OVER
PARTS OF THE CWA. FOR NOW I LIMITED COLDEST TEMPS TO THE NORTH AND
WEST WHERE CLOUDS ARE MOST LIKELY TO CLEAR BEFORE SUNRISE.
AIRMASS WILL BEGIN TO MODERATE BY MIDDAY TUESDAY AS LEE TROUGH
DEVELOPS AND WINDS SHIFT TO THE WEST. IT IS A TOUGH CALL ON WHAT
IMPACT LINGERING SNOW PACK WILL HAVE...HOWEVER WE SHOULD SEE
TEMPERATURES IN THE LOW TO MID 30S ACROSS ALL THE CWA...WITH A FEW
LOCATIONS IN THE SOUTH AND EAST POSSIBLY WARMER.
.LONG TERM...(TUESDAY NIGHT THROUGH MONDAY)
ISSUED AT 233 PM MST MON JAN 14 2013
FORECAST PROBLEMS WILL BE AMOUNT OF WARMUP DURING THE EARLY PORTION
OF THIS PERIOD FOLLOWED BY HOW MUCH TO COOL IT DOWN AT THE END OF
THE PERIOD. SATELLITE SHOWING AN AMPLIFIED FLOW STARTING WITH A
BROAD...DEEP AND COMPLICATED UPPER TROUGH OVER THE WESTERN HALF OF
THE PACIFIC WHICH IS MAINTAINING/AMPLIFYING AN UPPER RIDGE NEAR THE
WEST COAST OF NORTH AMERICA. THIS TRANSITIONS TO A TROUGH OVER THE
CENTER OF THE COUNTRY WHICH HAS/CONTINUES TO SPLIT. COLD AIR REMAINS
OVER THE AREA AND UPSTREAM AT THIS TIME.
MODELS INITIALIZED FINE AT JET LEVEL. HOWEVER...THEY WERE A LITTLE
UNDERDONE ON THE SPEEDS BEHIND THE UPPER TROUGH OVER THE COUNTRY.
THE GFS WAS DOING A LITTLE BETTER THAN THE CANADIAN AND NAM. MODELS
INITIALIZED FINE AT MID LEVELS WITH THE ECMWF AND UKMET DOING A
LITTLE BETTER THAN THE GFS AND CANADIAN. THE ECMWF WAS DOING THE
BEST AT THE SURFACE. THE ECMWF WAS DOING A LITTLE BETTER THAN THE
GFS...UKMET AND CANADIAN ON THE LOW LEVEL THERMAL FIELD.
TUESDAY NIGHT/WEDNESDAY...LEFT FRONT QUADRANT OF THE JET MOVES
ACROSS DURING THE NIGHT. UPPER TROUGH WILL HAVE MOVED EAST OF THE
AREA BY THE BEGINNING OF THIS PERIOD. IN ADDITION TO THE LIFT FROM
THE JET...MOISTURE INCREASES THROUGH MID LEVELS ON THE WEST SIDE OF
THE TROUGH. THERE IS SOME MODERATE FRONTOGENESIS AS WELL. LAPSE
RATES ARE NOT THAT GREAT. HOWEVER WITH THE COLD AIR IN PLACE AND THE
MODELS SHOWING DEEP ENOUGH MOISTURE...WILL INSERT FLURRIES INTO
THE NORTHWEST HALF SINCE THE SYNOPTIC LIFT IS NOT THAT GREAT BUT
MESOSCALE FORCING IS PRETTY GOOD. WHATEVER FALLS SHOULD BE DONE BY
06Z.
AFTER THE FLURRIES END...SUBSIDENCE INCREASE BEHIND JET AND UPPER
TROUGH. SO WINDS COULD BECOME BREEZY FROM A DOWNSLOPE DIRECTION FOR
A SHORT PERIOD OF TIME. THIS SHOULD MAKE THE MINS WARMER AND DID
WARM THEM SOME BUT MAYBE NOT ENOUGH. PLENTY OF SUN AND DOWNSLOPE
WINDS SHOULD MAKE FOR A MUCH WARMER DAY THAN WE HAVE BEEN HAVING
LATELY. IN GENERAL...MAXES SHOULD RANGE FROM THE MIDDLE 40S TO NEAR
50 DEGREES.
WEDNESDAY NIGHT/THURSDAY...DOWNSLOPE WINDS SHOULD KEEP MINS WARMER
AGAIN. WILL HAVE PLENTY OF SUN BUT NOT AS FAVORABLE OF A WIND FIELD.
NEW GUIDANCE INDICATES HIGH TEMPERATURES SIMILAR TO WEDNESDAYS AND
DID NOT CHANGE MUCH.
THURSDAY NIGHT THROUGH MONDAY...CURRENT AMPLIFIED PATTERN FLATTENS
OUT A LITTLE BIT EARLY IN THE PERIOD BEFORE BECOMING VERY AMPLIFIED
BY THE END OF THE PERIOD ONCE AGAIN. THROUGH FRIDAY SHOULD MAINTAIN
HIGH TEMPERATURES VERY SIMILAR TO WHAT THEY WERE ON WEDNESDAY AND
THURSDAY. THEN A BIG CHANGE IS GOING TO OCCUR IN TEMPERATURE BUT
WITH UNCERTAINTY IN TIMING AND MAGNITUDE OF THIS TEMPERATURE.
GIVEN WHAT THE PATTERN IS...HAVING A MUCH COLDER AIR MASS INTRUDE
INTO THE REGION IS PRETTY MUCH A GIVEN BUT THE MODELS DISAGREE ON
HOW FAST THEY WHAT TO DO IT. THE GFS AND CANADIAN BRING IN THE
COOLER AIR FASTER WHICH IS FROM LATE SATURDAY AFTERNOON INTO THE
NIGHT. THE 00Z AND 12Z ECMWF PRETTY MUCH KEEP THE COLDER AIR OUT
DURING THE DAY ON SATURDAY. HOWEVER...THE 12Z ECMWF IS MUCH QUICKER
THAN THE OLD RUN IN BRINGING THE COLDER AIR ON SATURDAY NIGHT AND
SUNDAY WHICH A BIG DIFFERENCE ON SUNDAY MAXES. MODELS IN BETTER
AGREEMENT AND MUCH BETTER THAN EARLIER IN BRINGING IN AN ABSOLUTELY
FRIGID AIR MASS SUNDAY NIGHT INTO MONDAY.
THROUGH SATURDAY NIGHT LEFT IN WHAT THE CRH_INIT GAVE ME ALTHOUGH IT
IS POSSIBLE THAT SATURDAY AND SATURDAY NIGHT TEMPERATURES COULD BE
COLDER. FELT PER THE AMPLIFIED PATTERN MAKING THE AREA SUSCEPTIBLE
TO HAVING MUCH COLDER AIR BROUGHT IN...SIGNIFICANT SNOW FIELD OVER
THE NORTH CENTRAL PORTION OF THE COUNTRY...AND MORE MODEL SUPPORT FOR
A SOONER ARRIVING COLD AIR MASS WHICH IS NOT UNCOMMON WITH THIS
MAGNITUDE OF COLD AIR...ADJUSTED THE TEMPERATURES...ESPECIALLY THE
MAXES FOR SUNDAY AND MONDAY...DOWN FROM THE INIT. CONSIDERING THE
AIR MASS WE HAVE HAD IN PLACE FOR THE LAST FEW DAYS AND WHAT THE
MODELS ARE SHOWING...THESE TEMPERATURES WILL PROBABLY NOT BE COLD
ENOUGH...BUT STARTED THE TREND DOWN.
IN REGARDS TO THE PRECIPITATION...LEFT WHAT THE CRH_INIT GAVE ME
WHICH HAS IT DRY DURING THE ENTIRE PERIOD. ALTHOUGH WOULD NOT BE
SURPRISED TO SEE SOME FLURRIES WHEN THE COLD AIR MASS BEGINS TO
ENTER THE AREA.
&&
.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z TUESDAY EVENING)
ISSUED AT 424 PM MST MON JAN 14 2013
CURRENT RADAR INDICATES LIGHT SNOW MOVING AWAY FROM KGLD. KMCK
CIGS ARE INCREASING SO AM DOUBTFUL KMCK WILL HAVE ANY SNOW.
FLURRIES CANNOT BE RULED OUT BUT WILL LEAVE THEM OUT OF THE TAF
DUE TO INCREASING CIGS. CONSEQUENTLY EXECT VFR CONDITIONS
OVERNIGHT. CLOUDS WILL START TO INCREASE TUESDAY AFTERNOON AHEAD
OF THE NEXT SHORTWAVE AND A POSSIBLE SLIGHT CHANCE OF LIGHT SNOW
TUESDAY EVENING.
&&
.GLD WATCHES/WARNINGS/ADVISORIES...
KS...NONE.
CO...NONE.
NE...NONE.
&&
$$
SHORT TERM...DR
LONG TERM...BULLER
AVIATION...FS
AREA FORECAST DISCUSSION
NWS LOUISVILLE KY
1256 PM EST SUN JAN 13 2013
.Forecast Update...
Issued at 1255 PM EST Sun Jan 13 2013
Heavier rains across portions of east central Kentucky and parts of
central Kentucky overnight have resulted in lower flash flood
guidance. With rains ongoing and heavier rains with embedded
thunderstorms moving into the area, have gone ahead and expanded the
Flood Watch east. Small rivers may quickly rise to near flood stage
this afternoon and minor areal flooding will be possible with the
heaviest rain. Updates are already out.
Issued at 940 AM EST Sun Jan 13 2013
The first heavier wave of precipitation has pushed to the east this
morning with mostly light rain across much of the forecast area.
Southwest portions of central Kentucky are most likely seeing some
moderate rain at this time. The highest rainfall report we have
received for the last 24 hours is a bit over 2 inches, though
portions of Dubois county have likely seen higher amounts.
Though the rain has begun to move out of southern Indiana, it looks
to increase again this afternoon. Another wave of rain is moving
across Arkansas. The latest runs of the rapid refresh and HRRR show
this area moving across the northwestern portions of the forecast
area. Additionally, some heavier rain showers look to continue to
move out of central TN into could central Kentucky. All told, much
of the region may see an additional one to possibly two inches of
rain today. Though not much areal flooding has been reported yet, it
will still be possible this afternoon as rains move once again
across saturated grounds.
Have adjusted the forecast based on current trends. In addition,
temperatures behind the front are falling faster than the previous
forecast, so did some adjustments to the hourly temps as well.
Updates are already out.
&&
.Short Term (Today through Monday)...
Issued at 330 AM EST Sun Jan 13 2013
...Flood Watch in Effect through Sunday Evening for areas along and
west of I-65...
Several disturbances ejecting out of strong southwest flow along a
slow-moving baroclinic zone will be the main story this short term
period. Heavy rain, strong winds, and even some wintry
precipitation on the backside all look in play over the next 36
hours.
The synoptic boundary is currently draped from western Ohio
southwest through southern Indiana and western Kentucky. As waves
ride along this boundary, convergence is enhanced and there have
been several rounds of strong, to occasionally severe thunderstorms
as storms accelerate along the mesoscale cold front. Radar has
shown a weakening trend over the last hour or so, and expect that to
be the general rule through early this morning. However, with 40-50
knots just off the surface, the stronger showers and isolated
thunderstorms will be able to pull down higher momentum air,
resulting in gusts up to 50 MPH.
The strong thunderstorm threat should continue to wane through the
morning hours as storms outrun the better instability. Then the
attention turns to the heavy rain potential. The 13/00Z NAM has a
pretty good handle on current trends, albeit a bit slow with the
precipitation. Thus, have leaned on it for the short term forecast,
but bringing things in a bit quicker. PWATs have risen to near 1.5
inches overnight (00Z OHX sounding came in with 1.29) and warm cloud
depths will remain at 10-12 thousand feet today. Copious moisture
transport on the nose of a low-level jet will feed into the
slow-moving boundary, producing moderate to locally heavy rainfall.
In addition, latest guidance continues to advertise another synoptic
shortwave lifting northeast along the boundary late this morning
into early this afternoon. This will help enhance precipitation
rates, especially across south central Kentucky generally west of
I-65. Think that 2 to 3 inches is possible there, with locally
higher amounts. Elsewhere, generally 1-2 inches is likely as the
front slowly progresses east.
In addition to the heavy rain potential, another added element to
this system is the chance for wintry precipitation as the front
exits. However, latest guidance continues to speed up the
progression of the precipitation, seemingly outrunning the colder
air. However, model soundings do still hint at some "freezing" rain
potential on the backside. I say "freezing", due to the fact that
the ground will be rather wet and warm still, so although surface
temperatures will slide below freezing, no ice accumulation is
expected beside maybe a real light glaze on elevated surfaces.
Otherwise, the system slides to the far southeastern CWA on Sunday
night, ending all precipitation. With many surfaces still remaining
wet, there is a chance of some isolated black ice as temperatures
quickly fall Sunday night into Monday morning. Will have to monitor
this potential closely in the coming 24 hours.
Temperatures will continue to remain very mild this morning ahead of
the cold front, before crashing later in the day as the front sweeps
through. Lows will drop into the low 20s in southern Indiana and
the low 30s across southern KY. Highs on Monday will only climb
into the 30s and lower 40s.
.Long Term (Monday Night - Saturday)...
Issued at 320 AM EST Sun Jan 13 2013
Did not spend time diagnosing the models this forecast cycle because
of returns on 88D. Have blended with the previous forecast with the
new set of model consensus. The product is a forecast that has lows
near normal each day and highs not straying too far from normal
either. Rain chances are limited to the south and east forecast area
Monday night through Tuesday night. Model soundings indicate
temperatures close to freezing for most of the lower levels of the
atmosphere, so cannot rule out either rain or snow, should model
surface and low-level temperatures be off, so will continue to
advertise generally a rain/snow mix. Otherwise, from Wednesday on,
this forecast package will be dry.
&&
.Aviation (18Z TAF Issuance)...
Issued at 1205 PM EST Sun Jan 13 2013
The cold front that will be moving through the area has stalled out
for a bit this morning just to the northwest of SDF. This has
delayed the wind shift and the lower cigs from moving into the
region. Ceilings are still expected to drop to 1 kft or just below
over the next couple of hours at SDF and BWG. In addition, at BWG
some thunderstorms have developed in the area so will carry VCTS
there for a couple of hours.
The main challenge will be the wind shift and ceilings through this
TAF period. The lower ceilings will move out late this evening or
overnight as the cold front moves off to the southeast. Mid and high
clouds will likely hang around overnight and into tomorrow morning.
As the front passes through winds will shift to the northwest and
then to northerly through tomorrow morning.
&&
.Hydrology...
Unseasonably warm, moist air continues to be pooled into the Ohio
Valley. Decent amounts of rain continue to fall ahead of and along
an approaching cold front as the atmosphere is laden with moisture.
Precipitable water values are unseasonably high for this time of
year. Numerous rain showers are expected to continue throughout the
day. Additional rain amounts today look to be in the 1 to 2 inch
range. QPF totals are anticipated to be from about 1.5 to 4 inches
with locally higher amounts will be possible.
What this all translates to is the possibility for some minor areal
(see the issued Flood Watch for more details) and river flooding to
occur along prone banks. The location to watch initially looks to be
Dundee on the Rough River in the Green River basin which may reach
flood stage tonight. Additional spots to watch over the next 24 to
36 hours include locations along the Green and Salt River basins as
well as small creeks and streams. This includes Rochester, Alvaton
(Drakes Creek), Woodbury, and Boston (Rolling Fork River). As the
precipitation moves off toward the north and east, additional basins
will be under close observation as the rain flows downstream.
&&
.LMK WATCHES/WARNINGS/ADVISORIES...
IN...FLOOD WATCH UNTIL 7 PM EST /6 PM CST/ THIS EVENING FOR
INZ076>079-083-084-089>092.
KY...FLOOD WATCH UNTIL 7 PM EST /6 PM CST/ THIS EVENING FOR
KYZ023>042-045>048-053>055-061>065-070>077-081.
$$
Update...........EER
Short Term.......KD
Long Term........RJS
Aviation.........EER
Hydrology........LG/AMS
AREA FORECAST DISCUSSION
NWS LOUISVILLE KY
1206 PM EST SUN JAN 13 2013
...Updated Aviation Discussion...
.Forecast Update...
Issued at 940 AM EST Sun Jan 13 2013
The first heavier wave of precipitation has pushed to the east this
morning with mostly light rain across much of the forecast area.
Southwest portions of central Kentucky are most likely seeing some
moderate rain at this time. The highest rainfall report we have
received for the last 24 hours is a bit over 2 inches, though
portions of Dubois county have likely seen higher amounts.
Though the rain has begun to move out of southern Indiana, it looks
to increase again this afternoon. Another wave of rain is moving
across Arkansas. The latest runs of the rapid refresh and HRRR show
this area moving across the northwestern portions of the forecast
area. Additionally, some heavier rain showers look to continue to
move out of central TN into could central Kentucky. All told, much
of the region may see an additional one to possibly two inches of
rain today. Though not much areal flooding has been reported yet, it
will still be possible this afternoon as rains move once again
across saturated grounds.
Have adjusted the forecast based on current trends. In addition,
temperatures behind the front are falling faster than the previous
forecast, so did some adjustments to the hourly temps as well.
Updates are already out.
&&
.Short Term (Today through Monday)...
Issued at 330 AM EST Sun Jan 13 2013
...Flood Watch in Effect through Sunday Evening for areas along and
west of I-65...
Several disturbances ejecting out of strong southwest flow along a
slow-moving baroclinic zone will be the main story this short term
period. Heavy rain, strong winds, and even some wintry
precipitation on the backside all look in play over the next 36
hours.
The synoptic boundary is currently draped from western Ohio
southwest through southern Indiana and western Kentucky. As waves
ride along this boundary, convergence is enhanced and there have
been several rounds of strong, to occasionally severe thunderstorms
as storms accelerate along the mesoscale cold front. Radar has
shown a weakening trend over the last hour or so, and expect that to
be the general rule through early this morning. However, with 40-50
knots just off the surface, the stronger showers and isolated
thunderstorms will be able to pull down higher momentum air,
resulting in gusts up to 50 MPH.
The strong thunderstorm threat should continue to wane through the
morning hours as storms outrun the better instability. Then the
attention turns to the heavy rain potential. The 13/00Z NAM has a
pretty good handle on current trends, albeit a bit slow with the
precipitation. Thus, have leaned on it for the short term forecast,
but bringing things in a bit quicker. PWATs have risen to near 1.5
inches overnight (00Z OHX sounding came in with 1.29) and warm cloud
depths will remain at 10-12 thousand feet today. Copious moisture
transport on the nose of a low-level jet will feed into the
slow-moving boundary, producing moderate to locally heavy rainfall.
In addition, latest guidance continues to advertise another synoptic
shortwave lifting northeast along the boundary late this morning
into early this afternoon. This will help enhance precipitation
rates, especially across south central Kentucky generally west of
I-65. Think that 2 to 3 inches is possible there, with locally
higher amounts. Elsewhere, generally 1-2 inches is likely as the
front slowly progresses east.
In addition to the heavy rain potential, another added element to
this system is the chance for wintry precipitation as the front
exits. However, latest guidance continues to speed up the
progression of the precipitation, seemingly outrunning the colder
air. However, model soundings do still hint at some "freezing" rain
potential on the backside. I say "freezing", due to the fact that
the ground will be rather wet and warm still, so although surface
temperatures will slide below freezing, no ice accumulation is
expected beside maybe a real light glaze on elevated surfaces.
Otherwise, the system slides to the far southeastern CWA on Sunday
night, ending all precipitation. With many surfaces still remaining
wet, there is a chance of some isolated black ice as temperatures
quickly fall Sunday night into Monday morning. Will have to monitor
this potential closely in the coming 24 hours.
Temperatures will continue to remain very mild this morning ahead of
the cold front, before crashing later in the day as the front sweeps
through. Lows will drop into the low 20s in southern Indiana and
the low 30s across southern KY. Highs on Monday will only climb
into the 30s and lower 40s.
.Long Term (Monday Night - Saturday)...
Issued at 320 AM EST Sun Jan 13 2013
Did not spend time diagnosing the models this forecast cycle because
of returns on 88D. Have blended with the previous forecast with the
new set of model consensus. The product is a forecast that has lows
near normal each day and highs not straying too far from normal
either. Rain chances are limited to the south and east forecast area
Monday night through Tuesday night. Model soundings indicate
temperatures close to freezing for most of the lower levels of the
atmosphere, so cannot rule out either rain or snow, should model
surface and low-level temperatures be off, so will continue to
advertise generally a rain/snow mix. Otherwise, from Wednesday on,
this forecast package will be dry.
&&
.Aviation (18Z TAF Issuance)...
Issued at 1205 PM EST Sun Jan 13 2013
The cold front that will be moving through the area has stalled out
for a bit this morning just to the northwest of SDF. This has
delayed the wind shift and the lower cigs from moving into the
region. Ceilings are still expected to drop to 1 kft or just below
over the next couple of hours at SDF and BWG. In addition, at BWG
some thunderstorms have developed in the area so will carry VCTS
there for a couple of hours.
The main challenge will be the wind shift and ceilings through this
TAF period. The lower ceilings will move out late this evening or
overnight as the cold front moves off to the southeast. Mid and high
clouds will likely hang around overnight and into tomorrow morning.
As the front passes through winds will shift to the northwest and
then to northerly through tomorrow morning.
&&
.Hydrology...
Unseasonably warm, moist air continues to be pooled into the Ohio
Valley. Decent amounts of rain continue to fall ahead of and along
an approaching cold front as the atmosphere is laden with moisture.
Precipitable water values are unseasonably high for this time of
year. Numerous rain showers are expected to continue throughout the
day. Additional rain amounts today look to be in the 1 to 2 inch
range. QPF totals are anticipated to be from about 1.5 to 4 inches
with locally higher amounts will be possible.
What this all translates to is the possibility for some minor areal
(see the issued Flood Watch for more details) and river flooding to
occur along prone banks. The location to watch initially looks to be
Dundee on the Rough River in the Green River basin which may reach
flood stage tonight. Additional spots to watch over the next 24 to
36 hours include locations along the Green and Salt River basins as
well as small creeks and streams. This includes Rochester, Alvaton
(Drakes Creek), Woodbury, and Boston (Rolling Fork River). As the
precipitation moves off toward the north and east, additional basins
will be under close observation as the rain flows downstream.
&&
.LMK WATCHES/WARNINGS/ADVISORIES...
IN...FLOOD WATCH UNTIL 7 PM EST /6 PM CST/ THIS EVENING FOR
INZ076>079-083-084-089>092.
KY...FLOOD WATCH UNTIL 7 PM EST /6 PM CST/ THIS EVENING FOR
KYZ023>030-053-061>063-070>075.
$$
Update...........EER
Short Term.......KD
Long Term........RJS
Aviation.........EER
Hydrology........LG/AMS
AREA FORECAST DISCUSSION
NWS LOUISVILLE KY
942 AM EST SUN JAN 13 2013
.Forecast Update...
Issued at 940 AM EST Sun Jan 13 2013
The first heavier wave of precipitation has pushed to the east this
morning with mostly light rain across much of the forecast area.
Southwest portions of central Kentucky are most likely seeing some
moderate rain at this time. The highest rainfall report we have
received for the last 24 hours is a bit over 2 inches, though
portions of Dubois county have likely seen higher amounts.
Though the rain has begun to move out of southern Indiana, it looks
to increase again this afternoon. Another wave of rain is moving
across Arkansas. The latest runs of the rapid refresh and HRRR show
this area moving across the northwestern portions of the forecast
area. Additionally, some heavier rain showers look to continue to
move out of central TN into could central Kentucky. All told, much
of the region may see an additional one to possibly two inches of
rain today. Though not much areal flooding has been reported yet, it
will still be possible this afternoon as rains move once again
across saturated grounds.
Have adjusted the forecast based on current trends. In addition,
temperatures behind the front are falling faster than the previous
forecast, so did some adjustments to the hourly temps as well.
Updates are already out.
&&
.Short Term (Today through Monday)...
Issued at 330 AM EST Sun Jan 13 2013
...Flood Watch in Effect through Sunday Evening for areas along and
west of I-65...
Several disturbances ejecting out of strong southwest flow along a
slow-moving baroclinic zone will be the main story this short term
period. Heavy rain, strong winds, and even some wintry
precipitation on the backside all look in play over the next 36
hours.
The synoptic boundary is currently draped from western Ohio
southwest through southern Indiana and western Kentucky. As waves
ride along this boundary, convergence is enhanced and there have
been several rounds of strong, to occasionally severe thunderstorms
as storms accelerate along the mesoscale cold front. Radar has
shown a weakening trend over the last hour or so, and expect that to
be the general rule through early this morning. However, with 40-50
knots just off the surface, the stronger showers and isolated
thunderstorms will be able to pull down higher momentum air,
resulting in gusts up to 50 MPH.
The strong thunderstorm threat should continue to wane through the
morning hours as storms outrun the better instability. Then the
attention turns to the heavy rain potential. The 13/00Z NAM has a
pretty good handle on current trends, albeit a bit slow with the
precipitation. Thus, have leaned on it for the short term forecast,
but bringing things in a bit quicker. PWATs have risen to near 1.5
inches overnight (00Z OHX sounding came in with 1.29) and warm cloud
depths will remain at 10-12 thousand feet today. Copious moisture
transport on the nose of a low-level jet will feed into the
slow-moving boundary, producing moderate to locally heavy rainfall.
In addition, latest guidance continues to advertise another synoptic
shortwave lifting northeast along the boundary late this morning
into early this afternoon. This will help enhance precipitation
rates, especially across south central Kentucky generally west of
I-65. Think that 2 to 3 inches is possible there, with locally
higher amounts. Elsewhere, generally 1-2 inches is likely as the
front slowly progresses east.
In addition to the heavy rain potential, another added element to
this system is the chance for wintry precipitation as the front
exits. However, latest guidance continues to speed up the
progression of the precipitation, seemingly outrunning the colder
air. However, model soundings do still hint at some "freezing" rain
potential on the backside. I say "freezing", due to the fact that
the ground will be rather wet and warm still, so although surface
temperatures will slide below freezing, no ice accumulation is
expected beside maybe a real light glaze on elevated surfaces.
Otherwise, the system slides to the far southeastern CWA on Sunday
night, ending all precipitation. With many surfaces still remaining
wet, there is a chance of some isolated black ice as temperatures
quickly fall Sunday night into Monday morning. Will have to monitor
this potential closely in the coming 24 hours.
Temperatures will continue to remain very mild this morning ahead of
the cold front, before crashing later in the day as the front sweeps
through. Lows will drop into the low 20s in southern Indiana and
the low 30s across southern KY. Highs on Monday will only climb
into the 30s and lower 40s.
.Long Term (Monday Night - Saturday)...
Issued at 320 AM EST Sun Jan 13 2013
Did not spend time diagnosing the models this forecast cycle because
of returns on 88D. Have blended with the previous forecast with the
new set of model consensus. The product is a forecast that has lows
near normal each day and highs not straying too far from normal
either. Rain chances are limited to the south and east forecast area
Monday night through Tuesday night. Model soundings indicate
temperatures close to freezing for most of the lower levels of the
atmosphere, so cannot rule out either rain or snow, should model
surface and low-level temperatures be off, so will continue to
advertise generally a rain/snow mix. Otherwise, from Wednesday on,
this forecast package will be dry.
&&
.Aviation (12Z TAF Issuance)...
Issued at 634 AM EST Sun Jan 13 2013
Moderate to heavy rainfall continues to push east across all sites
this morning as a slow-moving cold front pushes across the region.
This will bring a prolonged period of MVFR to IFR conditions to all
sites through much of the TAF cycle.
Ceilings have been slow to lower this morning despite the rather
intense rainfall. However, upstream observations show that MVFR, or
even isolated IFR ceilings are on the doorstep of all sites.
Expect sites to bounce around both in visibilities and ceilings
throughout the day in the precipitation, from MVFR to high end IFR.
An extended area of IFR is apparent along the trailing edge of the
precipitation. Have used the latest guidance and observational
trends to time this area of prevailing IFR through KSDF and KBWG.
Thunderstorms will remain isolated as this system shifts east, so
have only put thunder in the KBWG TAF, where thunder is OCCURING now
and will continue for the next hour. However, an isolated rumble is
possible across all sites through the next several hours.
Winds have been rather random this morning as well, as individual
showers and waves along the boundary have shifted them in all
directions. Tried to time the synoptic boundary through the TAF
sites as best as possible, but winds will undoubtedly shift around
as outflow from showers affect sites.
Conditions should generally improve toward the end of the TAF
period, going back to VFR by early Monday morning as this system
pushes east.
&&
.Hydrology...
Unseasonably warm, moist air continues to be pooled into the Ohio
Valley. Decent amounts of rain continue to fall ahead of and along
an approaching cold front as the atmosphere is laden with moisture.
Precipitable water values are unseasonably high for this time of
year. Numerous rain showers are expected to continue throughout the
day. Additional rain amounts today look to be in the 1 to 2 inch
range. QPF totals are anticipated to be from about 1.5 to 4 inches
with locally higher amounts will be possible.
What this all translates to is the possibility for some minor areal
(see the issued Flood Watch for more details) and river flooding to
occur along prone banks. The location to watch initially looks to be
Dundee on the Rough River in the Green River basin which may reach
flood stage tonight. Additional spots to watch over the next 24 to
36 hours include locations along the Green and Salt River basins as
well as small creeks and streams. This includes Rochester, Alvaton
(Drakes Creek), Woodbury, and Boston (Rolling Fork River). As the
precipitation moves off toward the north and east, additional basins
will be under close observation as the rain flows downstream.
&&
.LMK WATCHES/WARNINGS/ADVISORIES...
IN...FLOOD WATCH UNTIL 7 PM EST /6 PM CST/ THIS EVENING FOR
INZ076>079-083-084-089>092.
KY...FLOOD WATCH UNTIL 7 PM EST /6 PM CST/ THIS EVENING FOR
KYZ023>030-053-061>063-070>075.
$$
Update...........EER
Short Term.......KD
Long Term........RJS
Aviation.........KD
Hydrology........LG/AMS
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
101 PM EST SUN JAN 13 2013
.UPDATE...
ISSUED AT 1128 AM EST SUN JAN 13 2013
CONTINUE TO FINE TUNE THE FORECAST FOR THE DOMINANT LES BAND THAT IS
PARALLELING THE W UPPER MI SHORELINE. VIS IN THIS BAND HAS BEEN ABLE
TO FALL TO 3/4SM AT CMX AS IT GLANCED THE AIRPORT. OUR ABILITY TO
LOCATE THIS BAND MAY BE DIMINISHING OVER THE NEXT FEW HOURS IF THE
MID CLOUDS OVER N WI CONTINUE TO SLOWLY FILTER N ACROSS LAKE
SUPERIOR. WILL CONTINUE TO KEEP MUCH OF THE MORE SIGNIFICANT SNOW
OUT OF IWD UNTIL MID TO LATE AFTERNOON...AS DEPICTED BY SOME OF THE
MORE SMALL SCALE MODEL TRENDS...GIVEN THE SLIGHT W TICK OF THE WINDS
AT THE LOWEST LEVELS.
&&
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 533 AM EST SUN JAN 13 2013
WV IMAGERY AND RUC ANALYSIS INDICATED A MID/UPPER LEVEL TROUGH FROM
CENTRAL CANADA THROUGH THE WRN PLAINS AND A RIDGE OFF THE EAST COAST
RESULTING IN SW FLOW FROM THE SRN PLAINS INTO THE GREAT LAKES. AN
UPSTREAM SHORTWAVE TROUGH WAS LOCATED OVER NEBRASKA. AT THE
SFC...THE MAIN TROUGH/FRONT AND FOCUS FOR HEAVIER PCPN WAS LOCATED WELL
TO THE SOUTH...FROM NW OH THROUGH WRN KY INTO NRN MS. TO THE
WEST...AN ARCTIC HIGH PRES RIDGE EXTENDED FROM ALBERTA/SASK INTO THE
WRN PLAINS. WITH MAINLY NW LOW LEVEL FLOW ACROSS THE NRN LAKES...LAKE
INDUCED TROUGHING HAS KEPT LOW LEVEL CONV FOCUSED NEAR THE LAKE FROM
IWD-P59. EVEN THOUGH 850 MB TEMPS TO AROUND -20C OVER WRN LAKE
SUPERIOR PROVIDED PLENTY OF INSTABILITY(LAKE INDUCED CAPE VALUES TO
AROUND 400 J/KG) LOW INVERSION HEIGHTS AROUND 4K FT WITH PROMINENT
MID LEVEL DRYING HAS LIMITED LES RATES WITH ONLY LIGHT ACCUMULATIONS
OF A FEW INCHES OVERNIGHT. THE DRY AIR...SLIGHTLY LOWER INVERSION
HEIGHTS AND 850 MB TEMPS ONLY NEAR -12C...HAS INHIBITED LES OVER THE
ERN LAKE.
MAIN FCST CONCERNS ARE LES TRENDS.
MODELS WERE CONSISTENT IN BRINGING THE NEBRASKA SHRTWV NORTHEAST
THROUGH THE WRN GREAT LAKES. EVEN WITH MODERATE TO STRONG 700-300 MB
QVECTOR CONV AHEAD OF THE SHRTWV...LITTLE SYNOPTIC PCPN IS EXPECTED
IN THE DRY AIRMASS TO THE NORTH OF THE MAIN FRONTAL BOUNDARY. SOME
LIGHT SNOW WILL BE POSSIBLE WITH THIS FEATURE WITH ANY ACCUMULATIONS
AMOUNTING TO TO A HALF INCH OR LESS.
THE MAIN IMPACT WILL BE TO INVIGORATE THE LES...ESPECIALLY LATE THIS
AFTERNOON AND EVENING...AS DEEPER MOISTURE MOVES IN AND INVERSION
HEIGHTS CLIMB AOA 7K FT WITH 850 MB TEMPS AROUND -19C. WITH THE DGZ IN
THE CONVECTIVE LAYER...SNOW/WATER RATIO VALUES SHOULD ALSO REMAIN
HIGH(FROM 25/1 TO 30/1). VEERING WINDS WILL SHIFT THE FOCUS OF THE
HEAVIER LES TO AREAS BTWN HOUGHTON AND THE PORCUPIN MOUNTAINS AND
ALSO WILL ALLOW THE LES TO PUSH INTO THE EAST (LOCATIONS FROM AU
TRAIN EASTWARD).
ONGOING ADVISORIES AND SNOWFALL AMOUNTS LOOK ON TRACK WITH 12 HOUR
AMOUNTS OF 1 TO 4 INCHES WEST TODAY AND 2 TO 5 INCHES TONIGHT. OVER
THE EAST...1 TO 3 INCHES ARE EXPECTED THIS AFTERNOON WITH AMOUNTS OF
3 TO 6 INCHES POSSIBLE...GREATEST NEAR THE LAKE EAST OF MUNISING.
SOME HIGHER AMOUNTS MAY BE POSSIBLE EAST IF A MORE DOMINANT BAND
DEVELOPS BUT CONFIDENCE IN THE LOCATION IS LIMITED GIVEN SIGNFICNAT
DIFFERENCES BETWEEN THE HIGHER RES MODELS.
.LONG TERM...(MONDAY THROUGH SATURDAY)
ISSUED AT 426 AM EST SUN JAN 13 2013
WEST TO NORTHWEST FLOW LAKE EFFECT WILL BE ONGOING AT THE START OF
THE LONG TERM PERIOD. BUT WITH THE SURFACE TROUGH OVER EASTERN LAKE
SUPERIOR DIMINISHING DURING THE MORNING DUE TO A HIGH PRESSURE
RIDGE MOVING THROUGH MN...EXPECT THE WINDS TO BACK THROUGH THE DAY
AND BE OUT OF THE WEST-SOUTHWEST BY 00Z TUESDAY. THIS WILL PUSH THE
LAKE EFFECT OFFSHORE OVER THE EAST BY EARLY AFTERNOON AND FOCUS THE
LAKE EFFECT OVER THE KEWEENAW PENINSULA OVER THE WEST. SINCE
INVERSION HEIGHTS ARE STILL IN THE 7-8KFT RANGE AND DELTA-T VALUES
ARE AROUND 22...CONDITIONS ARE FAVORABLE FOR MODERATE SNOW TO
CONTINUE ON MONDAY. WITH THE SOUTHERN EDGE OF THE LAKE EFFECT BAND
BEING AIDED BY ENHANCED CONVERGENCE FROM THE BACKING WINDS...THINK
THERE SHOULD BE AT LEAST ONE STRONGER BAND GRADUALLY DRIFTING NORTH
THROUGH NORTHERN HOUGHTON COUNTY DURING THE DAY. THE BIGGEST
CONCERN WILL BE THE NORTHWARD PUSH IN THE MORNING...WHICH THEN
STALLS IN THE AFTERNOON AS WHAT IS LEFT OF THE SURFACE TROUGH
STALLS OVER THE KEWEENAW. WHERE THIS BAND STALLS OR DOESN/T
STALL WILL DETERMINE SNOWFALL AMOUNTS. BUFKIT SOUNDINGS SHOWING
FAVORABLE CONDITIONS FOR VERY FLUFFY 30-1 SNOW RATIOS...AS THE BEST
OMEGA IS CENTERED RIGHT IN THE DGZ...MUCH OF THE CLOUD IS IN THE
DGZ...AND WIND SPEEDS ARE NOT OVERLY STRONG. WILL FOLLOW THAT IDEA
FOR THE FORECAST AND BUMP RATIOS TOWARDS THAT. WITH THE WAY MODELS
ARE LOOKING...COULD BE A PERIOD OF EVEN HEAVY SNOW DURING THE LATE
MORNING AND AFTERNOON HOURS...SINCE POCKET OF DEEPER H850-700
MOISTURE HELPS PUSH LAKE EFFECT SNOW PARAMETER VALUES WELL OVER 2.
HAVE FINE TUNED THE POPS DURING THIS PERIOD AND BUMPED SNOWFALL
AMOUNTS UP A FEW INCHES. 00Z RUNS OF BOTH THE NESTED 4KM NAM AND OUR
LOCAL WRF-ARW COBB SNOWFALL OUTPUT ARE INDICATING 10IN OF SNOW FOR
KCMX FROM 12Z MONDAY THROUGH 06Z TUESDAY. HAD SOME CONCERN EXTENDING
THE ADVISORY FOR ANOTHER 12HRS SINCE IT WAS A SIGNIFICANT JUMP FROM
PREVIOUS RUNS...BUT WITH GOING FORECAST VALUES OF 3-5 INCHES ON
MONDAY COULDN/T HOLD OFF ON IT.
WITH THE HIGH PRESSURE RIDGE SLIDING EAST ACROSS WISCONSIN ON
MONDAY NIGHT...INDICATIONS ARE THE WINDS BACKING MORE TO THE
SOUTHWEST. THIS WILL PUSH THE STRONGER SNOW TO THE NORTH THROUGH
KEWEENAW COUNTY AND BRING AN END TO THE LES FOR THE CWA FOR
A DAY OR TWO DUE TO H850 TEMPS WARMING TO -10C UNDER THE STRONG
SOUTHWESTERLY FLOW ON TUESDAY.
THIS INCREASING SOUTHWESTERLY FLOW IS IN RESPONSE TO AN APPROACHING
SHORTWAVE AND CLIPPER SYSTEM DROPPING THROUGH THE NORTHWEST FLOW
ALOFT. THIS COULD PRODUCE SOME BREEZY CONDITIONS ON TUESDAY
INTO TUESDAY NIGHT. BOTH NAM/GFS SHOWING H925 WINDS OF
40-50KTS...BUT A WEAK INVERSION MAY BE ENOUGH TO KEEP THAT
FROM REACHING THE SURFACE OVER LAND. OVER LAKE SUPERIOR...BUFKIT
SOUNDINGS SHOWING MUCH OF THAT REACHING THE SURFACE DUE TO STRONG
PRESSURE FALL /14MB IN 12HR/ MOVING ACROSS THE LAKE. THUS...HAVE
BUMPED WINDS UP A SOLID 10KTS TO GALES AND IF LATEST TRENDS ARE
CORRECT THEY WILL NEED TO GO ANOTHER 5-10KTS HIGHER. DEFINITELY
SEEING BETTER AGREEMENT IN THE MODELS WITH THE TIMING/TRACK OF THE
SYSTEM...ALTHOUGH THE ECMWF/GEM ARE A LITTLE FARTHER SOUTH AND
SLOWER WITH AN ELONGATED SURFACE TROUGH AS IT MOVES THROUGH LATE
TUESDAY NIGHT INTO WEDNESDAY. EITHER SOLUTION SHOULD LEAD TO AT
LEAST A DUSTING TO AN INCH OF SNOW CWA WIDE...BUT ECMWF/GEM COULD
PRODUCE SOME AREAS WITH A COUPLE INCHES OF SNOW.
COLD AIR WILL SURGE IN BEHIND THIS CLIPPER...AS THE POLAR VORTEX
DIVES SOUTHEAST TOWARDS JAMES BAY. AT THIS POINT IT LOOKS TO STAY
THERE...BUT IT WILL STILL LEAD TO H850 TEMPS IN THE LOW TO MID -20S.
WITH HIGH PRESSURE CENTERED IN THE CENTRAL PLAINS AND A LOW OVER
HUDSON BAY...EXPECT NORTHWESTERLY WINDS AT THE SURFACE AND THROUGH
H850. THIS WILL LEAD TO PERSISTENT LES IN THAT FAVORED WIND
DIRECTION WEDNESDAY NIGHT THROUGH THURSDAY NIGHT. WILL CONTINUE TO
HIGHLIGHT HIGH END LIKELY POPS IN THAT AREA. INTENSITY WILL DEPEND
ON THE INVERSION HEIGHTS AND IF ANY DEEPER MOISTURE OR SHORTWAVES
SWEEP THROUGH. 00Z GFS SHOWING LAKE INDUCED EQL HEIGHTS OF
7-9KFT...BUT MOISTURE REMAINS BELOW 5KFT WITH FORCING ON HIGHER
EDGE OF DGZ. THUS...POTENTIAL IS THERE FOR MODERATE SNOW...BUT
MOISTURE WILL BE CONTROLLING FACTOR.
GFS/ECMWF CONTINUING TO SHOW THE POTENTIAL FOR A WEAK SHORTWAVE
SLIDING THROUGH THE NORTHWEST FLOW ON FRIDAY AND AGAIN ON SATURDAY.
THIS LEADS TO SOME UNCERTAINTY IN THE LAKE EFFECT LOCATIONS AND
JUST LOW END CHANCE OR SLIGHT POPS ACROSS THE REST OF THE CWA.
AFTER A BELOW NORMAL START TO THE WORK WEEK...TEMPERATURES LOOK TO
RETURN TO NORMAL FOR TUESDAY/WEDNESDAY BEFORE FALLING 5-10 DEGREES
BELOW NORMAL FOR THE END OF THE WORK WEEK. FINALLY...00Z GFS HAS
TRENDED TOWARDS WHAT THE ECMWF HAS BEEN SHOWING WITH THE POLAR
VORTEX DIVING SOUTH INTO THE GREAT LAKES ON SUNDAY/MONDAY.
SIGNIFICANT DIFFERENCES IN THE AMOUNT OF COLD AIR BETWEEN THE
MODELS...SO IT WILL BE INTERESTING TO SEE WHICH ONE PANS OUT. IF
ECMWF IS RIGHT...H850 TEMPS WILL BE AROUND -35C AND WOULD LEAD TO
INLAND AREAS ON SLIGHTLY ABOVE ZERO FOR HIGHS.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z MONDAY AFTERNOON)
ISSUED AT 100 PM EST SUN JAN 13 2013
THE DOMINANT LAKE EFFECT SNOW BAND OVER WESTERN LAKE SUPERIOR IS
SLOWLY PUSHING FARTHER ONSHORE. WHILE IT IS BRINGING VIS TEMP DOWN
TO 1SM AT CMX...THE MORE DOWNSLOPE SW WIND DIRECTION AT IWD IS
POSTPONING THE ONSHORE MOVEMENT OF THE S PORTION OF THE BAND. STILL
ANOTHER SWATH OF MVFR CEILINGS HAS BEEN STEADILY SHIFTING N FROM W
WI...WITH MORE ONSHORE FLOW AT IWD TOWARD SUNSET. GIVEN THE LESS
FAVORABLE WIND DIRECTION AT SAW THROUGH THE ENTIRE PERIOD...ONLY
MVFR TO VFR CEILINGS/VIS ARE EXPECTED THROUGH 18Z MONDAY. MORE W-SW
WINDS WILL BRING DRIER AIR TO BOTH IWD AND SAW DURING THE DAY
MONDAY...WHILE LAKE EFFECT SNOW SHOWERS CONTINUE OFF AND ON AT CMX
THROUGH AT LEAST EARLY AFTERNOON.
&&
.MARINE...(FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 533 AM EST SUN JAN 13 2013
NORTHWEST WINDS ARE EXPECTED TO REMAIN AT OR BELOW 25 KNOTS THROUGH
MONDAY AS HIGH PRESSURE GRADUALLY BUILDS FROM THE PLAINS TOWARD THE
GREAT LAKES. A CLIPPER LOW PRES SYSTEM MOVING INTO SRN MANITOBA
TUESDAY AND NORTHERN ONTARIO TUE NIGHT WILL LIKELY BRING SW GALES
ACROSS LAKE SUPERIOR. AS THE LOW DEEPENS AND MOVES TOWARD NRN QUEBEC
WED...SOME NW GALES MAY ALSO BE POSSIBLE.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
LAKE EFFECT SNOW ADVISORY UNTIL 7 AM EST MONDAY FOR MIZ006-007.
LAKE EFFECT SNOW ADVISORY UNTIL 7 AM EST MONDAY FOR MIZ002.
LAKE EFFECT SNOW ADVISORY UNTIL 7 PM EST MONDAY FOR MIZ001-003.
LAKE SUPERIOR...
NONE.
LAKE MICHIGAN...
NONE.
&&
$$
UPDATE...KF
SHORT TERM...JLB
LONG TERM...SRF
AVIATION...KF
MARINE...JLB
AREA FORECAST DISCUSSION
NWS GRAND RAPIDS MI
1243 PM EST SUN JAN 13 2013
.SYNOPSIS...
ISSUED AT 325 AM EST SUN JAN 13 2013
A MIX OF PRECIPITATION INCLUDING SOME FREEZING RAIN THIS MORNING
WILL TRANSITION TO LIGHT SNOW SHOWERS THIS AFTERNOON. LIGHT SNOW
SHOWERS WILL CONTINUE TONIGHT INTO MONDAY. FAIRLY CLOSE TO NORMAL
TEMPERATURES ARE EXPECTED MOST OF THE UPCOMING WEEK WITH OCCASIONAL
LIGHT SNOW SHOWERS AND FLURRIES FROM TIME TO TIME.
&&
.UPDATE...
ISSUED AT 915 AM EST SUN JAN 13 2013
I UPDATED SINCE THERE IS MORE DRIZZLE THEN WAS CURRENTLY IN THE
FORECAST AND ALSO SINCE ALL OF THE MODELS I JUST LOOKED AT
(HRRR...RAP...NAM12...GFS AND ECMWF) ALL SHOW THE NEXT WAVE BRINGING
MEASURABLE PRECIPITATION TO NEARLY ALL OF THE CWA LATE THIS
AFTERNOON INTO THIS EVENING. SATELLITE LOOPS SHOW THE WAVE IS REAL
AND RADAR LOOPS ALSO SHOW THE WAVE NEEDING NORTHEAST FORM AR AND
MO HEADING THIS WAY TOO.
CURRENTLY THERE IS A DRY LAYER BETWEEN 10000 FT AND 20000 FT AS
SEEN ON RAP MODEL SOUNDINGS THAT IS NOT ALLOWING THE DGZ TO BE
SATURATED SO DRIZZLE/LIGHT RAIN IS FALLING INSTEAD OF SNOW OVER
OUR WESTERN CWA. BY EARLY TO MID AFTERNOON THE DEEPER MOISTURE
FROM THE NEXT SHORTWAVE COMES BACK IN SO THEN THE PRECIPITATION
SHOULD LARGELY BE SNOW FROM GRR NORTH AND WEST AND TRANSITION FROM
MIXED PRECIPITATION TO SNOW SOUTH AND EAST OF GRR (BY EVENING). I
DO NOT EXPECT MUCH SNOW OUT OF THIS... MOSTLY AN INCH OR LESS.
THIS MAY NEED UPDATING THROUGH.
UPDATE ISSUED AT 702 AM EST SUN JAN 13 2013
WILL BE CAN CELLING THE WINTER WEATHER ADVISORY AS BOTH RADAR AND
HRRR MODEL GUIDANCE INDICATE WE SHOULD BE PRECIPITATION FREE FOR
THE NEXT SEVERAL HOURS. ROAD WEATHER SENSORS AT CADILLAC/REED
CITY/LUDINGTON SHOW SURFACE TEMPERATURES STILL AROUND 33-35F EVEN
THOUGH AIR TEMPERATURES HAVE GENERALLY FALLEN BELOW FREEZING. ALL
OF THIS SUGGESTS THAT THERE SHOULD BE LITTLE EFFECT ON TRAVEL
CONDITIONS THE REST OF THIS MORNING. UPDATED FORECASTS WILL BE
COMING OUT SHORTLY.
&&
.SHORT TERM...(TODAY THROUGH TUESDAY AFTERNOON)
ISSUED AT 325 AM EST SUN JAN 13 2013
OUR PRIMARY SHORT TERM FCST CHALLENGE IS TO EVALUATE POTENTIAL FOR
FZRA THIS MORNING.
KGRR/RGNL RADAR TRENDS SHOW A LARGE AREA OF LGT TO MDT PCPN OVER OUR
AREA WITH RAIN NEAR TO SOUTH OF I-96 AND SOME MIXED PCPN BEING
REPORTED OVER OUR NORTHERN COUNTIES. SFC OBS AND LOCAL STORM REPORTS
INDICATE FAIRLY EXTENSIVE LIGHT TO MODERATE FZRA UPSTREAM ACROSS
PORTIONS OF WI/IL. PCPN WILL TRANSITION TO A PERIOD OF FZRA THIS
MORNING AS SFC TEMPS CONTINUE TO FALL SLOWLY TO FREEZING.
OUR GOING WINTER WX ADVISORY HEADLINE WILL REMAIN UNCHANGED WITH
HAZARDOUS TRAVEL CONDITIONS LIKELY TO DEVELOP A LITTLE LATER THIS
MORNING (TOWARD DAYBREAK THROUGH LATE MORNING) GIVEN THE MIXED
PCPN/FZRA AND SLOWLY FALLING SFC TEMPS IN NORTHERLY FLOW CAA.
PCPN WILL TRANSITION TO LIGHT SNOW SHOWERS THIS AFTN. LIGHT SNOW
SHOWERS WILL CONTINUE TONIGHT AND MONDAY BUT WITH VERY LIGHT
ACCUMULATIONS OF GENERALLY ONLY AROUND AN INCH OR LESS. MOST OF THAT
WILL COME THIS AFTERNOON AND TONIGHT WITH ONLY VERY LIGHT SNOW
SHOWERS AND FLURRIES EXPECTED TO LINGER MONDAY.
A FEW FLURRIES MAY LINGER INTO MONDAY NIGHT BUT MAINLY DRY
CONDITIONS ARE EXPECTED FOR THIS TIME FRAME WITH A SFC RIDGE IN
PLACE OVER THE LOWER GREAT LAKES REGION.
.LONG TERM...(TUESDAY NIGHT THROUGH SATURDAY)
ISSUED AT 325 AM EST SUN JAN 13 2013
MAIN CHANGE WAS TO INCREASE CHANCES FOR SNOW WEDNESDAY NIGHT AND
THURSDAY. LAST COUPLE RUNS OF THE PREFERRED ECMWF MODEL ADVERTISE A
MODERATELY STRONG CLIPPER AND ASSOCIATED COLD FRONT PASSING THROUGH
WEDNESDAY NIGHT. LAKE ENHANCED SNOW BEHIND THE CLIPPER LOOKS A BIT
MORE FAVORABLE EARLY THURSDAY WITH BETTER SATURATION IN THE DGZ AND
A BRIEF PERIOD OF COLD ADVECTION /850 MB TEMPERATURES DROPPING TO
AROUND -20C/.
OTHERWISE...NO OTHER SIGNIFICANT CHANGES WERE MADE.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z MONDAY AFTERNOON)
ISSUED AT 1744 PM EST SUN JAN 13 2013
WIDESPREAD IFR CONDITONS WILL PERSIST THIS AFTERNOON AND TONIGHT.
ANOTHER WAVE OF LOW PRESSURE IS MOVING NEWD ALONG THE COLD FRONT
AND WILL PRODUCE A PERIOD OF LIGHT SNOW. THE ERN TAF SITES WILL
SEE THE LONGEST PERIOD OF LIGHT SNOW AND KMKG WILL NOT SEE MUCH AT
ALL UNTIL THE OVERNIGHT HOURS WHEN SOME LIGHT LAKE EFFECT SNOW
SHOWERS WILL DEVELOP. AFTER 06Z CONDITIONS WILL BEGIN TO IMPROVE
WITH HIGHER CIGS/VSBYS. HOWEVER CLOSER TO THE LAKE SHORE SHSN WILL
DEVELOP WITH MVFR VSBYS EXPECTED.
&&
.MARINE...
ISSUED AT 325 AM EST SUN JAN 13 2013
THE SMALL CRAFT ADVISORY REMAINS IN EFFECT THROUGH MONDAY AS WAVE
HEIGHTS STAY UP TODAY WITH NORTHWEST TO NORTH WINDS AND COLDER AIR
MOVING IN. BRISK WEST WINDS WILL KEEP WAVE HEIGHTS UP TONIGHT INTO
MONDAY.
&&
.HYDROLOGY...
ISSUED AT 325 AM EST SUN JAN 13 2013
MODEST RIVER LEVEL RISES ARE ANTICIPATED IN RESPONSE TO THE RAINFALL
OVERNIGHT BUT NO SIGNIFICANT HYDRO ISSUES ARE EXPECTED SINCE
SIGNIFICANT PRECIPITATION WILL MOVE OUT LATER TODAY AND WITH THE
SIGNIFICANT COOLING TREND OF TEMPS.
&&
.GRR WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
LM...SMALL CRAFT ADVISORY UNTIL 3 PM EST MONDAY FOR LMZ844>849.
&&
$$
UPDATE...WDM
SYNOPSIS...LAURENS
SHORT TERM...LAURENS
LONG TERM...93
AVIATION...93
HYDROLOGY...LAURENS
MARINE...LAURENS
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
1128 AM EST SUN JAN 13 2013
.UPDATE...
ISSUED AT 1128 AM EST SUN JAN 13 2013
CONTINUE TO FINE TUNE THE FORECAST FOR THE DOMINANT LES BAND THAT IS
PARALLELING THE W UPPER MI SHORELINE. VIS IN THIS BAND HAS BEEN ABLE
TO FALL TO 3/4SM AT CMX AS IT GLANCED THE AIRPORT. OUR ABILITY TO
LOCATE THIS BAND MAY BE DIMINISHING OVER THE NEXT FEW HOURS IF THE
MID CLOUDS OVER N WI CONTINUE TO SLOWLY FILTER N ACROSS LAKE
SUPERIOR. WILL CONTINUE TO KEEP MUCH OF THE MORE SIGNIFICANT SNOW
OUT OF IWD UNTIL MID TO LATE AFTERNOON...AS DEPICTED BY SOME OF THE
MORE SMALL SCALE MODEL TRENDS...GIVEN THE SLIGHT W TICK OF THE WINDS
AT THE LOWEST LEVELS.
&&
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 533 AM EST SUN JAN 13 2013
WV IMAGERY AND RUC ANALYSIS INDICATED A MID/UPPER LEVEL TROUGH FROM
CENTRAL CANADA THROUGH THE WRN PLAINS AND A RIDGE OFF THE EAST COAST
RESULTING IN SW FLOW FROM THE SRN PLAINS INTO THE GREAT LAKES. AN
UPSTREAM SHORTWAVE TROUGH WAS LOCATED OVER NEBRASKA. AT THE
SFC...THE MAIN TROUGH/FRONT AND FOCUS FOR HEAVIER PCPN WAS LOCATED WELL
TO THE SOUTH...FROM NW OH THROUGH WRN KY INTO NRN MS. TO THE
WEST...AN ARCTIC HIGH PRES RIDGE EXTENDED FROM ALBERTA/SASK INTO THE
WRN PLAINS. WITH MAINLY NW LOW LEVEL FLOW ACROSS THE NRN LAKES...LAKE
INDUCED TROUGHING HAS KEPT LOW LEVEL CONV FOCUSED NEAR THE LAKE FROM
IWD-P59. EVEN THOUGH 850 MB TEMPS TO AROUND -20C OVER WRN LAKE
SUPERIOR PROVIDED PLENTY OF INSTABILITY(LAKE INDUCED CAPE VALUES TO
AROUND 400 J/KG) LOW INVERSION HEIGHTS AROUND 4K FT WITH PROMINENT
MID LEVEL DRYING HAS LIMITED LES RATES WITH ONLY LIGHT ACCUMULATIONS
OF A FEW INCHES OVERNIGHT. THE DRY AIR...SLIGHTLY LOWER INVERSION
HEIGHTS AND 850 MB TEMPS ONLY NEAR -12C...HAS INHIBITED LES OVER THE
ERN LAKE.
MAIN FCST CONCERNS ARE LES TRENDS.
MODELS WERE CONSISTENT IN BRINGING THE NEBRASKA SHRTWV NORTHEAST
THROUGH THE WRN GREAT LAKES. EVEN WITH MODERATE TO STRONG 700-300 MB
QVECTOR CONV AHEAD OF THE SHRTWV...LITTLE SYNOPTIC PCPN IS EXPECTED
IN THE DRY AIRMASS TO THE NORTH OF THE MAIN FRONTAL BOUNDARY. SOME
LIGHT SNOW WILL BE POSSIBLE WITH THIS FEATURE WITH ANY ACCUMULATIONS
AMOUNTING TO TO A HALF INCH OR LESS.
THE MAIN IMPACT WILL BE TO INVIGORATE THE LES...ESPECIALLY LATE THIS
AFTERNOON AND EVENING...AS DEEPER MOISTURE MOVES IN AND INVERSION
HEIGHTS CLIMB AOA 7K FT WITH 850 MB TEMPS AROUND -19C. WITH THE DGZ IN
THE CONVECTIVE LAYER...SNOW/WATER RATIO VALUES SHOULD ALSO REMAIN
HIGH(FROM 25/1 TO 30/1). VEERING WINDS WILL SHIFT THE FOCUS OF THE
HEAVIER LES TO AREAS BTWN HOUGHTON AND THE PORCUPIN MOUNTAINS AND
ALSO WILL ALLOW THE LES TO PUSH INTO THE EAST (LOCATIONS FROM AU
TRAIN EASTWARD).
ONGOING ADVISORIES AND SNOWFALL AMOUNTS LOOK ON TRACK WITH 12 HOUR
AMOUNTS OF 1 TO 4 INCHES WEST TODAY AND 2 TO 5 INCHES TONIGHT. OVER
THE EAST...1 TO 3 INCHES ARE EXPECTED THIS AFTERNOON WITH AMOUNTS OF
3 TO 6 INCHES POSSIBLE...GREATEST NEAR THE LAKE EAST OF MUNISING.
SOME HIGHER AMOUNTS MAY BE POSSIBLE EAST IF A MORE DOMINANT BAND
DEVELOPS BUT CONFIDENCE IN THE LOCATION IS LIMITED GIVEN SIGNFICNAT
DIFFERENCES BETWEEN THE HIGHER RES MODELS.
.LONG TERM...(MONDAY THROUGH SATURDAY)
ISSUED AT 426 AM EST SUN JAN 13 2013
WEST TO NORTHWEST FLOW LAKE EFFECT WILL BE ONGOING AT THE START OF
THE LONG TERM PERIOD. BUT WITH THE SURFACE TROUGH OVER EASTERN LAKE
SUPERIOR DIMINISHING DURING THE MORNING DUE TO A HIGH PRESSURE
RIDGE MOVING THROUGH MN...EXPECT THE WINDS TO BACK THROUGH THE DAY
AND BE OUT OF THE WEST-SOUTHWEST BY 00Z TUESDAY. THIS WILL PUSH THE
LAKE EFFECT OFFSHORE OVER THE EAST BY EARLY AFTERNOON AND FOCUS THE
LAKE EFFECT OVER THE KEWEENAW PENINSULA OVER THE WEST. SINCE
INVERSION HEIGHTS ARE STILL IN THE 7-8KFT RANGE AND DELTA-T VALUES
ARE AROUND 22...CONDITIONS ARE FAVORABLE FOR MODERATE SNOW TO
CONTINUE ON MONDAY. WITH THE SOUTHERN EDGE OF THE LAKE EFFECT BAND
BEING AIDED BY ENHANCED CONVERGENCE FROM THE BACKING WINDS...THINK
THERE SHOULD BE AT LEAST ONE STRONGER BAND GRADUALLY DRIFTING NORTH
THROUGH NORTHERN HOUGHTON COUNTY DURING THE DAY. THE BIGGEST
CONCERN WILL BE THE NORTHWARD PUSH IN THE MORNING...WHICH THEN
STALLS IN THE AFTERNOON AS WHAT IS LEFT OF THE SURFACE TROUGH
STALLS OVER THE KEWEENAW. WHERE THIS BAND STALLS OR DOESN/T
STALL WILL DETERMINE SNOWFALL AMOUNTS. BUFKIT SOUNDINGS SHOWING
FAVORABLE CONDITIONS FOR VERY FLUFFY 30-1 SNOW RATIOS...AS THE BEST
OMEGA IS CENTERED RIGHT IN THE DGZ...MUCH OF THE CLOUD IS IN THE
DGZ...AND WIND SPEEDS ARE NOT OVERLY STRONG. WILL FOLLOW THAT IDEA
FOR THE FORECAST AND BUMP RATIOS TOWARDS THAT. WITH THE WAY MODELS
ARE LOOKING...COULD BE A PERIOD OF EVEN HEAVY SNOW DURING THE LATE
MORNING AND AFTERNOON HOURS...SINCE POCKET OF DEEPER H850-700
MOISTURE HELPS PUSH LAKE EFFECT SNOW PARAMETER VALUES WELL OVER 2.
HAVE FINE TUNED THE POPS DURING THIS PERIOD AND BUMPED SNOWFALL
AMOUNTS UP A FEW INCHES. 00Z RUNS OF BOTH THE NESTED 4KM NAM AND OUR
LOCAL WRF-ARW COBB SNOWFALL OUTPUT ARE INDICATING 10IN OF SNOW FOR
KCMX FROM 12Z MONDAY THROUGH 06Z TUESDAY. HAD SOME CONCERN EXTENDING
THE ADVISORY FOR ANOTHER 12HRS SINCE IT WAS A SIGNIFICANT JUMP FROM
PREVIOUS RUNS...BUT WITH GOING FORECAST VALUES OF 3-5 INCHES ON
MONDAY COULDN/T HOLD OFF ON IT.
WITH THE HIGH PRESSURE RIDGE SLIDING EAST ACROSS WISCONSIN ON
MONDAY NIGHT...INDICATIONS ARE THE WINDS BACKING MORE TO THE
SOUTHWEST. THIS WILL PUSH THE STRONGER SNOW TO THE NORTH THROUGH
KEWEENAW COUNTY AND BRING AN END TO THE LES FOR THE CWA FOR
A DAY OR TWO DUE TO H850 TEMPS WARMING TO -10C UNDER THE STRONG
SOUTHWESTERLY FLOW ON TUESDAY.
THIS INCREASING SOUTHWESTERLY FLOW IS IN RESPONSE TO AN APPROACHING
SHORTWAVE AND CLIPPER SYSTEM DROPPING THROUGH THE NORTHWEST FLOW
ALOFT. THIS COULD PRODUCE SOME BREEZY CONDITIONS ON TUESDAY
INTO TUESDAY NIGHT. BOTH NAM/GFS SHOWING H925 WINDS OF
40-50KTS...BUT A WEAK INVERSION MAY BE ENOUGH TO KEEP THAT
FROM REACHING THE SURFACE OVER LAND. OVER LAKE SUPERIOR...BUFKIT
SOUNDINGS SHOWING MUCH OF THAT REACHING THE SURFACE DUE TO STRONG
PRESSURE FALL /14MB IN 12HR/ MOVING ACROSS THE LAKE. THUS...HAVE
BUMPED WINDS UP A SOLID 10KTS TO GALES AND IF LATEST TRENDS ARE
CORRECT THEY WILL NEED TO GO ANOTHER 5-10KTS HIGHER. DEFINITELY
SEEING BETTER AGREEMENT IN THE MODELS WITH THE TIMING/TRACK OF THE
SYSTEM...ALTHOUGH THE ECMWF/GEM ARE A LITTLE FARTHER SOUTH AND
SLOWER WITH AN ELONGATED SURFACE TROUGH AS IT MOVES THROUGH LATE
TUESDAY NIGHT INTO WEDNESDAY. EITHER SOLUTION SHOULD LEAD TO AT
LEAST A DUSTING TO AN INCH OF SNOW CWA WIDE...BUT ECMWF/GEM COULD
PRODUCE SOME AREAS WITH A COUPLE INCHES OF SNOW.
COLD AIR WILL SURGE IN BEHIND THIS CLIPPER...AS THE POLAR VORTEX
DIVES SOUTHEAST TOWARDS JAMES BAY. AT THIS POINT IT LOOKS TO STAY
THERE...BUT IT WILL STILL LEAD TO H850 TEMPS IN THE LOW TO MID -20S.
WITH HIGH PRESSURE CENTERED IN THE CENTRAL PLAINS AND A LOW OVER
HUDSON BAY...EXPECT NORTHWESTERLY WINDS AT THE SURFACE AND THROUGH
H850. THIS WILL LEAD TO PERSISTENT LES IN THAT FAVORED WIND
DIRECTION WEDNESDAY NIGHT THROUGH THURSDAY NIGHT. WILL CONTINUE TO
HIGHLIGHT HIGH END LIKELY POPS IN THAT AREA. INTENSITY WILL DEPEND
ON THE INVERSION HEIGHTS AND IF ANY DEEPER MOISTURE OR SHORTWAVES
SWEEP THROUGH. 00Z GFS SHOWING LAKE INDUCED EQL HEIGHTS OF
7-9KFT...BUT MOISTURE REMAINS BELOW 5KFT WITH FORCING ON HIGHER
EDGE OF DGZ. THUS...POTENTIAL IS THERE FOR MODERATE SNOW...BUT
MOISTURE WILL BE CONTROLLING FACTOR.
GFS/ECMWF CONTINUING TO SHOW THE POTENTIAL FOR A WEAK SHORTWAVE
SLIDING THROUGH THE NORTHWEST FLOW ON FRIDAY AND AGAIN ON SATURDAY.
THIS LEADS TO SOME UNCERTAINTY IN THE LAKE EFFECT LOCATIONS AND
JUST LOW END CHANCE OR SLIGHT POPS ACROSS THE REST OF THE CWA.
AFTER A BELOW NORMAL START TO THE WORK WEEK...TEMPERATURES LOOK TO
RETURN TO NORMAL FOR TUESDAY/WEDNESDAY BEFORE FALLING 5-10 DEGREES
BELOW NORMAL FOR THE END OF THE WORK WEEK. FINALLY...00Z GFS HAS
TRENDED TOWARDS WHAT THE ECMWF HAS BEEN SHOWING WITH THE POLAR
VORTEX DIVING SOUTH INTO THE GREAT LAKES ON SUNDAY/MONDAY.
SIGNIFICANT DIFFERENCES IN THE AMOUNT OF COLD AIR BETWEEN THE
MODELS...SO IT WILL BE INTERESTING TO SEE WHICH ONE PANS OUT. IF
ECMWF IS RIGHT...H850 TEMPS WILL BE AROUND -35C AND WOULD LEAD TO
INLAND AREAS ON SLIGHTLY ABOVE ZERO FOR HIGHS.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z MONDAY MORNING)
ISSUED AT 704 AM EST SUN JAN 13 2013
EXPECT MVFR CONDITIONS TO PREVAIL AT CMX/IWD WITH SURGE OF COLD AIR
OVER THE RELATIVELY WARM WATERS OF LAKE SUPERIOR AND AN UPSLOPE W-NW
WIND. THERE COULD BE SOME HEAVIER SHSN/IFR CONDITIONS MAINLY AT CMX.
SINCE THE NW LOW LEVEL WILL DOWNSLOPE AT SAW...THE MVFR CONDITIONS
MAY GIVE WAY TO VFR AT TIMES. THE APPROACH OF ANOTHER SHORTWAVE
TROUGH THIS AFTERNOON WILL INCREASE CHANCE OF HEAVIER SHSN/IFR
VSBYS AT IWD/CMX IN THE PRESENCE OF AN UPSLOPE WIND. ALTHOUGH SOME
-SHSN MAY IMPACT SAW AS WELL...DOWNSLOPE WIND WILL LIMIT THE POTENTIAL
FOR ANY WORSE THAN MVFR CONDITIONS.
&&
.MARINE...(FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 533 AM EST SUN JAN 13 2013
NORTHWEST WINDS ARE EXPECTED TO REMAIN AT OR BELOW 25 KNOTS THROUGH
MONDAY AS HIGH PRESSURE GRADUALLY BUILDS FROM THE PLAINS TOWARD THE
GREAT LAKES. A CLIPPER LOW PRES SYSTEM MOVING INTO SRN MANITOBA
TUESDAY AND NORTHERN ONTARIO TUE NIGHT WILL LIKELY BRING SW GALES
ACROSS LAKE SUPERIOR. AS THE LOW DEEPENS AND MOVES TOWARD NRN QUEBEC
WED...SOME NW GALES MAY ALSO BE POSSIBLE.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
LAKE EFFECT SNOW ADVISORY UNTIL 7 AM EST MONDAY FOR MIZ006-007.
LAKE EFFECT SNOW ADVISORY UNTIL 7 AM EST MONDAY FOR MIZ002.
LAKE EFFECT SNOW ADVISORY UNTIL 7 PM EST MONDAY FOR MIZ001-003.
LAKE SUPERIOR...
NONE.
LAKE MICHIGAN...
NONE.
&&
$$
UPDATE...KF
SHORT TERM...JLB
LONG TERM...SRF
AVIATION...JLB
MARINE...JLB
AREA FORECAST DISCUSSION
NWS GRAND RAPIDS MI
914 AM EST SUN JAN 13 2013
.SYNOPSIS...
ISSUED AT 325 AM EST SUN JAN 13 2013
A MIX OF PRECIPITATION INCLUDING SOME FREEZING RAIN THIS MORNING
WILL TRANSITION TO LIGHT SNOW SHOWERS THIS AFTERNOON. LIGHT SNOW
SHOWERS WILL CONTINUE TONIGHT INTO MONDAY. FAIRLY CLOSE TO NORMAL
TEMPERATURES ARE EXPECTED MOST OF THE UPCOMING WEEK WITH OCCASIONAL
LIGHT SNOW SHOWERS AND FLURRIES FROM TIME TO TIME.
&&
.UPDATE...
ISSUED AT 915 AM EST SUN JAN 13 2013
I UPDATED SINCE THERE IS MORE DRIZZLE THEN WAS CURRENTLY IN THE
FORECAST AND ALSO SINCE ALL OF THE MODELS I JUST LOOKED AT
(HRRR...RAP...NAM12...GFS AND ECMWF) ALL SHOW THE NEXT WAVE BRINGING
MEASURABLE PRECIPITATION TO NEARLY ALL OF THE CWA LATE THIS
AFTERNOON INTO THIS EVENING. SATELLITE LOOPS SHOW THE WAVE IS REAL
AND RADAR LOOPS ALSO SHOW THE WAVE NEEDING NORTHEAST FORM AR AND
MO HEADING THIS WAY TOO.
CURRENTLY THERE IS A DRY LAYER BETWEEN 10000 FT AND 20000 FT AS
SEEN ON RAP MODEL SOUNDINGS THAT IS NOT ALLOWING THE DGZ TO BE
SATURATED SO DRIZZLE/LIGHT RAIN IS FALLING INSTEAD OF SNOW OVER
OUR WESTERN CWA. BY EARLY TO MID AFTERNOON THE DEEPER MOISTURE
FROM THE NEXT SHORTWAVE COMES BACK IN SO THEN THE PRECIPITATION
SHOULD LARGELY BE SNOW FROM GRR NORTH AND WEST AND TRANSITION FROM
MIXED PRECIPITATION TO SNOW SOUTH AND EAST OF GRR (BY EVENING). I
DO NOT EXPECT MUCH SNOW OUT OF THIS... MOSTLY AN INCH OR LESS.
THIS MAY NEED UPDATING THROUGH.
UPDATE ISSUED AT 702 AM EST SUN JAN 13 2013
WILL BE CAN CELLING THE WINTER WEATHER ADVISORY AS BOTH RADAR AND
HRRR MODEL GUIDANCE INDICATE WE SHOULD BE PRECIPITATION FREE FOR
THE NEXT SEVERAL HOURS. ROAD WEATHER SENSORS AT CADILLAC/REED
CITY/LUDINGTON SHOW SURFACE TEMPERATURES STILL AROUND 33-35F EVEN
THOUGH AIR TEMPERATURES HAVE GENERALLY FALLEN BELOW FREEZING. ALL
OF THIS SUGGESTS THAT THERE SHOULD BE LITTLE EFFECT ON TRAVEL
CONDITIONS THE REST OF THIS MORNING. UPDATED FORECASTS WILL BE
COMING OUT SHORTLY.
&&
.SHORT TERM...(TODAY THROUGH TUESDAY AFTERNOON)
ISSUED AT 325 AM EST SUN JAN 13 2013
OUR PRIMARY SHORT TERM FCST CHALLENGE IS TO EVALUATE POTENTIAL FOR
FZRA THIS MORNING.
KGRR/RGNL RADAR TRENDS SHOW A LARGE AREA OF LGT TO MDT PCPN OVER OUR
AREA WITH RAIN NEAR TO SOUTH OF I-96 AND SOME MIXED PCPN BEING
REPORTED OVER OUR NORTHERN COUNTIES. SFC OBS AND LOCAL STORM REPORTS
INDICATE FAIRLY EXTENSIVE LIGHT TO MODERATE FZRA UPSTREAM ACROSS
PORTIONS OF WI/IL. PCPN WILL TRANSITION TO A PERIOD OF FZRA THIS
MORNING AS SFC TEMPS CONTINUE TO FALL SLOWLY TO FREEZING.
OUR GOING WINTER WX ADVISORY HEADLINE WILL REMAIN UNCHANGED WITH
HAZARDOUS TRAVEL CONDITIONS LIKELY TO DEVELOP A LITTLE LATER THIS
MORNING (TOWARD DAYBREAK THROUGH LATE MORNING) GIVEN THE MIXED
PCPN/FZRA AND SLOWLY FALLING SFC TEMPS IN NORTHERLY FLOW CAA.
PCPN WILL TRANSITION TO LIGHT SNOW SHOWERS THIS AFTN. LIGHT SNOW
SHOWERS WILL CONTINUE TONIGHT AND MONDAY BUT WITH VERY LIGHT
ACCUMULATIONS OF GENERALLY ONLY AROUND AN INCH OR LESS. MOST OF THAT
WILL COME THIS AFTERNOON AND TONIGHT WITH ONLY VERY LIGHT SNOW
SHOWERS AND FLURRIES EXPECTED TO LINGER MONDAY.
A FEW FLURRIES MAY LINGER INTO MONDAY NIGHT BUT MAINLY DRY
CONDITIONS ARE EXPECTED FOR THIS TIME FRAME WITH A SFC RIDGE IN
PLACE OVER THE LOWER GREAT LAKES REGION.
.LONG TERM...(TUESDAY NIGHT THROUGH SATURDAY)
ISSUED AT 325 AM EST SUN JAN 13 2013
MAIN CHANGE WAS TO INCREASE CHANCES FOR SNOW WEDNESDAY NIGHT AND
THURSDAY. LAST COUPLE RUNS OF THE PREFERRED ECMWF MODEL ADVERTISE A
MODERATELY STRONG CLIPPER AND ASSOCIATED COLD FRONT PASSING THROUGH
WEDNESDAY NIGHT. LAKE ENHANCED SNOW BEHIND THE CLIPPER LOOKS A BIT
MORE FAVORABLE EARLY THURSDAY WITH BETTER SATURATION IN THE DGZ AND
A BRIEF PERIOD OF COLD ADVECTION /850 MB TEMPERATURES DROPPING TO
AROUND -20C/.
OTHERWISE...NO OTHER SIGNIFICANT CHANGES WERE MADE.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z MONDAY MORNING)
ISSUED AT 634 AM EST SUN JAN 13 2013
MAIN CHANGES TO TAFS WERE TO DELAY THE TRANSITION FROM RAIN...TO FREEZING
RAIN/ICE PELLETS...TO SNOW ACROSS THE TERMINALS FROM NORTHWEST TO SOUTHEAST.
RADAR AND COMPUTER MODELS INDICATE A LULL IN PRECIPITATION THAT SHOULD
LAST MOST OF THE MORNING ACROSS SOUTHWEST LOWER MICHIGAN.
EXPECT IFR CIGS EARLY THIS MORNING AT MOST TERMINALS GRADUALLY LIFTING
BUT LIKELY STAYING BELOW FUEL ALTERNATE THRESHOLD OF 2000 FT AGL AREAWIDE.
CIGS ARE THE GREATEST CONCERN FOR FLIGHT RESTRICTIONS AND UNFORTUNATELY
A LOT OF UNCERTAINTY EXISTS IN THIS CRITICAL ASPECT OF THE FORECAST.
OTHERWISE...MODERATE INTENSITY PRECIPITATION MIGHT BRIEFLY DROP
VISIBILITIES BELOW FUEL ALTERNATE THRESHOLDS THIS AFTERNOON AT THE
KAZO/KBTL/KJXN TERMINALS.
&&
.MARINE...
ISSUED AT 325 AM EST SUN JAN 13 2013
THE SMALL CRAFT ADVISORY REMAINS IN EFFECT THROUGH MONDAY AS WAVE
HEIGHTS STAY UP TODAY WITH NORTHWEST TO NORTH WINDS AND COLDER AIR
MOVING IN. BRISK WEST WINDS WILL KEEP WAVE HEIGHTS UP TONIGHT INTO
MONDAY.
&&
.HYDROLOGY...
ISSUED AT 325 AM EST SUN JAN 13 2013
MODEST RIVER LEVEL RISES ARE ANTICIPATED IN RESPONSE TO THE RAINFALL
OVERNIGHT BUT NO SIGNIFICANT HYDRO ISSUES ARE EXPECTED SINCE
SIGNIFICANT PRECIPITATION WILL MOVE OUT LATER TODAY AND WITH THE
SIGNIFICANT COOLING TREND OF TEMPS.
&&
.GRR WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
LM...SMALL CRAFT ADVISORY UNTIL 3 PM EST MONDAY FOR LMZ844>849.
&&
$$
UPDATE...WDM
SYNOPSIS...LAURENS
SHORT TERM...LAURENS
LONG TERM...93
AVIATION...TJT
HYDROLOGY...LAURENS
MARINE...LAURENS
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
707 AM EST SUN JAN 13 2013
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 533 AM EST SUN JAN 13 2013
WV IMAGERY AND RUC ANALYSIS INDICATED A MID/UPPER LEVEL TROUGH FROM
CENTRAL CANADA THROUGH THE WRN PLAINS AND A RIDGE OFF THE EAST COAST
RESULTING IN SW FLOW FROM THE SRN PLAINS INTO THE GREAT LAKES. AN
UPSTREAM SHORTWAVE TROUGH WAS LOCATED OVER NEBRASKA. AT THE
SFC...THE MAIN TROUGH/FRONT AND FOCUS FOR HEAVIER PCPN WAS LOCATED WELL
TO THE SOUTH...FROM NW OH THROUGH WRN KY INTO NRN MS. TO THE
WEST...AN ARCTIC HIGH PRES RIDGE EXTENDED FROM ALBERTA/SASK INTO THE
WRN PLAINS. WITH MAINLY NW LOW LEVEL FLOW ACROSS THE NRN LAKES...LAKE
INDUCED TROUGHING HAS KEPT LOW LEVEL CONV FOCUSED NEAR THE LAKE FROM
IWD-P59. EVEN THOUGH 850 MB TEMPS TO AROUND -20C OVER WRN LAKE
SUPERIOR PROVIDED PLENTY OF INSTABILITY(LAKE INDUCED CAPE VALUES TO
AROUND 400 J/KG) LOW INVERSION HEIGHTS AROUND 4K FT WITH PROMINENT
MID LEVEL DRYING HAS LIMITED LES RATES WITH ONLY LIGHT ACCUMULATIONS
OF A FEW INCHES OVERNIGHT. THE DRY AIR...SLIGHTLY LOWER INVERSION
HEIGHTS AND 850 MB TEMPS ONLY NEAR -12C...HAS INHIBITED LES OVER THE
ERN LAKE.
MAIN FCST CONCERNS ARE LES TRENDS.
MODELS WERE CONSISTENT IN BRINGING THE NEBRASKA SHRTWV NORTHEAST
THROUGH THE WRN GREAT LAKES. EVEN WITH MODERATE TO STRONG 700-300 MB
QVECTOR CONV AHEAD OF THE SHRTWV...LITTLE SYNOPTIC PCPN IS EXPECTED
IN THE DRY AIRMASS TO THE NORTH OF THE MAIN FRONTAL BOUNDARY. SOME
LIGHT SNOW WILL BE POSSIBLE WITH THIS FEATURE WITH ANY ACCUMULATIONS
AMOUNTING TO TO A HALF INCH OR LESS.
THE MAIN IMPACT WILL BE TO INVIGORATE THE LES...ESPECIALLY LATE THIS
AFTERNOON AND EVENING...AS DEEPER MOISTURE MOVES IN AND INVERSION
HEIGHTS CLIMB AOA 7K FT WITH 850 MB TEMPS AROUND -19C. WITH THE DGZ IN
THE CONVECTIVE LAYER...SNOW/WATER RATIO VALUES SHOULD ALSO REMAIN
HIGH(FROM 25/1 TO 30/1). VEERING WINDS WILL SHIFT THE FOCUS OF THE
HEAVIER LES TO AREAS BTWN HOUGHTON AND THE PORCUPIN MOUNTAINS AND
ALSO WILL ALLOW THE LES TO PUSH INTO THE EAST (LOCATIONS FROM AU
TRAIN EASTWARD).
ONGOING ADVISORIES AND SNOWFALL AMOUNTS LOOK ON TRACK WITH 12 HOUR
AMOUNTS OF 1 TO 4 INCHES WEST TODAY AND 2 TO 5 INCHES TONIGHT. OVER
THE EAST...1 TO 3 INCHES ARE EXPECTED THIS AFTERNOON WITH AMOUNTS OF
3 TO 6 INCHES POSSIBLE...GREATEST NEAR THE LAKE EAST OF MUNISING.
SOME HIGHER AMOUNTS MAY BE POSSIBLE EAST IF A MORE DOMINANT BAND
DEVELOPS BUT CONFIDENCE IN THE LOCATION IS LIMITED GIVEN SIGNFICNAT
DIFFERENCES BETWEEN THE HIGHER RES MODELS.
.LONG TERM...(MONDAY THROUGH SATURDAY)
ISSUED AT 426 AM EST SUN JAN 13 2013
WEST TO NORTHWEST FLOW LAKE EFFECT WILL BE ONGOING AT THE START OF
THE LONG TERM PERIOD. BUT WITH THE SURFACE TROUGH OVER EASTERN LAKE
SUPERIOR DIMINISHING DURING THE MORNING DUE TO A HIGH PRESSURE
RIDGE MOVING THROUGH MN...EXPECT THE WINDS TO BACK THROUGH THE DAY
AND BE OUT OF THE WEST-SOUTHWEST BY 00Z TUESDAY. THIS WILL PUSH THE
LAKE EFFECT OFFSHORE OVER THE EAST BY EARLY AFTERNOON AND FOCUS THE
LAKE EFFECT OVER THE KEWEENAW PENINSULA OVER THE WEST. SINCE
INVERSION HEIGHTS ARE STILL IN THE 7-8KFT RANGE AND DELTA-T VALUES
ARE AROUND 22...CONDITIONS ARE FAVORABLE FOR MODERATE SNOW TO
CONTINUE ON MONDAY. WITH THE SOUTHERN EDGE OF THE LAKE EFFECT BAND
BEING AIDED BY ENHANCED CONVERGENCE FROM THE BACKING WINDS...THINK
THERE SHOULD BE AT LEAST ONE STRONGER BAND GRADUALLY DRIFTING NORTH
THROUGH NORTHERN HOUGHTON COUNTY DURING THE DAY. THE BIGGEST
CONCERN WILL BE THE NORTHWARD PUSH IN THE MORNING...WHICH THEN
STALLS IN THE AFTERNOON AS WHAT IS LEFT OF THE SURFACE TROUGH
STALLS OVER THE KEWEENAW. WHERE THIS BAND STALLS OR DOESN/T
STALL WILL DETERMINE SNOWFALL AMOUNTS. BUFKIT SOUNDINGS SHOWING
FAVORABLE CONDITIONS FOR VERY FLUFFY 30-1 SNOW RATIOS...AS THE BEST
OMEGA IS CENTERED RIGHT IN THE DGZ...MUCH OF THE CLOUD IS IN THE
DGZ...AND WIND SPEEDS ARE NOT OVERLY STRONG. WILL FOLLOW THAT IDEA
FOR THE FORECAST AND BUMP RATIOS TOWARDS THAT. WITH THE WAY MODELS
ARE LOOKING...COULD BE A PERIOD OF EVEN HEAVY SNOW DURING THE LATE
MORNING AND AFTERNOON HOURS...SINCE POCKET OF DEEPER H850-700
MOISTURE HELPS PUSH LAKE EFFECT SNOW PARAMETER VALUES WELL OVER 2.
HAVE FINE TUNED THE POPS DURING THIS PERIOD AND BUMPED SNOWFALL
AMOUNTS UP A FEW INCHES. 00Z RUNS OF BOTH THE NESTED 4KM NAM AND OUR
LOCAL WRF-ARW COBB SNOWFALL OUTPUT ARE INDICATING 10IN OF SNOW FOR
KCMX FROM 12Z MONDAY THROUGH 06Z TUESDAY. HAD SOME CONCERN EXTENDING
THE ADVISORY FOR ANOTHER 12HRS SINCE IT WAS A SIGNIFICANT JUMP FROM
PREVIOUS RUNS...BUT WITH GOING FORECAST VALUES OF 3-5 INCHES ON
MONDAY COULDN/T HOLD OFF ON IT.
WITH THE HIGH PRESSURE RIDGE SLIDING EAST ACROSS WISCONSIN ON
MONDAY NIGHT...INDICATIONS ARE THE WINDS BACKING MORE TO THE
SOUTHWEST. THIS WILL PUSH THE STRONGER SNOW TO THE NORTH THROUGH
KEWEENAW COUNTY AND BRING AN END TO THE LES FOR THE CWA FOR
A DAY OR TWO DUE TO H850 TEMPS WARMING TO -10C UNDER THE STRONG
SOUTHWESTERLY FLOW ON TUESDAY.
THIS INCREASING SOUTHWESTERLY FLOW IS IN RESPONSE TO AN APPROACHING
SHORTWAVE AND CLIPPER SYSTEM DROPPING THROUGH THE NORTHWEST FLOW
ALOFT. THIS COULD PRODUCE SOME BREEZY CONDITIONS ON TUESDAY
INTO TUESDAY NIGHT. BOTH NAM/GFS SHOWING H925 WINDS OF
40-50KTS...BUT A WEAK INVERSION MAY BE ENOUGH TO KEEP THAT
FROM REACHING THE SURFACE OVER LAND. OVER LAKE SUPERIOR...BUFKIT
SOUNDINGS SHOWING MUCH OF THAT REACHING THE SURFACE DUE TO STRONG
PRESSURE FALL /14MB IN 12HR/ MOVING ACROSS THE LAKE. THUS...HAVE
BUMPED WINDS UP A SOLID 10KTS TO GALES AND IF LATEST TRENDS ARE
CORRECT THEY WILL NEED TO GO ANOTHER 5-10KTS HIGHER. DEFINITELY
SEEING BETTER AGREEMENT IN THE MODELS WITH THE TIMING/TRACK OF THE
SYSTEM...ALTHOUGH THE ECMWF/GEM ARE A LITTLE FARTHER SOUTH AND
SLOWER WITH AN ELONGATED SURFACE TROUGH AS IT MOVES THROUGH LATE
TUESDAY NIGHT INTO WEDNESDAY. EITHER SOLUTION SHOULD LEAD TO AT
LEAST A DUSTING TO AN INCH OF SNOW CWA WIDE...BUT ECMWF/GEM COULD
PRODUCE SOME AREAS WITH A COUPLE INCHES OF SNOW.
COLD AIR WILL SURGE IN BEHIND THIS CLIPPER...AS THE POLAR VORTEX
DIVES SOUTHEAST TOWARDS JAMES BAY. AT THIS POINT IT LOOKS TO STAY
THERE...BUT IT WILL STILL LEAD TO H850 TEMPS IN THE LOW TO MID -20S.
WITH HIGH PRESSURE CENTERED IN THE CENTRAL PLAINS AND A LOW OVER
HUDSON BAY...EXPECT NORTHWESTERLY WINDS AT THE SURFACE AND THROUGH
H850. THIS WILL LEAD TO PERSISTENT LES IN THAT FAVORED WIND
DIRECTION WEDNESDAY NIGHT THROUGH THURSDAY NIGHT. WILL CONTINUE TO
HIGHLIGHT HIGH END LIKELY POPS IN THAT AREA. INTENSITY WILL DEPEND
ON THE INVERSION HEIGHTS AND IF ANY DEEPER MOISTURE OR SHORTWAVES
SWEEP THROUGH. 00Z GFS SHOWING LAKE INDUCED EQL HEIGHTS OF
7-9KFT...BUT MOISTURE REMAINS BELOW 5KFT WITH FORCING ON HIGHER
EDGE OF DGZ. THUS...POTENTIAL IS THERE FOR MODERATE SNOW...BUT
MOISTURE WILL BE CONTROLLING FACTOR.
GFS/ECMWF CONTINUING TO SHOW THE POTENTIAL FOR A WEAK SHORTWAVE
SLIDING THROUGH THE NORTHWEST FLOW ON FRIDAY AND AGAIN ON SATURDAY.
THIS LEADS TO SOME UNCERTAINTY IN THE LAKE EFFECT LOCATIONS AND
JUST LOW END CHANCE OR SLIGHT POPS ACROSS THE REST OF THE CWA.
AFTER A BELOW NORMAL START TO THE WORK WEEK...TEMPERATURES LOOK TO
RETURN TO NORMAL FOR TUESDAY/WEDNESDAY BEFORE FALLING 5-10 DEGREES
BELOW NORMAL FOR THE END OF THE WORK WEEK. FINALLY...00Z GFS HAS
TRENDED TOWARDS WHAT THE ECMWF HAS BEEN SHOWING WITH THE POLAR
VORTEX DIVING SOUTH INTO THE GREAT LAKES ON SUNDAY/MONDAY.
SIGNIFICANT DIFFERENCES IN THE AMOUNT OF COLD AIR BETWEEN THE
MODELS...SO IT WILL BE INTERESTING TO SEE WHICH ONE PANS OUT. IF
ECMWF IS RIGHT...H850 TEMPS WILL BE AROUND -35C AND WOULD LEAD TO
INLAND AREAS ON SLIGHTLY ABOVE ZERO FOR HIGHS.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z MONDAY MORNING)
ISSUED AT 704 AM EST SUN JAN 13 2013
EXPECT MVFR CONDITIONS TO PREVAIL AT CMX/IWD WITH SURGE OF COLD AIR
OVER THE RELATIVELY WARM WATERS OF LAKE SUPERIOR AND AN UPSLOPE W-NW
WIND. THERE COULD BE SOME HEAVIER SHSN/IFR CONDITIONS MAINLY AT CMX.
SINCE THE NW LOW LEVEL WILL DOWNSLOPE AT SAW...THE MVFR CONDITIONS
MAY GIVE WAY TO VFR AT TIMES. THE APPROACH OF ANOTHER SHORTWAVE
TROUGH THIS AFTERNOON WILL INCREASE CHANCE OF HEAVIER SHSN/IFR
VSBYS AT IWD/CMX IN THE PRESENCE OF AN UPSLOPE WIND. ALTHOUGH SOME
-SHSN MAY IMPACT SAW AS WELL...DOWNSLOPE WIND WILL LIMIT THE POTENTIAL
FOR ANY WORSE THAN MVFR CONDITIONS.
&&
.MARINE...(FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 533 AM EST SUN JAN 13 2013
NORTHWEST WINDS ARE EXPECTED TO REMAIN AT OR BELOW 25 KNOTS THROUGH
MONDAY AS HIGH PRESSURE GRADUALLY BUILDS FROM THE PLAINS TOWARD THE
GREAT LAKES. A CLIPPER LOW PRES SYSTEM MOVING INTO SRN MANITOBA
TUESDAY AND NORTHERN ONTARIO TUE NIGHT WILL LIKELY BRING SW GALES
ACROSS LAKE SUPERIOR. AS THE LOW DEEPENS AND MOVES TOWARD NRN QUEBEC
WED...SOME NW GALES MAY ALSO BE POSSIBLE.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
LAKE EFFECT SNOW ADVISORY FROM 1 PM THIS AFTERNOON TO 7 AM EST
MONDAY FOR MIZ006-007.
LAKE EFFECT SNOW ADVISORY UNTIL 7 AM EST MONDAY FOR MIZ002.
LAKE EFFECT SNOW ADVISORY UNTIL 7 PM EST MONDAY FOR MIZ001-003.
LAKE SUPERIOR...
NONE.
LAKE MICHIGAN...
NONE.
&&
$$
SHORT TERM...JLB
LONG TERM...SRF
AVIATION...JLB
MARINE...JLB
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
536 AM EST SUN JAN 13 2013
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 533 AM EST SUN JAN 13 2013
WV IMAGERY AND RUC ANALYSIS INDICATED A MID/UPPER LEVEL TROUGH FROM
CENTRAL CANADA THROUGH THE WRN PLAINS AND A RIDGE OFF THE EAST COAST
RESULTING IN SW FLOW FROM THE SRN PLAINS INTO THE GREAT LAKES. AN
UPSTREAM SHORTWAVE TROUGH WAS LOCATED OVER NEBRASKA. AT THE
SFC...THE MAIN TROUGH/FRONT AND FOCUS FOR HEAVIER PCPN WAS LOCATED WELL
TO THE SOUTH...FROM NW OH THROUGH WRN KY INTO NRN MS. TO THE
WEST...AN ARCTIC HIGH PRES RIDGE EXTENDED FROM ALBERTA/SASK INTO THE
WRN PLAINS. WITH MAINLY NW LOW LEVEL FLOW ACROSS THE NRN LAKES...LAKE
INDUCED TROUGHING HAS KEPT LOW LEVEL CONV FOCUSED NEAR THE LAKE FROM
IWD-P59. EVEN THOUGH 850 MB TEMPS TO AROUND -20C OVER WRN LAKE
SUPERIOR PROVIDED PLENTY OF INSTABILITY(LAKE INDUCED CAPE VALUES TO
AROUND 400 J/KG) LOW INVERSION HEIGHTS AROUND 4K FT WITH PROMINENT
MID LEVEL DRYING HAS LIMITED LES RATES WITH ONLY LIGHT ACCUMULATIONS
OF A FEW INCHES OVERNIGHT. THE DRY AIR...SLIGHTLY LOWER INVERSION
HEIGHTS AND 850 MB TEMPS ONLY NEAR -12C...HAS INHIBITED LES OVER THE
ERN LAKE.
MAIN FCST CONCERNS ARE LES TRENDS.
MODELS WERE CONSISTENT IN BRINGING THE NEBRASKA SHRTWV NORTHEAST
THROUGH THE WRN GREAT LAKES. EVEN WITH MODERATE TO STRONG 700-300 MB
QVECTOR CONV AHEAD OF THE SHRTWV...LITTLE SYNOPTIC PCPN IS EXPECTED
IN THE DRY AIRMASS TO THE NORTH OF THE MAIN FRONTAL BOUNDARY. SOME
LIGHT SNOW WILL BE POSSIBLE WITH THIS FEATURE WITH ANY ACCUMULATIONS
AMOUNTING TO TO A HALF INCH OR LESS.
THE MAIN IMPACT WILL BE TO INVIGORATE THE LES...ESPECIALLY LATE THIS
AFTERNOON AND EVENING...AS DEEPER MOISTURE MOVES IN AND INVERSION
HEIGHTS CLIMB AOA 7K FT WITH 850 MB TEMPS AROUND -19C. WITH THE DGZ IN
THE CONVECTIVE LAYER...SNOW/WATER RATIO VALUES SHOULD ALSO REMAIN
HIGH(FROM 25/1 TO 30/1). VEERING WINDS WILL SHIFT THE FOCUS OF THE
HEAVIER LES TO AREAS BTWN HOUGHTON AND THE PORCUPIN MOUNTAINS AND
ALSO WILL ALLOW THE LES TO PUSH INTO THE EAST (LOCATIONS FROM AU
TRAIN EASTWARD).
ONGOING ADVISORIES AND SNOWFALL AMOUNTS LOOK ON TRACK WITH 12 HOUR
AMOUNTS OF 1 TO 4 INCHES WEST TODAY AND 2 TO 5 INCHES TONIGHT. OVER
THE EAST...1 TO 3 INCHES ARE EXPECTED THIS AFTERNOON WITH AMOUNTS OF
3 TO 6 INCHES POSSIBLE...GREATEST NEAR THE LAKE EAST OF MUNISING.
SOME HIGHER AMOUNTS MAY BE POSSIBLE EAST IF A MORE DOMINANT BAND
DEVELOPS BUT CONFIDENCE IN THE LOCATION IS LIMITED GIVEN SIGNFICNAT
DIFFERENCES BETWEEN THE HIGHER RES MODELS.
.LONG TERM...(MONDAY THROUGH SATURDAY)
ISSUED AT 426 AM EST SUN JAN 13 2013
WEST TO NORTHWEST FLOW LAKE EFFECT WILL BE ONGOING AT THE START OF
THE LONG TERM PERIOD. BUT WITH THE SURFACE TROUGH OVER EASTERN LAKE
SUPERIOR DIMINISHING DURING THE MORNING DUE TO A HIGH PRESSURE
RIDGE MOVING THROUGH MN...EXPECT THE WINDS TO BACK THROUGH THE DAY
AND BE OUT OF THE WEST-SOUTHWEST BY 00Z TUESDAY. THIS WILL PUSH THE
LAKE EFFECT OFFSHORE OVER THE EAST BY EARLY AFTERNOON AND FOCUS THE
LAKE EFFECT OVER THE KEWEENAW PENINSULA OVER THE WEST. SINCE
INVERSION HEIGHTS ARE STILL IN THE 7-8KFT RANGE AND DELTA-T VALUES
ARE AROUND 22...CONDITIONS ARE FAVORABLE FOR MODERATE SNOW TO
CONTINUE ON MONDAY. WITH THE SOUTHERN EDGE OF THE LAKE EFFECT BAND
BEING AIDED BY ENHANCED CONVERGENCE FROM THE BACKING WINDS...THINK
THERE SHOULD BE AT LEAST ONE STRONGER BAND GRADUALLY DRIFTING NORTH
THROUGH NORTHERN HOUGHTON COUNTY DURING THE DAY. THE BIGGEST
CONCERN WILL BE THE NORTHWARD PUSH IN THE MORNING...WHICH THEN
STALLS IN THE AFTERNOON AS WHAT IS LEFT OF THE SURFACE TROUGH
STALLS OVER THE KEWEENAW. WHERE THIS BAND STALLS OR DOESN/T
STALL WILL DETERMINE SNOWFALL AMOUNTS. BUFKIT SOUNDINGS SHOWING
FAVORABLE CONDITIONS FOR VERY FLUFFY 30-1 SNOW RATIOS...AS THE BEST
OMEGA IS CENTERED RIGHT IN THE DGZ...MUCH OF THE CLOUD IS IN THE
DGZ...AND WIND SPEEDS ARE NOT OVERLY STRONG. WILL FOLLOW THAT IDEA
FOR THE FORECAST AND BUMP RATIOS TOWARDS THAT. WITH THE WAY MODELS
ARE LOOKING...COULD BE A PERIOD OF EVEN HEAVY SNOW DURING THE LATE
MORNING AND AFTERNOON HOURS...SINCE POCKET OF DEEPER H850-700
MOISTURE HELPS PUSH LAKE EFFECT SNOW PARAMETER VALUES WELL OVER 2.
HAVE FINE TUNED THE POPS DURING THIS PERIOD AND BUMPED SNOWFALL
AMOUNTS UP A FEW INCHES. 00Z RUNS OF BOTH THE NESTED 4KM NAM AND OUR
LOCAL WRF-ARW COBB SNOWFALL OUTPUT ARE INDICATING 10IN OF SNOW FOR
KCMX FROM 12Z MONDAY THROUGH 06Z TUESDAY. HAD SOME CONCERN EXTENDING
THE ADVISORY FOR ANOTHER 12HRS SINCE IT WAS A SIGNIFICANT JUMP FROM
PREVIOUS RUNS...BUT WITH GOING FORECAST VALUES OF 3-5 INCHES ON
MONDAY COULDN/T HOLD OFF ON IT.
WITH THE HIGH PRESSURE RIDGE SLIDING EAST ACROSS WISCONSIN ON
MONDAY NIGHT...INDICATIONS ARE THE WINDS BACKING MORE TO THE
SOUTHWEST. THIS WILL PUSH THE STRONGER SNOW TO THE NORTH THROUGH
KEWEENAW COUNTY AND BRING AN END TO THE LES FOR THE CWA FOR
A DAY OR TWO DUE TO H850 TEMPS WARMING TO -10C UNDER THE STRONG
SOUTHWESTERLY FLOW ON TUESDAY.
THIS INCREASING SOUTHWESTERLY FLOW IS IN RESPONSE TO AN APPROACHING
SHORTWAVE AND CLIPPER SYSTEM DROPPING THROUGH THE NORTHWEST FLOW
ALOFT. THIS COULD PRODUCE SOME BREEZY CONDITIONS ON TUESDAY
INTO TUESDAY NIGHT. BOTH NAM/GFS SHOWING H925 WINDS OF
40-50KTS...BUT A WEAK INVERSION MAY BE ENOUGH TO KEEP THAT
FROM REACHING THE SURFACE OVER LAND. OVER LAKE SUPERIOR...BUFKIT
SOUNDINGS SHOWING MUCH OF THAT REACHING THE SURFACE DUE TO STRONG
PRESSURE FALL /14MB IN 12HR/ MOVING ACROSS THE LAKE. THUS...HAVE
BUMPED WINDS UP A SOLID 10KTS TO GALES AND IF LATEST TRENDS ARE
CORRECT THEY WILL NEED TO GO ANOTHER 5-10KTS HIGHER. DEFINITELY
SEEING BETTER AGREEMENT IN THE MODELS WITH THE TIMING/TRACK OF THE
SYSTEM...ALTHOUGH THE ECMWF/GEM ARE A LITTLE FARTHER SOUTH AND
SLOWER WITH AN ELONGATED SURFACE TROUGH AS IT MOVES THROUGH LATE
TUESDAY NIGHT INTO WEDNESDAY. EITHER SOLUTION SHOULD LEAD TO AT
LEAST A DUSTING TO AN INCH OF SNOW CWA WIDE...BUT ECMWF/GEM COULD
PRODUCE SOME AREAS WITH A COUPLE INCHES OF SNOW.
COLD AIR WILL SURGE IN BEHIND THIS CLIPPER...AS THE POLAR VORTEX
DIVES SOUTHEAST TOWARDS JAMES BAY. AT THIS POINT IT LOOKS TO STAY
THERE...BUT IT WILL STILL LEAD TO H850 TEMPS IN THE LOW TO MID -20S.
WITH HIGH PRESSURE CENTERED IN THE CENTRAL PLAINS AND A LOW OVER
HUDSON BAY...EXPECT NORTHWESTERLY WINDS AT THE SURFACE AND THROUGH
H850. THIS WILL LEAD TO PERSISTENT LES IN THAT FAVORED WIND
DIRECTION WEDNESDAY NIGHT THROUGH THURSDAY NIGHT. WILL CONTINUE TO
HIGHLIGHT HIGH END LIKELY POPS IN THAT AREA. INTENSITY WILL DEPEND
ON THE INVERSION HEIGHTS AND IF ANY DEEPER MOISTURE OR SHORTWAVES
SWEEP THROUGH. 00Z GFS SHOWING LAKE INDUCED EQL HEIGHTS OF
7-9KFT...BUT MOISTURE REMAINS BELOW 5KFT WITH FORCING ON HIGHER
EDGE OF DGZ. THUS...POTENTIAL IS THERE FOR MODERATE SNOW...BUT
MOISTURE WILL BE CONTROLLING FACTOR.
GFS/ECMWF CONTINUING TO SHOW THE POTENTIAL FOR A WEAK SHORTWAVE
SLIDING THROUGH THE NORTHWEST FLOW ON FRIDAY AND AGAIN ON SATURDAY.
THIS LEADS TO SOME UNCERTAINTY IN THE LAKE EFFECT LOCATIONS AND
JUST LOW END CHANCE OR SLIGHT POPS ACROSS THE REST OF THE CWA.
AFTER A BELOW NORMAL START TO THE WORK WEEK...TEMPERATURES LOOK TO
RETURN TO NORMAL FOR TUESDAY/WEDNESDAY BEFORE FALLING 5-10 DEGREES
BELOW NORMAL FOR THE END OF THE WORK WEEK. FINALLY...00Z GFS HAS
TRENDED TOWARDS WHAT THE ECMWF HAS BEEN SHOWING WITH THE POLAR
VORTEX DIVING SOUTH INTO THE GREAT LAKES ON SUNDAY/MONDAY.
SIGNIFICANT DIFFERENCES IN THE AMOUNT OF COLD AIR BETWEEN THE
MODELS...SO IT WILL BE INTERESTING TO SEE WHICH ONE PANS OUT. IF
ECMWF IS RIGHT...H850 TEMPS WILL BE AROUND -35C AND WOULD LEAD TO
INLAND AREAS ON SLIGHTLY ABOVE ZERO FOR HIGHS.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SUNDAY NIGHT)
ISSUED AT 1213 AM EST SUN JAN 13 2013
EXPECT MVFR CONDITIONS TO PREVAIL AT CMX/IWD WITH SURGE OF COLD AIR
OVER THE RELATIVELY WARM WATERS OF LK SUP AND UPSLOPE W-NW WIND.
THERE COULD BE SOME HEAVIER SHSN/IFR CONDITIONS MAINLY AT CMX...
ESPECIALLY EARLY THIS MRNG WITH THE PASSAGE OF A LO PRES TROF. SINCE
THE W VEERING NW LLVL FLOW WL DOWNSLOPE AT SAW...EXPECT MVFR
CONDITIONS AT THAT LOCATION TO GIVE WAY TO VFR WX AT TIMES. THE
APPROACH OF ANOTHER DISTURBANCE LATER ON SUN WL INCREASE THE CHC OF
HEAVIER SHSN/IFR VSBYS AT IWD/CMX IN THE PRESENCE OF AN UPSLOPE
WIND. ALTHOUGH SOME -SHSN MAY IMPACT SAW AS WELL...DOWNSLOPE WIND WL
LIMIT THE POTENTIAL FOR ANY WORSE THAN MVFR CONDITIONS.
&&
.MARINE...(FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 533 AM EST SUN JAN 13 2013
NORTHWEST WINDS ARE EXPECTED TO REMAIN AT OR BELOW 25 KNOTS THROUGH
MONDAY AS HIGH PRESSURE GRADUALLY BUILDS FROM THE PLAINS TOWARD THE
GREAT LAKES. A CLIPPER LOW PRES SYSTEM MOVING INTO SRN MANITOBA
TUESDAY AND NORTHERN ONTARIO TUE NIGHT WILL LIKELY BRING SW GALES
ACROSS LAKE SUPERIOR. AS THE LOW DEEPENS AND MOVES TOWARD NRN QUEBEC
WED...SOME NW GALES MAY ALSO BE POSSIBLE.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
LAKE EFFECT SNOW ADVISORY FROM 1 PM THIS AFTERNOON TO 7 AM EST
MONDAY FOR MIZ006-007.
LAKE EFFECT SNOW ADVISORY UNTIL 7 AM EST MONDAY FOR MIZ002.
LAKE EFFECT SNOW ADVISORY UNTIL 7 PM EST MONDAY FOR MIZ001-003.
LAKE SUPERIOR...
NONE.
LAKE MICHIGAN...
NONE.
&&
$$
SHORT TERM...JLB
LONG TERM...SRF
AVIATION...KC
MARINE...JLB
AREA FORECAST DISCUSSION
NWS TWIN CITIES/CHANHASSEN MN
1137 AM CST SUN JAN 13 2013
.UPDATE...
UPDATED TO INCLUDE 18Z AVIATION DISCUSSION BELOW.
&&
.DISCUSSION...
/ISSUED 936 AM CST SUN JAN 13 2013/
RECENT RADAR AND SURFACE OBSERVATION TRENDS SHOW A NICE BLOSSOMING
OF LIGHT SNOW ACTIVITY AHEAD OF THE MID-LEVEL TROUGH CURRENTLY
PUSHING ACROSS THE AREA. THIS FEATURE SHOWS UP WELL ON WATER
VAPOR... AND THE RUC HIGHLIGHTS A TIGHT UPPER LEVEL PV GRADIENT
ASSOCIATED WITH IT. GIVEN DEEP LAYER SATURATION AND SOME MODEST
VERTICAL MOTION EXPECT TO SEE OCCASIONAL LIGHT SNOW PERSIST AS THE
SYSTEM MOVES ACROSS THE AREA THROUGH THE DAY. PRECIPITATION
AMOUNTS WILL BE LIMITED... AND DON/T EXPECT MUCH MORE THAN A
DUSTING OR FEW TENTHS OF ACCUMULATION... BUT GIVEN THE FACT THAT
WHITE FROZEN STUFF WILL FALL FROM THE SKY DECIDED TO BUMP POPS UP
INTO THE LIKELY TO CATEGORICAL RANGE FOR LIGHT SNOW.
&&
.AVIATION.../18Z TAF ISSUANCE/
DECENT UPPER LEVEL TROUGH CURRENTLY MOVING THROUGH THE AREA IS
GENERATING SOME LIGHT SNOW AND MAINLY MVFR VISIBILITIES UNDER MVFR
CEILINGS. THIS UPPER WAVE WILL CONTINUE TO PUSH EAST THROUGH THE
AFTERNOON AND EARLY EVENING WITH ANY PCPN ENDING... BUT SOME MID-
HIGH CLOUDS REMAINING. WINDS WILL BACK SLIGHTLY THROUGH MONDAY...
BUT REMAIN FAIRLY LIGHT WITH MINIMAL TO NON-EXISTENT GUSTINESS
EXPECTED. ANOTHER UPPER WAVE IS EXPECTED TO PUSH ACROSS THE AREA
ON MONDAY... WHICH COULD WRING OUT SOME SNOWFLAKES AND SUB-3KFT
CEILINGS ONCE AGAIN... BUT AT THIS POINT CONFIDENCE IS TOO LOW TO
INCLUDE MUCH OF ANYTHING WITH THAT.
KMSP...TAF REFLECTS EXPECTIONS WITH REASONABLY GOOD CONFIDENCE.
MAIN DIFFERENCES WOULD BE IN THE TIMING OF SNOW ENDING THIS
AFTERNOON WHICH COULD VARY BY +/- 1 HOUR.
/OUTLOOK FOR KMSP/
MONDAY NIGHT...OCCASIONAL MVFR CEILINGS POSSIBLE. SOUTHWEST WIND 5
TO 10 KT.
TUESDAY...VFR CONDITIONS EXPECTED. SOUTHWEST WIND INCREASING TO 10
TO 20 KT.
TUESDAY NIGHT...MVFR CEILINGS AND VISIBILITIES POSSIBLE LATE WITH
A CHANCE OF LIGHT SNOW. SOUTHWEST WIND 10 TO 20 KT WITH HIGH GUSTS
POSSIBLE LATE.
WEDNESDAY...MVFR CEILINGS AND VISIBILITIES POSSIBLE EARLY WITH A
CHANCE OF LIGHT SNOW. SOUTHWEST WIND 15 TO 25 KT WITH HIGHER GUSTS
SHIFTING WEST.
WEDNESDAY NIGHT...VFR CONDITIONS EXPECTED. NORTHWEST WIND 10 TO 20
KT.
&&
.PREV DISCUSSION...
/ISSUED 400 AM CST SUN JAN 13 2013/
A MID/UPPER LEVEL TROUGH FROM ONTARIO TO THE CENTRAL PLAINS WILL
MOVE SLOWLY ACROSS THE FA TODAY. CURRENTLY THE CENTER PORTION OF
THE CWA IS CLEAR. HOWEVER... MID LEVEL CLOUDINESS IS EXPANDING
OVER EASTERN SD AND NE. BOTH THE NAM AND GFS SHOW THIS CLOUDINESS
SPREADING ENE THROUGH THE MORNING... WITH PARTLY TO MOSTLY CLOUDY
CONDITIONS OCCURRING. KEPT A MENTION OF FLURRIES TO THE NORTH AND
EAST OF THE TWIN CITIES TODAY WHERE LOW LEVEL CLOUDINESS ALREADY
EXISTS. IT WILL BE A COLD DAY WITH HIGHS IN THE SINGLE DIGITS TO
TEENS. HIGH PRESSURE WILL BUILD IN FROM THE WEST TONIGHT WITH
CLEARING OCCURRING. LOWS ARE FORECAST FROM ZERO TO 10 BELOW.
THE WEEK AHEAD WILL FEATURE A SERIES OF ALBERTA CLIPPER LOW
PRESSURE SYSTEMS. TIMING AND LOCATION ARE IN PRETTY GOOD AGREEMENT
BETWEEN THE GFS AND ECMWF. THE FIRST WILL PASS ALONG OR JUST NORTH
OF THE INTERNATIONAL BORDER TUESDAY NIGHT AND EARLY WEDNESDAY.
THE SREF IS ALREADY SHOWING LIKELY TO CATEGORICAL POPS FOR THE
NORTHERN HALF OF MN AND WI. AT THIS POINT...BLENDED IN THE SREF
WHICH BROUGHT OUR POPS UP INTO THE HIGH CHANCE CATEGORY ACROSS
OUR FAR NORTHERN CWA. SOME LIGHT SNOW ACCUMULATION WOULD CERTAINLY
BE POSSIBLE ALONG AND NORTH OF I-94.
THE COLD FRONT TRAILING THE LOW WILL MOVE THROUGH LATE ON
WEDNESDAY. THIS ALLOWS ANOTHER WEAK LOW TO MOVE ALONG THIS
BOUNDARY THURSDAY NIGHT AND FRIDAY. THIS EVENT IS AGAIN MAINLY
ALONG AND NORTH OF I-94...BUT IT DOES HAVE THE POSSIBILITY OF
GETTING DOWN INTO THE TWIN CITIES FOR THE FRIDAY MORNING COMMUTE
AND WILL NEED TO BE WATCHED.
FINALLY...ANOTHER LOW WILL PASS ALONG THE INTERNATIONAL BORDER
FRIDAY NIGHT AND SATURDAY WITH A PRECIPITATION PATTERN EXPECTED
MUCH LIKE THE TUESDAY NIGHT/WEDNESDAY ONE. ONE THING NOTED IS THAT
THERE WILL BE A PRETTY WARM WESTERLY FLOW ACROSS SOUTHERN MN AND
INTO WI WITH THE SATURDAY LOW PRESSURE SYSTEM AND HIGH
TEMPERATURES IN THE 25 TO 30 DEGREE RANGE MAY NOT BE WARM
ENOUGH...ESPECIALLY WHEN COMPARING THE LOW LEVEL THERMAL PATTERN
FOR WEDNESDAY WITH 35 TO 40 DEGREE TEMPERATURES PROGGED.
IT DOES APPEAR THAT IN THE WAKE OF NEXT WEEKENDS LOW PRESSURE
SYSTEM...THE FLOW PATTERN ALOFT WILL TURN NORTHERLY. THIS COULD
UNLEASH THE COLDEST AIR YET THIS WINTER. ITS POSSIBLE WE COULD SEE
A DAY OR TWO WHERE THE HIGH FAILS TO GET ABOVE ZERO...ESPECIALLY
ACROSS THE CENTRAL AND NORTH WHERE A BETTER SNOWPACK STILL EXISTS
AND MORE COULD BE ADDED THIS WEEK. THIS COULD ALSO JEOPARDIZE THE
RECORD HERE AT MSP WHERE CONSECUTIVE DAYS WITH HIGHS OF ZERO OR
GREATER HAVE OCCURRED FOR NEARLY 4 YEARS.
&&
.MPX WATCHES/WARNINGS/ADVISORIES...
MN...NONE.
WI...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS TWIN CITIES/CHANHASSEN MN
936 AM CST SUN JAN 13 2013
.DISCUSSION...
RECENT RADAR AND SURFACE OBSERVATION TRENDS SHOW A NICE BLOSSOMING
OF LIGHT SNOW ACTIVITY AHEAD OF THE MID-LEVEL TROUGH CURRENTLY
PUSHING ACROSS THE AREA. THIS FEATURE SHOWS UP WELL ON WATER
VAPOR... AND THE RUC HIGHLIGHTS A TIGHT UPPER LEVEL PV GRADIENT
ASSOCIATED WITH IT. GIVEN DEEP LAYER SATURATION AND SOME MODEST
VERTICAL MOTION EXPECT TO SEE OCCASIONAL LIGHT SNOW PERSIST AS THE
SYSTEM MOVES ACROSS THE AREA THROUGH THE DAY. PRECIPITATION
AMOUNTS WILL BE LIMITED... AND DON/T EXPECT MUCH MORE THAN A
DUSTING OR FEW TENTHS OF ACCUMULATION... BUT GIVEN THE FACT THAT
WHITE FROZEN STUFF WILL FALL FROM THE SKY DECIDED TO BUMP POPS UP
INTO THE LIKELY TO CATEGORICAL RANGE FOR LIGHT SNOW.
&&
.AVIATION.../12Z TAF ISSUANCE/
/ISSUED 503 AM CST SUN JAN 13 2013/
MAIN AVIATION CONCERN DEALS WITH MVFR CIGS AS BOUNDARY LAYER
MOISTURE...UP TO 70H IS RATHER HIGH...AND WITH THE TYPICAL DIURNAL
HEATING...WILL LIFT ANY MOISTURE TO THE LCL/S WHICH MEANS CIGS
DEVELOPING ARND 2-3K. IN ADDITION...MID LEVEL MOISTURE AND A
DISTURBANCE RIDING NE ACROSS IA WILL ENHANCE SOME LIFT ACROSS
EASTERN MN DURING THE DAY. SO...-SN REMAINS POSSIBLE BUT VSBYS
SHOULD NOT DROP BELOW MVFR AS ACTIVITY SHOULD BE ISOLATED. ANOTHER
AREA OF MVFR CIGS COULD BEGIN TO AFFECT THE TAFS AFT 6Z/14. WINDS
WILL REMAIN FROM THE NW/WNW THRU THE PERIOD WITH SPDS ARND 8-11
KTS TODAY...DROPPING OFF TO 4-6 KTS OVERNIGHT.
KMSP...
MVFR CIGS NEAR THE AIRPORT TERMINAL...BUT NOT WIDESPREAD ENOUGH TO
WARRANT IN CURRENT TAF...AT LEAST NOT UNTIL 15-16Z AS CIGS LOWER
TO 2.5K ALONG WITH -SN. BEST TIME PERIOD FOR FLURRIES WILL OCCUR
AFT 16Z...AND MAY LAST UNTIL 21-22Z. VFR CONDS SHOULD PREVAIL AFT
22Z...WITH SOME CONCERNS LATE IN THE TAF PERIOD OF MVFR CIGS
RETURNING AFT 6Z/14. WINDS WILL REMAIN FROM THE NW...THEN MORE WNW
OVERNIGHT. SPDS WILL BE ARND 8-10 KTS TODAY...DROPPING TO 4-7KTS
OVERNIGHT.
/OUTLOOK FOR KMSP/
MON...POSSIBLE MVFR CIGS EARLY. WINDS W 5-10 KTS.
TUE...VFR. WINDS SW AROUND 10 KTS...INCREASING TO 15-20 KTS TUE NIGHT.
WED...CHANCE MVFR OR LOWER CIGS/VIS WITH -SN. WINDS W 10G20KTS.
&&
.PREV DISCUSSION...
/ISSUED 400 AM CST SUN JAN 13 2013/
A MID/UPPER LEVEL TROUGH FROM ONTARIO TO THE CENTRAL PLAINS WILL
MOVE SLOWLY ACROSS THE FA TODAY. CURRENTLY THE CENTER PORTION OF
THE CWA IS CLEAR. HOWEVER... MID LEVEL CLOUDINESS IS EXPANDING
OVER EASTERN SD AND NE. BOTH THE NAM AND GFS SHOW THIS CLOUDINESS
SPREADING ENE THROUGH THE MORNING... WITH PARTLY TO MOSTLY CLOUDY
CONDITIONS OCCURRING. KEPT A MENTION OF FLURRIES TO THE NORTH AND
EAST OF THE TWIN CITIES TODAY WHERE LOW LEVEL CLOUDINESS ALREADY
EXISTS. IT WILL BE A COLD DAY WITH HIGHS IN THE SINGLE DIGITS TO
TEENS. HIGH PRESSURE WILL BUILD IN FROM THE WEST TONIGHT WITH
CLEARING OCCURRING. LOWS ARE FORECAST FROM ZERO TO 10 BELOW.
THE WEEK AHEAD WILL FEATURE A SERIES OF ALBERTA CLIPPER LOW
PRESSURE SYSTEMS. TIMING AND LOCATION ARE IN PRETTY GOOD AGREEMENT
BETWEEN THE GFS AND ECMWF. THE FIRST WILL PASS ALONG OR JUST NORTH
OF THE INTERNATIONAL BORDER TUESDAY NIGHT AND EARLY WEDNESDAY.
THE SREF IS ALREADY SHOWING LIKELY TO CATEGORICAL POPS FOR THE
NORTHERN HALF OF MN AND WI. AT THIS POINT...BLENDED IN THE SREF
WHICH BROUGHT OUR POPS UP INTO THE HIGH CHANCE CATEGORY ACROSS
OUR FAR NORTHERN CWA. SOME LIGHT SNOW ACCUMULATION WOULD CERTAINLY
BE POSSIBLE ALONG AND NORTH OF I-94.
THE COLD FRONT TRAILING THE LOW WILL MOVE THROUGH LATE ON
WEDNESDAY. THIS ALLOWS ANOTHER WEAK LOW TO MOVE ALONG THIS
BOUNDARY THURSDAY NIGHT AND FRIDAY. THIS EVENT IS AGAIN MAINLY
ALONG AND NORTH OF I-94...BUT IT DOES HAVE THE POSSIBILITY OF
GETTING DOWN INTO THE TWIN CITIES FOR THE FRIDAY MORNING COMMUTE
AND WILL NEED TO BE WATCHED.
FINALLY...ANOTHER LOW WILL PASS ALONG THE INTERNATIONAL BORDER
FRIDAY NIGHT AND SATURDAY WITH A PRECIPITATION PATTERN EXPECTED
MUCH LIKE THE TUESDAY NIGHT/WEDNESDAY ONE. ONE THING NOTED IS THAT
THERE WILL BE A PRETTY WARM WESTERLY FLOW ACROSS SOUTHERN MN AND
INTO WI WITH THE SATURDAY LOW PRESSURE SYSTEM AND HIGH
TEMPERATURES IN THE 25 TO 30 DEGREE RANGE MAY NOT BE WARM
ENOUGH...ESPECIALLY WHEN COMPARING THE LOW LEVEL THERMAL PATTERN
FOR WEDNESDAY WITH 35 TO 40 DEGREE TEMPERATURES PROGGED.
IT DOES APPEAR THAT IN THE WAKE OF NEXT WEEKENDS LOW PRESSURE
SYSTEM...THE FLOW PATTERN ALOFT WILL TURN NORTHERLY. THIS COULD
UNLEASH THE COLDEST AIR YET THIS WINTER. ITS POSSIBLE WE COULD SEE
A DAY OR TWO WHERE THE HIGH FAILS TO GET ABOVE ZERO...ESPECIALLY
ACROSS THE CENTRAL AND NORTH WHERE A BETTER SNOW-PACK STILL EXISTS
AND MORE COULD BE ADDED THIS WEEK. THIS COULD ALSO JEOPARDIZE THE
RECORD HERE AT MSP WHERE CONSECUTIVE DAYS WITH HIGHS OF ZERO OR
GREATER HAVE OCCURRED FOR NEARLY 4 YEARS.
&&
.MPX WATCHES/WARNINGS/ADVISORIES...
MN...NONE.
WI...NONE.
&&
$$
AREA FORECAST DISCUSSION...UPDATED AVIATION
NWS ST LOUIS MO
1144 AM CST SUN JAN 13 2013
.SHORT TERM...
ISSUED AT 502 AM CST SUN JAN 13 2013
(TODAY)
THERE ARE TWO MAIN AREAS OF CONCERN WRT PCPN TODAY. THE FIRST IS
NEAR THE FNTL BDRY WHICH MOVED THROUGH THE CWA YESTERDAY AND THE
SECOND IS AN AREA OF FRONTOGENESIS ALONG THE VERTICALLY SLOPED
FRONTAL SFC WHICH IS FCST TO MOVE THROUGH THE CWA TODAY.
A VORT MAX IN THE BASE OF THE LONGWAVE TROF OVER OK/TX IS FCST TO
LIFT NEWD INTO WISCONSIN TODAY WHICH WILL PROVIDE A SOURCE OF LARGE
SCALE LIFT ACROSS THE AREA AS SEEN ON H7-H5 QVECTOR CONVERGENCE
GRAPHICS. A STRONG CDFNT WAS LOCATED SOUTHEAST OF THE CWA EARLY
THIS MORNING AND A SFC WAVE RIDING ALONG THE BDRY OVERNIGHT HAD
PUSHED IT EVEN FARTHER TO THE SOUTHEAST. WIDESPREAD PCPN WAS ALSO
OCCURRING ALONG THE FRONT EARLY THIS MORNING. ANOTHER SFC WAVE IS
FCST TO RIDE NEWD ALONG THE BAROCLINIC ZONE TODAY AND SOME OF THE
FNTL PCPN COULD SPILL OVER INTO THE SERN AND ERN CWA
TODAY...ESPECIALLY IF A PORTION OF THE SFC BDRY LIFTS SLIGHTLY
NWWD AHEAD OF THE SFC WAVE. THE CONCERN HERE IS THAT TEMPERATURE
PROFILES WOULD SUPPORT FREEZING RAIN OVER THIS AREA. THERE ARE NO
STRONG SIGNALS IN THE MODELS TO SUPPORT SUCH A NWWD WOBBLE BUT IF
IT DOES OCCUR OR IF SCT SHRA /SIMILAR TO WHAT WAS OCCURRING OVER
AR BETWEEN 10-11Z/ EXPANDS IN COVERAGE THEN LATER SHIFTS MAY NEED
TO CONSIDER A FREEZING RAIN ADVISORY FOR PARTS OF THE SERN/ERN
CWA.
THE SECOND AREA OF CONCERN WAS A BAND OF FRONTOGENETICALLY FORCED
PCPN OVER NERN OK/SERN KS/WRN MO WHICH APPEARED TO BE OCCURRING
ALONG THE H85-H7 FRONTAL SFC BASED ON THE 09Z RUC ANALYSIS. THIS
AREA OF FORCING IS EXPECTED TO EXPAND/MOVE ACROSS THE CWA TODAY
WITH THE LIFTING VORT MAX AND COULD RESULT IN LIGHT SNOW OR LIGHT
FREEZING RAIN/DRIZZLE SINCE THE FCST FORCING AND MOISTURE OVER OUR
AREA LATER TODAY BOTH LOOK COMPARABLE TO WHAT WAS ALREADY
OCCURRING OVER OK BETWEEN 09-11Z. IN SUMMARY...THE GREATEST
POTENTIAL FOR MEASURABLE -FZRA IS OVER THE SERN/ERN CWA AND A
TRACE OF GLAZING IS POSSIBLE ELSEWHERE. WE WILL ISSUE AN SPS TO
HIGHLIGHT THE POTENTIAL FOR A LIGHT GLAZE SINCE EVEN TRACE AMOUNTS
OF FREEZING RAIN/DRIZZLE CAN BE HAZARDOUS.
TEMPERATURES WILL PROBABLY STRUGGLE TO RISE MUCH ABOVE FREEZING
TODAY IN MOST LOCATIONS DUE TO THE COLD AIR MASS IN PLACE AND
WIDESPREAD CLOUDINESS DURING MOST OF THE DAYLIGHT HOURS.
KANOFSKY
&&
.LONG TERM...
ISSUED AT 210 AM CST SUN JAN 13 2013
(TONIGHT - TUESDAY NIGHT)
SW UPPER LEVEL FLOW WILL PREVAIL ACROSS THE REGION DURING THIS TIME
WITH A WEAK UPPER LEVEL DISTURBANCE MOVING THRU MONDAY AND THE
HEAVILY SHEARED REMNANTS FROM THE LONGWAVE TROF BASE ON TUESDAY AND
TUESDAY NIGHT. WHILE THIS PATTERN ALONE MAY TRY TO GIVE THE
SEMBLANCE OF AN ACTIVE PATTERN WITH ADDITIONAL CHANCES FOR PCPN...
THE SFC PATTERN WILL ALL BUT SQUASH THAT...WITH HI PRES DOMINATING
UNDERNEATH AND MAINTAINING VERY DRY AIR THRU THE COLUMN.
THE SFC HI THAT WILL DOMINATE THIS PERIOD WILL ALSO KEEP US BELOW
AVERAGE...ABOUT 10 DEGREES BELOW ON MONDAY AND 5 DEGREES BELOW ON
TUESDAY...AS THE AIRMASS SLOWLY MODERATES. MOS LOOKS A BIT TOO COLD
FOR MAXES BOTH DAYS...PERHAPS FROM OVERESTIMATING/ANTICIPATING SNOW
COVER FROM YESTERDAY/S SYSTEM...AND LEANED WARM VERSUS THEM.
(WEDNESDAY - SATURDAY)
A BIT OF A PATTERN SHIFT OF SOME NOTE OCCURS EARLY IN THIS PERIOD
WITH LONGWAVE TROF SHIFTING TO THE ERN CONUS...ALBEIT NOT QUITE WHAT
IT WAS WHEN IT WAS OVER THE W...AND IS ANTICIPATED TO BE GREATLY
DE-AMPLIFIED. THIS WILL GIVE US A W-NW FLOW AND IS EXPECTED TO BE
MARKED BY LITTLE OR NO WX-MAKING DISTURBANCES OF NOTE AND TEMPS AT
OR ABOVE AVERAGE.
ONCE WE GET IN THIS PATTERN...IT LOOKS LIKE IT WILL STAY FOR A WHILE
AS VERY LATE IN THIS PERIOD AMPLIFICATION OF THE RIDGE WILL TAKE
PLACE OVER THE WRN CONUS AND THIS WILL CAUSE A CORRESPONDING
DEEPENING OF THE TROF IN THE E. IF THIS HOLDS...SEVERAL WAVES OF
NOTABLE COLD COULD COME OUT OF THIS. BUT IF YOU ARE LOOKING FOR
SNOW...SYSTEMS TO TAKE ADVANTAGE OF THIS APPEAR SCARCE.
TES
&&
.AVIATION...
ISSUED AT 1134 AM CST SUN JAN 13 2013
STORM SYSTEM IS PULLING AWAY FROM THE AREA THIS AFTERNOON...BUT
THERE`S STILL SOME LINGERING AVIATION CONCERNS ESPECIALLY OVER
SOUTH CENTRAL ILLINOIS. EXPECT PRIMARILY MVFR FLIGHT CONDITIONS TO
PREVAIL EXCEPT OVER SOUTH CENTRAL ILLINOIS WHERE IFR CIGS/VSBYS
WILL CONTINUE UNTIL 20-21Z. PERIODS OF SLEET AND/OR FREEZING RAIN
WILL CONTINUE IN THOSE AREAS AS WELL WHICH WILL LIKELY CAUSE LIGHT
ICING ON ELEVATED SURFACES. ONCE THIS PRECIP CLEARS THE AREA
SHOULD SEE CONDITIONS IMPROVE TO MVFR. CIGS WILL CLEAR THE AREA
FROM WEST TO EAST LATE THIS AFTERNOON AND OVERNIGHT AS HIGH
PRESSURE BUILDS ACROSS THE AREA. VFR FLIGHT CONDITIONS ARE
EXPECTED AS THE HIGH BUILDS OVERHEAD.
SPECIFICS FOR KSTL...
LOOKS LIKE PRECIPITATION IS ABOUT DONE AT LAMBERT. CAN`T RULE OUT
AN OCCASIONAL ICE PELLET OR SNOW GRAIN AS THE STORM SYSTEM
CONTINUES PULLING EASTWARD...BUT RADAR ISN`T SHOWING ANY
SIGNIFICANT PRECIP SOUTHWEST OF THE TERMINAL. MVFR CIGS WILL
LIKELY PREVAIL THROUGH THE AFTERNOON INTO EARLY EVENING. UNSURE AT
THIS TIME EXACTLY WHEN THE CIGS WILL SCATTER AND CLEAR OUT...BUT
IT LOOKS LIKE MID TO LATE EVENING AT THIS TIME. VFR CONDITIONS ARE
EXPECTED TO PREVAIL AFTER THE CIGS CLEAR AS A STRONG SURFACE HIGH
BUILDS ACROSS THE REGION.
CARNEY
&&
.LSX WATCHES/WARNINGS/ADVISORIES...
MO...NONE.
IL...NONE.
&&
$$
WFO LSX
AREA FORECAST DISCUSSION...UPDATED AVIATION
NWS ST LOUIS MO
556 AM CST SUN JAN 13 2013
.SHORT TERM...
ISSUED AT 502 AM CST SUN JAN 13 2013
(TODAY)
THERE ARE TWO MAIN AREAS OF CONCERN WRT PCPN TODAY. THE FIRST IS
NEAR THE FNTL BDRY WHICH MOVED THROUGH THE CWA YESTERDAY AND THE
SECOND IS AN AREA OF FRONTOGENESIS ALONG THE VERTICALLY SLOPED
FRONTAL SFC WHICH IS FCST TO MOVE THROUGH THE CWA TODAY.
A VORT MAX IN THE BASE OF THE LONGWAVE TROF OVER OK/TX IS FCST TO
LIFT NEWD INTO WISCONSIN TODAY WHICH WILL PROVIDE A SOURCE OF LARGE
SCALE LIFT ACROSS THE AREA AS SEEN ON H7-H5 QVECTOR CONVERGENCE
GRAPHICS. A STRONG CDFNT WAS LOCATED SOUTHEAST OF THE CWA EARLY
THIS MORNING AND A SFC WAVE RIDING ALONG THE BDRY OVERNIGHT HAD
PUSHED IT EVEN FARTHER TO THE SOUTHEAST. WIDESPREAD PCPN WAS ALSO
OCCURRING ALONG THE FRONT EARLY THIS MORNING. ANOTHER SFC WAVE IS
FCST TO RIDE NEWD ALONG THE BAROCLINIC ZONE TODAY AND SOME OF THE
FNTL PCPN COULD SPILL OVER INTO THE SERN AND ERN CWA
TODAY...ESPECIALLY IF A PORTION OF THE SFC BDRY LIFTS SLIGHTLY
NWWD AHEAD OF THE SFC WAVE. THE CONCERN HERE IS THAT TEMPERATURE
PROFILES WOULD SUPPORT FREEZING RAIN OVER THIS AREA. THERE ARE NO
STRONG SIGNALS IN THE MODELS TO SUPPORT SUCH A NWWD WOBBLE BUT IF
IT DOES OCCUR OR IF SCT SHRA /SIMILAR TO WHAT WAS OCCURRING OVER
AR BETWEEN 10-11Z/ EXPANDS IN COVERAGE THEN LATER SHIFTS MAY NEED
TO CONSIDER A FREEZING RAIN ADVISORY FOR PARTS OF THE SERN/ERN
CWA.
THE SECOND AREA OF CONCERN WAS A BAND OF FRONTOGENETICALLY FORCED
PCPN OVER NERN OK/SERN KS/WRN MO WHICH APPEARED TO BE OCCURRING
ALONG THE H85-H7 FRONTAL SFC BASED ON THE 09Z RUC ANALYSIS. THIS
AREA OF FORCING IS EXPECTED TO EXPAND/MOVE ACROSS THE CWA TODAY
WITH THE LIFTING VORT MAX AND COULD RESULT IN LIGHT SNOW OR LIGHT
FREEZING RAIN/DRIZZLE SINCE THE FCST FORCING AND MOISTURE OVER OUR
AREA LATER TODAY BOTH LOOK COMPARABLE TO WHAT WAS ALREADY
OCCURRING OVER OK BETWEEN 09-11Z. IN SUMMARY...THE GREATEST
POTENTIAL FOR MEASURABLE -FZRA IS OVER THE SERN/ERN CWA AND A
TRACE OF GLAZING IS POSSIBLE ELSEWHERE. WE WILL ISSUE AN SPS TO
HIGHLIGHT THE POTENTIAL FOR A LIGHT GLAZE SINCE EVEN TRACE AMOUNTS
OF FREEZING RAIN/DRIZZLE CAN BE HAZARDOUS.
TEMPERATURES WILL PROBABLY STRUGGLE TO RISE MUCH ABOVE FREEZING
TODAY IN MOST LOCATIONS DUE TO THE COLD AIR MASS IN PLACE AND
WIDESPREAD CLOUDINESS DURING MOST OF THE DAYLIGHT HOURS.
KANOFSKY
&&
.LONG TERM...
ISSUED AT 210 AM CST SUN JAN 13 2013
(TONIGHT - TUESDAY NIGHT)
SW UPPER LEVEL FLOW WILL PREVAIL ACROSS THE REGION DURING THIS TIME
WITH A WEAK UPPER LEVEL DISTURBANCE MOVING THRU MONDAY AND THE
HEAVILY SHEARED REMNANTS FROM THE LONGWAVE TROF BASE ON TUESDAY AND
TUESDAY NIGHT. WHILE THIS PATTERN ALONE MAY TRY TO GIVE THE
SEMBLANCE OF AN ACTIVE PATTERN WITH ADDITIONAL CHANCES FOR PCPN...
THE SFC PATTERN WILL ALL BUT SQUASH THAT...WITH HI PRES DOMINATING
UNDERNEATH AND MAINTAINING VERY DRY AIR THRU THE COLUMN.
THE SFC HI THAT WILL DOMINATE THIS PERIOD WILL ALSO KEEP US BELOW
AVERAGE...ABOUT 10 DEGREES BELOW ON MONDAY AND 5 DEGREES BELOW ON
TUESDAY...AS THE AIRMASS SLOWLY MODERATES. MOS LOOKS A BIT TOO COLD
FOR MAXES BOTH DAYS...PERHAPS FROM OVERESTIMATING/ANTICIPATING SNOW
COVER FROM YESTERDAY/S SYSTEM...AND LEANED WARM VERSUS THEM.
(WEDNESDAY - SATURDAY)
A BIT OF A PATTERN SHIFT OF SOME NOTE OCCURS EARLY IN THIS PERIOD
WITH LONGWAVE TROF SHIFTING TO THE ERN CONUS...ALBEIT NOT QUITE WHAT
IT WAS WHEN IT WAS OVER THE W...AND IS ANTICIPATED TO BE GREATLY
DE-AMPLIFIED. THIS WILL GIVE US A W-NW FLOW AND IS EXPECTED TO BE
MARKED BY LITTLE OR NO WX-MAKING DISTURBANCES OF NOTE AND TEMPS AT
OR ABOVE AVERAGE.
ONCE WE GET IN THIS PATTERN...IT LOOKS LIKE IT WILL STAY FOR A WHILE
AS VERY LATE IN THIS PERIOD AMPLIFICATION OF THE RIDGE WILL TAKE
PLACE OVER THE WRN CONUS AND THIS WILL CAUSE A CORRESPONDING
DEEPENING OF THE TROF IN THE E. IF THIS HOLDS...SEVERAL WAVES OF
NOTABLE COLD COULD COME OUT OF THIS. BUT IF YOU ARE LOOKING FOR
SNOW...SYSTEMS TO TAKE ADVANTAGE OF THIS APPEAR SCARCE.
TES
&&
.AVIATION...
ISSUED AT 534 AM CST SUN JAN 13 2013
MVFR CIGS WILL GRADUALLY RISE THROUGH THE DAY WITH VFR CONDITIONS
EXPECTED BY EARLY EVENING. THE EXCEPTION TO THE OVERALL
IMPROVING TREND IS A BAND OF LIGHT TO MODERATE SNOW WHICH HAS
DVLPD OVER SWRN AND CENTRAL MO. IT LOOKS LIKE THIS BAND WILL REACH
KCOU/KUIN WITHIN THE NEXT FEW HOURS. IT IS NOT YET CLEAR IF THE
BAND WILL REACH KSUS/KCPS. EXPECT AROUND AN HOUR OF LIGHT TO
MODERATE SNOW WITH MVFR TO IFR VSBYS IF THE BAND MOVES OVER ONE OF
THE TERMINALS.
SPECIFICS FOR KSTL...MVFR CIGS ARE EXPECTED TO PERSIST FOR MOST OF
THE DAY BEFORE CLEARING LATE THIS AFTN OR EARLY THIS EVENING.
THERE COULD BE A BRIEF PD OF FREEZING DRIZZLE OR SNOW AT KSTL
TODAY BUT CONFIDENCE WAS TOO LOW TO INCLUDE A MENTION OF EITHER
PTYPE IN THE 12Z TAF. PCPN CHCS ARE TIED TO BOTH THE BAND OF SNOW
THAT WAS OVER SWRN/CENTRAL MO AT 12Z AND THE BROAD AREA OF
RAINFALL THAT WAS LOCATED ACROSS SERN MO NEAR A STRONG COLD
FRONT. MOST OF THE PCPN ASSOCIATED WITH THE COLD FRONT SHOULD
REMAIN WELL TO THE SOUTH AND EAST OF KSTL BUT SCT SHRA HAVE
RECENTLY DEVELOPED OVER ARKANSAS AND WERE MOVING NEWD. BUFKIT
PROFILES SUPPORT FREEZING DRIZZLE/RAIN IF THESE SHOWERS WERE TO
REACH KSTL. AS FOR THE SNOW...IT IS NOT YET CLEAR WHETHER THE BAND
OF SNOW IN SWRN/CENTRAL MO WILL REACH KSTL. IF IT DOES THEN THERE
WOULD BE AROUND AN HOUR OF LIGHT TO MODERATE SNOW WITH MVFR TO IFR
VSBYS BASED ON UPSTREAM OBS.
KANOFSKY
&&
.PRELIMINARY POINT TEMPS/POPS...
ST LOUIS 29 16 29 18 / 20 0 0 0
QUINCY 25 10 26 13 / 10 0 0 0
COLUMBIA 26 11 29 14 / 10 0 0 0
JEFFERSON CITY 28 11 29 14 / 10 0 0 0
SALEM 33 15 30 17 / 40 5 5 0
FARMINGTON 32 14 32 15 / 20 0 5 0
&&
.LSX WATCHES/WARNINGS/ADVISORIES...
MO...NONE.
IL...NONE.
&&
$$
WFO LSX
AREA FORECAST DISCUSSION
NWS ST LOUIS MO
506 AM CST SUN JAN 13 2013
.SHORT TERM...
ISSUED AT 502 AM CST SUN JAN 13 2013
(TODAY)
THERE ARE TWO MAIN AREAS OF CONCERN WRT PCPN TODAY. THE FIRST IS
NEAR THE FNTL BDRY WHICH MOVED THROUGH THE CWA YESTERDAY AND THE
SECOND IS AN AREA OF FRONTOGENESIS ALONG THE VERTICALLY SLOPED
FRONTAL SFC WHICH IS FCST TO MOVE THROUGH THE CWA TODAY.
A VORT MAX IN THE BASE OF THE LONGWAVE TROF OVER OK/TX IS FCST TO
LIFT NEWD INTO WISCONSIN TODAY WHICH WILL PROVIDE A SOURCE OF LARGE
SCALE LIFT ACROSS THE AREA AS SEEN ON H7-H5 QVECTOR CONVERGENCE
GRAPHICS. A STRONG CDFNT WAS LOCATED SOUTHEAST OF THE CWA EARLY
THIS MORNING AND A SFC WAVE RIDING ALONG THE BDRY OVERNIGHT HAD
PUSHED IT EVEN FARTHER TO THE SOUTHEAST. WIDESPREAD PCPN WAS ALSO
OCCURRING ALONG THE FRONT EARLY THIS MORNING. ANOTHER SFC WAVE IS
FCST TO RIDE NEWD ALONG THE BAROCLINIC ZONE TODAY AND SOME OF THE
FNTL PCPN COULD SPILL OVER INTO THE SERN AND ERN CWA
TODAY...ESPECIALLY IF A PORTION OF THE SFC BDRY LIFTS SLIGHTLY
NWWD AHEAD OF THE SFC WAVE. THE CONCERN HERE IS THAT TEMPERATURE
PROFILES WOULD SUPPORT FREEZING RAIN OVER THIS AREA. THERE ARE NO
STRONG SIGNALS IN THE MODELS TO SUPPORT SUCH A NWWD WOBBLE BUT IF
IT DOES OCCUR OR IF SCT SHRA /SIMILAR TO WHAT WAS OCCURRING OVER
AR BETWEEN 10-11Z/ EXPANDS IN COVERAGE THEN LATER SHIFTS MAY NEED
TO CONSIDER A FREEZING RAIN ADVISORY FOR PARTS OF THE SERN/ERN
CWA.
THE SECOND AREA OF CONCERN WAS A BAND OF FRONTOGENETICALLY FORCED
PCPN OVER NERN OK/SERN KS/WRN MO WHICH APPEARED TO BE OCCURRING
ALONG THE H85-H7 FRONTAL SFC BASED ON THE 09Z RUC ANALYSIS. THIS
AREA OF FORCING IS EXPECTED TO EXPAND/MOVE ACROSS THE CWA TODAY
WITH THE LIFTING VORT MAX AND COULD RESULT IN LIGHT SNOW OR LIGHT
FREEZING RAIN/DRIZZLE SINCE THE FCST FORCING AND MOISTURE OVER OUR
AREA LATER TODAY BOTH LOOK COMPARABLE TO WHAT WAS ALREADY
OCCURRING OVER OK BETWEEN 09-11Z. IN SUMMARY...THE GREATEST
POTENTIAL FOR MEASURABLE -FZRA IS OVER THE SERN/ERN CWA AND A
TRACE OF GLAZING IS POSSIBLE ELSEWHERE. WE WILL ISSUE AN SPS TO
HIGHLIGHT THE POTENTIAL FOR A LIGHT GLAZE SINCE EVEN TRACE AMOUNTS
OF FREEZING RAIN/DRIZZLE CAN BE HAZARDOUS.
TEMPERATURES WILL PROBABLY STRUGGLE TO RISE MUCH ABOVE FREEZING
TODAY IN MOST LOCATIONS DUE TO THE COLD AIR MASS IN PLACE AND
WIDESPREAD CLOUDINESS DURING MOST OF THE DAYLIGHT HOURS.
KANOFSKY
&&
.LONG TERM...
ISSUED AT 210 AM CST SUN JAN 13 2013
(TONIGHT - TUESDAY NIGHT)
SW UPPER LEVEL FLOW WILL PREVAIL ACROSS THE REGION DURING THIS TIME
WITH A WEAK UPPER LEVEL DISTURBANCE MOVING THRU MONDAY AND THE
HEAVILY SHEARED REMNANTS FROM THE LONGWAVE TROF BASE ON TUESDAY AND
TUESDAY NIGHT. WHILE THIS PATTERN ALONE MAY TRY TO GIVE THE
SEMBLANCE OF AN ACTIVE PATTERN WITH ADDITIONAL CHANCES FOR PCPN...
THE SFC PATTERN WILL ALL BUT SQUASH THAT...WITH HI PRES DOMINATING
UNDERNEATH AND MAINTAINING VERY DRY AIR THRU THE COLUMN.
THE SFC HI THAT WILL DOMINATE THIS PERIOD WILL ALSO KEEP US BELOW
AVERAGE...ABOUT 10 DEGREES BELOW ON MONDAY AND 5 DEGREES BELOW ON
TUESDAY...AS THE AIRMASS SLOWLY MODERATES. MOS LOOKS A BIT TOO COLD
FOR MAXES BOTH DAYS...PERHAPS FROM OVERESTIMATING/ANTICIPATING SNOW
COVER FROM YESTERDAY/S SYSTEM...AND LEANED WARM VERSUS THEM.
(WEDNESDAY - SATURDAY)
A BIT OF A PATTERN SHIFT OF SOME NOTE OCCURS EARLY IN THIS PERIOD
WITH LONGWAVE TROF SHIFTING TO THE ERN CONUS...ALBEIT NOT QUITE WHAT
IT WAS WHEN IT WAS OVER THE W...AND IS ANTICIPATED TO BE GREATLY
DE-AMPLIFIED. THIS WILL GIVE US A W-NW FLOW AND IS EXPECTED TO BE
MARKED BY LITTLE OR NO WX-MAKING DISTURBANCES OF NOTE AND TEMPS AT
OR ABOVE AVERAGE.
ONCE WE GET IN THIS PATTERN...IT LOOKS LIKE IT WILL STAY FOR A WHILE
AS VERY LATE IN THIS PERIOD AMPLIFICATION OF THE RIDGE WILL TAKE
PLACE OVER THE WRN CONUS AND THIS WILL CAUSE A CORRESPONDING
DEEPENING OF THE TROF IN THE E. IF THIS HOLDS...SEVERAL WAVES OF
NOTABLE COLD COULD COME OUT OF THIS. BUT IF YOU ARE LOOKING FOR
SNOW...SYSTEMS TO TAKE ADVANTAGE OF THIS APPEAR SCARCE.
TES
&&
.AVIATION...
ISSUED AT 1027 PM CST SAT JAN 12 2013
LOOKING AT THE LATEST RADAR LOOP MUCH OF THE SIGNIFICANT
PRECIPITATION SHOULD SHIFT E OF THE TAF SITES BY 06Z SUN OR
SHORTLY THEREAFTER. LIGHT SNOW SHOULD TAPER OFF TO FLURRIES IN UIN
AND COU LATE TGT...WHILE LIGHT RAIN AND LIGHT FREEZING RAIN
CHANGES TO MAINLY FREEZING DRIZZLE IN THE ST LOUIS METRO AREA LATE
TGT AND CONTINUES INTO EARLY SUN MRNG. MAY SEE SOME IMPROVEMENT IN
THE CLOUD CEILING HEIGHT IN UIN AND COU ALREADY LATE TGT WITH
MAINLY MVFR CONDITIONS EXPECTED. IN THE ST LOUIS METRO AREA THE
CEILING HEIGHT SHOULD VARY BETWEEN MVFR AND IFR LATE TGT INTO SUN
MRNG. WILL SEE IMPROVEMENT IN THE CEILING HEIGHT ON SUN AS THE
SFC RIDGE OVER THE NRN PLAINS BUILDS SEWD INTO MO WITH VFR
CONDITIONS IN UIN AND COU IN THE AFTN AND VFR CONDITIONS IN THE
ST LOUIS METRO AREA BY LATE SUN AFTN OR EARLY EVNG. NWLY SFC WINDS
WILL CONTINUE LATE TGT AND SUN...DIMINISHING SUN NGT AS THE SFC
PRESSURE GRADIENT RELAXES.
SPECIFICS FOR KSTL...THE FREEZING RAIN WILL TAPER OFF TO FREEZING
DRIZZLE LATE TGT AS THE COLD FRONT EXTENDING FROM IN SW THROUGH
THE MO BOOTHEEL AND AR CONTINUES TO SHIFT FURTHER SEWD. THERE MAY
ALSO BE FLURRIES SUN MRNG AS THE COLD AIR DEEPENS OVER THE AREA.
THE CEILING HEIGHT SHOULD HOVER AROUND 1000 FT LATE TGT...THEN
GRADUALLY IMPROVE DURING THE DAY ON SUN...AND SCATTER OUT BY LATE
SUN AFTN OR EARLY SUN EVNG. THE NWLY SFC WIND WILL CONTINUE...
EVENTUALLY DIMINISHING SUN NGT.
GKS
&&
.PRELIMINARY POINT TEMPS/POPS...
ST LOUIS 29 16 29 18 / 20 0 0 0
QUINCY 25 10 26 13 / 10 0 0 0
COLUMBIA 26 11 29 14 / 10 0 0 0
JEFFERSON CITY 28 11 29 14 / 10 0 0 0
SALEM 33 15 30 17 / 40 5 5 0
FARMINGTON 32 14 32 15 / 20 0 5 0
&&
.LSX WATCHES/WARNINGS/ADVISORIES...
MO...NONE.
IL...NONE.
&&
$$
WFO LSX
AREA FORECAST DISCUSSION
NWS KANSAS CITY/PLEASANT HILL MO
1128 PM CST SAT JAN 12 2013
...UPDATED AVIATION DISCUSSION...
.UPDATE...
/1051 PM CST Sat Jan 12 2013/
Was initially concerned with light freezing drizzle from Clinton to
Boonville per RAP forecast soundings. However the feeling is it
should have began to materialize by now and it isn`t. Additionally
RAP soundings show a loss of saturation in the lower levels after 06z
so it would appear we missed the window. As a result have cancelled
the advisory for the entire CWA. It would appear the earlier snow
produced 2-3 inches generally south of I 70 and from Miami and Linn
Counties eastward...missing most of the KC Metro.
Bailey
&&
.UPDATE...
/714 PM CST Sat Jan 12 2013/
After intense late afternoon and early evening snow, it has really
diminished rapidly over most of the CWA. Snowfall reports have ranged
from 1-3 inches across the affected areas, with some locations...most
notably along the 50 hwy corridor reporting sporadic sleet and
freezing rain at the onset of precipitation before changing to all
snow. Rapid precip ending could be due in part to large area of dry
air to the west working in. HRRR has pegged this pretty good, and
even it has underestimated the decrease in precipitation to some
degree. As a result I have cancelled much of the western and northern
portions of the winter weather advisory, and will likely need to
cancel the rest of the advisory later this evening as the last of the
snow winds down.
Bailey
&&
.DISCUSSION...
Near Term (Through Tonight)...
Recent water vapor imagery shows a deepening positive tilt shortwave
trough ejecting across the TX/OK panhandle region, with an extensive
Pacific moist plume spreading northward from eastern Texas into the
Mid Mississippi valley region. Large scale ascent was rapidly
increasing within a broad area bound between the surface cold front
across central Arkansas and the trailing sloping frontal region that
extends back into SE Kansas through NE Missouri.
12Z upper air soundings showed a number of potential problems with
the near term forecast:
1.) Extensive dry air present both above and below the frontogenetic
region.
2.) A layer of 0 to +2C air lingering across the southern CWA
3.) Weak static stability (-EPV) present just above the mid level
frontogenesis region -- albeit in increasingly dry air.
Since 19Z, blossoming of echos on regional radar imagery confirms
large scale ascent associated with a 300mb jet streak was beginning
to overspread eastern KS/OK into MO/AR. Precipitation has been
largely showery in nature and has had difficulty reaching the ground
in the local CWA. Most of the initial virga sublimation will likely
aid in rapid top down saturation over the next 1-3 hours. Light snow
and sleet have been reported from the NWS office southward and this
is likely the beginning of tonight`s event. In the absence of
significant cold advection, diabatic cooling will likely be the
primary driving mechanism to eliminate the lingering warm nose, with
any PL over the far srn CWA going to all snow.
For this evening, 12Z models still indicate a rather strong coupling
between 850-600mb sloped frontogenesis and the upper jet streak.
Three big questions remain with this evening`s forecast. One being
the character of the snow, as stability parameters indicate we may
see elongated banding and a lack of uniformity. The second is the
primary moist axis feeding from srn Texas into AR and southern MO
which could perhaps drive more efficient precipitation south and
east of the local region. Lastly, the primary forcing occurs in
temperatures much warmer (-4 to -8C) than dendrite preference which
would reduce overall accumulations. With that said, the 1-3" painted
looks right on target with my analysis, with I-35 very near the
western bound of where frontogenetic forcing drops off rapidly.
Bottom line is that although this is a nuisance snow, amounts could
still vary quite a bit from locale to locale within that 1-3"
spectrum, and would not be surprised to see a slight buffer either
side of that range within the advisory area. Snow should taper off
quickly west to east after midnight as the subsidence overspreads
the area in the wake of the jet streak.
Bookbinder
Short Term (Sunday through Monday Night)...
Skies will clear from west to east on Sunday, with temperatures
really the only issue of concern through Monday Night. Readings will
largely be dictated by the axis of incoming high pressure and the
extent of snow cover once cold advection ceases by Monday morning.
Didn`t see any reason to stray too far from previous forecast.
Bookbinder
Medium Range (Tuesday through Saturday)...
A weakening, strongly tilted trough will gradually push east and
become enveloped by the northern jet stream toward the beginning of
the period, allowing the overall pattern to transition to a warmer,
more zonal flow across the central U.S. by the middle of next week.
Temperatures could still be a bit cool on Tuesday as the trough
departs, with most models indicating a lingering pocket of 850 mb
temperatures in the -7 to -9 degree range over northern Missouri. By
Wednesday, temperatures should rise to near or slightly above normal
values, with highs likely in the upper 30`s to mid 40`s for
Wednesday through Saturday. There remains a small possibility for
temperatures to be significantly colder on Thursday and Friday as
the trough over eastern Canada deepens, potentially allowing some
very cold air to filter into eastern portions of the CWA. This was
indicated yesterday by the EC and today by the GEM, but still
remains an outlying solution.
Precipitation is not expected through this period, with surface high
pressure generally dominating the central Plains and the jet stream
remaining well to the north.
Laflin
&&
.AVIATION...
For the 06Z TAFs...VFR conditions expected during this forecast
period. Will see mid clouds through mid Sunday morning over west
central MO until an upper level jet streak passes by. Otherwise, nw
winds around 10kts, a little higher at KSTJ, through Sunday
afternoon, then weaken as high pressure center moves in.
MJ
&&
.EAX WATCHES/WARNINGS/ADVISORIES...
MO...NONE.
KS...NONE.
&&
$$
WFO EAX
AREA FORECAST DISCUSSION
NWS KANSAS CITY/PLEASANT HILL MO
1057 PM CST Sat Jan 12 2013
.UPDATE...
/1051 PM CST Sat Jan 12 2013/
Was initially concerned with light freezing drizzle from Clinton to
Boonville per RAP forecast soundings. However the feeling is it
should have began to materialize by now and it isn`t. Additionally
RAP soundings show a loss of saturation in the lower levels after 06z
so it would appear we missed the window. As a result have cancelled
the advisory for the entire CWA. It would appear the earlier snow
produced 2-3 inches generally south of I 70 and from Miami and Linn
Counties eastward...missing most of the KC Metro.
/714 PM CST Sat Jan 12 2013/
After intense late afternoon and early evening snow, it has really
diminished rapidly over most of the CWA. Snowfall reports have ranged
from 1-3 inches across the affected areas, with some locations...most
notably along the 50 hwy corridor reporting sporadic sleet and
freezing rain at the onset of precipitation before changing to all
snow. Rapid precip ending could be due in part to large area of dry
air to the west working in. HRRR has pegged this pretty good, and
even it has underestimated the decrease in precipitation to some
degree. As a result I have cancelled much of the western and northern
portions of the winter weather advisory, and will likely need to
cancel the rest of the advisory later this evening as the last of the
snow winds down.
Bailey
&&
.DISCUSSION...
Near Term (Through Tonight)...
Recent water vapor imagery shows a deepening positive tilt shortwave
trough ejecting across the TX/OK panhandle region, with an extensive
Pacific moist plume spreading northward from eastern Texas into the
Mid Mississippi valley region. Large scale ascent was rapidly
increasing within a broad area bound between the surface cold front
across central Arkansas and the trailing sloping frontal region that
extends back into SE Kansas through NE Missouri.
12Z upper air soundings showed a number of potential problems with
the near term forecast:
1.) Extensive dry air present both above and below the frontogenetic
region.
2.) A layer of 0 to +2C air lingering across the southern CWA
3.) Weak static stability (-EPV) present just above the mid level
frontogenesis region -- albeit in increasingly dry air.
Since 19Z, blossoming of echos on regional radar imagery confirms
large scale ascent associated with a 300mb jet streak was beginning
to overspread eastern KS/OK into MO/AR. Precipitation has been
largely showery in nature and has had difficulty reaching the ground
in the local CWA. Most of the initial virga sublimation will likely
aid in rapid top down saturation over the next 1-3 hours. Light snow
and sleet have been reported from the NWS office southward and this
is likely the beginning of tonight`s event. In the absence of
significant cold advection, diabatic cooling will likely be the
primary driving mechanism to eliminate the lingering warm nose, with
any PL over the far srn CWA going to all snow.
For this evening, 12Z models still indicate a rather strong coupling
between 850-600mb sloped frontogenesis and the upper jet streak.
Three big questions remain with this evening`s forecast. One being
the character of the snow, as stability parameters indicate we may
see elongated banding and a lack of uniformity. The second is the
primary moist axis feeding from srn Texas into AR and southern MO
which could perhaps drive more efficient precipitation south and
east of the local region. Lastly, the primary forcing occurs in
temperatures much warmer (-4 to -8C) than dendrite preference which
would reduce overall accumulations. With that said, the 1-3" painted
looks right on target with my analysis, with I-35 very near the
western bound of where frontogenetic forcing drops off rapidly.
Bottom line is that although this is a nuisance snow, amounts could
still vary quite a bit from locale to locale within that 1-3"
spectrum, and would not be surprised to see a slight buffer either
side of that range within the advisory area. Snow should taper off
quickly west to east after midnight as the subsidence overspreads
the area in the wake of the jet streak.
Bookbinder
Short Term (Sunday through Monday Night)...
Skies will clear from west to east on Sunday, with temperatures
really the only issue of concern through Monday Night. Readings will
largely be dictated by the axis of incoming high pressure and the
extent of snow cover once cold advection ceases by Monday morning.
Didn`t see any reason to stray too far from previous forecast.
Bookbinder
Medium Range (Tuesday through Saturday)...
A weakening, strongly tilted trough will gradually push east and
become enveloped by the northern jet stream toward the beginning of
the period, allowing the overall pattern to transition to a warmer,
more zonal flow across the central U.S. by the middle of next week.
Temperatures could still be a bit cool on Tuesday as the trough
departs, with most models indicating a lingering pocket of 850 mb
temperatures in the -7 to -9 degree range over northern Missouri. By
Wednesday, temperatures should rise to near or slightly above normal
values, with highs likely in the upper 30`s to mid 40`s for
Wednesday through Saturday. There remains a small possibility for
temperatures to be significantly colder on Thursday and Friday as
the trough over eastern Canada deepens, potentially allowing some
very cold air to filter into eastern portions of the CWA. This was
indicated yesterday by the EC and today by the GEM, but still
remains an outlying solution.
Precipitation is not expected through this period, with surface high
pressure generally dominating the central Plains and the jet stream
remaining well to the north.
Laflin
&&
.AVIATION...
For the 18Z TAFs, recent model guidance still suggests the bulk of
this evening`s winter weather event will likely skate just east of
the terminals with MKC seeings the greatest impacts of some
accumulating snow. A significant layer of dry air both above and
below a narrow corridor of strong elevated frontogenesis is the main
prohibiting factor.
VFR conditions will continue through 00Z with gradually lowering mid
cloud. Ceilings should steadily fall thereafter.
Basically have kept STJ dry, MCI on the fringe with MVFR to perhaps
brief IFR conditions this evening, and MKC in the steadier snow this
evening with IFR conditions likely. Conditions should rapidly
improve after around 07Z.
Winds will remain northwest to north-northwest at around 10 knots.
Bookbinder
&&
.EAX WATCHES/WARNINGS/ADVISORIES...
MO...NONE.
KS...NONE.
&&
$$
WFO EAX
AREA FORECAST DISCUSSION
NWS HASTINGS NE
910 PM CST MON JAN 14 2013
.UPDATE...AS OF 03Z WATER VAPOR IMAGERY INDICATES A LONGWAVE
TROUGH ACROSS THE CENTRAL CONUS. A WEAK RIDGE OF HIGH PRESSURE IS
ALSO NOTED AT THE SURFACE OVER PORTIONS OF THE MISSOURI VALLEY.
LOW LEVEL RETURN FLOW IS BEING OBSERVED OVER PORTIONS OF WESTERN
KANSAS...AS WELL AS PORTIONS OF WESTERN AND CENTRAL NEBRASKA AND
AS A RESULT...WEAK ISENTROPIC UPGLIDE AND SATURATION ALONG THE
275-280K SURFACES PERSIST ACROSS PORTIONS OF THE REGION. THIS
ISENTROPIC UPGLIDE...WORKING IN CONCERT WITH WEAK MID LEVEL
THERMAL ADVECTION AHEAD OF THE LONGWAVE TROUGH...IS PROMOTING A
WEAK BAND OF LIGHT SNOW OVER PORTIONS OF NORTHWEST KANSAS AND
SOUTHWEST NEBRASKA...WITH FLURRY ACTIVITY NOTED ON KUEX DATA AND
OBSERVED AT KHDE WITH IN THE PAST HOUR. SHORT TERM GUIDANCE FROM
THE RAP AND NAM SUGGEST THE ISENTROPIC UPGLIDE SHOULD DIMINISH
THROUGH THE NEXT SIX HOURS OR SO BUT UNTIL THAT TIME...OCCASIONAL
FLURRY ACTIVITY CANNOT BE RULED OUT ACROSS THE WEST/NORTHWEST HALF
OF OUR CWA. WENT AHEAD AND INTRODUCED FLURRY WORDING TO THE
FORECAST FOR THESE LOCATIONS FOR TONIGHT AS A RESULT. THE
REMAINDER OF THE FORECAST REMAINS IN GREAT SHAPE...WITH ONLY SOME
MINOR TWEAKS MADE TO HOURLY TEMPERATURE...DEWPOINT...AND WIND
GRIDS TO BETTER REFLECT CURRENT OBSERVATIONS.
&&
.PREV DISCUSSION... /ISSUED 508 PM CST MON JAN 14 2013/
AVIATION...00Z KGRI TAF. VFR CONDITIONS TO CONTINUE THROUGH THE
NEXT 24 HOURS. MID LEVEL CEILINGS NEAR 7000FT AGL ARE EXPECTED
THROUGH 10Z...WITH CLEAR SKIES THEREAFTER. THE SURFACE WIND WILL
REMAIN FROM THE SOUTHWEST AT AROUND 06KTS TONIGHT...INCREASING TO
AROUND 10KTS DURING THE DAY TUESDAY. VISIBILITY RESTRICTION IS NOT
EXPECTED AT KGRI THROUGH THE NEXT 24 HOURS.
PREV DISCUSSION... /ISSUED 358 PM CST MON JAN 14 2013/
SHORT TERM...TONIGHT THROUGH TUESDAY. COLD AND DRY WEATHER WILL
CONTINUE WITH BELOW NORMAL TEMPERATURES...ALTHOUGH TUESDAY WILL BE
AT LEAST SOMEWHAT WARMER THAN TODAY.
TONIGHT...THE UPPER LEVEL TROUGH AXIS WILL SLIDE INTO OUR FORECAST
AREA AND SOME MID LEVEL CLOUDS ARE EXPECTED. THIS SHOULD KEEP LOW
TEMPERATURES A FEW DEGREES WARMER THAN LAST NIGHT. HOWEVER...THE
CLOUDS MAY BEGIN TO CLEAR ACROSS OUR NORTHWEST PRIOR TO SUNRISE
ALLOWING FOR GREATER RADIATIONAL COOLING. THEREFORE...EXPECT THE
COLDEST READINGS TO LIKELY RUN FROM AROUND ORD TO GOTHENBURG.
TOMORROW...THE LOW LEVEL WIND FIELD WILL BE WESTERLY ALLOWING WARMER
AIR TO SLOWLY WORK BACK INTO THE PLAINS. IN ADDITION...SUNNY TO
MOSTLY SUNNY SKIES ARE EXPECTED. THE STRIPE OF SNOW COVER ACROSS THE
CENTER OF OUR CWA WILL CONTINUE TO KEEP HIGH TEMPERATURES SEVERAL
DEGREES COOLER OVER SNOW COVERED AREAS THAN OVER SNOW FREE AREAS.
WILL CALL FOR ABOVE FREEZING HIGH TEMPERATURES OVER SNOW FREE
AREAS...WITH HIGHS A FEW DEGREES BELOW FREEZING OVER OUR SNOW
COVERED AREAS.
LONG TERM...(TUESDAY NIGHT THROUGH MONDAY)
THE MAIN STORY: A STRING OF VERY NICE/MILD DAYS BEGINS WED AS THE
CURRENT COLD SNAP EASES...GIVING US A BREAK BEFORE THE "POTENTIALLY"
COLDEST AIR SO FAR THIS SEASON EARLY NEXT WEEK.
PATTERN: THE LONG-WAVE FLOW YOU SEE WED /WRN N AMERICA RIDGE AND AN
ERN TROF/ WILL BE WITH US FOR THE NEXT 10 DAYS. THE GFS ENSEMBLE HAS
A STRONG SIGNAL FOR A +PNA PATTERN THRU THIS PERIOD...PEAKING ON THE
21ST. THIS MEANS THE ERN USA WILL BE DEALING WITH FRIGID ARCTIC COLD
DELIVERED BY A TRAIN OF ALBERTA CLIPPERS. FOR NOW NW FLOW WILL LOCK
THE ARCTIC FRONT JUST NE OF THE FCST AREA. AND WHILE WE WILL BENEFIT
FROM DOWNSLOPE WARMING IN THE WARM SECTOR OF THESE CLIPPERS...
BELIEVE WE WILL HAVE TO DEAL WITH SPELL OF BITTER ARCTIC COLD DURING
THE NEXT 10 DAYS. MODELS HAVE BEEN HINTING THAT THE WRN FRINGE OF
THIS AIR MASS BACKS INTO CNTRL PLAINS NEXT SUN-MON. WATCH THE SWD
PROGRESSION WITH EACH CLIPPER! THE GFS ENSEMBLE MEAN ALREADY HAS -1
STANDARD DEVIATION TEMPS AT H8 IN THAT TIMEFRAME AND THAT/S WITH
-15C. 00Z EC ENSEMBLE MEAN HAS -12C BUT THAT/S WITH A LOT GREATER
MEMBERSHIP AND MORE AVERAGING. THE 06Z/12Z DETERMINISTIC GFS CYCLES
HAVE -17 OR -18C WHICH WOULD SUPPORT HIGHS IN THE SINGLE DIGITS OVER
S-CNTRL NEB. THIS WITH HIGH PRES NEAR OR IN EXCESS OF 1040 MB.
A STEADY-STATE PATTERN OFFERS ABOVE AVERAGE FCST CONFIDENCE.
BOTTOM LINE...TEMPS WILL AVERAGE ABOVE NORMAL /OR MUCH ABOVE NORMAL
FOR AREAS WITH NO SNOW COVER/ THRU SAT THEN TURNING MUCH BELOW
NORMAL SUN-MON THRU THE MIDDLE OF NEXT WEEK. DRIER THAN NORMAL WITH
MOST PLACES PROBABLY NOT EVEN REGISTERING A TRACE OF PRECIP OVER THE
NEXT 10 DAYS.
HAZARDS: 1) A WARM FRONTAL PASSAGE COULD THREATEN A BIT OF LIGHT SN
OR FRZG DRIZZLE TUE NGT OVER OUR S-CNTRL NEB COUNTIES.
2) THERE IS A CHANCE OF DANGEROUSLY LOW WIND CHILLS EARLY
NEXT WEEK. TOO EARLY TO TELL ON WIND SPEEDS BUT
SOMETHING TO WATCH.
UPCOMING PCPN OPPORTUNITIES: NOTHING SUBSTANTIAL.
THE DAILY DETAILS...
ALL INITIALIZED LOW TEMPS WERE REPLACED WITH ITS BIAS CORRECTED
COUNTERPART UNLESS OTHERWISE NOTED.
TUE NGT: INCREASING CLOUDS. MILD WITH A BREEZY SW WIND SHIFTING TO
THE W. WARM FRONTAL PASSAGE. SOUNDINGS THREATEN A TOUCH OF LIGHT SN
OR FRZG DRIZZLE. IT/S NOT IN THE FCST BUT SOMETHING TO WATCH. TEMPS
WILL DROP INITIALLY WITH SUNSET THEN TEMPS HOLDING STEADY OR SLOWLY
RISING.
WED: BECOMING M/SUNNY. CLIPPER RACES ACROSS SRN CANADA. TEMPS ARE
BIAS CORRECTED MEX MOS. THE NAM HAS TOO MUCH CONTAMINATION FROM ITS
MODELED SNOW COVER. BUT DID I GO WARM ENOUGH IN THE NO/LOW SNOW
COVER AREAS? WE/LL BE STARTING FROM VERY MILD MID-UPPER 20S AND SOME
2M TEMP GUIDANCE IS SUGGESTING LOW 50S OUTSIDE AREAS WITH REMAINING
CRUSTY SNOW COVER.
THU: HIGH PRES DRIFTS THRU IN THE MRNG WITH SW WINDS DEVELOPING.
M/SUNNY. HAVE TEMPS FAIRLY CLOSE TO WED/S HIGHS. USED BIAS CORRECTED
MAV MOS AGAIN. WITH RETURN FLOW DELAYED INTO THE AFTN...FCST TEMPS
COULD END UP 2-3F TOO WARM.
FRI: ANOTHER VERY NICE DAY IN THE WARM SECTOR OF ANOTHER CLIPPER
ROTATING THRU THE GREAT LAKES. TEMPS ARE BIAS CORRECTED MEX MOS.
COULD SEE ORD AND STOCKTON/OSBORNE/BELOIT FLIRT WITH 50F!
SAT: PROBABLY ANOTHER PLEASANT DAY BUT WITH AN ARCTIC COLD FRONTAL
PASSAGE. UNCERTAINTY IN TEMPS AS MODELS STRUGGLE WITH EXACT TIMING/
LOCATION OF THE FRONT.
WIND: WE PROBABLY HAVE TO DEAL WITH A PERIOD OF BLUSTERY N WINDS
BEHIND THE FRONT. NOT SURE ON THE TIMING.
SUN-MON: AFTER COORDINATING WITH SURROUNDING OFFICES...ALL DAYTIME/
NIGHTTIME TEMPS WERE LOWERED TO THE WEIGHTED CONSENSUS OF THE 3
BEST-VERIFYING TEMP GUIDES.
SUN: COLDER BUT NOT UNBEARABLE.
SUN NGT OR MON: THE ARCTIC FLOOD-GATES OPEN WITH A BITTER 1050 MB
HIGH SLIDING DOWN THE FRONT RANGE.
MON: BITTERLY COLD AND WE NEED TO KEEP THE DOOR OPEN FOR SINGLE
DIGITS HIGH TEMPS! ESPECIALLY OVER OUR NEB COUNTIES. EVEN WITH THE
MORE CONSERVATIVE GFS AND 00Z EC...IF WE END UP CLOUDY IT WILL BE A
SLAM-DUNK. WATCH FOR LOW CLOUDS TO GET TRAPPED UNDER THE FRONTAL
INVERSION. THE 12Z EC CAME IN AND IS PROBABLY THE WORST CASE
SCENARIO...WITH -24C DOWN TO GRI AT 00Z/TUE.
EVEN THO WE/VE LOWERED TEMPS...WE STILL COULD BUST ANOTHER 5-10F TOO
HIGH.
&&
.GID WATCHES/WARNINGS/ADVISORIES...
NE...NONE.
KS...NONE.
&&
$$
910PM UPDATE/AVIATION...BRYANT
SHORT TERM...WESELY
LONG TERM...HALBLAUB
AREA FORECAST DISCUSSION
NWS NORTH PLATTE NE
745 PM CST MON JAN 14 2013
.UPDATE...
.DISCUSSION...
WE ARE FAST APPROACHING FCST LOWS ACROSS THE NORTH WHERE SKIES ARE
CLEAR. SO A NEW MIN TEMPERATURE FCST IS OUT. THE REST OF THE FCST
IS ON TRACK.
&&
.PREV DISCUSSION... /ISSUED 531 PM CST MON JAN 14 2013/
UPDATE...
AVIATION...
VFR IS EXPECTED ALL AREAS TONIGHT AND TUESDAY.
A WEAK UPPER LEVEL DISTURBANCE ACROSS SWRN NEB WILL SPREAD LIGHT
SNOW THROUGH THE EVENING HOURS. IT IS NOT CLEAR MVFR WILL COVER
THIS AREA. LOCAL MVFR COULD DEVELOP AS THIS AREA OF SNOW MOVES
THROUGH. ANOTHER AREA TO WATCH WOULD BE NORTHWEST NEBRASKA LATE
TOMORROW AFTERNOON. AN UPPER LEVEL DISTURBANCE ACROSS THE NRN HIGH
PLAINS WILL BE MOVING SOUTHEAST TOWARD NORTHWEST NEBRASKA LATE IN
THE AFTERNOON. THIS DISTURBANCE HAS THE POTENTIAL TO PRODUCE MVFR
CIGS. OTHERWISE VFR WILL PREVAIL.
PREV DISCUSSION... /ISSUED 426 PM CST MON JAN 14 2013/
UPDATE...
DISCUSSION...
QUICK UPDATE FOR SOUTHWEST NEBRASKA. THE RUC13 SHOWS AND AREA OF
LIGHT SNOW ON THE 285K INSENTROPIC SFC MOVING EAST THIS EVENING.
THE NEW FORECAST SLOWS THIS DOWN ABOUT 3 HOURS AND RAISES THE POP
TO 50 PERCENT. LESS THAN AN INCH ACCUMULATION IS EXPECTED
ALTHOUGH THE RUC SHOWS 3 INCHES. THE RUC IS OFTEN TOO WET. REST OF
THE FORECAST IS GOOD.
PREV DISCUSSION... /ISSUED 245 PM CST MON JAN 14 2013/
SYNOPSIS...
IN THE UPPER LEVELS...THE LARGE SCALE CYCLONIC FLOW CONTINUES
OVER A LARGE PART OF THE CENTRAL AND WESTERN U.S. RUNNING A 24 HOUR
LOOP OF THE IMAGERY...ONE CAN SEE THE DIGGING AND NARROWING OF THE
TROUGH. ANALYSIS OF THE 20Z SURFACE DATA REVEALED A WARM FRONT
DEVELOPING ACROSS EASTERN MONTANA AND EASTERN WYOMING.
SHORT TERM...TONIGHT THROUGH TUESDAY NIGHT.
A LOOK AT THE 280-290K LAYER INDICATES SOME WEAK ISENTROPIC LIFT
CONTINUING INTO THIS EVENING IN EXTREME SOUTHWEST NEBRASKA.
HOWEVER...VERY LITTLE MOISTURE AND ACCUMULATIONS WILL BE HALF AN
INCH OR LESS.
FOR TUESDAY...A WARM FRONT IS EXPECTED INTO WESTERN NEBRASKA BY
EARLY EVENING. AGAIN...IN THE 280-290K LAYER...ISENTROPIC UPGLIDE IS
LIKELY TO PRODUCE SOME CLOUDINESS AND POSSIBLY SOME LIGHT SNOW IN
THE EVENING AND LIGHT FREEZING DRIZZLE LATE TUESDAY NIGHT AND VERY
EARLY WEDNESDAY.
MEDIUM RANGE/EXTENDED...WEDNESDAY THROUGH SUNDAY.
DRY AND MUCH WARMER WEATHER CAN BE EXPECTED WEDNESDAY THROUGH
FRIDAY IN THE AFTERMATH OF THE WARM FRONT.
MUCH COLDER WEATHER IS EXPECTED AGAIN AS A BACK-DOOR FRONT COMES
ACROSS SATURDAY NIGHT AND SUNDAY. THE FRONT STALLS ALONG THE EASTERN
SLOPE OF THE ROCKIES AND SOUTHWEST FLOW WILL PRODUCE ISENTROPIC LIFT
AND COULD GIVE SOME POTENTIAL FOR WIDESPREAD SNOW MONDAY AS THE
SYSTEM MAKES ITS WAY BACK TO THE EAST-NORTHEAST. AT THAT RANGE...
THE UNCERTAINTY IS VERY HIGH REGARDING AMOUNTS AND INTENSITY OF
PRECIPITATION.
AVIATION...
FOR THE 18Z TAF FORECAST CYCLE...GENERAL VFR EXPECTED TODAY
ACROSS MOST AREA TERMINALS. THE EXCEPTION BEING ACROSS FAR
SOUTHWEST NEBRASKA TODAY...POSSIBLY AFFECTING THE KOGA AND KIML
TERMINALS WHERE SCATTERED LIGHT SNOW MAY BRIEFLY REDUCE VISIBILITIES
INTO MVFR. MODEL GUIDANCE HAS THE REMAINING LIGHT SNOW DISSIPATING
LATER THIS AFTERNOON...IF NOT ALREADY SO...THEREAFTER DRIER AIR
ALOFT WILL WORK BACK ACROSS THE REGION...WITH NO VISIBILITY OR
CEILING RESTRICTIONS ANTICIPATED. FOR THE OVERNIGHT...NAM SHORT
TERM GUIDANCE HINTS AT REDUCED VISIBILITY /DOWN TO 3SM/ AT KLBF
AFTER 06Z WITH THE FORMATION OF LOW FOG. FEEL THAT THE SOLUTION IS
OVERLY AMBITIOUS WITH THE REMAINING LOW LEVEL MOISTURE...SO WILL NOT
INCLUDE A MENTION OF MVFR VISIBILITY IN THE OFFICIAL TAF FORECAST
NOW. OTHERWISE BROAD SURFACE HIGH PRESSURE WILL KEEP WIND SPEEDS
RELATIVELY LIGHT AND VARIABLE FOR ALL TERMINALS.
&&
.LBF WATCHES/WARNINGS/ADVISORIES...NONE.
&&
$$
SHORT TERM/EXTENDED...BROOKS
AVIATION...CDC
AREA FORECAST DISCUSSION...UPDATED
NWS NORTH PLATTE NE
531 PM CST MON JAN 14 2013
.UPDATE...
.AVIATION...
VFR IS EXPECTED ALL AREAS TONIGHT AND TUESDAY.
A WEAK UPPER LEVEL DISTURBANCE ACROSS SWRN NEB WILL SPREAD LIGHT
SNOW THROUGH THE EVENING HOURS. IT IS NOT CLEAR MVFR WILL COVER
THIS AREA. LOCAL MVFR COULD DEVELOP AS THIS AREA OF SNOW MOVES
THROUGH. ANOTHER AREA TO WATCH WOULD BE NORTHWEST NEBRASKA LATE
TOMORROW AFTERNOON. AN UPPER LEVEL DISTURBANCE ACROSS THE NRN HIGH
PLAINS WILL BE MOVING SOUTHEAST TOWARD NORTHWEST NEBRASKA LATE IN
THE AFTERNOON. THIS DISTURBANCE HAS THE POTENTIAL TO PRODUCE MVFR
CIGS. OTHERWISE VFR WILL PREVAIL.
&&
.PREV DISCUSSION... /ISSUED 426 PM CST MON JAN 14 2013/
UPDATE...
DISCUSSION...
QUICK UPDATE FOR SOUTHWEST NEBRASKA. THE RUC13 SHOWS AND AREA OF
LIGHT SNOW ON THE 285K INSENTROPIC SFC MOVING EAST THIS EVENING.
THE NEW FORECAST SLOWS THIS DOWN ABOUT 3 HOURS AND RAISES THE POP
TO 50 PERCENT. LESS THAN AN INCH ACCUMULATION IS EXPECTED
ALTHOUGH THE RUC SHOWS 3 INCHES. THE RUC IS OFTEN TOO WET. REST OF
THE FORECAST IS GOOD.
PREV DISCUSSION... /ISSUED 245 PM CST MON JAN 14 2013/
SYNOPSIS...
IN THE UPPER LEVELS...THE LARGE SCALE CYCLONIC FLOW CONTINUES
OVER A LARGE PART OF THE CENTRAL AND WESTERN U.S. RUNNING A 24 HOUR
LOOP OF THE IMAGERY...ONE CAN SEE THE DIGGING AND NARROWING OF THE
TROUGH. ANALYSIS OF THE 20Z SURFACE DATA REVEALED A WARM FRONT
DEVELOPING ACROSS EASTERN MONTANA AND EASTERN WYOMING.
SHORT TERM...TONIGHT THROUGH TUESDAY NIGHT.
A LOOK AT THE 280-290K LAYER INDICATES SOME WEAK ISENTROPIC LIFT
CONTINUING INTO THIS EVENING IN EXTREME SOUTHWEST NEBRASKA.
HOWEVER...VERY LITTLE MOISTURE AND ACCUMULATIONS WILL BE HALF AN
INCH OR LESS.
FOR TUESDAY...A WARM FRONT IS EXPECTED INTO WESTERN NEBRASKA BY
EARLY EVENING. AGAIN...IN THE 280-290K LAYER...ISENTROPIC UPGLIDE IS
LIKELY TO PRODUCE SOME CLOUDINESS AND POSSIBLY SOME LIGHT SNOW IN
THE EVENING AND LIGHT FREEZING DRIZZLE LATE TUESDAY NIGHT AND VERY
EARLY WEDNESDAY.
MEDIUM RANGE/EXTENDED...WEDNESDAY THROUGH SUNDAY.
DRY AND MUCH WARMER WEATHER CAN BE EXPECTED WEDNESDAY THROUGH
FRIDAY IN THE AFTERMATH OF THE WARM FRONT.
MUCH COLDER WEATHER IS EXPECTED AGAIN AS A BACK-DOOR FRONT COMES
ACROSS SATURDAY NIGHT AND SUNDAY. THE FRONT STALLS ALONG THE EASTERN
SLOPE OF THE ROCKIES AND SOUTHWEST FLOW WILL PRODUCE ISENTROPIC LIFT
AND COULD GIVE SOME POTENTIAL FOR WIDESPREAD SNOW MONDAY AS THE
SYSTEM MAKES ITS WAY BACK TO THE EAST-NORTHEAST. AT THAT RANGE...
THE UNCERTAINTY IS VERY HIGH REGARDING AMOUNTS AND INTENSITY OF
PRECIPITATION.
AVIATION...
FOR THE 18Z TAF FORECAST CYCLE...GENERAL VFR EXPECTED TODAY
ACROSS MOST AREA TERMINALS. THE EXCEPTION BEING ACROSS FAR
SOUTHWEST NEBRASKA TODAY...POSSIBLY AFFECTING THE KOGA AND KIML
TERMINALS WHERE SCATTERED LIGHT SNOW MAY BRIEFLY REDUCE VISIBILITIES
INTO MVFR. MODEL GUIDANCE HAS THE REMAINING LIGHT SNOW DISSIPATING
LATER THIS AFTERNOON...IF NOT ALREADY SO...THEREAFTER DRIER AIR
ALOFT WILL WORK BACK ACROSS THE REGION...WITH NO VISIBILITY OR
CEILING RESTRICTIONS ANTICIPATED. FOR THE OVERNIGHT...NAM SHORT
TERM GUIDANCE HINTS AT REDUCED VISIBILITY /DOWN TO 3SM/ AT KLBF
AFTER 06Z WITH THE FORMATION OF LOW FOG. FEEL THAT THE SOLUTION IS
OVERLY AMBITIOUS WITH THE REMAINING LOW LEVEL MOISTURE...SO WILL NOT
INCLUDE A MENTION OF MVFR VISIBILITY IN THE OFFICIAL TAF FORECAST
NOW. OTHERWISE BROAD SURFACE HIGH PRESSURE WILL KEEP WIND SPEEDS
RELATIVELY LIGHT AND VARIABLE FOR ALL TERMINALS.
&&
.LBF WATCHES/WARNINGS/ADVISORIES...NONE.
&&
$$
SHORT TERM/EXTENDED...CDC
AVIATION...CDC
AREA FORECAST DISCUSSION
NWS BISMARCK ND
1135 PM CST SAT JAN 12 2013
.DISCUSSION...LATEST FOG STRATUS IMAGERY LOOP SHOWS AN AREA OF
925MB-850MB MOISTURE/CLOUDS/ISOLATED FLURRIES IN FAR SOUTH CENTRAL
SASKATCHEWAN AND MANITOBA. THE RUC13 HAS THIS HANDLED THE BEST AND
WILL FOLLOW. LINEAR EXTRAPOLATION/TIMING BRINGS THE CLOUDS/ISOLATED
FLURRIES INTO CROSBY BY 09Z SUNDAY AND CONTINUES TO PUSH SOUTHEAST
INTO SOUTH CENTRAL NORTH DAKOTA BY MID MORNING SUNDAY. THUS HAVE
BUMPED THE SKY GRIDS UP TO REFLECT THE BKN/OVC CONDITIONS ALONG
WITH ISOLATED FLURRIES SPREADING FROM NORTHWEST TO SOUTHEAST
OVERNIGHT INTO SUNDAY MORNING. THIS WILL LIKELY HAVE AN IMPACT ON
THE CURRENT WIND CHILL ADVISORY ACROSS THE NORTH LATER TONIGHT AS
CURRENT WIND CHILL TEMPERATURES ASSOCIATED WITH THE CLOUD DECK IN
SASKATCHEWAN ARE GENERALLY RANGING BETWEEN 10 AND 15 BELOW ZERO.
ELSEWHERE THE WIND CHILL ADVISORY SHOULD HOLD UNTIL ABOUT 15Z SUNDAY
BEFORE THE CLOUDS GET INTO SOUTH CENTRAL NORTH DAKOTA. WILL CONTINUE
TO MONITOR THIS OVERNIGHT.
OTHERWISE...WATER VAPOR SHOWING A SHORTWAVE TROUGH DROPPING SOUTHEAST
FROM NORTHERN ALBERTA. NO SURFACE REFLECTION WITH THIS SHORTWAVE
AS IT IS FORECAST TO MOVE NEAR GLASGOW BY 00Z MONDAY. OVERALL FORECAST
IS ON TRACK AND MINIMAL CHANGES TO REST OF SENSIBLE WEATHER ELEMENTS.
&&
.AVIATION...VFR CONDITIONS WILL PREVAIL ACROSS WESTERN AND CENTRAL
NORTH DAKOTA THROUGH SUNDAY MORNING. A BAND OF VFR CIGS WILL MOVE
NORTHWEST TO SOUTHEAST ACROSS WESTERN AND CENTRAL NORTH DAKOTA
SUNDAY MORNING. MVFR CIGS MAY THEN DEVELOP NORTH (KISN/KMOT) SUNDAY
AFTERNOON AND ALONG THE I-94 CORRIDOR AFTER SUNSET SUNDAY.
&&
.BIS WATCHES/WARNINGS/ADVISORIES...
WIND CHILL ADVISORY UNTIL NOON CST SUNDAY FOR NDZ001>005-009>013-
017>023-025-035>037.
&&
$$
DISCUSSION...KS
AVIATION...TM
AREA FORECAST DISCUSSION
NWS CLEVELAND OH
953 PM EST MON JAN 14 2013
.SYNOPSIS...
HIGH PRESSURE WILL BUILD EAST ACROSS THE OHIO VALLEY AND LOWER
GREAT LAKES REGION TONIGHT INTO TUESDAY. TUESDAY NIGHT LOW
PRESSURE WILL ACROSS ACROSS THE NORTHERN GREAT LAKES REGION AND
DRAG A COLD FRONT ACROSS THE REGION LATE WEDNESDAY. A STRONGER
COLD FRONT WILL PASS THROUGH ON THURSDAY.
&&
.NEAR TERM /UNTIL 6 AM TUESDAY MORNING/...
A RIDGE IS BUILDING ACROSS THE AREA OVERNIGHT. THE QUESTION IS
WHAT WILL HAPPEN WITH THE CLOUDS. THE RUC/RAP MODEL KEEPS THE LOW
CLOUDS ACROSS THE ENTIRE FORECAST AREA ALL NIGHT. THE NAM MODEL
HAS THE LOW CLOUDS GONE BY MIDNIGHT...WHILE THE GFS MODEL SLOWLY
DECREASES THE CLOUDS OVERNIGHT. WENT CLOSER TO THE RAP MODEL AND
DECREASED THE CLOUDS OVER NORTHWEST OHIO AS PER THE SATELLITE
PHOTOS WHICH ARE SHOWING THE CLOUDS DECREASING BUT SOME CLOUDS ARE
REGENERATING. THE LOWS ARE TOUGH BECAUSE OF THE SKY COVER DILEMMA.
&&
.SHORT TERM /6 AM TUESDAY MORNING THROUGH THURSDAY NIGHT/...
HIGH PRESSURE CONTINUES TO BUILD ACROSS THE LOWER OHIO VALLEY
TUESDAY WITH MODELS SHOWING A SLIGHT INCREASE IN MOISTURE...MAINLY
HIGH LEVEL...ACROSS THE AREA TUESDAY EVENING. WILL CONTINUE WITH A
FAIR FORECAST THROUGH TUESDAY NIGHT. WEDNESDAY A COLD FRONT WILL
DROP ACROSS THE AREA AS THE PARENT LOW MOVES EAST ACROSS THE
CENTRAL AND NORTHERN GREAT LAKES INTO ONTARIO. MODELS BRING A
RATHER THIN SWATH OF LIMITED MOISTURE ACROSS THE AREA IN THE
AFTERNOON AS 850MB TEMPS DROP TO ABOUT -8 TO -9C EXTREME NORTHEAST
OHIO AND NWRN PA. GIVEN A 39 DEGREE LAKE -8C IS CERTAINLY NOT
EXTREME BUT COULD SEE A FEW SNOW SHOWERS DEVELOP DURING THE DAY
AND INTO THE NIGHT SO WILL HAVE SLIGHT CHANCE IN THE GRIDS FOR
WEDNESDAY...INCREASING TO CHANCE POPS WEDNESDAY NIGHT AS GFS TAKES
850MB TEMPS TO -13C TO -14C. THURSDAY THE GFS BEGINS WITH -14C
WITH THE NEXT COLD FRONT UPSTREAM ACROSS THE CENTRAL LAKES. WILL
INCREASE POPS TO LIKELY THURSDAY MORNING AS THE FRONT MOVES IN BUT
THEN BACK OFF TO CHANCE IN THE AFTERNOON AS HIGH PRESSURE BUILDS
ACROSS THE LOWER OHIO VALLEY AND DRIER AIR MOVES IN.
&&
.LONG TERM /FRIDAY THROUGH MONDAY/...
A BROAD TROUGH OVER NORTH AMERICA WILL DEEPEN OVER THE EASTERN
UNITED STATES DURING THE EXTENDED...ALLOWING AN ARCTIC AIRMASS TO
SETTLE SOUTH OVER THE REGION EARLY NEXT WEEK. LOW LEVEL BAROCLINIC ZONE
IN PLACE ACROSS THE GREAT LAKES REGION WILL LIFT NORTH ON FRIDAY AS
LOW PRESSURE APPROACHES FROM THE WEST. TEMPERATURES WILL BE AT OR
ABOVE NORMAL ON FRIDAY/SATURDAY BEFORE A SECONDARY CLIPPER SLIDES
THROUGH ON SATURDAY NIGHT AND PULLS A COLD FRONT SOUTH ACROSS THE
REGION. SCATTERED SNOW SHOWERS ARE EXPECTED ALONG THE FRONT...WITH
LAKE EFFECT INCREASING INTO SUNDAY AS THE 850MB TEMPERATURES FALL TO
-15 TO -18C AND INSTABILITY INCREASES OVER THE LAKE. A SECONDARY
WAVE WILL DIG THROUGH THE UPPER TROUGH ON MONDAY...FORCING AN EVEN
COLDER AIRMASS WITH 850MB TEMPS BELOW -20C OVER THE REGION FOR THE
EARLY PART OF NEXT WEEK.
&&
.AVIATION /03Z TUESDAY THROUGH SATURDAY/...
WIDESPREAD MVFR LINGERS ACROSS SITES THIS EVENING WITH HIGH
PRESSURE TO THE WEST CONTINUING TO BUILD OVER THE AREA. MOST
GUIDANCE NOT HANDLING CURRENT MVFR ALL THAT WELL WITH LAMP AT
LEAST INITIALIZING WITH IT. OVERALL THINKING THE TREND WILL BE FOR
MVFR TO IMPROVE DURING THE FIRST HALF OF TONIGHT...BUT WASN/T TOO
QUICK WITH IT. EXPECTING VFR ACROSS SITES THOUGH BY 12Z TUE. VFR
THROUGH THE REMAINDER OF THE TAF PERIOD WITH HIGH PRESSURE IN
CONTROL. LIGHT NW WINDS TURNING N THEN NE THROUGH TUESDAY LESS
THAN 10KT.
OUTLOOK...NON-VFR POSSIBLE WEDNESDAY NIGHT AND THURSDAY IN NE
OHIO/NW PA.
&&
.MARINE...
PRESSURE GRADIENT SHOULD CONTINUE TO WEAKEN THROUGH THE EVENING
ALLOWING WINDS TO CONTINUE TO DIMINISH. WEAK HIGH PRESSURE RIDGE
OVER THE LAKE TUE SHOULD PROVIDE LIGHT AND VARIABLE WINDS THAT WILL
BECOME SW BY WED MORNING AHEAD OF A COLD FRONT THAT WILL CROSS
THE LAKE LATE WED NIGHT. WIND SPEEDS COULD BE CLOSE TO GALE FORCE
FOR A WHILE AROUND WED EVENING.
WINDS SHOULD TURN MORE NW THU AND CONTINUE TO DIMINISH THRU THU
NIGHT AS ANOTHER RIDGE OF HIGH PRESSURE SPREADS EAST OVER OHIO. THE
RIDGE SHOULD DROP SE FRI TO ALLOW THE FLOW TO TURN SW AGAIN AND
BEGIN TO INCREASE BY FRI NIGHT.
&&
.CLE WATCHES/WARNINGS/ADVISORIES...
OH...NONE.
PA...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS...TK
NEAR TERM...KIELTYKA
SHORT TERM...TK
LONG TERM...KEC
AVIATION...ABE
MARINE...ADAMS
AREA FORECAST DISCUSSION
NWS NORMAN OK
1036 PM CST SAT JAN 12 2013
.DISCUSSION...
06Z AVIATION DISCUSSION FOLLOWS....
&&
.AVIATION...
A HARD-TO-SEE WAVE IN STRONG SW FLOW ALOFT APPEARS TO BE THE
CAUSE OF THE REMAINING SIGNIFICANT RADAR ECHOES AT THIS TIME. MOST
OF THE ECHOES PORTRAY VIRGA...BUT THERE IS REASON TO BELIEVE THAT
SOME OF THE PRECIPITATION NEAR KSPS IS REACHING THE
GROUND...PROBABLY AS -SN. THERE IS A SLIGHT CHANCE THAT THIS SNOW
MAY REACH OTHER TAF SITES TO THE N AND NE...BUT THE CHANCES ARE
CURRENTLY TOO LOW TO MENTION IN THE TAFS. BY ISSUANCE TIME...WE
HOPE TO HAVE A CLEARER RADAR TREND AND MAY MODIFY THE CURRENT
EXPECTATIONS. OTHERWISE...GENERALLY VFR CONDITIONS AND VERY
GRADUALLY DIMINISHING N WINDS ARE EXPECTED THROUGH THE PERIOD.
&&
.PREV DISCUSSION... /ISSUED 1007 PM CST SAT JAN 12 2013/
UPDATE...
CANCELLED REMAINING WINTER WEATHER ADVISORY...
DISCUSSION...
DECIDED TO CANCEL THE REMAINING WINTER WEATHER ADVISORY FOR THE
COUNTIES IN NORTHWESTERN AND CENTRAL OKLAHOMA. SURFACE ANALYSIS
CONTINUES TO SHOW VERY COLD DRY AIR AT THE SURFACE FUNNELING
ACROSS THE REGION BEHIND THE LINE OF WINTRY PRECIPITATION...WHICH
CONTINUES TO MOVE ACROSS EASTERN OKLAHOMA. 00Z SOUNDING FROM OUN
REVEALED A MOIST LAYER BETWEEN APPROXIMATELY 700MB AND 900MB.
HOWEVER...ISENTROPIC ANALYSIS AT 295K ON THE LATEST RAP AND NAM
CONTINUE TO SHOW VERY LITTLE LIFT AVAILABLE WITHIN THIS MOIST
LAYER.
SOME RESIDUAL LIGHT SNOW/FLURRIES AND POSSIBLY FREEZING DRIZZLE
MAY EXIST THROUGH MIDNIGHT ACROSS THE REGION...HOWEVER MOST
LOCATIONS WILL LIKELY STAY DRY.
ELSEWHERE ACROSS THE FORECAST AREA...A NARROW BAND OF LIGHT
SNOW/FREEZING RAIN HAS DEVELOPED JUST EAST OF WICHITA FALLS TEXAS
THROUGH 03Z. A SLIGHT SHEAR AXIS ACROSS THE AREA HAS PROVIDED JUST
ENOUGH ISENTROPIC LIFT WITHIN THE LOW LEVELS TO DEVELOP SOME
PRECIP. A THE MOMENT...DO NOT EXPECT THIS LINE TO PROGRESS VERY
FAR NORTH...AS VERY DRY AIR CONTINUES TO ADVANCE SOUTHWARD AT THE
SURFACE. HOWEVER...SOME ROADWAYS ACROSS WESTERN NORTH TEXAS MAY SE
SOME SLICK SPOTS.
HAZARDOUS TRAVEL CONDITIONS WILL PERSIST OVERNIGHT AT LOCATIONS
IMPACTED BY WINTER PRECIP THIS EVENING AS TEMPERATURES DROP WELL
BELOW FREEZING INTO THE TEENS AND 20S. IF YOU MUST TRAVEL...PLEASE
USE EXTREME CAUTION...CHECK WITH THE DEPARTMENT OF TRANSPORTATION
IN BOTH OKLAHOMA AND TEXAS FOR CONDITIONS...AND REMEMBER TO SLOW
DOWN...GIVE PLENTY OF ROOM...AND TAKE YOUR TIME.
JTK
PREV DISCUSSION... /ISSUED 533 PM CST SAT JAN 12 2013/
DISCUSSION...
00Z AVIATION DISCUSSION FOLLOWS....
AVIATION...
RADAR SHOWS A BAND OF +SN IN FAR NW OK...WHICH IS AFFECTING KGAG
AND KWWR. THIS SNOW SHOULD DIMINISH WITHIN A FEW HOURS...WHILE LOW
CLOUDS REMAIN AND ADVANCE S TOWARD KCSM LATER TONIGHT. IN
ADDITION...RA...FZRA...AND PL EXTENDS FROM KADM TO KTUL. WHILE
THIS BAND IS NOT EXPECTED TO AFFECT OUR TAF SITES...MODELS SEEM
FAIRLY CONFIDENT THAT ANOTHER BAND OF FZRA WILL FORM FARTHER WEST
BETWEEN 00Z AND 04Z OR SO. GIVEN MODEL PERFORMANCE LATELY...THIS
IS FAR FROM DEFINITE...BUT IS LIKELY ENOUGH TO INCLUDE IN TAFS. AS
THE SURFACE FRONT MOVES FARTHER AWAY...AND HIGH PRESSURE BEGINS TO
TAKE FIRMER CONTROL OF THE REGION...GRADUAL IMPROVEMENT IS
EXPECTED TOMORROW. THE TIMES IN THE TAFS...ESPECIALLY REGARDING
IMPROVEMENT TOMORROW...SHOULD BE TAKEN AS ROUGH ESTIMATES.
PREV DISCUSSION... /ISSUED 307 PM CST SAT JAN 12 2013/
DISCUSSION...
PRECIPITATION IS INCREASING IN A FEW AREAS... SHOWERS AND STORMS
EAST... A WINTRY MIX SOUTH CENTRAL.. CENTRAL AND NORTH CENTRAL
OKLAHOMA... AND VIRGA/SNOW WEST. LOW LEVEL TEMPERATURES WILL COOL
AS PRECIPITATION MOISTENS LOWER LAYERS AND TEMPERATURES APPROACH
WET BULB. THIS WILL BRING THE TEMPERATURE DOWN TO NEAR OR BELOW
FREEZING IN MANY AREAS. MEANWHILE... MID LEVELS ARE DRYING AS
SHORTWAVE MOVES THROUGH THE AREA AS SEEN ON WATER VAPOR LOOP. IN
TIME... THIS WILL REMOVE HIGH RH FROM THE DENDRITIC GROWTH ZONE
TEMPERATURE RANGE USHERING IN A TREND MORE TOWARD FREEZING RAIN
AND FREEZING DRIZZLE. SO ALTHOUGH PRECIPITATION AMOUNTS WILL
GENERALLY BE LIGHT... THE FORECAST OF FREEZING RAIN/FREEZING
DRIZZLE MAY STILL CAUSE ISSUES INTO THE EVENING HOURS ACROSS
CENTRAL AND NORTH CENTRAL OKLAHOMA... SO WILL LEAVE THE WINTER
WEATHER ADVISORY UP. DID NOT GET TOO TRICKY WITH THE PRECIPITATION
TYPES IN THE PACKAGE... KEEPING IT SNOW NORTHWEST... RAIN
SOUTHEAST WHERE TEMPERATURES WILL REMAIN ABOVE FREEZING FOR A
WHILE... AND FREEZING RAIN/SNOW/SLEET IN BETWEEN THESE AREAS.
NAM ALSO SHOWS LOW-LEVEL LIFT REDEVELOPING IN THE 06Z-14Z TIME
FRAME... ESPECIALLY IN THE SOUTHWEST. IF THIS VERIFIES... FREEZING
DRIZZLE WILL BE A POSSIBILITY AFTER MIDNIGHT THROUGH A LITTLE
AFTER SUNRISE. WILL KEEP A SLIGHT CHANCE OF FREEZING DRIZZLE AFTER
MIDNIGHT AND WILL HAVE THE NEXT SHIFTS CONTINUE TO MONITOR THE
TRENDS.
WITH WINTER WEATHER IN THE FIRST PERIOD BEING THE MAJOR WEATHER
IMPACT FOR THIS FORECAST CYCLE... ONLY MADE MINOR ADJUSTMENTS TO
THE FORECAST IN THE LATER PERIODS.
&&
.PRELIMINARY POINT TEMPS/POPS...
OKLAHOMA CITY OK 21 32 17 37 / 50 10 10 10
HOBART OK 18 35 13 36 / 10 0 0 0
WICHITA FALLS TX 24 40 18 40 / 20 10 10 10
GAGE OK 11 30 7 32 / 40 0 0 0
PONCA CITY OK 16 30 10 35 / 70 10 10 10
DURANT OK 28 40 21 43 / 30 10 10 10
&&
.OUN WATCHES/WARNINGS/ADVISORIES...
OK...NONE.
TX...NONE.
&&
$$
04/23/23
AREA FORECAST DISCUSSION
NWS NORMAN OK
1007 PM CST SAT JAN 12 2013
.UPDATE...
CANCELLED REMAINING WINTER WEATHER ADVISORY...
&&
.DISCUSSION...
DECIDED TO CANCEL THE REMAINING WINTER WEATHER ADVISORY FOR THE
COUNTIES IN NORTHWESTERN AND CENTRAL OKLAHOMA. SURFACE ANALYSIS
CONTINUES TO SHOW VERY COLD DRY AIR AT THE SURFACE FUNNELING
ACROSS THE REGION BEHIND THE LINE OF WINTRY PRECIPITATION...WHICH
CONTINUES TO MOVE ACROSS EASTERN OKLAHOMA. 00Z SOUNDING FROM OUN
REVEALED A MOIST LAYER BETWEEN APPROXIMATELY 700MB AND 900MB.
HOWEVER...ISENTROPIC ANALYSIS AT 295K ON THE LATEST RAP AND NAM
CONTINUE TO SHOW VERY LITTLE LIFT AVAILABLE WITHIN THIS MOIST
LAYER.
SOME RESIDUAL LIGHT SNOW/FLURRIES AND POSSIBLY FREEZING DRIZZLE
MAY EXIST THROUGH MIDNIGHT ACROSS THE REGION...HOWEVER MOST
LOCATIONS WILL LIKELY STAY DRY.
ELSEWHERE ACROSS THE FORECAST AREA...A NARROW BAND OF LIGHT
SNOW/FREEZING RAIN HAS DEVELOPED JUST EAST OF WICHITA FALLS TEXAS
THROUGH 03Z. A SLIGHT SHEAR AXIS ACROSS THE AREA HAS PROVIDED JUST
ENOUGH ISENTROPIC LIFT WITHIN THE LOW LEVELS TO DEVELOP SOME
PRECIP. A THE MOMENT...DO NOT EXPECT THIS LINE TO PROGRESS VERY
FAR NORTH...AS VERY DRY AIR CONTINUES TO ADVANCE SOUTHWARD AT THE
SURFACE. HOWEVER...SOME ROADWAYS ACROSS WESTERN NORTH TEXAS MAY SE
SOME SLICK SPOTS.
HAZARDOUS TRAVEL CONDITIONS WILL PERSIST OVERNIGHT AT LOCATIONS
IMPACTED BY WINTER PRECIP THIS EVENING AS TEMPERATURES DROP WELL
BELOW FREEZING INTO THE TEENS AND 20S. IF YOU MUST TRAVEL...PLEASE
USE EXTREME CAUTION...CHECK WITH THE DEPARTMENT OF TRANSPORTATION
IN BOTH OKLAHOMA AND TEXAS FOR CONDITIONS...AND REMEMBER TO SLOW
DOWN...GIVE PLENTY OF ROOM...AND TAKE YOUR TIME.
JTK
&&
.PREV DISCUSSION... /ISSUED 533 PM CST SAT JAN 12 2013/
DISCUSSION...
00Z AVIATION DISCUSSION FOLLOWS....
AVIATION...
RADAR SHOWS A BAND OF +SN IN FAR NW OK...WHICH IS AFFECTING KGAG
AND KWWR. THIS SNOW SHOULD DIMINISH WITHIN A FEW HOURS...WHILE LOW
CLOUDS REMAIN AND ADVANCE S TOWARD KCSM LATER TONIGHT. IN
ADDITION...RA...FZRA...AND PL EXTENDS FROM KADM TO KTUL. WHILE
THIS BAND IS NOT EXPECTED TO AFFECT OUR TAF SITES...MODELS SEEM
FAIRLY CONFIDENT THAT ANOTHER BAND OF FZRA WILL FORM FARTHER WEST
BETWEEN 00Z AND 04Z OR SO. GIVEN MODEL PERFORMANCE LATELY...THIS
IS FAR FROM DEFINITE...BUT IS LIKELY ENOUGH TO INCLUDE IN TAFS. AS
THE SURFACE FRONT MOVES FARTHER AWAY...AND HIGH PRESSURE BEGINS TO
TAKE FIRMER CONTROL OF THE REGION...GRADUAL IMPROVEMENT IS
EXPECTED TOMORROW. THE TIMES IN THE TAFS...ESPECIALLY REGARDING
IMPROVEMENT TOMORROW...SHOULD BE TAKEN AS ROUGH ESTIMATES.
PREV DISCUSSION... /ISSUED 307 PM CST SAT JAN 12 2013/
DISCUSSION...
PRECIPITATION IS INCREASING IN A FEW AREAS... SHOWERS AND STORMS
EAST... A WINTRY MIX SOUTH CENTRAL.. CENTRAL AND NORTH CENTRAL
OKLAHOMA... AND VIRGA/SNOW WEST. LOW LEVEL TEMPERATURES WILL COOL
AS PRECIPITATION MOISTENS LOWER LAYERS AND TEMPERATURES APPROACH
WET BULB. THIS WILL BRING THE TEMPERATURE DOWN TO NEAR OR BELOW
FREEZING IN MANY AREAS. MEANWHILE... MID LEVELS ARE DRYING AS
SHORTWAVE MOVES THROUGH THE AREA AS SEEN ON WATER VAPOR LOOP. IN
TIME... THIS WILL REMOVE HIGH RH FROM THE DENDRITIC GROWTH ZONE
TEMPERATURE RANGE USHERING IN A TREND MORE TOWARD FREEZING RAIN
AND FREEZING DRIZZLE. SO ALTHOUGH PRECIPITATION AMOUNTS WILL
GENERALLY BE LIGHT... THE FORECAST OF FREEZING RAIN/FREEZING
DRIZZLE MAY STILL CAUSE ISSUES INTO THE EVENING HOURS ACROSS
CENTRAL AND NORTH CENTRAL OKLAHOMA... SO WILL LEAVE THE WINTER
WEATHER ADVISORY UP. DID NOT GET TOO TRICKY WITH THE PRECIPITATION
TYPES IN THE PACKAGE... KEEPING IT SNOW NORTHWEST... RAIN
SOUTHEAST WHERE TEMPERATURES WILL REMAIN ABOVE FREEZING FOR A
WHILE... AND FREEZING RAIN/SNOW/SLEET IN BETWEEN THESE AREAS.
NAM ALSO SHOWS LOW-LEVEL LIFT REDEVELOPING IN THE 06Z-14Z TIME
FRAME... ESPECIALLY IN THE SOUTHWEST. IF THIS VERIFIES... FREEZING
DRIZZLE WILL BE A POSSIBILITY AFTER MIDNIGHT THROUGH A LITTLE
AFTER SUNRISE. WILL KEEP A SLIGHT CHANCE OF FREEZING DRIZZLE AFTER
MIDNIGHT AND WILL HAVE THE NEXT SHIFTS CONTINUE TO MONITOR THE
TRENDS.
WITH WINTER WEATHER IN THE FIRST PERIOD BEING THE MAJOR WEATHER
IMPACT FOR THIS FORECAST CYCLE... ONLY MADE MINOR ADJUSTMENTS TO
THE FORECAST IN THE LATER PERIODS.
&&
.PRELIMINARY POINT TEMPS/POPS...
OKLAHOMA CITY OK 21 32 17 37 / 50 10 10 10
HOBART OK 18 35 13 36 / 10 0 0 0
WICHITA FALLS TX 24 40 18 40 / 10 10 10 10
GAGE OK 11 30 7 32 / 40 0 0 0
PONCA CITY OK 16 30 10 35 / 70 10 10 10
DURANT OK 28 40 21 43 / 30 10 10 10
&&
.OUN WATCHES/WARNINGS/ADVISORIES...
OK...NONE.
TX...NONE.
&&
$$
04/23
AREA FORECAST DISCUSSION
NWS MORRISTOWN TN
813 PM EST MON JAN 14 2013
.DISCUSSION...UPDATED FORECAST TO ADD FREEZING RAIN INTO THE
CUMBERLAND PLATEAU COUNTIES OF TN AND PART OF SW VA. TEMPERATURES
DURING THE LATE AFTERNOON AND EARLY EVENING HAVE DROPPED MUCH
FASTER THAN EXPECTED INTO THE LOWER TO MID 30S IN PARTS OF
BLEDSOE...MARION...MORGAN AND SCOTT COUNTIES IN TN AND LEE AND WISE
IN VA. ELSEWHERE FARTHER EAST IN THE VALLEY TEMPERATURES HAD
DROPPED INTO THE UPPER 30S BELOW FORECAST LOWS. SHORTWAVE ENERGY
MOVING UP FROM THE SW WILL CONTINUE THE NEXT 3 TO 6 HOURS WITH
LIGHT RAIN OVER THE WESTERN SECTIONS OF THE FORECAST AREA AND
TEMPERATURES IN THE ABOVE COUNTIES STAYING IN THE LOWER 30S. WITH
THE ROADS STILL QUITE WARM FROM THE LAST SEVERAL DAYS OF WARM
WEATHER ICING IS MOST LIKELY ON EXPOSED SURFACES LIKE TREES AND
POWER LINES AND POSSIBLY CARS THAT HAVE SAT OUTSIDE. NORTH WINDS OF
ABOUT 10 MILES PER HOUR WILL MAKE IT FEEL EVEN COLDER. BOTH THE NAM
AND RUC KEEP THIS AREA ON THE EDGE OF THE MEASURABLE PRECIPITATION
SHIELD OVERNIGHT TONIGHT. AS A RESULT HAVE ISSUED A WINTER WEATHER
ADVISORY UNTIL 9Z TUESDAY. FLOOD WATCH WILL BE REISSUED LATER WITH
BEST FLOODING POTENTIAL ACROSS THE SOUTHERN VALLEY AND SOUTHEAST TN
AND SOUTHWEST NC REGION.
&&
.MRX WATCHES/WARNINGS/ADVISORIES...
NC...FLOOD WATCH THROUGH WEDNESDAY MORNING FOR THE FOLLOWING ZONES:
CHEROKEE...CLAY.
TN...FLOOD WATCH THROUGH WEDNESDAY MORNING FOR THE FOLLOWING ZONES:
ANDERSON...BLEDSOE...BLOUNT SMOKY MOUNTAINS...BRADLEY...
CAMPBELL...CLAIBORNE...COCKE SMOKY MOUNTAINS...EAST POLK...
GRAINGER...HAMBLEN...HAMILTON...HANCOCK...HAWKINS...
JEFFERSON...JOHNSON...KNOX...LOUDON...MARION...MCMINN...
MEIGS...MORGAN...NW BLOUNT...NORTH SEVIER...NORTHWEST
CARTER...NORTHWEST COCKE...NORTHWEST GREENE...NORTHWEST
MONROE...RHEA...ROANE...SCOTT TN...SEQUATCHIE...SEVIER
SMOKY MOUNTAINS...SOUTHEAST CARTER...SOUTHEAST GREENE...
SOUTHEAST MONROE...SULLIVAN...UNICOI...UNION...WASHINGTON
TN...WEST POLK.
WINTER WEATHER ADVISORY UNTIL 4 AM EST /3 AM CST/ TUESDAY FOR
THE FOLLOWING ZONES: BLEDSOE...CAMPBELL...CLAIBORNE...
MARION...MORGAN...RHEA...SCOTT TN...SEQUATCHIE.
VA...WINTER WEATHER ADVISORY UNTIL 4 AM EST TUESDAY FOR THE FOLLOWING
ZONES: LEE...WISE.
&&
$$
TD
AREA FORECAST DISCUSSION
NWS NASHVILLE TN
252 PM CST SUN JAN 13 2013
.MESOSCALE UPDATE...
COLD FRONT CRAWLING THROUGH THE MID STATE AT MID-AFTERNOON WITH
COLDER AIR JUST ABOUT ON NASHVILLE. CLARKSVILLE DOWN TO 40 DEGREES
AT 2 PM WITH CROSSVILLE STILL AT 61 DEGREES. LARGE AREA OF RAIN
COVERING THE WEST HALF OF MIDDLE TENNESSEE WITH A GOOD FEED
CONTINUING OUT OF MISSISSIPPI UP INTO MIDDLE TENNESSEE. STILL
HAVE SOME EMBEDDED THUNDERSTORMS AND THEY HAVE BEEN MOSTLY ALONG
THE LEADING EDGE OF THE RAIN AREA. ANOTHER THREE QUARTERS TO AN INCH
OF RAIN LIKELY IN A 75 MILE WIDE CORRIDOR ALONG INTERSTATE 65 OVER
THE NEXT 3 TO 4 HOURS WITH THE RAIN AREA SHIFTING EAST WITH
TIME...BUT SLOWLY. TEMPS WILL REMAIN QUITE WARM OVER EASTERN
MIDDLE TENNESSEE AND PLATEAU INTO THE EVENING BEFORE FRONT
ARRIVES.
BOYD
&&
.PREV DISCUSSION... /ISSUED 128 PM CST SUN JAN 13 2013/
DISCUSSION...
BULK OF THE RAIN TODAY HAS BEEN OVER THE WESTERN HALF THE MID
STATE WITH SEVERAL FLASH FLOOD WARNINGS BEING ISSUED. THE RIVERS
HAVE RESPONDED QUITE WELL BY CARRYING THE RUNOFF DURING THE DAY
WITH THE HARPETH AT KINGSTON SPRING BEING THE ONLY RIVER AT TIME
OF THIS WRITING THAT HAS JUMPED TO THE 14 FOOT LEVEL WHICH IS
STILL WELL BELOW THE FLOOD STAGE OF 20 FEET. THE HARPETH IS
CONTINUING TO RISE AND IS FORECAST TO REACH THE 20 FOOT LEVEL
AROUND DAYBREAK MONDAY.
SYNOPICALLY THE FRONT EXTENDED FROM JUST WEST OF BOWLING GREEN
DOWN BETWEEN NASHVILLE AND CLARKSVILLE TO TUPELO MISSISSIPPI. THE
FRONT HAS A SERIES OF WAVES THAT WILL RIDE UP THE FRONT DURING THE
AFTERNOON AND EARLY EVENING AND THIS WILL KEEP THE FRONT IN THE
MID STATE A LITTLE LONGER THAN PREVIOUSLY THROUGHT. EVENTUALLY THE
FRONT WILL WORK EASTWARD AND BE ALONG THE PLATEAU AROUND 00Z BASED
ON THE LATEST RUC RUN. MUCH OF THE RAIN IS POST FRONTAL. WILL KEEP
HIGH POPS GOING THROUGH THE EVENING ACROSS ALL OF THE MID STATE
AND THEN LOWER THE POPS FROM THE WEST AFTER MIDNIGHT. MUCH COLDER
TEMPERATURES TONIGHT AND MONDAY AND I HAVE PLACE A MIX OF RAIN AND
SLEET OVER THE NORTHWEST HALF OF THE MID STATE AFTER MIDNIGHT AND
OVER THE NORTH HALF DURING THE DAY MONDAY. MONDAY WILL BE A COLD DAY
WITH HIGHS IN THE 30S. WAVES ALONG THE FRONTAL BOUNDARY TO OUR
SOUTH WILL KEEP PRECIP CHANCES GOING THROUGH TUESDAY NIGHT.
WEDNESDAY THROUGH THE REMAINDER OF THE WEEK LOOKS BASICALLY DRY AS
HIGH PRESSURE REMAINS OVER THE AREA INTO THE WEEKEND. A SYSTEM DOES
DEVELOP IN THE GULF ON THURSDAY BUT THINK IT WILL REMAIN FAR
ENOUGH SOUTH NOT TO BRING PRECIP TO THE MID STATE.
&&
.OHX WATCHES/WARNINGS/ADVISORIES...
FLASH FLOOD WATCH THROUGH LATE TONIGHT FOR TNZ005>011-022>034-
056>066-075-077>080-093>095.
&&
$$
BOYD
AREA FORECAST DISCUSSION
NWS NASHVILLE TN
128 PM CST SUN JAN 13 2013
.DISCUSSION...
BULK OF THE RAIN TODAY HAS BEEN OVER THE WESTERN HALF THE MID
STATE WITH SEVERAL FLASH FLOOD WARNINGS BEING ISSUED. THE RIVERS
HAVE RESPONDED QUITE WELL BY CARRYING THE RUNOFF DURING THE DAY
WITH THE HARPETH AT KINGSTON SPRING BEING THE ONLY RIVER AT TIME
OF THIS WRITING THAT HAS JUMPED TO THE 14 FOOT LEVEL WHICH IS
STILL WELL BELOW THE FLOOD STAGE OF 20 FEET. THE HARPETH IS
CONTINUING TO RISE AND IS FORECAST TO REACH THE 20 FOOT LEVEL
AROUND DAYBREAK MONDAY.
SYNOPICALLY THE FRONT EXTENDED FROM JUST WEST OF BOWLING GREEN
DOWN BETWEEN NASHVILLE AND CLARKSVILLE TO TUPELO MISSISSIPPI. THE
FRONT HAS A SERIES OF WAVES THAT WILL RIDE UP THE FRONT DURING THE
AFTERNOON AND EARLY EVENING AND THIS WILL KEEP THE FRONT IN THE
MID STATE A LITTLE LONGER THAN PREVIOUSLY THROUGHT. EVENTUALLY THE
FRONT WILL WORK EASTWARD AND BE ALONG THE PLATEAU AROUND 00Z BASED
ON THE LATEST RUC RUN. MUCH OF THE RAIN IS POST FRONTAL. WILL KEEP
HIGH POPS GOING THROUGH THE EVENING ACROSS ALL OF THE MID STATE
AND THEN LOWER THE POPS FROM THE WEST AFTER MIDNIGHT. MUCH COLDER
TEMPERATURES TONIGHT AND MONDAY AND I HAVE PLACE A MIX OF RAIN AND
SLEET OVER THE NORTHWEST HALF OF THE MID STATE AFTER MIDNIGHT AND
OVER THE NORTH HALF DURING THE DAY MONDAY. MONDAY WILL BE A COLD DAY
WITH HIGHS IN THE 30S. WAVES ALONG THE FRONTAL BOUNDARY TO OUR
SOUTH WILL KEEP PRECIP CHANCES GOING THROUGH TUESDAY NIGHT.
WEDNESDAY THROUGH THE REMAINDER OF THE WEEK LOOKS BASICALLY DRY AS
HIGH PRESSURE REMAINS OVER THE AREA INTO THE WEEKEND. A SYSTEM DOES
DEVELOP IN THE GULF ON THURSDAY BUT THINK IT WILL REMAIN FAR
ENOUGH SOUTH NOT TO BRING PRECIP TO THE MID STATE.
&&
.PRELIMINARY POINT TEMPS/POPS...
NASHVILLE 30 37 28 44 / 70 30 40 40
CLARKSVILLE 24 33 24 41 / 70 30 20 20
CROSSVILLE 36 43 33 45 / 100 70 70 70
COLUMBIA 31 38 29 44 / 70 50 40 40
LAWRENCEBURG 32 38 30 44 / 100 70 40 40
WAVERLY 25 35 25 40 / 70 30 20 20
&&
.OHX WATCHES/WARNINGS/ADVISORIES...
FLASH FLOOD WATCH THROUGH LATE TONIGHT FOR TNZ005>011-022>034-
056>066-075-077>080-093>095.
&&
$$
BOYD
AREA FORECAST DISCUSSION...UPDATED
NWS FORT WORTH TX
1200 PM CST SUN JAN 13 2013
.UPDATE...
AN UPDATE WAS SENT AT MID MORNING REMOVING THE PRECIPITATION FROM
TODAYS FORECAST. SKIES HAVE NEARLY CLEARED ACROSS ALL BUT THE
SOUTHEASTERN COUNTIES AS OF 1730Z. HAVE JUST SENT ANOTHER QUICK
UPDATE TO ADJUST THE HOURLY TRENDS.
58
&&
.AVIATION...
NORTHWESTERLY WINDS AROUND 10 TO 20 KNOTS WILL CONTINUE FOR MOST
OF THE PERIOD...BECOMING NORTHERLY TOMORROW. MOSTLY CLEAR SKIES
WILL PREVAIL FOR MOST OF THE PERIOD...BUT SCT/BKN MID CLOUDS ARE
POSSIBLE TOMORROW AS A DISTURBANCE PASSES OVER NORTH TEXAS. NO
PRECIPITATION IS EXPECTED...DUE TO VERY DRY AIR IN THE LOWER
ATMOSPHERE.
HAMPSHIRE
&&
.PREV DISCUSSION... /ISSUED 425 AM CST SUN JAN 13 2013/
SHORT TERM WINTER WEATHER/FORECAST CONCERNS...
DID NOT MAKE ANY SIGNIFICANT CHANGES TO THE FORECAST FROM THE 139
AM CST FORECAST UPDATE/AFD. THERE IS STILL NO MODEL GUIDANCE THAT
HAS A GOOD HANDLE ON WINTRY PRECIPITATION FALLING NORTHWEST OF THE
METROPLEX EARLY THIS MORNING. THE HRRR IS CLOSEST...BUT DOESNT
SEEM TO KNOW WHAT IS CAUSING THE WINTRY PRECIPITATION. THE HRRR
CONSISTENTLY INITIALIZES THE RADAR RETURNS AND THEN ALLOWS THEM TO
DISSIPATE SHORTLY THEREAFTER WHICH IS A GOOD SIGN THAT THE MODEL
IS NOT RESOLVING THE FORCING MECHANISM THAT IS RESPONSIBLE FOR THE
PRESENCE OF THE PRECIPITATION. AT ANY RATE...DRAWING BACK ON
MORNING UPDATE DISCUSSIONS...THE GFS FORECAST THAT H700 CONFLUENCE
WOULD DISSIPATE EARLY THIS MORNING SEEMS TO BE SPOT ON ACCORDING
TO REGIONAL VWP OUTPUT. THE BEST H700 CONFLUENCE HAD MOVED NORTH
OF THE RED RIVER AS OF 09Z...AND LIGHT WINTRY PRECIPITATION WAS
LIFTING NORTHEAST AS WELL. THERE IS STILL SOME CONCERN FOR H800
FRONTOGENETIC FORCING ALONG A SHERMAN TO FORT WORTH TO GRANBURY
LINE AROUND SUNRISE RESULTING IN SOME SHALLOW CONVECTION
INITIATION. THE GFS CONTINUES TO ADVERTISE THIS FORCING FOR
ASCENT NEAR THE H800 LEVEL WITH A 100 MB LAYER ABOVE IT
CHARACTERIZED BY DECREASING THETA-E TEMPERATURES WITH
HEIGHT (ESSENTIALLY POSITIVE CAPE).
THAT SAID...THERE IS NO OBSERVATIONAL EVIDENCE THAT STRONG LIFT IS
OCCURRING AT THIS TIME AS THERE ARE NO RAPIDLY COOLING CLOUD TOPS
OR LIGHT MID-LEVEL RADAR REFLECTIVITY RETURNS OVER THESE AREAS AT
THE TIME OF THIS DISCUSSION. THEREFORE WILL NOT BE ISSUING A
FREEZING RAIN ADVISORY FROM SHERMAN...THROUGH THE DFW METROPLEX
AND SOUTHWEST TOWARDS GRANBURY AT THIS TIME. OF COURSE WE WILL
CONTINUE TO MONITOR THIS SITUATION CLOSELY THROUGH SUNRISE AS ANY
DEVELOPING PRECIPITATION WILL LIKELY BE COMPOSED OF SUPERCOOLED
WATER. WHILE THIS WOULD FALL IN LIQUID FORM...IT WOULD FREEZE
IMMEDIATELY UPON CONTACT WITH ANY SURFACE THAT IS ALSO AT OR BELOW
FREEZING. AT THIS TIME IT LOOKS AS THOUGH MOST PRECIPITATION
DEVELOPMENT WILL REMAIN SOUTHEAST OF THIS LINE THROUGH
SUNRISE...DIMINISHING THE THREAT FOR FREEZING RAIN OR SLEET.
TODAY THROUGH MONDAY...ALL GUIDANCE INDICATES THAT LOW-LEVEL
FRONTOGENETIC FORCING WILL DIMINISH IN INTENSITY THIS MORNING AS
DRY AIR AND SUBSIDENCE CONTINUE TO SLOWLY WORK INTO THE REGION.
DRY AIR NEAR THE SURFACE HAS ALREADY PENETRATED AS FAR SOUTHEAST
AS AN ATHENS TO TEMPLE LINE...BUT IT IS THE MOISTURE ALOFT THAT WE
HAVE TO WORRY ABOUT EARLY THIS MORNING. EXPECT ALL LIGHT RAIN/RAIN
SHOWERS TO MOVE EAST AFTER 18Z. DID KEEP IN A 20 PERCENT CHANCE
FOR A RAIN/SLEET MIX FOR LOCATIONS ALONG AND NORTH OF A
GAINESVILLE TO MCKINNEY TO COOPER LINE AFTER SUNRISE JUST IN CASE
THE H800 FRONTOGENESIS SCENARIO DESCRIBED ABOVE PANS OUT. THESE
LOCATIONS WOULD ALSO HAVE TO BE INCLUDED IN A BRIEF FREEZING RAIN
ADVISORY IF THIS PRECIPITATION DOES MANAGE TO DEVELOP AROUND/JUST
BEFORE SUNRISE. IF IT DOES NOT...THESE AREAS WILL LIKELY REMAIN
DRY THIS MORNING.
WE SHOULD SEE SOME SUNSHINE BY LATE THIS AFTERNOON...HOWEVER NOT
MUCH OF A WARM-UP IS EXPECTED TODAY AS NORTH WINDS AND MORNING
CLOUD COVER HELP TO KEEP TEMPERATURES IN THE LOWER TO MID 40S FOR
HIGHS FOR MOST LOCATIONS. FOR TONIGHT...ANOTHER STRONG SHORTWAVE
TROUGH IS EXPECTED TO MOVE OVER THE SOUTH PLAINS. THIS TROUGH WAS
OVER THE SOUTHERN CA COAST PER EARLY MORNING WATER VAPOR IMAGERY.
THIS TROUGH HAS A WELL-DEFINED CYCLONIC CIRCULATION IN WATER VAPOR
IMAGERY AND IS PROGGED TO SEND STRONG LARGE SCALE FORCING FOR
ASCENT OVER THE REGION AS IT MOVES NORTHEAST TONIGHT AND INTO
MONDAY MORNING.
FOR MOST OF NORTH TX...THIS STRONG FORCING FOR ASCENT IS EXPECTED
TO GO UNNOTICED AS DRY AIR AND SUBSIDENCE ARE EXPECTED TO HAVE
LEFT THE ATMOSPHERE RELATIVELY STABLE BY LATE TONIGHT.
HOWEVER...THE GFS/NAM/ECMWF ALL SHOW RELATIVELY STRONG AND
PERSISTENT ISENTROPIC LIFT ON THE 305 K SURFACE IN BETWEEN 06 AND
12Z MONDAY MORNING OVER THE FAR SOUTHEASTERN COUNTIES OF THE CWA.
MODELS DO NOT SHOW MUCH IN THE WAY OF QPF...HOWEVER MID-LEVEL
MOISTURE WILL LIKELY RESIDE NEAR THE GULF COAST BEFORE THIS TROUGH
MOVES OVER THE REGION TONIGHT. IT SEEMS REASONABLE THAT SOME OF
THIS MOISTURE WILL RETURN ON THE 305K SURFACE (NEAR THE H700 LEVEL
TONIGHT) AND RESULT IN SOME PERSISTENT MID-LEVEL PRECIPITATION
PRODUCTION BEFORE SUNRISE MONDAY.
THE LOWER TROPOSPHERE IS EXPECTED TO BE QUITE DRY BEFORE THIS
PROCESS STARTS...SO A SIGNIFICANT AMOUNT OF THIS MID-LEVEL
PRECIPITATION IS LIKELY TO EVAPORATE BEFORE REACHING THE GROUND.
REGARDLESS...CONFIDENCE IN THE MID-LEVEL PRECIPITATION PRODUCTION
IS HIGH...SO WENT AHEAD AND MENTIONED A 20 PERCENT CHANCE OF RAIN
OR FREEZING RAIN SOUTHEAST OF AN ATHENS TO TEMPLE LINE (NOT
INCLUDING WACO AT THIS TIME) FOR EARLY MONDAY MORNING. DO NOT
THINK THE IMPACTS OF THIS WILL BE HIGH UNLESS THE LOWER ATMOSPHERE
SATURATES QUICKER THAN EXPECTED. LIGHT PRECIPITATION WILL LIKELY
CONTINUE AFTER SUNRISE MONDAY MORNING FOR THESE
LOCATIONS...HOWEVER TEMPERATURES ARE LIKELY TO WARM ABOVE FREEZING
AFTER SUNRISE. WE MAY HAVE TO CONSIDER A WINTER WEATHER OR
FREEZING RAIN ADVISORY IF IT LOOKS LIKE MORE PRECIPITATION WILL
MAKE IT TO THE GROUND...BUT CONFIDENCE IS TOO LOW TO GO WITH
ANYTHING AT THIS TIME.
FOR MID-WEEK...THE ECMWF HAS COME MORE IN LINE WITH THE NAEFS
SOLUTION INDICATING THAT THE LONGWAVE TROUGH OVER THE WESTERN
THIRD OF THE CONUS WILL CONSOLIDATE AND MOVE EAST AS A POSITIVELY
TILTED TROUGH TUESDAY NIGHT INTO WEDNESDAY. THIS SOLUTION LIMITS
LARGE SCALE FORCING FOR ASCENT OVER NORTH AND CENTRAL TX BY
KEEPING LOW LEVEL FLOW VEERED AS IT MOVES OVER THE AREA. THIS
WOULD ALSO PREVENT ANY SIGNIFICANT MOISTURE FROM RETURNING TO THE
REGION OUT AHEAD OF THIS UPPER TROUGH. THE 00 AND 06Z NAM
SOLUTIONS BOTH PREFER THE STRONG AND SLOW MOVING CUT-OFF LOW
SOLUTION ADVERTISED BY THE ECMWF THE PAST FEW DAYS. WHILE THIS
SOLUTION IS AN OUTLIER SOLUTION...WE WILL CONTINUE TO WATCH FOR
ANY SIGN THAT THIS SOLUTION COULD VERIFY AS IT WOULD LIKELY ALLOW
FOR A SIGNIFICANT ICE STORM IN THE REGION IF IT VERIFIED. THIS
FORECAST CONTINUES TO SIDE WITH THE CONSENSUS OF THE NAEFS AND THE
13/00Z ECMWF AS THIS IS BY FAR THE MOST LIKELY OUTCOME. HOWEVER
WILL NOT COMPLETELY IGNORE THE NAM AS IT WOULD BRING A HIGH IMPACT
WINTER WEATHER EVENT TO SOME PART OF NORTH OR CENTRAL TX.
EXTENDED...ONCE THE LONGER WAVE TROUGH MOVES OUT OF THE
REGION...WE SHOULD SEE A SLOW WARMING TREND FOR THE REGION AS A
BLOCKING RIDGE SETS UP OVER THE WESTERN CONUS COAST KEEPING MORE
OR LESS NORTHWEST AND CONFLUENT FLOW OVER THE SOUTH PLAINS. THIS
WARM UP COULD COME TO AN ABRUPT END EARLY NEXT WEEK AS BOTH THE
GFS AND THE ECMWF HAVE A STRONG COLD FRONT MOVING SOUTH THROUGH
THE GREAT PLAINS. THE GFS COOLS US DOWN...BUT ALLOWS THE COLD AIR
TO MODIFY TO THE POINT THAT IT BEHAVES LIKE A TYPICAL WINTER COLD
FRONT FOR TEXAS. THAT IS WE COOL DOWN SIGNIFICANTLY...BUT
OVERNIGHT LOWS TEND TO SAY IN THE MID TO UPPER 20S WHILE HIGHS
CLIMB ABOVE FREEZING.
THE ECMWF BRINGS A SIGNIFICANT ARCTIC OUTBREAK SOUTH THROUGH THE
PLAINS...WHICH WOULD IMPACT NORTH TX SUNDAY NIGHT OR MONDAY IF IT
VERIFIED. THE 13/00Z ECMWF HAS A 1053 MB (MSLP) SURFACE HIGH
BARRELING SOUTH INTO THE CENTRAL PLAINS BEHIND THIS FRONT...WHICH
IS A SIGN OF A VERY COLD ARCTIC AIR INVASION OF THE PLAINS. THIS
IS NOT THE MOST LIKELY SOLUTION TO VERIFY AT THIS TIME...BUT IT
BEARS WATCHING AS WE GET CLOSER TO NEXT WEEKEND AND EARLY NEXT
WEEK. THE ECMWF WOULD BRING LOWS DOWN INTO THE TEENS IF NOT LOWER
ACROSS NORTH TX WHICH COULD CERTAINLY HAVE A BIG IMPACT ON THE
REGION. THIS IS SLIGHTLY BEYOND THE OFFICIAL FORECAST PERIOD AT
THIS TIME...SO WILL WATCH FOR MORE CONSISTENCY AMONGST MODELS
BEFORE JUMPING ON AN ARCTIC OUTBREAK TO START OFF THE NEXT WORK
WEEK.
CAVANAUGH
&&
.PRELIMINARY POINT TEMPS/POPS...
DALLAS-FT. WORTH, TX 42 26 44 28 45 / 10 10 5 10 10
WACO, TX 45 27 43 27 45 / 10 10 10 10 10
PARIS, TX 42 25 44 26 43 / 30 10 10 10 10
DENTON, TX 42 24 43 23 45 / 10 10 5 10 10
MCKINNEY, TX 42 24 44 24 43 / 30 10 10 10 10
DALLAS, TX 42 27 44 29 44 / 10 10 10 10 10
TERRELL, TX 44 26 43 27 43 / 20 10 10 10 10
CORSICANA, TX 44 28 44 30 43 / 10 10 10 10 10
TEMPLE, TX 46 27 43 27 44 / 10 10 10 10 10
MINERAL WELLS, TX 42 22 43 22 44 / 5 10 5 5 10
&&
.FWD WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
85/58
AREA FORECAST DISCUSSION
NWS LUBBOCK TX
1121 AM CST SUN JAN 13 2013
.AVIATION...
VFR CONDITIONS EXPECTED DURING THE DAY TODAY AS LIGHT NORTHERLY
WINDS VEER TO A MORE EASTERLY COMPONENT BY TONIGHT. IT IS
THEREFORE POSSIBLE FOR FEW MVFR CLOUD DECKS TO FORM TONIGHT...ALTHOUGH
THE SIGNAL FOR THIS OCCURRENCE DOES NOT APPEAR TO BE OVERLY
STRONG. HAVE OPTED TO CONTINUE A MENTION IN THE TAF AND WILL OF
COURSE AMEND AS NECESSARY. ALSO TONIGHT...AN UPPER LEVEL WEAK
DISTURBANCE MOVING ACROSS THE REGION MAY PROMOTE A CHANCE FOR
FLURRIES/-SN JUST WEST OF KLBB. CONFIDENCE OF THIS HAPPENING AT
ALL IS LOW AND WILL THEREFORE NOT ADD A PRECIP MENTION ATTM.
&&
PREV DISCUSSION... /ISSUED 354 AM CST SUN JAN 13 2013/
SHORT TERM...
A SPRAWLING AND COMPLEX UPPER LEVEL TROUGH WAS DOMINATING THE
WESTERN 2/3RDS OF THE CONUS...WITH SEVERAL EMBEDDED DISTURBANCES
NOTED WITHIN IT. ONE SUCH SHORTWAVE TROUGH WAS GRAZING THE AREA
EARLY THIS MORNING...WITH ANOTHER CURRENTLY DIVING DOWN THE SOUTHERN
CALIFORNIA COAST PROGGED TO APPROACH FROM THE WEST LATE TONIGHT. THE
FORMER HAS PROVIDED STRONG ENOUGH LIFT TO PRODUCE A BAND OF SNOW
THAT HAS TRAVERSED THE NORTHWEST AND NORTH-CENTRAL ZONES EARLY THIS
MORNING. EVEN THOUGH THE PRESENTATION ON RADAR WITHIN THIS BAND HAS
NOT BEEN OVERLY IMPRESSIVE AND MOISTURE IS RATHER LIMITED...THE BAND
HAS BEEN ABLE TO SQUEEZE OUT EFFICIENT SNOW RATES GIVEN THE COLD
TEMPERATURES AND HIGH SNOW TO LIQUID RATIOS. FRIONA REPORTED A QUICK
1-2 INCHES OF SNOW AS THE BAND MOVED THROUGH EARLIER THIS
MORNING...WITH DIMMITT AND TULIA REPORTING LESS THAN 1 INCH. LIFT
SUPPORTING THIS BAND WILL GRADUALLY WANE MOVING TOWARDS
DAYBREAK...BUT A LITTLE LIGHT SNOW OR FLURRIES COULD LINGER PAST 12Z
ACROSS THE NORTHEAST ZONES.
OTHERWISE...COLD SFC RIDGING WILL DOMINATE THE REGION THROUGH THE
SHORT TERM. LOW STRATUS CLOUDS HAVE DEVELOPED ACROSS ROUGHLY THE
NORTHWEST HALF OF THE CWA IN THIS REGIME EARLY THIS MORNING. BOTH
THE NAM AND GFS SUGGEST THESE CLOUDS WILL QUICKLY SCATTER OUT THIS
MORNING AS MID- AND UPPER-LEVEL SUBSIDENCE INCREASES IN THE WAKE OF
THE PASSING SHORTWAVE TROUGH. ON THE OTHER HAND...THE RUC AND HRRR
SUGGEST THAT THE LOW CLOUDS MAY HANG ON MUCH OR ALL OF THE DAY ON
THE CAPROCK AS WINDS VEER EASTERLY AND THE SHALLOW BUT RELATIVELY
MOIST UPSLOPE FLOW ENSUES. CURRENT FORECAST IN THE GRIDS DOES
INDICATE CLEARING SKIES BY MIDDAY...BUT IF THIS DOES NOT
OCCUR...FORECAST HIGHS WILL LIKELY BE TOO HIGH. REGARDLESS...IT WILL
BE A CHILLY DAY AND HAVE FAVORED THE LOW SIDE OF MOS GUIDANCE WITH
FORECAST HIGHS IN THE LOWER TO MIDDLE 30S FOR ALL BUT THE NORTHWEST
ZONES WHERE UPPER 20S WERE CARRIED.
CHILLY EASTERLY UPSLOPE FLOW WILL CONTINUE THROUGH TONIGHT. PROGGED
SOUNDINGS INDICATE MOSTLY CLEAR SKIES EARLY ON...WITH SOME MID-LEVEL
CLOUDS VISITING AT LEAST THE NORTHWEST ZONES LATE AS THE NEXT
SHORTWAVE TROUGH RACES BY. HOWEVER...GIVEN THE UPSLOPE FLOW WOULD
NOT BE SURPRISED IF SOME LOWER CLOUDS DEVELOP OR PERSIST. ALTHOUGH
MODELS ARE GENERALLY DRY...THINK THERE MAY BE ENOUGH LIFT AND
MOISTURE TO SQUEEZE OUT A FEW FLURRIES ACROSS THE WESTERN ZONES LATE
TONIGHT AND HAVE INSERTED THIS INTO THE FORECAST. EXTENT AND
DURATION OF ANY CLOUD COVER COULD HAVE SOME IMPACTS ON EXACTLY HOW
COLD IT GETS TONIGHT...BUT EITHER WAY IT WILL BE CHILLY AND HAVE
MAINTAINED LOWS 10-15 DEGREES BELOW MID-JANUARY AVERAGES /RANGING
FROM 9 DEGREES NORTHWEST TO MID-TEENS OUT EAST/.
LONG TERM...
THE MON THRU THU FORECAST HINGES ON THE STRENGTH AND TRACK OF THE
SRN PORTION OF THE UPPER-LEVEL TROUGH...INITIALLY LOCATED OVER AZ
AND NM MONDAY MORNING. THE MAJORITY OF GUIDANCE ELONGATES THE TROUGH
FROM THE SW TO NE AS IT SLIDES SEWD ACROSS WEST TEXAS...WITH
MOISTURE AND LIFT BOTH LACKING TO WRING OUT ANY PRECIPITATION FOR
OUR AREA...BEFORE IT EVENTUALLY CLOSES OFF AT 500 MB ACROSS NORTH
CENTRAL TX. HOWEVER...THERE ARE STILL A FEW MODELS /E.G. 0Z NAM
AND CMC/ AND SOME GEFS ENSEMBLE MEMBERS THAT CLOSED OFF TROUGH
INTO A CUTOFF LOW ACROSS SRN NM OR NRN MX...THEN TRACK IT SLOWLY
EAST ACROSS WEST TEXAS MID-WEEK. IN THE LATTER CASE COULD BRING
A CHANCE OF SOME RAIN OR SNOW IN THE TUE THRU THU TIME FRAME AS
BOTH MOISTURE ADVECTION AND LIFT WOULD BE ENHANCED. BUT
PREPONDERANCE OF GUIDANCE SUGGESTS THE OPEN WAVE PASSAGE
ACCOMPANIED BY ONLY AN INCREASE IN MID-LVL CLOUD COVER. THUS WE/VE
KEPT POPS BELOW MENTION THROUGH THE EXTENDED PERIOD...ALTHOUGH
NUDGED THEM UP TO 10 PERCENT ACROSS OUR SRN ZONES. MONDAY STILL
APPEARS TO BE THE COOLEST DAY IN THE PERIOD...WITH HIGHS ONLY IN
THE LOW TO MID 30S. TUESDAY WILL ONLY BE SLIGHTLY WARMER...WITH
HIGHS IN THE UPPER 30S TO LOW 40S. FINALLY...BARRING THE CLOSED
LOW SOLUTION...HIGHS WILL WARM BACK INTO THE UPPER 40S AND 50S WED
AND THU.
FRI-SAT: AFTER THE TROUGH/LOW PASSES...WEAK ZONAL TO SW FLOW SHOULD
EXTEND OVER THE AREA AS A BROAD LOW-AMPLITUDE TROUGH DEVELOPS OVER
THE DESERT SOUTHWEST. SOME SUB-TROPICAL MOISTURE MAY GET DRAWN UP BY
THE TROUGH TO BRING SOME HIGH CLOUD COVER TO THE AREA BY FRIDAY. AND
JUST TO OUR NORTH...UPPER FLOW WILL BECOME CYCLONIC AS A DEEP
TROUGH DROPS INTO THE GREAT LAKES REGION...WHILE THE UPPER RIDGE
RE-AMPLIFIES ALONG THE PACIFIC COAST. TEMPS WILL CONTINUE TO BE
MILD WITH HIGHS MAINLY IN THE MID TO UPPER 50S.
A WEAK FRONT IS EXPECTED TO MOVE INTO THE AREA BY SUNDAY...RESULTING IN
A MODEST COOL DOWN DEPENDING ON THE TIMING OF THE FROPA. A MUCH
STRONGER FRONT IS POSSIBLE BY MONDAY THE 21ST...AS A 1050MB SFC RIDGE
DIVES OUT OF CENTRAL CANADA INTO THE PLAINS. IT IS STILL TOO EARLY
TO TELL IF THIS COLD AIR MASS WILL SETTLE INTO WEST TEXAS OR IF
WE/LL ONLY RECEIVE A GLANCING BLOW.
&&
.PRELIMINARY POINT TEMPS/POPS...
FRIONA 28 9 29 9 37 / 10 10 10 10 10
TULIA 29 10 30 12 38 / 0 0 10 10 10
PLAINVIEW 31 11 31 11 38 / 10 10 10 10 10
LEVELLAND 34 11 32 12 38 / 10 10 10 10 10
LUBBOCK 33 12 33 13 39 / 10 10 0 10 10
DENVER CITY 36 13 32 12 38 / 10 10 10 10 10
BROWNFIELD 36 12 32 13 38 / 10 10 0 10 10
CHILDRESS 35 15 34 15 41 / 0 0 0 0 10
SPUR 35 14 34 15 40 / 0 0 0 0 10
ASPERMONT 37 16 36 14 41 / 0 0 10 0 10
&&
.LUB WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
29
AREA FORECAST DISCUSSION
NWS FORT WORTH TX
1106 AM CST SUN JAN 13 2013
.AVIATION...
NORTHWESTERLY WINDS AROUND 10 TO 20 KNOTS WILL CONTINUE FOR MOST
OF THE PERIOD...BECOMING NORTHERLY TOMORROW. MOSTLY CLEAR SKIES
WILL PREVAIL FOR MOST OF THE PERIOD...BUT SCT/BKN MID CLOUDS ARE
POSSIBLE TOMORROW AS A DISTURBANCE PASSES OVER NORTH TEXAS. NO
PRECIPITATION IS EXPECTED...DUE TO VERY DRY AIR IN THE LOWER
ATMOSPHERE.
HAMPSHIRE
&&
.PREV DISCUSSION... /ISSUED 425 AM CST SUN JAN 13 2013/
SHORT TERM WINTER WEATHER/FORECAST CONCERNS...
DID NOT MAKE ANY SIGNIFICANT CHANGES TO THE FORECAST FROM THE 139
AM CST FORECAST UPDATE/AFD. THERE IS STILL NO MODEL GUIDANCE THAT
HAS A GOOD HANDLE ON WINTRY PRECIPITATION FALLING NORTHWEST OF THE
METROPLEX EARLY THIS MORNING. THE HRRR IS CLOSEST...BUT DOESNT
SEEM TO KNOW WHAT IS CAUSING THE WINTRY PRECIPITATION. THE HRRR
CONSISTENTLY INITIALIZES THE RADAR RETURNS AND THEN ALLOWS THEM TO
DISSIPATE SHORTLY THEREAFTER WHICH IS A GOOD SIGN THAT THE MODEL
IS NOT RESOLVING THE FORCING MECHANISM THAT IS RESPONSIBLE FOR THE
PRESENCE OF THE PRECIPITATION. AT ANY RATE...DRAWING BACK ON
MORNING UPDATE DISCUSSIONS...THE GFS FORECAST THAT H700 CONFLUENCE
WOULD DISSIPATE EARLY THIS MORNING SEEMS TO BE SPOT ON ACCORDING
TO REGIONAL VWP OUTPUT. THE BEST H700 CONFLUENCE HAD MOVED NORTH
OF THE RED RIVER AS OF 09Z...AND LIGHT WINTRY PRECIPITATION WAS
LIFTING NORTHEAST AS WELL. THERE IS STILL SOME CONCERN FOR H800
FRONTOGENETIC FORCING ALONG A SHERMAN TO FORT WORTH TO GRANBURY
LINE AROUND SUNRISE RESULTING IN SOME SHALLOW CONVECTION
INITIATION. THE GFS CONTINUES TO ADVERTISE THIS FORCING FOR
ASCENT NEAR THE H800 LEVEL WITH A 100 MB LAYER ABOVE IT
CHARACTERIZED BY DECREASING THETA-E TEMPERATURES WITH
HEIGHT (ESSENTIALLY POSITIVE CAPE).
THAT SAID...THERE IS NO OBSERVATIONAL EVIDENCE THAT STRONG LIFT IS
OCCURRING AT THIS TIME AS THERE ARE NO RAPIDLY COOLING CLOUD TOPS
OR LIGHT MID-LEVEL RADAR REFLECTIVITY RETURNS OVER THESE AREAS AT
THE TIME OF THIS DISCUSSION. THEREFORE WILL NOT BE ISSUING A
FREEZING RAIN ADVISORY FROM SHERMAN...THROUGH THE DFW METROPLEX
AND SOUTHWEST TOWARDS GRANBURY AT THIS TIME. OF COURSE WE WILL
CONTINUE TO MONITOR THIS SITUATION CLOSELY THROUGH SUNRISE AS ANY
DEVELOPING PRECIPITATION WILL LIKELY BE COMPOSED OF SUPERCOOLED
WATER. WHILE THIS WOULD FALL IN LIQUID FORM...IT WOULD FREEZE
IMMEDIATELY UPON CONTACT WITH ANY SURFACE THAT IS ALSO AT OR BELOW
FREEZING. AT THIS TIME IT LOOKS AS THOUGH MOST PRECIPITATION
DEVELOPMENT WILL REMAIN SOUTHEAST OF THIS LINE THROUGH
SUNRISE...DIMINISHING THE THREAT FOR FREEZING RAIN OR SLEET.
TODAY THROUGH MONDAY...ALL GUIDANCE INDICATES THAT LOW-LEVEL
FRONTOGENETIC FORCING WILL DIMINISH IN INTENSITY THIS MORNING AS
DRY AIR AND SUBSIDENCE CONTINUE TO SLOWLY WORK INTO THE REGION.
DRY AIR NEAR THE SURFACE HAS ALREADY PENETRATED AS FAR SOUTHEAST
AS AN ATHENS TO TEMPLE LINE...BUT IT IS THE MOISTURE ALOFT THAT WE
HAVE TO WORRY ABOUT EARLY THIS MORNING. EXPECT ALL LIGHT RAIN/RAIN
SHOWERS TO MOVE EAST AFTER 18Z. DID KEEP IN A 20 PERCENT CHANCE
FOR A RAIN/SLEET MIX FOR LOCATIONS ALONG AND NORTH OF A
GAINESVILLE TO MCKINNEY TO COOPER LINE AFTER SUNRISE JUST IN CASE
THE H800 FRONTOGENESIS SCENARIO DESCRIBED ABOVE PANS OUT. THESE
LOCATIONS WOULD ALSO HAVE TO BE INCLUDED IN A BRIEF FREEZING RAIN
ADVISORY IF THIS PRECIPITATION DOES MANAGE TO DEVELOP AROUND/JUST
BEFORE SUNRISE. IF IT DOES NOT...THESE AREAS WILL LIKELY REMAIN
DRY THIS MORNING.
WE SHOULD SEE SOME SUNSHINE BY LATE THIS AFTERNOON...HOWEVER NOT
MUCH OF A WARM-UP IS EXPECTED TODAY AS NORTH WINDS AND MORNING
CLOUD COVER HELP TO KEEP TEMPERATURES IN THE LOWER TO MID 40S FOR
HIGHS FOR MOST LOCATIONS. FOR TONIGHT...ANOTHER STRONG SHORTWAVE
TROUGH IS EXPECTED TO MOVE OVER THE SOUTH PLAINS. THIS TROUGH WAS
OVER THE SOUTHERN CA COAST PER EARLY MORNING WATER VAPOR IMAGERY.
THIS TROUGH HAS A WELL-DEFINED CYCLONIC CIRCULATION IN WATER VAPOR
IMAGERY AND IS PROGGED TO SEND STRONG LARGE SCALE FORCING FOR
ASCENT OVER THE REGION AS IT MOVES NORTHEAST TONIGHT AND INTO
MONDAY MORNING.
FOR MOST OF NORTH TX...THIS STRONG FORCING FOR ASCENT IS EXPECTED
TO GO UNNOTICED AS DRY AIR AND SUBSIDENCE ARE EXPECTED TO HAVE
LEFT THE ATMOSPHERE RELATIVELY STABLE BY LATE TONIGHT.
HOWEVER...THE GFS/NAM/ECMWF ALL SHOW RELATIVELY STRONG AND
PERSISTENT ISENTROPIC LIFT ON THE 305 K SURFACE IN BETWEEN 06 AND
12Z MONDAY MORNING OVER THE FAR SOUTHEASTERN COUNTIES OF THE CWA.
MODELS DO NOT SHOW MUCH IN THE WAY OF QPF...HOWEVER MID-LEVEL
MOISTURE WILL LIKELY RESIDE NEAR THE GULF COAST BEFORE THIS TROUGH
MOVES OVER THE REGION TONIGHT. IT SEEMS REASONABLE THAT SOME OF
THIS MOISTURE WILL RETURN ON THE 305K SURFACE (NEAR THE H700 LEVEL
TONIGHT) AND RESULT IN SOME PERSISTENT MID-LEVEL PRECIPITATION
PRODUCTION BEFORE SUNRISE MONDAY.
THE LOWER TROPOSPHERE IS EXPECTED TO BE QUITE DRY BEFORE THIS
PROCESS STARTS...SO A SIGNIFICANT AMOUNT OF THIS MID-LEVEL
PRECIPITATION IS LIKELY TO EVAPORATE BEFORE REACHING THE GROUND.
REGARDLESS...CONFIDENCE IN THE MID-LEVEL PRECIPITATION PRODUCTION
IS HIGH...SO WENT AHEAD AND MENTIONED A 20 PERCENT CHANCE OF RAIN
OR FREEZING RAIN SOUTHEAST OF AN ATHENS TO TEMPLE LINE (NOT
INCLUDING WACO AT THIS TIME) FOR EARLY MONDAY MORNING. DO NOT
THINK THE IMPACTS OF THIS WILL BE HIGH UNLESS THE LOWER ATMOSPHERE
SATURATES QUICKER THAN EXPECTED. LIGHT PRECIPITATION WILL LIKELY
CONTINUE AFTER SUNRISE MONDAY MORNING FOR THESE
LOCATIONS...HOWEVER TEMPERATURES ARE LIKELY TO WARM ABOVE FREEZING
AFTER SUNRISE. WE MAY HAVE TO CONSIDER A WINTER WEATHER OR
FREEZING RAIN ADVISORY IF IT LOOKS LIKE MORE PRECIPITATION WILL
MAKE IT TO THE GROUND...BUT CONFIDENCE IS TOO LOW TO GO WITH
ANYTHING AT THIS TIME.
FOR MID-WEEK...THE ECMWF HAS COME MORE IN LINE WITH THE NAEFS
SOLUTION INDICATING THAT THE LONGWAVE TROUGH OVER THE WESTERN
THIRD OF THE CONUS WILL CONSOLIDATE AND MOVE EAST AS A POSITIVELY
TILTED TROUGH TUESDAY NIGHT INTO WEDNESDAY. THIS SOLUTION LIMITS
LARGE SCALE FORCING FOR ASCENT OVER NORTH AND CENTRAL TX BY
KEEPING LOW LEVEL FLOW VEERED AS IT MOVES OVER THE AREA. THIS
WOULD ALSO PREVENT ANY SIGNIFICANT MOISTURE FROM RETURNING TO THE
REGION OUT AHEAD OF THIS UPPER TROUGH. THE 00 AND 06Z NAM
SOLUTIONS BOTH PREFER THE STRONG AND SLOW MOVING CUT-OFF LOW
SOLUTION ADVERTISED BY THE ECMWF THE PAST FEW DAYS. WHILE THIS
SOLUTION IS AN OUTLIER SOLUTION...WE WILL CONTINUE TO WATCH FOR
ANY SIGN THAT THIS SOLUTION COULD VERIFY AS IT WOULD LIKELY ALLOW
FOR A SIGNIFICANT ICE STORM IN THE REGION IF IT VERIFIED. THIS
FORECAST CONTINUES TO SIDE WITH THE CONSENSUS OF THE NAEFS AND THE
13/00Z ECMWF AS THIS IS BY FAR THE MOST LIKELY OUTCOME. HOWEVER
WILL NOT COMPLETELY IGNORE THE NAM AS IT WOULD BRING A HIGH IMPACT
WINTER WEATHER EVENT TO SOME PART OF NORTH OR CENTRAL TX.
EXTENDED...ONCE THE LONGER WAVE TROUGH MOVES OUT OF THE
REGION...WE SHOULD SEE A SLOW WARMING TREND FOR THE REGION AS A
BLOCKING RIDGE SETS UP OVER THE WESTERN CONUS COAST KEEPING MORE
OR LESS NORTHWEST AND CONFLUENT FLOW OVER THE SOUTH PLAINS. THIS
WARM UP COULD COME TO AN ABRUPT END EARLY NEXT WEEK AS BOTH THE
GFS AND THE ECMWF HAVE A STRONG COLD FRONT MOVING SOUTH THROUGH
THE GREAT PLAINS. THE GFS COOLS US DOWN...BUT ALLOWS THE COLD AIR
TO MODIFY TO THE POINT THAT IT BEHAVES LIKE A TYPICAL WINTER COLD
FRONT FOR TEXAS. THAT IS WE COOL DOWN SIGNIFICANTLY...BUT
OVERNIGHT LOWS TEND TO SAY IN THE MID TO UPPER 20S WHILE HIGHS
CLIMB ABOVE FREEZING.
THE ECMWF BRINGS A SIGNIFICANT ARCTIC OUTBREAK SOUTH THROUGH THE
PLAINS...WHICH WOULD IMPACT NORTH TX SUNDAY NIGHT OR MONDAY IF IT
VERIFIED. THE 13/00Z ECMWF HAS A 1053 MB (MSLP) SURFACE HIGH
BARRELING SOUTH INTO THE CENTRAL PLAINS BEHIND THIS FRONT...WHICH
IS A SIGN OF A VERY COLD ARCTIC AIR INVASION OF THE PLAINS. THIS
IS NOT THE MOST LIKELY SOLUTION TO VERIFY AT THIS TIME...BUT IT
BEARS WATCHING AS WE GET CLOSER TO NEXT WEEKEND AND EARLY NEXT
WEEK. THE ECMWF WOULD BRING LOWS DOWN INTO THE TEENS IF NOT LOWER
ACROSS NORTH TX WHICH COULD CERTAINLY HAVE A BIG IMPACT ON THE
REGION. THIS IS SLIGHTLY BEYOND THE OFFICIAL FORECAST PERIOD AT
THIS TIME...SO WILL WATCH FOR MORE CONSISTENCY AMONGST MODELS
BEFORE JUMPING ON AN ARCTIC OUTBREAK TO START OFF THE NEXT WORK
WEEK.
CAVANAUGH
&&
.PRELIMINARY POINT TEMPS/POPS...
DALLAS-FT. WORTH, TX 42 26 44 28 45 / 10 10 5 10 10
WACO, TX 45 27 43 27 45 / 10 10 10 10 10
PARIS, TX 41 25 44 26 43 / 30 10 10 10 10
DENTON, TX 42 24 43 23 45 / 10 10 5 10 10
MCKINNEY, TX 42 24 44 24 43 / 30 10 10 10 10
DALLAS, TX 42 27 44 29 44 / 10 10 10 10 10
TERRELL, TX 44 26 43 27 43 / 20 10 10 10 10
CORSICANA, TX 44 28 44 30 43 / 10 10 10 10 10
TEMPLE, TX 46 27 43 27 44 / 10 10 10 10 10
MINERAL WELLS, TX 42 22 43 22 44 / 5 10 5 5 10
&&
.FWD WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
85/85
AREA FORECAST DISCUSSION
NWS LUBBOCK TX
835 AM CST SUN JAN 13 2013
.UPDATE...
LATEST RADAR TRENDS SHOWED CLEARING SKIES AND THUS NO NEED FOR A
-SN MENTION ACROSS THE NORTHEASTERN SOUTH PLAINS. HAVE THEREFORE
UPDATED THE FORECAST TO REFLECT THIS CHANGE.
&&
.PREV DISCUSSION... /ISSUED 556 AM CST SUN JAN 13 2013/
AVIATION...
MVFR CIGS IN PLACE AT KLBB ARE EXPECTED TO SCATTER OUT BY MID-
MORNING...THOUGH THERE IS A LOW CHANCE THEY COULD HANG IN PLACE
INTO THE AFTERNOON. KCDS IS CURRENTLY EXPERIENCING VFR CIGS AND
THINK THIS IS WHERE THEY WILL STAY. HOWEVER...A WEAKENING BAND OF
SNOW APPROACHING KCDS FROM THE WEST COULD BRIEFLY CAUSE CIGS TO
LOWER TO NEAR MVFR LEVELS...PERHAPS EVEN SUPPLYING A FEW FLURRIES
OR LIGHT SNOW SHOWERS...THOUGH NO IMPACTS ARE EXPECTED.
OTHERWISE...HAVE VFR CONDITIONS IN PLACE AT THE TERMINALS THIS
AFTERNOON AND TONIGHT WITH NORTHERLY WINDS THIS MORNING VEERING TO
EASTERLY BY MIDDAY AT KLBB AND BY THIS EVENING AT KCDS. THE
UPSLOPE FLOW RAISES SOME CONCERN THAT LOW CLOUDS COULD
REDEVELOP TONIGHT...THOUGH CURRENT GUIDANCE ARGUES AGAINST THIS
WITH RELATIVELY DRY AIR IN PLACE.
PREV DISCUSSION... /ISSUED 354 AM CST SUN JAN 13 2013/
SHORT TERM...
A SPRAWLING AND COMPLEX UPPER LEVEL TROUGH WAS DOMINATING THE
WESTERN 2/3RDS OF THE CONUS...WITH SEVERAL EMBEDDED DISTURBANCES
NOTED WITHIN IT. ONE SUCH SHORTWAVE TROUGH WAS GRAZING THE AREA
EARLY THIS MORNING...WITH ANOTHER CURRENTLY DIVING DOWN THE SOUTHERN
CALIFORNIA COAST PROGGED TO APPROACH FROM THE WEST LATE TONIGHT. THE
FORMER HAS PROVIDED STRONG ENOUGH LIFT TO PRODUCE A BAND OF SNOW
THAT HAS TRAVERSED THE NORTHWEST AND NORTH-CENTRAL ZONES EARLY THIS
MORNING. EVEN THOUGH THE PRESENTATION ON RADAR WITHIN THIS BAND HAS
NOT BEEN OVERLY IMPRESSIVE AND MOISTURE IS RATHER LIMITED...THE BAND
HAS BEEN ABLE TO SQUEEZE OUT EFFICIENT SNOW RATES GIVEN THE COLD
TEMPERATURES AND HIGH SNOW TO LIQUID RATIOS. FRIONA REPORTED A QUICK
1-2 INCHES OF SNOW AS THE BAND MOVED THROUGH EARLIER THIS
MORNING...WITH DIMMITT AND TULIA REPORTING LESS THAN 1 INCH. LIFT
SUPPORTING THIS BAND WILL GRADUALLY WANE MOVING TOWARDS
DAYBREAK...BUT A LITTLE LIGHT SNOW OR FLURRIES COULD LINGER PAST 12Z
ACROSS THE NORTHEAST ZONES.
OTHERWISE...COLD SFC RIDGING WILL DOMINATE THE REGION THROUGH THE
SHORT TERM. LOW STRATUS CLOUDS HAVE DEVELOPED ACROSS ROUGHLY THE
NORTHWEST HALF OF THE CWA IN THIS REGIME EARLY THIS MORNING. BOTH
THE NAM AND GFS SUGGEST THESE CLOUDS WILL QUICKLY SCATTER OUT THIS
MORNING AS MID- AND UPPER-LEVEL SUBSIDENCE INCREASES IN THE WAKE OF
THE PASSING SHORTWAVE TROUGH. ON THE OTHER HAND...THE RUC AND HRRR
SUGGEST THAT THE LOW CLOUDS MAY HANG ON MUCH OR ALL OF THE DAY ON
THE CAPROCK AS WINDS VEER EASTERLY AND THE SHALLOW BUT RELATIVELY
MOIST UPSLOPE FLOW ENSUES. CURRENT FORECAST IN THE GRIDS DOES
INDICATE CLEARING SKIES BY MIDDAY...BUT IF THIS DOES NOT
OCCUR...FORECAST HIGHS WILL LIKELY BE TOO HIGH. REGARDLESS...IT WILL
BE A CHILLY DAY AND HAVE FAVORED THE LOW SIDE OF MOS GUIDANCE WITH
FORECAST HIGHS IN THE LOWER TO MIDDLE 30S FOR ALL BUT THE NORTHWEST
ZONES WHERE UPPER 20S WERE CARRIED.
CHILLY EASTERLY UPSLOPE FLOW WILL CONTINUE THROUGH TONIGHT. PROGGED
SOUNDINGS INDICATE MOSTLY CLEAR SKIES EARLY ON...WITH SOME MID-LEVEL
CLOUDS VISITING AT LEAST THE NORTHWEST ZONES LATE AS THE NEXT
SHORTWAVE TROUGH RACES BY. HOWEVER...GIVEN THE UPSLOPE FLOW WOULD
NOT BE SURPRISED IF SOME LOWER CLOUDS DEVELOP OR PERSIST. ALTHOUGH
MODELS ARE GENERALLY DRY...THINK THERE MAY BE ENOUGH LIFT AND
MOISTURE TO SQUEEZE OUT A FEW FLURRIES ACROSS THE WESTERN ZONES LATE
TONIGHT AND HAVE INSERTED THIS INTO THE FORECAST. EXTENT AND
DURATION OF ANY CLOUD COVER COULD HAVE SOME IMPACTS ON EXACTLY HOW
COLD IT GETS TONIGHT...BUT EITHER WAY IT WILL BE CHILLY AND HAVE
MAINTAINED LOWS 10-15 DEGREES BELOW MID-JANUARY AVERAGES /RANGING
FROM 9 DEGREES NORTHWEST TO MID-TEENS OUT EAST/.
LONG TERM...
THE MON THRU THU FORECAST HINGES ON THE STRENGTH AND TRACK OF THE
SRN PORTION OF THE UPPER-LEVEL TROUGH...INITIALLY LOCATED OVER AZ
AND NM MONDAY MORNING. THE MAJORITY OF GUIDANCE ELONGATES THE TROUGH
FROM THE SW TO NE AS IT SLIDES SEWD ACROSS WEST TEXAS...WITH
MOISTURE AND LIFT BOTH LACKING TO WRING OUT ANY PRECIPITATION FOR
OUR AREA...BEFORE IT EVENTUALLY CLOSES OFF AT 500 MB ACROSS NORTH
CENTRAL TX. HOWEVER...THERE ARE STILL A FEW MODELS /E.G. 0Z NAM
AND CMC/ AND SOME GEFS ENSEMBLE MEMBERS THAT CLOSED OFF TROUGH
INTO A CUTOFF LOW ACROSS SRN NM OR NRN MX...THEN TRACK IT SLOWLY
EAST ACROSS WEST TEXAS MID-WEEK. IN THE LATTER CASE COULD BRING
A CHANCE OF SOME RAIN OR SNOW IN THE TUE THRU THU TIME FRAME AS
BOTH MOISTURE ADVECTION AND LIFT WOULD BE ENHANCED. BUT
PREPONDERANCE OF GUIDANCE SUGGESTS THE OPEN WAVE PASSAGE
ACCOMPANIED BY ONLY AN INCREASE IN MID-LVL CLOUD COVER. THUS WE/VE
KEPT POPS BELOW MENTION THROUGH THE EXTENDED PERIOD...ALTHOUGH
NUDGED THEM UP TO 10 PERCENT ACROSS OUR SRN ZONES. MONDAY STILL
APPEARS TO BE THE COOLEST DAY IN THE PERIOD...WITH HIGHS ONLY IN
THE LOW TO MID 30S. TUESDAY WILL ONLY BE SLIGHTLY WARMER...WITH
HIGHS IN THE UPPER 30S TO LOW 40S. FINALLY...BARRING THE CLOSED
LOW SOLUTION...HIGHS WILL WARM BACK INTO THE UPPER 40S AND 50S WED
AND THU.
FRI-SAT: AFTER THE TROUGH/LOW PASSES...WEAK ZONAL TO SW FLOW SHOULD
EXTEND OVER THE AREA AS A BROAD LOW-AMPLITUDE TROUGH DEVELOPS OVER
THE DESERT SOUTHWEST. SOME SUB-TROPICAL MOISTURE MAY GET DRAWN UP BY
THE TROUGH TO BRING SOME HIGH CLOUD COVER TO THE AREA BY FRIDAY. AND
JUST TO OUR NORTH...UPPER FLOW WILL BECOME CYCLONIC AS A DEEP
TROUGH DROPS INTO THE GREAT LAKES REGION...WHILE THE UPPER RIDGE
RE-AMPLIFIES ALONG THE PACIFIC COAST. TEMPS WILL CONTINUE TO BE
MILD WITH HIGHS MAINLY IN THE MID TO UPPER 50S.
A WEAK FRONT IS EXPECTED TO MOVE INTO THE AREA BY SUNDAY...RESULTING IN
A MODEST COOL DOWN DEPENDING ON THE TIMING OF THE FROPA. A MUCH
STRONGER FRONT IS POSSIBLE BY MONDAY THE 21ST...AS A 1050MB SFC RIDGE
DIVES OUT OF CENTRAL CANADA INTO THE PLAINS. IT IS STILL TOO EARLY
TO TELL IF THIS COLD AIR MASS WILL SETTLE INTO WEST TEXAS OR IF
WE/LL ONLY RECEIVE A GLANCING BLOW.
&&
.PRELIMINARY POINT TEMPS/POPS...
FRIONA 28 9 29 9 37 / 10 10 10 10 10
TULIA 29 10 30 12 38 / 0 0 10 10 10
PLAINVIEW 31 11 31 11 38 / 10 10 10 10 10
LEVELLAND 34 11 32 12 38 / 10 10 10 10 10
LUBBOCK 33 12 33 13 39 / 10 10 0 10 10
DENVER CITY 36 13 32 12 38 / 10 10 10 10 10
BROWNFIELD 36 12 32 13 38 / 10 10 0 10 10
CHILDRESS 35 15 34 15 41 / 0 0 0 0 10
SPUR 35 14 34 15 40 / 0 0 0 0 10
ASPERMONT 37 16 36 14 41 / 0 0 10 0 10
&&
.LUB WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
29
AREA FORECAST DISCUSSION...UPDATED
NWS FORT WORTH TX
519 AM CST SUN JAN 13 2013
.AVIATION...
/12Z TAFS/
VFR CONDITIONS GENERALLY PREVAIL ACROSS NORTH TEXAS AS LOW LEVELS
CONTINUE TO DRY OUT. BKN/OVC CONDS WITH CIGS AROUND 8000FT ARE
EXPECTED TO PERSIST FOR THE NEXT SEVERAL HOURS. FORCING FROM
STRONG TROUGH TO THE WEST AND AVAILABLE MID LEVEL MOISTURE ARE
RESULTING IN CONTINUED SCATTERED ELEVATED CONVECTION GENERALLY
EAST OF THE MAJOR AIRPORTS. SMALL HAIL AND A FEW LIGHTNING STRIKES
WILL ACCOMPANY THIS ACTIVITY THROUGH MID MORNING. OTHERWISE...THE
STRONG NORTH WINDS WILL PERSIST THROUGHOUT THE DAY BEFORE
DIMINISHING TONIGHT. VFR CONDITIONS EXPECTED TO PREVAIL ON MONDAY.
DUNN
&&
.PREV DISCUSSION... /ISSUED 425 AM CST SUN JAN 13 2013/
SHORT TERM WINTER WEATHER/FORECAST CONCERNS...
DID NOT MAKE ANY SIGNIFICANT CHANGES TO THE FORECAST FROM THE 139
AM CST FORECAST UPDATE/AFD. THERE IS STILL NO MODEL GUIDANCE THAT
HAS A GOOD HANDLE ON WINTRY PRECIPITATION FALLING NORTHWEST OF THE
METROPLEX EARLY THIS MORNING. THE HRRR IS CLOSEST...BUT DOESNT
SEEM TO KNOW WHAT IS CAUSING THE WINTRY PRECIPITATION. THE HRRR
CONSISTENTLY INITIALIZES THE RADAR RETURNS AND THEN ALLOWS THEM TO
DISSIPATE SHORTLY THEREAFTER WHICH IS A GOOD SIGN THAT THE MODEL
IS NOT RESOLVING THE FORCING MECHANISM THAT IS RESPONSIBLE FOR THE
PRESENCE OF THE PRECIPITATION. AT ANY RATE...DRAWING BACK ON
MORNING UPDATE DISCUSSIONS...THE GFS FORECAST THAT H700 CONFLUENCE
WOULD DISSIPATE EARLY THIS MORNING SEEMS TO BE SPOT ON ACCORDING
TO REGIONAL VWP OUTPUT. THE BEST H700 CONFLUENCE HAD MOVED NORTH
OF THE RED RIVER AS OF 09Z...AND LIGHT WINTRY PRECIPITATION WAS
LIFTING NORTHEAST AS WELL. THERE IS STILL SOME CONCERN FOR H800
FRONTOGENETIC FORCING ALONG A SHERMAN TO FORT WORTH TO GRANBURY
LINE AROUND SUNRISE RESULTING IN SOME SHALLOW CONVECTION
INITIATION. THE GFS CONTINUES TO ADVERTISE THIS FORCING FOR
ASCENT NEAR THE H800 LEVEL WITH A 100 MB LAYER ABOVE IT
CHARACTERIZED BY DECREASING THETA-E TEMPERATURES WITH
HEIGHT (ESSENTIALLY POSITIVE CAPE).
THAT SAID...THERE IS NO OBSERVATIONAL EVIDENCE THAT STRONG LIFT IS
OCCURRING AT THIS TIME AS THERE ARE NO RAPIDLY COOLING CLOUD TOPS
OR LIGHT MID-LEVEL RADAR REFLECTIVITY RETURNS OVER THESE AREAS AT
THE TIME OF THIS DISCUSSION. THEREFORE WILL NOT BE ISSUING A
FREEZING RAIN ADVISORY FROM SHERMAN...THROUGH THE DFW METROPLEX
AND SOUTHWEST TOWARDS GRANBURY AT THIS TIME. OF COURSE WE WILL
CONTINUE TO MONITOR THIS SITUATION CLOSELY THROUGH SUNRISE AS ANY
DEVELOPING PRECIPITATION WILL LIKELY BE COMPOSED OF SUPERCOOLED
WATER. WHILE THIS WOULD FALL IN LIQUID FORM...IT WOULD FREEZE
IMMEDIATELY UPON CONTACT WITH ANY SURFACE THAT IS ALSO AT OR BELOW
FREEZING. AT THIS TIME IT LOOKS AS THOUGH MOST PRECIPITATION
DEVELOPMENT WILL REMAIN SOUTHEAST OF THIS LINE THROUGH
SUNRISE...DIMINISHING THE THREAT FOR FREEZING RAIN OR SLEET.
TODAY THROUGH MONDAY...ALL GUIDANCE INDICATES THAT LOW-LEVEL
FRONTOGENETIC FORCING WILL DIMINISH IN INTENSITY THIS MORNING AS
DRY AIR AND SUBSIDENCE CONTINUE TO SLOWLY WORK INTO THE REGION.
DRY AIR NEAR THE SURFACE HAS ALREADY PENETRATED AS FAR SOUTHEAST
AS AN ATHENS TO TEMPLE LINE...BUT IT IS THE MOISTURE ALOFT THAT WE
HAVE TO WORRY ABOUT EARLY THIS MORNING. EXPECT ALL LIGHT RAIN/RAIN
SHOWERS TO MOVE EAST AFTER 18Z. DID KEEP IN A 20 PERCENT CHANCE
FOR A RAIN/SLEET MIX FOR LOCATIONS ALONG AND NORTH OF A
GAINESVILLE TO MCKINNEY TO COOPER LINE AFTER SUNRISE JUST IN CASE
THE H800 FRONTOGENESIS SCENARIO DESCRIBED ABOVE PANS OUT. THESE
LOCATIONS WOULD ALSO HAVE TO BE INCLUDED IN A BRIEF FREEZING RAIN
ADVISORY IF THIS PRECIPITATION DOES MANAGE TO DEVELOP AROUND/JUST
BEFORE SUNRISE. IF IT DOES NOT...THESE AREAS WILL LIKELY REMAIN
DRY THIS MORNING.
WE SHOULD SEE SOME SUNSHINE BY LATE THIS AFTERNOON...HOWEVER NOT
MUCH OF A WARM-UP IS EXPECTED TODAY AS NORTH WINDS AND MORNING
CLOUD COVER HELP TO KEEP TEMPERATURES IN THE LOWER TO MID 40S FOR
HIGHS FOR MOST LOCATIONS. FOR TONIGHT...ANOTHER STRONG SHORTWAVE
TROUGH IS EXPECTED TO MOVE OVER THE SOUTH PLAINS. THIS TROUGH WAS
OVER THE SOUTHERN CA COAST PER EARLY MORNING WATER VAPOR IMAGERY.
THIS TROUGH HAS A WELL-DEFINED CYCLONIC CIRCULATION IN WATER VAPOR
IMAGERY AND IS PROGGED TO SEND STRONG LARGE SCALE FORCING FOR
ASCENT OVER THE REGION AS IT MOVES NORTHEAST TONIGHT AND INTO
MONDAY MORNING.
FOR MOST OF NORTH TX...THIS STRONG FORCING FOR ASCENT IS EXPECTED
TO GO UNNOTICED AS DRY AIR AND SUBSIDENCE ARE EXPECTED TO HAVE
LEFT THE ATMOSPHERE RELATIVELY STABLE BY LATE TONIGHT.
HOWEVER...THE GFS/NAM/ECMWF ALL SHOW RELATIVELY STRONG AND
PERSISTENT ISENTROPIC LIFT ON THE 305 K SURFACE IN BETWEEN 06 AND
12Z MONDAY MORNING OVER THE FAR SOUTHEASTERN COUNTIES OF THE CWA.
MODELS DO NOT SHOW MUCH IN THE WAY OF QPF...HOWEVER MID-LEVEL
MOISTURE WILL LIKELY RESIDE NEAR THE GULF COAST BEFORE THIS TROUGH
MOVES OVER THE REGION TONIGHT. IT SEEMS REASONABLE THAT SOME OF
THIS MOISTURE WILL RETURN ON THE 305K SURFACE (NEAR THE H700 LEVEL
TONIGHT) AND RESULT IN SOME PERSISTENT MID-LEVEL PRECIPITATION
PRODUCTION BEFORE SUNRISE MONDAY.
THE LOWER TROPOSPHERE IS EXPECTED TO BE QUITE DRY BEFORE THIS
PROCESS STARTS...SO A SIGNIFICANT AMOUNT OF THIS MID-LEVEL
PRECIPITATION IS LIKELY TO EVAPORATE BEFORE REACHING THE GROUND.
REGARDLESS...CONFIDENCE IN THE MID-LEVEL PRECIPITATION PRODUCTION
IS HIGH...SO WENT AHEAD AND MENTIONED A 20 PERCENT CHANCE OF RAIN
OR FREEZING RAIN SOUTHEAST OF AN ATHENS TO TEMPLE LINE (NOT
INCLUDING WACO AT THIS TIME) FOR EARLY MONDAY MORNING. DO NOT
THINK THE IMPACTS OF THIS WILL BE HIGH UNLESS THE LOWER ATMOSPHERE
SATURATES QUICKER THAN EXPECTED. LIGHT PRECIPITATION WILL LIKELY
CONTINUE AFTER SUNRISE MONDAY MORNING FOR THESE
LOCATIONS...HOWEVER TEMPERATURES ARE LIKELY TO WARM ABOVE FREEZING
AFTER SUNRISE. WE MAY HAVE TO CONSIDER A WINTER WEATHER OR
FREEZING RAIN ADVISORY IF IT LOOKS LIKE MORE PRECIPITATION WILL
MAKE IT TO THE GROUND...BUT CONFIDENCE IS TOO LOW TO GO WITH
ANYTHING AT THIS TIME.
FOR MID-WEEK...THE ECMWF HAS COME MORE IN LINE WITH THE NAEFS
SOLUTION INDICATING THAT THE LONGWAVE TROUGH OVER THE WESTERN
THIRD OF THE CONUS WILL CONSOLIDATE AND MOVE EAST AS A POSITIVELY
TILTED TROUGH TUESDAY NIGHT INTO WEDNESDAY. THIS SOLUTION LIMITS
LARGE SCALE FORCING FOR ASCENT OVER NORTH AND CENTRAL TX BY
KEEPING LOW LEVEL FLOW VEERED AS IT MOVES OVER THE AREA. THIS
WOULD ALSO PREVENT ANY SIGNIFICANT MOISTURE FROM RETURNING TO THE
REGION OUT AHEAD OF THIS UPPER TROUGH. THE 00 AND 06Z NAM
SOLUTIONS BOTH PREFER THE STRONG AND SLOW MOVING CUT-OFF LOW
SOLUTION ADVERTISED BY THE ECMWF THE PAST FEW DAYS. WHILE THIS
SOLUTION IS AN OUTLIER SOLUTION...WE WILL CONTINUE TO WATCH FOR
ANY SIGN THAT THIS SOLUTION COULD VERIFY AS IT WOULD LIKELY ALLOW
FOR A SIGNIFICANT ICE STORM IN THE REGION IF IT VERIFIED. THIS
FORECAST CONTINUES TO SIDE WITH THE CONSENSUS OF THE NAEFS AND THE
13/00Z ECMWF AS THIS IS BY FAR THE MOST LIKELY OUTCOME. HOWEVER
WILL NOT COMPLETELY IGNORE THE NAM AS IT WOULD BRING A HIGH IMPACT
WINTER WEATHER EVENT TO SOME PART OF NORTH OR CENTRAL TX.
EXTENDED...ONCE THE LONGER WAVE TROUGH MOVES OUT OF THE
REGION...WE SHOULD SEE A SLOW WARMING TREND FOR THE REGION AS A
BLOCKING RIDGE SETS UP OVER THE WESTERN CONUS COAST KEEPING MORE
OR LESS NORTHWEST AND CONFLUENT FLOW OVER THE SOUTH PLAINS. THIS
WARM UP COULD COME TO AN ABRUPT END EARLY NEXT WEEK AS BOTH THE
GFS AND THE ECMWF HAVE A STRONG COLD FRONT MOVING SOUTH THROUGH
THE GREAT PLAINS. THE GFS COOLS US DOWN...BUT ALLOWS THE COLD AIR
TO MODIFY TO THE POINT THAT IT BEHAVES LIKE A TYPICAL WINTER COLD
FRONT FOR TEXAS. THAT IS WE COOL DOWN SIGNIFICANTLY...BUT
OVERNIGHT LOWS TEND TO SAY IN THE MID TO UPPER 20S WHILE HIGHS
CLIMB ABOVE FREEZING.
THE ECMWF BRINGS A SIGNIFICANT ARCTIC OUTBREAK SOUTH THROUGH THE
PLAINS...WHICH WOULD IMPACT NORTH TX SUNDAY NIGHT OR MONDAY IF IT
VERIFIED. THE 13/00Z ECMWF HAS A 1053 MB (MSLP) SURFACE HIGH
BARRELING SOUTH INTO THE CENTRAL PLAINS BEHIND THIS FRONT...WHICH
IS A SIGN OF A VERY COLD ARCTIC AIR INVASION OF THE PLAINS. THIS
IS NOT THE MOST LIKELY SOLUTION TO VERIFY AT THIS TIME...BUT IT
BEARS WATCHING AS WE GET CLOSER TO NEXT WEEKEND AND EARLY NEXT
WEEK. THE ECMWF WOULD BRING LOWS DOWN INTO THE TEENS IF NOT LOWER
ACROSS NORTH TX WHICH COULD CERTAINLY HAVE A BIG IMPACT ON THE
REGION. THIS IS SLIGHTLY BEYOND THE OFFICIAL FORECAST PERIOD AT
THIS TIME...SO WILL WATCH FOR MORE CONSISTENCY AMONGST MODELS
BEFORE JUMPING ON AN ARCTIC OUTBREAK TO START OFF THE NEXT WORK
WEEK.
CAVANAUGH
&&
.PRELIMINARY POINT TEMPS/POPS...
DALLAS-FT. WORTH, TX 42 26 44 28 45 / 10 10 5 10 10
WACO, TX 45 27 43 27 45 / 10 10 10 10 10
PARIS, TX 41 25 44 26 43 / 20 10 10 10 10
DENTON, TX 42 24 43 23 45 / 10 10 5 10 10
MCKINNEY, TX 42 24 44 24 43 / 20 10 10 10 10
DALLAS, TX 42 27 44 29 44 / 10 10 10 10 10
TERRELL, TX 44 26 43 27 43 / 10 10 10 10 10
CORSICANA, TX 44 28 44 30 43 / 10 10 10 10 10
TEMPLE, TX 46 27 43 27 44 / 10 10 10 10 10
MINERAL WELLS, TX 42 22 43 22 44 / 5 10 5 5 10
&&
.FWD WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS FORT WORTH TX
425 AM CST SUN JAN 13 2013
.DISCUSSION...
SHORT TERM WINTER WEATHER/FORECAST CONCERNS...
DID NOT MAKE ANY SIGNIFICANT CHANGES TO THE FORECAST FROM THE 139
AM CST FORECAST UPDATE/AFD. THERE IS STILL NO MODEL GUIDANCE THAT
HAS A GOOD HANDLE ON WINTRY PRECIPITATION FALLING NORTHWEST OF THE
METROPLEX EARLY THIS MORNING. THE HRRR IS CLOSEST...BUT DOESNT
SEEM TO KNOW WHAT IS CAUSING THE WINTRY PRECIPITATION. THE HRRR
CONSISTENTLY INITIALIZES THE RADAR RETURNS AND THEN ALLOWS THEM TO
DISSIPATE SHORTLY THEREAFTER WHICH IS A GOOD SIGN THAT THE MODEL
IS NOT RESOLVING THE FORCING MECHANISM THAT IS RESPONSIBLE FOR THE
PRESENCE OF THE PRECIPITATION. AT ANY RATE...DRAWING BACK ON
MORNING UPDATE DISCUSSIONS...THE GFS FORECAST THAT H700 CONFLUENCE
WOULD DISSIPATE EARLY THIS MORNING SEEMS TO BE SPOT ON ACCORDING
TO REGIONAL VWP OUTPUT. THE BEST H700 CONFLUENCE HAD MOVED NORTH
OF THE RED RIVER AS OF 09Z...AND LIGHT WINTRY PRECIPITATION WAS
LIFTING NORTHEAST AS WELL. THERE IS STILL SOME CONCERN FOR H800
FRONTOGENETIC FORCING ALONG A SHERMAN TO FORT WORTH TO GRANBURY
LINE AROUND SUNRISE RESULTING IN SOME SHALLOW CONVECTION
INITIATION. THE GFS CONTINUES TO ADVERTISE THIS FORCING FOR
ASCENT NEAR THE H800 LEVEL WITH A 100 MB LAYER ABOVE IT
CHARACTERIZED BY DECREASING THETA-E TEMPERATURES WITH
HEIGHT (ESSENTIALLY POSITIVE CAPE).
THAT SAID...THERE IS NO OBSERVATIONAL EVIDENCE THAT STRONG LIFT IS
OCCURRING AT THIS TIME AS THERE ARE NO RAPIDLY COOLING CLOUD TOPS
OR LIGHT MID-LEVEL RADAR REFLECTIVITY RETURNS OVER THESE AREAS AT
THE TIME OF THIS DISCUSSION. THEREFORE WILL NOT BE ISSUING A
FREEZING RAIN ADVISORY FROM SHERMAN...THROUGH THE DFW METROPLEX
AND SOUTHWEST TOWARDS GRANBURY AT THIS TIME. OF COURSE WE WILL
CONTINUE TO MONITOR THIS SITUATION CLOSELY THROUGH SUNRISE AS ANY
DEVELOPING PRECIPITATION WILL LIKELY BE COMPOSED OF SUPERCOOLED
WATER. WHILE THIS WOULD FALL IN LIQUID FORM...IT WOULD FREEZE
IMMEDIATELY UPON CONTACT WITH ANY SURFACE THAT IS ALSO AT OR BELOW
FREEZING. AT THIS TIME IT LOOKS AS THOUGH MOST PRECIPITATION
DEVELOPMENT WILL REMAIN SOUTHEAST OF THIS LINE THROUGH
SUNRISE...DIMINISHING THE THREAT FOR FREEZING RAIN OR SLEET.
TODAY THROUGH MONDAY...ALL GUIDANCE INDICATES THAT LOW-LEVEL
FRONTOGENETIC FORCING WILL DIMINISH IN INTENSITY THIS MORNING AS
DRY AIR AND SUBSIDENCE CONTINUE TO SLOWLY WORK INTO THE REGION.
DRY AIR NEAR THE SURFACE HAS ALREADY PENETRATED AS FAR SOUTHEAST
AS AN ATHENS TO TEMPLE LINE...BUT IT IS THE MOISTURE ALOFT THAT WE
HAVE TO WORRY ABOUT EARLY THIS MORNING. EXPECT ALL LIGHT RAIN/RAIN
SHOWERS TO MOVE EAST AFTER 18Z. DID KEEP IN A 20 PERCENT CHANCE
FOR A RAIN/SLEET MIX FOR LOCATIONS ALONG AND NORTH OF A
GAINESVILLE TO MCKINNEY TO COOPER LINE AFTER SUNRISE JUST IN CASE
THE H800 FRONTOGENESIS SCENARIO DESCRIBED ABOVE PANS OUT. THESE
LOCATIONS WOULD ALSO HAVE TO BE INCLUDED IN A BRIEF FREEZING RAIN
ADVISORY IF THIS PRECIPITATION DOES MANAGE TO DEVELOP AROUND/JUST
BEFORE SUNRISE. IF IT DOES NOT...THESE AREAS WILL LIKELY REMAIN
DRY THIS MORNING.
WE SHOULD SEE SOME SUNSHINE BY LATE THIS AFTERNOON...HOWEVER NOT
MUCH OF A WARM-UP IS EXPECTED TODAY AS NORTH WINDS AND MORNING
CLOUD COVER HELP TO KEEP TEMPERATURES IN THE LOWER TO MID 40S FOR
HIGHS FOR MOST LOCATIONS. FOR TONIGHT...ANOTHER STRONG SHORTWAVE
TROUGH IS EXPECTED TO MOVE OVER THE SOUTH PLAINS. THIS TROUGH WAS
OVER THE SOUTHERN CA COAST PER EARLY MORNING WATER VAPOR IMAGERY.
THIS TROUGH HAS A WELL-DEFINED CYCLONIC CIRCULATION IN WATER VAPOR
IMAGERY AND IS PROGGED TO SEND STRONG LARGE SCALE FORCING FOR
ASCENT OVER THE REGION AS IT MOVES NORTHEAST TONIGHT AND INTO
MONDAY MORNING.
FOR MOST OF NORTH TX...THIS STRONG FORCING FOR ASCENT IS EXPECTED
TO GO UNNOTICED AS DRY AIR AND SUBSIDENCE ARE EXPECTED TO HAVE
LEFT THE ATMOSPHERE RELATIVELY STABLE BY LATE TONIGHT.
HOWEVER...THE GFS/NAM/ECMWF ALL SHOW RELATIVELY STRONG AND
PERSISTENT ISENTROPIC LIFT ON THE 305 K SURFACE IN BETWEEN 06 AND
12Z MONDAY MORNING OVER THE FAR SOUTHEASTERN COUNTIES OF THE CWA.
MODELS DO NOT SHOW MUCH IN THE WAY OF QPF...HOWEVER MID-LEVEL
MOISTURE WILL LIKELY RESIDE NEAR THE GULF COAST BEFORE THIS TROUGH
MOVES OVER THE REGION TONIGHT. IT SEEMS REASONABLE THAT SOME OF
THIS MOISTURE WILL RETURN ON THE 305K SURFACE (NEAR THE H700 LEVEL
TONIGHT) AND RESULT IN SOME PERSISTENT MID-LEVEL PRECIPITATION
PRODUCTION BEFORE SUNRISE MONDAY.
THE LOWER TROPOSPHERE IS EXPECTED TO BE QUITE DRY BEFORE THIS
PROCESS STARTS...SO A SIGNIFICANT AMOUNT OF THIS MID-LEVEL
PRECIPITATION IS LIKELY TO EVAPORATE BEFORE REACHING THE GROUND.
REGARDLESS...CONFIDENCE IN THE MID-LEVEL PRECIPITATION PRODUCTION
IS HIGH...SO WENT AHEAD AND MENTIONED A 20 PERCENT CHANCE OF RAIN
OR FREEZING RAIN SOUTHEAST OF AN ATHENS TO TEMPLE LINE (NOT
INCLUDING WACO AT THIS TIME) FOR EARLY MONDAY MORNING. DO NOT
THINK THE IMPACTS OF THIS WILL BE HIGH UNLESS THE LOWER ATMOSPHERE
SATURATES QUICKER THAN EXPECTED. LIGHT PRECIPITATION WILL LIKELY
CONTINUE AFTER SUNRISE MONDAY MORNING FOR THESE
LOCATIONS...HOWEVER TEMPERATURES ARE LIKELY TO WARM ABOVE FREEZING
AFTER SUNRISE. WE MAY HAVE TO CONSIDER A WINTER WEATHER OR
FREEZING RAIN ADVISORY IF IT LOOKS LIKE MORE PRECIPITATION WILL
MAKE IT TO THE GROUND...BUT CONFIDENCE IS TOO LOW TO GO WITH
ANYTHING AT THIS TIME.
FOR MID-WEEK...THE ECMWF HAS COME MORE IN LINE WITH THE NAEFS
SOLUTION INDICATING THAT THE LONGWAVE TROUGH OVER THE WESTERN
THIRD OF THE CONUS WILL CONSOLIDATE AND MOVE EAST AS A POSITIVELY
TILTED TROUGH TUESDAY NIGHT INTO WEDNESDAY. THIS SOLUTION LIMITS
LARGE SCALE FORCING FOR ASCENT OVER NORTH AND CENTRAL TX BY
KEEPING LOW LEVEL FLOW VEERED AS IT MOVES OVER THE AREA. THIS
WOULD ALSO PREVENT ANY SIGNIFICANT MOISTURE FROM RETURNING TO THE
REGION OUT AHEAD OF THIS UPPER TROUGH. THE 00 AND 06Z NAM
SOLUTIONS BOTH PREFER THE STRONG AND SLOW MOVING CUT-OFF LOW
SOLUTION ADVERTISED BY THE ECMWF THE PAST FEW DAYS. WHILE THIS
SOLUTION IS AN OUTLIER SOLUTION...WE WILL CONTINUE TO WATCH FOR
ANY SIGN THAT THIS SOLUTION COULD VERIFY AS IT WOULD LIKELY ALLOW
FOR A SIGNIFICANT ICE STORM IN THE REGION IF IT VERIFIED. THIS
FORECAST CONTINUES TO SIDE WITH THE CONSENSUS OF THE NAEFS AND THE
13/00Z ECMWF AS THIS IS BY FAR THE MOST LIKELY OUTCOME. HOWEVER
WILL NOT COMPLETELY IGNORE THE NAM AS IT WOULD BRING A HIGH IMPACT
WINTER WEATHER EVENT TO SOME PART OF NORTH OR CENTRAL TX.
EXTENDED...ONCE THE LONGER WAVE TROUGH MOVES OUT OF THE
REGION...WE SHOULD SEE A SLOW WARMING TREND FOR THE REGION AS A
BLOCKING RIDGE SETS UP OVER THE WESTERN CONUS COAST KEEPING MORE
OR LESS NORTHWEST AND CONFLUENT FLOW OVER THE SOUTH PLAINS. THIS
WARM UP COULD COME TO AN ABRUPT END EARLY NEXT WEEK AS BOTH THE
GFS AND THE ECMWF HAVE A STRONG COLD FRONT MOVING SOUTH THROUGH
THE GREAT PLAINS. THE GFS COOLS US DOWN...BUT ALLOWS THE COLD AIR
TO MODIFY TO THE POINT THAT IT BEHAVES LIKE A TYPICAL WINTER COLD
FRONT FOR TEXAS. THAT IS WE COOL DOWN SIGNIFICANTLY...BUT
OVERNIGHT LOWS TEND TO SAY IN THE MID TO UPPER 20S WHILE HIGHS
CLIMB ABOVE FREEZING.
THE ECMWF BRINGS A SIGNIFICANT ARCTIC OUTBREAK SOUTH THROUGH THE
PLAINS...WHICH WOULD IMPACT NORTH TX SUNDAY NIGHT OR MONDAY IF IT
VERIFIED. THE 13/00Z ECMWF HAS A 1053 MB (MSLP) SURFACE HIGH
BARRELING SOUTH INTO THE CENTRAL PLAINS BEHIND THIS FRONT...WHICH
IS A SIGN OF A VERY COLD ARCTIC AIR INVASION OF THE PLAINS. THIS
IS NOT THE MOST LIKELY SOLUTION TO VERIFY AT THIS TIME...BUT IT
BEARS WATCHING AS WE GET CLOSER TO NEXT WEEKEND AND EARLY NEXT
WEEK. THE ECMWF WOULD BRING LOWS DOWN INTO THE TEENS IF NOT LOWER
ACROSS NORTH TX WHICH COULD CERTAINLY HAVE A BIG IMPACT ON THE
REGION. THIS IS SLIGHTLY BEYOND THE OFFICIAL FORECAST PERIOD AT
THIS TIME...SO WILL WATCH FOR MORE CONSISTENCY AMONGST MODELS
BEFORE JUMPING ON AN ARCTIC OUTBREAK TO START OFF THE NEXT WORK
WEEK.
CAVANAUGH
&&
.PRELIMINARY POINT TEMPS/POPS...
DALLAS-FT. WORTH, TX 42 26 44 28 45 / 10 10 5 10 10
WACO, TX 45 27 43 27 45 / 10 10 10 10 10
PARIS, TX 41 25 44 26 43 / 20 10 10 10 10
DENTON, TX 42 24 43 23 45 / 10 10 5 10 10
MCKINNEY, TX 42 24 44 24 43 / 20 10 10 10 10
DALLAS, TX 42 27 44 29 44 / 10 10 10 10 10
TERRELL, TX 44 26 43 27 43 / 10 10 10 10 10
CORSICANA, TX 44 28 44 30 43 / 10 10 10 10 10
TEMPLE, TX 46 27 43 27 44 / 10 10 10 10 10
MINERAL WELLS, TX 42 22 43 22 44 / 5 10 5 5 10
&&
.FWD WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS LUBBOCK TX
354 AM CST SUN JAN 13 2013
.SHORT TERM...
A SPRAWLING AND COMPLEX UPPER LEVEL TROUGH WAS DOMINATING THE
WESTERN 2/3RDS OF THE CONUS...WITH SEVERAL EMBEDDED DISTURBANCES
NOTED WITHIN IT. ONE SUCH SHORTWAVE TROUGH WAS GRAZING THE AREA
EARLY THIS MORNING...WITH ANOTHER CURRENTLY DIVING DOWN THE SOUTHERN
CALIFORNIA COAST PROGGED TO APPROACH FROM THE WEST LATE TONIGHT. THE
FORMER HAS PROVIDED STRONG ENOUGH LIFT TO PRODUCE A BAND OF SNOW
THAT HAS TRAVERSED THE NORTHWEST AND NORTH-CENTRAL ZONES EARLY THIS
MORNING. EVEN THOUGH THE PRESENTATION ON RADAR WITHIN THIS BAND HAS
NOT BEEN OVERLY IMPRESSIVE AND MOISTURE IS RATHER LIMITED...THE BAND
HAS BEEN ABLE TO SQUEEZE OUT EFFICIENT SNOW RATES GIVEN THE COLD
TEMPERATURES AND HIGH SNOW TO LIQUID RATIOS. FRIONA REPORTED A QUICK
1-2 INCHES OF SNOW AS THE BAND MOVED THROUGH EARLIER THIS
MORNING...WITH DIMMITT AND TULIA REPORTING LESS THAN 1 INCH. LIFT
SUPPORTING THIS BAND WILL GRADUALLY WANE MOVING TOWARDS
DAYBREAK...BUT A LITTLE LIGHT SNOW OR FLURRIES COULD LINGER PAST 12Z
ACROSS THE NORTHEAST ZONES.
OTHERWISE...COLD SFC RIDGING WILL DOMINATE THE REGION THROUGH THE
SHORT TERM. LOW STRATUS CLOUDS HAVE DEVELOPED ACROSS ROUGHLY THE
NORTHWEST HALF OF THE CWA IN THIS REGIME EARLY THIS MORNING. BOTH
THE NAM AND GFS SUGGEST THESE CLOUDS WILL QUICKLY SCATTER OUT THIS
MORNING AS MID- AND UPPER-LEVEL SUBSIDENCE INCREASES IN THE WAKE OF
THE PASSING SHORTWAVE TROUGH. ON THE OTHER HAND...THE RUC AND HRRR
SUGGEST THAT THE LOW CLOUDS MAY HANG ON MUCH OR ALL OF THE DAY ON
THE CAPROCK AS WINDS VEER EASTERLY AND THE SHALLOW BUT RELATIVELY
MOIST UPSLOPE FLOW ENSUES. CURRENT FORECAST IN THE GRIDS DOES
INDICATE CLEARING SKIES BY MIDDAY...BUT IF THIS DOES NOT
OCCUR...FORECAST HIGHS WILL LIKELY BE TOO HIGH. REGARDLESS...IT WILL
BE A CHILLY DAY AND HAVE FAVORED THE LOW SIDE OF MOS GUIDANCE WITH
FORECAST HIGHS IN THE LOWER TO MIDDLE 30S FOR ALL BUT THE NORTHWEST
ZONES WHERE UPPER 20S WERE CARRIED.
CHILLY EASTERLY UPSLOPE FLOW WILL CONTINUE THROUGH TONIGHT. PROGGED
SOUNDINGS INDICATE MOSTLY CLEAR SKIES EARLY ON...WITH SOME MID-LEVEL
CLOUDS VISITING AT LEAST THE NORTHWEST ZONES LATE AS THE NEXT
SHORTWAVE TROUGH RACES BY. HOWEVER...GIVEN THE UPSLOPE FLOW WOULD
NOT BE SURPRISED IF SOME LOWER CLOUDS DEVELOP OR PERSIST. ALTHOUGH
MODELS ARE GENERALLY DRY...THINK THERE MAY BE ENOUGH LIFT AND
MOISTURE TO SQUEEZE OUT A FEW FLURRIES ACROSS THE WESTERN ZONES LATE
TONIGHT AND HAVE INSERTED THIS INTO THE FORECAST. EXTENT AND
DURATION OF ANY CLOUD COVER COULD HAVE SOME IMPACTS ON EXACTLY HOW
COLD IT GETS TONIGHT...BUT EITHER WAY IT WILL BE CHILLY AND HAVE
MAINTAINED LOWS 10-15 DEGREES BELOW MID-JANUARY AVERAGES /RANGING
FROM 9 DEGREES NORTHWEST TO MID-TEENS OUT EAST/.
&&
.LONG TERM...
THE MON THRU THU FORECAST HINGES ON THE STRENGTH AND TRACK OF THE
SRN PORTION OF THE UPPER-LEVEL TROUGH...INITIALLY LOCATED OVER AZ
AND NM MONDAY MORNING. THE MAJORITY OF GUIDANCE ELONGATES THE TROUGH
FROM THE SW TO NE AS IT SLIDES SEWD ACROSS WEST TEXAS...WITH
MOISTURE AND LIFT BOTH LACKING TO WRING OUT ANY PRECIPITATION FOR
OUR AREA...BEFORE IT EVENTUALLY CLOSES OFF AT 500 MB ACROSS NORTH
CENTRAL TX. HOWEVER...THERE ARE STILL A FEW MODELS /E.G. 0Z NAM
AND CMC/ AND SOME GEFS ENSEMBLE MEMBERS THAT CLOSED OFF TROUGH
INTO A CUTOFF LOW ACROSS SRN NM OR NRN MX...THEN TRACK IT SLOWLY
EAST ACROSS WEST TEXAS MID-WEEK. IN THE LATTER CASE COULD BRING
A CHANCE OF SOME RAIN OR SNOW IN THE TUE THRU THU TIME FRAME AS
BOTH MOISTURE ADVECTION AND LIFT WOULD BE ENHANCED. BUT
PREPONDERANCE OF GUIDANCE SUGGESTS THE OPEN WAVE PASSAGE
ACCOMPANIED BY ONLY AN INCREASE IN MID-LVL CLOUD COVER. THUS WE/VE
KEPT POPS BELOW MENTION THROUGH THE EXTENDED PERIOD...ALTHOUGH
NUDGED THEM UP TO 10 PERCENT ACROSS OUR SRN ZONES. MONDAY STILL
APPEARS TO BE THE COOLEST DAY IN THE PERIOD...WITH HIGHS ONLY IN
THE LOW TO MID 30S. TUESDAY WILL ONLY BE SLIGHTLY WARMER...WITH
HIGHS IN THE UPPER 30S TO LOW 40S. FINALLY...BARRING THE CLOSED
LOW SOLUTION...HIGHS WILL WARM BACK INTO THE UPPER 40S AND 50S WED
AND THU.
FRI-SAT: AFTER THE TROUGH/LOW PASSES...WEAK ZONAL TO SW FLOW SHOULD
EXTEND OVER THE AREA AS A BROAD LOW-AMPLITUDE TROUGH DEVELOPS OVER
THE DESERT SOUTHWEST. SOME SUB-TROPICAL MOISTURE MAY GET DRAWN UP BY
THE TROUGH TO BRING SOME HIGH CLOUD COVER TO THE AREA BY FRIDAY. AND
JUST TO OUT NORTH...UPPER FLOW WILL BECOME CYCLONIC AS A DEEP
TROUGH DROPS INTO THE GREAT LAKES REGION...WHILE THE UPPER RIDGE RE-
AMPLIFIES ALONG THE PACIFIC COAST. TEMPS WILL CONTINUE TO BE MILD
WITH HIGHS MAINLY IN THE MID TO UPPER 50S.
A WEAK FRONT IS EXPECTED TO MOVE INTO THE AREA BY SUNDAY...RESULTING IN
A MODEST COOL DOWN DEPENDING ON THE TIMING OF THE FROPA. A MUCH
STRONGER FRONT IS POSSIBLE BY MONDAY THE 21ST...AS A 1050MB SFC RIDGE
DIVES OUT OF CENTRAL CANADA INTO THE PLAINS. IT IS STILL TOO EARLY
TO TELL IF THIS COLD AIR MASS WILL SETTLE INTO WEST TEXAS OR IF
WE/LL ONLY RECEIVE A GLANCING BLOW.
&&
.PRELIMINARY POINT TEMPS/POPS...
FRIONA 28 9 29 9 37 / 10 10 10 10 10
TULIA 29 10 30 12 38 / 10 0 10 10 10
PLAINVIEW 31 11 31 11 38 / 10 10 10 10 10
LEVELLAND 34 11 32 12 38 / 10 10 10 10 10
LUBBOCK 33 12 33 13 39 / 10 10 0 10 10
DENVER CITY 36 13 32 12 38 / 10 10 10 10 10
BROWNFIELD 36 12 32 13 38 / 10 10 0 10 10
CHILDRESS 35 15 34 15 41 / 20 0 0 0 10
SPUR 35 14 34 15 40 / 10 0 0 0 10
ASPERMONT 37 16 36 14 41 / 0 0 10 0 10
&&
.LUB WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
23/33
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
739 AM CST SUN JAN 13 2013
.SHORT TERM...
739 AM CST SUN JAN 13 2013
BANDS OF FLURRIES AND LIGHT SNOW HAS DEVELOPED AHEAD OF A TROUGH
OVER CENTRAL WISCONSIN. THE RAP IS HANDLING THE MOISTURE
ASSOCIATED WITH THIS TROUGH THE BEST...SO TRENDED THE FORECAST
TOWARD IT. LITTLE...IF ANY...ACCUMULATION IS EXPECTED THIS MORNING.
.LONG TERM...TUESDAY NIGHT THROUGH SATURDAY
212 AM CST SUN JAN 13 2013
NORTHWEST FLOW ALOFT IS EXPECTED TO BE OVER THE UPPER MIDWEST
THROUGH THE PERIOD AS THE POLAR VORTEX SHIFTS SOUTH ACROSS HUDSON
BAY AND THEN TOWARD THE ATLANTIC. A COUPLE OF SHORT WAVE TROUGHS
SHOULD PASS OVER THE REGION IN THIS NORTHWEST FLOW. MODELS HAVE
NOW SETTLED IN ON THE TIMING OF THE FIRST WAVE COMING ACROSS
TUESDAY NIGHT AND WEDNESDAY. THIS WILL CAUSE A SURFACE LOW TO MOVE
ACROSS SOUTHERN CANADA WITH A COLD FRONT PASSING THROUGH WEDNESDAY.
THE 13.00Z ECMWF SUGGESTS THE POTENTIAL FOR SOME LIGHT SNOW TO
LINGER INTO WEDNESDAY NIGHT BUT THIS MAY END UP BEING SOME LAKE
EFFECT SNOW OFF OF LAKE SUPERIOR THAT STAYS NORTH OF THE AREA.
PLAN TO CARRY SOME LIGHT SNOW CHANCES FOR TUESDAY NIGHT AND
WEDNESDAY. THE NEXT SHORT WAVE TROUGH AND SURFACE LOW IS PRESENTLY
EXPECTED TO COME ACROSS THURSDAY NIGHT BUT SOME QUESTION AS
WHETHER THIS SYSTEM WILL BE ABLE TO PRODUCE ANY LIGHT SNOW WITH
SATURATION A CONCERN. AFTER THAT...ANOTHER WAVE WILL COME THROUGH
SATURDAY BUT DIFFERENCES ON THE TRACK OF THE SURFACE LOW WITH THE
GFS SOUTH OF THE AREA AND THE ECMWF WELL TO THE NORTH. WILL STAY
WITH THE MODEL CONSENSUS GRIDS AND SHOW A CHANCE OF LIGHT SNOW
ACROSS THE NORTH.
&&
.AVIATION...TODAY AND TONIGHT
620 AM CST SUN JAN 13 2013
A TROUGH NORTH OF INTERSTATE 94 IS BRINGING AREAS OF MVFR CLOUDS
INTO THE TAF SITES. OVERALL THE RAP IS HANDLING THESE CLOUDS THE
BEST SO TRENDED THE FORECAST TOWARD IT. KLSE WILL SEE A BROKEN
DECK OF MVFR CLOUDS THROUGH 13.21Z. KRST LOOKS LIKE THEY WILL BE
ON THE WESTERN PERIPHERY OF THESE CLOUDS...SO JUST PUT A TEMPO
GROUP OF BROKEN MVFR CLOUDS THROUGH 13.19Z. SUBSIDENCE IN THE WAKE
OF TROUGH WILL RESULT IN SCATTERED DECK OF 3000 FOOT CLOUDS FROM
LATE THIS AFTERNOON THROUGH TONIGHT.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
212 AM CST SUN JAN 13 2013
WI...NONE.
MN...NONE.
IA...NONE.
&&
$$
SHORT TERM...BOYNE
LONG TERM...04
AVIATION...BOYNE
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
621 AM CST SUN JAN 13 2013
.SHORT TERM...THROUGH TUESDAY
212 AM CST SUN JAN 13 2013
SURFACE ANALYSIS THIS MORNING SHOWS AN AREA OF LOW PRESSURE OVER
CENTRAL INDIANA AND HIGH PRESSURE OVER SOUTH DAKOTA.
REGIONAL RADARS THIS MORNING SHOWING SOME LIGHT SNOW FALLING ON
THE NORTHWEST SIDE OF THE INDIANA SURFACE LOW. THIS SNOW IS
FALLING OVER EXTREME EASTERN IOWA INTO NORTHERN ILLINOIS AND
SOUTHEAST WISCONSIN. DESPITE THE LOCAL RADAR SHOWING SOME ECHOES
OVER PARTS OF ADAMS...RICHLAND AND GRANT COUNTIES NOTHING IS
HITTING THE GROUND AS THERE IS JUST TOO MUCH LOW LEVEL DRY AIR IN
PLACE WITH TEMP/DEW POINT SPREADS OF 7 TO 10 DEGREES. EVEN DRIER
AIR IS JUST OFF TO THE WEST SO NOT ANTICIPATING ANY SNOW REACHING
THE GROUND IN THE FORECAST AREA...ESPECIALLY AS THE SURFACE LOW
CONTINUES TO PULL AWAY FROM THE AREA. SOME FLURRIES MAY FALL TODAY
OVER THE NORTHERN SECTIONS OF THE FORECAST AREA AS A TROUGH OF LOW
PRESSURE IS EXPECTED TO EXTEND FROM THE SURFACE LOW AS IT GETS
INTO NORTHERN LOWER MICHIGAN BACK ACROSS NORTHERN WISCONSIN INTO
MINNESOTA. A BAND OF LOWER CONDENSATION PRESSURE DEFICITS ON THE
270K SURFACE WILL RESIDE NEAR THE TROUGH. THE 13.00Z NAM BUFKIT
SOUNDINGS SHOW LITTLE TO NO VERTICAL MOTION ALONG THE TROUGH WHILE
THE 13.00Z GFS DOES HINT AT SOME WEAK LIFT. EVEN IF THE GFS IS
CORRECT...THE VERTICAL MOTION IS NOT ENOUGH TO PRODUCE MORE THAN
FLURRIES.
THE AREA OF HIGH PRESSURE WILL EXPAND OVER THE UPPER MIDWEST
TONIGHT...REMAINING THROUGH MONDAY NIGHT BEFORE SLIPPING OFF TO
THE SOUTHEAST TUESDAY. AN AREA OF LOW PRESSURE WILL MOVING
SOUTHEAST ACROSS MANITOBA AND SASKATCHEWAN TUESDAY AND THE FLOW
WILL TURN TO THE SOUTHWEST BETWEEN THE LOW AND DEPARTING HIGH.
WITH WARMER AIR COMING IN ON THE SOUTHWEST FLOW...TEMPERATURES ARE
EXPECTED TO WARM INTO THE MIDDLE 20S TO LOWER 30S. WITH THE LACK
OF SNOW COVER...THERE IS THE POTENTIAL THAT THESE COULD GO EVEN
HIGHER WITH THE 12.12Z ECMWF BEING ABOUT A CATEGORY WARMER.
.LONG TERM...TUESDAY NIGHT THROUGH SATURDAY
212 AM CST SUN JAN 13 2013
NORTHWEST FLOW ALOFT IS EXPECTED TO BE OVER THE UPPER MIDWEST
THROUGH THE PERIOD AS THE POLAR VORTEX SHIFTS SOUTH ACROSS HUDSON
BAY AND THEN TOWARD THE ATLANTIC. A COUPLE OF SHORT WAVE TROUGHS
SHOULD PASS OVER THE REGION IN THIS NORTHWEST FLOW. MODELS HAVE
NOW SETTLED IN ON THE TIMING OF THE FIRST WAVE COMING ACROSS
TUESDAY NIGHT AND WEDNESDAY. THIS WILL CAUSE A SURFACE LOW TO MOVE
ACROSS SOUTHERN CANADA WITH A COLD FRONT PASSING THROUGH WEDNESDAY.
THE 13.00Z ECMWF SUGGESTS THE POTENTIAL FOR SOME LIGHT SNOW TO
LINGER INTO WEDNESDAY NIGHT BUT THIS MAY END UP BEING SOME LAKE
EFFECT SNOW OFF OF LAKE SUPERIOR THAT STAYS NORTH OF THE AREA.
PLAN TO CARRY SOME LIGHT SNOW CHANCES FOR TUESDAY NIGHT AND
WEDNESDAY. THE NEXT SHORT WAVE TROUGH AND SURFACE LOW IS PRESENTLY
EXPECTED TO COME ACROSS THURSDAY NIGHT BUT SOME QUESTION AS
WHETHER THIS SYSTEM WILL BE ABLE TO PRODUCE ANY LIGHT SNOW WITH
SATURATION A CONCERN. AFTER THAT...ANOTHER WAVE WILL COME THROUGH
SATURDAY BUT DIFFERENCES ON THE TRACK OF THE SURFACE LOW WITH THE
GFS SOUTH OF THE AREA AND THE ECMWF WELL TO THE NORTH. WILL STAY
WITH THE MODEL CONSENSUS GRIDS AND SHOW A CHANCE OF LIGHT SNOW
ACROSS THE NORTH.
&&
.AVIATION...TODAY AND TONIGHT
620 AM CST SUN JAN 13 2013
A TROUGH NORTH OF INTERSTATE 94 IS BRINGING AREAS OF MVFR CLOUDS
INTO THE TAF SITES. OVERALL THE RAP IS HANDLING THESE CLOUDS THE
BEST SO TRENDED THE FORECAST TOWARD IT. KLSE WILL SEE A BROKEN
DECK OF MVFR CLOUDS THROUGH 13.21Z. KRST LOOKS LIKE THEY WILL BE
ON THE WESTERN PERIPHERY OF THESE CLOUDS...SO JUST PUT A TEMPO
GROUP OF BROKEN MVFR CLOUDS THROUGH 13.19Z. SUBSIDENCE IN THE WAKE
OF TROUGH WILL RESULT IN SCATTERED DECK OF 3000 FOOT CLOUDS FROM
LATE THIS AFTERNOON THROUGH TONIGHT.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
212 AM CST SUN JAN 13 2013
WI...NONE.
MN...NONE.
IA...NONE.
&&
$$
SHORT TERM...04
LONG TERM...04
AVIATION...BOYNE
AREA FORECAST DISCUSSION
NWS GOODLAND KS
1149 PM MST MON JAN 14 2013
.SHORT TERM...(THIS AFTERNOON THROUGH TUESDAY)
ISSUED AT 111 PM MST MON JAN 14 2013
CURRENT WV IMAGERY AND RUC H5 ANALYSIS SHOW LARGE TROUGH EXTENDING
FROM CANADA ACROSS THE PLAINS AND SW US TO THE BAJA PENINSULA. MEAN
AXIS IS CURRENTLY UPSTREAM OF CWA ALONG THE CENTRAL ROCKIES WITH
SURFACE TROUGH ALONG FRONT RANGE.
RUC INDICATES AXIS OF H85-H7 FRONTOGENESIS IN PLACE ACROSS EASTERN
COLORADO AND FAR WESTERN KANSAS WHERE LIGHT SNOW HAS BEEN FALLING
FOR MOST OF THE DAY. AS THE UPPER LEVEL TROUGH SHIFTS EAST THIS
EVENING THIS AXIS OF FORCING WILL BEGIN TO WEAKEN AND SHIFT
SOUTH...WITH SNOW COMING TO AN END OVER OUR SW CWA BY 03Z. I
COULD NOT RULE OUT ADDITIONAL SNOW ACCUMULATION AROUND ONE INCH
ALONG AN AXIS FROM STRATTON COLORADO TO BENKELMAN NEBRASKA THROUGH
THIS AFTERNOON WHERE RADAR SHOWS SOME INTENSIFICATION...HOWEVER
MOST LOCATIONS SHOULD SEE LESS THAN ONE HALF INCH TOTAL SNOW
ACCUMULATION FOR THIS EVENT. SUBSIDENCE AND A DRY AIR MASS WILL
BEGIN TO WORK IN OVER THE CWA AFTER MIDNIGHT WITH CLEARING SKIES
FROM THE NORTHWEST OVERNIGHT. THERE WILL BE LITTLE CHANGE IN THE
COLD AIRMASS FROM LAST NIGHT...SO DEPENDING ON HOW QUICKLY
CLOUDS CLEAR WE COULD SEE NEGATIVE TEMPERATURES ONCE AGAIN OVER
PARTS OF THE CWA. FOR NOW I LIMITED COLDEST TEMPS TO THE NORTH AND
WEST WHERE CLOUDS ARE MOST LIKELY TO CLEAR BEFORE SUNRISE.
AIRMASS WILL BEGIN TO MODERATE BY MIDDAY TUESDAY AS LEE TROUGH
DEVELOPS AND WINDS SHIFT TO THE WEST. IT IS A TOUGH CALL ON WHAT
IMPACT LINGERING SNOW PACK WILL HAVE...HOWEVER WE SHOULD SEE
TEMPERATURES IN THE LOW TO MID 30S ACROSS ALL THE CWA...WITH A FEW
LOCATIONS IN THE SOUTH AND EAST POSSIBLY WARMER.
.LONG TERM...(FRIDAY THROUGH TUESDAY)
ISSUED AT 1141 PM MST MON JAN 14 2013
UPPER PATTERN FOR THE PERIOD WILL FEATURE A RIDGE OVER THE WESTERN
CONUS AND A TROUGH OVER THE EAST...LEAVING THE CENTRAL PLAINS
UNDER NORTHWEST FLOW. FRIDAY AND SATURDAY WILL BE DRY WITH
TEMPERATURES SLIGHTLY ABOVE NORMAL. A BACK DOOR COLD FRONT
ASSOCIATED WITH A DISTURBANCE MOVING THROUGH THE FLOW IN THE
NORTHERN PLAINS WILL MOVE INTO THE LOCAL AREA SOMETIME ON
SUNDAY...FOLLOWED BY A REINFORCING SHOT OF COLD AIR ON MONDAY.
SINCE THE UPPER DYNAMICS WILL STAY FAR TO THE NORTHEAST...NO
PRECIPITATION IS EXPECTED WITH EITHER FRONT. MODELS DISAGREE ON
HOW COLD IT WILL GET WITH THE FRONTS...PARTICULARLY ON MONDAY...BUT
THE EXTENDED INITIALIZATION ALGORITHM ESSENTIALLY SPLIT THE
DIFFERENCE WHICH IS AS GOOD AN APPROACH AS ANY AT THIS TIME RANGE.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z TUESDAY NIGHT)
ISSUED AT 954 PM MST MON JAN 14 2013
VFR CONDITIONS WILL CONTINUE AT KGLD AND KMCK FOR THE NEXT 24
HOURS. CLEARING WILL OCCUR AT BOTH SITES BY SUNRISE AND THEN
CLOUDS WILL INCREASE AGAIN TUESDAY EVENING AS THE NEXT DISTURBANCE
COMES THROUGH NORTHERLY FLOW INTO THE AREA. SOME FLURRIES WILL BE
POSSIBLE AT BOTH SITES DURING THE EVENING.
&&
.GLD WATCHES/WARNINGS/ADVISORIES...
KS...NONE.
CO...NONE.
NE...NONE.
&&
$$
SHORT TERM...DR
LONG TERM...024
AVIATION...032
AREA FORECAST DISCUSSION
NWS GOODLAND KS
1020 PM MST MON JAN 14 2013
.SHORT TERM...(THIS AFTERNOON THROUGH TUESDAY)
ISSUED AT 111 PM MST MON JAN 14 2013
CURRENT WV IMAGERY AND RUC H5 ANALYSIS SHOW LARGE TROUGH EXTENDING
FROM CANADA ACROSS THE PLAINS AND SW US TO THE BAJA PENINSULA. MEAN
AXIS IS CURRENTLY UPSTREAM OF CWA ALONG THE CENTRAL ROCKIES WITH
SURFACE TROUGH ALONG FRONT RANGE.
RUC INDICATES AXIS OF H85-H7 FRONTOGENESIS IN PLACE ACROSS EASTERN
COLORADO AND FAR WESTERN KANSAS WHERE LIGHT SNOW HAS BEEN FALLING
FOR MOST OF THE DAY. AS THE UPPER LEVEL TROUGH SHIFTS EAST THIS
EVENING THIS AXIS OF FORCING WILL BEGIN TO WEAKEN AND SHIFT
SOUTH...WITH SNOW COMING TO AN END OVER OUR SW CWA BY 03Z. I
COULD NOT RULE OUT ADDITIONAL SNOW ACCUMULATION AROUND ONE INCH
ALONG AN AXIS FROM STRATTON COLORADO TO BENKELMAN NEBRASKA THROUGH
THIS AFTERNOON WHERE RADAR SHOWS SOME INTENSIFICATION...HOWEVER
MOST LOCATIONS SHOULD SEE LESS THAN ONE HALF INCH TOTAL SNOW
ACCUMULATION FOR THIS EVENT. SUBSIDENCE AND A DRY AIR MASS WILL
BEGIN TO WORK IN OVER THE CWA AFTER MIDNIGHT WITH CLEARING SKIES
FROM THE NORTHWEST OVERNIGHT. THERE WILL BE LITTLE CHANGE IN THE
COLD AIRMASS FROM LAST NIGHT...SO DEPENDING ON HOW QUICKLY
CLOUDS CLEAR WE COULD SEE NEGATIVE TEMPERATURES ONCE AGAIN OVER
PARTS OF THE CWA. FOR NOW I LIMITED COLDEST TEMPS TO THE NORTH AND
WEST WHERE CLOUDS ARE MOST LIKELY TO CLEAR BEFORE SUNRISE.
AIRMASS WILL BEGIN TO MODERATE BY MIDDAY TUESDAY AS LEE TROUGH
DEVELOPS AND WINDS SHIFT TO THE WEST. IT IS A TOUGH CALL ON WHAT
IMPACT LINGERING SNOW PACK WILL HAVE...HOWEVER WE SHOULD SEE
TEMPERATURES IN THE LOW TO MID 30S ACROSS ALL THE CWA...WITH A FEW
LOCATIONS IN THE SOUTH AND EAST POSSIBLY WARMER.
.LONG TERM...(TUESDAY NIGHT THROUGH MONDAY)
ISSUED AT 233 PM MST MON JAN 14 2013
FORECAST PROBLEMS WILL BE AMOUNT OF WARMUP DURING THE EARLY PORTION
OF THIS PERIOD FOLLOWED BY HOW MUCH TO COOL IT DOWN AT THE END OF
THE PERIOD. SATELLITE SHOWING AN AMPLIFIED FLOW STARTING WITH A
BROAD...DEEP AND COMPLICATED UPPER TROUGH OVER THE WESTERN HALF OF
THE PACIFIC WHICH IS MAINTAINING/AMPLIFYING AN UPPER RIDGE NEAR THE
WEST COAST OF NORTH AMERICA. THIS TRANSITIONS TO A TROUGH OVER THE
CENTER OF THE COUNTRY WHICH HAS/CONTINUES TO SPLIT. COLD AIR REMAINS
OVER THE AREA AND UPSTREAM AT THIS TIME.
MODELS INITIALIZED FINE AT JET LEVEL. HOWEVER...THEY WERE A LITTLE
UNDERDONE ON THE SPEEDS BEHIND THE UPPER TROUGH OVER THE COUNTRY.
THE GFS WAS DOING A LITTLE BETTER THAN THE CANADIAN AND NAM. MODELS
INITIALIZED FINE AT MID LEVELS WITH THE ECMWF AND UKMET DOING A
LITTLE BETTER THAN THE GFS AND CANADIAN. THE ECMWF WAS DOING THE
BEST AT THE SURFACE. THE ECMWF WAS DOING A LITTLE BETTER THAN THE
GFS...UKMET AND CANADIAN ON THE LOW LEVEL THERMAL FIELD.
TUESDAY NIGHT/WEDNESDAY...LEFT FRONT QUADRANT OF THE JET MOVES
ACROSS DURING THE NIGHT. UPPER TROUGH WILL HAVE MOVED EAST OF THE
AREA BY THE BEGINNING OF THIS PERIOD. IN ADDITION TO THE LIFT FROM
THE JET...MOISTURE INCREASES THROUGH MID LEVELS ON THE WEST SIDE OF
THE TROUGH. THERE IS SOME MODERATE FRONTOGENESIS AS WELL. LAPSE
RATES ARE NOT THAT GREAT. HOWEVER WITH THE COLD AIR IN PLACE AND THE
MODELS SHOWING DEEP ENOUGH MOISTURE...WILL INSERT FLURRIES INTO
THE NORTHWEST HALF SINCE THE SYNOPTIC LIFT IS NOT THAT GREAT BUT
MESOSCALE FORCING IS PRETTY GOOD. WHATEVER FALLS SHOULD BE DONE BY
06Z.
AFTER THE FLURRIES END...SUBSIDENCE INCREASE BEHIND JET AND UPPER
TROUGH. SO WINDS COULD BECOME BREEZY FROM A DOWNSLOPE DIRECTION FOR
A SHORT PERIOD OF TIME. THIS SHOULD MAKE THE MINS WARMER AND DID
WARM THEM SOME BUT MAYBE NOT ENOUGH. PLENTY OF SUN AND DOWNSLOPE
WINDS SHOULD MAKE FOR A MUCH WARMER DAY THAN WE HAVE BEEN HAVING
LATELY. IN GENERAL...MAXES SHOULD RANGE FROM THE MIDDLE 40S TO NEAR
50 DEGREES.
WEDNESDAY NIGHT/THURSDAY...DOWNSLOPE WINDS SHOULD KEEP MINS WARMER
AGAIN. WILL HAVE PLENTY OF SUN BUT NOT AS FAVORABLE OF A WIND FIELD.
NEW GUIDANCE INDICATES HIGH TEMPERATURES SIMILAR TO WEDNESDAYS AND
DID NOT CHANGE MUCH.
THURSDAY NIGHT THROUGH MONDAY...CURRENT AMPLIFIED PATTERN FLATTENS
OUT A LITTLE BIT EARLY IN THE PERIOD BEFORE BECOMING VERY AMPLIFIED
BY THE END OF THE PERIOD ONCE AGAIN. THROUGH FRIDAY SHOULD MAINTAIN
HIGH TEMPERATURES VERY SIMILAR TO WHAT THEY WERE ON WEDNESDAY AND
THURSDAY. THEN A BIG CHANGE IS GOING TO OCCUR IN TEMPERATURE BUT
WITH UNCERTAINTY IN TIMING AND MAGNITUDE OF THIS TEMPERATURE.
GIVEN WHAT THE PATTERN IS...HAVING A MUCH COLDER AIR MASS INTRUDE
INTO THE REGION IS PRETTY MUCH A GIVEN BUT THE MODELS DISAGREE ON
HOW FAST THEY WHAT TO DO IT. THE GFS AND CANADIAN BRING IN THE
COOLER AIR FASTER WHICH IS FROM LATE SATURDAY AFTERNOON INTO THE
NIGHT. THE 00Z AND 12Z ECMWF PRETTY MUCH KEEP THE COLDER AIR OUT
DURING THE DAY ON SATURDAY. HOWEVER...THE 12Z ECMWF IS MUCH QUICKER
THAN THE OLD RUN IN BRINGING THE COLDER AIR ON SATURDAY NIGHT AND
SUNDAY WHICH A BIG DIFFERENCE ON SUNDAY MAXES. MODELS IN BETTER
AGREEMENT AND MUCH BETTER THAN EARLIER IN BRINGING IN AN ABSOLUTELY
FRIGID AIR MASS SUNDAY NIGHT INTO MONDAY.
THROUGH SATURDAY NIGHT LEFT IN WHAT THE CRH_INIT GAVE ME ALTHOUGH IT
IS POSSIBLE THAT SATURDAY AND SATURDAY NIGHT TEMPERATURES COULD BE
COLDER. FELT PER THE AMPLIFIED PATTERN MAKING THE AREA SUSCEPTIBLE
TO HAVING MUCH COLDER AIR BROUGHT IN...SIGNIFICANT SNOW FIELD OVER
THE NORTH CENTRAL PORTION OF THE COUNTRY...AND MORE MODEL SUPPORT FOR
A SOONER ARRIVING COLD AIR MASS WHICH IS NOT UNCOMMON WITH THIS
MAGNITUDE OF COLD AIR...ADJUSTED THE TEMPERATURES...ESPECIALLY THE
MAXES FOR SUNDAY AND MONDAY...DOWN FROM THE INIT. CONSIDERING THE
AIR MASS WE HAVE HAD IN PLACE FOR THE LAST FEW DAYS AND WHAT THE
MODELS ARE SHOWING...THESE TEMPERATURES WILL PROBABLY NOT BE COLD
ENOUGH...BUT STARTED THE TREND DOWN.
IN REGARDS TO THE PRECIPITATION...LEFT WHAT THE CRH_INIT GAVE ME
WHICH HAS IT DRY DURING THE ENTIRE PERIOD. ALTHOUGH WOULD NOT BE
SURPRISED TO SEE SOME FLURRIES WHEN THE COLD AIR MASS BEGINS TO
ENTER THE AREA.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z TUESDAY NIGHT)
ISSUED AT 954 PM MST MON JAN 14 2013
VFR CONDTIIONS WILL CONTINUE AT KGLD AND KMCK FOR THE NEXT 24
HOURS. CLEARING WILL OCCUR AT BOTH SITES BY SUNRISE AND THEN
CLOUDS WILL INCREASE AGAIN TUESDAY EVENING AS THE NEXT DISTURBANCE
COMES THROUGH NORTHERLY FLOW INTO THE AREA. SOME FLURRIES WILL BE
POSSIBLE AT BOTH SITES DURING THE EVENING.
&&
.GLD WATCHES/WARNINGS/ADVISORIES...
KS...NONE.
CO...NONE.
NE...NONE.
&&
$$
SHORT TERM...DR
LONG TERM...BULLER
AVIATION...032
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
500 AM EST TUE JAN 15 2013
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 500 AM EST TUE JAN 15 2013
WV IMAGERY AND RUC ANALYSIS INDICATED A RIDGE OFF THE WEST COAST AND
A BROAD MID/UPPER LEVEL TROUGH FROM NW OF HUDSON BAY THROUGH NRN
MANITOBA/NW ONTARIO AND THE CNTRL PLAINS INTO NEW MEXICO. THE NEXT
SIGNIFICANT SHORTWAVE TROUGH WAS WELL UPSTREAM YET OVER NW CANADA. AT
THE SFC...A RIDGE EXTENDED FROM THE MID MS VALLEY INTO THE SRN GREAT
LAKES RESULTING IN WSW FLOW THROUGH THE NRN LAKES. WEBCAMS AND MODEL
FCSTS SUGGEST THAT THE HEAVER LES BANDS HAD LIFTED MAINLY NORTH OF
CALUMET INTO THE N AND W PORTIONS OF KEWEENAW COUNTY. WAA 925-700 MB
WAA HELPED SUPPORT AN ARE OF LOW/MID CLOUDS AND A FEW FLURRIES FROM NRN
MN INTO NW WI AND WRN UPPER MI.
EXPECT THAT AS WINDS CONTINUE TO BACK THIS MORNING...ANY REMAINING
LES OVER THE TIP OF THE KEWEENAW WILL LIFT OUT INTO LAKE SUPERIOR
AROUND OR SLIGHTLY AFTER 12Z. SO...THE LES WARNING WILL BE ALLOWED
TO EXPIRE. OTHERWISE...NAM/RUC 925-700 MB RH FCST SUGGESTS THAT THE
CLOUDS SHOULD THIN OUT ENOUGH BY THIS AFTERNOON FOR AT LEAST SOME
SUNSHINE. TEMPS SHOULD CLIMB TO NEAR SEASONAL AVERAGES IN TO THE LOW
TO MID 20S.
THE MODELS WERE IN GOOD AGREEMENT WITH THE POSITION AND SPEED OF THE
NW CANADA CLIPPER SHRTWV MOVING TO JUST NW OF LAKE SUPERIOR BY
12Z/WED. THE GFS...AS IS OFTEN THE CASE WAS MORE AGGRESSIVE IN
SPREADING PCPN EASTWARD THROUGH UPPER MICHIGAN LATE TONIGHT COMPARED
TO THE NAM WHICH BARELY BRINGS ANY QPF TO THE WEST BEFORE 12Z.
ALTHOUGH THE DRY AIRMASS MAY DELAY THE ARRIVAL OF LIGHT SNOW AT THE
SURFACE...THE QVECTOR CONV AHEAD OF THE SHRTWV AND UPPER LEVEL DIV
WITH THE LEFT EXIT OF THE 250-300 MB JET STILL SHOULD BE ENOUGH FOR
LIKELY POPS OVER THE FAR WEST AND CHANCE POPS OVER THE REST OF THE
WEST HALF. SNOW AMOUNTS WILL BE LIGHT AS ONLY A FEW HUNDREDTHS QPF
SUPPORTS ACCUMULATIONS OF ONLY AROUND A HALF INCH OR LESS.
.LONG TERM...(WEDNESDAY THROUGH MONDAY)
ISSUED AT 500 AM EST TUE JAN 15 2013
LONG TERM PERIOD WILL BE DOMINATED BY NORTHWEST FLOW ALOFT AS AN
UPPER LOW SPINS NEAR HUDSON BAY. THIS WILL LEAD TO A SERIES OF
CLIPPER SYSTEMS AND ASSOCIATED COLDER AIR AND LAKE EFFECT ON THE
BACK SIDE.
THE FIRST SYSTEM WILL BE MOVING THROUGH AT THE START OF THE LONG
TERM PERIOD. THIS WAVE...CURRENTLY ROUNDING THE UPPER RIDGE ALONG
THE WESTERN COAST OF NORTH AMERICA...WILL BE SLIDING ACROSS LAKE
SUPERIOR WEDNESDAY MORNING. AT THE SURFACE...A COLD FRONT WILL BE
STRETCHED FROM A LOW IN SOUTHERN HUDSON BAY AND BE SWEEPING THROUGH
THE CWA THROUGH EARLY AFTERNOON. THE WIDESPREAD MOISTURE IS ACROSS
THE NORTH HALF OF THE CWA...WHILE A THIN RIBBON OF DEEP MOISTURE
MOVES ACROSS THE CWA LATE TONIGHT AND WEDNESDAY MORNING. ALTHOUGH
IT APPEARS THE SYSTEM WILL BE FIGHTING DRY LOW LEVEL AIR TO
START...MOST OF THE CWA SHOULD SEE A PERIOD OF LIGHT SNOW OR
FLURRIES. HIGH RES MODELS REALLY PICKING UP ON THE DRIER
AIR FOR THE CENTRAL CWA AND LIMITING QPF...SO WILL CONTINUE THAT
IDEA IN THE POPS AND SNOW AMOUNTS. BEST CHANCES FOR OVER AN INCH
WILL BE OVER THE WESTERN CWA AND EAST OF MUNISING.
BEHIND THIS FRONT...A PERIOD OF LAKE EFFECT IS EXPECTED WEDNESDAY
AFTERNOON INTO THURSDAY NIGHT. COLD AIR QUICKLY SURGES IN FROM THE
NORTHWEST ON WEDNESDAY AFTERNOON AND EVENING ACROSS THE
CWA...REACHING -25C BY 12Z THURSDAY. THIS PUTS MUCH OF THE CLOUD
LAYER ABOVE THE DGZ AND SHOULD LEAD TO LOWER SNOW RATIOS. WITH THAT
BEING SAID...STILL LOOKS LIKE VERY HIGH LAKE INDUCED EQL
VALUES...AROUND 10KFT...AND CAPE VALUES AROUND 900 J/KG. THERE IS
VERY DRY AIR ABOVE THE ACTUAL INVERSION AROUND 5KFT...SO WONDERING
IF THAT COMBINED WITH THE LOWER SNOW RATIOS WILL KEEP SNOWFALL
AMOUNTS FROM BEING TOO HEAVY WEDNESDAY NIGHT INTO THURSDAY.
ONE OTHER TREND TO MENTION IS THE IDEA OF A SURFACE TROUGH
LINGERING OVER EASTERN LAKE SUPERIOR LATE WEDNESDAY NIGHT AND
POTENTIALLY DEVELOPING INTO A WEAK LOW ON THURSDAY. EVEN THE COARSE
MODELS ARE STARTING TO SHOW THIS...WHICH IF IT OCCURS...MAY HELP
FOCUS AN AREA OF CONVERGENCE IN EASTERN ALGER AND LUCE COUNTIES FOR
HEAVIER SNOW. HIGH PRESSURE RIDGE SLIDES SOUTH OF THE AREA THURSDAY
AFTERNOON INTO THURSDAY NIGHT...WHICH WILL LEAD TO BACKING WINDS
AHEAD OF THE NEXT CLIPPER THAT WILL AFFECT THE AREA ON FRIDAY. THIS
WILL LEAD TO DRIER AIR ALOFT AND WARMING H850 TEMPS...WHICH
STRENGTHENS THE INVERSION TO AROUND 6KFT WHILE ALSO PUSHING THE DGZ
BACK INTO THE CLOUD LAYER. IN ADDITION...WITH THE WINDS LIKELY
BACKING MORE TO THE WEST...EXPECT THE LAKE EFFECT TO BE CONFINED TO
THE WESTERN CWA AND RIGHT ALONG THE SHORELINE OVER THE EAST IN THE
EVENING.
LOOKING AT CIPS ANALOG GUIDANCE...THE BEST FIT FOR THIS PERIOD IS
THE DECEMBER 10-11 1980 PERIOD...WHICH CORRELATES VERY WELL IN
H850 TEMPS ALTHOUGH THE SURFACE HIGH TO THE SOUTHWEST MAY BE
SLIGHTLY CLOSER TO THE CWA. 72-HR SNOWFALL AMOUNTS DURING THAT
PERIOD WERE GENERALLY IN THE 4-12 INCH RANGE...WHICH LENDS
CONFIDENCE TO THE GOING FORECAST THOUGHTS. IN ADDITION...LOOKING AT
PROBABILITIES FROM THE TOP 15 ANALOGS THEY SHOW A SIMILAR IDEA
FOR SNOW AMOUNTS...EVEN THOUGH THE MEAN H850 TEMPS ARE A LITTLE
WARMER THAN CURRENTLY EXPECTED. WILL CONTINUE TO MENTION MODERATE
SNOW IN THE HWO...SINCE SOME LOCATIONS WILL PROBABLY NEED LAKE
EFFECT SNOW ADVISORIES...DUE TO ADDITIONAL REDUCED VISIBILITIES WITH
THE FINER SNOWFLAKES AND SOME BLOWING SNOW. IN ADDITION...LOOKING AT
COOP TEMPERATURE OBSERVATIONS DURING THAT 1980 EVENING...THE GOING
IDEA OF HIGHS OF 10-15 AND LOWS AROUND ZERO LOOKS GOOD.
MODELS CONTINUE TO HAVE SUBTLE DIFFERENCES WITH THE CLIPPER
SYSTEM...BUT THE OVERALL IDEA OF IT TRAVERSING THE CWA SEEMS
REASONABLE FOR FRIDAY. SNOW LOOKS TO ARRIVE DURING THE LATER PART
OF THURSDAY NIGHT AND INTO FRIDAY...UNDER THE STRONG H850 WAA. AT
THIS POINT...LOOKS LIKE ANOTHER DUSTING OF AROUND AN INCH OF SNOW.
THE WARMING SOUTHWEST FLOW WILL ALSO PUSH HIGHS 10-15 DEGREES
WARMER THAN THURSDAY.
AFTER THAT...CONFIDENCE QUICKLY DROPS IN THE FORECAST...AS THERE
ARE VARYING TIMES AT WHICH THE NEXT STRONGER SHORTWAVE ARRIVES.
00Z GFS IS FASTER AND ARRIVES EARLY SATURDAY...WHILE THE 00Z
ECMWF/GEM HAVE IT ARRIVING SATURDAY AFTERNOON. FOR THIS TIME OF THE
YEAR...THESE DIFFERENCES MAKE A HUGE DIFFERENCES FOR THE FORECAST
DUE TO WIND FIELDS...H850 TEMPS...AND POTENTIAL FOR LAKE EFFECT.
WILL JUST GO WITH A GENERAL CHANCE POPS FOR THE ENTIRE AREA...WITH
THE HIGHEST VALUES NEAR LAKE SUPERIOR.
ONCE THIS WAVE DEPARTS...LOOKS TO BE ANOTHER PERIOD OF MULTI-BAND
LAKE EFFECT FOR THE NORTHWEST WIND LAKE EFFECT AREAS SUNDAY INTO
MONDAY. AFTER BECOMING DISRUPTED SOME WITH THE LAST SHORTWAVE...THE
UPPER TROUGH WILL AGAIN REESTABLISH ITSELF OVER THE GREAT LAKES
THROUGH THE FIRST PART OF NEXT WEEK. H850 TEMPS WILL AGAIN BE AROUND
-25C AND LEAD TO PERIODS OF MODERATE LAKE EFFECT SNOW. WILL BUMP
POPS UP BASED OFF LOCAL LAKE EFFECT CLIMATOLOGY GRIDS TO HIGH
CHANCE OR LOW LIKELY VALUES FOR NORTHWEST WIND LOCATIONS.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z TUESDAY NIGHT)
ISSUED AT 1209 AM EST TUE JAN 15 2013
CMX...EXPECT PREDOMINANT MVFR/OCNL IFR CONDITIONS EARLY IN THE FCST
PERIOD UNDER ONGOING LAKE EFFECT SHSN. AS THE LLVL FLOW BACKS MORE
TO THE SW EARLY THIS MRNG...EXPECT THE SHSN TO SHIFT TO THE N OF THE
SITE AND CONDITIONS TO TRANSITION TO PRIMARILY VFR. ANOTHER
DISTURBANCE WL BRING MORE CLDS AND PSBLY MORE MVFR CIGS THRU THE
REST OF THE MRNG PER UPSTREAM OBS IN MN. CIGS WL THEN RETURN TO VFR
FOLLOWING THE PASSAGE OF THIS DISTURBANCE BY AFTN. AS A STRONGER SW
GRADIENT FLOW DEVELOPS THIS AFTN...THERE MAY BE SOME GUSTY
WINDS...WHICH WL TRANSITION TO LLWS TNGT WITH NOCTURNAL COOLING
LIMITING MIXING TO THE SFC. SINCE THIS SW FLOW WL BE DRY...
CONDITIONS WL REMAIN VFR.
IWD...AN APRCHG DISTURBANCE WL BRING VFR CIGS TRANSITIONING TO MVFR
BY 12Z PER UPSTREAM OBS IN MN. CIGS WL THEN RETURN TO VFR FOLLOWING
THE PASSAGE OF THIS DISTURBANCE BY AFTN. AS A STRONGER SW GRADIENT
FLOW DEVELOPS THIS AFTN...THERE MAY BE SOME GUSTY WINDS...WHICH WL
TRANSITION TO LLWS TNGT WITH NOCTURNAL COOLING LIMITING MIXING TO
THE SFC. SINCE THIS SW FLOW WL BE DRY...CONDITIONS WL REMAIN VFR.
SAW...EXPECT VFR CONDITIONS THRU SUNRISE. ALTHOUGH AN APRCHG
DISTURBANCE MIGHT BRING MORE CLDS LATER THIS MRNG...SUSPECT CIGS WL
REMAIN IN THE VFR RANGE. AS A STRONGER SW GRADIENT FLOW DEVELOPS
THIS AFTN...THERE MAY BE SOME GUSTY WINDS...WHICH WL TRANSITION TO
LLWS TNGT WITH NOCTURNAL COOLING LIMITING MIXING TO THE SFC. SINCE
THIS SW FLOW WL BE DRY...CONDITIONS WL REMAIN VFR.
&&
.MARINE...(FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 500 AM EST TUE JAN 15 2013
SOUTHWEST WINDS WILL INCREASE THIS AFTERNOON AND TONIGHT AHEAD OF
AN APPROACHING COLD FRONT. THIS WILL PRODUCE GALES TO 35-40KTS AND
WILL CONTINUE THE GALE WARNING FOR TONIGHT INTO WEDNESDAY. WINDS
WILL SHIFT TO THE WEST AND THEN NORTHWEST AND GUST TO 40KTS DURING
THE DAY WEDNESDAY BEHIND THE FRONT. NORTHWEST WINDS OF 15-30KTS
WILL CONTINUE WEDNESDAY NIGHT INTO THURSDAY...WITH OCCASIONAL GALE
FORCE GUSTS TO 35KTS. A SERIES OF CLIPPER SYSTEMS ARE EXPECTED TO
MOVE THROUGH ON FRIDAY AND AGAIN ON SATURDAY. THIS WILL DISRUPT THE
WINDS SOME DURING THOSE PERIODS...WITH NORTH-NORTHWEST WINDS TO
30KTS AGAIN EXPECTED SATURDAY NIGHT.
FINALLY...HEAVY FREEZING SPRAY IS EXPECTED WEDNESDAY NIGHT INTO
THURSDAY EVENING OVER MUCH OF LAKE SUPERIOR.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
LAKE EFFECT SNOW WARNING UNTIL 7 AM EST THIS MORNING FOR MIZ001-
003.
LAKE SUPERIOR...
GALE WARNING FROM 7 PM THIS EVENING TO 7 PM EST WEDNESDAY FOR
LSZ264>267.
GALE WARNING FROM 7 PM EST /6 PM CST/ THIS EVENING TO 1 PM EST
/NOON CST/ WEDNESDAY FOR LSZ162-263.
GALE WARNING FROM 1 AM TO 7 PM EST WEDNESDAY FOR LSZ244-245-
249>251.
GALE WARNING FROM 1 PM TO 7 PM EST WEDNESDAY FOR LSZ248.
GALE WARNING FROM 1 AM EST /MIDNIGHT CST/ TO 1 PM EST /NOON CST/
WEDNESDAY FOR LSZ240>243.
LAKE MICHIGAN...
GALE WARNING FROM 4 AM TO 1 PM EST WEDNESDAY FOR LMZ221-248-250.
&&
$$
SHORT TERM...JLB
LONG TERM...SRF
AVIATION...KC
MARINE...SRF
AREA FORECAST DISCUSSION
NWS HASTINGS NE
1229 AM CST TUE JAN 15 2013
.AVIATION...06Z KGRI TAF. SOME MVFR STRATUS WITH A FEW FLURRIES IS
CURRENTLY TO THE WEST/NORTHWEST OF THE TERMINAL NEAR LBF AND
JUST NORTH OF ODX. THIS CONTINUES TO STREAM AND EXPAND
NORTHEASTWARD WITHOUT MUCH EASTWARD PROGRESSION TOWARD KGRI. SOME
SCATTERED VFR SKY COVER IS DETECTED ON SATELLITE EAST OF THE MAIN
AREA OF STRATUS...BUT THE STRATUS SHOULD REMAIN WEST OF THE
TERMINAL OVERNIGHT BEFORE MIXING OUT DURING THE DAY ON TUESDAY.
WIND SHOULD REMAIN RELATIVELY LIGHT WITH ANY REDUCED VISIBILITY
EXPECTED TO REMAIN WITH LIGHT SNOW/FLURRY ACTIVITY ASSOCIATED WITH
THE STRATUS TO THE WEST/NORTHWEST.
&&
.PREV DISCUSSION... /ISSUED 910 PM CST MON JAN 14 2013/
UPDATE...AS OF 03Z WATER VAPOR IMAGERY INDICATES A LONGWAVE
TROUGH ACROSS THE CENTRAL CONUS. A WEAK RIDGE OF HIGH PRESSURE IS
ALSO NOTED AT THE SURFACE OVER PORTIONS OF THE MISSOURI VALLEY.
LOW LEVEL RETURN FLOW IS BEING OBSERVED OVER PORTIONS OF WESTERN
KANSAS...AS WELL AS PORTIONS OF WESTERN AND CENTRAL NEBRASKA AND
AS A RESULT...WEAK ISENTROPIC UPGLIDE AND SATURATION ALONG THE
275-280K SURFACES PERSIST ACROSS PORTIONS OF THE REGION. THIS
ISENTROPIC UPGLIDE...WORKING IN CONCERT WITH WEAK MID LEVEL
THERMAL ADVECTION AHEAD OF THE LONGWAVE TROUGH...IS PROMOTING A
WEAK BAND OF LIGHT SNOW OVER PORTIONS OF NORTHWEST KANSAS AND
SOUTHWEST NEBRASKA...WITH FLURRY ACTIVITY NOTED ON KUEX DATA AND
OBSERVED AT KHDE WITH IN THE PAST HOUR. SHORT TERM GUIDANCE FROM
THE RAP AND NAM SUGGEST THE ISENTROPIC UPGLIDE SHOULD DIMINISH
THROUGH THE NEXT SIX HOURS OR SO BUT UNTIL THAT TIME...OCCASIONAL
FLURRY ACTIVITY CANNOT BE RULED OUT ACROSS THE WEST/NORTHWEST HALF
OF OUR CWA. WENT AHEAD AND INTRODUCED FLURRY WORDING TO THE
FORECAST FOR THESE LOCATIONS FOR TONIGHT AS A RESULT. THE
REMAINDER OF THE FORECAST REMAINS IN GREAT SHAPE...WITH ONLY SOME
MINOR TWEAKS MADE TO HOURLY TEMPERATURE...DEWPOINT...AND WIND
GRIDS TO BETTER REFLECT CURRENT OBSERVATIONS.
PREV DISCUSSION... /ISSUED 358 PM CST MON JAN 14 2013/
SHORT TERM...TONIGHT THROUGH TUESDAY. COLD AND DRY WEATHER WILL
CONTINUE WITH BELOW NORMAL TEMPERATURES...ALTHOUGH TUESDAY WILL BE
AT LEAST SOMEWHAT WARMER THAN TODAY.
TONIGHT...THE UPPER LEVEL TROUGH AXIS WILL SLIDE INTO OUR FORECAST
AREA AND SOME MID LEVEL CLOUDS ARE EXPECTED. THIS SHOULD KEEP LOW
TEMPERATURES A FEW DEGREES WARMER THAN LAST NIGHT. HOWEVER...THE
CLOUDS MAY BEGIN TO CLEAR ACROSS OUR NORTHWEST PRIOR TO SUNRISE
ALLOWING FOR GREATER RADIATIONAL COOLING. THEREFORE...EXPECT THE
COLDEST READINGS TO LIKELY RUN FROM AROUND ORD TO GOTHENBURG.
TOMORROW...THE LOW LEVEL WIND FIELD WILL BE WESTERLY ALLOWING WARMER
AIR TO SLOWLY WORK BACK INTO THE PLAINS. IN ADDITION...SUNNY TO
MOSTLY SUNNY SKIES ARE EXPECTED. THE STRIPE OF SNOW COVER ACROSS THE
CENTER OF OUR CWA WILL CONTINUE TO KEEP HIGH TEMPERATURES SEVERAL
DEGREES COOLER OVER SNOW COVERED AREAS THAN OVER SNOW FREE AREAS.
WILL CALL FOR ABOVE FREEZING HIGH TEMPERATURES OVER SNOW FREE
AREAS...WITH HIGHS A FEW DEGREES BELOW FREEZING OVER OUR SNOW
COVERED AREAS.
LONG TERM...(TUESDAY NIGHT THROUGH MONDAY)
THE MAIN STORY: A STRING OF VERY NICE/MILD DAYS BEGINS WED AS THE
CURRENT COLD SNAP EASES...GIVING US A BREAK BEFORE THE "POTENTIALLY"
COLDEST AIR SO FAR THIS SEASON EARLY NEXT WEEK.
PATTERN: THE LONG-WAVE FLOW YOU SEE WED /WRN N AMERICA RIDGE AND AN
ERN TROF/ WILL BE WITH US FOR THE NEXT 10 DAYS. THE GFS ENSEMBLE HAS
A STRONG SIGNAL FOR A +PNA PATTERN THRU THIS PERIOD...PEAKING ON THE
21ST. THIS MEANS THE ERN USA WILL BE DEALING WITH FRIGID ARCTIC COLD
DELIVERED BY A TRAIN OF ALBERTA CLIPPERS. FOR NOW NW FLOW WILL LOCK
THE ARCTIC FRONT JUST NE OF THE FCST AREA. AND WHILE WE WILL BENEFIT
FROM DOWNSLOPE WARMING IN THE WARM SECTOR OF THESE CLIPPERS...
BELIEVE WE WILL HAVE TO DEAL WITH SPELL OF BITTER ARCTIC COLD DURING
THE NEXT 10 DAYS. MODELS HAVE BEEN HINTING THAT THE WRN FRINGE OF
THIS AIR MASS BACKS INTO CNTRL PLAINS NEXT SUN-MON. WATCH THE SWD
PROGRESSION WITH EACH CLIPPER! THE GFS ENSEMBLE MEAN ALREADY HAS -1
STANDARD DEVIATION TEMPS AT H8 IN THAT TIMEFRAME AND THAT/S WITH
-15C. 00Z EC ENSEMBLE MEAN HAS -12C BUT THAT/S WITH A LOT GREATER
MEMBERSHIP AND MORE AVERAGING. THE 06Z/12Z DETERMINISTIC GFS CYCLES
HAVE -17 OR -18C WHICH WOULD SUPPORT HIGHS IN THE SINGLE DIGITS OVER
S-CNTRL NEB. THIS WITH HIGH PRES NEAR OR IN EXCESS OF 1040 MB.
A STEADY-STATE PATTERN OFFERS ABOVE AVERAGE FCST CONFIDENCE.
BOTTOM LINE...TEMPS WILL AVERAGE ABOVE NORMAL /OR MUCH ABOVE NORMAL
FOR AREAS WITH NO SNOW COVER/ THRU SAT THEN TURNING MUCH BELOW
NORMAL SUN-MON THRU THE MIDDLE OF NEXT WEEK. DRIER THAN NORMAL WITH
MOST PLACES PROBABLY NOT EVEN REGISTERING A TRACE OF PRECIP OVER THE
NEXT 10 DAYS.
HAZARDS: 1) A WARM FRONTAL PASSAGE COULD THREATEN A BIT OF LIGHT SN
OR FRZG DRIZZLE TUE NGT OVER OUR S-CNTRL NEB COUNTIES.
2) THERE IS A CHANCE OF DANGEROUSLY LOW WIND CHILLS EARLY
NEXT WEEK. TOO EARLY TO TELL ON WIND SPEEDS BUT
SOMETHING TO WATCH.
UPCOMING PCPN OPPORTUNITIES: NOTHING SUBSTANTIAL.
THE DAILY DETAILS...
ALL INITIALIZED LOW TEMPS WERE REPLACED WITH ITS BIAS CORRECTED
COUNTERPART UNLESS OTHERWISE NOTED.
TUE NGT: INCREASING CLOUDS. MILD WITH A BREEZY SW WIND SHIFTING TO
THE W. WARM FRONTAL PASSAGE. SOUNDINGS THREATEN A TOUCH OF LIGHT SN
OR FRZG DRIZZLE. IT/S NOT IN THE FCST BUT SOMETHING TO WATCH. TEMPS
WILL DROP INITIALLY WITH SUNSET THEN TEMPS HOLDING STEADY OR SLOWLY
RISING.
WED: BECOMING M/SUNNY. CLIPPER RACES ACROSS SRN CANADA. TEMPS ARE
BIAS CORRECTED MEX MOS. THE NAM HAS TOO MUCH CONTAMINATION FROM ITS
MODELED SNOW COVER. BUT DID I GO WARM ENOUGH IN THE NO/LOW SNOW
COVER AREAS? WE/LL BE STARTING FROM VERY MILD MID-UPPER 20S AND SOME
2M TEMP GUIDANCE IS SUGGESTING LOW 50S OUTSIDE AREAS WITH REMAINING
CRUSTY SNOW COVER.
THU: HIGH PRES DRIFTS THRU IN THE MRNG WITH SW WINDS DEVELOPING.
M/SUNNY. HAVE TEMPS FAIRLY CLOSE TO WED/S HIGHS. USED BIAS CORRECTED
MAV MOS AGAIN. WITH RETURN FLOW DELAYED INTO THE AFTN...FCST TEMPS
COULD END UP 2-3F TOO WARM.
FRI: ANOTHER VERY NICE DAY IN THE WARM SECTOR OF ANOTHER CLIPPER
ROTATING THRU THE GREAT LAKES. TEMPS ARE BIAS CORRECTED MEX MOS.
COULD SEE ORD AND STOCKTON/OSBORNE/BELOIT FLIRT WITH 50F!
SAT: PROBABLY ANOTHER PLEASANT DAY BUT WITH AN ARCTIC COLD FRONTAL
PASSAGE. UNCERTAINTY IN TEMPS AS MODELS STRUGGLE WITH EXACT TIMING/
LOCATION OF THE FRONT.
WIND: WE PROBABLY HAVE TO DEAL WITH A PERIOD OF BLUSTERY N WINDS
BEHIND THE FRONT. NOT SURE ON THE TIMING.
SUN-MON: AFTER COORDINATING WITH SURROUNDING OFFICES...ALL DAYTIME/
NIGHTTIME TEMPS WERE LOWERED TO THE WEIGHTED CONSENSUS OF THE 3
BEST-VERIFYING TEMP GUIDES.
SUN: COLDER BUT NOT UNBEARABLE.
SUN NGT OR MON: THE ARCTIC FLOOD-GATES OPEN WITH A BITTER 1050 MB
HIGH SLIDING DOWN THE FRONT RANGE.
MON: BITTERLY COLD AND WE NEED TO KEEP THE DOOR OPEN FOR SINGLE
DIGITS HIGH TEMPS! ESPECIALLY OVER OUR NEB COUNTIES. EVEN WITH THE
MORE CONSERVATIVE GFS AND 00Z EC...IF WE END UP CLOUDY IT WILL BE A
SLAM-DUNK. WATCH FOR LOW CLOUDS TO GET TRAPPED UNDER THE FRONTAL
INVERSION. THE 12Z EC CAME IN AND IS PROBABLY THE WORST CASE
SCENARIO...WITH -24C DOWN TO GRI AT 00Z/TUE.
EVEN THO WE/VE LOWERED TEMPS...WE STILL COULD BUST ANOTHER 5-10F TOO
HIGH.
&&
.GID WATCHES/WARNINGS/ADVISORIES...
NE...NONE.
KS...NONE.
&&
$$
AVIATION...HEINLEIN
910PM UPDATE...BRYANT
SHORT TERM...WESELY
LONG TERM...HALBLAUB
AREA FORECAST DISCUSSION...UPDATED
NWS NORTH PLATTE NE
1119 PM CST MON JAN 14 2013
.UPDATE...
.AVIATION...
MVFR/LOCAL IFR IN SNOW HAS DEVELOPED FROM KIML TO KLBF. THIS AREA
IS DRIFTING EAST AND IS EXPECTED TO CONTINUE MOVING VERY SLOWLY
EAST OVERNIGHT.
MVFR CIGS SHOULD DEVELOP TUESDAY EVENING ACROSS NRN NEB AS AN
UPPER LEVEL DISTURBANCE DROPS SOUTH THROUGH THE NRN HIGH PLAINS.
LIGHT SNOW MAY DEVELOP IN SOME AREAS.
OTHERWISE VFR ALL AREAS OVERNIGHT AND TUESDAY.
.PREV DISCUSSION... /ISSUED 745 PM CST MON JAN 14 2013/
UPDATE...
DISCUSSION...
WE ARE FAST APPROACHING FCST LOWS ACROSS THE NORTH WHERE SKIES ARE
CLEAR. SO A NEW MIN TEMPERATURE FCST IS OUT. THE REST OF THE FCST
IS ON TRACK.
PREV DISCUSSION... /ISSUED 531 PM CST MON JAN 14 2013/
UPDATE...
AVIATION...
VFR IS EXPECTED ALL AREAS TONIGHT AND TUESDAY.
A WEAK UPPER LEVEL DISTURBANCE ACROSS SWRN NEB WILL SPREAD LIGHT
SNOW THROUGH THE EVENING HOURS. IT IS NOT CLEAR MVFR WILL COVER
THIS AREA. LOCAL MVFR COULD DEVELOP AS THIS AREA OF SNOW MOVES
THROUGH. ANOTHER AREA TO WATCH WOULD BE NORTHWEST NEBRASKA LATE
TOMORROW AFTERNOON. AN UPPER LEVEL DISTURBANCE ACROSS THE NRN HIGH
PLAINS WILL BE MOVING SOUTHEAST TOWARD NORTHWEST NEBRASKA LATE IN
THE AFTERNOON. THIS DISTURBANCE HAS THE POTENTIAL TO PRODUCE MVFR
CIGS. OTHERWISE VFR WILL PREVAIL.
PREV DISCUSSION... /ISSUED 426 PM CST MON JAN 14 2013/
UPDATE...
DISCUSSION...
QUICK UPDATE FOR SOUTHWEST NEBRASKA. THE RUC13 SHOWS AND AREA OF
LIGHT SNOW ON THE 285K INSENTROPIC SFC MOVING EAST THIS EVENING.
THE NEW FORECAST SLOWS THIS DOWN ABOUT 3 HOURS AND RAISES THE POP
TO 50 PERCENT. LESS THAN AN INCH ACCUMULATION IS EXPECTED
ALTHOUGH THE RUC SHOWS 3 INCHES. THE RUC IS OFTEN TOO WET. REST OF
THE FORECAST IS GOOD.
PREV DISCUSSION... /ISSUED 245 PM CST MON JAN 14 2013/
SYNOPSIS...
IN THE UPPER LEVELS...THE LARGE SCALE CYCLONIC FLOW CONTINUES
OVER A LARGE PART OF THE CENTRAL AND WESTERN U.S. RUNNING A 24 HOUR
LOOP OF THE IMAGERY...ONE CAN SEE THE DIGGING AND NARROWING OF THE
TROUGH. ANALYSIS OF THE 20Z SURFACE DATA REVEALED A WARM FRONT
DEVELOPING ACROSS EASTERN MONTANA AND EASTERN WYOMING.
SHORT TERM...TONIGHT THROUGH TUESDAY NIGHT.
A LOOK AT THE 280-290K LAYER INDICATES SOME WEAK ISENTROPIC LIFT
CONTINUING INTO THIS EVENING IN EXTREME SOUTHWEST NEBRASKA.
HOWEVER...VERY LITTLE MOISTURE AND ACCUMULATIONS WILL BE HALF AN
INCH OR LESS.
FOR TUESDAY...A WARM FRONT IS EXPECTED INTO WESTERN NEBRASKA BY
EARLY EVENING. AGAIN...IN THE 280-290K LAYER...ISENTROPIC UPGLIDE IS
LIKELY TO PRODUCE SOME CLOUDINESS AND POSSIBLY SOME LIGHT SNOW IN
THE EVENING AND LIGHT FREEZING DRIZZLE LATE TUESDAY NIGHT AND VERY
EARLY WEDNESDAY.
MEDIUM RANGE/EXTENDED...WEDNESDAY THROUGH SUNDAY.
DRY AND MUCH WARMER WEATHER CAN BE EXPECTED WEDNESDAY THROUGH
FRIDAY IN THE AFTERMATH OF THE WARM FRONT.
MUCH COLDER WEATHER IS EXPECTED AGAIN AS A BACK-DOOR FRONT COMES
ACROSS SATURDAY NIGHT AND SUNDAY. THE FRONT STALLS ALONG THE EASTERN
SLOPE OF THE ROCKIES AND SOUTHWEST FLOW WILL PRODUCE ISENTROPIC LIFT
AND COULD GIVE SOME POTENTIAL FOR WIDESPREAD SNOW MONDAY AS THE
SYSTEM MAKES ITS WAY BACK TO THE EAST-NORTHEAST. AT THAT RANGE...
THE UNCERTAINTY IS VERY HIGH REGARDING AMOUNTS AND INTENSITY OF
PRECIPITATION.
AVIATION...
FOR THE 18Z TAF FORECAST CYCLE...GENERAL VFR EXPECTED TODAY
ACROSS MOST AREA TERMINALS. THE EXCEPTION BEING ACROSS FAR
SOUTHWEST NEBRASKA TODAY...POSSIBLY AFFECTING THE KOGA AND KIML
TERMINALS WHERE SCATTERED LIGHT SNOW MAY BRIEFLY REDUCE VISIBILITIES
INTO MVFR. MODEL GUIDANCE HAS THE REMAINING LIGHT SNOW DISSIPATING
LATER THIS AFTERNOON...IF NOT ALREADY SO...THEREAFTER DRIER AIR
ALOFT WILL WORK BACK ACROSS THE REGION...WITH NO VISIBILITY OR
CEILING RESTRICTIONS ANTICIPATED. FOR THE OVERNIGHT...NAM SHORT
TERM GUIDANCE HINTS AT REDUCED VISIBILITY /DOWN TO 3SM/ AT KLBF
AFTER 06Z WITH THE FORMATION OF LOW FOG. FEEL THAT THE SOLUTION IS
OVERLY AMBITIOUS WITH THE REMAINING LOW LEVEL MOISTURE...SO WILL NOT
INCLUDE A MENTION OF MVFR VISIBILITY IN THE OFFICIAL TAF FORECAST
NOW. OTHERWISE BROAD SURFACE HIGH PRESSURE WILL KEEP WIND SPEEDS
RELATIVELY LIGHT AND VARIABLE FOR ALL TERMINALS.
&&
.LBF WATCHES/WARNINGS/ADVISORIES...NONE.
&&
$$
SHORT TERM/EXTENDED...BROOKS
AVIATION...CDC
AREA FORECAST DISCUSSION
NWS WILMINGTON OH
437 AM EST TUE JAN 15 2013
.SYNOPSIS...
LOW PRESSURE WILL TRACK ACROSS THE SOUTHERN APPALACHIANS TONIGHT
...BRINGING A WINTRY MIX OF PRECIPITATION TO SOUTHERN PORTIONS OF
THE OHIO VALLEY. HIGH PRESSURE WILL THEN BUILD EAST ACROSS THE
AREA LATE THIS WEEK.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
THE FORECAST AREA WILL START OFF THE DAY BEING LODGED BETWEEN
SURFACE RIDGING TO OUR NORTHEAST AND A NEARLY STATIONARY FRONT
DRAPED ACROSS THE APPALACHIANS. A BAND OF LOW CLOUDS ASSOCIATED
WITH COLD ADVECTION WILL LIKELY REMAINED ANCHORED ACROSS OUR NORTH
FOR MUCH OF THE DAY. ACROSS THE SOUTH...CLOUD COVER WILL ALSO
REMAIN IN PLACE AS MOISTURE ALOFT WILL CONTINUE TO STREAM
NORTHEASTWARD BEHIND THE FRONTAL BOUNDARY. IN BETWEEN THERE WILL
BE A SUNNY START TO THE DAY. EVENTUALLY THE COMBINATION OF CLOUD
COVER INCHING ITS WAY SOUTHWARD...AND UPPER LEVEL MOISTURE PUSHING
IN FROM THE SOUTH...WILL RESULT IN CLOUDY CONDITIONS AREA WIDE BY
LATE THIS AFTERNOON. WHERE CLOUD COVER MAY PERSIST ACROSS THE
NORTH...TEMPERATURES COULD STRUGGLE TO REACH THE LOWER 30S. ACROSS
THE REST OF THE AREA EXPECT TEMPERATURES TO REACH THE MIDDLE 30S
THIS AFTERNOON.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH FRIDAY/...
A POSITIVELY TILTED TROUGH EXTENDING FROM THE GREAT LAKES
SOUTHWESTWARD TO NEW MEXICO WILL DIG SOUTHEASTWARD AS A WEAK
SURFACE LOW LIFTS NORTHEASTWARD OUT OF THE WESTERN GULF OF MEXICO.
THIS LOW WILL TRACK ALONG THE STALLED OUT APPALACHIAN FRONTAL
BOUNDARY TONIGHT. AS THIS OCCURS...PRECIPITATION ON THE POLEWARD
SIDE OF THE LOW WILL SPREAD ACROSS SOUTHEASTERN PORTIONS OF THE
FORECAST AREA. THE MAJORITY OF FORECAST MODELS HAVE BEEN TRENDING
FARTHER NORTHWEST OVER THE PAST COUPLE OF RUNS WITH THE
PRECIPITATION TONIGHT. THIS FORECAST PACKAGE FOLLOWS SUIT AND
BRINGS CATEGORICAL POPS TO THE SOUTHEASTERN ZONES WITH A FAST
TAPER OFF TO CHANCE POPS JUST NORTH OF THE INTERSTATE 71 CORRIDOR.
THE MORE DIFFICULT PART OF TONIGHT`S FORECAST WILL BE PRECIPITATION
TYPE. SURFACE TEMPERATURES SHOULD STAY BELOW FREEZING FOR THE MOST
PART...EXCEPT THE ONSET IN THE EVENING...AS OUR AREA SHOULD REMAIN
COMPLETELY IN THE SURFACE COLD SECTOR AS THE LOW PASSES BY TO OUR
SOUTH. TEMPERATURES ALOFT HOWEVER WILL WARM ACROSS THE SOUTHEAST
AS SOME WARMER AIR NUDGES NORTHWARD AS THE LOW PASSES BY. THE
RESULT WILL LIKELY BE A WINTRY MIX OF PRECIPITATION ACROSS THE
SOUTHEAST...TRANSITIONING TO ALL SNOW TOWARD THE EDGE OF THE
PRECIPITATION SHIELD. DUE TO THE ONGOING UNCERTAINTY IN
PRECIPITATION TYPE AND THE FAIRLY LIGHT ACCUMULATIONS CURRENTLY
FORECAST...AM HOLDING OFF ON ANY WINTER WEATHER HEADLINES FOR NOW.
WILL HIGHLIGHT THE POTENTIAL FOR WINTER WEATHER HAZARDS IN THE HWO
FOR THIS PACKAGE.
THE LOW WILL SLIDE NORTHEAST OF THE OHIO VALLEY ON WEDNESDAY AND
PRECIPITATION WILL END AS ANOTHER LOW SWEEPS SOUTHEASTWARD ACROSS
THE NORTHERN GREAT LAKES. THE INCREASED PRESSURE GRADIENT
ASSOCIATED WITH THIS NORTHERN BRANCH LOW WILL BRING SOME GUSTY
WINDS TO THE AREA DURING THE DAY WEDNESDAY.
LOW LEVEL HIGH PRESSURE WILL SLOWLY BUILD FROM THE WEST ACROSS THE
AREA WEDNESDAY NIGHT THROUGH THURSDAY NIGHT AND WILL BE CENTERED
ACROSS THE REGION BY FRIDAY. TEMPERATURES ARE EXPECTED TO BE
SEASONABLE DURING THIS TIME PERIOD. ANOTHER LOW IS EXPECTED TO
SLIDE PAST OUR AREA TO THE SOUTH THURSDAY AND THURSDAY NIGHT.
HOWEVER...ENOUGH RIDGING SHOULD BE IN PLACE ACROSS OUR AREA TO KEEP
ANY PRECIPITATION TO OUR SOUTH.
&&
.LONG TERM /FRIDAY THROUGH MONDAY/...
ANOTHER SYSTEM DROPS INTO THE SUBTLE GREAT LAKES TROF ON
SATURDAY. MODELS DIFFER ON THE STRENGTH OF THIS SYSTEM. THE GFS IS
THE STRONGEST...WITH THE ECMWF AND CMC BEING WEAKER. TYPICALLY
THERE IS A WIDE RANGE OF SOLUTIONS IN A PATTERN LIKE THIS AS THE
MODELS STRUGGLE TO DECIPHER THESE WEAK DISTURBANCES CORRECTLY.
LEANED WITH THE CONSENSUS ECMWF/CMC SOLUTION...WHICH KEEPS
SATURDAY DRY. A COLD FRONT THEN SWINGS ACROSS THE FA
SUNDAY...ALLOWING ARCTIC AIR TO SPILL INTO THE FA. THIS SHOULD
KICK OFF A ROUND OF SHSN FOR SUNDAY AND MONDAY.
AS FOR TEMPERATURES...CAA ON THURSDAY WILL KEEP HIGHS IN THE LOWER
30S IN THE NW TO AROUND 40 IN THE EXTREME S. SOME WAA WILL BRING
WARMER AIR IN FOR FRIDAY AND SATURDAY. HIGHS FRIDAY WILL BE IN THE
UPPER 30S TO LOWER 40S...WITH 40S FOR HIGHS ON SATURDAY.
TEMPERATURES WILL TAKE A DOWN TURN ON WITH THE PASSAGE OF THE COLD
FRONT AS HIGHS WILL RANGE FROM THE MID 30S IN THE N TO AROUND 40S
IN NRN KY. ON MONDAY THEY WILL STRUGGLE TO RECOVER INTO THE MID 20
IN THE NW COUNTIES...WITH SOUTHERN LOCATIONS POSSIBLY MAKING THE
MID 30S.
&&
.AVIATION /09Z TUESDAY THROUGH SATURDAY/...
MVFR CIGS ARE HANGING TOUGH ACROSS THE REGION. ITS HARD TO TELL ON
THE IR SATELLITE IMAGES DUE TO SOME HIGHER CLOUDS...BUT THE LOWER
CLOUDS LOOK LIKE THEY MAY BE EXPANDING ACROSS PARTS OF SOUTHWEST
OHIO AND NORTHERN KENTUCKY. MEANWHILE...THE NORTHERN BAND OF LOWER
CLOUDS ALONG AND NORTH OF I-70 DOES APPEAR TO BE TRYING TO ERODE FROM
THE SOUTH. THIS WILL MAKE FOR A DIFFICULT CIG FORECAST THIS
MORNING. THE LATEST RAP 925 MB RH SEEMS TO HAVE A DECENT HANDLE ON
THE CURRENT LOW CLOUDS SO WILL TREND FORECAST IN THAT DIRECTION.
GIVEN NORTHERLY LOW LEVEL FLOW PERSISTING...NOT SURE HOW MUCH MORE
EROSION WE WILL SEE ON THE SOUTHERN EDGE OF THE NORTHERN BAND AND
WOULD NOT BE SURPRISED IF THIS EVEN STARTS TO EXPAND BACK DOWN
TOWARD THE SOUTH. WILL GO AHEAD AND ERROR ON THE PESSIMISTIC SIDE
AND GENERALLY ALLOW FOR MVFR CIGS THROUGH MID MORNING AT THE TAF
SITES. WILL THEN GO AHEAD AND ALLOW FOR THE MVFR CIGS TO DISSIPATE
THROUGH LATE MORNING (ALTHOUGH THE RAP IS HANGING ON TO THE LOW
LEVEL MOISTURE THROUGH THE DAY). FOCUS WILL THEN SHIFT TOWARD THE
SYSTEM WORKING UP FROM THE SOUTH LATER TODAY INTO TONIGHT. MODELS
HAVE BEEN TRENDING FARTHER NORTH WITH THIS SYSTEM. RIGHT NOW THE
I-71 CORRIDOR APPEARS TO BE RIGHT ON THE EDGE OF ANY PCPN SO WILL
KEEP THE TAFS DRY AT THIS POINT AND JUST ALLOW FOR SOME LOWERING
CIGS THROUGH THE LAST PART OF THE PERIOD.
OUTLOOK...NO SIGNIFICANT WEATHER IS EXPECTED.
&&
.ILN WATCHES/WARNINGS/ADVISORIES...
OH...NONE.
KY...NONE.
IN...NONE.
&&
$$
SYNOPSIS...LATTO
NEAR TERM...LATTO
SHORT TERM...LATTO
LONG TERM...SITES
AVIATION...JGL
AREA FORECAST DISCUSSION
NWS WILMINGTON OH
1249 AM EST TUE JAN 15 2013
.SYNOPSIS...
LOW PRESSURE WILL TRACK TOWARDS THE SOUTHERN APPALACHIANS OVER THE
NEXT DAY OR TWO...LEADING TO INCREASED MOISTURE IN KENTUCKY AND
WEST VIRGINIA. HIGH PRESSURE IN INDIANA AND NORTHWEST OHIO WILL
KEEP THIS MOISTURE ALONG AND SOUTH OF THE OHIO RIVER TONIGHT AND
TUESDAY NIGHT. A WEAK COLD FRONT WILL CROSS THE NORTHERN OHIO
VALLEY ON THURSDAY.
&&
.NEAR TERM /UNTIL 6 AM THIS MORNING/...
ECHOES HAVE PASSED OFF TO THE EAST OF THE FORECAST AREA. SO NO
THREAT OF PRECIPITATION THROUGH THE NIGHT. CLOUDS ARE STARTING TO
CLEAR FROM THE SOUTHWEST. APPEARS THAT THEY WILL HANG ON LONGEST
IN THE NORTHWEST COUNTIES AND ALSO IN THE FAR SOUTHEAST. FORECAST
LOW TEMPERATURES STILL LOOK ON TRACK.
&&
.SHORT TERM /6 AM THIS MORNING THROUGH WEDNESDAY NIGHT/...
HIGH PRESSURE IN THE MIDWEST NOSING INTO THE GREAT LAKES
AFFECTING NORTHERN OHIO VALLEY WILL BATTLE WITH THE INCREASED
MOISTURE TO THE SOUTHEAST ALONG THE APPALACHIANS AND WEAK SURFACE
LOW PRESSURE RIDING NORTHEAST FROM THE GULF STATES.
EXPECT CLOUDS TO THE SOUTHEAST AND A CHANCE FOR PRECIPITATION
TUESDAY NIGHT. THIS IS A COMBINATION OF THE NORTHEAST MOVING
SURFACE LOW IN THE WESTERN CAROLINAS...AND AN UPPER LEVEL TROUGH
MOVING EAST ACROSS THE CENTRAL UNITED STATES. ANY TYPE OF DISJOINT
IN THE TWO WILL LEAD TO LESS THREAT FOR PRECIPITATION IN MY
SOUTHEAST COUNTIES...BUT THE FAVORABLE COMBINATION OF THE TWO
WORKING TOGETHER IS NOTED ON MOST MODEL SOLUTIONS THIS AFTERNOON.
MAXIMIZED THE CHANCE FOR RAIN OR A RAIN/SNOW MIX AT MIDNIGHT AND
QUICKLY RAMPED THE POPS DOWN BY DAYBREAK. THERMAL PROFILES AT
PORTSMOUTH FROM BUFKIT SUGGEST SOME TYPE OF A MIX ALTHOUGH THE
COLD POOL UNDERNEATH THE WARM LAYER ALOFT MAY NOT BE ENOUGH TO RE-
FREEZE THE RAIN FOR SLEET...AND THE SURFACE TEMPERATURES HOVERING
AT OR JUST BELOW FREEZING MAY NOT PRODUCE FREEZING RAIN. WITH SUCH
A NARROW CUTOFF TO THE NORTHWEST BETWEEN PRECIP AND DRY
CONDITIONS...AND SURFACE TEMPERATURES HOVERING RIGHT AROUND THE
FREEZING MARK...JUST WENT WITH WHAT THE THICKNESSES SUPPORTED AS
A WX TYPE IN THE SOUTHEAST...PRIMARILY RAIN/FREEZING RAIN THAT MAY
BE MIXED WITH SNOW.
TEMPERATURES WERE NOT SIGNIFICANTLY CHANGED IN ANY
PERIOD...LOWERED THEM 3-4 DEGREES TOMORROW NIGHT IN THE NORTHWEST
WITH THE THOUGHT OF GENERALLY CLEAR SKIES AND LIGHT WINDS.
&&
.LONG TERM /THURSDAY THROUGH MONDAY/...
SPLIT FLOW ACROSS THE U.S. AT THE BEGINNING OF THE PERIOD LEAVES
THE OHIO VALLEY BETWEEN SYSTEMS. THERE IS A SYSTEM IN THE NORTHERN
STREAM THAT WAS BRINGING PCPN TO THE GREAT LAKES. MEANWHILE A
CLOSED H5 LOW IS IN THE SRN PLAINS. THIS SECOND SYSTEM SLIDES E
THU NGT INTO FRI...KEEPING ITS PCPN OUT OF THE FA.
WEAK ENERGY KEEPS DROPPING ACROSS THE GREAT LAKES...WITH A SYSTEM
SWINGING THROUGH ON FRIDAY. ANOTHER SYSTEM DROPS INTO THE SUBTLE
GREAT LAKES TROF ON SATURDAY. MODELS DIFFER ON THE STRENGTH OF THIS
SYSTEM. THE GFS IS THE STRONGEST...WITH THE ECMWF AND CMC BEING
WEAKER. TYPICALLY THERE IS A WIDE RANGE OF SOLUTIONS IN A PATTERN
LIKE THIS AS THE MODELS STRUGGLE TO DECIPHER THESE WEAK DISTURBANCES
CORRECTLY. LEANED WITH THE CONSENSUS ECMWF/CMC SOLUTION...WHICH
KEEPS SATURDAY DRY. A COLD FRONT THEN SWINGS ACROSS THE FA
SUNDAY...ALLOWING ARCTIC AIR TO SPILL INTO THE FA. THIS SHOULD KICK
OFF A ROUND OF SHSN FOR SUNDAY AND MONDAY.
AS FOR TEMPERATURES...CAA ON THURSDAY WILL KEEP HIGHS IN THE LOWER
30S IN THE NW TO AROUND 40 IN THE EXTREME S. SOME WAA WILL BRING
WARMER AIR IN FOR FRIDAY AND SATURDAY. HIGHS FRIDAY WILL BE IN THE
UPPER 30S TO LOWER 40S...WITH 40S FOR HIGHS ON SATURDAY.
TEMPERATURES WILL TAKE A DOWN TURN ON WITH THE PASSAGE OF THE COLD
FRONT AS HIGHS WILL RANGE FROM THE MID 30S IN THE N TO AROUND 40S
IN NRN KY. ON MONDAY THEY WILL STRUGGLE TO RECOVER INTO THE MID 20
IN THE NW COUNTIES...WITH SOUTHERN LOCATIONS POSSIBLY MAKING THE
MID 30S.
&&
.AVIATION /06Z TUESDAY THROUGH SATURDAY/...
MVFR CIGS ARE HANGING TOUGH ACROSS THE REGION. ITS HARD TO TELL ON
THE IR SATELLITE IMAGES DUE TO SOME HIGHER CLOUDS...BUT THE LOWER
CLOUDS LOOK LIKE THEY MAY BE EXPANDING ACROSS PARTS OF SOUTHWEST
OHIO AND NORTHERN KENTUCKY. MEANWHILE...THE NORTHERN BAND OF LOWER
CLOUDS ALONG AND NORTH OF I-70 DOES APPEAR TO BE TRYING TO ERODE FROM
THE SOUTH. THIS WILL MAKE FOR A DIFFICULT CIG FORECAST THIS
MORNING. THE LATEST RAP 925 MB RH SEEMS TO HAVE A DECENT HANDLE ON
THE CURRENT LOW CLOUDS SO WILL TREND FORECAST IN THAT DIRECTION.
GIVEN NORTHERLY LOW LEVEL FLOW PERSISTING...NOT SURE HOW MUCH MORE
EROSION WE WILL SEE ON THE SOUTHERN EDGE OF THE NORTHERN BAND AND
WOULD NOT BE SURPRISED IF THIS EVEN STARTS TO EXPAND BACK DOWN
TOWARD THE SOUTH. WILL GO AHEAD AND ERROR ON THE PESSIMISTIC SIDE
AND GENERALLY ALLOW FOR MVFR CIGS THROUGH MID MORNING AT THE TAF
SITES. WILL THEN GO AHEAD AND ALLOW FOR THE MVFR CIGS TO DISSIPATE
THROUGH LATE MORNING (ALTHOUGH THE RAP IS HANGING ON TO THE LOW
LEVEL MOISTURE THROUGH THE DAY). FOCUS WILL THEN SHIFT TOWARD THE
SYSTEM WORKING UP FROM THE SOUTH LATER TODAY INTO TONIGHT. MODELS
HAVE BEEN TRENDING FARTHER NORTH WITH THIS SYSTEM. RIGHT NOW THE
I-71 CORRIDOR APPEARS TO BE RIGHT ON THE EDGE OF ANY PCPN SO WILL
KEEP THE TAFS DRY AT THIS POINT AND JUST ALLOW FOR SOME LOWERING
CIGS THROUGH THE LAST PART OF THE PERIOD.
OUTLOOK...NO SIGNIFICANT WEATHER IS EXPECTED.
&&
.ILN WATCHES/WARNINGS/ADVISORIES...
OH...NONE.
KY...NONE.
IN...NONE.
&&
$$
SYNOPSIS...FRANKS
NEAR TERM...
SHORT TERM...FRANKS
LONG TERM...SITES
AVIATION...JGL
AREA FORECAST DISCUSSION
NWS CLEVELAND OH
1146 PM EST MON JAN 14 2013
.SYNOPSIS...
HIGH PRESSURE WILL BUILD EAST ACROSS THE OHIO VALLEY AND LOWER
GREAT LAKES REGION TONIGHT INTO TUESDAY. TUESDAY NIGHT LOW
PRESSURE WILL ACROSS ACROSS THE NORTHERN GREAT LAKES REGION AND
DRAG A COLD FRONT ACROSS THE REGION LATE WEDNESDAY. A STRONGER
COLD FRONT WILL PASS THROUGH ON THURSDAY.
&&
.NEAR TERM /UNTIL 6 AM TUESDAY MORNING/...
A RIDGE IS BUILDING ACROSS THE AREA OVERNIGHT. THE QUESTION IS
WHAT WILL HAPPEN WITH THE CLOUDS. THE RUC/RAP MODEL KEEPS THE LOW
CLOUDS ACROSS THE ENTIRE FORECAST AREA ALL NIGHT. THE NAM MODEL
HAS THE LOW CLOUDS GONE BY MIDNIGHT...WHILE THE GFS MODEL SLOWLY
DECREASES THE CLOUDS OVERNIGHT. WENT CLOSER TO THE RAP MODEL AND
DECREASED THE CLOUDS OVER NORTHWEST OHIO AS PER THE SATELLITE
PHOTOS WHICH ARE SHOWING THE CLOUDS DECREASING BUT SOME CLOUDS ARE
REGENERATING. THE LOWS ARE TOUGH BECAUSE OF THE SKY COVER DILEMMA.
&&
.SHORT TERM /6 AM TUESDAY MORNING THROUGH THURSDAY NIGHT/...
HIGH PRESSURE CONTINUES TO BUILD ACROSS THE LOWER OHIO VALLEY
TUESDAY WITH MODELS SHOWING A SLIGHT INCREASE IN MOISTURE...MAINLY
HIGH LEVEL...ACROSS THE AREA TUESDAY EVENING. WILL CONTINUE WITH A
FAIR FORECAST THROUGH TUESDAY NIGHT. WEDNESDAY A COLD FRONT WILL
DROP ACROSS THE AREA AS THE PARENT LOW MOVES EAST ACROSS THE
CENTRAL AND NORTHERN GREAT LAKES INTO ONTARIO. MODELS BRING A
RATHER THIN SWATH OF LIMITED MOISTURE ACROSS THE AREA IN THE
AFTERNOON AS 850MB TEMPS DROP TO ABOUT -8 TO -9C EXTREME NORTHEAST
OHIO AND NWRN PA. GIVEN A 39 DEGREE LAKE -8C IS CERTAINLY NOT
EXTREME BUT COULD SEE A FEW SNOW SHOWERS DEVELOP DURING THE DAY
AND INTO THE NIGHT SO WILL HAVE SLIGHT CHANCE IN THE GRIDS FOR
WEDNESDAY...INCREASING TO CHANCE POPS WEDNESDAY NIGHT AS GFS TAKES
850MB TEMPS TO -13C TO -14C. THURSDAY THE GFS BEGINS WITH -14C
WITH THE NEXT COLD FRONT UPSTREAM ACROSS THE CENTRAL LAKES. WILL
INCREASE POPS TO LIKELY THURSDAY MORNING AS THE FRONT MOVES IN BUT
THEN BACK OFF TO CHANCE IN THE AFTERNOON AS HIGH PRESSURE BUILDS
ACROSS THE LOWER OHIO VALLEY AND DRIER AIR MOVES IN.
&&
.LONG TERM /FRIDAY THROUGH MONDAY/...
A BROAD TROUGH OVER NORTH AMERICA WILL DEEPEN OVER THE EASTERN
UNITED STATES DURING THE EXTENDED...ALLOWING AN ARCTIC AIRMASS TO
SETTLE SOUTH OVER THE REGION EARLY NEXT WEEK. LOW LEVEL BAROCLINIC ZONE
IN PLACE ACROSS THE GREAT LAKES REGION WILL LIFT NORTH ON FRIDAY AS
LOW PRESSURE APPROACHES FROM THE WEST. TEMPERATURES WILL BE AT OR
ABOVE NORMAL ON FRIDAY/SATURDAY BEFORE A SECONDARY CLIPPER SLIDES
THROUGH ON SATURDAY NIGHT AND PULLS A COLD FRONT SOUTH ACROSS THE
REGION. SCATTERED SNOW SHOWERS ARE EXPECTED ALONG THE FRONT...WITH
LAKE EFFECT INCREASING INTO SUNDAY AS THE 850MB TEMPERATURES FALL TO
-15 TO -18C AND INSTABILITY INCREASES OVER THE LAKE. A SECONDARY
WAVE WILL DIG THROUGH THE UPPER TROUGH ON MONDAY...FORCING AN EVEN
COLDER AIRMASS WITH 850MB TEMPS BELOW -20C OVER THE REGION FOR THE
EARLY PART OF NEXT WEEK.
&&
.AVIATION /06Z TUESDAY THROUGH SATURDAY/...
HIGH PRESSURE TO THE WEST WILL CONTINUE BUILDING INTO THE AREA
OVERNIGHT. SATELLITE SHOWING AREAS OF MVFR CLOUDS FROM ERI-CLE-MFD
AND FDY. THESE MVFR CLOUDS APPEAR TO BE ERODING FROM BOTH THE
SOUTHEAST AND NORTHWEST EARLY TONIGHT WITH VFR AT TOL...AS WELL AS
VFR AT CAK AND YNG. THINKING THAT THESE CLOUDS WILL CONTINUE TO
SLOWLY DISSIPATE THROUGH THE OVERNIGHT WITH MVFR SITES BECOMING
VFR BY DAYBREAK OR SHORTLY AFTER. VFR EXPECTED THROUGH TUESDAY
ACROSS SITES WITH LIGHT NORTHERLY-NE WINDS LESS THAN 10KT. SOME
MID TO HIGH CLOUDS BUILDING NORTHWARD OVER OHIO TUESDAY NIGHT.
OUTLOOK...NON-VFR POSSIBLE WEDNESDAY NIGHT AND THURSDAY IN NE
OHIO/NW PA.
&&
.MARINE...
PRESSURE GRADIENT SHOULD CONTINUE TO WEAKEN THROUGH THE EVENING
ALLOWING WINDS TO CONTINUE TO DIMINISH. WEAK HIGH PRESSURE RIDGE
OVER THE LAKE TUE SHOULD PROVIDE LIGHT AND VARIABLE WINDS THAT WILL
BECOME SW BY WED MORNING AHEAD OF A COLD FRONT THAT WILL CROSS
THE LAKE LATE WED NIGHT. WIND SPEEDS COULD BE CLOSE TO GALE FORCE
FOR A WHILE AROUND WED EVENING.
WINDS SHOULD TURN MORE NW THU AND CONTINUE TO DIMINISH THRU THU
NIGHT AS ANOTHER RIDGE OF HIGH PRESSURE SPREADS EAST OVER OHIO. THE
RIDGE SHOULD DROP SE FRI TO ALLOW THE FLOW TO TURN SW AGAIN AND
BEGIN TO INCREASE BY FRI NIGHT.
&&
.CLE WATCHES/WARNINGS/ADVISORIES...
OH...NONE.
PA...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS...TK
NEAR TERM...KIELTYKA
SHORT TERM...TK
LONG TERM...KEC
AVIATION...ABE
MARINE...ADAMS
AREA FORECAST DISCUSSION
NWS TULSA OK
343 AM CST TUE JAN 15 2013
.DISCUSSION...
LARGE SCALE TROUGHING THAT HAS REMAINED TO OUR WEST FOR SEVERAL
DAYS IS NOW IN THE PROCESS OF SLOWLY SHIFTING EASTWARD. YET
ANOTHER SMALL SCALE WAVE WILL EJECT AHEAD OF THE UPPER TROUGH
TODAY WITH PRECIP DEVELOPING ACROSS EASTERN TEXAS AND SPREADING
NORTHEASTWARD THROUGH THE AFTERNOON. FAR SE OK WILL BE THE ON THE
NORTHERN PERIPHERY OF THIS PRECIP SHIELD PER VARIOUS MODEL QPF
FIELDS...AND THIS ALIGNS FAIRLY WELL WITH THE ONGOING
STRENGTHENING OF MID LEVEL FRONTOGENETIC BAND IN LATEST RAP DATA.
MEASURABLE PRECIP CHANCES WILL BE LOW ACROSS FAR SE OK WITH ANY
PRECIP THAT DOES FALL EXPECTED TO BE A SLEET / SNOW MIX. ALL
PRECIP WILL HAVE SHIFTED WELL EAST OF THE FORECAST AREA BY THIS
AFTERNOON...WITH TEMPS CONTINUED BELOW NORMAL TODAY AND TONIGHT.
THE BASE OF THE UPPER TROUGH IS LIKELY TO DEVELOP A CLOSED LOW
THAT WILL TRACK ACROSS CENTRAL TEXAS ON WEDNESDAY...WHILE THE
LARGER TROUGH AXIS MAINTAINS A POSITIVE TILT KEEPING ASSOCIATED
PRECIP SHUNTED INTO THE SOUTHEASTERN STATES. WEDNESDAY WILL ALSO
MARK THE MORE NOTICEABLE WARM UP WITH TEMPS RETURNING TO NEAR MID
JANUARY NORMALS.
THE WARMING TREND WILL BE STALLED ON THURSDAY AS A WEAK COLD FRONT
SLIDES THROUGH THE AREA...WITH A MORE ROBUST WARM UP EXPECTED
FRIDAY AND SATURDAY. THE NEXT BIG CHANGE WILL BE SATURDAY NIGHT AS
A STRONGER COLD FRONT SLIDES INTO THE SOUTHERN PLAINS. GENERALLY
SIDED TOWARD THE ECMWF SOLUTION WHICH HAS BEEN CONSISTENT IN
SHOWING THIS FIRST COLD FRONT TO OFFER A MODEST COOL DOWN...AND
QUICKLY FOLLOWED BY A MUCH STRONGER COLD FRONT ON MONDAY. THIS
AIRMASS MARKED BY A 1050+ MB SURFACE PRESSURE WILL PUSH TEMPS WELL
BELOW NORMAL FOR THE FIRST PART OF NEXT WEEK. DRY WEATHER WILL
PREVAIL WITH THE POSSIBLE EXCEPTION OF LIGHT PRECIP ASSOCIATED
WITH THE EARLY WEEK COLD FRONT.
&&
.PRELIMINARY POINT TEMPS/POPS...
TUL 39 20 47 27 / 0 0 0 10
FSM 40 20 46 27 / 10 0 10 10
MLC 40 17 47 27 / 10 0 10 10
BVO 37 13 47 22 / 0 0 0 10
FYV 36 13 42 23 / 10 0 10 10
BYV 36 18 42 27 / 10 0 10 10
MKO 38 16 45 26 / 10 0 10 10
MIO 34 16 45 25 / 0 0 0 10
F10 39 18 46 27 / 0 0 10 10
HHW 39 19 47 28 / 20 10 10 10
&&
.TSA WATCHES/WARNINGS/ADVISORIES...
OK...NONE.
AR...NONE.
&&
$$
LONG TERM....07
AREA FORECAST DISCUSSION
NWS GREENVILLE-SPARTANBURG SC
102 AM EST TUE JAN 15 2013
.SYNOPSIS...
A SURFACE FRONT WILL BECOME STATIONARY OVER THE REGION THROUGH THE
MIDDLE OF THE WEEK AND MAINTAIN HIGH AMOUNTS OF CLOUDINESS AND
CHANCES OF RAIN. HIGH PRESSURE IS EXPECTED TO BUILD IN BRIEFLY FROM
THE NORTH THURSDAY...BEFORE A LOW PRESSURE SYSTEM MOVES NORTHEAST
OUT OF THE GULF OF MEXICO AND TRACKS TOWARD THE SOUTH CAROLINA COAST
THROUGH EARLY FRIDAY.
&&
.NEAR TERM /THROUGH TODAY/...
930 PM UPDATE...CURRENT FORECAST IS ON TRACK. THE FRONTAL BOUNDARY
HAS MOVED THROUGH THE NC MOUNTAINS AND CURRENTLY LOCATED FROM
NORTHEAST GEORGIA...NE THROUGH THE NC FOOTHILLS. SOLID PRECIP BANDS
ALONG AND NORTH OF THE FRONT WERE MOVING EASTWARD ACROSS
NORTHEAST GEORGIA AND NC MOUNTAINS. THESE BANDS OF PRECIP WILL
CONTINUE TO PROGRESS EAST ACROSS THE REST OF OUR CWA OVERNIGHT
HOURS.
AT 215 PM...MAIN FEATURE DURING THE NEAR TERM OF THE FORECAST WILL
BE THE SE TO NE ORIENTED FRONTAL BOUNDARY THAT IS CURRENTLY LOCATED
FROM NORTHERN GA...NE THROUGH THE NC MOUNTAINS. A WAVE OF LOW
PRESSURE WAS ALONG THE NC/SC BORDER BETWEEN AVL AND CEU AT 18Z. AS
THE WAVE MOVES EAST INTO THE NC PIEDMONT LATE THIS AFTERNOON...THE
FRONTAL BOUNDARY WIL BE ALLOWED TO SAG SOUTHWARD INTO THE NORTHERN
PORTION OF THE SC UPSTATE AND THE SOUTHERN NC PIEDMONT. THE BOUNDARY
IS THEN EXPECTED TO REMAIN QUASI-STATIONARY IN THAT POSITION THROUGH
TUE AS DEEP LAYERED SW FLOW REMAINS OVER THE AREA AND ROUGHLY
PARALLEL WITH THE FRONT..
RAINFALL WILL CONTINUE TO BE WIDESPREAD...ESPECIALLY ACROSS THE NC
MOUNTAINS. LOCATIONS IN GRAHAM AND SWAIN COUNTIES HAVE ALREADY
PICKED UP IN EXCESS OF 2 INCHES OF RAIN AND COUNTY OFFICIALS REPORT
THAT STREAMS ARE RUNNING HIGH. REGIONAL RADARS CONTINUE TO SHOW THE
HEAVIEST RAINFALL OCCURING IN THOSE AREAS...AND THAT SHOULD CONTINUE
FOR SEVERAL MORE HOURS. SOME AREAL FLOODING MAY OCCUR AND MAY NEED
TOP BE ADDRESSED EVENTUALLY IN AN AREAL FLOOD WARNING. THE CURRENT
FLOOD WATCH IS WELL PLACED AND WILL CONTINUE IT IN TIME AND SPACE.
MODELS ARE INDICATING THAT THE BEST UPPER DIVERGENCE WILL GRADUALLY
BECOME ESTABLISHED WEST OF THE NC MOUNTAINS OVER EASTERN TN AS AN
UPPER JET STREAK MOVES INTO THE LOWER GREAT LAKES. STAYED CLOSE TO
HPC QPF WITH SOME MODIFICATIONS FOR LOCAL AFFECTS USING GMOS. THIS
QPF FORECAST INDICATES THAT WIDESPREAD SIGNIFICANT FLOODING SHOULD
NOT OCCUR.
THE TEMPERATURE FORECAST WILL BE A CHALLENGE...ESPECIALLY ACROSS THE
PIEDMONT AREAS WHERE A TIGHT GRADIENT WILL EXIST IN THE VICINITY OF
THE FRONTAL BOUNDARY. SOUTHERN AREAS THIS AFTERNOON HAVE TEMPS IN
THE MID 70S...AND SOMETHING SIMILAR IS LIKELY TO OCCUR TUE
AFTERNOON. USED A BLEND OF MOS AND NAM12 TO CREATE MIN/MAX TEMP
GRIDS. WILL CONTINUE TO FORECAST CATEGORICAL POPS OVER THE
MOUNTAINS...TAPERING TO A LOW CHANCE OF SOUTHERN AREAS.
&&
.SHORT TERM /TONIGHT THROUGH THURSDAY NIGHT/...
AS OF 230 PM MONDAY...H8-H7 FRONTOGENESIS WILL BE STRONGEST WEST OF
THE MOUNTAINS AND NORTHWARD ACROSS THE CENTRAL APPALACHIANS TUE
NIGHT. HOWEVER...A PERIOD OF STRONGER UPSLOPE DEVELOPS ALONG THE
SOUTHERN SLOPES FROM 00-06 UTC WED. I/VE GONE WITH A BLEND OF THE
HPC QPF AND THE WETTER GFS QPF DURING THIS TIME WHICH ADDS ABOUT A
HALF INCH OF PCPN TO THE CURRENT FLOOD WATCH AREAS TUE NIGHT. OWING
TO THIS ADDITIONAL RAINFALL...WE/LL CONTINUE THE FLOOD WATCH THROUGH
12 UTC WED. LATER TUE NIGHT THE LLVL FLOW BECOMES MORE WESTERLY AND
THE LLVL CONVERGENCE WEAKENS AS UPPER DIVERGENCE LIFTS WELL NORTH OF
THE REGION. THIS SHOULD CAUSE PCPN TO BECOME LIGHTER AND END SHORTLY
AFTER 12 UTC OVER THE FORECAST AREA. DOWNSLOPE FLOW AND A FAIRLY
MILD AIRMASS SHOULD HELP TEMPS WARM TO AROUND 60 OVER THE PIEDMONT
WEDNESDAY AFTERNOON. IN FACT...IT MAY BE A FEW DEGREES WARMER THAN
THAT.
A SRN STREAM UPPER LOW WILL APPROACH THE REGION ON THURSDAY. THE NAM
IS SIGNIFICANT OUTLIER AS IT TAKES THE LOW MUCH FARTHER NORTH THAN
THE GFS...CANADIAN OR ECMWF. THE LOW IS ALSO SIGNIFICANTLY STRONGER
ON THAT MODEL. THE 0900 UTC SREF SFC PATTERN IS NOWHERE CLOSE TO THE
NAM/S AND MATCHES THE GLOBAL MODELS BETTER. WE WENT CLOSEST TO THE
GFS FOR THIS RUN. THIS IS STILL WETTER THAN THE 12 UTC ECMWF WHICH
HAS VERY LITTLE PCPN OVER THE FA AS THE WAVE DAMPENS OUT MUCH MORE
QUICKLY AS IT MOVES INTO THE CONFLUENT UPPER FLOW UNDER A DIGGING
NRN STREAM LOW WAVE TROUGH. AT ANY RATE...I DO HAVE A SLIGHT CHANCE
OF SNOW IN THE GRIDS OVER THE MTNS WED NIGHT...BUT THIS SHOULD
AMOUNT TO LITTLE OR NOTHING. PCPN CHANCES GRADUALLY INCREASE ON THU.
FOR NOW...ANY WINTRY MIX DURING THE DAYLIGHT HOURS WILL BE CONFINED
TO THE HIGHER MTN ELEVATIONS NEAR THE TN LINE.
&&
.LONG TERM /FRIDAY THROUGH MONDAY/...
AS OF 230 PM EST MONDAY...THE MEDIUM RANGE MODEL GUIDANCE HAS SHOWN
SOME IMPROVED RUN-TO-RUN CONSISTENCY AND CONSENSUS WITH REGARD TO
MOVING A DEAMPLIFYING UPPER LOW EASTWARD ACROSS THE WESTERN
CAROLINAS THURSDAY EVENING. THE 00Z ECMWF AND 12Z GFS WERE IN
GENERAL AGREEMENT WITH THE BEST FORCING MOVING MAINLY ACROSS THE NE
GEORGIA AND UPSTATE SC PART OF THE FCST AREA EARLY THURSDAY
EVENING...SO CONFIDENCE IS INCREASING THAT WE WILL SEE SOME PRECIP
THURSDAY EVENING. HOWEVER...THAT THOUGHT IS TEMPERED BY A LOOK AT
THE 12Z ECMWF WHICH KEEPS THE BETTER PRECIP TO THE SOUTH AND EAST OF
UPSTATE SC THURSDAY EVENING. THAT IS A GOOD INDICATOR OF OUR
CONFIDENCE PROBLEM GOING FORWARD WITH THIS FCST. EVEN THE FARTHER
SOUTH NEW ECMWF WOULD BRING MEASURABLE PRECIP OVER THE SRN HALF...SO
PRECIP CHANCES WERE ALLOWED INTO TO THE LIKELY CATEGORY MOST PLACES
ALONG AND S OF I-85...WITH CHANCES ELSEWHERE. THE PRECIP WILL BE
RELATIVELY SHORT LIVED AS THE FORCING MOVES QUICKLY EAST OF THE FCST
AREA BY AROUND DAYBREAK FRIDAY...ASSUMING THIS TIMING HOLDS...WHICH
IS A BIG ASSUMPTION. PRECIP TYPE IS THE MAIN CONCERN...BASED ON A
CONSIDERATION OF PARTIAL THICKNESS ON BOTH MODELS. THE FCST LARGELY
FOLLOWED THE GFS AND ITS THERMAL PROFILES FOR P-TYPE DETERMINATION.
THAT SAID...THERE IS NOT MUCH OF A WARM NOSE...SO IT LOOKS MAINLY
LIKE A RAIN OR SNOW PROSPECT FOR THURSDAY EVENING. LOW LEVELS AND
MIN TEMPS LOOK LIKE THEY WILL REMAIN TOO WARM OVER UPSTATE SC AND NE
GEORGIA FOR ANYTHING BUT A COLD RAIN. OVER THE MTNS...SNOW LEVELS
SHOULD DROP DOWN TO THE VALLEY FLOORS OVERNIGHT. THE PRECIP AMTS ON
THE GFS WOULD SUPPORT A LIGHT ACCUMULATION OF SNOW OVER MAINLY THE
CENTRAL AND NRN MTNS...BUT THERE REMAINS MUCH UNCERTAINTY AS TO QPF.
MOST OF THE NC PART E OF THE BLUE RIDGE WOULD ALSO SEE MAINLY A COLD
RAIN...BUT WITH SOME POTENTIAL FOR BRIEF CHANGEOVER TO SNOW SHOWERS
AS THE PRECIP WAS ENDING. SO FOR NOW...WE LEAVE IT AS A CHANCE OF
SOME WINTRY PRECIP OVER THE MTNS LATE THURSDAY AND THURSDAY NIGHT...
AND WE WATCH MODEL TREND FOR MORE CONSISTENCY.
THE REST OF THE MEDIUM RANGE LOOKS UNEVENTFUL. WE REMAIN DRY
UNDERNEATH A LONG WAVE UPPER TROF...SO HIGH PRESSURE WILL REMAIN IN
CONTROL. HOWEVER...THE REALLY COOL AIR WILL REMAIN TO OUR N...SO
EXPECT TEMPS TO BE FAIRLY CLOSE TO NORMAL.
&&
.AVIATION /06Z TUESDAY THROUGH SATURDAY/...
AT KCLT...VFR CONDITIONS ARE EXPECTED TO REMAIN IN PLACE FOR A TIME
TONIGHT BEFORE WORSENING. A NEARLY STATIONARY FRONT IN THE AREA
CONTINUES TO BE THE FOCUS FOR RAINFALL EASILY PRODUCING MVFR VSBY AS
WELL AS CIGS AS LOW AS LIFR. THIS FRONT WILL GRADUALLY SAG SOUTHWARD
LATE TONIGHT...WHICH INCREASES THE LIKELIHOOD OF SEEING
RESTRICTIONS. FURTHERMORE...LOW CLOUDS MAY ADVECT IN FROM SC/GA
FOLLOWING THE DEEP SOUTHWEST FLOW ALOFT. HAVE TAKEN THE SITE TO LOW
MVFR FOR THE EARLY MORNING HOURS BUT WILL BE CLOSELY WATCHING FOR
NEARBY IFR. MOST OF THE RAIN APPEARS TO BE NORTH OF THE FRONTAL ZONE
SO HAVE REMOVED PREVAILING RA FROM OVERNIGHT PERIOD. HOWEVER RAIN IS
CERTAINLY NOT OUT OF THE QUESTION AND ADDITIONAL RESTRICTIONS COULD
ACCOMPANY ANY RAIN. GUIDANCE INDICATIVE OF LOWERING CIGS TUE EVENING
TOO SO HAVE BROUGHT CATEGORY DOWN TO IFR AT THAT TIME. WITH THE
FRONTAL BOUNDARY STRADDLING THE AREA AND POSSIBLY WAVERING BACK AND
FORTH...IT IS DIFFICULT TO CONFIDENTLY NAIL THE TIMING OF WIND SHIFT
/OR SHIFTS/. HAVE TENTATIVELY GONE IN THE NAM/S FAVOR AND MAINTAINED
SOUTHERLY WINDS THROUGH THE NIGHT BEFORE GOING CALM NEAR
DAYBREAK...WITH NORTHERLY WINDS SETTLING IN THEREAFTER.
ELSEWHERE...MUCH LIKE KCLT RESTRICTIONS WILL BE WIDESPREAD AROUND
THE SITES WITH THE LINGERING FRONTAL BOUNDARY. FAVORED A LAMP/RAP
BLEND FOR CIG HEIGHTS OVERNIGHT DUE TO THEIR HANDLING OF CURRENT
CONDITIONS...THEN FAVORED A LAMP/MAV BLEND TOMORROW AS THE RUC PINS
THE CIGS TOO CLOSELY TO PRECIP DISTRIBUTION. GENERALLY MVFR CIGS
WILL LOWER TO IFR AT MOST SITES TONIGHT INTO EARLY TUE...WITH MVFR
RETURNING FOR MUCH OF THE DAYTIME HOURS. SOME GUIDANCE EVEN TAKES
SOUTHERN SITES BACK TO VFR PERIODICALLY TUE AFTN. HOWEVER THERE IS A
STRONG SIGNAL FROM GUIDANCE THAT IFR WILL RETURN FOR TUE NIGHT. THE
FRONTAL BOUNDARY WILL GRADUALLY MOVE SOUTHWARD DURING THE PERIOD
WHICH SUGGESTS COOLER AIR WILL MOVE IN...LEADING TO COOLER NEAR SFC
AIR THAT COULD HELP PRODUCE STRATUS AND/OR FOG GIVEN THE MOIST SOILS
AND AIR. WINDS WILL BE NORTH TO NORTHEAST ON THE NORTH SIDE OF THE
FRONT AND SOUTH TO SOUTHWEST ON THE SOUTH SIDE. TIMING/POSITIONING
OF THE BOUNDARY DIFFERS BETWEEN MAJOR MODELS AND I HAVE FAIRLY LOW
CONFIDENCE IN WIND FCST...BUT IN GENERAL THE NORTHERN SITES WILL SEE
WINDS SHIFT EARLIEST AS THE FRONT WILL SLOWLY BE MOVING SOUTH
THROUGH THE TAF PERIOD. KHKY LOOKS TO BE THE ONLY SITE WHICH WILL
REMAIN OUT OF A REASONABLY CONSTANT DIRECTION THROUGH 06Z WED.
OUTLOOK...RAIN AND RESTRICTIONS WILL REMAIN WIDESPREAD THROUGH
TUESDAY NIGHT. GRADUAL DRYING IS EXPECTED STARTING WED AND
CONTINUING INTO THU WITH CONDITIONS BECOMING VFR ON WED. A LOW
PRESSURE SYSTEM MOVING ALONG THE GULF COAST LATE IN THE WEEK WILL
SPREAD PRECIP AND RESTRICTIONS BACK INTO THE AREA THU NIGHT THROUGH
FRI.
AN EXPERIMENTAL AVIATION FORECAST CONSISTENCY TABLE SHOWING THE
PERCENTAGE OF GUIDANCE MEMBERS AGREEING WITH THE SCHEDULED ISSUANCE
CATEGORY IS AVAILABLE AT THE FOLLOWING LINK (USE LOWER CASE)...
WWW.WEATHER.GOV/GSP/AVIATION_TABLES
&&
.GSP WATCHES/WARNINGS/ADVISORIES...
GA...FLOOD WATCH THROUGH WEDNESDAY MORNING FOR GAZ010.
NC...FLOOD WATCH THROUGH WEDNESDAY MORNING FOR NCZ048-051-052-058-
059-062.
SC...NONE.
&&
$$
SYNOPSIS...SBK
NEAR TERM...JOH/LG
SHORT TERM...MCAVOY
LONG TERM...PM
AVIATION...WIMBERLEY
AREA FORECAST DISCUSSION
NWS FORT WORTH TX
1146 PM CST MON JAN 14 2013
.AVIATION...
MODELS CONTINUE TO SHOW ONLY VERY LOW CHANCES OF WINTER PRECIP IN
METROPLEX WITH NO ACCUMULATIONS. HAVE NOT ADDED WINTRY PRECIP TO
TAFS.
HAVE ADDED TEMPO -PL TO WACO TAF NEAR SUNRISE AS GFS/NAM MODELS
NOW SHOW A SATURATED AREA BELOW 700MB COMBINED WITH LIFT THROUGH
THE LAYER. 04Z RAP KEEPS MOISTURE MUCH MORE SHALLOW...AS DID THE
18Z TTU WRF. GFS/NAM 290K ISENTROPIC SURFACE SHOWS THE LIFT
BEST. 84
&&
.UPDATE...
A VERY DEEP TROUGH CONTINUES TO ROTATE THROUGH NEW MEXICO THIS
EVENING. INCREASING LARGE SCALE LIFT ALONG WITH SOME WEAK UPSLOPE
FLOW CONTINUES TO PRODUCE AREAS OF LIGHT SNOW ACROSS EASTERN NEW
MEXICO AND THE WESTERN TEXAS PANHANDLE. THE LATEST COMPUTER
GUIDANCE INCLUDING HIGH RES SOLUTIONS ALL HOLD PRECIP OFF ACROSS
NORTH TEXAS UNTIL WELL AFTER 06Z. ALL SOLUTIONS KEEP PRECIP
AMOUNTS LIGHT. AT THIS TIME WE SEE NO REASON TO DISAGREE SINCE
MOISTURE WILL BE LIMITED OVER MOST OF THE AREA. STILL FEEL THAT
LIGHT FREEZING RAIN AND SLEET WILL BE POSSIBLE...ESPECIALLY ACROSS
THE SOUTH/SOUTHEAST ZONES. WILL HOLD OFF ON ANY TYPE OF ADVISORY
AT THIS TIME.
WILL ONLY MAKE SOME MINOR CLOUD COVER AND TEMPERATURE CHANGES WITH
THIS UPDATE.
79
&&
.PREV DISCUSSION... /ISSUED 303 PM CST MON JAN 14 2013/
THE FORECAST OVER THE NEXT SEVERAL DAYS REMAINS DIFFICULT AS
THERE IS THE POSSIBILITY OF THE OCCURRENCE OF WINTER WEATHER THREE
TIMES THROUGH THURSDAY MORNING. LATEST WATER VAPOR IMAGERY SHOWS A
DEEP TROUGH OVER THE WESTERN CONUS...WITH SOUTHWESTERLY FLOW
SETUP ACROSS TEXAS AND INTO THE OHIO VALLEY AHEAD OF THE TROUGH. A
DISTURBANCE CAN CURRENTLY BE SEEN IN EASTERN MISSOURI AND IT WAS
THIS DISTURBANCE WHICH BROUGHT SLEET AND FREEZING RAIN TO PORTIONS
OF NORTH TEXAS THIS MORNING.
ANOTHER ROUND OF WINTER WEATHER IS AGAIN POSSIBLE TONIGHT. AN IMPULSE
OF ENERGY CAN BE SEEN ROUNDING THE BASE OF THE TROUGH AND EXPECT
THIS FEATURE TO MOVE THROUGH THE FORECAST AREA AROUND DAYBREAK.
MODELS ARE IN VERY GOOD AGREEMENT OF DEEP LIFT ON ISENTROPIC
SURFACES...IN THE MID-LEVELS OF THE ATMOSPHERE. THE GFS/ECMWF
INDICATE SHARP MOISTURE ADVECTION THAT IS EVIDENT ON 700 MB
THETA-E PLOTS BY 12Z. THIS WARM AIR/MOISTURE ADVECTION WILL PROVIDE
SUFFICIENT LIFT FOR PRECIPITATION...AS LONG AS MOISTURE THROUGHOUT
THE ATMOSPHERIC COLUMN IS ADEQUATE. THE GFS/ECMWF/CANADIAN ALL
HAVE PROFILES THAT SUPPORT LIGHT PRECIPITATION WHILE THE NAM...IS
DRIER IN THE LOWER ATMOSPHERE AND WOULD ONLY SUPPORT TRACE AMOUNTS
OF PRECIP. THE NEXT VARIABLE TO DETERMINE WINTER PRECIP CHANCES
WILL BE THE SURFACE TEMPERATURES. IT DOES APPEAR THAT THE TEMPS BY
MORNING SHOULD BE AT OR BELOW FREEZING FOR THE ENTIRE CWA...AND A
SLEET/FREEZING RAIN MIXTURE WOULD BE THE PREDOMINANT PRECIP TYPE.
IF TEMPS ARE A BIT WARMER ACROSS THE EXTREME SOUTHERN COUNTIES
THEN RAIN/SLEET WOULD OCCUR. HIGHEST CHANCES FOR PRECIP/ACCUMULATIONS
WILL ONCE AGAIN BE ACROSS THE SOUTHERN ZONES...WHERE THE BEST
MOISTURE IS LOCATED. CONFIDENCE IS INCREASING THAT FROZEN PRECIP
WILL IMPACT SOME LOCATIONS ACROSS THE SOUTHEASTERN ZONES...BUT
CONFIDENCE OF WIDESPREAD IMPACTS ARE NOT HIGH AND WILL NOT ISSUE A
WINTER WEATHER ADVISORY AT THIS TIME. WILL HANDLE THE EXPECTED
IMPACTS WITH A SPECIAL WEATHER STATEMENT AND IF COVERAGE OF WINTER
PRECIP APPEARS TO BE HIGHER...FUTURE SHIFTS MAY UPGRADE TO AN
ADVISORY. MODELS...SHOW LITTLE MOISTURE FURTHER NORTH INTO THE
METROPLEX...BUT LIFT COULD BE ENOUGH TO TAP INTO WHAT LITTLE
MOISTURE IS AVAILABLE AND PRODUCE SNOW GRAINS OR SLEET SIMILAR TO
LAST NIGHT. WILL MENTION SLEET WITH A 10 POP...BUT NO
ACCUMULATIONS ARE EXPECTED.
THE FOCUS AFTER TOMORROW MORNING WILL SHIFT TO WEDNESDAY/THURSDAY
WHEN THE UPPER TROUGH CLOSES OFF AND MOVES ACROSS NORTH TEXAS.
THERE REMAINS CONSISTENCY BETWEEN THE GFS/ECMWF/CANADIAN ON A
POSITIVELY TILTED TROUGH CLOSING OFF JUST WEST OF THE CWA AND
REMAINING IN ITS POSITIVE TILT AS IT MOVES ACROSS NORTH TEXAS.
THIS SOLUTION WOULD KEEP THE 850/700 MB FLOW FROM THE
WEST/SOUTHWEST WHICH ALLOWS FOR NO MOISTURE TO ADVECT INTO THE
AREA...AND THUS THESE SOLUTIONS FORECAST DRY WEATHER. THIS
POSITIVE TILT ALSO PROVIDES FORCING FOR THE 850/700 FRONTS TO PUSH
SOUTH OF THE FORECAST AREA BY WEDNESDAY MORNING...AND THEREFORE WE
WOULDNT HAVE A THIRD MORNING OF WINTER WEATHER ACROSS THE
SOUTHEASTERN ZONES. ONCE THE TROUGH PASSES NORTH TEXAS...IT IS
FORECASTED TO BECOME NEUTRAL AND PRECIP IS EXPECTED FOR
LA/MS/AL...BUT THE TROUGH WOULD BE WELL EAST BEFORE MOISTURE IS
ABLE TO BUILD ON THE BACKSIDE OF THE SYSTEM.
THE NAM REMAINS THE OUTLIER AND CUTS OFF THE SYSTEM A BIT SOONER
THAN THE REST OF THE GUIDANCE AND GIVES IT A NEUTRAL ORIENTATION
BEFORE IT ARRIVES INTO NORTH TEXAS. THIS WOULD ALLOW FOR MOIST
ADVECTION/WARM AIR ADVECTION AHEAD OF THE SYSTEM AND RAIN WOULD
OCCUR IN ADVANCE OF THE TROUGH WEDNESDAY AFTERNOON...WITH THE
POSSIBILITY OF ANOTHER ROUND OF WINTER WEATHER ACROSS THE EXTREME
SOUTH WEDNESDAY MORNING. MOISTURE THEN WOULD BE ABLE TO BE
TRANSPORTED ON THE BACKSIDE OF THE SYSTEM AND THEN ANOTHER ROUND
OF WINTER PRECIP IN THE FORM OF SNOW WOULD BE POSSIBLE WEDNESDAY
NIGHT. THIS SOLUTION IS NOT SUPPORTED BY OTHER GUIDANCE AND WILL
KEEP THE FORECAST MOSTLY DRY WEDNESDAY AND THURSDAY. WILL ONLY
CARRY A 20 POP WEDNESDAY AFTERNOON AND EVENING AHEAD OF THE FRONT
WHEN THE BEST LIFT OVERSPREADS THE AREA. THIS PRECIP WOULD BE IN
THE FORM OF RAIN. WE STILL HAVE 48 HOURS TO WATCH THIS SYSTEM AND
ADDITIONAL CHANGES ARE POSSIBLE.
COLD TEMPERATURES ARE EXPECTED TO LAST FOR MOST OF THE PERIOD AS
NORTH FLOW REMAINS IN PLACE. SOUTHERLY WINDS RETURN FRIDAY AND
SATURDAY AND HIGHS WILL WARM INTO THE 50S...BUT ANOTHER FRONT
COMES MONDAY AND HIGHS COULD BE BACK INTO THE 40S.
HAMPSHIRE
&&
.PRELIMINARY POINT TEMPS/POPS...
DALLAS-FT. WORTH, TX 27 42 28 50 34 / 5 10 10 10 10
WACO, TX 29 44 26 49 31 / 10 20 10 20 20
PARIS, TX 25 40 24 48 31 / 5 10 10 20 20
DENTON, TX 23 41 23 49 30 / 5 10 10 10 10
MCKINNEY, TX 23 41 24 49 31 / 5 10 10 10 10
DALLAS, TX 29 42 29 50 36 / 5 10 10 10 10
TERRELL, TX 26 41 24 51 31 / 5 10 10 20 20
CORSICANA, TX 29 40 28 49 33 / 10 20 10 20 20
TEMPLE, TX 28 41 27 48 31 / 10 20 10 20 20
MINERAL WELLS, TX 22 43 23 51 30 / 0 10 10 10 10
&&
.FWD WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
/
AREA FORECAST DISCUSSION
NWS MILWAUKEE/SULLIVAN WI
1045 PM CST MON JAN 14 2013
.UPDATE...
.AVIATION/06Z TAFS/...A HIGH PRESSURE RIDGE FROM MO TO SRN WI
WILL SLOWLY SHIFT SEWD ON TUE WITH SWLY WINDS DEVELOPING. THE
AIRMASS WILL REMAIN DRY WITH VFR CONDITIONS FOR TUE AND TUE NT.
&&
.PREV DISCUSSION... /ISSUED 331 PM CST MON JAN 14 2013/
TONIGHT AND TUESDAY...FORECAST CONFIDENCE...HIGH
AN AREA OF LOW LEVEL CLOUDS WILL LIKELY AFFECT THE NORTHWEST HALF OF
THE FORECAST AREA LATE THIS AFTERNOON AND INTO TONIGHT. HIGH LEVEL
CLOUDS ARE POSSIBLE ELSEWHERE. THE LOW LEVEL CLOUDS SHOULD MOVE ON
OR SCATTER OUT BY LATE IN THE NIGHT...WITH SOME MID LEVEL CLOUDS
LINGERING TUESDAY MORNING. SKIES SHOULD BECOME MOSTLY SUNNY BY THE
AFTERNOON.
LOWS A LITTLE TRICKY TONIGHT...ALL DEPENDING ON HOW LONG CLOUDS
STICK AROUND...AS WINDS WILL BE LIGHT. GENERALLY WENT WITH A
CONSENSUS FOR LOWS...AS THE ECMWF/GFS/NAM SOLUTIONS NOT TOO FAR
APART. COULD SEE TEMPS GET A FEW DEGREES COLDER THAN EXPECTED IF
SKIES CLEAR UP SOONER THAN EXPECTED...RESULTING IN A LONGER PERIOD
OF GOOD RADIATIONAL COOLING CONDITIONS. HIGH TEMPS SHOULD BE BACK
AROUND NORMAL TUESDAY...MAYBE EVEN A DEGREE OR TWO ABOVE AVERAGE
VALUES FOR MID JANUARY.
SHORT TERM...TUESDAY NIGHT THROUGH THURSDAY.
MID TO UPPER LEVEL TROUGH AXES SHIFT EAST...WITH SHORT WAVE DROPPING
SE TUESDAY NIGHT/WEDNESDAY IN LEFT EXIT REGION OF UPPER LEVEL JET
MAX TOPPING WESTERN RIDGE AND NOSING INTO THE UPPER MIDWEST. AFTER
THIS WAVE CLEARS THE REGION...MODELS VARY IN PLACEMENT OF CHANNELED
VORTICITY IN CONFLUENT FLOW UNDER HUDSON BAY POLAR VORTEX FOR THE
REST OF THE SHORT TERM BUT GENERALLY KEEP IT TIED TO THE UPPER
JET...STAYING NORTH OF FORECAST AREA.
TUESDAY NIGHT AND WEDNESDAY...FORECAST CONFIDENCE MEDIUM.
TEMPERATURES FALL TUESDAY EVENING WITH READINGS HOLDING STEADY OR
RISING AFTER LOWS ARE REACHED AROUND MIDNIGHT AS SOUTHWEST WINDS
INCREASE AHEAD OF APPROACHING SHORT WAVE. LOCATION OF BEST FORCING
WITH WAVE VARIES WITH MODEL TRACK AND STRENGTH DIFFERENCES.
CONSENSUS KEEPS THE BETTER CHANCES FOR ACCUMULATING SNOW ACROSS NRN
WI...WHICH LEADS TO CHANCE OF LIGHT SNOW IN THE FAR NORTH AND SLIGHT
CHANCE ELSEWHERE MAINLY WEDNESDAY MORNING. BRIEF PERIOD OF LIFT AND
DEEP MOISTURE INTO THE DENDRITE GROWTH ZONE...ALONG WITH
PRECIPITABLE WATER ONLY REACHING 1/3 INCH SO DURING MOST FAVORABLE
TIME FOR PRECIPITATION...MEANS MINIMAL ACCUMULATIONS OF A FEW TENTHS
OF AN INCH AT MOST.
GUSTY WINDS ON WEDNESDAY WITH TIGHT GRADIENT AROUND SOUTHERN CANADA
LOW. AGAIN A CONSENSUS BLEND TEMPERING THE STRONGER NAM WINDS BUT
THIS STILL BRINGS 15 TO 25 MPH SOUTHWEST WINDS...SHIFTING WEST
BEHIND THE SURFACE TROUGH/COLD FRONT...WITH A FEW GUSTS TO 30 MPH.
THE GUSTY SOUTHWEST WINDS PUSH A THERMAL RIDGE AHEAD OF SURFACE
TROUGH OVER THE CWA MIDDAY...WITH BLENDED TEMPERATURES BRINGING
HIGHS IN THE LOWER TO MIDDLE 30S...THOUGH TEMPS COULD BE LOWER IF
FASTER MOVEMENT OF COLD FRONT REFLECTED IN THE GFS AND GEMNH OCCURS.
WEDNESDAY NIGHT AND THURSDAY...FORECAST CONFIDENCE MEDIUM TO HIGH.
WEST-NORTHWEST FLOW BEHIND LOW SHUNTS COLDEST AIR OFF TO THE
NORTHEAST OF THE REGION OVER SOUTHEAST CANADA...BUT ENOUGH COLD AIR
ADVECTION TO BRING SINGLE DIGIT LOWS TO THE NORTH WEDNESDAY
NIGHT...WITH MID-TEENS IN THE SOUTH. HIGH PRESSURE BRINGS QUIET
WEATHER WITH NEUTRAL TEMPERATURE ADVECTION BRINGING HIGHS IN THE
TEENS NORTH TO LOWER 20S SOUTH.
LONG TERM...THURSDAY NIGHT THROUGH MONDAY. FORECAST CONFIDENCE
LOW TO MEDIUM.
WEAK WAVES PASSING BY TO THE NORTH IN THE NEAR ZONAL FLOW LIFT
850/925MB TEMPERATURES ENOUGH TO WARM HIGHS INTO THE LOWER TO MIDDLE
30S FOR FRIDAY AND SATURDAY. FAR NORTH MAY BE BRUSHED BY LIGHT SNOW
WITH THE WARM ADVECTION PUSH THURSDAY NIGHT...AND ONLY A LITTLE
BETTER CHANCE SATURDAY/SATURDAY NIGHT WITH STRONGER WAVE CROSSING
NORTHERN WISCONSIN. COLD ADVECTION AROUND ARCTIC HIGH SETTLING INTO
THE PLAINS BEHIND THIS LAST WAVE BRINGS HIGHS IN THE TEENS
SUNDAY...WITH SINGLE DIGIT LOWS SUNDAY NIGHT. BLENDED HIGHS ON LY IN
THE SINGLE DIGITS TO LOWER TEENS MONDAY...THEN FALLING TO BELOW
ZERO AWAY FROM LAKE MICHIGAN MONDAY NIGHT. IF COLDER GFS PANS
OUT...READINGS COULD GET EVEN COLDER.
AVIATION/00Z TAFS/...
STILL WATCHING AN AREA OF MVFR CIGS UPSTREAM. LATEST RAP AND NAM RH
FIELDS INDICATE THIS MAY HOLD TOGETHER AND MOVE INTO THE NORTHWEST
HALF OF THE FORECAST AREA MID TO LATE THIS AFTERNOON. BEST CHANCE
FOR THESE LOWER CIGS APPEARS TO BE ROUGHLY ALONG AND NORTHWEST OF A
MINERAL POINT TO SHEBOYGAN LINE...AS THE HIGH RH IN THE MODELS NEVER
QUITE MAKES IT TO THE SOUTHEAST. WILL CONTINUE TO KEEP AN EYE ON
SATELLITE TRENDS AND MODIFY TAFS AS NEEDED.
ANY LOWER CIGS SHOULD SCATTER OUT OR MOVE OUT BY MORNING...WITH VFR
CONDITIONS THEN EXPECTED THROUGH THE DAY TUESDAY.
MARINE...
SOUTHWEST WINDS WILL INCREASE TUESDAY NIGHT AHEAD OF AN APPROACHING
TROUGH OF LOW PRESSURE. WIND GUSTS ARE EXPECTED TO PEAK IN THE 30-35
KT RANGE LATE TUESDAY NIGHT THROUGH WEDNESDAY MORNING. MODELS
CURRENTLY INDICATING GUSTS RIGHT ON THE VERGE OF GALE
FORCE...ESPECIALLY TOWARD OPEN WATERS...SO WILL GO WITH A GALE WATCH
FOR THIS PERIOD OF HIGHER GUSTS. WILL LIKELY SEE GUSTS TO SMALL
CRAFT LEVELS EARLIER IN THE NIGHT AS THINGS RAMP UP...AND INTO
WEDNESDAY AFTERNOON AS WINDS EASE.
THE HIGHEST WAVES WILL BE ACROSS THE NORTH AND TOWARD OPEN WATERS
DUE TO THE EXPECTED SOUTHWEST FLOW. NOT EXPECTING WAVES WILL GET
PARTICULARLY HIGH GIVEN THE OFFSHORE COMPONENT TO THE WINDS.
&&
.MKX WATCHES/WARNINGS/ADVISORIES...
WI...NONE.
LM...GALE WATCH FROM LATE TUESDAY NIGHT THROUGH WEDNESDAY MORNING FOR
LMZ643>646.
&&
$$
UPDATE...GEHRING
TONIGHT/TUESDAY AND AVIATION/MARINE...DDV
TUESDAY NIGHT THROUGH MONDAY...REM
AREA FORECAST DISCUSSION
NWS GAYLORD MI
1024 AM EST TUE JAN 15 2013
.SYNOPSIS...
ISSUED AT 346 AM EST TUE JAN 15 2013
SEVERAL AREAS OF LOW PRESSURE AND COLD FRONTS WILL CROSS NORTHERN
MICHIGAN OVER THE NEXT SEVERAL DAYS. THIS WILL PRODUCE PERIODS OF
LAKE EFFECT AND LAKE ENHANCED SNOW SHOWERS...WHICH WILL PRIMARILY
AFFECT EASTERN UPPER AND NORTHWEST LOWER MICHIGAN.
&&
.UPDATE...
ISSUED AT 935 AM EST TUE JAN 15 2013
STRATO-CU HAS LARGELY ERODED THIS MORNING AS DEEP DRY AIR ABOVE
850MB MIXES OUT LOW LEVEL MOISTURE. STILL SEEING AN AREA OF LOW
LEVEL MOISTURE HUGGING THE LAKE MICHIGAN SHORELINE FROM FRANKFORT
SOUTHWARD. WILL LARGELY DISREGARD THE "MOIST" NAM TODAY...WHICH
IS MUCH TOO PESSIMISTIC WITH WIDESPREAD CLOUDINESS ACROSS
NORTHERN MICHIGAN THIS AFTERNOON. COMBO OF LINGERING LOW LEVEL
MOISTURE ALONG THE COASTLINE AND A FEW UPSTREAM PATCHES OF MID
CLOUD OVER WISCONSIN MAY INTERACT WITH STILL PLENTIFUL OVERLAKE
INSTABILITY TO PRODUCE A FEW AFTN FLURRIES CLOSER TO THE LAKE
MICHIGAN COAST. INLAND AREAS SHOULD SEE A GOOD AMOUNT OF SUNSHINE.
CURRENT TEMP FORECAST LOOKS GOOD AND WILL MAKE ONLY SOME MINOR
CHANGES BASED ON CURRENT OBSERVATIONS.
UPDATE ISSUED AT 639 AM EST TUE JAN 15 2013
BIG UPDATES EARLY THIS MORNING...AS THE STRATO CU OFF THE LAKES
HAS RAPIDLY ERODED...LEAVING CLEARING SKIES MOST AREAS...WITH ONLY
SOME SCATTERED FLURRIES. WITH NO DISCERNIBLE MID LEVEL CLOUD
UPSTREAM...OUTSIDE OF A SMALL AREAS IN NORTH CENTRAL
WISCONSIN...WILL DISREGARD NAM/GFS TRAPPED IN SHALLOW STRATO CU
MOSTLY CLOUDY SKY FOR THE DAY. RATHER...WILL OPT TO KEEP SKIES ON
THE CLEARER SIDE FOR THE DAY. THIS AGREED UPON BY LATEST RUC DATA.
AS WINDS INCREASE TONIGHT...MAYBE SOME ADDITIONAL MOISTURE FLUX
OFF THE LAKES...BUT EVEN HERE...DATA SUGGESTS THAT THE ATMOSPHERE
DRIES OUT LATE...PRIOR TO NEXT UPSTREAM CLIPPER/COLD FRONT SET FOR
WEDNESDAY.
&&
.SHORT TERM...(TODAY THROUGH TONIGHT)
ISSUED AT 346 AM EST TUE JAN 15 2013
EARLY MORNING REGIONAL ANALYSIS SHOWS HIGH PRESSURE STRETCHED OUT
ACROSS THE WESTERN LAKES ON FRONT SIDE OF POSITIVELY TILTED DEEP MID
LEVEL TROUGH AXIS EXTENDING FROM HUDSON BAY DOWN TO NEAR THE FOUR
CORNERS. LIGHT WSW FLOW CONTINUES TO ROTATE AROUND NORTH EDGE OF
SURFACE RIDGE AXIS ACROSS THE NORTHERN LAKES. THIS...COMBINED WITH
MORE THAN SUFFICIENT DELTA T/S (RAP ANALYSIS SHOWS H85 TEMPS IN THE
NEGATIVE MID TEENS) AND SLIGHT UPTICK IN LOW LEVEL MOISTURE...HAS
KICKED OFF GENERALLY LIGHT LAKE INDUCED SNOWS ACROSS NORTHWEST LOWER
MICHIGAN. NICE FLUFF FACTOR...HOWEVER...WITH LAKE INDUCED MOISTURE
AXIS REMAINING PEGGED IN THE DGZ...AS NOTED BY LARGE DENDRITIC
CONGLOMERATES FALLING HERE AT THE OFFICE. NO REPORTS YET...BUT NO
DOUBT AT LEAST SOME LIGHT ACCUMULATIONS OCCURRING UNDER WEAK BANDING
STRUCTURES. FORECAST CONCERNS THROUGH THE SHORT TERM CONTINUE TO
CENTER ON MESOSCALE LAKE SNOW TRENDS.
MARGINAL LAKE PROCESSES TO CONTINUE THROUGH TODAY AS SUFFICIENT
LAKE/AIR TEMPERATURE DIFFERENCE REMAINS PARTIALLY OFFSET BY LOW
INVERSION HEIGHTS AND LIMITED MOISTURE. MODEL DERIVED SOUNDINGS
CONCUR...WITH NOTED INVERTED-V DEVELOPMENT IN SURFACE BASED
ENVIRONMENT AS UPSTREAM DRY SURGE REPLACES CURRENT UPTICK IN LOW
LEVEL MOISTURE. "BEST" ACTIVITY EXPECTED EARLY ON THIS MORNING IN
FAVORED W TO WSW FLOW REGIMES OF NORTHWEST LOWER...WITH PERHAPS AN
ADDITIONAL INCH OR TWO UNDER THE MORE PERSISTENT BANDS. MUCH LIKE
YESTERDAY...EXPECT A DOWNWARD TREND IN BOTH INTENSITY AND COVERAGE
THROUGH THE DAY AS FLOW ONCE AGAIN BACKS AROUND TO SOUTHWEST BY THIS
AFTERNOON. POSSIBLY THINGS MAY END ALL TOGETHER (ALSO LIKE
YESTERDAY)...BUT DON`T WANT TO GO THIS OPTIMISTIC JUST YET. EITHER
WAY...NOT A BIG DEAL THIS AFTERNOON WITH ANY SNOW AMOUNTS LIKELY
REMAINING VERY LIGHT. NOT TOO SHABBY OF A DAY AWAY FROM THE FAVORED
LAKE PRONE AREAS OF NORTHWEST LOWER/SOUTHERN PORTIONS OF EASTERN
UPPER...WITH PARTLY TO MOSTLY CLOUDY SKIES AND TEMPERATURES IN THE
20S.
STORY REMAINS UNCHANGED THROUGH THIS EVENING WITH MARGINAL
INSTABILITY KICKING OFF SCATTERED LIGHT SNOW SHOWERS IN SOUTHWEST
FLOW AREAS. ALBERTA CLIPPER/COLD FRONT APPROACH THE WESTERN LAKES
LATE...WITH TRENDS SUPPORTING ATTENDANT MOISTURE AXIS NOT REACHING
OUR AREA UNTIL AFTER SUNRISE. WEAK PRE-FRONTAL WAA AND CONTINUOUS
FEED OF LOW LEVEL DRY AIR SHOULD CONTINUE TO SUBSTANTIALLY HINDER
LAKE PROCESSES THROUGH THE OVERNIGHT...DESPITE STEADY UPTICK IN
OVER-WATER WIND SPEEDS. EXPECT ANY SNOWFALL AMOUNTS TO REMAIN UNDER
AN INCH. UPTICK IN WINDS UNDER INCREASING PRESSURE GRADIENT REGIME
WILL OFFSET PARTLY TO MOSTLY CLEAR SKIES ELSEWHERE...NOT ALLOWING
TEMPERATURES TO DROP TOO MUCH. INHERITED LOW IN THE TEENS AND 20S
LOOK GREAT.
.LONG TERM...(WEDNESDAY THROUGH MONDAY)
ISSUED AT 346 AM EST TUE JAN 15 2013
WEDNESDAY AND WEDNESDAY NIGHT...UPPER LEVEL TROUGHING WILL BE
SITUATED OVER THE NRN GREAT LAKES...SHARPENED BY SHORTWAVE ENERGY
DIVING INTO THE REGION. THE ASSOCIATED CLIPPER/LOW PRESSURE WILL
PASS THROUGH ONTARIO...WITH A FAIRLY STRONG COLD FRONT TO CROSS
NRN MICHIGAN WEDNESDAY NIGHT. SW WINDS AHEAD OF THE FRONT WILL
GRADUALLY SHIFT AROUND TO OUT OF THE NW BY THURSDAY MORNING.
ENHANCED MOISTURE WITH THE FRONT WILL BRING SOME LIGHT SYNOPTIC
SNOWS WEDNESDAY...ENHANCED TO A MARGINAL DEGREE BY H8 TEMPS OF
-8C. NOT IMPRESSED WITH THE SNOWFALL INTENSITIES...AS INVERSION
HEIGHTS ONLY BRIEFLY RISE TO 5KFT...WITH WSW FLOW POINTING BEST
SNOWS ALONG FAR NW LOWER AND INTO EASTERN UPPER. LOWERED SNOWFALL
AMOUNTS BASED ON TURNING WINDS...AND ONLY A BRIEF PERIOD OF MORE
MODERATE ACTIVITY WITH THE FRONT. SECONDARY SHORTWAVE ENERGY AND
DEEPER MOISTURE WILL ENHANCE SNOW SHOWERS AT NIGHT...WHILE H8
TEMPS PLUMMET TO -22C NORTH/-16C SOUTH. AGAIN...WINDS ARE SHIFTING
OVER TIME...WITH INVERSION HEIGHTS 5KFT NORTH TO 4000 FEET SOUTH.
WHILE IT WILL OBVIOUSLY BE SNOWING FOR CATEGORICAL POPS...ACCUMS
NOT EXPECTED TO BE THRILLING AT 1-3" IN THE FAVORED AREAS FOR BOTH
OF THESE PERIODS (CHIP COUNTY IN EASTERN UPPER AND IN THE HIGHER
TERRAIN OF INTERIOR NRN LOWER AROUND GAYLORD. HIGHS AROUND 30F
WEDNESDAY WILL FALL INTO THE SINGLE DIGITS AND TEENS WEDNESDAY
NIGHT.
THURSDAY THROUGH FRIDAY...MOISTURE/COLD AIR REMAIN SUFFICIENT
THROUGH THURSDAY NIGHT FOR CONTINUED LIGHT LAKE EFFECT
ACCUMULATIONS. WNW WINDS WILL BE BACKING WITH TIME WITH LESS
MOISTURE. INVADING HIGHER PRESSURE WILL ALSO TURN THE WINDS MORE
ANTICYCLONIC THROUGH THEN WITH MAYBE A COUPLE OF INCHES IN SPOTS
IN NRN CHIP COUNTY AND FAR NW LOWER. THEN...THE NEXT CLIPPER
ARRIVES FRIDAY WITH STRONGER SW FLOW AND WARMING EXPECTED THROUGH
THE DAY FRIDAY. A WING OF WARM FRONTAL SYNOPTIC SNOWS...AND
BRIEF SW FLOW ENHANCEMENT FOR FRIDAY MORNING BEFORE THE
TEMPERATURES RISE/INVERSION HEIGHTS FALL.
FRIDAY NIGHT THROUGH EARLY NEXT WORK WEEK...LOW PRESSURE AND YET
ANOTHER COLD FRONT...SLOW MOVING...SLIDE IN ACROSS NRN MICHIGAN.
BEST LOW LEVEL CONVERGENCE AND RESULTING SNOWFALL WILL BE IN
EASTERN UPPER FRIDAY NIGHT INTO EARLY SATURDAY...BEFORE SHIFTING
SOUTH INTO NRN LOWER LATE SATURDAY AND SATURDAY NIGHT. WIND
DIRECTIONS ARE TOO UNCERTAIN AT THIS POINT...BUT DATA RIGHT NOW
SUGGESTS POOR NE FETCH ACROSS EASTERN UPPER...WITH BETTER NW FLOW
ACROSS NW LOWER FOR THE BEST ACCUMULATIONS. THE ASSOCIATED WAVE
ALOFT IS MORE DEFINED WITH EXPECTED MODEST DEEP LAYER -DIVQ. BY
SUNDAY...WINDS BACK AROUND OUT OF THE NW FOR EASTERN UPPER TO GET
BACK INTO THE LAKE EFFECT...ALONG WITH NW LOWER. SNOWS SUNDAY
NIGHT POSSIBLY ENHANCED YET AGAIN WITH NEXT IN THE SERIES OF
CLIPPERS/WAVES/SYNOPTIC SNOWFALL. LAKE EFFECT CONTINUES BEHIND
THIS CLIPPER INTO MONDAY AND TUESDAY.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z WEDNESDAY MORNING)
ISSUED AT 639 AM EST TUE JAN 15 2013
LOW LEVEL MVFR CIGS HAVE RAPIDLY ERODED...AS DRIER AIR HAS
OVERPOWERED THE LAKE EFFECT. COULD BE A BRIEF PERIOD OR TWO THAT
THESE CLOUDS WILL BE ABLE TO DEVELOP TODAY...BUT SOME UNCERTAINTY
DOES EXIST. LATEST SATELLITE AND RAPID UPDATE DATA SUGGEST THE
CLEARER SCENARIO IS THE ONE TO FOLLOW. MAYBE THIS CLOUD CAN
BRIEFLY FIRE UP THIS EVENING AS SW/WSW WINDS INCREASE IN ADVANCE
OF A CLIPPER SYSTEM/COLD FRONT SET FOR WEDNESDAY...BUT AGAIN...AIR
MASS DRIES LATE IN THE PERIOD. PREVAILING CONDITIONS EXPECTED TO
BE VFR. AS WINDS INCREASE LATE TONIGHT...WIND SHEAR ISSUES
INCREASE...BUT BELIEVE AT THIS POINT...THERE WILL BE ENOUGH OF A
SFC WIND TO PREVENT THE INTRODUCTION OF LLWS INTO THE FORECAST.
&&
.MARINE...
ISSUED AT 346 AM EST TUE JAN 15 2013
COMBINATION OF REMNANT OVER-WATER INSTABILITY AND TIGHTENING
PRESSURE GRADIENT AHEAD OF APPROACHING CLIPPER SYSTEM WILL RESULT
IN A QUICK INCREASE OF SOUTHWEST WINDS ACROSS NORTHERN LAKE
MICHIGAN AND THE STRAITS LATER THIS AFTERNOON...CONTINUING THROUGH
WEDNESDAY. GALES SEEM A CERTAINTY ACROSS CURRENT WATCH AREA
TONIGHT THROUGH WEDNESDAY...SO WILL UPGRADE AT THIS ISSUANCE. GALE
CONDITIONS SEEM INCREASINGLY POSSIBLE ALONG THE THE NORTHERN
PORTION OF LAKE HURON ON WEDNESDAY. STILL SOME LINGERING
UNCERTAINTY... ESPECIALLY ON TIMING. WILL ISSUE A GALE WATCH
WEDNESDAY INTO WEDNESDAY EVENING TO COVER THIS POTENTIAL.
THEREAFTER...A SEASONABLY ACTIVE PERIOD OF WEATHER IS EXPECTED
RIGHT ON INTO NEXT WEEKEND...WITH SEVERAL CLIPPER SYSTEMS CROSSING
THE WATERS... FOLLOWED BY PERIODS OF LAKE EFFECT SNOW. MORE ROUNDS
OF SMALL CRAFT ADVISORY WINDS ARE LIKELY THROUGHOUT THE LATE WEEK
AND WEEKEND.
&&
.APX WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
LH...GALE WARNING FROM 7 PM THIS EVENING TO 4 PM EST WEDNESDAY FOR
LHZ345.
GALE WATCH FROM WEDNESDAY MORNING THROUGH WEDNESDAY EVENING FOR
LHZ346-347.
LM...GALE WARNING FROM 7 PM THIS EVENING TO 4 PM EST WEDNESDAY FOR
LMZ323-341-342-344>346.
LS...NONE.
&&
$$
UPDATE...JK
SYNOPSIS...SD
SHORT TERM...MB
LONG TERM...SD
AVIATION...SD
MARINE...MB
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
703 AM EST TUE JAN 15 2013
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 500 AM EST TUE JAN 15 2013
WV IMAGERY AND RUC ANALYSIS INDICATED A RIDGE OFF THE WEST COAST AND
A BROAD MID/UPPER LEVEL TROUGH FROM NW OF HUDSON BAY THROUGH NRN
MANITOBA/NW ONTARIO AND THE CNTRL PLAINS INTO NEW MEXICO. THE NEXT
SIGNIFICANT SHORTWAVE TROUGH WAS WELL UPSTREAM YET OVER NW CANADA. AT
THE SFC...A RIDGE EXTENDED FROM THE MID MS VALLEY INTO THE SRN GREAT
LAKES RESULTING IN WSW FLOW THROUGH THE NRN LAKES. WEBCAMS AND MODEL
FCSTS SUGGEST THAT THE HEAVER LES BANDS HAD LIFTED MAINLY NORTH OF
CALUMET INTO THE N AND W PORTIONS OF KEWEENAW COUNTY. WAA 925-700 MB
WAA HELPED SUPPORT AN ARE OF LOW/MID CLOUDS AND A FEW FLURRIES FROM NRN
MN INTO NW WI AND WRN UPPER MI.
EXPECT THAT AS WINDS CONTINUE TO BACK THIS MORNING...ANY REMAINING
LES OVER THE TIP OF THE KEWEENAW WILL LIFT OUT INTO LAKE SUPERIOR
AROUND OR SLIGHTLY AFTER 12Z. SO...THE LES WARNING WILL BE ALLOWED
TO EXPIRE. OTHERWISE...NAM/RUC 925-700 MB RH FCST SUGGESTS THAT THE
CLOUDS SHOULD THIN OUT ENOUGH BY THIS AFTERNOON FOR AT LEAST SOME
SUNSHINE. TEMPS SHOULD CLIMB TO NEAR SEASONAL AVERAGES IN TO THE LOW
TO MID 20S.
THE MODELS WERE IN GOOD AGREEMENT WITH THE POSITION AND SPEED OF THE
NW CANADA CLIPPER SHRTWV MOVING TO JUST NW OF LAKE SUPERIOR BY
12Z/WED. THE GFS...AS IS OFTEN THE CASE WAS MORE AGGRESSIVE IN
SPREADING PCPN EASTWARD THROUGH UPPER MICHIGAN LATE TONIGHT COMPARED
TO THE NAM WHICH BARELY BRINGS ANY QPF TO THE WEST BEFORE 12Z.
ALTHOUGH THE DRY AIRMASS MAY DELAY THE ARRIVAL OF LIGHT SNOW AT THE
SURFACE...THE QVECTOR CONV AHEAD OF THE SHRTWV AND UPPER LEVEL DIV
WITH THE LEFT EXIT OF THE 250-300 MB JET STILL SHOULD BE ENOUGH FOR
LIKELY POPS OVER THE FAR WEST AND CHANCE POPS OVER THE REST OF THE
WEST HALF. SNOW AMOUNTS WILL BE LIGHT AS ONLY A FEW HUNDREDTHS QPF
SUPPORTS ACCUMULATIONS OF ONLY AROUND A HALF INCH OR LESS.
.LONG TERM...(WEDNESDAY THROUGH MONDAY)
ISSUED AT 500 AM EST TUE JAN 15 2013
LONG TERM PERIOD WILL BE DOMINATED BY NORTHWEST FLOW ALOFT AS AN
UPPER LOW SPINS NEAR HUDSON BAY. THIS WILL LEAD TO A SERIES OF
CLIPPER SYSTEMS AND ASSOCIATED COLDER AIR AND LAKE EFFECT ON THE
BACK SIDE.
THE FIRST SYSTEM WILL BE MOVING THROUGH AT THE START OF THE LONG
TERM PERIOD. THIS WAVE...CURRENTLY ROUNDING THE UPPER RIDGE ALONG
THE WESTERN COAST OF NORTH AMERICA...WILL BE SLIDING ACROSS LAKE
SUPERIOR WEDNESDAY MORNING. AT THE SURFACE...A COLD FRONT WILL BE
STRETCHED FROM A LOW IN SOUTHERN HUDSON BAY AND BE SWEEPING THROUGH
THE CWA THROUGH EARLY AFTERNOON. THE WIDESPREAD MOISTURE IS ACROSS
THE NORTH HALF OF THE CWA...WHILE A THIN RIBBON OF DEEP MOISTURE
MOVES ACROSS THE CWA LATE TONIGHT AND WEDNESDAY MORNING. ALTHOUGH
IT APPEARS THE SYSTEM WILL BE FIGHTING DRY LOW LEVEL AIR TO
START...MOST OF THE CWA SHOULD SEE A PERIOD OF LIGHT SNOW OR
FLURRIES. HIGH RES MODELS REALLY PICKING UP ON THE DRIER
AIR FOR THE CENTRAL CWA AND LIMITING QPF...SO WILL CONTINUE THAT
IDEA IN THE POPS AND SNOW AMOUNTS. BEST CHANCES FOR OVER AN INCH
WILL BE OVER THE WESTERN CWA AND EAST OF MUNISING.
BEHIND THIS FRONT...A PERIOD OF LAKE EFFECT IS EXPECTED WEDNESDAY
AFTERNOON INTO THURSDAY NIGHT. COLD AIR QUICKLY SURGES IN FROM THE
NORTHWEST ON WEDNESDAY AFTERNOON AND EVENING ACROSS THE
CWA...REACHING -25C BY 12Z THURSDAY. THIS PUTS MUCH OF THE CLOUD
LAYER ABOVE THE DGZ AND SHOULD LEAD TO LOWER SNOW RATIOS. WITH THAT
BEING SAID...STILL LOOKS LIKE VERY HIGH LAKE INDUCED EQL
VALUES...AROUND 10KFT...AND CAPE VALUES AROUND 900 J/KG. THERE IS
VERY DRY AIR ABOVE THE ACTUAL INVERSION AROUND 5KFT...SO WONDERING
IF THAT COMBINED WITH THE LOWER SNOW RATIOS WILL KEEP SNOWFALL
AMOUNTS FROM BEING TOO HEAVY WEDNESDAY NIGHT INTO THURSDAY.
ONE OTHER TREND TO MENTION IS THE IDEA OF A SURFACE TROUGH
LINGERING OVER EASTERN LAKE SUPERIOR LATE WEDNESDAY NIGHT AND
POTENTIALLY DEVELOPING INTO A WEAK LOW ON THURSDAY. EVEN THE COARSE
MODELS ARE STARTING TO SHOW THIS...WHICH IF IT OCCURS...MAY HELP
FOCUS AN AREA OF CONVERGENCE IN EASTERN ALGER AND LUCE COUNTIES FOR
HEAVIER SNOW. HIGH PRESSURE RIDGE SLIDES SOUTH OF THE AREA THURSDAY
AFTERNOON INTO THURSDAY NIGHT...WHICH WILL LEAD TO BACKING WINDS
AHEAD OF THE NEXT CLIPPER THAT WILL AFFECT THE AREA ON FRIDAY. THIS
WILL LEAD TO DRIER AIR ALOFT AND WARMING H850 TEMPS...WHICH
STRENGTHENS THE INVERSION TO AROUND 6KFT WHILE ALSO PUSHING THE DGZ
BACK INTO THE CLOUD LAYER. IN ADDITION...WITH THE WINDS LIKELY
BACKING MORE TO THE WEST...EXPECT THE LAKE EFFECT TO BE CONFINED TO
THE WESTERN CWA AND RIGHT ALONG THE SHORELINE OVER THE EAST IN THE
EVENING.
LOOKING AT CIPS ANALOG GUIDANCE...THE BEST FIT FOR THIS PERIOD IS
THE DECEMBER 10-11 1980 PERIOD...WHICH CORRELATES VERY WELL IN
H850 TEMPS ALTHOUGH THE SURFACE HIGH TO THE SOUTHWEST MAY BE
SLIGHTLY CLOSER TO THE CWA. 72-HR SNOWFALL AMOUNTS DURING THAT
PERIOD WERE GENERALLY IN THE 4-12 INCH RANGE...WHICH LENDS
CONFIDENCE TO THE GOING FORECAST THOUGHTS. IN ADDITION...LOOKING AT
PROBABILITIES FROM THE TOP 15 ANALOGS THEY SHOW A SIMILAR IDEA
FOR SNOW AMOUNTS...EVEN THOUGH THE MEAN H850 TEMPS ARE A LITTLE
WARMER THAN CURRENTLY EXPECTED. WILL CONTINUE TO MENTION MODERATE
SNOW IN THE HWO...SINCE SOME LOCATIONS WILL PROBABLY NEED LAKE
EFFECT SNOW ADVISORIES...DUE TO ADDITIONAL REDUCED VISIBILITIES WITH
THE FINER SNOWFLAKES AND SOME BLOWING SNOW. IN ADDITION...LOOKING AT
COOP TEMPERATURE OBSERVATIONS DURING THAT 1980 EVENING...THE GOING
IDEA OF HIGHS OF 10-15 AND LOWS AROUND ZERO LOOKS GOOD.
MODELS CONTINUE TO HAVE SUBTLE DIFFERENCES WITH THE CLIPPER
SYSTEM...BUT THE OVERALL IDEA OF IT TRAVERSING THE CWA SEEMS
REASONABLE FOR FRIDAY. SNOW LOOKS TO ARRIVE DURING THE LATER PART
OF THURSDAY NIGHT AND INTO FRIDAY...UNDER THE STRONG H850 WAA. AT
THIS POINT...LOOKS LIKE ANOTHER DUSTING OF AROUND AN INCH OF SNOW.
THE WARMING SOUTHWEST FLOW WILL ALSO PUSH HIGHS 10-15 DEGREES
WARMER THAN THURSDAY.
AFTER THAT...CONFIDENCE QUICKLY DROPS IN THE FORECAST...AS THERE
ARE VARYING TIMES AT WHICH THE NEXT STRONGER SHORTWAVE ARRIVES.
00Z GFS IS FASTER AND ARRIVES EARLY SATURDAY...WHILE THE 00Z
ECMWF/GEM HAVE IT ARRIVING SATURDAY AFTERNOON. FOR THIS TIME OF THE
YEAR...THESE DIFFERENCES MAKE A HUGE DIFFERENCES FOR THE FORECAST
DUE TO WIND FIELDS...H850 TEMPS...AND POTENTIAL FOR LAKE EFFECT.
WILL JUST GO WITH A GENERAL CHANCE POPS FOR THE ENTIRE AREA...WITH
THE HIGHEST VALUES NEAR LAKE SUPERIOR.
ONCE THIS WAVE DEPARTS...LOOKS TO BE ANOTHER PERIOD OF MULTI-BAND
LAKE EFFECT FOR THE NORTHWEST WIND LAKE EFFECT AREAS SUNDAY INTO
MONDAY. AFTER BECOMING DISRUPTED SOME WITH THE LAST SHORTWAVE...THE
UPPER TROUGH WILL AGAIN REESTABLISH ITSELF OVER THE GREAT LAKES
THROUGH THE FIRST PART OF NEXT WEEK. H850 TEMPS WILL AGAIN BE AROUND
-25C AND LEAD TO PERIODS OF MODERATE LAKE EFFECT SNOW. WILL BUMP
POPS UP BASED OFF LOCAL LAKE EFFECT CLIMATOLOGY GRIDS TO HIGH
CHANCE OR LOW LIKELY VALUES FOR NORTHWEST WIND LOCATIONS.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z WEDNESDAY MORNING)
ISSUED AT 701 AM EST TUE JAN 15 2013
AN AREA OF MID CLOUDS WITH MAINLY VFR CIGS WILL COVER THE AREA EARLY
TODAY. THERE MAY BE A BRIEF PERIOD OF MVFR CIGS AT IWD.
HOWEVER...EXPECT THE CIGS TO DISSIPATE BY AFTERNOON WITH DRIER AIR
MOVING IN FROM THE WEST. AS A SHORTWAVE TROUGH AND LOW PRESSURE
SYSTEM APPROACH THE AREA FROM THE NORTHWEST...SOUTHWEST WINDS WILL
INCREASE TODAY AND TONIGHT. ALTHOUGH WINDS WILL BE SOMEWHAT
DECOUPLED...EXPECT GUSTY CONDITIONS MAY LIMIT LLWS POTENTIAL. SOME
LIGHT SNOW MAY ALSO MOVE IN LATE OVER THE WEST BUT IS NOT EXPECTED TO
REDUCE CONDITIONS INTO THE MVFR RANGE BEFORE 12Z/WED.
&&
.MARINE...(FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 500 AM EST TUE JAN 15 2013
SOUTHWEST WINDS WILL INCREASE THIS AFTERNOON AND TONIGHT AHEAD OF
AN APPROACHING COLD FRONT. THIS WILL PRODUCE GALES TO 35-40KTS AND
WILL CONTINUE THE GALE WARNING FOR TONIGHT INTO WEDNESDAY. WINDS
WILL SHIFT TO THE WEST AND THEN NORTHWEST AND GUST TO 40KTS DURING
THE DAY WEDNESDAY BEHIND THE FRONT. NORTHWEST WINDS OF 15-30KTS
WILL CONTINUE WEDNESDAY NIGHT INTO THURSDAY...WITH OCCASIONAL GALE
FORCE GUSTS TO 35KTS. A SERIES OF CLIPPER SYSTEMS ARE EXPECTED TO
MOVE THROUGH ON FRIDAY AND AGAIN ON SATURDAY. THIS WILL DISRUPT THE
WINDS SOME DURING THOSE PERIODS...WITH NORTH-NORTHWEST WINDS TO
30KTS AGAIN EXPECTED SATURDAY NIGHT.
FINALLY...HEAVY FREEZING SPRAY IS EXPECTED WEDNESDAY NIGHT INTO
THURSDAY EVENING OVER MUCH OF LAKE SUPERIOR.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
GALE WARNING FROM 7 PM THIS EVENING TO 7 PM EST WEDNESDAY FOR
LSZ264>267.
GALE WARNING FROM 7 PM EST /6 PM CST/ THIS EVENING TO 1 PM EST
/NOON CST/ WEDNESDAY FOR LSZ162-263.
GALE WARNING FROM 1 AM TO 7 PM EST WEDNESDAY FOR LSZ244-245-
249>251.
GALE WARNING FROM 1 PM TO 7 PM EST WEDNESDAY FOR LSZ248.
GALE WARNING FROM 1 AM EST /MIDNIGHT CST/ TO 1 PM EST /NOON CST/
WEDNESDAY FOR LSZ240>243.
LAKE MICHIGAN...
GALE WARNING FROM 4 AM TO 1 PM EST WEDNESDAY FOR LMZ221-248-250.
&&
$$
SHORT TERM...JLB
LONG TERM...SRF
AVIATION...JLB
MARINE...SRF
AREA FORECAST DISCUSSION
NWS GAYLORD MI
649 AM EST TUE JAN 15 2013
.SYNOPSIS...
ISSUED AT 346 AM EST TUE JAN 15 2013
SEVERAL AREAS OF LOW PRESSURE AND COLD FRONTS WILL CROSS NORTHERN
MICHIGAN OVER THE NEXT SEVERAL DAYS. THIS WILL PRODUCE PERIODS OF
LAKE EFFECT AND LAKE ENHANCED SNOW SHOWERS...WHICH WILL PRIMARILY
AFFECT EASTERN UPPER AND NORTHWEST LOWER MICHIGAN.
&&
.UPDATE...
ISSUED AT 639 AM EST TUE JAN 15 2013
BIG UPDATES EARLY THIS MORNING...AS THE STRATO CU OFF THE LAKES
HAS RAPIDLY ERODED...LEAVING CLEARING SKIES MOST AREAS...WITH ONLY
SOME SCATTERED FLURRIES. WITH NO DISCERNIBLE MID LEVEL CLOUD
UPSTREAM...OUTSIDE OF A SMALL AREAS IN NORTH CENTRAL
WISCONSIN...WILL DISREGARD NAM/GFS TRAPPED IN SHALLOW STRATO CU
MOSTLY CLOUDY SKY FOR THE DAY. RATHER...WILL OPT TO KEEP SKIES ON
THE CLEARER SIDE FOR THE DAY. THIS AGREED UPON BY LATEST RUC DATA.
AS WINDS INCREASE TONIGHT...MAYBE SOME ADDITIONAL MOISTURE FLUX
OFF THE LAKES...BUT EVEN HERE...DATA SUGGESTS THAT THE ATMOSPHERE
DRIES OUT LATE...PRIOR TO NEXT UPSTREAM CLIPPER/COLD FRONT SET FOR
WEDNESDAY.
&&
.SHORT TERM...(TODAY THROUGH TONIGHT)
ISSUED AT 346 AM EST TUE JAN 15 2013
EARLY MORNING REGIONAL ANALYSIS SHOWS HIGH PRESSURE STRETCHED OUT
ACROSS THE WESTERN LAKES ON FRONT SIDE OF POSITIVELY TILTED DEEP MID
LEVEL TROUGH AXIS EXTENDING FROM HUDSON BAY DOWN TO NEAR THE FOUR
CORNERS. LIGHT WSW FLOW CONTINUES TO ROTATE AROUND NORTH EDGE OF
SURFACE RIDGE AXIS ACROSS THE NORTHERN LAKES. THIS...COMBINED WITH
MORE THAN SUFFICIENT DELTA T/S (RAP ANALYSIS SHOWS H85 TEMPS IN THE
NEGATIVE MID TEENS) AND SLIGHT UPTICK IN LOW LEVEL MOISTURE...HAS
KICKED OFF GENERALLY LIGHT LAKE INDUCED SNOWS ACROSS NORTHWEST LOWER
MICHIGAN. NICE FLUFF FACTOR...HOWEVER...WITH LAKE INDUCED MOISTURE
AXIS REMAINING PEGGED IN THE DGZ...AS NOTED BY LARGE DENDRITIC
CONGLOMERATES FALLING HERE AT THE OFFICE. NO REPORTS YET...BUT NO
DOUBT AT LEAST SOME LIGHT ACCUMULATIONS OCCURRING UNDER WEAK BANDING
STRUCTURES. FORECAST CONCERNS THROUGH THE SHORT TERM CONTINUE TO
CENTER ON MESOSCALE LAKE SNOW TRENDS.
MARGINAL LAKE PROCESSES TO CONTINUE THROUGH TODAY AS SUFFICIENT
LAKE/AIR TEMPERATURE DIFFERENCE REMAINS PARTIALLY OFFSET BY LOW
INVERSION HEIGHTS AND LIMITED MOISTURE. MODEL DERIVED SOUNDINGS
CONCUR...WITH NOTED INVERTED-V DEVELOPMENT IN SURFACE BASED
ENVIRONMENT AS UPSTREAM DRY SURGE REPLACES CURRENT UPTICK IN LOW
LEVEL MOISTURE. "BEST" ACTIVITY EXPECTED EARLY ON THIS MORNING IN
FAVORED W TO WSW FLOW REGIMES OF NORTHWEST LOWER...WITH PERHAPS AN
ADDITIONAL INCH OR TWO UNDER THE MORE PERSISTENT BANDS. MUCH LIKE
YESTERDAY...EXPECT A DOWNWARD TREND IN BOTH INTENSITY AND COVERAGE
THROUGH THE DAY AS FLOW ONCE AGAIN BACKS AROUND TO SOUTHWEST BY THIS
AFTERNOON. POSSIBLY THINGS MAY END ALL TOGETHER (ALSO LIKE
YESTERDAY)...BUT DON`T WANT TO GO THIS OPTIMISTIC JUST YET. EITHER
WAY...NOT A BIG DEAL THIS AFTERNOON WITH ANY SNOW AMOUNTS LIKELY
REMAINING VERY LIGHT. NOT TOO SHABBY OF A DAY AWAY FROM THE FAVORED
LAKE PRONE AREAS OF NORTHWEST LOWER/SOUTHERN PORTIONS OF EASTERN
UPPER...WITH PARTLY TO MOSTLY CLOUDY SKIES AND TEMPERATURES IN THE
20S.
STORY REMAINS UNCHANGED THROUGH THIS EVENING WITH MARGINAL
INSTABILITY KICKING OFF SCATTERED LIGHT SNOW SHOWERS IN SOUTHWEST
FLOW AREAS. ALBERTA CLIPPER/COLD FRONT APPROACH THE WESTERN LAKES
LATE...WITH TRENDS SUPPORTING ATTENDANT MOISTURE AXIS NOT REACHING
OUR AREA UNTIL AFTER SUNRISE. WEAK PRE-FRONTAL WAA AND CONTINUOUS
FEED OF LOW LEVEL DRY AIR SHOULD CONTINUE TO SUBSTANTIALLY HINDER
LAKE PROCESSES THROUGH THE OVERNIGHT...DESPITE STEADY UPTICK IN
OVER-WATER WIND SPEEDS. EXPECT ANY SNOWFALL AMOUNTS TO REMAIN UNDER
AN INCH. UPTICK IN WINDS UNDER INCREASING PRESSURE GRADIENT REGIME
WILL OFFSET PARTLY TO MOSTLY CLEAR SKIES ELSEWHERE...NOT ALLOWING
TEMPERATURES TO DROP TOO MUCH. INHERITED LOW IN THE TEENS AND 20S
LOOK GREAT.
.LONG TERM...(WEDNESDAY THROUGH MONDAY)
ISSUED AT 346 AM EST TUE JAN 15 2013
WEDNESDAY AND WEDNESDAY NIGHT...UPPER LEVEL TROUGHING WILL BE
SITUATED OVER THE NRN GREAT LAKES...SHARPENED BY SHORTWAVE ENERGY
DIVING INTO THE REGION. THE ASSOCIATED CLIPPER/LOW PRESSURE WILL
PASS THROUGH ONTARIO...WITH A FAIRLY STRONG COLD FRONT TO CROSS
NRN MICHIGAN WEDNESDAY NIGHT. SW WINDS AHEAD OF THE FRONT WILL
GRADUALLY SHIFT AROUND TO OUT OF THE NW BY THURSDAY MORNING.
ENHANCED MOISTURE WITH THE FRONT WILL BRING SOME LIGHT SYNOPTIC
SNOWS WEDNESDAY...ENHANCED TO A MARGINAL DEGREE BY H8 TEMPS OF
-8C. NOT IMPRESSED WITH THE SNOWFALL INTENSITIES...AS INVERSION
HEIGHTS ONLY BRIEFLY RISE TO 5KFT...WITH WSW FLOW POINTING BEST
SNOWS ALONG FAR NW LOWER AND INTO EASTERN UPPER. LOWERED SNOWFALL
AMOUNTS BASED ON TURNING WINDS...AND ONLY A BRIEF PERIOD OF MORE
MODERATE ACTIVITY WITH THE FRONT. SECONDARY SHORTWAVE ENERGY AND
DEEPER MOISTURE WILL ENHANCE SNOW SHOWERS AT NIGHT...WHILE H8
TEMPS PLUMMET TO -22C NORTH/-16C SOUTH. AGAIN...WINDS ARE SHIFTING
OVER TIME...WITH INVERSION HEIGHTS 5KFT NORTH TO 4000 FEET SOUTH.
WHILE IT WILL OBVIOUSLY BE SNOWING FOR CATEGORICAL POPS...ACCUMS
NOT EXPECTED TO BE THRILLING AT 1-3" IN THE FAVORED AREAS FOR BOTH
OF THESE PERIODS (CHIP COUNTY IN EASTERN UPPER AND IN THE HIGHER
TERRAIN OF INTERIOR NRN LOWER AROUND GAYLORD. HIGHS AROUND 30F
WEDNESDAY WILL FALL INTO THE SINGLE DIGITS AND TEENS WEDNESDAY
NIGHT.
THURSDAY THROUGH FRIDAY...MOISTURE/COLD AIR REMAIN SUFFICIENT
THROUGH THURSDAY NIGHT FOR CONTINUED LIGHT LAKE EFFECT
ACCUMULATIONS. WNW WINDS WILL BE BACKING WITH TIME WITH LESS
MOISTURE. INVADING HIGHER PRESSURE WILL ALSO TURN THE WINDS MORE
ANTICYCLONIC THROUGH THEN WITH MAYBE A COUPLE OF INCHES IN SPOTS
IN NRN CHIP COUNTY AND FAR NW LOWER. THEN...THE NEXT CLIPPER
ARRIVES FRIDAY WITH STRONGER SW FLOW AND WARMING EXPECTED THROUGH
THE DAY FRIDAY. A WING OF WARM FRONTAL SYNOPTIC SNOWS...AND
BRIEF SW FLOW ENHANCEMENT FOR FRIDAY MORNING BEFORE THE
TEMPERATURES RISE/INVERSION HEIGHTS FALL.
FRIDAY NIGHT THROUGH EARLY NEXT WORK WEEK...LOW PRESSURE AND YET
ANOTHER COLD FRONT...SLOW MOVING...SLIDE IN ACROSS NRN MICHIGAN.
BEST LOW LEVEL CONVERGENCE AND RESULTING SNOWFALL WILL BE IN
EASTERN UPPER FRIDAY NIGHT INTO EARLY SATURDAY...BEFORE SHIFTING
SOUTH INTO NRN LOWER LATE SATURDAY AND SATURDAY NIGHT. WIND
DIRECTIONS ARE TOO UNCERTAIN AT THIS POINT...BUT DATA RIGHT NOW
SUGGESTS POOR NE FETCH ACROSS EASTERN UPPER...WITH BETTER NW FLOW
ACROSS NW LOWER FOR THE BEST ACCUMULATIONS. THE ASSOCIATED WAVE
ALOFT IS MORE DEFINED WITH EXPECTED MODEST DEEP LAYER -DIVQ. BY
SUNDAY...WINDS BACK AROUND OUT OF THE NW FOR EASTERN UPPER TO GET
BACK INTO THE LAKE EFFECT...ALONG WITH NW LOWER. SNOWS SUNDAY
NIGHT POSSIBLY ENHANCED YET AGAIN WITH NEXT IN THE SERIES OF
CLIPPERS/WAVES/SYNOPTIC SNOWFALL. LAKE EFFECT CONTINUES BEHIND
THIS CLIPPER INTO MONDAY AND TUESDAY.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z WEDNESDAY MORNING)
ISSUED AT 639 AM EST TUE JAN 15 2013
LOW LEVEL MVFR CIGS HAVE RAPIDLY ERODED...AS DRIER AIR HAS
OVERPOWERED THE LAKE EFFECT. COULD BE A BRIEF PERIOD OR TWO THAT
THESE CLOUDS WILL BE ABLE TO DEVELOP TODAY...BUT SOME UNCERTAINTY
DOES EXIST. LATEST SATELLITE AND RAPID UPDATE DATA SUGGEST THE
CLEARER SCENARIO IS THE ONE TO FOLLOW. MAYBE THIS CLOUD CAN
BRIEFLY FIRE UP THIS EVENING AS SW/WSW WINDS INCREASE IN ADVANCE
OF A CLIPPER SYSTEM/COLD FRONT SET FOR WEDNESDAY...BUT AGAIN...AIR
MASS DRIES LATE IN THE PERIOD. PREVAILING CONDITIONS EXPECTED TO
BE VFR. AS WINDS INCREASE LATE TONIGHT...WIND SHEAR ISSUES
INCREASE...BUT BELIEVE AT THIS POINT...THERE WILL BE ENOUGH OF A
SFC WIND TO PREVENT THE INTRODUCTION OF LLWS INTO THE FORECAST.
&&
.MARINE...
ISSUED AT 346 AM EST TUE JAN 15 2013
COMBINATION OF REMNANT OVER-WATER INSTABILITY AND TIGHTENING
PRESSURE GRADIENT AHEAD OF APPROACHING CLIPPER SYSTEM WILL RESULT
IN A QUICK INCREASE OF SOUTHWEST WINDS ACROSS NORTHERN LAKE
MICHIGAN AND THE STRAITS LATER THIS AFTERNOON...CONTINUING THROUGH
WEDNESDAY. GALES SEEM A CERTAINTY ACROSS CURRENT WATCH AREA
TONIGHT THROUGH WEDNESDAY...SO WILL UPGRADE AT THIS ISSUANCE. GALE
CONDITIONS SEEM INCREASINGLY POSSIBLE ALONG THE THE NORTHERN
PORTION OF LAKE HURON ON WEDNESDAY. STILL SOME LINGERING
UNCERTAINTY... ESPECIALLY ON TIMING. WILL ISSUE A GALE WATCH
WEDNESDAY INTO WEDNESDAY EVENING TO COVER THIS POTENTIAL.
THEREAFTER...A SEASONABLY ACTIVE PERIOD OF WEATHER IS EXPECTED
RIGHT ON INTO NEXT WEEKEND...WITH SEVERAL CLIPPER SYSTEMS CROSSING
THE WATERS... FOLLOWED BY PERIODS OF LAKE EFFECT SNOW. MORE ROUNDS
OF SMALL CRAFT ADVISORY WINDS ARE LIKELY THROUGHOUT THE LATE WEEK
AND WEEKEND.
&&
.APX WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
LH...GALE WARNING FROM 7 PM THIS EVENING TO 4 PM EST WEDNESDAY FOR
LHZ345.
GALE WATCH FROM WEDNESDAY MORNING THROUGH WEDNESDAY EVENING FOR
LHZ346-347.
LM...GALE WARNING FROM 7 PM THIS EVENING TO 4 PM EST WEDNESDAY FOR
LMZ323-341-342-344>346.
LS...NONE.
&&
$$
UPDATE...SD
SYNOPSIS...SD
SHORT TERM...MB
LONG TERM...SD
AVIATION...SD
MARINE...MB
AREA FORECAST DISCUSSION
NWS NEWPORT/MOREHEAD CITY NC
730 AM EST TUE JAN 15 2013
.SYNOPSIS...
A COLD FRONT MOVING SOUTH OVER THE AREA EARLY THIS MORNING WILL
STALL OVER SOUTHERN SECTIONS THIS AFTERNOON AND EVENING. THE FRONT
WILL RETURN TO THE NORTH AS A WARM FRONT TONIGHT AND
WEDNESDAY...THEN CROSS THE AREA AS A COLD FRONT WEDNESDAY NIGHT. LOW
PRESSURE WILL PASS TO THE SOUTH OF THE AREA THURSDAY NIGHT AND
FRIDAY. HIGH PRESSURE WILL BUILD IN SATURDAY AND SUNDAY. A DRY COLD
FRONT WILL MOVE THROUGH THE AREA MONDAY.
&&
.NEAR TERM /TODAY/...
AS OF 700 AM TUESDAY...COLD FRONT HAS PUSHED TO S COAST WITH COOLER
TEMPS AND WDSPRD LOW CLOUDS SPREADING OVER ALL LAND AREAS. LATEST
RUC13 AND HRRR HAVE BEST HANDLE ON FRONTAL POSITION AND HAVE UPDATED
WITH BLEND. 3 HRLY PRES RISES HAVE DIMINISHED AND EXPECT FRONT TO
STALL ALONG S COAST REST OF DAY. THIS WILL ALLOW LOW CLOUDS TO LIFT
OVER SRN SECTIONS AND TEMPS TO WARM INTO 60S...WHILE CLOUDS HOLD NRN
2/3 OF AREA WITH TEMPS HOLDING IN 50S.
/PREVIOUS DISCUSSION/
AS OF 345 AM TUESDAY...COLD FRONT IS BACKDOORING ACROSS AREA EARLY
THIS MORNING WITH WIDESPREAD LOW CLOUDINESS DEVELOPING AS LOW LVL
WINDS BECOME NRLY. MODELS IN GENERAL AGREEMENT ON FRONT STALLING
NEAR HAT-EWN-DPL LINE THIS MORNING AND REMAINING NEARLY STNRY
THROUGH AFTN. MAIN THREAT OF PCPN WILL BE OVER NRN SECTIONS WITH
BETTER ISENTROPIC LIFT WHILE SRN COASTAL SECTIONS WILL SEE ISOLATED
SHOWER THREAT. WILL CONTINUE POP RANGE FROM 20 SOUTH TO NEAR 40-50
NORTH. TEMP FCST A CHALLENGE WITH BNDRY STALLED OVER AREA AND
PERSISTENT LOW CLOUDS LIMITING HEATING OVER NRN HALF OF AREA. WENT
WITH BLEND OF PREVIOUS FCST AND LATEST MOS BLEND...RESULTING IN HIGH
TEMPS RANGING FROM LOWER 50S ON NRN OBX TO NEAR 70 SRN-MOST
SECTIONS.
&&
.SHORT TERM /TONIGHT/...
AS OF 345 AM TUESDAY...SFC FRONT EXPECTED TO PUSH S OVER SRN
SECTIONS EARLY THIS EVENING...THEN RETURN N AS A WARM FRONT
OVERNIGHT AS LOW PRES DEVELOPES TO THE WEST. MODELS CONTINUE TO
INDICATE MAIN PCPN THREAT REMAINING W AND N OF AREA...BUT DO
INDICATE SOME LIGHT QPF PSBL MOST OF AREA WITH BNDRY RETURNING
N...THUS KEPT LOW CHC POPS..20 S/30 N...OVER AREA. PROBLEMATIC TEMP
FCST FOR THIS PERIOD AS WELL DUE TO BNDRY. MIN TEMPS WILL LIKELY BE
DURING EVENING HOURS OVER SRN SECTIONS WITH INCREASING TEMPS
EXPECTED OVERNIGHT AS WARM FRONT LIFTS N. LEANED TO COOLER NAM MOS
WHICH WAS GENERALLY IN LINE WITH PREVIOUS FCST.
&&
.LONG TERM /WEDNESDAY THROUGH MONDAY/...
AS OF 315 AM TUE...NO SIGNIFICANT CHANGES NEEDED TO ONGOING
FORECAST AT THIS TIME. CONTINUED TO RELY HEAVILY ON THE ECMWF AND HPC
THROUGH THE LONG TERM AS IT HAS BEEN THE MOST CONSISTENT.
FRONTAL BOUNDARY WILL REMAINED STALLED JUST TO THE W OF THE CWA
WED. EASTERN NC WILL REMAIN IN THE WARM SECTOR AS MOIST S/SWLY
FLOW CONTINUES RESULTING IN ANOTHER DAY OF ABOVE NORMAL
TEMPERATURES GENERALLY IN THE LOWER 70S IN THE SW CWA AND MID TO
UPPER 60S ELSEWHERE. DEEPEST MOISTURE AND BEST SUPPORT REMAINS TO THE
W/NW...SO WILL CONTINUE TO CAP POPS AT CHANCE FOR THE INLAND
COUNTIES. THE COLD FRONT WILL FINALLY MOVE THROUGH THE AREA WED
NIGHT AS THE LOW PUSHES OFF THE MID-ATLANTIC COAST. BEST MOISTURE
AND FORCING WILL REMAIN N OF THE AREA WED NIGHT AND NOT EXPECTING
A SIGNIFICANT AMOUNT OF QPF WITH LESS THAN A QUARTER INCH
EXPECTED.
A MUCH COLDER AIRMASS WILL BE IN PLACE ACROSS THE REGION THU WITH
LOW LEVEL THICKNESSES AROUND 40M LOWER ALLOWING FOR HIGHS 10-15
DEGREES COOLER THAN WED WITH HIGHS IN THE 50S. EXPECT DRY CONDITIONS
WITH SHORTWAVE RIDGING BUILDING ALOFT. WILL BE WATCHING THE
PROGRESSION OF THE LOW PRES SYSTEM ACROSS TEXAS LIFT ACROSS THE DEEP
SOUTH AND OFF THE NC/SC COAST THU NIGHT AND FRI. MODELS NOT IN BEST
AGREEMENT WITH THE TRACK AND INTENSITY OF THIS LOW WHICH WILL
ULTIMATELY DETERMINE THE AMOUNT OF PCPN ACROSS THE REGION. CONTINUE
TO SIDE WITH THE ECMWF WHICH IS THE WEAKER AND MORE OFFSHORE
SOLUTION. WILL CONTINUE HIGH CHANCE TO LIKELY POPS THU NIGHT AS
SHORTWAVE MOVES THROUGH.
COLD HIGH PRES WILL BE BUILDING IN FROM THE PLAIN STATES AND PCPN
MAY TRANSITION TO A RAIN/SNOW MIX AS THE PCPN WINDS DOWN THU NIGHT
BUT WITH THE VERY WARM ANTECEDENT CONDITIONS WE`VE HAD THIS PAST
WEEK DO NOT THINK THERE WILL BE ANY IMPACTS. MORE THAN LIKELY IT
WILL BE A TYPICAL CASE OF COLD AIR CHASING THE MOISTURE. SLOWER
AND MORE AMPLIFIED MODEL SOLUTIONS CONTINUE PCPN INTO EARLY FRI
BUT AM FOLLOWING THE MORE PROGRESSIVE ECMWF AT THIS TIME. UPPER
TROUGHING CONTINUES ACROSS THE EASTERN CONUS OVER THE WEEKEND.
TEMPS EXPECTED TO BE A LITTLE BELOW NORMAL IN THE M/U40S
FRI...THEN THICKNESSES RECOVER OVER THE WEEKEND WITH HIGHS IN THE
M/U50S. A DRY COLD FRONT IS THEN PROGGED TO PUSH THROUGH THE
REGION SUN NIGHT WITH COLD HIGH PRES BUILDING IN FROM THE N MONDAY
BRINGING HIGHS IN THE L/M50.
&&
.AVIATION /12Z TUESDAY THROUGH SATURDAY/...
SHORT TERM /THROUGH 12Z WEDNESDAY/...
AS OF 630 AM TUESDAY...COLD FRONT HAS PUSHED S OF ALL TAF
SITES...WITH WDSPRD IFR CIGS DEVELOPING IN COOL SECTOR. FRONT WILL
STALL OVER SRN SECTIONS TODAY...WITH CIGS EXPECTED TO LIFT TO MVFR
WITH PERIOD OF VFR PSBL FOR KOAJ. IFR WILL RETURN THIS EVENING...BUT
SOME IMPROVE EXPECTED OVERNIGHT WITH FRONT LIFTING N AGAIN. IFR
LIKELY AT KPGV ENTIRE TAF PERIOD.
LONG TERM /WEDNESDAY THROUGH SATURDAY/...
AS OF 315 AM TUE...SUB-VFR CONDITIONS WILL BE POSSIBLE
WED...MAINLY FOR PGV/ISO...AS FRONTAL BOUNDARY REMAINS STALLED
JUST INLAND. THE COLD FRONT WILL MOVE THROUGH THE TERMINALS WED
NIGHT WITH SCT SHOWERS AND NLY WINDS DEVELOPING BEHIND IT. RAIN
WILL RETURN THU NIGHT WITH PERIODS OF SUB-VFR LIKELY. PREDOMINATE
VFR CONDITIONS SHOULD RETURN FRI AND SAT AS HIGH PRESSURE BUILDS
OVER THE AREA.
&&
.MARINE...
SHORT TERM /THROUGH TONIGHT/...
AS OF 700 AM TUESDAY...COLD FRONT HAS PUSHED TO SRN WATERS EARLY
THIS MORNING WITH NE SURGE OF 15-20 KTS OVER PORTIONS OF CENTRAL
WATERS AND PAMLICO SOUND. FRONT EXPECTED TO STALL OVER SRN WATERS
REST OF DAY WITH WINDS DECREASING TO LESS THAN 15 KT. FRONT WILL
RETURN N AS WARM FRONT OVERNIGHT...WITH SW WINDS INCRREASING TO
15-20 KTS LATE TONIGHT OVER SRN AND CENTRAL WATERS AS LOW PRES
DEVELOPES TO W.
WW3 REMAINS CONSISTENT WITH PREVIOUS FCST WITH SEAS MAINLY 2-4 FT.
LONG TERM /WEDNESDAY THROUGH SATURDAY/...
AS OF 315 AM TUE...A COLD FRONT WILL REMAIN JUST INLAND
WED...RESULTING IN MODERATE SWLY FLOW ACROSS THE WATERS. MARGINAL
SCA CONDITIONS POSSIBLE FOR THE CENTRAL WATERS WED AFTERNOON...BUT
THINK IT COULD BE DIFFICULT FOR SW WINDS TO MIX WELL OVER THE COOLER
WATERS. AT THIS TIME STILL EXPECT WINDS 10-20KT AND SEAS 3-5FT. THE
FRONT WILL MOVE THROUGH THE WATERS WED NIGHT WITH NLY WINDS 10-15KT
DEVELOPING BEHIND IT. UNCERTAINTY STILL REMAINS FOR THU AND FRI WITH
DEVELOPMENT OF LOW PRESSURE SYSTEM TO THE SOUTH. NO SIG CHANGES MADE
TO PREVIOUS FORECAST AT THIS TIME...CONTINUED TO TREND WITH HPC AND
ECMWF. EXPECT NLY WINDS TO INCREASE THU NIGHT WITH SEAS BUILDING
INTO FRI. THOUGH UNCERTAINTY REMAINS...LIKELY TO SEE SCA CONDITIONS
DEVELOP THU NIGHT AND CONTINUE INTO FRI. CAPPED WINDS AT 25KT AND
SEAS AT 4-7FT. HIGH PRESSURE WILL BUILD EASTWARD ACROSS THE AREA FOR
FRI AND SAT. NE WINDS WILL SLOWLY SUBSIDE FRI BECOMING LIGHT SAT.
&&
.MHX WATCHES/WARNINGS/ADVISORIES...
NC...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS...JME
NEAR TERM...JBM
SHORT TERM...JBM
LONG TERM...SK/CQD
AVIATION...JBM/CQD
MARINE...JBM/CQD
AREA FORECAST DISCUSSION
NWS WILMINGTON NC
716 AM EST TUE JAN 15 2013
.SYNOPSIS...
ATLANTIC HIGH PRESSURE WILL PRODUCE UNSEASONABLY MILD CONDITIONS
INTO MID-WEEK. A COLD FRONT WILL MOVE SLOWLY THROUGH THE AREA LATE
WEDNESDAY. WEAK GULF COAST LOW PRESSURE WILL BRING A CHANCE OF
RAIN TO THE REGION THURSDAY NIGHT INTO FRIDAY. HIGH PRESSURE WILL
BUILD IN BEHIND THE COLD FRONT FOR THE WEEKEND. A DRY COLD FRONT
WILL MOVE ACROSS THE SOUTHEAST SUNDAY NIGHT.
&&
.NEAR TERM /THROUGH TONIGHT/...
AS OF 630 AM TUESDAY...A SNAKING COLD FRONT LYING NE-SW ACROSS
THE CAROLINAS WILL BASICALLY DROP TO THIS GENERAL VICINITY TODAY
BEFORE BECOMING ALIGNED WITH THE FLOW ALOFT. LOOKING AT 11-3.9
MICRON SAT IMAGERY TRENDS...INDICATES THIS FRONT CONTINUES TO MAKE
SOME PROGRESS TO THE SOUTHEAST. THIS WILL IMMEDIATELY HAVE
IMPLICATIONS TO THE CURRENT FORECAST IF THIS MOVEMENT DOES NOT
SLOW AND STALL.
THE WESTERN ATLANTIC RIDGING BOTH AT THE SFC AND ALOFT...WILL
CONTINUE TO PARTIALLY EXTEND ACROSS THE FORECAST AREA. MODELS QUITE
SIMILAR WITH THE STALLED COLD FRONT MEANDERING JUST WEST THROUGH
NORTH OF THE FORECAST AREA INTO TONIGHT. LATEST HRRR AND TO AN
EXTENT THE NAM/GFS...INDICATE THE FRONT TO REACH THE NORTHERN
PORTIONS OF THE ILM CWA TODAY BEFORE BACKING TO THE NORTH LATER
TONIGHT. WILL INDICATE ITS PARTIAL PASSAGE WITH A REFLECTION IN
THE WIND FIELD AND LOWERING OF THE TEMPS. WITH THE MAJORITY OF
THE PCPN ASSOCIATED WITH THIS FRONTAL SYSTEM OCCURRING AFTER ITS
PASSAGE AND NOT AHEAD OF IT...HAVE KEPT POPS TO A MINIMUM WITH
ONLY A SLIGHT CHANCE FOR RW-. WITH INSTABILITY LACKING IE. NEARLY
NONEXISTENT CAPE AND POSITIVE LI VALUES...THUNDER WILL REMAIN OUT
OF THE NEAR TERM FORECAST. FOR OVERALL TEMPS...HAVE STAYED WITH
THE HIGHER MODEL MOS GUIDANCE...WITH AN ADDITIONAL COUPLE OF
DEGREES ADDED ON ACROSS THE SOUTHERN PORTIONS OF THE ILM CWA.
&&
.SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/...
AS OF 230 AM TUESDAY...COLD FRONT WEST OF THE AREA AT THE START
OF THE PERIOD SLOWLY MOVES OFFSHORE LATE WED NIGHT. THIS ALLOWS
ONE LAST DAY OF TEMPERATURES WELL ABOVE CLIMO. INCREASING CLOUDS
AND ISOLATED AFTERNOON INSTABILITY SHOWERS MAY HOLD TEMPS DOWN A
LITTLE BIT...ESPECIALLY INLAND...BUT WIDESPREAD LOW 70S ARE STILL
ANTICIPATED. LOWS CONTINUE TO RUN WELL ABOVE CLIMO...LOWER 50S
ACROSS MUCH OF THE AREA.
FORECAST COMPLEXITY INCREASES WED NIGHT THROUGH THU NIGHT WITH A
SOUTHERN STREAM SYSTEM EXITING THE SOUTHWEST WED NIGHT AND MOVING
ACROSS THE GULF COAST THU. TIMING AND TRACK OF THE 5H SHORTWAVE
TROUGH AND RESULTING SURFACE WAVE REMAIN IN QUESTION. TREND IN
GUIDANCE HAS BEEN SHOWING THE SOUTHERN STREAM WAVE NEARLY CLOSED OFF
AS IT EMERGES FROM THE SOUTHWEST THEN OPENING UP BY THE TIME IT
MOVES INTO THE SOUTHEAST AND OFF THE EAST COAST. THIS LIMITS
CYCLOGENESIS ALONG THE BOUNDARY STALLED OFF THE COAST...KEEPING
SURFACE WAVE LITTLE MORE THAN WEAK LOW AT BEST. GUIDANCE IN FAIRLY
GOOD AGREEMENT TRACKING THE 5H FEATURE OVER OR JUST SOUTH OF THE ILM
AREA...RESULTING IN AN INCREASE IN ISENTROPIC LIFT LATER THU AND THU
NIGHT. PLENTY OF DEEP MOISTURE IN PLACE WITH FORECAST SOUNDINGS
BECOMING NEARLY SATURATED THROUGH 400MB THU NIGHT. ABUNDANT DEEP
MOISTURE AND STRENGTHENING ISENTROPIC LIFT SHOULD PRODUCE A DECENT
RAINFALL EVENT AS THE PERIOD ENDS. IS WORTH NOTING THAT THE CANADIAN
CONTINUES TO BE A SLOW OUTLIER...BY ABOUT 12 HOURS OR SO. THE
CANADIAN KEEPS THE SHORTWAVE...ALONG WITH THE LARGER SCALE FLOW...A
LITTLE MORE AMPLIFIED THAN THE NAM/GFS/ECMWF SOLUTIONS AND IS SLOWER
TO OPEN UP THE 5H WAVE. AS A RESULT IT HAS PRECIP DEVELOPING LATE
THU NIGHT AND CONTINUING BEYOND THE SCOPE OF THE PERIOD. AT THIS
POINT PLAN TO IGNORE THE SLOWER CANADIAN GIVEN THE RELATIVE
AGREEMENT BETWEEN THE OTHER GUIDANCE AND THE LACK OF ANY SLOWER
SOLUTION WITHIN THE GFS ENSEMBLES.
TEMP FORECAST THU AND THU NIGHT IS DIFFICULT. THERE IS LIKELY TO BE
A VERY NARROW BUT SIGNIFICANT TEMPERATURE GRADIENT ACROSS THE AREA
FOR MUCH OF THU/THU NIGHT. IN FACT MOS NUMBERS VARY BY 10 DEGREE OR
MORE ACROSS THE REGION. FOR NOW FAVORING THE COOLER GFS/ECMWF
SOLUTION OVER THE NAM. RETURN FLOW DEVELOPS EARLIER IN THE NAM WHICH
RESULTS IN FRONT OFF THE COAST LIFTING BACK NORTH AS WARM FRONT.
THIS IS A SHIFT FROM LAST NIGHTS NAM RUN AND AT ODDS WITH
GFS/ECMWF/HPC SOLUTIONS AND IS BEING DISCOUNTED AT THIS POINT. TEMPS
NEAR CLIMO THU WITH INCREASING CLOUD COVER AND THREAT OF RAIN.
ARRIVAL OF COLD AIR WILL DETERMINE HOW LOW TEMPS DROP BEFORE END OF
THU NIGHT...BUT AT THIS POINT LOWS A FEW DEGREES ABOVE CLIMO SEEM IN
ORDER.
&&
.LONG TERM /FRIDAY THROUGH MONDAY/...
AS OF 230 AM TUESDAY...WEAKENING SHORTWAVE AND SURFACE LOW WILL
BE EXITING THE REGION FRI MORNING. LIGHT PRECIP MAY LINGER INTO
LATE MORNING...ESPECIALLY ALONG THE COAST...BUT IT APPEARS
MAJORITY OF THE DAY WILL BE DRY WITH DECREASING CLOUDS IN THE
AFTERNOON. MID LEVEL FLOW IN THE WAKE OF THE SHORTWAVE TROUGH WILL
BE WEST-SOUTHWEST AND WEAKLY DIVERGENT. ALTHOUGH THERE WILL BE A
LACK OF MOISTURE TO THE WEST BOTH GFS AND ECMWF HAVE SOMETHING
BREWING OFF THE SOUTHEAST COAST FOR THE WEEKEND. DIFFERENCES WITH
RESPECT TO HOW FAR OFF THE COAST THE FEATURE DEVELOPS AND HOW
STRONG IT BECOMES. GIVEN LOW CONFIDENCE AND LIMITED AGREEMENT WILL
HOLD ONTO SILENT POP FOR WATERS OVER WEEKEND BUT NOT CARRY ANY POP
FOR LAND AREAS. DRY COLD FRONT CROSSES THE AREA SUN NIGHT WITH
STRONG COLD ADVECTION DEVELOPING BY MON. TEMPS NEAR CLIMO THROUGH
THE WEEKEND FALL BELOW CLIMO MON/MON NIGHT WITH THE ARRIVAL OF
COLDER HIGH PRESSURE FOR THE START OF THE WORK WEEK.
&&
.AVIATION /12Z TUESDAY THROUGH SATURDAY/...
AS OF 12Z...IFR/LIFR VSBYS ARE BEING REPORTED ACROSS THE CWA THIS
MORNING. PATCHES OF DENSE FOG MAY LINGER OVER THE COASTAL TERMINALS
THROUGH MID-MORNING...WITH CONTINUED PERIODS OF IFR/LIFR VSBYS.
LATEST SURFACE ANALYSIS SHOWS A SLOW-MOVING COLD FRONT DRAPED ACROSS
NORTH CAROLINA HAS REACHED OUR NORTHERN COUNTIES...AS KLBT IS NOW
REPORTING NORTH WINDS.
EXPECT PARTLY TO MOSTLY CLOUDY CONDITIONS TODAY...WITH VFR CIGS
DEVELOPING THIS AFTERNOON AT KLBT/KFLO. SOUTHWEST WINDS AOB 10 KNOTS
SHOULD PREVAIL THROUGH THE TAF PERIOD...EXCEPT AT KLBT WHERE THE
WINDS HAVE BECOME NORTHERLY DUE TO FROPA. ANOTHER FOG/STRATUS EVENT
APPEARS LIKELY ACROSS THE REGION AFTER MIDNIGHT WITH ABUNDANT
LOW-LEVEL MOISTURE IN PLACE. FAVORING MORE STRATUS AT THIS POINT AS
THE PRESSURE GRADIENT IS EXPECTED TO TIGHTEN OVERNIGHT...WHICH WILL
INCREASE LOW-LEVEL WINDS AND LIKELY PREVENT VSBYS FROM DROPPING AS
LOW AS TODAY. IFR CONDITIONS ARE CERTAINLY POSSIBLE AFTER 06Z WED...
BUT WENT WITH LOW MVFR FOR THIS TAF CYCLE.
EXTENDED OUTLOOK...MORNING FOG/STRATUS LIKELY AT ALL TERMINALS
WEDNESDAY WITH A SLIGHT CHANCE OF SHOWERS WEDNESDAY AFTERNOON. RAIN
LIKELY THURSDAY INTO EARLY FRIDAY. VFR DEVELOPING SATURDAY.
&&
.MARINE...
NEAR TERM /THROUGH TONIGHT/...
AS OF 630 AM TUESDAY...THE WESTERN ATLANTIC RIDGING WILL CONTINUE
TO DOMINATE THE LOCAL WATERS...PROVIDING S-SW WIND DIRECTIONS.
RELAXED SFC PG WILL TIGHTEN-SOME AS THE STALLED FRONT ACROSS THE
INLAND CAROLINAS SNAKES AND MAKES ITS CLOSEST APPROACH. SPEEDS
GENERALLY 10 KT OR LESS TODAY...INCREASING TO 10-15 KT TONIGHT.
WHERE 60+ SSTS RESIDE...WIND SPEEDS WILL BE A SOLID 15 KT.
SIGNIFICANT SEAS WILL CONTINUE TO BE DOMINATED BY A 2 TO 3 FOOT
EASTERLY SWELL AT 11-13 SECOND PERIODS. WIND DRIVEN WAVES WILL ADD
AT LEAST A FOOT TO THE OVERALL SIGNIFICANT SEAS TONIGHT...WITH 3 TO
4 FT COMMON ACROSS THE LOCAL WATERS. WITH SSTS HAVING INCREASED BY
SEVERAL DEGREES TO BETWEEN 55 AND 60 DEGREES AND NO APPRECIABLE
CHANGE WITH SFC DEWPOINTS OVER THE WATERS...SEA FOG WILL BECOME
MORE PATCHY IN COVERAGE.
SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/...
AS OF 230 AM TUESDAY...SOUTHERLY FLOW INCREASES TO A SOLID 15 KT
LATER WED BEFORE FRONT PUSHES OFF THE COAST WED NIGHT AND OFFSHORE
FLOW DEVELOPS. LIMITED COLD ADVECTION IN THE WAKE OF THE FRONT KEEPS
WINDS UNDER 15 KT INTO MIDDAY THU. LATE THU AND THU NIGHT TIGHTENING
GRADIENT AS WEAK LOW PASSES EAST OF THE WATERS WILL SEE NORTHEAST
FLOW APPROACH THEN EXCEED 20 KT. HEADLINES SEEM LIKELY AS THE PERIOD
ENDS...BUT DIFFICULT TO DETERMINE IF IT WILL BE SCEC OR SCA.
TRAJECTORY OF STRONG WINDS WILL DETERMINE WHETHER OR NOT 6 FT AND
HIGHER SEAS DEVELOP WITHIN 20 NM...MAINLY EAST OF CAPE FEAR AND CAPE
ROMAIN.
LONG TERM /FRIDAY THROUGH SATURDAY/...
AS OF 230 AM TUESDAY...PINCHED GRADIENT LINGERS FRI WITH NORTHEAST
FLOW 20 TO 25 KT CONTINUING INTO THE AFTERNOON. GRADIENT STARTS TO
RELAX AS SURFACE RIDGE AXIS MOVES CLOSER...BUT NORTHEAST FLOW
REMAINS 15 TO 20 KT INTO SAT. GRADIENT WEAKENS FURTHER ON SAT AS
SURFACE HIGH SETTLES SOUTH WITH SPEEDS DROPPING CLOSE TO 10 KT BY
AFTERNOON AS WINDS START TO BACK. STRONG NORTHEAST FLOW WILL CREATE
WIDE RANGE OF SEAS. ON FRI SEAS RUN 1 FT OR LESS OFF WESTERN
BRUNSWICK COAST WHILE WELL EAST OF CAPE FEAR AND CAPE ROMAIN SEAS
WILL APPROACH 10 FT. REDUCTION IN WINDS FRI NIGHT AND SAT WILL LEAD
TO A REDUCTION IN SEAS...2 TO 5 FT.
&&
.ILM WATCHES/WARNINGS/ADVISORIES...
SC...NONE.
NC...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS...III
NEAR TERM...DCH
SHORT TERM...III
LONG TERM...III
AVIATION...BJR
AREA FORECAST DISCUSSION
NWS TULSA OK
541 AM CST TUE JAN 15 2013
.AVIATION...
CONCERNING TAF SITES KTUL/KRVS/KBVO/KMLC/KXNA/KFYV/KFSM.
MID/HIGH LEVEL CLOUDS ARE BEGINNING TO PUSH INTO EASTERN OKLAHOMA
AND NORTHWEST ARKANSAS THIS MORNING. A BROKEN TO OVERCAST MID
CLOUD DECK IS EXPECTED TO REMAIN ACROSS THE REGION THROUGH THE
EVENING HOURS BEFORE CLEARING OFF FROM WEST TO EAST. NORTHERLY
WINDS SHOULD ALSO BEGIN TO SHIFT OUT OF THE WEST AND NORTHWEST
OVERNIGHT TONIGHT. VFR CONDITIONS SHOULD PERSIST AT ALL TAF SITES
THROUGH THE PERIOD.
&&
.PREV DISCUSSION... /ISSUED 343 AM CST TUE JAN 15 2013/
DISCUSSION...
LARGE SCALE TROUGHING THAT HAS REMAINED TO OUR WEST FOR SEVERAL
DAYS IS NOW IN THE PROCESS OF SLOWLY SHIFTING EASTWARD. YET
ANOTHER SMALL SCALE WAVE WILL EJECT AHEAD OF THE UPPER TROUGH
TODAY WITH PRECIP DEVELOPING ACROSS EASTERN TEXAS AND SPREADING
NORTHEASTWARD THROUGH THE AFTERNOON. FAR SE OK WILL BE THE ON THE
NORTHERN PERIPHERY OF THIS PRECIP SHIELD PER VARIOUS MODEL QPF
FIELDS...AND THIS ALIGNS FAIRLY WELL WITH THE ONGOING
STRENGTHENING OF MID LEVEL FRONTOGENETIC BAND IN LATEST RAP DATA.
MEASURABLE PRECIP CHANCES WILL BE LOW ACROSS FAR SE OK WITH ANY
PRECIP THAT DOES FALL EXPECTED TO BE A SLEET / SNOW MIX. ALL
PRECIP WILL HAVE SHIFTED WELL EAST OF THE FORECAST AREA BY THIS
AFTERNOON...WITH TEMPS CONTINUED BELOW NORMAL TODAY AND TONIGHT.
THE BASE OF THE UPPER TROUGH IS LIKELY TO DEVELOP A CLOSED LOW
THAT WILL TRACK ACROSS CENTRAL TEXAS ON WEDNESDAY...WHILE THE
LARGER TROUGH AXIS MAINTAINS A POSITIVE TILT KEEPING ASSOCIATED
PRECIP SHUNTED INTO THE SOUTHEASTERN STATES. WEDNESDAY WILL ALSO
MARK THE MORE NOTICEABLE WARM UP WITH TEMPS RETURNING TO NEAR MID
JANUARY NORMALS.
THE WARMING TREND WILL BE STALLED ON THURSDAY AS A WEAK COLD FRONT
SLIDES THROUGH THE AREA...WITH A MORE ROBUST WARM UP EXPECTED
FRIDAY AND SATURDAY. THE NEXT BIG CHANGE WILL BE SATURDAY NIGHT AS
A STRONGER COLD FRONT SLIDES INTO THE SOUTHERN PLAINS. GENERALLY
SIDED TOWARD THE ECMWF SOLUTION WHICH HAS BEEN CONSISTENT IN
SHOWING THIS FIRST COLD FRONT TO OFFER A MODEST COOL DOWN...AND
QUICKLY FOLLOWED BY A MUCH STRONGER COLD FRONT ON MONDAY. THIS
AIRMASS MARKED BY A 1050+ MB SURFACE PRESSURE WILL PUSH TEMPS WELL
BELOW NORMAL FOR THE FIRST PART OF NEXT WEEK. DRY WEATHER WILL
PREVAIL WITH THE POSSIBLE EXCEPTION OF LIGHT PRECIP ASSOCIATED
WITH THE EARLY WEEK COLD FRONT.
&&
.PRELIMINARY POINT TEMPS/POPS...
TUL 39 20 47 27 / 0 0 0 10
FSM 40 20 46 27 / 10 0 10 10
MLC 40 17 47 27 / 10 0 10 10
BVO 37 13 47 22 / 0 0 0 10
FYV 36 13 42 23 / 10 0 10 10
BYV 36 18 42 27 / 10 0 10 10
MKO 38 16 45 26 / 10 0 10 10
MIO 34 16 45 25 / 0 0 0 10
F10 39 18 46 27 / 0 0 10 10
HHW 39 19 47 28 / 20 10 10 10
&&
.TSA WATCHES/WARNINGS/ADVISORIES...
OK...NONE.
AR...NONE.
&&
$$
AVIATION...20
AREA FORECAST DISCUSSION...UPDATED
NWS FORT WORTH TX
825 AM CST TUE JAN 15 2013
.UPDATE...
LATEST ISENTROPIC PLOTS FROM THE RAP CONTINUE TO SHOW WEAK UPGLIDE
THROUGH 700 MB PERSISTING FOR MOST OF THE MORNING AND EARLY
AFTERNOON. FORECAST SOUNDINGS DEPICT DRYING IN THE UPPER LEVELS OF
THE ATMOSPHERE AND THIS WEAK LIFT WOULD BE SUPPORTIVE OF DRIZZLE.
STARTING TO SEE LIGHT RETURNS WEST OF INTERSTATE 35...BUT NOTHING
HAS BEEN REPORTED YET AT ANY OF THE AREA OBSERVATION SITES. NOT
MUCH PRECIP FELL IN THESE LOCATIONS AND AS THIS WEAK LIFT IN THE
LOWEST ATMOSPHERE SHIFTS EAST...DRIZZLE IS LIKELY TO FORM ACROSS
THE AREA WHICH PICKED UP OVERNIGHT PRECIP. LATEST RAP ALSO KEEPS
TEMPERATURES BELOW FREEZING UNTIL NOON OR 1 PM...AND WE EXTENDED
THE ADVISORY UNTIL NOON. THE FREEZING DRIZZLE WOULD BE PROBLEMATIC
AS THIS WOULD FALL ON TOP OF THE SLEET/SNOW AND MAKE THE AREA
BRIDGES AND OVERPASSES EVEN MORE HAZARDOUS.
HAMPSHIRE
&&
.AVIATION...
KDFW AIRPORT WEATHER WARNING UNTIL 1600UTC /10AM CST/ FOR A WINTRY
MIX AND LIGHT ICE ACCUMULATION.
FOR ALL NORTH TEXAS TAF SITES...A MIX BAG OF WINTRY PRECIPITATION WILL
CONTINUE TO INCREASE IN COVERAGE AND INTENSITY OVER THE NEXT
SEVERAL HOURS. MOVEMENT OF THE ACTIVITY IS NORTHEAST AT 50-55
KNOTS. ICE ACCUMULATION UP TO 1/10 OF AN INCH IS POSSIBLE ON
BEFORE ENDING LATE MORNING.
CIGS AND VIS ARE COMING DOWN TO WITHIN THE PRECIPITATION. DURING
HEAVIER OUTBURST OF SLEET AND SNOW PELLETS...VIS MAY FALL TO
1-2SM AND CIGS DOWN TO AROUND 1000 FT. THIS EVENT WILL WIND DOWN
AFTER 1600 UTC AS TEMPERATURES WARM ABOVE FREEZING AND LIFT BEGINS
TO WANE. WINDS WILL BE NORTHERLY 6-10KTS THROUGH 16/12...THEN
BECOMING WESTERLY. 75
&&
.PREV DISCUSSION... /ISSUED 448 AM CST TUE JAN 15 2013/
SHORT TERM WINTER WEATHER CONCERNS...
ONCE AGAIN WE HAVE A THREAT FOR WINTRY PRECIPITATION TO DEVELOP
OVER PORTIONS OF NORTH AND CENTRAL TX EARLY THIS MORNING. THE LONG
WAVE TROUGH OVER THE WESTERN CONUS HAS BECOME POSITIVELY TILTED
ALREADY THIS MORNING AND ITS AXIS NOW ORIENTED FROM NORTHERN
MINNESOTA SOUTHWEST TO THE SOUTHERN NEW MEXICO AND ARIZONA BORDER.
THE TROUGH WAS SHOWING SIGNS OF MOVING EAST ALREADY EARLY THIS
MORNING. THIS EASTWARD MOVEMENT...COMBINED WITH A COMPACT
SHORTWAVE TROUGH EMBEDDED IN THE SOUTHWEST FLOW ALOFT OVER THE
SOUTHERN HIGH PLAINS IS LIKELY PROVIDING THE LARGE SCALE FORCING
FOR ASCENT EVIDENT ON WATER VAPOR IMAGERY OVER NORTH TX AT THIS
TIME. EVIDENCE OF LARGE SCALE FORCING FOR ASCENT WAS SHOWING UP IN
IR SATELLITE IMAGERY AND VWP PROFILES EARLY THIS MORNING AS WELL.
IR SATELLITE IMAGERY INDICATES COOLING CLOUD TOPS OVER MUCH OF
NORTH AND CENTRAL TX WHILE REGIONAL RADAR VWP SHOWS LOW LEVEL FLOW
VEERING STRONGLY WITH HEIGHT...A SIGN OF WARM AIR ADVECTION AND
ISENTROPIC LIFT. ALL OF THIS IS EVIDENCE THAT WE WILL LIKELY SEE
RADAR RETURNS BLOSSOM AROUND NORTH AND CENTRAL TX THIS MORNING AS
PERSISTENT ASCENT EVENTUALLY RESULTS IN SCATTERED PRECIPITATION
DEVELOP OVER THE REGION.
CONFIDENCE IS FAIRLY HIGH THAT PRECIPITATION WILL DEVELOP OVER
MOST AREAS ALONG AND SOUTHEAST OF A BONHAM TO FORT WORTH TO
LAMPASAS LINE EARLY THIS MORNING. AS A RESULT WENT AHEAD AND
BUMPED UP POPS INTO THE 30 TO 50 PERCENT RANGE FOR THESE LOCATIONS
THROUGH THE MORNING HOURS. CONFIDENCE WAVERS WHEN DETERMINING WHAT
FORM THIS PRECIPITATION WILL FALL AS IT DEVELOPS AND MOVES
NORTHEAST OVER THESE LOCATIONS. THERE ARE SEVERAL FACTORS TO
CONSIDER...AND ILL DETAIL SOME OF THOSE BELOW.
THE EASIEST THING TO NOTICE IS THAT SURFACE TEMPERATURES ARE A
GOOD 5 DEGREES WARMER THAN EXPECTED TO START OFF THE FORECAST
TODAY. THIS IS ONE GOOD CONSEQUENCE OF THE MODELS UNDERESTIMATING
THE STRENGTH OF LARGE SCALE FORCING FOR ASCENT OVER THE
REGION...CLOUDS BUILT IN EARLIER THAN EXPECTED WHICH PREVENTED
TEMPERATURES FROM FALLING BELOW FREEZING SOUTH OF INTERSTATE
20...AT LEAST AS OF 4 AM CST. THIS AT LEAST ALLEVIATES CONCERNS
FOR FREEZING RAIN OVER THE WACO/KILLEEN/TEMPLE AREAS EARLY THIS
MORNING.
FURTHER NORTH...PRECIPITATION IS EXPECTED TO DEVELOP AROUND OR
AFTER 5 AM CST NEAR THE DFW METROPLEX...WHILE 4 AM SURFACE
OBSERVATIONS INDICATED THAT THE WET BULB ZERO LINE WAS LOCATED AS
FAR SOUTH AS CLEBURNE AND WAXAHACHIE. 05Z AMDAR AIRCRAFT SOUNDINGS
INDICATED THAT THE THERMAL PROFILE OVER THE METROPLEX WAS MOSTLY
SUPPORTIVE OF SNOW...WITH A SURFACE TO 700 MB ISOTHERMAL LAYER
HUGGING THE 0 DEG C LINE. THIS OBSERVATION WAS TAKEN FROM AIRCRAFT
BEFORE THE STRONGER LARGE SCALE FORCING FOR ASCENT BUILT OVER THE
AREA...WHICH SHOULD ONLY RESULT IN COOLING ALOFT. AS A RESULT WENT
AHEAD AND ISSUED A WINTER WEATHER ADVISORY FOR THE DFW METROPLEX
AND LOCATIONS TO THE EAST AND NORTHEAST AS THESE LOCATIONS ARE THE
MOST LIKELY TO SEE LIGHT ACCUMULATIONS OF SNOW WITH SOME SLEET
MIXED IN THIS MORNING.
IN TERMS OF AMOUNTS...SNOW OR SLEET AMOUNTS ARE EXPECTED TO VARY
WITHIN THE ADVISORY FROM TRACE AMOUNTS UP TO ONE HALF INCH. THE
VARIATION IS BECAUSE MOST PRECIPITATION IS EXPECTED TO DEVELOP IN
A BANDED FORM WHICH MEANS LOCATIONS WITHIN SNOW BANDS WILL LIKELY
SEE WINTRY PRECIPITATION ACCUMULATE...WHILE THOSE AREAS NOT
INCLUDED IN BANDS MAY SEE LIGHT PRECIPITATION...OR NOTHING AT ALL.
BANDED PRECIPITATION IS FAVORED BECAUSE THE GFS AND NAM BOTH
INDICATE THAT PRECIPITATION IN THE WINTER WEATHER ADVISORY AREA
WILL BE ENHANCED BY FRONTOGENETIC FORCING...MAXIMIZED IN THE H800
TO H700 LAYER. ABOVE 700 MB...BOTH MODELS ALSO INDICATE A
RELATIVELY DEEP LAYER OF NEGATIVE SATURATED EPV (EQUIVALENT
GEOSTROPHIC POTENTIAL VORTICITY) WHICH INDICATES THAT VERTICAL
MOTIONS INITIATED AT THE BOTTOM OF THIS LAYER WILL RESULT IN A
RELEASE OF EITHER CONVECTIVE OR SLANTWISE INSTABILITY. THERE IS A
SHALLOW LAYER OF THETA-E TEMPERATURE DECREASE WITH HEIGHT WITHIN
THIS LAYER...SO A MIX OF CELLULAR AND BANDED PRECIPITATION IS
LIKELY TO OCCUR. EITHER WAY...THIS TYPE OF FORCING AND INSTABILITY
COMBINATION OFTEN FAVORS LARGE GRADIENTS OF WINTRY ACCUMULATION
AND THAT IS WHAT IS EXPECTED ACROSS NORTH TX THIS MORNING.
IN TERMS OF IMPACTS...WENT AHEAD WITH THE WINTER WEATHER ADVISORY
WITHOUT 100 PERCENT CONFIDENCE THAT LOCATIONS IN THE ADVISORY WILL
ALL SEE ACCUMULATING WINTRY PRECIPITATION. THESE ARE SIMPLY THE
AREAS THAT HAVE THE BEST DIAGNOSED COMBINATION OF FORCING AND
MESOSCALE ENHANCEMENTS THIS MORNING. THE ADVISORY WAS ISSUED
BEFORE RADAR RETURNS HAD DEVELOPED OVER THE ADVISORY AREA TO GIVE
EVERYONE WAKING UP EARLY THIS MORNING A HEADS UP ON THE THREAT OF
WINTRY WEATHER IMPACTING THE MORNING COMMUTE. ASSUMING BANDED
WINTRY PRECIPITATION DEVELOPS OVER THE METROPLEX AROUND 5 AM AS
EXPECTED...THIS IS EXPECTED TO HAVE A VERY NEGATIVE IMPACT ON THE
MORNING RUSH HOUR...POSSIBLY CAUSING SIGNIFICANT DELAYS FOR THE
MORNING COMMUTE. BECAUSE TEMPERATURES ARE HOVERING RIGHT AROUND
FREEZING...MOST ROAD SURFACES IN CONTACT WITH THE GROUND SHOULD
SEE MOST SNOW AND SLEET MELT UPON LANDING AS GROUND TEMPERATURES
REMAIN WELL ABOVE FREEZING. BRIDGES AND OVERPASSES HOWEVER ARE
LIKELY TO RETAIN WINTRY ACCUMULATIONS THIS MORNING...RESULTING IN
ICY CONDITIONS ON ELEVATED ROADWAYS...ESPECIALLY AS TRAFFIC DRIVES
OVER IT...COMPACTING ANY ACCUMULATIONS INTO ICE. WINTRY
PRECIPITATION IS EXPECTED TO MOVE NORTHEAST OR DISSIPATE FOR THE
MOST PART AFTER 9 AM CST. LEFT THE ADVISORY GOING THROUGH 10 AM AS
IT MAY TAKE AN HOUR OR SO AFTER WINTRY PRECIPITATION CEASES BEFORE
ROAD CONDITIONS IMPROVE.
REMAINDER OF THE FORECAST...ALL 15/00Z GUIDANCE INDICATES THAT THE
LARGE UPPER TROUGH TO OUR WEST WILL REMAIN POSITIVELY TILTED AS IT
MOVES OVER THE SOUTH PLAINS OVERNIGHT INTO WEDNESDAY MORNING. THIS
WILL RESULT IN SOME LIGHT RAINFALL WEDNESDAY MORNING SOUTHEAST OF A
CANTON TO WACO LINE ASSUMING THE MODELS ARE RESOLVING THIS TROUGHS
EVOLUTION WELL. WITH NO GUIDANCE OFFERING UP THE CLOSED LOW
SOLUTION ANYMORE...DO NOT HAVE ANYTHING IN THE FORECAST TO HANDLE
THIS NOW UNLIKELY ALTERNATIVE SCENARIO. IT SEEMS THAT AFTER THIS
MORNINGS COMPACT SHORTWAVE TROUGH MOVES NORTHEAST...THE LOWER
TROPOSPHERE WILL BECOME DOMINATED ONCE AGAIN BY COLD AIR ADVECTION
WHICH WOULD SERVE TO KEEP THE TROUGH POSITIVELY TILTED AS IT MOVED
OVER THE CWA. ONE IMPORTANT CAVEAT HERE...WILL HAVE TO SEE HOW
LONG AND INTENSE PRECIPITATION ACTUALLY IS ACROSS NORTH...CENTRAL
AND EAST TX TODAY. IF PRECIPITATION HANGS AROUND LONGER THAN
EXPECTED OR IS JUST MORE INTENSE THAN EXPECTED...PRECIPITATION
WILL RELEASE MORE LATENT HEAT INTO THE MIDDLE TROPOSPHERE THAN THE
MODELS WERE PLANNING ON. WITH NO GUIDANCE FAVORING THE CUT-OFF LOW
SOLUTION ANYMORE...ITS HARD TO IMAGINE WE GET ENOUGH LATENT HEAT
RELEASE TO RAISE THICKNESSES ENOUGH DOWNSTREAM TO HAVE AN IMPACT
ON THE TILT OF THIS TROUGH. HOWEVER IT IS THE ONE THING TO WATCH
FOR DURING THE DAY TODAY...IF DEVELOPING PRECIPITATION RESULTS IN
RIDGING OVER EAST TX...THE UPPER CLOUD COULD MAKE AN ATTEMPT AT
BECOMING NEUTRALLY TILTED OR CUTTING OFF AS IT MOVES TOWARDS THE
CWA OVER THE NEXT 24 HRS. WHILE UNLIKELY...WE WILL NEED TO WATCH
FOR THIS JUST IN CASE THE MODELS HAVE MISSED SOMETHING IMPORTANT
HERE.
THURSDAY AND BEYOND...ONCE THIS UPPER TROUGH MOVES EAST OF THE
SOUTH PLAINS...WE WILL MAINTAIN A DRY FORECAST THROUGH EARLY NEXT
WEEK. TEMPERATURES WILL SLOWLY MODERATE BEHIND THE TROUGH...WITH
HIGHS MAKING A RUN AT 60 DEGREES BY SATURDAY AFTERNOON. WE ARE
STILL LOOKING AT A STRONG COLD FRONT TO KICK OFF THE UPCOMING WORK
WEEK. THE ECMWF IS BACK TO INDICATING A FAIRLY ROBUST PUNCH OF DRY
ARCTIC AIR WHILE THE GFS CONTINUES TO ADVERTISE A COOL BUT
MODIFIED AIRMASS SINKING SOUTH THROUGH THE PLAINS. WENT AHEAD WITH
THE COLDER END OF THE SPECTRUM OF AVAILABLE GUIDANCE BUT MAY HAVE
TO GO EVEN LOWER WITH TEMPS IF THE ECMWF VERIFIES.
CAVANAUGH
&&
.PRELIMINARY POINT TEMPS/POPS...
DALLAS-FT. WORTH, TX 36 27 50 33 53 / 60 10 10 10 0
WACO, TX 35 27 51 30 55 / 50 10 20 10 0
PARIS, TX 36 25 46 29 51 / 60 10 10 10 0
DENTON, TX 37 26 49 29 51 / 60 10 10 10 0
MCKINNEY, TX 36 26 47 29 51 / 60 10 10 10 0
DALLAS, TX 35 28 51 34 53 / 60 10 10 10 0
TERRELL, TX 34 26 48 30 53 / 60 10 10 10 0
CORSICANA, TX 34 28 49 31 54 / 50 10 20 10 0
TEMPLE, TX 35 28 50 30 54 / 40 10 20 10 0
MINERAL WELLS, TX 38 24 52 28 55 / 30 10 10 10 0
&&
.FWD WATCHES/WARNINGS/ADVISORIES...
WINTER WEATHER ADVISORY UNTIL NOON CST TODAY FOR TXZ092>095-
102>107-117>123-130>135-144>146-148.
&&
$$
85/85
AREA FORECAST DISCUSSION
NWS DENVER/BOULDER CO
1007 AM MST TUE JAN 15 2013
.UPDATE...
&&
.SHORT TERM...OVERALL...CURRENT FORECAST LOOK ON TRACK. ELONGATED
UPPER TROUGH CURRENTLY ACROSS FAR EASTERN COLORADO WITH NORTHERLY
FLOW ALOFT OVER COLORADO. MOISTURE HAS BEEN STREAMING INTO THE
STATE FROM THE NORTH AND NORTHWEST...THOUGH NOT MUCH IN THE WAY OF
ANY SNOWFALL SHOWING UP ON THE MOUNTAIN WEB CAMS. ENOUGH
OROGRAPHICS TO KEEP THE CURRENT CHANCE POPS FOR MOUNTAINS. HOWEVER
THE WARM AIR ADVECTION AND LACK OF MID LEVEL QG SUPPORT SHOULD KEEP
SNOW AMOUNTS LIMITED. WILL MAINTAIN THE 1-2 INCH RANGE...THOUGH
THE LOCAL 4 INCH SPOTS MAY BE OVERDONE. STILL A SLIGHT CHANCE FOR
SOME LIGHT SNOW THIS EVENING AWAY FROM THE LOCAL DOWNSLOPE OF THE
FOOTHILLS IN FAR NORTHEAST CORNER AND ALONG THE PALMER. ACCUMULATIONS
THERE TO BE MINIMAL. PERHAPS SOME VIRGA ELSEWHERE ACROSS THE
PLAINS. EXPECTED WARMUP TO BE SLOW TO OCCUR TODAY DUE TO
PERSISTANT INVERSIONS IN MOUNTAIN VALLEYS AND LOW LYING AREAS OF
THE PLAINS AS WELL AS THE INCREASING MID LEVEL CLOUD DECK. CURRENT
TEMPERATURE GRIDS SEEM REASONABLE AT THIS TIME...MAY NEED TO
ADJUST A BIT BASED ON CURRENT TRENDS.
.AVIATION...LATEST RAP INDICATING WINDS BECOMING NORTHWEST AROUND
21Z...MORE IN LINE WITH GFS. NAM STILL SHOWING SOUTHWEST TO WEST
WINDS THOUGH LIGHTER THAN EARLIER RUNS. WILL INCLUDE SOME SORT OF
A NORTHWEST WIND FOR THE AREA AIRPORTS AROUND 21Z...WITH SPEEDS
AROUND 10 KTS. WINDS SHOULD SWITCH BACK TO SOUTHERLY THIS EVENING. REST
OF THE TAF TRENDS LOOK IN ORDER. STILL POTENTIAL FOR CEILINGS
AROUND 5000 FEET AGL BETWEEN 01Z AND 09Z WITH ILS CONDITIONS
DEVELOPING...BUT ANY SNOW THAT DEVELOPS SHOULD REMAIN SOUTH AND
EAST OF THE DENVER AREA.
&&
.PREV DISCUSSION... /ISSUED 258 AM MST TUE JAN 15 2013/
SHORT TERM...AFTER A VERY COLD START...THE LONG ANTICIPATED
WARMUP WILL FINALLY BEGIN TODAY. STRONG WARM ADVECTION ALOFT
OCCURS LATER THIS MORNING THROUGH TONIGHT. HOWEVER...THE WARMUP
WILL BE TEMPERED CONSIDERABLY BY THE VERY COLD START AND MID LEVEL
WARM ADVECTION CLOUD DECK WHICH WILL OVERSPREAD THE FORECAST AREA
THIS MORNING. VALLEY LOCATIONS WILL STRUGGLE THE MOST TO WARM
UP...BUT LOCATIONS IN/NEAR THE FOOTHILLS WITH SOME DOWNSLOPE
COMPONENT WILL LIKELY SEE UPPER 20S AND 30S TODAY. THERE IS ENOUGH
MOISTURE AND OROGRAPHICS TO PRODUCE SNOW IN THE MOUNTAINS ALTHOUGH
IT WILL BE LIGHT WITH THE STABILIZING EFFECTS OF WARM ADVECTION.
ACCUMULATIONS SHOULD MAINLY RANGE FROM 1-2 INCHES OVER THE
MOUNTAINS WITH PERHAPS AS MUCH AS 4 INCHES IN A COUPLE SPOTS FROM
ROCKY MOUNTAIN NATIONAL PARK TOWARD THE WYOMING BORDER WHERE
MOISTURE IS MORE PLENTIFUL. HIGHEST CHANCE OF SNOW WILL BE FROM
LATE AFTERNOON THROUGH THIS EVENING. ON THE PLAINS...THE WARM
ADVECTION APPEARS TO BE STRONG ENOUGH TO PRODUCE A CONSIDERABLE
MID LEVEL CLOUD DECK AND MAINLY VIRGA. HOWEVER...THE DOWNSLOPE
COMPONENT WILL BE WEAKEST OVER THE NORTHEAST PLAINS AND PALMER
DIVIDE WITH DEEPER NORTH/NORTHWEST FLOW...SO WILL HAVE A CHANCE OF
LIGHT SNOW THERE TONIGHT. OVERNIGHT LOWS WILL BE CONSIDERABLY
WARMER WITH CONTINUED WARM ADVECTION AND CLOUDS THROUGH MOST OF
THE NIGHT.
INCREASING NORTHWEST WINDS WILL OCCUR AS FLOW ALOFT STRENGTHENS
TODAY. THIS WILL CREATE A PERIOD OF NEAR WIND CHILL WARNING
CRITERIA IN THE MOUNTAINS AND FOOTHILLS THIS MORNING.
HOWEVER...TEMPS ARE BEGINNING TO WARM AS WINDS INCREASE SO WILL
HIGHLIGHT THIS IN THE SHORT TERM FORECAST FOR NOW. ON THE
PLAINS...TEMPERATURES WILL WARM SUFFICIENTLY AS WINDS INCREASE
LATER TODAY THROUGH TONIGHT SO NO HIGHLIGHTS NEEDED.
LONG TERM...STRONG UPPER LEVEL RIDGE WILL BE ALONG THE WEST COAST
AND A DEEP UPPER LEVEL LOW WILL BE CENTERED OVER THE HUDSON BAY TO
START THE EXTENDED PERIOD ON WEDNESDAY. THIS GENERAL PATTERN WILL
HOLD THROUGH THE WEEKEND AND INTO NEXT WEEK. FOR WEDNESDAY THROUGH
FRIDAY...A NORTHWEST FLOW ALOFT WILL BRING MILD AND DRY CONDITIONS
WITH TEMPERATURES CLIMBING ABOVE NORMAL ACROSS NORTHEAST COLORADO.
COULD SEE SOME CLOUDS EARLY WEDNESDAY...OTHERWISE EXPECT MOSTLY
CLEAR SKIES THROUGH FRIDAY. BECAUSE OF THE CLEAR SKIES AND LIGHT
WINDS THE MOUNTAINS VALLEYS WILL BE COLD WITH LOWS WELL BELOW ZERO
AND HIGHS IN THE SINGLE DIGITS AND TEENS.
FOR THIS WEEKEND AND EARLY NEXT WEEK...A SERIES OF WAVES EMBEDDED IN
THE NORTHWEST FLOW ALOFT WILL MOVE ACROSS THE NORTHERN PLAINS. THE
AIR BEHIND THESE SYSTEMS WILL BE COLD. APPEARS THE FORECAST AREA MAY
SEE A GLANCING BLOW OR TWO OF COLD BETWEEN SATURDAY AND TUESDAY.
MODELS DIFFER ON THE TIMING OF THE COLD AIR...SO WILL TREND
TEMPERATURES A LITTLE COOLER BUT KEEP THEM NEAR NORMAL. AS FAR AS
PRECIPITATION GOES...NOT MUCH HOPE FOR ANYTHING THROUGH AT LEAST
TUESDAY.
AVIATION...MID LEVEL CLOUD DECK WITH CEILINGS OF 6000-8000 FEET
WILL SPREAD ACROSS THE FRONT RANGE AIRPORTS 15Z-18Z. CLOUDS WILL
LIKELY LOWER A LITTLE FURTHER 18Z-22Z WITH ILS LANDING CONDITIONS
DEVELOPING AS CEILINGS OF 5000-6000 FEET BECOME MORE WIDESPREAD.
AT THIS TIME...EXPECT NOTHING MORE THAN VIRGA WITH ANY CHANCE OF
SNOW REACHING GROUND SOUTH AND EAST OF KDEN/KAPA.
SOUTHWEST WINDS SHOULD PREVAIL AT 10 KTS OR LESS TODAY AT KDEN
AND KAPA...AND THEN POSSIBLY INCREASE TO 12-15KTS OVERNIGHT. KBJC
SHOULD SEE A MORE WESTERLY COMPONENT DEVELOP BY 18Z-22Z WITH A FEW
GUSTS AROUND 20 KTS POSSIBLE.
&&
.BOU WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...D-L
LONG TERM....MEIER
AVIATION...D-L
AREA FORECAST DISCUSSION...CORRECTED
NWS NEW YORK NY
423 PM EST TUE JAN 15 2013
.SYNOPSIS...
LOW PRESSURE WILL RIDE ALONG THE STALLED FRONT TONIGHT INTO
WEDNESDAY...BRINGING WINTRY WEATHER TO INTERIOR SECTIONS AS IT
MOVES SOUTHEAST OF LONG ISLAND. THE LOW WILL TRACK INTO THE GULF
OF MAINE WEDNESDAY NIGHT. A COLD FRONT WILL CROSS THE REGION LATE
IN THE DAY ON THURSDAY FOLLOWED BY HIGH PRESSURE FRIDAY AND
SATURDAY. A STRONGER COLD FRONT WILL PASS THROUGH ON SUNDAY
FOLLOWED BY HIGH PRESSURE ON MONDAY. ANOTHER FRONTAL SYSTEM MAY
IMPACT THE AREA MONDAY NIGHT INTO TUESDAY.
&&
.NEAR TERM /UNTIL 6 AM WEDNESDAY MORNING/...
CLOUDY SKIES WILL REMAIN AS HIGH PRESSURE MOVES OFF THE NORTHERN
NEW ENGLAND COAST AND WARM AIR ADVECTION ALOFT BEGINS AHEAD OF A
WAVE OF LOW PRESSURE. THIS WAVE WILL BE DEVELOPING OFF THE MID-
ATLANTIC COASTS BY WEDNESDAY MORNING ALONG THAT STALLED FRONT TO
THE SOUTH...EVOLVING AS IT ENCOUNTERS AN INCREASING BAROCLINIC
ENVIRONMENT. WITH INCREASING ISOENTROPIC LIFT...ONSET OF PRECIP
LIKELY 3-6Z FROM SOUTH TO NORTH AFTER NOTING REFLECTIVITY
FORECASTS BY HRRR AND PRECIP FIELDS OF NAM...GFS...ECMWF...AND
CMC. THE INTENSITY OF THE PRECIPITATION INCREASES TOWARDS DAYBREAK
AS THE REGION GETS CLOSER TO THE RIGHT ENTRANCE REGION OF A
160-180 KT JET AROUND 250MB. MID LEVEL FRONTOGENESIS FOCUSED
MOSTLY TO THE NORTH OF THE FORECAST REGION WITH ABRUPT CUTOFFS TO
THE GFS AND NAM SNOWFALL BUT LOWERED TEMPERATURES AND LAYERS
ENOUGH TO ACCOUNT FOR WET BULB COOLING ESPECIALLY AT THE ONSET.
CONCERNING PRECIP TYPE...A COMPLEX FORECAST. GENERALLY THOUGH
EXPECTING SNOW ACROSS THE INTERIOR AREAS...MIXING WITH SLEET TO
THE SOUTHEAST WITH RAIN AND SLEET AT THE COAST. OVERNIGHT...SOME
WARMING IN THE TEMPERATURES ALOFT...GENERALLY BETWEEN 900 AND 700
HPA...WILL PRESENT A LARGE ENOUGH LAYER TO REDUCE THE HYDROMETEORS
TO SLEET ESPECIALLY WITH ANY HIGHER INTENSITY PRECIPITATION. SOME
FREEZING RAIN WILL BE POSSIBLE AS WELL ACROSS A PORTION OF THE
INTERIOR AREAS BUT WILL BE DEPENDENT ON THE AMOUNT OF WET BULB
COOLING AND TEMPERATURES ARE RIGHT NEAR THE FREEZING MARK. SOME
CHANGES ARE POSSIBLE WITH SUBSEQUENT FORECASTS WITH THE
RAIN/SLEET/FREEZING RAIN AND SNOW LINES.
&&
.SHORT TERM /6 AM WEDNESDAY MORNING THROUGH WEDNESDAY NIGHT/...
THE LOW SOUTHEAST OF LONG ISLAND TRAVERSES RIGHT NEAR THE
BENCHMARK OF 40N/-70W AS IT GRADUALLY DEEPENS ON A NORTHEAST
TRACK. THE LOW MOVES TO THE GULF OF MAINE BY WEDNESDAY EVENING
AHEAD OF A DEEPENING UPPER LEVEL TROUGH SINKING INTO THE REGION.
STRONG JET DYNAMICS ALOFT AND THAT RIGHT ENTRANCE REGION WILL MEAN
A LONGER DURATION OF PRECIP...ALTHOUGH NOT MUCH ADDITIONAL
ACCUMULATION EXPECTED BY MID AFTERNOON AND EVENING BY WHICH
TIME...IT WILL BE MOSTLY OVER THE EASTERN SECTIONS OF SOUTHERN CT
AND LONG ISLAND.
WEATHER DRIES WITH A GRADUAL DECREASE IN CLOUDS WEDNESDAY NIGHT.
STRONGER WINDS AT THE SURFACE WILL BE INVOKED AHEAD OF THE NEXT
COLD FRONT AND AN INCREASING PRESSURE GRADIENT.
&&
.LONG TERM /THURSDAY THROUGH TUESDAY/...
A QUIET AND GRADUALLY TURNING COLDER PERIOD AS A SERIES OF COLD
FRONTS PASS THROUGH. FLURRIES OR LIGHT SNOW SHOWERS LOOK TO BE
THE ONLY PCPN UNTIL PERHAPS MON NIGHT INTO TUE. POTENTIALLY THE
COLDEST WEATHER OF THE WINTER ON TAP BY THE MIDDLE OF NEXT WEEK.
LONG WAVE TROUGH ACROSS THE EASTERN 2/3 OF THE CONUS GRADUALLY
DEEPENS INTO THE MIDDLE OF NEXT WEEK AS SHORTWAVE ENERGY ROTATES
INTO THE LONG WAVE AROUND A STRONG POLAR VORTEX OVER HUDSON BAY.
LONG WAVE TROUGH ACROSS THE EASTERN 2/3 OF THE CONUS GRADUALLY
DEEPENS OVER THE WEEKEND AND INTO EARLY NEXT WEEK AS THE UPPER
PATTERN AMPLIFIES. STRONG POLAR VORTEX OVER HUDSON BAY THU MORNING
WILL GRADUALLY WEAKEN AS IT TRACKS EASTWARD...KEEPING THE COLDEST
AIR ASSOCIATED WITH IT TO OUR NORTH. A SHORTWAVE TROUGH CURRENTLY
OVER ALASKA WILL DIVE THROUGH THE NW FLOW THROUGH WESTERN CANADA
AND THE NORTHERN PLAINS FRI AND SAT AIDING IN THE AMPLIFICATION OF
THE TROUGH OVER THE EASTERN US AND RIDGE OUT WEST. THIS ENERGY
ROUNDS THE BASE OF THE TROUGH IN THE GREAT LAKES AND MOVES THROUGH
THE OHIO VALLEY AND NEW ENGLAND SAT NIGHT AND SUN.
AT THE SFC...A COLD FRONT WILL TRACK ACROSS THE REGION THU EVE.
MODELS CONTINUE TO KEEP THE AREA DRY WITH ITS PASSAGE AND KEPT
CONSISTENCY WITH THE PREVIOUS FORECASTS THAT SUPPORT THIS IDEA.
H5 FLOW FLATTENS ON FRI WITH CLIPPER LOW PASSING WELL TO OUR
NORTH. HIGH PRES PASSES S OF THE LOCAL AREA FRI INTO SAT WITH FAIR
AND DRY WEATHER. IMPULSE DIVING OUT OF CENTRAL CANADA WILL RESULT
IN A CHANGE IN THE RECENT PATTERN. LOW PRES IS FORECAST TO TRACK
FROM THE GREAT LAKES THROUGH NORTHERN NEW ENGLAND DRAGGING A
STRONG COLD FRONT ACROSS THE AREA ON SUNDAY.
MEDIUM RANGE GUIDANCE BEGINS TO DIVERGE EARLY NEXT WEEK. THE ECMWF
INDICATES A FAIRLY POTENT SHORTWAVE DIVING FROM CENTRAL CANADA
INTO THE UPPER MISSISSIPPI VALLEY...WHILE THE GFS IS WEAKER. REST
OF THE GUIDANCE IS SPLIT WITH THE UKMET SIMILAR TO THE GFS AND THE
CMC SIMILAR TO THE EC. SINCE THE EC PERFORMS BETTER IN THE MEDIUM
RANGE...FOLLOWED HPC GUIDANCE CLOSELY BEYOND SUNDAY SINCE IT ALSO
INCORPORATES THE EC ENS MEAN.
TEMPS DROP TO SEASONABLE ON FRIDAY BEHIND THE COLD FRONT...THEN
REBOUND TO ABOVE NORMAL IN THE WAA ON SATURDAY. TEMPS FOR SUNDAY
ARE TRICKY DEPENDING ON TIMING OF THE COLD FROPA. BUT WILL
CERTAINLY FALL TO SLIGHTLY BELOW NORMAL ON MONDAY AND TUE.
&&
.AVIATION /21Z TUESDAY THROUGH SUNDAY/...
HIGH PRESSURE OVER THE AREA MOVES NORTHEAST THIS AFTERNOON INTO THIS
EVENING. A WAVE OF LOW PRESSURE APPROACHES FROM THE SOUTHWEST LATE
THIS AFTERNOON AND AFFECTS THE TERMINALS LATE THIS EVENING THROUGH
THE END OF THE FORECAST PERIOD.
VFR CONDITIONS UNTIL THE ONSET OF PRECIPITATION AFTER 03Z.
CONDITIONS LOWER TO MVFR AND THEN IFR IN A MIXTURE OF PRECIPITATION
WITH RAIN AND SLEET AT THE NYC METRO TERMINALS AND A MIX OF RAIN
SNOW AND SLEET FROM KTEB TO KHPN TO KGON...ALL SNOW IS EXPECTED AT
KSWF TIL WEDNESDAY MORNING. A PERIOD OF FREEZING RAIN WILL BE
POSSIBLE AT KSWF AFTER 13Z BEFORE CHANGING TO ALL RAIN. THERE COULD
BE A PERIOD OF FREEZING RAIN AS FAR SOUTH AS COASTAL CONNECTICUT
HOWEVER CONFIDENCE IS LOW AT THIS TIME.
NY METRO ENHANCED AVIATION WEATHER SUPPORT...
DETAILED INFORMATION...INCLUDING HOURLY TAF WIND COMPONENT FCSTS CAN
BE FOUND AT: HTTP:/WWW.ERH.NOAA.GOV/ZNY/N90 (LOWER CASE)
KEWR FCSTER COMMENTS: NO UNSCHEDULED AMENDMENTS EXPECTED THROUGH
02Z. A MIX OF RAIN AND SLEET DEVELOPS AROUND 03Z A TENTH OF AN INCH
OF SLEET IS POSSIBLE. CONDITIONS BECOMING MVFR.
THE AFTERNOON KEWR HAZE POTENTIAL FORECAST IS GREEN...WHICH IMPLIES
SLANT RANGE VISIBILITY 7SM OR GREATER OUTSIDE OF CLOUD.
KJFK FCSTER COMMENTS: NO UNSCHEDULED AMENDMENTS EXPECTED THROUGH
02Z. A MIX OF RAIN AND SLEET DEVELOPS AROUND 03Z A TENTH OF AN INCH
OF SLEET IS POSSIBLE. CONDITIONS BECOMING MVFR.
KLGA FCSTER COMMENTS: NO UNSCHEDULED AMENDMENTS EXPECTED THROUGH
02Z. A MIX OF RAIN AND SLEET DEVELOPS AROUND 03Z A TENTH OF AN INCH
OF SLEET IS POSSIBLE. CONDITIONS BECOMING MVFR.
KTEB FCSTER COMMENTS: NO UNSCHEDULED AMENDMENTS EXPECTED THROUGH
02Z. A MIX OF SNOW AND SLEET DEVELOPS AROUND 03Z. UP TO AN INCH OF
SNOW AND SLEET IS POSSIBLE.
KHPN FCSTER COMMENTS: NO UNSCHEDULED AMENDMENTS EXPECTED THROUGH
02Z. A PERIOD OF SNOW DEVELOPS AROUND 03Z MIXING WITH SLEET AND RAIN
AFTER MIDNIGHT. UP TO 2 INCHES IF SNOW AND SLEET IS POSSIBLE.
KISP FCSTER COMMENTS: NO UNSCHEDULED AMENDMENTS EXPECTED. RAIN
DEVELOPS AFTER 03Z WITH MARGINAL CONDITIONS DEVELOPING.
.OUTLOOK FOR 18Z WEDNESDAY THROUGH SUNDAY...
.WEDNESDAY AFTERNOON...IFR...RAIN ENDING LATE IN THE DAY WITH
IMPROVEMENT TO MARGINAL VFR. WINDS BECOMING WESTERLY.
.WEDNESDAY EVENING...BECOMING VFR EARLY.
.THURSDAY...VFR...W-NW GUSTY WINDS 10-15 G 25KTS.
.FRIDAY-SATURDAY...VFR.
.SUNDAY...MAINLY VFR. POSSIBLY MVFR WITH LIGHT PRECIPITATION WITH
COLD FRONTAL PASSAGE.
&&
.MARINE...
SUB SCA CONDITIONS EXPECTED THROUGH WEDNESDAY WITH INCREASING
NORTHEAST FLOW. NEXT CHANCE OF SCA CONDITIONS COMES WEDNESDAY
NIGHT WITH INCREASING PRESSURE GRADIENT AND WESTERLY FLOW.
SCA CONDS ARE POSSIBLE WED NIGHT AND THU IN RESPONSE TO THE
COMBINATION OF A TIGHT PRESSURE GRADIENT AND COLD AIR ADVECTION
BEHIND THE DEPARTING LOW. A WEAKENING COLD FRONT/TROUGH MOVES ACROSS
THE WATERS THU NIGHT WITH MARGINAL SCA CONDS POSSIBLE...MAINLY ON
THE OCEAN WATERS. SUB-ADVSY CONDS RETURN ON FRI WITH A WEAKENING
PRES GRADIENT AS HIGH PRES BUILDS INTO THE REGION. THE GRADIENT WILL
TIGHTEN ONCE AGAIN FRI NIGHT AND SAT AS HIGH PRES BUILDS TO THE S OF
THE AREA AND LOW PRES TRACKS WELL TO THE NORTH. SCA CONDS ARE
EXPECTED ONCE AGAIN. AFTER A BRIEF LULL SAT NIGHT INTO SUN...STRONG
SCA CONDS WILL RETURN YET AGAIN AS A STRONG COLD FRONT SWEEPS ACROSS
THE AREA.
&&
.HYDROLOGY...
QPF OF AROUND 0.4 TO 0.6 INCH LIQUID EQUIVALENT EXPECTED TONIGHT
INTO WED WITH HIGHER AMOUNTS NEAR THE COAST. MOST OF THIS SHOULD
FALL AS SNOW AWAY FROM THE IMMEDIATE CT COAST AND NYC METRO AREAS.
NO SIGNIFICANT PRECIPITATION IS EXPECTED THROUGH THE REMAINDER OF
THE WEEK.
&&
.OKX WATCHES/WARNINGS/ADVISORIES...
CT...WINTER WEATHER ADVISORY FROM MIDNIGHT TONIGHT TO 4 PM EST
WEDNESDAY FOR CTZ005>010.
NY...WINTER WEATHER ADVISORY FROM MIDNIGHT TONIGHT TO 4 PM EST
WEDNESDAY FOR NYZ067>071.
NJ...WINTER WEATHER ADVISORY FROM MIDNIGHT TONIGHT TO 4 PM EST
WEDNESDAY FOR NJZ002-004-103>105-107.
MARINE...NONE.
&&
$$
SYNOPSIS...24/JM
NEAR TERM...JM
SHORT TERM...JM
LONG TERM...24
AVIATION...MET
MARINE...24/JM
HYDROLOGY...24/JM
AREA FORECAST DISCUSSION
NWS NEW YORK NY
417 PM EST TUE JAN 15 2013
.SYNOPSIS...
LOW PRESSURE WILL RIDE ALONG THE STALLED FRONT TONIGHT INTO
WEDNESDAY...BRINGING WINTRY WEATHER TO INTERIOR SECTIONS AS IT
MOVES SOUTHEAST OF LONG ISLAND AND INTO GULF OF MAINE WEDNESDAY
NIGHT. A COLD FRONT WILL CROSS THE REGION LATE IN THE DAY ON
THURSDAY FOLLOWED BY HIGH PRESSURE FRIDAY AND SATURDAY. A STRONGER
COLD FRONT WILL PASS THROUGH ON SUNDAY FOLLOWED BY HIGH PRESSURE
ON MONDAY. ANOTHER FRONTAL SYSTEM MAY IMPACT THE AREA MONDAY NIGHT
INTO TUESDAY.
&&
.NEAR TERM /UNTIL 6 AM WEDNESDAY MORNING/...
CLOUDY SKIES WILL REMAIN AS HIGH PRESSURE MOVES OFF THE NORTHERN
NEW ENGLAND COAST AND WARM AIR ADVECTION ALOFT BEGINS AHEAD OF A
WAVE OF LOW PRESSURE. THIS WAVE WILL BE DEVELOPING OFF THE MID-
ATLANTIC COASTS BY WEDNESDAY MORNING ALONG THAT STALLED FRONT TO
THE SOUTH...EVOLVING AS IT ENCOUNTERS AN INCREASING BAROCLINIC
ENVIRONMENT. WITH INCREASING ISOENTROPIC LIFT...ONSET OF PRECIP
LIKELY 3-6Z FROM SOUTH TO NORTH AFTER NOTING REFLECTIVITY
FORECASTS BY HRRR AND PRECIP FIELDS OF NAM...GFS...ECMWF...AND
CMC. THE INTENSITY OF THE PRECIPITATION INCREASES TOWARDS DAYBREAK
AS THE REGION GETS CLOSER TO THE RIGHT ENTRANCE REGION OF A
160-180 KT JET AROUND 250MB. MID LEVEL FRONTOGENESIS FOCUSED
MOSTLY TO THE NORTH OF THE FORECAST REGION WITH ABRUPT CUTOFFS TO
THE GFS AND NAM SNOWFALL BUT LOWERED TEMPERATURES AND LAYERS
ENOUGH TO ACCOUNT FOR WET BULB COOLING ESPECIALLY AT THE ONSET.
CONCERNING PRECIP TYPE...A COMPLEX FORECAST. GENERALLY THOUGH
EXPECTING A MIX OF SNOW ACROSS THE INTERIOR AREAS...MIXING WITH
SLEET TO THE SOUTHEAST WITH RAIN AND SLEET AT THE COAST.
OVERNIGHT...SOME WARMING IN THE TEMPERATURES ALOFT...GENERALLY
BETWEEN 700 AND 900 HPA...WILL PRESENT A LARGE ENOUGH LAYER TO
REDUCE THE HYDROMETEORS TO SLEET ESPECIALLY WITH ANY HIGHER
INTENSITY PRECIPITATION. SOME FREEZING RAIN WILL BE POSSIBLE AS
WELL ACROSS A PORTION OF THE INTERIOR AREAS BUT WILL BE DEPENDENT
ON THE AMOUNT OF WET BULB COOLING AND TEMPERATURES ARE RIGHT NEAR
THE FREEZING MARK. SOME CHANGES ARE POSSIBLE WITH SUBSEQUENT
FORECASTS WITH THE RAIN/SLEET/FREEZING RAIN AND SNOW LINES.
&&
.SHORT TERM /6 AM WEDNESDAY MORNING THROUGH WEDNESDAY NIGHT/...
THE LOW SOUTHEAST OF LONG ISLAND TRAVERSES RIGHT NEAR THE
BENCHMARK OF 40N/-70W AS IT GRADUALLY DEEPENS ON A NORTHEAST
TRACK. THE LOW MOVES TO THE GULF OF MAINE BY WEDNESDAY EVENING
AHEAD OF A DEEPENING UPPER LEVEL TROUGH SINKING INTO THE REGION.
STRONG JET DYNAMICS ALOFT AND THAT RIGHT ENTRANCE REGION WILL MEAN
A LONGER DURATION OF PRECIP...ALTHOUGH NOT MUCH ADDITIONAL
ACCUMULATION EXPECTED BY MID AFTERNOON AND EVENING BY WHICH
TIME...IT WILL BE MOSTLY OVER THE EASTERN SECTIONS OF SOUTHERN CT
AND LONG ISLAND.
WEATHER DRIES WITH A GRADUAL DECREASE IN CLOUDS WEDNESDAY NIGHT.
STRONGER WINDS AT THE SURFACE WILL BE INVOKED AHEAD OF THE NEXT
COLD FRONT AND AN INCREASING PRESSURE GRADIENT.
&&
.LONG TERM /THURSDAY THROUGH TUESDAY/...
A QUIET AND GRADUALLY TURNING COLDER PERIOD AS A SERIES OF COLD
FRONTS PASS THROUGH. FLURRIES OR LIGHT SNOW SHOWERS LOOK TO BE
THE ONLY PCPN UNTIL PERHAPS MON NIGHT INTO TUE. POTENTIALLY THE
COLDEST WEATHER OF THE WINTER ON TAP BY THE MIDDLE OF NEXT WEEK.
LONG WAVE TROUGH ACROSS THE EASTERN 2/3 OF THE CONUS GRADUALLY
DEEPENS INTO THE MIDDLE OF NEXT WEEK AS SHORTWAVE ENERGY ROTATES
INTO THE LONG WAVE AROUND A STRONG POLAR VORTEX OVER HUDSON BAY.
LONG WAVE TROUGH ACROSS THE EASTERN 2/3 OF THE CONUS GRADUALLY
DEEPENS OVER THE WEEKEND AND INTO EARLY NEXT WEEK AS THE UPPER
PATTERN AMPLIFIES. STRONG POLAR VORTEX OVER HUDSON BAY THU MORNING
WILL GRADUALLY WEAKEN AS IT TRACKS EASTWARD...KEEPING THE COLDEST
AIR ASSOCIATED WITH IT TO OUR NORTH. A SHORTWAVE TROUGH CURRENTLY
OVER ALASKA WILL DIVE THROUGH THE NW FLOW THROUGH WESTERN CANADA
AND THE NORTHERN PLAINS FRI AND SAT AIDING IN THE AMPLIFICATION OF
THE TROUGH OVER THE EASTERN US AND RIDGE OUT WEST. THIS ENERGY
ROUNDS THE BASE OF THE TROUGH IN THE GREAT LAKES AND MOVES THROUGH
THE OHIO VALLEY AND NEW ENGLAND SAT NIGHT AND SUN.
AT THE SFC...A COLD FRONT WILL TRACK ACROSS THE REGION THU EVE.
MODELS CONTINUE TO KEEP THE AREA DRY WITH ITS PASSAGE AND KEPT
CONSISTENCY WITH THE PREVIOUS FORECASTS THAT SUPPORT THIS IDEA.
H5 FLOW FLATTENS ON FRI WITH CLIPPER LOW PASSING WELL TO OUR
NORTH. HIGH PRES PASSES S OF THE LOCAL AREA FRI INTO SAT WITH FAIR
AND DRY WEATHER. IMPULSE DIVING OUT OF CENTRAL CANADA WILL RESULT
IN A CHANGE IN THE RECENT PATTERN. LOW PRES IS FORECAST TO TRACK
FROM THE GREAT LAKES THROUGH NORTHERN NEW ENGLAND DRAGGING A
STRONG COLD FRONT ACROSS THE AREA ON SUNDAY.
MEDIUM RANGE GUIDANCE BEGINS TO DIVERGE EARLY NEXT WEEK. THE ECMWF
INDICATES A FAIRLY POTENT SHORTWAVE DIVING FROM CENTRAL CANADA
INTO THE UPPER MISSISSIPPI VALLEY...WHILE THE GFS IS WEAKER. REST
OF THE GUIDANCE IS SPLIT WITH THE UKMET SIMILAR TO THE GFS AND THE
CMC SIMILAR TO THE EC. SINCE THE EC PERFORMS BETTER IN THE MEDIUM
RANGE...FOLLOWED HPC GUIDANCE CLOSELY BEYOND SUNDAY SINCE IT ALSO
INCORPORATES THE EC ENS MEAN.
TEMPS DROP TO SEASONABLE ON FRIDAY BEHIND THE COLD FRONT...THEN
REBOUND TO ABOVE NORMAL IN THE WAA ON SATURDAY. TEMPS FOR SUNDAY
ARE TRICKY DEPENDING ON TIMING OF THE COLD FROPA. BUT WILL
CERTAINLY FALL TO SLIGHTLY BELOW NORMAL ON MONDAY AND TUE.
&&
.AVIATION /21Z TUESDAY THROUGH SUNDAY/...
HIGH PRESSURE OVER THE AREA MOVES NORTHEAST THIS AFTERNOON INTO THIS
EVENING. A WAVE OF LOW PRESSURE APPROACHES FROM THE SOUTHWEST LATE
THIS AFTERNOON AND AFFECTS THE TERMINALS LATE THIS EVENING THROUGH
THE END OF THE FORECAST PERIOD.
VFR CONDITIONS UNTIL THE ONSET OF PRECIPITATION AFTER 03Z.
CONDITIONS LOWER TO MVFR AND THEN IFR IN A MIXTURE OF PRECIPITATION
WITH RAIN AND SLEET AT THE NYC METRO TERMINALS AND A MIX OF RAIN
SNOW AND SLEET FROM KTEB TO KHPN TO KGON...ALL SNOW IS EXPECTED AT
KSWF TIL WEDNESDAY MORNING. A PERIOD OF FREEZING RAIN WILL BE
POSSIBLE AT KSWF AFTER 13Z BEFORE CHANGING TO ALL RAIN. THERE COULD
BE A PERIOD OF FREEZING RAIN AS FAR SOUTH AS COASTAL CONNECTICUT
HOWEVER CONFIDENCE IS LOW AT THIS TIME.
NY METRO ENHANCED AVIATION WEATHER SUPPORT...
DETAILED INFORMATION...INCLUDING HOURLY TAF WIND COMPONENT FCSTS CAN
BE FOUND AT: HTTP:/WWW.ERH.NOAA.GOV/ZNY/N90 (LOWER CASE)
KEWR FCSTER COMMENTS: NO UNSCHEDULED AMENDMENTS EXPECTED THROUGH
02Z. A MIX OF RAIN AND SLEET DEVELOPS AROUND 03Z A TENTH OF AN INCH
OF SLEET IS POSSIBLE. CONDITIONS BECOMING MVFR.
THE AFTERNOON KEWR HAZE POTENTIAL FORECAST IS GREEN...WHICH IMPLIES
SLANT RANGE VISIBILITY 7SM OR GREATER OUTSIDE OF CLOUD.
KJFK FCSTER COMMENTS: NO UNSCHEDULED AMENDMENTS EXPECTED THROUGH
02Z. A MIX OF RAIN AND SLEET DEVELOPS AROUND 03Z A TENTH OF AN INCH
OF SLEET IS POSSIBLE. CONDITIONS BECOMING MVFR.
KLGA FCSTER COMMENTS: NO UNSCHEDULED AMENDMENTS EXPECTED THROUGH
02Z. A MIX OF RAIN AND SLEET DEVELOPS AROUND 03Z A TENTH OF AN INCH
OF SLEET IS POSSIBLE. CONDITIONS BECOMING MVFR.
KTEB FCSTER COMMENTS: NO UNSCHEDULED AMENDMENTS EXPECTED THROUGH
02Z. A MIX OF SNOW AND SLEET DEVELOPS AROUND 03Z. UP TO AN INCH OF
SNOW AND SLEET IS POSSIBLE.
KHPN FCSTER COMMENTS: NO UNSCHEDULED AMENDMENTS EXPECTED THROUGH
02Z. A PERIOD OF SNOW DEVELOPS AROUND 03Z MIXING WITH SLEET AND RAIN
AFTER MIDNIGHT. UP TO 2 INCHES IF SNOW AND SLEET IS POSSIBLE.
KISP FCSTER COMMENTS: NO UNSCHEDULED AMENDMENTS EXPECTED. RAIN
DEVELOPS AFTER 03Z WITH MARGINAL CONDITIONS DEVELOPING.
.OUTLOOK FOR 18Z WEDNESDAY THROUGH SUNDAY...
.WEDNESDAY AFTERNOON...IFR...RAIN ENDING LATE IN THE DAY WITH
IMPROVEMENT TO MARGINAL VFR. WINDS BECOMING WESTERLY.
.WEDNESDAY EVENING...BECOMING VFR EARLY.
.THURSDAY...VFR...W-NW GUSTY WINDS 10-15 G 25KTS.
.FRIDAY-SATURDAY...VFR.
.SUNDAY...MAINLY VFR. POSSIBLY MVFR WITH LIGHT PRECIPITATION WITH
COLD FRONTAL PASSAGE.
&&
.MARINE...
SUB SCA CONDITIONS EXPECTED THROUGH WEDNESDAY WITH INCREASING
NORTHEAST FLOW. NEXT CHANCE OF SCA CONDITIONS COMES WEDNESDAY
NIGHT WITH INCREASING PRESSURE GRADIENT AND WESTERLY FLOW.
SCA CONDS ARE POSSIBLE WED NIGHT AND THU IN RESPONSE TO THE
COMBINATION OF A TIGHT PRESSURE GRADIENT AND COLD AIR ADVECTION
BEHIND THE DEPARTING LOW. A WEAKENING COLD FRONT/TROUGH MOVES ACROSS
THE WATERS THU NIGHT WITH MARGINAL SCA CONDS POSSIBLE...MAINLY ON
THE OCEAN WATERS. SUB-ADVSY CONDS RETURN ON FRI WITH A WEAKENING
PRES GRADIENT AS HIGH PRES BUILDS INTO THE REGION. THE GRADIENT WILL
TIGHTEN ONCE AGAIN FRI NIGHT AND SAT AS HIGH PRES BUILDS TO THE S OF
THE AREA AND LOW PRES TRACKS WELL TO THE NORTH. SCA CONDS ARE
EXPECTED ONCE AGAIN. AFTER A BRIEF LULL SAT NIGHT INTO SUN...STRONG
SCA CONDS WILL RETURN YET AGAIN AS A STRONG COLD FRONT SWEEPS ACROSS
THE AREA.
&&
.HYDROLOGY...
QPF OF AROUND 0.4 TO 0.6 INCH LIQUID EQUIVALENT EXPECTED TONIGHT
INTO WED WITH HIGHER AMOUNTS NEAR THE COAST. MOST OF THIS SHOULD
FALL AS SNOW AWAY FROM THE IMMEDIATE CT COAST AND NYC METRO AREAS.
NO SIGNIFICANT PRECIPITATION IS EXPECTED THROUGH THE REMAINDER OF
THE WEEK.
&&
.OKX WATCHES/WARNINGS/ADVISORIES...
CT...WINTER WEATHER ADVISORY FROM MIDNIGHT TONIGHT TO 4 PM EST
WEDNESDAY FOR CTZ005>010.
NY...WINTER WEATHER ADVISORY FROM MIDNIGHT TONIGHT TO 4 PM EST
WEDNESDAY FOR NYZ067>071.
NJ...WINTER WEATHER ADVISORY FROM MIDNIGHT TONIGHT TO 4 PM EST
WEDNESDAY FOR NJZ002-004-103>105-107.
MARINE...NONE.
&&
$$
SYNOPSIS...24/JM
NEAR TERM...JM
SHORT TERM...JM
LONG TERM...24
AVIATION...MET
MARINE...24/JM
HYDROLOGY...24/JM
AREA FORECAST DISCUSSION
NWS INDIANAPOLIS IN
513 PM EST TUE JAN 15 2013
.UPDATE...
THE AVIATION SECTION HAS BEEN UPDATED BELOW.
&&
.SYNOPSIS...
ISSUED AT 212 PM EST TUE JAN 15 2013
QUIET WEATHER CAN BE EXPECTED UNDER HIGH PRESSURE THROUGH THE END
OF THE WEEK WITH TEMPERATURES NEAR NORMAL FOR THIS TIME OF YEAR.
COULD SEE A BRIEF WARM UP SATURDAY INTO THE 40S BEFORE
TEMPERATURES DROP BACK TO NORMAL SUNDAY AND THEN GET VERY COLD TO
START OUT THE WEEK. A CLIPPER SYSTEM WILL MOVE THROUGH SUNDAY
NIGHT THROUGH MONDAY NIGHT BRINGING CHANCES FOR SNOW.
&&
.NEAR TERM /TONIGHT/...
ISSUED AT 212 PM EST TUE JAN 15 2013
SKIES SHOULD START OUT MOSTLY CLOUDY WITH A LOW PRESSURE SYSTEM
MOVING NORTHEAST OUT OF THE GULF AND THROUGH THE SOUTHEASTERN U.S. A
BIT OF MODEL DISAGREEMENT OVER HOW FAR NORTH PRECIPITATION
ASSOCIATED WITH THIS SYSTEM WILL GET DESPITE SIMILAR POSITIONS AND
STRENGTH FOR THE LOW PRESSURE CENTER. THE RAP AND GEM WERE THE
FURTHEST NORTH AND BRING THE PRECIP INTO THE FAR SOUTHEASTERN
COUNTIES. THE GFS KEEPS THE PRECIP WELL TO THE SOUTH...WHILE THE NAM
AND 0Z ECMWF JUST CLIP THE FAR SOUTHEAST WITH A HUNDREDTH OF QPF.
WITH THE VARIETY OF SOLUTIONS SHOULD CARRY A LOW CHANCE POP IN THE
FAR SOUTHEAST WITH DRY WEATHER BUT MOSTLY CLOUDY SKIES ELSEWHERE.
WENT WITH LOWS A DEGREE OR TWO BELOW GUIDANCE WITH EXPECTED COLD
ADVECTION.
&&
.SHORT TERM /WEDNESDAY THROUGH FRIDAY/...
ISSUED AT 212 PM EST TUE JAN 15 2013
HIGH PRESSURE WILL REMAIN OVER THE AREA THROUGH THE SHORT TERM. A
LOW PRESSURE SYSTEM MOVING ACROSS THE HUDSON BAY WILL DRAG A COLD
FRONT ACROSS THE GREAT LAKES WEDNESDAY AND WEDNESDAY NIGHT...BUT IT LOOKS
LIKE ALL THE FORCING ASSOCIATED WITH IT WILL STAY WELL NORTH OF THE
AREA. ANOTHER SOUTHERN LOW PRESSURE SYSTEM WHICH WILL MOVE ACROSS
THE SOUTHEAST U.S. DURING THE SAME TIME APPEARS TO BE TOO FAR SOUTH
TO IMPACT POPS HERE. GUIDANCE IS IN GOOD AGREEMENT AND WILL USE AN
AVERAGE WHICH RESULTS IN NEAR NORMAL TEMPERATURES AND DRY WEATHER.
&&
.LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/...
ISSUED AT 248 PM EST TUE JAN 15 2013
FOCUS OF THE EXTENDED PERIOD REMAINS ON THE ARRIVAL OF WHAT
INCREASINGLY APPEARS TO BE THE COLDEST AIRMASS OF THE SEASON AS A
PIEICE OF THE POLAR VORTEX BREAKS OFF AND AMPLIFIES THE UPPER
TROUGH OVER THE EASTERN PART OF THE COUNTRY.
WARMEST DAY OF THE PERIOD WILL BE SATURDAY AS SOUTHERLY FLOW AHEAD
OF A COLD FRONT ENABLES TEMPS TO RISE INTO THE 40S ACROSS THE
FORECAST AREA. LOW PRESSURE WILL TRACK THROUGH THE GREAT LAKES
SATURDAY NIGHT AND BRING THE COLD FRONT THROUGH CENTRAL INDIANA BY
EARLY SUNDAY. THE FRONT WILL USHER IN THE INITIAL SHOT OF COLDER
AIR...AS TEMPS ARE LIKELY TO FALL BACK INTO THE 20S AND LOWER 30S.
PASSAGE OF THE FRONT LOOKS TO BE DRY AS DEEPER MOISTURE IS FOCUSED
CLOSER TO THE LOW ACROSS THE GREAT LAKES. ARCTIC FRONT SET TO DIVE
INTO THE REGION ON MONDAY...USHERING IN MUCH COLDER AIR AS 850MB
TEMPS NOSEDIVE. ANTICIPATE SNOW SHOWERS TO ACCOMPANY THE FRONTAL
PASSAGE AND AS WIND FLOW ALIGNS TO THE NORTHWEST IN ITS WAKE...
LIKELY TO SEE SOME IMPACTS FROM LAKE ENHANCEMENT SNOW SHOWERS
THROUGH MONDAY NIGHT.
THE MUCH GREATER IMPACT WITH THE FRONTAL PASSAGE WILL BE TO
TEMPERATURES AS 850MB TEMPS ON BOTH THE ECMWF AND OP GFS FALL INTO
THE -23 TO -21C RANGE BY TUESDAY. IF THESE NUMBERS EVEN COME CLOSE
TO VERIFYING...HIGH TEMPS ON TUESDAY ARE LIKELY TO STRUGGLE INTO
THE 10-15 DEGREE RANGE AND PROVIDE CENTRAL INDIANA WITH THE
COLDEST AIR OF THE SEASON TO DATE. KNOWING HOW MODELS THIS FAR OUT
TEND TO UNDEROD THE DEPTH OF ARCTIC COLD AND WITH GROWING
CONFIDENCE IN THE INTENSITY OF THE COLD AIRMASS...HAVE CHOSEN TO
UNDERCUT ALLBLEND TEMPS BY 3 TO 4 DEGREES FOR BOTH MONDAY AND
TUESDAY. LOWS MAY BE DOWN NEAR ZERO BY TUESDAY NIGHT.
&&
.AVIATION /DISCUSSION FOR 160000Z TAF ISSUANCE/...
ISSUED AT 508 PM EST TUE JAN 15 2013
NO SIGNIFICANT CHANGES. VFR CONDITIONS ANTICIPATED THROUGHOUT THE
FORECAST PERIOD.
CLOUD COVERAGE WILL CONTINUE TO INCREASE ACROSS CENTRAL INDIANA
AS LOW PRESSURE MOVES OUT OF THE GULF COAST REGION MOVES ACROSS THE
SOUTHERN TENNESSEE VALLEY THIS EVENING. MOISTURE PROFILES HAVE
ALREADY BEGUN TO DEEPEN THIS EVENING WITH CEILINGS AROUND 6-8KFT.
AS THE LOW PRESSURE SHIFTS INTO THE SOUTHERN APPALACHIANS LATE
TONIGHT...MOISTURE ALOFT WILL ALSO BEGIN TO DEPART OFF TO THE EAST
AND CEILINGS ARE EXPECTED TO LIFT AND SCATTER IN THE HOURS
APPROACHING DAYBREAK. HIGH PRESSURE RIDGE THEN BUILDS INTO THE
REGION WEDNESDAY WITH BROAD SUBSIDENCE. WILL SEE SKIES BECOME
MOSTLY CLEAR. LIGHT AND VARIABLE WINDS LATE TONIGHT WILL SHIFT TO
W/SW AND INCREASE TO NEAR 10KTS WEDNESDAY.
&&
.IND WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...CP
NEAR TERM...CP
SHORT TERM...CP
LONG TERM....RYAN
AVIATION...SMF
AREA FORECAST DISCUSSION
NWS INDIANAPOLIS IN
323 PM EST TUE JAN 15 2013
.UPDATE...
THE AVIATION SECTION HAS BEEN UPDATED BELOW.
&&
.SYNOPSIS...
ISSUED AT 212 PM EST TUE JAN 15 2013
QUIET WEATHER CAN BE EXPECTED UNDER HIGH PRESSURE THROUGH THE END
OF THE WEEK WITH TEMPERATURES NEAR NORMAL FOR THIS TIME OF YEAR.
COULD SEE A BRIEF WARM UP SATURDAY INTO THE 40S BEFORE
TEMPERATURES DROP BACK TO NORMAL SUNDAY AND THEN GET VERY COLD TO
START OUT THE WEEK. A CLIPPER SYSTEM WILL MOVE THROUGH SUNDAY
NIGHT THROUGH MONDAY NIGHT BRINGING CHANCES FOR SNOW.
&&
.NEAR TERM /TONIGHT/...
ISSUED AT 212 PM EST TUE JAN 15 2013
SKIES SHOULD START OUT MOSTLY CLOUDY WITH A LOW PRESSURE SYSTEM
MOVING NORTHEAST OUT OF THE GULF AND THROUGH THE SOUTHEASTERN U.S. A
BIT OF MODEL DISAGREEMENT OVER HOW FAR NORTH PRECIPITATION
ASSOCIATED WITH THIS SYSTEM WILL GET DESPITE SIMILAR POSITIONS AND
STRENGTH FOR THE LOW PRESSURE CENTER. THE RAP AND GEM WERE THE
FURTHEST NORTH AND BRING THE PRECIP INTO THE FAR SOUTHEASTERN
COUNTIES. THE GFS KEEPS THE PRECIP WELL TO THE SOUTH...WHILE THE NAM
AND 0Z ECMWF JUST CLIP THE FAR SOUTHEAST WITH A HUNDREDTH OF QPF.
WITH THE VARIETY OF SOLUTIONS SHOULD CARRY A LOW CHANCE POP IN THE
FAR SOUTHEAST WITH DRY WEATHER BUT MOSTLY CLOUDY SKIES ELSEWHERE.
WENT WITH LOWS A DEGREE OR TWO BELOW GUIDANCE WITH EXPECTED COLD
ADVECTION.
&&
.SHORT TERM /WEDNESDAY THROUGH FRIDAY/...
ISSUED AT 212 PM EST TUE JAN 15 2013
HIGH PRESSURE WILL REMAIN OVER THE AREA THROUGH THE SHORT TERM. A
LOW PRESSURE SYSTEM MOVING ACROSS THE HUDSON BAY WILL DRAG A COLD
FRONT ACROSS THE GREAT LAKES WEDNESDAY AND WEDNESDAY NIGHT...BUT IT LOOKS
LIKE ALL THE FORCING ASSOCIATED WITH IT WILL STAY WELL NORTH OF THE
AREA. ANOTHER SOUTHERN LOW PRESSURE SYSTEM WHICH WILL MOVE ACROSS
THE SOUTHEAST U.S. DURING THE SAME TIME APPEARS TO BE TOO FAR SOUTH
TO IMPACT POPS HERE. GUIDANCE IS IN GOOD AGREEMENT AND WILL USE AN
AVERAGE WHICH RESULTS IN NEAR NORMAL TEMPERATURES AND DRY WEATHER.
&&
.LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/...
ISSUED AT 248 PM EST TUE JAN 15 2013
FOCUS OF THE EXTENDED PERIOD REMAINS ON THE ARRIVAL OF WHAT
INCREASINGLY APPEARS TO BE THE COLDEST AIRMASS OF THE SEASON AS A
PIEICE OF THE POLAR VORTEX BREAKS OFF AND AMPLIFIES THE UPPER
TROUGH OVER THE EASTERN PART OF THE COUNTRY.
WARMEST DAY OF THE PERIOD WILL BE SATURDAY AS SOUTHERLY FLOW AHEAD
OF A COLD FRONT ENABLES TEMPS TO RISE INTO THE 40S ACROSS THE
FORECAST AREA. LOW PRESSURE WILL TRACK THROUGH THE GREAT LAKES
SATURDAY NIGHT AND BRING THE COLD FRONT THROUGH CENTRAL INDIANA BY
EARLY SUNDAY. THE FRONT WILL USHER IN THE INITIAL SHOT OF COLDER
AIR...AS TEMPS ARE LIKELY TO FALL BACK INTO THE 20S AND LOWER 30S.
PASSAGE OF THE FRONT LOOKS TO BE DRY AS DEEPER MOISTURE IS FOCUSED
CLOSER TO THE LOW ACROSS THE GREAT LAKES. ARCTIC FRONT SET TO DIVE
INTO THE REGION ON MONDAY...USHERING IN MUCH COLDER AIR AS 850MB
TEMPS NOSEDIVE. ANTICIPATE SNOW SHOWERS TO ACCOMPANY THE FRONTAL
PASSAGE AND AS WIND FLOW ALIGNS TO THE NORTHWEST IN ITS WAKE...
LIKELY TO SEE SOME IMPACTS FROM LAKE ENHANCEMENT SNOW SHOWERS
THROUGH MONDAY NIGHT.
THE MUCH GREATER IMPACT WITH THE FRONTAL PASSAGE WILL BE TO
TEMPERATURES AS 850MB TEMPS ON BOTH THE ECMWF AND OP GFS FALL INTO
THE -23 TO -21C RANGE BY TUESDAY. IF THESE NUMBERS EVEN COME CLOSE
TO VERIFYING...HIGH TEMPS ON TUESDAY ARE LIKELY TO STRUGGLE INTO
THE 10-15 DEGREE RANGE AND PROVIDE CENTRAL INDIANA WITH THE
COLDEST AIR OF THE SEASON TO DATE. KNOWING HOW MODELS THIS FAR OUT
TEND TO UNDEROD THE DEPTH OF ARCTIC COLD AND WITH GROWING
CONFIDENCE IN THE INTENSITY OF THE COLD AIRMASS...HAVE CHOSEN TO
UNDERCUT ALLBLEND TEMPS BY 3 TO 4 DEGREES FOR BOTH MONDAY AND
TUESDAY. LOWS MAY BE DOWN NEAR ZERO BY TUESDAY NIGHT.
&&
.AVIATION /DISCUSSION FOR 152100Z TAF UPDATE/...
ISSUED AT 323 PM EST TUE JAN 15 2013
NO SIGNIFICANT CHANGES...PREVIOUS DICUSSION FOLLOWS.
VFR CONDITIONS ANTICIPATED THROUGHOUT THE FORECAST.
MID AND HIGH LEVEL CLOUD COVERAGE WILL STEADILY INCREASE ACROSS
CENTRAL INDIANA THIS AFTERNOON AS LOW PRESSURE MOVES OUT OF THE
GULF COAST REGION AND INTO THE LOWER TENNESSEE VALLEY THIS
EVENING. LARGE AREA OF CEILINGS AROUND 10KFT OVER THE OZARKS
QUICKLY EXPANDING NORTHEAST AND SHOULD ENVELOP THE TERMINALS BY
MID AFTERNOON. MOISTURE PROFILE DEEPENS THIS EVENING WITH CEILINGS
LIKELY TO FALL TO 6-8KFT FOR SEVERAL HOURS...ESPECIALLY AT KBMG/
KHUF/KIND. BOUNDARY LAYER HOWEVER REMAINS DRY WITH A PERSISTENT
LOW LEVEL FLOW FROM THE NORTHEAST.
AS THE LOW PRESSURE SHIFTS INTO THE SOUTHERN APPALACHIANS LATE
TONIGHT...MOISTURE ALOFT WILL ALSO BEGIN TO DEPART OFF TO THE EAST
AND CEILINGS ARE EXPECTED TO LIFT AND SCATTER IN THE HOURS
APPROACHING DAYBREAK. HIGH PRESSURE RIDGE THEN BUILDS INTO THE
REGION WEDNESDAY WITH BROAD SUBSIDENCE AND WILL SEE SKIES BECOME
MOSTLY CLEAR. LIGHT AND VARIABLE WINDS LATE TONIGHT WILL SHIFT TO
W/SW AND INCREASE TO NEAR 10KTS WEDNESDAY.
&&
.IND WATCHES/WARNINGS/ADVISORIES...NONE.
&&
$$
SYNOPSIS...CP
NEAR TERM...CP
SHORT TERM...CP
LONG TERM....RYAN
AVIATION...RYAN
AREA FORECAST DISCUSSION
NWS INDIANAPOLIS IN
248 PM EST TUE JAN 15 2013
.UPDATE...
THE LONG TERM SECTION HAS BEEN UPDATED BELOW.
&&
.SYNOPSIS...
ISSUED AT 212 PM EST TUE JAN 15 2013
QUIET WEATHER CAN BE EXPECTED UNDER HIGH PRESSURE THROUGH THE END
OF THE WEEK WITH TEMPERATURES NEAR NORMAL FOR THIS TIME OF YEAR.
COULD SEE A BRIEF WARM UP SATURDAY INTO THE 40S BEFORE
TEMPERATURES DROP BACK TO NORMAL SUNDAY AND THEN GET VERY COLD TO
START OUT THE WEEK. A CLIPPER SYSTEM WILL MOVE THROUGH SUNDAY
NIGHT THROUGH MONDAY NIGHT BRINGING CHANCES FOR SNOW.
&&
.NEAR TERM /TONIGHT/...
ISSUED AT 212 PM EST TUE JAN 15 2013
SKIES SHOULD START OUT MOSTLY CLOUDY WITH A LOW PRESSURE SYSTEM
MOVING NORTHEAST OUT OF THE GULF AND THROUGH THE SOUTHEASTERN U.S. A
BIT OF MODEL DISAGREEMENT OVER HOW FAR NORTH PRECIPITATION
ASSOCIATED WITH THIS SYSTEM WILL GET DESPITE SIMILAR POSITIONS AND
STRENGTH FOR THE LOW PRESSURE CENTER. THE RAP AND GEM WERE THE
FURTHEST NORTH AND BRING THE PRECIP INTO THE FAR SOUTHEASTERN
COUNTIES. THE GFS KEEPS THE PRECIP WELL TO THE SOUTH...WHILE THE NAM
AND 0Z ECMWF JUST CLIP THE FAR SOUTHEAST WITH A HUNDREDTH OF QPF.
WITH THE VARIETY OF SOLUTIONS SHOULD CARRY A LOW CHANCE POP IN THE
FAR SOUTHEAST WITH DRY WEATHER BUT MOSTLY CLOUDY SKIES ELSEWHERE.
WENT WITH LOWS A DEGREE OR TWO BELOW GUIDANCE WITH EXPECTED COLD
ADVECTION.
&&
.SHORT TERM /WEDNESDAY THROUGH FRIDAY/...
ISSUED AT 212 PM EST TUE JAN 15 2013
HIGH PRESSURE WILL REMAIN OVER THE AREA THROUGH THE SHORT TERM. A
LOW PRESSURE SYSTEM MOVING ACROSS THE HUDSON BAY WILL DRAG A COLD
FRONT ACROSS THE GREAT LAKES WEDNESDAY AND WEDNESDAY NIGHT...BUT IT LOOKS
LIKE ALL THE FORCING ASSOCIATED WITH IT WILL STAY WELL NORTH OF THE
AREA. ANOTHER SOUTHERN LOW PRESSURE SYSTEM WHICH WILL MOVE ACROSS
THE SOUTHEAST U.S. DURING THE SAME TIME APPEARS TO BE TOO FAR SOUTH
TO IMPACT POPS HERE. GUIDANCE IS IN GOOD AGREEMENT AND WILL USE AN
AVERAGE WHICH RESULTS IN NEAR NORMAL TEMPERATURES AND DRY WEATHER.
&&
.LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/...
ISSUED AT 248 PM EST TUE JAN 15 2013
FOCUS OF THE EXTENDED PERIOD REMAINS ON THE ARRIVAL OF WHAT
INCREASINGLY APPEARS TO BE THE COLDEST AIRMASS OF THE SEASON AS A
PIEICE OF THE POLAR VORTEX BREAKS OFF AND AMPLIFIES THE UPPER
TROUGH OVER THE EASTERN PART OF THE COUNTRY.
WARMEST DAY OF THE PERIOD WILL BE SATURDAY AS SOUTHERLY FLOW AHEAD
OF A COLD FRONT ENABLES TEMPS TO RISE INTO THE 40S ACROSS THE
FORECAST AREA. LOW PRESSURE WILL TRACK THROUGH THE GREAT LAKES
SATURDAY NIGHT AND BRING THE COLD FRONT THROUGH CENTRAL INDIANA BY
EARLY SUNDAY. THE FRONT WILL USHER IN THE INITIAL SHOT OF COLDER
AIR...AS TEMPS ARE LIKELY TO FALL BACK INTO THE 20S AND LOWER 30S.
PASSAGE OF THE FRONT LOOKS TO BE DRY AS DEEPER MOISTURE IS FOCUSED
CLOSER TO THE LOW ACROSS THE GREAT LAKES. ARCTIC FRONT SET TO DIVE
INTO THE REGION ON MONDAY...USHERING IN MUCH COLDER AIR AS 850MB
TEMPS NOSEDIVE. ANTICIPATE SNOW SHOWERS TO ACCOMPANY THE FRONTAL
PASSAGE AND AS WIND FLOW ALIGNS TO THE NORTHWEST IN ITS WAKE...
LIKELY TO SEE SOME IMPACTS FROM LAKE ENHANCEMENT SNOW SHOWERS
THROUGH MONDAY NIGHT.
THE MUCH GREATER IMPACT WITH THE FRONTAL PASSAGE WILL BE TO
TEMPERATURES AS 850MB TEMPS ON BOTH THE ECMWF AND OP GFS FALL INTO
THE -23 TO -21C RANGE BY TUESDAY. IF THESE NUMBERS EVEN COME CLOSE
TO VERIFYING...HIGH TEMPS ON TUESDAY ARE LIKELY TO STRUGGLE INTO
THE 10-15 DEGREE RANGE AND PROVIDE CENTRAL INDIANA WITH THE
COLDEST AIR OF THE SEASON TO DATE. KNOWING HOW MODELS THIS FAR OUT
TEND TO UNDEROD THE DEPTH OF ARCTIC COLD AND WITH GROWING
CONFIDENCE IN THE INTENSITY OF THE COLD AIRMASS...HAVE CHOSEN TO
UNDERCUT ALLBLEND TEMPS BY 3 TO 4 DEGREES FOR BOTH MONDAY AND
TUESDAY. LOWS MAY BE DOWN NEAR ZERO BY TUESDAY NIGHT.
&&
.AVIATION /DISCUSSION FOR 151800Z TAF ISSUANCE/...
ISSUED AT 1153 AM EST TUE JAN 15 2013
VFR CONDITIONS ANTICIPATED THROUGHOUT THE FORECAST.
MID AND HIGH LEVEL CLOUD COVERAGE WILL STEADILY INCREASE ACROSS
CENTRAL INDIANA THIS AFTERNOON AS LOW PRESSURE MOVES OUT OF THE
GULF COAST REGION AND INTO THE LOWER TENNESSEE VALLEY THIS
EVENING. LARGE AREA OF CEILINGS AROUND 10KFT OVER THE OZARKS
QUICKLY EXPANDING NORTHEAST AND SHOULD ENVELOP THE TERMINALS BY
MID AFTERNOON. MOISTURE PROFILE DEEPENS THIS EVENING WITH CEILINGS
LIKELY TO FALL TO 6-8KFT FOR SEVERAL HOURS...ESPECIALLY AT KBMG/
KHUF/KIND. BOUNDARY LAYER HOWEVER REMAINS DRY WITH A PERSISTENT
LOW LEVEL FLOW FROM THE NORTHEAST.
AS THE LOW PRESSURE SHIFTS INTO THE SOUTHERN APPALACHIANS LATE
TONIGHT...MOISTURE ALOFT WILL ALSO BEGIN TO DEPART OFF TO THE EAST
AND CEILINGS ARE EXPECTED TO LIFT AND SCATTER IN THE HOURS
APPROACHING DAYBREAK. HIGH PRESSURE RIDGE THEN BUILDS INTO THE
REGION WEDNESDAY WITH BROAD SUBSIDENCE AND WILL SEE SKIES BECOME
MOSTLY CLEAR. LIGHT AND VARIABLE WINDS LATE TONIGHT WILL SHIFT TO
W/SW AND INCREASE TO NEAR 10KTS WEDNESDAY.
&&
.IND WATCHES/WARNINGS/ADVISORIES...NONE.
&&
$$
SYNOPSIS...CP
NEAR TERM...CP
SHORT TERM...CP
LONG TERM....RYAN
AVIATION...RYAN
AREA FORECAST DISCUSSION
NWS INDIANAPOLIS IN
215 PM EST TUE JAN 15 2013
.UPDATE...
THE SYNOPSIS...NEAR TERM AND SHORT TERM SECTIONS HAVE BEEN UPDATED BELOW
&&
.SYNOPSIS...
ISSUED AT 212 PM EST TUE JAN 15 2013
QUIET WEATHER CAN BE EXPECTED UNDER HIGH PRESSURE THROUGH THE END
OF THE WEEK WITH TEMPERATURES NEAR NORMAL FOR THIS TIME OF YEAR.
COULD SEE A BRIEF WARM UP SATURDAY INTO THE 40S BEFORE
TEMPERATURES DROP BACK TO NORMAL SUNDAY AND THEN GET VERY COLD TO
START OUT THE WEEK. A CLIPPER SYSTEM WILL MOVE THROUGH SUNDAY
NIGHT THROUGH MONDAY NIGHT BRINGING CHANCES FOR SNOW.
&&
.NEAR TERM /TONIGHT/...
ISSUED AT 212 PM EST TUE JAN 15 2013
SKIES SHOULD START OUT MOSTLY CLOUDY WITH A LOW PRESSURE SYSTEM
MOVING NORTHEAST OUT OF THE GULF AND THROUGH THE SOUTHEASTERN U.S. A
BIT OF MODEL DISAGREEMENT OVER HOW FAR NORTH PRECIPITATION
ASSOCIATED WITH THIS SYSTEM WILL GET DESPITE SIMILAR POSITIONS AND
STRENGTH FOR THE LOW PRESSURE CENTER. THE RAP AND GEM WERE THE
FURTHEST NORTH AND BRING THE PRECIP INTO THE FAR SOUTHEASTERN
COUNTIES. THE GFS KEEPS THE PRECIP WELL TO THE SOUTH...WHILE THE NAM
AND 0Z ECMWF JUST CLIP THE FAR SOUTHEAST WITH A HUNDREDTH OF QPF.
WITH THE VARIETY OF SOLUTIONS SHOULD CARRY A LOW CHANCE POP IN THE
FAR SOUTHEAST WITH DRY WEATHER BUT MOSTLY CLOUDY SKIES ELSEWHERE.
WENT WITH LOWS A DEGREE OR TWO BELOW GUIDANCE WITH EXPECTED COLD
ADVECTION.
&&
.SHORT TERM /WEDNESDAY THROUGH FRIDAY/...
ISSUED AT 212 PM EST TUE JAN 15 2013
HIGH PRESSURE WILL REMAIN OVER THE AREA THROUGH THE SHORT TERM. A
LOW PRESSURE SYSTEM MOVING ACROSS THE HUDSON BAY WILL DRAG A COLD
FRONT ACROSS THE GREAT LAKES WEDNESDAY AND WEDNESDAY NIGHT...BUT IT LOOKS
LIKE ALL THE FORCING ASSOCIATED WITH IT WILL STAY WELL NORTH OF THE
AREA. ANOTHER SOUTHERN LOW PRESSURE SYSTEM WHICH WILL MOVE ACROSS
THE SOUTHEAST U.S. DURING THE SAME TIME APPEARS TO BE TOO FAR SOUTH
TO IMPACT POPS HERE. GUIDANCE IS IN GOOD AGREEMENT AND WILL USE AN
AVERAGE WHICH RESULTS IN NEAR NORMAL TEMPERATURES AND DRY WEATHER.
&&
.LONG TERM /FRIDAY THROUGH MONDAY/...
ISSUED AT 343 AM EST TUE JAN 15 2013
MAIN FOCUS ON THE EXTENDED WILL BE ON LATE WEEKEND ARCTIC AIR
INVASION.
THE 00Z GFS HAS CONTINUED TO BE MORE AGGRESSIVE IN BRINGING WESTERN
LOBE OF THE POLAR VORTEX SOUTHEAST ACROSS THE FORECAST AREA LATE IN
THE WEEKEND COMPARED TO THE OPERATIONAL 00Z ECMWF. USUALLY WITH
DIFFERENCES IN THE DETERMINISTIC MODELS...BETTER TO SIDE WITH THE
ENSEMBLE MEANS AS A COMPROMISE AND ACCEPT REGIONAL INITIALIZATION
TEMPERATURES WHICH START OFF ABOVE NORMAL WITH LOW LEVEL SOUTHWEST
FLOW AND ZONAL FLOW ALOFT. HOWEVER...ARCTIC FRONT DROPS SOUTH ACROSS
THE FORECAST AREA ON SATURDAY NIGHT BRINGING IN SLIGHTLY BELOW
NORMAL TEMPERATURES BY SUNDAY AND MUCH COLDER TEMPERATURES BY
MONDAY. BY TUESDAY...HIGHS WILL MOSTLY ONLY BE IN THE TEENS WITH
OVERNIGHT LOWS IN THE SINGLE DIGITS BY MONDAY NIGHT. POLAR VORTEX
LOBE COULD ALSO BRING A FEW SNOW SHOWERS TO MAINLY THE NORTHERN
FORECAST AREA BY SUNDAY NIGHT.
&&
.AVIATION /DISCUSSION FOR 151800Z TAF ISSUANCE/...
ISSUED AT 1153 AM EST TUE JAN 15 2013
VFR CONDITIONS ANTICIPATED THROUGHOUT THE FORECAST.
MID AND HIGH LEVEL CLOUD COVERAGE WILL STEADILY INCREASE ACROSS
CENTRAL INDIANA THIS AFTERNOON AS LOW PRESSURE MOVES OUT OF THE
GULF COAST REGION AND INTO THE LOWER TENNESSEE VALLEY THIS
EVENING. LARGE AREA OF CEILINGS AROUND 10KFT OVER THE OZARKS
QUICKLY EXPANDING NORTHEAST AND SHOULD ENVELOP THE TERMINALS BY
MID AFTERNOON. MOISTURE PROFILE DEEPENS THIS EVENING WITH CEILINGS
LIKELY TO FALL TO 6-8KFT FOR SEVERAL HOURS...ESPECIALLY AT KBMG/
KHUF/KIND. BOUNDARY LAYER HOWEVER REMAINS DRY WITH A PERSISTENT
LOW LEVEL FLOW FROM THE NORTHEAST.
AS THE LOW PRESSURE SHIFTS INTO THE SOUTHERN APPALACHIANS LATE
TONIGHT...MOISTURE ALOFT WILL ALSO BEGIN TO DEPART OFF TO THE EAST
AND CEILINGS ARE EXPECTED TO LIFT AND SCATTER IN THE HOURS
APPROACHING DAYBREAK. HIGH PRESSURE RIDGE THEN BUILDS INTO THE
REGION WEDNESDAY WITH BROAD SUBSIDENCE AND WILL SEE SKIES BECOME
MOSTLY CLEAR. LIGHT AND VARIABLE WINDS LATE TONIGHT WILL SHIFT TO
W/SW AND INCREASE TO NEAR 10KTS WEDNESDAY.
&&
.IND WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...CP
NEAR TERM...CP
SHORT TERM...CP
LONG TERM....MK
AVIATION...RYAN
AREA FORECAST DISCUSSION
NWS TOPEKA KS
315 PM CST TUE JAN 15 2013
.DISCUSSION...
20Z WATER VAPOR SHOWS THE TROUGH AXIS OVERHEAD WITH THE UPPER
FLOW BEGINNING TO SPLIT WITH ENERGY BEING LEFT BEHIND OVER THE
SOUTHERN HIGH PLAINS. AT THE SURFACE...THE RIDGE AXIS STRETCHED
FROM THE TX PANHANDLE UP TO CHICAGO. THERE IS A MAXIMUM IN SURFACE
DEWPOINTS IMMEDIATELY DOWNSTREAM OF THE SNOW PACK IN SOUTHERN NEB.
WITH DAYTIME HEATING STEEPENING UP LOW LEVEL LAPSE RATES WITH
ADDED BOUNDARY LAYER MOISTURE...A CU FIELD HAS FORMED OVER NORTH
CENTRAL KS. WOULD EXPECT THESE CLOUDS TO DIMINISH WITH THE LOSS OF
DAYTIME HEATING AND THE 19Z RAP AND 18Z NAM SEEM TO SUPPORT THIS
IDEA...SO THINK SKIES SHOULD BECOME MOSTLY CLEAR OVERNIGHT.
FOR TONIGHT AND WEDNESDAY...THE FORECAST AREA IS EXPECTED TO BE
BETWEEN THE SPLITTING PATTERN WITH A CLOSED LOW REMAINING OVER THE
SOUTHERN PLAINS AND STRONG NORTHWEST FLOW REMAINING NORTH OVER THE
DAKOTAS AND UPPER MIDWEST. THEREFORE THERE IS EXPECTED TO BE LITTLE
OR NOW LARGE SCALE FORCING AFFECTING THE FORECAST AREA. WITH THIS
AND A DRY AIRMASS TO START OUT WITH...THE FORECAST REMAINS DRY.
THERE WILL BE A TROUGH AXIS/WIND SHIFT MOVE THROUGH THE AREA ON
WEDNESDAY. MODELS DO NOT SHOW ANY COLD AIR BEHIND THIS BOUNDARY AND
IN FACT HAVE WARM AIR ADVECTING IN FROM THE WEST WITH A DOWNSLOPE
WIND. THEREFORE HAVE CONTINUED WITH HIGHS GENERALLY AROUND 50. THERE
IS INDICATIONS FROM THE NAM AND GFS OF SOME SATURATED AIR BEHIND THE
FRONT WHICH COULD BE HELPED BY MELTING SNOW IN NEB...SO THINK SKIES
COULD BECOME PARTLY CLOUDY AS WINDS SHIFT TO THE WEST AND NORTHWEST.
THE PRESSURE GRADIENT SHOULD INCREASE OVERNIGHT AS THE SURFACE
TROUGH APPROACHES THE AREA. THIS SHOULD CAUSE WINDS TO GRADUALLY
INCREASE OVERNIGHT HELPING TO KEEP MIN TEMPS SEVERAL DEGREES WARMER
THAN THIS MORNING AND HAVE MIN TEMPS IN THE UPPER TEENS.
WOLTERS
CLEAR SKIES TO BE THE RULE THROUGH EARLY NEXT WEEK WITH NORTHWEST
FLOW ALOFT KEEPING MOISTURE RETURN IN CHECK AND MEAGER FORCING
MECHANISMS FOR CLOUDS LET ALONE PRECIPITATION. WEAK SURFACE HIGH
BUILDS IN THURSDAY WITH ACTUALLY A BIT OF WARMING AROUND
850MB...BUT THE LIMITED MIXING SHOULD KEEP HIGHS A FEW DEGREES
COOLER THAN WEDNESDAY. FRIDAY STILL LOOKING THE BE THE WARMEST DAY
WITH WEST TO SOUTHWEST WINDS DEVELOPING AHEAD OF A WAVE IN THE GREAT
LAKES. SATURDAY WILL SEE THE FIRST OF TWO COLD FRONTS MOVE IN DURING
THE DAY. MID TO LATE DAY COLD AIR ADVECTION SHOULD KEEP HIGHS IN THE
40S...WITH A MORE POTENT SHOT COMING IN THE SUNDAY NIGHT INTO MONDAY
TIME FRAME. THERE HAS BEEN SOME VACILLATION IN THE MODELS WITH HOW
FAR SOUTHWEST THE COLD AIR WILL REACH AND SPECIFIC TIMING OF THE
COLD AIR REMAINS UNCERTAIN. ALSO...THERE IS GOOD AGREEMENT WITH THE
UPPER PATTERN BREAKING DOWN TO A MORE ZONAL CHARACTER AS THE EASTERN
PACIFIC RIDGE BREAKS DOWN LEADING TO THE COLDEST AIR/S RESIDENCE
TIME IN THE CENTRAL PLAINS LIMITED. MONDAYS MAXES IN THE UPPER TEENS
TO MID 20S SEEM REASONABLE AT THIS POINT WITH MODIFICATION FOR
TUESDAY.
65
&&
.AVIATION...
DRY AIR AND NO FORCING WILL LEAD TO VFR CONDITIONS PREVAILING
THROUGH TONIGHT. A WEAK WIND SHIFT SHOULD MOVE THROUGH THE TERMINALS
BY EARLY AFTERNOON WEDNESDAY. MODELS ARE SUGGESTING A BRIEF PERIOD
OF CIGS BETWEEN 2 AND 3 KFT JUST BEHIND THE FRONT. HAVE NOT ACTED ON
THIS SINCE IT IS NEAR THE END OF THE FORECAST PERIOD...AND THIS
SHOULD ALLOW LATER SHIFTS TO LOOK AT FUTURE GUIDANCE TO SEE IF
MODELS ARE PERSISTENT WITH THE CIGS.
WOLTERS
&&
.TOP WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS GOODLAND KS
212 PM MST TUE JAN 15 2013
.SHORT TERM...(THIS AFTERNOON THROUGH WEDNESDAY)
ISSUED AT 212 PM MST TUE JAN 15 2013
LATEST WV IMAGERY AND RUC H5 ANALYSIS SHOWS LONGWAVE TROUGH EXTENDING
FROM THE GREAT LAKES ACROSS CENTRAL KANSAS INTO NORTHERN MEXICO. CWA
IS CURRENTLY ON SUBSIDENT SIDE OF TROUGH AXIS UNDER SHORTWAVE
RIDGING. A WEAK SHORTWAVE TROUGH OVER MONTANA IS CURRENTLY MOVING
THROUGH N/NW FLOW ALONG THE BACK SIDE OF THE TROUGH.
THIS FEATURE IS EXPECTED TO SPLIT WITH A WEAK PIECE OF ENERGY MOVING
SOUTH ACROSS EASTERN COLORADO TONIGHT. WITH MAIN H3 JET AXIS WELL
NORTH OF THE CWA...I AM ONLY ANTICIPATING WEAK FORCING. MODEL
SOUNDINGS INDICATE A SATURATED LEVEL BETWEEN 800-600MB. WITH WEAK
FORCING IN THE WEST...AND VERY LITTLE IN THE WAY OF QPF SHOWN BY
AVAILABLE GUIDANCE I LIMITED SLIGHT CHANCE POPS TO WESTERN CWA THIS
EVENING AND OVERNIGHT...AND SCATTERED FLURRIES ELSEWHERE. EVEN IN
THE WEST WHERE MEASURABLE SNOW IS POSSIBLE I WOULD ONLY ANTICIPATE
A FEW TENTHS OF AN INCH WITH THIS SYSTEM.
SUBSIDENCE ALONG AND A MUCH DRIER AIR MASS WILL SPREAD EAST
WEDNESDAY WITH W/NW FLOW DEVELOPING. AIR MASS HAS ALREADY MODIFIED
WITH SHORTWAVE RIDGING THIS AFTERNOON AND SHOULD CONTINUE TO MODIFY
WED WITH HIGHS IN THE 40S/NEAR 50. THE SNOW PACK IN THE WEST AND NE
WILL STILL KEEP HIGHS SLIGHTLY COOLER...HOWEVER WITH WESTERLY WINDS
WE SHOULD STILL SEE HIGHS AROUND 40F AT THE COLDEST. A CONCERN FOR
WED WILL BE WINDS...WITH BREEZY TO WINDY CONDITIONS ANTICIPATED. I
AM LESS CONFIDENT HOW WINDY IT WILL BE WITH LIMITED MIXING HEIGHTS
BASED ON SOUNDING ANALYSIS. IF WE MIX MUCH HIGHER THAN CURRENT
SOUNDINGS SUGGEST...THEN WE COULD SEE ADVISORY CRITERIA MET...
ESPECIALLY IF WE USE THE NAM WINDS ALOFT. FOR NOW...I LIMITED WINDS
TO JUST UNDER ADVISORY CRITERIA WED AFTERNOON.
.LONG TERM...(WEDNESDAY NIGHT THROUGH TUESDAY)
ISSUED AT 212 PM MST TUE JAN 15 2013
FORECAST PROBLEMS WILL BE THE AMOUNT OF WARMUP BEFORE THE NEXT VERY
COLD AIR MASS ARRIVES AND HOW COLD WILL THAT AIR MASS ALONG WITH
WHEN IT ARRIVES. SATELLITE SHOWING AN AMPLIFIED FLOW STARTING WITH
A BROAD...DEEP AND COMPLICATED UPPER TROUGH OVER THE WESTERN HALF OF
THE PACIFIC WHICH IS MAINTAINING/AMPLIFYING AN UPPER RIDGE NEAR THE
WEST COAST OF NORTH AMERICA. THIS TRANSITIONS TO A TROUGH OVER THE
CENTER OF THE COUNTRY WHICH HAS/CONTINUES TO SPLIT. WARMER AIR MASS
STARTING TO WORK ITS WAY INTO THE REGION.
AT JET LEVEL...THE MODELS INITIALIZED FINE WITH THE ECMWF SLIGHTLY
WORSE THAN THE OTHERS. SATELLITE AND UPPER AIR ANALYSIS SHOW THE
MODELS HAVE INITIALIZED WELL AT MID LEVELS. HOWEVER WOULD HAVE TO
SLIGHTLY FAVOR THE UKMET/CANADIAN OVER THE NAM/ECMWF. AT THE
SURFACE THE SREF WAS DOING A LITTLE BETTER THAN THE ECMWF. THE UKMET
WAS DOING A LITTLE BETTER THAN THE ECMWF AND GFS ON THE LOW LEVEL
THERMAL FIELD.
WEDNESDAY NIGHT/THURSDAY...MAIN STORM TRACK REMAINS WELL NORTH OF
THE AREA AND UNDER SUBSIDENCE FROM THE JET. FLOW ALOFT IS MORE
NORTHWEST WITH LITTLE TO NO CLOUD COVER EXPECTED AT THIS TIME.
WINDS MAY DROP OFF LATE IN THE NIGHT MAINLY IN THE WEST. SURFACE
RIDGE MOVES THROUGH EARLY IN THE DAY ON THURSDAY WITH WINDS SHIFTING
MORE TOWARD THE SOUTH IN THE AFTERNOON. ADJUSTED TEMPERATURES UP A
LITTLE.
THURSDAY NIGHT/FRIDAY...STORM TRACK STILL NORTH OF THE AREA WITH
WEST TO NORTHWEST FLOW ALOFT. THERE MAY BE A LITTLE MORE CLOUD
COVER DURING THE NIGHT AS A WEAK SYSTEM MOVES THROUGH IN THE FLOW
BUT AGAIN LITTLE TO NO CLOUD COVER EXPECTED. DOWNSLOPE COMPONENT IS
MUCH BETTER ON THE WINDS AND ALL MODELS ARE SIMILAR IN THEIR INCREASE
IN THE 850 MB TEMPERATURES. ALSO WOULD EXPECT THE WARM AIR ADVECTION
AND DOWNSLOPE WILL BE BETTER THAN DEPICTED SINCE THIS WILL BE AHEAD
OF THE INITIAL PUSH OF COLDER THAT WILL COME IN ON SATURDAY. SO FELT
COMFORTABLE IN WARMING UP MAXES FROM THE CURRENT PACKAGE. IT IS
POSSIBLE THAT ADDITIONAL RAISING OF THE MAXES WILL BE POSSIBLE.
FRIDAY NIGHT THROUGH TUESDAY...BIG CHANGE IN THE WEATHER...TO MUCH
COLDER TEMPERATURES THIS WEEKEND INTO THE BEGINNING OF NEXT WEEK...
STILL LOOKS ON TRACK. THERE ARE STILL DIFFERENCES IN THE MODELS BUT
THEY ARE MUCH CLOSER THAN YESTERDAY WHICH INCREASES CONFIDENCE ON
THE MAGNITUDE AND ESPECIALLY THE TIMING. SATURDAY LOOKS TO BE VERY
TRICKY. THE INITIAL PUSH IS COMING IN A LITTLE FASTER AND LOOKS
LIKE IT MAY ARRIVE LATE MORNING INTO EARLY AFTERNOON ESPECIALLY IN
THE NORTHEAST HALF OF THE AREA. SO THERE LOOKS TO BE A GOOD GRADIENT
ACROSS MY AREA WHICH WILL NEED TO BE RESOLVED AS WE GET MUCH CLOSER
TO THE DAY. AT THIS TIME TOOK WHAT WAS GIVEN TO ME BY THE CRH_INIT
AND NUDGED DOWN A LITTLE AS I BLENDED WITH NEIGHBORS.
FIRST PUSH OF THE COLD AIR LOOKS TO BE WELL ENTRENCHED BY 12Z
SUNDAY. MODELS WANT TO SCOUR OUT THE COLD AIR DURING THE DAY AS WINDS
SHIFT TO THE WEST BEFORE THE COLDEST AIR ARRIVES SUNDAY NIGHT. NOT
ENTIRELY SOLD ON THAT. SO AFTER COLLABORATION WITH NEIGHBORS DID
LOWER MAXES FROM WHAT WAS GIVEN BY THE INIT. VERY COLD AIR TO
ARRIVE SUNDAY NIGHT INTO MONDAY PER MODEL CONSENSUS. AFTER
COLLABORATION FELT VERY COMFORTABLE IN LOWERING MAXES SIGNIFICANTLY.
WHEN THE COLD AIR COMES IN SUNDAY NIGHT AND MONDAY FLURRIES WILL BE
POSSIBLE. THEN MODELS WANT TO REALLY SCOUR OUT THE COLD AIR ON
TUESDAY AND AGAIN NOT SOLD ON THAT. HOWEVER...THE INIT GAVE ME COOLER
TEMPERATURES THAN WHAT THE MODEL 850 TEMPERATURES SAY. SO AGREED WITH
SURROUNDING OFFICES IN LEAVING THOSE TEMPERATURES ALONE FOR NOW.
THANKS TO ALL FOR THE COLLABORATION.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z WEDNESDAY AFTERNOON)
ISSUED AT 1039 AM MST TUE JAN 15 2013
VFR CONDITIONS WILL PERSIST THROUGH THE NEXT 24 HOURS AT BOTH GLD
AND MCK...WITH A SMALL CHANCE FOR A SHORT PERIOD OF MVFR CEILINGS AT
EITHER SITE. SKIES ARE CLEAR AT THE MOMENT BUT MID-LEVEL CLOUDS WILL
INCREASE LATER THIS AFTERNOON ASSOCIATED WITH AN UPPER DISTURBANCE
THAT WILL MOVE THROUGH BOTH SITES QUICKLY TONIGHT. THERE IS A CHANCE
FOR FLURRIES OR LIGHT SNOW...BUT AM NOT CONFIDENT THAT PRECIPITATION
WILL REACH EITHER TERMINAL. CEILINGS WILL APPROACH MVFR AT
TIMES...WITH SKIES CLEARING BY EARLY TOMORROW MORNING. WINDS OVER
THE PERIOD WILL BEGIN LIGHT OUT OF THE WEST...BECOMING STRONGER
BEHIND THE DISTURBANCE WITH GUSTS UP TO 25KTS OUT OF THE
NORTHWEST.
&&
.GLD WATCHES/WARNINGS/ADVISORIES...
KS...NONE.
CO...NONE.
NE...NONE.
&&
$$
SHORT TERM...DR
LONG TERM...BULLER
AVIATION...JJM
AREA FORECAST DISCUSSION
NWS GAYLORD MI
108 PM EST TUE JAN 15 2013
.SYNOPSIS...
ISSUED AT 346 AM EST TUE JAN 15 2013
SEVERAL AREAS OF LOW PRESSURE AND COLD FRONTS WILL CROSS NORTHERN
MICHIGAN OVER THE NEXT SEVERAL DAYS. THIS WILL PRODUCE PERIODS OF
LAKE EFFECT AND LAKE ENHANCED SNOW SHOWERS...WHICH WILL PRIMARILY
AFFECT EASTERN UPPER AND NORTHWEST LOWER MICHIGAN.
&&
.UPDATE...
ISSUED AT 1257 PM EST TUE JAN 15 2013
CURRENT FORECAST IN GOOD SHAPE WITH CLOUDS DEVELOPING CLOSER TO
LAKE MICHIGAN AND A GOOD AMOUNT OF SUNSHINE INLAND. STILL THINK A
FEW FLURRIES OR LIGHT SNOW SHOWERS ARE LIKELY CLOSER TO THE
LAKE MICHIGAN SHORELINE THIS AFTERNOON...DESPITE ONLY MARGINAL
MOISTURE. ALSO MADE A FEW SMALL ADJUSTMENTS TO TEMPERATURES BASED
ON LATEST OBSERVATIONS.
OTHERWISE...FEW CHANGES TO CURRENT FORECAST FOR THE AFTERNOON
HOURS.
UPDATE ISSUED AT 935 AM EST TUE JAN 15 2013
STRATO-CU HAS LARGELY ERODED THIS MORNING AS DEEP DRY AIR ABOVE
850MB MIXES OUT LOW LEVEL MOISTURE. STILL SEEING AN AREA OF LOW
LEVEL MOISTURE HUGGING THE LAKE MICHIGAN SHORELINE FROM FRANKFORT
SOUTHWARD. WILL LARGELY DISREGARD THE "MOIST" NAM TODAY...WHICH
IS MUCH TOO PESSIMISTIC WITH WIDESPREAD CLOUDINESS ACROSS
NORTHERN MICHIGAN THIS AFTERNOON. COMBO OF LINGERING LOW LEVEL
MOISTURE ALONG THE COASTLINE AND A FEW UPSTREAM PATCHES OF MID
CLOUD OVER WISCONSIN MAY INTERACT WITH STILL PLENTIFUL OVERLAKE
INSTABILITY TO PRODUCE A FEW AFTN FLURRIES CLOSER TO THE LAKE
MICHIGAN COAST. INLAND AREAS SHOULD SEE A GOOD AMOUNT OF SUNSHINE.
CURRENT TEMP FORECAST LOOKS GOOD AND WILL MAKE ONLY SOME MINOR
CHANGES BASED ON CURRENT OBSERVATIONS.
UPDATE ISSUED AT 639 AM EST TUE JAN 15 2013
BIG UPDATES EARLY THIS MORNING...AS THE STRATO CU OFF THE LAKES
HAS RAPIDLY ERODED...LEAVING CLEARING SKIES MOST AREAS...WITH ONLY
SOME SCATTERED FLURRIES. WITH NO DISCERNIBLE MID LEVEL CLOUD
UPSTREAM...OUTSIDE OF A SMALL AREAS IN NORTH CENTRAL
WISCONSIN...WILL DISREGARD NAM/GFS TRAPPED IN SHALLOW STRATO CU
MOSTLY CLOUDY SKY FOR THE DAY. RATHER...WILL OPT TO KEEP SKIES ON
THE CLEARER SIDE FOR THE DAY. THIS AGREED UPON BY LATEST RUC DATA.
AS WINDS INCREASE TONIGHT...MAYBE SOME ADDITIONAL MOISTURE FLUX
OFF THE LAKES...BUT EVEN HERE...DATA SUGGESTS THAT THE ATMOSPHERE
DRIES OUT LATE...PRIOR TO NEXT UPSTREAM CLIPPER/COLD FRONT SET FOR
WEDNESDAY.
&&
.SHORT TERM...(TODAY THROUGH TONIGHT)
ISSUED AT 346 AM EST TUE JAN 15 2013
EARLY MORNING REGIONAL ANALYSIS SHOWS HIGH PRESSURE STRETCHED OUT
ACROSS THE WESTERN LAKES ON FRONT SIDE OF POSITIVELY TILTED DEEP MID
LEVEL TROUGH AXIS EXTENDING FROM HUDSON BAY DOWN TO NEAR THE FOUR
CORNERS. LIGHT WSW FLOW CONTINUES TO ROTATE AROUND NORTH EDGE OF
SURFACE RIDGE AXIS ACROSS THE NORTHERN LAKES. THIS...COMBINED WITH
MORE THAN SUFFICIENT DELTA T/S (RAP ANALYSIS SHOWS H85 TEMPS IN THE
NEGATIVE MID TEENS) AND SLIGHT UPTICK IN LOW LEVEL MOISTURE...HAS
KICKED OFF GENERALLY LIGHT LAKE INDUCED SNOWS ACROSS NORTHWEST LOWER
MICHIGAN. NICE FLUFF FACTOR...HOWEVER...WITH LAKE INDUCED MOISTURE
AXIS REMAINING PEGGED IN THE DGZ...AS NOTED BY LARGE DENDRITIC
CONGLOMERATES FALLING HERE AT THE OFFICE. NO REPORTS YET...BUT NO
DOUBT AT LEAST SOME LIGHT ACCUMULATIONS OCCURRING UNDER WEAK BANDING
STRUCTURES. FORECAST CONCERNS THROUGH THE SHORT TERM CONTINUE TO
CENTER ON MESOSCALE LAKE SNOW TRENDS.
MARGINAL LAKE PROCESSES TO CONTINUE THROUGH TODAY AS SUFFICIENT
LAKE/AIR TEMPERATURE DIFFERENCE REMAINS PARTIALLY OFFSET BY LOW
INVERSION HEIGHTS AND LIMITED MOISTURE. MODEL DERIVED SOUNDINGS
CONCUR...WITH NOTED INVERTED-V DEVELOPMENT IN SURFACE BASED
ENVIRONMENT AS UPSTREAM DRY SURGE REPLACES CURRENT UPTICK IN LOW
LEVEL MOISTURE. "BEST" ACTIVITY EXPECTED EARLY ON THIS MORNING IN
FAVORED W TO WSW FLOW REGIMES OF NORTHWEST LOWER...WITH PERHAPS AN
ADDITIONAL INCH OR TWO UNDER THE MORE PERSISTENT BANDS. MUCH LIKE
YESTERDAY...EXPECT A DOWNWARD TREND IN BOTH INTENSITY AND COVERAGE
THROUGH THE DAY AS FLOW ONCE AGAIN BACKS AROUND TO SOUTHWEST BY THIS
AFTERNOON. POSSIBLY THINGS MAY END ALL TOGETHER (ALSO LIKE
YESTERDAY)...BUT DON`T WANT TO GO THIS OPTIMISTIC JUST YET. EITHER
WAY...NOT A BIG DEAL THIS AFTERNOON WITH ANY SNOW AMOUNTS LIKELY
REMAINING VERY LIGHT. NOT TOO SHABBY OF A DAY AWAY FROM THE FAVORED
LAKE PRONE AREAS OF NORTHWEST LOWER/SOUTHERN PORTIONS OF EASTERN
UPPER...WITH PARTLY TO MOSTLY CLOUDY SKIES AND TEMPERATURES IN THE
20S.
STORY REMAINS UNCHANGED THROUGH THIS EVENING WITH MARGINAL
INSTABILITY KICKING OFF SCATTERED LIGHT SNOW SHOWERS IN SOUTHWEST
FLOW AREAS. ALBERTA CLIPPER/COLD FRONT APPROACH THE WESTERN LAKES
LATE...WITH TRENDS SUPPORTING ATTENDANT MOISTURE AXIS NOT REACHING
OUR AREA UNTIL AFTER SUNRISE. WEAK PRE-FRONTAL WAA AND CONTINUOUS
FEED OF LOW LEVEL DRY AIR SHOULD CONTINUE TO SUBSTANTIALLY HINDER
LAKE PROCESSES THROUGH THE OVERNIGHT...DESPITE STEADY UPTICK IN
OVER-WATER WIND SPEEDS. EXPECT ANY SNOWFALL AMOUNTS TO REMAIN UNDER
AN INCH. UPTICK IN WINDS UNDER INCREASING PRESSURE GRADIENT REGIME
WILL OFFSET PARTLY TO MOSTLY CLEAR SKIES ELSEWHERE...NOT ALLOWING
TEMPERATURES TO DROP TOO MUCH. INHERITED LOW IN THE TEENS AND 20S
LOOK GREAT.
.LONG TERM...(WEDNESDAY THROUGH MONDAY)
ISSUED AT 346 AM EST TUE JAN 15 2013
WEDNESDAY AND WEDNESDAY NIGHT...UPPER LEVEL TROUGHING WILL BE
SITUATED OVER THE NRN GREAT LAKES...SHARPENED BY SHORTWAVE ENERGY
DIVING INTO THE REGION. THE ASSOCIATED CLIPPER/LOW PRESSURE WILL
PASS THROUGH ONTARIO...WITH A FAIRLY STRONG COLD FRONT TO CROSS
NRN MICHIGAN WEDNESDAY NIGHT. SW WINDS AHEAD OF THE FRONT WILL
GRADUALLY SHIFT AROUND TO OUT OF THE NW BY THURSDAY MORNING.
ENHANCED MOISTURE WITH THE FRONT WILL BRING SOME LIGHT SYNOPTIC
SNOWS WEDNESDAY...ENHANCED TO A MARGINAL DEGREE BY H8 TEMPS OF
-8C. NOT IMPRESSED WITH THE SNOWFALL INTENSITIES...AS INVERSION
HEIGHTS ONLY BRIEFLY RISE TO 5KFT...WITH WSW FLOW POINTING BEST
SNOWS ALONG FAR NW LOWER AND INTO EASTERN UPPER. LOWERED SNOWFALL
AMOUNTS BASED ON TURNING WINDS...AND ONLY A BRIEF PERIOD OF MORE
MODERATE ACTIVITY WITH THE FRONT. SECONDARY SHORTWAVE ENERGY AND
DEEPER MOISTURE WILL ENHANCE SNOW SHOWERS AT NIGHT...WHILE H8
TEMPS PLUMMET TO -22C NORTH/-16C SOUTH. AGAIN...WINDS ARE SHIFTING
OVER TIME...WITH INVERSION HEIGHTS 5KFT NORTH TO 4000 FEET SOUTH.
WHILE IT WILL OBVIOUSLY BE SNOWING FOR CATEGORICAL POPS...ACCUMS
NOT EXPECTED TO BE THRILLING AT 1-3" IN THE FAVORED AREAS FOR BOTH
OF THESE PERIODS (CHIP COUNTY IN EASTERN UPPER AND IN THE HIGHER
TERRAIN OF INTERIOR NRN LOWER AROUND GAYLORD. HIGHS AROUND 30F
WEDNESDAY WILL FALL INTO THE SINGLE DIGITS AND TEENS WEDNESDAY
NIGHT.
THURSDAY THROUGH FRIDAY...MOISTURE/COLD AIR REMAIN SUFFICIENT
THROUGH THURSDAY NIGHT FOR CONTINUED LIGHT LAKE EFFECT
ACCUMULATIONS. WNW WINDS WILL BE BACKING WITH TIME WITH LESS
MOISTURE. INVADING HIGHER PRESSURE WILL ALSO TURN THE WINDS MORE
ANTICYCLONIC THROUGH THEN WITH MAYBE A COUPLE OF INCHES IN SPOTS
IN NRN CHIP COUNTY AND FAR NW LOWER. THEN...THE NEXT CLIPPER
ARRIVES FRIDAY WITH STRONGER SW FLOW AND WARMING EXPECTED THROUGH
THE DAY FRIDAY. A WING OF WARM FRONTAL SYNOPTIC SNOWS...AND
BRIEF SW FLOW ENHANCEMENT FOR FRIDAY MORNING BEFORE THE
TEMPERATURES RISE/INVERSION HEIGHTS FALL.
FRIDAY NIGHT THROUGH EARLY NEXT WORK WEEK...LOW PRESSURE AND YET
ANOTHER COLD FRONT...SLOW MOVING...SLIDE IN ACROSS NRN MICHIGAN.
BEST LOW LEVEL CONVERGENCE AND RESULTING SNOWFALL WILL BE IN
EASTERN UPPER FRIDAY NIGHT INTO EARLY SATURDAY...BEFORE SHIFTING
SOUTH INTO NRN LOWER LATE SATURDAY AND SATURDAY NIGHT. WIND
DIRECTIONS ARE TOO UNCERTAIN AT THIS POINT...BUT DATA RIGHT NOW
SUGGESTS POOR NE FETCH ACROSS EASTERN UPPER...WITH BETTER NW FLOW
ACROSS NW LOWER FOR THE BEST ACCUMULATIONS. THE ASSOCIATED WAVE
ALOFT IS MORE DEFINED WITH EXPECTED MODEST DEEP LAYER -DIVQ. BY
SUNDAY...WINDS BACK AROUND OUT OF THE NW FOR EASTERN UPPER TO GET
BACK INTO THE LAKE EFFECT...ALONG WITH NW LOWER. SNOWS SUNDAY
NIGHT POSSIBLY ENHANCED YET AGAIN WITH NEXT IN THE SERIES OF
CLIPPERS/WAVES/SYNOPTIC SNOWFALL. LAKE EFFECT CONTINUES BEHIND
THIS CLIPPER INTO MONDAY AND TUESDAY.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z WEDNESDAY AFTERNOON)
ISSUED AT 1257 PM EST TUE JAN 15 2013
SOME MVFR CIGS DEVELOPING CLOSER TO THE LAKE MICHIGAN SHORELINE
THIS AFTERNOON WITH A FEW FLURRIES ALSO POSSIBLE. BY THIS
EVENING...DRIER AIR TEMPORARILY TAKES HOLD ONCE AGAIN AND SKIES
SHOULD SCATTER OUT. GRADIENT BEGINS TO TIGHTEN OVERNIGHT WITH
APPROACH OF COLD FRONT. DECIDED TO PUT LLWS IN THE TERMINALS AT
PLN/TVC/MBL...ALTHOUGH SURFACE WINDS MAY INCREASE ENOUGH LATER
TONIGHT TO LIMIT THIS IMPACT. STRONG COLD FRONT APPROACHES THE
AREA ON WEDNESDAY WITH THICKENING CLOUDS AND SNOWSHOWERS
DEVELOPING CLOSER TO LAKE MICHIGAN BY LATE MORNING. VERY TIGHT
PRESSURE GRADIENT AND WIND GUSTS OVER 30KTS POSSIBLE THROUGHOUT
MUCH OF THE DAY.
&&
.MARINE...
ISSUED AT 346 AM EST TUE JAN 15 2013
COMBINATION OF REMNANT OVER-WATER INSTABILITY AND TIGHTENING
PRESSURE GRADIENT AHEAD OF APPROACHING CLIPPER SYSTEM WILL RESULT
IN A QUICK INCREASE OF SOUTHWEST WINDS ACROSS NORTHERN LAKE
MICHIGAN AND THE STRAITS LATER THIS AFTERNOON...CONTINUING THROUGH
WEDNESDAY. GALES SEEM A CERTAINTY ACROSS CURRENT WATCH AREA
TONIGHT THROUGH WEDNESDAY...SO WILL UPGRADE AT THIS ISSUANCE. GALE
CONDITIONS SEEM INCREASINGLY POSSIBLE ALONG THE THE NORTHERN
PORTION OF LAKE HURON ON WEDNESDAY. STILL SOME LINGERING
UNCERTAINTY... ESPECIALLY ON TIMING. WILL ISSUE A GALE WATCH
WEDNESDAY INTO WEDNESDAY EVENING TO COVER THIS POTENTIAL.
THEREAFTER...A SEASONABLY ACTIVE PERIOD OF WEATHER IS EXPECTED
RIGHT ON INTO NEXT WEEKEND...WITH SEVERAL CLIPPER SYSTEMS CROSSING
THE WATERS... FOLLOWED BY PERIODS OF LAKE EFFECT SNOW. MORE ROUNDS
OF SMALL CRAFT ADVISORY WINDS ARE LIKELY THROUGHOUT THE LATE WEEK
AND WEEKEND.
&&
.APX WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
LH...GALE WARNING FROM 7 PM THIS EVENING TO 4 PM EST WEDNESDAY FOR
LHZ345.
GALE WATCH FROM WEDNESDAY MORNING THROUGH WEDNESDAY EVENING FOR
LHZ346-347.
LM...GALE WARNING FROM 7 PM THIS EVENING TO 4 PM EST WEDNESDAY FOR
LMZ323-341-342-344>346.
LS...NONE.
&&
$$
UPDATE...JK
SYNOPSIS...SD
SHORT TERM...MB
LONG TERM...SD
AVIATION...JK
MARINE...MB
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
1215 PM EST TUE JAN 15 2013
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 500 AM EST TUE JAN 15 2013
WV IMAGERY AND RUC ANALYSIS INDICATED A RIDGE OFF THE WEST COAST AND
A BROAD MID/UPPER LEVEL TROUGH FROM NW OF HUDSON BAY THROUGH NRN
MANITOBA/NW ONTARIO AND THE CNTRL PLAINS INTO NEW MEXICO. THE NEXT
SIGNIFICANT SHORTWAVE TROUGH WAS WELL UPSTREAM YET OVER NW CANADA. AT
THE SFC...A RIDGE EXTENDED FROM THE MID MS VALLEY INTO THE SRN GREAT
LAKES RESULTING IN WSW FLOW THROUGH THE NRN LAKES. WEBCAMS AND MODEL
FCSTS SUGGEST THAT THE HEAVER LES BANDS HAD LIFTED MAINLY NORTH OF
CALUMET INTO THE N AND W PORTIONS OF KEWEENAW COUNTY. WAA 925-700 MB
WAA HELPED SUPPORT AN ARE OF LOW/MID CLOUDS AND A FEW FLURRIES FROM NRN
MN INTO NW WI AND WRN UPPER MI.
EXPECT THAT AS WINDS CONTINUE TO BACK THIS MORNING...ANY REMAINING
LES OVER THE TIP OF THE KEWEENAW WILL LIFT OUT INTO LAKE SUPERIOR
AROUND OR SLIGHTLY AFTER 12Z. SO...THE LES WARNING WILL BE ALLOWED
TO EXPIRE. OTHERWISE...NAM/RUC 925-700 MB RH FCST SUGGESTS THAT THE
CLOUDS SHOULD THIN OUT ENOUGH BY THIS AFTERNOON FOR AT LEAST SOME
SUNSHINE. TEMPS SHOULD CLIMB TO NEAR SEASONAL AVERAGES IN TO THE LOW
TO MID 20S.
THE MODELS WERE IN GOOD AGREEMENT WITH THE POSITION AND SPEED OF THE
NW CANADA CLIPPER SHRTWV MOVING TO JUST NW OF LAKE SUPERIOR BY
12Z/WED. THE GFS...AS IS OFTEN THE CASE WAS MORE AGGRESSIVE IN
SPREADING PCPN EASTWARD THROUGH UPPER MICHIGAN LATE TONIGHT COMPARED
TO THE NAM WHICH BARELY BRINGS ANY QPF TO THE WEST BEFORE 12Z.
ALTHOUGH THE DRY AIRMASS MAY DELAY THE ARRIVAL OF LIGHT SNOW AT THE
SURFACE...THE QVECTOR CONV AHEAD OF THE SHRTWV AND UPPER LEVEL DIV
WITH THE LEFT EXIT OF THE 250-300 MB JET STILL SHOULD BE ENOUGH FOR
LIKELY POPS OVER THE FAR WEST AND CHANCE POPS OVER THE REST OF THE
WEST HALF. SNOW AMOUNTS WILL BE LIGHT AS ONLY A FEW HUNDREDTHS QPF
SUPPORTS ACCUMULATIONS OF ONLY AROUND A HALF INCH OR LESS.
.LONG TERM...(WEDNESDAY THROUGH MONDAY)
ISSUED AT 500 AM EST TUE JAN 15 2013
LONG TERM PERIOD WILL BE DOMINATED BY NORTHWEST FLOW ALOFT AS AN
UPPER LOW SPINS NEAR HUDSON BAY. THIS WILL LEAD TO A SERIES OF
CLIPPER SYSTEMS AND ASSOCIATED COLDER AIR AND LAKE EFFECT ON THE
BACK SIDE.
THE FIRST SYSTEM WILL BE MOVING THROUGH AT THE START OF THE LONG
TERM PERIOD. THIS WAVE...CURRENTLY ROUNDING THE UPPER RIDGE ALONG
THE WESTERN COAST OF NORTH AMERICA...WILL BE SLIDING ACROSS LAKE
SUPERIOR WEDNESDAY MORNING. AT THE SURFACE...A COLD FRONT WILL BE
STRETCHED FROM A LOW IN SOUTHERN HUDSON BAY AND BE SWEEPING THROUGH
THE CWA THROUGH EARLY AFTERNOON. THE WIDESPREAD MOISTURE IS ACROSS
THE NORTH HALF OF THE CWA...WHILE A THIN RIBBON OF DEEP MOISTURE
MOVES ACROSS THE CWA LATE TONIGHT AND WEDNESDAY MORNING. ALTHOUGH
IT APPEARS THE SYSTEM WILL BE FIGHTING DRY LOW LEVEL AIR TO
START...MOST OF THE CWA SHOULD SEE A PERIOD OF LIGHT SNOW OR
FLURRIES. HIGH RES MODELS REALLY PICKING UP ON THE DRIER
AIR FOR THE CENTRAL CWA AND LIMITING QPF...SO WILL CONTINUE THAT
IDEA IN THE POPS AND SNOW AMOUNTS. BEST CHANCES FOR OVER AN INCH
WILL BE OVER THE WESTERN CWA AND EAST OF MUNISING.
BEHIND THIS FRONT...A PERIOD OF LAKE EFFECT IS EXPECTED WEDNESDAY
AFTERNOON INTO THURSDAY NIGHT. COLD AIR QUICKLY SURGES IN FROM THE
NORTHWEST ON WEDNESDAY AFTERNOON AND EVENING ACROSS THE
CWA...REACHING -25C BY 12Z THURSDAY. THIS PUTS MUCH OF THE CLOUD
LAYER ABOVE THE DGZ AND SHOULD LEAD TO LOWER SNOW RATIOS. WITH THAT
BEING SAID...STILL LOOKS LIKE VERY HIGH LAKE INDUCED EQL
VALUES...AROUND 10KFT...AND CAPE VALUES AROUND 900 J/KG. THERE IS
VERY DRY AIR ABOVE THE ACTUAL INVERSION AROUND 5KFT...SO WONDERING
IF THAT COMBINED WITH THE LOWER SNOW RATIOS WILL KEEP SNOWFALL
AMOUNTS FROM BEING TOO HEAVY WEDNESDAY NIGHT INTO THURSDAY.
ONE OTHER TREND TO MENTION IS THE IDEA OF A SURFACE TROUGH
LINGERING OVER EASTERN LAKE SUPERIOR LATE WEDNESDAY NIGHT AND
POTENTIALLY DEVELOPING INTO A WEAK LOW ON THURSDAY. EVEN THE COARSE
MODELS ARE STARTING TO SHOW THIS...WHICH IF IT OCCURS...MAY HELP
FOCUS AN AREA OF CONVERGENCE IN EASTERN ALGER AND LUCE COUNTIES FOR
HEAVIER SNOW. HIGH PRESSURE RIDGE SLIDES SOUTH OF THE AREA THURSDAY
AFTERNOON INTO THURSDAY NIGHT...WHICH WILL LEAD TO BACKING WINDS
AHEAD OF THE NEXT CLIPPER THAT WILL AFFECT THE AREA ON FRIDAY. THIS
WILL LEAD TO DRIER AIR ALOFT AND WARMING H850 TEMPS...WHICH
STRENGTHENS THE INVERSION TO AROUND 6KFT WHILE ALSO PUSHING THE DGZ
BACK INTO THE CLOUD LAYER. IN ADDITION...WITH THE WINDS LIKELY
BACKING MORE TO THE WEST...EXPECT THE LAKE EFFECT TO BE CONFINED TO
THE WESTERN CWA AND RIGHT ALONG THE SHORELINE OVER THE EAST IN THE
EVENING.
LOOKING AT CIPS ANALOG GUIDANCE...THE BEST FIT FOR THIS PERIOD IS
THE DECEMBER 10-11 1980 PERIOD...WHICH CORRELATES VERY WELL IN
H850 TEMPS ALTHOUGH THE SURFACE HIGH TO THE SOUTHWEST MAY BE
SLIGHTLY CLOSER TO THE CWA. 72-HR SNOWFALL AMOUNTS DURING THAT
PERIOD WERE GENERALLY IN THE 4-12 INCH RANGE...WHICH LENDS
CONFIDENCE TO THE GOING FORECAST THOUGHTS. IN ADDITION...LOOKING AT
PROBABILITIES FROM THE TOP 15 ANALOGS THEY SHOW A SIMILAR IDEA
FOR SNOW AMOUNTS...EVEN THOUGH THE MEAN H850 TEMPS ARE A LITTLE
WARMER THAN CURRENTLY EXPECTED. WILL CONTINUE TO MENTION MODERATE
SNOW IN THE HWO...SINCE SOME LOCATIONS WILL PROBABLY NEED LAKE
EFFECT SNOW ADVISORIES...DUE TO ADDITIONAL REDUCED VISIBILITIES WITH
THE FINER SNOWFLAKES AND SOME BLOWING SNOW. IN ADDITION...LOOKING AT
COOP TEMPERATURE OBSERVATIONS DURING THAT 1980 EVENING...THE GOING
IDEA OF HIGHS OF 10-15 AND LOWS AROUND ZERO LOOKS GOOD.
MODELS CONTINUE TO HAVE SUBTLE DIFFERENCES WITH THE CLIPPER
SYSTEM...BUT THE OVERALL IDEA OF IT TRAVERSING THE CWA SEEMS
REASONABLE FOR FRIDAY. SNOW LOOKS TO ARRIVE DURING THE LATER PART
OF THURSDAY NIGHT AND INTO FRIDAY...UNDER THE STRONG H850 WAA. AT
THIS POINT...LOOKS LIKE ANOTHER DUSTING OF AROUND AN INCH OF SNOW.
THE WARMING SOUTHWEST FLOW WILL ALSO PUSH HIGHS 10-15 DEGREES
WARMER THAN THURSDAY.
AFTER THAT...CONFIDENCE QUICKLY DROPS IN THE FORECAST...AS THERE
ARE VARYING TIMES AT WHICH THE NEXT STRONGER SHORTWAVE ARRIVES.
00Z GFS IS FASTER AND ARRIVES EARLY SATURDAY...WHILE THE 00Z
ECMWF/GEM HAVE IT ARRIVING SATURDAY AFTERNOON. FOR THIS TIME OF THE
YEAR...THESE DIFFERENCES MAKE A HUGE DIFFERENCES FOR THE FORECAST
DUE TO WIND FIELDS...H850 TEMPS...AND POTENTIAL FOR LAKE EFFECT.
WILL JUST GO WITH A GENERAL CHANCE POPS FOR THE ENTIRE AREA...WITH
THE HIGHEST VALUES NEAR LAKE SUPERIOR.
ONCE THIS WAVE DEPARTS...LOOKS TO BE ANOTHER PERIOD OF MULTI-BAND
LAKE EFFECT FOR THE NORTHWEST WIND LAKE EFFECT AREAS SUNDAY INTO
MONDAY. AFTER BECOMING DISRUPTED SOME WITH THE LAST SHORTWAVE...THE
UPPER TROUGH WILL AGAIN REESTABLISH ITSELF OVER THE GREAT LAKES
THROUGH THE FIRST PART OF NEXT WEEK. H850 TEMPS WILL AGAIN BE AROUND
-25C AND LEAD TO PERIODS OF MODERATE LAKE EFFECT SNOW. WILL BUMP
POPS UP BASED OFF LOCAL LAKE EFFECT CLIMATOLOGY GRIDS TO HIGH
CHANCE OR LOW LIKELY VALUES FOR NORTHWEST WIND LOCATIONS.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z WEDNESDAY AFTERNOON)
ISSUED AT 1214 PM EST TUE JAN 15 2013
VFR CONDITIONS WILL CONTINUE THROUGH THE OVERNIGHT HOURS AT ALL 3
SITES BEFORE AN ALBERTA CLIPPER COMES IN AND GIVES SOME LIGHT SNOW
TO THE AREA. TOOK CONDITIONS DOWN TO IFR AT CMX AND IWD FOR THIS AND
MVFR AT SAW BY WED MORNING. ALTHOUGH WINDS WILL BE MAINLY
DECOUPLED...EXPECT GUSTY CONDITIONS AT IWD MAY LIMIT LLWS POTENTIAL.
DID PUT IN SOME LLWS TONIGHT AT SAW BEFORE GUSTY CONDITIONS DEVELOP
LATE TONIGHT. SW WINDS AT CMX ARE NOT GUSTY IN GENERAL DUE TO
TERRAIN.
&&
.MARINE...(FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 500 AM EST TUE JAN 15 2013
SOUTHWEST WINDS WILL INCREASE THIS AFTERNOON AND TONIGHT AHEAD OF
AN APPROACHING COLD FRONT. THIS WILL PRODUCE GALES TO 35-40KTS AND
WILL CONTINUE THE GALE WARNING FOR TONIGHT INTO WEDNESDAY. WINDS
WILL SHIFT TO THE WEST AND THEN NORTHWEST AND GUST TO 40KTS DURING
THE DAY WEDNESDAY BEHIND THE FRONT. NORTHWEST WINDS OF 15-30KTS
WILL CONTINUE WEDNESDAY NIGHT INTO THURSDAY...WITH OCCASIONAL GALE
FORCE GUSTS TO 35KTS. A SERIES OF CLIPPER SYSTEMS ARE EXPECTED TO
MOVE THROUGH ON FRIDAY AND AGAIN ON SATURDAY. THIS WILL DISRUPT THE
WINDS SOME DURING THOSE PERIODS...WITH NORTH-NORTHWEST WINDS TO
30KTS AGAIN EXPECTED SATURDAY NIGHT.
FINALLY...HEAVY FREEZING SPRAY IS EXPECTED WEDNESDAY NIGHT INTO
THURSDAY EVENING OVER MUCH OF LAKE SUPERIOR.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
GALE WARNING FROM 7 PM THIS EVENING TO 7 PM EST WEDNESDAY FOR
LSZ264>267.
GALE WARNING FROM 7 PM EST /6 PM CST/ THIS EVENING TO 1 PM EST
/NOON CST/ WEDNESDAY FOR LSZ162-263.
GALE WARNING FROM 1 AM TO 7 PM EST WEDNESDAY FOR LSZ244-245-
249>251.
GALE WARNING FROM 1 PM TO 7 PM EST WEDNESDAY FOR LSZ248.
GALE WARNING FROM 1 AM EST /MIDNIGHT CST/ TO 1 PM EST /NOON CST/
WEDNESDAY FOR LSZ240>243.
LAKE MICHIGAN...
GALE WARNING FROM 4 AM TO 1 PM EST WEDNESDAY FOR LMZ221-248-250.
&&
$$
SHORT TERM...JLB
LONG TERM...SRF
AVIATION...07
MARINE...SRF
AREA FORECAST DISCUSSION
NWS BISMARCK ND
344 PM CST TUE JAN 15 2013
.SHORT TERM...TONIGHT THROUGH WEDNESDAY NIGHT...
THE MAIN HIGHLIGHT FOR THE SHORT TERM IS THE LATEST ROUND OF LIGHT
SNOW AND DIAGNOSING THE SEVERITY OF BLOWING SNOW.
LIGHT SNOW CONTINUES TO SPREAD SOUTHEAST ACROSS PORTIONS OF WESTERN
AND CENTRAL NORTH DAKOTA THIS AFTERNOON. LATEST OBS HAVE SHOWN
REDUCED VISIBILITY OF AROUND 1 MILE IN LIGHT SNOW...WITH INCREASING
WESTERLY WINDS ACROSS THE WEST. EVEN THOUGH REDUCED VISIBILITIES
HAVE BEEN OBSERVED ACROSS PORTIONS OF THE WEST...THE MAIN AREA OF
LIGHT SNOW WILL NOT COINCIDE WITH THE STRONGEST FORECAST WINDS
THROUGH EARLY TONIGHT. IN ADDITION...MILD TEMPERATURES AND SOME
DRIZZLE THAT OCCURRED LATE THIS MORNING...WILL HELP LIMIT THE
SEVERITY OF BLOWING SNOW...KEEPING VISIBILITIES ABOVE ADVISORY
CRITERIA. WILL CONTINUE THE TRAIN OF THOUGHT FROM PREVIOUS
SHIFTS...SINCE CONDITIONS DO NOT WARRANT AN ISSUANCE OF AN ADVISORY.
THE 12Z NAM AND LATEST RAP RUNS HAVE INITIALIZED WELL WHEN COMPARED
TO CONDITIONS AT 20Z. THEY BOTH CAPTURE THE TIMING OF THE CURRENT
ONSLAUGHT OF LIGHT SNOW OVER WESTERN AND CENTRAL NORTH DAKOTA. HAVE
OPTED TO USE A BLEND OF BOTH FOR POPS AND QPF. IN REGARDS TO
PRECIPITATION TYPE...MODEL SOUNDINGS SHOW A SHALLOW WARM LAYER ALOFT
LATER TONIGHT WHICH WILL SUPPORT THE POSSIBILITY OF SLEET AT TIMES ACROSS
THE WEST AND PORTIONS OF CENTRAL NORTH DAKOTA.
ANOTHER IMPULSE WILL ENTER NORTH CENTRAL NORTH DAKOTA MID MORNING
TOMORROW ALONG THE BAROCLINIC ZONE THAT HAS SET UP FROM THE
NORTHWEST TO SOUTHEAST TODAY...GENERATING ANOTHER ROUND OF
PRECIPITATION FOR PORTIONS OF CENTRAL NORTH DAKOTA TOMORROW.
PRECIPITATION TYPE WILL BE IN THE FORM OF LIGHT SNOW AS TEMPERATURES
WILL BE BELOW FREEZING. ONLY LIGHT ACCUMULATIONS UNDER AN INCH ARE
EXPECTED FROM ALONG THE INTERNATIONAL BORDER SOUTHEAST THROUGH THE
JAMES RIVER VALLEY.
.LONG TERM...THURSDAY THROUGH TUESDAY...
THE HIGHLIGHT OF THE EXTENDED FORECAST CONTINUES TO BE A POTENTIAL
ARCTIC OUTBREAK THIS WEEKEND INTO NEXT WEEK.
PRIOR THE POTENTIAL ARCTIC SURGE...WESTERN AND CENTRAL NORTH DAKOTA
WILL STRADDLE THE LOW LEVEL BAROCLINIC ZONE UNDER THE POLAR JET AXIS
ALOFT. THIS IS EXPECTED TO RESULT IN A LARGE TEMPERATURE
GRADIENT...ESPECIALLY ON THURSDAY WITH HIGHS IN THE 30S SOUTHWEST TO
THE SINGLE DIGITS ACROSS THE TURTLE MOUNTAINS. THERE IS A CHANCE OF
LIGHT SNOW...WITH TOTAL ACCUMULATIONS OF ONE TO TWO INCHES THURSDAY
NIGHT INTO FRIDAY FOR THE NORTH CENTRAL AND JAMES RIVER VALLEY AS
MULTIPLE IMPULSES EMBEDDED IN FAST...CYCLONIC FLOW ALOFT INTERACT
WITH THE AFOREMENTIONED LOW LEVEL BAROCLINICITY.
THEREAFTER...A VERY STRONG COLD FRONT IS FORECAST TO PROPAGATE
THROUGH WESTERN AND CENTRAL NORTH DAKOTA ON SATURDAY...MARKING THE
BEGINNING OF A POTENTIAL ARCTIC OUTBREAK CONTINUING POSSIBLY INTO
TUESDAY. THE OVERALL 12 UTC GUIDANCE SUITE IS IN GOOD AGREEMENT IN
THE DEVELOPMENT OF A HIGH AMPLITUDE UPPER LEVEL RIDGE ALONG THE
PACIFIC COAST AND INTO THE ARCTIC THROUGH THE WEEKEND AND INTO NEXT
WEEK...WHICH SHOULD ALLOW VERY COLD ARCTIC AIR TO BE TRANSPORTED
SOUTH UNDER DEEP CYCLONIC FLOW ALOFT. THE COLDEST TIMEFRAME APPEARS
TO BE SUNDAY THROUGH MONDAY NIGHT AS A NEAR 1050 MB SURFACE HIGH ON
THE DETERMINISTIC MODELS IMPACTS THE AREA. GIVEN GOOD
AGREEMENT...WILL UTILIZE A BLEND OF THE GUIDANCE...WHICH RESULTS IN
WIDESPREAD LOWS SUNDAY AND MONDAY NIGHTS OF -15 TO -25 WITH SUB-ZERO
DAYTIME HIGHS ON MONDAY. WIND CHILL TEMPERATURES COLDER THAN -40 ARE
NOT OUT OF THE QUESTION. SHOULD TRENDS CONTINUE...A WIND CHILL WATCH
MAY BE NECESSARY LATER THIS WEEK.
&&
.AVIATION...
AS OF 2130 UTC...A WARM FRONT HAD ALREADY PASSED THROUGH KISN AND
KDIK...AND WAS APPROACHING THE KMOT AND KBIS TERMINALS. A BRIEF
PERIOD OF FREEZING DRIZZLE HAS BEEN OBSERVED IN THE IMMEDIATE VICINITY
OF THE FRONT THIS AFTERNOON...WITH A BAND OF LIGHT TO MODERATE
SNOWFALL IN TRAIL. IFR/MVFR CONDITIONS IN STRATUS AND SNOW ARE
EXPECTED AT ALL TERMINALS THROUGH THE AFTERNOON AND EVENING.
WESTERLY WIND GUSTS OF 25-35 KTS BEHIND THE FRONT MAY CREATE SOME
DRIFTING SNOW. HOWEVER...ABOVE FREEZING TEMPERATURES BEHIND THE
FRONT WILL CRUST THE SNOW AND LIMIT ITS OVERALL LOFTING.
&&
.BIS WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...LTH
LONG TERM/AVIATION...PJA
AREA FORECAST DISCUSSION
NWS BISMARCK ND
110 PM CST TUE JAN 15 2013
.DISCUSSION...
LIGHT SNOW HAS BEGUN TO SPREAD EAST OUT OF EASTERN MONTANA INTO
PORTIONS OF THE WEST EARLY THIS AFTERNOON. FOR A BRIEF
PERIOD...THERE WERE SOME REPORTS OF LIGHT FREEZING DRIZZLE OUT
AHEAD OF THE MAIN AREA OF PRECIPITATION. HOWEVER...AS THE
ENVIRONMENT HAS BEGUN TO SATURATE THE LIGHT FREEZING DRIZZLE HAS
QUICKLY CHANGED OVER TO LIGHT SNOW. AS A RESULT...DECIDED NOT
MENTION FREEZING DRIZZLE IN GRIDS.
LATEST RUNS OF THE RAP AND NAM HAVE SLOWED DOWN AND LESSENED THE
INTENSITY OF THE LIGHT SNOW ACROSS THE AREA...WHICH AGREES WITH
CURRENT TRENDS AND OBS. HAVE MADE ADJUSTMENTS TO POPS/QPF/WX GRIDS
TO REFLECT THIS. OTHERWISE...MADE COSMETIC ADJUSTMENTS TO ALL
OTHER GRIDS.
&&
.AVIATION...
AS OF 19 UTC...IFR/MVFR STRATUS WAS IMPACTING
KISN...KMOT...KDIK AND KBIS AND WILL REMAIN IN PLACE THROUGH 03-06
UTC TONIGHT. THIS DECK IS EXPECTED TO REACH KJMS BETWEEN 19-20 UTC
AND HOLD THROUGH THE 12 UTC TAF CYCLE. A WARM FRONT IS ALSO FORECAST
TO MOVE THROUGH THE AREA THIS AFTERNOON...WITH WITH AREAS OF LIGHT
SNOW ACCOMPANYING IT...WITH PATCHY FREEZING DRIZZLE IN THE IMMEDIATE
VICINITY OF THE FRONT. WESTERLY WINDS GUSTING BETWEEN 25-35 KTS
BEHIND THE FRONT WILL CREATE AREAS OF BLOWING SNOW.
&&
.BIS WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
DISCUSSION...HUBER
AVIATION...AYD
AREA FORECAST DISCUSSION...UPDATED
NWS GRAND FORKS ND
1037 AM CST TUE JAN 15 2013
.DISCUSSION...CLIPPER SYSTEM WILL CONTINUE TO APPROACH THE REGION
TODAY WITH THE MAIN IMPACTS HOLDING OFF UNTIL THE OVERNIGHT HOURS.
A BAND OF WARM AIR ADVECTION SNOWFALL WILL MOVE INTO THE NE FA BY
LATE AFTERNOON...AND THROUGH THE REGION THIS EVENING. SNOWFALL
AMOUNTS LIKELY LESS THAN AN INCH. A BIT MORE SNOWFALL...AN INCH
OR TWO...POSSIBLE ACROSS THE NE FA CLOSER TO THE MAIN UPPER WAVE
AND STRONG UPPER JET. THIS IS ALL IN LINE WITH THE PREVIOUS
FORECAST...BUT DID INCREASE POPS TO CATEGORICAL ALONG AND NORTH OF
A COOPERSTOWN TO PARK RAPIDS LINE GIVEN UPSTREAM RADAR IMAGERY AND
INCOMING 12Z MODELS. 925MB TEMPERATURES WILL RISE TO NEAR FREEZING
ALONG AND WEST OF THE VALLEY AHEAD OF THE COLD FRONT...WITH LOW
LEVEL WESTERLY FLOW. FEEL CONFIDENT THIS WILL LEAD TO SFC
TEMPERATURES 31F-34F ACROSS THIS AREA...AND WILL ADJUST HOURLY
TEMPS TONIGHT (USING THE RAP AS A GUIDE). THIS SYSTEM IS A BIT
SLOWER...WITH STRONGEST 925MB COLD AIR ADVECTION HOLDING OFF UNTIL
AFTER 06Z ACROSS THE NORTHERN FA. A BRIEF PERIOD OF GUSTY WINDS
(30MPH-40MPH) LIKELY...BUT WILL BE BRIEF. BLOWING SNOW POTENTIAL
IS LOW GIVEN MINIMAL ADDITIONAL SNOWFALL AND TEMPERATURES NEAR
FREEZING BEFORE STRONGEST WINDS (TOP LAYER OF SNOWPACK WILL BE TOO
DENSE TO BLOW AROUND). SOUTHERLY/WESTERLY WINDS AHEAD OF THE COLD
FRONT WILL BE BREEZY...AND COULD LEAD TO A BIT OF DRIFTING SNOW
WHERE THERE IS LOOSE SNOW COVER.
&&
.AVIATION...
EXPECT PERIODIC VFR CEILINGS WITH SOME BREAKS IN CLOUD COVER
THROUGH THE DAY. LOW VFR/MVFR CEILINGS POSSIBLE LATER THIS EVENING
AND OVERNIGHT AS NEXT LOW PRESSURE SYSTEM MOVES ACROSS THE REGION.
SOME LIGHT SNOW IS ALSO POSSIBLE...LASTING A FEW HOURS WITH MVFR
VSBYS IN THE 3-5 SM RANGE. WINDS WILL BE SOUTHERLY AND INCREASE TO
15 TO 20 KTS THIS AFTN IN THE RRV AND DVL REGION AND THEN TURN
WEST TO NORTHWEST WITH A PERIOD OF GUSTS TO 30 KTS AROUND 06Z.
BEMIDJI AREA TO HAVE SOUTHERLY WINDS 10 TO 15 KTS TODAY THEN TURN
NORTHWEST AFTER 06Z WED. &&
.PREV DISCUSSION... /ISSUED 348 AM CST TUE JAN 15 2013/
SHORT TERM...
SATELLITE EARLY THIS MORNING SHOWS AREAS OF CLOUDS....INTERSPERSED
WITH CLEAR HOLES. THIS CREATING THE USUAL TEMP DIFFERENCES WITH
ZERO TO 5 BELOW IN CLEAR AREAS AND 5 TO 10 ABOVE IN CLOUD AREAS.
EXPECT THIS HODGEPODGE OF CLOUDS/CLEAR WILL CONTINUE THIS MORNING
OVER THE MINNESOTA FCST AREA WHILE MORE GENERAL MID AND HIGH LEVEL
MOISTURE MOVES IN FROM THE WEST INTO ERN ND AHEAD OF THE NEXT
SHORT WAVE. WINDS WILL INCREASE THIS AFTN AND BECOME A BIT BREEZY
IN THE RED RIVER VALLEY AS PRESSURE FALLS AHEAD OF THE NEXT LOW
WHICH WILL DROP SOUTHEAST THROUGH SOUTHERN MANITOBA INTO THE LAKE
OF THE WOODS REGION TONIGHT.
LOOK FOR A BAND OF LIGHT SNOW TO ADVANCE EAST INTO THE DVL REGION
SOUTH OF THE SFC LOW AND AHEAD OF THE SURFACE TROUGH VERY LATE
THIS AFTN AND THEN SPREAD EAST THIS EVENING...ENDING IN THE FAR
EAST OVERNIGHT. WITH SFC LOW TO OUR NORTHEAST AND LACK OF ANY VERY
STRONG VORT...THESE EVENTS OFTEN PRODUCE ONLY MINOR ACCUMS (LESS
THAN AN INCH). EXCEPTION WILL BE LAKE OF THE WOODS WHERE AN INCH
OR TWO WILL OCCUR. BRIEF PERIOD OF NORTHWEST WINDS BEHIND THE LOW
AND TROUGH WITH SUSTAINED VALUES 15 TO 22 KTS AND WIND GUSTS TO NR
30 KTS...ESP IN THE DEVILS LAKE BASIN INTO THE SHEYENNE RIVER
BASIN. WITH SUCH VERY MINIMAL SNOW WITH SYSTEM ANY BLOWING SNOW
ISSUES WILL BE BRIEF AND SHOULDNT BE A HUGE ISSUE. WILL CONTINUE
WITH BLSN MENTION BUT NO ADVISORY FORSEEN.
TEMPS WILL BE AN ISSUE....AS TEMPS SLOWLY RISE TODAY...THEN LOOK
FOR A QUICK RISE WELL INTO THE 20S TO AROUND 30 IN ERN ND AND
PARTS OF THE RED RIVER VALLEY JUST BEHIND SFC TROUGH AS WINDS GO
MORE WEST TO NORTHWEST 04Z-08Z PERIOD. THEREAFTER COLDER AIR WILL
DROP SOUTH AND TEMPS WILL START TO FALL. BUT ALL MODELS SHOW VERY
TIGHT THERMAL GRADIENT FROM MINOT TO COOPERSTOWN TO NEAR FARGO TO
FERGUS FALLS LATE TONIGHT INTO WEDNESDAY. THIS BOUNDARY WILL BE
THE FOCUS FOR A SECOND WEAK LOW WHICH WILL PASS ALONG THE BOUNDARY
WEDNESDAY GIVING ANOTHER SHOT OF LIGHT SNOW. AGREED WITH WFO BIS
TO GO LIKELY POPS FOR A PERIOD WEDNESDAY ALONG THIS THERMAL
GRADIENT FOR UP TO HALF INCH OF SNOW. AFTER THIS LOW
PASSES...COLDER AIR WILL DROP SOUTH THRU ALL THE FCST AREA WED
NIGHT AS HIGH MOVES IN. THEN NEXT SHORT WAVE AND SFC LOW TO
APPROACH LATER THU INTO THURS NIGHT CAUSING THE THERMAL BOUNDARY
TO RETURN NORTH A BIT.
LONG TERM (FRI-MON)...
MODELS IN FAIR AGREEMENT WITH THE EXTENDED TIME FRAME AS 500MB NW
FLOW GIVES WAY TO MORE DIRECTLY NORTH FLOW AS RIDGE AXIS ACROSS THE
NORTH AMERICAN PACIFIC COAST AMPLIFIES NORTH AND PULLS DOWN PRISTINE
ARCTIC AIRMASS BY THE END OF THE PERIOD. FRIDAY WILL BE THE WARMEST
DAY AS WESTERLY SFC WINDS DEVELOP IN THE WAKE OF SFC LOW PASSAGE
ALONG THE INTERNATIONAL BORDER. SCHC OF -SN ACROSS THE N RRV AND
INTO THE BJI AND BDE AREAS FRI. FIRST IN A SERIES OF COLD FRONTS
SURGES SOUTH SAT WITH ANOTHER -SN CHC THEN AGAIN ON SUNDAY ACROSS
THE SOUTH AS THE BRUNT OF THE ARCTIC AIRMASS MAKES ITS WAY INTO THE
REGION SUN PM. TEMPS WELL BELOW NORMAL BY MONDAY WITH HIGHS IN THE 5
TO 15 BELOW RANGE EXPECTED.
&&
.FGF WATCHES/WARNINGS/ADVISORIES...
ND...NONE.
MN...NONE.
&&
$$
TG
AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY
NWS RAPID CITY SD
250 PM MST TUE JAN 15 2013
.DISCUSSION...VIGOROUS DEEP LAYER WAA AND HEIGHT RISES ONGOING
ACROSS THE FA...WITH UPSLOPE ENHANCEMENT BEGINING TO REV UP. POTENT
UPPER LEVEL RIDGING AND ASSOCIATED WAA WILL CONTINUE THROUGH MOST OF
THE PERIOD...ALTHOUGH A PASSING NORTHERN STREAM DISTURBANCE WILL
OFFER A SHORT LULL IN WAA ACROSS THE NORTHERN HALF OF THE FA
WED...WITH WAA BEGINNING TO SPREAD OVER THE REGION AGAIN WED NIGHT
THUR AS THE REGION REMAINS ON THE WARM SIDE OF A VERY STRONG
BAROCLINIC ZONE. NEAR SATURATED WAA WILL CONTINUE THROUGH THIS
EVENING...BEFORE DRIER AIR ADVECTS INTO THE FA...SUPPORTING AN END
TO UPGLIDE/UPSLOPE INDUCED SNOW.
STRONG LOW CENTERED OMEGA MAX IS OFFERING STAUNCH LOW LEVEL LIFT IN
A NEAR SATURATED BL...WITH A RISING FROUDE NUMBER IN THE NORTHERN
BLACK HILLS. RAP POINT SOUNDINGS IN FAR WESTERN LAWRENCE COUNTY
INDICATE A DEEPLY SATURATED BL. HOWEVER...WAA IS SHUNTING THE LAYER
OF MAXIMUM OMEGA OUT OF THE DGZ INTO INCREASINGLY WARMER AIR. THIS
HAS ALLOWED THE PRODUCTION OF FREEZING DRIZZLE AT TIMES...WHICH IS
EXPECTED TO MIX WITH UPSLOPE SNOWS THROUGH THE AFTERNOON/EVENING..AS
LL PROFILES WARM AND MID LEVEL DRYING COMMENCES. SNOW MAY MIX WITH
OR CHANGE OVER TO ALL FREEZING DRIZZLE AT TIMES...ESP WITH
OSCILLATING INTENSITY OF UPSLOPE ENHANCEMENT AND ANY SEEDER-FEEDER
PROCESS. STILL EXPECT ANOTHER 1-3 INCHES THROUGH THE EVENING IN TH
ADV...WITH LOCALLY HIGHER AMOUNTS WHERE SNOW PERSISTS...ALTHOUGH ZL
MIXING MAY LIMIT SNOWS SIG IN SOME AREAS. WILL KEEP THE ADV GOING
THROUGH THE CURRENT EXPIRATION TIME.
BREEZY CONDITIONS CAN BE EXPECTED THROUGH WED GIVEN THE LL BAROCLINIC
ZONE IN PLACE ACROSS THE REGION/EXPECTED PRESSURE FALLS...ALTHOUGH
WAA WILL OFFSET THE INTENSITY OF WINDS TONIGHT. A LITTLE BETTER
MIXING AND WEAK CAA ACROSS THE NORTH WILL ALLOW FOR BREEZY
CONDITIONS OVER THE SD PLAINS ON WED.
DRIER AIR WILL WORK INTO THE AREA...WITH SIG AMOUNTS OF HIGH CLOUDS
EXPECTED TO REMAIN GIVEN THE LOCATION OF THE UPPER JET. IN
ADDITION...A WEAK SECONDARY COLD FRONT/TROUGH WILL ADVECT THROUGH
THE AREA...SUPPORTING SOME MID CLOUD ACROSS THE NORTH...WITH
DECREASING CLOUDS THROUGH THE WED PERIOD. ALTHOUGH VERY WARM
PROFILES ARE PROGGED JUST ABOVE THE SFC...HIGH CLOUD COVER MAY LIMIT
T RISES TO A POINT WED...ESP AWAY FROM DOWNSLOPE AREAS AND WHERE A
DEEPER SNOW PACK IS IN PLACE. LOWS WILL REMAIN TRICKY...ESP WED
NIGHT WHEN WAA AND A LINGERING PRESSURE GRADIENT IN PLACE IS
ALLOWING SOME MODEL PROGS TO FORECAST MUCH WARMER TEMPS THAN SOME
OTHER SOLUTIONS. HAVE SIDED SOME TOWARD THIS WARMER SOLUTION WHICH
HAS BEEN EVIDENT THE LAST SEVERAL RUNS...ALTHOUGH QUESTIONS ON SNOW
COVER AND DECOUPLING REMAIN. HAVE INCORPORATED SOME DOWNSLOPE
EFFECTS ON THUR/S HIGHS WHICH WILL AGAIN REMAIN TRICKY.
EXTENDED...FAST NORTHWEST FLOW WILL CONTINUE OVER THE NORTHERN
PLAINS THROUGH EARLY NEXT WEEK. THE FORECAST AREA WILL REMAIN UNDER
THE INFLUENCE OF THE WESTERN RIDGE FOR ONE MORE DAY ON FRIDAY...WITH
DRY CONDITIONS AND MILD TEMPERATURES. CHANGES WILL COME THIS WEEKEND
AS A COMPACT SHORTWAVE DIVES THROUGH NORTHERN MINNESOTA...DRAGGING A
STRONG COLD FRONT ACROSS THE DAKOTAS FRIDAY NIGHT INTO SATURDAY.
TEMPERATURES WILL COOL DRAMATICALLY BY SUNDAY AND MONDAY AS ARCTIC
AIR SETTLES ACROSS THE NORTHERN PLAINS. ANOTHER WEAKER SHORTWAVE
WILL CROSS THE DAKOTAS ON SUNDAY...GIVING THE AREA A CHANCE FOR
LIGHT SNOW THROUGH SUNDAY NIGHT.
&&
.AVIATION...18Z TAF UPDATE
IFR/LIFR CIGS/VIS IN SNOW WILL CONTINUE OVER NERN WY INTO THE BLKHLS
AND NWRN SD THROUGH THIS EVENING. SOME FREEZING DRIZZLE WILL BE
POSSIBLE OVER THE NORTHERN BLACK HILLS. ACROSS THE SD PLAINS...MVFR
CIGS ARE ALSO EXPECTED TO CONTINUE THROUGH THIS EVENING...WITH AREAS
OF IFR VIS EXPECTED IN AREAS OF SNOW. CONDITIONS WILL IMPROVE LATE
TONIGHT FROM WEST TO EAST AS SNOW ENDS.
&&
.UNR WATCHES/WARNINGS/ADVISORIES...
SD...WINTER WEATHER ADVISORY UNTIL 11 PM MST THIS EVENING FOR CENTRAL
BLACK HILLS-NORTHERN BLACK HILLS.
WY...WINTER WEATHER ADVISORY UNTIL 11 PM MST THIS EVENING FOR WYOMING
BLACK HILLS.
&&
$$
SHORT TERM...JC
EXTENDED...15
AVIATION...15
AREA FORECAST DISCUSSION...UPDATED
NWS FORT WORTH TX
1154 AM CST TUE JAN 15 2013
.UPDATE...
DRIZZLE CONTINUES ALONG AN AXIS FROM BOSQUE COUNTY TO ELLIS AND
NAVARRO COUNTIES...EXTENDING TO OUR EASTERN ZONES. TEMPERATURES
HAVE BEEN VERY SLOW TO WARM WHERE DRIZZLE IS OCCURRING AND TEMPS
IN THIS REGION REMAIN AROUND 32 DEGREES. HAVE EXTENDED THE
ADVISORY UNTIL 2 PM FOR THESE LOCATIONS AND WILL LET THE REST OF
THE ADVISORY EXPIRE. INCLUDED DALLAS COUNTY IN THE EXTENSION
BECAUSE LANCASTER AND MESQUITE ARE AT 32 DEGREES WITH FREEZING
DRIZZLE...SO THE MAIN IMPACTS WILL BE CONFINED TO THE EXTREME
SOUTHEASTERN PORTIONS OF DALLAS COUNTY. TEMPERATURES SHOULD BE
ABOVE FREEZING BETWEEN 1 AND 2 PM.
HAMPSHIRE
&&
.AVIATION...
CIGS ACROSS THE METROPLEX TAF SITES ARE GENERALLY VFR OR ARE IN THE
PROCESS OF LIFTING TO VFR SHORTLY. MAIN AREA OF DRIZZLE AND
FREEZING DRIZZLE IS TO THE SOUTH OF TAF SITES AND SHOULD REMAIN
THERE. THEREFORE NOT EXPECTING ANY ADDITIONAL WINTER ISSUES AT TAF
SITES...AND A DRY FORECAST WITH NO CONCERNS IS EXPECTED TONIGHT
AND TOMORROW. CIGS WILL CONTINUE TO LIFT DURING THE AFTERNOON AND
OVERNIGHT HOURS AS DRIER AIR MOVES INTO THE AREA. WINDS WILL BE
NORTH NEAR 10KT BECOMING WEST TONIGHT.
FOR WACO...IFR CIGS WILL GRADUALLY LIFT DURING THE AFTERNOON HOURS
TO MVFR...AND VFR IS EXPECTED BY SUNSET. LIGHT DRIZZLE OR MIST IS
OCCURRING NOW...BUT SHOULD TAPER OFF BY MID AFTERNOON. NORTH WINDS
AT 10 KT WILL BECOME WEST BY MORNING.
TR.92
&&
.PREV UPDATE...
.UPDATE...
LATEST ISENTROPIC PLOTS FROM THE RAP CONTINUE TO SHOW WEAK UPGLIDE
THROUGH 700 MB PERSISTING FOR MOST OF THE MORNING AND EARLY
AFTERNOON. FORECAST SOUNDINGS DEPICT DRYING IN THE UPPER LEVELS OF
THE ATMOSPHERE AND THIS WEAK LIFT WOULD BE SUPPORTIVE OF DRIZZLE.
STARTING TO SEE LIGHT RETURNS WEST OF INTERSTATE 35...BUT NOTHING
HAS BEEN REPORTED YET AT ANY OF THE AREA OBSERVATION SITES. NOT
MUCH PRECIP FELL IN THESE LOCATIONS AND AS THIS WEAK LIFT IN THE
LOWEST ATMOSPHERE SHIFTS EAST...DRIZZLE IS LIKELY TO FORM ACROSS
THE AREA WHICH PICKED UP OVERNIGHT PRECIP. LATEST RAP ALSO KEEPS
TEMPERATURES BELOW FREEZING UNTIL NOON OR 1 PM...AND WE EXTENDED
THE ADVISORY UNTIL NOON. THE FREEZING DRIZZLE WOULD BE PROBLEMATIC
AS THIS WOULD FALL ON TOP OF THE SLEET/SNOW AND MAKE THE AREA
BRIDGES AND OVERPASSES EVEN MORE HAZARDOUS.
HAMPSHIRE
&&
.PREV DISCUSSION... /ISSUED 448 AM CST TUE JAN 15 2013/
SHORT TERM WINTER WEATHER CONCERNS...
ONCE AGAIN WE HAVE A THREAT FOR WINTRY PRECIPITATION TO DEVELOP
OVER PORTIONS OF NORTH AND CENTRAL TX EARLY THIS MORNING. THE LONG
WAVE TROUGH OVER THE WESTERN CONUS HAS BECOME POSITIVELY TILTED
ALREADY THIS MORNING AND ITS AXIS NOW ORIENTED FROM NORTHERN
MINNESOTA SOUTHWEST TO THE SOUTHERN NEW MEXICO AND ARIZONA BORDER.
THE TROUGH WAS SHOWING SIGNS OF MOVING EAST ALREADY EARLY THIS
MORNING. THIS EASTWARD MOVEMENT...COMBINED WITH A COMPACT
SHORTWAVE TROUGH EMBEDDED IN THE SOUTHWEST FLOW ALOFT OVER THE
SOUTHERN HIGH PLAINS IS LIKELY PROVIDING THE LARGE SCALE FORCING
FOR ASCENT EVIDENT ON WATER VAPOR IMAGERY OVER NORTH TX AT THIS
TIME. EVIDENCE OF LARGE SCALE FORCING FOR ASCENT WAS SHOWING UP IN
IR SATELLITE IMAGERY AND VWP PROFILES EARLY THIS MORNING AS WELL.
IR SATELLITE IMAGERY INDICATES COOLING CLOUD TOPS OVER MUCH OF
NORTH AND CENTRAL TX WHILE REGIONAL RADAR VWP SHOWS LOW LEVEL FLOW
VEERING STRONGLY WITH HEIGHT...A SIGN OF WARM AIR ADVECTION AND
ISENTROPIC LIFT. ALL OF THIS IS EVIDENCE THAT WE WILL LIKELY SEE
RADAR RETURNS BLOSSOM AROUND NORTH AND CENTRAL TX THIS MORNING AS
PERSISTENT ASCENT EVENTUALLY RESULTS IN SCATTERED PRECIPITATION
DEVELOP OVER THE REGION.
CONFIDENCE IS FAIRLY HIGH THAT PRECIPITATION WILL DEVELOP OVER
MOST AREAS ALONG AND SOUTHEAST OF A BONHAM TO FORT WORTH TO
LAMPASAS LINE EARLY THIS MORNING. AS A RESULT WENT AHEAD AND
BUMPED UP POPS INTO THE 30 TO 50 PERCENT RANGE FOR THESE LOCATIONS
THROUGH THE MORNING HOURS. CONFIDENCE WAVERS WHEN DETERMINING WHAT
FORM THIS PRECIPITATION WILL FALL AS IT DEVELOPS AND MOVES
NORTHEAST OVER THESE LOCATIONS. THERE ARE SEVERAL FACTORS TO
CONSIDER...AND ILL DETAIL SOME OF THOSE BELOW.
THE EASIEST THING TO NOTICE IS THAT SURFACE TEMPERATURES ARE A
GOOD 5 DEGREES WARMER THAN EXPECTED TO START OFF THE FORECAST
TODAY. THIS IS ONE GOOD CONSEQUENCE OF THE MODELS UNDERESTIMATING
THE STRENGTH OF LARGE SCALE FORCING FOR ASCENT OVER THE
REGION...CLOUDS BUILT IN EARLIER THAN EXPECTED WHICH PREVENTED
TEMPERATURES FROM FALLING BELOW FREEZING SOUTH OF INTERSTATE
20...AT LEAST AS OF 4 AM CST. THIS AT LEAST ALLEVIATES CONCERNS
FOR FREEZING RAIN OVER THE WACO/KILLEEN/TEMPLE AREAS EARLY THIS
MORNING.
FURTHER NORTH...PRECIPITATION IS EXPECTED TO DEVELOP AROUND OR
AFTER 5 AM CST NEAR THE DFW METROPLEX...WHILE 4 AM SURFACE
OBSERVATIONS INDICATED THAT THE WET BULB ZERO LINE WAS LOCATED AS
FAR SOUTH AS CLEBURNE AND WAXAHACHIE. 05Z AMDAR AIRCRAFT SOUNDINGS
INDICATED THAT THE THERMAL PROFILE OVER THE METROPLEX WAS MOSTLY
SUPPORTIVE OF SNOW...WITH A SURFACE TO 700 MB ISOTHERMAL LAYER
HUGGING THE 0 DEG C LINE. THIS OBSERVATION WAS TAKEN FROM AIRCRAFT
BEFORE THE STRONGER LARGE SCALE FORCING FOR ASCENT BUILT OVER THE
AREA...WHICH SHOULD ONLY RESULT IN COOLING ALOFT. AS A RESULT WENT
AHEAD AND ISSUED A WINTER WEATHER ADVISORY FOR THE DFW METROPLEX
AND LOCATIONS TO THE EAST AND NORTHEAST AS THESE LOCATIONS ARE THE
MOST LIKELY TO SEE LIGHT ACCUMULATIONS OF SNOW WITH SOME SLEET
MIXED IN THIS MORNING.
IN TERMS OF AMOUNTS...SNOW OR SLEET AMOUNTS ARE EXPECTED TO VARY
WITHIN THE ADVISORY FROM TRACE AMOUNTS UP TO ONE HALF INCH. THE
VARIATION IS BECAUSE MOST PRECIPITATION IS EXPECTED TO DEVELOP IN
A BANDED FORM WHICH MEANS LOCATIONS WITHIN SNOW BANDS WILL LIKELY
SEE WINTRY PRECIPITATION ACCUMULATE...WHILE THOSE AREAS NOT
INCLUDED IN BANDS MAY SEE LIGHT PRECIPITATION...OR NOTHING AT ALL.
BANDED PRECIPITATION IS FAVORED BECAUSE THE GFS AND NAM BOTH
INDICATE THAT PRECIPITATION IN THE WINTER WEATHER ADVISORY AREA
WILL BE ENHANCED BY FRONTOGENETIC FORCING...MAXIMIZED IN THE H800
TO H700 LAYER. ABOVE 700 MB...BOTH MODELS ALSO INDICATE A
RELATIVELY DEEP LAYER OF NEGATIVE SATURATED EPV (EQUIVALENT
GEOSTROPHIC POTENTIAL VORTICITY) WHICH INDICATES THAT VERTICAL
MOTIONS INITIATED AT THE BOTTOM OF THIS LAYER WILL RESULT IN A
RELEASE OF EITHER CONVECTIVE OR SLANTWISE INSTABILITY. THERE IS A
SHALLOW LAYER OF THETA-E TEMPERATURE DECREASE WITH HEIGHT WITHIN
THIS LAYER...SO A MIX OF CELLULAR AND BANDED PRECIPITATION IS
LIKELY TO OCCUR. EITHER WAY...THIS TYPE OF FORCING AND INSTABILITY
COMBINATION OFTEN FAVORS LARGE GRADIENTS OF WINTRY ACCUMULATION
AND THAT IS WHAT IS EXPECTED ACROSS NORTH TX THIS MORNING.
IN TERMS OF IMPACTS...WENT AHEAD WITH THE WINTER WEATHER ADVISORY
WITHOUT 100 PERCENT CONFIDENCE THAT LOCATIONS IN THE ADVISORY WILL
ALL SEE ACCUMULATING WINTRY PRECIPITATION. THESE ARE SIMPLY THE
AREAS THAT HAVE THE BEST DIAGNOSED COMBINATION OF FORCING AND
MESOSCALE ENHANCEMENTS THIS MORNING. THE ADVISORY WAS ISSUED
BEFORE RADAR RETURNS HAD DEVELOPED OVER THE ADVISORY AREA TO GIVE
EVERYONE WAKING UP EARLY THIS MORNING A HEADS UP ON THE THREAT OF
WINTRY WEATHER IMPACTING THE MORNING COMMUTE. ASSUMING BANDED
WINTRY PRECIPITATION DEVELOPS OVER THE METROPLEX AROUND 5 AM AS
EXPECTED...THIS IS EXPECTED TO HAVE A VERY NEGATIVE IMPACT ON THE
MORNING RUSH HOUR...POSSIBLY CAUSING SIGNIFICANT DELAYS FOR THE
MORNING COMMUTE. BECAUSE TEMPERATURES ARE HOVERING RIGHT AROUND
FREEZING...MOST ROAD SURFACES IN CONTACT WITH THE GROUND SHOULD
SEE MOST SNOW AND SLEET MELT UPON LANDING AS GROUND TEMPERATURES
REMAIN WELL ABOVE FREEZING. BRIDGES AND OVERPASSES HOWEVER ARE
LIKELY TO RETAIN WINTRY ACCUMULATIONS THIS MORNING...RESULTING IN
ICY CONDITIONS ON ELEVATED ROADWAYS...ESPECIALLY AS TRAFFIC DRIVES
OVER IT...COMPACTING ANY ACCUMULATIONS INTO ICE. WINTRY
PRECIPITATION IS EXPECTED TO MOVE NORTHEAST OR DISSIPATE FOR THE
MOST PART AFTER 9 AM CST. LEFT THE ADVISORY GOING THROUGH 10 AM AS
IT MAY TAKE AN HOUR OR SO AFTER WINTRY PRECIPITATION CEASES BEFORE
ROAD CONDITIONS IMPROVE.
REMAINDER OF THE FORECAST...ALL 15/00Z GUIDANCE INDICATES THAT THE
LARGE UPPER TROUGH TO OUR WEST WILL REMAIN POSITIVELY TILTED AS IT
MOVES OVER THE SOUTH PLAINS OVERNIGHT INTO WEDNESDAY MORNING. THIS
WILL RESULT IN SOME LIGHT RAINFALL WEDNESDAY MORNING SOUTHEAST OF A
CANTON TO WACO LINE ASSUMING THE MODELS ARE RESOLVING THIS TROUGHS
EVOLUTION WELL. WITH NO GUIDANCE OFFERING UP THE CLOSED LOW
SOLUTION ANYMORE...DO NOT HAVE ANYTHING IN THE FORECAST TO HANDLE
THIS NOW UNLIKELY ALTERNATIVE SCENARIO. IT SEEMS THAT AFTER THIS
MORNINGS COMPACT SHORTWAVE TROUGH MOVES NORTHEAST...THE LOWER
TROPOSPHERE WILL BECOME DOMINATED ONCE AGAIN BY COLD AIR ADVECTION
WHICH WOULD SERVE TO KEEP THE TROUGH POSITIVELY TILTED AS IT MOVED
OVER THE CWA. ONE IMPORTANT CAVEAT HERE...WILL HAVE TO SEE HOW
LONG AND INTENSE PRECIPITATION ACTUALLY IS ACROSS NORTH...CENTRAL
AND EAST TX TODAY. IF PRECIPITATION HANGS AROUND LONGER THAN
EXPECTED OR IS JUST MORE INTENSE THAN EXPECTED...PRECIPITATION
WILL RELEASE MORE LATENT HEAT INTO THE MIDDLE TROPOSPHERE THAN THE
MODELS WERE PLANNING ON. WITH NO GUIDANCE FAVORING THE CUT-OFF LOW
SOLUTION ANYMORE...ITS HARD TO IMAGINE WE GET ENOUGH LATENT HEAT
RELEASE TO RAISE THICKNESSES ENOUGH DOWNSTREAM TO HAVE AN IMPACT
ON THE TILT OF THIS TROUGH. HOWEVER IT IS THE ONE THING TO WATCH
FOR DURING THE DAY TODAY...IF DEVELOPING PRECIPITATION RESULTS IN
RIDGING OVER EAST TX...THE UPPER CLOUD COULD MAKE AN ATTEMPT AT
BECOMING NEUTRALLY TILTED OR CUTTING OFF AS IT MOVES TOWARDS THE
CWA OVER THE NEXT 24 HRS. WHILE UNLIKELY...WE WILL NEED TO WATCH
FOR THIS JUST IN CASE THE MODELS HAVE MISSED SOMETHING IMPORTANT
HERE.
THURSDAY AND BEYOND...ONCE THIS UPPER TROUGH MOVES EAST OF THE
SOUTH PLAINS...WE WILL MAINTAIN A DRY FORECAST THROUGH EARLY NEXT
WEEK. TEMPERATURES WILL SLOWLY MODERATE BEHIND THE TROUGH...WITH
HIGHS MAKING A RUN AT 60 DEGREES BY SATURDAY AFTERNOON. WE ARE
STILL LOOKING AT A STRONG COLD FRONT TO KICK OFF THE UPCOMING WORK
WEEK. THE ECMWF IS BACK TO INDICATING A FAIRLY ROBUST PUNCH OF DRY
ARCTIC AIR WHILE THE GFS CONTINUES TO ADVERTISE A COOL BUT
MODIFIED AIRMASS SINKING SOUTH THROUGH THE PLAINS. WENT AHEAD WITH
THE COLDER END OF THE SPECTRUM OF AVAILABLE GUIDANCE BUT MAY HAVE
TO GO EVEN LOWER WITH TEMPS IF THE ECMWF VERIFIES.
CAVANAUGH
&&
.PRELIMINARY POINT TEMPS/POPS...
DALLAS-FT. WORTH, TX 35 27 50 33 53 / 60 10 10 10 0
WACO, TX 35 27 51 30 55 / 50 10 20 10 0
PARIS, TX 34 25 46 29 51 / 60 10 10 10 0
DENTON, TX 36 26 49 29 51 / 60 10 10 10 0
MCKINNEY, TX 35 26 47 29 51 / 60 10 10 10 0
DALLAS, TX 37 28 51 34 53 / 60 10 10 10 0
TERRELL, TX 35 26 48 30 53 / 60 10 10 10 0
CORSICANA, TX 34 28 49 31 54 / 50 10 20 10 0
TEMPLE, TX 35 28 50 30 54 / 40 10 20 10 0
MINERAL WELLS, TX 37 24 52 28 55 / 30 10 10 10 0
&&
.FWD WATCHES/WARNINGS/ADVISORIES...
WINTER WEATHER ADVISORY UNTIL 2 PM CST THIS AFTERNOON FOR
TXZ105>107-119>123-133>135-144>146.
WINTER WEATHER ADVISORY UNTIL NOON CST TODAY FOR TXZ092>095-
102>104-117-118-130>132-148.
&&
$$
85/85
AREA FORECAST DISCUSSION
NWS FORT WORTH TX
1144 AM CST TUE JAN 15 2013
.AVIATION...
CIGS ACROSS THE METROPLEX TAF SITES ARE GENERALLY VFR OR ARE IN THE
PROCESS OF LIFTING TO VFR SHORTLY. MAIN AREA OF DRIZZLE AND
FREEZING DRIZZLE IS TO THE SOUTH OF TAF SITES AND SHOULD REMAIN
THERE. THEREFORE NOT EXPECTING ANY ADDITIONAL WINTER ISSUES AT TAF
SITES...AND A DRY FORECAST WITH NO CONCERNS IS EXPECTED TONIGHT
AND TOMORROW. CIGS WILL CONTINUE TO LIFT DURING THE AFTERNOON AND
OVERNIGHT HOURS AS DRIER AIR MOVES INTO THE AREA. WINDS WILL BE
NORTH NEAR 10KT BECOMING WEST TONIGHT.
FOR WACO...IFR CIGS WILL GRADUALLY LIFT DURING THE AFTERNOON HOURS
TO MVFR...AND VFR IS EXPECTED BY SUNSET. LIGHT DRIZZLE OR MIST IS
OCCURRING NOW...BUT SHOULD TAPER OFF BY MID AFTERNOON. NORTH WINDS
AT 10 KT WILL BECOME WEST BY MORNING.
TR.92
&&
.UPDATE...
LATEST ISENTROPIC PLOTS FROM THE RAP CONTINUE TO SHOW WEAK UPGLIDE
THROUGH 700 MB PERSISTING FOR MOST OF THE MORNING AND EARLY
AFTERNOON. FORECAST SOUNDINGS DEPICT DRYING IN THE UPPER LEVELS OF
THE ATMOSPHERE AND THIS WEAK LIFT WOULD BE SUPPORTIVE OF DRIZZLE.
STARTING TO SEE LIGHT RETURNS WEST OF INTERSTATE 35...BUT NOTHING
HAS BEEN REPORTED YET AT ANY OF THE AREA OBSERVATION SITES. NOT
MUCH PRECIP FELL IN THESE LOCATIONS AND AS THIS WEAK LIFT IN THE
LOWEST ATMOSPHERE SHIFTS EAST...DRIZZLE IS LIKELY TO FORM ACROSS
THE AREA WHICH PICKED UP OVERNIGHT PRECIP. LATEST RAP ALSO KEEPS
TEMPERATURES BELOW FREEZING UNTIL NOON OR 1 PM...AND WE EXTENDED
THE ADVISORY UNTIL NOON. THE FREEZING DRIZZLE WOULD BE PROBLEMATIC
AS THIS WOULD FALL ON TOP OF THE SLEET/SNOW AND MAKE THE AREA
BRIDGES AND OVERPASSES EVEN MORE HAZARDOUS.
HAMPSHIRE
&&
.PREV DISCUSSION... /ISSUED 448 AM CST TUE JAN 15 2013/
SHORT TERM WINTER WEATHER CONCERNS...
ONCE AGAIN WE HAVE A THREAT FOR WINTRY PRECIPITATION TO DEVELOP
OVER PORTIONS OF NORTH AND CENTRAL TX EARLY THIS MORNING. THE LONG
WAVE TROUGH OVER THE WESTERN CONUS HAS BECOME POSITIVELY TILTED
ALREADY THIS MORNING AND ITS AXIS NOW ORIENTED FROM NORTHERN
MINNESOTA SOUTHWEST TO THE SOUTHERN NEW MEXICO AND ARIZONA BORDER.
THE TROUGH WAS SHOWING SIGNS OF MOVING EAST ALREADY EARLY THIS
MORNING. THIS EASTWARD MOVEMENT...COMBINED WITH A COMPACT
SHORTWAVE TROUGH EMBEDDED IN THE SOUTHWEST FLOW ALOFT OVER THE
SOUTHERN HIGH PLAINS IS LIKELY PROVIDING THE LARGE SCALE FORCING
FOR ASCENT EVIDENT ON WATER VAPOR IMAGERY OVER NORTH TX AT THIS
TIME. EVIDENCE OF LARGE SCALE FORCING FOR ASCENT WAS SHOWING UP IN
IR SATELLITE IMAGERY AND VWP PROFILES EARLY THIS MORNING AS WELL.
IR SATELLITE IMAGERY INDICATES COOLING CLOUD TOPS OVER MUCH OF
NORTH AND CENTRAL TX WHILE REGIONAL RADAR VWP SHOWS LOW LEVEL FLOW
VEERING STRONGLY WITH HEIGHT...A SIGN OF WARM AIR ADVECTION AND
ISENTROPIC LIFT. ALL OF THIS IS EVIDENCE THAT WE WILL LIKELY SEE
RADAR RETURNS BLOSSOM AROUND NORTH AND CENTRAL TX THIS MORNING AS
PERSISTENT ASCENT EVENTUALLY RESULTS IN SCATTERED PRECIPITATION
DEVELOP OVER THE REGION.
CONFIDENCE IS FAIRLY HIGH THAT PRECIPITATION WILL DEVELOP OVER
MOST AREAS ALONG AND SOUTHEAST OF A BONHAM TO FORT WORTH TO
LAMPASAS LINE EARLY THIS MORNING. AS A RESULT WENT AHEAD AND
BUMPED UP POPS INTO THE 30 TO 50 PERCENT RANGE FOR THESE LOCATIONS
THROUGH THE MORNING HOURS. CONFIDENCE WAVERS WHEN DETERMINING WHAT
FORM THIS PRECIPITATION WILL FALL AS IT DEVELOPS AND MOVES
NORTHEAST OVER THESE LOCATIONS. THERE ARE SEVERAL FACTORS TO
CONSIDER...AND ILL DETAIL SOME OF THOSE BELOW.
THE EASIEST THING TO NOTICE IS THAT SURFACE TEMPERATURES ARE A
GOOD 5 DEGREES WARMER THAN EXPECTED TO START OFF THE FORECAST
TODAY. THIS IS ONE GOOD CONSEQUENCE OF THE MODELS UNDERESTIMATING
THE STRENGTH OF LARGE SCALE FORCING FOR ASCENT OVER THE
REGION...CLOUDS BUILT IN EARLIER THAN EXPECTED WHICH PREVENTED
TEMPERATURES FROM FALLING BELOW FREEZING SOUTH OF INTERSTATE
20...AT LEAST AS OF 4 AM CST. THIS AT LEAST ALLEVIATES CONCERNS
FOR FREEZING RAIN OVER THE WACO/KILLEEN/TEMPLE AREAS EARLY THIS
MORNING.
FURTHER NORTH...PRECIPITATION IS EXPECTED TO DEVELOP AROUND OR
AFTER 5 AM CST NEAR THE DFW METROPLEX...WHILE 4 AM SURFACE
OBSERVATIONS INDICATED THAT THE WET BULB ZERO LINE WAS LOCATED AS
FAR SOUTH AS CLEBURNE AND WAXAHACHIE. 05Z AMDAR AIRCRAFT SOUNDINGS
INDICATED THAT THE THERMAL PROFILE OVER THE METROPLEX WAS MOSTLY
SUPPORTIVE OF SNOW...WITH A SURFACE TO 700 MB ISOTHERMAL LAYER
HUGGING THE 0 DEG C LINE. THIS OBSERVATION WAS TAKEN FROM AIRCRAFT
BEFORE THE STRONGER LARGE SCALE FORCING FOR ASCENT BUILT OVER THE
AREA...WHICH SHOULD ONLY RESULT IN COOLING ALOFT. AS A RESULT WENT
AHEAD AND ISSUED A WINTER WEATHER ADVISORY FOR THE DFW METROPLEX
AND LOCATIONS TO THE EAST AND NORTHEAST AS THESE LOCATIONS ARE THE
MOST LIKELY TO SEE LIGHT ACCUMULATIONS OF SNOW WITH SOME SLEET
MIXED IN THIS MORNING.
IN TERMS OF AMOUNTS...SNOW OR SLEET AMOUNTS ARE EXPECTED TO VARY
WITHIN THE ADVISORY FROM TRACE AMOUNTS UP TO ONE HALF INCH. THE
VARIATION IS BECAUSE MOST PRECIPITATION IS EXPECTED TO DEVELOP IN
A BANDED FORM WHICH MEANS LOCATIONS WITHIN SNOW BANDS WILL LIKELY
SEE WINTRY PRECIPITATION ACCUMULATE...WHILE THOSE AREAS NOT
INCLUDED IN BANDS MAY SEE LIGHT PRECIPITATION...OR NOTHING AT ALL.
BANDED PRECIPITATION IS FAVORED BECAUSE THE GFS AND NAM BOTH
INDICATE THAT PRECIPITATION IN THE WINTER WEATHER ADVISORY AREA
WILL BE ENHANCED BY FRONTOGENETIC FORCING...MAXIMIZED IN THE H800
TO H700 LAYER. ABOVE 700 MB...BOTH MODELS ALSO INDICATE A
RELATIVELY DEEP LAYER OF NEGATIVE SATURATED EPV (EQUIVALENT
GEOSTROPHIC POTENTIAL VORTICITY) WHICH INDICATES THAT VERTICAL
MOTIONS INITIATED AT THE BOTTOM OF THIS LAYER WILL RESULT IN A
RELEASE OF EITHER CONVECTIVE OR SLANTWISE INSTABILITY. THERE IS A
SHALLOW LAYER OF THETA-E TEMPERATURE DECREASE WITH HEIGHT WITHIN
THIS LAYER...SO A MIX OF CELLULAR AND BANDED PRECIPITATION IS
LIKELY TO OCCUR. EITHER WAY...THIS TYPE OF FORCING AND INSTABILITY
COMBINATION OFTEN FAVORS LARGE GRADIENTS OF WINTRY ACCUMULATION
AND THAT IS WHAT IS EXPECTED ACROSS NORTH TX THIS MORNING.
IN TERMS OF IMPACTS...WENT AHEAD WITH THE WINTER WEATHER ADVISORY
WITHOUT 100 PERCENT CONFIDENCE THAT LOCATIONS IN THE ADVISORY WILL
ALL SEE ACCUMULATING WINTRY PRECIPITATION. THESE ARE SIMPLY THE
AREAS THAT HAVE THE BEST DIAGNOSED COMBINATION OF FORCING AND
MESOSCALE ENHANCEMENTS THIS MORNING. THE ADVISORY WAS ISSUED
BEFORE RADAR RETURNS HAD DEVELOPED OVER THE ADVISORY AREA TO GIVE
EVERYONE WAKING UP EARLY THIS MORNING A HEADS UP ON THE THREAT OF
WINTRY WEATHER IMPACTING THE MORNING COMMUTE. ASSUMING BANDED
WINTRY PRECIPITATION DEVELOPS OVER THE METROPLEX AROUND 5 AM AS
EXPECTED...THIS IS EXPECTED TO HAVE A VERY NEGATIVE IMPACT ON THE
MORNING RUSH HOUR...POSSIBLY CAUSING SIGNIFICANT DELAYS FOR THE
MORNING COMMUTE. BECAUSE TEMPERATURES ARE HOVERING RIGHT AROUND
FREEZING...MOST ROAD SURFACES IN CONTACT WITH THE GROUND SHOULD
SEE MOST SNOW AND SLEET MELT UPON LANDING AS GROUND TEMPERATURES
REMAIN WELL ABOVE FREEZING. BRIDGES AND OVERPASSES HOWEVER ARE
LIKELY TO RETAIN WINTRY ACCUMULATIONS THIS MORNING...RESULTING IN
ICY CONDITIONS ON ELEVATED ROADWAYS...ESPECIALLY AS TRAFFIC DRIVES
OVER IT...COMPACTING ANY ACCUMULATIONS INTO ICE. WINTRY
PRECIPITATION IS EXPECTED TO MOVE NORTHEAST OR DISSIPATE FOR THE
MOST PART AFTER 9 AM CST. LEFT THE ADVISORY GOING THROUGH 10 AM AS
IT MAY TAKE AN HOUR OR SO AFTER WINTRY PRECIPITATION CEASES BEFORE
ROAD CONDITIONS IMPROVE.
REMAINDER OF THE FORECAST...ALL 15/00Z GUIDANCE INDICATES THAT THE
LARGE UPPER TROUGH TO OUR WEST WILL REMAIN POSITIVELY TILTED AS IT
MOVES OVER THE SOUTH PLAINS OVERNIGHT INTO WEDNESDAY MORNING. THIS
WILL RESULT IN SOME LIGHT RAINFALL WEDNESDAY MORNING SOUTHEAST OF A
CANTON TO WACO LINE ASSUMING THE MODELS ARE RESOLVING THIS TROUGHS
EVOLUTION WELL. WITH NO GUIDANCE OFFERING UP THE CLOSED LOW
SOLUTION ANYMORE...DO NOT HAVE ANYTHING IN THE FORECAST TO HANDLE
THIS NOW UNLIKELY ALTERNATIVE SCENARIO. IT SEEMS THAT AFTER THIS
MORNINGS COMPACT SHORTWAVE TROUGH MOVES NORTHEAST...THE LOWER
TROPOSPHERE WILL BECOME DOMINATED ONCE AGAIN BY COLD AIR ADVECTION
WHICH WOULD SERVE TO KEEP THE TROUGH POSITIVELY TILTED AS IT MOVED
OVER THE CWA. ONE IMPORTANT CAVEAT HERE...WILL HAVE TO SEE HOW
LONG AND INTENSE PRECIPITATION ACTUALLY IS ACROSS NORTH...CENTRAL
AND EAST TX TODAY. IF PRECIPITATION HANGS AROUND LONGER THAN
EXPECTED OR IS JUST MORE INTENSE THAN EXPECTED...PRECIPITATION
WILL RELEASE MORE LATENT HEAT INTO THE MIDDLE TROPOSPHERE THAN THE
MODELS WERE PLANNING ON. WITH NO GUIDANCE FAVORING THE CUT-OFF LOW
SOLUTION ANYMORE...ITS HARD TO IMAGINE WE GET ENOUGH LATENT HEAT
RELEASE TO RAISE THICKNESSES ENOUGH DOWNSTREAM TO HAVE AN IMPACT
ON THE TILT OF THIS TROUGH. HOWEVER IT IS THE ONE THING TO WATCH
FOR DURING THE DAY TODAY...IF DEVELOPING PRECIPITATION RESULTS IN
RIDGING OVER EAST TX...THE UPPER CLOUD COULD MAKE AN ATTEMPT AT
BECOMING NEUTRALLY TILTED OR CUTTING OFF AS IT MOVES TOWARDS THE
CWA OVER THE NEXT 24 HRS. WHILE UNLIKELY...WE WILL NEED TO WATCH
FOR THIS JUST IN CASE THE MODELS HAVE MISSED SOMETHING IMPORTANT
HERE.
THURSDAY AND BEYOND...ONCE THIS UPPER TROUGH MOVES EAST OF THE
SOUTH PLAINS...WE WILL MAINTAIN A DRY FORECAST THROUGH EARLY NEXT
WEEK. TEMPERATURES WILL SLOWLY MODERATE BEHIND THE TROUGH...WITH
HIGHS MAKING A RUN AT 60 DEGREES BY SATURDAY AFTERNOON. WE ARE
STILL LOOKING AT A STRONG COLD FRONT TO KICK OFF THE UPCOMING WORK
WEEK. THE ECMWF IS BACK TO INDICATING A FAIRLY ROBUST PUNCH OF DRY
ARCTIC AIR WHILE THE GFS CONTINUES TO ADVERTISE A COOL BUT
MODIFIED AIRMASS SINKING SOUTH THROUGH THE PLAINS. WENT AHEAD WITH
THE COLDER END OF THE SPECTRUM OF AVAILABLE GUIDANCE BUT MAY HAVE
TO GO EVEN LOWER WITH TEMPS IF THE ECMWF VERIFIES.
CAVANAUGH
&&
.PRELIMINARY POINT TEMPS/POPS...
DALLAS-FT. WORTH, TX 36 27 50 33 53 / 60 10 10 10 0
WACO, TX 35 27 51 30 55 / 50 10 20 10 0
PARIS, TX 36 25 46 29 51 / 60 10 10 10 0
DENTON, TX 37 26 49 29 51 / 60 10 10 10 0
MCKINNEY, TX 36 26 47 29 51 / 60 10 10 10 0
DALLAS, TX 35 28 51 34 53 / 60 10 10 10 0
TERRELL, TX 34 26 48 30 53 / 60 10 10 10 0
CORSICANA, TX 34 28 49 31 54 / 50 10 20 10 0
TEMPLE, TX 35 28 50 30 54 / 40 10 20 10 0
MINERAL WELLS, TX 38 24 52 28 55 / 30 10 10 10 0
&&
.FWD WATCHES/WARNINGS/ADVISORIES...
WINTER WEATHER ADVISORY UNTIL NOON CST TODAY FOR TXZ092>095-
102>107-117>123-130>135-144>146-148.
&&
$$
/