Forecast Discussions mentioning any of
"HRRR" "RR" "RUC13" "RUC" received at GSD on 12/19/11
AREA FORECAST DISCUSSION
NWS NEW YORK NY
937 PM EST SUN DEC 18 2011
.SYNOPSIS...
A HIGH PRESSURE RIDGE WILL DRIFT OVER THE REGION TONIGHT...AND
OFFSHORE ON MONDAY. A COLD FRONT WILL PASS MONDAY NIGHT. HIGH
PRESSURE BUILDS OVER THE AREA TUESDAY. A WARM FRONT APPROACHES
FROM THE SOUTH TUESDAY NIGHT...THEN LIFTS TO THE NORTH
WEDNESDAY...FOLLOWED BY A COLD FRONT WEDNESDAY NIGHT...AS AN AREA
OF LOW PRESSURE PASSES TO OUR NORTH. HIGH PRESSURE THEN BUILDS IN
TO OUR NORTH THURSDAY THROUGH SUNDAY...AS A COUPLE OF LOW PRESSURE
SYSTEMS PASS TO OUR SOUTH FRIDAY AND THEN LATE NEXT WEEKEND.
&&
.NEAR TERM /UNTIL 6 AM MONDAY MORNING/...
HIGH PRESSURE CURRENTLY OVER THE VIRGINIA COAST WILL CONTINUE TO
TRANSLATE SOUTH AND EAST OVERNIGHT. WINDS ARE CALM IN MOST
LOCATIONS WITH TEMPERATURES ALREADY IN THE TEENS TO AROUND 30 IN
THE NYC METRO AREA. DRY AIR STILL IN PLACE OVER THE AREA WITH THE
LATEST SOUNDING SHOWING PW OF 0.09 IN. HIGH AND MID LEVEL CLOUDS
OVER UPSTATE NY ARE MOVING TOWARDS THE AREA BUT DUE TO THE DRY AIR
IN PLACE...ONLY HIGH CLOUDS EXPECTED OVERNIGHT AND ARE ALREADY
MOVING IN AS OF 02Z OBS.
HAVE UPDATED TEMPERATURES AND DEW POINTS TO REFLECT THE CURRENT
CONDITIONS. WITH A SW FLOW BUILDING IN BEHIND THE HIGH PRESSURE
EARLY MONDAY MORNING...TEMPERATURES IN THE NYC METRO AREA AND ON
LONG ISLAND COULD EXPERIENCE A QUICKER WARMING THAN OTHER AREAS.
&&
.SHORT TERM /6 AM MONDAY MORNING THROUGH TUESDAY NIGHT/...
LOW PRES OVER ONTARIO WILL RACE EWD ON MON UNDER THE INFLUENCE OF
A STRENGTHENING 120KT H3 JET. AS THE ASSOCIATED COLD FRONT
APPROACHES...THE PRES GRAD WILL TIGHTEN...ALLOWING FOR INCREASING
WSW WINDS DURING THE DAY. SUSTAINED WINDS WILL MAX OUT IN THE
15-20KT RANGE WITH SOME GUSTS TO AROUND 30KT. STRONGEST WINDS WILL
BE ALONG THE S SHORES. 12Z OKX SOUNDING INDICATED 0.14 INCHES OF
PW...SO THE FCST WILL BE KEPT DRY DURING THE DAYTIME HOURS WITH
MOISTURE TRANSPORT VECTORS NOT REACHING THE CWA TIL AROUND 00Z
TUE. TEMPS WARMER THAN SUN DUE TO BETTER MIXING ALL AREAS AND AN
ONSHORE COMPONENT ON THE COASTS.
THE COLD FRONT PASSES MON NGT. 12Z MODELS IN GOOD AGREEMENT WITH
THIS. MOISTURE REMAINS EXTREMELY LIMITED...BUT ENOUGH LAKE MOISTURE
MAY ALLOW FOR A FEW SPRINKLES AND/OR FLURRIES. HAVE RETAINED THIS
WEATHER IN THE GRIDS. BL TOO WARM FOR FLAKES NEAR THE COASTS
INITIALLY...BUT AT THE CWA GETS INTO THE RR QUAD OF THE H3 170 PLUS
KT H3 JET AFT MIDNIGHT...A FEW FLURRIES POSSIBLE POST FRONTAL ACROSS
ALL AREAS. MOS WAS IN GOOD AGREEMENT FOR TEMPS...SO A BLEND WAS
USED.
&&
.LONG TERM /WEDNESDAY THROUGH SUNDAY/...
THE GFS IS MORE PROGRESSIVE THAN THE NAM/ECMWF/SREF WITH THE SYSTEM
IMPACTING THE REGION MID WEEK...AS IS ITS BIAS...SO USED A BLEND OF
THE SLOWER SOLUTIONS TUESDAY THROUGH WEDNESDAY. WEDNESDAY NIGHT
THROUGH CHRISTMAS DAY...THERE ARE QUITE A BIT OF DIFFERENCES BETWEEN
THE GFS AND ECMWF IN HOW THEY HANDLE THE NEXT SYSTEM EJECTING FROM
THE SW U.S. AND ITS INTERACTION WITH THE NORTHERN STREAM. DUE TO
BETTER RUN TO RUN CONSISTENCY AND BETTER OVERALL VERIFICATION IN THE
LONG TERM...LEANED HEAVILY TOWARDS THE ECMWF WEDNESDAY NIGHT THROUGH
SUNDAY.
RIDGING BUILDS INTO THE AREA TUESDAY/TUESDAY NIGHT...THEN SLIDES
OFFSHORE WEDNESDAY AS A SOUTHERN STREAM TROUGH LIFTS INTO THE UPPER
OHIO RIVER VALLEY...THIS TROUGH WILL SUPPORT A SURFACE LOW TRACKING
TO OUR NORTH WEDNESDAY.
TUESDAY SHOULD BE DRY UNDERNEATH THE RIDGE BUILDING IN. OVER RUNNING
SETS UP TUESDAY NIGHT...AHEAD OF A SURFACE AND 850 HPA WARM
FRONT...EXPECT LIGHT PRECIPITATION TO GRADUALLY DEVELOP FROM SW TO
NE FROM TUESDAY NIGHT INTO WEDNESDAY MORNING. LOW LEVEL THERMAL
PROFILES SUPPORT RAIN ACROSS NYC METRO/LONG ISLAND WITH A WINTRY
MIX...INCLUDING POSSIBLY SOME FREEZING RAIN ACROSS THE
INTERIOR...BEFORE CHANGING TO ALL RAIN AS THE WARM FRONT LIFTS TO
THE NORTH WEDNESDAY MORNING. 40-50 KT LOW LEVEL JET MOVES IN BY
WEDNESDAY AFTERNOON SUPPORTING MORE WIDESPREAD RAIN.
THE AFOREMENTIONED TROUGH LIFT JUST OVER THE REGION WEDNESDAY
NIGHT...ALLOWING PRECIPITATION TO TAPER OFF FROM W TO E BY THURSDAY
MORNING - STILL CARRY SLIGHT CHANCE POPS THURSDAY MORNING AS THERE
HAS BEEN SOME UNCERTAINTY IN TIMING OF THE SYSTEM...WITH SOME
SUGGESTIONS IT COULD END UP A TAD SLOWER THAN CURRENTLY FORECAST.
RIDGING BUILDS IN THURSDAY WITH ITS AXIS SLIDING OFFSHORE THURSDAY
NIGHT. FOLLOWING THE ECMWF...IT APPEARS THAT THE SHEARING TROUGH
FORECAST TO LIFT OUT OF BAJA CA WEDNESDAY...APPROACHES BY LATE
THURSDAY NIGHT...THEN CROSSES ON FRIDAY...WITH AN ASSOCIATED
COASTAL LOW PASSING TO THE SOUTH ALONG A STALLED FRONTAL BOUNDARY.
LOW LEVEL THERMAL PROFILES SUGGEST SNOW OR RAIN/SNOW ACROSS NORTHERN
ZONES AND RAIN ACROSS SOUTHERN ZONES BY LATE THURSDAY NIGHT...WITH
PRECIPITATION TRANSITIONING TO ALL RAIN DURING THE DAY ON FRIDAY ON
THE NORTHERN TIER. THERE IS QUITE A BIT OF UNCERTAINTY WITH THIS
SYSTEM...WITH SOME POTENTIAL IT COULD END UP MISSING US ENTIRELY TO
THE SOUTH.
FRIDAY NIGHT AND SATURDAY WILL FEATURE SW FLOW ALOFT...WITH SOME
EMBEDDED SHORTWAVES. THESE WARRANT SLIGHT CHANCE POPS FOR NOW...BUT
MORE THAN LIKELY WILL BE DRY.
THE NEXT POTENTIAL SYSTEM IMPACTS THE REGION LATE CHRISTMAS
EVE/CHRISTMAS DAY...THIS TIME EJECTING FROM NEAR THE FOUR CORNERS
REGION AROUND THURSDAY. LIKE THE SYSTEM FOR FRIDAY...THE SURFACE LOW
WILL TRACK TO THE SOUTH...THE QUESTION IS HOW FAR. FOLLOWING THE
ECMWF...HAVE SLIGHT CHANCE POPS FOR LIGHT SNOW DEVELOPING ACROSS
MOST ZONES LATE SATURDAY NIGHT...AND CONTINUING INTO SUNDAY
MORNING...THEN CHANGING TO RAIN IN THE AFTERNOON. ONCE AGAIN - LOW
CONFIDENCE AT THIS TIME.
NEAR NORMAL TEMPERATURES ARE EXPECTED TUESDAY...THEN ABOVE NORMAL
TEMPERATURES TUESDAY NIGHT THROUGH THURSDAY NIGHT. NEAR NORMAL
TEMPERATURES ARE FORECAST FRIDAY-SUNDAY.
&&
.AVIATION /03Z MONDAY THROUGH FRIDAY/...
HIGH PRESSURE OVER THE AREA DRIFTS SOUTH MONDAY AS A COLD FRONT
APPROACHES.
VFR. LIGHT AND VARIABLE WINDS BECOME WEST TO SOUTHWEST OVERNIGHT.
GUSTS DEVELOP AFTER 15Z MONDAY AND PEAK IN THE MID AFTERNOON 20 TO
25 KT.
OUTLOOK FOR 00Z TUESDAY THROUGH FRIDAY...
MONDAY NIGHT...VFR. WINDS SHIFT FROM THE SOUTHWEST TO NORTHWEST LATE
BEHIND A COLD FRONT. GUSTY WINDS POSSIBLE LATE.
TUESDAY...VFR.
TUESDAY NIGHT AND WEDNESDAY...SUB VFR IN RAIN...A WINTRY MIX
POSSIBLE INLAND LATE TUESDAY NIGHT. BECOMING VFR WEDNESDAY NIGHT.
THURSDAY...VFR.
FRIDAY...SUB-VFR POSSIBLE.
&&
.MARINE...
LIGHT WINDS TNGT AS HIGH PRES BUILDS OVER THE WATERS. THE HIGH
DRIFTS E OF THE CSTL WATERS MON...ALLOWING FOR A TIGHTENING PRES
GRAD TO DEVELOP THRU THE DAY AS A COLD FRONT APPROACHES FROM THE W.
STRENGTHENING WSW WINDS WILL BE THE RESULT. SCA WILL REMAIN IN
EFFECT FOR ALL WATERS EXCEPT FOR THE ERN OCEAN...WHERE THE GALE
WATCH WILL BE RETAINED. WINDS WEAKEN INVOF THE FRONT
OVERNIGHT...THEN VEER TO THE NW BEHIND THE FRONT EARLY TUE MRNG.
SCA LEVEL SEAS COULD LINGER INTO TUESDAY ON THE FAR EASTERN COASTAL
WATERS...OTHERWISE SUB-SCA CONDITIONS ARE EXPECTED TUESDAY AND
TUESDAY NIGHT. SOUTHERLY FLOW AHEAD OF A STORM SYSTEM
WEDNESDAY...SHOULD AT LEAST BUILD SEAS ON THE COASTAL OCEAN WATERS
TO SCA LEVELS...WITH GUSTY WINDS CONTINUING THEM AT SCA LEVELS INTO
THURSDAY. THERE IS SOME POTENTIAL FOR SCA LEVEL GUSTS ON ALL WATERS
WEDNESDAY-THURSDAY...BUT NOT QUITE CONFIDENT ENOUGH TO GO WITH THIS
IN THE FORECAST AT THIS TIME.
FOR NOW GOING WITH SUB-SCA CONDITIONS ON FRIDAY WITH A COASTAL LOW
PASSING TO THE SOUTH...BUT THERE IS MUCH UNCERTAINTY IN THIS.
&&
.HYDROLOGY...
TRACE AMOUNTS OF PCPN ARE POSSIBLE MON NGT.
THERE IS THE POTENTIAL FOR AROUND A 1/4 TO 1/2 AN INCH OF LIQUID
EQUIVALENT TO FALL OVER THE REGION FROM TUESDAY NIGHT INTO WEDNESDAY
NIGHT. SOME OF THIS SHOULD FALL AS FROZEN PRECIPITATION ACROSS
MAINLY NORTHERN INTERIOR ZONES INTO WEDNESDAY MORNING. NO
SIGNIFICANT HYDROLOGIC IMPACT IS CURRENTLY EXPECTED.
&&
.OKX WATCHES/WARNINGS/ADVISORIES...
CT...NONE.
NY...NONE.
NJ...NONE.
MARINE...SMALL CRAFT ADVISORY FROM 10 AM MONDAY TO 1 AM EST TUESDAY FOR
ANZ330-335-338-340-345-355.
GALE WATCH FROM MONDAY MORNING THROUGH LATE MONDAY NIGHT FOR
ANZ350-353.
&&
$$
SYNOPSIS...JMC/MALOIT
NEAR TERM...JMC/LN
SHORT TERM...JMC/LN
LONG TERM...MALOIT
AVIATION...MET
MARINE...JMC/MALOIT
HYDROLOGY...JMC/MALOIT
AREA FORECAST DISCUSSION
NWS NEW YORK NY
930 PM EST SUN DEC 18 2011
.SYNOPSIS...
A HIGH PRESSURE RIDGE WILL DRIFT OVER THE REGION TONIGHT...AND
OFFSHORE ON MONDAY. A COLD FRONT WILL PASS MONDAY NIGHT. HIGH
PRESSURE BUILDS OVER THE AREA TUESDAY. A WARM FRONT APPROACHES
FROM THE SOUTH TUESDAY NIGHT...THEN LIFTS TO THE NORTH
WEDNESDAY...FOLLOWED BY A COLD FRONT WEDNESDAY NIGHT...AS AN AREA
OF LOW PRESSURE PASSES TO OUR NORTH. HIGH PRESSURE THEN BUILDS IN
TO OUR NORTH THURSDAY THROUGH SUNDAY...AS A COUPLE OF LOW PRESSURE
SYSTEMS PASS TO OUR SOUTH FRIDAY AND THEN LATE NEXT WEEKEND.
&&
.NEAR TERM /UNTIL 6 AM MONDAY MORNING/...
HIGH PRESSURE CURRENTLY OVER THE VIRGINIA COAST WILL CONTINUE TO
TRANSLATE SOUTH AND EAST OVERNIGHT. WINDS ARE CALM IN MOST
LOCATIONS WITH TEMPERATURES ALREADY IN THE TEENS TO AROUND 30 IN
THE NYC METRO AREA. DRY AIR STILL IN PLACE OVER THE AREA WITH THE
LATEST SOUNDING SHOWING PW OF 0.09 IN. HIGH AND MID LEVEL CLOUDS
OVER UPSTATE NY ARE MOVING TOWARDS THE AREA BUT DUE TO THE DRY AIR
IN PLACE...ONLY HIGH CLOUDS EXPECTED OVERNIGHT AND ARE ALREADY
MOVING IN AS OF 02Z OBS.
HAVE UPDATED TEMPERATURES AND DEW POINTS TO REFLECT THE CURRENT
CONDITIONS. WITH A SW FLOW BUILDING IN BEHIND THE HIGH PRESSURE
EARLY MONDAY MORNING...TEMPERATURES IN THE NYC METRO AREA AND ON
LONG ISLAND COULD EXPERIENCE A QUICKER WARMING THAN OTHER AREAS.
&&
.SHORT TERM /6 AM MONDAY MORNING THROUGH TUESDAY NIGHT/...
LOW PRES OVER ONTARIO WILL RACE EWD ON MON UNDER THE INFLUENCE OF
A STRENGTHENING 120KT H3 JET. AS THE ASSOCIATED COLD FRONT
APPROACHES...THE PRES GRAD WILL TIGHTEN...ALLOWING FOR INCREASING
WSW WINDS DURING THE DAY. SUSTAINED WINDS WILL MAX OUT IN THE
15-20KT RANGE WITH SOME GUSTS TO AROUND 30KT. STRONGEST WINDS WILL
BE ALONG THE S SHORES. 12Z OKX SOUNDING INDICATED 0.14 INCHES OF
PW...SO THE FCST WILL BE KEPT DRY DURING THE DAYTIME HOURS WITH
MOISTURE TRANSPORT VECTORS NOT REACHING THE CWA TIL AROUND 00Z
TUE. TEMPS WARMER THAN SUN DUE TO BETTER MIXING ALL AREAS AND AN
ONSHORE COMPONENT ON THE COASTS.
THE COLD FRONT PASSES MON NGT. 12Z MODELS IN GOOD AGREEMENT WITH
THIS. MOISTURE REMAINS EXTREMELY LIMITED...BUT ENOUGH LAKE MOISTURE
MAY ALLOW FOR A FEW SPRINKLES AND/OR FLURRIES. HAVE RETAINED THIS
WEATHER IN THE GRIDS. BL TOO WARM FOR FLAKES NEAR THE COASTS
INITIALLY...BUT AT THE CWA GETS INTO THE RR QUAD OF THE H3 170 PLUS
KT H3 JET AFT MIDNIGHT...A FEW FLURRIES POSSIBLE POST FRONTAL ACROSS
ALL AREAS. MOS WAS IN GOOD AGREEMENT FOR TEMPS...SO A BLEND WAS
USED.
&&
.LONG TERM /WEDNESDAY THROUGH SUNDAY/...
THE GFS IS MORE PROGRESSIVE THAN THE NAM/ECMWF/SREF WITH THE SYSTEM
IMPACTING THE REGION MID WEEK...AS IS ITS BIAS...SO USED A BLEND OF
THE SLOWER SOLUTIONS TUESDAY THROUGH WEDNESDAY. WEDNESDAY NIGHT
THROUGH CHRISTMAS DAY...THERE ARE QUITE A BIT OF DIFFERENCES BETWEEN
THE GFS AND ECMWF IN HOW THEY HANDLE THE NEXT SYSTEM EJECTING FROM
THE SW U.S. AND ITS INTERACTION WITH THE NORTHERN STREAM. DUE TO
BETTER RUN TO RUN CONSISTENCY AND BETTER OVERALL VERIFICATION IN THE
LONG TERM...LEANED HEAVILY TOWARDS THE ECMWF WEDNESDAY NIGHT THROUGH
SUNDAY.
RIDGING BUILDS INTO THE AREA TUESDAY/TUESDAY NIGHT...THEN SLIDES
OFFSHORE WEDNESDAY AS A SOUTHERN STREAM TROUGH LIFTS INTO THE UPPER
OHIO RIVER VALLEY...THIS TROUGH WILL SUPPORT A SURFACE LOW TRACKING
TO OUR NORTH WEDNESDAY.
TUESDAY SHOULD BE DRY UNDERNEATH THE RIDGE BUILDING IN. OVER RUNNING
SETS UP TUESDAY NIGHT...AHEAD OF A SURFACE AND 850 HPA WARM
FRONT...EXPECT LIGHT PRECIPITATION TO GRADUALLY DEVELOP FROM SW TO
NE FROM TUESDAY NIGHT INTO WEDNESDAY MORNING. LOW LEVEL THERMAL
PROFILES SUPPORT RAIN ACROSS NYC METRO/LONG ISLAND WITH A WINTRY
MIX...INCLUDING POSSIBLY SOME FREEZING RAIN ACROSS THE
INTERIOR...BEFORE CHANGING TO ALL RAIN AS THE WARM FRONT LIFTS TO
THE NORTH WEDNESDAY MORNING. 40-50 KT LOW LEVEL JET MOVES IN BY
WEDNESDAY AFTERNOON SUPPORTING MORE WIDESPREAD RAIN.
THE AFOREMENTIONED TROUGH LIFT JUST OVER THE REGION WEDNESDAY
NIGHT...ALLOWING PRECIPITATION TO TAPER OFF FROM W TO E BY THURSDAY
MORNING - STILL CARRY SLIGHT CHANCE POPS THURSDAY MORNING AS THERE
HAS BEEN SOME UNCERTAINTY IN TIMING OF THE SYSTEM...WITH SOME
SUGGESTIONS IT COULD END UP A TAD SLOWER THAN CURRENTLY FORECAST.
RIDGING BUILDS IN THURSDAY WITH ITS AXIS SLIDING OFFSHORE THURSDAY
NIGHT. FOLLOWING THE ECMWF...IT APPEARS THAT THE SHEARING TROUGH
FORECAST TO LIFT OUT OF BAJA CA WEDNESDAY...APPROACHES BY LATE
THURSDAY NIGHT...THEN CROSSES ON FRIDAY...WITH AN ASSOCIATED
COASTAL LOW PASSING TO THE SOUTH ALONG A STALLED FRONTAL BOUNDARY.
LOW LEVEL THERMAL PROFILES SUGGEST SNOW OR RAIN/SNOW ACROSS NORTHERN
ZONES AND RAIN ACROSS SOUTHERN ZONES BY LATE THURSDAY NIGHT...WITH
PRECIPITATION TRANSITIONING TO ALL RAIN DURING THE DAY ON FRIDAY ON
THE NORTHERN TIER. THERE IS QUITE A BIT OF UNCERTAINTY WITH THIS
SYSTEM...WITH SOME POTENTIAL IT COULD END UP MISSING US ENTIRELY TO
THE SOUTH.
FRIDAY NIGHT AND SATURDAY WILL FEATURE SW FLOW ALOFT...WITH SOME
EMBEDDED SHORTWAVES. THESE WARRANT SLIGHT CHANCE POPS FOR NOW...BUT
MORE THAN LIKELY WILL BE DRY.
THE NEXT POTENTIAL SYSTEM IMPACTS THE REGION LATE CHRISTMAS
EVE/CHRISTMAS DAY...THIS TIME EJECTING FROM NEAR THE FOUR CORNERS
REGION AROUND THURSDAY. LIKE THE SYSTEM FOR FRIDAY...THE SURFACE LOW
WILL TRACK TO THE SOUTH...THE QUESTION IS HOW FAR. FOLLOWING THE
ECMWF...HAVE SLIGHT CHANCE POPS FOR LIGHT SNOW DEVELOPING ACROSS
MOST ZONES LATE SATURDAY NIGHT...AND CONTINUING INTO SUNDAY
MORNING...THEN CHANGING TO RAIN IN THE AFTERNOON. ONCE AGAIN - LOW
CONFIDENCE AT THIS TIME.
NEAR NORMAL TEMPERATURES ARE EXPECTED TUESDAY...THEN ABOVE NORMAL
TEMPERATURES TUESDAY NIGHT THROUGH THURSDAY NIGHT. NEAR NORMAL
TEMPERATURES ARE FORECAST FRIDAY-SUNDAY.
&&
.AVIATION /02Z MONDAY THROUGH FRIDAY/...
HIGH PRESSURE OVER THE AREA DRIFTS SOUTH MONDAY AS A COLD FRONT
APPROACHES.
VFR. NORTHERLY WINDS UNDER 10 KT BECOME WEST TO SOUTHWEST TONIGHT.
GUSTS DEVELOP AFTER 15Z MONDAY AND PEAK IN THE MID AFTERNOON 20 TO
25 KT.
OUTLOOK FOR 00Z TUESDAY THROUGH FRIDAY...
MONDAY NIGHT...VFR. WINDS SHIFT FROM THE SOUTHWEST TO NORTHWEST LATE
BEHIND A COLD FRONT. GUSTY WINDS POSSIBLE LATE.
TUESDAY...VFR.
TUESDAY NIGHT AND WEDNESDAY...SUB VFR IN RAIN...A WINTRY MIX
POSSIBLE INLAND LATE TUESDAY NIGHT. BECOMING VFR WEDNESDAY NIGHT.
THURSDAY...VFR.
FRIDAY...SUB-VFR POSSIBLE.
&&
.MARINE...
LIGHT WINDS TNGT AS HIGH PRES BUILDS OVER THE WATERS. THE HIGH
DRIFTS E OF THE CSTL WATERS MON...ALLOWING FOR A TIGHTENING PRES
GRAD TO DEVELOP THRU THE DAY AS A COLD FRONT APPROACHES FROM THE W.
STRENGTHENING WSW WINDS WILL BE THE RESULT. SCA WILL REMAIN IN
EFFECT FOR ALL WATERS EXCEPT FOR THE ERN OCEAN...WHERE THE GALE
WATCH WILL BE RETAINED. WINDS WEAKEN INVOF THE FRONT
OVERNIGHT...THEN VEER TO THE NW BEHIND THE FRONT EARLY TUE MRNG.
SCA LEVEL SEAS COULD LINGER INTO TUESDAY ON THE FAR EASTERN COASTAL
WATERS...OTHERWISE SUB-SCA CONDITIONS ARE EXPECTED TUESDAY AND
TUESDAY NIGHT. SOUTHERLY FLOW AHEAD OF A STORM SYSTEM
WEDNESDAY...SHOULD AT LEAST BUILD SEAS ON THE COASTAL OCEAN WATERS
TO SCA LEVELS...WITH GUSTY WINDS CONTINUING THEM AT SCA LEVELS INTO
THURSDAY. THERE IS SOME POTENTIAL FOR SCA LEVEL GUSTS ON ALL WATERS
WEDNESDAY-THURSDAY...BUT NOT QUITE CONFIDENT ENOUGH TO GO WITH THIS
IN THE FORECAST AT THIS TIME.
FOR NOW GOING WITH SUB-SCA CONDITIONS ON FRIDAY WITH A COASTAL LOW
PASSING TO THE SOUTH...BUT THERE IS MUCH UNCERTAINTY IN THIS.
&&
.HYDROLOGY...
TRACE AMOUNTS OF PCPN ARE POSSIBLE MON NGT.
THERE IS THE POTENTIAL FOR AROUND A 1/4 TO 1/2 AN INCH OF LIQUID
EQUIVALENT TO FALL OVER THE REGION FROM TUESDAY NIGHT INTO WEDNESDAY
NIGHT. SOME OF THIS SHOULD FALL AS FROZEN PRECIPITATION ACROSS
MAINLY NORTHERN INTERIOR ZONES INTO WEDNESDAY MORNING. NO
SIGNIFICANT HYDROLOGIC IMPACT IS CURRENTLY EXPECTED.
&&
.OKX WATCHES/WARNINGS/ADVISORIES...
CT...NONE.
NY...NONE.
NJ...NONE.
MARINE...SMALL CRAFT ADVISORY FROM 10 AM MONDAY TO 1 AM EST TUESDAY FOR
ANZ330-335-338-340-345-355.
GALE WATCH FROM MONDAY MORNING THROUGH LATE MONDAY NIGHT FOR
ANZ350-353.
&&
$$
SYNOPSIS...JMC/MALOIT
NEAR TERM...JMC/LN
SHORT TERM...JMC/LN
LONG TERM...MALOIT
AVIATION...MET
MARINE...JMC/MALOIT
HYDROLOGY...JMC/MALOIT
AREA FORECAST DISCUSSION
NWS NEW YORK NY
644 PM EST SUN DEC 18 2011
.SYNOPSIS...
A HIGH PRESSURE RIDGE WILL DRIFT OVER THE REGION TONIGHT...AND
OFFSHORE ON MONDAY. A COLD FRONT WILL PASS MONDAY NIGHT. HIGH
PRESSURE BUILDS OVER THE AREA TUESDAY. A WARM FRONT APPROACHES
FROM THE SOUTH TUESDAY NIGHT...THEN LIFTS TO THE NORTH
WEDNESDAY...FOLLOWED BY A COLD FRONT WEDNESDAY NIGHT...AS AN AREA
OF LOW PRESSURE PASSES TO OUR NORTH. HIGH PRESSURE THEN BUILDS IN
TO OUR NORTH THURSDAY THROUGH SUNDAY...AS A COUPLE OF LOW PRESSURE
SYSTEMS PASS TO OUR SOUTH FRIDAY AND THEN LATE NEXT WEEKEND.
&&
.NEAR TERM /UNTIL 10 PM THIS EVENING/...
A 1027 HIGH WAS CENTERED FROM NRN VT INTO CNTRL NY STATE AT 23Z.
SKC ACROSS THE REGION. A FEW HIGH CLOUDS ACROSS WRN NY STATE MAY
APPROACH NWRN ZONES BY 10 PM...OTHERWISE IT WILL REMAIN CLEAR
ACROSS THE CWA. TEMPS WILL CONTINUE TO FALL WITH WINDS DECOUPLING
AND GOING NEARLY CALM.
&&
.SHORT TERM /10 PM THIS EVENING THROUGH TUESDAY NIGHT/...
HIGH PRESSURE RIDGING FROM ERN CANADA TO THE GULF COAST WILL SLOWLY
TRANSLATE EWD OVERNIGHT. WINDS WILL GO CALM AS THE RIDGE TRAVERSES
THE CWA. THIS WILL ALLOW TEMPS TO DROP TO SOME OF THE COLDEST
READINGS OF THE YEAR. ONLY LIMITING FACTOR WILL BE CLOUDS OVER THE
GREAT LAKES INTO WRN PA AS THEY SPREAD EWD TOWARDS THE CWA. WITH
SUBSIDENCE OVER THE CWA HOWEVER...MOST OF THE LOW AND MID CLOUD
POTENTIAL WILL BE MITIGATED...LEAVING MAINLY HIGH CLOUDS OVER THE
AREA TNGT. TEMPS WERE THEREFORE TRENDED TOWARDS THE LOWER GUIDANCE
NUMBERS...AND HAVE TWEAKED READINGS EVEN COLDER THAN GUIDANCE ACROSS
THE PINE BARRENS OF LI. A FEW SINGLE DIGIT LOWS WILL BE POSSIBLE IN
THIS AREA. TEMPS BLW GUIDANCE IN THE CITY AS WELL...AS TEMPS AT
20Z WERE CLOSE TO GUIDANCE LOWS AND A FEW DEGREES SHOULD BE LOST
AFT DARK. SOME WARMING LATE IS POSSIBLE IN THE CITY AND WRN LI AS
LIGHT SW FLOW DEVELOPS ON THE BACK SIDE OF THE HIGH.
LOW PRES OVER ONTARIO WILL RACE EWD ON MON UNDER THE INFLUENCE OF A
STRENGTHENING 120KT H3 JET. AS THE ASSOCIATED COLD FRONT
APPROACHES...THE PRES GRAD WILL TIGHTEN...ALLOWING FOR INCREASING
WSW WINDS DURING THE DAY. SUSTAINED WINDS WILL MAX OUT IN THE
15-20KT RANGE WITH SOME GUSTS TO AROUND 30KT. STRONGEST WINDS WILL
BE ALONG THE S SHORES. 12Z OKX SOUNDING INDICATED 0.14 INCHES OF
PW...SO THE FCST WILL BE KEPT DRY DURING THE DAYTIME HOURS WITH
MOISTURE TRANSPORT VECTORS NOT REACHING THE CWA TIL AROUND 00Z TUE.
TEMPS WARMER THAN SUN DUE TO BETTER MIXING ALL AREAS AND AN ONSHORE
COMPONENT ON THE COASTS.
THE COLD FRONT PASSES MON NGT. 12Z MODELS IN GOOD AGREEMENT WITH
THIS. MOISTURE REMAINS EXTREMELY LIMITED...BUT ENOUGH LAKE MOISTURE
MAY ALLOW FOR A FEW SPRINKLES AND/OR FLURRIES. HAVE RETAINED THIS
WEATHER IN THE GRIDS. BL TOO WARM FOR FLAKES NEAR THE COASTS
INITIALLY...BUT AT THE CWA GETS INTO THE RR QUAD OF THE H3 170 PLUS
KT H3 JET AFT MIDNIGHT...A FEW FLURRIES POSSIBLE POST FRONTAL ACROSS
ALL AREAS. MOS WAS IN GOOD AGREEMENT FOR TEMPS...SO A BLEND WAS
USED.
&&
.LONG TERM /WEDNESDAY THROUGH SUNDAY/...
THE GFS IS MORE PROGRESSIVE THAN THE NAM/ECMWF/SREF WITH THE SYSTEM
IMPACTING THE REGION MID WEEK...AS IS ITS BIAS...SO USED A BLEND OF
THE SLOWER SOLUTIONS TUESDAY THROUGH WEDNESDAY. WEDNESDAY NIGHT
THROUGH CHRISTMAS DAY...THERE ARE QUITE A BIT OF DIFFERENCES BETWEEN
THE GFS AND ECMWF IN HOW THEY HANDLE THE NEXT SYSTEM EJECTING FROM
THE SW U.S. AND ITS INTERACTION WITH THE NORTHERN STREAM. DUE TO
BETTER RUN TO RUN CONSISTENCY AND BETTER OVERALL VERIFICATION IN THE
LONG TERM...LEANED HEAVILY TOWARDS THE ECMWF WEDNESDAY NIGHT THROUGH
SUNDAY.
RIDGING BUILDS INTO THE AREA TUESDAY/TUESDAY NIGHT...THEN SLIDES
OFFSHORE WEDNESDAY AS A SOUTHERN STREAM TROUGH LIFTS INTO THE UPPER
OHIO RIVER VALLEY...THIS TROUGH WILL SUPPORT A SURFACE LOW TRACKING
TO OUR NORTH WEDNESDAY.
TUESDAY SHOULD BE DRY UNDERNEATH THE RIDGE BUILDING IN. OVER RUNNING
SETS UP TUESDAY NIGHT...AHEAD OF A SURFACE AND 850 HPA WARM
FRONT...EXPECT LIGHT PRECIPITATION TO GRADUALLY DEVELOP FROM SW TO
NE FROM TUESDAY NIGHT INTO WEDNESDAY MORNING. LOW LEVEL THERMAL
PROFILES SUPPORT RAIN ACROSS NYC METRO/LONG ISLAND WITH A WINTRY
MIX...INCLUDING POSSIBLY SOME FREEZING RAIN ACROSS THE
INTERIOR...BEFORE CHANGING TO ALL RAIN AS THE WARM FRONT LIFTS TO
THE NORTH WEDNESDAY MORNING. 40-50 KT LOW LEVEL JET MOVES IN BY
WEDNESDAY AFTERNOON SUPPORTING MORE WIDESPREAD RAIN.
THE AFOREMENTIONED TROUGH LIFT JUST OVER THE REGION WEDNESDAY
NIGHT...ALLOWING PRECIPITATION TO TAPER OFF FROM W TO E BY THURSDAY
MORNING - STILL CARRY SLIGHT CHANCE POPS THURSDAY MORNING AS THERE
HAS BEEN SOME UNCERTAINTY IN TIMING OF THE SYSTEM...WITH SOME
SUGGESTIONS IT COULD END UP A TAD SLOWER THAN CURRENTLY FORECAST.
RIDGING BUILDS IN THURSDAY WITH ITS AXIS SLIDING OFFSHORE THURSDAY
NIGHT. FOLLOWING THE ECMWF...IT APPEARS THAT THE SHEARING TROUGH
FORECAST TO LIFT OUT OF BAJA CA WEDNESDAY...APPROACHES BY LATE
THURSDAY NIGHT...THEN CROSSES ON FRIDAY...WITH AN ASSOCIATED
COASTAL LOW PASSING TO THE SOUTH ALONG A STALLED FRONTAL BOUNDARY.
LOW LEVEL THERMAL PROFILES SUGGEST SNOW OR RAIN/SNOW ACROSS NORTHERN
ZONES AND RAIN ACROSS SOUTHERN ZONES BY LATE THURSDAY NIGHT...WITH
PRECIPITATION TRANSITIONING TO ALL RAIN DURING THE DAY ON FRIDAY ON
THE NORTHERN TIER. THERE IS QUITE A BIT OF UNCERTAINTY WITH THIS
SYSTEM...WITH SOME POTENTIAL IT COULD END UP MISSING US ENTIRELY TO
THE SOUTH.
FRIDAY NIGHT AND SATURDAY WILL FEATURE SW FLOW ALOFT...WITH SOME
EMBEDDED SHORTWAVES. THESE WARRANT SLIGHT CHANCE POPS FOR NOW...BUT
MORE THAN LIKELY WILL BE DRY.
THE NEXT POTENTIAL SYSTEM IMPACTS THE REGION LATE CHRISTMAS
EVE/CHRISTMAS DAY...THIS TIME EJECTING FROM NEAR THE FOUR CORNERS
REGION AROUND THURSDAY. LIKE THE SYSTEM FOR FRIDAY...THE SURFACE LOW
WILL TRACK TO THE SOUTH...THE QUESTION IS HOW FAR. FOLLOWING THE
ECMWF...HAVE SLIGHT CHANCE POPS FOR LIGHT SNOW DEVELOPING ACROSS
MOST ZONES LATE SATURDAY NIGHT...AND CONTINUING INTO SUNDAY
MORNING...THEN CHANGING TO RAIN IN THE AFTERNOON. ONCE AGAIN - LOW
CONFIDENCE AT THIS TIME.
NEAR NORMAL TEMPERATURES ARE EXPECTED TUESDAY...THEN ABOVE NORMAL
TEMPERATURES TUESDAY NIGHT THROUGH THURSDAY NIGHT. NEAR NORMAL
TEMPERATURES ARE FORECAST FRIDAY-SUNDAY.
&&
.AVIATION /00Z MONDAY THROUGH FRIDAY/...
HIGH PRESSURE OVER THE AREA DRIFTS SOUTH MONDAY AS A COLD FRONT
APPROACHES.
VFR. NORTHERLY WINDS UNDER 10 KT BECOME WEST TO SOUTHWEST TONIGHT.
GUSTS DEVELOP AFTER 15Z MONDAY AND PEAK IN THE MID AFTERNOON 20 TO
25 KT.
OUTLOOK FOR 00Z TUESDAY THROUGH FRIDAY...
MONDAY NIGHT...VFR. WINDS SHIFT FROM THE SOUTHWEST TO NORTHWEST LATE
BEHIND A COLD FRONT. GUSTY WINDS POSSIBLE LATE.
TUESDAY...VFR.
TUESDAY NIGHT AND WEDNESDAY...SUB VFR IN RAIN...A WINTRY MIX
POSSIBLE INLAND LATE TUESDAY NIGHT. BECOMING VFR WEDNESDAY NIGHT.
THURSDAY...VFR.
FRIDAY...SUB-VFR POSSIBLE.
&&
.MARINE...
LIGHT WINDS TNGT AS HIGH PRES BUILDS OVER THE WATERS. THE HIGH
DRIFTS E OF THE CSTL WATERS MON...ALLOWING FOR A TIGHTENING PRES
GRAD TO DEVELOP THRU THE DAY AS A COLD FRONT APPROACHES FROM THE W.
STRENGTHENING WSW WINDS WILL BE THE RESULT. SCA WILL REMAIN IN
EFFECT FOR ALL WATERS EXCEPT FOR THE ERN OCEAN...WHERE THE GALE
WATCH WILL BE RETAINED. WINDS WEAKEN INVOF THE FRONT
OVERNIGHT...THEN VEER TO THE NW BEHIND THE FRONT EARLY TUE MRNG.
SCA LEVEL SEAS COULD LINGER INTO TUESDAY ON THE FAR EASTERN COASTAL
WATERS...OTHERWISE SUB-SCA CONDITIONS ARE EXPECTED TUESDAY AND
TUESDAY NIGHT. SOUTHERLY FLOW AHEAD OF A STORM SYSTEM
WEDNESDAY...SHOULD AT LEAST BUILD SEAS ON THE COASTAL OCEAN WATERS
TO SCA LEVELS...WITH GUSTY WINDS CONTINUING THEM AT SCA LEVELS INTO
THURSDAY. THERE IS SOME POTENTIAL FOR SCA LEVEL GUSTS ON ALL WATERS
WEDNESDAY-THURSDAY...BUT NOT QUITE CONFIDENT ENOUGH TO GO WITH THIS
IN THE FORECAST AT THIS TIME.
FOR NOW GOING WITH SUB-SCA CONDITIONS ON FRIDAY WITH A COASTAL LOW
PASSING TO THE SOUTH...BUT THERE IS MUCH UNCERTAINTY IN THIS.
&&
.HYDROLOGY...
TRACE AMOUNTS OF PCPN ARE POSSIBLE MON NGT.
THERE IS THE POTENTIAL FOR AROUND A 1/4 TO 1/2 AN INCH OF LIQUID
EQUIVALENT TO FALL OVER THE REGION FROM TUESDAY NIGHT INTO WEDNESDAY
NIGHT. SOME OF THIS SHOULD FALL AS FROZEN PRECIPITATION ACROSS
MAINLY NORTHERN INTERIOR ZONES INTO WEDNESDAY MORNING. NO
SIGNIFICANT HYDROLOGIC IMPACT IS CURRENTLY EXPECTED.
&&
.OKX WATCHES/WARNINGS/ADVISORIES...
CT...NONE.
NY...NONE.
NJ...NONE.
MARINE...SMALL CRAFT ADVISORY FROM 10 AM MONDAY TO 1 AM EST TUESDAY FOR
ANZ330-335-338-340-345-355.
GALE WATCH FROM MONDAY MORNING THROUGH LATE MONDAY NIGHT FOR
ANZ350-353.
&&
$$
SYNOPSIS...JMC/MALOIT
NEAR TERM...JMC
SHORT TERM...JMC
LONG TERM...MALOIT
AVIATION...MET
MARINE...JMC/MALOIT
HYDROLOGY...JMC/MALOIT
AREA FORECAST DISCUSSION
NWS NEW YORK NY
624 PM EST SUN DEC 18 2011
.SYNOPSIS...
A HIGH PRESSURE RIDGE WILL DRIFT OVER THE REGION TONIGHT...AND
OFFSHORE ON MONDAY. A COLD FRONT WILL PASS MONDAY NIGHT. HIGH
PRESSURE BUILDS OVER THE AREA TUESDAY. A WARM FRONT APPROACHES
FROM THE SOUTH TUESDAY NIGHT...THEN LIFTS TO THE NORTH
WEDNESDAY...FOLLOWED BY A COLD FRONT WEDNESDAY NIGHT...AS AN AREA
OF LOW PRESSURE PASSES TO OUR NORTH. HIGH PRESSURE THEN BUILDS IN
TO OUR NORTH THURSDAY THROUGH SUNDAY...AS A COUPLE OF LOW PRESSURE
SYSTEMS PASS TO OUR SOUTH FRIDAY AND THEN LATE NEXT WEEKEND.
&&
.NEAR TERM /UNTIL 10 PM THIS EVENING/...
A 1027 HIGH WAS CENTERED FROM NRN VT INTO CNTRL NY STATE AT 23Z.
SKC ACROSS THE REGION. A FEW HIGH CLOUDS ACROSS WRN NY STATE MAY
APPROACH NWRN ZONES BY 10 PM...OTHERWISE IT WILL REMAIN CLEAR
ACROSS THE CWA. TEMPS WILL CONTINUE TO FALL WITH WINDS DECOUPLING
AND GOING NEARLY CALM.
&&
.SHORT TERM /10 PM THIS EVENING THROUGH TUESDAY NIGHT/...
HIGH PRESSURE RIDGING FROM ERN CANADA TO THE GULF COAST WILL SLOWLY
TRANSLATE EWD OVERNIGHT. WINDS WILL GO CALM AS THE RIDGE TRAVERSES
THE CWA. THIS WILL ALLOW TEMPS TO DROP TO SOME OF THE COLDEST
READINGS OF THE YEAR. ONLY LIMITING FACTOR WILL BE CLOUDS OVER THE
GREAT LAKES INTO WRN PA AS THEY SPREAD EWD TOWARDS THE CWA. WITH
SUBSIDENCE OVER THE CWA HOWEVER...MOST OF THE LOW AND MID CLOUD
POTENTIAL WILL BE MITIGATED...LEAVING MAINLY HIGH CLOUDS OVER THE
AREA TNGT. TEMPS WERE THEREFORE TRENDED TOWARDS THE LOWER GUIDANCE
NUMBERS...AND HAVE TWEAKED READINGS EVEN COLDER THAN GUIDANCE ACROSS
THE PINE BARRENS OF LI. A FEW SINGLE DIGIT LOWS WILL BE POSSIBLE IN
THIS AREA. TEMPS BLW GUIDANCE IN THE CITY AS WELL...AS TEMPS AT
20Z WERE CLOSE TO GUIDANCE LOWS AND A FEW DEGREES SHOULD BE LOST
AFT DARK. SOME WARMING LATE IS POSSIBLE IN THE CITY AND WRN LI AS
LIGHT SW FLOW DEVELOPS ON THE BACK SIDE OF THE HIGH.
LOW PRES OVER ONTARIO WILL RACE EWD ON MON UNDER THE INFLUENCE OF A
STRENGTHENING 120KT H3 JET. AS THE ASSOCIATED COLD FRONT
APPROACHES...THE PRES GRAD WILL TIGHTEN...ALLOWING FOR INCREASING
WSW WINDS DURING THE DAY. SUSTAINED WINDS WILL MAX OUT IN THE
15-20KT RANGE WITH SOME GUSTS TO AROUND 30KT. STRONGEST WINDS WILL
BE ALONG THE S SHORES. 12Z OKX SOUNDING INDICATED 0.14 INCHES OF
PW...SO THE FCST WILL BE KEPT DRY DURING THE DAYTIME HOURS WITH
MOISTURE TRANSPORT VECTORS NOT REACHING THE CWA TIL AROUND 00Z TUE.
TEMPS WARMER THAN SUN DUE TO BETTER MIXING ALL AREAS AND AN ONSHORE
COMPONENT ON THE COASTS.
THE COLD FRONT PASSES MON NGT. 12Z MODELS IN GOOD AGREEMENT WITH
THIS. MOISTURE REMAINS EXTREMELY LIMITED...BUT ENOUGH LAKE MOISTURE
MAY ALLOW FOR A FEW SPRINKLES AND/OR FLURRIES. HAVE RETAINED THIS
WEATHER IN THE GRIDS. BL TOO WARM FOR FLAKES NEAR THE COASTS
INITIALLY...BUT AT THE CWA GETS INTO THE RR QUAD OF THE H3 170 PLUS
KT H3 JET AFT MIDNIGHT...A FEW FLURRIES POSSIBLE POST FRONTAL ACROSS
ALL AREAS. MOS WAS IN GOOD AGREEMENT FOR TEMPS...SO A BLEND WAS
USED.
&&
.LONG TERM /WEDNESDAY THROUGH SUNDAY/...
THE GFS IS MORE PROGRESSIVE THAN THE NAM/ECMWF/SREF WITH THE SYSTEM
IMPACTING THE REGION MID WEEK...AS IS ITS BIAS...SO USED A BLEND OF
THE SLOWER SOLUTIONS TUESDAY THROUGH WEDNESDAY. WEDNESDAY NIGHT
THROUGH CHRISTMAS DAY...THERE ARE QUITE A BIT OF DIFFERENCES BETWEEN
THE GFS AND ECMWF IN HOW THEY HANDLE THE NEXT SYSTEM EJECTING FROM
THE SW U.S. AND ITS INTERACTION WITH THE NORTHERN STREAM. DUE TO
BETTER RUN TO RUN CONSISTENCY AND BETTER OVERALL VERIFICATION IN THE
LONG TERM...LEANED HEAVILY TOWARDS THE ECMWF WEDNESDAY NIGHT THROUGH
SUNDAY.
RIDGING BUILDS INTO THE AREA TUESDAY/TUESDAY NIGHT...THEN SLIDES
OFFSHORE WEDNESDAY AS A SOUTHERN STREAM TROUGH LIFTS INTO THE UPPER
OHIO RIVER VALLEY...THIS TROUGH WILL SUPPORT A SURFACE LOW TRACKING
TO OUR NORTH WEDNESDAY.
TUESDAY SHOULD BE DRY UNDERNEATH THE RIDGE BUILDING IN. OVER RUNNING
SETS UP TUESDAY NIGHT...AHEAD OF A SURFACE AND 850 HPA WARM
FRONT...EXPECT LIGHT PRECIPITATION TO GRADUALLY DEVELOP FROM SW TO
NE FROM TUESDAY NIGHT INTO WEDNESDAY MORNING. LOW LEVEL THERMAL
PROFILES SUPPORT RAIN ACROSS NYC METRO/LONG ISLAND WITH A WINTRY
MIX...INCLUDING POSSIBLY SOME FREEZING RAIN ACROSS THE
INTERIOR...BEFORE CHANGING TO ALL RAIN AS THE WARM FRONT LIFTS TO
THE NORTH WEDNESDAY MORNING. 40-50 KT LOW LEVEL JET MOVES IN BY
WEDNESDAY AFTERNOON SUPPORTING MORE WIDESPREAD RAIN.
THE AFOREMENTIONED TROUGH LIFT JUST OVER THE REGION WEDNESDAY
NIGHT...ALLOWING PRECIPITATION TO TAPER OFF FROM W TO E BY THURSDAY
MORNING - STILL CARRY SLIGHT CHANCE POPS THURSDAY MORNING AS THERE
HAS BEEN SOME UNCERTAINTY IN TIMING OF THE SYSTEM...WITH SOME
SUGGESTIONS IT COULD END UP A TAD SLOWER THAN CURRENTLY FORECAST.
RIDGING BUILDS IN THURSDAY WITH ITS AXIS SLIDING OFFSHORE THURSDAY
NIGHT. FOLLOWING THE ECMWF...IT APPEARS THAT THE SHEARING TROUGH
FORECAST TO LIFT OUT OF BAJA CA WEDNESDAY...APPROACHES BY LATE
THURSDAY NIGHT...THEN CROSSES ON FRIDAY...WITH AN ASSOCIATED
COASTAL LOW PASSING TO THE SOUTH ALONG A STALLED FRONTAL BOUNDARY.
LOW LEVEL THERMAL PROFILES SUGGEST SNOW OR RAIN/SNOW ACROSS NORTHERN
ZONES AND RAIN ACROSS SOUTHERN ZONES BY LATE THURSDAY NIGHT...WITH
PRECIPITATION TRANSITIONING TO ALL RAIN DURING THE DAY ON FRIDAY ON
THE NORTHERN TIER. THERE IS QUITE A BIT OF UNCERTAINTY WITH THIS
SYSTEM...WITH SOME POTENTIAL IT COULD END UP MISSING US ENTIRELY TO
THE SOUTH.
FRIDAY NIGHT AND SATURDAY WILL FEATURE SW FLOW ALOFT...WITH SOME
EMBEDDED SHORTWAVES. THESE WARRANT SLIGHT CHANCE POPS FOR NOW...BUT
MORE THAN LIKELY WILL BE DRY.
THE NEXT POTENTIAL SYSTEM IMPACTS THE REGION LATE CHRISTMAS
EVE/CHRISTMAS DAY...THIS TIME EJECTING FROM NEAR THE FOUR CORNERS
REGION AROUND THURSDAY. LIKE THE SYSTEM FOR FRIDAY...THE SURFACE LOW
WILL TRACK TO THE SOUTH...THE QUESTION IS HOW FAR. FOLLOWING THE
ECMWF...HAVE SLIGHT CHANCE POPS FOR LIGHT SNOW DEVELOPING ACROSS
MOST ZONES LATE SATURDAY NIGHT...AND CONTINUING INTO SUNDAY
MORNING...THEN CHANGING TO RAIN IN THE AFTERNOON. ONCE AGAIN - LOW
CONFIDENCE AT THIS TIME.
NEAR NORMAL TEMPERATURES ARE EXPECTED TUESDAY...THEN ABOVE NORMAL
TEMPERATURES TUESDAY NIGHT THROUGH THURSDAY NIGHT. NEAR NORMAL
TEMPERATURES ARE FORECAST FRIDAY-SUNDAY.
&&
.AVIATION /23Z SUNDAY THROUGH FRIDAY/...
VFR. HIGH PRESSURE REMAINS WEST OF THE AREA TERMINALS.
NORTH-NORTHWEST FLOW WITH SPEEDS OF 8 TO 12 KT WILL GRADUALLY
DIMINISH THIS EVENING TO LESS THAN 10 KT. EXPECT THE WIND DIRECTION
BETWEEN 320 TO 360.
SURFACE HIGH PRESSURE PASSES TO THE EAST TONIGHT WITH MOST TERMINALS
BECOMING LIGHT AND VARIABLE. AT THIS TIME...WINDS WILL GRADUALLY
SHIFT TO THE WEST AND EVENTUALLY THE SOUTHWEST. WIND SPEEDS INCREASE
THROUGHOUT MONDAY MORNING TO 8-12 KT WITH GUSTS INTO THE TEENS AND
LOWER 20S. SPEEDS MAY BE STRONGER AT THE NYC TERMINALS. CLOUD COVER
WILL INCREASE LATE IN THE 30 HOUR TAFS WITH THE APPROACH OF A COLD
FRONT...WITH VFR CIGS EXPECTED.
OUTLOOK FOR 18Z MONDAY THROUGH FRIDAY...
MONDAY AFTERNOON AND MONDAY NIGHT...VFR. STRONG SW FLOW WITH GUST
UP TO 25 KT POSSIBLE. BRIEF PERIOD OF GUSTY NW FLOW LATE AT NIGHT.
TUESDAY AND TUESDAY NIGHT...VFR...TRENDING TOWARD SUB VFR LATE AT
NIGHT.
WEDNESDAY...SUB VFR IN RAIN...BECOMING VFR AT NIGHT.
THURSDAY...VFR.
FRIDAY...SUB-VFR POSSIBLE.
&&
.MARINE...
LIGHT WINDS TNGT AS HIGH PRES BUILDS OVER THE WATERS. THE HIGH
DRIFTS E OF THE CSTL WATERS MON...ALLOWING FOR A TIGHTENING PRES
GRAD TO DEVELOP THRU THE DAY AS A COLD FRONT APPROACHES FROM THE W.
STRENGTHENING WSW WINDS WILL BE THE RESULT. SCA WILL REMAIN IN
EFFECT FOR ALL WATERS EXCEPT FOR THE ERN OCEAN...WHERE THE GALE
WATCH WILL BE RETAINED. WINDS WEAKEN INVOF THE FRONT
OVERNIGHT...THEN VEER TO THE NW BEHIND THE FRONT EARLY TUE MRNG.
SCA LEVEL SEAS COULD LINGER INTO TUESDAY ON THE FAR EASTERN COASTAL
WATERS...OTHERWISE SUB-SCA CONDITIONS ARE EXPECTED TUESDAY AND
TUESDAY NIGHT. SOUTHERLY FLOW AHEAD OF A STORM SYSTEM
WEDNESDAY...SHOULD AT LEAST BUILD SEAS ON THE COASTAL OCEAN WATERS
TO SCA LEVELS...WITH GUSTY WINDS CONTINUING THEM AT SCA LEVELS INTO
THURSDAY. THERE IS SOME POTENTIAL FOR SCA LEVEL GUSTS ON ALL WATERS
WEDNESDAY-THURSDAY...BUT NOT QUITE CONFIDENT ENOUGH TO GO WITH THIS
IN THE FORECAST AT THIS TIME.
FOR NOW GOING WITH SUB-SCA CONDITIONS ON FRIDAY WITH A COASTAL LOW
PASSING TO THE SOUTH...BUT THERE IS MUCH UNCERTAINTY IN THIS.
&&
.HYDROLOGY...
TRACE AMOUNTS OF PCPN ARE POSSIBLE MON NGT.
THERE IS THE POTENTIAL FOR AROUND A 1/4 TO 1/2 AN INCH OF LIQUID
EQUIVALENT TO FALL OVER THE REGION FROM TUESDAY NIGHT INTO WEDNESDAY
NIGHT. SOME OF THIS SHOULD FALL AS FROZEN PRECIPITATION ACROSS
MAINLY NORTHERN INTERIOR ZONES INTO WEDNESDAY MORNING. NO
SIGNIFICANT HYDROLOGIC IMPACT IS CURRENTLY EXPECTED.
&&
.OKX WATCHES/WARNINGS/ADVISORIES...
CT...NONE.
NY...NONE.
NJ...NONE.
MARINE...SMALL CRAFT ADVISORY FROM 10 AM MONDAY TO 1 AM EST TUESDAY FOR
ANZ330-335-338-340-345-355.
GALE WATCH FROM MONDAY MORNING THROUGH LATE MONDAY NIGHT FOR
ANZ350-353.
&&
$$
SYNOPSIS...JMC/MALOIT
NEAR TERM...JMC
SHORT TERM...JMC
LONG TERM...MALOIT
AVIATION...BC
MARINE...JMC/MALOIT
HYDROLOGY...JMC/MALOIT
AREA FORECAST DISCUSSION
NWS ALBANY NY
425 PM EST SAT DEC 17 2011
.SYNOPSIS...
A RIDGE OF HIGH PRESSURE WILL MOVE ACROSS THE REGION
TONIGHT THROUGH SUNDAY AND GIVE US MAINLY DRY AND COLD WEATHER.
SUNDAY WILL FEEL LIKE WINTER...WITH FORECAST HIGH TEMPERATURES
GENERALLY BELOW FREEZING. ON MONDAY...AN APPROACHING COLD FRONT WILL
BRING INCREASING CLOUDS AND BREEZY CONDITIONS WITH MODERATING
TEMPERATURES.
&&
.NEAR TERM /UNTIL 8 PM THIS EVENING/...
UPPER LEVEL TROUGH IS OVER THE REGION. SHORT WAVE MOVING THROUGH
TROUGH CURRENTLY OVER WEST VIRGINIA. THIS SHORTWAVE PRODUCING
SOLID MID LEVEL CLOUD DECK OVER AREA. COLD NORTHWEST FLOW
PRODUCING SNOW SHOWER/FLURRY ACTIVITY OVER GOOD PART OF FORECAST
AREA. SOME CHAMPLAIN EFFECT NOTED OVER WASHINGTON COUNTY WITH
UPSLOPE ACTIVITY OVER TACONICS. HUDSON MOHAWK CONVERGENCE HAS SET
UP WITH NE WINDS AT KGFL AND NW AT KRME. HRRR INDICATES SNOW
SHOWER ACTIVITY CURRENTLY EAST OF HUDSON SHOULD MIGRATE WESTWARD
ACROSS CAPITAL DISTRICT THIS EVENING SO 30 POP IN GRIDS THROUGH 8 PM.
COLD...BLUSTERY CONDITIONS WILL CONTINUE THIS EVENING.
PREVIOUS...
AS OF 1 PM...COLD AIR CONTINUES TO FILTER INTO THE FORECAST AREA
FROM THE NORTH. TEMPERATURES HAVE STARTED TO DROP AT KALB SO WE
HAVE LIKELY REACHED OUR MAXIMUM TEMPERATURES FOR THE DAY FROM
ALBANY NORTH. TO THE SOUTH ANOTHER DEGREE OR TWO UP IS POSSIBLE
BEFORE TEMPS START DROPPING UNTIL AFTER SUNRISE TOMORROW.
LATEST RUC ANALYSIS SHOWS A SHORTWAVE EMBEDDED IN 500MB FLOW OVER
OHIO VALLEY. WAVE SEEMS TO BE DIGGING SOME AS MIDLEVEL CLOUDS ARE
INCREASING AND NOT MOVING EASTWARD. VAD SCATTERERS SHOW LOW CLOUDS
FROM 2000 TO ABOUT 7000FT WITH MID DECK FROM 14000-22000 FEET.
MOHAWK-HUDSON VALLEY CONVERGENCE SCENARIO IN PLACE...BUT AIR IS SO
DRY JUST SOME SCATTERED FLURRIES SHOWING UP ON RADAR. HIGHER RES
MODELS SHOW SOME FLURRIES OR LIGHT SNOW MOVE ACROSS CAPITAL
DISTRICT THIS EVENING. NO ACCUMULATION EXPECTED.
LATEST UPDATE INCLUDES A PRELIMINARY REFRESH OF GRIDS THROUGH 72 HOURS
BASED ON 12Z/NAM AND CURRENT TRENDS. TEMPS A BLEND OF MET/MAV MOS.
&&
.SHORT TERM /8 PM THIS EVENING THROUGH MONDAY NIGHT/...
HIGH PRESSURE RIDGE WILL BUILD IN FROM THE NORTHWEST. WITH A
MAINLY CLEAR SKY AND DIMINISHING WIND...THE STAGE WILL BE SET FOR
GOOD RADIATIONAL COOLING. THE ONLY INGREDIENT MISSING IN MOST
PLACES WILL BE AN EXTENSIVE SNOWPACK. EVEN WITHOUT ONE...MANY
AREAS LOOK TO HAVE THEIR COLDEST NIGHT OF THE WINTER SEASON THUS
FALL. OVERNIGHT LOWS LOOK TO DIP WELL DOWN INTO THE TEENS FROM THE
CAPITAL DISTRICT AND POINTS SOUTHWARD. WELL TO THE NORTH OF THE
MOHAWK RIVER...SINGLE DIGITS WILL BE THE RULE. SOME OF THE COLDEST
AND SNOW COVERED AREAS OF THE ADIRONDACKS ARE FORECAST TO DROP
BELOW ZERO.
ANOTHER SUNNY SUNDAY IS ON TAP (THIS IS AT LEAST THE 4TH IN A ROW).
HIGH PRESSURE WILL REMAIN IN COMMAND. DESPITE ABUNDANT
SUNSHINE...TEMPERATURES WILL STRUGGLE TO REACH FREEZING AT MOST
LOCATIONS.
HIGH PRESSURE WILL SLIP OFFSHORE LATE SUNDAY NIGHT. WARM AIR
ADVECTION COMBINED WITH A SOUTHWEST FLOW OFF LAKE ONTARIO AND EVEN
LAKE ERIE MIGHT PRODUCE SOME LIGHT ENHANCED SNOW SHOWERS ACROSS
OUR ADIRONDACKS OVERNIGHT SUNDAY INTO EARLY MONDAY. WILL CONTINUE
WITH SLIGHT CHANCES IN THOSE AREAS WHILE EVERYONE ELSE REMAINS
COMPLETELY DRY.
BY MONDAY...A SOUTHWESTERLY FLOW TAKES SHAPE AS H850
TEMPERATURES NUDGE ZERO DEG C AHEAD OF ANOTHER FAST MOVING COLD
FRONT. EVEN WITH MORE CLOUDS AROUND...TEMPERATURES LOOK TO
MODERATE FROM THE MID 30S TO LOWER 40S REGION WIDE. THERE STILL
WILL BE A CHANCE OF RAIN OR SNOW SHOWERS...MAINLY TO THE NORTH AND
WEST OF ALBANY AHEAD OF THE COLD FRONT.
&&
.LONG TERM /TUESDAY THROUGH SATURDAY/...
TWO WORDS COME TO MIND WITH RESPECT TO OUR LONG TERM PORTION OF THE
FORECAST...UNCERTAINTY AND TIMING.
THE MAIN CULPRIT TO THIS FORECAST DILEMMA IS CURRENTLY OVER NORTHERN
BAJA CALIFORNIA. ALL GLOBAL MODELS DO AGREE...THIS SYSTEM WILL
EJECT OUT OVER THE SOUTHERN AND CENTRAL PLAINS DURING THE MID WEEK
PERIOD WITH A POTENTIAL PHASING WITH THE NORTHERN STREAM. THIS DOES
SEEM TO SUGGEST WE WILL EXPERIENCE AN OVERRUNNING EVENT THAT COULD
LEAD TO A WINTRY MIXTURE. HOWEVER...TRENDS ARE FOR THE WARM AIR
ADVECTION TO EVENTUALLY ERODE THE COLDER BOUNDARY LAYER FOR MAINLY A
RAIN EVENT FOR THE MID WEEK PERIOD. THEREAFTER...COLDER WEATHER
WITH A CHANCE FOR A SMALLER WAVE TO BRING PERHAPS SOME SNOW TO THE
REGION FOR THE END OF THE WORK WEEK.
DETAILS...
TUESDAY...A RIDGE OF HIGH PRESSURE IS EXPECTED TO CREST OVER THE
REGION WITH DRY YET SEASONABLE CONDITIONS. UPSTREAM UPPER LOW
BEGINS ITS APPROACH TOWARD THE MID-MISSISSIPPI RIVER VALLEY WITH
OVERRUNNING PATTERN UNFOLDING ACROSS THE OHIO VALLEY.
TUESDAY NIGHT INTO WEDNESDAY...OVERRUNNING PATTERN UNFOLDS WITH
CLOUDS ON THE INCREASE ALONG WITH THE CHANCE FOR A WINTRY MIXTURE.
THE ECMWF KEEPS THE BULK OF THE MOISTURE SOUTH OF THE REGION. THE
GFS/DGEX/CMC ARE CONSIDERABLY MORE MOIST AND PROLIFIC WITH THE
DEGREE OF MOISTURE TRANSPORT INTO THE NORTHEAST. THERMAL PROFILES
CONTINUE TO WARM THAT WOULD SUGGEST ANY PRECIP TRANSITIONING TOWARD
MAINLY RAIN.
WEDNESDAY NIGHT...WITH THE EXCEPTION OF THE DGEX...REMAINDER OF THE
GLOBAL MODELS FAVOR THE CONTINUATION OF THE WARM ADVECTION REGIME.
THIS SHOULD KEEP TEMPERATURES TO REMAIN EITHER STEADY OR SLOWLY
CLIMBING TO REDUCE THE THREAT FOR WINTRY TYPE PRECIPITATION. 850MB
TEMPS AVERAGE AOA +4C.
THURSDAY INTO THURSDAY NIGHT...THE UPPER LOW AND SURFACE WAVE ARE
EXPECTED TO BE OFF THE NEW ENGLAND COAST WITH MINIMAL COLD ADVECTION
DUE TO THE PARALLEL FLOW TO THE THERMAL GRADIENT OVER THE REGION.
WE WILL BE WATCHING FOR THE NEXT SOUTHERN WAVE TO ROUND OUT THE BASE
OF THE ELONGATED TROUGH AND BEGIN TO INTERACT WITH AN OPEN GULF OF
MEXICO. HERE...THE ENSEMBLES OFFER A WIDE DEGREE OF SOLUTIONS FOR
THURSDAY NIGHT WHERE A PERIOD OF LIGHT SNOW COULD EVOLVE ACROSS THE
REGION.
FRIDAY...WHATEVER OCCURS THURSDAY NIGHT IS EXPECTED TO BE WELL
OFFSHORE WITH COLD FROPA DURING THE DAY. THE COMBINATION OF
CYCLONIC FLOW ALOFT AND INCREASING LAKE ONTARIO CONTRIBUTION FOR THE
CHANCE OF EITHER RAIN OR SNOW...DEPENDING ON THOSE BOUNDARY LAYER
TEMPS.
OVERALL...WHEN COMPARED TO CLIMATOLOGY...PRECIPITATION AND
TEMPERATURES EITHER AT OR SLIGHTLY ABOVE NORMAL.
&&
.AVIATION /21Z SATURDAY THROUGH THURSDAY/...
VFR CONDITIONS WILL PREVAIL THROUGH AT LEAST THE NEXT 24 HOURS. A
COLD FRONT MOVING SOUTH AND ALMOST THROUGH THE NORTHERN TWO-
THIRDS OF THE FA...WILL SHIFT NORTHWEST WINDS TO NORTH BEHIND IT
WITH SPEEDS AROUND 10 KTS AND GUSTS 15-25 KTS.
WINDS WILL DECREASE TO 5-10 KTS IN THE MID TO LATE
AFTERNOON...FURTHER DIMINISHING TO LIGHT CONDITIONS AT ALL THREE
TERMINALS OVERNIGHT. WINDS WON/T RECOVER TIL LATE SUNDAY
MORNING...ONLY INCREASING TO 4-8 KTS DURING THE DAY.
OVERCAST VFR CIGS WILL CONTINUE THROUGH THE REST OF TODAY. CLOUD
COVER EXPECTED TO BREAK UP OVER NIGHT...WITH SCT TO FEW HIGH
CLOUDS LEFT BY SUNDAY MORNING. OVERALL FAIR WEATHER CONDITIONS
EXPECTED ON SUNDAY.
OUTLOOK...
MON...VFR...NO SIG WX.
MON NIGHT-TUE...VFR...CHC -SHSN/-SHRA.
TUE NIGHT...VFR/MVFR...CHC SNOW.
WED...MVFR/IFR...CHC MIXED PCPN CHANGING TO RAIN.
THU...VFR...NO SIG WX.
&&
.HYDROLOGY...
NO HYDROLOGIC PROBLEMS EXPECTED THROUGH AT LEAST TUESDAY.
THE ONLY PRECIPITATION FORECAST THROUGH TUESDAY ARE SOME SCATTERED
LIGHT SNOW OR RAIN SHOWERS. THERE IS THE POSSIBILITY OF SOME WET
WEATHER WEDNESDAY OR THURSDAY. ENSEMBLE PRECIPITATION FORECASTS
ARE MOSTLY LESS THAN AN INCH OF LIQUID TOTAL THROUGH THE
WEEK...AND THE MULTI-MODEL HYDROLOGIC ENSEMBLE FORECAST SYSTEM
SHOWS NO FLOODING THROUGH THE UPCOMING WEEK. TEMPERATURES ARE NOT
FORECAST TO BE PERSISTENTLY COLD ENOUGH THIS WEEK TO FORM
SIGNIFICANT RIVER ICE.
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...NONE.
NY...NONE.
MA...NONE.
VT...NONE.
&&
$$
SYNOPSIS...SND
NEAR TERM...SND
SHORT TERM...SND
LONG TERM...BGM
AVIATION...KGM
HYDROLOGY...SND
AREA FORECAST DISCUSSION
NWS ALBANY NY
119 PM EST SAT DEC 17 2011
.SYNOPSIS...
A SECONDARY COLD FRONT WILL CONTINUE TO MOVE ACROSS THE
REGION TODAY. THIS WILL BRING A REINFORCING SHOT OF COLD AIR, .WITH
HIGH PRESSURE BUILDING IN OVER FOR THE LATTER PORTION OF THE
WEEKEND. THIS HIGH PRESSURE WILL BRING DRY AND COLD CONDITIONS
TONIGHT AND SUNDAY. AS HIGH PRESSURE MOVES OFFSHORE, A SOUTHERLY FLOW
WILL BRING A MODERATION IN TEMPERATURE FOR MONDAY.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
AS OF 1 PM...COLD AIR CONTINUES TO FILTER INTO THE FORECAST AREA
FROM THE NORTH. TEMPERATURES HAVE STARTED TO DROP AT KALB SO WE
HAVE LIKELY REACHED OUR MAXIMUM TEMPERATURES FOR THE DAY FROM
ALBANY NORTH. TO THE SOUTH ANOTHER DEGREE OR TWO UP IS POSSIBLE
BEFORE TEMPS START DROPPING UNTIL AFTER SUNRISE TOMORROW.
LATEST RUC ANALYSIS SHOWS A SHORTWAVE EMBEDDED IN 500MB FLOW OVER
OHIO VALLEY. WAVE SEEMS TO BE DIGGING SOME AS MIDLEVEL CLOUDS ARE
INCREASING AND NOT MOVING EASTWARD. VAD SCATTERERS SHOW LOW CLOUDS
FROM 2000 TO ABOUT 7000FT WITH MID DECK FROM 14000-22000 FEET.
MOHAWK-HUDSON VALLEY CONVERGENCE SCENARIO IN PLACE...BUT AIR IS SO
DRY JUST SOME SCATTERED FLURRIES SHOWING UP ON RADAR. HIGHER RES
MODELS SHOW SOME FLURRIES OR LIGHT SNOW MOVE ACROSS CAPITAL
DISTRICT THIS EVENING. NO ACCUMULATION EXPECTED.
LATEST UPDATE INCLUDES A PRELIMINARY REFRESH OF GRIDS THROUGH 72 HOURS
BASED ON 12Z/NAM AND CURRENT TRENDS. TEMPS A BLEND OF MET/MAV MOS.
PREVIOUS...
AS OF 930 AM...COLD FRONT HAS PASSED SOUTH OF I90 AND ITS
APPROACHING THE CATSKILLS...MID HUDSON VALLEY AND NW CT. DEWPOINT
DROPS OF 3-5 DEGREES PER HOUR HAVE BEEN OBSERVED AND TEMPERATURES
HAVE EITHER REMAINED STEADY OR SLOWLY FALLING. SOME FLURRIES/LIGHT
SNOW SHOWERS ARE MOVING ACROSS THE CWFA WITH MINIMAL CONTRIBUTION
FROM LAKE ONTARIO. 12Z SOUNDINGS REVEAL THE CAPPING INVERSION WAS
SITUATED AOA 800MB AND FORECAST PROFILES LOWER THROUGH THE DAY.
MAIN UPDATE TO THIS PACKAGE WAS TO REFRESH HOURLY
TEMPS/DEWPOINTS AND HOLD THESE VALUES NEARLY STEADY OR SLOWLY
FALLING FOR THE REMAINDER OF THE DAY... POPS/WX FOR THE SNOW
SHOWERS/FLURRIES WITH A DECREASING TREND THIS AFTERNOON.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH MONDAY/...
HIGH PRESSURE WILL BUILD IN FROM EASTERN CANADA. WITH A MAINLY CLEAR
SKY AND LITTLE OR NO WIND...THE STAGE WILL BE SET FOR GOOD
RADIATIONAL COOLING. THE ONLY INGREDIENT MISSING IN MOST PLACES WILL
BE AN EXTENSIVE SNOWPACK. EVEN WITHOUT ONE...MANY AREAS LOOK TO HAVE
THEIR COLDEST NIGHT OF THE WINTER SEASON THUS FALL. OVERNIGHT LOWS
LOOK TO DIP WELL DOWN INTO THE TEENS FROM THE CAPITAL DISTRICT AND
POINTS SOUTHWARD. WELL TO THE NORTH OF THE MOHAWK RIVER...SINGLE
DIGITS WILL BE THE RULE. SOME OF THE COLDEST AND SNOW COVERED
SHELTERED VALLEY COULD APPROACH ZERO DEGREES!
ANOTHER SUNNY SUNDAY IS ON TAP. HIGH PRESSURE WILL REMAIN IN
COMMAND. DESPITE ABUNDANT SUNSHINE...TEMPERATURES WILL STRUGGLE TO
REACH BACK TO 30...AND TO THE NORTH OF ALBANY WILL ONLY MAKE IT INTO
THE 20S. IF OUR FORECAST PANS OUT...THIS WILL BE THE FIRST
SUBFREEZING DAY IN ALBANY SINCE MARCH 7TH.
HIGH PRESSURE WILL BEGRUDGINGLY SLIP OFFSHORE LATE SUNDAY NIGHT.
DURING THE EARLY PART OF THE EVENING...THE SKY LOOKS TO BE MAINLY
CLEAR AND THE WIND STILL LIGHT. TEMPERATURES WILL DIP DOWN MAINLY
BACK INTO THE TEENS. THEN...AS WARM ADVECTION CLOUDS TEND TO THICKEN
AND A SOUTHERLY BREEZE ENSUES...TEMPERATURES MIGHT STALL OVERNIGHT.
FOR NOW...SINCE THIS IS STILL SEVERAL NIGHTS...WILL FOLLOW THE MORE
TYPICAL DIURNAL CURVE. BOTTOM LINE...ANOTHER COLD NIGHT...BUT NOT AS
MUCH AS SATURDAY OVERNIGHT.
WARM AIR ADVECTION COMBINED WITH A SOUTHWEST FLOW OFF LAKE ONTARIO
AND EVEN LAKE ERIE MIGHT PRODUCE SOME LIGHT ENHANCED SNOW SHOWERS
ACROSS OUR ADIRONDACKS OVERNIGHT SUNDAY INTO EARLY MONDAY. WILL
CONTINUE WITH SLIGHT CHANCES IN THOSE AREAS WHILE EVERYONE ELSE
REMAINS COMPLETELY DRY.
BY MONDAY...A SOUTHERLY FLOW TAKES SHAPE AS H850
TEMPERATURES...WHICH START AROUND -2C...LOOK TO BRIEFLY WARM UP TO
ABOUT +3C...AHEAD OF ANOTHER FAST MOVING COLD FRONT. EVEN WITH MORE
CLOUDS AROUND THAN SUNDAY...TEMPERATURES LOOK TO MODERATE FROM THE
MID 30S TO LOWER 40S REGION WIDE. THERE STILL WILL BE A CHANCE OF
RAIN OR SNOW SHOWERS...MAINLY ACROSS TO THE NORTH AND WEST OF ALBANY
AHEAD OF THE COLD FRONT.
&&
.LONG TERM /MONDAY NIGHT THROUGH FRIDAY/...
UNCERTAINTY IS PLENTIFUL IN THE LONG TERM FORECAST. MODELS AGREE
THAT A COUPLE OF LOW PRESSURE SYSTEMS WILL AFFECT THE REGION BETWEEN
MONDAY NIGHT AND FRIDAY. HOWEVER...THE AGREEMENT ENDS THERE WITH
SIGNIFICANT TIMING AND TRACK DIFFERENCES BETWEEN MODELS...AND EVEN
BETWEEN DIFFERENT RUNS OF THE SAME MODEL. THUS...IT IS HIGHLY LIKELY
THAT THIS FORECAST WILL CHANGE CONSIDERABLY OVER THE NEXT 24 HOURS
AND THERE IS NO NEED TO GET TOO SPECIFIC AT THIS TIME. HAVE CHOSEN
TO BASE THE FORECAST ON THE 00Z GFS FOR NOW WHICH RESULTS IN HIGH
CHANCE POPS TUESDAY NIGHT INTO WEDNESDAY. TEMP PROFILES SUGGEST THAT
A SIGNIFICANT PORTION OF THE PCPN WITH THIS EVENT WILL BE RAIN.
THE NEXT SYSTEM IS FORECAST TO BEGIN TO AFFECT THE REGION ON FRIDAY
AND CONTINUE INTO EARLY NEXT WEEKEND. TEMP PROFILES ARE COLDER WITH
THIS SYSTEM...SO MORE OF THE PCPN WITH THIS SYSTEM IS FORECAST TO BE
SNOW.
ONCE AGAIN THIS LONG TERM PERIOD FEATURES ABOVE NORMAL TEMPS. LOWS
MONDAY THROUGH THURSDAY NIGHTS WILL GENERALLY BE BETWEEN 20 AND 30.
HIGHS TUESDAY WILL BE IN THE UPPER 20S TO LOWER 40S. HIGHS WEDNESDAY
IN THE UPPER 30S AND 40S. MID 30S TO MID 40S THURSDAY...AND MID 30S
TO LOWER 40S FRIDAY.
&&
.AVIATION /18Z SATURDAY THROUGH THURSDAY/...
VFR CONDITIONS WILL PREVAIL THROUGH AT LEAST THE NEXT 24 HOURS. A
COLD FRONT MOVING SOUTH AND ALMOST THROUGH THE NORTHERN TWO-
THIRDS OF THE FA...WILL SHIFT NORTHWEST WINDS TO NORTH BEHIND IT
WITH SPEEDS AROUND 10 KTS AND GUSTS 15-25 KTS.
WINDS WILL DECREASE TO 5-10 KTS IN THE MID TO LATE
AFTERNOON...FURTHER DIMINISHING TO LIGHT CONDITIONS AT ALL THREE
TERMINALS OVERNIGHT. WINDS WON/T RECOVER TIL LATE SUNDAY
MORNING...ONLY INCREASING TO 4-8 KTS DURING THE DAY.
OVERCAST VFR CIGS WILL CONTINUE THROUGH THE REST OF TODAY. CLOUD
COVER EXPECTED TO BREAK UP OVER NIGHT...WITH SCT TO FEW HIGH
CLOUDS LEFT BY SUNDAY MORNING. OVERALL FAIR WEATHER CONDITIONS
EXPECTED ON SUNDAY.
OUTLOOK...
MON...VFR...NO SIG WX.
MON NIGHT-TUE...VFR...CHC -SHSN/-SHRA.
TUE NIGHT...VFR/MVFR...CHC SNOW.
WED...MVFR/IFR...CHC MIXED PCPN CHANGING TO RAIN.
THU...VFR...NO SIG WX.
&&
.HYDROLOGY...
NO SIGNIFICANT HYDROLOGY PROBLEMS ARE EXPECTED THROUGH THE PERIOD.
MAINLY DRY WEATHER EXPECTED THROUGH THE WEEKEND AND MOST OF MONDAY.
A FRONTAL SYSTEM MOVING THROUGH THE REGION MONDAY WILL BRING THE
NEXT CHANCE FOR SOME PRECIP BUT THIS SYSTEM LOOKS TO BE LIGHT WITH
SOME OF FALLING AS SNOW NORTH AND WEST OF ALBANY. THEREFORE RIVERS
WILL CONTINUE TO RECEDE BEFORE ANOTHER STORM MAY AFFECT THE REGION
LATER IN THE WEEK.
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.
&&
.CLIMATE...
2011 SITS IN THIRD PLACE FOR WETTEST YEARS ON RECORD FOR ALBANY
NY. PRECIPITATION RECORDS DATE BACK TO 1826.
1) 56.78 INCHES 1871
2) 55.81 INCHES 1870
3) 51.87 INCHES THROUGH 4 PM DECEMBER 16TH
4) 51.83 INCHES 1850
5) 49.80 INCHES 1827
6) 49.37 INCHES 1878
7) 48.35 INCHES 1843
8) 48.22 INCHES 1848
9) 47.79 INCHES 2008
10) 47.72 INCHES 2005
&&
.ALY WATCHES/WARNINGS/ADVISORIES...
CT...NONE.
NY...NONE.
MA...NONE.
VT...NONE.
&&
$$
SYNOPSIS...HWJIV/SND
NEAR TERM...SND/BGM
SHORT TERM...SND/HWJIV
LONG TERM...GJM
AVIATION...KGM
HYDROLOGY...HWJIV/RCK
CLIMATE...IAA
AREA FORECAST DISCUSSION
NWS COLUMBIA SC
403 AM EST SAT DEC 17 2011
.SYNOPSIS...
WEAK FRONTAL BOUNDARY HAS MOVED JUST EAST OF THE FORECAST AREA AND
WILL CONTINUE TO TRACK AWAY FROM THE AREA TODAY. THIS WILL ALLOW
HIGH PRESSURE ALONG WITH COOLER AND DRIER AIR TO ENTER THE REGION
THROUGH MONDAY. ANOTHER FRONTAL SYSTEM AND CHANCES OF RAIN WILL
MOVE INTO THE REGION ON TUESDAY.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
WEAK FRONTAL BOUNDARY WHICH BROUGHT SOME LIGHT SHOWERS TO THE FAR
NORTHERN MIDLANDS HAS MOVED EAST OF THE FORECAST AREA AND WILL BE
OFFSHORE BY LATE THIS MORNING. THIS WILL BRING HIGH PRESSURE BACK
TO THE REGION ALONG WITH SLIGHTLY COOLER AIR AND SKIES BECOMING
MOSTLY SUNNY. WEAK COLD AIR ADVECTION WILL OFFSET THE INCREASING
SUNSHINE AND PREVENT TEMPERATURES FROM CLIMBING MUCH TODAY...WITH
AFTERNOON HIGHS IN THE MIDDLE 50S NORTH TO THE LOWER 60S IN THE
SOUTHERN MIDLANDS AND CSRA.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH SUNDAY NIGHT/...
HIGH PRESSURE WILL CONTINUE MOVING OVER THE REGION THROUGH THE
WEEKEND AND BE CENTERED OVER THE FORECAST AREA ON SUNDAY
AFTERNOON. THIS WILL RESULT IN THE WEEKEND BEING DOMINATED BY
MOSTLY CLEAR SKIES AND LIGHT WINDS. HIGH TEMPERATURES WILL BE IN
THE UPPER 50S TO LOWER 60S WITH OVERNIGHT LOWS IN THE LOWER 30S
AND SLIGHTLY COOLER IN OUTLYING AREAS.
&&
.LONG TERM /MONDAY THROUGH FRIDAY/...
MODELS HAVE COME INTO BETTER AGREEMENT THROUGH THE LONG
TERM...HOWEVER CONTINUE TO DIFFER ON MAJOR FEATURES FROM WEDNESDAY
ONWARD. OVERALL THE MODELS AGREE THE PATTERN FOR THE LONG TERM
WILL BE MORE ACTIVE WITH LOW PRESSURE SYSTEMS QUICKLY CROSSING THE
REGION. IN GENERAL HAVE INCREASED POPS TUESDAY AND TUESDAY NIGHT
AS MODELS AGREE ON SYNOPTIC PATTERN BUT CONTINUE TO HAVE TIMING
ISSUES WITH THE GFS BEING FASTER AND MORE AMPLIFIED THAN THE
ECMWF. THIS SYSTEM WILL MOVE EAST OF THE AREA LATE WEDNESDAY
AFTERNOON/WEDNESDAY NIGHT WITH THE FRONT STALLING ACROSS THE FL
PENINSULA. THE FRONT WILL MOVE BACK NORTHWARD ACROSS THE REGION
THURSDAY NIGHT/FRIDAY AS THE NEXT SYSTEM MOVES THROUGH. WITH THE
CONTINUED CHANGES IN THE MODELS FROM RUN TO RUN CONFIDENCE REMAINS
LOW FOR WEDNESDAY THROUGH FRIDAY. TEMPERATURES THROUGH THE LONG
TERM WILL GENERALLY BE A COUPLE TO SEVERAL DEGREES ABOVE NORMAL
FOR DAYTIME HIGHS AND OVERNIGHT LOWS.
&&
.AVIATION /09Z SATURDAY THROUGH THURSDAY/...
COLD FRONTAL BOUNDARY APPROACHING KOGB AT 09Z...WILL BE SOUTH OF ALL
TAF SITES BY 10Z. MVFR CIGS AT KCAE/KCUB...SPREADING SOUTHWARD.
LATEST RUC MODEL STILL HAS MVFR CIGS REACHING KAGS/KDNL BY 11Z. CIGS
MAY TEMPORARILY GO BELOW 1000 FEET THROUGH 13Z. WILL NOT MENTION
TAFS SINCE CONFIDENCE IS LOW.
AFTER 15Z EXPECT VFR ALL TAF SITES AS THE BULK OF THE LOW LEVEL
MOISTURE MOVES ON EAST. MAY SEE A PERIOD OF SCT/BKN CLOUDS AROUND
4000 FEET FROM LATE AFTERNOON INTO THE EVENING AS MID LEVEL
DISTURBANCE CROSSES THE REGION.
EXTENDED AVIATION OUTLOOK...MVFR CONDITIONS POSSIBLE TUESDAY NIGHT
INTO WEDNESDAY AS ANOTHER FRONT CROSSES THE AREA.
&&
.CAE WATCHES/WARNINGS/ADVISORIES...
SC...NONE.
GA...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS LINCOLN IL
1118 PM CST FRI DEC 16 2011
.DISCUSSION...
ISSUED 852 PM CST FRI DEC 16 2011
WEAK WEATHER SYSTEM ACRS MINNESOTA AND NORTHERN IOWA TRACKING SE
WITH SOME LIGHT SNOW AND FLURRIES BEING REPORTED OVER PARTS OF
NORTH CENTRAL THRU NE IOWA THIS EVENING. LOOKS AS IF THE BULK OF
THE LIGHT SNOW SHOULD SKIRT JUST NORTH OF THE AREA LATE TONIGHT
THRU SATURDAY MORNING...BUT WILL INCLUDE SOME FLURRIES ROUGHLY
FROM WYOMING SE TO NEAR CHAMPAIGN AND DANVILLE. HI-RES MODELS AND
LATEST RUC SUGGESTS A LITTLE FURTHER SOUTHWARD SHIFT IN THE VORT
TRACK AND MID LEVEL LIFT...RESULTING IN THE ADJUSTMENT TO THE
PRECIP CHANCES LATE TONIGHT THRU SAT MORNING...MAINLY FROM 2 AM
THRU 10 AM ACROSS THE FAR NORTH. ELSEWHERE...FORECAST SEEMS TO
BE IN GOOD SHAPE AS THE INCREASE IN CLOUD COVER SHOULD KEEP TEMPS
FROM FALLING OFF MUCH FURTHER THIS EVENING. SHOULD HAVE THE UPDATED
ZONE FORECAST OUT BY 915 PM.
&&
.AVIATION...
ISSUED 1110 PM CST FRI DEC 16 2011
WEATHER SYSTEM PUSHING ACRS THE NORTHERN PLAINS WILL PUSH JUST
NORTH OF THE TAF SITES LATE TONIGHT INTO SATURDAY MORNING. MAY
SEE A FEW FLURRIES AT BMI AND CMI SATURDAY MORNING BUT IT
APPEARS THE BULK OF ANY ACCUMULATING SNOW WILL REMAIN NORTH
OF OUR AREA. MAY SEE A BRIEF PERIOD OF CIGS BETWEEN 3500-4500
FEET A PIA...BMI AND CMI TOMORROW MORNING...BUT THE REMAINDER
OF THE AREA SHOULD SEE CIGS AOA 5000 FEET. SFC WINDS WILL
GRADUALLY BACK INTO THE SOUTHWEST TONIGHT AND SOUTH TO SOUTHWEST
WINDS SATURDAY MORNING WILL VEER INTO MORE OF A WESTERLY DIRECTION
DURING THE LATE MORNING AND EARLY AFTN HOURS. WINDS TONIGHT WILL
BE LIGHT...AROUND 5 KTS...AND THEN INCREASE TO BETWEEN 10 AND 15
KTS ON SATURDAY.
SMITH
&&
.PREV DISCUSSION...
ISSUED 300 PM CST FRI DEC 16 2011
SHORT TERM...TONIGHT THROUGH MONDAY...
WEAK UPPER SHORTWAVE MOVING INTO MN AND NORTHWESTERN IA IS PRODUCING
A LITTLE LIGHT SNOW/FLURRIES THIS AFTERNOON. THE MAIN ENERGY WITH
THE WAVE...ALONG WITH THE SNOW...WILL BE STAYING NORTH OF THE
FORECAST AREA AS IT PASSES BY TONIGHT. 18Z NAM REFLECTIVITY
SIMULATIONS ALSO KEEP PRECIPITATION TO THE NORTH...BUT NOT BY MUCH.
A FEW FLURRIES CAN BE ADDED IN THE NORTH LATER IF THE CURRENT RADAR
ECHOES TAKE AN UNEXPECTED SOUTHEAST TURN.
OTHERWISE...DRY WEATHER WITH A SLOW WARMING TREND IS EXPECTED
THROUGH THE WEEKEND AS AN AREA OF HIGH PRESSURE MOVES TO THE SOUTH
OF IL AND RESULTS IN WARM ADVECTION WITH INCREASING WEST TO
SOUTHWEST WINDS. INITIAL 850 MB TEMPERATURES AROUND -4C SHOULD RISE
TO 5 ABOVE BY THE END OF THE DAY SUNDAY.
SPLIT UPPER FLOW WILL CONTINUE OVER THE CONUS FOR MUCH OF THIS
PERIOD. A SHORTWAVE IN THE NORTHERN BRANCH WILL MOVE ACROSS SOUTHERN
CANADA WITH AN ATTENDING COLD FRONT COMING SOUTHWARD INTO IL ON
MONDAY. BY THEN...THE SOUTHERN SURFACE HIGH WILL HAVE MOVED EAST
WHICH WILL ALLOW MOISTURE FROM THE GULF TO COME NORTHWARD INTO THE
MIDWEST. BY MONDAY AFTERNOON...THIS MOISTURE WILL BE LIFTED BY THE
APPROACHING COLD FRONT AND RESULT IN AN INCREASED CHANCE OF RAIN.
WILL START OUT WITH CHANCE POPS IN THE MORNING...THEN LIKELY IN THE
AFTERNOON AS THE MOISTURE DEEPENS OVER THE AREA. AT THIS TIME IT
LOOKS LIKE THERE WILL BE SUFFICIENT WARM ADVECTION AHEAD OF THE COLD
FRONT TO PRECLUDE SNOW INTO AT LEAST MONDAY EVENING.
LONG TERM...TUESDAY THROUGH FRIDAY...
AS THE COLD FRONT STALLS OUT OVER THE MIDWEST...PRECIPITATION
CHANCES WILL INCREASE AS AN UPPER LOW NOW OVER BAHA CA COMES
NORTHEASTWARD AND INTERACTS WITH THE FRONT. WILL CONTINUE LIKELY
POPS OVER THE SOUTHERN HALF OF THE AREA CLOSER TO THE FRONT...WHICH
WILL PROVIDE A LOW LEVEL FOCUS. AT THE SAME TIME...COLD AIR WILL
BEGIN COMING INTO NORTH-CENTRAL IL NORTH OF THE FRONT AND GRADUALLY
CHANGE THE RAIN TO SNOW. IT IS STILL UNCLEAR HOW FAR SOUTH THE COLD
AIR WILL COME OR HOW DEEP IT WILL BE AS THE APPROACH OF THE
SOUTHWESTERN LOW WILL CAUSE WARM ADVECTION AT LEAST ALOFT. IF THE
COMBINATION OF CLOUDS/PRECIP KEEPS SURFACE TEMPERATURES COOL
ENOUGH...THEN AN ELEVATED WARM LAYER COULD CAUSE SOME MIXED
PRECIPITATION LATE MONDAY NIGHT INTO TUESDAY. ALTHOUGH THE OVERALL
LONG-RANGE MODEL SOLUTIONS ARE BEGINNING TO COME INTO BETTER
AGREEMENT IN THE OVERALL SYNOPTIC FEATURES... SIGNIFICANT
DIFFERENCES IN THE LOW LEVEL THERMAL STRUCTURE STILL EXIST WHICH
WILL PLAY A SIGNIFICANT ROLE IN PRECIPITATION TYPES. FOR NOW WILL
INDICATE A RATHER SMOOTH TRANSITION FROM RAIN TO SNOW NORTHWEST TO
SOUTHEAST TUESDAY INTO TUESDAY NIGHT AS THE COLD AIR DEEPENS. BY
TUESDAY NIGHT MOST OF THE PRECIPITATION WILL BE MOVING EAST...AND
WEDNESDAY THROUGH THURSDAY LOOK PRETTY MUCH DRY SO FAR. ANOTHER RAIN
OR RAIN/SNOW CHANCE WILL RETURN ON THURSDAY NIGHT/FRIDAY AS SOME OF
THE MODELS INDICATE A SOUTHERN STORM SYSTEM PASSING JUST TO OUR
SOUTH.
&&
.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS NORTHERN INDIANA
640 PM EST SUN DEC 18 2011
.AVIATION...
DETERIORATING CONDITIONS EXPECTED OVERNIGHT INTO MONDAY AS WARM AIR
ADVECTION AND LOW LEVEL MOISTURE INCREASES OVER THE AREA. ISENTROPIC
LIFT WILL INCREASE THROUGH THE NIGHT WITH SATURATION LEADING TO
DEVELOPING/EXPANDING AREA OF STRATUS CLOUDS UPSTREAM INITIALLY. THIS
DEVELOPMENT UNDERWAY ACROSS MO AND HANDLED WELL BY 20Z HRRR CIG PROG
AND MATCHES WELL WITH NAM12 ISENTROPIC DEPICTION. BOTH MODELS
SUGGEST THIS AREA WILL EXPAND AND LOWER THROUGH THE NIGHT AND
INVADE TAF SITES AFTER 08Z AS LOW LEVEL JET INCREASE. SPRINKLES
OR DRIZZLE POSSIBLE UNDERNEATH LOWERING CLOUD DECK THROUGH MONDAY
MORNING. ALSO EXPECT LLWS TO INCREASE THROUGH THE NIGHT WITH
INCREASING LOW LEVEL WIND FIELD. COLD FRONT WILL MOVE INTO AREA FROM
THE NORTH IN THE AFTERNOON...PASSING KSBN AROUND 18Z AND KFWA 21Z.
ADDITIONAL LOW LEVEL MOISTURE ALONG AND BEHIND THIS FRONT SUGGEST
ANOTHER PERIOD OF DRIZZLE OR LIGHT SHOWERS WITH MVFR TO IFR CIGS IN
ITS WAKE.
&&
.SHORT TERM...TONIGHT THROUGH MONDAY NIGHT
POTENTIAL OF STRATUS REDEVELOPMENT/LIGHT PRECIP OVERNIGHT...AND
CHANCES OF PRECIP MONDAY/MONDAY NIGHT WILL BE THE MAIN FORECAST
ISSUES FOR THE SHORT TERM.
UPPER LEVEL HEIGHT RISES WILL CONTINUE TO BUILD EASTWARD ACROSS THE
GREAT LAKES REGION THIS EVENING WHICH WILL ALLOW SKIES TO CLEAR
ACROSS THE FAR NORTHEAST LATE THIS AFTERNOON. A STRENGTHENING LOW
LEVEL HEIGHT GRADIENT ASSOCIATED WITH DEEPENING NORTHERN STREAM
SYSTEM/SURFACE LOW WILL ALLOW A FAIRLY STRONG SFC PRESSURE GRADIENT
TO PERSIST OVERNIGHT. CONTINUED LOW LEVEL WARM ADVECTION AND THIS
STRENGTHENING GRADIENT SHOULD SUPPORT MINS IN THE EVENING NOT
DROPPING TOO FAR FROM CURRENT READINGS...WHICH SHOULD BE FOLLOWED BY
A STEADY OR SLOWLY RISING TEMPERATURE TREND DURING THE OVERNIGHT
HOURS. SHORT RANGE MODELS HAVE BEEN FAIRLY CONSISTENT IN BRINGING
PREFRONTAL LOW LEVEL THETAE RIDGE ACROSS WESTERN PORTIONS OF THE
FORECAST AREA AFTER 06Z. A FAIRLY DRY MID LEVEL MOISTURE PROFILE
SHOULD PERSIST THROUGH THE NIGHTTIME HOURS...ALTHOUGH WITH SOME
MID/UPPER LEVEL MOISTENING ASSOCIATED WITH NORTHERN STREAM SHORT
WAVE...MOISTURE PROFILES SHOULD BE SUFFICIENT FOR SOME SPRINKLES OR
SCATTERED LIGHT RAIN SHOWERS TOWARD MORNING. GIVEN SHALLOW NATURE OF
BETTER MOISTURE...MAY EVEN BE MORE OF A PATCHY DRIZZLE SCENARIO AND
WITH CONFIDENCE STILL LOW ON MEASURABLE PRECIP OVERNIGHT HAVE JUST
MENTIONED SCT SPRINKLES AFTER 09Z.
ON MONDAY...ASSOCIATED COLD FRONTAL BOUNDARY WITH THIS MORE
PROGRESSIVE NORTHERN STREAM TROUGH WILL APPROACH NORTHERN SECTIONS
OF THE FORECAST AREA BY AFTERNOON. THIS INCREASED FRONTAL FORCING
DURING THE DAY SHOULD SUPPORT GREATER -RA THREAT...PARTICULARLY
ACROSS EASTERN HALF OF THE AREA BASED ON EXPECTED PLACEMENT OF LOW
LEVEL THETAE RIDGE AND HAVE MAINTAINED THE WEST TO EAST CHANCE POP
GRADIENT MONDAY. SFC FRONT SHOULD STALL SOUTH OF THE AREA MONDAY
EVENING...WITH ATTENTION TURNING TO WEAKER SHORT WAVES EJECTING OUT
OF SOUTHERN STREAM CUT OFF UPPER LOW. AN INCREASING OVERRUNNING/LOW
LEVEL FRONTALLY INDUCED PRECIP THREAT SHOULD EVOLVE MONDAY
NIGHT...ESPECIALLY LATE. LARGE SCALE SYNOPTIC SUPPORT ALSO SHOULD BE
ON THE INCREASE IN THE RIGHT ENTRANCE REGION OF GREAT LAKES UPPER
JET STREAK. PROFILES SHOULD REMAIN WARM ENOUGH FOR ALL RAIN IN THE
EXTREME SOUTH WHERE HAVE KEPT LIKELY POPS...TRANSITIONING TO HIGH
CHANCE RAIN/SNOW NORTH OF THIS AREA INTO CENTRAL PORTIONS OF THE
FORECAST AREA. MOISTURE CONCERNS FURTHER NORTH OF THE FRONT ACROSS
FAR NORTHERN SECTIONS OF FORECAST AREA CONTINUE TO PRECLUDE ANY
PRECIP MENTION AT THIS TIME ACROSS THESE AREAS. DEPENDING ON EXACTLY
WHERE THIS FRONT LAYS OUT...CANNOT RULE OUT THE POSSIBILITY OF SOME
LIGHT SNOW ACCUMULATIONS SOMEWHERE ACROSS THE SOUTHERN HALF OF THE
AREA LATE MONDAY NIGHT.
&&
.LONG TERM... / TUESDAY THROUGH SUNDAY /
...PROGRESSIVE/ACTIVE SPLIT FLOW REGIME TO CONTINUE THIS PERIOD WITH
TEMPS GENERALLY AOA NORMAL...
12Z MODEL SUITE REMAINED CONSISTENT IN EJECTING THE SLOW MOVING
SOUTHERN STREAM CLOSED UPPER LOW INTO THE CENTRAL PLAINS BY
TUESDAY...EVENTUALLY OPENING INTO THE SOUTHERN GREAT LAKES BY
WEDNESDAY. HEIGHT FALLS ASSOCIATED WITH THIS FEATURE WILL ELICIT A
MODEST LOW LVL RESPONSE WITH INCREASING ISENTROPIC ASCENT OVER A
DEEPENING WARM FRONT THAT WILL BE JUST SOUTH OF THE FA TO
START THE PERIOD. GFS/NAM 300K CHARTS REVEAL NEARLY 20-30 KNOTS OF
CROSS ISOBARIC FLOW TUESDAY MORNING...INCREASING TO AROUND 40 KNOTS
BY TUESDAY AFTERNOON/EVENING WITH A 6 G/KG TAP AND REDUCED CPD`S
(LESS THAN 10 MB). THIS SHOULD ALLOW PRECIPITATION TO EXPAND NWD
INTO THE AREA ON TUESDAY...WITH PTYPE LIKELY STARTING OUT AS A
PERIOD OF WET SNOW. SOME AREAS COULD SEE AROUND AN INCH OF SNOW
ACCUMULATION BEFORE A CHANGEOVER TO RAIN FROM SW TO NE DURING THE
DAY. ALSO CANNOT RULE OUT A BRIEF PERIOD OF FREEZING RAIN DURING THE
CHANGEOVER PER DRY EASTERLY FEED UNDER SFC HIGH. RAISED POPS DURING
THIS TIME GIVEN RELATIVELY CONSISTENT MODEL SIGNALS. OPENING/FILLING
UPPER LOW WILL MOVE THROUGH THE AREA LATE TUESDAY NIGHT INTO
WEDNESDAY WITH GOOD CHANCES FOR MEASURABLE RAINFALL AS MID LVL
DEFORMATION FORCING SWINGS THROUGH. THE MAIN CONCERN HERE WILL BE
THE THREAT FOR RENEWED RIVER FLOODING...ALTHOUGH RAINFALL AMOUNTS
ARE NOT LOOKING AS HEAVY AS PREVIOUS EVENTS.
BEYOND WEDNESDAY...12Z MODEL SUITE FAVORED A MEAN POSITIVELY TILTED
AND FRACTURED TROUGH CENTERED FROM THE NORTHERN PLAINS SWWD INTO THE
EASTERN FOUR CORNERS...WITH A LINGERING SE CONUS RIDGE. GUIDANCE
CONTINUES TO EJECT A COUPLE LOW AMPLITUDE SRN STREAM WAVES FROM THE
SRN PLAINS TO THE EAST COAST IN FAST SW FLOW ALOFT LATE THIS WEEKEND
INTO THE HOLIDAY WEEKEND. ATTM...DEEPER MOISTURE AND BETTER CHANCES
FOR PRECIP ALONG WAVY FRONT LOOKS TO REMAIN SOUTH AND EAST OF THE
AREA. GIVEN THIS WILL CONTINUE TO CARRY ONLY SLIGHT CHANCE POPS THIS
FAR NORTH (FOR LIGHT SNOW SHOWERS) BOTH THURSDAY NIGHT AND SATURDAY
NIGHT/SUNDAY GIVEN PROGGED TIMING OF AFOREMENTIONED IMPULSES.
&&
.IWX WATCHES/WARNINGS/ADVISORIES...
IN...NONE.
MI...NONE.
OH...NONE.
LM...GALE WARNING FROM 7 PM THIS EVENING TO 7 AM EST MONDAY FOR
LMZ043-046.
&&
$$
SHORT TERM...MARSILI
LONG TERM...STEINWEDEL
AVIATION...LASHLEY
AREA FORECAST DISCUSSION
NWS NORTHERN INDIANA
1236 AM EST SAT DEC 17 2011
.AVIATION...
PREVIOUS TAFS STILL IN TRACK AS COMBINATION OF CLIPPER SYSTEM
MOVING THROUGH MINNESOTA ATTM AND SOME ENHANCEMENT FROM LAKE MI
SET THE STAGE FOR PERIOD OF RENEWED MVFR CONDITIONS AT KSBN AND TO
A LESSER EXTENT KFWA. LAKE EFFECT CLOUD COVER HAS HELD STRONG WITH
LEADING EDGE SITTING JUST TO THE WEST OF BOTH SITES. CIGS HAVE
SLOWLY EDGE UPWARD NOW SITTING RIGHT AROUND 3000 FT. HIGH
CONFIDENCE IN CIGS DROPPING BACK INTO MVFR RANGE SATURDAY MORNING
WITH VSBYS IMPACTED AS WELL AT KSBN. UPSTREAM OBSERVATIONS HAVE
GENERALLY BEEN FROM 3 TO 5 SM IN AREAS OF LIGHT SNOW WITH A FEW
POCKETS OF 1SM OR LESS AT TIMES. GIVEN LAKE CONTRIBUTION IN THE 12
TO 18Z SAT TIME FRAME...VSBYS LOWER THAN 2 MILES WILL BE POSSIBLE.
WILL ADJUST FURTHER WITH 12Z TAFS AFTER LOOK AT NEWEST HIGH RES
MODELS. AT KFWA...MAIN SNOWFALL AND LOWEST CONDITIONS MAY REMAIN
JUST TO THE NORTH. CONTINUED MVFR CIG FOR A PERIOD DURING THE DAY.
AS SYSTEM QUICKLY DEPARTS BY LATE AFTERNOON AND FLOW BECOMES MORE
SW WITH TIME...CLOUDS SHOULD PUSH OUT OVERNIGHT WITH IMPROVING
FLGT CONDITIONS.
&&
.PREV DISCUSSION... /ISSUED 655 PM EST FRI DEC 16 2011/
UPDATE...
18Z MODEL DATA ALONG WITH LATEST RUC ANALYSIS SUGGEST SOME CHANGES
IN ORDER FOR FORECAST. MODELS CONTINUE TO TREND TOWARD A STRONGER
SHORT WAVE WITH POTENT 120 KNOT JET MAX DIGGING INTO THE REGION
SATURDAY MORNING. ISENTROPIC LIFT AND SYNOPTIC MOISTURE LACKING SO
ONLY EXPECTING FLURRIES OR VERY LIGHT SNOW SHOWERS AWAY FROM LAKE
MICHIGAN. HOWEVER...PER LATEST MODEL DATA...A WINDOW EXISTS SATURDAY
MORNING FOR SOME LAKE ENHANCEMENT ACROSS NORTHERN INDIANA AND
SOUTHERN LOWER MICHIGAN AND MODELS SEEM TO BE PICKING UP ON THIS.
NAM12 SHOWING LAKE PLUME DEVELOPING TOWARD 12Z WITH 925-850MB OMEGA
INCREASING FROM 12-18Z WITH DELTA T VALUES IN MID TEENS COINCIDENT
WITH SYNOPTIC SHORT WAVE AND DEEPENING MOISTURE COLUMN. DGZ LOOKS TO
BE SATURATED WITH STRONGEST LIFT JUST REACHING THIS LEVEL BRIEFLY.
COULD PRODUCE A QUICK PERIOD OF LAKE ENHANCED SNOW. WILL BE
INCREASING POPS TO AT LEAST HIGH CHANCE IN THE NORTH WITH THIS
UPDATE. 18Z MODEL DATA SOMETIMES BECOMES OVERLY AGGRESSIVE SO
WOULD LIKE TO ALLOW LOOK AT 00Z DATA BEFORE INCREASING ANY FURTHER
ESPECIALLY GIVEN LACK OF GOOD SYNOPTIC SCALE LIFT AND MOISTURE WITH
DRY LOWER LEVELS TO OVERCOME INITIALLY. ACCUMS WOULD LIKELY BE AN
INCH
TO POSSIBLY TWO IN LAKE EFFECT AREAS WHERE ENHANCEMENT POTENTIAL
WOULD OBVIOUSLY BE GREATEST. OUTSIDE OF THIS AREA LIKELY JUST A
DUSTING OR LESS. UPDATE OUT SHORTLY.
PREV FORECAST...
SHORT TERM... / TONIGHT THROUGH SATURDAY NIGHT /
LATEST VIS SAT SHOWING LAKE INDUCED CLOUD DECK HANGING TOUGH OVER
THE NORTHERN HALF OF THE CWA THIS AFTERNOON. SOUTHERN EDGE
GRADUALLY ERODING AND EXPECT THIS TREND TO CONTINUE. SFC HIGH
PRESSURE RIDGE EXTENDING DOWN THE NORTHERN PLAINS AND INTO THE MID
MISSISSIPPI VALLEY WILL MAKE A LITTLE EASTWARD PROGRESS THIS
EVENING...BUT MID LEVEL NW FLOW PATTERN WILL BE MAIN FOCUS IN THE
SHORT TERM. MODELS ARE NOW TRENDING TO A BIT MORE POTENT SHORT
WAVE DROPPING DOWN INTO THE REGION...WITH ADDITIONAL UPPER LEVEL
SUPPORT FROM FAVORABLE JET DYNAMICS. AS USUAL IN NW FLOW...MODELS
SHOWING DIFFERENCES IN TIMING/PLACEMENT/INTENSITY...SO FOR NOW
WILL NOT STRAY TOO FAR FROM GOING FORECAST. WILL KEEP HIGH CHANCE
POPS WITH LIGHT ACCUMS GOING IN THE NORTH AND EXPAND TO 12 HOUR
TIME PERIOD FROM 18Z SAT TO 06Z SUN TO ACCOUNT FOR TIMING
DISCREPANCIES. TEMPS EXPECTED TO BE NEAR CLIMO WITH M30S
HIGHS/M20S LOWS.
LONG TERM... / SUNDAY THROUGH FRIDAY /
PROGRESSIVE/ACTIVE PATTERN WILL CONTINUE IN ABSENCE OF ANY TRUE HIGH
LATITUDE BLOCKING AS POS AO/NAO REGIME CONTINUES THIS PERIOD. THIS
SHOULD RESULT IN A CONTINUATION OF ABOVE NORMAL TEMPS AND
PRECIPITATION NEXT SEVERAL WEEKS.
SUNDAY STILL LOOKS LIKE A DRY DAY WITH TEMPS A LITTLE ABOVE NORMAL
PER HEIGHT RISES AND DEVELOPING LOW LVL ANTICYCLONIC FLOW. 12Z
MODELS CONTINUED TO SHOW A RATHER POTENT NORTHERN STREAM SHORTWAVE
TRAVERSING SOUTH-CENTRAL AND SOUTHEAST CANADA SUNDAY INTO
MONDAY...FORCING A FRONTAL BOUNDARY SEWD INTO THE SRN GREAT LAKES OR
OH VALLEY BY LATE MONDAY/TUESDAY. THIS WILL BE COINCIDENT WITH A SRN
STREAM CLOSED LOW (NOW OVER NRN BAJA PER AFTN WATER VAPOR) FINALLY
GETTING KICKED OUT TOWARDS THE CENTRAL PLAINS AND MID MS VALLEY BY
EARLY NEXT WEEK. THIS APPROACHING POSITIVE PV ANOMALY WILL SUPPORT
BACKING WINDS AND INCREASING ISENTROPIC LIFT...WHICH WHEN COMBINED
WITH INCREASING DIFFLUENCE ALOFT WILL ALLOW THE BAROCLINIC ZONE TO
STALL AND DEEPEN EITHER OVER OR JUST SOUTH OF THE FA DURING THIS
TIME. THE RESULT SHOULD BE AN EXPANDING AREA OF LGT/MOD PRECIP INVOF
THIS FRONTAL CIRCULATION. AS EXPECTED MODELS DO DIFFER WITH TIMING
AND PLACEMENT THIS FAR IN ADVANCE WITH SOME GUIDANCE SETTING UP THIS
BAROCLINIC ZONE AND RESULTING PRECIP WELL SOUTH OF THE FA MONDAY
NIGHT INTO TUESDAY MORNING. GIVEN THIS UNCERTAINTY AND SPREAD WITHIN
GUIDANCE WILL RETAIN CHC POPS...HIGHEST SOUTH. PRECIP SHOULD MAINLY
BE IN THE FORM OF RAIN...WITH SOME WET SNOW POSSIBLE ON THE FAR NRN
FRINGE OF THE PRECIP SHIELD LATE MONDAY NIGHT INTO TUESDAY.
A MODEL CONSENSUS FINALLY EDGES THE FILLING/WEAKENING SRN STREAM
WAVE THROUGH THE AREA LATE TUESDAY AFTN INTO TUESDAY NIGHT...WHEN
LIGHT PRECIPITATION MAY LINGER ACROSS THE AREA AS MID LVL
DEFORMATION FORCING SWINGS THROUGH. THERE COULD BE A NARROW BAND OF
SNOW ON THE NW FRINGE OF THIS SYSTEM...BEST CHANCES ACROSS OUR
NORTHWEST ZONES. ATTM NOT EXPECTING MUCH IN THE WAY OF
ACCUMULATION. THE FA WILL DRY OUT BEHIND THIS SHORTWAVE WEDNESDAY
INTO THURSDAY.
&&
.IWX WATCHES/WARNINGS/ADVISORIES...
IN...NONE.
MI...NONE.
OH...NONE.
LM...NONE.
&&
$$
SHORT TERM...LOGSDON
LONG TERM...STEINWEDEL
AVIATION...FISHER
UPDATE...LASHLEY
AREA FORECAST DISCUSSION
NWS INDIANAPOLIS IN
1155 PM EST FRI DEC 16 2011
.UPDATE...
THE AVIATION SECTION HAS BEEN UPDATED BELOW
&&
.SYNOPSIS...
A QUICK MOVING UPPER LEVEL DISTURBANCE WILL MOVE ACROSS THE LOWER
GREAT LAKES ON SATURDAY...AND MAY BRING A FEW FLURRIES TO NORTHERN
PORTIONS OF THE FORECAST AREA. OTHERWISE...EXPECT DRY WEATHER AS HIGH
PRESSURE ACROSS THE PLAINS SETTLES INTO THE SOUTHERN STATES AND OHIO
VALLEY BY LATE WEEKEND. THEN...A COLD FRONT IS EXPECTED TO DROP
SOUTHEAST ACROSS CENTRAL INDIANA ON MONDAY BEFORE STALLING NEAR
THE OHIO RIVER AS A WAVE DEVELOPS ALONG THE SOUTHERN EDGE OF THE
FRONT ACROSS THE SOUTHERN PLAINS. THIS WAVE WILL THEN LIFT
NORTHEAST ALONG THE FRONT AND ACROSS THE OHIO VALLEY TUESDAY
NIGHT. THIS WILL RESULT IN A RAINY PERIOD STARTING MONDAY AND
ENDING EARLY WEDNESDAY. THEN...HIGH PRESSURE WILL ALLOW FOR A DRY
WEDNESDAY NIGHT AND THURSDAY BEFORE A SOUTHERN PLAINS SYSTEM
BRINGS A CHANCE OF RAIN OR SNOW ON THURSDAY NIGHT AND FRIDAY.
TEMPERATURES SHOULD REMAIN NEAR NORMAL TO SLIGHTLY ABOVE NORMAL
THROUGH NEXT WEEK.
&&
.NEAR TERM /OVERNIGHT/...
STRATOCU CONTINUES TO BE RATHER STUBBORN IN DEPARTING EASTERN
PORTIONS OF THE FORECAST AREA. WITH LOW LEVEL FLOW LARGELY OUT OF
THE N/NW...AM BECOMING LESS OPTIMISTIC THAT THESE CLOUDS WILL
COMPLETELY SCOUR OUT OF THE FORECAST AREA BEFORE RAPIDLY
APPROACHING MID AND HIGH LEVEL CLOUDS EXPAND INTO THE REGION FROM
THE WEST AFTER MIDNIGHT. HAVE THEREFORE BEEFED UP CLOUD COVERAGE
QUITE A BIT FOR MUCH OF THE REST OF THE NIGHT...WITH MANY
LOCATIONS NORTH AND EAST OF THE INDY METRO REMAINING MOSTLY
CLOUDY. MADE MINOR TWEAKS TO TEMPS OVERNIGHT BUT WITH CURRENT
TEMPS ALREADY IN THE UPPER 20S AND LOWER 30S...FORECAST LOWS IN
THE MID 20S LOOK TO BE ON TRACK EVEN WITH THE INCREASE IN CLOUD
COVER.
ZONE AND GRID UPDATES OUT.
&&
.SHORT TERM /SATURDAY THROUGH MONDAY/...
MAIN CHALLENGE TO THE SHORT TERM WILL BE CLOUD COVER...TEMPERATURES
AND TIMING OF RAIN BACK INTO CENTRAL INDIANA.
MODELS HAVE SOME DIFFERENCES BUT NOTHING REAL DRAMATIC REGARDING
MAJOR SYNOPTIC FEATURES IN THE SHORT TERM. SATURDAY WILL START OFF
WITH SOME MID AND HIGH CLOUDS AROUND ESPECIALLY NORTHEAST SECTIONS
AS A SHORT WAVE AND ASSOCIATED MOISTURE DROP SOUTHEAST ACROSS THE
LOWER GREAT LAKES IN THE FAST NORTHWEST FLOW ALOFT. MODEL RUNS
THIS EVENING SHOWING A BIT MORE IN THE WAY OF ISENTROPIC LIFT
PASSING THROUGH NORTHERN FORECAST AREA AND MOST RECENT HRRR DATA
INDICATING MAY SEE A PERIOD WITH FLURRIES OR VERY LIGHT SNOW
SHOWERS GRAZE FAR NORTHERN FORECAST AREA THROUGH 18Z SATURDAY.
IN THE WAKE OF THE SHORT WAVE...SKIES SHOULD BECOME MOSTLY CLEAR
SATURDAY NIGHT AND SUNDAY IN SUBSIDENCE IN PERSISTENT FAST
NORTHWEST FLOW ALOFT AND WITH SURFACE HIGH PRESSURE SLIDING EAST
ACROSS THE SOUTHERN STATES AND OHIO VALLEY. FINALLY...A COLD FRONT
WILL SLIDE SOUTHEAST ACROSS NORTHERN INDIANA ON MONDAY WHICH
SHOULD BRING A CHANCE FOR RAIN ESPECIALLY ACROSS OUR NORTHERN
COUNTIES CLOSER TO THE FRONT.
BASED ON LOW LEVEL THERMAL PROGS WITH 850 MILLIBAR TEMPERATURES
CLIMBING TO 2 TO 4 DEGREES CELSIUS BY LATE SUNDAY AND CLOUD
COVER...GOING WITH THE WARMER NAM MOS FOR TEMPERATURES.
&&
.LONG TERM /MONDAY NIGHT THROUGH FRIDAY/...
MODELS HAVE COME INTO BETTER AGREEMENT WITH EJECTION OF SYSTEM FROM
THE SOUTHWEST USA EARLY IN THE EXTENDED...BUT CONTINUE TO DIFFER
SOME LATER IN THE EXTENDED LIKE THEY HAVE BEEN DOING. GIVEN THIS THE
ALL-BLEND INITIALIZATION LOOKS GOOD ENOUGH FOR THE MOST PART
THROUGHOUT THE EXTENDED.
TEMPERATURES WILL RUN NEAR OR ABOVE AVERAGE FOR THE MOST PART. 00Z
ECMWF AND 12Z GFS BOTH AGREE THAT TUESDAY NIGHT SHOULD REMAIN AT
LEAST JUST WARM ENOUGH FOR ALL RAIN. WILL REMOVE SNOW MENTION
TUESDAY NIGHT AND WEDNESDAY.
WITH THE UNCERTAINTY WITH POPS FOR THURSDAY NIGHT INTO FRIDAY KEPT
POPS LOW AND MENTIONED CHANCE OF RAIN OR SNOW WITH MARGINAL
TEMPERATURES.
&&
.AVIATION /DISCUSSION FOR THE 17/06Z TAF ISSUANCE/...
LOW LEVEL CLOUDS CONTINUE TO BE PERSISTENT AT KIND AND KBMG...AND
REMAIN JUST BELOW VFR CATEGORY AT THIS TIME. HOWEVER...LOW CLOUDS
SHOULD SCATTER OUT BY SAT 09Z AND CEILINGS WILL BECOME VFR
CATEGORY AT ALL TAF SITES. THEY WILL THEN STAY AT VFR CATEGORY FOR
ENTIRE TAF PERIOD DESPITE INCREASED CLOUD COVERAGE IN THE MID AND
HIGH LEVELS DUE TO A DISTURBANCE PASSING OVER THE GREAT LAKES
REGION ON SAT MORN AND AFTERNOON. WINDS WILL INITIALLY BE
WEST/NORTHWESTERLY AND THEN BACK TO THE SOUTHWEST LATE IN TAF
PERIOD. THEY WILL NOT HAVE AN IMPACT ON OPERATIONS THOUGH WITH
SUSTAINED SPEEDS OF ONLY 4 TO 8 KTS.
&&
.IND WATCHES/WARNINGS/ADVISORIES...NONE.
&&
$$
SYNOPSIS...MK/RYAN
NEAR TERM...RYAN
SHORT TERM...MK/RYAN
LONG TERM....CS
AVIATION...TDUD
AREA FORECAST DISCUSSION
NWS QUAD CITIES IA IL
1212 PM CST SAT DEC 17 2011
.AVIATION...
STORM SYSTEM WHICH BROUGHT EARLY AM SNOW TO NORTHEAST IA AND NORTHERN
IL HAS MOSTLY EXITED REGION. WEAK SFC LOW PASSING NEAR KDBQ
EARLY THIS AFTN AND MOVING EWD... WITH BAND OF LOW CLOUDS WITH
LOW VFR TO HIGH MVFR CIGS IN WAKE TO EXIT KDBQ AND KMLI TERMINALS
PRIOR TO SUNSET LEAVING BEHIND MAINLY CLEAR SKIES. WEAK SFC RIDGE
WILL THEN PASS OVRNGT WITH SOME RADIATION FOG LOOKING MORE LIKELY AS
CROSSOVER TEMPS BREACHED. IN GENERAL MVFR VSBYS WITH ANY FOG WITH SOME
IFR VSBYS POSSIBLE ESPECIALLY SNOW COVERED AREAS NORTHEAST IA INTO
NORTHERN IL. WINDS WLY 5-10 KTS BECOMING LIGHT SW TNGT THEN INCREASING
FROM SW AT 10-20 KTS DURING DAY SUN AS SFC RIDGE MOVES EAST AND PRESSURE
GRADIENT INCREASES.
&&
.PREV DISCUSSION... /ISSUED 309 AM CST SAT DEC 17 2011/
SYNOPSIS...
ALOFT...THE LONG WAVE PATTERN IS MARKED BY SPLIT FLOW...WITH A
CUT-OFF LOW OVER LOS ANGELES WHILE THE MIDWEST AND NORTHEAST U.S.
ARE UNDER THE INFLUENCE OF THE ACTIVE NORTHERN STREAM. CLIPPER
CURRENTLY CROSSING THE UPPER MIDWEST HAS WRUNG OUT 1 TO 3 INCHES OF
SNOW FOR NORTHERN SECTIONS OF THE FORECAST AREA. SURFACE LOW OVER
IOWA NEAR FORT DODGE /KFOD/ THIS MORNING WITH THE STRONGEST PRESSURE
FALLS SPANNING EASTERN IOWA. ..DMD..
SHORT TERM...TODAY AND TONIGHT...
MAIN FOCUS THIS MORNING IS WALKING OUT THE SNOWFALL...THEN CLOUDS
FOR THE REMAINDER OF TODAY. RUC FORECASTS SHOW LOW LEVEL
FRONTOGENETIC FORCING ASSOCIATED WITH THE CLIPPER TRACKING RAPIDLY
NORTHEAST ACROSS SOUTHERN WISCONSIN BY 11Z AND RADAR AND SATELLITE
TRENDS SHOW A FAIRLY SHARP BACK EDGE TO THE ACCUMULATING SNOW. THUS
WILL END SNOW ACROSS CWFA BY 12Z. AS FOR THE STRATUS...RUC 800MB RH
FIELD HAS A DECENT HANDLE ON THE CURRENT PROGRESS OF THE CLEARING
LINE AND WILL USE FOR NOWCASTING THE BACK EDGE. THIS TIMING WOULD
SUGGEST CLEARING REACHING THE MISSISSIPPI RIVER BY ABOUT 15Z. ..DMD..
LONG TERM...SUNDAY THROUGH FRIDAY...
A SPLIT FLOW PATTERN WILL REMAIN OVER THE U.S. FOR THE UPCOMING
WEEK. EASTERN PACIFIC S/W ENERGY WILL CONTINUE TO BE SHUNTED NORTH
INTO BRITISH COLUMBIA OR THE PAC NW BY A STUBBORN EASTERN PACIFIC
RIDGE. SOME OF THIS ENERGY GETS PICKED UP IN THE SOUTHERN STREAM FLOW
EAST OF THE RIDGE AXIS...HELPING TO MAINTAIN SOME MID LEVEL
TROFFING OVER THE WESTERN U.S.
THE MAIN CONCERNS FOR THIS PERIOD CONTINUE TO BE IN THE EARLY PART
OF THE WEEK WITH THE SOUTHWESTERN U.S. CUTOFF LOW EJECTING INTO
THE MID MISSISSIPPI VALLEY BY TUESDAY/TUESDAY NIGHT. THE LONG
RANGE MODELS WERE IN REASONABLY GOOD AGREEMENT WITH THIS SYSTEM
WHICH IMPROVES CONFIDENCE THAT THE BULK OF THE PRECIPITATION WILL
STAY TO OUR SOUTH. HOWEVER...A NORTHERN STREAM S/W THAT WILL
INFLUENCE THE TRACK OF THE CUTOFF LOW IS STILL OVER THE PACIFIC
AND IS NOT YET BEING SAMPLED BY THE UPPER AIR NETWORK. THIS COULD
LEAD TO MORE MODEL VARIATIONS WITH THIS SYSTEM ON TODAY/S MODEL
RUNS. ONCE THE S/W REACHES THE WESTERN CONUS THIS EVENING THE
MODELS WILL HAVE MORE DATA TO WORK WITH.
FOR SUNDAY AND SUNDAY NIGHT MILD WEATHER WILL BE OVER THE AREA
WITH SOUTHWESTERLY FLOW IN PLACE AHEAD OF A NORTHERN PLAINS COLD FRONT.
THE NAM/GFS SHOW A LOW LEVEL THERMAL RIDGE OVER THE AREA SUNDAY
AFTERNOON. WITH DRY AIR OVER THE AREA WE SHOULD HAVE MOSTLY SUNNY
SKIES WHICH ALLOW DEEP ENOUGH MIXING TO TAP SOME OF THE WARMER
AIR. THE TEMPERATURE FORECAST FOR SUNDAY AND SUNDAY NIGHT WERE
SKEWED TOWARD THE WARM MET MOS GUIDANCE WHICH SUGGEST MAXT TEMPS
IN THE LOW 50S OVER THE SOUTHWEST AND LOW TO MID 40S NORTHEAST.
INCREASING LOW LEVEL MOISTURE/CLOUDS SUNDAY NIGHT WILL KEEP
TEMPERATURE SOUTH IN THE UPPER 40S. IN THE NORTHWEST THE COLD
FRONT SHOULD BE MOVING IN AFTER MIDNIGHT...DROPPING TEMPERATURES IN
THE MID/UPPER 20S BY MONDAY MORNING.
FOR MONDAY THROUGH TUESDAY NIGHT THE 00Z RUNS ARE IN REASONABLE
AGREEMENT BRINGING THE UPPER LOW OUT ON A MORE SOUTHERLY COURSE.
AS A RESULT HAVE STARTED TO TREND PRECIPITATION CHANCES DOWN ACROSS
THE NORTH AND KEPT POPS IN THE SOUTHERN FOURTH OF THE AREA
LIMITED TO CHANCE CATEGORY. THE EXCEPTION TO THIS WILL BE SOME
LIKELY POPS SOUTH TUESDAY WHEN THE UPPER LOW MOVES INTO MO
SPREADING STRONGLY DIFFLUENT MID LEVEL FLOW SPREADS NORTHEAST
INTO SOUTHERN IA AND CENTRAL IL. THERMAL PROFILES SUGGEST ANY
PRECIPITATION MONDAY WILL BE RAIN. AS THE COLD AIR PUSHES SOUTH
AND DEEPENS MONDAY NIGHT AND TUESDAY THE RAIN SHOULD CHANGE TO
SNOW. WITH MODELS SHOWING THE INITIALLY SHALLOW COLD AIR
UNDERCUTTING WARMER 850MB TEMPS THERE COULD BE SOME SORT OF A MIX
MONDAY AFTERNOON/EVENING ALONG THE NORTHERN EDGE OF THE
PRECIPITATION SHIELD WHICH COULD INCLUDE SLEET AND POSSIBLY SOME
FREEZING RAIN. BY LATE MONDAY NIGHT AND TUESDAY TEMPERATURES
SHOULD BE COLD ENOUGH FOR MAINLY SNOW. THE SYSTEM WILL BE MOVING
EAST OF THE AREA BY LATE TUESDAY NIGHT. BY THIS TIME THERE IS
POTENTIAL FOR SOME MINOR SNOW ACCUMULATIONS ESPECIALLY SOUTH OF
HIGHWAY 34 BETWEEN OTTUMWA AND MACOMB.
FOR THE REST OF THE WEEK HAVE GONE WITH A MAINLY DRY FORECAST
EXPECTING NEAR NORMAL TEMPERATURES. MODELS SHOW THE WESTERN U.S.
TROF REDEVELOPING WITH A S/W EJECTING OUT OF THE TROF BY LATE
WEEK. THE GFS/ECMWF SHOW THE S/W DIGGING WELL INTO MEXICO THEN
EJECTING ON A TRACK THAT WOULD TAKE IT SOUTH OF THE AREA. THE GEM
IS LESS AMPLIFIED AND MOVES THE SYSTEM THROUGH THE MID MISSISSIPPI
VALLEY BY LATE WEEK SUPPORTING SOME PRECIPITATION OVER THE AREA. THE
ONLY POPS THEN WILL BE SOME SLIGHT CHANCE POPS FROM THURSDAY NIGHT
THROUGH FRIDAY TO COVER THE THREAT OF SNOW WITH THE EJECTING WAVE.
DLF..
&&
.DVN WATCHES/WARNINGS/ADVISORIES...
IA...NONE.
IL...NONE.
MO...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS QUAD CITIES IA IL
530 AM CST SAT DEC 17 2011
.AVIATION... /ISSUED 309 AM CST SAT DEC 17 2011/
LINGERING SNOW NORTH AND EAST OF DUBUQUE /KDBQ/ WILL MOVE OUT OF
THE LOCAL AREA BY MID MORNING. OTHERWISE...A WEAK SURFACE LOW
PRESSURE WAVE WILL TRACK ACROSS THE DUBUQUE TRI- STATE REGION...
RESULTING IN VARYING BUT GENERALLY LIGHT SURFACE WINDS. A LARGE
AREA OF MVFR STRATUS CLOUDS WILL ALSO MOVE EAST ACROSS THE AREA
WITH THIS SYSTEM. LOCAL TAF SITES WILL SEE CLEARING OF THIS DECK
BETWEEN 17 AND 21Z TODAY. ..DMD..
&&
.PREV DISCUSSION... /ISSUED 309 AM CST SAT DEC 17 2011/
SYNOPSIS...
ALOFT...THE LONG WAVE PATTERN IS MARKED BY SPLIT FLOW...WITH A
CUT-OFF LOW OVER LOS ANGELES WHILE THE MIDWEST AND NORTHEAST U.S.
ARE UNDER THE INFLUENCE OF THE ACTIVE NORTHERN STREAM. CLIPPER
CURRENTLY CROSSING THE UPPER MIDWEST HAS WRUNG OUT 1 TO 3 INCHES OF
SNOW FOR NORTHERN SECTIONS OF THE FORECAST AREA. SURFACE LOW OVER
IOWA NEAR FORT DODGE /KFOD/ THIS MORNING WITH THE STRONGEST PRESSURE
FALLS SPANNING EASTERN IOWA. ..DMD..
SHORT TERM...TODAY AND TONIGHT...
MAIN FOCUS THIS MORNING IS WALKING OUT THE SNOWFALL...THEN CLOUDS
FOR THE REMAINDER OF TODAY. RUC FORECASTS SHOW LOW LEVEL
FRONTOGENETIC FORCING ASSOCIATED WITH THE CLIPPER TRACKING RAPIDLY
NORTHEAST ACROSS SOUTHERN WISCONSIN BY 11Z AND RADAR AND SATELLITE
TRENDS SHOW A FAIRLY SHARP BACK EDGE TO THE ACCUMULATING SNOW. THUS
WILL END SNOW ACROSS CWFA BY 12Z. AS FOR THE STRATUS...RUC 800MB RH
FIELD HAS A DECENT HANDLE ON THE CURRENT PROGRESS OF THE CLEARING
LINE AND WILL USE FOR NOWCASTING THE BACK EDGE. THIS TIMING WOULD
SUGGEST CLEARING REACHING THE MISSISSIPPI RIVER BY ABOUT 15Z. ..DMD..
LONG TERM...SUNDAY THROUGH FRIDAY...
A SPLIT FLOW PATTERN WILL REMAIN OVER THE U.S. FOR THE UPCOMING
WEEK. EASTERN PACIFIC S/W ENERGY WILL CONTINUE TO BE SHUNTED NORTH
INTO BRITISH COLUMBIA OR THE PAC NW BY A STUBBORN EASTERN PACIFIC
RIDGE. SOME OF THIS ENERGY GETS PICKED UP IN THE SOUTHERN STREAM FLOW
EAST OF THE RIDGE AXIS...HELPING TO MAINTAIN SOME MID LEVEL
TROFFING OVER THE WESTERN U.S.
THE MAIN CONCERNS FOR THIS PERIOD CONTINUE TO BE IN THE EARLY PART
OF THE WEEK WITH THE SOUTHWESTERN U.S. CUTOFF LOW EJECTING INTO
THE MID MISSISSIPPI VALLEY BY TUESDAY/TUESDAY NIGHT. THE LONG
RANGE MODELS WERE IN REASONABLY GOOD AGREEMENT WITH THIS SYSTEM
WHICH IMPROVES CONFIDENCE THAT THE BULK OF THE PRECIPITATION WILL
STAY TO OUR SOUTH. HOWEVER...A NORTHERN STREAM S/W THAT WILL
INFLUENCE THE TRACK OF THE CUTOFF LOW IS STILL OVER THE PACIFIC
AND IS NOT YET BEING SAMPLED BY THE UPPER AIR NETWORK. THIS COULD
LEAD TO MORE MODEL VARIATIONS WITH THIS SYSTEM ON TODAY/S MODEL
RUNS. ONCE THE S/W REACHES THE WESTERN CONUS THIS EVENING THE
MODELS WILL HAVE MORE DATA TO WORK WITH.
FOR SUNDAY AND SUNDAY NIGHT MILD WEATHER WILL BE OVER THE AREA
WITH SOUTHWESTERLY FLOW IN PLACE AHEAD OF A NORTHERN PLAINS COLD FRONT.
THE NAM/GFS SHOW A LOW LEVEL THERMAL RIDGE OVER THE AREA SUNDAY
AFTERNOON. WITH DRY AIR OVER THE AREA WE SHOULD HAVE MOSTLY SUNNY
SKIES WHICH ALLOW DEEP ENOUGH MIXING TO TAP SOME OF THE WARMER
AIR. THE TEMPERATURE FORECAST FOR SUNDAY AND SUNDAY NIGHT WERE
SKEWED TOWARD THE WARM MET MOS GUIDANCE WHICH SUGGEST MAXT TEMPS
IN THE LOW 50S OVER THE SOUTHWEST AND LOW TO MID 40S NORTHEAST.
INCREASING LOW LEVEL MOISTURE/CLOUDS SUNDAY NIGHT WILL KEEP
TEMPERATURE SOUTH IN THE UPPER 40S. IN THE NORTHWEST THE COLD
FRONT SHOULD BE MOVING IN AFTER MIDNIGHT...DROPPING TEMPERATURES IN
THE MID/UPPER 20S BY MONDAY MORNING.
FOR MONDAY THROUGH TUESDAY NIGHT THE 00Z RUNS ARE IN REASONABLE
AGREEMENT BRINGING THE UPPER LOW OUT ON A MORE SOUTHERLY COURSE.
AS A RESULT HAVE STARTED TO TREND PRECIPITATION CHANCES DOWN ACROSS
THE NORTH AND KEPT POPS IN THE SOUTHERN FOURTH OF THE AREA
LIMITED TO CHANCE CATEGORY. THE EXCEPTION TO THIS WILL BE SOME
LIKELY POPS SOUTH TUESDAY WHEN THE UPPER LOW MOVES INTO MO
SPREADING STRONGLY DIFFLUENT MID LEVEL FLOW SPREADS NORTHEAST
INTO SOUTHERN IA AND CENTRAL IL. THERMAL PROFILES SUGGEST ANY
PRECIPITATION MONDAY WILL BE RAIN. AS THE COLD AIR PUSHES SOUTH
AND DEEPENS MONDAY NIGHT AND TUESDAY THE RAIN SHOULD CHANGE TO
SNOW. WITH MODELS SHOWING THE INITIALLY SHALLOW COLD AIR
UNDERCUTTING WARMER 850MB TEMPS THERE COULD BE SOME SORT OF A MIX
MONDAY AFTERNOON/EVENING ALONG THE NORTHERN EDGE OF THE
PRECIPITATION SHIELD WHICH COULD INCLUDE SLEET AND POSSIBLY SOME
FREEZING RAIN. BY LATE MONDAY NIGHT AND TUESDAY TEMPERATURES
SHOULD BE COLD ENOUGH FOR MAINLY SNOW. THE SYSTEM WILL BE MOVING
EAST OF THE AREA BY LATE TUESDAY NIGHT. BY THIS TIME THERE IS
POTENTIAL FOR SOME MINOR SNOW ACCUMULATIONS ESPECIALLY SOUTH OF
HIGHWAY 34 BETWEEN OTTUMWA AND MACOMB.
FOR THE REST OF THE WEEK HAVE GONE WITH A MAINLY DRY FORECAST
EXPECTING NEAR NORMAL TEMPERATURES. MODELS SHOW THE WESTERN U.S.
TROF REDEVELOPING WITH A S/W EJECTING OUT OF THE TROF BY LATE
WEEK. THE GFS/ECMWF SHOW THE S/W DIGGING WELL INTO MEXICO THEN
EJECTING ON A TRACK THAT WOULD TAKE IT SOUTH OF THE AREA. THE GEM
IS LESS AMPLIFIED AND MOVES THE SYSTEM THROUGH THE MID MISSISSIPPI
VALLEY BY LATE WEEK SUPPORTING SOME PRECIPITATION OVER THE AREA. THE
ONLY POPS THEN WILL BE SOME SLIGHT CHANCE POPS FROM THURSDAY NIGHT
THROUGH FRIDAY TO COVER THE THREAT OF SNOW WITH THE EJECTING WAVE.
.DLF..
&&
.DVN WATCHES/WARNINGS/ADVISORIES...
IA...NONE.
IL...NONE.
MO...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS QUAD CITIES IA IL
309 AM CST SAT DEC 17 2011
.SYNOPSIS...
ALOFT...THE LONG WAVE PATTERN IS MARKED BY SPLIT FLOW...WITH A
CUT-OFF LOW OVER LOS ANGELES WHILE THE MIDWEST AND NORTHEAST U.S.
ARE UNDER THE INFLUENCE OF THE ACTIVE NORTHERN STREAM. CLIPPER
CURRENTLY CROSSING THE UPPER MIDWEST HAS WRUNG OUT 1 TO 3 INCHES OF
SNOW FOR NORTHERN SECTIONS OF THE FORECAST AREA. SURFACE LOW OVER
IOWA NEAR FORT DODGE /KFOD/ THIS MORNING WITH THE STRONGEST PRESSURE
FALLS SPANNING EASTERN IOWA. ..DMD..
&&
.SHORT TERM...TODAY AND TONIGHT...
MAIN FOCUS THIS MORNING IS WALKING OUT THE SNOWFALL...THEN CLOUDS
FOR THE REMAINDER OF TODAY. RUC FORECASTS SHOW LOW LEVEL
FRONTOGENETIC FORCING ASSOCIATED WITH THE CLIPPER TRACKING RAPIDLY
NORTHEAST ACROSS SOUTHERN WISCONSIN BY 11Z AND RADAR AND SATELLITE
TRENDS SHOW A FAIRLY SHARP BACK EDGE TO THE ACCUMULATING SNOW. THUS
WILL END SNOW ACROSS CWFA BY 12Z. AS FOR THE STRATUS...RUC 800MB RH
FIELD HAS A DECENT HANDLE ON THE CURRENT PROGRESS OF THE CLEARING
LINE AND WILL USE FOR NOWCASTING THE BACK EDGE. THIS TIMING WOULD
SUGGEST CLEARING REACHING THE MISSISSIPPI RIVER BY ABOUT 15Z. ..DMD..
.LONG TERM...SUNDAY THROUGH FRIDAY...
A SPLIT FLOW PATTERN WILL REMAIN OVER THE U.S. FOR THE UPCOMING
WEEK. EASTERN PACIFIC S/W ENERGY WILL CONTINUE TO BE SHUNTED NORTH
INTO BRITISH COLUMBIA OR THE PAC NW BY A STUBBORN EASTERN PACIFIC
RIDGE. SOME OF THIS ENERGY GETS PICKED UP IN THE SOUTHERN STREAM FLOW
EAST OF THE RIDGE AXIS...HELPING TO MAINTAIN SOME MID LEVEL
TROFFING OVER THE WESTERN U.S.
THE MAIN CONCERNS FOR THIS PERIOD CONTINUE TO BE IN THE EARLY PART
OF THE WEEK WITH THE SOUTHWESTERN U.S. CUTOFF LOW EJECTING INTO
THE MID MISSISSIPPI VALLEY BY TUESDAY/TUESDAY NIGHT. THE LONG
RANGE MODELS WERE IN REASONABLY GOOD AGREEMENT WITH THIS SYSTEM
WHICH IMPROVES CONFIDENCE THAT THE BULK OF THE PRECIPITATION WILL
STAY TO OUR SOUTH. HOWEVER...A NORTHERN STREAM S/W THAT WILL
INFLUENCE THE TRACK OF THE CUTOFF LOW IS STILL OVER THE PACIFIC
AND IS NOT YET BEING SAMPLED BY THE UPPER AIR NETWORK. THIS COULD
LEAD TO MORE MODEL VARIATIONS WITH THIS SYSTEM ON TODAY/S MODEL
RUNS. ONCE THE S/W REACHES THE WESTERN CONUS THIS EVENING THE
MODELS WILL HAVE MORE DATA TO WORK WITH.
FOR SUNDAY AND SUNDAY NIGHT MILD WEATHER WILL BE OVER THE AREA
WITH SOUTHWESTERLY FLOW INPLACE AHEAD OF A NORTHERN PLAINS COLD FRONT.
THE NAM/GFS SHOW A LOW LEVEL THERMAL RIDGE OVER THE AREA SUNDAY
AFTERNOON. WITH DRY AIR OVER THE AREA WE SHOULD HAVE MOSTLY SUNNY
SKIES WHICH ALLOW DEEP ENOUGH MIXING TO TAP SOME OF THE WARMER
AIR. THE TEMPERATURE FORECAST FOR SUNDAY AND SUNDAY NIGHT WERE
SKEWED TOWARD THE WARM MET MOS GUIDANCE WHICH SUGGEST MAXT TEMPS
IN THE LOW 50S OVER THE SOUTHWEST AND LOW TO MID 40S NORTHEAST.
INCREASING LOW LEVEL MOISTURE/CLOUDS SUNDAY NIGHT WILL KEEP
TEMPERATURE SOUTH IN THE UPPER 40S. IN THE NORTHWEST THE COLD
FRONT SHOULD BE MOVING IN AFTER MIDNIGHT...DROPPING TEMPERATURES IN
THE MID/UPPER 20S BY MONDAY MORNING.
FOR MONDAY THROUGH TUESDAY NIGHT THE 00Z RUNS ARE IN REASONABLE
AGREEMENT BRINGING THE UPPER LOW OUT ON A MORE SOUTHERLY COURSE.
AS A RESULT HAVE STARTED TO TREND PRECIPITATION CHANCES DOWN ACROSS
THE NORTH AND KEPT POPS IN THE SOUTHERN FOURTH OF THE AREA
LIMITED TO CHANCE CATEGORY. THE EXCEPTION TO THIS WILL BE SOME
LIKELY POPS SOUTH TUESDAY WHEN THE UPPER LOW MOVES INTO MO
SPREADING STRONGLY DIFFLUENT MID LEVEL FLOW SPREADS NORTHEAST
INTO SOUTHERN IA AND CENTRAL IL. THERMAL PROFILES SUGGEST ANY
PRECIPITATION MONDAY WILL BE RAIN. AS THE COLD AIR PUSHES SOUTH
AND DEEPENS MONDAY NIGHT AND TUESDAY THE RAIN SHOULD CHANGE TO
SNOW. WITH MODELS SHOWING THE INITIALLY SHALLOW COLD AIR
UNDERCUTTING WARMER 850MB TEMPS THERE COULD BE SOME SORT OF A MIX
MONDAY AFTERNOON/EVENING ALONG THE NORTHERN EDGE OF THE
PRECIPITATION SHIELD WHICH COULD INCLUDE SLEET AND POSSIBLY SOME
FREEZING RAIN. BY LATE MONDAY NIGHT AND TUESDAY TEMPERATURES
SHOULD BE COLD ENOUGH FOR MAINLY SNOW. THE SYSTEM WILL BE MOVING
EAST OF THE AREA BY LATE TUESDAY NIGHT. BY THIS TIME THERE IS
POTENTIAL FOR SOME MINOR SNOW ACCUMULATIONS ESPECIALLY SOUTH OF
HIGHWAY 34 BETWEEN OTTUMWA AND MACOMB.
FOR THE REST OF THE WEEK HAVE GONE WITH A MAINLY DRY FORECAST
EXPECTING NEAR NORMAL TEMPERATURES. MODELS SHOW THE WESTERN U.S.
TROF REDEVELOPING WITH A S/W EJECTING OUT OF THE TROF BY LATE
WEEK. THE GFS/ECMWF SHOW THE S/W DIGGING WELL INTO MEXICO THEN
EJECTING ON A TRACK THAT WOULD TAKE IT SOUTH OF THE AREA. THE GEM
IS LESS AMPLIFIED AND MOVES THE SYSTEM THROUGH THE MID MISSISSIPPI
VALLEY BY LATE WEEK SUPPORTING SOME PRECIPITATION OVER THE AREA. THE
ONLY POPS THEN WILL BE SOME SLIGHT CHANCE POPS FROM THURSDAY NIGHT
THROUGH FRIDAY TO COVER THE THREAT OF SNOW WITH THE EJECTING WAVE.
..DLF..
&&
.AVIATION...
LINGERING SNOW NORTH OF HIGHWAY 30 WILL MOVE INTO NORTHEASTERN
ILLINOIS AND SOUTHEASTERN WISCONSIN BY 12Z. OTHERWISE...A WEAK
SURFACE LOW PRESSURE AVE WILL TRACK ACROSS THE DUBUQUE TRI-STATE
REGION...RESULTING IN VARYING BUT GENERALLY LIGHT SURFACE WINDS. A
LARGE AREA OF MVFR STRATUS CLOUDS WILL ALSO MOVE EAST ACROSS THE
AREA WITH THIS SYSTEM. LOCAL TAF SITES WILL SEE CLEARING OF THIS
DECK BETWEEN 14 AND 17Z. ..DMD..
&&
.DVN WATCHES/WARNINGS/ADVISORIES...
IA...NONE.
IL...NONE.
MO...NONE.
&&
$$
DMD/DLF
AREA FORECAST DISCUSSION
NWS GOODLAND KS
925 PM MST FRI DEC 16 2011
.DISCUSSION...
227 PM MST FRI DEC 16 2011
MAIN FORECAST PROBLEM WILL BE STORM FOR THE BEGINNING OF NEXT WEEK
WITH SECONDARY PROBLEMS OF HOW MUCH TO WARM IT UP BEFORE THIS NEXT
UPPER LOW FOLLOWED BY WHAT KIND OF WEATHER THE NEXT COMPLICATED UPPER
TROUGH/S WILL BRING TO THE AREA THE END OF NEXT WEEK. SATELLITE
SHOWING AN AMPLIFIED/AMPLIFYING PATTERN FROM THE PACIFIC INTO NORTH
AMERICA. DUE TO DEEPENING TROUGH OVER THE WESTERN PACIFIC...SOUTHERN
END OF EASTERN PACIFIC TROUGH IS DEEPENING AND CAUSING THE WESTERN
RIDGE TO BUILD. THIS AND HEIGHT FALL ANALYSIS SHOWS UPPER LOW OVER
BAJA SINKING SOUTH AND WEST. THIS IS PART OF SPLIT FLOW/MEAN TROUGH
THAT EXISTS OVER MOST OF THE REST OF THE COUNTRY.
IN REGARDS TO THE JET OVER THE NORTHEAST PACIFIC AND ROUNDING OVER
THE TOP OF THE RIDGE...THE MODELS LOOK UNDERDONE ON SPEEDS. ON THE
SEGMENT THAT EXTENDS FROM MONTANA TO THE NORTHWEST OF THE UPPER LOW
THE MODELS TENDED TO BE SLIGHTLY UNDERDONE AND TOO FAR EAST AND
SOUTH WITH THE SEGMENT. THE NAM WAS DOING THE BEST FOLLOWED BY THE
UKMET AND THE CANADIAN. SAME THING AT MID LEVELS WITH THE NAM DOING
SLIGHTLY BETTER THAN THE CANADIAN AND UKMET. AT THE SURFACE...THE
ECMWF WAS DOING SLIGHTLY BETTER THAN THE NAM. ON THE LOW LEVEL
THERMAL FIELD THE NAM AND GFS WERE DOING SLIGHTLY BETTER THAN THE
REMAINING OUTPUT.
TONIGHT...CURRENT SURFACE OBSERVATIONS SHOW A SURFACE TROUGH MOVING
EAST ACROSS THE TRI-STATE AREA. WINDS HAVE REMAINED LIGHT TO
BREEZY...BUT A FEW GUSTS HAVE APPROACHED 25 MPH AHEAD AND BEHIND THE
TROUGH. RUC UPPER AIR ANALYSIS SHOWS AN UPPER LEVEL TROUGH
FOLLOWING THE SURFACE FEATURE...AND SATELLITE IMAGERY CONTINUES TO
SHOW A FEW MID AND HIGH CLOUDS ON EITHER SIDE OF THE UPPER LEVEL
TROUGH. FURTHER WEST THE CLOSED LOW REMAINS POSITIONED OVER THE
BAJA PENINSULA AND HAS BEEN SLOWLY RETROGRADING TO THE WEST THROUGH
THE DAY.
NORTHWEST WINDS WILL GRADUALLY TURN TO THE WEST DURING THE EVENING...
AS A SURFACE RIDGE OF HIGH PRESSURE MOVES ACROSS THE TRI-STATE AREA
BEHIND THE SURFACE TROUGH. RELATIVE HUMIDITY VALUES WILL BE NEAR 100
PERCENT OVER THE SNOW FIELD FOR THE MCCOOK AND OBERLIN AREA. HOWEVER
THE LIGHT WEST WINDS AND DRY AIR ABOVE THE SURFACE WOULD SUPPORT NO
FOG FORMING. OTHERWISE LOWS WILL BE SIMILAR TO LAST NIGHT.
SATURDAY/SATURDAY NIGHT...AREA REMAINS UNDER SUBSIDENCE AND
INFLUENCE FROM THE MID/UPPER RIDGE. WILL BE DOWNSLOPE WINDS BUT
MOSTLY LIGHT. DID WARM UP TEMPERATURES BUT POTENTIAL IS THERE TO BE
WARMER THAN WHAT I HAVE. DURING THE NIGHT DOWNSLOPE WINDS ARE IN
PLACE AND CLOUDS DO INCREASE A LITTLE.
SUNDAY...MAIN JET IS STILL FAR AWAY FROM THE AREA. DUE TO THE UPPER
LOW STILL BEING VERY FAR AWAY...MID LEVEL RIDGING AND DRYING WILL
BE IN PLACE. BY THIS TIME...WHATEVER SNOW IS HERE NOW SHOULD NOT BE
A FACTOR IN MAXES. MODELS DIFFER ON THE AMOUNT OF WARMUP WITH THE
ECMWF SHOWING THE MOST. THERE IS WEAK DOWNSLOPING OF THE WINDS WITH
THE MODELS SHOWING LITTLE IF ANY MIXING. ALSO BECAUSE OF THE
MID/UPPER LEVEL RIDGING IN PLACE...IT LOOKS LIKE THERE WILL BE A LOT
OF SUNSHINE. SO IT LOOKS LIKE MODELS ARE UNDERDOING THE WARMING AT
THIS TIME. RAISED MAXES BUT TEMPERED IT SOMEWHAT BASED ON
COLLABORATION AND THRESHOLDS. HOWEVER...THE POTENTIAL FOR BEING
MUCH WARMER THAN WHAT IS CURRENTLY IN THERE IS PRETTY HIGH. IF THE
MIXING GETS CLOSER TO 700 MB...TEMPERATURES COULD SORE INTO THE 60S
BUT I DEFINITELY DID NOT GO THAT FAR.
SUNDAY NIGHT/MONDAY...WEAKER LEFT FRONT QUADRANT OF THE SOUTHERN JET
LOOKS TO START AFFECT THE SOUTHEAST PORTION OF THE AREA LATE IN THE
NIGHT. OF NOTE HIGHER JET SPEEDS ARE STILL BEHIND INCOMING SYSTEM
AS OF 12Z MONDAY. MOST OF THE DETERMINISTIC AND ENSEMBLE DATA SHOW
THE NEXT SYSTEM COMING FURTHER SOUTH AND SLOWER WITH STILL SOMEWHAT
OF A SPREAD. THE NAM AND GEFS MEAN ARE THE FASTEST AND FURTHEST
NORTH WITH THE CANADIAN AND ECMWF FURTHEST SOUTH. IT IS STARTING TO
LOOK LIKE FURTHER SOUTH IS APPEARING MORE LIKELY. THAT SAID WITH
LITTLE IF ANY LIFT AND SOUNDINGS SHOWING AIR MASS STILL DRY...THE
DRY FORECAST FOR SUNDAY NIGHT STILL LOOKS GOOD.
LEFT FRONT QUADRANT OF THE JET AFFECTS MAINLY SOUTHEAST HALF OF THE
AREA EARLY IN THE DAY. MOST OF THE FORCING STILL LOOKS TO BE OVER
TH SOUTHERN PORTION OF THE AREA. IF NAM/GEFS RIGHT...PRECIPITATION
CHANCE WILL BE GREATER. IF ECMWF AND ESPECIALLY THE CANADIAN IS
RIGHT...PRECIPITATION WILL BE LOWER. SINCE THERE IS STILL A LOT OF
MODEL SPREAD AND CURRENT MODEL DATA SUPPORTS THE ONGOING FORECAST...
DID NOT CHANGE MONDAYS PRECIPITATION FORECAST. IT WILL DEFINITELY
WILL BE WINDY AND COLDER ON MONDAY. IF CURRENT TRENDS CONTINUE IT IS
POSSIBLE THAT MAXES WILL NEED TO BE LOWERED MORE.
MONDAY NIGHT THROUGH FRIDAY...SPREAD ON THE DETERMINISTIC AND
ENSEMBLE OUTPUT EARLY ON THROUGH TUESDAY IS PRETTY LARGE. THINKING
THAT THE SYSTEM IS LOOKING TO BE FURTHER SOUTH...PRECIPITATION
SHOULD BE DONE OR MOSTLY DONE BY 12Z TUESDAY. MODERATION OF
TEMPERATURES THEN OCCUR AS THE WESTERN TROUGH RELOADS AND MODELS TRY
TO DECIDE WHAT TO DO WITH THE NEXT SYSTEM. SPREAD IN DETERMINISTIC
AND ENSEMBLE OUTPUT CONTINUES WITH THIS NEXT SET OF STORM SYSTEMS AS
WELL.
ON THURSDAY ALL THE MODELS DO BRING A MID LEVEL TROUGH THROUGH
BUT DIFFER ON THE STRENGTH AND SPEED. IF ECMWF WERE TO VERIFY THEN
PRECIPITATION MAY NEED TO BE EXPANDED FROM WHERE IT IS AT NOW. MODELS
SHOW A FRONT MOVE THROUGH LATE WEDNESDAY NIGHT INTO THURSDAY BUT
DIFFER ON TIME. DUE TO ITS HANDLING OF THE SYSTEM AT MID LEVELS...
THE ECMWF IS MORE AGGRESSIVE WITH THE COOLING...AND LOOKS LIKE IT
IS THE BEST SOLUTION...TEMPERATURES WILL BE COOLED MORE FROM THEY
ARE AT NOW. FRIDAY LOOKS DRY AT THIS TIME BUT WITH MODEL SPREAD
THAT COULD CHANGE. COLDER WORKS ITS WAY INTO THE AREA...COLD MAXES
IN GRIDS LOOK GOOD.
THANKS TO ALL THAT COLLABORATED.
BULLER
&&
.AVIATION...
925 PM MST FRI DEC 16 2011
FOR THE 06Z TAFS...VFR CONDITIONS WITH A GENERAL LIGHT WESTERLY WIND
WILL PREVAIL THROUGH THE VALID PERIOD AS UPPER LEVEL HIGH PRESSURE
CONTINUES TO BUILD INTO THE REGION WITH SURFACE HIGH PRESSURE CENTERED
OVER THE TX/OK PANHANDLE REGION.
050
&&
.GLD WATCHES/WARNINGS/ADVISORIES...
KS...NONE.
NE...NONE.
CO...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
101 PM EST SAT DEC 17 2011
UPDATED AVIATION DISCUSSION FOR 18Z TAFS
.SYNOPSIS...
WATER VAPOR IMAGERY AND RUC ANALYSIS CONTINUE TO SHOW RIDGING INTO
WRN CANADA. DOWNSTREAM...A TROF EXTENDS S INTO THE ERN CONUS FROM A
POLAR VORTEX CENTERED JUST N OF HUDSON BAY. IN THE NW FLOW DIRECTED
INTO THE GREAT LAKES...A VIGOROUS LOOKING SHORTWAVE IS DIVING SE
THRU SRN MANITOBA. CANADIAN RADARS SHOW A SMALL AREA OF -SN
DEVELOPING SE TOWARD NRN MN IN ASSOCIATION WITH THE WAVE. CLOSER TO
HOME...DESPITE 850MB TEMPS AROUND -15C OVER LAKE SUPERIOR...LES TO
THE E OF KMQT HAS DIMINISHED TO JUST SOME FLURRIES. OVER THE W...
THERE`S VERY LITTLE OR NO CLOUDS OFF THE LAKE...SURPRISING GIVEN THE
OVERWATER INSTABILITY. PERIOD OF MOSTLY CLEAR SKIES HAS ALLOWED
TEMPS TO FALL TO NEAR OR JUST BLO 0F AT MANY LOCATIONS OVER WRN
UPPER MI...INCLUDING THE KEWEENAW.
&&
.DISCUSSION...
WEATHER THRU THIS FCST PERIOD WILL BE DOMINATED BY A MEAN RIDGE OF
VARYING AMPLITUDE EXTENDING INTO WRN CANADA AND A DOWNSTREAM POLAR
VORTEX IN THE VCNTY OF NRN HUDSON BAY/BAFFIN ISLAND. IN GENERAL...
BLO NORMAL HEIGHTS WILL EXIST ACROSS NRN CANADA. END RESULT WILL BE
A SERIES OF MOISTURE STARVED NRN STREAM SHORTWAVES PRODUCING LITTLE
PCPN OUTSIDE OF AREAS THAT MIGHT SEE SOME LIGHT LAKE EFFECT/LAKE
ENHANCED SNOW WITH EACH PASSING WAVE. FLOW ALSO LOOKS TO REMAIN
SPLIT WITH SRN STREAM WAVES AND ASSOCIATED PCPN PASSING S OF UPPER
MI. OVERALL...IT WILL NOT BE VERY WINTRY ACROSS THE UPPER LAKES
HEADING TOWARD LATE DEC AS NORTHERLY POSITION OF POLAR VORTEX AND
BLO NORMAL HEIGHTS ACROSS NRN CANADA HOLD ARCTIC AIR N OF THE AREA.
ONLY BRIEF INTRUSIONS OF COLDER AIR WILL OCCUR OVER THE NEXT 7
DAYS...AND TEMPS OVERALL WILL END UP ABOVE NORMAL. LATEST CPC
8-14DAY OUTLOOK CARRIES ENHANCED ODDS OF ABOVE NORMAL TEMPS OVER
UPPER MI THRU THE END OF DEC.
FOR TODAY...VIGOROUS SHORTWAVE WILL DROP THRU THE UPPER GREAT
LAKES...BUT IT WILL BE WEAKENING AS IT DOES SO. THIS IS VERY EVIDENT
IN DEEP LAYER QVECTORS WHICH SUGGEST HEALTHY DYNAMICS NW OF THE AREA
EARLY THIS MORNING RAPIDLY WEAKENING AS SHORTWAVE MOVES ACROSS THE
UPPER LAKES DURING THE DAY. ALTHOUGH FORCING WILL BE WEAKENING...
STEEP MIDLEVEL LAPSE RATES UPWARDS OF 7.5C/KM MAY HELP TO MAINTAIN
SOME AREAS OF -SN SPREADING INTO THE AREA. ANY SYNOPTIC SNOW
ACCUMULATION WILL BE UNDER AN INCH. 850MB TEMPS AROUND -10C SHOULD
SUPPORT SOME LAKE ENHANCEMENT OVER WRN LAKE SUPERIOR INTO WRN UPPER
MI AS WINDS SHIFT FROM SW TO NW. SHOULDN`T BE A BIG DEAL GIVEN SHORT
WINDOW OF ENHANCEMENT (PROBABLY NOTHING MORE THAN AN INCH OR TWO OF
ACCUMULATION OVER THE NW THIS AFTN INTO EARLY EVENING). BRIEF
ENHANCEMENT WILL SHIFT TO AREAS E OF KMQT THIS EVENING AS WINDS
SHIFT NW (LIMITED ACCUMULATION THERE AS WELL). THERE IS ALSO THE
POTENTIAL FOR SOME LAKE ENHANCEMENT OFF NRN LAKE MICHIGAN INTO THE
FAR ERN FCST AREA THIS AFTN/EARLY EVENING IN THE SW FLOW AHEAD OF
THE SHORTWAVE. SOME GUIDANCE SUGGESTS WINDS WILL BACK ENOUGH FOR
LAKE ENHANCEMENT TO CLIP SCHOOLCRAFT/LUCE COUNTIES. UTILIZED HIGHER
POPS IN THAT AREA...BUT KEPT ACCUMULATIONS ONLY AROUND 1 INCH GIVEN
UNCERTAINTY IN HOW MUCH LOW-LEVEL WINDS WILL BACK.
A LITTLE LIGHT -SN MAY LINGER THIS EVENING OVER THE E IN ASSOCIATION
WITH DEPARTING SHORTWAVE. OTHERWISE...IF THERE IS ANY SCT LIGHT NW
FLOW LES (850MB TEMPS AROUND -12C) BEHIND SYSTEM...IT WILL RAPIDLY
END TONIGHT FROM W TO E UNDER SUBSTANTIAL HEIGHT RISES (500MB
HEIGHTS RISE MORE THAN 120M). ALSO...AIR MASS QUICKLY DRIES...
INVERSION CRASHES TO 3KFT...WINDS BACK AND WAA GETS UNDERWAY.
ON SUN...NEXT SHORTWAVE WILL BE DROPPING SE TOWARD NRN ONTARIO. ALL
GUIDANCE SHOW ASSOCIATED SFC LOW PASSING WELL N OF HERE ACROSS NRN
ONTARIO SUN NIGHT. AHEAD OF WAVE...IMPRESSIVE WAA WILL SEND 850MB
TEMPS ABOVE 0C ACROSS THE FCST AREA SUN. GFS IS MOST AGGRESSIVE WITH
THE WARMING AS IT HAS 850MB TEMPS RANGING FROM 2C E TO 7C W BY SUN
EVENING. ISENTROPIC ASCENT IS STRONG SUN WITH 40KT WINDS ORIENTED
PERPENDICULAR TO TIGHTLY SPACED ISOBARS PER 290K SFC. HOWEVER...
WITH DRY AIR HOLDING AT THE LOW-LEVELS PER FCST SOUNDINGS...PCPN
DEVELOPING ALOFT WILL PROBABLY NOT REACH THE SFC. FOR NOW...WILL
CONTINUE TO CARRY A DRY FCST SUN/SUN NIGHT WITH ANY PCPN PASSING N
OF UPPER MI. IF ANYTHING...WILL NEED TO WATCH FOR SOME LIGHT PCPN
CLIPPING THE KEWEENAW AND THE NE FCST AREA. SHALLOW MOISTURE
DROPPING INTO THE AREA BEHIND COLD FRONT ALONG WITH 850MB TEMPS
FALLING PERHAPS TO AROUND -12C MAY SUPPORT SOME LIGHT LES/FLURRIES
OFF LAKE SUPERIOR LATE SUN NIGHT INTO MON EVENING.
AS PREVIOUSLY MENTIONED...PATTERN NEXT WEEK WILL FEATURE LIMITED
PCPN CHANCES WITH TEMPS AVERAGING ABOVE NORMAL. AT THIS TIME...IT
APPEARS SHORTWAVES WILL PASS ACROSS THE AREA AT SOME POINT LATER
TUE/EARLY WED AND THEN THU. OF THE 2 SHORTWAVES...THE SECOND SHOULD
PROVIDE A BETTER CHC OF PCPN.
&&
.AVIATION /FOR THE 18Z TAF ISSUANCE/...
THERE WILL BE A COUPLE DIFFERENT PERIODS OF INTEREST FOR THIS TAF
ISSUANCE...INITIALLY WITH A DISTURBANCE SWEEPING IN FROM THE
NW...AND TOWARDS THE END OF THE PERIOD WITH INCREASING SOUTHERLY
WINDS AHEAD OF THE NEXT SFC LOW NEARING FROM SOUTHERN MANITOBA. VIS
WAS TEMPORARILY REDUCED TO LESS THAN 2SM AT IWD...ASSOCIATED WITH A
BAND OF LOWER CLOUDS AND -SHSN MEASURING 80 MILES ACROSS NEAR IWD.
AS A RESULT...EXPECT RESTRICTIONS /FUEL ALT CEIGS/ AT ALL 3 SITES
FROM TIME TO TIME THROUGH 02 TO 04Z...AND POSSIBLY A BIT LONGER AT
CMX WHICH WILL BE CLOSER TO THE EXITING DISTURBANCE AND HAVE
FAVORABLE WIND COMPONENT OFF THE LAKE. VFR CEIGS AND VIS WILL THEN
BE THE RULE...THROUGH SUNDAY AFTERNOON...WITH INCREASING SOUTHERLY
WINDS GUSTING 22 TO 30KTS /STRONGEST AT SAW AND TO A LESSER EXTENT
IWD/.
&&
.MARINE /FOR THE 4AM LAKE SUPERIOR FORECAST ISSUANCE/...
A SERIES OF LOW PRESSURE SYSTEMS MOVING THROUGH SOUTHERN CANADA WILL
PUSH SEVERAL SFC TROUGHS ACROSS LAKE SUPERIOR THROUGH THE FORECAST
PERIOD. FIRST TROUGH APPROACHES TODAY...WHICH WILL INCREASE WINDS TO
30KTS OUT OF THE SW TODAY...ALTHOUGH THERE COULD BE A FEW ISOLATED
GALE FORCE GUSTS OVER THE WRN LK. WINDS WILL DIMINISH OVERNIGHT
BEFORE INCREASING AGAIN SUNDAY AFTERNOON AHEAD OF THE NEXT TROUGH.
STRONG INVERSION JUST ABOVE THE SFC WILL LIKELY KEEP SUSTAINED WINDS
IN THE 20-30KT RANGE SUN AFTN AND NIGHT. DEPENDING ON THE STRENGTH
OF THE INVERSION...THERE MAY BE SOME GALE FORCE GUSTS TO 35KTS...DUE
TO WSW WINDS OF 40-50KTS 2-3KFT ABOVE THE LAKE. CONSIDERED ISSUING A
GALE WATCH...BUT WASN/T CONFIDENT ENOUGH ON GALES OCCURRING WITH THE
SW WINDS. THINK THE BEST CHANCE WILL BE AS WINDS TURN TO THE W IN
THE EVENING AND HAVE MENTIONED GALES IN THE TEXT. LIGHTER WINDS ARE
EXPECTED MON AFTN INTO MON NIGHT...BEFORE THE NEXT TROUGH APPROACHES
ON TUESDAY AND PRODUCES GUSTS TO 30KTS. THERE MAY BE A FEW GALE
FORCE GUSTS TO 35KTS OVER CENTRAL LAKE SUPERIOR TUESDAY AFTERNOON.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
NONE.
LAKE MICHIGAN...
NONE.
&&
$$
SYNOPSIS...ROLFSON
DISCUSSION...ROLFSON
AVIATION...KF
MARINE...SRF
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
630 AM EST SAT DEC 17 2011
UPDATED AVIATION DISCUSSION FOR 12Z TAFS
.SYNOPSIS...
WATER VAPOR IMAGERY AND RUC ANALYSIS CONTINUE TO SHOW RIDGING INTO
WRN CANADA. DOWNSTREAM...A TROF EXTENDS S INTO THE ERN CONUS FROM A
POLAR VORTEX CENTERED JUST N OF HUDSON BAY. IN THE NW FLOW DIRECTED
INTO THE GREAT LAKES...A VIGOROUS LOOKING SHORTWAVE IS DIVING SE
THRU SRN MANITOBA. CANADIAN RADARS SHOW A SMALL AREA OF -SN
DEVELOPING SE TOWARD NRN MN IN ASSOCIATION WITH THE WAVE. CLOSER TO
HOME...DESPITE 850MB TEMPS AROUND -15C OVER LAKE SUPERIOR...LES TO
THE E OF KMQT HAS DIMINISHED TO JUST SOME FLURRIES. OVER THE W...
THERE`S VERY LITTLE OR NO CLOUDS OFF THE LAKE...SURPRISING GIVEN THE
OVERWATER INSTABILITY. PERIOD OF MOSTLY CLEAR SKIES HAS ALLOWED
TEMPS TO FALL TO NEAR OR JUST BLO 0F AT MANY LOCATIONS OVER WRN
UPPER MI...INCLUDING THE KEWEENAW.
&&
.DISCUSSION...
WEATHER THRU THIS FCST PERIOD WILL BE DOMINATED BY A MEAN RIDGE OF
VARYING AMPLITUDE EXTENDING INTO WRN CANADA AND A DOWNSTREAM POLAR
VORTEX IN THE VCNTY OF NRN HUDSON BAY/BAFFIN ISLAND. IN GENERAL...
BLO NORMAL HEIGHTS WILL EXIST ACROSS NRN CANADA. END RESULT WILL BE
A SERIES OF MOISTURE STARVED NRN STREAM SHORTWAVES PRODUCING LITTLE
PCPN OUTSIDE OF AREAS THAT MIGHT SEE SOME LIGHT LAKE EFFECT/LAKE
ENHANCED SNOW WITH EACH PASSING WAVE. FLOW ALSO LOOKS TO REMAIN
SPLIT WITH SRN STREAM WAVES AND ASSOCIATED PCPN PASSING S OF UPPER
MI. OVERALL...IT WILL NOT BE VERY WINTRY ACROSS THE UPPER LAKES
HEADING TOWARD LATE DEC AS NORTHERLY POSITION OF POLAR VORTEX AND
BLO NORMAL HEIGHTS ACROSS NRN CANADA HOLD ARCTIC AIR N OF THE AREA.
ONLY BRIEF INTRUSIONS OF COLDER AIR WILL OCCUR OVER THE NEXT 7
DAYS...AND TEMPS OVERALL WILL END UP ABOVE NORMAL. LATEST CPC
8-14DAY OUTLOOK CARRIES ENHANCED ODDS OF ABOVE NORMAL TEMPS OVER
UPPER MI THRU THE END OF DEC.
FOR TODAY...VIGOROUS SHORTWAVE WILL DROP THRU THE UPPER GREAT
LAKES...BUT IT WILL BE WEAKENING AS IT DOES SO. THIS IS VERY EVIDENT
IN DEEP LAYER QVECTORS WHICH SUGGEST HEALTHY DYNAMICS NW OF THE AREA
EARLY THIS MORNING RAPIDLY WEAKENING AS SHORTWAVE MOVES ACROSS THE
UPPER LAKES DURING THE DAY. ALTHOUGH FORCING WILL BE WEAKENING...
STEEP MIDLEVEL LAPSE RATES UPWARDS OF 7.5C/KM MAY HELP TO MAINTAIN
SOME AREAS OF -SN SPREADING INTO THE AREA. ANY SYNOPTIC SNOW
ACCUMULATION WILL BE UNDER AN INCH. 850MB TEMPS AROUND -10C SHOULD
SUPPORT SOME LAKE ENHANCEMENT OVER WRN LAKE SUPERIOR INTO WRN UPPER
MI AS WINDS SHIFT FROM SW TO NW. SHOULDN`T BE A BIG DEAL GIVEN SHORT
WINDOW OF ENHANCEMENT (PROBABLY NOTHING MORE THAN AN INCH OR TWO OF
ACCUMULATION OVER THE NW THIS AFTN INTO EARLY EVENING). BRIEF
ENHANCEMENT WILL SHIFT TO AREAS E OF KMQT THIS EVENING AS WINDS
SHIFT NW (LIMITED ACCUMULATION THERE AS WELL). THERE IS ALSO THE
POTENTIAL FOR SOME LAKE ENHANCEMENT OFF NRN LAKE MICHIGAN INTO THE
FAR ERN FCST AREA THIS AFTN/EARLY EVENING IN THE SW FLOW AHEAD OF
THE SHORTWAVE. SOME GUIDANCE SUGGESTS WINDS WILL BACK ENOUGH FOR
LAKE ENHANCEMENT TO CLIP SCHOOLCRAFT/LUCE COUNTIES. UTILIZED HIGHER
POPS IN THAT AREA...BUT KEPT ACCUMULATIONS ONLY AROUND 1 INCH GIVEN
UNCERTAINTY IN HOW MUCH LOW-LEVEL WINDS WILL BACK.
A LITTLE LIGHT -SN MAY LINGER THIS EVENING OVER THE E IN ASSOCIATION
WITH DEPARTING SHORTWAVE. OTHERWISE...IF THERE IS ANY SCT LIGHT NW
FLOW LES (850MB TEMPS AROUND -12C) BEHIND SYSTEM...IT WILL RAPIDLY
END TONIGHT FROM W TO E UNDER SUBSTANTIAL HEIGHT RISES (500MB
HEIGHTS RISE MORE THAN 120M). ALSO...AIR MASS QUICKLY DRIES...
INVERSION CRASHES TO 3KFT...WINDS BACK AND WAA GETS UNDERWAY.
ON SUN...NEXT SHORTWAVE WILL BE DROPPING SE TOWARD NRN ONTARIO. ALL
GUIDANCE SHOW ASSOCIATED SFC LOW PASSING WELL N OF HERE ACROSS NRN
ONTARIO SUN NIGHT. AHEAD OF WAVE...IMPRESSIVE WAA WILL SEND 850MB
TEMPS ABOVE 0C ACROSS THE FCST AREA SUN. GFS IS MOST AGGRESSIVE WITH
THE WARMING AS IT HAS 850MB TEMPS RANGING FROM 2C E TO 7C W BY SUN
EVENING. ISENTROPIC ASCENT IS STRONG SUN WITH 40KT WINDS ORIENTED
PERPENDICULAR TO TIGHTLY SPACED ISOBARS PER 290K SFC. HOWEVER...
WITH DRY AIR HOLDING AT THE LOW-LEVELS PER FCST SOUNDINGS...PCPN
DEVELOPING ALOFT WILL PROBABLY NOT REACH THE SFC. FOR NOW...WILL
CONTINUE TO CARRY A DRY FCST SUN/SUN NIGHT WITH ANY PCPN PASSING N
OF UPPER MI. IF ANYTHING...WILL NEED TO WATCH FOR SOME LIGHT PCPN
CLIPPING THE KEWEENAW AND THE NE FCST AREA. SHALLOW MOISTURE
DROPPING INTO THE AREA BEHIND COLD FRONT ALONG WITH 850MB TEMPS
FALLING PERHAPS TO AROUND -12C MAY SUPPORT SOME LIGHT LES/FLURRIES
OFF LAKE SUPERIOR LATE SUN NIGHT INTO MON EVENING.
AS PREVIOUSLY MENTIONED...PATTERN NEXT WEEK WILL FEATURE LIMITED
PCPN CHANCES WITH TEMPS AVERAGING ABOVE NORMAL. AT THIS TIME...IT
APPEARS SHORTWAVES WILL PASS ACROSS THE AREA AT SOME POINT LATER
TUE/EARLY WED AND THEN THU. OF THE 2 SHORTWAVES...THE SECOND SHOULD
PROVIDE A BETTER CHC OF PCPN.
&&
.AVIATION /FOR THE 12Z TAF ISSUANCE/...
A DISTURBANCE DROPPING SE OUT OF CANADA TODAY WILL LEAD TO LOWERING
CIGS LATE THIS MORNING AND -SHSN THIS AFTN. EXPECT FUEL ALTERNATE
CIGS FOR MUCH OF THE LATE MORNING INTO THE EVENING WITH THE PASSAGE
OF THE DISTURBANCE AND ASSOCIATED -SHSN. HAD HIGHEST CONF OF IFR
VSBYS AT KCMX...BUT WOULDN/T BE SURPRISED TO SEE A SHORT PERIOD OF
IFR VSBYS AT KIWD/KSAW. OTHER THAN SOME LINGERING LK ENHANCED CLOUDS
AT KCMX...EXPECT A TRANSITION TO VFR COND DURING THE EVENING.
&&
.MARINE /FOR THE 4AM LAKE SUPERIOR FORECAST ISSUANCE/...
A SERIES OF LOW PRESSURE SYSTEMS MOVING THROUGH SOUTHERN CANADA WILL
PUSH SEVERAL SFC TROUGHS ACROSS LAKE SUPERIOR THROUGH THE FORECAST
PERIOD. FIRST TROUGH APPROACHES TODAY...WHICH WILL INCREASE WINDS TO
30KTS OUT OF THE SW TODAY...ALTHOUGH THERE COULD BE A FEW ISOLATED
GALE FORCE GUSTS OVER THE WRN LK. WINDS WILL DIMINISH OVERNIGHT
BEFORE INCREASING AGAIN SUNDAY AFTERNOON AHEAD OF THE NEXT TROUGH.
STRONG INVERSION JUST ABOVE THE SFC WILL LIKELY KEEP SUSTAINED WINDS
IN THE 20-30KT RANGE SUN AFTN AND NIGHT. DEPENDING ON THE STRENGTH
OF THE INVERSION...THERE MAY BE SOME GALE FORCE GUSTS TO 35KTS...DUE
TO WSW WINDS OF 40-50KTS 2-3KFT ABOVE THE LAKE. CONSIDERED ISSUING A
GALE WATCH...BUT WASN/T CONFIDENT ENOUGH ON GALES OCCURRING WITH THE
SW WINDS. THINK THE BEST CHANCE WILL BE AS WINDS TURN TO THE W IN
THE EVENING AND HAVE MENTIONED GALES IN THE TEXT. LIGHTER WINDS ARE
EXPECTED MON AFTN INTO MON NIGHT...BEFORE THE NEXT TROUGH APPROACHES
ON TUESDAY AND PRODUCES GUSTS TO 30KTS. THERE MAY BE A FEW GALE
FORCE GUSTS TO 35KTS OVER CENTRAL LAKE SUPERIOR TUESDAY AFTERNOON.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
NONE.
LAKE MICHIGAN...
NONE.
&&
$$
SYNOPSIS...ROLFSON
DISCUSSION...ROLFSON
AVIATION...SRF
MARINE...SRF
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
532 AM EST SAT DEC 17 2011
.SYNOPSIS...
WATER VAPOR IMAGERY AND RUC ANALYSIS CONTINUE TO SHOW RIDGING INTO
WRN CANADA. DOWNSTREAM...A TROF EXTENDS S INTO THE ERN CONUS FROM A
POLAR VORTEX CENTERED JUST N OF HUDSON BAY. IN THE NW FLOW DIRECTED
INTO THE GREAT LAKES...A VIGOROUS LOOKING SHORTWAVE IS DIVING SE
THRU SRN MANITOBA. CANADIAN RADARS SHOW A SMALL AREA OF -SN
DEVELOPING SE TOWARD NRN MN IN ASSOCIATION WITH THE WAVE. CLOSER TO
HOME...DESPITE 850MB TEMPS AROUND -15C OVER LAKE SUPERIOR...LES TO
THE E OF KMQT HAS DIMINISHED TO JUST SOME FLURRIES. OVER THE W...
THERE`S VERY LITTLE OR NO CLOUDS OFF THE LAKE...SURPRISING GIVEN THE
OVERWATER INSTABILITY. PERIOD OF MOSTLY CLEAR SKIES HAS ALLOWED
TEMPS TO FALL TO NEAR OR JUST BLO 0F AT MANY LOCATIONS OVER WRN
UPPER MI...INCLUDING THE KEWEENAW.
&&
.DISCUSSION...
WEATHER THRU THIS FCST PERIOD WILL BE DOMINATED BY A MEAN RIDGE OF
VARYING AMPLITUDE EXTENDING INTO WRN CANADA AND A DOWNSTREAM POLAR
VORTEX IN THE VCNTY OF NRN HUDSON BAY/BAFFIN ISLAND. IN GENERAL...
BLO NORMAL HEIGHTS WILL EXIST ACROSS NRN CANADA. END RESULT WILL BE
A SERIES OF MOISTURE STARVED NRN STREAM SHORTWAVES PRODUCING LITTLE
PCPN OUTSIDE OF AREAS THAT MIGHT SEE SOME LIGHT LAKE EFFECT/LAKE
ENHANCED SNOW WITH EACH PASSING WAVE. FLOW ALSO LOOKS TO REMAIN
SPLIT WITH SRN STREAM WAVES AND ASSOCIATED PCPN PASSING S OF UPPER
MI. OVERALL...IT WILL NOT BE VERY WINTRY ACROSS THE UPPER LAKES
HEADING TOWARD LATE DEC AS NORTHERLY POSITION OF POLAR VORTEX AND
BLO NORMAL HEIGHTS ACROSS NRN CANADA HOLD ARCTIC AIR N OF THE AREA.
ONLY BRIEF INTRUSIONS OF COLDER AIR WILL OCCUR OVER THE NEXT 7
DAYS...AND TEMPS OVERALL WILL END UP ABOVE NORMAL. LATEST CPC
8-14DAY OUTLOOK CARRIES ENHANCED ODDS OF ABOVE NORMAL TEMPS OVER
UPPER MI THRU THE END OF DEC.
FOR TODAY...VIGOROUS SHORTWAVE WILL DROP THRU THE UPPER GREAT
LAKES...BUT IT WILL BE WEAKENING AS IT DOES SO. THIS IS VERY EVIDENT
IN DEEP LAYER QVECTORS WHICH SUGGEST HEALTHY DYNAMICS NW OF THE AREA
EARLY THIS MORNING RAPIDLY WEAKENING AS SHORTWAVE MOVES ACROSS THE
UPPER LAKES DURING THE DAY. ALTHOUGH FORCING WILL BE WEAKENING...
STEEP MIDLEVEL LAPSE RATES UPWARDS OF 7.5C/KM MAY HELP TO MAINTAIN
SOME AREAS OF -SN SPREADING INTO THE AREA. ANY SYNOPTIC SNOW
ACCUMULATION WILL BE UNDER AN INCH. 850MB TEMPS AROUND -10C SHOULD
SUPPORT SOME LAKE ENHANCEMENT OVER WRN LAKE SUPERIOR INTO WRN UPPER
MI AS WINDS SHIFT FROM SW TO NW. SHOULDN`T BE A BIG DEAL GIVEN SHORT
WINDOW OF ENHANCEMENT (PROBABLY NOTHING MORE THAN AN INCH OR TWO OF
ACCUMULATION OVER THE NW THIS AFTN INTO EARLY EVENING). BRIEF
ENHANCEMENT WILL SHIFT TO AREAS E OF KMQT THIS EVENING AS WINDS
SHIFT NW (LIMITED ACCUMULATION THERE AS WELL). THERE IS ALSO THE
POTENTIAL FOR SOME LAKE ENHANCEMENT OFF NRN LAKE MICHIGAN INTO THE
FAR ERN FCST AREA THIS AFTN/EARLY EVENING IN THE SW FLOW AHEAD OF
THE SHORTWAVE. SOME GUIDANCE SUGGESTS WINDS WILL BACK ENOUGH FOR
LAKE ENHANCEMENT TO CLIP SCHOOLCRAFT/LUCE COUNTIES. UTILIZED HIGHER
POPS IN THAT AREA...BUT KEPT ACCUMULATIONS ONLY AROUND 1 INCH GIVEN
UNCERTAINTY IN HOW MUCH LOW-LEVEL WINDS WILL BACK.
A LITTLE LIGHT -SN MAY LINGER THIS EVENING OVER THE E IN ASSOCIATION
WITH DEPARTING SHORTWAVE. OTHERWISE...IF THERE IS ANY SCT LIGHT NW
FLOW LES (850MB TEMPS AROUND -12C) BEHIND SYSTEM...IT WILL RAPIDLY
END TONIGHT FROM W TO E UNDER SUBSTANTIAL HEIGHT RISES (500MB
HEIGHTS RISE MORE THAN 120M). ALSO...AIR MASS QUICKLY DRIES...
INVERSION CRASHES TO 3KFT...WINDS BACK AND WAA GETS UNDERWAY.
ON SUN...NEXT SHORTWAVE WILL BE DROPPING SE TOWARD NRN ONTARIO. ALL
GUIDANCE SHOW ASSOCIATED SFC LOW PASSING WELL N OF HERE ACROSS NRN
ONTARIO SUN NIGHT. AHEAD OF WAVE...IMPRESSIVE WAA WILL SEND 850MB
TEMPS ABOVE 0C ACROSS THE FCST AREA SUN. GFS IS MOST AGGRESSIVE WITH
THE WARMING AS IT HAS 850MB TEMPS RANGING FROM 2C E TO 7C W BY SUN
EVENING. ISENTROPIC ASCENT IS STRONG SUN WITH 40KT WINDS ORIENTED
PERPENDICULAR TO TIGHTLY SPACED ISOBARS PER 290K SFC. HOWEVER...
WITH DRY AIR HOLDING AT THE LOW-LEVELS PER FCST SOUNDINGS...PCPN
DEVELOPING ALOFT WILL PROBABLY NOT REACH THE SFC. FOR NOW...WILL
CONTINUE TO CARRY A DRY FCST SUN/SUN NIGHT WITH ANY PCPN PASSING N
OF UPPER MI. IF ANYTHING...WILL NEED TO WATCH FOR SOME LIGHT PCPN
CLIPPING THE KEWEENAW AND THE NE FCST AREA. SHALLOW MOISTURE
DROPPING INTO THE AREA BEHIND COLD FRONT ALONG WITH 850MB TEMPS
FALLING PERHAPS TO AROUND -12C MAY SUPPORT SOME LIGHT LES/FLURRIES
OFF LAKE SUPERIOR LATE SUN NIGHT INTO MON EVENING.
AS PREVIOUSLY MENTIONED...PATTERN NEXT WEEK WILL FEATURE LIMITED
PCPN CHANCES WITH TEMPS AVERAGING ABOVE NORMAL. AT THIS TIME...IT
APPEARS SHORTWAVES WILL PASS ACROSS THE AREA AT SOME POINT LATER
TUE/EARLY WED AND THEN THU. OF THE 2 SHORTWAVES...THE SECOND SHOULD
PROVIDE A BETTER CHC OF PCPN.
&&
.AVIATION /FOR THE 06Z TAF ISSUANCE/...
A FEW LEFTOVER LAKE EFFECT CLOUDS INTO KIWD WITH OCNL MVFR CIGS
SHOULD GIVE WAY TO CLEARING AS DRIER AIR AND LOW LEVEL RIDGING MOVES
IN. OTHERWISE...SOME MID CLOUDS WILL BE PUSHING ACROSS THE UPPER
LAKES WITH VFR CONDITIONS AT ALL THE TAF SITES. CEILINGS
WILL BEGIN TO LOWER FROM WEST TO EAST STARTING SAT MORNING AHEAD OF
AN UPPER LEVEL DISTURBANCE...BUT SHOULD NOT FALL INTO MVFR RANGE
UNTIL LATE MORNING OF AFTERNOON. AREAS OF LIGHT SNOW WILL ALSO
DEVELOP BUT VSBY SHOULD ALSO NOT FALL BELOW MVFR.
&&
.MARINE /FOR THE 4AM LAKE SUPERIOR FORECAST ISSUANCE/...
A SERIES OF LOW PRESSURE SYSTEMS MOVING THROUGH SOUTHERN CANADA WILL
PUSH SEVERAL SFC TROUGHS ACROSS LAKE SUPERIOR THROUGH THE FORECAST
PERIOD. FIRST TROUGH APPROACHES TODAY...WHICH WILL INCREASE WINDS TO
30KTS OUT OF THE SW TODAY...ALTHOUGH THERE COULD BE A FEW ISOLATED
GALE FORCE GUSTS OVER THE WRN LK. WINDS WILL DIMINISH OVERNIGHT
BEFORE INCREASING AGAIN SUNDAY AFTERNOON AHEAD OF THE NEXT TROUGH.
STRONG INVERSION JUST ABOVE THE SFC WILL LIKELY KEEP SUSTAINED WINDS
IN THE 20-30KT RANGE SUN AFTN AND NIGHT. DEPENDING ON THE STRENGTH
OF THE INVERSION...THERE MAY BE SOME GALE FORCE GUSTS TO 35KTS...DUE
TO WSW WINDS OF 40-50KTS 2-3KFT ABOVE THE LAKE. CONSIDERED ISSUING A
GALE WATCH...BUT WASN/T CONFIDENT ENOUGH ON GALES OCCURRING WITH THE
SW WINDS. THINK THE BEST CHANCE WILL BE AS WINDS TURN TO THE W IN
THE EVENING AND HAVE MENTIONED GALES IN THE TEXT. LIGHTER WINDS ARE
EXPECTED MON AFTN INTO MON NIGHT...BEFORE THE NEXT TROUGH APPROACHES
ON TUESDAY AND PRODUCES GUSTS TO 30KTS. THERE MAY BE A FEW GALE
FORCE GUSTS TO 35KTS OVER CENTRAL LAKE SUPERIOR TUESDAY AFTERNOON.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...NONE.
LAKE SUPERIOR...NONE.
LAKE MICHIGAN...NONE.
&&
$$
SYNOPSIS...ROLFSON
DISCUSSION...ROLFSON
AVIATION...JLB
MARINE...SRF
AREA FORECAST DISCUSSION...CORRECTED
NWS GLASGOW MT
1133 PM MST FRI DEC 16 2011
.SHORT TERM...FOR NORTHEAST MONTANA...TONIGHT...
UPDATE MADE EARLIER TO EXPAND DENSE FOG ADVISORY. CLEAR SKIES
WITH LIGHT WINDS AND AN INVERSION ALREADY IN PLACE LED TO DENSE
FOG FORMATION THIS AFTERNOON AND EVENING. FAIRLY STRONG SURFACE-
BASED INVERSION WITH SNOWCOVER SEEN ON 00Z KGGW SOUNDING...BUT
WITH ONLY A SHALLOW MOIST LAYER...AND 20KT WIND JUST OFF SURFACE.
WHILE SURFACE PRESSURE GRADIENTS ARE GENERALLY WEAK...NOT THE MOST
IDEAL FOR WIDESPREAD FOG...AS WIND IN SOME PLACES ENOUGH TO
PREVENT FOG FORMATION...MAINLY IN OUR SW. FOG LOOKING RATHER
PATCHY ON SATELLITE FOG LOOP ELSEWHERE.
MODELS INDICATE NOT MUCH CHANGE OVERNIGHT. RUC KEEPS A LARGE AREA
OF RELATIVE HUMIDITY ABOVE 95 PCT...CENTERED OVER VALLEY
COUNTY...WHICH LOOKS GOOD. WITH SOME WIND AND SHALLOWNESS OF THE
INVERSION THOUGH...EXPECT THE FOG TO BE QUITE CHANGEABLE...IN AND
OUT...AND PATCHY AT TIMES...BUT DENSE. THEREFORE DENSE FOG
ADVISORY MAINTAINED. MADE UPDATE FOR TEMPS AS SOME FORECAST LOWS
ALREADY SURPASSED. SIMONSEN
PREVIOUS SHORT TERM...FOR NORTHEAST
MONTANA...TONIGHT THROUGH SUNDAY...UPPER RIDGING WILL HOLD THROUGH
SUNDAY AFTERNOON...MAKING FOR WARMING TEMPERATURES AND DRY
CONDITIONS.
LOW CLOUDS AND STRATUS CONTINUE TO BE THE CHALLENGE OF THE
IMMEDIATE SHORT TERM. THE CLEARING LINE ON THE SOUTHERN EDGE OF
THE STRATUS DECK HAS CLEARED GLASGOW AND GLENDIVE AND IS
CONTINUING TO MOVE NORTHWARD. THIS BRINGS UP THE ISSUE OF THE
DENSE FOG ADVISORY...WHICH HAS BEEN EXTENDED THROUGH 9 PM. WITH
THAT SAID THERE IS SOME POTENTIAL FOR THE CLEARING TO HALT OR FOR
THE STRATUS/FOG TO REDEVELOP...CAUSING THE FOG TO LINGER
OVERNIGHT. WILL NEED TO BE MONITORED FOR SURE.
OTHERWISE TONIGHT EXPECT WARMER OVERNIGHT LOWS ACROSS THE
SOUTHWEST THANKS TO A CHINOOK IN CENTRAL MONTANA AND WESTERLY LOW
LEVEL FLOW. SOME POTENTIAL WILL REMAIN FOR RADIATIONAL FOG TO FORM
SO WILL KEEP IN MENTION OF FOG OVERNIGHT FOR MUCH OF THE AREA TONIGHT
INTO EARLY SATURDAY.
WITH THE CHINOOK IN FULL FORCE ACROSS CENTRAL MONTANA ON SATURDAY
EXPECT AN UNSEASONABLY WARM DAY ON SATURDAY AS SOUTHWEST WINDS
USHERING IN WARMER AIR. SATURDAY NIGHT THE WARM CONDITIONS WILL
PERSIST...WITH MIN TEMPS CLOSE TO CLIMATOLOGICAL MAX READINGS.
SUNDAY A COLD FRONT WILL SWEEP THROUGH NORTHEAST
MONTANA...BRINGING COOLER TEMPERATURES AND NORTHWEST WINDS. MODELS
CONTINUE TO SLIGHTLY DIFFER REGARDING THE ASSOCIATED UPPER
TROUGH...BUT ALL AGREE WITH THE BETTER POTENTIAL FOR PRECIP
FALLING ON SUNDAY NIGHT. WITH THAT SAID FELT THERE WAS ENOUGH POTENTIAL
FOR LIGHT SNOWFALL ACROSS THE NORTHWEST ZONES DURING THE
AFTERNOON TO WARRANT SLIGHT CHANCE POPS IN THE FORECAST. GILCHRIST
.LONG TERM...SUNDAY NIGHT THROUGH FRIDAY...
12Z GFS SLOWER WITH THE MID WEEK SYSTEM NOW AND OTHER MODELS ARE
DRIER THAN THE GFS. DID RAISE POPS A BIT FOR WEDNESDAY NIGHT FOR
THE SW ZONES AS OTHER MODELS ARE NARROWING ON A BETTER SOLUTION
WITH THIS SYSTEM. IT LOOKS LIKE MUCH OF THE MOISTURE WILL BE
AIMING MORE TOWARD THE WESTERN OR CENTRAL PORTION OF THE STATE.
LOW TEMPS WERE ADJUSTED SUNDAY AND MONDAY NIGHT. JAMBA
PREVIOUS DISCUSSION...
UPPER RIDGE REMAINS ALONG THE WEST COAST...WITH NO MAJOR WEATHER
SYSTEMS HEADING OUR WAY AFTER SUNDAY NIGHT. WE ARE ON THE E SIDE
OF THE RIDGE THOUGH...WHICH IS THE COLDER SIDE AS WE GET FRESH
INTRUSIONS OF POLAR AIR EVERY COUPLE OF DAYS OR SO. THIS IS
KEEPING TEMPS NEAR NORMAL.
THE MAIN SHORTWAVE HEADING OUR WAY FROM THE NW ARRIVES WED. ALL
MODELS HAVE A FAMILIAR (OF LATE) STRONG SPLITTING MOTION WITH IT.
EVEN SO... PAST 2 GFS RUNS GENERATE A SURPRISING AMOUNT OF
MOISTURE/QPF WHICH LOOKS OVERDONE. ALL OTHER MODELS ARE MUCH DRIER
AND PREFERRED. GFS ALSO APPEARS TOO FAST WITH THIS SYSTEM. SIMONSEN
&&
.AVIATION...
DENSE FOG CONTINUES NORTH OF THE MISSOURI RIVER THIS EVENING AND
SHOULD BEGIN TO SPREAD DOWN THE YELLOWSTONE RIVER VALLEY
OVERNIGHT. LOOK FOR IFR CONDITIONS BASED MAINLY ON VISIBILITY
TONIGHT FOR THE AREA. LOCALLY AT KGGW SKY IS PARTIALLY OBSCURED
WHERE STARS ARE VISIBLE ABOVE...HOWEVER HORIZONTAL VISIBILITY
LOWERS BELOW AN 1/8TH OF A MILE AT TIMES. CONDITIONS SHOULD
IMPROVE TO VFR AFTER 15Z AT ALL LOCATIONS. PROTON
&&
.GLASGOW WATCHES/WARNINGS/ADVISORIES...
DENSE FOG ADVISORY UNTIL 8 AM MST SATURDAY FOR CENTRAL AND
SOUTHEAST PHILLIPS...CENTRAL AND SOUTHERN VALLEY...DANIELS...
SHERIDAN...WESTERN ROOSEVELT...MCCONE...RICHLAND...DAWSON...
NORTHERN PHILLIPS...SOUTHWEST PHILLIPS...NORTHERN VALLEY...
EASTERN ROOSEVELT.
&&
$$
WEATHER.GOV/GLASGOW
AREA FORECAST DISCUSSION
NWS GLASGOW MT
1001 PM MST FRI DEC 16 2011
.SHORT TERM...FOR NORTHEAST MONTANA...TONIGHT...
UPDATE MADE EARLIER TO EXPAND DENSE FOG ADVISORY. CLEAR SKIES
WITH LIGHT WINDS AND AN INVERSION ALREADY IN PLACE LED TO DENSE
FOG FORMATION THIS AFTERNOON AND EVENING. FAIRLY STRONG SURFACE-
BASED INVERSION WITH SNOWCOVER SEEN ON 00Z KGGW SOUNDING...BUT
WITH ONLY A SHALLOW MOIST LAYER...AND 20KT WIND JUST OFF SURFACE.
WHILE SURFACE PRESSURE GRADIENTS ARE GENERALLY WEAK...NOT THE MOST
IDEAL FOR WIDESPREAD FOG...AS WIND IN SOME PLACES ENOUGH TO
PREVENT FOG FORMATION...MAINLY IN OUR SW. FOG LOOKING RATHER
PATCHY ON SATELLITE FOG LOOP ELSEWHERE.
MODELS INDICATE NOT MUCH CHANGE OVERNIGHT. RUC KEEPS A LARGE AREA
OF RELATIVE HUMIDITY ABOVE 95 PCT...CENTERED OVER VALLEY
COUNTY...WHICH LOOKS GOOD. WITH SOME WIND AND SHALLOWNESS OF THE
INVERSION THOUGH...EXPECT THE FOG TO BE QUITE CHANGEABLE...IN AND
OUT...AND PATCHY AT TIMES...BUT DENSE. THEREFORE DENSE FOG
ADVISORY MAINTAINED. MAN UPDATE FOR TEMPS AS SOME FORECAST LOWS
ALREADY SURPASSED. SIMONSEN
PREVIOUS SHORT TERM...FOR NORTHEAST
MONTANA...TONIGHT THROUGH SUNDAY...UPPER RIDGING WILL HOLD THROUGH
SUNDAY AFTERNOON...MAKING FOR WARMING TEMPERATURES AND DRY
CONDITIONS.
LOW CLOUDS AND STRATUS CONTINUE TO BE THE CHALLENGE OF THE
IMMEDIATE SHORT TERM. THE CLEARING LINE ON THE SOUTHERN EDGE OF
THE STRATUS DECK HAS CLEARED GLASGOW AND GLENDIVE AND IS
CONTINUING TO MOVE NORTHWARD. THIS BRINGS UP THE ISSUE OF THE
DENSE FOG ADVISORY...WHICH HAS BEEN EXTENDED THROUGH 9 PM. WITH
THAT SAID THERE IS SOME POTENTIAL FOR THE CLEARING TO HALT OR FOR
THE STRATUS/FOG TO REDEVELOP...CAUSING THE FOG TO LINGER
OVERNIGHT. WILL NEED TO BE MONITORED FOR SURE.
OTHERWISE TONIGHT EXPECT WARMER OVERNIGHT LOWS ACROSS THE
SOUTHWEST THANKS TO A CHINOOK IN CENTRAL MONTANA AND WESTERLY LOW
LEVEL FLOW. SOME POTENTIAL WILL REMAIN FOR RADIATIONAL FOG TO FORM
SO WILL KEEP IN MENTION OF FOG OVERNIGHT FOR MUCH OF THE AREA TONIGHT
INTO EARLY SATURDAY.
WITH THE CHINOOK IN FULL FORCE ACROSS CENTRAL MONTANA ON SATURDAY
EXPECT AN UNSEASONABLY WARM DAY ON SATURDAY AS SOUTHWEST WINDS
USHERING IN WARMER AIR. SATURDAY NIGHT THE WARM CONDITIONS WILL
PERSIST...WITH MIN TEMPS CLOSE TO CLIMATOLOGICAL MAX READINGS.
SUNDAY A COLD FRONT WILL SWEEP THROUGH NORTHEAST
MONTANA...BRINGING COOLER TEMPERATURES AND NORTHWEST WINDS. MODELS
CONTINUE TO SLIGHTLY DIFFER REGARDING THE ASSOCIATED UPPER
TROUGH...BUT ALL AGREE WITH THE BETTER POTENTIAL FOR PRECIP
FALLING ON SUNDAY NIGHT. WITH THAT SAID FELT THERE WAS ENOUGH POTENTIAL
FOR LIGHT SNOWFALL ACROSS THE NORTHWEST ZONES DURING THE
AFTERNOON TO WARRANT SLIGHT CHANCE POPS IN THE FORECAST. GILCHRIST
.LONG TERM...SUNDAY NIGHT THROUGH FRIDAY...
12Z GFS SLOWER WITH THE MID WEEK SYSTEM NOW AND OTHER MODELS ARE
DRIER THAN THE GFS. DID RAISE POPS A BIT FOR WEDNESDAY NIGHT FOR
THE SW ZONES AS OTHER MODELS ARE NARROWING ON A BETTER SOLUTION
WITH THIS SYSTEM. IT LOOKS LIKE MUCH OF THE MOISTURE WILL BE
AIMING MORE TOWARD THE WESTERN OR CENTRAL PORTION OF THE STATE.
LOW TEMPS WERE ADJUSTED SUNDAY AND MONDAY NIGHT. JAMBA
PREVIOUS DISCUSSION...
UPPER RIDGE REMAINS ALONG THE WEST COAST...WITH NO MAJOR WEATHER
SYSTEMS HEADING OUR WAY AFTER SUNDAY NIGHT. WE ARE ON THE E SIDE
OF THE RIDGE THOUGH...WHICH IS THE COLDER SIDE AS WE GET FRESH
INTRUSIONS OF POLAR AIR EVERY COUPLE OF DAYS OR SO. THIS IS
KEEPING TEMPS NEAR NORMAL.
THE MAIN SHORTWAVE HEADING OUR WAY FROM THE NW ARRIVES WED. ALL
MODELS HAVE A FAMILIAR (OF LATE) STRONG SPLITTING MOTION WITH IT.
EVEN SO... PAST 2 GFS RUNS GENERATE A SURPRISING AMOUNT OF
MOISTURE/QPF WHICH LOOKS OVERDONE. ALL OTHER MODELS ARE MUCH DRIER
AND PREFERRED. GFS ALSO APPEARS TOO FAST WITH THIS SYSTEM. SIMONSEN
&&
.AVIATION...
DENSE FOG CONTINUES NORTH OF THE MISSOURI RIVER THIS EVENING AND
SHOULD BEGIN TO SPREAD DOWN THE YELLOWSTONE RIVER VALLEY
OVERNIGHT. LOOK FOR IFR CONDITIONS BASED MAINLY ON VISIBILITY
TONIGHT FOR THE AREA. LOCALLY AT KGGW SKY IS PARTIALLY OBSCURED
WHERE STARS ARE VISIBLE ABOVE...HOWEVER HORIZONTAL VISIBILITY
LOWERS BELOW AN 1/8TH OF A MILE AT TIMES. CONDITIONS SHOULD
IMPROVE TO VFR AFTER 15Z AT ALL LOCATIONS. PROTON
&&
.GLASGOW WATCHES/WARNINGS/ADVISORIES...
DENSE FOG ADVISORY UNTIL 8 AM MST SATURDAY FOR CENTRAL AND
SOUTHEAST PHILLIPS...CENTRAL AND SOUTHERN VALLEY...DANIELS...
SHERIDAN...WESTERN ROOSEVELT...MCCONE...RICHLAND...DAWSON...
NORTHERN PHILLIPS...SOUTHWEST PHILLIPS...NORTHERN VALLEY...
EASTERN ROOSEVELT.
&&
$$
WEATHER.GOV/GLASGOW
AREA FORECAST DISCUSSION
NWS BINGHAMTON NY
1219 PM EST SAT DEC 17 2011
.SYNOPSIS...
LAKE EFFECT SNOW SHOWERS WILL COME TO AN END LATER TODAY AS HIGH
PRESSURE BUILDS IN OVER THE EAST COAST FOR THE REMAINDER OF THE
WEEKEND. A LOW PRESSURE SYSTEM WILL APPROACH THE AREA LATE
MONDAY...WHICH WILL BRING THE NEXT CHANCE OF PRECIPITATION WHICH
WILL BE THE MIDDLE OF THE WEEK.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
UPDATED AT 1030 AM...WEAK BACKDOOR-TYPE MESO FRONT EVIDENT OVER
LAKE ONTARIO INTO CNTRL CAYUGA AND SRN ONONDAGA/SRN MADISON...BEHIND
WHICH TD`S DROP OFF RAPIDLY. THIS LOW LVL DRYING IN COMBINATION
WITH DIURNAL EFFECTS WILL CONTINUE TO ERODE THE -SHSN ACTIVITY
CRNTLY OVER THE FCST AREA...ABD RDR TRENDS SUPPORT THIS WEAKENING.
FCST ON TRACK AND NO SIG CHGS ANTICIPATED. PREV BLO...
UPDATED AT 830 AM...FLURRIES AND SCT -SHSN ACRS THE RGN ATTM.
GRADUAL IMPRVMNT THIS AFTN BUT UNTIL THEN WE`LL SEE THE ACTIVITY
CONTINUE. TWEEKED 1ST PD POPS AND WX GRIDS OTRW NO CHGS. PREV BLO...
RADAR IMAGERY FROM BGM AND TYX, SHOWING LES IS COMING FROM A WNW
FLOW AND HAS SPREAD OUT MAINLY OVER ONEIDA, MADISON, AND ONONDAGA
COUNTIES. THERE MAY ALSO BE SOME LIGHT SNOW OVER OTSEGO COUNTY.
THESE SHOWERS SHOULD REMAIN LIGHT IN NATURE AND WILL GET LIGHTER
AS THE FLOW TURNS MORE NORTHERLY AND HIGH PRESSURE BUILDS IN.
LOOKING AT THE RADAR AND THE OBS, ANY HEAVIER SHOWERS, AND USING
THAT TERM LOOSELY, HAVE MOVED AWAY FROM THE LAKE SHORE. HOWEVER,
SOME ISOLATED SHOWERS MAY STILL DEVELOP NEAR THE LAKE SHORE AND
MOVE INTO THE CWA THROUGH THE MORNING HOURS. THE HRRR SHOWS MOST
OF THE ACTIVITY WELL TO THE SW OF THE CWA BY 20Z. OTHER MODELS
SHOW THEM DISSIPATING EVEN EARLIER. SO, TO SUM IT UP, FLURRIES TO
LIGHT SNOW SHOWERS POSSIBLE, MAINLY IN NEW YORK AND THE NORTHERN
TIER OF PA THROUGH MID AFTERNOON TO VERY EARLY EVENING. OTHERWISE,
CLOUDY BUT QUIET WEATHER TODAY.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH MONDAY NIGHT/...
HIGH PRESSURE WILL BUILD IN FOR THE REMAINDER OF THE WEEKEND AND
MONDAY. SUNDAYS TEMPS WILL BE NEAR NORMAL FOR THIS TIME OF YEAR.
THERE WILL BE A WARM UP ON MONDAY, WITH HIGHS REACHING INTO THE
LOW TO MID 40S. THIS IS AHEAD OF THE NEXT SYSTEM.
BY MONDAY AFTERNOON, A COLD FRONT, ASSOCIATED WITH A LOW PRESSURE
SYSTEM NEAR THE HUDSON BAY, WILL APPROACH THE AREA. MODELS ARE IN
PRETTY GOOD AGREEMENT, WITH THIS FRONT SLOWING AND STALLING MONDAY
NIGHT SOMEWHERE OVER THE CWA. THIS FRONT WILL BRING THE NEXT
CHANCE FOR RAIN AND SNOW SHOWERS TO THE AREA. MODELS ALSO
INDICATE, THAT THE PRECIPITATION SHOULD BE LIGHT AND THEN FIZZLE
OUT BY LATE MONDAY NIGHT/EARLY TUESDAY MORNING.
&&
.LONG TERM /TUESDAY THROUGH FRIDAY/...
LONG TERM IS DOMINATED OVERALL BY SOUTHWEST FLOW...WITH UNSETTLED
INTERRUPTION BY A COUPLE OF WAVES. NO MAJOR CONCERNS DISCERNIBLE
AT THIS TIME.
WEAKENING FRONT WILL SETTLE THROUGH THE AREA MONDAY NIGHT. GFS/ECWMF
BOTH SETTLE IT JUST SOUTH OF THE CWA TUESDAY...BEFORE RETURNING
NORTHWARD. HOWEVER...I ACCEPTED THE LOW CHANCE POPS OFFERED BY HPC
BECAUSE WITH FRONT BECOMING NEARLY FLOW-PARALLEL...IT MAY STRUGGLE
TO PUSH ALL THE WAY THROUGH AND COULD GET HUNG UP. ANY RESULTING
PRECIPITATION THOUGH WOULD BE VERY LIGHT.
ECMWF AND GFS ARE IN BETTER AGREEMENT ON AN UPPER LOW EJECTING OUT
OF THE SOUTHWEST U.S. AND OPENING UP WHILE GETTING ABSORBED INTO
THE WESTERLIES. WARM AIR ADVECTION AHEAD OF THE SYSTEM GETS
TEMPERATURES TO POINT WHERE PRECIPITATION SHOULD BE MAINLY RAIN...DURING
THE DAY WEDNESDAY...BUT UNCERTAINTY ON FRONT AND BACK ENDS FOR
PRECIPITATION TYPE. THOUGH NOT LIKELY...WINTRY MIX DURING THE
ONSET TUESDAY NIGHT IS NOT OUT OF THE QUESTION WITH ONLY SLIGHT
SHIFTS IN THE CURRENTLY PROJECTED TEMPERATURE PROFILES. THIS WILL
HAVE TO BE MONITORED. BECAUSE TIMING OF UPPER LOW EJECTION OUT OF
THE SOUTHWEST IS TYPICALLY SOMETHING THE MODELS STRUGGLE WITH...I
WENT AHEAD AND KEPT POPS IN CHANCE RANGE /40S-LOW 50S PCT/ TUESDAY
NIGHT AND WEDNESDAY UNTIL MORE MODEL RUNS CAN CONFIRM DETAILS
BETTER.
GFS/ECMWF DIVERGE AS WE HEAD LATE INTO THE WORKWEEK. BOTH REVERT TO
SOME SORT OF SOUTHWEST FLOW BUT ARE AT LEAST DAY OFF OF EACH
OTHER FOR WHEN TO SEND THE NEXT WAVE THROUGH THE FLOW. ECWMF HAS
WEAK AND DRY WAVE THURSDAY...GFS HAS A SLIGHTLY MORE AMPLIFIED
WAVE WAITING UNTIL FRIDAY...COMPLETE WITH GRADUALLY DEEPENING
SURFACE LOW OFF OF THE COAST. THE STRUGGLE APPEARS TO BE WHETHER
OR NOT THE SOUTHERN STREAM WAVE...CAN PHASE UP WITH A DIGGING
NORTHERN STREAM TROUGH. WITH SUCH UNCERTAINTY...KEEPING POPS IN
LINE WITH HPC...ONLY IN SLIGHT TO LOW CHANCE RANGE...PEAKING
FRIDAY.
&&
.AVIATION /18Z SATURDAY THROUGH WEDNESDAY/...
NORTHWEST WINDS ARE VEERING TO NORTH AS COLD AND DRY HIGH PRESSURE
BUILDS INTO THE AREA THIS AFTERNOON. WHAT IS LEFT OF THE LAKE
EFFECT FLURRIES...CURRENTLY AROUND KITH-KELM-KBGM...IS QUICKLY
COMING TO AN END WITH THE PUSH OF LOWER DEWPOINTS COMING IN FROM
THE NORTH. THIS AFTERNOON AND INTO TONIGHT...SOME
MOISTURE...ALBEIT LIMITED...REMAINS TRAPPED UNDER THE SUBSIDENCE
INVERSION. SO WHILE CLOUDS WILL SCATTER OUT AND IT WILL BE MAINLY
VFR THROUGH 18Z SUNDAY...THERE MAY BE SPOTS THIS AFTERNOON THROUGH
TONIGHT THAT WILL SOMETIMES CROSS THAT FINE SCT-BKN LINE FOR BRIEF
MVFR CIGS.
.OUTLOOK...
SUN AFTN THRU MON NGT...MAINLY VFR.
TUE/WED...POSSIBLE MVFR/IFR...ESPECIALLY TUE NGT AND WED AS SYSTEM
COMES THROUGH.
&&
.BGM WATCHES/WARNINGS/ADVISORIES...
PA...NONE.
NY...NONE.
&&
$$
SYNOPSIS...SLI
NEAR TERM...
SHORT TERM...SLI
LONG TERM...MDP
AVIATION...MDP
AREA FORECAST DISCUSSION
NWS BINGHAMTON NY
1031 AM EST SAT DEC 17 2011
.SYNOPSIS...
LAKE EFFECT SNOW SHOWERS WILL COME TO AN END LATER TODAY AS HIGH
PRESSURE BUILDS IN OVER THE EAST COAST FOR THE REMAINDER OF THE
WEEKEND. A LOW PRESSURE SYSTEM WILL APPROACH THE AREA LATE
MONDAY...WHICH WILL BRING THE NEXT CHANCE OF PRECIPITATION WHICH
WILL BE THE MIDDLE OF THE WEEK.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
UPDATED AT 1030 AM...WEAK BACKDOOR-TYPE MESO FRONT EVIDENT OVER
LAKE ONTARIO INTO CNTRL CAYUGA AND SRN ONONDAGA/SRN MADISON...BEHIND
WHICH TD`S DROP OFF RAPIDLY. THIS LOW LVL DRYING IN COMBINATION
WITH DIURNAL EFFECTS WILL CONTINUE TO ERODE THE -SHSN ACTIVITY
CRNTLY OVER THE FCST AREA...ABD RDR TRENDS SUPPORT THIS WEAKENING.
FCST ON TRACK AND NO SIG CHGS ANTICIPATED. PREV BLO...
UPDATED AT 830 AM...FLURRIES AND SCT -SHSN ACRS THE RGN ATTM.
GRADUAL IMPRVMNT THIS AFTN BUT UNTIL THEN WE`LL SEE THE ACTIVITY
CONTINUE. TWEEKED 1ST PD POPS AND WX GRIDS OTRW NO CHGS. PREV BLO...
RADAR IMAGERY FROM BGM AND TYX, SHOWING LES IS COMING FROM A WNW
FLOW AND HAS SPREAD OUT MAINLY OVER ONEIDA, MADISON, AND ONONDAGA
COUNTIES. THERE MAY ALSO BE SOME LIGHT SNOW OVER OTSEGO COUNTY.
THESE SHOWERS SHOULD REMAIN LIGHT IN NATURE AND WILL GET LIGHTER
AS THE FLOW TURNS MORE NORTHERLY AND HIGH PRESSURE BUILDS IN.
LOOKING AT THE RADAR AND THE OBS, ANY HEAVIER SHOWERS, AND USING
THAT TERM LOOSELY, HAVE MOVED AWAY FROM THE LAKE SHORE. HOWEVER,
SOME ISOLATED SHOWERS MAY STILL DEVELOP NEAR THE LAKE SHORE AND
MOVE INTO THE CWA THROUGH THE MORNING HOURS. THE HRRR SHOWS MOST
OF THE ACTIVITY WELL TO THE SW OF THE CWA BY 20Z. OTHER MODELS
SHOW THEM DISSIPATING EVEN EARLIER. SO, TO SUM IT UP, FLURRIES TO
LIGHT SNOW SHOWERS POSSIBLE, MAINLY IN NEW YORK AND THE NORTHERN
TIER OF PA THROUGH MID AFTERNOON TO VERY EARLY EVENING. OTHERWISE,
CLOUDY BUT QUIET WEATHER TODAY.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH MONDAY NIGHT/...
HIGH PRESSURE WILL BUILD IN FOR THE REMAINDER OF THE WEEKEND AND
MONDAY. SUNDAYS TEMPS WILL BE NEAR NORMAL FOR THIS TIME OF YEAR.
THERE WILL BE A WARM UP ON MONDAY, WITH HIGHS REACHING INTO THE
LOW TO MID 40S. THIS IS AHEAD OF THE NEXT SYSTEM.
BY MONDAY AFTERNOON, A COLD FRONT, ASSOCIATED WITH A LOW PRESSURE
SYSTEM NEAR THE HUDSON BAY, WILL APPROACH THE AREA. MODELS ARE IN
PRETTY GOOD AGREEMENT, WITH THIS FRONT SLOWING AND STALLING MONDAY
NIGHT SOMEWHERE OVER THE CWA. THIS FRONT WILL BRING THE NEXT
CHANCE FOR RAIN AND SNOW SHOWERS TO THE AREA. MODELS ALSO
INDICATE, THAT THE PRECIPITATION SHOULD BE LIGHT AND THEN FIZZLE
OUT BY LATE MONDAY NIGHT/EARLY TUESDAY MORNING.
&&
.LONG TERM /TUESDAY THROUGH FRIDAY/...
LONG TERM IS DOMINATED OVERALL BY SOUTHWEST FLOW...WITH UNSETTLED
INTERRUPTION BY A COUPLE OF WAVES. NO MAJOR CONCERNS DISCERNIBLE
AT THIS TIME.
WEAKENING FRONT WILL SETTLE THROUGH THE AREA MONDAY NIGHT. GFS/ECWMF
BOTH SETTLE IT JUST SOUTH OF THE CWA TUESDAY...BEFORE RETURNING
NORTHWARD. HOWEVER...I ACCEPTED THE LOW CHANCE POPS OFFERED BY HPC
BECAUSE WITH FRONT BECOMING NEARLY FLOW-PARALLEL...IT MAY STRUGGLE
TO PUSH ALL THE WAY THROUGH AND COULD GET HUNG UP. ANY RESULTING
PRECIPITATION THOUGH WOULD BE VERY LIGHT.
ECMWF AND GFS ARE IN BETTER AGREEMENT ON AN UPPER LOW EJECTING OUT
OF THE SOUTHWEST U.S. AND OPENING UP WHILE GETTING ABSORBED INTO
THE WESTERLIES. WARM AIR ADVECTION AHEAD OF THE SYSTEM GETS
TEMPERATURES TO POINT WHERE PRECIPITATION SHOULD BE MAINLY RAIN...DURING
THE DAY WEDNESDAY...BUT UNCERTAINTY ON FRONT AND BACK ENDS FOR
PRECIPITATION TYPE. THOUGH NOT LIKELY...WINTRY MIX DURING THE
ONSET TUESDAY NIGHT IS NOT OUT OF THE QUESTION WITH ONLY SLIGHT
SHIFTS IN THE CURRENTLY PROJECTED TEMPERATURE PROFILES. THIS WILL
HAVE TO BE MONITORED. BECAUSE TIMING OF UPPER LOW EJECTION OUT OF
THE SOUTHWEST IS TYPICALLY SOMETHING THE MODELS STRUGGLE WITH...I
WENT AHEAD AND KEPT POPS IN CHANCE RANGE /40S-LOW 50S PCT/ TUESDAY
NIGHT AND WEDNESDAY UNTIL MORE MODEL RUNS CAN CONFIRM DETAILS
BETTER.
GFS/ECMWF DIVERGE AS WE HEAD LATE INTO THE WORKWEEK. BOTH REVERT TO
SOME SORT OF SOUTHWEST FLOW BUT ARE AT LEAST DAY OFF OF EACH
OTHER FOR WHEN TO SEND THE NEXT WAVE THROUGH THE FLOW. ECWMF HAS
WEAK AND DRY WAVE THURSDAY...GFS HAS A SLIGHTLY MORE AMPLIFIED
WAVE WAITING UNTIL FRIDAY...COMPLETE WITH GRADUALLY DEEPENING
SURFACE LOW OFF OF THE COAST. THE STRUGGLE APPEARS TO BE WHETHER
OR NOT THE SOUTHERN STREAM WAVE...CAN PHASE UP WITH A DIGGING
NORTHERN STREAM TROUGH. WITH SUCH UNCERTAINTY...KEEPING POPS IN
LINE WITH HPC...ONLY IN SLIGHT TO LOW CHANCE RANGE...PEAKING
FRIDAY.
&&
.AVIATION /16Z SATURDAY THROUGH WEDNESDAY/...
A NW FLOW OFF LAKE ONTARIO WILL KEEP LE SNOW SHWRS IN THE AREA
THRU ABT 15Z WITH MVFR AND OCNL IFR CIGS DOWNWIND OF THE LAKE AT
ITH AND BGM. ELSEWHERE GNRL VFR CONDS THIS MRNG WITH SCT LGT SNOW
SHWRS. DRIER AIR MVG IN LTR THIS MRNG AND THRU THE END OF THE PD
WILL END MUCH OF THE LAKE EFFECT AND BRING VFR CONDS THRU 12Z SUN.
.OUTLOOK...
SAT NGT THRU MON NGT...MAINLY VFR.
TUE/WED...POSSIBLE MVFR/IFR...ESPECIALLY TUE NGT AND WED AS SYSTEM
COMES THROUGH.
&&
.BGM WATCHES/WARNINGS/ADVISORIES...
PA...NONE.
NY...NONE.
&&
$$
SYNOPSIS...SLI
NEAR TERM...
SHORT TERM...SLI
LONG TERM...MDP
AVIATION...DGM
AREA FORECAST DISCUSSION
NWS BINGHAMTON NY
832 AM EST SAT DEC 17 2011
.SYNOPSIS...
LAKE EFFECT SNOW SHOWERS WILL COME TO AN END LATER TODAY AS HIGH
PRESSURE BUILDS IN OVER THE EAST COAST FOR THE REMAINDER OF THE
WEEKEND. A LOW PRESSURE SYSTEM WILL APPROACH THE AREA LATE
MONDAY...WHICH WILL BRING THE NEXT CHANCE OF PRECIPITATION WHICH
WILL BE THE MIDDLE OF THE WEEK.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
UPDATED AT 830 AM...FLURRIES AND SCT -SHSN ACRS THE RGN ATTM.
GRADUAL IMPRVMNT THIS AFTN BUT UNTIL THEN WE`LL SEE THE ACTIVITY
CONTINUE. TWEEKED 1ST PD POPS AND WX GRIDS OTRW NO CHGS. PREV BLO...
RADAR IMAGERY FROM BGM AND TYX, SHOWING LES IS COMING FROM A WNW
FLOW AND HAS SPREAD OUT MAINLY OVER ONEIDA, MADISON, AND ONONDAGA
COUNTIES. THERE MAY ALSO BE SOME LIGHT SNOW OVER OTSEGO COUNTY.
THESE SHOWERS SHOULD REMAIN LIGHT IN NATURE AND WILL GET LIGHTER
AS THE FLOW TURNS MORE NORTHERLY AND HIGH PRESSURE BUILDS IN.
LOOKING AT THE RADAR AND THE OBS, ANY HEAVIER SHOWERS, AND USING
THAT TERM LOOSELY, HAVE MOVED AWAY FROM THE LAKE SHORE. HOWEVER,
SOME ISOLATED SHOWERS MAY STILL DEVELOP NEAR THE LAKE SHORE AND
MOVE INTO THE CWA THROUGH THE MORNING HOURS. THE HRRR SHOWS MOST
OF THE ACTIVITY WELL TO THE SW OF THE CWA BY 20Z. OTHER MODELS
SHOW THEM DISSIPATING EVEN EARLIER. SO, TO SUM IT UP, FLURRIES TO
LIGHT SNOW SHOWERS POSSIBLE, MAINLY IN NEW YORK AND THE NORTHERN
TIER OF PA THROUGH MID AFTERNOON TO VERY EARLY EVENING. OTHERWISE,
CLOUDY BUT QUIET WEATHER TODAY.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH MONDAY NIGHT/...
HIGH PRESSURE WILL BUILD IN FOR THE REMAINDER OF THE WEEKEND AND
MONDAY. SUNDAYS TEMPS WILL BE NEAR NORMAL FOR THIS TIME OF YEAR.
THERE WILL BE A WARM UP ON MONDAY, WITH HIGHS REACHING INTO THE
LOW TO MID 40S. THIS IS AHEAD OF THE NEXT SYSTEM.
BY MONDAY AFTERNOON, A COLD FRONT, ASSOCIATED WITH A LOW PRESSURE
SYSTEM NEAR THE HUDSON BAY, WILL APPROACH THE AREA. MODELS ARE IN
PRETTY GOOD AGREEMENT, WITH THIS FRONT SLOWING AND STALLING MONDAY
NIGHT SOMEWHERE OVER THE CWA. THIS FRONT WILL BRING THE NEXT
CHANCE FOR RAIN AND SNOW SHOWERS TO THE AREA. MODELS ALSO
INDICATE, THAT THE PRECIPITATION SHOULD BE LIGHT AND THEN FIZZLE
OUT BY LATE MONDAY NIGHT/EARLY TUESDAY MORNING.
&&
.LONG TERM /TUESDAY THROUGH FRIDAY/...
LONG TERM IS DOMINATED OVERALL BY SOUTHWEST FLOW...WITH UNSETTLED
INTERRUPTION BY A COUPLE OF WAVES. NO MAJOR CONCERNS DISCERNIBLE
AT THIS TIME.
WEAKENING FRONT WILL SETTLE THROUGH THE AREA MONDAY NIGHT. GFS/ECWMF
BOTH SETTLE IT JUST SOUTH OF THE CWA TUESDAY...BEFORE RETURNING
NORTHWARD. HOWEVER...I ACCEPTED THE LOW CHANCE POPS OFFERED BY HPC
BECAUSE WITH FRONT BECOMING NEARLY FLOW-PARALLEL...IT MAY STRUGGLE
TO PUSH ALL THE WAY THROUGH AND COULD GET HUNG UP. ANY RESULTING
PRECIPITATION THOUGH WOULD BE VERY LIGHT.
ECMWF AND GFS ARE IN BETTER AGREEMENT ON AN UPPER LOW EJECTING OUT
OF THE SOUTHWEST U.S. AND OPENING UP WHILE GETTING ABSORBED INTO
THE WESTERLIES. WARM AIR ADVECTION AHEAD OF THE SYSTEM GETS
TEMPERATURES TO POINT WHERE PRECIPITATION SHOULD BE MAINLY RAIN...DURING
THE DAY WEDNESDAY...BUT UNCERTAINTY ON FRONT AND BACK ENDS FOR
PRECIPITATION TYPE. THOUGH NOT LIKELY...WINTRY MIX DURING THE
ONSET TUESDAY NIGHT IS NOT OUT OF THE QUESTION WITH ONLY SLIGHT
SHIFTS IN THE CURRENTLY PROJECTED TEMPERATURE PROFILES. THIS WILL
HAVE TO BE MONITORED. BECAUSE TIMING OF UPPER LOW EJECTION OUT OF
THE SOUTHWEST IS TYPICALLY SOMETHING THE MODELS STRUGGLE WITH...I
WENT AHEAD AND KEPT POPS IN CHANCE RANGE /40S-LOW 50S PCT/ TUESDAY
NIGHT AND WEDNESDAY UNTIL MORE MODEL RUNS CAN CONFIRM DETAILS
BETTER.
GFS/ECMWF DIVERGE AS WE HEAD LATE INTO THE WORKWEEK. BOTH REVERT TO
SOME SORT OF SOUTHWEST FLOW BUT ARE AT LEAST DAY OFF OF EACH
OTHER FOR WHEN TO SEND THE NEXT WAVE THROUGH THE FLOW. ECWMF HAS
WEAK AND DRY WAVE THURSDAY...GFS HAS A SLIGHTLY MORE AMPLIFIED
WAVE WAITING UNTIL FRIDAY...COMPLETE WITH GRADUALLY DEEPENING
SURFACE LOW OFF OF THE COAST. THE STRUGGLE APPEARS TO BE WHETHER
OR NOT THE SOUTHERN STREAM WAVE...CAN PHASE UP WITH A DIGGING
NORTHERN STREAM TROUGH. WITH SUCH UNCERTAINTY...KEEPING POPS IN
LINE WITH HPC...ONLY IN SLIGHT TO LOW CHANCE RANGE...PEAKING
FRIDAY.
&&
.AVIATION /14Z SATURDAY THROUGH WEDNESDAY/...
A NW FLOW OFF LAKE ONTARIO WILL KEEP LE SNOW SHWRS IN THE AREA
THRU ABT 15Z WITH MVFR AND OCNL IFR CIGS DOWNWIND OF THE LAKE AT
ITH AND BGM. ELSEWHERE GNRL VFR CONDS THIS MRNG WITH SCT LGT SNOW
SHWRS. DRIER AIR MVG IN LTR THIS MRNG AND THRU THE END OF THE PD
WILL END MUCH OF THE LAKE EFFECT AND BRING VFR CONDS THRU 12Z SUN.
.OUTLOOK...
SAT NGT THRU MON NGT...MAINLY VFR.
TUE/WED...POSSIBLE MVFR/IFR...ESPECIALLY TUE NGT AND WED AS SYSTEM
COMES THROUGH.
&&
.BGM WATCHES/WARNINGS/ADVISORIES...
PA...NONE.
NY...NONE.
&&
$$
SYNOPSIS...SLI
NEAR TERM...SLI
SHORT TERM...SLI
LONG TERM...MDP
AVIATION...DGM
AREA FORECAST DISCUSSION
NWS BINGHAMTON NY
752 AM EST SAT DEC 17 2011
.SYNOPSIS...
LAKE EFFECT SNOW SHOWERS WILL COME TO AN END LATER TODAY AS HIGH
PRESSURE BUILDS IN OVER THE EAST COAST FOR THE REMAINDER OF THE
WEEKEND. A LOW PRESSURE SYSTEM WILL APPROACH THE AREA LATE
MONDAY...WHICH WILL BRING THE NEXT CHANCE OF PRECIPITATION WHICH
WILL BE THE MIDDLE OF THE WEEK.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
RADAR IMAGERY FROM BGM AND TYX, SHOWING LES IS COMING FROM A WNW
FLOW AND HAS SPREAD OUT MAINLY OVER ONEIDA, MADISON, AND ONONDAGA
COUNTIES. THERE MAY ALSO BE SOME LIGHT SNOW OVER OTSEGO COUNTY.
THESE SHOWERS SHOULD REMAIN LIGHT IN NATURE AND WILL GET LIGHTER
AS THE FLOW TURNS MORE NORTHERLY AND HIGH PRESSURE BUILDS IN.
LOOKING AT THE RADAR AND THE OBS, ANY HEAVIER SHOWERS, AND USING
THAT TERM LOOSELY, HAVE MOVED AWAY FROM THE LAKE SHORE. HOWEVER,
SOME ISOLATED SHOWERS MAY STILL DEVELOP NEAR THE LAKE SHORE AND
MOVE INTO THE CWA THROUGH THE MORNING HOURS. THE HRRR SHOWS MOST
OF THE ACTIVITY WELL TO THE SW OF THE CWA BY 20Z. OTHER MODELS
SHOW THEM DISSIPATING EVEN EARLIER. SO, TO SUM IT UP, FLURRIES TO
LIGHT SNOW SHOWERS POSSIBLE, MAINLY IN NEW YORK AND THE NORTHERN
TIER OF PA THROUGH MID AFTERNOON TO VERY EARLY EVENING. OTHERWISE,
CLOUDY BUT QUIET WEATHER TODAY.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH MONDAY NIGHT/...
HIGH PRESSURE WILL BUILD IN FOR THE REMAINDER OF THE WEEKEND AND
MONDAY. SUNDAYS TEMPS WILL BE NEAR NORMAL FOR THIS TIME OF YEAR.
THERE WILL BE A WARM UP ON MONDAY, WITH HIGHS REACHING INTO THE
LOW TO MID 40S. THIS IS AHEAD OF THE NEXT SYSTEM.
BY MONDAY AFTERNOON, A COLD FRONT, ASSOCIATED WITH A LOW PRESSURE
SYSTEM NEAR THE HUDSON BAY, WILL APPROACH THE AREA. MODELS ARE IN
PRETTY GOOD AGREEMENT, WITH THIS FRONT SLOWING AND STALLING MONDAY
NIGHT SOMEWHERE OVER THE CWA. THIS FRONT WILL BRING THE NEXT
CHANCE FOR RAIN AND SNOW SHOWERS TO THE AREA. MODELS ALSO
INDICATE, THAT THE PRECIPITATION SHOULD BE LIGHT AND THEN FIZZLE
OUT BY LATE MONDAY NIGHT/EARLY TUESDAY MORNING.
&&
.LONG TERM /TUESDAY THROUGH FRIDAY/...
LONG TERM IS DOMINATED OVERALL BY SOUTHWEST FLOW...WITH UNSETTLED
INTERRUPTION BY A COUPLE OF WAVES. NO MAJOR CONCERNS DISCERNIBLE
AT THIS TIME.
WEAKENING FRONT WILL SETTLE THROUGH THE AREA MONDAY NIGHT. GFS/ECWMF
BOTH SETTLE IT JUST SOUTH OF THE CWA TUESDAY...BEFORE RETURNING
NORTHWARD. HOWEVER...I ACCEPTED THE LOW CHANCE POPS OFFERED BY HPC
BECAUSE WITH FRONT BECOMING NEARLY FLOW-PARALLEL...IT MAY STRUGGLE
TO PUSH ALL THE WAY THROUGH AND COULD GET HUNG UP. ANY RESULTING
PRECIPITATION THOUGH WOULD BE VERY LIGHT.
ECMWF AND GFS ARE IN BETTER AGREEMENT ON AN UPPER LOW EJECTING OUT
OF THE SOUTHWEST U.S. AND OPENING UP WHILE GETTING ABSORBED INTO
THE WESTERLIES. WARM AIR ADVECTION AHEAD OF THE SYSTEM GETS
TEMPERATURES TO POINT WHERE PRECIPITATION SHOULD BE MAINLY RAIN...DURING
THE DAY WEDNESDAY...BUT UNCERTAINTY ON FRONT AND BACK ENDS FOR
PRECIPITATION TYPE. THOUGH NOT LIKELY...WINTRY MIX DURING THE
ONSET TUESDAY NIGHT IS NOT OUT OF THE QUESTION WITH ONLY SLIGHT
SHIFTS IN THE CURRENTLY PROJECTED TEMPERATURE PROFILES. THIS WILL
HAVE TO BE MONITORED. BECAUSE TIMING OF UPPER LOW EJECTION OUT OF
THE SOUTHWEST IS TYPICALLY SOMETHING THE MODELS STRUGGLE WITH...I
WENT AHEAD AND KEPT POPS IN CHANCE RANGE /40S-LOW 50S PCT/ TUESDAY
NIGHT AND WEDNESDAY UNTIL MORE MODEL RUNS CAN CONFIRM DETAILS
BETTER.
GFS/ECMWF DIVERGE AS WE HEAD LATE INTO THE WORKWEEK. BOTH REVERT TO
SOME SORT OF SOUTHWEST FLOW BUT ARE AT LEAST DAY OFF OF EACH
OTHER FOR WHEN TO SEND THE NEXT WAVE THROUGH THE FLOW. ECWMF HAS
WEAK AND DRY WAVE THURSDAY...GFS HAS A SLIGHTLY MORE AMPLIFIED
WAVE WAITING UNTIL FRIDAY...COMPLETE WITH GRADUALLY DEEPENING
SURFACE LOW OFF OF THE COAST. THE STRUGGLE APPEARS TO BE WHETHER
OR NOT THE SOUTHERN STREAM WAVE...CAN PHASE UP WITH A DIGGING
NORTHERN STREAM TROUGH. WITH SUCH UNCERTAINTY...KEEPING POPS IN
LINE WITH HPC...ONLY IN SLIGHT TO LOW CHANCE RANGE...PEAKING
FRIDAY.
&&
.AVIATION /13Z SATURDAY THROUGH WEDNESDAY/...
A NW FLOW OFF LAKE ONTARIO WILL KEEP LE SNOW SHWRS IN THE AREA
THRU ABT 15Z WITH MVFR AND OCNL IFR CIGS DOWNWIND OF THE LAKE AT
ITH AND BGM. ELSEWHERE GNRL VFR CONDS THIS MRNG WITH SCT LGT SNOW
SHWRS. DRIER AIR MVG IN LTR THIS MRNG AND THRU THE END OF THE PD
WILL END MUCH OF THE LAKE EFFECT AND BRING VFR CONDS THRU 12Z SUN.
.OUTLOOK...
SAT NGT THRU MON NGT...MAINLY VFR.
TUE/WED...POSSIBLE MVFR/IFR...ESPECIALLY TUE NGT AND WED AS SYSTEM
COMES THROUGH.
&&
.BGM WATCHES/WARNINGS/ADVISORIES...
PA...NONE.
NY...NONE.
&&
$$
SYNOPSIS...SLI
NEAR TERM...SLI
SHORT TERM...SLI
LONG TERM...MDP
AVIATION...DGM
AREA FORECAST DISCUSSION
NWS BINGHAMTON NY
643 AM EST SAT DEC 17 2011
.SYNOPSIS...
LAKE EFFECT SNOW SHOWERS WILL COME TO AN END LATER TODAY AS HIGH
PRESSURE BUILDS IN OVER THE EAST COAST FOR THE REMAINDER OF THE
WEEKEND. A LOW PRESSURE SYSTEM WILL APPROACH THE AREA LATE
MONDAY...WHICH WILL BRING THE NEXT CHANCE OF PRECIPITATION WHICH
WILL BE THE MIDDLE OF THE WEEK.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
RADAR IMAGERY FROM BGM AND TYX, SHOWING LES IS COMING FROM A WNW
FLOW AND HAS SPREAD OUT MAINLY OVER ONEIDA, MADISON, AND ONONDAGA
COUNTIES. THERE MAY ALSO BE SOME LIGHT SNOW OVER OTSEGO COUNTY.
THESE SHOWERS SHOULD REMAIN LIGHT IN NATURE AND WILL GET LIGHTER
AS THE FLOW TURNS MORE NORTHERLY AND HIGH PRESSURE BUILDS IN.
LOOKING AT THE RADAR AND THE OBS, ANY HEAVIER SHOWERS, AND USING
THAT TERM LOOSELY, HAVE MOVED AWAY FROM THE LAKE SHORE. HOWEVER,
SOME ISOLATED SHOWERS MAY STILL DEVELOP NEAR THE LAKE SHORE AND
MOVE INTO THE CWA THROUGH THE MORNING HOURS. THE HRRR SHOWS MOST
OF THE ACTIVITY WELL TO THE SW OF THE CWA BY 20Z. OTHER MODELS
SHOW THEM DISSIPATING EVEN EARLIER. SO, TO SUM IT UP, FLURRIES TO
LIGHT SNOW SHOWERS POSSIBLE, MAINLY IN NEW YORK AND THE NORTHERN
TIER OF PA THROUGH MID AFTERNOON TO VERY EARLY EVENING. OTHERWISE,
CLOUDY BUT QUIET WEATHER TODAY.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH MONDAY NIGHT/...
HIGH PRESSURE WILL BUILD IN FOR THE REMAINDER OF THE WEEKEND AND
MONDAY. SUNDAYS TEMPS WILL BE NEAR NORMAL FOR THIS TIME OF YEAR.
THERE WILL BE A WARM UP ON MONDAY, WITH HIGHS REACHING INTO THE
LOW TO MID 40S. THIS IS AHEAD OF THE NEXT SYSTEM.
BY MONDAY AFTERNOON, A COLD FRONT, ASSOCIATED WITH A LOW PRESSURE
SYSTEM NEAR THE HUDSON BAY, WILL APPROACH THE AREA. MODELS ARE IN
PRETTY GOOD AGREEMENT, WITH THIS FRONT SLOWING AND STALLING MONDAY
NIGHT SOMEWHERE OVER THE CWA. THIS FRONT WILL BRING THE NEXT
CHANCE FOR RAIN AND SNOW SHOWERS TO THE AREA. MODELS ALSO
INDICATE, THAT THE PRECIPITATION SHOULD BE LIGHT AND THEN FIZZLE
OUT BY LATE MONDAY NIGHT/EARLY TUESDAY MORNING.
&&
.LONG TERM /TUESDAY THROUGH FRIDAY/...
LONG TERM IS DOMINATED OVERALL BY SOUTHWEST FLOW...WITH UNSETTLED
INTERRUPTION BY A COUPLE OF WAVES. NO MAJOR CONCERNS DISCERNIBLE
AT THIS TIME.
WEAKENING FRONT WILL SETTLE THROUGH THE AREA MONDAY NIGHT. GFS/ECWMF
BOTH SETTLE IT JUST SOUTH OF THE CWA TUESDAY...BEFORE RETURNING
NORTHWARD. HOWEVER...I ACCEPTED THE LOW CHANCE POPS OFFERED BY HPC
BECAUSE WITH FRONT BECOMING NEARLY FLOW-PARALLEL...IT MAY STRUGGLE
TO PUSH ALL THE WAY THROUGH AND COULD GET HUNG UP. ANY RESULTING
PRECIPITATION THOUGH WOULD BE VERY LIGHT.
ECMWF AND GFS ARE IN BETTER AGREEMENT ON AN UPPER LOW EJECTING OUT
OF THE SOUTHWEST U.S. AND OPENING UP WHILE GETTING ABSORBED INTO
THE WESTERLIES. WARM AIR ADVECTION AHEAD OF THE SYSTEM GETS
TEMPERATURES TO POINT WHERE PRECIPITATION SHOULD BE MAINLY RAIN...DURING
THE DAY WEDNESDAY...BUT UNCERTAINTY ON FRONT AND BACK ENDS FOR
PRECIPITATION TYPE. THOUGH NOT LIKELY...WINTRY MIX DURING THE
ONSET TUESDAY NIGHT IS NOT OUT OF THE QUESTION WITH ONLY SLIGHT
SHIFTS IN THE CURRENTLY PROJECTED TEMPERATURE PROFILES. THIS WILL
HAVE TO BE MONITORED. BECAUSE TIMING OF UPPER LOW EJECTION OUT OF
THE SOUTHWEST IS TYPICALLY SOMETHING THE MODELS STRUGGLE WITH...I
WENT AHEAD AND KEPT POPS IN CHANCE RANGE /40S-LOW 50S PCT/ TUESDAY
NIGHT AND WEDNESDAY UNTIL MORE MODEL RUNS CAN CONFIRM DETAILS
BETTER.
GFS/ECMWF DIVERGE AS WE HEAD LATE INTO THE WORKWEEK. BOTH REVERT TO
SOME SORT OF SOUTHWEST FLOW BUT ARE AT LEAST DAY OFF OF EACH
OTHER FOR WHEN TO SEND THE NEXT WAVE THROUGH THE FLOW. ECWMF HAS
WEAK AND DRY WAVE THURSDAY...GFS HAS A SLIGHTLY MORE AMPLIFIED
WAVE WAITING UNTIL FRIDAY...COMPLETE WITH GRADUALLY DEEPENING
SURFACE LOW OFF OF THE COAST. THE STRUGGLE APPEARS TO BE WHETHER
OR NOT THE SOUTHERN STREAM WAVE...CAN PHASE UP WITH A DIGGING
NORTHERN STREAM TROUGH. WITH SUCH UNCERTAINTY...KEEPING POPS IN
LINE WITH HPC...ONLY IN SLIGHT TO LOW CHANCE RANGE...PEAKING
FRIDAY.
&&
.AVIATION /12Z SATURDAY THROUGH WEDNESDAY/...
A NW FLOW OFF LAKE ONTARIO WILL KEEP LE SNOW SHWRS IN THE AREA
THRU ABT 15Z WITH MVFR AND OCNL IFR CIGS DOWNWIND OF THE LAKE AT
ITH AND BGM. ELSEWHERE GNRL VFR CONDS THIS MRNG WITH SCT LGT SNOW
SHWRS. DRIER AIR MVG IN LTR THIS MRNG AND THRU THE END OF THE PD
WILL END MUCH OF THE LAKE EFFECT AND BRING VFR CONDS THRU 12Z SUN.
.OUTLOOK...
SAT NGT THRU MON NGT...MAINLY VFR.
TUE/WED...POSSIBLE MVFR/IFR...ESPECIALLY TUE NGT AND WED AS SYSTEM
COMES THROUGH.
&&
.BGM WATCHES/WARNINGS/ADVISORIES...
PA...NONE.
NY...NONE.
&&
$$
SYNOPSIS...SLI
NEAR TERM...SLI
SHORT TERM...SLI
LONG TERM...MDP
AVIATION...DGM
AREA FORECAST DISCUSSION
NWS BINGHAMTON NY
412 AM EST SAT DEC 17 2011
.SYNOPSIS...
LAKE EFFECT SNOW SHOWERS WILL COME TO AN END LATER TODAY AS HIGH
PRESSURE BUILDS IN OVER THE EAST COAST FOR THE REMAINDER OF THE
WEEKEND. A LOW PRESSURE SYSTEM WILL APPROACH THE AREA LATE
MONDAY...WHICH WILL BRING THE NEXT CHANCE OF PRECIPITATION WHICH
WILL BE THE MIDDLE OF THE WEEK.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
RADAR IMAGERY FROM BGM AND TYX, SHOWING LES IS COMING FROM A WNW
FLOW AND HAS SPREAD OUT MAINLY OVER ONEIDA, MADISON, AND ONONDAGA
COUNTIES. THERE MAY ALSO BE SOME LIGHT SNOW OVER OTSEGO COUNTY.
THESE SHOWERS SHOULD REMAIN LIGHT IN NATURE AND WILL GET LIGHTER
AS THE FLOW TURNS MORE NORTHERLY AND HIGH PRESSURE BUILDS IN.
LOOKING AT THE RADAR AND THE OBS, ANY HEAVIER SHOWERS, AND USING
THAT TERM LOOSELY, HAVE MOVED AWAY FROM THE LAKE SHORE. HOWEVER,
SOME ISOLATED SHOWERS MAY STILL DEVELOP NEAR THE LAKE SHORE AND
MOVE INTO THE CWA THROUGH THE MORNING HOURS. THE HRRR SHOWS MOST
OF THE ACTIVITY WELL TO THE SW OF THE CWA BY 20Z. OTHER MODELS
SHOW THEM DISSIPATING EVEN EARLIER. SO, TO SUM IT UP, FLURRIES TO
LIGHT SNOW SHOWERS POSSIBLE, MAINLY IN NEW YORK AND THE NORTHERN
TIER OF PA THROUGH MID AFTERNOON TO VERY EARLY EVENING. OTHERWISE,
CLOUDY BUT QUIET WEATHER TODAY.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH MONDAY NIGHT/...
HIGH PRESSURE WILL BUILD IN FOR THE REMAINDER OF THE WEEKEND AND
MONDAY. SUNDAYS TEMPS WILL BE NEAR NORMAL FOR THIS TIME OF YEAR.
THERE WILL BE A WARM UP ON MONDAY, WITH HIGHS REACHING INTO THE
LOW TO MID 40S. THIS IS AHEAD OF THE NEXT SYSTEM.
BY MONDAY AFTERNOON, A COLD FRONT, ASSOCIATED WITH A LOW PRESSURE
SYSTEM NEAR THE HUDSON BAY, WILL APPROACH THE AREA. MODELS ARE IN
PRETTY GOOD AGREEMENT, WITH THIS FRONT SLOWING AND STALLING MONDAY
NIGHT SOMEWHERE OVER THE CWA. THIS FRONT WILL BRING THE NEXT
CHANCE FOR RAIN AND SNOW SHOWERS TO THE AREA. MODELS ALSO
INDICATE, THAT THE PRECIPITATION SHOULD BE LIGHT AND THEN FIZZLE
OUT BY LATE MONDAY NIGHT/EARLY TUESDAY MORNING.
&&
.LONG TERM /TUESDAY THROUGH FRIDAY/...
LONG TERM IS DOMINATED OVERALL BY SOUTHWEST FLOW...WITH UNSETTLED
INTERRUPTION BY A COUPLE OF WAVES. NO MAJOR CONCERNS DISCERNIBLE
AT THIS TIME.
WEAKENING FRONT WILL SETTLE THROUGH THE AREA MONDAY NIGHT. GFS/ECWMF
BOTH SETTLE IT JUST SOUTH OF THE CWA TUESDAY...BEFORE RETURNING
NORTHWARD. HOWEVER...I ACCEPTED THE LOW CHANCE POPS OFFERED BY HPC
BECAUSE WITH FRONT BECOMING NEARLY FLOW-PARALLEL...IT MAY STRUGGLE
TO PUSH ALL THE WAY THROUGH AND COULD GET HUNG UP. ANY RESULTING
PRECIPITATION THOUGH WOULD BE VERY LIGHT.
ECMWF AND GFS ARE IN BETTER AGREEMENT ON AN UPPER LOW EJECTING OUT
OF THE SOUTHWEST U.S. AND OPENING UP WHILE GETTING ABSORBED INTO
THE WESTERLIES. WARM AIR ADVECTION AHEAD OF THE SYSTEM GETS
TEMPERATURES TO POINT WHERE PRECIPITATION SHOULD BE MAINLY RAIN...DURING
THE DAY WEDNESDAY...BUT UNCERTAINTY ON FRONT AND BACK ENDS FOR
PRECIPITATION TYPE. THOUGH NOT LIKELY...WINTRY MIX DURING THE
ONSET TUESDAY NIGHT IS NOT OUT OF THE QUESTION WITH ONLY SLIGHT
SHIFTS IN THE CURRENTLY PROJECTED TEMPERATURE PROFILES. THIS WILL
HAVE TO BE MONITORED. BECAUSE TIMING OF UPPER LOW EJECTION OUT OF
THE SOUTHWEST IS TYPICALLY SOMETHING THE MODELS STRUGGLE WITH...I
WENT AHEAD AND KEPT POPS IN CHANCE RANGE /40S-LOW 50S PCT/ TUESDAY
NIGHT AND WEDNESDAY UNTIL MORE MODEL RUNS CAN CONFIRM DETAILS
BETTER.
GFS/ECMWF DIVERGE AS WE HEAD LATE INTO THE WORKWEEK. BOTH REVERT TO
SOME SORT OF SOUTHWEST FLOW BUT ARE AT LEAST DAY OFF OF EACH
OTHER FOR WHEN TO SEND THE NEXT WAVE THROUGH THE FLOW. ECWMF HAS
WEAK AND DRY WAVE THURSDAY...GFS HAS A SLIGHTLY MORE AMPLIFIED
WAVE WAITING UNTIL FRIDAY...COMPLETE WITH GRADUALLY DEEPENING
SURFACE LOW OFF OF THE COAST. THE STRUGGLE APPEARS TO BE WHETHER
OR NOT THE SOUTHERN STREAM WAVE...CAN PHASE UP WITH A DIGGING
NORTHERN STREAM TROUGH. WITH SUCH UNCERTAINTY...KEEPING POPS IN
LINE WITH HPC...ONLY IN SLIGHT TO LOW CHANCE RANGE...PEAKING
FRIDAY.
&&
.AVIATION /09Z SATURDAY THROUGH WEDNESDAY/...
LE SNOWS WILL CAUSE SOME IFR CIGS AND VSBYS AT TIMES AT RME AND
SYR OVRNGT...AND PSBL MVFR AT ITH AND BGM. IN GNRL...LE WILL
WEAKEN AS THE FLOW CONTS TO BECOME MORE NWLY BHD THE SFC TROF.
SOME LEFTOVER LGT LE SNOW SHWRS AFT DAYBRK SAT...OTRW VFR CONDS
UNDER HIPRES WILL HOLD THUR THE REST OF THE TAF PD.
.OUTLOOK...
SAT NGT THRU MON NGT...MAINLY VFR.
TUE/WED...POSSIBLE MVFR/IFR...ESPECIALLY TUE NGT AND WED AS SYSTEM
COMES THROUGH.
&&
.BGM WATCHES/WARNINGS/ADVISORIES...
PA...NONE.
NY...NONE.
&&
$$
SYNOPSIS...SLI
NEAR TERM...SLI
SHORT TERM...SLI
LONG TERM...MDP
AVIATION...DGM/MDP
AREA FORECAST DISCUSSION
NWS WILMINGTON NC
1246 AM EST SAT DEC 17 2011
.SYNOPSIS...
A COLD FRONT WILL MOVE THROUGH THE AREA OVERNIGHT...BRINGING ONLY A
SMALL CHANCE OF LIGHT RAIN. MUCH COLDER AIR WILL MOVE IN FOR THE
WEEKEND AS ARCTIC HIGH PRESSURE APPROACHES FROM THE WEST.
TEMPERATURES WILL RETURN TO ABOVE NORMAL LEVELS NEXT WEEK AS THE
HIGH MOVES OFFSHORE LATE MONDAY AND TUESDAY. ANOTHER COLD FRONT
WILL MOVE INTO THE AREA ON WEDNESDAY AND MAY STALL. RAIN CHANCES
WILL INCREASE DURING THE LATTER PORTION OF NEXT WEEK.
&&
.NEAR TERM /THROUGH TONIGHT/...
AS OF 12:30 AM SATURDAY...COLD FRONT HAS MOVED THROUGH OUR NC
COUNTIES AND SHOULD CLEAR THE CWA BY DAWN. SHIELD OF LIGHT PRECIP
PASSING TO OUR NORTH AND LOOKS UNLIKELY WE WILL SEE ANY
ACCUMULATIONS FROM THIS. UPDATE FORECAST ACCORDINGLY. RELEVANT
PORTIONS OF PREVIOUS DISCUSSION FOLLOWS:
RAIN CHANCES ARE THE BIGGEST FORECAST CONCERN OVERNIGHT. CURRENT
RADAR COMPOSITES SHOW A RATHER EXPANSIVE AREA OF LIGHT RAIN
EXTENDING FROM THE CHARLOTTE METRO AREA INTO NORTHEASTERN NORTH
CAROLINA. VERY LITTLE RAIN EXTENDS SOUTH OF THIS BATCH TO IMPACT
OUR FORECAST AREA OVERNIGHT. SHALLOW LIFT OVER THE FRONTAL SURFACE
WITHIN A ZONE OF MOISTURE EXTENDING UP TO 775 MB COULD CAUSE SOME
PATCHES OF LIGHT RAIN TO DEVELOP AS FAR SOUTH AS FLORENCE...
MARION...CONWAY...AND SOUTHPORT...ALTHOUGH THE CHANCES OF
RECEIVING A MEASURABLE 0.01" IS PRETTY SLIM. WE WILL MAINTAIN A 20
(SLIGHT CHANCE) POP FOR THE AFOREMENTIONED AREAS...WITH SOME OF
THE LATEST HRRR RUNS STILL SHOWING VERY LIGHT PRECIPITATION
DEVELOPING AFTER 06Z ACROSS SOUTHEASTERN NORTH CAROLINA AND
ADJACENT PORTIONS OF SOUTH CAROLINA.
AS THE FRONT PASSES BY OVERNIGHT TEMPERATURES WILL FALL INTO THE MID
TO UPPER 40S ACROSS INTERIOR SECTIONS OF THE CAROLINAS...WITH TEMPS
~5 DEGREES WARMER AT THE IMMEDIATE COAST DUE TO SOME WEAK MARINE
INFLUENCE ON THE NORTH-NORTHEAST POST-FRONTAL WIND. AHEAD OF THE
FRONT CURRENT (9 PM) TEMPERATURES RANGE FROM THE MID TO UPPER 50S
WHERE SKIES ARE CLEAR...TO THE LOWER 60S WHERE SKIES ARE CURRENTLY
CLOUDY.
&&
.SHORT TERM /SUNDAY THROUGH SUNDAY NIGHT/...
AS OF 230 PM FRIDAY...A SURFACE COLD FRONT WILL BE SOUTH OF THE
SOUTH SANTEE RIVER SAT MORNING AND WILL CONTINUE TO MOVE TO THE
SOUTH. AN UPPER TROUGH WILL BOTTOM OUT ACROSS THE EAST COAST SAT
AND SAT NIGHT. THIS TROUGH WILL BE VERY PROGRESSIVE...MOVING
OFFSHORE DURING SUN. UPPER RIDGE WILL THEN BUILD ACROSS THE AREA
SUN NIGHT AND MON. FORECAST PERIOD WILL START WITH BKN TO OVC LOW
CLOUDS AND PERHAPS SOME SPRINKLES AS LOW LEVEL MOISTURE REMAINS
LOCKED BENEATH A FRONTAL INVERSION. A SHORTWAVE TROUGH WILL MOVE
ACROSS THE AREA SAT AFTERNOON AND EVE AND THIS WILL SCOUR OUT
REMAINING LOW LEVEL MOISTURE.
CLOUDINESS WILL EVENTUALLY ERODE DURING SAT WITH SKIES CLEAR OR
CLEARING BY EVE. H8 TEMPS WILL DROP FROM AROUND 7 DEG C TO 3 DEG C
SAT. H8 TEMPS WILL BOTTOM OUT AROUND ZERO DEG C ON SUN. THIS INFLUX
OF COLD AIR WILL DELAY ANY SIGNIFICANT UPWARD TREND IN TEMPS SAT.
TEMPS SHOULD STILL BE DROPPING SAT MORNING...BUT AFTERNOON TEMPS
SHOULD BE ABLE TO RECOVER TO THE MID 50S MOST PLACES AND CLOSER TO
60 DEG AS YOU NEAR THE SOUTH SANTEE RIVER. AS SURFACE HIGH
PRESSURE...CENTERED ACROSS THE MID SOUTH AND GULF COAST GROWS
CLOSER...WINDS SHOULD FULLY DECOUPLE DURING SAT NIGHT. CLEAR SKIES
AND LIGHT N WINDS SHOULD ALLOW RADIATIONAL COOLING TO GAIN A STRONG
FOOT HOLD OVERNIGHT. READINGS SUN MORNING WILL BE IN THE LOWER TO
MID 30S WITH SOME OF OUR NORMALLY COLD SPOTS DROPPING INTO THE UPPER
20S. BRIGHT SUNSHINE ON SUN WILL ONLY BE ABLE TO PROPEL TEMPS INTO
THE MID AND UPPER 50S. SUN NIGHT SHOULD BE COLDER THAN THE PREVIOUS
NIGHT. HIGH PRESSURE WILL BE CENTERED VIRTUALLY OVERHEAD SUN NIGHT
WITH SOME THIN CIRRUS INCREASING LATE. TEMPS MON MORNING WILL BE IN
THE UPPER 20S TO LOWER 30S WITH SOME MID 20S IN THE COLDEST
LOCATIONS.
&&
.LONG TERM /MONDAY THROUGH FRIDAY/...
AS OF 230 PM FRIDAY...THE EXTENDED FORECAST WARRANTS FEW CHANGES
THIS AFTERNOON AS MOST OF THE ACTION WILL BE CONCENTRATED ON THE
MIDDLE AND LATTER PART OF THE PERIOD. A WEAKENING SHORTWAVE WILL
MOVE ACROSS THE MISSISSIPPI VALLEY LATE TUESDAY AND WEDNESDAY WITH
A WEAK FRONT MOVING ACROSS THE SOUTH. AS HAS BEEN THE CASE THE
PAST FEW WEEKS...THE BEST FORCING WITH THIS SYSTEM MOVES OFF TO
THE NORTHEAST. TWEAKED THE TIMING WITH THE LATEST FORECAST TO
DELAY THE TIMING OTHERWISE I MAINTAINED THE CHANCE POPS FOR LATE
TUESDAY INTO WEDNESDAY FOR OUR AREA. ANOTHER SYSTEM IN THE
SOUTHERN BRANCH QUICKLY FOLLOWS FOR LATE THURSDAY INTO FRIDAY WITH
A BRIEF REPRIEVE EARLY THURSDAY. TEMPERATURES LOOK TO REMAIN ABOVE
NORMAL WITH THE EXCEPTION OF MONDAY WHEN HIGH PRESSURE WILL BE
ESSENTIALLY OVERHEAD.
&&
.AVIATION /06Z SATURDAY THROUGH WEDNESDAY/...
AS OF 06Z...MODERATE CONFIDENCE OVERNIGHT AS COLD FRONT BRINGS A
CHANCE OF SOME VERY LIGHT RAIN AND MVFR. VFR WILL DEVELOP SATURDAY
AFTN.
COLD FRONT HAS PASSED THROUGH ALL TERMINALS EXCEPT THE MYRTLES...AND
THIS WILL OCCUR SHORTLY THERE AS WELL. RAIN HAS HAD A VERY DIFFICULT
TIME MAKING ANY SE PROGRESS BEHIND THE FRONT. AM CONFIDENT IN
MVFR CIGS. UPSTREAM OBS SHOW WIDESPREAD POST-FRONTAL MVFR
STRATUS...AND EXPECT THIS SO SLOWLY ADVECT SE WITH THE FRONT.
QUESTION AS TO WHETHER CIGS WILL LOWER TO IFR STILL EXISTS...BUT
MOST GUIDANCE HAS BACKED OFF ON THIS POTENTIAL. STILL SEEING IFR
ONLY OCCURRING WHERE SIGNIFICANT RAIN HAS FALLEN...WHICH WILL NOT
OCCUR EVEN AT LBT...SO HAVE CONTINUED WITH MVFR AS THE WORST
RESTRICTION AND WILL MONITOR AS NECESSARY. CANNOT RULE SOME OUT
IFR AT LBT OVERNIGHT.
S/W WILL PUSH OFF TO THE EAST EARLY SATURDAY BRINGING DRIER AIR TO
THE REGION. THIS WILL HELP ERODE CLOUD COVER AND VFR WILL DEVELOP BY
LATE MORNING OR EARLY AFTN. WINDS WILL PERSIST FROM THE NORTH
THROUGH SATURDAY AROUND 10 KTS. SKY CONDITIONS WILL IMPROVE TO SKC
WHILE WINDS DROP TO NEAR CALM AFTER NIGHTFALL.
EXTENDED OUTLOOK...VFR SUNDAY AND MONDAY. MORNING FOG POSSIBLE
TUESDAY. SHOWERS ASSOCIATED WITH A COLD FRONT MAY IMPACT THE AREA
WEDNESDAY.
&&
.MARINE...
NEAR TERM /THROUGH TONIGHT/...
AS OF 12:30 AM SATURDAY...COLD FRONT PASSING FROM NORTH TO SOUTH
ACROSS OUR NC WATERS WITH WINDS SHIFTING TO W AND THEN NW. EXPECT
FRONT TO CLEAR OUR SOUTHERN WATERS BY DAWN. CURRENT BUOY OBS SHOW
2 TO 4 FT SEAS OVER THE COASTAL WATERS...WHICH IS AS FORECAST.
PREVIOUS DISCUSSION FOLLOWS:
A COLD FRONT ACROSS EASTERN NORTH CAROLINA HAS MOVED THROUGH
MOREHEAD CITY AND JACKSONVILLE...AND WILL BE IN SURF CITY WITHIN
THE NEXT HOUR. THIS FRONT SHOULD CONTINUE MOVING SOUTH
TONIGHT...MOVING ACROSS CAPE FEAR BETWEEN MIDNIGHT AND 2
AM...MYRTLE BEACH BETWEEN 1-3 AM...AND THROUGH GEORGETOWN AN HOUR
OR TWO BEFORE DAYBREAK SATURDAY. SOUTHWEST WINDS WILL TURN
WESTERLY AHEAD OF THE FRONT LATER THIS EVENING...THEN WILL
ABRUPTLY SHIFT TO THE NORTH BEHIND THE FRONT. WITH QUICKLY FALLING
TEMPERATURES BEHIND THE FRONT WINDS WILL BECOME GUSTY WITH GUSTS
OVER 20 KNOTS POSSIBLE FOR A FEW HOURS. ANY LIGHT RAIN ASSOCIATED
WITH THE FRONT SHOULD REMAIN MAINLY NORTH OF CAPE FEAR...BUT THE
LATEST MODEL PROJECTIONS ARE THAT VERY LITTLE RAIN WILL FALL EVEN
HERE.
SEAS RANGE FROM 2.5 TO 4 FT AT THE BUOYS THIS EVENING...AND THE
SPECTRAL WAVE PLOT FROM FRYING PAN SHOALS SHOWS THE WAVES ARE ALMOST
EXCLUSIVELY AN 11-14 SECOND SOUTHEAST SWELL. VERY LITTLE WIND CHOP
EXISTS ACROSS THE WATERS CURRENTLY...BUT THIS SHOULD CHANGE LATE
TONIGHT BEHIND THE FRONT WITH THE INCREASING COLD NORTHERLY WINDS.
SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/...
AS OF 230 PM FRIDAY...A MODEST NORTHERLY SURGE WILL BE UNDERWAY
AT THE START OF THE PERIOD. INITIAL SURGE WILL WANE SAT AFTERNOON
WITH ANOTHER SURGE EXPECTED SAT NIGHT AND THEN AGAIN DURING SUN. N
WINDS WILL VEER TO NE SUN NIGHT AS WINDS DIMINISH. WINDS WILL
REMAIN BELOW SMALL CRAFT ADVISORY LEVELS THROUGH THE WEEKEND. SEAS
SHOULD PEAK IN 3 TO 5 FT RANGE ACROSS THE WATERS OFF OF CAPE FEAR
DURING SAT AND 3 TO 4 FT ACROSS THE OUTER FRINGES OF THE SOUTHERN
WATERS. SIX FT SEAS ARE POSSIBLE AROUND FRYING PAN SHOALS BUOY ON
SAT. SUBSEQUENT SURGES ARE NOT EXPECTED TO PRODUCE WAVE HEIGHTS
ECLIPSING THESE VALUES.
LONG TERM /MONDAY THROUGH WEDNESDAY/...
AS OF 230 PM FRIDAY...LIGHT WINDS WILL GREET MARINERS MONDAY AS
HIGH PRESSURE RESIDES OVERHEAD. A SOUTHERLY FLOW WILL DEVELOP
LATER MONDAY AND PREVAIL TUESDAY AS THE HIGH MOVES OFFSHORE. WINDS
WILL TURN MORE TO THE SOUTHWEST WEDNESDAY AS LOW PRESSURE MOVES
THROUGH THE OHIO VALLEY. THIS STRONGEST WINDS WILL PREVAIL
WEDNESDAY AS WELL WITH 20-25 KNOTS. WAVEWATCH SEAS LOOK REASONABLE
WITH 2-4 FEET EARLY INCREASING TO 4-6 FEET WEDNESDAY. FINALLY
THERE IS THE POSSIBILITY FOR SEA FOG TUESDAY BEFORE WINDS TURN
MORE SOUTHWEST.
&&
.ILM WATCHES/WARNINGS/ADVISORIES...
SC...NONE.
NC...NONE.
MARINE...NONE.
&&
$$
NEAR TERM...REK
AVIATION...JDW/REK
AREA FORECAST DISCUSSION...UPDATED
NWS FORT WORTH TX
614 PM CST SUN DEC 18 2011
.AVIATION...
CONCERNS...MVFR CEILINGS DEVELOPING 09-12Z. POSSIBLE
THUNDERSTORMS MONDAY AFTERNOON/EVENING.
AN UPPER LEVEL LOW CURRENTLY OVER SOUTHWESTERN ARIZONA...WILL
MOVE EAST ACROSS THE SOUTHERN PLAINS IN THE NEXT 24 TO 36 HOURS.
INCREASING SOUTHERLY LOW LEVEL FLOW WILL BRING SOME MVFR CEILINGS
NORTHWARD INTO WACO AROUND 09Z...AND INTO THE METROPLEX AROUND
12Z. MVFR CEILINGS SHOULD THEN HOLD IN FOR MOST...IF NOT...ALL OF
THE DAY. A LINE OF THUNDERSTORMS IS EXPECTED TO DEVELOP ACROSS
WEST TEXAS BY MIDDAY MONDAY AND MOVE EAST ACROSS NORTH TEXAS
DURING THE AFTERNOON AND EVENING HOURS. FOR NOW HAVE PLACED 6SM
-TSRA STARTING AT 21Z AT ALL OF THE TAF SITES...THOUGH SOME
EARLIER ACTIVITY MAY OCCUR AHEAD OF THE MAIN LINE OF
THUNDERSTORMS. WINDS SHOULD SHIFT TO SOUTHWEST AFTER 03Z.
58
&&
.PREV DISCUSSION... /ISSUED 407 PM CST SUN DEC 18 2011/
12Z UPPER AIR ANALYSIS INDICATED THAT A CUT OFF LOW REMAINED IN
PLACE OVER FAR SOUTHERN CA WITH RIDGING OVER THE GULF OF MEXICO.
THIS LEFT SOUTHWEST FLOW ALOFT OVER THE SOUTHERN PLAINS OUT AHEAD
OF THE UPPER LOW. SOUTHWEST FLOW ALOFT HAD LED TO THE ADVECTION OF
STEEP LAPSE RATES INTO WEST TX THIS MORNING WITH A TEMPERATURE
DIFFERENCE IN THE H700 TO H500 LAYER OF 22 DEG C. A POOL OF 10 DEG
C DEW POINTS WAS OBSERVED AT THE H850 LEVEL OVER FAR SOUTH TX AND
THE EFFECTS OF LEE SIDE CYCLOGENESIS WERE BECOMING EVIDENT WITH
THE DEVELOPMENT OF A CYCLONIC CIRCULATION OVER FAR WEST TX. 21Z
SFC ANALYSIS INDICATED THAT A MOISTURE WAS RAPIDLY RETURNING TO
WESTERN AND CENTRAL TX WITH 45 DEG F DEW POINTS OBSERVED AS VAR
NORTH AS CHILDRESS.
TONIGHT THROUGH TUESDAY...AFTERNOON WATER VAPOR IMAGERY INDICATED
THAT THE CUT OFF LOW AS ALREADY BEGINNING TO MOVE EAST AND THE
CENTER OF CIRCULATION HAD JUST CROSSED OVER THE SOUTHERN AZ BORDER
AS OF 21Z. A PLUME OF PACIFIC MOISTURE HAS ALREADY BEEN ADVECTED
OVER MUCH OF THE SOUTHERN PLAINS...AND SOUTHWEST FLOW ALOFT
CONTINUES THIS TRANSPORT OF MID TO UPPER TROPOSPHERIC MOISTURE
INTO THE REGION. THE PROGRESSION OF SURFACE DEW POINTS WAS THE
MOST INTERESTING PIECE OF INFORMATION THAT COULD BE OBSERVED ABOUT
THE POTENTIAL THERMODYNAMIC ENVIRONMENT THIS AFTERNOON AHEAD OF
THIS UPPER LOW. BASED ON 12Z GUIDANCE...THE NAM WAS THE ONLY MODEL
TO SUFFICIENTLY HANDLE THE RAPID INFLUX OF LOW LEVEL MOISTURE INTO
TX. THE NAM HAD ROUGHLY AN ACCURATE REPRESENTATION OF 21Z DEW
POINTS ACROSS TX WITH THE GFS LAGGING BEHIND BY 6 HRS AND THE
ECMWF COMING IN A FEW DEG F TOO LOW FOR ITS 00Z FORECAST THIS
EVENING. EVEN THE 18Z INITIALIZATION OF THE RUC IS SLOW ON THIS
MOISTURE TRANSPORT WHICH POINTS TO A POTENTIALLY SIGNIFICANT
SOURCE OF ERROR WITH REGARDS TO HANDLING THE THERMODYNAMIC
ENVIRONMENT THAT WILL SET UP OVER NORTH TX TOMORROW.
DID NOT CHANGE MUCH WITH REGARDS TO THE TIMING OF EXPECTED
PRECIPITATION ACROSS NORTH TX WITH THIS FORECAST PACKAGE. THE
UPPER LEVEL SYSTEM AND ASSOCIATED FRONTAL BOUNDARIES ARE EXPECTED
TO MOVE THRU NORTH TX AT ROUGHLY THE SAME TIME AS THE PREVIOUS
FORECAST INDICATED. THE UPPER LOW IS EXPECTED TO MOVE INTO THE
SOUTHERN PLAINS TOMORROW EVENING AND THEN BECOME NEGATIVELY TILTED
AS IT MOVES NORTHEAST OVER NORTH CENTRAL TX AND OVER OK MONDAY
NIGHT. STRONG LARGE SCALE FORCING FOR ASCENT WILL SPREAD OVER
NORTH TX AHEAD OF THIS UPPER LOW...WITH MAXIMUM ASCENT SPREADING
OVER THE FORECAST AREA FROM 21Z MONDAY TO 06Z TUESDAY. THE
FORECAST STRENGTH OF THE UPPER LOW AS IT MOVES OVER THE SOUTHERN
PLAINS IS HIGH WITH H500 HEIGHTS REGISTERING AS A -2.5 STANDARD
DEVIATION ANOMALY PER HPCS ANALYSIS OF THE 12Z GFS. PRECIPITABLE
WATER VALUES CONTINUE TO BE FORECAST TO HOLD IN THE 99TH
PERCENTILE OVER NORTH TX FOR DECEMBER. THE 0 TO 6 KM BULK SHEAR
MAGNITUDE IS EXPECTED TO BE IN EXCESS OF 55 KTS DURING THE PERIOD
OF MAXIMUM FORCING FOR ASCENT WHICH SPEAKS TO THE STRENGTH OF THE
WIND FIELDS OUT AHEAD OF THIS SYSTEM. INSTABILITY CONTINUES TO BE
THE MOST DIFFICULT PARAMETER TO FORECAST...AND THE DEGREE OF
INSTABILITY WILL LARGELY DETERMINE OUR SEVERE WEATHER CHANCES AND
COVERAGE TOMORROW AFTERNOON.
BASED ON 21Z SURFACE OBS...THE NAM APPEARS TO HAVE THE BEST HANDLE
ON LOW LEVEL MOISTURE MOISTURE RETURN OUT AHEAD OF THIS SYSTEM.
MOISTURE TRANSPORT IS EXPECTED TO INCREASE IN INTENSITY TONIGHT
AND DURING THE DAY MONDAY AS THE UPPER LEVEL LOW MOVES OVER THE
SOUTHERN PLAINS. THE LOW LEVEL JET IS FORECAST TO INCREASE TO AT
LEAST 50 KTS OVER NORTH TX TOMORROW...WITH OUR LOCAL 4 KM WRF
INDICATING A POTENTIAL JET CORE OF 60 KTS AFTER 21Z. STRATUS IS
STILL EXPECTED TO BE IN PLACE OVER MOST OF THE OPEN WARM SECTOR
TOMORROW WHICH WILL BE A LIMITING FACTOR FOR LOW LEVEL
DESTABILIZATION. HOWEVER WITH MOISTURE TRANSPORT LIKELY
UNDERESTIMATED IN MOST OPERATIONAL GUIDANCE...THINK THAT SURFACE
BASED INSTABILITY IS LIKEWISE UNDERESTIMATED. 12Z MOS GUIDANCE IS
NOW CONSISTENT WITH MID 60S HIGHS FOR DFW TOMORROW. MOS GUIDANCE
ALSO INDICATES HIGHS IN THE UPPER 60S TO LOWER 70S FOR WACO
TOMORROW. THIS IS A FEW DEGREES WARMER THAN HIGHS WERE EXPECTED TO
CLIMB FROM YESTERDAYS FORECAST.
CONFIDENCE IN THESE HIGHER TEMPERATURES IS INCREASING DUE TO
SIGNIFICANT BREAKS IN CLOUD COVER OVER NORTH TX AND THE TX GULF
COAST. WARMER AFTERNOON TEMPERATURES TODAY WILL THEORETICALLY LEAD
TO WARMER OVERNIGHT LOWS ONCE CLOUD COVER BUILDS BACK IN TONIGHT.
THIS WOULD MEAN THAT LESS HEATING IS NECESSARY TO REACH HIGHER
TEMPERATURES TOMORROW AFTERNOON. THE 12 AND 18Z NAM RUNS BOTH
CONTINUE TO AGGRESSIVELY ADVERTISE FREE CONVECTION POTENTIAL
TOMORROW AFTERNOON AND EVENING. WITH THE NAM HAVING THE BEST
HANDLE ON LOW LEVEL MOISTURE AND HIGH TEMPERATURES LIKELY CLIMBING
A FEW DEGREES HIGHER TOMORROW THAN PREVIOUS EXPECTED...CONFIDENCE
IN THE NAMS THERMODYNAMIC SOLUTION HAS INCREASED SUBSTANTIALLY.
THE NAM ADVERTISES A CORRIDOR OF SURFACE BASED CAPE OF 1000 J/KG
EXTENDING FROM THE METROPLEX SOUTH...NEAR THE INTERSTATE 35
CORRIDOR BY 00Z TUE OR TOMORROW AT 6 PM.
AS PREVIOUS FORECAST MENTIONED...LOW LCL HEIGHTS INDICATE THAT A
SIGNIFICANT PORTION OF THE FREE CONVECTION POTENTIAL ENERGY /CAPE/
WILL LIE IN THE LOWEST 3 KMS. 0 TO 3 KM CAPE VALUES ARE FORECAST
TO BE IN EXCESS OF 200 J/KG WITHIN THIS SAME GENERAL CORRIDOR.
THESE VALUES ARE QUITE HIGH EVEN FOR A SPRING SEVERE WEATHER
EPISODE...AND HIGH LOW LEVEL CAPE VALUES SPEAK TO THE POTENTIAL
FOR LOW LEVEL STRETCHING AND TILTING OF HORIZONTAL VORTICITY INTO
THE VERTICAL. LOW LEVEL WIND PROFILES CONTINUE TO VEER WITH HEIGHT
AND CONTAIN SIGNIFICANT SPEED SHEAR DUE TO THE PRESENCE OF THE
STRONG LOW LEVEL JET. 0-1 KM HELICITY VALUES IN EXCESS OF 200
M2/S2 ARE PRESENT WITHIN THE CORRIDOR OF HIGH LOW LEVEL CAPE. THIS
COMBINATION OF PARAMETERS INDICATES THAT ANY UPDRAFT WILL HAVE A
STRONG LIKELIHOOD TO INGEST HORIZONTAL VORTICITY WHICH GREATLY
INCREASES THE SEVERE WEATHER THREAT TOMORROW AFTERNOON. THE
GENERAL STORM MODE IS STILL EXPECTED TO BE LINEAR WITH SIGNIFICANT
FORCING FOR ASCENT EXPECTED ALONG A PACIFIC TYPE COLD FRONT THAT
WILL MOVE TROUGH NORTH TX JUST AHEAD OF THE CORE OF THE UPPER LOW.
THIS NORTH/SOUTH ORIENTED FRONT IS ORIENTED NEARLY PARALLEL TO THE
0-6 KM BULK SHEAR VECTORS WHICH GENERALLY FAVORS SHARED COLD POOLS
LEADING TO A LINEAR STORM MODE.
EVEN WITH A LINEAR STORM MODE STRETCHING AND TILTING OF HORIZONTAL
VORTICITY INTO THE VERTICAL CAN LEAD TO THE DEVELOPMENT OF
MESOVORTICIES CAPABLE OF PRODUCING STRONG LOCALIZED WIND
DAMAGE...AND TO THE DEVELOPMENT OF BRIEF TORNADOES. ANY DISCRETE
STORMS OUT AHEAD OF LINE SEGMENT CONVECTION WILL LIKELY BE IN THE
FORM OF LOW-TOPPED AND VERY FAST MOVING SUPERCELLS. ANY LOW-TOPPED
SUPERCELL AWAY FROM THE MAIN LINE OF CONVECTION WILL BE CAPABLE OF
PRODUCING A TORNADO...ESPECIALLY SOUTH OF THE METROPLEX TOMORROW
AFTERNOON. THE MOST WIDESPREAD SEVERE WEATHER HAZARD IS THOUGHT
TO BE IN THE FORM OF STRAIGHT LINE WIND DAMAGE...AND THIS IS
MOSTLY DUE TO THE POTENTIAL FOR STRONG ENVIRONMENTAL WINDS TO BE
DRIVEN DOWN TO THE SURFACE. DEEP MOISTURE MEANS THAT THERE IS
LITTLE THETA-E DIFFERENCE WITH HEIGHT...AND THEREFORE LITTLE
POTENTIAL FOR ENHANCED DOWNDRAFT SPEEDS OR MICROBURSTS.
OVERALL CONFIDENCE IN AN ORGANIZED STORM MODE IS HIGH NOW FOR
TOMORROW AFTERNOON. DAMAGING STRAIGHT LINE WINDS WITH A HIGH
POTENTIAL FOR LOCALLY ENHANCED DAMAGE IS THE MOST PREVALENT SEVERE
WEATHER HAZARD. THERE IS AN ATTENDANT TORNADO THREAT TOMORROW
AFTERNOON...ESPECIALLY IF ANY DISCRETE STORMS ARE ABLE TO DEVELOP
OUT AHEAD OF THE SQUALL LINE/PACIFIC FRONT. 99TH PERCENTILE PWATS
ALWAYS RAISE THE POTENTIAL FOR LOCALIZED FLOODING ISSUES...HOWEVER
THE VERY FAST STORM MOTION IS EXPECTED TO MITIGATE SIGNIFICANT
FLOODING CONCERNS.
THE PACIFIC TYPE COLD FRONT IS EXPECTED TO MOVE EAST THRU MOST OF
NORTH TX BY MIDNIGHT /06Z TUE/ MONDAY NIGHT. THE ATTENDANT SQUALL
LINE WILL LIKELY BE JUST EXITING THE FORECAST AREA AT THIS TIME
SO HAVE LINGERED HIGH POPS OVER THE FAR EASTERN CWA AFTER
MIDNIGHT. BY TUESDAY MORNING THERE IS SOME LOW END POTENTIAL FOR
LIGHT RAIN ASSOCIATED WITH MOISTURE WRAPPED AROUND THE UPPER
LOW...ESPECIALLY AS SOME RESIDUAL FRONTOGENETIC FORCING BUILDS
INTO THE NORTHERN CWA AS THE CANADIAN AIRMASS RESPONSIBLE FOR THE
BLIZZARD PORTION OF THIS SYSTEM /OVER THE SOUTHERN HIGH PLAINS/
MOVES SOUTH INTO NORTH TX. NO WINTRY PRECIPITATION IS EXPECTED AT
THIS TIME AS THERE WILL BE VERY LITTLE MOISTURE LEFT TO WORK WITH
AND TEMPERATURES WILL GENERALLY REMAIN ABOVE FREEZING EARLY
TUESDAY MORNING BEHIND THE FRONT.
EXTENDED...NO SIGNIFICANT CHANGES MADE TO THE EXTENDED AT THIS
TIME. KEPT THE LOW END RAIN CHANCES OVER THE SOUTHEASTERN PORTION
OF THE CWA ON THURSDAY AS ANOTHER SHORTWAVE TROUGH MOVES OVER
NORTH TX. THE 12Z ECMWF WAS THE MOST AGGRESSIVE WITH PRECIPITATION
BECAUSE IT BRINGS THE WAVE OVER NORTH TX THE FURTHEST NORTH AND
STRONGER THAN THE GFS ADVERTISES. EITHER WAY LIMITED MOISTURE WILL
PREVENT SIGNIFICANT COVERAGE OF RAIN OVER NORTH TX ON THURSDAY.
MAINTAINED A DRY FORECAST FOR THE HOLIDAY WEEKEND AS RUN TO RUN
AND MODEL TO MODEL CONSISTENCY EVEN ON LARGE SCALE FLOW REMAINS
POOR AT THIS TIME. GENERAL CONSENSUS IS THAT TEMPERATURES WILL BE
BELOW NORMAL...SO FOR NOW A COOL AND DRY HOLIDAY WEEKEND IS
EXPECTED.
CAVANAUGH
&&
.PRELIMINARY POINT TEMPS/POPS...
DALLAS-FT. WORTH, TX 51 64 45 50 31 / 10 80 100 5 5
WACO, TX 52 67 44 53 28 / 10 70 100 5 5
PARIS, TX 44 63 47 54 30 / 10 50 100 10 10
DENTON, TX 52 61 43 46 27 / 10 90 100 10 5
MCKINNEY, TX 48 62 45 50 30 / 10 80 100 5 5
DALLAS, TX 51 64 46 50 31 / 10 80 100 5 5
TERRELL, TX 48 64 49 53 31 / 10 50 100 5 5
CORSICANA, TX 48 66 47 55 32 / 10 50 100 5 5
TEMPLE, TX 50 66 43 55 29 / 10 70 100 5 5
MINERAL WELLS, TX 53 64 39 46 25 / 20 100 80 10 5
&&
.FWD WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
58/30
FOR FREQUENTLY ASKED QUESTIONS ABOUT THE AREA FORECAST DISCUSSION VISIT...
HTTP://WEATHER.GOV/SALTLAKECITY/GENERAL/AFD_FAQS.PHP (ALL LOWER CASE)
AREA FORECAST DISCUSSION
NWS MILWAUKEE/SULLIVAN WI
916 PM CST SUN DEC 18 2011
.UPDATE...
A FEW THINGS TO ADJUST...GRADIENT IS KEEPING WINDS UP HIGHER THAN
EXPECTED AND ADVECTING WARMER TEMPERATURES INTO SRN WI. HAVE UPPED
TEMPERATURES FOR THE EVENING THROUGH ABOUT 05Z TO 06Z...THEN BEGIN A
SLOW FALL WITH LOWER WINDS AND BAGGY GRADIENT AS SURFACE TROUGH
PASSES THROUGH BETWEEN 09Z AND 12Z. CLOUDS WITH 4K TO 6K FT
BASES...LIFTING UP FROM NE IA/NW IL ARE ASSOCIATED WITH HIGHER
DEW POINT AIR ALONG REGION OF SPEED CONVERGENCE ON BACK EDGE OF
TIGHTER SFC PRESSURE GRADIENT AHEAD OF SFC TROUGH. LOW CLOUDS WELL
OFF TO THE NW ACROSS NRN MN INTO N DAKOTA ALONG AND BEHIND COLD
FRONT. MAY GET A PERIOD OF CLOUDS ON OVER FAR SRN WI ON NORTH END
OF THE IA/IL CLOUD DECK...THEN MOSTLY CLEAR UNTIL COLD FRONT DROPS
THROUGH LATER MONDAY MORNING.
&&
.AVIATION/06Z TAFS/...
HAVE PUSHED BACK START TIME TO POTENTIAL MVFR CIGS/VSBYS AS
GRADIENT HAS KEPT SURFACE WINDS UP AND MIXING PREVENTING ANY LOW
STRATUS OR FOG TO FORM. WINDS WILL DROP OFF AS SURFACE TROUGH
CROSSES SRN WI FROM WEST TO EAST BETWEEN 09Z AND 12Z. RUC SHOWS
SFC TO 950 MB LAYER MOISTENING AS WINDS DIE OFF...BUT LEANING
TOWARDS KEEPING VFR CONDITIONS AT ALL TAF SITES IN 06Z TAF ISSUANCE
UNTIL MID-MORNING MONDAY WHEN LOW CLOUDS MOVE IN WITH COLD FRONT.
WILL ASSESS LATEST GUIDANCE AND TRENDS AND MAY ISSUE EARLIER
UPDATES IF NOTHING DEVELOPS IN THE NEXT HOUR OR SO.
.MARINE...
WILL KEEP SMALL CRAFT GOING UNTIL 8 AM MONDAY. GUSTS STILL
REACHING CRITERIA AT SHORELINE SITES AND EVEN HIGHER WITH A FEW
SHIP OBS OFFSHORE. WINDS MAY DIMINISH BEFORE 8 AM...BUT WITH SFC
TROUGH NOT CLEARING THE EAST UNTIL BETWEEN 6 AM AND 8 AM...WILL
NOT MAKE ANY ADJUSTMENTS AT THIS TIME.
NEW NAM STILL SHOWS NORTH TO NORTHEAST WINDS APPROACHING SMALL CRAFT
LEVELS MONDAY AFTERNOON AND INTO THE EVENING BEHIND THE FRONT...WITH
WAVES TOWARD ILLINOIS POSSIBLY EXCEEDING 4 FEET MONDAY NIGHT. THIS
TIME WILL HAVE TO BE WATCHED FOR ANOTHER POSSIBLE SMALL CRAFT
ADVISORY.
&&
.PREV DISCUSSION... /ISSUED 329 PM CST SUN DEC 18 2011/
VERY SHORT TERM...TONIGHT AND MONDAY.
MOSTLY CLEAR SKIES WILL PERSIST INTO THE EVENING. WARM AIR ADVECTION
ALOFT WILL CONTINUE THROUGH THE NIGHT. MODELS ALL SATURATE IN THE
LOWER LEVELS UNDER THE INVERSION TOWARD MIDNIGHT OR SHORTLY
THEREAFTER...SUGGESTING THE FORMATION OF STRATUS. CLOUDS AND WARM
ADVECTION WILL LIKELY KEEP TEMPERATURES FROM FALLING OUT OF THE 30S
MOST PLACES.
A WEAK SURFACE FRONT WILL DROP THROUGH SOUTHERN WISCONSIN EARLY
MONDAY MORNING...BUT NOT MUCH FORCING OR DEEP SATURATION TO CONSIDER
PRECIP. LOW CLOUDS WILL LIKELY THEN LINGER TROUGH MUCH OF DAY. NOT A
BIG PUSH OF COLDER AIR BEHIND THE FRONT...SO HIGHS LIKELY REMAINING
ABOVE NORMAL IN THE MID TO UPPER 30S.
SHORT TERM...MONDAY NIGHT THROUGH WEDNESDAY.
FOCUS OF THIS PERIOD ON INCREASING THREAT OF LIGHT PRECIPITATION TUE
AFTN AND NIGHT. QUIET CONDITIONS SHOULD CONTINUE MONDAY NIGHT INTO
TUE MRNG OVER SRN WI AS MID-LEVEL SHORT WAVE RIDGING AMPLIFIES AHEAD
OF SOUTHERN PLAINS SHORT WAVE. AREAS OF STRATUS MAY INITIALLY STILL
BE OVER PARTS OF SRN WI MON EVE...BUT INCREASING NORTHEAST WINDS WL
PULL DRIER AIR INTO THE REGION AND SHOULD EVENTUALLY THIN CLOUDS.
EVEN WITH A DELTA-T APPROACHING 13C...LOW RH SHOULD KEEP LAKE CLOUDS
AT BAY.
NEED TO BE MORE AGGRESSIVE WITH THREAT OF PRECIP TUE AFTN AND TUE
NIGHT AS LATEST MODEL GUIDANCE NOW BRINGING MID LEVEL CIRCULATION
FARTHER NORTH ACROSS NRN IL/SRN WI AREA LATE TUE NGT. SHORT TERM
GUIDANCE IN GOOD AGREEMENT ON CUTOFF LOW PRESSURE CURRENTLY OVER
SOUTHWEST CONUS TO GET NUDGED EASTWARD INTO THE SRN PLAINS BY
12Z/TUE. CUTOFF LOW OPENS AND ACCELERATES NORTHEAST INTO WRN
GTLAKES BY 12Z/WED. GFS AND ECMWF HAVE BEEN MOST CONSISTENT WITH
THIS SYSTEM...AND HAVE BEEN TRENDING NORTHWARD WITH THE MID-LEVEL
CIRCULATION. INITIAL SURGE OF WARM AIR ADVECTION AND WEAK
ISENTROPIC UPGLIDE PUSHES ACROSS SRN CWA TUE AFTN. CONDENSATION
PRESSURE DEFICITS DECREASE TO LESS THAN 5MB. -SN MAY BEGIN TO CROSS
THE IL BORDER BY LATE MRNG. LOW LEVELS CONTINUE TO WARM TUE AFTN.
TOP DOWN AND CRICITAL THICKNESS ANALYSIS REVEALS MOSTLY LIGHT SNOW
OR LIGHT SLEET THREAT OVER SOUTH CENTRAL WI...WITH MORE LIGHT SNOW
OR RAIN THREAT FARTHER EAST. TEMPS WL ONLY RISE TO A COUPLE DEGREES
ABV FREEZING ON TUE...SO LIGHT ACCUMULATIONS MAY BEGIN TUE AFTN.
INITIAL SURGE OF LIGHT PRECIP MAY TAPER OFF FOR A FEW HOURS AS
ISENTROPIC UPGLIDE AND LOWER CPD PUSH NORTHEAST. SYNOPTIC SCALE
LIFT ASSOCIATED WITH MID-LEVEL CIRCULATION SPREADS INTO SRN WI TUE
NIGHT. SLIGHTLY WARMER AIR AT THE LOW-MID LEVELS CONTINUES TO
ADVANCE INTO SOUTHERN WI AT THIS TIME...HOWEVER TOP DOWN PTYPE
SCENARIO REVEALS ICE CRYSTAL INITIATION BEGINS TO WANE AT TOP OF
CLOUD LAYER. WITH TEMPS AROUND FREEZING...WL BE A THREAT FOR LIGHT
FREEZING RAIN AND SLEET OVER PARTS OF SOUTHERN WI...WITH A BETTER
CHANCE FOR ALL LIQUID CLOSER TO LAKE MI. DRYING AT THE
MID-LEVELS...A LACK OF FRONTOGENESIS AND STRONG Q-VECTOR
CONVERGENCE...SO APPEARS FOR NOW THIS SYSTEM SHOULD REMAIN WEAK AND
RESULT IN LIGHT PRECIP AMOUNTS. BIGGEST THREAT WL BE ICING THREAT
TUE NGT IN PARTS OF SOUTH CENTRAL.
LONG TERM...WEDNESDAY NIGHT THROUGH SUNDAY.
EXPECTING AFFECTS OF EARLY WEEK SYSTEM TO BE WELL EAST OF SRN WI BY
THE START OF THE EXTENDED PERIOD. THE WEATHER PATTERN WILL RETURN
TO A SCENARIO SIMILAR TO CURRENT SITUATION WITH WLY STEERING
CURRENTS IN THE MID LEVELS WHILE NEXT PIECE OF NRN PACIFIC ENERGY
MOVES SOUTHEAST ACROSS WRN CONUS. BY FRI MRNG...CUTOFF MID LEVEL
LOW PRESSURE OVER SOUTHWEST CONUS WL BE NUDGED NORTHEAST BY BUILDING
HIGH PRESSURE IN THE ERN PAC AND NEXT IN A SERIES OF SHORT WAVES
DROPPING DOWN FROM SW CANADA. LATEST GFS AND ECMWF MODEL RUNS SHOW
THIS WEAK LOW PRESSURE SYSTEM MOVING NORTHEAST BRINGING SWATH OF
LIGHT PRECIP TO SRN WI SATURDAY NIGHT...RESULTING IN WIDESPREAD
FRESHENING SNOW COVER XMAS EVE...WITH QUIETER WEATHER RETURNING FOR
EARLY THE FOLLOWING WEEK. HOWEVER CONFIDENCE ON THIS XMAS EVENT LOW
DUE TO LACK OF RUN TO RUN CONSISTENCY AND OTHER LONG TERM GUIDANCE
KEEPING UPPER LOW FARTHER SOUTHWEST AND EVEN WEAKER. IN
FACT...DIFFICULT TO HAVE MUCH CONFIDENCE IN ANY PART OF THE DAY4-7
PERIOD DUE TO SWIFT MID LEVEL FLOW AND TIGHTENING BAROCLINICITY
ACROSS THE UPPER MIDWEST. GFS ENSEMBLES SHOW RAPIDLY DETERIORATING
AGREEMENT BETWEEN MEMBERS FRIDAY NIGHT...WITH CHAOTIC PATTEN
CONTINUING THROUGH THE WEEKEND.
AVIATION /00Z TAFS/...VFR CONDITIONS EXPECTED UNDER MOSTLY CLEAR
SKIES THROUGH LATE AFTERNOON AND INTO THE EVENING. WARM AIR
ADVECTION WILL CONTINUE TONIGHT...WITH STRATUS EXPECTED TO DEVELOP
BELOW THE INVERSION. CIGS LIKELY DROPPING TO MVFR BY MIDNIGHT OR
SHORTLY THEREAFTER. STRONG WINDS ALSO EXPECTED ABOVE THE
INVERSION...WITH A PERIOD OF WIND SHEAR POSSIBLE. MVFR CIGS WILL
PROBABLY STICK AROUND FOR MUCH OF MONDAY.
MARINE...LOW PRESSURE WILL CONTINUE TO PASS BY WELL TO THE NORTH
THIS EVENING...WITH A TIGHTENING PRESSURE GRADIENT ACROSS SOUTHERN
WISCONSIN BETWEEN THE LOW AND HIGH PRESSURE TO THE SOUTHEAST. WINDS
WILL CONTINUE TO INCREASE THIS EVENING INTO TONIGHT...WITH GUSTS TO
SMALL CRAFT LEVELS LATE THIS AFTERNOON UNTIL MONDAY MORNING. WILL
CONTINUE SMALL CRAFT ADVISORY UNTIL 14Z MON. WAVES WILL BUILD TO 2
TO 4 FEET TONIGHT...POSSIBLY TO AROUND 5 FEET NORTH OF PORT
WASHINGTON. HIGHEST WAVES WILL BE TOWARD OPEN WATERS.
NORTH TO NORTHEAST WINDS MAY APPROACH SMALL CRAFT LEVELS TOMORROW
AFTERNOON AND INTO THE EVENING...WITH WAVES TOWARD ILLINOIS POSSIBLY
EXCEEDING 4 FEET MONDAY NIGHT. THIS WILL HAVE TO BE WATCHED FOR
ANOTHER POSSIBLE SMALL CRAFT ADVISORY.
CONFIDENCE...
TONIGHT AND MONDAY...MEDIUM TO HIGH.
MONDAY NIGHT...HIGH.
TUESDAY THROUGH WEDNESDAY...LOW TO MEDIUM.
WEDNESDAY NIGHT THROUGH FRIDAY NIGHT...LOW TO MEDIUM.
SATURDAY THROUGH SUNDAY...LOW.
&&
.MKX WATCHES/WARNINGS/ADVISORIES...
WI...NONE.
LM...SMALL CRAFT ADVISORY UNTIL 8 AM CST MONDAY FOR LMZ643>646.
&&
$$
UPDATE...REM
TONIGHT/MONDAY AND AVIATION/MARINE...DDV
MONDAY NIGHT THROUGH SUNDAY...MBK
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
552 PM CST SUN DEC 18 2011
.SHORT TERM...THROUGH TUESDAY NIGHT
227 PM CST SUN DEC 18 2011
MAIN FORECAST CONCERN IS WITH THE PRECIPITATION CHANCES AND TYPES
TUESDAY AND TUESDAY NIGHT.
SURFACE ANALYSIS THIS AFTERNOON SHOWS AN AREA OF LOW PRESSURE OVER
SOUTHWEST ONTARIO WITH A COLD FRONT EXTENDING SOUTHWEST THROUGH
NORTH DAKOTA.
THE COLD FRONT WILL SLIDE ACROSS THE REGION OVERNIGHT. AS IT
DOES...THE 18.12Z NAM AND 18.18Z RUC SUGGEST THERE WILL BE A
RIBBON OF LOW LEVEL MOISTURE BEHIND THE FRONT THAT SHOULD BE
SUFFICIENT TO ALLOW SATURATION TO OCCUR. THIS SHOULD RESULT IN A
BAND OF STRATUS CLOUDS DEVELOPING ACROSS THE REGION AND HAVE
RAISED THE CLOUD COVER TO HANDLE THIS. OBSERVATIONS ACROSS
SASKATCHEWAN AND MANITOBA DO INDICATE THE EXISTENCE OF THIS
STRATUS ALREADY. THE NAM BUFKIT SOUNDINGS INDICATE SOME VERTICAL
MOTION THROUGH THIS SATURATED LAYER SUGGESTING THE POTENTIAL FOR
SOME DRIZZLE. HOWEVER...THE RUC DOES NOT SHOW THIS AND WILL LEAVE
OUT THE MENTION OF ANY DRIZZLE.
THE FRONT WILL BECOME STATIONARY SOUTH OF THE AREA MONDAY NIGHT AS
THE UPPER LEVEL LOW OVER THE SOUTHWEST STARTS TO EJECT OUT TO THE
NORTHEAST. AS THIS SYSTEM COMES OUT...BOTH THE NAM AND GFS BRING
BETWEEN 4 AND 8 PVU/S OF VORTICITY ADVECTION IN THE 500-300 MB
LAYER ACROSS THE SOUTHERN PARTS OF THE FORECAST AREA TUESDAY AND
TUESDAY NIGHT. THIS IS EXPECTED TO RESULT IN WEAK TO MODERATE QG
CONVERGENCE OCCURRING ACROSS THE FAR SOUTHERN PARTS OF THE
FORECAST AREA. THERE SHOULD ALSO BE SOME WEAK FRONTOGENESIS IN THE
850-500 MB LAYER OF THE SAME AREA. THERE IS ENOUGH OF A CONSENSUS
IN ALL THE MODELS TO BRING THE PRECIPITATION CHANCES TO ABOUT THE
INTERSTATE 90 CORRIDOR TUESDAY AFTERNOON AND NIGHT. BUFKIT
SOUNDINGS FROM BOTH THE NAM AND GFS SUGGEST THERE MAY NOT BE A LOT
OF ICE PRESENT IN THE CLOUDS AS THIS SYSTEM COMES THROUGH. THE
SOUNDINGS SUGGEST CLOUD TOP TEMPERATURES MAY BE IN THE -10 TO -12C
RANGE AND THERE COULD ALSO BE A BIT OF A WARM LAYER ALOFT AT TIMES
AS WELL. HAVE THUS ADDED IN SOME PROBABILITIES OF FREEZING RAIN
AND WILL HAVE A MIXTURE OF RAIN...SNOW AND FREEZING RAIN. ACTUAL
PRECIPITATION AMOUNTS SHOULD BE VERY LIGHT AND ANY SNOW OR ICE
ACCUMULATIONS THAT OCCUR SHOULD NOT AMOUNT TO MUCH.
.LONG TERM...WEDNESDAY THROUGH SUNDAY
227 PM CST SUN DEC 18 2011
AS THE SYSTEM PULLS AWAY FROM THE AREA WEDNESDAY...THERE COULD
STILL BE A LITTLE BIT OF LINGERING PRECIPITATION ACROSS THE FAR
SOUTHEASTERN PARTS OF THE FORECAST AREA. THE NEXT NORTHERN STREAM
SHORT WAVE TROUGH IS EXPECTED TO COME ACROSS THE UPPER MIDWEST
WEDNESDAY NIGHT AND THURSDAY. MODELS HAVE BEEN INCONSISTENT ON
WHETHER THIS WILL BE ENOUGH TO PRODUCE SOME LIGHT SNOW AS THE WEAK
COLD FRONT COMES THROUGH. FOR NOW...WILL STAY WITH THE CURRENT
MODEL CONSENSUS GRIDS SHOWING THE SNOW CHANCES FARTHER NORTH
CLOSER TO THE SHORT WAVE TROUGH...BUT COULD SEE LATER FORECASTS
ADDING IN SOME SNOW CHANCES FOR THIS SYSTEM. ANOTHER WAVE WILL BE
DROPPING INTO THE UPPER MIDWEST NEXT SUNDAY AND WILL HAVE SOME
SMALL SNOW CHANCES ACROSS THE NORTH WITH THIS SYSTEM.
&&
.AVIATION...TONIGHT AND MONDAY
552 PM CST SUN DEC 18 2011
VFR CONDITIONS TO CONTINUE THROUGH THE EVENING WITH WARM SOUTHERLY
FLOW THROUGH MUCH OF THE UPPER MISSISSIPPI VALLEY REGION. THIS
WILL ALL CHANGE LATER IN THE NIGHT INTO TOMORROW MORNING AS A COLD
FRONT DROPS DOWN FROM CANADA THROUGH THE REGION. WINDS WILL SHIFT
FROM THE SOUTHWEST TO THE NORTHWEST AFTER THE FRONT COMES THROUGH
RST/LSE AROUND 9Z/10Z. THE MAIN CHALLENGE WITH THE FORECAST IS
WITH TRYING TO TIME THE DEVELOPMENT OF SOME LOW LEVEL STRATUS
OVERNIGHT. IT APPEARS THAT THE BEST CHANCES FOR CEILINGS TO DROP
WILL BE AFTER THE FRONT PASSES THROUGH AND LOW LEVEL LAPSE RATES
STEEPEN UP. THIS 500-900FT STRATUS DECK SHOULD STICK AROUND
THROUGH MUCH OF THE DAY MONDAY BUT COULD LIFT A BIT AS THE
INVERSION STARTS TO LIFT AS COOLER LOW LEVEL AIR ADVECTS INTO THE
REGION. WINDS WILL LIKELY BE GUSTY IN THE 18-22KT RANGE AS WELL
THROUGH MUCH OF THE DAY AT BOTH LSE AND RST.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
227 PM CST SUN DEC 18 2011
WI...NONE.
MN...NONE.
IA...NONE.
&&
$$
SHORT TERM...04
LONG TERM...04
AVIATION...HALBACH
AREA FORECAST DISCUSSION...UPDATED
NWS MILWAUKEE/SULLIVAN WI
1146 AM CST SAT DEC 17 2011
.UPDATE...LOW CLOUD COVER OVER MOST OF CWA KEEPING TEMPS COOLER THAN
PREVIOUSLY FORECAST. LIKEWISE...DEEPER THAN EXPECTED SNOW COVER OVER
THE SOUTHWEST COULD HELP HOLD TEMPS DOWN. WILL LOWER HIGHS EXCEPT IN
THE NORTHEAST WHERE THERE IS LESS SNOW AND SKIES WERE CLEARER THIS
MORNING. PERSISTENT FLURRIES OVER THE SOUTHEAST ASSOCIATED WITH LOW
LEVEL CONVERGENCE IN NEAR SATURATED LAYER. CONVERGENCE EXPECTED TO
WEAKEN AND LAYER TO DRY SO DO NOT EXPECT MORE SIGNIFICANT PRECIP TO
RESULT.
&&
.AVIATION/18Z TAFS/...LOWER CIGS CONTINUE TO SPREAD NORTHEAST
THROUGH SOUTHERN WISCONSIN. LOOKS LIKE MOST PLACES WILL HAVE MVFR
CIGS THROUGH THE AFTERNOON...AND POSSIBLY INTO THE EVENING GIVEN
LATEST MODEL 925 MB RH. MAY SEE IFR CIGS FOR A TIME. CLOUDS
EXPECTED TO THEN DECREASE WEST TO EAST THIS EVENING...WITH JUST
SCATTERED MID OR HIGH LEVEL CLOUDS REMAINING BY MIDNIGHT. VFR
CONDITIONS THEN EXPECTED THROUGH SUNDAY AS HIGH PRESSURE SLIDES BY
TO THE SOUTHEAST.
&&
.PREV DISCUSSION... /ISSUED 326 AM CST SAT DEC 17 2011/
TODAY AND TONIGHT...FORECAST CONFIDENCE...MEDIUM
SHORTWAVE AND ISENTROPIC LIFT GENERATING A BAND OF LIGHT SNOW THAT
WILL MOVE ACROSS MUCH OF THE FORECAST AREA. HIGHEST AMOUNTS WILL
BE ACROSS THE SOUTHWEST HALF WITH LIGHTER AMOUNTS TOWARD FOND DU
LAC AND SHEBOYGAN. LATEST NAM AND HRRR HAVE A GOOD HANDLE ON IT
AND EXPECT A BAND OF 1 TO 2 INCHES OVER THE SOUTHWEST HALF OF THE
FORECAST AREA. A FEW 3 INCH TOTALS ARE POSSIBLE MAINLY WEST AND
SOUTHWEST OF MADISON.
SNOW WILL PULL OUT OF THE EAST IN THE MORNING. ANOTHER SHORTWAVE
WILL DROP ACROSS MAINLY NORTHERN WISCONSIN DURING THE AFTERNOON
AND EARLY EVENING...MAYBE BRINGING SOME LIGHT SNOW TOWARD FOND DU
LAC AND SHEBOYGAN. OVERALL SETUP NOT AS GOOD AS FIRST WAVE THOUGH
WITH BEST LIFT TO THE NORTH.
ANOTHER WEAKER SHORTWAVE AND MID LEVEL WARM ADVECTION LATE TONIGHT
IN A FAST NORTHWEST FLOW. HOWEVER MAINLY MID LEVEL CLOUDS WITH
THIS FEATURE AND NO PRECIPITATION EXPECTED.
SHORT TERM...SUNDAY THROUGH MONDAY NIGHT...FORECAST CONFIDENCE
MEDIUM.
WARM AIR ADVECTION CONTINUES ACROSS THE AREA ON SUNDAY. PUSH OF
DRIER AIR INTO THE AREA WILL GRADUALLY PUSH OUT CLOUDS AS THE DAY
GOES ON. A MILD DAY IS EXPECTED...WITH LOWER TO MID 40S FOR HIGHS.
SOUTHWEST WINDS CONTINUE TO HOLD THE MILD AIRMASS ACROSS THE AREA
SUNDAY NIGHT...AS A COLD FRONT MOVES SOUTHEAST INTO THE AREA. NAM
INDICATING SOME POTENTIAL FOR LOW STRATUS DEVELOPMENT DURING THIS
TIME...WITH THE GFS SOMEWHAT LESS AGGRESSIVE WITH THE LOW LEVEL
SATURATION. WILL TREND TOWARDS MOSTLY CLOUDY SKIES LATE SUNDAY
NIGHT. NAM INDICATING LIGHT QPF WITH THE FRONT...WITH THE
GFS/ECMWF DRY. NAM FORECAST SOUNDINGS NOT IMPRESSIVE WITH MOISTURE
PROFILE ABOVE INVERSION...SO LEFT THIS PERIOD DRY.
COLD FRONT SLIDES SOUTHEAST ACROSS THE AREA DURING THE MORNING ON
MONDAY...THEN SOUTHEAST IN THE AFTERNOON. NAM/GFS FORECAST
SOUNDINGS STILL NOT SHOWING MUCH WITH MOISTURE ABOVE INVERSION IN
THE MORNING...WITH A DRYING TREND WITH COLD AIR ADVECTION IN THE
AFTERNOON. KEPT SLIGHT CHANCES FOR LIGHT RAIN AND LIGHT SNOW IN
THE FAR SOUTHEAST COUNTIES MONDAY...CLOSEST TO THE FRONT. HIGHS
WILL BE MILD UNTIL FRONTAL PASSAGE...WITH A FALL DURING THE
AFTERNOON.
HIGH PRESSURE MOVING INTO THE REGION MONDAY NIGHT WILL BRING A
REINFORCING SHOT OF DRY AIR ACROSS THE AREA. STRONG VORTICITY
MAXIMUM SHIFTING SOUTHEAST THROUGH THE AREA MAY BE ENOUGH FOR
LIGHT SNOW. CONTINUED TO KEEP LOW END POPS MONDAY NIGHT IN THE FAR
SOUTHEAST COUNTIES. LOW TEMPERATURES SHOULD BE MORE SEASONABLE
WITH THE COLDER AIR MOVING INTO THE AREA.
LONG TERM...TUESDAY THROUGH FRIDAY...FORECAST CONFIDENCE LOW TO
MEDIUM.
GFS/ECMWF IN SOMEWHAT BETTER AGREEMENT WITH SYSTEM FOR
TUESDAY...THEN CONTINUE TO DIFFER TUESDAY NIGHT AND WEDNESDAY.
THEY BOTH ARE KEEPING THE SURFACE LOW WELL SOUTH OF THE AREA. THEY
TAKE IT EAST NORTHEAST FROM THE SOUTHERN PLAINS TO THE MIDDLE
MISSISSIPPI RIVER VALLEY TUESDAY ON THE GFS...THEN INTO
OHIO/EASTERN PENNSYLVANIA TUESDAY NIGHT. THE STRONG UPPER LOW
LINGERS TO THE NORTHWEST OF THE SURFACE LOW...TAKING A SIMILAR
EAST NORTHEAST PATH.
THE ECMWF CONTINUES TO BE SLOWER WITH THIS SYSTEM...AND DOES NOT
HAVE THE SURFACE LOW IN THE MIDDLE MISSISSIPPI RIVER VALLEY UNTIL
LATE TUESDAY NIGHT/EARLY WEDNESDAY. IT THEN MOVES THE LOW EAST
NORTHEAST FROM THERE WEDNESDAY INTO WEDNESDAY NIGHT. ITS
PRECIPITATION SHIELD MISSES SOUTHERN WISCONSIN. HAVE SEEN SYSTEMS
LIKE THESE TREND SOUTHWARD...ONLY TO TREND BACK NORTH AND BRING
THE AREA PRECIPITATION. FOR NOW...WILL MAINTAIN SMALL CHANCES FOR
PRECIPITATION ACROSS THE SOUTHEAST COUNTIES.
MODELS SHOW HIGH PRESSURE PASSING SOUTH OF THE AREA WEDNESDAY.
THIS SHOULD BRING QUIET WEATHER...WITH MILD TEMPERATURES.
MODELS THEN BRING A COLD FRONT THROUGH THE AREA THURSDAY...WITH NO
QPF ASSOCIATED WITH IT. MORE DIFFERENCES THEN OCCUR BETWEEN THESE
MODELS INTO FRIDAY. THE GFS BRINGS AN AMPLIFIED SHORTWAVE TROUGH
SOUTHEAST THROUGH THE REGION THURSDAY NIGHT AND FRIDAY...WITH THE
ECMWF CLIPPING THIS AREA FRIDAY. QPF IS LIGHT WITH THE GFS...EVEN
WITH THE STRONG SHORTWAVE TROUGH. FOR NOW...WILL LEAN TOWARD
CONSENSUS POPS AND TEMPERATURES THIS FAR OUT IN THE FORECAST.
AVIATION/12Z TAFS/...
MAINLY MVFR CIGS AND IFR VSBY EARLY THIS MORNING OVER MUCH OF THE
FORECAST AREA EXCEPT NORTHEAST TOWARD SHEBOYGAN.
ANOTHER ROUND OF LIGHT SNOW MAY SLIDE THROUGH THE NORTHEAST THIRD
OF THE FORECAST AREA LATE THIS AFTERNOON AND INTO THE
EVENING...BUT BEST MOISTURE AND LIFT EXPECTED TO PASS BY TO THE
NORTH AND NORTHEAST.
MAINLY MID LEVEL VFR CLOUDS TONIGHT.
MARINE...
SOUTH WINDS WILL INCREASE ON SUNDAY AHEAD OF LOW PRESSURE MOVING
NORTH OF LAKE SUPERIOR...WITH WINDS AND WAVES LIKELY REACHING
SMALL CRAFT CRITERIA.
&&
.MKX WATCHES/WARNINGS/ADVISORIES...
WI...NONE.
LM...NONE.
&&
$$
UPDATE...WIMBERLEY/DDV
TODAY/TONIGHT AND AVIATION/MARINE...HENTZ
SUNDAY THROUGH FRIDAY...WOOD
AREA FORECAST DISCUSSION
NWS GREEN BAY WI
1139 AM CST SAT DEC 17 2011
UPDATED AVIATION PORTION FOR 18Z TAF ISSUANCE
.SYNOPSIS...A RELATIVELY QUIET PERIOD FOR MID-DECEMBER WITH
TEMPERATURES ABV SEASONAL NORMALS.
CLASSIC SPLIT FLOW REGIME WL CONT ACRS NOAM THROUGH THE PERIOD AND
BEYOND. THE FCST AREA WL BE UNDER THE INFLUENCE OF THE NRN STREAM
THROUGH AT LEAST THE MIDDLE OF NEXT WK. THE PATTERN COMBINED WITH
LACK OF SIG SNOW COVER ACRS THE RGN SUPPORTS ABV NORMAL TEMPS. NRN
STREAM SYSTEMS WL BRING SOME LGT PCPN AT TIMES...BUT AMNTS WL END
UP BLO NORMAL.
&&
.SHORT TERM...TDA/TNGT/SUN. WV PASSING S OF THE AREA WL BRUSH THE
FAR S WITH SOME S-/S-- EARLY TDA. ALSO NEED TO KEEP AN EYE ON THE
LAKE-EFFECT POTENTIAL AS HRRR WAS DEVELOPING CYCLONIC CIRCULATION
OVER CENTRAL LAKE MICHIGAN...AND SFC OBS SEEM TO BE BEARING THAT
OUT.
BETTER CHC OF PCPN WL COME TO THE NE 1/2 OF THE FCST AREA THIS
AFTN AS THE NEXT NRN STREAM SHRTWV PUSHES INTO THE RGN. THE
COMBINATION OF QG FORCING WITH THE MID-LVL SHRTWV...ISENT LIFT...
AND DIV IN LFQ OF UPR JET SUPPORTED KEEPING LIKELY POPS OVER THE
NE. CONT TO HAVE POPS TAPER BACK TO CHC TO THE SW...WHICH WL ONLY
BE BRUSHED BY THE BETTER FORCING. EXPECT A FAIRLY FAST MOVG BAND
OF SN TO PUSH ACRS DURING THE AFTN. WL STICK WITH MENTION OF UP TO
AN INCH OVER THE NE.
SUBSIDENCE BEHIND THE WV AND DEEP WLY FLOW SHOULD HELP STRIP OUT
LOW AND MIDDLE CLDS TNGT. COULD BE SOME HIGH CLDS WORKING BACK IN
LATE. SOME SFC PRESSURE GRADIENT REMAINS...BUT PROBABLY NOT ENOUGH
TO RELY ON TO KEEP TEMPS UP. TENDED DOWN WITH TEMPS OVER THE NRN
PART OF THE AREA.
WARMER AIR WL BEGIN FLOWING BACK INTO THE AREA SUN. BUT THE BULK
OF THE WARMING WL BE ALOFT. STAYED RATHER CONSERVATIVE WITH MAX
TEMP FCST AS IT WL TAKE A WHILE FOR WARMER AIR TO WORK IN AT THE
SFC. ALSO STAYED RATHER MODEST WITH WINDS AS STRONGEST FLOW WL BE
ABV THE SFC AND POTENTIAL FOR MIXING WL BE VERY LTD.
.LONG TERM...SUNDAY NGT THRU NXT FRI. LITTLE CHG IN THE OVERALL
SYNOPTIC PATN ACROSS THE CONUS DURING THE EXTENDED PERIOD WITH
SPLIT FLOW PERSISTING UNTIL FURTHER NOTICE. EARLY WEEK SYSTEM NOW
DOES APR TO STAY TO OUR SOUTH...THUS NO SNOW WITH THIS FEATURE.
MAIN FCST FOCUS TO BE ON TEMPS INITIALLY AND THEN WL HAVE TO WATCH
LATE NXT WEEK FOR THE NXT SNOW CHC.
MDLS CONT TO SHOW A CDFNT RACING THRU ALL BUT SE WI SUNDAY NGT...
BRINGING SOME CLOUDS AND A WIND SHIFT BUT NO PCPN AS TIME SECTIONS/
FCST SNDNGS SHOW LITTLE MSTR IN THE MID-LVLS OF THE ATM. SINCE
BETTER FORCING REMAINS WELL TO OUR NORTH IN THE VCNTY OF THE
PRIMARY SHRTWV AND MSTR TO BE LIMITED...HAVE GONE WITH A DRY FROPA.
WINDS WL REMAIN RATHER MODEST THRU MOST OF THE NGT WHICH WOULD
HELP PREVENT TEMPS FROM FALLING MUCH. IN FACT...MIN TEMPS ARE
EXPECTED TO BE NEAR NORMAL MAX TEMPS FOR THIS TIME OF YEAR (LWR 20S
NORTH TO UPR 20S E-CNTRL).
WINDS TO VEER MORE NW BY MON MORNING WITH MODEST LEVELS OF CAA
TAKING OVER WI THRU THE DAY. 8H TEMPS OVER LK SUPERIOR DROP TO
AROUND -10C WHICH WOULD RAISE DELTA-T VALUES INTO THE MID TEENS
AND LEAD TO THE POSSIBILITY OF LK EFFECT SNOW SHWRS PRIMARILY
ACROSS VILAS CNTY. THESE SNOW SHWRS HOWEVER DO NOT LOOK SIGNIFICANT
AS HI PRES ALREADY BUILDING INTO THE WRN GREAT LKS AND ADVECTING
DRY AIR INTO THE RGN. HAVE ONLY KEPT A TOKEN POP FOR VILAS CNTY
WITH ONLY A COUPLE TENTHS OF AN INCH EXPECTED. THE REST OF THE FCST
AREA SHOULD SEE A MIX OF SUN AND CLOUDS WITH MAX TEMPS RANGING FROM
AROUND 30 NORTH TO THE MID 30S E-CNTRL WI.
THIS HI PRES TO THEN SPRAWL ACROSS THE GREAT LKS MON NGT WITH SKIES
BECMG MOSTLY CLEAR AND WINDS BECMG LGT/VRBL. THIS SHOULD ALLOW
TEMPS TO CRASH AND WL NEED TO CHOP A GOOD 3 TO 5 DEGS FROM THE PREV
FCST. COULD EASILY SEE THE COLD SPOTS OF NRN WI DROP INTO THE
SINGLE DIGITS WHILE ONLY AREAS NEAR LK MI HOLD IN THE 20S. AFTER
DAYS OF MDL INCONSISTENCY WITH THE HANDLING OF A PSBL NRN/SRN
STREAM PHASING/STORM TRACK ISSUES ON TUE...THE MEDIUM RANGE MDLS
HAVE COME INTO AGREEMENT THAT ANY PHASING WOULD NOT OCCUR UNTIL
FARTHER TO OUR EAST. THIS TRANSLATES TO THE SRN STREAM UPR LOW
STAYING FAR ENUF SOUTH SUCH THAT ANY ACCUMULATING SNOW WOULD ONLY
REACH FAR SRN WI AT BEST. STILL EXPECT TO SEE SOME CLOUDS TO
INCREASE OVER THE SE HALF OF THE FCST AREA ON TUE...BUT NON POPS
WL BE NEEDED.
WHILE THE SRN STREAM SYSTEM CONTS TO LIFT NE INTO THE OHIO RIVER
VALLEY TUE NGT...THE TRAILING NRN STREAM SHRTWV TROF MOVES THRU
THE WRN GREAT LKS AND SENDS A CDFNT THRU WI. ONCE AGAIN...BETTER
FORCING GOES EITHER NORTH OR SOUTH OF WI...THUS A CONTINUATION OF
A DRY FCST. A WEAK SFC RDG IS THEN FCST TO MOVE ACROSS MAINLY THE
SRN SECTIONS OF THE GREAT LKS LATER TUE NGT INTO WED. UNDER MOSTLY
CLEAR TO PARTLY CLDY SKIES...LOOK FOR TEMPS TO REMAIN WELL ABV
NORMAL.
FCST BECOME MORE MUDDLED FOR THE LATTER PART OF THE WORK WEEK AS
THE NXT SIGNIFICANT NRN STREAM SHRTWV ENERGY DROPS SE INTO THE
GREAT BASIN. ISSUES AMONG THE MDLS CENTER ON WHETHER THIS ENERGY
WL CLOSE OFF TO ANOTHER CLOSED UPR LOW OR PROGRESS EAST WITH TIME
AND INCREASE SNOW CHCS ACROSS WI. A PROGRESSIVE SOLN WOULD BRING A
LGT SNOW POTENTIAL TO NE WI BY THU NGT INTO FRI...BUT WITH ALL THE
UNCERTAINTY INVOLVED AT THIS TIME...HAVE GONE WITH THE MDL
CONSENSUS SOLN OF ONLY SLGT CHC POPS FOR NOW.
&&
.AVIATION...CIGS GENERALLY BETWEEN 1000` AND 2000` AGL THROUGH
EARLY EVENING. AN UPPER LEVEL DISTURBANCE WILL PRODUCE SOME
SCATTERED SNOW SHOWERS WITH BRIEF IFR CIGS AND VSBYS. SHOULD
BECOME GENERALLY VFR LATE TONIGHT. VFR CIGS BETWEEN 5000` AND
10000` AGL SUNDAY.
RDM
&&
.GRB WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS MILWAUKEE/SULLIVAN WI
326 AM CST SAT DEC 17 2011
.TODAY AND TONIGHT...FORECAST CONFIDENCE...MEDIUM
SHORTWAVE AND ISENTROPIC LIFT GENERATING A BAND OF LIGHT SNOW THAT
WILL MOVE ACROSS MUCH OF THE FORECAST AREA. HIGHEST AMOUNTS WILL
BE ACROSS THE SOUTHWEST HALF WITH LIGHTER AMOUNTS TOWARD FOND DU
LAC AND SHEBOYGAN. LATEST NAM AND HRRR HAVE A GOOD HANDLE ON IT
AND EXPECT A BAND OF 1 TO 2 INCHES OVER THE SOUTHWEST HALF OF THE
FORECAST AREA. A FEW 3 INCH TOTALS ARE POSSIBLE MAINLY WEST AND
SOUTHWEST OF MADISON.
SNOW WILL PULL OUT OF THE EAST IN THE MORNING. ANOTHER SHORTWAVE
WILL DROP ACROSS MAINLY NORTHERN WISCONSIN DURING THE AFTERNOON
AND EARLY EVENING...MAYBE BRINGING SOME LIGHT SNOW TOWARD FOND DU
LAC AND SHEBOYGAN. OVERALL SETUP NOT AS GOOD AS FIRST WAVE THOUGH
WITH BEST LIFT TO THE NORTH.
ANOTHER WEAKER SHORTWAVE AND MID LEVEL WARM ADVECTION LATE TONIGHT
IN A FAST NORTHWEST FLOW. HOWEVER MAINLY MID LEVEL CLOUDS WITH
THIS FEATURE AND NO PRECIPITATION EXPECTED.
.SHORT TERM...SUNDAY THROUGH MONDAY NIGHT...FORECAST CONFIDENCE
MEDIUM.
WARM AIR ADVECTION CONTINUES ACROSS THE AREA ON SUNDAY. PUSH OF
DRIER AIR INTO THE AREA WILL GRADUALLY PUSH OUT CLOUDS AS THE DAY
GOES ON. A MILD DAY IS EXPECTED...WITH LOWER TO MID 40S FOR HIGHS.
SOUTHWEST WINDS CONTINUE TO HOLD THE MILD AIRMASS ACROSS THE AREA
SUNDAY NIGHT...AS A COLD FRONT MOVES SOUTHEAST INTO THE AREA. NAM
INDICATING SOME POTENTIAL FOR LOW STRATUS DEVELOPMENT DURING THIS
TIME...WITH THE GFS SOMEWHAT LESS AGGRESSIVE WITH THE LOW LEVEL
SATURATION. WILL TREND TOWARDS MOSTLY CLOUDY SKIES LATE SUNDAY
NIGHT. NAM INDICATING LIGHT QPF WITH THE FRONT...WITH THE
GFS/ECMWF DRY. NAM FORECAST SOUNDINGS NOT IMPRESSIVE WITH MOISTURE
PROFILE ABOVE INVERSION...SO LEFT THIS PERIOD DRY.
COLD FRONT SLIDES SOUTHEAST ACROSS THE AREA DURING THE MORNING ON
MONDAY...THEN SOUTHEAST IN THE AFTERNOON. NAM/GFS FORECAST
SOUNDINGS STILL NOT SHOWING MUCH WITH MOISTURE ABOVE INVERSION IN
THE MORNING...WITH A DRYING TREND WITH COLD AIR ADVECTION IN THE
AFTERNOON. KEPT SLIGHT CHANCES FOR LIGHT RAIN AND LIGHT SNOW IN
THE FAR SOUTHEAST COUNTIES MONDAY...CLOSEST TO THE FRONT. HIGHS
WILL BE MILD UNTIL FRONTAL PASSAGE...WITH A FALL DURING THE
AFTERNOON.
HIGH PRESSURE MOVING INTO THE REGION MONDAY NIGHT WILL BRING A
REINFORCING SHOT OF DRY AIR ACROSS THE AREA. STRONG VORTICITY
MAXIMUM SHIFTING SOUTHEAST THROUGH THE AREA MAY BE ENOUGH FOR
LIGHT SNOW. CONTINUED TO KEEP LOW END POPS MONDAY NIGHT IN THE FAR
SOUTHEAST COUNTIES. LOW TEMPERATURES SHOULD BE MORE SEASONABLE
WITH THE COLDER AIR MOVING INTO THE AREA.
.LONG TERM...TUESDAY THROUGH FRIDAY...FORECAST CONFIDENCE LOW TO
MEDIUM.
GFS/ECMWF IN SOMEWHAT BETTER AGREEMENT WITH SYSTEM FOR
TUESDAY...THEN CONTINUE TO DIFFER TUESDAY NIGHT AND WEDNESDAY.
THEY BOTH ARE KEEPING THE SURFACE LOW WELL SOUTH OF THE AREA. THEY
TAKE IT EAST NORTHEAST FROM THE SOUTHERN PLAINS TO THE MIDDLE
MISSISSIPPI RIVER VALLEY TUESDAY ON THE GFS...THEN INTO
OHIO/EASTERN PENNSYLVANIA TUESDAY NIGHT. THE STRONG UPPER LOW
LINGERS TO THE NORTHWEST OF THE SURFACE LOW...TAKING A SIMILAR
EAST NORTHEAST PATH.
THE ECMWF CONTINUES TO BE SLOWER WITH THIS SYSTEM...AND DOES NOT
HAVE THE SURFACE LOW IN THE MIDDLE MISSISSIPPI RIVER VALLEY UNTIL
LATE TUESDAY NIGHT/EARLY WEDNESDAY. IT THEN MOVES THE LOW EAST
NORTHEAST FROM THERE WEDNESDAY INTO WEDNESDAY NIGHT. ITS
PRECIPITATION SHIELD MISSES SOUTHERN WISCONSIN. HAVE SEEN SYSTEMS
LIKE THESE TREND SOUTHWARD...ONLY TO TREND BACK NORTH AND BRING
THE AREA PRECIPITATION. FOR NOW...WILL MAINTAIN SMALL CHANCES FOR
PRECIPITATION ACROSS THE SOUTHEAST COUNTIES.
MODELS SHOW HIGH PRESSURE PASSING SOUTH OF THE AREA WEDNESDAY.
THIS SHOULD BRING QUIET WEATHER...WITH MILD TEMPERATURES.
MODELS THEN BRING A COLD FRONT THROUGH THE AREA THURSDAY...WITH NO
QPF ASSOCIATED WITH IT. MORE DIFFERENCES THEN OCCUR BETWEEN THESE
MODELS INTO FRIDAY. THE GFS BRINGS AN AMPLIFIED SHORTWAVE TROUGH
SOUTHEAST THROUGH THE REGION THURSDAY NIGHT AND FRIDAY...WITH THE
ECMWF CLIPPING THIS AREA FRIDAY. QPF IS LIGHT WITH THE GFS...EVEN
WITH THE STRONG SHORTWAVE TROUGH. FOR NOW...WILL LEAN TOWARD
CONSENSUS POPS AND TEMPERATURES THIS FAR OUT IN THE FORECAST.
&&
.AVIATION/12Z TAFS/...
MAINLY MVFR CIGS AND IFR VSBY EARLY THIS MORNING OVER MUCH OF THE
FORECAST AREA EXCEPT NORTHEAST TOWARD SHEBOYGAN.
ANOTHER ROUND OF LIGHT SNOW MAY SLIDE THROUGH THE NORTHEAST THIRD
OF THE FORECAST AREA LATE THIS AFTERNOON AND INTO THE
EVENING...BUT BEST MOISTURE AND LIFT EXPECTED TO PASS BY TO THE
NORTH AND NORTHEAST.
MAINLY MID LEVEL VFR CLOUDS TONIGHT.
&&
.MARINE...
SOUTH WINDS WILL INCREASE ON SUNDAY AHEAD OF LOW PRESSURE MOVING
NORTH OF LAKE SUPERIOR...WITH WINDS AND WAVES LIKELY REACHING
SMALL CRAFT CRITERIA.
&&
.MKX WATCHES/WARNINGS/ADVISORIES...
WI...NONE.
LM...NONE.
&&
$$
TODAY/TONIGHT AND AVIATION/MARINE...HENTZ
SUNDAY THROUGH FRIDAY...WOOD
AREA FORECAST DISCUSSION
NWS GREEN BAY WI
303 AM CST SAT DEC 17 2011
.SYNOPSIS...A RELATIVELY QUIET PERIOD FOR MID-DECEMBER WITH
TEMPERATURES ABV SEASONAL NORMALS.
CLASSIC SPLIT FLOW REGIME WL CONT ACRS NOAM THROUGH THE PERIOD AND
BEYOND. THE FCST AREA WL BE UNDER THE INFLUENCE OF THE NRN STREAM
THROUGH AT LEAST THE MIDDLE OF NEXT WK. THE PATTERN COMBINED WITH
LACK OF SIG SNOW COVER ACRS THE RGN SUPPORTS ABV NORMAL TEMPS. NRN
STREAM SYSTEMS WL BRING SOME LGT PCPN AT TIMES...BUT AMNTS WL END
UP BLO NORMAL.
&&
.SHORT TERM...TDA/TNGT/SUN. WV PASSING S OF THE AREA WL BRUSH THE
FAR S WITH SOME S-/S-- EARLY TDA. ALSO NEED TO KEEP AN EYE ON THE
LAKE-EFFECT POTENTIAL AS HRRR WAS DEVELOPING CYCLONIC CIRCULATION
OVER CENTRAL LAKE MICHIGAN...AND SFC OBS SEEM TO BE BEARING THAT
OUT.
BETTER CHC OF PCPN WL COME TO THE NE 1/2 OF THE FCST AREA THIS
AFTN AS THE NEXT NRN STREAM SHRTWV PUSHES INTO THE RGN. THE
COMBINATION OF QG FORCING WITH THE MID-LVL SHRTWV...ISENT LIFT...
AND DIV IN LFQ OF UPR JET SUPPORTED KEEPING LIKELY POPS OVER THE
NE. CONT TO HAVE POPS TAPER BACK TO CHC TO THE SW...WHICH WL ONLY
BE BRUSHED BY THE BETTER FORCING. EXPECT A FAIRLY FAST MOVG BAND
OF SN TO PUSH ACRS DURING THE AFTN. WL STICK WITH MENTION OF UP TO
AN INCH OVER THE NE.
SUBSIDENCE BEHIND THE WV AND DEEP WLY FLOW SHOULD HELP STRIP OUT
LOW AND MIDDLE CLDS TNGT. COULD BE SOME HIGH CLDS WORKING BACK IN
LATE. SOME SFC PRESSURE GRADIENT REMAINS...BUT PROBABLY NOT ENOUGH
TO RELY ON TO KEEP TEMPS UP. TENDED DOWN WITH TEMPS OVER THE NRN
PART OF THE AREA.
WARMER AIR WL BEGIN FLOWING BACK INTO THE AREA SUN. BUT THE BULK
OF THE WARMING WL BE ALOFT. STAYED RATHER CONSERVATIVE WITH MAX
TEMP FCST AS IT WL TAKE A WHILE FOR WARMER AIR TO WORK IN AT THE
SFC. ALSO STAYED RATHER MODEST WITH WINDS AS STRONGEST FLOW WL BE
ABV THE SFC AND POTENTIAL FOR MIXING WL BE VERY LTD.
.LONG TERM...SUNDAY NGT THRU NXT FRI. LITTLE CHG IN THE OVERALL
SYNOPTIC PATN ACROSS THE CONUS DURING THE EXTENDED PERIOD WITH
SPLIT FLOW PERSISTING UNTIL FURTHER NOTICE. EARLY WEEK SYSTEM NOW
DOES APR TO STAY TO OUR SOUTH...THUS NO SNOW WITH THIS FEATURE.
MAIN FCST FOCUS TO BE ON TEMPS INITIALLY AND THEN WL HAVE TO WATCH
LATE NXT WEEK FOR THE NXT SNOW CHC.
MDLS CONT TO SHOW A CDFNT RACING THRU ALL BUT SE WI SUNDAY NGT...
BRINGING SOME CLOUDS AND A WIND SHIFT BUT NO PCPN AS TIME SECTIONS/
FCST SNDNGS SHOW LITTLE MSTR IN THE MID-LVLS OF THE ATM. SINCE
BETTER FORCING REMAINS WELL TO OUR NORTH IN THE VCNTY OF THE
PRIMARY SHRTWV AND MSTR TO BE LIMITED...HAVE GONE WITH A DRY FROPA.
WINDS WL REMAIN RATHER MODEST THRU MOST OF THE NGT WHICH WOULD
HELP PREVENT TEMPS FROM FALLING MUCH. IN FACT...MIN TEMPS ARE
EXPECTED TO BE NEAR NORMAL MAX TEMPS FOR THIS TIME OF YEAR (LWR 20S
NORTH TO UPR 20S E-CNTRL).
WINDS TO VEER MORE NW BY MON MORNING WITH MODEST LEVELS OF CAA
TAKING OVER WI THRU THE DAY. 8H TEMPS OVER LK SUPERIOR DROP TO
AROUND -10C WHICH WOULD RAISE DELTA-T VALUES INTO THE MID TEENS
AND LEAD TO THE POSSIBILITY OF LK EFFECT SNOW SHWRS PRIMARILY
ACROSS VILAS CNTY. THESE SNOW SHWRS HOWEVER DO NOT LOOK SIGNIFICANT
AS HI PRES ALREADY BUILDING INTO THE WRN GREAT LKS AND ADVECTING
DRY AIR INTO THE RGN. HAVE ONLY KEPT A TOKEN POP FOR VILAS CNTY
WITH ONLY A COUPLE TENTHS OF AN INCH EXPECTED. THE REST OF THE FCST
AREA SHOULD SEE A MIX OF SUN AND CLOUDS WITH MAX TEMPS RANGING FROM
AROUND 30 NORTH TO THE MID 30S E-CNTRL WI.
THIS HI PRES TO THEN SPRAWL ACROSS THE GREAT LKS MON NGT WITH SKIES
BECMG MOSTLY CLEAR AND WINDS BECMG LGT/VRBL. THIS SHOULD ALLOW
TEMPS TO CRASH AND WL NEED TO CHOP A GOOD 3 TO 5 DEGS FROM THE PREV
FCST. COULD EASILY SEE THE COLD SPOTS OF NRN WI DROP INTO THE
SINGLE DIGITS WHILE ONLY AREAS NEAR LK MI HOLD IN THE 20S. AFTER
DAYS OF MDL INCONSISTENCY WITH THE HANDLING OF A PSBL NRN/SRN
STREAM PHASING/STORM TRACK ISSUES ON TUE...THE MEDIUM RANGE MDLS
HAVE COME INTO AGREEMENT THAT ANY PHASING WOULD NOT OCCUR UNTIL
FARTHER TO OUR EAST. THIS TRANSLATES TO THE SRN STREAM UPR LOW
STAYING FAR ENUF SOUTH SUCH THAT ANY ACCUMULATING SNOW WOULD ONLY
REACH FAR SRN WI AT BEST. STILL EXPECT TO SEE SOME CLOUDS TO
INCREASE OVER THE SE HALF OF THE FCST AREA ON TUE...BUT NON POPS
WL BE NEEDED.
WHILE THE SRN STREAM SYSTEM CONTS TO LIFT NE INTO THE OHIO RIVER
VALLEY TUE NGT...THE TRAILING NRN STREAM SHRTWV TROF MOVES THRU
THE WRN GREAT LKS AND SENDS A CDFNT THRU WI. ONCE AGAIN...BETTER
FORCING GOES EITHER NORTH OR SOUTH OF WI...THUS A CONTINUATION OF
A DRY FCST. A WEAK SFC RDG IS THEN FCST TO MOVE ACROSS MAINLY THE
SRN SECTIONS OF THE GREAT LKS LATER TUE NGT INTO WED. UNDER MOSTLY
CLEAR TO PARTLY CLDY SKIES...LOOK FOR TEMPS TO REMAIN WELL ABV
NORMAL.
FCST BECOME MORE MUDDLED FOR THE LATTER PART OF THE WORK WEEK AS
THE NXT SIGNIFICANT NRN STREAM SHRTWV ENERGY DROPS SE INTO THE
GREAT BASIN. ISSUES AMONG THE MDLS CENTER ON WHETHER THIS ENERGY
WL CLOSE OFF TO ANOTHER CLOSED UPR LOW OR PROGRESS EAST WITH TIME
AND INCREASE SNOW CHCS ACROSS WI. A PROGRESSIVE SOLN WOULD BRING A
LGT SNOW POTENTIAL TO NE WI BY THU NGT INTO FRI...BUT WITH ALL THE
UNCERTAINTY INVOLVED AT THIS TIME...HAVE GONE WITH THE MDL
CONSENSUS SOLN OF ONLY SLGT CHC POPS FOR NOW.
&&
.AVIATION...FOR 12Z TAF ISSUANCE. MVFR CIGS HAVE WORKED INTO GRB
OFF THE BAY. THAT WL PERSIST AS FLOW STAYS NE FOR A TIME...BUT LOW
CLDS SHOULD MOVE BACK OUT LATER. THEN EXPECT A BAND OF IFR
CONDITIONS...PRIMARILY DUE TO VSBYS...TO SWEEP ACRS THE NE 1/2 OF
THE FCST AREA THIS AFTN.
&&
.GRB WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SKOWRONSKI/KALLAS
AREA FORECAST DISCUSSION
NWS NEW YORK NY
431 AM EST MON DEC 19 2011
.SYNOPSIS...
A HIGH PRESSURE RIDGE SHIFTS OFFSHORE TODAY. A COLD FRONT WILL
MOVE THROUGH TONIGHT. HIGH PRESSURE BUILDS OVER THE AREA TUESDAY. A
WARM FRONT APPROACHES FROM THE SOUTH TUESDAY NIGHT...THEN LIFTS TO
THE NORTH WEDNESDAY...FOLLOWED BY A COLD FRONT WEDNESDAY
NIGHT...AS AN AREA OF LOW PRESSURE PASSES TO OUR NORTH. HIGH
PRESSURE THEN BUILDS IN TO OUR NORTH THURSDAY THROUGH SUNDAY...AS
A COUPLE OF LOW PRESSURE SYSTEMS PASS TO OUR SOUTH FRIDAY AND THEN
LATE NEXT WEEKEND.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
A HIGH PRESSURE RIDGE LOCATED RIGHT ALONG THE EAST COAST EARLY THIS
MORNING WILL SHIFT OFFSHORE TODAY...ALLOWING RETURN FLOW TO DEVELOP
OVER THE REGION. LOW PRESSURE EMBEDDED IN A STRONG JETSTREAM ACROSS
SOUTHERN CANADA WILL QUICKLY SHIFT EASTWARD ACROSS QUEBEC...DRAGGING
A COLD FRONT ACROSS THE GREAT LAKES REGION. THE PRESSURE GRADIENT
WILL INCREASE QUICKLY TODAY AS THE LOW PASSES TO OUR NORTH...WITH
GUSTY WINDS DEVELOPING BY LATE MORNING AND CONTINUING THROUGH THE
AFTERNOON. 00Z NAM SUGGESTS LIGHT PRECIP DEVELOPING OVER THE REGION
BY LATE AFTERNOON WITH A WEAK VORT MAX MOVING THROUGH...BUT SIDED
WITH 00Z GFS/ECMWF WHICH KEEP ANY PRECIP NORTH AND WEST OF THE
REGION.
WARM AIR ADVECTION DEVELOPS WITH THE HIGH OFFSHORE...ENABLING
TEMPERATURES TO CLIMB INTO THE LOW TO MID 40S AREA WIDE. MAV/MET
GUIDANCE IN GOOD AGREEMENT...AND WERE BLENDED FOR TEMPS.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH TUESDAY NIGHT/...
MODEL CONSENSUS INDICATES COLD FRONT WILL BE LOCATED OVER
WESTERN/NORTHERN NY STATE BY EARLY THIS EVENING...THEN QUICKLY SWEEP
TO THE SOUTHEAST AND MOVE THROUGH THE REGION OVERNIGHT. WITH ZONAL
FLOW ALOFT MOISTURE WILL BE LIMITED...BUT ENOUGH LAKE MOISTURE MAY
ALLOW FOR SOME SPRINKLES AND/OR FLURRIES...WITH POTENTIAL FOR LIGHT
SNOW OVER THE LOWER HUDSON VALLEY. BL TOO WARM FOR FLAKES NEAR THE
COASTS INITIALLY...BUT AS THE CWA GETS INTO THE RR QUAD OF THE H3
150 PLUS KT H3 JET AFT MIDNIGHT...A FEW FLURRIES MAY MIX IN WITH
ANY SPRINKLES HERE AS WELL.
GUSTY WINDS DIMINISH THIS EVENING AS LOW-LEVEL INVERSION
DEVELOPS...BUT GUSTS MAY REDEVELOP BY EARLY TUESDAY MORNING AS
COOLER AIR ALOFT MOVES IN BEHIND THE FRONT.
MAV/MET BLENDED AGAIN FOR LOWS TONIGHT...WHICH WILL RANGE FROM THE
UPPER 20S OVER NORTHERN SECTIONS TO THE MID 30S NEAR THE COASTS.
ON TUESDAY...HIGH PRESSURE RIDGE DROPS FROM THE GREAT LAKES INTO
THE TRI-STATE AREA. WINDS DIMINISH AS THE HIGH BUILDS IN. HIGHS
GENERALLY IN THE LOW TO MID 40S.
&&
.LONG TERM /WEDNESDAY THROUGH SUNDAY/...
A PROGRESSIVE SPLIT FLOW ACROSS THE LOWER 48 GETS A BIT MORE
INTERESTING THIS WEEK AS SEVERAL SOUTHERN BRANCH LOWS INTERACT WITH
MARGINALLY COLD AIR ACROSS THE NE U.S. THE 00Z GFS AND ECMWF ARE IN
REMARKABLE AGREEMENT DURING THIS PERIOD...ALTHOUGH THERE ARE SOME
TIMING DIFFERENCES AS CAN BE EXPECTED. THE GFS IS THE MORE
PROGRESSIVE OF THE SOLUTIONS IN THE HANDLING OF EACH WAVE...WHICH
SEEMS TO MAKE SENSE BASED ON THE PROGRESSIVE NATURE OF THE UPPER
FLOW. AT THIS POINT IN TIME...IT IS TOO EARLY BE SPECIFIC WITH ANY
DETAILS...BUT THERE IS THE POTENTIAL FOR WINTRY WEATHER...
ESPECIALLY ACROSS THE INTERIOR.
THE FIRST STORM SYSTEM WILL EMERGE FROM THE MID MS VALLEY TUE NIGHT
AND TAKE A TRACK TO THE NORTH AND WEST OF THE FORECAST AREA WED.
PCPN AHEAD OF ITS WARM FRONT MAY DEVELOP IN THE OVERNIGHT HOUR TUE.
THE TIMING HERE IS CRITICAL AS THE COLD AIR WILL BE ERODING IN A
STRENGTHENING SOUTHERLY FLOW. COASTAL AREAS WILL BE ALL RAIN...BUT
THERE IS A POSSIBILITY OF A BRIEF WINTRY MIX ACROSS INLAND AREAS
PRIOR TO DAYBREAK. THE STEADIEST PCPN WILL FALL AS RAIN ON WED. THE
TRAILING COLD FRONT WILL THEN BRIEFLY DRY CONDITIONS OUT WED NIGHT
INTO THU. THE NEXT SYSTEM TAKES A TRACK FROM THE LOWER MS VALLEY
THU...NE TO OFF THE MID ATLANTIC COAST ON FRI. THIS SYSTEM TOO MAY
FEATURE A WINTRY MIX INLAND. VERTICAL TEMPERATURE PROFILES ARE
MARGINAL IN BOTH CASES WITH NO REAL GOOD SOURCE OF POLAR AIR. THE
FAST FLOW ACROSS THE NORTHERN TIER OF THE COUNTRY IS PREVENTING A
STRONG SOUTHWARD PUSH.
FINALLY...THE LAST STORM HAS THE POTENTIAL TO IMPACT THE AREA
CHRISTMAS EVE AND DAY. THE ECMWF HAS TRENDED TO A STRONGER LOW IN
COMPARISON TO THE GFS WITH A 989 MB LOW PASSING NEAR CAPE COD NEXT
SUNDAY. THE GFS IS ABOUT 20 MB WEAKER. A DECENT HIGH TO THE NORTH
FOR THIS GO AROUND MAY POSE A MORE SIGNIFICANT WINTER WEATHER
THREAT. ONCE AGAIN THOUGH...THERE WILL LIKELY BE SEVERAL CHANGES IN
THE FORECAST OUT THIS FAR. IT IS DEFINITELY WORTH KEEPING AN EYE ON.
TEMPERATURES WILL START OFF ABOVE NORMAL FOR THE MID WEEK
PERIOD...BUT THEN TRANSITION TO MORE SEASONABLE READINGS FOR THE END
OF THE WEEK INTO NEXT WEEKEND. HIGHS WILL TOP OUT IN THE LOWER 50S
WED AND THU...BUT THEN FALL TO AROUND 40 BY THE WEEKEND.
&&
.AVIATION /09Z MONDAY THROUGH FRIDAY/...
HIGH PRESSURE OVER THE AREA DRIFTS SOUTH AS A COLD FRONT APPROACHES.
THE FRONT MOVES THROUGH THE TERMINALS LATE TONIGHT.
VFR. LIGHT AND VARIABLE WINDS EARLY THIS MORNING BECOME SOUTHWEST
AND INCREASE AS THE DAY PROGRESSES WITH A TIGHTENING PRESSURE
GRADIENT. GUSTS DEVELOP AFTER 15Z MONDAY AND PEAK IN THE EARLY TO MID
AFTERNOON 20 TO 25 KT.
...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)
KJFK FCSTER COMMENTS: GUSTS MAY BEGIN AN HOUR ON EITHER SIDE OF
15Z AND MAY BE A FEW KT HIGHER THAN FORECAST AFT 18Z. GUSTS MAY
LINGER THROUGH 03Z WHILE DIMINISHING.
KLGA FCSTER COMMENTS: GUSTS MAY BEGIN AN HOUR ON EITHER SIDE OF
15Z AND MAY BE A FEW KT HIGHER THAN FORECAST AFT 18Z. GUSTS MAY
LINGER THROUGH 03Z WHILE DIMINISHING.
KEWR FCSTER COMMENTS: GUSTS MAY BEGIN AN HOUR ON EITHER SIDE OF
15Z AND MAY BE A FEW KT HIGHER THAN FORECAST AFT 18Z. GUSTS MAY
LINGER THROUGH 03Z WHILE DIMINISHING.
KTEB FCSTER COMMENTS: GUSTS MAY BEGIN AN HOUR ON EITHER SIDE OF
15Z AND MAY BE A FEW KT HIGHER THAN FORECAST AFT 18Z. GUSTS MAY
LINGER UNTIL AROUND 00Z WHILE DIMINISHING.
KHPN FCSTER COMMENTS: GUSTS MAY BEGIN AN HOUR ON EITHER SIDE OF
15Z AND MAY BE A FEW KT HIGHER THAN FORECAST AFT 18Z. GUSTS MAY
LINGER UNTIL AROUND 00Z WHILE DIMINISHING.
KISP FCSTER COMMENTS: GUSTS MAY BEGIN AN HOUR ON EITHER SIDE OF
15Z AND MAY BE A FEW KT HIGHER THAN FORECAST AFT 18Z. GUSTS MAY
LINGER UNTIL AROUND 00Z WHILE DIMINISHING.
OUTLOOK FOR 06Z TUESDAY THROUGH FRIDAY...
MON NIGHT...VFR. W WINDS BECMG NW BEHIND A COLD FRONT.
FLURRIES/SPRINKLES POSSIBLE.
TUE...VFR.
TUE NIGHT AND WED...SUB VFR IN RAIN...A WINTRY MIX POSSIBLE
INLAND TUE NIGHT. BECOMING VFR WED NIGHT.
THU...VFR.
FRI...SUB-VFR POSSIBLE.
&&
.MARINE...
ISSUED GALE WARNING FOR EASTERN TWO OCEAN ZONES BEGINNING LATE
THIS MORNING AS CONFIDENCE INCREASES THAT GALE GUSTS WILL DEVELOP.
WINDS START LIGHT FROM THE SW THIS MORNING...BUT THE PRESSURE
GRADIENT WILL INCREASE QUICKLY AS HIGH PRESSURE MOVES EAST OF THE
WATERS AND A COLD FRONT APPROACHES FROM THE NORTHWEST. SCA
CONTINUES FOR ALL OTHER ZONES. ALSO CAN`T RULE OUT POTENTIAL FOR A
FEW GALE-FORCE GUSTS IN EASTERN LONG ISLAND SOUND AND THE WESTERN
OCEAN WATERS TODAY...AND THESE AREAS WILL NEED TO BE MONITORED.
OTHERWISE SCA CONTINUES OVER ALL WATERS NOT COVERED BY THE GALE
WARNING.
WINDS DIMINISH LATE TONIGHT BEHIND THE COLD FRONT AS HIGH PRESSURE
APPROACHES THE WATERS. SCA-LEVEL SEAS COULD LINGER INTO TUESDAY
ON THE FAR EASTERN COASTAL WATERS...OTHERWISE SUB-SCA CONDITIONS
ARE EXPECTED TUESDAY AND TUESDAY NIGHT.
THERE WILL BE POTENTIAL EPISODES OF SCA CONDITIONS THROUGHOUT THE
WEEK AS A SERIES OF LOWS IMPACT THE WATERS. THE FIRST OF WHICH WILL
SEND A COLD FRONT ACROSS THE AREA WED NIGHT WITH A STRONG WLY FLOW
ON THE BACKSIDE INTO THU MORNING. HIGH PRESSURE THEN BRIEFLY RETURNS
TO THE WATERS ON THU BEFORE LOW PRESSURE PASSES TO THE SOUTH ON FRI.
FOR NOW GOING WITH SUB-SCA CONDITIONS ON FRIDAY WITH THE COASTAL LOW
PASSING TO THE SOUTH...BUT THERE IS MUCH UNCERTAINTY IN THIS
&&
.HYDROLOGY...
TRACE AMOUNTS OF PCPN ARE POSSIBLE TONIGHT.
THERE IS THE POTENTIAL FOR AROUND A 1/4 TO 1/2 AN INCH OF LIQUID
EQUIVALENT TO FALL OVER THE REGION FROM TUESDAY NIGHT INTO WEDNESDAY
NIGHT. SOME OF THIS COULD FALL AS FROZEN PRECIPITATION ACROSS
MAINLY NORTHERN INTERIOR ZONES INTO WEDNESDAY MORNING. NO
SIGNIFICANT HYDROLOGIC IMPACT IS CURRENTLY EXPECTED.
ADDITIONAL PRECIPITATION IS EXPECTED FROM A SERIES OF LOW
PRESSURE SYSTEMS THAT WILL IMPACT THE AREA LATE IN THE WEEK AND
THE WEEKEND. NO SIGNIFICANT HYDROLOGICAL IMPACTS ARE ANTICIPATED
AT THIS TIME.
&&
.OKX WATCHES/WARNINGS/ADVISORIES...
CT...NONE.
NY...NONE.
NJ...NONE.
MARINE...SMALL CRAFT ADVISORY FROM 10 AM THIS MORNING TO 1 AM EST
TUESDAY FOR ANZ330-335-338-340-345-355.
GALE WARNING FROM 10 AM THIS MORNING TO 1 AM EST TUESDAY FOR
ANZ350-353.
&&
$$
SYNOPSIS...KCS/DW
NEAR TERM...KCS
SHORT TERM...KCS
LONG TERM...DW
AVIATION...24
MARINE...KCS/DW
HYDROLOGY...KCS/DW
AREA FORECAST DISCUSSION
NWS NEW YORK NY
1259 AM EST MON DEC 19 2011
.SYNOPSIS...
A HIGH PRESSURE RIDGE WILL DRIFT OVER THE REGION TONIGHT...AND
OFFSHORE ON MONDAY. A COLD FRONT WILL PASS MONDAY NIGHT. HIGH
PRESSURE BUILDS OVER THE AREA TUESDAY. A WARM FRONT APPROACHES
FROM THE SOUTH TUESDAY NIGHT...THEN LIFTS TO THE NORTH
WEDNESDAY...FOLLOWED BY A COLD FRONT WEDNESDAY NIGHT...AS AN AREA
OF LOW PRESSURE PASSES TO OUR NORTH. HIGH PRESSURE THEN BUILDS IN
TO OUR NORTH THURSDAY THROUGH SUNDAY...AS A COUPLE OF LOW PRESSURE
SYSTEMS PASS TO OUR SOUTH FRIDAY AND THEN LATE NEXT WEEKEND.
&&
.NEAR TERM /UNTIL 6 AM THIS MORNING/...
HIGH PRESSURE CURRENTLY ALONG THE EAST COAST WILL CONTINUE TO
TRANSLATE SOUTH AND EAST EARLY THIS MORNING. SOME OBS IN CENTRAL
NJ REPORTING LIGHT SW WINDS...INDICATING SW FLOW WILL DEVELOP OVER
THE NEXT FEW HOURS. HIGH AND MID LEVEL CLOUDS OVER UPSTATE NY ARE
MOVING TOWARDS THE AREA BUT DUE TO THE DRY AIR IN PLACE...ONLY
HIGH CLOUDS EXPECTED EARLY THIS MORNING.
TEMP FORECAST ON TRACK WITH JUST MINOR ADJUSTMENTS MADE AT 0530Z. WITH
A SW FLOW BUILDING IN BEHIND THE HIGH PRESSURE EARLY MONDAY
MORNING...TEMPERATURES IN THE NYC METRO AREA AND ON LONG ISLAND
COULD EXPERIENCE A QUICKER WARMING THAN OTHER AREAS.
&&
.SHORT TERM /6 AM THIS MORNING THROUGH TUESDAY NIGHT/...
LOW PRES OVER ONTARIO WILL RACE EWD ON MON UNDER THE INFLUENCE OF
A STRENGTHENING 120KT H3 JET. AS THE ASSOCIATED COLD FRONT
APPROACHES...THE PRES GRAD WILL TIGHTEN...ALLOWING FOR INCREASING
WSW WINDS DURING THE DAY. SUSTAINED WINDS WILL MAX OUT IN THE
15-20KT RANGE WITH SOME GUSTS TO AROUND 30KT. STRONGEST WINDS WILL
BE ALONG THE S SHORES. 12Z OKX SOUNDING INDICATED 0.14 INCHES OF
PW...SO THE FCST WILL BE KEPT DRY DURING THE DAYTIME HOURS WITH
MOISTURE TRANSPORT VECTORS NOT REACHING THE CWA TIL AROUND 00Z
TUE. TEMPS WARMER THAN SUN DUE TO BETTER MIXING ALL AREAS AND AN
ONSHORE COMPONENT ON THE COASTS.
THE COLD FRONT PASSES MON NGT. 12Z MODELS IN GOOD AGREEMENT WITH
THIS. MOISTURE REMAINS EXTREMELY LIMITED...BUT ENOUGH LAKE MOISTURE
MAY ALLOW FOR A FEW SPRINKLES AND/OR FLURRIES. HAVE RETAINED THIS
WEATHER IN THE GRIDS. BL TOO WARM FOR FLAKES NEAR THE COASTS
INITIALLY...BUT AT THE CWA GETS INTO THE RR QUAD OF THE H3 170 PLUS
KT H3 JET AFT MIDNIGHT...A FEW FLURRIES POSSIBLE POST FRONTAL ACROSS
ALL AREAS. MOS WAS IN GOOD AGREEMENT FOR TEMPS...SO A BLEND WAS
USED.
&&
.LONG TERM /WEDNESDAY THROUGH SUNDAY/...
THE GFS IS MORE PROGRESSIVE THAN THE NAM/ECMWF/SREF WITH THE SYSTEM
IMPACTING THE REGION MID WEEK...AS IS ITS BIAS...SO USED A BLEND OF
THE SLOWER SOLUTIONS TUESDAY THROUGH WEDNESDAY. WEDNESDAY NIGHT
THROUGH CHRISTMAS DAY...THERE ARE QUITE A BIT OF DIFFERENCES BETWEEN
THE GFS AND ECMWF IN HOW THEY HANDLE THE NEXT SYSTEM EJECTING FROM
THE SW U.S. AND ITS INTERACTION WITH THE NORTHERN STREAM. DUE TO
BETTER RUN TO RUN CONSISTENCY AND BETTER OVERALL VERIFICATION IN THE
LONG TERM...LEANED HEAVILY TOWARDS THE ECMWF WEDNESDAY NIGHT THROUGH
SUNDAY.
RIDGING BUILDS INTO THE AREA TUESDAY/TUESDAY NIGHT...THEN SLIDES
OFFSHORE WEDNESDAY AS A SOUTHERN STREAM TROUGH LIFTS INTO THE UPPER
OHIO RIVER VALLEY...THIS TROUGH WILL SUPPORT A SURFACE LOW TRACKING
TO OUR NORTH WEDNESDAY.
TUESDAY SHOULD BE DRY UNDERNEATH THE RIDGE BUILDING IN. OVER RUNNING
SETS UP TUESDAY NIGHT...AHEAD OF A SURFACE AND 850 HPA WARM
FRONT...EXPECT LIGHT PRECIPITATION TO GRADUALLY DEVELOP FROM SW TO
NE FROM TUESDAY NIGHT INTO WEDNESDAY MORNING. LOW LEVEL THERMAL
PROFILES SUPPORT RAIN ACROSS NYC METRO/LONG ISLAND WITH A WINTRY
MIX...INCLUDING POSSIBLY SOME FREEZING RAIN ACROSS THE
INTERIOR...BEFORE CHANGING TO ALL RAIN AS THE WARM FRONT LIFTS TO
THE NORTH WEDNESDAY MORNING. 40-50 KT LOW LEVEL JET MOVES IN BY
WEDNESDAY AFTERNOON SUPPORTING MORE WIDESPREAD RAIN.
THE AFOREMENTIONED TROUGH LIFT JUST OVER THE REGION WEDNESDAY
NIGHT...ALLOWING PRECIPITATION TO TAPER OFF FROM W TO E BY THURSDAY
MORNING - STILL CARRY SLIGHT CHANCE POPS THURSDAY MORNING AS THERE
HAS BEEN SOME UNCERTAINTY IN TIMING OF THE SYSTEM...WITH SOME
SUGGESTIONS IT COULD END UP A TAD SLOWER THAN CURRENTLY FORECAST.
RIDGING BUILDS IN THURSDAY WITH ITS AXIS SLIDING OFFSHORE THURSDAY
NIGHT. FOLLOWING THE ECMWF...IT APPEARS THAT THE SHEARING TROUGH
FORECAST TO LIFT OUT OF BAJA CA WEDNESDAY...APPROACHES BY LATE
THURSDAY NIGHT...THEN CROSSES ON FRIDAY...WITH AN ASSOCIATED
COASTAL LOW PASSING TO THE SOUTH ALONG A STALLED FRONTAL BOUNDARY.
LOW LEVEL THERMAL PROFILES SUGGEST SNOW OR RAIN/SNOW ACROSS NORTHERN
ZONES AND RAIN ACROSS SOUTHERN ZONES BY LATE THURSDAY NIGHT...WITH
PRECIPITATION TRANSITIONING TO ALL RAIN DURING THE DAY ON FRIDAY ON
THE NORTHERN TIER. THERE IS QUITE A BIT OF UNCERTAINTY WITH THIS
SYSTEM...WITH SOME POTENTIAL IT COULD END UP MISSING US ENTIRELY TO
THE SOUTH.
FRIDAY NIGHT AND SATURDAY WILL FEATURE SW FLOW ALOFT...WITH SOME
EMBEDDED SHORTWAVES. THESE WARRANT SLIGHT CHANCE POPS FOR NOW...BUT
MORE THAN LIKELY WILL BE DRY.
THE NEXT POTENTIAL SYSTEM IMPACTS THE REGION LATE CHRISTMAS
EVE/CHRISTMAS DAY...THIS TIME EJECTING FROM NEAR THE FOUR CORNERS
REGION AROUND THURSDAY. LIKE THE SYSTEM FOR FRIDAY...THE SURFACE LOW
WILL TRACK TO THE SOUTH...THE QUESTION IS HOW FAR. FOLLOWING THE
ECMWF...HAVE SLIGHT CHANCE POPS FOR LIGHT SNOW DEVELOPING ACROSS
MOST ZONES LATE SATURDAY NIGHT...AND CONTINUING INTO SUNDAY
MORNING...THEN CHANGING TO RAIN IN THE AFTERNOON. ONCE AGAIN - LOW
CONFIDENCE AT THIS TIME.
NEAR NORMAL TEMPERATURES ARE EXPECTED TUESDAY...THEN ABOVE NORMAL
TEMPERATURES TUESDAY NIGHT THROUGH THURSDAY NIGHT. NEAR NORMAL
TEMPERATURES ARE FORECAST FRIDAY-SUNDAY.
&&
.AVIATION /06Z MONDAY THROUGH FRIDAY/...
HIGH PRESSURE OVER THE AREA DRIFTS SOUTH AS A COLD FRONT APPROACHES.
THE FRONT MOVES THROUGH THE TERMINALS LATE MONDAY NIGHT.
VFR. LIGHT AND VARIABLE WINDS BECOME SOUTHWEST LATE. GUSTS DEVELOP
AFTER 15Z MONDAY AND PEAK IN THE EARLY TO MID AFTERNOON 20 TO 25 KT.
OUTLOOK FOR 06Z TUESDAY THROUGH FRIDAY...
MONDAY NIGHT...VFR. WEST WINDS SHIFT TO NORTHWEST BEHIND A COLD
FRONT.
TUESDAY...VFR.
TUESDAY NIGHT AND WEDNESDAY...SUB VFR IN RAIN...A WINTRY MIX
POSSIBLE INLAND LATE TUESDAY NIGHT. BECOMING VFR WEDNESDAY NIGHT.
THURSDAY...VFR.
FRIDAY...SUB-VFR POSSIBLE.
&&
.MARINE...
LIGHT WINDS TNGT AS HIGH PRES BUILDS OVER THE WATERS. THE HIGH
DRIFTS E OF THE CSTL WATERS MON...ALLOWING FOR A TIGHTENING PRES
GRAD TO DEVELOP THRU THE DAY AS A COLD FRONT APPROACHES FROM THE W.
STRENGTHENING WSW WINDS WILL BE THE RESULT. SCA WILL REMAIN IN
EFFECT FOR ALL WATERS EXCEPT FOR THE ERN OCEAN...WHERE THE GALE
WATCH WILL BE RETAINED. WINDS WEAKEN INVOF THE FRONT
OVERNIGHT...THEN VEER TO THE NW BEHIND THE FRONT EARLY TUE MRNG.
SCA LEVEL SEAS COULD LINGER INTO TUESDAY ON THE FAR EASTERN COASTAL
WATERS...OTHERWISE SUB-SCA CONDITIONS ARE EXPECTED TUESDAY AND
TUESDAY NIGHT. SOUTHERLY FLOW AHEAD OF A STORM SYSTEM
WEDNESDAY...SHOULD AT LEAST BUILD SEAS ON THE COASTAL OCEAN WATERS
TO SCA LEVELS...WITH GUSTY WINDS CONTINUING THEM AT SCA LEVELS INTO
THURSDAY. THERE IS SOME POTENTIAL FOR SCA LEVEL GUSTS ON ALL WATERS
WEDNESDAY-THURSDAY...BUT NOT QUITE CONFIDENT ENOUGH TO GO WITH THIS
IN THE FORECAST AT THIS TIME.
FOR NOW GOING WITH SUB-SCA CONDITIONS ON FRIDAY WITH A COASTAL LOW
PASSING TO THE SOUTH...BUT THERE IS MUCH UNCERTAINTY IN THIS.
&&
.HYDROLOGY...
TRACE AMOUNTS OF PCPN ARE POSSIBLE MON NGT.
THERE IS THE POTENTIAL FOR AROUND A 1/4 TO 1/2 AN INCH OF LIQUID
EQUIVALENT TO FALL OVER THE REGION FROM TUESDAY NIGHT INTO WEDNESDAY
NIGHT. SOME OF THIS SHOULD FALL AS FROZEN PRECIPITATION ACROSS
MAINLY NORTHERN INTERIOR ZONES INTO WEDNESDAY MORNING. NO
SIGNIFICANT HYDROLOGIC IMPACT IS CURRENTLY EXPECTED.
&&
.OKX WATCHES/WARNINGS/ADVISORIES...
CT...NONE.
NY...NONE.
NJ...NONE.
MARINE...SMALL CRAFT ADVISORY FROM 10 AM THIS MORNING TO 1 AM EST
TUESDAY FOR ANZ330-335-338-340-345-355.
GALE WATCH FROM 10 AM EST THIS MORNING THROUGH LATE TONIGHT
FOR ANZ350-353.
&&
$$
SYNOPSIS...JMC/MALOIT
NEAR TERM...KCS
SHORT TERM...JMC/LN
LONG TERM...MALOIT
AVIATION...MET
MARINE...JMC/MALOIT
HYDROLOGY...JMC/MALOIT
AREA FORECAST DISCUSSION
NWS NEW YORK NY
1230 AM EST MON DEC 19 2011
.SYNOPSIS...
A HIGH PRESSURE RIDGE WILL DRIFT OVER THE REGION TONIGHT...AND
OFFSHORE ON MONDAY. A COLD FRONT WILL PASS MONDAY NIGHT. HIGH
PRESSURE BUILDS OVER THE AREA TUESDAY. A WARM FRONT APPROACHES
FROM THE SOUTH TUESDAY NIGHT...THEN LIFTS TO THE NORTH
WEDNESDAY...FOLLOWED BY A COLD FRONT WEDNESDAY NIGHT...AS AN AREA
OF LOW PRESSURE PASSES TO OUR NORTH. HIGH PRESSURE THEN BUILDS IN
TO OUR NORTH THURSDAY THROUGH SUNDAY...AS A COUPLE OF LOW PRESSURE
SYSTEMS PASS TO OUR SOUTH FRIDAY AND THEN LATE NEXT WEEKEND.
&&
.NEAR TERM /UNTIL 6 AM THIS MORNING/...
HIGH PRESSURE CURRENTLY OVER THE VIRGINIA COAST WILL CONTINUE TO
TRANSLATE SOUTH AND EAST OVERNIGHT. WINDS ARE CALM IN MOST
LOCATIONS WITH TEMPERATURES ALREADY IN THE TEENS TO AROUND 30 IN
THE NYC METRO AREA. DRY AIR STILL IN PLACE OVER THE AREA WITH THE
LATEST SOUNDING SHOWING PW OF 0.09 IN. HIGH AND MID LEVEL CLOUDS
OVER UPSTATE NY ARE MOVING TOWARDS THE AREA BUT DUE TO THE DRY AIR
IN PLACE...ONLY HIGH CLOUDS EXPECTED OVERNIGHT AND ARE ALREADY
MOVING IN AS OF 02Z OBS.
HAVE UPDATED TEMPERATURES AND DEW POINTS TO REFLECT THE CURRENT
CONDITIONS. WITH A SW FLOW BUILDING IN BEHIND THE HIGH PRESSURE
EARLY MONDAY MORNING...TEMPERATURES IN THE NYC METRO AREA AND ON
LONG ISLAND COULD EXPERIENCE A QUICKER WARMING THAN OTHER AREAS.
&&
.SHORT TERM /6 AM THIS MORNING THROUGH TUESDAY NIGHT/...
LOW PRES OVER ONTARIO WILL RACE EWD ON MON UNDER THE INFLUENCE OF
A STRENGTHENING 120KT H3 JET. AS THE ASSOCIATED COLD FRONT
APPROACHES...THE PRES GRAD WILL TIGHTEN...ALLOWING FOR INCREASING
WSW WINDS DURING THE DAY. SUSTAINED WINDS WILL MAX OUT IN THE
15-20KT RANGE WITH SOME GUSTS TO AROUND 30KT. STRONGEST WINDS WILL
BE ALONG THE S SHORES. 12Z OKX SOUNDING INDICATED 0.14 INCHES OF
PW...SO THE FCST WILL BE KEPT DRY DURING THE DAYTIME HOURS WITH
MOISTURE TRANSPORT VECTORS NOT REACHING THE CWA TIL AROUND 00Z
TUE. TEMPS WARMER THAN SUN DUE TO BETTER MIXING ALL AREAS AND AN
ONSHORE COMPONENT ON THE COASTS.
THE COLD FRONT PASSES MON NGT. 12Z MODELS IN GOOD AGREEMENT WITH
THIS. MOISTURE REMAINS EXTREMELY LIMITED...BUT ENOUGH LAKE MOISTURE
MAY ALLOW FOR A FEW SPRINKLES AND/OR FLURRIES. HAVE RETAINED THIS
WEATHER IN THE GRIDS. BL TOO WARM FOR FLAKES NEAR THE COASTS
INITIALLY...BUT AT THE CWA GETS INTO THE RR QUAD OF THE H3 170 PLUS
KT H3 JET AFT MIDNIGHT...A FEW FLURRIES POSSIBLE POST FRONTAL ACROSS
ALL AREAS. MOS WAS IN GOOD AGREEMENT FOR TEMPS...SO A BLEND WAS
USED.
&&
.LONG TERM /WEDNESDAY THROUGH SUNDAY/...
THE GFS IS MORE PROGRESSIVE THAN THE NAM/ECMWF/SREF WITH THE SYSTEM
IMPACTING THE REGION MID WEEK...AS IS ITS BIAS...SO USED A BLEND OF
THE SLOWER SOLUTIONS TUESDAY THROUGH WEDNESDAY. WEDNESDAY NIGHT
THROUGH CHRISTMAS DAY...THERE ARE QUITE A BIT OF DIFFERENCES BETWEEN
THE GFS AND ECMWF IN HOW THEY HANDLE THE NEXT SYSTEM EJECTING FROM
THE SW U.S. AND ITS INTERACTION WITH THE NORTHERN STREAM. DUE TO
BETTER RUN TO RUN CONSISTENCY AND BETTER OVERALL VERIFICATION IN THE
LONG TERM...LEANED HEAVILY TOWARDS THE ECMWF WEDNESDAY NIGHT THROUGH
SUNDAY.
RIDGING BUILDS INTO THE AREA TUESDAY/TUESDAY NIGHT...THEN SLIDES
OFFSHORE WEDNESDAY AS A SOUTHERN STREAM TROUGH LIFTS INTO THE UPPER
OHIO RIVER VALLEY...THIS TROUGH WILL SUPPORT A SURFACE LOW TRACKING
TO OUR NORTH WEDNESDAY.
TUESDAY SHOULD BE DRY UNDERNEATH THE RIDGE BUILDING IN. OVER RUNNING
SETS UP TUESDAY NIGHT...AHEAD OF A SURFACE AND 850 HPA WARM
FRONT...EXPECT LIGHT PRECIPITATION TO GRADUALLY DEVELOP FROM SW TO
NE FROM TUESDAY NIGHT INTO WEDNESDAY MORNING. LOW LEVEL THERMAL
PROFILES SUPPORT RAIN ACROSS NYC METRO/LONG ISLAND WITH A WINTRY
MIX...INCLUDING POSSIBLY SOME FREEZING RAIN ACROSS THE
INTERIOR...BEFORE CHANGING TO ALL RAIN AS THE WARM FRONT LIFTS TO
THE NORTH WEDNESDAY MORNING. 40-50 KT LOW LEVEL JET MOVES IN BY
WEDNESDAY AFTERNOON SUPPORTING MORE WIDESPREAD RAIN.
THE AFOREMENTIONED TROUGH LIFT JUST OVER THE REGION WEDNESDAY
NIGHT...ALLOWING PRECIPITATION TO TAPER OFF FROM W TO E BY THURSDAY
MORNING - STILL CARRY SLIGHT CHANCE POPS THURSDAY MORNING AS THERE
HAS BEEN SOME UNCERTAINTY IN TIMING OF THE SYSTEM...WITH SOME
SUGGESTIONS IT COULD END UP A TAD SLOWER THAN CURRENTLY FORECAST.
RIDGING BUILDS IN THURSDAY WITH ITS AXIS SLIDING OFFSHORE THURSDAY
NIGHT. FOLLOWING THE ECMWF...IT APPEARS THAT THE SHEARING TROUGH
FORECAST TO LIFT OUT OF BAJA CA WEDNESDAY...APPROACHES BY LATE
THURSDAY NIGHT...THEN CROSSES ON FRIDAY...WITH AN ASSOCIATED
COASTAL LOW PASSING TO THE SOUTH ALONG A STALLED FRONTAL BOUNDARY.
LOW LEVEL THERMAL PROFILES SUGGEST SNOW OR RAIN/SNOW ACROSS NORTHERN
ZONES AND RAIN ACROSS SOUTHERN ZONES BY LATE THURSDAY NIGHT...WITH
PRECIPITATION TRANSITIONING TO ALL RAIN DURING THE DAY ON FRIDAY ON
THE NORTHERN TIER. THERE IS QUITE A BIT OF UNCERTAINTY WITH THIS
SYSTEM...WITH SOME POTENTIAL IT COULD END UP MISSING US ENTIRELY TO
THE SOUTH.
FRIDAY NIGHT AND SATURDAY WILL FEATURE SW FLOW ALOFT...WITH SOME
EMBEDDED SHORTWAVES. THESE WARRANT SLIGHT CHANCE POPS FOR NOW...BUT
MORE THAN LIKELY WILL BE DRY.
THE NEXT POTENTIAL SYSTEM IMPACTS THE REGION LATE CHRISTMAS
EVE/CHRISTMAS DAY...THIS TIME EJECTING FROM NEAR THE FOUR CORNERS
REGION AROUND THURSDAY. LIKE THE SYSTEM FOR FRIDAY...THE SURFACE LOW
WILL TRACK TO THE SOUTH...THE QUESTION IS HOW FAR. FOLLOWING THE
ECMWF...HAVE SLIGHT CHANCE POPS FOR LIGHT SNOW DEVELOPING ACROSS
MOST ZONES LATE SATURDAY NIGHT...AND CONTINUING INTO SUNDAY
MORNING...THEN CHANGING TO RAIN IN THE AFTERNOON. ONCE AGAIN - LOW
CONFIDENCE AT THIS TIME.
NEAR NORMAL TEMPERATURES ARE EXPECTED TUESDAY...THEN ABOVE NORMAL
TEMPERATURES TUESDAY NIGHT THROUGH THURSDAY NIGHT. NEAR NORMAL
TEMPERATURES ARE FORECAST FRIDAY-SUNDAY.
&&
.AVIATION /06Z MONDAY THROUGH FRIDAY/...
HIGH PRESSURE OVER THE AREA DRIFTS SOUTH AS A COLD FRONT APPROACHES.
THE FRONT MOVES THROUGH THE TERMINALS LATE MONDAY NIGHT.
VFR. LIGHT AND VARIABLE WINDS BECOME SOUTHWEST LATE. GUSTS DEVELOP
AFTER 15Z MONDAY AND PEAK IN THE EARLY TO MID AFTERNOON 20 TO 25 KT.
OUTLOOK FOR 06Z TUESDAY THROUGH FRIDAY...
MONDAY NIGHT...VFR. WEST WINDS SHIFT TO NORTHWEST BEHIND A COLD
FRONT.
TUESDAY...VFR.
TUESDAY NIGHT AND WEDNESDAY...SUB VFR IN RAIN...A WINTRY MIX
POSSIBLE INLAND LATE TUESDAY NIGHT. BECOMING VFR WEDNESDAY NIGHT.
THURSDAY...VFR.
FRIDAY...SUB-VFR POSSIBLE.
&&
.MARINE...
LIGHT WINDS TNGT AS HIGH PRES BUILDS OVER THE WATERS. THE HIGH
DRIFTS E OF THE CSTL WATERS MON...ALLOWING FOR A TIGHTENING PRES
GRAD TO DEVELOP THRU THE DAY AS A COLD FRONT APPROACHES FROM THE W.
STRENGTHENING WSW WINDS WILL BE THE RESULT. SCA WILL REMAIN IN
EFFECT FOR ALL WATERS EXCEPT FOR THE ERN OCEAN...WHERE THE GALE
WATCH WILL BE RETAINED. WINDS WEAKEN INVOF THE FRONT
OVERNIGHT...THEN VEER TO THE NW BEHIND THE FRONT EARLY TUE MRNG.
SCA LEVEL SEAS COULD LINGER INTO TUESDAY ON THE FAR EASTERN COASTAL
WATERS...OTHERWISE SUB-SCA CONDITIONS ARE EXPECTED TUESDAY AND
TUESDAY NIGHT. SOUTHERLY FLOW AHEAD OF A STORM SYSTEM
WEDNESDAY...SHOULD AT LEAST BUILD SEAS ON THE COASTAL OCEAN WATERS
TO SCA LEVELS...WITH GUSTY WINDS CONTINUING THEM AT SCA LEVELS INTO
THURSDAY. THERE IS SOME POTENTIAL FOR SCA LEVEL GUSTS ON ALL WATERS
WEDNESDAY-THURSDAY...BUT NOT QUITE CONFIDENT ENOUGH TO GO WITH THIS
IN THE FORECAST AT THIS TIME.
FOR NOW GOING WITH SUB-SCA CONDITIONS ON FRIDAY WITH A COASTAL LOW
PASSING TO THE SOUTH...BUT THERE IS MUCH UNCERTAINTY IN THIS.
&&
.HYDROLOGY...
TRACE AMOUNTS OF PCPN ARE POSSIBLE MON NGT.
THERE IS THE POTENTIAL FOR AROUND A 1/4 TO 1/2 AN INCH OF LIQUID
EQUIVALENT TO FALL OVER THE REGION FROM TUESDAY NIGHT INTO WEDNESDAY
NIGHT. SOME OF THIS SHOULD FALL AS FROZEN PRECIPITATION ACROSS
MAINLY NORTHERN INTERIOR ZONES INTO WEDNESDAY MORNING. NO
SIGNIFICANT HYDROLOGIC IMPACT IS CURRENTLY EXPECTED.
&&
.OKX WATCHES/WARNINGS/ADVISORIES...
CT...NONE.
NY...NONE.
NJ...NONE.
MARINE...SMALL CRAFT ADVISORY FROM 10 AM THIS MORNING TO 1 AM EST
TUESDAY FOR ANZ330-335-338-340-345-355.
GALE WATCH FROM 10 AM EST THIS MORNING THROUGH LATE TONIGHT
FOR ANZ350-353.
&&
$$
AREA FORECAST DISCUSSION
NWS PITTSBURGH PA
408 AM EST MON DEC 19 2011
.SYNOPSIS...
A COLD FRONT WILL PUSH INTO THE OHIO VALLEY AND BECOME STATIONARY
MONDAY NIGHT AND TUESDAY...BRINGING A MIXTURE OF RAIN AND SNOW.
LOW PRESSURE MOVING ALONG THIS BOUNDARY WILL BRING RAIN TUESDAY
NIGHT AND WEDNESDAY.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
MAINLY CLEAR SKIES WILL CONTINUE THROUGH MID MORNING AS SURFACE
HIGH DEPARTS. CLOUD COVER AND PRECIPITATION PROBABILITIES WILL
INCREASE WEST TO EAST BY THIS AFTERNOON AHEAD OF A FRONTAL
BOUNDARY CROSSING THE GREAT LAKES. SOUTHWEST FLOW WILL PUSH
AFTERNOON TEMPERATURES INTO THE 40S.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH WEDNESDAY/...
LATEST MODEL RUNS CONTINUE TO SHOW SURFACE BOUNDARY BECOMING
STATIONARY ACROSS THE SOUTHERN HALF OF THE FORECAST AREA LATE
TONIGHT. TEMPERATURE PROFILES FROM BUFKIT STILL SUGGEST THAT
MUCH OF THE REGION MAINLY NORTH OF THE MASON-DIXON LINE WILL HAVE
A RAIN/SNOW MIXTURE LATE TONIGHT INTO EARLY TUESDAY MORNING. QPF
AMOUNTS WILL BE LIGHT THROUGH TUESDAY. AREAS NORTH OF PITTSBURGH
TOWARD THE I-80 CORRIDOR WILL LIKELY CHANGE TO ALL SNOW MONDAY
NIGHT BUT ANY ACCUMULATION WILL BE LESS THAN AN INCH.
PRECIPITATION WILL CHANGE TO ALL RAIN BY TUESDAY AFTERNOON AS
TEMPERATURES RISE INTO THE UPPER 30S TO MID 40S.
A SHORT WAVE TROUGH WILL MOVE NORTHEAST FROM THE SOUTHERN PLAINS
WITH ITS ASSOCIATED SURFACE LOW TRACKING ACROSS THE OHIO VALLEY
WEDNESDAY. THIS SYSTEM WILL BRING PERIODS OF RAIN TUESDAY NIGHT
THROUGH LATE WEDNESDAY.
&&
.LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/...
WEAK SURFACE RIDGE WILL GIVE A GENERALLY DRY FORECAST THURSDAY. A
WEAK DISTURBANCE WILL BRING THE CHANCE FOR SHOWERS FRIDAY WITH
ABOVE NORMAL TEMPERATURES FOLLOWED BY HIGH PRESSURE AND SEASONABLE
TEMPERATURES SATURDAY. A COLD FRONT WILL BRING A CHANCE FOR RAIN
OR SNOW SHOWERS CHRISTMAS DAY. OVERALL LONG TERM FORECAST WAS A
MODIFIED VERSION OF THE HPC GRIDS.
&&
.AVIATION /08Z MONDAY THROUGH FRIDAY/...
NOT ALOT TO CHANGE FOR THIS TAF ISSUANCE AS MODEL BUFKIT PROFILES
AND RUC DATA CONTINUE TO SUGGEST WIND SHEAR ALOFT OVERNIGHT.
MAINTAINED WIND SHEAR OF WS010/23040KT THROUGH 16Z AS VERTICAL
MIXING BEGINS TO TAKE PLACE OUT AHEAD OF THE BOUNDARY PROGGED TO
BRING PRECIP TO ALL TERMINALS STARTING AROUND 19Z. SURFACE WINDS
WILL BECOME SOUTHWEST 10-15 KTS WITH GUSTS TO 20-25 KTS BY MIDDAY
MONDAY. CURRENT LAMP AND MAV GUIDANCE SUGGESTS RESTRICTIONS WILL
START OUT AT MVFR AS THE COLD FRONT DROPS SOUTHEASTWARD.
OUTLOOK...MONDAY NIGHT THROUGH FRIDAY...
STALLING COLD FRONTAL PRECIPITATION BAND WILL CAUSE FREQUENT IFR
PERIODS MONDAY NIGHT INTO WEDNESDAY. ENSUING WINTRY MIX MAY CAUSE
ADDED THE AVIATION HAZARD OF LOW LEVEL ICING TUESDAY. COLD POOL
STRATOCUMULUS MAY PROVIDE LINGERING RESTRICTIONS, MAINLY IN THE
MVFR RANGE THURSDAY. A NORTHEAST MOVING LOW PRESSURE SYSTEM MAY
PROVIDE MIXED PRECIPITATION AND IFR RESTRICTIONS FRIDAY.
&&
.PBZ WATCHES/WARNINGS/ADVISORIES...
MD...NONE.
OH...NONE.
PA...NONE.
WV...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS PITTSBURGH PA
1256 AM EST MON DEC 19 2011
.SYNOPSIS...
A COLD FRONT WILL PUSH SOUTH AND BECOME STATIONARY OVER THE
REGION MONDAY NIGHT AND TUESDAY...BRINGING A CHANCE OF RAIN AND
SNOW. LOW PRESSURE MOVING ALONG THIS BOUNDARY WILL BRING RAIN
TUESDAY NIGHT AND WEDNESDAY.
&&
.NEAR TERM /THROUGH TODAY/...
EXPECT MAINLY CLEAR SKIES OVERNIGHT BUT LITTLE DROP IN
TEMPERATURES AS SOUTHERLY FLOW INCREASES.
MORNING SUNSHINE SHALL FADE BEHIND A CANOPY OF MID LEVEL CLOUDS
AHEAD OF A BAROCLINIC ZONE CROSSING THROUGH THE GREAT LAKES. RAIN
CHANCES WILL INCREASE BY AFTERNOON AND TEMPERATURES WILL PEAK IN
THE 40S.
&&
.SHORT TERM /TONIGHT THROUGH WEDNESDAY/...
AS COLD FRONT BECOMES STATIONARY SOUTH OF THE MASON DIXON LINE
MONDAY NIGHT MODEL PROFILES AND THICKNESS VALUES SUGGEST THAT MUCH
OF THE REGION WILL HAVE A RAIN-SNOW MIX INTO THE FIRST HALF OF
TUESDAY. AREAS NORTH OF PITTSBURGH TOWARD THE I-80 CORRIDOR WILL
BE ALL SNOW FOR A TIME BUT ANY ACCUMULATION WILL BE A COATING OR
LESS THAN AN INCH. BY TUESDAY AFTERNOON PRECIP WILL BECOME ALL
RAIN AS LOW PRESSURE MOVES ACROSS THE LOWER OHIO VALLEY. MILD
TEMPERATURES AND CONTINUED RAIN SHOWERS INTO WEDNESDAY AS THE
SURFACE LOW MOVES TO THE EASTERN GREAT LAKES AND PUSHES A WEAK
COLD FRONT ACROSS AREA BY LATE DAY.
&&
.LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/...
WEAK SURFACE RIDGE WILL GIVE A GENERALLY DRY FORECAST THURSDAY. A
WEAK DISTURBANCE WILL BRING THE CHANCE FOR SHOWERS FRIDAY WITH
ABOVE NORMAL TEMPERATURES FOLLOWED BY HIGH PRESSURE AND SEASONABLE
TEMPERATURES SATURDAY. A COLD FRONT WILL BRING A CHANCE FOR RAIN
OR SNOW SHOWERS CHRISTMAS DAY. OVERALL LONG TERM FORECAST WAS A
MODIFIED VERSION OF THE HPC GRIDS.
&&
.AVIATION /06Z MONDAY THROUGH FRIDAY/...
NOT ALOT TO CHANGE FOR THIS TAF ISSUANCE AS MODEL BUFKIT PROFILES
AND RUC DATA CONTINUE TO SUGGEST WIND SHEAR ALOFT OVERNIGHT.
MAINTAINED WIND SHEAR OF WS010/23040KT THROUGH 16Z AS VERTICAL
MIXING BEGINS TO TAKE PLACE OUT AHEAD OF THE BOUNDARY PROGGED TO
BRING PRECIP TO ALL TERMINALS STARTING AROUND 19Z. SURFACE WINDS
WILL BECOME SOUTHWEST 10-15 KTS WITH GUSTS TO 20-25 KTS BY MIDDAY
MONDAY. CURRENT LAMP AND MAV GUIDANCE SUGGESTS RESTRICTIONS WILL
START OUT AT MVFR AS THE COLD FRONT DROPS SOUTHEASTWARD.
OUTLOOK...MONDAY NIGHT THROUGH FRIDAY...
STALLING COLD FRONTAL PRECIPITATION BAND WILL CAUSE FREQUENT IFR
PERIODS MONDAY NIGHT INTO WEDNESDAY. ENSUING WINTRY MIX MAY CAUSE
ADDED THE AVIATION HAZARD OF LOW LEVEL ICING TUESDAY. COLD POOL
STRATOCUMULUS MAY PROVIDE LINGERING RESTRICTIONS, MAINLY IN THE
MVFR RANGE THURSDAY. A NORTHEAST MOVING LOW PRESSURE SYSTEM MAY
PROVIDE MIXED PRECIPITATION AND IFR RESTRICTIONS FRIDAY.
&&
.PBZ WATCHES/WARNINGS/ADVISORIES...
MD...NONE.
OH...NONE.
PA...NONE.
WV...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
407 AM EST MON DEC 19 2011
.DISCUSSION /TODAY THROUGH SUNDAY/...
997MB LOW PRESSURE SYSTEM LOCATED OVER EASTERN ONTARIO WILL CONTINUE
E INTO SRN QUEBEC THIS MORNING. COLD FRONT CURRENTLY SWEEPING
THROUGH CNTRL/ERN UPPER MI...WITH ONLY SCT CLOUDS ASSOCIATED WITH
IT/S PASSING. BEHIND THE FRONT...A LARGE AREA OF LOW CLOUDS OVER NRN
MN...SW ONTARIO AND MANITOBA WOULD INDICATE THAT MOISTURE MAY BE
BETTER THAN INDICATED BY THE 00Z NAM. 00Z GFS AND LATEST RUC RUNS
SEEM TO BE DOING A LITTLE BETTER ON PICKING UP THE LOW CLOUDS AND
WILL FOLLOW THAT FOR THE TODAY FORECAST /WHICH IS A LITTLE MORE
PESSIMISTIC/.
COLD AIR STILL LAGGING BEHIND THE FRONT...AND WITH THE AREA OF LOW
CLOUDS CURRENTLY WORKING INTO WRN UPPER MI...EXPECT SOME PCPN TO
START OVER THE NEXT COUPLE OF HOURS OVER THE UPSLOPE HIGHER TERRAIN.
H850-700 DRY AIR AND SUBSIDENCE WILL HELP KEEP INVERSION HEIGHTS AT
3KFT. DRY NEAR SFC AIR WILL KEEP CLOUD DEPTHS LIMITED /ONLY AROUND
1.5-2KFT/ SO HAVE LIMITED CONF ON MUCH PCPN OCCURRING. THIS COULD
CREATE SOME P-TYPE ISSUES INITIALLY...AS BUFKIT SOUNDINGS SHOW CLOUD
TEMPS ARE ONLY IN THE -4 TO -7C RANGE...LIMITING ICE CRYSTALS.
SHOULD BE A QUICK TRANSITION FROM W TO E THROUGH THE EARLY MORNING
HOURS WITH THE H850 TEMPS FALLING TO -11C BY 15Z. THEREFORE...WILL
CONTINUE MENTION OF DZ/FZDZ THROUGH 12Z OVER THE W AND JUST DZ
THROUGH 15Z OVER THE E DUE TO WARMER SFC TEMPS. THE COLDER H850
TEMPS WILL LIKELY LEAD TO SOME LIGHT LES DEVELOPMENT THIS
MORNING...BUT INVERSION HEIGHTS WILL LIMIT INTENSITY. WITH THE
LONGER FETCH...THINK THE LES WILL CONTINUE THROUGH THE AFTN EVEN
THOUGH THE LOWER INVERSION HEIGHTS MAY END UP LEADING TO MAINLY
CLOUDS. OTHERWISE...TRANSITIONED TO MORE OF A -SHSN/FLURRIES IN THE
AFTN OVER THE W BEFORE DECREASING CLOUDS LATE IN THE AFTN DUE TO THE
WARMING H850 TEMPS AND DRIER AIR FINALLY ARRIVING WITH THE
APPROACHING SFC RIDGE.
HIGH PRESSURE RIDGE SLIDES OVER THE AREA TONIGHT...BRINGING AN END
TO THE LES OVER THE E AND THE LK CLOUDS OVER THE REST OF THE AREA.
WITH THE DECREASING CLOUDS AND WINDS...SHOULD BE A COLD NIGHT OVER
THE INTERIOR LOCATIONS. PWATS AROUND 35 PERCENT OF NORMAL WILL HELP
ENHANCE RADIATIONAL COOLING AND HAVE LOWS IN THE MID SINGLE DIGITS
ABOVE ZERO OVER THE INTERIOR W/CNTRL. WINDS WILL INCREASE SOME OVER
THE FAR W LATE IN THE NIGHT AHEAD OF THE NEXT WAVE...WHICH COULD
LEAD TO A RISE IN TEMPS LATE THERE.
NEXT SHORTWAVE AND ASSOCIATED LOW WILL BE MOVING THROUGH THE NRN
STREAM ON TUES...BUT WITH IT BEING LOCATED MUCH FARTHER N /OVER NRN
ONTARIO AND HUDSON BAY/ EXPECT IT TO HAVE LIMITED AFFECT ON THE
WEATHER OTHER THAN INCREASING THE WSW WINDS. SHOULD BE ANOTHER ABOVE
NORMAL TEMP DAY WITH A MOSTLY SUNNY SKY.
MODELS HAVE CONTINUED THE FASTER TREND WITH MERGING THE SRN STREAM
UPPER LOW CURRENTLY OVER THE SWRN CONUS WITH THE NRN STREAM ON WED
OVER THE LOWER GREAT LKS. WITH THE APPROACHING NRN STREAM WAVE STILL
OVER MANITOBA/SASK...AREA SHOULD BE BETWEEN SYSTEMS AND UNDER WEAK
HIGH PRESSURE TUES NIGHT AND WED MORNING. WILL GO WITH PARTLY CLOUDY
TO MOSTLY CLEAR SKIES FOR NOW...WITH CLOUDS JUST TO THE NW AND SE OF
THE CWA...BUT WILL BE CONTINGENT ON LOW CLOUDS HINTED AT BY THE NAM
NOT STICKING AROUND TOO LONG. THEN WITH SFC TROUGH TO THE
NW...ASSOCIATED WITH LOW OVER HUDSON BAY...NEARING THE CWA IN THE
AFTN AND MOVING THROUGH WED NIGHT...HAVE INCREASED CLOUDS FROM THE
AFTN ON. MOISTURE/FORCING IS WEAK WITH THE PASSAGE OF THE
TROUGH...SO WILL CONTINUE MENTION OF SLIGHTS OVER WRN LK SUPERIOR IN
THE AFTN AND SLIGHTS/LOW CHANCES ALONG THE FRONT WED NIGHT.
UPPER TROUGH THEN SWEEPS ACROSS THE AREA LATE WED NIGHT INTO
FRI...BRINGING A BETTER CHANCE FOR SNOW BEHIND THE FRONT. SOME
DIFFERENCES IN THE H850 TEMPS WITH THE 00Z GFS AND 12Z ECMWF...BUT
OVERALL IDEA IS AROUND -12C...WHICH WOULD CREATE LARGE ENOUGH
DELTA-T VALUES FOR LES. AS IS THE CASE TODAY...H800-650 SUBSIDENCE
AND DRY AIR WILL LIMIT THE INVERSION HEIGHTS TO 4KFT. SHOULD BE
DECENT LLVL MOISTURE TO WORK WITH BELOW THE INVERSION...SO AM
CONFIDENT ENOUGH TO GO WITH CHANCE POPS. WITH THE FORCING BELOW THE
DGZ /CLOUD TOPS ONLY REACH -15C ON THE COLDER GFS/ EXPECT SNOW
RATIOS TO BE IN THE LOW TEENS AND WILL LIKELY ONLY SEE A LIGHT
DUSTING FOR AREAS FAVORED BY A NNW WIND.
UPPER TROUGH STARTS TO SHIFT E ON FRI AS SFC HIGH BEGINS TO PUSH
OVER THE AREA. DRIER AIR ASSOCIATED WITH THE HIGH WILL LEAD TO
DIMINISHING LES POPS THURS NIGHT WEST AND DURING THE DAY FRI
EAST...AS WINDS BECOME ANTICYCLONIC. MAY SEE WEAK UPPER RIDGING ON
SAT...AHEAD OF THE NEXT NRN STREAM TROUGH TO AFFECT THE AREA SAT
NIGHT INTO SUN. ONCE AGAIN...FORCING/MOISTURE LIMITED ALONG THE
FRONT AND THE BEST POTENTIAL FOR PCPN WILL COME ON SUN WITH LES...AS
H850 TEMPS FALL TOWARDS -13C.
&&
.AVIATION /FOR THE 06Z TAF ISSUANCE/...
A TROUGH/COLD FRONT SAGGING INTO UPPER MICHIGAN BEHIND LOW PRES
MOVING EAST THROUGH NRN ONTARIO WILL PUSH WINDS TO A MORE NW
DIRECTION...AS WELL AS INCREASED LOW LEVEL MOISTURE AND PLENTY OF
COLD AIR. EXPECT MVFR CIGS BEHIND THE COLD FRONT...LOWEST AT CMX AND
IWD...GIVEN THE FAVORABLE NW UPSLOPE WINDS OFF LAKE SUPERIOR.
CONDITIONS SHOULD IMPROVE TO VFR BY LATE MORNING AS DRIER AIR MOVES
IN.
&&
.MARINE /FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE/...
IN THE WAKE OF A COLD FRONT MOVING SE ACROSS LAKE SUPERIOR...A
PERIOD OF GALE FORCE GUSTS SHOULD OCCUR OVER THE E HALF OF THE LAKE
EARLY THIS MORNING IN ADVANCE OF 5MB/3HR PRES RISES. SINCE CORE OF
PRES RISES WILL SHIFT E OF LAKE SUPERIOR BY MID MORNING...GALE
WARNING WILL MOST LIKELY BE CANCELLED BY NEXT SCHEDULED FCST
ISSUANCE. OTHERWISE...WINDS WILL DIMINISH W TO E TODAY/TONIGHT AS
HIGH PRES QUICKLY APPROACHES AND THEN PASSES ACROSS THE GREAT LAKES.
DEEP LOW PRES MOVING E TO HUDSON BAY EARLY TUE WILL LIKELY BRING
ANOTHER ROUND OF SW GALES TO PORTIONS OF LAKE SUPERIOR...MAINLY THE
W HALF. SW WIND DIRECTION WILL FAVOR THE AREA BTWN THE KEWEENAW AND
ISLE ROYALE FOR STRONGEST WINDS TUE (GUSTS TO AROUND 40KT). GALES
WILL END TUE NIGHT AS PRES GRADIENT WEAKENS. WINDS WILL BE BLO 25KT
WED THRU FRI.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
GALE WARNING UNTIL 1 PM EST THIS AFTERNOON FOR LSZ250-251-266-
267.
GALE WATCH FROM TUESDAY MORNING THROUGH LATE TUESDAY NIGHT FOR
LSZ162-263-264.
GALE WARNING UNTIL 7 AM EST THIS MORNING FOR LSZ264.
LAKE MICHIGAN...
NONE.
&&
$$
DISCUSSION...SRF
AVIATION...JLB
MARINE...ROLFSON
AREA FORECAST DISCUSSION
NWS DULUTH MN
402 AM CST MON DEC 19 2011
.SHORT TERM...TODAY THROUGH TUESDAY...
SURFACE COLD FRONT CONTINUES TO PUSH STEADILY SOUTHWARD THROUGH
WISCONSIN EARLY THIS MORNING IN WAKE OF CLIPPER SYSTEM THAT PASSED
TO OUR NORTH YDAY. THE AIRMASS BEHIND THE COLD FRONT IS NOT
TERRIBLY COLD BY MID DECEMBER STANDARDS FOR THIS PART OF THE WORLD
WITH TEMPS IN THE TEENS TO LOWER 20S..BUT IS ALSO CHARACTERIZED BY
A VERY EXPANSIVE STRATOCUMULUS DECK THAT COVERS ALMOST THE ENTIRE
DULUTH CWA AS OF 330 AM AND EXTENDS SEVERAL HUNDRED MILES TO OUR
NORTH. THE EVOLUTION AND EVENTUAL DISSIPATION OF THIS CLOUD DECK
IS KEY TO THE FORECAST FOR TODAY AND TONIGHT. MOST OF THE SHORT
RANGE MODEL GUIDANCE HAS BEEN INSISTENT FOR MANY MODEL RUNS THAT
THE CLOUDS WILL BREAK UP VERY RAPIDLY THIS MORNING WITH THE HRRR
AND RUC BEING THE OUTLIERS WITH A MUCH MORE SLOW BREAK UP
SOLUTION. GIVEN THE SATELLITE APPEARANCE AND MID DECEMBER
CLIMATOLOGY..WE ARE MUCH LESS OPTIMISTIC THAT CLOUDS WILL BE ABLE
TO BREAK UP AS RAPIDLY AS MUCH OF THE MODEL GUIDANCE SUGGESTS AND
WE HAVE TRENDED TOWARD THE HRRR/RUC SOLUTIONS WHICH CALL FOR
GENERALLY CLOUDY SKIES UNTIL THIS EVENING. NORTHWEST WINDS WILL
CONTINUE TO BE GUSTY THIS MORNING AS 5 MB/3 HR PRESSURE RISE
CENTER CONTINUES TO TRANSLATE ACROSS NRN LAKE SUPERIOR WITH TIGHT
GRADIENT. HOWEVER..WINDS SHUD SLACKEN CONSIDERABLY BY AFTERNOON
WITH LOSS OF ISALLOBARIC COMPONENT AND WEAKENING GRADIENT.
HIGH PRESSURE WILL THEN BUILD INTO THE REGION TONIGHT AND LEAVE
THE AREA LARGELY IN BETWEEN THE BIG SYSTEM COMING OUT ONTO THE
PLAINS TO OUR SOUTH AND THE STRONG WNW FLOW ALOFT ACROSS CANADA.
S/SW FLOW WILL RETURN ON TUESDAY AS RIDGE MOVES TO OUR SOUTH AND
NEXT LOW AMPLITUDE WAVE APPROACHES FROM THE NORTHWEST. THIS
SYSTEM..ON SCHEDULE FOR TUE/TUE NITE..APPEARS TO BE SIMILAR TO
THE ONE THAT JUST PASSED BY WITH A BRIEF SURGE OF WARM AIR
FOLLOWED BY ANOTHER PACIFIC TYPE COLD FRONT TUE NIGHT.
&&
.LONG TERM...TUESDAY NIGHT THROUGH SUNDAY...
THE PERIOD SHOULD BEGIN INCREASING CLOUD COVER AS A COLD FRONT IN
MANITOBA AND ONTARIO APPROACHES THE CANADIAN BORDER TUESDAY NIGHT.
THE COLD FRONT WILL LIKELY MOVE THROUGH THE NORTHLAND
WEDNESDAY...RESULTING IN CLOUDY CONDITIONS AND POSSIBLE LIGHT SNOW
ACROSS THE NORTHERN FA. BOTH THE GFS AND ECMWF BRING 850 HPA
TEMPERATURES OF -8 TO -12 CELSIUS OVER WESTERN LAKE SUPERIOR
WEDNESDAY NIGHT AND THURSDAY IN THE WAKE OF THE COLD FRONT.
CONSIDERING THE LAKE SURFACE TEMPERATURE IS AROUND 4 DEGREES
CELSIUS...THAT RESULTS IN SURFACE TO 850 HPA TEMPERATURE DIFFERENCES
AROUND 12 TO 16 DEGREES. THE NORTHERLY WINDS THAT DEVELOP WEDNESDAY
NIGHT AND THURSDAY COULD THEREFORE RESULT IN LAKE EFFECT SNOW ACROSS
THE PARTS OF THE SOUTH SHORE. THE MODELS BRING HIGH PRESSURE INTO
THE UPPER MIDWEST THURSDAY AND FRIDAY...RESULTING IN CLEARING SKIES.
A WARMING TREND LOOKS LIKELY FRIDAY INTO SATURDAY AS SOUTHERLY WINDS
INCREASE AHEAD OF AN APPROACHING COLD FRONT FROM THE WEST. SUNDAY
LOOKS COLDER AND CLOUDY IN THE WAKE OF THE COLD FRONT. THERE MAY BE
SOME LIGHT SNOW.
&&
.AVIATION...06Z TAF ISSUANCE...
CEILINGS ANYWHERE FROM 700FT TO 2500FT WERE ADVANCING SOUTH
THROUGH THE MOST OF NORTHERN MINNESOTA AS OF 0530Z...AND WILL
OVERTAKE NORTHERN WISCONSIN OVER THE NEXT FEW HOURS. WINDS HAD
SWITCHED OUT OF THE NORTHWEST OVER NORTHERN MINNESOTA...AND WILL
BE SWITCHING OVER THE NEXT FEW HOURS OVER NORTHERN WISCONSIN.
STRONG CAA WILL CONTINUE TONIGHT...AND MAY PRODUCE SOME
FLURRIES...WITH SOME SNOW SHOWERS LATE OVER SNOWBELT OF NORTHERN
WISCONSIN. ANY ACCUMULATION WILL BE LIGHT. DRYING IS EXPECTED
MONDAY MORNING...AND MODELS AND NUMERICAL GUIDANCE SUGGESTS MUCH
OF THE CLOUD WILL CLEAR DURING THE MORNING. CURRENT SATELLITE
SHOWS A SMALL BREAK IN FAR WESTERN MINNESOTA...WITH CLOUDS COVER
MUCH OF NORTHWEST ONTARIO/SOUTHEAST MANITOBA. WE WENT SCATTERED AT
MOST TAFS SITES AROUND 16Z.
&&
.POINT TEMPS/POPS...
DLH 23 8 25 16 / 0 0 0 0
INL 21 9 28 18 / 10 0 10 10
BRD 25 10 27 15 / 0 0 0 0
HYR 26 9 25 16 / 0 0 0 0
ASX 28 14 28 20 / 20 0 0 0
&&
.DLH WATCHES/WARNINGS/ADVISORIES...
MN...NONE.
WI...NONE.
LS...SMALL CRAFT ADVISORY UNTIL 3 PM CST THIS AFTERNOON FOR LSZ146-
147.
&&
$$
MILLER/GROCHOCINSKI
AREA FORECAST DISCUSSION
NWS GRAND FORKS ND
235 AM CST MON DEC 19 2011
.DISCUSSION...FORECAST CHALLENGE CONCERNS MAINLY TEMPERATURES.
MODELS IN GOOD AGREEMENT. FOR PERSISTENCE WILL FOLLOW GFS FOR
DETAILS.
COLD ADVECTION CONTINUES EARLY THIS MORNING LEVELING OFF TOWARDS
LATE MORNING. COOLING HAS BEEN OFFSET BY MIXING AND CLOUD COVER.
CLOUDS LIKELY TO HOLD MINIMUMS UP THIS MORNING BUT WHEN CLOUDS BREAK
UP WILL DETERMINE HOW MUCH RECOVERY TODAY. RUC HOLDING IN LAYERED RH
THROUGH 18Z WITH GFS DRYING COLUMN DURING THE AFTERNOON AS HIGH
PRESSURE BUILDS IN. WILL BE RAISING MAX TEMPERATURES TODAY BASED ON
ANTICIPATED WARMER START. WITH LACK OF SNOW COVER AND LEVELING OFF
OF COLD ADVECTION ANY CLOUD BREAKS THIS AFTERNOON WILL ALLOW FOR A
MINOR TEMPERATURE RECOVERY.
HIGH PRESSURE WILL SAG SOUTH AND EAST OVERNIGHT INTO TUESDAY. THIS
WILL EVENTUALLY SET UP RETURN FLOW AND MODEST WARM ADVECTION FOR
TUESDAY. SKIES SHOULD CLEAR OFF ALONG WITH DIMINISHING WIND TONIGHT.
AGAIN LACK OF SNOW COVER WILL AFFECT MINIMUM TEMPERATURES AND STAY
WARMER THAN GUIDANCE. TRENDS CONTINUE TUESDAY WILL MAINTAIN MAXIMUM
TEMPERATURES WELL ABOVE GUIDANCE WITH LACK OF ANY SNOW COVER AND
ANTICIPATED SOLAR.
WEAK SURFACE TROUGH WILL CROSS FA TUESDAY NIGHT HOWEVER MOISTURE
LOOKS LIMITED SO WILL DROP LOW END POPS.
MID LEVEL FLOW REMAINS SPLIT WITH UPPER LOW CURRENTLY ACROSS DESERT
SW TRACKING EAST WELL SOUTH OF FA ON WEDNESDAY. ANY NORTHERN STREAM
MID LEVEL SUPPORT LOOKS WEAK HOWEVER WITH BAROCLINIC ZONE DROPPING
THROUGH FA COULD SEE SOME PATCHY -SN OR FLURRIES. WITH SPOTTY NATURE
OF MODEL QPF WILL NOT MAKE ANY MODIFICATIONS TO CURRENT SLIGHT
CHANCE POPS.
.LONG TERM (THU-SUN)...
MODELS IN GOOD AGREEMENT WITH THE EXTENDED PATTERN... INDICATING
LITTLE CHANGE TO THE ONGOING OVERALL DRY PATTERN WITH WIDE
TEMPERATURE SWINGS AS SHORT WAVES TRAVERSE THE REGION. A SEASONABLY
COOL AIRMASS IN PLACE ON THURSDAY WILL LEAD TO NEAR NORMAL HIGHS AND
TRANSITION QUICKLY AS 500MB RIDGING BUILDS INTO THE NORTHERN PLAINS
WITH WAA OCCURS DURING THE DAY FRIDAY AND THE FIRST HALF OF
SATURDAY. THE ONLY PRECIP IN THE EXTENDED LOOKS TO BE FROM A COLD
FRONT SATURDAY NIGHT THAT MAY BRING A DUSTING OF SNOW TO THE AREA.
&&
.AVIATION...
SOME BINOVC SHOWING UP FROM VALLEY WEST BUT OVERALL EXPECT MVFR/VFR
CIGS TO PERSIST INTO EARLY AFTERNOON. VFR TO MVFR CIGS SPOTTY AND
VERY DIFFICULT TO PINPOINT WITH FORECAST WITH LOWEST CIGS EAST OF
VALLEY.
&&
.FGF WATCHES/WARNINGS/ADVISORIES...
ND...NONE.
MN...NONE.
&&
$$
VOELKER/JIMMY K
AREA FORECAST DISCUSSION...UPDATED
NWS FORT WORTH TX
1137 PM CST SUN DEC 18 2011
.AVIATION...
AN UPPER LEVEL LOW CURRENTLY OVER SOUTHEASTERN ARIZONA...WILL
MOVE EAST ACROSS THE SOUTHERN PLAINS IN THE NEXT 24 TO 36 HOURS.
INCREASING LOW LEVEL MOISTURE HAS BROUGHT MVFR CEILINGS MAINLY
WEST OF I-35 AS OF 05Z...AND THESE CEILINGS WILL SPREAD ACROSS
THE REST OF THE TAF SITES BETWEEN 06Z AND 09Z. MVFR CEILINGS
SHOULD THEN HOLD IN FOR MOST...IF NOT...ALL OF THE DAY MONDAY. AN
INITIAL BAND OF SHOWERS AND THUNDERSTORMS BETWEEN ABILENE AND
WICHITA FALLS AS OF 05Z...WILL MOVE OFF TO THE NORTHEAST AND NOT
AFFECT THE AREA AIRPORTS. CAN NOT RULE OUT A CHANCE OF
SHOWERS/THUNDERSTORMS MID TO LATE MORNING AT THE TAF SITES BUT
UNCERTAINTY IS TOO HIGH TO MENTION AT THIS TIME. A LINE OF
THUNDERSTORMS IS EXPECTED TO DEVELOP ACROSS WEST TEXAS BY MIDDAY
MONDAY AND MOVE EAST ACROSS NORTH TEXAS DURING THE AFTERNOON AND
EVENING HOURS. FOR NOW HAVE PLACED 6SM -TSRA FOR THE MOST LIKELY
PERIOD OF 22Z-02Z...THOUGH SOME EARLIER ACTIVITY MAY OCCUR AHEAD
OF THE MAIN LINE OF THUNDERSTORMS. WINDS SHOULD SHIFT TO
SOUTHWEST 02-04Z.
58
&&
.UPDATE...
IMPRESSIVE UPPER LEVEL STORM SYSTEM IS SHOWING GOOD WV SATELLITE
STRUCTURE AS IT CHURNS ALONG OVER SOUTHEASTERN AZ AND APPROACHES
TEXAS FROM THE WEST. ISOLATED CONVECTION CONTINUES NEAR THE COLD
CENTER OF THE LOW...AND HAS ALSO DEVELOPED JUST WEST OF THE
FORECAST AREA IN ZONE OF INCREASING ASCENT AND MOISTURE RETURN
AHEAD OF THE FEATURE. STILL EXPECT PRECIPITATION TO REMAIN
ISOLATED AND MOSTLY WEST OF THE INTERSTATE 35 CORRIDOR THROUGH
EARLY MONDAY MORNING. SHOWERS AND THUNDERSTORMS WILL THEN INCREASE
RAPIDLY LATE TOMORROW MORNING AND INTENSIFY DURING THE AFTERNOON
HOURS AS THE SYSTEM BARRELS INTO THE AREA WITH A NEGATIVELY TILTED
AXIS...IMPRESSIVE DYNAMICS...AND FAIRLY GOOD INSTABILITY FOR THIS
TIME OF YEAR.
FOR THIS UPDATE WILL ADD MENTION OF ISOLATED THUNDER WEST OF I
35/35W WHERE A FEW STRIKES MAY OCCUR BETWEEN MIDNIGHT AND 6 AM
FRIDAY. OTHERWISE FORECAST IS ON TRACK.
30
&&
.PREV DISCUSSION... /ISSUED 407 PM CST SUN DEC 18 2011/
12Z UPPER AIR ANALYSIS INDICATED THAT A CUT OFF LOW REMAINED IN
PLACE OVER FAR SOUTHERN CA WITH RIDGING OVER THE GULF OF MEXICO.
THIS LEFT SOUTHWEST FLOW ALOFT OVER THE SOUTHERN PLAINS OUT AHEAD
OF THE UPPER LOW. SOUTHWEST FLOW ALOFT HAD LED TO THE ADVECTION OF
STEEP LAPSE RATES INTO WEST TX THIS MORNING WITH A TEMPERATURE
DIFFERENCE IN THE H700 TO H500 LAYER OF 22 DEG C. A POOL OF 10 DEG
C DEW POINTS WAS OBSERVED AT THE H850 LEVEL OVER FAR SOUTH TX AND
THE EFFECTS OF LEE SIDE CYCLOGENESIS WERE BECOMING EVIDENT WITH
THE DEVELOPMENT OF A CYCLONIC CIRCULATION OVER FAR WEST TX. 21Z
SFC ANALYSIS INDICATED THAT A MOISTURE WAS RAPIDLY RETURNING TO
WESTERN AND CENTRAL TX WITH 45 DEG F DEW POINTS OBSERVED AS VAR
NORTH AS CHILDRESS.
TONIGHT THROUGH TUESDAY...AFTERNOON WATER VAPOR IMAGERY INDICATED
THAT THE CUT OFF LOW AS ALREADY BEGINNING TO MOVE EAST AND THE
CENTER OF CIRCULATION HAD JUST CROSSED OVER THE SOUTHERN AZ BORDER
AS OF 21Z. A PLUME OF PACIFIC MOISTURE HAS ALREADY BEEN ADVECTED
OVER MUCH OF THE SOUTHERN PLAINS...AND SOUTHWEST FLOW ALOFT
CONTINUES THIS TRANSPORT OF MID TO UPPER TROPOSPHERIC MOISTURE
INTO THE REGION. THE PROGRESSION OF SURFACE DEW POINTS WAS THE
MOST INTERESTING PIECE OF INFORMATION THAT COULD BE OBSERVED ABOUT
THE POTENTIAL THERMODYNAMIC ENVIRONMENT THIS AFTERNOON AHEAD OF
THIS UPPER LOW. BASED ON 12Z GUIDANCE...THE NAM WAS THE ONLY MODEL
TO SUFFICIENTLY HANDLE THE RAPID INFLUX OF LOW LEVEL MOISTURE INTO
TX. THE NAM HAD ROUGHLY AN ACCURATE REPRESENTATION OF 21Z DEW
POINTS ACROSS TX WITH THE GFS LAGGING BEHIND BY 6 HRS AND THE
ECMWF COMING IN A FEW DEG F TOO LOW FOR ITS 00Z FORECAST THIS
EVENING. EVEN THE 18Z INITIALIZATION OF THE RUC IS SLOW ON THIS
MOISTURE TRANSPORT WHICH POINTS TO A POTENTIALLY SIGNIFICANT
SOURCE OF ERROR WITH REGARDS TO HANDLING THE THERMODYNAMIC
ENVIRONMENT THAT WILL SET UP OVER NORTH TX TOMORROW.
DID NOT CHANGE MUCH WITH REGARDS TO THE TIMING OF EXPECTED
PRECIPITATION ACROSS NORTH TX WITH THIS FORECAST PACKAGE. THE
UPPER LEVEL SYSTEM AND ASSOCIATED FRONTAL BOUNDARIES ARE EXPECTED
TO MOVE THRU NORTH TX AT ROUGHLY THE SAME TIME AS THE PREVIOUS
FORECAST INDICATED. THE UPPER LOW IS EXPECTED TO MOVE INTO THE
SOUTHERN PLAINS TOMORROW EVENING AND THEN BECOME NEGATIVELY TILTED
AS IT MOVES NORTHEAST OVER NORTH CENTRAL TX AND OVER OK MONDAY
NIGHT. STRONG LARGE SCALE FORCING FOR ASCENT WILL SPREAD OVER
NORTH TX AHEAD OF THIS UPPER LOW...WITH MAXIMUM ASCENT SPREADING
OVER THE FORECAST AREA FROM 21Z MONDAY TO 06Z TUESDAY. THE
FORECAST STRENGTH OF THE UPPER LOW AS IT MOVES OVER THE SOUTHERN
PLAINS IS HIGH WITH H500 HEIGHTS REGISTERING AS A -2.5 STANDARD
DEVIATION ANOMALY PER HPCS ANALYSIS OF THE 12Z GFS. PRECIPITABLE
WATER VALUES CONTINUE TO BE FORECAST TO HOLD IN THE 99TH
PERCENTILE OVER NORTH TX FOR DECEMBER. THE 0 TO 6 KM BULK SHEAR
MAGNITUDE IS EXPECTED TO BE IN EXCESS OF 55 KTS DURING THE PERIOD
OF MAXIMUM FORCING FOR ASCENT WHICH SPEAKS TO THE STRENGTH OF THE
WIND FIELDS OUT AHEAD OF THIS SYSTEM. INSTABILITY CONTINUES TO BE
THE MOST DIFFICULT PARAMETER TO FORECAST...AND THE DEGREE OF
INSTABILITY WILL LARGELY DETERMINE OUR SEVERE WEATHER CHANCES AND
COVERAGE TOMORROW AFTERNOON.
BASED ON 21Z SURFACE OBS...THE NAM APPEARS TO HAVE THE BEST HANDLE
ON LOW LEVEL MOISTURE MOISTURE RETURN OUT AHEAD OF THIS SYSTEM.
MOISTURE TRANSPORT IS EXPECTED TO INCREASE IN INTENSITY TONIGHT
AND DURING THE DAY MONDAY AS THE UPPER LEVEL LOW MOVES OVER THE
SOUTHERN PLAINS. THE LOW LEVEL JET IS FORECAST TO INCREASE TO AT
LEAST 50 KTS OVER NORTH TX TOMORROW...WITH OUR LOCAL 4 KM WRF
INDICATING A POTENTIAL JET CORE OF 60 KTS AFTER 21Z. STRATUS IS
STILL EXPECTED TO BE IN PLACE OVER MOST OF THE OPEN WARM SECTOR
TOMORROW WHICH WILL BE A LIMITING FACTOR FOR LOW LEVEL
DESTABILIZATION. HOWEVER WITH MOISTURE TRANSPORT LIKELY
UNDERESTIMATED IN MOST OPERATIONAL GUIDANCE...THINK THAT SURFACE
BASED INSTABILITY IS LIKEWISE UNDERESTIMATED. 12Z MOS GUIDANCE IS
NOW CONSISTENT WITH MID 60S HIGHS FOR DFW TOMORROW. MOS GUIDANCE
ALSO INDICATES HIGHS IN THE UPPER 60S TO LOWER 70S FOR WACO
TOMORROW. THIS IS A FEW DEGREES WARMER THAN HIGHS WERE EXPECTED TO
CLIMB FROM YESTERDAYS FORECAST.
CONFIDENCE IN THESE HIGHER TEMPERATURES IS INCREASING DUE TO
SIGNIFICANT BREAKS IN CLOUD COVER OVER NORTH TX AND THE TX GULF
COAST. WARMER AFTERNOON TEMPERATURES TODAY WILL THEORETICALLY LEAD
TO WARMER OVERNIGHT LOWS ONCE CLOUD COVER BUILDS BACK IN TONIGHT.
THIS WOULD MEAN THAT LESS HEATING IS NECESSARY TO REACH HIGHER
TEMPERATURES TOMORROW AFTERNOON. THE 12 AND 18Z NAM RUNS BOTH
CONTINUE TO AGGRESSIVELY ADVERTISE FREE CONVECTION POTENTIAL
TOMORROW AFTERNOON AND EVENING. WITH THE NAM HAVING THE BEST
HANDLE ON LOW LEVEL MOISTURE AND HIGH TEMPERATURES LIKELY CLIMBING
A FEW DEGREES HIGHER TOMORROW THAN PREVIOUS EXPECTED...CONFIDENCE
IN THE NAMS THERMODYNAMIC SOLUTION HAS INCREASED SUBSTANTIALLY.
THE NAM ADVERTISES A CORRIDOR OF SURFACE BASED CAPE OF 1000 J/KG
EXTENDING FROM THE METROPLEX SOUTH...NEAR THE INTERSTATE 35
CORRIDOR BY 00Z TUE OR TOMORROW AT 6 PM.
AS PREVIOUS FORECAST MENTIONED...LOW LCL HEIGHTS INDICATE THAT A
SIGNIFICANT PORTION OF THE FREE CONVECTION POTENTIAL ENERGY /CAPE/
WILL LIE IN THE LOWEST 3 KMS. 0 TO 3 KM CAPE VALUES ARE FORECAST
TO BE IN EXCESS OF 200 J/KG WITHIN THIS SAME GENERAL CORRIDOR.
THESE VALUES ARE QUITE HIGH EVEN FOR A SPRING SEVERE WEATHER
EPISODE...AND HIGH LOW LEVEL CAPE VALUES SPEAK TO THE POTENTIAL
FOR LOW LEVEL STRETCHING AND TILTING OF HORIZONTAL VORTICITY INTO
THE VERTICAL. LOW LEVEL WIND PROFILES CONTINUE TO VEER WITH HEIGHT
AND CONTAIN SIGNIFICANT SPEED SHEAR DUE TO THE PRESENCE OF THE
STRONG LOW LEVEL JET. 0-1 KM HELICITY VALUES IN EXCESS OF 200
M2/S2 ARE PRESENT WITHIN THE CORRIDOR OF HIGH LOW LEVEL CAPE. THIS
COMBINATION OF PARAMETERS INDICATES THAT ANY UPDRAFT WILL HAVE A
STRONG LIKELIHOOD TO INGEST HORIZONTAL VORTICITY WHICH GREATLY
INCREASES THE SEVERE WEATHER THREAT TOMORROW AFTERNOON. THE
GENERAL STORM MODE IS STILL EXPECTED TO BE LINEAR WITH SIGNIFICANT
FORCING FOR ASCENT EXPECTED ALONG A PACIFIC TYPE COLD FRONT THAT
WILL MOVE TROUGH NORTH TX JUST AHEAD OF THE CORE OF THE UPPER LOW.
THIS NORTH/SOUTH ORIENTED FRONT IS ORIENTED NEARLY PARALLEL TO THE
0-6 KM BULK SHEAR VECTORS WHICH GENERALLY FAVORS SHARED COLD POOLS
LEADING TO A LINEAR STORM MODE.
EVEN WITH A LINEAR STORM MODE STRETCHING AND TILTING OF HORIZONTAL
VORTICITY INTO THE VERTICAL CAN LEAD TO THE DEVELOPMENT OF
MESOVORTICIES CAPABLE OF PRODUCING STRONG LOCALIZED WIND
DAMAGE...AND TO THE DEVELOPMENT OF BRIEF TORNADOES. ANY DISCRETE
STORMS OUT AHEAD OF LINE SEGMENT CONVECTION WILL LIKELY BE IN THE
FORM OF LOW-TOPPED AND VERY FAST MOVING SUPERCELLS. ANY LOW-TOPPED
SUPERCELL AWAY FROM THE MAIN LINE OF CONVECTION WILL BE CAPABLE OF
PRODUCING A TORNADO...ESPECIALLY SOUTH OF THE METROPLEX TOMORROW
AFTERNOON. THE MOST WIDESPREAD SEVERE WEATHER HAZARD IS THOUGHT
TO BE IN THE FORM OF STRAIGHT LINE WIND DAMAGE...AND THIS IS
MOSTLY DUE TO THE POTENTIAL FOR STRONG ENVIRONMENTAL WINDS TO BE
DRIVEN DOWN TO THE SURFACE. DEEP MOISTURE MEANS THAT THERE IS
LITTLE THETA-E DIFFERENCE WITH HEIGHT...AND THEREFORE LITTLE
POTENTIAL FOR ENHANCED DOWNDRAFT SPEEDS OR MICROBURSTS.
OVERALL CONFIDENCE IN AN ORGANIZED STORM MODE IS HIGH NOW FOR
TOMORROW AFTERNOON. DAMAGING STRAIGHT LINE WINDS WITH A HIGH
POTENTIAL FOR LOCALLY ENHANCED DAMAGE IS THE MOST PREVALENT SEVERE
WEATHER HAZARD. THERE IS AN ATTENDANT TORNADO THREAT TOMORROW
AFTERNOON...ESPECIALLY IF ANY DISCRETE STORMS ARE ABLE TO DEVELOP
OUT AHEAD OF THE SQUALL LINE/PACIFIC FRONT. 99TH PERCENTILE PWATS
ALWAYS RAISE THE POTENTIAL FOR LOCALIZED FLOODING ISSUES...HOWEVER
THE VERY FAST STORM MOTION IS EXPECTED TO MITIGATE SIGNIFICANT
FLOODING CONCERNS.
THE PACIFIC TYPE COLD FRONT IS EXPECTED TO MOVE EAST THRU MOST OF
NORTH TX BY MIDNIGHT /06Z TUE/ MONDAY NIGHT. THE ATTENDANT SQUALL
LINE WILL LIKELY BE JUST EXITING THE FORECAST AREA AT THIS TIME
SO HAVE LINGERED HIGH POPS OVER THE FAR EASTERN CWA AFTER
MIDNIGHT. BY TUESDAY MORNING THERE IS SOME LOW END POTENTIAL FOR
LIGHT RAIN ASSOCIATED WITH MOISTURE WRAPPED AROUND THE UPPER
LOW...ESPECIALLY AS SOME RESIDUAL FRONTOGENETIC FORCING BUILDS
INTO THE NORTHERN CWA AS THE CANADIAN AIRMASS RESPONSIBLE FOR THE
BLIZZARD PORTION OF THIS SYSTEM /OVER THE SOUTHERN HIGH PLAINS/
MOVES SOUTH INTO NORTH TX. NO WINTRY PRECIPITATION IS EXPECTED AT
THIS TIME AS THERE WILL BE VERY LITTLE MOISTURE LEFT TO WORK WITH
AND TEMPERATURES WILL GENERALLY REMAIN ABOVE FREEZING EARLY
TUESDAY MORNING BEHIND THE FRONT.
EXTENDED...NO SIGNIFICANT CHANGES MADE TO THE EXTENDED AT THIS
TIME. KEPT THE LOW END RAIN CHANCES OVER THE SOUTHEASTERN PORTION
OF THE CWA ON THURSDAY AS ANOTHER SHORTWAVE TROUGH MOVES OVER
NORTH TX. THE 12Z ECMWF WAS THE MOST AGGRESSIVE WITH PRECIPITATION
BECAUSE IT BRINGS THE WAVE OVER NORTH TX THE FURTHEST NORTH AND
STRONGER THAN THE GFS ADVERTISES. EITHER WAY LIMITED MOISTURE WILL
PREVENT SIGNIFICANT COVERAGE OF RAIN OVER NORTH TX ON THURSDAY.
MAINTAINED A DRY FORECAST FOR THE HOLIDAY WEEKEND AS RUN TO RUN
AND MODEL TO MODEL CONSISTENCY EVEN ON LARGE SCALE FLOW REMAINS
POOR AT THIS TIME. GENERAL CONSENSUS IS THAT TEMPERATURES WILL BE
BELOW NORMAL...SO FOR NOW A COOL AND DRY HOLIDAY WEEKEND IS
EXPECTED.
CAVANAUGH
&&
.PRELIMINARY POINT TEMPS/POPS...
DALLAS-FT. WORTH, TX 51 64 45 50 31 / 10 80 100 5 5
WACO, TX 52 67 44 53 28 / 10 70 100 5 5
PARIS, TX 44 63 47 54 30 / 10 50 100 10 10
DENTON, TX 52 61 43 46 27 / 10 90 100 10 5
MCKINNEY, TX 48 62 45 50 30 / 10 80 100 5 5
DALLAS, TX 51 64 46 50 31 / 10 80 100 5 5
TERRELL, TX 48 64 49 53 31 / 10 50 100 5 5
CORSICANA, TX 48 66 47 55 32 / 10 50 100 5 5
TEMPLE, TX 50 66 43 55 29 / 10 70 100 5 5
MINERAL WELLS, TX 53 64 39 46 25 / 20 100 80 10 5
&&
.FWD WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
58/30
AREA FORECAST DISCUSSION
NWS FORT WORTH TX
1037 PM CST SUN DEC 18 2011
.UPDATE...
IMPRESSIVE UPPER LEVEL STORM SYSTEM IS SHOWING GOOD WV SATELLITE
STRUCTURE AS IT CHURNS ALONG OVER SOUTHEASTERN AZ AND APPROACHES
TEXAS FROM THE WEST. ISOLATED CONVECTION CONTINUES NEAR THE COLD
CENTER OF THE LOW...AND HAS ALSO DEVELOPED JUST WEST OF THE
FORECAST AREA IN ZONE OF INCREASING ASCENT AND MOISTURE RETURN
AHEAD OF THE FEATURE. STILL EXPECT PRECIPITATION TO REMAIN
ISOLATED AND MOSTLY WEST OF THE INTERSTATE 35 CORRIDOR THROUGH
EARLY MONDAY MORNING. SHOWERS AND THUNDERSTORMS WILL THEN INCREASE
RAPIDLY LATE TOMORROW MORNING AND INTENSIFY DURING THE AFTERNOON
HOURS AS THE SYSTEM BARRELS INTO THE AREA WITH A NEGATIVELY TILTED
AXIS...IMPRESSIVE DYNAMICS...AND FAIRLY GOOD INSTABILITY FOR THIS
TIME OF YEAR.
FOR THIS UPDATE WILL ADD MENTION OF ISOLATED THUNDER WEST OF I
35/35W WHERE A FEW STRIKES MAY OCCUR BETWEEN MIDNIGHT AND 6 AM
FRIDAY. OTHERWISE FORECAST IS ON TRACK.
30
&&
.AVIATION...
CONCERNS...MVFR CEILINGS DEVELOPING 09-12Z. POSSIBLE
THUNDERSTORMS MONDAY AFTERNOON/EVENING.
AN UPPER LEVEL LOW CURRENTLY OVER SOUTHWESTERN ARIZONA...WILL
MOVE EAST ACROSS THE SOUTHERN PLAINS IN THE NEXT 24 TO 36 HOURS.
INCREASING SOUTHERLY LOW LEVEL FLOW WILL BRING SOME MVFR CEILINGS
NORTHWARD INTO WACO AROUND 09Z...AND INTO THE METROPLEX AROUND
12Z. MVFR CEILINGS SHOULD THEN HOLD IN FOR MOST...IF NOT...ALL OF
THE DAY. A LINE OF THUNDERSTORMS IS EXPECTED TO DEVELOP ACROSS
WEST TEXAS BY MIDDAY MONDAY AND MOVE EAST ACROSS NORTH TEXAS
DURING THE AFTERNOON AND EVENING HOURS. FOR NOW HAVE PLACED 6SM
-TSRA STARTING AT 21Z AT ALL OF THE TAF SITES...THOUGH SOME
EARLIER ACTIVITY MAY OCCUR AHEAD OF THE MAIN LINE OF
THUNDERSTORMS. WINDS SHOULD SHIFT TO SOUTHWEST AFTER 03Z.
58
&&
.PREV DISCUSSION... /ISSUED 407 PM CST SUN DEC 18 2011/
12Z UPPER AIR ANALYSIS INDICATED THAT A CUT OFF LOW REMAINED IN
PLACE OVER FAR SOUTHERN CA WITH RIDGING OVER THE GULF OF MEXICO.
THIS LEFT SOUTHWEST FLOW ALOFT OVER THE SOUTHERN PLAINS OUT AHEAD
OF THE UPPER LOW. SOUTHWEST FLOW ALOFT HAD LED TO THE ADVECTION OF
STEEP LAPSE RATES INTO WEST TX THIS MORNING WITH A TEMPERATURE
DIFFERENCE IN THE H700 TO H500 LAYER OF 22 DEG C. A POOL OF 10 DEG
C DEW POINTS WAS OBSERVED AT THE H850 LEVEL OVER FAR SOUTH TX AND
THE EFFECTS OF LEE SIDE CYCLOGENESIS WERE BECOMING EVIDENT WITH
THE DEVELOPMENT OF A CYCLONIC CIRCULATION OVER FAR WEST TX. 21Z
SFC ANALYSIS INDICATED THAT A MOISTURE WAS RAPIDLY RETURNING TO
WESTERN AND CENTRAL TX WITH 45 DEG F DEW POINTS OBSERVED AS VAR
NORTH AS CHILDRESS.
TONIGHT THROUGH TUESDAY...AFTERNOON WATER VAPOR IMAGERY INDICATED
THAT THE CUT OFF LOW AS ALREADY BEGINNING TO MOVE EAST AND THE
CENTER OF CIRCULATION HAD JUST CROSSED OVER THE SOUTHERN AZ BORDER
AS OF 21Z. A PLUME OF PACIFIC MOISTURE HAS ALREADY BEEN ADVECTED
OVER MUCH OF THE SOUTHERN PLAINS...AND SOUTHWEST FLOW ALOFT
CONTINUES THIS TRANSPORT OF MID TO UPPER TROPOSPHERIC MOISTURE
INTO THE REGION. THE PROGRESSION OF SURFACE DEW POINTS WAS THE
MOST INTERESTING PIECE OF INFORMATION THAT COULD BE OBSERVED ABOUT
THE POTENTIAL THERMODYNAMIC ENVIRONMENT THIS AFTERNOON AHEAD OF
THIS UPPER LOW. BASED ON 12Z GUIDANCE...THE NAM WAS THE ONLY MODEL
TO SUFFICIENTLY HANDLE THE RAPID INFLUX OF LOW LEVEL MOISTURE INTO
TX. THE NAM HAD ROUGHLY AN ACCURATE REPRESENTATION OF 21Z DEW
POINTS ACROSS TX WITH THE GFS LAGGING BEHIND BY 6 HRS AND THE
ECMWF COMING IN A FEW DEG F TOO LOW FOR ITS 00Z FORECAST THIS
EVENING. EVEN THE 18Z INITIALIZATION OF THE RUC IS SLOW ON THIS
MOISTURE TRANSPORT WHICH POINTS TO A POTENTIALLY SIGNIFICANT
SOURCE OF ERROR WITH REGARDS TO HANDLING THE THERMODYNAMIC
ENVIRONMENT THAT WILL SET UP OVER NORTH TX TOMORROW.
DID NOT CHANGE MUCH WITH REGARDS TO THE TIMING OF EXPECTED
PRECIPITATION ACROSS NORTH TX WITH THIS FORECAST PACKAGE. THE
UPPER LEVEL SYSTEM AND ASSOCIATED FRONTAL BOUNDARIES ARE EXPECTED
TO MOVE THRU NORTH TX AT ROUGHLY THE SAME TIME AS THE PREVIOUS
FORECAST INDICATED. THE UPPER LOW IS EXPECTED TO MOVE INTO THE
SOUTHERN PLAINS TOMORROW EVENING AND THEN BECOME NEGATIVELY TILTED
AS IT MOVES NORTHEAST OVER NORTH CENTRAL TX AND OVER OK MONDAY
NIGHT. STRONG LARGE SCALE FORCING FOR ASCENT WILL SPREAD OVER
NORTH TX AHEAD OF THIS UPPER LOW...WITH MAXIMUM ASCENT SPREADING
OVER THE FORECAST AREA FROM 21Z MONDAY TO 06Z TUESDAY. THE
FORECAST STRENGTH OF THE UPPER LOW AS IT MOVES OVER THE SOUTHERN
PLAINS IS HIGH WITH H500 HEIGHTS REGISTERING AS A -2.5 STANDARD
DEVIATION ANOMALY PER HPCS ANALYSIS OF THE 12Z GFS. PRECIPITABLE
WATER VALUES CONTINUE TO BE FORECAST TO HOLD IN THE 99TH
PERCENTILE OVER NORTH TX FOR DECEMBER. THE 0 TO 6 KM BULK SHEAR
MAGNITUDE IS EXPECTED TO BE IN EXCESS OF 55 KTS DURING THE PERIOD
OF MAXIMUM FORCING FOR ASCENT WHICH SPEAKS TO THE STRENGTH OF THE
WIND FIELDS OUT AHEAD OF THIS SYSTEM. INSTABILITY CONTINUES TO BE
THE MOST DIFFICULT PARAMETER TO FORECAST...AND THE DEGREE OF
INSTABILITY WILL LARGELY DETERMINE OUR SEVERE WEATHER CHANCES AND
COVERAGE TOMORROW AFTERNOON.
BASED ON 21Z SURFACE OBS...THE NAM APPEARS TO HAVE THE BEST HANDLE
ON LOW LEVEL MOISTURE MOISTURE RETURN OUT AHEAD OF THIS SYSTEM.
MOISTURE TRANSPORT IS EXPECTED TO INCREASE IN INTENSITY TONIGHT
AND DURING THE DAY MONDAY AS THE UPPER LEVEL LOW MOVES OVER THE
SOUTHERN PLAINS. THE LOW LEVEL JET IS FORECAST TO INCREASE TO AT
LEAST 50 KTS OVER NORTH TX TOMORROW...WITH OUR LOCAL 4 KM WRF
INDICATING A POTENTIAL JET CORE OF 60 KTS AFTER 21Z. STRATUS IS
STILL EXPECTED TO BE IN PLACE OVER MOST OF THE OPEN WARM SECTOR
TOMORROW WHICH WILL BE A LIMITING FACTOR FOR LOW LEVEL
DESTABILIZATION. HOWEVER WITH MOISTURE TRANSPORT LIKELY
UNDERESTIMATED IN MOST OPERATIONAL GUIDANCE...THINK THAT SURFACE
BASED INSTABILITY IS LIKEWISE UNDERESTIMATED. 12Z MOS GUIDANCE IS
NOW CONSISTENT WITH MID 60S HIGHS FOR DFW TOMORROW. MOS GUIDANCE
ALSO INDICATES HIGHS IN THE UPPER 60S TO LOWER 70S FOR WACO
TOMORROW. THIS IS A FEW DEGREES WARMER THAN HIGHS WERE EXPECTED TO
CLIMB FROM YESTERDAYS FORECAST.
CONFIDENCE IN THESE HIGHER TEMPERATURES IS INCREASING DUE TO
SIGNIFICANT BREAKS IN CLOUD COVER OVER NORTH TX AND THE TX GULF
COAST. WARMER AFTERNOON TEMPERATURES TODAY WILL THEORETICALLY LEAD
TO WARMER OVERNIGHT LOWS ONCE CLOUD COVER BUILDS BACK IN TONIGHT.
THIS WOULD MEAN THAT LESS HEATING IS NECESSARY TO REACH HIGHER
TEMPERATURES TOMORROW AFTERNOON. THE 12 AND 18Z NAM RUNS BOTH
CONTINUE TO AGGRESSIVELY ADVERTISE FREE CONVECTION POTENTIAL
TOMORROW AFTERNOON AND EVENING. WITH THE NAM HAVING THE BEST
HANDLE ON LOW LEVEL MOISTURE AND HIGH TEMPERATURES LIKELY CLIMBING
A FEW DEGREES HIGHER TOMORROW THAN PREVIOUS EXPECTED...CONFIDENCE
IN THE NAMS THERMODYNAMIC SOLUTION HAS INCREASED SUBSTANTIALLY.
THE NAM ADVERTISES A CORRIDOR OF SURFACE BASED CAPE OF 1000 J/KG
EXTENDING FROM THE METROPLEX SOUTH...NEAR THE INTERSTATE 35
CORRIDOR BY 00Z TUE OR TOMORROW AT 6 PM.
AS PREVIOUS FORECAST MENTIONED...LOW LCL HEIGHTS INDICATE THAT A
SIGNIFICANT PORTION OF THE FREE CONVECTION POTENTIAL ENERGY /CAPE/
WILL LIE IN THE LOWEST 3 KMS. 0 TO 3 KM CAPE VALUES ARE FORECAST
TO BE IN EXCESS OF 200 J/KG WITHIN THIS SAME GENERAL CORRIDOR.
THESE VALUES ARE QUITE HIGH EVEN FOR A SPRING SEVERE WEATHER
EPISODE...AND HIGH LOW LEVEL CAPE VALUES SPEAK TO THE POTENTIAL
FOR LOW LEVEL STRETCHING AND TILTING OF HORIZONTAL VORTICITY INTO
THE VERTICAL. LOW LEVEL WIND PROFILES CONTINUE TO VEER WITH HEIGHT
AND CONTAIN SIGNIFICANT SPEED SHEAR DUE TO THE PRESENCE OF THE
STRONG LOW LEVEL JET. 0-1 KM HELICITY VALUES IN EXCESS OF 200
M2/S2 ARE PRESENT WITHIN THE CORRIDOR OF HIGH LOW LEVEL CAPE. THIS
COMBINATION OF PARAMETERS INDICATES THAT ANY UPDRAFT WILL HAVE A
STRONG LIKELIHOOD TO INGEST HORIZONTAL VORTICITY WHICH GREATLY
INCREASES THE SEVERE WEATHER THREAT TOMORROW AFTERNOON. THE
GENERAL STORM MODE IS STILL EXPECTED TO BE LINEAR WITH SIGNIFICANT
FORCING FOR ASCENT EXPECTED ALONG A PACIFIC TYPE COLD FRONT THAT
WILL MOVE TROUGH NORTH TX JUST AHEAD OF THE CORE OF THE UPPER LOW.
THIS NORTH/SOUTH ORIENTED FRONT IS ORIENTED NEARLY PARALLEL TO THE
0-6 KM BULK SHEAR VECTORS WHICH GENERALLY FAVORS SHARED COLD POOLS
LEADING TO A LINEAR STORM MODE.
EVEN WITH A LINEAR STORM MODE STRETCHING AND TILTING OF HORIZONTAL
VORTICITY INTO THE VERTICAL CAN LEAD TO THE DEVELOPMENT OF
MESOVORTICIES CAPABLE OF PRODUCING STRONG LOCALIZED WIND
DAMAGE...AND TO THE DEVELOPMENT OF BRIEF TORNADOES. ANY DISCRETE
STORMS OUT AHEAD OF LINE SEGMENT CONVECTION WILL LIKELY BE IN THE
FORM OF LOW-TOPPED AND VERY FAST MOVING SUPERCELLS. ANY LOW-TOPPED
SUPERCELL AWAY FROM THE MAIN LINE OF CONVECTION WILL BE CAPABLE OF
PRODUCING A TORNADO...ESPECIALLY SOUTH OF THE METROPLEX TOMORROW
AFTERNOON. THE MOST WIDESPREAD SEVERE WEATHER HAZARD IS THOUGHT
TO BE IN THE FORM OF STRAIGHT LINE WIND DAMAGE...AND THIS IS
MOSTLY DUE TO THE POTENTIAL FOR STRONG ENVIRONMENTAL WINDS TO BE
DRIVEN DOWN TO THE SURFACE. DEEP MOISTURE MEANS THAT THERE IS
LITTLE THETA-E DIFFERENCE WITH HEIGHT...AND THEREFORE LITTLE
POTENTIAL FOR ENHANCED DOWNDRAFT SPEEDS OR MICROBURSTS.
OVERALL CONFIDENCE IN AN ORGANIZED STORM MODE IS HIGH NOW FOR
TOMORROW AFTERNOON. DAMAGING STRAIGHT LINE WINDS WITH A HIGH
POTENTIAL FOR LOCALLY ENHANCED DAMAGE IS THE MOST PREVALENT SEVERE
WEATHER HAZARD. THERE IS AN ATTENDANT TORNADO THREAT TOMORROW
AFTERNOON...ESPECIALLY IF ANY DISCRETE STORMS ARE ABLE TO DEVELOP
OUT AHEAD OF THE SQUALL LINE/PACIFIC FRONT. 99TH PERCENTILE PWATS
ALWAYS RAISE THE POTENTIAL FOR LOCALIZED FLOODING ISSUES...HOWEVER
THE VERY FAST STORM MOTION IS EXPECTED TO MITIGATE SIGNIFICANT
FLOODING CONCERNS.
THE PACIFIC TYPE COLD FRONT IS EXPECTED TO MOVE EAST THRU MOST OF
NORTH TX BY MIDNIGHT /06Z TUE/ MONDAY NIGHT. THE ATTENDANT SQUALL
LINE WILL LIKELY BE JUST EXITING THE FORECAST AREA AT THIS TIME
SO HAVE LINGERED HIGH POPS OVER THE FAR EASTERN CWA AFTER
MIDNIGHT. BY TUESDAY MORNING THERE IS SOME LOW END POTENTIAL FOR
LIGHT RAIN ASSOCIATED WITH MOISTURE WRAPPED AROUND THE UPPER
LOW...ESPECIALLY AS SOME RESIDUAL FRONTOGENETIC FORCING BUILDS
INTO THE NORTHERN CWA AS THE CANADIAN AIRMASS RESPONSIBLE FOR THE
BLIZZARD PORTION OF THIS SYSTEM /OVER THE SOUTHERN HIGH PLAINS/
MOVES SOUTH INTO NORTH TX. NO WINTRY PRECIPITATION IS EXPECTED AT
THIS TIME AS THERE WILL BE VERY LITTLE MOISTURE LEFT TO WORK WITH
AND TEMPERATURES WILL GENERALLY REMAIN ABOVE FREEZING EARLY
TUESDAY MORNING BEHIND THE FRONT.
EXTENDED...NO SIGNIFICANT CHANGES MADE TO THE EXTENDED AT THIS
TIME. KEPT THE LOW END RAIN CHANCES OVER THE SOUTHEASTERN PORTION
OF THE CWA ON THURSDAY AS ANOTHER SHORTWAVE TROUGH MOVES OVER
NORTH TX. THE 12Z ECMWF WAS THE MOST AGGRESSIVE WITH PRECIPITATION
BECAUSE IT BRINGS THE WAVE OVER NORTH TX THE FURTHEST NORTH AND
STRONGER THAN THE GFS ADVERTISES. EITHER WAY LIMITED MOISTURE WILL
PREVENT SIGNIFICANT COVERAGE OF RAIN OVER NORTH TX ON THURSDAY.
MAINTAINED A DRY FORECAST FOR THE HOLIDAY WEEKEND AS RUN TO RUN
AND MODEL TO MODEL CONSISTENCY EVEN ON LARGE SCALE FLOW REMAINS
POOR AT THIS TIME. GENERAL CONSENSUS IS THAT TEMPERATURES WILL BE
BELOW NORMAL...SO FOR NOW A COOL AND DRY HOLIDAY WEEKEND IS
EXPECTED.
CAVANAUGH
&&
.PRELIMINARY POINT TEMPS/POPS...
DALLAS-FT. WORTH, TX 51 64 45 50 31 / 10 80 100 5 5
WACO, TX 52 67 44 53 28 / 10 70 100 5 5
PARIS, TX 44 63 47 54 30 / 10 50 100 10 10
DENTON, TX 52 61 43 46 27 / 10 90 100 10 5
MCKINNEY, TX 48 62 45 50 30 / 10 80 100 5 5
DALLAS, TX 51 64 46 50 31 / 10 80 100 5 5
TERRELL, TX 48 64 49 53 31 / 10 50 100 5 5
CORSICANA, TX 48 66 47 55 32 / 10 50 100 5 5
TEMPLE, TX 50 66 43 55 29 / 10 70 100 5 5
MINERAL WELLS, TX 53 64 39 46 25 / 20 100 80 10 5
&&
.FWD WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
58/30
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
337 AM CST MON DEC 19 2011
.SHORT TERM...TODAY THROUGH WEDNESDAY
337 AM CST MON DEC 19 2011
MAIN FORECAST CONCERNS REMAIN ON STORM SYSTEM MOVING THROUGH THE
REGION TUESDAY AFTERNOON THROUGH EARLY WEDNESDAY...WITH THE
POTENTIAL FOR LIGHT FREEZING RAIN/SNOW.
CURRENT SURFACE OBSERVATIONS SHOWED A COLD FRONT EXTENDING FROM
EASTERN LAKE SUPERIOR...SOUTHWEST INTO NORTHEAST NEBRASKA...MOVING
SOUTHEAST TOWARD THE FORECAST AREA.
THE COLD FRONT WILL MOVE ACROSS THE AREA EARLY THIS MORNING WITH
STRATUS MOVING IN FROM NORTHWEST TO SOUTHEAST. LOOK FOR TEMPERATURES
TO FALL THROUGH THE DAY IN THE WAKE OF THE COLD FRONT...FROM THE MID
30S THIS MORNING TO THE MID TO UPPER 20S BY LATE THIS AFTERNOON. THE
NAM IS SHOWING SOME FRONTOGENESIS IN THE 850 THROUGH 700 MB LEVELS IN
THE 12 TO 15Z TIMEFRAME THIS MORNING. HOWEVER...THESE LEVEL ARE VERY
DRY WITH RH VALUES AROUND 50 PERCENT AT 12Z...FALLING TO AROUND 13
PERCENT BY 18Z. FORECAST SOUNDINGS ARE SHOWING THE CLOUD LAYER FROM
950-900 MB...WITH WEAK OMEGA THROUGH THIS LAYER. WILL HAVE TO WATCH
FOR FREEZING DRIZZLE POTENTIAL THIS MORNING. HAVE NOT SEEN ANY
VISIBILITY RESTRICTIONS OR LIGHT PRECIP REPORTS UPSTREAM THIS
MORNING AND THINKING THAT LIFT WILL BE TOO WEAK TO PRODUCE DRIZZLE.
NORTHWEST WINDS WILL INCREASE BEHIND THE FRONT TODAY. ACROSS THE
OPEN AREAS OF SOUTHEAST MINNESOTA AND NORTHEAST IOWA...LOOK FOR
WINDS TO INCREASE INTO THE 15 TO 25 MPH RANGE TODAY WITH GUSTS TO
AROUND 30 MPH POSSIBLE. RIDGE TOPS ACROSS WESTERN WISCONSIN MAY ALSO
SEE A FEW GUSTS IN THE 25 TO 30 MPH RANGE...OTHERWISE PLAN ON
NORTHWEST WINDS AT 10 TO 15 MPH ACROSS WESTERN WISCONSIN. WIND
CHILLS ARE EXPECTED TO FALL INTO THE TEENS THIS AFTERNOON. THE
STRATUS WILL LINGER ACROSS THE FORECAST AREA THROUGH EARLY EVENING
BEFORE SURFACE HIGH PRESSURE MOVES IN. PLAN ON GRADUALLY
DECREASING CLOUDS TONIGHT WITH LOWS FALLING INTO THE TEENS TO
LOWER 20S.
19.00 MODELS ARE IN AGREEMENT SHOWING A LOW PRESSURE SYSTEM MOVING
FROM SOUTHERN NEW MEXICO/TEXAS PAN HANDLE...NORTHEAST INTO THE
CENTRAL PLAINS. THE COLD FRONT THAT MOVES THROUGH THE REGION
TODAY...WILL PUSH SOUTH TONIGHT AND BECOME STATIONARY EXTENDING
FROM NORTHERN MISSOURI...EAST INTO THE OHIO RIVER VALLEY REGION.
THE FRONT WILL ACT AS A BAROCLINIC ZONE FOR THE LOW MOVING ACROSS
THE CENTRAL PLAINS. THE FRONT WILL LIFT NORTHWARD AS A WARM FRONT
LATE TONIGHT INTO TUESDAY AS THE LOW MOVES FROM
NEBRASKA...NORTHEAST INTO NORTHERN MISSOURI/SOUTHERN IOWA. THE
WARM FRONT IS EXPECTED TO MOVE INTO NORTHEAST IOWA/SOUTHERN
WISCONSIN TUESDAY AFTERNOON WITH A LIGHT RAIN/SNOW MIX SPREAD INTO
NORTHEAST IOWA AND FAR SOUTHWEST WISCONSIN. THE STRONGEST
ISENTROPIC LIFT ON THE 280 THROUGH 290 K SURFACES WILL BE FOCUSED
MAINLY ALONG AND SOUTH OF A WEST UNION TO BOSCOBEL WISCONSIN LINE
ON TUESDAY INTO TUESDAY NIGHT...SO THESE AREAS WILL HAVE THE BEST
CHANCE OF SEEING PRECIPITATION. FORECAST SOUNDINGS ARE SHOWING ICE
BEING LOST ALOFT LATE TUESDAY AFTERNOON INTO TUESDAY
EVENING...WITH RAIN/SNOW SWITCHING OVER TO LIGHT FREEZING RAIN AS
SURFACE TEMPERATURES COOL BELOW FREEZING. TWO WAVES OF POTENTIAL
VORTICITY ADVECTION OF 14 PVU/S LOOK TO MOVE ACROSS NORTHEAST IOWA
AND FAR SOUTHWEST WISCONSIN TUESDAY AFTERNOON AND AGAIN LATE
TUESDAY NIGHT. THE PRECIPITATION SHOULD REMAIN SOUTH OF INTERSTATE
90 THROUGH TUESDAY NIGHT. THERE IS THE POTENTIAL FOR A BRIEF
PERIOD OF SLEET ACROSS PORTIONS OF NORTHEAST IOWA AND FAR
SOUTHWEST WISCONSIN WHERE 19.00 FORECAST SOUNDINGS SHOW A WARM
LAYER PUSHING INTO THE AREA IN THE 09Z TO 12Z TIMEFRAME WITH MAX
TEMPERATURES ALOFT AROUND 3 DEGREES C. THE 19.06 NAM FORECAST
SOUNDINGS HAVE SHIFTED THE WARM LAYER SOUTH OF THIS AREA...SO ITS
LOOKING LIKE FREEZING RAIN WILL BE THE PRIMARY CONCERN THROUGH
TUESDAY NIGHT INTO EARLY WEDNESDAY MORNING. THE LOW IS EXPECTED TO
LIFT INTO SOUTHERN LOWER MICHIGAN BY LATE WEDNESDAY MORNING. LIGHT
RAIN/SNOW MAY LINGER ACROSS FAR SOUTHWEST WISCONSIN INTO THE LATE
MORNING HOURS. CLOUDS WILL BE ON THE DECREASE WEDNESDAY AFTERNOON
AS THE SYSTEM EXITS THE REGION. LOOK FOR HIGH TEMPERATURES TO
RANGE FROM THE LOWER 30S ACROSS NORTH CENTRAL WISCONSIN TO THE MID
30S ACROSS NORTHEAST IOWA.
.LONG TERM...THURSDAY THROUGH SUNDAY
337 AM CST MON DEC 19 2011
19.00 MODELS ARE GENERATING SOME LIGHT SNOW ACROSS NORTHWEST
SECTIONS OF THE FORECAST AREA ON WEDNESDAY NIGHT AS A WEAK FRONTAL
BOUNDARY MOVES THROUGH. THE NAM AND ECMWF ALONG WITH FORECAST
SOUNDINGS SUPPORT SATURATION AND WEAK LIFT ACROSS SOUTHEAST
MINNESOTA THROUGH NORTH CENTRAL WISCONSIN. HAVE ADDED A SLIGHT
CHANCE OF PRECIPITATION TO THESE AREAS. WILL HAVE TO KEEP A CLOSE
WATCH ON THE NEXT FEW MODEL RUNS...WITH THE POTENTIAL TO EXPAND
PRECIPITATION CHANCES TO THE SOUTHEAST ON THURSDAY. THE NEXT
SYSTEM IS EXPECTED TO APPROACH THE REGION LATE FRIDAY INTO
SATURDAY...THE MODELS ARE SHOWING DIFFERING SOLUTIONS. THE GFS
BRINGS AN UPPER LOW FROM THE CENTRAL ROCKIES THURSDAY NIGHT...INTO
NORTHERN MISSOURI AND NORTHERN ILLINOIS FRIDAY NIGHT INTO EARLY
SATURDAY. THE ECMWF TAKES THE TROUGH ACROSS THE SOUTHERN PLAINS
AND INTO THE APPALACHIANS. WILL HAVE TO CLOSELY MONITOR THE NEXT
FEW MODEL RUNS...THIS WILL BE OUR LAST REAL SHOT OF SEEING SNOW
FOR THE WEEKEND. FOR FRIDAY THROUGH SUNDAY...PLAN ON HIGHS IN THE
MID 20S TO LOWER 30S...WITH LOWS IN THE TEENS TO AROUND 20. AN
UPPER TROUGH IS EXPECTED TO MOVE ACROSS NORTHERN WISCONSIN ON
SUNDAY BRINGING A SLIGHT CHANCE OF SNOW TO LOCATIONS ACROSS NORTH
CENTRAL WISCONSIN.
&&
.AVIATION...THROUGH 06Z TUESDAY
1123 PM CST SUN DEC 18 2011
THE MAIN FOCUS CONTINUES TO BE ON THE COLD FRONT PASSAGE TIMING
AND WHEN THE LOW STRATUS DECK GETS INTO THE TAF REGION.
CURRENTLY...THIS COLD FRONT EXTENDS FROM JUST SOUTH OF LAKE
SUPERIOR DOWN TO SIOUX FALLS SOUTH DAKOTA. THIS STRATUS DECK IS
LAGGING BEHIND THE FRONTAL PASSAGE AND IS MAINLY MVFR BETWEEN 1KFT
TO 2KFT THOUGH A FEW OBS HAVE BEEN REPORTING 800FT CEILINGS. BASED
ON THESE TRENDS AND 19.03Z RUC SOUNDINGS FROM LSE/RST...HAVE
BACKED OUT OF THE IFR CEILING FORECAST AND BROUGHT THEM UP TO LOW
END MVFR TOWARD 10/11Z. WITH A LITTLE DEEPER MIXING AS THE DAY
PROGRESSES...WOULD EXPECT THESE CEILINGS TO GRADUALLY CLIMB THOUGH
STAY MVFR. WHEN/IF SKIES CLEAR OUT IS THE NEXT QUESTIONS WITH MUCH
OF THE FORECAST GUIDANCE SUGGESTING THAT THE CLOUDS WILL CLEAR BY
MID AFTERNOON. THIS MAY BE QUITE OPTIMISTIC THOUGH WITH A SHALLOW
INVERSION HOLDING ON INTO TOMORROW NIGHT. THUS...HAVE KEPT CIGS
AROUND THROUGH THE REST OF THE FORECAST PERIOD BUT ENDED THE
HIGHER GUSTS BY DUSK.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
337 AM CST MON DEC 19 2011
WI...NONE.
MN...NONE.
IA...NONE.
&&
$$
SHORT TERM...WETENKAMP
LONG TERM....WETENKAMP
AVIATION.....HALBACH
AREA FORECAST DISCUSSION
NWS MILWAUKEE/SULLIVAN WI
327 AM CST MON DEC 19 2011
.TODAY AND TONIGHT...FORECAST CONFIDENCE MEDIUM TO HIGH.
MID/UPPER JET MAX ACROSS THE NORTHERN GREAT LAKES TAKES THE MID
LEVEL SHORTWAVE AND ASSOCIATED LOW NORTHEAST OF LAKE
SUPERIOR...OFF TO THE EAST THIS MORNING...WITH A WEAK MID LEVEL
TROUGH AXIS PUSHING DOWN ACROSS SOUTHERN WISCONSIN TONIGHT.
850MB THERMAL RIDGE WILL EXTEND ACROSS SOUTHERN WISCONSIN EARLY
THIS MORNING. RUC SOUNDINGS INDICATE THAT THE 4 THSD FT LOW CLOUD
SHIELD PUSHING NORTHEAST SHOULD ONLY BRIEFLY AFFECT MAINLY THE FAR
SOUTHEAST BEFORE HEADING OFF TO THE EAST. RUC AND NAM SATURATE THE
LOWER LEVELS LATER THIS MORNING ON THE RUC VERSUS THIS AFTERNOON
ON THE NAM. CURRENT TRENDS ON SATELLITE SUPPORT THE SLOWER NAM
WITH LOW CLOUDS FARTHER BEHIND THE COLD FRONT. NAM THEN DISSIPATES
THIS CLOUD LAYER WITH COLD AIR ADVECTION AND DRYING LATER TONIGHT.
HOWEVER MODELS TEND TO OVERDO THE DRYING SO WILL DELAY THE
CLEARING A LITTLE.
.SHORT TERM...TUESDAY THROUGH WEDNESDAY NIGHT...FORECAST CONFIDENCE
MEDIUM.
NAM/CANADIAN AND GFS/ECMWF SHOWING DIFFERENT PATHS FOR THE SURFACE
LOW FOR TUESDAY INTO WEDNESDAY. THE NAM/CANADIAN SHOWS IT SHIFTING
FROM EAST CENTRAL OKLAHOMA TO SOUTHWEST MISSOURI TUESDAY...THEN TO
NORTH CENTRAL ILLINOIS TUESDAY NIGHT...THEN NORTHEAST INTO LAKE
HURON WEDNESDAY. THIS PATH BRINGS QPF INTO THE AREA TUESDAY
AFTERNOON AND EVENING...THEN ANOTHER SHOT ON WEDNESDAY.
GFS/ECMWF SHOWS THE LOW MOVING FROM EAST CENTRAL OKLAHOMA TO FAR
SOUTHERN MISSOURI TUESDAY...THEN TO NORTHERN INDIANA/NORTHWEST
OHIO TUESDAY NIGHT..BEFORE SHIFTING INTO THE NORTHEASTERN UNITED
STATES WEDNESDAY. THIS PATH BRINGS QPF INTO FAR SOUTHERN PORTIONS
OF THE AREA TUESDAY AFTERNOON...THEN TO THE SOUTHEAST HALF OF THE
AREA TUESDAY NIGHT. MOST QPF SHIFTS EAST ON WEDNESDAY.
ALL MODELS SHOWING WARM AIR ADVECTION TUESDAY AFTERNOON ACROSS THE
AREA...WITH IT CONTINUING TUESDAY NIGHT ON THE NAM/CANADIAN. THE
GFS/ECMWF KEEP THE WARM AIR ADVECTION MAINLY EAST OF THE AREA
TUESDAY NIGHT. MODELS ALSO BRING UPPER LOW TO EASTERN KANSAS
TUESDAY...THEN INTO NORTHERN ILLINOIS TUESDAY NIGHT...BEFORE
SHIFTING EAST WEDNESDAY.
AREA FORECAST SOUNDINGS ON THE NAM AND GFS INDICATED THAT ANY
PRECIPITATION ON TUESDAY WOULD BEGIN AS A LIGHT RAIN AND LIGHT
SNOW MIX...BEFORE THE ICE CRYSTAL INTRODUCTION IN THE SATURATED
PORTION OF THE AIR COLUMN DIMINISHES BY 00Z WEDNESDAY.
THEN...POTENTIAL FOR LIGHT FREEZING RAIN COMES INTO THE AREA AND
LASTS TUESDAY NIGHT...PERHAPS INTO EARLY WEDNESDAY. AREAS IN THE
FAR EAST MAY WARM ENOUGH TO BRING A MIX OF LIGHT FREEZING RAIN AND
LIGHT RAIN...OR ALL LIGHT RAIN. TUESDAY NIGHT INTO EARLY WEDNESDAY
MAY HAVE TO BE WATCHED FOR A FREEZING RAIN ADVISORY IF THESE
CONDITIONS LINGER IN THE MODELS IN SUBSEQUENT RUNS. SOME
UNCERTAINTY EXISTS...WITH BETTER SHOT BEING WITH THE STRONGER
SURFACE LOW IN THE NAM/CANADIAN MODELS THAN WEAKER LOW WITH THE
GFS/ECMWF.
NAM/CANADIAN SEEM TO SHOW AN ENHANCED AREA OF QPF ACROSS
SOUTHEASTERN SECTIONS OF THE AREA FOR THE 6 HOURS ENDING AT 18Z
WEDNESDAY. THIS SEEMS TO BE DRIVEN BY Q VECTOR CONVERGENCE.
GFS/ECMWF NOT SHOWING THIS...AND HAVE BEST LIFT EAST OF THE
REGION. AREA FORECAST SOUNDINGS SHOWING SUPPORT IN THE MORNING FOR
LIGHT FREEZING RAIN/LIGHT SNOW/LIGHT RAIN MIX IN THE WEST...WITH
MORE LIGHT RAIN IN THE FAR EAST WITH MILDER TEMPERATURES.
CONTINUED TO MENTION POPS IN THIS PERIOD...WITH SOME UNCERTAINTY
ON PRECIPITATION TYPES GIVEN THE MODEL DIFFERENCES. MILD
TEMPERATURES OVERALL CONTINUE FOR TUESDAY THROUGH WEDNESDAY.
QUIET WEATHER RETURNS FOR WEDNESDAY NIGHT...AHEAD OF ADVANCING
COLD FRONT. MILD TEMPERATURES ARE EXPECTED TO CONTINUE.
.LONG TERM...THURSDAY THROUGH CHRISTMAS DAY...FORECAST CONFIDENCE
MEDIUM.
GFS/ECMWF BOTH SHOW A COLD FRONT SHIFTING SOUTHEAST THROUGH THE
REGION THURSDAY. ECMWF HINTING AT SOME LIGHT QPF WITH THIS
FEATURE...WITH THE GFS SHOWING LITTLE TO NONE. FOR NOW...LEANED
TOWARD THE CONSENSUS FORECAST AND LEFT LOW POPS FOR LIGHT SNOW
SHOWERS. MILD TEMPERATURES SHOULD LINGER.
MODELS THEN SHOW SIMILAR AND DIFFERENT TRENDS THURSDAY NIGHT
THROUGH CHRISTMAS DAY ACROSS THE REGION. THEY BOTH DO SHOW HIGH
PRESSURE PASSING TO THE NORTH OF THE REGION THURSDAY NIGHT AND
FRIDAY...WITH ITS RIDGE AXIS SHIFTING INTO THE AREA SATURDAY. THE
ECMWF TRIES TO KEEP AN INTACT SHORTWAVE TROUGH EXTENDING FROM THE
WESTERN GREAT LAKES TO THE CENTRAL AND SOUTHERN PLAINS STATES
FRIDAY. THE GFS KEEPS MORE OF A NORTHERN AND SOUTHERN STREAM
SEPARATELY...WITH AN UPPER LOW MOVING TOWARD THE AREA FRIDAY INTO
FRIDAY NIGHT.
THE GFS IS MUCH FURTHER SOUTH WITH THE BASE OF THE SHORTWAVE
TROUGH FRIDAY NIGHT. ANOTHER SHORTWAVE TROUGH THEN MOVES INTO THE
REGION FOR SATURDAY NIGHT INTO CHRISTMAS DAY. NOT MUCH QPF IN
MODELS WITH THIS FEATURE.
FOR NOW...WILL USE CONSENSUS APPROACH TO GRIDS GIVEN THE
DISAGREEMENT WITH FEATURES. THIS SHOULD KEEP THE FORECAST DRY FOR
NOW...WITH TEMPERATURES NEAR SEASONAL NORMALS.
&&
.AVIATION/12Z TAFS/...
THE WIND SHEAR POTENTIAL EARLY THIS MORNING ENDS AS THE 850MB JET
MAX OF 50 KNOTS PUSHES EAST INTO THE EASTERN GREAT LAKES.
THEN MAIN QUESTION IS STRATUS POTENTIAL. 4 THSD FT LOW CLOUDS MOVE
OFF WITH THE LOW LEVEL JET EARLY THIS MORNING. RUC AND NAM
SATURATE THE LOWER LEVELS LATER THIS MORNING ON THE RUC...WHICH
WOULD IMPLY IFR CIGS...VS THIS AFTERNOON ON THE NAM WHICH WOULD
MORE LIKELY BE MVFR CIGS. CURRENT TRENDS ON SATELLITE SUPPORT THE
SLOWER NAM WITH MVFR CIGS AFTER THE COLD FRONT. NAM SOUNDINGS THEN
DISSIPATES THE LOW LEVEL CLOUDS WITH COLD AIR ADVECTION AND DRYING
LATER TONIGHT. HOWEVER MODELS TEND TO OVERDO THE DRYING.
&&
.MARINE...
LOW PRESSURE NORTHEAST OF LAKE SUPERIOR WILL MOVE EAST. SMALL
CRAFT ADVISORY SOUTHWEST WINDS SHOULD DIMINISH THIS MORNING.
NORTH TO NORTHEAST WINDS MAY APPROACH SMALL CRAFT LEVELS THIS
AFTERNOON AND INTO THE EVENING BEHIND A TRAILING COLD FRONT. THIS
WILL HAVE TO BE WATCHED FOR ANOTHER POSSIBLE SMALL CRAFT ADVISORY.
&&
.MKX WATCHES/WARNINGS/ADVISORIES...
WI...NONE.
LM...SMALL CRAFT ADVISORY UNTIL 8 AM CST THIS MORNING FOR LMZ643>646.
&&
$$
TODAY/TONIGHT AND AVIATION/MARINE...HENTZ
TUESDAY THROUGH SUNDAY...WOOD
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
1123 PM CST SUN DEC 18 2011
.SHORT TERM...THROUGH TUESDAY NIGHT
227 PM CST SUN DEC 18 2011
MAIN FORECAST CONCERN IS WITH THE PRECIPITATION CHANCES AND TYPES
TUESDAY AND TUESDAY NIGHT.
SURFACE ANALYSIS THIS AFTERNOON SHOWS AN AREA OF LOW PRESSURE OVER
SOUTHWEST ONTARIO WITH A COLD FRONT EXTENDING SOUTHWEST THROUGH
NORTH DAKOTA.
THE COLD FRONT WILL SLIDE ACROSS THE REGION OVERNIGHT. AS IT
DOES...THE 18.12Z NAM AND 18.18Z RUC SUGGEST THERE WILL BE A
RIBBON OF LOW LEVEL MOISTURE BEHIND THE FRONT THAT SHOULD BE
SUFFICIENT TO ALLOW SATURATION TO OCCUR. THIS SHOULD RESULT IN A
BAND OF STRATUS CLOUDS DEVELOPING ACROSS THE REGION AND HAVE
RAISED THE CLOUD COVER TO HANDLE THIS. OBSERVATIONS ACROSS
SASKATCHEWAN AND MANITOBA DO INDICATE THE EXISTENCE OF THIS
STRATUS ALREADY. THE NAM BUFKIT SOUNDINGS INDICATE SOME VERTICAL
MOTION THROUGH THIS SATURATED LAYER SUGGESTING THE POTENTIAL FOR
SOME DRIZZLE. HOWEVER...THE RUC DOES NOT SHOW THIS AND WILL LEAVE
OUT THE MENTION OF ANY DRIZZLE.
THE FRONT WILL BECOME STATIONARY SOUTH OF THE AREA MONDAY NIGHT AS
THE UPPER LEVEL LOW OVER THE SOUTHWEST STARTS TO EJECT OUT TO THE
NORTHEAST. AS THIS SYSTEM COMES OUT...BOTH THE NAM AND GFS BRING
BETWEEN 4 AND 8 PVU/S OF VORTICITY ADVECTION IN THE 500-300 MB
LAYER ACROSS THE SOUTHERN PARTS OF THE FORECAST AREA TUESDAY AND
TUESDAY NIGHT. THIS IS EXPECTED TO RESULT IN WEAK TO MODERATE QG
CONVERGENCE OCCURRING ACROSS THE FAR SOUTHERN PARTS OF THE
FORECAST AREA. THERE SHOULD ALSO BE SOME WEAK FRONTOGENESIS IN THE
850-500 MB LAYER OF THE SAME AREA. THERE IS ENOUGH OF A CONSENSUS
IN ALL THE MODELS TO BRING THE PRECIPITATION CHANCES TO ABOUT THE
INTERSTATE 90 CORRIDOR TUESDAY AFTERNOON AND NIGHT. BUFKIT
SOUNDINGS FROM BOTH THE NAM AND GFS SUGGEST THERE MAY NOT BE A LOT
OF ICE PRESENT IN THE CLOUDS AS THIS SYSTEM COMES THROUGH. THE
SOUNDINGS SUGGEST CLOUD TOP TEMPERATURES MAY BE IN THE -10 TO -12C
RANGE AND THERE COULD ALSO BE A BIT OF A WARM LAYER ALOFT AT TIMES
AS WELL. HAVE THUS ADDED IN SOME PROBABILITIES OF FREEZING RAIN
AND WILL HAVE A MIXTURE OF RAIN...SNOW AND FREEZING RAIN. ACTUAL
PRECIPITATION AMOUNTS SHOULD BE VERY LIGHT AND ANY SNOW OR ICE
ACCUMULATIONS THAT OCCUR SHOULD NOT AMOUNT TO MUCH.
.LONG TERM...WEDNESDAY THROUGH SUNDAY
227 PM CST SUN DEC 18 2011
AS THE SYSTEM PULLS AWAY FROM THE AREA WEDNESDAY...THERE COULD
STILL BE A LITTLE BIT OF LINGERING PRECIPITATION ACROSS THE FAR
SOUTHEASTERN PARTS OF THE FORECAST AREA. THE NEXT NORTHERN STREAM
SHORT WAVE TROUGH IS EXPECTED TO COME ACROSS THE UPPER MIDWEST
WEDNESDAY NIGHT AND THURSDAY. MODELS HAVE BEEN INCONSISTENT ON
WHETHER THIS WILL BE ENOUGH TO PRODUCE SOME LIGHT SNOW AS THE WEAK
COLD FRONT COMES THROUGH. FOR NOW...WILL STAY WITH THE CURRENT
MODEL CONSENSUS GRIDS SHOWING THE SNOW CHANCES FARTHER NORTH
CLOSER TO THE SHORT WAVE TROUGH...BUT COULD SEE LATER FORECASTS
ADDING IN SOME SNOW CHANCES FOR THIS SYSTEM. ANOTHER WAVE WILL BE
DROPPING INTO THE UPPER MIDWEST NEXT SUNDAY AND WILL HAVE SOME
SMALL SNOW CHANCES ACROSS THE NORTH WITH THIS SYSTEM.
&&
.AVIATION...THROUGH 06Z TUESDAY
1123 PM CST SUN DEC 18 2011
THE MAIN FOCUS CONTINUES TO BE ON THE COLD FRONT PASSAGE TIMING
AND WHEN THE LOW STRATUS DECK GETS INTO THE TAF REGION.
CURRENTLY...THIS COLD FRONT EXTENDS FROM JUST SOUTH OF LAKE
SUPERIOR DOWN TO SIOUX FALLS SOUTH DAKOTA. THIS STRATUS DECK IS
LAGGING BEHIND THE FRONTAL PASSAGE AND IS MAINLY MVFR BETWEEN 1KFT
TO 2KFT THOUGH A FEW OBS HAVE BEEN REPORTING 800FT CEILINGS. BASED
ON THESE TRENDS AND 19.03Z RUC SOUNDINGS FROM LSE/RST...HAVE
BACKED OUT OF THE IFR CEILING FORECAST AND BROUGHT THEM UP TO LOW
END MVFR TOWARD 10/11Z. WITH A LITTLE DEEPER MIXING AS THE DAY
PROGRESSES...WOULD EXPECT THESE CEILINGS TO GRADUALLY CLIMB THOUGH
STAY MVFR. WHEN/IF SKIES CLEAR OUT IS THE NEXT QUESTIONS WITH MUCH
OF THE FORECAST GUIDANCE SUGGESTING THAT THE CLOUDS WILL CLEAR BY
MID AFTERNOON. THIS MAY BE QUITE OPTIMISTIC THOUGH WITH A SHALLOW
INVERSION HOLDING ON INTO TOMORROW NIGHT. THUS...HAVE KEPT CIGS
AROUND THROUGH THE REST OF THE FORECAST PERIOD BUT ENDED THE
HIGHER GUSTS BY DUSK.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
227 PM CST SUN DEC 18 2011
WI...NONE.
MN...NONE.
IA...NONE.
&&
$$
SHORT TERM...04
LONG TERM...04
AVIATION...HALBACH
AREA FORECAST DISCUSSION
NWS CHEYENNE WY
250 AM MST MON DEC 19 2011
.SHORT TERM...TODAY THROUGH WEDNESDAY NIGHT.
TODAY...COLD FRONT QUICKLY PASSED SOUTHWARD ACROSS OUR COUNTIES
EARLIER TONIGHT WITH DECENT COLD AIR ADVECTION ONGOING WITH 2-4 MB 3
HOURLY PRESSURE RISES IN THE WAKE OF THE COLD FRONT. AS INPUT BY DAY
SHIFT FORECAST...WILL MAINTAIN PATCHY FREEZING DRIZZLE ACROSS OUR
PANHANDLE COUNTIES SOUTH OF SCOTTSBLUFF TO ALLIANCE AS THE
ATMOSPHERE SUGGEST FAVORABLE CONDITIONS. LOW AND MID LEVELS WILL
CONTINUE TO SATURATE THIS MORNING AND WITH FAVORABLE NORTHEAST TO
EAST UPSLOPE...AND DYNAMICS FROM PASSING SHORTWAVE TROUGH
ALOFT...WILL INCLUDE 60 TO 100 PERCENT POPS FOR SNOW THIS MORNING
ALONG AND JUST EAST OF THE LARAMIE RANGE WITH LESSER POPS FURTHER
EAST AND WEST DUE TO DRY AIR AT LOW LEVELS AND DOWNSLOPING EAST
WINDS WEST OF THE MOUNTAINS AND SNOW SHADOW EFFECTS. AREAS OF FOG
DEVELOP AS THE TEMPERATURE AND DEWPOINT SPREADS NARROW. SNOWFALL
ACCUMULATIONS LESS THAN 2 INCHES DUE TO PROGRESSIVE NATURE OF THE
SYSTEM AND LIMITED QPF. CHANCES FOR SNOW DECREASE SIGNIFICANTLY THIS
AFTERNOON...THOUGH REMAIN HIGH ACROSS THE SOUTHERN LARAMIE RANGE DUE
TO PERSISTENT EASTERLY UPSLOPE. MUCH COLDER THAN SUNDAY WITH CLOUDS
AND IN THE COLD AIRMASS BEHIND THE FRONT.
TONIGHT...DECREASING CLOUDS AND LIGHT WINDS WILL MAKE FOR A CHILLY
NIGHT WITH COLDEST CONDITIONS ACROSS THE LARAMIE VALLEY. WEAK LEE
TROUGHING DEVELOPS BUT SHOULD NOT HAVE MUCH EFFECT ON LOW
TEMPERATURES.
TUESDAY...SLOW WARMING TREND IN BETWEEN SYSTEMS. WITH SOME SUNSHINE
AND SURFACE LEE TROUGHING INDUCING DOWNSLOPE WARMING...WILL SEE HIGH
TEMPERATURES IN THE 20S WEST AND 30S EAST.
TUESDAY NIGHT...NOT AS COLD AS MONDAY NIGHT AS MID AND HIGH CLOUDS
INCREASE IN ADVANCE OF THE NEXT STRONGER SHORTWAVE TROUGH ALOFT
APPROACHING FROM IDAHO AND WESTERN MONTANA.
WEDNESDAY...RATHER IMPRESSIVE SHORTWAVE TROUGH ALOFT CONTINUES TO
DIG ACROSS IDAHO AND WESTERN WYOMING SENDING ANOTHER COLD FRONT
ACROSS OUR COUNTIES IN THE AFTERNOON. THE NAM SHOWS A DEEPLY
SATURATED LAYER DEVELOPING IN THE AFTERNOON ACROSS OUR COUNTIES IN
THE WAKE OF THE COLD FRONT WHILE THE GFS IS SLOWER IN THE
EVOLVEMENT. NAM TENDS TO DO BETTER IN THESE SITUATIONS AND THUS WILL
FOLLOW ITS SOLUTION BRINGING CHANCE OF SNOW ACROSS ALL OUR COUNTIES
IN THE AFTERNOON...WITH 50 TO 100 PERCENT POPS NORTH OF A RAWLINS TO
CHADRON LINE WITH DEEPLY SATURATED AIRMASS LIFTED BY DYNAMICS AND
OROGRAPHICS.
WEDNESDAY NIGHT...SHORTWAVE TROUGH ALOFT MOVES ACROSS WESTERN
COLORADO WITH DYNAMICS AND OROGRAPHICS PROVIDING THE LIFT OF OUR
SATURATED AIRMASS TO PRODUCE FAIRLY WIDESPREAD LIGHT SNOW OVER OUR
COUNTIES...WITH MOST COVERAGE OVER THE FAVORED UPSLOPE LOCATIONS
NEAR THE SOUTHERN LARAMIE RANGE OF WESTERN LARAMIE COUNTY.
.LONG TERM...THURSDAY THROUGH MONDAY
19/00Z ECMWF AND GFS MODEL RUNS IN VERY GOOD AGREEMENT ON TRACK OF
LOW OVER UTAH THURSDAY MORNING POSITIONING OF PRECIPITATION OVER
WYOMING. GFS MORE BULLISH ON QPFS WITH EC MORE CONSERVATIVE. AM
BECOMING A LITTLE CONCERNED THOUGH WITH ACCUMULATING SNOWFALL AS
THIS TRACK IS A FAVORABLE PATTERN FOR US TO SEE SIGNIFICANT
SNOWFALL. LATER SHIFTS WILL NEED TO WATCH TO SEE IF THE LOW SLOWS
DOWN OR SHIFTS SLIGHTLY NORTH OF ITS CURRENT FORECAST TRACK.
LATEST TRACK ON BOTH THE GFS AND ECMWF HAS THE LOW TRACKING FROM
CENTRAL UTAH INTO SOUTHERN COLORADO AND FINALLY INTO NORTHERN NEW
MEXICO THURSDAY AFTERNOON. FOR NOW...HAVE SNOW ACCUMULATIONS OF 3
TO 5 INCHES FROM WEDNESDAY NIGHT THROUGH THURSDAY FOR MUCH OF THE
CWA WITH 10 TO 14 INCHES IN THE SNOWY AND SIERRA MADRE RANGES.
SNOW COMES TO AN END THURSDAY AFTERNOON WITH RIDGING MOVING INTO
THE AREA FROM THE NORTH. WESTERLY WINDS RETURN FRIDAY WITH 700MB
TEMPERATURES INCREASING FROM -14C THURSDAY AFTERNOON TO AROUND -6C
FRIDAY AFTERNOON. TEMPERATURES WILL BE TRICKY FRIDAY AND DEPENDS A
LOT ON RESIDING SNOW FROM THURSDAYS STORM. KEPT TEMPERATURES FAIRLY
COOL WITH LOW 30S FOR HIGHS EAST OF THE LARAMIE RANGE AND LOW 20S WEST.
LOOKS LIKE ANOTHER WEAK SHORTWAVE AND SURFACE COLD FRONT TO TRACK
THROUGH SOUTHEAST WYOMING SATURDAY. 700MB WINDS REALLY INCREASE
WITH THIS SYSTEM WITH GFS FORECASTING WINDS OF 50+KTS FRIDAY
AFTERNOON INTO SATURDAY MORNING. 700MB CRAIG TO CASPER HGT
GRADIENT AROUND 60 METERS AS WELL ON THE GFS DURING THAT TIME. DID
GO AHEAD AND INCREASE WIND SPEEDS FROM THURSDAY NIGHT THROUGH
FRIDAY NIGHT WITH THIS SYSTEM AND LATER SHIFTS WILL NEED TO WATCH
FOR WIND HIGHLIGHTS...ESPECIALLY FOR OUR WIND PRONE AREAS. WILL
ADD HIGH WIND POTENTIAL IN THIS MORNINGS HWO AS WELL.
PRETTY COLD WEEKEND AS 700MB TEMPERATURES FALL BACK DOWN TO -14 TO
-18C. LOOKING PROBABLY AT SINGLE DIGIT LOWS AND HIGHS STRUGGLING
TO GET ABOVE FREEZING. COULD BE COLDER DEPENDING ON ANY EXISTING
SNOW PACK FROM THURSDAYS STORM AS WELL.
&&
.AVIATION...06Z TAFS
LATEST STRATUS SATELLITE IMAGERY SHOWING BAND OF LOW CLOUDS
RAPIDLY MOVING SOUTH OUT OF SOUTH DAKOTA AND NORTHEASTERN WYOMING.
LATEST HRRR FORECAST SHOWS LIFR CONDITIONS INTO THE NORTHERN
PANHANDLE BY 08Z...QUICKLY MOVING SOUTH TO COVER THE ENTIRE
PANHANDLE BY 11Z. UPSLOPING WINDS WILL BRING IFR/LIFR CONDITIONS
INTO CHEYENNE SHORTLY THEREAFTER. STRATUS LOOKS TO STAY IN AT
LEAST UNTIL THIS AFTERNOON AND COULD HOLD ON INTO THIS EVENING
ACROSS THE PANHANDLE AND AT KCYS. WEST WINDS RETURN LATE THIS
EVENING AND STRATUS SHOULD BREAK OUT COMPLETELY AT THAT TIME.
&&
.FIRE WEATHER...
NO FIRE WEATHER CONCERNS. HIGHER MINIMUM AFTERNOON
RELATIVE HUMIDITIES TODAY IN THE WAKE OF THE COLD FRONT.
&&
.CYS WATCHES/WARNINGS/ADVISORIES...
WY...NONE.
NE...NONE.
&&
$$
SHORT TERM/FIRE WEATHER...RUBIN
LONG TERM/AVIATION...CLAYCOMB
AREA FORECAST DISCUSSION
NWS CHEYENNE WY
1022 PM MST SUN DEC 18 2011
.AVIATION...06Z TAFS
LATEST STRATUS SATELLITE IMAGERY SHOWING BAND OF LOW CLOUDS
RAPIDLY MOVING SOUTH OUT OF SOUTH DAKOTA AND NORTHEASTERN WYOMING.
LATEST HRRR FORECAST SHOWS LIFR CONDITIONS INTO THE NORTHERN
PANHANDLE BY 08Z...QUICKLY MOVING SOUTH TO COVER THE ENTIRE
PANHANDLE BY 11Z. UPSLOPING WINDS WILL BRING IFR/LIFR CONDITIONS
INTO CHEYENNE SHORTLY THEREAFTER. STRATUS LOOKS TO STAY IN AT
LEAST UNTIL THIS AFTERNOON AND COULD HOLD ON INTO THIS EVENING
ACROSS THE PANHANDLE AND AT KCYS. WEST WINDS RETURN LATE THIS
EVENING AND STRATUS SHOULD BREAK OUT COMPLETELY AT THAT TIME.
CLAYCOMB
&&
PREV DISCUSSION.../ISSUED 303 PM MST SUN DEC 18 2011/
SHORT TERM...TONIGHT THROUGH TUESDAY NIGHT...
PRIMARY FORECAST CHALLENGE WILL CENTER AROUND A COLD FRONTAL
PASSAGE AND ITS RESULTANT IMPACT AS IT PUSHES THROUGH THE CWA
LATER TONIGHT THROUGH EARLY MONDAY AFTERNOON. THE SPLIT FLOW
PATTERN WILL CONTINUE THROUGH THE PERIOD AS A NORTHERN STREAM
SHORTWAVE KICKS THE CLOSED LOW CURRENTLY OVR SW ARIZONA INTO THE
SOUTHERN PLAINS LATER MONDAY AND TUESDAY. FORTUNATELY THE IMPACT
OF THE THIS SOUTHERN STREAM SYSTEM WILL BE CONFINED WELL SOUTH OF
THE CWA. THAT SAID...THE NRN STREAM SHORTWAVE WILL DRAG A COLD
FRONT FROM NORTH TO SOUTH THROUGH THE AREA LATER TONIGHT. SFC
ANALYSIS AT 20Z SHOWS THE SFC COLD FRONT EXTENDING FROM CENTRAL
NORTH DAKOTA INTO CENTRAL MONTANA AND BEING PUSHED SOUTH BY 5MB
3-HOURLY PRESSURE PRESSURE RISES. MODELS ARE CONSISTENT IN PUSHING
THIS COLD FRONT INTO EAST CENTRAL WYOMING/NRN NEBRASKA PANHANDLE
BY AROUND SUNSET AND CLEARING THE ENTIRE CWA BY AROUND MIDNIGHT.
WINDS WILL TURN NORTH/NORTHEASTERLY IN THE WAKE OF THE COLD FRONT.
SO EXPECT PERIOD OF FAVORABLE OROGRAPHIC ASCENT FOR LARAMIE RANGE
AND ADJACENT EAST/NORTH PLAINS LOCATIONS. HAVE ALSO SPREAD
PRECIPITATION CHANCES A BIT FURTHER EAST INTO THE PANHANDLE AS
WELL...ESPECIALLY FOR FAVORED AREAS NORTH OF THE PINE RIDGE. PROGD
WRN NEBRASKA BUFKIT RAOBS SHOW A NEARLY SATURATED POST-FRONTAL
PBL...WITH DRY CONDITIONS ABOVE. SO HAVE INTRODUCED PATCHY
FREEZING DRIZZLE ACROSS THE WESTERN NEBRASKA PANHANDLE LATER
TONIGHT/EARLY MONDAY MORNING. HAVE ALSO TRENDED SNOW CHANCES
UPWARDS SOME ESPECIALLY ALONG THE LARAMIE RANGE AND THE
INTERSTATE 25 CORRIDOR. UPPER-LEVEL SUPPORT WILL BE LACKING WITH
THIS SYSTEM KEEPING SNOW RATES WEAK AND ACCUMULATIONS LIGHT. IN
GENERAL...EXPECT UP TO AN INCH OF NEW SNOW BELOW 7500 FEET WITH 1
TO 3 INCHES ABOVE BY MONDAY AFTERNOON. LARGE SCALE SUBSIDENCE
BENEATH A BUILDING 1032MB SFC HIGH WILL EFFECTIVELY SHUT OFF ANY
SNOW CHANCES BY MONDAY AFTERNOON. A MUCH DRIER AIR MASS WILL
RESULT IN BENIGN CONDITIONS FOR MONDAY NIGHT THROUGH TUESDAY
NIGHT.
AFTER AN UNSEASONABLY WARM WEEKEND...TEMPERATURES WILL TURN
ABRUPTLY COLDER BEHIND TONIGHTS COLD FRONT. H7 TEMPERATURES OF
AROUND 3C TODAY WILL FALL TO AROUND -10C BY MONDAY AFTERNOON. SO
HIGHS WILL ONLY CLIMB INTO THE 20S AND LOW 30S. WARM AIR ADVECTION
WILL RESULT IN HIGH TEMPERATURES THAT WILL MODERATE BACK INTO THE
30S AND LOW 40S FOR TUESDAY.
LONG TERM...WEDNESDAY THROUGH CHRISTMAS DAY...
THE MAIN CONCERN OVER THE EXTENDED PERIOD IS THE WINTER STORM
FORECASTED TO AFFECT THE AREA LATE WEDNESDAY THROUGH THURSDAY. THE
MEDIUM RANGE MODELS HAVE COME INTO BETTER AGREEMENT...SHOWING A
MIDLEVEL TROUGH AMPLIFYING AND DIGGING SOUTHEAST OVER IDAHO AND
UTAH ON WEDNESDAY. THE MIDLEVEL TROUGH ATTEMPTS TO CLOSE OFF NORTH
OF THE FOUR CORNERS REGION ON WEDNESDAY NIGHT...WITH LARGE SCALE
LIFT AND MIDLEVEL Q-VECTOR CONVERGENCE OVER SOUTHEAST WYOMING. IN
THE LOWER LEVELS...850-700 MB WINDS ARE PROGGED TO TURN EASTERLY
WITH A GOOD PERIOD OF UPSLOPE FROM 00Z TO 12Z THURSDAY ALONG THE
LARAMIE RANGE. HIGHS WILL STRUGGLE TO GET OUT OF THE MID 20S EAST
OF THE LARAMIE RANGE ON THURSDAY WITH CLOUD COVER...SFC
UPSLOPE...AND COLD AIR ADVECTION. THE GFS AND ECMWF CLOSE OFF THE
SYSTEM MORE COMPARED TO THE CANADIAN...HOWEVER ALL MODELS SHOW THE
TROUGH PUSHING OFF TO THE SOUTHEAST BY LATE THURSDAY. WITH THE
INCREASE IN MODEL AGREEMENT OVER THE EVOLUTION OF THIS
SYSTEM...THE MAIN CHANGE IN THIS FORECAST PACKAGE WAS TO INCREASE
POPS OVER THE PLAINS AND ESPECIALLY OVER THE HIGHER
ELEVATIONS/FOOTHILLS FROM LATE WEDNESDAY THROUGH MIDDAY THURSDAY.
SOME MODERATE ACCUMULATIONS LOOK INCREASINGLY POSSIBLE WITH THIS
STORM SYSTEM. CONDITIONS WILL DRY OUT BEHIND THE TROUGH ON
FRIDAY...HOWEVER SFC TEMPERATURES THROUGH SUNDAY WILL BE BELOW
NORMAL WITH 700 MB TEMPERATURES AROUND -12C.
&&
FIRE WEATHER...
NO FIRE WEATHER CONCERNS THROUGH THE WEEK. AFTER A DRY AND
UNSEASONABLY WARM SUNDAY...A COLD FRONT WILL DROP SOUTH THROUGH
THE DISTRICT THIS EVENING TURNING TEMPERATURES SHARPLY COOLER FOR
MONDAY. ALSO ANTICIPATE CLOUDY CONDITIONS ALONG WITH A PERIOD OF
SNOW OR FREEZING DRIZZLE ACROSS THE AREA LATE TONIGHT THROUGH
MONDAY MORNING. THIS PRECIPITATION WILL WANE BY LATE
MONDAY...GIVING WAY TO DRY CONDITIONS AND MODERATING TEMPERATURES
ON TUESDAY. ANOTHER STORM SYSTEM WILL BRING ADDITIONAL SNOW
CHANCES ON WEDNESDAY NIGHT AND THURSDAY.
&&
.CYS WATCHES/WARNINGS/ADVISORIES...
WY...NONE.
NE...NONE.
&&
$$
SHORT TERM/FIRE WEATHER...HAHN
LONG TERM/AVIATION...FINCH
AREA FORECAST DISCUSSION
NWS NEW YORK NY
1004 AM EST MON DEC 19 2011
.SYNOPSIS...
A HIGH PRESSURE RIDGE SHIFTS OFFSHORE TODAY. A COLD FRONT WILL
MOVE THROUGH TONIGHT. HIGH PRESSURE BUILDS OVER THE AREA TUESDAY. A
WARM FRONT APPROACHES FROM THE SOUTH TUESDAY NIGHT...THEN LIFTS TO
THE NORTH WEDNESDAY...FOLLOWED BY A COLD FRONT WEDNESDAY
NIGHT...AS AN AREA OF LOW PRESSURE PASSES TO OUR NORTH. HIGH
PRESSURE THEN BUILDS IN TO OUR NORTH THURSDAY THROUGH SUNDAY...AS
A COUPLE OF LOW PRESSURE SYSTEMS PASS TO OUR SOUTH FRIDAY AND THEN
LATE NEXT WEEKEND.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
15Z UPDATE TO MAKE JUST MINOR ADJUSTMENTS TO TEMPS AND DEW POINTS
BASED ON CURRENT OBS THIS MORNING. SOUTHWEST FLOW WILL HELP TEMPS
MODERATE ACROSS THE REGION THIS MORNING. OTHERWISE...FORECAST
GENERALLY ON TRACK.
A HIGH PRESSURE RIDGE LOCATED RIGHT ALONG THE EAST COAST EARLY
THIS MORNING WILL SHIFT OFFSHORE TODAY...ALLOWING RETURN FLOW TO
DEVELOP OVER THE REGION. LOW PRESSURE EMBEDDED IN A STRONG
JETSTREAM ACROSS SOUTHERN CANADA WILL QUICKLY SHIFT EASTWARD
ACROSS QUEBEC...DRAGGING A COLD FRONT ACROSS THE GREAT LAKES
REGION. THE PRESSURE GRADIENT WILL INCREASE QUICKLY TODAY AS THE
LOW PASSES TO OUR NORTH...WITH GUSTY WINDS DEVELOPING BY LATE
MORNING AND CONTINUING THROUGH THE AFTERNOON. 00Z NAM SUGGESTS
LIGHT PRECIP DEVELOPING OVER THE REGION BY LATE AFTERNOON WITH A
WEAK VORT MAX MOVING THROUGH...BUT SIDED WITH 00Z GFS/ECMWF WHICH
KEEP ANY PRECIP NORTH AND WEST OF THE REGION.
WARM AIR ADVECTION DEVELOPS WITH THE HIGH OFFSHORE...ENABLING
TEMPERATURES TO CLIMB INTO THE LOW TO MID 40S AREA WIDE. MAV/MET
GUIDANCE IN GOOD AGREEMENT...AND WERE BLENDED FOR TEMPS.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH TUESDAY NIGHT/...
MODEL CONSENSUS INDICATES COLD FRONT WILL BE LOCATED OVER
WESTERN/NORTHERN NY STATE BY EARLY THIS EVENING...THEN QUICKLY SWEEP
TO THE SOUTHEAST AND MOVE THROUGH THE REGION OVERNIGHT. WITH ZONAL
FLOW ALOFT MOISTURE WILL BE LIMITED...BUT ENOUGH LAKE MOISTURE MAY
ALLOW FOR SOME SPRINKLES AND/OR FLURRIES...WITH POTENTIAL FOR LIGHT
SNOW OVER THE LOWER HUDSON VALLEY. BL TOO WARM FOR FLAKES NEAR THE
COASTS INITIALLY...BUT AS THE CWA GETS INTO THE RR QUAD OF THE H3
150 PLUS KT H3 JET AFT MIDNIGHT...A FEW FLURRIES MAY MIX IN WITH
ANY SPRINKLES HERE AS WELL.
GUSTY WINDS DIMINISH THIS EVENING AS LOW-LEVEL INVERSION
DEVELOPS...BUT GUSTS MAY REDEVELOP BY EARLY TUESDAY MORNING AS
COOLER AIR ALOFT MOVES IN BEHIND THE FRONT.
MAV/MET BLENDED AGAIN FOR LOWS TONIGHT...WHICH WILL RANGE FROM THE
UPPER 20S OVER NORTHERN SECTIONS TO THE MID 30S NEAR THE COASTS.
ON TUESDAY...HIGH PRESSURE RIDGE DROPS FROM THE GREAT LAKES INTO
THE TRI-STATE AREA. WINDS DIMINISH AS THE HIGH BUILDS IN. HIGHS
GENERALLY IN THE LOW TO MID 40S.
&&
.LONG TERM /WEDNESDAY THROUGH SUNDAY/...
A PROGRESSIVE SPLIT FLOW ACROSS THE LOWER 48 GETS A BIT MORE
INTERESTING THIS WEEK AS SEVERAL SOUTHERN BRANCH LOWS INTERACT WITH
MARGINALLY COLD AIR ACROSS THE NE U.S. THE 00Z GFS AND ECMWF ARE IN
REMARKABLE AGREEMENT DURING THIS PERIOD...ALTHOUGH THERE ARE SOME
TIMING DIFFERENCES AS CAN BE EXPECTED. THE GFS IS THE MORE
PROGRESSIVE OF THE SOLUTIONS IN THE HANDLING OF EACH WAVE...WHICH
SEEMS TO MAKE SENSE BASED ON THE PROGRESSIVE NATURE OF THE UPPER
FLOW. AT THIS POINT IN TIME...IT IS TOO EARLY BE SPECIFIC WITH ANY
DETAILS...BUT THERE IS THE POTENTIAL FOR WINTRY WEATHER...
ESPECIALLY ACROSS THE INTERIOR.
THE FIRST STORM SYSTEM WILL EMERGE FROM THE MID MS VALLEY TUE NIGHT
AND TAKE A TRACK TO THE NORTH AND WEST OF THE FORECAST AREA WED.
PCPN AHEAD OF ITS WARM FRONT MAY DEVELOP IN THE OVERNIGHT HOUR TUE.
THE TIMING HERE IS CRITICAL AS THE COLD AIR WILL BE ERODING IN A
STRENGTHENING SOUTHERLY FLOW. COASTAL AREAS WILL BE ALL RAIN...BUT
THERE IS A POSSIBILITY OF A BRIEF WINTRY MIX ACROSS INLAND AREAS
PRIOR TO DAYBREAK. THE STEADIEST PCPN WILL FALL AS RAIN ON WED. THE
TRAILING COLD FRONT WILL THEN BRIEFLY DRY CONDITIONS OUT WED NIGHT
INTO THU. THE NEXT SYSTEM TAKES A TRACK FROM THE LOWER MS VALLEY
THU...NE TO OFF THE MID ATLANTIC COAST ON FRI. THIS SYSTEM TOO MAY
FEATURE A WINTRY MIX INLAND. VERTICAL TEMPERATURE PROFILES ARE
MARGINAL IN BOTH CASES WITH NO REAL GOOD SOURCE OF POLAR AIR. THE
FAST FLOW ACROSS THE NORTHERN TIER OF THE COUNTRY IS PREVENTING A
STRONG SOUTHWARD PUSH.
FINALLY...THE LAST STORM HAS THE POTENTIAL TO IMPACT THE AREA
CHRISTMAS EVE AND DAY. THE ECMWF HAS TRENDED TO A STRONGER LOW IN
COMPARISON TO THE GFS WITH A 989 MB LOW PASSING NEAR CAPE COD NEXT
SUNDAY. THE GFS IS ABOUT 20 MB WEAKER. A DECENT HIGH TO THE NORTH
FOR THIS GO AROUND MAY POSE A MORE SIGNIFICANT WINTER WEATHER
THREAT. ONCE AGAIN THOUGH...THERE WILL LIKELY BE SEVERAL CHANGES IN
THE FORECAST OUT THIS FAR. IT IS DEFINITELY WORTH KEEPING AN EYE ON.
TEMPERATURES WILL START OFF ABOVE NORMAL FOR THE MID WEEK
PERIOD...BUT THEN TRANSITION TO MORE SEASONABLE READINGS FOR THE END
OF THE WEEK INTO NEXT WEEKEND. HIGHS WILL TOP OUT IN THE LOWER 50S
WED AND THU...BUT THEN FALL TO AROUND 40 BY THE WEEKEND.
&&
.AVIATION /15Z MONDAY THROUGH FRIDAY/...
HIGH PRESSURE MOVES EAST WITH INCREASING SW FLOW. A COLD FRONT MOVES
THROUGH THE TERMINALS LATE TONIGHT. COULD BE A FEW
FLURRIES/SPRINKLES ACCOMPANYING THE FROPA...BUT NOT EXPECTED TO
MAKE RUNWAYS WET.
VFR TODAY. INCREASING SW GUSTS TODAY...SPORADIC THROUGH 17Z. LOW
CONFIDENCE AT THIS TIME ON WHEN GUSTS WILL SUBSIDE. COLD FROPA
BETWEEN 05Z AND 09Z TONIGHT WITH WINDS BECOMING NW.
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)
KJFK FCSTER COMMENTS: AMENDMENTS POSSIBLE TO INCREASE GUST
SPEEDS. LOW CONFIDENCE ON TIMING OF GUSTS DIMINISHING...OCNL
GUSTS MAY LINGER THROUGH 03Z WHILE DIMINISHING.
KLGA FCSTER COMMENTS: AMENDMENTS POSSIBLE TO INCREASE GUST
SPEEDS. LOW CONFIDENCE ON TIMING OF GUSTS DIMINISHING...OCNL
GUSTS MAY LINGER THROUGH 03Z WHILE DIMINISHING.
KEWR FCSTER COMMENTS: AMENDMENTS POSSIBLE TO INCREASE GUST
SPEEDS. LOW CONFIDENCE ON TIMING OF GUSTS DIMINISHING...OCNL GUSTS
MAY LINGER THROUGH 03Z WHILE DIMINISHING.
KTEB FCSTER COMMENTS: AMENDMENTS POSSIBLE TO INCREASE GUST
SPEEDS. LOW CONFIDENCE ON TIMING OF GUSTS DIMINISHING...OCNL GUSTS
MAY LINGER THROUGH 03Z WHILE DIMINISHING.
KHPN FCSTER COMMENTS: AMENDMENTS POSSIBLE TO INCREASE GUST
SPEEDS. LOW CONFIDENCE ON TIMING OF GUSTS DIMINISHING...OCNL GUSTS
MAY LINGER THROUGH 03Z WHILE DIMINISHING.
KISP FCSTER COMMENTS: AMENDMENTS POSSIBLE TO INCREASE GUST
SPEEDS. LOW CONFIDENCE ON TIMING OF GUSTS DIMINISHING...OCNL GUSTS
MAY LINGER THROUGH 02Z WHILE DIMINISHING.
OUTLOOK FOR 12Z TUESDAY THROUGH FRIDAY...
TUE...VFR.
TUE NIGHT AND WED...SUB VFR IN RAIN...A WINTRY MIX POSSIBLE
INLAND TUE NIGHT. BECOMING VFR WED NIGHT.
THU...VFR.
FRI...SUB-VFR POSSIBLE.
&&
.MARINE...
ISSUED GALE WARNING FOR EASTERN TWO OCEAN ZONES BEGINNING LATE
THIS MORNING AS CONFIDENCE INCREASES THAT GALE GUSTS WILL DEVELOP.
WINDS START LIGHT FROM THE SW THIS MORNING...BUT THE PRESSURE
GRADIENT WILL INCREASE QUICKLY AS HIGH PRESSURE MOVES EAST OF THE
WATERS AND A COLD FRONT APPROACHES FROM THE NORTHWEST. SCA
CONTINUES FOR ALL OTHER ZONES. ALSO CAN`T RULE OUT POTENTIAL FOR A
FEW GALE-FORCE GUSTS IN EASTERN LONG ISLAND SOUND AND THE WESTERN
OCEAN WATERS TODAY...AND THESE AREAS WILL NEED TO BE MONITORED.
OTHERWISE SCA CONTINUES OVER ALL WATERS NOT COVERED BY THE GALE
WARNING.
WINDS DIMINISH LATE TONIGHT BEHIND THE COLD FRONT AS HIGH PRESSURE
APPROACHES THE WATERS. SCA-LEVEL SEAS COULD LINGER INTO TUESDAY
ON THE FAR EASTERN COASTAL WATERS...OTHERWISE SUB-SCA CONDITIONS
ARE EXPECTED TUESDAY AND TUESDAY NIGHT.
THERE WILL BE POTENTIAL EPISODES OF SCA CONDITIONS THROUGHOUT THE
WEEK AS A SERIES OF LOWS IMPACT THE WATERS. THE FIRST OF WHICH WILL
SEND A COLD FRONT ACROSS THE AREA WED NIGHT WITH A STRONG WLY FLOW
ON THE BACKSIDE INTO THU MORNING. HIGH PRESSURE THEN BRIEFLY RETURNS
TO THE WATERS ON THU BEFORE LOW PRESSURE PASSES TO THE SOUTH ON FRI.
FOR NOW GOING WITH SUB-SCA CONDITIONS ON FRIDAY WITH THE COASTAL LOW
PASSING TO THE SOUTH...BUT THERE IS MUCH UNCERTAINTY IN THIS
&&
.HYDROLOGY...
TRACE AMOUNTS OF PCPN ARE POSSIBLE TONIGHT.
THERE IS THE POTENTIAL FOR AROUND A 1/4 TO 1/2 AN INCH OF LIQUID
EQUIVALENT TO FALL OVER THE REGION FROM TUESDAY NIGHT INTO WEDNESDAY
NIGHT. SOME OF THIS COULD FALL AS FROZEN PRECIPITATION ACROSS
MAINLY NORTHERN INTERIOR ZONES INTO WEDNESDAY MORNING. NO
SIGNIFICANT HYDROLOGIC IMPACT IS CURRENTLY EXPECTED.
ADDITIONAL PRECIPITATION IS EXPECTED FROM A SERIES OF LOW
PRESSURE SYSTEMS THAT WILL IMPACT THE AREA LATE IN THE WEEK AND
THE WEEKEND. NO SIGNIFICANT HYDROLOGICAL IMPACTS ARE ANTICIPATED
AT THIS TIME.
&&
.OKX WATCHES/WARNINGS/ADVISORIES...
CT...NONE.
NY...NONE.
NJ...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL 1 AM EST TUESDAY FOR ANZ330-335-338-
340-345-355.
GALE WARNING UNTIL 1 AM EST TUESDAY FOR ANZ350-353.
&&
$$
SYNOPSIS...KCS/DW
NEAR TERM...BC/KCS
SHORT TERM...KCS
LONG TERM...DW
AVIATION...24/BS
MARINE...KCS/DW
HYDROLOGY...KCS/DW
AREA FORECAST DISCUSSION
NWS NEW YORK NY
638 AM EST MON DEC 19 2011
.SYNOPSIS...
A HIGH PRESSURE RIDGE SHIFTS OFFSHORE TODAY. A COLD FRONT WILL
MOVE THROUGH TONIGHT. HIGH PRESSURE BUILDS OVER THE AREA TUESDAY. A
WARM FRONT APPROACHES FROM THE SOUTH TUESDAY NIGHT...THEN LIFTS TO
THE NORTH WEDNESDAY...FOLLOWED BY A COLD FRONT WEDNESDAY
NIGHT...AS AN AREA OF LOW PRESSURE PASSES TO OUR NORTH. HIGH
PRESSURE THEN BUILDS IN TO OUR NORTH THURSDAY THROUGH SUNDAY...AS
A COUPLE OF LOW PRESSURE SYSTEMS PASS TO OUR SOUTH FRIDAY AND THEN
LATE NEXT WEEKEND.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
MINOR ADJUSTMENTS MADE TO TEMPS/SKY BASED ON CURRENT OBS EARLY
THIS MORNING. RETURN FLOW IS BEGINNING OVER THE AREA WITH SW WINDS
NOTED ON NYC METRO 11Z OBS. THIS WILL HELP TEMPS MODERATE ACROSS
THE REGION THIS MORNING. FCST GENERALLY ON TRACK.
A HIGH PRESSURE RIDGE LOCATED RIGHT ALONG THE EAST COAST EARLY
THIS MORNING WILL SHIFT OFFSHORE TODAY...ALLOWING RETURN FLOW TO
DEVELOP OVER THE REGION. LOW PRESSURE EMBEDDED IN A STRONG
JETSTREAM ACROSS SOUTHERN CANADA WILL QUICKLY SHIFT EASTWARD
ACROSS QUEBEC...DRAGGING A COLD FRONT ACROSS THE GREAT LAKES
REGION. THE PRESSURE GRADIENT WILL INCREASE QUICKLY TODAY AS THE
LOW PASSES TO OUR NORTH...WITH GUSTY WINDS DEVELOPING BY LATE
MORNING AND CONTINUING THROUGH THE AFTERNOON. 00Z NAM SUGGESTS
LIGHT PRECIP DEVELOPING OVER THE REGION BY LATE AFTERNOON WITH A
WEAK VORT MAX MOVING THROUGH...BUT SIDED WITH 00Z GFS/ECMWF WHICH
KEEP ANY PRECIP NORTH AND WEST OF THE REGION.
WARM AIR ADVECTION DEVELOPS WITH THE HIGH OFFSHORE...ENABLING
TEMPERATURES TO CLIMB INTO THE LOW TO MID 40S AREA WIDE. MAV/MET
GUIDANCE IN GOOD AGREEMENT...AND WERE BLENDED FOR TEMPS.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH TUESDAY NIGHT/...
MODEL CONSENSUS INDICATES COLD FRONT WILL BE LOCATED OVER
WESTERN/NORTHERN NY STATE BY EARLY THIS EVENING...THEN QUICKLY SWEEP
TO THE SOUTHEAST AND MOVE THROUGH THE REGION OVERNIGHT. WITH ZONAL
FLOW ALOFT MOISTURE WILL BE LIMITED...BUT ENOUGH LAKE MOISTURE MAY
ALLOW FOR SOME SPRINKLES AND/OR FLURRIES...WITH POTENTIAL FOR LIGHT
SNOW OVER THE LOWER HUDSON VALLEY. BL TOO WARM FOR FLAKES NEAR THE
COASTS INITIALLY...BUT AS THE CWA GETS INTO THE RR QUAD OF THE H3
150 PLUS KT H3 JET AFT MIDNIGHT...A FEW FLURRIES MAY MIX IN WITH
ANY SPRINKLES HERE AS WELL.
GUSTY WINDS DIMINISH THIS EVENING AS LOW-LEVEL INVERSION
DEVELOPS...BUT GUSTS MAY REDEVELOP BY EARLY TUESDAY MORNING AS
COOLER AIR ALOFT MOVES IN BEHIND THE FRONT.
MAV/MET BLENDED AGAIN FOR LOWS TONIGHT...WHICH WILL RANGE FROM THE
UPPER 20S OVER NORTHERN SECTIONS TO THE MID 30S NEAR THE COASTS.
ON TUESDAY...HIGH PRESSURE RIDGE DROPS FROM THE GREAT LAKES INTO
THE TRI-STATE AREA. WINDS DIMINISH AS THE HIGH BUILDS IN. HIGHS
GENERALLY IN THE LOW TO MID 40S.
&&
.LONG TERM /WEDNESDAY THROUGH SUNDAY/...
A PROGRESSIVE SPLIT FLOW ACROSS THE LOWER 48 GETS A BIT MORE
INTERESTING THIS WEEK AS SEVERAL SOUTHERN BRANCH LOWS INTERACT WITH
MARGINALLY COLD AIR ACROSS THE NE U.S. THE 00Z GFS AND ECMWF ARE IN
REMARKABLE AGREEMENT DURING THIS PERIOD...ALTHOUGH THERE ARE SOME
TIMING DIFFERENCES AS CAN BE EXPECTED. THE GFS IS THE MORE
PROGRESSIVE OF THE SOLUTIONS IN THE HANDLING OF EACH WAVE...WHICH
SEEMS TO MAKE SENSE BASED ON THE PROGRESSIVE NATURE OF THE UPPER
FLOW. AT THIS POINT IN TIME...IT IS TOO EARLY BE SPECIFIC WITH ANY
DETAILS...BUT THERE IS THE POTENTIAL FOR WINTRY WEATHER...
ESPECIALLY ACROSS THE INTERIOR.
THE FIRST STORM SYSTEM WILL EMERGE FROM THE MID MS VALLEY TUE NIGHT
AND TAKE A TRACK TO THE NORTH AND WEST OF THE FORECAST AREA WED.
PCPN AHEAD OF ITS WARM FRONT MAY DEVELOP IN THE OVERNIGHT HOUR TUE.
THE TIMING HERE IS CRITICAL AS THE COLD AIR WILL BE ERODING IN A
STRENGTHENING SOUTHERLY FLOW. COASTAL AREAS WILL BE ALL RAIN...BUT
THERE IS A POSSIBILITY OF A BRIEF WINTRY MIX ACROSS INLAND AREAS
PRIOR TO DAYBREAK. THE STEADIEST PCPN WILL FALL AS RAIN ON WED. THE
TRAILING COLD FRONT WILL THEN BRIEFLY DRY CONDITIONS OUT WED NIGHT
INTO THU. THE NEXT SYSTEM TAKES A TRACK FROM THE LOWER MS VALLEY
THU...NE TO OFF THE MID ATLANTIC COAST ON FRI. THIS SYSTEM TOO MAY
FEATURE A WINTRY MIX INLAND. VERTICAL TEMPERATURE PROFILES ARE
MARGINAL IN BOTH CASES WITH NO REAL GOOD SOURCE OF POLAR AIR. THE
FAST FLOW ACROSS THE NORTHERN TIER OF THE COUNTRY IS PREVENTING A
STRONG SOUTHWARD PUSH.
FINALLY...THE LAST STORM HAS THE POTENTIAL TO IMPACT THE AREA
CHRISTMAS EVE AND DAY. THE ECMWF HAS TRENDED TO A STRONGER LOW IN
COMPARISON TO THE GFS WITH A 989 MB LOW PASSING NEAR CAPE COD NEXT
SUNDAY. THE GFS IS ABOUT 20 MB WEAKER. A DECENT HIGH TO THE NORTH
FOR THIS GO AROUND MAY POSE A MORE SIGNIFICANT WINTER WEATHER
THREAT. ONCE AGAIN THOUGH...THERE WILL LIKELY BE SEVERAL CHANGES IN
THE FORECAST OUT THIS FAR. IT IS DEFINITELY WORTH KEEPING AN EYE ON.
TEMPERATURES WILL START OFF ABOVE NORMAL FOR THE MID WEEK
PERIOD...BUT THEN TRANSITION TO MORE SEASONABLE READINGS FOR THE END
OF THE WEEK INTO NEXT WEEKEND. HIGHS WILL TOP OUT IN THE LOWER 50S
WED AND THU...BUT THEN FALL TO AROUND 40 BY THE WEEKEND.
&&
.AVIATION /12Z MONDAY THROUGH FRIDAY/...
HIGH PRESSURE OVER THE AREA DRIFTS SOUTH AS A COLD FRONT APPROACHES.
THE FRONT MOVES THROUGH THE TERMINALS LATE TONIGHT. COULD BE A FEW
FLURRIES/SPRINKLES ACCOMPANYING THE FROPA...BUT NOT EXPECTED TO
MAKE RUNWAYS WET.
VFR. LIGHT SW WINDS WILL INCREASE AS THE DAY PROGRESSES AS A
RESULT OF A TIGHTENING PRESSURE GRADIENT. GUSTS DEVELOP AFTER 15Z
MONDAY AND PEAK IN THE EARLY TO MID AFTERNOON 20 TO 25 KT. COLD
FROPA BETWEEN 05Z AND 09Z TONIGHT WITH WINDS BECOMING NW.
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)
KJFK FCSTER COMMENTS: GUSTS MAY BEGIN AN HOUR OR SO LATER THAN
FORECAST AND MAY BE A FEW KT HIGHER THAN FORECAST AFT 18Z. OCNL
GUSTS MAY LINGER THROUGH 03Z WHILE DIMINISHING.
KLGA FCSTER COMMENTS: GUSTS MAY BEGIN AN HOUR OR SO LATER THAN
FORECAST AND MAY BE A FEW KT HIGHER THAN FORECAST AFT 18Z. OCNL
GUSTS MAY LINGER THROUGH 03Z WHILE DIMINISHING.
KEWR FCSTER COMMENTS: GUSTS MAY BEGIN AN HOUR OR SO LATER THAN
FORECAST AND MAY BE A FEW KT HIGHER THAN FORECAST AFT 18Z. OCNL
GUSTS MAY LINGER THROUGH 01Z WHILE DIMINISHING.
KTEB FCSTER COMMENTS: GUSTS MAY BEGIN AN HOUR OR SO LATER THAN
FORECAST AND MAY BE A FEW KT HIGHER THAN FORECAST AFT 18Z. OCNL
GUSTS MAY LINGER UNTIL AROUND 00Z WHILE DIMINISHING.
KHPN FCSTER COMMENTS: GUSTS MAY BEGIN AN HOUR OR SO LATER THAN
FORECAST AND MAY BE A FEW KT HIGHER THAN FORECAST AFT 18Z. OCNL
GUSTS MAY LINGER UNTIL AROUND 00Z WHILE DIMINISHING.
KISP FCSTER COMMENTS: GUSTS MAY BEGIN AN HOUR OR SO LATER THAN
FORECAST AND MAY BE A FEW KT HIGHER THAN FORECAST AFT 18Z. OCNL
GUSTS MAY LINGER UNTIL AROUND 00Z WHILE DIMINISHING.
OUTLOOK FOR 12Z TUESDAY THROUGH FRIDAY...
TUE...VFR.
TUE NIGHT AND WED...SUB VFR IN RAIN...A WINTRY MIX POSSIBLE
INLAND TUE NIGHT. BECOMING VFR WED NIGHT.
THU...VFR.
FRI...SUB-VFR POSSIBLE.
&&
.MARINE...
ISSUED GALE WARNING FOR EASTERN TWO OCEAN ZONES BEGINNING LATE
THIS MORNING AS CONFIDENCE INCREASES THAT GALE GUSTS WILL DEVELOP.
WINDS START LIGHT FROM THE SW THIS MORNING...BUT THE PRESSURE
GRADIENT WILL INCREASE QUICKLY AS HIGH PRESSURE MOVES EAST OF THE
WATERS AND A COLD FRONT APPROACHES FROM THE NORTHWEST. SCA
CONTINUES FOR ALL OTHER ZONES. ALSO CAN`T RULE OUT POTENTIAL FOR A
FEW GALE-FORCE GUSTS IN EASTERN LONG ISLAND SOUND AND THE WESTERN
OCEAN WATERS TODAY...AND THESE AREAS WILL NEED TO BE MONITORED.
OTHERWISE SCA CONTINUES OVER ALL WATERS NOT COVERED BY THE GALE
WARNING.
WINDS DIMINISH LATE TONIGHT BEHIND THE COLD FRONT AS HIGH PRESSURE
APPROACHES THE WATERS. SCA-LEVEL SEAS COULD LINGER INTO TUESDAY
ON THE FAR EASTERN COASTAL WATERS...OTHERWISE SUB-SCA CONDITIONS
ARE EXPECTED TUESDAY AND TUESDAY NIGHT.
THERE WILL BE POTENTIAL EPISODES OF SCA CONDITIONS THROUGHOUT THE
WEEK AS A SERIES OF LOWS IMPACT THE WATERS. THE FIRST OF WHICH WILL
SEND A COLD FRONT ACROSS THE AREA WED NIGHT WITH A STRONG WLY FLOW
ON THE BACKSIDE INTO THU MORNING. HIGH PRESSURE THEN BRIEFLY RETURNS
TO THE WATERS ON THU BEFORE LOW PRESSURE PASSES TO THE SOUTH ON FRI.
FOR NOW GOING WITH SUB-SCA CONDITIONS ON FRIDAY WITH THE COASTAL LOW
PASSING TO THE SOUTH...BUT THERE IS MUCH UNCERTAINTY IN THIS
&&
.HYDROLOGY...
TRACE AMOUNTS OF PCPN ARE POSSIBLE TONIGHT.
THERE IS THE POTENTIAL FOR AROUND A 1/4 TO 1/2 AN INCH OF LIQUID
EQUIVALENT TO FALL OVER THE REGION FROM TUESDAY NIGHT INTO WEDNESDAY
NIGHT. SOME OF THIS COULD FALL AS FROZEN PRECIPITATION ACROSS
MAINLY NORTHERN INTERIOR ZONES INTO WEDNESDAY MORNING. NO
SIGNIFICANT HYDROLOGIC IMPACT IS CURRENTLY EXPECTED.
ADDITIONAL PRECIPITATION IS EXPECTED FROM A SERIES OF LOW
PRESSURE SYSTEMS THAT WILL IMPACT THE AREA LATE IN THE WEEK AND
THE WEEKEND. NO SIGNIFICANT HYDROLOGICAL IMPACTS ARE ANTICIPATED
AT THIS TIME.
&&
.OKX WATCHES/WARNINGS/ADVISORIES...
CT...NONE.
NY...NONE.
NJ...NONE.
MARINE...SMALL CRAFT ADVISORY FROM 10 AM THIS MORNING TO 1 AM EST
TUESDAY FOR ANZ330-335-338-340-345-355.
GALE WARNING FROM 10 AM THIS MORNING TO 1 AM EST TUESDAY FOR
ANZ350-353.
&&
$$
SYNOPSIS...KCS/DW
NEAR TERM...KCS
SHORT TERM...KCS
LONG TERM...DW
AVIATION...24
MARINE...KCS/DW
HYDROLOGY...KCS/DW
AREA FORECAST DISCUSSION
NWS NEW YORK NY
558 AM EST MON DEC 19 2011
.SYNOPSIS...
A HIGH PRESSURE RIDGE SHIFTS OFFSHORE TODAY. A COLD FRONT WILL
MOVE THROUGH TONIGHT. HIGH PRESSURE BUILDS OVER THE AREA TUESDAY. A
WARM FRONT APPROACHES FROM THE SOUTH TUESDAY NIGHT...THEN LIFTS TO
THE NORTH WEDNESDAY...FOLLOWED BY A COLD FRONT WEDNESDAY
NIGHT...AS AN AREA OF LOW PRESSURE PASSES TO OUR NORTH. HIGH
PRESSURE THEN BUILDS IN TO OUR NORTH THURSDAY THROUGH SUNDAY...AS
A COUPLE OF LOW PRESSURE SYSTEMS PASS TO OUR SOUTH FRIDAY AND THEN
LATE NEXT WEEKEND.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
MINOR ADJUSTMENTS MADE TO TEMPS/SKY BASED ON CURRENT OBS EARLY
THIS MORNING. RETURN FLOW IS BEGINNING OVER THE AREA WITH SW WINDS
NOTED ON NYC METRO 11Z OBS. THIS WILL HELP TEMPS MODERATE ACROSS
THE REGION THIS MORNING. FCST GENERALLY ON TRACK.
A HIGH PRESSURE RIDGE LOCATED RIGHT ALONG THE EAST COAST EARLY
THIS MORNING WILL SHIFT OFFSHORE TODAY...ALLOWING RETURN FLOW TO
DEVELOP OVER THE REGION. LOW PRESSURE EMBEDDED IN A STRONG
JETSTREAM ACROSS SOUTHERN CANADA WILL QUICKLY SHIFT EASTWARD
ACROSS QUEBEC...DRAGGING A COLD FRONT ACROSS THE GREAT LAKES
REGION. THE PRESSURE GRADIENT WILL INCREASE QUICKLY TODAY AS THE
LOW PASSES TO OUR NORTH...WITH GUSTY WINDS DEVELOPING BY LATE
MORNING AND CONTINUING THROUGH THE AFTERNOON. 00Z NAM SUGGESTS
LIGHT PRECIP DEVELOPING OVER THE REGION BY LATE AFTERNOON WITH A
WEAK VORT MAX MOVING THROUGH...BUT SIDED WITH 00Z GFS/ECMWF WHICH
KEEP ANY PRECIP NORTH AND WEST OF THE REGION.
WARM AIR ADVECTION DEVELOPS WITH THE HIGH OFFSHORE...ENABLING
TEMPERATURES TO CLIMB INTO THE LOW TO MID 40S AREA WIDE. MAV/MET
GUIDANCE IN GOOD AGREEMENT...AND WERE BLENDED FOR TEMPS.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH TUESDAY NIGHT/...
MODEL CONSENSUS INDICATES COLD FRONT WILL BE LOCATED OVER
WESTERN/NORTHERN NY STATE BY EARLY THIS EVENING...THEN QUICKLY SWEEP
TO THE SOUTHEAST AND MOVE THROUGH THE REGION OVERNIGHT. WITH ZONAL
FLOW ALOFT MOISTURE WILL BE LIMITED...BUT ENOUGH LAKE MOISTURE MAY
ALLOW FOR SOME SPRINKLES AND/OR FLURRIES...WITH POTENTIAL FOR LIGHT
SNOW OVER THE LOWER HUDSON VALLEY. BL TOO WARM FOR FLAKES NEAR THE
COASTS INITIALLY...BUT AS THE CWA GETS INTO THE RR QUAD OF THE H3
150 PLUS KT H3 JET AFT MIDNIGHT...A FEW FLURRIES MAY MIX IN WITH
ANY SPRINKLES HERE AS WELL.
GUSTY WINDS DIMINISH THIS EVENING AS LOW-LEVEL INVERSION
DEVELOPS...BUT GUSTS MAY REDEVELOP BY EARLY TUESDAY MORNING AS
COOLER AIR ALOFT MOVES IN BEHIND THE FRONT.
MAV/MET BLENDED AGAIN FOR LOWS TONIGHT...WHICH WILL RANGE FROM THE
UPPER 20S OVER NORTHERN SECTIONS TO THE MID 30S NEAR THE COASTS.
ON TUESDAY...HIGH PRESSURE RIDGE DROPS FROM THE GREAT LAKES INTO
THE TRI-STATE AREA. WINDS DIMINISH AS THE HIGH BUILDS IN. HIGHS
GENERALLY IN THE LOW TO MID 40S.
&&
.LONG TERM /WEDNESDAY THROUGH SUNDAY/...
A PROGRESSIVE SPLIT FLOW ACROSS THE LOWER 48 GETS A BIT MORE
INTERESTING THIS WEEK AS SEVERAL SOUTHERN BRANCH LOWS INTERACT WITH
MARGINALLY COLD AIR ACROSS THE NE U.S. THE 00Z GFS AND ECMWF ARE IN
REMARKABLE AGREEMENT DURING THIS PERIOD...ALTHOUGH THERE ARE SOME
TIMING DIFFERENCES AS CAN BE EXPECTED. THE GFS IS THE MORE
PROGRESSIVE OF THE SOLUTIONS IN THE HANDLING OF EACH WAVE...WHICH
SEEMS TO MAKE SENSE BASED ON THE PROGRESSIVE NATURE OF THE UPPER
FLOW. AT THIS POINT IN TIME...IT IS TOO EARLY BE SPECIFIC WITH ANY
DETAILS...BUT THERE IS THE POTENTIAL FOR WINTRY WEATHER...
ESPECIALLY ACROSS THE INTERIOR.
THE FIRST STORM SYSTEM WILL EMERGE FROM THE MID MS VALLEY TUE NIGHT
AND TAKE A TRACK TO THE NORTH AND WEST OF THE FORECAST AREA WED.
PCPN AHEAD OF ITS WARM FRONT MAY DEVELOP IN THE OVERNIGHT HOUR TUE.
THE TIMING HERE IS CRITICAL AS THE COLD AIR WILL BE ERODING IN A
STRENGTHENING SOUTHERLY FLOW. COASTAL AREAS WILL BE ALL RAIN...BUT
THERE IS A POSSIBILITY OF A BRIEF WINTRY MIX ACROSS INLAND AREAS
PRIOR TO DAYBREAK. THE STEADIEST PCPN WILL FALL AS RAIN ON WED. THE
TRAILING COLD FRONT WILL THEN BRIEFLY DRY CONDITIONS OUT WED NIGHT
INTO THU. THE NEXT SYSTEM TAKES A TRACK FROM THE LOWER MS VALLEY
THU...NE TO OFF THE MID ATLANTIC COAST ON FRI. THIS SYSTEM TOO MAY
FEATURE A WINTRY MIX INLAND. VERTICAL TEMPERATURE PROFILES ARE
MARGINAL IN BOTH CASES WITH NO REAL GOOD SOURCE OF POLAR AIR. THE
FAST FLOW ACROSS THE NORTHERN TIER OF THE COUNTRY IS PREVENTING A
STRONG SOUTHWARD PUSH.
FINALLY...THE LAST STORM HAS THE POTENTIAL TO IMPACT THE AREA
CHRISTMAS EVE AND DAY. THE ECMWF HAS TRENDED TO A STRONGER LOW IN
COMPARISON TO THE GFS WITH A 989 MB LOW PASSING NEAR CAPE COD NEXT
SUNDAY. THE GFS IS ABOUT 20 MB WEAKER. A DECENT HIGH TO THE NORTH
FOR THIS GO AROUND MAY POSE A MORE SIGNIFICANT WINTER WEATHER
THREAT. ONCE AGAIN THOUGH...THERE WILL LIKELY BE SEVERAL CHANGES IN
THE FORECAST OUT THIS FAR. IT IS DEFINITELY WORTH KEEPING AN EYE ON.
TEMPERATURES WILL START OFF ABOVE NORMAL FOR THE MID WEEK
PERIOD...BUT THEN TRANSITION TO MORE SEASONABLE READINGS FOR THE END
OF THE WEEK INTO NEXT WEEKEND. HIGHS WILL TOP OUT IN THE LOWER 50S
WED AND THU...BUT THEN FALL TO AROUND 40 BY THE WEEKEND.
&&
.AVIATION /12Z MONDAY THROUGH FRIDAY/...
HIGH PRESSURE OVER THE AREA DRIFTS SOUTH AS A COLD FRONT APPROACHES.
THE FRONT MOVES THROUGH THE TERMINALS LATE TONIGHT.
VFR. LIGHT AND VARIABLE WINDS EARLY THIS MORNING BECOME SOUTHWEST
AND INCREASE AS THE DAY PROGRESSES WITH A TIGHTENING PRESSURE
GRADIENT. GUSTS DEVELOP AFTER 15Z MONDAY AND PEAK IN THE EARLY TO MID
AFTERNOON 20 TO 25 KT.
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)
KJFK FCSTER COMMENTS: GUSTS MAY BEGIN AN HOUR ON EITHER SIDE OF
15Z AND MAY BE A FEW KT HIGHER THAN FORECAST AFT 18Z. GUSTS MAY
LINGER THROUGH 03Z WHILE DIMINISHING.
KLGA FCSTER COMMENTS: GUSTS MAY BEGIN AN HOUR ON EITHER SIDE OF
15Z AND MAY BE A FEW KT HIGHER THAN FORECAST AFT 18Z. GUSTS MAY
LINGER THROUGH 03Z WHILE DIMINISHING.
KEWR FCSTER COMMENTS: GUSTS MAY BEGIN AN HOUR ON EITHER SIDE OF
15Z AND MAY BE A FEW KT HIGHER THAN FORECAST AFT 18Z. GUSTS MAY
LINGER THROUGH 03Z WHILE DIMINISHING.
KTEB FCSTER COMMENTS: GUSTS MAY BEGIN AN HOUR ON EITHER SIDE OF
15Z AND MAY BE A FEW KT HIGHER THAN FORECAST AFT 18Z. GUSTS MAY
LINGER UNTIL AROUND 00Z WHILE DIMINISHING.
KHPN FCSTER COMMENTS: GUSTS MAY BEGIN AN HOUR ON EITHER SIDE OF
15Z AND MAY BE A FEW KT HIGHER THAN FORECAST AFT 18Z. GUSTS MAY
LINGER UNTIL AROUND 00Z WHILE DIMINISHING.
KISP FCSTER COMMENTS: GUSTS MAY BEGIN AN HOUR ON EITHER SIDE OF
15Z AND MAY BE A FEW KT HIGHER THAN FORECAST AFT 18Z. GUSTS MAY
LINGER UNTIL AROUND 00Z WHILE DIMINISHING.
OUTLOOK FOR 06Z TUESDAY THROUGH FRIDAY...
MON NIGHT...VFR. W WINDS BECMG NW BEHIND A COLD FRONT.
FLURRIES/SPRINKLES POSSIBLE.
TUE...VFR.
TUE NIGHT AND WED...SUB VFR IN RAIN...A WINTRY MIX POSSIBLE
INLAND TUE NIGHT. BECOMING VFR WED NIGHT.
THU...VFR.
FRI...SUB-VFR POSSIBLE.
&&
.MARINE...
ISSUED GALE WARNING FOR EASTERN TWO OCEAN ZONES BEGINNING LATE
THIS MORNING AS CONFIDENCE INCREASES THAT GALE GUSTS WILL DEVELOP.
WINDS START LIGHT FROM THE SW THIS MORNING...BUT THE PRESSURE
GRADIENT WILL INCREASE QUICKLY AS HIGH PRESSURE MOVES EAST OF THE
WATERS AND A COLD FRONT APPROACHES FROM THE NORTHWEST. SCA
CONTINUES FOR ALL OTHER ZONES. ALSO CAN`T RULE OUT POTENTIAL FOR A
FEW GALE-FORCE GUSTS IN EASTERN LONG ISLAND SOUND AND THE WESTERN
OCEAN WATERS TODAY...AND THESE AREAS WILL NEED TO BE MONITORED.
OTHERWISE SCA CONTINUES OVER ALL WATERS NOT COVERED BY THE GALE
WARNING.
WINDS DIMINISH LATE TONIGHT BEHIND THE COLD FRONT AS HIGH PRESSURE
APPROACHES THE WATERS. SCA-LEVEL SEAS COULD LINGER INTO TUESDAY
ON THE FAR EASTERN COASTAL WATERS...OTHERWISE SUB-SCA CONDITIONS
ARE EXPECTED TUESDAY AND TUESDAY NIGHT.
THERE WILL BE POTENTIAL EPISODES OF SCA CONDITIONS THROUGHOUT THE
WEEK AS A SERIES OF LOWS IMPACT THE WATERS. THE FIRST OF WHICH WILL
SEND A COLD FRONT ACROSS THE AREA WED NIGHT WITH A STRONG WLY FLOW
ON THE BACKSIDE INTO THU MORNING. HIGH PRESSURE THEN BRIEFLY RETURNS
TO THE WATERS ON THU BEFORE LOW PRESSURE PASSES TO THE SOUTH ON FRI.
FOR NOW GOING WITH SUB-SCA CONDITIONS ON FRIDAY WITH THE COASTAL LOW
PASSING TO THE SOUTH...BUT THERE IS MUCH UNCERTAINTY IN THIS
&&
.HYDROLOGY...
TRACE AMOUNTS OF PCPN ARE POSSIBLE TONIGHT.
THERE IS THE POTENTIAL FOR AROUND A 1/4 TO 1/2 AN INCH OF LIQUID
EQUIVALENT TO FALL OVER THE REGION FROM TUESDAY NIGHT INTO WEDNESDAY
NIGHT. SOME OF THIS COULD FALL AS FROZEN PRECIPITATION ACROSS
MAINLY NORTHERN INTERIOR ZONES INTO WEDNESDAY MORNING. NO
SIGNIFICANT HYDROLOGIC IMPACT IS CURRENTLY EXPECTED.
ADDITIONAL PRECIPITATION IS EXPECTED FROM A SERIES OF LOW
PRESSURE SYSTEMS THAT WILL IMPACT THE AREA LATE IN THE WEEK AND
THE WEEKEND. NO SIGNIFICANT HYDROLOGICAL IMPACTS ARE ANTICIPATED
AT THIS TIME.
&&
.OKX WATCHES/WARNINGS/ADVISORIES...
CT...NONE.
NY...NONE.
NJ...NONE.
MARINE...SMALL CRAFT ADVISORY FROM 10 AM THIS MORNING TO 1 AM EST
TUESDAY FOR ANZ330-335-338-340-345-355.
GALE WARNING FROM 10 AM THIS MORNING TO 1 AM EST TUESDAY FOR
ANZ350-353.
&&
$$
SYNOPSIS...KCS/DW
NEAR TERM...KCS
SHORT TERM...KCS
LONG TERM...DW
AVIATION...24
MARINE...KCS/DW
HYDROLOGY...KCS/DW
AREA FORECAST DISCUSSION
NWS PITTSBURGH PA
1001 AM EST MON DEC 19 2011
.SYNOPSIS...
A COLD FRONT WILL PUSH INTO THE OHIO VALLEY AND BECOME STATIONARY
MONDAY NIGHT AND TUESDAY...BRINGING A MIXTURE OF RAIN AND SNOW.
LOW PRESSURE MOVING ALONG THIS BOUNDARY WILL BRING RAIN TUESDAY
NIGHT AND WEDNESDAY.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
ONLY MINOR CHANGES TO BRINGS IN SCATTERED POPS A BIT SOONER THIS
MORNING ACROSS OHIO INTO NORTHWEST PA AND BRING CLOUDS TO THE
RIDGES MORE QUICKLY. RAISED MAX TEMPS A COUPLE DEGREES BASED ON
CURRENT READINGS. A FRONTAL BOUNDARY CROSSING THE GREAT LAKES WILL
INCREASE CLOUDS AND RAIN CHANCES THROUGH THE EVENING. SOUTHWEST
FLOW WILL PUSH AFTERNOON TEMPERATURES INTO THE 40S WITH GUSTY
SOUTHWEST WINDS.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH WEDNESDAY/...
LATEST MODEL RUNS CONTINUE TO SHOW SURFACE BOUNDARY BECOMING
STATIONARY ACROSS THE SOUTHERN HALF OF THE FORECAST AREA LATE
TONIGHT. TEMPERATURE PROFILES FROM BUFKIT STILL SUGGEST THAT
MUCH OF THE REGION MAINLY NORTH OF THE MASON-DIXON LINE WILL HAVE
A RAIN/SNOW MIXTURE LATE TONIGHT INTO EARLY TUESDAY MORNING. QPF
AMOUNTS WILL BE LIGHT THROUGH TUESDAY. AREAS NORTH OF PITTSBURGH
TOWARD THE I-80 CORRIDOR WILL LIKELY CHANGE TO ALL SNOW MONDAY
NIGHT BUT ANY ACCUMULATION WILL BE LESS THAN AN INCH.
PRECIPITATION WILL CHANGE TO ALL RAIN BY TUESDAY AFTERNOON AS
TEMPERATURES RISE INTO THE UPPER 30S TO MID 40S.
A SHORT WAVE TROUGH WILL MOVE NORTHEAST FROM THE SOUTHERN PLAINS
WITH ITS ASSOCIATED SURFACE LOW TRACKING ACROSS THE OHIO VALLEY
WEDNESDAY. THIS SYSTEM WILL BRING PERIODS OF RAIN TUESDAY NIGHT
THROUGH LATE WEDNESDAY.
&&
.LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/...
WEAK SURFACE RIDGE WILL GIVE A GENERALLY DRY FORECAST THURSDAY. A
WEAK DISTURBANCE WILL BRING THE CHANCE FOR SHOWERS FRIDAY WITH
ABOVE NORMAL TEMPERATURES FOLLOWED BY HIGH PRESSURE AND SEASONABLE
TEMPERATURES SATURDAY. A COLD FRONT WILL BRING A CHANCE FOR RAIN
OR SNOW SHOWERS CHRISTMAS DAY. OVERALL LONG TERM FORECAST WAS A
MODIFIED VERSION OF THE HPC GRIDS.
&&
.AVIATION /15Z MONDAY THROUGH FRIDAY/...
NOT ALOT TO CHANGE FOR THIS TAF ISSUANCE AS MODEL BUFKIT PROFILES
AND RUC DATA CONTINUE TO SUGGEST WIND SHEAR ALOFT OVERNIGHT.
MAINTAINED WIND SHEAR OF WS010/23040KT THROUGH 16Z AS VERTICAL
MIXING BEGINS TO TAKE PLACE OUT AHEAD OF THE BOUNDARY PROGGED TO
BRING PRECIP TO ALL TERMINALS STARTING AROUND 19Z. SURFACE WINDS
WILL BECOME SOUTHWEST 10-15 KTS WITH GUSTS TO 20-25 KTS BY MIDDAY
MONDAY. CURRENT LAMP AND MAV GUIDANCE SUGGESTS RESTRICTIONS WILL
START OUT AT MVFR AS THE COLD FRONT DROPS SOUTHEASTWARD.
OUTLOOK...MONDAY NIGHT THROUGH FRIDAY...
STALLING COLD FRONTAL PRECIPITATION BAND WILL CAUSE FREQUENT IFR
PERIODS MONDAY NIGHT INTO WEDNESDAY. ENSUING WINTRY MIX MAY CAUSE
ADDED THE AVIATION HAZARD OF LOW LEVEL ICING TUESDAY. COLD POOL
STRATOCUMULUS MAY PROVIDE LINGERING RESTRICTIONS, MAINLY IN THE
MVFR RANGE THURSDAY. A NORTHEAST MOVING LOW PRESSURE SYSTEM MAY
PROVIDE MIXED PRECIPITATION AND IFR RESTRICTIONS FRIDAY.
&&
.PBZ WATCHES/WARNINGS/ADVISORIES...
MD...NONE.
OH...NONE.
PA...NONE.
WV...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS PITTSBURGH PA
714 AM EST MON DEC 19 2011
.SYNOPSIS...
A COLD FRONT WILL PUSH INTO THE OHIO VALLEY AND BECOME STATIONARY
MONDAY NIGHT AND TUESDAY...BRINGING A MIXTURE OF RAIN AND SNOW.
LOW PRESSURE MOVING ALONG THIS BOUNDARY WILL BRING RAIN TUESDAY
NIGHT AND WEDNESDAY.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
ONLY MINOR CHANGES TO NEAR TERM. OVERSPREAD CLOUDS A BIT QUICKER
THIS MORNING AND MADE A FEW TWEAKS TO MORNING TEMPERATURE RISE.
PRECIPITATION PROBABILITIES WILL INCREASE WEST TO EAST BY THIS
AFTERNOON AHEAD OF A FRONTAL BOUNDARY CROSSING THE GREAT LAKES.
SOUTHWEST FLOW WILL PUSH AFTERNOON TEMPERATURES INTO THE 40S.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH WEDNESDAY/...
LATEST MODEL RUNS CONTINUE TO SHOW SURFACE BOUNDARY BECOMING
STATIONARY ACROSS THE SOUTHERN HALF OF THE FORECAST AREA LATE
TONIGHT. TEMPERATURE PROFILES FROM BUFKIT STILL SUGGEST THAT
MUCH OF THE REGION MAINLY NORTH OF THE MASON-DIXON LINE WILL HAVE
A RAIN/SNOW MIXTURE LATE TONIGHT INTO EARLY TUESDAY MORNING. QPF
AMOUNTS WILL BE LIGHT THROUGH TUESDAY. AREAS NORTH OF PITTSBURGH
TOWARD THE I-80 CORRIDOR WILL LIKELY CHANGE TO ALL SNOW MONDAY
NIGHT BUT ANY ACCUMULATION WILL BE LESS THAN AN INCH.
PRECIPITATION WILL CHANGE TO ALL RAIN BY TUESDAY AFTERNOON AS
TEMPERATURES RISE INTO THE UPPER 30S TO MID 40S.
A SHORT WAVE TROUGH WILL MOVE NORTHEAST FROM THE SOUTHERN PLAINS
WITH ITS ASSOCIATED SURFACE LOW TRACKING ACROSS THE OHIO VALLEY
WEDNESDAY. THIS SYSTEM WILL BRING PERIODS OF RAIN TUESDAY NIGHT
THROUGH LATE WEDNESDAY.
&&
.LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/...
WEAK SURFACE RIDGE WILL GIVE A GENERALLY DRY FORECAST THURSDAY. A
WEAK DISTURBANCE WILL BRING THE CHANCE FOR SHOWERS FRIDAY WITH
ABOVE NORMAL TEMPERATURES FOLLOWED BY HIGH PRESSURE AND SEASONABLE
TEMPERATURES SATURDAY. A COLD FRONT WILL BRING A CHANCE FOR RAIN
OR SNOW SHOWERS CHRISTMAS DAY. OVERALL LONG TERM FORECAST WAS A
MODIFIED VERSION OF THE HPC GRIDS.
&&
.AVIATION /12Z MONDAY THROUGH FRIDAY/...
NOT ALOT TO CHANGE FOR THIS TAF ISSUANCE AS MODEL BUFKIT PROFILES
AND RUC DATA CONTINUE TO SUGGEST WIND SHEAR ALOFT OVERNIGHT.
MAINTAINED WIND SHEAR OF WS010/23040KT THROUGH 16Z AS VERTICAL
MIXING BEGINS TO TAKE PLACE OUT AHEAD OF THE BOUNDARY PROGGED TO
BRING PRECIP TO ALL TERMINALS STARTING AROUND 19Z. SURFACE WINDS
WILL BECOME SOUTHWEST 10-15 KTS WITH GUSTS TO 20-25 KTS BY MIDDAY
MONDAY. CURRENT LAMP AND MAV GUIDANCE SUGGESTS RESTRICTIONS WILL
START OUT AT MVFR AS THE COLD FRONT DROPS SOUTHEASTWARD.
OUTLOOK...MONDAY NIGHT THROUGH FRIDAY...
STALLING COLD FRONTAL PRECIPITATION BAND WILL CAUSE FREQUENT IFR
PERIODS MONDAY NIGHT INTO WEDNESDAY. ENSUING WINTRY MIX MAY CAUSE
ADDED THE AVIATION HAZARD OF LOW LEVEL ICING TUESDAY. COLD POOL
STRATOCUMULUS MAY PROVIDE LINGERING RESTRICTIONS, MAINLY IN THE
MVFR RANGE THURSDAY. A NORTHEAST MOVING LOW PRESSURE SYSTEM MAY
PROVIDE MIXED PRECIPITATION AND IFR RESTRICTIONS FRIDAY.
&&
.PBZ WATCHES/WARNINGS/ADVISORIES...
MD...NONE.
OH...NONE.
PA...NONE.
WV...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
735 AM EST MON DEC 19 2011
UPDATED AVIATION DISCUSSION FOR THE 12Z TAFS
.DISCUSSION /TODAY THROUGH SUNDAY/... ISSUED AT 407 AM EST
997MB LOW PRESSURE SYSTEM LOCATED OVER EASTERN ONTARIO WILL CONTINUE
E INTO SRN QUEBEC THIS MORNING. COLD FRONT CURRENTLY SWEEPING
THROUGH CNTRL/ERN UPPER MI...WITH ONLY SCT CLOUDS ASSOCIATED WITH
IT/S PASSING. BEHIND THE FRONT...A LARGE AREA OF LOW CLOUDS OVER NRN
MN...SW ONTARIO AND MANITOBA WOULD INDICATE THAT MOISTURE MAY BE
BETTER THAN INDICATED BY THE 00Z NAM. 00Z GFS AND LATEST RUC RUNS
SEEM TO BE DOING A LITTLE BETTER ON PICKING UP THE LOW CLOUDS AND
WILL FOLLOW THAT FOR THE TODAY FORECAST /WHICH IS A LITTLE MORE
PESSIMISTIC/.
COLD AIR STILL LAGGING BEHIND THE FRONT...AND WITH THE AREA OF LOW
CLOUDS CURRENTLY WORKING INTO WRN UPPER MI...EXPECT SOME PCPN TO
START OVER THE NEXT COUPLE OF HOURS OVER THE UPSLOPE HIGHER TERRAIN.
H850-700 DRY AIR AND SUBSIDENCE WILL HELP KEEP INVERSION HEIGHTS AT
3KFT. DRY NEAR SFC AIR WILL KEEP CLOUD DEPTHS LIMITED /ONLY AROUND
1.5-2KFT/ SO HAVE LIMITED CONF ON MUCH PCPN OCCURRING. THIS COULD
CREATE SOME P-TYPE ISSUES INITIALLY...AS BUFKIT SOUNDINGS SHOW CLOUD
TEMPS ARE ONLY IN THE -4 TO -7C RANGE...LIMITING ICE CRYSTALS.
SHOULD BE A QUICK TRANSITION FROM W TO E THROUGH THE EARLY MORNING
HOURS WITH THE H850 TEMPS FALLING TO -11C BY 15Z. THEREFORE...WILL
CONTINUE MENTION OF DZ/FZDZ THROUGH 12Z OVER THE W AND JUST DZ
THROUGH 15Z OVER THE E DUE TO WARMER SFC TEMPS. THE COLDER H850
TEMPS WILL LIKELY LEAD TO SOME LIGHT LES DEVELOPMENT THIS
MORNING...BUT INVERSION HEIGHTS WILL LIMIT INTENSITY. WITH THE
LONGER FETCH...THINK THE LES WILL CONTINUE THROUGH THE AFTN EVEN
THOUGH THE LOWER INVERSION HEIGHTS MAY END UP LEADING TO MAINLY
CLOUDS. OTHERWISE...TRANSITIONED TO MORE OF A -SHSN/FLURRIES IN THE
AFTN OVER THE W BEFORE DECREASING CLOUDS LATE IN THE AFTN DUE TO THE
WARMING H850 TEMPS AND DRIER AIR FINALLY ARRIVING WITH THE
APPROACHING SFC RIDGE.
HIGH PRESSURE RIDGE SLIDES OVER THE AREA TONIGHT...BRINGING AN END
TO THE LES OVER THE E AND THE LK CLOUDS OVER THE REST OF THE AREA.
WITH THE DECREASING CLOUDS AND WINDS...SHOULD BE A COLD NIGHT OVER
THE INTERIOR LOCATIONS. PWATS AROUND 35 PERCENT OF NORMAL WILL HELP
ENHANCE RADIATIONAL COOLING AND HAVE LOWS IN THE MID SINGLE DIGITS
ABOVE ZERO OVER THE INTERIOR W/CNTRL. WINDS WILL INCREASE SOME OVER
THE FAR W LATE IN THE NIGHT AHEAD OF THE NEXT WAVE...WHICH COULD
LEAD TO A RISE IN TEMPS LATE THERE.
NEXT SHORTWAVE AND ASSOCIATED LOW WILL BE MOVING THROUGH THE NRN
STREAM ON TUES...BUT WITH IT BEING LOCATED MUCH FARTHER N /OVER NRN
ONTARIO AND HUDSON BAY/ EXPECT IT TO HAVE LIMITED AFFECT ON THE
WEATHER OTHER THAN INCREASING THE WSW WINDS. SHOULD BE ANOTHER ABOVE
NORMAL TEMP DAY WITH A MOSTLY SUNNY SKY.
MODELS HAVE CONTINUED THE FASTER TREND WITH MERGING THE SRN STREAM
UPPER LOW CURRENTLY OVER THE SWRN CONUS WITH THE NRN STREAM ON WED
OVER THE LOWER GREAT LKS. WITH THE APPROACHING NRN STREAM WAVE STILL
OVER MANITOBA/SASK...AREA SHOULD BE BETWEEN SYSTEMS AND UNDER WEAK
HIGH PRESSURE TUES NIGHT AND WED MORNING. WILL GO WITH PARTLY CLOUDY
TO MOSTLY CLEAR SKIES FOR NOW...WITH CLOUDS JUST TO THE NW AND SE OF
THE CWA...BUT WILL BE CONTINGENT ON LOW CLOUDS HINTED AT BY THE NAM
NOT STICKING AROUND TOO LONG. THEN WITH SFC TROUGH TO THE
NW...ASSOCIATED WITH LOW OVER HUDSON BAY...NEARING THE CWA IN THE
AFTN AND MOVING THROUGH WED NIGHT...HAVE INCREASED CLOUDS FROM THE
AFTN ON. MOISTURE/FORCING IS WEAK WITH THE PASSAGE OF THE
TROUGH...SO WILL CONTINUE MENTION OF SLIGHTS OVER WRN LK SUPERIOR IN
THE AFTN AND SLIGHTS/LOW CHANCES ALONG THE FRONT WED NIGHT.
UPPER TROUGH THEN SWEEPS ACROSS THE AREA LATE WED NIGHT INTO
FRI...BRINGING A BETTER CHANCE FOR SNOW BEHIND THE FRONT. SOME
DIFFERENCES IN THE H850 TEMPS WITH THE 00Z GFS AND 12Z ECMWF...BUT
OVERALL IDEA IS AROUND -12C...WHICH WOULD CREATE LARGE ENOUGH
DELTA-T VALUES FOR LES. AS IS THE CASE TODAY...H800-650 SUBSIDENCE
AND DRY AIR WILL LIMIT THE INVERSION HEIGHTS TO 4KFT. SHOULD BE
DECENT LLVL MOISTURE TO WORK WITH BELOW THE INVERSION...SO AM
CONFIDENT ENOUGH TO GO WITH CHANCE POPS. WITH THE FORCING BELOW THE
DGZ /CLOUD TOPS ONLY REACH -15C ON THE COLDER GFS/ EXPECT SNOW
RATIOS TO BE IN THE LOW TEENS AND WILL LIKELY ONLY SEE A LIGHT
DUSTING FOR AREAS FAVORED BY A NNW WIND.
UPPER TROUGH STARTS TO SHIFT E ON FRI AS SFC HIGH BEGINS TO PUSH
OVER THE AREA. DRIER AIR ASSOCIATED WITH THE HIGH WILL LEAD TO
DIMINISHING LES POPS THURS NIGHT WEST AND DURING THE DAY FRI
EAST...AS WINDS BECOME ANTICYCLONIC. MAY SEE WEAK UPPER RIDGING ON
SAT...AHEAD OF THE NEXT NRN STREAM TROUGH TO AFFECT THE AREA SAT
NIGHT INTO SUN. ONCE AGAIN...FORCING/MOISTURE LIMITED ALONG THE
FRONT AND THE BEST POTENTIAL FOR PCPN WILL COME ON SUN WITH LES...AS
H850 TEMPS FALL TOWARDS -13C.
&&
.AVIATION /FOR THE 12Z TAF ISSUANCE/...
STRATUS WITH MVFR CIGS HAS SPREAD INTO UPPER MI. GIVEN THE EXTENSIVE
NATURE OF THE STRATUS (EXTENDS WELL NW INTO SE MANITOBA)...THIS FCST
ISSUANCE WILL TREND MUCH MORE PESSIMISTIC BY HOLDING MVFR CIGS
(MOSTLY BLO 2K FT) THRU THE DAY TODAY AT KIWD/KCMX/KSAW. AT SOME
POINT TONIGHT...SKIES WILL CLEAR AS SFC HIGH PRES RIDGE AXIS DROPS
SE THRU THE AREA AND WINDS SHIFT SW.
&&
.MARINE /FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE/...
IN THE WAKE OF A COLD FRONT MOVING SE ACROSS LAKE SUPERIOR...A
PERIOD OF GALE FORCE GUSTS SHOULD OCCUR OVER THE E HALF OF THE LAKE
EARLY THIS MORNING IN ADVANCE OF 5MB/3HR PRES RISES. SINCE CORE OF
PRES RISES WILL SHIFT E OF LAKE SUPERIOR BY MID MORNING...GALE
WARNING WILL MOST LIKELY BE CANCELLED BY NEXT SCHEDULED FCST
ISSUANCE. OTHERWISE...WINDS WILL DIMINISH W TO E TODAY/TONIGHT AS
HIGH PRES QUICKLY APPROACHES AND THEN PASSES ACROSS THE GREAT LAKES.
DEEP LOW PRES MOVING E TO HUDSON BAY EARLY TUE WILL LIKELY BRING
ANOTHER ROUND OF SW GALES TO PORTIONS OF LAKE SUPERIOR...MAINLY THE
W HALF. SW WIND DIRECTION WILL FAVOR THE AREA BTWN THE KEWEENAW AND
ISLE ROYALE FOR STRONGEST WINDS TUE (GUSTS TO AROUND 40KT). GALES
WILL END TUE NIGHT AS PRES GRADIENT WEAKENS. WINDS WILL BE BLO 25KT
WED THRU FRI.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...NONE.
LAKE SUPERIOR...
GALE WARNING UNTIL 1 PM EST THIS AFTERNOON FOR LSZ250-251-266-
267.
GALE WATCH FROM TUESDAY MORNING THROUGH LATE TUESDAY NIGHT FOR
LSZ162-263-264.
GALE WARNING UNTIL 7 AM EST THIS MORNING FOR LSZ264.
LAKE MICHIGAN...NONE.
&&
$$
DISCUSSION...SRF
AVIATION...ROLFSON
MARINE...ROLFSON
AREA FORECAST DISCUSSION...UPDATED
NWS DULUTH MN
542 AM CST MON DEC 19 2011
.AVIATION...12Z TAF ISSUANCE
A LARGE MVFR STRATUS DECK COVERS MANITOBA/ONTARIO/NORTHERN
MN/NORTHWESTERN WI THIS MORNING. MANY MODELS INDICATE THIS LAYER
WILL QUICKLY DISSIPATE THIS MORNING...BUT AM BETTING AGAINST THE
MODELS AND THINK IT WILL BE DIFFICULT FOR THIS STRATUS DECK TO
DISSIPATE. THEREFORE...FORECASTING MVFR CIGS AT ALL TAF SITES
THROUGH AT LEAST THE EARLY AFTERNOON WITH CLEARING BY THIS EVENING.
EXPECT NORTHWEST WINDS AROUND 10 TO 15 KNOTS WHICH WILL RELAX LATE
THIS AFTERNOON AND BECOME VERY LIGHT OVERNIGHT. WIND GUSTS OF 15 TO
25 KNOTS ARE POSSIBLE AT KDLH/KHIB/KINL/KBRD THROUGH MID
MORNING...AND THEN WINDS WILL BECOME LESS GUSTY BY AFTERNOON. LIGHT
SOUTHWEST WINDS WILL BEGIN TO DEVELOP LATE TONIGHT. WIND SHEAR MAY
BE AN ISSUE AT KINL LATE TONIGHT.
&&
.PREV DISCUSSION... /ISSUED 402 AM CST MON DEC 19 2011/
SHORT TERM...TODAY THROUGH TUESDAY...
SURFACE COLD FRONT CONTINUES TO PUSH STEADILY SOUTHWARD THROUGH
WISCONSIN EARLY THIS MORNING IN WAKE OF CLIPPER SYSTEM THAT PASSED
TO OUR NORTH YDAY. THE AIRMASS BEHIND THE COLD FRONT IS NOT
TERRIBLY COLD BY MID DECEMBER STANDARDS FOR THIS PART OF THE WORLD
WITH TEMPS IN THE TEENS TO LOWER 20S..BUT IS ALSO CHARACTERIZED BY
A VERY EXPANSIVE STRATOCUMULUS DECK THAT COVERS ALMOST THE ENTIRE
DULUTH CWA AS OF 330 AM AND EXTENDS SEVERAL HUNDRED MILES TO OUR
NORTH. THE EVOLUTION AND EVENTUAL DISSIPATION OF THIS CLOUD DECK
IS KEY TO THE FORECAST FOR TODAY AND TONIGHT. MOST OF THE SHORT
RANGE MODEL GUIDANCE HAS BEEN INSISTENT FOR MANY MODEL RUNS THAT
THE CLOUDS WILL BREAK UP VERY RAPIDLY THIS MORNING WITH THE HRRR
AND RUC BEING THE OUTLIERS WITH A MUCH MORE SLOW BREAK UP
SOLUTION. GIVEN THE SATELLITE APPEARANCE AND MID DECEMBER
CLIMATOLOGY..WE ARE MUCH LESS OPTIMISTIC THAT CLOUDS WILL BE ABLE
TO BREAK UP AS RAPIDLY AS MUCH OF THE MODEL GUIDANCE SUGGESTS AND
WE HAVE TRENDED TOWARD THE HRRR/RUC SOLUTIONS WHICH CALL FOR
GENERALLY CLOUDY SKIES UNTIL THIS EVENING. NORTHWEST WINDS WILL
CONTINUE TO BE GUSTY THIS MORNING AS 5 MB/3 HR PRESSURE RISE
CENTER CONTINUES TO TRANSLATE ACROSS NRN LAKE SUPERIOR WITH TIGHT
GRADIENT. HOWEVER..WINDS SHUD SLACKEN CONSIDERABLY BY AFTERNOON
WITH LOSS OF ISALLOBARIC COMPONENT AND WEAKENING GRADIENT.
HIGH PRESSURE WILL THEN BUILD INTO THE REGION TONIGHT AND LEAVE
THE AREA LARGELY IN BETWEEN THE BIG SYSTEM COMING OUT ONTO THE
PLAINS TO OUR SOUTH AND THE STRONG WNW FLOW ALOFT ACROSS CANADA.
S/SW FLOW WILL RETURN ON TUESDAY AS RIDGE MOVES TO OUR SOUTH AND
NEXT LOW AMPLITUDE WAVE APPROACHES FROM THE NORTHWEST. THIS
SYSTEM..ON SCHEDULE FOR TUE/TUE NITE..APPEARS TO BE SIMILAR TO
THE ONE THAT JUST PASSED BY WITH A BRIEF SURGE OF WARM AIR
FOLLOWED BY ANOTHER PACIFIC TYPE COLD FRONT TUE NIGHT.
LONG TERM...TUESDAY NIGHT THROUGH SUNDAY...
THE PERIOD SHOULD BEGIN INCREASING CLOUD COVER AS A COLD FRONT IN
MANITOBA AND ONTARIO APPROACHES THE CANADIAN BORDER TUESDAY NIGHT.
THE COLD FRONT WILL LIKELY MOVE THROUGH THE NORTHLAND
WEDNESDAY...RESULTING IN CLOUDY CONDITIONS AND POSSIBLE LIGHT SNOW
ACROSS THE NORTHERN FA. BOTH THE GFS AND ECMWF BRING 850 HPA
TEMPERATURES OF -8 TO -12 CELSIUS OVER WESTERN LAKE SUPERIOR
WEDNESDAY NIGHT AND THURSDAY IN THE WAKE OF THE COLD FRONT.
CONSIDERING THE LAKE SURFACE TEMPERATURE IS AROUND 4 DEGREES
CELSIUS...THAT RESULTS IN SURFACE TO 850 HPA TEMPERATURE DIFFERENCES
AROUND 12 TO 16 DEGREES. THE NORTHERLY WINDS THAT DEVELOP WEDNESDAY
NIGHT AND THURSDAY COULD THEREFORE RESULT IN LAKE EFFECT SNOW ACROSS
THE PARTS OF THE SOUTH SHORE. THE MODELS BRING HIGH PRESSURE INTO
THE UPPER MIDWEST THURSDAY AND FRIDAY...RESULTING IN CLEARING SKIES.
A WARMING TREND LOOKS LIKELY FRIDAY INTO SATURDAY AS SOUTHERLY WINDS
INCREASE AHEAD OF AN APPROACHING COLD FRONT FROM THE WEST. SUNDAY
LOOKS COLDER AND CLOUDY IN THE WAKE OF THE COLD FRONT. THERE MAY BE
SOME LIGHT SNOW.
&&
.POINT TEMPS/POPS...
DLH 23 8 25 16 / 0 0 0 0
INL 21 9 28 18 / 10 0 10 10
BRD 25 10 27 15 / 0 0 0 0
HYR 26 9 25 16 / 0 0 0 0
ASX 28 14 28 20 / 20 0 0 0
&&
.DLH WATCHES/WARNINGS/ADVISORIES...
MN...NONE.
WI...NONE.
LS...SMALL CRAFT ADVISORY UNTIL 3 PM CST THIS AFTERNOON FOR LSZ146-
147.
&&
$$
AVIATION...GROCHOCINSKI
AREA FORECAST DISCUSSION...UPDATED
NWS FORT WORTH TX
931 AM CST MON DEC 19 2011
.AVIATION...
15Z AMEND UPDATE AND CONCERNS...
TIMING OF ANY MULTI-CELLULAR SHRA/TSRA THROUGH MIDDAY WITH FIRST
SHORTWAVE AND LOWERING OF CIGS.
FIRST SHORTWAVE NOW LIFTING NNE WITH LINEAR BAND OF SHRA/EMBEDDED
TSRA LIFTING NNE AROUND 50 KTS BETWEEN ABILENE AND BRECKENRIDGE...WITH
LINE ITSELF MOVING EAST NEAR 25 KTS. THINKING IS SOME STRONG
ELEVATED/MIXED WARMER AIR NEAR I-35 CORRIDOR SHOULD DIMINISH THE
INTENSITY OF THIS BAND BEFORE IT GETS TO D/FW TERMINALS...BUT
ENOUGH TO SPEED UP A VCTS/CB WORDING AT TERMINALS STARTING AT 18Z.
WILL LEAVE TEMPO GROUP FOR MORE STRONG-SEVERE BAND OF TSRA AS IS
FOR NOW WITH TIMING BEING DURING THE MID-LATE AFTERNOON HOURS.
HOWEVER...A FEW MODELS SHOW SLOWER TIMING.
ONLY OTHER ADJUSTMENT IS WITH NEAR 60 KTS SOUTHERLY LLJ MIXING IN
THE NEXT FEW HOURS...HAVE INSERTED SSE SUSTAINED WINDS NEAR 15 KTS
WITH GUSTS AT OR EXCEEDING 25 KTS.
WE WILL CONTINUE TO FINE TUNE TIMING OF CONVECTION AND LOWERING OF
CIGS INTO MVFR/IFR CATEGORY AS WE APPROACH THE ISSUANCE OF THE 18Z
TAFS.
05/
&&
.PREV DISCUSSION... /ISSUED 412 AM CST MON DEC 19 2011/
POWERFUL UPPER LEVEL LOW NEAR EL PASO WILL BEGIN TO CURVE NORTH
AND TRACK ACROSS THE TX PANHANDLE TONIGHT. STORM SYSTEM WILL BE
RESPONSIBLE FOR BLIZZARD CONDITIONS OVER THE SOUTHERN HIGH PLAINS
AND A ROUND OF STORMS WITH A POTENTIAL FOR SEVERE WEATHER HERE.
THIS UPPER LOW IS VERY STRONG AND HAS SIMILARITIES TO THE DEC 29
2006 SYSTEM THAT PRODUCED 22 TORNADOES IN OUR CWA. ALTHOUGH WE DO
NOT EXPECT AN EVENT OF THAT MAGNITUDE THIS TIME DUE TO A FARTHER
NORTH POSITION OF THE WARM FRONT AND LESS UNSTABLE AIR OVER OUR
REGION...IT DOES HEIGHTEN OUR AWARENESS FOR SEVERE WEATHER.
SUBSTANTIAL HEIGHT FALLS ARE ALREADY RESULTING IN 3HR PRESSURE
FALLS OF 3-5 MB ACROSS MUCH OF WEST TX. SOUTHERLY WINDS THROUGH
THE TROPOSPHERE ARE INCREASING...AND WILL CONTINUE TO DO SO DURING
THE DAY. WIND SHEAR WILL BECOME VERY STRONG WITH 0-6KM SHEAR NEAR
60KT AND 0-3KM HELICITY AT OR ABOVE 500 M2/S2. SOUTHERLY 850 MB
WINDS ARE EXPECTED TO REACH 60KT BY NOON...AIDING IN THE TRANSPORT
OF WARM/MOIST AIR INTO THE CWA. RAPID AIR MASS MODIFICATION IS
EXPECTED DURING THE NEXT 12 HOURS...WITH DEWPOINTS LIKELY RISING
INTO THE LOW 60S...WITH SOME MID 60S ACROSS THE SOUTH CENTRAL CWA.
STRONG MOISTURE ADVECTION SHOULD KEEP SKIES CLOUDY...AND HIGH
TEMPS SHOULD BE HELD IN THE MID-UPPER 60S...HELPING TO LIMIT
INSTABILITY. THE PRIMARY INHIBITING FACTOR FOR SEVERE WEATHER AND
THE MOST UNCERTAIN PART OF THIS FORECAST IS THE INSTABILITY. GIVEN
THE NATURE OF THIS DYNAMIC SYSTEM AND ANALOGS TO PAST COOL SEASON
SEVERE WEATHER PRODUCING SYSTEMS...WILL CONTINUE TO FAVOR THE NAM
WHICH IS MOST AGGRESSIVE WITH INSTABILITY. EXPECT SB CAPE TO REACH
1000 J/KG OVER THE SOUTH CENTRAL ZONES...WITH VALUES TAPERING OFF
TO 500 J/KG NEAR THE I-20 CORRIDOR. IT IS IMPORTANT TO NOTE THAT
ABOUT 250 J/KG OF THE TOTAL CAPE RESIDES BELOW 3KM...WHICH IS VERY
HIGH FOR ANYTIME OF THE YEAR...AND INCREASES THE POTENTIAL FOR
VORTEX STRETCHING NEAR THE GROUND AND TORNADOGENESIS.
MOST OF THE STORMS WILL FORM ALONG A NORTH-SOUTH ORIENTED COLD
FRONT THAT WILL REACH THE WESTERN CWA IN THE EARLY AFTERNOON.
AHEAD OF THE FRONT...THERE WILL BE SOME WARM ADVECTION SHOWERS
STREAMING UP FROM THE SOUTH. CONVECTION AHEAD OF THE FRONT MAY BE
DISCRETE...BUT INSTABILITY MAY NOT YET BE HIGH ENOUGH FOR ANYTHING
MORE THAN SHOWERS UNTIL FRONTOGENETIC FORCING ARRIVES WITH THE
FRONT. STORM MOTION IS EXPECTED TO BE AT 45KT AND THIS SUGGESTS
DAMAGING WINDS WILL BE THE PRIMARY SEVERE WEATHER THREAT DUE TO
DOWNWARD MOMENTUM TRANSPORT. BECAUSE STORMS SHOULD FORM INTO A
LINE ALONG THE FRONT...TORNADO POTENTIAL SHOULD BE LIMITED...BUT
CONDITIONS ARE STILL FAVORABLE FOR ISOLATED BRIEF SPIN-UPS WITHIN
THE LINE. SEVERE WEATHER THREAT EXISTS JUST ABOUT EVERYWHERE...BUT
WILL BE HIGHEST ALONG THE I-35 CORRIDOR SOUTH OF I-20 WHERE BAND
OF INSTABILITY WILL BE HIGHEST. THERE IS SOME UNCERTAINTY WITH THE
TIMING...AS THE HRRR IS THE QUICKEST...AND THE NAM ABOUT 5 HOURS
SLOWER. THE ECMWF OFFERS A GOOD COMPROMISE AND EXPECT THE SQUALL
LINE TO IMPACT THE WESTERN ZONES 2-6PM...THE I-35 CORRIDOR
4-8PM...AND MOVE OUT OF THE EASTERN ZONES BY 12AM.
WINDY AND COLDER CONDITIONS ARE EXPECTED TUESDAY AS COLD AIR POURS
IN BEHIND THE CYCLONE. SOME WRAP AROUND CLOUDS WILL AFFECT THE
NORTHERN ZONES. WINDS DIMINISH TUESDAY NIGHT...WITH SUBFREEZING
TEMPS OVER MOST OF THE CWA. NEXT UPPER LEVEL SHORTWAVE WILL
APPROACH WEDNESDAY...WITH INCREASING MID-HIGH CLOUDS. MOISTURE
APPEARS SUFFICIENT FOR A LOW CHANCE OF RAIN OVER THE SOUTHEAST
HALF OF THE AREA WED NIGHT AND THURSDAY MORNING. ONCE THIS IMPULSE
MOVES THROUGH...ANOTHER COLD FRONT WILL ARRIVE THURSDAY EVENING.
EXTENDED FORECAST REMAINS OF VERY LOW CONFIDENCE DUE TO WIDESPREAD
DISAGREEMENT IN HOW SEVERAL VORT LOBES INTERACT WITH EACH OTHER.
REGARDLESS OF THE DETAILS...THE SYNOPTIC PATTERN SUGGESTS WITH
HIGH CONFIDENCE THAT IT WILL BE COLD FOR THE HOLIDAY WEEKEND. WILL
NEED BETTER INTER-MODEL AND RUN-TO-RUN CONSISTENCY BEFORE
ENTERTAINING THE POTENTIAL FOR PRECIPITATION.
TR.92
&&
.PRELIMINARY POINT TEMPS/POPS...
DALLAS-FT. WORTH, TX 63 44 50 31 53 / 100 90 5 0 5
WACO, TX 67 43 53 29 54 / 90 90 5 0 10
PARIS, TX 62 49 56 30 51 / 50 100 10 0 5
DENTON, TX 62 42 47 27 52 / 100 80 10 0 5
MCKINNEY, TX 63 44 49 28 52 / 90 100 10 0 5
DALLAS, TX 64 45 51 33 53 / 90 100 5 0 5
TERRELL, TX 65 47 53 32 52 / 80 100 5 0 5
CORSICANA, TX 68 47 55 33 54 / 70 100 10 0 10
TEMPLE, TX 68 43 55 31 55 / 90 90 5 0 10
MINERAL WELLS, TX 61 39 46 26 53 / 100 40 10 0 5
&&
.FWD WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
05/92
AREA FORECAST DISCUSSION...UPDATED
NWS FORT WORTH TX
528 AM CST MON DEC 19 2011
.AVIATION...
CONCERNS...STRONG TO SEVERE THUNDERSTORMS LATE THIS AFTERNOON.
A STRONG WINTER STORM WILL MOVE OUT OF THE SOUTHERN ROCKIES THIS
MORNING AND MOVE ACROSS KANSAS/OKLAHOMA ON TUESDAY. AS THIS
CYCLONE WINDS UP...MVFR CIGS...SCATTERED SHOWERS AND A FEW
THUNDERSTORMS IN THE WARM SECTOR WILL AFFECT THE TAF SITES
THROUGH MIDDAY. COME LATE THIS AFTERNOON...STRONG TO SEVERE LINEAR
CONVECTION OCCURRING ALONG A COLD FRONT TO THE WEST WILL PUSH
THROUGH THE I-35 CORRIDOR AND ACROSS THE TAF SITES 22-01Z. THE
POTENTIAL EXISTS FOR BRIEF IFR CIGS/VIS DURING THE STRONGER
THUNDERSTORMS. SKIES SHOULD GO VFR AFTER 02Z AS A DRY SLOT MOVES
OVER THE REGION AHEAD OF WRAP-AROUND CLOUDINESS THAT INVADES
NORTH TEXAS ON TUESDAY.
WILL PUSH CIGS DOWN TO MVFR 2500FT EARLY THIS MORNING AND TO
1500FT BY LATE MORNING AS SCATTERED SHOWERS MOVE NORTH AT 50+KTS.
CIGS BECOME VFR QUICKLY THIS EVENING BEHIND THE COLD FRONT.
AIRPORT WEATHER WARNING FOR KDFW IS LIKELY DURING THE AFTERNOON
HOURS FOR LIGHTNING...AND LATE AFTERNOON THROUGH EARLY EVENING
FOR LIGHTNING AND/OR WIND GUSTS 35+KTS. 75
&&
.PREV DISCUSSION... /ISSUED 412 AM CST MON DEC 19 2011/
POWERFUL UPPER LEVEL LOW NEAR EL PASO WILL BEGIN TO CURVE NORTH
AND TRACK ACROSS THE TX PANHANDLE TONIGHT. STORM SYSTEM WILL BE
RESPONSIBLE FOR BLIZZARD CONDITIONS OVER THE SOUTHERN HIGH PLAINS
AND A ROUND OF STORMS WITH A POTENTIAL FOR SEVERE WEATHER HERE.
THIS UPPER LOW IS VERY STRONG AND HAS SIMILARITIES TO THE DEC 29
2006 SYSTEM THAT PRODUCED 22 TORNADOES IN OUR CWA. ALTHOUGH WE DO
NOT EXPECT AN EVENT OF THAT MAGNITUDE THIS TIME DUE TO A FARTHER
NORTH POSITION OF THE WARM FRONT AND LESS UNSTABLE AIR OVER OUR
REGION...IT DOES HEIGHTEN OUR AWARENESS FOR SEVERE WEATHER.
SUBSTANTIAL HEIGHT FALLS ARE ALREADY RESULTING IN 3HR PRESSURE
FALLS OF 3-5 MB ACROSS MUCH OF WEST TX. SOUTHERLY WINDS THROUGH
THE TROPOSPHERE ARE INCREASING...AND WILL CONTINUE TO DO SO DURING
THE DAY. WIND SHEAR WILL BECOME VERY STRONG WITH 0-6KM SHEAR NEAR
60KT AND 0-3KM HELICITY AT OR ABOVE 500 M2/S2. SOUTHERLY 850 MB
WINDS ARE EXPECTED TO REACH 60KT BY NOON...AIDING IN THE TRANSPORT
OF WARM/MOIST AIR INTO THE CWA. RAPID AIR MASS MODIFICATION IS
EXPECTED DURING THE NEXT 12 HOURS...WITH DEWPOINTS LIKELY RISING
INTO THE LOW 60S...WITH SOME MID 60S ACROSS THE SOUTH CENTRAL CWA.
STRONG MOISTURE ADVECTION SHOULD KEEP SKIES CLOUDY...AND HIGH
TEMPS SHOULD BE HELD IN THE MID-UPPER 60S...HELPING TO LIMIT
INSTABILITY. THE PRIMARY INHIBITING FACTOR FOR SEVERE WEATHER AND
THE MOST UNCERTAIN PART OF THIS FORECAST IS THE INSTABILITY. GIVEN
THE NATURE OF THIS DYNAMIC SYSTEM AND ANALOGS TO PAST COOL SEASON
SEVERE WEATHER PRODUCING SYSTEMS...WILL CONTINUE TO FAVOR THE NAM
WHICH IS MOST AGGRESSIVE WITH INSTABILITY. EXPECT SB CAPE TO REACH
1000 J/KG OVER THE SOUTH CENTRAL ZONES...WITH VALUES TAPERING OFF
TO 500 J/KG NEAR THE I-20 CORRIDOR. IT IS IMPORTANT TO NOTE THAT
ABOUT 250 J/KG OF THE TOTAL CAPE RESIDES BELOW 3KM...WHICH IS VERY
HIGH FOR ANYTIME OF THE YEAR...AND INCREASES THE POTENTIAL FOR
VORTEX STRETCHING NEAR THE GROUND AND TORNADOGENESIS.
MOST OF THE STORMS WILL FORM ALONG A NORTH-SOUTH ORIENTED COLD
FRONT THAT WILL REACH THE WESTERN CWA IN THE EARLY AFTERNOON.
AHEAD OF THE FRONT...THERE WILL BE SOME WARM ADVECTION SHOWERS
STREAMING UP FROM THE SOUTH. CONVECTION AHEAD OF THE FRONT MAY BE
DISCRETE...BUT INSTABILITY MAY NOT YET BE HIGH ENOUGH FOR ANYTHING
MORE THAN SHOWERS UNTIL FRONTOGENETIC FORCING ARRIVES WITH THE
FRONT. STORM MOTION IS EXPECTED TO BE AT 45KT AND THIS SUGGESTS
DAMAGING WINDS WILL BE THE PRIMARY SEVERE WEATHER THREAT DUE TO
DOWNWARD MOMENTUM TRANSPORT. BECAUSE STORMS SHOULD FORM INTO A
LINE ALONG THE FRONT...TORNADO POTENTIAL SHOULD BE LIMITED...BUT
CONDITIONS ARE STILL FAVORABLE FOR ISOLATED BRIEF SPIN-UPS WITHIN
THE LINE. SEVERE WEATHER THREAT EXISTS JUST ABOUT EVERYWHERE...BUT
WILL BE HIGHEST ALONG THE I-35 CORRIDOR SOUTH OF I-20 WHERE BAND
OF INSTABILITY WILL BE HIGHEST. THERE IS SOME UNCERTAINTY WITH THE
TIMING...AS THE HRRR IS THE QUICKEST...AND THE NAM ABOUT 5 HOURS
SLOWER. THE ECMWF OFFERS A GOOD COMPROMISE AND EXPECT THE SQUALL
LINE TO IMPACT THE WESTERN ZONES 2-6PM...THE I-35 CORRIDOR
4-8PM...AND MOVE OUT OF THE EASTERN ZONES BY 12AM.
WINDY AND COLDER CONDITIONS ARE EXPECTED TUESDAY AS COLD AIR POURS
IN BEHIND THE CYCLONE. SOME WRAP AROUND CLOUDS WILL AFFECT THE
NORTHERN ZONES. WINDS DIMINISH TUESDAY NIGHT...WITH SUBFREEZING
TEMPS OVER MOST OF THE CWA. NEXT UPPER LEVEL SHORTWAVE WILL
APPROACH WEDNESDAY...WITH INCREASING MID-HIGH CLOUDS. MOISTURE
APPEARS SUFFICIENT FOR A LOW CHANCE OF RAIN OVER THE SOUTHEAST
HALF OF THE AREA WED NIGHT AND THURSDAY MORNING. ONCE THIS IMPULSE
MOVES THROUGH...ANOTHER COLD FRONT WILL ARRIVE THURSDAY EVENING.
EXTENDED FORECAST REMAINS OF VERY LOW CONFIDENCE DUE TO WIDESPREAD
DISAGREEMENT IN HOW SEVERAL VORT LOBES INTERACT WITH EACH OTHER.
REGARDLESS OF THE DETAILS...THE SYNOPTIC PATTERN SUGGESTS WITH
HIGH CONFIDENCE THAT IT WILL BE COLD FOR THE HOLIDAY WEEKEND. WILL
NEED BETTER INTER-MODEL AND RUN-TO-RUN CONSISTENCY BEFORE
ENTERTAINING THE POTENTIAL FOR PRECIPITATION.
TR.92
&&
.PRELIMINARY POINT TEMPS/POPS...
DALLAS-FT. WORTH, TX 63 44 50 31 53 / 100 90 5 0 5
WACO, TX 67 43 53 29 54 / 90 90 5 0 10
PARIS, TX 62 49 56 30 51 / 50 100 10 0 5
DENTON, TX 62 42 47 27 52 / 100 80 10 0 5
MCKINNEY, TX 63 44 49 28 52 / 90 100 10 0 5
DALLAS, TX 64 45 51 33 53 / 90 100 5 0 5
TERRELL, TX 65 47 53 32 52 / 80 100 5 0 5
CORSICANA, TX 68 47 55 33 54 / 70 100 10 0 10
TEMPLE, TX 68 43 55 31 55 / 90 90 5 0 10
MINERAL WELLS, TX 61 39 46 26 53 / 100 40 10 0 5
&&
.FWD WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
75/
AREA FORECAST DISCUSSION
NWS FORT WORTH TX
412 AM CST MON DEC 19 2011
.DISCUSSION...
POWERFUL UPPER LEVEL LOW NEAR EL PASO WILL BEGIN TO CURVE NORTH
AND TRACK ACROSS THE TX PANHANDLE TONIGHT. STORM SYSTEM WILL BE
RESPONSIBLE FOR BLIZZARD CONDITIONS OVER THE SOUTHERN HIGH PLAINS
AND A ROUND OF STORMS WITH A POTENTIAL FOR SEVERE WEATHER HERE.
THIS UPPER LOW IS VERY STRONG AND HAS SIMILARITIES TO THE DEC 29
2006 SYSTEM THAT PRODUCED 22 TORNADOES IN OUR CWA. ALTHOUGH WE DO
NOT EXPECT AN EVENT OF THAT MAGNITUDE THIS TIME DUE TO A FARTHER
NORTH POSITION OF THE WARM FRONT AND LESS UNSTABLE AIR OVER OUR
REGION...IT DOES HEIGHTEN OUR AWARENESS FOR SEVERE WEATHER.
SUBSTANTIAL HEIGHT FALLS ARE ALREADY RESULTING IN 3HR PRESSURE
FALLS OF 3-5 MB ACROSS MUCH OF WEST TX. SOUTHERLY WINDS THROUGH
THE TROPOSPHERE ARE INCREASING...AND WILL CONTINUE TO DO SO DURING
THE DAY. WIND SHEAR WILL BECOME VERY STRONG WITH 0-6KM SHEAR NEAR
60KT AND 0-3KM HELICITY AT OR ABOVE 500 M2/S2. SOUTHERLY 850 MB
WINDS ARE EXPECTED TO REACH 60KT BY NOON...AIDING IN THE TRANSPORT
OF WARM/MOIST AIR INTO THE CWA. RAPID AIR MASS MODIFICATION IS
EXPECTED DURING THE NEXT 12 HOURS...WITH DEWPOINTS LIKELY RISING
INTO THE LOW 60S...WITH SOME MID 60S ACROSS THE SOUTH CENTRAL CWA.
STRONG MOISTURE ADVECTION SHOULD KEEP SKIES CLOUDY...AND HIGH
TEMPS SHOULD BE HELD IN THE MID-UPPER 60S...HELPING TO LIMIT
INSTABILITY. THE PRIMARY INHIBITING FACTOR FOR SEVERE WEATHER AND
THE MOST UNCERTAIN PART OF THIS FORECAST IS THE INSTABILITY. GIVEN
THE NATURE OF THIS DYNAMIC SYSTEM AND ANALOGS TO PAST COOL SEASON
SEVERE WEATHER PRODUCING SYSTEMS...WILL CONTINUE TO FAVOR THE NAM
WHICH IS MOST AGGRESSIVE WITH INSTABILITY. EXPECT SB CAPE TO REACH
1000 J/KG OVER THE SOUTH CENTRAL ZONES...WITH VALUES TAPERING OFF
TO 500 J/KG NEAR THE I-20 CORRIDOR. IT IS IMPORTANT TO NOTE THAT
ABOUT 250 J/KG OF THE TOTAL CAPE RESIDES BELOW 3KM...WHICH IS VERY
HIGH FOR ANYTIME OF THE YEAR...AND INCREASES THE POTENTIAL FOR
VORTEX STRETCHING NEAR THE GROUND AND TORNADOGENESIS.
MOST OF THE STORMS WILL FORM ALONG A NORTH-SOUTH ORIENTED COLD
FRONT THAT WILL REACH THE WESTERN CWA IN THE EARLY AFTERNOON.
AHEAD OF THE FRONT...THERE WILL BE SOME WARM ADVECTION SHOWERS
STREAMING UP FROM THE SOUTH. CONVECTION AHEAD OF THE FRONT MAY BE
DISCRETE...BUT INSTABILITY MAY NOT YET BE HIGH ENOUGH FOR ANYTHING
MORE THAN SHOWERS UNTIL FRONTOGENETIC FORCING ARRIVES WITH THE
FRONT. STORM MOTION IS EXPECTED TO BE AT 45KT AND THIS SUGGESTS
DAMAGING WINDS WILL BE THE PRIMARY SEVERE WEATHER THREAT DUE TO
DOWNWARD MOMENTUM TRANSPORT. BECAUSE STORMS SHOULD FORM INTO A
LINE ALONG THE FRONT...TORNADO POTENTIAL SHOULD BE LIMITED...BUT
CONDITIONS ARE STILL FAVORABLE FOR ISOLATED BRIEF SPIN-UPS WITHIN
THE LINE. SEVERE WEATHER THREAT EXISTS JUST ABOUT EVERYWHERE...BUT
WILL BE HIGHEST ALONG THE I-35 CORRIDOR SOUTH OF I-20 WHERE BAND
OF INSTABILITY WILL BE HIGHEST. THERE IS SOME UNCERTAINTY WITH THE
TIMING...AS THE HRRR IS THE QUICKEST...AND THE NAM ABOUT 5 HOURS
SLOWER. THE ECMWF OFFERS A GOOD COMPROMISE AND EXPECT THE SQUALL
LINE TO IMPACT THE WESTERN ZONES 2-6PM...THE I-35 CORRIDOR
4-8PM...AND MOVE OUT OF THE EASTERN ZONES BY 12AM.
WINDY AND COLDER CONDITIONS ARE EXPECTED TUESDAY AS COLD AIR POURS
IN BEHIND THE CYCLONE. SOME WRAP AROUND CLOUDS WILL AFFECT THE
NORTHERN ZONES. WINDS DIMINISH TUESDAY NIGHT...WITH SUBFREEZING
TEMPS OVER MOST OF THE CWA. NEXT UPPER LEVEL SHORTWAVE WILL
APPROACH WEDNESDAY...WITH INCREASING MID-HIGH CLOUDS. MOISTURE
APPEARS SUFFICIENT FOR A LOW CHANCE OF RAIN OVER THE SOUTHEAST
HALF OF THE AREA WED NIGHT AND THURSDAY MORNING. ONCE THIS IMPULSE
MOVES THROUGH...ANOTHER COLD FRONT WILL ARRIVE THURSDAY EVENING.
EXTENDED FORECAST REMAINS OF VERY LOW CONFIDENCE DUE TO WIDESPREAD
DISAGREEMENT IN HOW SEVERAL VORT LOBES INTERACT WITH EACH OTHER.
REGARDLESS OF THE DETAILS...THE SYNOPTIC PATTERN SUGGESTS WITH
HIGH CONFIDENCE THAT IT WILL BE COLD FOR THE HOLIDAY WEEKEND. WILL
NEED BETTER INTER-MODEL AND RUN-TO-RUN CONSISTENCY BEFORE
ENTERTAINING THE POTENTIAL FOR PRECIPITATION.
TR.92
&&
.PRELIMINARY POINT TEMPS/POPS...
DALLAS-FT. WORTH, TX 63 44 50 31 53 / 100 90 5 0 5
WACO, TX 67 43 53 29 54 / 90 90 5 0 10
PARIS, TX 62 49 56 30 51 / 50 100 10 0 5
DENTON, TX 62 42 47 27 52 / 100 80 10 0 5
MCKINNEY, TX 63 44 49 28 52 / 90 100 10 0 5
DALLAS, TX 64 45 51 33 53 / 90 100 5 0 5
TERRELL, TX 65 47 53 32 52 / 80 100 5 0 5
CORSICANA, TX 68 47 55 33 54 / 70 100 10 0 10
TEMPLE, TX 68 43 55 31 55 / 90 90 5 0 10
MINERAL WELLS, TX 61 39 46 26 53 / 100 40 10 0 5
&&
.FWD WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS CHEYENNE WY
416 AM MST MON DEC 19 2011
.AVIATION...12Z TAFS
STRATUS CONTINUES TO MAKE ITS WAY SOUTH ACROSS THE NORTHERN
NEBRASKA PANHANDLE THIS MORNING. AM SEEING THE BACK EDGE THOUGH ON
STRATUS SATELLITE IMAGERY APPROACHING THE NORTHERN PANHANDLE...SO
KEPT CHADRON MVFR LATEST HRRR FORECAST LOOKS PRETTY GOOD ON TIMING
OF IFR/LIFR ONSET FOR AIRPORTS ALONG AND EAST OF THE LARAMIE RANGE
AND CONTINUE FOLLOWING ITS GUIDANCE. FOR KLAR AND KRWL...BELIEVE
THESE TWO AIRPORTS WILL COME DOWN IN LIGHT SNOW LATER THIS
MORNING. EVENTUALLY...BY MID AFTERNOON...AM EXPECTING STRATUS TO
BREAK UP AS WINDS SHIFT WESTERLY.
CLAYCOMB
&&
.PREV DISCUSSION... /ISSUED 250 AM MST MON DEC 19 2011/
SHORT TERM...TODAY THROUGH WEDNESDAY NIGHT.
TODAY...COLD FRONT QUICKLY PASSED SOUTHWARD ACROSS OUR COUNTIES
EARLIER TONIGHT WITH DECENT COLD AIR ADVECTION ONGOING WITH 2-4 MB 3
HOURLY PRESSURE RISES IN THE WAKE OF THE COLD FRONT. AS INPUT BY DAY
SHIFT FORECAST...WILL MAINTAIN PATCHY FREEZING DRIZZLE ACROSS OUR
PANHANDLE COUNTIES SOUTH OF SCOTTSBLUFF TO ALLIANCE AS THE
ATMOSPHERE SUGGEST FAVORABLE CONDITIONS. LOW AND MID LEVELS WILL
CONTINUE TO SATURATE THIS MORNING AND WITH FAVORABLE NORTHEAST TO
EAST UPSLOPE...AND DYNAMICS FROM PASSING SHORTWAVE TROUGH
ALOFT...WILL INCLUDE 60 TO 100 PERCENT POPS FOR SNOW THIS MORNING
ALONG AND JUST EAST OF THE LARAMIE RANGE WITH LESSER POPS FURTHER
EAST AND WEST DUE TO DRY AIR AT LOW LEVELS AND DOWNSLOPING EAST
WINDS WEST OF THE MOUNTAINS AND SNOW SHADOW EFFECTS. AREAS OF FOG
DEVELOP AS THE TEMPERATURE AND DEWPOINT SPREADS NARROW. SNOWFALL
ACCUMULATIONS LESS THAN 2 INCHES DUE TO PROGRESSIVE NATURE OF THE
SYSTEM AND LIMITED QPF. CHANCES FOR SNOW DECREASE SIGNIFICANTLY THIS
AFTERNOON...THOUGH REMAIN HIGH ACROSS THE SOUTHERN LARAMIE RANGE DUE
TO PERSISTENT EASTERLY UPSLOPE. MUCH COLDER THAN SUNDAY WITH CLOUDS
AND IN THE COLD AIRMASS BEHIND THE FRONT.
TONIGHT...DECREASING CLOUDS AND LIGHT WINDS WILL MAKE FOR A CHILLY
NIGHT WITH COLDEST CONDITIONS ACROSS THE LARAMIE VALLEY. WEAK LEE
TROUGHING DEVELOPS BUT SHOULD NOT HAVE MUCH EFFECT ON LOW
TEMPERATURES.
TUESDAY...SLOW WARMING TREND IN BETWEEN SYSTEMS. WITH SOME SUNSHINE
AND SURFACE LEE TROUGHING INDUCING DOWNSLOPE WARMING...WILL SEE HIGH
TEMPERATURES IN THE 20S WEST AND 30S EAST.
TUESDAY NIGHT...NOT AS COLD AS MONDAY NIGHT AS MID AND HIGH CLOUDS
INCREASE IN ADVANCE OF THE NEXT STRONGER SHORTWAVE TROUGH ALOFT
APPROACHING FROM IDAHO AND WESTERN MONTANA.
WEDNESDAY...RATHER IMPRESSIVE SHORTWAVE TROUGH ALOFT CONTINUES TO
DIG ACROSS IDAHO AND WESTERN WYOMING SENDING ANOTHER COLD FRONT
ACROSS OUR COUNTIES IN THE AFTERNOON. THE NAM SHOWS A DEEPLY
SATURATED LAYER DEVELOPING IN THE AFTERNOON ACROSS OUR COUNTIES IN
THE WAKE OF THE COLD FRONT WHILE THE GFS IS SLOWER IN THE
EVOLVEMENT. NAM TENDS TO DO BETTER IN THESE SITUATIONS AND THUS WILL
FOLLOW ITS SOLUTION BRINGING CHANCE OF SNOW ACROSS ALL OUR COUNTIES
IN THE AFTERNOON...WITH 50 TO 100 PERCENT POPS NORTH OF A RAWLINS TO
CHADRON LINE WITH DEEPLY SATURATED AIRMASS LIFTED BY DYNAMICS AND
OROGRAPHICS.
WEDNESDAY NIGHT...SHORTWAVE TROUGH ALOFT MOVES ACROSS WESTERN
COLORADO WITH DYNAMICS AND OROGRAPHICS PROVIDING THE LIFT OF OUR
SATURATED AIRMASS TO PRODUCE FAIRLY WIDESPREAD LIGHT SNOW OVER OUR
COUNTIES...WITH MOST COVERAGE OVER THE FAVORED UPSLOPE LOCATIONS
NEAR THE SOUTHERN LARAMIE RANGE OF WESTERN LARAMIE COUNTY.
LONG TERM...THURSDAY THROUGH MONDAY
19/00Z ECMWF AND GFS MODEL RUNS IN VERY GOOD AGREEMENT ON TRACK OF
LOW OVER UTAH THURSDAY MORNING POSITIONING OF PRECIPITATION OVER
WYOMING. GFS MORE BULLISH ON QPFS WITH EC MORE CONSERVATIVE. AM
BECOMING A LITTLE CONCERNED THOUGH WITH ACCUMULATING SNOWFALL AS
THIS TRACK IS A FAVORABLE PATTERN FOR US TO SEE SIGNIFICANT
SNOWFALL. LATER SHIFTS WILL NEED TO WATCH TO SEE IF THE LOW SLOWS
DOWN OR SHIFTS SLIGHTLY NORTH OF ITS CURRENT FORECAST TRACK.
LATEST TRACK ON BOTH THE GFS AND ECMWF HAS THE LOW TRACKING FROM
CENTRAL UTAH INTO SOUTHERN COLORADO AND FINALLY INTO NORTHERN NEW
MEXICO THURSDAY AFTERNOON. FOR NOW...HAVE SNOW ACCUMULATIONS OF 3
TO 5 INCHES FROM WEDNESDAY NIGHT THROUGH THURSDAY FOR MUCH OF THE
CWA WITH 10 TO 14 INCHES IN THE SNOWY AND SIERRA MADRE RANGES.
SNOW COMES TO AN END THURSDAY AFTERNOON WITH RIDGING MOVING INTO
THE AREA FROM THE NORTH. WESTERLY WINDS RETURN FRIDAY WITH 700MB
TEMPERATURES INCREASING FROM -14C THURSDAY AFTERNOON TO AROUND -6C
FRIDAY AFTERNOON. TEMPERATURES WILL BE TRICKY FRIDAY AND DEPENDS A
LOT ON RESIDING SNOW FROM THURSDAYS STORM. KEPT TEMPERATURES FAIRLY
COOL WITH LOW 30S FOR HIGHS EAST OF THE LARAMIE RANGE AND LOW 20S WEST.
LOOKS LIKE ANOTHER WEAK SHORTWAVE AND SURFACE COLD FRONT TO TRACK
THROUGH SOUTHEAST WYOMING SATURDAY. 700MB WINDS REALLY INCREASE
WITH THIS SYSTEM WITH GFS FORECASTING WINDS OF 50+KTS FRIDAY
AFTERNOON INTO SATURDAY MORNING. 700MB CRAIG TO CASPER HGT
GRADIENT AROUND 60 METERS AS WELL ON THE GFS DURING THAT TIME. DID
GO AHEAD AND INCREASE WIND SPEEDS FROM THURSDAY NIGHT THROUGH
FRIDAY NIGHT WITH THIS SYSTEM AND LATER SHIFTS WILL NEED TO WATCH
FOR WIND HIGHLIGHTS...ESPECIALLY FOR OUR WIND PRONE AREAS. WILL
ADD HIGH WIND POTENTIAL IN THIS MORNINGS HWO AS WELL.
PRETTY COLD WEEKEND AS 700MB TEMPERATURES FALL BACK DOWN TO -14 TO
-18C. LOOKING PROBABLY AT SINGLE DIGIT LOWS AND HIGHS STRUGGLING
TO GET ABOVE FREEZING. COULD BE COLDER DEPENDING ON ANY EXISTING
SNOW PACK FROM THURSDAYS STORM AS WELL.
&&
FIRE WEATHER...
NO FIRE WEATHER CONCERNS. HIGHER MINIMUM AFTERNOON
RELATIVE HUMIDITIES TODAY IN THE WAKE OF THE COLD FRONT.
&&
.CYS WATCHES/WARNINGS/ADVISORIES...
WY...NONE.
NE...NONE.
&&
$$
SHORT TERM/FIRE WEATHER...RUBIN
LONG TERM/AVIATION...CLAYCOMB
AREA FORECAST DISCUSSION
NWS NEW YORK NY
1256 PM EST MON DEC 19 2011
.SYNOPSIS...
A HIGH PRESSURE RIDGE SHIFTS OFFSHORE TODAY. A COLD FRONT WILL
MOVE THROUGH TONIGHT. HIGH PRESSURE BUILDS OVER THE AREA TUESDAY. A
WARM FRONT APPROACHES FROM THE SOUTH TUESDAY NIGHT...THEN LIFTS TO
THE NORTH WEDNESDAY...FOLLOWED BY A COLD FRONT WEDNESDAY
NIGHT...AS AN AREA OF LOW PRESSURE PASSES TO OUR NORTH. HIGH
PRESSURE THEN BUILDS IN TO OUR NORTH THURSDAY THROUGH SUNDAY...AS
A COUPLE OF LOW PRESSURE SYSTEMS PASS TO OUR SOUTH FRIDAY AND THEN
LATE NEXT WEEKEND.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
A HIGH PRESSURE RIDGE CONTINUES TO SHIFT OFFSHORE TODAY...WITH A
RETURN FLOW OVER THE REGION. LOW PRESSURE EMBEDDED IN A STRONG
JETSTREAM ACROSS SOUTHERN CANADA IS MOVING QUICKLY TO THE EAST
ACROSS QUEBEC...DRAGGING A COLD FRONT ACROSS THE GREAT LAKES
REGION. THE PRESSURE GRADIENT WILL QUICKLY INCREASE THIS AFTERNOON
AS THE LOW PASSES TO OUR NORTH...WITH GUSTY WINDS EXPECTED.
THINKING THAT WE SHOULD JUST SEE SOME CLOUD COVER WITH THE FRONT.
WILL REMOVE ANY MENTION OF ANY PRECIPITATION WITH TOO MUCH DRY AIR
IN PLACE.
WARM AIR ADVECTION DEVELOPS WITH THE HIGH OFFSHORE...ENABLING
TEMPERATURES TO CLIMB INTO THE LOW TO MID 40S AREA WIDE. MAV/MET
GUIDANCE IN GOOD AGREEMENT...AND WERE BLENDED FOR TEMPS.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH TUESDAY NIGHT/...
MODEL CONSENSUS INDICATES COLD FRONT WILL BE LOCATED OVER
WESTERN/NORTHERN NY STATE BY EARLY THIS EVENING...THEN QUICKLY SWEEP
TO THE SOUTHEAST AND MOVE THROUGH THE REGION OVERNIGHT. WITH ZONAL
FLOW ALOFT MOISTURE WILL BE LIMITED...BUT ENOUGH LAKE MOISTURE MAY
ALLOW FOR SOME SPRINKLES AND/OR FLURRIES...WITH POTENTIAL FOR LIGHT
SNOW OVER THE LOWER HUDSON VALLEY. BL TOO WARM FOR FLAKES NEAR THE
COASTS INITIALLY...BUT AS THE CWA GETS INTO THE RR QUAD OF THE H3
150 PLUS KT H3 JET AFT MIDNIGHT...A FEW FLURRIES MAY MIX IN WITH
ANY SPRINKLES HERE AS WELL.
GUSTY WINDS DIMINISH THIS EVENING AS LOW-LEVEL INVERSION
DEVELOPS...BUT GUSTS MAY REDEVELOP BY EARLY TUESDAY MORNING AS
COOLER AIR ALOFT MOVES IN BEHIND THE FRONT.
MAV/MET BLENDED AGAIN FOR LOWS TONIGHT...WHICH WILL RANGE FROM THE
UPPER 20S OVER NORTHERN SECTIONS TO THE MID 30S NEAR THE COASTS.
ON TUESDAY...HIGH PRESSURE RIDGE DROPS FROM THE GREAT LAKES INTO
THE TRI-STATE AREA. WINDS DIMINISH AS THE HIGH BUILDS IN. HIGHS
GENERALLY IN THE LOW TO MID 40S.
&&
.LONG TERM /WEDNESDAY THROUGH SUNDAY/...
A PROGRESSIVE SPLIT FLOW ACROSS THE LOWER 48 GETS A BIT MORE
INTERESTING THIS WEEK AS SEVERAL SOUTHERN BRANCH LOWS INTERACT WITH
MARGINALLY COLD AIR ACROSS THE NE U.S. THE 00Z GFS AND ECMWF ARE IN
REMARKABLE AGREEMENT DURING THIS PERIOD...ALTHOUGH THERE ARE SOME
TIMING DIFFERENCES AS CAN BE EXPECTED. THE GFS IS THE MORE
PROGRESSIVE OF THE SOLUTIONS IN THE HANDLING OF EACH WAVE...WHICH
SEEMS TO MAKE SENSE BASED ON THE PROGRESSIVE NATURE OF THE UPPER
FLOW. AT THIS POINT IN TIME...IT IS TOO EARLY BE SPECIFIC WITH ANY
DETAILS...BUT THERE IS THE POTENTIAL FOR WINTRY WEATHER...
ESPECIALLY ACROSS THE INTERIOR.
THE FIRST STORM SYSTEM WILL EMERGE FROM THE MID MS VALLEY TUE NIGHT
AND TAKE A TRACK TO THE NORTH AND WEST OF THE FORECAST AREA WED.
PCPN AHEAD OF ITS WARM FRONT MAY DEVELOP IN THE OVERNIGHT HOUR TUE.
THE TIMING HERE IS CRITICAL AS THE COLD AIR WILL BE ERODING IN A
STRENGTHENING SOUTHERLY FLOW. COASTAL AREAS WILL BE ALL RAIN...BUT
THERE IS A POSSIBILITY OF A BRIEF WINTRY MIX ACROSS INLAND AREAS
PRIOR TO DAYBREAK. THE STEADIEST PCPN WILL FALL AS RAIN ON WED. THE
TRAILING COLD FRONT WILL THEN BRIEFLY DRY CONDITIONS OUT WED NIGHT
INTO THU. THE NEXT SYSTEM TAKES A TRACK FROM THE LOWER MS VALLEY
THU...NE TO OFF THE MID ATLANTIC COAST ON FRI. THIS SYSTEM TOO MAY
FEATURE A WINTRY MIX INLAND. VERTICAL TEMPERATURE PROFILES ARE
MARGINAL IN BOTH CASES WITH NO REAL GOOD SOURCE OF POLAR AIR. THE
FAST FLOW ACROSS THE NORTHERN TIER OF THE COUNTRY IS PREVENTING A
STRONG SOUTHWARD PUSH.
FINALLY...THE LAST STORM HAS THE POTENTIAL TO IMPACT THE AREA
CHRISTMAS EVE AND DAY. THE ECMWF HAS TRENDED TO A STRONGER LOW IN
COMPARISON TO THE GFS WITH A 989 MB LOW PASSING NEAR CAPE COD NEXT
SUNDAY. THE GFS IS ABOUT 20 MB WEAKER. A DECENT HIGH TO THE NORTH
FOR THIS GO AROUND MAY POSE A MORE SIGNIFICANT WINTER WEATHER
THREAT. ONCE AGAIN THOUGH...THERE WILL LIKELY BE SEVERAL CHANGES IN
THE FORECAST OUT THIS FAR. IT IS DEFINITELY WORTH KEEPING AN EYE ON.
TEMPERATURES WILL START OFF ABOVE NORMAL FOR THE MID WEEK
PERIOD...BUT THEN TRANSITION TO MORE SEASONABLE READINGS FOR THE END
OF THE WEEK INTO NEXT WEEKEND. HIGHS WILL TOP OUT IN THE LOWER 50S
WED AND THU...BUT THEN FALL TO AROUND 40 BY THE WEEKEND.
&&
.AVIATION /18Z MONDAY THROUGH SATURDAY/...
HIGH PRESSURE MOVES EAST WITH INCREASING SW FLOW. A COLD FRONT MOVES
THROUGH THE TERMINALS LATE TONIGHT. COULD BE A FEW
FLURRIES/SPRINKLES ACCOMPANYING THE FROPA...BUT NOT EXPECTED TO
MAKE RUNWAYS WET.
VFR TODAY. INCREASING SW GUSTS TODAY...SPORADIC THROUGH 17Z. LOW
CONFIDENCE AT THIS TIME ON WHEN GUSTS WILL SUBSIDE. COLD FROPA
BETWEEN 05Z AND 09Z TONIGHT WITH WINDS BECOMING NW.
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)
KJFK FCSTER COMMENTS: AMENDMENTS POSSIBLE TO INCREASE GUST
SPEEDS. LOW CONFIDENCE ON TIMING OF GUSTS DIMINISHING...OCNL
GUSTS MAY LINGER THROUGH 03Z WHILE DIMINISHING.
KLGA FCSTER COMMENTS: AMENDMENTS POSSIBLE TO INCREASE GUST
SPEEDS. LOW CONFIDENCE ON TIMING OF GUSTS DIMINISHING...OCNL
GUSTS MAY LINGER THROUGH 03Z WHILE DIMINISHING.
KEWR FCSTER COMMENTS: AMENDMENTS POSSIBLE TO INCREASE GUST
SPEEDS. LOW CONFIDENCE ON TIMING OF GUSTS DIMINISHING...OCNL GUSTS
MAY LINGER THROUGH 03Z WHILE DIMINISHING.
KTEB FCSTER COMMENTS: AMENDMENTS POSSIBLE TO INCREASE GUST
SPEEDS. LOW CONFIDENCE ON TIMING OF GUSTS DIMINISHING...OCNL GUSTS
MAY LINGER THROUGH 03Z WHILE DIMINISHING.
KHPN FCSTER COMMENTS: AMENDMENTS POSSIBLE TO INCREASE GUST
SPEEDS. LOW CONFIDENCE ON TIMING OF GUSTS DIMINISHING...OCNL GUSTS
MAY LINGER THROUGH 03Z WHILE DIMINISHING.
KISP FCSTER COMMENTS: AMENDMENTS POSSIBLE TO INCREASE GUST
SPEEDS. LOW CONFIDENCE ON TIMING OF GUSTS DIMINISHING...OCNL GUSTS
MAY LINGER THROUGH 02Z WHILE DIMINISHING.
OUTLOOK FOR 12Z TUESDAY THROUGH FRIDAY...
TUE...VFR.
TUE NIGHT AND WED...SUB VFR IN RAIN...A WINTRY MIX POSSIBLE
INLAND TUE NIGHT. BECOMING VFR WED NIGHT.
THU...VFR.
FRI...SUB-VFR POSSIBLE.
&&
.MARINE...
GALE WARNING REMAINS UP FOR THE EASTERN TWO OCEAN ZONES. WINDS
EXPECTED TO INCREASE THIS AFTERNOON...AS THE PRESSURE GRADIENT
TIGHTENS THIS AFTERNOON AS HIGH PRESSURE MOVES EAST OF THE WATERS
AND A COLD FRONT APPROACHES FROM THE NORTHWEST. SCA CONTINUES FOR
ALL OTHER ZONES. ALSO CAN`T RULE OUT POTENTIAL FOR A FEW GALE-
FORCE GUSTS IN EASTERN LONG ISLAND SOUND AND THE WESTERN OCEAN
WATERS TODAY...AND THESE AREAS WILL NEED TO BE MONITORED.
OTHERWISE SCA CONTINUES OVER ALL WATERS NOT COVERED BY THE GALE
WARNING.
WINDS DIMINISH LATE TONIGHT BEHIND THE COLD FRONT AS HIGH PRESSURE
APPROACHES THE WATERS. SCA-LEVEL SEAS COULD LINGER INTO TUESDAY
ON THE FAR EASTERN COASTAL WATERS...OTHERWISE SUB-SCA CONDITIONS
ARE EXPECTED TUESDAY AND TUESDAY NIGHT.
THERE WILL BE POTENTIAL EPISODES OF SCA CONDITIONS THROUGHOUT THE
WEEK AS A SERIES OF LOWS IMPACT THE WATERS. THE FIRST OF WHICH WILL
SEND A COLD FRONT ACROSS THE AREA WED NIGHT WITH A STRONG WLY FLOW
ON THE BACKSIDE INTO THU MORNING. HIGH PRESSURE THEN BRIEFLY RETURNS
TO THE WATERS ON THU BEFORE LOW PRESSURE PASSES TO THE SOUTH ON FRI.
FOR NOW GOING WITH SUB-SCA CONDITIONS ON FRIDAY WITH THE COASTAL LOW
PASSING TO THE SOUTH...BUT THERE IS MUCH UNCERTAINTY IN THIS
&&
.HYDROLOGY...
DRY WEATHER EXPECTED THROUGH TUESDAY.
THERE IS THE POTENTIAL FOR AROUND A 1/4 TO 1/2 AN INCH OF LIQUID
EQUIVALENT TO FALL OVER THE REGION FROM TUESDAY NIGHT INTO WEDNESDAY
NIGHT. SOME OF THIS COULD FALL AS FROZEN PRECIPITATION ACROSS
MAINLY NORTHERN INTERIOR ZONES INTO WEDNESDAY MORNING. NO
SIGNIFICANT HYDROLOGIC IMPACT IS CURRENTLY EXPECTED.
ADDITIONAL PRECIPITATION IS EXPECTED FROM A SERIES OF LOW
PRESSURE SYSTEMS THAT WILL IMPACT THE AREA LATE IN THE WEEK AND
THE WEEKEND. NO SIGNIFICANT HYDROLOGICAL IMPACTS ARE ANTICIPATED
AT THIS TIME.
&&
.OKX WATCHES/WARNINGS/ADVISORIES...
CT...NONE.
NY...NONE.
NJ...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL 1 AM EST TUESDAY FOR ANZ330-335-338-
340-345-355.
GALE WARNING UNTIL 1 AM EST TUESDAY FOR ANZ350-353.
&&
$$
SYNOPSIS...KCS/DW
NEAR TERM...BC/KCS
SHORT TERM...KCS
LONG TERM...DW
AVIATION...BS
MARINE...KCS/DW
HYDROLOGY...KCS/DW
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
334 PM CST MON DEC 19 2011
.DISCUSSION...
333 PM CST
THE FORECAST CHALLENGES CENTER ON PRECIPITATION TYPE AND AMOUNTS
WITH THE WEATHER SYSTEM TUESDAY INTO WEDNESDAY...FOLLOWED BY
ANOTHER SYSTEM LATE IN THE WEEK.
/SHORT TERM....TONIGHT THROUGH WEDNESDAY...
SYNOPSIS...THE VIGOROUS WELL-DEFINED UPPER LOW CONTINUES TO
EVOLVE EAST INTO THE TX PANHANDLE THIS AFTERNOON. THE MOISTURE
CANOPY IS EXPANDING NORTH AND SPREADING ACROSS THE
REGION...OVERRIDING LOW-LEVEL COLD AIR ADVECTION BEHIND A FRONT
WHICH WILL STALL NEAR THE I-70 CORRIDOR. THIS FRONT SWUNG WINDS TO
THE NORTH AND DROPPED OUR ANOMALOUSLY WARM MORNING TEMPERATURES
AND HIGH DEW POINTS. THERE WAS EVEN A LAKE BREEZE WITH THE
TEMPERATURE DISCONTINUITY DESPITE THE MONTH BEING DECEMBER. THE
LOWEST TEMPERATURES IN UPSTREAM WI ARE AROUND 30...AND GIVEN THE
EXPANSIVE CLOUD COVER EXPECTED...DO NOT SEE TEMPERATURES TONIGHT
FALLING MUCH BELOW THAT ANYWHERE.
NUMERICAL GUIDANCE PREFERENCE...MODELS CONTINUE WELL CLUSTERED ON
THE SURFACE LOW TRACK WITH THIS SYSTEM. THE 19.12 NAM IS SLIGHTLY
FURTHER NORTH THAN THE GFS...BUT THE GFS IS MORE MOIST WITH THE
WARM AIR RETURN...AND THUS THEY ARE FAIRLY CLOSE WITH THE SUPPORT
FOR PRECIPITATION ON TUESDAY. WRF MODELS AND SREF PROBABILITIES
GENERALLY SUPPORT THEIR OUTPUT. SO HAVE FOLLOWED A BLEND OF THESE
TWO MODELS CLOSELY FOR FORCING...AND THE SLIGHTLY DRIER NAM FOR
FORECAST SOUNDINGS.
PRECIPITATION TONIGHT...THE ELEVATED WARM FRONT...AND THE
NORTHERN PERIPHERY OF MOISTURE TRANSPORT...WILL INCH NORTH INTO
THE SOUTHERN FORECAST AREA THIS EVENING AND SLOWLY NORTH FROM
THERE OVERNIGHT. ISENTROPIC UPGLIDE BECOMES GRADUALLY MORE ROBUST
INTO THE FAR SOUTH. DURING THE EVENING...THE COLUMN IS TOO WARM
FOR ANYTHING BUT RAIN AND AMOUNTS SHOULD GENERALLY BE LIGHT. AS
FOR OVERNIGHT...SLIGHTLY STRONGER QG FORCING MAY COOL THE COLUMN
ENOUGH TO SUPPORT SNOW LOOKING AT NAM/GFS SOUNDINGS AND THICKNESS
REGIMES. THIS WOULD SEEM MOST FAVORED ALONG THE NORTHERN
PERIPHERY OF THE PRECIPITATION SHIELD...WHICH SHOULD BE A TIGHT
GRADIENT GIVEN A STRONG DRY LAYER INDICATED NEAR 800MB ON THE NAM.
ANY SNOW AMOUNTS SHOULD BE LIGHT WITH A LOW RATIO TO WATER
EQUIVALENT.
TUESDAY...THE STRONGEST MOISTURE ADVECTION IS FOCUSED IN THE
SOUTHEAST FORECAST AREA...BUT ELEVATED UPGLIDE WITHIN GENERAL
HEIGHT FALLS WILL EVOLVE NORTH OVER THE AREA. OVER THE PAST THREE
RUNS ON THE NAM AND GFS...THE NORTHERN EXTENT OF PRECIPITATION AT
18Z ON TUESDAY HAS SLOWED DOWN. THIS WAS SOMEWHAT EXPECTED GIVEN
THE DRIER AIR IN THE LOWER LEVELS. NAM SOUNDINGS IN THE NORTHERN
PORTIONS OF THE PRECIPITATION SHIELD WOULD SUPPORT SNOW...WITH
MAXIMUM WET BULBS IN THE COLUMN ONLY AROUND ZERO. IF STRONGER
FRONTOGENETIC FORCING CAN ESTABLISH ITSELF ON THE NORTHERN
EDGE...SNOW AND OR A MIX WOULD BE MORE POSSIBLE. THE NEAR ZERO
LAYER IS PROJECTED TO BE DEEP /3000 TO 4000 FT/ FROM PONTIAC TO
RENSSELAER AT DAYBREAK AND CREEPING NORTHWARD. THIS IS EXPECTED TO
BE WITHIN 2000 FT...AND POSSIBLY ALL THE WAY TO THE SURFACE. SO
SMALL CHANCES FOR SLEET AND FREEZING RAIN STILL EXIST...ESPECIALLY
IN THE LACK OF STRONG FORCING WHICH IS THE CASE DURING THE
MORNING. CONDITIONAL SREF PROBABILITIES FOR FREEZING RAIN ON THE
19.15 SREF REMAIN NEAR 50 PERCENT AT THE NORTHERN EXTENT OF THE
RAIN SHIELD. THE KEY IS THAT THE SREF NOR THE NAM AND GFS ARE
PRODUCING MUCH FOR QPF BUT A FEW HUNDREDTHS. THE LATER THE
PRECIPITATION SPREADS INTO AN AREA DURING TUESDAY MORNING THE
LOWER CHANCE FOR IT TO BE ANYTHING FREEZING...AS THE MORNING
MINIMUM TEMPERATURES SHOULD BOTTOM OUT ONLY NEAR 30 AND THEN INCH
UP DURING THE MORNING. BY AFTERNOON...THE SURFACE TEMPERATURE
ENVELOPE IN THE GUIDANCE LOOKS HIGHLY LIKELY TO BE ABOVE FREEZING
WITH THE COLUMN SUPPORTING RAIN SOUTH OF INTERSTATE 80 AND LIKELY
RAIN WITH A CHANCE FOR A MIX TO THE NORTH. AGAIN...QPF AMOUNTS ARE
STILL GENERALLY LIGHT IN THE CORRIDOR THAT WOULD POTENTIALLY SEE
A MIX.
TUESDAY NIGHT...CONFIDENCE IN THIS PERIOD LOWERS SOME ON POPS AS
THE MAIN MOISTURE RETURN AXIS SHIFTS EAST AND THE UPPER LOW IS
STILL BACK TOWARDS KANSAS CITY AT 00Z. WITH THE AREA BEING NOT FAR
FROM THE NOSE OF THE DRY SLOT...ENOUGH DYNAMIC SUPPORT SHOULD BE
IN PLACE FOR SOME PRECIPITATION...INCLUDING POSSIBLY DRIZZLE...SO
HAVE GONE LIKELY WITH WORDING. TOWARDS THE WI STATE LINE AND
OVERNIGHT IN THE WESTERN FORECAST AREA...THERE WILL CONTINUE TO
BE A CHANCE TO MIX WITH SNOW BASED ON THE GFS SOUNDINGS AND SREF
PROBABILITIES. AGAIN ANY SNOW AMOUNTS SHOULD BE TEMPERED WITH THE
FAIRLY WARM COLUMN. SO OUTSIDE OF THE SOUTH AND EAST WHERE RAIN
AMOUNTS OVER ONE QUARTER OF AN INCH ARE ANTICIPATED...MUCH OF
THIS EVENT THROUGH TUESDAY NIGHT MAY BEST BE CHARACTERIZED BY
BEING A HIGH POP/LOW QPF EVENT.
WEDNESDAY...THE UPPER LOW WILL OPEN UP AS A WAVE AS IT PROGRESSES
OVER THE AREA ..GETTING PICKED UP BY THE NORTHERN STREAM. WITH THE
STRONG VORT...QG FORCING IS PRONOUNCED ACROSS THE AREA. HAVE
INCREASED POPS ACROSS THE EASTERN FORECAST AREA DURING THE MORNING
HOURS...AND THIS MAY NEED TO BE EXPANDED BACK WEST. THE STRONGER
DYNAMICS IF THEY MATERIALIZE WOULD LIKELY FAVOR SNOW OVER RAIN.
SOME MINOR ACCUMULATIONS UNDER AN INCH COULD BE SEEN WITH THAT.
THE COLD AIR ADVECTION IN THE LOW-LEVELS BEHIND THE SYSTEM IS
LIMITED...WITH TEMPERATURES LIKELY ONLY TO DROP SOME UNDER
PRECIPITATION DURING THE MORNING.
/LONG TERM...THURSDAY THROUGH MONDAY...
WHILE DECENT INTRA-MODEL CONSISTENCY EXISTS IN THE DAYS 3-7/HOLIDAY
WEEKEND PERIOD IN THE LARGER SCALE FEATURES (WITH TROFFING IN THE
INTERMOUNTAIN WEST AND RIDGING OVER EASTERN NORTH AMERICA) THERE ARE
HUGE DIFFERENCES IN THE SMALLER SCALE FEATURES THAT WILL DICTATE
THE SENSIBLE WEATHER FOR THE LOCAL AREA. OF PRIMARY CONCERN ARE
CHANCES OF LIGHT SNOW DURING THE FRIDAY INTO SATURDAY PERIOD SHOULD
NORTHERN AND SOUTHERN STREAMS PHASE AND AN INVERTED SFC TROF AND
CLOSED MID-LEVEL LOW SPREAD A SWATH OF LIGHT SNOW ACROSS THE
REGION.
DIFFERENCES IN MODEL SOLUTIONS REMAIN CONSIDERABLE WITH GFS THE MOST
BULLISH WITH THE ABOVE SCENARIO... HOLDING SW UPPER LOW BACK AT
FIRST AND BRINGING IT EASTWARD SLOWLY... ALLOWING ADDITIONAL
MOISTURE TO BE DRAWN NORTH AND EVENTUALLY A SURFACE LOW FORMING IN
RESPONSE TO LOWERING HEIGHTS ALOFT. THE NEW 12Z ECMWF CONTINUES TO
DEPICT BETTER FORCING ALONG A WEAK COLD FRONT THAT SAGS SOUTHEAST
ACROSS THE AREA THURSDAY NIGHT AHEAD OF ANY POSSIBLE UPPER AND THEN
SFC LOW INTERACTION THE GFS ADVERTISES... ALTHOUGH THIS LATEST EC
RUN DOES SHOW SOME SLIGHT TRENDING TOWARD THE 12Z GFS SOLUTION. THE
12Z GEM PUTS FORTH A SIGNIFICANTLY DIFFERENT SCENARIO THAT FANS OF A
WHITE CHRISTMAS WILL NOT LIKE... HOLDING THE SW UPPER LOW BACK OVER
NEW MEXICO EVEN INTO SATURDAY WITH MUCH LESS PHASING OF NORTHERN AND
SOUTHERN STREAMS. AS A RESULT... IT PROGS STRONG SURFACE RIDGING
AND ANTI-CYCLONIC FLOW DEVELOPING INTO NRN IL AND NW IN FRI NIGHT
INTO SAT.
GIVE THE ABOVE THE DAYS 3-7 FORECAST FOR THIS PACKAGE WILL BE A
COMPROMISE. THE WIDE DISPARITY IN THE MEDIUM RANGE MAY NOT BE RESOLVED
UNTIL FEATURES AND PARAMETERS MOVE INTO THE SHORT TERM. THE
RESULTING SLIGHT CHC POPS THURS NIGHT THROUGH SAT AFTERNOON IN THE
FORECAST SHOULD BE INTERPRETED THAT AS OF NOW AT LEAST ONE AND
POSSIBLY A COUPLE OF BRIEF DURATION LIGHT SNOW EVENTS ARE EXPECTED
DURING THE PERIOD. THE BEST ADVICE WE CAN GIVE THOSE TRAVELING OVER
THE BUSY HOLIDAY WEEKEND IS TO CONTINUE TO MONITOR THE FORECAST FOR
UPDATES... AS THE EVENT DRAWS NEARER WE WILL BE BETTER ABLE TO
REFINE EXACTLY WHEN AND WHERE.
MTF/ED F
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 20Z...
* ONGOING FROPA...MVFR CIGS BEHIND THE FRONT
* WIND SHIFT TO WEST THEN NORTHWEST...THEN NORTHEAST
* OCCNL WIND GUSTS THIS AFTERNOON
* PRECIP CHANCES/TYPE TUES MORNING
SHEA
//DISCUSSION...20Z UPDATE...
DID FURTHER TWEAKING TO THE CIG AND WIND FORECAST...EXPECT WINDS
TO CONTINUE TO FLIP AROUND TO THE NORTH AND NORTHEAST OVER THE
COURSE OF THE NEXT FEW HOURS. RUC/NAM AND HRRR GUIDANCE ALL
INDICATE IT OCCURRING IN THE 21-22Z HOUR. MKE AND RAC HAVE ALREADY
FLIPPED FROM 310 TO 350 TO 030 OVER THE COURSE OF A FEW HOURS.
EXPECT TO SEE ENW NEXT...FOLLOWED BY UGN...PWK AND THEN ORD/MDW.
CURRENTLY SEE A RARE DECEMBER LAKE BREEZE ON TORD...AND TIMING
TROUGH ORD/MDW LOOKS TO BE RIGHT IN LINE WITH EARLIER
THINKING...AND AROUND THE 2130 HOUR. OTHERWISE CIG TRENDS DO NOT
LOOK SUPPORTIVE OF LOW END MVFR...AND TRENDED THAT WAY.
SHEA
//DISCUSSION...PREVIOUS 18Z...
VFR CONDITIONS FOR THE TERMINALS WILL BE QUICKLY COMING TO A CLOSE
AS STRATUS SLIDES IN FROM THE NORTH BEHIND A FRONT THAT IS
CURRENTLY SHIFTING THROUGH THE REGION. WINDS AHEAD OF THE FRONT
WILL RANGE FROM 250-280 DEGREES...VEERING TO THE 320 TO 340 RANGE
BEHIND IT. WINDS ARE EXPECTED TO MAINTAIN THE MID TO UPPER TEEN
GUSTS THROUGH THE AFTERNOON AND INTO THE EVENING HOURS. MOST
LOCATIONS WILL SEE THE FRONT SLIDE THROUGH WITHIN THE HOUR...WITH
GYY BEING THE EXCEPTION...JUST ANOTHER HOUR BEYOND. THE MAIN PUSH
OF STRATUS FROM THE NORTH HAD BEEN PRETTY WELL TIMED TO BE AT OR
BEYOND THE 20-21Z HOUR...BUT THE LATEST VISIBLE SATELLITE IMAGERY
IS SHOWING A BIT OF AN ACCELERATION ALONG THE LEADING EDGE. MAY
NEED TO TWEAK THE TIMING OF THE MVFR CIGS SLIGHTLY FOR THE 20Z
AMD. EXPECT CIGS TO FALL INTO THE 015-018 RANGE FOR A FEW HOURS
ONCE IT MOVES THROUGH... BUT INDICATIONS POINT TOWARDS A LEVELING
OFF AND GRADUAL RISE A FEW HOURS BEHIND TO MID AND UPPER LEVEL
MVFR. NOT OVERLY CONFIDENT THAT CIGS WILL FALL TO LOW END MVFR OR
IFR RANGE...BUT THERE IS THE POSSIBILITY THAT COULD HAPPEN FOR A
VERY SHORT TIME. WINDS WILL THEN CONTINUE TO WORK AROUND THE
COMPASS DIAL...GRADUALLY REACHING NORTH...NORTHEAST AND EAST BY
TOMORROW MORNING. THE NEXT CHANCES FOR PRECIP WILL ARRIVE
TOMORROW... AS ANOTHER SYSTEM LIFTS OUT OF THE MISSISSIPPI VALLEY.
THERE ARE STILL SOME UNCERTAIN VARIABLES PERTAINING TO TIMING /AS
TRENDS HAVE BEEN SLOWING/ AS WELL AS P-TYPE.
SHEA
//ORD AND MDW CONFIDENCE...UPDATED 18Z...
* MOD-HIGH CONFIDENCE IN CIG TREND/TIMING FORECAST
** LOW CONFIDENCE ON LOW END MVFR CIG POTENTIAL
* MOD-HIGH CONFIDENCE ON WIND FORECAST
* LOW CONFIDENCE ON PRECIP TYPE/TIMING TUES MORNING
SHEA
//OUTLOOK FOR ORD/MDW FOR 00Z WEDNESDAY-12Z MONDAY...UPDATED 12Z...
TUESDAY NIGHT...RAIN LIKELY. MVFR/IFR CIGS.
WEDNESDAY...CHC OF RAIN AND SNOW. MVFR CIGS BECOMING VFR LATE.
THURSDAY...MAINLY VFR. SCHC OF FLURRIES/MVFR CIGS LATE.
FRIDAY...MVFR WITH A CHC OF SNOW LATE.
SATURDAY...SCHC RAIN OR SNOW THEN SCHC OF SNOW LATE. MVFR/IFR CIGS.
SUNDAY...MVFR CIGS BECOMING VFR.
JEE
&&
.MARINE...
227 PM...A COLD FRONT CONTINUES TO MOVE SOUTHEAST ACROSS THE
SOUTHERN GREAT LAKES REGION THIS AFTERNOON AND IS EXPECTED TO
DISSIPATE AS IT PUSHES SOUTH INTO THE OHIO VALLEY TONIGHT. A LARGE
RIDGE OF HIGH PRESSURE ACROSS THE NORTHERN PLAINS WILL BUILD
ACROSS THE CENTRAL LAKES TONIGHT AND AS IT DOES...THE GRADIENT IS
EXPECTED TO TIGHTEN ACROSS THE SOUTHERN HALF OR SO OF LAKE
MICHIGAN THIS EVENING. NORTHERLY WINDS 20-25KTS WILL TURN
NORTHEAST AND THEN BEGIN TO DIMINISH OVERNIGHT AS THE HIGH
CONTINUES EAST AND THE GRADIENT WEAKENS SOME. LOW PRESSURE
DEVELOPING OVER NORTHERN TEXAS WILL LIFT NORTHEAST TONIGHT AND
TUESDAY REACHING THE SOUTHERN LAKES REGION BY WEDNESDAY
MORNING...AS IT WEAKENS. ANOTHER COLD FRONT IS EXPECTED TO PUSH
SOUTH ACROSS THE LAKES REGION THURSDAY INTO THURSDAY NIGHT. CMS
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...SMALL CRAFT ADVISORY...LMZ740-LMZ741-LMZ742-LMZ743-LMZ744-
LMZ745...6 PM MONDAY TO 10 AM TUESDAY.
&&
$$
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
227 PM CST MON DEC 19 2011
.DISCUSSION...
319 AM CST
THE MAIN FORECAST CONCERNS CENTER AROUND PRECIP TYPE AND COVERAGE
TONIGHT INTO WEDNESDAY AS LOW PRESSURE MOVES NORTHEASTWARD FROM
NORTHERN TEXAS TO NORTHERN OHIO IN CONJUNCTION WITH AN UPPER LOW.
SATELLITE MOISTURE CHANNEL IMAGERY SHOWS SEVERAL KEY FEATURES THAT
WILL DRIVE OUR WEATHER THROUGH MID-WEEK. THE FIRST IS A LOW
AMPLITUDE UPPER LEVEL TROUGH EXTENDING FROM HUDSON BAY SOUTHWESTWARD
AND MOVING TO THE EAST. A SECOND WAVE IN THE UPPER FLOW IS
POSITIONED JUST TO THE SOUTHWEST OF THE FIRST FROM CENTRAL MANITOBA
SOUTHWESTWARD INTO THE NORTHERN U.S. ROCKIES. THE NEXT AND MOST
SIGNIFICANT FEATURE IS THE CUTOFF UPPER LOW SPINNING OVER THE
ARIZONA/NEW MEXICO/MEXICO BORDER WHICH WILL LIFT NORTHEASTWARD AND BRING
US A MIX OF PRECIPITATION TUESDAY AND WEDNESDAY. AT THE
SURFACE...LOW PRESSURE JUST NORTHEAST OF LAKE SUPERIOR ASSOCIATED
WITH THE HUDSON BAY REGION TROUGH CONTINUES TO MOVE EASTWARD WITH A
COLD FRONT EXTENDING SOUTHWESTWARD ACROSS NORTHERN LAKE
HURON...SOUTHERN LAKE MICHIGAN AND BACK INTO NORTHEAST KANSAS.
PRESSURE FALLS ARE ALSO FOUND ACROSS NEW MEXICO AND WEST TEXAS IN
CONJUNCTION WITH THE APPROACHING UPPER LOW.
TODAY AND TONIGHT...MILD AND MOIST SOUTHWESTERLY LOW LEVEL FLOW
CONTINUES ACROSS THE AREA EARLY THIS MORNING AHEAD OF THE
APPROACHING FRONTAL BOUNDARY. TEMPS HAD RISEN SEVERAL DEGREES SINCE
LAST EVENING WITH BREEZY SOUTHWEST WINDS GUSTING TO AROUND 20 KT AND
AN INFLUX OF CLOUD COVER. SPEEDS HAVE STARTED TO SLACKEN SOMEWHAT AS
THE GRADIENT WEAKENS SLIGHTLY AS THE FRONTAL TROUGH APPROACHES SO
TEMPS MAY DROP A FEW DEGREES THROUGH DAYBREAK. THE FRONT WILL CROSS
THE AREA THIS MORNING SHIFTING WINDS TO THE NORTHWEST THEN NORTH.
TEMPS PROBABLY WILL NOT WARM MUCH NORTHWEST WITH MODEST COLD
ADVECTION BUILDING IN BUT SOUTHEASTERN AREAS SHOULD SEE HIGHS A FEW
DEGREES WARMER THAN MORNING TEMPS. MAY SEE TEMPS DROP A FEW DEGREES
DURING THE AFTERNOON IN THE NORTHWEST. LOW CLOUD COVER WILL BE
PERSISTENT THROUGH THE DAY BUT NORTHWEST AREAS WILL LIKELY SEE SOME
BREAKS OF SUNSHINE. FRONTAL FORCING IS WEAK BUT MOISTURE WILL
CONTINUE TO STREAM NORTHEASTWARD ACROSS THE EASTERN HALF OF THE AREA
WITH DECENT HEIGHT FALLS OCCURRING ALOFT. WILL CONTINUE SLIGHT
CHANCE FOR SPRINKLES FAR SOUTH AND EAST.
TONIGHT AND TUESDAY...HIGH PRESSURE WILL SPREAD ACROSS THE NORTHERN PLAINS
AND UPPER MISSISSIPPI RIVER VALLEY INTO THIS EVENING WITH THE
SOUTHERN PERIPHERY PUSHING INTO NORTHERN ILLINOIS. THE COOL FRONT
WILL STALL OUT FROM NORTHERN OHIO SOUTHWEST ACROSS CENTRAL ILLINOIS
AND BACK INTO NORTHEAST OKLAHOMA JOINING UP WITH DEVELOPING LOW
PRESSURE OVER THE TX/OK BORDER. A SHARP MID LEVEL BAROCLINIC ZONE
WILL SET UP FROM NORTHERN OHIO BACK ACROSS CENTRAL ILLINOIS AND
NORTHERN MISSOURI AS THE MANITOBA UPPER TROUGH TRANSLATES ACROSS THE
GREAT LAKES AND BROAD UPPER RIDGING PIVOTS EASTWARD ACROSS THE LOWER
MISSISSIPPI RIVER VALLEY AHEAD OF THE APPROACHING UPPER LOW. HIGH
THETA-E AIR WILL STREAM NORTHWARD INTO THE TEMP GRADIENT RESULTING
IN A BLOSSOMING OF PRECIPITATION ALONG IT STARTING THIS TODAY. WITH
THE HIGH SPREADING ACROSS THE UPPER MS VALLEY INTO THE GREAT LAKES
AND A NORTHEAST LOW LEVEL TRAJECTORY...DRY AIR WILL NEED TO BE
OVERCOME BEFORE PRECIP CAN SPREAD INTO THE SOUTHERN CWA TONIGHT.
EXPECT A SHARP CUTOFF TO THE PRECIP ON ITS NORTHERN FLANK AND AM
THINKING THAT PRECIP WILL ARRIVE ALONG AND SOUTH OF A
PONTIAC-KANKAKEE-RENSSELAER LINE TOWARD 06Z THEN MAKE SLOW NORTHWARD
PROGRESS THROUGH DAYBREAK. EXPECT PRECIP TYPE IN THESE AREAS TO BE
ALL RAIN BUT TYPE BECOMES MORE OF A CHALLENGE TO THE NORTH TUESDAY
MORNING. FORCING LOOKS TO BECOME LESS ORGANIZED TOWARDS INTERSTATE
80 BUT THERE WILL BE A THREAT FOR LIGHT PRECIP STARTING TUESDAY
MORNING. SURFACE TEMPS NORTH OF THE PNT-IKK-RZL LINE WILL PROBABLY
BE AT OR JUST BELOW FREEZING AND COOL SLIGHTLY NORTHWARD TOWARD
I-80. BASED ON FORECAST SOUNDINGS PRECIP WOULD LIKELY START OUT AS
SNOW BUT MAY TRANSITION TO RAIN OR FREEZING RAIN AS THE MID LEVELS
WARM BUT THE COOL/DRY NORTHEASTERLY LOW LEVEL FLOW CONTINUES
UNDERNEATH. LOW LEVEL TEMPS WILL WARM DIURNALLY HOWEVER...AND A
CHANGE OVER TO PRIMARILY RAIN IS EXPECTED TOWARD MIDDAY. LOW PRECIP
CHANCES WILL SPREAD NORTHWARD THE IL/WI BORDER INTO EARLY AFTERNOON
WITH SLIGHTLY WARMING TEMP PROFILES SUPPORTING A RAIN SNOW MIX FROM
ROUGHLY INTERSTATE 88 NORTH.
TUESDAY NIGHT AND WEDNESDAY...THE UPPER LOW WILL BE OVER NORTHEAST
KANSAS WITH THE SURFACE LOW SOMEWHERE OVER SOUTHERN OR SOUTHEAST
MISSOURI. PRETTY GOOD MODEL AGREEMENT ON A DRY PUSH OF AIR LIFTING
NORTHEASTWARD TOWARD LAKE MICHIGAN LATE TUESDAY AFTERNOON AND EARLY
TUESDAY EVENING WHICH SHOULD LIMIT PRECIP CHANCES SOMEWHAT THROUGH
THE EVENING AND POSSIBLY INTO THE EARLY OVERNIGHT. PRECIP TYPE
DURING THIS TIME SHOULD BE RAIN...EXCEPT FAR NORTHWEST WHERE RAIN
AND SNOW MAY MIX. THINGS BECOME MORE CHALLENGING OVERNIGHT AND
WEDNESDAY MORNING AS THE SURFACE LOW PASSES TO THE SOUTHEAST AND THE
UPPER LOW LIFTS NORTHEAST RIGHT ACROSS THE AREA. MID LEVEL FORCING
WILL INCREASE AS DEFORMATION DEVELOPS IN CONJUNCTION WITH Q-VECTOR
CONVERGENCE RESULTING IN ADDITIONAL BANDS OF PRECIP SPREADING IN
FROM THE SOUTHWEST AFTER MIDNIGHT THROUGH MUCH OF WEDNESDAY MORNING.
COLDER AIR WILL WRAP IN...ESPECIALLY ALOFT...LEADING TO A TOUGH
P-TYPE FORECAST. RIGHT NOW EXPECT THAT RAIN WILL MIX WITH AND
POSSIBLY CHANGE TO SNOW INTO WEDNESDAY MORNING ACROSS THE
NORTHWESTERN HALF OF THE AREA OR ROUGHLY WEST OF A CHICAGO TO
PONTIAC LINE...WITH A BETTER CHANCE FOR ALL RAIN TO THE EAST BUT A
MIX MAY OCCUR AS WELL. MODEL AGREEMENT IS SOMEWHAT LACKING IN TERMS
OF THE THERMAL PROFILE SO CONFIDENCE IS LIMITED IN THE DETAILS.
CONCEPTUALLY SPEAKING...AM ALSO CONCERNED THAT IF FORCING CAN BECOME
STRONG THEN DYNAMIC COOLING PROCESSES UNDER THE CORE OF COLDEST AIR
MAY RESULT IN A BAND OF ALL SNOW...WHICH COULD BECOME SOMEWHAT
INTENSE FOR A SHORT TIME. THIS WOULD BE FAST MOVING BUT A STRIPE OF
LOW END ACCUMULATION MAY OCCUR. COLD ADVECTION BEHIND THE DEPARTING
TROUGH IS NOT TERRIBLY STRONG GIVEN THAT WEAK UPPER RIDGING WILL
BUILD IN BEHIND IT SO WE MAY SEE SOME DIURNAL WARMING...ESPECIALLY
IF CLOUDS CAN BREAK UP.
THURSDAY THROUGH MONDAY...WEAK UPPER RIDGING WILL DAMPEN OVER THE
AREA WITH ANOTHER UPPER TROUGH SPREADING ACROSS THE FOUR CORNERS
INTO THE CENTRAL ROCKIES. THE UPPER FLOW LOOKS TO BE AT LEAST
SOMEWHAT SPLIT WITH A TROUGH ACROSS SOUTHERN CANADA. THIS MAY RESULT
IN A TIGHTENING MID LEVEL TEMP GRADIENT FROM SOUTHERN QUEBEC BACK
TOWARDS NEBRASKA THURSDAY WHICH WILL THEN SETTLE SOUTHWARD INTO THE
AREA THURSDAY NIGHT. DOES NOT APPEAR TO BE MUCH FORCING ASSOCIATED
WITH THIS BUT WILL NEED TO WATCH THE NEED FOR LOW PRECIP CHANCES.
THE SOUTHERN STREAM TROUGH WILL TRACK EAST-NORTHEASTWARD ACROSS THE
MID MISSISSIPPI RIVER VALLEY AND PUSH A SURFACE LOW NORTHEASTWARD
SOMEWHERE ACROSS THE OHIO VALLEY SATURDAY. THE ECMWF AND GFS ARE IN
REASONABLE AGREEMENT WITH THE EXISTENCE OF THESE FEATURES BUT DIFFER
ON TRACK WHICH HAS A SIGNIFICANT IMPACT ON OUR SENSIBLE WEATHER. A
WESTERLY TRACK WOULD BRING SNOW TO THE AREA FRIDAY NIGHT AND
SATURDAY. TOO EARLY FOR ANY KIND OF DETAILS BUT MOISTURE CONTENT
DOES NOT LOOK TERRIBLY HIGH SO ACCUMULATION MAY BE MINIMAL SHOULD
PRECIP OCCUR. BEYOND THAT...ANOTHER TROUGH LOOKS TO FOLLOW THE FIRST
BRINGING A PUSH OF NOTICEABLY COLDER AIR IN FOR SUNDAY BUT LARGE
SCALE RIDGING LOOKS TO QUICKLY BRING MILDER AIR BACK TO THE REGION
EARLY NEXT WEEK.
MDB
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 20Z...
* ONGOING FROPA...MVFR CIGS BEHIND THE FRONT
* WIND SHIFT TO WEST THEN NORTHWEST...THEN NORTHEAST
* OCCNL WIND GUSTS THIS AFTERNOON
* PRECIP CHANCES/TYPE TUES MORNING
SHEA
//DISCUSSION...20Z UPDATE...
DID FURTHER TWEAKING TO THE CIG AND WIND FORECAST...EXPECT WINDS
TO CONTINUE TO FLIP AROUND TO THE NORTH AND NORTHEAST OVER THE
COURSE OF THE NEXT FEW HOURS. RUC/NAM AND HRRR GUIDANCE ALL
INDICATE IT OCCURRING IN THE 21-22Z HOUR. MKE AND RAC HAVE ALREADY
FLIPPED FROM 310 TO 350 TO 030 OVER THE COURSE OF A FEW HOURS.
EXPECT TO SEE ENW NEXT...FOLLOWED BY UGN...PWK AND THEN ORD/MDW.
CURRENTLY SEE A RARE DECEMBER LAKE BREEZE ON TORD...AND TIMING
TROUGH ORD/MDW LOOKS TO BE RIGHT IN LINE WITH EARLIER
THINKING...AND AROUND THE 2130 HOUR. OTHERWISE CIG TRENDS DO NOT
LOOK SUPPORTIVE OF LOW END MVFR...AND TRENDED THAT WAY.
SHEA
//DISCUSSION...PREVIOUS 18Z...
VFR CONDITIONS FOR THE TERMINALS WILL BE QUICKLY COMING TO A CLOSE
AS STRATUS SLIDES IN FROM THE NORTH BEHIND A FRONT THAT IS
CURRENTLY SHIFTING THROUGH THE REGION. WINDS AHEAD OF THE FRONT
WILL RANGE FROM 250-280 DEGREES...VEERING TO THE 320 TO 340 RANGE
BEHIND IT. WINDS ARE EXPECTED TO MAINTAIN THE MID TO UPPER TEEN
GUSTS THROUGH THE AFTERNOON AND INTO THE EVENING HOURS. MOST
LOCATIONS WILL SEE THE FRONT SLIDE THROUGH WITHIN THE HOUR...WITH
GYY BEING THE EXCEPTION...JUST ANOTHER HOUR BEYOND. THE MAIN PUSH
OF STRATUS FROM THE NORTH HAD BEEN PRETTY WELL TIMED TO BE AT OR
BEYOND THE 20-21Z HOUR...BUT THE LATEST VISIBLE SATELLITE IMAGERY
IS SHOWING A BIT OF AN ACCELERATION ALONG THE LEADING EDGE. MAY
NEED TO TWEAK THE TIMING OF THE MVFR CIGS SLIGHTLY FOR THE 20Z
AMD. EXPECT CIGS TO FALL INTO THE 015-018 RANGE FOR A FEW HOURS
ONCE IT MOVES THROUGH... BUT INDICATIONS POINT TOWARDS A LEVELING
OFF AND GRADUAL RISE A FEW HOURS BEHIND TO MID AND UPPER LEVEL
MVFR. NOT OVERLY CONFIDENT THAT CIGS WILL FALL TO LOW END MVFR OR
IFR RANGE...BUT THERE IS THE POSSIBILITY THAT COULD HAPPEN FOR A
VERY SHORT TIME. WINDS WILL THEN CONTINUE TO WORK AROUND THE
COMPASS DIAL...GRADUALLY REACHING NORTH...NORTHEAST AND EAST BY
TOMORROW MORNING. THE NEXT CHANCES FOR PRECIP WILL ARRIVE
TOMORROW... AS ANOTHER SYSTEM LIFTS OUT OF THE MISSISSIPPI VALLEY.
THERE ARE STILL SOME UNCERTAIN VARIABLES PERTAINING TO TIMING /AS
TRENDS HAVE BEEN SLOWING/ AS WELL AS P-TYPE.
SHEA
//ORD AND MDW CONFIDENCE...UPDATED 18Z...
* MOD-HIGH CONFIDENCE IN CIG TREND/TIMING FORECAST
** LOW CONFIDENCE ON LOW END MVFR CIG POTENTIAL
* MOD-HIGH CONFIDENCE ON WIND FORECAST
* LOW CONFIDENCE ON PRECIP TYPE/TIMING TUES MORNING
SHEA
//OUTLOOK FOR ORD/MDW FOR 00Z WEDNESDAY-12Z MONDAY...UPDATED 12Z...
TUESDAY NIGHT...RAIN LIKELY. MVFR/IFR CIGS.
WEDNESDAY...CHC OF RAIN AND SNOW. MVFR CIGS BECOMING VFR LATE.
THURSDAY...MAINLY VFR. SCHC OF FLURRIES/MVFR CIGS LATE.
FRIDAY...MVFR WITH A CHC OF SNOW LATE.
SATURDAY...SCHC RAIN OR SNOW THEN SCHC OF SNOW LATE. MVFR/IFR CIGS.
SUNDAY...MVFR CIGS BECOMING VFR.
JEE
&&
.MARINE...
227 PM...A COLD FRONT CONTINUES TO MOVE SOUTHEAST ACROSS THE
SOUTHERN GREAT LAKES REGION THIS AFTERNOON AND IS EXPECTED TO
DISSIPATE AS IT PUSHES SOUTH INTO THE OHIO VALLEY TONIGHT. A LARGE
RIDGE OF HIGH PRESSURE ACROSS THE NORTHERN PLAINS WILL BUILD
ACROSS THE CENTRAL LAKES TONIGHT AND AS IT DOES...THE GRADIENT IS
EXPECTED TO TIGHTEN ACROSS THE SOUTHERN HALF OR SO OF LAKE
MICHIGAN THIS EVENING. NORTHERLY WINDS 20-25KTS WILL TURN
NORTHEAST AND THEN BEGIN TO DIMINISH OVERNIGHT AS THE HIGH
CONTINUES EAST AND THE GRADIENT WEAKENS SOME. LOW PRESSURE
DEVELOPING OVER NORTHERN TEXAS WILL LIFT NORTHEAST TONIGHT AND
TUESDAY REACHING THE SOUTHERN LAKES REGION BY WEDNESDAY
MORNING...AS IT WEAKENS. ANOTHER COLD FRONT IS EXPECTED TO PUSH
SOUTH ACROSS THE LAKES REGION THURSDAY INTO THURSDAY NIGHT. CMS
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...SMALL CRAFT ADVISORY...LMZ740-LMZ741-LMZ742-LMZ743-LMZ744-
LMZ745...6 PM MONDAY TO 10 AM TUESDAY.
&&
$$
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
207 PM CST MON DEC 19 2011
.DISCUSSION...
319 AM CST
THE MAIN FORECAST CONCERNS CENTER AROUND PRECIP TYPE AND COVERAGE
TONIGHT INTO WEDNESDAY AS LOW PRESSURE MOVES NORTHEASTWARD FROM
NORTHERN TEXAS TO NORTHERN OHIO IN CONJUNCTION WITH AN UPPER LOW.
SATELLITE MOISTURE CHANNEL IMAGERY SHOWS SEVERAL KEY FEATURES THAT
WILL DRIVE OUR WEATHER THROUGH MID-WEEK. THE FIRST IS A LOW
AMPLITUDE UPPER LEVEL TROUGH EXTENDING FROM HUDSON BAY SOUTHWESTWARD
AND MOVING TO THE EAST. A SECOND WAVE IN THE UPPER FLOW IS
POSITIONED JUST TO THE SOUTHWEST OF THE FIRST FROM CENTRAL MANITOBA
SOUTHWESTWARD INTO THE NORTHERN U.S. ROCKIES. THE NEXT AND MOST
SIGNIFICANT FEATURE IS THE CUTOFF UPPER LOW SPINNING OVER THE
ARIZONA/NEW MEXICO/MEXICO BORDER WHICH WILL LIFT NORTHEASTWARD AND BRING
US A MIX OF PRECIPITATION TUESDAY AND WEDNESDAY. AT THE
SURFACE...LOW PRESSURE JUST NORTHEAST OF LAKE SUPERIOR ASSOCIATED
WITH THE HUDSON BAY REGION TROUGH CONTINUES TO MOVE EASTWARD WITH A
COLD FRONT EXTENDING SOUTHWESTWARD ACROSS NORTHERN LAKE
HURON...SOUTHERN LAKE MICHIGAN AND BACK INTO NORTHEAST KANSAS.
PRESSURE FALLS ARE ALSO FOUND ACROSS NEW MEXICO AND WEST TEXAS IN
CONJUNCTION WITH THE APPROACHING UPPER LOW.
TODAY AND TONIGHT...MILD AND MOIST SOUTHWESTERLY LOW LEVEL FLOW
CONTINUES ACROSS THE AREA EARLY THIS MORNING AHEAD OF THE
APPROACHING FRONTAL BOUNDARY. TEMPS HAD RISEN SEVERAL DEGREES SINCE
LAST EVENING WITH BREEZY SOUTHWEST WINDS GUSTING TO AROUND 20 KT AND
AN INFLUX OF CLOUD COVER. SPEEDS HAVE STARTED TO SLACKEN SOMEWHAT AS
THE GRADIENT WEAKENS SLIGHTLY AS THE FRONTAL TROUGH APPROACHES SO
TEMPS MAY DROP A FEW DEGREES THROUGH DAYBREAK. THE FRONT WILL CROSS
THE AREA THIS MORNING SHIFTING WINDS TO THE NORTHWEST THEN NORTH.
TEMPS PROBABLY WILL NOT WARM MUCH NORTHWEST WITH MODEST COLD
ADVECTION BUILDING IN BUT SOUTHEASTERN AREAS SHOULD SEE HIGHS A FEW
DEGREES WARMER THAN MORNING TEMPS. MAY SEE TEMPS DROP A FEW DEGREES
DURING THE AFTERNOON IN THE NORTHWEST. LOW CLOUD COVER WILL BE
PERSISTENT THROUGH THE DAY BUT NORTHWEST AREAS WILL LIKELY SEE SOME
BREAKS OF SUNSHINE. FRONTAL FORCING IS WEAK BUT MOISTURE WILL
CONTINUE TO STREAM NORTHEASTWARD ACROSS THE EASTERN HALF OF THE AREA
WITH DECENT HEIGHT FALLS OCCURRING ALOFT. WILL CONTINUE SLIGHT
CHANCE FOR SPRINKLES FAR SOUTH AND EAST.
TONIGHT AND TUESDAY...HIGH PRESSURE WILL SPREAD ACROSS THE NORTHERN PLAINS
AND UPPER MISSISSIPPI RIVER VALLEY INTO THIS EVENING WITH THE
SOUTHERN PERIPHERY PUSHING INTO NORTHERN ILLINOIS. THE COOL FRONT
WILL STALL OUT FROM NORTHERN OHIO SOUTHWEST ACROSS CENTRAL ILLINOIS
AND BACK INTO NORTHEAST OKLAHOMA JOINING UP WITH DEVELOPING LOW
PRESSURE OVER THE TX/OK BORDER. A SHARP MID LEVEL BAROCLINIC ZONE
WILL SET UP FROM NORTHERN OHIO BACK ACROSS CENTRAL ILLINOIS AND
NORTHERN MISSOURI AS THE MANITOBA UPPER TROUGH TRANSLATES ACROSS THE
GREAT LAKES AND BROAD UPPER RIDGING PIVOTS EASTWARD ACROSS THE LOWER
MISSISSIPPI RIVER VALLEY AHEAD OF THE APPROACHING UPPER LOW. HIGH
THETA-E AIR WILL STREAM NORTHWARD INTO THE TEMP GRADIENT RESULTING
IN A BLOSSOMING OF PRECIPITATION ALONG IT STARTING THIS TODAY. WITH
THE HIGH SPREADING ACROSS THE UPPER MS VALLEY INTO THE GREAT LAKES
AND A NORTHEAST LOW LEVEL TRAJECTORY...DRY AIR WILL NEED TO BE
OVERCOME BEFORE PRECIP CAN SPREAD INTO THE SOUTHERN CWA TONIGHT.
EXPECT A SHARP CUTOFF TO THE PRECIP ON ITS NORTHERN FLANK AND AM
THINKING THAT PRECIP WILL ARRIVE ALONG AND SOUTH OF A
PONTIAC-KANKAKEE-RENSSELAER LINE TOWARD 06Z THEN MAKE SLOW NORTHWARD
PROGRESS THROUGH DAYBREAK. EXPECT PRECIP TYPE IN THESE AREAS TO BE
ALL RAIN BUT TYPE BECOMES MORE OF A CHALLENGE TO THE NORTH TUESDAY
MORNING. FORCING LOOKS TO BECOME LESS ORGANIZED TOWARDS INTERSTATE
80 BUT THERE WILL BE A THREAT FOR LIGHT PRECIP STARTING TUESDAY
MORNING. SURFACE TEMPS NORTH OF THE PNT-IKK-RZL LINE WILL PROBABLY
BE AT OR JUST BELOW FREEZING AND COOL SLIGHTLY NORTHWARD TOWARD
I-80. BASED ON FORECAST SOUNDINGS PRECIP WOULD LIKELY START OUT AS
SNOW BUT MAY TRANSITION TO RAIN OR FREEZING RAIN AS THE MID LEVELS
WARM BUT THE COOL/DRY NORTHEASTERLY LOW LEVEL FLOW CONTINUES
UNDERNEATH. LOW LEVEL TEMPS WILL WARM DIURNALLY HOWEVER...AND A
CHANGE OVER TO PRIMARILY RAIN IS EXPECTED TOWARD MIDDAY. LOW PRECIP
CHANCES WILL SPREAD NORTHWARD THE IL/WI BORDER INTO EARLY AFTERNOON
WITH SLIGHTLY WARMING TEMP PROFILES SUPPORTING A RAIN SNOW MIX FROM
ROUGHLY INTERSTATE 88 NORTH.
TUESDAY NIGHT AND WEDNESDAY...THE UPPER LOW WILL BE OVER NORTHEAST
KANSAS WITH THE SURFACE LOW SOMEWHERE OVER SOUTHERN OR SOUTHEAST
MISSOURI. PRETTY GOOD MODEL AGREEMENT ON A DRY PUSH OF AIR LIFTING
NORTHEASTWARD TOWARD LAKE MICHIGAN LATE TUESDAY AFTERNOON AND EARLY
TUESDAY EVENING WHICH SHOULD LIMIT PRECIP CHANCES SOMEWHAT THROUGH
THE EVENING AND POSSIBLY INTO THE EARLY OVERNIGHT. PRECIP TYPE
DURING THIS TIME SHOULD BE RAIN...EXCEPT FAR NORTHWEST WHERE RAIN
AND SNOW MAY MIX. THINGS BECOME MORE CHALLENGING OVERNIGHT AND
WEDNESDAY MORNING AS THE SURFACE LOW PASSES TO THE SOUTHEAST AND THE
UPPER LOW LIFTS NORTHEAST RIGHT ACROSS THE AREA. MID LEVEL FORCING
WILL INCREASE AS DEFORMATION DEVELOPS IN CONJUNCTION WITH Q-VECTOR
CONVERGENCE RESULTING IN ADDITIONAL BANDS OF PRECIP SPREADING IN
FROM THE SOUTHWEST AFTER MIDNIGHT THROUGH MUCH OF WEDNESDAY MORNING.
COLDER AIR WILL WRAP IN...ESPECIALLY ALOFT...LEADING TO A TOUGH
P-TYPE FORECAST. RIGHT NOW EXPECT THAT RAIN WILL MIX WITH AND
POSSIBLY CHANGE TO SNOW INTO WEDNESDAY MORNING ACROSS THE
NORTHWESTERN HALF OF THE AREA OR ROUGHLY WEST OF A CHICAGO TO
PONTIAC LINE...WITH A BETTER CHANCE FOR ALL RAIN TO THE EAST BUT A
MIX MAY OCCUR AS WELL. MODEL AGREEMENT IS SOMEWHAT LACKING IN TERMS
OF THE THERMAL PROFILE SO CONFIDENCE IS LIMITED IN THE DETAILS.
CONCEPTUALLY SPEAKING...AM ALSO CONCERNED THAT IF FORCING CAN BECOME
STRONG THEN DYNAMIC COOLING PROCESSES UNDER THE CORE OF COLDEST AIR
MAY RESULT IN A BAND OF ALL SNOW...WHICH COULD BECOME SOMEWHAT
INTENSE FOR A SHORT TIME. THIS WOULD BE FAST MOVING BUT A STRIPE OF
LOW END ACCUMULATION MAY OCCUR. COLD ADVECTION BEHIND THE DEPARTING
TROUGH IS NOT TERRIBLY STRONG GIVEN THAT WEAK UPPER RIDGING WILL
BUILD IN BEHIND IT SO WE MAY SEE SOME DIURNAL WARMING...ESPECIALLY
IF CLOUDS CAN BREAK UP.
THURSDAY THROUGH MONDAY...WEAK UPPER RIDGING WILL DAMPEN OVER THE
AREA WITH ANOTHER UPPER TROUGH SPREADING ACROSS THE FOUR CORNERS
INTO THE CENTRAL ROCKIES. THE UPPER FLOW LOOKS TO BE AT LEAST
SOMEWHAT SPLIT WITH A TROUGH ACROSS SOUTHERN CANADA. THIS MAY RESULT
IN A TIGHTENING MID LEVEL TEMP GRADIENT FROM SOUTHERN QUEBEC BACK
TOWARDS NEBRASKA THURSDAY WHICH WILL THEN SETTLE SOUTHWARD INTO THE
AREA THURSDAY NIGHT. DOES NOT APPEAR TO BE MUCH FORCING ASSOCIATED
WITH THIS BUT WILL NEED TO WATCH THE NEED FOR LOW PRECIP CHANCES.
THE SOUTHERN STREAM TROUGH WILL TRACK EAST-NORTHEASTWARD ACROSS THE
MID MISSISSIPPI RIVER VALLEY AND PUSH A SURFACE LOW NORTHEASTWARD
SOMEWHERE ACROSS THE OHIO VALLEY SATURDAY. THE ECMWF AND GFS ARE IN
REASONABLE AGREEMENT WITH THE EXISTENCE OF THESE FEATURES BUT DIFFER
ON TRACK WHICH HAS A SIGNIFICANT IMPACT ON OUR SENSIBLE WEATHER. A
WESTERLY TRACK WOULD BRING SNOW TO THE AREA FRIDAY NIGHT AND
SATURDAY. TOO EARLY FOR ANY KIND OF DETAILS BUT MOISTURE CONTENT
DOES NOT LOOK TERRIBLY HIGH SO ACCUMULATION MAY BE MINIMAL SHOULD
PRECIP OCCUR. BEYOND THAT...ANOTHER TROUGH LOOKS TO FOLLOW THE FIRST
BRINGING A PUSH OF NOTICEABLY COLDER AIR IN FOR SUNDAY BUT LARGE
SCALE RIDGING LOOKS TO QUICKLY BRING MILDER AIR BACK TO THE REGION
EARLY NEXT WEEK.
MDB
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 20Z...
* ONGOING FROPA...MVFR CIGS BEHIND THE FRONT
* WIND SHIFT TO WEST THEN NORTHWEST...THEN NORTHEAST
* OCCNL WIND GUSTS THIS AFTERNOON
* PRECIP CHANCES/TYPE TUES MORNING
SHEA
//DISCUSSION...20Z UPDATE...
DID FURTHER TWEAKING TO THE CIG AND WIND FORECAST...EXPECT WINDS
TO CONTINUE TO FLIP AROUND TO THE NORTH AND NORTHEAST OVER THE
COURSE OF THE NEXT FEW HOURS. RUC/NAM AND HRRR GUIDANCE ALL
INDICATE IT OCCURRING IN THE 21-22Z HOUR. MKE AND RAC HAVE ALREADY
FLIPPED FROM 310 TO 350 TO 030 OVER THE COURSE OF A FEW HOURS.
EXPECT TO SEE ENW NEXT...FOLLOWED BY UGN...PWK AND THEN ORD/MDW.
CURRENTLY SEE A RARE DECEMBER LAKE BREEZE ON TORD...AND TIMING
TROUGH ORD/MDW LOOKS TO BE RIGHT IN LINE WITH EARLIER
THINKING...AND AROUND THE 2130 HOUR. OTHERWISE CIG TRENDS DO NOT
LOOK SUPPORTIVE OF LOW END MVFR...AND TRENDED THAT WAY.
SHEA
//DISCUSSION...PREVIOUS 18Z...
VFR CONDITIONS FOR THE TERMINALS WILL BE QUICKLY COMING TO A CLOSE
AS STRATUS SLIDES IN FROM THE NORTH BEHIND A FRONT THAT IS
CURRENTLY SHIFTING THROUGH THE REGION. WINDS AHEAD OF THE FRONT
WILL RANGE FROM 250-280 DEGREES...VEERING TO THE 320 TO 340 RANGE
BEHIND IT. WINDS ARE EXPECTED TO MAINTAIN THE MID TO UPPER TEEN
GUSTS THROUGH THE AFTERNOON AND INTO THE EVENING HOURS. MOST
LOCATIONS WILL SEE THE FRONT SLIDE THROUGH WITHIN THE HOUR...WITH
GYY BEING THE EXCEPTION...JUST ANOTHER HOUR BEYOND. THE MAIN PUSH
OF STRATUS FROM THE NORTH HAD BEEN PRETTY WELL TIMED TO BE AT OR
BEYOND THE 20-21Z HOUR...BUT THE LATEST VISIBLE SATELLITE IMAGERY
IS SHOWING A BIT OF AN ACCELERATION ALONG THE LEADING EDGE. MAY
NEED TO TWEAK THE TIMING OF THE MVFR CIGS SLIGHTLY FOR THE 20Z
AMD. EXPECT CIGS TO FALL INTO THE 015-018 RANGE FOR A FEW HOURS
ONCE IT MOVES THROUGH... BUT INDICATIONS POINT TOWARDS A LEVELING
OFF AND GRADUAL RISE A FEW HOURS BEHIND TO MID AND UPPER LEVEL
MVFR. NOT OVERLY CONFIDENT THAT CIGS WILL FALL TO LOW END MVFR OR
IFR RANGE...BUT THERE IS THE POSSIBILITY THAT COULD HAPPEN FOR A
VERY SHORT TIME. WINDS WILL THEN CONTINUE TO WORK AROUND THE
COMPASS DIAL...GRADUALLY REACHING NORTH...NORTHEAST AND EAST BY
TOMORROW MORNING. THE NEXT CHANCES FOR PRECIP WILL ARRIVE
TOMORROW... AS ANOTHER SYSTEM LIFTS OUT OF THE MISSISSIPPI VALLEY.
THERE ARE STILL SOME UNCERTAIN VARIABLES PERTAINING TO TIMING /AS
TRENDS HAVE BEEN SLOWING/ AS WELL AS P-TYPE.
SHEA
//ORD AND MDW CONFIDENCE...UPDATED 18Z...
* MOD-HIGH CONFIDENCE IN CIG TREND/TIMING FORECAST
** LOW CONFIDENCE ON LOW END MVFR CIG POTENTIAL
* MOD-HIGH CONFIDENCE ON WIND FORECAST
* LOW CONFIDENCE ON PRECIP TYPE/TIMING TUES MORNING
SHEA
//OUTLOOK FOR ORD/MDW FOR 00Z WEDNESDAY-12Z MONDAY...UPDATED 12Z...
TUESDAY NIGHT...RAIN LIKELY. MVFR/IFR CIGS.
WEDNESDAY...CHC OF RAIN AND SNOW. MVFR CIGS BECOMING VFR LATE.
THURSDAY...MAINLY VFR. SCHC OF FLURRIES/MVFR CIGS LATE.
FRIDAY...MVFR WITH A CHC OF SNOW LATE.
SATURDAY...SCHC RAIN OR SNOW THEN SCHC OF SNOW LATE. MVFR/IFR CIGS.
SUNDAY...MVFR CIGS BECOMING VFR.
JEE
&&
.MARINE...
206 AM CST
SOUTHWESTERLY GALES WILL CONTINUE FOR THE NEXT FEW HOURS AHEAD OF AN
APPROACHING COLD FRONT. AS THE FRONT PASSES ACROSS THE LAKE THIS
MORNING AND EARLY AFTERNOON...THE WINDS WILL VEER OUT OF THE NORTH
TO 20 TO 25 KT. A SURFACE RIDGE OF HIGH PRESSURE WILL PUSH ACROSS THE
LAKE MONDAY NIGHT INTO TUESDAY AS LOW PRESSURE TAKES SHAPE ACROSS
THE SOUTHERN PLAINS. THIS LOW WILL EVENTUALLY TRACK NORTHEASTWARD
ACROSS THE OHIO VALLEY BY WEDNESDAY.
LATER IN THE WEEK ANOTHER COLD FRONT LOOKS TO DROP SOUTH OUT OF
CANADA AND ACROSS LAKE MICHIGAN. HIGH PRESSURE BUILDING ACROSS THE
PLAINS SHOULD SET UP A DECENT GRADIENT ACROSS THE LAKE. THIS COULD
LEAD TO A PERIOD OF 15 TO 25 KT WINDS LATE THURSDAY INTO FRIDAY
BEFORE THE HIGH SHIFTS EAST ACROSS THE GREAT LAKES.
KJB
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...SMALL CRAFT ADVISORY...LMZ740-LMZ741-LMZ742-LMZ743-LMZ744-
LMZ745...6 PM MONDAY TO 10 AM TUESDAY.
&&
$$
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
133 PM CST MON DEC 19 2011
.DISCUSSION...
319 AM CST
THE MAIN FORECAST CONCERNS CENTER AROUND PRECIP TYPE AND COVERAGE
TONIGHT INTO WEDNESDAY AS LOW PRESSURE MOVES NORTHEASTWARD FROM
NORTHERN TEXAS TO NORTHERN OHIO IN CONJUNCTION WITH AN UPPER LOW.
SATELLITE MOISTURE CHANNEL IMAGERY SHOWS SEVERAL KEY FEATURES THAT
WILL DRIVE OUR WEATHER THROUGH MID-WEEK. THE FIRST IS A LOW
AMPLITUDE UPPER LEVEL TROUGH EXTENDING FROM HUDSON BAY SOUTHWESTWARD
AND MOVING TO THE EAST. A SECOND WAVE IN THE UPPER FLOW IS
POSITIONED JUST TO THE SOUTHWEST OF THE FIRST FROM CENTRAL MANITOBA
SOUTHWESTWARD INTO THE NORTHERN U.S. ROCKIES. THE NEXT AND MOST
SIGNIFICANT FEATURE IS THE CUTOFF UPPER LOW SPINNING OVER THE
ARIZONA/NEW MEXICO/MEXICO BORDER WHICH WILL LIFT NORTHEASTWARD AND BRING
US A MIX OF PRECIPITATION TUESDAY AND WEDNESDAY. AT THE
SURFACE...LOW PRESSURE JUST NORTHEAST OF LAKE SUPERIOR ASSOCIATED
WITH THE HUDSON BAY REGION TROUGH CONTINUES TO MOVE EASTWARD WITH A
COLD FRONT EXTENDING SOUTHWESTWARD ACROSS NORTHERN LAKE
HURON...SOUTHERN LAKE MICHIGAN AND BACK INTO NORTHEAST KANSAS.
PRESSURE FALLS ARE ALSO FOUND ACROSS NEW MEXICO AND WEST TEXAS IN
CONJUNCTION WITH THE APPROACHING UPPER LOW.
TODAY AND TONIGHT...MILD AND MOIST SOUTHWESTERLY LOW LEVEL FLOW
CONTINUES ACROSS THE AREA EARLY THIS MORNING AHEAD OF THE
APPROACHING FRONTAL BOUNDARY. TEMPS HAD RISEN SEVERAL DEGREES SINCE
LAST EVENING WITH BREEZY SOUTHWEST WINDS GUSTING TO AROUND 20 KT AND
AN INFLUX OF CLOUD COVER. SPEEDS HAVE STARTED TO SLACKEN SOMEWHAT AS
THE GRADIENT WEAKENS SLIGHTLY AS THE FRONTAL TROUGH APPROACHES SO
TEMPS MAY DROP A FEW DEGREES THROUGH DAYBREAK. THE FRONT WILL CROSS
THE AREA THIS MORNING SHIFTING WINDS TO THE NORTHWEST THEN NORTH.
TEMPS PROBABLY WILL NOT WARM MUCH NORTHWEST WITH MODEST COLD
ADVECTION BUILDING IN BUT SOUTHEASTERN AREAS SHOULD SEE HIGHS A FEW
DEGREES WARMER THAN MORNING TEMPS. MAY SEE TEMPS DROP A FEW DEGREES
DURING THE AFTERNOON IN THE NORTHWEST. LOW CLOUD COVER WILL BE
PERSISTENT THROUGH THE DAY BUT NORTHWEST AREAS WILL LIKELY SEE SOME
BREAKS OF SUNSHINE. FRONTAL FORCING IS WEAK BUT MOISTURE WILL
CONTINUE TO STREAM NORTHEASTWARD ACROSS THE EASTERN HALF OF THE AREA
WITH DECENT HEIGHT FALLS OCCURRING ALOFT. WILL CONTINUE SLIGHT
CHANCE FOR SPRINKLES FAR SOUTH AND EAST.
TONIGHT AND TUESDAY...HIGH PRESSURE WILL SPREAD ACROSS THE NORTHERN PLAINS
AND UPPER MISSISSIPPI RIVER VALLEY INTO THIS EVENING WITH THE
SOUTHERN PERIPHERY PUSHING INTO NORTHERN ILLINOIS. THE COOL FRONT
WILL STALL OUT FROM NORTHERN OHIO SOUTHWEST ACROSS CENTRAL ILLINOIS
AND BACK INTO NORTHEAST OKLAHOMA JOINING UP WITH DEVELOPING LOW
PRESSURE OVER THE TX/OK BORDER. A SHARP MID LEVEL BAROCLINIC ZONE
WILL SET UP FROM NORTHERN OHIO BACK ACROSS CENTRAL ILLINOIS AND
NORTHERN MISSOURI AS THE MANITOBA UPPER TROUGH TRANSLATES ACROSS THE
GREAT LAKES AND BROAD UPPER RIDGING PIVOTS EASTWARD ACROSS THE LOWER
MISSISSIPPI RIVER VALLEY AHEAD OF THE APPROACHING UPPER LOW. HIGH
THETA-E AIR WILL STREAM NORTHWARD INTO THE TEMP GRADIENT RESULTING
IN A BLOSSOMING OF PRECIPITATION ALONG IT STARTING THIS TODAY. WITH
THE HIGH SPREADING ACROSS THE UPPER MS VALLEY INTO THE GREAT LAKES
AND A NORTHEAST LOW LEVEL TRAJECTORY...DRY AIR WILL NEED TO BE
OVERCOME BEFORE PRECIP CAN SPREAD INTO THE SOUTHERN CWA TONIGHT.
EXPECT A SHARP CUTOFF TO THE PRECIP ON ITS NORTHERN FLANK AND AM
THINKING THAT PRECIP WILL ARRIVE ALONG AND SOUTH OF A
PONTIAC-KANKAKEE-RENSSELAER LINE TOWARD 06Z THEN MAKE SLOW NORTHWARD
PROGRESS THROUGH DAYBREAK. EXPECT PRECIP TYPE IN THESE AREAS TO BE
ALL RAIN BUT TYPE BECOMES MORE OF A CHALLENGE TO THE NORTH TUESDAY
MORNING. FORCING LOOKS TO BECOME LESS ORGANIZED TOWARDS INTERSTATE
80 BUT THERE WILL BE A THREAT FOR LIGHT PRECIP STARTING TUESDAY
MORNING. SURFACE TEMPS NORTH OF THE PNT-IKK-RZL LINE WILL PROBABLY
BE AT OR JUST BELOW FREEZING AND COOL SLIGHTLY NORTHWARD TOWARD
I-80. BASED ON FORECAST SOUNDINGS PRECIP WOULD LIKELY START OUT AS
SNOW BUT MAY TRANSITION TO RAIN OR FREEZING RAIN AS THE MID LEVELS
WARM BUT THE COOL/DRY NORTHEASTERLY LOW LEVEL FLOW CONTINUES
UNDERNEATH. LOW LEVEL TEMPS WILL WARM DIURNALLY HOWEVER...AND A
CHANGE OVER TO PRIMARILY RAIN IS EXPECTED TOWARD MIDDAY. LOW PRECIP
CHANCES WILL SPREAD NORTHWARD THE IL/WI BORDER INTO EARLY AFTERNOON
WITH SLIGHTLY WARMING TEMP PROFILES SUPPORTING A RAIN SNOW MIX FROM
ROUGHLY INTERSTATE 88 NORTH.
TUESDAY NIGHT AND WEDNESDAY...THE UPPER LOW WILL BE OVER NORTHEAST
KANSAS WITH THE SURFACE LOW SOMEWHERE OVER SOUTHERN OR SOUTHEAST
MISSOURI. PRETTY GOOD MODEL AGREEMENT ON A DRY PUSH OF AIR LIFTING
NORTHEASTWARD TOWARD LAKE MICHIGAN LATE TUESDAY AFTERNOON AND EARLY
TUESDAY EVENING WHICH SHOULD LIMIT PRECIP CHANCES SOMEWHAT THROUGH
THE EVENING AND POSSIBLY INTO THE EARLY OVERNIGHT. PRECIP TYPE
DURING THIS TIME SHOULD BE RAIN...EXCEPT FAR NORTHWEST WHERE RAIN
AND SNOW MAY MIX. THINGS BECOME MORE CHALLENGING OVERNIGHT AND
WEDNESDAY MORNING AS THE SURFACE LOW PASSES TO THE SOUTHEAST AND THE
UPPER LOW LIFTS NORTHEAST RIGHT ACROSS THE AREA. MID LEVEL FORCING
WILL INCREASE AS DEFORMATION DEVELOPS IN CONJUNCTION WITH Q-VECTOR
CONVERGENCE RESULTING IN ADDITIONAL BANDS OF PRECIP SPREADING IN
FROM THE SOUTHWEST AFTER MIDNIGHT THROUGH MUCH OF WEDNESDAY MORNING.
COLDER AIR WILL WRAP IN...ESPECIALLY ALOFT...LEADING TO A TOUGH
P-TYPE FORECAST. RIGHT NOW EXPECT THAT RAIN WILL MIX WITH AND
POSSIBLY CHANGE TO SNOW INTO WEDNESDAY MORNING ACROSS THE
NORTHWESTERN HALF OF THE AREA OR ROUGHLY WEST OF A CHICAGO TO
PONTIAC LINE...WITH A BETTER CHANCE FOR ALL RAIN TO THE EAST BUT A
MIX MAY OCCUR AS WELL. MODEL AGREEMENT IS SOMEWHAT LACKING IN TERMS
OF THE THERMAL PROFILE SO CONFIDENCE IS LIMITED IN THE DETAILS.
CONCEPTUALLY SPEAKING...AM ALSO CONCERNED THAT IF FORCING CAN BECOME
STRONG THEN DYNAMIC COOLING PROCESSES UNDER THE CORE OF COLDEST AIR
MAY RESULT IN A BAND OF ALL SNOW...WHICH COULD BECOME SOMEWHAT
INTENSE FOR A SHORT TIME. THIS WOULD BE FAST MOVING BUT A STRIPE OF
LOW END ACCUMULATION MAY OCCUR. COLD ADVECTION BEHIND THE DEPARTING
TROUGH IS NOT TERRIBLY STRONG GIVEN THAT WEAK UPPER RIDGING WILL
BUILD IN BEHIND IT SO WE MAY SEE SOME DIURNAL WARMING...ESPECIALLY
IF CLOUDS CAN BREAK UP.
THURSDAY THROUGH MONDAY...WEAK UPPER RIDGING WILL DAMPEN OVER THE
AREA WITH ANOTHER UPPER TROUGH SPREADING ACROSS THE FOUR CORNERS
INTO THE CENTRAL ROCKIES. THE UPPER FLOW LOOKS TO BE AT LEAST
SOMEWHAT SPLIT WITH A TROUGH ACROSS SOUTHERN CANADA. THIS MAY RESULT
IN A TIGHTENING MID LEVEL TEMP GRADIENT FROM SOUTHERN QUEBEC BACK
TOWARDS NEBRASKA THURSDAY WHICH WILL THEN SETTLE SOUTHWARD INTO THE
AREA THURSDAY NIGHT. DOES NOT APPEAR TO BE MUCH FORCING ASSOCIATED
WITH THIS BUT WILL NEED TO WATCH THE NEED FOR LOW PRECIP CHANCES.
THE SOUTHERN STREAM TROUGH WILL TRACK EAST-NORTHEASTWARD ACROSS THE
MID MISSISSIPPI RIVER VALLEY AND PUSH A SURFACE LOW NORTHEASTWARD
SOMEWHERE ACROSS THE OHIO VALLEY SATURDAY. THE ECMWF AND GFS ARE IN
REASONABLE AGREEMENT WITH THE EXISTENCE OF THESE FEATURES BUT DIFFER
ON TRACK WHICH HAS A SIGNIFICANT IMPACT ON OUR SENSIBLE WEATHER. A
WESTERLY TRACK WOULD BRING SNOW TO THE AREA FRIDAY NIGHT AND
SATURDAY. TOO EARLY FOR ANY KIND OF DETAILS BUT MOISTURE CONTENT
DOES NOT LOOK TERRIBLY HIGH SO ACCUMULATION MAY BE MINIMAL SHOULD
PRECIP OCCUR. BEYOND THAT...ANOTHER TROUGH LOOKS TO FOLLOW THE FIRST
BRINGING A PUSH OF NOTICEABLY COLDER AIR IN FOR SUNDAY BUT LARGE
SCALE RIDGING LOOKS TO QUICKLY BRING MILDER AIR BACK TO THE REGION
EARLY NEXT WEEK.
MDB
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 18Z...
* ONGOING FROPA...MVFR CIGS BEHIND THE FRONT
* WIND SHIFT TO WEST THEN NORTHWEST...THEN NORTHEAST
* WIND GUSTS IN THE LOW 20 KT RANGE THIS AFTERNOON
* PRECIP CHANCES/TYPE TUES MORNING
SHEA
//DISCUSSION...19Z UPDATE...
DID FURTHER TWEAKING TO THE CIG AND WIND FORECAST...EXPECT WINDS
TO CONTINUE TO FLIP AROUND TO THE NORTH AND NORTHEAST OVER THE
COURSE OF THE NEXT FEW HOURS. RUC/NAM AND HRRR GUIDANCE ALL
INDICATE IT OCCURRING IN THE 21-22Z HOUR. MKE AND RAC HAVE ALREADY
FLIPPED FROM 310 TO 350 TO 030 OVER THE COURSE OF A FEW HOURS.
EXPECT TO SEE ENW NEXT...FOLLOWED BY UGN...PWK AND THEN ORD/MDW.
SHEA
//DISCUSSION...PREVIOUS 18Z...
VFR CONDITIONS FOR THE TERMINALS WILL BE QUICKLY COMING TO A CLOSE
AS STRATUS SLIDES IN FROM THE NORTH BEHIND A FRONT THAT IS
CURRENTLY SHIFTING THROUGH THE REGION. WINDS AHEAD OF THE FRONT
WILL RANGE FROM 250-280 DEGREES...VEERING TO THE 320 TO 340 RANGE
BEHIND IT. WINDS ARE EXPECTED TO MAINTAIN THE MID TO UPPER TEEN
GUSTS THROUGH THE AFTERNOON AND INTO THE EVENING HOURS. MOST
LOCATIONS WILL SEE THE FRONT SLIDE THROUGH WITHIN THE HOUR...WITH
GYY BEING THE EXCEPTION...JUST ANOTHER HOUR BEYOND. THE MAIN PUSH
OF STRATUS FROM THE NORTH HAD BEEN PRETTY WELL TIMED TO BE AT OR
BEYOND THE 20-21Z HOUR...BUT THE LATEST VISIBLE SATELLITE IMAGERY
IS SHOWING A BIT OF AN ACCELERATION ALONG THE LEADING EDGE. MAY
NEED TO TWEAK THE TIMING OF THE MVFR CIGS SLIGHTLY FOR THE 20Z
AMD. EXPECT CIGS TO FALL INTO THE 015-018 RANGE FOR A FEW HOURS
ONCE IT MOVES THROUGH... BUT INDICATIONS POINT TOWARDS A LEVELING
OFF AND GRADUAL RISE A FEW HOURS BEHIND TO MID AND UPPER LEVEL
MVFR. NOT OVERLY CONFIDENT THAT CIGS WILL FALL TO LOW END MVFR OR
IFR RANGE...BUT THERE IS THE POSSIBILITY THAT COULD HAPPEN FOR A
VERY SHORT TIME. WINDS WILL THEN CONTINUE TO WORK AROUND THE
COMPASS DIAL...GRADUALLY REACHING NORTH...NORTHEAST AND EAST BY
TOMORROW MORNING. THE NEXT CHANCES FOR PRECIP WILL ARRIVE
TOMORROW... AS ANOTHER SYSTEM LIFTS OUT OF THE MISSISSIPPI VALLEY.
THERE ARE STILL SOME UNCERTAIN VARIABLES PERTAINING TO TIMING /AS
TRENDS HAVE BEEN SLOWING/ AS WELL AS P-TYPE.
SHEA
//ORD AND MDW CONFIDENCE...UPDATED 18Z...
* MOD-HIGH CONFIDENCE IN CIG TREND/TIMING FORECAST
** LOW CONFIDENCE ON LOW END MVFR CIG POTENTIAL
* MOD-HIGH CONFIDENCE ON WIND FORECAST
* LOW CONFIDENCE ON PRECIP TYPE/TIMING TUES MORNING
SHEA
//OUTLOOK FOR ORD/MDW FOR 00Z WEDNESDAY-12Z MONDAY...UPDATED 12Z...
TUESDAY NIGHT...RAIN LIKELY. MVFR/IFR CIGS.
WEDNESDAY...CHC OF RAIN AND SNOW. MVFR CIGS BECOMING VFR LATE.
THURSDAY...MAINLY VFR. SCHC OF FLURRIES/MVFR CIGS LATE.
FRIDAY...MVFR WITH A CHC OF SNOW LATE.
SATURDAY...SCHC RAIN OR SNOW THEN SCHC OF SNOW LATE. MVFR/IFR CIGS.
SUNDAY...MVFR CIGS BECOMING VFR.
JEE
&&
.MARINE...
206 AM CST
SOUTHWESTERLY GALES WILL CONTINUE FOR THE NEXT FEW HOURS AHEAD OF AN
APPROACHING COLD FRONT. AS THE FRONT PASSES ACROSS THE LAKE THIS
MORNING AND EARLY AFTERNOON...THE WINDS WILL VEER OUT OF THE NORTH
TO 20 TO 25 KT. A SURFACE RIDGE OF HIGH PRESSURE WILL PUSH ACROSS THE
LAKE MONDAY NIGHT INTO TUESDAY AS LOW PRESSURE TAKES SHAPE ACROSS
THE SOUTHERN PLAINS. THIS LOW WILL EVENTUALLY TRACK NORTHEASTWARD
ACROSS THE OHIO VALLEY BY WEDNESDAY.
LATER IN THE WEEK ANOTHER COLD FRONT LOOKS TO DROP SOUTH OUT OF
CANADA AND ACROSS LAKE MICHIGAN. HIGH PRESSURE BUILDING ACROSS THE
PLAINS SHOULD SET UP A DECENT GRADIENT ACROSS THE LAKE. THIS COULD
LEAD TO A PERIOD OF 15 TO 25 KT WINDS LATE THURSDAY INTO FRIDAY
BEFORE THE HIGH SHIFTS EAST ACROSS THE GREAT LAKES.
KJB
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...SMALL CRAFT ADVISORY...LMZ740-LMZ741-LMZ742-LMZ743-LMZ744-
LMZ745...6 PM MONDAY TO 10 AM TUESDAY.
&&
$$
AREA FORECAST DISCUSSION...CORRECTION TO TYPO...
NWS QUAD CITIES IA IL
315 PM CST MON DEC 19 2011
.SYNOPSIS...
12Z UA ANALYSIS HAD THE STORM SYSTEM DEVELOPING IN THE SOUTHERN
ROCKIES WITH A LLJ OF 40-50 KNOTS TRANSPORTING MOISTURE NORTH INTO
THE PLAINS AND OHIO VALLEY. AN 850MB COLD FRONT RAN FROM NORTHERN
LAKE HURON INTO NORTHEAST COLORADO. SATELLITE AND RADAR TRENDS
THROUGH MID AFTERNOON SHOWED INCREASING CLOUDS ACROSS THE AREA WITH
PRECIPITATION GENERALLY SOUTH OF A KSTJ TO KUIN LINE.
18Z SFC ANALYSIS HAD A COLD FRONT RUNNING FROM KOSC...TO KMCI...TO
AROUND KDHT. LOW PRESSURES FROM THE DEVELOPING STORM SYSTEM WERE
SOUTH OF KTCC AND NEAR KPPA. DEW POINTS WERE IN THE 40S JUST AHEAD
OF THE COLD FRONT INTO THE OHIO VALLEY WITH 50S CROSSING THE RED
RIVER INTO OKLAHOMA. DEW POINTS IN THE 20S AND 30S WERE ACROSS MUCH
OF THE NORTHERN/CENTRAL PLAINS AND UPPER MIDWEST.
&&
.SHORT TERM...TONIGHT AND TUESDAY...
THE MAIN QUESTION IS HOW LONG WILL THE DRY AIR KEEP THE
PRECIPITATION AT BAY TONIGHT INTO TUESDAY. BASED ON 12Z UA DATA...
THE WRF INITIALIZED A LITTLE BETTER THAN THE OTHER MODELS BASED ON
LOW LEVEL MOISTURE.
CONDENSATION PRESSURE DEFICITS ON EITHER STANDARD SURFACES OR THE
290-925K THETA SFC HAVE BEEN DEPICTING WELL THE AREAL COVERAGE OF
THE PRECIPITATION LATE THIS MORNING AND AFTERNOON. ALL MODELS HAVE
GENERALLY SHOWED THIS BUT THE RUC TRENDS HAVE DONE VERY WELL AND THE
RUC WILL BE USED FOR THE IMMEDIATE SHORT TERM.
BASED ON THE RUC CONDENSATION PRESSURE DEFICIT TRENDS...THE EARLY
EVENING WILL REMAIN DRY ACROSS THE ENTIRE AREA. BETWEEN 9 PM AND
MIDNIGHT PRECIPITATION WILL ADVECT/DEVELOP GENERALLY SOUTH OF A KOTM
TO KPIA LINE. FCST SOUNDINGS SHOW A TOP DOWN SATURATION TAKING PLACE
SO THERE WILL BE PLENTY OF EVAPORATIVE COOLING TAKING PLACE. THUS A
RAIN/SNOW MIX WILL DEVELOP THAT WILL LIKELY HAVE A BRIEF PERIOD OF
SLEET AS THE PRECIPITATION DEVELOPS. THERE IS A CONCERN BASED ON HOW
WARM IT HAS GOTTEN TODAY THAT PTYPE COULD BE MORE LIQUID THAN
FREEZING OR FROZEN.
AFTER MIDNIGHT...THE PRECIPITATION SHIELD WILL SLOWLY MOVE
NORTHWARD...REACHING A KOTM TO KGBG LINE AROUND 3 AM AND ROUGHLY A
KOOA TO KC75 LINE AROUND 12Z. THE I-80 CORRIDOR ON NORTH WILL REMAIN
DRY THROUGH SUNRISE. MINS TONIGHT WILL BE HIGHLY DEPENDENT ON CLOUD
COVER AND HOW THE PRECIPITATION SHIELD EVOLVES.
SNOW AMOUNTS SHOULD BE ONE HALF INCH OR LESS TONIGHT.
ON TUESDAY...THE PRECIPITATION SHIELD WILL CONTINUE MOVING NORTH AND
REACH I-80 ROUGHLY AROUND 9 AM AND SHOULD BE AROUND A VINTON TO MT
CARROLL LINE BY MID DAY. THE IMMEDIATE HWY 20 CORRIDOR IS EXPECTED
REMAIN DRY DURING THE MORNING HOURS. EVAPORATIVE COOLING WILL
CONTINUE TO PLAY SIGNIFICANTLY IN PTYPE WITH A RAIN/SNOW MIX ALONG
WITH A BRIEF PERIOD OF SLEET.
BY LATE MORNING AND INTO THE AFTERNOON HOURS...THE OVERALL FORCING
ACROSS THE AREA DECREASES. THE OVERALL PRECIPITATION INTENSITY WILL
LET UP AND A CHANGE OVER TO MAINLY RAIN IS EXPECTED EXCEPT ACROSS
ROUGHLY THE NORTHWEST THIRD OR SO OF THE CWFA WHERE A MIX IS STILL
EXPECTED. THE RAIN MAY STOP OR GO TO MORE DRIZZLE DURING THE
AFTERNOON HOURS.
SNOW AMOUNTS ON TUESDAY SHOULD BE ONE HALF INCH OR LESS. ..08..
.LONG TERM...TUESDAY NIGHT THROUGH NEXT MONDAY...
TUESDAY NIGHT AND WEDNESDAY...LATEST 12Z RUNS HAVE SHIFTED SLIGHTLY
BACK SOUTHWARD WITH RESPECT TO MAIN SFC LOW AND MID LEVEL
PROPAGATION PATHS LATER TUE THROUGH WED. WILL SIDE THE NEW 12Z RUN
ECMWF AND NAM WHICH ARE IN GOOD AGREEMENT WITH THEIR MASS FIELDS
WITH EACH OTHER AND THERE SOLUTIONS ARE IN THE MIDDLE OF THE ROAD OF
THE ENSEMBLES OF THESE FEATURES. THESE ACCEPTED SOLUTIONS SUGGEST
THAT THE SFC LOW WILL BE ACRS FAR SOUTHWEST MO AT 00Z WED...AND MOVE
NORTHEASTWARD TO THE EAST CENTRAL IL/WEST CENTRAL INDIANA BORDER
REGION BY 12Z WED WITH EYES ON THE WESTERN BASIN OF LK ERIE BY
MIDDAY WED. UPPER LOW TILTED TO THE NORTHWEST OF THE LLVL CYCLONE
WILL STILL LOOK TO PROGRESS ACRS THE SOUTHWEST HALF OF THE CWA BY
WED MORNING STILL IN A CLOSED FASHION AND THEN LOOK TO OPEN UP ON
THE WAY TO OVER THE SOUTH HALF OF LK MI BY WED AFTERNOON. ACCEPTED
THERMAL PROFILES SUGGEST LIGHT RAIN ACRS THE SOUTHEAST HALF OF THE
DVN CWA TUE EVENING WITH SOME SLEET POSSIBLY MIXED IN THE NORTHERN
FRINGE OF THE RAIN AT SFC BAND UP ALONG THE SOUTHERN I80 CORRIDOR.
WITH THE MODELS STILL SUGGESTING THE MAIN THRUST OF WARM MOIST
CONVEYOR SHUNTED OFF TO THE EAST AND SOUTHEAST OF THE AREA BY LATE
TUE...THE APPROACHING UPPER LOW WILL ONLY HAVE TO WORK WITH
SECONDARY MOISTURE FEED AND THUS ONLY A LIGHT PRECIP EVENT STILL
LOOKS ON TAP FOR TUE NIGHT FOR THE MAJORITY OF THE DVN CWA. THERMAL
PROFILES TUE EVENING ALONG AND NORTH OF A LINE FROM MT CARROLL IL...
TO CID AND SOUTHWEST OF IOWA CITY SUGGEST LIGHT SNOW AND SLEET IN
THESE AREAS TUE EVENING...AND ONLY FLURRIES ALONG AND NORTH OF THE
HWY 20 CORRIDOR. SNOW AND SLEET ACCUMS UNDER AN INCH TUE EVENING IN
THESE AREAS...BUT A CHANCE OF A NARROW SWATH OF 1-2 INCHES OF
SNOW ACCUM ON THE NORTHERN FRINGE OF RAIN/SLEET TRANSITION TO SNOW
BAND FROM WILLIAMSBURG TO CLINTON IA BY MID TUE EVENING. THEN IN-
WRAPPING MID LEVEL DRYING SHOULD SWITCH ALMOST ALL THE PRECIP TO
MAINLY DRIZZLE OR FREEZING DRIZZLE FROM MID EVENING THROUGH 12 AM-1
AM CST. AREAS OF TEMPORARY DENSE FOG POSSIBLE TOO BUT WILL LEAVE
OUT MENTION AT THIS POINT. THEN WITH THE APPROACH OF THE MID LEVEL
LOW AFTER MIDNIGHT...THE FCST SOUNDINGS SATURATE DEEPER AGAIN AND
SUPPORT A BAND OF SECONDARY DEF ZONE RAINS CLIPPING THE SOUTHEAST
THIRD OF THE CWA INTO EARLY WED MORNING WITH UP TO .3 OR .4 INCHES OF
RAIN POSSIBLE BY 8 AM CST WED. THE WESTERN FRINGE OF THIS DEF ZONE
RAIN MAY MIX WITH SNOW BY WED MORNING WITH LIGHT SLUSHY SNOW ACCUMS
UP TO AN INCH. FURTHER NORTH AND WEST OVER THE REST OF THE CWA...
LIGHT DRIZZLE OR FREEZING DRIZZLE DEPENDING ON THE SFC TEMPS WILL
LOOK TO TOP-DOWN COOL AND SATURATE INTO ALL LIGHT SNOW PARAMETERS
AFTER 1 AM WITH LIGHT ADDITIONAL SNOW ACCUMS POSSIBLE UP TO AN INCH
BY WED MORNING WHEN THE PRECIP WILL BE ON THE MOVE OUT OF THE LOCAL
FCST AREA. WILL STILL HAVE TO BE WARY OF SOME BANDED SNOWS OF AT
LEAST 1-2 INCHES AS THE UPPER LOW APPROACHES LATE TUE NIGHT IF
DYNAMICAL/TOP DOWN COOLING OCCURS QUICKER THAN CURRENTLY ANTICIPATED.
THERE STILL MAY BE A NEED FOR A WINTER WEATHER ADVISORY TUE NIGHT FOR
THE ROUNDS OF LIGHT FREEZING RAIN...FREEZING DRIZZLE...SNOW AND SLEET
MIX WITH AREAS ALONG AND NORTH OF I80 THE MOST LIKELY TARGET. THE
REST OF WED AND WED NIGHT SHOULD HAVE NO REAL WX MAKERS AND BE QUIET.
THURSDAY THROUGH FRIDAY...DEPENDING ON WHAT LIES IN THE WAKE OF THE
MID WEEK SYSTEM STREAM FLOW AND BAROCLINICITY-WISE...A RE-LOADING
SOUTHWESTERN CONUS TROF AND ACTIVE NORTHERN STREAM ACRS THE WEST
HALF OF THE CONUS HAVE ALL THE MEDIUM RANGE MODELS A FLUTTER THIS
PERIOD. MUCH UNCERTAINTY OF COURSE...BUT SIGNALS OF SOUTH-WESTERLIES
IN THE SOUTHERN STREAM REORGANIZING SOUTH AND SOUTHWEST OF THE
LOCAL AREA JUST SOUTH OF CONFLUENT FLOW MAY ALLOW SOME ELEVATED
FRONTOGENETICAL FORCING ALONG AND BEHIND A LLVL FRONT GETTING
ALIGNED PARALLEL TO THIS MEAN FLOW TO GENERATE SOME LIGHT SNOW OR
FLURRIES ACRS THE CWA EITHER LATE THU OR THU NIGHT INTO FRI
MORNING. AT THIS POINT WITH THE DRY LOOKING VERTICAL PROFILES...JUST
A DUSTING TO UNDER AN INCH WOULD ALL THAT WOULD BE POSSIBLE BY FRI
MORNING AND MAINLY FROM IOWA CITY TO FREEPORT IL AND NORTHWARD.
THE 12Z RUN UKMET...GEM AN GFS ARE EITHER DRY OR JUST HAVE FLURRIES
FOR THU NIGHT. LONGER RANGE SIGNALS SUGGEST PHASING ISSUES A PLENTY
AS THE DIGGING NORTHERN STREAM UPPER TROF OVER CENTRAL CANADA TRIES
TO INTERACT WITH THE SOUTHWEST PLAINS TROFFINESS. THE MAJORITY OF
THE LONGER RANGE MODELS HANDLE THIS PROCESS IN A WAY THAT ANY
SOUTHERN STREAM WX MAKER AND IT/S ASSOCIATED PRECIP REMAINS ALONG
OR SOUTH OF THE DVN CWA FROM FRI INTO SAT. BUT THE 12Z GFS MUCH
MORE OMINOUS AND DEVELOPED UPSTREAM. IT PHASES THE STREAMS IN A WAY
THAT A STORM SYSTEM WITH AT LEAST HIGHER END ADVISORY SNOWS/2-5+
INCHES IMPACTS THE ENTIRE CWA FRI NIGHT INTO SAT MORNING. WILL WATCH
FURTHER TRENDS OF COURSE WITH ADDITIONAL RUNS OVER THE NEXT 24-48
HRS. WILL GO WITH SEASONABLE TEMPS FOR THU THROUGH FRI FOR NOW.
SATURDAY THROUGH MONDAY...ENSEMBLES AND TELECONNECTIONS OVER THE
HOLIDAY WEEKEND SUGGEST SOME AO/ARCTIC OSCILLATION INFLUENCE AS
GENERAL L/W TROFFINESS TRIES TO ESTABLISH THIS PERIOD AND INTO EARLY
NEXT WEEK ACRS THE UPPER MIDWEST AND GRT LKS. THIS PERIOD ALSO LOOKS
GENERALLY DRY AFTER SAT WITH SOME RE-ENFORCING COOL SHOTS OUT OF
CANADA POSSIBLE FOR SEASONABLE OR SOMEWHAT BELOW TEMPS INTO NEXT
MONDAY. CAN/T RULE OUT SOME FLURRIES ON LEADING EDGES OF COOL DUMPS
OR WEAK WAVES EMBEDDED IN NORTHWESTERLY CYCLONIC FLOW...BUT WILL GO
MAINLY DRY FOR NOW. ..12..
&&
.AVIATION...
VFR WX IS GENERALLY EXPECTED THROUGH 03Z/20 WITH THE EXCEPTION OF
MVFR CIGS AT KDBQ. AFT 03Z/20 CONDITIONS WILL DETERIORATE AT KBRL
WITH MVFR CONDITIONS DVLPG WITH PRECIPITATION EXPECTED AFT 06Z/20
WHICH MAY INCLUDE PL. IFR CONDITIONS ARE POSSIBLE BEGINNING AROUND
12Z/20. AFT 12Z/20 CONDITIONS WILL DETERIORATE AT KCID/KMLI WITH MVFR
CONDITIONS DVLPG. KDBQ IS EXPECTED TO SEE MVFR CONDITIONS DVLPG ARND
18Z/20. ..08..
&&
.DVN WATCHES/WARNINGS/ADVISORIES...
IA...NONE.
IL...NONE.
MO...NONE.
&&
$$
08/12
AREA FORECAST DISCUSSION
NWS QUAD CITIES IA IL
1138 AM CST MON DEC 19 2011
.AVIATION...
DRY COLD FRONT HAS MOVED THROUGH ALL TAF SITES WHICH IS PULLING IN DRY
LOW LEVEL AIR TO THE AREA. A LAYER OF CLOUDS AROUND 2KFT AGL WILL
AFFECT KCID/KDBQ THROUGH 00Z/20. OTHERWISE...VFR WX IS EXPECTED
THROUGH 06Z/20. MVFR CONDITIONS AND PRECIP WL DVLP AT KBRL 06Z-
12Z/20 AND MAY GO TO IFR AFT 12Z/20. KCID/KMLI SHOULD SEE MVFR
CONDITIONS AND PRECIP DVLP ARND OR AFT 15Z/20 THAT MAY GO TO IFR
AFT 18Z/20.
..08..
&&
.PREV DISCUSSION... /ISSUED 1039 AM CST MON DEC 19 2011/
UPDATE...
MORNING UA ANALYSIS COMBINED WITH A 15Z SFC ANALYSIS SHOW PLENTY
OF DRY AIR MOVING SOUTH INTO THE CWFA. AS OF 15Z...THE SFC COLD
FRONT WAS INTO SOUTHERN WISCONSIN. IT RE-DEVELOPED AROUND KDBQ AND
EXTENDED SOUTHWEST TO NEAR KTOP. A PRE-FRONTAL TROF RAN FROM
SOUTHERN LAKE MICHIGAN TO AROUND KCDJ.
RUC TRENDS SHOW VERY HIGH CONDENSATION PRESSURE DEFICITS ACROSS
THE CWFA THROUGH 00Z IN THE LOW AND MID LEVELS. ON THE 290K AND
295K THETA SURFACES...THE CONDENSATION PRESSURE DEFICITS ARE EVEN
HIGHER WITH VERY LITTLE FORCING ACROSS THE AREA. FCST SOUNDINGS
FROM THE RUC IN THE FAR SOUTHERN CWFA ONLY SUGGEST A NARROW LAYER
OF MOISTURE AROUND 900MB WITH CONSIDERABLE DRY AIR ABOVE AND
SLIGHTLY DRIER AIR BELOW.
COMPRESSIONAL HEATING WITH THE TROF AND FRONT ARE RAISING
TEMPERATURES HIGHER THAN FCST AS WELL. THE CAA BEHIND THE FRONT IS
NOT OVERLY STRONG. HOWEVER...THE WEAK SUN STRENGTH COMBINED WITH
INCOMING CLOUDS SHOULD PREVENT MUCH OF AN ADDITIONAL RISE THIS
AFTERNOON. TEMPERATURES WILL LIKELY DO A SLOW FALL THROUGH THE
AFTERNOON IN THE NORTH AND NORTHWEST PARTS OF THE CWFA.
AN UPDATE TO THE FCST WILL BE AVAILABLE BY 1045 AM.
.08..
&&
.DVN WATCHES/WARNINGS/ADVISORIES...
IA...NONE.
IL...NONE.
MO...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS QUAD CITIES IA IL
1039 AM CST MON DEC 19 2011
.UPDATE...
MORNING UA ANALYSIS COMBINED WITH A 15Z SFC ANALYSIS SHOW PLENTY
OF DRY AIR MOVING SOUTH INTO THE CWFA. AS OF 15Z...THE SFC COLD
FRONT WAS INTO SOUTHERN WISCONSIN. IT RE-DEVELOPED AROUND KDBQ AND
EXTENDED SOUTHWEST TO NEAR KTOP. A PRE-FRONTAL TROF RAN FROM
SOUTHERN LAKE MICHIGAN TO AROUND KCDJ.
RUC TRENDS SHOW VERY HIGH CONDENSATION PRESSURE DEFICITS ACROSS
THE CWFA THROUGH 00Z IN THE LOW AND MID LEVELS. ON THE 290K AND
295K THETA SURFACES...THE CONDENSATION PRESSURE DEFICITS ARE EVEN
HIGHER WITH VERY LITTLE FORCING ACROSS THE AREA. FCST SOUNDINGS
FROM THE RUC IN THE FAR SOUTHERN CWFA ONLY SUGGEST A NARROW LAYER
OF MOISTURE AROUND 900MB WITH CONSIDERABLE DRY AIR ABOVE AND
SLIGHTLY DRIER AIR BELOW.
COMPRESSIONAL HEATING WITH THE TROF AND FRONT ARE RAISING
TEMPERATURES HIGHER THAN FCST AS WELL. THE CAA BEHIND THE FRONT IS
NOT OVERLY STRONG. HOWEVER...THE WEAK SUN STRENGTH COMBINED WITH
INCOMING CLOUDS SHOULD PREVENT MUCH OF AN ADDITIONAL RISE THIS
AFTERNOON. TEMPERATURES WILL LIKELY DO A SLOW FALL THROUGH THE
AFTERNOON IN THE NORTH AND NORTHWEST PARTS OF THE CWFA.
AN UPDATE TO THE FCST WILL BE AVAILABLE BY 1045 AM.
..08..
&&
.PREV DISCUSSION... /ISSUED 555 AM CST MON DEC 19 2011/
AVIATION...
THE COLD FRONT WILL MOVE THROUGH ALL TAF SITES SHIFTING WINDS TO THE
NORTHWEST BY EARLY AFTERNOON. VFR CONDITIONS ARE EXPECTED BOTH
AHEAD OF AND BEHIND THE FRONT FOR MUCH OF THE DAY. THERE WILL BE
SOME CIGS BASED AROUND 4KFT ALONG AND EAST OF THE MISSISSIPPI
RIVER THIS MORNING. BEHIND THE FRONT SOME CLOUDS BASED AROUND
2KFT MAY MOVE INTO THE KCID/KDBQ AREA BY LATE THIS AFTERNOON.
THESE CLOUDS WILL BE BREAKING UP AS THE REACH EAST CENTRAL
IOWA...SO THEY MAY ONLY RESULT IN A SCATTERED LAYER. VFR
CONDITIONS WILL REMAIN OVER KCID/KDBQ AREAS FOR THE OVERNIGHT
HOURS WITH SURFACE WINDS BECOMING NORTHEASTERLY. EXPECT
DETERIORATING CONDITIONS IN THE SOUTH INCLUDING KBRL AS RAIN
SPREADS IN FROM THE SOUTH LATE THIS AFTERNOON. A RAIN/SNOW/SLEET
MIX WITH MVFR CIGS/VSBYS IS EXPECTED THE REST OF THE NIGHT. KMLI
WILL BE ON THE NORTHERN FRINGE OF THE PRECIPITATION TONIGHT.
EXPECT CIGS/VSBYS REMAIN IN THE VFR CATEGORY WITH A LOW POTENTIAL
FOR SOME LIGHT SNOW OR SLEET ESPECIALLY AFTER 06Z.
PREV DISCUSSION... /ISSUED 419 AM CST MON DEC 19 2011/
SYNOPSIS...
SPLIT MID LEVEL FLOW CONTINUES TO DOMINATE THE CONUS THIS MORNING.
A NORTHERN STREAM S/W TROF WAS DROPPING SOUTHEAST THROUGH THE
NORTHERN ROCKIES WITH FLAT ZONAL FLOW EAST OF THE TROF ACROSS THE
REST OF THE NORTHERN TIER OF STATE. THE SOUTHERN STREAM CUTOFF LOW
WAS MOVING EAST ALONG THE AZ/MEXICAN BORDER. S/W RIDGING AHEAD OF
THE UPPER LOW EXTENDED FROM THE CENTRAL GULF COAST NORTHWEST THROUGH
THE CENTRAL PLAINS. AT THE SURFACE A COLD FRONT WAS LOCATED FROM
NORTHERN WI THROUGH SOUTHEAST MN AND NORTHWEST IA AT MIDNIGHT. NO
PRECIP WAS OCCURRING WITH THE BOUNDARY...BUT AN EXTENSIVE STRATUS
FIELD WAS LOCATED IN THE COLD AIR...BUT LAGGING THE SURFACE FRONT.
IN THE WARM SECTOR UNSEASONABLY MILD EARLY MORNING TEMPERATURES WERE
OCCURRING. AN AREA OF STRATUS WITH ITS WESTERN EDGE ALONG THE
MISSISSIPPI RIVER WAS CO-LOCATED WITH THE LOW LEVEL MOIST FEED.
TEMPERATURES UNDER THIS CLOUD DECK WERE STILL IN THE UPPER 40S EARLY
THIS MORNING WITH MID/UPPER 30S UNDER CLEAR SKIES WEST OF THE
RIVER.
SHORT TERM...TODAY AND TONIGHT...
SHORT RANGE MODELS WERE IN CLOSE AGREEMENT WITH THE OVERALL SYNOPTIC
PATTERN FOR TODAY AND TONIGHT. THE SURFACE COLD FRONT IS PROGGED TO
MOVE THROUGH THE CWFA TODAY AND SHOULD EXIT THE SOUTHERN COUNTIES BY
MID AFTERNOON. THE SOUTHERN STREAM CUTOFF UPPER LOW IS PROGGED TO
BE OVER SOUTHERN NM THIS MORNING AND IS EXPECTED TO LIFT NORTHEAST
INTO TX/OK PANHANDLES BY TUESDAY MORNING. MODEL QPF FIELDS ARE
SIMILAR IN BREAKING OUT/EXPANDING PRECIPITATION OVER THE SOUTHERN
PLAINS THIS MORNING AS GULF MOISTURE WORKS NORTH AND INTERACTS WITH
THE UPPER SYSTEM. THE PRECIPITATION IS PROGGED TO SPREAD NORTHEAST
UNTIL IT ENCOUNTERS DRY LOW LEVEL AIR OVER SOUTHERN IA CAUSING IT TO
STALL OVERNIGHT.
FOR TODAY THE BIG CHALLENGE WILL BE THE COLD AIR STRATUS OVER MN/SD
EARLY THIS MORNING. MODEL LOW RH PROGS SHOW THE STRATUS BREAKING UP
AS IT MOVES SOUTHEAST. CONCEPTUALLY THIS MAKES SENSE AS WINDS IN
THE CLOUD BEARING LAYER OVER SD/NE BECOME MORE NORTHEASTERLY THIS
MORNING AS LOW PRESSURE DEVELOPS OVER THE SOUTHERN PLAINS. WINDS
OVER THE GREAT LAKES REMAIN NORTHERLY CAUSING DIFFLUENT POST FRONTAL FLOW
OVER IA. THIS SHOULD KEEP THE BULK OF THE STRATUS FROM REACHING THE
CWFA...SO PARTLY TO MOSTLY SUNNY SKIES ARE EXPECTED OVER THE WESTERN
CWFA THIS MORNING WITH CLEARING OCCURRING OVER THE NORTHEAST AS THE
WARM SECTOR STRATUS IS PUSHED EAST WITH THE COLD FRONT. MID/HIGH
CLOUDS SHOULD SPREAD BACK INTO THE SOUTHERN CWFA LATE THIS MORNING
AND THIS AFTERNOON AHEAD OF THE SOUTHERN STREAM UPPER LOW. LESS
CLOUDS TODAY SUPPORTS SLIGHTLY WARMER TEMPERATURES ESPECIALLY IN THE
NW WHERE SUNSHINE SHOULD OFFSET SOME OF THE COLD AIR ADVECTION.
SOME LOW CHANCE POPS WERE MAINTAINED IN THE FAR SOUTH LATE THIS
MORNING AND THIS AFTERNOON. TEMPERATURES INITIALLY SUPPORT ALL
RAIN. IF THE RAIN MAKES AS FAR NORTH AS HIGHWAY 34...THEN SOME SLEET
COULD MIX IN WITH THERMAL PROFILES SHOWING SOME REFREEZING IS
POSSIBLE NEAR THE SURFACE.
TONIGHT PRECIPITATION CHANCES WILL INCREASE OVER THE SOUTH WITH THE
NORTHERN EXTENT OF THE PRECIPITATION EXPECTED TO BE NEAR INTERSTATE
80. WILL GO WITH CATEGORICAL POPS IN THE FAR SOUTH TAPERING OFF TO
SLIGHTS NEAR THE INTERSTATE. A MIX WAS ALSO MENTIONED ACROSS THE
SOUTH TONIGHT. THERMAL PROFILES SUPPORT A RAIN/SNOW MIX WITH A LOW
POTENTIAL FOR SLEET. FURTHER NORTH IT LOOKS MORE LIKE A SNOW/SLEET
MIX. FREEZING RAIN WAS NOT MENTIONED SINCE SURFACE TEMPERATURES IN
THE FAR SOUTH ARE EXPECTED TO STAY JUST ABOVE FREEZING.
PRECIPITATION AMOUNTS BY TUESDAY MORNING ARE EXPECTED TO BE LESS
THAN A HALF INCH. THERE MAY BE SOME ACCUMULATION OF SNOW SOUTH
OF HIGHWAY 34 BUT WITH THE EXPECTED MIXED PRECIPITATION...SNOW
AMOUNTS WERE KEPT UNDER ONE HALF INCH. ..DLF..
LONG TERM...TUESDAY THROUGH SUNDAY...
TUESDAY THROUGH WEDNESDAY...THE MAIN FORECAST CONCERNS ARE WITH THE
DETAILS OF THE SURFACE LOW TRACK AND ASSOCIATED PRECIPITATION
TYPE/S. THE FORECAST MODELS ARE IN GOOD OVERALL AGREEMENT...ALTHOUGH
THERE ARE SOME SLIGHT DIFFERENCES IN THE THERMAL AND MOISTURE
DETAILS WHICH MAKE ALL THE DIFFERENCE IN WHAT PRECIPITATION TYPE/S
WILL OCCUR.
AS THE CLOSED UPPER LOW SLOWLY EJECTS NORTHEAST...THE SURFACE LOW IS
FORECAST TO TRACK ACROSS SOUTHEAST MISSOURI AND CENTRAL ILLINOIS
ON TUESDAY. ALTHOUGH THE BULK OF PRECIPITATION FROM THIS SYSTEM
MAY FALL BY TUESDAY MORNING...GENERALLY LIGHT PRECIPITATION IS
EXPECTED TO AFFECT PORTIONS OF THE FORECAST AREA THROUGH AT LEAST
TUESDAY NIGHT. THE PRECIPITATION TO START THE DAY TUESDAY WILL BE
ASSOCIATED WITH THE WARM MOIST CONVEYOR REGION ON THE NORTHWEST SIDE
OF THE SURFACE LOW TRACK. FORECAST THERMAL PROFILES ARE NOT CLEAR
CUT...AS TEMPERATURES HOVER NEAR THE CRITICAL THRESHOLDS FOR
FREEZING/FROZEN PRECIPITATION. MIXED PRECIPITATION IN THE FORM OF
SNOW AND/OR SLEET IS LIKELY THROUGH THE MORNING TUESDAY...WITH THE
SOUTHERN THIRD OR SO OF THE FORECAST AREA THE MOST LIKELY TO SEE
RAIN AS ONE OF THE PRECIPITATION TYPES. AS THE DEEPER MOISTURE WITH
THIS SYSTEM IS FORECAST TO BE SHUNTED TO THE SOUTHEAST...THE THERMAL
PROFILES SUGGEST THERE MAY BE LIMITED MOISTURE IN THE ICE GROWTH
LAYER...ESPECIALLY AS THE DAY PROGRESSES ON TUESDAY. THIS WOULD MEAN
THAT THE DOMINANT PRECIPITATION TYPE MAY BE RAIN OR DRIZZLE. SURFACE
TEMPERATURES ARE EXPECTED TO BE ABOVE FREEZING FOR MUCH OF THE
DAY...OTHERWISE WHERE TEMPERATURES MIGHT BE BELOW FREEZING FOR A
TIME...THE RAIN OR DRIZZLE COULD BECOME FREEZING RAIN OR DRIZZLE.
THIS MAY BE MORE OF A CONCERN AS TEMPERATURES DIURNALLY FALL TUESDAY
NIGHT...AT WHICH TIME THE AREA IS FORECAST TO BE AFFECTED BY
PRECIPITATION ASSOCIATED WITH THE SYSTEMS DEFORMATION ZONE.
ONE POSITIVE IN ALL OF THESE QUESTIONS ABOUT PRECIPITATION TYPE IS
THAT PRECIPITATION AMOUNTS LOOK TO BE ON THE LIGHTER SIDE. LIQUID
PRECIPITATION TOTALS FROM DAYBREAK TUESDAY THROUGH WEDNESDAY MORNING
ARE FORECAST TO BE UP TO A QUARTER OF AN INCH ACROSS THE SOUTHERN
FORECAST AREA AND TAPER OFF TO AROUND A TENTH OF AN INCH TOWARD THE
NORTHERN FORECAST SECTIONS.
AN ACTIVE WEATHER PATTERN IS FORECAST TO CONTINUE BEYOND
WEDNESDAY...AS SHORTWAVES COME ACROSS FROM THE PACIFIC NORTHWEST.
THE AMOUNT OF PHASING BEFORE THE SHORTWAVES EJECT ACROSS THE CONUS
CONTINUES TO BE THE CHALLENGE. GENERALLY SPEAKING...NEAR TO SLIGHTLY
ABOVE NORMAL TEMPERATURES ARE EXPECTED TO CONTINUE THROUGH THE WEEK.
LOW PRECIPITATION CHANCES WERE CARRIED FROM FRIDAY INTO SATURDAY AS
ONE OF THE UPPER WAVES IS FORECAST TO KICK OUT ACROSS THE CENTRAL
CONUS. CONFIDENCE IN THIS PRECIPITATION SCENARIO REMAINS LOW FOR
NOW. ..STOFLET..
&&
.DVN WATCHES/WARNINGS/ADVISORIES...
IA...NONE.
IL...NONE.
MO...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS TOPEKA KS
358 PM CST MON DEC 19 2011
.DISCUSSION...
THE FOCUS OF THIS FORECAST REMAINS ON THE POTENT STORM SYSTEM WHICH
WILL MOVE OFF THE HIGH PLAINS AND BRING RAIN AND SNOW TO ALL OF
NORTHEAST AND EAST CENTRAL KANSAS TONIGHT AND TOMORROW.
20Z WATER VAPOR IMAGERY AND ASSOCIATED RUC ANALYSIS SHOWING THE 500
MB TROUGH MAKING A NORTHEAST TURN AS IT TAKES ON A NEGATIVE TILT
OVER FAR WESTERN TEXAS. STRONG ISENTROPIC LIFT CAUSING A WIDE SHIELD
OF PRECIPITATION MAINLY IN THE FORM OF RAIN TO MOVE NORTHWARD ACROSS
THE AREA. SOME ELEVATED INSTABILITY HAS ALLOWED FOR SOME WEAK
CONVECTION WITHIN THE AREA OF PRECIP ALLOWING FOR A FEW RUMBLES OF
THUNDER. WITH WARM LOW LEVEL TEMPERATURES ACROSS FAR EASTERN KANSAS
THE PRECIPITATION HAS FALLEN AS RAIN THROUGHOUT THE DAY. FURTHER TO
THE WEST COOLER AIR IN THE LOWER TO MID LEVELS HAS FACILITATED A
GRADUAL CHANGE OVER TO A MIX OF RAIN AND SNOW WITH SOME SLEET.
ACROSS CENTRAL AND SOUTHWEST KANSAS WHERE THE COLD AIR IS EVEN
DEEPER PRECIP HAS CHANGED COMPLETELY OVER TO SNOW. THE AREA WITH THE
BIGGEST CONCERN FOR THIS SYSTEM WILL BE ACROSS CENTRAL AND NORTH
CENTRAL KANSAS WHERE SNOW AMOUNTS COULD BE THE HIGHEST. BEST
FRONTOGENETICAL LIFT AND ASSOCIATED HIGHEST OMEGA LOOKS TO PERSIST
ACROSS THE AREA BETWEEN 00Z AND 12Z TONIGHT...AND THIS WILL LIKELY
BRING THE HEAVIEST SNOW...ESPECIALLY TO AREAS OF CENTRAL KANSAS.
GOOD LIFT THROUGH THE -8 TO -14 C DENDRITIC GROWTH LAYER WILL LIKELY
KEEP ALL PRECIP WEST AND NORTH OF A HIAWATHA TO COUNCIL GROVE LINE.
SNOW COULD RAPIDLY INCREASE WITH SNOW RATES APPROACHING 3 TO 5
INCHES OVER A 6 TO 10 HOUR PERIOD ACROSS THAT AREA. COMPLICATING THE
CONDITIONS WILL BE STRONG WINDS ACROSS CENTRAL KANSAS
OVERNIGHT...LEADING TO REDUCED VISIBILITIES AND DANGEROUS TRAVEL
CONDITIONS...ESPECIALLY ALONG INTERSTATE 70. VERY TRICKY PRECIP TYPE
FORECAST FOR AREAS ALONG AND EAST OF THE KANSAS TURNPIKE. FORECAST
SOUNDINGS INDICATE ICE CRYSTALS INTRODUCED INTO THE ATMOSPHERIC
COLUMN...BUT WARMER 850 MB TEMPS COULD TEMPER THE ABILITY OF SNOW TO
REACH THE SURFACE. HOWEVER WITH REAL TIME TEMPS RUNNING A BIT COOLER
THAN MODEL TEMPS...MAY NEED TO CALIBRATE MODELS WITH REAL TIME INFO
AND LEAN TOWARD A SLIGHTLY COOLER SOLUTION...FOR PRECIP TYPES AND
SNOW AMOUNTS ACROSS THE EASTERN COUNTIES. SHOULD PRECIP BE ABLE TO
CHANGE OVER TO SNOW BY 01 TO 03Z EAST OF THE AFOREMENTIONED HIAWATHA
TO COUNCIL GROVE LINE...MAY NEED TO BUMP UP SNOW
AMOUNTS...ESPECIALLY FOR THE TOPEKA AREA. AROUND 12Z TUESDAY MORNING
DRY MID LEVEL AIR WILL PUSH INTO THE AREA WHICH WILL REMOVE ICE
CRYSTALS FROM THE COLUMN FOR A FEW HOURS TUESDAY MORNING. DURING
THIS TIME EXPECT PRECIP TO GO FROM A LIGHT SNOW TO A LIGHT DRIZZLE
OR FREEZING DRIZZLE ACROSS AREAS WHERE TEMPS ARE BELOW FREEZING. BY
LATE TUESDAY AFTERNOON THE MID LEVEL TROWAL WILL SET UP NEAR THE
INTERSTATE 70 CORRIDOR WHICH COULD BRING ANOTHER ROUND OF LIGHT SNOW
FOR TUESDAY AFTERNOON AS THE ATMOSPHERIC COLUMN SHOULD BE COOL
ENOUGH ACROSS THE ENTIRE FORECAST AREA.
WILL NOT MAKE ANY MAJOR CHANGES TO THE ONGOING WARNING/ADVISORY
LOCATIONS AS COUNTIES CURRENTLY UNDER THE WINTER STORM WARNING ARE
STILL ON TRACK TO ACCUMULATE 6 TO 8 INCHES OF SNOW. THE COUNTIES
FURTHEST NORTH AND EAST CONTAIN LESSER CONFIDENCE IN REACHING THE 6
TO 8 INCH RANGE...BUT COUNTIES ALONG INTERSTATE 70 AND WEST OF THE
KANSAS TURNPIKE SHOULD EXPECT AT LEAST 4 TO 6 INCHES OF SNOW...WITH
HIGHER AMOUNTS ACROSS CENTRAL KANSAS. ALSO STRONG WINDS ALONG
INTERSTATE 70 WILL COMPLICATE TRAVEL CONDITIONS AS THEY WILL
COINCIDE WITH THE HEAVY SNOW OVERNIGHT TO BRING LOWERED VISIBILITY
AND DANGEROUS TRAVEL CONDITIONS.
EXPECT LIGHT SNOW TO GRADUALLY COME TO AN END BY EARLY WEDNESDAY
MORNING AS THE UPPER TROUGH EXITS COMPLETELY OUT OF THE AREA WITH
CLEARING SKIES AND SEASONABLE TEMPS.
ANOTHER SYSTEM SWINGS INTO THE PLAINS THURSDAY INTO FRIDAY BUT
WITH A NORTHERLY TRAJECTORY AND MORE LIMITED MOISTURE WILL CARRY
CHANCE TO SLIGHT CHANCE POPS AT THIS TIME. CONDITIONS CLEAR OUT
FOR SATURDAY WITH ANOTHER PUSH OF COLDER AIR SATURDAY NIGHT INTO
SUNDAY.
&&
.AVIATION...
EXPECT MVFR CONDITIONS OVER TERMINALS THROUGH AT LEAST 0Z AS
RADAR SHOWS WIDESPREAD RAINFALL TRACKING NORTHWARD OVER TERMINALS.
NORTHERLY WINDS INCREASE BEHIND PASSAGE OF COLD FRONT FROM 10 TO
20 KTS SUSTAINED THROUGH FORECAST PERIOD. AS COLDER AIR FILTERS
SOUTHWARD...EXPECT A TRANSITION TO IFR AFTER 00Z AT KMHK AND 05Z
AT KTOP/KFOE AS RAIN TRANSITIONS TO SNOW AND VISIBILITIES/CIGS
LOWER. THE HEAVIEST SNOW IS FORECAST TO OCCUR AROUND 03Z AND
THEREAFTER AT KMHK WHERE CONDITIONS MAY REACH LIFR IN THE HEAVIER
SNOW BANDS. KTOP AND KFOE MAY SEE A MIXTURE OF LIGHT FREEZING
DRIZZLE WITH THE LIGHT SNOW TUESDAY MORNING.
BOWEN
&&
.TOP WATCHES/WARNINGS/ADVISORIES...
WINTER STORM WARNING UNTIL 6 PM CST TUESDAY FOR KSZ009>011-
020>023-034>036.
WINTER WEATHER ADVISORY UNTIL 6 PM CST TUESDAY FOR KSZ008-012-
024-026-037>039.
WINTER WEATHER ADVISORY FROM MIDNIGHT TONIGHT TO 6 PM CST
TUESDAY FOR KSZ040-054-055.
&&
$$
AREA FORECAST DISCUSSION
NWS DODGE CITY KS
320 PM CST MON DEC 19 2011
.SYNOPSIS...
THE OVERALL SYNOPSIS FROM THE 12Z...250MB CHART SHOWED A 80-KNOT
JET STREAK OF WIND FROM SOUTHWEST TEXAS THROUGH SOUTHWEST KANSAS
TO SOUTHERN IOWA. A STRONGER 110KT NORTHWEST JET WAS ENTERING BAHA
CALIFORNIA (W. MEXICO), WHILE A 120-KNOT JET STRETCHED FROM
NORTHERN MINNESOTA TO SOUTHWEST QUEBEC. THE 500MB CHART AT 12Z HAD
A LARGE UPPER LOW PRESSURE SYSTEM OVER EXTREME WESTERN TEXAS, WITH
MOISTURE FLOWING NORTHEASTWARD INTO KANSAS. THE 500MB TEMPERATURE
AT DDC WAS AT 17C. THE 700 MB CHART LOOKED SIMILAR TO THE 500MB
CHART PATTERN, BUT WITH THE H7 LOW PRESSURE OVER SOUTH CENTRAL NEW
MEXICO. A COLD FRONT WAS EVIDENT AT 12Z AT THE 850MB LEVEL ACROSS
NORTH CENTRAL KANSAS, WITH LBF AT -04C AND DDC AT +10C.
&&
.DISCUSSION...
DAYS 1-2...
THE UPPER STORM SYSTEM MOVING ACROSS NEW MEXICO AND TEXAS, AND
INTO NORTHERN OKLAHOMA, WAS BRINGING WINTER-LIKE WEATHER TO MOST
OF SOUTHWESTERN KANSAS THIS AFTERNOON. THERE WAS A BAND OF RAIN,
SOME MODERATE, THAT MOVED NORTH FROM FROM OKLAHOMA MORNING LAID
DOWN 0.02 TO 0.50 INCH OF RAIN ACROSS MUCH OF OUR SOUTHERN CWA.
THIS SOAKED UPPER LAYER OF SURFACE GROUND WILL DELAY TO ONSET OF
ACCUMULATING SNOW, BUT SNOW RATES OF .5 TO 1.0-INCH PER HOUR AT
TIMES WILL LEAD TO A QUICK ACCUMULATION. FURTHERMORE, PER THE
FORECAST SOUNDINGS FROM THE NAM AND RUC MODELS BOTH SHOWED A WARM
ELEVATED LAYER OF +2 DEGREES, INDICATING THERE MAY BE SOME SLEET
OR LIGHT FREEZING RAIN BEFORE THE EASTERN PART OF THE CWA CHANGES
TO ALL SNOW, SO WILL MENTION THAT. A SURFACE COLD FRONT WAS
WORKING SOUTH THROUGH THE CWA TODAY, AND CLEARED THE SOUTHEAST
PART OF OUR FORECAST AREA BETWEEN 20 AND 21Z. WHERE THE
OVERRIDING COLD AIR WILL MEET THE BEST LIFT OVER THE ELEVATED
FRONT IS WHERE A HEAVY BAND OF SNOW SHOULD SET UP...FROM
APPROXIMATELY LAKIN TO GARDEN CITY TO NESS CITY...WHERE 10 TO 11
INCHES OF SNOW IS POSSIBLE BY TUESDAY AFTERNOON. SOUTHEAST OF THAT
ZONE, IN THE LIBERAL TO DODGE CITY TO KINSLEY TO SAINT JOHN ZONE...I
STILL THINK THERE COULD BE SOME BANDS OF HEAVY SNOW TONIGHT...WITH
LESS DURATION THAN NORTH OF THERE, AND 5 TO 8 INCHES OF SNOW IS
EXPECTED THERE BY TUESDAY AFTERNOON. IN BOTH THESE ZONES...STRONG
NORTH WINDS OF 20 TO 35 MPH WITH GUSTS TO NEAR 45 MPH WILL COMBINE
WITH THE SNOW TO CREATE LOW VISIBILITIES IN BLOWING AND DRIFTING
SNOW. WITH A FEW AREAS IN OUR EXTREME WEST SUCH AS TRB AND 3K3
ALREADY REPORTING M1/4SM +SN...THINK THIS COLD AIR AND STRONG
WINDS WILL WRAP TO THE EAST TONIGHT. THEREFORE, THE BLIZZARD
WARNING WILL CONTINUE THROUGH NOON TUESDAY, NORTHWEST OF A LINE
FROM COLDWATER TO PRATT. A WINTER WEATHER ADVISORY FOR 3 TO 5
INCHES OF SNOW AND BLOWING SNOW WILL ALSO CONTINUE THROUGH NOON
TUESDAY FOR PRATT, BARBER AND COMANCHE COUNTIES.
AS FOR TEMPS, THINK OVERNIGHT THAT LOWER DEW POINTS WILL BE
FILTERING IN FROM THE NORTH ON THE STRONG FLOW. STAYED PRETTY
CLOSE TO THE PREVIOUS FORECAST OF MIN T`S FROM AROUND 17F IN EHA
TO 23F IN P28. TOMORROW WILL SEE THICK CLOUDS AROUND ALONG WITH
EARLY SNOW. THE TEMPERATURE WILL NOT RISE MUCH AND SHOULD TOP OUT
IN THE 27F TO 30F DEGREE RANGE. CLOUDS WILL CLEAR OUT FROM WEST TO
EAST TUESDAY EVENING, AND WITH FRESH SNOW COVER EXPECTED AND LIGHT
WEST WINDS, THE TEMPERATURE SHOULD PLUMMET. LOWS TUESDAY NIGHT
WILL BE QUITE COLD, RANGING FROM A VERY COLD 5F IN EHA TO 14F IN
P28. WEDNESDAY, WE WILL STILL BE IN THE GRIP OF COLD ARCTIC AIR
CENTERED TO OUR NORTHEAST, BUT NOT MUCH WARMER THAN TUESDAY IN
MOST SPOTS. HAVE WENT WITH A MAX T FORECAST FOR WEDNESDAY IN THE
27F DEGREE RANGE NEAR LBL, EHA, GCK AND DDC, RANGING UP TO 33F AT P28.
DAYS 3-7...
A NORTHERN BRANCH SHORTWAVE TROUGH WILL DIG TO NEAR THE FOUR CORNERS
ON THURSDAY WITH SOME LIGHT SNOW EXPECTED MOSTLY IN THE AFTERNOON
ACROSS WESTERN KANSAS. THE TROUGH THEN WILL MOVE INTO THE PLAINS ON
FRIDAY WITH LIGHT SNOW ENDING FROM WEST TO EAST ON FRIDAY MORNING.
EXPECT LESS THAN AN INCH ACCUMULATION. ANOTHER LONGER WAVE TROUGH
WILL MOVE ACROSS THE CENTRAL CONUS ON SUNDAY WITH MAINLY DRY
CONDITIONS AND LESS MOISTURE TO WORK WITH. THE GFS AND NEW ECMWF ARE
DIFFERENT WITH ONE SHOWING A SHORTWAVE RIDGE AND THE OTHER A
SHORTWAVE TROUGH BUT LOOKS TO DRY FOR ANY PRECIPITATION.
A COLD FRONT WILL MOVE INTO THE CENTRAL PLAINS WITH HIGH PRESSURE
AND LOWS IN THE TEENS TO LOW 20S ON THURSDAY MORNING AND HIGHS FROM
THE UPPER 20S NORTH TO AROUND 34 SOUTHEAST FA ON THURSDAY. A RIDGE
OF COLD HIGH PRESSURE MOVES INTO THE PLAINS ON FRIDAY WITH LOWS IN
THE TEENS AND HIGHS ONLY IN THE MID 20S. SATURDAY MORNING LOOKS THE
COLDEST WITH LIGHT WINDS AND LOWS IN THE SINGLE DIGITS. FOR SATURDAY
HIGHS SHOULD BE AROUND 30 TO 35. ON CHRISTMAS DAY SUNDAY MORNING
LOWS WILL BE MAINLY IN THE TEENS AND HIGHS AROUND 30 TO 35 WITH
MOSTLY CLEAR SKIES. ON MONDAY MORNING LOWS WILL BE COLD AGAIN WITH
CLEAR SKIES AROUND 10 TO 15 DEGREES AND HIGHS MONDAY WITH WARMING
SOUTHWEST WINDS AND HIGHS FROM THE MID 30S TO LOWER 40S.
&&
.AVIATION...
FOR THE 18Z TAF ISSUANCE...
PRIMARILY IFR CONDITIONS WILL PREVAIL AT ALL TAF SITES THROUGH
TONIGHT AS LIGHT TO MODERATE RAIN CONTINUES TO SPREAD NORTH
ACROSS WESTERN KANSAS. RAIN WILL SWITCH OVER TO SNOW TONIGHT AT
ALL TAF SITES WHILE CIGS LOWER. STRONG NORTH TO NORTHEASTERLY
WINDS DEVELOPING BEHIND THE COLD FRONT WILL CAUSE BLOWING SNOW
CONDITIONS OVERNIGHT RESTRICTING VISIBILITIES THROUGH TUESDAY
MORNING. AS A RESULT, EXPECT IFR CIGS/VSBYS DURING PERIODS OF
HEAVIER SNOW AND BLOWING SNOW.
&&
.PRELIMINARY POINT TEMPS/POPS...
DDC 20 27 9 27 / 100 80 0 0
GCK 19 27 6 27 / 100 70 0 0
EHA 17 28 5 27 / 100 60 0 0
LBL 19 28 6 27 / 100 60 0 0
HYS 20 27 6 28 / 100 100 0 0
P28 23 30 14 33 / 100 90 10 0
&&
.DDC WATCHES/WARNINGS/ADVISORIES...
BLIZZARD WARNING UNTIL NOON CST /11 AM MST/ TUESDAY FOR KSZ030-
031-043>046-061>066-074>080-084>088.
WINTER WEATHER ADVISORY UNTIL NOON CST TUESDAY FOR KSZ081-089-
090.
&&
$$
FN12/07/35
AREA FORECAST DISCUSSION
NWS PITTSBURGH PA
1141 AM EST MON DEC 19 2011
.SYNOPSIS...
A COLD FRONT ACROSS LAKE MICHIGAN WILL PUSH INTO THE OHIO VALLEY
AND BECOME STATIONARY TONIGHT AND TUESDAY...BRINGING A MIXTURE OF
RAIN AND SNOW. LOW PRESSURE MOVING ALONG THIS BOUNDARY WILL BRING
RAIN TUESDAY NIGHT AND WEDNESDAY.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
UPDATE FOR THE AFTERNOON TO AGAIN MOVES TEMPERATURES UP MAINLY IN
EASTERN OHIO. ONLY MINOR CHANGES TO REMAINDER OF THIS AFTERNOON.
A FRONTAL BOUNDARY CROSSING THE GREAT LAKES WILL INCREASE CLOUDS
AND RAIN CHANCES THROUGH THE EVENING. SOUTHWEST FLOW WILL PUSH
AFTERNOON TEMPERATURES INTO THE 40S WITH GUSTY SOUTHWEST WINDS.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH WEDNESDAY/...
LATEST MODEL RUNS CONTINUE TO SHOW SURFACE BOUNDARY BECOMING
STATIONARY ACROSS THE SOUTHERN HALF OF THE FORECAST AREA LATE
TONIGHT. TEMPERATURE PROFILES FROM BUFKIT STILL SUGGEST THAT
MUCH OF THE REGION MAINLY NORTH OF THE MASON-DIXON LINE WILL HAVE
A RAIN/SNOW MIXTURE LATE TONIGHT INTO EARLY TUESDAY MORNING. QPF
AMOUNTS WILL BE LIGHT THROUGH TUESDAY. AREAS NORTH OF PITTSBURGH
TOWARD THE I-80 CORRIDOR WILL LIKELY CHANGE TO ALL SNOW MONDAY
NIGHT BUT ANY ACCUMULATION WILL BE LESS THAN AN INCH.
PRECIPITATION WILL CHANGE TO ALL RAIN BY TUESDAY AFTERNOON AS
TEMPERATURES RISE INTO THE UPPER 30S TO MID 40S.
A SHORT WAVE TROUGH WILL MOVE NORTHEAST FROM THE SOUTHERN PLAINS
WITH ITS ASSOCIATED SURFACE LOW TRACKING ACROSS THE OHIO VALLEY
WEDNESDAY. THIS SYSTEM WILL BRING PERIODS OF RAIN TUESDAY NIGHT
THROUGH LATE WEDNESDAY.
&&
.LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/...
WEAK SURFACE RIDGE WILL GIVE A GENERALLY DRY FORECAST THURSDAY. A
WEAK DISTURBANCE WILL BRING THE CHANCE FOR SHOWERS FRIDAY WITH
ABOVE NORMAL TEMPERATURES FOLLOWED BY HIGH PRESSURE AND SEASONABLE
TEMPERATURES SATURDAY. A COLD FRONT WILL BRING A CHANCE FOR RAIN
OR SNOW SHOWERS CHRISTMAS DAY. OVERALL LONG TERM FORECAST WAS A
MODIFIED VERSION OF THE HPC GRIDS.
&&
.AVIATION /18Z MONDAY THROUGH SATURDAY/...
NOT ALOT TO CHANGE FOR THIS TAF ISSUANCE AS MODEL BUFKIT PROFILES
AND RUC DATA CONTINUE TO SUGGEST WIND SHEAR ALOFT OVERNIGHT.
MAINTAINED WIND SHEAR OF WS010/23040KT THROUGH 16Z AS VERTICAL
MIXING BEGINS TO TAKE PLACE OUT AHEAD OF THE BOUNDARY PROGGED TO
BRING PRECIP TO ALL TERMINALS STARTING AROUND 19Z. SURFACE WINDS
WILL BECOME SOUTHWEST 10-15 KTS WITH GUSTS TO 20-25 KTS BY MIDDAY
MONDAY. CURRENT LAMP AND MAV GUIDANCE SUGGESTS RESTRICTIONS WILL
START OUT AT MVFR AS THE COLD FRONT DROPS SOUTHEASTWARD.
OUTLOOK...MONDAY NIGHT THROUGH FRIDAY...
STALLING COLD FRONTAL PRECIPITATION BAND WILL CAUSE FREQUENT IFR
PERIODS MONDAY NIGHT INTO WEDNESDAY. ENSUING WINTRY MIX MAY CAUSE
ADDED THE AVIATION HAZARD OF LOW LEVEL ICING TUESDAY. COLD POOL
STRATOCUMULUS MAY PROVIDE LINGERING RESTRICTIONS, MAINLY IN THE
MVFR RANGE THURSDAY. A NORTHEAST MOVING LOW PRESSURE SYSTEM MAY
PROVIDE MIXED PRECIPITATION AND IFR RESTRICTIONS FRIDAY.
&&
.PBZ WATCHES/WARNINGS/ADVISORIES...
MD...NONE.
OH...NONE.
PA...NONE.
WV...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
107 PM EST MON DEC 19 2011
UPDATED AVIATION DISCUSSION FOR THE 18Z TAFS
.DISCUSSION /TODAY THROUGH SUNDAY/... ISSUED AT 407 AM EST
997MB LOW PRESSURE SYSTEM LOCATED OVER EASTERN ONTARIO WILL CONTINUE
E INTO SRN QUEBEC THIS MORNING. COLD FRONT CURRENTLY SWEEPING
THROUGH CNTRL/ERN UPPER MI...WITH ONLY SCT CLOUDS ASSOCIATED WITH
IT/S PASSING. BEHIND THE FRONT...A LARGE AREA OF LOW CLOUDS OVER NRN
MN...SW ONTARIO AND MANITOBA WOULD INDICATE THAT MOISTURE MAY BE
BETTER THAN INDICATED BY THE 00Z NAM. 00Z GFS AND LATEST RUC RUNS
SEEM TO BE DOING A LITTLE BETTER ON PICKING UP THE LOW CLOUDS AND
WILL FOLLOW THAT FOR THE TODAY FORECAST /WHICH IS A LITTLE MORE
PESSIMISTIC/.
COLD AIR STILL LAGGING BEHIND THE FRONT...AND WITH THE AREA OF LOW
CLOUDS CURRENTLY WORKING INTO WRN UPPER MI...EXPECT SOME PCPN TO
START OVER THE NEXT COUPLE OF HOURS OVER THE UPSLOPE HIGHER TERRAIN.
H850-700 DRY AIR AND SUBSIDENCE WILL HELP KEEP INVERSION HEIGHTS AT
3KFT. DRY NEAR SFC AIR WILL KEEP CLOUD DEPTHS LIMITED /ONLY AROUND
1.5-2KFT/ SO HAVE LIMITED CONF ON MUCH PCPN OCCURRING. THIS COULD
CREATE SOME P-TYPE ISSUES INITIALLY...AS BUFKIT SOUNDINGS SHOW CLOUD
TEMPS ARE ONLY IN THE -4 TO -7C RANGE...LIMITING ICE CRYSTALS.
SHOULD BE A QUICK TRANSITION FROM W TO E THROUGH THE EARLY MORNING
HOURS WITH THE H850 TEMPS FALLING TO -11C BY 15Z. THEREFORE...WILL
CONTINUE MENTION OF DZ/FZDZ THROUGH 12Z OVER THE W AND JUST DZ
THROUGH 15Z OVER THE E DUE TO WARMER SFC TEMPS. THE COLDER H850
TEMPS WILL LIKELY LEAD TO SOME LIGHT LES DEVELOPMENT THIS
MORNING...BUT INVERSION HEIGHTS WILL LIMIT INTENSITY. WITH THE
LONGER FETCH...THINK THE LES WILL CONTINUE THROUGH THE AFTN EVEN
THOUGH THE LOWER INVERSION HEIGHTS MAY END UP LEADING TO MAINLY
CLOUDS. OTHERWISE...TRANSITIONED TO MORE OF A -SHSN/FLURRIES IN THE
AFTN OVER THE W BEFORE DECREASING CLOUDS LATE IN THE AFTN DUE TO THE
WARMING H850 TEMPS AND DRIER AIR FINALLY ARRIVING WITH THE
APPROACHING SFC RIDGE.
HIGH PRESSURE RIDGE SLIDES OVER THE AREA TONIGHT...BRINGING AN END
TO THE LES OVER THE E AND THE LK CLOUDS OVER THE REST OF THE AREA.
WITH THE DECREASING CLOUDS AND WINDS...SHOULD BE A COLD NIGHT OVER
THE INTERIOR LOCATIONS. PWATS AROUND 35 PERCENT OF NORMAL WILL HELP
ENHANCE RADIATIONAL COOLING AND HAVE LOWS IN THE MID SINGLE DIGITS
ABOVE ZERO OVER THE INTERIOR W/CNTRL. WINDS WILL INCREASE SOME OVER
THE FAR W LATE IN THE NIGHT AHEAD OF THE NEXT WAVE...WHICH COULD
LEAD TO A RISE IN TEMPS LATE THERE.
NEXT SHORTWAVE AND ASSOCIATED LOW WILL BE MOVING THROUGH THE NRN
STREAM ON TUES...BUT WITH IT BEING LOCATED MUCH FARTHER N /OVER NRN
ONTARIO AND HUDSON BAY/ EXPECT IT TO HAVE LIMITED AFFECT ON THE
WEATHER OTHER THAN INCREASING THE WSW WINDS. SHOULD BE ANOTHER ABOVE
NORMAL TEMP DAY WITH A MOSTLY SUNNY SKY.
MODELS HAVE CONTINUED THE FASTER TREND WITH MERGING THE SRN STREAM
UPPER LOW CURRENTLY OVER THE SWRN CONUS WITH THE NRN STREAM ON WED
OVER THE LOWER GREAT LKS. WITH THE APPROACHING NRN STREAM WAVE STILL
OVER MANITOBA/SASK...AREA SHOULD BE BETWEEN SYSTEMS AND UNDER WEAK
HIGH PRESSURE TUES NIGHT AND WED MORNING. WILL GO WITH PARTLY CLOUDY
TO MOSTLY CLEAR SKIES FOR NOW...WITH CLOUDS JUST TO THE NW AND SE OF
THE CWA...BUT WILL BE CONTINGENT ON LOW CLOUDS HINTED AT BY THE NAM
NOT STICKING AROUND TOO LONG. THEN WITH SFC TROUGH TO THE
NW...ASSOCIATED WITH LOW OVER HUDSON BAY...NEARING THE CWA IN THE
AFTN AND MOVING THROUGH WED NIGHT...HAVE INCREASED CLOUDS FROM THE
AFTN ON. MOISTURE/FORCING IS WEAK WITH THE PASSAGE OF THE
TROUGH...SO WILL CONTINUE MENTION OF SLIGHTS OVER WRN LK SUPERIOR IN
THE AFTN AND SLIGHTS/LOW CHANCES ALONG THE FRONT WED NIGHT.
UPPER TROUGH THEN SWEEPS ACROSS THE AREA LATE WED NIGHT INTO
FRI...BRINGING A BETTER CHANCE FOR SNOW BEHIND THE FRONT. SOME
DIFFERENCES IN THE H850 TEMPS WITH THE 00Z GFS AND 12Z ECMWF...BUT
OVERALL IDEA IS AROUND -12C...WHICH WOULD CREATE LARGE ENOUGH
DELTA-T VALUES FOR LES. AS IS THE CASE TODAY...H800-650 SUBSIDENCE
AND DRY AIR WILL LIMIT THE INVERSION HEIGHTS TO 4KFT. SHOULD BE
DECENT LLVL MOISTURE TO WORK WITH BELOW THE INVERSION...SO AM
CONFIDENT ENOUGH TO GO WITH CHANCE POPS. WITH THE FORCING BELOW THE
DGZ /CLOUD TOPS ONLY REACH -15C ON THE COLDER GFS/ EXPECT SNOW
RATIOS TO BE IN THE LOW TEENS AND WILL LIKELY ONLY SEE A LIGHT
DUSTING FOR AREAS FAVORED BY A NNW WIND.
UPPER TROUGH STARTS TO SHIFT E ON FRI AS SFC HIGH BEGINS TO PUSH
OVER THE AREA. DRIER AIR ASSOCIATED WITH THE HIGH WILL LEAD TO
DIMINISHING LES POPS THURS NIGHT WEST AND DURING THE DAY FRI
EAST...AS WINDS BECOME ANTICYCLONIC. MAY SEE WEAK UPPER RIDGING ON
SAT...AHEAD OF THE NEXT NRN STREAM TROUGH TO AFFECT THE AREA SAT
NIGHT INTO SUN. ONCE AGAIN...FORCING/MOISTURE LIMITED ALONG THE
FRONT AND THE BEST POTENTIAL FOR PCPN WILL COME ON SUN WITH LES...AS
H850 TEMPS FALL TOWARDS -13C.
&&
.AVIATION /FOR THE 18Z TAF ISSUANCE/...
NW FLOW WILL KEEP MVFR STRATUS DECK OVER UPR MI INTO THIS EVENING.
EXPECT SKIES TO CLEAR THIS EVENING AT KIWD AND KSAW AS SFC HIGH PRES
RIDGE AXIS DROPS SE THRU THE AREA AND WINDS SHIFT WSW. WINDS WILL
CLEAR LATER TONIGHT AT KCMX AS WINDS WILL STAY ONSHORE LONGER THERE.
SW GRADIENT WINDS WILL INCREASE TUESDAY WITH GUSTS APPROACHING 25 KT
AT KIWD AND KSAW BY LATE MORNING/EARLY AFTERNOON.
&&
.MARINE /FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE/...
IN THE WAKE OF A COLD FRONT MOVING SE ACROSS LAKE SUPERIOR...A
PERIOD OF GALE FORCE GUSTS SHOULD OCCUR OVER THE E HALF OF THE LAKE
EARLY THIS MORNING IN ADVANCE OF 5MB/3HR PRES RISES. SINCE CORE OF
PRES RISES WILL SHIFT E OF LAKE SUPERIOR BY MID MORNING...GALE
WARNING WILL MOST LIKELY BE CANCELLED BY NEXT SCHEDULED FCST
ISSUANCE. OTHERWISE...WINDS WILL DIMINISH W TO E TODAY/TONIGHT AS
HIGH PRES QUICKLY APPROACHES AND THEN PASSES ACROSS THE GREAT LAKES.
DEEP LOW PRES MOVING E TO HUDSON BAY EARLY TUE WILL LIKELY BRING
ANOTHER ROUND OF SW GALES TO PORTIONS OF LAKE SUPERIOR...MAINLY THE
W HALF. SW WIND DIRECTION WILL FAVOR THE AREA BTWN THE KEWEENAW AND
ISLE ROYALE FOR STRONGEST WINDS TUE (GUSTS TO AROUND 40KT). GALES
WILL END TUE NIGHT AS PRES GRADIENT WEAKENS. WINDS WILL BE BLO 25KT
WED THRU FRI.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...NONE.
LAKE SUPERIOR...
GALE WARNING UNTIL 1 PM EST THIS AFTERNOON FOR LSZ250-251-266-
267.
GALE WATCH FROM TUESDAY MORNING THROUGH LATE TUESDAY NIGHT FOR
LSZ162-263-264.
GALE WARNING UNTIL 7 AM EST THIS MORNING FOR LSZ264.
LAKE MICHIGAN...NONE.
&&
$$
DISCUSSION...SRF
AVIATION...VOSS
MARINE...ROLFSON
AREA FORECAST DISCUSSION...UPDATED
NWS DULUTH MN
1205 PM CST MON DEC 19 2011
.AVIATION...12/19/18Z ISSUANCE...
MVFR IN LOW CLOUDS ACROSS THE AREA...WITH PATCHY LIGHT SNOW AND
FREEZING DRIZZLE MOSTLY IN AND AROUND THE IRON RANGE INTO EARLY
EVENING. CLOUDS WILL SLOWLY ERODE FROM WEST TO EAST DURING THE
EVENING WITH VFR CLEAR FOLLOWING LATE TONIGHT.
&&
.PREV DISCUSSION... /ISSUED 1143 AM CST MON DEC 19 2011/
UPDATE...LARGE STRATUS CLOUD FIELD WILL REMAIN ANCHORED OVER MOST
OF CWA TODAY WITH SOME BREAKS AROUND SWRN CORNER OF CWA. HAVE
INCREASED SKY COVERAGE IN GRIDS/ZFP. FLURRIES OVER IRON
RANGE....APPEAR TO BE MOVING SE TOWARDS TWIN PORTS. HAVE ADDED
FLURRIES TO MOST OF AREA THROUGH DAY. ALSO...SOME BRIEF ZL REPORTED
NEAR KHIB AND A REPORT FROM PUBLIC NEAR PAYNE AS WELL. WILL NOT
ADD TO GRIDS/ZFP THIS TIME AS IT IS VERY LIGHT AND LIMITED IN AREAL
COVERAGE. WILL MONITOR FOR POTENTIAL UPDATE.
WILL NEED TO REASSESS OVERNIGHT FCST FOR POSSIBLE CHANGES TO
SKY/TEMP GRIDS.
PREV DISCUSSION... /ISSUED 402 AM CST MON DEC 19 2011/
SHORT TERM...TODAY THROUGH TUESDAY...
SURFACE COLD FRONT CONTINUES TO PUSH STEADILY SOUTHWARD THROUGH
WISCONSIN EARLY THIS MORNING IN WAKE OF CLIPPER SYSTEM THAT PASSED
TO OUR NORTH YDAY. THE AIRMASS BEHIND THE COLD FRONT IS NOT
TERRIBLY COLD BY MID DECEMBER STANDARDS FOR THIS PART OF THE WORLD
WITH TEMPS IN THE TEENS TO LOWER 20S..BUT IS ALSO CHARACTERIZED BY
A VERY EXPANSIVE STRATOCUMULUS DECK THAT COVERS ALMOST THE ENTIRE
DULUTH CWA AS OF 330 AM AND EXTENDS SEVERAL HUNDRED MILES TO OUR
NORTH. THE EVOLUTION AND EVENTUAL DISSIPATION OF THIS CLOUD DECK
IS KEY TO THE FORECAST FOR TODAY AND TONIGHT. MOST OF THE SHORT
RANGE MODEL GUIDANCE HAS BEEN INSISTENT FOR MANY MODEL RUNS THAT
THE CLOUDS WILL BREAK UP VERY RAPIDLY THIS MORNING WITH THE HRRR
AND RUC BEING THE OUTLIERS WITH A MUCH MORE SLOW BREAK UP
SOLUTION. GIVEN THE SATELLITE APPEARANCE AND MID DECEMBER
CLIMATOLOGY..WE ARE MUCH LESS OPTIMISTIC THAT CLOUDS WILL BE ABLE
TO BREAK UP AS RAPIDLY AS MUCH OF THE MODEL GUIDANCE SUGGESTS AND
WE HAVE TRENDED TOWARD THE HRRR/RUC SOLUTIONS WHICH CALL FOR
GENERALLY CLOUDY SKIES UNTIL THIS EVENING. NORTHWEST WINDS WILL
CONTINUE TO BE GUSTY THIS MORNING AS 5 MB/3 HR PRESSURE RISE
CENTER CONTINUES TO TRANSLATE ACROSS NRN LAKE SUPERIOR WITH TIGHT
GRADIENT. HOWEVER..WINDS SHUD SLACKEN CONSIDERABLY BY AFTERNOON
WITH LOSS OF ISALLOBARIC COMPONENT AND WEAKENING GRADIENT.
HIGH PRESSURE WILL THEN BUILD INTO THE REGION TONIGHT AND LEAVE
THE AREA LARGELY IN BETWEEN THE BIG SYSTEM COMING OUT ONTO THE
PLAINS TO OUR SOUTH AND THE STRONG WNW FLOW ALOFT ACROSS CANADA.
S/SW FLOW WILL RETURN ON TUESDAY AS RIDGE MOVES TO OUR SOUTH AND
NEXT LOW AMPLITUDE WAVE APPROACHES FROM THE NORTHWEST. THIS
SYSTEM..ON SCHEDULE FOR TUE/TUE NITE..APPEARS TO BE SIMILAR TO
THE ONE THAT JUST PASSED BY WITH A BRIEF SURGE OF WARM AIR
FOLLOWED BY ANOTHER PACIFIC TYPE COLD FRONT TUE NIGHT.
LONG TERM...TUESDAY NIGHT THROUGH SUNDAY...
THE PERIOD SHOULD BEGIN INCREASING CLOUD COVER AS A COLD FRONT IN
MANITOBA AND ONTARIO APPROACHES THE CANADIAN BORDER TUESDAY NIGHT.
THE COLD FRONT WILL LIKELY MOVE THROUGH THE NORTHLAND
WEDNESDAY...RESULTING IN CLOUDY CONDITIONS AND POSSIBLE LIGHT SNOW
ACROSS THE NORTHERN FA. BOTH THE GFS AND ECMWF BRING 850 HPA
TEMPERATURES OF -8 TO -12 CELSIUS OVER WESTERN LAKE SUPERIOR
WEDNESDAY NIGHT AND THURSDAY IN THE WAKE OF THE COLD FRONT.
CONSIDERING THE LAKE SURFACE TEMPERATURE IS AROUND 4 DEGREES
CELSIUS...THAT RESULTS IN SURFACE TO 850 HPA TEMPERATURE DIFFERENCES
AROUND 12 TO 16 DEGREES. THE NORTHERLY WINDS THAT DEVELOP WEDNESDAY
NIGHT AND THURSDAY COULD THEREFORE RESULT IN LAKE EFFECT SNOW ACROSS
THE PARTS OF THE SOUTH SHORE. THE MODELS BRING HIGH PRESSURE INTO
THE UPPER MIDWEST THURSDAY AND FRIDAY...RESULTING IN CLEARING SKIES.
A WARMING TREND LOOKS LIKELY FRIDAY INTO SATURDAY AS SOUTHERLY WINDS
INCREASE AHEAD OF AN APPROACHING COLD FRONT FROM THE WEST. SUNDAY
LOOKS COLDER AND CLOUDY IN THE WAKE OF THE COLD FRONT. THERE MAY BE
SOME LIGHT SNOW.
&&
.POINT TEMPS/POPS...
DLH 27 12 25 16 / 0 0 0 0
INL 23 9 29 18 / 10 0 10 10
BRD 30 11 28 15 / 0 0 0 0
HYR 32 11 26 16 / 10 0 0 0
ASX 32 16 29 20 / 20 0 0 0
&&
.DLH WATCHES/WARNINGS/ADVISORIES...
MN...NONE.
WI...NONE.
LS...SMALL CRAFT ADVISORY UNTIL 4 PM CST THIS AFTERNOON FOR LSZ146-
147.
&&
$$
SHORT TERM...CANNON
LONG TERM....EOM
AVIATION...EOM
AREA FORECAST DISCUSSION...UPDATED
NWS DULUTH MN
1143 AM CST MON DEC 19 2011
.UPDATE...LARGE STRATUS CLOUD FIELD WILL REMAIN ANCHORED OVER MOST
OF CWA TODAY WITH SOME BREAKS AROUND SWRN CORNER OF CWA. HAVE
INCREASED SKY COVERAGE IN GRIDS/ZFP. FLURRIES OVER IRON
RANGE....APPEAR TO BE MOVING SE TOWARDS TWIN PORTS. HAVE ADDED
FLURRIES TO MOST OF AREA THROUGH DAY. ALSO...SOME BRIEF ZL REPORTED
NEAR KHIB AND A REPORT FROM PUBLIC NEAR PAYNE AS WELL. WILL NOT
ADD TO GRIDS/ZFP THIS TIME AS IT IS VERY LIGHT AND LIMITED IN AREAL
COVERAGE. WILL MONITOR FOR POTENTIAL UPDATE.
WILL NEED TO REASSESS OVERNIGHT FCST FOR POSSIBLE CHANGES TO
SKY/TEMP GRIDS.
&&
.PREV DISCUSSION... /ISSUED 542 AM CST MON DEC 19 2011/
AVIATION...12Z TAF ISSUANCE
A LARGE MVFR STRATUS DECK COVERS MANITOBA/ONTARIO/NORTHERN
MN/NORTHWESTERN WI THIS MORNING. MANY MODELS INDICATE THIS LAYER
WILL QUICKLY DISSIPATE THIS MORNING...BUT AM BETTING AGAINST THE
MODELS AND THINK IT WILL BE DIFFICULT FOR THIS STRATUS DECK TO
DISSIPATE. THEREFORE...FORECASTING MVFR CIGS AT ALL TAF SITES
THROUGH AT LEAST THE EARLY AFTERNOON WITH CLEARING BY THIS EVENING.
EXPECT NORTHWEST WINDS AROUND 10 TO 15 KNOTS WHICH WILL RELAX LATE
THIS AFTERNOON AND BECOME VERY LIGHT OVERNIGHT. WIND GUSTS OF 15 TO
25 KNOTS ARE POSSIBLE AT KDLH/KHIB/KINL/KBRD THROUGH MID
MORNING...AND THEN WINDS WILL BECOME LESS GUSTY BY AFTERNOON. LIGHT
SOUTHWEST WINDS WILL BEGIN TO DEVELOP LATE TONIGHT. WIND SHEAR MAY
BE AN ISSUE AT KINL LATE TONIGHT.
PREV DISCUSSION... /ISSUED 402 AM CST MON DEC 19 2011/
SHORT TERM...TODAY THROUGH TUESDAY...
SURFACE COLD FRONT CONTINUES TO PUSH STEADILY SOUTHWARD THROUGH
WISCONSIN EARLY THIS MORNING IN WAKE OF CLIPPER SYSTEM THAT PASSED
TO OUR NORTH YDAY. THE AIRMASS BEHIND THE COLD FRONT IS NOT
TERRIBLY COLD BY MID DECEMBER STANDARDS FOR THIS PART OF THE WORLD
WITH TEMPS IN THE TEENS TO LOWER 20S..BUT IS ALSO CHARACTERIZED BY
A VERY EXPANSIVE STRATOCUMULUS DECK THAT COVERS ALMOST THE ENTIRE
DULUTH CWA AS OF 330 AM AND EXTENDS SEVERAL HUNDRED MILES TO OUR
NORTH. THE EVOLUTION AND EVENTUAL DISSIPATION OF THIS CLOUD DECK
IS KEY TO THE FORECAST FOR TODAY AND TONIGHT. MOST OF THE SHORT
RANGE MODEL GUIDANCE HAS BEEN INSISTENT FOR MANY MODEL RUNS THAT
THE CLOUDS WILL BREAK UP VERY RAPIDLY THIS MORNING WITH THE HRRR
AND RUC BEING THE OUTLIERS WITH A MUCH MORE SLOW BREAK UP
SOLUTION. GIVEN THE SATELLITE APPEARANCE AND MID DECEMBER
CLIMATOLOGY..WE ARE MUCH LESS OPTIMISTIC THAT CLOUDS WILL BE ABLE
TO BREAK UP AS RAPIDLY AS MUCH OF THE MODEL GUIDANCE SUGGESTS AND
WE HAVE TRENDED TOWARD THE HRRR/RUC SOLUTIONS WHICH CALL FOR
GENERALLY CLOUDY SKIES UNTIL THIS EVENING. NORTHWEST WINDS WILL
CONTINUE TO BE GUSTY THIS MORNING AS 5 MB/3 HR PRESSURE RISE
CENTER CONTINUES TO TRANSLATE ACROSS NRN LAKE SUPERIOR WITH TIGHT
GRADIENT. HOWEVER..WINDS SHUD SLACKEN CONSIDERABLY BY AFTERNOON
WITH LOSS OF ISALLOBARIC COMPONENT AND WEAKENING GRADIENT.
HIGH PRESSURE WILL THEN BUILD INTO THE REGION TONIGHT AND LEAVE
THE AREA LARGELY IN BETWEEN THE BIG SYSTEM COMING OUT ONTO THE
PLAINS TO OUR SOUTH AND THE STRONG WNW FLOW ALOFT ACROSS CANADA.
S/SW FLOW WILL RETURN ON TUESDAY AS RIDGE MOVES TO OUR SOUTH AND
NEXT LOW AMPLITUDE WAVE APPROACHES FROM THE NORTHWEST. THIS
SYSTEM..ON SCHEDULE FOR TUE/TUE NITE..APPEARS TO BE SIMILAR TO
THE ONE THAT JUST PASSED BY WITH A BRIEF SURGE OF WARM AIR
FOLLOWED BY ANOTHER PACIFIC TYPE COLD FRONT TUE NIGHT.
LONG TERM...TUESDAY NIGHT THROUGH SUNDAY...
THE PERIOD SHOULD BEGIN INCREASING CLOUD COVER AS A COLD FRONT IN
MANITOBA AND ONTARIO APPROACHES THE CANADIAN BORDER TUESDAY NIGHT.
THE COLD FRONT WILL LIKELY MOVE THROUGH THE NORTHLAND
WEDNESDAY...RESULTING IN CLOUDY CONDITIONS AND POSSIBLE LIGHT SNOW
ACROSS THE NORTHERN FA. BOTH THE GFS AND ECMWF BRING 850 HPA
TEMPERATURES OF -8 TO -12 CELSIUS OVER WESTERN LAKE SUPERIOR
WEDNESDAY NIGHT AND THURSDAY IN THE WAKE OF THE COLD FRONT.
CONSIDERING THE LAKE SURFACE TEMPERATURE IS AROUND 4 DEGREES
CELSIUS...THAT RESULTS IN SURFACE TO 850 HPA TEMPERATURE DIFFERENCES
AROUND 12 TO 16 DEGREES. THE NORTHERLY WINDS THAT DEVELOP WEDNESDAY
NIGHT AND THURSDAY COULD THEREFORE RESULT IN LAKE EFFECT SNOW ACROSS
THE PARTS OF THE SOUTH SHORE. THE MODELS BRING HIGH PRESSURE INTO
THE UPPER MIDWEST THURSDAY AND FRIDAY...RESULTING IN CLEARING SKIES.
A WARMING TREND LOOKS LIKELY FRIDAY INTO SATURDAY AS SOUTHERLY WINDS
INCREASE AHEAD OF AN APPROACHING COLD FRONT FROM THE WEST. SUNDAY
LOOKS COLDER AND CLOUDY IN THE WAKE OF THE COLD FRONT. THERE MAY BE
SOME LIGHT SNOW.
&&
.POINT TEMPS/POPS...
DLH 27 12 25 16 / 0 0 0 10
INL 23 9 29 18 / 10 0 10 10
BRD 30 11 28 15 / 0 0 0 10
HYR 32 11 26 16 / 10 0 0 0
ASX 32 16 29 20 / 20 0 0 0
&&
.DLH WATCHES/WARNINGS/ADVISORIES...
MN...NONE.
WI...NONE.
LS...SMALL CRAFT ADVISORY UNTIL 4 PM CST THIS AFTERNOON FOR LSZ146-
147.
&&
$$
SHORT TERM...CANNON
AREA FORECAST DISCUSSION
NWS HASTINGS NE
349 PM CST MON DEC 19 2011
.SHORT TERM...MORNING UPPER AIR ANALYSIS AND WATER VAPOR IMAGERY
INDICATE A MID AND UPPER LEVEL LOW OVER WEST TEXAS...MOVING NORTHEAST
INTO THE CENTRAL CONUS. WATER VAPOR IMAGERY ALSO INDICATES A MID
LEVEL DRY INTRUSION MOVING NORTHEASTWARD INTO NORTHERN TEXAS AND
PORTIONS OF OKLAHOMA. AT THE SURFACE AN AREA OF LOW PRESSURE EXISTS OVER
THE PANHANDLE OF TEXAS AND A SURFACE FRONT EXTENDS NORTHEAST FROM
THE SURFACE LOW INTO WESTERN AND NORTHERN OKLAHOMA...AS WELL AS
EASTERN KANSAS. KUEX INDICATES INCOMING PRECIPITATION OVER NORTH
CENTRAL KANSAS IN A ZONE OF LOW LEVEL THERMAL ADVECTION AND
RESULTANT ISENTROPIC UPGLIDE AND SATURATION. ADDITIONAL FORCING
THROUGH A ZONE OF MID LEVEL DIFFLUENCE IS ALSO HELPING PROMOTE
PRECIPITATION OVER AREAS NORTHEAST OF THE MID LEVEL LOW. SNOW IS
ALREADY IN PROGRESS AT NATOMA AS A RESULT.
THE LOW LEVEL BAROCLINIC ZONE CLEARED OUR CWA EARLIER TODAY AND
THE LOW LEVEL WIND FIELD ACROSS OUR CWA REMAINS FROM THE
NORTH/NORTHEAST AS A RESULT. SURFACE TEMPERATURES HAVE BEEN AT A
NEAR STANDSTILL IF NOT FALLING SOMEWHAT TODAY...WITH TEMPERATURES
AS OF MID AFTERNOON GENERALLY IN THE LOWER 30S. SHORT TERM GUIDANCE
CONTINUES TO SUGGEST THE MID LEVEL LOW WILL MOVE NORTHEAST ACROSS
THE SOUTHERN AND CENTRAL PLAINS TONIGHT AND TUESDAY. LOW LEVEL
THERMAL ADVECTION...WORKING IN CONCERT WITH MID LEVEL DIFFLUENCE AND
DEFORMATION TO THE NORTH AND NORTHEAST OF THE MID LEVEL LOW...WILL CONTINUE
PROMOTING PRECIPITATION PRODUCTION OVER THE AREA TONIGHT.
PRECIPITATION IS ALSO EXPECTED DURING THE DAY TUESDAY AS MID LEVEL
DEFORMATION TO THE NORTH AND NORTHWEST OF THE MID LEVEL LOW CLEARS
THE AREA.
MOISTURE THROUGH THE LOWER HALF OF THE TROPOSPHERIC COLUMN IS
EXPECTED TO REMAIN QUITE HIGH THROUGH THE NEXT 24 HOURS WITH 500MB
DEW POINTS IN EXCESS OF -25 DEGREES C AND 700MB DEW POINTS IN
EXCESS OF -10 DEGREES C ACROSS OUR SOUTH/SOUTHEAST. THESE MOISTURE
LEVELS...WORKING IN CONCERT WITH THE AFOREMENTIONED KINEMATIC
FORCING...SHOULD BE MORE THAN SUFFICIENT FOR SIGNIFICANT
PRECIPITATION PRODUCTION ACROSS OUR SOUTH AND SOUTHEAST TONIGHT AND
TOMORROW. QPF FIELDS FROM THE NAM...OPERATIONAL GFS...EC AND SREF-
MEAN ALL SUGGEST STORM TOTAL LIQUID PRECIPITATION AMOUNTS IN
EXCESS OF 0.80" ACROSS OUR SOUTH AND SOUTHEAST. SURFACE
TEMPERATURES WILL LIKELY FALL INTO THE UPPER AND MID 20S THROUGH
THE REMAINDER OF THE EVENT AND AS A RESULT WILL GO AHEAD AND
ASSUME A 10:1 SNOW-WATER RATIO TO START THE EVENT...WITH RATIOS
CLIMBING TO NEAR 13:1 BY TONIGHT AND TOMORROW. THIS YIELDS STORM
TOTAL SNOWFALL ACCUMULATIONS ON THE ORDER OF 5-12 INCHES ACROSS
OUR EXTREME SOUTH...AND STORM TOTAL SNOWFALL ACCUMULATIONS IN THE
1-5 INCH RANGE FARTHER NORTH.
LOW LEVEL PRESSURE RISES POST-FROPA HAVE PROMOTED AN INCREASED LOW
LEVEL PRESSURE GRADIENT TODAY...WITH SUSTAINED WINDS NEAR 20KTS
ACROSS MUCH OF THE CWA AS OF MID AFTERNOON. THESE CONDITIONS ARE EXPECTED
TO CONTINUE THROUGH THIS EVENING...WITH DIMINISHING WINDS EXPECTED
BY MIDNIGHT AS THE LOW LEVEL PRESSURE GRADIENT RELAXES. AS A
RESULT...THESE WINDS SHOULD REMAIN WELL BELOW BLIZZARD CRITERIA.
ALL THAT BEING SAID...THE INHERITED WINTER STORM WARNING FOR
ROOKS...OSBORNE AND MITCHELL COUNTIES...ALONG WITH THE WINTER
WEATHER ADVISORY FOR PHILLIPS...SMITH AND JEWELL COUNTIES...APPEAR
TO BE RIGHT ON...BUT DID GO AHEAD AND START THE WINTER STORM
WARNING NOW GIVEN SNOWFALL IS ALREADY OCCURRING AT NATOMA.
JUST A FEW THINGS TO CONSIDER AS WE HEAD INTO THIS STORM. THE
CONTRAST BETWEEN MOIST AIR AND DRY AIR...AS WELL AS BETWEEN STRONG
KINEMATIC FORCING AND NEXT TO NO FORCING...IS EXPECTED TO BE RATHER
SHARP THUS RESULTING IN A VERY TIGHT GRADIENT OF STORM TOTAL
SNOWFALL ACCUMULATIONS. ALTHOUGH CONFIDENCE REMAINS HIGH REGARDING
ACTUAL STORM TOTAL SNOWFALL ACCUMULATIONS...THE AXIS OF HEAVIEST
SNOW COULD SHIFT DRAMATICALLY IN RESPONSE TO VERY SMALL DEVIATIONS
IN STORM PATH. THANKFULLY...GUIDANCE HAS REMAINED FAIRLY
CONSISTENT WITH RESPECT TO STORM PATH...A TREND WHICH WE HOPE WILL
CONTINUE. FINALLY...GUIDANCE DOES SUGGEST THE MID LEVEL DRY
INTRUSION WILL INFILTRATE MUCH OF KANSAS BY TUESDAY MORNING...THUS
DRYING OUT THE DENDRITIC LAYER AND LIKELY LEADING TO A PERIOD OF
FREEZING DRIZZLE. AT THIS TIME IT APPEARS THIS MID LEVEL DRY
INTRUSION SHOULD REMAIN SOUTH AND SOUTHEAST OF OUR AREA AND AS A
RESULT...LEFT ANY MENTION OF FREEZING DRIZZLE OUT OF THE FORECAST.
.LONG TERM...TUESDAY NIGHT THROUGH MONDAY. THE UPPER LOW WILL
CONTINUE TO MOVE NORTHEAST AND AWAY FROM THE AREA TUESDAY NIGHT.
THE MAJORITY OF MODEL SOLUTIONS SUGGESTS THE SNOW SHOULD BE DONE BY
TUESDAY NIGHT...AND WILL CONTINUE TO CARRY A DRY FORECAST.
A BRIEF H5 RIDGE BUILDS IN TUESDAY NIGHT INTO WEDNESDAY...WHICH
SHOULD KEEP IT DRY THROUGH WEDNESDAY...HOWEVER ANOTHER UPPER
TROUGH/LOW BEGINS TO APPROACH THE REGION WEDNESDAY NIGHT. THE
NAM/GFS/ECMWF ALL AGREE THAT MOST OF WEDNESDAY EVENING SHOULD REMAIN
DRY...HOWEVER LIGHT SNOW COULD BEGIN TO APPROACH FAR NORTH AND WEST
PORTIONS OF THE FORECAST AREA BY LATE EVENING. THE SNOW CHANCES
WILL THEN SPREAD ACROSS THE FORECAST AREA OVERNIGHT WEDNESDAY INTO
THURSDAY. THE NAM/GFS DEPICT THE STRONGEST LIFT/FORCING ACROSS
ROUGHLY THE SOUTHERN HALF OF THE CWA LATE WEDNESDAY NIGHT INTO
THURSDAY...AND HAVE INCREASED POPS FOR THAT AREA...ESPECIALLY FOR
THURSDAY. SNOW AMOUNTS ARE STILL UNCERTAIN...AND SREF 12 HOUR SNOW
PROBABILITIES FOR AN INCH OR MORE OF SNOW ARE NOT VERY HIGH...THOUGH
THE HIGHER PROBABILITIES ARE SHOWN IN THE SOUTH AND WEST.
ONE CONCERN IS THE POTENTIAL FOR HIGHER SNOW RATIOS WITH THE CARIBOU
SNOW TECHNIQUE SUGGESTING RATIOS CLIMBING TO NEAR 18 TO 1 FOR
THURSDAY AFTERNOON. FOR NOW...WILL GO WITH A GENERAL HALF INCH TO
INCH AND A HALF...WITH THE HIGHER AMOUNTS IN THE SOUTH AND WEST.
THERE IS STILL PLENTY OF TIME TO REFINE AMOUNTS AS THIS NEXT SYSTEM
GETS CLOSER.
OVERALL...THE CHRISTMAS HOLIDAY WEEKEND LOOKS TO BE FAIRLY QUIET.
ANOTHER WAVE COULD MOVE ACROSS THE REGION SATURDAY NIGHT INTO
CHRISTMAS DAY...BUT MOISTURE IS LACKING SO IT SHOULD PASS THROUGH
DRY. TEMPERATURES ARE EXPECTED TO BE FAIRLY SEASONABLE WITH HIGHS
PRIMARILY IN THE 30S.
&&
PREV DISCUSSION... /ISSUED 1120 AM CST MON DEC 19 2011/
AVIATION...18Z TAF. IFR CEILINGS HAVE MOVED INTO PARTS OF SOUTH
CENTRAL NEBRASKA BEHIND A COLD FRONT THAT TRAVELED ACROSS THE
AREA EARLIER TODAY. THE GENERAL TREND HAS BEEN FOR THE IFR
CEILINGS TO LIFT TO MVFR...AND THIS IS ALSO SHOWN BY THE LATEST
NAM PROXIMITY SOUNDINGS..SO WILL ONLY CARRY THE LOWER CEILINGS IN
A BRIEF TEMPO GROUP. PROXIMITY SOUNDINGS ALSO SHOW THE MVFR
CEILINGS IMPROVING THIS AFTERNOON...THOUGH THE RUC IS FASTER IN
LIFTING THE CEILINGS THAN THE NAM. WILL AIM FOR MORE OF A
COMPROMISE SOLUTION AND GO WITH 21Z AS A START. WINDS WILL REMAIN
GUSTY AND FROM THE NORTH MOST OF THE AFTERNOON...BUT THEY SHOULD
DIMINISH THIS EVENING. THERE WILL BE CHANCES OF SNOW SOUTH OF
KGRI AS A STORM SYSTEM MOVES ACROSS THE CENTRAL AND SOUTHERN
PLAINS...BUT THINK THAT THE CHANCES WILL STAY FAR ENOUGH SOUTH TO
KEEP THE MENTION OUT OF THE FORECAST AT KGRI.
&&
.GID WATCHES/WARNINGS/ADVISORIES...
NE...NONE.
KS...WINTER WEATHER ADVISORY UNTIL 6 PM CST TUESDAY FOR KSZ005>007.
WINTER STORM WARNING UNTIL 6 PM CST TUESDAY FOR KSZ017>019.
&&
$$
SHORT TERM...BRYANT
AREA FORECAST DISCUSSION
NWS HASTINGS NE
1237 PM CST MON DEC 19 2011
.UPDATE...MORNING UPPER AIR ANALYSIS AND WATER VAPOR IMAGERY
INDICATE A MID AND UPPER LEVEL LOW OVER NEW MEXICO BEGINNING TO
MOVE NORTHEAST INTO THE CENTRAL CONUS. WATER VAPOR IMAGERY ALSO
INDICATES A MID LEVEL DRY INTRUSION MOVING NORTHEASTWARD ACROSS
WEST TEXAS. AT THE SURFACE AN AREA OF LOW PRESSURE EXISTS OVER THE
PANHANDLE OF TEXAS AND A SURFACE FRONT EXTENDS NORTHEAST FROM THE
SURFACE LOW INTO WESTERN AND NORTHERN OKLAHOMA AS WELL AS EASTERN
KANSAS. RADAR DATA FROM SITES ACROSS KANSAS...AS WELL AS
KUEX...INDICATE INCOMING PRECIPITATION ACROSS THE SOUTHERN TWO-
THIRDS OF KANSAS IN A ZONE OF LOW LEVEL THERMAL ADVECTION AND
RESULTANT ISENTROPIC UPGLIDE AND SATURATION. ADDITIONAL FORCING
THROUGH A ZONE OF DIFFLUENCE IS ALSO HELPING PROMOTE PRECIPITATION
OVER AREAS NORTHEAST OF THE MID LEVEL LOW.
THE LOW LEVEL BAROCLINIC ZONE CLEARED OUR CWA EARLIER TODAY AND THE LOW
LEVEL WIND FIELD ACROSS OUR CWA REMAINS FROM THE NORTH/NORTHEAST
AS A RESULT. SURFACE TEMPERATURES HAVE BEEN AT A NEAR STANDSTILL
IF NOT FALLING SOMEWHAT THROUGH THE MORNING HOURS...WITH
TEMPERATURES AT MIDDAY GENERALLY IN THE LOWER 30S. SHORT TERM
GUIDANCE CONTINUES TO SUGGEST THE MID LEVEL LOW WILL MOVE
NORTHEAST ACROSS THE SOUTHERN AND CENTRAL PLAINS TONIGHT AND
TUESDAY. LOW LEVEL THERMAL ADVECTION WORKING IN CONCERT WITH MID
LEVEL DIFFLUENCE AND DEFORMATION TO THE NORTH AND NORTHEAST OF THE
MID LEVEL LOW WILL ALSO CONTINUE PROMOTING PRECIPITATION
PRODUCTION ACROSS THE REGION...WITH PRECIPITATION EXPECTED OVER
SOUTH AND SOUTHEASTERN PORTIONS OF OUR CWA STARTING LATE THIS
AFTERNOON. PRECIPITATION SHOULD THEN CONTINUE OVER THE AREA
TONIGHT AS LOW LEVEL THERMAL ADVECTION AND MID LEVEL DIFFLUENCE
AND DEFORMATION ALSO CONTINUE OVER THE AREA...WITH PRECIPITATION
ALSO EXPECTED DURING THE DAY TUESDAY AS MID LEVEL DEFORMATION TO
THE NORTH AND NORTHWEST OF THE MID LEVEL LOW CLEARS THE AREA.
MOISTURE THROUGH THE LOWER HALF OF THE TROPOSPHERIC COLUMN IS
EXPECTED TO REMAIN QUITE HIGH THROUGH THE NEXT 24 HOURS WITH 500MB
DEW POINTS IN EXCESS OF -25 DEGREES C AND 700MB DEW POINTS IN
EXCESS OF -10 DEGREES C ACROSS OUR SOUTH/SOUTHEAST. THESE MOISTURE
LEVELS...WORKING IN CONCERT WITH THE AFOREMENTIONED KINEMATIC
FORCING...SHOULD BE MORE THAN SUFFICIENT FOR SIGNIFICANT
PRECIPITATION PRODUCTION ACROSS OUR SOUTH AND SOUTHEAST TONIGHT AND
TOMORROW. QPF FIELDS FROM THE NAM...OPERATIONAL GFS...EC AND SREF-
MEAN ALL SUGGEST STORM TOTAL LIQUID PRECIPITATION AMOUNTS IN
EXCESS OF 0.80" ACROSS OUR SOUTH/SOUTHEAST. SURFACE TEMPERATURES
SHOULD START THE EVENT NEAR 30...BUT WILL LIKELY FALL INTO THE
UPPER 20S AND MID 20S THROUGH THE REMAINDER OF THE EVENT. GIVEN
THIS...WILL GO AHEAD AND ASSUME A 10:1 SNOW-WATER RATIO TO START
THE EVENT...WITH RATIOS CLIMBING TO NEAR 13:1 BY TONIGHT AND
TOMORROW. THIS YIELDS STORM TOTAL SNOWFALL ACCUMULATIONS ON THE
ORDER OF 5-12 INCHES ACROSS OUR EXTREME SOUTH...WITH STORM TOTAL
SNOWFALL ACCUMULATIONS IN THE 1-5 INCH RANGE FARTHER NORTH.
LOW LEVEL PRESSURE RISES POST-FROPA HAVE PROMOTED AN INCREASED LOW
LEVEL PRESSURE GRADIENT THIS MORNING...WITH SUSTAINED WINDS
ALREADY IN EXCESS OF 20KTS ACROSS MUCH OF THE CWA. THESE
CONDITIONS ARE EXPECTED TO CONTINUE THROUGH THIS AFTERNOON AND
INTO THIS EVENING...WITH DIMINISHING WINDS EXPECTED BY MIDNIGHT AS
THE LOW LEVEL PRESSURE GRADIENT RELAXES. THE STRONGEST LOW LEVEL
PRESSURE RISES ARE SUPPOSE TO BE OCCURRING NOW BASED ON SHORT TERM
GUIDANCE...THUS DO NOT ANTICIPATE THE NEED FOR A WIND ADVISORY FOR
THIS AFTERNOON. ADDITIONALLY...THESE WINDS SHOULD REMAIN WELL
BELOW BLIZZARD CRITERIA THUS DO NOT ANTICIPATE A BLIZZARD WARNING
WILL BE NEEDED FOR TONIGHT OR TOMORROW.
ALL THAT BEING SAID...THE INHERITED WINTER STORM WARNING FOR
ROOKS...OSBORNE AND MITCHELL COUNTIES...ALONG WITH THE WINTER
WEATHER ADVISORY FOR PHILLIPS...SMITH AND JEWELL COUNTIES...APPEAR
TO BE RIGHT ON AND NO CHANGES TO THE HEADLINES ARE CURRENTLY ANTICIPATED.
JUST A FEW THINGS TO CONSIDER AS WE HEAD INTO THIS STORM. THE
CONTRAST BETWEEN MOIST AIR AND DRY AIR...AS WELL AS BETWEEN STRONG
KINEMATIC FORCING AND NEXT TO NO FORCING...IS EXPECTED TO BE RATHER
SHARP THUS RESULTING IN A VERY TIGHT GRADIENT OF STORM TOTAL
SNOWFALL ACCUMULATIONS. ALTHOUGH CONFIDENCE REMAINS HIGH REGARDING
ACTUAL STORM TOTAL SNOWFALL ACCUMULATIONS...THE AXIS OF HEAVIEST
SNOW COULD SHIFT DRAMATICALLY IN RESPONSE TO VERY SMALL DEVIATIONS
IN STORM PATH. THANKFULLY...GUIDANCE HAS REMAINED FAIRLY
CONSISTENT WITH RESPECT TO STORM PATH...A TREND WHICH WE HOPE WILL
CONTINUE. FINALLY...GUIDANCE DOES SUGGEST THE MID LEVEL DRY
INTRUSION WILL INFILTRATE MUCH OF KANSAS LATER THIS EVENING...THUS
DRYING OUT THE DENDRITIC LAYER AND LIKELY LEADING TO A PERIOD OF
FREEZING DRIZZLE. AT THIS TIME IT APPEARS THIS MID LEVEL DRY
INTRUSION SHOULD REMAIN SOUTH/SOUTHEAST OF OUR AREA AND AS A
RESULT...LEFT ANY MENTION OF FREEZING DRIZZLE OUT OF THE FORECAST.
&&
.PREV DISCUSSION... /ISSUED 1120 AM CST MON DEC 19 2011/
AVIATION...18Z TAF. IFR CEILINGS HAVE MOVED INTO PARTS OF SOUTH
CENTRAL NEBRASKA BEHIND A COLD FRONT THAT TRAVELED ACROSS THE
AREA EARLIER TODAY. THE GENERAL TREND HAS BEEN FOR THE IFR
CEILINGS TO LIFT TO MVFR...AND THIS IS ALSO SHOWN BY THE LATEST
NAM PROXIMITY SOUNDINGS..SO WILL ONLY CARRY THE LOWER CEILINGS IN
A BRIEF TEMPO GROUP. PROXIMITY SOUNDINGS ALSO SHOW THE MVFR
CEILINGS IMPROVING THIS AFTERNOON...THOUGH THE RUC IS FASTER IN
LIFTING THE CEILINGS THAN THE NAM. WILL AIM FOR MORE OF A
COMPROMISE SOLUTION AND GO WITH 21Z AS A START. WINDS WILL REMAIN
GUSTY AND FROM THE NORTH MOST OF THE AFTERNOON...BUT THEY SHOULD
DIMINISH THIS EVENING. THERE WILL BE CHANCES OF SNOW SOUTH OF
KGRI AS A STORM SYSTEM MOVES ACROSS THE CENTRAL AND SOUTHERN
PLAINS...BUT THINK THAT THE CHANCES WILL STAY FAR ENOUGH SOUTH TO
KEEP THE MENTION OUT OF THE FORECAST AT KGRI.
PREV DISCUSSION... /ISSUED 511 AM CST MON DEC 19 2011/
SHORT TERM...TODAY THROUGH WEDNESDAY NIGHT. PRIMARY FORECAST
CONCERN LIES WITH PRECIPITATION CHANCES TODAY THROUGH TUESDAY.
SEEING THE RELATIVE QUIET BEFORE THE STORM EARLY THIS
MORNING...BUT THE NEXT SYSTEM OF INTEREST IS QUITE EVIDENT ON
SATELLITE IMAGERY. THE MAIN UPPER LEVEL LOW PRESSURE SYSTEM TAKING
AIM ON THE PLAINS IS CURRENTLY SPINNING OVER SRN NEW
MEXICO...WHILE THE NORTHERN STREAM SHORTWAVE TROUGH ALSO AFFECTING
THE REGION CONTINUES TO SHIFT SOUTHEAST OUT OF CENTRAL CANADA AND
INTO THE DAKOTAS. AT THE SURFACE...THE COLD FRONT HAS BEEN MAKING
ITS WAY SOUTH OVERNIGHT...AND CURRENTLY IS DRAPED THROUGH THE
CENTRAL PORTIONS OF THE CWA...BRINGING NORTHWESTERLY WINDS BEHIND
IT...BUT THE MORE GUSTY WINDS ARE FOR THE TIME BEING LAGGING JUST
A BIT FURTHER NORTH. THE CWA IS ALSO SEEING INCREASED LOW TO MID
LEVEL MOISTURE AND CLOUD COVER STREAM NORTH FROM THE MAIN STORM
SYSTEM...WHILE LOW LEVEL STRATUS ACCOMPANYING THE SURFACE COLD
FRONT CONTINUES TO PUSH SOUTH AND WILL BE POKING INTO THE NORTHERN
CWA WITHIN THE NEXT HOUR.
THE MOST ACTIVE PERIOD IN THE SHORT TERM CONTINUES TO LIE ROUGHLY
BETWEEN MIDDAY TODAY THROUGH MIDDAY TUESDAY. THE NORTHERN STREAM
SHORTWAVE TROUGH MOVING THROUGH THE DAKOTAS WILL CONTINUE TO PUSH
THE SURFACE COLD FRONT FURTHER SOUTH INTO CENTRAL PORTIONS OF
KANSAS BY MIDDAY. THE UPPER LEVEL LOW PRESSURE SYSTEM WILL
CONTINUE TO PUSH EAST THROUGH NEW MEXICO THROUGH THE DAY...AND BY
LATE THIS EVENING IS EXPECTED TO BE CENTERED OVER THE PANHANDLE OF
TEXAS. THROUGH THE REMAINDER OF THE OVERNIGHT HOURS AND THROUGH
TUESDAY...THE SYSTEM WILL CONTINUE ITS NORTHEASTWARD
TREK...CROSSING THROUGH SOUTH CENTRAL AND EASTERN KANSAS...AND
LOOKS TO END UP NEAR THE KANSAS CITY AREA BY TUESDAY EVENING.
ISENTROPIC LIFT RAMPING UP OUT AHEAD OF THE SYSTEM WILL BRING
INCREASING PRECIPITATION CHANCES...ESPECIALLY STARTING THIS
AFTERNOON...WITH CHANCES CONTINUING OVERNIGHT AND INTO TUESDAY
WITH BETTER FRONTOGENETICAL FORCING AND WITH THE SYSTEM ITSELF
PASSES THROUGH THE REGION. MAIN CHANGES MADE TO THE FORECAST WERE
TO INCREASE POPS...MAINLY ACROSS NC KS. HOWEVER...EVEN THIS CLOSE
TO THE EVENT...SOME UNCERTAINTY EXISTS BECAUSE OF INCONSISTENCIES
BETWEEN MODELS. THE 00Z RUNS OF MANY MODELS DEPICTED A SLIGHT
NORTHWARD TREND TO THINGS...WHICH WAS CONCERNING FOR MORE OF THE
CWA...ONLY TO SEE THE 06Z RUNS STARTING TO PUSH THINGS BACK CLOSER
TO WHERE THEY WERE LAST NIGHT. BECAUSE OF THIS...DIDNT MAKE
SIGNIFICANT CHANGES TO POPS IN SC NEB...THOUGH CONFIDENCE IS NOT
HIGH IN JUST HOW FAR NORTH SNOW WILL ACTUALLY FALL. IF TRENDS FROM
CURRENT MODEL RUNS HOLD...FORECAST POPS ARE TOO FAR NORTH...BUT AT
THIS POINT DO HAVE LIGHT ACCUMULATIONS ALONG AND JUST NORTH OF
HIGHWAY 6.
DECIDED TO UPGRADE THE WATCH ACROSS THE SRN 3 COUNTIES TO A WINTER
STORM WARNING...THERE HAS BEEN MORE CONSISTENCY WITH MODELS
SHOWING THE GREATER QPF IN THOSE AREAS AND TO THE SOUTH...AND
FEEL THAT SOUTHERN PORTIONS OF THOSE COUNTIES COULD END UP SEEING
ARND 8 INCHES OF SNOW. STILL EXPECTING A SHARP GRADIENT WITH
PRECIPITATION AMOUNTS AS ONE GOES FURTHER NORTH...BUT THERE IS
STILL THE POTENTIAL FOR PHILLIPS/SMITH/JEWELL COUNTIES TO SEE 2 TO
6 INCHES OF SNOW /THE HIGHER AMOUNTS ARE EXPECTED TO BE IN JEWELL
COUNTY/...SO A WINTER WX ADV WAS ISSUED FOR THOSE COUNTIES.
CONSIDERED THROWING NUCKOLLS/THAYER IN AS WELL...BUT CURRENT
FORECAST TOTALS WERE ONLY IN THE 1 TO 3 RANGE. DAY SHIFT WILL HAVE
TO ASSESS 12Z RUNS TO SEE IF THEY DO NEED TO BE ADDED.
SOMETHING ELSE TO ADD TO THE SNOW CONCERN IS THE EXPECTED INCREASE
IN WINDS. WHILE THE MAIN FRONT WILL SHIFT SOUTH OF THE CWA...THE
APPROACHING STORM FROM THE SW WILL PREVENT IT FROM COMPLETELY
CLEARING THE AREA...AND WITH HIGH PRESSURE BUILDING IN FROM THE
NORTHWEST...IT WILL LEAD TO A TIGHTENING PRESSURE GRADIENT. THERE
IS EXPECTED TO BE AN INCREASE IN WINDS ACROSS THE CWA WITH THE
INITIAL FRONTAL PASSAGE...WITH THAT TIGHTER GRADIENT SETTING UP
THIS AFTERNOON AND EVENING. SPEEDS INCREASING TO 20 TO 30 MPH WITH
HIGHER GUSTS WILL BE COMMON ACROSS THE CWA...BUT NORTHERN AREAS
WILL START TO SEE SPEEDS TAPER OFF SOONER THAN SOUTHERN AREAS.
THESE SPEEDS STICKING AROUND LONGER IN THE SOUTH CORRESPONDS WITH
THE ONSET OF THE PRECIPITATION LATER TODAY/TONIGHT...WHICH WILL
RESULT IN SOME TRAVEL DIFFICULTIES DUE TO VISIBILITY RESTRICTIONS.
AS WE GET INTO TOMORROW...WILL START TO SEE PRECIPITATION
BEGINNING TO WIND DOWN...ESPECIALLY TOWARD MIDDAY AND INTO THE
AFTERNOON HOURS. WHILE SOUTHEASTERN AREAS COULD SEE ADDITIONAL
LIGHT ACCUMULATIONS...THE HEAVIEST SNOWFALL WILL HAVE ENDED. DID
LOWER POPS DURING THE AFTERNOON...BUT IT IS POSSIBLE THEY WILL
NEED TO BE LOWER EVEN MORE WITH A QUICKER EXIT OF PRECIPITATION.
DRY CONDITIONS REMAIN TUESDAY EVENING AND INTO WEDNESDAY IN THE
WAKE OF THIS LATEST SYSTEM...BUT IT IS A BRIEF BREAK IN THE
ACTION. CHANCES FOR SNOW MAKE A RETURN TO NORTHERN PORTIONS OF THE
CWA LATE WEDNESDAY NIGHT...AS A LOW PRESSURE SYSTEM SWINGS SOUTH
INTO THE CENTRAL ROCKIES WITH A TROUGH AXIS EXTENDING NORTHEAST
THROUGH WRN NEB AND THE DAKOTAS. ANY SNOWFALL WOULD LIKELY BE ON
THE LIGHT SIDE.
AS FAR AS TEMPERATURES GO...BETWEEN THE INCREASING CLOUD COVER AND
COOLER AIR FILTERING IN WITH BEHIND THE FRONT...NOT EXPECTING
BIG CHANGES THROUGH THE MORNING HOURS TODAY...AND SHOULD SEE HIGHS
BEFORE/NEAR MIDDAY BEFORE STARTING TO SEE TEMPS FALL OFF DURING
THE AFTERNOON. INTO TUESDAY...EVEN THOUGH PRECIPITATION WILL BE
COMING TO AN END DURING THE AFTERNOON...COOLER AIR REMAINING IN
PLACE IS EXPECTED TO KEEP HIGHS IN THE UPPER 20S TO LOWER 30S. AND
DEPENDING ON THE ACTUAL SNOWFALL THAT FALLS WITH THIS STORM
SYSTEM...SOME AREAS MAY NEED A DOWNWARD ADJUSTMENT. SHOULD SEE A
BUMP UP IN TEMPS ON WED WITH A MORE DOWNSLOPING COMPONENT TO THE
WINDS...WITH SNOW FREE AREAS POSSIBLY REACHING NEAR 40...WHILE
SOUTHEASTERN AREAS MAY STRUGGLE TO GET INTO THE MID 30S.
LONG TERM...THURSDAY THROUGH SUNDAY. AT THE ONSET OF THE EXTENDED
ON THURSDAY...COLD AIR WILL CONTINUE TO FILTER SOUTH FOLLOWING
COLD FRONTAL PASSAGE AS UPPER TROUGH CROSSES THE CENTRAL PLAINS.
FRONTOGENETIC FORCING AND LIFT IN UPPER DYNAMICS AS TROUGH SWINGS
THROUGH WILL PROVIDE CHCS FOR LIGHT SNOW NW/SE THURSDAY INTO
FRIDAY MORNING...AND HAVE FOLLOWED CLOSER TO OPEN WAVE ECMWF
SOLUTION VS GFS WHICH CLOSES THE LOW IN NORTHEAST KS THURSDAY
NIGHT. CONDITIONS STILL LOOK TO DRY OUT FOR THE HOLIDAY WEEKEND
WITH A BRIEF PERIOD OF HEIGHT RISES FRIDAY NIGHT/SATURDAY BEHIND
DEPARTING TROUGH. ANOTHER CLIPPER SYSTEM BRINGS IN ANOTHER ROUND
OF COLD AIR FOR CHRISTMAS DAY...WHILE A 100+KT JET DIVES ALONG THE
ROCKY MOUNTAIN REGION FURTHER CARVING A TROUGH ACROSS THE CENTRAL
PLAINS. GFS IS COLDER WITH TEMP PROFILE FOR CHRISTMAS THAN ECMWF
AND SUGGESTS HIGHS MAY ONLY BE IN THE 20S...BUT GIVEN UNCERTAINTY
ON DEGREE OF COLD AIR WILL FOLLOW CLOSER TO ENSEMBLE SOLUTIONS
WITH HIGHS DURING THROUGH THE EXTENDED PERIODS AVERAGING IN THE
LOWER 30S WITH LOWS MAINLY IN THE TEENS.
&&
.GID WATCHES/WARNINGS/ADVISORIES...
NE...NONE.
KS...WINTER WEATHER ADVISORY FROM 6 PM THIS EVENING TO 6 PM CST
TUESDAY FOR KSZ005>007.
WINTER STORM WARNING FROM 6 PM THIS EVENING TO 6 PM CST TUESDAY
FOR KSZ017>019.
&&
$$
UPDATE...BRYANT
SHORT TERM...ADO
LONG TERM...CF
AREA FORECAST DISCUSSION
NWS HASTINGS NE
1120 AM CST MON DEC 19 2011
.AVIATION...18Z TAF. IFR CEILINGS HAVE MOVED INTO PARTS OF SOUTH
CENTRAL NEBRASKA BEHIND A COLD FRONT THAT TRAVELED ACROSS THE
AREA EARLIER TODAY. THE GENERAL TREND HAS BEEN FOR THE IFR
CEILINGS TO LIFT TO MVFR...AND THIS IS ALSO SHOWN BY THE LATEST
NAM PROXIMITY SOUNDINGS..SO WILL ONLY CARRY THE LOWER CEILINGS IN
A BRIEF TEMPO GROUP. PROXIMITY SOUNDINGS ALSO SHOW THE MVFR
CEILINGS IMPROVING THIS AFTERNOON...THOUGH THE RUC IS FASTER IN
LIFTING THE CEILINGS THAN THE NAM. WILL AIM FOR MORE OF A
COMPROMISE SOLUTION AND GO WITH 21Z AS A START. WINDS WILL REMAIN
GUSTY AND FROM THE NORTH MOST OF THE AFTERNOON...BUT THEY SHOULD
DIMINISH THIS EVENING. THERE WILL BE CHANCES OF SNOW SOUTH OF
KGRI AS A STORM SYSTEM MOVES ACROSS THE CENTRAL AND SOUTHERN
PLAINS...BUT THINK THAT THE CHANCES WILL STAY FAR ENOUGH SOUTH TO
KEEP THE MENTION OUT OF THE FORECAST AT KGRI.
&&
.PREV DISCUSSION... /ISSUED 511 AM CST MON DEC 19 2011/
SHORT TERM...TODAY THROUGH WEDNESDAY NIGHT. PRIMARY FORECAST
CONCERN LIES WITH PRECIPITATION CHANCES TODAY THROUGH TUESDAY.
SEEING THE RELATIVE QUIET BEFORE THE STORM EARLY THIS
MORNING...BUT THE NEXT SYSTEM OF INTEREST IS QUITE EVIDENT ON
SATELLITE IMAGERY. THE MAIN UPPER LEVEL LOW PRESSURE SYSTEM TAKING
AIM ON THE PLAINS IS CURRENTLY SPINNING OVER SRN NEW
MEXICO...WHILE THE NORTHERN STREAM SHORTWAVE TROUGH ALSO AFFECTING
THE REGION CONTINUES TO SHIFT SOUTHEAST OUT OF CENTRAL CANADA AND
INTO THE DAKOTAS. AT THE SURFACE...THE COLD FRONT HAS BEEN MAKING
ITS WAY SOUTH OVERNIGHT...AND CURRENTLY IS DRAPED THROUGH THE
CENTRAL PORTIONS OF THE CWA...BRINGING NORTHWESTERLY WINDS BEHIND
IT...BUT THE MORE GUSTY WINDS ARE FOR THE TIME BEING LAGGING JUST
A BIT FURTHER NORTH. THE CWA IS ALSO SEEING INCREASED LOW TO MID
LEVEL MOISTURE AND CLOUD COVER STREAM NORTH FROM THE MAIN STORM
SYSTEM...WHILE LOW LEVEL STRATUS ACCOMPANYING THE SURFACE COLD
FRONT CONTINUES TO PUSH SOUTH AND WILL BE POKING INTO THE NORTHERN
CWA WITHIN THE NEXT HOUR.
THE MOST ACTIVE PERIOD IN THE SHORT TERM CONTINUES TO LIE ROUGHLY
BETWEEN MIDDAY TODAY THROUGH MIDDAY TUESDAY. THE NORTHERN STREAM
SHORTWAVE TROUGH MOVING THROUGH THE DAKOTAS WILL CONTINUE TO PUSH
THE SURFACE COLD FRONT FURTHER SOUTH INTO CENTRAL PORTIONS OF
KANSAS BY MIDDAY. THE UPPER LEVEL LOW PRESSURE SYSTEM WILL
CONTINUE TO PUSH EAST THROUGH NEW MEXICO THROUGH THE DAY...AND BY
LATE THIS EVENING IS EXPECTED TO BE CENTERED OVER THE PANHANDLE OF
TEXAS. THROUGH THE REMAINDER OF THE OVERNIGHT HOURS AND THROUGH
TUESDAY...THE SYSTEM WILL CONTINUE ITS NORTHEASTWARD
TREK...CROSSING THROUGH SOUTH CENTRAL AND EASTERN KANSAS...AND
LOOKS TO END UP NEAR THE KANSAS CITY AREA BY TUESDAY EVENING.
ISENTROPIC LIFT RAMPING UP OUT AHEAD OF THE SYSTEM WILL BRING
INCREASING PRECIPITATION CHANCES...ESPECIALLY STARTING THIS
AFTERNOON...WITH CHANCES CONTINUING OVERNIGHT AND INTO TUESDAY
WITH BETTER FRONTOGENETICAL FORCING AND WITH THE SYSTEM ITSELF
PASSES THROUGH THE REGION. MAIN CHANGES MADE TO THE FORECAST WERE
TO INCREASE POPS...MAINLY ACROSS NC KS. HOWEVER...EVEN THIS CLOSE
TO THE EVENT...SOME UNCERTAINTY EXISTS BECAUSE OF INCONSISTENCIES
BETWEEN MODELS. THE 00Z RUNS OF MANY MODELS DEPICTED A SLIGHT
NORTHWARD TREND TO THINGS...WHICH WAS CONCERNING FOR MORE OF THE
CWA...ONLY TO SEE THE 06Z RUNS STARTING TO PUSH THINGS BACK CLOSER
TO WHERE THEY WERE LAST NIGHT. BECAUSE OF THIS...DIDNT MAKE
SIGNIFICANT CHANGES TO POPS IN SC NEB...THOUGH CONFIDENCE IS NOT
HIGH IN JUST HOW FAR NORTH SNOW WILL ACTUALLY FALL. IF TRENDS FROM
CURRENT MODEL RUNS HOLD...FORECAST POPS ARE TOO FAR NORTH...BUT AT
THIS POINT DO HAVE LIGHT ACCUMULATIONS ALONG AND JUST NORTH OF
HIGHWAY 6.
DECIDED TO UPGRADE THE WATCH ACROSS THE SRN 3 COUNTIES TO A WINTER
STORM WARNING...THERE HAS BEEN MORE CONSISTENCY WITH MODELS
SHOWING THE GREATER QPF IN THOSE AREAS AND TO THE SOUTH...AND
FEEL THAT SOUTHERN PORTIONS OF THOSE COUNTIES COULD END UP SEEING
ARND 8 INCHES OF SNOW. STILL EXPECTING A SHARP GRADIENT WITH
PRECIPITATION AMOUNTS AS ONE GOES FURTHER NORTH...BUT THERE IS
STILL THE POTENTIAL FOR PHILLIPS/SMITH/JEWELL COUNTIES TO SEE 2 TO
6 INCHES OF SNOW /THE HIGHER AMOUNTS ARE EXPECTED TO BE IN JEWELL
COUNTY/...SO A WINTER WX ADV WAS ISSUED FOR THOSE COUNTIES.
CONSIDERED THROWING NUCKOLLS/THAYER IN AS WELL...BUT CURRENT
FORECAST TOTALS WERE ONLY IN THE 1 TO 3 RANGE. DAY SHIFT WILL HAVE
TO ASSESS 12Z RUNS TO SEE IF THEY DO NEED TO BE ADDED.
SOMETHING ELSE TO ADD TO THE SNOW CONCERN IS THE EXPECTED INCREASE
IN WINDS. WHILE THE MAIN FRONT WILL SHIFT SOUTH OF THE CWA...THE
APPROACHING STORM FROM THE SW WILL PREVENT IT FROM COMPLETELY
CLEARING THE AREA...AND WITH HIGH PRESSURE BUILDING IN FROM THE
NORTHWEST...IT WILL LEAD TO A TIGHTENING PRESSURE GRADIENT. THERE
IS EXPECTED TO BE AN INCREASE IN WINDS ACROSS THE CWA WITH THE
INITIAL FRONTAL PASSAGE...WITH THAT TIGHTER GRADIENT SETTING UP
THIS AFTERNOON AND EVENING. SPEEDS INCREASING TO 20 TO 30 MPH WITH
HIGHER GUSTS WILL BE COMMON ACROSS THE CWA...BUT NORTHERN AREAS
WILL START TO SEE SPEEDS TAPER OFF SOONER THAN SOUTHERN AREAS.
THESE SPEEDS STICKING AROUND LONGER IN THE SOUTH CORRESPONDS WITH
THE ONSET OF THE PRECIPITATION LATER TODAY/TONIGHT...WHICH WILL
RESULT IN SOME TRAVEL DIFFICULTIES DUE TO VISIBILITY RESTRICTIONS.
AS WE GET INTO TOMORROW...WILL START TO SEE PRECIPITATION
BEGINNING TO WIND DOWN...ESPECIALLY TOWARD MIDDAY AND INTO THE
AFTERNOON HOURS. WHILE SOUTHEASTERN AREAS COULD SEE ADDITIONAL
LIGHT ACCUMULATIONS...THE HEAVIEST SNOWFALL WILL HAVE ENDED. DID
LOWER POPS DURING THE AFTERNOON...BUT IT IS POSSIBLE THEY WILL
NEED TO BE LOWER EVEN MORE WITH A QUICKER EXIT OF PRECIPITATION.
DRY CONDITIONS REMAIN TUESDAY EVENING AND INTO WEDNESDAY IN THE
WAKE OF THIS LATEST SYSTEM...BUT IT IS A BRIEF BREAK IN THE
ACTION. CHANCES FOR SNOW MAKE A RETURN TO NORTHERN PORTIONS OF THE
CWA LATE WEDNESDAY NIGHT...AS A LOW PRESSURE SYSTEM SWINGS SOUTH
INTO THE CENTRAL ROCKIES WITH A TROUGH AXIS EXTENDING NORTHEAST
THROUGH WRN NEB AND THE DAKOTAS. ANY SNOWFALL WOULD LIKELY BE ON
THE LIGHT SIDE.
AS FAR AS TEMPERATURES GO...BETWEEN THE INCREASING CLOUD COVER AND
COOLER AIR FILTERING IN WITH BEHIND THE FRONT...NOT EXPECTING
BIG CHANGES THROUGH THE MORNING HOURS TODAY...AND SHOULD SEE HIGHS
BEFORE/NEAR MIDDAY BEFORE STARTING TO SEE TEMPS FALL OFF DURING
THE AFTERNOON. INTO TUESDAY...EVEN THOUGH PRECIPITATION WILL BE
COMING TO AN END DURING THE AFTERNOON...COOLER AIR REMAINING IN
PLACE IS EXPECTED TO KEEP HIGHS IN THE UPPER 20S TO LOWER 30S. AND
DEPENDING ON THE ACTUAL SNOWFALL THAT FALLS WITH THIS STORM
SYSTEM...SOME AREAS MAY NEED A DOWNWARD ADJUSTMENT. SHOULD SEE A
BUMP UP IN TEMPS ON WED WITH A MORE DOWNSLOPING COMPONENT TO THE
WINDS...WITH SNOW FREE AREAS POSSIBLY REACHING NEAR 40...WHILE
SOUTHEASTERN AREAS MAY STRUGGLE TO GET INTO THE MID 30S.
LONG TERM...THURSDAY THROUGH SUNDAY. AT THE ONSET OF THE EXTENDED
ON THURSDAY...COLD AIR WILL CONTINUE TO FILTER SOUTH FOLLOWING
COLD FRONTAL PASSAGE AS UPPER TROUGH CROSSES THE CENTRAL PLAINS.
FRONTOGENETIC FORCING AND LIFT IN UPPER DYNAMICS AS TROUGH SWINGS
THROUGH WILL PROVIDE CHCS FOR LIGHT SNOW NW/SE THURSDAY INTO
FRIDAY MORNING...AND HAVE FOLLOWED CLOSER TO OPEN WAVE ECMWF
SOLUTION VS GFS WHICH CLOSES THE LOW IN NORTHEAST KS THURSDAY
NIGHT. CONDITIONS STILL LOOK TO DRY OUT FOR THE HOLIDAY WEEKEND
WITH A BRIEF PERIOD OF HEIGHT RISES FRIDAY NIGHT/SATURDAY BEHIND
DEPARTING TROUGH. ANOTHER CLIPPER SYSTEM BRINGS IN ANOTHER ROUND
OF COLD AIR FOR CHRISTMAS DAY...WHILE A 100+KT JET DIVES ALONG THE
ROCKY MOUNTAIN REGION FURTHER CARVING A TROUGH ACROSS THE CENTRAL
PLAINS. GFS IS COLDER WITH TEMP PROFILE FOR CHRISTMAS THAN ECMWF
AND SUGGESTS HIGHS MAY ONLY BE IN THE 20S...BUT GIVEN UNCERTAINTY
ON DEGREE OF COLD AIR WILL FOLLOW CLOSER TO ENSEMBLE SOLUTIONS
WITH HIGHS DURING THROUGH THE EXTENDED PERIODS AVERAGING IN THE
LOWER 30S WITH LOWS MAINLY IN THE TEENS.
&&
.GID WATCHES/WARNINGS/ADVISORIES...
NE...NONE.
KS...WINTER WEATHER ADVISORY FROM 6 PM THIS EVENING TO 6 PM CST
TUESDAY FOR KSZ005>007.
WINTER STORM WARNING FROM 6 PM THIS EVENING TO 6 PM CST TUESDAY
FOR KSZ017>019.
&&
$$
AREA FORECAST DISCUSSION
NWS GRAND FORKS ND
1021 AM CST MON DEC 19 2011
.DISCUSSION...
THE CHALLENGE TODAY WILL BE CLOUD TRENDS AND TEMPS. A FAIRLY
EXPANSIVE CLOUD BAND WILL HANG TOUGH ACROSS NW MN AND NE ND
THROUGH TODAY...BEFORE SLOWLY DISSIPATING THIS EVENING AND
OVERNIGHT. THIS COUPLED WITH LIMITED MIXING SHOULD MEAN TEMPS
WON/T RISE TOO MUCH TODAY. EXPECT TEMPS TO WARM THE MOST IN THE SW
WHERE MORE SUNSHINE IS EXPECTED. WILL INCREASE SKY COVER...AND
TWEAK TEMPS UP A BIT MAINLY IN MN WHERE TEMPS ARE AT PROJECTED
HIGHS. OTHERWISE...THE REST OF THE FORECAST IS IN GOOD SHAPE
TODAY.
&&
.AVIATION...
MVFR STRATUS DECK EXTENDS WELL NORTH INTO CENTRAL MANITOBA AND WILL
CONTINUE TO SLIDE SOUTH-SOUTHEASTWARD THROUGH THE AFTERNOON. VALLEY
AIRFIELDS MAY BE NEAR THE CLEARING EDGE FOR MUCH OF THE AFTERNOON
WITH BRIEF PERIODS OF SCATTERED CEILINGS POSSIBLE. HOWEVER...A
RETURN TO PROLONGED VFR CONDITIONS NOT EXPECTED UNTIL MID-LATE
AFTERNOON AT THE EARLIEST FOR KGFK/KFAR AND AFTER 00 UTC AT KBJI.
LIGHT NORTHWEST WIND WILL SLOWLY SHIFT TO THE SOUTH OVERNIGHT.
&&
.PREV DISCUSSION... /ISSUED 235 AM CST MON DEC 19 2011/
DISCUSSION...FORECAST CHALLENGE CONCERNS MAINLY TEMPERATURES.
MODELS IN GOOD AGREEMENT. FOR PERSISTENCE WILL FOLLOW GFS FOR
DETAILS.
COLD ADVECTION CONTINUES EARLY THIS MORNING LEVELING OFF TOWARDS
LATE MORNING. COOLING HAS BEEN OFFSET BY MIXING AND CLOUD COVER.
CLOUDS LIKELY TO HOLD MINIMUMS UP THIS MORNING BUT WHEN CLOUDS BREAK
UP WILL DETERMINE HOW MUCH RECOVERY TODAY. RUC HOLDING IN LAYERED RH
THROUGH 18Z WITH GFS DRYING COLUMN DURING THE AFTERNOON AS HIGH
PRESSURE BUILDS IN. WILL BE RAISING MAX TEMPERATURES TODAY BASED ON
ANTICIPATED WARMER START. WITH LACK OF SNOW COVER AND LEVELING OFF
OF COLD ADVECTION ANY CLOUD BREAKS THIS AFTERNOON WILL ALLOW FOR A
MINOR TEMPERATURE RECOVERY.
HIGH PRESSURE WILL SAG SOUTH AND EAST OVERNIGHT INTO TUESDAY. THIS
WILL EVENTUALLY SET UP RETURN FLOW AND MODEST WARM ADVECTION FOR
TUESDAY. SKIES SHOULD CLEAR OFF ALONG WITH DIMINISHING WIND TONIGHT.
AGAIN LACK OF SNOW COVER WILL AFFECT MINIMUM TEMPERATURES AND STAY
WARMER THAN GUIDANCE. TRENDS CONTINUE TUESDAY WILL MAINTAIN MAXIMUM
TEMPERATURES WELL ABOVE GUIDANCE WITH LACK OF ANY SNOW COVER AND
ANTICIPATED SOLAR.
WEAK SURFACE TROUGH WILL CROSS FA TUESDAY NIGHT HOWEVER MOISTURE
LOOKS LIMITED SO WILL DROP LOW END POPS.
MID LEVEL FLOW REMAINS SPLIT WITH UPPER LOW CURRENTLY ACROSS DESERT
SW TRACKING EAST WELL SOUTH OF FA ON WEDNESDAY. ANY NORTHERN STREAM
MID LEVEL SUPPORT LOOKS WEAK HOWEVER WITH BAROCLINIC ZONE DROPPING
THROUGH FA COULD SEE SOME PATCHY -SN OR FLURRIES. WITH SPOTTY NATURE
OF MODEL QPF WILL NOT MAKE ANY MODIFICATIONS TO CURRENT SLIGHT
CHANCE POPS.
LONG TERM (THU-SUN)...
MODELS IN GOOD AGREEMENT WITH THE EXTENDED PATTERN... INDICATING
LITTLE CHANGE TO THE ONGOING OVERALL DRY PATTERN WITH WIDE
TEMPERATURE SWINGS AS SHORT WAVES TRAVERSE THE REGION. A SEASONABLY
COOL AIRMASS IN PLACE ON THURSDAY WILL LEAD TO NEAR NORMAL HIGHS AND
TRANSITION QUICKLY AS 500MB RIDGING BUILDS INTO THE NORTHERN PLAINS
WITH WAA OCCURS DURING THE DAY FRIDAY AND THE FIRST HALF OF
SATURDAY. THE ONLY PRECIP IN THE EXTENDED LOOKS TO BE FROM A COLD
FRONT SATURDAY NIGHT THAT MAY BRING A DUSTING OF SNOW TO THE AREA.
&&
.FGF WATCHES/WARNINGS/ADVISORIES...
ND...NONE.
MN...NONE.
&&
$$
DK
AREA FORECAST DISCUSSION
NWS HOUSTON/GALVESTON TX
350 PM CST MON DEC 19 2011
.DISCUSSION...
A STRONG UPPER LEVEL LOW PRESSURE SYSTEM CONTINUES PUSHING
NORTHEASTWARD INTO THE TEXAS PANHANDLE THIS AFTERNOON. AHEAD OF
THIS SYSTEM SHOWERS AND THUNDERSTORMS CONTINUE TO INCREASE IN
COVERAGE ACROSS CENTRAL AND NORTH TEXAS...WITH THIS ACTIVITY
EXTENDING SOUTHWARD INTO OUR NORTHWESTERN COUNTIES. THIS ACTIVITY
SHOULD CONTINUE TO INCREASE IN COVERAGE ACROSS OUR WESTERN
COUNTIES THIS AFTERNOON BEFORE A BROKEN LINE OF THUNDERSTORMS
PUSHES EASTWARD THROUGH THE REGION THIS EVENING. LATEST RUNS OF
THE HRRR AND LOCAL WRF MODELS CONTINUE TO SUGGEST THE STRONGEST
ACTIVITY WILL DEVELOP ACROSS OUR NORTHERN COUNTIES LATER THIS
EVENING AND PUSH EASTWARD OUT OF THE REGION BY AROUND MIDNIGHT.
SCATTERED SHOWERS AND THUNDERSTORMS MAY LINGER ACROSS OUR EASTERN
AND COASTAL COUNTIES THROUGH DAYBREAK ON TUESDAY BEFORE THE
PACIFIC COLD FRONT PUSHES THROUGH THE REGION. OUR NEXT CHANCE FOR
RAIN WILL COME WEDNESDAY NIGHT INTO THURSDAY MORNING AS ANOTHER
UPPER LEVEL TROUGH MOVES THROUGH THE PANHANDLE. STRONG ISENTROPIC
LIFT WILL EXIST ACROSS THE REGION ALONG WITH UPPER LEVEL SUPPORT
IN THE FORM OF A RIGHT ENTRANCE REGION OF THE UPPER JET.
PRECIPITATION SHOULD COME TO AN END FAIRLY EARLY THURSDAY
AFTERNOON AS THE SYSTEM MOVES RAPIDLY OUT OF THE REGION.
MODELS CONTINUE TO HAVE SOME DIFFICULTY WITH THE TIMING OF THE
NEXT WEATHER SYSTEM WHICH WILL AFFECT THE REGION OVER THE HOLIDAY
WEEKEND. LATEST MODEL RUNS HAVE TRENDED DRIER FOR THE WEEKEND BUT
AM HESITANT TO REMOVE POPS WITH THE UPPER TROUGH AXIS REMAINING TO
OUR WEST. WILL KEEP SLIGHT CHANCE POPS IN PLACE FOR CHRISTMAS DAY
FOR NOW. 38
&&
.PRELIMINARY POINT TEMPS/POPS...
COLLEGE STATION (CLL) 71 53 61 38 60 / 50 80 10 10 10
HOUSTON (IAH) 72 62 68 43 62 / 20 80 20 10 10
GALVESTON (GLS) 71 63 70 50 62 / 20 60 30 10 10
&&
.HGX WATCHES/WARNINGS/ADVISORIES...
TX...NONE.
GM...SMALL CRAFT SHOULD EXERCISE CAUTION UNTIL 9 PM CST THIS EVENING
FOR THE FOLLOWING ZONES: MATAGORDA BAY...WATERS FROM
FREEPORT TO THE MATAGORDA SHIP CHANNEL OUT 20 NM.
SMALL CRAFT SHOULD EXERCISE CAUTION UNTIL MIDNIGHT CST TONIGHT
FOR THE FOLLOWING ZONES: GALVESTON BAY...WATERS FROM HIGH
ISLAND TO FREEPORT OUT 20 NM.
SMALL CRAFT ADVISORY UNTIL 6 AM CST TUESDAY FOR THE FOLLOWING
ZONES: WATERS FROM HIGH ISLAND TO FREEPORT 20 TO 60 NM.
SMALL CRAFT ADVISORY UNTIL 9 PM CST THIS EVENING FOR THE
FOLLOWING ZONES: WATERS FROM FREEPORT TO THE MATAGORDA SHIP
CHANNEL 20 NM TO 60 NM.
&&
$$
DISCUSSION...38
AVIATION/MARINE...45
AREA FORECAST DISCUSSION...UPDATED
NWS FORT WORTH TX
1152 AM CST MON DEC 19 2011
.AVIATION...
18Z TAF CONCERNS...
TIMING OF MAIN BAND OF TSRA AND CIG TRENDS...AS WELL AS WIND
SHIFTS REGARDING SURFACE TROUGH...THEN COLD FRONT TUES MORNING.
PER LATEST MODEL SOUNDINGS...MID AFTERNOON THROUGH SUNSET FOR THE
MAIN BAND OF STORMS TO MOVE THROUGH. WILL SKEW EASTERN METRO TAFS
AN HOUR LATER FROM WESTERN METRO TAFS ON TIMING TSRA/CIGS/AND
ARRIVAL OF SURFACE BOUNDARIES THROUGH TONIGHT. WACO TIMING WILL BE
SIMILAR TO WESTERN METRO AIRPORTS WITH PREVAILING MVFR AND SOONER
ARRIVAL OF SHRA/TSRA.
SHOULD SEE SURFACE TROUGH ARRIVE MID-LATE EVENING WITH WINDS
VEERING AND SPEEDS LOWERING WITH VFR CONDITIONS. COLD FRONT
ARRIVES IN MID-LATE MORNING PERIOD TUESDAY WITH WINDS VEERING WNW
15G25 KTS. WRAP AROUND MVFR CIGS FOR D/FW AIRPORTS TUES
MORNING...SLOWLY RISING TO LOW VFR WITH DEEPENING COLD AIR
ADVECTION BY MIDDAY TUES/AFTER.
05/
&&
.UPDATE...
LATEST WATER VAPOR IMAGERY SHOWS THE LARGE UPPER LOW CONTINUING TO
SLOWLY MOVE EAST THIS MORNING AND MAY NOW BE STARTING TO SHIFT TO
THE NORTH. THIS CONTINUED EASTWARD MOVEMENT OVERNIGHT WASNT
FORECASTED BY THE MODELS AND THE OVERALL TRACK OF THE UPPER LOW
AND SUBSEQUENT SURFACE LOW WILL BE A BIT FURTHER SOUTH THAN
ANTICIPATED. A LEAD VORTICITY LOBE HAS DETACHED FROM THIS TROUGH
AND A BAND OF THUNDERSTORMS HAVE DEVELOPED WITHIN THIS SMALL AREA
OF ENHANCED LIFT THIS MORNING JUST WEST OF THE FORECAST AREA.
EXPECT THIS AREA OF SHOWERS AND THUNDERSTORMS TO CONTINUE TO MOVE
TO THE NE AND IT COULD AFFECT OUR NORTHWESTERN ZONES LATER THIS
MORNING.
16Z SURFACE ANALYSIS CONTINUES TO SHOW MOISTURE STREAMING
NORTHWARD. 60 DEWPOINTS ARE NOW JUST SOUTHWEST OF THE CWA AND
SHOULD SEE THESE VALUES IN OUR CWA SHORTLY. A WARM FRONT IS
ANALYZED ACROSS THE SOUTHWESTERN ZONES AND THIS BOUNDARY IS
EXPECTED TO MOVE NORTHEAST WITH THE SURFACE LOW.
THE SET UP FOR SEVERE WEATHER THIS AFTERNOON AND EVENING CONTINUES
TO COME TOGETHER...BUT THERE ARE STILL SEVERAL FACTORS THAT HAVE
TO PLAY OUT IN THE NEXT 4-6 HOURS TO DETERMINE THE OVERALL CHANCES
FOR SEVERE THUNDERSTORMS. THE LARGE AREA OF PRECIP TO OUR WEST
CONTINUES TO SLOWLY MOVE TO THE EAST AND WOULDNT BE SURPRISED TO
SEE SCATTERED SHOWERS AND THUNDERSTORMS WEST OF INTERSTATE 35 IN
THE LATE MORNING AND EARLY AFTERNOON HOURS AS THE LEAD IMPULSE
MOVES NEAR THE AREA. EXPECT THAT WE WOULD HAVE SOME TIME BETWEEN
THIS LEAD PRECIP AND WHEN THE LINE OF THUNDERSTORMS MOVES THROUGH
THE AREA IN THE LATE AFTERNOON AND EVENING HOURS. WITH A 50-60
KNOT LOW LEVEL JET IN PLACE...THE AIRMASS SHOULD BE ABLE TO
QUICKLY RECOVER FROM ANY LINGERING EFFECTS OF PRECIPITATION.
THE SECOND FACTOR WILL BE THE AVAILABLE INSTABILITY IN PLACE THIS
AFTERNOON. THE 12Z NAM SEEMS TO HAVE THE BEST HANDLE REGARDING
SURFACE T/TD AND INSTABILITY VALUES. EXPECT THE 60 DEWPOINT
ISODROSOTHERM TO BE AS FAR NORTH AS HILL COUNTY BY 21Z AND INTO
THE METROPLEX BY 00Z THIS EVENING. WE SHOULD SEE SOME SURFACE CAPE
WITH THE 60 DEWPOINTS...BUT HIGHER VALUES NEAR 1000 J/KG WILL BE
CONFINED TO AREAS WITH 63+ DEWPOINTS...LOCATED TO THE SOUTH OF
WACO. THESE LOCATIONS WILL SEE THE BEST CHANCES OF SEVERE
WEATHER.
THE THIRD FACTOR WILL BE THE STORM MODE. LATEST HIGH RESOLUTION
MODEL OUTPUT FORMS A SOLID LINE OF CONVECTION IN OUR WESTERN ROW OF
COUNTIES NEAR 19Z OR 1 PM AS STRONG FRONTOGENETICAL FORCING
DEVELOPS ALONG THE EASTWARD MOVING FRONTAL BOUNDARY. THERE ARE
SOME HINTS IN THE MODEL OUTPUT THAT AS THE LINE MOVES EAST THERE
MAY BE SOME BREAKS IN THE LINE AND SEPARATE STORM SEGMENTS WOULD
BE THE DOMINANT MODE. IF THIS WERE TO OCCUR...THE POTENTIAL
FOR TORNADOES WOULD INCREASE AS THESE SEGMENTS WOULD LIKELY BE
SUPERCELLS GIVEN THE STRONG SHEAR IN PLACE. LOCATIONS SOUTH AND
EAST OF A KILLEEN TO DFW TO PALESTINE LINE HAVE THE BEST CHANCES
FOR A TORNADO TODAY PER LATEST SPC DAY 1 OUTLOOK. THESE LOCATIONS
WILL HAVE THE BEST LOW-LEVEL INSTABILITY THIS AFTERNOON...BUT
AGAIN...THE FURTHER SOUTH YOU ARE...THE BETTER CHANCE FOR A
TORNADO. TEMPERATURE/DEWPOINT FIELDS WILL NEED TO BE WATCHED
CLOSELY TODAY AS A FEW DEGREES OFF OF FORECASTED VALUES EITHER WAY
COULD HAVE A BIG IMPACT ON THE SEVERE/TORNADO POTENTIAL.
85/NH
&&
.PREV DISCUSSION... /ISSUED 412 AM CST MON DEC 19 2011/
POWERFUL UPPER LEVEL LOW NEAR EL PASO WILL BEGIN TO CURVE NORTH
AND TRACK ACROSS THE TX PANHANDLE TONIGHT. STORM SYSTEM WILL BE
RESPONSIBLE FOR BLIZZARD CONDITIONS OVER THE SOUTHERN HIGH PLAINS
AND A ROUND OF STORMS WITH A POTENTIAL FOR SEVERE WEATHER HERE.
THIS UPPER LOW IS VERY STRONG AND HAS SIMILARITIES TO THE DEC 29
2006 SYSTEM THAT PRODUCED 22 TORNADOES IN OUR CWA. ALTHOUGH WE DO
NOT EXPECT AN EVENT OF THAT MAGNITUDE THIS TIME DUE TO A FARTHER
NORTH POSITION OF THE WARM FRONT AND LESS UNSTABLE AIR OVER OUR
REGION...IT DOES HEIGHTEN OUR AWARENESS FOR SEVERE WEATHER.
SUBSTANTIAL HEIGHT FALLS ARE ALREADY RESULTING IN 3HR PRESSURE
FALLS OF 3-5 MB ACROSS MUCH OF WEST TX. SOUTHERLY WINDS THROUGH
THE TROPOSPHERE ARE INCREASING...AND WILL CONTINUE TO DO SO DURING
THE DAY. WIND SHEAR WILL BECOME VERY STRONG WITH 0-6KM SHEAR NEAR
60KT AND 0-3KM HELICITY AT OR ABOVE 500 M2/S2. SOUTHERLY 850 MB
WINDS ARE EXPECTED TO REACH 60KT BY NOON...AIDING IN THE TRANSPORT
OF WARM/MOIST AIR INTO THE CWA. RAPID AIR MASS MODIFICATION IS
EXPECTED DURING THE NEXT 12 HOURS...WITH DEWPOINTS LIKELY RISING
INTO THE LOW 60S...WITH SOME MID 60S ACROSS THE SOUTH CENTRAL CWA.
STRONG MOISTURE ADVECTION SHOULD KEEP SKIES CLOUDY...AND HIGH
TEMPS SHOULD BE HELD IN THE MID-UPPER 60S...HELPING TO LIMIT
INSTABILITY. THE PRIMARY INHIBITING FACTOR FOR SEVERE WEATHER AND
THE MOST UNCERTAIN PART OF THIS FORECAST IS THE INSTABILITY. GIVEN
THE NATURE OF THIS DYNAMIC SYSTEM AND ANALOGS TO PAST COOL SEASON
SEVERE WEATHER PRODUCING SYSTEMS...WILL CONTINUE TO FAVOR THE NAM
WHICH IS MOST AGGRESSIVE WITH INSTABILITY. EXPECT SB CAPE TO REACH
1000 J/KG OVER THE SOUTH CENTRAL ZONES...WITH VALUES TAPERING OFF
TO 500 J/KG NEAR THE I-20 CORRIDOR. IT IS IMPORTANT TO NOTE THAT
ABOUT 250 J/KG OF THE TOTAL CAPE RESIDES BELOW 3KM...WHICH IS VERY
HIGH FOR ANYTIME OF THE YEAR...AND INCREASES THE POTENTIAL FOR
VORTEX STRETCHING NEAR THE GROUND AND TORNADOGENESIS.
MOST OF THE STORMS WILL FORM ALONG A NORTH-SOUTH ORIENTED COLD
FRONT THAT WILL REACH THE WESTERN CWA IN THE EARLY AFTERNOON.
AHEAD OF THE FRONT...THERE WILL BE SOME WARM ADVECTION SHOWERS
STREAMING UP FROM THE SOUTH. CONVECTION AHEAD OF THE FRONT MAY BE
DISCRETE...BUT INSTABILITY MAY NOT YET BE HIGH ENOUGH FOR ANYTHING
MORE THAN SHOWERS UNTIL FRONTOGENETIC FORCING ARRIVES WITH THE
FRONT. STORM MOTION IS EXPECTED TO BE AT 45KT AND THIS SUGGESTS
DAMAGING WINDS WILL BE THE PRIMARY SEVERE WEATHER THREAT DUE TO
DOWNWARD MOMENTUM TRANSPORT. BECAUSE STORMS SHOULD FORM INTO A
LINE ALONG THE FRONT...TORNADO POTENTIAL SHOULD BE LIMITED...BUT
CONDITIONS ARE STILL FAVORABLE FOR ISOLATED BRIEF SPIN-UPS WITHIN
THE LINE. SEVERE WEATHER THREAT EXISTS JUST ABOUT EVERYWHERE...BUT
WILL BE HIGHEST ALONG THE I-35 CORRIDOR SOUTH OF I-20 WHERE BAND
OF INSTABILITY WILL BE HIGHEST. THERE IS SOME UNCERTAINTY WITH THE
TIMING...AS THE HRRR IS THE QUICKEST...AND THE NAM ABOUT 5 HOURS
SLOWER. THE ECMWF OFFERS A GOOD COMPROMISE AND EXPECT THE SQUALL
LINE TO IMPACT THE WESTERN ZONES 2-6PM...THE I-35 CORRIDOR
4-8PM...AND MOVE OUT OF THE EASTERN ZONES BY 12AM.
WINDY AND COLDER CONDITIONS ARE EXPECTED TUESDAY AS COLD AIR POURS
IN BEHIND THE CYCLONE. SOME WRAP AROUND CLOUDS WILL AFFECT THE
NORTHERN ZONES. WINDS DIMINISH TUESDAY NIGHT...WITH SUBFREEZING
TEMPS OVER MOST OF THE CWA. NEXT UPPER LEVEL SHORTWAVE WILL
APPROACH WEDNESDAY...WITH INCREASING MID-HIGH CLOUDS. MOISTURE
APPEARS SUFFICIENT FOR A LOW CHANCE OF RAIN OVER THE SOUTHEAST
HALF OF THE AREA WED NIGHT AND THURSDAY MORNING. ONCE THIS IMPULSE
MOVES THROUGH...ANOTHER COLD FRONT WILL ARRIVE THURSDAY EVENING.
EXTENDED FORECAST REMAINS OF VERY LOW CONFIDENCE DUE TO WIDESPREAD
DISAGREEMENT IN HOW SEVERAL VORT LOBES INTERACT WITH EACH OTHER.
REGARDLESS OF THE DETAILS...THE SYNOPTIC PATTERN SUGGESTS WITH
HIGH CONFIDENCE THAT IT WILL BE COLD FOR THE HOLIDAY WEEKEND. WILL
NEED BETTER INTER-MODEL AND RUN-TO-RUN CONSISTENCY BEFORE
ENTERTAINING THE POTENTIAL FOR PRECIPITATION.
TR.92
&&
.PRELIMINARY POINT TEMPS/POPS...
DALLAS-FT. WORTH, TX 63 44 50 31 53 / 100 90 5 0 5
WACO, TX 67 43 53 29 54 / 90 90 5 0 10
PARIS, TX 62 49 56 30 51 / 50 100 10 0 5
DENTON, TX 62 42 47 27 52 / 100 80 10 0 5
MCKINNEY, TX 63 44 49 28 52 / 90 100 10 0 5
DALLAS, TX 64 45 51 33 53 / 90 100 5 0 5
TERRELL, TX 65 47 53 32 52 / 80 100 5 0 5
CORSICANA, TX 68 47 55 33 54 / 70 100 10 0 10
TEMPLE, TX 68 43 55 31 55 / 90 90 5 0 10
MINERAL WELLS, TX 61 39 46 26 53 / 100 40 10 0 5
&&
.FWD WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
05/85
AREA FORECAST DISCUSSION...UPDATED
NWS CORPUS CHRISTI TX
1108 AM CST MON DEC 19 2011
.DISCUSSION...PACIFIC FRONT CURRENTLY ENTERING EXTREME NW CWA.
CLEARING SKIES ACROSS REST OF S TX ARE ALLOWING FOR STRONG MIXING
OF UNSEASONABLY STRONG 45 TO 55 KT LLJ TO MIX TO SFC. GUSTS OVER
40 MPH HAVE ALREADY OCCURRED AT ALICE AND BEEVILLE AND HAVE
EXPANDED WIND ADVISORY FOR REST OF EASTERN HALF OF CWA. HAVE ALSO
INCREASED HIGHS ACROSS THE BOARD DUE TO ADDITIONAL SUNSHINE AND
STRONG SRLY WINDS. HAVE REMOVED MENTION OF WX ACROSS MOST ZONES
UNTIL LATE THIS AFTERNOON. LATEST HRRR AND 4KM WRF INDICATE NARROW
BAND OF PRECIP MAY DEVELOP ACROSS EASTERN ZONES BY MID TO LATE
AFTERNOON AND THEN INTENSIFY OVER MARINE AREAS. STRONGEST CONVECTION
MAY REMAIN TO THE NORTHEAST OF CWA.
&&
.PRELIMINARY POINT TEMPS/POPS...
CORPUS CHRISTI 79 60 68 44 62 / 30 40 20 10 10
VICTORIA 76 56 64 39 61 / 50 50 10 10 10
LAREDO 76 50 66 44 65 / 10 10 0 0 10
ALICE 83 57 67 43 64 / 20 30 10 10 10
ROCKPORT 74 61 68 47 61 / 40 50 20 10 10
COTULLA 75 45 65 39 64 / 20 10 0 0 10
KINGSVILLE 82 58 69 44 64 / 20 30 20 10 10
NAVY CORPUS 76 62 67 49 62 / 30 40 20 10 10
&&
.CRP WATCHES/WARNINGS/ADVISORIES...
TX...WIND ADVISORY UNTIL 4 PM CST THIS AFTERNOON FOR THE FOLLOWING
ZONES: ARANSAS...BEE...CALHOUN...GOLIAD...JIM WELLS...
KLEBERG...LIVE OAK...NUECES...REFUGIO...SAN PATRICIO...
VICTORIA.
GM...SMALL CRAFT ADVISORY UNTIL MIDNIGHT CST TONIGHT FOR THE
FOLLOWING ZONES: COASTAL WATERS FROM BAFFIN BAY TO PORT
ARANSAS OUT 20 NM...COASTAL WATERS FROM PORT ARANSAS TO
MATAGORDA SHIP CHANNEL OUT 20 NM...WATERS FROM BAFFIN BAY
TO PORT ARANSAS FROM 20 TO 60 NM...WATERS FROM PORT ARANSAS
TO MATAGORDA SHIP CHANNEL FROM 20 TO 60 NM.
SMALL CRAFT ADVISORY FOR WINDS UNTIL 6 PM CST THIS EVENING FOR
THE FOLLOWING ZONES: BAYS AND WATERWAYS FROM BAFFIN BAY TO
PORT ARANSAS...BAYS AND WATERWAYS FROM PORT ARANSAS TO PORT
O`CONNOR.
&&
$$
UPDATE...HART/79
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
246 PM CST MON DEC 19 2011
.SHORT TERM...THROUGH WEDNESDAY NIGHT
246 PM CST MON DEC 19 2011
MAIN FORECAST CONCERN IS WITH THE PRECIPITATION CHANCES AND TYPES
TUESDAY AND TUESDAY NIGHT.
SURFACE ANALYSIS THIS AFTERNOON SHOWS A NEARLY STATIONARY FRONT
FROM LOWER MICHIGAN TO AN AREA OF LOW PRESSURE OVER EASTERN NEW
MEXICO. HIGH PRESSURE WAS CENTERED OVER THE WESTERN DAKOTAS AND
EASTERN MONTANA.
STRATUS CLOUDS HAVE COME IN BEHIND THE COLD FRONT AND COVERED
ALMOST THE ENTIRE AREA THIS AFTERNOON. VISIBLE SATELLITE DOES
SHOW QUITE A FEW HOLES IN THE CLOUD FIELD AND THE CLOUDS ALSO
APPEAR TO BE THINNING OUT. THE 19.12Z NAM BUFKIT SOUNDINGS WOULD
SUGGEST THE CLOUDS SHOULD SCATTER OUT THIS EVENING WHILE SEVERAL
RUNS NOW OF THE RUC DO NOT SCATTER THE CLOUDS OUT UNTIL THE
OVERNIGHT HOURS. HAVE TRIED TO BALANCE THESE MODEL TRENDS WITH THE
CURRENT SATELLITE TRENDS TO SHOW CLEARING THROUGH THE EVENING FOR
MOST OF THE AREA. THIS WILL ALSO HAVE A BIG IMPACT ON THE
TEMPERATURES. HAVE BUMPED THE TEMPERATURES UP SOME...ESPECIALLY
ACROSS THE NORTH WHERE THE CLOUDS MAY HOLD ON THE LONGEST...BUT IF
THEY CLEAR OUT EARLIER THAN EXPECTED...THESE WILL HAVE TO BE MOVED
DOWN.
THE STORM SYSTEM OVER THE SOUTHWEST WILL BE EJECTING NORTHEAST
TOWARD THE OHIO RIVER VALLEY AND EASTERN GREAT LAKES FOR TUESDAY
THROUGH WEDNESDAY. AFTER A NORTHWARD JOG IN THE TRACK OF THIS
SYSTEM WITH YESTERDAY/S MODELS...ALL THE 19.12Z MODELS HAVE
SETTLED BACK SOUTH WITH THE TRACK. IT ONCE AGAIN APPEARS THAT THE
SOUTHERN PARTS OF THE AREA WILL EITHER GET BRUSHED WITH THIS SYSTEM
OR IT WILL JUST MISS TO THE SOUTH. THE NAM AND GFS STILL SHOW
DECENT FORCING WITH THIS SYSTEM JUST GOING BY TO THE SOUTH.
BETWEEN 4 AND 8 PVU/S OF VORTICITY ADVECTION IN THE 500-300 MB
LAYER PASSES BY TUESDAY AFTERNOON AND NIGHT. THE BEST QG
CONVERGENCE IS EXPECTED TO MISS THE AREA WITH JUST SOME WEAK
CONVERGENCE IN THE 700-500 MB LAYER COMING THROUGH TUESDAY NIGHT.
STILL EXPECTING TO SEE SOME WEAK FRONTOGENESIS IN THE 850-500 MB
LAYER AS WELL. ONE THING THAT HAS NOT CHANGED IN THE MODELS...IS
WHETHER THERE WILL BE ICE PRESENT IN THE CLOUDS. BUFKIT SOUNDINGS
ACROSS THE FAR SOUTH CONTINUE TO SUGGEST CLOUD TOP TEMPERATURES
ONLY AROUND -10C WHICH COULD LEAD TO MORE LIQUID INSTEAD OF SNOW.
HAVE CONTINUED WITH THE MIX OF FREEZING RAIN/RAIN AND SNOW BUT
WITH ONLY LIGHT PRECIPITATION AMOUNTS ANTICIPATED...ANY SNOW OR
ICE ACCUMULATIONS WILL BE VERY LIGHT.
ONCE THIS SYSTEM GOES BY...A NORTHERN STREAM SHORT WAVE TROUGH
WILL MOVE ALONG THE CANADIAN BORDER WEDNESDAY NIGHT. THIS WAVE
WILL PUSH A COLD FRONT INTO THE AREA THAT COULD POSSIBLY PRODUCE
SOME LIGHT SNOW AND HAVE CONTINUED WITH THE LOW END SNOW CHANCES
ACROSS THE NORTH WITH THIS SYSTEM.
.LONG TERM...THURSDAY THROUGH MONDAY
246 PM CST MON DEC 19 2011
THE COLD FRONT WILL CONTINUE TO PUSH SOUTH ACROSS THE REMAINDER OF
THE AREA THURSDAY AND COULD STILL BE PRODUCING SOME LIGHT SNOW.
ADDED IN SOME LOW END SNOW CHANCES TO HANDLE THIS POSSIBILITY.
ONCE THIS SYSTEM GOES BY...THE REMAINDER OF THE PERIOD LOOKS TO BE
PRETTY QUIET. ANOTHER NORTHERN STREAM WAVE COULD BRUSH THE UPPER
MIDWEST CHRISTMAS DAY AND HAVE CONTINUED WITH THE LOW SNOW CHANCES
ACROSS THE NORTHERN PART OF THE FORECAST AREA AS THE BEST FORCING
WITH THIS WAVE LOOKS TO REMAIN TO THE NORTH OF THE AREA.
&&
.AVIATION...THROUGH 18Z TUESDAY
1141 AM CST MON DEC 19 2011
EXPANSIVE FIELD OF POST-FRONTAL MVFR STRATOCUMULUS IN PLACE ACROSS
THE REGION. LATEST MODELS INDICATE THIS CLOUDS COVER SHOULD BREAK
UP/SCATTER OUT AROUND 00Z AS A RIDGE OF HIGH PRESSURE SETTLES
OVERHEAD. LIGHT/VARIABLE WINDS OVERNIGHT AND RADIATIONAL COOLING
COMBINED WITH A SOMEWHAT MOIST LOWER BOUNDARY LAYER MAY LEAD TO
SOME 3-5SM BR AT THE KRST/KLSE TAF SITE IN THE 11-14Z TIME FRAME.
CIRRUS/HIGHER LEVEL ALTOCUMULUS SHIELD LOOKS TO MOVE INTO PORTIONS
OF NORTHEAST IA/FAR SOUTHWEST WISCONSIN THROUGH THE REMAINDER OF
TUESDAY...BUT REMAINING VFR AT KLSE/KRST.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
246 PM CST MON DEC 19 2011
WI...NONE.
MN...NONE.
IA...NONE.
&&
$$
SHORT TERM...04
LONG TERM...04
AVIATION...DAS
AREA FORECAST DISCUSSION...UPDATED
NWS MILWAUKEE/SULLIVAN WI
1159 AM CST MON DEC 19 2011
.UPDATE...MOSTLY CLEAR SKIES IN FAR SOUTH AND SOUTHEAST PARTS OF
CWA HAVE ALLOWED TEMPS TO RISE INTO THE 40S. SURFACE OBS SHOW
STEADY OR SLIGHTLY FALLING TEMPS UNDER STRATUS DECK GRADUALLY
ENTERING SOUTHERN WISCONSIN. EXPECT FURTHER WARMING TO BE OFFSET
BY COLD AIR ADVECTION IN WAKE OF EARLIER FROPA...AND GIVEN THE
TEMP TRENDS UPSTREAM...THINK TEMPS HAVE PEAKED IN THE
NORTHWEST...AND WILL PEAK AT MIDDAY SOUTH AND EAST.
&&
.AVIATION/18Z TAFS/...LARGE AREA OF STRATUS IS CURRENTLY PUSHING
SOUTHEAST THROUGH THE FORECAST AREA BEHIND THE EXITING COLD FRONT.
STRATUS SHOULD REACH ILLINOIS BORDER BY MID AFTERNOON...WITH
CLOUDS THEN LINGERING THROUGH AT LEAST EVENING. THE FLOW WILL TURN
ONSHORE LATER TODAY...WITH SFC TO 850 MB DELTA T VALUES INCREASING
TO AROUND 14C. THUS EXPECTING LOW CLOUDS TO STICK AROUND IN THE
EAST THROUGH THE NIGHT. FARTHER WEST...MODELS SHOWING SOME DRYING
IN THE LOW LEVELS...SO WENT BACK TO VFR AT MSN TOWARD MIDNIGHT.
STRATUS FIELD IS QUITE EXPANSIVE THOUGH...SO WILL HAVE TO WATCH
SATELLITE TRENDS. WOULD NOT BE SURPRISED IF CLOUDS HANG ON IN THE
WEST LONGER THAN CURRENTLY EXPECTED.
UNLESS THE STRATUS IS STILL LINGERING...SHOULD SEE MAINLY HIGH
CLOUDS TUESDAY LOWERING THROUGH THE AFTERNOON AS LOW PRESSURE
APPROACHES FROM THE SOUTHWEST. MAY SEE SOME LIGHT RAIN OR SNOW
APPROACH THE IL/WI BORDER BY EVENING...BUT MOST MODELS KEEP PRECIP
SOUTH OF THE BORDER UNTIL LATER IN THE EVENING OR OVERNIGHT.
&&
.PREV DISCUSSION... /ISSUED 327 AM CST MON DEC 19 2011/
TODAY AND TONIGHT...FORECAST CONFIDENCE MEDIUM TO HIGH.
MID/UPPER JET MAX ACROSS THE NORTHERN GREAT LAKES TAKES THE MID
LEVEL SHORTWAVE AND ASSOCIATED LOW NORTHEAST OF LAKE
SUPERIOR...OFF TO THE EAST THIS MORNING...WITH A WEAK MID LEVEL
TROUGH AXIS PUSHING DOWN ACROSS SOUTHERN WISCONSIN TONIGHT.
850MB THERMAL RIDGE WILL EXTEND ACROSS SOUTHERN WISCONSIN EARLY
THIS MORNING. RUC SOUNDINGS INDICATE THAT THE 4 THSD FT LOW CLOUD
SHIELD PUSHING NORTHEAST SHOULD ONLY BRIEFLY AFFECT MAINLY THE FAR
SOUTHEAST BEFORE HEADING OFF TO THE EAST. RUC AND NAM SATURATE THE
LOWER LEVELS LATER THIS MORNING ON THE RUC VERSUS THIS AFTERNOON
ON THE NAM. CURRENT TRENDS ON SATELLITE SUPPORT THE SLOWER NAM
WITH LOW CLOUDS FARTHER BEHIND THE COLD FRONT. NAM THEN DISSIPATES
THIS CLOUD LAYER WITH COLD AIR ADVECTION AND DRYING LATER TONIGHT.
HOWEVER MODELS TEND TO OVERDO THE DRYING SO WILL DELAY THE
CLEARING A LITTLE.
SHORT TERM...TUESDAY THROUGH WEDNESDAY NIGHT...FORECAST CONFIDENCE
MEDIUM.
NAM/CANADIAN AND GFS/ECMWF SHOWING DIFFERENT PATHS FOR THE SURFACE
LOW FOR TUESDAY INTO WEDNESDAY. THE NAM/CANADIAN SHOWS IT SHIFTING
FROM EAST CENTRAL OKLAHOMA TO SOUTHWEST MISSOURI TUESDAY...THEN TO
NORTH CENTRAL ILLINOIS TUESDAY NIGHT...THEN NORTHEAST INTO LAKE
HURON WEDNESDAY. THIS PATH BRINGS QPF INTO THE AREA TUESDAY
AFTERNOON AND EVENING...THEN ANOTHER SHOT ON WEDNESDAY.
GFS/ECMWF SHOWS THE LOW MOVING FROM EAST CENTRAL OKLAHOMA TO FAR
SOUTHERN MISSOURI TUESDAY...THEN TO NORTHERN INDIANA/NORTHWEST
OHIO TUESDAY NIGHT..BEFORE SHIFTING INTO THE NORTHEASTERN UNITED
STATES WEDNESDAY. THIS PATH BRINGS QPF INTO FAR SOUTHERN PORTIONS
OF THE AREA TUESDAY AFTERNOON...THEN TO THE SOUTHEAST HALF OF THE
AREA TUESDAY NIGHT. MOST QPF SHIFTS EAST ON WEDNESDAY.
ALL MODELS SHOWING WARM AIR ADVECTION TUESDAY AFTERNOON ACROSS THE
AREA...WITH IT CONTINUING TUESDAY NIGHT ON THE NAM/CANADIAN. THE
GFS/ECMWF KEEP THE WARM AIR ADVECTION MAINLY EAST OF THE AREA
TUESDAY NIGHT. MODELS ALSO BRING UPPER LOW TO EASTERN KANSAS
TUESDAY...THEN INTO NORTHERN ILLINOIS TUESDAY NIGHT...BEFORE
SHIFTING EAST WEDNESDAY.
AREA FORECAST SOUNDINGS ON THE NAM AND GFS INDICATED THAT ANY
PRECIPITATION ON TUESDAY WOULD BEGIN AS A LIGHT RAIN AND LIGHT
SNOW MIX...BEFORE THE ICE CRYSTAL INTRODUCTION IN THE SATURATED
PORTION OF THE AIR COLUMN DIMINISHES BY 00Z WEDNESDAY.
THEN...POTENTIAL FOR LIGHT FREEZING RAIN COMES INTO THE AREA AND
LASTS TUESDAY NIGHT...PERHAPS INTO EARLY WEDNESDAY. AREAS IN THE
FAR EAST MAY WARM ENOUGH TO BRING A MIX OF LIGHT FREEZING RAIN AND
LIGHT RAIN...OR ALL LIGHT RAIN. TUESDAY NIGHT INTO EARLY WEDNESDAY
MAY HAVE TO BE WATCHED FOR A FREEZING RAIN ADVISORY IF THESE
CONDITIONS LINGER IN THE MODELS IN SUBSEQUENT RUNS. SOME
UNCERTAINTY EXISTS...WITH BETTER SHOT BEING WITH THE STRONGER
SURFACE LOW IN THE NAM/CANADIAN MODELS THAN WEAKER LOW WITH THE
GFS/ECMWF.
NAM/CANADIAN SEEM TO SHOW AN ENHANCED AREA OF QPF ACROSS
SOUTHEASTERN SECTIONS OF THE AREA FOR THE 6 HOURS ENDING AT 18Z
WEDNESDAY. THIS SEEMS TO BE DRIVEN BY Q VECTOR CONVERGENCE.
GFS/ECMWF NOT SHOWING THIS...AND HAVE BEST LIFT EAST OF THE
REGION. AREA FORECAST SOUNDINGS SHOWING SUPPORT IN THE MORNING FOR
LIGHT FREEZING RAIN/LIGHT SNOW/LIGHT RAIN MIX IN THE WEST...WITH
MORE LIGHT RAIN IN THE FAR EAST WITH MILDER TEMPERATURES.
CONTINUED TO MENTION POPS IN THIS PERIOD...WITH SOME UNCERTAINTY
ON PRECIPITATION TYPES GIVEN THE MODEL DIFFERENCES. MILD
TEMPERATURES OVERALL CONTINUE FOR TUESDAY THROUGH WEDNESDAY.
QUIET WEATHER RETURNS FOR WEDNESDAY NIGHT...AHEAD OF ADVANCING
COLD FRONT. MILD TEMPERATURES ARE EXPECTED TO CONTINUE.
LONG TERM...THURSDAY THROUGH CHRISTMAS DAY...FORECAST CONFIDENCE
MEDIUM.
GFS/ECMWF BOTH SHOW A COLD FRONT SHIFTING SOUTHEAST THROUGH THE
REGION THURSDAY. ECMWF HINTING AT SOME LIGHT QPF WITH THIS
FEATURE...WITH THE GFS SHOWING LITTLE TO NONE. FOR NOW...LEANED
TOWARD THE CONSENSUS FORECAST AND LEFT LOW POPS FOR LIGHT SNOW
SHOWERS. MILD TEMPERATURES SHOULD LINGER.
MODELS THEN SHOW SIMILAR AND DIFFERENT TRENDS THURSDAY NIGHT
THROUGH CHRISTMAS DAY ACROSS THE REGION. THEY BOTH DO SHOW HIGH
PRESSURE PASSING TO THE NORTH OF THE REGION THURSDAY NIGHT AND
FRIDAY...WITH ITS RIDGE AXIS SHIFTING INTO THE AREA SATURDAY. THE
ECMWF TRIES TO KEEP AN INTACT SHORTWAVE TROUGH EXTENDING FROM THE
WESTERN GREAT LAKES TO THE CENTRAL AND SOUTHERN PLAINS STATES
FRIDAY. THE GFS KEEPS MORE OF A NORTHERN AND SOUTHERN STREAM
SEPARATELY...WITH AN UPPER LOW MOVING TOWARD THE AREA FRIDAY INTO
FRIDAY NIGHT.
THE GFS IS MUCH FURTHER SOUTH WITH THE BASE OF THE SHORTWAVE
TROUGH FRIDAY NIGHT. ANOTHER SHORTWAVE TROUGH THEN MOVES INTO THE
REGION FOR SATURDAY NIGHT INTO CHRISTMAS DAY. NOT MUCH QPF IN
MODELS WITH THIS FEATURE.
FOR NOW...WILL USE CONSENSUS APPROACH TO GRIDS GIVEN THE
DISAGREEMENT WITH FEATURES. THIS SHOULD KEEP THE FORECAST DRY FOR
NOW...WITH TEMPERATURES NEAR SEASONAL NORMALS.
AVIATION/12Z TAFS/...
THE WIND SHEAR POTENTIAL EARLY THIS MORNING ENDS AS THE 850MB JET
MAX OF 50 KNOTS PUSHES EAST INTO THE EASTERN GREAT LAKES.
THEN MAIN QUESTION IS STRATUS POTENTIAL. 4 THSD FT LOW CLOUDS MOVE
OFF WITH THE LOW LEVEL JET EARLY THIS MORNING. RUC AND NAM
SATURATE THE LOWER LEVELS LATER THIS MORNING ON THE RUC...WHICH
WOULD IMPLY IFR CIGS...VS THIS AFTERNOON ON THE NAM WHICH WOULD
MORE LIKELY BE MVFR CIGS. CURRENT TRENDS ON SATELLITE SUPPORT THE
SLOWER NAM WITH MVFR CIGS AFTER THE COLD FRONT. NAM SOUNDINGS THEN
DISSIPATES THE LOW LEVEL CLOUDS WITH COLD AIR ADVECTION AND DRYING
LATER TONIGHT. HOWEVER MODELS TEND TO OVERDO THE DRYING.
MARINE...
LOW PRESSURE NORTHEAST OF LAKE SUPERIOR WILL MOVE EAST. SMALL
CRAFT ADVISORY SOUTHWEST WINDS SHOULD DIMINISH THIS MORNING.
NORTH TO NORTHEAST WINDS MAY APPROACH SMALL CRAFT LEVELS THIS
AFTERNOON AND INTO THE EVENING BEHIND A TRAILING COLD FRONT. THIS
WILL HAVE TO BE WATCHED FOR ANOTHER POSSIBLE SMALL CRAFT ADVISORY.
&&
.MKX WATCHES/WARNINGS/ADVISORIES...
WI...NONE.
LM...NONE.
&&
$$
UPDATE...WIMBERLEY/DDV
TODAY/TONIGHT AND AVIATION/MARINE...HENTZ
TUESDAY THROUGH SUNDAY...WOOD
AREA FORECAST DISCUSSION
NWS CHEYENNE WY
910 AM MST MON DEC 19 2011
.UPDATE...DURING THE PAST HOUR...HAVE RECEIVED NUMEROUS REPORTS OF
VEHICLE ROLLOVERS IN PLATTE AND GOSHEN COUNTIES DUE TO BLACK ICE
FROM FREEZING DRIZZLE AND FOG. FOG HAS BEEN LOCALLY DENSE WITH
VISIBILITIES REDUCED TO A QUARTER MILE OR LESS FROM CHEYENNE NORTH
THROUGH WHEATLAND AND BORDEAUX. THE WINTER WEATHER ADVISORY WAS
ISSUED AT 851 AM AND REMAINS IN EFFECT UNTIL NOON FOR LARAMIE...
GOSHEN...PLATTE AND EASTERN ALBANY COUNTIES.
&&
.PREV DISCUSSION... /ISSUED 416 AM MST MON DEC 19 2011/
AVIATION...12Z TAFS
STRATUS CONTINUES TO MAKE ITS WAY SOUTH ACROSS THE NORTHERN
NEBRASKA PANHANDLE THIS MORNING. AM SEEING THE BACK EDGE THOUGH ON
STRATUS SATELLITE IMAGERY APPROACHING THE NORTHERN PANHANDLE...SO
KEPT CHADRON MVFR LATEST HRRR FORECAST LOOKS PRETTY GOOD ON TIMING
OF IFR/LIFR ONSET FOR AIRPORTS ALONG AND EAST OF THE LARAMIE RANGE
AND CONTINUE FOLLOWING ITS GUIDANCE. FOR KLAR AND KRWL...BELIEVE
THESE TWO AIRPORTS WILL COME DOWN IN LIGHT SNOW LATER THIS
MORNING. EVENTUALLY...BY MID AFTERNOON...AM EXPECTING STRATUS TO
BREAK UP AS WINDS SHIFT WESTERLY.
CLAYCOMB
PREV DISCUSSION... /ISSUED 250 AM MST MON DEC 19 2011/
SHORT TERM...TODAY THROUGH WEDNESDAY NIGHT.
TODAY...COLD FRONT QUICKLY PASSED SOUTHWARD ACROSS OUR COUNTIES
EARLIER TONIGHT WITH DECENT COLD AIR ADVECTION ONGOING WITH 2-4 MB 3
HOURLY PRESSURE RISES IN THE WAKE OF THE COLD FRONT. AS INPUT BY DAY
SHIFT FORECAST...WILL MAINTAIN PATCHY FREEZING DRIZZLE ACROSS OUR
PANHANDLE COUNTIES SOUTH OF SCOTTSBLUFF TO ALLIANCE AS THE
ATMOSPHERE SUGGEST FAVORABLE CONDITIONS. LOW AND MID LEVELS WILL
CONTINUE TO SATURATE THIS MORNING AND WITH FAVORABLE NORTHEAST TO
EAST UPSLOPE...AND DYNAMICS FROM PASSING SHORTWAVE TROUGH
ALOFT...WILL INCLUDE 60 TO 100 PERCENT POPS FOR SNOW THIS MORNING
ALONG AND JUST EAST OF THE LARAMIE RANGE WITH LESSER POPS FURTHER
EAST AND WEST DUE TO DRY AIR AT LOW LEVELS AND DOWNSLOPING EAST
WINDS WEST OF THE MOUNTAINS AND SNOW SHADOW EFFECTS. AREAS OF FOG
DEVELOP AS THE TEMPERATURE AND DEWPOINT SPREADS NARROW. SNOWFALL
ACCUMULATIONS LESS THAN 2 INCHES DUE TO PROGRESSIVE NATURE OF THE
SYSTEM AND LIMITED QPF. CHANCES FOR SNOW DECREASE SIGNIFICANTLY THIS
AFTERNOON...THOUGH REMAIN HIGH ACROSS THE SOUTHERN LARAMIE RANGE DUE
TO PERSISTENT EASTERLY UPSLOPE. MUCH COLDER THAN SUNDAY WITH CLOUDS
AND IN THE COLD AIRMASS BEHIND THE FRONT.
TONIGHT...DECREASING CLOUDS AND LIGHT WINDS WILL MAKE FOR A CHILLY
NIGHT WITH COLDEST CONDITIONS ACROSS THE LARAMIE VALLEY. WEAK LEE
TROUGHING DEVELOPS BUT SHOULD NOT HAVE MUCH EFFECT ON LOW
TEMPERATURES.
TUESDAY...SLOW WARMING TREND IN BETWEEN SYSTEMS. WITH SOME SUNSHINE
AND SURFACE LEE TROUGHING INDUCING DOWNSLOPE WARMING...WILL SEE HIGH
TEMPERATURES IN THE 20S WEST AND 30S EAST.
TUESDAY NIGHT...NOT AS COLD AS MONDAY NIGHT AS MID AND HIGH CLOUDS
INCREASE IN ADVANCE OF THE NEXT STRONGER SHORTWAVE TROUGH ALOFT
APPROACHING FROM IDAHO AND WESTERN MONTANA.
WEDNESDAY...RATHER IMPRESSIVE SHORTWAVE TROUGH ALOFT CONTINUES TO
DIG ACROSS IDAHO AND WESTERN WYOMING SENDING ANOTHER COLD FRONT
ACROSS OUR COUNTIES IN THE AFTERNOON. THE NAM SHOWS A DEEPLY
SATURATED LAYER DEVELOPING IN THE AFTERNOON ACROSS OUR COUNTIES IN
THE WAKE OF THE COLD FRONT WHILE THE GFS IS SLOWER IN THE
EVOLVEMENT. NAM TENDS TO DO BETTER IN THESE SITUATIONS AND THUS WILL
FOLLOW ITS SOLUTION BRINGING CHANCE OF SNOW ACROSS ALL OUR COUNTIES
IN THE AFTERNOON...WITH 50 TO 100 PERCENT POPS NORTH OF A RAWLINS TO
CHADRON LINE WITH DEEPLY SATURATED AIRMASS LIFTED BY DYNAMICS AND
OROGRAPHICS.
WEDNESDAY NIGHT...SHORTWAVE TROUGH ALOFT MOVES ACROSS WESTERN
COLORADO WITH DYNAMICS AND OROGRAPHICS PROVIDING THE LIFT OF OUR
SATURATED AIRMASS TO PRODUCE FAIRLY WIDESPREAD LIGHT SNOW OVER OUR
COUNTIES...WITH MOST COVERAGE OVER THE FAVORED UPSLOPE LOCATIONS
NEAR THE SOUTHERN LARAMIE RANGE OF WESTERN LARAMIE COUNTY.
LONG TERM...THURSDAY THROUGH MONDAY
19/00Z ECMWF AND GFS MODEL RUNS IN VERY GOOD AGREEMENT ON TRACK OF
LOW OVER UTAH THURSDAY MORNING POSITIONING OF PRECIPITATION OVER
WYOMING. GFS MORE BULLISH ON QPFS WITH EC MORE CONSERVATIVE. AM
BECOMING A LITTLE CONCERNED THOUGH WITH ACCUMULATING SNOWFALL AS
THIS TRACK IS A FAVORABLE PATTERN FOR US TO SEE SIGNIFICANT
SNOWFALL. LATER SHIFTS WILL NEED TO WATCH TO SEE IF THE LOW SLOWS
DOWN OR SHIFTS SLIGHTLY NORTH OF ITS CURRENT FORECAST TRACK.
LATEST TRACK ON BOTH THE GFS AND ECMWF HAS THE LOW TRACKING FROM
CENTRAL UTAH INTO SOUTHERN COLORADO AND FINALLY INTO NORTHERN NEW
MEXICO THURSDAY AFTERNOON. FOR NOW...HAVE SNOW ACCUMULATIONS OF 3
TO 5 INCHES FROM WEDNESDAY NIGHT THROUGH THURSDAY FOR MUCH OF THE
CWA WITH 10 TO 14 INCHES IN THE SNOWY AND SIERRA MADRE RANGES.
SNOW COMES TO AN END THURSDAY AFTERNOON WITH RIDGING MOVING INTO
THE AREA FROM THE NORTH. WESTERLY WINDS RETURN FRIDAY WITH 700MB
TEMPERATURES INCREASING FROM -14C THURSDAY AFTERNOON TO AROUND -6C
FRIDAY AFTERNOON. TEMPERATURES WILL BE TRICKY FRIDAY AND DEPENDS A
LOT ON RESIDING SNOW FROM THURSDAYS STORM. KEPT TEMPERATURES FAIRLY
COOL WITH LOW 30S FOR HIGHS EAST OF THE LARAMIE RANGE AND LOW 20S WEST.
LOOKS LIKE ANOTHER WEAK SHORTWAVE AND SURFACE COLD FRONT TO TRACK
THROUGH SOUTHEAST WYOMING SATURDAY. 700MB WINDS REALLY INCREASE
WITH THIS SYSTEM WITH GFS FORECASTING WINDS OF 50+ KT FRIDAY
AFTERNOON INTO SATURDAY MORNING. 700MB CRAIG TO CASPER HGT
GRADIENT AROUND 60 METERS AS WELL ON THE GFS DURING THAT TIME. DID
GO AHEAD AND INCREASE WIND SPEEDS FROM THURSDAY NIGHT THROUGH
FRIDAY NIGHT WITH THIS SYSTEM AND LATER SHIFTS WILL NEED TO WATCH
FOR WIND HIGHLIGHTS...ESPECIALLY FOR OUR WIND PRONE AREAS. WILL
ADD HIGH WIND POTENTIAL IN THIS MORNINGS HWO AS WELL.
PRETTY COLD WEEKEND AS 700MB TEMPERATURES FALL BACK DOWN TO -14 TO
-18C. LOOKING PROBABLY AT SINGLE DIGIT LOWS AND HIGHS STRUGGLING
TO GET ABOVE FREEZING. COULD BE COLDER DEPENDING ON ANY EXISTING
SNOW PACK FROM THURSDAYS STORM AS WELL.
FIRE WEATHER...
NO FIRE WEATHER CONCERNS. HIGHER MINIMUM AFTERNOON
RELATIVE HUMIDITIES TODAY IN THE WAKE OF THE COLD FRONT.
&&
.CYS WATCHES/WARNINGS/ADVISORIES...
WY...WINTER WEATHER ADVISORY UNTIL NOON MONDAY FOR WYZ106-WYZ107-
WYZ108-WYZ117-WYZ118-WYZ119.
NE...NONE.
&&
$$
SHORT TERM/FIRE WEATHER...RUBIN
LONG TERM/AVIATION...CLAYCOMB
UPDATE...JAMSKI