Forecast Discussions mentioning any of
"HRRR" "RAP" "RR" "RUC13" "RUC" received at GSD on 12/19/13
AREA FORECAST DISCUSSION
NWS DENVER/BOULDER CO
959 AM MST TUE DEC 17 2013
.UPDATE...
&&
.SHORT TERM...CURRENT FORECASTS SEEM REASONABLE. WEST NORTHWEST
FLOW CURRENTLY OVER THE REGION. SOME GUSTS FROM 25 TO 30 KTS
CURRENTLY IN AND NEAR FOOTHILLS...THOUGH NOT THAT WIDESPREAD.
THERE WILL BE SOME MIXING BY THE AFTERNOON WHICH WILL HELP
WESTERLY WINDS SPREAD FURTHER EAST ALONG THE URBAN CORRIDOR WITH
A MORE SOUTHERLY DIRECTION AWAY FROM THE URBAN CORRIDOR. WARMER
AIRMASS AND MIXING WILL HELP WITH WARMUP TODAY...WITH LOWER TO MID
60S POSSIBLE ACROSS THE PLAINS. SOME INCREASE IN WIND TONIGHT IN
AND NEAR FOOTHILLS AS FLOW ALOFT BECOMES A BIT MORE WESTERLY AND
CROSS MOUNTAIN FLOW INCREASES TO AROUND 40 KTS. OVERNIGHT
TEMPERATURES TO BE FAIRLY MILD WITH SOME MODERATION IN LOW LYING
AREAS.
.AVIATION...WINDS CURRENTLY SOUTHEAST AT KDEN AND KAPA WHILE
WESTERLY AT KBJC. STILL EXPECTING SOME MIXING OF THE WESTERLY
WINDS ACROSS THE AREA AIRPORTS BY 20Z. LATEST RAP AND HRRR
INDICATING WINDS AT KDEN AND KAPA TO CONTINUE SOUTHEAST FOR MUCH
OF THE AFTERNOON. FOR NOW WILL CONTINUE THE TREND OF THE CURRENT
TAFS...THINKING THAT THE MIXING WILL OVERCOME THE SOUTHEAST
DIRECTION THIS AFTERNOON. ENHANCED DRAINAGE FLOW EXPECTED THIS
EVENING. VFR WILL CONTINUE. SOME POTENTIAL FOR WAVE CLOUD IN AND
NEAR FOOTHILLS AFTER 08Z. CEILINGS SHOULD REMAIN ABOVE 12000 FEET
AGL.
&&
.PREV DISCUSSION... /ISSUED 411 AM MST TUE DEC 17 2013/
SHORT TERM...WNW FLOW CONTINUES TODAY WITH LITTLE CHANGE TO THE
WIND FIELD OTHER THAN WEAK MIXING WITH HEATING DURING THE DAY IN
THE LOWER ELEVATIONS. TEMPERATURES SHOULD GET A LITTLE WARMER THAN
YESTERDAY. STILL A FEW WAVE CLOUDS AROUND...COULD BE SOME
ENHANCEMENT FOR A WHILE THIS MORNING. BETWEEN TODAYS WARMING AND
CONTINUED BREEZES OVERNIGHT LOWS SHOULD ALSO CONTINUE A WARMING
TREND...PRETTY MILD IN MOST AREAS AND COLDER BUT STILL MODERATING
A BIT IN THE LOW SPOTS.
LONG TERM...ON WEDNESDAY...A MODERATE TO STRONG W/SWLY FLOW
ALOFT WILL BE OVER COLORADO...WITH A SURFACE TROUGH DEVELOPING
OVER THE EASTERN PLAINS THROUGH THE DAY. THIS WILL ADD UP TO AN
UNSEASONABLE MILD AFTN ESPECIALLY IN AND NEAR THE FRONT RANGE
FOOTHILLS WHERE DOWNSLOPE WLY WINDS WILL DEVELOP. TEMPERATURES ARE
PROGGED TO CLIMB INTO THE MID 60S FOR DENVER...THE RECORD HIGH FOR
THE DATE IS 66 DEGREES WHICH COULD BE BROKEN. THE NAM12/GFS40 SPATIAL
CROSS-SECTIONS CONTINUES TO DEVELOP STRONG GUSTY WINDS IN THE
MOUNTAINS AND HIGHER FOOTHILLS WITH A 50 KT CROSS-MTN COMPONENT AT
750 MB. DO NOT EXPECTED WARNING CRITERIA WINDS BUT OVERNIGHT LOWS
IN THE FOOTHILLS WILL BE VERY MILD WITH SOME GUSTS TO 50 MPH
POSSIBLE. THE FLOW ALOFT WILL CONTINUE TO INCREASE ON
THURSDAY...WITH A 90 KT JET OVERHEAD. THE FLOW ALOFT WILL BE
SOUTHWESTERLY WITH THE INCOMING TROUGH SLOWS DOWN AND SPLITS. THE
NORTHERN BRANCH WILL MOVE ACROSS THE NRN TIER STATES WHILE THE SRN
BRANCH DEVELOPING INTO A CLOSED LOW OVER SRN CA. IT WILL BE FAIRLY
MILD THURSDAY MORNING AHEAD OF AN APPROACHING COLD FRONT WHICH
SHOULD MOVE IN THE DENVER AREA AROUND 18Z. OVERALL THE DYNAMICS
ALOFT ARE FAIRLY WEAK AS THE SYSTEM SPLITS TO THE NORTH AND WEST
LATE THURSDAY AND THURSDAY NIGHT. SPATIAL CROSS-SECTIONS DO SHOW
SOME UPSLOPE DEVELOPING ALONG THE FRONT RANGE LATE THURSDAY AFTN
AND EVENING. DECENT MOISTURE AS WELL AOB 700 MB...BUT BOTH THE
UPSLOPE AND MOISTURE DECREASE FAIRLY RAPIDLY AFTER 06Z THURSDAY
NIGHT. BEST CHC OF SNOW MAY BE ALONG THE NRN BORDER WHERE LOW
LEVEL UPSLOPE AND UPPER LEVEL LIFT ASSOCIATED WITH THE JET
COINCIDE. SNOW AMOUNTS WILL BE LIGHT OVERALL BUT BRIEF ENHANCED
BANDS COULD DEVELOP IN THIS AREA. IT WILL BE MUCH COOLER ON
FRIDAY...BUT THE LOWER LEVELS APPEAR FAIRLY DRY...SO SNOW
POTENTIAL SHOULD BE DONE ACROSS THE NERN PLAINS AFTER 12Z FRIDAY.
TEMPERATURES ON FRIDAY WILL BE 25 DEGREES COOLER THAN THOSE ON
WEDNESDAY. NO TEMPERATURE RECOVERY EXPECTED ON SATURDAY AS THE
GFS DOES SHOW A SECONDARY PUSH OF COLD AIR LATE SATURDAY AFTN
ALONG WITH A BRIEF PERIOD OF UPSLOPE. THIS MAY RESULT IN A SLGT
CHC OF SNOW LATE SATURDAY AFTN/EVNG ALONG THE FRONT RANGE. THE SRN
BRANCH OF THE SPLIT TROUGH IS PROGGED TO PASS WELL SOUTH OF
COLORADO AS IT MOVES ACROSS NRN MX FRIDAY NIGHT AND INTO NCNTRL TX
BY 00Z SUNDAY. THERE WILL BE JUST A BRIEF PERIOD OF WEAK QG ASCENT
AOA 500 MB ASSOCIATED WITH THE PASSAGE OF THE NRN BRANCH OF THE
TROUGH AXIS AROUND 00Z SUNDAY...THEN IT BREAKS UP. ON SUNDAY IT
WILL REMAIN MOSTLY CLOUDY WITH MOST OF THE MOISTURE AOA 650 MB.
THE LOWER LEVELS WILL BE DRY WITH A W/NWLY DOWNSLOPE FLOW IN
PLACE. AS A RESULT...SHOULD SEE TEMPERATURES START TO MODERATE TO
NEAR SEASONAL NORMALS ON SUNDAY.
AVIATION...VFR THROUGH TONIGHT. WEST WINDS GUSTING IN THE 20 TO
30 KNOT RANGE NEAR THE FOOTHILLS...WITH WEST TO NORTHWEST WINDS
MIXING TO THE SURFACE AT KDEN/KAPA IN THE AFTERNOON WITH GUSTS
AROUND 20 KNOTS AT KDEN. DECREASING WINDS AWAY FROM THE FOOTHILLS
WITH A TREND BACK TOWARD SOUTHERLY THIS EVENING...BUT SOME
INCREASE AGAIN BY WEDNESDAY MORNING.
&&
.BOU WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...D-L
LONG TERM....COOPER
AVIATION...D-L
AREA FORECAST DISCUSSION
NWS NEW YORK NY
413 PM EST TUE DEC 17 2013
.SYNOPSIS...
WEAK LOW PRESSURE WILL PASS JUST SOUTH AND EAST OF LONG ISLAND
INTO EARLY THIS EVENING...AND THEN PULL AWAY INTO THE GULF OF
MAINE LATER TONIGHT. HIGH PRESSURE WILL THEN DOMINATE FROM
WEDNESDAY INTO THURSDAY NIGHT. A SLOW MOVING FRONTAL SYSTEM WILL
AFFECT THE AREA FRIDAY THROUGH MONDAY.
&&
.NEAR TERM /UNTIL 6 AM WEDNESDAY MORNING/...
MID AFTERNOON MESOANALYSIS SHOWS THE WEAK LOW NOW SOUTH OF CENTRAL
LONG ISLAND AND EAST OF THE CENTRAL NJ AND EXHIBITING A DUAL
COASTAL FRONT SETUP...ONE FROM FIRE ISLAND ACROSS THE SOUTH FORK
OF LONG ISLAND...AND ANOTHER ALONG THE SE CT COAST.
FOLLOWED LATEST RAP MODEL FOR THERMAL PROFILES ALOFT BUT WITH A
LITTLE EXTRA H9 WARMING...WHICH ALONG WITH COASTAL FRONT SETUP
MEANS THAT AREAS NORTH/WEST OF NYC SHOULD REMAIN NEARLY ALL
SNOW...WITH ONLY A BRIEF WARM INTRUSION ALOFT ALONG THE CT COAST.
FROM NYC METRO EAST ACROSS MOST OF LONG ISLAND BETWEEN THE TWO
COASTAL FRONTS...WINDS ARE STARTING TO BACK WHICH WILL BRING
COLDER LOW LEVEL AIR BACK ACROSS LONG ISLAND...WITH A GRADUAL
CHANGE FROM FREEZING RAIN/SLEET IN NYC METRO BACK TO LIGHT
SNOW...AND FROM RAIN TO FREEZING RAIN AND SLEET ACROSS MOST OF
LONG ISLAND BEFORE ENDING THIS EVENING. ADVYS HAVE BEEN EXTENDED
TO THE SOUTH SHORE OF WRN LONG ISLAND FOR THE FREEZING RAIN...AND
IN TIME FOR SOUTHERN CT UNTIL 9 PM AND ELSEWHERE UNTIL 7 PM.
SNOWFALL TOTALS FOR MOST PLACES SHOULD STILL RANGE FROM 2-4
INCHES...BUT CANNOT RULE OUT SOME 5 INCH TOTALS OVER SOUTHERN CT.
ALONG THE SOUTH SHORE OF LONG ISLAND...TOTALS SHOULD BE UNDER 2
INCHES...WITH LESS THAN AN INCH ON THE SOUTH FORK.
AFTER PRECIP TAPERS OFF THIS EVENING...MOSTLY CLOUDY SKIES WILL
CONTINUE THROUGH THE NIGHT VIA CYCLONIC LOW LEVEL FLOW AND UPPER
TROUGH PASSAGE. N-NW WINDS WILL ALSO BECOME GUSTY AS THE NIGHT
PROGRESSES. LOWS WILL 20-25 IN NYC METRO AND LONG ISLAND...AND
15-20 ELSEWHERE.
&&
.SHORT TERM /6 AM WEDNESDAY MORNING THROUGH WEDNESDAY NIGHT/...
HIGH PRESSURE WILL BUILD IN TO OUR SOUTH ON WED...WITH A BRISK NW
FLOW BACKING W IN THE AFTERNOON AND GUSTING TO 25-30 MPH.
SHOULD SEE SCT-BKN STRATOCU DEVELOPMENT ESPECIALLY NORTH/WEST OF
NYC. HIGHS WILL STILL BE ABOUT 5 DEG BELOW AVG...WITH MID AND
UPPER 30S.
W WINDS WILL DROP OFF WED NIGHT...WITH CLOUDS CONTINUING
ESPECIALLY INLAND AS A WARM FRONT PASSES WELL TO THE NORTH.
FCST LOWS RANGE FROM 15-20 INLAND TO THE LOWER AND MID 20S
ELSEWHERE. WITH CLOUD COVER AND W FLOW STILL 25 KT JUST OFF THE
DECK DO NOT EXPECT THE BOTTOM TO FALL OUT ON INLAND TEMPS VIA
RADIATIONAL COOLING DESPITE DIMINISHING WINDS AND SNOW PACK.
&&
.LONG TERM /THURSDAY THROUGH TUESDAY/...
FORECAST MODELS CONTINUE TO SHOW GOOD AGREEMENT IN THE OVERALL
SYNOPTIC PATTERN THROUGH THIS PERIOD. WE START THE LONG TERM PERIOD
WITH FAIRLY ZONAL FLOW ALOFT ACROSS THE COUNTRY WITH SURFACE HIGH
PRESSURE ANCHORED OFF THE SOUTHEASTERN COAST. THIS WILL RESULT IN A
MILDER RETURN FLOW UP THE EASTERN SEABOARD...ALLOWING TEMPERATURES
TO REBOUND TO NEAR SEASONAL NORMALS ON THURSDAY BEFORE SETTING US UP
FOR A VERY MILD WEEKEND.
AT THE SURFACE...A SLOW MOVING FRONTAL SYSTEM WILL APPROACH FROM
THE WEST ON FRIDAY THROUGH THE WEEKEND WITH SEVERAL WAVES OF LOW
PRESSURE RIDING ALONG IT. EXPECT ON AND OFF SHOWER ACTIVITY
FROM FRIDAY INTO MONDAY AND POSSIBLY MONDAY EVENING. HOWEVER...WITH
THE SLOW EASTWARD PROGRESSION OF THE FRONT...THE WAVES THAT DEVELOP
AND MOVE ALONG IT WILL REMAIN WELL TO OUR WEST UNTIL SUNDAY NIGHT.
THIS WILL KEEP THE MOST SIGNIFICANT RAINFALL WEST OF THE AREA. THE
FRONT WILL EVENTUALLY PUSH EASTWARD...SLOWLY MOVING ACROSS THE AREA
MONDAY INTO MONDAY EVENING. DO NOT EXPECT ANY ISSUES WITH
PRECIPITATION TYPE UNTIL THE VERY TAIL END OF THINGS LATE MONDAY OR
MONDAY NIGHT AS WE REMAIN IN THE WARM SECTOR THROUGHOUT. THE COLD
AIR PUSHES IN JUST ABOUT THE TIME PRECIPITATION SHUTS OFF...SO WILL
KEEP THE CHANCE OF SNOW TO THE NORTH AND WEST OF NEW YORK CITY AND
THE I-95 CORRIDOR AT THIS TIME.
TEMPERATURES WILL TREND MILDER AND WILL CLIMB ABOVE SEASONAL NORMALS
BY THE END OF THE WEEK. SHAVED A FEW DEGREES OFF GUIDANCE FOR THE
WEEKEND MAXIMUMS...ESPECIALLY FOR AREAS WITH A MARINE FETCH AS WATER
TEMPERATURES IN THE 40S AND PLENTY OF CLOUD COVER WILL MAKE IT
DIFFICULT FOR TEMPERATURES TO CLIMB MUCH ABOVE 55-60. THEN A
SIGNIFICANT CHANGE IN AIR MASS WILL OCCUR ONCE THE NEXT COLD FRONT
PUSHES THROUGH EARLY NEXT WEEK. THIS WILL SEND TEMPERATURES DOWN
BELOW NORMAL INTO THE MIDDLE OF NEXT WEEK.
&&
.AVIATION /21Z TUESDAY THROUGH SUNDAY/...
WEAK LOW PRESSURE CENTER JUST SOUTH OF THE TERMINALS LATE THIS
AFTERNOON SHIFTS EAST INTO EARLY EVENING..
MODERATE TO HIGH CONFIDENCE IN WINDS. GENERALLY N TO NNW AROUND 10
KT INTO THIS EVENING.
MODERATE CONFIDENCE IN VSBYS/CIGS...MAINLY IFR TO MVFR INTO EARLY
EVENING...EVENTUALLY IMPROVING TO VFR BY MIDNIGHT.
MODERATE CONFIDENCE IN PCPN TYPE. SHOULD BE MIXED FOR ALL BUT KSWF.
VERY LITTLE TO NO ADDITIONAL SNOW/SLEET ACCUMULATIONS FROM THIS
POINT ON. PCPN SHOULD END 22-00Z FOR MOST SPOTS.
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: -SNPL OR -SN MIGHT PREVAIL THROUGH 22Z.
KJFK FCSTER COMMENTS: RA INSTEAD OF FZRA COULD OCCUR THROUGH 2230Z.
TEMPO -FZRAPL MIGHT NOT OCCUR. -SN COULD ALSO BE MIXED IN AT TIMES
AFTER 2130Z.
KLGA FCSTER COMMENTS: -SNPL COULD POSSIBLY PREVAIL THROUGH 2230Z
KTEB FCSTER COMMENTS: -SNPL OR -SN MIGHT PREVAIL THROUGH 22Z.
KHPN FCSTER COMMENTS: -SN COULD PREVAIL THROUGH 2230Z.
KISP FCSTER COMMENTS: -SN COULD BE MIXED IN AFTER 23Z.
.OUTLOOK FOR 18Z WEDNESDAY THROUGH SATURDAY...
.WED...VFR. WNW GUSTS 20-25KT
.THU...VFR.
.FRI...MVFR OR LOWER POSSIBLE WITH CHC RAIN OVERNIGHT.
.SAT...MVFR OR LOWER WITH SHRA
.SUN...MVFR OR LOWER WITH SHRA. CHC SW GUSTS 25-30KT AND LLWS.
&&
.MARINE...
SMALL CRAFT ADVISORY CONDITIONS CONTINUE LATE THIS AFTERNOON ON
THE OCEAN AND ERN SOUND/BAYS. SMALL CRAFT ADVISORY CONDITIONS ARE
EXPECTED TO CONTINUE ACROSS OCEAN WATERS LATER TONIGHT INTO WED
NIGHT ON GUSTY W-NW FLOW.
SCA WINDS AND SEAS ARE ALSO LIKELY FRIDAY THROUGH THE WEEKEND
FROM A PROLONGED PERIOD OF SOUTH TO SOUTHWESTERLY FLOW AHEAD OF A
SLOW MOVING FRONTAL SYSTEM.
&&
.HYDROLOGY...
LOW PRESSURE PASSING SOUTH OF LONG ISLAND WILL BRING 1/3 TO 1/2
INCH LIQUID EQUIVALENT QPF. MOST OF THIS SHOULD BE IN THE FORM OF
SNOW...WITH 1-5 INCHES ACCUMULATION...HIGHEST OVER SOUTHERN CT.
&&
.EQUIPMENT...
THE NEW YORK CITY NOAA ALL HAZARDS WEATHER RADIO STATION KWO35 IS
OUT OF SERVICE.
DUE TO INTERFERENCE ISSUES WITH THE U.S. COAST GUARD EMERGENCY
BROADCAST CHANNEL...THE NEW YORK CITY NOAA ALL HAZARDS WEATHER
RADIO STATION KWO35 IS OUT OF SERVICE.
DURING THE TIME...THE TRANSMITTER MAY BE RETURNED TO SERVICE
INTERMITTENTLY FOR USE OF THE NOAA ALL HAZARDS WEATHER RADIO
DURING POTENTIALLY DANGEROUS WEATHER SITUATIONS...FOR ROUTINE
WEEKLY TEST OF THE WARNING SYSTEM...AND TO DETERMINE IF THE
INTERFERENCE ISSUE HAS BEEN RESOLVED.
&&
.OKX WATCHES/WARNINGS/ADVISORIES...
CT...WINTER WEATHER ADVISORY UNTIL 9 PM EST THIS EVENING FOR
CTZ005>012.
NY...WINTER WEATHER ADVISORY UNTIL 7 PM EST THIS EVENING FOR
NYZ067>075-078>080-176>179.
NJ...WINTER WEATHER ADVISORY UNTIL 7 PM EST THIS EVENING FOR NJZ002-
004-006-103>108.
MARINE...SMALL CRAFT ADVISORY UNTIL 6 PM EST THIS EVENING FOR ANZ330-
340.
SMALL CRAFT ADVISORY UNTIL 6 AM EST THURSDAY FOR ANZ350-353-
355.
&&
$$
SYNOPSIS...GOODMAN
NEAR TERM...GOODMAN
SHORT TERM...GOODMAN
LONG TERM...
AVIATION...JC
MARINE...GOODMAN
HYDROLOGY...JC
EQUIPMENT...
AREA FORECAST DISCUSSION
NWS ALBANY NY
1240 PM EST TUE DEC 17 2013
.SYNOPSIS...
A LOW PRESSURE SYSTEM PASSING SOUTH OF THE REGION WILL BRING A
WIDESPREAD LIGHT TO MODERATE SNOWFALL TO THE AREA TODAY. THE SNOW
WILL SPREAD NORTHWARD ACROSS THE AREA DURING THIS MORNING AND IS
EXPECTED TO TAPER OFF THIS EVENING. SCATTERED SNOW SHOWERS ARE
THEN EXPECTED TONIGHT AND WEDNESDAY...ESPECIALLY ACROSS THE HIGHER
TERRAIN. A GRADUAL WARMING TREND IS THEN EXPECTED FOR THE END OF
THE WORKWEEK.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
AS OF 1240 PM EST...THE WINTER WX ADVISORY CONTINUES FROM THE
CAPITAL REGION...MOHAWK VALLEY...SRN VT SOUTHWARD UNTIL 7 PM. A
LULL IN THE PCPN HAS OCCURRED OVER THE CAPITAL REGION...CNTRL
TACONICS...AND BERKSHIRES...BUT THE PCPN IS FILLING BACK IN
QUICKLY OVER THE ERN CATSKILLS...MID HUDSON VALLEY...AND NW
CT...AS THE NEW LOW PRESSURE SYSTEM FORMS E/SE OF KACY. PRESSURE
FALLS OF 3-5 HPA/3 HRS ARE OCCURRING JUST NORTHEAST OF THE LOW
OVER SOUTHERN LONG ISLAND. THE CYCLONE SHOULD QUICKLY TRACK
NORTHEAST THIS PM.
SNOWFALL TOTAL POTENTIAL OF 2 TO 6 INCHES CONTINUES FOR THE PM.
THE HIGHER AMOUNTS OVER THE HIGHER TERRAIN...BASED ON THE 12Z
NAM...AND RUC TRENDS /FAVORS WRN NEW ENGLAND/. EXPECTING SNOW TO
LIQUID RATIOS OF 15-20:1 TO ACCOUNT FOR TOTALS TO GET INTO THE
ADVISORY RANGE.
THE 850-700HPA 2D FGEN BASED ON THE 12Z 40-KM NAM SHOWS A DECENT
RIBBON EXTENDING UP TO THE CAPITAL REGION AND DIPPING SOUTH AND
EAST. HENCE...AN ADDITIONAL 1 TO 4 INCHES OF SNOW MAY BE POSSIBLE.
SNOW TOTALS SO FAR HAVE RANGED FROM A HALF AN INCH TO TWO INCHES BASED
ON OUR LATEST PNS.
TEMPS TODAY WILL STRUGGLE TO CLIMB INTO AND THROUGH THE TEENS TO
LOWER 20S IN VALLEY AREAS...AND LOWER TO MID TEENS ACROSS HIGHER
ELEVATIONS...WITH MAX TEMPS LIKELY NOT OCCURRING UNTIL BETWEEN 5-7
PM. GIVEN THAT THE CLOUDS WILL BE RATHER LOW...AND THAT MUCH OF
THE PRECIP WILL BE FALLING FROM A LOWER CLOUD DECK INITIALLY THEN
WHAT OCCURRED ON SATURDAY...THE POTENTIAL AND DEPTH OF WET BULB
COOLING WILL BE LESS THAN WHAT OCCURRED THIS PAST SAT. SO...WE
HAVE SIDED WITH THE COOLER SIDE OF A MAV/MET MOS BLEND...BUT DID
NOT STRAY TOO MUCH.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH THURSDAY NIGHT/...
TONIGHT...ANY STEADIER SNOW SHOULD TAPER OFF ACROSS SE VT EARLY.
OTHERWISE...EXPECT SCATTERED SNOW SHOWERS TO OCCUR OVERNIGHT AS
THE MID/UPPER LEVEL TROPOSPHERIC TROUGH AND COLD POOL PASS
THROUGH...WITH 500 MB TEMPS DIPPING INTO THE -35C TO -40C RANGE.
925-700 LAPSE RATES STEEPEN...AND SHOULD ENOUGH MOISTURE BE
PRESENT WITHIN THIS LAYER...COULD LEAD TO SOME EMBEDDED HEAVIER SNOW
SHOWERS AND/OR SQUALLS...LEAVING ADDITIONAL COATINGS...TO PERHAPS
UP TO AN INCH OF SNOWFALL OVERNIGHT. TEMPS SHOULD FALL INTO THE
TEENS IN MOST AREAS.
WED-WED NT...THE AFOREMENTIONED MID LEVEL TROUGH/COLD POOL MOVES E
OF THE REGION IN THE AFTERNOON. HOWEVER...A FAIRLY WELL ALIGNED
WESTERLY FLOW MAY ALLOW FOR LAKE EFFECT SNOWBANDS TO DEVELOP
ACROSS NORTHERN HERKIMER CO IN THE AFTERNOON...AND MAY EXTEND WELL
INTO HAMILTON CO OR EVEN NW WARREN CO FOR A BRIEF TIME LATE IN THE
AFTERNOON INTO EARLY WED NT...AS SUGGESTED PER THE CSTAR FUNDED
INLAND LAKE EXTENT PROGRAM. THIS COULD LEAD TO AT LEAST 1-3 INCHES
OF SNOWFALL...WITH SOME POTENTIAL FOR GREATER AMTS...PERHAPS INTO
THE ADVISORY RANGE. WILL ADDRESS THIS POTENTIAL IN THE HWOALY.
ELSEWHERE...SCATTERED SNOW SHOWERS AND FLURRIES WILL BE POSSIBLE
ACROSS HIGHER ELEVATIONS...WHERE ADDITIONAL MINOR ACCUMS COULD
OCCUR...WITH SOME SNOW SHOWERS/FLURRIES OCCASIONALLY MIGRATING
INTO VALLEY AREAS...ESP NEAR AND N OF THE MOHAWK RIVER. FOR
TEMPS...EXPECT SLIGHTLY MILDER MAX TEMPS WED...REACHING THE 20S TO
LOWER 30S IN VALLEYS...WITH TEENS TO MID 20S ACROSS HIGHER
ELEVATIONS...AND OVERNIGHT MINS WED NT/THU AM FALLING MAINLY INTO
THE TEENS...WITH SOME SINGLE DIGITS POSSIBLE ACROSS NORTHERN AREAS
AND HIGHER ELEVATIONS ACROSS WESTERN NEW ENGLAND.
THU-THU NT...A SOUTHWEST LOW LEVEL FLOW WILL DEVELOP DURING THIS
TIME...ALLOWING FOR GRADUAL MODERATION IN TEMPS. SOME LINGERING
LAKE EFFECT SNOW MAY OCCUR THU ACROSS EXTREME NORTHERN
HERKIMER/HAMILTON COS...BEFORE THE INVERSION LEVEL FALLS.
THEN...SOME WARM ADVECTION PRECIP COULD DEVELOP ACROSS THE WESTERN
DACKS LATE THU NT...IN THE FORM OF LIGHT SNOW...OR EVEN A LIGHT
WINTRY MIX. THU MAX TEMPS SHOULD REACH THE LOWER/MID 30S IN
VALLEYS...AND 20S ACROSS HIGHER ELEVATIONS...WITH OVERNIGHT MINS
THU NT/FRI AM ONLY FALLING INTO THE 20S IN MOST AREAS...WITH TEMPS
POSSIBLY RISING IN SOME AREAS LATE AT NIGHT.
&&
.LONG TERM /FRIDAY THROUGH MONDAY/...
INCREASING AGREEMENT IN THE MODEL AND ENSEMBLE GUIDANCE THROUGH THE
PERIOD. ONE UPPER IMPULSE AND ASSOCIATED FORCING SUPPORTS
PRECIPITATION FRIDAY AND FRIDAY NIGHT. THEN ANOTHER UPPER IMPULSE
AND ASSOCIATED FORCING AFFECTS OUR REGION SATURDAY NIGHT THROUGH
SUNDAY NIGHT. THE TIMING OF THESE SYSTEMS WILL LIKELY GET ADJUSTED
WITH TIME AS THEY ARE WITHIN QUICK WEST SOUTHWEST UPPER CONFLUENT
STEERING FLOW. ALSO...WORDING RAIN AND SNOW THROUGH THE PERIOD SINCE
THERE IS SUCH HIGH UNCERTAINTY IN THE POTENTIAL AREAS OF SLEET
AND/OR FREEZING RAIN.
THE PRECIPITATION TYPES AND THE POSITION OF A POTENTIALLY BROAD
PRECIPITATION TRANSITION ZONE ARE STILL IN QUESTION. HOWEVER...
THERE IS MORE AGREEMENT FOR ANY MIXED PRECIPITATION EARLY FRIDAY
MORNING TO CHANGE TO MAINLY LIQUID PRECIPITATION OVER CENTRAL AND
SOUTHERN AREAS BEFORE COVERAGE OF PRECIPITATION DECREASES FRIDAY
NIGHT. MIXED PRECIPITATION COULD REMAIN MIXED OVER NORTHERN AREAS.
HIGHS FRIDAY IN THE LOWER TO MID 40S IN MANY AREAS WITH MID TO UPPER
30S IN THE HIGHER ELEVATIONS.
LOW LEVEL FORCING WEAKENS FRIDAY NIGHT AND SATURDAY WITH WEAK LOW
LEVEL RIDGING OVER THE REGION. LINGERING MOISTURE AND PROXIMITY TO
THE LOW LEVEL THERMAL GRADIENT AND WIND CONVERGENCE PROXIMATE TO THE
LOW LEVEL BOUNDARY COULD SUPPORT SCATTERED SHOWERS...WITH SOME
FLURRIES OR SNOW SHOWERS. THE BRIEF LOW LEVEL RIDGING COULD ALLOW
TEMPERATURES TO FALL TO NEAR FREEZING IN MANY AREAS FRIDAY NIGHT AND
MID TO UPPER 20S IN THE HIGHER ELEVATIONS... AGAIN SUPPORTING
SCATTERED SHOWERS AND SNOW SHOWERS.
CURRENT GUIDANCE SUGGESTS THE NEXT SYSTEM ARRIVES THROUGH THE DAY
SATURDAY AN CONTINUES SATURDAY NIGHT THROUGH SUNDAY...EXITING SUNDAY
NIGHT. THE WARM ADVECTION AND FORCING LOOK STRONGER WITH THIS
SYSTEM...DRIVING THE WARM AIR FURTHER NORTH...SUPPORTING A
PRECIPITATION TRANSITION TO RAIN IN MOST AREAS. QUITE A STRONG
SOUTHWEST TO WEST SOUTHWEST BOUNDARY LAYER JET TRACKS THROUGH THE
REGION AND THE BOUNDARY LAYER THERMAL GRADIENT IS QUITE TIGHT AS IT
TRACKS EAST AND SOUTH SUNDAY AND SUNDAY NIGHT. SO...WILL HAVE TO
KEEP AN EYE ON WINDS AND POTENTIAL FOR LOCALLY HEAVY RAIN ON THE
MELTING SNOW PACK. HIGHS SATURDAY IN THE LOWER TO MID 40S...LOWER
TO MID 30S HIGHER ELEVATIONS. HIGHS SUNDAY IN THE UPPER 40S TO LOWER
50S...WITH UPPER 30S TO LOWER 40S IN HIGHER ELEVATIONS.
STRONG COLD ADVECTION SPREADS ACROSS THE REGION BY MONDAY MORNING
AND CONTINUES THROUGH THE DAY. SOME LAKE EFFECT SNOW BANDS SHOULD
FORM BUT INLAND EXTENT IS IN QUESTION. HIGHS MONDAY IN THE 20S TO
LOWER 30S.
THERE COULD STILL BE A LOT OF CHANGES TO HOW THESE SYSTEMS DEVELOP
AND IMPACT THE REGION. THERE ARE INDICATIONS OF A POTENTIAL BROAD
MIXED PRECIPITATION TRANSITION ZONE...BUT THE POSITION AND AREAL
EXTENT OF THE PRECIPITATION TRANSITION ZONE KEEPS CHANGING IN
SUCCESSIVE SETS OF GUIDANCE. THERE IS STILL A CHANCE THAT THE
CURRENT INDICATIONS OF MORE RAIN AND LESS WINTERY PRECIPITATION OVER
MUCH OF OUR REGION COULD CHANGE BACK TO COLDER AND MORE MIXED
PRECIPITATION DEPENDING ON HOW THE SYSTEMS DEVELOP IN THE NEXT 3+
DAYS. HOWEVER...THE INCREASING CONSENSUS FROM GUIDANCE OF MORE
LIQUID AND LESS MIXED PRECIPITATION SEEMS THE MOST LIKELY SCENARIO
AT THIS TIME.
&&
.AVIATION /18Z TUESDAY THROUGH SUNDAY/...
COASTAL WAVE WAS TAKING SHAPE AS ANY BRIEF LULL IN THE SNOW IS
EXPECTED TO FULL BACK IN THIS AFTERNOON. THIS WILL KEEP FLIGHT
CONDITIONS WITHIN MVFR AND TEMPORARILY IFR CONDITIONS AS THESE BANDS
OF MODERATE SNOWFALL DEVELOP AND IMPACT THE TAF SITES. PER THE
LATEST GUIDANCE AND UPSTREAM INFORMATION...SEEMS THIS SNOW WILL EXIT
THE REGION BY EARLY THIS EVENING WITH IMPROVEMENTS.
HOWEVER...FLIGHT CONDITIONS WILL REMAIN WITHIN MVFR THRESHOLDS WITH
SOME IFR EXPECTED AT KPOU OVERNIGHT.
WINDS ARE EXPECTED TO REMAIN RATHER LIGHT WITH A GENERALLY NORTH
DIRECTION. THE MAGNITUDES ARE EXPECTED TO DIMINISH FURTHER THIS
EVENING WITH A WEST-NORTHWEST DIRECTION DEVELOPING THROUGH
WEDNESDAY.
OUTLOOK...
WEDNESDAY NIGHT: NO OPERATIONAL IMPACT. NO SIG WX.
THURSDAY: NO OPERATIONAL IMPACT. NO SIG WX.
THURSDAY NIGHT: LOW OPERATIONAL IMPACT. SLIGHT CHANCE OF SHSN.
FRIDAY: MODERATE OPERATIONAL IMPACT. CHANCE OF RA...SN.
FRIDAY NIGHT: MODERATE OPERATIONAL IMPACT. SCATTERED SHRA...SHSN.
SATURDAY: MODERATE OPERATIONAL IMPACT. CHANCE OF RA...SN.
&&
.HYDROLOGY...
A CLIPPER TYPE SYSTEM WILL AFFECT THE REGION TODAY INTO THIS
EVENING. THE PRECIPITATION IS EXPECTED TO BE ALL SNOW WITH THIS
SYSTEM. TOTAL LIQUID EQUIVALENT WITH THIS SYSTEM IS EXPECTED TO
RANGE FROM ONE TO THREE TENTHS OF AN INCH WITH THE HIGHEST AMOUNTS
OVER THE ERN CATSKILLS...W-CNTRL MOHAWK VALLEY...AND WRN NEW
ENGLAND. THIS SYSTEM WILL REDEVELOP SOUTH OF LONG ISLAND...AND
QUICKLY MOVE NORTHEAST OF CAPE COD TOMORROW NIGHT.
SOME LAKE EFFECT SNOW IS POSSIBLE WED-THU WITH LIGHT SNOW
AMOUNTS...AND LIQUID EQUIVALENTS GENERALLY LESS THAN A TENTH OF AN
INCH FOR THE WRN DACKS REGION...AND NRN TIER OF THE HSA.
FOR THE MID WEEK...TEMPS WILL CONTINUE TO BE BELOW NORMAL AND ICE
WILL CONTINUE TO FORM AND THICKEN ON AREA RIVERS...STREAMS AND
PARTICULARLY LAKES.
A MODERATING TREND IN TEMPS IS LIKELY THU INTO FRI...WITH A
FRONTAL BOUNDARY BRINGING SOME SHOWERS TO CLOSE THE WORK WEEK.
SOME SNOW MELT IS LIKELY THIS WEEKEND. ALSO...A STORM SYSTEM
MOVING ALONG A FRONTAL BOUNDARY NEAR THE HSA MAY BRING SIGNIFICANT
PCPN TO THE FORECAST AREA SAT NIGHT INTO SUNDAY WITH EVEN MILDER
TEMPS. THIS WILL CONTINUE TO BE MONITORED FOR THE UPCOMING
WEEKEND.
FOR DETAILS ON SPECIFIC AREA RIVERS AND LAKES...INCLUDING OBSERVED
AND FORECAST RIVER STAGES AND LAKE ELEVATIONS...PLEASE VISIT THE
ADVANCED HYDROLOGIC PREDICTION SERVICE /AHPS/ GRAPHS ON OUR WEBSITE.
&&
.ALY WATCHES/WARNINGS/ADVISORIES...
CT...WINTER WEATHER ADVISORY UNTIL 7 PM EST THIS EVENING FOR CTZ001-
013.
NY...WINTER WEATHER ADVISORY UNTIL 7 PM EST THIS EVENING FOR
NYZ038>040-047>054-058>061-063>066-082.
MA...WINTER WEATHER ADVISORY UNTIL 7 PM EST THIS EVENING FOR MAZ001-
025.
VT...WINTER WEATHER ADVISORY UNTIL 7 PM EST THIS EVENING FOR
VTZ013>015.
&&
$$
SYNOPSIS...KL/WASULA
NEAR TERM...KL/BGM/WASULA
SHORT TERM...KL
LONG TERM...NAS
AVIATION...BGM
HYDROLOGY...KL/WASULA
AREA FORECAST DISCUSSION
NWS ALBANY NY
1040 AM EST TUE DEC 17 2013
.SYNOPSIS...
A LOW PRESSURE SYSTEM PASSING SOUTH OF THE REGION WILL BRING A
WIDESPREAD LIGHT TO MODERATE SNOWFALL TO THE AREA TODAY. THE SNOW
WILL SPREAD NORTHWARD ACROSS THE AREA DURING THIS MORNING AND IS
EXPECTED TO TAPER OFF THIS EVENING. SCATTERED SNOW SHOWERS ARE
THEN EXPECTED TONIGHT AND WEDNESDAY...ESPECIALLY ACROSS THE HIGHER
TERRAIN. A GRADUAL WARMING TREND IS THEN EXPECTED FOR THE END OF
THE WORKWEEK.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
AS OF 1040 AM EST...UPDATED THE WINTER WX ADVISORY TO INCLUDE THE
CAPITAL REGION...MOHAWK RIVER VALLEY...SCHOHARIE VALLEY...AND
HELDERBERGS. SNOWFALL POTENTIAL OF 2 TO 6 INCHES HERE BASED ON THE
LATEST RADAR...12Z NAM...AND RUC TRENDS. EXPECTING SNOW TO LIQUID
RATIOS OF 15-20:1 TO ACCOUNT FOR TOTALS TO GET INTO THE ADVISORY
RANGE. THE KENX AND KBGM RADARS INDICATING SOME BANDLETS OR MINI
BANDS WITH SNOW RATES APPROACHING A HALF AN INCH TO AN INCH AND
HOUR. THE ADVISORY WILL ALSO GO TO 00Z/7 PM EST.
SNOW HAS BEEN RAPIDLY EXPANDING NORTHWARD ACROSS THE REGION WITH
RECENT RADAR TRENDS INDICATING MODERATE BANDS MOVING NORTHWARD. A
FEW BREAKS ACROSS THE MID HUDSON VALLEY HAVE OCCURRED BUT SHOULD
FILL BACK IN AS SURFACE LOW DEVELOPS JUST OFF THE NJ COAST.
850-700HPA 2D FGEN PER THE RUC13/HRRR INDICATES A BAND OF MODERATE
SNOW SHOULD DEVELOP EITHER ALONG OR SOUTH OF I90 LATE THIS
AFTERNOON AS WE WILL LEAVE THE CURRENT HEADLINES IN PLACE. WE ARE
EXPECTING THE SNOW TO LIQUID RATIOS TO DROP CLOSER TO 15:1 IN THE
STRONG WARM ADVECTION REGIME...AND WITH THE SECONDARY LOW PRESSURE
DEVELOPMENT OCCURRING NEAR SE NJ AT THIS TIME.
TEMPS TODAY WILL STRUGGLE TO CLIMB INTO AND THROUGH THE TEENS TO
LOWER 20S IN VALLEY AREAS...AND LOWER TO MID TEENS ACROSS HIGHER
ELEVATIONS...WITH MAX TEMPS LIKELY NOT OCCURRING UNTIL BETWEEN 5-7
PM. GIVEN THAT THE CLOUDS WILL BE RATHER LOW...AND THAT MUCH OF
THE PRECIP WILL BE FALLING FROM A LOWER CLOUD DECK INITIALLY THEN
WHAT OCCURRED ON SATURDAY...THE POTENTIAL AND DEPTH OF WET BULB
COOLING WILL BE LESS THAN WHAT OCCURRED THIS PAST SAT. SO...WE
HAVE SIDED WITH THE COOLER SIDE OF A MAV/MET MOS BLEND...BUT DID
NOT STRAY TOO MUCH.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH THURSDAY NIGHT/...
TONIGHT...ANY STEADIER SNOW SHOULD TAPER OFF ACROSS SE VT EARLY.
OTHERWISE...EXPECT SCATTERED SNOW SHOWERS TO OCCUR OVERNIGHT AS
THE MID/UPPER LEVEL TROPOSPHERIC TROUGH AND COLD POOL PASS
THROUGH...WITH 500 MB TEMPS DIPPING INTO THE -35C TO -40C RANGE.
925-700 LAPSE RATES STEEPEN...AND SHOULD ENOUGH MOISTURE BE
PRESENT WITHIN THIS LAYER...COULD LEAD TO SOME EMBEDDED HEAVIER SNOW
SHOWERS AND/OR SQUALLS...LEAVING ADDITIONAL COATINGS...TO PERHAPS
UP TO AN INCH OF SNOWFALL OVERNIGHT. TEMPS SHOULD FALL INTO THE
TEENS IN MOST AREAS.
WED-WED NT...THE AFOREMENTIONED MID LEVEL TROUGH/COLD POOL MOVES E
OF THE REGION IN THE AFTERNOON. HOWEVER...A FAIRLY WELL ALIGNED
WESTERLY FLOW MAY ALLOW FOR LAKE EFFECT SNOWBANDS TO DEVELOP
ACROSS NORTHERN HERKIMER CO IN THE AFTERNOON...AND MAY EXTEND WELL
INTO HAMILTON CO OR EVEN NW WARREN CO FOR A BRIEF TIME LATE IN THE
AFTERNOON INTO EARLY WED NT...AS SUGGESTED PER THE CSTAR FUNDED
INLAND LAKE EXTENT PROGRAM. THIS COULD LEAD TO AT LEAST 1-3 INCHES
OF SNOWFALL...WITH SOME POTENTIAL FOR GREATER AMTS...PERHAPS INTO
THE ADVISORY RANGE. WILL ADDRESS THIS POTENTIAL IN THE HWOALY.
ELSEWHERE...SCATTERED SNOW SHOWERS AND FLURRIES WILL BE POSSIBLE
ACROSS HIGHER ELEVATIONS...WHERE ADDITIONAL MINOR ACCUMS COULD
OCCUR...WITH SOME SNOW SHOWERS/FLURRIES OCCASIONALLY MIGRATING
INTO VALLEY AREAS...ESP NEAR AND N OF THE MOHAWK RIVER. FOR
TEMPS...EXPECT SLIGHTLY MILDER MAX TEMPS WED...REACHING THE 20S TO
LOWER 30S IN VALLEYS...WITH TEENS TO MID 20S ACROSS HIGHER
ELEVATIONS...AND OVERNIGHT MINS WED NT/THU AM FALLING MAINLY INTO
THE TEENS...WITH SOME SINGLE DIGITS POSSIBLE ACROSS NORTHERN AREAS
AND HIGHER ELEVATIONS ACROSS WESTERN NEW ENGLAND.
THU-THU NT...A SOUTHWEST LOW LEVEL FLOW WILL DEVELOP DURING THIS
TIME...ALLOWING FOR GRADUAL MODERATION IN TEMPS. SOME LINGERING
LAKE EFFECT SNOW MAY OCCUR THU ACROSS EXTREME NORTHERN
HERKIMER/HAMILTON COS...BEFORE THE INVERSION LEVEL FALLS.
THEN...SOME WARM ADVECTION PRECIP COULD DEVELOP ACROSS THE WESTERN
DACKS LATE THU NT...IN THE FORM OF LIGHT SNOW...OR EVEN A LIGHT
WINTRY MIX. THU MAX TEMPS SHOULD REACH THE LOWER/MID 30S IN
VALLEYS...AND 20S ACROSS HIGHER ELEVATIONS...WITH OVERNIGHT MINS
THU NT/FRI AM ONLY FALLING INTO THE 20S IN MOST AREAS...WITH TEMPS
POSSIBLY RISING IN SOME AREAS LATE AT NIGHT.
&&
.LONG TERM /FRIDAY THROUGH MONDAY/...
INCREASING AGREEMENT IN THE MODEL AND ENSEMBLE GUIDANCE THROUGH THE
PERIOD. ONE UPPER IMPULSE AND ASSOCIATED FORCING SUPPORTS
PRECIPITATION FRIDAY AND FRIDAY NIGHT. THEN ANOTHER UPPER IMPULSE
AND ASSOCIATED FORCING AFFECTS OUR REGION SATURDAY NIGHT THROUGH
SUNDAY NIGHT. THE TIMING OF THESE SYSTEMS WILL LIKELY GET ADJUSTED
WITH TIME AS THEY ARE WITHIN QUICK WEST SOUTHWEST UPPER CONFLUENT
STEERING FLOW. ALSO...WORDING RAIN AND SNOW THROUGH THE PERIOD SINCE
THERE IS SUCH HIGH UNCERTAINTY IN THE POTENTIAL AREAS OF SLEET
AND/OR FREEZING RAIN.
THE PRECIPITATION TYPES AND THE POSITION OF A POTENTIALLY BROAD
PRECIPITATION TRANSITION ZONE ARE STILL IN QUESTION. HOWEVER...
THERE IS MORE AGREEMENT FOR ANY MIXED PRECIPITATION EARLY FRIDAY
MORNING TO CHANGE TO MAINLY LIQUID PRECIPITATION OVER CENTRAL AND
SOUTHERN AREAS BEFORE COVERAGE OF PRECIPITATION DECREASES FRIDAY
NIGHT. MIXED PRECIPITATION COULD REMAIN MIXED OVER NORTHERN AREAS.
HIGHS FRIDAY IN THE LOWER TO MID 40S IN MANY AREAS WITH MID TO UPPER
30S IN THE HIGHER ELEVATIONS.
LOW LEVEL FORCING WEAKENS FRIDAY NIGHT AND SATURDAY WITH WEAK LOW
LEVEL RIDGING OVER THE REGION. LINGERING MOISTURE AND PROXIMITY TO
THE LOW LEVEL THERMAL GRADIENT AND WIND CONVERGENCE PROXIMATE TO THE
LOW LEVEL BOUNDARY COULD SUPPORT SCATTERED SHOWERS...WITH SOME
FLURRIES OR SNOW SHOWERS. THE BRIEF LOW LEVEL RIDGING COULD ALLOW
TEMPERATURES TO FALL TO NEAR FREEZING IN MANY AREAS FRIDAY NIGHT AND
MID TO UPPER 20S IN THE HIGHER ELEVATIONS... AGAIN SUPPORTING
SCATTERED SHOWERS AND SNOW SHOWERS.
CURRENT GUIDANCE SUGGESTS THE NEXT SYSTEM ARRIVES THROUGH THE DAY
SATURDAY AN CONTINUES SATURDAY NIGHT THROUGH SUNDAY...EXITING SUNDAY
NIGHT. THE WARM ADVECTION AND FORCING LOOK STRONGER WITH THIS
SYSTEM...DRIVING THE WARM AIR FURTHER NORTH...SUPPORTING A
PRECIPITATION TRANSITION TO RAIN IN MOST AREAS. QUITE A STRONG
SOUTHWEST TO WEST SOUTHWEST BOUNDARY LAYER JET TRACKS THROUGH THE
REGION AND THE BOUNDARY LAYER THERMAL GRADIENT IS QUITE TIGHT AS IT
TRACKS EAST AND SOUTH SUNDAY AND SUNDAY NIGHT. SO...WILL HAVE TO
KEEP AN EYE ON WINDS AND POTENTIAL FOR LOCALLY HEAVY RAIN ON THE
MELTING SNOW PACK. HIGHS SATURDAY IN THE LOWER TO MID 40S...LOWER
TO MID 30S HIGHER ELEVATIONS. HIGHS SUNDAY IN THE UPPER 40S TO LOWER
50S...WITH UPPER 30S TO LOWER 40S IN HIGHER ELEVATIONS.
STRONG COLD ADVECTION SPREADS ACROSS THE REGION BY MONDAY MORNING
AND CONTINUES THROUGH THE DAY. SOME LAKE EFFECT SNOW BANDS SHOULD
FORM BUT INLAND EXTENT IS IN QUESTION. HIGHS MONDAY IN THE 20S TO
LOWER 30S.
THERE COULD STILL BE A LOT OF CHANGES TO HOW THESE SYSTEMS DEVELOP
AND IMPACT THE REGION. THERE ARE INDICATIONS OF A POTENTIAL BROAD
MIXED PRECIPITATION TRANSITION ZONE...BUT THE POSITION AND AREAL
EXTENT OF THE PRECIPITATION TRANSITION ZONE KEEPS CHANGING IN
SUCCESSIVE SETS OF GUIDANCE. THERE IS STILL A CHANCE THAT THE
CURRENT INDICATIONS OF MORE RAIN AND LESS WINTERY PRECIPITATION OVER
MUCH OF OUR REGION COULD CHANGE BACK TO COLDER AND MORE MIXED
PRECIPITATION DEPENDING ON HOW THE SYSTEMS DEVELOP IN THE NEXT 3+
DAYS. HOWEVER...THE INCREASING CONSENSUS FROM GUIDANCE OF MORE
LIQUID AND LESS MIXED PRECIPITATION SEEMS THE MOST LIKELY SCENARIO
AT THIS TIME.
&&
.AVIATION /16Z TUESDAY THROUGH SATURDAY/...
A LOW PRESSURE SYSTEM WILL BRING A WIDESPREAD LIGHT TO MODERATE
SNOWFALL TO THE AREA TODAY. THE SNOW WILL SPREAD NORTHWARD ACROSS
THE AREA DURING THE MORNING AND IS EXPECTED TO TAPER OFF TOWARD THIS
EVENING.
SNOW IS BEGINNING AT KPOU AND WILL SPREAD NORTHWARD TO KALB AND KPSF
BY 13Z-14Z AND BY KGFL BY 14Z. INITIALLY MVFR CONDITIONS ARE
EXPECTED WITH IFR DEVELOPING AS THE SNOW BECOMES STEADIER AS THE
MORNING PROGRESSES. AROUND 5 HOURS OF IFR SNOWS ARE EXPECTED WITH AN
IMPROVE BACK TO MVFR MID TO LATE AFTERNOON. KEEPING VCSH THROUGH
ABOUT 05Z AT ALL TAF SITES WITH LINGERING MOISTURE. AFTER
05Z-06Z...VFR CEILINGS AND VISIBILITIES SHOULD PREVAIL AT ALL TAF
SITES.
WINDS WILL BE NEARLY CALM THROUGH THE MORNING HOURS WITH A LIGHT
SOUTHEASTERLY FLOW DEVELOPING LATER IN THE MORNING AND BECOMING
VARIABLE AGAIN BY LATE AFTERNOON AND EVENING.
OUTLOOK...
WEDNESDAY NIGHT: NO OPERATIONAL IMPACT. NO SIG WX.
THURSDAY: NO OPERATIONAL IMPACT. NO SIG WX.
THURSDAY NIGHT: LOW OPERATIONAL IMPACT. SLIGHT CHANCE OF SHSN.
FRIDAY: MODERATE OPERATIONAL IMPACT. CHANCE OF RA...SN.
FRIDAY NIGHT: MODERATE OPERATIONAL IMPACT. SCATTERED SHRA...SHSN.
SATURDAY: MODERATE OPERATIONAL IMPACT. CHANCE OF RA...SN.
&&
.HYDROLOGY...
A CLIPPER TYPE SYSTEM WILL AFFECT THE REGION TODAY INTO THIS
EVENING. THE PRECIPITATION IS EXPECTED TO BE ALL SNOW WITH THIS
SYSTEM. TOTAL LIQUID EQUIVALENT WITH THIS SYSTEM IS EXPECTED TO
RANGE FROM ONE TO THREE TENTHS OF AN INCH WITH THE HIGHEST AMOUNTS
OVER THE ERN CATSKILLS...W-CNTRL MOHAWK VALLEY...AND WRN NEW
ENGLAND. THIS SYSTEM WILL REDEVELOP SOUTH OF LONG ISLAND...AND
QUICKLY MOVE NORTHEAST OF CAPE COD TOMORROW NIGHT.
SOME LAKE EFFECT SNOW IS POSSIBLE WED-THU WITH LIGHT SNOW
AMOUNTS...AND LIQUID EQUIVALENTS GENERALLY LESS THAN A TENTH OF AN
INCH FOR THE WRN DACKS REGION...AND NRN TIER OF THE HSA.
FOR THE MID WEEK...TEMPS WILL CONTINUE TO BE BELOW NORMAL AND ICE
WILL CONTINUE TO FORM AND THICKEN ON AREA RIVERS...STREAMS AND
PARTICULARLY LAKES.
A MODERATING TREND IN TEMPS IS LIKELY THU INTO FRI...WITH A
FRONTAL BOUNDARY BRINGING SOME SHOWERS TO CLOSE THE WORK WEEK.
SOME SNOW MELT IS LIKELY THIS WEEKEND. ALSO...A STORM SYSTEM
MOVING ALONG A FRONTAL BOUNDARY NEAR THE HSA MAY BRING SIGNIFICANT
PCPN TO THE FORECAST AREA SAT NIGHT INTO SUNDAY WITH EVEN MILDER
TEMPS. THIS WILL CONTINUE TO BE MONITORED FOR THE UPCOMING
WEEKEND.
FOR DETAILS ON SPECIFIC AREA RIVERS AND LAKES...INCLUDING OBSERVED
AND FORECAST RIVER STAGES AND LAKE ELEVATIONS...PLEASE VISIT THE
ADVANCED HYDROLOGIC PREDICTION SERVICE /AHPS/ GRAPHS ON OUR WEBSITE.
&&
.ALY WATCHES/WARNINGS/ADVISORIES...
CT...WINTER WEATHER ADVISORY UNTIL 7 PM EST THIS EVENING FOR CTZ001-
013.
NY...WINTER WEATHER ADVISORY UNTIL 7 PM EST THIS EVENING FOR
NYZ038>040-047>054-058>061-063>066-082.
MA...WINTER WEATHER ADVISORY UNTIL 7 PM EST THIS EVENING FOR MAZ001-
025.
VT...WINTER WEATHER ADVISORY UNTIL 7 PM EST THIS EVENING FOR
VTZ013>015.
&&
$$
SYNOPSIS...KL/WASULA
NEAR TERM...KL/BGM/WASULA
SHORT TERM...KL
LONG TERM...NAS
AVIATION...NAS
HYDROLOGY...KL/WASULA
AREA FORECAST DISCUSSION
NWS TAUNTON MA
702 AM EST TUE DEC 17 2013
.SYNOPSIS...
A FAST MOVING LOW PRESSURE SYSTEM WILL BRING ACCUMULATING SNOW TO
THE REGION TODAY. DRY BUT CHILLY AND BLUSTERY WEATHER FOLLOWS WED
BEHIND THE DEPARTING LOW. SOMEWHAT MILDER WEATHER ARRIVES THU AND
FRI WITH THE POTENTIAL FOR UNSETTLED WEATHER THIS WEEKEND.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
7 AM UPDATE...BIG STORY AT THIS TIME IS THE COLD TEMPERATURES.
ASIDE FROM THE SOUTH COAST AND THE LARGER CITIES...TEMPERATURES
ARE IN THE SINGLE DIGITS BOTH ABOVE AND BELOW ZERO. HOWEVER...THE
FOCUS WILL TURN QUICKLY TO THE APPROACHING SNOW. THE LEADING EDGE
OF THE SNOW HAS WORKED ITS WAY INTO SOUTHWESTERN CONNECTICUT.
WHILE DEWPOINTS ARE VERY LOW THIS MORNING...THEY HAVE BEEN RISING
QUICKLY AS THE SNOW MOVES IN. STILL ANTICIPATING SNOW TO ARRIVE IN
THE HARTFORD METRO AREA ABOUT 8 AM...WORCESTER AND PROVIDENCE
AROUND 10 AM AND BOSTON METRO AROUND 11 AM.
MADE SOME EDITS TO THE TEMPERATURES AND DEWPOINTS TO BRING THEM
MORE IN LINE WITH CURRENT TRENDS. HIGH RESOLUTION NEAR TERM MODELS
ARE STRUGGLING WITH THE COLD BUT THE HRRR FINALLY CAUGHT UP TO THE
TEMPERATURES...SO USED THAT TO ADJUST THE TEMPS. OTHERWISE...THE
FORECAST IS ON TRACK.
PREVIOUS DISCUSSION...
AS FOR THE REST OF TODAY...VERY TRICKY FORECAST FOR SNOW
ACCUMULATIONS DESPITE VERY COLD TEMPERATURES TO START. 17/00Z GFS
APPEARS TO BE A SLOWER AND STRONGER OUTLIER SOLUTION. WILL STICK
WITH THE CONSENSUS TIMING OF THE OTHER GUIDANCE. THIS WOULD TAKE A
FAST-MOVING LOW PRESSURE FROM THE MID ATLANTIC COAST THIS
MORNING...ACROSS CAPE COD AND THE ISLANDS THIS EVENING.
THIS TRACK WILL COMPLICATE SNOW ACCUMULATIONS ACROSS SOUTHEAST MA
AND SOUTHERN RI AS ONSHORE FLOW OVER 45F-50F WATER WILL RESULT IN
AT LEAST SOME WARMING IN THE LOW LEVELS. UNLIKE THE STORM THIS
PAST WEEKEND...THINKING MIXING ZONE WILL STAY CLOSER TO THE COAST
AS THIS LOW PRESSURE SHOULD REMAIN WEAKER.
AT THIS TIME WATCHING LIGHT SNOW BREAK OUT ACROSS CENTRAL AND
NORTHEAST PA. THIS COULD PUT SOME SNOW INTO SOUTHERN NEW ENGLAND
FOR THE MORNING COMMUTE...BUT VISIBILITY SHOULD NOT BE BAD. THE
HARTFORD-SPRINGFIELD METRO AREA WOULD BE MOST AFFECTED. THE
AFTERNOON/EVENING COMMUTE WILL BE MORE PROBLEMATIC WITH POOR
VISIBILITY AND SLIPPERY TRAVEL. PLEASE KEEP THIS IN MIND WHEN
PLANNING YOUR DAY.
THERE IS SOME POTENTIAL FOR CONVECTIVE BANDING...MAINLY ACROSS
NORTH CENTRAL AND NORTHEAST MA INTO SOUTHERN NH. ENHANCEMENT IN
THIS AREA IS MORE LIKELY AS WELL WITH ONSHORE FLOW PRODUCING AN
OCEAN EFFECT CONTRIBUTION. THERE COULD BE OTHER AREAS OF
CONVECTIVE ENHANCEMENT...BUT DO NOT HAVE AS HIGH A CONFIDENCE AS
THE MERRIMACK VALLEY. THINKING MOST AREAS WILL SEE AROUND 4 INCHES
OF SNOWFALL ACROSS THE INTERIOR WITH LOCALLY HIGHER AMOUNTS WHEN
ALL IS DONE.
DECIDED THE END TIMING OF THE WINTER WEATHER ADVISORIES WAS TOO
CLOSE FOR COMFORT. EXTENDED THE ADVISORY FOR THE WESTERN HALF OF
SOUTHERN NEW ENGLAND AND SOUTHEAST MA AND RI TO COVER MORE OF THE
EVENING COMMUTE. ALSO EXTENDED THE ADVISORY FOR SOUTHERN NH AND
NORTHEAST MA...WITH THE THOUGHT OF A LONGER PERIOD OF SNOW IN THE
MERRIMACK VALLEY.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH 6 PM WEDNESDAY/...
PRECIPITATION WILL TAPER OFF FROM SOUTHWEST TO NORTHEAST LATE THIS
AFTERNOON INTO THIS EVENING. THE SKY CLEARING MAY TAKE A WHILE
LONGER AS THIS LOW PRESSURE DEVELOPS IN THE GULF OF MAINE AND
SENDS MORE CLOUDS BACK IN OUR DIRECTION. THINKING ONSHORE WINDS
WILL ALSO GENERATE SOME OCEAN-EFFECT SNOW BANDS...SO KEPT A CHANCE
OF SNOW ACROSS THE EASTERN HALF OF SOUTHERN NEW ENGLAND THROUGH
LATE TONIGHT.
BRISK WEST TO NORTHWEST WINDS WEDNESDAY SHOULD HELP PROVIDE
CLEARING WEDNESDAY...ALONG WITH DRIER WEATHER FOR THE AFTERNOON.
&&
.LONG TERM /WEDNESDAY NIGHT THROUGH MONDAY/...
HIGHLIGHTS...
* MILDER TEMPERATURES THU AND FRI
* UNSETTLED WEATHER OVER THE WEEKEND
MODELS ARE STRUGGLING WITH THE EVENTUAL EVOLUTION OF THE SPLIT FLOW
REGIME OVER THE EAST COAST. HAVE OPTED TO GO WITH A MORE WPC
SOLUTION...WHICH INCORPORATES ALL OF THE ENSEMBLE MEANS.
WEDNESDAY NIGHT THROUGH FRIDAY...SOUTHWESTERLY SURFACE WINDS WILL
DRAW WARMER AIR INTO THE REGION...RESULTING IN DAYTIME TEMPERATURES
WARMING THROUGH THIS PERIOD. WILL START TO SEE TEMPERATURES CLOSER
TO AVERAGE FOR MID DECEMBER INSTEAD OF THE 5-10 DEGREES BELOW NORMAL
WE HAVE HAD LATELY. THERE ARE DIFFERENCES IN HOW THE MODELS HANDLE
LOW PRESSURE MOVING THROUGH THE GREAT LAKES AND THE COLD FRONT
EXTENDING SOUTHWESTWARD FROM IT WHICH MAY AFFECT THE FORECAST FOR
THIS TIME FRAME. RIGHT NOW...AM FORECASTING THE FRONT TO MOVE INTO
SOUTHERN NEW ENGLAND EARLY SATURDAY.
SATURDAY THROUGH MONDAY...LOW PRESSURE MOVING INTO THE MARITIMES
WILL PULL A COLD FRONT THROUGH SOUTHERN NEW ENGLAND EARLY SATURDAY.
THIS FRONT THEN APPEARS TO STALL WHILE WAVES OF LOW PRESSURE MOVE
ALONG IT. THIS WILL RESULT IN SOME VERY UNSETTLED WEATHER OVER THE
WEEKEND. IT LOOKS LIKELY THAT SOME FORM OF PRECIPITATION WILL OCCUR
OVER MUCH OF THE REGION. UNFORTUNATELY TEMPERATURE PROFILES ARE
SUCH THAT SMALL SHIFTS WILL MAKE A BIG DIFFERENCE IN PRECIPITATION
TYPE. AT THIS TIME...IT LOOKS LIKE MUCH OF SATURDAY WILL BE
WARM...WITH TEMPERATURES ABOVE FREEZING THROUGH THE PROFILE DURING
THE DAY. THIS WOULD LEAD TO RAIN DURING THE DAY. AT NIGHT...A
WINTRY MIX IS POSSIBLE. THIS IS FURTHER COMPLICATED BY STRONG HIGH
PRESSURE IN SOUTHERN CANADA...WHICH COULD RESULT IN SOME COLD AIR
DRAINAGE. IN THIS CASE...TEMPERATURES AT THE SURFACE COULD BE BELOW
FREEZING WHILE THE THERMAL PROFILE REMAINS FAVORABLE FOR
RAIN...LEADING TO FREEZING RAIN. THERE IS A LOT OF UNCERTAINTY
RIGHT NOW...PARTICULARLY FOR THE WEEKEND. BELIEVE THE FRONT WILL
FINALLY MOVE OFFSHORE FOR MONDAY...ALLOWING HIGH PRESSURE TO BUILD
INTO THE REGION.
&&
.AVIATION /12Z TUESDAY THROUGH SATURDAY/...
FORECASTER CONFIDENCE LEVELS...
LOW...LESS THAN 30 PERCENT.
MODERATE...30 TO 60 PERCENT.
HIGH...GREATER THAN 60 PERCENT.
NEAR TERM /THROUGH WEDNESDAY/...HIGH CONFIDENCE IN TRENDS. LOWER
CONFIDENCE IN TIMING OF IFR CONDITIONS IN SNOW.
TODAY...CONDITIONS LOWERING TO MVFR-IFR FROM SW TO NE THIS MORNING
AS SNOW OVERSPREADS THE REGION. AREAS OF IFR THIS AFTERNOON WITH
LOCALLY HEAVY SNOW AT TIMES. SNOW ACCUM 3-5 INCHES POSSIBLE ALL
TERMINALS...LESS KFMH/KHYA/KACK WHERE SNOW WILL MIX WITH OR CHANGE
TO RAIN LATER TODAY.
TONIGHT...SNOW WILL LIKELY LINGER INTO THIS EVENING ACROSS
EASTERN MA WITH SOME SNOW SHOWERS POSSIBLE ELSEWHERE.
WEDNESDAY...IMPROVEMENT TO VFR FROM WEST TO EAST...MUCH MORE
RAPIDLY ACROSS THE INTERIOR THAN TOWARD THE EAST COAST OF MA.
KBOS TAF...HIGH CONFIDENCE IN DETERIORATING CONDITIONS BY MIDDAY
AS SNOW MOVES IN. EXACT TIMING MAY BE OFF A FEW HOURS.
KBDL TAF...HIGH CONFIDENCE IN DETERIORATING CONDITIONS THIS
MORNING AS SNOW MOVES IN. EXACT TIMING MAY BE OFF A FEW HOURS.
OUTLOOK...WEDNESDAY NIGHT THROUGH SATURDAY...
WEDNESDAY NIGHT THROUGH THURSDAY...HIGH CONFIDENCE. VFR.
FRIDAY...MODERATE CONFIDENCE. MAINLY VFR. MVFR/IFR CONDITIONS
DEVELOP LATE FRIDAY NIGHT IN FOG AND LOW CLOUDS.
SATURDAY...LOW CONFIDENCE. MVFR/IFR CONDITIONS LIKELY IN POSSIBLY A
WINTRY MIX OF PRECIPITATION.
&&
.MARINE...
FORECASTER CONFIDENCE LEVELS...
LOW...LESS THAN 30 PERCENT.
MODERATE...30 TO 60 PERCENT.
HIGH...GREATER THAN 60 PERCENT.
NEAR TERM /THROUGH WEDNESDAY/...HIGH CONFIDENCE.
ANOTHER ROUND OF EASTERLY SCA WIND GUSTS TO 25-30 KT LIKELY THIS
AFTERNOON INTO THIS EVENING...ESPECIALLY OUTER WATERS ASSOCIATED
WITH A COASTAL STORM. REDUCED VSBYS THIS AFTERNOON AND EVENING IN
RAIN AND SNOW. WILL REEVALUATE NEED TO ISSUE NEW SMALL CRAFT
ADVISORIES SOON.
WEDNESDAY...HIGH CONFIDENCE. WEST TO NORTHWEST SCA WIND GUSTS OF 25
TO 30 KTS EXPECTED WITH COLD ADVECTION OVER THE RELATIVELY MILD
OCEAN.
OUTLOOK...WEDNESDAY NIGHT THROUGH SATURDAY...
WEDNESDAY NIGHT AND THURSDAY...MODERATE CONFIDENCE. SOUTHWESTERLY
WINDS AND SEAS DIMINISH GRADUALLY. SMALL CRAFT ADVISORIES WILL
LIKELY BE NEEDED FOR MUCH OF THIS TIME AS GUSTS ABOVE 25 KTS ARE
LIKELY.
FRIDAY...MODERATE CONFIDENCE. WINDS AND SEAS REMAIN AT OR JUST
UNDER SMALL CRAFT CRITERIA.
SATURDAY...LOW CONFIDENCE. HIGHLY UNCERTAIN ON WIND SPEED AND
DIRECTION.
&&
.BOX WATCHES/WARNINGS/ADVISORIES...
CT...WINTER WEATHER ADVISORY UNTIL 7 PM EST THIS EVENING FOR
CTZ002>004.
MA...WINTER WEATHER ADVISORY UNTIL 11 PM EST THIS EVENING FOR
MAZ004>007-012-014-026.
WINTER WEATHER ADVISORY UNTIL 8 PM EST THIS EVENING FOR MAZ013-
015>021.
WINTER WEATHER ADVISORY UNTIL 7 PM EST THIS EVENING FOR MAZ002-
003-008>011.
NH...WINTER WEATHER ADVISORY UNTIL 11 PM EST THIS EVENING FOR
NHZ011-012-015.
RI...WINTER WEATHER ADVISORY UNTIL 8 PM EST THIS EVENING FOR
RIZ001>007.
MARINE...SMALL CRAFT ADVISORY FROM NOON TODAY TO 9 PM EST THIS EVENING
FOR ANZ231>235-237.
SMALL CRAFT ADVISORY FROM 5 PM THIS AFTERNOON TO 7 PM EST
WEDNESDAY FOR ANZ250.
SMALL CRAFT ADVISORY FROM NOON TODAY TO 7 PM EST WEDNESDAY FOR
ANZ254>256.
&&
$$
SYNOPSIS...BELK/RLG
NEAR TERM...BELK/RLG
SHORT TERM...BELK
LONG TERM...RLG
AVIATION...BELK/RLG
MARINE...BELK/RLG
AREA FORECAST DISCUSSION
NWS ALBANY NY
638 AM EST TUE DEC 17 2013
.SYNOPSIS...
A LOW PRESSURE SYSTEM PASSING SOUTH OF THE REGION WILL BRING A
WIDESPREAD LIGHT TO MODERATE SNOWFALL TO THE AREA TODAY. THE SNOW
WILL SPREAD NORTHWARD ACROSS THE AREA DURING THIS MORNING AND IS
EXPECTED TO TAPER OFF THIS EVENING. SCATTERED SNOW SHOWERS ARE
THEN EXPECTED TONIGHT AND WEDNESDAY...ESPECIALLY ACROSS THE HIGHER
TERRAIN. A GRADUAL WARMING TREND IS THEN EXPECTED FOR THE END OF
THE WORKWEEK.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
AS OF 615 AM EST...BITTER COLD REIGNS ACROSS THE REGION...WITH
WIDESPREAD TEMPS OF -10F TO -20F ACROSS THE NORTH COUNTRY...AND -5F
TO +5F ELSEWHERE.
CLOUDS ARE RAPIDLY INCREASING ACROSS CENTRAL AND SOUTHERN
AREAS...WITH A RATHER LOW DECK...WITH CIGS GENERALLY BETWEEN
3500-5000 FT AGL. LIGHT SNOW IS CURRENTLY DEVELOPING THE SE
CATSKILLS/MID HUDSON VALLEY REGION...AND WILL SPREAD ACROSS THE
CAPITAL REGION...SCHOHARIE VALLEY...NW CT AND BERKSHIRES BETWEEN
ROUGHLY 7 AM-10 AM...AND INTO THE MOHAWK VALLEY...THE LAKE
GEORGE/SARATOGA REGION AND SOUTHERN VT BETWEEN 10 AM AND NOON.
ONCE THE SNOW STARTS...WE EXPECT PERIODS OF LIGHT TO MODERATE SNOW
TO CONTINUE THROUGH EARLY THIS EVENING...WITH TOTAL ACCUMS
GENERALLY 2-4 INCHES...EXCEPT FOR 3-6 INCHES ACROSS PORTIONS OF
THE MID HUDSON VALLEY...NW CT...BERKSHIRES...SOUTHERN VT AND SE
CATSKILLS WHERE SOME OROGRAPHIC ENHANCEMENT IS LIKELY...AND 1-3
INCHES ACROSS THE SOUTHERN ADIRONDACKS.
IT APPEARS THAT THERE WILL BE 2 MAIN BURSTS OF SNOW THROUGH
TODAY...THE FIRST ONE BEING DRIVEN MAINLY BY LOW/MID LEVEL WARM
ADVECTION...WHICH WILL BE MAINLY THIS MORNING...THEN PERHAPS THE
BEST BURST OF SNOW LATE THIS AFTERNOON INTO EARLY THIS
EVENING...DUE TO ENHANCED 850-700 FRONTOGENESIS TO THE N/NW OF AN
EMBEDDED SHORTWAVE TRANSLATING JUST S/E OF THE
REGION...INTERACTING WITH AN INCREASING INFLUX OF LOW LEVEL
MOISTURE BEING ENTRAINED INTO THE DEVELOPING STORM SYSTEM. THIS
SECOND BURST SHOULD BE GREATEST ACROSS THE GREATER CAPITAL REGION
AND SARATOGA REGION...BERKSHIRES AND SOUTHERN VT...MOST LIKELY
BETWEEN 4 PM AND 7 PM...THEREBY POTENTIALLY ADVERSELY IMPACTING
THE EVENING COMMUTE. WE WILL HAVE TO CLOSELY MONITOR RADAR TRENDS
DURING THIS PERIOD...AS THE ENHANCED F-GEN NOTED ON THE RUC13 FROM
THE CAPITAL REGION EAST INTO THE BERKSHIRES AND SOUTHERN VT
COINCIDES WITH INCREASING MOISTURE/TO NEAR SATURATION/FROM THE
ATLANTIC WITHIN THE 850-700 LAYER...POTENTIALLY ENHANCING BANDING
POTENTIAL AND PERHAPS LEADING TO LOCALLY GREATER SNOWFALL AMTS
THAN CURRENTLY INDICATED.
SINCE NEAR TERM MODELS SUCH AS THE RUC13 AND HRRR HINT AT THIS
SECOND BURST OF SNOW BETWEEN 4 PM AND 7 PM...HAVE EXTENDED THE
WINTER WEATHER ADVISORIES UNTIL 7 PM.
TEMPS TODAY WILL STRUGGLE TO CLIMB INTO AND THROUGH THE TEENS TO
LOWER 20S IN VALLEY AREAS...AND LOWER TO MID TEENS ACROSS HIGHER
ELEVATIONS...WITH MAX TEMPS LIKELY NOT OCCURRING UNTIL BETWEEN 5-7
PM. GIVEN THAT THE CLOUDS WILL BE RATHER LOW...AND THAT MUCH OF
THE PRECIP WILL BE FALLING FROM A LOWER CLOUD DECK INITIALLY THEN
WHAT OCCURRED ON SATURDAY...THE POTENTIAL AND DEPTH OF WET BULB
COOLING WILL BE LESS THAN WHAT OCCURRED THIS PAST SAT. SO...WE
HAVE SIDED WITH THE COOLER SIDE OF A MAV/MET MOS BLEND...BUT DID
NOT STRAY TOO MUCH.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH THURSDAY NIGHT/...
TONIGHT...ANY STEADIER SNOW SHOULD TAPER OFF ACROSS SE VT EARLY.
OTHERWISE...EXPECT SCATTERED SNOW SHOWERS TO OCCUR OVERNIGHT AS
THE MID/UPPER LEVEL TROPOSPHERIC TROUGH AND COLD POOL PASS
THROUGH...WITH 500 MB TEMPS DIPPING INTO THE -35C TO -40C RANGE.
925-700 LAPSE RATES STEEPEN...AND SHOULD ENOUGH MOISTURE BE
PRESENT WITHIN THIS LAYER...COULD LEAD TO SOME EMBEDDED HEAVIER SNOW
SHOWERS AND/OR SQUALLS...LEAVING ADDITIONAL COATINGS...TO PERHAPS
UP TO AN INCH OF SNOWFALL OVERNIGHT. TEMPS SHOULD FALL INTO THE
TEENS IN MOST AREAS.
WED-WED NT...THE AFOREMENTIONED MID LEVEL TROUGH/COLD POOL MOVES E
OF THE REGION IN THE AFTERNOON. HOWEVER...A FAIRLY WELL ALIGNED
WESTERLY FLOW MAY ALLOW FOR LAKE EFFECT SNOWBANDS TO DEVELOP
ACROSS NORTHERN HERKIMER CO IN THE AFTERNOON...AND MAY EXTEND WELL
INTO HAMILTON CO OR EVEN NW WARREN CO FOR A BRIEF TIME LATE IN THE
AFTERNOON INTO EARLY WED NT...AS SUGGESTED PER THE CSTAR FUNDED
INLAND LAKE EXTENT PROGRAM. THIS COULD LEAD TO AT LEAST 1-3 INCHES
OF SNOWFALL...WITH SOME POTENTIAL FOR GREATER AMTS...PERHAPS INTO
THE ADVISORY RANGE. WILL ADDRESS THIS POTENTIAL IN THE HWOALY.
ELSEWHERE...SCATTERED SNOW SHOWERS AND FLURRIES WILL BE POSSIBLE
ACROSS HIGHER ELEVATIONS...WHERE ADDITIONAL MINOR ACCUMS COULD
OCCUR...WITH SOME SNOW SHOWERS/FLURRIES OCCASIONALLY MIGRATING
INTO VALLEY AREAS...ESP NEAR AND N OF THE MOHAWK RIVER. FOR
TEMPS...EXPECT SLIGHTLY MILDER MAX TEMPS WED...REACHING THE 20S TO
LOWER 30S IN VALLEYS...WITH TEENS TO MID 20S ACROSS HIGHER
ELEVATIONS...AND OVERNIGHT MINS WED NT/THU AM FALLING MAINLY INTO
THE TEENS...WITH SOME SINGLE DIGITS POSSIBLE ACROSS NORTHERN AREAS
AND HIGHER ELEVATIONS ACROSS WESTERN NEW ENGLAND.
THU-THU NT...A SOUTHWEST LOW LEVEL FLOW WILL DEVELOP DURING THIS
TIME...ALLOWING FOR GRADUAL MODERATION IN TEMPS. SOME LINGERING
LAKE EFFECT SNOW MAY OCCUR THU ACROSS EXTREME NORTHERN
HERKIMER/HAMILTON COS...BEFORE THE INVERSION LEVEL FALLS.
THEN...SOME WARM ADVECTION PRECIP COULD DEVELOP ACROSS THE WESTERN
DACKS LATE THU NT...IN THE FORM OF LIGHT SNOW...OR EVEN A LIGHT
WINTRY MIX. THU MAX TEMPS SHOULD REACH THE LOWER/MID 30S IN
VALLEYS...AND 20S ACROSS HIGHER ELEVATIONS...WITH OVERNIGHT MINS
THU NT/FRI AM ONLY FALLING INTO THE 20S IN MOST AREAS...WITH TEMPS
POSSIBLY RISING IN SOME AREAS LATE AT NIGHT.
&&
.LONG TERM /FRIDAY THROUGH MONDAY/...
INCREASING AGREEMENT IN THE MODEL AND ENSEMBLE GUIDANCE THROUGH THE
PERIOD. ONE UPPER IMPULSE AND ASSOCIATED FORCING SUPPORTS
PRECIPITATION FRIDAY AND FRIDAY NIGHT. THEN ANOTHER UPPER IMPULSE
AND ASSOCIATED FORCING AFFECTS OUR REGION SATURDAY NIGHT THROUGH
SUNDAY NIGHT. THE TIMING OF THESE SYSTEMS WILL LIKELY GET ADJUSTED
WITH TIME AS THEY ARE WITHIN QUICK WEST SOUTHWEST UPPER CONFLUENT
STEERING FLOW. ALSO...WORDING RAIN AND SNOW THROUGH THE PERIOD SINCE
THERE IS SUCH HIGH UNCERTAINTY IN THE POTENTIAL AREAS OF SLEET
AND/OR FREEZING RAIN.
THE PRECIPITATION TYPES AND THE POSITION OF A POTENTIALLY BROAD
PRECIPITATION TRANSITION ZONE ARE STILL IN QUESTION. HOWEVER...
THERE IS MORE AGREEMENT FOR ANY MIXED PRECIPITATION EARLY FRIDAY
MORNING TO CHANGE TO MAINLY LIQUID PRECIPITATION OVER CENTRAL AND
SOUTHERN AREAS BEFORE COVERAGE OF PRECIPITATION DECREASES FRIDAY
NIGHT. MIXED PRECIPITATION COULD REMAIN MIXED OVER NORTHERN AREAS.
HIGHS FRIDAY IN THE LOWER TO MID 40S IN MANY AREAS WITH MID TO UPPER
30S IN THE HIGHER ELEVATIONS.
LOW LEVEL FORCING WEAKENS FRIDAY NIGHT AND SATURDAY WITH WEAK LOW
LEVEL RIDGING OVER THE REGION. LINGERING MOISTURE AND PROXIMITY TO
THE LOW LEVEL THERMAL GRADIENT AND WIND CONVERGENCE PROXIMATE TO THE
LOW LEVEL BOUNDARY COULD SUPPORT SCATTERED SHOWERS...WITH SOME
FLURRIES OR SNOW SHOWERS. THE BRIEF LOW LEVEL RIDGING COULD ALLOW
TEMPERATURES TO FALL TO NEAR FREEZING IN MANY AREAS FRIDAY NIGHT AND
MID TO UPPER 20S IN THE HIGHER ELEVATIONS... AGAIN SUPPORTING
SCATTERED SHOWERS AND SNOW SHOWERS.
CURRENT GUIDANCE SUGGESTS THE NEXT SYSTEM ARRIVES THROUGH THE DAY
SATURDAY AN CONTINUES SATURDAY NIGHT THROUGH SUNDAY...EXITING SUNDAY
NIGHT. THE WARM ADVECTION AND FORCING LOOK STRONGER WITH THIS
SYSTEM...DRIVING THE WARM AIR FURTHER NORTH...SUPPORTING A
PRECIPITATION TRANSITION TO RAIN IN MOST AREAS. QUITE A STRONG
SOUTHWEST TO WEST SOUTHWEST BOUNDARY LAYER JET TRACKS THROUGH THE
REGION AND THE BOUNDARY LAYER THERMAL GRADIENT IS QUITE TIGHT AS IT
TRACKS EAST AND SOUTH SUNDAY AND SUNDAY NIGHT. SO...WILL HAVE TO
KEEP AN EYE ON WINDS AND POTENTIAL FOR LOCALLY HEAVY RAIN ON THE
MELTING SNOW PACK. HIGHS SATURDAY IN THE LOWER TO MID 40S...LOWER
TO MID 30S HIGHER ELEVATIONS. HIGHS SUNDAY IN THE UPPER 40S TO LOWER
50S...WITH UPPER 30S TO LOWER 40S IN HIGHER ELEVATIONS.
STRONG COLD ADVECTION SPREADS ACROSS THE REGION BY MONDAY MORNING
AND CONTINUES THROUGH THE DAY. SOME LAKE EFFECT SNOW BANDS SHOULD
FORM BUT INLAND EXTENT IS IN QUESTION. HIGHS MONDAY IN THE 20S TO
LOWER 30S.
THERE COULD STILL BE A LOT OF CHANGES TO HOW THESE SYSTEMS DEVELOP
AND IMPACT THE REGION. THERE ARE INDICATIONS OF A POTENTIAL BROAD
MIXED PRECIPITATION TRANSITION ZONE...BUT THE POSITION AND AREAL
EXTENT OF THE PRECIPITATION TRANSITION ZONE KEEPS CHANGING IN
SUCCESSIVE SETS OF GUIDANCE. THERE IS STILL A CHANCE THAT THE
CURRENT INDICATIONS OF MORE RAIN AND LESS WINTERY PRECIPITATION OVER
MUCH OF OUR REGION COULD CHANGE BACK TO COLDER AND MORE MIXED
PRECIPITATION DEPENDING ON HOW THE SYSTEMS DEVELOP IN THE NEXT 3+
DAYS. HOWEVER...THE INCREASING CONSENSUS FROM GUIDANCE OF MORE
LIQUID AND LESS MIXED PRECIPITATION SEEMS THE MOST LIKELY SCENARIO
AT THIS TIME.
&&
.AVIATION /12Z TUESDAY THROUGH SATURDAY/...
A LOW PRESSURE SYSTEM WILL BRING A WIDESPREAD LIGHT TO MODERATE
SNOWFALL TO THE AREA TODAY. THE SNOW WILL SPREAD NORTHWARD ACROSS
THE AREA DURING THE MORNING AND IS EXPECTED TO TAPER OFF TOWARD THIS
EVENING.
SNOW IS BEGINNING AT KPOU AND WILL SPREAD NORTHWARD TO KALB AND KPSF
BY 13Z-14Z AND BY KGFL BY 14Z. INITIALLY MVFR CONDITIONS ARE
EXPECTED WITH IFR DEVELOPING AS THE SNOW BECOMES STEADIER AS THE
MORNING PROGRESSES. AROUND 5 HOURS OF IFR SNOWS ARE EXPECTED WITH AN
IMPROVE BACK TO MVFR MID TO LATE AFTERNOON. KEEPING VCSH THROUGH
ABOUT 05Z AT ALL TAF SITES WITH LINGERING MOISTURE. AFTER
05Z-06Z...VFR CEILINGS AND VISIBILITIES SHOULD PREVAIL AT ALL TAF
SITES.
WINDS WILL BE NEARLY CALM THROUGH THE MORNING HOURS WITH A LIGHT
SOUTHEASTERLY FLOW DEVELOPING LATER IN THE MORNING AND BECOMING
VARIABLE AGAIN BY LATE AFTERNOON AND EVENING.
OUTLOOK...
WEDNESDAY NIGHT: NO OPERATIONAL IMPACT. NO SIG WX.
THURSDAY: NO OPERATIONAL IMPACT. NO SIG WX.
THURSDAY NIGHT: LOW OPERATIONAL IMPACT. SLIGHT CHANCE OF SHSN.
FRIDAY: MODERATE OPERATIONAL IMPACT. CHANCE OF RA...SN.
FRIDAY NIGHT: MODERATE OPERATIONAL IMPACT. SCATTERED SHRA...SHSN.
SATURDAY: MODERATE OPERATIONAL IMPACT. CHANCE OF RA...SN.
&&
.HYDROLOGY...
A CLIPPER TYPE SYSTEM WILL AFFECT THE REGION TODAY INTO THIS
EVENING. THE PRECIPITATION IS EXPECTED TO BE ALL SNOW WITH THIS
SYSTEM. TOTAL LIQUID EQUIVALENT WITH THIS SYSTEM IS EXPECTED TO
RANGE FROM ONE TO THREE TENTHS OF AN INCH WITH THE HIGHEST AMOUNTS
OVER THE ERN CATSKILLS...W-CNTRL MOHAWK VALLEY...AND WRN NEW
ENGLAND. THIS SYSTEM WILL REDEVELOP SOUTH OF LONG ISLAND...AND
QUICKLY MOVE NORTHEAST OF CAPE COD TOMORROW NIGHT.
SOME LAKE EFFECT SNOW IS POSSIBLE WED-THU WITH LIGHT SNOW
AMOUNTS...AND LIQUID EQUIVALENTS GENERALLY LESS THAN A TENTH OF AN
INCH FOR THE WRN DACKS REGION...AND NRN TIER OF THE HSA.
FOR THE MID WEEK...TEMPS WILL CONTINUE TO BE BELOW NORMAL AND ICE
WILL CONTINUE TO FORM AND THICKEN ON AREA RIVERS...STREAMS AND
PARTICULARLY LAKES.
A MODERATING TREND IN TEMPS IS LIKELY THU INTO FRI...WITH A
FRONTAL BOUNDARY BRINGING SOME SHOWERS TO CLOSE THE WORK WEEK.
SOME SNOW MELT IS LIKELY THIS WEEKEND. ALSO...A STORM SYSTEM
MOVING ALONG A FRONTAL BOUNDARY NEAR THE HSA MAY BRING SIGNIFICANT
PCPN TO THE FORECAST AREA SAT NIGHT INTO SUNDAY WITH EVEN MILDER
TEMPS. THIS WILL CONTINUE TO BE MONITORED FOR THE UPCOMING
WEEKEND.
FOR DETAILS ON SPECIFIC AREA RIVERS AND LAKES...INCLUDING OBSERVED
AND FORECAST RIVER STAGES AND LAKE ELEVATIONS...PLEASE VISIT THE
ADVANCED HYDROLOGIC PREDICTION SERVICE /AHPS/ GRAPHS ON OUR WEBSITE.
&&
.ALY WATCHES/WARNINGS/ADVISORIES...
CT...WINTER WEATHER ADVISORY UNTIL 7 PM EST THIS EVENING FOR CTZ001-
013.
NY...WINTER WEATHER ADVISORY UNTIL 7 PM EST THIS EVENING FOR NYZ054-
058>061-063>066.
MA...WINTER WEATHER ADVISORY UNTIL 7 PM EST THIS EVENING FOR MAZ001-
025.
VT...WINTER WEATHER ADVISORY UNTIL 7 PM EST THIS EVENING FOR
VTZ013>015.
&&
$$
SYNOPSIS...KL/WASULA
NEAR TERM...KL
SHORT TERM...KL
LONG TERM...NAS
AVIATION...NAS
HYDROLOGY...KL/WASULA
AREA FORECAST DISCUSSION
NWS ALBANY NY
620 AM EST TUE DEC 17 2013
.SYNOPSIS...
A LOW PRESSURE SYSTEM PASSING SOUTH OF THE REGION WILL BRING A
WIDESPREAD LIGHT TO MODERATE SNOWFALL TO THE AREA TODAY. THE SNOW
WILL SPREAD NORTHWARD ACROSS THE AREA DURING THIS MORNING AND IS
EXPECTED TO TAPER OFF THIS EVENING. SCATTERED SNOW SHOWERS ARE
THEN EXPECTED TONIGHT AND WEDNESDAY...ESPECIALLY ACROSS THE HIGHER
TERRAIN. A GRADUAL WARMING TREND IS THEN EXPECTED FOR THE END OF
THE WORKWEEK.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
AS OF 615 AM EST...BITTER COLD REIGNS ACROSS THE REGION...WITH
WIDESPREAD TEMPS OF -10F TO -20F ACROSS THE NORTH COUNTRY...AND -5F
TO +5F ELSEWHERE.
CLOUDS ARE RAPIDLY INCREASING ACROSS CENTRAL AND SOUTHERN
AREAS...WITH A RATHER LOW DECK...WITH CIGS GENERALLY BETWEEN
3500-5000 FT AGL. LIGHT SNOW IS CURRENTLY DEVELOPING THE SE
CATSKILLS/MID HUDSON VALLEY REGION...AND WILL SPREAD ACROSS THE
CAPITAL REGION...SCHOHARIE VALLEY...NW CT AND BERKSHIRES BETWEEN
ROUGHLY 7 AM-10 AM...AND INTO THE MOHAWK VALLEY...THE LAKE
GEORGE/SARATOGA REGION AND SOUTHERN VT BETWEEN 10 AM AND NOON.
ONCE THE SNOW STARTS...WE EXPECT PERIODS OF LIGHT TO MODERATE SNOW
TO CONTINUE THROUGH EARLY THIS EVENING...WITH TOTAL ACCUMS
GENERALLY 2-4 INCHES...EXCEPT FOR 3-6 INCHES ACROSS PORTIONS OF
THE MID HUDSON VALLEY...NW CT...BERKSHIRES...SOUTHERN VT AND SE
CATSKILLS WHERE SOME OROGRAPHIC ENHANCEMENT IS LIKELY...AND 1-3
INCHES ACROSS THE SOUTHERN ADIRONDACKS.
IT APPEARS THAT THERE WILL BE 2 MAIN BURSTS OF SNOW THROUGH
TODAY...THE FIRST ONE BEING DRIVEN MAINLY BY LOW/MID LEVEL WARM
ADVECTION...WHICH WILL BE MAINLY THIS MORNING...THEN PERHAPS THE
BEST BURST OF SNOW LATE THIS AFTERNOON INTO EARLY THIS
EVENING...DUE TO ENHANCED 850-700 FRONTOGENESIS TO THE N/NW OF AN
EMBEDDED SHORTWAVE TRANSLATING JUST S/E OF THE
REGION...INTERACTING WITH AN INCREASING INFLUX OF LOW LEVEL
MOISTURE BEING ENTRAINED INTO THE DEVELOPING STORM SYSTEM. THIS
SECOND BURST SHOULD BE GREATEST ACROSS THE GREATER CAPITAL REGION
AND SARATOGA REGION...BERKSHIRES AND SOUTHERN VT...MOST LIKELY
BETWEEN 4 PM AND 7 PM...THEREBY POTENTIALLY ADVERSELY IMPACTING
THE EVENING COMMUTE. WE WILL HAVE TO CLOSELY MONITOR RADAR TRENDS
DURING THIS PERIOD...AS THE ENHANCED F-GEN NOTED ON THE RUC13 FROM
THE CAPITAL REGION EAST INTO THE BERKSHIRES AND SOUTHERN VT
COINCIDES WITH INCREASING MOISTURE/TO NEAR SATURATION/FROM THE
ATLANTIC WITHIN THE 850-700 LAYER...POTENTIALLY ENHANCING BANDING
POTENTIAL AND PERHAPS LEADING TO LOCALLY GREATER SNOWFALL AMTS
THAN CURRENTLY INDICATED.
SINCE NEAR TERM MODELS SUCH AS THE RUC13 AND HRRR HINT AT THIS
SECOND BURST OF SNOW BETWEEN 4 PM AND 7 PM...HAVE EXTENDED THE
WINTER WEATHER ADVISORIES UNTIL 7 PM.
TEMPS TODAY WILL STRUGGLE TO CLIMB INTO AND THROUGH THE TEENS TO
LOWER 20S IN VALLEY AREAS...AND LOWER TO MID TEENS ACROSS HIGHER
ELEVATIONS...WITH MAX TEMPS LIKELY NOT OCCURRING UNTIL BETWEEN 5-7
PM. GIVEN THAT THE CLOUDS WILL BE RATHER LOW...AND THAT MUCH OF
THE PRECIP WILL BE FALLING FROM A LOWER CLOUD DECK INITIALLY THEN
WHAT OCCURRED ON SATURDAY...THE POTENTIAL AND DEPTH OF WET BULB
COOLING WILL BE LESS THAN WHAT OCCURRED THIS PAST SAT. SO...WE
HAVE SIDED WITH THE COOLER SIDE OF A MAV/MET MOS BLEND...BUT DID
NOT STRAY TOO MUCH.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH THURSDAY NIGHT/...
TONIGHT...ANY STEADIER SNOW SHOULD TAPER OFF ACROSS SE VT EARLY.
OTHERWISE...EXPECT SCATTERED SNOW SHOWERS TO OCCUR OVERNIGHT AS
THE MID/UPPER LEVEL TROPOSPHERIC TROUGH AND COLD POOL PASS
THROUGH...WITH 500 MB TEMPS DIPPING INTO THE -35C TO -40C RANGE.
925-700 LAPSE RATES STEEPEN...AND SHOULD ENOUGH MOISTURE BE
PRESENT WITHIN THIS LAYER...COULD LEAD TO SOME EMBEDDED HEAVIER SNOW
SHOWERS AND/OR SQUALLS...LEAVING ADDITIONAL COATINGS...TO PERHAPS
UP TO AN INCH OF SNOWFALL OVERNIGHT. TEMPS SHOULD FALL INTO THE
TEENS IN MOST AREAS.
WED-WED NT...THE AFOREMENTIONED MID LEVEL TROUGH/COLD POOL MOVES E
OF THE REGION IN THE AFTERNOON. HOWEVER...A FAIRLY WELL ALIGNED
WESTERLY FLOW MAY ALLOW FOR LAKE EFFECT SNOWBANDS TO DEVELOP
ACROSS NORTHERN HERKIMER CO IN THE AFTERNOON...AND MAY EXTEND WELL
INTO HAMILTON CO OR EVEN NW WARREN CO FOR A BRIEF TIME LATE IN THE
AFTERNOON INTO EARLY WED NT...AS SUGGESTED PER THE CSTAR FUNDED
INLAND LAKE EXTENT PROGRAM. THIS COULD LEAD TO AT LEAST 1-3 INCHES
OF SNOWFALL...WITH SOME POTENTIAL FOR GREATER AMTS...PERHAPS INTO
THE ADVISORY RANGE. WILL ADDRESS THIS POTENTIAL IN THE HWOALY.
ELSEWHERE...SCATTERED SNOW SHOWERS AND FLURRIES WILL BE POSSIBLE
ACROSS HIGHER ELEVATIONS...WHERE ADDITIONAL MINOR ACCUMS COULD
OCCUR...WITH SOME SNOW SHOWERS/FLURRIES OCCASIONALLY MIGRATING
INTO VALLEY AREAS...ESP NEAR AND N OF THE MOHAWK RIVER. FOR
TEMPS...EXPECT SLIGHTLY MILDER MAX TEMPS WED...REACHING THE 20S TO
LOWER 30S IN VALLEYS...WITH TEENS TO MID 20S ACROSS HIGHER
ELEVATIONS...AND OVERNIGHT MINS WED NT/THU AM FALLING MAINLY INTO
THE TEENS...WITH SOME SINGLE DIGITS POSSIBLE ACROSS NORTHERN AREAS
AND HIGHER ELEVATIONS ACROSS WESTERN NEW ENGLAND.
THU-THU NT...A SOUTHWEST LOW LEVEL FLOW WILL DEVELOP DURING THIS
TIME...ALLOWING FOR GRADUAL MODERATION IN TEMPS. SOME LINGERING
LAKE EFFECT SNOW MAY OCCUR THU ACROSS EXTREME NORTHERN
HERKIMER/HAMILTON COS...BEFORE THE INVERSION LEVEL FALLS.
THEN...SOME WARM ADVECTION PRECIP COULD DEVELOP ACROSS THE WESTERN
DACKS LATE THU NT...IN THE FORM OF LIGHT SNOW...OR EVEN A LIGHT
WINTRY MIX. THU MAX TEMPS SHOULD REACH THE LOWER/MID 30S IN
VALLEYS...AND 20S ACROSS HIGHER ELEVATIONS...WITH OVERNIGHT MINS
THU NT/FRI AM ONLY FALLING INTO THE 20S IN MOST AREAS...WITH TEMPS
POSSIBLY RISING IN SOME AREAS LATE AT NIGHT.
&&
.LONG TERM /FRIDAY THROUGH MONDAY/...
INCREASING AGREEMENT IN THE MODEL AND ENSEMBLE GUIDANCE THROUGH THE
PERIOD. ONE UPPER IMPULSE AND ASSOCIATED FORCING SUPPORTS
PRECIPITATION FRIDAY AND FRIDAY NIGHT. THEN ANOTHER UPPER IMPULSE
AND ASSOCIATED FORCING AFFECTS OUR REGION SATURDAY NIGHT THROUGH
SUNDAY NIGHT. THE TIMING OF THESE SYSTEMS WILL LIKELY GET ADJUSTED
WITH TIME AS THEY ARE WITHIN QUICK WEST SOUTHWEST UPPER CONFLUENT
STEERING FLOW. ALSO...WORDING RAIN AND SNOW THROUGH THE PERIOD SINCE
THERE IS SUCH HIGH UNCERTAINTY IN THE POTENTIAL AREAS OF SLEET
AND/OR FREEZING RAIN.
THE PRECIPITATION TYPES AND THE POSITION OF A POTENTIALLY BROAD
PRECIPITATION TRANSITION ZONE ARE STILL IN QUESTION. HOWEVER...
THERE IS MORE AGREEMENT FOR ANY MIXED PRECIPITATION EARLY FRIDAY
MORNING TO CHANGE TO MAINLY LIQUID PRECIPITATION OVER CENTRAL AND
SOUTHERN AREAS BEFORE COVERAGE OF PRECIPITATION DECREASES FRIDAY
NIGHT. MIXED PRECIPITATION COULD REMAIN MIXED OVER NORTHERN AREAS.
HIGHS FRIDAY IN THE LOWER TO MID 40S IN MANY AREAS WITH MID TO UPPER
30S IN THE HIGHER ELEVATIONS.
LOW LEVEL FORCING WEAKENS FRIDAY NIGHT AND SATURDAY WITH WEAK LOW
LEVEL RIDGING OVER THE REGION. LINGERING MOISTURE AND PROXIMITY TO
THE LOW LEVEL THERMAL GRADIENT AND WIND CONVERGENCE PROXIMATE TO THE
LOW LEVEL BOUNDARY COULD SUPPORT SCATTERED SHOWERS...WITH SOME
FLURRIES OR SNOW SHOWERS. THE BRIEF LOW LEVEL RIDGING COULD ALLOW
TEMPERATURES TO FALL TO NEAR FREEZING IN MANY AREAS FRIDAY NIGHT AND
MID TO UPPER 20S IN THE HIGHER ELEVATIONS... AGAIN SUPPORTING
SCATTERED SHOWERS AND SNOW SHOWERS.
CURRENT GUIDANCE SUGGESTS THE NEXT SYSTEM ARRIVES THROUGH THE DAY
SATURDAY AN CONTINUES SATURDAY NIGHT THROUGH SUNDAY...EXITING SUNDAY
NIGHT. THE WARM ADVECTION AND FORCING LOOK STRONGER WITH THIS
SYSTEM...DRIVING THE WARM AIR FURTHER NORTH...SUPPORTING A
PRECIPITATION TRANSITION TO RAIN IN MOST AREAS. QUITE A STRONG
SOUTHWEST TO WEST SOUTHWEST BOUNDARY LAYER JET TRACKS THROUGH THE
REGION AND THE BOUNDARY LAYER THERMAL GRADIENT IS QUITE TIGHT AS IT
TRACKS EAST AND SOUTH SUNDAY AND SUNDAY NIGHT. SO...WILL HAVE TO
KEEP AN EYE ON WINDS AND POTENTIAL FOR LOCALLY HEAVY RAIN ON THE
MELTING SNOW PACK. HIGHS SATURDAY IN THE LOWER TO MID 40S...LOWER
TO MID 30S HIGHER ELEVATIONS. HIGHS SUNDAY IN THE UPPER 40S TO LOWER
50S...WITH UPPER 30S TO LOWER 40S IN HIGHER ELEVATIONS.
STRONG COLD ADVECTION SPREADS ACROSS THE REGION BY MONDAY MORNING
AND CONTINUES THROUGH THE DAY. SOME LAKE EFFECT SNOW BANDS SHOULD
FORM BUT INLAND EXTENT IS IN QUESTION. HIGHS MONDAY IN THE 20S TO
LOWER 30S.
THERE COULD STILL BE A LOT OF CHANGES TO HOW THESE SYSTEMS DEVELOP
AND IMPACT THE REGION. THERE ARE INDICATIONS OF A POTENTIAL BROAD
MIXED PRECIPITATION TRANSITION ZONE...BUT THE POSITION AND AREAL
EXTENT OF THE PRECIPITATION TRANSITION ZONE KEEPS CHANGING IN
SUCCESSIVE SETS OF GUIDANCE. THERE IS STILL A CHANCE THAT THE
CURRENT INDICATIONS OF MORE RAIN AND LESS WINTERY PRECIPITATION OVER
MUCH OF OUR REGION COULD CHANGE BACK TO COLDER AND MORE MIXED
PRECIPITATION DEPENDING ON HOW THE SYSTEMS DEVELOP IN THE NEXT 3+
DAYS. HOWEVER...THE INCREASING CONSENSUS FROM GUIDANCE OF MORE
LIQUID AND LESS MIXED PRECIPITATION SEEMS THE MOST LIKELY SCENARIO
AT THIS TIME.
&&
.AVIATION /11Z TUESDAY THROUGH SATURDAY/...
HIGH PRESSURE WILL SHIFT EASTWARD ACROSS THE THROUGH THE EARLY
MORNING HOURS. A LOW PRESSURE SYSTEM WILL BRING A WIDESPREAD LIGHT
TO MODERATE SNOWFALL TO THE AREA TODAY. THE SNOW WILL SPREAD
NORTHWARD ACROSS THE AREA DURING THE MORNING AND IS EXPECTED TO
TAPER OFF BY LATE AFTERNOON.
EXPECTING VFR CONDITIONS TO PREVAIL THROUGH THE EARLY MORNING HOURS.
CLOUDS WILL STREAM IN TOWARD SUNRISE...THICKENING AND LOWERING
QUICKLY THROUGH THE MORNING AS THE WARM ADVECTION SNOWFALL MOVES IN.
SNOW IS EXPECTED TO COMMENCE AT KPOU AROUND SUNRISE AND SPREAD
NORTHWARD TO KALB AND KPSF BY MID MORNING AND BY KGFL BY LATE
MORNING. INITIALLY MVFR CONDITIONS ARE EXPECTED WITH IFR DEVELOPING
AS THE SNOW BECOMES STEADIER AS THE MORNING PROGRESSES. AROUND 5
HOURS OF IFR SNOWS ARE EXPECTED WITH AN IMPROVE BACK TO MVFR MID TO
LATE AFTERNOON.
WINDS WILL BE NEARLY CALM THROUGH THE EARLY MORNING HOURS WITH A
LIGHT SOUTHEASTERLY FLOW DEVELOPING LATER IN THE MORNING AND
BECOMING VARIABLE AGAIN BY LATE AFTERNOON AND EVENING.
OUTLOOK...
WEDNESDAY NIGHT: NO OPERATIONAL IMPACT. NO SIG WX.
THURSDAY: NO OPERATIONAL IMPACT. NO SIG WX.
THURSDAY NIGHT: LOW OPERATIONAL IMPACT. SLIGHT CHANCE OF SHSN.
FRIDAY: MODERATE OPERATIONAL IMPACT. CHANCE OF RA...SN.
FRIDAY NIGHT: MODERATE OPERATIONAL IMPACT. SCATTERED SHRA...SHSN.
SATURDAY: MODERATE OPERATIONAL IMPACT. CHANCE OF RA...SN.
&&
.HYDROLOGY...
A CLIPPER TYPE SYSTEM WILL AFFECT THE REGION TODAY INTO THIS
EVENING. THE PRECIPITATION IS EXPECTED TO BE ALL SNOW WITH THIS
SYSTEM. TOTAL LIQUID EQUIVALENT WITH THIS SYSTEM IS EXPECTED TO
RANGE FROM ONE TO THREE TENTHS OF AN INCH WITH THE HIGHEST AMOUNTS
OVER THE ERN CATSKILLS...W-CNTRL MOHAWK VALLEY...AND WRN NEW
ENGLAND. THIS SYSTEM WILL REDEVELOP SOUTH OF LONG ISLAND...AND
QUICKLY MOVE NORTHEAST OF CAPE COD TOMORROW NIGHT.
SOME LAKE EFFECT SNOW IS POSSIBLE WED-THU WITH LIGHT SNOW
AMOUNTS...AND LIQUID EQUIVALENTS GENERALLY LESS THAN A TENTH OF AN
INCH FOR THE WRN DACKS REGION...AND NRN TIER OF THE HSA.
FOR THE MID WEEK...TEMPS WILL CONTINUE TO BE BELOW NORMAL AND ICE
WILL CONTINUE TO FORM AND THICKEN ON AREA RIVERS...STREAMS AND
PARTICULARLY LAKES.
A MODERATING TREND IN TEMPS IS LIKELY THU INTO FRI...WITH A
FRONTAL BOUNDARY BRINGING SOME SHOWERS TO CLOSE THE WORK WEEK.
SOME SNOW MELT IS LIKELY THIS WEEKEND. ALSO...A STORM SYSTEM
MOVING ALONG A FRONTAL BOUNDARY NEAR THE HSA MAY BRING SIGNIFICANT
PCPN TO THE FORECAST AREA SAT NIGHT INTO SUNDAY WITH EVEN MILDER
TEMPS. THIS WILL CONTINUE TO BE MONITORED FOR THE UPCOMING
WEEKEND.
FOR DETAILS ON SPECIFIC AREA RIVERS AND LAKES...INCLUDING OBSERVED
AND FORECAST RIVER STAGES AND LAKE ELEVATIONS...PLEASE VISIT THE
ADVANCED HYDROLOGIC PREDICTION SERVICE /AHPS/ GRAPHS ON OUR WEBSITE.
&&
.ALY WATCHES/WARNINGS/ADVISORIES...
CT...WINTER WEATHER ADVISORY UNTIL 7 PM EST THIS EVENING FOR CTZ001-
013.
NY...WINTER WEATHER ADVISORY UNTIL 7 PM EST THIS EVENING FOR NYZ054-
058>061-063>066.
MA...WINTER WEATHER ADVISORY UNTIL 7 PM EST THIS EVENING FOR MAZ001-
025.
VT...WINTER WEATHER ADVISORY UNTIL 7 PM EST THIS EVENING FOR
VTZ013>015.
&&
$$
SYNOPSIS...KL/WASULA
NEAR TERM...KL
SHORT TERM...KL
LONG TERM...NAS
AVIATION...NAS
HYDROLOGY...KL/WASULA
AREA FORECAST DISCUSSION
NWS ALBANY NY
458 AM EST TUE DEC 17 2013
.SYNOPSIS...
A LOW PRESSURE SYSTEM PASSING SOUTH OF THE REGION WILL BRING A
WIDESPREAD LIGHT TO MODERATE SNOWFALL TO THE AREA TODAY. THE SNOW
WILL SPREAD NORTHWARD ACROSS THE AREA DURING THIS MORNING AND IS
EXPECTED TO TAPER OFF THIS EVENING. SCATTERED SNOW SHOWERS ARE
THEN EXPECTED TONIGHT AND WEDNESDAY...ESPECIALLY ACROSS THE HIGHER
TERRAIN. A GRADUAL WARMING TREND IS THEN EXPECTED FOR THE END OF
THE WORKWEEK.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
AS OF 445 AM EST...BITTER COLD REIGNS ACROSS THE REGION...WITH
WIDESPREAD TEMPS OF -10F TO -20F ACROSS THE NORTH COUNTRY...AND -5F
TO +5F ELSEWHERE.
CLOUDS ARE RAPIDLY INCREASING ACROSS SOUTHERN AREAS...WITH A
RATHER LOW DECK...WITH CIGS GENERALLY BETWEEN 3500-5000 FT AGL.
LIGHT SNOW IS CURRENTLY DEVELOPING ACROSS MUCH OF CENTRAL/EASTERN
PA AND SW NJ...AND SHOULD CONTINUE EXPANDING NE...REACHING THE SE
CATSKILLS/MID HUDSON VALLEY REGION AROUND DAYBREAK...AND THEN INTO
THE CAPITAL REGION...SCHOHARIE VALLEY...NW CT AND BERKSHIRES
BETWEEN ROUGHLY 7 AM-10 AM...AND INTO THE MOHAWK VALLEY...THE LAKE
GEORGE/SARATOGA REGION AND SOUTHERN VT BETWEEN 10 AM AND NOON.
ONCE THE SNOW STARTS...WE EXPECT PERIODS OF LIGHT TO MODERATE SNOW
TO CONTINUE THROUGH EARLY THIS EVENING...WITH TOTAL ACCUMS
GENERALLY 2-4 INCHES...EXCEPT FOR 3-6 INCHES ACROSS PORTIONS OF
THE MID HUDSON VALLEY...NW CT...BERKSHIRES...SOUTHERN VT AND SE
CATSKILLS WHERE SOME OROGRAPHIC ENHANCEMENT IS LIKELY...AND 1-3
INCHES ACROSS THE SOUTHERN ADIRONDACKS.
IT APPEARS THAT THERE WILL BE 2 MAIN BURSTS OF SNOW THROUGH
TODAY...THE FIRST ONE BEING DRIVEN MAINLY BY LOW/MID LEVEL WARM
ADVECTION...WHICH WILL BE MAINLY THIS MORNING...THEN PERHAPS THE
BEST BURST OF SNOW LATE THIS AFTERNOON INTO EARLY THIS
EVENING...DUE TO ENHANCED 850-700 FRONTOGENESIS TO THE N/NW OF AN
EMBEDDED SHORTWAVE TRANSLATING JUST S/E OF THE
REGION...INTERACTING WITH AN INCREASING INFLUX OF LOW LEVEL
MOISTURE BEING ENTRAINED INTO THE DEVELOPING STORM SYSTEM. THIS
SECOND BURST SHOULD BE GREATEST ACROSS THE GREATER CAPITAL REGION
AND SARATOGA REGION...BERKSHIRES AND SOUTHERN VT...MOST LIKELY
BETWEEN 4 PM AND 7 PM...THEREBY POTENTIALLY ADVERSELY IMPACTING
THE EVENING COMMUTE. WE WILL HAVE TO CLOSELY MONITOR RADAR TRENDS
DURING THIS PERIOD...AS THE ENHANCED F-GEN NOTED ON THE RUC13 FROM
THE CAPITAL REGION EAST INTO THE BERKSHIRES AND SOUTHERN VT
COINCIDES WITH INCREASING MOISTURE/TO NEAR SATURATION/FROM THE
ATLANTIC WITHIN THE 850-700 LAYER...POTENTIALLY ENHANCING BANDING
POTENTIAL AND PERHAPS LEADING TO LOCALLY GREATER SNOWFALL AMTS
THAN CURRENTLY INDICATED.
SINCE NEAR TERM MODELS SUCH AS THE RUC13 AND HRRR HINT AT THIS
SECOND BURST OF SNOW BETWEEN 4 PM AND 7 PM...HAVE EXTENDED THE
WINTER WEATHER ADVISORIES UNTIL 7 PM.
TEMPS TODAY WILL STRUGGLE TO CLIMB INTO AND THROUGH THE TEENS TO
LOWER 20S IN VALLEY AREAS...AND LOWER TO MID TEENS ACROSS HIGHER
ELEVATIONS...WITH MAX TEMPS LIKELY NOT OCCURRING UNTIL BETWEEN 5-7
PM. GIVEN THAT THE CLOUDS WILL BE RATHER LOW...AND THAT MUCH OF
THE PRECIP WILL BE FALLING FROM A LOWER CLOUD DECK INITIALLY THEN
WHAT OCCURRED ON SATURDAY...THE POTENTIAL AND DEPTH OF WET BULB
COOLING WILL BE LESS THAN WHAT OCCURRED THIS PAST SAT. SO...WE
HAVE SIDED WITH THE COOLER SIDE OF A MAV/MET MOS BLEND...BUT DID
NOT STRAY TOO MUCH.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH THURSDAY NIGHT/...
TONIGHT...ANY STEADIER SNOW SHOULD TAPER OFF ACROSS SE VT EARLY.
OTHERWISE...EXPECT SCATTERED SNOW SHOWERS TO OCCUR OVERNIGHT AS
THE MID/UPPER LEVEL TROPOSPHERIC TROUGH AND COLD POOL PASS
THROUGH...WITH 500 MB TEMPS DIPPING INTO THE -35C TO -40C RANGE.
925-700 LAPSE RATES STEEPEN...AND SHOULD ENOUGH MOISTURE BE
PRESENT WITHIN THIS LAYER...COULD LEAD TO SOME EMBEDDED HEAVIER SNOW
SHOWERS AND/OR SQUALLS...LEAVING ADDITIONAL COATINGS...TO PERHAPS
UP TO AN INCH OF SNOWFALL OVERNIGHT. TEMPS SHOULD FALL INTO THE
TEENS IN MOST AREAS.
WED-WED NT...THE AFOREMENTIONED MID LEVEL TROUGH/COLD POOL MOVES E
OF THE REGION IN THE AFTERNOON. HOWEVER...A FAIRLY WELL ALIGNED
WESTERLY FLOW MAY ALLOW FOR LAKE EFFECT SNOWBANDS TO DEVELOP
ACROSS NORTHERN HERKIMER CO IN THE AFTERNOON...AND MAY EXTEND WELL
INTO HAMILTON CO OR EVEN NW WARREN CO FOR A BRIEF TIME LATE IN THE
AFTERNOON INTO EARLY WED NT...AS SUGGESTED PER THE CSTAR FUNDED
INLAND LAKE EXTENT PROGRAM. THIS COULD LEAD TO AT LEAST 1-3 INCHES
OF SNOWFALL...WITH SOME POTENTIAL FOR GREATER AMTS...PERHAPS INTO
THE ADVISORY RANGE. WILL ADDRESS THIS POTENTIAL IN THE HWOALY.
ELSEWHERE...SCATTERED SNOW SHOWERS AND FLURRIES WILL BE POSSIBLE
ACROSS HIGHER ELEVATIONS...WHERE ADDITIONAL MINOR ACCUMS COULD
OCCUR...WITH SOME SNOW SHOWERS/FLURRIES OCCASIONALLY MIGRATING
INTO VALLEY AREAS...ESP NEAR AND N OF THE MOHAWK RIVER. FOR
TEMPS...EXPECT SLIGHTLY MILDER MAX TEMPS WED...REACHING THE 20S TO
LOWER 30S IN VALLEYS...WITH TEENS TO MID 20S ACROSS HIGHER
ELEVATIONS...AND OVERNIGHT MINS WED NT/THU AM FALLING MAINLY INTO
THE TEENS...WITH SOME SINGLE DIGITS POSSIBLE ACROSS NORTHERN AREAS
AND HIGHER ELEVATIONS ACROSS WESTERN NEW ENGLAND.
THU-THU NT...A SOUTHWEST LOW LEVEL FLOW WILL DEVELOP DURING THIS
TIME...ALLOWING FOR GRADUAL MODERATION IN TEMPS. SOME LINGERING
LAKE EFFECT SNOW MAY OCCUR THU ACROSS EXTREME NORTHERN
HERKIMER/HAMILTON COS...BEFORE THE INVERSION LEVEL FALLS.
THEN...SOME WARM ADVECTION PRECIP COULD DEVELOP ACROSS THE WESTERN
DACKS LATE THU NT...IN THE FORM OF LIGHT SNOW...OR EVEN A LIGHT
WINTRY MIX. THU MAX TEMPS SHOULD REACH THE LOWER/MID 30S IN
VALLEYS...AND 20S ACROSS HIGHER ELEVATIONS...WITH OVERNIGHT MINS
THU NT/FRI AM ONLY FALLING INTO THE 20S IN MOST AREAS...WITH TEMPS
POSSIBLY RISING IN SOME AREAS LATE AT NIGHT.
&&
.LONG TERM /FRIDAY THROUGH MONDAY/...
INCREASING AGREEMENT IN THE MODEL AND ENSEMBLE GUIDANCE THROUGH THE
PERIOD. ONE UPPER IMPULSE AND ASSOCIATED FORCING SUPPORTS
PRECIPITATION FRIDAY AND FRIDAY NIGHT. THEN ANOTHER UPPER IMPULSE
AND ASSOCIATED FORCING AFFECTS OUR REGION SATURDAY NIGHT THROUGH
SUNDAY NIGHT. THE TIMING OF THESE SYSTEMS WILL LIKELY GET ADJUSTED
WITH TIME AS THEY ARE WITHIN QUICK WEST SOUTHWEST UPPER CONFLUENT
STEERING FLOW. ALSO...WORDING RAIN AND SNOW THROUGH THE PERIOD SINCE
THERE IS SUCH HIGH UNCERTAINTY IN THE POTENTIAL AREAS OF SLEET
AND/OR FREEZING RAIN.
THE PRECIPITATION TYPES AND THE POSITION OF A POTENTIALLY BROAD
PRECIPITATION TRANSITION ZONE ARE STILL IN QUESTION. HOWEVER...
THERE IS MORE AGREEMENT FOR ANY MIXED PRECIPITATION EARLY FRIDAY
MORNING TO CHANGE TO MAINLY LIQUID PRECIPITATION OVER CENTRAL AND
SOUTHERN AREAS BEFORE COVERAGE OF PRECIPITATION DECREASES FRIDAY
NIGHT. MIXED PRECIPITATION COULD REMAIN MIXED OVER NORTHERN AREAS.
HIGHS FRIDAY IN THE LOWER TO MID 40S IN MANY AREAS WITH MID TO UPPER
30S IN THE HIGHER ELEVATIONS.
LOW LEVEL FORCING WEAKENS FRIDAY NIGHT AND SATURDAY WITH WEAK LOW
LEVEL RIDGING OVER THE REGION. LINGERING MOISTURE AND PROXIMITY TO
THE LOW LEVEL THERMAL GRADIENT AND WIND CONVERGENCE PROXIMATE TO THE
LOW LEVEL BOUNDARY COULD SUPPORT SCATTERED SHOWERS...WITH SOME
FLURRIES OR SNOW SHOWERS. THE BRIEF LOW LEVEL RIDGING COULD ALLOW
TEMPERATURES TO FALL TO NEAR FREEZING IN MANY AREAS FRIDAY NIGHT AND
MID TO UPPER 20S IN THE HIGHER ELEVATIONS... AGAIN SUPPORTING
SCATTERED SHOWERS AND SNOW SHOWERS.
CURRENT GUIDANCE SUGGESTS THE NEXT SYSTEM ARRIVES THROUGH THE DAY
SATURDAY AN CONTINUES SATURDAY NIGHT THROUGH SUNDAY...EXITING SUNDAY
NIGHT. THE WARM ADVECTION AND FORCING LOOK STRONGER WITH THIS
SYSTEM...DRIVING THE WARM AIR FURTHER NORTH...SUPPORTING A
PRECIPITATION TRANSITION TO RAIN IN MOST AREAS. QUITE A STRONG
SOUTHWEST TO WEST SOUTHWEST BOUNDARY LAYER JET TRACKS THROUGH THE
REGION AND THE BOUNDARY LAYER THERMAL GRADIENT IS QUITE TIGHT AS IT
TRACKS EAST AND SOUTH SUNDAY AND SUNDAY NIGHT. SO...WILL HAVE TO
KEEP AN EYE ON WINDS AND POTENTIAL FOR LOCALLY HEAVY RAIN ON THE
MELTING SNOW PACK. HIGHS SATURDAY IN THE LOWER TO MID 40S...LOWER
TO MID 30S HIGHER ELEVATIONS. HIGHS SUNDAY IN THE UPPER 40S TO LOWER
50S...WITH UPPER 30S TO LOWER 40S IN HIGHER ELEVATIONS.
STRONG COLD ADVECTION SPREADS ACROSS THE REGION BY MONDAY MORNING
AND CONTINUES THROUGH THE DAY. SOME LAKE EFFECT SNOW BANDS SHOULD
FORM BUT INLAND EXTENT IS IN QUESTION. HIGHS MONDAY IN THE 20S TO
LOWER 30S.
THERE COULD STILL BE A LOT OF CHANGES TO HOW THESE SYSTEMS DEVELOP
AND IMPACT THE REGION. THERE ARE INDICATIONS OF A POTENTIAL BROAD
MIXED PRECIPITATION TRANSITION ZONE...BUT THE POSITION AND AREAL
EXTENT OF THE PRECIPITATION TRANSITION ZONE KEEPS CHANGING IN
SUCCESSIVE SETS OF GUIDANCE. THERE IS STILL A CHANCE THAT THE
CURRENT INDICATIONS OF MORE RAIN AND LESS WINTERY PRECIPITATION OVER
MUCH OF OUR REGION COULD CHANGE BACK TO COLDER AND MORE MIXED
PRECIPITATION DEPENDING ON HOW THE SYSTEMS DEVELOP IN THE NEXT 3+
DAYS. HOWEVER...THE INCREASING CONSENSUS FROM GUIDANCE OF MORE
LIQUID AND LESS MIXED PRECIPITATION SEEMS THE MOST LIKELY SCENARIO
AT THIS TIME.
&&
.AVIATION /10Z TUESDAY THROUGH SATURDAY/...
HIGH PRESSURE WILL SHIFT EASTWARD ACROSS THE THROUGH THE EARLY
MORNING HOURS. A LOW PRESSURE SYSTEM WILL BRING A WIDESPREAD LIGHT
TO MODERATE SNOWFALL TO THE AREA TODAY. THE SNOW WILL SPREAD
NORTHWARD ACROSS THE AREA DURING THE MORNING AND IS EXPECTED TO
TAPER OFF BY LATE AFTERNOON.
EXPECTING VFR CONDITIONS TO PREVAIL THROUGH THE EARLY MORNING HOURS.
CLOUDS WILL STREAM IN TOWARD SUNRISE...THICKENING AND LOWERING
QUICKLY THROUGH THE MORNING AS THE WARM ADVECTION SNOWFALL MOVES IN.
SNOW IS EXPECTED TO COMMENCE AT KPOU AROUND SUNRISE AND SPREAD
NORTHWARD TO KALB AND KPSF BY MID MORNING AND BY KGFL BY LATE
MORNING. INITIALLY MVFR CONDITIONS ARE EXPECTED WITH IFR DEVELOPING
AS THE SNOW BECOMES STEADIER AS THE MORNING PROGRESSES. AROUND 5
HOURS OF IFR SNOWS ARE EXPECTED WITH AN IMPROVE BACK TO MVFR MID TO
LATE AFTERNOON.
WINDS WILL BE NEARLY CALM THROUGH THE EARLY MORNING HOURS WITH A
LIGHT SOUTHEASTERLY FLOW DEVELOPING LATER IN THE MORNING AND
BECOMING VARIABLE AGAIN BY LATE AFTERNOON AND EVENING.
OUTLOOK...
WEDNESDAY NIGHT: NO OPERATIONAL IMPACT. NO SIG WX.
THURSDAY: NO OPERATIONAL IMPACT. NO SIG WX.
THURSDAY NIGHT: LOW OPERATIONAL IMPACT. SLIGHT CHANCE OF SHSN.
FRIDAY: MODERATE OPERATIONAL IMPACT. CHANCE OF RA...SN.
FRIDAY NIGHT: MODERATE OPERATIONAL IMPACT. SCATTERED SHRA...SHSN.
SATURDAY: MODERATE OPERATIONAL IMPACT. CHANCE OF RA...SN.
&&
.HYDROLOGY...
A CLIPPER TYPE SYSTEM WILL AFFECT THE REGION TODAY INTO THIS
EVENING. THE PRECIPITATION IS EXPECTED TO BE ALL SNOW WITH THIS
SYSTEM. TOTAL LIQUID EQUIVALENT WITH THIS SYSTEM IS EXPECTED TO
RANGE FROM ONE TO THREE TENTHS OF AN INCH WITH THE HIGHEST AMOUNTS
OVER THE ERN CATSKILLS...W-CNTRL MOHAWK VALLEY...AND WRN NEW
ENGLAND. THIS SYSTEM WILL REDEVELOP SOUTH OF LONG ISLAND...AND
QUICKLY MOVE NORTHEAST OF CAPE COD TOMORROW NIGHT.
SOME LAKE EFFECT SNOW IS POSSIBLE WED-THU WITH LIGHT SNOW
AMOUNTS...AND LIQUID EQUIVALENTS GENERALLY LESS THAN A TENTH OF AN
INCH FOR THE WRN DACKS REGION...AND NRN TIER OF THE HSA.
FOR THE MID WEEK...TEMPS WILL CONTINUE TO BE BELOW NORMAL AND ICE
WILL CONTINUE TO FORM AND THICKEN ON AREA RIVERS...STREAMS AND
PARTICULARLY LAKES.
A MODERATING TREND IN TEMPS IS LIKELY THU INTO FRI...WITH A
FRONTAL BOUNDARY BRINGING SOME SHOWERS TO CLOSE THE WORK WEEK.
SOME SNOW MELT IS LIKELY THIS WEEKEND. ALSO...A STORM SYSTEM
MOVING ALONG A FRONTAL BOUNDARY NEAR THE HSA MAY BRING SIGNIFICANT
PCPN TO THE FORECAST AREA SAT NIGHT INTO SUNDAY WITH EVEN MILDER
TEMPS. THIS WILL CONTINUE TO BE MONITORED FOR THE UPCOMING
WEEKEND.
FOR DETAILS ON SPECIFIC AREA RIVERS AND LAKES...INCLUDING OBSERVED
AND FORECAST RIVER STAGES AND LAKE ELEVATIONS...PLEASE VISIT THE
ADVANCED HYDROLOGIC PREDICTION SERVICE /AHPS/ GRAPHS ON OUR WEBSITE.
&&
.ALY WATCHES/WARNINGS/ADVISORIES...
CT...WINTER WEATHER ADVISORY UNTIL 7 PM EST THIS EVENING FOR CTZ001-
013.
NY...WINTER WEATHER ADVISORY UNTIL 7 PM EST THIS EVENING FOR NYZ054-
058>061-063>066.
MA...WINTER WEATHER ADVISORY UNTIL 7 PM EST THIS EVENING FOR MAZ001-
025.
VT...WINTER WEATHER ADVISORY UNTIL 7 PM EST THIS EVENING FOR
VTZ013>015.
&&
$$
SYNOPSIS...KL/WASULA
NEAR TERM...KL
SHORT TERM...KL
LONG TERM...NAS
AVIATION...NAS
HYDROLOGY...KL/WASULA
AREA FORECAST DISCUSSION
NWS COLUMBIA SC
1245 PM EST TUE DEC 17 2013
.SYNOPSIS...
HIGH PRESSURE OVER THE SOUTHERN STATES WILL SLIP WESTWARD THIS
AFTERNOON ALLOWING A MOISTURE STARVED COLD FRONT TO CROSS OUR AREA
THIS EVENING. HIGH PRESSURE WILL BUILD ACROSS THE REGION WEDNESDAY
THEN SLIDE OFF THE SOUTHEAST COAST THURSDAY. A SOUTHERLY FLOW WILL
BRING MUCH ABOVE NORMAL TEMPERATURES TO THE AREA FOR THE WEEKEND.
&&
.NEAR TERM /THROUGH TONIGHT/...
HIGH PRESSURE STRETCHED ACROSS THE GULF COAST STATES THIS
AFTERNOON WITH A COLD FRONT EXTENDING FROM PA THROUGH KY TO AR.
OUR AIR MASS REMAINED DRY WITH PWAT LESS THAN 0.50 INCHES. STILL
EXPECT CLEAR SKIES TO HOLD ACROSS THE AREA. THE FRONT WILL MOVE
THROUGH THE FORECAST AREA EARLY TONIGHT.
IT WILL BE WARM AND BREEZY AHEAD OF THE FRONT THIS AFTERNOON. THE
NAM BUFKIT MOMENTUM TRANSFER TOOL SUPPORTS GUSTS AROUND 20 KNOTS.
THE 10Z HRRR INDICATES GUSTS OF 20 TO 25 KNOTS. LEANED TOWARD THE
WARMER TEMPERATURE GUIDANCE THIS AFTERNOON GIVEN DRY AIR MASS AND
WARMING JUST AHEAD OF THE COLD FRONT. KEPT HIGHS IN THE LOW/MID
60S. THERE WILL BE MIXING FOR MUCH OF TONIGHT WHICH SHOULD HELP
HOLD UP TEMPERATURES. HOWEVER...THE GRADIENT SHOULD RELAX TOWARD
SUNRISE. USED THE GUIDANCE CONSENSUS FOR THE LOW TEMPERATURE
FORECAST IN THE LOW/MID 30S.
&&
.SHORT TERM /WEDNESDAY THROUGH THURSDAY/...
HIGH PRESSURE WILL BE MOVING INTO THE FORECAST AREA FROM THE WEST
WEDNESDAY. EXPECT CLEAR SKIES. THE TEMPERATURE GUIDANCE WAS
CONSISTENT. THE HIGH WILL BE CENTERED OVER THE AREA WEDNESDAY
NIGHT. THERE MAY BE SOME HIGH CLOUDINESS AS THE UPPER RIDGE
FLATTENS BUT EXPECT THIS CLOUDINESS WILL BE THIN AND STRONG NET
RADIATIONAL COOLING SHOULD OCCUR. WE LEANED TOWARD THE COOLER
TEMPERATURE GUIDANCE. WARMING SHOULD BEGIN THURSDAY AS THE HIGH
SHIFTS OFF THE COAST AND A SOUTHERLY FLOW DEVELOPS. USED THE
GUIDANCE CONSENSUS FOR THE TEMPERATURE FORECAST.
&&
.LONG TERM /THURSDAY NIGHT THROUGH MONDAY/...
RETURN FLOW ON THE WEST SIDE OF HIGH PRESSURE OFF THE SOUTHEAST
COAST WILL BRING INCREASING MOISTURE AND WARMER TEMPERATURES TO
THE AREA INTO THE WEEKEND. RAPIDLY INCREASING MOISTURE WILL LIKELY
RESULT LOW MORNING STRATUS FRIDAY AND SATURDAY. TEMPERATURES WILL
INCREASE TO MUCH ABOVE NORMAL BY SUNDAY WITH MORNING LOWS NEAR 60
AND HIGHS IN THE MID TO UPPER 70S. A COLD FRONT WILL APPROACH THE
AREA FROM THE WEST ON SUNDAY AND CROSS THE AREA SUNDAY NIGHT INTO
MONDAY. WILL INCREASE POPS TO THE 60 TO 70 PERCENT RANGE WITH THE
FRONTAL PASSAGE. WITH WARM MOIST AIR AT LOW LEVELS...A 40 TO 50 KT
LOW LEVEL JET...AND SLIGHTLY UNSTABLE LI VALUES...SOME CONVECTION
IS POSSIBLE WITH THIS FRONTAL PASSAGE. WILL HAVE TO WATCH THIS AS
WE GET CLOSER TO THE EVENT. DRIER AND COLDER AIR WILL MOVE IN
BEHIND THE FRONT MONDAY AFTERNOON INTO TUESDAY.
WHILE THE TREND FOR INCREASING TEMPERATURES AND DEWPOINTS IS HIGH
CONFIDENCE...THE DETAILS ARE TOUGH TO NAIL DOWN DUE TO THE
POTENTIAL FOR MORNING STRATUS ON FRIDAY AND SATURDAY. CONFIDENCE
FOR RAIN WITH THE FRONTAL PASSAGE IS ABOVE AVERAGE.
&&
.AVIATION /18Z TUESDAY THROUGH SUNDAY/...
HIGH CONFIDENCE IN VFR CONDITIONS THROUGH THE FORECAST PERIOD.
DRY AIR MASS IN PLACE FOR CLEAR SKIES. WEST TO SOUTHWEST WINDS
AROUND 10 KNOTS WITH GUST UP TO 20 KNOTS THIS AFTERNOON.
WINDS SHOULD DECREASE BY SUNSET THEN VEER WEST TO NORTHWEST THIS
EVENING AS A COLD FRONT MOVES THROUGH THE TAF SITES.
EXTENDED AVIATION OUTLOOK...INCREASING LOW LEVEL MOISTURE COMBINED
WITH NOCTURNAL COOLING COULD ALLOW MVFR/IFR CIGS/FOG TO DEVELOP
DURING THE LATE NIGHT AND EARLY MORNING HOURS FRIDAY THROUGH SUNDAY.
&&
.CAE WATCHES/WARNINGS/ADVISORIES...
SC...NONE.
GA...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS COLUMBIA SC
1242 PM EST TUE DEC 17 2013
.SYNOPSIS...
HIGH PRESSURE OVER THE SOUTHERN STATES WILL SLIP WESTWARD THIS
AFTERNOON ALLOWING A MOISTURE STARVED COLD FRONT TO CROSS OUR AREA
THIS EVENING. HIGH PRESSURE WILL BUILD ACROSS THE REGION WEDNESDAY
THEN SLIDE OFF THE SOUTHEAST COAST THURSDAY. A SOUTHERLY FLOW WILL
BRING MUCH ABOVE NORMAL TEMPERATURES TO THE AREA FOR THE WEEKEND.
&&
.NEAR TERM /THROUGH TONIGHT/...
HIGH PRESSURE STRETCHED ACROSS THE GULF COAST STATES LATE THIS
MORNING WITH A COLD FRONT EXTENDING FROM PA THROUGH KY TO AR. OUR
AIR MASS REMAINED DRY WITH PWAT LESS THAN 0.50 INCHES. STILL
EXPECT CLEAR SKIES TO HOLD ACROSS THE AREA. THE FRONT WILL MOVE
THROUGH THE FORECAST AREA EARLY TONIGHT.
IT WILL BE WARM AND BREEZY AHEAD OF THE FRONT THIS AFTERNOON. THE
NAM BUFKIT MOMENTUM TRANSFER TOOL SUPPORTS GUSTS AROUND 20 KNOTS.
THE 10Z HRRR INDICATES GUSTS OF 20 TO 25 KNOTS. LEANED TOWARD THE
WARMER TEMPERATURE GUIDANCE THIS AFTERNOON GIVEN DRY AIR MASS AND
WARMING JUST AHEAD OF THE COLD FRONT. KEPT HIGHS IN THE LOW/MID
60S. THERE WILL BE MIXING FOR MUCH OF TONIGHT WHICH SHOULD HELP
HOLD UP TEMPERATURES. HOWEVER... THE GRADIENT SHOULD RELAX TOWARD
SUNRISE. USED THE GUIDANCE CONSENSUS FOR THE LOW TEMPERATURE
FORECAST IN THE LOW/MID 30S.
&&
.SHORT TERM /WEDNESDAY THROUGH THURSDAY/...
HIGH PRESSURE WILL BE MOVING INTO THE FORECAST AREA FROM THE WEST
WEDNESDAY. EXPECT CLEAR SKIES. THE TEMPERATURE GUIDANCE WAS
CONSISTENT. THE HIGH WILL BE CENTERED OVER THE AREA WEDNESDAY
NIGHT. THERE MAY BE SOME HIGH CLOUDINESS AS THE UPPER RIDGE
FLATTENS BUT EXPECT THIS CLOUDINESS WILL BE THIN AND STRONG NET
RADIATIONAL COOLING SHOULD OCCUR. WE LEANED TOWARD THE COOLER
TEMPERATURE GUIDANCE. WARMING SHOULD BEGIN THURSDAY AS THE HIGH
SHIFTS OFF THE COAST AND A SOUTHERLY FLOW DEVELOPS. USED THE
GUIDANCE CONSENSUS FOR THE TEMPERATURE FORECAST.
&&
.LONG TERM /THURSDAY NIGHT THROUGH MONDAY/...
RETURN FLOW ON THE WEST SIDE OF HIGH PRESSURE OFF THE SOUTHEAST
COAST WILL BRING INCREASING MOISTURE AND WARMER TEMPERATURES TO
THE AREA INTO THE WEEKEND. RAPIDLY INCREASING MOISTURE WILL LIKELY
RESULT LOW MORNING STRATUS FRIDAY AND SATURDAY. TEMPERATURES WILL
INCREASE TO MUCH ABOVE NORMAL BY SUNDAY WITH MORNING LOWS NEAR 60
AND HIGHS IN THE MID TO UPPER 70S. A COLD FRONT WILL APPROACH THE
AREA FROM THE WEST ON SUNDAY AND CROSS THE AREA SUNDAY NIGHT INTO
MONDAY. WILL INCREASE POPS TO THE 60 TO 70 PERCENT RANGE WITH THE
FRONTAL PASSAGE. WITH WARM MOIST AIR AT LOW LEVELS...A 40 TO 50 KT
LOW LEVEL JET...AND SLIGHTLY UNSTABLE LI VALUES...SOME CONVECTION
IS POSSIBLE WITH THIS FRONTAL PASSAGE. WILL HAVE TO WATCH THIS AS
WE GET CLOSER TO THE EVENT. DRIER AND COLDER AIR WILL MOVE IN
BEHIND THE FRONT MONDAY AFTERNOON INTO TUESDAY.
WHILE THE TREND FOR INCREASING TEMPERATURES AND DEWPOINTS IS HIGH
CONFIDENCE...THE DETAILS ARE TOUGH TO NAIL DOWN DUE TO THE
POTENTIAL FOR MORNING STRATUS ON FRIDAY AND SATURDAY. CONFIDENCE
FOR RAIN WITH THE FRONTAL PASSAGE IS ABOVE AVERAGE.
&&
.AVIATION /18Z TUESDAY THROUGH SUNDAY/...
HIGH CONFIDENCE IN VFR CONDITIONS THROUGH THE FORECAST PERIOD.
DRY AIR MASS IN PLACE FOR CLEAR SKIES. WINDS BEGINNING TO
INCREASE AT 15Z AS STRONGER WINDS ALOFT MIX DOWN TO THE SURFACE
AHEAD OF AN APPROACHING FRONT. SOME OF THE STRONGER GUSTS MAY
REACH 20 KNOTS LATE THIS MORNING INTO THE AFTERNOON. SOUTHWEST
WINDS THIS AFTERNOON WILL DECREASE BEFORE SHIFTING WEST 18/01Z
THROUGH 18/03Z AS A COLD FRONT MOVES THROUGH THE TAF SITES.
EXTENDED AVIATION OUTLOOK...IFR/MVFR CONDITIONS IN LOW STRATUS
POSSIBLE FRIDAY...SATURDAY...AND SUNDAY MORNINGS.
&&
.CAE WATCHES/WARNINGS/ADVISORIES...
SC...NONE.
GA...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS COLUMBIA SC
1058 AM EST TUE DEC 17 2013
.SYNOPSIS...
HIGH PRESSURE OVER THE SOUTHERN STATES WILL SLIP WESTWARD THIS
AFTERNOON ALLOWING A MOISTURE STARVED COLD FRONT TO CROSS OUR AREA
THIS EVENING. HIGH PRESSURE WILL BUILD ACROSS THE REGION WEDNESDAY
THEN SLIDE OFF THE SOUTHEAST COAST THURSDAY. A SOUTHERLY FLOW WILL
BRING MUCH ABOVE NORMAL TEMPERATURES TO THE AREA FOR THE WEEKEND.
&&
.NEAR TERM /THROUGH TONIGHT/...
HIGH PRESSURE STRETCHED ACROSS THE GULF COAST STATES LATE THIS
MORNING WITH A COLD FRONT EXTENDING FROM PA THROUGH KY TO AR. OUR
AIR MASS REMAINED DRY WITH PWAT LESS THAN 0.50 INCHES. STILL
EXPECT CLEAR SKIES TO HOLD ACROSS THE AREA. THE FRONT WILL MOVE
THROUGH THE FORECAST AREA EARLY TONIGHT.
IT WILL BE WARM AND BREEZY AHEAD OF THE FRONT THIS AFTERNOON. THE
NAM BUFKIT MOMENTUM TRANSFER TOOL SUPPORTS GUSTS AROUND 20 KNOTS.
THE 10Z HRRR INDICATES GUSTS OF 20 TO 25 KNOTS. LEANED TOWARD THE
WARMER TEMPERATURE GUIDANCE THIS AFTERNOON GIVEN DRY AIR MASS AND
WARMING JUST AHEAD OF THE COLD FRONT. KEPT HIGHS IN THE LOW/MID
60S. THERE WILL BE MIXING FOR MUCH OF TONIGHT WHICH SHOULD HELP
HOLD UP TEMPERATURES. HOWEVER... THE GRADIENT SHOULD RELAX TOWARD
SUNRISE. USED THE GUIDANCE CONSENSUS FOR THE LOW TEMPERATURE
FORECAST IN THE LOW/MID 30S.
&&
.SHORT TERM /WEDNESDAY THROUGH THURSDAY/...
HIGH PRESSURE WILL BE MOVING INTO THE FORECAST AREA FROM THE WEST
WEDNESDAY. EXPECT CLEAR SKIES. THE TEMPERATURE GUIDANCE WAS
CONSISTENT. THE HIGH WILL BE CENTERED OVER THE AREA WEDNESDAY
NIGHT. THERE MAY BE SOME HIGH CLOUDINESS AS THE UPPER RIDGE
FLATTENS BUT EXPECT THIS CLOUDINESS WILL BE THIN AND STRONG NET
RADIATIONAL COOLING SHOULD OCCUR. WE LEANED TOWARD THE COOLER
TEMPERATURE GUIDANCE. WARMING SHOULD BEGIN THURSDAY AS THE HIGH
SHIFTS OFF THE COAST AND A SOUTHERLY FLOW DEVELOPS. USED THE
GUIDANCE CONSENSUS FOR THE TEMPERATURE FORECAST.
&&
.LONG TERM /THURSDAY NIGHT THROUGH MONDAY/...
RETURN FLOW ON THE WEST SIDE OF HIGH PRESSURE OFF THE SOUTHEAST
COAST WILL BRING INCREASING MOISTURE AND WARMER TEMPERATURES TO
THE AREA INTO THE WEEKEND. MUCH ABOVE NORMAL TEMPERATURES ARE
EXPECTED BY SUNDAY WITH MORNING LOWS NEAR 60 AND HIGHS IN THE MID
TO UPPER 70S. A COLD FRONT WILL APPROACH THE AREA FROM THE WEST ON
SUNDAY AND CROSS THE AREA SUNDAY NIGHT INTO MONDAY. WILL INCREASE
POPS TO THE 60 TO 70 PERCENT RANGE WITH THE FRONTAL PASSAGE. WITH
WARM MOIST AIR AT LOW LEVELS...A 40 TO 50 KT LOW LEVEL JET...AND
SLIGHTLY UNSTABLE LI VALUES...SOME CONVECTION IS POSSIBLE WITH
THIS FRONTAL PASSAGE. WILL HAVE TO WATCH THIS AS WE GET CLOSER TO
THE EVENT. DRIER AND COLDER AIR WILL MOVE IN BEHIND THE FRONT
MONDAY AFTERNOON INTO TUESDAY
&&
.AVIATION /16Z TUESDAY THROUGH SATURDAY/...
HIGH CONFIDENCE IN VFR CONDITIONS THROUGH THE FORECAST PERIOD.
DRY AIR MASS IN PLACE FOR CLEAR SKIES. WINDS BEGINNING TO
INCREASE AT 15Z AS STRONGER WINDS ALOFT MIX DOWN TO THE SURFACE
AHEAD OF AN APPROACHING FRONT. SOME OF THE STRONGER GUSTS MAY
REACH 20 KNOTS LATE THIS MORNING INTO THE AFTERNOON. SOUTHWEST
WINDS THIS AFTERNOON WILL DECREASE BEFORE SHIFTING WEST 18/01Z
THROUGH 18/03Z AS A COLD FRONT MOVES THROUGH THE TAF SITES.
EXTENDED AVIATION OUTLOOK...NO SIGNIFICANT IMPACTS TO AVIATION
EXPECTED.
&&
.CAE WATCHES/WARNINGS/ADVISORIES...
SC...NONE.
GA...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS COLUMBIA SC
1031 AM EST TUE DEC 17 2013
.SYNOPSIS...
HIGH PRESSURE OVER THE SOUTHERN STATES WILL SLIP WESTWARD THIS
AFTERNOON ALLOWING A MOISTURE STARVED COLD FRONT TO CROSS OUR AREA
THIS EVENING. HIGH PRESSURE WILL BUILD ACROSS THE REGION WEDNESDAY
THEN SLIDE OFF THE SOUTHEAST COAST THURSDAY. A SOUTHERLY FLOW WILL
BRING ABOVE NORMAL TEMPERATURES TO THE AREA FOR THE WEEKEND.
&&
.NEAR TERM /THROUGH TONIGHT/...
HIGH PRESSURE STRETCHED ACROSS THE GULF COAST STATES LATE THIS
MORNING WITH A COLD FRONT EXTENDING FROM PA THROUGH KY TO AR. OUR
AIR MASS REMAINED DRY WITH PWAT LESS THAN 0.50 INCHES. STILL
EXPECT CLEAR SKIES TO HOLD ACROSS THE AREA. THE FRONT WILL MOVE
THROUGH THE FORECAST AREA EARLY TONIGHT.
IT WILL BE WARM AND BREEZY AHEAD OF THE FRONT THIS AFTERNOON. THE
NAM BUFKIT MOMENTUM TRANSFER TOOL SUPPORTS GUSTS AROUND 20 KNOTS.
THE 10Z HRRR INDICATES GUSTS OF 20 TO 25 KNOTS. LEANED TOWARD THE
WARMER TEMPERATURE GUIDANCE THIS AFTERNOON GIVEN DRY AIR MASS AND
WARMING JUST AHEAD OF THE COLD FRONT. KEPT HIGHS IN THE LOW/MID
60S. THERE WILL BE MIXING FOR MUCH OF TONIGHT WHICH SHOULD HELP
HOLD UP TEMPERATURES. HOWEVER... THE GRADIENT SHOULD RELAX TOWARD
SUNRISE. USED THE GUIDANCE CONSENSUS FOR THE LOW TEMPERATURE
FORECAST IN THE LOW/MID 30S.
&&
.SHORT TERM /WEDNESDAY THROUGH THURSDAY/...
HIGH PRESSURE WILL BE MOVING INTO THE FORECAST AREA FROM THE WEST
WEDNESDAY. EXPECT CLEAR SKIES. THE TEMPERATURE GUIDANCE WAS
CONSISTENT. THE HIGH WILL BE CENTERED OVER THE AREA WEDNESDAY
NIGHT. THERE MAY BE SOME HIGH CLOUDINESS AS THE UPPER RIDGE
FLATTENS BUT EXPECT THIS CLOUDINESS WILL BE THIN AND STRONG NET
RADIATIONAL COOLING SHOULD OCCUR. WE LEANED TOWARD THE COOLER
TEMPERATURE GUIDANCE. WARMING SHOULD BEGIN THURSDAY AS THE HIGH
SHIFTS OFF THE COAST AND A SOUTHERLY FLOW DEVELOPS. USED THE
GUIDANCE CONSENSUS FOR THE TEMPERATURE FORECAST.
&&
.LONG TERM /THURSDAY NIGHT THROUGH MONDAY/...
THE OFFSHORE HIGH WILL CIRCULATE INCREASING MOISTURE INTO THE
FORECAST AREA LATE IN THE WEEK AHEAD OF THE SLOW MOVING COLD
FRONT. THERE MAY BE ENOUGH MOISTURE AND ISENTROPIC LIFT FOR
SHOWERS FRIDAY AND SATURDAY BUT WITH THE MAIN FORCING ASSOCIATED
WITH THE FRONT STILL TO THE WEST THE CHANCE SHOULD BE LOW. THE
COLD FRONT APPEARS TO BECOME PARALLEL TO THE UPPER FLOW FRIDAY
NIGHT THROUGH SATURDAY WITH THE FRONT MAKING LITTLE EASTWARD
PROGRESS. THE MEDIUM-RANGE MODELS BRING THE FRONT ACROSS OUR AREA
SUNDAY NIGHT AND MONDAY. THE GFS ENSEMBLE MEANS INDICATE ABOVE
NORMAL POPS SATURDAY THROUGH MONDAY BUT WITH HIGH SPREADS. GIVEN
EXPECTED FRONTAL PASSAGE MONDAY...WE FORECASTED THE HIGHEST POPS
SUNDAY NIGHT INTO MONDAY.
TEMPERATURES WILL BE ABOVE NORMAL THROUGH THE WEEKEND WITH HIGHS IN
THE 70S AND LOWS IN THE UPPER 50S AND LOWER 60S.
&&
.AVIATION /15Z TUESDAY THROUGH SATURDAY/...
HIGH CONFIDENCE IN VFR CONDITIONS THROUGH THE FORECAST PERIOD.
DRY AIR MASS IN PLACE FOR CLEAR SKIES. WINDS BEGINNING TO
INCREASE AT 15Z AS STRONGER WINDS ALOFT MIX DOWN TO THE SURFACE
AHEAD OF AN APPROACHING FRONT. SOME OF THE STRONGER GUSTS MAY
REACH 20 KNOTS LATE THIS MORNING INTO THE AFTERNOON. SOUTHWEST
WINDS THIS AFTERNOON WILL DECREASE BEFORE SHIFTING WEST 18/01Z
THROUGH 18/03Z AS A COLD FRONT MOVES THROUGH THE TAF SITES.
EXTENDED AVIATION OUTLOOK...NO SIGNIFICANT IMPACTS TO AVIATION
EXPECTED.
&&
.CAE WATCHES/WARNINGS/ADVISORIES...
SC...NONE.
GA...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS COLUMBIA SC
639 AM EST TUE DEC 17 2013
.SYNOPSIS...
A PRESSURE RIDGE WILL BE SOUTH OF THE FORECAST AREA TODAY. THE
RIDGE WILL LIMIT MOISTURE AHEAD OF AN APPROACHING COLD FRONT. THE
DRY FRONT WILL MOVE THROUGH THE FORECAST AREA TONIGHT. HIGH
PRESSURE MOVING INTO THE REGION BEHIND THE FRONT WEDNESDAY WILL BE
CENTERED OVER THE AREA WEDNESDAY NIGHT AND OFF THE SOUTHEAST COAST
THURSDAY.
&&
.NEAR TERM /THROUGH TONIGHT/...
THE PRESSURE RIDGE SOUTH OF THE FORECAST AREA WILL BLOCK A RETURN
OF MOISTURE FROM THE GULF OF MEXICO AHEAD OF THE APPROACHING COLD
FRONT. THE FRONT WILL MOVE THROUGH THE FORECAST AREA TONIGHT. IT
WILL BE WARM AND BREEZY AHEAD OF THE FRONT THIS AFTERNOON. THE NAM
BUFKIT MOMENTUM TRANSFER TOOL SUPPORTS GUSTS AROUND 20 KNOTS. THE
07Z HRRR INDICATES GUSTS OF 20 TO 25 KNOTS. LEANED TOWARD THE
WARMER TEMPERATURE GUIDANCE TODAY BECAUSE OF THE DRY AIR MASS AND
WARMING JUST AHEAD OF THE COLD FRONT. THERE WILL BE MIXING FOR
MUCH OF TONIGHT WHICH SHOULD HELP HOLD UP TEMPERATURES. HOWEVER...
THE GRADIENT SHOULD RELAX TOWARD SUNRISE. USED THE GUIDANCE
CONSENSUS FOR THE LOW TEMPERATURE FORECAST.
&&
.SHORT TERM /WEDNESDAY THROUGH THURSDAY/...
HIGH PRESSURE WILL BE MOVING INTO THE FORECAST AREA FROM THE WEST
WEDNESDAY. EXPECT CLEAR SKIES. THE TEMPERATURE GUIDANCE WAS
CONSISTENT. THE HIGH WILL BE CENTERED OVER THE AREA WEDNESDAY
NIGHT. THERE MAY BE SOME HIGH CLOUDINESS AS THE UPPER RIDGE
FLATTENS BUT EXPECT THIS CLOUDINESS WILL BE THIN AND STRONG NET
RADIATIONAL COOLING SHOULD OCCUR. WE LEANED TOWARD THE COOLER
TEMPERATURE GUIDANCE. WARMING SHOULD BEGIN THURSDAY AS THE HIGH
SHIFTS OFF THE COAST AND A SOUTHERLY FLOW DEVELOPS. USED THE
GUIDANCE CONSENSUS FOR THE TEMPERATURE FORECAST.
&&
.LONG TERM /THURSDAY NIGHT THROUGH MONDAY/...
THE OFFSHORE HIGH WILL CIRCULATE INCREASING MOISTURE INTO THE
FORECAST AREA LATE IN THE WEEK AHEAD OF THE SLOW MOVING COLD
FRONT. THERE MAY BE ENOUGH MOISTURE AND ISENTROPIC LIFT FOR
SHOWERS FRIDAY AND SATURDAY BUT WITH THE MAIN FORCING ASSOCIATED
WITH THE FRONT STILL TO THE WEST THE CHANCE SHOULD BE LOW. THE
COLD FRONT APPEARS TO BECOME PARALLEL TO THE UPPER FLOW FRIDAY
NIGHT THROUGH SATURDAY WITH THE FRONT MAKING LITTLE EASTWARD
PROGRESS. THE MEDIUM-RANGE MODELS BRING THE FRONT ACROSS OUR AREA
SUNDAY NIGHT AND MONDAY. THE GFS ENSEMBLE MEANS INDICATE ABOVE
NORMAL POPS SATURDAY THROUGH MONDAY BUT WITH HIGH SPREADS. GIVEN
EXPECTED FRONTAL PASSAGE MONDAY...WE FORECASTED THE HIGHEST POPS
SUNDAY NIGHT INTO MONDAY.
TEMPERATURES WILL BE ABOVE NORMAL THROUGH THE WEEKEND WITH HIGHS IN
THE 70S AND LOWS IN THE UPPER 50S AND LOWER 60S.
&&
.AVIATION /12Z TUESDAY THROUGH SATURDAY/...
HIGH CONFIDENCE IN VFR CONDITIONS THROUGH THE FORECAST PERIOD.
DRY HIGH PRESSURE CONTINUES TO DOMINATE OVER THE AREA. DRY AIR
AND LIGHT WINDS WILL HELP TO LIMIT FOG DEVELOPMENT. WINDS WILL
INCREASE DURING THE DAY AS STRONGER WINDS ALOFT MIX DOWN TO THE
SURFACE AHEAD OF AN APPROACHING FRONT. SOME OF THE STRONGER GUSTS
MAY REACH 20 KNOTS DURING THE LATE MORNING AND EARLY AFTERNOON
HOURS.
EXTENDED AVIATION OUTLOOK...NO SIGNIFICANT IMPACTS TO AVIATION
EXPECTED.
&&
.CAE WATCHES/WARNINGS/ADVISORIES...
SC...NONE.
GA...NONE.
&&
$$
SYNOPSIS...
NEAR TERM...
SHORT TERM...
LONG TERM...
AVIATION...
AREA FORECAST DISCUSSION
NWS COLUMBIA SC
518 AM EST TUE DEC 17 2013
.SYNOPSIS...
A PRESSURE RIDGE WILL BE SOUTH OF THE FORECAST AREA TODAY. THE
RIDGE WILL LIMIT MOISTURE AHEAD OF AN APPROACHING COLD FRONT. THE
DRY FRONT WILL MOVE THROUGH THE FORECAST AREA TONIGHT. HIGH
PRESSURE MOVING INTO THE REGION BEHIND THE FRONT WEDNESDAY WILL BE
CENTERED OVER THE AREA WEDNESDAY NIGHT AND OFF THE SOUTHEAST COAST
THURSDAY.
&&
.NEAR TERM /THROUGH TONIGHT/...
THE PRESSURE RIDGE SOUTH OF THE FORECAST AREA WILL BLOCK A RETURN
OF MOISTURE FROM THE GULF OF MEXICO AHEAD OF THE APPROACHING COLD
FRONT. THE FRONT WILL MOVE THROUGH THE FORECAST AREA TONIGHT. IT
WILL BE WARM AND BREEZY AHEAD OF THE FRONT THIS AFTERNOON. THE NAM
BUFKIT MOMENTUM TRANSFER TOOL SUPPORTS GUSTS AROUND 20 KNOTS. THE
07Z HRRR INDICATES GUSTS OF 20 TO 25 KNOTS. LEANED TOWARD THE
WARMER TEMPERATURE GUIDANCE TODAY BECAUSE OF THE DRY AIR MASS AND
WARMING JUST AHEAD OF THE COLD FRONT. THERE WILL BE MIXING FOR
MUCH OF TONIGHT WHICH SHOULD HELP HOLD UP TEMPERATURES. HOWEVER...
THE GRADIENT SHOULD RELAX TOWARD SUNRISE. USED THE GUIDANCE
CONSENSUS FOR THE LOW TEMPERATURE FORECAST.
&&
.SHORT TERM /WEDNESDAY THROUGH THURSDAY/...
HIGH PRESSURE WILL BE MOVING INTO THE FORECAST AREA FROM THE WEST
WEDNESDAY. EXPECT CLEAR SKIES. THE TEMPERATURE GUIDANCE WAS
CONSISTENT. THE HIGH WILL BE CENTERED OVER THE AREA WEDNESDAY
NIGHT. THERE MAY BE SOME HIGH CLOUDINESS AS THE UPPER RIDGE
FLATTENS BUT EXPECT THIS CLOUDINESS WILL BE THIN AND STRONG NET
RADIATIONAL COOLING SHOULD OCCUR. WE LEANED TOWARD THE COOLER
TEMPERATURE GUIDANCE. WARMING SHOULD BEGIN THURSDAY AS THE HIGH
SHIFTS OFF THE COAST AND A SOUTHERLY FLOW DEVELOPS. USED THE
GUIDANCE CONSENSUS FOR THE TEMPERATURE FORECAST.
&&
.LONG TERM /THURSDAY NIGHT THROUGH MONDAY/...
THE OFFSHORE HIGH WILL CIRCULATE INCREASING MOISTURE INTO THE
FORECAST AREA LATE IN THE WEEK AHEAD OF THE SLOW MOVING COLD
FRONT. THERE MAY BE ENOUGH MOISTURE AND ISENTROPIC LIFT FOR
SHOWERS FRIDAY AND SATURDAY BUT WITH THE MAIN FORCING ASSOCIATED
WITH THE FRONT STILL TO THE WEST THE CHANCE SHOULD BE LOW. THE
COLD FRONT APPEARS TO BECOME PARALLEL TO THE UPPER FLOW FRIDAY
NIGHT THROUGH SATURDAY WITH THE FRONT MAKING LITTLE EASTWARD
PROGRESS. THE MEDIUM-RANGE MODELS BRING THE FRONT ACROSS OUR AREA
SUNDAY NIGHT AND MONDAY. THE GFS ENSEMBLE MEANS INDICATE ABOVE
NORMAL POPS SATURDAY THROUGH MONDAY BUT WITH HIGH SPREADS. GIVEN
EXPECTED FRONTAL PASSAGE MONDAY...WE FORECASTED THE HIGHEST POPS
SUNDAY NIGHT INTO MONDAY.
TEMPERATURES WILL BE ABOVE NORMAL THROUGH THE WEEKEND WITH HIGHS IN
THE 70S AND LOWS IN THE UPPER 50S AND LOWER 60S.
&&
.AVIATION /10Z TUESDAY THROUGH SATURDAY/...
HIGH CONFIDENCE IN VFR CONDITIONS THROUGH THE FORECAST PERIOD.
DRY HIGH PRESSURE CONTINUES TO DOMINATE OVER THE AREA. THE
COMBINATION OF A DRY AIR MASS AND A LOW-LEVEL JET AROUND 25 KNOTS
JET OVERNIGHT WILL KEEP WINDS JUST OFF THE SURFACE UP ENOUGH TO
HELP INHIBIT FOG DEVELOPMENT. LOW LEVEL WIND SHEAR MIGHT BE A
CONCERN TOWARDS 12Z BUT CONFIDENCE OF MEETING THE 30 KNOT
THRESHOLD IS NOT HIGH ENOUGH TO INCLUDE IN THIS FORECAST. WINDS
WILL INCREASE DURING THE DAY TUESDAY AHEAD OF AN APPROACHING
FRONT...AND THERE COULD BE SOME STRONGER GUSTS AROUND 20 KNOTS
DURING THE LATE MORNING AND EARLY AFTERNOON HOURS.
EXTENDED AVIATION OUTLOOK...NO SIGNIFICANT IMPACTS TO AVIATION
EXPECTED.
&&
.CAE WATCHES/WARNINGS/ADVISORIES...
SC...NONE.
GA...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
319 PM CST TUE DEC 17 2013
.DISCUSSION...
328 AM CST
TODAY...
MAIN CONCERNS WILL BE FOCUSED ON THE MID-LVL WAVE THAT IS QUICKLY
SLIDING EAST ACROSS THE WESTERN GREAT LAKES...POSSIBLY BRINGING A
SLUG OF LGT SNOW TO NORTH/NORTHEAST IL AND NORTHWEST IN THIS MORNING
THRU MIDDAY. THEN THE POTENTIAL FOR SOME BLOWING SNOW AS THE
GRADIENT RAMPS UP MIDDAY AND MIXING JUMPS TO ARND 3KFT AGL.
IR IMAGERY SHOWS CONSIDERABLE CLOUD COVER ACROSS THE REGION...AND
SOME COOLING WITH CLOUD TOPS WITH THE WEAK WAVE SLIDING EAST ACROSS
WESTCENTRAL WISC EARLY THIS MORNING. KARX RADAR INDICATES AN AREA OF
RETURNS ACROSS THIS AREA...HOWEVER THE RECENT COUPLE OF HOURS HAVE
INDICATED SOME DOWNWARD TREND IN THE SOUTHERN PORTION OF THIS
PRECIP. SFC OBS ARE NOT INDICATING ANY SNOW IN FAR SOUTHEAST MN AND
HAS TENDED TO BE FOCUSED FURTHER NORTH. BASED ON CURRENT
TRAJECTORY...THE BEST LGT SNOW MAY END UP HOLDING FURTHER NORTH INTO
WISC. BUFR PROFILES HAVE BACKED OFF ON THE OMEGA PLACEMENT...HOWEVER
A HANDFUL OF POINTS CONTINUE TO INDICATE SOME DEGREE OF LIFT THROUGH
THE FAVORED DGZ ARND 12-15Z. DPROG/DT OF THE BUFR SITES ALSO
INDICATES A DOWNWARD TREND...SUPPORTING THE LOWER CONFIDENCE IN SNOW
TOTALS. THE CAVEAT AND CHALLENGE IS THE NARROW CHANNEL OF MOISTURE
THAT STRETCHES WEST AND RECENT RAP GUIDANCE HAS INDICATED AN
ENHANCEMENT TO THIS FEATURE AS IT PIVOTS EAST ACROSS THE CWFA THIS
MORNING.
SNOWFALL RATIOS SHOULD FALL AROUND 20:1...SO RATHER DRY.
BASED ON COBB OUTPUT FROM THESE PROFILES SNOWFALL SHUD GENERALLY
FALL BETWEEN A FEW TENTHS TO 1". COULD SEE AREAS CLOSEST TO THE
WISCONSIN STATELINE PICKING UP SLIGHTLY MORE OR WITHIN A 1-2" RANGE.
THE WAVE WILL REMAIN PROGRESSIVE AND SHUD COME TO AN END BY 15-17Z
FROM WEST TO EAST...AS WIND GUSTS BEGIN TO DEVELOP. ANY FRESH
SNOWFALL SHUD EASILY BLOW AROUND. THIS MAY BE MORE FOCUSED ACROSS
AREAS NORTH OF I-80...AS THE PATCHY DZ EARLY THIS MORNING WILL
MOISTEN UP THE SNOW FURTHER SOUTH AND LIMIT THE ABILITY FOR THE SNOW
TO BLOW AROUND.
TEMPS WILL BEGIN TO REBOUND TDY...AS THE 500MB TROUGH AXIS BEGINS TO
PUSH EAST OF THE WESTERN GREAT LAKES. TEMPS WILL STEADILY WARM INTO
THE UPR 20S TO ARND 30 ACROSS THE SOUTHERN CWFA.
CONFIDENCE IN SNOWFALL...MEDIUM/LOW.
CONFIDENCE IN TEMPS...HIGH.
TONIGHT THROUGH WEDNESDAY...
500MB HEIGHTS BEGIN TO RISE THIS EVENING WITH DIFFLUENT FLOW LIFTING
NORTH FROM THE SFC RIDGE CENTERED ACROSS THE OZARKS. THIS SHUD AID
IN ERODING SOME OF THE CLOUD COVER...AND COULD SEE P-CLOUDY SKIES
FOR A BRIEF PERIOD OVERNIGHT. THEN ANOTHER WEAK MID-LVL WAVE IS
PROGGED TO BUMP INTO THE DIFFLUENT FLOW AND BRING SOME MID-LVL
MOISTURE AND CLOUDS BACK TO THE AREA DURING THE OVERNIGHT HOURS.
500MB FLOW CONTINUES TO EVOLVE INTO A ZONAL SETUP...ALTHOUGH THIS
WILL ONLY BE TEMPORARY THRU WED. SFC RIDGE ACROSS THE OZARKS DRIFTS
EAST TOWARDS THE MID-ATLANTIC/GULF STATES...WITH LLVL FLOW TURNING
SOUTH/SOUTHWEST FOR THE CWFA.
FOR THE FIRST TIME IN SEVERAL DAYS WED MAY SEE THE 850MB 0 DEG
ISOTHERM LIFT OVERHEAD ALONG THE LEADING EDGE OF INCREASED WARM AIR
ADVECTION. THE MID-LVL THERMAL RIDGE CONTINUES TO WARM FURTHER SOUTH
WITH TEMPS RISING TO NEAR 9 DEG C OVER NORTHERN MISSOURI WED AFTN.
GIVEN THE EXPANSIVE SNOW COVER...THE CHALLENGE IS HOW WARM WILL WED
END UP BECOMING. GUIDANCE HAS TRENDED SLIGHTLY COOLER OVER THE PAST
FEW DAYS WITH WED HIGHS. AT THIS TIME THE GENERAL CONSENSUS HAS BEEN
ON TEMPS IN THE LOW 30S ALONG/NORTH OF I-80 AND POINTS SOUTH
POSSIBLY REACHING THE MID 30S.
WITH DEW POINTS PROGGED TO BE RISING TO ARND FREEZING...THE SNOWMELT
RATES WILL RAMP UP. WITH THE ADDED MOISTURE COUPLED WITH A
MOISTENING MID/UPR LVLS AHEAD OF THE NEXT WEATHER SYSTEM...THE
ENVIRONMENT SEEMS PRIMED FOR THE DEVELOPMENT OF PATCHY/AREAS OF FOG.
FREQUENTLY MELTING SNOW CAN PRODUCE SHALLOW DENSE FOG...SO THIS WILL
CONTINUE TO BE THE FOCUS WED NGT.
CONFIDENCE IN TEMPS...MEDIUM.
CONFIDENCE IN FOG DEVELOPING WED NGT...HIGH.
THURSDAY THROUGH SATURDAY...
MID-LVL FLOW CONTINUES TO PROGRESS INTO A SOUTHWEST SETUP WITH A
500MB VORT MAX PUSHING INTO THE FOUR-CORNERS REGION THUR. SFC
RIDGING IN THE LLVLS WILL BE PARKED OVER THE SOUTHEASTERN
CONUS...ALLOWING FOR CONTINUED FEED OF WARM AIR ADVECTING NORTH
THROUGH THE OZARKS INTO THE OHIO VALLEY/GREAT LAKES REGIONS THUR.
GUIDANCE CONTINUES TO FEATURE A WAVE DEVELOPING ALONG THE LEE-SIDE
OF THE ROCKIES THUR...AS A WEAK SFC RIDGE SAGS SOUTH FROM CENTRAL
CANADA INTO THE UPPER MIDWEST AND SHARPENS UP A BAROCLINIC ZONE OVER
THE NORTHERN PLAINS STRETCHING NORTHEAST THROUGH THE UPPER PENINSULA
OF MICHIGAN. THIS WILL LIKELY KEEP THE WARM AIR OVER THE CWFA
THUR...AND ANY PRECIP WILL LIKELY FALL AS LIQUID THUR. AT THE ONSET
THUR MORNING A BRIEF PERIOD OF FZDZ/FZRA MAY OCCUR...HOWEVER THIS
WILL LIKELY BE BRIEF. GUIDANCE HAS TRENDED SLIGHTLY FURTHER SOUTH
WITH THE SFC LOW FOR THUR NIGHT...AS THE 850MB LOW IS PROGGED TO
SLIDE OVER SOUTH CENTRAL WISC.
WITH SOME DEGREE OF UNCERTAINTY REMAINING IN THE PLACEMENT OF THE
SFC LOW...THIS OPENS UP DECREASED CONFIDENCE IN HIGH TEMPS FOR THUR.
A FURTHER NORTH PATH WOULD PROVIDE TEMPS IN THE MID/UPR
30S...MEANWHILE A CORRECTION TO THE SOUTH WOULD KEEP TEMPS ARND 30
TO LOW 30S. FURTHER COMPOUNDING THIS WOULD BE THE THEN POTENTIAL FOR
P-TYPE ISSUES.
THE SFC RIDGE ACROSS THE UPPER MIDWEST SHUD HELP TO PUSH THE
BAROCLINIC BOUNDARY SOUTH FOR FRI...AS THE LOW LIFTS NORTHEAST OF
THE FORECAST AREA. THIS SHUD AID IN COOLER AIR FILTERING IN BEHIND
AND PUSHING DEW POINTS BACK INTO THE 20S. P-TYPE FOR FRI SHUD BE
LIMITED TO RA/SN...AND TRANSITION TO ALL SN BY FRI AFTN/EVE.
500MB VORT MAX ACROSS THE FAR SOUTHWEST CONUS WILL BEGIN TO DIG
SOUTHEAST OF NEW MEXICO...WHICH WILL LIKELY TRANSLATE IN THE
DOWNSTREAM BOUNDARY SAGGING FURTHER SOUTH THROUGH THE OHIO VALLEY
FRI NGT. THEN YET ANOTHER WAVE IS PROGGED TO DEVELOP ACROSS EASTERN
TEXAS AND TAKE A CLASSIC TRAJECTORY TOWARDS THE OHIO VALLEY FOR THE
SECOND HALF OF THE WEEKEND.
CONFIDENCE IN TEMPS...MEDIUM/HIGH.
SUNDAY THROUGH EARLY CHRISTMAS WEEK...
ENSEMBLES INDICATE A SIMILAR COLD SETUP FOR THE SECOND HALF OF THE
WEEKEND INTO EARLY CHRISTMAS WEEK. WESTERN MID-LVL RIDGE MAY BEGIN
TO AMPLIFY FOR EARLY NEXT WEEK...RESULTING IN A DOWNSTREAM TROUGH
POSITIONED OVER THE GREAT LAKES REGION. OPERATIONAL SOLUTIONS
CONTINUE TO POINT TOWARDS A ROBUST WEATHER SYSTEM SUN LIFTING
NORTHEAST ACROSS THE REGION FROM THE SOUTHERN PLAINS/EASTERN
TEXAS...WITH TEMPS COLD ENOUGH TO SUPPORT ALL SNOW FOR THIS EVENT.
THEN ON THE BACKSIDE OF THIS MUCH COLDER AIR POURS BACK INTO THE
CWFA WITH TEMPS ALOFT RETURNING TO -10 TO -14 DEG C AT 850MB FOR
EARLY CHRISTMAS WEEK. THIS WILL KEEP SFC TEMPS IN THE UPPER TEENS TO
LOW 20S.
CONFIDENCE IN SUNDAY SYSTEM...HIGH.
CONFIDENCE IN TEMPS...MEDIUM/HIGH.
BEACHLER
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 20Z...
* PERIODIC MVFR CIGS POSSIBLE LATER THIS AFTERNOON INTO THIS
EVENING
* SLIGHT CHANCE OF -SHSN LATE THIS AFTERNOON/EARLY THIS EVENING
IZZI
//DISCUSSION...UPDATED 18Z...
FIRST DISTURBANCE MOVING EAST OF THE AREA WITH CIGS/VSBYS
IMPROVING TO VFR AND SNOW LIKELY END BY 18Z. STEEPENING LOW AND
MID LEVEL LAPSE RATES EXPECTED THIS AFTERNOON WILL ENCOURAGE
INCREASINGLY GUSTY WEST WINDS THIS AFTERNOON. GIVEN THE STEEP
LAPSE RATES AND ANOTHER WEAK DISTURBANCE UPSTREAM CANNOT
COMPLETELY RULE OUT ANOTHER BRIEF SNOW SHOWER LATE THIS AFTERNOON
INTO EARLY THIS EVENING...THOUGH CHANCES LOOK LOW ENOUGH TO KEEP
IT OUT OF THE TAF. COULD ALSO BE SOME PERIODIC MVFR CIGS THIS
AFTERNOON INTO THE EVENING...THOUGH PROBABLY MORE PREVAILING VFR.
WINDS GRADUALLY DIMINISH TONIGHT AND THEN BEGIN TO BACK TO
SOUTHERLY WEDNESDAY MORNING. SOUTH WINDS WILL INCREASE AND ATTAIN
SOME GUSTINESS UP TO 20-25KT WEDNESDAY AFTERNOON.
IZZI
//ORD AND MDW CONFIDENCE...UPDATED 20Z...
* LOW CONFIDENCE IN A BRIEF SNOW SHOWER LATE THIS
AFTERNOON/EVENING
* LOW-MEDIUM CONFIDENCE IN CIGS REMAINING VFR
* HIGH CONFIDENCE IN REMAINING FORECAST ELEMENTS
IZZI
//OUTLOOK FOR ORD/MDW FOR 00Z THURSDAY-12Z TUESDAY...UPDATED 18Z...
WEDNESDAY NIGHT...IFR/LIFR CIGS PROBABLY DEVELOPING.
THURSDAY...IFR/LIFR LIKELY. CHANCE OF -RA/DZ.
FRIDAY...IFR LIKELY. CHANCE OF -RA/-SN.
SATURDAY...IFR POSSIBLE. CHANCE OF SNOW...MAINLY AT NIGHT.
SUNDAY...IFR POSSIBLE. CHANCE OF SNOW.
MONDAY...MVFR CIGS POSSIBLE.
IZZI
&&
.MARINE...
315 PM CST
WILL LEAVE HEADLINES AS IS THIS EVENING FOR MARGINAL WESTERLY GALES
ON SOUTHERN PART OF THE LAKE...BUT ALLOW EVENING SHIFT TO ASSESS AND
POSSIBLY CANCEL EARLY. SMALL CRAFT ADVISORY FROM WINTHROP HARBOR TO
GARY IS IN GOOD SHAPE. THEN CONCERN SHIFTS TO LIKELY SOUTH-SOUTHWEST
GALES ON WEDNESDAY AFTERNOON INTO WEDNESDAY NIGHT COURTESY OF STRONG
PRESSURE FALLS AND A TIGHT PRESSURE GRADIENT WITH LOW PRESSURE
APPROACHING FROM THE WEST AND HIGH PRESSURE OVER THE OH VALLEY. HAVE
HIGHEST CONFIDENCE IN GALES DEVELOPING ON THE SOUTH HALF WITH
SOMEWHAT LESSER CONFIDENCE ON THE NORTH IN TERMS OF DURATION AND
SEEING PREVAILING GALES...BUT FELT IT WAS PRUDENT TO ISSUE A GALE
WATCH FOR THE ENTIRE OPEN LAKE FROM 21Z WEDS TO 10Z THURS. WILL
LIKELY NEED A SCA FOR THE NEAR SHORE ZONES DURING THIS TIME. AFTER
GALE IS DROPPED FOR GARY TO MI CITY NSH ZONE THIS EVENING...ITS
POSSIBLE THAT THE SCA MAY JUST BE EXTENDED THROUGH TOMORROW NIGHT
FOR THIS ZONE.
A COLD FRONT WILL THEN SHIFT SOUTH DOWN THE LAKE THURSDAY THROUGH
THURSDAY NIGHT..WITH LARGE VARIANCE AMONGST FORECAST GUIDANCE IN
THE TIMING OF THIS FRONT. HAVE FAVORED A SLOWER MOVEMENT OF THE
FRONT DOWN THE SOUTHERN PORTION OF THE LAKE WITH THIS FORECAST
ISSUANCE. THERE IS SOME POTENTIAL FOR FAIRLY STRONG BUT LIKELY
SUB-GALE NORTHERLY WINDS BEHIND THE FRONT. WEAK HIGH PRESSURE WILL
THEN RESULT IN LIGHTER WINDS FRIDAY NIGHT INTO SATURDAY.
HOWEVER...ANOTHER STRONGER SYSTEM THEN LOOKS TO MOVE FROM THE OHIO
VALLEY TOWARD THE CENTRAL LAKES LATE SATURDAY INTO SUNDAY. THE
POTENTIAL CERTAINLY EXISTS FOR NORTHEAST TO NORTH GALES IN
ASSOCIATION WITH THIS SYSTEM DEPENDING ON ITS ULTIMATE TRACK AND
STRENGTH...BUT FOR NOW HAVE INCREASED WINDS TO 30 KT.
RC
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...GALE WARNING...LMZ080-LMZ567-LMZ669-LMZ671-LMZ673-LMZ675-LMZ744-
LMZ745-LMZ777-LMZ779-LMZ868-LMZ870-LMZ872-LMZ874-LMZ876-
LMZ878 UNTIL 9 PM TUESDAY.
GALE WATCH...LMZ080-LMZ261-LMZ362-LMZ364-LMZ366-LMZ563-LMZ565-
LMZ567-LMZ669-LMZ671-LMZ673-LMZ675-LMZ777-LMZ779-LMZ868-
LMZ870-LMZ872-LMZ874-LMZ876-LMZ878...3 PM WEDNESDAY TO 4 AM
THURSDAY.
SMALL CRAFT ADVISORY...NEARSHORE WINTHROP HARBOR TO GARY IN UNTIL
MIDNIGHT WEDNESDAY.
&&
$$
VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)
FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/US.NATIONALWEATHERSERVICE.CHICAGO.GOV
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
152 PM CST TUE DEC 17 2013
.DISCUSSION...
328 AM CST
TODAY...
MAIN CONCERNS WILL BE FOCUSED ON THE MID-LVL WAVE THAT IS QUICKLY
SLIDING EAST ACROSS THE WESTERN GREAT LAKES...POSSIBLY BRINGING A
SLUG OF LGT SNOW TO NORTH/NORTHEAST IL AND NORTHWEST IN THIS MORNING
THRU MIDDAY. THEN THE POTENTIAL FOR SOME BLOWING SNOW AS THE
GRADIENT RAMPS UP MIDDAY AND MIXING JUMPS TO ARND 3KFT AGL.
IR IMAGERY SHOWS CONSIDERABLE CLOUD COVER ACROSS THE REGION...AND
SOME COOLING WITH CLOUD TOPS WITH THE WEAK WAVE SLIDING EAST ACROSS
WESTCENTRAL WISC EARLY THIS MORNING. KARX RADAR INDICATES AN AREA OF
RETURNS ACROSS THIS AREA...HOWEVER THE RECENT COUPLE OF HOURS HAVE
INDICATED SOME DOWNWARD TREND IN THE SOUTHERN PORTION OF THIS
PRECIP. SFC OBS ARE NOT INDICATING ANY SNOW IN FAR SOUTHEAST MN AND
HAS TENDED TO BE FOCUSED FURTHER NORTH. BASED ON CURRENT
TRAJECTORY...THE BEST LGT SNOW MAY END UP HOLDING FURTHER NORTH INTO
WISC. BUFR PROFILES HAVE BACKED OFF ON THE OMEGA PLACEMENT...HOWEVER
A HANDFUL OF POINTS CONTINUE TO INDICATE SOME DEGREE OF LIFT THROUGH
THE FAVORED DGZ ARND 12-15Z. DPROG/DT OF THE BUFR SITES ALSO
INDICATES A DOWNWARD TREND...SUPPORTING THE LOWER CONFIDENCE IN SNOW
TOTALS. THE CAVEAT AND CHALLENGE IS THE NARROW CHANNEL OF MOISTURE
THAT STRETCHES WEST AND RECENT RAP GUIDANCE HAS INDICATED AN
ENHANCEMENT TO THIS FEATURE AS IT PIVOTS EAST ACROSS THE CWFA THIS
MORNING.
SNOWFALL RATIOS SHOULD FALL AROUND 20:1...SO RATHER DRY.
BASED ON COBB OUTPUT FROM THESE PROFILES SNOWFALL SHUD GENERALLY
FALL BETWEEN A FEW TENTHS TO 1". COULD SEE AREAS CLOSEST TO THE
WISCONSIN STATELINE PICKING UP SLIGHTLY MORE OR WITHIN A 1-2" RANGE.
THE WAVE WILL REMAIN PROGRESSIVE AND SHUD COME TO AN END BY 15-17Z
FROM WEST TO EAST...AS WIND GUSTS BEGIN TO DEVELOP. ANY FRESH
SNOWFALL SHUD EASILY BLOW AROUND. THIS MAY BE MORE FOCUSED ACROSS
AREAS NORTH OF I-80...AS THE PATCHY DZ EARLY THIS MORNING WILL
MOISTEN UP THE SNOW FURTHER SOUTH AND LIMIT THE ABILITY FOR THE SNOW
TO BLOW AROUND.
TEMPS WILL BEGIN TO REBOUND TDY...AS THE 500MB TROUGH AXIS BEGINS TO
PUSH EAST OF THE WESTERN GREAT LAKES. TEMPS WILL STEADILY WARM INTO
THE UPR 20S TO ARND 30 ACROSS THE SOUTHERN CWFA.
CONFIDENCE IN SNOWFALL...MEDIUM/LOW.
CONFIDENCE IN TEMPS...HIGH.
TONIGHT THROUGH WEDNESDAY...
500MB HEIGHTS BEGIN TO RISE THIS EVENING WITH DIFFLUENT FLOW LIFTING
NORTH FROM THE SFC RIDGE CENTERED ACROSS THE OZARKS. THIS SHUD AID
IN ERODING SOME OF THE CLOUD COVER...AND COULD SEE P-CLOUDY SKIES
FOR A BRIEF PERIOD OVERNIGHT. THEN ANOTHER WEAK MID-LVL WAVE IS
PROGGED TO BUMP INTO THE DIFFLUENT FLOW AND BRING SOME MID-LVL
MOISTURE AND CLOUDS BACK TO THE AREA DURING THE OVERNIGHT HOURS.
500MB FLOW CONTINUES TO EVOLVE INTO A ZONAL SETUP...ALTHOUGH THIS
WILL ONLY BE TEMPORARY THRU WED. SFC RIDGE ACROSS THE OZARKS DRIFTS
EAST TOWARDS THE MID-ATLANTIC/GULF STATES...WITH LLVL FLOW TURNING
SOUTH/SOUTHWEST FOR THE CWFA.
FOR THE FIRST TIME IN SEVERAL DAYS WED MAY SEE THE 850MB 0 DEG
ISOTHERM LIFT OVERHEAD ALONG THE LEADING EDGE OF INCREASED WARM AIR
ADVECTION. THE MID-LVL THERMAL RIDGE CONTINUES TO WARM FURTHER SOUTH
WITH TEMPS RISING TO NEAR 9 DEG C OVER NORTHERN MISSOURI WED AFTN.
GIVEN THE EXPANSIVE SNOW COVER...THE CHALLENGE IS HOW WARM WILL WED
END UP BECOMING. GUIDANCE HAS TRENDED SLIGHTLY COOLER OVER THE PAST
FEW DAYS WITH WED HIGHS. AT THIS TIME THE GENERAL CONSENSUS HAS BEEN
ON TEMPS IN THE LOW 30S ALONG/NORTH OF I-80 AND POINTS SOUTH
POSSIBLY REACHING THE MID 30S.
WITH DEW POINTS PROGGED TO BE RISING TO ARND FREEZING...THE SNOWMELT
RATES WILL RAMP UP. WITH THE ADDED MOISTURE COUPLED WITH A
MOISTENING MID/UPR LVLS AHEAD OF THE NEXT WEATHER SYSTEM...THE
ENVIRONMENT SEEMS PRIMED FOR THE DEVELOPMENT OF PATCHY/AREAS OF FOG.
FREQUENTLY MELTING SNOW CAN PRODUCE SHALLOW DENSE FOG...SO THIS WILL
CONTINUE TO BE THE FOCUS WED NGT.
CONFIDENCE IN TEMPS...MEDIUM.
CONFIDENCE IN FOG DEVELOPING WED NGT...HIGH.
THURSDAY THROUGH SATURDAY...
MID-LVL FLOW CONTINUES TO PROGRESS INTO A SOUTHWEST SETUP WITH A
500MB VORT MAX PUSHING INTO THE FOUR-CORNERS REGION THUR. SFC
RIDGING IN THE LLVLS WILL BE PARKED OVER THE SOUTHEASTERN
CONUS...ALLOWING FOR CONTINUED FEED OF WARM AIR ADVECTING NORTH
THROUGH THE OZARKS INTO THE OHIO VALLEY/GREAT LAKES REGIONS THUR.
GUIDANCE CONTINUES TO FEATURE A WAVE DEVELOPING ALONG THE LEE-SIDE
OF THE ROCKIES THUR...AS A WEAK SFC RIDGE SAGS SOUTH FROM CENTRAL
CANADA INTO THE UPPER MIDWEST AND SHARPENS UP A BAROCLINIC ZONE OVER
THE NORTHERN PLAINS STRETCHING NORTHEAST THROUGH THE UPPER PENINSULA
OF MICHIGAN. THIS WILL LIKELY KEEP THE WARM AIR OVER THE CWFA
THUR...AND ANY PRECIP WILL LIKELY FALL AS LIQUID THUR. AT THE ONSET
THUR MORNING A BRIEF PERIOD OF FZDZ/FZRA MAY OCCUR...HOWEVER THIS
WILL LIKELY BE BRIEF. GUIDANCE HAS TRENDED SLIGHTLY FURTHER SOUTH
WITH THE SFC LOW FOR THUR NIGHT...AS THE 850MB LOW IS PROGGED TO
SLIDE OVER SOUTH CENTRAL WISC.
WITH SOME DEGREE OF UNCERTAINTY REMAINING IN THE PLACEMENT OF THE
SFC LOW...THIS OPENS UP DECREASED CONFIDENCE IN HIGH TEMPS FOR THUR.
A FURTHER NORTH PATH WOULD PROVIDE TEMPS IN THE MID/UPR
30S...MEANWHILE A CORRECTION TO THE SOUTH WOULD KEEP TEMPS ARND 30
TO LOW 30S. FURTHER COMPOUNDING THIS WOULD BE THE THEN POTENTIAL FOR
P-TYPE ISSUES.
THE SFC RIDGE ACROSS THE UPPER MIDWEST SHUD HELP TO PUSH THE
BAROCLINIC BOUNDARY SOUTH FOR FRI...AS THE LOW LIFTS NORTHEAST OF
THE FORECAST AREA. THIS SHUD AID IN COOLER AIR FILTERING IN BEHIND
AND PUSHING DEW POINTS BACK INTO THE 20S. P-TYPE FOR FRI SHUD BE
LIMITED TO RA/SN...AND TRANSITION TO ALL SN BY FRI AFTN/EVE.
500MB VORT MAX ACROSS THE FAR SOUTHWEST CONUS WILL BEGIN TO DIG
SOUTHEAST OF NEW MEXICO...WHICH WILL LIKELY TRANSLATE IN THE
DOWNSTREAM BOUNDARY SAGGING FURTHER SOUTH THROUGH THE OHIO VALLEY
FRI NGT. THEN YET ANOTHER WAVE IS PROGGED TO DEVELOP ACROSS EASTERN
TEXAS AND TAKE A CLASSIC TRAJECTORY TOWARDS THE OHIO VALLEY FOR THE
SECOND HALF OF THE WEEKEND.
CONFIDENCE IN TEMPS...MEDIUM/HIGH.
SUNDAY THROUGH EARLY CHRISTMAS WEEK...
ENSEMBLES INDICATE A SIMILAR COLD SETUP FOR THE SECOND HALF OF THE
WEEKEND INTO EARLY CHRISTMAS WEEK. WESTERN MID-LVL RIDGE MAY BEGIN
TO AMPLIFY FOR EARLY NEXT WEEK...RESULTING IN A DOWNSTREAM TROUGH
POSITIONED OVER THE GREAT LAKES REGION. OPERATIONAL SOLUTIONS
CONTINUE TO POINT TOWARDS A ROBUST WEATHER SYSTEM SUN LIFTING
NORTHEAST ACROSS THE REGION FROM THE SOUTHERN PLAINS/EASTERN
TEXAS...WITH TEMPS COLD ENOUGH TO SUPPORT ALL SNOW FOR THIS EVENT.
THEN ON THE BACKSIDE OF THIS MUCH COLDER AIR POURS BACK INTO THE
CWFA WITH TEMPS ALOFT RETURNING TO -10 TO -14 DEG C AT 850MB FOR
EARLY CHRISTMAS WEEK. THIS WILL KEEP SFC TEMPS IN THE UPPER TEENS TO
LOW 20S.
CONFIDENCE IN SUNDAY SYSTEM...HIGH.
CONFIDENCE IN TEMPS...MEDIUM/HIGH.
BEACHLER
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 20Z...
* PERIODIC MVFR CIGS POSSIBLE LATER THIS AFTERNOON INTO THIS
EVENING
* SLIGHT CHANCE OF -SHSN LATE THIS AFTERNOON/EARLY THIS EVENING
IZZI
//DISCUSSION...UPDATED 18Z...
FIRST DISTURBANCE MOVING EAST OF THE AREA WITH CIGS/VSBYS
IMPROVING TO VFR AND SNOW LIKELY END BY 18Z. STEEPENING LOW AND
MID LEVEL LAPSE RATES EXPECTED THIS AFTERNOON WILL ENCOURAGE
INCREASINGLY GUSTY WEST WINDS THIS AFTERNOON. GIVEN THE STEEP
LAPSE RATES AND ANOTHER WEAK DISTURBANCE UPSTREAM CANNOT
COMPLETELY RULE OUT ANOTHER BRIEF SNOW SHOWER LATE THIS AFTERNOON
INTO EARLY THIS EVENING...THOUGH CHANCES LOOK LOW ENOUGH TO KEEP
IT OUT OF THE TAF. COULD ALSO BE SOME PERIODIC MVFR CIGS THIS
AFTERNOON INTO THE EVENING...THOUGH PROBABLY MORE PREVAILING VFR.
WINDS GRADUALLY DIMINISH TONIGHT AND THEN BEGIN TO BACK TO
SOUTHERLY WEDNESDAY MORNING. SOUTH WINDS WILL INCREASE AND ATTAIN
SOME GUSTINESS UP TO 20-25KT WEDNESDAY AFTERNOON.
IZZI
//ORD AND MDW CONFIDENCE...UPDATED 20Z...
* LOW CONFIDENCE IN A BRIEF SNOW SHOWER LATE THIS
AFTERNOON/EVENING
* LOW-MEDIUM CONFIDENCE IN CIGS REMAINING VFR
* HIGH CONFIDENCE IN REMAINING FORECAST ELEMENTS
IZZI
//OUTLOOK FOR ORD/MDW FOR 00Z THURSDAY-12Z TUESDAY...UPDATED 18Z...
WEDNESDAY NIGHT...IFR/LIFR CIGS PROBABLY DEVELOPING.
THURSDAY...IFR/LIFR LIKELY. CHANCE OF -RA/DZ.
FRIDAY...IFR LIKELY. CHANCE OF -RA/-SN.
SATURDAY...IFR POSSIBLE. CHANCE OF SNOW...MAINLY AT NIGHT.
SUNDAY...IFR POSSIBLE. CHANCE OF SNOW.
MONDAY...MVFR CIGS POSSIBLE.
IZZI
&&
.MARINE...
306 AM CST
FIRST OF ALL MADE NO CHANGES TO THE ONGOING HEADLINES AS THEY ALL
SEEM ON TRACK. A SMALL CRAFT ADVISORY WILL BE NEEDED FOR THE INDIANA
NEARSHORE WATERS AFTER THE GALE WARNING DUE TO LINGERING HAZARDOUS
WAVES.
LOW PRESSURE IS OVER ONTARIO AND IT WILL SLIDE TO THE EAST
TODAY...WHILE ITS COLD FRONT PASSES OVER THE LAKE THIS AFTERNOON.
AT THE SAME TIME HIGH PRESSURE BUILDS OVER THE CENTRAL PLAINS. THIS
WILL TIGHTEN THE PRESSURE GRADIENT OVER THE SOUTHERN END OF THE
LAKE...RESULTING IN LOW END GALES FORMING THIS MORNING THROUGH EARLY
THIS EVENING. WEST WINDS DIMINISH TO ARND 20 KT BY WEDNESDAY
MORNING AS HIGH PRESSURE PASSES TO THE SOUTH. WINDS PICK BACK UP ON
THE BACKSIDE OF THE HIGH LATE WEDNESDAY AFTERNOON INTO WEDNESDAY
EVENING. A BRIEF PERIOD OF SW GALES TO 35 KT IS POSSIBLE DURING
THAT TIME. A SMALL CRAFT ADVISORY WILL LIKELY BE NEEDED AS WELL FOR
WEDNESDAY AFTERNOON AND EVENING. WINDS WEAKEN WEDNESDAY NIGHT AS A
TROUGH OF LOW PRESSURE SITS OVER THE LAKE WEDNESDAY NIGHT THROUGH
THURSDAY. THE NEXT WEAK LOW MOVES OVER THE LAKE THURSDAY NIGHT
BEFORE SHIFTING EAST ON FRIDAY. WINDS TURN LIGHT AND VARIABLE
BEHIND THE LOW ON SATURDAY...BUT THEN TURN NORTH AND STRENGTHEN
SATURDAY NIGHT INTO SUNDAY IN RESPONSE TO THE NEXT SYSTEM. GUIDANCE
FEATURES ANOTHER LOW PUSHING UP THE OHIO RIVER VALLEY SATURDAY NIGHT
INTO SUNDAY WITH HIGH PRESSURE BUILDING DOWN THE PLAINS.
JEE
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...GALE WARNING...LMZ080-LMZ567-LMZ669-LMZ671-LMZ673-LMZ675-LMZ744-
LMZ745-LMZ777-LMZ779-LMZ868-LMZ870-LMZ872-LMZ874-LMZ876-
LMZ878 UNTIL 9 PM TUESDAY.
SMALL CRAFT ADVISORY...NEARSHORE WINTHROP HARBOR TO GARY IN UNTIL
MIDNIGHT WEDNESDAY.
&&
$$
VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)
FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/US.NATIONALWEATHERSERVICE.CHICAGO.GOV
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
1132 AM CST TUE DEC 17 2013
.DISCUSSION...
328 AM CST
TODAY...
MAIN CONCERNS WILL BE FOCUSED ON THE MID-LVL WAVE THAT IS QUICKLY
SLIDING EAST ACROSS THE WESTERN GREAT LAKES...POSSIBLY BRINGING A
SLUG OF LGT SNOW TO NORTH/NORTHEAST IL AND NORTHWEST IN THIS MORNING
THRU MIDDAY. THEN THE POTENTIAL FOR SOME BLOWING SNOW AS THE
GRADIENT RAMPS UP MIDDAY AND MIXING JUMPS TO ARND 3KFT AGL.
IR IMAGERY SHOWS CONSIDERABLE CLOUD COVER ACROSS THE REGION...AND
SOME COOLING WITH CLOUD TOPS WITH THE WEAK WAVE SLIDING EAST ACROSS
WESTCENTRAL WISC EARLY THIS MORNING. KARX RADAR INDICATES AN AREA OF
RETURNS ACROSS THIS AREA...HOWEVER THE RECENT COUPLE OF HOURS HAVE
INDICATED SOME DOWNWARD TREND IN THE SOUTHERN PORTION OF THIS
PRECIP. SFC OBS ARE NOT INDICATING ANY SNOW IN FAR SOUTHEAST MN AND
HAS TENDED TO BE FOCUSED FURTHER NORTH. BASED ON CURRENT
TRAJECTORY...THE BEST LGT SNOW MAY END UP HOLDING FURTHER NORTH INTO
WISC. BUFR PROFILES HAVE BACKED OFF ON THE OMEGA PLACEMENT...HOWEVER
A HANDFUL OF POINTS CONTINUE TO INDICATE SOME DEGREE OF LIFT THROUGH
THE FAVORED DGZ ARND 12-15Z. DPROG/DT OF THE BUFR SITES ALSO
INDICATES A DOWNWARD TREND...SUPPORTING THE LOWER CONFIDENCE IN SNOW
TOTALS. THE CAVEAT AND CHALLENGE IS THE NARROW CHANNEL OF MOISTURE
THAT STRETCHES WEST AND RECENT RAP GUIDANCE HAS INDICATED AN
ENHANCEMENT TO THIS FEATURE AS IT PIVOTS EAST ACROSS THE CWFA THIS
MORNING.
SNOWFALL RATIOS SHOULD FALL AROUND 20:1...SO RATHER DRY.
BASED ON COBB OUTPUT FROM THESE PROFILES SNOWFALL SHUD GENERALLY
FALL BETWEEN A FEW TENTHS TO 1". COULD SEE AREAS CLOSEST TO THE
WISCONSIN STATELINE PICKING UP SLIGHTLY MORE OR WITHIN A 1-2" RANGE.
THE WAVE WILL REMAIN PROGRESSIVE AND SHUD COME TO AN END BY 15-17Z
FROM WEST TO EAST...AS WIND GUSTS BEGIN TO DEVELOP. ANY FRESH
SNOWFALL SHUD EASILY BLOW AROUND. THIS MAY BE MORE FOCUSED ACROSS
AREAS NORTH OF I-80...AS THE PATCHY DZ EARLY THIS MORNING WILL
MOISTEN UP THE SNOW FURTHER SOUTH AND LIMIT THE ABILITY FOR THE SNOW
TO BLOW AROUND.
TEMPS WILL BEGIN TO REBOUND TDY...AS THE 500MB TROUGH AXIS BEGINS TO
PUSH EAST OF THE WESTERN GREAT LAKES. TEMPS WILL STEADILY WARM INTO
THE UPR 20S TO ARND 30 ACROSS THE SOUTHERN CWFA.
CONFIDENCE IN SNOWFALL...MEDIUM/LOW.
CONFIDENCE IN TEMPS...HIGH.
TONIGHT THROUGH WEDNESDAY...
500MB HEIGHTS BEGIN TO RISE THIS EVENING WITH DIFFLUENT FLOW LIFTING
NORTH FROM THE SFC RIDGE CENTERED ACROSS THE OZARKS. THIS SHUD AID
IN ERODING SOME OF THE CLOUD COVER...AND COULD SEE P-CLOUDY SKIES
FOR A BRIEF PERIOD OVERNIGHT. THEN ANOTHER WEAK MID-LVL WAVE IS
PROGGED TO BUMP INTO THE DIFFLUENT FLOW AND BRING SOME MID-LVL
MOISTURE AND CLOUDS BACK TO THE AREA DURING THE OVERNIGHT HOURS.
500MB FLOW CONTINUES TO EVOLVE INTO A ZONAL SETUP...ALTHOUGH THIS
WILL ONLY BE TEMPORARY THRU WED. SFC RIDGE ACROSS THE OZARKS DRIFTS
EAST TOWARDS THE MID-ATLANTIC/GULF STATES...WITH LLVL FLOW TURNING
SOUTH/SOUTHWEST FOR THE CWFA.
FOR THE FIRST TIME IN SEVERAL DAYS WED MAY SEE THE 850MB 0 DEG
ISOTHERM LIFT OVERHEAD ALONG THE LEADING EDGE OF INCREASED WARM AIR
ADVECTION. THE MID-LVL THERMAL RIDGE CONTINUES TO WARM FURTHER SOUTH
WITH TEMPS RISING TO NEAR 9 DEG C OVER NORTHERN MISSOURI WED AFTN.
GIVEN THE EXPANSIVE SNOW COVER...THE CHALLENGE IS HOW WARM WILL WED
END UP BECOMING. GUIDANCE HAS TRENDED SLIGHTLY COOLER OVER THE PAST
FEW DAYS WITH WED HIGHS. AT THIS TIME THE GENERAL CONSENSUS HAS BEEN
ON TEMPS IN THE LOW 30S ALONG/NORTH OF I-80 AND POINTS SOUTH
POSSIBLY REACHING THE MID 30S.
WITH DEW POINTS PROGGED TO BE RISING TO ARND FREEZING...THE SNOWMELT
RATES WILL RAMP UP. WITH THE ADDED MOISTURE COUPLED WITH A
MOISTENING MID/UPR LVLS AHEAD OF THE NEXT WEATHER SYSTEM...THE
ENVIRONMENT SEEMS PRIMED FOR THE DEVELOPMENT OF PATCHY/AREAS OF FOG.
FREQUENTLY MELTING SNOW CAN PRODUCE SHALLOW DENSE FOG...SO THIS WILL
CONTINUE TO BE THE FOCUS WED NGT.
CONFIDENCE IN TEMPS...MEDIUM.
CONFIDENCE IN FOG DEVELOPING WED NGT...HIGH.
THURSDAY THROUGH SATURDAY...
MID-LVL FLOW CONTINUES TO PROGRESS INTO A SOUTHWEST SETUP WITH A
500MB VORT MAX PUSHING INTO THE FOUR-CORNERS REGION THUR. SFC
RIDGING IN THE LLVLS WILL BE PARKED OVER THE SOUTHEASTERN
CONUS...ALLOWING FOR CONTINUED FEED OF WARM AIR ADVECTING NORTH
THROUGH THE OZARKS INTO THE OHIO VALLEY/GREAT LAKES REGIONS THUR.
GUIDANCE CONTINUES TO FEATURE A WAVE DEVELOPING ALONG THE LEE-SIDE
OF THE ROCKIES THUR...AS A WEAK SFC RIDGE SAGS SOUTH FROM CENTRAL
CANADA INTO THE UPPER MIDWEST AND SHARPENS UP A BAROCLINIC ZONE OVER
THE NORTHERN PLAINS STRETCHING NORTHEAST THROUGH THE UPPER PENINSULA
OF MICHIGAN. THIS WILL LIKELY KEEP THE WARM AIR OVER THE CWFA
THUR...AND ANY PRECIP WILL LIKELY FALL AS LIQUID THUR. AT THE ONSET
THUR MORNING A BRIEF PERIOD OF FZDZ/FZRA MAY OCCUR...HOWEVER THIS
WILL LIKELY BE BRIEF. GUIDANCE HAS TRENDED SLIGHTLY FURTHER SOUTH
WITH THE SFC LOW FOR THUR NIGHT...AS THE 850MB LOW IS PROGGED TO
SLIDE OVER SOUTH CENTRAL WISC.
WITH SOME DEGREE OF UNCERTAINTY REMAINING IN THE PLACEMENT OF THE
SFC LOW...THIS OPENS UP DECREASED CONFIDENCE IN HIGH TEMPS FOR THUR.
A FURTHER NORTH PATH WOULD PROVIDE TEMPS IN THE MID/UPR
30S...MEANWHILE A CORRECTION TO THE SOUTH WOULD KEEP TEMPS ARND 30
TO LOW 30S. FURTHER COMPOUNDING THIS WOULD BE THE THEN POTENTIAL FOR
P-TYPE ISSUES.
THE SFC RIDGE ACROSS THE UPPER MIDWEST SHUD HELP TO PUSH THE
BAROCLINIC BOUNDARY SOUTH FOR FRI...AS THE LOW LIFTS NORTHEAST OF
THE FORECAST AREA. THIS SHUD AID IN COOLER AIR FILTERING IN BEHIND
AND PUSHING DEW POINTS BACK INTO THE 20S. P-TYPE FOR FRI SHUD BE
LIMITED TO RA/SN...AND TRANSITION TO ALL SN BY FRI AFTN/EVE.
500MB VORT MAX ACROSS THE FAR SOUTHWEST CONUS WILL BEGIN TO DIG
SOUTHEAST OF NEW MEXICO...WHICH WILL LIKELY TRANSLATE IN THE
DOWNSTREAM BOUNDARY SAGGING FURTHER SOUTH THROUGH THE OHIO VALLEY
FRI NGT. THEN YET ANOTHER WAVE IS PROGGED TO DEVELOP ACROSS EASTERN
TEXAS AND TAKE A CLASSIC TRAJECTORY TOWARDS THE OHIO VALLEY FOR THE
SECOND HALF OF THE WEEKEND.
CONFIDENCE IN TEMPS...MEDIUM/HIGH.
SUNDAY THROUGH EARLY CHRISTMAS WEEK...
ENSEMBLES INDICATE A SIMILAR COLD SETUP FOR THE SECOND HALF OF THE
WEEKEND INTO EARLY CHRISTMAS WEEK. WESTERN MID-LVL RIDGE MAY BEGIN
TO AMPLIFY FOR EARLY NEXT WEEK...RESULTING IN A DOWNSTREAM TROUGH
POSITIONED OVER THE GREAT LAKES REGION. OPERATIONAL SOLUTIONS
CONTINUE TO POINT TOWARDS A ROBUST WEATHER SYSTEM SUN LIFTING
NORTHEAST ACROSS THE REGION FROM THE SOUTHERN PLAINS/EASTERN
TEXAS...WITH TEMPS COLD ENOUGH TO SUPPORT ALL SNOW FOR THIS EVENT.
THEN ON THE BACKSIDE OF THIS MUCH COLDER AIR POURS BACK INTO THE
CWFA WITH TEMPS ALOFT RETURNING TO -10 TO -14 DEG C AT 850MB FOR
EARLY CHRISTMAS WEEK. THIS WILL KEEP SFC TEMPS IN THE UPPER TEENS TO
LOW 20S.
CONFIDENCE IN SUNDAY SYSTEM...HIGH.
CONFIDENCE IN TEMPS...MEDIUM/HIGH.
BEACHLER
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 18Z...
* PERIODIC MVFR CIGS POSSIBLE LATE THIS AFTERNOON INTO THIS EVENING
* SLIGHT CHANCE OF -SHSN LATE THIS AFTERNOON/EARLY THIS EVENING
IZZI
//DISCUSSION...UPDATED 18Z...
FIRST DISTURBANCE MOVING EAST OF THE AREA WITH CIGS/VSBYS
IMPROVING TO VFR AND SNOW LIKELY END BY 18Z. STEEPENING LOW AND
MID LEVEL LAPSE RATES EXPECTED THIS AFTERNOON WILL ENCOURAGE
INCREASINGLY GUSTY WEST WINDS THIS AFTERNOON. GIVEN THE STEEP
LAPSE RATES AND ANOTHER WEAK DISTURBANCE UPSTREAM CANNOT
COMPLETELY RULE OUT ANOTHER BRIEF SNOW SHOWER LATE THIS AFTERNOON
INTO EARLY THIS EVENING...THOUGH CHANCES LOOK LOW ENOUGH TO KEEP
IT OUT OF THE TAF. COULD ALSO BE SOME PERIODIC MVFR CIGS THIS
AFTERNOON INTO THE EVENING...THOUGH PROBABLY MORE PREVAILING VFR.
WINDS GRADUALLY DIMINISH TONIGHT AND THEN BEGIN TO BACK TO
SOUTHERLY WEDNESDAY MORNING. SOUTH WINDS WILL INCREASE AND ATTAIN
SOME GUSTINESS UP TO 20-25KT WEDNESDAY AFTERNOON.
IZZI
//ORD AND MDW CONFIDENCE...UPDATED 18Z...
* LOW CONFIDENCE IN A BRIEF SNOW SHOWER LATE THIS
AFTERNOON/EVENING
* LOW-MEDIUM CONFIDENCE IN CIGS REMAINING VFR
* HIGH CONFIDENCE IN REMAINING FORECAST ELEMENTS
IZZI
//OUTLOOK FOR ORD/MDW FOR 00Z THURSDAY-12Z TUESDAY...UPDATED 18Z...
WEDNESDAY NIGHT...IFR/LIFR CIGS PROBABLY DEVELOPING.
THURSDAY...IFR/LIFR LIKELY. CHANCE OF -RA/DZ.
FRIDAY...IFR LIKELY. CHANCE OF -RA/-SN.
SATURDAY...IFR POSSIBLE. CHANCE OF SNOW...MAINLY AT NIGHT.
SUNDAY...IFR POSSIBLE. CHANCE OF SNOW.
MONDAY...MVFR CIGS POSSIBLE.
IZZI
&&
.MARINE...
306 AM CST
FIRST OF ALL MADE NO CHANGES TO THE ONGOING HEADLINES AS THEY ALL
SEEM ON TRACK. A SMALL CRAFT ADVISORY WILL BE NEEDED FOR THE INDIANA
NEARSHORE WATERS AFTER THE GALE WARNING DUE TO LINGERING HAZARDOUS
WAVES.
LOW PRESSURE IS OVER ONTARIO AND IT WILL SLIDE TO THE EAST
TODAY...WHILE ITS COLD FRONT PASSES OVER THE LAKE THIS AFTERNOON.
AT THE SAME TIME HIGH PRESSURE BUILDS OVER THE CENTRAL PLAINS. THIS
WILL TIGHTEN THE PRESSURE GRADIENT OVER THE SOUTHERN END OF THE
LAKE...RESULTING IN LOW END GALES FORMING THIS MORNING THROUGH EARLY
THIS EVENING. WEST WINDS DIMINISH TO ARND 20 KT BY WEDNESDAY
MORNING AS HIGH PRESSURE PASSES TO THE SOUTH. WINDS PICK BACK UP ON
THE BACKSIDE OF THE HIGH LATE WEDNESDAY AFTERNOON INTO WEDNESDAY
EVENING. A BRIEF PERIOD OF SW GALES TO 35 KT IS POSSIBLE DURING
THAT TIME. A SMALL CRAFT ADVISORY WILL LIKELY BE NEEDED AS WELL FOR
WEDNESDAY AFTERNOON AND EVENING. WINDS WEAKEN WEDNESDAY NIGHT AS A
TROUGH OF LOW PRESSURE SITS OVER THE LAKE WEDNESDAY NIGHT THROUGH
THURSDAY. THE NEXT WEAK LOW MOVES OVER THE LAKE THURSDAY NIGHT
BEFORE SHIFTING EAST ON FRIDAY. WINDS TURN LIGHT AND VARIABLE
BEHIND THE LOW ON SATURDAY...BUT THEN TURN NORTH AND STRENGTHEN
SATURDAY NIGHT INTO SUNDAY IN RESPONSE TO THE NEXT SYSTEM. GUIDANCE
FEATURES ANOTHER LOW PUSHING UP THE OHIO RIVER VALLEY SATURDAY NIGHT
INTO SUNDAY WITH HIGH PRESSURE BUILDING DOWN THE PLAINS.
JEE
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...GALE WARNING...LMZ080-LMZ567-LMZ669-LMZ671-LMZ673-LMZ675-LMZ744-
LMZ745-LMZ777-LMZ779-LMZ868-LMZ870-LMZ872-LMZ874-LMZ876-
LMZ878 UNTIL 9 PM TUESDAY.
SMALL CRAFT ADVISORY...NEARSHORE WINTHROP HARBOR TO GARY IN UNTIL
MIDNIGHT WEDNESDAY.
&&
$$
VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)
FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/US.NATIONALWEATHERSERVICE.CHICAGO.GOV
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
1022 AM CST TUE DEC 17 2013
.DISCUSSION...
328 AM CST
TODAY...
MAIN CONCERNS WILL BE FOCUSED ON THE MID-LVL WAVE THAT IS QUICKLY
SLIDING EAST ACROSS THE WESTERN GREAT LAKES...POSSIBLY BRINGING A
SLUG OF LGT SNOW TO NORTH/NORTHEAST IL AND NORTHWEST IN THIS MORNING
THRU MIDDAY. THEN THE POTENTIAL FOR SOME BLOWING SNOW AS THE
GRADIENT RAMPS UP MIDDAY AND MIXING JUMPS TO ARND 3KFT AGL.
IR IMAGERY SHOWS CONSIDERABLE CLOUD COVER ACROSS THE REGION...AND
SOME COOLING WITH CLOUD TOPS WITH THE WEAK WAVE SLIDING EAST ACROSS
WESTCENTRAL WISC EARLY THIS MORNING. KARX RADAR INDICATES AN AREA OF
RETURNS ACROSS THIS AREA...HOWEVER THE RECENT COUPLE OF HOURS HAVE
INDICATED SOME DOWNWARD TREND IN THE SOUTHERN PORTION OF THIS
PRECIP. SFC OBS ARE NOT INDICATING ANY SNOW IN FAR SOUTHEAST MN AND
HAS TENDED TO BE FOCUSED FURTHER NORTH. BASED ON CURRENT
TRAJECTORY...THE BEST LGT SNOW MAY END UP HOLDING FURTHER NORTH INTO
WISC. BUFR PROFILES HAVE BACKED OFF ON THE OMEGA PLACEMENT...HOWEVER
A HANDFUL OF POINTS CONTINUE TO INDICATE SOME DEGREE OF LIFT THROUGH
THE FAVORED DGZ ARND 12-15Z. DPROG/DT OF THE BUFR SITES ALSO
INDICATES A DOWNWARD TREND...SUPPORTING THE LOWER CONFIDENCE IN SNOW
TOTALS. THE CAVEAT AND CHALLENGE IS THE NARROW CHANNEL OF MOISTURE
THAT STRETCHES WEST AND RECENT RAP GUIDANCE HAS INDICATED AN
ENHANCEMENT TO THIS FEATURE AS IT PIVOTS EAST ACROSS THE CWFA THIS
MORNING.
SNOWFALL RATIOS SHOULD FALL AROUND 20:1...SO RATHER DRY.
BASED ON COBB OUTPUT FROM THESE PROFILES SNOWFALL SHUD GENERALLY
FALL BETWEEN A FEW TENTHS TO 1". COULD SEE AREAS CLOSEST TO THE
WISCONSIN STATELINE PICKING UP SLIGHTLY MORE OR WITHIN A 1-2" RANGE.
THE WAVE WILL REMAIN PROGRESSIVE AND SHUD COME TO AN END BY 15-17Z
FROM WEST TO EAST...AS WIND GUSTS BEGIN TO DEVELOP. ANY FRESH
SNOWFALL SHUD EASILY BLOW AROUND. THIS MAY BE MORE FOCUSED ACROSS
AREAS NORTH OF I-80...AS THE PATCHY DZ EARLY THIS MORNING WILL
MOISTEN UP THE SNOW FURTHER SOUTH AND LIMIT THE ABILITY FOR THE SNOW
TO BLOW AROUND.
TEMPS WILL BEGIN TO REBOUND TDY...AS THE 500MB TROUGH AXIS BEGINS TO
PUSH EAST OF THE WESTERN GREAT LAKES. TEMPS WILL STEADILY WARM INTO
THE UPR 20S TO ARND 30 ACROSS THE SOUTHERN CWFA.
CONFIDENCE IN SNOWFALL...MEDIUM/LOW.
CONFIDENCE IN TEMPS...HIGH.
TONIGHT THROUGH WEDNESDAY...
500MB HEIGHTS BEGIN TO RISE THIS EVENING WITH DIFFLUENT FLOW LIFTING
NORTH FROM THE SFC RIDGE CENTERED ACROSS THE OZARKS. THIS SHUD AID
IN ERODING SOME OF THE CLOUD COVER...AND COULD SEE P-CLOUDY SKIES
FOR A BRIEF PERIOD OVERNIGHT. THEN ANOTHER WEAK MID-LVL WAVE IS
PROGGED TO BUMP INTO THE DIFFLUENT FLOW AND BRING SOME MID-LVL
MOISTURE AND CLOUDS BACK TO THE AREA DURING THE OVERNIGHT HOURS.
500MB FLOW CONTINUES TO EVOLVE INTO A ZONAL SETUP...ALTHOUGH THIS
WILL ONLY BE TEMPORARY THRU WED. SFC RIDGE ACROSS THE OZARKS DRIFTS
EAST TOWARDS THE MID-ATLANTIC/GULF STATES...WITH LLVL FLOW TURNING
SOUTH/SOUTHWEST FOR THE CWFA.
FOR THE FIRST TIME IN SEVERAL DAYS WED MAY SEE THE 850MB 0 DEG
ISOTHERM LIFT OVERHEAD ALONG THE LEADING EDGE OF INCREASED WARM AIR
ADVECTION. THE MID-LVL THERMAL RIDGE CONTINUES TO WARM FURTHER SOUTH
WITH TEMPS RISING TO NEAR 9 DEG C OVER NORTHERN MISSOURI WED AFTN.
GIVEN THE EXPANSIVE SNOW COVER...THE CHALLENGE IS HOW WARM WILL WED
END UP BECOMING. GUIDANCE HAS TRENDED SLIGHTLY COOLER OVER THE PAST
FEW DAYS WITH WED HIGHS. AT THIS TIME THE GENERAL CONSENSUS HAS BEEN
ON TEMPS IN THE LOW 30S ALONG/NORTH OF I-80 AND POINTS SOUTH
POSSIBLY REACHING THE MID 30S.
WITH DEW POINTS PROGGED TO BE RISING TO ARND FREEZING...THE SNOWMELT
RATES WILL RAMP UP. WITH THE ADDED MOISTURE COUPLED WITH A
MOISTENING MID/UPR LVLS AHEAD OF THE NEXT WEATHER SYSTEM...THE
ENVIRONMENT SEEMS PRIMED FOR THE DEVELOPMENT OF PATCHY/AREAS OF FOG.
FREQUENTLY MELTING SNOW CAN PRODUCE SHALLOW DENSE FOG...SO THIS WILL
CONTINUE TO BE THE FOCUS WED NGT.
CONFIDENCE IN TEMPS...MEDIUM.
CONFIDENCE IN FOG DEVELOPING WED NGT...HIGH.
THURSDAY THROUGH SATURDAY...
MID-LVL FLOW CONTINUES TO PROGRESS INTO A SOUTHWEST SETUP WITH A
500MB VORT MAX PUSHING INTO THE FOUR-CORNERS REGION THUR. SFC
RIDGING IN THE LLVLS WILL BE PARKED OVER THE SOUTHEASTERN
CONUS...ALLOWING FOR CONTINUED FEED OF WARM AIR ADVECTING NORTH
THROUGH THE OZARKS INTO THE OHIO VALLEY/GREAT LAKES REGIONS THUR.
GUIDANCE CONTINUES TO FEATURE A WAVE DEVELOPING ALONG THE LEE-SIDE
OF THE ROCKIES THUR...AS A WEAK SFC RIDGE SAGS SOUTH FROM CENTRAL
CANADA INTO THE UPPER MIDWEST AND SHARPENS UP A BAROCLINIC ZONE OVER
THE NORTHERN PLAINS STRETCHING NORTHEAST THROUGH THE UPPER PENINSULA
OF MICHIGNA. THIS WILL LIKELY KEEP THE WARM AIR OVER THE CWFA
THUR...AND ANY PRECIP WILL LIKELY FALL AS LIQUID THUR. AT THE ONSET
THUR MORNING A BRIEF PERIOD OF FZDZ/FZRA MAY OCCUR...HOWEVER THIS
WILL LIKELY BE BRIEF. GUIDANCE HAS TRENDED SLIGHTLY FURTHER SOUTH
WITH THE SFC LOW FOR THUR NIGHT...AS THE 850MB LOW IS PROGGED TO
SLIDE OVER SOUTHCENTRAL WISC.
WITH SOME DEGREE OF UNCERTAINTY REMAINING IN THE PLACEMENT OF THE
SFC LOW...THIS OPENS UP DECREASED CONFIDENCE IN HIGH TEMPS FOR THUR.
A FURTHER NORTH PATH WOULD PROVIDE TEMPS IN THE MID/UPR
30S...MEANWHILE A CORRECTION TO THE SOUTH WOULD KEEP TEMPS ARND 30
TO LOW 30S. FURTHER COMPOUNDING THIS WOULD BE THE THEN POTENTIAL FOR
P-TYPE ISSUES.
THE SFC RIDGE ACROSS THE UPPER MIDWEST SHUD HELP TO PUSH THE
BAROCLINIC BOUNDARY SOUTH FOR FRI...AS THE LOW LIFTS NORTHEAST OF
THE FORECAST AREA. THIS SHUD AID IN COOLER AIR FILTERING IN BEHIND
AND PUSHING DEW POINTS BACK INTO THE 20S. P-TYPE FOR FRI SHUD BE
LIMITED TO RA/SN...AND TRANSITION TO ALL SN BY FRI AFTN/EVE.
500MB VORT MAX ACROSS THE FAR SOUTHWEST CONUS WILL BEGIN TO DIG
SOUTHEAST OF NEW MEXICO...WHICH WILL LIKELY TRANSLATE IN THE
DOWNSTREAM BOUNDARY SAGGING FURTHER SOUTH THROUGH THE OHIO VALLEY
FRI NGT. THEN YET ANOTHER WAVE IS PROGGED TO DEVELOP ACROSS EASTERN
TEXAS AND TAKE A CLASSIC TRAJECTORY TOWARDS THE OHIO VALLEY FOR THE
SECOND HALF OF THE WEEKEND.
CONFIDENCE IN TEMPS...MEDIUM/HIGH.
SUNDAY THROUGH EARLY CHRISTMAS WEEK...
ENSEMBLES INDICATE A SIMILAR COLD SETUP FOR THE SECOND HALF OF THE
WEEKEND INTO EARLY CHRISTMAS WEEK. WESTERN MID-LVL RIDGE MAY BEGIN
TO AMPLIFY FOR EARLY NEXT WEEK...RESULTING IN A DOWNSTREAM TROUGH
POSITIONED OVER THE GREAT LAKES REGION. OPERATIONAL SOLUTIONS
CONTINUE TO POINT TOWARDS A ROBUST WEATHER SYSTEM SUN LIFTING
NORTHEAST ACROSS THE REGION FROM THE SOUTHERN PLAINS/EASTERN
TEXAS...WITH TEMPS COLD ENOUGH TO SUPPORT ALL SNOW FOR THIS EVENT.
THEN ON THE BACKSIDE OF THIS MUCH COLDER AIR POURS BACK INTO THE
CWFA WITH TEMPS ALOFT RETURNING TO -10 TO -14 DEG C AT 850MB FOR
EARLY CHRISTMAS WEEK. THIS WILL KEEP SFC TEMPS IN THE UPPER TEENS TO
LOW 20S.
CONFIDENCE IN SUNDAY SYSTEM...HIGH.
CONFIDENCE IN TEMPS...MEDIUM/HIGH.
BEACHLER
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 16Z...
* TRENDING VFR THIS AFTERNOON
* GUSTY WEST WINDS THIS AFTERNOON
IZZI
//DISCUSSION...UPDATED 14Z
RADAR TRENDS SHOW SNOW SHOWERS DRYING UP OVER THE AREA AND HAVE
CONSIDERABLY BACKED OFF ON SNOW MENTION IN THE TAFS. VSBY ALREADY
JUST BARELY ABOVE IFR...SO WOULDNT TAKE MUCH SNOW TO DROP VSBY TO
IFR BUT ACCUMS SHOULD JUST BE A DUSTING AT WORST. NORTH-SOUTH EDGE
TO IFR CIGS MAKING STEADY PROGRESS EAST AND SHOULD CLEAR OUT OF
ORD/MDW BY 17Z.
IZZI
UPDATED 12Z...
IFR CIGS HAVE SPREAD ACROSS THE TERMINALS AS THE LOW PRESSURE
TROUGH APPROACHES FROM THE WEST. THE MAIN LOW WILL PASS TO OUR
NORTH THROUGH ONTARIO TODAY...WITH ITS COLD FRONT SWINGING THROUGH
THIS AFTN. A BAND OF SNOW HAS FORMED OVER SOUTHERN WI AND
EXPECTING IT TO REACH RFD ARND 1230Z...THEN AT ORD BY 13Z. UNTIL
THEN...EXPECTING CONDITIONS TO STAY RIGHT WHERE THEY ARE. IFR
CIGS AND VFR/MVFR VSBY. WHEN THE SNOW ARRIVES...VSBYS WILL FALL
FURTHER TO AROUND A MILE. THERE SHOULD BE A BRIEF PERIOD OF
HEAVIER SNOW WITH VSBYS BELOW 1 MILE.
WINDS PICK UP AFTER THE COLD FRONT WITH GUSTS AROUND 30 KT. KEPT
MVFR CIGS GOING...BUT GUIDANCE SUGGESTS MVFR OR LOWER CIGS COULD
HANG AROUND LONGER THAN CURRENTLY FORECAST. BLOWING SNOW WILL
LIKELY BE AN ISSUE GIVEN THE FRESH LIGHT SNOW. NOT EXPECTING IT TO
IMPACT VSBY THOUGH.
HIGH PRESSURE PASSES TO THE SOUTH OVERNIGHT WITH WINDS BECOMING
SOUTHWEST AROUND 10 KT. WINDS TURN FURTHER SOUTH AND BEGIN GUSTING
TO AROUND 20 KT IN THE LATE MORNING...BUT EXPECTING VFR CONDITIONS.
JEE
//ORD AND MDW CONFIDENCE...UPDATED 14Z...
* MEDIUM CONFIDENCE ON VFR CIGS THIS AFTERNOON
* HIGH CONFIDENCE IN REST OF FORECAST
IZZI
//OUTLOOK FOR ORD/MDW FOR 00Z THURSDAY-12Z TUESDAY...UPDATED 12Z...
WEDNESDAY NIGHT...IFR/LIFR CIGS PROBABLY DEVELOPING.
THURSDAY...IFR/LIFR LIKELY. CHANCE OF -RA/DZ.
FRIDAY...IFR LIKELY. CHANCE OF -RA/-SN.
SATURDAY...IFR POSSIBLE. CHANCE OF SNOW...MAINLY AT NIGHT.
SUNDAY...IFR POSSIBLE. CHANCE OF SNOW.
MONDAY...MVFR CIGS POSSIBLE.
IZZI
&&
.MARINE...
306 AM CST
FIRST OF ALL MADE NO CHANGES TO THE ONGOING HEADLINES AS THEY ALL
SEEM ON TRACK. A SMALL CRAFT ADVISORY WILL BE NEEDED FOR THE INDIANA
NEARSHORE WATERS AFTER THE GALE WARNING DUE TO LINGERING HAZARDOUS
WAVES.
LOW PRESSURE IS OVER ONTARIO AND IT WILL SLIDE TO THE EAST
TODAY...WHILE ITS COLD FRONT PASSES OVER THE LAKE THIS AFTERNOON.
AT THE SAME TIME HIGH PRESSURE BUILDS OVER THE CENTRAL PLAINS. THIS
WILL TIGHTEN THE PRESSURE GRADIENT OVER THE SOUTHERN END OF THE
LAKE...RESULTING IN LOW END GALES FORMING THIS MORNING THROUGH EARLY
THIS EVENING. WEST WINDS DIMINISH TO ARND 20 KT BY WEDNESDAY
MORNING AS HIGH PRESSURE PASSES TO THE SOUTH. WINDS PICK BACK UP ON
THE BACKSIDE OF THE HIGH LATE WEDNESDAY AFTERNOON INTO WEDNESDAY
EVENING. A BRIEF PERIOD OF SW GALES TO 35 KT IS POSSIBLE DURING
THAT TIME. A SMALL CRAFT ADVISORY WILL LIKELY BE NEEDED AS WELL FOR
WEDNESDAY AFTERNOON AND EVENING. WINDS WEAKEN WEDNESDAY NIGHT AS A
TROUGH OF LOW PRESSURE SITS OVER THE LAKE WEDNESDAY NIGHT THROUGH
THURSDAY. THE NEXT WEAK LOW MOVES OVER THE LAKE THURSDAY NIGHT
BEFORE SHIFTING EAST ON FRIDAY. WINDS TURN LIGHT AND VARIABLE
BEHIND THE LOW ON SATURDAY...BUT THEN TURN NORTH AND STRENGTHEN
SATURDAY NIGHT INTO SUNDAY IN RESPONSE TO THE NEXT SYSTEM. GUIDANCE
FEATURES ANOTHER LOW PUSHING UP THE OHIO RIVER VALLEY SATURDAY NIGHT
INTO SUNDAY WITH HIGH PRESSURE BUILDING DOWN THE PLAINS.
JEE
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...GALE WARNING...LMZ080-LMZ567-LMZ669-LMZ671-LMZ673-LMZ675-LMZ744-
LMZ745-LMZ777-LMZ779-LMZ868-LMZ870-LMZ872-LMZ874-LMZ876-
LMZ878 UNTIL 9 PM TUESDAY.
SMALL CRAFT ADVISORY...NEARSHORE WINTHROP HARBOR TO GARY IN UNTIL
MIDNIGHT WEDNESDAY.
&&
$$
VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)
FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/US.NATIONALWEATHERSERVICE.CHICAGO.GOV
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
840 AM CST TUE DEC 17 2013
.DISCUSSION...
328 AM CST
TODAY...
MAIN CONCERNS WILL BE FOCUSED ON THE MID-LVL WAVE THAT IS QUICKLY
SLIDING EAST ACROSS THE WESTERN GREAT LAKES...POSSIBLY BRINGING A
SLUG OF LGT SNOW TO NORTH/NORTHEAST IL AND NORTHWEST IN THIS MORNING
THRU MIDDAY. THEN THE POTENTIAL FOR SOME BLOWING SNOW AS THE
GRADIENT RAMPS UP MIDDAY AND MIXING JUMPS TO ARND 3KFT AGL.
IR IMAGERY SHOWS CONSIDERABLE CLOUD COVER ACROSS THE REGION...AND
SOME COOLING WITH CLOUD TOPS WITH THE WEAK WAVE SLIDING EAST ACROSS
WESTCENTRAL WISC EARLY THIS MORNING. KARX RADAR INDICATES AN AREA OF
RETURNS ACROSS THIS AREA...HOWEVER THE RECENT COUPLE OF HOURS HAVE
INDICATED SOME DOWNWARD TREND IN THE SOUTHERN PORTION OF THIS
PRECIP. SFC OBS ARE NOT INDICATING ANY SNOW IN FAR SOUTHEAST MN AND
HAS TENDED TO BE FOCUSED FURTHER NORTH. BASED ON CURRENT
TRAJECTORY...THE BEST LGT SNOW MAY END UP HOLDING FURTHER NORTH INTO
WISC. BUFR PROFILES HAVE BACKED OFF ON THE OMEGA PLACEMENT...HOWEVER
A HANDFUL OF POINTS CONTINUE TO INDICATE SOME DEGREE OF LIFT THROUGH
THE FAVORED DGZ ARND 12-15Z. DPROG/DT OF THE BUFR SITES ALSO
INDICATES A DOWNWARD TREND...SUPPORTING THE LOWER CONFIDENCE IN SNOW
TOTALS. THE CAVEAT AND CHALLENGE IS THE NARROW CHANNEL OF MOISTURE
THAT STRETCHES WEST AND RECENT RAP GUIDANCE HAS INDICATED AN
ENHANCEMENT TO THIS FEATURE AS IT PIVOTS EAST ACROSS THE CWFA THIS
MORNING.
SNOWFALL RATIOS SHOULD FALL AROUND 20:1...SO RATHER DRY.
BASED ON COBB OUTPUT FROM THESE PROFILES SNOWFALL SHUD GENERALLY
FALL BETWEEN A FEW TENTHS TO 1". COULD SEE AREAS CLOSEST TO THE
WISCONSIN STATELINE PICKING UP SLIGHTLY MORE OR WITHIN A 1-2" RANGE.
THE WAVE WILL REMAIN PROGRESSIVE AND SHUD COME TO AN END BY 15-17Z
FROM WEST TO EAST...AS WIND GUSTS BEGIN TO DEVELOP. ANY FRESH
SNOWFALL SHUD EASILY BLOW AROUND. THIS MAY BE MORE FOCUSED ACROSS
AREAS NORTH OF I-80...AS THE PATCHY DZ EARLY THIS MORNING WILL
MOISTEN UP THE SNOW FURTHER SOUTH AND LIMIT THE ABILITY FOR THE SNOW
TO BLOW AROUND.
TEMPS WILL BEGIN TO REBOUND TDY...AS THE 500MB TROUGH AXIS BEGINS TO
PUSH EAST OF THE WESTERN GREAT LAKES. TEMPS WILL STEADILY WARM INTO
THE UPR 20S TO ARND 30 ACROSS THE SOUTHERN CWFA.
CONFIDENCE IN SNOWFALL...MEDIUM/LOW.
CONFIDENCE IN TEMPS...HIGH.
TONIGHT THROUGH WEDNESDAY...
500MB HEIGHTS BEGIN TO RISE THIS EVENING WITH DIFFLUENT FLOW LIFTING
NORTH FROM THE SFC RIDGE CENTERED ACROSS THE OZARKS. THIS SHUD AID
IN ERODING SOME OF THE CLOUD COVER...AND COULD SEE P-CLOUDY SKIES
FOR A BRIEF PERIOD OVERNIGHT. THEN ANOTHER WEAK MID-LVL WAVE IS
PROGGED TO BUMP INTO THE DIFFLUENT FLOW AND BRING SOME MID-LVL
MOISTURE AND CLOUDS BACK TO THE AREA DURING THE OVERNIGHT HOURS.
500MB FLOW CONTINUES TO EVOLVE INTO A ZONAL SETUP...ALTHOUGH THIS
WILL ONLY BE TEMPORARY THRU WED. SFC RIDGE ACROSS THE OZARKS DRIFTS
EAST TOWARDS THE MID-ATLANTIC/GULF STATES...WITH LLVL FLOW TURNING
SOUTH/SOUTHWEST FOR THE CWFA.
FOR THE FIRST TIME IN SEVERAL DAYS WED MAY SEE THE 850MB 0 DEG
ISOTHERM LIFT OVERHEAD ALONG THE LEADING EDGE OF INCREASED WARM AIR
ADVECTION. THE MID-LVL THERMAL RIDGE CONTINUES TO WARM FURTHER SOUTH
WITH TEMPS RISING TO NEAR 9 DEG C OVER NORTHERN MISSOURI WED AFTN.
GIVEN THE EXPANSIVE SNOW COVER...THE CHALLENGE IS HOW WARM WILL WED
END UP BECOMING. GUIDANCE HAS TRENDED SLIGHTLY COOLER OVER THE PAST
FEW DAYS WITH WED HIGHS. AT THIS TIME THE GENERAL CONSENSUS HAS BEEN
ON TEMPS IN THE LOW 30S ALONG/NORTH OF I-80 AND POINTS SOUTH
POSSIBLY REACHING THE MID 30S.
WITH DEW POINTS PROGGED TO BE RISING TO ARND FREEZING...THE SNOWMELT
RATES WILL RAMP UP. WITH THE ADDED MOISTURE COUPLED WITH A
MOISTENING MID/UPR LVLS AHEAD OF THE NEXT WEATHER SYSTEM...THE
ENVIRONMENT SEEMS PRIMED FOR THE DEVELOPMENT OF PATCHY/AREAS OF FOG.
FREQUENTLY MELTING SNOW CAN PRODUCE SHALLOW DENSE FOG...SO THIS WILL
CONTINUE TO BE THE FOCUS WED NGT.
CONFIDENCE IN TEMPS...MEDIUM.
CONFIDENCE IN FOG DEVELOPING WED NGT...HIGH.
THURSDAY THROUGH SATURDAY...
MID-LVL FLOW CONTINUES TO PROGRESS INTO A SOUTHWEST SETUP WITH A
500MB VORT MAX PUSHING INTO THE FOUR-CORNERS REGION THUR. SFC
RIDGING IN THE LLVLS WILL BE PARKED OVER THE SOUTHEASTERN
CONUS...ALLOWING FOR CONTINUED FEED OF WARM AIR ADVECTING NORTH
THROUGH THE OZARKS INTO THE OHIO VALLEY/GREAT LAKES REGIONS THUR.
GUIDANCE CONTINUES TO FEATURE A WAVE DEVELOPING ALONG THE LEE-SIDE
OF THE ROCKIES THUR...AS A WEAK SFC RIDGE SAGS SOUTH FROM CENTRAL
CANADA INTO THE UPPER MIDWEST AND SHARPENS UP A BAROCLINIC ZONE OVER
THE NORTHERN PLAINS STRETCHING NORTHEAST THROUGH THE UPPER PENINSULA
OF MICHIGNA. THIS WILL LIKELY KEEP THE WARM AIR OVER THE CWFA
THUR...AND ANY PRECIP WILL LIKELY FALL AS LIQUID THUR. AT THE ONSET
THUR MORNING A BRIEF PERIOD OF FZDZ/FZRA MAY OCCUR...HOWEVER THIS
WILL LIKELY BE BRIEF. GUIDANCE HAS TRENDED SLIGHTLY FURTHER SOUTH
WITH THE SFC LOW FOR THUR NIGHT...AS THE 850MB LOW IS PROGGED TO
SLIDE OVER SOUTHCENTRAL WISC.
WITH SOME DEGREE OF UNCERTAINTY REMAINING IN THE PLACEMENT OF THE
SFC LOW...THIS OPENS UP DECREASED CONFIDENCE IN HIGH TEMPS FOR THUR.
A FURTHER NORTH PATH WOULD PROVIDE TEMPS IN THE MID/UPR
30S...MEANWHILE A CORRECTION TO THE SOUTH WOULD KEEP TEMPS ARND 30
TO LOW 30S. FURTHER COMPOUNDING THIS WOULD BE THE THEN POTENTIAL FOR
P-TYPE ISSUES.
THE SFC RIDGE ACROSS THE UPPER MIDWEST SHUD HELP TO PUSH THE
BAROCLINIC BOUNDARY SOUTH FOR FRI...AS THE LOW LIFTS NORTHEAST OF
THE FORECAST AREA. THIS SHUD AID IN COOLER AIR FILTERING IN BEHIND
AND PUSHING DEW POINTS BACK INTO THE 20S. P-TYPE FOR FRI SHUD BE
LIMITED TO RA/SN...AND TRANSITION TO ALL SN BY FRI AFTN/EVE.
500MB VORT MAX ACROSS THE FAR SOUTHWEST CONUS WILL BEGIN TO DIG
SOUTHEAST OF NEW MEXICO...WHICH WILL LIKELY TRANSLATE IN THE
DOWNSTREAM BOUNDARY SAGGING FURTHER SOUTH THROUGH THE OHIO VALLEY
FRI NGT. THEN YET ANOTHER WAVE IS PROGGED TO DEVELOP ACROSS EASTERN
TEXAS AND TAKE A CLASSIC TRAJECTORY TOWARDS THE OHIO VALLEY FOR THE
SECOND HALF OF THE WEEKEND.
CONFIDENCE IN TEMPS...MEDIUM/HIGH.
SUNDAY THROUGH EARLY CHRISTMAS WEEK...
ENSEMBLES INDICATE A SIMILAR COLD SETUP FOR THE SECOND HALF OF THE
WEEKEND INTO EARLY CHRISTMAS WEEK. WESTERN MID-LVL RIDGE MAY BEGIN
TO AMPLIFY FOR EARLY NEXT WEEK...RESULTING IN A DOWNSTREAM TROUGH
POSITIONED OVER THE GREAT LAKES REGION. OPERATIONAL SOLUTIONS
CONTINUE TO POINT TOWARDS A ROBUST WEATHER SYSTEM SUN LIFTING
NORTHEAST ACROSS THE REGION FROM THE SOUTHERN PLAINS/EASTERN
TEXAS...WITH TEMPS COLD ENOUGH TO SUPPORT ALL SNOW FOR THIS EVENT.
THEN ON THE BACKSIDE OF THIS MUCH COLDER AIR POURS BACK INTO THE
CWFA WITH TEMPS ALOFT RETURNING TO -10 TO -14 DEG C AT 850MB FOR
EARLY CHRISTMAS WEEK. THIS WILL KEEP SFC TEMPS IN THE UPPER TEENS TO
LOW 20S.
CONFIDENCE IN SUNDAY SYSTEM...HIGH.
CONFIDENCE IN TEMPS...MEDIUM/HIGH.
BEACHLER
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 14Z...
* ISOLD SHSN THROUGH 16Z
* IFR CIGS CLEAR OUT LATER THIS MORNING
* GUSTY WEST WINDS DEVELOP LATER THIS MORNING AND CONTINUE INTO
THE AFTERNOON
IZZI
//DISCUSSION...UPDATED 14Z
RADAR TRENDS SHOW SNOW SHOWERS DRYING UP OVER THE AREA AND HAVE
CONSIDERABLY BACKED OFF ON SNOW MENTION IN THE TAFS. VSBY ALREADY
JUST BARELY ABOVE IFR...SO WOULDNT TAKE MUCH SNOW TO DROP VSBY TO
IFR BUT ACCUMS SHOULD JUST BE A DUSTING AT WORST. NORTH-SOUTH EDGE
TO IFR CIGS MAKING STEADY PROGRESS EAST AND SHOULD CLEAR OUT OF
ORD/MDW BY 17Z.
IZZI
UPDATED 12Z...
IFR CIGS HAVE SPREAD ACROSS THE TERMINALS AS THE LOW PRESSURE
TROUGH APPROACHES FROM THE WEST. THE MAIN LOW WILL PASS TO OUR
NORTH THROUGH ONTARIO TODAY...WITH ITS COLD FRONT SWINGING THROUGH
THIS AFTN. A BAND OF SNOW HAS FORMED OVER SOUTHERN WI AND
EXPECTING IT TO REACH RFD ARND 1230Z...THEN AT ORD BY 13Z. UNTIL
THEN...EXPECTING CONDITIONS TO STAY RIGHT WHERE THEY ARE. IFR
CIGS AND VFR/MVFR VSBY. WHEN THE SNOW ARRIVES...VSBYS WILL FALL
FURTHER TO AROUND A MILE. THERE SHOULD BE A BRIEF PERIOD OF
HEAVIER SNOW WITH VSBYS BELOW 1 MILE.
WINDS PICK UP AFTER THE COLD FRONT WITH GUSTS AROUND 30 KT. KEPT
MVFR CIGS GOING...BUT GUIDANCE SUGGESTS MVFR OR LOWER CIGS COULD
HANG AROUND LONGER THAN CURRENTLY FORECAST. BLOWING SNOW WILL
LIKELY BE AN ISSUE GIVEN THE FRESH LIGHT SNOW. NOT EXPECTING IT TO
IMPACT VSBY THOUGH.
HIGH PRESSURE PASSES TO THE SOUTH OVERNIGHT WITH WINDS BECOMING
SOUTHWEST AROUND 10 KT. WINDS TURN FURTHER SOUTH AND BEGIN GUSTING
TO AROUND 20 KT IN THE LATE MORNING...BUT EXPECTING VFR CONDITIONS.
JEE
//ORD AND MDW CONFIDENCE...UPDATED 14Z...
* MEDIUM TO HIGH CONFIDENCE IN SNOW THIS MORNING
* MEDIUM CONFIDENCE ON EXACT TIMING OF IFR CIGS MOVING OUT THIS MORNING
* MEDIUM CONFIDENCE ON VFR CIGS THIS AFTERNOON
* HIGH CONFIDENCE IN REST OF FORECAST
IZZI
//OUTLOOK FOR ORD/MDW FOR 00Z THURSDAY-12Z TUESDAY...UPDATED 12Z...
WEDNESDAY NIGHT...IFR/LIFR CIGS PROBABLY DEVELOPING.
THURSDAY...IFR/LIFR LIKELY. CHANCE OF -RA/DZ.
FRIDAY...IFR LIKELY. CHANCE OF -RA/-SN.
SATURDAY...IFR POSSIBLE. CHANCE OF SNOW...MAINLY AT NIGHT.
SUNDAY...IFR POSSIBLE. CHANCE OF SNOW.
MONDAY...MVFR CIGS POSSIBLE.
IZZI
&&
.MARINE...
306 AM CST
FIRST OF ALL MADE NO CHANGES TO THE ONGOING HEADLINES AS THEY ALL
SEEM ON TRACK. A SMALL CRAFT ADVISORY WILL BE NEEDED FOR THE INDIANA
NEARSHORE WATERS AFTER THE GALE WARNING DUE TO LINGERING HAZARDOUS
WAVES.
LOW PRESSURE IS OVER ONTARIO AND IT WILL SLIDE TO THE EAST
TODAY...WHILE ITS COLD FRONT PASSES OVER THE LAKE THIS AFTERNOON.
AT THE SAME TIME HIGH PRESSURE BUILDS OVER THE CENTRAL PLAINS. THIS
WILL TIGHTEN THE PRESSURE GRADIENT OVER THE SOUTHERN END OF THE
LAKE...RESULTING IN LOW END GALES FORMING THIS MORNING THROUGH EARLY
THIS EVENING. WEST WINDS DIMINISH TO ARND 20 KT BY WEDNESDAY
MORNING AS HIGH PRESSURE PASSES TO THE SOUTH. WINDS PICK BACK UP ON
THE BACKSIDE OF THE HIGH LATE WEDNESDAY AFTERNOON INTO WEDNESDAY
EVENING. A BRIEF PERIOD OF SW GALES TO 35 KT IS POSSIBLE DURING
THAT TIME. A SMALL CRAFT ADVISORY WILL LIKELY BE NEEDED AS WELL FOR
WEDNESDAY AFTERNOON AND EVENING. WINDS WEAKEN WEDNESDAY NIGHT AS A
TROUGH OF LOW PRESSURE SITS OVER THE LAKE WEDNESDAY NIGHT THROUGH
THURSDAY. THE NEXT WEAK LOW MOVES OVER THE LAKE THURSDAY NIGHT
BEFORE SHIFTING EAST ON FRIDAY. WINDS TURN LIGHT AND VARIABLE
BEHIND THE LOW ON SATURDAY...BUT THEN TURN NORTH AND STRENGTHEN
SATURDAY NIGHT INTO SUNDAY IN RESPONSE TO THE NEXT SYSTEM. GUIDANCE
FEATURES ANOTHER LOW PUSHING UP THE OHIO RIVER VALLEY SATURDAY NIGHT
INTO SUNDAY WITH HIGH PRESSURE BUILDING DOWN THE PLAINS.
JEE
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...GALE WARNING...LMZ080-LMZ567-LMZ669-LMZ671-LMZ673-LMZ675-LMZ744-
LMZ745-LMZ777-LMZ779-LMZ868-LMZ870-LMZ872-LMZ874-LMZ876-
LMZ878 UNTIL 9 PM TUESDAY.
SMALL CRAFT ADVISORY...NEARSHORE WINTHROP HARBOR TO GARY IN UNTIL
MIDNIGHT WEDNESDAY.
&&
$$
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AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
557 AM CST TUE DEC 17 2013
.DISCUSSION...
328 AM CST
TODAY...
MAIN CONCERNS WILL BE FOCUSED ON THE MID-LVL WAVE THAT IS QUICKLY
SLIDING EAST ACROSS THE WESTERN GREAT LAKES...POSSIBLY BRINGING A
SLUG OF LGT SNOW TO NORTH/NORTHEAST IL AND NORTHWEST IN THIS MORNING
THRU MIDDAY. THEN THE POTENTIAL FOR SOME BLOWING SNOW AS THE
GRADIENT RAMPS UP MIDDAY AND MIXING JUMPS TO ARND 3KFT AGL.
IR IMAGERY SHOWS CONSIDERABLE CLOUD COVER ACROSS THE REGION...AND
SOME COOLING WITH CLOUD TOPS WITH THE WEAK WAVE SLIDING EAST ACROSS
WESTCENTRAL WISC EARLY THIS MORNING. KARX RADAR INDICATES AN AREA OF
RETURNS ACROSS THIS AREA...HOWEVER THE RECENT COUPLE OF HOURS HAVE
INDICATED SOME DOWNWARD TREND IN THE SOUTHERN PORTION OF THIS
PRECIP. SFC OBS ARE NOT INDICATING ANY SNOW IN FAR SOUTHEAST MN AND
HAS TENDED TO BE FOCUSED FURTHER NORTH. BASED ON CURRENT
TRAJECTORY...THE BEST LGT SNOW MAY END UP HOLDING FURTHER NORTH INTO
WISC. BUFR PROFILES HAVE BACKED OFF ON THE OMEGA PLACEMENT...HOWEVER
A HANDFUL OF POINTS CONTINUE TO INDICATE SOME DEGREE OF LIFT THROUGH
THE FAVORED DGZ ARND 12-15Z. DPROG/DT OF THE BUFR SITES ALSO
INDICATES A DOWNWARD TREND...SUPPORTING THE LOWER CONFIDENCE IN SNOW
TOTALS. THE CAVEAT AND CHALLENGE IS THE NARROW CHANNEL OF MOISTURE
THAT STRETCHES WEST AND RECENT RAP GUIDANCE HAS INDICATED AN
ENHANCEMENT TO THIS FEATURE AS IT PIVOTS EAST ACROSS THE CWFA THIS
MORNING.
SNOWFALL RATIOS SHOULD FALL AROUND 20:1...SO RATHER DRY.
BASED ON COBB OUTPUT FROM THESE PROFILES SNOWFALL SHUD GENERALLY
FALL BETWEEN A FEW TENTHS TO 1". COULD SEE AREAS CLOSEST TO THE
WISCONSIN STATELINE PICKING UP SLIGHTLY MORE OR WITHIN A 1-2" RANGE.
THE WAVE WILL REMAIN PROGRESSIVE AND SHUD COME TO AN END BY 15-17Z
FROM WEST TO EAST...AS WIND GUSTS BEGIN TO DEVELOP. ANY FRESH
SNOWFALL SHUD EASILY BLOW AROUND. THIS MAY BE MORE FOCUSED ACROSS
AREAS NORTH OF I-80...AS THE PATCHY DZ EARLY THIS MORNING WILL
MOISTEN UP THE SNOW FURTHER SOUTH AND LIMIT THE ABILITY FOR THE SNOW
TO BLOW AROUND.
TEMPS WILL BEGIN TO REBOUND TDY...AS THE 500MB TROUGH AXIS BEGINS TO
PUSH EAST OF THE WESTERN GREAT LAKES. TEMPS WILL STEADILY WARM INTO
THE UPR 20S TO ARND 30 ACROSS THE SOUTHERN CWFA.
CONFIDENCE IN SNOWFALL...MEDIUM/LOW.
CONFIDENCE IN TEMPS...HIGH.
TONIGHT THROUGH WEDNESDAY...
500MB HEIGHTS BEGIN TO RISE THIS EVENING WITH DIFFLUENT FLOW LIFTING
NORTH FROM THE SFC RIDGE CENTERED ACROSS THE OZARKS. THIS SHUD AID
IN ERODING SOME OF THE CLOUD COVER...AND COULD SEE P-CLOUDY SKIES
FOR A BRIEF PERIOD OVERNIGHT. THEN ANOTHER WEAK MID-LVL WAVE IS
PROGGED TO BUMP INTO THE DIFFLUENT FLOW AND BRING SOME MID-LVL
MOISTURE AND CLOUDS BACK TO THE AREA DURING THE OVERNIGHT HOURS.
500MB FLOW CONTINUES TO EVOLVE INTO A ZONAL SETUP...ALTHOUGH THIS
WILL ONLY BE TEMPORARY THRU WED. SFC RIDGE ACROSS THE OZARKS DRIFTS
EAST TOWARDS THE MID-ATLANTIC/GULF STATES...WITH LLVL FLOW TURNING
SOUTH/SOUTHWEST FOR THE CWFA.
FOR THE FIRST TIME IN SEVERAL DAYS WED MAY SEE THE 850MB 0 DEG
ISOTHERM LIFT OVERHEAD ALONG THE LEADING EDGE OF INCREASED WARM AIR
ADVECTION. THE MID-LVL THERMAL RIDGE CONTINUES TO WARM FURTHER SOUTH
WITH TEMPS RISING TO NEAR 9 DEG C OVER NORTHERN MISSOURI WED AFTN.
GIVEN THE EXPANSIVE SNOW COVER...THE CHALLENGE IS HOW WARM WILL WED
END UP BECOMING. GUIDANCE HAS TRENDED SLIGHTLY COOLER OVER THE PAST
FEW DAYS WITH WED HIGHS. AT THIS TIME THE GENERAL CONSENSUS HAS BEEN
ON TEMPS IN THE LOW 30S ALONG/NORTH OF I-80 AND POINTS SOUTH
POSSIBLY REACHING THE MID 30S.
WITH DEW POINTS PROGGED TO BE RISING TO ARND FREEZING...THE SNOWMELT
RATES WILL RAMP UP. WITH THE ADDED MOISTURE COUPLED WITH A
MOISTENING MID/UPR LVLS AHEAD OF THE NEXT WEATHER SYSTEM...THE
ENVIRONMENT SEEMS PRIMED FOR THE DEVELOPMENT OF PATCHY/AREAS OF FOG.
FREQUENTLY MELTING SNOW CAN PRODUCE SHALLOW DENSE FOG...SO THIS WILL
CONTINUE TO BE THE FOCUS WED NGT.
CONFIDENCE IN TEMPS...MEDIUM.
CONFIDENCE IN FOG DEVELOPING WED NGT...HIGH.
THURSDAY THROUGH SATURDAY...
MID-LVL FLOW CONTINUES TO PROGRESS INTO A SOUTHWEST SETUP WITH A
500MB VORT MAX PUSHING INTO THE FOUR-CORNERS REGION THUR. SFC
RIDGING IN THE LLVLS WILL BE PARKED OVER THE SOUTHEASTERN
CONUS...ALLOWING FOR CONTINUED FEED OF WARM AIR ADVECTING NORTH
THROUGH THE OZARKS INTO THE OHIO VALLEY/GREAT LAKES REGIONS THUR.
GUIDANCE CONTINUES TO FEATURE A WAVE DEVELOPING ALONG THE LEE-SIDE
OF THE ROCKIES THUR...AS A WEAK SFC RIDGE SAGS SOUTH FROM CENTRAL
CANADA INTO THE UPPER MIDWEST AND SHARPENS UP A BAROCLINIC ZONE OVER
THE NORTHERN PLAINS STRETCHING NORTHEAST THROUGH THE UPPER PENINSULA
OF MICHIGNA. THIS WILL LIKELY KEEP THE WARM AIR OVER THE CWFA
THUR...AND ANY PRECIP WILL LIKELY FALL AS LIQUID THUR. AT THE ONSET
THUR MORNING A BRIEF PERIOD OF FZDZ/FZRA MAY OCCUR...HOWEVER THIS
WILL LIKELY BE BRIEF. GUIDANCE HAS TRENDED SLIGHTLY FURTHER SOUTH
WITH THE SFC LOW FOR THUR NIGHT...AS THE 850MB LOW IS PROGGED TO
SLIDE OVER SOUTHCENTRAL WISC.
WITH SOME DEGREE OF UNCERTAINTY REMAINING IN THE PLACEMENT OF THE
SFC LOW...THIS OPENS UP DECREASED CONFIDENCE IN HIGH TEMPS FOR THUR.
A FURTHER NORTH PATH WOULD PROVIDE TEMPS IN THE MID/UPR
30S...MEANWHILE A CORRECTION TO THE SOUTH WOULD KEEP TEMPS ARND 30
TO LOW 30S. FURTHER COMPOUNDING THIS WOULD BE THE THEN POTENTIAL FOR
P-TYPE ISSUES.
THE SFC RIDGE ACROSS THE UPPER MIDWEST SHUD HELP TO PUSH THE
BAROCLINIC BOUNDARY SOUTH FOR FRI...AS THE LOW LIFTS NORTHEAST OF
THE FORECAST AREA. THIS SHUD AID IN COOLER AIR FILTERING IN BEHIND
AND PUSHING DEW POINTS BACK INTO THE 20S. P-TYPE FOR FRI SHUD BE
LIMITED TO RA/SN...AND TRANSITION TO ALL SN BY FRI AFTN/EVE.
500MB VORT MAX ACROSS THE FAR SOUTHWEST CONUS WILL BEGIN TO DIG
SOUTHEAST OF NEW MEXICO...WHICH WILL LIKELY TRANSLATE IN THE
DOWNSTREAM BOUNDARY SAGGING FURTHER SOUTH THROUGH THE OHIO VALLEY
FRI NGT. THEN YET ANOTHER WAVE IS PROGGED TO DEVELOP ACROSS EASTERN
TEXAS AND TAKE A CLASSIC TRAJECTORY TOWARDS THE OHIO VALLEY FOR THE
SECOND HALF OF THE WEEKEND.
CONFIDENCE IN TEMPS...MEDIUM/HIGH.
SUNDAY THROUGH EARLY CHRISTMAS WEEK...
ENSEMBLES INDICATE A SIMILAR COLD SETUP FOR THE SECOND HALF OF THE
WEEKEND INTO EARLY CHRISTMAS WEEK. WESTERN MID-LVL RIDGE MAY BEGIN
TO AMPLIFY FOR EARLY NEXT WEEK...RESULTING IN A DOWNSTREAM TROUGH
POSITIONED OVER THE GREAT LAKES REGION. OPERATIONAL SOLUTIONS
CONTINUE TO POINT TOWARDS A ROBUST WEATHER SYSTEM SUN LIFTING
NORTHEAST ACROSS THE REGION FROM THE SOUTHERN PLAINS/EASTERN
TEXAS...WITH TEMPS COLD ENOUGH TO SUPPORT ALL SNOW FOR THIS EVENT.
THEN ON THE BACKSIDE OF THIS MUCH COLDER AIR POURS BACK INTO THE
CWFA WITH TEMPS ALOFT RETURNING TO -10 TO -14 DEG C AT 850MB FOR
EARLY CHRISTMAS WEEK. THIS WILL KEEP SFC TEMPS IN THE UPPER TEENS TO
LOW 20S.
CONFIDENCE IN SUNDAY SYSTEM...HIGH.
CONFIDENCE IN TEMPS...MEDIUM/HIGH.
BEACHLER
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 12Z...
* IFR CIGS WITH LOW END VFR VSBY THIS MORNING. IFR CIGS PERSIST
THROUGH THE SNOWFALL.
* SNOW RETURNS ARND 13Z WITH VSBY DROPPING TO AROUND A MILE. BRIEF
REDUCTIONS TO BELOW 1 SM AND 500 FT CIGS AFTER 14Z.
* STRONG WEST WINDS SET UP LATE IN THE MORNING THROUGH THE
AFTN...20 KT GUSTING TO ARND 30 KT.
* GUSTY SOUTH WINDS EXPECTED TOMORROW AFTERNOON.
JEE
//DISCUSSION...UPDATED 12Z...
IFR CIGS HAVE SPREAD ACROSS THE TERMINALS AS THE LOW PRESSURE
TROUGH APPROACHES FROM THE WEST. THE MAIN LOW WILL PASS TO OUR
NORTH THROUGH ONTARIO TODAY...WITH ITS COLD FRONT SWINGING THROUGH
THIS AFTN. A BAND OF SNOW HAS FORMED OVER SOUTHERN WI AND
EXPECTING IT TO REACH RFD ARND 1230Z...THEN AT ORD BY 13Z. UNTIL
THEN...EXPECTING CONDITIONS TO STAY RIGHT WHERE THEY ARE. IFR
CIGS AND VFR/MVFR VSBY. WHEN THE SNOW ARRIVES...VSBYS WILL FALL
FURTHER TO AROUND A MILE. THERE SHOULD BE A BRIEF PERIOD OF
HEAVIER SNOW WITH VSBYS BELOW 1 MILE.
WINDS PICK UP AFTER THE COLD FRONT WITH GUSTS AROUND 30 KT. KEPT
MVFR CIGS GOING...BUT GUIDANCE SUGGESTS MVFR OR LOWER CIGS COULD
HANG AROUND LONGER THAN CURRENTLY FORECAST. BLOWING SNOW WILL
LIKELY BE AN ISSUE GIVEN THE FRESH LIGHT SNOW. NOT EXPECTING IT TO
IMPACT VSBY THOUGH.
HIGH PRESSURE PASSES TO THE SOUTH OVERNIGHT WITH WINDS BECOMING
SOUTHWEST AROUND 10 KT. WINDS TURN FURTHER SOUTH AND BEGIN GUSTING
TO AROUND 20 KT IN THE LATE MORNING...BUT EXPECTING VFR CONDITIONS.
JEE
//ORD AND MDW CONFIDENCE...UPDATED 12Z...
* HIGH CONFIDENCE IN FORECAST THROUGH 16Z.
* MEDIUM CONFIDENCE IN HOW QUICKLY CIGS WILL LIFT BEHIND THE SNOW.
* MEDIUM CONFIDENCE THAT BLOWING SNOW WILL NOT IMPACT VSBYS.
* HIGH CONFIDENCE IN ALL OTHER FORECAST ELEMENTS.
JEE
//OUTLOOK FOR ORD/MDW FOR 00Z THURSDAY-12Z TUESDAY...UPDATED 12Z...
WEDNESDAY NIGHT...MVFR OR LOWER CIGS/VSBY PSBL.
THURSDAY...RAIN AND FOG. MVFR OR LOWER.
FRIDAY...CHC RAIN OR SNOW BECOMING ALL SNOW BY THE AFTN. MVFR OR
LOWER.
SATURDAY...SNOW. MVFR OR LOWER.
SUNDAY...SNOW DURING THE DAY. MVFR PSBL.
MONDAY...VFR.
JEE
&&
.MARINE...
306 AM CST
FIRST OF ALL MADE NO CHANGES TO THE ONGOING HEADLINES AS THEY ALL
SEEM ON TRACK. A SMALL CRAFT ADVISORY WILL BE NEEDED FOR THE INDIANA
NEARSHORE WATERS AFTER THE GALE WARNING DUE TO LINGERING HAZARDOUS
WAVES.
LOW PRESSURE IS OVER ONTARIO AND IT WILL SLIDE TO THE EAST
TODAY...WHILE ITS COLD FRONT PASSES OVER THE LAKE THIS AFTERNOON.
AT THE SAME TIME HIGH PRESSURE BUILDS OVER THE CENTRAL PLAINS. THIS
WILL TIGHTEN THE PRESSURE GRADIENT OVER THE SOUTHERN END OF THE
LAKE...RESULTING IN LOW END GALES FORMING THIS MORNING THROUGH EARLY
THIS EVENING. WEST WINDS DIMINISH TO ARND 20 KT BY WEDNESDAY
MORNING AS HIGH PRESSURE PASSES TO THE SOUTH. WINDS PICK BACK UP ON
THE BACKSIDE OF THE HIGH LATE WEDNESDAY AFTERNOON INTO WEDNESDAY
EVENING. A BRIEF PERIOD OF SW GALES TO 35 KT IS POSSIBLE DURING
THAT TIME. A SMALL CRAFT ADVISORY WILL LIKELY BE NEEDED AS WELL FOR
WEDNESDAY AFTERNOON AND EVENING. WINDS WEAKEN WEDNESDAY NIGHT AS A
TROUGH OF LOW PRESSURE SITS OVER THE LAKE WEDNESDAY NIGHT THROUGH
THURSDAY. THE NEXT WEAK LOW MOVES OVER THE LAKE THURSDAY NIGHT
BEFORE SHIFTING EAST ON FRIDAY. WINDS TURN LIGHT AND VARIABLE
BEHIND THE LOW ON SATURDAY...BUT THEN TURN NORTH AND STRENGTHEN
SATURDAY NIGHT INTO SUNDAY IN RESPONSE TO THE NEXT SYSTEM. GUIDANCE
FEATURES ANOTHER LOW PUSHING UP THE OHIO RIVER VALLEY SATURDAY NIGHT
INTO SUNDAY WITH HIGH PRESSURE BUILDING DOWN THE PLAINS.
JEE
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...GALE WARNING...LMZ080-LMZ567-LMZ669-LMZ671-LMZ673-LMZ675-LMZ744-
LMZ745-LMZ777-LMZ779-LMZ868-LMZ870-LMZ872-LMZ874-LMZ876-
LMZ878...9 AM TUESDAY TO 9 PM TUESDAY.
SMALL CRAFT ADVISORY...LMZ740-LMZ741-LMZ742-LMZ743...9 AM
TUESDAY TO MIDNIGHT WEDNESDAY.
&&
$$
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AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
329 AM CST TUE DEC 17 2013
.DISCUSSION...
328 AM CST
TODAY...
MAIN CONCERNS WILL BE FOCUSED ON THE MID-LVL WAVE THAT IS QUICKLY
SLIDING EAST ACROSS THE WESTERN GREAT LAKES...POSSIBLY BRINGING A
SLUG OF LGT SNOW TO NORTH/NORTHEAST IL AND NORTHWEST IN THIS MORNING
THRU MIDDAY. THEN THE POTENTIAL FOR SOME BLOWING SNOW AS THE
GRADIENT RAMPS UP MIDDAY AND MIXING JUMPS TO ARND 3KFT AGL.
IR IMAGERY SHOWS CONSIDERABLE CLOUD COVER ACROSS THE REGION...AND
SOME COOLING WITH CLOUD TOPS WITH THE WEAK WAVE SLIDING EAST ACROSS
WESTCENTRAL WISC EARLY THIS MORNING. KARX RADAR INDICATES AN AREA OF
RETURNS ACROSS THIS AREA...HOWEVER THE RECENT COUPLE OF HOURS HAVE
INDICATED SOME DOWNWARD TREND IN THE SOUTHERN PORTION OF THIS
PRECIP. SFC OBS ARE NOT INDICATING ANY SNOW IN FAR SOUTHEAST MN AND
HAS TENDED TO BE FOCUSED FURTHER NORTH. BASED ON CURRENT
TRAJECTORY...THE BEST LGT SNOW MAY END UP HOLDING FURTHER NORTH INTO
WISC. BUFR PROFILES HAVE BACKED OFF ON THE OMEGA PLACEMENT...HOWEVER
A HANDFUL OF POINTS CONTINUE TO INDICATE SOME DEGREE OF LIFT THROUGH
THE FAVORED DGZ ARND 12-15Z. DPROG/DT OF THE BUFR SITES ALSO
INDICATES A DOWNWARD TREND...SUPPORTING THE LOWER CONFIDENCE IN SNOW
TOTALS. THE CAVEAT AND CHALLENGE IS THE NARROW CHANNEL OF MOISTURE
THAT STRETCHES WEST AND RECENT RAP GUIDANCE HAS INDICATED AN
ENHANCEMENT TO THIS FEATURE AS IT PIVOTS EAST ACROSS THE CWFA THIS
MORNING.
SNOWFALL RATIOS SHOULD FALL AROUND 20:1...SO RATHER DRY.
BASED ON COBB OUTPUT FROM THESE PROFILES SNOWFALL SHUD GENERALLY
FALL BETWEEN A FEW TENTHS TO 1". COULD SEE AREAS CLOSEST TO THE
WISCONSIN STATELINE PICKING UP SLIGHTLY MORE OR WITHIN A 1-2" RANGE.
THE WAVE WILL REMAIN PROGRESSIVE AND SHUD COME TO AN END BY 15-17Z
FROM WEST TO EAST...AS WIND GUSTS BEGIN TO DEVELOP. ANY FRESH
SNOWFALL SHUD EASILY BLOW AROUND. THIS MAY BE MORE FOCUSED ACROSS
AREAS NORTH OF I-80...AS THE PATCHY DZ EARLY THIS MORNING WILL
MOISTEN UP THE SNOW FURTHER SOUTH AND LIMIT THE ABILITY FOR THE SNOW
TO BLOW AROUND.
TEMPS WILL BEGIN TO REBOUND TDY...AS THE 500MB TROUGH AXIS BEGINS TO
PUSH EAST OF THE WESTERN GREAT LAKES. TEMPS WILL STEADILY WARM INTO
THE UPR 20S TO ARND 30 ACROSS THE SOUTHERN CWFA.
CONFIDENCE IN SNOWFALL...MEDIUM/LOW.
CONFIDENCE IN TEMPS...HIGH.
TONIGHT THROUGH WEDNESDAY...
500MB HEIGHTS BEGIN TO RISE THIS EVENING WITH DIFFLUENT FLOW LIFTING
NORTH FROM THE SFC RIDGE CENTERED ACROSS THE OZARKS. THIS SHUD AID
IN ERODING SOME OF THE CLOUD COVER...AND COULD SEE P-CLOUDY SKIES
FOR A BRIEF PERIOD OVERNIGHT. THEN ANOTHER WEAK MID-LVL WAVE IS
PROGGED TO BUMP INTO THE DIFFLUENT FLOW AND BRING SOME MID-LVL
MOISTURE AND CLOUDS BACK TO THE AREA DURING THE OVERNIGHT HOURS.
500MB FLOW CONTINUES TO EVOLVE INTO A ZONAL SETUP...ALTHOUGH THIS
WILL ONLY BE TEMPORARY THRU WED. SFC RIDGE ACROSS THE OZARKS DRIFTS
EAST TOWARDS THE MID-ATLANTIC/GULF STATES...WITH LLVL FLOW TURNING
SOUTH/SOUTHWEST FOR THE CWFA.
FOR THE FIRST TIME IN SEVERAL DAYS WED MAY SEE THE 850MB 0 DEG
ISOTHERM LIFT OVERHEAD ALONG THE LEADING EDGE OF INCREASED WARM AIR
ADVECTION. THE MID-LVL THERMAL RIDGE CONTINUES TO WARM FURTHER SOUTH
WITH TEMPS RISING TO NEAR 9 DEG C OVER NORTHERN MISSOURI WED AFTN.
GIVEN THE EXPANSIVE SNOW COVER...THE CHALLENGE IS HOW WARM WILL WED
END UP BECOMING. GUIDANCE HAS TRENDED SLIGHTLY COOLER OVER THE PAST
FEW DAYS WITH WED HIGHS. AT THIS TIME THE GENERAL CONSENSUS HAS BEEN
ON TEMPS IN THE LOW 30S ALONG/NORTH OF I-80 AND POINTS SOUTH
POSSIBLY REACHING THE MID 30S.
WITH DEW POINTS PROGGED TO BE RISING TO ARND FREEZING...THE SNOWMELT
RATES WILL RAMP UP. WITH THE ADDED MOISTURE COUPLED WITH A
MOISTENING MID/UPR LVLS AHEAD OF THE NEXT WEATHER SYSTEM...THE
ENVIRONMENT SEEMS PRIMED FOR THE DEVELOPMENT OF PATCHY/AREAS OF FOG.
FREQUENTLY MELTING SNOW CAN PRODUCE SHALLOW DENSE FOG...SO THIS WILL
CONTINUE TO BE THE FOCUS WED NGT.
CONFIDENCE IN TEMPS...MEDIUM.
CONFIDENCE IN FOG DEVELOPING WED NGT...HIGH.
THURSDAY THROUGH SATURDAY...
MID-LVL FLOW CONTINUES TO PROGRESS INTO A SOUTHWEST SETUP WITH A
500MB VORT MAX PUSHING INTO THE FOUR-CORNERS REGION THUR. SFC
RIDGING IN THE LLVLS WILL BE PARKED OVER THE SOUTHEASTERN
CONUS...ALLOWING FOR CONTINUED FEED OF WARM AIR ADVECTING NORTH
THROUGH THE OZARKS INTO THE OHIO VALLEY/GREAT LAKES REGIONS THUR.
GUIDANCE CONTINUES TO FEATURE A WAVE DEVELOPING ALONG THE LEE-SIDE
OF THE ROCKIES THUR...AS A WEAK SFC RIDGE SAGS SOUTH FROM CENTRAL
CANADA INTO THE UPPER MIDWEST AND SHARPENS UP A BAROCLINIC ZONE OVER
THE NORTHERN PLAINS STRETCHING NORTHEAST THROUGH THE UPPER PENINSULA
OF MICHIGNA. THIS WILL LIKELY KEEP THE WARM AIR OVER THE CWFA
THUR...AND ANY PRECIP WILL LIKELY FALL AS LIQUID THUR. AT THE ONSET
THUR MORNING A BRIEF PERIOD OF FZDZ/FZRA MAY OCCUR...HOWEVER THIS
WILL LIKELY BE BRIEF. GUIDANCE HAS TRENDED SLIGHTLY FURTHER SOUTH
WITH THE SFC LOW FOR THUR NIGHT...AS THE 850MB LOW IS PROGGED TO
SLIDE OVER SOUTHCENTRAL WISC.
WITH SOME DEGREE OF UNCERTAINTY REMAINING IN THE PLACEMENT OF THE
SFC LOW...THIS OPENS UP DECREASED CONFIDENCE IN HIGH TEMPS FOR THUR.
A FURTHER NORTH PATH WOULD PROVIDE TEMPS IN THE MID/UPR
30S...MEANWHILE A CORRECTION TO THE SOUTH WOULD KEEP TEMPS ARND 30
TO LOW 30S. FURTHER COMPOUNDING THIS WOULD BE THE THEN POTENTIAL FOR
P-TYPE ISSUES.
THE SFC RIDGE ACROSS THE UPPER MIDWEST SHUD HELP TO PUSH THE
BAROCLINIC BOUNDARY SOUTH FOR FRI...AS THE LOW LIFTS NORTHEAST OF
THE FORECAST AREA. THIS SHUD AID IN COOLER AIR FILTERING IN BEHIND
AND PUSHING DEW POINTS BACK INTO THE 20S. P-TYPE FOR FRI SHUD BE
LIMITED TO RA/SN...AND TRANSITION TO ALL SN BY FRI AFTN/EVE.
500MB VORT MAX ACROSS THE FAR SOUTHWEST CONUS WILL BEGIN TO DIG
SOUTHEAST OF NEW MEXICO...WHICH WILL LIKELY TRANSLATE IN THE
DOWNSTREAM BOUNDARY SAGGING FURTHER SOUTH THROUGH THE OHIO VALLEY
FRI NGT. THEN YET ANOTHER WAVE IS PROGGED TO DEVELOP ACROSS EASTERN
TEXAS AND TAKE A CLASSIC TRAJECTORY TOWARDS THE OHIO VALLEY FOR THE
SECOND HALF OF THE WEEKEND.
CONFIDENCE IN TEMPS...MEDIUM/HIGH.
SUNDAY THROUGH EARLY CHRISTMAS WEEK...
ENSEMBLES INDICATE A SIMILAR COLD SETUP FOR THE SECOND HALF OF THE
WEEKEND INTO EARLY CHRISTMAS WEEK. WESTERN MID-LVL RIDGE MAY BEGIN
TO AMPLIFY FOR EARLY NEXT WEEK...RESULTING IN A DOWNSTREAM TROUGH
POSITIONED OVER THE GREAT LAKES REGION. OPERATIONAL SOLUTIONS
CONTINUE TO POINT TOWARDS A ROBUST WEATHER SYSTEM SUN LIFTING
NORTHEAST ACROSS THE REGION FROM THE SOUTHERN PLAINS/EASTERN
TEXAS...WITH TEMPS COLD ENOUGH TO SUPPORT ALL SNOW FOR THIS EVENT.
THEN ON THE BACKSIDE OF THIS MUCH COLDER AIR POURS BACK INTO THE
CWFA WITH TEMPS ALOFT RETURNING TO -10 TO -14 DEG C AT 850MB FOR
EARLY CHRISTMAS WEEK. THIS WILL KEEP SFC TEMPS IN THE UPPER TEENS TO
LOW 20S.
CONFIDENCE IN SUNDAY SYSTEM...HIGH.
CONFIDENCE IN TEMPS...MEDIUM/HIGH.
BEACHLER
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 09Z...
* IFR CIGS WITH PERIODS OF MVFR VSBY ARE EXPECTED UNTIL THE SNOW
STARTS.
* SNOW RETURNS ARND 13Z WITH VSBY DROPPING TO AROUND A MILE. BRIEF
REDUCTIONS TO BELOW 1 SM PSBL.
* STRONG WEST WINDS SET UP LATE IN THE MORNING THROUGH THE
AFTN...20 KT GUSTING TO ARND 30 KT.
JEE
//DISCUSSION...UPDATED 06Z...
A LOW PRESSURE TROUGH IS OVER THE REGION WITH THE PARENT LOW OVER
SOUTH CENTRAL CANADA. ANOTHER UPPER LEVEL WAVE WILL APPROACH FROM
THE NW EARLY THIS MORNING KICKING OFF MORE SNOW. CIGS ARE
CURRENTLY MVFR WITH THE ONLY IFR SITES BEING RFD AND GYY. NOT SURE
HOW THE WIDESPREAD IFR CIGS WEST AND SOUTH OF THE TERMINALS ARE
STAYING OUT OF THE TERMINALS...BUT BETTING NO ONE IS COMPLAINING.
WHILE THE OBS ARE NOT SHOWING IFR...KEPT THE TEMPOS GOING WITH IFR
THROUGH THE MORNING. VSBYS HAVE ALSO COME UP WITH THE FOG
REMAINING ALSO TO THE SOUTH AND WEST OF THE TERMINALS. THIS IS
PROBABLY DUE TO THE SLIGHTLY DRIER AIR OVER THE TERMINALS.
WEST WINDS WILL PICK UP AS THE GRADIENT TIGHTENS...SO THINKING ALL
SITES OTHER THAN RFD SHOULD REMAIN VFR OVERNIGHT. THE SNOW ARRIVES
AROUND DAYBREAK AT RFD AND IT SHOULD BE ANOTHER QUICK SYSTEM.
FORCING LOOKS DECENT IN THE SNOW GROWTH ZONE...SO THINKING 1 1/2SM
IS STILL REASONABLE. MAY SEE A BRIEF PERIOD OF HEAVIER AND LESS
THAN 1 SM VSBY...BUT NOT ENTIRELY SURE WHERE IN THE SNOW WINDOW
THIS WOULD OCCUR. WILL LIKELY ADD A TEMPO FOR REDUCED VSBY LATER.
WINDS REALLY RAMP UP BY MID MORNING WITH GUSTS ARND 30 KT
EXPECTED. THE ADDED MIXING WILL HELP LIFT CIGS TO VFR WITH VFR
CONDITIONS EXPECTED FOR THE REST OF THE PERIOD. GUSTS DIMINISH IN
THE AFTN WITH WINDS BCMG SW BY WEDNESDAY MORNING.
JEE
//ORD AND MDW CONFIDENCE...UPDATED 09Z...
* MEDIUM-LOW CONFIDENCE IN HOW LONG CURRENT IFR CIGS AND MVFR VSBY
WILL PERSIST.
* HIGH CONFIDENCE IN SNOW OCCURRING.
* MEDIUM CONFIDENCE ON HOW LOW VSBY WILL GET WITH SNOW.
* HIGH CONFIDENCE IN ALL OTHER FORECAST ELEMENTS.
JEE
//OUTLOOK FOR ORD/MDW FOR 12Z WEDNESDAY-12Z MONDAY...UPDATED 00Z...
WEDNESDAY...VFR.
THURSDAY...CHANCE OF RAIN W/ FOG.
FRIDAY...CHANCE OF RAIN OR SNOW BECOMING ALL SNOW BY THE
AFTERNOON.
SATURDAY...CHANCE OF SNOW.
SUNDAY...CHANCE OF SNOW.
RODRIGUEZ
&&
.MARINE...
306 AM CST
FIRST OF ALL MADE NO CHANGES TO THE ONGOING HEADLINES AS THEY ALL
SEEM ON TRACK. A SMALL CRAFT ADVISORY WILL BE NEEDED FOR THE INDIANA
NEARSHORE WATERS AFTER THE GALE WARNING DUE TO LINGERING HAZARDOUS
WAVES.
LOW PRESSURE IS OVER ONTARIO AND IT WILL SLIDE TO THE EAST
TODAY...WHILE ITS COLD FRONT PASSES OVER THE LAKE THIS AFTERNOON.
AT THE SAME TIME HIGH PRESSURE BUILDS OVER THE CENTRAL PLAINS. THIS
WILL TIGHTEN THE PRESSURE GRADIENT OVER THE SOUTHERN END OF THE
LAKE...RESULTING IN LOW END GALES FORMING THIS MORNING THROUGH EARLY
THIS EVENING. WEST WINDS DIMINISH TO ARND 20 KT BY WEDNESDAY
MORNING AS HIGH PRESSURE PASSES TO THE SOUTH. WINDS PICK BACK UP ON
THE BACKSIDE OF THE HIGH LATE WEDNESDAY AFTERNOON INTO WEDNESDAY
EVENING. A BRIEF PERIOD OF SW GALES TO 35 KT IS POSSIBLE DURING
THAT TIME. A SMALL CRAFT ADVISORY WILL LIKELY BE NEEDED AS WELL FOR
WEDNESDAY AFTERNOON AND EVENING. WINDS WEAKEN WEDNESDAY NIGHT AS A
TROUGH OF LOW PRESSURE SITS OVER THE LAKE WEDNESDAY NIGHT THROUGH
THURSDAY. THE NEXT WEAK LOW MOVES OVER THE LAKE THURSDAY NIGHT
BEFORE SHIFTING EAST ON FRIDAY. WINDS TURN LIGHT AND VARIABLE
BEHIND THE LOW ON SATURDAY...BUT THEN TURN NORTH AND STRENGTHEN
SATURDAY NIGHT INTO SUNDAY IN RESPONSE TO THE NEXT SYSTEM. GUIDANCE
FEATURES ANOTHER LOW PUSHING UP THE OHIO RIVER VALLEY SATURDAY NIGHT
INTO SUNDAY WITH HIGH PRESSURE BUILDING DOWN THE PLAINS.
JEE
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...GALE WARNING...LMZ080-LMZ567-LMZ669-LMZ671-LMZ673-LMZ675-LMZ744-
LMZ745-LMZ777-LMZ779-LMZ868-LMZ870-LMZ872-LMZ874-LMZ876-
LMZ878...9 AM TUESDAY TO 9 PM TUESDAY.
SMALL CRAFT ADVISORY...LMZ740-LMZ741-LMZ742-LMZ743...9 AM
TUESDAY TO MIDNIGHT WEDNESDAY.
&&
$$
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WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
309 AM CST TUE DEC 17 2013
.DISCUSSION...
830 PM CST
CHARACTERISTIC OF THIS YOUNG 2013-2014 WINTER...ONE WEATHER ISSUE
DEPARTS AND ANOTHER QUICKLY FOLLOWS ON ITS HEELS. NOT ONLY IS THAT
NEXT ISSUE THE BRIEF SHOT OF SNOW TUESDAY MORNING...BUT ALSO
FREEZING FOG FOR AREAS ALONG AND SOUTH OF HIGHWAY 24 DURING THIS
EVENING. WE ISSUED A SPECIAL WEATHER STATEMENT FOR BOTH.
GOES WATER VAPOR SATELLITE AND UPPER AIR ANALYSES INDICATE THE
SHORT WAVE OF THE EARLIER SNOW IS HEADING EAST OVER LAKE MI ON A
STRONG 80 KT 500MB JET MAX. THE MAIN PRESSURE FALLS ARE LOCATED
EVEN FURTHER NORTH ACROSS THE FAR NORTHERN GREAT LAKES...SO THE
SURFACE REFLECTION ACROSS OUR AREA HAS BEEN WEAK. THIS HAS HELPED
ALLOW FOR SATURATION IN THE LOW-LEVELS AND THE INABILITY TO ADVECT
IT AWAY. BOTH THE 00Z DVN AND ILX SOUNDINGS SHOWED STRONG
INVERSIONS OF AROUND 7C WITH NEARLY COMPLETE SATURATION BELOW.
SATELLITE AND OBSERVATIONS CORRELATE WITH THIS LOW-LEVEL MOISTURE
WELL...DEPICTING LOW VISIBILITIES ACROSS CENTRAL IL.
LAW ENFORCEMENT HAS REPORTED THIS ALONG WITH ICY ROADS IN FORD AND
BENTON COUNTIES AS TEMPERATURES ARE WELL BELOW FREEZING. ITS NOT
IMPOSSIBLE THERE IS A LITTLE DRIZZLE IN THIS MUCK AS WELL GIVEN
THE DECENT WIND FLOW AND SLIGHT ASCENT AT AND JUST ABOVE THE
INVERSION LEVEL. EVENTUALLY WESTERLY SURFACE WINDS DO INCREASE
SOME AS THE PRESSURE GRADIENT TIGHTENS OVERNIGHT. RAP AND HRRR
VISIBILITY AND CIG FORECAST DO TRY TO SHOW THE VERY LOW SATURATION
ADVECTING EAST BY EARLY OVERNIGHT AND THAT SEEMS
REASONABLE...THOUGH THEY COULD BE A LITTLE HASTY WITH THAT. GIVEN
THE SOMEWHAT LIMITED EXPECTED DURATION AND REPORTS OF VISIBILITY
NOT BEING AS LOW AS ONE QUARTER MILE IN OUR FORECAST AREA...HAVE
JUST GONE WITH AN SPS AS OPPOSED TO AN ADVISORY.
NEXT QUICK MOVING CLIPPER IS SEEN IN NW MN ON WATER VAPOR AND IS
ON A PATH FOR THE CWA BY DAYBREAK. THE GOING TIMING IN THE GRIDS
LOOKS GREAT COMPARED TO SHORT TERM/HIGH RES GUIDANCE WHICH SEEMED
TO HAVE HANDLED TODAYS SIMILAR EVENT WELL. RATIOS LOOK HIGHER WITH
THE TUE MORNING EVENT THAN TODAY...AND THE LATEST LOCAL 8KM ARW
DOES SHOW A COUPLE HOURS OF NEAR 25:1 RATIOS WHICH MAY BE A BIT
HIGH...BUT DO AT LEAST INDICATE THAT BURST POTENTIAL DURING RUSH
HOUR. TIMING AND MAGNITUDE OF WIND GUST INCREASE STILL LOOKS
REPRESENTATIVE AND THE FORECAST SPEEDS SHOULD BE ENOUGH TO
REALIZE PATCHY BLOWING OF THE FRESH SNOWFALL IN OPEN AREAS.
MTF
//PREV DISCUSSION...
305 PM CST
NUMEROUS FORECAST CONCERNS GOING THROUGH THE WEEKEND AS THE UPPER
FLOW PATTERN SHIFTS FROM FAVORING NORTHWEST FLOW AND PERIODIC
CLIPPERS TO A SOUTHWESTERLY FLOW SUPPORTING A BRIEF WARM UP FOLLOWED
BY THE POTENTIAL FOR STRONGER SOUTHWEST SYSTEMS.
EARLY AFTERNOON WATER VAPOR IMAGERY SHOWS A BROAD TROUGH OVER MOST
OF THE U.S. WITH BROAD RIDGING COMING OVER THE WEST COAST OF NORTH
AMERICA. EMBEDDED IN THE BROAD TROUGH ARE A SERIES OF WAVES...THE
FIRST OF WHICH IS ENTERING THE LOCAL AREA BRINGING BANDS OF SNOW.
THE NEXT WAVE OF NOTE IS MORE SUBTLE AS IT MOVES SOUTHEAST ACROSS
THE CENTRAL ALBERTA/SASKATCHEWAN BORDER AND GENERATES SNOW INTO
NORTHEASTERN MONTANA. THIS WAVE WILL MOVE INTO THE LOCAL AREA
TOMORROW MORNING. OTHERWISE...THE PATTERN WILL BECOME LESS AMPLIFIED
DURING MID WEEK AS THE MAIN UPPER TROUGH PUSHES EAST FOLLOWED BY THE
BROAD RIDGING CURRENTLY TO THE WEST.
TONIGHT AND TUESDAY...THE CURRENT CLIPPER WILL BE DEPARTING THE AREA
THROUGH THE EARLY EVENING HOURS BRINGING SNOW TO AN END AND TURNING
WINDS WESTERLY. ATTENTION TURNS TO THE MORE SUBTLE WAVE MOVING
SOUTHEAST ACROSS THE CENTRAL ALBERTA/SASKATCHEWAN BORDER AND A
SURFACE LOW TO THE EAST OF THE WAVE OVER MANITOBA WHICH WILL ALSO
MOVE SOUTHEAST WITH THE CENTER TRACKING INTO WESTERN ONTARIO TUESDAY
MORNING. A COLD FRONT WILL TRAIL THE LOW AND PUSH ACROSS THE LOCAL
AREA DURING THE MORNING. ANOTHER ROUND OF SNOW WILL LIKELY ACCOMPANY
THE PASSAGE OF THE UPPER WAVE AND SURFACE COLD FRONT. GUIDANCE
CONTINUES TO SHOW A RANGE OF SOLUTIONS WITH THE EXTENT/AMOUNT OF THE
PRECIP ACROSS THE AREA BUT GENERALLY HAS BEEN MORE BULLISH WITH
SNOWFALL COVERAGE OVER THE AREA THAN EARLIER RUNS. THIS FALLS IN
LINE WITH THE OBSERVED TRENDS OF THE CLIPPER LAST NIGHT AND THE ONE
CURRENTLY CROSSING THE AREA AND SEE LITTLE TO SUPPORT HAVING
DIFFERENT EXPECTATIONS FOR THIS NEXT ONE. WILL CONTINUE WITH THE
HIGH POPS ACROSS THE NORTHERN QUARTER TO THIRD OF THE AREA...WITH
THE FOCUS FOR MOST INTENSE AND LONGEST DURATION OF SNOW ALONG AND
NORTH OF A ROCKFORD TO CHICAGO TO VALPARAISO LINE...WHILE LIGHTER
SNOW FALLS TO THE SOUTH OF THIS LINE. THE UPPER WAVE LOOKS TO BE
SLIGHTLY WEAKER THAN THE ONE CURRENTLY CROSSING THE AREA BUT DOES
LOOK TO STRENGTHEN A BIT AS IT APPROACHES IN CONJUNCTION WITH A
BETTER ALIGNMENT OF THE LEFT EXIT OF AN UPPER JET. MODEL GUIDANCE
SHOWS A RANGE OF SNOWFALL AMOUNTS FROM VERY LITTLE TO A FEW INCHES
AND EVEN DIFFERS IN THE MAGNITUDE OF FORCING RELATIVE TO THE FAVORED
CRYSTAL GROWTH REGION. AT THIS POINT FEEL THE BEST ROUTE IS TO STICK
WITH THE OBSERVED TRENDS OF RECENT CLIPPERS AND ACCOUNT FOR THE
EXPECTATION OF SOME BETTER ORGANIZATION OF THE UPPER WAVE AND
FAVORED JET PLACEMENT. WITH THIS IN MIND FEEL THAT IT IS LIKELY THAT
NORTHERN PORTIONS OF THE AREA WILL SEE ANOTHER 1 TO POSSIBLY 2 INCH
EVENT WITH HIGH SNOW RATIOS. STEEP MID LEVEL LAPSE RATES AND GOOD
FORCING IN THE SNOW GROWTH ZONE SIMILAR TO TODAY SUPPORT
ACCUMULATION RATES OF 0.5 TO 0.75 IN/HR. CONTINUED WITH A SNOW RATIO
OF 16-18:1 OVERALL. MAY BE ABLE TO USE AMOUNTS/RATIOS/RATES FROM THE
CURRENT SNOW TO BETTER REFINE FOR THE MORNING. TIMING-WISE...SNOW
SHOULD MOVE INTO THE NORTHWEST PART OF THE AREA TOWARD DAYBREAK AND
THE CHICAGO METRO RIGHT AROUND OR JUST AFTER DAYBREAK THEN EXIT TO
THE EAST DURING THE LATE MORNING HOURS. THE PASSAGE OF THE COLD
FRONT WILL BRING A SHIFT TO NORTHWEST WINDS WHICH WILL INCREASE WITH
GUSTS PUSHING 35-40 MPH FROM LATE MORNING THROUGH THE AFTERNOON
LEADING TO BLOWING SNOW. HIGHS SHOULD BE RIGHT AROUND 30...THOUGH
THERE COULD BE A SLIGHT DECREASE IN TEMPS IN THE AFTERNOON WITH SOME
COOL ADVECTION BUT CLEARING SKIES AND SUNSHINE MAY OFFSET THIS. LOWS
TUESDAY NIGHT SHOULD FALL INTO THE MID TEENS WITH WINDS DIMINISHING
AND TURNING SOUTHWEST.
WEDNESDAY THROUGH FRIDAY...THE UPPER TROUGH CARVED OUT BY THE SERIES
OF CLIPPERS WILL SWING TO THE EAST AND OFF THE NEW ENGLAND COAST
WEDNESDAY ALLOWING FOR BROAD UPPER RIDGING TO SPREAD ACROSS THE
U.S. THIS WILL BRING A PUSH OF MID LEVEL WARM ADVECTION TO THE
REGION WEDNESDAY INTO THURSDAY WITH H85 TEMPS WARMING TO AROUND +6C
OR SO AND H92 TEMPS WARMING JUST ABOVE 0C. THIS WILL ALLOW FOR
SURFACE WARMING AS WELL BUT SNOW COVER WILL BE ONE LIMITING FACTOR.
TEMPS WEDNESDAY WILL BE TRICKY BECAUSE ASIDE FROM SOME MID LEVEL WAA
CLOUDS EARLY THERE WILL LIKELY BE AT LEAST SOME SUN AS WELL AS A
STRONG SOUTHWEST WIND. BOTH OF THESE POINT TOWARD WARMER HIGHS GIVEN
THAT THE LOWER ATMOSPHERE WILL STILL BE RELATIVELY DRY. THIS SHOULD
ALLOW MOST AREAS TO WARM TO OR JUST ABOVE FREEZING. BY THURSDAY...AN
UPPER TROUGH WILL BE WORKING INTO THE WESTERN U.S. WITH THE UPPER
FLOW SPLITTING INTO TWO STREAMS AS THE TROUGH DIGS SOUTH AND CUTS
OFF OVER OR JUST OFF THE CALIFORNIA COAST. HEIGHT FALLS AHEAD OF
THIS TROUGHING WILL LEAD TO SURFACE LOW PRESSURE DEVELOPMENT ACROSS
THE CENTRAL/SOUTHERN ROCKIES WITH AN INVERTED TROUGH AXIS EXTENDING
NORTHEAST ACROSS THE LOCAL AREA. DEEP LAYER MOISTURE WILL BE
INCREASING THURSDAY LEADING TO PRECIP CHANCES...ESPECIALLY LATER IN
THE DAY WITH LOW LEVEL MOIST ADVECTION ACTING ON THE SNOW PACK TO
LIKELY GENERATE FOG. THIS WILL PROBABLY KEEP TEMPS IN THE MID TO
UPPER 30S. PRECIP MAY END UP BEING MORE DRIZZLE THAN FALLING PRECIP
THROUGH THE DAY AND POSSIBLY THE EVENING/OVERNIGHT. THE UPPER FLOW
LOOKS TO REMAIN SPLIT WITH NORTHERN STREAM ENERGY KICKING THE
SURFACE LOW NORTHEAST RIGHT ACROSS THE AREA THURSDAY NIGHT AND
FRIDAY MORNING. THIS WILL ALSO BRING A COLD FRONT THOUGH THE AREA
EARLY FRIDAY. ANY RAIN WILL LIKELY TURN TO A MIX OR ALL SNOW FRIDAY
MORNING. OVERALL PRECIP AMOUNTS LOOK LIGHT WITH WEAK OR DISJOINTED
FORCING. HIGHS FRIDAY WILL LIKELY BE EARLY THEN FALL THROUGH THE
DAY.
SATURDAY THROUGH MONDAY...THIS PERIOD BEARS WATCHING AS ENERGY FROM
THE SOUTHERN STREAM CUTOFF UPPER LOW IS EXPECTED TO KICK NORTHEAST
THIS WEEKEND AS A REINFORCING UPPER TROUGH MOVES SOUTHEAST INTO THE
NORTHERN PLAINS. THIS WILL LIKELY SEND A SURFACE LOW AND/OR INVERTED
TROUGH NORTHEAST WITH RECENT GUIDANCE BRINGING IT SOUTHEAST OF THE
AREA. RIGHT NOW THE FAVORED TIME FOR THE SYSTEM TO BRING PRECIP TO
THE AREA WOULD BE LATER SATURDAY INTO SUNDAY. GIVEN THE PRECEDING
SHIFT IN THE UPPER FLOW TO A MORE ZONAL PATTERN AHEAD OF THE
TROUGHED FLOW...THERMAL FIELDS WILL BE MORE CRITICAL IN THAT THEY
WILL LIKELY BE WARM ENOUGH FOR A RANGE OF PRECIP TYPES TO OCCUR
DEPENDING ON WHERE THE LOW TRACKS. OVERALL SYSTEM STRENGTH AND
MOISTURE FEED SUPPORT HIGHER END PRECIP AMOUNTS WITH AFFECTED AREAS
DEPENDING ON THE TRACK. STILL VERY EARLY TO HAVE MUCH CONFIDENCE IN
DETAILS GIVEN THE EVOLUTION OF UPPER FLOW THAT NEEDS TO TAKE PLACE
IN THE MEANTIME BUT THERE LOOKS TO BE A GOOD CHANCE FOR A SYSTEM TO
BE AFFECTING THE REGION.
MDB
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 09Z...
* IFR CIGS WITH PERIODS OF MVFR VSBY ARE EXPECTED UNTIL THE SNOW
STARTS.
* SNOW RETURNS ARND 13Z WITH VSBY DROPPING TO AROUND A MILE. BRIEF
REDUCTIONS TO BELOW 1 SM PSBL.
* STRONG WEST WINDS SET UP LATE IN THE MORNING THROUGH THE
AFTN...20 KT GUSTING TO ARND 30 KT.
JEE
//DISCUSSION...UPDATED 06Z...
A LOW PRESSURE TROUGH IS OVER THE REGION WITH THE PARENT LOW OVER
SOUTH CENTRAL CANADA. ANOTHER UPPER LEVEL WAVE WILL APPROACH FROM
THE NW EARLY THIS MORNING KICKING OFF MORE SNOW. CIGS ARE
CURRENTLY MVFR WITH THE ONLY IFR SITES BEING RFD AND GYY. NOT SURE
HOW THE WIDESPREAD IFR CIGS WEST AND SOUTH OF THE TERMINALS ARE
STAYING OUT OF THE TERMINALS...BUT BETTING NO ONE IS COMPLAINING.
WHILE THE OBS ARE NOT SHOWING IFR...KEPT THE TEMPOS GOING WITH IFR
THROUGH THE MORNING. VSBYS HAVE ALSO COME UP WITH THE FOG
REMAINING ALSO TO THE SOUTH AND WEST OF THE TERMINALS. THIS IS
PROBABLY DUE TO THE SLIGHTLY DRIER AIR OVER THE TERMINALS.
WEST WINDS WILL PICK UP AS THE GRADIENT TIGHTENS...SO THINKING ALL
SITES OTHER THAN RFD SHOULD REMAIN VFR OVERNIGHT. THE SNOW ARRIVES
AROUND DAYBREAK AT RFD AND IT SHOULD BE ANOTHER QUICK SYSTEM.
FORCING LOOKS DECENT IN THE SNOW GROWTH ZONE...SO THINKING 1 1/2SM
IS STILL REASONABLE. MAY SEE A BRIEF PERIOD OF HEAVIER AND LESS
THAN 1 SM VSBY...BUT NOT ENTIRELY SURE WHERE IN THE SNOW WINDOW
THIS WOULD OCCUR. WILL LIKELY ADD A TEMPO FOR REDUCED VSBY LATER.
WINDS REALLY RAMP UP BY MID MORNING WITH GUSTS ARND 30 KT
EXPECTED. THE ADDED MIXING WILL HELP LIFT CIGS TO VFR WITH VFR
CONDITIONS EXPECTED FOR THE REST OF THE PERIOD. GUSTS DIMINISH IN
THE AFTN WITH WINDS BCMG SW BY WEDNESDAY MORNING.
JEE
//ORD AND MDW CONFIDENCE...UPDATED 09Z...
* MEDIUM-LOW CONFIDENCE IN HOW LONG CURRENT IFR CIGS AND MVFR VSBY
WILL PERSIST.
* HIGH CONFIDENCE IN SNOW OCCURRING.
* MEDIUM CONFIDENCE ON HOW LOW VSBY WILL GET WITH SNOW.
* HIGH CONFIDENCE IN ALL OTHER FORECAST ELEMENTS.
JEE
//OUTLOOK FOR ORD/MDW FOR 12Z WEDNESDAY-12Z MONDAY...UPDATED 00Z...
WEDNESDAY...VFR.
THURSDAY...CHANCE OF RAIN W/ FOG.
FRIDAY...CHANCE OF RAIN OR SNOW BECOMING ALL SNOW BY THE
AFTERNOON.
SATURDAY...CHANCE OF SNOW.
SUNDAY...CHANCE OF SNOW.
RODRIGUEZ
&&
.MARINE...
306 AM CST
FIRST OF ALL MADE NO CHANGES TO THE ONGOING HEADLINES AS THEY ALL
SEEM ON TRACK. A SMALL CRAFT ADVISORY WILL BE NEEDED FOR THE INDIANA
NEARSHORE WATERS AFTER THE GALE WARNING DUE TO LINGERING HAZARDOUS
WAVES.
LOW PRESSURE IS OVER ONTARIO AND IT WILL SLIDE TO THE EAST
TODAY...WHILE ITS COLD FRONT PASSES OVER THE LAKE THIS AFTERNOON.
AT THE SAME TIME HIGH PRESSURE BUILDS OVER THE CENTRAL PLAINS. THIS
WILL TIGHTEN THE PRESSURE GRADIENT OVER THE SOUTHERN END OF THE
LAKE...RESULTING IN LOW END GALES FORMING THIS MORNING THROUGH EARLY
THIS EVENING. WEST WINDS DIMINISH TO ARND 20 KT BY WEDNESDAY
MORNING AS HIGH PRESSURE PASSES TO THE SOUTH. WINDS PICK BACK UP ON
THE BACKSIDE OF THE HIGH LATE WEDNESDAY AFTERNOON INTO WEDNESDAY
EVENING. A BRIEF PERIOD OF SW GALES TO 35 KT IS POSSIBLE DURING
THAT TIME. A SMALL CRAFT ADVISORY WILL LIKELY BE NEEDED AS WELL FOR
WEDNESDAY AFTERNOON AND EVENING. WINDS WEAKEN WEDNESDAY NIGHT AS A
TROUGH OF LOW PRESSURE SITS OVER THE LAKE WEDNESDAY NIGHT THROUGH
THURSDAY. THE NEXT WEAK LOW MOVES OVER THE LAKE THURSDAY NIGHT
BEFORE SHIFTING EAST ON FRIDAY. WINDS TURN LIGHT AND VARIABLE
BEHIND THE LOW ON SATURDAY...BUT THEN TURN NORTH AND STRENGTHEN
SATURDAY NIGHT INTO SUNDAY IN RESPONSE TO THE NEXT SYSTEM. GUIDANCE
FEATURES ANOTHER LOW PUSHING UP THE OHIO RIVER VALLEY SATURDAY NIGHT
INTO SUNDAY WITH HIGH PRESSURE BUILDING DOWN THE PLAINS.
JEE
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...GALE WARNING...LMZ080-LMZ567-LMZ669-LMZ671-LMZ673-LMZ675-LMZ744-
LMZ745-LMZ777-LMZ779-LMZ868-LMZ870-LMZ872-LMZ874-LMZ876-
LMZ878...9 AM TUESDAY TO 9 PM TUESDAY.
SMALL CRAFT ADVISORY...LMZ740-LMZ741-LMZ742-LMZ743...9 AM
TUESDAY TO MIDNIGHT WEDNESDAY.
&&
$$
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AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
1154 PM CST MON DEC 16 2013
.DISCUSSION...
830 PM CST
CHARACTERISTIC OF THIS YOUNG 2013-2014 WINTER...ONE WEATHER ISSUE
DEPARTS AND ANOTHER QUICKLY FOLLOWS ON ITS HEELS. NOT ONLY IS THAT
NEXT ISSUE THE BRIEF SHOT OF SNOW TUESDAY MORNING...BUT ALSO
FREEZING FOG FOR AREAS ALONG AND SOUTH OF HIGHWAY 24 DURING THIS
EVENING. WE ISSUED A SPECIAL WEATHER STATEMENT FOR BOTH.
GOES WATER VAPOR SATELLITE AND UPPER AIR ANALYSES INDICATE THE
SHORT WAVE OF THE EARLIER SNOW IS HEADING EAST OVER LAKE MI ON A
STRONG 80 KT 500MB JET MAX. THE MAIN PRESSURE FALLS ARE LOCATED
EVEN FURTHER NORTH ACROSS THE FAR NORTHERN GREAT LAKES...SO THE
SURFACE REFLECTION ACROSS OUR AREA HAS BEEN WEAK. THIS HAS HELPED
ALLOW FOR SATURATION IN THE LOW-LEVELS AND THE INABILITY TO ADVECT
IT AWAY. BOTH THE 00Z DVN AND ILX SOUNDINGS SHOWED STRONG
INVERSIONS OF AROUND 7C WITH NEARLY COMPLETE SATURATION BELOW.
SATELLITE AND OBSERVATIONS CORRELATE WITH THIS LOW-LEVEL MOISTURE
WELL...DEPICTING LOW VISIBILITIES ACROSS CENTRAL IL.
LAW ENFORCEMENT HAS REPORTED THIS ALONG WITH ICY ROADS IN FORD AND
BENTON COUNTIES AS TEMPERATURES ARE WELL BELOW FREEZING. ITS NOT
IMPOSSIBLE THERE IS A LITTLE DRIZZLE IN THIS MUCK AS WELL GIVEN
THE DECENT WIND FLOW AND SLIGHT ASCENT AT AND JUST ABOVE THE
INVERSION LEVEL. EVENTUALLY WESTERLY SURFACE WINDS DO INCREASE
SOME AS THE PRESSURE GRADIENT TIGHTENS OVERNIGHT. RAP AND HRRR
VISIBILITY AND CIG FORECAST DO TRY TO SHOW THE VERY LOW SATURATION
ADVECTING EAST BY EARLY OVERNIGHT AND THAT SEEMS
REASONABLE...THOUGH THEY COULD BE A LITTLE HASTY WITH THAT. GIVEN
THE SOMEWHAT LIMITED EXPECTED DURATION AND REPORTS OF VISIBILITY
NOT BEING AS LOW AS ONE QUARTER MILE IN OUR FORECAST AREA...HAVE
JUST GONE WITH AN SPS AS OPPOSED TO AN ADVISORY.
NEXT QUICK MOVING CLIPPER IS SEEN IN NW MN ON WATER VAPOR AND IS
ON A PATH FOR THE CWA BY DAYBREAK. THE GOING TIMING IN THE GRIDS
LOOKS GREAT COMPARED TO SHORT TERM/HIGH RES GUIDANCE WHICH SEEMED
TO HAVE HANDLED TODAYS SIMILAR EVENT WELL. RATIOS LOOK HIGHER WITH
THE TUE MORNING EVENT THAN TODAY...AND THE LATEST LOCAL 8KM ARW
DOES SHOW A COUPLE HOURS OF NEAR 25:1 RATIOS WHICH MAY BE A BIT
HIGH...BUT DO AT LEAST INDICATE THAT BURST POTENTIAL DURING RUSH
HOUR. TIMING AND MAGNITUDE OF WIND GUST INCREASE STILL LOOKS
REPRESENTATIVE AND THE FORECAST SPEEDS SHOULD BE ENOUGH TO
REALIZE PATCHY BLOWING OF THE FRESH SNOWFALL IN OPEN AREAS.
MTF
//PREV DISCUSSION...
305 PM CST
NUMEROUS FORECAST CONCERNS GOING THROUGH THE WEEKEND AS THE UPPER
FLOW PATTERN SHIFTS FROM FAVORING NORTHWEST FLOW AND PERIODIC
CLIPPERS TO A SOUTHWESTERLY FLOW SUPPORTING A BRIEF WARM UP FOLLOWED
BY THE POTENTIAL FOR STRONGER SOUTHWEST SYSTEMS.
EARLY AFTERNOON WATER VAPOR IMAGERY SHOWS A BROAD TROUGH OVER MOST
OF THE U.S. WITH BROAD RIDGING COMING OVER THE WEST COAST OF NORTH
AMERICA. EMBEDDED IN THE BROAD TROUGH ARE A SERIES OF WAVES...THE
FIRST OF WHICH IS ENTERING THE LOCAL AREA BRINGING BANDS OF SNOW.
THE NEXT WAVE OF NOTE IS MORE SUBTLE AS IT MOVES SOUTHEAST ACROSS
THE CENTRAL ALBERTA/SASKATCHEWAN BORDER AND GENERATES SNOW INTO
NORTHEASTERN MONTANA. THIS WAVE WILL MOVE INTO THE LOCAL AREA
TOMORROW MORNING. OTHERWISE...THE PATTERN WILL BECOME LESS AMPLIFIED
DURING MID WEEK AS THE MAIN UPPER TROUGH PUSHES EAST FOLLOWED BY THE
BROAD RIDGING CURRENTLY TO THE WEST.
TONIGHT AND TUESDAY...THE CURRENT CLIPPER WILL BE DEPARTING THE AREA
THROUGH THE EARLY EVENING HOURS BRINGING SNOW TO AN END AND TURNING
WINDS WESTERLY. ATTENTION TURNS TO THE MORE SUBTLE WAVE MOVING
SOUTHEAST ACROSS THE CENTRAL ALBERTA/SASKATCHEWAN BORDER AND A
SURFACE LOW TO THE EAST OF THE WAVE OVER MANITOBA WHICH WILL ALSO
MOVE SOUTHEAST WITH THE CENTER TRACKING INTO WESTERN ONTARIO TUESDAY
MORNING. A COLD FRONT WILL TRAIL THE LOW AND PUSH ACROSS THE LOCAL
AREA DURING THE MORNING. ANOTHER ROUND OF SNOW WILL LIKELY ACCOMPANY
THE PASSAGE OF THE UPPER WAVE AND SURFACE COLD FRONT. GUIDANCE
CONTINUES TO SHOW A RANGE OF SOLUTIONS WITH THE EXTENT/AMOUNT OF THE
PRECIP ACROSS THE AREA BUT GENERALLY HAS BEEN MORE BULLISH WITH
SNOWFALL COVERAGE OVER THE AREA THAN EARLIER RUNS. THIS FALLS IN
LINE WITH THE OBSERVED TRENDS OF THE CLIPPER LAST NIGHT AND THE ONE
CURRENTLY CROSSING THE AREA AND SEE LITTLE TO SUPPORT HAVING
DIFFERENT EXPECTATIONS FOR THIS NEXT ONE. WILL CONTINUE WITH THE
HIGH POPS ACROSS THE NORTHERN QUARTER TO THIRD OF THE AREA...WITH
THE FOCUS FOR MOST INTENSE AND LONGEST DURATION OF SNOW ALONG AND
NORTH OF A ROCKFORD TO CHICAGO TO VALPARAISO LINE...WHILE LIGHTER
SNOW FALLS TO THE SOUTH OF THIS LINE. THE UPPER WAVE LOOKS TO BE
SLIGHTLY WEAKER THAN THE ONE CURRENTLY CROSSING THE AREA BUT DOES
LOOK TO STRENGTHEN A BIT AS IT APPROACHES IN CONJUNCTION WITH A
BETTER ALIGNMENT OF THE LEFT EXIT OF AN UPPER JET. MODEL GUIDANCE
SHOWS A RANGE OF SNOWFALL AMOUNTS FROM VERY LITTLE TO A FEW INCHES
AND EVEN DIFFERS IN THE MAGNITUDE OF FORCING RELATIVE TO THE FAVORED
CRYSTAL GROWTH REGION. AT THIS POINT FEEL THE BEST ROUTE IS TO STICK
WITH THE OBSERVED TRENDS OF RECENT CLIPPERS AND ACCOUNT FOR THE
EXPECTATION OF SOME BETTER ORGANIZATION OF THE UPPER WAVE AND
FAVORED JET PLACEMENT. WITH THIS IN MIND FEEL THAT IT IS LIKELY THAT
NORTHERN PORTIONS OF THE AREA WILL SEE ANOTHER 1 TO POSSIBLY 2 INCH
EVENT WITH HIGH SNOW RATIOS. STEEP MID LEVEL LAPSE RATES AND GOOD
FORCING IN THE SNOW GROWTH ZONE SIMILAR TO TODAY SUPPORT
ACCUMULATION RATES OF 0.5 TO 0.75 IN/HR. CONTINUED WITH A SNOW RATIO
OF 16-18:1 OVERALL. MAY BE ABLE TO USE AMOUNTS/RATIOS/RATES FROM THE
CURRENT SNOW TO BETTER REFINE FOR THE MORNING. TIMING-WISE...SNOW
SHOULD MOVE INTO THE NORTHWEST PART OF THE AREA TOWARD DAYBREAK AND
THE CHICAGO METRO RIGHT AROUND OR JUST AFTER DAYBREAK THEN EXIT TO
THE EAST DURING THE LATE MORNING HOURS. THE PASSAGE OF THE COLD
FRONT WILL BRING A SHIFT TO NORTHWEST WINDS WHICH WILL INCREASE WITH
GUSTS PUSHING 35-40 MPH FROM LATE MORNING THROUGH THE AFTERNOON
LEADING TO BLOWING SNOW. HIGHS SHOULD BE RIGHT AROUND 30...THOUGH
THERE COULD BE A SLIGHT DECREASE IN TEMPS IN THE AFTERNOON WITH SOME
COOL ADVECTION BUT CLEARING SKIES AND SUNSHINE MAY OFFSET THIS. LOWS
TUESDAY NIGHT SHOULD FALL INTO THE MID TEENS WITH WINDS DIMINISHING
AND TURNING SOUTHWEST.
WEDNESDAY THROUGH FRIDAY...THE UPPER TROUGH CARVED OUT BY THE SERIES
OF CLIPPERS WILL SWING TO THE EAST AND OFF THE NEW ENGLAND COAST
WEDNESDAY ALLOWING FOR BROAD UPPER RIDGING TO SPREAD ACROSS THE
U.S. THIS WILL BRING A PUSH OF MID LEVEL WARM ADVECTION TO THE
REGION WEDNESDAY INTO THURSDAY WITH H85 TEMPS WARMING TO AROUND +6C
OR SO AND H92 TEMPS WARMING JUST ABOVE 0C. THIS WILL ALLOW FOR
SURFACE WARMING AS WELL BUT SNOW COVER WILL BE ONE LIMITING FACTOR.
TEMPS WEDNESDAY WILL BE TRICKY BECAUSE ASIDE FROM SOME MID LEVEL WAA
CLOUDS EARLY THERE WILL LIKELY BE AT LEAST SOME SUN AS WELL AS A
STRONG SOUTHWEST WIND. BOTH OF THESE POINT TOWARD WARMER HIGHS GIVEN
THAT THE LOWER ATMOSPHERE WILL STILL BE RELATIVELY DRY. THIS SHOULD
ALLOW MOST AREAS TO WARM TO OR JUST ABOVE FREEZING. BY THURSDAY...AN
UPPER TROUGH WILL BE WORKING INTO THE WESTERN U.S. WITH THE UPPER
FLOW SPLITTING INTO TWO STREAMS AS THE TROUGH DIGS SOUTH AND CUTS
OFF OVER OR JUST OFF THE CALIFORNIA COAST. HEIGHT FALLS AHEAD OF
THIS TROUGHING WILL LEAD TO SURFACE LOW PRESSURE DEVELOPMENT ACROSS
THE CENTRAL/SOUTHERN ROCKIES WITH AN INVERTED TROUGH AXIS EXTENDING
NORTHEAST ACROSS THE LOCAL AREA. DEEP LAYER MOISTURE WILL BE
INCREASING THURSDAY LEADING TO PRECIP CHANCES...ESPECIALLY LATER IN
THE DAY WITH LOW LEVEL MOIST ADVECTION ACTING ON THE SNOW PACK TO
LIKELY GENERATE FOG. THIS WILL PROBABLY KEEP TEMPS IN THE MID TO
UPPER 30S. PRECIP MAY END UP BEING MORE DRIZZLE THAN FALLING PRECIP
THROUGH THE DAY AND POSSIBLY THE EVENING/OVERNIGHT. THE UPPER FLOW
LOOKS TO REMAIN SPLIT WITH NORTHERN STREAM ENERGY KICKING THE
SURFACE LOW NORTHEAST RIGHT ACROSS THE AREA THURSDAY NIGHT AND
FRIDAY MORNING. THIS WILL ALSO BRING A COLD FRONT THOUGH THE AREA
EARLY FRIDAY. ANY RAIN WILL LIKELY TURN TO A MIX OR ALL SNOW FRIDAY
MORNING. OVERALL PRECIP AMOUNTS LOOK LIGHT WITH WEAK OR DISJOINTED
FORCING. HIGHS FRIDAY WILL LIKELY BE EARLY THEN FALL THROUGH THE
DAY.
SATURDAY THROUGH MONDAY...THIS PERIOD BEARS WATCHING AS ENERGY FROM
THE SOUTHERN STREAM CUTOFF UPPER LOW IS EXPECTED TO KICK NORTHEAST
THIS WEEKEND AS A REINFORCING UPPER TROUGH MOVES SOUTHEAST INTO THE
NORTHERN PLAINS. THIS WILL LIKELY SEND A SURFACE LOW AND/OR INVERTED
TROUGH NORTHEAST WITH RECENT GUIDANCE BRINGING IT SOUTHEAST OF THE
AREA. RIGHT NOW THE FAVORED TIME FOR THE SYSTEM TO BRING PRECIP TO
THE AREA WOULD BE LATER SATURDAY INTO SUNDAY. GIVEN THE PRECEDING
SHIFT IN THE UPPER FLOW TO A MORE ZONAL PATTERN AHEAD OF THE
TROUGHED FLOW...THERMAL FIELDS WILL BE MORE CRITICAL IN THAT THEY
WILL LIKELY BE WARM ENOUGH FOR A RANGE OF PRECIP TYPES TO OCCUR
DEPENDING ON WHERE THE LOW TRACKS. OVERALL SYSTEM STRENGTH AND
MOISTURE FEED SUPPORT HIGHER END PRECIP AMOUNTS WITH AFFECTED AREAS
DEPENDING ON THE TRACK. STILL VERY EARLY TO HAVE MUCH CONFIDENCE IN
DETAILS GIVEN THE EVOLUTION OF UPPER FLOW THAT NEEDS TO TAKE PLACE
IN THE MEANTIME BUT THERE LOOKS TO BE A GOOD CHANCE FOR A SYSTEM TO
BE AFFECTING THE REGION.
MDB
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 06Z...
* MVFR CIGS WITH PERIODS OF IFR PSBL OVERNIGHT. MVFR PERSISTS
THROUGH THE MORNING.
* SNOW RETURNS ARND 12Z WITH VSBY DROPPING TO AROUND A MILE. BRIEF
REDUCTIONS TO BELOW 1 SM PSBL.
* STRONG WEST WINDS SET UP LATE IN THE MORNING THROUGH THE
AFTN...20 KT GUSTING TO ARND 30 KT.
JEE
//DISCUSSION...UPDATED 06Z...
A LOW PRESSURE TROUGH IS OVER THE REGION WITH THE PARENT LOW OVER
SOUTH CENTRAL CANADA. ANOTHER UPPER LEVEL WAVE WILL APPROACH FROM
THE NW EARLY THIS MORNING KICKING OFF MORE SNOW. CIGS ARE
CURRENTLY MVFR WITH THE ONLY IFR SITES BEING RFD AND GYY. NOT SURE
HOW THE WIDESPREAD IFR CIGS WEST AND SOUTH OF THE TERMINALS ARE
STAYING OUT OF THE TERMINALS...BUT BETTING NO ONE IS COMPLAINING.
WHILE THE OBS ARE NOT SHOWING IFR...KEPT THE TEMPOS GOING WITH IFR
THROUGH THE MORNING. VSBYS HAVE ALSO COME UP WITH THE FOG
REMAINING ALSO TO THE SOUTH AND WEST OF THE TERMINALS. THIS IS
PROBABLY DUE TO THE SLIGHTLY DRIER AIR OVER THE TERMINALS.
WEST WINDS WILL PICK UP AS THE GRADIENT TIGHTENS...SO THINKING ALL
SITES OTHER THAN RFD SHOULD REMAIN VFR OVERNIGHT. THE SNOW ARRIVES
AROUND DAYBREAK AT RFD AND IT SHOULD BE ANOTHER QUICK SYSTEM.
FORCING LOOKS DECENT IN THE SNOW GROWTH ZONE...SO THINKING 1 1/2SM
IS STILL REASONABLE. MAY SEE A BRIEF PERIOD OF HEAVIER AND LESS
THAN 1 SM VSBY...BUT NOT ENTIRELY SURE WHERE IN THE SNOW WINDOW
THIS WOULD OCCUR. WILL LIKELY ADD A TEMPO FOR REDUCED VSBY LATER.
WINDS REALLY RAMP UP BY MID MORNING WITH GUSTS ARND 30 KT
EXPECTED. THE ADDED MIXING WILL HELP LIFT CIGS TO VFR WITH VFR
CONDITIONS EXPECTED FOR THE REST OF THE PERIOD. GUSTS DIMINISH IN
THE AFTN WITH WINDS BCMG SW BY WEDNESDAY MORNING.
JEE
//ORD AND MDW CONFIDENCE...UPDATED 06Z...
* HIGH CONFIDENCE IN CIG TRENDS...LOW CONFIDENCE OF IFR CIGS
RETURNING OVERNIGHT.
* HIGH CONFIDENCE IN SNOW TOMORROW.
* MEDIUM CONFIDENCE IN VSBY FALLING TO BELOW 1SM IN SNOW...BUT
LOW CONFIDENCE IN THE TIME WINDOW.
* HIGH CONFIDENCE IN ALL OTHER FORECAST ELEMENTS.
JEE
//OUTLOOK FOR ORD/MDW FOR 12Z WEDNESDAY-12Z MONDAY...UPDATED 00Z...
WEDNESDAY...VFR.
THURSDAY...CHANCE OF RAIN W/ FOG.
FRIDAY...CHANCE OF RAIN OR SNOW BECOMING ALL SNOW BY THE
AFTERNOON.
SATURDAY...CHANCE OF SNOW.
SUNDAY...CHANCE OF SNOW.
RODRIGUEZ
&&
.MARINE...
204 PM CST
A SERIES OF DISTURBANCES WILL LEAD TO SEVERAL WIND SHIFTS THROUGH
THE REMAINDER OF THE WEEK...AS WELL AS A BRIEF PERIOD OF GALES WHICH
IS EXPECTED TUESDAY. TODAY HIGH PRESSURE IS STARTING TO DRIFT EAST
OF LAKE MICHIGAN WITH SOUTHWEST FLOW INCREASING IN ADVANCE OF AN
APPROACHING COLD FRONT. THIS FIRST FRONT WILL MOVE ACROSS LAKE
MICHIGAN WITH WINDS VEERING TO WESTERLY OVERNIGHT. A SECOND FRONT
WILL BE RIGHT ON ITS HEELS THOUGH...AND WILL PUSH ACROSS LAKE
MICHIGAN TUESDAY AFTERNOON WITH WINDS SHIFTING NORTHWESTERLY. A
BETTER SURGE OF COLD AIR WILL BE ASSOCIATED WITH THIS SECOND
FRONT...AS WELL AS A TIGHTER PRESSURE GRADIENT WITH A MODERATE RIDGE
BUILDING ALONG THE MISSISSIPPI VALLEY...LEADING TO A PERIOD OF WEST
TO NORTHWEST GALES...PARTICULARLY ACROSS THE SOUTH HALF OF THE LAKE.
GALES WILL DIMINISH TUESDAY NIGHT AND WINDS WILL BEGIN TO BACK TO
THE SOUTHWEST WEDNESDAY AS THE RIDGE PROGRESSES EAST ACROSS LAKE
MICHIGAN. SOUTHWEST WINDS FRESHEN UP AGAIN WEDNESDAY NIGHT AS YET
ANOTHER FRONT IS POISED TO SWEEP ACROSS THE LAKE EARLY THURSDAY.
MODERATE NORTHERLY FLOW IS EXPECTED FRIDAY BEHIND THE FRONT AS
ANOTHER LOW PRESSURE SKIRTS TO THE EAST...JUST SOUTH OF THE
GREAT LAKES.
BMD
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...GALE WARNING...LMZ080-LMZ567-LMZ669-LMZ671-LMZ673-LMZ675-LMZ744-
LMZ745-LMZ777-LMZ779-LMZ868-LMZ870-LMZ872-LMZ874-LMZ876-
LMZ878...9 AM TUESDAY TO 9 PM TUESDAY.
SMALL CRAFT ADVISORY...LMZ740-LMZ741-LMZ742-LMZ743...9 AM
TUESDAY TO MIDNIGHT WEDNESDAY.
&&
$$
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AREA FORECAST DISCUSSION
NWS QUAD CITIES IA IL
1147 PM CST MON DEC 16 2013
.SHORT TERM...(THIS EVENING THROUGH TUESDAY)
ISSUED AT 302 PM CST MON DEC 16 2013
MAIN SHORT TERM CONCERN IS ON SNOW POTENTIAL LATE TONIGHT INTO
TUESDAY MORNING.
CURRENTLY AS OF 21Z...WATER VAPOR LOOP AND RAP 500MB HEIGHT ANALYSIS
SHOWED RIDGING OVER THE WESTERN U.S. INTO BRITISH COLUMBIA WHILE
TROUGHING DOMINATED EASTERN CANADA AND IN GENERAL THE EASTERN U.S..
WITHIN THIS TROUGHING...TWO SHORTWAVES WERE NOTED OVER SOUTHERN
MINNESOTA AND IN NORTH DAKOTA. THE SHORTWAVE OVER SOUTHERN MINNESOTA
WAS PRODUCING A BAND OF SNOW ON RADAR MARCHING ACROSS WISCONSIN...
CLIPPING PORTIONS OF NORTHEAST IOWA INTO NORTHERN ILLINOIS. THE
NEXT AREA OF SNOW EXISTS OVER EASTERN MONTANA INTO WESTERN NORTH
DAKOTA...ON THE WEST SIDE OF THE SHORTWAVE THERE. THIS BAND OF
SNOW IS BEING PRODUCED MORE BY MID-LEVEL FRONTOGENESIS AND UPPER
DIVERGENCE IN THE RIGHT ENTRANCE REGION OF A 110-130 KT JET STREAK
IN NORTHEAST MONTANA PER RAP ANALYSIS. CLOSER TO THE FORECAST
AREA...COMBINATION OF LOW SUN ANGLE AND A SURFACE RIDGE OF HIGH
PRESSURE IN PLACE HAS BEEN LIMITING MIXING...KEEPING A STRATUS
DECK IN PLACE FOR MUCH OF THE DAY. THE AIRMASS IS ALSO COOL IN A
SHALLOW LAYER...SINCE 850MB TEMPS RANGE FROM 4C TO -4C SOUTHWEST
TO NORTHEAST ACROSS THE FORECAST AREA. 12Z DVN SOUNDING REALLY
REFLECTS THE SHALLOW COOL LAYER AND THE STRATUS WITH A SATURATED
VERY STRONG INVERSION BETWEEN 925MB AND 825MB.
FOCUS IS ON THE SHORTWAVE COMING OUT OF NORTH DAKOTA...ALONG WITH
THE MID LEVEL FRONTOGENESIS AND UPPER JET STREAK ON ITS WESTERN
SIDE...WHICH ARE PROGGED TO DIG SOUTHEAST TO DUBUQUE BY 12Z TUESDAY.
MODELS ARE IN VERY GOOD AGREEMENT ON ALL OF THE AFOREMENTIONED
FEATURES THUS HAVE FOLLOWED THE CONSENSUS. WE SHOULD SEE A DRY
EVENING AREA WIDE...THEN THE BAND OF SNOW UP IN WESTERN NORTH DAKOTA
WILL ARRIVE GENERALLY TO LOCATIONS ALONG/NORTH OF US-20. RAISED
PRECIPITATION CHANCES UP TO 70 IN THIS AREA...AND EVEN INCLUDED SOME
CHANCES A BIT FARTHER SOUTH TOWARDS BUT NOT TO THE I-80 CORRIDOR IN
THE EVENT THE BAND SLIPS A BIT FARTHER SOUTH. MUCH OF THE SNOW LOOKS
TO BE CONFINED BETWEEN 06-12Z TUESDAY...WITH PERHAPS A LITTLE SNOW
LINGERING IN NORTHWEST ILLINOIS BETWEEN 12-14Z BEFORE IT PUSHES
OFF TO THE EAST. TOTAL SNOW AMOUNTS MAY BE UPWARDS OF 1/2 INCH TO
1 INCH...HIGHEST NEAR DUBUQUE.
OTHER ISSUES OF NOTE IN THE SHORT TERM.
1. WINDS PICKING UP IN THE WAKE OF THE SHORTWAVE PASSAGE. THE
PRESSURE GRADIENT IS PROGGED TO REALLY TIGHTEN UP TUESDAY
MORNING...RESULTING IN WEST TO NORTHWEST SPEEDS OF 15 TO 25 MPH WITH
GUSTS PERHAPS APPROACHING 35 MPH. WINDS DO NOT LOOK TO RELAX UNTIL
LATE IN THE DAY WITH DIURNAL COOLING AND THE APPROACH OF A SURFACE
RIDGE AXIS. THE WINDS COULD BLOW SOME OF THE SNOW AROUND THAT FALLS
TONIGHT INTO TUESDAY MORNING.
2. CLOUDS. THE STRATUS DECK CURRENTLY IN PLACE LOOKS TO CLEAR OUT
THIS EVENING AS WINDS SHIFT WEST...DRAWING DRIER AIR IN OUT OF
NEBRASKA AND WESTERN IOWA. SKIES HAVE BEEN CLEARING IN WESTERN IOWA
ALL DAY REFLECTING THE DRY AIR. CLOUDS SHOULD TEMPORARILY INCREASE
WITH THE APPROACH OF THE NORTH DAKOTA SNOW BAND...THEN DECREASE
AGAIN ON TUESDAY IN ITS WAKE.
3. TEMPERATURES. IF WINDS CAN DECOUPLE THIS EVENING WHEN SKIES ARE
CLEAR...READINGS COULD DIP INTO THE SINGLE DIGITS. CONFIDENCE IS NOT
HIGH ENOUGH TO GO THAT COLD...THUS STAYED CLOSER TOWARDS THE
CONSENSUS. HIGHS DEFINITELY WARMER TOMORROW WITH MORE SUN AND WINDS
FOR MIXING...THOUGH 850MB TEMPS ARE COOLER BETWEEN -8 AND -10C.
.LONG TERM...(TUESDAY NIGHT THROUGH MONDAY)
ISSUED AT 302 PM CST MON DEC 16 2013
MAIN LONG TERM FORECAST CONCERNS ARE ON PRECIPITATION TYPES
WEDNESDAY NIGHT THROUGH FRIDAY...AND AGAIN SATURDAY INTO SUNDAY.
MODELS REMAIN CONSISTENT IN SHOWING A MAJOR PATTERN CHANGE OVER THE
NEXT FEW DAYS...RESULTING FROM A POTENT TROUGH DIGGING DOWN FROM
NORTHERN BRITISH COLUMBIA AT 00Z WEDNESDAY TO SOUTHERN CALIFORNIA BY
00Z FRIDAY. THIS MODULATES THE PATTERN DOWNSTREAM OVER THE
FORECAST AREA FROM NORTHWEST FLOW ON TUESDAY...TO ZONAL ON
WEDNESDAY...AND FINALLY SOUTHWESTERLY ON THURSDAY. IN RESPONSE TO
THIS PATTERN CHANGE...WARM ADVECTION IS EXPECTED...WITH MOISTURE
ADVECTION COMING INTO PLAY AS WELL ONCE HIGH PRESSURE MOVES OUT OF
THE WAY OF THE GULF OF MEXICO COME WEDNESDAY.
AFTER WHAT WILL BE QUIET WEATHER TUESDAY NIGHT AND WEDNESDAY...
THINGS GET MORE INTERESTING FOR WEDNESDAY NIGHT AND THURSDAY. 16.12Z
NAM/GFS/ECMWF ALL SHOW LOW LEVEL SATURATION TAKING PLACE WEDNESDAY
NIGHT...WITH THE DEPTH OF THE SATURATION GROWING IN TIME THROUGH
THURSDAY. AS HIGHER MOISTURE IMPINGES ON THE COOLER...SNOW PACK OVER
THE AREA...ANTICIPATING AREAS OF FOG TO DEVELOP WEDNESDAY EVENING.
MAY EVENTUALLY NEED A DENSE FOG ADVISORY. IN ADDITION...THERE COULD
EVEN BE SOME DRIZZLE IN THIS FOG WEDNESDAY NIGHT...AS SUGGESTED BY
THE 16.12Z NAM QPF FIELDS...BUT CONFIDENCE IS TOO LOW TO MENTION
PRIOR TO 12Z THURSDAY. BETTER MODEL AGREEMENT AFTER 12Z THURSDAY FOR
DEEPER LOW LEVEL MOISTURE AND THE ISENTROPIC LIFT DOES GRADUALLY
INCREASE. THUS...PRECIPITATION CHANCES INCREASE THROUGH THE DAY
THURSDAY. SOUNDINGS DEPICT NO ICE IN THE CLOUDS...THUS ANY
PRECIPITATION THAT FALLS WILL BE IN LIQUID FORM...WITH THE SURFACE
AND POSSIBLY EVEN GROUND TEMPERATURE DICTATING WHETHER IT FREEZES
ON CONTACT. IT DOES SEEM THAT THE GREATER ICING THREAT WOULD BE
NORTH OF I-80 THURSDAY MORNING...SINCE TEMPERATURES IN MOST PLACES
ALONG/SOUTH OF I-80 MAY STRUGGLE TO FALL BELOW FREEZING WEDNESDAY
NIGHT. A COLD FRONTAL BOUNDARY IS PROGGED TO SLOWLY SLIDE
SOUTHEAST THROUGH THE FORECAST AREA ON THURSDAY...WHICH COMBINED
WITH DAYTIME HEATING SHOULD HELP TO GET RID OF THE FOG.
AS WE HEAD TOWARDS THE WEEKEND...MODELS ARE IN GOOD AGREEMENT
SPLITTING UP THAT WESTERN TROUGH. THE NORTHERN PORTION SHORTWAVE
TROUGH IS PROGGED TO SLIDE ACROSS MN AND WI...WHICH SIMULTANEOUSLYBRINGS
A SURFACE LOW NORTHEAST THROUGH THE FORECAST AREA. PRECIPITATION
SHOULD INTENSIFY SOME AHEAD OF THE SURFACE LOW...ENOUGH TO WARRANT
HIGHER PRECIPITATION CHANCES. THE PRECIPITATION THEN EXITS OFF TO
THE EAST FRIDAY WITH THE PASSAGE OF THE TROUGH. AGAIN...NO ICE IS
SUGGESTED IN THE CLOUDS...MEANING EITHER RAIN OR FREEZING RAIN AT
THE SURFACE DEPENDING ON THE SURFACE TEMPERATURE.
FOCUS THEN SHIFTS TO THE SOUTHERN PORTION OF THE WESTERN
TROUGH...WHICH THE 16.12Z ECMWF/CANADIAN/GFS ALL SHOW LIFTING UP
THROUGH THE CENTRAL PLAINS AND ILLINOIS SATURDAY INTO SUNDAY. WE
NEED TO WATCH THIS SHORTWAVE AND ASSOCIATED SYSTEM CLOSELY FOR
SNOW...SLEET AND FREEZING RAIN. THE THREAT FOR SLEET AND FREEZING
RAIN RIGHT NOW SEEMS TO BE HIGHEST SOUTHEAST OF A LINE FROM ROCK
FALLS TO MOLINE IL AND MT. PLEASANT IA. RAISED PRECIPITATION
CHANCES IN THIS AREA TOO FOR SATURDAY NIGHT TOWARDS 60 AS MODELS
ARE COMING INTO BETTER AGREEMENT. COLDER AND DRIER AIR WILL FILTER
IN BEHIND THIS SYSTEM FOR SUNDAY NIGHT AND MONDAY AS AN ARCTIC
HIGH PRESSURE AREA BUILDS SOUTH INTO THE REGION.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z TUESDAY NIGHT)
ISSUED AT 1125 PM CST MON DEC 16 2013
BACK EDGE OF LOW CLOUDS WITH IFR TO LIFR CIGS AND LIGHT FOG HAS
MOVED EAST OF KCID TERMINAL AND EXPECTED TO CONTINUE SLOW AND
STEADY EASTWARD MOVEMENT OVERNIGHT EXITING REST OF THE TERMINALS.
SOME CONCERNS WITH RECENT SATELLITE AND OB TRENDS DEPICTING LOW
CLOUDS SLOWING OVER FAR NORTHEAST IOWA AHEAD OF SURFACE TROUGH.
THIS WILL NEED TO BE WATCHED FOR POSSIBILITY OF LOW CLOUDS
WITH IFR/MVFR CIGS MOVING BACK INTO TERMINALS ESPECIALLY KCID AND
KDBQ EARLY TUESDAY MORNING AS FLOW TURNS MORE NORTHWESTERLY.
AN UPPER LEVEL DISTURBANCE OVER THE DAKOTAS WILL PASS THROUGH THE
AREA TUESDAY MORNING AND MAY SEE SOME SNOW SHOWERS SWEEP THROUGH
THE AREA WITH THIS FEATURE. POTENTIAL TO SEE BRIEF PERIODS OF
VSBYS AROUND 1 MILE WITH QUICK ACCUMS OF A FEW TENTSH OF AN INCH
AND CIGS 1-2KFT AGL WITH BURST OF SNOW IN THE SHOWERS. COVERAGE
AND IMPACT TO TERMINALS UNCERTAIN THUS LIMITED MENTION TO JUST VCSH
AT ALL SITES FOR NOW DURING THE MORNING. COLD ADVECTION AND
TIGHTENING PRESSURE GRADIENT TO RESULT IN PERIOD OF GUSTY NORTHWEST
WINDS 15-30 KTS. HIGH PRESSURE BUILDS IN BY TUESDAY EVENING WITH
VFR CONDITIONS AND NORTHWEST WINDS 10-15 KTS.
&&
.DVN WATCHES/WARNINGS/ADVISORIES...
IA...NONE.
IL...NONE.
MO...NONE.
&&
$$
SHORT TERM...AJ
LONG TERM...AJ
AVIATION...05
AREA FORECAST DISCUSSION
NWS GOODLAND KS
756 PM MST WED DEC 18 2013
.UPDATE...
ISSUED AT 748 PM MST WED DEC 18 2013
SEEING A LOT OF VARIABILITY WITH HOURLY TEMPERATURES TONIGHT WITH
A FEW SITES ALREADY DROPPING TO AROUND FREEZING...BUT THEN RISING
AGAIN AS HIGH CLOUDS MOVE OVER. TRIED TO ACCOUNT FOR THIS
VARIABILITY...BUT GIVEN THE DEGREE OF CHANGE GETTING A PERFECT
CURVE WILL BE DIFFICULT. DESPITE THE INITIAL DROP...CURRENT
FORECAST LOOKS ON TRACK WITH ONLY A FEW MINOR CHANGES MADE. LOOKS
LIKE FRONT WILL BEGIN TO IMPACT AREA IN THE MORNING BUT STRONGEST
PUSH OF COLD AIR WILL OCCUR JUST AFTER 18Z.
&&
.SHORT TERM...(THIS AFTERNOON THROUGH THURSDAY)
ISSUED AT 100 PM MST WED DEC 18 2013
LATEST WV IMAGERY AND RAP H5 ANALYSIS INDICATES WESTERLY ZONAL FLOW
IN PLACE ACROSS THE UNITED STATES...WITH TWO SHORTWAVE TROUGHS
UPSTREAM OFF THE WEST COAST. THE FIRST TROUGH IS CENTERED OVER
BRITISH COLUMBIA...WITH THE SECOND JUST WEST OF THE BAJA PENINSULA.
AT THE SURFACE A TROUGH OF LOW PRESSURE EXTENDS FROM EASTERN
COLORADO AND ACROSS SOUTH WEST NEBRASKA. A COLD FRONT IS IN PLACE
ACROSS CENTRAL MONTANA AND NORTH DAKOTA WITH AN ARCTIC HIGH PRESSURE
SYSTEM LURKING TO THE NORTH OF THE FEATURE READY TO MAKE A TREK
SOUTH INTO THE PLAINS.
WITH WESTERLY CROSS MOUNTAIN FLOW AND EMBEDDED UPPER LEVEL ENERGY
CONTINUE TO MOVE EAST I WOULD EXPECT CLOUD COVER TO BEGIN TO
INCREASE ONCE AGAIN TONIGHT...ESPECIALLY AFTER MIDNIGHT AS A TROUGH
BEGINS TO MOVE FROM THE PAC NW AND DEEPEN ACROSS THE GREAT BASIN.
CLOUD COVER COULD HAVE A NEGATIVE IMPACT ON RADIATIONAL COOLING...AND
I WAS NOT CONFIDENT IN HOW LOW WE WILL ACTUALLY DROP BEFORE WINDS
POSSIBLY INCREASE TOWARDS DAYBREAK THURSDAY. I HAVE TRENDED TEMPS UP
A LITTLE.
TEMPERATURE FORECAST THURSDAY IS COMPLICATED BY TIMING OF ARCTIC
FRONT ARRIVAL. NAM/GFS CONTINUE TO SHOW FROPA IN THE 12-18Z TIME
PERIOD...WITH THE LATEST RUNS OF THE ECMWF/GEM SEEM TO FAVOR AN
AFTERNOON FRONTAL PASSAGE. CONTINUITY AND PERSONAL EXPERIENCE WOULD
FAVOR THE QUICKER PASSAGE...HOWEVER WITH ABOUT 6HR OF SPREAD IN
SOLUTIONS THIS COULD HAVE A LARGE IMPACT ON HIGH TEMPS. GOING BY THE
COLDER END OF GUIDANCE NORTHERN HALF OF THE CWA LIKELY WOULDNT MAKE
IT ABOVE FREEZING AND TEMPS WOULD BE FALLING TO THE 20S BY MID
AFTERNOON. WARMER END OF GUIDANCE ALLOWS ENOUGH OF A WINDOW FOR
TEMPS TO RISE TO AT LEAST THE UPPER 40S IF NOT THE LOW 50S ACROSS
THE SOUTH. I NUDGED THE FORECAST TOWARDS THE FASTER
GUIDANCE...HOWEVER CONFIDENCE IS NOT PARTICULARLY HIGH ON HOW THIS
WILL TIME OUT. WE COULD END UP SEEING HIGHS IN THE NORTH OCCURRING
IN THE EARLY MORNING NEAR SUNRISE.
GUIDANCE CONTINUES TO SHOW INCREASING MID LEVEL MOISTURE AND WEAK
FORCING FROM THE NORTHWEST...SO I COULDNT RULE OUT A FEW FLURRIES
BY LATE THURSDAY AFTERNOON. I LEFT MENTION IN PLACE OVER YUMA
COUNTY IN LINE WITH PREVIOUS FORECAST.
.LONG TERM...(THURSDAY NIGHT THROUGH WEDNESDAY)
ISSUED AT 234 PM MST WED DEC 18 2013
WESTERLY FLOW WILL CONTINUE THROUGH FRIDAY AHEAD OF A TROUGH MOVING
SOUTHEAST FROM SOUTHERN CALIFORNIA. THE TROUGH WILL MOVE EAST INTO
EASTERN NEW MEXICO SATURDAY. SURFACE HIGH PRESSURE WILL MOVE INTO
THE CENTRAL PLAINS THURSDAY NIGHT AND FRIDAY. A SURFACE TROUGH WILL
MOVE INTO EASTERN COLORADO FRIDAY NIGHT. THIS TROUGH WILL MOVE SOUTH
INTO TEXAS SATURDAY WITH A COLD FRONT FOLLOWING.
THERE WILL BE SOME FLURRIES POSSIBLE THURSDAY NIGHT AS COLDER AIR
FILTERS INTO THE REGION BEHIND THE COLD FRONT. PLAN TO CONTINUE THIS
AREA OF FLURRIES OVER THE NORTHWEST FA WHERE H8-7 LAYER MEAN
MOISTURE IS BEST. OTHERWISE POPS WILL BE NIL THROUGH FRIDAY NIGHT
DUE TO SUBSIDENCE. THE UPPER TROUGH OVER EASTERN NEW MEXICO WILL
BRING A SLIGHT CHANCE OF LIGHT SNOW TO THE FAR SOUTHEAST ZONES
SATURDAY AS DYNAMICS MOVE ACROSS SOUTHWEST AND SOUTHCENTRAL KANSAS.
MIN TEMPERATURES THURSDAY NIGHT WILL FALL INTO THE LOWER TEENS AND
COULD BE COLDER IF SKIES CLEAR. THE COLDEST AIR MOVES AWAY SO THAT
LOW TEMPERATURES FRIDAY NIGHT WILL BE IN THE UPPER TEENS. MAX
TEMPERATURES WILL RANGE FROM 30 TO AROUND 35 FRIDAY AND 35 TO AROUND
40 SATURDAY.
IN THE EXTENDED...(SATURDAY NIGHT THROUGH WEDNESDAY)...
SOME LIGHT SNOW WILL BE POSSIBLE SATURDAY NIGHT AS THE ABOVE
MENTIONED TROUGH MOVES EAST ACROSS THE CENTRAL/SOUTHERN PLAINS.
SLIGHT CHANCE POPS WILL BE OVER THE EXTREME SOUTHEAST FA WHERE
MOISTURE IS BEST. UPPER FLOW WILL BECOME NORTHWEST SUNDAY AND CONTINUE
THROUGH WEDNESDAY. SUBSIDENCE DURING THIS TIME WILL BRING DRY
CONDITIONS.
MIN TEMPERATURES WILL RANGE FROM THE TEENS SATURDAY THROUGH SUNDAY
NIGHTS WARMING TO THE LOWER 20S MONDAY THROUGH WEDNESDAY NIGHTS.
MAX TEMPERATURES SUNDAY WILL BE IN THE LOWER 30S. SOME WARMING INTO
THE 40S WILL OCCUR MONDAY THROUGH WEDNESDAY.
&&
.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z THURSDAY EVENING)
ISSUED AT 422 PM MST WED DEC 18 2013
VFR CONDITIONS SHOULD LAST THROUGH THE TAF PERIOD. THE ONLY
QUESTIONABLE TIME PERIOD MAY BE LATE IN THE TAF PERIOD TOWARDS 0Z
TOMORROW FOR KMCK. WINDS WILL BE LIGHT AND VARIABLE THIS EVENING AND
OVERNIGHT WITH INCREASING HIGH CLOUDS. A COLD FRONT WILL MOVE
THROUGH THE TERMINALS EARLY TOMORROW...WITH WINDS SHIFTING TO THE
EAST-NORTHEAST AND INCREASING ABOVE 12 KTS BY MID-LATE MORNING FOR
KMCK AND LATE MORNING FOR KGLD. CEILINGS WILL BEGIN TO DECLINE
BEHIND THE FRONT...STAYING WITHIN VFR CRITERIA AS OF RIGHT NOW.
THE GFS BUFKIT SOUNDING INDICATES LOW CLOUD LAYER DEVELOPING AT
KMCK EARLY TOMORROW AFTERNOON...WITH THE NAM BUFKIT SOUNDING
INDICATING THE LOW CLOUD LAYER AFTER 0Z. THEREFORE...COULD
ANTICIPATE THE POSSIBILITY OF LOWER CEILINGS AT KMCK TOMORROW
SLIGHTLY BEFORE OR AFTER 0Z...BUT KEPT VFR CONDITIONS AS OF RIGHT NOW.
&&
.GLD WATCHES/WARNINGS/ADVISORIES...
KS...NONE.
CO...NONE.
NE...NONE.
&&
$$
UPDATE...JRM
SHORT TERM...DR
LONG TERM...FS
AVIATION...ALW
AREA FORECAST DISCUSSION
NWS GOODLAND KS
434 PM MST WED DEC 18 2013
.SHORT TERM...(THIS AFTERNOON THROUGH THURSDAY)
ISSUED AT 100 PM MST WED DEC 18 2013
LATEST WV IMAGERY AND RAP H5 ANALYSIS INDICATES WESTERLY ZONAL FLOW
IN PLACE ACROSS THE UNITED STATES...WITH TWO SHORTWAVE TROUGHS
UPSTREAM OFF THE WEST COAST. THE FIRST TROUGH IS CENTERED OVER
BRITISH COLUMBIA...WITH THE SECOND JUST WEST OF THE BAJA PENINSULA.
AT THE SURFACE A TROUGH OF LOW PRESSURE EXTENDS FROM EASTERN
COLORADO AND ACROSS SOUTH WEST NEBRASKA. A COLD FRONT IS IN PLACE
ACROSS CENTRAL MONTANA AND NORTH DAKOTA WITH AN ARCTIC HIGH PRESSURE
SYSTEM LURKING TO THE NORTH OF THE FEATURE READY TO MAKE A TREK
SOUTH INTO THE PLAINS.
WITH WESTERLY CROSS MOUNTAIN FLOW AND EMBEDDED UPPER LEVEL ENERGY
CONTINUE TO MOVE EAST I WOULD EXPECT CLOUD COVER TO BEGIN TO
INCREASE ONCE AGAIN TONIGHT...ESPECIALLY AFTER MIDNIGHT AS A TROUGH
BEGINS TO MOVE FROM THE PAC NW AND DEEPEN ACROSS THE GREAT BASIN.
CLOUD COVER COULD HAVE A NEGATIVE IMPACT ON RADIATIONAL COOLING...AND
I WAS NOT CONFIDENT IN HOW LOW WE WILL ACTUALLY DROP BEFORE WINDS
POSSIBLY INCREASE TOWARDS DAYBREAK THURSDAY. I HAVE TRENDED TEMPS UP
A LITTLE.
TEMPERATURE FORECAST THURSDAY IS COMPLICATED BY TIMING OF ARCTIC
FRONT ARRIVAL. NAM/GFS CONTINUE TO SHOW FROPA IN THE 12-18Z TIME
PERIOD...WITH THE LATEST RUNS OF THE ECMWF/GEM SEEM TO FAVOR AN
AFTERNOON FRONTAL PASSAGE. CONTINUITY AND PERSONAL EXPERIENCE WOULD
FAVOR THE QUICKER PASSAGE...HOWEVER WITH ABOUT 6HR OF SPREAD IN
SOLUTIONS THIS COULD HAVE A LARGE IMPACT ON HIGH TEMPS. GOING BY THE
COLDER END OF GUIDANCE NORTHERN HALF OF THE CWA LIKELY WOULDNT MAKE
IT ABOVE FREEZING AND TEMPS WOULD BE FALLING TO THE 20S BY MID
AFTERNOON. WARMER END OF GUIDANCE ALLOWS ENOUGH OF A WINDOW FOR
TEMPS TO RISE TO AT LEAST THE UPPER 40S IF NOT THE LOW 50S ACROSS
THE SOUTH. I NUDGED THE FORECAST TOWARDS THE FASTER
GUIDANCE...HOWEVER CONFIDENCE IS NOT PARTICULARLY HIGH ON HOW THIS
WILL TIME OUT. WE COULD END UP SEEING HIGHS IN THE NORTH OCCURRING
IN THE EARLY MORNING NEAR SUNRISE.
GUIDANCE CONTINUES TO SHOW INCREASING MID LEVEL MOISTURE AND WEAK
FORCING FROM THE NORTHWEST...SO I COULDNT RULE OUT A FEW FLURRIES
BY LATE THURSDAY AFTERNOON. I LEFT MENTION IN PLACE OVER YUMA
COUNTY IN LINE WITH PREVIOUS FORECAST.
.LONG TERM...(THURSDAY NIGHT THROUGH WEDNESDAY)
ISSUED AT 234 PM MST WED DEC 18 2013
WESTERLY FLOW WILL CONTINUE THROUGH FRIDAY AHEAD OF A TROUGH MOVING
SOUTHEAST FROM SOUTHERN CALIFORNIA. THE TROUGH WILL MOVE EAST INTO
EASTERN NEW MEXICO SATURDAY. SURFACE HIGH PRESSURE WILL MOVE INTO
THE CENTRAL PLAINS THURSDAY NIGHT AND FRIDAY. A SURFACE TROUGH WILL
MOVE INTO EASTERN COLORADO FRIDAY NIGHT. THIS TROUGH WILL MOVE SOUTH
INTO TEXAS SATURDAY WITH A COLD FRONT FOLLOWING.
THERE WILL BE SOME FLURRIES POSSIBLE THURSDAY NIGHT AS COLDER AIR
FILTERS INTO THE REGION BEHIND THE COLD FRONT. PLAN TO CONTINUE THIS
AREA OF FLURRIES OVER THE NORTHWEST FA WHERE H8-7 LAYER MEAN
MOISTURE IS BEST. OTHERWISE POPS WILL BE NIL THROUGH FRIDAY NIGHT
DUE TO SUBSIDENCE. THE UPPER TROUGH OVER EASTERN NEW MEXICO WILL
BRING A SLIGHT CHANCE OF LIGHT SNOW TO THE FAR SOUTHEAST ZONES
SATURDAY AS DYNAMICS MOVE ACROSS SOUTHWEST AND SOUTHCENTRAL KANSAS.
MIN TEMPERATURES THURSDAY NIGHT WILL FALL INTO THE LOWER TEENS AND
COULD BE COLDER IF SKIES CLEAR. THE COLDEST AIR MOVES AWAY SO THAT
LOW TEMPERATURES FRIDAY NIGHT WILL BE IN THE UPPER TEENS. MAX
TEMPERATURES WILL RANGE FROM 30 TO AROUND 35 FRIDAY AND 35 TO AROUND
40 SATURDAY.
IN THE EXTENDED...(SATURDAY NIGHT THROUGH WEDNESDAY)...
SOME LIGHT SNOW WILL BE POSSIBLE SATURDAY NIGHT AS THE ABOVE
MENTIONED TROUGH MOVES EAST ACROSS THE CENTRAL/SOUTHERN PLAINS.
SLIGHT CHANCE POPS WILL BE OVER THE EXTREME SOUTHEAST FA WHERE
MOISTURE IS BEST. UPPER FLOW WILL BECOME NORTHWEST SUNDAY AND CONTINUE
THROUGH WEDNESDAY. SUBSIDENCE DURING THIS TIME WILL BRING DRY
CONDITIONS.
MIN TEMPERATURES WILL RANGE FROM THE TEENS SATURDAY THROUGH SUNDAY
NIGHTS WARMING TO THE LOWER 20S MONDAY THROUGH WEDNESDAY NIGHTS.
MAX TEMPERATURES SUNDAY WILL BE IN THE LOWER 30S. SOME WARMING INTO
THE 40S WILL OCCUR MONDAY THROUGH WEDNESDAY.
&&
.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z THURSDAY EVENING)
ISSUED AT 422 PM MST WED DEC 18 2013
VFR CONDITIONS SHOULD LAST THROUGH THE TAF PERIOD. THE ONLY
QUESTIONABLE TIME PERIOD MAY BE LATE IN THE TAF PERIOD TOWARDS 0Z
TOMORROW FOR KMCK. WINDS WILL BE LIGHT AND VARIABLE THIS EVENING AND
OVERNIGHT WITH INCREASING HIGH CLOUDS. A COLD FRONT WILL MOVE
THROUGH THE TERMINALS EARLY TOMORROW...WITH WINDS SHIFTING TO THE
EAST-NORTHEAST AND INCREASING ABOVE 12 KTS BY MID-LATE MORNING FOR
KMCK AND LATE MORNING FOR KGLD. CEILINGS WILL BEGIN TO DECLINE
BEHIND THE FRONT...STAYING WITHIN VFR CRITERIA AS OF RIGHT NOW.
THE GFS BUFKIT SOUNDING INDICATES LOW CLOUD LAYER DEVELOPING AT
KMCK EARLY TOMORROW AFTERNOON...WITH THE NAM BUFKIT SOUNDING
INDICATING THE LOW CLOUD LAYER AFTER 0Z. THEREFORE...COULD
ANTICIPATE THE POSSIBILITY OF LOWER CEILINGS AT KMCK TOMORROW
SLIGHTLY BEFORE OR AFTER 0Z...BUT KEPT VFR CONDITIONS AS OF RIGHT NOW.
&&
.GLD WATCHES/WARNINGS/ADVISORIES...
KS...NONE.
CO...NONE.
NE...NONE.
&&
$$
SHORT TERM...DR
LONG TERM...FS
AVIATION...ALW
AREA FORECAST DISCUSSION
NWS PADUCAH KY
942 PM CST Wed Dec 18 2013
.UPDATE...
ISSUED AT 942 PM CST WED DEC 18 2013
South winds, just off the surface, are increasing over the
region this evening. KVWX VAD Wind profile indicates 45kts at
925mb and 50kts at 850mb as 0318Z. Cannot see surface winds
decreasing substantially overnight, so we may not see much fall
in temperatures. Just updated to increase lows and winds in some
locations. Leaned on the LAMP and RUC data for the update.
The dewpoints have also been fun to account for, with drier than
expected air over the southern Pennyrile, and increasing moisture
in SEMO. The HRRR seems to have the best handle on the dry air,
but it is likely too aggressive in moistening the southwest. Tried
to just blend it in with the existing forecast to at least head in
the right direction with the trends.
&&
.SHORT TERM...(This Evening through Thursday)
ISSUED AT 152 PM CST WED DEC 18 2013
Southerly winds will keep temperatures up above freezing for most
locations overnight for the first time in a long time. Even though
we will have nearly the lowest sun angle of the year...the snow
field retreats and southerly winds combine to push temps to near 60
across southern portions of the heartland Thursday. High pressure
will gradually be forced off the southeast coast as the upper level
trough digs southeast before ejecting northeast into the heartland.
Otherwise very few changes to the short term.
.LONG TERM...(Thursday Night through Wednesday)
ISSUED AT 152 PM CST WED DEC 18 20131
Will be warm sector Thursday night and most of Friday. Scattered
shower activity expected as the atmosphere moistens up and
impulses move SW/NE across the area. Not much organization wise
given no boundaries to focus on. Mainly mid level support and WAA.
Best chance of thunder Friday should be across the SRN 1/3 of the
area. Late Friday afternoon a strong cold front will enter into
our NW CWFA. The front is forecast to push southeast into our area
and then stall. Showers/TSRA should increase after midnight Friday
night with convective focus near and just north of the boundary.
The boundary should stall somewhere near the Ohio River. The front
will then lift back north as a warm front Saturday as the upper
flow backs and surface low pressure forms along the front, ending
up over west AR by 00z Sun ahead of a strong H5 moving east along
the US/Mexico border into the srn Plains. The convection/locally heavy
rains should pick up Saturday. The axis may shift slowly northwest
with time, in line with the movement of the front.
Saturday night, the front should park across se MO into srn IL
with areas south into west KY (including sw IN) warm sector. Again
with respect to greatest QPF we are leaning away from the GFS as
the axis seems too far east into the warm sector, whereas the
ECMWF focuses the best QPF more in line with strong 700mb
transport and 850mb speed convergence, which is more to the west
and closer to the surface boundary. WPC continues to lean toward this
solution as well. Having said that, would not be surprised to see
an adjustment back to the east just a tad, but not as far as the
GFS. All said and done, main focus Friday night through early
Sunday, 1 1/2-3" rain amounts west KY, increasing to 3-4" or so
from about the Ohio River on north and west. Higher amounts
possible. Will continue with our Hydrologic Outlook product, to
detail the prospects of flooding. As we`ve stated since Monday,
precipitable water values are forecast to remain very high,
1.5-1.75". The potential precip efficiency is cause for concern
given the saturated ground conditions. Concern is mainly small
creeks, ditches, roads that typically flood. Could be a lot of
standing water in fields, etc.
Confidence continues to increase there may be severe storms,
primarily Saturday night, and especially SE of a Poplar Bluff
Missouri, to Evansville Indiana line. This is when we see a notable
increase in forecast winds, from 65-70kts around 850mb up to 85-95
kts 700-500mb, and veering. This coupled with a period of surface
based instability Saturday night in the warm sector, means we could
see some quasi linear segments form and possibly produce damaging
wind gusts and perhaps the typical brief spin up tornado or two we
typically see with a QLCS setup.
Front will blast through Sunday, with precip chances lowering
rapidly from west to east. Temperatures will fall through the day.
Sunday night, mainly dry, though cannot rule out entirely very
light snow or flurries until the mid level wave passes to our
east.
Monday through Christmas day will be dry and seasonably chilly as
strong high pressure builds across the region.
&&
.AVIATION...
ISSUED AT 543 PM CST WED DEC 18 2013
For the 00z Thursday TAF forecast, VFR conditions will dominate
all WFO PAH TAF sites. Cirrus cloud dominated forecast will be in
force for all locations through early Thursday afternoon. Some
4-5kft AGL clouds will move into KCGI/KPAH TAF sites with the
initial development of warm advection clouds ahead of frontal
boundary over Missouri.
&&
.PAH WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
MO...NONE.
IN...NONE.
KY...NONE.
&&
$$
UPDATE...DRS
SHORT TERM...KH
LONG TERM...CN
AVIATION...Smith
AREA FORECAST DISCUSSION
NWS JACKSON KY
342 PM EST TUE DEC 17 2013
.SHORT TERM...(THIS EVENING THROUGH WEDNESDAY NIGHT)
ISSUED AT 331 PM EST TUE DEC 17 2013
MODELS HAVE BEEN CHANGING THROUGHOUT THE LAST 24 HOURS...MAKING IT
HARD TO PINPOINT AN EXACT FORECAST UNTIL LOOKING AT ONGOING
CONDITIONS. SO FAR TODAY...THE HRRR SEEMS TO BE INITIALIZING THE
BEST WITH ONGOING CONDITIONS...AND THE OTHER HIRES MODELS HAVE
FOLLOWED SUIT THROUGHOUT THE DAY. BASED ON CURRENT TRENDS...AND
LATEST HIRES MODEL DATA...FAVOR A LESS IMPACTFUL EVENING WITH MAINLY
LIGHT RAIN...ENDING BEFORE MIDNIGHT IN MOST AREAS.
WITH TEMPERATURES WELL ABOVE FREEZING IN MOST LOCATIONS RIGHT
NOW...AND ROAD TEMPS SITTING ABOVE FREEZING AS WELL...DO NOT EXPECT
ANY IMPACTS OTHER THAN SOME LIGHT RAIN...MAINLY NORTH OF THE
MOUNTAIN PARKWAY. CLOUD COVER CURRENTLY EXTENDS SOUTHWARD ACROSS
MUCH OF THE CWA. AS PRECIPITATION QUICKLY MOVES OFF TO THE
EAST...TEMPERATURES WILL COOL WITH LOSS OF DAYTIME HEATING...BUT
LATEST DATA SUPPORTS THE IDEA THAT TEMPS WILL STILL BE ABOVE
FREEZING THROUGH MOST OF THE EVENING. ANY SNOW THAT DOES FALL WILL
BE LATE IN THE EVENING ACROSS THE FAR EASTERN CWA /PIKE COUNTY/...AS
WELL AS ACROSS SOME OF THE HIGHEST TERRAIN NEAR THE VIRGINIA BORDER.
DROPPED SNOW TOTALS SUBSTANTIALLY...WITH ONLY A COUPLE TENTHS
EXPECTED IN THE HIGHEST TERRAIN. NEIGHBORING OFFICES SEEM TO HAVE
FOLLOWED SUIT WITH THIS LOWER IMPACT SOLUTION AS WELL.
THE PRECIPITATION SHOULD CLEAR EARLY IN THE NIGHT...WITH DRY AND
COLDER AIR FILTERING IN BEHIND...EFFECTIVELY CUTTING OFF THE CLOUD
COVER FROM WEST TO EAST. AS THIS COLDER AIRMASS TAKES HOLD...AND
CLOUDS CLEAR...EXPECT TEMPS TO MIX OUT OVERNIGHT INTO THE MID 20S
ACROSS MUCH OF THE REGION. SUNNY SKIES WILL FINALLY MAKE AN
APPEARANCE DURING THE DAY TOMORROW AS HIGH PRESSURE REMAINS IN
CONTROL. TEMPERATURES WILL BE ON THE COOLER SIDE COMPARED TO
TODAY...BUT WILL STILL BE ABLE TO WARM UP TO ABOUT THE 40 DEGREE
MARK. NAM12 FORECAST SOUNDINGS SHOW THE ATMOSPHERE BECOMING QUITE
DRY...WITH DEW POINTS DROPPING SUBSTANTIALLY. THIS WILL ESPECIALLY
BE THE CASE IN THE HIGHER TERRAIN WEDNESDAY NIGHT...WHERE DEW POINTS
COULD DROP AS LOW AS 9 DEGREES. OVERNIGHT LOW TEMPS WILL DROP TO
AROUND FREEZING OR SLIGHTLY BELOW...WITH A GOOD SET UP FOR A RIDGE
VALLEY SPLIT TO OCCUR.
.LONG TERM...(THURSDAY THROUGH TUESDAY)
ISSUED AT 341 PM EST TUE DEC 17 2013
THE EXTENDED FORECAST PERIOD BEGINS ON THURSDAY WITH A MAINLY
ZONAL PATTERN OVER THE CONUS WITH AN UPPER LEVEL LOW OVER THE
SOUTHWEST. THE BIG QUESTION BECOMES THE TIMING OF THE UPPER LOW AS
IT MOVES TO THE EAST AND WHERE THE FRONT SETS UP OVER THE OHIO
VALLEY. THE CURRENT TREND IN THE MODELS IS FOR A STRONGER LOW TO
FORM ON THE FRONT TO THE WEST OF THE AREA. THIS SOLUTION WILL
CREATE A SHARP WAVE ON THE FRONT AND PUSH A WARM FRONT TO THE NORTH
OF THE AREA. THIS SOLUTION WOULD PRODUCE MUCH LESS RAINFALL BECAUSE
THE STATIONARY FRONT WOULD STAY TO THE WEST AND NORTH OF EASTERN
KENTUCKY. THE JURY IS REALLY STILL OUT ON THIS SOLUTION AND WOULD
NOT BE TOO SURPRISED TO SEE A COUPLE DIFFERENT SOLUTIONS BEFORE THE
WEEKEND GETS HERE. AS SUCH...TIMING OF THE SYSTEM AND THE AMOUNT OF
RAINFALL IS FAIRLY LOW CONFIDENCE. IN ADDITION...HAVE SEEN THE
MODELS STRUGGLE TIME AND TIME AGAIN WITH TRYING TO NAIL DOWN
TRANSITIONS IN THE PATTERN LIKE THE ONE WE ARE SEEING. DID TREND THE
FORECAST TO THE NEWER MODEL BLEND. ALSO WITH THIS SOLUTION...THERE
WILL NOT BE MUCH TIME TO GET ANY COLD AIR INTO THE AREA AS THE FRONT
MOVES THROUGH. THIS WILL DECREASE THE CHANCES FOR WINTRY
PRECIPITATION ON THE BACK END OF THE FRONT.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z WEDNESDAY AFTERNOON)
ISSUED AT 1259 PM EST TUE DEC 17 2013
LOW CIGS CONTINUE ACROSS THE NORTHER CWA AS A SHORTWAVE CONTINUES TO
MOVE ACROSS THE REGION. THIS HAS PRODUCED A LINE OF WEAK SHOWERS
MAINLY NORTH OF THE MOUNTAIN PARKWAY...POSING LITTLE THREAT TO VIS.
THE ONLY TAF SITE WHICH MAY POSSIBLY BE IMPACTED BY THIS RAIN IS
KSJS...BUT IMPACTS WILL BE MINIMAL. AS WE CONTINUE THROUGHOUT THE
EVENING...EXPECT THE SHORTWAVE TO SHIFT SE...BRINGING INCREASING POPS
TO THE FAR SE COUNTIES...MAINLY ALONG THE VA AND WV BORDER. AS
TEMPERATURES FALL THROUGHOUT THE EVENING...THIS PRECIPITATION WILL
CHANGE OVER TO SNOW. BUT ONCE AGAIN...THE ONLY TAF SITE WHICH SHOULD
FEEL ANY IMPACTS FROM THIS WILL BE KSJS. DROPPED THE CIGS AT KSJS TO
MVFR AS THE PRECIPITATION MOVES THROUGH...BEFORE CLEARING OUT LATE
TONIGHT AS HIGH PRESSURE MOVES IN OVERHEAD. FOR THE REMAINING TAF
SITES...SOME LOW CLOUDS MAY BE FELT LATER IN THE EVENING AS THE
SHORTWAVE MOVES SE ACROSS THE AREA. HOWEVER...BASED ON LATEST NAM12
AND GFSLAMP DATA...THESE CLOUDS SHOULD STAY RIGHT AT OR SLIGHTLY
ABOVE THE VFR RANGE...BEFORE CLEARING OUT LATE TONIGHT.
AS FAR AS WINDS...HIGH PRESSURE GRADIENTS ACROSS THE REGION TODAY AND
THIS EVENING SHOULD LEAD TO SOME POSSIBLE GUSTS IN THE 15 TO 20KT
RANGE. UNFORTUNATELY...RECENT OBSERVATIONS HAVE NOT SHOWN THIS
MATERIALIZING AS WELL...THOUGH THE POTENTIAL IS MOST CERTAINLY
STILL THERE. WENT AHEAD AND KEPT WINDS AT 10KTS OR SO...BUT DID TAKE
OUT GUSTS THROUGH THIS EVENING. AS MENTIONED ABOVE...WILL CONTINUE TO
MONITOR THIS AS WELL IN CASE CHANGES NEED TO BE MADE.
&&
.JKL WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...JMW
LONG TERM...JJ
AVIATION...JMW
AREA FORECAST DISCUSSION
NWS JACKSON KY
332 PM EST TUE DEC 17 2013
.SHORT TERM...(THIS EVENING THROUGH WEDNESDAY NIGHT)
ISSUED AT 331 PM EST TUE DEC 17 2013
MODELS HAVE BEEN CHANGING THROUGHOUT THE LAST 24 HOURS...MAKING IT
HARD TO PINPOINT AN EXACT FORECAST UNTIL LOOKING AT ONGOING
CONDITIONS. SO FAR TODAY...THE HRRR SEEMS TO BE INITIALIZING THE
BEST WITH ONGOING CONDITIONS...AND THE OTHER HIRES MODELS HAVE
FOLLOWED SUIT THROUGHOUT THE DAY. BASED ON CURRENT TRENDS...AND
LATEST HIRES MODEL DATA...FAVOR A LESS IMPACTFUL EVENING WITH MAINLY
LIGHT RAIN...ENDING BEFORE MIDNIGHT IN MOST AREAS.
WITH TEMPERATURES WELL ABOVE FREEZING IN MOST LOCATIONS RIGHT
NOW...AND ROAD TEMPS SITTING ABOVE FREEZING AS WELL...DO NOT EXPECT
ANY IMPACTS OTHER THAN SOME LIGHT RAIN...MAINLY NORTH OF THE
MOUNTAIN PARKWAY. CLOUD COVER CURRENTLY EXTENDS SOUTHWARD ACROSS
MUCH OF THE CWA. AS PRECIPITATION QUICKLY MOVES OFF TO THE
EAST...TEMPERATURES WILL COOL WITH LOSS OF DAYTIME HEATING...BUT
LATEST DATA SUPPORTS THE IDEA THAT TEMPS WILL STILL BE ABOVE
FREEZING THROUGH MOST OF THE EVENING. ANY SNOW THAT DOES FALL WILL
BE LATE IN THE EVENING ACROSS THE FAR EASTERN CWA /PIKE COUNTY/...AS
WELL AS ACROSS SOME OF THE HIGHEST TERRAIN NEAR THE VIRGINIA BORDER.
DROPPED SNOW TOTALS SUBSTANTIALLY...WITH ONLY A COUPLE TENTHS
EXPECTED IN THE HIGHEST TERRAIN. NEIGHBORING OFFICES SEEM TO HAVE
FOLLOWED SUIT WITH THIS LOWER IMPACT SOLUTION AS WELL.
THE PRECIPITATION SHOULD CLEAR EARLY IN THE NIGHT...WITH DRY AND
COLDER AIR FILTERING IN BEHIND...EFFECTIVELY CUTTING OFF THE CLOUD
COVER FROM WEST TO EAST. AS THIS COLDER AIRMASS TAKES HOLD...AND
CLOUDS CLEAR...EXPECT TEMPS TO MIX OUT OVERNIGHT INTO THE MID 20S
ACROSS MUCH OF THE REGION. SUNNY SKIES WILL FINALLY MAKE AN
APPEARANCE DURING THE DAY TOMORROW AS HIGH PRESSURE REMAINS IN
CONTROL. TEMPERATURES WILL BE ON THE COOLER SIDE COMPARED TO
TODAY...BUT WILL STILL BE ABLE TO WARM UP TO ABOUT THE 40 DEGREE
MARK. NAM12 FORECAST SOUNDINGS SHOW THE ATMOSPHERE BECOMING QUITE
DRY...WITH DEW POINTS DROPPING SUBSTANTIALLY. THIS WILL ESPECIALLY
BE THE CASE IN THE HIGHER TERRAIN WEDNESDAY NIGHT...WHERE DEW POINTS
COULD DROP AS LOW AS 9 DEGREES. OVERNIGHT LOW TEMPS WILL DROP TO
AROUND FREEZING OR SLIGHTLY BELOW...WITH A GOOD SET UP FOR A RIDGE
VALLEY SPLIT TO OCCUR.
.LONG TERM...(WEDNESDAY NIGHT THROUGH MONDAY)
ISSUED AT 415 AM EST TUE DEC 17 2013
THE EXTENDED FORECAST PERIOD BEGINS ON WEDNESDAY NIGHT WITH A MAINLY
ZONAL PATTERN OVER THE CONUS BUT IN TRANSITION. AN UPPER LEVEL LOW
COMES ASHORE OVER THE SOUTHWEST AND BAJA REGION AND BECOMES CUT OFF
BUT STILL INFLUENCE BY THE UPPER LEVEL FLOW AS IT CREEPS EASTWARD.
MEANWHILE...THE NORTHERN PORTION OF THE STREAM BRINGS A SEPARATE
SHORTWAVE INTO THE PLAINS AND INTO THE MS RIVER VALLEY BY FRIDAY.
THIS WILL LEAD TO LOW DEVELOPMENT AT THE SURFACE OVER THE UPPER MS
RIVER VALLEY AS A COLD FRONT BEGINS TO PUSH INTO THE OHIO VALLEY BY
FRIDAY NIGHT. THIS FRONT BECOMES STALLED OUT THANKS TO A STAUNCH
RIDGE OVER THE ATLANTIC OCEAN. THIS HAS BECOME A POINT OF CONCERN
OVER THE PAST SEVERAL DAYS OF THE MODEL RUNS AS THIS EVENT CONTINUES
TO TAKE SHAPE.
PRECIP SHOULD BEGIN TO ENTER THE AREA ON FRIDAY AND CONTINUE THROUGH
THE WEEKEND AS THE FRONT STALLS. PLENTY OF MOISTURE IS AVAILABLE AS
THIS SYSTEM DEVELOPS BUT MOST OF THE UPPER LEVEL DYNAMICS HAVE
ALREADY PASSED OFF TO THE NORTHEAST. HOWEVER...BY SATURDAY...THE
AFOREMENTIONED CLOSED LOW OVER THE SOUTHWEST FINALLY OPENS AND EJECTS
EASTWARD INTO THE LOWER MS RIVER VALLEY. THIS WILL HELP GENERATE
RAPID CYCLOGENESIS AT THE SURFACE OVER THE SOUTHERN PLAINS ALONG THE
STALLED FRONTAL BOUNDARY AS A DEEP LOW DEVELOPS. ABUNDANT MOISTURE
WILL THEN STREAM NORTHWARD AS A WARM FRONT MOVES NORTH INTO THE
LOWER OHIO VALLEY BY SATURDAY NIGHT. THE LOW LEVEL JET SETS UP WITH
50 TO 70 KNOTS TRANSPORTING WARM AIR AND AMPLE MOISTURE NORTHWARD.
THIS WILL BRING SOAKING RAINS OVER EASTERN KENTUCKY. THE WARM FRONT
WILL MOVE NORTH INTO OHIO BY SUNDAY MORNING AS A STRONG COLD FRONT
QUICKLY HEADS EAST INTO EASTERN KENTUCKY SUNDAY AFTERNOON. HERE IN
LIES A POSSIBLE FORECAST PROBLEM AS THE FRONT MOVES EAST QUITE
QUICKLY BUT MODELS KEEP THE HIGH OVER THE ATLANTIC THAT STALLED OUT
THE PREVIOUS FRONT BARELY WEAKENED OR CENTERED ANY FARTHER EAST. THE
EURO AND GFS HAVE COME INTO AGREEMENT KEEPING THE FRONT PROGRESSIVE
AND NOW HAVE A FEW RUNS OF CONSISTENCY SO WILL KEEP THE QUICKER EXIT
BUT THIS WILL BE AN ELEMENT OF THE FORECAST TO WATCH CLOSELY. THIS
TIME OF YEAR...AND WITH THE MOISTURE THIS SYSTEM HAS TO WORK
WITH...A STALLED BOUNDARY WOULD CERTAINLY CAUSE FLOODING TO BE A
CONCERN.
THE FRONT MOVES THROUGH THE AREA BY MONDAY MORNING WITH THE COLDER
AIR ADVECTING INTO EASTERN KENTUCKY IN STRONG NORTHWEST FLOW. A WEAK
WAVE BEHIND THE FRONT WILL SLIDE SOUTHEAST BRINGING JUST ENOUGH
MOISTURE FOR SOME RAIN CHANGING TO SNOW BEHIND THE FRONT. WIND FLOW
IS ALSO JUST ABOUT FAVORABLE FOR UPSLOPE TYPE SNOWFALLS. THE DEPTH
OF MOISTURE IS IN QUESTION BEHIND THE FRONT SO ANY SNOWFALL MAY ALSO
BE SHORT IN DURATION AND CONFINED TO THE BLUEGRASS COUNTIES AS TEMPS
MAY NOT DROP OFF FAST ENOUGH BEFORE ALL THE LIST AND MOISTURE EXIT
EASTERN KENTUCKY BY MONDAY EVENING.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z WEDNESDAY AFTERNOON)
ISSUED AT 1259 PM EST TUE DEC 17 2013
LOW CIGS CONTINUE ACROSS THE NORTHER CWA AS A SHORTWAVE CONTINUES TO
MOVE ACROSS THE REGION. THIS HAS PRODUCED A LINE OF WEAK SHOWERS
MAINLY NORTH OF THE MOUNTAIN PARKWAY...POSING LITTLE THREAT TO VIS.
THE ONLY TAF SITE WHICH MAY POSSIBLY BE IMPACTED BY THIS RAIN IS
KSJS...BUT IMPACTS WILL BE MINIMAL. AS WE CONTINUE THROUGHOUT THE
EVENING...EXPECT THE SHORTWAVE TO SHIFT SE...BRINGING INCREASING POPS
TO THE FAR SE COUNTIES...MAINLY ALONG THE VA AND WV BORDER. AS
TEMPERATURES FALL THROUGHOUT THE EVENING...THIS PRECIPITATION WILL
CHANGE OVER TO SNOW. BUT ONCE AGAIN...THE ONLY TAF SITE WHICH SHOULD
FEEL ANY IMPACTS FROM THIS WILL BE KSJS. DROPPED THE CIGS AT KSJS TO
MVFR AS THE PRECIPITATION MOVES THROUGH...BEFORE CLEARING OUT LATE
TONIGHT AS HIGH PRESSURE MOVES IN OVERHEAD. FOR THE REMAINING TAF
SITES...SOME LOW CLOUDS MAY BE FELT LATER IN THE EVENING AS THE
SHORTWAVE MOVES SE ACROSS THE AREA. HOWEVER...BASED ON LATEST NAM12
AND GFSLAMP DATA...THESE CLOUDS SHOULD STAY RIGHT AT OR SLIGHTLY
ABOVE THE VFR RANGE...BEFORE CLEARING OUT LATE TONIGHT.
AS FAR AS WINDS...HIGH PRESSURE GRADIENTS ACROSS THE REGION TODAY AND
THIS EVENING SHOULD LEAD TO SOME POSSIBLE GUSTS IN THE 15 TO 20KT
RANGE. UNFORTUNATELY...RECENT OBSERVATIONS HAVE NOT SHOWN THIS
MATERIALIZING AS WELL...THOUGH THE POTENTIAL IS MOST CERTAINLY
STILL THERE. WENT AHEAD AND KEPT WINDS AT 10KTS OR SO...BUT DID TAKE
OUT GUSTS THROUGH THIS EVENING. AS MENTIONED ABOVE...WILL CONTINUE TO
MONITOR THIS AS WELL IN CASE CHANGES NEED TO BE MADE.
&&
.JKL WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...JMW
LONG TERM...SHALLENBERGER
AVIATION...JMW
AREA FORECAST DISCUSSION
NWS JACKSON KY
102 PM EST TUE DEC 17 2013
.UPDATE...
ISSUED AT 1259 PM EST TUE DEC 17 2013
THE SHORTWAVE THAT WAS ORIGINALLY SUPPOSED TO MOVE JUST TO OUR NORTH
AS OF YESTERDAY...DROPPED FURTHER SOUTH OVERNIGHT...BRINGING THE
POTENTIAL FOR HIGHER RAIN CHANCES AND SNOWFALL TOTALS ONCE
TEMPERATURES DROPPED BELOW FREEZING. GRIDS WERE UPDATED ACCORDINGLY.
HOWEVER...BASED ON LATEST HI-RES MODEL TRENDS...IN CONJUNCTION WITH
LATEST RADAR AND SATELLITE IMAGERY...ALTHOUGH THE SHORTWAVE PATTERN
REMAINS THE SAME...THE AMOUNT OF MOISTURE AND IMPACTS IS JUST MUCH
LOWER THAN ANTICIPATED. SINCE THE LATEST HRRR WAS INITIALIZING THE
BEST WITH ONGOING CONDITIONS...USED TO BLEND IN WITH THE ONGOING
FORECAST...AS WELL AS THE LATEST NAM12 AND ECMWF /ALL OF WHICH WERE
SHOWING SIMILAR LIGHTER SOLUTIONS/. WITH THIS IDEA...BEST PRECIP WILL
FALL ACROSS THE NORTHERN CWA THROUGHOUT THE EARLY AFTERNOON IN THE
FORM OF RAIN...WITH TEMPS WELL ABOVE FREEZING. BY LATER THIS
EVENING...THE SHORTWAVE WILL SHIFT SE...BRINGING BEST PRECIP CHANCES
ALONG THE FAR SERN COUNTIES NEAR THE VA AND WV BORDER. WHILE
TEMPERATURES WILL STILL SUPPORT SNOW DEVELOPMENT...THE IMPACTS WILL
BE MUCH LESS THAN ORIGINALLY CALLED FOR ON THE PREVIOUS SHIFT. ONLY A
DUSTING OR LESS IS EXPECTED IN MOST PLACES...WITH SOME OF THE HIGHER
TERRAIN POSSIBLY PICKING UP AROUND A HALF OF AN INCH OF SO. BLACK
MOUNTAIN IS FORECAST TO SEE THE HIGHEST AMOUNTS...BUT STILL ONLY
RIGHT AROUND AN INCH. SINCE UPDATES WERE MADE TO REFLECT THIS
THINKING...RADAR TRENDS CONTINUE TO SUPPORT THIS LOWERING OF QPF AND
POPS. BUT AS ALWAYS...WILL CONTINUE TO MONITOR LATEST MODEL DATA AND
ONGOING CONDITIONS IN CASE ANY UPDATES NEED TO BE MADE.
UPDATE ISSUED AT 645 AM EST TUE DEC 17 2013
A COMPLEX TEMPERATURE PATTERN REMAINS AS WE APPROACH DAWN. MANY
LOCATIONS HAVE WARMED TO THE UPPER 30S TO LOW TO MID 40S OUTSIDE OF
THE HIGH TERRAIN IN THE WARM AIR ADVECTION AHEAD OF THE APPROACHING
COLD FRONT. MEANWHILE...KI35 AND K1A6 ARE NEAR THE 30 DEGREE MARK AS
THOSE VALLEY LOCATIONS HAVE NOT BEEN SCOURED OUT. HOWEVER...THIS
FRONT IS MOVING ACROSS THE FAR NW COUNTIES AT THIS TIME AND HAS
PASSED THROUGH FFT...AND IS NEARING LEX. THIS SHOULD LEAD TO ONLY A
COUPLE OF MORE DEGREE RISE IN MANY LOCATIONS...IF THAT WITH TEMPERATURES
LIKELY REMAINING RATHER FLAT THROUGH THE MORNING AND THEN SLOWLY
TAILING OFF IN THE AFTERNOON THROUGH EARLY EVENING WITH COLD AIR
ADVECTION KICKING IN AND IN RAIN OR MIXED RAIN AND SNOW SHOWERS MOVING
THROUGH THE AREA. THE 6Z GFS BACKED AWAY A LITTLE ON THE QPF IN THE
NORTHEASTERN COUNTIES FOR THIS AFTERNOON AND THE ASSOCIATED MOS IS
SLOWER WITH THE COOLING. THESE TRENDS WILL CONTINUE TO BE MONITORED.
HOWEVER...SOME ACCUMULATION ON GRASSY AND ELEVATED SURFACES STILL
APPEARS POSSIBLE BY LATE AFTERNOON AND INTO THE EVENING AS LINGER
ISOLATED TO NUMEROUS RAIN SHOWERS CHANGE OVER TO SNOW SHOWERS.
&&
.SHORT TERM...(TODAY THROUGH WEDNESDAY)
ISSUED AT 350 AM EST TUE DEC 17 2013
THE REGION CONTINUES IN NORTHWEST FLOW ALOFT BETWEEN A RIDGE OF HIGH
PRESSURE OVER MEXICO AND EXTENDING NORTH ALONG THE US WEST COAST AND
A TROUGH EXTENDING SOUTH INTO THE GREAT LAKES...OH VALLEY REGION...AND
THE SOUTHEAST FROM A CLOSED LOW OVER ONTARIO. ONE SHORTWAVE TROUGH IS
CURRENTLY WORKING ACROSS THE OH VALLEY WITH MAINLY MID AND HIGH
CLOUDS AND VIRGA WITH ANOTHER MORE POTENT UPSTREAM SHORTWAVE WORKING
FROM MN INTO WI. AT THE SFC...AN AREA OF LOW PRESSURE IS TRACKING
INTO THE GREAT LAKES REGION WITH A TRAILING COLD FRONT EXTENDING DOWN
TO THE OH VALLEY...WHICH CROSSES NORTHEASTERN KY DOWN INTO WEST
CENTRAL KY AND ON INTO WESTERN TN ATTM. FURTHER UPSTREAM...A SFC HIGH
WAS IN PLACE ACROSS THE CENTRAL PLAINS REGION.
BANDS OF CLOUDS CONTINUE TO MOVE ACROSS THE REGION...BUT THESE ARE
MAINLY MID AND HIGH LEVEL CLOUDS SO FAR AHEAD OF A COLD FRONT.
SOUTHWEST FLOW AHEAD OF FRONT HAS BROUGHT UP INTO THE LOWER TO MID 40S
ACROSS WESTERN PARTS OF THE AREA AND ON SOME RIDGETOPS IN THE LOWER
TERRAIN...WHILE SOME LOWER 30S ARE CURRENTLY OBSERVED IN THE NON
SCOURED OUT SHELTERED VALLEYS TO THE EAST OF INTERSTATE 75 AND TO THE
SOUTH OF INTERSTATE 64.
LOW CLOUDS SHOULD MOVE BACK IN OR DEVELOP AROUND DAWN...ESPECIALLY
ACROSS NORTHERN SECTIONS BEHIND THE BOUNDARY AND LINGER INTO THE DAY
ON TUESDAY. THE COLD FRONT SHOULD NEARLY BISECT THE CWA NORTHWEST TO
SOUTHEAST AROUND DAWN...WITH THE BOUNDARY DEPARTING TO THE SOUTH OF
EASTERN KY AROUND MIDDAY.
A RATHER POTENT SHORTWAVE IS EXPECTED TO DIG INTO THE OHIO VALLEY AND
GREAT LAKES TO CENTRAL APPALACHIAN REGION ON TUESDAY. GFS 0Z MODEL
DATA INDICATES GOOD DEPTH WITH THIS SHORTWAVE AS EVIDENCED BY PV15
PRESSURE DOWN TO 550 MB AND EVEN LOWER IN THE ATMOSPHERE AS IT MOVES
INTO THE CENTRAL APPALACHIANS. WITH THIS IN MIND...HAVE OPTED TO
INCREASE POPS FROM THE INHERITED FORECAST ACROSS THE BOARD FOR
TUESDAY AFTERNOON INTO THE EVENING...AS THE WAVE MOVES THROUGH.
PRECIPITATION FOR THIS WOULD GENERALLY BE ALL RAIN INITIALLY...BUT IN
ANY CONVECTION AND DEEPER OMEGA...TEMPS WOULD HAVE THE OPPORTUNITY TO
COOL OFF ENOUGH FOR PRECIPITATION TO CHANGE OVER TO SNOW BY LATE
AFTERNOON OR EVENING...POSSIBLY AFFECTING THE EVENING COMMUTE. QPF ON
AVERAGE WITH THIS SYSTEM SHOULD GENERALLY BE A TENTH OF AN INCH OR
LESS...THOUGH LOCALLY HIGHER AMOUNTS COULD OCCUR IN ANY STRONGER
SHOWERS. INITIALLY WARM GROUND WOULD BE A LIMITING FACTOR TO ANY
ACCUMULATIONS AS WELL AS TIME OF DAY. HOWEVER...A DUSTING TO A HALF
OF AN INCH COULD CERTAINLY OCCUR ON THE RIDGETOPS ANY IN ANY LOCALLY
HEAVIER SNOW SHOWERS DURING THE LATE AFTERNOON INTO THE EVENING.
WINDS WILL ALSO BE GUSTY IN THE AFTERNOON IN THE SHOWERS...WITH 10 TO
15 MPH SUSTAINED COMMON...WITH GUSTS AROUND 25 MPH AT TIMES.
HOURLY TEMPERATURES AND MAX TEMPS FOR TUE HAVE BEEN ADJUSTED TO
ACCOUNT FOR RECENT TRENDS AND ANTICIPATED TRENDS ON TUE AS SHOWERS
MOVE THROUGH AND THE ANTICIPATED COLD AIR ADVECTION LATE IN THE DAY.
HIGH PRESSURE WILL BUILD IN AT THE SFC AND ALOFT TO END THE PERIOD...ON
WED AND DRY WEATHER IS ANTICIPATED AS THE SFC HIGH SHOULD SETTLE
ACROSS THE CENTRAL APPALACHIANS BY THE END OF THE PERIOD.
.LONG TERM...(WEDNESDAY NIGHT THROUGH MONDAY)
ISSUED AT 415 AM EST TUE DEC 17 2013
THE EXTENDED FORECAST PERIOD BEGINS ON WEDNESDAY NIGHT WITH A MAINLY
ZONAL PATTERN OVER THE CONUS BUT IN TRANSITION. AN UPPER LEVEL LOW
COMES ASHORE OVER THE SOUTHWEST AND BAJA REGION AND BECOMES CUT OFF
BUT STILL INFLUENCE BY THE UPPER LEVEL FLOW AS IT CREEPS EASTWARD.
MEANWHILE...THE NORTHERN PORTION OF THE STREAM BRINGS A SEPARATE
SHORTWAVE INTO THE PLAINS AND INTO THE MS RIVER VALLEY BY FRIDAY.
THIS WILL LEAD TO LOW DEVELOPMENT AT THE SURFACE OVER THE UPPER MS
RIVER VALLEY AS A COLD FRONT BEGINS TO PUSH INTO THE OHIO VALLEY BY
FRIDAY NIGHT. THIS FRONT BECOMES STALLED OUT THANKS TO A STAUNCH
RIDGE OVER THE ATLANTIC OCEAN. THIS HAS BECOME A POINT OF CONCERN
OVER THE PAST SEVERAL DAYS OF THE MODEL RUNS AS THIS EVENT CONTINUES
TO TAKE SHAPE.
PRECIP SHOULD BEGIN TO ENTER THE AREA ON FRIDAY AND CONTINUE THROUGH
THE WEEKEND AS THE FRONT STALLS. PLENTY OF MOISTURE IS AVAILABLE AS
THIS SYSTEM DEVELOPS BUT MOST OF THE UPPER LEVEL DYNAMICS HAVE
ALREADY PASSED OFF TO THE NORTHEAST. HOWEVER...BY SATURDAY...THE
AFOREMENTIONED CLOSED LOW OVER THE SOUTHWEST FINALLY OPENS AND EJECTS
EASTWARD INTO THE LOWER MS RIVER VALLEY. THIS WILL HELP GENERATE
RAPID CYCLOGENESIS AT THE SURFACE OVER THE SOUTHERN PLAINS ALONG THE
STALLED FRONTAL BOUNDARY AS A DEEP LOW DEVELOPS. ABUNDANT MOISTURE
WILL THEN STREAM NORTHWARD AS A WARM FRONT MOVES NORTH INTO THE
LOWER OHIO VALLEY BY SATURDAY NIGHT. THE LOW LEVEL JET SETS UP WITH
50 TO 70 KNOTS TRANSPORTING WARM AIR AND AMPLE MOISTURE NORTHWARD.
THIS WILL BRING SOAKING RAINS OVER EASTERN KENTUCKY. THE WARM FRONT
WILL MOVE NORTH INTO OHIO BY SUNDAY MORNING AS A STRONG COLD FRONT
QUICKLY HEADS EAST INTO EASTERN KENTUCKY SUNDAY AFTERNOON. HERE IN
LIES A POSSIBLE FORECAST PROBLEM AS THE FRONT MOVES EAST QUITE
QUICKLY BUT MODELS KEEP THE HIGH OVER THE ATLANTIC THAT STALLED OUT
THE PREVIOUS FRONT BARELY WEAKENED OR CENTERED ANY FARTHER EAST. THE
EURO AND GFS HAVE COME INTO AGREEMENT KEEPING THE FRONT PROGRESSIVE
AND NOW HAVE A FEW RUNS OF CONSISTENCY SO WILL KEEP THE QUICKER EXIT
BUT THIS WILL BE AN ELEMENT OF THE FORECAST TO WATCH CLOSELY. THIS
TIME OF YEAR...AND WITH THE MOISTURE THIS SYSTEM HAS TO WORK
WITH...A STALLED BOUNDARY WOULD CERTAINLY CAUSE FLOODING TO BE A
CONCERN.
THE FRONT MOVES THROUGH THE AREA BY MONDAY MORNING WITH THE COLDER
AIR ADVECTING INTO EASTERN KENTUCKY IN STRONG NORTHWEST FLOW. A WEAK
WAVE BEHIND THE FRONT WILL SLIDE SOUTHEAST BRINGING JUST ENOUGH
MOISTURE FOR SOME RAIN CHANGING TO SNOW BEHIND THE FRONT. WIND FLOW
IS ALSO JUST ABOUT FAVORABLE FOR UPSLOPE TYPE SNOWFALLS. THE DEPTH
OF MOISTURE IS IN QUESTION BEHIND THE FRONT SO ANY SNOWFALL MAY ALSO
BE SHORT IN DURATION AND CONFINED TO THE BLUEGRASS COUNTIES AS TEMPS
MAY NOT DROP OFF FAST ENOUGH BEFORE ALL THE LIST AND MOISTURE EXIT
EASTERN KENTUCKY BY MONDAY EVENING.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z WEDNESDAY AFTERNOON)
ISSUED AT 1259 PM EST TUE DEC 17 2013
LOW CIGS CONTINUE ACROSS THE NORTHER CWA AS A SHORTWAVE CONTINUES TO
MOVE ACROSS THE REGION. THIS HAS PRODUCED A LINE OF WEAK SHOWERS
MAINLY NORTH OF THE MOUNTAIN PARKWAY...POSING LITTLE THREAT TO VIS.
THE ONLY TAF SITE WHICH MAY POSSIBLY BE IMPACTED BY THIS RAIN IS
KSJS...BUT IMPACTS WILL BE MINIMAL. AS WE CONTINUE THROUGHOUT THE
EVENING...EXPECT THE SHORTWAVE TO SHIFT SE...BRINGING INCREASING POPS
TO THE FAR SE COUNTIES...MAINLY ALONG THE VA AND WV BORDER. AS
TEMPERATURES FALL THROUGHOUT THE EVENING...THIS PRECIPITATION WILL
CHANGE OVER TO SNOW. BUT ONCE AGAIN...THE ONLY TAF SITE WHICH SHOULD
FEEL ANY IMPACTS FROM THIS WILL BE KSJS. DROPPED THE CIGS AT KSJS TO
MVFR AS THE PRECIPITATION MOVES THROUGH...BEFORE CLEARING OUT LATE
TONIGHT AS HIGH PRESSURE MOVES IN OVERHEAD. FOR THE REMAINING TAF
SITES...SOME LOW CLOUDS MAY BE FELT LATER IN THE EVENING AS THE
SHORTWAVE MOVES SE ACROSS THE AREA. HOWEVER...BASED ON LATEST NAM12
AND GFSLAMP DATA...THESE CLOUDS SHOULD STAY RIGHT AT OR SLIGHTLY
ABOVE THE VFR RANGE...BEFORE CLEARING OUT LATE TONIGHT.
AS FAR AS WINDS...HIGH PRESSURE GRADIENTS ACROSS THE REGION TODAY AND
THIS EVENING SHOULD LEAD TO SOME POSSIBLE GUSTS IN THE 15 TO 20KT
RANGE. UNFORTUNATELY...RECENT OBSERVATIONS HAVE NOT SHOWN THIS
MATERIALIZING AS WELL...THOUGH THE POTENTIAL IS MOST CERTAINLY
STILL THERE. WENT AHEAD AND KEPT WINDS AT 10KTS OR SO...BUT DID TAKE
OUT GUSTS THROUGH THIS EVENING. AS MENTIONED ABOVE...WILL CONTINUE TO
MONITOR THIS AS WELL IN CASE CHANGES NEED TO BE MADE.
&&
.JKL WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...JMW
SHORT TERM...JP
LONG TERM...SHALLENBERGER
AVIATION...JMW
AREA FORECAST DISCUSSION
NWS LOUISVILLE KY
959 PM EST Mon Dec 16 2013
...Forecast Update...
Issued at 958 PM EST Mon Dec 16 2013
Made a few updates to the overnight forecast. The clipper system to
our north continues to track across the Great Lakes, with clouds on
the increase across the forecast area. A few radar returns across
our northern CWA are tracking east-southeast and may contain a few
flurries. So, have added this to the forecast for a few hours,
tracking from southeast IN into the northern Blue Grass region of
KY. Otherwise, the surface front, as noted in the short-term
forecast discussion, will settle just south of the Ohio River
overnight. Low-level moisture below about 2Kft will accompany this
boundary. All signs point to low clouds building in around or
shortly after 4 AM EST and lingering through daybreak, coincident
with the front. Not expecting precip with this boundary given the
very shallow/thin moisture, but cannot rule out some very light,
patchy drizzle. The rest of the forecast remains on track.
.SHORT TERM (Now through Tuesday Night)...
Issued at 257 PM EST Mon Dec 16 2013
A tight temperature gradient, augmented by differences in snowpack,
currently lies across southern Indiana. At 2 pm, temperatures ranged
from 45 at Louisville to 24 degrees at Indianapolis. Low clouds and
light fog will continue right along a line from Dubois through
Jefferson County, Indiana.
Farther south, clear skies and mild temperatures will continue
through this evening, as light southwest winds continue.
The synoptic pattern across the CONUS features a broad longwave
500mb trough over the Great Lakes. Two weak shortwaves will move
across Indiana over the next couple of days. The first will push a
weak cold front south of the Ohio River this evening and overnight.
No precipitation is expected with no mid-level moisture. However,
winds will shift to the west overnight, and temperatures will lower
a few degrees from our lows earlier this morning.
The second front will move across during the day Tuesday. A tight
pressure gradient will develop during the afternoon as high
pressure builds south across Kansas. West winds will pick up
during the afternoon and peak around 15 mph with some gusts over
25 mph.
Clouds will increase by late this evening as cooler air filters
in. Expect that cloudy skies will continue through the morning
hours Tuesday, especially north of Interstate 64. Lows tonight
will range from the upper 20s north to the lower 30s towards
Tennessee.
Tuesday will remain cooler than earlier this afternoon, even over
our southern counties, with highs ranging from the mid 30s to the
mid 40s. High pressure will build east over Tennessee Tuesday
night. Expect mostly clear skies and lows from the upper 20s to
the lower 30s.
.LONG TERM (Wednesday through Monday)...
Issued at 250 PM EST Mon Dec 16 2013
A couple of noticeable pattern changes are on the way for the
extended forecast. The first will come as the persistent upper
trough over our region flattens out and allows warmer temperatures
into the region. High temperatures have been below normal at SDF
since the snowfall of 12/6, and they should flip back above by
Wednesday with highs going up into the 60s possibly by Friday. This
warm air will come from a southerly flow that becomes established as
high pressure to our southwest makes it way east of the area
Thursday.
The next pattern change will come from an upper low currently along
the Alaskan coast. A piece of this energy will drop to the southern
California coast and stall for a bit. Despite apparent unity among
the deterministic models on this forecast, ensemble spreads still
show a bit of uncertainty. Still the rough location of this feature
will tilt the flow aloft over us to southwesterly, which should
increase our moisture. Combined with a cold front forecast to move
in Friday with a northern stream trough will mean a good shot at
rain.
That front still looks to stall somewhere in the area for the
weekend and with continued southwesterly flow will mean good rain
chances likely through the weekend. As with the agreement on what
the upper low will do Friday, the GFS/GEM/Euro also are in
general agreement with that low opening up and moving into the
southern Plains Sunday. In response a surface low should develop
along the stalled frontal boundary. As with any system this far out,
there will be timing/location differences for several model runs to
come on where this surface low tracks/how deep it gets. Thus we have
a low confidence forecast in temps and potentially precip type over
our northern forecast area.
Will keep in good rain chances through the weekend, and then leave
in lesser chances for Monday, with the upper trough passage.
Rainfall totals from Thursday night through Sunday night with this
package will range from 2.5-3.5 inches across the region. Depending
on how quick this rain comes at any one time, we may see some water
issues, and will keep that wording in our HWO. In addition, should
the deepening low track close to our area, we will have to watch for
severe weather potential as well. Stay tuned.
&&
.HYDROLOGY...
Issued at 300 PM EST Mon Dec 16 2013
A winter storm will move across the Ohio Valley this weekend. A cold
front will stall and a series low pressure systems will move along
the front. Several waves of precipitation will begin Thursday night
and continue through Sunday. In southern Indiana and Kentucky these
systems are forecast to bring a large amount of rain. This area is
recovering from heavy rain and snowmelt from the previous storm so
the rivers and streams will respond faster and rise higher than
during the previous storm. More specific forecasts will be released
as the event comes clearer.
&&
.AVIATION (00Z TAF Update)...
Updated at 630 PM EST Mon Dec 16 2013
All sites are reporting VFR conditions, which should hold a little
longer this evening before clouds build back across the region, as a
clipper system tracks southeast through the Great Lakes tonight.
Ceilings will be a low confidence forecast for SDF and LEX. Guidance
has backed off a bit on MVFR cigs overnight and upstream obs are no
help either, with the low cigs across IL occurring over the snow
pack. However, given the latest RAP analysis and low-level moisture
still depicted in the soundings and time heights, will go with MVFR
ceilings at SDF and LEX overnight and into mid morning Tuesday
before improving. The RAP indicates IFR conditions and if the very
moist low-level profile pans out, this could be correct. Not
confident enough to go that low just yet. Confidence is lower that
ceilings will drop to MVFR at BWG, thus will keep conditions VFR
through the overnight period. Expect light winds tonight but they
will pick up out of the west Tuesday, increasing to around 10-15
knots with a few gusts of 20-25 knots during the afternoon.
&&
.LMK WATCHES/WARNINGS/ADVISORIES...
KY...NONE.
IN...NONE.
&&
$$
Update.........MJP
Short Term.....JSD
Long Term......RJS
Hydrology......CMC
Aviation.......MJP
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
457 PM EST TUE DEC 17 2013
.SHORT TERM...(THIS EVENING THROUGH WEDNESDAY)
ISSUED AT 343 PM EST TUE DEC 17 2013
NOTE THAT TEMPS AT CMX REMAIN QUESTIONABLE DUE TO FAULTY FAN ON
OBSERVATION EQUIPMENT. TECHNICIANS WL BE WORKING ON THIS PROBLEM
TMRW.
12Z RAOBS/LATEST WV IMAGERY AND RUC ANALYSIS SHOW PERSISTENT NW FLOW
ALF BTWN DEEP UPR TROF CENTERED OVER ONTARIO AND UPR RDG OVER WRN
NAMERICA. H5 TEMPS WITHIN THE TROF EXTENDING INTO THE GREAT LKS ARE
AS LO AS -40C...SO THE AREA REMAINS IN THE GRIP OF WINTER CHILL. ONE
SHRTWV EMBEDDED WITHIN THE UPR TROF BROUGHT SOME -SN TO THE SCNTRL
CWA THIS MRNG...BUT THIS DISTURBANCE/DEEPER MSTR SHOWN ON THE 12Z
GRB RAOB HAVE SHIFTED TO THE E. ANOTHER SHRTWV IS PRESENT OVER MN...
BUT THIS DISTURBANCE WL BE PASSING TOO FAR TO THE S TO HAVE AN
IMPACT ON UPR MI. YET ANOTHER SHRTWV IS OVER NW ONTARIO AND DROPPING
SEWD. ATTENDANT SFC-H85 COLD FNT MOVED INTO WRN UPR MI THIS AFTN.
12Z INL/YPL RAOBS SHOW HI RELATIVE RH TO H6-5 AND 12Z H85 TEMPS
RANGING FM -13C AT INL RIGHT BEHIND THE COLD FNT TO -24C AT YPL...
WHICH WAS DEEPER INTO THE COLD AIRMASS. SO THERE ARE POCKETS OF SHSN
EXTENDING UPWIND OF LK SUP IN NRN MN/ADJOINING ONTARIO. FARTHER TO
THE W...THERE ARE SIGNS THE FLOW IS BECOMING A BIT MORE
PROGRESSIVE...AT LEAST FOR A SHORT TIME. 00Z-12Z H3 HGT RISES UP TO
150M WERE REPORTED AT SEVERAL UPR AIR SITES FM THE NRN PLAINS INTO
SCNTRL CANADA AS THE WRN RDG SHIFTS TO THE E.
MAIN FCST CONCERNS IN THE SHORT TERM FOCUS ON LES POPS/AMOUNTS WITH
ARRIVAL OF MORE ARCTIC AIR BEHIND EARLY AFTN/EARLY EVNG COLD FROPA.
TNGT...SHRTWV IN NW ONTARIO IS FCST TO SHIFT SEWD ACRS NRN LK SUP...
ACCOMPANIED BY AREA OF WEAK H85-5 QVECTOR CNVGC/SOME DEEPER MSTR AND
ATTENDANT COLD FROPA. EXPECT SHSN INTENSITY/COVERAGE TO INCRS LATE
THIS AFTN/EVNG W-E...ESPECIALLY IN AREAS NEAR LK SUP FAVORED BY THE
WNW FLOW IN THE WAKE OF THE COLD FROPA...WHICH WL BE FOLLOWED BY
AXIS OF H85 TEMPS AS LO AS -20C. ALTHOUGH NOT OUT OF THE QUESTION
THERE COULD BE SOME HEAVIER SHSN IN THE FAVORED SN BELTS...ADVY SN
SEEMS UNLIKELY. THE FIRST LIMITING FACTOR WL BE RELATIVELY SHORT
DURATION OF THE HEAVIER LES. HGT RISES NOTED IN THE NRN PLAINS/
SCENTRAL CANADA ARE PROGGED TO FOLLOW QUICKLY THE DEPARTING SHRTWV
LATER IN THE EVNG WITH VIGOUROUS DNVA/DEEP LYR QVECTOR DVGC LOWERING
SUBSIDENCE INVRN TO NEAR 3K FT OVER THE KEWEENAW BY 12Z. APRCH OF
SFC RDG AXIS AND SHIFTING LLVL WINDS OVER THE W UNDER THESE NEGATIVE
DYNAMICS...WITH RDG AXIS ARRIVING THERE BY 12Z...WL ALSO ACT TO
SUPPRESS THE SN AMOUNTS. IN FACT...SUITE OF HIER RES MODEL OUTPUT IS
QUITE VARIABLE ON QPF...WITH FCSTS INCONSISTENT ON MAGNITUDE/HGT/
TIMING OF SHARPER UVV AND RELATIVE TO THE DGZ. IN THE NW WIND SN
BELTS TO THE E OF MQT...SHSN WL ARRIVE DURING THE EVNG AND PERSIST
THRU 12Z. LONGER FETCH OVER THE OPEN WATER WL PLAY AN ENHANCEMENT
ROLE IN INTENSIFYING THE SHSN STREAMING INTO THIS AREA...BUT
SHIFTING WINDS MAY LIMIT THE RESIDENCE TIME OF THE HEAVIER SHSN HERE
AS WELL. THE MOST FAVORABLE FACTOR FOR HEAVIER SN OVER THE ERN CWA
NEAR LK SUP WL BE THE POTENTIAL FOR LAND BREEZE CNVGC OVER FAR
EASTERN ALGER/NRN LUCE COUNTIES. BUT FCST SDNGS SHOW SUBSIDENCE
INVRN SINKING FAIRLY STEADY HERE AS WELL LATER AT NGT WHEN THE
POTENTIAL FOR THE SHARPER LLVL CNVGC WOULD BE GREATER. AS IS
TYPICAL...AREAS OVER THE SCENTRAL WL SEE NOTHING MORE THAN ISOLD
-SHSN WITH DOWNSLOPE FLOW. EXPECT THE LOWEST MIN TEMPS OVER THE
INTERIOR W...WHERE THERE WL BE SOME CLRG/LIGHT WINDS WITH ARRIVAL OF
SFC RDG AXIS.
WED...AS THE UPR FLOW TENDS TO SHIFT MORE ZONAL...A SHRTWV IS FCST
TO SHIFT E THRU SCENTRAL CANADA...WITH ASSOCIATED SFC LO PRES FCST
TO MOVE INTO NRN MN BY 00Z THU. GENERAL WAD/ISENTROPIC LIFT BTWN
THIS SHRTWV/SFC LO AND SFC HI SHIFTING INTO THE SE CONUS WL IMPACT
THE UPR GRT LKS. AS THE FLOW BACKS TO THE SW...LINGERING LES OVER
THE KEWEENAW AND FAR E CWA NEAR LK SUP WL SHIFT OUT INTO THE OPEN
LK. THE BULK OF THE MODELS SHOW LGT SN ASSOCIATED WITH THE SHARPER
ISENTROPIC ASCENT FALLING OVER LK SUP. THE CNDN MODEL IS THE ONE
EXCEPTION...AS THIS MODEL SHOWS THE SFC LO A BIT FARTHER S IN MN AND
STRIPE OF LGT -SN IMPACTING APPROXIMATELY THE NE HALF OF THE CWA.
GIVEN PERSISTENCE OF TROF IN ERN CANADA AND CHILL...SUSPECT THIS
MODEL IS ON THE RIGHT TRACK. SO WL SHIFT THE AXIS OF CHC POPS A BIT
TO THE SW INTO THE NRN LAND CWA. FEED OF RELATIVELY DRY LLVL AIR WL
LIMIT ANY POTENTIAL SN ACCUM EVEN IF THE MORE PESSIMISTIC CNDN MODEL
DOES VERIFY. ALSO LOWERED FCST MAX TEMPS A BIT TO REFLECT THE
POTENTIAL FOR MORE TENACIOUS COLD LLVL AIR.
.LONG TERM...(WEDNESDAY NIGHT THROUGH TUESDAY)
ISSUED AT 457 PM EST TUE DEC 17 2013
MUCH OF THIS FCST PERIOD IS IN THE MODERATE TO LOWER CONFIDENCE
RANGE.
AT 00Z THURSDAY MUCH OF THE CONTINENTAL U.S. WILL BE UNDER A BROAD
WEAK RIDGE TO ZONAL FLOW AT 500MB...WITH THE DOMINANT LOW SPINNING
ACROSS N CANADA WITH LONGWAVE TROUGHS EXTENDING ACROSS BOTH THE WEST
AND EAST COASTS.
AN INITIAL BROAD SFC LOW/TROUGH WILL EXTEND NE INTO CENTRAL LAKE
SUPERIOR AT 00Z. WHILE THE GFS PUSHES THE LOW E OF LAKE SUPERIOR BY
06Z THURSDAY...THE ECMWF KEEPS IT AS PART OF THE MAIN SYSTEM TO OUR
S. THE RESULT IS A COMPLETELY DIFFERENT FCST FOR WEDNESDAY
NIGHT...WITH LES OFF THE GFS ON STRONGER NW WINDS...WHILE THE ECMWF
SOLUTION KEEPS A WAA SCHEME OVER THE AREA A BIT LONGER. THEY BOTH DO
AGREE WITH SOME SORT OF LAKE ENHANCEMENT N OR NW FLOW BY THURSDAY
AFTERNOON...ALTHOUGH THE GFS IS APPROX 2C COOLER NEAR THE SFC.
LOOK FOR THE CANADIAN AND W COAST SYSTEMS TO DEEPEN AS THEY SINK SSE
THURSDAY AND FRIDAY. AT 18Z THURSDAY THE MAIN TROUGH WILL EXTEND
FROM THE S LOW OVER S CA UP THROUGH MT INTO S CANADA.
A QUICK BURST OF SNOW THURSDAY NIGHT LOOKS TO BE ABOUT IT...EXCEPT
FOR SOME LAKE EFFECT/LAKE ENHANCEMENT ON W TO NW WINDS OVER THE
KEWEENAW PENINSULA...AND AROUND AND E OF MUNISING THROUGH ABOUT MID
MORNING FRIDAY. TOTAL SNOWFALL OF 1-2IN STILL LOOK GOOD. CONFIDENCE
REMAINS LOW WITH THIS SYSTEM. THE 12Z NAM DID NOT REALLY BRING ANY
OF THE SYNOPTIC MOISTURE INTO UPPER MI...ALTHOUGH THE 18Z VERSION
BROUGHT SNOW BACK NW SIMILARLY TO THE GFS. WILL STILL HIGHLIGHT THE
POTENTIAL FOR A FEW INCHES OF SNOW LATE THURSDAY AFTERNOON INTO
FRIDAY MORNING...MAINLY OVER THE HIGHER TERRAIN NEAR LAKE SUPERIOR.
THE NEXT LOW OVER THE ROCKIES SATURDAY WILL EJECT NE SUNDAY...WITH
UPPER MI AGAIN ON THE BACK SIDE OF THE LOW. GIVEN THE STRENGTH OF
THE SYSTEM...AND SIGNIFICANT HIGH DROPPING IN FROM THE NW SUNDAY
THROUGH MONDAY...MUCH COLDER AIR WILL BE ABLE TO SLIDE IN. 850MB
TEMPS OF -20 TO -22C WILL BE POSSIBLE. THERE ARE SOME TIMING
DIFFERENCES BETWEEN THE GFS AND ECMWF AT THIS PERIOD...BUT THEY ARE
CONSISTENT WITH THE COLD AIR.
FARTHER OUT...EXPECT STRONG WAA TUESDAY BEHIND THE COLD AIRMASS.
WHILE TIMING IS STILL IN QUESTION...SW 40-55KT 850MB WINDS WITH SFC
WINDS OF 15-25KTS LOOK LIKELY FOR A 6HR WINDOW BETWEEN 09Z TUESDAY
TO 00Z WEDNESDAY. WILL NEED TO MONITOR MODEL TRENDS TO ADD MORE
SPECIFICITY AS THE TIME NEARS.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z WEDNESDAY AFTERNOON)
ISSUED AT 1225 PM EST TUE DEC 17 2013
AS A COLD FNT/AREA OF DEEPER MSTR SURGE ACROSS UPR MI THIS AFTN/
EVNG...EXPECT A PERIOD OF IFR CONDITIONS TO IMPACT IWD AND
ESPECIALLY CMX...WHERE SHARPER UPSLOPE WIND COMPONENT/GREAT EXPOSURE
TO FCST WNW WIND WL ENHANCE THE SHSN/BLSN AND POTENTIAL FOR LOWER
CIGS. SAW MAY SEE MVFR CONDITIONS WITH A DOWNSLOPE WIND COMPONENT
LIMITING THE POTENTIAL FOR LOWER CONDITIONS. THE APRCH OF A HI PRES
RDG AXIS/DRIER AIR LATER TNGT WL CAUSE IMPROVING WX...WITH
CONDITIONS IMPROVING TO VFR LATER TNGT W-E FOLLOWING THE PASSAGE OF
RDG AXIS WSHFT TO THE SW. A MORE PERSISTENT UPSLOPE WIND COMPONENT
WL SLOW THE IMPROVEMENT AT CMX.
&&
.MARINE...(FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 343 PM EST TUE DEC 17 2013
EXPECT NW WINDS TO 25-30 KTS THIS EVENING BEHIND A COLD FRONTAL
PASSAGE TO DIMINISH AND BACK TO THE SW WITH APPROACH OF A HI PRES
RIDGE LATER TONIGHT INTO WED. A VERY CHANGEABLE WEATHER PATTERN WILL
THEN DOMINATE THE UPPER GREAT LAKES THE REST OF THE WEEK...WITH HARD
TO TIME DISTURBANCES IMPACTING LAKE SUPERIOR. CONFIDENCE IS LOW IN
TIMING THESE DISTURBANCES AND ACCOMPANYING WIND SHIFTS...BUT GALES
APPEAR UNLIKELY THRU THE FORECAST PERIOD.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
NONE.
LAKE MICHIGAN...
NONE.
&&
$$
SHORT TERM...KC
LONG TERM...KF
AVIATION...KC
MARINE...KC
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
344 PM EST TUE DEC 17 2013
.SHORT TERM...(THIS EVENING THROUGH WEDNESDAY)
ISSUED AT 343 PM EST TUE DEC 17 2013
NOTE THAT TEMPS AT CMX REMAIN QUESTIONABLE DUE TO FAULTY FAN ON
OBSERVATION EQUIPMENT. TECHNICIANS WL BE WORKING ON THIS PROBLEM
TMRW.
12Z RAOBS/LATEST WV IMAGERY AND RUC ANALYSIS SHOW PERSISTENT NW FLOW
ALF BTWN DEEP UPR TROF CENTERED OVER ONTARIO AND UPR RDG OVER WRN
NAMERICA. H5 TEMPS WITHIN THE TROF EXTENDING INTO THE GREAT LKS ARE
AS LO AS -40C...SO THE AREA REMAINS IN THE GRIP OF WINTER CHILL. ONE
SHRTWV EMBEDDED WITHIN THE UPR TROF BROUGHT SOME -SN TO THE SCNTRL
CWA THIS MRNG...BUT THIS DISTURBANCE/DEEPER MSTR SHOWN ON THE 12Z
GRB RAOB HAVE SHIFTED TO THE E. ANOTHER SHRTWV IS PRESENT OVER MN...
BUT THIS DISTURBANCE WL BE PASSING TOO FAR TO THE S TO HAVE AN
IMPACT ON UPR MI. YET ANOTHER SHRTWV IS OVER NW ONTARIO AND DROPPING
SEWD. ATTENDANT SFC-H85 COLD FNT MOVED INTO WRN UPR MI THIS AFTN.
12Z INL/YPL RAOBS SHOW HI RELATIVE RH TO H6-5 AND 12Z H85 TEMPS
RANGING FM -13C AT INL RIGHT BEHIND THE COLD FNT TO -24C AT YPL...
WHICH WAS DEEPER INTO THE COLD AIRMASS. SO THERE ARE POCKETS OF SHSN
EXTENDING UPWIND OF LK SUP IN NRN MN/ADJOINING ONTARIO. FARTHER TO
THE W...THERE ARE SIGNS THE FLOW IS BECOMING A BIT MORE
PROGRESSIVE...AT LEAST FOR A SHORT TIME. 00Z-12Z H3 HGT RISES UP TO
150M WERE REPORTED AT SEVERAL UPR AIR SITES FM THE NRN PLAINS INTO
SCNTRL CANADA AS THE WRN RDG SHIFTS TO THE E.
MAIN FCST CONCERNS IN THE SHORT TERM FOCUS ON LES POPS/AMOUNTS WITH
ARRIVAL OF MORE ARCTIC AIR BEHIND EARLY AFTN/EARLY EVNG COLD FROPA.
TNGT...SHRTWV IN NW ONTARIO IS FCST TO SHIFT SEWD ACRS NRN LK SUP...
ACCOMPANIED BY AREA OF WEAK H85-5 QVECTOR CNVGC/SOME DEEPER MSTR AND
ATTENDANT COLD FROPA. EXPECT SHSN INTENSITY/COVERAGE TO INCRS LATE
THIS AFTN/EVNG W-E...ESPECIALLY IN AREAS NEAR LK SUP FAVORED BY THE
WNW FLOW IN THE WAKE OF THE COLD FROPA...WHICH WL BE FOLLOWED BY
AXIS OF H85 TEMPS AS LO AS -20C. ALTHOUGH NOT OUT OF THE QUESTION
THERE COULD BE SOME HEAVIER SHSN IN THE FAVORED SN BELTS...ADVY SN
SEEMS UNLIKELY. THE FIRST LIMITING FACTOR WL BE RELATIVELY SHORT
DURATION OF THE HEAVIER LES. HGT RISES NOTED IN THE NRN PLAINS/
SCENTRAL CANADA ARE PROGGED TO FOLLOW QUICKLY THE DEPARTING SHRTWV
LATER IN THE EVNG WITH VIGOUROUS DNVA/DEEP LYR QVECTOR DVGC LOWERING
SUBSIDENCE INVRN TO NEAR 3K FT OVER THE KEWEENAW BY 12Z. APRCH OF
SFC RDG AXIS AND SHIFTING LLVL WINDS OVER THE W UNDER THESE NEGATIVE
DYNAMICS...WITH RDG AXIS ARRIVING THERE BY 12Z...WL ALSO ACT TO
SUPPRESS THE SN AMOUNTS. IN FACT...SUITE OF HIER RES MODEL OUTPUT IS
QUITE VARIABLE ON QPF...WITH FCSTS INCONSISTENT ON MAGNITUDE/HGT/
TIMING OF SHARPER UVV AND RELATIVE TO THE DGZ. IN THE NW WIND SN
BELTS TO THE E OF MQT...SHSN WL ARRIVE DURING THE EVNG AND PERSIST
THRU 12Z. LONGER FETCH OVER THE OPEN WATER WL PLAY AN ENHANCEMENT
ROLE IN INTENSIFYING THE SHSN STREAMING INTO THIS AREA...BUT
SHIFTING WINDS MAY LIMIT THE RESIDENCE TIME OF THE HEAVIER SHSN HERE
AS WELL. THE MOST FAVORABLE FACTOR FOR HEAVIER SN OVER THE ERN CWA
NEAR LK SUP WL BE THE POTENTIAL FOR LAND BREEZE CNVGC OVER FAR
EASTERN ALGER/NRN LUCE COUNTIES. BUT FCST SDNGS SHOW SUBSIDENCE
INVRN SINKING FAIRLY STEADY HERE AS WELL LATER AT NGT WHEN THE
POTENTIAL FOR THE SHARPER LLVL CNVGC WOULD BE GREATER. AS IS
TYPICAL...AREAS OVER THE SCENTRAL WL SEE NOTHING MORE THAN ISOLD
-SHSN WITH DOWNSLOPE FLOW. EXPECT THE LOWEST MIN TEMPS OVER THE
INTERIOR W...WHERE THERE WL BE SOME CLRG/LIGHT WINDS WITH ARRIVAL OF
SFC RDG AXIS.
WED...AS THE UPR FLOW TENDS TO SHIFT MORE ZONAL...A SHRTWV IS FCST
TO SHIFT E THRU SCENTRAL CANADA...WITH ASSOCIATED SFC LO PRES FCST
TO MOVE INTO NRN MN BY 00Z THU. GENERAL WAD/ISENTROPIC LIFT BTWN
THIS SHRTWV/SFC LO AND SFC HI SHIFTING INTO THE SE CONUS WL IMPACT
THE UPR GRT LKS. AS THE FLOW BACKS TO THE SW...LINGERING LES OVER
THE KEWEENAW AND FAR E CWA NEAR LK SUP WL SHIFT OUT INTO THE OPEN
LK. THE BULK OF THE MODELS SHOW LGT SN ASSOCIATED WITH THE SHARPER
ISENTROPIC ASCENT FALLING OVER LK SUP. THE CNDN MODEL IS THE ONE
EXCEPTION...AS THIS MODEL SHOWS THE SFC LO A BIT FARTHER S IN MN AND
STRIPE OF LGT -SN IMPACTING APPROXIMATELY THE NE HALF OF THE CWA.
GIVEN PERSISTENCE OF TROF IN ERN CANADA AND CHILL...SUSPECT THIS
MODEL IS ON THE RIGHT TRACK. SO WL SHIFT THE AXIS OF CHC POPS A BIT
TO THE SW INTO THE NRN LAND CWA. FEED OF RELATIVELY DRY LLVL AIR WL
LIMIT ANY POTENTIAL SN ACCUM EVEN IF THE MORE PESSIMISTIC CNDN MODEL
DOES VERIFY. ALSO LOWERED FCST MAX TEMPS A BIT TO REFLECT THE
POTENTIAL FOR MORE TENACIOUS COLD LLVL AIR.
.LONG TERM...(WEDNESDAY THROUGH MONDAY)
ISSUED AT 355 AM EST TUE DEC 17 2013
OVERALL...THE GENERAL IDEA OF THE LONG TERM PERIOD IS SIMILAR TO
WHAT WAS SEEN 24 HOURS AGO.
TO START THE PERIOD WEDNESDAY MORNING...LAKE EFFECT SNOW WILL BE
ONGOING OVER CENTRAL AND EASTERN LAKE SUPERIOR...WITH THE MAIN
AREAS SEEING SNOW BEING THE KEWEENAW PENINSULA AND AREAS EAST OF
MUNISING NEAR LAKE SUPERIOR. BUT WITH A HIGH PRESSURE RIDGE SLIDING
ACROSS SOUTHERN UPPER MICHIGAN...WINDS WILL BE BACKING TO THE
SOUTHWEST THROUGH THE MORNING AND PUSH THE LINGERING BANDS OFF
SHORE. IN ADDITION...SUBSIDENCE ASSOCIATED WITH THE HIGH WILL BE
LOWERING THE INVERSION HEIGHTS BELOW 4KFT BY 18Z AND ALSO HELP TO
BRING AN END TO THE SNOW IN THE U.P. ATTENTION THEN TURNS TO
SHORTWAVE RUNNING ALONG THE US/CANADIAN BORDER ON WEDNESDAY
AFTERNOON AND THE ASSOCIATED WEAK SURFACE LOW OR TROUGH THAT
FOLLOWS A SIMILAR PATH. THE FARTHER NORTH IDEA SEEN YESTERDAY SEEMS
TO BE HOLDING TRUE WITH THE 00Z RUNS TODAY (AND HAS EVEN TRENDED A
LITTLE FARTHER NORTHEAST)...WHICH WILL LIKELY LIMIT PRECIPITATION
CHANCES OVER MUCH OF UPPER MICHIGAN WEDNESDAY AFTERNOON/EVENING.
BEST DEEP MOISTURE WILL BE OVER THE NORTHERN PORTIONS OF LAKE
SUPERIOR WHERE THE SHORTWAVE TRACKS...WHILE DRY AIR IN THE LOWER
LEVELS LINGERING FROM THE DEPARTING SURFACE RIDGE WILL LIKELY LIMIT
PRECIPITATION OVER THE SOUTHERN PORTIONS OF UPPER MICHIGAN. GOING
FORECAST HAD A FAIRLY GOOD HANDLE ON THIS (CHANCES OVER LAKE
SUPERIOR AND THE KEWEENAW) BUT PUSHED THE SLIGHTS FARTHER NORTH
AND CLOSER TO LAKE SUPERIOR.
UNCERTAINTY GROWS FOR LATER WEDNESDAY NIGHT INTO THURSDAY...AS
MODELS ARE CONTINUING TO STRUGGLE WITH THE SURFACE TROUGH AND
EASTWARD EXTENT OF THE SURFACE RIDGE STRETCHING INTO ONTARIO. THE
SURFACE TROUGH WILL LIKELY SHIFT SOUTHEAST OF THE CWA SOMETIME LATE
WEDNESDAY NIGHT INTO THURSDAY...WHICH WILL GRADUALLY SHIFT WINDS TO
MORE OF A NORTHERLY OR NORTH-NORTHEAST DIRECTION. THE TIMING OF
THIS TRANSITION WILL DETERMINE PRECIPITATION TIMING AS COLDER AIR
(900-850MB TEMPS FALLING TO -13C) MOVES SOUTH OVER THE NW HALF OF
THE CWA. THIS COLDER AIR IS VERY SHALLOW (INVERSION HEIGHTS AT 850MB
OR 3-5KFT) SO SNOW SHOWER STRENGTH SHOULD BE LIMITED. THUS...WILL
CONTINUE LOW CHANCE POPS OVER THE NORTHWEST HALF OF THE CWA FOR
THURSDAY MORNING AND THEN SPREAD IT INTO NORTH CENTRAL AND PARTS OF
NORTHEAST UPPER MICHIGAN IN THE AFTERNOON.
THURSDAY NIGHT/S WEATHER IS DEPENDENT ON A LOW DEVELOPING ON THE
TROUGH IN THE MID MISSISSIPPI VALLEY AND THEN TRACKING NORTHEAST
THROUGH LOWER MICHIGAN ON THURSDAY NIGHT. MODELS STILL DIFFERING ON
THE EXACT TRACK OF THE LOW...BUT 00Z MODEL DETERMINISTIC RUNS
AND ENSEMBLE MEMBERS SEEM TO BE CENTERING ON CENTRAL TO SOUTHERN
LOWER MICHIGAN (PROBABLY TRACKING THROUGH OR SOUTH OF SAGINAW BAY
AFTER MIDNIGHT THURSDAY NIGHT). WHILE THE LOW ISN/T IN THE MOST
FAVORABLE POSITION OF THE RIGHT REAR OF THE UPPER JET AND NORTHERN
STREAM SHORTWAVE...THE UPPER GREAT LAKES IS. THUS...EXPECT THE
PRECIPITATION TO BE FARTHER NORTHWEST FROM THE LOW AND
INFLUENCING A GOOD PORTION OF THE CWA. ONE LARGER SCALE ITEM TO KEEP
AN EYE ON IS THE ECMWF/S INSISTENCE ON A THIN STREAK OF ENHANCED MID
LEVEL FGEN SLIDING ACROSS UPPER MICHIGAN. SINCE THE LOW LEVEL FLOW
WILL BE OUT OF THE NORTHERLY DIRECTION AND TEMPERATURES WILL BE COLD
ENOUGH FOR LAKE ENHANCEMENT (850MB TEMPS AROUND -13C) OVER THE
NORTHERN PART OF THE U.P. WILL CONTINUE TO SHOW HIGH CHANCE AND LOW
LIKELY POPS ACROSS THE AREA...WITH THE HIGHEST VALUES IN THE NORTH
WIND FAVORED LOCATIONS. CONFIDENCE IS A LITTLE LOWER ON WIDESPREAD
ADVISORY SNOWFALL AND MOST AREAS WILL PROBABLY ONLY SEE 2-3IN OF
SNOW...ALTHOUGH LAKE ENHANCED AREAS MIGHT REACH THE 3-4IN ADVISORY
VALUES. ON THE BACK SIDE OF THE LOW...MODELS CONTINUE TO SHOW
SIGNIFICANT DRYING AND A QUICK END TO ANY LAKE ENHANCEMENT. OPTED
TO SHOW A FASTER DIMINISHING TREND THROUGH THE DAY FRIDAY IN THE
LAKE ENHANCED AREAS AS HIGH PRESSURE QUICKLY BUILDS IN.
THIS HIGH WILL BE SHORT LIVED AS A WEAK SHORTWAVE SLIDES ACROSS THE
UPPER GREAT LAKES LATE FRIDAY NIGHT AND INTO SATURDAY. HAVE TRENDED
POPS UP SLIGHTLY AND THEY MAY NEED TO BE ADJUSTED UP FURTHER IF
MODELS CONTINUE TO INDICATE A QUICK DUSTING OF SNOW.
FOR THE REST OF THE WEEKEND...AREA WILL REMAIN ON THE EASTERN
SIDE OF A BROAD UPPER TROUGH OVER THE CENTRAL CONUS...WITH A
BULK OF THE ENERGY AROUND NEW MEXICO AND TEXAS. THE DISTURBANCE NEAR
TEXAS WILL SHIFT NORTHEAST ON SUNDAY WHILE A NORTHERN STREAM WAVE
DROPS SOUTHEAST TOWARDS THE UPPER GREAT LAKES. THE MAIN LOW
ASSOCIATED WITH THIS ENERGY WILL MOVE THROUGH OR JUST NORTH OF THE
OHIO RIVER VALLEY WHILE HIGH PRESSURE IN SASKATCHEWAN ON SATURDAY
WILL MOVE SOUTHEAST ON SUNDAY AND OVER THE UPPER GREAT LAKES REGION
FOR MONDAY. WITH THE TRACK OF THE LOW ON SUNDAY...WOULD EXPECT THE
PRECIPITATION TO STAY JUST SOUTHEAST OF THE CWA...BUT THE WINDS WILL
TURN TO A NORTHERLY DIRECTION AND BRING COLDER AIR INTO THE AREA
SATURDAY NIGHT THROUGH MONDAY. THIS WILL BRING INCREASING CHANCES OF
LAKE EFFECT SNOW FOR SATURDAY NIGHT THROUGH SUNDAY. STILL SOME
DIFFERENCES IN LOW LEVEL WINDS IN THE GFS/ECMWF...BUT A GENERAL
NORTH TO NORTHWEST WIND LAKE EFFECT SEEMS LIKELY (850MB TEMPS
FALLING TO -23C). ONE CONCERN IS FOR THE DECENT SUBSIDENCE ON THE
BACK SIDE OF THE LOW AIDED BY THE APPROACHING HIGH. MODEL SOUNDINGS
SHOW THAT SUBSIDENCE LIMITING INVERSION HEIGHTS TO 5-6KFT AND WOULD
PUT A CRIMP ON STRONGER LAKE EFFECT SNOW SHOWERS. LIKE THE IDEA OF
THE PREVIOUS SHIFT OF HIGH CHANCE AND LOW LIKELY POPS FOR THE
NORTHERLY AREAS ON SUNDAY AND THEN SHIFTED TOWARDS NORTHWEST SUNDAY
NIGHT. BACKING WINDS AND INCREASING SUBSIDENCE ASSOCIATED WITH THE
HIGH ON MONDAY WILL LEAD TO LOWER POPS AND A TREND TOWARDS WESTERLY
WIND AREAS.
WITH THAT COLD AIR...EXPECT HIGHS TO BE SIMILAR TO WHAT WE HAVE
SEEN RECENTLY AND HAVE TRENDED HIGHS DOWN INTO THE TEENS FOR SUNDAY
(TEMPS FALLING IN THE AFTERNOON) AND KEPT THAT SAME IDEA FOR MONDAY.
SHOULD BE A CHILLY NIGHT FOR AREAS AWAY FROM THE LAKE EFFECT ON
SUNDAY NIGHT AND HAVE TRENDED LOWS DOWN INTO THE SINGLE DIGITS BELOW
ZERO.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z WEDNESDAY AFTERNOON)
ISSUED AT 1225 PM EST TUE DEC 17 2013
AS A COLD FNT/AREA OF DEEPER MSTR SURGE ACROSS UPR MI THIS AFTN/
EVNG...EXPECT A PERIOD OF IFR CONDITIONS TO IMPACT IWD AND
ESPECIALLY CMX...WHERE SHARPER UPSLOPE WIND COMPONENT/GREAT EXPOSURE
TO FCST WNW WIND WL ENHANCE THE SHSN/BLSN AND POTENTIAL FOR LOWER
CIGS. SAW MAY SEE MVFR CONDITIONS WITH A DOWNSLOPE WIND COMPONENT
LIMITING THE POTENTIAL FOR LOWER CONDITIONS. THE APRCH OF A HI PRES
RDG AXIS/DRIER AIR LATER TNGT WL CAUSE IMPROVING WX...WITH
CONDITIONS IMPROVING TO VFR LATER TNGT W-E FOLLOWING THE PASSAGE OF
RDG AXIS WSHFT TO THE SW. A MORE PERSISTENT UPSLOPE WIND COMPONENT
WL SLOW THE IMPROVEMENT AT CMX.
&&
.MARINE...(FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 343 PM EST TUE DEC 17 2013
EXPECT NW WINDS TO 25-30 KTS THIS EVENING BEHIND A COLD FRONTAL
PASSAGE TO DIMINISH AND BACK TO THE SW WITH APPROACH OF A HI PRES
RIDGE LATER TONIGHT INTO WED. A VERY CHANGEABLE WEATHER PATTERN WILL
THEN DOMINATE THE UPPER GREAT LAKES THE REST OF THE WEEK...WITH HARD
TO TIME DISTURBANCES IMPACTING LAKE SUPERIOR. CONFIDENCE IS LOW IN
TIMING THESE DISTURBANCES AND ACCOMPANYING WIND SHIFTS...BUT GALES
APPEAR UNLIKELY THRU THE FORECAST PERIOD.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
NONE.
LAKE MICHIGAN...
NONE.
&&
$$
SHORT TERM...KC
LONG TERM...SRF
AVIATION...KC
MARINE...KC
AREA FORECAST DISCUSSION
NWS GAYLORD MI
108 PM EST TUE DEC 17 2013
.SYNOPSIS...
ISSUED AT 433 AM EST TUE DEC 17 2013
LIGHT ACCUMULATIONS ARE EXPECTED OVER NORTHWEST LOWER AND NORTHERN
CHIPPEWA COUNTY...WHERE LAKE EFFECT SNOW WILL CONTINUE THROUGH THE
DAY AND THEN INTENSIFY LATE THIS EVENING PROVIDING POSSIBLY LOCALLY
MODERATE SNOWFALL ACCUMULATIONS. CONTINUED BOUTS OF OCCASIONAL SNOW
ARE EXPECTED OVER THE NEXT COUPLE OF DAYS...AS MULTIPLE SYSTEMS PASS
THROUGH THE AREA. AFTER TODAY...WE WILL SEE SOMEWHAT MILDER
TEMPERATURES IN THE REGION.
&&
.UPDATE...
ISSUED AT 1251 PM EST TUE DEC 17 2013
THE SNOW BAND IN THE M-55 CORRIDOR WILL CONTINUE EAST, AND IT
SEEMS WILL DIMINISH OVER THE NEXT COUPLE OF HOURS. OTHERWISE,
WATCHING TO SEE IF THE LES WILL BEGIN TO FORM. THE LAST TROUGH HAS
TO GET ACROSS N LAKE MICHIGAN, BEFORE THAT HAPPENS. 850 MB
TEMPERATURES ARE GOOD, AS WELL AS THE 850-700 MB MOISTURE (RH>70%)
SO WILL BE ADJUSTING THE FORECAST AS THE LES BEGINS.
UPDATE ISSUED AT 1015 AM EST TUE DEC 17 2013
BAND OF SNOW IS MOVING SOUTH OF M-72 AND ALONG THE M-55 CORRIDOR.
SNOW HAS STRUGGLED TO GET MUCH NORTH OF THIS AREA. ONCE THE
INITIAL BAND IS THROUGH, THE SNOW SHOWERS BECOME SCATTERED, WITH
THE BACK EDGE ALONG A SECONDARY TROUGH (15Z RUC ANALYSIS). SO WILL
TWEAK THE POP GRIDS A BIT TO ACCOUNT FOR THE SNOW TRACK AND THE
BACK END OF THIS SYSTEM. THIS WOULD SEEMINGLY LEAVE MOST IF NOT
ALL OF THE M-32 CORRIDOR AND NORTH OUT OF THE SNOW THIS MORNING,
AND PROBABLY PART OF THE EARLY AFTERNOON. THERE IS VERY LITTLE
GOING ON IN LAKE SUPERIOR SO WILL KEEP THE CHANCE POPS FOR THE
TIME BEING.
UPDATE ISSUED AT 649 AM EST TUE DEC 17 2013
BACK EDGE OF SYSTEM SNOWS EXITING NE LOWER BEHIND DEPARTING
SHORTWAVE. SUBSIDENCE AND DRYING FROM ALOFT IN ITS WAKE WITH SOME
REAL LOW CLOUDS SWEPT IN OVER MOST OF THE AREA. NEXT SHORTWAVE
ALREADY ABOUT TO EXERT ITSELF ON THE GTV BAY REGION
SOUTHWARD....WITH LIGHT SNOWS MOVING IN OVER THE NEXT FEW HOURS.
THERE IS ALSO A NARROW CORRIDOR OF MODERATE SNOWS SET TO AFFECT
AREAS CLOSER TO THE FRANKFORT...MANISTEE AND CADILLAC AREAS.
INCREASED CHANCES FOR SEEING SNOW THERE...AND ALSO BUMPED UP SNOW
AMOUNTS TO UP TO 2 INCHES. NOT OUT OF THE QUESTION TO SEE LOCALLY
HIGHER AMOUNTS AS THE CORRIDOR OF MODERATE SNOWS MAY TRAIN FOR A
COUPLE OF HOURS. THIS IS WORTH KEEPING A CLOSE EYE ON FOR A
POSSIBLE SNEAKIER HIGHER SNOWFALL.
&&
.SHORT TERM...(TODAY THROUGH TONIGHT)
ISSUED AT 433 AM EST TUE DEC 17 2013
IT SIMPLY DOESN`T STOP...AND THAT`S A GOOD THING FOR THE SNOW FAN
THAT I AM! BUT...LAKE PROCESSES THAT ARE ON PERPETUAL OVERDRIVE SURE
MAKES FOR SOME CHALLENGING FORECAST SHIFTS. THIS ONE IS NO DIFFERENT
(WHY WOULD IT BE?)...WITH A FULL-FLEDGED SOUTHWEST FLOW EVENT
IMPACTING EASTERN UPPER AS IF THIS TYPING...NO DOUBT HELPED ALONG BY
PASSING SHORTWAVE TROUGH/ALBERTA CLIPPER TYPE SYSTEM. SYSTEM ITSELF
HAS A TOUCH OF SNOW WITH IT...BRINGING SOME LIGHT ACCUMULATIONS TO
MOST. PATTERN REMAINS IN RAPID-FIRE MODE...WITH NEXT SHORTWAVE AND
POCKET OF UPWARD QG SUPPORT ALREADY RACING EAST INTO WESTERN
WISCONSIN. PLETHORA OF FORECAST CHALLENGES GIVEN THIS ENERGETIC...
LAKE ENHANCED RICH PATTERN...WITH MAIN EMPHASIS CENTERED ONCE AGAIN
ON ADDITIONAL SNOW AMOUNTS AND ASSOCIATED HEADLINE CONCERNS.
OVERHEAD WAVE LOOKS TO EXIT QUICKLY EARLY THIS MORNING...WITH
SUBSIDENCE AND MID LEVEL DRYING KICKING IN BEHIND IT. WIDESPREAD
SNOWS WILL FOLLOW SUITE...ENDING FROM WEST TO EAST WITHIN THE NEXT
FEW HOURS. MAIN CONCERN REMAINS IMPRESSIVE...BUT INCREASING TRANSIENT
...SOUTHWEST FLOW BAND EXTENDING FROM LEELANAU COUNTY UP
INTO THE STRAITS. WINDS ALREADY VEERING CONSIDERABLY OVER THE
WESTERN HALF OF THE BIG POND...AND SIMPLE EXTRAPOLATION WOULD
SUGGEST THIS WIND SHIFT LINE PROPELLING THE BAND INLAND QUICKLY
SHORTLY AFTER ISSUANCE OF THIS FORECAST PACKAGE. NO DOUBT A BURST OF
VERY HEAVY SNOW WILL ACCOMPANY THIS BAND...LIKELY IN EXCESS OF ONE
INCH PER HOUR. HOWEVER...THIS LOOKS TO BE A SHORT-LIVED EVENT FROM
THIS POINT ON...AND WILL SIMPLY CANCEL ALL INHERITED ADVISORIES.
NEXT LOW AMPLITUDE WAVE APPROACHES QUICKLY THIS MORNING...WITH MAIN
CORE OF DYNAMICS SPREADING BY TO OUR SOUTH. BEST CHANCE FOR
ATTENDANT LIGHT SNOW EXPECTED ACROSS THE SOUTH THIRD OF THE AREA.
LAKE SUPPORT BY THIS TIME LOOK NEGLIGIBLE AS H8 TEMPERATURES "WARM"
TO AROUND -8C BY SUNRISE. THUS...NOT EXPECTING A WHOLE LOT OF
ADDITIONAL ACCUMULATION TODAY...LIKELY JUST AROUND AN INCH OR SO
FROM CADILLAC AND POINTS WEST. MORE SCATTERED AND LIGHTER SNOW
SHOWERS EXPECTED ELSEWHERE TODAY WITH MINIMAL ACCUMULATIONS. MIGHT
ACTUALLY FEEL KINDA BALMY AS HIGHS REACH INTO THE MIDDLE...AND
PERHAPS...UPPER 20S.
LAKE CONCERNS RAMP UP ONCE AGAIN TONIGHT AS WINDS SWING AROUND
WEST/NORTHWESTERLY AND NEXT SLUG OF COLDER AIR DROPS INTO THE
NORTHERN LAKES. HOWEVER...UNLIKE RECENT ARCTIC PLUNGES...THIS ONE IS
NOT QUITE AS COLD...WITH H8 TEMPERATURES ONLY FALLING INTO THE
NEGATIVE MID TEENS BY MORNING. BACKGROUND SYNOPTIC MOISTURE NOT TOO
SHABBY AT ALL...WITH GOOD MOISTURE THROUGH RESPECTABLE 750MB CBL
HEIGHT. WHILE STRONGEST OMEGA IS PEGGED JUST SHORT OF THE DGZ...AT
LEAST SOME LIFT IS NOTED IN THE BOTTOM END OF THIS ZONE. LACK OF
WELL-DEFINED LOW LEVEL CONVERGENCE AXES AND SOMEWHAT MORE MARGINAL
PARAMETERS LISTED ABOVE SHOULD KEEP THIS FROM BECOMING TOO BIG OF AN
EVENT. HAVE TENTATIVELY PAINTED IN 2 TO 4 INCHES IN THE TRADITIONAL
LAKE SNOW BELTS OF BOTH PENINSULAS BY MORNING. DEFINITELY NOT OUT OF
THE REALM OF POSSIBILITY FOR LOCALLY HIGHER AMOUNTS AND HEADLINES.
WILL PUNT THIS DECISION TO THE DAY CREW...LEAVING TIME TO MORE
THOROUGHLY ACCESS INCOMING AIRMASS VIA 12Z RAOBS. LOWS TONIGHT BACK
DOWN INTO THE TEENS.
.LONG TERM...(WEDNESDAY THROUGH MONDAY)
ISSUED AT 433 AM EST TUE DEC 17 2013
NRN MICHIGAN WILL BE UNDERWAY INTO A LESS COLD PATTERN WITH
TEMPERATURES RETURNING TO MORE NEAR NORMAL LEVELS...AS DEEPER UPPER
TROUGHING IS REPLACED BY A FASTER MORE ZONAL FLOW ALOFT. UPSTREAM
TROUGHING WILL HOWEVER SEND SOME ENERGY INTO THE GREAT LAKES
WEDNESDAY...BEFORE CUTTING OFF ACROSS THE WESTERN CONUS. GETS A TAD
MORE ACTIVE THURSDAY NIGHT AND OVER THE WEEKEND WITH CUTOFF LOW
DIGGING INTO THE FAR SRN ROCKIES...AND OVERALL UPPER AIR PATTERN
BECOMING MORE AMPLIFIED BY THE COMING WEEKEND. THERE IS AN EXPECTED
TAP OF DEEPER GULF MOISTURE WITH TIME...WITH BOTH JETS USHERING IN
SHORTWAVE ENERGY...NOT PHASING PER SE...BUT CERTAINLY THE CHANCE FOR
A SIGNIFICANT STORM SYSTEM IN THE EASTERN PART OF THE COUNTRY...WITH
AN ASSOCIATED CORRIDOR OF HEAVIER SNOW SOMEWHERE ACROSS OUR NECK OF
THE WOODS.
WEDNESDAY THROUGH THURSDAY...A RELATIVELY QUIET PERIOD OF WEATHER
WITH THE COLD UPPER TROUGH EXITING EAST AND FLOW GOING RATHER ZONAL.
A KINK/SHORTWAVE IN THE WNW FLOW ALOFT OVER ONTARIO WILL DAMPEN AS
IT CROSSES TO OUR NORTH...INDUCING A WEAK SFC LOW/CLIPPER. THIS
CLIPPER WILL BE LOSING STRENGTH AS IT LIFTS A WARM FRONT AND BAND OF
DEEPER MOISTURE THROUGH NRN MICHIGAN WEDNESDAY AND WEDNESDAY
EVENING. LIKELY SOME SCATTERED LIGHT LAKE EFFECT SNOW SHOWERS IN
WESTERLY FLOW REGIMES...AT LEAST IN THE MORNING WITH MINIMAL
ACCUMULATIONS UNDER AN INCH. LOW LEVEL FLOW AHEAD OF THE CLIPPER
WILL BRING WARMER LOW LEVEL TEMPERATURES TO EVENTUALLY SHUT OFF ANY
LES. SNOW CHANCES FROM THE SYSTEM ITSELF IS RATHER MINIMAL AS WELL
WITH AN INITIAL DRY LAYER H8-H7 LAYER GETTING SATURATED BRIEFLY
ALONG WITH THE UPPER LEVELS FOR A WINDOW OF OPPORTUNITY FOR A NARROW
CORRIDOR OF LIGHT SNOW TO PUSH ON THROUGH. WILL JUST HAVE SOME
SMALLISH CHANCES FOR NOW. A FAIRLY WEAK COLD FRONT DROPS IN OVER US
WEDNESDAY NIGHT INTO THURSDAY...BEFORE LAYING OUT ACROSS LOWER
MICHIGAN. WITH AN INCREASING LIGHT AND MORE VARIABLE FLOW DEVELOPING
AND SHALLOW SUB H8 MOISTURE IN THE MIX...A GOOD BET FOR SOME STRATUS
ISSUES. ACROSS THE EASTERN UP...MAYBE SOME LIGHT SNOW/FLURRIES IN
COLDEST AIR OFF LAKE SUPERIOR...BUT IT`S FAIRLY DRY. EXACT PLACEMENT
OF THE FRONT AND STRATUS HAS SOME UNCERTAINTY...BUT STILL NOT MUCH
EXPECTED FROM A SENSIBLE WEATHER STANDPOINT. WILL SEE SOME INCREASED
CLOUDS DEVELOPING LATER THURSDAY...AS INITIAL SRN STREAM ENERGY AND
NEXT NRN STREAM WEAK WAVE DROP IN TOWARD THE WESTERN GREAT LAKES.
THURSDAY NIGHT THROUGH SATURDAY...THAT FRONT WILL NOT BE
FORGOTTEN...AND IT`S PLACEMENT WILL BE IMPORTANT FOR THE THURSDAY
NIGHT AND EARLY FRIDAY TIME PERIOD. THE AFOREMENTIONED ENERGY FROM
BOTH STREAMS ARRIVE...AND TRY TO WORK WITH GULF MOISTURE TRYING TO
LIFT INTO THE LOWER AND MIDDLE MISSISSIPPI VALLEY. CLOUDS AND
PRECIPITATION ARE EXPECTED TO DEVELOP WITH DEEP MOISTURE SATURATING
THE COLUMN AS WEAK LOW PRESSURE DEVELOPS AND LIFTS NORTHEAST ALONG
THE LAID OUT FRONT. THERMAL PROFILES LOOK TO BE FOR AN ALL SNOW TYPE
EVENT FOR US...WITH AN OUTSIDE CHANCE THAT WE COULD SEE SOME RAIN
MIX IN ALONG THE M-55 CORRIDOR. THIS ALSO WHERE THE BEST CHANCES FOR
PRECIPITATION WILL RESIDE...BUT NRN STREAM WAVE WILL STILL PRESENT
ALL OF NRN MICHIGAN WITH A LIKELY SHOT OF LIGHT SNOW THROUGH FRIDAY
MORNING. AGAIN...WHERE THE FRONT WAS...AND WHETHER OR NOT IT SHIFTS
SOUTH...ARE KEY IN WHETHER OR NOT WE CAN GET SOME COLD ENOUGH AIR IN
HERE FOR SOME LIGHT LES SNOW SHOWERS...AND THERE IS QUITE A BIT OF
UNCERTAINTY THERE. EITHER WAY...EVEN WITH ANOTHER WEAK NRN STREAM
WAVE FRIDAY NIGHT INTO SATURDAY...ANY PRECIPITATION WE GET LOOKS TO
BE MINIMAL. ALL CONSIDERED...WILL NOT BE SURPRISED AT ALL...IF THERE
ISN`T SOME SORT OF LIGHT SNOW FLOATING AROUND.
SATURDAY NIGHT THROUGH MONDAY...POTENTIAL STORM? SRN STREAM CUTOFF
EXPECTED TO GET LIFTED INTO THE UPPER TROUGH...BUT NOT TOTALLY PHASE
TOGETHER. HOWEVER...A DEEP GULF OF MOISTURE TAP LIFTS NORTHWARD
AHEAD OF THE SRN STREAM WAVE...AND GET FORCED ALONG THE SFC FRONT
WHICH IS EXPECTED ALONG AND NORTH OF THE OHIO RIVER VALLEY....MAYBE
AS FAR NORTH AS SE LOWER MICHIGAN. A TIGHT BAROCLINIC ZONE DEVELOPS
AS LOW PRESSURE LIFTS TOWARD THE EASTERN GREAT LAKES. A CORRIDOR OF
HEAVY PRECIPITATION IS POSSIBLE ALONG THE FRONT...WITH THE NRN FRINGE
INTO COLD ENOUGH AIR FOR WHAT COULD WIND UP BEING AN AXIS OF HEAVIER
SNOWFALL FOR SOMEWHERE IN LOWER MICHIGAN. RIGHT NOW...MAYBE OUR FAR
SE COUNTIES SEEING SOME OF THIS ACTION??? REMAINS TO BE SEEN...AS
TIME DRAWS NEARER. NOT ENOUGH CONFIDENCE JUST YET FOR ANY MENTION
IN THE OUTLOOK SECTION OF THE HWOAPX.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z WEDNESDAY AFTERNOON)
ISSUED AT 1251 PM EST TUE DEC 17 2013
MVFR TO IFR CIGS ARE CONSTANT OVER THE REGION, AND WILL REMAIN AS
MUCH AS THE SECOND TROUGH MOVES THROUGH THE FORECAST AREA, AND
LAKE EFFECT SNOW BEGINS ALONG LAKE MICHIGAN. AT THIS POINT IT
LOOKS LIKE PLN AND TVC WILL BE MOST AFFECTED FROM THE WNW WIND
DIRECTION. MBL WILL GET SOME LAKE EFFECT, BUT PROBABLY NOT TO THE
EXTENT AS THE OTHER TWO. APN WILL BE ONLY GET SNOW AND VSBY
ISSUES, IF A SNOW BAND ELONGATES AND PASSES THROUGH THE SITE.
&&
.MARINE...
ISSUED AT 433 AM EST TUE DEC 17 2013
WEST/SOUTHWEST WINDS WILL SLOWLY VEER MORE WESTERLY...AND
EVENTUALLY NORTHWESTERLY TODAY INTO THIS EVENING. STRONGEST CORE
OF WINDS EXPECTED ACROSS NORTHERN LAKE MICHIGAN...WHERE SCA
CONDITIONS WILL CONTINUE RIGHT THROUGH TONIGHT. WINDS WILL QUICKLY
BACK SOUTHWESTERLY ONCE AGAIN WEDNESDAY WELL AHEAD OF NEXT
DEVELOPING LOW PRESSURE SYSTEM.
&&
.APX WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
LH...NONE.
LM...SMALL CRAFT ADVISORY UNTIL 5 AM EST WEDNESDAY FOR LMZ344>346.
LS...NONE.
&&
$$
UPDATE...JL
SYNOPSIS...TL
SHORT TERM...MB
LONG TERM...SD
AVIATION...JL
MARINE...MB
AREA FORECAST DISCUSSION
NWS GAYLORD MI
1038 AM EST TUE DEC 17 2013
.SYNOPSIS...
ISSUED AT 433 AM EST TUE DEC 17 2013
LIGHT ACCUMULATIONS ARE EXPECTED OVER NORTHWEST LOWER AND NORTHERN
CHIPPEWA COUNTY...WHERE LAKE EFFECT SNOW WILL CONTINUE THROUGH THE
DAY AND THEN INTENSIFY LATE THIS EVENING PROVIDING POSSIBLY LOCALLY
MODERATE SNOWFALL ACCUMULATIONS. CONTINUED BOUTS OF OCCASIONAL SNOW
ARE EXPECTED OVER THE NEXT COUPLE OF DAYS...AS MULTIPLE SYSTEMS PASS
THROUGH THE AREA. AFTER TODAY...WE WILL SEE SOMEWHAT MILDER
TEMPERATURES IN THE REGION.
&&
.UPDATE...
ISSUED AT 1015 AM EST TUE DEC 17 2013
BAND OF SNOW IS MOVING SOUTH OF M-72 AND ALONG THE M-55 CORRIDOR.
SNOW HAS STRUGGLED TO GET MUCH NORTH OF THIS AREA. ONCE THE
INITIAL BAND IS THROUGH, THE SNOW SHOWERS BECOME SCATTERED, WITH
THE BACK EDGE ALONG A SECONDARY TROUGH (15Z RUC ANALYSIS). SO WILL
TWEAK THE POP GRIDS A BIT TO ACCOUNT FOR THE SNOW TRACK AND THE
BACK END OF THIS SYSTEM. THIS WOULD SEEMINGLY LEAVE MOST IF NOT
ALL OF THE M-32 CORRIDOR AND NORTH OUT OF THE SNOW THIS MORNING,
AND PROBABLY PART OF THE EARLY AFTERNOON. THERE IS VERY LITTLE
GOING ON IN LAKE SUPERIOR SO WILL KEEP THE CHANCE POPS FOR THE
TIME BEING.
UPDATE ISSUED AT 649 AM EST TUE DEC 17 2013
BACK EDGE OF SYSTEM SNOWS EXITING NE LOWER BEHIND DEPARTING
SHORTWAVE. SUBSIDENCE AND DRYING FROM ALOFT IN ITS WAKE WITH SOME
REAL LOW CLOUDS SWEPT IN OVER MOST OF THE AREA. NEXT SHORTWAVE
ALREADY ABOUT TO EXERT ITSELF ON THE GTV BAY REGION
SOUTHWARD....WITH LIGHT SNOWS MOVING IN OVER THE NEXT FEW HOURS.
THERE IS ALSO A NARROW CORRIDOR OF MODERATE SNOWS SET TO AFFECT
AREAS CLOSER TO THE FRANKFORT...MANISTEE AND CADILLAC AREAS.
INCREASED CHANCES FOR SEEING SNOW THERE...AND ALSO BUMPED UP SNOW
AMOUNTS TO UP TO 2 INCHES. NOT OUT OF THE QUESTION TO SEE LOCALLY
HIGHER AMOUNTS AS THE CORRIDOR OF MODERATE SNOWS MAY TRAIN FOR A
COUPLE OF HOURS. THIS IS WORTH KEEPING A CLOSE EYE ON FOR A
POSSIBLE SNEAKIER HIGHER SNOWFALL.
&&
.SHORT TERM...(TODAY THROUGH TONIGHT)
ISSUED AT 433 AM EST TUE DEC 17 2013
IT SIMPLY DOESN`T STOP...AND THAT`S A GOOD THING FOR THE SNOW FAN
THAT I AM! BUT...LAKE PROCESSES THAT ARE ON PERPETUAL OVERDRIVE SURE
MAKES FOR SOME CHALLENGING FORECAST SHIFTS. THIS ONE IS NO DIFFERENT
(WHY WOULD IT BE?)...WITH A FULL-FLEDGED SOUTHWEST FLOW EVENT
IMPACTING EASTERN UPPER AS IF THIS TYPING...NO DOUBT HELPED ALONG BY
PASSING SHORTWAVE TROUGH/ALBERTA CLIPPER TYPE SYSTEM. SYSTEM ITSELF
HAS A TOUCH OF SNOW WITH IT...BRINGING SOME LIGHT ACCUMULATIONS TO
MOST. PATTERN REMAINS IN RAPID-FIRE MODE...WITH NEXT SHORTWAVE AND
POCKET OF UPWARD QG SUPPORT ALREADY RACING EAST INTO WESTERN
WISCONSIN. PLETHORA OF FORECAST CHALLENGES GIVEN THIS ENERGETIC...
LAKE ENHANCED RICH PATTERN...WITH MAIN EMPHASIS CENTERED ONCE AGAIN
ON ADDITIONAL SNOW AMOUNTS AND ASSOCIATED HEADLINE CONCERNS.
OVERHEAD WAVE LOOKS TO EXIT QUICKLY EARLY THIS MORNING...WITH
SUBSIDENCE AND MID LEVEL DRYING KICKING IN BEHIND IT. WIDESPREAD
SNOWS WILL FOLLOW SUITE...ENDING FROM WEST TO EAST WITHIN THE NEXT
FEW HOURS. MAIN CONCERN REMAINS IMPRESSIVE...BUT INCREASING TRANSIENT
...SOUTHWEST FLOW BAND EXTENDING FROM LEELANAU COUNTY UP
INTO THE STRAITS. WINDS ALREADY VEERING CONSIDERABLY OVER THE
WESTERN HALF OF THE BIG POND...AND SIMPLE EXTRAPOLATION WOULD
SUGGEST THIS WIND SHIFT LINE PROPELLING THE BAND INLAND QUICKLY
SHORTLY AFTER ISSUANCE OF THIS FORECAST PACKAGE. NO DOUBT A BURST OF
VERY HEAVY SNOW WILL ACCOMPANY THIS BAND...LIKELY IN EXCESS OF ONE
INCH PER HOUR. HOWEVER...THIS LOOKS TO BE A SHORT-LIVED EVENT FROM
THIS POINT ON...AND WILL SIMPLY CANCEL ALL INHERITED ADVISORIES.
NEXT LOW AMPLITUDE WAVE APPROACHES QUICKLY THIS MORNING...WITH MAIN
CORE OF DYNAMICS SPREADING BY TO OUR SOUTH. BEST CHANCE FOR
ATTENDANT LIGHT SNOW EXPECTED ACROSS THE SOUTH THIRD OF THE AREA.
LAKE SUPPORT BY THIS TIME LOOK NEGLIGIBLE AS H8 TEMPERATURES "WARM"
TO AROUND -8C BY SUNRISE. THUS...NOT EXPECTING A WHOLE LOT OF
ADDITIONAL ACCUMULATION TODAY...LIKELY JUST AROUND AN INCH OR SO
FROM CADILLAC AND POINTS WEST. MORE SCATTERED AND LIGHTER SNOW
SHOWERS EXPECTED ELSEWHERE TODAY WITH MINIMAL ACCUMULATIONS. MIGHT
ACTUALLY FEEL KINDA BALMY AS HIGHS REACH INTO THE MIDDLE...AND
PERHAPS...UPPER 20S.
LAKE CONCERNS RAMP UP ONCE AGAIN TONIGHT AS WINDS SWING AROUND
WEST/NORTHWESTERLY AND NEXT SLUG OF COLDER AIR DROPS INTO THE
NORTHERN LAKES. HOWEVER...UNLIKE RECENT ARCTIC PLUNGES...THIS ONE IS
NOT QUITE AS COLD...WITH H8 TEMPERATURES ONLY FALLING INTO THE
NEGATIVE MID TEENS BY MORNING. BACKGROUND SYNOPTIC MOISTURE NOT TOO
SHABBY AT ALL...WITH GOOD MOISTURE THROUGH RESPECTABLE 750MB CBL
HEIGHT. WHILE STRONGEST OMEGA IS PEGGED JUST SHORT OF THE DGZ...AT
LEAST SOME LIFT IS NOTED IN THE BOTTOM END OF THIS ZONE. LACK OF
WELL-DEFINED LOW LEVEL CONVERGENCE AXES AND SOMEWHAT MORE MARGINAL
PARAMETERS LISTED ABOVE SHOULD KEEP THIS FROM BECOMING TOO BIG OF AN
EVENT. HAVE TENTATIVELY PAINTED IN 2 TO 4 INCHES IN THE TRADITIONAL
LAKE SNOW BELTS OF BOTH PENINSULAS BY MORNING. DEFINITELY NOT OUT OF
THE REALM OF POSSIBILITY FOR LOCALLY HIGHER AMOUNTS AND HEADLINES.
WILL PUNT THIS DECISION TO THE DAY CREW...LEAVING TIME TO MORE
THOROUGHLY ACCESS INCOMING AIRMASS VIA 12Z RAOBS. LOWS TONIGHT BACK
DOWN INTO THE TEENS.
.LONG TERM...(WEDNESDAY THROUGH MONDAY)
ISSUED AT 433 AM EST TUE DEC 17 2013
NRN MICHIGAN WILL BE UNDERWAY INTO A LESS COLD PATTERN WITH
TEMPERATURES RETURNING TO MORE NEAR NORMAL LEVELS...AS DEEPER UPPER
TROUGHING IS REPLACED BY A FASTER MORE ZONAL FLOW ALOFT. UPSTREAM
TROUGHING WILL HOWEVER SEND SOME ENERGY INTO THE GREAT LAKES
WEDNESDAY...BEFORE CUTTING OFF ACROSS THE WESTERN CONUS. GETS A TAD
MORE ACTIVE THURSDAY NIGHT AND OVER THE WEEKEND WITH CUTOFF LOW
DIGGING INTO THE FAR SRN ROCKIES...AND OVERALL UPPER AIR PATTERN
BECOMING MORE AMPLIFIED BY THE COMING WEEKEND. THERE IS AN EXPECTED
TAP OF DEEPER GULF MOISTURE WITH TIME...WITH BOTH JETS USHERING IN
SHORTWAVE ENERGY...NOT PHASING PER SE...BUT CERTAINLY THE CHANCE FOR
A SIGNIFICANT STORM SYSTEM IN THE EASTERN PART OF THE COUNTRY...WITH
AN ASSOCIATED CORRIDOR OF HEAVIER SNOW SOMEWHERE ACROSS OUR NECK OF
THE WOODS.
WEDNESDAY THROUGH THURSDAY...A RELATIVELY QUIET PERIOD OF WEATHER
WITH THE COLD UPPER TROUGH EXITING EAST AND FLOW GOING RATHER ZONAL.
A KINK/SHORTWAVE IN THE WNW FLOW ALOFT OVER ONTARIO WILL DAMPEN AS
IT CROSSES TO OUR NORTH...INDUCING A WEAK SFC LOW/CLIPPER. THIS
CLIPPER WILL BE LOSING STRENGTH AS IT LIFTS A WARM FRONT AND BAND OF
DEEPER MOISTURE THROUGH NRN MICHIGAN WEDNESDAY AND WEDNESDAY
EVENING. LIKELY SOME SCATTERED LIGHT LAKE EFFECT SNOW SHOWERS IN
WESTERLY FLOW REGIMES...AT LEAST IN THE MORNING WITH MINIMAL
ACCUMULATIONS UNDER AN INCH. LOW LEVEL FLOW AHEAD OF THE CLIPPER
WILL BRING WARMER LOW LEVEL TEMPERATURES TO EVENTUALLY SHUT OFF ANY
LES. SNOW CHANCES FROM THE SYSTEM ITSELF IS RATHER MINIMAL AS WELL
WITH AN INITIAL DRY LAYER H8-H7 LAYER GETTING SATURATED BRIEFLY
ALONG WITH THE UPPER LEVELS FOR A WINDOW OF OPPORTUNITY FOR A NARROW
CORRIDOR OF LIGHT SNOW TO PUSH ON THROUGH. WILL JUST HAVE SOME
SMALLISH CHANCES FOR NOW. A FAIRLY WEAK COLD FRONT DROPS IN OVER US
WEDNESDAY NIGHT INTO THURSDAY...BEFORE LAYING OUT ACROSS LOWER
MICHIGAN. WITH AN INCREASING LIGHT AND MORE VARIABLE FLOW DEVELOPING
AND SHALLOW SUB H8 MOISTURE IN THE MIX...A GOOD BET FOR SOME STRATUS
ISSUES. ACROSS THE EASTERN UP...MAYBE SOME LIGHT SNOW/FLURRIES IN
COLDEST AIR OFF LAKE SUPERIOR...BUT IT`S FAIRLY DRY. EXACT PLACEMENT
OF THE FRONT AND STRATUS HAS SOME UNCERTAINTY...BUT STILL NOT MUCH
EXPECTED FROM A SENSIBLE WEATHER STANDPOINT. WILL SEE SOME INCREASED
CLOUDS DEVELOPING LATER THURSDAY...AS INITIAL SRN STREAM ENERGY AND
NEXT NRN STREAM WEAK WAVE DROP IN TOWARD THE WESTERN GREAT LAKES.
THURSDAY NIGHT THROUGH SATURDAY...THAT FRONT WILL NOT BE
FORGOTTEN...AND IT`S PLACEMENT WILL BE IMPORTANT FOR THE THURSDAY
NIGHT AND EARLY FRIDAY TIME PERIOD. THE AFOREMENTIONED ENERGY FROM
BOTH STREAMS ARRIVE...AND TRY TO WORK WITH GULF MOISTURE TRYING TO
LIFT INTO THE LOWER AND MIDDLE MISSISSIPPI VALLEY. CLOUDS AND
PRECIPITATION ARE EXPECTED TO DEVELOP WITH DEEP MOISTURE SATURATING
THE COLUMN AS WEAK LOW PRESSURE DEVELOPS AND LIFTS NORTHEAST ALONG
THE LAID OUT FRONT. THERMAL PROFILES LOOK TO BE FOR AN ALL SNOW TYPE
EVENT FOR US...WITH AN OUTSIDE CHANCE THAT WE COULD SEE SOME RAIN
MIX IN ALONG THE M-55 CORRIDOR. THIS ALSO WHERE THE BEST CHANCES FOR
PRECIPITATION WILL RESIDE...BUT NRN STREAM WAVE WILL STILL PRESENT
ALL OF NRN MICHIGAN WITH A LIKELY SHOT OF LIGHT SNOW THROUGH FRIDAY
MORNING. AGAIN...WHERE THE FRONT WAS...AND WHETHER OR NOT IT SHIFTS
SOUTH...ARE KEY IN WHETHER OR NOT WE CAN GET SOME COLD ENOUGH AIR IN
HERE FOR SOME LIGHT LES SNOW SHOWERS...AND THERE IS QUITE A BIT OF
UNCERTAINTY THERE. EITHER WAY...EVEN WITH ANOTHER WEAK NRN STREAM
WAVE FRIDAY NIGHT INTO SATURDAY...ANY PRECIPITATION WE GET LOOKS TO
BE MINIMAL. ALL CONSIDERED...WILL NOT BE SURPRISED AT ALL...IF THERE
ISN`T SOME SORT OF LIGHT SNOW FLOATING AROUND.
SATURDAY NIGHT THROUGH MONDAY...POTENTIAL STORM? SRN STREAM CUTOFF
EXPECTED TO GET LIFTED INTO THE UPPER TROUGH...BUT NOT TOTALLY PHASE
TOGETHER. HOWEVER...A DEEP GULF OF MOISTURE TAP LIFTS NORTHWARD
AHEAD OF THE SRN STREAM WAVE...AND GET FORCED ALONG THE SFC FRONT
WHICH IS EXPECTED ALONG AND NORTH OF THE OHIO RIVER VALLEY....MAYBE
AS FAR NORTH AS SE LOWER MICHIGAN. A TIGHT BAROCLINIC ZONE DEVELOPS
AS LOW PRESSURE LIFTS TOWARD THE EASTERN GREAT LAKES. A CORRIDOR OF
HEAVY PRECIPITATION IS POSSIBLE ALONG THE FRONT...WITH THE NRN FRINGE
INTO COLD ENOUGH AIR FOR WHAT COULD WIND UP BEING AN AXIS OF HEAVIER
SNOWFALL FOR SOMEWHERE IN LOWER MICHIGAN. RIGHT NOW...MAYBE OUR FAR
SE COUNTIES SEEING SOME OF THIS ACTION??? REMAINS TO BE SEEN...AS
TIME DRAWS NEARER. NOT ENOUGH CONFIDENCE JUST YET FOR ANY MENTION
IN THE OUTLOOK SECTION OF THE HWOAPX.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z WEDNESDAY MORNING)
ISSUED AT 629 AM EST TUE DEC 17 2013
IFR/LOW MVFR CIGS HAS SWEPT IN OVER MUCH OF THE AREA...WITH APN
ABOUT TO SEE CIGS COME DOWN. THIS IN SUBSIDENCE REGION BEHIND
DEPARTING DISTURBANCE ALOFT. MVFR TO BE THE PREVAILING CIG THROUGH
TONIGHT WITH MINIMAL MIXING IN LIGHTENING LOW LEVEL WINDS AS WEAK
LOW PRESSURE APPROACHES THROUGH THE DAY. ALREADY SEEING ADDITIONAL
LIGHT SNOWS WORKING INTO MBL...AND SOON TVC. COULD BE A 1-2 HR
PERIOD OF MORE MODERATE SNOWFALL NEAR MBL PER UPSTREAM RADAR AND
OBSERVATIONS...RESULTING IN 1/2SM SN AND IFR CONDITIONS. COLD
FRONT CROSSES LATE TODAY AND TONIGHT WITH INCREASING LES COVERAGE
AND INTENSITIES (MAINLY TONIGHT) FOR WNW FLOW AREAS THAT HIT
MAINLY BETWEEN PLN/TVC. REGARDLESS...EXPECT AT LEAST PERIODS OF
LAKE EFFECT SNOWS.
&&
.MARINE...
ISSUED AT 433 AM EST TUE DEC 17 2013
WEST/SOUTHWEST WINDS WILL SLOWLY VEER MORE WESTERLY...AND
EVENTUALLY NORTHWESTERLY TODAY INTO THIS EVENING. STRONGEST CORE
OF WINDS EXPECTED ACROSS NORTHERN LAKE MICHIGAN...WHERE SCA
CONDITIONS WILL CONTINUE RIGHT THROUGH TONIGHT. WINDS WILL QUICKLY
BACK SOUTHWESTERLY ONCE AGAIN WEDNESDAY WELL AHEAD OF NEXT
DEVELOPING LOW PRESSURE SYSTEM.
&&
.APX WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
LH...NONE.
LM...SMALL CRAFT ADVISORY UNTIL 5 AM EST WEDNESDAY FOR LMZ344>346.
LS...NONE.
&&
$$
UPDATE...JL
SYNOPSIS...TL
SHORT TERM...MB
LONG TERM...SD
AVIATION...SD
MARINE...MB
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
1226 AM EST TUE DEC 17 2013
.SHORT TERM...(THIS EVENING THROUGH TUESDAY)
ISSUED AT 347 PM EST MON DEC 16 2013
12Z RAOBS/LATEST WV IMAGERY AND RUC ANALYSIS SHOWS PERSISTENT NW
FLOW ALF OVER THE GREAT LKS BTWN DEEP TROF OVER ERN NAMERICA AND RDG
ALONG THE W COAST. VERY COLD CNDN AIR IS IN PLACE OVER THE UPR LKS
WITH H5/H85 TEMPS JUST UNDER -30C/ARND -18 OR 19C. DISTURBANCE
RESPONSIBLE FOR SN ON SUN HAS NOW PUSHED E INTO QUEBEC...BUT ANOTHER
WELL DEFINED CLIPPER SHRTWV JUST E OF LK WINNIPEG EARLY THIS AFTN IS
FOLLOWING QUICKLY BEHIND. SHRTWV RDG/DRY MID LVL AIR SHOWN ON THE
12Z APX/GRB RAOBS BROUGHT DRY WX TO UPR MI EARLY THIS AFTN. ALTHOUGH
ABSOLUTE MSTR IS LIMITED FOR THE TRAILING DISTURBANCE WITH 12Z PWATS
NO HIER THAN 0.25-0.35 INCH IN MN...A BAND OF SN UNDER THE DEEP LYR
QVECTOR CNVGC/DPVA/ISENTROPIC ASCENT AHEAD OF THIS FEATURE IS MOVING
INTO WRN LK SUP. THE BAND IS RATHER NARROW...BUT VSBYS UNDER THE
HEAVIER SN HAVE FALLEN AS LO AS 1/4-3/4 MILES. THIS SN BAND SHIFTED
INTO THE WRN COUNTIES BY MID AFTN...AND THE VSBY AT IWD DROPPED TO
1/4SM FOR AN HR. SOME SHSN AND PERHAPS A VORTEX ARE PRESENT OVER
NCNTRL LK MI...AND THESE ARE DRIFTING TO THE NNE. ALTHOUGH SOME
LIGHT SN LINGERS BACK INTO NW MN BEHIND THIS BAND...VSBYS THERE ARE
AOA 3 MILES UNDER THE UPR LVL DRYING SHOWN ON WV IMAGERY/QVECTOR
DVGC IN THE WAKE OF THE SHRTWV TROF. IN FACT...THERE HAS BEEN SOME
CLRG OVER CENTRAL MN. FARTHER TO THE NW...THERE IS ANOTHER CLIPPER
DISTURBANCE DIGGING SEWD IN SASKATCHEWAN.
MAIN FCST CONCERNS IN THE SHORT TERM INVOLVE POPS/SN AMNTS AND GOING
HEADLINE OVER THE ERN CWA ASSOCIATED WITH APRCHG CLIPPER SHRTWV.
FOCUS FOR TUE SHIFTS TO POTENTIAL IMPACT OF SECOND TRAILING
DISTURBANCE IN WRN CANADA AS WELL AS THE CHC FOR MORE LK EFFECT SN.
LATE THIS AFTN/THRU THIS EVNG...TENDED TO BUMP POPS UP TO
CATEGORICAL FOR A FEW HRS AT MOST PLACES W-E THIS AFTN INTO EARLY
EVNG WITH PASSAGE OF RATHER NARROW BAND OF SN UNDER AXIS OF H85-5
QVECTOR CNVGC AHEAD OF APRCHG SHRTWV. WITH 2G/KG SPECIFIC HUMIDITY
PRESENT NEAR H725 AND A 2-3 HR PERIOD OF HEAVIER SN...EXPECT MOST
PLACES WL SEE ARND AN INCH TO PERHAPS 2 INCHES OF SN UNDER THIS
HEAVIER BURST. THE ONE EXCEPTION WL BE IN THE SSW FLOW DOWNWIND OF
LK MI...WHERE SOME LK ENHANCEMENT WITH H85 TEMPS NEAR -16C/DEEPER
MSTR/DYNAMIC FORCING JUSTIFIES GOING WINTER WX ADVY UNTIL PASSAGE OF
THE BAND/WSHFT TO THE WSW AFT MIDNGT OVER THE E WL DIMINISH THESE
SHSN. FVRBL OMEGA PROFILE WITHIN THE DGZ WL AID IN SN ACCUMS. TO THE
W...JUST SOME LINGERING SCT -SHSN WL FOLLOW THE BAND UNDER MID LVL
DRYING/QVECTOR DVGC. WHERE THERE IS A BETTER CHC FOR AT LEAST
PARTIAL CLRG OVER THE SCNTRL...TENDED TO LOWER FCST MIN TEMPS A BIT
WELL INTO THE SINGLE NUMBERS ABV ZERO.
LATER TNGT/TUE...MOST OF THE EARLY MRNG SHOULD BE MOCLDY WITH JUST
SOME SCT -SHSN/FLURRIES UNDER QVECTOR DVGC IN THE WAKE OF THE
DEPARTING CLIPPER. THE SHRTWV NOW OVER SASKATCHEWAN IS FCST TO DIG
SEWD AND INTO THE UPR LKS BY 12Z TUE. ALTHOUGH MORE IMPRESSIVE
MSTR/DYNAMIC FORCING WL ACCOMPANY ANOTHER SHRTWV PASSING TO THE S IN
WI...ARRIVAL OF COLD FNT/DEEPER MSTR ASSOCIATED WITH THE
SASKATCHEWAN DISTURBANCE WL BRING A RETURN OF HIER POPS TO MAINLY NW
UPR MI ON TUE MRNG. THERE IS SOME DISAGREEMENT AMONG THE MODELS ON
HOW MUCH DEEPER MSTR WL ACCOMPANY THIS FROPA. IN GENERAL...THE 12Z
NAM/GFS SHOW MORE FVRBL ALIGNMENT BTWN THE DEEPER MSTR AND FROPA
TIMING. ALTHOUGH THERE IS SOME POTENTIAL FOR A BRIEF PERIOD OF LK
ENHANCED SN WITH H85 TEMPS RISING TO -10C IN THE NARROW THERMAL RDG
AHEAD OF THIS FNT...THE NAM/GFS SHOW DEEPER MSTR LINGERING FOR ONLY
A 3-6HR PERIOD. AS THE FNT SHIFTS TO THE E...THESE SHSN WL FOLLOW
THE BNDRY...WITH THE HIER POPS CLOSER TO LK SUP. BUT WL CARRY LOWER
CHC POPS EVEN OVER THE SCENTRAL...WHICH WL BE CLOSER TO THE DYNAMIC
FORCING ASSOCIATED WITH SHRTWV PASSING THRU WI. AFTER THE HEAVIER
SHSN END OVER THE NW...EXPECT LIGHTER MULTIPLE BAND LES TO IMPACT
THE WNW WIND SN BELTS THERE AS COLDER AIR WITH H85 TEMPS FALLING TO
ARND -18C BY 00Z WED FOLLOW THE BNDRY. NOT OUT OF THE QUESTION THERE
COULD BE ADVY SN FALL OVER THE NW THRU THE DAY...BUT CONCERNS
ABOUT TIMING OF DEEPER MSTR LOWER CONFIDENCE ENUF TO HOLD OFF ON A
HEADLINE FOR NOW.
.LONG TERM...(TUESDAY NIGHT THROUGH MONDAY)
ISSUED AT 440 PM EST MON DEC 16 2013
EXPECT CONTINUED NW FLOW OVER THE KEWEENAW PENINSULA TUESDAY EVENING
WITH ANOTHER 1 TO ALMOST 2IN. A QUICK 1-4IN OF SNOW WILL BE POSSIBLE
E OF MUNISING AND N OF NEWBERRY TUESDAY NIGHT. MAY NEED TO HOIST A
LES ADVISORY FOR E ALGER AND N PORTIONS OF LUCE COUNTY...WITH THE
CONVERGENCE BEHIND THE EXITING LOW.
WITH THE 500MB TROUGH SET UP FROM E ONTARIO THROUGH THE LOWER GREAT
LAKES...AND A SIZABLE RIDGE DOMINATING THE W HALF OF THE
NATION...CHANCES ARE GOOD FOR RIDGING TO MOVE IN FOR MID WEEK. THE
RIDGE WILL SLIDE IN AT THE SFC AND ALOFT WEDNESDAY MORNING...AHEAD
OF A BROAD AREA OF LOW PRESSURE SET UP FROM SW AND SCENTRAL CANADA
THROUGH THE NORTHERN PLAINS. THE WARM WEATHER WILL CONTINUE FOR
WEDNESDAY AHEAD OF THIS LOW. ENJOY IT WHILE IT LASTS. WHILE READINGS
WILL BE ABOVE WHAT WE HAVE BEEN USE TO /HAVE NOT HAD TEMPS ABOVE 15F
AT NWS MQT SINCE THE FIRST 5 DAYS OF DECEMBER/...THEY WILL REMAIN
AROUND NORMAL FOR THIS TIME OF YEAR. HIGHS ARE TYPICALLY IN THE MID
TO UPPER 20S IN MID DECEMBER.
EXPECT THE RIDGE ALOFT TO QUICKLY TURNING TO MORE ZONAL FLOW
WEDNESDAY NIGHT WITH BOOKEND TROUGHS OVER THE FAR W AND E SECTIONS
OF THE UNITED STATES. BY 00Z THURSDAY THE SFC LOW WILL HAVE MOVED TO
THE SE...STRETCHING FROM E CO THROUGH LAKE SUPERIOR.
THE N EXTENT OF THE SFC LOW WILL SLOWLY SINK ACROSS LAKE MI AND
LOWER MI THROUGH THE DAY THURSDAY...WITH SW FLOW AT 500MB ON
THURSDAY IN RESPONSE TO THE LOW DIVING ALONG THE W COAST INTO
CA...AND THE NORTHERN LOW PUSHING ACROSS CENTRAL CANADA. A QUICK
TENTH OF AN INCH OR SO OF LIQUID FROM THURSDAY AFTERNOON THROUGH
THURSDAY EVENING. WITH SNOW RATIOS OF 20-25:1...WILL LIKELY HAVE
1-2IN OF SNOW CWA WIDE BY MIDNIGHT.
THE SFC LOW WILL THEN CONSOLIDATE ACROSS LOWER MI AND LAKE HURON AT
12Z FRIDAY...WITH UPPER MI AND THE UPPER GREAT LAKES RETURNING TO
OUR TROUGH PATTERN FROM THURSDAY THROUGH NEXT MONDAY. ANOTHER 1-2IN
OF SNOW POSSIBLE BEFORE DRYING UP BY LATE FRIDAY MORNING.
A BRIEF RIDGE WILL ATTEMPT TO BUILD IN ALOFT SATURDAY OVER THE SE
CWA...AS THE NEXT SIGNIFICANT TROUGH PUSHES IN FROM CENTRAL CANADA
AND THE PLAINS STATES. A SERIES OF EMBEDDED WAVES WILL CONTINUE TO
NEAR FROM THE NW THROUGH AT LEAST MONDAY.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z TUESDAY NIGHT)
ISSUED AT 1226 AM EST TUE DEC 17 2013
A SERIES OF SHORTWAVE TROUGHS COMBINED WITH UPSLOPE FLOW AT CMX AND
IWD WILL BRING PERIODS OF LOWER CONDITIONS THROUGH THE TAF PERIOD AT
ALL SITES. THE WORST CONDITIONS ARE EXPECTED AT CMX AND IWD WHERE
UPSLOPE FLOW WILL FAVOR LOWER CIGS AND VIS. SKIES MAY CLEAR OUT
TONIGHT AT IWD AS SCATTERED CLEARING WAS NOTED UPSTREAM OVER
NCENTRAL MN...BUT NOT COMPLETELY CERTAIN ON EXTENT OF CLEARING
THERE. LOW LEVEL FLOW WILL NOT BE AS FAVORABLE FOR LOWER CONDITIONS
AT SAW...SO BEST CONDITIONS ARE EXPECTED THERE.
&&
.MARINE...(FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 355 PM EST MON DEC 16 2013
S WINDS UP TO 25 TO 30 KTS THIS AFTERNOON AHEAD OF AN APPROACHING
LOW PRESSURE TROUGH WILL SHIFT TO THE SW AND DIMINISH OVERNIGHT TO
20 TO 25 KTS AS THE TROUGH SHIFTS TO THE EAST. A STRONGER WEST TO
NORTHWEST WIND UP TO 30 KTS WILL DEVELOP ON TUE FOLLOWING THE
PASSAGE OF A COLD FRONT. NOT OUT OF THE QUESTION THERE COULD BE A
FEW GUSTS TO NEAR GALE FORCE OVER WESTERN LAKE SUPERIOR. NO GALES
ARE FORESEEN QUITE YET FROM TUESDAY NIGHT THROUGH
SATURDAY...ALTHOUGH A COUPLE OF PERIODS GET CLOSER TO GUSTS OF
25-30KTS. HIGH PRESSURE WILL MOVE INTO THE CENTRAL PLAINS TUESDAY
EVENING AND WILL PUSH A BRIEF RIDGE ACROSS LAKE SUPERIOR WEDNESDAY.
A TROUGH EXTENDING FROM A BROAD LOW OVER THE ROCKIES AND NORTHERN
PLAINS WILL MOVE INTO THE UPPER GREAT LAKES WEDNESDAY NIGHT AND
THURSDAY. EXPECT THE LOW TO SINK ACROSS LOWER MICHIGAN BY FRIDAY
MORNING. IN THE WAKE OF THE LOW...HIGH PRESSURE OVER THE CENTRAL
PLAINS FRIDAY MORNING SHOULD SLOWLY BUILD INTO THE UPPER GREAT LAKES
ON FRIDAY...AND REMAIN IN PLACE THROUGH FRIDAY NIGHT. WEAK LOW
PRESSURE WILL THEN PUSH ACROSS THE AREA FOR THE START OF THE WEEKEND.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
WINTER WEATHER ADVISORY UNTIL 1 AM EST EARLY THIS MORNING FOR
MIZ007-014.
LAKE SUPERIOR...
NONE.
LAKE MICHIGAN...
NONE.
&&
$$
SHORT TERM...KC
LONG TERM...KF
AVIATION...TITUS
MARINE...KC/KF
AREA FORECAST DISCUSSION
NWS NORTH PLATTE NE
1144 AM CST TUE DEC 17 2013
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 355 AM CST TUE DEC 17 2013
THE THERMAL RIDGE WEAKENED A BIT WITH THE PASSAGE OF A WEAK COLD
FRONT TONIGHT. AS A RESULT...HIGH PRESSURE IS BUILDING THROUGH THE
NRN AND CNTL HIGH PLAINS ALLOWING FOR RADIATIONAL COOLING IN MOST
VALLEYS. THE RUC SHOWS LOW PRESSURE REFORMING ACROSS THE HIGH
PLAINS TODAY AND THIS SHOULD LIFT A WARM FRONT PART WAY THROUGH
THE FCST AREA. THE WARM FRONT WOULD LIKELY REACH HIGHWAY 183 BY
LATE AFTN.
FCST HIGHS FOLLOW THE WARMEST MODEL...THE HRRR FOR HIGHS NEAR 60
ACROSS THE SOUTHWEST WHERE THE THERMAL RIDGE WILL BE IN PLACE ALL
DAY. JUST SCATTERED HIGH CLOUDS ARE EXPECTED AS A SOLID BANK OF
CIRRUS IS OVER BRITISH COLUMBIA THIS AM.
THE RAP MODEL SHOWS WEST WINDS AT H850MB AT 15 TO 30KT AND THE MODEL
CONSENSUS 500M AGL WINDS ARE WEST AND SOUTHWEST AT 10 TO 20KT WHICH
WOULD PRODUCE 10 TO 20 MPH WINDS AT THE SFC.
LOWS TONIGHT VARY WIDELY WITH TEENS IN VALLEYS TO NEAR 30 ACROSS THE
SANDHILLS. A SHALLOW INVERSION SHOULD FORM GIVEN THE LIMITED HIGH
CLOUD COVER EXPECTED AND WESTERLY H850MB WINDS OF 20 TO 40KT. H850MB
TEMPS RISE IN THE TEENS ACROSS WRN NEB.
.LONG TERM...(WEDNESDAY THROUGH MONDAY)
ISSUED AT 355 AM CST TUE DEC 17 2013
PRIMARY CONCERNS FOR THIS FORECAST PERIOD ARE TEMPERATURES FOR
WEDNESDAY AND THURSDAY...AS WELL AS PRECIPITATION CHANCES AND
TYPES FOR THURSDAY AND THURSDAY NIGHT.
THE SHORTWAVE TROUGH CURRENTLY OVER THE GULF OF ALASKA WILL SPLIT
WEDNESDAY AND WEDNESDAY NIGHT WHICH WILL IMPACT THE LOCAL AREA IN
DIFFERENT WAYS. ONE PART OF THIS ENERGY WILL DIG SOUTH ALONG THE
WEST COAST WHICH WILL HELP THE THERMAL RIDGE BUILD OVER THE PLAINS.
THE SECOND PIECE OF ENERGY WILL STAY IN THE NORTHERN STREAM WHICH
WILL MOVE ACROSS THE PLAINS AS A WEAK SHORTWAVE TROUGH THURSDAY AND
THURSDAY NIGHT...WHICH WILL PUSH AN ARCTIC COLD FRONT ACROSS THE
FORECAST AREA.
STARTING ON WEDNESDAY...IS STILL A QUESTION TO HOW WARM IT WILL GET.
AS MENTIONED ABOVE THE THERMAL RIDGE BUILDS IN WITH ANOMALOUSLY WARM
AIR SEEN ALOFT. AT 18Z WEDNESDAY MODELS INDICATE 850MB TEMPERATURES
WILL HAVE RISEN BETWEEN 11C AND 15C ACROSS WESTERN AND NORTH CENTRAL
NEBRASKA. MODELS ARE ONLY MIXING THE BOUNDARY LAYER TO AROUND 875MB
SO DON/T REALIZE THE POTENTIAL WARMING. WINDS WILL BE FAIRLY LIGHT
WHICH WON/T HELP THE MIXING DEPTH...BUT DON/T THINK THE MODELS ARE
HANDLING THIS MIXING WELL AND IN MOST LOCATIONS WENT ABOVE MOST
GUIDANCE FOR HIGHS. MUCH OF THE NORTHERN TIER OF COUNTIES CONTINUES
TO HAVE SNOW ON THE GROUND WHICH AS OF MONDAY STILL HAD A STRONG
IMPACT ON TEMPERATURES AS HIGHS WERE ONLY IN THE LOW 40S...WITH
UPPER 50S AND LOW 60S OVER THE REST OF THE FORECAST AREA. SHOULD
HAVE CONTINUED MELTING TODAY...SO THE SNOW SHOULDN/T HAVE AS MUCH
IMPACT ON HIGHS...BUT WITH WET GROUND MAY NOT BE ABLE TO MIX TOO
MUCH SO CONTINUED THE TREND OF COOLER TEMPERATURES ACROSS THE NORTH.
THIS MAY NEED TO BE MODIFIED DEPENDING ON WHAT HIGHS DO TODAY.
COLD FRONT WILL PUSH SOUTH THROUGH THE FORECAST AREA WEDNESDAY
NIGHT...WITH THE COLDEST AIR LAGGING BEHIND THE FRONT. THE LOW
LEVELS START TO SATURATE BY 12Z THURSDAY BUT ABUNDANT DRY AIR IN THE
MID LEVELS WILL KEEP FROM THE NEED FOR PRECIPITATION CHANCES
WEDNESDAY NIGHT.
ON THURSDAY...THERE ARE STILL DISCREPANCIES AS TO HOW FAST THE COLD
AIR WILL MOVE IN. FOR EXAMPLE GFS ENSEMBLE MEMBERS VARY FROM 19F TO
42F FOR HIGHS AT KLBF. BECAUSE OF THESE DIFFERENCES STAYED FAIRLY
SIMILAR TO ONGOING FORECAST FOR HIGHS. WITH COLD AIR ADVECTION
THROUGH THE DAY...MAY SEE HIGHS EARLY WITH FALLING OR NEARLY STEADY
TEMPERATURES. IN TERMS OF PRECIPITATION FOR THURSDAY...THERE IS
AGREEMENT BETWEEN MODEL SOLUTIONS OF THE COLUMN BECOMING SATURATED
THURSDAY MORNING OVER THE NORTHERN PANHANDLE...AND WITH THE COLD AIR
ALREADY IN PLACE SHOULD START TO SEE SNOW IN THE MORNING HOURS. AS
THE ENTIRE COLUMN COOLS...WITH SOME LAYERS REACHING THE DENDRITIC
GROWTH ZONE...MIGHT GET SOME HIGHER SNOW TO LIQUID RATIO SNOWS UP
OVER NORTHWEST NEBRASKA. ACTUALLY...BY LATE THURSDAY NIGHT MOST OF
THE SOUNDING IS ISOTHERMAL IN THE DENDRITIC GROWTH ZONE.
HOWEVER...AT THIS POINT THE UPPER LEVEL SYSTEM IS WELL PAST AND THE
AREA IS IN AN AREA OF SUBSIDENCE AND LIFT IS MINIMAL SO THERE IS
ENOUGH DISCONNECT BETWEEN THE FAVORABLE CONDITIONS TO LIMIT FROM
HEAVY SNOWS. COULD SEE A COUPLE INCHES...POSSIBLY UP TO 4 ON THE
PINE RIDGE. WILL PROBABLY SEE SOME LIGHT SNOW ACROSS THE REST OF
NORTHERN NEBRASKA...BUT ONSET WILL BE LATER IN THE DAY THURSDAY AND
WITH THE UPWARD FORCING MOSTLY GONE BY MIDNIGHT EXPECT JUST LIGHT
AMOUNTS. DIFFERENT CONCERN IS FREEZING DRIZZLE FOR CENTRAL CHERRY
COUNTY AND EASTWARD ON THURSDAY. THE LOWEST 2500FT BECOME SATURATED
BY 18Z THURSDAY ACCORDING TO SOUNDINGS AT KVTN...WHILE A DEEP DRY
MID LAYER MAY PROHIBIT SEEDER FEEDER MECHANISM FROM OCCURRING FOR A
FEW HOURS. THERE IS DECENT OMEGA IN THESE LOW LEVELS SO DID ADD
CHANCES FOR FREEZING DRIZZLE INTO THE FORECAST FOR THURSDAY.
WILL ALSO BE QUITE WINDY ON THURSDAY AND THURSDAY NIGHT BEHIND THE
COLD FRONT WHICH WILL DROP WIND CHILLS TO AROUND -10F BY FRIDAY
MORNING.
LOOKING INTO THE WEEKEND...THE UPPER LOW OVER THE SOUTHWEST WILL
MIGRATE ACROSS THE SOUTHERN PLAINS WHILE THE LOCAL AREA WILL SEE
ANOTHER SHORTWAVE TROUGH MOVE ACROSS THE AREA THROUGH THE NORTHERN
STREAM. THERE IS SOME DIFFERENCES ON TIMING OF THIS NEXT
SYSTEM...BUT SHOULD BE MOVING THROUGH SOMETIME SATURDAY NIGHT/SUNDAY.
DOESN/T LOOK LIKE MUCH FOR PRECIPITATION WITH THIS NEXT SYSTEM BUT
THERE IS POTENTIAL FOR ANOTHER PUSH OF ARCTIC AIR INTO THE AREA
BEHIND IT.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z WEDNESDAY AFTERNOON)
ISSUED AT 1141 AM CST TUE DEC 17 2013
VFR CONDITIONS THE NEXT 24 HOURS. NORTHWEST UPPER LEVEL FLOW WILL
FLATTEN SOME AS RIDGE MIGRATES EAST. PACIFIC MOISTURE WILL STREAM
ACROSS THE ROCKIES WITH FEW/SCT HIGH CLOUDS AT TIMES ACROSS THE
AREA. WINDS WILL BE VARIABLE AND LESS THAN 10 KTS...ALTHOUGH
PREVAILING WIND DIRECTION WILL BE WESTERLY TO SOUTHWESTERLY.
&&
.LBF WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...CDC
LONG TERM...BROOKS
AVIATION...MASEK
AREA FORECAST DISCUSSION...UPDATED
NWS NORTH PLATTE NE
520 AM CST TUE DEC 17 2013
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 355 AM CST TUE DEC 17 2013
THE THERMAL RIDGE WEAKENED A BIT WITH THE PASSAGE OF A WEAK COLD
FRONT TONIGHT. AS A RESULT...HIGH PRESSURE IS BUILDING THROUGH THE
NRN AND CNTL HIGH PLAINS ALLOWING FOR RADIATIONAL COOLING IN MOST
VALLEYS. THE RUC SHOWS LOW PRESSURE REFORMING ACROSS THE HIGH
PLAINS TODAY AND THIS SHOULD LIFT A WARM FRONT PART WAY THROUGH
THE FCST AREA. THE WARM FRONT WOULD LIKELY REACH HIGHWAY 183 BY
LATE AFTN.
FCST HIGHS FOLLOW THE WARMEST MODEL...THE HRRR FOR HIGHS NEAR 60
ACROSS THE SOUTHWEST WHERE THE THERMAL RIDGE WILL BE IN PLACE ALL
DAY. JUST SCATTERED HIGH CLOUDS ARE EXPECTED AS A SOLID BANK OF
CIRRUS IS OVER BRITISH COLUMBIA THIS AM.
THE RAP MODEL SHOWS WEST WINDS AT H850MB AT 15 TO 30KT AND THE MODEL
CONSENSUS 500M AGL WINDS ARE WEST AND SOUTHWEST AT 10 TO 20KT WHICH
WOULD PRODUCE 10 TO 20 MPH WINDS AT THE SFC.
LOWS TONIGHT VARY WIDELY WITH TEENS IN VALLEYS TO NEAR 30 ACROSS THE
SANDHILLS. A SHALLOW INVERSION SHOULD FORM GIVEN THE LIMITED HIGH
CLOUD COVER EXPECTED AND WESTERLY H850MB WINDS OF 20 TO 40KT. H850MB
TEMPS RISE IN THE TEENS ACROSS WRN NEB.
.LONG TERM...(WEDNESDAY THROUGH MONDAY)
ISSUED AT 355 AM CST TUE DEC 17 2013
PRIMARY CONCERNS FOR THIS FORECAST PERIOD ARE TEMPERATURES FOR
WEDNESDAY AND THURSDAY...AS WELL AS PRECIPITATION CHANCES AND
TYPES FOR THURSDAY AND THURSDAY NIGHT.
THE SHORTWAVE TROUGH CURRENTLY OVER THE GULF OF ALASKA WILL SPLIT
WEDNESDAY AND WEDNESDAY NIGHT WHICH WILL IMPACT THE LOCAL AREA IN
DIFFERENT WAYS. ONE PART OF THIS ENERGY WILL DIG SOUTH ALONG THE
WEST COAST WHICH WILL HELP THE THERMAL RIDGE BUILD OVER THE PLAINS.
THE SECOND PIECE OF ENERGY WILL STAY IN THE NORTHERN STREAM WHICH
WILL MOVE ACROSS THE PLAINS AS A WEAK SHORTWAVE TROUGH THURSDAY AND
THURSDAY NIGHT...WHICH WILL PUSH AN ARCTIC COLD FRONT ACROSS THE
FORECAST AREA.
STARTING ON WEDNESDAY...IS STILL A QUESTION TO HOW WARM IT WILL GET.
AS MENTIONED ABOVE THE THERMAL RIDGE BUILDS IN WITH ANOMALOUSLY WARM
AIR SEEN ALOFT. AT 18Z WEDNESDAY MODELS INDICATE 850MB TEMPERATURES
WILL HAVE RISEN BETWEEN 11C AND 15C ACROSS WESTERN AND NORTH CENTRAL
NEBRASKA. MODELS ARE ONLY MIXING THE BOUNDARY LAYER TO AROUND 875MB
SO DON/T REALIZE THE POTENTIAL WARMING. WINDS WILL BE FAIRLY LIGHT
WHICH WON/T HELP THE MIXING DEPTH...BUT DON/T THINK THE MODELS ARE
HANDLING THIS MIXING WELL AND IN MOST LOCATIONS WENT ABOVE MOST
GUIDANCE FOR HIGHS. MUCH OF THE NORTHERN TIER OF COUNTIES CONTINUES
TO HAVE SNOW ON THE GROUND WHICH AS OF MONDAY STILL HAD A STRONG
IMPACT ON TEMPERATURES AS HIGHS WERE ONLY IN THE LOW 40S...WITH
UPPER 50S AND LOW 60S OVER THE REST OF THE FORECAST AREA. SHOULD
HAVE CONTINUED MELTING TODAY...SO THE SNOW SHOULDN/T HAVE AS MUCH
IMPACT ON HIGHS...BUT WITH WET GROUND MAY NOT BE ABLE TO MIX TOO
MUCH SO CONTINUED THE TREND OF COOLER TEMPERATURES ACROSS THE NORTH.
THIS MAY NEED TO BE MODIFIED DEPENDING ON WHAT HIGHS DO TODAY.
COLD FRONT WILL PUSH SOUTH THROUGH THE FORECAST AREA WEDNESDAY
NIGHT...WITH THE COLDEST AIR LAGGING BEHIND THE FRONT. THE LOW
LEVELS START TO SATURATE BY 12Z THURSDAY BUT ABUNDANT DRY AIR IN THE
MID LEVELS WILL KEEP FROM THE NEED FOR PRECIPITATION CHANCES
WEDNESDAY NIGHT.
ON THURSDAY...THERE ARE STILL DISCREPANCIES AS TO HOW FAST THE COLD
AIR WILL MOVE IN. FOR EXAMPLE GFS ENSEMBLE MEMBERS VARY FROM 19F TO
42F FOR HIGHS AT KLBF. BECAUSE OF THESE DIFFERENCES STAYED FAIRLY
SIMILAR TO ONGOING FORECAST FOR HIGHS. WITH COLD AIR ADVECTION
THROUGH THE DAY...MAY SEE HIGHS EARLY WITH FALLING OR NEARLY STEADY
TEMPERATURES. IN TERMS OF PRECIPITATION FOR THURSDAY...THERE IS
AGREEMENT BETWEEN MODEL SOLUTIONS OF THE COLUMN BECOMING SATURATED
THURSDAY MORNING OVER THE NORTHERN PANHANDLE...AND WITH THE COLD AIR
ALREADY IN PLACE SHOULD START TO SEE SNOW IN THE MORNING HOURS. AS
THE ENTIRE COLUMN COOLS...WITH SOME LAYERS REACHING THE DENDRITIC
GROWTH ZONE...MIGHT GET SOME HIGHER SNOW TO LIQUID RATIO SNOWS UP
OVER NORTHWEST NEBRASKA. ACTUALLY...BY LATE THURSDAY NIGHT MOST OF
THE SOUNDING IS ISOTHERMAL IN THE DENDRITIC GROWTH ZONE.
HOWEVER...AT THIS POINT THE UPPER LEVEL SYSTEM IS WELL PAST AND THE
AREA IS IN AN AREA OF SUBSIDENCE AND LIFT IS MINIMAL SO THERE IS
ENOUGH DISCONNECT BETWEEN THE FAVORABLE CONDITIONS TO LIMIT FROM
HEAVY SNOWS. COULD SEE A COUPLE INCHES...POSSIBLY UP TO 4 ON THE
PINE RIDGE. WILL PROBABLY SEE SOME LIGHT SNOW ACROSS THE REST OF
NORTHERN NEBRASKA...BUT ONSET WILL BE LATER IN THE DAY THURSDAY AND
WITH THE UPWARD FORCING MOSTLY GONE BY MIDNIGHT EXPECT JUST LIGHT
AMOUNTS. DIFFERENT CONCERN IS FREEZING DRIZZLE FOR CENTRAL CHERRY
COUNTY AND EASTWARD ON THURSDAY. THE LOWEST 2500FT BECOME SATURATED
BY 18Z THURSDAY ACCORDING TO SOUNDINGS AT KVTN...WHILE A DEEP DRY
MID LAYER MAY PROHIBIT SEEDER FEEDER MECHANISM FROM OCCURRING FOR A
FEW HOURS. THERE IS DECENT OMEGA IN THESE LOW LEVELS SO DID ADD
CHANCES FOR FREEZING DRIZZLE INTO THE FORECAST FOR THURSDAY.
WILL ALSO BE QUITE WINDY ON THURSDAY AND THURSDAY NIGHT BEHIND THE
COLD FRONT WHICH WILL DROP WIND CHILLS TO AROUND -10F BY FRIDAY
MORNING.
LOOKING INTO THE WEEKEND...THE UPPER LOW OVER THE SOUTHWEST WILL
MIGRATE ACROSS THE SOUTHERN PLAINS WHILE THE LOCAL AREA WILL SEE
ANOTHER SHORTWAVE TROUGH MOVE ACROSS THE AREA THROUGH THE NORTHERN
STREAM. THERE IS SOME DIFFERENCES ON TIMING OF THIS NEXT
SYSTEM...BUT SHOULD BE MOVING THROUGH SOMETIME SATURDAY NIGHT/SUNDAY.
DOESN/T LOOK LIKE MUCH FOR PRECIPITATION WITH THIS NEXT SYSTEM BUT
THERE IS POTENTIAL FOR ANOTHER PUSH OF ARCTIC AIR INTO THE AREA
BEHIND IT.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z WEDNESDAY MORNING)
ISSUED AT 520 AM CST TUE DEC 17 2013
SFC LOW PRESSURE WILL TRACK ACROSS SRN CANADA TODAY AND TONIGHT. VFR
IS EXPECTED ALL AREAS WITH SCATTERED MID AND HIGH LEVEL CLOUDS.
&&
.LBF WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...CDC
LONG TERM...BROOKS
AVIATION...CDC
AREA FORECAST DISCUSSION
NWS NORTH PLATTE NE
356 AM CST TUE DEC 17 2013
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 355 AM CST TUE DEC 17 2013
THE THERMAL RIDGE WEAKENED A BIT WITH THE PASSAGE OF A WEAK COLD
FRONT TONIGHT. AS A RESULT...HIGH PRESSURE IS BUILDING THROUGH THE
NRN AND CNTL HIGH PLAINS ALLOWING FOR RADIATIONAL COOLING IN MOST
VALLEYS. THE RUC SHOWS LOW PRESSURE REFORMING ACROSS THE HIGH
PLAINS TODAY AND THIS SHOULD LIFT A WARM FRONT PART WAY THROUGH
THE FCST AREA. THE WARM FRONT WOULD LIKELY REACH HIGHWAY 183 BY
LATE AFTN.
FCST HIGHS FOLLOW THE WARMEST MODEL...THE HRRR FOR HIGHS NEAR 60
ACROSS THE SOUTHWEST WHERE THE THERMAL RIDGE WILL BE IN PLACE ALL
DAY. JUST SCATTERED HIGH CLOUDS ARE EXPECTED AS A SOLID BANK OF
CIRRUS IS OVER BRITISH COLUMBIA THIS AM.
THE RAP MODEL SHOWS WEST WINDS AT H850MB AT 15 TO 30KT AND THE MODEL
CONSENSUS 500M AGL WINDS ARE WEST AND SOUTHWEST AT 10 TO 20KT WHICH
WOULD PRODUCE 10 TO 20 MPH WINDS AT THE SFC.
LOWS TONIGHT VARY WIDELY WITH TEENS IN VALLEYS TO NEAR 30 ACROSS THE
SANDHILLS. A SHALLOW INVERSION SHOULD FORM GIVEN THE LIMITED HIGH
CLOUD COVER EXPECTED AND WESTERLY H850MB WINDS OF 20 TO 40KT. H850MB
TEMPS RISE IN THE TEENS ACROSS WRN NEB.
.LONG TERM...(WEDNESDAY THROUGH MONDAY)
ISSUED AT 355 AM CST TUE DEC 17 2013
PRIMARY CONCERNS FOR THIS FORECAST PERIOD ARE TEMPERATURES FOR
WEDNESDAY AND THURSDAY...AS WELL AS PRECIPITATION CHANCES AND
TYPES FOR THURSDAY AND THURSDAY NIGHT.
THE SHORTWAVE TROUGH CURRENTLY OVER THE GULF OF ALASKA WILL SPLIT
WEDNESDAY AND WEDNESDAY NIGHT WHICH WILL IMPACT THE LOCAL AREA IN
DIFFERENT WAYS. ONE PART OF THIS ENERGY WILL DIG SOUTH ALONG THE
WEST COAST WHICH WILL HELP THE THERMAL RIDGE BUILD OVER THE PLAINS.
THE SECOND PIECE OF ENERGY WILL STAY IN THE NORTHERN STREAM WHICH
WILL MOVE ACROSS THE PLAINS AS A WEAK SHORTWAVE TROUGH THURSDAY AND
THURSDAY NIGHT...WHICH WILL PUSH AN ARCTIC COLD FRONT ACROSS THE
FORECAST AREA.
STARTING ON WEDNESDAY...IS STILL A QUESTION TO HOW WARM IT WILL GET.
AS MENTIONED ABOVE THE THERMAL RIDGE BUILDS IN WITH ANOMALOUSLY WARM
AIR SEEN ALOFT. AT 18Z WEDNESDAY MODELS INDICATE 850MB TEMPERATURES
WILL HAVE RISEN BETWEEN 11C AND 15C ACROSS WESTERN AND NORTH CENTRAL
NEBRASKA. MODELS ARE ONLY MIXING THE BOUNDARY LAYER TO AROUND 875MB
SO DON/T REALIZE THE POTENTIAL WARMING. WINDS WILL BE FAIRLY LIGHT
WHICH WON/T HELP THE MIXING DEPTH...BUT DON/T THINK THE MODELS ARE
HANDLING THIS MIXING WELL AND IN MOST LOCATIONS WENT ABOVE MOST
GUIDANCE FOR HIGHS. MUCH OF THE NORTHERN TIER OF COUNTIES CONTINUES
TO HAVE SNOW ON THE GROUND WHICH AS OF MONDAY STILL HAD A STRONG
IMPACT ON TEMPERATURES AS HIGHS WERE ONLY IN THE LOW 40S...WITH
UPPER 50S AND LOW 60S OVER THE REST OF THE FORECAST AREA. SHOULD
HAVE CONTINUED MELTING TODAY...SO THE SNOW SHOULDN/T HAVE AS MUCH
IMPACT ON HIGHS...BUT WITH WET GROUND MAY NOT BE ABLE TO MIX TOO
MUCH SO CONTINUED THE TREND OF COOLER TEMPERATURES ACROSS THE NORTH.
THIS MAY NEED TO BE MODIFIED DEPENDING ON WHAT HIGHS DO TODAY.
COLD FRONT WILL PUSH SOUTH THROUGH THE FORECAST AREA WEDNESDAY
NIGHT...WITH THE COLDEST AIR LAGGING BEHIND THE FRONT. THE LOW
LEVELS START TO SATURATE BY 12Z THURSDAY BUT ABUNDANT DRY AIR IN THE
MID LEVELS WILL KEEP FROM THE NEED FOR PRECIPITATION CHANCES
WEDNESDAY NIGHT.
ON THURSDAY...THERE ARE STILL DISCREPANCIES AS TO HOW FAST THE COLD
AIR WILL MOVE IN. FOR EXAMPLE GFS ENSEMBLE MEMBERS VARY FROM 19F TO
42F FOR HIGHS AT KLBF. BECAUSE OF THESE DIFFERENCES STAYED FAIRLY
SIMILAR TO ONGOING FORECAST FOR HIGHS. WITH COLD AIR ADVECTION
THROUGH THE DAY...MAY SEE HIGHS EARLY WITH FALLING OR NEARLY STEADY
TEMPERATURES. IN TERMS OF PRECIPITATION FOR THURSDAY...THERE IS
AGREEMENT BETWEEN MODEL SOLUTIONS OF THE COLUMN BECOMING SATURATED
THURSDAY MORNING OVER THE NORTHERN PANHANDLE...AND WITH THE COLD AIR
ALREADY IN PLACE SHOULD START TO SEE SNOW IN THE MORNING HOURS. AS
THE ENTIRE COLUMN COOLS...WITH SOME LAYERS REACHING THE DENDRITIC
GROWTH ZONE...MIGHT GET SOME HIGHER SNOW TO LIQUID RATIO SNOWS UP
OVER NORTHWEST NEBRASKA. ACTUALLY...BY LATE THURSDAY NIGHT MOST OF
THE SOUNDING IS ISOTHERMAL IN THE DENDRITIC GROWTH ZONE.
HOWEVER...AT THIS POINT THE UPPER LEVEL SYSTEM IS WELL PAST AND THE
AREA IS IN AN AREA OF SUBSIDENCE AND LIFT IS MINIMAL SO THERE IS
ENOUGH DISCONNECT BETWEEN THE FAVORABLE CONDITIONS TO LIMIT FROM
HEAVY SNOWS. COULD SEE A COUPLE INCHES...POSSIBLY UP TO 4 ON THE
PINE RIDGE. WILL PROBABLY SEE SOME LIGHT SNOW ACROSS THE REST OF
NORTHERN NEBRASKA...BUT ONSET WILL BE LATER IN THE DAY THURSDAY AND
WITH THE UPWARD FORCING MOSTLY GONE BY MIDNIGHT EXPECT JUST LIGHT
AMOUNTS. DIFFERENT CONCERN IS FREEZING DRIZZLE FOR CENTRAL CHERRY
COUNTY AND EASTWARD ON THURSDAY. THE LOWEST 2500FT BECOME SATURATED
BY 18Z THURSDAY ACCORDING TO SOUNDINGS AT KVTN...WHILE A DEEP DRY
MID LAYER MAY PROHIBIT SEEDER FEEDER MECHANISM FROM OCCURRING FOR A
FEW HOURS. THERE IS DECENT OMEGA IN THESE LOW LEVELS SO DID ADD
CHANCES FOR FREEZING DRIZZLE INTO THE FORECAST FOR THURSDAY.
WILL ALSO BE QUITE WINDY ON THURSDAY AND THURSDAY NIGHT BEHIND THE
COLD FRONT WHICH WILL DROP WIND CHILLS TO AROUND -10F BY FRIDAY
MORNING.
LOOKING INTO THE WEEKEND...THE UPPER LOW OVER THE SOUTHWEST WILL
MIGRATE ACROSS THE SOUTHERN PLAINS WHILE THE LOCAL AREA WILL SEE
ANOTHER SHORTWAVE TROUGH MOVE ACROSS THE AREA THROUGH THE NORTHERN
STREAM. THERE IS SOME DIFFERENCES ON TIMING OF THIS NEXT
SYSTEM...BUT SHOULD BE MOVING THROUGH SOMETIME SATURDAY NIGHT/SUNDAY.
DOESN/T LOOK LIKE MUCH FOR PRECIPITATION WITH THIS NEXT SYSTEM BUT
THERE IS POTENTIAL FOR ANOTHER PUSH OF ARCTIC AIR INTO THE AREA
BEHIND IT.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z TUESDAY NIGHT)
ISSUED AT 1137 PM CST MON DEC 16 2013
OVER THE NEXT 24 HOURS...VFR CONDS ARE EXPECTED AT BOTH THE KVTN
AND KLBF TERMINALS. WINDS WILL BE FROM THE NORTHWEST AT UNDER 10
KTS OVERNIGHT TONIGHT...WITH A SHIFT IN WIND DIRECTION TO THE WEST
THEN SOUTHWEST THROUGH TUESDAY EVENING. SKIES WILL BE PARTLY TO
MOSTLY CLOUDY TONIGHT WITH CIGS AON 10000 FT AGL AT THE KVTN
TERMINAL...AND 20000 FT AGL AT THE KLBF TERMINAL. FOR
TUESDAY...CLEAR TO MOSTLY CLEAR SKIES ARE EXPECTED.
&&
.LBF WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...CDC
LONG TERM...BROOKS
AVIATION...CLB
AREA FORECAST DISCUSSION
NWS RALEIGH NC
300 AM EST WED DEC 17 2013
.SYNOPSIS...A POTENT UPPER LEVEL DISTURBANCE WILL DIG SOUTHEAST INTO
THE MID-ATLANTIC LATE THIS AFTERNOON AND EVENING...WHILE AN
ATTENDANT SURFACE LOW AND ASSOCIATED COLD FRONT TRACK QUICKLY EAST
ACROSS VIRGINIA AND THE CAROLINAS. MILD HIGH PRESSURE WILL BUILD
INTO THE REGION FROM THE SOUTHWEST TONIGHT AND WEDNESDAY...THEN
SHIFT OFFSHORE ON THURSDAY.
&&
.NEAR TERM /TONIGHT/...
AS OF 710 PM MONDAY...
THE LATEST WATER VAPOR IMAGERY SHOWED A WELL-DEFINED MID-LEVEL
SHORTWAVE MOVING TOWARD THE STATE FROM THE WEST...AND THIS WAVE WILL
MOVE ACROSS THE STATE THIS EVENING AND THROUGH THE EARLY PART OF THE
OVERNIGHT HOURS WITH AREAS OF MID- AND HIGH-LEVEL CLOUDS AHEAD OF
IT. THE LATEST RAP MID- AND UPPER-LEVEL RELATIVE HUMIDITY
FORECASTS...ALONG WITH THE HRRR WRF CLOUD COVER FORECAST...ARE
HANDLING THE BASIC COVERAGE AND ORIENTATION OF THE EXISTING CLOUDS
WELL...AND AS THE SHORTWAVE MOVES EAST THE CLOUDS...MOSTLY ALONG AND
NORTH OF ABOUT U.S. 64...WILL SHIFT EAST AS WELL. PATCHY HIGH CLOUDS
ARE LOCATED FARTHER UPSTREAM...AND IN THE WEST-TO-NORTHWEST FLOW
ALOFT SOME OF THESE SHOULD WORK THEIR WAY INTO THE NORTHWEST
PIEDMONT LATE TONIGHT. PARTLY CLOUDY THIS EVENING WITH PERIODS OF
MOSTLY CLEAR CONDITIONS OVERNIGHT BASICALLY ALONG AND NORTH OF U.S.
64...BECOMING PARTLY CLOUDY AGAIN LATE TOWARD THE TRIAD. SOUTH OF
ABOUT U.S. 64...MOSTLY CLEAR ON AVERAGE.
SURFACE DEW POINTS IN THE MID 30S TO NEAR 40 OVER A LARGE PART OF
CENTRAL NORTH CAROLINA...EXCEPT THE NORTHWEST PIEDMONT...HAVE
STARTED TO FALL OVER THE LAST HOUR OR TWO IN ACCORDANCE WITH THE RAP
FORECASTS AND MOS GUIDANCE. TEMPERATURES IN SOME AREAS HAVE SHOWN A
RAPID DECLINE...BUT OVERNIGHT THE SURFACE DEW POINTS ARE EXPECTED TO
STABILIZE AND THERE IS FORECAST A GRADUAL INCREASE IN 925MB WINDS AS
THE SURFACE HIGH MOVES OFF TO THE EAST...AND THE GRADIENT STARTS TO
TIGHTEN SOME. THE SURFACE FRONT TO OUR NORTH MAY MOVE A LITTLE
FARTHER NORTH LATE TONIGHT...AND THERE COULD BE JUST ENOUGH STIRRING
OF THE WIND OVERNIGHT AT TIMES TO KEEP TEMPERATURES FROM FALLING
WELL BELOW GUIDANCE. MINS ARE ALREADY FORECAST NEAREST THE COLDER
MAV GUIDANCE AND HAVE CONTINUED THAT FOR THIS FORECAST BASED ON
EXPECTED CLEARING AND THE PACE OF FALLING TEMPERATURES THUS FAR.
&&
.SHORT TERM /WEDNESDAY AND WEDNESDAY NIGHT/...
AS OF 240 PM MONDAY...
THE SURFACE LOW TRACKING EASTWARD THROUGH THE NORTHERN MID-ATLANTIC
STATES WILL EXIT OFFSHORE TUESDAY AFTERNOON...AND WILL DRAG A
SURFACE COLD FRONT THROUGH THE AREA TUESDAY EVENING. UNDER PARTLY TO
MOSTLY SUNNY SKIES...LOW-LEVEL SWLY WARM AIR ADVECTION PRIOR TO THE
ARRIVAL OF THE COLD FRONT WILL ALLOW THICKNESSES TO CLIMB ANOTHER 10
METERS WHICH SHOULD SUPPORT HIGHS IN THE MID 50S NORTH TO AROUND 60
SOUTH.
CAA IN THE WAKE OF THE COLD FRONTAL PASSAGE TUESDAY EVENING WILL
GOVERN OVERNIGHT LOWS...WITH LOW-LEVEL THICKNESSES PROGGED TO FALL
TO AROUND 1280 METERS...35 METERS BELOW NORMAL. OVERNIGHT LOWS IN
THE UPPER 20S NORTH TO LOWER/MID 30S SOUTHEAST.
&&
.LONG TERM /THURSDAY THROUGH MONDAY/...
AS OF 300 AM TUESDAY...
...RECORD WARMTH EXPECTED SATURDAY AND SUNDAY...
SEE THE CLIMATE SECTION BELOW FOR DAILY RECORD HIGHS FOR THE 21ST
AND 22ND OF DECEMBER.
STRONG UPPER RIDGING WILL SET UP OFF THE SE COAST FRI-SUN. THIS WILL
BLOCK THE COLD FRONT TO OUR WEST THROUGH LATE SUNDAY OR SUNDAY NIGHT
PER THE FAVORED AND SLOWER EC GUIDANCE. THIS IS ALSO WHEN THE CHANCE
OF RAIN IS EXPECTED.
UNTIL THEN... A GRADUAL WARMING TREND THURSDAY AND FRIDAY WITH
TEMPERATURES BECOMING ABOVE NORMAL BY THURSDAY WHEN HIGHS WILL REACH
THE LOWER TO MID 60S WITH MOSTLY SUNNY SKIES AND A SW BREEZE. FRIDAY
HIGHS SHOULD APPROACH 70 AND EVEN HIT 70 IN THE SANDHILLS.
BY SATURDAY... LOW CLOUDS SHOULD MIX OUT BY NOON MOST AREAS. THE
INCREASING LOW LEVEL FLOW SHOULD ALSO ALLOW TEMPERATURES TO SOAR
INTO THE LOWER TO MID 70S. IF THIS OCCURS... NEW DAILY RECORD HIGHS
WOULD BE LIKELY.
IT APPEARS THAT THE ONLY THING THAT MAY SLOW THE TEMPERATURES THIS
WEEKEND WOULD POTENTIALLY BE LOW CLOUDINESS IN THE S-SW FLOW
PATTERN. HOWEVER... IT APPEARS THAT THE NW PIEDMONT WOULD BE THE
MOST LIKELY AREA TO HAVE THE LOW CLOUDS LINGER MUCH OF THE DAY
SUNDAY. HOWEVER... THE COOLEST GUIDANCE STILL GIVES LOWER 70S AT
GREENSBORO AND MID 70S IN RALEIGH SUNDAY... WHICH WOULD BE RIGHT AT
THE RECORD DAILY RECORDS OF 71 AND 75.
BY LATE SUNDAY INTO MONDAY... INCREASING POP WITH THE ACTUAL COLD
FRONT EXPECTED TO PUSH SE THROUGH THE REGION MONDAY. TEMPS ON MONDAY
SHOULD COOL OFF DUE TO THE WIND SHIFT TO THE NE AND THE EXPECTED
RAINFALL.
BY TUESDAY... HIGHS SHOULD RETURN BACK INTO THE LOWER TO MID 50S
(NEAR NORMAL) AS A STRONG HIGH PRESSURE BUILDS DOWN THE EASTERN
SEABOARD.
THE OUTLOOK FOR NEXT WEEK... IS FOR MUCH COOLER TEMPERATURES WITH A
CHANCE OF COLD RAIN AGAIN MID WEEK WITH ADDITIONAL WAVES POSSIBLE
ALONG THE SE COAST.
&&
.AVIATION /06Z TUESDAY THROUGH SATURDAY/...
AS OF 100 AM TUESDAY...
24-HR TAF PERIOD: THE LATEST MODEL GUIDANCE HAS TRENDED FURTHER
SOUTH WITH A POTENT UPPER LEVEL DISTURBANCE DIGGING SE INTO THE MID-
ATLANTIC TODAY/TONIGHT...ALONG WITH THE ATTENDANT CLIPPER LOW NOW
PROGGED TO TRACK EAST ACROSS THE VIRGINIAS. AS A RESULT...IT NOW
APPEARS THAT THERE WILL BE A NARROW WINDOW OF OPPORTUNITY FOR MVFR
CEILINGS AND ISOLD SHOWER ACTIVITY BETWEEN 00-06Z WED...PRIMARILY
ALONG AND NORTH OF HWY 64 (INT/GSO/RDU/RWI TERMINALS). OTHERWISE...
VFR CONDITIONS WILL PREVAIL. SW WINDS AT 5-10 KT THIS MORNING WILL
INCREASE TO 10-15 KT BY MID AFTERNOON WITH A POTENTIAL FOR GUSTS IN
THE 18-23 KT RANGE...ESPECIALLY AT THE FAY/RWI TERMINALS (MORE-SO
FAY) WHERE THE MSLP GRADIENT WILL BE TIGHTEST. WINDS WILL VEER TO
THE WNW/NW AT 10-15 KT BETWEEN 00-06Z WED AS A COLD FRONT ASSOC/W
THE CLIPPER LOW SWEEPS EAST ACROSS CENTRAL NC.
LOOKING AHEAD: VFR CONDITIONS WILL RULE WED/WED NIGHT IN THE WAKE OF
THE FRONT AS MILD HIGH PRESSURE BUILDS INTO THE REGION FROM THE
SOUTHWEST. HIGH PRESSURE WILL MOVE OFFSHORE BY LATE THU...SETTING UP
AN INCREASINGLY WARM/MOIST SOUTHERLY RETURN FLOW ACROSS THE
CAROLINAS THU-SAT. VFR CONDITIONS WILL LARGELY PREVAIL THROUGH THIS
PERIOD...THOUGH WITH AN INCREASING CHANCE OF IFR/LIFR CEILINGS
DURING THE EARLY MORNING HOURS FRI/SAT AND POSSIBLY A CHANCE OF
SHOWERS OVER THE WEEKEND. -VINCENT
&&
.CLIMATE...
DAILY RECORD HIGHS FOR SATURDAY AND SUNDAY... DECEMBER 21 AND 22
ARE...
RALEIGH/DURHAM...
DECEMBER 21... 71 DEGREES... SET IN 1967
DECEMBER 22... 75 DEGREES... SET IN 1967
GREENSBORO...
DECEMBER 21... 66 DEGREES... SET IN 1923
DECEMBER 22... 71 DEGREES... SET IN 1923
&&
.RAH WATCHES/WARNINGS/ADVISORIES...
NONE
&&
$$
SYNOPSIS...VINCENT
NEAR TERM...VINCENT
SHORT TERM...CBL
LONG TERM...BADGETT
AVIATION...VINCENT
AREA FORECAST DISCUSSION
NWS RALEIGH NC
113 AM EST WED DEC 17 2013
.SYNOPSIS...A POTENT UPPER LEVEL DISTURBANCE WILL DIG SOUTHEAST INTO
THE MID-ATLANTIC LATE THIS AFTERNOON AND EVENING...WHILE AN
ATTENDANT SURFACE LOW AND ASSOCIATED COLD FRONT TRACK QUICKLY EAST
ACROSS VIRGINIA AND THE CAROLINAS. MILD HIGH PRESSURE WILL BUILD
INTO THE REGION FROM THE SOUTHWEST TONIGHT AND WEDNESDAY...THEN
SHIFT OFFSHORE ON THURSDAY.
&&
.NEAR TERM /TONIGHT/...
AS OF 710 PM MONDAY...
THE LATEST WATER VAPOR IMAGERY SHOWED A WELL-DEFINED MID-LEVEL
SHORTWAVE MOVING TOWARD THE STATE FROM THE WEST...AND THIS WAVE WILL
MOVE ACROSS THE STATE THIS EVENING AND THROUGH THE EARLY PART OF THE
OVERNIGHT HOURS WITH AREAS OF MID- AND HIGH-LEVEL CLOUDS AHEAD OF
IT. THE LATEST RAP MID- AND UPPER-LEVEL RELATIVE HUMIDITY
FORECASTS...ALONG WITH THE HRRR WRF CLOUD COVER FORECAST...ARE
HANDLING THE BASIC COVERAGE AND ORIENTATION OF THE EXISTING CLOUDS
WELL...AND AS THE SHORTWAVE MOVES EAST THE CLOUDS...MOSTLY ALONG AND
NORTH OF ABOUT U.S. 64...WILL SHIFT EAST AS WELL. PATCHY HIGH CLOUDS
ARE LOCATED FARTHER UPSTREAM...AND IN THE WEST-TO-NORTHWEST FLOW
ALOFT SOME OF THESE SHOULD WORK THEIR WAY INTO THE NORTHWEST
PIEDMONT LATE TONIGHT. PARTLY CLOUDY THIS EVENING WITH PERIODS OF
MOSTLY CLEAR CONDITIONS OVERNIGHT BASICALLY ALONG AND NORTH OF U.S.
64...BECOMING PARTLY CLOUDY AGAIN LATE TOWARD THE TRIAD. SOUTH OF
ABOUT U.S. 64...MOSTLY CLEAR ON AVERAGE.
SURFACE DEW POINTS IN THE MID 30S TO NEAR 40 OVER A LARGE PART OF
CENTRAL NORTH CAROLINA...EXCEPT THE NORTHWEST PIEDMONT...HAVE
STARTED TO FALL OVER THE LAST HOUR OR TWO IN ACCORDANCE WITH THE RAP
FORECASTS AND MOS GUIDANCE. TEMPERATURES IN SOME AREAS HAVE SHOWN A
RAPID DECLINE...BUT OVERNIGHT THE SURFACE DEW POINTS ARE EXPECTED TO
STABILIZE AND THERE IS FORECAST A GRADUAL INCREASE IN 925MB WINDS AS
THE SURFACE HIGH MOVES OFF TO THE EAST...AND THE GRADIENT STARTS TO
TIGHTEN SOME. THE SURFACE FRONT TO OUR NORTH MAY MOVE A LITTLE
FARTHER NORTH LATE TONIGHT...AND THERE COULD BE JUST ENOUGH STIRRING
OF THE WIND OVERNIGHT AT TIMES TO KEEP TEMPERATURES FROM FALLING
WELL BELOW GUIDANCE. MINS ARE ALREADY FORECAST NEAREST THE COLDER
MAV GUIDANCE AND HAVE CONTINUED THAT FOR THIS FORECAST BASED ON
EXPECTED CLEARING AND THE PACE OF FALLING TEMPERATURES THUS FAR.
&&
.SHORT TERM /TUESDAY AND TUESDAY NIGHT/...
AS OF 240 PM MONDAY...
THE SURFACE LOW TRACKING EASTWARD THROUGH THE NORTHERN MID-ATLANTIC
STATES WILL EXIT OFFSHORE TUESDAY AFTERNOON...AND WILL DRAG A
SURFACE COLD FRONT THROUGH THE AREA TUESDAY EVENING. UNDER PARTLY TO
MOSTLY SUNNY SKIES...LOW-LEVEL SWLY WARM AIR ADVECTION PRIOR TO THE
ARRIVAL OF THE COLD FRONT WILL ALLOW THICKNESSES TO CLIMB ANOTHER 10
METERS WHICH SHOULD SUPPORT HIGHS IN THE MID 50S NORTH TO AROUND 60
SOUTH.
CAA IN THE WAKE OF THE COLD FRONTAL PASSAGE TUESDAY EVENING WILL
GOVERN OVERNIGHT LOWS...WITH LOW-LEVEL THICKNESSES PROGGED TO FALL
TO AROUND 1280 METERS...35 METERS BELOW NORMAL. OVERNIGHT LOWS IN
THE UPPER 20S NORTH TO LOWER/MID 30S SOUTHEAST.
&&
.LONG TERM /WEDNESDAY THROUGH MONDAY/...
AS OF 300 PM MONDAY...
A PROGRESSIVE NORTHERN STREAM SHORT WAVE TROUGH EXITS THE MID
ATLANTIC EARLY ON WEDNESDAY WITH THE FLOW ALOFT BECOMING MORE
WESTERLY ON THURSDAY. A DRY ATMOSPHERE WITH PW VALUES GENERALLY LESS
THAN 0.3 INCHES PROVIDES A HIGH CONFIDENCE FORECAST OF DRY WEATHER
WITH FEW CLOUDS. SLIGHTLY BELOW NORMAL TEMPS ON WEDNESDAY WITH HIGHS
AROUND 50 WILL WARM INTO THE MID 50S TO NEAR 60 BY THURSDAY. LOWS
THURSDAY MORNING WILL RANGE IN THE UPPER 20S TO LOWER 30S.
AN AMPLIFYING TROUGH DIVES SOUTH ALONG THE PACIFIC COAST ON FRIDAY
AS THE FLOW ALOFT OVER CENTRAL NC BECOMES MORE SOUTHWESTERLY. AT THE
SAME TIME SURFACE HIGH PRESSURE OVER THE CAROLINAS SHIFTS OFFSHORE
AND A LOW LEVEL RETURN FLOW DEVELOPS. THE RETURN FLOW WILL ALLOW
SHALLOW MOISTURE TO SPREAD INTO THE REGION...MODERATING MORNING LOWS
ON FRIDAY (IN THE 40-45 RANGE) AND PROVING THE POTENTIAL FOR SOME
MORNING STRATUS THAT WILL MIX INTO SOME AFTERNOON CUMULIFORM CLOUDS
UNDER A CANOPY OF CIRRUS ALOFT. COULD BE AN ISOLATED SHOWER IN THE
WARM SOUTHERLY FLOW BUT THIS PATTERN IS SOMETIMES SLOW TO EVOLVE AND
COVERAGE WILL LIKELY BE LIMITED. GIVEN LOW CONFIDENCE IN
POPS...PREFER TO OMIT RAIN CHANCES ON FRIDAY FOR NOW. HIGHS FRIDAY
AFTERNOON SHOULD CLIMB INTO THE 60S TO NEAR 70 WITH LOWS FRIDAY
NIGHT IN THE LOWER TO MID 50S.
THE PACIFIC TROUGH CLOSES OFF LATE FRIDAY INTO EARLY SATURDAY IN
MEXICO SOUTH OF AZ/NM AND THEN LIFTS NORTHEAST ACROSS THE
CENTRAL/EASTERN U.S. OVER THE WEEKEND INTO MONDAY. THE MAIN ENERGY
WITH THE SYSTEM SLOWLY SHEARS OUT OVER THE MS VALLEY INTO THE
WESTERN OH VALLEY AND GREAT LAKES WITH THE ATTENDANT SURFACE LOW
REMAINING WEST OF THE APPALACHIANS. THE TRAILING COLD FRONT IS LEFT
DANGLING SOUTH OF THE DEPARTING STRONGER FLOW AND SETS UP PARALLEL
TO THE FLOW ALOFT. THIS TYPE OF PATTERN TYPICALLY RESULTS IN A
SLOWER PASSAGE OF THE COLD FRONT AND LESS ROBUST PRECIPITATION
CHANCES. WPC GUIDANCE PREFERS A SLOWER EC ENS MEAN AND HAVE REDUCED
POPS SLIGHTLY BUT MORE SIGNIFICANTLY DELAYED POPS A BIT FOCUSING ON
LATER MONDAY FOR THE BEST CHANCE OF SHOWERS. -BLAES
&&
.AVIATION /06Z TUESDAY THROUGH SATURDAY/...
AS OF 100 AM TUESDAY...
24-HR TAF PERIOD: THE LATEST MODEL GUIDANCE HAS TRENDED FURTHER
SOUTH WITH A POTENT UPPER LEVEL DISTURBANCE DIGGING SE INTO THE MID-
ATLANTIC TODAY/TONIGHT...ALONG WITH THE ATTENDANT CLIPPER LOW NOW
PROGGED TO TRACK EAST ACROSS THE VIRGINIAS. AS A RESULT...IT NOW
APPEARS THAT THERE WILL BE A NARROW WINDOW OF OPPORTUNITY FOR MVFR
CEILINGS AND ISOLD SHOWER ACTIVITY BETWEEN 00-06Z WED...PRIMARILY
ALONG AND NORTH OF HWY 64 (INT/GSO/RDU/RWI TERMINALS). OTHERWISE...
VFR CONDITIONS WILL PREVAIL. SW WINDS AT 5-10 KT THIS MORNING WILL
INCREASE TO 10-15 KT BY MID AFTERNOON WITH A POTENTIAL FOR GUSTS IN
THE 18-23 KT RANGE...ESPECIALLY AT THE FAY/RWI TERMINALS (MORE-SO
FAY) WHERE THE MSLP GRADIENT WILL BE TIGHTEST. WINDS WILL VEER TO
THE WNW/NW AT 10-15 KT BETWEEN 00-06Z WED AS A COLD FRONT ASSOC/W
THE CLIPPER LOW SWEEPS EAST ACROSS CENTRAL NC.
LOOKING AHEAD: VFR CONDITIONS WILL RULE WED/WED NIGHT IN THE WAKE OF
THE FRONT AS MILD HIGH PRESSURE BUILDS INTO THE REGION FROM THE
SOUTHWEST. HIGH PRESSURE WILL MOVE OFFSHORE BY LATE THU...SETTING UP
AN INCREASINGLY WARM/MOIST SOUTHERLY RETURN FLOW ACROSS THE
CAROLINAS THU-SAT. VFR CONDITIONS WILL LARGELY PREVAIL THROUGH THIS
PERIOD...THOUGH WITH AN INCREASING CHANCE OF IFR/LIFR CEILINGS
DURING THE EARLY MORNING HOURS FRI/SAT AND POSSIBLY A CHANCE OF
SHOWERS OVER THE WEEKEND. -VINCENT
&&
.RAH WATCHES/WARNINGS/ADVISORIES...
NONE
&&
$$
SYNOPSIS...VINCENT
NEAR TERM...DJF
SHORT TERM...CBL
LONG TERM...BLAES
AVIATION...VINCENT
AREA FORECAST DISCUSSION
NWS BISMARCK ND
226 AM CST TUE DEC 17 2013
.UPDATE...
ISSUED AT 225 AM CST TUE DEC 17 2013
QUICK UPDATE TO ISSUE A WIND ADVISORY FROM THE TURTLE MOUNTAINS
SOUTH INTO THE NORTHERN PORTION OF THE JAMES RIVER VALLEY. EXPECT
SUSTAINED WINDS TO 35 MPH WITH GUSTS TO 45 MPH. UPDATES TO TEXT
PRODUCTS FORTHCOMING.
UPDATE ISSUED AT 1154 PM CST MON DEC 16 2013
LATEST WATER VAPOR IMAGERY SHOWS NORTHWEST FLOW INTO NORTH DAKOTA
WITH ONE SHORTWAVE EXITING THE SOUTHWEST...WITH ANOTHER SHORTWAVE
NEAR THE TURTLE MOUNTAINS MOVING SOUTHEAST WITH TIME. LOCAL/REGIONAL
RADAR SHOWS ISOLATED PRECIPITATION AREAS WHICH CONTINUE TO MOVE
SOUTHEAST AND WEAKEN. THUS HAVE MAINTAINED THE TREND OF ENDING ANY
MEASURABLE PRECIPITATION AMOUNTS ACROSS THE SOUTHWEST AND JAMES
RIVER VALLEY OVER THE NEXT ONE TO THREE HOURS. WINDS WILL REMAIN
GUSTY OVERNIGHT...ESPECIALLY NORTH AND EAST CENTRAL. WILL KEEP THE
SPECIAL WEATHER STATEMENT GOING UNTIL 130 AM CST MENTIONING ICY
TRAVEL. REST OF FORECAST LOOKS IN GOOD SHAPE OVERNIGHT.
UPDATE ISSUED AT 932 PM CST MON DEC 16 2013
MAIN UPDATE THIS EVENING WAS TO BUMP UP POPS THROUGH MIDNIGHT OVER
THE SOUTHWEST. BAND OF LIGHT SNOW INDUCED BY A SHORTWAVE IN
NORTHWEST UPPER FLOW HAD DEVELOPED FROM NEAR BEACH SOUTHWEST TO
AROUND HETTINGER. THIS BAND SHOULD MOVE QUICKLY SOUTHEAST BUT WILL
PRODUCE PERIODS OF LIGHT TO MODERATE SNOW. WINDS HAVE DIMINISHED
OVER THE SOUTHWEST SO NOT MUCH PROBLEM WITH BLOWING SNOW HERE.
THINK SNOW WILL BE PRETTY MUCH OUT OF THE AREA AROUND MIDNIGHT.
ELSEWHERE...STRONG WINDS CONTINUE OVER CENTRAL NORTH DAKOTA WITH
GUSTS TO 35 MPH AT MINOT AND BISMARCK EAST TO RUGBY...CARRINGTON
AND JAMESTOWN. EXPECT AREAS OF BLOWING AND DRIFTING SNOW TO
CONTINUE THROUGH LATE TONIGHT. ISOLATED SNOW SHOWERS FROM
CARRINGTON TO JAMESTOWN WILL MOVE QUICKLY SOUTHEAST...HOWEVER A
BRIEF FLURRY OR SNOW SHOWER CANNOT BE COMPLETELY RULED OUT MOST
ANYWHERE THROUGH LATE THIS EVENING.
UPDATE ISSUED AT 644 PM CST MON DEC 16 2013
LATEST RADAR LOOP IS STILL SHOWING SOME LIGHT REFLECTIVITIES
ACROSS WESTERN AND CENTRAL NORTH DAKOTA...BUT LITTLE IN THE WAY OF
SURFACE REPORTS VIA OBSERVATIONS OR WEATHER CAMERAS. STILL KEPT
SOME POPS IN THE SOUTHWEST...HIGHEST EARLY THIS EVENING AND
TAPERING THROUGH LATE EVENING. ALSO SOME SNOW SHOWERS OVER ROLETTE
COUNTY SO BUMPED UP POPS OVER NORTHEAST ROLETTE FOR A COUPLE
HOURS. RAISED SKY COVER OVER THE SOUTHWEST AND GENERALLY BUMPED UP
SKY ACROSS THE AREA THROUGH THE EVENING AS THERE ARE QUITE A BIT
OF MID AND HIGH LEVEL CLOUDS TRAVERSING THE AREA IN NORTHWEST
FLOW.
RECEIVED QUITE A FEW RESPONSES VIA SOCIAL MEDIA ABOUT THE
SLIPPERY ROADS ACROSS MAINLY THE NORTH. WILL EXTEND THE SPS FOR
ICY CONDITIONS THROUGH THE EVENING HOURS AS WE WILL REMAIN BREEZY
AND TEMPERATURES DROP BELOW FREEZING.
&&
.SHORT TERM...(THIS AFTERNOON THROUGH TUESDAY AFTERNOON)
ISSUED AT 334 PM CST MON DEC 16 2013
FORECAST HIGHLIGHTS IN THE SHORT TERM PERIOD WILL BE AREAS OF
BLOWING/DRIFTING SNOW RESULTING IN POSSIBLE ICY ROADS/BLACK ICE
ACROSS THE NORTH THROUGH THIS EVENING...AND A CHANCE OF LIGHT SNOW
THIS AFTERNOON AND EVENING WEST TO EAST.
CURRENTLY...STRONG NORTHWEST FLOW ALOFT WITH A SHARP RIDGE OFF
THE WEST COAST AND A BROAD LONG WAVE TROUGH OVER THE EASTERN
UNITED STATES. UPPER LEVEL JET STREAM EXTENDS FROM THE TOP OF THE
RIDGE OVER ALASKA...SOUTHEAST INTO THE NORTHERN HIGH PLAINS OF
MT/WY. STRONG PRESSURE GRADIENT CONTINUES TO DEVELOP ACROSS WEST
AND CENTRAL NORTH DAKOTA WEST OF A SURFACE TROUGH OVER FAR WESTERN
MINNESOTA. GRADIENT FORCING WILL INCREASE THROUGHOUT THE DAY AND
INTO THIS EVENING AS THE TROUGH REMAINS QUASI-STATIONARY AND AS A
SURFACE HIGH BUILDS OFF TO OUR WEST CENTERED OVER THE NORTHEASTERN
SNAKE RIVER VALLEY OF EASTERN IDAHO.
MODELS EARLIER WERE LOOKING LIKE THEY WERE TRENDING TOWARDS A
CONSENSUS REGARDING PRECIPITATION CHANCES THIS AFTERNOON AND
EVENING. NOW NOT SO MUCH. MOISTURE IS HAVING A HARD TIME REACHING
THE GROUND ACROSS MY WEST CENTRAL. WEB CAMS OVER SOUTHWEST NORTH
DAKOTA DEFINITELY SHOWING SNOWFALL ALTHOUGH MOSTLY MELTING ON THE
ROAD SURFACES. BOWMAN RADAR STILL LIT UP...AND BAKER MT STILL
REPORTING SNOW. THE 12Z ECMWF AND LATEST RAP SEEM TO BE CAPTURING
REALITY THE BEST VERSUS OTHER GUIDANCE. LEANED IN THEIR DIRECTION
WITH LINGERING LIGHT PRECIPITATION SOUTHWEST NOW THROUGH THIS
EVENING...AND ANOTHER AREA OF LIGHT PRECIPITATION MOVING SOUTHEAST
OVER MY EASTERN COUNTIES LATE AFTERNOON AND EVENING. THIS AREA
CURRENTLY SHOWING UP ON RADAR OVER SOUTHEAST SK/SOUTHWEST
MANITOBA.
THE INCREASING PRESSURE GRADIENT WILL SEE WINDS INCREASE TO JUST
BELOW WIND ADVISORY CRITERIA MOST LOCATIONS NOW THROUGH THE
EVENING HOURS...BEFORE WINDING DOWN AFTER 06Z. AT THIS TIME WINDS
ARE SUSTAINED AT 15-25 MPH MOST LOCATIONS...WITH GUSTS AS HIGH AS
35 MPH REPORTED. ROAD SFC TEMPS REMAIN AT OR BELOW FREEZING NORTH
AND ABOVE 32F SOUTH. AIR TEMPERATURES MAINLY IN THE LOWER TO MID
30S. WIND DRIVEN SNOW IS STILL EXPECTED TO CREATE HAZARDOUS
TRAVEL...ESPECIALLY WHEN WET ROADS REFREEZE AND/OR BLOWING SNOW
STARTS TO STICK THIS AFTERNOON. WILL MAINTAIN THE SPECIAL WEATHER
STATEMENT AS IS FOR NOW AND LET THE EVENING CREW DECIDE ITS FATE
AT THE 7PM UPDATE PERIOD.
TUESDAY MORNING/AFTERNOON LOOK TO BE RELATIVELY QUIET WITH PARTLY
CLOUDY SKIES AND DRY CONDITIONS. A WARM FRONT MOVING INTO
SOUTHEAST MONTANA WILL SEE TEMPERATURES WARMING TO NEAR 40 OVER MY
FAR SOUTHWEST CORNER. SHARP TEMPERATURE GRADIENT WITH HIGHS AROUND
15 ABOVE FOR THE TURTLE MOUNTAINS.
.LONG TERM...(TUESDAY NIGHT THROUGH MONDAY)
ISSUED AT 334 PM CST MON DEC 16 2013
THE MAIN FORECAST ISSUE IS SNOWFALL AMOUNTS AND COVERAGE WITH THE
MID WEEK STORM.
A LOW PRESSURE CLIPPER SYSTEM IS FORECAST TO DEVELOP TUESDAY OVER
ALBERTA AND MOVE EAST/SOUTHEAST TOWARDS NORTH DAKOTA TUESDAY NIGHT.
WINDS ACROSS THE FORECAST AREA SHOULD START OUT SOUTHERLY EARLY
TUESDAY EVENING...BECOMING WEST DURING THE EVENING/NIGHT WITH WARM
ADVECTION AS NORTH DAKOTA REMAINS IN THE WARM SECTOR OF THE SYSTEM.
ON WEDNESDAY THE CLIPPER LOW DEVELOPS INTO MORE OF A COLD FRONT IN
NATURE...MOVING SOUTH ACROSS THE STATE. IT APPEARS THAT THE MARKED
COLD ADVECTION WITH THE ARCTIC AIR BEGINS WEDNESDAY AROUND NOON IN
THE NORTH AND DURING THE AFTERNOON FARTHER SOUTH. HIGHS WEDNESDAY
SHOULD RANGE FROM THE UPPER TEENS/MID 20S NORTH TO THE UPPER 20S/30S
SOUTH. KEPT A SLIGHT CHANCE OF LIGHT SNOW IN THE NORTHWEST AND NORTH
CENTRAL NORTH DAKOTA ALONG THE ARCTIC COLD FRONT.
MODEL AGREEMENT CONTINUES TO IMPROVE REGARDING THE MAIN SYNOPTIC
FEATURES OF THE UPPER LEVEL TROUGH AND VORT ENERGY IMPULSES...AS
WELL AS THE POSITION OF THE COLD FRONT AND ARCTIC HIGH PRESSURE
SYSTEM. THE UPPER LEVEL TROUGH MOVES ACROSS NORTH DAKOTA
THURSDAY/THURSDAY EVENING. MEANWHILE THE SURFACE ARCTIC HIGH DIVES
SOUTH FROM ALBERTA INTO MONTANA WEDNESDAY NIGHT/THURSDAY. IN NORTH
DAKOTA...THE ARCTIC COLD FRONT MOVES SOUTH ACROSS THE STATE
WEDNESDAY AFTERNOON/EVENING WITH COLD ADVECTION CONTINUING THROUGH
THE DAY THURSDAY.
THE PLACEMENT OF SNOWFALL LOOKS TO BE HIGHEST IN MONTANA...BUT SNOW
ACCUMULATIONS ALONG THE NORTH DAKOTA/SOUTH DAKOTA BORDER SHOULD BE
IN THE 2-4 INCH RANGE. FOR WESTERN AND CENTRAL NORTH DAKOTA THE BULK
OF THE SNOWFALL SHOULD BEGIN WEDNESDAY NIGHT IN THE WEST...AND
EXPAND INTO CENTRAL NORTH DAKOTA AFTER MIDNIGHT WEDNESDAY
NIGHT/DAYBREAK THURSDAY MORNING...CONTINUE FOR MUCH OF THE
DAY THURSDAY...BEFORE TAPERING OFF IN THE JAMES RIVER VALLEY
THURSDAY EVENING.
VERY COLD AIR WILL ACCOMPANY THIS STORM SYSTEM WEDNESDAY NIGHT
THROUGH SATURDAY. SOME AREAS...ESPECIALLY THE NORTH...MAY HIT WIND
CHILL ADVISORY CRITERIA WEDNESDAY NIGHT AND THURSDAY NIGHT.
THE UPPER LEVEL PATTERN THROUGH THE WEEKEND CONTINUES NORTHWEST FLOW
ALOFT WITH A LARGE HUDSON BAY LOW IN PLACE. TOWARDS THE BEGINNING OF
NEXT WEEK THE MODELS ARE HINTING AT A MORE PROGRESSIVE PATTERN WITH
A WESTERN RIDGE BUILDING AND PUSHING THE HUDSON BAY LOW EASTWARD. NO
BIG WARM-UPS BUT NO BIG ARCTIC OUTBREAKS EITHER.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z TUESDAY NIGHT)
ISSUED AT 1154 PM CST MON DEC 16 2013
VFR CIGS/VSBYS NEXT 24HR. GUSTY WEST TO NORTHWEST WINDS OF 20KT TO
30KT WILL DECREASE TO AROUND 15KT BETWEEN 12Z AND 15Z TUESDAY.
OVERALL EXPECT MID LEVEL (8KFT-10KFT) SCT/BKN CONDITIONS AS
ANOTHER WARM FRONT APPROACHES TUESDAY AFTERNOON AND EVENING.
HOWEVER NO PRECIPITATION IS EXPECTED WITH IT.
&&
.BIS WATCHES/WARNINGS/ADVISORIES...
WIND ADVISORY UNTIL 7 AM CST THIS MORNING FOR NDZ004-005-012-013-
023-025-037.
&&
$$
UPDATE...KS
SHORT TERM...NH
LONG TERM...JV
AVIATION...KS
AREA FORECAST DISCUSSION
NWS GRAND FORKS ND
1148 PM CST MON DEC 16 2013
.UPDATE...
ISSUED AT 1148 PM CST MON DEC 16 2013
CURRENT FCST APPEARS TO BE ON TRACK WITH SNOW SHOWERS NOW ENTERING
FAR EASTERN EDGE OF RADAR COVERAGE...HOWEVER BJI REPORTING LIGHT
SNOW. MAY ACTUALLY END AN HOUR EARLIER THAN CURRENT GRIDS SHOW.
DID USE THE NAM H850-H700 RH FIELD TO FINE TUNE SKY COVER TONIGHT.
THERE IS A 5K FT DEC OVER PORTIONS OF MANITOBA THAT WILL ROTATE
DOWN AND CLIP NORTHEASTERN PORTIONS OF CWA. HAVE KEPT SCT SHSN IN
THE FCST AFT 09Z AS WINNIPEG AND SURROUNDING AREAS ARE RECEIVING
SOME LIGHT SNOW. CONTINUED LAPS TRENDS FOR OVERNIGHT LOWS.
UPDATE ISSUED AT 930 PM CST MON DEC 16 2013
CURRENT RADAR SHOWING SNOW SHOWERS HAVE CLEARED MOST OF EASTERN ND
WITH EXCEPTION OF A SMALLER BATCH AROUND AND NORTH OF VALLEY CITY.
AS PER RUC...APPEARS SHOWERS ARE INTENSIFY SLIGHTLY SO KEPT SNOW
TOTALS IN THE HALF TO ONE INCH RANGE DESPITE RECEIVING VERY LITTLE
HERE IN GRAND FORKS. MAY SEE A LITTLE BETTER ACCUMULATION FROM
FOSSTON DOWN THROUGH PARK RAPIDS. ADJUSTED NORTHWARD THE LIKELY
POPS BASED ON LATEST TRENDS AND BEGAN LOWERING/REMOVING EARLIER
THE POPS WEST OF THE RIVER. RUC CONTINUES TO BRING A SECOND ROUND
OF LIGHT SHOWERS TO MY FAR NORTHEAST AND DID BRING IN SCATTERED
SHOWERS AFT 09Z FOR ROSEAU/LAKE OF THE WOODS. ALSO PUT PATCHY BLOWING
SNOW IN GRIDS FOR MOST OF NORTHEASTERN ND WEST OF THE VALLEY AS
WINDS IN DVL ARE GUSTING TO AROUND 32 KTS AND HAVE SEEN VSBYS GO
DOWN TO 3 MILES.
UPDATE ISSUED AT 648 PM CST MON DEC 16 2013
CHANGE OVER TO VCP 31 HELPING DETECT SOME SNOW SHOWERS MOVING
THROUGH THE NORTHEASTERN ND TO THE SOUTHEAST. SHOULD ARRIVE AT
GRAND FORKS OVER NEXT COUPLE OF HOURS AND PROCEED ON DOWN TO THE
DETROIT LAKES AREA AFTER MID EVENING. SOME WEAKER RETURNS OVER
NORTHERN VALLEY APPEAR TO BE MID LEVEL CLOUDS PER HALLOCK METAR.
DID INCREASE POPS HIGH CHANCE / SCATTERED COVERAGE THROUGH MID
EVENING THEN LIKELIES FOR THE LATE EVENING...EXPECTING THEM TO
INTENSIFY A BIT AS THEY ENTER WESTERN MN. DO EXPECT SHOWERS TO BE
THROUGH AREA BY 06Z BUT WILL KEEP INHERITED POPS AFTER MIDNIGHT
UNTIL NEW NAM DATA COMES IN. LAPS HAS A DECENT HANDLE ON TEMP
TRENDS...INCREASING FROM WEST TO EAST AS WESTERLY FLOW
CONTINUES...AND HAVE ADJUSTED HOURLIES THROUGH MIDNIGHT PER THE
LAPS. TEMPS STILL EXPECTED TO BE QUITE A BIT CHILLIER OVER THE
EAST VS THE BALMY WEST.
&&
.SHORT TERM...(THIS EVENING THROUGH TUESDAY NIGHT)
ISSUED AT 331 PM CST MON DEC 16 2013
AS EXPECTED WEST WINDS HAVE ARRIVED WITH TEMPS NR 30 IN ERN ND AND
THE RRV WITH WARMER AIR LAST TO ARRIVE IN NORTHERN MN. UPPER LOW
OVER NORTHWESTERN ONTARIO WILL TAP INTO SOME COLDER AIR IN
NORTHEASTERN MANITOBA TONIGHT AND BRING SOUTH SOME COLDER 850 MB
AIR INTO NW MN/FAR NE ND AFTER MIDNIGHT. SO WHILE THIS EVENING
WILL REMAIN MILD EXPECT A DECENT COOL DOWN AFTER 06Z. A SHORT WAVE
FROM SOUTHWESTERN SASK INTO SOUTH DAKOTA WILL BRING SOME - SN TO
ERN MT/SW ND INTO PARTS OF NRN SD/SRN MN TONIGHT. MORE SPOTTY LIGHT
SNOWS REST OF THE AREA AS A WEAKER SHORT WAVE MOVES SOUTHEAST
ACROSS SOUTHEAST SASK INTO THE RED RIVER VALLEY.
TUESDAY WILL SEE HIGH PRESSURE RIDGE BUILD IN AND SHOULD SEE A
FAIR AMOUNT OF SUN WITH HIGHS QUITE A BIT COLDER IN THE TEENS OR
LOWER 20S. COLD TUESDAY NIGHT IN NW MN WITH LOWS A BIT BELOW
ZERO....BUT CLOUDS MOVING IN IN WARM ADV WILL MEAN NOT AS COLD IN
ERN ND.
.LONG TERM...(WEDNESDAY THROUGH MONDAY)
ISSUED AT 331 PM CST MON DEC 16 2013
WEDNESDAY WILL SEE LOW PRESSURE MOVE NORTH OF THE BORDER. SOME
WARM ADV -SN MAY IMPACT LAKE OF THE WOODS....BUT MOSTLY NORTH OF
THE BORDER. OTHERWISE 850 MB TEMPS ACTUALLY WARMER WED THAN TODAY
WITH TEMPS IN THE ZERO NORTH TO +4C RANGE BUT WINDS LIGHTER AND
MORE SOUTHERLY AND THUS NOT QUITE THE WARM WIND. BUT STILL EXPECT
20S FOR MANY AREAS.
COLDER AIR WILL BEGIN TO DROP SOUTH BEHIND THE CANADIAN LOW LATE
WED NIGHT AND THEN PUSH SOUTH QUICKLY THURSDAY. NEXT SYSTEM WILL
MOVE EAST THRU SOUTH DAKOTA INTO SOUTHERN MN THURSDAY AFTN
SPREADING SOME SNOW ALONG THE SD/ND BORDER.
FOR THU NIGHT THE MODELS REMAIN IN GOOD AGREEMENT IN DEPICTING A
SHIFT WAVE SHIFTING INTO MN. WILL LINGER LIGHT SNOW CHANCES MAINLY
ALONG AND SOUTH OF THE HIGHWAY 2 CORRIDOR. 500MB FLOW THEN SHIFTS
BACK TO THE NORTHWEST WITH SFC HIGH PRESSURE FOR FRI. STILL NOT
LOOKING LIKE MUCH WEATHER WISE FRI NIGHT INTO SAT WITH MOST LIGHT
SNOW STAYING NORTH OF THE CANADIAN BORDER. BY SAT NIGHT INTO SUN
HIGH PRESSURE MOVES BACK IN WITH SOME CHILLY AIR ONCE AGAIN. LARGER
MODEL DIFFERENCES COME INTO PLAY BY MONDAY SO CONFIDENCE DROPS
CONSIDERABLY. GUIDANCE TEMPS SHOWING MONDAY HIGHS QUITE A BIT COOLER
THAN THE PRIOR MODEL RUN. WITH THE LOW CONFIDENCE WILL RUN WITH THE
GUIDANCE OUTPUT FOR MONDAY AND SEE WHAT LATER RUNS HAVE IN STORE.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z TUESDAY NIGHT)
ISSUED AT 1148 PM CST MON DEC 16 2013
TVF SHOULD SCT OUT OVER NEXT HOUR AND BJI BY AROUND 09Z BEFORE VFR
DECK SINKS INTO NW MN AROUND 10Z. CIGS HAVE BEEN IN THE 3K TO 5K
RANGE WITH LIGHT SNOW...HOWEVER THINK THEY WILL CONTINUE TO SINK
AND BE MVFR BEFORE REACHING BJI EARLY TUE AM. WILL KEEP TVF VFR
BUT GO MVFR FOR AM HOURS AT BJI. SHOULD SEE GRADUAL CLEARING FROM
WEST TO EAST TOMORROW...WITH MORE VFR CIGS MOVING IN AFT 03Z WED.
&&
.FGF WATCHES/WARNINGS/ADVISORIES...
ND...NONE.
MN...NONE.
&&
$$
UPDATE...SPEICHER
SHORT TERM...RIDDLE
LONG TERM...GODON/RIDDLE
AVIATION...SPEICHER
AREA FORECAST DISCUSSION
NWS PORTLAND OR
740 PM PST WED DEC 18 2013
.SYNOPSIS..RAIN AND SNOW SHOWERS WILL DIMINISH THROUGH THE EVENING.
CLEARING SKIS WILL DEVELOP FROM NORTH TO SOUTH TONIGHT...LEADING TO
COLDER OVERNIGHT LOWS AND THE POTENTIAL FOR ICY ROAD SURFACES FOR
TOMORROW MORNING. THERE WILL BE A BREAK IN PRECIPITATION TOMORROW
BEFORE A WARMER SYSTEM BRINGS RAIN AND MOUNTAIN SNOW ON FRI. IT
CONTINUES TO LOOK LIKE NORTHERN VALLEY LOCATIONS MAY SEE PRECIP
START AS SNOW FRI MORNING. TEMPS WILL WARM SIGNIFICANTLY LATER
FRI...WITH MODERATE TO HEAVY RAIN EXPECTED OVER MOST OF THE AREA. AN
UPPER LEVEL RIDGE WILL SET UP OVER THE NE PAC LATE IN THE
WEEK...WITH SEVERAL SYSTEMS PUSHING OVER THE TOP OF THE RIDGE
THROUGH EARLY NEXT WEEK.
&&
.UPDATE...HOPEFULLY YOU ARE ALL NOT CONFUSED BY NOW BY OUR
TECHNOLOGICAL CHALLENGES...BUT THE LATEST SPECIAL WEATHER STATEMENT
FOR SLICK ROADS IS FOR TOMORROW MORNINGS COMMUTE...THURSDAY MORNING
AND NOT FRIDAY MORNING.
LATEST GRIDS ARE BEING SENT TO REFLECT LESS IN THE WAY OF FOG
TONIGHT. COLD AIR ADVECTION AND MOISTURE PROFILES DECREASING WITH
HEIGHT IN THE LOWEST LEVELS COUPLES WITH CLEARING SKIES TO SUGGEST
TEMPERATURES IN MOST PLACES WILL BE CHASING DEWPOINTS TONIGHT AND
LIMIT FOG POTENTIAL. OTHERWISE...WET ROADS AND MOST PLACES DIPPING
TO NEAR FREEZING (URBAN AREAS) OR BELOW MEANS THAT THERE WILL LIKELY
BE SOME SLICK OR ICY SPOTS ON ROADWAYS LATE TONIGHT INTO EARLY
FRIDAY.
THERE ARE SOME SHOWERS OUT THERE MOSTLY IN THE FORM OF RAIN...BUT
EXPECT TO SEE SOME SNOWFLAKES MIXED IN AT TIMES EVEN AT THE LOWEST
ELEVATIONS...AS HAS BEEN REPORTED IN ALBANY THIS EVENING. THERE ARE
SOME CONVERGENCE ZONE SHOWERS NORTH OF THE AREA THAT ARE PUSHING
THROUGH LEWIS COUNTY WASHINGTON. LATEST HRRR SUGGESTS THESE DIE OUT
BEFORE GETTING INTO OUR AREA...THOUGH POSSIBLY SOME FLAKES AS WELL
FOR COWLITZ COUNTY.
/KMD
.SHORT TERM...TONIGHT THROUGH SATURDAY... A COLD UPPER LEVEL TROUGH
IS BRINGING INCREASING SHOWERS AND LOWERING SNOW LEVELS ACROSS THE
REGION THIS AFTERNOON. THE BEST SHOWERS ACTIVITY IS CURRENTLY BEING
OBSERVED OVER THE S WA/N OR COAST AND COAST RANGE AND WILLAPA HILLS.
AS THE TROUGH CONTINUES TO PUSH SOUTH THE FOCUS OF THE SHOWER
ACTIVITY WILL BECOME FOCUSED OVER THE N WILLAMETTE VALLEY AND
CENTRAL OR COAST DURING THE LATE AFTERNOON...THEN OVER THE
CENTRAL/SOUTHERN VALLEY THIS EVENING. AS THE COLD AIR MOVES IN
ALOFT...SNOW LEVELS SHOULD FALL DOWN INTO THE COAST RANGE AND
CASCADE FOOTHILLS...BUT ONLY LIGHT ACCUMULATIONS ARE EXPECTED. THE
POTENTIAL FOR ANY SNOW REACHING DOWN TO VALLEY FLOOR LOCATIONS LOOKS
TO BE LOW. BY THE TIME IT IS COLD ENOUGH...IT APPEARS THAT SHOWER
ACTIVITY WILL BE BASICALLY OVER. BUT IF WE DO MANAGE TO SEE ANY
SHOWERS LATER THIS EVENING...A FEW SPOTS MIGHT SEE SNOW MIXING IN
WITH THE RAIN.
THE FCST MODELS ARE INDICATING RAPID CLEARING TONIGHT FROM NORTH TO
SOUTH AS COLD AIR STREAMS IN BEHIND THE UPPER LEVEL TROUGH AXIS.
BASED ON THE CLEARING APPARENT ON VISIBLE SATELLITE OVER THE OLYMPIC
PENINSULA AND ADJACENT COASTAL WATERS...THE MODELS ARE LIKELY CORRECT
ABOUT THIS. THUS THE CURRENT FCST STARTS TO CLEAR THINGS IN THE
NORTHERN TIER OF THE FCST AREA LATE THIS EVENING...THEN CLEARING OUT
DOWN SOUTH OVERNIGHT INTO EARLY TOMORROW MORNING. THIS SHOULD ALLOW
TEMPS TO FALL SIGNIFICANTLY OVERNIGHT...LEADING TO SOME CONCERN THAT
ANY MOISTURE ON ROAD SURFACE TONIGHT MAY FREEZE AND CREATE SOME
SLIPPERY CONDITIONS FOR TOMORROW MORNING/S COMMUTE. THERE IS ALSO A
HIGH LIKELIHOOD THAT AREAS OF FOG WILL FORM EARLY TOMORROW MORNING AS
UPPER LEVEL RIDGING BEGINS TO BUILD IN ALOFT.
TOMORROW SHOULD PROVIDE A RELATIVELY QUIET DAY AS THE SHORTWAVE UPPER
LEVEL RIDGING IS OVER THE REGION. ANY LOW LEVEL CLOUDS OR FOG SHOULD
DISSIPATE DURING THE DAY...PROVIDING SOME SUN BREAKS FOR MOST. HIGH
CLOUDS MAY BEGIN TO STREAM IN ALOFT LATE TOMORROW AHEAD OF THE NEXT
SYSTEM THAT IS SLATED TO IMPACT US ON FRI.
THE MODEL SOLUTIONS FOR THE FRI SYSTEM CONTINUE TO RAISE CONCERNS OF
A WINTRY MIX AT SOME LOW ELEVATION SITES TO START THE EVENT. THE 12Z
UW WRF-GFS IS INDICATING THAT SOME LIGHT SNOW ACCUMULATIONS ARE
POSSIBLE BEFORE DAY BREAK FRI FOR THE LOWER COLUMBIA BASIN AND I-5
CORRIDOR IN S WA. IT ALSO INDICATES THE POTENTIAL FOR SOME LIGHT SNOW
FALLING INTO THE PORTLAND METRO AREA AROUND THE FRI MORNING COMMUTE.
THE SYSTEM IS FCST TO BRING SOME FAIRLY STRONG SW WINDS AT THE LOW
LEVELS TO SCOUR OUT THE COLD AIR...AND THE COLD POOL LEADING OVER THE
REGION LEADING INTO THE EVENT IS NOT EXPECTED TO BE VERY DEEP. SO THE
CHANCES FOR A HIGH IMPACT EVENT DO NOT APPEAR TO BE VERY GOOD.
HEAVIER RAIN WILL SPREAD OVER THE REGION LATER WED MORNING AND
AFTERNOON...WITH SNOW LEVELS RISING RAPIDLY INTO THE HIGHER CASCADE
TERRAIN. IT APPEARS THAT MOST LOCATIONS WILL GET A SHOT OF MODERATE
RAIN BY FRI NIGHT. PRECIP IS MODELED TO TAPER OFF FRI NIGHT INTO
EARLY SAT...LEAVING JUST A MILDER AND CLOUDY DAY ON SAT IN ONSHORE
FLOW. PYLE
.LONG TERM...SATURDAY NIGHT THROUGH TUESDAY...UPPER LEVEL RIDGING
OVER THE EPAC WILL DOMINATE MUCH OF THE EXTENDED FORECAST. THIS WILL
CONTINUE THE NORTHWESTERLY UPPER LEVEL FLOW THROUGH THE PERIOD...AND
PREVENT ANY SUBSTANTIAL SYSTEMS FROM AFFECTING THE AREA. WARM FRONT
ON SUNDAY FOLLOWED BY A DECAYING COLD FRONT ON MONDAY WILL BRING
MOISTURE INTO THE PAC NW FROM TIME TO TIME...HOWEVER THE PRECIP WILL
GENERALLY REMAIN CONFINED TO THE MORE NORTHERN AREAS OF THE CWA. BY
LATE MONDAY THE MODELS DIVERGE...WITH THE ECMWF ALLOWING COLD NORTH OR
NORTHEASTERLY UPPER FLOW TO DEVELOP AS AN UPPER TROUGH DIVES SOUTH
INTO THE GREAT BASIN FROM CANADA. HOWEVER...THE GFS PHASES THAT LOW
WITH A LONGWAVE TROUGH OVER THE MID-WEST...WHICH WOULD LEAVE THE
PACNW UNDER CONTINUED HIGH PRESSURE ALOFT. BURGESS
&&
.AVIATION...CHANGE IN AIR MASSES UNDERWAY THIS EVENING...FROM
COOL MOIST TO COOL DRY. WIDESPREAD IFR STRATUS AND PATCHY FOG
INLAND...BUT CONDITIONS ALONG THE COAST HAVE IMPROVED TO MOSTLY
VFR. AS A FRONT NOW NEAR KAST MOVES S AND E THIS AFTERNOON AND
EVENING...CONDITIONS WILL IMPROVE TO MVFR...AND EVENTUALLY VFR
TOWARDS 00Z TO 02Z. HIGHER TERRAIN REMAINS OBSCURED IN CLOUDS
THROUGH 04Z...BUT LIKELY LONGER AGAINST THE CASCADES AND POINTS TO
E AND S OF KEUG. AIR MASS WILL DRY TONIGHT...BUT STILL EXPECT
WITH POCKETS OF FOG/LOW STRATUS REFORMING IN VALLEYS/BAYS AFTER
10Z...MAINLY N OF A KONP TO KSLE LINE.
KPDX AND APPROACHES...IFR STRATUS CONTINUES...BUT IS STARTING TO
BREAK UP A BIT. CLOUDS WILL LIFT TO MVFR THIS AFTERNOON...WITH VFR
CIGS EXPECTED BY 00Z TO 02Z. SHOULD REMAIN VFR THROUGH 08Z...THEN
AREAS OF IFR STRATUS AND FOG REFORMING. ROCKEY
&&
.MARINE...AT 2 PM...COLD FRONT WAS OVER THE S WASHINGTON COASTAL
WATERS...AND MOVING TO THE S. N TO NW WINDS WILL INCREASE BEHIND
THE FRONT...WITH GUSTS TO 25 KT.
SEAS CURRENTLY 6 TO 7 FT...BUT WILL BUILD LATE TODAY AND EVENING
AS WINDS INCREASE. STILL EXPECTING SEAS OF 9 TO 11 FT LATER
TODAY AND TONIGHT WITH HIGHEST OVER THE OUTER WATERS.
SEAS AND WINDS EASE BACK ON THU AND THU NIGHT. BUT ANOTHER FRONT
WILL BRING GUSTY WINDS...POSSIBLY GALE FORCE...AND HIGHER SEAS
FOR FRI AND SAT. ROCKEY.
&&
.PQR WATCHES/WARNINGS/ADVISORIES...
OR...NONE.
WA...NONE.
PZ...SMALL CRAFT ADVISORY FOR WINDS AND HAZARDOUS SEAS NOW
THROUGH THU AM ON ALL COASTAL WATERS.
SMALL CRAFT ADVISORY FOR ROUGH COLUMBIA BAR CONDITIONS
THROUGH EARLY THIS EVENING.
&&
$$
MORE WEATHER INFORMATION ONLINE AT..
HTTP://WEATHER.GOV/PORTLAND
INTERACT WITH US VIA SOCIAL MEDIA
WWW.FACEBOOK.COM/US.NATIONALWEATHERSERVICE.PORTLAND.GOV
WWW.TWITTER.COM/NWSPORTLAND
THIS DISCUSSION IS FOR NORTHWEST OREGON AND SOUTHWEST WASHINGTON FROM
THE CASCADE CREST TO 60 NAUTICAL MILES OFFSHORE. THE AREA IS COMMONLY
REFERRED TO AS THE FORECAST AREA.
AREA FORECAST DISCUSSION
NWS BLACKSBURG VA
1106 AM EST TUE DEC 17 2013
.SYNOPSIS...
LOW PRESSURE WAS OVER LAKE ERIE WITH A COLD FRONT TRAILING INTO
MISSOURI. THIS LOW WILL MOVE EAST TODAY PUSHING THE COLD FRONT
THROUGH THE REGION. WEDNESDAY AND THURSDAY HIGH PRESSURE WILL BE
OVER THE AREA.
&&
.NEAR TERM /UNTIL 7 PM THIS EVENING/...
AS OF 1052 AM EST TUESDAY...
STOUT UPPER WAVE/CLIPPER AS USUAL LOOKING TO OUTPERFORM MODEL RUNS
FROM THE PAST FEW DAYS. ENOUGH QPF AND COLD AIR WITH THIS SYSTEM
TO PRODUCE ADVISORY CRITERIA SNOW ACROSS THE HIGHEST TERRITORY OF
GREENBRIER AND SUMMERS THIS AFTERNOON AND EARLY EVENING.
NAM/GFS/SREF HAVE 6HR QPF PRETTY CLOSE TO 0.3" WHEN AIR IS COLD
ENOUGH FOR SNOW ABOVE 2500 FEET FROM 18Z/1P-0Z/7P. POTENTIAL FOR
A BURST OF SNOW THAT PUTS DOWN A QUICK HALF INCH THIS AFTERNOON
COULD COMPLICATE RUSH HOUR TRAVEL/SCHOOLS LETTING OUT. WOULD NOT
BE SURPRISED BY A 2-4" SNOWFALL BY THIS EVENING ACROSS THE
WESTERN SLOPES ABOVE 2500 FEET SUMMERS/GREENBRIER. NOT OUT OF THE
QUESTION THAT EVEN SOME OF THE CITIES AT LOWER ELEVATIONS PICK UP
A QUICK COATING/HALF INCH WHEN THE CHANGEOVER OCCURS THIS
AFTERNOON. HOWEVER...SLOWER CHANGEOVER AND WET GROUND MAY MITIGATE
ACCUMS GREATLY AT THE LOWER ELEVATIONS.
BACK EAST THROUGH THE NEW RIVER VALLEY/SOUTHSIDE/PIEDMONT....WINDS
MAY GUST TO 25 KTS AS CLOUDS BEGIN TO COVER MOST OF THE CWA...BUT
AROUND 35 KTS NW NC NEAR SUNSET. DOWNSLOPE WARMING THIS PM MAY BE
STUNTED BY THE OVERCAST. SINCE THIS DOWNSLOPE FLOW IS MORE OF THE
WESTERLY VARIETY AS OPPOSED TO NW-NNW...POSSIBLE THAT SOME OF THE
PRECIP FROM THIS SYSTEM SNEAKS THROUGH SE WEST VA AND MAYBE ENTERS
THE NEW RIVER VALLEY LATE THIS AFTERNOON OR EVENING...POSSIBLY AS
SNOW SHOWERS. WILL BE TAKING A FURTHER LOOK AT THIS FOR THE
AFTERNOON PACKAGE.
&&
.SHORT TERM /7 PM THIS EVENING THROUGH FRIDAY NIGHT/...
AS OF 300 AM EST TUESDAY...
COLD ADVECTION SETS IN BEHIND THE FRONT. THE BEST PRESSURE RISES
WILL BE TONIGHT...PEAKING AROUND 06Z. WINDS WILL BE CLOSE TO
ADVISORY CRITERIA OF 40 KNOT GUSTS FROM GRAYSON COUNTY SOUTH TO
WATAUGA COUNT
DURING THE DAY WEDNESDAY...THE PRESSURE GRADIENT WEAKENS AS SURFACE
HIGH PRESSURE BUILD OVER THE REGION AND THE UPPER LEVEL SHORTWAVE
TROUGH MOVES INTO THE WESTERN ATLANTIC. THE IMPACT ON OUR REGION
WILL BE A GRADUAL DECREASE TO BOTH THE WIND SPEED ACROSS THE
REGION...AND THE UPSLOPE SNOW SHOWERS ACROSS WESTERN GREENBRIER
COUNTY WV.
WEDNESDAY NIGHT INTO THURSDAY...WILL BEGIN A PERIOD OF MILDER
CONDITIONS ACROSS THE AREA AS THE CENTER OF THE SURFACE HIGH SHIFTS
TO THE COAST AND THERE IS A DEVELOPMENT OF A TROUGH ACROSS THE
CENTRAL PORTION OF THE COUNTRY. THE RESULT WILL BE AN INCREASING
SOUTHWESTERLY FLOW AND WARM AIR ADVECTION ACROSS THE REGION.
THIS PATTERN WILL CONTINUE INTO FRIDAY AS THE UPPER TROUGH CONTINUES
TO STRENGTHEN. ALSO...A DECENT FETCH OF MOISTURE WILL DEVELOP FROM
OFF THE GULF OF MEXICO ALONG THE EAST SIDE OF THE TROUGH THAT WILL
EXTEND FROM THE LOWER MISSISSIPPI VALLEY NORTHEAST INTO THE OHIO
VALLEY. THIS MOISTURE WILL GRADUALLY PROGRESS EASTWARD AS THE TROUGH
EJECTS EASTWARD BY LATE FRIDAY NIGHT. THE RESULT FOR OUR REGION WILL
BE A CONTINUED TREND OF MILDER TEMPERATURES AND INCREASING CHANCES
OF PRECIPITATION...ESPECIALLY IN THE WEST...LATE FRIDAY INTO FRIDAY
NIGHT.
&&
.LONG TERM /SATURDAY THROUGH MONDAY/...
AS OF 253 PM EST MONDAY...
A MILD WEEKEND EXPECTED WITH A COOL DOWN FOR EARLY NEXT WEEK. A COLD
FRONT WITH SEVERAL WAVES OF LOW PRESSURE ALONG IT WILL TRAVEL EAST
AND ADVANCE THROUGH OUR REGION BY SUNDAY NIGHT. SOUTHWEST FLOW AND
INCREASING HEIGHTS WILL RESULT IN WARMER THAN NORMAL TEMPERATURES ON
FRIDAY. AS THE FRONT APPROACHES FROM THE OHIO VALLEY FRIDAY WILL
ALLOW FOR LIGHT POPS IN THE MOUNTAINS ON FRIDAY.
A WAVE OF LOW PRESSURE RIDING NORTH ALONG THE BOUNDARY WILL PUSH
THE COLD FRONT CLOSER TO US ON SATURDAY. POPS INCREASE FOR THE
ENTIRE FORECAST AREA ON SATURDAY AS THE FRONT EDGES CLOSER.
UNSEASONABLY WARM TEMPERATURES EXPECTED FOR SATURDAY WITH HIGHS
FROM MID 50S IN THE MOUNTAINS TO NEAR 70 DEGREES IN SOUTHEAST. IN
GENERAL...KEPT SCATTERED POPS FOR SATURDAY AND SATURDAY NIGHT. THE
WAVE THAT LIFTS NORTH ALONG THE BOUNDARY SATURDAY NIGHT MAY SLOW
ITS ADVANCE EAST SATURDAY NIGHT INTO SUNDAY. PLAYED LOWS SATURDAY
NIGHT WITH READINGS FROM THE UPPER 40S IN THE WEST TO MID 50S IN
THE EAST. LEANED TOWARDS THE SLOWER TIMING OF THE COLD FRONT ON
SUNDAY COMPARED TO GFS.
HIGHS ON SUNDAY WILL RANGE FROM AROUND 60 DEGREES IN THE WEST TO
APPROACHING 70 DEGREES IN THE EAST. LOW TEMPERATURES SUNDAY NIGHT
WILL BE DEPENDING ON TIMING OF LOW PRESSURE AND ITS MOVEMENT.
LEANED TOWARDS ECMWF ENSEMBLE WITH VALUES FROM THE MID 30S IN THE
NORTHWEST TO AROUND 50 DEGREES IN THE SOUTHEAST. MORE SEASONABLE
WEATHER RETURNS ON MONDAY WITH A CHANCE OF SHOWERS AND HIGHS IN
THE LOWER 40S IN THE MOUNTAINS TO THE MID 50S IN THE PIEDMONT.
&&
.AVIATION /16Z TUESDAY THROUGH SATURDAY/...
AS OF 700 AM EST TUESDAY...
SHORT WAVE CROSSING THE OHIO VALLEY AND ASSOCIATED WARM AIR
ADVECTION WAS PRODUCING LIGHT PRECIPITATION IN WEST VIRGINIA THIS
MORNING. ICING IS POSSIBLE AROUND LEWISBURG WHERE THE TEMPERATURE
WAS STILL BELOW FREEZING. OTHERWISE THIS MORNING EXPECT MID AND
HIGH CLOUDS EAST OF THE BLUE RIDGE.
A STRONGER SHORT WAVE CROSSES THROUGH THE AREA THIS AFTERNOON AND
EVENING. LOCAL WRF AND THE LAST FEW RUNS OF THE RAP MODELS
INDICATED THE HIGHEST PROBABILITY OF PRECIPITATION WILL BE IN THE
MOUNTAINS AND ON THE WESTERN SLOPES WHERE GOOD SYNOPTIC SCALE LIFT
WILL COMBINE WITH UPSLOPE FLOW TO PRODUCE PRECIPITATION. HIGH
CONFIDENCE OF SNOW AND MVFR CEILINGS AND VISIBILITIES NEAR KBLF
AND KLWB AROUND 00Z TONIGHT. MUCH LOWER CONFIDENCE ABOUT THE
CHANCE OF SHOWERS IN CENTRAL VIRGINIA AND NORTH CAROLINA LATE THIS
AFTERNOON ALONG A COLD FRONT THAT WILL BE MOVING THROUGH THE
REGION.
BEHIND THE FRONT TONIGHT WINDS WILL BE STRONG AND GUSTY. WIND
GUSTS OF 25 TO 25 KNOTS WILL BE COMMON IN THE MOUNTAINS...
ESPECIALLY ALONG THE RIDGES. MVFR CLOUDS WILL PERSIST AT KLWB AND
KBLF. WINDS WILL BEGIN TO DIMINISH WEDNESDAY MORNING AS HIGH
PRESSURE BUILDS INTO THE AREA.
HIGH PRESSURE AND VFR CONDITIONS WILL CONTINUE INTO THURSDAY.
THE WEATHER WILL BE DETERIORATING FOR THE WEEKEND AS NEXT LOW
PRESSURE SYSTEM MOVES IN FROM THE WEST WITH PRECIPITATION AND MVFR
OR LOWER CONDITIONS EXPECTED. A COLD FRONT WITH SEVERAL WAVES OF
LOW PRESSURE ALONG IT WILL TRAVEL EAST AND ADVANCE THROUGH OUR
REGION BY SUNDAY NIGHT.
&&
.RNK WATCHES/WARNINGS/ADVISORIES...
VA...NONE.
NC...NONE.
WV...NONE.
&&
$$
SYNOPSIS...AMS
NEAR TERM...KM
SHORT TERM...AMS/DS
LONG TERM...KK
AVIATION...AMS
AREA FORECAST DISCUSSION
NWS BLACKSBURG VA
711 AM EST TUE DEC 17 2013
.SYNOPSIS...
LOW PRESSURE WAS OVER LAKE ERIE WITH A COLD FRONT TRAILING INTO
MISSOURI. THIS LOW WILL MOVE EAST TODAY PUSHING THE COLD FRONT
THROUGH THE REGION. WEDNESDAY AND THURSDAY HIGH PRESSURE WILL BE
OVER THE AREA.
&&
.NEAR TERM /THROUGH TONIGHT/...
AS OF 700 AM EST TUESDAY...
WARM ADVECTION HAD BROUGHT TEMPERATURES UP SINCE MIDNIGHT. SOME LIGHT
PRECIPITATION TO THE WEST OF THE COUNTY WARNING AREA WAS DEVELOPING
JUST WEST OF THE FORECAST AREA. CLOUDS HAVE LOWERED AT HOT SPRINGS
AND LEWISBURG SO MORE CONFIDENCE NOW THAT PRECIPITATION IN THE FAR
NORTHWEST CORNER OF THE FORECAST AREA MAY BE REACHING THE GROUND.
A SURFACE LOW PRESSURE SYSTEM OVER OHIO EARLY THIS MORNING WILL MOVE
EAST...PULLING A WARM FRONT NORTH THROUGH THE MID ATLANTIC STATES
THIS MORNING AND BRINGING A COLD FRONT INTO THE MOUNTAINS THIS
AFTERNOON. HAVE ADDED A LOW PROBABILITY OF SHOWERS EAST OF
DANVILLE AND LYNCHBURG THIS EVENING. LAPSE RATES AND FORCING WILL
BE GOOD BUT WILL HAVE TO OVERCOME DOWNSLOPE WINDS.
COLD ADVECTION SETS IN BEHIND THE FRONT. THE BEST PRESSURE RISES
WILL BE TONIGHT...PEAKING AROUND 06Z. WINDS WILL BE CLOSE TO
ADVISORY CRITERIA OF 40 KNOT GUSTS FROM GRAYSON COUNTY SOUTH TO
WATAUGA COUNTY SO WIND ADVISORY MAY BE ISSUED LATER THIS MORNING.
A STRONG SHORT WAVE OVER THE UPPER MISSISSIPPI VALLEY WILL TRACK
TOWARD THE MID ATLANTIC REGION TODAY AND CROSS THE FORECAST AREA
THIS EVENING. BY THEN THE COLD FRONT WILL BE THROUGH AND
TEMPERATURES WILL BE COLD ENOUGH FOR SNOW. EXPANDING PROBABILITY OF
PRECIPITATION INTO THE NORTHWEST NORTH CAROLINA MOUNTAINS BY LATE
AFTERNOON...FOLLOWING THE TRACK OF THE SHORT WAVE ON THE SREF AND
LATEST LOCAL WRF MODELS. THERMAL PROFILE FROM THE NAM BUFKIT AT
BLUEFIELD AND LEWISBURG START OUT AS RAIN IN THE LATE AFTERNOON THEN
CHANGE TO SNOW BY 00Z. LOCAL WRF WAS SLIGHTLY COLDER...SHOWING THE
EVENT BEGINNING AS SNOW.
&&
.SHORT TERM /WEDNESDAY THROUGH FRIDAY NIGHT/...
AS OF 300 AM EST TUESDAY...
DURING THE DAY WEDNESDAY...THE PRESSURE GRADIENT WEAKENS AS SURFACE
HIGH PRESSURE BUILD OVER THE REGION AND THE UPPER LEVEL SHORTWAVE
TROUGH MOVES INTO THE WESTERN ATLANTIC. THE IMPACT ON OUR REGION
WILL BE A GRADUAL DECREASE TO BOTH THE WIND SPEED ACROSS THE
REGION...AND THE UPSLOPE SNOW SHOWERS ACROSS WESTERN GREENBRIER
COUNTY WV.
WEDNESDAY NIGHT INTO THURSDAY...WILL BEGIN A PERIOD OF MILDER
CONDITIONS ACROSS THE AREA AS THE CENTER OF THE SURFACE HIGH SHIFTS
TO THE COAST AND THERE IS A DEVELOPMENT OF A TROUGH ACROSS THE
CENTRAL PORTION OF THE COUNTRY. THE RESULT WILL BE AN INCREASING
SOUTHWESTERLY FLOW AND WARM AIR ADVECTION ACROSS THE REGION.
THIS PATTERN WILL CONTINUE INTO FRIDAY AS THE UPPER TROUGH CONTINUES
TO STRENGTHEN. ALSO...A DECENT FETCH OF MOISTURE WILL DEVELOP FROM
OFF THE GULF OF MEXICO ALONG THE EAST SIDE OF THE TROUGH THAT WILL
EXTEND FROM THE LOWER MISSISSIPPI VALLEY NORTHEAST INTO THE OHIO
VALLEY. THIS MOISTURE WILL GRADUALLY PROGRESS EASTWARD AS THE TROUGH
EJECTS EASTWARD BY LATE FRIDAY NIGHT. THE RESULT FOR OUR REGION WILL
BE A CONTINUED TREND OF MILDER TEMPERATURES AND INCREASING CHANCES
OF PRECIPITATION...ESPECIALLY IN THE WEST...LATE FRIDAY INTO FRIDAY
NIGHT.
&&
.LONG TERM /SATURDAY THROUGH MONDAY/...
AS OF 253 PM EST MONDAY...
A MILD WEEKEND EXPECTED WITH A COOL DOWN FOR EARLY NEXT WEEK. A COLD
FRONT WITH SEVERAL WAVES OF LOW PRESSURE ALONG IT WILL TRAVEL EAST
AND ADVANCE THROUGH OUR REGION BY SUNDAY NIGHT. SOUTHWEST FLOW AND
INCREASING HEIGHTS WILL RESULT IN WARMER THAN NORMAL TEMPERATURES ON
FRIDAY. AS THE FRONT APPROACHES FROM THE OHIO VALLEY FRIDAY WILL
ALLOW FOR LIGHT POPS IN THE MOUNTAINS ON FRIDAY.
A WAVE OF LOW PRESSURE RIDING NORTH ALONG THE BOUNDARY WILL PUSH
THE COLD FRONT CLOSER TO US ON SATURDAY. POPS INCREASE FOR THE
ENTIRE FORECAST AREA ON SATURDAY AS THE FRONT EDGES CLOSER.
UNSEASONABLY WARM TEMPERATURES EXPECTED FOR SATURDAY WITH HIGHS
FROM MID 50S IN THE MOUNTAINS TO NEAR 70 DEGREES IN SOUTHEAST. IN
GENERAL...KEPT SCATTERED POPS FOR SATURDAY AND SATURDAY NIGHT. THE
WAVE THAT LIFTS NORTH ALONG THE BOUNDARY SATURDAY NIGHT MAY SLOW
ITS ADVANCE EAST SATURDAY NIGHT INTO SUNDAY. PLAYED LOWS SATURDAY
NIGHT WITH READINGS FROM THE UPPER 40S IN THE WEST TO MID 50S IN
THE EAST. LEANED TOWARDS THE SLOWER TIMING OF THE COLD FRONT ON
SUNDAY COMPARED TO GFS.
HIGHS ON SUNDAY WILL RANGE FROM AROUND 60 DEGREES IN THE WEST TO
APPROACHING 70 DEGREES IN THE EAST. LOW TEMPERATURES SUNDAY NIGHT
WILL BE DEPENDING ON TIMING OF LOW PRESSURE AND ITS MOVEMENT.
LEANED TOWARDS ECMWF ENSEMBLE WITH VALUES FROM THE MID 30S IN THE
NORTHWEST TO AROUND 50 DEGREES IN THE SOUTHEAST. MORE SEASONABLE
WEATHER RETURNS ON MONDAY WITH A CHANCE OF SHOWERS AND HIGHS IN
THE LOWER 40S IN THE MOUNTAINS TO THE MID 50S IN THE PIEDMONT.
&&
.AVIATION /12Z TUESDAY THROUGH SATURDAY/...
AS OF 700 AM EST TUESDAY...
SHORT WAVE CROSSING THE OHIO VALLEY AND ASSOCIATED WARM AIR
ADVECTION WAS PRODUCING LIGHT PRECIPITATION IN WEST VIRGINIA THIS
MORNING. ICING IS POSSIBLE AROUND LEWISBURG WHERE THE TEMPERATURE
WAS STILL BELOW FREEZING. OTHERWISE THIS MORNING EXPECT MID AND
HIGH CLOUDS EAST OF THE BLUE RIDGE.
A STRONGER SHORT WAVE CROSSES THROUGH THE AREA THIS AFTERNOON AND
EVENING. LOCAL WRF AND THE LAST FEW RUNS OF THE RAP MODELS
INDICATED THE HIGHEST PROBABILITY OF PRECIPITATION WILL BE IN THE
MOUNTAINS AND ON THE WESTERN SLOPES WHERE GOOD SYNOPTIC SCALE LIFT
WILL COMBINE WITH UPSLOPE FLOW TO PRODUCE PRECIPITATION. HIGH
CONFIDENCE OF SNOW AND MVFR CEILINGS AND VISIBILITIES NEAR KBLF
AND KLWB AROUND 00Z TONIGHT. MUCH LOWER CONFIDENCE ABOUT THE
CHANCE OF SHOWERS IN CENTRAL VIRGINIA AND NORTH CAROLINA LATE THIS
AFTERNOON ALONG A COLD FRONT THAT WILL BE MOVING THROUGH THE
REGION.
BEHIND THE FRONT TONIGHT WINDS WILL BE STRONG AND GUSTY. WIND
GUSTS OF 25 TO 25 KNOTS WILL BE COMMON IN THE MOUNTAINS...
ESPECIALLY ALONG THE RIDGES. MVFR CLOUDS WILL PERSIST AT KLWB AND
KBLF. WINDS WILL BEGIN TO DIMINISH WEDNESDAY MORNING AS HIGH
PRESSURE BUILDS INTO THE AREA.
HIGH PRESSURE AND VFR CONDITIONS WILL CONTINUE INTO THURSDAY.
THE WEATHER WILL BE DETERIORATING FOR THE WEEKEND AS NEXT LOW
PRESSURE SYSTEM MOVES IN FROM THE WEST WITH PRECIPITATION AND MVFR
OR LOWER CONDITIONS EXPECTED. A COLD FRONT WITH SEVERAL WAVES OF
LOW PRESSURE ALONG IT WILL TRAVEL EAST AND ADVANCE THROUGH OUR
REGION BY SUNDAY NIGHT.
&&
.RNK WATCHES/WARNINGS/ADVISORIES...
VA...NONE.
NC...NONE.
WV...NONE.
&&
$$
SYNOPSIS...AMS
NEAR TERM...AMS
SHORT TERM...DS
LONG TERM...KK
AVIATION...AMS
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
408 AM CST TUE DEC 17 2013
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 408 AM CST TUE DEC 17 2013
FORECAST CONCERNS ARE ON SNOW CHANCES TODAY. FOCUS THEN QUICKLY TURNS
TO STORM SYSTEM IMPACTING THE REGION THURSDAY INTO THURSDAY NIGHT
WITH THE POTENTIAL FOR LIGHT FREEZING RAIN AND SNOW.
AT 3 AM...WATER VAPOR IMAGERY SHOWED A WEAK SHORTWAVE PUSHING ACROSS
THE FORECAST AREA PRODUCING LIGHT SNOW AS IT MOVES THROUGH. THE
WAVE WILL EXIT THE AREA QUICKLY THIS MORNING BUT ANOTHER WAVE WAS
RIGHT BEHIND THE FIRST AND WAS MOVING ACROSS EASTERN NORTH DAKOTA.
THIS SECOND WAVE WILL BRING COLDER AIR ALOFT WITH IT...WITH 850 MB
TEMPERATURES GOING FROM -7C OVER THE AREA EARLY THIS MORNING TO
-17C BY LATE THIS AFTERNOON. THIS COLDER AIR ALOFT WILL STEEPEN
THE 1000-850 MB LAPSE RATES...LEADING TO SCATTERED SNOW SHOWERS
AND GUSTY WINDS FROM LATE THIS MORNING THROUGH THE AFTERNOON
HOURS. THE MOISTURE LOOKS LIMITED OVER SOUTHEAST MINNESOTA AND
NORTHEAST IOWA...ESPECIALLY WEST OF HIGHWAY 52. AREAS EAST OF
HIGHWAY 52 THROUGH WESTERN INTO CENTRAL WISCONSIN CAN EXPECT A FEW
PASSING SNOW SHOWERS TODAY WITH THE POTENTIAL TO PICK UP A FEW
TENTHS OF ACCUMULATION. LOCATIONS OVER CENTRAL INTO NORTH CENTRAL
WISCONSIN HAVE THE BEST CHANCES OF SEEING SOME LIGHT
ACCUMULATIONS. OTHERWISE...NORTHWEST WINDS WILL PICK UP TODAY INTO
THE 15 TO 25 MPH RANGE WITH SOME GUSTS AROUND 35 MPH OVER THE OPEN
AREAS OF SOUTHEAST MINNESOTA AND NORTHEAST IOWA. THESE WINDS WILL
PRODUCE SOME PATCHY BLOWING SNOW AND AREAS OF DRIFTING SNOW WHICH
COULD LEAD TO SOME SLICK SPOTS ON AREA ROADS. HIGH PRESSURE MOVES
OVER THE REGION TONIGHT WITH QUIET WEATHER EXPECTED. PLAN ON A
CHILLY NIGHT WITH LOWS RANGING FROM THE SINGLE DIGITS BELOW ZERO
OVER NORTH CENTRAL WISCONSIN TO THE TEENS ACROSS NORTHEAST IOWA.
THESE LOWS SHOULD OCCUR EARLY IN THE NIGHT. A WARM FRONT THEN
PUSHES ACROSS THE UPPER MISSISSIPPI RIVER VALLEY LATE TONIGHT INTO
EARLY WEDNESDAY MORNING AS A TROUGH DIVES INTO THE THE WEST COAST.
TEMPERATURES ARE EXPECTED TO GRADUALLY RISE EARLY WEDNESDAY
MORNING IN THE WAKE OF THE FRONT.
.LONG TERM...(WEDNESDAY THROUGH MONDAY)
ISSUED AT 408 AM CST TUE DEC 17 2013
LOW PRESSURE WILL DEVELOP OVER THE NORTHERN PLAINS ON
WEDNESDAY...LEADING TO A TIGHT PRESSURE GRADIENT OVER THE UPPER
MISSISSIPPI RIVER VALLEY. SOUTH/SOUTHWEST WINDS AHEAD OF THE LOW
WILL HELP TO USHER IN A WARMER AIRMASS. 850 MB TEMPERATURES START
OUT AT - 3C EARLY WEDNESDAY MORNING BUT THEN WARM TO +7C BY EARLY
WEDNESDAY EVENING. THE WARM AIR STAYS WELL ALOFT THROUGH THE DAY
BUT WE SHOULD STILL SEE HIGH TEMPERATURES WARM INTO THE 30S ACROSS
MUCH OF THE FORECAST AREA. THE ONLY EXCEPTION WILL BE OVER NORTH
CENTRAL WISCONSIN WHERE HIGHS ARE EXPECTED TO REACH INTO THE MID
20S.
A FRONTAL BOUNDARY THEN SLIDES SOUTH ACROSS THE AREA LATE
WEDNESDAY NIGHT INTO THURSDAY MORNING AS A TROUGH CONTINUES TO
DEEPEN OVER THE SOUTHWEST CONUS. THE FRONT IS EXPECTED TO STALL
OVER CENTRAL IOWA THROUGH SOUTH CENTRAL WISCONSIN. THE BOUNDARY
WILL INTERACT WITH A SHORTWAVE MOVING ACROSS THE NORTHERN PLAINS
AND THE RIGHT ENTRANCE REGION OF A 250 MB JET TO PRODUCE LIGHT
SNOW AND FREEZING DRIZZLE FROM THURSDAY AFTERNOON THROUGH THURSDAY
NIGHT. FORECAST SOUNDINGS SHOW ICE ALOFT FOR LOCATIONS NORTH OF
INTERSTATE 90 BY THE TIME THE PRECIPITATION DEVELOPS LATE IN THE
AFTERNOON. HOWEVER...FOR AREAS SOUTH OF INTERSTATE 90 THERE ISN/T
ICE ALOFT WITH SOUNDINGS SHOWING A NEARLY SATURATED LAYER FROM THE
SURFACE THROUGH 2KFT WITH WEAK OMEGA WITHIN THIS LAYER. THIS
SHOULD LEAD TO AREAS OF FREEZING DRIZZLE OVER NORTHEAST IOWA INTO
SOUTHWEST WISCONSIN EARLY THURSDAY MORNING. THE FREEZING DRIZZLE
SHOULD GRADUALLY SWITCH OVER TO SNOW THURSDAY NIGHT AS COOLER AIR
MOVES IN FROM THE NORTH AND SATURATION OCCURS ALOFT. WILL HAVE TO
KEEP A VERY CLOSE EYE ON THE FORECAST MODELS THE NEXT FEW RUNS.
THE ECMWF/GEM/GFS ARE IN AGREEMENT WITH THIS SCENARIO BUT THE NAM
IS SHOWING THE FREEZING DRIZZLE DEVELOPING LATE WEDNESDAY NIGHT
OVER NORTHEAST IOWA INTO FAR SOUTHWEST WISCONSIN. THE 17.06 NAM IS
NOW SHOWING A DRIZZLE SIGNATURE IN THE QPF FIELDS OVER THESE
AREAS. WILL LEAN TOWARD THE ECMWF/GEM/GFS. HEADLINES MAY BE NEEDED
OVER THESE AREAS FOR LIGHT ICE ACCUMULATIONS WHICH COULD LEAD TO
DANGEROUS TRAVEL CONDITIONS. FORECAST MODELS ARE ALSO TRENDING A
LITTLE COOLER WITH TEMPERATURES ON THURSDAY WITH MOST OF THE AREA
NOT GETTING ABOVE THE FREEZING MARK...WHICH RAISES ADDITIONAL
CONCERN FOR THE FREEZING DRIZZLE POTENTIAL. PLAN ON AREAS OF FOG
WEDNESDAY NIGHT THROUGH THURSDAY FOR AREAS ALONG AND SOUTH OF
INTERSTATE 90. THE FOG MAY BE DENSE AT TIMES...ESPECIALLY ACROSS
NORTHEAST IOWA AND FAR SOUTHWEST WISCONSIN. THE PRECIPITATION
SHOULD TURN OVER TO ALL SNOW BY EARLY FRIDAY MORNING. AT THIS TIME
IT APPEARS SNOW ACCUMULATIONS OF 1 TO 3 INCHES ARE POSSIBLE ALONG
AND NORTH OF I-90. A GLAZE TO AROUND A TENTH OF AN INCH OF ICING
IS POSSIBLE SOUTH OF I-90. ONCE THE FREEZING DRIZZLE SWITCHES OVER
TO SNOW...ACCUMULATIONS OF AROUND 1/2 INCH ARE POSSIBLE. THERE IS
CONSIDERABLE UNCERTAINTY REGARDING THE TIMING AND PLACEMENT OF THE
PRECIPITATION SO WILL HAVE TO KEEP A CLOSE EYE ON MODEL TRENDS
TODAY AND TONIGHT.
PRECIPITATION WILL END EARLY ON FRIDAY AS THE SYSTEM EXITS.
SLIGHTLY COOLER TEMPERATURES MOVE BACK INTO THE REGION FOR THIS
WEEKEND WITH HIGHS IN THE UPPER TEENS TO MID 20S BOTH FRIDAY AND
SATURDAY. PLAN ON OVERNIGHT LOWS DIPPING INTO THE SINGLE DIGITS. A
FEW WEAK DISTURBANCES COULD BRING SOME LIGHT SNOW TO THE AREA BUT
ACCUMULATIONS APPEAR MINOR AT THIS TIME. A STRONGER SYSTEM THEN
LIFTS NORTHEAST OUT OF MEXICO SATURDAY AND HEADS FOR THE OHIO RIVER
VALLEY LATE SATURDAY NIGHT INTO SUNDAY MORNING. THIS SYSTEM WILL
JUST GLANCE SOUTHWEST SECTIONS OF THE FORECAST AREA BRINGING LIGHT
SNOW TO PORTIONS OF NORTHEAST IOWA AND FAR SOUTHWEST WISCONSIN.
THERE WILL BE A BREAK IN THE PRECIPITATION CHANCES SUNDAY NIGHT
BEFORE ANOTHER WEAK SYSTEM MOVES THROUGH ON MONDAY BRINGING SLIGHT
CHANCES FOR LIGHT SNOW. IT WILL REMAIN ON THE COOL SIDE FOR THIS
TIME OF YEAR GOING INTO NEXT WEEK WITH HIGHS IN THE TEENS AND LOWS
IN THE SINGLE DIGITS.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z TUESDAY NIGHT)
ISSUED AT 1140 PM CST MON DEC 16 2013
THE NEXT BAND OF LIGHT SNOW WAS STARTING TO TAKE SHAPE OVER
CENTRAL AND NORTHERN MINNESOTA. THE SHORT WAVE TROUGH WITH THIS
BAND OF SNOW LOOKS TO TRACK FARTHER TO THE NORTH THAN PREVIOUSLY
EXPECTED. THIS HAS RESULTED IN A NORTHWARD SHIFT OF WHERE THE SNOW
SHOULD FALL AS WELL AND IT NOW COULD BE QUITE POSSIBLE THAT
NEITHER TAF SITE COULD SEE ANY SNOW. KLSE LOOKS TO HAVE A SLIGHTLY
BETTER CHANCE OF BEING BRUSHED BY THE SOUTHERN EXTENT OF THE SNOW
BAND AND HAVE SHOWN A SHORT PERIOD OF PREVAILING MVFR WITH THE
POSSIBILITY OF IFR...BUT CONFIDENCE IS NOT HIGH IN THIS AT ALL.
FOR KRST...HAVE GONE TO PREVAILING VFR OVERNIGHT WITH A
POSSIBILITY OF MVFR IF THE SNOW BAND CAN REACH THE AIRPORT. THE
SNOW CHANCES WILL END BEFORE SUNRISE AS A COLD FRONT GOES
THROUGH. THE 17.00Z NAM AND 18.03Z RAP NOW BOTH SHOW THE INVERSION
HOLDING TOUGH BEHIND THE FRONT UNTIL MID MORNING. ONCE THE
INVERSION MIXES OUT...GOOD LOW LEVEL LAPSE RATES DEVELOP THAT WILL
ALLOW FOR SUSTAINED NORTHWEST WINDS BETWEEN 15 AND 20 KNOTS WITH
GUSTS OF BETWEEN 25 AND 30 KT. THIS WILL LIKELY PRODUCE A LOT OF
DRIFTING SNOW AND POSSIBLY A LITTLE BIT OF BLOWING SNOW AT KRST.
THERE SHOULD ALSO BE ENOUGH RESIDUAL LOW LEVEL MOISTURE TO ALLOW
A MVFR CEILING TO DEVELOP ON TOP OF THE INSTABILITY LAYER. THE
INVERSION WILL REDEVELOP EARLY TUESDAY EVENING ALLOWING THE WINDS
TO SETTLE DOWN TO AROUND 10 KNOTS ENDING THE BLOWING SNOW AND MVFR
CEILINGS.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
WI...NONE.
MN...NONE.
IA...NONE.
&&
$$
SHORT TERM...WETENKAMP
LONG TERM...WETENKAMP
AVIATION...04
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
1140 PM CST MON DEC 16 2013
.SHORT TERM...(TONIGHT THROUGH WEDNESDAY)
ISSUED AT 341 PM CST MON DEC 16 2013
LATEST WATER VAPOR SATELLITE IMAGERY SHOWING UPPER LEVEL TROUGH OVER
EASTERN HALF OF THE UNITED STATES AND SEVERAL WEAK SHORTWAVE TROUGHS
EMBEDDED IN THE NORTHWEST FLOW ALOFT FROM THE CANADIAN ROCKIES INTO
THE GREAT LAKES REGION. FIRST IMPULSE AFFECTING THE FORECAST AREA
TODAY IS PRODUCING BRIEF MODERATE HEAVY SNOW BANDS...THIS IS IN
RESPONSE TO STRONG ISENTROPIC LIFT AT 285K SURFACE AND QG FORCING
AT 850-700MB LAYER
THE LATEST 16.12Z GFS/NAM ARE IN GOOD AGREEMENT IN MOVING NEXT
IMPULSE FROM THE SOUTHERN CANADIAN PLAINS INTO THE FORECAST AREA
TONIGHT. THE 16.12Z GFS/NAM BEGIN TO DIVERGE SIGNIFICANTLY ON
PLACEMENT AND MOVEMENT OF SURFACE FRONT/SURGE OF WARMER AIR ALOFT
ADVECTING INTO THE REGION AFTER 12Z WEDNESDAY...WHERE THE NAM IS
MUCH MORE PROGRESSIVE WITH THE WARMER AIR THAN THE GFS. THIS WILL
HAVE IMPACTS ON PRECIPITATION TYPES ACROSS THE FORECAST AREA
THURSDAY.
TONIGHT...BOTH THE 16.12Z GFS/NAM SHOWING STRONG ISENTROPIC LIFT AT
285K SURFACE AND STRONG PV ADVECTION AT 500-300MB LAYER IN
ASSOCIATION WITH NEXT SHORTWAVE TROUGH MOVING OVER FORECAST
AREA...MAINLY AFTER 03Z TUESDAY. THE GFS/NAM SUGGEST THE VERTICAL
MOTION IS AT OR AROUND THE DENDRITIC GROWTH ZONE...HOWEVER...WITH
THE LIFT AND FORCING MOVING ACROSS THE FORECAST AREA QUICKLY.
SNOWFALL AMOUNTS SHOULD RANGE FROM AROUND A HALF OF AN INCH
ACROSS NORTHEAST IOWA TO AROUND TWO INCHES ACROSS CENTRAL
WISCONSIN.
ALONG WITH THE FRESH SNOW...SURFACE PRESSURE GRADIENT TIGHTENS ON
THE BACKSIDE OF THE SHORTWAVE TROUGH AFTER 06Z TUESDAY. THIS WILL
INCREASE WINDS ACROSS THE FORECAST AREA INTO 10 TO 20 KNOTS RANGE AND
GUSTS UP TO 20 TO 27 KNOTS. THIS WILL CREATE SOME AREAS/PATCHY
BLOWING SNOW MAINLY OVER THE HIGHER TERRAIN AND OPEN AREAS OF
SOUTHEAST MINNESOTA AND NORTHEAST IOWA INTO TUESDAY MORNING.
SURFACE WARM FRONT/STRONG WARM AIR ADVECTS INTO THE AREA TUESDAY
NIGHT INTO WEDNESDAY. THE NAM IS MORE AGGRESSIVE ADVECTING THE
WARMER AIR INTO THE REGION...WITH THE NAM 925MB TEMPERATURES
WARMING TO PLUS 2 TO 3 DEGREES CELSIUS OVER THE SOUTHERN FORECAST
AREA. THE 16.12Z GFS MUCH COOLER WITH 925MB TEMPERATURES MINUS 3
TO MINUS 4 DEGREES CELSIUS OVER THE SOUTHERN FORECAST AREA. DUE TO
THE FRESH SNOW COVER AND MODEL DIFFERENCES ON POSITION OF SURFACE
WARM FRONT/WARMER AIR ALOFT CONFIDENCE IN TEMPERATURES IS LOW.
KEPT A BLEND OF TEMPERATURES AT THIS TIME FRAME.
.LONG TERM...(WEDNESDAY NIGHT THROUGH MONDAY)
ISSUED AT 341 PM CST MON DEC 16 2013
MAIN FOCUS IS WEDNESDAY NIGHT INTO THURSDAY WITH WEAK SURFACE
LOW/SHORTWAVE TROUGH EJECTING OUT INTO THE CENTRAL PLAINS STATES.
THE LATEST 16.12Z GFS/NAM ARE INDICATING NEAR SURFACE BOUNDARY LAYER
SATURATING UNDER STRONG INVERSION WEDNESDAY NIGHT INTO THURSDAY
MORNING. THE 16.12Z GFS/NAM BUFKIT SOUNDINGS OVER THE SOUTHERN
FORECAST AREA SHOW WEAK VERTICAL MOTION AT THE TOP OF THE INVERSION
LAYER AND NO ICE INTRODUCTION BELOW THE INVERSION. DEPENDING ON
TEMPERATURES AT SURFACE...EXPECT DRIZZLE OR FREEZING DRIZZLE TO
DEVELOP OVER THE SOUTHERN FORECAST AREA. PER BUFKIT SOUNDINGS AFTER
18Z THURSDAY...DEEPER SATURATION OCCURS AND ALLOWS RAIN TO SPREAD
ACROSS THE SOUTHERN FORECAST AREA. DUE TO THE FROZEN GROUND AND
POSSIBLY TEMPERATURES NEAR OR A DEGREE OR TWO BELOW
FREEZING...FREEZING RAIN IS A POSSIBLE OVER THE SOUTHERN HALF OF THE
FORECAST AREA.
THURSDAY NIGHT INTO MONDAY...MAIN FORECAST CONCERNS ARE
PRECIPITATION CHANCES THROUGH PERIOD. THE 16.00Z GFS/ECMWF/GEM ARE
IN GOOD AGREEMENT IN DIGGING UPPER LEVEL TROUGH AND DEVELOPING
NORTHWEST FLOW ALOFT OVER THE UPPER GREAT LAKES REGION THIS WEEKEND
AND INTO EARLY NEXT WEEK. THE BIGGEST DIFFERENCES IN THE MODELS ARE
TIMING OF THE UPPER LEVEL/SURFACE LOW EJECTING OUT INTO THE CENTRAL
PLAINS/GREAT LAKES REGION THIS WEEKEND AND SHORTWAVE TROUGH EMBEDDED
IN THE NORTHWEST FLOW ALOFT EARLY NEXT WEEK. THE 16.00Z GFS/ECMWF
ARE IN DECENT AGREEMENT IN TRACKING FIRST WEAK IMPULSE INTO NORTHERN
ILLINOIS AND SOUTHERN LAKE MICHIGAN THURSDAY NIGHT AND PLACING
ASSOCIATED DEFORMATION BAND OF PRECIPITATION ACROSS NORTHERN
WISCONSIN. AT THIS TIME...NOT CONFIDENT ON HIGH CHANCES OF
PRECIPITATION THURSDAY NIGHT ACROSS FORECAST AREA...AS THE GFS/ECMWF
DPROG/DT TRENDING THE MAIN LIFT AND FORCING NORTH AND SOUTH OF
FORECAST AREA THE LAST COUPLE OF RUNS. THE MODELS ARE IN AGREEMENT
TRACKING THIS WEEKEND UPPER LEVEL/SURFACE LOW SOUTH OF FORECAST AREA
AND ALLOWS UPPER LEVEL TROUGH TO DIG OVER THE GREAT LAKES REGION AND
DEVELOP NORTHWEST FLOW OVER FORECAST AREA. THIS WILL CONTINUE TO
ADVECT IN UNSEASONABLY COLD ARCTIC AIRMASS INTO THE FORECAST AREA
LATE THIS WEEKEND INTO EARLY NEXT WEEK. THE 16.00Z MODELS SHOW
DIFFERENCES IN TIMING OF SHORTWAVE TROUGH EMBEDDED IN NORTHWEST FLOW
TO MOVE ACROSS THE GREAT LAKES REGION EARLY NEXT WEEK. WITH MODELS
INDICATING ENOUGH LIFT AND MOISTURE ASSOCIATED WITH SHORTWAVE
TROUGH...SMALL PRECIPITATION CHANCES ARE WARRANTED.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z TUESDAY NIGHT)
ISSUED AT 1140 PM CST MON DEC 16 2013
THE NEXT BAND OF LIGHT SNOW WAS STARTING TO TAKE SHAPE OVER
CENTRAL AND NORTHERN MINNESOTA. THE SHORT WAVE TROUGH WITH THIS
BAND OF SNOW LOOKS TO TRACK FARTHER TO THE NORTH THAN PREVIOUSLY
EXPECTED. THIS HAS RESULTED IN A NORTHWARD SHIFT OF WHERE THE SNOW
SHOULD FALL AS WELL AND IT NOW COULD BE QUITE POSSIBLE THAT
NEITHER TAF SITE COULD SEE ANY SNOW. KLSE LOOKS TO HAVE A SLIGHTLY
BETTER CHANCE OF BEING BRUSHED BY THE SOUTHERN EXTENT OF THE SNOW
BAND AND HAVE SHOWN A SHORT PERIOD OF PREVAILING MVFR WITH THE
POSSIBILITY OF IFR...BUT CONFIDENCE IS NOT HIGH IN THIS AT ALL.
FOR KRST...HAVE GONE TO PREVAILING VFR OVERNIGHT WITH A
POSSIBILITY OF MVFR IF THE SNOW BAND CAN REACH THE AIRPORT. THE
SNOW CHANCES WILL END BEFORE SUNRISE AS A COLD FRONT GOES
THROUGH. THE 17.00Z NAM AND 18.03Z RAP NOW BOTH SHOW THE INVERSION
HOLDING TOUGH BEHIND THE FRONT UNTIL MID MORNING. ONCE THE
INVERSION MIXES OUT...GOOD LOW LEVEL LAPSE RATES DEVELOP THAT WILL
ALLOW FOR SUSTAINED NORTHWEST WINDS BETWEEN 15 AND 20 KNOTS WITH
GUSTS OF BETWEEN 25 AND 30 KT. THIS WILL LIKELY PRODUCE A LOT OF
DRIFTING SNOW AND POSSIBLY A LITTLE BIT OF BLOWING SNOW AT KRST.
THERE SHOULD ALSO BE ENOUGH RESIDUAL LOW LEVEL MOISTURE TO ALLOW
A MVFR CEILING TO DEVELOP ON TOP OF THE INSTABILITY LAYER. THE
INVERSION WILL REDEVELOP EARLY TUESDAY EVENING ALLOWING THE WINDS
TO SETTLE DOWN TO AROUND 10 KNOTS ENDING THE BLOWING SNOW AND MVFR
CEILINGS.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
WI...NONE.
MN...NONE.
IA...NONE.
&&
$$
SHORT TERM...DTJ
LONG TERM...DTJ
AVIATION...04
AREA FORECAST DISCUSSION
NWS TAUNTON MA
430 AM EST THU DEC 19 2013
.SYNOPSIS...
DRY AND MILDER WEATHER EXPECTED TODAY AS A COLD FRONT STALLS TO
OUR NORTH. THIS STALLED FRONT WILL RESULT IN PERIODS OF UNSETTLED
WEATHER FRI NIGHT THROUGH EARLY MON. DRIER AND COOLER WEATHER
ARRIVES EARLY NEXT WEEK.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
415 AM UPDATE...MADE SOME TWEAKS TO SKY COVER BASED ON OBSERVED
TRENDS. TWEAKED TEMPERATURES BASED ON THE CLOUDS ALREADY IN
PLACE...AS MOST LOCATIONS INDICATING A REBOUND FROM THEIR
RESPECTIVE MIN TEMPERATURES AS THE CLOUDS ARRIVE.
FOR THE REST OF TODAY...EXPECTING A DRY DAY WITH A HIGH PRESSURE
LOCATED ALONG THE SOUTHEAST USA COAST. THIS WILL RESULT IN A WEST
TO SOUTHWEST FLOW TODAY.
3.9 MICRON SATELLITE IMAGERY SHOWING ABUNDANT LOW-LEVEL MOISTURE
STREAMING EAST FROM THE GREAT LAKES THIS MORNING. THESE CLOUDS
HAVE SINCE COVERED MOST OF SOUTHERN NEW ENGLAND. WEST FLOW...
ALBEIT RELATIVELY LIGHT...THIS MORNING WILL INDUCE SOME
DOWNSLOPING. THUS THINKING THERE SHOULD BE MORE SUN THAN CLOUDS
TODAY...ONCE THE CURRENT CLOUDS IN OUR REGION MOVE EAST. THE
LATEST VERSION OF THE RAP SEEMED TO BE HANDLING THIS SITUATION
WELL...SO RELIED ON IT FOR TIMING.
IT WILL BE A LITTLE WARMER TODAY THAN YESTERDAY WITH THE SUNSHINE
AND WEST TO SOUTHWEST WINDS.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH 6 PM FRIDAY/...
A FRONTAL BOUNDARY WILL SLOWLY MOVE SOUTH THROUGH NORTHERN NEW
ENGLAND TONIGHT. THERE IS STILL SOME QUESTION AS TO EXACTLY HOW
MUCH PROGRESS IT WILL MAKE IN OUR DIRECTION. DEEPER MOISTURE STILL
SHOULD REMAIN NORTH OF OUR REGION FOR MOST OF TONIGHT. SO ONLY
HAVE A CHANCE OF SOME SOME PRECIPITATION VERY LATE TONIGHT INTO
FRIDAY NORTH OF I-90...MAINLY DURING THE DAYTIME FRIDAY.
THE TIMING OF THIS FRONT AND PRECIPITATION WILL BE CRUCIAL FOR
DETERMINING TYPE. THINKING THERE IS A POSSIBILITY FOR SOME LIGHT
ICING ACROSS SOUTHERN NH LATE TONIGHT...BUT IT SHOULD NOT BE VERY
WIDESPREAD. AS SUCH...HOLDING OFF ON ISSUING ANY FREEZING RAIN
ADVISORIES AT THIS TIME. NEXT SHIFT WILL HAVE TO MONITOR THIS
SITUATION. EVENTUALLY ANY PRECIPITATION IN OUR REGION SHOULD
TRANSITION TO ALL RAIN AS TEMPERATURES CONTINUE TO RISE FRIDAY
MORNING. WARMING TREND CONTINUES...WITH HIGHS GENERALLY IN THE 40S
FOR THE FIRST TIME IN SEVERAL DAYS FOR MOST OF THE INTERIOR.
&&
.LONG TERM /FRIDAY NIGHT THROUGH WEDNESDAY/...
* UNSETTLED WEATHER OVER THE WEEKEND
* DRIER...COOLER WEATHER EXPECTED EARLY NEXT WEEK
00Z NAM AND GFS ARE MORE PROGRESSIVE THAN THE ECMWF/UKMET/CANADIAN
WITH WAVES OF LOW PRESSURE MOVING ALONG A COLD FRONT STRETCHED
ACROSS NORTHERN NEW ENGLAND FRIDAY NIGHT AND SATURDAY. WITH THE
SUPPORT OF WPC...AM LEANING AWAY FROM THE NAM/GFS SOLUTION FOR THIS
PERIOD OF THE FORECAST. SUNDAY AND BEYOND...MODELS ARE IN
REMARKABLY GOOD AGREEMENT ON THE GENERAL SYNOPTIC SCALE PATTERN
THROUGH THE LONG TERM. WHILE THE MODELS DO SEEM TO BE NARROWING IN
THEIR RANGE OF SOLUTIONS...THERE IS STILL QUITE A BIT OF UNCERTAINTY
WHEN IT COMES TO THE TEMPERATURE PROFILE SATURDAY NIGHT AND SUNDAY.
THESE TEMPERATURE PROFILES...PARTICULARLY THE SURFACE TEMPERATURES
WILL PLAY A BIG ROLE IN PTYPE. AT THIS POINT...LOOKS LIKE ANY
FROZEN/FREEZING PRECIPITATION WILL BE LIMITED TO SOUTHERN NEW
HAMPSHIRE. THE ARCTIC FRONT MOVES THROUGH SOUTHERN NEW ENGLAND LATE
SUNDAY INTO EARLY MONDAY. THEN COOLER...DRIER WEATHER IS FORECAST
TO PERSIST THROUGH CHRISTMAS DAY.
FRIDAY NIGHT THROUGH SATURDAY...LIGHT PRECIPITATION IS POSSIBLE
ACROSS THE NORTHERN ZONES AS LOW PRESSURE MOVES THROUGH NORTHERN NEW
ENGLAND ALONG THE FRONT. QPF FORECASTS ARE LESS THAN A TENTH OF AN
INCH DURING THIS TIME. HOWEVER...LOOKS THAT SURFACE TEMPERATURES IN
SOUTHERN NEW HAMPSHIRE IN PARTICULAR ARE LIKELY TO BE BELOW
FREEZING. SO THERE IS LIKELY TO BE A PERIOD OF FREEZING RAIN IN
THIS AREA. A VERY MINIMAL TEMPERATURE CHANGE CAN MEAN THE
DIFFERENCE BETWEEN ICING AND REGULAR RAIN SO THIS WILL CONTINUE TO
BE MONITORED.
SATURDAY NIGHT THROUGH MONDAY MORNING...WHILE THE MODELS SEEM TO BE
TIGHTENING UP ON THEIR VARYING SOLUTIONS...THERE REMAINS SOME
UNCERTAINTY IN THE SURFACE TEMPERATURE FORECASTS. IT DOES LOOK LIKE
THERE IS POTENTIAL FOR A PERIOD OF FREEZING RAIN SOMEWHERE NORTH OF
ROUTE 2 IN MASSACHUSETTS AND INTO SOUTHERN NEW HAMPSHIRE. THIS SET
OF MODELS TOOK THE COLDER TEMPERATURES A BIT FARTHER NORTH THAN
PREVIOUS MODELS...KEEPING MOST...IF NOT ALL...OF THE CWA OUT OF THE
COLDER TEMPERATURES AND THE FREEZING RAIN. THIS BEING ONE OF THE
FIRST MODEL RUNS TO INDICATE THIS...HAVE USED A BLEND OF THE MODEL
CONSENSUS AND THE PREVIOUS FORECAST FOR THE SURFACE TEMPERATURES.
OTHERWISE...SUNDAY IS EXPECTED TO BE THE WARMEST DAY OF THE FORECAST
WITH TEMPERATURES IN THE 50S SURGING NORTHWARD TO THE MASS PIKE.
THE REST OF MONDAY THROUGH CHRISTMAS DAY...THE ARCTIC FRONT FINALLY
MOVES THROUGH SOUTHERN NEW ENGLAND MONDAY. COLD HIGH PRESSURE
BUILDS IN BEHIND THE FRONT WITH SUBSTANTIALLY COLDER TEMPERATURES
EXPECTED CHRISTMAS EVE AND DAY.
&&
.AVIATION /10Z THURSDAY THROUGH MONDAY/...
FORECASTER CONFIDENCE LEVELS...
LOW...LESS THAN 30 PERCENT.
MODERATE...30 TO 60 PERCENT.
HIGH...GREATER THAN 60 PERCENT.
NEAR TERM /THROUGH FRIDAY/...
HIGH CONFIDENCE IN VFR CONDITIONS FOR MUCH OF THE REGION TODAY.
SOME MVFR CIGS WILL AFFECT THE E SLOPES OF THE BERKSHIRES THIS
MORNING. MODERATE CONFIDENCE VFR TONIGHT...WITH THE POTENTIAL FOR
SOME MVFR CONDITIONS IN SHOWERS. ISOLATED POCKETS OF ICING
POSSIBLE NORTH OF KLWM-KFIT-KORE-KAQW. GUSTY SW WIND GUSTS UP TO
30 KT DEVELOPING AT KACK BY LATE MORNING.
KBOS TAF...HIGH CONFIDENCE IN TAF.
KBDL TAF...HIGH CONFIDENCE IN TAF.
OUTLOOK...FRIDAY NIGHT THROUGH MONDAY...
FRIDAY NIGHT THROUGH SATURDAY...MODERATE CONFIDENCE. MAINLY VFR.
SATURDAY NIGHT THROUGH EARLY MONDAY MORNING...LOW CONFIDENCE.
MVFR/IFR CONDITIONS DEVELOP IN MAINLY RAIN SHOWERS. FREEZING RAIN
IS POSSIBLE MAINLY THROUGH SOUTHERN NEW HAMPSHIRE.
MONDAY AFTERNOON/EVENING/NIGHT...HIGH CONFIDENCE. IMPROVEMENT TO
VFR BEHIND ARCTIC FRONT. WINDS SHIFT FROM SW TO NW.
&&
.MARINE...
FORECASTER CONFIDENCE LEVELS...
LOW...LESS THAN 30 PERCENT.
MODERATE...30 TO 60 PERCENT.
HIGH...GREATER THAN 60 PERCENT.
NEAR TERM /THROUGH FRIDAY/...HIGH CONFIDENCE
ANOTHER PULSE OF STRONG SW WINDS WILL DEVELOP LATER TODAY. NEAR
GALE FORCE GUSTS POSSIBLE OVER THE OUTER SOUTH COASTAL WATERS.
CONFIDENCE IN A PROLONGED PERIOD OF GALE FORCE GUSTS IS MODERATE
AT BEST. WINDS WILL DIMINISH TONIGHT AS PRESSURE GRADIENT
RELAXES. DECIDED TO REPLACE THE GALE WATCH WITH A HIGH END SMALL
CRAFT ADVISORY.
LATEST WNA WAVE HEIGHT GUIDANCE LOOKS SLIGHTLY UNDERDONE. WILL
MAKE SOME TWEAKS IN THE NEAR TERM TO BRING SEAS UP TO LATEST
MARINE REPORTS.
OUTLOOK...FRIDAY NIGHT THROUGH MONDAY...
SOUTHWESTERLY WINDS WITH PERIODS OF GUSTS UP TO 30 KTS PERSIST
THROUGH MUCH OF THE LONG TERM. WINDS SHIFT TO THE NORTHWEST AS AN
ARCTIC FRONT MOVES ACROSS THE WATERS MONDAY. WAVES BUILD AND
DIMINISH AS WAVES OF LOW PRESSURE MOVE ALONG AN ARCTIC FRONT THROUGH
NORTHERN NEW ENGLAND BUT GENERALLY REMAIN ABOVE 5 FEET ON THE OUTER
WATERS AT LEAST. MUCH OF THIS TIME WILL LIKELY NEED SMALL CRAFT
ADVISORIES UP FOR AT LEAST THE OUTER WATERS...BUT OVERALL CONFIDENCE
IS LOW ON TIMING.
&&
.BOX WATCHES/WARNINGS/ADVISORIES...
CT...NONE.
MA...NONE.
NH...NONE.
RI...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL 6 PM EST THIS EVENING FOR
ANZ231>234-251.
SMALL CRAFT ADVISORY FROM 8 AM THIS MORNING TO 5 PM EST THIS
AFTERNOON FOR ANZ230-236.
SMALL CRAFT ADVISORY UNTIL 6 AM EST FRIDAY FOR ANZ235-237.
SMALL CRAFT ADVISORY UNTIL 10 PM EST THIS EVENING FOR ANZ250.
SMALL CRAFT ADVISORY UNTIL 6 PM EST FRIDAY FOR ANZ254>256.
&&
$$
SYNOPSIS...BELK/RLG
NEAR TERM...BELK
SHORT TERM...BELK
LONG TERM...RLG
AVIATION...BELK/RLG
MARINE...BELK/RLG
Area Forecast Discussion
National Weather Service Lincoln IL
343 AM CST Thu Dec 19 2013
.DISCUSSION...
ISSUED 311 AM CST Thu Dec 19 2013
High pressure sliding to the southeastern corner of the country as
a cold front slowly approaches the Midwest. A vigorous wave is
digging in over the southwest and translating into more
southwesterly flow over the region. Temperatures slowly increasing
as the airmass modifies with persistent moisture and warm air
advection. Cold front on the way to move through the area late
tonight and tomorrow morning...eventually stalling invof the Ohio
River Valley. Initial fropa less of an issue, with predominantly
rain for ILX. However, the front will provide a focus for precip
in the southeast...and a path to follow for the next wave ejecting
out of the southwest. Models have been very inconsistent with
track and thermodynamics...and are starting to waiver in the
strength overall. That being said, the trend to a more northerly
track is reflected in the forecast.
SHORT TERM...Today and Tonight...
Warmer as southerly winds usher in temps into the 40s. Overnight
expected to remain mostly above freezing as well. Pops return to
the forecast late this afternoon in the extreme NW as rain makes
its way into Central Illinois. Rain chances continue through the
overnight with the front as the winds slowly shift to
northwesterly behind the front and cooler air filters in. Cold air
not moving in very quickly however as the boundary is relatively
weak/the thermal gradient is less significant. For now, the
initial front is dominated by rain. Problems creep in after
midnight tomorrow night as temperatures finally drop and the
precip changes over to freezing rain for the northern half of the
state.
LONG TERM...Saturday through Wednesday...
Models still a problem, lacking continuity and consistency. Trend
to the north is pronounced enough to be reflected however. This
same trend broadens the developing warm sector and reduces the
coldest air. Ice/freezing rain confined mostly to NW of the
Illinois River Valley for Saturday morning, though a transition to
liquid will likely fall between the valley and the I-55 corridor.
Freezing rain in the NW and rain in the SE will continue through
the afternoon and evening before making the transition over to
snow for after midnight and Sunday. All this precip type/wintry
mix determination a low confidence forecast and likely to shift
with subsequent model runs. However, confidence is increasing on
the prolonged and heavy rain event setting up btwn I-70 corridor
and the Ohio River Valley. 2-3 inches of rainfall from Friday
night through Sunday morning will result in an increased flood
risk, particularly with partially frozen ground...already
saturated from recent snowmelt. Flood watch issued with the
forecast from Christian County to Vermilion County and points SE.
Monday bitterly cold on the back side of this system with highs in
the teens... and Monday night sinking into the single digits with light
winds and very little cloud cover. Remains of the forecast left to
the AllBlend for temps, and dry as high pressure returns to the
Midwest until the next systems arrival late Wednesday.
HJS
&&
.AVIATION...
ISSUED 1110 PM CST Wed Dec 18 2013
Little change from earlier thinking this evening, the main
challenge will be timing of the IFR/LIFR cigs and vsbys into
the forecast area on Thursday. Tight pressure gradient over
the state this evening resulted in rather gusty south winds.
The surface winds are expected to diminish some during the
early morning hours, however, the latest short term forecasts
suggest the LLWS in the 1500 ft level will continue thru 12z.
A cold front over the northwest half of Iowa will push to the
Mississippi River by dawn Thursday and then slowly edge east
into our area during the day. The persistent southerly winds
will aid in transporting higher moisture northeast over the
colder/snow covered areas of central IL, which will lead to
widespread low cigs and vsbys, especially during the afternoon
and evening. Confidence on the timing of the lower cigs and
vsbys in our area is not that great at this time as most models
have been too aggressive in developing the IFR cigs and vsbys.
However, the HRRR model has been quite consistent in keeping
the low cigs out thru the morning with development taking place
by afternoon from west to east. Will tend to lean more on that
model`s timing at this point.
Surface winds will remain out of the south at 12 to 17 kts into
the early morning hours with a gradual decrease in the sustained
winds by morning. Southerly winds will hold over the area thru
Thursday with speeds of 8 to 13 kts. Forecast soundings indicate
the potential for some light rain or drizzle with the lower cigs
and vsbys Thursday evening.
Smith
&&
.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
1206 AM CST THU DEC 19 2013
.DISCUSSION...
810 PM CST
FOR EVENING UPDATE...
MAIN SHORT TERM FORECAST CONCERNS FOCUS ON TEMPERATURE TRENDS WITH
BREEZY SOUTH WINDS AND WARM ADVECTION...AND CLOUD TRENDS WITH MODEL
FORECASTS CONTINUING TO DEPICT STRATUS DEVELOPMENT OVERNIGHT. HAVE
MADE SOME MINOR CHANGES TO GOING FORECAST TO LOWER MIN TEMPS A BIT
ESPECIALLY ACROSS NORTH CENTRAL IL WHERE THEY/VE FALLEN OFF THIS
EVENING...AND TO REDUCE SKY COVER A BIT UNTIL LATE/TOWARD MORNING.
SURFACE LOW PRESSURE WAS OVER NORTHERN WISCONSIN AT 02Z/8 PM CST IN
ASSOCIATION WITH A QUICK MOVING SHORT WAVE PROPAGATING ACROSS THE
UPPER MISSISSIPPI VALLEY AND NORTHERN LAKES REGION. TIGHT PRESSURE
GRADIENT BETWEEN THIS LOW AND HIGH PRESSURE OVER THE SOUTHEASTERN
STATES HAS RESULTED IN BREEZY SOUTH-SOUTHWEST WINDS ACROSS THE
REGION...ESPECIALLY ACROSS THE SOUTH/EAST CWA AT THIS HOUR CLOSER TO
WHERE STRONGER SURFACE PRESSURE FALLS WERE OCCURRING NOW OVER LOWER
MICH/INDIANA/OH. WINDS HAVE KEPT TEMPS NEARLY STEADY OR EVEN TO RISE
A DEGREE OR TWO...EXCEPT OVER NORTH CENTRAL IL WHERE WEAKENING
GRADIENT/WINDS AND MOSTLY CLEAR SKIES HAVE ALLOWED TEMPS TO FALL A
FEW DEGREES. EXPECT THIS WILL CONTINUE TO BE THE CASE OVERNIGHT AS
WINDS CONTINUE TO DIMINISH FROM THE NORTHWEST...AS SURFACE COLD
FRONTAL TROUGH SLOWLY APPROACHES BEHIND NORTHERN LAKES LOW. EXPECT
TO SEE TEMPS REMAIN FAIRLY STEADY NORTHWEST OVERNIGHT...RISING A BIT
IN THE EAST/SOUTHEAST COUNTIES AND LIKELY STAYING ABOVE FREEZING.
AS FOR CLOUDS...ONLY SOME PATCHY HIGH CIRRUS ACROSS THE REGION AT
THIS TIME. VARIOUS MODELS CONTINUE TO INDICATE DEVELOPMENT OF LOW
STRATUS FROM NORTHERN/NORTHWEST IL BACK INTO MISSOURI BY LATE
EVENING...THOUGH UPSTREAM 00Z SOUNDINGS FROM DVN/ILX/SGF/TOP ALL
VERY DRY IN THE LOW/MID LEVELS AND SUSPECT MODELS ARE OVER-DONE WITH
STRATUS AND POTENTIAL FOG DEVELOPMENT OVERNIGHT. GFS MAV GUIDANCE
MAY HAVE THE RIGHT IDEA...OF HOLDING OFF LOW CLOUD DEVELOPMENT LATER
THURSDAY...WHEN COLD FRONT STALLS ACROSS AREA AND HELPS TO POOL LOW
LEVEL MOISTURE ALONG IT. THEREFORE HAVE REDUCED SKY COVER PERCENTAGE
IN HOURLY GRIDS THROUGH 09Z OR SO...WITH INCREASING CLOUDINESS THEN
INTO THURSDAY MORNING.
RATZER
//PREV DISCUSSION...
305 PM CST
SHORT TERM (THROUGH FRIDAY NIGHT)...
STRENGTHENING SOUTHERLY WINDS ACROSS THE IN RESPONSE TO A
CLIPPER-LIKE SYSTEM TRACKING EAST ACROSS THE UPPER MISSISSIPPI
VALLEY HAS BEGUN THE PROCESS OF DRAGGING LOW LEVEL MOISTURE
NORTHWARD INTO MISSOURI AND IOWA. FARTHER EAST OVER OUR CWA
DEWPOINTS HAVE BEEN SLOW TO COME UP...WITH MODELS NOT HANDLING THE
RETURN OF LOW LEVEL MOISTURE PARTICULARLY WELL. OBSERVATIONAL TRENDS
THUS FAR TODAY ARE REALLY BEGINNING TO RAISE SOME SERIOUS DOUBTS
ABOUT THE TIMING OF THE DEVELOPMENT OF STRATUS AND POTENTIALLY FOG
ACROSS THE AREA. FORECAST SOUNDINGS FROM THE NAM AND GFS WOULD
SUGGEST STRATUS OVER THE AREA BY MID EVENING. MODELS SAY THAT THIS
STRATUS "SHOULD" BE BLOSSOMING OVER IOWA AND MISSOURI IN THE NEXT
HOUR OR TWO...BUT WITH SURFACE DEWPOINT DEPRESSIONS OF 10-15F OVER
THE SNOW PACK AND 20F+ JUST UPSTREAM I SUSPECT THIS PROCESS WILL BE
MUCH SLOWER THAN FORECAST BY THE MODELS. GIVEN DEWPOINTS JUST BARELY
FORECAST TO REACH FREEZING AND PROBABLY NOT UNTIL LATE
TONIGHT...SNOW MELT WONT BE A HUGE FACTOR TOWARD ADDING LOW LEVEL
MOISTURE AND AM PLANNING TO PUSH BACK STRATUS IN THE GRIDS AND
REMOVE DRIZZLE AND FOG TONIGHT.
AS CLIPPER TRACKS RAPIDLY EAST INTO THE NE CONUS ON THURSDAY A COLD
FRONT TRAILING WEST FROM THE LOW WILL BEGIN TO SAG SLOWLY SOUTHWARD
BECOMING INCREASINGLY ALIGNED WITH THE MID-UPPER LEVEL FLOW AND
LIKELY STALLING OUT OVER NORTHERN ILLINOIS THURSDAY. WEAK SHORTWAVE
EMANATING OUT OF THE AMPLIFYING WESTERN CONUS TROUGH WILL ENCOURAGE
A WEAK WAVE OF LOW PRESSURE TO TRACK NORTHEAST ALONG THE STALLED OUT
FRONT INTO CENTRAL ILLINOIS AND NORTHERN INDIANA THURSDAY NIGHT INTO
FRIDAY. LOW LEVEL BAROCLINIC ZONE WILL STRENGTHEN IN ADVANCE OF THIS
WAVE THURSDAY NIGHT WITH BACKING LOW LEVEL FLOW RESULTING IN
INCREASING ISENTROPIC ASCENT. ANTICIPATE LIGHT RAIN TO BREAK OUT
ALONG AND NORTH OF THIS SURFACE BOUNDARY ACROSS MUCH OF THE CWA LATE
THURSDAY AFTERNOON AND PARTICULARLY THURSDAY NIGHT. MODELS REMAIN
IN GREAT AGREEMENT IN KEEPING DEPTH OF MOISTURE SOMEWHAT SHALLOW
WITH FAIRLY DEEP LAYER OF DRY AIR IN THE MID LEVELS WHICH. THIS
DRY AIR ALOFT WILL LIKELY RESULT IN LITTLE/NO ICE BEING PRESENT IN
THE CLOUDS SO PRECIP FALLING SHOULD BE ALL LIQUID (DRIZZLE/LIGHT
RAIN).
STRENGTHENING NORTH WINDS TO THE NORTH OF THE BOUNDARY AND RESULTANT
COLD AIR ADVECTION LOOK TO SEND SFC TEMPS DROPPING BELOW FREEZING
THURSDAY NIGHT FROM THE NORTHERN SUBURBS WEST INTO NORTH CENTRAL
ILLINOIS. DESPITE ONLY SLIGHT LAYER OF ABOVE FREEZING TEMPS...THE
EXPECTED LACK OF ICE IN THE CLOUDS SHOULD RESULT IN A SWITCH OVER TO
LIGHT FREEZING RAIN AS TEMPS DROP BELOW FREEZING THURSDAY NIGHT.
WHILE QPF WILL BE LIGHT...ANY AMOUNT OF FREEZING RAIN IS ENOUGH TO
CAUSE PROBLEMS. LATER FORECASTS WILL PROBABLY HAVE TO FINE TUNE
THE LOCATION OF THE FREEZING LINE...BUT WOULD ANTICIPATE THAT A
FREEZING RAIN ADVISORY WILL EVENTUALLY BE NEEDED FOR AREAS MAINLY
WEST AND NORTH OF CHICAGO THURSDAY NIGHT INTO FRIDAY MORNING.
THE WEAK WAVE OF LOW PRESSURE WILL RIPPLE EAST OF THE AREA AND ALLOW
THE FRONT TO SAG A BIT SOUTH IN ITS WAKE FRIDAY. FORCING GENERALLY
LOOKS WEAK AND UNIMPRESSIVE...BUT GLOBAL MODELS INSIST ON SQUEEZING
OUT A FEW HUNDREDTHS OF AN INCH OF ADDITIONAL QPF FRIDAY. HAVE OPTED
TO HANG ON TO SOME VERY LOW CHANCE POPS FRIDAY INTO FRIDAY
NIGHT...BUT GENERALLY THINK THAT PRECIP SHOULD SHUT DOWN UNTIL THE
BIG BOY TO OUR SOUTHWEST COMES BARRELING OUT TOWARD THE AREA OVER
THE WEEKEND.
IZZI
THE BIG WEEKEND STORM...SATURDAY INTO SUNDAY...
A MAJOR PRECIPITATION EVENT IS BECOMING MORE LIKELY ACROSS THE AREA
LATE SATURDAY AND INTO SUNDAY.
WATER VAPOR IMAGERY SHOWS OUR DISTURBANCE OF INTEREST CURRENTLY
DIGGING SOUTHWARD JUST OFF THE WASHINGTON OREGON COAST. GUIDANCE
CONTINUES TO DIG THIS PV ANOMALY ACROSS THE SOUTHWEST..NEAR BAJA
CALIFORNIA BY FRIDAY EVENING. MEANWHILE...THE QUASI-ZONAL FLOW
PATTERN...CURRENTLY IN PLACE ACROSS MOST OF THE CONUS WILL QUICKLY
TRANSITION INTO A SOUTHWESTERLY FLOW PATTERN ALOFT...AS THIS SYSTEM
CONTINUES TO DIG ACROSS THE WEST. THE ASSOCIATED STRONG DOWNSTREAM
HEIGHT RISES WILL ULTIMATELY SET UP AN IMPRESSIVE ~590DM 500 MB HIGH
OFF THE FLORIDA COAST BY EARLY SATURDAY.
THE LATEST GUIDANCE IS NOW BEGINNING TO TREND TOWARDS A BETTER
DEVELOPED SURFACE LOW ACROSS THE MID MISSISSIPPI VALLEY AND
GREAT LAKES REGION...RATHER THAN A MORE ELONGATED SURFACE SYSTEM.
THIS APPEARS TO BE DUE TO THE FACT THAT THE NEGATIVELY TILTED MID
LEVEL IMPULSE MAY NOT ENCOUNTER AS MUCH CONFLUENT FLOW...AS
PREVIOUSLY THOUGHT...AS IT LIFTS NORTHEASTWARD TOWARDS THE MID
MISSISSIPPI VALLEY..THUS NOT SHEARING THE WAVE OUT AS QUICKLY ACROSS
THE AREA. IN ADDITION...LOWER LEVEL PV ANOMALIES...LIKELY ASSOCIATED
WITH CONVECTIVE ACTIVITY TO THE SOUTH...SHOULD HELP TO ONLY DEEPEN
THE LOW. AS SUCH...A STRONGER AND MORE NORTHWEST TRACK APPEARS TO BE
THE WAY TO GO AT THIS TIME...THOUGH THERE IS STILL TIME FOR CHANGES
IN THE TRACK OF THE SYSTEM AS IT GETS BETTER SAMPLED BY THE RAOB
NETWORK.
OVERALL...THIS INCREASES THE LIKELIHOOD OF MORE RAIN ACROSS MOST OF
NORTHERN ILLINOIS AND DECREASES CHANCES OF SIGNIFICANT ICE AND SNOW.
STRONG MOISTURE CONVERGENCE AND FRONTOGENESIS ALONG THE NOSE OF A 60
KT SOUTHERLY LOW LEVEL JET WILL QUICKLY PUMP IN ANOMALOUS AMOUNTS OF
MOISTURE. MOST GUIDANCE IS SUGGESTING PWATS NEAR AND EVEN IN EXCESS
OF AN INCH ARE LIKELY ACROSS MOST OF THE AREA BY SATURDAY EVENING.
THIS IS ABOUT 300% OF NORMAL FOR THIS TIME OF YEAR. THIS SHOULD
SUPPORT A LARGE SWATH OF RAINFALL TO LIFT NORTHWARD ACROSS MY
SOUTHERN COUNTIES DURING THE DAY SATURDAY...POSSIBLY GETTING INTO
NORTHERN ILLINOIS AS EARLY AS SATURDAY AFTERNOON. THE PRECIP COULD
INITIAL BEGIN AS SOME SLEET OR LIGHT SNOW...ESPECIALLY ACROSS
NORTHERN ILLINOIS LATE SATURDAY...BUT CONTINUED WARM ADVECTION
SHOULD WARM TEMPS ENOUGH TO RESULT IN MAINLY RAIN IN THE CHICAGO
AREA FOR SATURDAY NIGHT. THE BIG AREAS OF POSSIBLE CONCERN WILL BE
ACROSS NORTH CENTRAL ILLINOIS...WHERE MARGINAL THERMAL PROFILES
COULD STILL SUPPORT A MIX OF SNOW...SLEET AND EVEN SOME FREEZING
RAIN.
OTHERWISE...THE MAIN STORY WILL BE THE GOOD POTENTIAL FOR
SIGNIFICANT RAINFALL ACROSS THE SOUTHERN HALF OF THE AREA.
INDICATIONS CONTINUE TO POINT TO AT LEAST 2 TO 3 INCH RAINFALL
AMOUNTS ACROSS MY EAST CENTRAL ILLINOIS AND NORTHWESTERN INDIANA
COUNTIES. THIS COMBINED WITH THE 0.5 TO 0.75 INCHES CURRENTLY IN THE
SNOW PACK...AND A FROZEN GROUND...COULD LEAD TO SOME SIGNIFICANT
FLOODING CONCERNS SATURDAY NIGHT INTO SUNDAY.
FINALLY AS THE MID LEVEL WAVE MOVES ACROSS THE AREA AND THE SURFACE
LOW MOVES ACROSS LOWER MICHIGAN ON SUNDAY...A DEFORMATION BAND OF
SNOW IS LIKELY...POSSIBLY HEAVY. HOWEVER...DEPENDING ON THE ULTIMATE
TRACK OF THIS SYSTEM...THE BETTER CHANCES MAY REMAIN PRIMARILY
ACROSS EASTERN IOWA AND NORTHWESTERN AND NORTH CENTRAL ILLINOIS AND
POINTS NORTHEAST. THE PROSPECTS OF A DRY SLOT PUSHING IN ACROSS
NORTHEASTERN ILLINOIS AND NORTHWESTERN INDIANA MAY RESULT IN ONLY
LIGHT PRECIP ON SUNDAY...IF ANY AT ALL. FOR NOW I HAVE CONTINUED
WITH LIKELY POPS ACROSS THE AREA...BUT IF THIS DRY SLOT DOES PUSH
ACROSS THE AREA ON SUNDAY...MUCH OF NORTHEAST AND EAST CENTRAL
ILLINOIS AND NORTHWEST INDIANA MAY NOT SEE MUCH ADDITIONAL PRECIP
SUNDAY.
KJB
LONG TERM...SUNDAY NIGHT THROUGH CHRISTMAS DAY...
SUNDAY NIGHT...
A SHOT OF VERY COLD AIR WILL FOLLOW THE BIG WEEKEND STORM FOR EARLY
NEXT WEEK AS A 1035 TO 1040 MB HIGH BUILDS SOUTH FROM THE NORTHERN
PLAINS. ALL OF THE SYSTEM SNOWS SHOULD BE OFF TO THE EAST SUNDAY
NIGHT...BUT POSITIVE VORTICITY ADVECTION FROM SHORT WAVES ROTATING
AROUND DEEP UPPER TROUGH OVER THE REGION COULD SQUEEZE OUT SOME
LIGHT SNOW OR FLURRIES IN THE ARCTIC AIR MASS. THE 12Z ECMWF IS
MOST BULLISH WITH THIS SCENARIO IN SQUEEZING OUT LIGHT QPF OVER
THE AREA. TEMPERATURES WILL PLUMMET IN STRONG COLD ADVECTION/H85
TEMPS COOLING TO THE MID MINUS TEENS CELSIUS/BUT PERSISTENT NW
WINDS AND CLOUD COVER COULD LIMIT HOW FAR THEY FALL. WITH THE
RAPIDLY FALLING TEMPERATURES SUNDAY NIGHT...ANY REMAINING MOISTURE
ON THE GROUND WILL LIKELY FREEZE QUICKLY.
MONDAY...
ADDED A SLIGHT CHANCE OF FLURRIES ON MONDAY MORNING AS THE DEEP
UPPER TROUGH WILL BE OVERHEAD AND IT MAY NOT BE HARD TO SQUEEZE OUT
DENDRITES DESPITE THE COLD DRY AIRMASS. WILL ALSO HAVE TO WATCH FOR
WIND DIRECTION TRENDS ACROSS LAKE MICHIGAN WITH A FAVORABLE
THERMODYNAMIC SET UP FOR LAKE EFFECT SNOW. HIGH TEMPERATURES
MONDAY AND LOWS MONDAY NIGHT WILL BE COLD EVERYWHERE...BUT HOW
COLD WILL DEPEND ON WHICH AREAS MAINTAIN MOST OF THEIR SNOW COVER
AFTER THE WEEKEND SYSTEM. AT THIS TIME...IT APPEARS THAT THE
NORTHERN CWA WOULD HAVE THE BEST CHANCE AND THE SOUTHEAST CWA THE
LOWEST CHANCE. WITH POTENTIAL FOR SURFACE RIDGE AXIS TO BE OVER
THE AREA...COULD CERTAINLY ENVISION SNOW COVERED AREAS DIPPING TO
AT LEAST A FEW DEGREES BELOW ZERO.
TUESDAY NIGHT AND WEDNESDAY...
AFTER A VERY COLD START TO CHRISTMAS EVE DAY...SOUTHWEST WARM
ADVECTION BEHIND TROUGH DEPARTING TO THE EAST WILL ENABLE AFTERNOON
TEMPERATURES TO RECOVER FAIRLY NICELY. COULD SEE TEMPERATURES BEING
A BIT WARMER THAN CURRENTLY FORECAST IN AREAS WITHOUT SNOWCOVER.
THEN LOOKING OUT TO CHRISTMAS DAY...MEDIUM RANGE GUIDANCE SHOWS A
CLIPPER SYSTEM SCOOTING THROUGH THE UPPER LAKES. THE 12Z ECMWF
INDICATES AN UPPER WAVE IN ASSOCIATION WITH THE COLD FRONT TRAILING
FROM THE CLIPPER. IF THIS WERE TO OCCUR...THERE COULD BE SOME LIGHT
SNOW OR FLURRIES IN THE AIR ON CHRISTMAS DAY...A MINOR CONSOLATION
PRIZE TO EVERYONE WANTING A WHITE CHRISTMAS IN AREAS THAT MAY LOSE
MOST OR ALL OF THEIR SNOWPACK THIS WEEKEND. HAVE MAINTAINED A DRY
FORECAST PER GUIDANCE BLEND INITIALIZATION FOR NOW...BUT ONE CAN
ONLY HOPE.
RC
&&
.HYDROLOGY...309 PM CST
THERE LOOKS TO BE AN INCREASING THREAT OF HEAVY RAINFALL AND
FLOODING THIS WEEKEND. FOR ADDITIONAL DETAILS PLEASE REFER TO THE
FLOOD POTENTIAL OUTLOOK (CHIESFLOT) ISSUED THIS AFTERNOON.
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 06Z...
* LLWS PERSISTS THROUGH 09Z.
* WINDS BCMG EAST IN THE AFTN...ARND 5 KT.
* -DZ IS PSBL IN THE AFTN...WITH -RA EXPECTED IN THE EVENING AND
OVERNIGHT. MVFR TO IFR VSBY IS EXPECTED WITH -DZ AND -RA.
* IFR CIGS ARRIVE BY MID MORNING AND PERSIST THROUGH THE
PERIOD...WITH THE POSSIBILITY OF LIFR CIGS FROM LATE AFTN ON.
JEE
//DISCUSSION...UPDATED 06Z...
HIGH PRESSURE IS OVER THE SOUTHERN ATLANTIC COAST WHILE WEAK LOW
PRESSURE IS OVER NORTHERN WISCONSIN. THE LOW WILL WEAKEN AS IT
SHIFTS EAST TODAY...WHILE A COLD FRONT PUSHES SOUTH DOWN THE LAKE.
IN THE NEAR TERM WINDS WILL REMAIN OUT OF THE SW AT 10 KT OR LESS
AS THE PRESSURE GRADIENT WEAKENS. PUSHED BACK REDUCED VSBYS AND
IFR CIGS AS OBSERVATIONS SUGGEST IT IS STILL TOO DRY FOR EITHER TO
FORM IN THE NEAR TERM.
MOISTURE INCREASES THROUGH THIS MORNING WITH DRIZZLE POSSIBLY
FORMING EARLY THIS AFTN ALONG WITH IFR CIGS. IN ADDITION TO THE
MOISTURE...FORCING INCREASES BY THE AFTN. STILL NOT ENTIRELY
CONFIDENT IN THE START TIME.
THE COLD FRONT SINKS SOUTH WITH VARIABLE WINDS EXPECTED AHEAD OF
IT AND THEN WINDS SETTLE OUT OF THE EAST TO NORTHEAST BEHIND THE
FRONT. SPEEDS SHOULD BE 10 KT OR LESS. GUIDANCE ALSO HINTS AT THE
POSSIBILITY OF LIFR CIGS...SO PUT IN FEW004 FOR NOW.
PRECIP SPREADS FROM WEST TO EAST THIS EVENING AHEAD OF THE NEXT
LOW. MAY SEE A PERIOD OF -FZDZ AT RFD...BUT NOT ENTIRELY
CONFIDENT AS SURFACE TEMPS WILL BE RIGHT AROUND FREEZING. THE REST
OF THE AREA...AND EVENTUALLY AT RFD...RAIN IS EXPECTED. BETWEEN
THE ABUNDANCE OF LOW LEVEL MOISTURE AND RAIN...KEPT IFR VSBY AND
IFR TO LIFR CIGS GOING OVERNIGHT.
JEE
//ORD AND MDW CONFIDENCE...UPDATED 06Z...
* HIGH CONFIDENCE IN FORECAST THROUGH 15Z.
* MEDIUM-HIGH CONFIDENCE IN IFR OR LOWER CIGS OCCURRING...LOW
CONFIDENCE AS TO WHEN THEY ARRIVE AND HOW LOW THEY WILL BE.
* MEDIUM CONFIDENCE IN OCCURRENCE AND START TIME OF -DZ.
* HIGH CONFIDENCE IN RAIN...MEDIUM CONFIDENCE IN 1 SM VSBY IN RA
AS IT COULD BE HIGHER VSBY.
* MEDIUM CONFIDENCE IN BREAK IN PRECIP EARLY FRIDAY MORNING.
* HIGH CONFIDENCE IN WIND FORECAST.
JEE
//OUTLOOK FOR ORD/MDW FOR 12Z FRIDAY-12Z WEDNESDAY...UPDATED 00Z...
FRIDAY...IFR WITH A CHANCE OF LIGHT RAIN IN THE MORNING...POSSIBLY
CHANGING BRIEFLY TO LIGHT SNOW BEFORE ENDING IN THE MORNING WITH
IMPROVEMENT TO MVFR. MODERATELY STRONG NE WIND DURING THE DAY.
SATURDAY...MVFR DETERIORATING TO IFR WITH INCREASING THREAT OF
RA/SN/IP/ZR. RAIN LIKELY IN THE EVENING...TURNING TO SNOW
OVERNIGHT WITH POSSIBLE LIFR. MODERATELY STRONG NE WIND RETURN
OVERNIGHT.
SUNDAY...SNOW LIKELY. IFR OCCASIONALLY LIFR...IMPROVING TO MVFR
IN THE EVENING. MODERATELY STRONG NE WIND GRADUALLY BACKING TO
NW.
MONDAY...VFR. MODERATELY STRONG NW WIND GRADUALLY DIMINISHING.
TUESDAY...VFR.
TRS
&&
.MARINE...
137 PM CST
THE VERY ACTIVE...BUT CHANGEABLE...PATTERN WILL CONTINUE OVER LAKE
MICHIGAN FOR THE NEXT SEVERAL DAYS. LOW PRESSURE MOVING ACROSS THE
UPPER MISSISSIPPI VALLEY AS HIGH PRESSURE SETTLES INTO THE SERN
CONUS IS SETTING UP A STRONG SOUTHERLY GRADIENT OVER LAKE MICHIGAN.
WINDS ARE ALREADY ON THE INCREASE AND EXPECT THAT THE SOUTH WINDS
SHOULD REACH GALE FORCE BY LATE THIS AFTERNOON OR EARLY THIS
EVENING. THE STRONGEST GRADIENT WILL BE OVER THE SOUTHERN PORTIONS
OF THE LAKE AND GALES MAY TOP OUT AT AROUND 40KT...WHEREAS GALES
WILL BE CLOSER TO 35KT OVER THE NORTHERN PORTIONS OF THE LAKE. THE
LOW WILL CROSS THE UPPER GREAT LAKES TONIGHT AND THURSDAY WHILE
DRAGGING A STRONG COLD FRONT DOWN THE LAKE. THE FRONT IS EXPECTED
TO GO STATIONARY OVER THE SOUTHERN TIP OF THE THURSDAY NIGHT...AND
WHILE WINDS OVER MUCH OF THE LAKE NORTH OF A MILWAUKEE TO HOLLAND
LINE SHOULD BECOME NORTHEASTERLY AT 25-30KT...WINDS OVER THE FAR
SOUTHERN TIP OF THE LAKE WILL REMAIN MORE SOUTHERLY AND WEAKER. BY
THURSDAY NIGHT...HIGH PRESSURE BUILDING INTO THE NORTHERN PLAINS
WILL FINALLY HELP THE FRONT PUSH SOUTH OF THE LAKE. BY THURSDAY
MORNING...A LOW PRESSURE SYSTEM IS EXPECTED TO DROP OUT OF THE
CENTRAL ROCKIES AND INTO THE SOUTH HIGH PLAINS AS A WARM FRONT
FORMS...EXTENDING NORTHEAST THROUGH NORTHERN MISSOURI AND INTI
NORTHERN ILLINOIS. WAVES OF LOW PRESSURE WILL RIPPLE ALONG THE WARM
FRONT...AS ANOTHER AREA OF HIGH PRESSURE SLIDES INTO THE NORTHERN
PLAINS. WITH A RIDGE OF HIGH PRESSURE EXTENDING FROM THE CENTRAL
PLAINS THROUGH THE UPPER GREAT LAKES AND INTO QUEBEC...A PERSISTENT
NELY TO ELY FETCH WILL SET UP OVER THE LAKE FROM THURSDAY NIGHT
THOUGH FRIDAY NIGHT. WHILE GALES ARE NOT EXPECTED AT THIS TIME WITH
THE BRISK NELY FLOW...WINDS MAY APPROACH 30KT THURSDAY NIGHT INTO
FRIDAY MORNING. THERE IS STILL SOME UNCERTAINTY AS THE EXACT TRACK
OF THE LOW DEVELOPING OVER THE SOUTH HIGH PLAINS...BUT THE GENERAL
CONSENSUS IS THAT IT SHOULD PASS TO THE SOUTH OF LAKE MICHIGAN
SUNDAY MORNING AND THE PROCEED NORTHEAST INTO SOUTHERN QUEBEC BY
MONDAY MORNING. YET ANOTHER AREA OF STRONG HIGH PRESSURE WILL BUILD
OUT OF CANADA AND INTO THE PLAINS FOLLOWING THE PASSAGE OF THE LOW.
KREIN
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...GALE WARNING...LMZ080-LMZ261-LMZ362-LMZ364-LMZ366-LMZ563-LMZ565-
LMZ567-LMZ669-LMZ671-LMZ673-LMZ675-LMZ777-LMZ779-LMZ868-
LMZ870-LMZ872-LMZ874-LMZ876-LMZ878 UNTIL 4 AM THURSDAY.
SMALL CRAFT ADVISORY...NEARSHORE GARY TO MICHIGAN CITY IN UNTIL 4 AM THURSDAY.
SMALL CRAFT ADVISORY...NEARSHORE WINTHROP HARBOR TO GARY IN UNTIL 2 AM
THURSDAY.
&&
$$
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WWW.YOUTUBE.COM/NWSCHICAGO
Area Forecast Discussion
National Weather Service Lincoln IL
1114 PM CST Wed Dec 18 2013
.DISCUSSION...
ISSUED 825 PM CST Wed Dec 18 2013
Tight pressure gradient over central Illinois this evening has
kept the gusty southerly winds going thru much of the area. Had
a wind gust up to 40 mph in Danville over the past hour with
many areas seeing sustained winds of 20 to 25 mph this evening.
This should help keep temps steady or even slowly rising later
tonight as the winds only slowly decrease in advance of a cold
front still well west of our area. As of 02z, the front was
analyzed over western Iowa and will gradually work its way east
overnight. Surface dew points were gradually increasing to our
south and west this evening, with most of the 40 and 50 degree
dew points still well southwest of area over parts of central
Texas.
As the cold front slips south and east towards eastern Iowa
by morning, our wind speeds will decrease and with the persistent
advection of higher dew point air over the snow covered areas
in central Illinois, we should develop some low level cloud cover
and possibly some fog, especially across our far northwest, which
will be closer to the approaching cold front. A zone update was
sent out earlier in the evening to address the stronger winds
over the forecast area with the remainder of the forecast still
holding, so no additional update will be needed at this time.
Smith
&&
.AVIATION...
ISSUED 1110 PM CST Wed Dec 18 2013
Little change from earlier thinking this evening, the main
challenge will be timing of the IFR/LIFR cigs and vsbys into
the forecast area on Thursday. Tight pressure gradient over
the state this evening resulted in rather gusty south winds.
The surface winds are expected to diminish some during the
early morning hours, however, the latest short term forecasts
suggest the LLWS in the 1500 ft level will continue thru 12z.
A cold front over the northwest half of Iowa will push to the
Mississippi River by dawn Thursday and then slowly edge east
into our area during the day. The persistent southerly winds
will aid in transporting higher moisture northeast over the
colder/snow covered areas of central IL, which will lead to
widespread low cigs and vsbys, especially during the afternoon
and evening. Confidence on the timing of the lower cigs and
vsbys in our area is not that great at this time as most models
have been too aggressive in developing the IFR cigs and vsbys.
However, the HRRR model has been quite consistent in keeping
the low cigs out thru the morning with development taking place
by afternoon from west to east. Will tend to lean more on that
model`s timing at this point.
Surface winds will remain out of the south at 12 to 17 kts into
the early morning hours with a gradual decrease in the sustained
winds by morning. Southerly winds will hold over the area thru
Thursday with speeds of 8 to 13 kts. Forecast soundings indicate
the potential for some light rain or drizzle with the lower cigs
and vsbys Thursday evening.
Smith
&&
.PREV DISCUSSION...
ISSUED 256 PM CST Wed Dec 18 2013
Forecast problem is the complicated precipitation types with the
next frontal system to move into region Friday and produce pcpn
through the weekend.
SHORT TERM...Tonight through Friday night.
Upper air and moisture channel this morning shows main trough off
the west US that will move to the east and affect region by
weekend. Models have become very similar now in the movement of
the cold front into the plains, warming in the low levels ahead of
the front for Thursday and the front slipping into IL Thurs night
through Friday, with some light overrunning pcpn behind the front.
Main pcpn though with be in response to the southwest US upper low
coming out and producing major lift over the front into OH and mid
MS valleys.
LONG TERM...Saturday through Wednesday.
As the system moves out of the southern plains, pcpn develops
Friday night and spreads north into central IL Saturday. Looking
at all the models forecast soundings, have modified pcpn types
toward a little warmer conditions and so tried to push the
freezing rain chances further to the northwest, decreasing the
amount of ice in the central sections, but still with some
possible ice in the northern parts of central IL. Rain Saturday
and overnight will be the main issue with the southeast sections
possibly getting as much as 3 inches storm total. On Sunday, the
deformation should set up northwest of the CWA, with some snow
amounts in the northwest sections before ending.
&&
.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS GOODLAND KS
1155 PM MST WED DEC 18 2013
.UPDATE...
ISSUED AT 748 PM MST WED DEC 18 2013
SEEING A LOT OF VARIABILITY WITH HOURLY TEMPERATURES TONIGHT WITH
A FEW SITES ALREADY DROPPING TO AROUND FREEZING...BUT THEN RISING
AGAIN AS HIGH CLOUDS MOVE OVER. TRIED TO ACCOUNT FOR THIS
VARIABILITY...BUT GIVEN THE DEGREE OF CHANGE GETTING A PERFECT
CURVE WILL BE DIFFICULT. DESPITE THE INITIAL DROP...CURRENT
FORECAST LOOKS ON TRACK WITH ONLY A FEW MINOR CHANGES MADE. LOOKS
LIKE FRONT WILL BEGIN TO IMPACT AREA IN THE MORNING BUT STRONGEST
PUSH OF COLD AIR WILL OCCUR JUST AFTER 18Z.
&&
.SHORT TERM...(THIS AFTERNOON THROUGH THURSDAY)
ISSUED AT 100 PM MST WED DEC 18 2013
LATEST WV IMAGERY AND RAP H5 ANALYSIS INDICATES WESTERLY ZONAL FLOW
IN PLACE ACROSS THE UNITED STATES...WITH TWO SHORTWAVE TROUGHS
UPSTREAM OFF THE WEST COAST. THE FIRST TROUGH IS CENTERED OVER
BRITISH COLUMBIA...WITH THE SECOND JUST WEST OF THE BAJA PENINSULA.
AT THE SURFACE A TROUGH OF LOW PRESSURE EXTENDS FROM EASTERN
COLORADO AND ACROSS SOUTH WEST NEBRASKA. A COLD FRONT IS IN PLACE
ACROSS CENTRAL MONTANA AND NORTH DAKOTA WITH AN ARCTIC HIGH PRESSURE
SYSTEM LURKING TO THE NORTH OF THE FEATURE READY TO MAKE A TREK
SOUTH INTO THE PLAINS.
WITH WESTERLY CROSS MOUNTAIN FLOW AND EMBEDDED UPPER LEVEL ENERGY
CONTINUE TO MOVE EAST I WOULD EXPECT CLOUD COVER TO BEGIN TO
INCREASE ONCE AGAIN TONIGHT...ESPECIALLY AFTER MIDNIGHT AS A TROUGH
BEGINS TO MOVE FROM THE PAC NW AND DEEPEN ACROSS THE GREAT BASIN.
CLOUD COVER COULD HAVE A NEGATIVE IMPACT ON RADIATIONAL COOLING...AND
I WAS NOT CONFIDENT IN HOW LOW WE WILL ACTUALLY DROP BEFORE WINDS
POSSIBLY INCREASE TOWARDS DAYBREAK THURSDAY. I HAVE TRENDED TEMPS UP
A LITTLE.
TEMPERATURE FORECAST THURSDAY IS COMPLICATED BY TIMING OF ARCTIC
FRONT ARRIVAL. NAM/GFS CONTINUE TO SHOW FROPA IN THE 12-18Z TIME
PERIOD...WITH THE LATEST RUNS OF THE ECMWF/GEM SEEM TO FAVOR AN
AFTERNOON FRONTAL PASSAGE. CONTINUITY AND PERSONAL EXPERIENCE WOULD
FAVOR THE QUICKER PASSAGE...HOWEVER WITH ABOUT 6HR OF SPREAD IN
SOLUTIONS THIS COULD HAVE A LARGE IMPACT ON HIGH TEMPS. GOING BY THE
COLDER END OF GUIDANCE NORTHERN HALF OF THE CWA LIKELY WOULDNT MAKE
IT ABOVE FREEZING AND TEMPS WOULD BE FALLING TO THE 20S BY MID
AFTERNOON. WARMER END OF GUIDANCE ALLOWS ENOUGH OF A WINDOW FOR
TEMPS TO RISE TO AT LEAST THE UPPER 40S IF NOT THE LOW 50S ACROSS
THE SOUTH. I NUDGED THE FORECAST TOWARDS THE FASTER
GUIDANCE...HOWEVER CONFIDENCE IS NOT PARTICULARLY HIGH ON HOW THIS
WILL TIME OUT. WE COULD END UP SEEING HIGHS IN THE NORTH OCCURRING
IN THE EARLY MORNING NEAR SUNRISE.
GUIDANCE CONTINUES TO SHOW INCREASING MID LEVEL MOISTURE AND WEAK
FORCING FROM THE NORTHWEST...SO I COULDNT RULE OUT A FEW FLURRIES
BY LATE THURSDAY AFTERNOON. I LEFT MENTION IN PLACE OVER YUMA
COUNTY IN LINE WITH PREVIOUS FORECAST.
.LONG TERM...(SUNDAY THROUGH THURSDAY)
ISSUED AT 1148 PM MST WED DEC 18 2013
NORTHWEST FLOW WILL BE THE MAJOR THEME IN THE LONG TERM PERIOD. A
COUPLE OF SHORTWAVE DISTURBANCES WILL MOVE THROUGH AND BRING BRIEF
COOL DOWNS KEEPING TEMPERATURES NEAR CLIMATOLOGICAL NORMALS. THERE
WILL BE SOME WEAK FORCING WITH EACH WAVE...BUT PRECIPITATION
CHANCES APPEAR SLIM TO NONE WITH ONLY LIMITED LOW LEVEL MOISTURE
AVAILABLE.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z THURSDAY NIGHT)
ISSUED AT 1154 PM MST WED DEC 18 2013
VFR CONDITIONS WITH CLOUDY THROUGH THE TAF PERIOD AT MCK AND GLD.
EXPECT WINDS TO INCREASE AND SHIFT TO THE EAST/NORTHEAST FOLLOWING
THE PASSAGE OF A COLD FRONT AT MCK AND THEN GLD AFTER ABOUT 15Z.
EXPECT CEILINGS TO DROP...BUT REMAIN VFR WITH THE ADVANCE OF THE
MUCH COLDER PUSH BETWEEN 01Z-03Z. WINDS WILL ALSO BECOME GUSTY OUT
OF THE NORTH AT THAT TIME.
&&
.GLD WATCHES/WARNINGS/ADVISORIES...
KS...NONE.
CO...NONE.
NE...NONE.
&&
$$
UPDATE...JRM
SHORT TERM...DR
LONG TERM...024
AVIATION...LOCKHART
AREA FORECAST DISCUSSION
NWS GOODLAND KS
1153 PM MST WED DEC 18 2013
.UPDATE...
ISSUED AT 748 PM MST WED DEC 18 2013
SEEING A LOT OF VARIABILITY WITH HOURLY TEMPERATURES TONIGHT WITH
A FEW SITES ALREADY DROPPING TO AROUND FREEZING...BUT THEN RISING
AGAIN AS HIGH CLOUDS MOVE OVER. TRIED TO ACCOUNT FOR THIS
VARIABILITY...BUT GIVEN THE DEGREE OF CHANGE GETTING A PERFECT
CURVE WILL BE DIFFICULT. DESPITE THE INITIAL DROP...CURRENT
FORECAST LOOKS ON TRACK WITH ONLY A FEW MINOR CHANGES MADE. LOOKS
LIKE FRONT WILL BEGIN TO IMPACT AREA IN THE MORNING BUT STRONGEST
PUSH OF COLD AIR WILL OCCUR JUST AFTER 18Z.
&&
.SHORT TERM...(THIS AFTERNOON THROUGH THURSDAY)
ISSUED AT 100 PM MST WED DEC 18 2013
LATEST WV IMAGERY AND RAP H5 ANALYSIS INDICATES WESTERLY ZONAL FLOW
IN PLACE ACROSS THE UNITED STATES...WITH TWO SHORTWAVE TROUGHS
UPSTREAM OFF THE WEST COAST. THE FIRST TROUGH IS CENTERED OVER
BRITISH COLUMBIA...WITH THE SECOND JUST WEST OF THE BAJA PENINSULA.
AT THE SURFACE A TROUGH OF LOW PRESSURE EXTENDS FROM EASTERN
COLORADO AND ACROSS SOUTH WEST NEBRASKA. A COLD FRONT IS IN PLACE
ACROSS CENTRAL MONTANA AND NORTH DAKOTA WITH AN ARCTIC HIGH PRESSURE
SYSTEM LURKING TO THE NORTH OF THE FEATURE READY TO MAKE A TREK
SOUTH INTO THE PLAINS.
WITH WESTERLY CROSS MOUNTAIN FLOW AND EMBEDDED UPPER LEVEL ENERGY
CONTINUE TO MOVE EAST I WOULD EXPECT CLOUD COVER TO BEGIN TO
INCREASE ONCE AGAIN TONIGHT...ESPECIALLY AFTER MIDNIGHT AS A TROUGH
BEGINS TO MOVE FROM THE PAC NW AND DEEPEN ACROSS THE GREAT BASIN.
CLOUD COVER COULD HAVE A NEGATIVE IMPACT ON RADIATIONAL COOLING...AND
I WAS NOT CONFIDENT IN HOW LOW WE WILL ACTUALLY DROP BEFORE WINDS
POSSIBLY INCREASE TOWARDS DAYBREAK THURSDAY. I HAVE TRENDED TEMPS UP
A LITTLE.
TEMPERATURE FORECAST THURSDAY IS COMPLICATED BY TIMING OF ARCTIC
FRONT ARRIVAL. NAM/GFS CONTINUE TO SHOW FROPA IN THE 12-18Z TIME
PERIOD...WITH THE LATEST RUNS OF THE ECMWF/GEM SEEM TO FAVOR AN
AFTERNOON FRONTAL PASSAGE. CONTINUITY AND PERSONAL EXPERIENCE WOULD
FAVOR THE QUICKER PASSAGE...HOWEVER WITH ABOUT 6HR OF SPREAD IN
SOLUTIONS THIS COULD HAVE A LARGE IMPACT ON HIGH TEMPS. GOING BY THE
COLDER END OF GUIDANCE NORTHERN HALF OF THE CWA LIKELY WOULDNT MAKE
IT ABOVE FREEZING AND TEMPS WOULD BE FALLING TO THE 20S BY MID
AFTERNOON. WARMER END OF GUIDANCE ALLOWS ENOUGH OF A WINDOW FOR
TEMPS TO RISE TO AT LEAST THE UPPER 40S IF NOT THE LOW 50S ACROSS
THE SOUTH. I NUDGED THE FORECAST TOWARDS THE FASTER
GUIDANCE...HOWEVER CONFIDENCE IS NOT PARTICULARLY HIGH ON HOW THIS
WILL TIME OUT. WE COULD END UP SEEING HIGHS IN THE NORTH OCCURRING
IN THE EARLY MORNING NEAR SUNRISE.
GUIDANCE CONTINUES TO SHOW INCREASING MID LEVEL MOISTURE AND WEAK
FORCING FROM THE NORTHWEST...SO I COULDNT RULE OUT A FEW FLURRIES
BY LATE THURSDAY AFTERNOON. I LEFT MENTION IN PLACE OVER YUMA
COUNTY IN LINE WITH PREVIOUS FORECAST.
.LONG TERM...(SUNDAY THROUGH THURSDAY)
ISSUED AT 1148 PM MST WED DEC 18 2013
NORTHWEST FLOW WILL BE THE MAJOR THEME IN THE LONG TERM PERIOD. A
COUPLE OF SHORTWAVE DISTURBANCES WILL MOVE THROUGH AND BRING BRIEF
COOL DOWNS KEEPING TEMPERATURES NEAR CLIMATOLOGICAL NORMALS. THERE
WILL BE SOME WEAK FORCING WITH EACH WAVE...BUT PRECIPITATION
CHANCES APPEAR SLIM TO NONE WITH ONLY LIMITED LOW LEVEL MOISTURE
AVAILABLE.
&&
.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z THURSDAY EVENING)
ISSUED AT 422 PM MST WED DEC 18 2013
VFR CONDITIONS SHOULD LAST THROUGH THE TAF PERIOD. THE ONLY
QUESTIONABLE TIME PERIOD MAY BE LATE IN THE TAF PERIOD TOWARDS 0Z
TOMORROW FOR KMCK. WINDS WILL BE LIGHT AND VARIABLE THIS EVENING AND
OVERNIGHT WITH INCREASING HIGH CLOUDS. A COLD FRONT WILL MOVE
THROUGH THE TERMINALS EARLY TOMORROW...WITH WINDS SHIFTING TO THE
EAST-NORTHEAST AND INCREASING ABOVE 12 KTS BY MID-LATE MORNING FOR
KMCK AND LATE MORNING FOR KGLD. CEILINGS WILL BEGIN TO DECLINE
BEHIND THE FRONT...STAYING WITHIN VFR CRITERIA AS OF RIGHT NOW.
THE GFS BUFKIT SOUNDING INDICATES LOW CLOUD LAYER DEVELOPING AT
KMCK EARLY TOMORROW AFTERNOON...WITH THE NAM BUFKIT SOUNDING
INDICATING THE LOW CLOUD LAYER AFTER 0Z. THEREFORE...COULD
ANTICIPATE THE POSSIBILITY OF LOWER CEILINGS AT KMCK TOMORROW
SLIGHTLY BEFORE OR AFTER 0Z...BUT KEPT VFR CONDITIONS AS OF RIGHT NOW.
&&
.GLD WATCHES/WARNINGS/ADVISORIES...
KS...NONE.
CO...NONE.
NE...NONE.
&&
$$
UPDATE...JRM
SHORT TERM...DR
LONG TERM...024
AVIATION...ALW
AREA FORECAST DISCUSSION
NWS GOODLAND KS
1152 PM MST WED DEC 18 2013
.UPDATE...
ISSUED AT 748 PM MST WED DEC 18 2013
SEEING A LOT OF VARIABILITY WITH HOURLY TEMPERATURES TONIGHT WITH
A FEW SITES ALREADY DROPPING TO AROUND FREEZING...BUT THEN RISING
AGAIN AS HIGH CLOUDS MOVE OVER. TRIED TO ACCOUNT FOR THIS
VARIABILITY...BUT GIVEN THE DEGREE OF CHANGE GETTING A PERFECT
CURVE WILL BE DIFFICULT. DESPITE THE INITIAL DROP...CURRENT
FORECAST LOOKS ON TRACK WITH ONLY A FEW MINOR CHANGES MADE. LOOKS
LIKE FRONT WILL BEGIN TO IMPACT AREA IN THE MORNING BUT STRONGEST
PUSH OF COLD AIR WILL OCCUR JUST AFTER 18Z.
&&
.SHORT TERM...(THIS AFTERNOON THROUGH THURSDAY)
ISSUED AT 100 PM MST WED DEC 18 2013
LATEST WV IMAGERY AND RAP H5 ANALYSIS INDICATES WESTERLY ZONAL FLOW
IN PLACE ACROSS THE UNITED STATES...WITH TWO SHORTWAVE TROUGHS
UPSTREAM OFF THE WEST COAST. THE FIRST TROUGH IS CENTERED OVER
BRITISH COLUMBIA...WITH THE SECOND JUST WEST OF THE BAJA PENINSULA.
AT THE SURFACE A TROUGH OF LOW PRESSURE EXTENDS FROM EASTERN
COLORADO AND ACROSS SOUTH WEST NEBRASKA. A COLD FRONT IS IN PLACE
ACROSS CENTRAL MONTANA AND NORTH DAKOTA WITH AN ARCTIC HIGH PRESSURE
SYSTEM LURKING TO THE NORTH OF THE FEATURE READY TO MAKE A TREK
SOUTH INTO THE PLAINS.
WITH WESTERLY CROSS MOUNTAIN FLOW AND EMBEDDED UPPER LEVEL ENERGY
CONTINUE TO MOVE EAST I WOULD EXPECT CLOUD COVER TO BEGIN TO
INCREASE ONCE AGAIN TONIGHT...ESPECIALLY AFTER MIDNIGHT AS A TROUGH
BEGINS TO MOVE FROM THE PAC NW AND DEEPEN ACROSS THE GREAT BASIN.
CLOUD COVER COULD HAVE A NEGATIVE IMPACT ON RADIATIONAL COOLING...AND
I WAS NOT CONFIDENT IN HOW LOW WE WILL ACTUALLY DROP BEFORE WINDS
POSSIBLY INCREASE TOWARDS DAYBREAK THURSDAY. I HAVE TRENDED TEMPS UP
A LITTLE.
TEMPERATURE FORECAST THURSDAY IS COMPLICATED BY TIMING OF ARCTIC
FRONT ARRIVAL. NAM/GFS CONTINUE TO SHOW FROPA IN THE 12-18Z TIME
PERIOD...WITH THE LATEST RUNS OF THE ECMWF/GEM SEEM TO FAVOR AN
AFTERNOON FRONTAL PASSAGE. CONTINUITY AND PERSONAL EXPERIENCE WOULD
FAVOR THE QUICKER PASSAGE...HOWEVER WITH ABOUT 6HR OF SPREAD IN
SOLUTIONS THIS COULD HAVE A LARGE IMPACT ON HIGH TEMPS. GOING BY THE
COLDER END OF GUIDANCE NORTHERN HALF OF THE CWA LIKELY WOULDNT MAKE
IT ABOVE FREEZING AND TEMPS WOULD BE FALLING TO THE 20S BY MID
AFTERNOON. WARMER END OF GUIDANCE ALLOWS ENOUGH OF A WINDOW FOR
TEMPS TO RISE TO AT LEAST THE UPPER 40S IF NOT THE LOW 50S ACROSS
THE SOUTH. I NUDGED THE FORECAST TOWARDS THE FASTER
GUIDANCE...HOWEVER CONFIDENCE IS NOT PARTICULARLY HIGH ON HOW THIS
WILL TIME OUT. WE COULD END UP SEEING HIGHS IN THE NORTH OCCURRING
IN THE EARLY MORNING NEAR SUNRISE.
GUIDANCE CONTINUES TO SHOW INCREASING MID LEVEL MOISTURE AND WEAK
FORCING FROM THE NORTHWEST...SO I COULDNT RULE OUT A FEW FLURRIES
BY LATE THURSDAY AFTERNOON. I LEFT MENTION IN PLACE OVER YUMA
COUNTY IN LINE WITH PREVIOUS FORECAST.
.LONG TERM...(THURSDAY NIGHT THROUGH WEDNESDAY)
ISSUED AT 234 PM MST WED DEC 18 2013
WESTERLY FLOW WILL CONTINUE THROUGH FRIDAY AHEAD OF A TROUGH MOVING
SOUTHEAST FROM SOUTHERN CALIFORNIA. THE TROUGH WILL MOVE EAST INTO
EASTERN NEW MEXICO SATURDAY. SURFACE HIGH PRESSURE WILL MOVE INTO
THE CENTRAL PLAINS THURSDAY NIGHT AND FRIDAY. A SURFACE TROUGH WILL
MOVE INTO EASTERN COLORADO FRIDAY NIGHT. THIS TROUGH WILL MOVE SOUTH
INTO TEXAS SATURDAY WITH A COLD FRONT FOLLOWING.
THERE WILL BE SOME FLURRIES POSSIBLE THURSDAY NIGHT AS COLDER AIR
FILTERS INTO THE REGION BEHIND THE COLD FRONT. PLAN TO CONTINUE THIS
AREA OF FLURRIES OVER THE NORTHWEST FA WHERE H8-7 LAYER MEAN
MOISTURE IS BEST. OTHERWISE POPS WILL BE NIL THROUGH FRIDAY NIGHT
DUE TO SUBSIDENCE. THE UPPER TROUGH OVER EASTERN NEW MEXICO WILL
BRING A SLIGHT CHANCE OF LIGHT SNOW TO THE FAR SOUTHEAST ZONES
SATURDAY AS DYNAMICS MOVE ACROSS SOUTHWEST AND SOUTH CENTRAL KANSAS.
MIN TEMPERATURES THURSDAY NIGHT WILL FALL INTO THE LOWER TEENS AND
COULD BE COLDER IF SKIES CLEAR. THE COLDEST AIR MOVES AWAY SO THAT
LOW TEMPERATURES FRIDAY NIGHT WILL BE IN THE UPPER TEENS. MAX
TEMPERATURES WILL RANGE FROM 30 TO AROUND 35 FRIDAY AND 35 TO AROUND
40 SATURDAY.
IN THE EXTENDED...(SATURDAY NIGHT THROUGH WEDNESDAY)...
SOME LIGHT SNOW WILL BE POSSIBLE SATURDAY NIGHT AS THE ABOVE
MENTIONED TROUGH MOVES EAST ACROSS THE CENTRAL/SOUTHERN PLAINS.
SLIGHT CHANCE POPS WILL BE OVER THE EXTREME SOUTHEAST FA WHERE
MOISTURE IS BEST. UPPER FLOW WILL BECOME NORTHWEST SUNDAY AND CONTINUE
THROUGH WEDNESDAY. SUBSIDENCE DURING THIS TIME WILL BRING DRY
CONDITIONS.
MIN TEMPERATURES WILL RANGE FROM THE TEENS SATURDAY THROUGH SUNDAY
NIGHTS WARMING TO THE LOWER 20S MONDAY THROUGH WEDNESDAY NIGHTS.
MAX TEMPERATURES SUNDAY WILL BE IN THE LOWER 30S. SOME WARMING INTO
THE 40S WILL OCCUR MONDAY THROUGH WEDNESDAY.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z THURSDAY NIGHT)
ISSUED AT 1149 PM MST WED DEC 18 2013
VFR CONDITIONS WITH CLOUDY THROUGH THE TAF PERIOD AT MCK AND GLD.
EXPECT WINDS TO INCREASE AND SHIFT TO THE EAST/NORTHEAST FOLLOWING
THE PASSAGE OF A COLD FRONT AT MCK AND THEN GLD AFTER ABOUT 15Z.
EXPECT CEILINGS TO DROP...BUT REMAIN VFR WITH THE ADVANCE OF THE
MUCH COLDER PUSH BETWEEN 01Z-03Z. WINDS WILL ALSO BECOME GUSTY OUT
OF THE NORTH AT THAT TIME.
&&
.GLD WATCHES/WARNINGS/ADVISORIES...
KS...NONE.
CO...NONE.
NE...NONE.
&&
$$
UPDATE...JRM
SHORT TERM...DR
LONG TERM...FS
AVIATION...LOCKHART
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
453 AM EST THU DEC 19 2013
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 452 AM EST THU DEC 19 2013
A 1005MB LOW PRESSURE OVER EASTERN LAKE SUPERIOR CONTINUES TO
QUICKLY SLIDE EAST THIS MORNING...AS AN ASSOCIATED 925/850MB TROUGH
EXITS THE UPPER GREAT LAKES REGION. THIS QUICK DEPARTURE HAS LED TO
WINDS TURNING TO THE NORTHWEST OVER THE WESTERN LAKE AND AN AREA OF
MVFR CLOUDS (PICKED UP WELL IN THE RH FIELDS OF THE RAP ANALYSIS)
DROPPING SOUTHEAST ACROSS WESTERN AND NORTH CENTRAL UPPER MICHIGAN.
CEILINGS HAVE BEEN LOWERING FAIRLY STEADILY AT KCMX OVER THE LAST
COUPLE OF HOURS AND WITH THE RAP INDICATING 925MB TEMPS FALLING TO
-10C OVER WESTERN LAKE SUPERIOR...HAVE BEEN SEEING INDICATIONS ON
SATELLITE THAT LAKE EFFECT CLOUDS HAVE BEEN DEVELOPING. HAVEN/T
SEEN ANY PRECIPITATION NOTED AT CMX OR ON WEBCAMS OVER THE
KEWEENAW...BUT WOULD EXPECT LIGHT SNOW OR FREEZING DRIZZLE TO START
SHORTLY.
FOR TODAY...WITH THE LOW SLIDING EAST EARLY THIS MORNING AND THE
MAIN SHORTWAVE TO THE NORTHWEST OF LAKE SUPERIOR JUST BRUSHING THE
NORTHERN PART OF THE LAKE...THERE APPEARS TO BE LITTLE SYNOPTIC
FORCING ACROSS THE AREA FOR MUCH OF THE DAY. OTHER THAN THE
POTENTIAL FOR A BRIEF STRONGER SHOWERS MOVING ACROSS EASTERN LAKE
SUPERIOR WITH THE FRONT AND WIND SHIFT TO THE NORTHWEST.
OTHERWISE...THE COLDER AIR DROPPING SOUTHEAST ACROSS LAKE SUPERIOR
(925MB TEMPS FALLING TO -13C BY 00Z FRIDAY) WILL LEAD TO AN INCREASE
IN LIGHT LAKE EFFECT PRECIPITATION THIS MORNING. WITH A HIGH
PRESSURE RIDGE LOCATED JUST TO THE NORTH OF LAKE SUPERIOR TODAY
WILL LEAD TO WINDS VEERING TO THE NORTH-NORTHEAST THROUGH THE DAY.
THIS ANTI-CYCLONIC FLOW ACROSS THE LAKE WON/T BE TOO FAVORABLE FOR
LAKE EFFECT...WHICH WILL COMBINE WITH THE STRONG POCKET OF DRY
AIR ABOVE 850MB (INVERSION HEIGHTS AROUND 4KFT) ASSOCIATED WITH THE
HIGH TO KEEP ANY PRECIPITATION LIGHT. THERE IS SOME CONCERN ON SOME
FREEZING DRIZZLE MIXING WITH THE SNOW FOR THE FIRST PART OF THE
MORNING NEAR LAKE SUPERIOR AND HAVE TRIED TO FOLLOW THE TIMING OF
THE 925MB AROUND -9/-10C TO MARK THE TRANSITION TO ALL SNOW THIS
MORNING. AS FOR AMOUNTS...THINK A DUSTING TO AN INCH SEEMS
REASONABLE...WITH THE MOST IN THE FAVORED NORTH-NORTHEAST UPSLOPE
LOCATIONS OF NORTH CENTRAL UPPER MICHIGAN.
FOR TONIGHT...A QUICK MOVING DISTURBANCE WILL MOVE ACROSS UPPER
MICHIGAN IN THE WESTERLY FLOW ALOFT. IN ADDITIONS TO THE
SHORTWAVE...THE UPPER GREAT LAKES REGION WILL BE UNDER THE
FAVORABLE RIGHT REAR OF A 160KT UPPER JET AND PROVIDE DECENT
SUPPORT ALOFT FOR A SWATH OF SNOW TO MOVE ACROSS THE CWA. AT THE
SURFACE...A WEAK INVERTED TROUGH DOES LOOK TO DEVELOP OVER CENTRAL
UPPER MICHIGAN...WITH WILL HELP KEEP THE LOW LEVEL (950-900MB) FLOW
FOCUSED OVER NORTH CENTRAL UPPER MICHIGAN TO PROVIDE LAKE
ENHANCEMENT. MODELS HAVE BEEN FAIRLY CONSISTENT ON THE SWATH OF
SNOW/QPF MOVING EAST ACROSS THE CWA AROUND MID EVENING AND THEN
QUICKLY DEPARTION ABOUT HALFWAY THROUGH THE OVERNIGHT HOURS.
A GENERAL CONSENSUS IS FOR 0.1-0.15IN OF QPF MOVING ACROSS
CENTRAL/SOUTHERN UPPER MICHIGAN TONIGHT (ONLY 0.05-0.10 OVER THE
KEWEENAW) AND HAVE FOLLOWED THAT FOR THE SYNOPTIC QPF. ONE ITEM TO
NOTE IS THAT THAT DRY POCKET OF AIR BETWEEN 850-700MB WILL NEED TO
BE OVERCOME BEFORE THE SNOW CAN START. FORTUNATELY...THE FLOW IN
THAT LAYER IS FAIRLY LIGHT AND SHOULD ALLOW IT TO QUICKLY MOISTEN.
THEN...WITH THAT FAVORABLE NORTHEAST UPSLOPE AND LAKE ENHANCED
FLOW...ADJUSTED VALUES UP OVER THE HIGHER TERRAIN OF THE NORTH
CENTRAL U.P. FROM THE HURON MOUNTAINS THROUGH NEGAUNEE/GWINN. THE
TRICKY PART IN THE FORECAST COMES FROM PINNING DOWN SNOW RATIOS.
WITH MUCH OF THE BROAD MID LEVEL FGEN FOCUSED WITHIN THE
DGZ...WOULD EXPECT THERE TO BE A 3-4HR PERIOD OF SNOW RATIOS AROUND
20-1 BEFORE A DOWNWARD TREND ONCE THE BETTER FORCING DEPARTS. COBB
OUTPUT AWAY FROM THE LAKE ENHANCEMENT SUPPORTS THAT IDEA AND WITH
THAT DGZ LAYER BEING FAIRLY ISOTHERMAL...HAVE CONTINUED THOSE
RATIOS IN THE FORECAST. IN THE LAKE ENHANCEMENT AREA...THERE ARE
HINTS OF BETTER FORCING BELOW THE DGZ THAT COULD LEAD TO SLIGHTLY
LOWER RATIOS...BUT WONDERING IF THAT MAY BE A TOUCH TOO LOW AS IT
BEING ABOUT 1KFT HIGHER IT WOULD BE IN THE DGZ. THUS...OPTED TO
KEEP THE HIGHER RATIOS IN THE LAKE/TERRAIN ENHANCED AREAS TOO. THIS
LEADS TO A WIDESPREAD 1-3 INCH SNOWFALL FOR MUCH OF UPPER
MICHIGAN...WITH SOME LOCALLY HIGHER AMOUNTS IN THE NORTH CENTRAL.
DEBATED AN ADVISORY FOR MARQUETTE COUNTY FOR AN AVERAGE MORE LIKE
2-4INCHES...BUT OPTED TO DO AN SPS FOR THE ENTIRE CWA INSTEAD.
THERE WERE 2 MAIN REASONS FOR NOT GOING WITH AN ADVISORY.
ONE...SINCE THE MAIN SNOW WILL LIKELY FALL BETWEEN 10PM AND
3AM...THE IMPACTS ON THE POPULATION WILL BE LOWER AND THERE SHOULD
STILL BE ENOUGH TIME TO TREAT THE ROADS BEFORE THE MORNING COMMUTE.
THE SECOND IS A COMBINATION ON UNCERTAINTY WITH SNOW RATIOS AND QPF
AMOUNTS...WHICH BEING OFF BY A COUPLE HUNDREDTHS AT 20 TO 1 COULD
QUICKLY LOWER AMOUNTS. GOING FORECAST WAS FAIRLY SIMILAR TO THE 00Z
NAM AND LOCAL WRF-ARW RUNS...BUT THE 06Z NAM THAT JUST ARRIVED HAS
DROPPED QPF AMOUNTS IN THE ENHANCED AREAS BY 0.07IN. THUS...FELT
HOLDING OFF ON A BORDERLINE ADVISORY WAS WARRANTED AND WILL PASS
CONCERNS TO DAYSHIFT.
.LONG TERM...(FRIDAY THROUGH WEDNESDAY)
ISSUED AT 452 AM EST THU DEC 19 2013
ANY REMAINING MOISTURE AND LIFT RAPIDLY MOVES SOUTH AND EAST ON
FRIDAY MORNING AS A WEAK RIDGE AXIS BUILDS ACROSS LAKE SUPERIOR.
THIS SHOULD ALLOW ANY SNOW SHOWERS OFF THE LAKE TO END QUICKLY IN
THE MORNING. THERE IS A HINT OF LINGERING DEEP MOISTURE ACROSS FAR
SOUTHERN UPPER MI FRI IN THE DEFORMATION ZONE...WITH THE NAM AND
ECMWF SHOWING WEAK MID-LEVEL Q-VECTOR CONVERGENCE THROUGH THE DAY.
HOWEVER...WITH LACK OF SIGNIFICANT LOW LEVEL LIFT AND FAIRLY STRONG
CONFLUENCE ALOFT...WILL LIMIT ANY POPS TO JUST SLIGHT CHANCE ON
FRIDAY ACROSS THE FAR SOUTH.
ON FRIDAY NIGHT INTO SATURDAY...ANOTHER WEAK UPPER TROUGH ROTATES
THROUGH THE AREA. WITH REMAINING MOISTURE ACROSS THE FAR SOUTH FRI
NIGHT...WILL MAINTAIN LOW CHANCE POPS MAINLY IN MENOMINEE COUNTY BUT
AGAIN THE LIFT IS MINIMAL AT BEST. THE NAM SEEMS TO BE AN OUTLIER IN
DEVELOPING A WEAK AREA OF LOW PRESSURE ALONG THE FRONT OVER LAKE
SUPERIOR AND KEEPING IT NEARLY STATIONARY THROUGH SATURDAY BEFORE
MERGING WITH THE DEVELOPING LOW OVER THE SOUTHERN PLAINS SATURDAY
NIGHT. IN FACT...THE NAM ACTUALLY SHOWS ON LAKE MICHIGAN LAKE EFFECT
DEVELOPING IN SCHOOLCRAFT AND DELTA COUNTIES SATURDAY DUE TO THE
SOUTHERLY FLOW AHEAD OF THE LOW. MEANWHILE...THE ECMWF AND THE GFS
SUGGEST A WEAK OPEN WAVE AT BEST WITH MUCH LESS MOISTURE AND LITTLE
IF ANY QPF ON SATURDAY. GIVEN THE WEAK DYNAMICS AT BEST AND THAT THE
NAM IS THE OUTLIER...WILL GENERALLY FOLLOW THE ECMWF SOLUTION AND
KEEP LIMIT ANY POPS TO SLIGHT CHANCE FOR SATURDAY.
FOR THE SOUTHERN STREAM SYSTEM SAT NIGHT INTO SUNDAY NIGHT MOVING
THROUGH THE SOUTHERN GREAT LAKES...THE 18/12Z RUNS STARTED TO TREND
NORTH AND WEST WITH THE LOW. THE 19/00Z RUNS HAVE GENERALLY
CONTINUED THIS TREND WITH THE 19/00Z ECMWF SHIFTING EVEN FURTHER
NORTH AND WEST. WITH THE SYSTEM CLOSING OFF OVER THE SOUTHWESTERN
STATES...WOULD EXPECT THAT THE SYSTEM OVERALL WILL EJECT OUT INTO
THE PLAINS A LITTLE SLOWER THAN THE MODELS SUGGEST. THIS WOULD ALLOW
THE NORTHERN STREAM ENERGY TO POTENTIALLY PHASE WITH THE SOUTHERN
STREAM ENERGY FURTHER NORTH AND WEST...CAUSING THE LOW TO ALSO TRACK
A LITTLE FURTHER NORTH/WEST. AS SUCH...HAVE OPTED TO BRING LIKELY
POPS ACROSS THE ENTIRE EAST HALF OF UPPER MICHIGAN ON SUNDAY/SUNDAY
NIGHT AND RAISE POPS TO NEAR CATEGORICAL IN NORTH CENTRAL UPPER MI.
THIS TYPE OF TRACK WOULD ALLOW FOR A SETUP FOR DECENT LAKE
ENHANCEMENT IN THOSE AREAS FAVORED BY NORTHERLY WINDS WITH PLENTY
OFF DEEP MOISTURE AND AT LEAST SOME SYNOPTIC LIFT IN THE DEFORMATION
ZONE. DO NOT WANT TO TOTALLY BUY OFF ON THE LATEST ECMWF YET AS IT
IS STILL BY FAR THE FURTHEST N AND W...BUT THERE CERTAINLY EXISTS A
POSSIBILITY OF PLOWABLE SNOWFALL FOR MUCH OF THE EASTERN HALF /OR
PERHAPS THE ENTIRE CWFA/ SUNDAY...AND PERHAPS A SIGNIFICANT SNOW FOR
THE FAVORABLE LAKE ENHANCED AREAS. BOTTOM LINE THOUGH...THERE IS
STILL A GREAT AMOUNT OF UNCERTAINTY SO STAY TUNED...
OTHERWISE...BEHIND THIS SYSTEM THE WEATHER QUIETS DOWN WITH A BROAD
LONG WAVE TROUGH SETTLING ACROSS NORTH AMERICA. EXPECT SOME LAKE
EFFECT MONDAY AS THE MAIN SHORT WAVE TROUGH PASSES THROUGH WITH
LINGERING MOISTURE AND 850MB TEMPS AROUND -20C. HOWEVER...THE SFC
RIDGE QUICKLY BUILDS IN BY TUE MORNING WHICH SHOULD END ANY LES.
COULD BE QUITE A COLD MORNING ON CHRISTMAS EVE MORNING WITH THE
RIDGE OVERHEAD AND CLEARING SKIES. WILL GO WITH TEMPS WELL BELOW
ZERO FOR MOST INTERIOR LOCATIONS. MAY BE ONE OF THOSE -20F MORNINGS
IN THE NORMALLY COLDER SPOTS IF IT STAYS CLEAR AND CALM. SOME LIGHT
SNOW IS POSSIBLE LATER ON CHRISTMAS EVE INTO CHRISTMAS DAY AS THE
FRONTAL SYSTEM MOVES INTO THE AREA ASSOCIATED WITH A FAIRLY POTENT
LOOKING SHORT WAVE TROUGH...BUT DETAILS ARE TOUGH TO PIN DOWN. TEMPS
IN THE EXTENDED STILL LOOK BELOW NORMAL.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z THURSDAY NIGHT)
ISSUED AT 1228 AM EST THU DEC 19 2013
OVERNIGHT...EXPECT MVFR CLOUDS TO DEVELOP AT ALL THE TAF SITES AS
MOISTURE MOVES IN JUST AHEAD OF LOW NOW MOVING INTO WRN LAKE
SUPERIOR. MAY EVEN SEE SOME LGT SNOW OR FREEZING DRIZZLE AT CMX OR
IWD LATE TONIGHT TOWARD DAYBREAK ON THURSDAY. THERE IS A BETTER
CHANCE FOR SNOW SHOWERS...STAYING MAINLY IN THE MVFR FLIGHT
CATEGORY...ON THURSDAY AT ALL THE TAF SITES AS COLDER AIR MOVING IN
BEHIND THE LOW PRESSURE SYSTEM RESULTS IN SOME LIGHT LAKE EFFECT
SNOW SHOWERS. SLIGHT IMPROVEMENT IN VSBY/CIGS CAN BE EXPECTED MAINLY
AT KIWD AND KCMX THIS AFTERNOON AS WINDS VEER FROM N TO MORE
DOWNSLOPE NE DIRECTION...BUT STILL EXPECT MVFR CONDITIONS. SYSTEM
SNOW WILL MOVE BACK IN THU EVENING LOWERING VBSYS BACK DOWN NEAR 3
SM.
&&
.MARINE...(FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 452 AM EST THU DEC 19 2013
A LOW DEPARTING EASTERN LAKE SUPERIOR THIS MORNING HAS LED TO AN
INCREASE IN NORTHWEST TO NORTHERLY WINDS ACROSS WESTERN LAKE
SUPERIOR EARLY THIS MORNING AND IT SHOULD SPREAD EAST ACROSS THE
REST OF THE LAKE THROUGH THE MORNING HOURS. ALTHOUGH THERE MAY BE A
FEW GUSTS TO THE 30KT RANGE THIS MORNING...WOULD EXPECT THEM TO
MAINLY BE AROUND 25KTS. A HIGH PRESSURE RIDGE BUILDING OVER
SOUTHERN ONTARIO THIS AFTERNOON WILL WEAKEN THE WINDS THROUGH THE
AFTERNOON AND NIGHT (TO BELOW 20KTS) AS A WEAK LOW TRACKS THROUGH
SOUTHERN LOWER MICHIGAN. THIS HIGH PRESSURE RIDGE WILL CROSS THE
UPPER GREAT LAKES ON FRIDAY AND FRIDAY NIGHT AND LEAD TO CONTINUED
WINDS BELOW 20KTS THROUGH THE FIRST HALF OF THE WEEKEND. A STRONGER
LOW EXITING THE SOUTHERN PLAINS ON SATURDAY AFTERNOON WILL MOVE
THROUGH SOUTHEAST LOWER MICHIGAN ON SUNDAY AND WILL INCREASE
NORTHERLY WINDS ACROSS THE LAKE. AT THIS TIME...EXPECT WINDS TO BE
AROUND 30KTS WITH A FEW GALE FORCE GUSTS TO 35KTS BEFORE DIMINISHING
SUNDAY NIGHT INTO MONDAY.
FINALLY...FREEZING SPRAY WILL BE POSSIBLE DURING THE TIMES OF
STRONGER WINDS...LARGELY TODAY AND LATE SATURDAY NIGHT INTO SUNDAY
NIGHT.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
NONE.
LAKE MICHIGAN...
NONE.
&&
$$
SHORT TERM...SRF
LONG TERM...MRD
AVIATION...VOSS
MARINE...SRF
AREA FORECAST DISCUSSION
NWS DULUTH MN
346 AM CST THU DEC 19 2013
.SYNOPSIS...
ISSUED AT 345 AM CST THU DEC 19 2013
THE STRONG COLD FRONT THAT MOVED THROUGH THE AREA THIS AFTERNOON HAS
PUSHED WELL SOUTH OF THE FORECAST AREA AS OF 3AM. THE SURFACE LOW IS
NOW OVER EASTERN LAKE SUPERIOR...WITH THE FRONT DRAPED ACROSS
WISCONSIN AND IOWA...SOUTHWEST TO A DEVELOPING SURFACE LOW OVER
SOUTHEAST COLORADO. PRESSURE RISES OVER NORTHERN MINNESOTA HAVE
PRODUCED NORTHWEST WINDS OF 5 TO 15KTS OVER THE AREA. TEMPERATURES
FROM ZERO TO 5 ABOVE HAVE COMBINED WITH WINDS TO PRODUCE WIND CHILL
VALUES APPROACHING 20 BELOW.
&&
.SHORT TERM...(TODAY...TONIGHT AND FRIDAY)
ISSUED AT 345 AM CST THU DEC 19 2013
MAIN CONCERN THE NEXT 36 HOURS TO BE ON THE SNOW EXPECTED TO MOVE
ACROSS THE SOUTHERN PORTIONS OF THE FORECAST AREA THURSDAY NIGHT.
TODAY...THE COLD FRONT WILL REMAIN DRAPED WELL SOUTH OF THE AREA
WITH A COLD AIRMASS OVER THE REGION. SURFACE WINDS WILL SLOWLY TURN
TO THE NORTH...AND EVENTUALLY NORTH-NORTHEAST BY THE END OF THE
DAY. LAKE EFFECT SNOW SHOWERS ARE EXPECTED TO DEVELOP ALONG THE
SOUTH LAKE SHORE BY MID TO LATE MORNING...WITH SOME LIGHT
ACCUMULATIONS EXPECTED DURING THE DAY. EARLY THIS MORNING...COLD
TEMPERATURES IN THE SINGLE DIGITS AND WINDS HAVE BEEN STRONG ENOUGH
TO PRODUCE SOME RATHER CHILLY WIND CHILL VALUES...BUT ONLY JUST
APPROACHING ADVISORY CRITERIA. THUS...HAVE CANCELLED THE WIND CHILL
ADVISORY WE HAD OUT.
THE STORM WE HAVE BEEN WATCHING FOR SOME TIME WILL SLOWLY MOVE OUT
ACROSS THE PLAINS TODAY AND ACROSS THE MIDWEST TONIGHT. AN UPPER
LEVEL SHORTWAVE WILL MOVE ACROSS THE US/CANADIAN BORDER...AND THE
SURFACE LOW OVER SOUTHEAST COLORADO THIS MORNING WILL RIPPLE
NORTHEAST ALONG THE SURFACE BOUNDARY...MOVING ACROSS MISSOURI AND
ILLINOIS TONIGHT. A BAND OF STRONG FRONTOGENESIS...WARM AIR
ADVECTION ISENTROPIC LIFT WILL MOVE ACROSS MINNESOTA AND WISCONSIN
TONIGHT. LIGHT SNOW IS EXPECTED TO MOVE INTO THE SOUTHERN PORTIONS
OF THE FORECAST AREA LATE THIS AFTERNOON...AND THEN AFFECT THE
SOUTHERN THIRD OF THE FORECAST AREA TONIGHT WITH LIGHT SNOW. THE
BEST LIFT MOVES ACROSS THE AREA BETWEEN 00Z AND 06Z TONIGHT. QPF
VALUES ARE THE MAIN LIMITING FACTOR...WITH GENERALLY A TENTH OF AN
INCH OR LESS EXPECTED ALONG THE SOUTHERN PORTIONS OF THE FORECAST
AREA. WITH SNOW WATER RATIOS UP OVER 20 TO 1 IN THIS COLD
AIRMASS...WE ARE LOOKING AT A 1 TO 3 INCH SNOWFALL EVENT THIS
EVENING.
SNOW TO MOVE OUT OF THE AREA QUICKLY THURSDAY NIGHT...AND ONLY
EXPECT SOME LIGHT SNOW OVER NORTHWEST WISCONSIN FRIDAY MORNING AS
THE SURFACE RIDGE BUILDS INTO THE AREA. TEMPERATURES TO REMAIN
CHILLY WITH HIGHS RANGING FROM THE SINGLE DIGITS NORTH...TO TEENS
SOUTH.
.LONG TERM...(FRIDAY NIGHT THROUGH WEDNESDAY)
ISSUED AT 345 AM CST THU DEC 19 2013
ACTIVE CYCLONIC FLOW PATTERN CONTINUES ALOFT WITH COMPLEX SFC
FEATURES EARLY IN THE EXTENDED PERIOD PROVIDING LOW SLGT CHC POPS
FRI NIGHT AND THROUGH THE DAY SATURDAY. TWO WEAK INVERTED SFC
TROUGHS...ONE FROM THE NORTH AND ONE FROM THE SOUTH...WILL INTERACT
WITH EACH OTHER DURING THIS TIME AND MAINLY ACT TO PRODUCE MOSTLY
CLOUDY SKIES...BUT ALSO HAVE THE POTENTIAL TO PRODUCE LIGHT SNOW
SHOWERS/FLURRIES. A POTENT LOW PRESSURE SYSTEM WILL LIFT FROM THE
SRN OHIO VALLEY INTO THE NE LATE SAT THROUGH SUN EVENING. THIS
SYSTEM WILL STAY MOSTLY TO THE EAST OF THE NORTHLAND...BUT THE FAR
NRN EXTENT OF THE PRECIP SHIELD COULD BRUSH PARTS OF NRN/CENTRAL WI
ON SUNDAY. THE MAIN IMPACT WITH THIS SYSTEM WILL BE THE DEVELOPMENT
OF AN EAST/NE WIND ACROSS WRN LAKE SUPERIOR. THE COMBINATION OF A
LONG FETCH AND A COOL AIR MASS ALOFT WILL PRODUCE LIGHT LES FROM THE
NORTH SHORE SOUTH INTO THE HEAD OF LAKE SUPERIOR. THE WINDOW OF
OPPORTUNITY WILL BE RELATIVELY NARROW FOR THE NORTH SHORE...SO AMTS
WILL BE LIGHT. A STRONGER PUSH OF COLDER AIR ARRIVES FROM THE NW
WITH AN INCOMING S/W SUN NIGHT. THIS WILL ACT TO ENHANCE THE LES
POTENTIAL...MAINLY ALONG THE SOUTH SHORE AS WINDS BACK TO THE N/NW
INTO EARLY MONDAY. THE FAVORED AREAS OF THE SOUTH SHORE WILL LIKELY
SEE THE MOST SNOW...BUT AMTS WILL STILL REMAIN RELATIVELY LIGHT AS
DRIER AIR MOVES IN QUICKLY ON MONDAY. HIGH PRESSURE BUILDS IN ON
MONDAY BEFORE THE NEXT CLIPPER SYSTEM DROPS IN FROM THE NW TUE AND
WED WITH ADDITIONAL CHANCES FOR SNOW SHOWERS.
TEMPERATURES WILL START OUT RELATIVELY MILD EARLY IN THE WEEKEND
WITH HIGHS IN THE SINGLE DIGITS AND TEENS ABOVE ZERO...AND OVERNIGHT
LOWS IN THE SINGLE DIGITS BELOW ZERO. HOWEVER...LATE SUNDAY A STRONG
BLAST OF ARCTIC AIR ARRIVES ONCE AGAIN AND DROPS TEMPERATURES INTO
THE TEENS AND 20S BELOW ZERO MONDAY MORNING...WITH HIGHS ON MONDAY
ONLY REACHING INTO TO AROUND ZERO. ANOTHER CHILLY NIGHT MON NIGHT
WITH LOWS IN THE SINGLE DIGITS AND TEENS BLO ZERO BEFORE A SLIGHT
WARM UP ON TUE AND WED INTO THE TEENS ABV ZERO FOR HIGHS AND SINGLE
DIGITS ABV ZERO FOR LOWS. ANOTHER COLD BLAST IS POSSIBLE BY LATE IN
THE WEEK.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z THURSDAY NIGHT)
ISSUED AT 1133 PM CST WED DEC 18 2013
THE COLD FRONT HAS PASSED THROUGH MUCH OF THE NORTHLAND THIS
EVENING...WITH AN AREA OF MVFR CEILINGS OCCURRING OVER PORTIONS OF
WESTERN/NORTHERN MINNESOTA. WE INCREASED THE COVERAGE/TIMING OF
MVFR CEILINGS BASED ON LATEST SATELLITE AND OBSERVATIONS. THERE
MAY BE SOME FLURRIES OR A BRIEF SNOW SHOWER THAT OCCURS...BUT
OBSERVATIONS AND RADAR SHOW LIMITED COVERAGE THOUGH. THE RUC AND
SATELLITE SUGGEST THESE LOWER CEILINGS WILL DISSIPATE OVERNIGHT OR
EARLY THURSDAY MORNING. NORTH-NORTHEAST WINDS OVER LAKE SUPERIOR
THURSDAY SHOULD CAUSE LAKE CLOUDS TO DEVELOP AND AFFECT KHYR WITH
MVFR CEILINGS.
A WEAK WAVE WILL RIDE ALONG A BAROCLINIC ZONE THURSDAY
NIGHT...SPREADING LIGHT SNOW TO AREAS ALONG AND SOUTH OF HIGHWAY
2. MVFR/IFR CONDITIONS WILL OCCUR THROUGH THE EARLY MORNING HOURS
AS THE AREA OF SNOW PASSES THROUGH.
&&
.PRELIMINARY POINT TEMPS/POPS...
DLH 11 -4 10 0 / 20 50 0 10
INL -1 -18 6 -5 / 0 20 0 10
BRD 8 -7 8 -3 / 30 70 0 10
HYR 18 3 14 4 / 40 100 10 20
ASX 19 8 15 5 / 60 90 20 20
&&
.DLH WATCHES/WARNINGS/ADVISORIES...
MN...NONE.
WI...NONE.
LS...SMALL CRAFT ADVISORY UNTIL 10 PM CST THIS EVENING FOR LSZ121-
146>148.
&&
$$
SYNOPSIS...LE
SHORT TERM...LE
LONG TERM...BJT
AVIATION...MELDE
AREA FORECAST DISCUSSION
NWS DULUTH MN
1133 PM CST WED DEC 18 2013
.UPDATE...
ISSUED AT 954 PM CST WED DEC 18 2013
A COLD FRONT WAS MOVING THROUGH OUR MINNESOTA ZONES THIS
EVENING...AND WE`VE MADE SOME ADJUSTMENTS TO SHORT TERM GRIDS...AS
WELL AS TO THURSDAY NIGHT POPS/SNOW GRIDS.
WE`VE HAD TO ADJUST TEMPS QUITE A BIT THIS EVENING AS CLOUDS HAVE
NOT BEEN VERY WIDESPREAD ALLOWING TEMPS TO DROP IN LIGHT WINDS
JUST AHEAD OF THE FRONTAL BOUNDARY. THE TEMP CURVE WILL BE A
CHALLENGE TONIGHT...AS WE EXPECT TEMPS TO START TO RISE FOR A TIME
THIS EVENING/EARLY MORNING WHERE THEY HAD DROPPED SHARPLY EARLIER
THIS EVENING. THIS IS DUE TO THICKENING CLOUDS AND INCREASING WINDS.
TEMPS WILL THEN DROP AGAIN LATE TONIGHT WITH STRONG CAA BEHIND THE
FRONT. SNOW SHOWERS WITH THE FRONT HAVE BEEN SPARSE...BUT THERE
ARE A FEW LIGHT ECHOES OUT THERE...SO WE MAINTAINED THE SMALL POPS
FOR MOST AREAS.
LATEST NAM HAS SHIFTED ITS PRECIP AREA A BIT FURTHER NORTH WITH
THE THE FGEN AREA THURSDAY NIGHT...AND GIVEN CONTINUITY AMONG THE
OTHER MODELS WE DID MAKE SOME ADJUSTMENTS TO INCREASE POPS OVER
THE SOUTHERN HALF OF THE NORTHLAND...AND INCREASED SNOW AMOUNTS A
BIT ACROSS THE FAR SOUTH.
&&
.SHORT TERM...(THIS EVENING THROUGH THURSDAY)
ISSUED AT 330 PM CST WED DEC 18 2013
CURRENT SFC ANALYSIS DEPICTS A WELL DEFINED COLD FRONT PUSHING
INTO NW MINN. THIS BAROCLINIC ZONE AND TRANSITION TO CAA WILL BE
THE FOCUS FOR INCREASING CLOUDS AND SCT -SN/FLURRIES OVERNIGHT.
LITTLE OR NO SNOW ACCUM IS EXPECTED. HOWEVER...VSBY MAY BE
REDUCED TO AROUND A MILE AT TIMES DUE TO THE COMBO OF FALLING SN
AND GUSTY WINDS.
HAVE ISSUED A WIND CHILL ADVISORY FOR KOOCH COUNTY LATE TONIGHT
THROUGH THURS MORNING...WITH THE LOWEST WIND CHILL VALUES EXPECTED
DURING THE 0500-1000 AM WINDOW. LATEST BUFR SOUNDINGS SHOW
INVERSION HEIGHTS INCREASE TO 3 KFT AS THE FRONT PASSES AND THE
COLD CANADIAN AIR SURGES BACK IN THE REGION. EXPECT WINDS TO
BECOME GUSTY OVERNIGHT...MAINLY AFTER 06-08Z. THE CAA WILL
CONTINUE THURSDAY...WITH TEMPS ONLY REACHING THE LOW SINGLE
DIGITS ALONG THE BORDERLAND.
HAVE KEPT SMALL CHC POPS ALONG THE SOUTH SHORE OF LAKE SUPERIOR
THURSDAY AS WINDS/LAPSE RATES BECOME FAVORABLE FOR LAKE
EFFECT/ENHANCED SNOW SHOWERS. LIMITING FACTOR FOR SNOW WILL BE
LACK OF MID-LEVEL MOISTURE AND MARGINAL INVERSION HEIGHTS ONLY
AROUND 4 KFT. THE MOISTURE AND INVERSION HEIGHTS BECOME MORE
FAVORABLE FOR LES ALONG THE SOUTH SHORE THURSDAY NIGHT.
.LONG TERM...(THURSDAY NIGHT THROUGH WEDNESDAY)
ISSUED AT 330 PM CST WED DEC 18 2013
CONFIDENCE MODERATE THIS PERIOD AS MDLS MAINTAIN GOOD CONTINUITY
REGARDING OVERALL SYNOPTIC SCALE PATTERN. TWO BRANCHES OF THE
JETSTREAM WILL AMPLIFY WITH SRN BRANCH CYCLOGENESIS EXPECTED TO
DEVELOP SOUTH AND THEN EAST OF REGION. NRN BRANCH WILL DELIVER
SEVERAL EPISODES OF COLD AIR INTO THE NEW WEEK. INITIAL SFC LOW WILL
MOVE FROM SRN PLAINS INTO NRN IL THUR NIGHT. HIGHEST POPS WILL BE
CONFINED TO SERN TIER OF CWA WHERE SOME ACCUMULATION IS EXPECTED.
LAKE CONTRIBUTION MAY ALLOW SOME EXPANSION OF PRECIP SHIELD FARTHER
NORTH TOWARD TWIN PORTS. PROGRESSIVE NATURE OF SYSTEM AND CONVERGENT
FLOW ALOFT SHOULD MINIMIZE POTENTIAL FOR SIG PRECIP WITH THIS
FEATURE. SOME QUESTION AS TO WHETHER MID LVL FRONTOGENESIS MAY
AUGMENT PRECIP FARTHER NORTH BUT TREND HAS BEEN TO KEEP
FRONTOGENESIS POTENTIAL FARTHER SOUTH. COLD AND RELATIVELY DRY WX IS
ANTICIPATED FRIDAY/SATURDAY EXCEPT IN NORTH AND EAST CWA WHERE LAKE
INFLUENCE MAY PRODUCE SOME SNOWFALL. A SECOND AND MORE POTENT SFC
LOW WILL ORGANIZE OVER LOWER MS VALLEY SAT EVENING AND AIM TOWARDS
WRN IN BY EARLY SUNDAY. AS THIS SYSTEM MOVES NORTHEAST THE SOMEWHAT
PHASED BRANCHES OF THE UPPER JET SHOULD ALLOW FOR DEVELOPMENT OF AN
INVERTED SFC TROUGH INTO ERN HALF OF CWA. SFC LOW WINDS UP OVER ERN
GT LAKES SUNDAY. THE INVERTED SFC TROUGH IS FCST TO EXTEND WELL
WESTWARD INTO ERN CWA AS UPPER TROUGH IN NRN BRANCH MIGRATES
OVERHEAD. LATEST FCST OF SFC PRESSURE PATTERN WOULD FAVOR AN
EXTENDED PERIOD OF LES POTENTIAL ACROSS THE SOUTH SHORE FROM SUNDAY
INTO MONDAY. INITIAL GLANCE AT INSTABILITY/INVERSION HEIGHT/DEEP
LAYER MOISTURE PARAMETERS SUGGEST SIG ACCUMULATION POTENTIAL. THE
FCST WIND DIRECTION ALLOWS CONSIDERABLE FETCH INTO
BAYFIELD/IRON/ASHLAND COUNTIES ALTHOUGH IT IS TOO UNCERTAIN AT WHAT
RATE THE WIND WILL SHIFT DIRECTION AS THE SYSTEM TO THE EAST PULLS
FARTHER AWAY. TEMPS WILL REMAIN BLO CLIMO THROUGHOUT THE PERIOD.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z THURSDAY NIGHT)
ISSUED AT 1133 PM CST WED DEC 18 2013
THE COLD FRONT HAS PASSED THROUGH MUCH OF THE NORTHLAND THIS
EVENING...WITH AN AREA OF MVFR CEILINGS OCCURRING OVER PORTIONS OF
WESTERN/NORTHERN MINNESOTA. WE INCREASED THE COVERAGE/TIMING OF
MVFR CEILINGS BASED ON LATEST SATELLITE AND OBSERVATIONS. THERE
MAY BE SOME FLURRIES OR A BRIEF SNOW SHOWER THAT OCCURS...BUT
OBSERVATIONS AND RADAR SHOW LIMITED COVERAGE THOUGH. THE RUC AND
SATELLITE SUGGEST THESE LOWER CEILINGS WILL DISSIPATE OVERNIGHT OR
EARLY THURSDAY MORNING. NORTH-NORTHEAST WINDS OVER LAKE SUPERIOR
THURSDAY SHOULD CAUSE LAKE CLOUDS TO DEVELOP AND AFFECT KHYR WITH
MVFR CEILINGS.
A WEAK WAVE WILL RIDE ALONG A BAROCLINIC ZONE THURSDAY
NIGHT...SPREADING LIGHT SNOW TO AREAS ALONG AND SOUTH OF HIGHWAY
2. MVFR/IFR CONDITIONS WILL OCCUR THROUGH THE EARLY MORNING HOURS
AS THE AREA OF SNOW PASSES THROUGH.
&&
.PRELIMINARY POINT TEMPS/POPS...
DLH 1 13 -3 10 / 20 10 50 10
INL -11 2 -18 6 / 50 0 10 0
BRD 1 10 -6 8 / 20 10 60 0
HYR 6 18 7 14 / 10 20 90 10
ASX 5 19 10 15 / 20 30 60 20
&&
.DLH WATCHES/WARNINGS/ADVISORIES...
MN...WIND CHILL ADVISORY UNTIL NOON CST THURSDAY FOR MNZ010.
WI...NONE.
LS...SMALL CRAFT ADVISORY UNTIL 4 PM CST THURSDAY FOR LSZ121-146>148.
&&
$$
UPDATE...MELDE
SHORT TERM...GRANING
LONG TERM...CANNON
AVIATION...MELDE
AREA FORECAST DISCUSSION...UPDATED
NWS PORTLAND OR
1213 AM PST THU DEC 19 2013
.SYNOPSIS..RAIN AND SNOW SHOWERS WILL DIMINISH THROUGH THE EVENING.
CLEARING SKIES WILL DEVELOP FROM NORTH TO SOUTH TONIGHT...LEADING TO
COLDER OVERNIGHT LOWS AND THE POTENTIAL FOR ICY ROAD SURFACES FOR
TOMORROW MORNING. THERE WILL ALSO BE A FEW PATCHES OF FREEZING FOG
IN THE LOWLANDS. THERE WILL BE A BREAK IN PRECIPITATION TOMORROW
BEFORE A WARMER SYSTEM BRINGS RAIN AND MOUNTAIN SNOW ON FRI. IT
CONTINUES TO LOOK LIKE NORTHERN VALLEY LOCATIONS MAY SEE PRECIP
START AS SNOW FRI MORNING. TEMPS WILL WARM SIGNIFICANTLY LATER
FRI...WITH MODERATE TO HEAVY RAIN EXPECTED OVER MOST OF THE AREA. AN
UPPER LEVEL RIDGE WILL SET UP OVER THE NE PAC LATE IN THE
WEEK...WITH SEVERAL SYSTEMS PUSHING OVER THE TOP OF THE RIDGE
THROUGH EARLY NEXT WEEK.
&&
.UPDATE...JUST ISSUED ANOTHER QUICK FORECAST TO HANDLE THE PATCHY
FREEZING FOG DEVELOPING ACROSS THE LOWLANDS. SOME PATCHES OF
FREEZING FOG ARE BEING OBSERVED AT THE COAST NEAR ASTORIA...AS WELL
AS PORTIONS OF THE WILLAMETTE VALLEY AND SW WASHINGTON INTERIOR
LOWLANDS. ALSO DROPPED THE TEMPERATURES A FEW DEGREES...WITH RAPIDLY
CLEARING SKIES THEY HAVE FALLEN BELOW FREEZING A LITTLE FASTER THAN
PREVIOUSLY EXPECTED. WEAGLE
&&
.PREV DISCUSSION... /ISSUED 842 PM PST WED DEC 18 2013/
UPDATE...HOPEFULLY YOU ARE ALL NOT CONFUSED BY NOW BY OUR
TECHNOLOGICAL CHALLENGES...BUT THE LATEST SPECIAL WEATHER STATEMENT
FOR SLICK ROADS IS FOR TOMORROW MORNINGS COMMUTE...THURSDAY MORNING
AND NOT FRIDAY MORNING.
LATEST GRIDS ARE BEING SENT TO REFLECT LESS IN THE WAY OF FOG
TONIGHT. COLD AIR ADVECTION AND MOISTURE PROFILES DECREASING WITH
HEIGHT IN THE LOWEST LEVELS COUPLES WITH CLEARING SKIES TO SUGGEST
TEMPERATURES IN MOST PLACES WILL BE CHASING DEWPOINTS TONIGHT AND
LIMIT FOG POTENTIAL. OTHERWISE...WET ROADS AND MOST PLACES DIPPING
TO NEAR FREEZING (URBAN AREAS) OR BELOW MEANS THAT THERE WILL LIKELY
BE SOME SLICK OR ICY SPOTS ON ROADWAYS LATE TONIGHT INTO EARLY
FRIDAY.
THERE ARE SOME SHOWERS OUT THERE MOSTLY IN THE FORM OF RAIN...BUT
EXPECT TO SEE SOME SNOWFLAKES MIXED IN AT TIMES EVEN AT THE LOWEST
ELEVATIONS...AS HAS BEEN REPORTED IN ALBANY THIS EVENING. THERE ARE
SOME CONVERGENCE ZONE SHOWERS NORTH OF THE AREA THAT ARE PUSHING
THROUGH LEWIS COUNTY WASHINGTON. LATEST HRRR SUGGESTS THESE DIE OUT
BEFORE GETTING INTO OUR AREA...THOUGH POSSIBLY SOME FLAKES AS WELL
FOR COWLITZ COUNTY. /KMD
SHORT TERM...TONIGHT THROUGH SATURDAY... A COLD UPPER LEVEL TROUGH
IS BRINGING INCREASING SHOWERS AND LOWERING SNOW LEVELS ACROSS THE
REGION THIS AFTERNOON. THE BEST SHOWERS ACTIVITY IS CURRENTLY BEING
OBSERVED OVER THE S WA/N OR COAST AND COAST RANGE AND WILLAPA HILLS.
AS THE TROUGH CONTINUES TO PUSH SOUTH THE FOCUS OF THE SHOWER
ACTIVITY WILL BECOME FOCUSED OVER THE N WILLAMETTE VALLEY AND
CENTRAL OR COAST DURING THE LATE AFTERNOON...THEN OVER THE
CENTRAL/SOUTHERN VALLEY THIS EVENING. AS THE COLD AIR MOVES IN
ALOFT...SNOW LEVELS SHOULD FALL DOWN INTO THE COAST RANGE AND
CASCADE FOOTHILLS...BUT ONLY LIGHT ACCUMULATIONS ARE EXPECTED. THE
POTENTIAL FOR ANY SNOW REACHING DOWN TO VALLEY FLOOR LOCATIONS LOOKS
TO BE LOW. BY THE TIME IT IS COLD ENOUGH...IT APPEARS THAT SHOWER
ACTIVITY WILL BE BASICALLY OVER. BUT IF WE DO MANAGE TO SEE ANY
SHOWERS LATER THIS EVENING...A FEW SPOTS MIGHT SEE SNOW MIXING IN
WITH THE RAIN. THE FCST MODELS ARE INDICATING RAPID CLEARING TONIGHT
FROM NORTH TO SOUTH AS COLD AIR STREAMS IN BEHIND THE UPPER LEVEL
TROUGH AXIS. BASED ON THE CLEARING APPARENT ON VISIBLE SATELLITE
OVER THE OLYMPIC PENINSULA AND ADJACENT COASTAL WATERS...THE MODELS
ARE LIKELY CORRECT ABOUT THIS. THUS THE CURRENT FCST STARTS TO CLEAR
THINGS IN THE NORTHERN TIER OF THE FCST AREA LATE THIS
EVENING...THEN CLEARING OUT DOWN SOUTH OVERNIGHT INTO EARLY TOMORROW
MORNING. THIS SHOULD ALLOW TEMPS TO FALL SIGNIFICANTLY
OVERNIGHT...LEADING TO SOME CONCERN THAT ANY MOISTURE ON ROAD
SURFACE TONIGHT MAY FREEZE AND CREATE SOME SLIPPERY CONDITIONS FOR
TOMORROW MORNING/S COMMUTE. THERE IS ALSO A HIGH LIKELIHOOD THAT
AREAS OF FOG WILL FORM EARLY TOMORROW MORNING AS UPPER LEVEL RIDGING
BEGINS TO BUILD IN ALOFT.
TOMORROW SHOULD PROVIDE A RELATIVELY QUIET DAY AS THE SHORTWAVE UPPER
LEVEL RIDGING IS OVER THE REGION. ANY LOW LEVEL CLOUDS OR FOG SHOULD
DISSIPATE DURING THE DAY...PROVIDING SOME SUN BREAKS FOR MOST. HIGH
CLOUDS MAY BEGIN TO STREAM IN ALOFT LATE TOMORROW AHEAD OF THE NEXT
SYSTEM THAT IS SLATED TO IMPACT US ON FRI.
THE MODEL SOLUTIONS FOR THE FRI SYSTEM CONTINUE TO RAISE CONCERNS OF
A WINTRY MIX AT SOME LOW ELEVATION SITES TO START THE EVENT. THE 12Z
UW WRF-GFS IS INDICATING THAT SOME LIGHT SNOW ACCUMULATIONS ARE
POSSIBLE BEFORE DAY BREAK FRI FOR THE LOWER COLUMBIA BASIN AND I-5
CORRIDOR IN S WA. IT ALSO INDICATES THE POTENTIAL FOR SOME LIGHT SNOW
FALLING INTO THE PORTLAND METRO AREA AROUND THE FRI MORNING COMMUTE.
THE SYSTEM IS FCST TO BRING SOME FAIRLY STRONG SW WINDS AT THE LOW
LEVELS TO SCOUR OUT THE COLD AIR...AND THE COLD POOL LEADING OVER THE
REGION LEADING INTO THE EVENT IS NOT EXPECTED TO BE VERY DEEP. SO THE
CHANCES FOR A HIGH IMPACT EVENT DO NOT APPEAR TO BE VERY GOOD.
HEAVIER RAIN WILL SPREAD OVER THE REGION LATER WED MORNING AND
AFTERNOON...WITH SNOW LEVELS RISING RAPIDLY INTO THE HIGHER CASCADE
TERRAIN. IT APPEARS THAT MOST LOCATIONS WILL GET A SHOT OF MODERATE
RAIN BY FRI NIGHT. PRECIP IS MODELED TO TAPER OFF FRI NIGHT INTO
EARLY SAT...LEAVING JUST A MILDER AND CLOUDY DAY ON SAT IN ONSHORE
FLOW. PYLE
LONG TERM...SATURDAY NIGHT THROUGH TUESDAY...UPPER LEVEL RIDGING
OVER THE EPAC WILL DOMINATE MUCH OF THE EXTENDED FORECAST. THIS WILL
CONTINUE THE NORTHWESTERLY UPPER LEVEL FLOW THROUGH THE PERIOD...AND
PREVENT ANY SUBSTANTIAL SYSTEMS FROM AFFECTING THE AREA. WARM FRONT
ON SUNDAY FOLLOWED BY A DECAYING COLD FRONT ON MONDAY WILL BRING
MOISTURE INTO THE PAC NW FROM TIME TO TIME...HOWEVER THE PRECIP WILL
GENERALLY REMAIN CONFINED TO THE MORE NORTHERN AREAS OF THE CWA. BY
LATE MONDAY THE MODELS DIVERGE...WITH THE ECMWF ALLOWING COLD NORTH
OR NORTHEASTERLY UPPER FLOW TO DEVELOP AS AN UPPER TROUGH DIVES
SOUTH INTO THE GREAT BASIN FROM CANADA. HOWEVER...THE GFS PHASES
THAT LOW WITH A LONGWAVE TROUGH OVER THE MID-WEST...WHICH WOULD
LEAVE THE PACNW UNDER CONTINUED HIGH PRESSURE ALOFT. BURGESS
&&
.AVIATION...06Z TAF PACKAGE. AIR MASS CHANGE CONTINUES BUT AM
FEELING FAR LESS CONVINCED THERE WILL BE WIDESPREAD FOG/STRATUS
ACROSS THE AREA TONIGHT. MODELS INDICATE COLD ADVECTION WILL BRING
CONTINUOUSLY LOWERING DEW POINTS TONIGHT AND THE TEMPERATURE SEEMS
LIKE IT WILL NOT BE ABLE TO QUITE MATCH PACE. AM ONLY MODERATELY
CONFIDENT IN THE APPROACH SO CONTINUED TO HINT AT IMPACTS VIA
REDUCED VSBYS BUT DID MAKE THE LOW CLOUDS SCATTERED. THE EXCEPTION
WILL BE KEUG WHERE THE LOW DECK NEVER LEFT TODAY DESPITE THE SHOWERS
PLUS LIGHT NORTHERLY WINDS WILL PACK MOISTURE TO THE SOUTH END OF
THE WILLAMETTE VALLEY. THEY WILL LIKELY REMAIN UNDER THE FOG/STRATUS
INFLUENCE TOWARD THURSDAY AFTERNOON. BIGGER PROBLEM ACROSS THE AREA
MAY BE WATER ON THE RUNWAYS AND RAMPS TURNING TO ICE AS TEMPERATURES
FALL TO BELOW FREEZING TONIGHT.
KPDX AND APPROACHES...CLOUDS RAPIDLY CLEARING TONIGHT BEHIND THE
FRONT. NO LONGER EXPECT SIGNIFICANT FOG OR STRATUS TO IMPACT THE
FIELD. STILL HINTED AT THE POSSIBILITY BUT FEEL THE MOST LIKELY
SCENARIO WILL KEEP SKIES RELATIVELY CLEAR. DO HAVE CONCERNS FOR
LEFTOVER LIQUID ON THE GROUND TO FREEZE UP ON THE RAMPS AND
RUNWAYS. ICY CONDITIONS MAY HOLD OFF UNTIL JUST BEFORE SUNRISE.
/JBONK
&&
.MARINE...COLD FRONT HAS LARGELY CLEARED THE WATERS AS OF THIS
HOUR. GUSTY NORTHERLY WINDS HAVE INCREASED AS EXPECTED AND SIT
SOLIDLY IN SMALL CRAFT ADVISORY RANGE. THE SWELL HAS BEEN SLOW TO
RISE BUT THE WIND WAVES SEEM TO BE MAKING UP FOR IT AT THIS TIME.
WILL KEEP THE ADVISORIES GOING, IF FOR NOTHING ELSE, AS SEAS
ARE SQUARING UP UNDER THE WIND WAVES AND/OR DEVELOPING FRESH
SWELL.
BRIEF BREAK IN THE ACTION LATER TOMORROW THROUGH FRIDAY MORNING.
A STRONGER SYSTEM BRINGS POTENTIALLY STRONGER GALE FORCE GUSTS AND
SEAS IN THE LOW TEENS FRIDAY AFTERNOON THROUGH EARLY SUNDAY.
/JBONK
&&
.PQR WATCHES/WARNINGS/ADVISORIES...
OR...NONE.
WA...NONE.
PZ...SMALL CRAFT ADVISORY FOR WINDS UNTIL NOON PST THURSDAY FOR
COASTAL WATERS FROM CAPE SHOALWATER WA TO FLORENCE OR OUT 60 NM.
SMALL CRAFT ADVISORY FOR HAZARDOUS SEAS UNTIL NOON PST THURSDAY
FOR COASTAL WATERS FROM CAPE SHOALWATER WA TO FLORENCE OR OUT 60
NM.
&&
$$
MORE WEATHER INFORMATION ONLINE AT..
HTTP://WEATHER.GOV/PORTLAND
INTERACT WITH US VIA SOCIAL MEDIA
WWW.FACEBOOK.COM/US.NATIONALWEATHERSERVICE.PORTLAND.GOV
WWW.TWITTER.COM/NWSPORTLAND
THIS DISCUSSION IS FOR NORTHWEST OREGON AND SOUTHWEST WASHINGTON FROM
THE CASCADE CREST TO 60 NAUTICAL MILES OFFSHORE. THE AREA IS COMMONLY
REFERRED TO AS THE FORECAST AREA.
AREA FORECAST DISCUSSION...UPDATED
NWS PORTLAND OR
842 PM PST WED DEC 18 2013
UPDATED AVIATION AND MARINE DISCUSSIONS
.SYNOPSIS..RAIN AND SNOW SHOWERS WILL DIMINISH THROUGH THE EVENING.
CLEARING SKIS WILL DEVELOP FROM NORTH TO SOUTH TONIGHT...LEADING TO
COLDER OVERNIGHT LOWS AND THE POTENTIAL FOR ICY ROAD SURFACES FOR
TOMORROW MORNING. THERE WILL BE A BREAK IN PRECIPITATION TOMORROW
BEFORE A WARMER SYSTEM BRINGS RAIN AND MOUNTAIN SNOW ON FRI. IT
CONTINUES TO LOOK LIKE NORTHERN VALLEY LOCATIONS MAY SEE PRECIP
START AS SNOW FRI MORNING. TEMPS WILL WARM SIGNIFICANTLY LATER
FRI...WITH MODERATE TO HEAVY RAIN EXPECTED OVER MOST OF THE AREA. AN
UPPER LEVEL RIDGE WILL SET UP OVER THE NE PAC LATE IN THE
WEEK...WITH SEVERAL SYSTEMS PUSHING OVER THE TOP OF THE RIDGE
THROUGH EARLY NEXT WEEK.
&&
.UPDATE...HOPEFULLY YOU ARE ALL NOT CONFUSED BY NOW BY OUR
TECHNOLOGICAL CHALLENGES...BUT THE LATEST SPECIAL WEATHER STATEMENT
FOR SLICK ROADS IS FOR TOMORROW MORNINGS COMMUTE...THURSDAY MORNING
AND NOT FRIDAY MORNING.
LATEST GRIDS ARE BEING SENT TO REFLECT LESS IN THE WAY OF FOG
TONIGHT. COLD AIR ADVECTION AND MOISTURE PROFILES DECREASING WITH
HEIGHT IN THE LOWEST LEVELS COUPLES WITH CLEARING SKIES TO SUGGEST
TEMPERATURES IN MOST PLACES WILL BE CHASING DEWPOINTS TONIGHT AND
LIMIT FOG POTENTIAL. OTHERWISE...WET ROADS AND MOST PLACES DIPPING
TO NEAR FREEZING (URBAN AREAS) OR BELOW MEANS THAT THERE WILL LIKELY
BE SOME SLICK OR ICY SPOTS ON ROADWAYS LATE TONIGHT INTO EARLY
FRIDAY.
THERE ARE SOME SHOWERS OUT THERE MOSTLY IN THE FORM OF RAIN...BUT
EXPECT TO SEE SOME SNOWFLAKES MIXED IN AT TIMES EVEN AT THE LOWEST
ELEVATIONS...AS HAS BEEN REPORTED IN ALBANY THIS EVENING. THERE ARE
SOME CONVERGENCE ZONE SHOWERS NORTH OF THE AREA THAT ARE PUSHING
THROUGH LEWIS COUNTY WASHINGTON. LATEST HRRR SUGGESTS THESE DIE OUT
BEFORE GETTING INTO OUR AREA...THOUGH POSSIBLY SOME FLAKES AS WELL
FOR COWLITZ COUNTY.
/KMD
&&
.PREV DISCUSSION... /ISSUED 312 PM PST WED DEC 18 2013/
SHORT TERM...TONIGHT THROUGH SATURDAY... A COLD UPPER LEVEL TROUGH
IS BRINGING INCREASING SHOWERS AND LOWERING SNOW LEVELS ACROSS THE
REGION THIS AFTERNOON. THE BEST SHOWERS ACTIVITY IS CURRENTLY BEING
OBSERVED OVER THE S WA/N OR COAST AND COAST RANGE AND WILLAPA HILLS.
AS THE TROUGH CONTINUES TO PUSH SOUTH THE FOCUS OF THE SHOWER
ACTIVITY WILL BECOME FOCUSED OVER THE N WILLAMETTE VALLEY AND
CENTRAL OR COAST DURING THE LATE AFTERNOON...THEN OVER THE
CENTRAL/SOUTHERN VALLEY THIS EVENING. AS THE COLD AIR MOVES IN
ALOFT...SNOW LEVELS SHOULD FALL DOWN INTO THE COAST RANGE AND
CASCADE FOOTHILLS...BUT ONLY LIGHT ACCUMULATIONS ARE EXPECTED. THE
POTENTIAL FOR ANY SNOW REACHING DOWN TO VALLEY FLOOR LOCATIONS LOOKS
TO BE LOW. BY THE TIME IT IS COLD ENOUGH...IT APPEARS THAT SHOWER
ACTIVITY WILL BE BASICALLY OVER. BUT IF WE DO MANAGE TO SEE ANY
SHOWERS LATER THIS EVENING...A FEW SPOTS MIGHT SEE SNOW MIXING IN
WITH THE RAIN. THE FCST MODELS ARE INDICATING RAPID CLEARING TONIGHT
FROM NORTH TO SOUTH AS COLD AIR STREAMS IN BEHIND THE UPPER LEVEL
TROUGH AXIS. BASED ON THE CLEARING APPARENT ON VISIBLE SATELLITE
OVER THE OLYMPIC PENINSULA AND ADJACENT COASTAL WATERS...THE MODELS
ARE LIKELY CORRECT ABOUT THIS. THUS THE CURRENT FCST STARTS TO CLEAR
THINGS IN THE NORTHERN TIER OF THE FCST AREA LATE THIS
EVENING...THEN CLEARING OUT DOWN SOUTH OVERNIGHT INTO EARLY TOMORROW
MORNING. THIS SHOULD ALLOW TEMPS TO FALL SIGNIFICANTLY
OVERNIGHT...LEADING TO SOME CONCERN THAT ANY MOISTURE ON ROAD
SURFACE TONIGHT MAY FREEZE AND CREATE SOME SLIPPERY CONDITIONS FOR
TOMORROW MORNING/S COMMUTE. THERE IS ALSO A HIGH LIKELIHOOD THAT
AREAS OF FOG WILL FORM EARLY TOMORROW MORNING AS UPPER LEVEL RIDGING
BEGINS TO BUILD IN ALOFT.
TOMORROW SHOULD PROVIDE A RELATIVELY QUIET DAY AS THE SHORTWAVE UPPER
LEVEL RIDGING IS OVER THE REGION. ANY LOW LEVEL CLOUDS OR FOG SHOULD
DISSIPATE DURING THE DAY...PROVIDING SOME SUN BREAKS FOR MOST. HIGH
CLOUDS MAY BEGIN TO STREAM IN ALOFT LATE TOMORROW AHEAD OF THE NEXT
SYSTEM THAT IS SLATED TO IMPACT US ON FRI.
THE MODEL SOLUTIONS FOR THE FRI SYSTEM CONTINUE TO RAISE CONCERNS OF
A WINTRY MIX AT SOME LOW ELEVATION SITES TO START THE EVENT. THE 12Z
UW WRF-GFS IS INDICATING THAT SOME LIGHT SNOW ACCUMULATIONS ARE
POSSIBLE BEFORE DAY BREAK FRI FOR THE LOWER COLUMBIA BASIN AND I-5
CORRIDOR IN S WA. IT ALSO INDICATES THE POTENTIAL FOR SOME LIGHT SNOW
FALLING INTO THE PORTLAND METRO AREA AROUND THE FRI MORNING COMMUTE.
THE SYSTEM IS FCST TO BRING SOME FAIRLY STRONG SW WINDS AT THE LOW
LEVELS TO SCOUR OUT THE COLD AIR...AND THE COLD POOL LEADING OVER THE
REGION LEADING INTO THE EVENT IS NOT EXPECTED TO BE VERY DEEP. SO THE
CHANCES FOR A HIGH IMPACT EVENT DO NOT APPEAR TO BE VERY GOOD.
HEAVIER RAIN WILL SPREAD OVER THE REGION LATER WED MORNING AND
AFTERNOON...WITH SNOW LEVELS RISING RAPIDLY INTO THE HIGHER CASCADE
TERRAIN. IT APPEARS THAT MOST LOCATIONS WILL GET A SHOT OF MODERATE
RAIN BY FRI NIGHT. PRECIP IS MODELED TO TAPER OFF FRI NIGHT INTO
EARLY SAT...LEAVING JUST A MILDER AND CLOUDY DAY ON SAT IN ONSHORE
FLOW. PYLE
LONG TERM...SATURDAY NIGHT THROUGH TUESDAY...UPPER LEVEL RIDGING
OVER THE EPAC WILL DOMINATE MUCH OF THE EXTENDED FORECAST. THIS WILL
CONTINUE THE NORTHWESTERLY UPPER LEVEL FLOW THROUGH THE PERIOD...AND
PREVENT ANY SUBSTANTIAL SYSTEMS FROM AFFECTING THE AREA. WARM FRONT
ON SUNDAY FOLLOWED BY A DECAYING COLD FRONT ON MONDAY WILL BRING
MOISTURE INTO THE PAC NW FROM TIME TO TIME...HOWEVER THE PRECIP WILL
GENERALLY REMAIN CONFINED TO THE MORE NORTHERN AREAS OF THE CWA. BY
LATE MONDAY THE MODELS DIVERGE...WITH THE ECMWF ALLOWING COLD NORTH
OR NORTHEASTERLY UPPER FLOW TO DEVELOP AS AN UPPER TROUGH DIVES
SOUTH INTO THE GREAT BASIN FROM CANADA. HOWEVER...THE GFS PHASES
THAT LOW WITH A LONGWAVE TROUGH OVER THE MID-WEST...WHICH WOULD
LEAVE THE PACNW UNDER CONTINUED HIGH PRESSURE ALOFT. BURGESS &&
.AVIATION...06Z TAF PACKAGE. AIR MASS CHANGE CONTINUES BUT AM
FEELING FAR LESS CONVINCED THERE WILL BE WIDESPREAD FOG/STRATUS
ACROSS THE AREA TONIGHT. MODELS INDICATE COLD ADVECTION WILL BRING
CONTINUOUSLY LOWERING DEW POINTS TONIGHT AND THE TEMPERATURE SEEMS
LIKE IT WILL NOT BE ABLE TO QUITE MATCH PACE. AM ONLY MODERATELY
CONFIDENT IN THE APPROACH SO CONTINUED TO HINT AT IMPACTS VIA
REDUCED VSBYS BUT DID MAKE THE LOW CLOUDS SCATTERED. THE EXCEPTION
WILL BE KEUG WHERE THE LOW DECK NEVER LEFT TODAY DESPITE THE SHOWERS
PLUS LIGHT NORTHERLY WINDS WILL PACK MOISTURE TO THE SOUTH END OF
THE WILLAMETTE VALLEY. THEY WILL LIKELY REMAIN UNDER THE FOG/STRATUS
INFLUENCE TOWARD THURSDAY AFTERNOON. BIGGER PROBLEM ACROSS THE AREA
MAY BE WATER ON THE RUNWAYS AND RAMPS TURNING TO ICE AS TEMPERATURES
FALL TO BELOW FREEZING TONIGHT.
KPDX AND APPROACHES...CLOUDS RAPIDLY CLEARING TONIGHT BEHIND THE
FRONT. NO LONGER EXPECT SIGNIFICANT FOG OR STRATUS TO IMPACT THE
FIELD. STILL HINTED AT THE POSSIBILITY BUT FEEL THE MOST LIKELY
SCENARIO WILL KEEP SKIES RELATIVELY CLEAR. DO HAVE CONCERNS FOR
LEFTOVER LIQUID ON THE GROUND TO FREEZE UP ON THE RAMPS AND
RUNWAYS. ICY CONDITIONS MAY HOLD OFF UNTIL JUST BEFORE SUNRISE.
/JBONK
&&
.MARINE...COLD FRONT HAS LARGELY CLEARED THE WATERS AS OF THIS
HOUR. GUSTY NORTHERLY WINDS HAVE INCREASED AS EXPECTED AND SIT
SOLIDLY IN SMALL CRAFT ADVISORY RANGE. THE SWELL HAS BEEN SLOW TO
RISE BUT THE WIND WAVES SEEM TO BE MAKING UP FOR IT AT THIS TIME.
WILL KEEP THE ADVISORIES GOING, IF FOR NOTHING ELSE, AS SEAS
ARE SQUARING UP UNDER THE WIND WAVES AND/OR DEVELOPING FRESH
SWELL.
BRIEF BREAK IN THE ACTION LATER TOMORROW THROUGH FRIDAY MORNING.
A STRONGER SYSTEM BRINGS POTENTIALLY STRONGER GALE FORCE GUSTS AND
SEAS IN THE LOW TEENS FRIDAY AFTERNOON THROUGH EARLY SUNDAY.
/JBONK
&&
.PQR WATCHES/WARNINGS/ADVISORIES...
OR...NONE.
WA...NONE.
PZ...SMALL CRAFT ADVISORY FOR WINDS UNTIL NOON PST THURSDAY FOR
COASTAL WATERS FROM CAPE SHOALWATER WA TO FLORENCE OR OUT 60 NM.
SMALL CRAFT ADVISORY FOR HAZARDOUS SEAS UNTIL NOON PST THURSDAY
FOR COASTAL WATERS FROM CAPE SHOALWATER WA TO FLORENCE OR OUT 60
NM.
&&
$$
MORE WEATHER INFORMATION ONLINE AT..
HTTP://WEATHER.GOV/PORTLAND
INTERACT WITH US VIA SOCIAL MEDIA
WWW.FACEBOOK.COM/US.NATIONALWEATHERSERVICE.PORTLAND.GOV
WWW.TWITTER.COM/NWSPORTLAND
THIS DISCUSSION IS FOR NORTHWEST OREGON AND SOUTHWEST WASHINGTON FROM
THE CASCADE CREST TO 60 NAUTICAL MILES OFFSHORE. THE AREA IS COMMONLY
REFERRED TO AS THE FORECAST AREA.
AREA FORECAST DISCUSSION...UPDATED
NWS ABERDEEN SD
348 AM CST THU DEC 19 2013
.SHORT TERM...TODAY THROUGH SATURDAY
MAIN FORECAST CHALLENGE TODAY IS SNOW ACCUMULATIONS ACROSS THE
REGION.
CURRENTLY RADAR SHOWS A VERY THIN BAND OF JET STREAK ENHANCED
SNOW ALONG THE WESTERN AND CENTRAL ND/SD STATE LINE. ONLY
HETTINGER IS REPORTING SNOW WITH SIGNIFICANT VSBY REDUCTIONS BUT
WITH FEW OTHER OBS SITES IN THE BAND WILL GIVE A BEST GUESS THAT
THERE HAS TO BE AT LEAST SOME LIGHT SNOW STRETCHING EAST TOWARD
EUREKA. MODEL GUIDANCE OVERALL SHOWS A SIMILAR PICTURE...AT LEAST
ON THE BROAD SCALE. HOWEVER RECENT HI-RES MODEL RUNS DIFFER
GREATLY IN THE DETAILS. THE HRRR IS VERY SLOW TO PROGRESS ANY
PRECIP ACROSS THE SOUTHERN COUNTIES...KEEPING EVEN PIERRE DRY
UNTIL 18Z. STUCK PRETTY CLOSE TO THE LOCAL 4KM FOR HOURLY POPS.
BUT EVEN THIS SOLUTION IS TRICKY BECAUSE IT BRINGS SIGNIFICANTLY
DRIER AIR INTO THE NORTHEASTERN CWA...KEEPING AREAS ALONG HWY 12
AND NORTH PRECIP FREE EAST OF BROWN COUNTY. WHEREAS 00Z RUNS OF
THE ECMWF/GFS/NAM ARE HITTING THE NORTHERN CWA HARDER THAN IN
PREVIOUS RUNS.
SO PLACEMENT OF THE MAIN FIELD OF QPF HAS LOW FORECASTER
CONFIDENCE TODAY. TO COMPOUND THE CHALLENGE SOME MODELS HAVE THE
SFC HIGH DROPPING IN A LITTLE MORE QUICKLY AND IN DIFFERENT AREAS
OF THE CWA WHICH WILL AFFECT WIND SPEEDS AND SNOW RATIOS. STUCK
WITH A 15:1 RATIO AND SOME AREAS OF BLOWING SNOW...BUT IF THE
WINDS REALLY DIE DOWN THAT COULD MEAN RATIOS CLOSER TO 20:1 AND
LESS OF A BLOWING SNOW CONCERN. CURRENTLY HAVE STORM TOTAL SNOW
AMOUNTS OF 2 TO 4 INCHES WITH HIGHEST AMOUNTS NEAR THAT JET STREAK
ON THE ND/SD BORDER AND WEST OF THE MISSOURI RIVER.
AS THE ARCTIC FRONT MOVES FROM NORTH TO SOUTH TODAY TEMPS WILL
REMAIN STEADY OR FALL THROUGH THE DAY. THEN THE COLD AIR SETTLES
IN THROUGH THE REMAINDER OF THE PERIOD.
.LONG TERM...SATURDAY NIGHT THROUGH WEDNESDAY
THE MODELS AND GFS ENSEMBLES AGREE WELL THROUGH THE LONG TERM WITH
KEEPING THE REGION ON THE COLDER SIDE OF NORMAL. THE UPPER LEVEL
FLOW OVER THE REGION REMAINS FROM THE NORTHWEST THROUGH THE LONG
TERM WITH SHORT WAVE TROUGHS/CLIPPER SYSTEMS DROPPING ACROSS THE
REGION. ONE OR MORE OF THESE SYSTEMS MAY END UP BEING MORE
SIGNIFICANT AS FAR AS BRINGING SOME ACCUMULATING SNOWFALL AND
STRONG WINDS BUT TOO DIFFICULT TO SINGLE OUT AT THIS TIME. HAVE
THE LONG TERM BASICALLY DRY FOR NOW UNTIL THERE IS BETTER MODEL
AGREEMENT WITH THESE CLIPPER SYSTEMS. AT THIS TIME...THE EC WAS
SHOWING A COUPLE CLIPPERS MOVING ACROSS FOR EARLY THROUGH MID WEEK
THAT MAY BRING SOME LIGHT SNOW AND STRONG WINDS. HAVE IN SLIGHT
CHANCES OF LIGHT SNOW ACROSS THE NORTHEAST CWA FOR THE FIRST
CLIPPER SYSTEM ON MONDAY NIGHT. OTHERWISE...MUCH BELOW NORMAL
TEMPERATURES WILL CONTINUE WITH MAYBE SOME MODERATION CLOSER TO
NORMAL BY TUESDAY AND WEDNESDAY. THE ADDITIONAL SNOWFALL TODAY AND
THIS EVENING WILL HAVE A BIG INFLUENCE ON THE TEMPERATURES IN THE
LONG TERM AS ARCTIC AIR MASSES MOVE ACROSS THE REGION. SATURDAY
NIGHT AND SUNDAY NIGHT ARE EXPECTED TO BE IN THE SINGLE DIGITS AND
TEENS BELOW ZERO. HIGHS ON SUNDAY AND MONDAY WILL BE MAINLY IN THE
SINGLE DIGITS EITHER SIDE OF ZERO. TUESDAY AND WEDNESDAY AT THIS
TIME ARE EXPECTED TO BE BACK IN THE UPPER TEENS AND 20S. THIS MAY
END UP CHANGING AS THE MODELS EVOLVE.
&&
.AVIATION...
06Z TAFS FOR THE KABR...KATY...KPIR AND KMBG TERMINALS
MVFR CIGS WILL SPREAD OVER THE AREA THROUGH THE OVERNIGHT
HOURS...WITH THE POSSIBILITY OF CIGS DROPPING INTO THE IFR
CATEGORY AT TIMES. WIDESPREAD LIGHT SNOW WILL SPREAD FROM WEST TO
EAST DURING THE AFTERNOON HOURS ON THURSDAY...WITH MAINLY MVFR
VSBYS EXPECTED.
&&
.ABR WATCHES/WARNINGS/ADVISORIES...
SD...WINTER WEATHER ADVISORY UNTIL 7 PM CST /6 PM MST/ THIS EVENING
FOR BUFFALO-CAMPBELL-CORSON-DEWEY-EDMUNDS-FAULK-HAND-HUGHES-
HYDE-JONES-LYMAN-MCPHERSON-POTTER-STANLEY-SULLY-WALWORTH.
MN...NONE.
&&
$$
SHORT TERM...WISE
LONG TERM...MOHR
AVIATION...MOHR
WEATHER.GOV/ABERDEEN
AREA FORECAST DISCUSSION
NWS TAUNTON MA
700 AM EST THU DEC 19 2013
.SYNOPSIS...
DRY AND MILDER WEATHER EXPECTED TODAY AS A COLD FRONT STALLS TO
OUR NORTH. THIS STALLED FRONT WILL RESULT IN PERIODS OF UNSETTLED
WEATHER FRI NIGHT THROUGH EARLY MON. DRIER AND COOLER WEATHER
ARRIVES EARLY NEXT WEEK.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
7 AM UPDATE...MADE VERY FEW CHANGES TO THE FORECAST AND THOSE TO
THE SKY GRIDS TO BETTER MATCH SATELLITE TRENDS. OTHERWISE...THE
FORECAST IS ON TRACK.
PREVIOUS DISCUSSION...
FOR THE REST OF TODAY...EXPECTING A DRY DAY WITH A HIGH PRESSURE
LOCATED ALONG THE SOUTHEAST USA COAST. THIS WILL RESULT IN A WEST
TO SOUTHWEST FLOW TODAY.
3.9 MICRON SATELLITE IMAGERY SHOWING ABUNDANT LOW-LEVEL MOISTURE
STREAMING EAST FROM THE GREAT LAKES THIS MORNING. THESE CLOUDS
HAVE SINCE COVERED MOST OF SOUTHERN NEW ENGLAND. WEST FLOW...
ALBEIT RELATIVELY LIGHT...THIS MORNING WILL INDUCE SOME
DOWNSLOPING. THUS THINKING THERE SHOULD BE MORE SUN THAN CLOUDS
TODAY...ONCE THE CURRENT CLOUDS IN OUR REGION MOVE EAST. THE
LATEST VERSION OF THE RAP SEEMED TO BE HANDLING THIS SITUATION
WELL...SO RELIED ON IT FOR TIMING.
IT WILL BE A LITTLE WARMER TODAY THAN YESTERDAY WITH THE SUNSHINE
AND WEST TO SOUTHWEST WINDS.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH 6 PM FRIDAY/...
A FRONTAL BOUNDARY WILL SLOWLY MOVE SOUTH THROUGH NORTHERN NEW
ENGLAND TONIGHT. THERE IS STILL SOME QUESTION AS TO EXACTLY HOW
MUCH PROGRESS IT WILL MAKE IN OUR DIRECTION. DEEPER MOISTURE STILL
SHOULD REMAIN NORTH OF OUR REGION FOR MOST OF TONIGHT. SO ONLY
HAVE A CHANCE OF SOME SOME PRECIPITATION VERY LATE TONIGHT INTO
FRIDAY NORTH OF I-90...MAINLY DURING THE DAYTIME FRIDAY.
THE TIMING OF THIS FRONT AND PRECIPITATION WILL BE CRUCIAL FOR
DETERMINING TYPE. THINKING THERE IS A POSSIBILITY FOR SOME LIGHT
ICING ACROSS SOUTHERN NH LATE TONIGHT...BUT IT SHOULD NOT BE VERY
WIDESPREAD. AS SUCH...HOLDING OFF ON ISSUING ANY FREEZING RAIN
ADVISORIES AT THIS TIME. NEXT SHIFT WILL HAVE TO MONITOR THIS
SITUATION. EVENTUALLY ANY PRECIPITATION IN OUR REGION SHOULD
TRANSITION TO ALL RAIN AS TEMPERATURES CONTINUE TO RISE FRIDAY
MORNING. WARMING TREND CONTINUES...WITH HIGHS GENERALLY IN THE 40S
FOR THE FIRST TIME IN SEVERAL DAYS FOR MOST OF THE INTERIOR.
&&
.LONG TERM /FRIDAY NIGHT THROUGH WEDNESDAY/...
* UNSETTLED WEATHER OVER THE WEEKEND
* DRIER...COOLER WEATHER EXPECTED EARLY NEXT WEEK
00Z NAM AND GFS ARE MORE PROGRESSIVE THAN THE ECMWF/UKMET/CANADIAN
WITH WAVES OF LOW PRESSURE MOVING ALONG A COLD FRONT STRETCHED
ACROSS NORTHERN NEW ENGLAND FRIDAY NIGHT AND SATURDAY. WITH THE
SUPPORT OF WPC...AM LEANING AWAY FROM THE NAM/GFS SOLUTION FOR THIS
PERIOD OF THE FORECAST. SUNDAY AND BEYOND...MODELS ARE IN
REMARKABLY GOOD AGREEMENT ON THE GENERAL SYNOPTIC SCALE PATTERN
THROUGH THE LONG TERM. WHILE THE MODELS DO SEEM TO BE NARROWING IN
THEIR RANGE OF SOLUTIONS...THERE IS STILL QUITE A BIT OF UNCERTAINTY
WHEN IT COMES TO THE TEMPERATURE PROFILE SATURDAY NIGHT AND SUNDAY.
THESE TEMPERATURE PROFILES...PARTICULARLY THE SURFACE TEMPERATURES
WILL PLAY A BIG ROLE IN PTYPE. AT THIS POINT...LOOKS LIKE ANY
FROZEN/FREEZING PRECIPITATION WILL BE LIMITED TO SOUTHERN NEW
HAMPSHIRE. THE ARCTIC FRONT MOVES THROUGH SOUTHERN NEW ENGLAND LATE
SUNDAY INTO EARLY MONDAY. THEN COOLER...DRIER WEATHER IS FORECAST
TO PERSIST THROUGH CHRISTMAS DAY.
FRIDAY NIGHT THROUGH SATURDAY...LIGHT PRECIPITATION IS POSSIBLE
ACROSS THE NORTHERN ZONES AS LOW PRESSURE MOVES THROUGH NORTHERN NEW
ENGLAND ALONG THE FRONT. QPF FORECASTS ARE LESS THAN A TENTH OF AN
INCH DURING THIS TIME. HOWEVER...LOOKS THAT SURFACE TEMPERATURES IN
SOUTHERN NEW HAMPSHIRE IN PARTICULAR ARE LIKELY TO BE BELOW
FREEZING. SO THERE IS LIKELY TO BE A PERIOD OF FREEZING RAIN IN
THIS AREA. A VERY MINIMAL TEMPERATURE CHANGE CAN MEAN THE
DIFFERENCE BETWEEN ICING AND REGULAR RAIN SO THIS WILL CONTINUE TO
BE MONITORED.
SATURDAY NIGHT THROUGH MONDAY MORNING...WHILE THE MODELS SEEM TO BE
TIGHTENING UP ON THEIR VARYING SOLUTIONS...THERE REMAINS SOME
UNCERTAINTY IN THE SURFACE TEMPERATURE FORECASTS. IT DOES LOOK LIKE
THERE IS POTENTIAL FOR A PERIOD OF FREEZING RAIN SOMEWHERE NORTH OF
ROUTE 2 IN MASSACHUSETTS AND INTO SOUTHERN NEW HAMPSHIRE. THIS SET
OF MODELS TOOK THE COLDER TEMPERATURES A BIT FARTHER NORTH THAN
PREVIOUS MODELS...KEEPING MOST...IF NOT ALL...OF THE CWA OUT OF THE
COLDER TEMPERATURES AND THE FREEZING RAIN. THIS BEING ONE OF THE
FIRST MODEL RUNS TO INDICATE THIS...HAVE USED A BLEND OF THE MODEL
CONSENSUS AND THE PREVIOUS FORECAST FOR THE SURFACE TEMPERATURES.
OTHERWISE...SUNDAY IS EXPECTED TO BE THE WARMEST DAY OF THE FORECAST
WITH TEMPERATURES IN THE 50S SURGING NORTHWARD TO THE MASS PIKE.
THE REST OF MONDAY THROUGH CHRISTMAS DAY...THE ARCTIC FRONT FINALLY
MOVES THROUGH SOUTHERN NEW ENGLAND MONDAY. COLD HIGH PRESSURE
BUILDS IN BEHIND THE FRONT WITH SUBSTANTIALLY COLDER TEMPERATURES
EXPECTED CHRISTMAS EVE AND DAY.
&&
.AVIATION /12Z THURSDAY THROUGH MONDAY/...
FORECASTER CONFIDENCE LEVELS...
LOW...LESS THAN 30 PERCENT.
MODERATE...30 TO 60 PERCENT.
HIGH...GREATER THAN 60 PERCENT.
NEAR TERM /THROUGH FRIDAY/...
HIGH CONFIDENCE IN VFR CONDITIONS FOR MUCH OF THE REGION TODAY.
MODERATE CONFIDENCE VFR TONIGHT...WITH THE POTENTIAL FOR SOME
MVFR CONDITIONS IN SHOWERS. ISOLATED POCKETS OF ICING POSSIBLE
NORTH OF KLWM-KFIT-KORE-KAQW. GUSTY SW WIND GUSTS UP TO 30 KT
DEVELOPING AT KACK BY LATE MORNING.
KBOS TAF...HIGH CONFIDENCE IN TAF.
KBDL TAF...HIGH CONFIDENCE IN TAF.
OUTLOOK...FRIDAY NIGHT THROUGH MONDAY...
FRIDAY NIGHT THROUGH SATURDAY...MODERATE CONFIDENCE. MAINLY VFR.
SATURDAY NIGHT THROUGH EARLY MONDAY MORNING...LOW CONFIDENCE.
MVFR/IFR CONDITIONS DEVELOP IN MAINLY RAIN SHOWERS. FREEZING RAIN
IS POSSIBLE MAINLY THROUGH SOUTHERN NEW HAMPSHIRE.
MONDAY AFTERNOON/EVENING/NIGHT...HIGH CONFIDENCE. IMPROVEMENT TO
VFR BEHIND ARCTIC FRONT. WINDS SHIFT FROM SW TO NW.
&&
.MARINE...
FORECASTER CONFIDENCE LEVELS...
LOW...LESS THAN 30 PERCENT.
MODERATE...30 TO 60 PERCENT.
HIGH...GREATER THAN 60 PERCENT.
NEAR TERM /THROUGH FRIDAY/...HIGH CONFIDENCE
ANOTHER PULSE OF STRONG SW WINDS WILL DEVELOP LATER TODAY. NEAR
GALE FORCE GUSTS POSSIBLE OVER THE OUTER SOUTH COASTAL WATERS.
CONFIDENCE IN A PROLONGED PERIOD OF GALE FORCE GUSTS IS MODERATE
AT BEST. WINDS WILL DIMINISH TONIGHT AS PRESSURE GRADIENT
RELAXES. DECIDED TO REPLACE THE GALE WATCH WITH A HIGH END SMALL
CRAFT ADVISORY.
LATEST WNA WAVE HEIGHT GUIDANCE LOOKS SLIGHTLY UNDERDONE. WILL
MAKE SOME TWEAKS IN THE NEAR TERM TO BRING SEAS UP TO LATEST
MARINE REPORTS.
OUTLOOK...FRIDAY NIGHT THROUGH MONDAY...
SOUTHWESTERLY WINDS WITH PERIODS OF GUSTS UP TO 30 KTS PERSIST
THROUGH MUCH OF THE LONG TERM. WINDS SHIFT TO THE NORTHWEST AS AN
ARCTIC FRONT MOVES ACROSS THE WATERS MONDAY. WAVES BUILD AND
DIMINISH AS WAVES OF LOW PRESSURE MOVE ALONG AN ARCTIC FRONT THROUGH
NORTHERN NEW ENGLAND BUT GENERALLY REMAIN ABOVE 5 FEET ON THE OUTER
WATERS AT LEAST. MUCH OF THIS TIME WILL LIKELY NEED SMALL CRAFT
ADVISORIES UP FOR AT LEAST THE OUTER WATERS...BUT OVERALL CONFIDENCE
IS LOW ON TIMING.
&&
.BOX WATCHES/WARNINGS/ADVISORIES...
CT...NONE.
MA...NONE.
NH...NONE.
RI...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL 6 PM EST THIS EVENING FOR
ANZ231>234-251.
SMALL CRAFT ADVISORY UNTIL 5 PM EST THIS AFTERNOON FOR ANZ230-
236.
SMALL CRAFT ADVISORY UNTIL 6 AM EST FRIDAY FOR ANZ235-237.
SMALL CRAFT ADVISORY UNTIL 10 PM EST THIS EVENING FOR ANZ250.
SMALL CRAFT ADVISORY UNTIL 6 PM EST FRIDAY FOR ANZ254>256.
&&
$$
SYNOPSIS...BELK/RLG
NEAR TERM...BELK/RLG
SHORT TERM...BELK
LONG TERM...RLG
AVIATION...BELK/RLG
MARINE...BELK/RLG
AREA FORECAST DISCUSSION
NWS TAUNTON MA
604 AM EST THU DEC 19 2013
.SYNOPSIS...
DRY AND MILDER WEATHER EXPECTED TODAY AS A COLD FRONT STALLS TO
OUR NORTH. THIS STALLED FRONT WILL RESULT IN PERIODS OF UNSETTLED
WEATHER FRI NIGHT THROUGH EARLY MON. DRIER AND COOLER WEATHER
ARRIVES EARLY NEXT WEEK.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
415 AM UPDATE...MADE SOME TWEAKS TO SKY COVER BASED ON OBSERVED
TRENDS. TWEAKED TEMPERATURES BASED ON THE CLOUDS ALREADY IN
PLACE...AS MOST LOCATIONS INDICATING A REBOUND FROM THEIR
RESPECTIVE MIN TEMPERATURES AS THE CLOUDS ARRIVE.
FOR THE REST OF TODAY...EXPECTING A DRY DAY WITH A HIGH PRESSURE
LOCATED ALONG THE SOUTHEAST USA COAST. THIS WILL RESULT IN A WEST
TO SOUTHWEST FLOW TODAY.
3.9 MICRON SATELLITE IMAGERY SHOWING ABUNDANT LOW-LEVEL MOISTURE
STREAMING EAST FROM THE GREAT LAKES THIS MORNING. THESE CLOUDS
HAVE SINCE COVERED MOST OF SOUTHERN NEW ENGLAND. WEST FLOW...
ALBEIT RELATIVELY LIGHT...THIS MORNING WILL INDUCE SOME
DOWNSLOPING. THUS THINKING THERE SHOULD BE MORE SUN THAN CLOUDS
TODAY...ONCE THE CURRENT CLOUDS IN OUR REGION MOVE EAST. THE
LATEST VERSION OF THE RAP SEEMED TO BE HANDLING THIS SITUATION
WELL...SO RELIED ON IT FOR TIMING.
IT WILL BE A LITTLE WARMER TODAY THAN YESTERDAY WITH THE SUNSHINE
AND WEST TO SOUTHWEST WINDS.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH 6 PM FRIDAY/...
A FRONTAL BOUNDARY WILL SLOWLY MOVE SOUTH THROUGH NORTHERN NEW
ENGLAND TONIGHT. THERE IS STILL SOME QUESTION AS TO EXACTLY HOW
MUCH PROGRESS IT WILL MAKE IN OUR DIRECTION. DEEPER MOISTURE STILL
SHOULD REMAIN NORTH OF OUR REGION FOR MOST OF TONIGHT. SO ONLY
HAVE A CHANCE OF SOME SOME PRECIPITATION VERY LATE TONIGHT INTO
FRIDAY NORTH OF I-90...MAINLY DURING THE DAYTIME FRIDAY.
THE TIMING OF THIS FRONT AND PRECIPITATION WILL BE CRUCIAL FOR
DETERMINING TYPE. THINKING THERE IS A POSSIBILITY FOR SOME LIGHT
ICING ACROSS SOUTHERN NH LATE TONIGHT...BUT IT SHOULD NOT BE VERY
WIDESPREAD. AS SUCH...HOLDING OFF ON ISSUING ANY FREEZING RAIN
ADVISORIES AT THIS TIME. NEXT SHIFT WILL HAVE TO MONITOR THIS
SITUATION. EVENTUALLY ANY PRECIPITATION IN OUR REGION SHOULD
TRANSITION TO ALL RAIN AS TEMPERATURES CONTINUE TO RISE FRIDAY
MORNING. WARMING TREND CONTINUES...WITH HIGHS GENERALLY IN THE 40S
FOR THE FIRST TIME IN SEVERAL DAYS FOR MOST OF THE INTERIOR.
&&
.LONG TERM /FRIDAY NIGHT THROUGH WEDNESDAY/...
* UNSETTLED WEATHER OVER THE WEEKEND
* DRIER...COOLER WEATHER EXPECTED EARLY NEXT WEEK
00Z NAM AND GFS ARE MORE PROGRESSIVE THAN THE ECMWF/UKMET/CANADIAN
WITH WAVES OF LOW PRESSURE MOVING ALONG A COLD FRONT STRETCHED
ACROSS NORTHERN NEW ENGLAND FRIDAY NIGHT AND SATURDAY. WITH THE
SUPPORT OF WPC...AM LEANING AWAY FROM THE NAM/GFS SOLUTION FOR THIS
PERIOD OF THE FORECAST. SUNDAY AND BEYOND...MODELS ARE IN
REMARKABLY GOOD AGREEMENT ON THE GENERAL SYNOPTIC SCALE PATTERN
THROUGH THE LONG TERM. WHILE THE MODELS DO SEEM TO BE NARROWING IN
THEIR RANGE OF SOLUTIONS...THERE IS STILL QUITE A BIT OF UNCERTAINTY
WHEN IT COMES TO THE TEMPERATURE PROFILE SATURDAY NIGHT AND SUNDAY.
THESE TEMPERATURE PROFILES...PARTICULARLY THE SURFACE TEMPERATURES
WILL PLAY A BIG ROLE IN PTYPE. AT THIS POINT...LOOKS LIKE ANY
FROZEN/FREEZING PRECIPITATION WILL BE LIMITED TO SOUTHERN NEW
HAMPSHIRE. THE ARCTIC FRONT MOVES THROUGH SOUTHERN NEW ENGLAND LATE
SUNDAY INTO EARLY MONDAY. THEN COOLER...DRIER WEATHER IS FORECAST
TO PERSIST THROUGH CHRISTMAS DAY.
FRIDAY NIGHT THROUGH SATURDAY...LIGHT PRECIPITATION IS POSSIBLE
ACROSS THE NORTHERN ZONES AS LOW PRESSURE MOVES THROUGH NORTHERN NEW
ENGLAND ALONG THE FRONT. QPF FORECASTS ARE LESS THAN A TENTH OF AN
INCH DURING THIS TIME. HOWEVER...LOOKS THAT SURFACE TEMPERATURES IN
SOUTHERN NEW HAMPSHIRE IN PARTICULAR ARE LIKELY TO BE BELOW
FREEZING. SO THERE IS LIKELY TO BE A PERIOD OF FREEZING RAIN IN
THIS AREA. A VERY MINIMAL TEMPERATURE CHANGE CAN MEAN THE
DIFFERENCE BETWEEN ICING AND REGULAR RAIN SO THIS WILL CONTINUE TO
BE MONITORED.
SATURDAY NIGHT THROUGH MONDAY MORNING...WHILE THE MODELS SEEM TO BE
TIGHTENING UP ON THEIR VARYING SOLUTIONS...THERE REMAINS SOME
UNCERTAINTY IN THE SURFACE TEMPERATURE FORECASTS. IT DOES LOOK LIKE
THERE IS POTENTIAL FOR A PERIOD OF FREEZING RAIN SOMEWHERE NORTH OF
ROUTE 2 IN MASSACHUSETTS AND INTO SOUTHERN NEW HAMPSHIRE. THIS SET
OF MODELS TOOK THE COLDER TEMPERATURES A BIT FARTHER NORTH THAN
PREVIOUS MODELS...KEEPING MOST...IF NOT ALL...OF THE CWA OUT OF THE
COLDER TEMPERATURES AND THE FREEZING RAIN. THIS BEING ONE OF THE
FIRST MODEL RUNS TO INDICATE THIS...HAVE USED A BLEND OF THE MODEL
CONSENSUS AND THE PREVIOUS FORECAST FOR THE SURFACE TEMPERATURES.
OTHERWISE...SUNDAY IS EXPECTED TO BE THE WARMEST DAY OF THE FORECAST
WITH TEMPERATURES IN THE 50S SURGING NORTHWARD TO THE MASS PIKE.
THE REST OF MONDAY THROUGH CHRISTMAS DAY...THE ARCTIC FRONT FINALLY
MOVES THROUGH SOUTHERN NEW ENGLAND MONDAY. COLD HIGH PRESSURE
BUILDS IN BEHIND THE FRONT WITH SUBSTANTIALLY COLDER TEMPERATURES
EXPECTED CHRISTMAS EVE AND DAY.
&&
.AVIATION /11Z THURSDAY THROUGH MONDAY/...
FORECASTER CONFIDENCE LEVELS...
LOW...LESS THAN 30 PERCENT.
MODERATE...30 TO 60 PERCENT.
HIGH...GREATER THAN 60 PERCENT.
NEAR TERM /THROUGH FRIDAY/...
HIGH CONFIDENCE IN VFR CONDITIONS FOR MUCH OF THE REGION TODAY.
MODERATE CONFIDENCE VFR TONIGHT...WITH THE POTENTIAL FOR SOME
MVFR CONDITIONS IN SHOWERS. ISOLATED POCKETS OF ICING POSSIBLE
NORTH OF KLWM-KFIT-KORE-KAQW. GUSTY SW WIND GUSTS UP TO 30 KT
DEVELOPING AT KACK BY LATE MORNING.
KBOS TAF...HIGH CONFIDENCE IN TAF.
KBDL TAF...HIGH CONFIDENCE IN TAF.
OUTLOOK...FRIDAY NIGHT THROUGH MONDAY...
FRIDAY NIGHT THROUGH SATURDAY...MODERATE CONFIDENCE. MAINLY VFR.
SATURDAY NIGHT THROUGH EARLY MONDAY MORNING...LOW CONFIDENCE.
MVFR/IFR CONDITIONS DEVELOP IN MAINLY RAIN SHOWERS. FREEZING RAIN
IS POSSIBLE MAINLY THROUGH SOUTHERN NEW HAMPSHIRE.
MONDAY AFTERNOON/EVENING/NIGHT...HIGH CONFIDENCE. IMPROVEMENT TO
VFR BEHIND ARCTIC FRONT. WINDS SHIFT FROM SW TO NW.
&&
.MARINE...
FORECASTER CONFIDENCE LEVELS...
LOW...LESS THAN 30 PERCENT.
MODERATE...30 TO 60 PERCENT.
HIGH...GREATER THAN 60 PERCENT.
NEAR TERM /THROUGH FRIDAY/...HIGH CONFIDENCE
ANOTHER PULSE OF STRONG SW WINDS WILL DEVELOP LATER TODAY. NEAR
GALE FORCE GUSTS POSSIBLE OVER THE OUTER SOUTH COASTAL WATERS.
CONFIDENCE IN A PROLONGED PERIOD OF GALE FORCE GUSTS IS MODERATE
AT BEST. WINDS WILL DIMINISH TONIGHT AS PRESSURE GRADIENT
RELAXES. DECIDED TO REPLACE THE GALE WATCH WITH A HIGH END SMALL
CRAFT ADVISORY.
LATEST WNA WAVE HEIGHT GUIDANCE LOOKS SLIGHTLY UNDERDONE. WILL
MAKE SOME TWEAKS IN THE NEAR TERM TO BRING SEAS UP TO LATEST
MARINE REPORTS.
OUTLOOK...FRIDAY NIGHT THROUGH MONDAY...
SOUTHWESTERLY WINDS WITH PERIODS OF GUSTS UP TO 30 KTS PERSIST
THROUGH MUCH OF THE LONG TERM. WINDS SHIFT TO THE NORTHWEST AS AN
ARCTIC FRONT MOVES ACROSS THE WATERS MONDAY. WAVES BUILD AND
DIMINISH AS WAVES OF LOW PRESSURE MOVE ALONG AN ARCTIC FRONT THROUGH
NORTHERN NEW ENGLAND BUT GENERALLY REMAIN ABOVE 5 FEET ON THE OUTER
WATERS AT LEAST. MUCH OF THIS TIME WILL LIKELY NEED SMALL CRAFT
ADVISORIES UP FOR AT LEAST THE OUTER WATERS...BUT OVERALL CONFIDENCE
IS LOW ON TIMING.
&&
.BOX WATCHES/WARNINGS/ADVISORIES...
CT...NONE.
MA...NONE.
NH...NONE.
RI...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL 6 PM EST THIS EVENING FOR
ANZ231>234-251.
SMALL CRAFT ADVISORY UNTIL 5 PM EST THIS AFTERNOON FOR ANZ230-
236.
SMALL CRAFT ADVISORY UNTIL 6 AM EST FRIDAY FOR ANZ235-237.
SMALL CRAFT ADVISORY UNTIL 10 PM EST THIS EVENING FOR ANZ250.
SMALL CRAFT ADVISORY UNTIL 6 PM EST FRIDAY FOR ANZ254>256.
&&
$$
SYNOPSIS...BELK/RLG
NEAR TERM...BELK
SHORT TERM...BELK
LONG TERM...RLG
AVIATION...BELK/RLG
MARINE...BELK/RLG
AREA FORECAST DISCUSSION
NWS TAMPA BAY RUSKIN FL
920 AM EST THU DEC 19 2013
...WARMER TEMPERATURES ON THE WAY FOR THE UPCOMING WEEKEND...
.UPDATE...
14Z WATER VAPOR AND H4 RAP ANALYSIS SHOWS AN UPPER LEVEL PATTERN
CHARACTERIZED BY DEEP LONGWAVE TROUGHING DIGGING DOWN THE PACIFIC
COAST AND THROUGH THE INTER-MOUNTAIN WEST...FOLLOWED DOWNSTREAM BY A
MORE ZONAL FLOW PATTERN OVER THE CENTRAL AND EASTERN CONUS. THIS
ZONAL FLOW PATTERN EXTENDS SOUTH TO INCLUDE THE NORTHERN GULF OF
MEXICO COAST AND FLORIDA PENINSULA. WV IMAGERY SHOWS A LARGE SWATH
OF VERY DRY AIR IN THE MID/UPPER LEVELS OF THE TROP COVERING THE
FLORIDA PENINSULA AND THE 18/12Z KTBW SOUNDING PROFILE SHOWS THAT
THIS DRY AIR EXTENDS DOWN INTO THE NEAR SURFACE LAYERS AS WELL. THE
KTBW SOUNDING PROFILE FROM THIS MORNING SHOWS AN IMPRESSIVE PW VALUE
OF ONLY AROUND 0.27". THIS VALUE IS NEARLY 2 STANDARD DEVIATIONS
BELOW CLIMATOLOGY FOR THE MIDDLE OF DECEMBER. WITH ALL THE DRY AIR
OVER OUR HEADS...IT IS LITTLE WONDER THAT WE ARE EXPERIENCING
"CRYSTAL CLEAR" SKIES THIS MORNING AND NEAR 100% OF THE POSSIBLE
SUNSHINE.
AT THE SURFACE...OUR REGIONS RESIDES TO THE SOUTH OF A 1028MB HIGH
PRESSURE RIDGE CENTERED OVER GA/CAROLINAS. THE GRADIENT IS NOT VERY
STRONG RESULTING IN A WEAK EASTERLY FLOW ACROSS THE PENINSULA.
TEMPERATURES WERE QUITE COOL AROUND SUNRISE WITH SOME NEAR FREEZING
TEMPS UP TOWARD LEVY COUNTY...BUT ALREADY SEEING A RAPID RECOVERY OF
THESE TEMPERATURES WITH A COUPLE HOURS OF SUN NOW IN THE BOOKS.
THE REST OF TODAY AND TONIGHT...
A VERY DRY COLUMN ALOFT AND LITTLE IN THE WAY OF MOISTURE ADVECTION
OR SYNOPTIC SUPPORT FOR LIFT WILL KEEP OUR WEATHER FAIR...DRY AND
SEASONABLE. MAY SEE A FEW CUMULUS DEVELOP FOR THE AFTERNOON...BUT
WITH LITTLE MOISTURE TO WORK WITH AND ONLY A LIMITED INCREASE IN LOW
LEVEL ATLANTIC MOISTURE...OUR SKIES SHOULD REMAIN MOSTLY SUNNY
THROUGH THE DAY. TEMPERATURES WILL RISE INTO THE LOWER 70S
NORTH...MID 70S CENTRAL/I-4 CORRIDOR...AND MID/UPPER 70S SOUTH FOR
THE AFTERNOON HOURS. WINDS MAY GO VARIABLE ALONG THE COAST DURING
THE AFTERNOON AS A FEEBLE SEA-BREEZE TRIES TO DEVELOP...BUT THE LACK
OF STRONG INLAND HEATING AND SOME STRONGER FLOW JUST ABOVE THE
SURFACE...SHOULD KEEP ANY CIRCULATION CONFINED TO THE BEACHES OR
POTENTIALLY JUST OFFSHORE.
OVERNIGHT...NOT ANTICIPATING ANY ADDITIONAL FROST CONCERNS FOR THE
NATURE COAST. WILL BE ANOTHER COOL NIGHT...BUT NOT NEARLY AS COOL AS
WEDNESDAY NIGHT INTO EARLY THURSDAY MORNING. COOLEST TEMPERATURES
DOWN POTENTIALLY TO THE LOWER 40S WILL BE FOUND ACROSS THE NORTHERN
NATURE COAST...WITH LOWER TO MIDDLE 50S CENTRAL AND MIDDLE TO UPPER
50S FAR SOUTH.
MORE GENERALLY FAIR WEATHER WITH INCREASINGLY ABOVE NORMAL
TEMPERATURES WILL CONTINUE INTO FRIDAY AND SATURDAY. ENJOY THE REST
OF YOUR THURSDAY!
&&
.AVIATION...
VFR CONDITIONS ARE EXPECTED TO CONTINUE FOR THE NEXT 24 HOURS.
SURFACE HIGH PRESSURE SITUATED OVER THE SOUTHEAST U.S. THIS MORNING
WILL MOVE OFFSHORE THIS AFTERNOON AND TONIGHT. WINDS WILL REMAIN
LIGHT OUT OF THE EAST NORTHEAST...THEN VEERING TO THE SOUTHEAST BY
THIS EVENING AND INTO FRIDAY.
&&
.MARINE...
EASTERLY WINDS TODAY WILL TURN MORE TO THE SOUTHEAST FOR FRIDAY
AND INTO THE WEEKEND. WIND SPEEDS WILL INCREASE SOME ON SATURDAY
AND THEN WILL LIKELY REACH CAUTIONARY OR EVEN ADVISORY LEVELS
SATURDAY NIGHT INTO SUNDAY AS A FRONT APPROACHES THE WATERS.
SPEEDS RELAX SOME SUNDAY INTO MONDAY AND THEN TURN NORTHEASTERLY
BEHIND THE FRONT WITH SPEEDS INCREASING AGAIN ONCE THE FRONT
MOVES THROUGH THE WATERS. HAZARDOUS CONDITIONS LOOK TO CONTINUE
THROUGH AROUND MID-WEEK.
&&
.PRELIMINARY POINT TEMPS/POPS...
TPA 75 59 80 67 / 0 10 10 10
FMY 78 60 84 67 / 0 10 20 10
GIF 76 57 82 64 / 0 10 10 10
SRQ 76 58 81 66 / 0 10 10 10
BKV 75 48 80 60 / 0 10 10 10
SPG 73 62 78 67 / 0 10 10 10
&&
.TBW WATCHES/WARNINGS/ADVISORIES...
FL...NONE.
GULF WATERS...NONE.
&&
$$
UPDATE...MROCZKA
AVIATION...WYNN
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
415 AM CST THU DEC 19 2013
.DISCUSSION...
328 AM CST
TODAY THROUGH TONIGHT...
OVER THE NEXT SEVERAL DAYS WILL FEATURE A METEOROLOGICAL ROLLER
COASTER...WITH A WIDE RANGE OF TEMPERATURES ABOVE/BELOW
FREEZING...PRECIPITATION CHANGING FROM FROZEN TO LIQUID AND BACK TO
FROZEN...MELTING SNOWPACK WITH POTENTIAL FOR ABUNDANT RAINFALL ON
FROZEN GROUND AND CONSIDERABLE ICE ON AREA STREAMS LEADING TO
POSSIBLY HYDRO CONCERNS. TO FURTHER COMPOUND THE HYDRO CONCERNS WILL
BE THAT IF ICE BREAKS UP ON STREAMS IT MAY EASILY BECOME LOCKED BACK
UP AS SUB-FREEZING AIR RETURNS FOR EARLY NEXT WEEK.
MAIN ITEM ON THE AGENDA FOR TODAY...CAN FOG DEVELOP AND HOW WARM
WILL SFC TEMPS BECOME THIS AFTN. A WEAK SFC LOW NORTHEAST OF THE
STRAITS OF MACKINAW CONTINUES TO PUSH EAST WITH A TRAILING FRONTAL
BOUNDARY STRETCHING WEST THROUGH CENTRAL WISC INTO CENTRAL IOWA.
BROAD ANTI-CYCLONIC FLOW OVER THE CANADIAN PRAIRIES IS SEEPING
SOUTH...AND EXPECTED TO SHARPEN THE BAROCLINIC ZONE ALONG THE
STALLED FRONTAL BOUNDARY.
MAIN CONCERNS FOR TODAY WILL REVOLVE AROUND WHEN/IF FOG CAN
DEVELOP...ALONG WITH STEADILY MOISTENING OF THE NEAR SFC ENVIRONMENT
AS ADDTL MOISTURE ADVECTS NORTH FROM A NEARLY +3 SIGMA V-WIND
COMPONENT INTO AN ABNORMALLY HIGH PWAT REGION OF NORTHERN
IL/NORTHWEST IN. SOUNDINGS HAVE STEADILY OVERDONE MOISTURE...AND
PRESENT T/TD DEPRESSIONS IN PLACES REMAIN IN EXCESS OF 5 DEG TO AS
MUCH AS 10 DEG...WHICH PLACES LESS CONFIDENCE ON THE DEVELOPMENT OF
FOG FOR A FEW HOURS. THERE ARE A FEW LOCATIONS THAT HAVE SOME PATCHY
FOG THIS MORNING...HOWEVER THE COVERAGE IS LIKELY GOING TO REMAIN
LOW. THERMAL BOUNDARY EXISTS FROM MOLINE EAST THROUGH
GARY/VALPO...TO THE NORTH TEMPS ARE IN THE TEENS/20S AND SOUTH THEY
ARE IN THE MID/UPR 30S.
GUIDANCE HAS CONSOLIDATED AROUND LATE MORNING WITH THE BEGINNING
TIMEFRAME FOR DRIZZLE/LGT RA...SO HAVE PUSHED BACK TIMING UNTIL
THEN. TEMPS NORTH OF I-88 WILL LIKELY REMAIN IN THE MID 30S TDY
WHILE SOUTH OF THIS LINE TEMPS SHUD WARM TO ARND 40.
THEN FOR TONIGHT IT APPEARS THE SETUP CONTINUES TO FAVOR FREEZING
RAIN...MAINLY FOR AREAS ALONG AND WEST OF LASALLE TO WAUKEGAN. WEAK
LOW WILL LIFT NORTHEAST ALONG THE BAROCLINIC ZONE WITH THE DEEPER
MOISTURE PEELING OFF TO THE NORTHEAST...WHICH WILL LEAVE IN ITS WAKE
A BAGGY ENVIRONMENT. WITH THE LACK OF LIFT...AND TEMPS HOVERING ARND
FREEZING TO JUST BELOW FREEZING...AND THERMAL PROFILES SHOWING A
CONSIDERABLE WARM LAYER...ANY PRECIP WILL LIKELY BE LGT AND FREEZING
RAIN OR FREEZING DRIZZLE. EAST OF THE AFOREMENTIONED LINE SFC TEMPS
SHUD HOLD RIGHT AT FREEZING OR JUST ABOVE...KEEPING PRECIP IN LIQUID
FORM. NONETHELESS WITH THE GROUND STILL FROZEN FROM THE PAST FEW
WEEKS...UNTREATED SURFACES MAY STILL HAVE SOME SLICK SPOTS.
CONFIDENCE IN TEMPS...MEDIUM/HIGH.
CONFIDENCE IN FZRA TONIGHT WEST OF LASALLE TO WAUKEGAN...HIGH.
CONFIDENCE IN AREAS EAST OF THIS LINE SEEING FZRA...MEDIUM.
FRIDAY THROUGH SUNDAY...
THE FORECAST AREA WILL CONTINUE TO BE IN A RATHER MOIST
ENVIRONMENT...WITH LINGERING LLVL/MID-LVL MOISTURE IN THE WAKE OF
THE DEPARTING SFC LOW...THUS FRI MORNING MAY CONTINUE TO SEE SPOTTY
FZRA/FZDZ OR LGT SN FOR THE FAR NW. FURTHER EAST TEMPS WILL LIKELY
REMAIN ABOVE FREEZING AND AGAIN ANY PRECIP WILL BE LGT AND RAIN.
SFC RIDGE ACROSS THE NORTHERN PLAINS/UPPER MIDWEST WILL SAG SOUTH
AND BECOME ORIENTED FROM THE CENTRAL PLAINS NORTHEAST TO WESTERN
LAKE SUPERIOR...PLACING THE CONTINUED BAROCLINIC ZONE SOMEWHERE
ACROSS THE CWFA AND BECOMING ORIENTED FROM SW TO NE PERHAPS FROM
LASALLE IL TO KENOSHA WI. TEMPS WILL REMAIN NEARLY STEADY THROUGHOUT
THE DAY IN THE LOW/MID 30S TO PSBLY ARND 40 ACROSS THE FAR SE CWFA.
FOCUS BEYOND FRI WILL BE ON THE HIGHLY ANTICIPATED MID-LVL VORT
MAX...PROGGED TO SLIDE EAST ACROSS THE SOUTHERN ROCKIES INTO WEST
TEXAS FRI NGT. DOWNSTREAM OF THIS FEATURE THE RIDGE WILL BECOME
PARKED ACROSS THE WESTERN ATLANTIC/SOUTHEAST COAST...ALLOWING A
CONSIDERABLE PLUME OF MOISTURE TO ADVECT NORTH THROUGH THE OZARKS
INTO THE TENN/OHIO VALLEY. GUIDANCE HAS BEEN CONSISTENT OVER THE
PAST FEW DAYS WITH AN ABUNDANCE OF PRECIP THROUGHOUT THIS
REGION...THE UNCERTAINTY IS ON HOW FAR NORTH IT WILL STRETCH.
CYCLOGENESIS CONTINUES TO BE PROGGED OVER CENTRAL TEXAS...AND
QUICKLY LIFT NORTH/NORTHEAST SAT TO FAR SOUTHERN IL BY EARLY SUN
MORNING. MODELS WILL LIKELY CONTINUE TO DEMONSTRATE CORRECTIONS OR A
WOBBLE ON THE PRECISE SFC LOW PATH...LARGELY IN PART FROM THE
PRESENT SNOW COVER/BARE GROUND LINE.
AS FOR P-TYPE SAT/SUN...THIS TOO CONTINUES TO EVOLVE WITH THE LATEST
FORECAST SOLUTIONS. THE EC/GFS HAVE SLIGHTLY DIFFERENT IDEAS ON THE
PATH OF THE SYSTEM...WHICH WILL DICTATE WHERE RAIN AND/OR SNOW WILL
FALL. NOT TO MENTION HOW MUCH OF EACH. AT THIS JUNCTURE HAVE OPTED
TO MAINTAIN THE CURRENT THINKING RATHER THAN FLIP-FLOPPING THE
FORECAST...GIVEN THE UNCERTAINTY THAT REMAINS. SOME COOLING DOES
APPEAR TO TAKE SHAPE FOR THE NORTH/NORTHWEST CWFA SAT...WHICH COULD
KEEP TEMPS SUB-FREEZING OR AT FREEZING THROUGHOUT THE DAY SAT.
850MB LOW IS PROGGED TO LIFT NORTHEAST ACROSS THE CWFA...CURRENTLY
SHAPING UP TO BE ALONG A PONTIAC TO CHICAGO LINE. THIS WOULD LIKELY
DISPLACE THE DEFORMATION ZONE TO THE NORTHWEST ACROSS THE FAR NW
CWFA SAT EVENING/EARLY SUN. THERE HAS ALSO BEEN CONSISTENCY IN A DRY
WEDGE LIFTING NE IN THE WAKE OF THE SFC LOW...WHICH COULD FEATURE A
PERIOD OF DRY WX SUN MORNING FOR THE FAR SE CWFA.
FRONTAL BOUNDARY SWEEPS EAST ACROSS THE FORECAST AREA BY MIDDAY
SUN...WITH FLOW BECOMING UNIFORM FROM THE NORTH/NORTHWEST. 500MB
TROUGH AXIS THEN PUSHES OVER THE REGION...WITH ANY LINGERING PRECIP
FALLING AS LGT SNOW SUN AFTN/EVE SETTING THE STAGE FOR LAKE EFFECT
DOWNSTREAM OF LAKE MICHIGAN.
CONFIDENCE IN TEMPS...MEDIUM/HIGH.
CONFIDENCE IN SNOW REMAINING NW OF LASALLE TO WAUKEGAN THRU SAT
NGT...MEDIUM/HIGH.
MONDAY THROUGH CHRISTMAS DAY...
ENSEMBLES HAVE REMAINED RATHER CONSISTENT WITH A SIMILAR SETUP OF
TWO RIDGES INFLUENCING THE WEATHER PATTERN. ONE BEING PARKED ACROSS
THE EASTERN PACIFIC...THE OTHER OVER THE WESTERN ATLANTIC. THIS
SETUP ALLOWS FOR THE CONTINUED TROUGHING ACROSS THE CENTER OF THE
COUNTY INCLUDING THE GREAT LAKES REGION. HOWEVER BY CHRISTMAS DAY
THESE FEATURES ARE PROGGED TO WEAKEN...WITH MID-LVL FLOW OVER THE
CENTRAL CONUS FLATTENING OUT.
THERE IS SOME INDICATIONS THAT BEYOND CHRISTMAS DAY A HIGH AMPLITUDE
RIDGE WILL BEGIN TO DEVELOP ACROSS FAR WESTERN CANADA...AND COULD
EVENTUALLY DEVELOP A DOWNSTREAM TROUGH YET AGAIN FOR THE GREAT LAKES
REGION LATER NEXT WEEK.
MON/TUE OPERATIONAL SOLUTIONS HAVE A BROAD SFC RIDGE MOVING EAST
ACROSS THE GREAT LAKES REGION AS THE MID-LVL TROUGH AXIS PIVOTS
EAST. THERMAL TROUGH ALOFT WILL LIKELY KEEP TEMPS IN THE TEENS/LOW
20S MON THEN BEGIN TO MODERATE INTO THE 20S BY TUE. WITH THE
AFOREMENTIONED DISCUSSION ON A FLATTENING FLOW...TEMPS MAY RETURN TO
SEASONAL CONDITIONS OR LOW 30S BY CHRISTMAS DAY. MODELS ARE
INDICATING A WEAK MOISTURE STARVED BOUNDARY ARRIVING ACROSS THE
REGION FOR CHRISTMAS DAY...COULD PROVIDE A FEW FLURRIES/LGT SNOW.
CONFIDENCE IN EXTENDED PERIODS...HIGH.
BEACHLER
&&
.HYDROLOGY...
THERE CONTINUES TO BE AN ELEVATED THREAT OF HEAVY RAINFALL AND
FLOODING THIS WEEKEND. FOR ADDITIONAL DETAILS PLEASE REFER TO THE
FLOOD POTENTIAL OUTLOOK (CHIESFLOT) ISSUED THIS AFTERNOON.
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 09Z...
* WINDS BCMG EAST IN THE AFTN...ARND 5 KT AT ORD. AT MDW...WINDS
BECOME SOUTHEAST AND REMAIN LIGHT THROUGH THE PERIOD.
* -DZ IS PSBL IN THE AFTN...WITH -RA EXPECTED IN THE EVENING AND
OVERNIGHT. MVFR VSBY IS EXPECTED WITH -DZ AND -RA.
* IFR CIGS ARRIVE BY MID MORNING AND PERSIST THROUGH THE
PERIOD...WITH THE POSSIBILITY OF LIFR CIGS FROM LATE AFTN ON.
JEE
//DISCUSSION...UPDATED 09Z...
MADE A FEW SIGNIFICANT CHANGES TO THE TAFS. PUSHED BACK LOWER VSBY
AND DRIZZLE TO THIS AFTN. IT IS STILL VERY DRY OUT THERE WHICH IS
WHY FOG AND LOW CIGS HAVE NOT DEVELOPED YET. THE CLOSEST MVFR CIGS
ARE OVER MINNESOTA AND SOUTH DAKOTA. A COLD FRONT WILL SINK SOUTH
AND STALL OUT RIGHT BTWN ORD AND MDW. AS SUCH ADJUSTED WINDS IN
THE TAFS.
PREVIOUS DISCUSSION...06Z...
HIGH PRESSURE IS OVER THE SOUTHERN ATLANTIC COAST WHILE
WEAK LOW PRESSURE IS OVER NORTHERN WISCONSIN. THE LOW WILL WEAKEN
AS IT SHIFTS EAST TODAY...WHILE A COLD FRONT PUSHES SOUTH DOWN THE
LAKE. IN THE NEAR TERM WINDS WILL REMAIN OUT OF THE SW AT 10 KT OR
LESS AS THE PRESSURE GRADIENT WEAKENS. PUSHED BACK REDUCED VSBYS
AND IFR CIGS AS OBSERVATIONS SUGGEST IT IS STILL TOO DRY FOR
EITHER TO FORM IN THE NEAR TERM.
MOISTURE INCREASES THROUGH THIS MORNING WITH DRIZZLE POSSIBLY
FORMING EARLY THIS AFTN ALONG WITH IFR CIGS. IN ADDITION TO THE
MOISTURE...FORCING INCREASES BY THE AFTN. STILL NOT ENTIRELY
CONFIDENT IN THE START TIME.
THE COLD FRONT SINKS SOUTH WITH VARIABLE WINDS EXPECTED AHEAD OF
IT AND THEN WINDS SETTLE OUT OF THE EAST TO NORTHEAST BEHIND THE
FRONT. SPEEDS SHOULD BE 10 KT OR LESS. GUIDANCE ALSO HINTS AT THE
POSSIBILITY OF LIFR CIGS...SO PUT IN FEW004 FOR NOW.
PRECIP SPREADS FROM WEST TO EAST THIS EVENING AHEAD OF THE NEXT
LOW. MAY SEE A PERIOD OF -FZDZ AT RFD...BUT NOT ENTIRELY
CONFIDENT AS SURFACE TEMPS WILL BE RIGHT AROUND FREEZING. THE REST
OF THE AREA...AND EVENTUALLY AT RFD...RAIN IS EXPECTED. BETWEEN
THE ABUNDANCE OF LOW LEVEL MOISTURE AND RAIN...KEPT IFR VSBY AND
IFR TO LIFR CIGS GOING OVERNIGHT.
JEE
//ORD AND MDW CONFIDENCE...UPDATED 09Z...
* HIGH CONFIDENCE IN FORECAST THROUGH 19Z.
* MEDIUM CONFIDENCE IN IFR OR LOWER CIGS OCCURRING...LOW
CONFIDENCE AS TO WHEN THEY ARRIVE AND HOW LOW THEY WILL BE.
* MEDIUM-LOW CONFIDENCE IN OCCURRENCE AND START TIME OF -DZ.
* HIGH CONFIDENCE IN RAIN...MEDIUM CONFIDENCE IN HOW LOW VSBY WILL
BE IN RA.
* MEDIUM CONFIDENCE IN BREAK IN PRECIP EARLY FRIDAY MORNING.
* HIGH CONFIDENCE IN WIND FORECAST.
JEE
//OUTLOOK FOR ORD/MDW FOR 12Z FRIDAY-12Z WEDNESDAY...UPDATED 00Z...
FRIDAY...IFR WITH A CHANCE OF LIGHT RAIN IN THE MORNING...POSSIBLY
CHANGING BRIEFLY TO LIGHT SNOW BEFORE ENDING IN THE MORNING WITH
IMPROVEMENT TO MVFR. MODERATELY STRONG NE WIND DURING THE DAY.
SATURDAY...MVFR DETERIORATING TO IFR WITH INCREASING THREAT OF
RA/SN/IP/ZR. RAIN LIKELY IN THE EVENING...TURNING TO SNOW
OVERNIGHT WITH POSSIBLE LIFR. MODERATELY STRONG NE WIND RETURN
OVERNIGHT.
SUNDAY...SNOW LIKELY. IFR OCCASIONALLY LIFR...IMPROVING TO MVFR
IN THE EVENING. MODERATELY STRONG NE WIND GRADUALLY BACKING TO
NW.
MONDAY...VFR. MODERATELY STRONG NW WIND GRADUALLY DIMINISHING.
TUESDAY...VFR.
TRS
&&
.MARINE...
414 AM CST
LOW PRESSURE IS OVER THE NORTHERN LAKES THIS MORNING AND IT WILL
WEAKEN AS IT SHIFTS EAST. A COLD FRONT PUSHES DOWN THE LAKE TODAY
AND STALLS OVER SOUTHERN LAKE MICHIGAN THIS AFTERNOON AND
OVERNIGHT. WINDS TURN NORTH AND THEN EAST BEHIND THE FRONT AND
INCREASE TO 15 TO 25 KT...WITH SOUTH WINDS 10 TO 20 KT SOUTH OF THE
FRONT. WINDS FINALLY BECOME UNIFORMLY NORTH TO NORTHEAST FRIDAY
MORNING. AS SUCH THE 15 TO 25 KT WINDS MOVE ALONG THE NEARSHORE
WATERS NORTH OF CALUMET HARBOR EARLY FRIDAY MORNING. HAZARDOUS
WAVES ARE ALSO LIKELY FRIDAY AND POSSIBLY INTO FRIDAY NIGHT. A
SMALL CRAFT ADVISORY WILL LIKELY BE NEEDED...BUT DID NOT ISSUE ONE
AT THIS TIME. WINDS AND WAVES WILL BE JUST ON THE CUSP OF SMALL
CRAFT CRITERIA...SO DECIDED TO HOLD OFF JUST A LITTLE LONGER ON THE
NEXT SMALL CRAFT ADVISORY.
THE NEXT LOW PASSES SOUTH OF THE LAKE FRIDAY AND IT WEAKENS AS IT
CONTINUES OFF TO THE NORTHEAST. THE GRADIENT WEAKENS AS DO WINDS
WITH EAST WINDS EXPECTED FRIDAY NIGHT INTO SATURDAY. HIGH PRESSURE
PASSES TO THE NORTHWEST OF THE LAKE SATURDAY...THEN THE NEXT LOW
PUSHES UP THE OHIO RIVER VALLEY SATURDAY NIGHT INTO SUNDAY. WINDS
INCREASE AND BECOME NORTH SUNDAY THEN NORTHWEST SUNDAY NIGHT. A
SMALL CRAFT ADVISORY WILL LIKELY BE NEEDED SATURDAY NIGHT THROUGH
MONDAY FOR HIGH WINDS AND WAVES. OVER THE OPEN WATERS...WINDS TO 30
KT ARE EXPECTED. WINDS TURN WEST BEHIND THE LOW MONDAY NIGHT AND
CONTINUE TO WEAKEN AS HIGH PRESSURE MOVES OVER THE WESTERN LAKES
MONDAY NIGHT. INCREASING SOUTH WINDS ARE EXPECTED TUESDAY BETWEEN
THE DEPARTING LOW AND LOW PRESSURE SYSTEM OVER ONTARIO.
JEE
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...NONE.
&&
$$
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Area Forecast Discussion
National Weather Service Lincoln IL
343 AM CST Thu Dec 19 2013
.DISCUSSION...
ISSUED 311 AM CST Thu Dec 19 2013
High pressure sliding to the southeastern corner of the country as
a cold front slowly approaches the Midwest. A vigorous wave is
digging in over the southwest and translating into more
southwesterly flow over the region. Temperatures slowly increasing
as the airmass modifies with persistent moisture and warm air
advection. Cold front on the way to move through the area late
tonight and tomorrow morning...eventually stalling invof the Ohio
River Valley. Initial fropa less of an issue, with predominantly
rain for ILX. However, the front will provide a focus for precip
in the southeast...and a path to follow for the next wave ejecting
out of the southwest. Models have been very inconsistent with
track and thermodynamics...and are starting to waiver in the
strength overall. That being said, the trend to a more northerly
track is reflected in the forecast.
SHORT TERM...Today and Tonight...
Warmer as southerly winds usher in temps into the 40s. Overnight
expected to remain mostly above freezing as well. Pops return to
the forecast late this afternoon in the extreme NW as rain makes
its way into Central Illinois. Rain chances continue through the
overnight with the front as the winds slowly shift to
northwesterly behind the front and cooler air filters in. Cold air
not moving in very quickly however as the boundary is relatively
weak/the thermal gradient is less significant. For now, the
initial front is dominated by rain. Problems creep in after
midnight tomorrow night as temperatures finally drop and the
precip changes over to freezing rain for the northern half of the
state.
LONG TERM...Saturday through Wednesday...
Models still a problem, lacking continuity and consistency. Trend
to the north is pronounced enough to be reflected however. This
same trend broadens the developing warm sector and reduces the
coldest air. Ice/freezing rain confined mostly to NW of the
Illinois River Valley for Saturday morning, though a transition to
liquid will likely fall between the valley and the I-55 corridor.
Freezing rain in the NW and rain in the SE will continue through
the afternoon and evening before making the transition over to
snow for after midnight and Sunday. All this precip type/wintry
mix determination a low confidence forecast and likely to shift
with subsequent model runs. However, confidence is increasing on
the prolonged and heavy rain event setting up btwn I-70 corridor
and the Ohio River Valley. 2-3 inches of rainfall from Friday
night through Sunday morning will result in an increased flood
risk, particularly with partially frozen ground...already
saturated from recent snowmelt. Flood watch issued with the
forecast from Christian County to Vermilion County and points SE.
Monday bitterly cold on the back side of this system with highs in
the teens... and Monday night sinking into the single digits with light
winds and very little cloud cover. Remains of the forecast left to
the AllBlend for temps, and dry as high pressure returns to the
Midwest until the next systems arrival late Wednesday.
HJS
&&
.AVIATION...
ISSUED 1110 PM CST Wed Dec 18 2013
Little change from earlier thinking this evening, the main
challenge will be timing of the IFR/LIFR cigs and vsbys into
the forecast area on Thursday. Tight pressure gradient over
the state this evening resulted in rather gusty south winds.
The surface winds are expected to diminish some during the
early morning hours, however, the latest short term forecasts
suggest the LLWS in the 1500 ft level will continue thru 12z.
A cold front over the northwest half of Iowa will push to the
Mississippi River by dawn Thursday and then slowly edge east
into our area during the day. The persistent southerly winds
will aid in transporting higher moisture northeast over the
colder/snow covered areas of central IL, which will lead to
widespread low cigs and vsbys, especially during the afternoon
and evening. Confidence on the timing of the lower cigs and
vsbys in our area is not that great at this time as most models
have been too aggressive in developing the IFR cigs and vsbys.
However, the HRRR model has been quite consistent in keeping
the low cigs out thru the morning with development taking place
by afternoon from west to east. Will tend to lean more on that
model`s timing at this point.
Surface winds will remain out of the south at 12 to 17 kts into
the early morning hours with a gradual decrease in the sustained
winds by morning. Southerly winds will hold over the area thru
Thursday with speeds of 8 to 13 kts. Forecast soundings indicate
the potential for some light rain or drizzle with the lower cigs
and vsbys Thursday evening.
Smith
&&
.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS PADUCAH KY
1148 PM CST Wed Dec 18 2013
.UPDATE...
ISSUED AT 942 PM CST WED DEC 18 2013
South winds, just off the surface, are increasing over the
region this evening. KVWX VAD Wind profile indicates 45kts at
925mb and 50kts at 850mb as 0318Z. Cannot see surface winds
decreasing substantially overnight, so we may not see much fall
in temperatures. Just updated to increase lows and winds in some
locations. Leaned on the LAMP and RUC data for the update.
The dewpoints have also been fun to account for, with drier than
expected air over the southern Pennyrile, and increasing moisture
in SEMO. The HRRR seems to have the best handle on the dry air,
but it is likely too aggressive in moistening the southwest. Tried
to just blend it in with the existing forecast to at least head in
the right direction with the trends.
&&
.SHORT TERM...(This Evening through Thursday)
ISSUED AT 152 PM CST WED DEC 18 2013
Southerly winds will keep temperatures up above freezing for most
locations overnight for the first time in a long time. Even though
we will have nearly the lowest sun angle of the year...the snow
field retreats and southerly winds combine to push temps to near 60
across southern portions of the heartland Thursday. High pressure
will gradually be forced off the southeast coast as the upper level
trough digs southeast before ejecting northeast into the heartland.
Otherwise very few changes to the short term.
.LONG TERM...(Thursday Night through Wednesday)
ISSUED AT 152 PM CST WED DEC 18 20131
Will be warm sector Thursday night and most of Friday. Scattered
shower activity expected as the atmosphere moistens up and
impulses move SW/NE across the area. Not much organization wise
given no boundaries to focus on. Mainly mid level support and WAA.
Best chance of thunder Friday should be across the SRN 1/3 of the
area. Late Friday afternoon a strong cold front will enter into
our NW CWFA. The front is forecast to push southeast into our area
and then stall. Showers/TSRA should increase after midnight Friday
night with convective focus near and just north of the boundary.
The boundary should stall somewhere near the Ohio River. The front
will then lift back north as a warm front Saturday as the upper
flow backs and surface low pressure forms along the front, ending
up over west AR by 00z Sun ahead of a strong H5 moving east along
the US/Mexico border into the srn Plains. The convection/locally heavy
rains should pick up Saturday. The axis may shift slowly northwest
with time, in line with the movement of the front.
Saturday night, the front should park across se MO into srn IL
with areas south into west KY (including sw IN) warm sector. Again
with respect to greatest QPF we are leaning away from the GFS as
the axis seems too far east into the warm sector, whereas the
ECMWF focuses the best QPF more in line with strong 700mb
transport and 850mb speed convergence, which is more to the west
and closer to the surface boundary. WPC continues to lean toward this
solution as well. Having said that, would not be surprised to see
an adjustment back to the east just a tad, but not as far as the
GFS. All said and done, main focus Friday night through early
Sunday, 1 1/2-3" rain amounts west KY, increasing to 3-4" or so
from about the Ohio River on north and west. Higher amounts
possible. Will continue with our Hydrologic Outlook product, to
detail the prospects of flooding. As we`ve stated since Monday,
precipitable water values are forecast to remain very high,
1.5-1.75". The potential precip efficiency is cause for concern
given the saturated ground conditions. Concern is mainly small
creeks, ditches, roads that typically flood. Could be a lot of
standing water in fields, etc.
Confidence continues to increase there may be severe storms,
primarily Saturday night, and especially SE of a Poplar Bluff
Missouri, to Evansville Indiana line. This is when we see a notable
increase in forecast winds, from 65-70kts around 850mb up to 85-95
kts 700-500mb, and veering. This coupled with a period of surface
based instability Saturday night in the warm sector, means we could
see some quasi linear segments form and possibly produce damaging
wind gusts and perhaps the typical brief spin up tornado or two we
typically see with a QLCS setup.
Front will blast through Sunday, with precip chances lowering
rapidly from west to east. Temperatures will fall through the day.
Sunday night, mainly dry, though cannot rule out entirely very
light snow or flurries until the mid level wave passes to our
east.
Monday through Christmas day will be dry and seasonably chilly as
strong high pressure builds across the region.
&&
.AVIATION...
ISSUED AT 1148 PM CST WED DEC 18 2013
A change was made for the last six (6) hour of the TAF forecast.
The addition of showers and MVFR ceilings at KCGI/KPAH with the
approaching weather system.
&&
.PAH WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
MO...NONE.
IN...NONE.
KY...NONE.
&&
$$
UPDATE...DRS
SHORT TERM...KH
LONG TERM...CN
AVIATION...Smith
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
641 AM EST THU DEC 19 2013
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 452 AM EST THU DEC 19 2013
A 1005MB LOW PRESSURE OVER EASTERN LAKE SUPERIOR CONTINUES TO
QUICKLY SLIDE EAST THIS MORNING...AS AN ASSOCIATED 925/850MB TROUGH
EXITS THE UPPER GREAT LAKES REGION. THIS QUICK DEPARTURE HAS LED TO
WINDS TURNING TO THE NORTHWEST OVER THE WESTERN LAKE AND AN AREA OF
MVFR CLOUDS (PICKED UP WELL IN THE RH FIELDS OF THE RAP ANALYSIS)
DROPPING SOUTHEAST ACROSS WESTERN AND NORTH CENTRAL UPPER MICHIGAN.
CEILINGS HAVE BEEN LOWERING FAIRLY STEADILY AT KCMX OVER THE LAST
COUPLE OF HOURS AND WITH THE RAP INDICATING 925MB TEMPS FALLING TO
-10C OVER WESTERN LAKE SUPERIOR...HAVE BEEN SEEING INDICATIONS ON
SATELLITE THAT LAKE EFFECT CLOUDS HAVE BEEN DEVELOPING. HAVEN/T
SEEN ANY PRECIPITATION NOTED AT CMX OR ON WEBCAMS OVER THE
KEWEENAW...BUT WOULD EXPECT LIGHT SNOW OR FREEZING DRIZZLE TO START
SHORTLY.
FOR TODAY...WITH THE LOW SLIDING EAST EARLY THIS MORNING AND THE
MAIN SHORTWAVE TO THE NORTHWEST OF LAKE SUPERIOR JUST BRUSHING THE
NORTHERN PART OF THE LAKE...THERE APPEARS TO BE LITTLE SYNOPTIC
FORCING ACROSS THE AREA FOR MUCH OF THE DAY. OTHER THAN THE
POTENTIAL FOR A BRIEF STRONGER SHOWERS MOVING ACROSS EASTERN LAKE
SUPERIOR WITH THE FRONT AND WIND SHIFT TO THE NORTHWEST.
OTHERWISE...THE COLDER AIR DROPPING SOUTHEAST ACROSS LAKE SUPERIOR
(925MB TEMPS FALLING TO -13C BY 00Z FRIDAY) WILL LEAD TO AN INCREASE
IN LIGHT LAKE EFFECT PRECIPITATION THIS MORNING. WITH A HIGH
PRESSURE RIDGE LOCATED JUST TO THE NORTH OF LAKE SUPERIOR TODAY
WILL LEAD TO WINDS VEERING TO THE NORTH-NORTHEAST THROUGH THE DAY.
THIS ANTI-CYCLONIC FLOW ACROSS THE LAKE WON/T BE TOO FAVORABLE FOR
LAKE EFFECT...WHICH WILL COMBINE WITH THE STRONG POCKET OF DRY
AIR ABOVE 850MB (INVERSION HEIGHTS AROUND 4KFT) ASSOCIATED WITH THE
HIGH TO KEEP ANY PRECIPITATION LIGHT. THERE IS SOME CONCERN ON SOME
FREEZING DRIZZLE MIXING WITH THE SNOW FOR THE FIRST PART OF THE
MORNING NEAR LAKE SUPERIOR AND HAVE TRIED TO FOLLOW THE TIMING OF
THE 925MB AROUND -9/-10C TO MARK THE TRANSITION TO ALL SNOW THIS
MORNING. AS FOR AMOUNTS...THINK A DUSTING TO AN INCH SEEMS
REASONABLE...WITH THE MOST IN THE FAVORED NORTH-NORTHEAST UPSLOPE
LOCATIONS OF NORTH CENTRAL UPPER MICHIGAN.
FOR TONIGHT...A QUICK MOVING DISTURBANCE WILL MOVE ACROSS UPPER
MICHIGAN IN THE WESTERLY FLOW ALOFT. IN ADDITIONS TO THE
SHORTWAVE...THE UPPER GREAT LAKES REGION WILL BE UNDER THE
FAVORABLE RIGHT REAR OF A 160KT UPPER JET AND PROVIDE DECENT
SUPPORT ALOFT FOR A SWATH OF SNOW TO MOVE ACROSS THE CWA. AT THE
SURFACE...A WEAK INVERTED TROUGH DOES LOOK TO DEVELOP OVER CENTRAL
UPPER MICHIGAN...WITH WILL HELP KEEP THE LOW LEVEL (950-900MB) FLOW
FOCUSED OVER NORTH CENTRAL UPPER MICHIGAN TO PROVIDE LAKE
ENHANCEMENT. MODELS HAVE BEEN FAIRLY CONSISTENT ON THE SWATH OF
SNOW/QPF MOVING EAST ACROSS THE CWA AROUND MID EVENING AND THEN
QUICKLY DEPARTION ABOUT HALFWAY THROUGH THE OVERNIGHT HOURS.
A GENERAL CONSENSUS IS FOR 0.1-0.15IN OF QPF MOVING ACROSS
CENTRAL/SOUTHERN UPPER MICHIGAN TONIGHT (ONLY 0.05-0.10 OVER THE
KEWEENAW) AND HAVE FOLLOWED THAT FOR THE SYNOPTIC QPF. ONE ITEM TO
NOTE IS THAT THAT DRY POCKET OF AIR BETWEEN 850-700MB WILL NEED TO
BE OVERCOME BEFORE THE SNOW CAN START. FORTUNATELY...THE FLOW IN
THAT LAYER IS FAIRLY LIGHT AND SHOULD ALLOW IT TO QUICKLY MOISTEN.
THEN...WITH THAT FAVORABLE NORTHEAST UPSLOPE AND LAKE ENHANCED
FLOW...ADJUSTED VALUES UP OVER THE HIGHER TERRAIN OF THE NORTH
CENTRAL U.P. FROM THE HURON MOUNTAINS THROUGH NEGAUNEE/GWINN. THE
TRICKY PART IN THE FORECAST COMES FROM PINNING DOWN SNOW RATIOS.
WITH MUCH OF THE BROAD MID LEVEL FGEN FOCUSED WITHIN THE
DGZ...WOULD EXPECT THERE TO BE A 3-4HR PERIOD OF SNOW RATIOS AROUND
20-1 BEFORE A DOWNWARD TREND ONCE THE BETTER FORCING DEPARTS. COBB
OUTPUT AWAY FROM THE LAKE ENHANCEMENT SUPPORTS THAT IDEA AND WITH
THAT DGZ LAYER BEING FAIRLY ISOTHERMAL...HAVE CONTINUED THOSE
RATIOS IN THE FORECAST. IN THE LAKE ENHANCEMENT AREA...THERE ARE
HINTS OF BETTER FORCING BELOW THE DGZ THAT COULD LEAD TO SLIGHTLY
LOWER RATIOS...BUT WONDERING IF THAT MAY BE A TOUCH TOO LOW AS IT
BEING ABOUT 1KFT HIGHER IT WOULD BE IN THE DGZ. THUS...OPTED TO
KEEP THE HIGHER RATIOS IN THE LAKE/TERRAIN ENHANCED AREAS TOO. THIS
LEADS TO A WIDESPREAD 1-3 INCH SNOWFALL FOR MUCH OF UPPER
MICHIGAN...WITH SOME LOCALLY HIGHER AMOUNTS IN THE NORTH CENTRAL.
DEBATED AN ADVISORY FOR MARQUETTE COUNTY FOR AN AVERAGE MORE LIKE
2-4INCHES...BUT OPTED TO DO AN SPS FOR THE ENTIRE CWA INSTEAD.
THERE WERE 2 MAIN REASONS FOR NOT GOING WITH AN ADVISORY.
ONE...SINCE THE MAIN SNOW WILL LIKELY FALL BETWEEN 10PM AND
3AM...THE IMPACTS ON THE POPULATION WILL BE LOWER AND THERE SHOULD
STILL BE ENOUGH TIME TO TREAT THE ROADS BEFORE THE MORNING COMMUTE.
THE SECOND IS A COMBINATION ON UNCERTAINTY WITH SNOW RATIOS AND QPF
AMOUNTS...WHICH BEING OFF BY A COUPLE HUNDREDTHS AT 20 TO 1 COULD
QUICKLY LOWER AMOUNTS. GOING FORECAST WAS FAIRLY SIMILAR TO THE 00Z
NAM AND LOCAL WRF-ARW RUNS...BUT THE 06Z NAM THAT JUST ARRIVED HAS
DROPPED QPF AMOUNTS IN THE ENHANCED AREAS BY 0.07IN. THUS...FELT
HOLDING OFF ON A BORDERLINE ADVISORY WAS WARRANTED AND WILL PASS
CONCERNS TO DAYSHIFT.
.LONG TERM...(FRIDAY THROUGH WEDNESDAY)
ISSUED AT 452 AM EST THU DEC 19 2013
ANY REMAINING MOISTURE AND LIFT RAPIDLY MOVES SOUTH AND EAST ON
FRIDAY MORNING AS A WEAK RIDGE AXIS BUILDS ACROSS LAKE SUPERIOR.
THIS SHOULD ALLOW ANY SNOW SHOWERS OFF THE LAKE TO END QUICKLY IN
THE MORNING. THERE IS A HINT OF LINGERING DEEP MOISTURE ACROSS FAR
SOUTHERN UPPER MI FRI IN THE DEFORMATION ZONE...WITH THE NAM AND
ECMWF SHOWING WEAK MID-LEVEL Q-VECTOR CONVERGENCE THROUGH THE DAY.
HOWEVER...WITH LACK OF SIGNIFICANT LOW LEVEL LIFT AND FAIRLY STRONG
CONFLUENCE ALOFT...WILL LIMIT ANY POPS TO JUST SLIGHT CHANCE ON
FRIDAY ACROSS THE FAR SOUTH.
ON FRIDAY NIGHT INTO SATURDAY...ANOTHER WEAK UPPER TROUGH ROTATES
THROUGH THE AREA. WITH REMAINING MOISTURE ACROSS THE FAR SOUTH FRI
NIGHT...WILL MAINTAIN LOW CHANCE POPS MAINLY IN MENOMINEE COUNTY BUT
AGAIN THE LIFT IS MINIMAL AT BEST. THE NAM SEEMS TO BE AN OUTLIER IN
DEVELOPING A WEAK AREA OF LOW PRESSURE ALONG THE FRONT OVER LAKE
SUPERIOR AND KEEPING IT NEARLY STATIONARY THROUGH SATURDAY BEFORE
MERGING WITH THE DEVELOPING LOW OVER THE SOUTHERN PLAINS SATURDAY
NIGHT. IN FACT...THE NAM ACTUALLY SHOWS ON LAKE MICHIGAN LAKE EFFECT
DEVELOPING IN SCHOOLCRAFT AND DELTA COUNTIES SATURDAY DUE TO THE
SOUTHERLY FLOW AHEAD OF THE LOW. MEANWHILE...THE ECMWF AND THE GFS
SUGGEST A WEAK OPEN WAVE AT BEST WITH MUCH LESS MOISTURE AND LITTLE
IF ANY QPF ON SATURDAY. GIVEN THE WEAK DYNAMICS AT BEST AND THAT THE
NAM IS THE OUTLIER...WILL GENERALLY FOLLOW THE ECMWF SOLUTION AND
KEEP LIMIT ANY POPS TO SLIGHT CHANCE FOR SATURDAY.
FOR THE SOUTHERN STREAM SYSTEM SAT NIGHT INTO SUNDAY NIGHT MOVING
THROUGH THE SOUTHERN GREAT LAKES...THE 18/12Z RUNS STARTED TO TREND
NORTH AND WEST WITH THE LOW. THE 19/00Z RUNS HAVE GENERALLY
CONTINUED THIS TREND WITH THE 19/00Z ECMWF SHIFTING EVEN FURTHER
NORTH AND WEST. WITH THE SYSTEM CLOSING OFF OVER THE SOUTHWESTERN
STATES...WOULD EXPECT THAT THE SYSTEM OVERALL WILL EJECT OUT INTO
THE PLAINS A LITTLE SLOWER THAN THE MODELS SUGGEST. THIS WOULD ALLOW
THE NORTHERN STREAM ENERGY TO POTENTIALLY PHASE WITH THE SOUTHERN
STREAM ENERGY FURTHER NORTH AND WEST...CAUSING THE LOW TO ALSO TRACK
A LITTLE FURTHER NORTH/WEST. AS SUCH...HAVE OPTED TO BRING LIKELY
POPS ACROSS THE ENTIRE EAST HALF OF UPPER MICHIGAN ON SUNDAY/SUNDAY
NIGHT AND RAISE POPS TO NEAR CATEGORICAL IN NORTH CENTRAL UPPER MI.
THIS TYPE OF TRACK WOULD ALLOW FOR A SETUP FOR DECENT LAKE
ENHANCEMENT IN THOSE AREAS FAVORED BY NORTHERLY WINDS WITH PLENTY
OFF DEEP MOISTURE AND AT LEAST SOME SYNOPTIC LIFT IN THE DEFORMATION
ZONE. DO NOT WANT TO TOTALLY BUY OFF ON THE LATEST ECMWF YET AS IT
IS STILL BY FAR THE FURTHEST N AND W...BUT THERE CERTAINLY EXISTS A
POSSIBILITY OF PLOWABLE SNOWFALL FOR MUCH OF THE EASTERN HALF /OR
PERHAPS THE ENTIRE CWFA/ SUNDAY...AND PERHAPS A SIGNIFICANT SNOW FOR
THE FAVORABLE LAKE ENHANCED AREAS. BOTTOM LINE THOUGH...THERE IS
STILL A GREAT AMOUNT OF UNCERTAINTY SO STAY TUNED...
OTHERWISE...BEHIND THIS SYSTEM THE WEATHER QUIETS DOWN WITH A BROAD
LONG WAVE TROUGH SETTLING ACROSS NORTH AMERICA. EXPECT SOME LAKE
EFFECT MONDAY AS THE MAIN SHORT WAVE TROUGH PASSES THROUGH WITH
LINGERING MOISTURE AND 850MB TEMPS AROUND -20C. HOWEVER...THE SFC
RIDGE QUICKLY BUILDS IN BY TUE MORNING WHICH SHOULD END ANY LES.
COULD BE QUITE A COLD MORNING ON CHRISTMAS EVE MORNING WITH THE
RIDGE OVERHEAD AND CLEARING SKIES. WILL GO WITH TEMPS WELL BELOW
ZERO FOR MOST INTERIOR LOCATIONS. MAY BE ONE OF THOSE -20F MORNINGS
IN THE NORMALLY COLDER SPOTS IF IT STAYS CLEAR AND CALM. SOME LIGHT
SNOW IS POSSIBLE LATER ON CHRISTMAS EVE INTO CHRISTMAS DAY AS THE
FRONTAL SYSTEM MOVES INTO THE AREA ASSOCIATED WITH A FAIRLY POTENT
LOOKING SHORT WAVE TROUGH...BUT DETAILS ARE TOUGH TO PIN DOWN. TEMPS
IN THE EXTENDED STILL LOOK BELOW NORMAL.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z FRIDAY MORNING)
ISSUED AT 640 AM EST THU DEC 19 2013
A DEPARTING LOW PRESSURE SYSTEM WILL PULL COLDER AIR ACROSS LAKE
SUPERIOR THIS MORNING AND SHOULD LEAD TO THE DEVELOPMENT OF -SHSN
OVER THE NEXT COUPLE OF HOURS. ALTHOUGH THERE HAVE BEEN LIMITED
REPORTS OF SNOW THUS FAR...WOULD EXPECT SOME MVFR VISIBILITY
RESTRICTIONS TO GO WITH THE LOW END MVFR CEILINGS. VEERING WINDS TO
THE NORTH-NORTHEAST THROUGH THE DAY SHOULD DIMINISH SNOW CHANCES
THIS AFTERNOON AT KCMX/KIWD...BUT LEAD TO MORE FAVORABLE CONDITIONS
FOR KSAW.
A DISTURBANCE SLIDING ACROSS UPPER MICHIGAN TONIGHT WILL LEAD TO A
3-5HR BURST OF SNOW AT ALL TAF SITES. THINK KIWD/KSAW WILL SEE THE
WORST CONDITIONS AND TRENDED THEM DOWN TO IFR CEILINGS/VISIBILITIES.
EXPECT IMPROVEMENT IN THE OVERNIGHT HOURS FROM WEST TO
EAST...ALTHOUGH ALL SITES WILL STILL SEE LIGHT SNOW SHOWERS AND MVFR
CONDITIONS.
&&
.MARINE...(FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 452 AM EST THU DEC 19 2013
A LOW DEPARTING EASTERN LAKE SUPERIOR THIS MORNING HAS LED TO AN
INCREASE IN NORTHWEST TO NORTHERLY WINDS ACROSS WESTERN LAKE
SUPERIOR EARLY THIS MORNING AND IT SHOULD SPREAD EAST ACROSS THE
REST OF THE LAKE THROUGH THE MORNING HOURS. ALTHOUGH THERE MAY BE A
FEW GUSTS TO THE 30KT RANGE THIS MORNING...WOULD EXPECT THEM TO
MAINLY BE AROUND 25KTS. A HIGH PRESSURE RIDGE BUILDING OVER
SOUTHERN ONTARIO THIS AFTERNOON WILL WEAKEN THE WINDS THROUGH THE
AFTERNOON AND NIGHT (TO BELOW 20KTS) AS A WEAK LOW TRACKS THROUGH
SOUTHERN LOWER MICHIGAN. THIS HIGH PRESSURE RIDGE WILL CROSS THE
UPPER GREAT LAKES ON FRIDAY AND FRIDAY NIGHT AND LEAD TO CONTINUED
WINDS BELOW 20KTS THROUGH THE FIRST HALF OF THE WEEKEND. A STRONGER
LOW EXITING THE SOUTHERN PLAINS ON SATURDAY AFTERNOON WILL MOVE
THROUGH SOUTHEAST LOWER MICHIGAN ON SUNDAY AND WILL INCREASE
NORTHERLY WINDS ACROSS THE LAKE. AT THIS TIME...EXPECT WINDS TO BE
AROUND 30KTS WITH A FEW GALE FORCE GUSTS TO 35KTS BEFORE DIMINISHING
SUNDAY NIGHT INTO MONDAY.
FINALLY...FREEZING SPRAY WILL BE POSSIBLE DURING THE TIMES OF
STRONGER WINDS...LARGELY TODAY AND LATE SATURDAY NIGHT INTO SUNDAY
NIGHT.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
NONE.
LAKE MICHIGAN...
NONE.
&&
$$
SHORT TERM...SRF
LONG TERM...MRD
AVIATION...SRF
MARINE...SRF
AREA FORECAST DISCUSSION...UPDATED
NWS ABERDEEN SD
937 AM CST THU DEC 19 2013
.UPDATE...
WITH LAST NIGHTS 6Z AND THE NEW 12Z MODELS ZEROING IN ON MY CWA
FOR THE BAND OF SNOW...HAVE DECIDED TO EXPAND THE ADVISORY EAST TO
ENCOMPASS THE ENTIRE CWA. SNOWFALL AMOUNTS OF 2 TO 5 INCHES CAN BE
EXPECTED WITH HIGH SNOW TO LIQUID RATIOS. LUCKILY WINDS WONT BE
TOO BAD BUT STILL BREEZY WHICH COULD LEAD TO SOME BLOWING AND
DRIFTING. WIND CHILLS WILL ALSO BE BOUNCING UP AGAINST CRITERIA BUT
FOR NOW WILL LET THIS BAND OF SNOW GET THROUGH BEFORE WORRYING TOO
MUCH ABOUT WIND CHILLS. UPDATES ALREADY ISSUED.
&&
.PREVIOUS DISCUSSION...
.SHORT TERM...TODAY THROUGH SATURDAY
MAIN FORECAST CHALLENGE TODAY IS SNOW ACCUMULATIONS ACROSS THE
REGION.
CURRENTLY RADAR SHOWS A VERY THIN BAND OF JET STREAK ENHANCED
SNOW ALONG THE WESTERN AND CENTRAL ND/SD STATE LINE. ONLY
HETTINGER IS REPORTING SNOW WITH SIGNIFICANT VSBY REDUCTIONS BUT
WITH FEW OTHER OBS SITES IN THE BAND WILL GIVE A BEST GUESS THAT
THERE HAS TO BE AT LEAST SOME LIGHT SNOW STRETCHING EAST TOWARD
EUREKA. MODEL GUIDANCE OVERALL SHOWS A SIMILAR PICTURE...AT LEAST
ON THE BROAD SCALE. HOWEVER RECENT HI-RES MODEL RUNS DIFFER
GREATLY IN THE DETAILS. THE HRRR IS VERY SLOW TO PROGRESS ANY
PRECIP ACROSS THE SOUTHERN COUNTIES...KEEPING EVEN PIERRE DRY
UNTIL 18Z. STUCK PRETTY CLOSE TO THE LOCAL 4KM FOR HOURLY POPS.
BUT EVEN THIS SOLUTION IS TRICKY BECAUSE IT BRINGS SIGNIFICANTLY
DRIER AIR INTO THE NORTHEASTERN CWA...KEEPING AREAS ALONG HWY 12
AND NORTH PRECIP FREE EAST OF BROWN COUNTY. WHEREAS 00Z RUNS OF
THE ECMWF/GFS/NAM ARE HITTING THE NORTHERN CWA HARDER THAN IN
PREVIOUS RUNS.
SO PLACEMENT OF THE MAIN FIELD OF QPF HAS LOW FORECASTER
CONFIDENCE TODAY. TO COMPOUND THE CHALLENGE SOME MODELS HAVE THE
SFC HIGH DROPPING IN A LITTLE MORE QUICKLY AND IN DIFFERENT AREAS
OF THE CWA WHICH WILL AFFECT WIND SPEEDS AND SNOW RATIOS. STUCK
WITH A 15:1 RATIO AND SOME AREAS OF BLOWING SNOW...BUT IF THE
WINDS REALLY DIE DOWN THAT COULD MEAN RATIOS CLOSER TO 20:1 AND
LESS OF A BLOWING SNOW CONCERN. CURRENTLY HAVE STORM TOTAL SNOW
AMOUNTS OF 2 TO 4 INCHES WITH HIGHEST AMOUNTS NEAR THAT JET STREAK
ON THE ND/SD BORDER AND WEST OF THE MISSOURI RIVER.
AS THE ARCTIC FRONT MOVES FROM NORTH TO SOUTH TODAY TEMPS WILL
REMAIN STEADY OR FALL THROUGH THE DAY. THEN THE COLD AIR SETTLES
IN THROUGH THE REMAINDER OF THE PERIOD.
.LONG TERM...SATURDAY NIGHT THROUGH WEDNESDAY
THE MODELS AND GFS ENSEMBLES AGREE WELL THROUGH THE LONG TERM WITH
KEEPING THE REGION ON THE COLDER SIDE OF NORMAL. THE UPPER LEVEL
FLOW OVER THE REGION REMAINS FROM THE NORTHWEST THROUGH THE LONG
TERM WITH SHORT WAVE TROUGHS/CLIPPER SYSTEMS DROPPING ACROSS THE
REGION. ONE OR MORE OF THESE SYSTEMS MAY END UP BEING MORE
SIGNIFICANT AS FAR AS BRINGING SOME ACCUMULATING SNOWFALL AND
STRONG WINDS BUT TOO DIFFICULT TO SINGLE OUT AT THIS TIME. HAVE
THE LONG TERM BASICALLY DRY FOR NOW UNTIL THERE IS BETTER MODEL
AGREEMENT WITH THESE CLIPPER SYSTEMS. AT THIS TIME...THE EC WAS
SHOWING A COUPLE CLIPPERS MOVING ACROSS FOR EARLY THROUGH MID WEEK
THAT MAY BRING SOME LIGHT SNOW AND STRONG WINDS. HAVE IN SLIGHT
CHANCES OF LIGHT SNOW ACROSS THE NORTHEAST CWA FOR THE FIRST
CLIPPER SYSTEM ON MONDAY NIGHT. OTHERWISE...MUCH BELOW NORMAL
TEMPERATURES WILL CONTINUE WITH MAYBE SOME MODERATION CLOSER TO
NORMAL BY TUESDAY AND WEDNESDAY. THE ADDITIONAL SNOWFALL TODAY AND
THIS EVENING WILL HAVE A BIG INFLUENCE ON THE TEMPERATURES IN THE
LONG TERM AS ARCTIC AIR MASSES MOVE ACROSS THE REGION. SATURDAY
NIGHT AND SUNDAY NIGHT ARE EXPECTED TO BE IN THE SINGLE DIGITS AND
TEENS BELOW ZERO. HIGHS ON SUNDAY AND MONDAY WILL BE MAINLY IN THE
SINGLE DIGITS EITHER SIDE OF ZERO. TUESDAY AND WEDNESDAY AT THIS
TIME ARE EXPECTED TO BE BACK IN THE UPPER TEENS AND 20S. THIS MAY
END UP CHANGING AS THE MODELS EVOLVE.
&&
.AVIATION...
12Z TAFS FOR THE KABR...KATY...KPIR AND KMBG TERMINALS
CEILINGS WILL FALL AND LIGHT SNOW WILL DEVELOP AT ALL TERMINALS
TODAY AS UPPER LEVEL DIVERGENCE SPREADS OVER THE REGION. THE
CEILINGS AND VISIBILITIES WILL FALL TO IFR/MVFR AS THE LIGHT SNOW
DEVELOPS THROUGHOUT THE MORNING AND AFTERNOON. VISIBILITIES COULD
FALL TO 3/4SM OR LESS AT TIMES. ALSO...WITH BLUSTERY NORTH TO
NORTHEAST WINDS SOME BLOWING SNOW IS EXPECTED. EXPECT THE LIGHT
SNOW TO DIMINISH INTO THE EVENING HOURS AND END OVERNIGHT WITH
CEILINGS REMAINING MVFR ALONG WITH DECREASING WINDS.
&&
.ABR WATCHES/WARNINGS/ADVISORIES...
SD...WINTER WEATHER ADVISORY UNTIL 9 PM CST /8 PM MST/ THIS EVENING
FOR BUFFALO-CAMPBELL-CORSON-DEWEY-EDMUNDS-FAULK-HAND-HUGHES-
HYDE-JONES-LYMAN-MCPHERSON-POTTER-STANLEY-SULLY-WALWORTH.
WINTER WEATHER ADVISORY UNTIL 6 AM CST FRIDAY FOR BROWN-CLARK-
CODINGTON-DAY-DEUEL-GRANT-HAMLIN-MARSHALL-ROBERTS-SPINK.
MN...WINTER WEATHER ADVISORY UNTIL 6 AM CST FRIDAY FOR BIG STONE-
TRAVERSE.
&&
$$
UPDATE...TDK
SHORT TERM...WISE
LONG TERM...MOHR
AVIATION...MOHR
WEATHER.GOV/ABERDEEN
AREA FORECAST DISCUSSION...UPDATED
NWS ABERDEEN SD
603 AM CST THU DEC 19 2013
.UPDATE...
12Z AVIATION DISCUSSION UPDATED BELOW.
&&
.SHORT TERM...TODAY THROUGH SATURDAY
MAIN FORECAST CHALLENGE TODAY IS SNOW ACCUMULATIONS ACROSS THE
REGION.
CURRENTLY RADAR SHOWS A VERY THIN BAND OF JET STREAK ENHANCED
SNOW ALONG THE WESTERN AND CENTRAL ND/SD STATE LINE. ONLY
HETTINGER IS REPORTING SNOW WITH SIGNIFICANT VSBY REDUCTIONS BUT
WITH FEW OTHER OBS SITES IN THE BAND WILL GIVE A BEST GUESS THAT
THERE HAS TO BE AT LEAST SOME LIGHT SNOW STRETCHING EAST TOWARD
EUREKA. MODEL GUIDANCE OVERALL SHOWS A SIMILAR PICTURE...AT LEAST
ON THE BROAD SCALE. HOWEVER RECENT HI-RES MODEL RUNS DIFFER
GREATLY IN THE DETAILS. THE HRRR IS VERY SLOW TO PROGRESS ANY
PRECIP ACROSS THE SOUTHERN COUNTIES...KEEPING EVEN PIERRE DRY
UNTIL 18Z. STUCK PRETTY CLOSE TO THE LOCAL 4KM FOR HOURLY POPS.
BUT EVEN THIS SOLUTION IS TRICKY BECAUSE IT BRINGS SIGNIFICANTLY
DRIER AIR INTO THE NORTHEASTERN CWA...KEEPING AREAS ALONG HWY 12
AND NORTH PRECIP FREE EAST OF BROWN COUNTY. WHEREAS 00Z RUNS OF
THE ECMWF/GFS/NAM ARE HITTING THE NORTHERN CWA HARDER THAN IN
PREVIOUS RUNS.
SO PLACEMENT OF THE MAIN FIELD OF QPF HAS LOW FORECASTER
CONFIDENCE TODAY. TO COMPOUND THE CHALLENGE SOME MODELS HAVE THE
SFC HIGH DROPPING IN A LITTLE MORE QUICKLY AND IN DIFFERENT AREAS
OF THE CWA WHICH WILL AFFECT WIND SPEEDS AND SNOW RATIOS. STUCK
WITH A 15:1 RATIO AND SOME AREAS OF BLOWING SNOW...BUT IF THE
WINDS REALLY DIE DOWN THAT COULD MEAN RATIOS CLOSER TO 20:1 AND
LESS OF A BLOWING SNOW CONCERN. CURRENTLY HAVE STORM TOTAL SNOW
AMOUNTS OF 2 TO 4 INCHES WITH HIGHEST AMOUNTS NEAR THAT JET STREAK
ON THE ND/SD BORDER AND WEST OF THE MISSOURI RIVER.
AS THE ARCTIC FRONT MOVES FROM NORTH TO SOUTH TODAY TEMPS WILL
REMAIN STEADY OR FALL THROUGH THE DAY. THEN THE COLD AIR SETTLES
IN THROUGH THE REMAINDER OF THE PERIOD.
.LONG TERM...SATURDAY NIGHT THROUGH WEDNESDAY
THE MODELS AND GFS ENSEMBLES AGREE WELL THROUGH THE LONG TERM WITH
KEEPING THE REGION ON THE COLDER SIDE OF NORMAL. THE UPPER LEVEL
FLOW OVER THE REGION REMAINS FROM THE NORTHWEST THROUGH THE LONG
TERM WITH SHORT WAVE TROUGHS/CLIPPER SYSTEMS DROPPING ACROSS THE
REGION. ONE OR MORE OF THESE SYSTEMS MAY END UP BEING MORE
SIGNIFICANT AS FAR AS BRINGING SOME ACCUMULATING SNOWFALL AND
STRONG WINDS BUT TOO DIFFICULT TO SINGLE OUT AT THIS TIME. HAVE
THE LONG TERM BASICALLY DRY FOR NOW UNTIL THERE IS BETTER MODEL
AGREEMENT WITH THESE CLIPPER SYSTEMS. AT THIS TIME...THE EC WAS
SHOWING A COUPLE CLIPPERS MOVING ACROSS FOR EARLY THROUGH MID WEEK
THAT MAY BRING SOME LIGHT SNOW AND STRONG WINDS. HAVE IN SLIGHT
CHANCES OF LIGHT SNOW ACROSS THE NORTHEAST CWA FOR THE FIRST
CLIPPER SYSTEM ON MONDAY NIGHT. OTHERWISE...MUCH BELOW NORMAL
TEMPERATURES WILL CONTINUE WITH MAYBE SOME MODERATION CLOSER TO
NORMAL BY TUESDAY AND WEDNESDAY. THE ADDITIONAL SNOWFALL TODAY AND
THIS EVENING WILL HAVE A BIG INFLUENCE ON THE TEMPERATURES IN THE
LONG TERM AS ARCTIC AIR MASSES MOVE ACROSS THE REGION. SATURDAY
NIGHT AND SUNDAY NIGHT ARE EXPECTED TO BE IN THE SINGLE DIGITS AND
TEENS BELOW ZERO. HIGHS ON SUNDAY AND MONDAY WILL BE MAINLY IN THE
SINGLE DIGITS EITHER SIDE OF ZERO. TUESDAY AND WEDNESDAY AT THIS
TIME ARE EXPECTED TO BE BACK IN THE UPPER TEENS AND 20S. THIS MAY
END UP CHANGING AS THE MODELS EVOLVE.
&&
.AVIATION...
12Z TAFS FOR THE KABR...KATY...KPIR AND KMBG TERMINALS
CEILINGS WILL FALL AND LIGHT SNOW WILL DEVELOP AT ALL TERMINALS
TODAY AS UPPER LEVEL DIVERGENCE SPREADS OVER THE REGION. THE
CEILINGS AND VISIBILITIES WILL FALL TO IFR/MVFR AS THE LIGHT SNOW
DEVELOPS THROUGHOUT THE MORNING AND AFTERNOON. VISIBILITIES COULD
FALL TO 3/4SM OR LESS AT TIMES. ALSO...WITH BLUSTERY NORTH TO
NORTHEAST WINDS SOME BLOWING SNOW IS EXPECTED. EXPECT THE LIGHT
SNOW TO DIMINISH INTO THE EVENING HOURS AND END OVERNIGHT WITH
CEILINGS REMAINING MVFR ALONG WITH DECREASING WINDS.
&&
.ABR WATCHES/WARNINGS/ADVISORIES...
SD...WINTER WEATHER ADVISORY UNTIL 7 PM CST /6 PM MST/ THIS EVENING
FOR BUFFALO-CAMPBELL-CORSON-DEWEY-EDMUNDS-FAULK-HAND-HUGHES-
HYDE-JONES-LYMAN-MCPHERSON-POTTER-STANLEY-SULLY-WALWORTH.
MN...NONE.
&&
$$
UPDATE...MOHR
SHORT TERM...WISE
LONG TERM...MOHR
AVIATION...MOHR
WEATHER.GOV/ABERDEEN
AREA FORECAST DISCUSSION
NWS HOUSTON/GALVESTON TX
1003 AM CST THU DEC 19 2013
.UPDATE...
MORNING FORECAST UPDATE.
&&
.DISCUSSION...
GULF MOISTURE CONTINUES TO DEEPEN OVER THE AREA WITH SFC DEWPOINT
TEMPS IN THE 60S PUSH INTO THE COAST AND HOUSTON AREA. REGIONAL
RADAR SHOW ISO SHOWERS ACROSS THE AREA AND EXPECT THIS TREND TO
CONTINUE INTO THE AFTERNOON. WATER VAPOR IMAGERY SHOWS A WEAK
SHORTWAVE TROUGH MOVING ACROSS THE AREA WHICH MAY BE ENHANCING
SOME OF THE ACTIVITY. WAVE IS MOVING OUT OF THE AREA SO MAY SEE
SHOWER ACTIVITY TAPER OFF THIS AFTERNOON. MAIN CHANGE IN FORECAST
FOR TODAY WAS TO GO WITH 20 POPS AND ISO SHRA FOR WX GRIDS.
WILL CONTINUE TO EVALUATE SEVERE WEATHER POTENTIAL FOR SATURDAY.
LOOKS LIKE EARLY 12Z MODEL TRENDS ARE FOR AN EARLIER SCENARIO BY
3-6 HRS. DETAILS OF THE EVENT MAY BE COMING TOGETHER BUT STILL
THINK EVENT WILL HINGE ON THE CAP BREAKING AND AVAILABLE
INSTABILITY.
39
&&
.PREV DISCUSSION... /ISSUED 542 AM CST THU DEC 19 2013/
DISCUSSION...
SEE 12Z AVIATION DISCUSSION.
AVIATION...
MADE A FEW CHANGES TO THE TAFS AS MOISTURE RETURN IS A BIT MORE
AGGRESSIVE. RADAR IS ALREADY SHOWING LIGHT RAIN ALONG THE COAST.
FCST SOUNDINGS SHOW CIGS GRADUALLY LOWERING THROUGH THE DAY AND
THE SOUNDINGS BECOME SATURATED BETWEEN 900 AND 800 MB. SOUNDINGS
ARE STRONGLY CAPPED BUT FEEL STREAMER SHOWERS WILL PERSIST THROUGH
THE AFTN. CIGS SHOULD LOWER FURTHER OVERNIGHT AND LIFR CONDS
POSSIBLE BY FRI MORNING. VERY STRONG WINDS OFF THE SURFACE SHOULD
MIX DOWNWARD TODAY SO WILL MAINTAIN GUSTS THIS AFTN. NAM12 SHOWS
45 KNOTS AT 850 MB THIS AFTN SO MAYBE WINDS NEED TO BE NUDGED
UPWARD. 43
PREV DISCUSSION... /ISSUED 440 AM CST THU DEC 19 2013/
DISCUSSION...
LOW LIGHT SATELLITE SHOWING MOSTLY CLOUDY SKIES ACROSS SOUTHEAST
TEXAS THIS MORNING. RADAR IS ALSO STARTING TO PICK UP VERY LIGHT
RETURNS OVER THE COASTAL WATERS TO THE SOUTHWEST. NAM 12 SHOWING
SOME LIGHT PVA CURRENTLY MOVING OVER THE SOUTHWESTERN AREAS. KCRP
SOUNDING ALSO SHOWS A PRETTY THICK SATURATED LAYER. THE PVA WEDGE
WILL CONTINUE TO PUSH TOWARDS THE NORTHEAST DURING THE DAY TODAY
AND IN COMBINATION WITH THE WAA THINK LIGHT STREAMER SHOWERS AND
DRIZZLE WILL BE POSSIBLE. HIGH RES HRRR AND TEXAS TECH WRF ALSO
SUPPORT THIS. THIS TREND OF LIGHT SHOWERS UNDERNEATH THE CAP WILL
PERSIST TODAY AND FRIDAY AHEAD OF THE NEXT UPPER LEVEL SYSTEM.
AS HAS BEEN ADVERTISED THE LAST COUPLE OF DAYS A SHORTWAVE IS
CURRENTLY DIVING SOUTHWARDS FROM THE PACIFIC NORTHWEST. THIS
ENERGY WILL EVENTUALLY WRAP UP INTO AN UPPER LEVEL LOW OVER THE
BAJA OF CALIFORNIA. THE UPPER LEVEL LOW WILL THEN TRACK EASTWARDS
AND EJECT OFF TOWARDS THE NORTHEAST OVER THE TEXAS PANHANDLE.
MODELS ARE STILL SHOWING THE LOW TO GAIN A NEGATIVE TILT TO IT.
UPPER LEVEL DYNAMICS APPEAR TO BE MORE FAVORABLE AGAIN FOR
SATURDAY AS THE ECMWF... GFS... CANADIAN... AND NAM 12 ALL PUT
SOUTHEAST TEXAS IN THE RRQ. SHEAR VALUES REMAIN IMPRESSIVE. 30 KTS
OR GREATER OF SFC TO 1KM SHEAR (SRH ~220 M2/S2) CAN BE FOUND IN
MOST FORECAST SOUNDINGS WITH MODEST CAPE VALUES. WHAT REMAINS TO
BE IN QUESTION IS HOW MUCH DRY AIR AND CAPPING SOUTHEAST TEXAS
WILL HAVE. ECMWF FORECAST SOUNDINGS ARE BY FAR THE MOST MOIST WITH
PWATS APPROACHING 2.00" IN THE IAH FORECAST SOUNDING SATURDAY
EVENING. THE NAM 12 AND GFS ARE SIMILAR WITH MOISTURE VALUES
AROUND 1.60". BOTH THE GFS AND NAM FORECAST SOUNDINGS DO HAVE A
DRY LAYER AROUND THE 700 MB AREA. AS OF NOW THE AMOUNT OF DRY AIR
DOES NOT APPEAR TO BE TO GREAT FOR STORM FORMATION. FORECAST
SOUNDINGS ALSO ERODE THE CAP SATURDAY AFTERNOON. THIS WOULD IN
GENERAL MAKE SENSE GIVEN THE MID- LEVEL COOLING EXPECTED WITH THE
UPPER LEVEL LOW. WITH THE 850 MB SOUTHWESTERLY FLOW THOUGH THIS
MIGHT BE TOUGH. MODEL QPF FIELDS HAVE ALSO BEEN HINTING AT A
SECONDARY QPF BULLS EYE OUT AHEAD OF A MAIN LINE. THIS IS MOST
LIKELY FROM DISCRETE CELLS IN ASSOCIATION WITH THE WARM CONVEYOR
BELT. GIVEN THE ABOVE STRONG TO SEVERE STORMS CERTAINLY SEEMS
POSSIBLE. THE DISCRETE CELLS OUT AHEAD OF THE MAIN LINE COULD HAVE
SOME ISOLATED TORNADOES WITH WIND DAMAGE. THE MAIN LINE IS
CURRENTLY PROGGED TO MOVE THROUGH LATE SATURDAY EVENING. THE LINE
MIGHT HAVE TROUBLE HOLDING TOGETHER IN THE SOUTHWEST WHERE THE CAP
WILL BE STRONGER BUT WILL WAIT FOR FUTURE MODEL RUNS TO HELP
NARROW THESE FINE DETAILS DOWN. STRONG TO DAMAGING WINDS WITH
EMBEDDED TORNADOES WILL BE POSSIBLE IF STORMS DO END UP GOING
LINEAR. DUE TO THE MENTIONED ABOVE SPC HAS NOW INCLUDED SOUTHEAST
TEXAS IN SLIGHT RISK FOR DAY 3.
BEHIND THIS SYSTEM HIGH PRESSURE WILL MOVE SOUTHWARDS FILTERING
COOLER AIR IN ITS WAKE. MONDAY AND TUESDAY MORNING TEMPERATURES
WILL BE IN THE LOWER TO MID 30S WITH HIGHS IN THE 50S. CHRISTMAS
LOOKS TO BE NEAR NORMAL AS HIGH PRESSURE PULLS OFF TO THE EAST. 23
MARINE...
ONSHORE WINDS WILL CONTINUE TO STRENGTHEN AS LOW PRESSURE
INTENSIFIES OVER THE WESTERN HIGH PLAINS. WARMER AIR MOVING
OVER THE COOLER SHELF WATERS MAY PRODUCE SOME SEA FOG AT TIMES
BUT THE WATER TEMPS ARE WARMING A BIT SO THERE IS SOME UNCERTAINTY
WHEN/IF FOG DEVELOPS. WARMER AIR FLOWING OVER COOLER WATER ALSO TENDS
TO LIMIT MIXING SO HAVE LOWERED WIND SPEEDS OVER THE NEARSHORE WATERS.
A WEAK COLD FRONT WILL STALL OVER NORTH TEXAS ON FRIDAY AND THE
GRADIENT WILL WEAKEN. SLIGHTLY LOWER WIND SPEEDS ARE EXPECTED FRIDAY.
THE RESPITE WILL BE SHORT LIVED AS THE GRADIENT TIGHTENS SIGNIFICANTLY
FRIDAY NIGHT AND SATURDAY AND STRONG ONSHORE WINDS ARE EXPECTED. A
SMALL CRAFT ADVISORY WILL LIKELY BE REQUIRED OVER THE OFFSHORE WATERS.
A COLD FRONT WILL CROSS THE COASTAL WATERS ON SUNDAY WITH STRONG
OFFSHORE WINDS DEVELOPING BY SUNDAY EVENING. STRONG WINDS WILL PERSIST
SUNDAY NIGHT AND MONDAY WITH A SMALL CRAFT ADVISORY LIKELY. 43
&&
.PRELIMINARY POINT TEMPS/POPS...
COLLEGE STATION (CLL) 72 64 76 68 77 / 20 20 30 40 70
HOUSTON (IAH) 73 65 78 68 78 / 20 20 30 30 60
GALVESTON (GLS) 69 63 72 63 74 / 20 20 20 30 40
&&
.HGX WATCHES/WARNINGS/ADVISORIES...
TX...NONE.
GM...SMALL CRAFT SHOULD EXERCISE CAUTION UNTIL 6 PM CST THIS EVENING
FOR THE FOLLOWING ZONES: WATERS FROM FREEPORT TO THE
MATAGORDA SHIP CHANNEL 20 NM TO 60 NM...WATERS FROM
FREEPORT TO THE MATAGORDA SHIP CHANNEL OUT 20 NM...WATERS
FROM HIGH ISLAND TO FREEPORT 20 TO 60 NM.
&&
$$
DISCUSSION...39
AREA FORECAST DISCUSSION
NWS HOUSTON/GALVESTON TX
542 AM CST THU DEC 19 2013
.DISCUSSION...
SEE 12Z AVIATION DISCUSSION.
&&
.AVIATION...
MADE A FEW CHANGES TO THE TAFS AS MOISTURE RETURN IS A BIT MORE
AGGRESSIVE. RADAR IS ALREADY SHOWING LIGHT RAIN ALONG THE COAST.
FCST SOUNDINGS SHOW CIGS GRADUALLY LOWERING THROUGH THE DAY AND
THE SOUNDINGS BECOME SATURATED BETWEEN 900 AND 800 MB. SOUNDINGS
ARE STRONGLY CAPPED BUT FEEL STREAMER SHOWERS WILL PERSIST THROUGH
THE AFTN. CIGS SHOULD LOWER FURTHER OVERNIGHT AND LIFR CONDS
POSSIBLE BY FRI MORNING. VERY STRONG WINDS OFF THE SURFACE SHOULD
MIX DOWNWARD TODAY SO WILL MAINTAIN GUSTS THIS AFTN. NAM12 SHOWS
45 KNOTS AT 850 MB THIS AFTN SO MAYBE WINDS NEED TO BE NUDGED
UPWARD. 43
&&
.PREV DISCUSSION... /ISSUED 440 AM CST THU DEC 19 2013/
DISCUSSION...
LOW LIGHT SATELLITE SHOWING MOSTLY CLOUDY SKIES ACROSS SOUTHEAST
TEXAS THIS MORNING. RADAR IS ALSO STARTING TO PICK UP VERY LIGHT
RETURNS OVER THE COASTAL WATERS TO THE SOUTHWEST. NAM 12 SHOWING
SOME LIGHT PVA CURRENTLY MOVING OVER THE SOUTHWESTERN AREAS. KCRP
SOUNDING ALSO SHOWS A PRETTY THICK SATURATED LAYER. THE PVA WEDGE
WILL CONTINUE TO PUSH TOWARDS THE NORTHEAST DURING THE DAY TODAY
AND IN COMBINATION WITH THE WAA THINK LIGHT STREAMER SHOWERS AND
DRIZZLE WILL BE POSSIBLE. HIGH RES HRRR AND TEXAS TECH WRF ALSO
SUPPORT THIS. THIS TREND OF LIGHT SHOWERS UNDERNEATH THE CAP WILL
PERSIST TODAY AND FRIDAY AHEAD OF THE NEXT UPPER LEVEL SYSTEM.
AS HAS BEEN ADVERTISED THE LAST COUPLE OF DAYS A SHORTWAVE IS
CURRENTLY DIVING SOUTHWARDS FROM THE PACIFIC NORTHWEST. THIS
ENERGY WILL EVENTUALLY WRAP UP INTO AN UPPER LEVEL LOW OVER THE
BAJA OF CALIFORNIA. THE UPPER LEVEL LOW WILL THEN TRACK EASTWARDS
AND EJECT OFF TOWARDS THE NORTHEAST OVER THE TEXAS PANHANDLE.
MODELS ARE STILL SHOWING THE LOW TO GAIN A NEGATIVE TILT TO IT.
UPPER LEVEL DYNAMICS APPEAR TO BE MORE FAVORABLE AGAIN FOR
SATURDAY AS THE ECMWF... GFS... CANADIAN... AND NAM 12 ALL PUT
SOUTHEAST TEXAS IN THE RRQ. SHEAR VALUES REMAIN IMPRESSIVE. 30 KTS
OR GREATER OF SFC TO 1KM SHEAR (SRH ~220 M2/S2) CAN BE FOUND IN
MOST FORECAST SOUNDINGS WITH MODEST CAPE VALUES. WHAT REMAINS TO
BE IN QUESTION IS HOW MUCH DRY AIR AND CAPPING SOUTHEAST TEXAS
WILL HAVE. ECMWF FORECAST SOUNDINGS ARE BY FAR THE MOST MOIST WITH
PWATS APPROACHING 2.00" IN THE IAH FORECAST SOUNDING SATURDAY
EVENING. THE NAM 12 AND GFS ARE SIMILAR WITH MOISTURE VALUES
AROUND 1.60". BOTH THE GFS AND NAM FORECAST SOUNDINGS DO HAVE A
DRY LAYER AROUND THE 700 MB AREA. AS OF NOW THE AMOUNT OF DRY AIR
DOES NOT APPEAR TO BE TO GREAT FOR STORM FORMATION. FORECAST
SOUNDINGS ALSO ERODE THE CAP SATURDAY AFTERNOON. THIS WOULD IN
GENERAL MAKE SENSE GIVEN THE MID- LEVEL COOLING EXPECTED WITH THE
UPPER LEVEL LOW. WITH THE 850 MB SOUTHWESTERLY FLOW THOUGH THIS
MIGHT BE TOUGH. MODEL QPF FIELDS HAVE ALSO BEEN HINTING AT A
SECONDARY QPF BULLS EYE OUT AHEAD OF A MAIN LINE. THIS IS MOST
LIKELY FROM DISCRETE CELLS IN ASSOCIATION WITH THE WARM CONVEYOR
BELT. GIVEN THE ABOVE STRONG TO SEVERE STORMS CERTAINLY SEEMS
POSSIBLE. THE DISCRETE CELLS OUT AHEAD OF THE MAIN LINE COULD HAVE
SOME ISOLATED TORNADOES WITH WIND DAMAGE. THE MAIN LINE IS
CURRENTLY PROGGED TO MOVE THROUGH LATE SATURDAY EVENING. THE LINE
MIGHT HAVE TROUBLE HOLDING TOGETHER IN THE SOUTHWEST WHERE THE CAP
WILL BE STRONGER BUT WILL WAIT FOR FUTURE MODEL RUNS TO HELP
NARROW THESE FINE DETAILS DOWN. STRONG TO DAMAGING WINDS WITH
EMBEDDED TORNADOES WILL BE POSSIBLE IF STORMS DO END UP GOING
LINEAR. DUE TO THE MENTIONED ABOVE SPC HAS NOW INCLUDED SOUTHEAST
TEXAS IN SLIGHT RISK FOR DAY 3.
BEHIND THIS SYSTEM HIGH PRESSURE WILL MOVE SOUTHWARDS FILTERING
COOLER AIR IN ITS WAKE. MONDAY AND TUESDAY MORNING TEMPERATURES
WILL BE IN THE LOWER TO MID 30S WITH HIGHS IN THE 50S. CHRISTMAS
LOOKS TO BE NEAR NORMAL AS HIGH PRESSURE PULLS OFF TO THE EAST. 23
MARINE...
ONSHORE WINDS WILL CONTINUE TO STRENGTHEN AS LOW PRESSURE
INTENSIFIES OVER THE WESTERN HIGH PLAINS. WARMER AIR MOVING
OVER THE COOLER SHELF WATERS MAY PRODUCE SOME SEA FOG AT TIMES
BUT THE WATER TEMPS ARE WARMING A BIT SO THERE IS SOME UNCERTAINTY
WHEN/IF FOG DEVELOPS. WARMER AIR FLOWING OVER COOLER WATER ALSO TENDS
TO LIMIT MIXING SO HAVE LOWERED WIND SPEEDS OVER THE NEARSHORE WATERS.
A WEAK COLD FRONT WILL STALL OVER NORTH TEXAS ON FRIDAY AND THE
GRADIENT WILL WEAKEN. SLIGHTLY LOWER WIND SPEEDS ARE EXPECTED FRIDAY.
THE RESPITE WILL BE SHORT LIVED AS THE GRADIENT TIGHTENS SIGNIFICANTLY
FRIDAY NIGHT AND SATURDAY AND STRONG ONSHORE WINDS ARE EXPECTED. A
SMALL CRAFT ADVISORY WILL LIKELY BE REQUIRED OVER THE OFFSHORE WATERS.
A COLD FRONT WILL CROSS THE COASTAL WATERS ON SUNDAY WITH STRONG
OFFSHORE WINDS DEVELOPING BY SUNDAY EVENING. STRONG WINDS WILL PERSIST
SUNDAY NIGHT AND MONDAY WITH A SMALL CRAFT ADVISORY LIKELY. 43
&&
.PRELIMINARY POINT TEMPS/POPS...
COLLEGE STATION (CLL) 72 64 76 68 77 / 20 20 30 40 70
HOUSTON (IAH) 73 65 78 68 78 / 30 20 30 30 60
GALVESTON (GLS) 69 63 72 63 74 / 20 20 20 30 40
&&
.HGX WATCHES/WARNINGS/ADVISORIES...
TX...NONE.
GM...SMALL CRAFT SHOULD EXERCISE CAUTION THROUGH THIS AFTERNOON FOR
THE FOLLOWING ZONES: WATERS FROM FREEPORT TO THE MATAGORDA
SHIP CHANNEL 20 NM TO 60 NM...WATERS FROM FREEPORT TO THE
MATAGORDA SHIP CHANNEL OUT 20 NM...WATERS FROM HIGH ISLAND
TO FREEPORT 20 TO 60 NM.
&&
$$
DISCUSSION...23
AVIATION/MARINE...43
AREA FORECAST DISCUSSION
NWS HOUSTON/GALVESTON TX
440 AM CST THU DEC 19 2013
.DISCUSSION...
LOW LIGHT SATELLITE SHOWING MOSTLY CLOUDY SKIES ACROSS SOUTHEAST
TEXAS THIS MORNING. RADAR IS ALSO STARTING TO PICK UP VERY LIGHT
RETURNS OVER THE COASTAL WATERS TO THE SOUTHWEST. NAM 12 SHOWING
SOME LIGHT PVA CURRENTLY MOVING OVER THE SOUTHWESTERN AREAS. KCRP
SOUNDING ALSO SHOWS A PRETTY THICK SATURATED LAYER. THE PVA WEDGE
WILL CONTINUE TO PUSH TOWARDS THE NORTHEAST DURING THE DAY TODAY
AND IN COMBINATION WITH THE WAA THINK LIGHT STREAMER SHOWERS AND
DRIZZLE WILL BE POSSIBLE. HIGH RES HRRR AND TEXAS TECH WRF ALSO
SUPPORT THIS. THIS TREND OF LIGHT SHOWERS UNDERNEATH THE CAP WILL
PERSIST TODAY AND FRIDAY AHEAD OF THE NEXT UPPER LEVEL SYSTEM.
AS HAS BEEN ADVERTISED THE LAST COUPLE OF DAYS A SHORTWAVE IS
CURRENTLY DIVING SOUTHWARDS FROM THE PACIFIC NORTHWEST. THIS
ENERGY WILL EVENTUALLY WRAP UP INTO AN UPPER LEVEL LOW OVER THE
BAJA OF CALIFORNIA. THE UPPER LEVEL LOW WILL THEN TRACK EASTWARDS
AND EJECT OFF TOWARDS THE NORTHEAST OVER THE TEXAS PANHANDLE.
MODELS ARE STILL SHOWING THE LOW TO GAIN A NEGATIVE TILT TO IT.
UPPER LEVEL DYNAMICS APPEAR TO BE MORE FAVORABLE AGAIN FOR
SATURDAY AS THE ECMWF... GFS... CANADIAN... AND NAM 12 ALL PUT
SOUTHEAST TEXAS IN THE RRQ. SHEAR VALUES REMAIN IMPRESSIVE. 30 KTS
OR GREATER OF SFC TO 1KM SHEAR (SRH ~220 M2/S2) CAN BE FOUND IN
MOST FORECAST SOUNDINGS WITH MODEST CAPE VALUES. WHAT REMAINS TO
BE IN QUESTION IS HOW MUCH DRY AIR AND CAPPING SOUTHEAST TEXAS
WILL HAVE. ECMWF FORECAST SOUNDINGS ARE BY FAR THE MOST MOIST WITH
PWATS APPROACHING 2.00" IN THE IAH FORECAST SOUNDING SATURDAY
EVENING. THE NAM 12 AND GFS ARE SIMILAR WITH MOISTURE VALUES
AROUND 1.60". BOTH THE GFS AND NAM FORECAST SOUNDINGS DO HAVE A
DRY LAYER AROUND THE 700 MB AREA. AS OF NOW THE AMOUNT OF DRY AIR
DOES NOT APPEAR TO BE TO GREAT FOR STORM FORMATION. FORECAST
SOUNDINGS ALSO ERODE THE CAP SATURDAY AFTERNOON. THIS WOULD IN
GENERAL MAKE SENSE GIVEN THE MID- LEVEL COOLING EXPECTED WITH THE
UPPER LEVEL LOW. WITH THE 850 MB SOUTHWESTERLY FLOW THOUGH THIS
MIGHT BE TOUGH. MODEL QPF FIELDS HAVE ALSO BEEN HINTING AT A
SECONDARY QPF BULLS EYE OUT AHEAD OF A MAIN LINE. THIS IS MOST
LIKELY FROM DISCRETE CELLS IN ASSOCIATION WITH THE WARM CONVEYOR
BELT. GIVEN THE ABOVE STRONG TO SEVERE STORMS CERTAINLY SEEMS
POSSIBLE. THE DISCRETE CELLS OUT AHEAD OF THE MAIN LINE COULD HAVE
SOME ISOLATED TORNADOES WITH WIND DAMAGE. THE MAIN LINE IS
CURRENTLY PROGGED TO MOVE THROUGH LATE SATURDAY EVENING. THE LINE
MIGHT HAVE TROUBLE HOLDING TOGETHER IN THE SOUTHWEST WHERE THE CAP
WILL BE STRONGER BUT WILL WAIT FOR FUTURE MODEL RUNS TO HELP
NARROW THESE FINE DETAILS DOWN. STRONG TO DAMAGING WINDS WITH
EMBEDDED TORNADOES WILL BE POSSIBLE IF STORMS DO END UP GOING
LINEAR. DUE TO THE MENTIONED ABOVE SPC HAS NOW INCLUDED SOUTHEAST
TEXAS IN SLIGHT RISK FOR DAY 3.
BEHIND THIS SYSTEM HIGH PRESSURE WILL MOVE SOUTHWARDS FILTERING
COOLER AIR IN ITS WAKE. MONDAY AND TUESDAY MORNING TEMPERATURES
WILL BE IN THE LOWER TO MID 30S WITH HIGHS IN THE 50S. CHRISTMAS
LOOKS TO BE NEAR NORMAL AS HIGH PRESSURE PULLS OFF TO THE EAST. 23
&&
.MARINE...
ONSHORE WINDS WILL CONTINUE TO STRENGTHEN AS LOW PRESSURE
INTENSIFIES OVER THE WESTERN HIGH PLAINS. WARMER AIR MOVING
OVER THE COOLER SHELF WATERS MAY PRODUCE SOME SEA FOG AT TIMES
BUT THE WATER TEMPS ARE WARMING A BIT SO THERE IS SOME UNCERTAINTY
WHEN/IF FOG DEVELOPS. WARMER AIR FLOWING OVER COOLER WATER ALSO TENDS
TO LIMIT MIXING SO HAVE LOWERED WIND SPEEDS OVER THE NEARSHORE WATERS.
A WEAK COLD FRONT WILL STALL OVER NORTH TEXAS ON FRIDAY AND THE
GRADIENT WILL WEAKEN. SLIGHTLY LOWER WIND SPEEDS ARE EXPECTED FRIDAY.
THE RESPITE WILL BE SHORT LIVED AS THE GRADIENT TIGHTENS SIGNIFICANTLY
FRIDAY NIGHT AND SATURDAY AND STRONG ONSHORE WINDS ARE EXPECTED. A
SMALL CRAFT ADVISORY WILL LIKELY BE REQUIRED OVER THE OFFSHORE WATERS.
A COLD FRONT WILL CROSS THE COASTAL WATERS ON SUNDAY WITH STRONG
OFFSHORE WINDS DEVELOPING BY SUNDAY EVENING. STRONG WINDS WILL PERSIST
SUNDAY NIGHT AND MONDAY WITH A SMALL CRAFT ADVISORY LIKELY. 43
&&
.PRELIMINARY POINT TEMPS/POPS...
COLLEGE STATION (CLL) 72 64 76 68 77 / 20 20 30 40 70
HOUSTON (IAH) 73 65 78 68 78 / 30 20 30 30 60
GALVESTON (GLS) 69 63 72 63 74 / 20 20 20 30 40
&&
.HGX WATCHES/WARNINGS/ADVISORIES...
TX...NONE.
GM...SMALL CRAFT SHOULD EXERCISE CAUTION THROUGH THIS AFTERNOON FOR
THE FOLLOWING ZONES: WATERS FROM FREEPORT TO THE MATAGORDA
SHIP CHANNEL 20 NM TO 60 NM...WATERS FROM FREEPORT TO THE
MATAGORDA SHIP CHANNEL OUT 20 NM...WATERS FROM HIGH ISLAND
TO FREEPORT 20 TO 60 NM.
&&
$$
DISCUSSION...23
AVIATION/MARINE...43
AREA FORECAST DISCUSSION
NWS PHOENIX AZ
945 AM MST THU DEC 19 2013
.SYNOPSIS...
A DEEP LOW PRESSURE SYSTEM WILL APPROACH THE DESERT SOUTHWEST TODAY
LEADING TO LOCALLY BREEZY CONDITIONS AND INCREASING CLOUDS.
PRECIPITATION CHANCES WILL BEGIN LATE THIS AFTERNOON...EXPANDING
THIS EVENING AND OVERNIGHT...THEN TAPERING OFF FROM WEST TO EAST BY
FRIDAY AFTERNOON. A LINGERING CHANCE OF SHOWERS MAY CONTINUE OVER
HIGHER TERRAIN LOCATIONS INTO SATURDAY MORNING. THE SYSTEM WILL ALSO
BRING MUCH COOLER TEMPERATURES...GENERALLY BELOW THE SEASONAL
AVERAGE HEADING INTO THE WEEKEND. EXPECT DRY CONDITIONS WITH A SLOW
WARMING TREND DURING THE FIRST HALF OF NEXT WEEK.
&&
.DISCUSSION...
STILL MOSTLY CLOUD FREE ACROSS THE CWA AS THE POSITIVELY TILTED
UPPER LOW SLIDES SOUTHEASTWARD ALONG THE CALIFORNIA COAST. AT THIS
TIME THE SYSTEM REMAINS FAIRLY MOISTURE STARVED...BUT A PLUME OF
MOISTURE IS BEGINNING TO SHOW UP JUST TO THE SOUTHWEST OF SAN DIEGO
ON WATER VAPOR IMAGERY. AS THE LOW SHIFTS SOUTHWARD THIS
AFTERNOON...MID LEVEL WINDS WILL BACK TO THE SOUTH ACROSS SOUTHERN
ARIZONA ALLOWING FOR MOISTURE ADVECTION INTO THE REGION. LATEST HRRR
MODEL RUN INDICATES SOME SHOWER DEVELOPMENT BY AROUND MID AFTERNOON
ACROSS MARICOPA COUNTY AND OUR FAR WESTERN ZONES. GIVEN THE 20-30
KNOTS LOW LEVEL SOUTHERLY WINDS ALREADY IN PLACE...INCREASING
MOISTURE...AND MODERATE ASCENT SHOWN ON FORECAST ISENTROPIC 300-310K
SURFACES...THE HRRR COULD VERY WELL BE CORRECT IN SHOWING AN EARLIER
SHOWER DEVELOPMENT. SO...HAVE INTRODUCED SOME SLIGHT CHANCE POPS
ACROSS SOUTH-CENTRAL ARIZONA LATE THIS AFTERNOON AND ALSO BUMPED UP
POPS INTO THE LIKELY CATEGORY FOR THIS EVENING. THE STRONGEST
FORCING AND THE BEST UNSTABLE LAPSE RATES WILL OCCUR AS THE LOW
CENTER MOVES ACROSS SOUTHERN ARIZONA APPROXIMATELY BETWEEN 09-18Z
FRIDAY. CONFIDENCE IS GROWING THAT THE MAJORITY OF THE REGION WILL
SEE SOME MEASURABLE RAINFALL FROM THIS EVENT SOMETIME LATE TONIGHT
INTO FRIDAY.
&&
.PREVIOUS DISCUSSION...
EARLY MORNING WV IMAGERY DEPICTS A POTENT UPPER LOW CONTINUING TO
TAKE SHAPE OFF THE NORTHERN CALIFORNIA COAST. QUITE A BIT OF DRYING
IN THE UPPER LEVELS FROM ARIZONA ACROSS THE GULF OF CALIFORNIA AND
WESTWARD OUT INTO THE PACIFIC...BUT THIS SHOULDNT PLAY A
SIGNIFICANT ROLE IN OUR WEATHER ACROSS THE DESERT SOUTHWEST AS THIS
DRYING WILL BE DISPLACED WELL SOUTH OF THE INTERNATIONAL BORDER
LATER THIS AFTERNOON. MEANWHILE...EARLY MORNING TEMPERATURES ARE
GENERALLY IN THE MID 40S AND LOWER 50S AS OF 09Z WITH LIGHT WINDS
AND DECREASING CLOUDS.
IN THE VERY SHORT TERM THROUGH MID MORNING...SURFACE OBS AND GOES
IR/FOG IMAGERY INDICATES SOME AREAS OF FOG AROUND MEXICALI. SURFACE
OBS IN SOUTHEAST CALIFORNIA HAVE NOT REPORTED REDUCED VSBYS BUT
MMML WENT DOWN TO 1/16SM A FEW HOURS AGO AND SATELLITE CLEARLY SHOWS
A FOG BANK HEADING UP TOWARD EL CENTRO. AS THE UPPER LOW CONTINUES
TO GET CLOSER TO THE AREA...WINDS SHOULD PICK UP /ALREADY PICKING UP
AT NJK/ AND THAT MAY BE SUFFICIENT FOR IT TO TRANSITION INTO A
STRATUS DECK. BUT IN THE MEANTIME...I HAVE INTRODUCED PATCHY DENSE
FOG INTO THE GRIDS THROUGH MID MORNING. THE FOG DOES NOT LOOK
WIDESPREAD...NOR DOES IT APPEAR TO BE CAUSING ANY SIGNIFICANT
IMPACTS PER INFO FROM CHP. WILL CONTINUE TO MONITOR OBS AND TRENDS
BUT I DO NOT THINK A DENSE FOG ADVISORY IS NECESSARY AT THIS POINT.
THE BIG STORY OBVIOUSLY IS THE UPPER LOW FORECAST TO DROP THROUGH
SOUTHERN CALIFORNIA AND SOUTHWEST ARIZONA LATER TONIGHT INTO FRIDAY.
FOR THE MOST PART THE FORECAST REMAINS ON TRACK WITH CONDITIONS
GRADUALLY MOISTENING THROUGH THE DAY TODAY...RESULTING IN
INCREASING CLOUDS AND COOLER TEMPERATURES. HOWEVER THERE REMAINS
CONSIDERABLE UNCERTAINTY WHEN THE PRECIP WILL BEGIN ACROSS THE
PHOENIX AREA. GFS/EURO SUGGEST PRECIP DEVELOPING AS EARLY AS
06Z...THE SREF CONTAINS MORE THAN A FEW MEMBERS THAT BRING IN PRECIP
AROUND 21Z THIS AFTERNOON. MEANWHILE THE 00Z AND 06Z NAM SUGGEST
PRECIP WILL REMAIN CONFINED TO WESTERN MARICOPA COUNTY AND POINTS
WEST DUE TO QUITE A BIT OF DRY AIR BEING ENTRAINED INTO THE UPPER
LOW FROM THE EAST. NOT GOING TO GO AS AGGRESSIVE AS THE GFS/EURO
BRINGING IN 70-80 POPS THIS EVENING...BUT I FULLY EXPECT SHOWERS TO
DEVELOP OVERHEAD AFTER MIDNIGHT AND I INCREASED POPS QUITE A BIT
AFTER 06Z. WHILE I DO THINK THERE WILL BE A SHARP EDGE TO THE PRECIP
TONIGHT...I THINK THE PHOENIX METRO SEES A DECENT SHOT OF PRECIP
OVERNIGHT INTO FRIDAY MORNING AS THE LOW ARRIVES AND STRONG
SOUTHERLY 850MB WINDS ALIGN WITH THE AXIS OF 0.6-0.8 INCH PWATS.
MEANWHILE...ALL MODELS HAVE COME IN A BIT WETTER ACROSS SOUTHEAST
CALIFORNIA AND SOUTHWEST ARIZONA. POPS WERE BUMPED UP QUITE A BIT
AROUND YUMA/EL CENTRO/BLYTHE ACCORDINGLY.
PRECIP WILL CONTINUE THROUGH THE MORNING HOURS ON FRIDAY AS THE
UPPER LOW DIVES SOUTHWARD THROUGH ARIZONA INTO MEXICO FRIDAY
AFTERNOON. WHILE IM NOT ENTIRELY CONVINCED THERE WILL BE
THUNDER...THERE ARE A FEW HUNDRED J/KG OF MLCAPE TO WORK WITH UNDER
THE CORE OF THE UPPER LOW AND I HELD ONTO THE SLIGHT MENTION OF
THUNDER EARLY FRIDAY MORNING. AT SOME POINT DURING THE AFTERNOON THE
PRECIP SHOULD BEGIN TO TAPER OFF AS THE BEST MOISTURE CONVERGENCE
AND ISENTROPIC ASCENT WILL BE DISPLACED AWAY FROM THE FORECAST
AREA...BUT STRONGLY BACKED WINDS FROM 925-850MB COULD RESULT IN A
QUASI-STATIONARY BAND OF PRECIP SOMEWHERE IN/AROUND/TO THE NORTH OF
THE PHOENIX AREA. QPF FROM THE NAM/GFS/EURO SUGGEST A BAND OF PRECIP
FROM GLOBE TO PHOENIX TO WICKENBURG DURING THE AFTERNOON I HELD ONTO
SOME ELEVATED POPS THROUGH 00Z. CONFIDENCE IN EXACTLY HOW THE AREAL
COVERAGE WILL TURN OUT IS LOW...THUS POPS ARE SOMEWHAT BROAD-BRUSHED
THROUGH THE ENTIRE EVENT. HOWEVER...IT STILL LOOKS LIKE QPF WILL BE
IN THE 0.10-0.30 REALM FOR MOST LOCATIONS...WITH LOCALLY HIGHER
AMOUNTS AS USUAL.
THE LOW WILL SLOWLY DEPART FRIDAY NIGHT INTO SATURDAY BUT MOIST
NORTHWESTERLY FLOW WILL CONTINUE INTO THE DAY ON SATURDAY. LOOKS
LIKE A CONTINUED CHANCE OF SHOWERS AND/OR SNOW IN THE MOUNTAINS EAST
OF PHOENIX THROUGH AT LEAST 18Z SATURDAY...BUT THE DESERTS SHOULD
REMAIN DRY. WITH SNOW LEVELS ONLY EXPECTED TO FALL TO AROUND
5000-5500 FT...NEARLY ALL OF THE HIGH IMPACT HIGHER ELEVATIONS WILL
SEE PRECIP REMAIN AS RAIN AS OPPOSED TO SNOW...BUT THE HIGHEST SPOTS
COULD SEE A QUICK INCH OR TWO OF SNOW BY THE TIME THINGS DRY OUT
ENTIRELY ON SUNDAY.
THE FORECAST FOR MONDAY THROUGH MID WEEK LOOKS DRY AS THE NORTHWEST
FLOW GRADUALLY FLATTENS OUT BY TUESDAY. THERE REMAINS A VARIETY OF
SOLUTIONS SURROUNDING A LOW MOVING SOUTHWARD THROUGH THE FOUR
CORNERS WEDNESDAY AFTERNOON INTO THURSDAY. TODAYS 00Z RUNS OF THE
EURO/GFS KEEP THIS LOW DISPLACED WELL NORTH AND EAST OF THE FORECAST
AREA. THIS IDEA SEEMS TO HAVE THE SUPPORT OF THEIR RESPECTIVE
ENSEMBLES AS WELL. KEPT A DRY FORECAST IN PLACE FOR CHRISTMAS DAY
BUT WILL NEED TO MONITOR TRENDS IN THE EVENT THE MODELS RETURN TO A
DEEPER AND MORE SIGNIFICANT SYSTEM NEXT WEDNESDAY/THURSDAY.
&&
.AVIATION...
SOUTH-CENTRAL ARIZONA...INCLUDING KPHX...KIWA...AND KSDL...
EASTERLY WINDS TO PERSIST THROUGH THE MORNING HOURS...WITH THICK
CIRRUS COVER GENERALLY THINNING. SURFACE WINDS INCREASE AFTER 17Z
WITH A SOUTHERLY CROSS COMPONENT AOA 10KT AND HIGHER GUSTS UP TO
20KT POSSIBLE THIS AFTERNOON. INCREASING CIGS BELOW 6KFT LIKELY
THURSDAY EVENING...WITH SHOWERS AND ISOLATED THUNDERSTORMS
DEVELOPING OVERNIGHT INTO FRIDAY MORNING.
SOUTHEAST CALIFORNIA/SOUTHWEST ARIZONA...INCLUDING KIPL AND KBLH...
EXPECT INCREASED SOUTHWEST TO WEST WINDS...WITH GUSTS OF 25-30KT
COMMON THROUGH THE DAY. INCREASING/LOWERING CLOUD DECKS ALSO
EXPECTED BY THE LATE AFTERNOON WITH LOWER CIGS AROUND 6KFT AND
SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS POSSIBLE THIS
EVENING...CONTINUING INTO FRIDAY MORNING.
AVIATION DISCUSSION NOT UPDATED FOR AMENDED TAFS.
&&
.FIRE WEATHER...
SATURDAY THROUGH WEDNESDAY...
MOSTLY SUNNY SKIES WILL PREVAIL...AND A GRADUAL WARMING TREND WILL
TAKE PLACE THROUGH THE WEEKEND. HIGH TEMPERATURES WILL STAY BELOW
SEASONAL NORMALS...ESPECIALLY OVER SOUTH CENTRAL ARIZONA WHERE MAX
READINGS ARE EXPECTED TO BE THE UPPER 50S TO AROUND 60 DEGREES.
NORTHWEST WINDS WILL REMAIN BREEZY ACROSS SOUTHWEST ARIZONA AND
SOUTHEAST CALIFORNIA SATURDAY...WITH A LIGHTER WIND REGIME EXPECTED
AREA-WIDE SUNDAY THROUGH TUESDAY. MINIMUM HUMIDITIES WILL REMAIN
ELEVATED AND MOSTLY GREATER THAN 20 PERCENT THROUGH THE PERIOD.
&&
.PSR WATCHES/WARNINGS/ADVISORIES...
AZ...NONE.
CA...NONE.
&&
$$
VISIT US ON FACEBOOK...TWITTER...AND AT WEATHER.GOV/PHOENIX
DISCUSSION...KUHLMAN
PREVIOUS DISCUSSION...LEINS
AVIATION...MEYERS
FIRE WEATHER...MEYERS
AREA FORECAST DISCUSSION
NWS DENVER/BOULDER CO
352 PM MST THU DEC 19 2013
.SHORT TERM...SOUTHWEST FLOW ALOFT CURRENTLY ACROSS COLORADO. MID
LEVEL MOISTURE SPREADING BACK INTO THE MOUNTAINS AND FROM WEB CAMS
IT APPEARS THERE IS SOME LIGHT SNOW OVER THE HIGHER MOUNTAINS.
SNOW COVERAGE WILL GRADUALLY INCREASE THIS EVENING AS MOISTURE AND
OROGRAPHICS INCREASE...WITH THE FLOW FAVORING THE NORTHERN
MOUNTAINS. BUT THE SNOW WILL BE LIGHT DUE TO LACK OF ANY MID LEVEL
ASCENT... WITH ACCUMULATIONS LESS THAN 3 INCHES. AFTER
MIDNIGHT...THE SNOW WILL DECREASE AGAIN AS THE FLOW ALOFT WEAKENS
ALONG WITH WEAKENING OROGRAPHICS. ALONG FOOTHILLS AND ACROSS
PLAINS...COLD FRONT CURRENTLY PUSHING INTO NORTHERN COLORADO WITH
SOME GUSTS TO AROUND 25 KTS. FRONT WILL CONTINUE TO MOVE SOUTH
THROUGH THE EVENING WITH UPSLOPE DEVELOPING AND LOW LEVEL MOISTURE
INCREASING. CROSS SECTIONS SHOW UPSLOPE TO BE AROUND 700 MB NEAR
THE FOOTHILLS. THERE STILL LOOKS TO BE WINDOW BETWEEN 02Z AND 07Z
FOR SOME LIGHT SNOW TO DEVELOP...MAINLY IN AND NEAR THE FOOTHILLS.
LATEST RAP ALSO SHOWS SOME CHANCE ALONG THE PALMER. STILL THE BEST
CHANCE FOR SNOW WILL BE ACROSS ZONE 35 WHERE LOW LEVEL UPSLOPE
WILL BE AIDED WITH THE SOUTHWEST FLOW ALOFT AND WILL CONTINUE
LIKELY POPS THERE WITH SNOW AMOUNTS AROUND AN INCH. WILL KEEP A
CHANCE OF LIGHT SNOW ALONG THE URBAN CORRIDOR AND SOUTHERN
FOOTHILLS WITH LOWER POPS FURTHER EAST. AFTER 07Z THE UPSLOPE
WEAKENS AND THE AIRMASS BEGINS TO DRY OUT...LOWER POPS STILL LOOK
REASONABLE. AIRMASS FAIRLY COLD OVER WYOMING AND NEBRASKA...AND
THIS AIR SHOULD STAY TO THE NORTH AND EAST OF COLORADO.
STILL...OVERNIGHT TEMPERATURES TO DROP INTO THE TEENS ACROSS THE
PLAINS...WITH SINGLE DIGIT READINGS NEAR THE WYOMING AND NEBRASKA
PANHANDLE. ON FRIDAY...FLOW ALOFT BECOMES WESTERLY...A BIT
NORTHWEST AT MOUNTAIN TOP DURING THE AFTERNOON. THERE IS ALSO SOME
INCREASE IN MID LEVEL ASCENT. THIS WILL RESULT IN SOME INCREASE IN
LIGHT SNOW BY THE AFTERNOON. STILL ACCUMULATIONS WILL REMAIN
LIGHT. ACROSS PLAINS...A DRIER BUT COLD AIRMASS WILL BE OVER THE
AREA. THERE MAY BE SOME LINGERING FLURRIES DURING THE
MORNING...OTHERWISE NO SNOW IS EXPECTED. TEMPERATURES WILL SLOWLY
WARM INTO THE 30S ACROSS THE PLAINS...EXCEPT UPPER 20S FAR
NORTHEAST CORNER.
.LONG TERM...DRYING AND SUBSIDENCE THROUGH TOMORROW EVENING SHOULD
BRING A DECREASE OF SNOW SHOWERS IN THE MOUNTAINS. HOWEVER...THE
NEXT SHORT WAVE IS QUICK ON ITS HEELS WHICH WILL BRING A RETURN OF
HIGH COUNTRY SNOWFALL BY EARLY SATURDAY MORNING. MOISTURE IS
DEEPER BUT STABILITY PROFILE IS ONLY MARGINAL WITH A STABLE LAYER
NEAR MOUNTAIN TOP BUT OK 5-6C/KM LAPS RATES FARTHER UP. THE END
RESULT SHOULD BE A LIGHT SNOW EVENT FOR MOUNTAINS STANDARDS WITH
ANOTHER 1-4 INCHES SATURDAY.
BY LATE SATURDAY AFTERNOON AND EVENING...THERE IS SOME LOW LEVEL
ANTICYCLONIC TURNING WHICH COULD ALLOW A LITTLE SNOW TO SPILL OUT
ONTO THE PLAINS IN SHALLOW UPSLOPE. AT THIS TIME...THIS ONLY
LOOKS LIKE A LIGHT DUSTING IF ANYTHING SO WILL CONTINUE THE LOW
POPS FOR SATURDAY EVENING.
BY LATE SUNDAY...ANOTHER FAST MOVING SHORT WAVE MAY APPROACH FROM
THE NORTHWEST BRINGING MORE MOUNTAIN SNOW SHOWERS. AGAIN..THERE
MAY BE A LOW CHANCE ON THE PLAINS WITH A WEAK FRONTAL SURGE AND
LIFT ASSOCIATED WITH LEFT EXIT REGION OF UPPER JET. HAVE THROWN IN
SOME POPS FOR THE NORTHEAST CORNER OF THE STATE...BUT EVENTUALLY MAY
HAVE TO INCLUDE THE FRONT RANGE URBAN CORRIDOR CONSIDERING THIS IS
A NORTHWEST FLOW EVENT WITH A STRONG UPPER JET. TEMPERATURES WILL
AVERAGE A FEW DEGREES BELOW NORMAL FOR THE SATURDAY-SUNDAY PERIOD.
MAINLY DRY AND WARMER WEATHER IS EXPECTED MONDAY INTO TUESDAY.
THEN...ANOTHER SHORT WAVE IS ADVERTISED BY MOST MEDIUM RANGE
MODELS TO DROP ACROSS THE STATE CHRISTMAS EVE INTO CHRISTMAS
MORNING. TIMING IS BECOMING INCREASINGLY DIFFICULT IN THIS FAST
NORTHWEST FLOW PATTERN...SO EXTENDED PERIODS OF LOW POPS IS
WARRANTED FOR NOW. THAT PARTICULAR WAVE WILL BE THE PLAINS BEST
CHANCE OF A WHITE CHRISTMAS.
&&
.AVIATION...FRONT MOVING INTO NORTHERN WELD COUNTY...SHOULD REACH
THE AREA AIRPORTS BY 00Z. NORTHERLY WINDS WILL GUST TO AROUND 25
KTS WITH THE FRONT PASSAGE. CLOUDS WILL CONTINUE TO INCREASE WITH
CEILINGS LOWERING TO IFR BY 01Z WITH DECREASING WINDS. THERE IS
STILL A CHANCE FOR LIGHT SNOW BETWEEN 02Z AND 08Z...THOUGH THIS
CHANCE IS DECREASING AS THE MOISTURE IS BECOMING MORE SHALLOW.
WILL CONTINUE THE VCSH FOR NOW. CONDITIONS TO IMPROVE AFTER 08Z
WITH WINDS SHIFTING TO THE SOUTHEAST. AFTER 13Z SHOULD SEE
CEILINGS IMPROVE TO VFR.
&&
.BOU WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...D-L
LONG TERM....BARJENBRUCH
AVIATION...D-L
AREA FORECAST DISCUSSION
NWS TAUNTON MA
433 PM EST THU DEC 19 2013
.SYNOPSIS...
DRY WEATHER WILL CONTINUE TONIGHT AND INTO TOMORROW...ISOLATED
SHOWERS ARE POSSIBLE NORTH OF ROUTE 2. A COLD FRONT WILL STALL TO
OUR NORTH TOMORROW. THIS STALLED FRONT WILL RESULT IN PERIODS OF
UNSETTLED WEATHER FRI NIGHT THROUGH EARLY MON. DRIER AND COOLER
WEATHER ARRIVES EARLY NEXT WEEK.
&&
.NEAR TERM /UNTIL 6 AM FRIDAY MORNING/...
4 PM UPDATE...
FORECAST REMAINS ON TRACK FOR THIS AFTERNOON AS WINDS ARE
STARTING TO DIE DOWN AND TEMPS ARE DROPPING. LATEST SATELLITE
IMAGERY SHOWS CLOUDS WILL CONTINUE TO FILTER INTO THE REGION AND
BECOME MORE WIDESPREAD THIS EVENING.
TONIGHT...
STATIONARY BOUNDARY WILL SET UP ACROSS NORTHERN NEW ENGLAND
TONIGHT AS A RESULT OF AN APPROACHING LOW PRESSURE SYSTEM FROM THE
GREAT LAKES. THIS FRONT WILL ALLOW FOR PRECIP TO DEVELOP ALONG IT
OVERNIGHT AND INTO TOMORROW MORNING. LATEST GUIDANCE KEEPS THIS
FRONT FARTHER NORTH OF THE REGION. HI-RES GUIDANCE AND HRRR KEEP
ALL THE PRECIP NORTH OF THE REGION AS WELL. HOWEVER DID KEEP SOME
LINGERING POPS FOR THE EARLY MORNING HOURS. THIS MAY ALLOW FOR
SOME LIGHT FREEZING RAIN IN THE FAR NORTHERN PORTION OF
FRANKLIN...HILLSBOROUGH AND CHESHIRE COUNTIES. BUT BECAUSE OF THE
LOW CONFIDENCE AND THE FACT THAT HI-RES GUIDANCE KEEPS THIS
PORTION MAINLY DRY DID NOT ISSUE ANY HEADLINES AT THIS TIME.
&&
.SHORT TERM /6 AM FRIDAY MORNING THROUGH FRIDAY NIGHT/...
FRIDAY INTO FRIDAY NIGHT...
ABOVE AVERAGE TEMPERATURES WILL CONTINUE INTO FRIDAY HOWEVER BY
JUST A FEW DEGREES. INITIALLY THOUGHT THAT TEMPS TOMORROW WILL BE
WELL INTO THE 50S AS WE HIT THE MID 40S TODAY. YET LOOKING AT
SOUNDING DATA APPEARS THAT A SUBSTANCE INVERSION WILL BE SET UP
OVER THE REGION. SO WHILE 925 MB TEMPS WILL BE BETWEEN 7C TO
9C...WE MAY BE IN THE LOW TO UPPER 40S ACROSS THE AREA AT THE
SURFACE. THE MAX T GRID FOR TOMORROW MAY BE TO OPTIMISTIC. A STRAY
SHOWER OR TWO MAY MOVE ACROSS THE REGION TOMORROW AS THE BOUNDARY
BEGINS TO SLIDE SOUTHWARD...BUT OVERALL FEEL MAINLY DRY WEATHER
FOR TOMORROW ESPECIALLY SOUTH OF ROUTE 2.
THAT FRONT WILL SLIDE FARTHER SOUTH AND CLOSER TO THE NW COUNTIES ON
FRIDAY NIGHT INCREASING THE POTENTIAL FOR SOME PRECIP AS A LOW
PRESSURE MOVES ALONG THE BOUNDARY. SURFACE TEMPS WILL BE NEAR OR
ABOVE FREEZING FOR THIS TIMEFRAME SO THE POTENTIAL FOR ICING IS
LESS. THE HIGHEST LOCATION FOR PRECIP TO OCCURS WILL BE REGIONS
NORTH OF ROUTE 2 WITH AN ISOLATED CHANCE NORTH OF THE MASS PIKE.
TEMPERATURES OVERNIGHT WILL ONLY DROP SLIGHTLY AS OVERCAST SKIES AND
WEAK WAA WILL LIMIT RADIATIONAL COOLING.
&&
.LONG TERM /SATURDAY THROUGH THURSDAY/...
* UNSETTLED WEATHER OVER THE WEEKEND
* DRIER...COOLER WEATHER EXPECTED EARLY NEXT WEEK
SATURDAY...COLD FRONT IS NEARLY STATIONARY ACROSS
NORTHERN/CENTRAL NEW ENGLAND EARLY IN THE DAY...WITH MODELS
INDICATING THIS FRONT WILL SLOWLY PUSH SOUTHWARD DURING THE DAY.
LIGHT RAIN SHOWERS POSSIBLE OVER SOUTHERN NH/NORTHERN MA IN THE
MORNING...WITH INCREASING CHANCES FOR RAIN SHOWERS TO THE SOUTH IN
THE AFTERNOON. QPF AMOUNTS EXPECTED TO BE LIGHT.
SATURDAY NIGHT...AGREEMENT BETWEEN THE GFS AND ECMWF THAT FRONT WILL
BECOME DRAPED IN THE VICINITY OF SOUTHERN NH/NORTHERN MA DURING THIS
TIMEFRAME. THERE IS STILL UNCERTAINTY REGARDING THE TEMPERATURE
PROFILE SATURDAY NIGHT AND SUNDAY...BUT THE TREND CONTINUES TO BE
KEEPING MOST OF THE CWA OUT OF THE MUCH COLDER TEMPERATURES AND
FREEZING RAIN. THE MAIN CONCERN AT THIS POINT IS SURFACE
TEMPERATURES IN THE FAR NORTHERN TIER OF THE FORECAST AREA...IN
PARTICULAR SOUTHERN NEW HAMPSHIRE. THERE IS A RISK FOR A PERIOD OF
FREEZING RAIN IN CHESHIRE AND HILLSBOROUGH COUNTIES LATE SATURDAY
NIGHT INTO SUNDAY MORNING...WITH A VERY LOW CHANCE OF FREEZING RAIN
DURING THIS TIMEFRAME OVER EXTREME NORTHERN MA.
SUNDAY...FRONT BEGINS TO PUSH NORTHWARD AS A WARM FRONT DURING THE
DAY...ANY FREEZING PRECIPITATION SHOULD CHANGE OVER TO RAIN SHOWERS
AS THE MORNING PROGRESSES. QPF TOTALS FOR SUNDAY ARE UNCERTAIN FOR
SOUTHERN NEW ENGLAND...EARLY INDICATIONS ARE 0.25 INCH TO AN
INCH...BUT IN ADDITION TO THIS RAIN THERE WILL BE SNOWMELT. ACROSS
MOST OF MASSACHUSETTS...AS WELL AS N CT AND RI...SURFACE DEWPOINTS
ARE EXPECTED TO CLIMB INTO THE 50S. HIGH TEMPERATURES MAY REACH MID
50S TO AROUND 60. THIS WITH A 10 TO 15 MPH SOUTHERLY SURFACE WIND
WILL PROMPT CONSIDERABLE SNOWMELT. THE SNOWMELT ALONG WITH
MODERATE QPF COULD CAUSE FLOODING IN LOW LYING AND POOR DRAINAGE
AREAS. ANY DRAINS THAT ARE SNOW CLOGGED COULD POSE A FLOOD RISK.
SUNDAY NIGHT THRU MONDAY...CONTINUED CHANCE FOR RAIN SHOWERS UNTIL
ARCTIC FRONT MOVES SOUTHEAST OF SOUTHERN NEW ENGLAND MONDAY. PRECIP
COULD END AS A BRIEF PERIOD OF SNOW SHOWERS.
MONDAY THROUGH CHRISTMAS DAY...WITH THE ARCTIC FRONT FINALLY MOVES
SOUTHEAST OF SOUTHERN NEW ENGLAND...MODELS CONTINUE TO INDICATE COLD
HIGH PRESSURE BUILDING IN BEHIND THE FRONT WITH SUBSTANTIALLY
COLDER TEMPERATURES FOR CHRISTMAS EVE AND DAY.
THURSDAY...MODELS ARE INDICATING POTENTIAL FOR APPROACH OF A COLD
FRONT FROM THE WEST...WITH SOMEWHAT MILDER AIR MOVING IN AHEAD OF
THE FRONT. WILL HAVE A CHANCE OF RAIN/SNOW SHOWERS LATE THURSDAY
AND THURSDAY NIGHT.
&&
.AVIATION /22Z THURSDAY THROUGH TUESDAY/...
FORECASTER CONFIDENCE LEVELS...
LOW...LESS THAN 30 PERCENT.
MODERATE...30 TO 60 PERCENT.
HIGH...GREATER THAN 60 PERCENT.
NEAR TERM /THROUGH FRIDAY NIGHT/...
WINDS WILL DIE DOWN AFTER SUNSET. HIGH CONFIDENCE VFR
TONIGHT...WITH A LOW POTENTIAL FOR SOME MVFR CONDITIONS IN
SHOWERS AND POSSIBLE ICING ACROSS S NH.
FRIDAY AND FRIDAY NIGHT...
HIGH CONFIDENCE IN VFR TOMORROW WITH SOME SHOWERS APPROACHING THE
NW PORTION OF THE REGION BY LATE FRIDAY NIGHT. COULD BE SOME MVFR
MIXED IN WITH THE SHOWERS ESP ACROSS NORTHERN SITES.
KBOS TAF...HIGH CONFIDENCE IN TAF.
KBDL TAF...HIGH CONFIDENCE IN TAF.
OUTLOOK...SATURDAY THROUGH TUESDAY...
SATURDAY...MODERATE CONFIDENCE. MAINLY VFR.
SATURDAY NIGHT THROUGH MONDAY MORNING...LOW CONFIDENCE. MVFR/IFR
CONDITIONS DEVELOP IN MAINLY RAIN SHOWERS. FREEZING RAIN IS
POSSIBLE MAINLY THROUGH SOUTHERN NEW HAMPSHIRE.
MONDAY AFTERNOON/EVENING/NIGHT...HIGH CONFIDENCE. IMPROVEMENT TO
VFR BEHIND ARCTIC FRONT. WINDS SHIFT FROM SW TO NW.
TUESDAY...HIGH CONFIDENCE VFR.
&&
.MARINE...
FORECASTER CONFIDENCE LEVELS...
LOW...LESS THAN 30 PERCENT.
MODERATE...30 TO 60 PERCENT.
HIGH...GREATER THAN 60 PERCENT.
NEAR TERM /THROUGH FRIDAY NIGHT/...HIGH CONFIDENCE
SW WINDS ARE WEAKENING THIS EVENING AND INTO THE OVERNIGHT. SEAS
WILL ALSO BEGIN TO RELAX AS WELL. ALTERED SCA IN ACCORDANCES.
LIGHT SW FLOW WILL CONTINUE INTO TOMORROW BUT BEGIN TO PULSE UP BY
TOMORROW NIGHT. SEAS WILL LINGER AROUND 5 FT ESP ACROSS THE
SOUTHER OUTER WATERS TOMORROW AND INTO TOMORROW NIGHT...THEREFORE
HAVE EXTENDED THE SCA. DID UNDERCUT SEAS FOR FRIDAY NIGHT AS THEY
SEEMED VERY ROBUST IN A SW FLOW REGIME.
OUTLOOK...SATURDAY THROUGH TUESDAY...
SOUTHWESTERLY WINDS WITH PERIODS OF GUSTS 25 TO 30 KTS PERSIST
THROUGH MUCH OF THE LONG TERM. WINDS SHIFT TO THE NORTHWEST AS AN
ARCTIC FRONT MOVES ACROSS THE WATERS MONDAY. WAVES BUILD AND
DIMINISH AS WAVES OF LOW PRESSURE MOVE ALONG AN ARCTIC FRONT THROUGH
NORTHERN NEW ENGLAND BUT GENERALLY REMAIN ABOVE 5 FEET ON THE OUTER
WATERS AT LEAST. SEAS MAY BUILD TO 7 TO 10 FEET ON THE OUTER WATERS
DURING SUN AND SUN NIGHT. MUCH OF THIS TIME WILL LIKELY NEED SMALL
CRAFT ADVISORIES UP FOR AT LEAST THE OUTER WATERS...BUT OVERALL
CONFIDENCE IS LOW ON TIMING.
&&
.CLIMATE...
RECORD HIGHS FOR DECEMBER 22ND...
HARTFORD /BDL/ 59 DEGREES...1990
WORCESTER /ORH/ 63 DEGREES...1923
BOSTON /BOS/ 62 DEGREES...1990
PROVIDENCE /PVD/ 61 DEGREES...1990
&&
.BOX WATCHES/WARNINGS/ADVISORIES...
CT...NONE.
MA...NONE.
NH...NONE.
RI...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL 8 PM EST THIS EVENING FOR
ANZ231>234-251.
SMALL CRAFT ADVISORY UNTIL 6 AM EST FRIDAY FOR ANZ235-237.
SMALL CRAFT ADVISORY UNTIL 10 PM EST THIS EVENING FOR ANZ250.
SMALL CRAFT ADVISORY UNTIL 7 AM EST SATURDAY FOR ANZ254>256.
&&
$$
SYNOPSIS...DUNTEN
NEAR TERM...DUNTEN
SHORT TERM...DUNTEN/NMB
LONG TERM...NMB
AVIATION...DUNTEN/NMB
MARINE...DUNTEN/NMB
CLIMATE...STAFF
AREA FORECAST DISCUSSION
NWS TAUNTON MA
427 PM EST THU DEC 19 2013
.SYNOPSIS...
DRY WEATHER WILL CONTINUE TONIGHT AND INTO TOMORROW...ISOLATED
SHOWERS ARE POSSIBLE NORTH OF ROUTE 2. A COLD FRONT WILL STALL TO
OUR NORTH TOMORROW. THIS STALLED FRONT WILL RESULT IN PERIODS OF
UNSETTLED WEATHER FRI NIGHT THROUGH EARLY MON. DRIER AND COOLER
WEATHER ARRIVES EARLY NEXT WEEK.
&&
.NEAR TERM /UNTIL 6 AM FRIDAY MORNING/...
4 PM UPDATE...
FORECAST REMAINS ON TRACK FOR THIS AFTERNOON AS WINDS ARE
STARTING TO DIE DOWN AND TEMPS ARE DROPPING. LATEST SATELLITE
IMAGERY SHOWS CLOUDS WILL CONTINUE TO FILTER INTO THE REGION AND
BECOME MORE WIDESPREAD THIS EVENING.
TONIGHT...
STATIONARY BOUNDARY WILL SET UP ACROSS NORTHERN NEW ENGLAND
TONIGHT AS A RESULT OF AN APPROACHING LOW PRESSURE SYSTEM FROM THE
GREAT LAKES. THIS FRONT WILL ALLOW FOR PRECIP TO DEVELOP ALONG IT
OVERNIGHT AND INTO TOMORROW MORNING. LATEST GUIDANCE KEEPS THIS
FRONT FARTHER NORTH OF THE REGION. HI-RES GUIDANCE AND HRRR KEEP
ALL THE PRECIP NORTH OF THE REGION AS WELL. HOWEVER DID KEEP SOME
LINGERING POPS FOR THE EARLY MORNING HOURS. THIS MAY ALLOW FOR
SOME LIGHT FREEZING RAIN IN THE FAR NORTHERN PORTION OF
FRANKLIN...HILLSBOROUGH AND CHESHIRE COUNTIES. BUT BECAUSE OF THE
LOW CONFIDENCE AND THE FACT THAT HI-RES GUIDANCE KEEPS THIS
PORTION MAINLY DRY DID NOT ISSUE ANY HEADLINES AT THIS TIME.
&&
.SHORT TERM /6 AM FRIDAY MORNING THROUGH FRIDAY NIGHT/...
FRIDAY INTO FRIDAY NIGHT...
ABOVE AVERAGE TEMPERATURES WILL CONTINUE INTO FRIDAY HOWEVER BY
JUST A FEW DEGREES. INITIALLY THOUGHT THAT TEMPS TOMORROW WILL BE
WELL INTO THE 50S AS WE HIT THE MID 40S TODAY. YET LOOKING AT
SOUNDING DATA APPEARS THAT A SUBSTANCE INVERSION WILL BE SET UP
OVER THE REGION. SO WHILE 925 MB TEMPS WILL BE BETWEEN 7C TO
9C...WE MAY BE IN THE LOW TO UPPER 40S ACROSS THE AREA AT THE
SURFACE. THE MAX T GRID FOR TOMORROW MAY BE TO OPTIMISTIC. A STRAY
SHOWER OR TWO MAY MOVE ACROSS THE REGION TOMORROW AS THE BOUNDARY
BEGINS TO SLIDE SOUTHWARD...BUT OVERALL FEEL MAINLY DRY WEATHER
FOR TOMORROW ESPECIALLY SOUTH OF ROUTE 2.
THAT FRONT WILL SLIDE FARTHER SOUTH AND CLOSER TO THE NW COUNTIES ON
FRIDAY NIGHT INCREASING THE POTENTIAL FOR SOME PRECIP AS A LOW
PRESSURE MOVES ALONG THE BOUNDARY. SURFACE TEMPS WILL BE NEAR OR
ABOVE FREEZING FOR THIS TIMEFRAME SO THE POTENTIAL FOR ICING IS
LESS. THE HIGHEST LOCATION FOR PRECIP TO OCCURS WILL BE REGIONS
NORTH OF ROUTE 2 WITH AN ISOLATED CHANCE NORTH OF THE MASS PIKE.
TEMPERATURES OVERNIGHT WILL ONLY DROP SLIGHTLY AS OVERCAST SKIES AND
WEAK WAA WILL LIMIT RADIATIONAL COOLING.
&&
.LONG TERM /SATURDAY THROUGH THURSDAY/...
* UNSETTLED WEATHER OVER THE WEEKEND
* DRIER...COOLER WEATHER EXPECTED EARLY NEXT WEEK
SATURDAY...COLD FRONT IS NEARLY STATIONARY ACROSS
NORTHERN/CENTRAL NEW ENGLAND EARLY IN THE DAY...WITH MODELS
INDICATING THIS FRONT WILL SLOWLY PUSH SOUTHWARD DURING THE DAY.
LIGHT RAIN SHOWERS POSSIBLE OVER SOUTHERN NH/NORTHERN MA IN THE
MORNING...WITH INCREASING CHANCES FOR RAIN SHOWERS TO THE SOUTH IN
THE AFTERNOON. QPF AMOUNTS EXPECTED TO BE LIGHT.
SATURDAY NIGHT...AGREEMENT BETWEEN THE GFS AND ECMWF THAT FRONT WILL
BECOME DRAPED IN THE VICINITY OF SOUTHERN NH/NORTHERN MA DURING THIS
TIMEFRAME. THERE IS STILL UNCERTAINTY REGARDING THE TEMPERATURE
PROFILE SATURDAY NIGHT AND SUNDAY...BUT THE TREND CONTINUES TO BE
KEEPING MOST OF THE CWA OUT OF THE MUCH COLDER TEMPERATURES AND
FREEZING RAIN. THE MAIN CONCERN AT THIS POINT IS SURFACE
TEMPERATURES IN THE FAR NORTHERN TIER OF THE FORECAST AREA...IN
PARTICULAR SOUTHERN NEW HAMPSHIRE. THERE IS A RISK FOR A PERIOD OF
FREEZING RAIN IN CHESHIRE AND HILLSBOROUGH COUNTIES LATE SATURDAY
NIGHT INTO SUNDAY MORNING...WITH A VERY LOW CHANCE OF FREEZING RAIN
DURING THIS TIMEFRAME OVER EXTREME NORTHERN MA.
SUNDAY...FRONT BEGINS TO PUSH NORTHWARD AS A WARM FRONT DURING THE
DAY...ANY FREEZING PRECIPITATION SHOULD CHANGE OVER TO RAIN SHOWERS
AS THE MORNING PROGRESSES. QPF TOTALS FOR SUNDAY ARE UNCERTAIN FOR
SOUTHERN NEW ENGLAND...EARLY INDICATIONS ARE 0.25 INCH TO AN
INCH...BUT IN ADDITION TO THIS RAIN THERE WILL BE SNOWMELT. ACROSS
MOST OF MASSACHUSETTS...AS WELL AS N CT AND RI...SURFACE DEWPOINTS
ARE EXPECTED TO CLIMB INTO THE 50S. HIGH TEMPERATURES MAY REACH MID
50S TO AROUND 60. THIS WITH A 10 TO 15 MPH SOUTHERLY SURFACE WIND
WILL PROMPT CONSIDERABLE SNOWMELT. THE SNOWMELT ALONG WITH
MODERATE QPF COULD CAUSE FLOODING IN LOW LYING AND POOR DRAINAGE
AREAS. ANY DRAINS THAT ARE SNOW CLOGGED COULD POSE A FLOOD RISK.
SUNDAY NIGHT THRU MONDAY...CONTINUED CHANCE FOR RAIN SHOWERS UNTIL
ARCTIC FRONT MOVES SOUTHEAST OF SOUTHERN NEW ENGLAND MONDAY. PRECIP
COULD END AS A BRIEF PERIOD OF SNOW SHOWERS.
MONDAY THROUGH CHRISTMAS DAY...WITH THE ARCTIC FRONT FINALLY MOVES
SOUTHEAST OF SOUTHERN NEW ENGLAND...MODELS CONTINUE TO INDICATE COLD
HIGH PRESSURE BUILDING IN BEHIND THE FRONT WITH SUBSTANTIALLY
COLDER TEMPERATURES FOR CHRISTMAS EVE AND DAY.
THURSDAY...MODELS ARE INDICATING POTENTIAL FOR APPROACH OF A COLD
FRONT FROM THE WEST...WITH SOMEWHAT MILDER AIR MOVING IN AHEAD OF
THE FRONT. WILL HAVE A CHANCE OF RAIN/SNOW SHOWERS LATE THURSDAY
AND THURSDAY NIGHT.
&&
.AVIATION /22Z THURSDAY THROUGH TUESDAY/...
FORECASTER CONFIDENCE LEVELS...
LOW...LESS THAN 30 PERCENT.
MODERATE...30 TO 60 PERCENT.
HIGH...GREATER THAN 60 PERCENT.
NEAR TERM /THROUGH FRIDAY NIGHT/...
WINDS WILL DIE DOWN AFTER SUNSET. HIGH CONFIDENCE VFR
TONIGHT...WITH A LOW POTENTIAL FOR SOME MVFR CONDITIONS IN
SHOWERS AND POSSIBLE ICING ACROSS S NH.
FRIDAY AND FRIDAY NIGHT...
HIGH CONFIDENCE IN VFR TOMORROW WITH SOME SHOWERS APPROACHING THE
NW PORTION OF THE REGION BY LATE FRIDAY NIGHT. COULD BE SOME MVFR
MIXED IN WITH THE SHOWERS ESP ACROSS NORTHERN SITES.
KBOS TAF...HIGH CONFIDENCE IN TAF.
KBDL TAF...HIGH CONFIDENCE IN TAF.
OUTLOOK...SATURDAY THROUGH TUESDAY...
SATURDAY...MODERATE CONFIDENCE. MAINLY VFR.
SATURDAY NIGHT THROUGH MONDAY MORNING...LOW CONFIDENCE. MVFR/IFR
CONDITIONS DEVELOP IN MAINLY RAIN SHOWERS. FREEZING RAIN IS
POSSIBLE MAINLY THROUGH SOUTHERN NEW HAMPSHIRE.
MONDAY AFTERNOON/EVENING/NIGHT...HIGH CONFIDENCE. IMPROVEMENT TO
VFR BEHIND ARCTIC FRONT. WINDS SHIFT FROM SW TO NW.
TUESDAY...HIGH CONFIDENCE VFR.
&&
.MARINE...
FORECASTER CONFIDENCE LEVELS...
LOW...LESS THAN 30 PERCENT.
MODERATE...30 TO 60 PERCENT.
HIGH...GREATER THAN 60 PERCENT.
NEAR TERM /THROUGH FRIDAY NIGHT/...HIGH CONFIDENCE
SW WINDS ARE WEAKENING THIS EVENING AND INTO THE OVERNIGHT. SEAS
WILL ALSO BEGIN TO RELAX AS WELL. ALTERED SCA IN ACCORDANCES.
LIGHT SW FLOW WILL CONTINUE INTO TOMORROW BUT BEGIN TO PULSE UP BY
TOMORROW NIGHT. SEAS WILL LINGER AROUND 5 FT ESP ACROSS THE
SOUTHER OUTER WATERS TOMORROW AND INTO TOMORROW NIGHT...THEREFORE
HAVE EXTENDED THE SCA. DID UNDERCUT SEAS FOR FRIDAY NIGHT AS THEY
SEEMED VERY ROBUST IN A SW FLOW REGIME.
OUTLOOK...SATURDAY THROUGH TUESDAY...
SOUTHWESTERLY WINDS WITH PERIODS OF GUSTS 25 TO 30 KTS PERSIST
THROUGH MUCH OF THE LONG TERM. WINDS SHIFT TO THE NORTHWEST AS AN
ARCTIC FRONT MOVES ACROSS THE WATERS MONDAY. WAVES BUILD AND
DIMINISH AS WAVES OF LOW PRESSURE MOVE ALONG AN ARCTIC FRONT THROUGH
NORTHERN NEW ENGLAND BUT GENERALLY REMAIN ABOVE 5 FEET ON THE OUTER
WATERS AT LEAST. SEAS MAY BUILD TO 7 TO 10 FEET ON THE OUTER WATERS
DURING SUN AND SUN NIGHT. MUCH OF THIS TIME WILL LIKELY NEED SMALL
CRAFT ADVISORIES UP FOR AT LEAST THE OUTER WATERS...BUT OVERALL
CONFIDENCE IS LOW ON TIMING.
&&
.BOX WATCHES/WARNINGS/ADVISORIES...
CT...NONE.
MA...NONE.
NH...NONE.
RI...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL 8 PM EST THIS EVENING FOR
ANZ231>234-251.
SMALL CRAFT ADVISORY UNTIL 6 AM EST FRIDAY FOR ANZ235-237.
SMALL CRAFT ADVISORY UNTIL 10 PM EST THIS EVENING FOR ANZ250.
SMALL CRAFT ADVISORY UNTIL 7 AM EST SATURDAY FOR ANZ254>256.
&&
$$
SYNOPSIS...DUNTEN
NEAR TERM...DUNTEN
SHORT TERM...DUNTEN/NMB
LONG TERM...NMB
AVIATION...DUNTEN/NMB
MARINE...DUNTEN/NMB
AREA FORECAST DISCUSSION
NWS TAUNTON MA
358 PM EST THU DEC 19 2013
.SYNOPSIS...
DRY WEATHER WILL CONTINUE TONIGHT AND INTO TOMORROW...ISOLATED
SHOWERS ARE POSSIBLE NORTH OF ROUTE 2. A COLD FRONT WILL STALL TO
OUR NORTH TOMORROW. THIS STALLED FRONT WILL RESULT IN PERIODS OF
UNSETTLED WEATHER FRI NIGHT THROUGH EARLY MON. DRIER AND COOLER
WEATHER ARRIVES EARLY NEXT WEEK.
&&
.NEAR TERM /UNTIL 6 AM FRIDAY MORNING/...
4 PM UPDATE...
FORECAST REMAINS ON TRACK FOR THIS AFTERNOON AS WINDS ARE
STARTING TO DIE DOWN AND TEMPS ARE DROPPING. LATEST SATELLITE
IMAGERY SHOWS CLOUDS WILL CONTINUE TO FILTER INTO THE REGION AND
BECOME MORE WIDESPREAD THIS EVENING.
TONIGHT...
STATIONARY BOUNDARY WILL SET UP ACROSS NORTHERN NEW ENGLAND
TONIGHT AS A RESULT OF AN APPROACHING LOW PRESSURE SYSTEM FROM THE
GREAT LAKES. THIS FRONT WILL ALLOW FOR PRECIP TO DEVELOP ALONG IT
OVERNIGHT AND INTO TOMORROW MORNING. LATEST GUIDANCE KEEPS THIS
FRONT FARTHER NORTH OF THE REGION. HI-RES GUIDANCE AND HRRR KEEP
ALL THE PRECIP NORTH OF THE REGION AS WELL. HOWEVER DID KEEP SOME
LINGERING POPS FOR THE EARLY MORNING HOURS. THIS MAY ALLOW FOR
SOME LIGHT FREEZING RAIN IN THE FAR NORTHERN PORTION OF
FRANKLIN...HILLSBOROUGH AND CHESHIRE COUNTIES. BUT BECAUSE OF THE
LOW CONFIDENCE AND THE FACT THAT HI-RES GUIDANCE KEEPS THIS
PORTION MAINLY DRY DID NOT ISSUE ANY HEADLINES AT THIS TIME.
&&
.SHORT TERM /6 AM FRIDAY MORNING THROUGH FRIDAY NIGHT/...
FRIDAY INTO FRIDAY NIGHT...
ABOVE AVERAGE TEMPERATURES WILL CONTINUE INTO FRIDAY HOWEVER BY
JUST A FEW DEGREES. INITIALLY THOUGHT THAT TEMPS TOMORROW WILL BE
WELL INTO THE 50S AS WE HIT THE MID 40S TODAY. YET LOOKING AT
SOUNDING DATA APPEARS THAT A SUBSTANCE INVERSION WILL BE SET UP
OVER THE REGION. SO WHILE 925 MB TEMPS WILL BE BETWEEN 7C TO
9C...WE MAY BE IN THE LOW TO UPPER 40S ACROSS THE AREA AT THE
SURFACE. THE MAX T GRID FOR TOMORROW MAY BE TO OPTIMISTIC. A STRAY
SHOWER OR TWO MAY MOVE ACROSS THE REGION TOMORROW AS THE BOUNDARY
BEGINS TO SLIDE SOUTHWARD...BUT OVERALL FEEL MAINLY DRY WEATHER
FOR TOMORROW ESPECIALLY SOUTH OF ROUTE 2.
THAT FRONT WILL SLIDE FARTHER SOUTH AND CLOSER TO THE NW COUNTIES ON
FRIDAY NIGHT INCREASING THE POTENTIAL FOR SOME PRECIP AS A LOW
PRESSURE MOVES ALONG THE BOUNDARY. SURFACE TEMPS WILL BE NEAR OR
ABOVE FREEZING FOR THIS TIMEFRAME SO THE POTENTIAL FOR ICING IS
LESS. THE HIGHEST LOCATION FOR PRECIP TO OCCURS WILL BE REGIONS
NORTH OF ROUTE 2 WITH AN ISOLATED CHANCE NORTH OF THE MASS PIKE.
TEMPERATURES OVERNIGHT WILL ONLY DROP SLIGHTLY AS OVERCAST SKIES AND
WEAK WAA WILL LIMIT RADIATIONAL COOLING.
&&
.LONG TERM /SATURDAY THROUGH THURSDAY/...
* UNSETTLED WEATHER OVER THE WEEKEND
* DRIER...COOLER WEATHER EXPECTED EARLY NEXT WEEK
00Z NAM AND GFS ARE MORE PROGRESSIVE THAN THE ECMWF/UKMET/CANADIAN
WITH WAVES OF LOW PRESSURE MOVING ALONG A COLD FRONT STRETCHED
ACROSS NORTHERN NEW ENGLAND FRIDAY NIGHT AND SATURDAY. WITH THE
SUPPORT OF WPC...AM LEANING AWAY FROM THE NAM/GFS SOLUTION FOR THIS
PERIOD OF THE FORECAST. SUNDAY AND BEYOND...MODELS ARE IN
REMARKABLY GOOD AGREEMENT ON THE GENERAL SYNOPTIC SCALE PATTERN
THROUGH THE LONG TERM. WHILE THE MODELS DO SEEM TO BE NARROWING IN
THEIR RANGE OF SOLUTIONS...THERE IS STILL QUITE A BIT OF UNCERTAINTY
WHEN IT COMES TO THE TEMPERATURE PROFILE SATURDAY NIGHT AND SUNDAY.
THESE TEMPERATURE PROFILES...PARTICULARLY THE SURFACE TEMPERATURES
WILL PLAY A BIG ROLE IN PTYPE. AT THIS POINT...LOOKS LIKE ANY
FROZEN/FREEZING PRECIPITATION WILL BE LIMITED TO SOUTHERN NEW
HAMPSHIRE. THE ARCTIC FRONT MOVES THROUGH SOUTHERN NEW ENGLAND LATE
SUNDAY INTO EARLY MONDAY. THEN COOLER...DRIER WEATHER IS FORECAST
TO PERSIST THROUGH CHRISTMAS DAY.
FRIDAY NIGHT THROUGH SATURDAY...LIGHT PRECIPITATION IS POSSIBLE
ACROSS THE NORTHERN ZONES AS LOW PRESSURE MOVES THROUGH NORTHERN NEW
ENGLAND ALONG THE FRONT. QPF FORECASTS ARE LESS THAN A TENTH OF AN
INCH DURING THIS TIME. HOWEVER...LOOKS THAT SURFACE TEMPERATURES IN
SOUTHERN NEW HAMPSHIRE IN PARTICULAR ARE LIKELY TO BE BELOW
FREEZING. SO THERE IS LIKELY TO BE A PERIOD OF FREEZING RAIN IN
THIS AREA. A VERY MINIMAL TEMPERATURE CHANGE CAN MEAN THE
DIFFERENCE BETWEEN ICING AND REGULAR RAIN SO THIS WILL CONTINUE TO
BE MONITORED.
SATURDAY NIGHT THROUGH MONDAY MORNING...WHILE THE MODELS SEEM TO BE
TIGHTENING UP ON THEIR VARYING SOLUTIONS...THERE REMAINS SOME
UNCERTAINTY IN THE SURFACE TEMPERATURE FORECASTS. IT DOES LOOK LIKE
THERE IS POTENTIAL FOR A PERIOD OF FREEZING RAIN SOMEWHERE NORTH OF
ROUTE 2 IN MASSACHUSETTS AND INTO SOUTHERN NEW HAMPSHIRE. THIS SET
OF MODELS TOOK THE COLDER TEMPERATURES A BIT FARTHER NORTH THAN
PREVIOUS MODELS...KEEPING MOST...IF NOT ALL...OF THE CWA OUT OF THE
COLDER TEMPERATURES AND THE FREEZING RAIN. THIS BEING ONE OF THE
FIRST MODEL RUNS TO INDICATE THIS...HAVE USED A BLEND OF THE MODEL
CONSENSUS AND THE PREVIOUS FORECAST FOR THE SURFACE TEMPERATURES.
OTHERWISE...SUNDAY IS EXPECTED TO BE THE WARMEST DAY OF THE FORECAST
WITH TEMPERATURES IN THE 50S SURGING NORTHWARD TO THE MASS PIKE.
THE REST OF MONDAY THROUGH CHRISTMAS DAY...THE ARCTIC FRONT FINALLY
MOVES THROUGH SOUTHERN NEW ENGLAND MONDAY. COLD HIGH PRESSURE
BUILDS IN BEHIND THE FRONT WITH SUBSTANTIALLY COLDER TEMPERATURES
EXPECTED CHRISTMAS EVE AND DAY.
&&
.AVIATION /21Z THURSDAY THROUGH TUESDAY/...
FORECASTER CONFIDENCE LEVELS...
LOW...LESS THAN 30 PERCENT.
MODERATE...30 TO 60 PERCENT.
HIGH...GREATER THAN 60 PERCENT.
NEAR TERM /THROUGH FRIDAY NIGHT/...
WINDS WILL DIE DOWN AFTER SUNSET. HIGH CONFIDENCE VFR
TONIGHT...WITH A LOW POTENTIAL FOR SOME MVFR CONDITIONS IN
SHOWERS AND POSSIBLE ICING ACROSS S NH.
FRIDAY AND FRIDAY NIGHT...
HIGH CONFIDENCE IN VFR TOMORROW WITH SOME SHOWERS APPROACHING THE
NW PORTION OF THE REGION BY LATE FRIDAY NIGHT. COULD BE SOME MVFR
MIXED IN WITH THE SHOWERS ESP ACROSS NORTHERN SITES.
KBOS TAF...HIGH CONFIDENCE IN TAF.
KBDL TAF...HIGH CONFIDENCE IN TAF.
OUTLOOK...SATURDAY THROUGH MONDAY...
SATURDAY...MODERATE CONFIDENCE. MAINLY VFR.
SATURDAY NIGHT THROUGH EARLY MONDAY MORNING...LOW CONFIDENCE.
MVFR/IFR CONDITIONS DEVELOP IN MAINLY RAIN SHOWERS. FREEZING RAIN
IS POSSIBLE MAINLY THROUGH SOUTHERN NEW HAMPSHIRE.
MONDAY AFTERNOON/EVENING/NIGHT...HIGH CONFIDENCE. IMPROVEMENT TO
VFR BEHIND ARCTIC FRONT. WINDS SHIFT FROM SW TO NW.
&&
.MARINE...
FORECASTER CONFIDENCE LEVELS...
LOW...LESS THAN 30 PERCENT.
MODERATE...30 TO 60 PERCENT.
HIGH...GREATER THAN 60 PERCENT.
NEAR TERM /THROUGH FRIDAY NIGHT/...HIGH CONFIDENCE
SW WINDS ARE WEAKENING THIS EVENING AND INTO THE OVERNIGHT. SEAS
WILL ALSO BEGIN TO RELAX AS WELL. ALTERED SCA IN ACCORDANCES.
LIGHT SW FLOW WILL CONTINUE INTO TOMORROW BUT BEGIN TO PULSE UP BY
TOMORROW NIGHT. SEAS WILL LINGER AROUND 5 FT ESP ACROSS THE
SOUTHER OUTER WATERS TOMORROW AND INTO TOMORROW NIGHT...THEREFORE
HAVE EXTENDED THE SCA. DID UNDERCUT SEAS FOR FRIDAY NIGHT AS THEY
SEEMED VERY ROBUST IN A SW FLOW REGIME.
OUTLOOK...SATURDAY THROUGH MONDAY...
SOUTHWESTERLY WINDS WITH PERIODS OF GUSTS UP TO 30 KTS PERSIST
THROUGH MUCH OF THE LONG TERM. WINDS SHIFT TO THE NORTHWEST AS AN
ARCTIC FRONT MOVES ACROSS THE WATERS MONDAY. WAVES BUILD AND
DIMINISH AS WAVES OF LOW PRESSURE MOVE ALONG AN ARCTIC FRONT THROUGH
NORTHERN NEW ENGLAND BUT GENERALLY REMAIN ABOVE 5 FEET ON THE OUTER
WATERS AT LEAST. MUCH OF THIS TIME WILL LIKELY NEED SMALL CRAFT
ADVISORIES UP FOR AT LEAST THE OUTER WATERS...BUT OVERALL CONFIDENCE
IS LOW ON TIMING.
&&
.BOX WATCHES/WARNINGS/ADVISORIES...
CT...NONE.
MA...NONE.
NH...NONE.
RI...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL 8 PM EST THIS EVENING FOR
ANZ231>234-251.
SMALL CRAFT ADVISORY UNTIL 6 AM EST FRIDAY FOR ANZ235-237.
SMALL CRAFT ADVISORY UNTIL 10 PM EST THIS EVENING FOR ANZ250.
SMALL CRAFT ADVISORY UNTIL 7 AM EST SATURDAY FOR ANZ254>256.
&&
$$
SYNOPSIS...DUNTEN
NEAR TERM...DUNTEN
SHORT TERM...DUNTEN
LONG TERM...RLG
AVIATION...DUNTEN/RLG
MARINE...DUNTEN/RLG
AREA FORECAST DISCUSSION
NWS TAMPA BAY RUSKIN FL
215 PM EST THU DEC 19 2013
...WARMER TEMPERATURES ON THE WAY FOR THE UPCOMING WEEKEND...
.SYNOPSIS...
19Z WATER VAPOR AND H4 RAP ANALYSIS SHOWS AN UPPER LEVEL PATTERN
CHARACTERIZED BY DEEP LONGWAVE TROUGHING DIGGING DOWN THE PACIFIC
COAST AND THROUGH THE INTER-MOUNTAIN WEST...FOLLOWED DOWNSTREAM BY A
MORE ZONAL FLOW PATTERN OVER THE CENTRAL AND EASTERN CONUS. THIS
ZONAL FLOW PATTERN EXTENDS SOUTH TO INCLUDE THE NORTHERN GULF OF
MEXICO COAST AND FLORIDA PENINSULA. WV IMAGERY SHOWS A LARGE SWATH
OF VERY DRY AIR IN THE MID/UPPER LEVELS OF THE TROP COVERING THE
FLORIDA PENINSULA AND THE 18/12Z KTBW SOUNDING PROFILE SHOWS THAT
THIS DRY AIR EXTENDS DOWN INTO THE NEAR SURFACE LAYERS AS WELL. THE
KTBW SOUNDING PROFILE FROM THIS MORNING SHOWS AN IMPRESSIVE PW VALUE
OF ONLY AROUND 0.27". THIS VALUE IS NEARLY 2 STANDARD DEVIATIONS
BELOW CLIMATOLOGY FOR THE MIDDLE OF DECEMBER. WITH ALL THE DRY AIR
OVER OUR HEADS...IT IS LITTLE WONDER THAT WE ARE EXPERIENCING MOSTLY
SUNNY SKIES TODAY.
AT THE SURFACE...OUR REGIONS RESIDES TO THE SOUTH OF A 1028MB HIGH
PRESSURE RIDGE CENTERED OVER GA/CAROLINAS. THE GRADIENT IS NOT VERY
STRONG RESULTING IN A WEAK EASTERLY FLOW ACROSS THE PENINSULA.
TEMPERATURES HAVE RECOVERED NICELY FROM THE COOL EARLY MORNING AND
ARE NOW IN THE LOW/MID 70S NORTH ZONES AND MID/UPPER 70S SOUTH.
&&
.SHORT TERM (TONIGHT THROUGH SATURDAY NIGHT)...
TONIGHT...NOT ANTICIPATING ANY ADDITIONAL FROST CONCERNS FOR THE
NATURE COAST. WILL BE ANOTHER COOL NIGHT...BUT NOT NEARLY AS COOL AS
WEDNESDAY NIGHT INTO EARLY THURSDAY MORNING. COOLEST TEMPERATURES
DOWN POTENTIALLY TO THE LOWER/MID 40S WILL BE FOUND ACROSS THE
NORTHERN NATURE COAST...WITH LOWER TO MIDDLE 50S CENTRAL AND MIDDLE
TO UPPER 50S FAR SOUTH.
.FRIDAY AND FRIDAY NIGHT...
THE WARM UP CONTINUES AS THE ZONAL FLOW TRANSITIONS TO UPPER LEVEL
RIDGING OVER THE FL PENINSULA IN PARTIAL RESPONSE TO DIGGING UPPER
TROUGH AND HEIGHT FALLS APPROACHING THE SOUTHERN PLAINS. SURFACE
RIDGE EXITS OFF INTO THE WESTERN ATLANTIC...ALLOWING OUR GRADIENT TO
TIGHTEN SLIGHTLY AND WINDS TO SHIFT FROM EASTERLY TO SOUTHEASTERLY.
THIS SOUTHEASTERLY FLOW WILL BEGIN TO BRING A MORE SIGNIFICANT LOW
LEVEL MOISTURE RETURN TO THE REGION. THE TIGHTER GRADIENT WILL ALLOW
FOR MORE EFFICIENT DIURNAL MIXING AND WITH 850MB TEMPS OF 14-15C
OVERHEAD...DAYTIME TEMPS WILL RISE INTO THE MID/UPPER 70S FAR
NORTH...AND APPROACH OR SURPASS 80 BY A FEW DEGREES FROM THE I-4
CORRIDOR SOUTHWARD. EVEN THROUGH THE GRADIENT WILL BE A BIT
TIGHTER ON FRIDAY...THE STRONGER TERRESTRIAL HEATING MAY ALLOW FOR A
FEEBLE SEA-BREEZE TO DEVELOP. THIS SEA-BREEZE ALONG WITH SOME
MOISTURE RETURN...MAY BE ENOUGH TO FORCE A FEW SHALLOW
SEA-BREEZE/INSTABILITY SHOWERS DURING THE AFTERNOON...MAINLY I-4 AND
SOUTHWARD. IN FACT...SEVERAL OF THE LOCAL HI-RES GUIDANCE MEMBERS
ARE DEVELOPING A FEW "SPOTTY" SHOWERS WITHIN THIS REGIME AND SO WILL
ADD A SLIGHT CHANCE 20% POP TO THE FORECAST FROM HILLSBOROUGH/POLK
COUNTY SOUTHWARD FOR THE AFTERNOON. REGARDLESS...EVEN IF A FEW
SHOWERS DEVELOP...THEY WILL BE BRIEF AND HAVE VERY LIMITED IMPACT TO
ANY OUTDOOR ACTIVITIES. THE ADDED LOW LEVEL MOISTURE WILL RESULT IN
A MUCH WARMER OVERNIGHT FRIDAY NIGHT INTO SATURDAY MORNING WITH MOST
LOCATIONS FAILING TO FALL OUT OF THE 60S...WITH THE EXCEPTION OF
MID/UPPER 50S INLAND TO THE NORTH OF BROOKSVILLE.
SATURDAY AND SATURDAY NIGHT...
MID/UPPER LEVEL RIDGING WILL HOLD ON TO ITS INFLUENCE OVER THE
PENINSULA AS TROUGHING AND ASSOCIATED SURFACE LOW PRESSURE ADVANCE
INTO THE CENTRAL PLAINS/MS VALLEY. THIS INCLEMENT WEATHER WILL NOT
BE IN OUR FORECAST AS THE PROTECTION OF THE UPPER RIDGE KEEPS OUR
WEATHER GENERALLY DRY AND UNSEASONABLY WARM. ALL THE SYNOPTIC
FORCING FOR LIFT AND DEEP LAYER MOISTURE IS STILL WELL REMOVED FROM
OUR REGION THROUGH SATURDAY NIGHT...SO LOOK FOR FAIR CONDITIONS TO
CONTINUE AND TEMPS TO CONTINUE WARMING. HIGHS SATURDAY AFTERNOON
SHOULD REACH THE LOWER 80S FOR MUCH OF THE AREA WITH WARMER SPOTS
FROM TAMPA SOUTHWARD TO FORT MYERS HAVING POTENTIAL TO HIT MID 80S.
LOWS SATURDAY NIGHT HOLD IN THE 60S FOR ALL.
&&
.LONG TERM (SUNDAY THROUGH NEXT WEDNESDAY)...
MODEL GUIDANCE TRENDING MORE IN AGREEMENT WITH THE NEXT SYSTEM TO
DEVELOP OVER THE SOUTHERN PLAINS SATURDAY NIGHT AS AN UPPER LOW
BECOMES NEGATIVELY TILTED OVER THE TX/OK BORDER AND EJECTS OVER
THE SOUTHERN GREAT LAKES ON SUNDAY. MEANWHILE A DEEPENING SURFACE
LOW PRESSURE SYSTEM WILL STRENGTHEN THE SOUTH/SOUTHEAST FLOW OVER
THE EASTERN GULF WATERS SATURDAY NIGHT INTO EARLY SUNDAY AS A COLD
FRONT APPROACHES THE FLORIDA PANHANDLE SUNDAY NIGHT. THE TIMING OF
THE FRONT AND ASSOCIATED RAINFALL CHANCES HAS BEEN PUSHED FORWARD
BY ABOUT 6 HOURS WITH THE LATEST FORECAST PLACING EARLY MONDAY
THROUGH MONDAY NIGHT AS THE PRIMARY WINDOW OF OPPORTUNITY FOR ANY
MEASURABLE RAINFALL TO OCCUR ACROSS THE FORECAST AREA AS THE
SYSTEM PUSHES FROM NORTHWEST TO SOUTHEAST OVER THE PENINSULA.
SOUTHWEST MID TO UPPER FLOW BEHIND THE FRONT WILL PRODUCE SOME
ISENTROPIC UPGLIDE FOR CLOUDINESS AND LINGERING SHOWERS ON
TUESDAY. A BRIEF DECREASE IN CLOUD COVER EXPECTED ON CHRISTMAS DAY
AHEAD OF YET ANOTHER FAST MOVING FRONTAL SYSTEM AND UPPER TROUGH
LATER IN THE WEEK ALTHOUGH MOISTURE DEPTH WILL BE RATHER LIMITED.
&&
.AVIATION...
CLEAR SKIES PERSIST ACROSS THE REGION AS HIGH PRESSURE OVER THE
SOUTHEAST U.S. INFLUENCES THE WEATHER OVER FLORIDA. VFR CONDITIONS
WILL CONTINUE WITH THE EXCEPTION OF MVFR VISIBILITY RESTRICTIONS AT
LAL AND PGD FROM 09Z THROUGH 14Z WITH 4 MILES IN MIST. WINDS WILL
REMAIN LIGHT OUT OF THE EAST NORTHEAST...THEN VEERING TO THE
SOUTHEAST BY THIS EVENING AND INTO FRIDAY.
&&
.MARINE...
HIGH PRESSURE WILL SHIFT EASTWARD INTO THE ATLANTIC THROUGH FRIDAY
ALLOWING WINDS OVER THE EASTERN GULF TO SHIFT FROM EASTERLY TO
SOUTHEASTERLY. A PERIOD OF NEAR CAUTIONARY LEVEL WINDS IS POSSIBLE
TONIGHT OVER THE OFFSHORE WATERS BEFORE DIMINISHING BACK BELOW
HEADLINE CRITERIA DURING FRIDAY. ANOTHER PERIOD OF CAUTIONARY LEVEL
WINDS IS POSSIBLE FRIDAY NIGHT INTO SATURDAY MORNING. A SLOW MOVING
COLD FRONT WILL APPROACH THE EASTERN GULF DURING THE SECOND HALF OF
THE WEEKEND...BUT LIKELY NOT PASS THROUGH THESE WATERS UNTIL THE
EARLY PORTION OF NEXT WEEK.
&&
.FIRE WEATHER...
LOW LEVEL MOISTURE WILL INCREASE OVER THE NEXT COUPLE OF DAYS
KEEPING RELATIVE HUMIDITY ABOVE CRITICAL LEVELS. RAIN CHANCES WILL
REMAIN LOW THROUGH SATURDAY WITH TEMPERATURES WARMING BACK TO ABOVE
NORMAL LEVELS. PATCHY FOG WILL BE POSSIBLE BOTH TONIGHT AND FRIDAY
NIGHT...HOWEVER AT THIS TIME NO SIGNIFICANT AREAS OF DENSE FOG ARE
IN THE FORECAST.
&&
.PRELIMINARY POINT TEMPS/POPS...
TPA 59 81 66 82 / 0 20 10 10
FMY 61 83 65 83 / 0 20 10 10
GIF 55 80 61 82 / 0 20 10 10
SRQ 59 81 65 83 / 0 20 10 10
BKV 49 81 62 83 / 0 10 10 10
SPG 62 79 67 80 / 0 20 10 10
&&
.TBW WATCHES/WARNINGS/ADVISORIES...
FL...NONE.
GULF WATERS...NONE.
&&
$$
SYNOPSIS/SHORT TERM/MARINE/FIRE WX...MROCZKA
AVIATION...WYNN
LONG TERM...LAMARRE
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
317 PM CST THU DEC 19 2013
.DISCUSSION...
UPDATED...316 PM CST
DISCUSSION FOR WEEKEND SYSTEM WILL BE ISSUED SHORTLY...
KEY POINTS: A WINTER STORM WATCH WILL BE ISSUED FOR
LAKE...MCHENRY...WINNEBAGO...LEE...DEKALB AND KANE COUNTIES. IT WILL
BE IN EFFECT FROM SATURDAY EVENING THROUGH SUNDAY EVENING.
A FLOOD WATCH WILL BE IN EFFECT FROM MID SATURDAY MORNING THROUGH
EARLY SUNDAY MORNING FOR FORD...IROQUOIS...NEWTON...JASPER AND
BENTON COUNTIES.
TONIGHT THROUGH FRIDAY NIGHT
UPDATED...1224 PM CST
FRONTAL BOUNDARY IS DRAPED FROM THE CHICAGO METRO AREA WSW TO NEAR
THE QUAD CITIES THIS AFTERNOON. ASCENT IS FORECAST TO INCREASE THIS
EVENING AND TONIGHT ON TOP OF THE BOUNDARY WHICH WILL MEANDER SOME
AS THE SURFACE WAVE LIFTS ACROSS THE REGION. WARM ADVECTION ALOFT
LEAVES LITTLE DOUBT THAT PRECIP WILL MELT ALOFT WITH 3-4C SATURATED
WARM LAYER TEMPS AS FAR NORTH AS THE WI STATE LINE. THE BIG CONCERN
WILL BE SURFACE/GROUND TEMPERATURE TRENDS. TEMPERATURES ARE
EXPECTED TO MOSTLY HOLD STEADY INTO THE LATE EVENING...THEN COLDER
//BELOW FREEZING// SURFACE TEMPS WILL START TO TRICKLE SOUTHEAST
INTO FAR NORTHERN IL AS THE LOW STARTS TO PASS TO OUR SOUTH.
CURRENTLY IT APPEARS THAT ONLY THE FAR REACHES OF THE CWA...
INCLUDING PORTIONS OF OGLE...WINNEBAGO...BOONE...AND MCHENRY
COUNTIES...WILL SEE SURFACE TEMPERATURES FALLING BELOW FREEZING
OVERNIGHT AND WHERE THE CONCERN FOR LIGHT FREEZING RAIN AND LIGHT
ICE ACCUMULATIONS WILL BE. A FREEZING RAIN ADVISORY HAS BEEN ISSUED
FOR THESE COUNTIES...AND EXPECT A GLAZE UP TO A TENTH OF AN INCH OF
ICE FOR THESE AREAS.
BY MID MORNING FRIDAY...TEMPERATURES ARE EXPECTED TO CONTINUE TO
SLOWLY FALL WITH THE LOW DEPARTING EAST. FORCING QUICKLY TAPERS BUT
PERSISTENT LOW LEVEL MOISTURE AND WEAK OMEGA RAISES THE CONCERN FOR
FREEZING DRIZZLE TO SPREAD SOUTH OF THE CURRENT ADVISORY
AREA...PERHAPS AS FAR SOUTH AS THE I-80 CORRIDOR. MID/HIGH LEVEL
MOISTURE WILL BE PRESENT...HOWEVER MID LEVEL DRY LAYER IS EXPECTED
TO INHIBIT SEEDER/FEEDER FROM INTRODUCING ICE INTO THE LOW LEVEL
MOISTURE LAYER...WHICH ONLY HAS TEMPERATURES AS COOL AS -5C.
SURFACE TEMPERATURES WILL BE RIGHT AROUND THE FREEZING MARK. FOR
NOW PLAN ON HIGHLIGHTING AREA WITH AN SPS...AND CANNOT RULE OUT
EXPANSION OF ADVISORY FARTHER SOUTH LATER INTO THE DAY FRIDAY IF
IT APPEARS TEMPERATURES WILL BE COOLER OR IF PRECIP MORE ROBUST.
DEUBELBEISS
DISCUSSION FOR WEEKEND SYSTEM WILL BE ISSUED SHORTLY...
LONG TERM...SUNDAY NIGHT THROUGH THURSDAY...
UPDATED 316 PM CST
SUNDAY NIGHT...
GUIDANCE CONTINUES TO BE CONSISTENT IN DELIVERING A SHOT OF ARCTIC
AIR IN THE WAKE OF THE SIGNIFICANT WEEKEND STORM. A NORTHERN STREAM
TROUGH CURRENTLY NEAR THE NORTH POLE WILL DIG IN OVER THE NORTH
CENTRAL CONUS COUPLED WITH A ~1040 MB HIGH DROPPING SOUTH FROM THE
NORTHERN PLAINS. ALL OF THE SYSTEM SNOWS SHOULD BE OFF TO THE EAST
SUNDAY NIGHT...BUT POSITIVE VORTICITY ADVECTION FROM SHORT WAVES
ROTATING AROUND DEEP UPPER TROUGH COULD SQUEEZE OUT SOME LIGHT SNOW
OR FLURRIES IN THE ARCTIC AIR MASS. THE ECMWF CONTINUES TO BE MOST
BULLISH IN SQUEEZING OUT LIGHT QPF OVER THE AREA. THERE ALSO COULD
BE A BRIEF PERIOD OF FAVORABLE LAKE EFFECT CONDITIONS FOR PORTIONS
OF NW INDIANA DEPENDING ON IF WINDS CAN REMAIN CLOSER TO DUE NORTH
BEFORE BACKING WEST NORTHWEST. TEMPERATURES WILL PLUMMET IN STRONG
COLD ADVECTION BUT PERSISTENT NW WINDS AND CLOUD COVER COULD LIMIT
HOW FAR THEY FALL. WITH THE RAPIDLY FALLING TEMPERATURES SUNDAY
NIGHT...THERE COULD VERY WELL BE A FLASH FREEZE OF ANY REMAINING
MOISTURE ON THE GROUND.
MONDAY...
MAINTAINED A SLIGHT CHANCE OF FLURRIES ON MONDAY MORNING AS THE DEEP
UPPER TROUGH WILL BE OVERHEAD AND IT MAY NOT BE HARD TO SQUEEZE OUT
DENDRITES DESPITE THE COLD DRY AIRMASS. ALSO GUIDANCE INDICATES A
FAIRLY STOUT WAVE FOCUSED INTO THE NORTHEAST CWA AND WISCONSIN...SO
FELT COMFORTABLE WITH THE SLIGHT CHANCE POP FROM GUIDANCE BLEND
INITIALIZATION FOR NORTHEAST IL AND EXTREME NW INDIANA. HIGH
TEMPERATURES MONDAY AND LOWS MONDAY NIGHT WILL BE COLD
EVERYWHERE...BUT HOW COLD WILL DEPEND ON WHICH AREAS MAINTAIN
SUBSTANTIAL SNOWPACK AFTER THE WEEKEND SYSTEM. AT THIS TIME...IT
APPEARS THAT THE NORTHERN CWA WOULD HAVE THE BEST CHANCE. WITH
SURFACE HIGH BEING NEAR OR OVER THE AREA AND NO MORE THAN PARTLY
CLOUDY SKIES EXPECTED...DROPPED LOW TEMPERATURES MONDAY NIGHT FROM
PREVIOUS FORECAST TO 5 TO 10 BELOW WEST OF THE FOX VALLEY. STAYED
MORE CONSERVATIVE IN THE SOUTHERN CWA WHERE LITTLE OR NO SNOW COVER
SHOULD BE LEFT. TO NOTE...THE ECMWF AND GFS WHICH HAVE CLEAR SKIES
HAVE LOWS IN THE COLDEST SPOTS 10 DEGREES COLDER THAN IN FORECAST
GRIDS...WHILE CANADIAN MODEL KEEPS CLOUD COVER AND IS A GOOD DEAL
WARMER.
TUESDAY NIGHT THROUGH THURSDAY...
AFTER A BITTERLY COLD START TO CHRISTMAS EVE DAY...SOUTHWEST WARM
ADVECTION BEHIND TROUGH DEPARTING TO THE EAST WILL ENABLE A DECENT
AFTERNOON TEMPERATURE RECOVERY...BUT STILL WELL BELOW CLIMO. COULD
SEE TEMPERATURES BEING A BIT WARMER THAN CURRENTLY FORECAST IN AREAS
WITHOUT SNOWCOVER. WILL HAVE TO WATCH FOR A NORTHERN STREAM WAVE
BEING A BIT FARTHER SOUTH THAN MODEL CONSENSUS ON CHRISTMAS EVE
NIGHT...BUT WITH ECMWF TRENDING SOUTH...INDICATED A SLIGHT CHANCE OF
LIGHT SNOW NEAR THE WISCONSIN BORDER. THIS FEATURE COULD THEN GO ON
TO RESULT IN AT LEAST SOME LIGHT SNOW OR FLURRIES IN THE AIR FOR THE
ENTIRE AREA ON CHRISTMAS DAY. THIS WOULD BE A CONSOLATION PRIZE FOR
AREAS THAT LOSE THEIR SNOW COVER THIS WEEKEND...BUT FOR AREAS THAT
KEEP AT LEAST 1 INCH OF SNOW ON THE GROUND...A WHITE CHRISTMAS IS
HIGHLY LIKELY. TEMPERATURES WILL MODERATE TO NEAR NORMAL ON
CHRISTMAS DAY...WITH ANOTHER SHOT OF ARCTIC AIR POSSIBLE ON THURSDAY
BEHIND THE CHRISTMAS DAY SYSTEM.
CONFIDENCE IN A WHITE CHRISTMAS FOR AREAS THAT MAINTAIN AT LEAST 1
INCH OF SNOW COVER THIS WEEKEND...HIGH.
RC
&&
.HYDROLOGY...
THERE CONTINUES TO BE AN ELEVATED THREAT OF HEAVY RAINFALL AND
FLOODING THIS WEEKEND. FOR ADDITIONAL DETAILS PLEASE REFER TO THE
FLOOD POTENTIAL OUTLOOK (CHIESFLOT) ISSUED THIS AFTERNOON.
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 20Z...
* LOWERING CIGS AND VSBYS THIS AFTERNOON WITH DRIZZLE LATE.
* IFR CONDITIONS OVERNIGHT WITH CONTINUED DRIZZLE OR RAIN.
* POSSIBLE FREEZING RAIN TOMORROW.
LENNING
//DISCUSSION...UPDATED 18Z...
LOTS OF CONCERNS OVER THE NEXT TWO OR THREE DAYS. A FRONTAL ZONE
PARKED OVER THE AREA WILL REMAIN IN THE NEIGHBORHOOD INTO TOMORROW
MORNING. THIS BOUNDARY WILL PROVIDE THE FOCUS FOR LOWERING CIGS
AND VSBYS THIS AFTERNOON ESPECIALLY AS MOISTURE INCREASES ALOFT.
LATEST TAFS DELAY THE ONSET OF DRIZZLE INTO THIS EVENING BASED ON
LACK OF ANY CURRENT OBSERVATIONS...BUT THIS SHOULD NOT BE THE MAJOR
IMPACT REGARDLESS. WINDS NORTH OF THE FRONT ARE NORTHEAST WHILE
WINDS SOUTH ARE GENERALLY MORE SOUTH OR SOUTHWEST.
SFC TEMPERATURES FALL NORTH OF THE BOUNDARY TODAY AND REMAIN VERY
CLOSE TO FREEZING FOR AN EXTENDED PERIOD TOMORROW. ELECTED TO GO
WITH THE MORE OPTIMISTIC OUTCOME FOR NOW WHICH KEEPS ORD/MDW PRECIP
AS LIQUID ALL DAY FRIDAY...BUT FREEZING RAIN IS A DEFINITE
POSSIBILITY AT ORD/MDW AND A LIKELIHOOD AT RFD. A SATURATED DEEP
WARM LAYER ALOFT WOULD NARROW THE OPTIONS TO RAIN OR FREEZING
RAIN...WITH NEITHER SLEET NOR SNOW APPEARING LIKELY THROUGH AT
LEAST MID DAY FRIDAY BASED ON EXISTING GUIDANCE. FRIDAY AFTERNOON
TOWARD RFD THE WARM LAYER COOLS ALOFT AND THE COLD SURFACE LAYER
DEEPENS...INTRODUCING THE POSSIBILITY OF SLEET IN THAT AREA BUT
STILL NOT TOWARD ORD/MDW.
LENNING
//ORD AND MDW CONFIDENCE...UPDATED 20Z...
* MEDIUM CONFIDENCE IN TIMING AND MAGNITUDE OF LOWER CONDITIONS
THIS AFTERNOON.
* HIGH CONFIDENCE IN RAIN STARTING BY THIS EVENING AND CONTINUING
OVERNIGHT.
* HIGH CONFIDENCE IN LOWERING CIG/VSBY TRENDS TONIGHT AND
TOMORROW.
* MEDIUM CONFIDENCE THAT PRECIP REMAINS MOSTLY LIQUID THROUGH
TOMORROW MORNING AT ORD/MDW.
LENNING
//OUTLOOK FOR ORD/MDW FOR 00Z SATURDAY-12Z THURSDAY...UPDATED 12Z...
FRIDAY NIGHT...CHC RAIN OR SNOW. MVFR TO IFR CIGS.
SATURDAY...A WINTRY MIX OF PRECIP IS EXPECTED DURING THE DAY WITH
RAIN OR FREEZING RAIN OVERNIGHT. MVFR TO IFR CIGS.
SUNDAY...SNOW. MVFR TO IFR CIGS.
MONDAY...FLURRIES IN THE MORNING. VFR.
TUESDAY...VFR.
WEDNESDAY...SCHC OF SNOW DURING THE DAY. MVFR IMPROVING TO VFR.
JEE
&&
.MARINE...
308 PM CST
THERE ARE TWO LOWS SET TO MOVE FROM THE SOUTHERN PLAINS TO THE
LOWER/EASTERN GREAT LAKES REGION THROUGH SUNDAY. THE SECOND ONE WILL
HAVE A LARGER INFLUENCE ON THE WINDS ACROSS THE LAKE...NAMELY
SATURDAY NIGHT THROUGH EARLY MONDAY. AS WINDS TURN
NORTHERLY BEHIND THIS LOW...SPEEDS WILL INCREASE BUT ARE LIKELY TO
REMAIN BELOW GALES ON SUNDAY...ALTHOUGH COULD BE CLOSE ESPECIALLY
IF THE SYSTEM IS DEEPER THAN FORECAST.
IN THE IMMEDIATE NEAR TERM...A FRONT WILL REMAIN DRAPED ACROSS THE
SOUTHERN TWO TO FOUR OPEN WATER ZONES OF LAKE MICHIGAN...WHERE
WINDS WILL BE SOMEWHAT VARIABLE IN SPEED. THIS FRONT WILL INCH
SOUTHWARD FRIDAY MORNING IN THE WAKE OF THE FIRST LOW.
A WINTRY MIX IS EXPECTED ACROSS THE SOUTHERN TWO-THIRDS OF THE
LAKE WITH BOTH SYSTEMS...TONIGHT AND FRIDAY AND AGAIN SATURDAY
NIGHT WHICH SHOULD CHANGE TO ALL SNOW SUNDAY.
IN THE WAKE OF THESE SYSTEMS...STRONG HIGH PRESSURE WILL PASS TO
THE SOUTH OF THE REGION BEFORE LIKELY STRONG SOUTHERLY WINDS TAKE
EFFECT ACROSS THE ENTIRE LAKE SOMETIME CHRISTMAS EVE NIGHT INTO
CHRISTMAS.
MTF
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...FREEZING RAIN ADVISORY...ILZ003-ILZ004-ILZ005-ILZ008...MIDNIGHT
FRIDAY TO NOON FRIDAY.
WINTER STORM WATCH...ILZ003-ILZ004-ILZ005-ILZ006-ILZ008-ILZ010-
ILZ011-ILZ012...6 PM SATURDAY TO 6 PM SUNDAY.
FLOOD WATCH...ILZ033-ILZ039...9 AM SATURDAY TO 6 AM SUNDAY.
IN...FLOOD WATCH...INZ010-INZ011-INZ019...9 AM SATURDAY TO 6 AM
SUNDAY.
LM...SMALL CRAFT ADVISORY...LMZ740...9 AM FRIDAY TO 9 PM FRIDAY.
&&
$$
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[top]
Area Forecast Discussion
National Weather Service Lincoln IL
314 PM CST Thu Dec 19 2013
.DISCUSSION...
ISSUED 253 PM CST Thu Dec 19 2013
Main focus today is on the weekend storm.
SHORT TERM...Tonight through Saturday night.
Morning upper air data displays the digging upper low system in
the southwest US and the upper flow over the plains shifting to
more a east-west flow ahead of the western system. This has
allowed plenty of low level southerly flow over the plains into
the MO/IL region, strengthening the stationary frontal zones over
KS to northern MO to northern IL.
As the wetern system slowly rounds the bottom of the trof, another
upper trof over the northwest plains provides enough pus to get
the arctic cold air to slowly move into IL late tonight and
crossing the rest of IL during the day Friday. Some minor
precipitation in the overrunning of the front late tonight and
through midday Friday, with rain the pcpn type through Friday.
Only on Friday night will there be enough cooling for a mixture of
freezing rain Friday night over the northern half.
On early Saturday morning, the main pcpn begins to develop as the
west coast upper low develops a surface low center that moves up
the now stalled front over the OH Valley. The pcpn moves up into
the southern parts of the CWA Saturday and spreads north through
the day, with a mixture of freezing rain and rain in some areas as
the warm air slowly moves north. Pcpn amounts in the rain are
significant with good lift over the front. Major QPF forecast over
the southeast 1/3, so will continue the flood watch and have added
chc of thunder due to instability seen in the forecast soundings
above the surface boundary level cold air dome. added the possible
thunder Saturday afternoon and evening when best lift is seen.
12z models are a little more to the east than previous runs on the
prog of the surface low, over southern Il to northeast IN this
run. Will have to watch this new trend and see if that affects the
location of the cold air.
Position of the deformation zone and the surface low shows best
snow area in the region along and west of the Illinois River.
Storm total much the same at 3-5.5 inch amounts in this area.
LONG TERM...Sunday through Thursday.
Cold conditions the rule after this system moves through. A
secondary cold frontal system does move through on Wednesday to
Thursday, and so kept the chance of snow with no accumulation.
Goetsch
&&
.AVIATION...
ISSUED 1159 AM CST Thu Dec 19 2013
VFR conditions early this afternoon will deteroriate during
mid/late afternoon and into tonight as low clouds and fog are
expected to develop with ceilings dropping to below 1K ft and
vsbys getting down to 1-3 miles and latest HRRR model ceiling/vsby
parameters support. Also have light rain showers developing later
this afternoon and tonight and continues into Friday morning. A
frontal boundary over nw parts of IL/MO, currently between GBG and
MLI to slowly press se toward the IL river later tonight and
Friday morning. South winds 8-13 kts this afternoon to turn se
this evening and then wsw during Fri morning, except north at PIA
where front passes through. Continue LLWS from I-55 se tonight
into mid morning Friday with 2k ft sw winds of 45-50 kts and
strongest at se TAF sites of CMI & DEC where LLWS could linger
most of Friday morning.
07
&&
.ILX WATCHES/WARNINGS/ADVISORIES...
FLOOD WATCH from late Friday night through late Saturday night
FOR ILZ044>046-052>057-061>063-066>068-071>073.
&&
$$
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
1201 PM CST THU DEC 19 2013
.DISCUSSION...
328 AM CST
TODAY THROUGH TONIGHT...
OVER THE NEXT SEVERAL DAYS WILL FEATURE A METEOROLOGICAL ROLLER
COASTER...WITH A WIDE RANGE OF TEMPERATURES ABOVE/BELOW
FREEZING...PRECIPITATION CHANGING FROM FROZEN TO LIQUID AND BACK TO
FROZEN...MELTING SNOWPACK WITH POTENTIAL FOR ABUNDANT RAINFALL ON
FROZEN GROUND AND CONSIDERABLE ICE ON AREA STREAMS LEADING TO
POSSIBLY HYDRO CONCERNS. TO FURTHER COMPOUND THE HYDRO CONCERNS WILL
BE THAT IF ICE BREAKS UP ON STREAMS IT MAY EASILY BECOME LOCKED BACK
UP AS SUB-FREEZING AIR RETURNS FOR EARLY NEXT WEEK.
MAIN ITEM ON THE AGENDA FOR TODAY...CAN FOG DEVELOP AND HOW WARM
WILL SFC TEMPS BECOME THIS AFTN. A WEAK SFC LOW NORTHEAST OF THE
STRAITS OF MACKINAW CONTINUES TO PUSH EAST WITH A TRAILING FRONTAL
BOUNDARY STRETCHING WEST THROUGH CENTRAL WISC INTO CENTRAL IOWA.
BROAD ANTI-CYCLONIC FLOW OVER THE CANADIAN PRAIRIES IS SEEPING
SOUTH...AND EXPECTED TO SHARPEN THE BAROCLINIC ZONE ALONG THE
STALLED FRONTAL BOUNDARY.
MAIN CONCERNS FOR TODAY WILL REVOLVE AROUND WHEN/IF FOG CAN
DEVELOP...ALONG WITH STEADILY MOISTENING OF THE NEAR SFC ENVIRONMENT
AS ADDTL MOISTURE ADVECTS NORTH FROM A NEARLY +3 SIGMA V-WIND
COMPONENT INTO AN ABNORMALLY HIGH PWAT REGION OF NORTHERN
IL/NORTHWEST IN. SOUNDINGS HAVE STEADILY OVERDONE MOISTURE...AND
PRESENT T/TD DEPRESSIONS IN PLACES REMAIN IN EXCESS OF 5 DEG TO AS
MUCH AS 10 DEG...WHICH PLACES LESS CONFIDENCE ON THE DEVELOPMENT OF
FOG FOR A FEW HOURS. THERE ARE A FEW LOCATIONS THAT HAVE SOME PATCHY
FOG THIS MORNING...HOWEVER THE COVERAGE IS LIKELY GOING TO REMAIN
LOW. THERMAL BOUNDARY EXISTS FROM MOLINE EAST THROUGH
GARY/VALPO...TO THE NORTH TEMPS ARE IN THE TEENS/20S AND SOUTH THEY
ARE IN THE MID/UPR 30S.
GUIDANCE HAS CONSOLIDATED AROUND LATE MORNING WITH THE BEGINNING
TIMEFRAME FOR DRIZZLE/LGT RA...SO HAVE PUSHED BACK TIMING UNTIL
THEN. TEMPS NORTH OF I-88 WILL LIKELY REMAIN IN THE MID 30S TDY
WHILE SOUTH OF THIS LINE TEMPS SHUD WARM TO ARND 40.
THEN FOR TONIGHT IT APPEARS THE SETUP CONTINUES TO FAVOR FREEZING
RAIN...MAINLY FOR AREAS ALONG AND WEST OF LASALLE TO WAUKEGAN. WEAK
LOW WILL LIFT NORTHEAST ALONG THE BAROCLINIC ZONE WITH THE DEEPER
MOISTURE PEELING OFF TO THE NORTHEAST...WHICH WILL LEAVE IN ITS WAKE
A BAGGY ENVIRONMENT. WITH THE LACK OF LIFT...AND TEMPS HOVERING ARND
FREEZING TO JUST BELOW FREEZING...AND THERMAL PROFILES SHOWING A
CONSIDERABLE WARM LAYER...ANY PRECIP WILL LIKELY BE LGT AND FREEZING
RAIN OR FREEZING DRIZZLE. EAST OF THE AFOREMENTIONED LINE SFC TEMPS
SHUD HOLD RIGHT AT FREEZING OR JUST ABOVE...KEEPING PRECIP IN LIQUID
FORM. NONETHELESS WITH THE GROUND STILL FROZEN FROM THE PAST FEW
WEEKS...UNTREATED SURFACES MAY STILL HAVE SOME SLICK SPOTS.
CONFIDENCE IN TEMPS...MEDIUM/HIGH.
CONFIDENCE IN FZRA TONIGHT WEST OF LASALLE TO WAUKEGAN...HIGH.
CONFIDENCE IN AREAS EAST OF THIS LINE SEEING FZRA...MEDIUM.
FRIDAY THROUGH SUNDAY...
THE FORECAST AREA WILL CONTINUE TO BE IN A RATHER MOIST
ENVIRONMENT...WITH LINGERING LLVL/MID-LVL MOISTURE IN THE WAKE OF
THE DEPARTING SFC LOW...THUS FRI MORNING MAY CONTINUE TO SEE SPOTTY
FZRA/FZDZ OR LGT SN FOR THE FAR NW. FURTHER EAST TEMPS WILL LIKELY
REMAIN ABOVE FREEZING AND AGAIN ANY PRECIP WILL BE LGT AND RAIN.
SFC RIDGE ACROSS THE NORTHERN PLAINS/UPPER MIDWEST WILL SAG SOUTH
AND BECOME ORIENTED FROM THE CENTRAL PLAINS NORTHEAST TO WESTERN
LAKE SUPERIOR...PLACING THE CONTINUED BAROCLINIC ZONE SOMEWHERE
ACROSS THE CWFA AND BECOMING ORIENTED FROM SW TO NE PERHAPS FROM
LASALLE IL TO KENOSHA WI. TEMPS WILL REMAIN NEARLY STEADY THROUGHOUT
THE DAY IN THE LOW/MID 30S TO PSBLY ARND 40 ACROSS THE FAR SE CWFA.
FOCUS BEYOND FRI WILL BE ON THE HIGHLY ANTICIPATED MID-LVL VORT
MAX...PROGGED TO SLIDE EAST ACROSS THE SOUTHERN ROCKIES INTO WEST
TEXAS FRI NGT. DOWNSTREAM OF THIS FEATURE THE RIDGE WILL BECOME
PARKED ACROSS THE WESTERN ATLANTIC/SOUTHEAST COAST...ALLOWING A
CONSIDERABLE PLUME OF MOISTURE TO ADVECT NORTH THROUGH THE OZARKS
INTO THE TENN/OHIO VALLEY. GUIDANCE HAS BEEN CONSISTENT OVER THE
PAST FEW DAYS WITH AN ABUNDANCE OF PRECIP THROUGHOUT THIS
REGION...THE UNCERTAINTY IS ON HOW FAR NORTH IT WILL STRETCH.
CYCLOGENESIS CONTINUES TO BE PROGGED OVER CENTRAL TEXAS...AND
QUICKLY LIFT NORTH/NORTHEAST SAT TO FAR SOUTHERN IL BY EARLY SUN
MORNING. MODELS WILL LIKELY CONTINUE TO DEMONSTRATE CORRECTIONS OR A
WOBBLE ON THE PRECISE SFC LOW PATH...LARGELY IN PART FROM THE
PRESENT SNOW COVER/BARE GROUND LINE.
AS FOR P-TYPE SAT/SUN...THIS TOO CONTINUES TO EVOLVE WITH THE LATEST
FORECAST SOLUTIONS. THE EC/GFS HAVE SLIGHTLY DIFFERENT IDEAS ON THE
PATH OF THE SYSTEM...WHICH WILL DICTATE WHERE RAIN AND/OR SNOW WILL
FALL. NOT TO MENTION HOW MUCH OF EACH. AT THIS JUNCTURE HAVE OPTED
TO MAINTAIN THE CURRENT THINKING RATHER THAN FLIP-FLOPPING THE
FORECAST...GIVEN THE UNCERTAINTY THAT REMAINS. SOME COOLING DOES
APPEAR TO TAKE SHAPE FOR THE NORTH/NORTHWEST CWFA SAT...WHICH COULD
KEEP TEMPS SUB-FREEZING OR AT FREEZING THROUGHOUT THE DAY SAT.
850MB LOW IS PROGGED TO LIFT NORTHEAST ACROSS THE CWFA...CURRENTLY
SHAPING UP TO BE ALONG A PONTIAC TO CHICAGO LINE. THIS WOULD LIKELY
DISPLACE THE DEFORMATION ZONE TO THE NORTHWEST ACROSS THE FAR NW
CWFA SAT EVENING/EARLY SUN. THERE HAS ALSO BEEN CONSISTENCY IN A DRY
WEDGE LIFTING NE IN THE WAKE OF THE SFC LOW...WHICH COULD FEATURE A
PERIOD OF DRY WX SUN MORNING FOR THE FAR SE CWFA.
FRONTAL BOUNDARY SWEEPS EAST ACROSS THE FORECAST AREA BY MIDDAY
SUN...WITH FLOW BECOMING UNIFORM FROM THE NORTH/NORTHWEST. 500MB
TROUGH AXIS THEN PUSHES OVER THE REGION...WITH ANY LINGERING PRECIP
FALLING AS LGT SNOW SUN AFTN/EVE SETTING THE STAGE FOR LAKE EFFECT
DOWNSTREAM OF LAKE MICHIGAN.
CONFIDENCE IN TEMPS...MEDIUM/HIGH.
CONFIDENCE IN SNOW REMAINING NW OF LASALLE TO WAUKEGAN THRU SAT
NGT...MEDIUM/HIGH.
MONDAY THROUGH CHRISTMAS DAY...
ENSEMBLES HAVE REMAINED RATHER CONSISTENT WITH A SIMILAR SETUP OF
TWO RIDGES INFLUENCING THE WEATHER PATTERN. ONE BEING PARKED ACROSS
THE EASTERN PACIFIC...THE OTHER OVER THE WESTERN ATLANTIC. THIS
SETUP ALLOWS FOR THE CONTINUED TROUGHING ACROSS THE CENTER OF THE
COUNTY INCLUDING THE GREAT LAKES REGION. HOWEVER BY CHRISTMAS DAY
THESE FEATURES ARE PROGGED TO WEAKEN...WITH MID-LVL FLOW OVER THE
CENTRAL CONUS FLATTENING OUT.
THERE IS SOME INDICATIONS THAT BEYOND CHRISTMAS DAY A HIGH AMPLITUDE
RIDGE WILL BEGIN TO DEVELOP ACROSS FAR WESTERN CANADA...AND COULD
EVENTUALLY DEVELOP A DOWNSTREAM TROUGH YET AGAIN FOR THE GREAT LAKES
REGION LATER NEXT WEEK.
MON/TUE OPERATIONAL SOLUTIONS HAVE A BROAD SFC RIDGE MOVING EAST
ACROSS THE GREAT LAKES REGION AS THE MID-LVL TROUGH AXIS PIVOTS
EAST. THERMAL TROUGH ALOFT WILL LIKELY KEEP TEMPS IN THE TEENS/LOW
20S MON THEN BEGIN TO MODERATE INTO THE 20S BY TUE. WITH THE
AFOREMENTIONED DISCUSSION ON A FLATTENING FLOW...TEMPS MAY RETURN TO
SEASONAL CONDITIONS OR LOW 30S BY CHRISTMAS DAY. MODELS ARE
INDICATING A WEAK MOISTURE STARVED BOUNDARY ARRIVING ACROSS THE
REGION FOR CHRISTMAS DAY...COULD PROVIDE A FEW FLURRIES/LGT SNOW.
CONFIDENCE IN EXTENDED PERIODS...HIGH.
BEACHLER
&&
.HYDROLOGY...
THERE CONTINUES TO BE AN ELEVATED THREAT OF HEAVY RAINFALL AND
FLOODING THIS WEEKEND. FOR ADDITIONAL DETAILS PLEASE REFER TO THE
FLOOD POTENTIAL OUTLOOK (CHIESFLOT) ISSUED THIS AFTERNOON.
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 18Z...
* LOWERING CIGS AND VSBYS THIS AFTERNOON WITH DRIZZLE POSSIBLE.
* IFR CONDITIONS OVERNIGHT WITH CONTINUED DRIZZLE OR RAIN.
* POSSIBLE FREEZING RAIN TOMORROW.
LENNING
//DISCUSSION...UPDATED 18Z...
LOTS OF CONCERNS OVER THE NEXT TWO OR THREE DAYS. A FRONTAL ZONE
PARKED OVER THE AREA WILL REMAIN IN THE NEIGHBORHOOD INTO TOMORROW
MORNING. THIS BOUNDARY WILL PROVIDE THE FOCUS FOR LOWERING CIGS
AND VSBYS THIS AFTERNOON ESPECIALLY AS MOISTURE INCREASES ALOFT.
LATEST TAFS DELAY THE ONSET OF DRIZZLE INTO THIS EVENING BASED ON
LACK OF ANY CURRENT OBSERVATIONS...BUT THIS SHOULD NOT BE THE MAJOR
IMPACT REGARDLESS. WINDS NORTH OF THE FRONT ARE NORTHEAST WHILE
WINDS SOUTH ARE GENERALLY MORE SOUTH OR SOUTHWEST.
SFC TEMPERATURES FALL NORTH OF THE BOUNDARY TODAY AND REMAIN VERY
CLOSE TO FREEZING FOR AN EXTENDED PERIOD TOMORROW. ELECTED TO GO
WITH THE MORE OPTIMISTIC OUTCOME FOR NOW WHICH KEEPS ORD/MDW PRECIP
AS LIQUID ALL DAY FRIDAY...BUT FREEZING RAIN IS A DEFINITE
POSSIBILITY AT ORD/MDW AND A LIKELIHOOD AT RFD. A SATURATED DEEP
WARM LAYER ALOFT WOULD NARROW THE OPTIONS TO RAIN OR FREEZING
RAIN...WITH NEITHER SLEET NOR SNOW APPEARING LIKELY THROUGH AT
LEAST MID DAY FRIDAY BASED ON EXISTING GUIDANCE. FRIDAY AFTERNOON
TOWARD RFD THE WARM LAYER COOLS ALOFT AND THE COLD SURFACE LAYER
DEEPENS...INTRODUCING THE POSSIBILITY OF SLEET IN THAT AREA BUT
STILL NOT TOWARD ORD/MDW.
LENNING
//ORD AND MDW CONFIDENCE...UPDATED 18Z...
* MEDIUM CONFIDENCE IN TIMING AND MAGNITUDE OF LOWER CONDITIONS
THIS AFTERNOON.
* HIGH CONFIDENCE IN RAIN STARTING BY THIS EVENING AND CONTINUING OVERNIGHT.
* HIGH CONFIDENCE IN LOWERING CIG/VSBY TRENDS TONIGHT AND
TOMORROW.
* MEDIUM CONFIDENCE THAT PRECIP REMAINS MOSTLY LIQUID TOMORROW AT ORD/MDW.
LENNING
//OUTLOOK FOR ORD/MDW FOR 00Z SATURDAY-12Z THURSDAY...UPDATED 12Z...
FRIDAY NIGHT...CHC RAIN OR SNOW. MVFR TO IFR CIGS.
SATURDAY...A WINTRY MIX OF PRECIP IS EXPECTED DURING THE DAY WITH
RAIN OR FREEZING RAIN OVERNIGHT. MVFR TO IFR CIGS.
SUNDAY...SNOW. MVFR TO IFR CIGS.
MONDAY...FLURRIES IN THE MORNING. VFR.
TUESDAY...VFR.
WEDNESDAY...SCHC OF SNOW DURING THE DAY. MVFR IMPROVING TO VFR.
JEE
&&
.MARINE...
414 AM CST
LOW PRESSURE IS OVER THE NORTHERN LAKES THIS MORNING AND IT WILL
WEAKEN AS IT SHIFTS EAST. A COLD FRONT PUSHES DOWN THE LAKE TODAY
AND STALLS OVER SOUTHERN LAKE MICHIGAN THIS AFTERNOON AND
OVERNIGHT. WINDS TURN NORTH AND THEN EAST BEHIND THE FRONT AND
INCREASE TO 15 TO 25 KT...WITH SOUTH WINDS 10 TO 20 KT SOUTH OF THE
FRONT. WINDS FINALLY BECOME UNIFORMLY NORTH TO NORTHEAST FRIDAY
MORNING. AS SUCH THE 15 TO 25 KT WINDS MOVE ALONG THE NEARSHORE
WATERS NORTH OF CALUMET HARBOR EARLY FRIDAY MORNING. HAZARDOUS
WAVES ARE ALSO LIKELY FRIDAY AND POSSIBLY INTO FRIDAY NIGHT. A
SMALL CRAFT ADVISORY WILL LIKELY BE NEEDED...BUT DID NOT ISSUE ONE
AT THIS TIME. WINDS AND WAVES WILL BE JUST ON THE CUSP OF SMALL
CRAFT CRITERIA...SO DECIDED TO HOLD OFF JUST A LITTLE LONGER ON THE
NEXT SMALL CRAFT ADVISORY.
THE NEXT LOW PASSES SOUTH OF THE LAKE FRIDAY AND IT WEAKENS AS IT
CONTINUES OFF TO THE NORTHEAST. THE GRADIENT WEAKENS AS DO WINDS
WITH EAST WINDS EXPECTED FRIDAY NIGHT INTO SATURDAY. HIGH PRESSURE
PASSES TO THE NORTHWEST OF THE LAKE SATURDAY...THEN THE NEXT LOW
PUSHES UP THE OHIO RIVER VALLEY SATURDAY NIGHT INTO SUNDAY. WINDS
INCREASE AND BECOME NORTH SUNDAY THEN NORTHWEST SUNDAY NIGHT. A
SMALL CRAFT ADVISORY WILL LIKELY BE NEEDED SATURDAY NIGHT THROUGH
MONDAY FOR HIGH WINDS AND WAVES. OVER THE OPEN WATERS...WINDS TO 30
KT ARE EXPECTED. WINDS TURN WEST BEHIND THE LOW MONDAY NIGHT AND
CONTINUE TO WEAKEN AS HIGH PRESSURE MOVES OVER THE WESTERN LAKES
MONDAY NIGHT. INCREASING SOUTH WINDS ARE EXPECTED TUESDAY BETWEEN
THE DEPARTING LOW AND LOW PRESSURE SYSTEM OVER ONTARIO.
JEE
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...FREEZING RAIN ADVISORY...ILZ003-ILZ004-ILZ005-ILZ008...MIDNIGHT
FRIDAY TO NOON FRIDAY.
IN...NONE.
LM...NONE.
&&
$$
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Area Forecast Discussion
National Weather Service Lincoln IL
1159 AM CST Thu Dec 19 2013
.DISCUSSION...
ISSUED 1050 AM CST Thu Dec 19 2013
Will update the forecast to go with milder highs in the mid to
upper 40s today, with some lower 50s over sw counties where less
snow cover of 1 inch or less from Jacksonville sw and from I-70 se.
No fog or low clouds developing yet over central IL but HRRR does
develop some fog and especially low clouds over northern half of
CWA during the afternoon due to snow melt and increase snow melt
and winds lighter over the IL river valley. So will continue
patchy fog and slight chance of light rain showers during mid/late
afternoon from I-72 north this afternoon with low clouds also
expected to develop. A cold front over far nw IL into nw MO will
press slowly se toward Galesburg during the afternoon and evening
and this will help develop some light rain showers. Temps looks
warm enough through this evening for precipitation to stay all
rain even over Knox and Stark counties.
07
&&
.AVIATION...
ISSUED 1159 AM CST Thu Dec 19 2013
VFR conditions early this afternoon will deteroriate during
mid/late afternoon and into tonight as low clouds and fog are
expected to develop with ceilings dropping to below 1K ft and
vsbys getting down to 1-3 miles and latest HRRR model ceiling/vsby
parameters support. Also have light rain showers developing later
this afternoon and tonight and continues into Friday morning. A
frontal boundary over nw parts of IL/MO, currently between GBG and
MLI to slowly press se toward the IL river later tonight and
Friday morning. South winds 8-13 kts this afternoon to turn se
this evening and then wsw during Fri morning, except north at PIA
where front passes through. Continue LLWS from I-55 se tonight
into mid morning Friday with 2k ft sw winds of 45-50 kts and
strongest at se TAF sites of CMI & DEC where LLWS could linger
most of Friday morning.
07
&&
.PREV DISCUSSION...
ISSUED 311 AM CST Thu Dec 19 2013
High pressure sliding to the southeastern corner of the country as
a cold front slowly approaches the Midwest. A vigorous wave is
digging in over the southwest and translating into more
southwesterly flow over the region. Temperatures slowly increasing
as the airmass modifies with persistent moisture and warm air
advection. Cold front on the way to move through the area late
tonight and tomorrow morning...eventually stalling invof the Ohio
River Valley. Initial fropa less of an issue, with predominantly
rain for ILX. However, the front will provide a focus for precip
in the southeast...and a path to follow for the next wave ejecting
out of the southwest. Models have been very inconsistent with
track and thermodynamics...and are starting to waiver in the
strength overall. That being said, the trend to a more northerly
track is reflected in the forecast.
SHORT TERM...Today and Tonight...
Warmer as southerly winds usher in temps into the 40s. Overnight
expected to remain mostly above freezing as well. Pops return to
the forecast late this afternoon in the extreme NW as rain makes
its way into Central Illinois. Rain chances continue through the
overnight with the front as the winds slowly shift to
northwesterly behind the front and cooler air filters in. Cold air
not moving in very quickly however as the boundary is relatively
weak/the thermal gradient is less significant. For now, the
initial front is dominated by rain. Problems creep in after
midnight tomorrow night as temperatures finally drop and the
precip changes over to freezing rain for the northern half of the
state.
LONG TERM...Saturday through Wednesday...
Models still a problem, lacking continuity and consistency. Trend
to the north is pronounced enough to be reflected however. This
same trend broadens the developing warm sector and reduces the
coldest air. Ice/freezing rain confined mostly to NW of the
Illinois River Valley for Saturday morning, though a transition to
liquid will likely fall between the valley and the I-55 corridor.
Freezing rain in the NW and rain in the SE will continue through
the afternoon and evening before making the transition over to
snow for after midnight and Sunday. All this precip type/wintry
mix determination a low confidence forecast and likely to shift
with subsequent model runs. However, confidence is increasing on
the prolonged and heavy rain event setting up btwn I-70 corridor
and the Ohio River Valley. 2-3 inches of rainfall from Friday
night through Sunday morning will result in an increased flood
risk, particularly with partially frozen ground...already
saturated from recent snowmelt. Flood watch issued with the
forecast from Christian County to Vermilion County and points SE.
Monday bitterly cold on the back side of this system with highs in
the teens... and Monday night sinking into the single digits with light
winds and very little cloud cover. Remains of the forecast left to
the AllBlend for temps, and dry as high pressure returns to the
Midwest until the next systems arrival late Wednesday.
HJS
&&
.ILX WATCHES/WARNINGS/ADVISORIES...
FLOOD WATCH from late Friday night through late Saturday night
FOR ILZ044>046-052>057-061>063-066>068-071>073.
&&
$$
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
1240 PM EST THU DEC 19 2013
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 452 AM EST THU DEC 19 2013
A 1005MB LOW PRESSURE OVER EASTERN LAKE SUPERIOR CONTINUES TO
QUICKLY SLIDE EAST THIS MORNING...AS AN ASSOCIATED 925/850MB TROUGH
EXITS THE UPPER GREAT LAKES REGION. THIS QUICK DEPARTURE HAS LED TO
WINDS TURNING TO THE NORTHWEST OVER THE WESTERN LAKE AND AN AREA OF
MVFR CLOUDS (PICKED UP WELL IN THE RH FIELDS OF THE RAP ANALYSIS)
DROPPING SOUTHEAST ACROSS WESTERN AND NORTH CENTRAL UPPER MICHIGAN.
CEILINGS HAVE BEEN LOWERING FAIRLY STEADILY AT KCMX OVER THE LAST
COUPLE OF HOURS AND WITH THE RAP INDICATING 925MB TEMPS FALLING TO
-10C OVER WESTERN LAKE SUPERIOR...HAVE BEEN SEEING INDICATIONS ON
SATELLITE THAT LAKE EFFECT CLOUDS HAVE BEEN DEVELOPING. HAVEN/T
SEEN ANY PRECIPITATION NOTED AT CMX OR ON WEBCAMS OVER THE
KEWEENAW...BUT WOULD EXPECT LIGHT SNOW OR FREEZING DRIZZLE TO START
SHORTLY.
FOR TODAY...WITH THE LOW SLIDING EAST EARLY THIS MORNING AND THE
MAIN SHORTWAVE TO THE NORTHWEST OF LAKE SUPERIOR JUST BRUSHING THE
NORTHERN PART OF THE LAKE...THERE APPEARS TO BE LITTLE SYNOPTIC
FORCING ACROSS THE AREA FOR MUCH OF THE DAY. OTHER THAN THE
POTENTIAL FOR A BRIEF STRONGER SHOWERS MOVING ACROSS EASTERN LAKE
SUPERIOR WITH THE FRONT AND WIND SHIFT TO THE NORTHWEST.
OTHERWISE...THE COLDER AIR DROPPING SOUTHEAST ACROSS LAKE SUPERIOR
(925MB TEMPS FALLING TO -13C BY 00Z FRIDAY) WILL LEAD TO AN INCREASE
IN LIGHT LAKE EFFECT PRECIPITATION THIS MORNING. WITH A HIGH
PRESSURE RIDGE LOCATED JUST TO THE NORTH OF LAKE SUPERIOR TODAY
WILL LEAD TO WINDS VEERING TO THE NORTH-NORTHEAST THROUGH THE DAY.
THIS ANTI-CYCLONIC FLOW ACROSS THE LAKE WON/T BE TOO FAVORABLE FOR
LAKE EFFECT...WHICH WILL COMBINE WITH THE STRONG POCKET OF DRY
AIR ABOVE 850MB (INVERSION HEIGHTS AROUND 4KFT) ASSOCIATED WITH THE
HIGH TO KEEP ANY PRECIPITATION LIGHT. THERE IS SOME CONCERN ON SOME
FREEZING DRIZZLE MIXING WITH THE SNOW FOR THE FIRST PART OF THE
MORNING NEAR LAKE SUPERIOR AND HAVE TRIED TO FOLLOW THE TIMING OF
THE 925MB AROUND -9/-10C TO MARK THE TRANSITION TO ALL SNOW THIS
MORNING. AS FOR AMOUNTS...THINK A DUSTING TO AN INCH SEEMS
REASONABLE...WITH THE MOST IN THE FAVORED NORTH-NORTHEAST UPSLOPE
LOCATIONS OF NORTH CENTRAL UPPER MICHIGAN.
FOR TONIGHT...A QUICK MOVING DISTURBANCE WILL MOVE ACROSS UPPER
MICHIGAN IN THE WESTERLY FLOW ALOFT. IN ADDITIONS TO THE
SHORTWAVE...THE UPPER GREAT LAKES REGION WILL BE UNDER THE
FAVORABLE RIGHT REAR OF A 160KT UPPER JET AND PROVIDE DECENT
SUPPORT ALOFT FOR A SWATH OF SNOW TO MOVE ACROSS THE CWA. AT THE
SURFACE...A WEAK INVERTED TROUGH DOES LOOK TO DEVELOP OVER CENTRAL
UPPER MICHIGAN...WITH WILL HELP KEEP THE LOW LEVEL (950-900MB) FLOW
FOCUSED OVER NORTH CENTRAL UPPER MICHIGAN TO PROVIDE LAKE
ENHANCEMENT. MODELS HAVE BEEN FAIRLY CONSISTENT ON THE SWATH OF
SNOW/QPF MOVING EAST ACROSS THE CWA AROUND MID EVENING AND THEN
QUICKLY DEPARTION ABOUT HALFWAY THROUGH THE OVERNIGHT HOURS.
A GENERAL CONSENSUS IS FOR 0.1-0.15IN OF QPF MOVING ACROSS
CENTRAL/SOUTHERN UPPER MICHIGAN TONIGHT (ONLY 0.05-0.10 OVER THE
KEWEENAW) AND HAVE FOLLOWED THAT FOR THE SYNOPTIC QPF. ONE ITEM TO
NOTE IS THAT THAT DRY POCKET OF AIR BETWEEN 850-700MB WILL NEED TO
BE OVERCOME BEFORE THE SNOW CAN START. FORTUNATELY...THE FLOW IN
THAT LAYER IS FAIRLY LIGHT AND SHOULD ALLOW IT TO QUICKLY MOISTEN.
THEN...WITH THAT FAVORABLE NORTHEAST UPSLOPE AND LAKE ENHANCED
FLOW...ADJUSTED VALUES UP OVER THE HIGHER TERRAIN OF THE NORTH
CENTRAL U.P. FROM THE HURON MOUNTAINS THROUGH NEGAUNEE/GWINN. THE
TRICKY PART IN THE FORECAST COMES FROM PINNING DOWN SNOW RATIOS.
WITH MUCH OF THE BROAD MID LEVEL FGEN FOCUSED WITHIN THE
DGZ...WOULD EXPECT THERE TO BE A 3-4HR PERIOD OF SNOW RATIOS AROUND
20-1 BEFORE A DOWNWARD TREND ONCE THE BETTER FORCING DEPARTS. COBB
OUTPUT AWAY FROM THE LAKE ENHANCEMENT SUPPORTS THAT IDEA AND WITH
THAT DGZ LAYER BEING FAIRLY ISOTHERMAL...HAVE CONTINUED THOSE
RATIOS IN THE FORECAST. IN THE LAKE ENHANCEMENT AREA...THERE ARE
HINTS OF BETTER FORCING BELOW THE DGZ THAT COULD LEAD TO SLIGHTLY
LOWER RATIOS...BUT WONDERING IF THAT MAY BE A TOUCH TOO LOW AS IT
BEING ABOUT 1KFT HIGHER IT WOULD BE IN THE DGZ. THUS...OPTED TO
KEEP THE HIGHER RATIOS IN THE LAKE/TERRAIN ENHANCED AREAS TOO. THIS
LEADS TO A WIDESPREAD 1-3 INCH SNOWFALL FOR MUCH OF UPPER
MICHIGAN...WITH SOME LOCALLY HIGHER AMOUNTS IN THE NORTH CENTRAL.
DEBATED AN ADVISORY FOR MARQUETTE COUNTY FOR AN AVERAGE MORE LIKE
2-4INCHES...BUT OPTED TO DO AN SPS FOR THE ENTIRE CWA INSTEAD.
THERE WERE 2 MAIN REASONS FOR NOT GOING WITH AN ADVISORY.
ONE...SINCE THE MAIN SNOW WILL LIKELY FALL BETWEEN 10PM AND
3AM...THE IMPACTS ON THE POPULATION WILL BE LOWER AND THERE SHOULD
STILL BE ENOUGH TIME TO TREAT THE ROADS BEFORE THE MORNING COMMUTE.
THE SECOND IS A COMBINATION ON UNCERTAINTY WITH SNOW RATIOS AND QPF
AMOUNTS...WHICH BEING OFF BY A COUPLE HUNDREDTHS AT 20 TO 1 COULD
QUICKLY LOWER AMOUNTS. GOING FORECAST WAS FAIRLY SIMILAR TO THE 00Z
NAM AND LOCAL WRF-ARW RUNS...BUT THE 06Z NAM THAT JUST ARRIVED HAS
DROPPED QPF AMOUNTS IN THE ENHANCED AREAS BY 0.07IN. THUS...FELT
HOLDING OFF ON A BORDERLINE ADVISORY WAS WARRANTED AND WILL PASS
CONCERNS TO DAYSHIFT.
.LONG TERM...(FRIDAY THROUGH WEDNESDAY)
ISSUED AT 452 AM EST THU DEC 19 2013
ANY REMAINING MOISTURE AND LIFT RAPIDLY MOVES SOUTH AND EAST ON
FRIDAY MORNING AS A WEAK RIDGE AXIS BUILDS ACROSS LAKE SUPERIOR.
THIS SHOULD ALLOW ANY SNOW SHOWERS OFF THE LAKE TO END QUICKLY IN
THE MORNING. THERE IS A HINT OF LINGERING DEEP MOISTURE ACROSS FAR
SOUTHERN UPPER MI FRI IN THE DEFORMATION ZONE...WITH THE NAM AND
ECMWF SHOWING WEAK MID-LEVEL Q-VECTOR CONVERGENCE THROUGH THE DAY.
HOWEVER...WITH LACK OF SIGNIFICANT LOW LEVEL LIFT AND FAIRLY STRONG
CONFLUENCE ALOFT...WILL LIMIT ANY POPS TO JUST SLIGHT CHANCE ON
FRIDAY ACROSS THE FAR SOUTH.
ON FRIDAY NIGHT INTO SATURDAY...ANOTHER WEAK UPPER TROUGH ROTATES
THROUGH THE AREA. WITH REMAINING MOISTURE ACROSS THE FAR SOUTH FRI
NIGHT...WILL MAINTAIN LOW CHANCE POPS MAINLY IN MENOMINEE COUNTY BUT
AGAIN THE LIFT IS MINIMAL AT BEST. THE NAM SEEMS TO BE AN OUTLIER IN
DEVELOPING A WEAK AREA OF LOW PRESSURE ALONG THE FRONT OVER LAKE
SUPERIOR AND KEEPING IT NEARLY STATIONARY THROUGH SATURDAY BEFORE
MERGING WITH THE DEVELOPING LOW OVER THE SOUTHERN PLAINS SATURDAY
NIGHT. IN FACT...THE NAM ACTUALLY SHOWS ON LAKE MICHIGAN LAKE EFFECT
DEVELOPING IN SCHOOLCRAFT AND DELTA COUNTIES SATURDAY DUE TO THE
SOUTHERLY FLOW AHEAD OF THE LOW. MEANWHILE...THE ECMWF AND THE GFS
SUGGEST A WEAK OPEN WAVE AT BEST WITH MUCH LESS MOISTURE AND LITTLE
IF ANY QPF ON SATURDAY. GIVEN THE WEAK DYNAMICS AT BEST AND THAT THE
NAM IS THE OUTLIER...WILL GENERALLY FOLLOW THE ECMWF SOLUTION AND
KEEP LIMIT ANY POPS TO SLIGHT CHANCE FOR SATURDAY.
FOR THE SOUTHERN STREAM SYSTEM SAT NIGHT INTO SUNDAY NIGHT MOVING
THROUGH THE SOUTHERN GREAT LAKES...THE 18/12Z RUNS STARTED TO TREND
NORTH AND WEST WITH THE LOW. THE 19/00Z RUNS HAVE GENERALLY
CONTINUED THIS TREND WITH THE 19/00Z ECMWF SHIFTING EVEN FURTHER
NORTH AND WEST. WITH THE SYSTEM CLOSING OFF OVER THE SOUTHWESTERN
STATES...WOULD EXPECT THAT THE SYSTEM OVERALL WILL EJECT OUT INTO
THE PLAINS A LITTLE SLOWER THAN THE MODELS SUGGEST. THIS WOULD ALLOW
THE NORTHERN STREAM ENERGY TO POTENTIALLY PHASE WITH THE SOUTHERN
STREAM ENERGY FURTHER NORTH AND WEST...CAUSING THE LOW TO ALSO TRACK
A LITTLE FURTHER NORTH/WEST. AS SUCH...HAVE OPTED TO BRING LIKELY
POPS ACROSS THE ENTIRE EAST HALF OF UPPER MICHIGAN ON SUNDAY/SUNDAY
NIGHT AND RAISE POPS TO NEAR CATEGORICAL IN NORTH CENTRAL UPPER MI.
THIS TYPE OF TRACK WOULD ALLOW FOR A SETUP FOR DECENT LAKE
ENHANCEMENT IN THOSE AREAS FAVORED BY NORTHERLY WINDS WITH PLENTY
OFF DEEP MOISTURE AND AT LEAST SOME SYNOPTIC LIFT IN THE DEFORMATION
ZONE. DO NOT WANT TO TOTALLY BUY OFF ON THE LATEST ECMWF YET AS IT
IS STILL BY FAR THE FURTHEST N AND W...BUT THERE CERTAINLY EXISTS A
POSSIBILITY OF PLOWABLE SNOWFALL FOR MUCH OF THE EASTERN HALF /OR
PERHAPS THE ENTIRE CWFA/ SUNDAY...AND PERHAPS A SIGNIFICANT SNOW FOR
THE FAVORABLE LAKE ENHANCED AREAS. BOTTOM LINE THOUGH...THERE IS
STILL A GREAT AMOUNT OF UNCERTAINTY SO STAY TUNED...
OTHERWISE...BEHIND THIS SYSTEM THE WEATHER QUIETS DOWN WITH A BROAD
LONG WAVE TROUGH SETTLING ACROSS NORTH AMERICA. EXPECT SOME LAKE
EFFECT MONDAY AS THE MAIN SHORT WAVE TROUGH PASSES THROUGH WITH
LINGERING MOISTURE AND 850MB TEMPS AROUND -20C. HOWEVER...THE SFC
RIDGE QUICKLY BUILDS IN BY TUE MORNING WHICH SHOULD END ANY LES.
COULD BE QUITE A COLD MORNING ON CHRISTMAS EVE MORNING WITH THE
RIDGE OVERHEAD AND CLEARING SKIES. WILL GO WITH TEMPS WELL BELOW
ZERO FOR MOST INTERIOR LOCATIONS. MAY BE ONE OF THOSE -20F MORNINGS
IN THE NORMALLY COLDER SPOTS IF IT STAYS CLEAR AND CALM. SOME LIGHT
SNOW IS POSSIBLE LATER ON CHRISTMAS EVE INTO CHRISTMAS DAY AS THE
FRONTAL SYSTEM MOVES INTO THE AREA ASSOCIATED WITH A FAIRLY POTENT
LOOKING SHORT WAVE TROUGH...BUT DETAILS ARE TOUGH TO PIN DOWN. TEMPS
IN THE EXTENDED STILL LOOK BELOW NORMAL.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z FRIDAY AFTERNOON)
ISSUED AT 1238 PM EST THU DEC 19 2013
HAVE LIMITED IMPROVEMENT THIS AFTERNOON AND EVENING AS LAKE EFFECT
SNOW IS STRONGER AND MORE PERSISTENT THAN PREVIOUSLY EXPECTED. DO
HAVE CONDITIONS SLOWLY IMPROVING INTO THIS EVENING AS HIGH PRESSURE
WILL BE LESS FAVORABLE FOR LAKE EFFECT SNOW.
A DISTURBANCE SLIDING ACROSS UPPER MICHIGAN TONIGHT WILL LEAD TO A
3-5HR BURST OF SNOW AT ALL TAF SITES. THINK KIWD/KSAW WILL SEE THE
WORST CONDITIONS. EXPECT IMPROVEMENT IN THE OVERNIGHT HOURS FROM
WEST TO EAST...ALTHOUGH ALL SITES WILL STILL SEE LIGHT SNOW SHOWERS
AND MVFR CONDITIONS. SNOW SHOWERS WILL CONTINUE INTO EARLY FRIDAY
AFTERNOON AS COLDER AIR AND LINGERING LOW LEVEL MOISTURE LEADS TO
LAKE EFFECT AT ALL SITES.
&&
.MARINE...(FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 452 AM EST THU DEC 19 2013
A LOW DEPARTING EASTERN LAKE SUPERIOR THIS MORNING HAS LED TO AN
INCREASE IN NORTHWEST TO NORTHERLY WINDS ACROSS WESTERN LAKE
SUPERIOR EARLY THIS MORNING AND IT SHOULD SPREAD EAST ACROSS THE
REST OF THE LAKE THROUGH THE MORNING HOURS. ALTHOUGH THERE MAY BE A
FEW GUSTS TO THE 30KT RANGE THIS MORNING...WOULD EXPECT THEM TO
MAINLY BE AROUND 25KTS. A HIGH PRESSURE RIDGE BUILDING OVER
SOUTHERN ONTARIO THIS AFTERNOON WILL WEAKEN THE WINDS THROUGH THE
AFTERNOON AND NIGHT (TO BELOW 20KTS) AS A WEAK LOW TRACKS THROUGH
SOUTHERN LOWER MICHIGAN. THIS HIGH PRESSURE RIDGE WILL CROSS THE
UPPER GREAT LAKES ON FRIDAY AND FRIDAY NIGHT AND LEAD TO CONTINUED
WINDS BELOW 20KTS THROUGH THE FIRST HALF OF THE WEEKEND. A STRONGER
LOW EXITING THE SOUTHERN PLAINS ON SATURDAY AFTERNOON WILL MOVE
THROUGH SOUTHEAST LOWER MICHIGAN ON SUNDAY AND WILL INCREASE
NORTHERLY WINDS ACROSS THE LAKE. AT THIS TIME...EXPECT WINDS TO BE
AROUND 30KTS WITH A FEW GALE FORCE GUSTS TO 35KTS BEFORE DIMINISHING
SUNDAY NIGHT INTO MONDAY.
FINALLY...FREEZING SPRAY WILL BE POSSIBLE DURING THE TIMES OF
STRONGER WINDS...LARGELY TODAY AND LATE SATURDAY NIGHT INTO SUNDAY
NIGHT.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
NONE.
LAKE MICHIGAN...
NONE.
&&
$$
SHORT TERM...SRF
LONG TERM...MRD
AVIATION...TITUS
MARINE...SRF
AREA FORECAST DISCUSSION...UPDATED
NWS ABERDEEN SD
1141 AM CST THU DEC 19 2013
.UPDATE...
18Z AVIATION DISCUSSION UPDATED BELOW.
WITH LAST NIGHTS 6Z AND THE NEW 12Z MODELS ZEROING IN ON MY CWA
FOR THE BAND OF SNOW...HAVE DECIDED TO EXPAND THE ADVISORY EAST TO
ENCOMPASS THE ENTIRE CWA. SNOWFALL AMOUNTS OF 2 TO 5 INCHES CAN BE
EXPECTED WITH HIGH SNOW TO LIQUID RATIOS. LUCKILY WINDS WONT BE
TOO BAD BUT STILL BREEZY WHICH COULD LEAD TO SOME BLOWING AND
DRIFTING. WIND CHILLS WILL ALSO BE BOUNCING UP AGAINST CRITERIA BUT
FOR NOW WILL LET THIS BAND OF SNOW GET THROUGH BEFORE WORRYING TOO
MUCH ABOUT WIND CHILLS. UPDATES ALREADY ISSUED.
&&
.PREVIOUS DISCUSSION...
.SHORT TERM...TODAY THROUGH SATURDAY
MAIN FORECAST CHALLENGE TODAY IS SNOW ACCUMULATIONS ACROSS THE
REGION.
CURRENTLY RADAR SHOWS A VERY THIN BAND OF JET STREAK ENHANCED
SNOW ALONG THE WESTERN AND CENTRAL ND/SD STATE LINE. ONLY
HETTINGER IS REPORTING SNOW WITH SIGNIFICANT VSBY REDUCTIONS BUT
WITH FEW OTHER OBS SITES IN THE BAND WILL GIVE A BEST GUESS THAT
THERE HAS TO BE AT LEAST SOME LIGHT SNOW STRETCHING EAST TOWARD
EUREKA. MODEL GUIDANCE OVERALL SHOWS A SIMILAR PICTURE...AT LEAST
ON THE BROAD SCALE. HOWEVER RECENT HI-RES MODEL RUNS DIFFER
GREATLY IN THE DETAILS. THE HRRR IS VERY SLOW TO PROGRESS ANY
PRECIP ACROSS THE SOUTHERN COUNTIES...KEEPING EVEN PIERRE DRY
UNTIL 18Z. STUCK PRETTY CLOSE TO THE LOCAL 4KM FOR HOURLY POPS.
BUT EVEN THIS SOLUTION IS TRICKY BECAUSE IT BRINGS SIGNIFICANTLY
DRIER AIR INTO THE NORTHEASTERN CWA...KEEPING AREAS ALONG HWY 12
AND NORTH PRECIP FREE EAST OF BROWN COUNTY. WHEREAS 00Z RUNS OF
THE ECMWF/GFS/NAM ARE HITTING THE NORTHERN CWA HARDER THAN IN
PREVIOUS RUNS.
SO PLACEMENT OF THE MAIN FIELD OF QPF HAS LOW FORECASTER
CONFIDENCE TODAY. TO COMPOUND THE CHALLENGE SOME MODELS HAVE THE
SFC HIGH DROPPING IN A LITTLE MORE QUICKLY AND IN DIFFERENT AREAS
OF THE CWA WHICH WILL AFFECT WIND SPEEDS AND SNOW RATIOS. STUCK
WITH A 15:1 RATIO AND SOME AREAS OF BLOWING SNOW...BUT IF THE
WINDS REALLY DIE DOWN THAT COULD MEAN RATIOS CLOSER TO 20:1 AND
LESS OF A BLOWING SNOW CONCERN. CURRENTLY HAVE STORM TOTAL SNOW
AMOUNTS OF 2 TO 4 INCHES WITH HIGHEST AMOUNTS NEAR THAT JET STREAK
ON THE ND/SD BORDER AND WEST OF THE MISSOURI RIVER.
AS THE ARCTIC FRONT MOVES FROM NORTH TO SOUTH TODAY TEMPS WILL
REMAIN STEADY OR FALL THROUGH THE DAY. THEN THE COLD AIR SETTLES
IN THROUGH THE REMAINDER OF THE PERIOD.
.LONG TERM...SATURDAY NIGHT THROUGH WEDNESDAY
THE MODELS AND GFS ENSEMBLES AGREE WELL THROUGH THE LONG TERM WITH
KEEPING THE REGION ON THE COLDER SIDE OF NORMAL. THE UPPER LEVEL
FLOW OVER THE REGION REMAINS FROM THE NORTHWEST THROUGH THE LONG
TERM WITH SHORT WAVE TROUGHS/CLIPPER SYSTEMS DROPPING ACROSS THE
REGION. ONE OR MORE OF THESE SYSTEMS MAY END UP BEING MORE
SIGNIFICANT AS FAR AS BRINGING SOME ACCUMULATING SNOWFALL AND
STRONG WINDS BUT TOO DIFFICULT TO SINGLE OUT AT THIS TIME. HAVE
THE LONG TERM BASICALLY DRY FOR NOW UNTIL THERE IS BETTER MODEL
AGREEMENT WITH THESE CLIPPER SYSTEMS. AT THIS TIME...THE EC WAS
SHOWING A COUPLE CLIPPERS MOVING ACROSS FOR EARLY THROUGH MID WEEK
THAT MAY BRING SOME LIGHT SNOW AND STRONG WINDS. HAVE IN SLIGHT
CHANCES OF LIGHT SNOW ACROSS THE NORTHEAST CWA FOR THE FIRST
CLIPPER SYSTEM ON MONDAY NIGHT. OTHERWISE...MUCH BELOW NORMAL
TEMPERATURES WILL CONTINUE WITH MAYBE SOME MODERATION CLOSER TO
NORMAL BY TUESDAY AND WEDNESDAY. THE ADDITIONAL SNOWFALL TODAY AND
THIS EVENING WILL HAVE A BIG INFLUENCE ON THE TEMPERATURES IN THE
LONG TERM AS ARCTIC AIR MASSES MOVE ACROSS THE REGION. SATURDAY
NIGHT AND SUNDAY NIGHT ARE EXPECTED TO BE IN THE SINGLE DIGITS AND
TEENS BELOW ZERO. HIGHS ON SUNDAY AND MONDAY WILL BE MAINLY IN THE
SINGLE DIGITS EITHER SIDE OF ZERO. TUESDAY AND WEDNESDAY AT THIS
TIME ARE EXPECTED TO BE BACK IN THE UPPER TEENS AND 20S. THIS MAY
END UP CHANGING AS THE MODELS EVOLVE.
&&
.AVIATION...
18Z TAFS FOR THE KABR...KATY...KPIR AND KMBG TERMINALS
A STORM SYSTEM MOVING ACROSS THE REGION WILL BRING LIGHT SNOW AND
NORTHERLY WINDS OF 10 TO 20 KNOTS. THE COMBINATION OF FALLING SNOW
AND THE WINDS WILL CAUSE REDUCTION IN VISIBILITIES TO 3/4SM OR
LESS AT TIMES. CEILINGS WILL ALSO LOWER TO IFR/MVFR RANGE AS WELL.
EXPECT THE LIGHT SNOW TO DIMINISH INTO THE EVENING HOURS AND END
OVERNIGHT WITH CEILINGS INCREASING TO LOW END VFR. WINDS WILL ALSO
DECREASE THROUGH THE NIGHT.
&&
.ABR WATCHES/WARNINGS/ADVISORIES...
SD...WINTER WEATHER ADVISORY UNTIL 9 PM CST /8 PM MST/ THIS EVENING
FOR BUFFALO-CAMPBELL-CORSON-DEWEY-EDMUNDS-FAULK-HAND-HUGHES-
HYDE-JONES-LYMAN-MCPHERSON-POTTER-STANLEY-SULLY-WALWORTH.
WINTER WEATHER ADVISORY UNTIL 6 AM CST FRIDAY FOR BROWN-CLARK-
CODINGTON-DAY-DEUEL-GRANT-HAMLIN-MARSHALL-ROBERTS-SPINK.
MN...WINTER WEATHER ADVISORY UNTIL 6 AM CST FRIDAY FOR BIG STONE-
TRAVERSE.
&&
$$
UPDATE...TDK
SHORT TERM...WISE
LONG TERM...MOHR
AVIATION...SD
WEATHER.GOV/ABERDEEN
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
307 PM CST THU DEC 19 2013
.SHORT TERM...(THIS EVENING THROUGH FRIDAY)
ISSUED AT 307 PM CST THU DEC 19 2013
AS OF MID AFTERNOON THURSDAY...AREA OF LOW PRESSURE SITUATED IN
NORTHEAST KANSAS WITH WARM FRONT EXTENDING NORTHEAST INTO SOUTHERN
IOWA AND NORTHERN ILLINOIS. INCREASING ISENTROPIC LIFT LATER THIS
EVENING AND MOISTURE TRANSPORT OVERRUNNING THE WARM FRONT WILL
SATURATE THE LOW LEVELS...ESPECIALLY AFTER 00Z. FORECAST SOUNDINGS
STILL SHOW A COMPLICATED TOP DOWN PRECIPITATION TYPE SCENARIO WITH
BOTH A WARM NOSE AND A LOSS OF ICE IN THE UPPER LEVELS. FIRST...THE
PROBABILITY OF NO ICE PRESENT SHIFTED SLIGHTLY NORTH FROM
PREVIOUS FORECAST. 19.12Z NAM AND RAP NOW SHOW THIS EXTENDING NORTH
TO JUST SHY OF THE I-90 CORRIDOR IN WISCONSIN. IT IS NOT UNTIL VERY
EARLY FRIDAY MORNING THAT ICE GETS REINTRODUCED...AND A CHANGEOVER
TO LIGHT SNOW WOULD THEN OCCUR FOR PLACES SUCH AS VIROQUA OVER TO
JUNEAU/ADAMS COUNTIES. AT THE SAME TIME...RAP SOUNDINGS FOR DBQ
SHOW MAX WARM NOSE OF +4 DEGREES...AROUND +1 FOR BLR...AND THEN
BELOW ZERO FOR AREAS TO THE NORTH. SO...TIGHT GRADIENT FOR
FREEZING RAIN AND SNOW LINE. AS FAR AS ICE ACCUMULATIONS...UP TO
1/10 OF AN INCH STILL EXPECTED ON EXPOSED SURFACES...WHICH WILL
MAKE FOR SLICK TRAVEL OVERNIGHT INTO THE MORNING HOURS FRIDAY.
GIVEN THIS NORTHWARD JOG IN THE LOSS OF ICE / WARM NOSE...HAVE
EXPANDED THE FREEZING RAIN ADVISORY TO INCLUDE VERNON...JUNEAU AND
ADAMS COUNTIES IN WISCONSIN.
THE NORTHERN SIDE OF THIS WEATHER SYSTEM STILL EXPECTED TO PRODUCE A
BAND OF ACCUMULATING SNOW ALONG AND NORTH OF I-90...MAINLY AFTER
MIDNIGHT INTO FRIDAY MORNING. NO BIG CHANGES FROM
PREVIOUS FORECAST...WITH 1 TO 2 INCHES FOR MOST LOCATIONS AND
LOCALLY 3 INCH AMOUNTS POSSIBLE MAINLY FOR CENTRAL WISCONSIN. THIS
TOO COULD MAKE FOR SLICK ROADWAYS FOR THE FRIDAY MORNING
COMMUTE...AND CONSIDERED A HEADLINE FOR THIS BUT WILL HOLD OFF NOW
GIVEN COLLABORATION. IF LATER FORECASTS SHOW AN UPTICK IN
AMOUNTS...OR A DELAY MORE TOWARD THE MORNING COMMUTE...THEN AN
WINTER WEATHER ADVISORY MAY BE NEEDED FOR A FEW COUNTIES.
.LONG TERM...(FRIDAY NIGHT THROUGH THURSDAY)
ISSUED AT 307 PM CST THU DEC 19 2013
FOCUS OF THIS PERIOD IS SQUARELY ON THE WEEKEND AND THE POTENTIAL
FOR A WINTER STORM TO IMPACT PARTS OF THE FORECAST AREA. STILL
SOME DIFFERENCES BETWEEN THE MODELS BUT THE 19.12Z GFS AND ECMWF
ARE IN BETTER AGREEMENT WITH THE OVERALL PATTERN WITH THE 19.12Z
NAM APPEARING AT THIS TIME TO BE THE ODD MODEL OUT. THE UPPER
LEVEL LOW CURRENTLY ALONG THE CALIFORNIA COAST WILL MOVE OUT OF
THE DESERT SOUTHWEST AND TRACK NORTHEAST ACROSS THE CENTRAL
PORTION OF THE COUNTRY OVER THE WEEKEND. AS IT MOVES TOWARD THE
AREA...A NORTHERN STREAM SHORT WAVE WILL START TO MOVE TOWARD THE
UPPER MIDWEST FROM SOUTHWEST CANADA. THE DIFFERENCES IN THE MODEL
SOLUTIONS REVOLVE AROUND WHETHER THESE TWO SYSTEMS GET PHASED OR
WHETHER THEY STAY SEPARATE. THE NAM WOULD SUGGEST THEY GET PHASED
WHICH PUSHES THE SURFACE LOW AND ASSOCIATED QPF FARTHER SOUTHEAST.
THE GFS AND ECMWF DO NOT PHASE THE TWO SYSTEMS WHICH BRINGS THE
SURFACE LOW AND QPF BACK MORE TO THE NORTHWEST.
THE FORCING FROM THE SHORT WAVE TROUGH WILL START TO MOVE IN
SATURDAY NIGHT. MODERATE TO STRONG PV ADVECTION IN THE 500-300 MB
LAYER SHOULD OCCUR LATE SATURDAY NIGHT JUST AHEAD OF THE WAVES
PASSAGE. MODERATE TO STRONG QG CONVERGENCE WILL BE PRODUCED BY THE
WAVE AND CENTERED OVER THE SOUTHEAST PART OF THE FORECAST AREA AT
12Z SUNDAY. WEAK TO MODERATE FRONTOGENESIS IS SHOWN BY THE GFS IN
THE 600-500 MB LAYER BETWEEN 06Z AND 18Z SUNDAY...ALSO OVER THE
SOUTHEAST PORTIONS OF THE FORECAST AREA. THERE MAY ALSO BE SOME
JET DYNAMICS THAT COME INTO PLAY AS WELL. THE GFS IS SUGGESTING A
SPLIT JET WITH THE AREA UNDER THE RIGHT ENTRANCE REGION OF THE
NORTHERN STREAM JET CORE TO ADD SOME AGEOSTROPHIC LIFT TO THE MIX.
THE GFS BUFKIT SOUNDING FOR BLUE RIVER SUGGEST THE DENDRITIC
GROWTH ZONE SHOULD BE ABOUT 100 MB DEEP WITH GOOD VERTICAL MOTIONS
THROUGH IT. THIS SHOULD LEAD TO SNOW RATIOS IN THE 14-16 TO 1
RANGE LEADING TO SNOW ACCUMULATIONS OF 4 TO 7 INCHES FROM ABOUT
FAYETTE COUNTY IOWA NORTHEAST INTO ADAMS/JUNEAU COUNTIES IN
CENTRAL WISCONSIN. THE POTENTIAL FOR THE HIGHER AMOUNTS IS THE
GREATEST IN PRIMARILY GRANT COUNTY WISCONSIN. THE NORTHWEST WINDS
WILL COME UP SUNDAY ON THE BACK SIDE OF THE SYSTEM WHICH WILL
LIKELY LEAD TO SOME DRIFTING SNOW AND POSSIBLY A LITTLE BLOWING
SNOW OVER THE MORE OPEN AREAS OF NORTHEAST IOWA. IN COORDINATION
WITH SURROUNDING OFFICES...WILL ISSUE A WINTER STORM WATCH FOR
SATURDAY NIGHT AND SUNDAY FOR THE ACCUMULATING SNOW AND ANY
POSSIBLE IMPACT ON THE BACK SIDE OF THE SYSTEM.
WITH THE FOCUS ON THE WEEKEND SYSTEM...HAVE NOT LOOKED EXTENSIVELY
AT THE FORECAST FOR NEXT WEEK. HAVE LET THE MODEL CONSENSUS GRIDS
RIDE WHICH GIVES A SMALL CHANCE FOR SOME SNOW TUESDAY AND TUESDAY
NIGHT ACROSS THE NORTH AS ANOTHER NORTHERN STREAM SHORT WAVE
TROUGH MOVES ACROSS THE UPPER MIDWEST AND GREAT LAKES REGION. THE
COLDEST TEMPERATURES IN THE FORECAST LOOK TO BE BEHIND THE WEEKEND
SYSTEM WITH LOWS IN THE SINGLE DIGITS ABOVE AND BELOW ZERO SUNDAY
NIGHT...HIGHS ONLY IN THE SINGLE DIGITS ABOVE ZERO MONDAY WITH
SINGLE DIGITS BELOW ZERO FOR THE ENTIRE AREA MONDAY NIGHT.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z FRIDAY AFTERNOON)
ISSUED AT 1124 AM CST THU DEC 19 2013
INCREASING MOISTURE DURING THE AFTERNOON WILL LEAD TO A GRADUAL
LOWERING OF THE CEILINGS AT KRST/KLSE...DETERIORATING MID EVENING
AS LOW LEVEL MOISTURE REALLY RAMPS UP. TRENDS IN THE FORECAST
SUGGEST A LITTLE LATER START TO PRECIPITATION...SO HAVE ADJUSTED
ONSET TIME A FEW HOURS. OTHERWISE...STILL EXPECTING SNOW TO THE
PREDOMINANT PRECIPITATION TYPE THOUGH THE FREEZING DRIZZLE/RAIN
WILL BE JUST A FEW COUNTIES TO THE SOUTH...ESPECIALLY FOR KLSE.
THE BULK OF THE PRECIPITATION LOOKS TO BE IN THE 06-12Z
TIMEFRAME...THEN TAPERING OFF FRIDAY MORNING. TOTAL AMOUNTS SHOULD
BE IN THE 1 TO MAYBE 2 INCH RANGE. LOW LEVEL MOISTURE HANGS
AROUND MUCH OF FRIDAY...SO HAVE KEPT RESTRICTIVE CEILINGS IN
PLACE THROUGH 18Z. VISIBILITIES ARE EXPECTED TO LOWER TO IFR
AFTER MIDNIGHT DURING THE PEAK OF THE LIGHT SNOW...IMPROVING TO
VFR BY 12Z.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
WI...FREEZING RAIN ADVISORY UNTIL 6 AM CST FRIDAY FOR WIZ043-044-
053>055-061.
WINTER STORM WATCH FROM SATURDAY EVENING THROUGH SUNDAY
AFTERNOON FOR WIZ043-044-053>055-061.
MN...NONE.
IA...FREEZING RAIN ADVISORY UNTIL 6 AM CST FRIDAY FOR IAZ010-011-019-
029-030.
WINTER STORM WATCH FROM SATURDAY EVENING THROUGH SUNDAY
AFTERNOON FOR IAZ011-029-030.
&&
$$
SHORT TERM...ZT
LONG TERM...04
AVIATION...ZT