Forecast Discussions mentioning any of "HRRR" "RR" "RUC13" "RUC" received at GSD on 12/27/11


AREA FORECAST DISCUSSION
NWS COLUMBIA SC
905 AM EST SUN DEC 25 2011 .SYNOPSIS... HIGH PRESSURE WILL CONTINUE TO MOVE OFFSHORE THIS MORNING AS A WEAK AREA OF LOW PRESSURE DEVELOPS OVER THE WESTERN GULF STATES AND TRACKS EASTWARD. CLOUDS WILL THICKEN OVER THE AREA TODAY. SOME LIGHT RAIN MAY FALL OVER THE AREA LATER THIS AFTERNOON AND EVENING...PARTICULARLY OVER THE SOUTHERN HALF OF THE FORECAST AREA. HIGH PRESSURE TO THE NORTH WILL BUILD DOWN SUNDAY NIGHT AND MONDAY BRINGING DRIER AIR TO THE REGION. && .NEAR TERM /THROUGH TONIGHT/... HAVE TWEAKED THE POPS OVER THE REGION BASED UPON CURRENT RADAR TRENDS AND RUC FORECASTS. IN GENERAL POPS ARE INCREASED OVER THE SOUTHERN HALF OF THE CWA AND TEMPS WILL BE DECREASED SOME BASED UPON CLOUD COVER AND ANY EVAPORATIVE COOLING. MODELS SHOW SOME WEAK ISENTROPIC LIFT AS MAIN FORCING FOR CLOUDS AND PRECIP. PRECIPITATION AMOUNTS WILL BE LOW...GENERALLY AROUND ONE TENTH OF AN INCH OR LESS...MAYBE SLIGHTLY HIGHER ACROSS THE CSRA. BY TONIGHT...SYSTEM WILL MOVE EAST OF THE AREA AS S/W ENERGY SWINGS SE ACROSS THE GREAT LAKES/NEW ENGLAND AND MOISTURE MOVES OFF THE COAST. && .SHORT TERM /MONDAY THROUGH TUESDAY NIGHT/... MODELS HAVE CONTINUED TO COME INTO BETTER AGREEMENT WITH SYSTEM THAT WILL BE AFFECTING THE AREA MONDAY NIGHT INTO TUESDAY. HOWEVER...SOME SLIGHT TIMING DIFFERENCES STILL REMAIN AS MODELS HAVING A HARD TIME WITH CLOSED LOW EJECTING FROM WEST TX/SOUTHERN PLAINS REGION ON MONDAY INTO TUESDAY. AT THE SURFACE...A SYSTEM WILL DEVELOP IN THE GULF ON MONDAY AND STRENGTHEN AS IT TRACKS NORTHEAST...REMAINING WEST OF THE AREA...TUESDAY. ALL OF THE MODELS AND ENSEMBLES SHOW INCREASING CHANCES FOR RAIN BY MONDAY NIGHT INTO TUESDAY NIGHT. AS MENTIONED EARLIER...TIMING DIFFERENCES CONTINUE WITH MODELS. WILL BEGIN INCREASING POPS MONDAY NIGHT AND PEAK POPS OUT BY TUESDAY AFTERNOON AS THE ASSOCIATED COLD FRONT BEGINS TO APPROACH THE CWA. AIRMASS AHEAD OF THE SYSTEM BECOMES WEAKLY/MODERATELY UNSTABLE WITH A STRONG 50 TO 60 KT JET AROUND 5K FT. WILL BE CROSSING THE REGION. HAVE DECIDED TO MENTION THE POSSIBILITY OF A FEW ISOLATED THUNDERSTORMS TUESDAY AFTERNOON/EVENING IN ADVANCE OF THE COLD FRONT. SLOWLY IMPROVING CONDITIONS OVERNIGHT ON TUESDAY. TEMPERATURES WILL REMAIN SLIGHTLY ABOVE NORMAL THROUGH THE PERIOD. && .LONG TERM /WEDNESDAY THROUGH SATURDAY/... DURING THE EXTENDED PERIOD...THE FLOW ACROSS THE LOWER 48 WILL BECOME MORE ZONAL...ALTHOUGH A COUPLE OF WEAK UPPER TROUGHS APPROACH LATE IN THE PERIOD. IT LOOKS LIKE THE STORM TRACK REMAINS TO THE NORTH. HIGHS START IN THE MID TO UPPER 50S TUESDAY AND WEDNESDAY BUT ARE A BIT WARMER IN THE UPPER 50S TO LOWER 60S LATER IN THE PERIOD...MAINLY FRIDAY AND SATURDAY. LOW TEMPERATURES GENERALLY IN THE MID TO UPPER 30S. && .AVIATION /14Z SUNDAY THROUGH THURSDAY/... WEAK LOW PRESSURE DEVELOPING IN THE WESTERN GULF OF MEXICO WITH WEAKENING RIDGE ACROSS SOUTH CAROLINA/GEORGIA. RADAR AT 11Z SHOWING LIGHT RAIN ACROSS MISSISSIPPI AND ALABAMA SPREADING EAST. LATEST GUIDANCE INDICATING LOW TO MID LEVEL MOISTURE WILL ADVECT INTO THE REGION LATER THIS MORNING AND WITH MODEST ISENTROPIC LIFT THIS AFTERNOON EXPECT SOME AREAS OF LIGHT RAIN. LAMP AND MOS GUIDANCE POPS HAVE INCREASED AND CONFIDENCE NOW HIGH FOR MVFR CONDITIONS IN THE AGS/DNL AREAS WHERE MOISTURE DEEPEST/STRONGER LIFT AND CONVERGENCE LOCATED. LIGHT PRECIPITATION AT TIMES THIS AFTERNOON ACROSS ALL TERMINALS. AREA OF RAIN WILL MOVE EAST OF THE AREA AFTER 00Z WITH AIR MASS DRYING OUT. EXTENDED AVIATION OUTLOOK...CEILING/VISIBILITY RESTRICTIONS EXPECTED MONDAY NIGHT INTO TUESDAY AS LOW PRESSURE CROSSES THE REGION. && .CAE WATCHES/WARNINGS/ADVISORIES... SC...NONE. GA...NONE. && $$
AREA FORECAST DISCUSSION
NWS NORTHERN INDIANA
853 PM EST MON DEC 26 2011 .UPDATE... PREVIOUS FORECAST STILL LOOKS TO BE INLINE BASED ON CURRENT OBSERVATIONAL TRENDS AND HAVE MADE ONLY MINOR CHANGES IN REGARDS TO PRECIP TYPE/SNOW AMOUNTS. LARGE SWATH OF PRECIPITATION CONTINUES TO LIFT NORTHWARD FROM THE MID MS RIVER VALLEY WITH MORE NOTABLE NORTHWARD PUSH ACROSS CENTRAL ILLINOIS. CONSENSUS OF NUMERICAL MODEL OUTPUT HAS DONE A GOOD JOB LATCHING ONTO THIS AREA AND APPEARS TO BE TIED INTO ENHANCED LOW/MID LEVEL MOISTURE FLUX CONVERGENCE IN MID LEVEL CONFLUENCE ZONE SITUATED BETWEEN NORTHERN STREAM TROUGH AND CLOSED UPPER LOW ACROSS THE SOUTHERN PLAINS. 00Z RAOB DATA FROM NASHVILLE STILL INDICATED A DRY SUBCLOUD LAYER BELOW 10K FT AND REGIONAL RADAR DATA HAS INDICATED MORE A NORTHWARD STRUGGLE WITH PRECIPITATION TRYING TO MOVE INTO WESTERN KENTUCKY. IT STILL APPEARS IT WILL TAKE SOME TIME FOR FAR NORTHEAST AREAS IN TOP DOWN SATURATION PROCESS TO START RECEIVING PRECIPITATION AND CURRENT FORECAST ALREADY CAPTURES THIS IDEA...AND ONLY TWEAK TO 06Z-09Z POPS WAS TO INCREASE POPS ACROSS THE EXTREME WEST DUE TO ABOVE FACTORS. AFTER 09Z...MORE NOTABLE LOW LEVEL THETAE ADVECTION SURGE SHOULD ALLOW PRECIPITATION TO OVERSPREAD ENTIRE FORECAST AREA IN THE 09Z TO 12Z TIMEFRAME AS UPPER JET DYNAMICS BECOME MORE FAVORABLE ALSO. PRECIPITATION TYPE ISSUES STILL A PROBLEM GIVEN RATHER WARMISH BOUNDARY LAYER TEMPS BUT STILL COUNTING ON STRONG EVAPORATIVE COOLING PROCESSES TO ALLOW WET BULB PROCESSES TO RESULT IN MAINLY SN PRECIP TYPE AFTER 09Z OR 10Z. LOWER CONFIDENCE IN THIS SCENARIO TO ALL SNOW ACROSS THE SOUTHEAST HALF OF THE AREA HOWEVER DUE TO A WEAK LOW LEVEL MOIST TONGUE THAT COULD ALLOW FOR A SLIGHTLY LONGER THAN EXPECTED LIQUID OR MIXED PRECIP TYPE. GIVEN THE ABOVE...HAVE SLIGHTLY REDUCED OVERNIGHT ACCUMULATIONS GENERALLY ALONG AND EAST OF THE INTERSTATE 69 CORRIDOR WHERE THESE PRECIP TYPE CONCERNS ARE THE GREATEST...AND WHERE TOP DOWN SATURATION WILL BE MORE DELAYED TO AFTER 09Z. IMPACTS TO TWEAKS TO FORECAST IN TERMS OF STORM TOTAL SNOWFALL ARE MINIMAL HOWEVER...AS IT STILL APPEARS THE TUESDAY MORNING THROUGH EARLY TUESDAY AFTERNOON PERIOD SHOULD SET UP FOR A FAVORABLE QUICK SHOT OF WET SNOW WITH A PROGRESSIVE DEFORMATION BAND. INGREDIENTS METHOD CONSIDERATIONS STILL POINT TO EASTERN THIRD OF THE AREA AS EXPERIENCING THE BEST RESPONSE TO THIS FORCING WITH GENERAL AGREEMENT IN NAM/GFS CROSS SECTIONS OF ENHANCED UPPER LEVEL INSTABILITY COLOCATED WITH STRONGER SYNOPTIC FORCING. FORCING SHOULD BE SOMEWHAT ELEVATED HOWEVER AND PRELIMINARY LOOK AT CROSS SECTIONS SUGGESTS CORE OF STRONGEST VERTICAL MOTION MAY LIE JUST ABOVE FAVORABLE DENDRITIC GROWTH ZONE ACROSS THE EAST. TAKING THIS INTO CONSIDERATION ALONG WITH THERMAL PROFILES...HAVE STUCK WITH LOW SNOW TO LIQUID RATIOS ON THE ORDER OF 10 TO 1 WHICH COULD EVEN BE A BIT TOO HIGH. RECALCULATING STORM TOTAL SNOW GRIDS STILL COMES OUT TO 2 TO 4 INCHES ACROSS THE AREA WITH THE HIGHER AMOUNTS EXPECTED ACROSS EASTERN THIRD. NO CHANGES TO MINOR LAKE EFFECT ACCUMULATION ENHANCEMENT INTO TUESDAY AFTERNOON/EVENING. DESPITE 850 HPA TEMPS COOLING TO AROUND -10 DEG....INVERSION HEIGHTS REMAIN RELATIVELY WITH STRONG SYNOPTIC SCALE MID LEVEL DRYING AFTER 00Z THAT SHOULD LIMIT ADDITIONAL LAKE EFFECT ACCUMS. WILL LIKELY HOLD OFF ON HEADLINES AT THIS TIME WITH CURRENT FORECASTED SNOW TOTALS REMAINING BELOW ADVISORY LEVELS...AND LET NEXT SHIFT MONITOR UPSTREAM PRECIP TYPE TRENDS. UPDATED FORECAST TO BE SENT SHORTLY. && .PREV DISCUSSION... /ISSUED 632 PM EST MON DEC 26 2011/ AVIATION... LATEST 18Z MODEL GUIDANCE HOLD W/XPCNS FM PRIOR FCST. PCPN RAPIDLY EXPANDING NEWD OUT OF ERN MO/NRN AR THIS EVENING AS SRN STREAM SW OVR NE TX BEGINS PHASING W/NRN STREAM TROUGH OVR NRN MN. NWD RTNG GOMEX MSTR SURGE QUITE EVIDENT PER UPSTREAM RADAR TRENDS AND PER RECENT UPSWING IN LIGHTNING ARISING WITHIN VIGOROUS CONVN ACRS WRN MS. TOP DOWN SATURATION WILL OCCUR RAPIDLY BTWN 06-09Z W/COMMENSURATE RAPID DETERIORATION TO IFR CONDS XPCD AND WHICH SHLD LAST BTR PART OF TUESDAY. BRIEF RAIN SNOW MIX STILL ANTICIPATED BUT PRIMARILY A SNOW EVENT W/BURST OF MOD SNOW ON TARGET IN 09Z WEST TO 18Z EAST TIME WINDOW. HRRR AND OTHER HIGHRES GUIDANCE SUGGESTS UP TO 1/2 IN/HR SNOW RATES FOR A TIME TUE MORNING AND MAY NEED TO REACCESS FCST VSBYS IN LTR ISSUANCES. HWVR GIST OF PRIOR FCST STILL HOLDS. SHORT TERM... POTENT SRN STREAM CIRC OVR N TX THIS AFTN WILL EJECT RAPIDLY E NR TERM AHD OF STG NRN STREAM SW ALONG THE US/CANADIAN BORDER BFR LIFTING UP ALG THE WRN APPALACHIANS ON TUE. NEWD TRANSLATION OF UPR JET STREAK AND RAPID NWD LL MSTR SURGE WILL YIELD A RAPID NEWD ARCHED ZONE OF PCPN TWD MIDNIGHT ACRS NW ZONES AND PRIOR W-E ORIENTED TEMPORAL POP SPLIT LOOKS IDEAL. MOST SIG SHRT TERM CHALLENGE IS TIMING OF CHG OVR LT TONIGHT YET WHICH AFFECTS END RESULT SNOW ACCUMS MOST. OF CONCERN LIES W/QUICKER ONSET OF SNOW SEEN IN HIGHRES GUIDANCE AND OF WHICH IS ALSO CONSIDERABLY WETTER. HWVR 12Z CONSENSUS TRENDS ARE SLOWER PHASING SYS/S ALOFT WHICH SUGGESTS SLOWER TOP DOWN COOLING AND THUS SLOWER CHG OVER. REGARDLESS RAIN CHANGING TO SNOW WINDOW WILL BE BRIEF...ON THE ORDER OF 2-3 HOURS SLANTED W-E BUT ALSO TIMED W/MORE INTENSE PCPN RATES. STRATEGY FOR THIS AFTN WAS BASED ON A BLENDED MODEL MIX WEIGHTED SOMEWHAT TWD 12Z HIGHRES NOD AS FOR QPF. NET RESULT CHANGED LTL FM 00Z GRIDS W/SIMILAR SNOW TOTALS AS MORE MEANINGFUL INFORMATION WILL BE GLEANED THROUGH THIS EVENING AS UPSTREAM PCPN SHIELD DVLPS AND ADVTS NEWD. 18Z GUIDANCE MAY OFFER COMPELLING ARGUMENTS TO DICTATE A GREATER SNOW GRID AS WELL ESP IN CONTEXT OF CAA BURST BEHIND INVERTED SFC TROUGH TUE AND A PD OF FOCUSED LK ENHANCEMENT LOOKS LIKELY ACRS NWRN ZONES W/ADDNL LIGHT ACCUMULATION LIKELY. OTHERWISE CONTD RAPID EJECTION OF PHASING SYS/S ALOFT XPCD THROUGH TUE NIGHT UP ACRS NEW ENGLAND. THIS WILL KEEP SC LOCKED IN BENEATH POST FNTL INVERSION AND WILL STRAY SIGLY WARMER THAN MOS W/TUE NIGHT MINS. LONG TERM... WEDNESDAY THROUGH MONDAY A TRANSITION TO PERTURBED FAST WNW FLOW WILL OFFER POOR MODEL PERFORMANCE IN THE LONG TERM PERIOD...RESULTING IN LOW CONFIDENCE FORECAST PREDICTIONS. ESP GIVEN A DEVELOPING LARGE DISCONTINUITY AMONG DETERMINISTIC SOLUTIONS PER EARLY NEXT WEEK. CONSENSUS BLEND CONTINUED TO LATCH ONTO TWO MORE PROMINENT...BUT LIKELY POORLY TIMED DISTURBANCES THUR-FRI AND SUN-MON...THUS CONTINUED WX MENTION OVER A BROAD PERIOD WITH A RAIN/SNOW MENTION OVER MOST OF THE AREA GIVEN WARM THERMAL FIELDS. PERTURBED FLOW WILL SUPPORT INCREASED CHANCES FOR PRECIP...BUT SYSTEM TRACK/TIMING/AND STRENGTH ARE FAR FROM A CERTAINTY. THUS...CONTINUED TO SIDE HEAVY TO CONTINUITY...RETAINING PREVIOUS PERIOD WX MENTIONS. THE 12Z ECMWF CONTINUES TO SUPPORT A FAIRLY SIG TROUGH INTO THE MID CONUS BY EARLY NEXT WEEK GIVEN PROGGED LONGWAVE H5 PHASING OVER THE CANADIAN PRAIRIE PROVINCES...WHICH COULD SUPPORT A CP OR MODIFIED ARCTIC AIRMASS INTO THE GREAT LAKES NEXT WEEK. HOWEVER...GIVEN LACK OF SIG DOWNSTREAM GREENLAND BLOCKING...NOT OVERLY CONVINCED ON THE INTENSITY AND DURATION SIG CAA INTO THE REGION ATTM. OVERALL...TEMPS WILL REMAIN ABOVE NORMAL IN THE PERIOD...WITH THE POTENTIAL LOOMING FOR A SIG WARM UP TOWARD LATE THIS WEEKEND IF A SIG DEEP LONGWAVE UPPER TROUGH /AS PROGGED IN THE ECMWF/ DEVELOPS. THIS TROUGH WOULD LIKELY END UP BIASED SLOWER GIVEN BACKSIDE UPPER JET INDUCED DIGGING...SUPPORTING A DELAY IN CAA UNTIL POSSIBLY MONDAY. && .IWX WATCHES/WARNINGS/ADVISORIES... IN...NONE. MI...NONE. OH...NONE. LM...GALE WATCH FROM TUESDAY AFTERNOON THROUGH LATE TUESDAY NIGHT FOR LMZ043-046. SMALL CRAFT ADVISORY UNTIL 3 PM EST TUESDAY FOR LMZ043-046. && $$ SHORT TERM...T LONG TERM...JC AVIATION...T UPDATE...MARSILI
AREA FORECAST DISCUSSION
NWS NORTHERN INDIANA
632 PM EST MON DEC 26 2011 .AVIATION... LATEST 18Z MODEL GUIDANCE HOLD W/XPCNS FM PRIOR FCST. PCPN RAPIDLY EXPANDING NEWD OUT OF ERN MO/NRN AR THIS EVENING AS SRN STREAM SW OVR NE TX BEGINS PHASING W/NRN STREAM TROUGH OVR NRN MN. NWD RTNG GOMEX MSTR SURGE QUITE EVIDENT PER UPSTREAM RADAR TRENDS AND PER RECENT UPSWING IN LIGHTNING ARISING WITHIN VIGOROUS CONVN ACRS WRN MS. TOP DOWN SATURATION WILL OCCUR RAPIDLY BTWN 06-09Z W/COMMENSURATE RAPID DETERIORATION TO IFR CONDS XPCD AND WHICH SHLD LAST BTR PART OF TUESDAY. BRIEF RAIN SNOW MIX STILL ANTICIPATED BUT PRIMARILY A SNOW EVENT W/BURST OF MOD SNOW ON TARGET IN 09Z WEST TO 18Z EAST TIME WINDOW. HRRR AND OTHER HIGHRES GUIDANCE SUGGESTS UP TO 1/2 IN/HR SNOW RATES FOR A TIME TUE MORNING AND MAY NEED TO REACCESS FCST VSBYS IN LTR ISSUANCES. HWVR GIST OF PRIOR FCST STILL HOLDS. && .SHORT TERM... POTENT SRN STREAM CIRC OVR N TX THIS AFTN WILL EJECT RAPIDLY E NR TERM AHD OF STG NRN STREAM SW ALONG THE US/CANADIAN BORDER BFR LIFTING UP ALG THE WRN APPALACHIANS ON TUE. NEWD TRANSLATION OF UPR JET STREAK AND RAPID NWD LL MSTR SURGE WILL YIELD A RAPID NEWD ARCHED ZONE OF PCPN TWD MIDNIGHT ACRS NW ZONES AND PRIOR W-E ORIENTED TEMPORAL POP SPLIT LOOKS IDEAL. MOST SIG SHRT TERM CHALLENGE IS TIMING OF CHG OVR LT TONIGHT YET WHICH AFFECTS END RESULT SNOW ACCUMS MOST. OF CONCERN LIES W/QUICKER ONSET OF SNOW SEEN IN HIGHRES GUIDANCE AND OF WHICH IS ALSO CONSIDERABLY WETTER. HWVR 12Z CONSENSUS TRENDS ARE SLOWER PHASING SYS/S ALOFT WHICH SUGGESTS SLOWER TOP DOWN COOLING AND THUS SLOWER CHG OVER. REGARDLESS RAIN CHANGING TO SNOW WINDOW WILL BE BRIEF...ON THE ORDER OF 2-3 HOURS SLANTED W-E BUT ALSO TIMED W/MORE INTENSE PCPN RATES. STRATEGY FOR THIS AFTN WAS BASED ON A BLENDED MODEL MIX WEIGHTED SOMEWHAT TWD 12Z HIGHRES NOD AS FOR QPF. NET RESULT CHANGED LTL FM 00Z GRIDS W/SIMILAR SNOW TOTALS AS MORE MEANINGFUL INFORMATION WILL BE GLEANED THROUGH THIS EVENING AS UPSTREAM PCPN SHIELD DVLPS AND ADVTS NEWD. 18Z GUIDANCE MAY OFFER COMPELLING ARGUMENTS TO DICTATE A GREATER SNOW GRID AS WELL ESP IN CONTEXT OF CAA BURST BEHIND INVERTED SFC TROUGH TUE AND A PD OF FOCUSED LK ENHANCEMENT LOOKS LIKELY ACRS NWRN ZONES W/ADDNL LIGHT ACCUMULATION LIKELY. OTHERWISE CONTD RAPID EJECTION OF PHASING SYS/S ALOFT XPCD THROUGH TUE NIGHT UP ACRS NEW ENGLAND. THIS WILL KEEP SC LOCKED IN BENEATH POST FNTL INVERSION AND WILL STRAY SIGLY WARMER THAN MOS W/TUE NIGHT MINS. && .LONG TERM... WEDNESDAY THROUGH MONDAY A TRANSITION TO PERTURBED FAST WNW FLOW WILL OFFER POOR MODEL PERFORMANCE IN THE LONG TERM PERIOD...RESULTING IN LOW CONFIDENCE FORECAST PREDICTIONS. ESP GIVEN A DEVELOPING LARGE DISCONTINUITY AMONG DETERMINISTIC SOLUTIONS PER EARLY NEXT WEEK. CONSENSUS BLEND CONTINUED TO LATCH ONTO TWO MORE PROMINENT...BUT LIKELY POORLY TIMED DISTURBANCES THUR-FRI AND SUN-MON...THUS CONTINUED WX MENTION OVER A BROAD PERIOD WITH A RAIN/SNOW MENTION OVER MOST OF THE AREA GIVEN WARM THERMAL FIELDS. PERTURBED FLOW WILL SUPPORT INCREASED CHANCES FOR PRECIP...BUT SYSTEM TRACK/TIMING/AND STRENGTH ARE FAR FROM A CERTAINTY. THUS...CONTINUED TO SIDE HEAVY TO CONTINUITY...RETAINING PREVIOUS PERIOD WX MENTIONS. THE 12Z ECMWF CONTINUES TO SUPPORT A FAIRLY SIG TROUGH INTO THE MID CONUS BY EARLY NEXT WEEK GIVEN PROGGED LONGWAVE H5 PHASING OVER THE CANADIAN PRAIRIE PROVINCES...WHICH COULD SUPPORT A CP OR MODIFIED ARCTIC AIRMASS INTO THE GREAT LAKES NEXT WEEK. HOWEVER...GIVEN LACK OF SIG DOWNSTREAM GREENLAND BLOCKING...NOT OVERLY CONVINCED ON THE INTENSITY AND DURATION SIG CAA INTO THE REGION ATTM. OVERALL...TEMPS WILL REMAIN ABOVE NORMAL IN THE PERIOD...WITH THE POTENTIAL LOOMING FOR A SIG WARM UP TOWARD LATE THIS WEEKEND IF A SIG DEEP LONGWAVE UPPER TROUGH /AS PROGGED IN THE ECMWF/ DEVELOPS. THIS TROUGH WOULD LIKELY END UP BIASED SLOWER GIVEN BACKSIDE UPPER JET INDUCED DIGGING...SUPPORTING A DELAY IN CAA UNTIL POSSIBLY MONDAY. && .IWX WATCHES/WARNINGS/ADVISORIES... IN...NONE. MI...NONE. OH...NONE. LM...SMALL CRAFT ADVISORY FROM 7 PM THIS EVENING TO 6 AM EST WEDNESDAY FOR LMZ043. SMALL CRAFT ADVISORY FROM 3 PM TUESDAY TO 6 AM EST WEDNESDAY FOR LMZ046. && $$ SHORT TERM...T LONG TERM...JC AVIATION...T
AREA FORECAST DISCUSSION
NWS GOODLAND KS
1221 PM MST SUN DEC 25 2011 .SYNOPSIS... IR SATELLITE IMAGERY SHOWED CLEAR SKIES OVER THE CENTRAL PLAINS. LATEST RUC UPPER AIR ANALYSIS SHOWED THE WESTERN HALF OF THE CONUS UNDER AN UPPER LEVEL RIDGE...AND A CLOSED LOW REMAINING NEARLY STATIONARY OVER WESTERN TEXAS AND EASTERN NEW MEXICO. AT THE SURFACE...HIGH PRESSURE WAS MAKING ITS WAY INTO THE TRI-STATE AREA. JTL && .SHORT TERM (TODAY-TUESDAY)... 223 AM MST SUN DEC 25 2011 MAIN ISSUE WITH THE FORECAST WILL BE TEMPERATURES. FOR MOST OF THE AREA TEMPERATURES WILL CONTINUE TO BE NEAR OR ABOVE NORMAL THROUGH THE PERIOD. OVER THE AREAS THAT HAVE EXCESSIVE SNOW COVER TEMPERATURES WILL BE 5 TO 10 DEGREES COOLER. UPPER LEVEL AND SURFACE HIGH PRESSURE WILL REMAIN OVER THE TRI-STATE AREA TODAY THROUGH EARLY MONDAY WITH THE UPPER LEVEL CLOSED LOW WOBBLING OVER THE TEXAS PANHANDLE. WINDS WILL BE LIGHT AS A SURFACE HIGH PRESSURE MOVES ACROSS THE AREA TODAY. MONDAY A SHORT WAVE TROUGH MOVES THROUGH THE UPPER LEVEL FLOW PUSHING THE CLOSED LOW EAST. AT THE SURFACE A PRE-FRONTAL TROUGH WILL ACCOMPANY THE UPPER LEVEL FEATURE. WITH A STRONGER PRESSURE GRADIENT IN PLACE AS THE TROUGH MOVES THROUGH...WINDS WILL STRENGTHEN AHEAD AND ESPECIALLY BEHIND THE TROUGH. WINDS WILL BECOME GUSTY AS STRONGER WINDS ABOVE THE SURFACE ARE ABLE TO MIX DOWN TO THE GROUND. COOLER AIR WILL MOVE IN BEHIND THE TROUGH. WINDS WILL WEAKEN OVERNIGHT AS HIGH PRESSURE BUILDS IN BEHIND THE TROUGH. TUESDAY A SHORT WAVE TROUGH WILL MOVE THROUGH THE UPPER LEVEL FLOW OVER THE AREA DURING THE EVENING. UPPER LEVEL MOISTURE INCREASES AND THERE IS SOME LIFTING ASSOCIATED WITH THE TROUGH PASSAGE. HOWEVER A DRY LAYER REMAINS BETWEEN THE MOISTURE AND THE SURFACE WHICH WILL LIKELY EVAPORATE ANY PRECIPITATION THAT MAY FORM. JTL .LONG TERM (WEDNESDAY-SATURDAY)... 223 AM MST SUN DEC 25 2011 A WEAK UPPER LEVEL DISTURBANCE MOVES OUT OF THE NORTHERN ROCKIES ON THURSDAY. BEST LIFT AND MOISTURE WILL BE FAR TO THE NORTH OF THE LOCAL AREA. OTHERWISE...A DRY WESTERLY FLOW WILL DOMINATE WITH NO PRECIPITATION CHANCES AND TEMPERATURES ABOVE NORMAL. /024 && .AVIATION... 1215 PM MST SUN DEC 25 2011 KMCK AND KGLD WILL HAVE VFR CONDITONS WITH LIGHT NORTHWEST WINDS THROUGH THE REMAINDER OF SUNDAY...SUNDAY NIGHT AND MONDAY. WINDS WILL TURN SOUTHWEST OVERNIGHT AND THEN BECOME WEST ON SUNDAY. LOCKHART && .GLD WATCHES/WARNINGS/ADVISORIES... KS...NONE. NE...NONE. CO...NONE. && $$
AREA FORECAST DISCUSSION
NWS GOODLAND KS
420 AM MST SUN DEC 25 2011 .SYNOPSIS... IR SATELLITE IMAGERY SHOWED CLEAR SKIES OVER THE CENTRAL PLAINS. LATEST RUC UPPER AIR ANALYSIS SHOWED THE WESTERN HALF OF THE CONUS UNDER AN UPPER LEVEL RIDGE...AND A CLOSED LOW REMAINING NEARLY STATIONARY OVER WESTERN TEXAS AND EASTERN NEW MEXICO. AT THE SURFACE...HIGH PRESSURE WAS MAKING ITS WAY INTO THE TRI-STATE AREA. JTL && .SHORT TERM (TODAY-TUESDAY)... 223 AM MST SUN DEC 25 2011 MAIN ISSUE WITH THE FORECAST WILL BE TEMPERATURES. FOR MOST OF THE AREA TEMPERATURES WILL CONTINUE TO BE NEAR OR ABOVE NORMAL THROUGH THE PERIOD. OVER THE AREAS THAT HAVE EXCESSIVE SNOW COVER TEMPERATURES WILL BE 5 TO 10 DEGREES COOLER. UPPER LEVEL AND SURFACE HIGH PRESSURE WILL REMAIN OVER THE TRI-STATE AREA TODAY THROUGH EARLY MONDAY WITH THE UPPER LEVEL CLOSED LOW WOBBLING OVER THE TEXAS PANHANDLE. WINDS WILL BE LIGHT AS A SURFACE HIGH PRESSURE MOVES ACROSS THE AREA TODAY. MONDAY A SHORT WAVE TROUGH MOVES THROUGH THE UPPER LEVEL FLOW PUSHING THE CLOSED LOW EAST. AT THE SURFACE A PRE-FRONTAL TROUGH WILL ACCOMPANY THE UPPER LEVEL FEATURE. WITH A STRONGER PRESSURE GRADIENT IN PLACE AS THE TROUGH MOVES THROUGH...WINDS WILL STRENGTHEN AHEAD AND ESPECIALLY BEHIND THE TROUGH. WINDS WILL BECOME GUSTY AS STRONGER WINDS ABOVE THE SURFACE ARE ABLE TO MIX DOWN TO THE GROUND. COOLER AIR WILL MOVE IN BEHIND THE TROUGH. WINDS WILL WEAKEN OVERNIGHT AS HIGH PRESSURE BUILDS IN BEHIND THE TROUGH. TUESDAY A SHORT WAVE TROUGH WILL MOVE THROUGH THE UPPER LEVEL FLOW OVER THE AREA DURING THE EVENING. UPPER LEVEL MOISTURE INCREASES AND THERE IS SOME LIFTING ASSOCIATED WITH THE TROUGH PASSAGE. HOWEVER A DRY LAYER REMAINS BETWEEN THE MOISTURE AND THE SURFACE WHICH WILL LIKELY EVAPORATE ANY PRECIPITATION THAT MAY FORM. JTL .LONG TERM (WEDNESDAY-SATURDAY)... 223 AM MST SUN DEC 25 2011 A WEAK UPPER LEVEL DISTURBANCE MOVES OUT OF THE NORTHERN ROCKIES ON THURSDAY. BEST LIFT AND MOISTURE WILL BE FAR TO THE NORTH OF THE LOCAL AREA. OTHERWISE...A DRY WESTERLY FLOW WILL DOMINATE WITH NO PRECIPITATION CHANCES AND TEMPERATURES ABOVE NORMAL. /024 && .AVIATION... 420 AM MST SUN DEC 25 2011 VFR CONDITIONS EXPECTED THE NEXT 24 HOURS. HIGH PRESSURE WILL DOMINATE THE WEATHER PATTERN AND SLIDE FROM THE ROCKIES INTO THE CENTRAL PLAINS. THIS WILL CAUSE WINDS TO SHIFT FROM THE NORTHWEST TO SOUTHWEST BY THE END OF THE PERIOD. BAS/024 && .GLD WATCHES/WARNINGS/ADVISORIES... KS...NONE. NE...NONE. CO...NONE. && $$
AREA FORECAST DISCUSSION
NWS GOODLAND KS
232 AM MST SUN DEC 25 2011 .SYNOPSIS... IR SATELLITE IMAGERY SHOWED CLEAR SKIES OVER THE CENTRAL PLAINS. LATEST RUC UPPER AIR ANALYSIS SHOWED THE WESTERN HALF OF THE CONUS UNDER AN UPPER LEVEL RIDGE...AND A CLOSED LOW REMAINING NEARLY STATIONARY OVER WESTERN TEXAS AND EASTERN NEW MEXICO. AT THE SURFACE...HIGH PRESSURE WAS MAKING ITS WAY INTO THE TRI-STATE AREA. JTL && .SHORT TERM (TODAY-TUESDAY)... 223 AM MST SUN DEC 25 2011 MAIN ISSUE WITH THE FORECAST WILL BE TEMPERATURES. FOR MOST OF THE AREA TEMPERATURES WILL CONTINUE TO BE NEAR OR ABOVE NORMAL THROUGH THE PERIOD. OVER THE AREAS THAT HAVE EXCESSIVE SNOW COVER TEMPERATURES WILL BE 5 TO 10 DEGREES COOLER. UPPER LEVEL AND SURFACE HIGH PRESSURE WILL REMAIN OVER THE TRI-STATE AREA TODAY THROUGH EARLY MONDAY WITH THE UPPER LEVEL CLOSED LOW WOBBLING OVER THE TEXAS PANHANDLE. WINDS WILL BE LIGHT AS A SURFACE HIGH PRESSURE MOVES ACROSS THE AREA TODAY. MONDAY A SHORT WAVE TROUGH MOVES THROUGH THE UPPER LEVEL FLOW PUSHING THE CLOSED LOW EAST. AT THE SURFACE A PRE-FRONTAL TROUGH WILL ACCOMPANY THE UPPER LEVEL FEATURE. WITH A STRONGER PRESSURE GRADIENT IN PLACE AS THE TROUGH MOVES THROUGH...WINDS WILL STRENGTHEN AHEAD AND ESPECIALLY BEHIND THE TROUGH. WINDS WILL BECOME GUSTY AS STRONGER WINDS ABOVE THE SURFACE ARE ABLE TO MIX DOWN TO THE GROUND. COOLER AIR WILL MOVE IN BEHIND THE TROUGH. WINDS WILL WEAKEN OVERNIGHT AS HIGH PRESSURE BUILDS IN BEHIND THE TROUGH. TUESDAY A SHORT WAVE TROUGH WILL MOVE THROUGH THE UPPER LEVEL FLOW OVER THE AREA DURING THE EVENING. UPPER LEVEL MOISTURE INCREASES AND THERE IS SOME LIFTING ASSOCIATED WITH THE TROUGH PASSAGE. HOWEVER A DRY LAYER REMAINS BETWEEN THE MOISTURE AND THE SURFACE WHICH WILL LIKELY EVAPORATE ANY PRECIPITATION THAT MAY FORM. JTL .LONG TERM (WEDNESDAY-SATURDAY)... 223 AM MST SUN DEC 25 2011 A WEAK UPPER LEVEL DISTURBANCE MOVES OUT OF THE NORTHERN ROCKIES ON THURSDAY. BEST LIFT AND MOISTURE WILL BE FAR TO THE NORTH OF THE LOCAL AREA. OTHERWISE...A DRY WESTERLY FLOW WILL DOMINATE WITH NO PRECIPITATION CHANCES AND TEMPERATURES ABOVE NORMAL. /024 && .AVIATION... 935 PM MST SAT DEC 24 2011 VFR CONDITIONS EXPECTED THE NEXT 24 HOURS. HIGH PRESSURE WILL DOMINATE THE WEATHER PATTERN AND SLIDE FROM THE ROCKIES INTO THE CENTRAL PLAINS. THIS WILL CAUSE WINDS TO SHIFT FROM THE NORTHWEST TO SOUTHWEST BY THE END OF THE PERIOD. BAS && .GLD WATCHES/WARNINGS/ADVISORIES... KS...NONE. NE...NONE. CO...NONE. && $$
AREA FORECAST DISCUSSION
NWS GRAY ME
1202 AM EST SUN DEC 25 2011 .SYNOPSIS... HIGH PRESSURE WILL CREST OVER THE REGION TONIGHT AND SHIFT OFFSHORE. A WEAK WARM FRONT WILL APPROACH FROM THE SOUTHWEST ON SUNDAY AHEAD OF LOW PRESSURE MOVING OUT OF THE GREAT LAKES. LOW PRESSURE WILL CROSS THE AREA SUNDAY NIGHT DRAGGING A COLD FRONT THROUGH THE AREA. HIGH PRESSURE WILL BUILD INTO THE AREA ON MONDAY AND WILL SHIFT OFFSHORE MONDAY NIGHT. A COLD FRONT WILL MOVE TOWARD THE REGION FROM THE NORTHWEST ON TUESDAY AND WILL STALL OVER NEW ENGLAND TUESDAY NIGHT AS LOW PRESSURE MOVES UP THE EAST COAST. LOW PRESSURE WILL TRACK SOUTH OF NEW ENGLAND AND INTO THE MARITIMES ON WEDNESDAY. HIGH PRESSURE WILL BUILD OVER THE AREA WEDNESDAY NIGHT AND THURSDAY. && .NEAR TERM /UNTIL 6 AM SUNDAY MORNING/... 1159 PM...MINOR ADJUSTMENTS TO CLOUD COVER FOR OCEAN EFFECT CLOUDS AND SNOW SHOWERS PRESENTLY ACROSS SOUTHEAST NEW HAMPSHIRE AND PARTS OF SOUTHERN YORK COUNTY. OTHERWISE...MINOR ADJUSTMENTS TO 1ST PERIOD GRIDS. I ADJUSTED WINDS UP ON THE WATERS OVERNIGHT IN NE FLOW. PREV DISC... UPDATE...OCEAN EFFECT CLOUDS ARE DEVELOPING OFF THE SEACOAST ATTM...WITH CLOUD TOPS COOLING QUICKLY OVER THE LAST HR. WEAK ECHOES ALSO BECOMING EVIDENT ON BOTH THE KGYX AND KBOX 88D. HAVE MOVED POP SLIGHTLY TO ACCOUNT FOR THESE TRENDS...BUT FCST REMAINS ON TRACK FOR TNGT. PREVIOUS DISCUSSION...ALSO WATCHING THE POTENTIAL FOR OCEAN EFFECT SHSN TO DEVELOP FOR THE SEACOAST AROUND MIDNIGHT. SSTS AROUND +8C WITH H85 TEMPS RUNNING AROUND -13C ARE PROVIDING FOR SOME PRETTY GOOD DELTA T VALUES. AS WINDS VEER LATE THIS EVE...ONSHORE FLOW WILL DEVELOP FOR THE SEACOAST...AND WOULD NOT BE SURPRISED TO SEE SHSN MOVE ONSHORE AS WELL. 12Z GFS HAD LATCHED ONTO THIS IDEA...AND WHILE THE NAM HAD NO QPF FOR THE AREA WEAK OMEGA WAS INDICATED AT THE BOTTOM OF THE SATURATED SNOW GROWTH ZONE IN BUFKIT PROFILES. HRRR SUPPORTS A FEW HRS OF SHSN AS WELL...WITH A DUSTING TO A HALF INCH ACCUM PSBL. HAVE UPPED POP TO CHC CENTERED ON THE BEST PARAMETERS AND TRENDED EITHER SIDE FROM THERE. FLOW BECOME DISORGANIZED VERY EARLY SUN...BEFORE ONSHORE FLOW BECOMES ENHANCED ALONG MIDCOAST. STRONG SURFACE HIGH PRESSURE WILL CREST OVER THE REGION TONIGHT...THEN MOVE OFFSHORE LATE. INITIAL CLEAR CALM CONDITIONS WITH SNOW COVER IN MOST AREAS WILL ALLOW TEMPERATURES TO FALL VERY QUICKLY. INCREASING CIRRUS LATER ON WILL PROBABLY SLOW DOWN THE TEMP DROPS...BUT PROBABLY NOT BEFORE GUIDANCE MINS ARE MET. EXPECT THE GOOD RADIATORS TO DROP TO AROUND ZERO...AND THE BEST RADIATORS DROP BELOW. && .SHORT TERM /6 AM SUNDAY MORNING THROUGH 6 PM SUNDAY/... A WAA REGIME WILL GET GOING SUNDAY MORNING AS HIGH PRESSURE MOVES OFFSHORE AND A SHORT WAVE TROUGH APPROACHES FROM THE WEST. MAY ACTUALLY SEE SOME LIGHT OCEAN EFFECT SNOWS ON THE MID COAST BY LATE MORNING. DURING THE AFTERNOON...LARGE SCALE FORCING FOR ASCENT WILL COMMENCE AS THE COLUMN MOISTENS UP. THIS SHOULD ALLOW FOR SOME LIGHT SNOW TO DEVELOP ACROSS A GOOD PORTION OF THE AREA. ACCUMS WON/T BE MUCH...PROBABLY A DUSTING TO AN INCH DURING THE DAY...PERHAPS A TOUCH MORE IN LINCOLN...KNOX...AND WALDO COUNTIES IN MAINE DUE TO OCEAN ENHANCEMENT. I SUPPOSE THE NH COAST AND THE REST OF THE MAINE COAST COULD SEE SOME OF THIS TOO WHILE THE WINDS ARE E/SE...BUT LESS CONFIDENCE THERE. SOMETHING TO WATCH LATE TONIGHT AND EARLY TOMORROW MORNING THOUGH. THE STRONG SHORT WAVE TROUGH WILL BE KNOCKING ON OUR DOOR SUNDAY EVENING...AND WILL MOVE OVERHEAD OVERNIGHT. STABILITY DECREASES AS THIS HAPPENS...AS TOTAL TOTAL INDICES RISE WELL INTO THE 50S. AS THIS HAPPENS...WE EXPECT AT LEAST SCATTERED SNOW SQUALLS TO DEVELOP...ESPECIALLY AS WE MOVE TOWARD LATE EVENING AND MIDNIGHT. THESE SQUALLS COULD PUT DOWN A QUICK INCH OR TWO AND CAUSE LOCALLY HAZARDOUS DRIVING CONDITIONS. && .LONG TERM /SUNDAY NIGHT THROUGH SATURDAY/... HIGH PRESSURE WILL GRADUALLY BUILD OVER THE REGION ON MONDAY AS LOW PRESSURE PULLS AWAY TO THE EAST. EXPECT MOSTLY CLOUDY SKIES MONDAY MORNING TO GIVE WAY TO SUNSHINE IN THE AFTERNOON WITH VARIABLE CLOUDS LINGERING IN THE MOUNTAINS. LOOKING FOR HIGHS FROM THE MID 20S NORTH TO THE MID 30S SOUTH. HIGH PRESSURE WILL SHIFT OFFSHORE MONDAY EVENING WITH RETURN FLOW PUMPING WARMER AIR BACK INTO THE REGION OVERNIGHT. WARM FRONT CROSSING SOUTHERN CANADA WILL BRING VARIABLE HIGH CLOUDS OVERNIGHT BUT EXPECT ANY SNOW SHOWER ACTIVITY GENERALLY REMAIN NORTH OF THE FORECAST AREA. A COLD FRONT APPROACHING FROM THE NORTHWEST WILL BRING INCREASING CLOUDS AND A CHANCE OF RAIN OR SNOW SHOWERS TO THE REGION ON TUESDAY. SHORTWAVE LIFTING NORTHEAST OUT OF THE OHIO VALLEY WILL TRACK NORTHEAST ALONG THIS BOUNDARY AS IT STALLS OVER NEW ENGLAND TUESDAY NIGHT. GFS NOW IN WITH A MUCH COLDER SOLUTION WITH LOW PRESSURE SOUTH OF NEW ENGLAND TUESDAY NIGHT...MOVING INTO THE MARITIMES ON WEDNESDAY. WILL LIKELY SEE SOME ADJUSTMENTS TO TIMING AND TRACK THROUGH THE WEEKEND SO NOT JUMPING ON THE LATEST GUIDANCE AT THIS POINT...BUT DOES APPEAR LIKELY WE`LL SEE SOME SIGNIFICANT PRECIPITATION TUESDAY NIGHT AND WEDNESDAY. LOW PRESSURE FORECAST TO SHIFT INTO THE MARITIMES WEDNESDAY NIGHT AS HIGH PRESSURE BUILDS IN FROM THE WEST. WILL SEE PRECIPITATION ENDING AND CLEARING SKIES WEDNESDAY AFTERNOON...SETTING UP A CLEAR AND CHILLY NIGHT. HIGH PRESSURE WILL HOLD OVER THE REGION ON THURSDAY WITH MOSTLY SUNNY SKIES AND LIGHT WINDS ALONG WITH SEASONABLE TEMPS. NEXT SHORTWAVE APPROACHES FROM THE WEST ON FRIDAY BRINGING INCREASING CLOUDS AND A CHANCE OF SNOW FOR SOUTHERN AREAS. LOW PRESSURE WILL FADE OVER THE GREAT LAKES AS A SECONDARY AREA OF LOW PRESSURE DEVELOPS SOUTH OF NEW ENGLAND AND LIFTS NORTHEAST. AT THIS POINT LOOKS LIKE THE BULK OF THE QPF FALLS OUT ACROSS SOUTHERN NEW ENGLAND AND OFFSHORE...BUT PLENTY OF TIME FOR CHANGES. && .AVIATION /06Z SUNDAY THROUGH THURSDAY/... SHORT TERM...VFR TONIGHT THROUGH MUCH OF SUNDAY MORNING. LOCALLY LOWER CONDITIONS MAY DEVELOP ON THE COAST DURING THE MORNING DUE TO SNOW SHOWERS. SNOW SQUALLS MAY BRIEFLY REDUCE VSBYS TO BELOW 1/2 MILE SUNDAY EVENING. LONG TERM...VFR MONDAY THROUGH TUESDAY. IFR/LIFR VSBY AND CEILINGS DEVELOPING TUESDAY NIGHT...IMPROVING WEDNESDAY AFTERNOON. VFR WEDNESDAY NIGHT AND THURSDAY. && .MARINE... SHORT TERM...WINDS AND SEAS CONTINUE TO DIMINISH THIS EVENING WITH HIGH PRESSURE BUILDING OVERHEAD. SWLY FLOW DEVELOPS SUNDAY AFTERNOON AND EVENING...AND WILL LIKELY GUST TO AROUND 30 KT WITH BUILDING SEAS. THEREFORE...A SCA HAS BEEN ISSUED TO COVER THIS. LONG TERM...SCA WINDS LIKELY MONDAY...DIMINISHING IN THE AFTERNOON. GALES POSSIBLE LATE TUESDAY NIGHT INTO WEDNESDAY. && .GYX WATCHES/WARNINGS/ADVISORIES... ME...NONE. NH...NONE. MARINE...SMALL CRAFT ADVISORY FROM 2 PM SUNDAY TO 5 AM EST MONDAY FOR ANZ150>154. && $$ ES
AREA FORECAST DISCUSSION
NWS TWIN CITIES/CHANHASSEN MN
250 PM CST SUN DEC 25 2011 .DISCUSSION... OUR STRETCH OF QUIET AND PREDOMINANTLY MILD WEATHER LOOKS TO CONTINUE THROUGH THE FORESEEABLE FUTURE... WITH ONLY A FEW MINOR SYSTEMS WITH WHICH TO BE CONCERNED. THERE ARE AT LEAST SOME INDICATIONS FOR A BIT OF ACTIVITY DURING THE LATTER HALF OF THE WEEK AS A FEW SYSTEMS TRACK A BIT CLOSER TO US... ALTHOUGH INDICATIONS ARE THAT THEIR IMPACT MAY PRIMARILY BE FELT TO OUR NORTH. THE MAIN WEATHER ITEM OF CONCERN LOOKS TO BE SOME GUSTY WINDS TONIGHT INTO MONDAY AS THE PRESSURE GRADIENT SIGNIFICANTLY TIGHTENS OVER THE AREA WITH A 992MB SURFACE LOW TRACKING EAST THROUGH SOUTHERN CANADA. THE GFS AND NAM BOTH SUGGEST WINDS AOA 65 KT IN THE BOTTOM FEW THOUSAND FEET LATE TONIGHT INTO EARLY MONDAY. ALTHOUGH THESE WON/T BE REALIZED AT THE SURFACE... LOCATIONS IN THE WEST CENTRAL AND SOUTHWEST PORTION OF THE CWFA SHOULD SEE SOME GUSTS ABOVE 40KT DURING THAT TIME FRAME GIVEN MORE FAVORABLE TOPOGRAPHIC CONDITIONS IN THAT AREA... NAMELY THEIR EXPOSURE AND POTENTIAL FOR DOWNSLOPE ENHANCEMENT IN THE LEE OF THE BUFFALO RIDGE. GIVEN THIS POTENTIAL... WILL BE ISSUING A WIND ADVISORY FOR THE OVERNIGHT INTO THE MORNING HOURS FOR PART OF THE WEST CENTRAL AND SOUTHWEST CWFA. THE REMAINDER OF THE AREA SHOULD SEE GUSTY WINDS DEVELOP AS WELL... BUT AT THIS POINT THE EXPECTATION IS THAT THEY WILL REMAIN BELOW ADVISORY LEVELS OVER THE REMAINDER OF THE AREA. IN THE BIG PICTURE... WATER VAPOR IMAGERY AND RUC UPPER AIR ANALYSES SHOW A DEPARTING SHORTWAVE MOVING THROUGH THE GREAT LAKES... WITH THE NEXT FEATURE ASCENDING THE RIDGE OVER THE WESTERN STATES AND SOUTHWEST CANADA. THIS SHORTWAVE WILL HELP DRIVE THE AFOREMENTIONED SURFACE LOW ACROSS SOUTHERN CANADA ON MONDAY... WITH GUSTY SOUTHWEST WINDS AND SIGNIFICANT WARM ADVECTION ACROSS OUR AREA. HIGH TEMPERATURES WILL BE WELL ABOVE NORMAL ONCE AGAIN... AND A FEW SPOTS COULD APPROACH RECORDS. GIVEN SOME UNCERTAINTY ON THE DEGREE OF MID AND HIGH CLOUDS DID NOT GO WITH EXCEEDINGLY HIGH VALUES... ALTHOUGH STILL ROUGHLY 20 DEGREES ABOVE NORMAL... SO THE OVERNIGHT SHIFT AND SHORT TERM FORECASTS ON MONDAY WILL LIKELY NEED TO MAKE SOME REFINEMENTS. THE COLD FRONT WILL PUSH ACROSS THE AREA DURING THE AFTERNOON AND EVENING HOURS... AND LOOKS TO COME THROUGH PCPN-FREE. COOLER... YET STILL ABOVE NORMAL... TEMPERATURES LOOK TO RETURN FOR TUESDAY. INCLUDED A FEW FLURRIES FOR TUESDAY NIGHT INTO WEDNESDAY AS A LOBE OF WARM ADVECTION AHEAD OF THE NEXT SYSTEM SWINGS ACROSS THE AREA. THE NAM... GFS... SREF... AND ECMWF ALL WRING OUT SOME LIGHT PCPN WITH THIS FEATURE... AND THERE IS A NARROW AXIS OF REDUCED CONDENSATION PRESSURE DEFICITS COINCIDENT WITH THE BETTER ISENTROPIC ASCENT... SO MAY NEED TO EVENTUALLY INTRODUCE SOME POPS. THE BAROCLINIC ZONE LOOKS TO LINGER OVER THE AREA AS ANOTHER WEAK SHORTWAVE SWINGS BY WEDNESDAY NIGHT... SO KEPT SO LOW CHANCE POPS TO ACCOUNT FOR THAT. A MORE SUBSTANTIAL FEATURE CONTINUES TO BE ADVERTISED BY THE GFS AND ECMWF DURING THE THURSDAY NIGHT-FRIDAY TIME FRAME. BOTH SUGGEST A DECENT NORTHWEST-SOUTHEAST ORIENTED AREA OF MID LEVEL FRONTOGENESIS ON THE NORTH SIDE OF A 995MB-ISH SURFACE LOW WHICH TRACKS FROM CENTRAL NORTH DAKOTA THROUGH THE TWIN CITIES AREA AND EVENTUALLY TO CENTRAL LAKE MICHIGAN. THERE IS A FAIRLY PROLONGED PERIOD OF WEST TO SOUTHWESTERLY FLOW IN PLACE BEFORE THIS SYSTEM MOVES INTO THE AREA... SO WE SHOULD HAVE A BETTER CHANCE OF SEEING DEEP SATURATION AND SOME HEALTHIER PCPN AMOUNTS... AND INDEED BOTH THE GFS AND ECMWF MANAGE TO PRODUCE MAX AMOUNTS NEAR A QUARTER OF AN INCH. THE BIG QUESTION WILL BE WHERE EXACTLY THE BAND OF PCPN... WHICH SHOULD BE IN THE FORM OF SNOW... WILL SETUP. AT THE CURRENT TIME IT LOOKS LIKE THE BEST CHANCE WOULD ALONG AND NORTH OF THE I-94 CORRIDOR GIVEN THE FORECAST POSITION OF THE UPPER JET AND TRACK OF THE SURFACE LOW TOGETHER WITH THE MID-LEVEL TEMPERATURE GRADIENT. OF COURSE... MUCH CAN CHANGE WITH SOMETHING THAT IS EXPECTED 4-5 DAYS FROM NOW... SO AT THIS POINT JUST INCLUDED CHANCE POPS FOR MUCH OF THE AREA... WITH HIGHER VALUES OVER THE NORTHERN FORECAST AREA. IT CERTAINLY DOESN/T LOOK TO BE A BARN-BURNER... BUT AT THIS POINT ANY SORT OF ORGANIZED ACCUMULATING PCPN IS ATTENTION GRABBING. A DECENT SHOT OF COLD AIR LOOKS TO ARRIVE IN THE WAKE OF THIS FEATURE... PERHAPS PRODUCING TEMPERATURES THAT ARE ONLY 5-10 DEGREES ABOVE NORMAL. OTHERWISE... IT LOOKS TO BE MAINLY DRY AS WE HEAD THROUGH THE UPCOMING WEEKEND ALTHOUGH THERE ARE HINTS OF ANOTHER WEAK SHOT OF PCPN SLIPPING THROUGH LATE SATURDAY INTO SUNDAY. && .AVIATION.../18Z TAF ISSUANCE/ NO SIGNIFICANT AVIATION CONCERN...EXCEPT GUSTY WINDS OVER THE NEXT 24 HOURS. SOUTH-SOUTHWEST WINDS INCREASING OVER THE UPPER MIDWEST AHEAD OF THE SURFACE TROUGH TONIGHT. PRESSURE GRADIENT WILL TIGHTEN OVER THE FORECAST AREA LATER TONIGHT...WITH OCCASIONAL GUSTS TO AROUND 25 KNOTS. WEATHER CONDITIONS WILL REMAIN VFR WITH CLOUDS GENERALLY OVER MUCH OF THE AREA OVER 20 THOUSAND FEET AGL. SOME SCATTERED CUMULUS AROUND 3000 FEET AGL OVER WEST CENTRAL WISCONSIN THIS AFTERNOON. ONLY PROBLEM TODAY WILL BE GUSTY WEST WINDS AROUND 20 KNOTS. GRADIENT WILL RELAX LATER TODAY BEFORE TIGHTEN AGAIN TONIGHT. MSP...VFR CONDITIONS WILL PREVAIL THROUGH THE PERIOD. ONLY AVIATION CONCERN WILL BE GUSTY SOUTH-SOUTHWEST WINDS DEVELOPING LATER TONIGHT/MONDAY MORNING. && .MPX WATCHES/WARNINGS/ADVISORIES... MN...WIND ADVISORY FROM MIDNIGHT TONIGHT TO NOON CST MONDAY FOR BROWN- LAC QUI PARLE-REDWOOD-WATONWAN-YELLOW MEDICINE. WI...NONE. && $$
AREA FORECAST DISCUSSION
NWS DULUTH MN
1148 AM CST SUN DEC 25 2011 .AVIATION...18Z TAFS. MVFR CIGS COVER THE TAF SITES. HOWEVER...KBRD WILL SCT OUT BY 20Z WITH CLEARING LINE JUST TO THE SW. ELSEWHERE...CONTINUE THE THINKING OF CLEARING OCCURRING AT THE OTHER SITES BETWEEN 21Z AND 23Z REACHING VFR. SFC RIDGE AXIS MOVES OVERHEAD OVERNIGHT. MEANWHILE...LLWS POTENTIAL INCREASES FROM 05Z TO 07Z AT ALL SITES AS STRONG WAA OCCURS IN THE LOWEST 2K FT AND UP AS WIND SPEED INCREASES AOA 40KT AND PERSISTS THROUGH THE TAF CYCLE. && .PREV DISCUSSION... /ISSUED 1026 AM CST SUN DEC 25 2011/ UPDATE... AT 1615 UTC...THE NORTHLAND WAS IN NORTHWEST FLOW. THERE WAS A WIDESPREAD BLANKET OF OVERCAST STRATUS COVERING OF THE MOST OF THE FA...AS WELL AS UPSTREAM IN EASTERN MANITOBA AND ONTARIO. OBSERVATIONS WERE GENERALLY RECORDING NORTHWEST WINDS BETWEEN 10 AND 20 MPH WITH GUSTS UP TO ABOUT 25 MPH. A RIDGE OF HIGH PRESSURE AND HIGH CIRRUS CLOUDS WERE IN THE HIGH PLAINS OF THE WESTERN DAKOTAS AND MONTANA AND APPROACHING THE NORTHLAND. LOOKING UPSTREAM AT THE OVERCAST STRATUS DECK POURING OUT OF CANADA...IT IS REMINISCENT OF A SITUATION EARLY LAST WEEK. THINK THIS WILL BE ANOTHER CASE WHERE THE FORECASTED AFTERNOON CLEARING WILL HAVE A DIFFICULT TIME DEVELOPING. THINK THE LOWER CONVECTIVE TEMPERATURES IN THIS COLD NORTHWEST FLOW WILL ALLOW THE SUN TO ATTEMPT TO FILL ANY CLEARING THAT TRIES TO FORM BY DEVELOPING REINFORCING STRATOCUMULUS. STILL PLANNING ON SEEING CLEARING...BUT THINK IT WILL BE SIGNIFICANTLY DELAYED...ESPECIALLY ACROSS THE EASTERN FA. LEANED ON THE WEB BASED HRRR MODEL...WHICH DID FAIRLY WELL WITH THE SIMILAR SITUATION LAST WEEK. MADE SOME TWEAKS TO TEMPERATURES...ESPECIALLY SINCE SOME LOCATIONS WERE PROBABLY ALREADY NEAR THEIR FORECASTED HIGH TEMPERATURES. THE OVERCAST SKIES WILL PREVENT MUCH MORE WARMING TODAY...EXCEPT ACROSS THE WESTERN FA WHICH WILL SEE BETTER CLEARING THIS AFTERNOON. INCREASED WINDS A BIT TOO...INCLUDING WIND GUSTS. WILL KEEP AN EYE ON THESE CLOUD TRENDS THROUGH THE AFTERNOON. HAVE SOME DOUBTS ABOUT WHETHER THE TWEAKED SKY COVER FORECAST DELAYED THE CLEARING ENOUGH. PREV DISCUSSION... /ISSUED 610 AM CST SUN DEC 25 2011/ AVIATION...12Z TAFS WIDESPREAD MVFR CONDITIONS WITH -SHSN OR FLURRIES WILL BE FOUND THROUGH MID MORNING...THEN IMPROVING CONDITIONS AND CLEARING SKIES IN THE AFTERNOON. SFC WINDS WILL REMAIN GUSTY OUT OF THE NW THROUGH 18Z...THEN DIMINISH AND BECOME VARIABLE IN THE LATE AFTERNOON AND EVENING. WINDS WILL INCREASE OUT OF THE SOUTH TO SOUTHWEST LATE...MAINLY AFTER 08Z. INTRODUCED LLWS TO ALL TERMINALS OVERNIGHT. PREV DISCUSSION... /ISSUED 357 AM CST SUN DEC 25 2011/ SHORT TERM...AMPLIFYING SHORTWAVE TROF... ACCOMPANIED BY 120KT 30H JET IS SWINGING ACROSS CWA EARLY THIS MORNING. MAJORITY OF SYNOPTIC SCALE FORCING IS SPREADING FROM ARROWHEAD/IRON RANGE SOUTHEAST INTO NW WISCONSIN. SNOW HAS BEEN MOST PERSISTENT WITHIN COUPLED DGZ/DEEP LYR MOISTURE NORTH OF A KFOZ TO KTWM LINE AS OF EARLY THIS MORNING. AT SFC..A COLD FRONT STRETCHES FROM NEAR HUDSON BAY SOUTHWEST TO NEAR CYQT AND WEST INTO SRN MANITOBA. NORTH OF THIS BDRY...TEMPS/DEWPTS MORE REFLECTIVE OF POLAR AIR WHILE SOUTH OF THE BDRY AIR HAS A MORE MODIFIED POLAR/PACIFIC TYPE SOURCE REGION. TODAY...PROGRESSIVE NATURE OF UPPER FLOW KEEPS CURRENT SFC/MID LVL SYSTEM MOVING EAST FAIRLY QUICKLY TODAY. EXPECT SNOW TO CONTINUE OVER NWRN WISC THROUGH MID MORNING WHILE DECREASING OVER MN ZONES. COND PRESS DEFICITS SUGGEST MOSTLY CLOUDY CONDITIONS OVER MN THRU 18Z WITH CLEARING FROM WEST TO EAST IN THE AFTN. MOMENTUM TRANSFER WILL INCREASE WITH CLOUDS DIMINISHING SO EXPECT A PERIOD OF GUSTY NW WINDS DEVELOPING. LOW LEVEL THERMAL FIELDS DO NOT SUPPORT SIGNIFICANT LAKE INDUCED INSTABILITY. HOWEVER SYNOPTIC SCALE ASCENT COMBINED WITH TERRAIN LIFT SHOULD ALLOW SOME 1 TO 2 INCH ACCUMULATION OVER GOGEBIC RANGE THIS MORNING. SNOW SHOULD DIMINISH BY 21Z OVER ERN WISC SNOWBELT. CLOUDS AND LOW LVL COLD ADVECTION SHOULD KEEP TEMP CLIMB TO A MINIMUM OVER ERN CWA TODAY. MILDEST READINGS EXPECTED ACROSS SWRN CWA WITH MORE SUNSHINE. TONIGHT/TOMORROW...MID LVL RIDGE MOVES ACROSS CWA TONIGHT WITH WARM ADVECTION REGIME INCREASING IN STRENGTH. USED BC TEMPS CONSIDERING ANOMALOUS PATTERN AND LIMITED SNOW COVER. MAY STILL NEED TO ADJUSTING MIN TEMPS UPWARDS. SHOULD SEE A SHIELD OF MID/HIGH CLOUDS TRAVERS FROM WEST TO EAST DURING THE DAY MONDAY. MAX TEMPS MAY REACH 15 TO 20 DEGREES ABOVE NORMS. INTENSE SFC LOW WILL SWEEP ACROSS SRN MAN INTO SCTRL ONTARIO BY 0Z TUE. WILL HOLD OFF ON PRECIP FOR NOW BUT LATEST SREF/GEM INDICATE EXTENDED....MONDAY NIGHT THROUGH SATURDAY TEMPERATURES WILL RAPIDLY FALL MON NIGHT/TUES AS THE TROUGH DEPARTS TO THE EAST AND WINDS TURN OUT OF THE NW. LATEST NAM/ECMWF/GFS CONTINUE TO SHOW AGREEMENT THAT H85 READINGS FALL ON THE ORDER OF 10C FROM 00Z THROUGH 12Z TUESDAY. THE CYCLONIC FLOW WILL KEEP SMALL CHC FOR LINGERING -SHSN ACROSS THE NRN/ERN ZONES THROUGH TUES. A FAST MOVING SFC RIDGE WILL PASS OVER THE REGION TUES AFTN/EVENING BEFORE WINDS INCREASE OUT OF THE SOUTH LATE TUES NIGHT AHEAD OF APPROACHING WAVE DROPPING SE OUT OF MANITOBA. TIMING OF THE RIDGE PASSING WILL HAVE SIGNIFICANT EFFECT ON OVERNIGHT LOWS TUES NIGHT WITH CLEARING AND LIGHT WINDS ASSOCIATED WITH THE RIDGE POTENTIALLY DROPPING THE TEMPS INTO THE SINGLE DIGITS IN THE NE ZONES...THEN RISING LATE WITH THE RETURN FLOW. LONG TERM MODELS BEGIN TO HAVE LARGE DIFFERENCES PAST DAY 4. HAVE CHC POPS AT THE END OF THE WEEK WITH SOME CONTINUITY THAT A FAST MOVING WAVE TRANSLATES OVER THE REGION. HOWEVER...THE STRENGTH AND TIMING OF THIS SYSTEM AND POTENTIAL FOR ANY SNOW ACCUM REMAIN HIGHLY UNCERTAIN. && .POINT TEMPS/POPS... DLH 34 23 38 24 / 20 0 0 10 INL 33 22 37 16 / 20 0 10 20 BRD 37 25 42 23 / 10 0 0 0 HYR 36 20 39 24 / 20 0 0 10 ASX 36 23 40 28 / 40 0 0 10 && .DLH WATCHES/WARNINGS/ADVISORIES... MN...NONE. WI...NONE. LS...SMALL CRAFT ADVISORY UNTIL 4 PM CST THIS AFTERNOON FOR LSZ146- 147. && $$ SHORT TERM...GROCHOCINSKI AVIATION...GSF
AREA FORECAST DISCUSSION
NWS DULUTH MN
1026 AM CST SUN DEC 25 2011 .UPDATE... AT 1615 UTC...THE NORTHLAND WAS IN NORTHWEST FLOW. THERE WAS A WIDESPREAD BLANKET OF OVERCAST STRATUS COVERING OF THE MOST OF THE FA...AS WELL AS UPSTREAM IN EASTERN MANITOBA AND ONTARIO. OBSERVATIONS WERE GENERALLY RECORDING NORTHWEST WINDS BETWEEN 10 AND 20 MPH WITH GUSTS UP TO ABOUT 25 MPH. A RIDGE OF HIGH PRESSURE AND HIGH CIRRUS CLOUDS WERE IN THE HIGH PLAINS OF THE WESTERN DAKOTAS AND MONTANA AND APPROACHING THE NORTHLAND. LOOKING UPSTREAM AT THE OVERCAST STRATUS DECK POURING OUT OF CANADA...IT IS REMINISCENT OF A SITUATION EARLY LAST WEEK. THINK THIS WILL BE ANOTHER CASE WHERE THE FORECASTED AFTERNOON CLEARING WILL HAVE A DIFFICULT TIME DEVELOPING. THINK THE LOWER CONVECTIVE TEMPERATURES IN THIS COLD NORTHWEST FLOW WILL ALLOW THE SUN TO ATTEMPT TO FILL ANY CLEARING THAT TRIES TO FORM BY DEVELOPING REINFORCING STRATOCUMULUS. STILL PLANNING ON SEEING CLEARING...BUT THINK IT WILL BE SIGNIFICANTLY DELAYED...ESPECIALLY ACROSS THE EASTERN FA. LEANED ON THE WEB BASED HRRR MODEL...WHICH DID FAIRLY WELL WITH THE SIMILAR SITUATION LAST WEEK. MADE SOME TWEAKS TO TEMPERATURES...ESPECIALLY SINCE SOME LOCATIONS WERE PROBABLY ALREADY NEAR THEIR FORECASTED HIGH TEMPERATURES. THE OVERCAST SKIES WILL PREVENT MUCH MORE WARMING TODAY...EXCEPT ACROSS THE WESTERN FA WHICH WILL SEE BETTER CLEARING THIS AFTERNOON. INCREASED WINDS A BIT TOO...INCLUDING WIND GUSTS. WILL KEEP AN EYE ON THESE CLOUD TRENDS THROUGH THE AFTERNOON. HAVE SOME DOUBTS ABOUT WHETHER THE TWEAKED SKY COVER FORECAST DELAYED THE CLEARING ENOUGH. && .PREV DISCUSSION... /ISSUED 610 AM CST SUN DEC 25 2011/ AVIATION...12Z TAFS WIDESPREAD MVFR CONDITIONS WITH -SHSN OR FLURRIES WILL BE FOUND THROUGH MID MORNING...THEN IMPROVING CONDITIONS AND CLEARING SKIES IN THE AFTERNOON. SFC WINDS WILL REMAIN GUSTY OUT OF THE NW THROUGH 18Z...THEN DIMINISH AND BECOME VARIABLE IN THE LATE AFTERNOON AND EVENING. WINDS WILL INCREASE OUT OF THE SOUTH TO SOUTHWEST LATE...MAINLY AFTER 08Z. INTRODUCED LLWS TO ALL TERMINALS OVERNIGHT. PREV DISCUSSION... /ISSUED 357 AM CST SUN DEC 25 2011/ SHORT TERM...AMPLIFYING SHORTWAVE TROF... ACCOMPANIED BY 120KT 30H JET IS SWINGING ACROSS CWA EARLY THIS MORNING. MAJORITY OF SYNOPTIC SCALE FORCING IS SPREADING FROM ARROWHEAD/IRON RANGE SOUTHEAST INTO NW WISCONSIN. SNOW HAS BEEN MOST PERSISTENT WITHIN COUPLED DGZ/DEEP LYR MOISTURE NORTH OF A KFOZ TO KTWM LINE AS OF EARLY THIS MORNING. AT SFC..A COLD FRONT STRETCHES FROM NEAR HUDSON BAY SOUTHWEST TO NEAR CYQT AND WEST INTO SRN MANITOBA. NORTH OF THIS BDRY...TEMPS/DEWPTS MORE REFLECTIVE OF POLAR AIR WHILE SOUTH OF THE BDRY AIR HAS A MORE MODIFIED POLAR/PACIFIC TYPE SOURCE REGION. TODAY...PROGRESSIVE NATURE OF UPPER FLOW KEEPS CURRENT SFC/MID LVL SYSTEM MOVING EAST FAIRLY QUICKLY TODAY. EXPECT SNOW TO CONTINUE OVER NWRN WISC THROUGH MID MORNING WHILE DECREASING OVER MN ZONES. COND PRESS DEFICITS SUGGEST MOSTLY CLOUDY CONDITIONS OVER MN THRU 18Z WITH CLEARING FROM WEST TO EAST IN THE AFTN. MOMENTUM TRANSFER WILL INCREASE WITH CLOUDS DIMINISHING SO EXPECT A PERIOD OF GUSTY NW WINDS DEVELOPING. LOW LEVEL THERMAL FIELDS DO NOT SUPPORT SIGNIFICANT LAKE INDUCED INSTABILITY. HOWEVER SYNOPTIC SCALE ASCENT COMBINED WITH TERRAIN LIFT SHOULD ALLOW SOME 1 TO 2 INCH ACCUMULATION OVER GOGEBIC RANGE THIS MORNING. SNOW SHOULD DIMINISH BY 21Z OVER ERN WISC SNOWBELT. CLOUDS AND LOW LVL COLD ADVECTION SHOULD KEEP TEMP CLIMB TO A MINIMUM OVER ERN CWA TODAY. MILDEST READINGS EXPECTED ACROSS SWRN CWA WITH MORE SUNSHINE. TONIGHT/TOMORROW...MID LVL RIDGE MOVES ACROSS CWA TONIGHT WITH WARM ADVECTION REGIME INCREASING IN STRENGTH. USED BC TEMPS CONSIDERING ANOMALOUS PATTERN AND LIMITED SNOW COVER. MAY STILL NEED TO ADJUSTING MIN TEMPS UPWARDS. SHOULD SEE A SHIELD OF MID/HIGH CLOUDS TRAVERS FROM WEST TO EAST DURING THE DAY MONDAY. MAX TEMPS MAY REACH 15 TO 20 DEGREES ABOVE NORMS. INTENSE SFC LOW WILL SWEEP ACROSS SRN MAN INTO SCTRL ONTARIO BY 0Z TUE. WILL HOLD OFF ON PRECIP FOR NOW BUT LATEST SREF/GEM INDICATE EXTENDED....MONDAY NIGHT THROUGH SATURDAY TEMPERATURES WILL RAPIDLY FALL MON NIGHT/TUES AS THE TROUGH DEPARTS TO THE EAST AND WINDS TURN OUT OF THE NW. LATEST NAM/ECM/GFS CONTINUE TO SHOW AGREEMENT THAT H85 READINGS FALL ON THE ORDER OF 10C FROM 00Z THROUGH 12Z TUESDAY. THE CYCLONIC FLOW WILL KEEP SMALL CHC FOR LINGERING -SHSN ACROSS THE NRN/ERN ZONES THROUGH TUES. A FAST MOVING SFC RIDGE WILL PASS OVER THE REGION TUES AFTRN/EVENING BEFORE WINDS INCREASE OUT OF THE SOUTH LATE TUES NIGHT AHEAD OF APPROACHING WAVE DROPPING SE OUT OF MANITOBA. TIMING OF THE RIDGE PASSING WILL HAVE SIGNIFICANT EFFECT ON OVERNIGHT LOWS TUES NIGHT WITH CLEARING AND LIGHT WINDS ASSOCIATED WITH THE RIDGE POTENTIALLY DROPPING THE TEMPS INTO THE SINGLE DIGITS IN THE NE ZONES...THEN RISING LATE WITH THE RETURN FLOW. LONG TERM MODELS BEGIN TO HAVE LARGE DIFFERENCES PAST DAY 4. HAVE CHC POPS AT THE END OF THE WEEK WITH SOME CONTINUITY THAT A FAST MOVING WAVE TRANSLATES OVER THE REGION. HOWEVER...THE STRENGTH AND TIMING OF THIS SYSTEM AND POTENTIAL FOR ANY SNOW ACCUM REMAIN HIGHLY UNCERTAIN. && .POINT TEMPS/POPS... DLH 34 23 38 24 / 20 0 0 10 INL 33 22 37 16 / 20 0 10 20 BRD 37 25 42 23 / 10 0 0 0 HYR 34 20 39 24 / 20 0 0 10 ASX 34 23 40 28 / 40 0 0 10 && .DLH WATCHES/WARNINGS/ADVISORIES... MN...NONE. WI...NONE. LS...SMALL CRAFT ADVISORY UNTIL 4 PM CST THIS AFTERNOON FOR LSZ146- 147. && $$ SHORT TERM...GROCHOCINSKI
AREA FORECAST DISCUSSION...UPDATED AVIATION
NWS ST LOUIS MO
554 PM CST MON DEC 26 2011 .DISCUSSION... /240 PM CST MON DEC 26 2011/ RAIN IS OVERSPREADING THE AREA FROM THE SOUTH...MORE OR LESS ON TIME THIS AFTERNOON. HAVE HAD A FEW REPORTS OF A LITTLE SLEET MIXED IN WITH THE RAIN...BUT THE SLEET IS MELTING VERY QUICKLY AND SHOULD HAVE NO IMPACT. THE MAIN SLUG OF MOISTURE IS JUST MOVING UP INTO SOUTHERN MISSOURI FROM ARKANSAS AND LIKELY TO CATEGORICAL POPS STILL LOOK VERY GOOD FOR MUCH OF EASTERN MISSOURI AND SOUTHERN ILLINOIS. HOWEVER...LATEST GUIDANCE CONTINUES TO LOOK IFFY FOR MUCH SNOW. TOP-DOWN METHOD ON BUFKIT SOUNDINGS FROM THE NAM...GFS...LOCAL WRF...AND THE RUC SHOW THAT BY THE TIME THE LOWER ATMOSPHERE COOLS ENOUGH TO SUPPORT SNOW...THE TROF WILL BE LIFTING OUT AND AWAY FROM THE REGION AND DRY AIR WILL BE POURING IN ALOFT. CAN`T ENTIRELY RULE OUT SNOW SINCE TIMING THE DRY AND COLD AIR WILL BE CRITICAL...BUT HAVE REDUCED ACCUMULATIONS BELOW 1 INCH...AND HAVE CHANGED WORDING FROM LIKELY TO CATEGORICAL RAIN/SNOW...TO RAIN AND A CHANCE OF SNOW. CARNEY SRN STORM SYSTEM WILL BE NEARLY BY THE FA BY TUESDAY MORNING...AND BY THIS TIME...WILL BE AN OPEN WAVE. CONSIDERING HOW THERE IS NOT MUCH COLD AIR WITH THIS SYSTEM TO BEGIN WITH (N.B. COLD AIR HAS BEEN HARD TO COME BY SO FAR THIS LATE AUTUMN AND WINTER) AND SFC TEMPS WILL BE IN THE MID 30S...SNOW AS A GENERAL RULE WILL BE HARD TO COME BY. MODEL SOUNDINGS FROM ALL GUIDANCE SUGGESTS THIS AS WELL... ALTHOUGH WBZ VALUES AT ITS LOWEST POINT EARLY TUESDAY MORNING WILL NOT BE TOO FAR OFF FROM BEING ABLE TO RESULT IN SNOW. SO FOR THIS REASON...TO INCORPORATE A SMALL AMOUNT OF POTENTIAL MODEL ERROR... HAVE RETAINED MENTION OF SNOW...BUT AS A MIX WITH RAIN THROUGHOUT THE CONCLUSION OF THIS EVENT. ANY ADDITIONAL SNOW AMOUNTS TUESDAY MORNING WILL BE A DUSTING OR LESS AS IT LOOKS AT THIS TIME. NRN STREAM STORM SYSTEM THAT WILL BE RIGHT ON THE HEELS OF THE SRN STORM WILL PRODUCE NOTHING MORE THAN SOME ADDITIONAL CLOUDS. ANOTHER WEAK UPPER LEVEL SYSTEM WILL SLIDE THRU LATE TUESDAY NIGHT AND WEDNESDAY MORNING BUT WILL CARRY LITTLE MOISTURE WITH IT AND WILL BE TOO WEAK TO PRODUCE ANY PCPN. MOS BLENDS LOOK REASONABLE FOR MAX TEMPS TUESDAY AND WEDNESDAY. WENT AT OR ABOVE THE WARMEST MOS TEMPS FOR MINS WEDNESDAY NIGHT WITH FAIRLY STOUT SW FLOW THAT SHOULD CARRY INTO A PRETTY MILD DAY ON THURSDAY AS TEMPS SURGE INTO THE 50S. A RATHER PROGRESSIVE FLOW WILL DOMINATE THE MEDIUM RANGE FRIDAY THRU MONDAY AND WILL SIGNAL NO BIG COLD AIR OUTBREAKS (STILL) THRU THE BEGINNING OF 2012. UPPER LEVEL DISTURBANCES WILL RACE THRU AND EDGE THE FA LATE FRIDAY AND LATE SATURDAY BUT LIKE THEIR PREDECESSORS SHOULD BE TOO WEAK TO GENERATE MUCH PCPN THRU SATURDAY. BY EARLY NEXT WEEK...MOST MODELS TAKE A MUCH STRONGER SYSTEM INTO THE AREA. THE GFS IS THE EXCEPTION KEEPING THIS SYSTEM WELL TO THE N. HAVE SLIGHT CHC POPS FOR NOW UNTIL WE CAN GET SOME BETTER RUN-TO-RUN CONSISTENCY. TEMPS WILL BE AT OR ABOVE AVERAGE THRU THE PERIOD. TES && .AVIATION... /537 PM CST MON DEC 26 2011/ WIDESPREAD PRECIP WILL CAUSE DETERIORATING CONDITIONS IN STL AREA THIS EVENING...AND DETAILS ON THIS ARE IN THE STL SECTION BELOW. MEANWHILE...IT APPEARS THAT COU AND UIN AREAS WILL JUST BE BRUSHED BY THE PRECIP WITH TONIGHTS SYSTEM...AND PASSAGE OF SFC TROF IN THE 06-09Z TIME FRAME SHOULD SHUNT THE HIGHEST LOW LEVEL RH/LOWEST CIGS/VSBYS EAST OF THESE TAF LOCATIONS. FORECASTS DO HINT AT SOME LOWERING...BUT PREVAILING GROUPS MAINTAIN VFR CIGS. LOWER CLOUDS SHOULD SCOUR OUT TUESDAY MORNING...FOLLOWED BY GUSTY NW WINDS AND SCT-BKN CU/SC...ESPECIALLY IN UIN AREA. SPECIFICS FOR KSTL...SATURATION OF THE LOW LEVELS DUE TO PERSISTENT PRECIP WILL CAUSE CONDITIONS TO LOWER OVER THE AREA THIS EVENING...HOWEVER 18Z SOUNDINGS AS WELL AS 23Z NEPHANALYSIS SUGGESTS VFR CIGS AND OCNL MVFR VSBYS CAN BE EXPECTED TO HOLD FOR SEVERAL MORE HOURS. HOWEVER...THEY ALSO SUPPORT THE THINKING/TRENDS OF EARLIER FORECASTS THAT CIGS WILL LOWER TO IFR...AND MVFR VSBYS WILL BECOME DOMINATE...DURING THE 03-06Z TIME RANGE. STILL APPEARS THAT A RAIN/SNOW MIX WILL BE POSSIBLE DURING THE PREDAWN HOURS BUT LATEST GUIDANCE SUPPORTS EARLIER THINKING THAT BY THE TIME COLUMN COOLS ENOUGH TO SUPPORT SNOW THE PRECIP WILL BE WINDING DOWN. APPEARS LOW LEVEL MOISTURE/MVFR CIGS WILL BE SCOURED OUT TUESDAY MORNING WITH INCREASING NW LOW LEVEL FLOW...WITH NW WINDS GUSTING TO NEAR 30 KTS BY MIDDAY AND INTO THE AFTERNOON. TRUETT && .LSX WATCHES/WARNINGS/ADVISORIES... MO...NONE. IL...NONE. && $$ WFO LSX
AREA FORECAST DISCUSSION
NWS BINGHAMTON NY
1005 PM EST MON DEC 26 2011 .SYNOPSIS... SOUTHERLY FLOW AHEAD OF A LOW PRESSURE SYSTEM WILL BRING MILDER TEMPERATURES TO THE AREA TOMORROW. RAIN WILL MOVE INTO THE AREA TUESDAY AFTERNOON. THERE WILL BE A CHANGE OVER TO SNOW LATE TUESDAY NIGHT AS COLDER AIR MOVES BACK IN. LAKE EFFECT SNOW IS POSSIBLE ON WEDNESDAY. HIGH PRESSURE WILL BUILD IN THURSDAY. && .NEAR TERM /THROUGH TUESDAY/... 10PM UPDATE...WITH CLEAR SKIES AND THE SYSTEM NOT COMING IN UNTIL THE AFTERNOON, THE WEATHER IS QUIET. MADE LITTLE CHANGES THROUGH TOMORROW MORNING. THEN, THE ONLY CHANGES WAS TO TIMING AND SOME QPF AMOUNTS. WENT MUCH CLOSER TO HPC AMOUNTS FOR THIS SYSTEM. OTHERWISE, NO SIGNIFICANT CHANGES TO THE FORECAST. PREVIOUS DISCUSSION...VIS SATL IMAGERY SHOWS SC LAYER OVER ALL OF C NY AND NE PA. LARGE SCALE SUBSC BEHIND DEPARTING SHRT WAVE OFF THE NE COAST WILL CONT TO PUSH INVERSION DOWN AND EVENTUALLY WILL LEAD TO CLRG SKIES LATE THIS AFTERNOON AND ERLY EVENING. VIS SATL IMAGERY ALREADY SHOWG THIS IN WRN NY AND NC/NE PA. THE BACK EDGE OF THE SC LAYER CORRELATED WELL WITH THE 850 MB TEMP GRADIENT WHICH IS INDICATIVE OF THE SUBSC. USING THE LOCAL WRFARW...THIS GRADIENT MOVES THRU BTWN 21Z AND 00Z...WHILE THE RUC13 HOLDS ONTO THE COLDER H85 TEMPS IN EC NY A LITTLE LONGER. IN ANY EVENT BOTH SEEM TO SHOW SIGNS THAT THIS CLRG WILL TAKE A BIT LONGER IN EC NY...WHERE THERE IS HIGHER TERRAIN. THIS MAKES SENSE AND WILL HOLD ONTO CLDS A LITTLE LONGER IN THESE AREAS. REST OF AREA SEES CLRG FOR A TIME THIS EVENING. AFTER THE CLDS CLEAR OUT THIS EVENING...HIGHER CLDS FROM THE NEXT SYSTEM BEGIN TO SPREAD ACROSS NY AND PA. THE SFC RDG AXIS IS E OF THE REGION TONIGHT AS THE NEXT SYSTEM RAPIDLY APPRCHES FROM THE SRN PLAINS AND UPR MIDWEST. THE LL FLO WILL TURN SWRLY AND SHUD KEEP TEMPS FROM BOTTOMING OUT MUCH BELOW 30 MOST PLACES. THE EXCEPTION IS IN NE PA/SERN NY WHERE THE WINDS WILL REMAIN LIGHT ENUF WITH CLR SKIES. THUS MINS WILL BE HIGHER IN THE NW CWA LOW 30S AND LOWER IN THE SE CWA MID TO UPPER 20S OR SO. FOR TUESDAY...CLDS WILL INCREASE THRU THE DAY AS STRG WAA/ISEN LIFT TAKES PLACE THRU A DEEPER AND DEEPER LAYER AS THE DAY PROGRESSES. TEMPS FROM THE SFC THRU 850 MB WILL BE WARM ENUF FOR ALL RAIN ENTIRE CWA. ALL SYNOPTIC SCALE MODELS INDICATE THAT THE RAIN WILL MOVE IN DURING THE AFTERNOON. WILL RAMP POPS UP BTWN 18Z TUE AND 00Z WED. && .SHORT TERM /TUESDAY NIGHT THROUGH WEDNESDAY NIGHT/... THE 12Z EURO...18Z NAM...12Z GFS HAVE TRENDED MORE TOWARD THE WEST WITH THE SFC LO AND ALL INDICATE THAT THE 850 MB LOW TRACKS TO WRN NY BY 00Z WED. THIS WILL ALLOW 850 MB TEMPS TO CLIMB WELL ABV FRZG AS THE PRECIP WORKS IN. WITH BNDRY LAYER TEMPS EXPECTED ABV FRZG...PRECIP WILL BE MAINLY RAIN AT THE ONSET. IN ADDTN...WITH THIS MORE WRN TRACK...THE DRY SLOT WITH THE DEVELOPING CYCLONE MOVES RIGHT THRU NE PA AND C NY TUE EVE. COLDER AIR DOES NOT SURGE IN UNTIL THE BULK OF THE MOISTURE AND LIFT WITH THE STORM IS NE OF OUR AREA. THUS...IT LOOKS LIKE A RAIN EVENT...POSSIBLY MIXED WITH SLEET/SNOW FINGER LAKES/UPR MOHAWK/TUG HILL TUE EVE...THEN WRAP AROUND SNOW AND SNOW SHOWERS ENHANCED BY MOISTURE FROM LAKE ONTARIO TUE NGT/ERLY WED. THE SNOW SHOWERS WILL CONT WED IN C NY AS THE WRAP AROUND SNOW SHOWERS TRANSITIONS TO LAKE EFFECT SNOWS. THE INVERSION RAPIDLY DROPS DOWN TO 900 MB BY 00Z THU. THUS THERE WILL BE SOME LES...BUT IT SHUD NOT BE A MAJOR EVENT. MOST OF THE SNOW WILL FALL WED AM...IN NC NY WITH THE COMBINATION OF LAKE EFFECT AND SYNOPTIC MOISTURE. SEE 2-5 INCHES OF SNOW IN NC NY...WITH AN INCH OR LESS SC NY/FAR NRN PA AND LITTLE IF ANY IN THE REST OF NE PA. ANOTHER CONCERN IS THE POTENTIAL FOR HIGH WINDS ON WEDNESDAY AS THE DEEPENING CYCLONE DEPARTS ACRS LWR QUEBEC. MOS GUIDC SUGGESTS LOW END WIND ADVY CRITERIA. ISALLABORIC PRESSURE RISES ARE RUNNING CLOSE TO 10 MB/6 HR WHICH IS ALSO BORDERLINE FOR WIND ADVY. SO WILL HIGHLIGHT IN HWO FOR ENTIRE CWA...AND WILL HIGH POTENTIAL FOR SOME SNOW IN NC NY AS WELL. BY WED NGT...LES SNOW SHOWERS AND FLURRIES RAPIDLY COME TO AN END AS THE LL FLO TURNS MORE WRLY IN ADVANCE OF THE NEXT SYSTEM. && .LONG TERM /THURSDAY THROUGH MONDAY/... THE LONG TERM WILL BE DOMINATED BY A BRISK WEST TO EAST FLOW, AS THE STRONGLY POSITIVE PNA PATTERN RELAXES. THE RESULT WILL BE A SERIES OF CLIPPERS AND FAST MOVING SYSTEMS TRAVERSING THE GREAT LAKES AND SOUTHERN ONTARIO PROVINCE. HOWEVER BY LATE IN THE PERIOD, A JET WILL DIVE INTO THE PLAINS AND CARVE OUT ANOTHER DEEP TROUGH OVER THE WEST-CENTRAL UNITED STATES. THIS WILL CAUSE THE POSITIVE PNA PATTERN TO BEGIN TO STRENGTHEN AGAIN, WITH RISING HEIGHTS INTO THE EASTERN CONUS. AS A RESULT, WE ARE FORECASTING LOW POP, BRIEF DURATION RW/SW EVENTS WITH LITTLE ACCUMULATION ANTICIPATED. WE ARE ALSO FORECASTING TEMPERATURES SLIGHTLY ABOVE NORMAL FOR THE THURSDAY TO MONDAY PERIOD. && .AVIATION /03Z TUESDAY THROUGH SATURDAY/... CLOUDS HAVE MOVED EASTWARD, AWAY FROM THE TERMINALS LEAVING VFR CONDITIONS UNDER MOSTLY CLEAR SKIES. IT WILL BE A QUIET OVERNIGHT WITH LIGHT WINDS AND CIRRUS OVERHEAD. MVFR TO BORDER LINE IFR CONDITIONS WILL ARRIVE WITH RAIN ON TUESDAY AFTERNOON. THE RAIN MAKE IT TO THE AVP AND ELM TERMINALS BETWEEN 16Z AND 18Z, THEN SPREAD NORTHEAST TOWARD SYR AND RME BETWEEN 19Z AND 21Z. .OUTLOOK... TUE NGT/WED MORN...MVFR IN RAIN DROPPING TO IFR IN SNOW SHOWERS TUESDAY NIGHT. WED AFTN/THU...VFR. FRI/SAT...MAINLY VFR. POSSIBLE MVFR IN BRIEF SNOW SHOWERS. && .BGM WATCHES/WARNINGS/ADVISORIES... PA...NONE. NY...NONE. && $$ SYNOPSIS...SLI NEAR TERM...DJN/SLI SHORT TERM...DJN LONG TERM...DJP AVIATION...DJP
AREA FORECAST DISCUSSION
NWS BUFFALO NY
740 PM EST MON DEC 26 2011 .SYNOPSIS... HIGH PRESSURE CENTERED OVER VIRGINIA THIS EVENING WILL DRIFT OFF THE MID ATLANTIC COAST OVERNIGHT. A COMPLEX DOUBLE BARRELLED STORM SYSTEM STRETCHING FROM THE UPPER GREAT LAKES TO THE TENNESSEE VALLEY WILL THEN DEVELOP A CONSOLIDATED AREA OF LOW PRESSURE OVER PENNSYLVANIA LATE TUESDAY. THIS STORM SYSTEM IS FORECAST TO LIFT TO THE SAINT LAWRENCE VALLEY BY WEDNESDAY MORNING. THIS SCENARIO WILL LEAD TO RAIN AND MIXED PRECIPITATION ACROSS OUR REGION ON TUESDAY... WITH COLDER AIR ON THE BACKSIDE OF THE STORM CHANGING ALL OF THE PRECIPITATION TO ACCUMULATING SNOW LATE TUESDAY AND TUESDAY NIGHT. && .NEAR TERM /THROUGH TUESDAY/... IT WILL BE A VERY PLEASANT EARLY WINTER EVENING ACROSS THE FORECAST AREA AS SFC HIGH PRESSURE NOSING NORTH FROM VIRGINIA RESULTS IN CLEAR TO PARTLY CLOUDY SKIES. THIS SHOULD ALLOW FOR DECENT VIEWING OF VENUS IN THE SOUTHWESTERN SKY AND JUPITER TO THE SOUTHEAST. SKIES WILL BECOME INCREASINGLY CLOUDY DURING THE OVERNIGHT THOUGH...AS CIRRUS WILL STREAM NORTHWARDS AHEAD OF A PHASING SPLIT UPPER LEVEL FLOW. THE LATEST WATER IMAGERY SHOWS TWO DISTINCT SHORTWAVES. THE FIRST SHORT WAVE EMBEDDED WITHIN THE NORTHERN BRANCH OF THE JET STREAM WAS LOCATED OVER THE UPPER MISSISSIPPI VALLEY WHILE THE SOUTHERN BRANCH VORT CENTER WAS LOCATED OVER NORTH CENTRAL TEXAS. THE DEVELOPING SOUTHERLY FLOW BETWEEN THESE UPPER LEVEL IMPULSES AND THE EXITING HIGH PRESSURE WILL CIRCULATE INCREASED MOISTURE NORTHWARDS...WHILE ALSO DEVELOPING A WARM ADVECTIVE PATTERN. THIS SCENARIO WILL ALSO HELP TO HOLD UP OUR TEMPERATURES OVERNIGHT...SO THAT INSTEAD OF DROPPING TO OUR LATE AFTERNOON DEW POINT TEMPS (LOW-MID 20S)...MOST AREAS WILL ONLY BOTTOM OUT IN THE UPPER 20S TO LOWER 30S. SITES EAST OF LK ONTARIO WILL BE A BIT COLDER. THESE READINGS WILL BE SOME 10 DEG F ABOVE SEASONAL NORMALS. THE VORT MAXES WILL CONVERGE ON THE UPPER OHIO VALLEY TUESDAY WHILE LOW PRESSURE CONSOLIDATES IN THE VCNTY OF EASTERN OHIO AND WESTERN PENNSYLVANIA. WHILE THIS WILL INITIALLY KEEP A SOUTHERLY WARM ADVECTIVE FLOW OVER ALL OF OUR FORECAST AREA...THE MID LEVEL WARMTH WILL GET CUT OFF DURING THE COURSE OF THE AFTERNOON AS THE CIRCULATION ALOFT (THROUGH 10K FT) IS FORECAST TO CUT OFF OVER THE WRN COUNTIES. THIS WILL COMPLICATE AN ALREADY TRICKY FORECAST. THE DYNAMICS IMPOSED BY A DIVERGENT UPPER LEVEL FLOW AND RR QUAD OF A 130KT H25 JET WILL PROMOTE WIDESPREAD PCPN ACROSS OUR AREA ON TUESDAY...WITH THE PRECIPITATION LIFTING NORTHEAST AND SPREADING ACROSS THE WESTERN COUNTIES DURING THE MORNING AND MIDDAY. AREAS EAST OF LK ONTARIO SHOULD BE PCPN FREE UNTIL EARLY TO MID AFTERNOON. WHILE SFC TEMPS WILL RANGE FROM THE UPPER 30S TO LOWER 40S ACROSS MOST OF WESTERN NEW YORK AT THE ONSET OF THE PCPN...THERMAL PROFILES FROM BOTH THE NAM AND GFS SUGGEST THAT THE COLUMN WILL BE LARGELY BELOW FREEZING ABOVE 1500 FT. NOT ONLY IS THE BULK OF THE SOUNDING FORECAST TO BE BELOW FREEZING...BUT THE LOWEST 5K FT WILL LIKELY BE ISOTHERMAL BETWEEN MINUS 2 AND MINUS 5C. MORE ON THAT IN A MOMENT. THIS SOMEWHAT UNUSUAL SOUNDING IS DUE TO A RATHER STRANGE SFC STORM TRACK...THAT TAKES THE SFC LOW FROM NEAR PIT TO ABOUT BGM THEN TO BTV. SFC STORMS USUALLY TRACK WEST OR EAST OF THE OROGRAPHIC (ALLEGANY MTNS)...BUT IN THIS CASE THE LOW IS FORECAST TO TRACK ACROSS THE TOPOGRAPHY. AS MENTIONED EARLIER...THIS WILL CUT OFF THE MID LEVEL WARMTH FAIRLY EARLY ON IN THE EVENT SO HAVE LEANED TOWARDS A `COLDER` FORECAST WITH A FASTER CHANGEOVER TO MIXED/SNOW EVENT. FOR WHAT ITS WORTH...THE SREF PCPN PLUMES FAVOR THIS SOLUTION AND ARE IN FAIRLY GOOD AGREEMENT WITH THE FORECAST SOUNDINGS FROM THE OTHER MAJOR GUIDANCE PACKAGES. QPF FOR TUESDAY WILL RANGE FROM A QUARTER INCH ACROSS THE SRN TIER TO A LITTLE MORE THAN A TENTH ELSEWHERE. THIS IS NOT SIGNIFICANT FOR THE DAYLIGHT HOURS...ALTHOUGH THE HIGHER TERRAIN OF THE SOUTHERN TIER COULD PICK UP A WET INCH OR SO OF ACCUMULATION BY NIGHTFALL. ONE WORRISOME SUBTLETY IN THE FORECAST SOUNDINGS IS THAT A FAIRLY DEEP MINUS 2 TO MINUS 5 LAYER ISOTHERMAL LAYER WILL PROMOTE MORE EFFICIENT SNOW MAKING AS AGGREGATION IN THE LOW LEVELS COULD BE SIGNIFICANT. && .SHORT TERM /TUESDAY NIGHT THROUGH WEDNESDAY/... DEEPENING LOW PRESSURE TRACKING ACROSS NEW ENGLAND WILL BRING IN COLDER AIR TUESDAY NIGHT...WHICH WILL CHANGE PRECIPITATION OVER TO SNOW. THIS WILL LIKELY BRING ACCUMULATING SNOW TO ALL OF WESTERN NEW YORK...WITH THE POSSIBILITY OF MORE SIGNIFICANT (6 INCHES OR GREATER OF SNOW) ACROSS THE SOUTHERN TIER...AND EAST OF LAKE ONTARIO. MUCH COLDER AIR WILL MOVE IN WEDNESDAY...WITH LINGERING LAKE EFFECT SNOW SHOWERS SE OF LAKE ONTARIO...AND BLUSTERY CONDITIONS DURING THE DAY...WITH WITH HIGHS ON WEDNESDAY ONLY IN THE LOWER 20S ACROSS MUCH OF THE REGION. FOR THE DETAILS...MODEL AGREEMENT HAS IMPROVED WITH THE 12Z RUNS...WITH GENERALLY A FAIRLY TIGHT CLUSTER OF SOLUTIONS AMONG THE MODELS CONSULTED. THE BIGGEST MATERIAL DIFFERENCE AMONG MODELS IS HOW QUICKLY THE LOW DEEPENS...WITH THE 12Z NAM TRENDING SLOWER THAN MOST OTHER MODELS. USING A CONSENSUS OF THE 12Z RUNS OF THE NAM/RGEM/GFS/UKMET/EUROPEAN/SREF PUTTING 985 MB SURFACE LOW ALONG THE MAINE/QUEBEC BORDER AT 12Z WEDNESDAY. DESPITE THE FAIRLY GOOD MODEL AGREEMENT...THE CHALLENGE IN THIS EVENT IS THE DETAILS. BUT TUESDAY NIGHT...FORECAST SOUNDINGS WILL BE MARGINAL FOR SNOW IN FAR WESTERN SECTIONS...AND IN JEFFERSON/LEWIS COUNTIES. RAIN/SNOW WILL DEPEND ON SUBTLE DIFFERENCES IN SURFACE TEMPERATURE...WHERE HIGHER ELEVATIONS WILL LIKELY CHANGEOVER FIRST. LATE TUESDAY NIGHT...A STRONG PSEUDO-ARCTIC BOUNDARY WILL SWEEP ACROSS AS THE LOW INTENSIFIES IN EASTERN QUEBEC. COLD AIR WITH THIS WILL DEFINITELY CHANGE PRECIPITATION OVER TO SNOW...AND IT IS THIS FEATURE WHICH WILL LIKELY BRING AN INCH OR TWO ACROSS THE REGION. ON WEDNESDAY...THIS ARCTIC BOUNDARY WILL CONTINUE TO PUSH TO THE EAST OF REGION...USHERING IN COLD DAYTIME TEMPS. WITH THE UPPER TROF STILL BACK ACROSS THE REGION...EXPECT THIS WILL SET UP A BRIEF PERIOD OF LAKE ENHANCED SNOW SE OF LAKE ONTARIO...WAYNE COUNTY EASTWARD. WINDS WILL BE A BIT ON THE STRONG SIDE...BUT WITH RAPID COOLING...LAKE INDUCED INSTABILITY WILL INCREASE TO AROUND 300 J/KG. AS THE SHORTWAVE EXITS...THIS SHOULD DRY THE AIR OUT...ALLOWING LAKE SNOWS TO TAPER OFF. A WINTER STORM WATCH WAS CONSIDERED...BUT ULTIMATELY CONFIDENCE IS NOT QUITE HIGH ENOUGH FOR THE HEADLINE. SNOW AMOUNTS ARE MARGINAL TO SUPPORT THE HEADLINE...AND WITH THE SEVERAL CLOSE CALLS WITH THIS SYSTEM...FROM THE MARGINALLY COLD AIR MASS AT THE ONSET...TO THE FRONTAL BOUNDARY SNOW SHOWERS...TO THE POSSIBLE LAKE ENHANCEMENT AT THE END. BECAUSE OF THIS...WILL HOLD OFF ON ANY HEADLINES AND CONTINUE A MENTION IN THE HWO. FOR THOSE INTERESTED IN SNOW AMOUNTS...EXPECT MOST LOCATIONS TO BE IN THE 1 TO 3 INCH RANGE. THE EXCEPTIONS ARE WESTERN PORTIONS OF THE SOUTHERN TIER...AND E-SE OF LAKE ONTARIO...ROUGHLY INCLUDING WAYNE/N CAYUGA/OSWEGO/JEFFERSON/LEWIS COUNTIES...WHERE 4 INCHES OR GREATER OF SNOW ARE LIKELY. DEPENDING ON HOW SEVERAL FACTORS WORK OUT...COULD SEE AMOUNTS TO 8 INCHES IN SOME OF THESE LOCATIONS...HOWEVER AMOUNTS THIS HIGH ARE ONLY A POSSIBILITY AT THIS TIME. THERE WILL BE OTHER IMPACTS WITH THIS SYSTEM. THE FRONTAL BOUNDARY WILL CAUSE TEMPERATURES TO DROP QUITE RAPIDLY EARLY WEDNESDAY MORNING. THIS MAY CAUSE ANY WATER OR SLUSH ON ROADWAYS TO FREEZE...POTENTIALLY MAKING FOR A SLICK COMMUTE WEDNESDAY MORNING. ALSO...THE TIMING OF THE FRONTAL BOUNDARY WILL BE KEY...AS EVEN AN INCH OR TWO OF SNOW CAN BE A NUISANCE...IF IT COMES QUICKLY AND NEAR RUSH HOUR. && .LONG TERM /WEDNESDAY NIGHT THROUGH MONDAY/... HIGH PRESSURE WILL BRIEFLY RIDGE ACROSS THE REGION WEDNESDAY NIGHT. THERE MAY BE SOME LINGERING LAKE EFFECT SNOW SHOWERS EAST OF LAKE ONTARIO...WITH THIS TO END AS WINDS SHIFT TO THE SW LATE IN THE NIGHT. THE THURSDAY THROUGH SUNDAY PERIOD WILL FEATURE A ZONAL FLOW...WITH A COUPLE OF CLIPPERS FORECAST TO CROSS THE REGION. THE 12Z GFS/EUROPEAN/GGEM DIFFER ON THE TIMING OF THESE FAST SYSTEM...MAKING POPS DIFFICULT TO BE TOO SPECIFIC. ALSO...TEMPERATURES WILL BE MARGINAL FOR LAKE EFFECT AHEAD OF THE CLIPPER. THE RESULT WILL BE ONLY MODEST LEVELS OF INSTABILITY...AND TEMPERATURES WILL AT TIMES BE MARGINALLY COLD ENOUGH FOR SNOW...WITH SOME RAIN POSSIBLE. GIVEN THE MARGINALLY COLD 850MB TEMPS...DO NOT EXPECT ANY MAJOR EVENTS FROM THESE CLIPPERS...BUT IT WILL BE HARD TO RULE OUT A RAIN OR SNOW SHOWER DURING THIS PERIOD...EVEN IF THE MAJORITY OF THE TIME WILL BE DRY. A STALLED FRONTAL BOUNDARY WILL BE CLOSE TO THE EASTERN LAKE ONTARIO REGION...SO AS THIS FLUCTUATES WITH THE SYSTEMS...IT MAY BE MARKEDLY COLDER THERE AT TIMES. ON MONDAY...THE EUROPEAN LIFTS LOW PRESSURE ACROSS THE REGION...WITH THE GFS/GGEM SHOWING MORE OF A RIDGE. NO STRONG FEELINGS EITHER WAY ON THIS...AND WILL SIMPLY MAINTAIN CHANCE POPS. && .AVIATION /01Z TUESDAY THROUGH SATURDAY/... VFR CONDITIONS WILL BE IN PLACE TONIGHT THROUGH AT LEAST THE FIRST HALF OF TUESDAY...DESPITE AN INCREASE IN HIGH AND MID LEVEL MOISTURE. THE INCREASED CLOUD COVER WILL BE DUE A DEVELOPING AREA OF LOW PRESSURE OVER THE UPPER OHIO VALLEY. CLOUDS FROM THE APPROACHING LOW WILL LOWER AND THICKEN ON TUESDAY...WITH RAIN (MIXED PCPN HIGHER ELEVATIONS) LIFTING FROM THE SOUTHWEST CORNER OF THE STATE TO THE EASTERN LAKE ONTARIO REGION. THE LATEST NAM12 GUIDANCE SUGGESTS THAT THE COLDER AIR MAY ARRIVE A LITTLE SOONER. BASED ON THIS TREND...HAVE DECIDED TO SHOW MORE A RAIN/SNOW MIX AT MOST TAF SITES TOWARD LATE AFTERNOON. CIGS BY LATE AFTERNOON WILL RANGE FROM IFR ACROSS THE WESTERN COUNTIES TO MVFR NEAR KART AND KGTB. MARGINAL LLWS IS ALSO POSSIBLE TONIGHT AS A LOW LEVEL JET TRACKS JUST NORTH OF NEW YORK STATE...GENERALLY BETWEEN 06Z-12Z. OUTLOOK... TUESDAY NIGHT...IFR WITH WIDESPREAD RAIN CHANGING TO WET SNOW. WEDNESDAY...MVFR WITH MORNING SNOW SHOWERS IMPROVING TO VFR. THURSDAY...MAINLY VFR. THURSDAY NIGHT AND FRIDAY...MVFR WITH A CHANCE OF RAIN AND SNOW SHOWERS. SATURDAY...VFR. && .MARINE... THE SOUTHERLY FLOW ACROSS THE LOWER LAKES HAS WEAKENED CONSIDERABLY THIS EVENING...BUT WILL PICK UP A LITTLE MORE OVERNIGHT AS A LOW LEVEL JET TRACKS JUST NORTH OF NEW YORK STATE. STILL LOOKS LIKE THE HIGHER WAVES WILL MAINLY IMPACT THE OPEN WATERS OF THE LAKES...AND THE FAR EASTERN NEAR SHORES OF LAKE ONTARIO. A STORM SYSTEM WILL DEVELOP OVER THE MID WEST ON TUESDAY AND APPROACH THE LOWER GREAT LAKES DURING THE AFTERNOON AND EVENING. THIS WILL ACTUALLY WEAKEN THE SFC PRESSURE GRADIENT IN THIS CASE SO THAT WINDS AND WAVES SHOULD BE BELOW SCA CRITERIA. AS THE SYSTEM MOVES TO THE SAINT LAWRENCE VALLEY AND STRENGTHENS TUESDAY NIGHT...STRONG NORTHWEST WINDS WILL DEVELOP ACROSS LAKE ERIE...AND BY DAYBREAK WEDNESDAY...ACROSS LAKE ONTARIO. DEFINITE SCA CONDITIONS WILL BE IN PLACE AT THAT TIME...WITH THE THREAT OF GALE FORCE WINDS. && .BUF WATCHES/WARNINGS/ADVISORIES... NY...NONE. MARINE...SMALL CRAFT ADVISORY UNTIL 4 AM EST TUESDAY FOR LOZ045. && $$ SYNOPSIS...RSH NEAR TERM...RSH/TJP SHORT TERM...APFFEL LONG TERM...APFFEL AVIATION...RSH/TJP MARINE...RSH/TJP
AREA FORECAST DISCUSSION
NWS BUFFALO NY
722 PM EST MON DEC 26 2011 .SYNOPSIS... HIGH PRESSURE CENTERED OVER VIRGINIA THIS EVENING WILL DRIFT OFF THE MID ATLANTIC COAST OVERNIGHT. A COMPLEX DOUBLE BARRELLED STORM SYSTEM STRETCHING FROM THE UPPER GREAT LAKES TO THE TENNESSEE VALLEY WILL THEN DEVELOP A CONSOLIDATED AREA OF LOW PRESSURE OVER PENNSYLVANIA LATE TUESDAY. THIS STORM SYSTEM IS FORECAST TO LIFT TO THE SAINT LAWRENCE VALLEY BY WEDNESDAY MORNING. THIS SCENARIO WILL LEAD TO RAIN AND MIXED PRECIPITATION ACROSS OUR REGION ON TUESDAY... WITH COLDER AIR ON THE BACKSIDE OF THE STORM CHANGING ALL OF THE PRECIPITATION TO ACCUMULATING SNOW LATE TUESDAY AND TUESDAY NIGHT. && .NEAR TERM /THROUGH TUESDAY/... IT WILL BE A VERY PLEASANT EARLY WINTER EVENING ACROSS THE FORECAST AREA AS SFC HIGH PRESSURE NOSING NORTH FROM VIRGINIA RESULTS IN CLEAR TO PARTLY CLOUDY SKIES. THIS SHOULD ALLOW FOR DECENT VIEWING OF VENUS IN THE SOUTHWESTERN SKY AND JUPITER TO THE SOUTHEAST. SKIES WILL BECOME INCREASINGLY CLOUDY DURING THE OVERNIGHT THOUGH...AS CIRRUS WILL STREAM NORTHWARDS AHEAD OF A PHASING SPLIT UPPER LEVEL FLOW. THE LATEST WATER IMAGERY SHOWS TWO DISTINCT SHORTWAVES. THE FIRST SHORT WAVE EMBEDDED WITHIN THE NORTHERN BRANCH OF THE JET STREAM WAS LOCATED OVER THE UPPER MISSISSIPPI VALLEY WHILE THE SOUTHERN BRANCH VORT CENTER WAS LOCATED OVER NORTH CENTRAL TEXAS. THE DEVELOPING SOUTHERLY FLOW BETWEEN THESE UPPER LEVEL IMPULSES AND THE EXITING HIGH PRESSURE WILL CIRCULATE INCREASED MOISTURE NORTHWARDS...WHILE ALSO DEVELOPING A WARM ADVECTIVE PATTERN. THIS SCENARIO WILL ALSO HELP TO HOLD UP OUR TEMPERATURES OVERNIGHT...SO THAT INSTEAD OF DROPPING TO OUR LATE AFTERNOON DEW POINT TEMPS (LOW-MID 20S)...MOST AREAS WILL ONLY BOTTOM OUT IN THE UPPER 20S TO LOWER 30S. SITES EAST OF LK ONTARIO WILL BE A BIT COLDER. THESE READINGS WILL BE SOME 10 DEG F ABOVE SEASONAL NORMALS. THE VORT MAXES WILL CONVERGE ON THE UPPER OHIO VALLEY TUESDAY WHILE LOW PRESSURE CONSOLIDATES IN THE VCNTY OF EASTERN OHIO AND WESTERN PENNSYLVANIA. WHILE THIS WILL INITIALLY KEEP A SOUTHERLY WARM ADVECTIVE FLOW OVER ALL OF OUR FORECAST AREA...THE MID LEVEL WARMTH WILL GET CUT OFF DURING THE COURSE OF THE AFTERNOON AS THE CIRCULATION ALOFT (THROUGH 10K FT) IS FORECAST TO CUT OFF OVER THE WRN COUNTIES. THIS WILL COMPLICATE AN ALREADY TRICKY FORECAST. THE DYNAMICS IMPOSED BY A DIVERGENT UPPER LEVEL FLOW AND RR QUAD OF A 130KT H25 JET WILL PROMOTE WIDESPREAD PCPN ACROSS OUR AREA ON TUESDAY...WITH THE PRECIPITATION LIFTING NORTHEAST AND SPREADING ACROSS THE WESTERN COUNTIES DURING THE MORNING AND MIDDAY. AREAS EAST OF LK ONTARIO SHOULD BE PCPN FREE UNTIL EARLY TO MID AFTERNOON. WHILE SFC TEMPS WILL RANGE FROM THE UPPER 30S TO LOWER 40S ACROSS MOST OF WESTERN NEW YORK AT THE ONSET OF THE PCPN...THERMAL PROFILES FROM BOTH THE NAM AND GFS SUGGEST THAT THE COLUMN WILL BE LARGELY BELOW FREEZING ABOVE 1500 FT. NOT ONLY IS THE BULK OF THE SOUNDING FORECAST TO BE BELOW FREEZING...BUT THE LOWEST 5K FT WILL LIKELY BE ISOTHERMAL BETWEEN MINUS 2 AND MINUS 5C. MORE ON THAT IN A MOMENT. THIS SOMEWHAT UNUSUAL SOUNDING IS DUE TO A RATHER STRANGE SFC STORM TRACK...THAT TAKES THE SFC LOW FROM NEAR PIT TO ABOUT BGM THEN TO BTV. SFC STORMS USUALLY TRACK WEST OR EAST OF THE OROGRAPHIC (ALLEGANY MTNS)...BUT IN THIS CASE THE LOW IS FORECAST TO TRACK ACROSS THE TOPOGRAPHY. AS MENTIONED EARLIER...THIS WILL CUT OFF THE MID LEVEL WARMTH FAIRLY EARLY ON IN THE EVENT SO HAVE LEANED TOWARDS A `COLDER` FORECAST WITH A FASTER CHANGEOVER TO MIXED/SNOW EVENT. FOR WHAT ITS WORTH...THE SREF PCPN PLUMES FAVOR THIS SOLUTION AND ARE IN FAIRLY GOOD AGREEMENT WITH THE FORECAST SOUNDINGS FROM THE OTHER MAJOR GUIDANCE PACKAGES. QPF FOR TUESDAY WILL RANGE FROM A QUARTER INCH ACROSS THE SRN TIER TO A LITTLE MORE THAN A TENTH ELSEWHERE. THIS IS NOT SIGNIFICANT FOR THE DAYLIGHT HOURS...ALTHOUGH THE HIGHER TERRAIN OF THE SOUTHERN TIER COULD PICK UP A WET INCH OR SO OF ACCUMULATION BY NIGHTFALL. ONE WORRISOME SUBTLETY IN THE FORECAST SOUNDINGS IS THAT A FAIRLY DEEP MINUS 2 TO MINUS 5 LAYER ISOTHERMAL LAYER WILL PROMOTE MORE EFFICIENT SNOW MAKING AS AGGREGATION IN THE LOW LEVELS COULD BE SIGNIFICANT. && .SHORT TERM /TUESDAY NIGHT THROUGH WEDNESDAY/... DEEPENING LOW PRESSURE TRACKING ACROSS NEW ENGLAND WILL BRING IN COLDER AIR TUESDAY NIGHT...WHICH WILL CHANGE PRECIPITATION OVER TO SNOW. THIS WILL LIKELY BRING ACCUMULATING SNOW TO ALL OF WESTERN NEW YORK...WITH THE POSSIBILITY OF MORE SIGNIFICANT (6 INCHES OR GREATER OF SNOW) ACROSS THE SOUTHERN TIER...AND EAST OF LAKE ONTARIO. MUCH COLDER AIR WILL MOVE IN WEDNESDAY...WITH LINGERING LAKE EFFECT SNOW SHOWERS SE OF LAKE ONTARIO...AND BLUSTERY CONDITIONS DURING THE DAY...WITH WITH HIGHS ON WEDNESDAY ONLY IN THE LOWER 20S ACROSS MUCH OF THE REGION. FOR THE DETAILS...MODEL AGREEMENT HAS IMPROVED WITH THE 12Z RUNS...WITH GENERALLY A FAIRLY TIGHT CLUSTER OF SOLUTIONS AMONG THE MODELS CONSULTED. THE BIGGEST MATERIAL DIFFERENCE AMONG MODELS IS HOW QUICKLY THE LOW DEEPENS...WITH THE 12Z NAM TRENDING SLOWER THAN MOST OTHER MODELS. USING A CONSENSUS OF THE 12Z RUNS OF THE NAM/RGEM/GFS/UKMET/EUROPEAN/SREF PUTTING 985 MB SURFACE LOW ALONG THE MAINE/QUEBEC BORDER AT 12Z WEDNESDAY. DESPITE THE FAIRLY GOOD MODEL AGREEMENT...THE CHALLENGE IN THIS EVENT IS THE DETAILS. BUT TUESDAY NIGHT...FORECAST SOUNDINGS WILL BE MARGINAL FOR SNOW IN FAR WESTERN SECTIONS...AND IN JEFFERSON/LEWIS COUNTIES. RAIN/SNOW WILL DEPEND ON SUBTLE DIFFERENCES IN SURFACE TEMPERATURE...WHERE HIGHER ELEVATIONS WILL LIKELY CHANGEOVER FIRST. LATE TUESDAY NIGHT...A STRONG PSEUDO-ARCTIC BOUNDARY WILL SWEEP ACROSS AS THE LOW INTENSIFIES IN EASTERN QUEBEC. COLD AIR WITH THIS WILL DEFINITELY CHANGE PRECIPITATION OVER TO SNOW...AND IT IS THIS FEATURE WHICH WILL LIKELY BRING AN INCH OR TWO ACROSS THE REGION. ON WEDNESDAY...THIS ARCTIC BOUNDARY WILL CONTINUE TO PUSH TO THE EAST OF REGION...USHERING IN COLD DAYTIME TEMPS. WITH THE UPPER TROF STILL BACK ACROSS THE REGION...EXPECT THIS WILL SET UP A BRIEF PERIOD OF LAKE ENHANCED SNOW SE OF LAKE ONTARIO...WAYNE COUNTY EASTWARD. WINDS WILL BE A BIT ON THE STRONG SIDE...BUT WITH RAPID COOLING...LAKE INDUCED INSTABILITY WILL INCREASE TO AROUND 300 J/KG. AS THE SHORTWAVE EXITS...THIS SHOULD DRY THE AIR OUT...ALLOWING LAKE SNOWS TO TAPER OFF. A WINTER STORM WATCH WAS CONSIDERED...BUT ULTIMATELY CONFIDENCE IS NOT QUITE HIGH ENOUGH FOR THE HEADLINE. SNOW AMOUNTS ARE MARGINAL TO SUPPORT THE HEADLINE...AND WITH THE SEVERAL CLOSE CALLS WITH THIS SYSTEM...FROM THE MARGINALLY COLD AIR MASS AT THE ONSET...TO THE FRONTAL BOUNDARY SNOW SHOWERS...TO THE POSSIBLE LAKE ENHANCEMENT AT THE END. BECAUSE OF THIS...WILL HOLD OFF ON ANY HEADLINES AND CONTINUE A MENTION IN THE HWO. FOR THOSE INTERESTED IN SNOW AMOUNTS...EXPECT MOST LOCATIONS TO BE IN THE 1 TO 3 INCH RANGE. THE EXCEPTIONS ARE WESTERN PORTIONS OF THE SOUTHERN TIER...AND E-SE OF LAKE ONTARIO...ROUGHLY INCLUDING WAYNE/N CAYUGA/OSWEGO/JEFFERSON/LEWIS COUNTIES...WHERE 4 INCHES OR GREATER OF SNOW ARE LIKELY. DEPENDING ON HOW SEVERAL FACTORS WORK OUT...COULD SEE AMOUNTS TO 8 INCHES IN SOME OF THESE LOCATIONS...HOWEVER AMOUNTS THIS HIGH ARE ONLY A POSSIBILITY AT THIS TIME. THERE WILL BE OTHER IMPACTS WITH THIS SYSTEM. THE FRONTAL BOUNDARY WILL CAUSE TEMPERATURES TO DROP QUITE RAPIDLY EARLY WEDNESDAY MORNING. THIS MAY CAUSE ANY WATER OR SLUSH ON ROADWAYS TO FREEZE...POTENTIALLY MAKING FOR A SLICK COMMUTE WEDNESDAY MORNING. ALSO...THE TIMING OF THE FRONTAL BOUNDARY WILL BE KEY...AS EVEN AN INCH OR TWO OF SNOW CAN BE A NUISANCE...IF IT COMES QUICKLY AND NEAR RUSH HOUR. && .LONG TERM /WEDNESDAY NIGHT THROUGH MONDAY/... HIGH PRESSURE WILL BRIEFLY RIDGE ACROSS THE REGION WEDNESDAY NIGHT. THERE MAY BE SOME LINGERING LAKE EFFECT SNOW SHOWERS EAST OF LAKE ONTARIO...WITH THIS TO END AS WINDS SHIFT TO THE SW LATE IN THE NIGHT. THE THURSDAY THROUGH SUNDAY PERIOD WILL FEATURE A ZONAL FLOW...WITH A COUPLE OF CLIPPERS FORECAST TO CROSS THE REGION. THE 12Z GFS/EUROPEAN/GGEM DIFFER ON THE TIMING OF THESE FAST SYSTEM...MAKING POPS DIFFICULT TO BE TOO SPECIFIC. ALSO...TEMPERATURES WILL BE MARGINAL FOR LAKE EFFECT AHEAD OF THE CLIPPER. THE RESULT WILL BE ONLY MODEST LEVELS OF INSTABILITY...AND TEMPERATURES WILL AT TIMES BE MARGINALLY COLD ENOUGH FOR SNOW...WITH SOME RAIN POSSIBLE. GIVEN THE MARGINALLY COLD 850MB TEMPS...DO NOT EXPECT ANY MAJOR EVENTS FROM THESE CLIPPERS...BUT IT WILL BE HARD TO RULE OUT A RAIN OR SNOW SHOWER DURING THIS PERIOD...EVEN IF THE MAJORITY OF THE TIME WILL BE DRY. A STALLED FRONTAL BOUNDARY WILL BE CLOSE TO THE EASTERN LAKE ONTARIO REGION...SO AS THIS FLUCTUATES WITH THE SYSTEMS...IT MAY BE MARKEDLY COLDER THERE AT TIMES. ON MONDAY...THE EUROPEAN LIFTS LOW PRESSURE ACROSS THE REGION...WITH THE GFS/GGEM SHOWING MORE OF A RIDGE. NO STRONG FEELINGS EITHER WAY ON THIS...AND WILL SIMPLY MAINTAIN CHANCE POPS. && .AVIATION /01Z TUESDAY THROUGH SATURDAY/... VFR CONDITIONS WILL BE IN PLACE TONIGHT THROUGH AT LEAST THE FIRST HALF OF TUESDAY...DESPITE AN INCREASE IN HIGH AND MID LEVEL MOISTURE. THE INCREASED CLOUD COVER WILL BE DUE A DEVELOPING AREA OF LOW PRESSURE OVER THE UPPER OHIO VALLEY. CLOUDS FROM THE APPROACHING LOW WILL LOWER AND THICKEN ON TUESDAY...WITH RAIN (MIXED PCPN HIGHER ELEVATIONS) LIFTING FROM THE SOUTHWEST CORNER OF THE STATE TO THE EASTERN LAKE ONTARIO REGION. THE LATEST NAM12 GUIDANCE SUGGESTS THAT THE COLDER AIR MAY ARRIVE A LITTLE SOONER. BASED ON THIS TREND...HAVE DECIDED TO SHOW MORE A RAIN/SNOW MIX AT MOST TAF SITES TOWARD LATE AFTERNOON. CIGS BY LATE AFTERNOON WILL RANGE FROM IFR ACROSS THE WESTERN COUNTIES TO MVFR NEAR KART AND KGTB. MARGINAL LLWS IS ALSO POSSIBLE TONIGHT AS A LOW LEVEL JET TRACKS JUST NORTH OF NEW YORK STATE...GENERALLY BETWEEN 06Z-12Z. OUTLOOK... TUESDAY NIGHT...IFR WITH WIDESPREAD RAIN CHANGING TO WET SNOW. WEDNESDAY...MVFR WITH MORNING SNOW SHOWERS IMPROVING TO VFR. THURSDAY...MAINLY VFR. THURSDAY NIGHT AND FRIDAY...MVFR WITH A CHANCE OF RAIN AND SNOW SHOWERS. SATURDAY...VFR. && .MARINE... HIGH PRESSURE NOSING NORTH FROM VIRGINIA WILL KEEP MODERATE TO FRESH SOUTHWESTERLIES ACROSS LAKE ERIE AND EASTERN LAKE ONTARIO THROUGH THIS EVENING SO SMALL CRAFT ADVISORIES WILL REMAIN IN EFFECT FOR THOSE NEARSHORE WATERS. AS THE NIGHT PROGRESSES...THE FLOW WILL BACK TO THE SOUTH AND WEAKEN. THIS WILL ALLOW WAVES TO SUBSIDE A BIT WHILE MORE IMPORTANTLY PUSHING THE HIGHEST WAVES TO CANADIAN WATERS. A STORM SYSTEM WILL DEVELOP OVER THE MID WEST ON TUESDAY AND APPROACH THE LOWER GREAT LAKES DURING THE AFTERNOON AND EVENING. THIS WILL ACTUALLY WEAKEN THE SFC PRESSURE GRADIENT IN THIS CASE SO THAT WINDS AND WAVES SHOULD BE BELOW SCA CRITERIA. AS THE SYSTEM MOVES TO THE SAINT LAWRENCE VALLEY AND STRENGTHENS TUESDAY NIGHT...STRONG NORTHWEST WINDS WILL DEVELOP ACROSS LAKE ERIE...AND BY DAYBREAK WEDNESDAY...ACROSS LAKE ONTARIO. DEFINITE SCA CONDITIONS WILL BE IN PLACE AT THAT TIME...WITH THE THREAT OF GALE FORCE WINDS. && .BUF WATCHES/WARNINGS/ADVISORIES... NY...NONE. MARINE...SMALL CRAFT ADVISORY UNTIL 10 PM EST THIS EVENING FOR LOZ043- 044. SMALL CRAFT ADVISORY UNTIL 4 AM EST TUESDAY FOR LOZ045. && $$ SYNOPSIS...RSH NEAR TERM...RSH/TJP SHORT TERM...APFFEL LONG TERM...APFFEL AVIATION...RSH/TJP MARINE...RSH
AREA FORECAST DISCUSSION
NWS BINGHAMTON NY
708 PM EST MON DEC 26 2011 .SYNOPSIS... SOUTHERLY FLOW AHEAD OF A LOW PRESSURE SYSTEM WILL BRING MILDER TEMPERATURES TO THE AREA TOMORROW. RAIN WILL MOVE INTO THE AREA TUESDAY AFTERNOON. THERE WILL BE A CHANGE OVER TO SNOW LATE TUESDAY NIGHT AS COLDER AIR MOVES BACK IN. LAKE EFFECT SNOW IS POSSIBLE ON WEDNESDAY. HIGH PRESSURE WILL BUILD IN THURSDAY. && .NEAR TERM /THROUGH TUESDAY/... VIS SATL IMAGERY SHOWS SC LAYER OVER ALL OF C NY AND NE PA. LARGE SCALE SUBSC BEHIND DEPARTING SHRT WAVE OFF THE NE COAST WILL CONT TO PUSH INVERSION DOWN AND EVENTUALLY WILL LEAD TO CLRG SKIES LATE THIS AFTERNOON AND ERLY EVENING. VIS SATL IMAGERY ALREADY SHOWG THIS IN WRN NY AND NC/NE PA. THE BACK EDGE OF THE SC LAYER CORRELATED WELL WITH THE 850 MB TEMP GRADIENT WHICH IS INDICATIVE OF THE SUBSC. USING THE LOCAL WRFARW...THIS GRADIENT MOVES THRU BTWN 21Z AND 00Z...WHILE THE RUC13 HOLDS ONTO THE COLDER H85 TEMPS IN EC NY A LITTLE LONGER. IN ANY EVENT BOTH SEEM TO SHOW SIGNS THAT THIS CLRG WILL TAKE A BIT LONGER IN EC NY...WHERE THERE IS HIGHER TERRAIN. THIS MAKES SENSE AND WILL HOLD ONTO CLDS A LITTLE LONGER IN THESE AREAS. REST OF AREA SEES CLRG FOR A TIME THIS EVENING. AFTER THE CLDS CLEAR OUT THIS EVENING...HIGHER CLDS FROM THE NEXT SYSTEM BEGIN TO SPREAD ACROSS NY AND PA. THE SFC RDG AXIS IS E OF THE REGION TONIGHT AS THE NEXT SYSTEM RAPIDLY APPRCHES FROM THE SRN PLAINS AND UPR MIDWEST. THE LL FLO WILL TURN SWRLY AND SHUD KEEP TEMPS FROM BOTTOMING OUT MUCH BELOW 30 MOST PLACES. THE EXCEPTION IS IN NE PA/SERN NY WHERE THE WINDS WILL REMAIN LIGHT ENUF WITH CLR SKIES. THUS MINS WILL BE HIGHER IN THE NW CWA LOW 30S AND LOWER IN THE SE CWA MID TO UPPER 20S OR SO. FOR TUESDAY...CLDS WILL INCREASE THRU THE DAY AS STRG WAA/ISEN LIFT TAKES PLACE THRU A DEEPER AND DEEPER LAYER AS THE DAY PROGRESSES. TEMPS FROM THE SFC THRU 850 MB WILL BE WARM ENUF FOR ALL RAIN ENTIRE CWA. ALL SYNOPTIC SCALE MODELS INDICATE THAT THE RAIN WILL MOVE IN DURING THE AFTERNOON. WILL RAMP POPS UP BTWN 18Z TUE AND 00Z WED. && .SHORT TERM /TUESDAY NIGHT THROUGH WEDNESDAY NIGHT/... THE 12Z EURO...18Z NAM...12Z GFS HAVE TRENDED MORE TOWARD THE WEST WITH THE SFC LO AND ALL INDICATE THAT THE 850 MB LOW TRACKS TO WRN NY BY 00Z WED. THIS WILL ALLOW 850 MB TEMPS TO CLIMB WELL ABV FRZG AS THE PRECIP WORKS IN. WITH BNDRY LAYER TEMPS EXPECTED ABV FRZG...PRECIP WILL BE MAINLY RAIN AT THE ONSET. IN ADDTN...WITH THIS MORE WRN TRACK...THE DRY SLOT WITH THE DEVELOPING CYCLONE MOVES RIGHT THRU NE PA AND C NY TUE EVE. COLDER AIR DOES NOT SURGE IN UNTIL THE BULK OF THE MOISTURE AND LIFT WITH THE STORM IS NE OF OUR AREA. THUS...IT LOOKS LIKE A RAIN EVENT...POSSIBLY MIXED WITH SLEET/SNOW FINGER LAKES/UPR MOHAWK/TUG HILL TUE EVE...THEN WRAP AROUND SNOW AND SNOW SHOWERS ENHANCED BY MOISTURE FROM LAKE ONTARIO TUE NGT/ERLY WED. THE SNOW SHOWERS WILL CONT WED IN C NY AS THE WRAP AROUND SNOW SHOWERS TRANSITIONS TO LAKE EFFECT SNOWS. THE INVERSION RAPIDLY DROPS DOWN TO 900 MB BY 00Z THU. THUS THERE WILL BE SOME LES...BUT IT SHUD NOT BE A MAJOR EVENT. MOST OF THE SNOW WILL FALL WED AM...IN NC NY WITH THE COMBINATION OF LAKE EFFECT AND SYNOPTIC MOISTURE. SEE 2-5 INCHES OF SNOW IN NC NY...WITH AN INCH OR LESS SC NY/FAR NRN PA AND LITTLE IF ANY IN THE REST OF NE PA. ANOTHER CONCERN IS THE POTENTIAL FOR HIGH WINDS ON WEDNESDAY AS THE DEEPENING CYCLONE DEPARTS ACRS LWR QUEBEC. MOS GUIDC SUGGESTS LOW END WIND ADVY CRITERIA. ISALLABORIC PRESSURE RISES ARE RUNNING CLOSE TO 10 MB/6 HR WHICH IS ALSO BORDERLINE FOR WIND ADVY. SO WILL HIGHLIGHT IN HWO FOR ENTIRE CWA...AND WILL HIGH POTENTIAL FOR SOME SNOW IN NC NY AS WELL. BY WED NGT...LES SNOW SHOWERS AND FLURRIES RAPIDLY COME TO AN END AS THE LL FLO TURNS MORE WRLY IN ADVANCE OF THE NEXT SYSTEM. && .LONG TERM /THURSDAY THROUGH MONDAY/... THE LONG TERM WILL BE DOMINATED BY A BRISK WEST TO EAST FLOW, AS THE STRONGLY POSITIVE PNA PATTERN RELAXES. THE RESULT WILL BE A SERIES OF CLIPPERS AND FAST MOVING SYSTEMS TRAVERSING THE GREAT LAKES AND SOUTHERN ONTARIO PROVINCE. HOWEVER BY LATE IN THE PERIOD, A JET WILL DIVE INTO THE PLAINS AND CARVE OUT ANOTHER DEEP TROUGH OVER THE WEST-CENTRAL UNITED STATES. THIS WILL CAUSE THE POSITIVE PNA PATTERN TO BEGIN TO STRENGTHEN AGAIN, WITH RISING HEIGHTS INTO THE EASTERN CONUS. AS A RESULT, WE ARE FORECASTING LOW POP, BRIEF DURATION RW/SW EVENTS WITH LITTLE ACCUMULATION ANTICIPATED. WE ARE ALSO FORECASTING TEMPERATURES SLIGHTLY ABOVE NORMAL FOR THE THURSDAY TO MONDAY PERIOD. && .AVIATION /00Z TUESDAY THROUGH SATURDAY/... CLOUDS HAVE MOVED EASTWARD, AWAY FROM THE TERMINALS LEAVING VFR CONDITIONS UNDER MOSTLY CLEAR SKIES. IT WILL BE A QUIET OVERNIGHT WITH LIGHT WINDS AND CIRRUS OVERHEAD. MVFR TO BORDER LINE IFR CONDITIONS WILL ARRIVE WITH RAIN ON TUESDAY AFTERNOON. THE RAIN MAKE IT TO THE AVP AND ELM TERMINALS BETWEEN 16Z AND 18Z, THEN SPREAD NORTHEAST TOWARD SYR AND RME BETWEEN 19Z AND 21Z. .OUTLOOK... TUE NGT/WED MORN...MVFR IN RAIN DROPPING TO IFR IN SNOW SHOWERS TUESDAY NIGHT. WED AFTN/THU...VFR. FRI/SAT...MAINLY VFR. POSSIBLE MVFR IN BRIEF SNOW SHOWERS. && .BGM WATCHES/WARNINGS/ADVISORIES... PA...NONE. NY...NONE. && $$ SYNOPSIS...SLI NEAR TERM...DJN SHORT TERM...DJN LONG TERM...DJP AVIATION...DJP
AREA FORECAST DISCUSSION
NWS BINGHAMTON NY
621 PM EST MON DEC 26 2011 .SYNOPSIS... A RIDGE OF HIGH PRESSURE WILL RAPIDLY MOVE OFF THE EAST COAST TONIGHT ALLOWING FOR A SOUTHERLY FLOW OF MILDER AIR TO DEVELOP OVER THE REGION LATER TONIGHT AND TUESDAY. WITH MILDER AIR IN PLACE...MAINLY RAIN WILL FALL ACROSS THE REGION TUESDAY AFTERNOON AND EVENING AS A STORM SYSTEM TRACKS NORTHEAST THROUGH PENNSYLVANIA AND NEW YORK. AFTER THIS STORM PASSES TO THE NORTHEAST TUESDAY NIGHT COLDER AIR WILL RETURN TO THE REGION CHANGING THE RAIN TO SNOW AND SNOW SHOWERS. MOST OF THE REGION WILL SEE LITTLE SNOW ACCUMULATION...EXCEPT FOR NORTH CENTRAL NEW YORK WHERE A FEW INCHES IS POSSIBLE BY WEDNESDAY AFTERNOON. && .NEAR TERM /THROUGH TUESDAY/... VIS SATL IMAGERY SHOWS SC LAYER OVER ALL OF C NY AND NE PA. LARGE SCALE SUBSC BEHIND DEPARTING SHRT WAVE OFF THE NE COAST WILL CONT TO PUSH INVERSION DOWN AND EVENTUALLY WILL LEAD TO CLRG SKIES LATE THIS AFTERNOON AND ERLY EVENING. VIS SATL IMAGERY ALREADY SHOWG THIS IN WRN NY AND NC/NE PA. THE BACK EDGE OF THE SC LAYER CORRELATED WELL WITH THE 850 MB TEMP GRADIENT WHICH IS INDICATIVE OF THE SUBSC. USING THE LOCAL WRFARW...THIS GRADIENT MOVES THRU BTWN 21Z AND 00Z...WHILE THE RUC13 HOLDS ONTO THE COLDER H85 TEMPS IN EC NY A LITTLE LONGER. IN ANY EVENT BOTH SEEM TO SHOW SIGNS THAT THIS CLRG WILL TAKE A BIT LONGER IN EC NY...WHERE THERE IS HIGHER TERRAIN. THIS MAKES SENSE AND WILL HOLD ONTO CLDS A LITTLE LONGER IN THESE AREAS. REST OF AREA SEES CLRG FOR A TIME THIS EVENING. AFTER THE CLDS CLEAR OUT THIS EVENING...HIGHER CLDS FROM THE NEXT SYSTEM BEGIN TO SPREAD ACROSS NY AND PA. THE SFC RDG AXIS IS E OF THE REGION TONIGHT AS THE NEXT SYSTEM RAPIDLY APPRCHES FROM THE SRN PLAINS AND UPR MIDWEST. THE LL FLO WILL TURN SWRLY AND SHUD KEEP TEMPS FROM BOTTOMING OUT MUCH BELOW 30 MOST PLACES. THE EXCEPTION IS IN NE PA/SERN NY WHERE THE WINDS WILL REMAIN LIGHT ENUF WITH CLR SKIES. THUS MINS WILL BE HIGHER IN THE NW CWA LOW 30S AND LOWER IN THE SE CWA MID TO UPPER 20S OR SO. FOR TUESDAY...CLDS WILL INCREASE THRU THE DAY AS STRG WAA/ISEN LIFT TAKES PLACE THRU A DEEPER AND DEEPER LAYER AS THE DAY PROGRESSES. TEMPS FROM THE SFC THRU 850 MB WILL BE WARM ENUF FOR ALL RAIN ENTIRE CWA. ALL SYNOPTIC SCALE MODELS INDICATE THAT THE RAIN WILL MOVE IN DURING THE AFTERNOON. WILL RAMP POPS UP BTWN 18Z TUE AND 00Z WED. && .SHORT TERM /TUESDAY NIGHT THROUGH WEDNESDAY NIGHT/... THE 12Z EURO...18Z NAM...12Z GFS HAVE TRENDED MORE TOWARD THE WEST WITH THE SFC LO AND ALL INDICATE THAT THE 850 MB LOW TRACKS TO WRN NY BY 00Z WED. THIS WILL ALLOW 850 MB TEMPS TO CLIMB WELL ABV FRZG AS THE PRECIP WORKS IN. WITH BNDRY LAYER TEMPS EXPECTED ABV FRZG...PRECIP WILL BE MAINLY RAIN AT THE ONSET. IN ADDTN...WITH THIS MORE WRN TRACK...THE DRY SLOT WITH THE DEVELOPING CYCLONE MOVES RIGHT THRU NE PA AND C NY TUE EVE. COLDER AIR DOES NOT SURGE IN UNTIL THE BULK OF THE MOISTURE AND LIFT WITH THE STORM IS NE OF OUR AREA. THUS...IT LOOKS LIKE A RAIN EVENT...POSSIBLY MIXED WITH SLEET/SNOW FINGER LAKES/UPR MOHAWK/TUG HILL TUE EVE...THEN WRAP AROUND SNOW AND SNOW SHOWERS ENHANCED BY MOISTURE FROM LAKE ONTARIO TUE NGT/ERLY WED. THE SNOW SHOWERS WILL CONT WED IN C NY AS THE WRAP AROUND SNOW SHOWERS TRANSITIONS TO LAKE EFFECT SNOWS. THE INVERSION RAPIDLY DROPS DOWN TO 900 MB BY 00Z THU. THUS THERE WILL BE SOME LES...BUT IT SHUD NOT BE A MAJOR EVENT. MOST OF THE SNOW WILL FALL WED AM...IN NC NY WITH THE COMBINATION OF LAKE EFFECT AND SYNOPTIC MOISTURE. SEE 2-5 INCHES OF SNOW IN NC NY...WITH AN INCH OR LESS SC NY/FAR NRN PA AND LITTLE IF ANY IN THE REST OF NE PA. ANOTHER CONCERN IS THE POTENTIAL FOR HIGH WINDS ON WEDNESDAY AS THE DEEPENING CYCLONE DEPARTS ACRS LWR QUEBEC. MOS GUIDC SUGGESTS LOW END WIND ADVY CRITERIA. ISALLABORIC PRESSURE RISES ARE RUNNING CLOSE TO 10 MB/6 HR WHICH IS ALSO BORDERLINE FOR WIND ADVY. SO WILL HIGHLIGHT IN HWO FOR ENTIRE CWA...AND WILL HIGH POTENTIAL FOR SOME SNOW IN NC NY AS WELL. BY WED NGT...LES SNOW SHOWERS AND FLURRIES RAPIDLY COME TO AN END AS THE LL FLO TURNS MORE WRLY IN ADVANCE OF THE NEXT SYSTEM. && .LONG TERM /THURSDAY THROUGH MONDAY/... THE LONG TERM WILL BE DOMINATED BY A BRISK WEST TO EAST FLOW, AS THE STRONGLY POSITIVE PNA PATTERN RELAXES. THE RESULT WILL BE A SERIES OF CLIPPERS AND FAST MOVING SYSTEMS TRAVERSING THE GREAT LAKES AND SOUTHERN ONTARIO PROVINCE. HOWEVER BY LATE IN THE PERIOD, A JET WILL DIVE INTO THE PLAINS AND CARVE OUT ANOTHER DEEP TROUGH OVER THE WEST-CENTRAL UNITED STATES. THIS WILL CAUSE THE POSITIVE PNA PATTERN TO BEGIN TO STRENGTHEN AGAIN, WITH RISING HEIGHTS INTO THE EASTERN CONUS. AS A RESULT, WE ARE FORECASTING LOW POP, BRIEF DURATION RW/SW EVENTS WITH LITTLE ACCUMULATION ANTICIPATED. WE ARE ALSO FORECASTING TEMPERATURES SLIGHTLY ABOVE NORMAL FOR THE THURSDAY TO MONDAY PERIOD. && .AVIATION /23Z MONDAY THROUGH SATURDAY/... CLOUDS HAVE MOVED EASTWARD, AWAY FROM THE TERMINALS LEAVING VFR CONDITIONS UNDER MOSTLY CLEAR SKIES. IT WILL BE A QUIET OVERNIGHT WITH LIGHT WINDS AND CIRRUS OVERHEAD. MVFR TO BORDER LINE IFR CONDITIONS WILL ARRIVE WITH RAIN ON TUESDAY AFTERNOON. THE RAIN MAKE IT TO THE AVP AND ELM TERMINALS BETWEEN 16Z AND 18Z, THEN SPREAD NORTHEAST TOWARD SYR AND RME BETWEEN 19Z AND 21Z. .OUTLOOK... TUE NGT/WED MORN...MVFR IN RAIN DROPPING TO IFR IN SNOW SHOWERS TUESDAY NIGHT. WED AFTN/THU...VFR. FRI/SAT...MAINLY VFR. POSSIBLE MVFR IN BRIEF SNOW SHOWERS. && .BGM WATCHES/WARNINGS/ADVISORIES... PA...NONE. NY...NONE. && $$ SYNOPSIS...DJN NEAR TERM...DJN SHORT TERM...DJN LONG TERM...DJP AVIATION...DJP
AREA FORECAST DISCUSSION
NWS BUFFALO NY
327 PM EST SUN DEC 25 2011 .SYNOPSIS... LOW PRESSURE WILL QUICKLY PASS TO THE NORTH OVERNIGHT...BRINGING A PERIOD OF RAIN OR SNOW SHOWERS...WHICH WILL TRANSITION TO SNOW SHOWERS AS COLDER AIR WORKS IN LATER TONIGHT. THIS SHOULD NOT BRING MUCH ACCUMULATION TO MOST...EXCEPT FOR HIGHER TERRAIN IN THE SOUTHERN TIER...AND EAST OF LAKE ONTARIO...WHERE A FEW INCHES OF SNOW ARE POSSIBLE. ANY LINGERING SNOW SHOWERS WILL QUICKLY END MONDAY AS HIGH PRESSURE BUILDS INTO THE LOWER LAKES. LOW PRESSURE TRACKING ACROSS NEW ENGLAND WILL BRING RAIN...WHICH WILL TRANSITION TO SNOW TUESDAY NIGHT. && .NEAR TERM /THROUGH MONDAY/... THROUGH THE REMAINDER OF THE AFTERNOON...GUSTY WINDS WILL CONTINUE ON THE NIAGARA FRONTIER...WITH GUSTS UP TO 40 MPH. AS WINDS SHIFT MORE SW IN RESPONSE TO THE APPROACHING SHORTWAVE...WINDS WILL PICK UP FURTHER TO THE EAST...WITH GUSTS TO 30 MPH BECOMING MORE COMMONPLACE TOWARD THIS EVENING. TEMPERATURES ARE QUITE A BIT ABOVE NORMAL IN WESTERN NEW YORK...WITH MOST LOCATIONS WELL INTO THE 40S. AFTER THIS...EYES TURN TO AN APPROACHING SHORTWAVE...WHICH WILL CROSS THE REGION TONIGHT...EVENTUALLY USHERING COLDER AIR INTO THE REGION. WHILE FAIRLY POTENT...THE SHORTWAVE IS FAIRLY MOISTURE STARVED...DEPENDING ON MOST OF ITS MOISTURE FROM THE LAKES. MODEL GUIDANCE IS IN FAIRLY GOOD AGREEMENT...WITH THE CAUSE OF PRECIPITATION A COMBINATION BETWEEN MODEST LEVELS OF LAKE INDUCED STABILITY COMBINED WITH THE SHORTWAVE. THE HRRR BASICALLY IS PAINTING A SHARPER PICTURE OF THE NAM/RGEM SOLUTIONS. THIS PROVIDES RATHER GOOD CONFIDENCE IN THE GENERAL IDEA OF RAIN AND SHOWERS MOVING ACROSS THE REGION THIS EVENING...THEN LINGERING LAKE EFFECT SNOW SHOWERS LATE TONIGHT SSE OF THE LAKES. FOR MOST...THIS WILL PROBABLY BRING LITTLE...IF ANY...ACCUMULATING SNOWFALL. THE NAM12/RGEM/HRRR ALL FORECAST MEAGER QPF (MEAN OF THE MODELS HAS ABOUT 0.05 INCHES) IN THE BUFFALO/ROCHESTER METRO AREAS...AS MUCH OF THE MOISTURE WILL THE SHORTWAVE PICKS UP WILL BE TOO LATE FOR THESE LOCATIONS. FOR THE CITIES...EXPECT RAIN OR SNOW SHOWERS FROM AROUND SUNSET THROUGH LATE THIS EVENING...THEN POSSIBLY A LINGERING SNOW SHOWER OVERNIGHT. THINGS ARE MORE INTERESTING EAST OF LAKE ONTARIO...WHERE IT IS CLOSEST TO THE SHORTWAVE...AND IN BEING DOWNSTREAM OF BOTH LAKES IT WILL HAVE THE BEST OPPORTUNITY TO PICK UP MOISTURE. BOTH 00Z AND 12Z MODEL RUNS...AS WELL AS THE HRRR...DEVELOP A DECENT BAND OUT AHEAD OF THE SHORTWAVE...WHICH SHOULD DROP ACROSS THE EASTERN LAKE ONTARIO REGION THIS EVENING. ALONG THE LAKE SHORE...THIS WILL PROBABLY MAINLY BE A MIX OF RAIN AND SNOW...WHILE HIGHER ELEVATIONS (INCLUDING THE TUG HILL AND NORTHERN LEWIS COUNTY) SHOULD BE MAINLY SNOW. BASICALLY EXPECT 3 TO 5 INCHES OF SNOW ACROSS THE HIGHER TERRAIN IN LEWIS AND OSWEGO COUNTIES...AND WHILE CONFIDENCE IS MARGINAL FOR AN ADVISORY...WILL ISSUE ONE GIVEN THAT THE SNOW THAT DOES FALL SHOULD BE MODERATE TO HEAVY...WITH MOST FALLING IN A FEW HOURS AS THE SHORTWAVE CROSSES. DON/T EXPECT QUITE AS MUCH SNOW EAST OF LAKE ERIE...AS IT WILL BE FURTHER FROM THE SHORTWAVE...AND DOES NOT HAVE MUCH MOISTURE TO TAP INTO. STILL...THERE SHOULD BE SOME OROGRAPHIC ENHANCEMENT ON THE CHAUTAUQUA...WITH 2 TO 3 INCHES LIKELY ACROSS HIGHER TERRAIN...ONCE A MIX OF RAIN AND SNOW SHOWERS CHANGES OVER TO SNOW SHOWERS AS COLDER AIR FILTERS IN DURING THE EVENING HOURS. THE SHORTWAVE WILL EXIT EAST LATE TONIGHT...WITH SNOW SHOWERS TAPERING OFF IN MOST LOCATIONS. THE NW FLOW SHOULD SUPPORT LIGHT LAKE EFFECT SNOW SHOWERS TO LINGER SE OF LAKE ONTARIO...FOCUSED ON WAYNE/CAYUGA AND POSSIBLY PORTIONS OF MONROE AND OSWEGO COUNTIES THROUGH EARLY MONDAY MORNING. THIS MAY PRODUCE AN INCH OR TWO. FOR MONDAY...HIGH PRESSURE WILL RIDGE NORTH FROM THE APPALACHIANS. WHILE THE DAY SHOULD START OFF WITH A FAIR AMOUNT OF LINGERING CLOUDS...SKIES SHOULD GRADUALLY CLEAR ACROSS WESTERN NEW YORK. WHILE COOLER...HIGHS WILL STILL BE ABOVE NORMAL...AS SHOT OF COLD AIR IS QUITE NARROW. BY THE AFTERNOON HOURS...850 MB TEMPERATURES WILL ALREADY BE WARMING...AS THE UPPER LEVEL RIDGE AXIS APPROACHES. HIGHS SHOULD MAINLY BE IN THE UPPER 30S ACROSS WESTERN NEW YORK...IN THE LOWER 30S EAST OF LAKE ONTARIO. && .SHORT TERM /MONDAY NIGHT THROUGH THURSDAY NIGHT/... THE HIGH PRESSURE RIDGE WILL SLIDE OFF THE EAST COAST MONDAY NIGHT. CLEAR SKIES WILL HAVE AN INCREASE IN CLOUDINESS LATE IN THE NIGHT. RADIATIONAL COOLING EARLY IN THE NIGHT WILL LOWER THE TEMPS TO THEIR LOWS IN THE UPPER 20S TO LOWER 30S...THEN STRONGER SOUTHERLY WINDS WILL RAISE THE TEMPS FROM THE LATE OVERNIGHT HOURS TO DAYBREAK. ON TUESDAY...ECMWF AND GFS ARE COMING CLOSER TO A COMMON SOLUTION WITH RESPECT TO THE MERGER OF AN OPING CLOSED LOW IN THE SOUTHERN STREAM PHASING WITH AN BEING ABSORBED BY A DIGGING OPEN WAVE IN THE NORTHERN STREAM. THE PHASING OF THE SYSTEMS WILL PRODUCING A FULL LATITUDE TROUGH FROM THE LOWER MISSISSIPPI VALLEY NORTH TO HUDSON BAY WITH A SURFACE LOW FORMING JUST SOUTH OF THE LOWER OHIO VALLEY. THE WARM AND MOIST INFLUX TO THE EAST OF THIS TROUGH AND SURFACE LOW WILL YIELD A WET PRECIP PATTERN FOR MUCH OF THE DAYLIGHT HOURS OF TUESDAY. 850MB TEMPS AT 12Z TUESDAY RANGE FROM +4C TO +6C...BUT WILL COOL RAPIDLY DURING THE AFTERNOON AS THE SURFACE LOW MOVES FROM SOUTH OF THE OHIO VALLEY TO THE UPPER CHESAPEAKE BAY BY THE EVENING. PRECIP WILL START AS RAIN BUT MIX WITH WET SNOW AS THE 0C ISOTHERM MOVES EASTWARD...THE -2C ISOTHERM DURING THE AFTERNOON AND -6C BY EVENING. AS THE SURFACE LOW LIFTS FURTHER NORTHEAST ALONG THE NEW ENGLAND COAST TUESDAY NIGHT...COLD ADVECTION ON ITS BACKSIDE WILL INCREASE. THIS WILL DELIVER A PROGRESSIVELY COLDER AIRMASS INTO OUR REGION...RESULTING IN ANY PRECIP CHANGING OVER FROM RAIN TO ALL SNOW. THE ISSUE OF THE STRENGTH OF THE PHASING OF NORTHERN AND SOUTHERN BRANCH TROUGHS WILL ALSO LIMIT THE STRENGTH OF THE SNOW ALONG THE WESTERN EDGE OF THIS SYSTEM AS IT EXITS THE REGION. WHERE THERE HAD BEEN GREATER DIFFERENCES AND DISCREPANCIES AMONG THE VARIOUS MODELS...THE 12Z RUNS OF GFS/ECMWF/GEM/NAM ARE ALL SHOWING A WELL DEFINED UPPER TROUGH OF RESPECTABLE MERIDIONAL AMPLITUDE BUT DO DIFFER ON THE DEVELOPMENT AND TRACK OF THE SURFACE LOWS...BUT ALL SFC LOWS WILL BE EAST OF OUR FORECAST AREA WITH A TRAILING COLD DEFORMATION ZONE CAPABLE OF PRODUCING A MEASURABLE SNOWFALL. I WILL KEEP WITH THE GFS/ECMWF SOLUTION AND EXPECT THERE TO BE A FAIR AMOUNT OF SNOW OVER THE CENTRAL AND NORTHERN PORTIONS OF THE STATE...FROM THE FINGER LAKES TO THE EASTERN LAKE ONTARIO REGION AND TUG HILL FOR OUR AREA OF CONCERN. WEDNESDAY SHOULD THEN FEATURE A GENERAL REPEAT OF MONDAY...AS THE COMBINATION OF INCREASING RIDGING/DRYING/SUBSIDENCE HELPS TO SHUT DOWN ANY LINGERING LAKE EFFECT DURING THE MORNING...AS WELL AS BRING A RETURN OF AT LEAST SOME PARTIAL SUNSHINE. WITH A MUCH COLDER AIRMASS IN PLACE /850 TEMPS RANGING FROM -12C TO -14C/...DAYTIME HIGHS WILL BE MUCH COLDER THAN TUESDAY`S...WITH READINGS RANGING GENERALLY IN THE MID 20S WITH TEENS FOR THE NORTH COUNTRY. CONTINUED DRY AND COLD WEATHER WILL THEN FOLLOW FOR WEDNESDAY NIGHT AS RIDGING CRESTS OVERHEAD AT ALL LEVELS...EXPECT TEMPS IN THE TEENS TO LOW 20S WITH SINGLE NUMBERS EAST OF LAKE ONTARIO. HIGH PRESSURE OVER THE REGION ON THURSDAY WILL MAINTAIN DRY WEATHER...WITH SOUTHERN FLOW DURING THE AFTERNOON BOOSTING TEMPS BACK ABOVE SEASONAL NORMALS IN THE MID TO UPPER 30S EXCEPT UPPER 20S TO LOW 30S EAST OF LAKE ONTARIO. && .LONG TERM /FRIDAY THROUGH SUNDAY/... IN THE EXTENDED PORTION OF THE FORECAST...BOUNDARY LAYER TEMPS WILL BECOME COLD ENOUGH THAT MOST PRECIP WILL BE IN THE FORM OF SNOW. THE EXCEPTION WILL BE ON FRIDAY AND ONLY DURING THE MIDDAY ARE TEMPS SUFFICIENTLY MILD ENOUGH FOR PRECIP TO BE RAIN OR A MIX OF RAIN AND SNOW. THERE WILL BE A CHANCE OF PRECIP EACH DAY DURING THE END OF THE WEEK AND THE WEEKEND AS UPPER WAVES MOVE ACROSS THE REGION. && .AVIATION /21Z SUNDAY THROUGH FRIDAY/... 18Z TAFS...EXPECT LARGELY VFR CONDITIONS TO PERSIST ACROSS THE REGION THROUGH THE AFTERNOON HOURS...THOUGH CIGS NEAR 3000 AT ART MAY RESULT IN BRIEF PERIODS OF MVFR CONDITIONS. AN UPPER LEVEL TROF AND ASSOCIATED COLD FRONT WILL CROSS THE REGION THIS EVENING. THIS WILL BRING A PERIOD OF SHOWERS...WHICH WILL START AS RAIN OR RAIN AND SNOW MIXED INITIALLY...BUT SHOULD TREND TOWARD SNOW AS COLDER AIR FILTERS IN LATER THIS EVENING. EXPECT CONDITIONS TO INITIALLY BE SLOW TO LOWER...WITH LOWERING CIGS AND PERIODS OF LOWER VSBY BEHIND THE TROF LATE EVENING AND OVERNIGHT. CONDITIONS SHOULD LARGELY BE MVFR...WITH PERIODS OF IFR OR LOWER IN MORE PERSISTENT SNOW SHOWERS. JHW/ART...WOULD BE MOST PRONE TO THESE LOWER CONDITIONS. CONDITIONS SHOULD IMPROVE MONDAY...AS CIGS LIFT AND SCATTER...THOUGH TIMING OF WHAT WILL LIKELY BE AN ABRUPT CLEARING IS ALWAYS TRICKY TO TIME. BY AFTERNOON...EXPECT ALL SITES TO BE VFR. OUTLOOK... MONDAY NIGHT...VFR. TUESDAY AND TUESDAY NIGHT...MVFR IN RAIN SHOWERS CHANGING TO SNOW SHOWERS TUESDAY NIGHT. POSSIBLY LOWER AT ART IN STEADIER SNOW. WEDNESDAY AND THURSDAY...MAINLY VFR. FRIDAY...VFR/MVFR. A CHANCE OF RAIN SHOWERS. && .MARINE... THROUGH MID-AFTERNOON...THE SSW FLOW HAS NOT PRODUCED VERY STRONG WINDS ON MOST OF THE NEAR SHORE WATERS...AS TEMPERATURES HAVE WARMED...AND LAND HAS HELPED SHIELD THE WATERS FROM STRONGER GUSTS. WINDS HAVE BEEN MUCH STRONGER ON THE NORTH SHORES...AND ARE LIKELY STRONGER THAN OBSERVATIONS ON THE SOUTH SHORES ARE SHOWING...JUST A FEW MILES OFFSHORE. THIS WILL CHANGE LATER THIS AFTERNOON...AS THE APPROACHING SHORTWAVE CAUSES WINDS TO SHIFT MORE SW AND WSW. THIS WILL CAUSE THE CHAUTAUQUA RIDGE TO HELP FUNNEL WINDS...RESULTING IN BETTER MIXING AND STRONGER SUSTAINED WINDS ALONG THE LAKE ERIE SHORELINE. FOR TONIGHT...WINDS WILL SHIFT TO THE NW BEHIND THE SHORTWAVE...AND WHILE WINDS ALOFT WILL WEAKEN...MIXING WILL IMPROVE WHICH WILL CAUSE WINDS TO MAINTAIN A DECENT FLOW OVERNIGHT. A NARROW RIDGE OF HIGH PRESSURE WILL BUILD ACROSS THE WATERS MONDAY...ALLOWING A BRIEF PERIOD OF CALMER WATERS BEFORE THE NEXT SYSTEM APPROACHES MONDAY NIGHT. A FAIRLY EXTENDED PERIOD OF SMALL CRAFT ADVISORY CONDITIONS ARE LIKELY THROUGH MID WEEK...AS LOW PRESSURE DEVELOPS AND TRACKS INTO NEW ENGLAND TUESDAY NIGHT. THIS SHOULD MAINTAIN A DECENT FLOW ACROSS THE WATERS...UNTIL HIGH PRESSURE FINALLY BUILDS IN FOR THE LATTER HALF OF THE WEEK. && .BUF WATCHES/WARNINGS/ADVISORIES... NY...LAKE EFFECT SNOW ADVISORY FROM 7 PM THIS EVENING TO 7 AM EST MONDAY FOR NYZ006-008. MARINE...SMALL CRAFT ADVISORY UNTIL MIDNIGHT EST TONIGHT FOR LEZ020. SMALL CRAFT ADVISORY UNTIL 10 AM EST MONDAY FOR LEZ040-041. SMALL CRAFT ADVISORY UNTIL MIDNIGHT EST TONIGHT FOR LOZ030. SMALL CRAFT ADVISORY UNTIL 4 PM EST MONDAY FOR LOZ043>045. SMALL CRAFT ADVISORY UNTIL 10 AM EST MONDAY FOR LOZ042. && $$ SYNOPSIS...APFFEL NEAR TERM...APFFEL SHORT TERM...WCH LONG TERM...WCH AVIATION...APFFEL MARINE...APFFEL/WCH
AREA FORECAST DISCUSSION
NWS BUFFALO NY
113 PM EST SUN DEC 25 2011 .SYNOPSIS... IT WILL BE A RATHER WINDY AND MILD CHRISTMAS DAY WITH A MIX OF CLOUDS AND A LITTLE SUNSHINE FOR MOST OF THE DAY. A COLD FRONT AND UPPER LEVEL DISTURBANCE WILL CROSS THE REGION LATE THIS AFTERNOON AND THIS EVENING WITH A ROUND OF LIGHT SNOW SHOWERS FOR MUCH OF THE REGION BRIEFLY BEGINNING AS RAIN. ACCUMULATIONS WILL BE VERY LIMITED EXCEPT ACROSS THE HIGHER TERRAIN OF THE WESTERN SOUTHERN TIER AND TUG HILL REGION WHERE SEVERAL INCHES OF SNOW IS POSSIBLE. ANY LINGERING SNOW SHOWERS WILL QUICKLY END MONDAY AS HIGH PRESSURE BUILDS INTO THE LOWER LAKES. LOW PRESSURE WILL BRING MORE UNSETTLED WEATHER TUESDAY WITH SOME LIGHT RAIN ENDING AS A BRIEF PERIOD OF LIGHT SNOW TUESDAY NIGHT. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... WHILE EARLY MORNING CLOUDS HAVE LARGELY GIVEN WAY TO AT LEAST SOME SUNSHINE...A FEW SNOW SHOWERS OR FLURRIES HAVE DEVELOPED EAT OF LAKE ONTARIO. THESE WILL BE SHORT LIVED AS THEY RACE OFF TO THE EAST...BUT A DUSTING IS POSSIBLE ACROSS HIGHER ELEVATIONS OF LEWIS COUNTY. BY LATE THIS AFTERNOON A STRONG SHORTWAVE WILL BE ON OUR DOORSTEP. LARGE SCALE FORCING FOR ASCENT WILL QUICKLY INCREASE AFTER 21Z AS STRONG DPVA AND HEIGHT FALLS OVERSPREAD THE LOWER LAKES. THE NEW 12Z NAM AND HRRR ARE A TAD SLOWER (AN HOUR OR TWO) WITH THE START OF THE SHOWERS. EXPECT SCATTERED SHOWERS TO DEVELOP AROUND SUNSET ACROSS WESTERN NY AND THE NORTH COUNTRY THEN QUICKLY SPREAD ACROSS THE REMAINDER OF THE REGION THROUGH EARLY EVENING. THIS SHOULD KEEP THE VAST MAJORITY OF THE DAYLIT HOURS DRY ACROSS WESTERN NEW YORK. NAM/GFS BUFKIT PROFILES SHOW THE BOUNDARY LAYER INITIALLY WARM ENOUGH FOR MUCH OF THIS TO BE RAIN AT THE START...BUT COLD AIR ADVECTION AND EVAPORATE COOLING WILL QUICKLY CHANGE THE RAIN OVER TO SNOW BY MID TO LATE EVENING. THIS SYSTEM IS FAST MOVING AND RELATIVELY MOISTURE STARVED...SO THIS WILL GREATLY LIMIT ACCUMULATIONS IN MOST AREAS ESPECIALLY CONSIDERING THE MILD START AT THE ONSET OF PRECIP. THE MAJORITY OF THE LOWER ELEVATIONS ACROSS THE REGION WILL SEE LESS THAN AN INCH...AND PERHAPS NOTHING AT ALL IN SOME AREAS CLOSE TO THE LAKESHORES. THERE WILL BE TWO NOTABLE EXCEPTIONS TO THIS HOWEVER... EAST OF LAKE ONTARIO BUFKIT PROFILES AND MESOSCALE MODEL DATA BOTH SUPPORT A SHORT WINDOW OF SEVERAL HOURS FROM MID TO LATE EVENING WHERE CONDITIONS BECOME FAVORABLE FOR LAKE ENHANCEMENT NEAR THE TIME OF THE COLD FRONTAL PASSAGE. NAM BUFKIT PROFILES BRING LAKE INDUCED EQUILIBRIUM LEVELS ALL THE WAY UP TO 15K FEET FOR A FEW HOURS WITH WELL ALIGNED WESTERLY FLOW. THIS SHOULD SET THE STAGE FOR LAKE ENHANCEMENT AT THE EAST END OF THE LAKE...MAXIMIZED ACROSS THE TUG HILL IN THE FAVORED UPSLOPE AREAS. THE SNOW COULD BECOME QUITE HEAVY FOR A BRIEF PERIOD OF TIME...BUT THE SHORT DURATION WILL PREVENT ANY BIG ACCUMULATIONS. HAVE GONE WITH 3-4 INCHES ACROSS THE TUG HILL REGION FOR TONIGHT. HELD OFF ON ADVISORY FOR NOW GIVEN THE MARGINAL SNOW NUMBERS AND THE FACT THAT THE GREATER ACCUMULATIONS WILL BE LIMITED TO A SMALL AREA ACROSS HIGHER TERRAIN...BUT DAY SHIFT MAY NEED TO CONSIDER A HEADLINE. ACROSS LOWER ELEVATIONS MARGINAL BOUNDARY LAYER TEMPS WILL GREATLY LIMIT ACCUMULATIONS...ESPECIALLY CLOSER TO THE LAKE ONTARIO SHORE WHERE VERY LITTLE ACCUMULATION IS EXPECTED. AFTER MIDNIGHT THE LAKE ENHANCEMENT WILL EVOLVE INTO PURE LAKE EFFECT BUT QUICKLY MOVE TO SOUTHEAST OF THE LAKE AS THE BOUNDARY LAYER FLOW BECOMES NORTHWEST. THIS WILL SET UP RELATIVELY WEAK SNOW SHOWERS FROM NEAR ROCHESTER OVER TO OSWEGO COUNTY AND DOWN INTO THE FINGER LAKES. MAY SEE SOME SPOTTY ONE INCH AMOUNTS FROM THIS...ESPECIALLY FROM THE EASTERN SUBURBS OF ROCHESTER INTO WAYNE COUNTY. QUICK DRYING OF THE SYNOPTIC BACKGROUND AND VERY MARGINAL INSTABILITY AFTER MIDNIGHT WILL PREVENT ANYTHING MORE SIGNIFICANT. THE OTHER AREA OF CONCERN IS ACROSS THE CHAUTAUQUA RIDGE. NAM BUFKIT PROFILES SUGGEST A WINDOW FROM ABOUT 03Z-09Z WHERE NORTHWEST UPSLOPE FLOW AND MODEST LAKE ENHANCEMENT WILL BECOME FAVORABLE FOR MINOR ACCUMULATIONS IN THE TYPICAL AREAS ALONG THE RIDGE LINE FROM SHERMAN UP THROUGH MAYVILLE TO PERRYSBURG. AGAIN THE QUICK DRYING OUT OF THE SYNOPTIC MOISTURE AND SHORT FETCH/LIMITED INSTABILITY WILL PREVENT ANY SIGNIFICANT ACCUMULATIONS...BUT MAY SEE 2-4 INCH AMOUNTS IN SOME AREAS. MAY ALSO SEE 1-2 INCH AMOUNTS FARTHER NORTH ACROSS THE BOSTON HILLS AND WYOMING COUNTY...ALTHOUGH THE FLOW QUICKLY ESTABLISHES TOO MUCH NORTHERLY COMPONENT FOR MUCH LAKE ENHANCEMENT IN THOSE AREAS. ALL OF THIS SHOULD BE ON THE WANE BEFORE DAYBREAK MONDAY AS A RIDGE OF HIGH PRESSURE BUILDS TOWARDS LAKE ERIE AND MOISTURE QUICKLY DECREASES. && .SHORT TERM /6 PM THIS EVENING THROUGH WEDNESDAY NIGHT/... FOLLOWING THE PASSAGE OF TODAY`S SYSTEM...STRONG RIDGING WILL BUILD ACROSS THE AREA AT ALL LEVELS ON MONDAY. ASSOCIATED STRONG DRYING AND SUBSIDENCE WILL BRING A QUICK END TO ANY LINGERING LAKE EFFECT SNOW SHOWERS SOUTHEAST OF LAKE ONTARIO IN THE MORNING...ALONG WITH THE RETURN OF A DECENT AMOUNT OF SUNSHINE. WITH A SEASONABLY COLDER AIRMASS IN PLACE...DAYTIME TEMPS WILL BE CLOSER TO NORMAL FOR LATE DECEMBER...OR IN THE LOWER TO MID 30S. DURING MONDAY NIGHT...THE AFOREMENTIONED RIDGE WILL SLIDE OFF THE EAST COAST...ALLOWING A PAIR OF SHORTWAVE TROUGHS...ONE IN THE NORTHERN STREAM AND ONE IN THE SOUTHERN STREAM...TO APPROACH THE AREA FROM THE NATION`S MIDSECTION. IN ADVANCE OF THESE FEATURES...A DEEP SOUTHWESTERLY FLOW OF MILDER AIR WILL OVERSPREAD THE AREA... WITH THE RESULTING WARM AIR ADVECTION LEADING TO BOTH AN INCREASE IN CLOUD COVER AND A NON-DIURNAL TEMPERATURE TREND...WITH TEMPS STEADILY RISING AFTER EARLY EVENING LOWS IN THE MID 20S TO LOWER 30S. WITH THE NAM/GFS/GEM AND ECMWF NOW ALL IN GOOD AGREEMENT THAT ANY PRECIP WILL REMAIN SAFELY WEST OF THE AREA THROUGH THE NIGHT...HAVE PULLED ANY MENTION OF PRECIP FROM LATE MONDAY NIGHT. ON TUESDAY...THE AFOREMENTIONED PAIR OF TROUGHS WILL CONTINUE TO ADVANCE ON THE REGION FROM THE WEST...WITH THE VARIOUS GUIDANCE PACKAGES CONTINUING TO SHOW DISPARITIES WITH RESPECT TO EXACTLY HOW MUCH THESE FEATURES PHASE TOGETHER AS THEY APPROACH. AT THIS TIME...THE SPREAD IN THE GUIDANCE CURRENTLY RANGES FROM THE UNPHASED 00Z NAM/GFS/GEM SOLUTIONS TO THE 00Z ECMWF...WHICH SHOWS THE TWO WAVES MERGING INTO A RATHER SHARP FULL LATITUDE TROUGH. REGARDLESS OF WHICH OF THESE SCENARIOS YOU BELIEVE...ALL GENERALLY DEPICT A DEVELOPING LOW PRESSURE SYSTEM QUICKLY LIFTING NORTHEAST FROM THE TENNESSEE VALLEY TO THE MID ATLANTIC STATES ON TUESDAY...WITH AN ASSOCIATED RIBBON OF MOISTURE AND LIFT SPREADING NORTHEAST ACROSS OUR REGION. THIS SHOULD RESULT IN A LIKELIHOOD OF PRECIP SPREADING NORTHEAST ACROSS THE REGION DURING THE DAY. AS FOR PTYPE...EXPECTED MILD BOUNDARY LAYER TEMPS IN THE 40S AND 850 MB TEMPS OF ZERO TO -4C SHOULD BE SUPPORTIVE OF MAINLY RAIN RIGHT THROUGH THE DAY...WITH PERHAPS A LITTLE SNOW MIXING IN LATE AS THE COLUMN BEGINS TO COOL A BIT MORE STRONGLY. AS THE SURFACE LOW LIFTS FURTHER NORTHEAST ALONG THE NEW ENGLAND COAST TUESDAY NIGHT...COLD ADVECTION ON ITS BACKSIDE WILL INCREASE. THIS WILL DELIVER A PROGRESSIVELY COLDER AIRMASS INTO OUR REGION...RESULTING IN ANY PRECIP CHANGING OVER FROM RAIN TO ALL SNOW. THE MAIN ISSUE DURING THIS TIME FRAME WILL BE HOW QUICKLY THE PRECIP TAPERS OFF...WHICH WILL DIRECTLY INFLUENCE POTENTIAL SNOWFALL ACCUMULATIONS AND WILL BE A DIRECT FUNCTION OF EXACTLY MUCH PHASING OF THE NORTHERN AND SOUTHERN STREAMS OCCURS. THE FULLY PHASED ECMWF SOLUTION WOULD SUPPORT A STRONGER AND SLOWER MOVING SURFACE LOW ON A MORE WESTERLY TRACK...AND WOULD DELIVER COLDER AIR MORE STRONGLY WHILE ALSO MAINTAINING PRECIP ACROSS THE AREA LONGER...THEREBY RESULTING IN WHAT WOULD BE A WIDESPREAD ACCUMULATING SNOW. IN CONTRAST...THE LESS PHASED NAM/GFS/GEM SOLUTIONS OFFER WEAKER COLD ADVECTION AND A MUCH QUICKER END TO THE SYNOPTIC-SCALE PRECIP...RESULTING IN MUCH MORE LIMITED ACCUMULATIONS AFTER THE CHANGEOVER. WITH HPC PREFERENCES CURRENTLY TOWARD A FASTER...MORE NON-PHASED SOLUTION LED BY THE CANADIAN GEM...FOR NOW WILL ELECT TO GO WITH A FASTER END TO THE MAIN SWATH OF SYNOPTIC SCALE PRECIP TUESDAY NIGHT...WITH LAKE-DRIVEN SNOW SHOWERS TAKING OVER AS A NORTHERLY FLOW OF PROGRESSIVELY COLDER AIR SPREADS ACROSS THE AREA OVERNIGHT. THIS SHOULD STILL RESULT IN AT LEAST SOME LIMITED ACCUMULATIONS IN MANY AREAS BY MORNING...THOUGH THE SHORT NORTHERLY FETCH AND INCREASINGLY DRY AIRMASS SHOULD KEEP THESE FROM GETTING OUT OF HAND. WEDNESDAY SHOULD THEN FEATURE A GENERAL REPEAT OF MONDAY...AS THE COMBINATION OF INCREASING RIDGING/DRYING/SUBSIDENCE HELPS TO SHUT DOWN ANY LINGERING LAKE EFFECT DURING THE MORNING...AS WELL AS BRING A RETURN TO AT LEAST SOME PARTIAL SUNSHINE. WITH A MUCH COLDER AIRMASS IN PLACE /850 TEMPS AVERAGING AROUND -10C/...DAYTIME HIGHS WILL BE MUCH COLDER THAN TUESDAY`S...WITH READINGS RANGING FROM THE MID 20S ACROSS THE NORTH COUNTRY TO AROUND 30 ELSEWHERE. CONTINUED DRY BUT SEASONABLY CHILLY WEATHER WILL THEN FOLLOW FOR WEDNESDAY NIGHT AS RIDGING CRESTS OVERHEAD AT ALL LEVELS. && .LONG TERM /THURSDAY THROUGH SATURDAY/... IN THE EXTENDED PORTION OF THE FORECAST...SLOWLY DEPARTING SURFACE RIDGING IS EXPECTED TO KEEP A CONTINUATION OF MAINLY DRY WEATHER ACROSS OUR REGION THROUGH THURSDAY. THEREAFTER...ONE OR MORE WAVES OF LOW PRESSURE ZIPPING ALONG IN A PERSISTENT FAST ZONAL FLOW WILL BRING RENEWED PRECIP CHANCES FOR BOTH FRIDAY AND NEW YEAR`S EVE. AS IS USUALLY THE CASE IN SUCH A PATTERN...THE MEDIUM RANGE GUIDANCE CONTINUES TO HAVE TROUBLE COMING INTO CONVERGENCE ON THE TIMING AND EXACT POSITIONING OF SUCH SYSTEMS...SO BROADBRUSH CHANCE POPS WILL REMAIN IN ORDER FOR THE END OF THE WEEK. WITH THE PREVAILING ZONAL FLOW...SOME MODERATION IN TEMPS FROM WEDNESDAY`S COLDER READINGS SHOULD DEVELOP...WHICH SHOULD BE SUPPORTIVE OF A RAIN/SNOW SHOWER MIX DEPENDING UPON THE TIME OF DAY. && .AVIATION /18Z SUNDAY THROUGH FRIDAY/... 18Z TAFS...EXPECT LARGELY VFR CONDITIONS TO PERSIST ACROSS THE REGION THROUGH THE AFTERNOON HOURS...THOUGH CIGS NEAR 3000 AT ART MAY RESULT IN BRIEF PERIODS OF MVFR CONDITIONS. AN UPPER LEVEL TROF AND ASSOCIATED COLD FRONT WILL CROSS THE REGION THIS EVENING. THIS WILL BRING A PERIOD OF SHOWERS...WHICH WILL START AS RAIN OR RAIN AND SNOW MIXED INITIALLY...BUT SHOULD TREND TOWARD SNOW AS COLDER AIR FILTERS IN LATER THIS EVENING. EXPECT CONDITIONS TO INITIALLY BE SLOW TO LOWER...WITH LOWERING CIGS AND PERIODS OF LOWER VSBY BEHIND THE TROF LATE EVENING AND OVERNIGHT. CONDITIONS SHOULD LARGELY BE MVFR...WITH PERIODS OF IFR OR LOWER IN MORE PERSISTENT SNOW SHOWERS. JHW/ART...WOULD BE MOST PRONE TO THESE LOWER CONDITIONS. CONDITIONS SHOULD IMPROVE MONDAY...AS CIGS LIFT AND SCATTER...THOUGH TIMING OF WHAT WILL LIKELY BE AN ABRUPT CLEARING IS ALWAYS TRICKY TO TIME. BY AFTERNOON...EXPECT ALL SITES TO BE VFR. OUTLOOK... MONDAY NIGHT...VFR. TUESDAY AND TUESDAY NIGHT...MVFR IN RAIN SHOWERS CHANGING TO SNOW SHOWERS TUESDAY NIGHT. POSSIBLY LOWER AT ART IN STEADIER SNOW. WEDNESDAY AND THURSDAY...MAINLY VFR. FRIDAY...VFR/MVFR. A CHANCE OF RAIN SHOWERS. && .MARINE... A MODERATE TO STRONG PRESSURE GRADIENT WILL DEVELOP TODAY ACROSS THE LOWER LAKES BETWEEN LOW PRESSURE OVER NORTHERN QUEBEC AND HIGH PRESSURE OVER THE SOUTHEAST STATES. A LOW LEVEL JET WILL PEAK THIS AFTERNOON AT 40 KNOTS...HOWEVER NOT ALL OF THIS WILL MIX DOWN TO THE LAKE SURFACE. BEST WINDS THROUGH MID-MORNING HAVE BEEN ON THE NORTH SHORES OF EACH OF THE LAKES...WITH SURFACE TEMPERATURES IN THE UPPER 30S ADVECTING ACROSS WATER TEMPS IN THE LOWER 40S. TEMPERATURES WILL WARM INTO THIS AFTERNOON...SO WHILE THE LOW LEVEL JET STRENGTHENS...LESS MIXING SHOULD OFFSET THIS. WITH WINDS SHIFTING MORE WSW LATE AFTERNOON...FUNNELING SHOULD BRIEFLY PUSH WINDS TO 30 KTS ON EASTERN PORTIONS OF LAKE ERIE. THE LOW LEVEL JET WILL DIMINISH BEHIND THE FRONT...BUT BETTER MIXING IN THE COLD AIR ADVECTION WILL KEEP WINDS UP OVERNIGHT ACROSS THE LAKES. WINDS AND WAVES WILL SUBSIDE MONDAY AS A NARROW RIDGE OF HIGH PRESSURE BUILDS OVER THE LOWER LAKES. THIS WILL BE SHORT LIVED AS THE PRESSURE GRADIENT PICKS UP AGAIN MONDAY NIGHT AHEAD OF THE NEXT LOW MOVING ACROSS ONTARIO AND QUEBEC...PRODUCING MORE SMALL CRAFT ADVISORY CONDITIONS. && .CLIMATE... BUFFALO AND ROCHESTER AIRPORTS OFFICIALLY HAD NOW SNOW ON THE GROUND ON CHRISTMAS MORNING...MAKING 2011 A GREEN CHRISTMAS FOR BOTH LOCATIONS. WHETHER IT IS A WHITE CHRISTMAS OR NOT IS BASED ON THE READING TAKING AT 700 AM ON CHRISTMAS MORNING...SO EVEN IF MEASURABLE SNOW DOES OCCUR THIS EVENING...IT WOULD BE TOO LATE FOR THE RECORD BOOKS. HOWEVER...SATELLITE SHOWS SOME SNOW ACROSS PORTIONS OF THE SOUTHERN TIER AND A FEW OF THE FAR SOUTH TOWNS...AS WELL AS THE TUG HILL...SO THOSE IN SEARCH OF SNOW TO NOT HAVE TO GO TOO FAR. THE WINTER OF 2011-12 HAS STARTED AT A RECORD SLOW PACE IN THE SNOWFALL CATEGORY ACROSS WESTERN AND CENTRAL NEW YORK. THROUGH DECEMBER 24TH...THE CURRENT SNOW THIS SEASON OF 3.0 INCHES (BUFFALO) AND 2.5 INCHES (ROCHESTER) ARE WELL BELOW NORMAL THUS FAR. THERE HAVE BEEN SEVERAL YEARS THAT HAVE HAD SIMILAR STARTS THOUGH. BELOW IS A LIST OF THE LEAST AMOUNT OF SNOW IN BOTH CITIES IN PREVIOUS YEARS ON RECORD...MEASURED AT THE RESPECTIVE AIRPORTS...THROUGH AND INCLUDING CHRISTMAS EVE. BUFFALO 1 3.0 2011 2 3.1 1998 3 3.3 1931 4 3.6 1896 5 4.3 1918 ... 10 6.5 1888 ... 15 7.8 1891 ***NORMAL THROUGH DECEMBER 24TH 29.1*** ROCHESTER 1 2.5 2011 2 2.6 1939 3 3.7 2001 4 3.8 1877 5 4.2 2006 ... 10 6.2 1998 ... 15 7.8 1940 ***NORMAL THROUGH DECEMBER 24TH 23.5*** SNOWFALL RECORDS GO BACK TO THE WINTER OF 1884-85. && .BUF WATCHES/WARNINGS/ADVISORIES... NY...NONE. MARINE...SMALL CRAFT ADVISORY UNTIL 4 AM EST MONDAY FOR LEZ020. SMALL CRAFT ADVISORY UNTIL 10 AM EST MONDAY FOR LEZ040-041. SMALL CRAFT ADVISORY UNTIL 4 AM EST MONDAY FOR LOZ030. SMALL CRAFT ADVISORY UNTIL 4 PM EST MONDAY FOR LOZ043>045. SMALL CRAFT ADVISORY UNTIL 10 AM EST MONDAY FOR LOZ042. && $$ SYNOPSIS...HITCHCOCK NEAR TERM...APFFEL/HITCHCOCK SHORT TERM...JJR LONG TERM...JJR AVIATION...APFFEL MARINE...APFFEL/HITCHCOCK CLIMATE...THOMAS/HITCHCOCK/JJR/APFFEL
AREA FORECAST DISCUSSION
NWS BUFFALO NY
1158 AM EST SUN DEC 25 2011 .SYNOPSIS... IT WILL BE A RATHER WINDY AND MILD CHRISTMAS DAY WITH A MIX OF CLOUDS AND A LITTLE SUNSHINE FOR MOST OF THE DAY. A COLD FRONT AND UPPER LEVEL DISTURBANCE WILL CROSS THE REGION LATE THIS AFTERNOON AND THIS EVENING WITH A ROUND OF LIGHT SNOW SHOWERS FOR MUCH OF THE REGION BRIEFLY BEGINNING AS RAIN. ACCUMULATIONS WILL BE VERY LIMITED EXCEPT ACROSS THE HIGHER TERRAIN OF THE WESTERN SOUTHERN TIER AND TUG HILL REGION WHERE SEVERAL INCHES OF SNOW IS POSSIBLE. ANY LINGERING SNOW SHOWERS WILL QUICKLY END MONDAY AS HIGH PRESSURE BUILDS INTO THE LOWER LAKES. LOW PRESSURE WILL BRING MORE UNSETTLED WEATHER TUESDAY WITH SOME LIGHT RAIN ENDING AS A BRIEF PERIOD OF LIGHT SNOW TUESDAY NIGHT. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... WHILE EARLY MORNING CLOUDS HAVE LARGELY GIVEN WAY TO AT LEAST SOME SUNSHINE...A FEW SNOW SHOWERS OR FLURRIES HAVE DEVELOPED EAT OF LAKE ONTARIO. THESE WILL BE SHORT LIVED AS THEY RACE OFF TO THE EAST...BUT A DUSTING IS POSSIBLE ACROSS HIGHER ELEVATIONS OF LEWIS COUNTY. BY LATE THIS AFTERNOON A STRONG SHORTWAVE WILL BE ON OUR DOORSTEP. LARGE SCALE FORCING FOR ASCENT WILL QUICKLY INCREASE AFTER 21Z AS STRONG DPVA AND HEIGHT FALLS OVERSPREAD THE LOWER LAKES. THE NEW 12Z NAM AND HRRR ARE A TAD SLOWER (AN HOUR OR TWO) WITH THE START OF THE SHOWERS. EXPECT SCATTERED SHOWERS TO DEVELOP AROUND SUNSET ACROSS WESTERN NY AND THE NORTH COUNTRY THEN QUICKLY SPREAD ACROSS THE REMAINDER OF THE REGION THROUGH EARLY EVENING. THIS SHOULD KEEP THE VAST MAJORITY OF THE DAYLIT HOURS DRY ACROSS WESTERN NEW YORK. NAM/GFS BUFKIT PROFILES SHOW THE BOUNDARY LAYER INITIALLY WARM ENOUGH FOR MUCH OF THIS TO BE RAIN AT THE START...BUT COLD AIR ADVECTION AND EVAPORATE COOLING WILL QUICKLY CHANGE THE RAIN OVER TO SNOW BY MID TO LATE EVENING. THIS SYSTEM IS FAST MOVING AND RELATIVELY MOISTURE STARVED...SO THIS WILL GREATLY LIMIT ACCUMULATIONS IN MOST AREAS ESPECIALLY CONSIDERING THE MILD START AT THE ONSET OF PRECIP. THE MAJORITY OF THE LOWER ELEVATIONS ACROSS THE REGION WILL SEE LESS THAN AN INCH...AND PERHAPS NOTHING AT ALL IN SOME AREAS CLOSE TO THE LAKESHORES. THERE WILL BE TWO NOTABLE EXCEPTIONS TO THIS HOWEVER... EAST OF LAKE ONTARIO BUFKIT PROFILES AND MESOSCALE MODEL DATA BOTH SUPPORT A SHORT WINDOW OF SEVERAL HOURS FROM MID TO LATE EVENING WHERE CONDITIONS BECOME FAVORABLE FOR LAKE ENHANCEMENT NEAR THE TIME OF THE COLD FRONTAL PASSAGE. NAM BUFKIT PROFILES BRING LAKE INDUCED EQUILIBRIUM LEVELS ALL THE WAY UP TO 15K FEET FOR A FEW HOURS WITH WELL ALIGNED WESTERLY FLOW. THIS SHOULD SET THE STAGE FOR LAKE ENHANCEMENT AT THE EAST END OF THE LAKE...MAXIMIZED ACROSS THE TUG HILL IN THE FAVORED UPSLOPE AREAS. THE SNOW COULD BECOME QUITE HEAVY FOR A BRIEF PERIOD OF TIME...BUT THE SHORT DURATION WILL PREVENT ANY BIG ACCUMULATIONS. HAVE GONE WITH 3-4 INCHES ACROSS THE TUG HILL REGION FOR TONIGHT. HELD OFF ON ADVISORY FOR NOW GIVEN THE MARGINAL SNOW NUMBERS AND THE FACT THAT THE GREATER ACCUMULATIONS WILL BE LIMITED TO A SMALL AREA ACROSS HIGHER TERRAIN...BUT DAY SHIFT MAY NEED TO CONSIDER A HEADLINE. ACROSS LOWER ELEVATIONS MARGINAL BOUNDARY LAYER TEMPS WILL GREATLY LIMIT ACCUMULATIONS...ESPECIALLY CLOSER TO THE LAKE ONTARIO SHORE WHERE VERY LITTLE ACCUMULATION IS EXPECTED. AFTER MIDNIGHT THE LAKE ENHANCEMENT WILL EVOLVE INTO PURE LAKE EFFECT BUT QUICKLY MOVE TO SOUTHEAST OF THE LAKE AS THE BOUNDARY LAYER FLOW BECOMES NORTHWEST. THIS WILL SET UP RELATIVELY WEAK SNOW SHOWERS FROM NEAR ROCHESTER OVER TO OSWEGO COUNTY AND DOWN INTO THE FINGER LAKES. MAY SEE SOME SPOTTY ONE INCH AMOUNTS FROM THIS...ESPECIALLY FROM THE EASTERN SUBURBS OF ROCHESTER INTO WAYNE COUNTY. QUICK DRYING OF THE SYNOPTIC BACKGROUND AND VERY MARGINAL INSTABILITY AFTER MIDNIGHT WILL PREVENT ANYTHING MORE SIGNIFICANT. THE OTHER AREA OF CONCERN IS ACROSS THE CHAUTAUQUA RIDGE. NAM BUFKIT PROFILES SUGGEST A WINDOW FROM ABOUT 03Z-09Z WHERE NORTHWEST UPSLOPE FLOW AND MODEST LAKE ENHANCEMENT WILL BECOME FAVORABLE FOR MINOR ACCUMULATIONS IN THE TYPICAL AREAS ALONG THE RIDGE LINE FROM SHERMAN UP THROUGH MAYVILLE TO PERRYSBURG. AGAIN THE QUICK DRYING OUT OF THE SYNOPTIC MOISTURE AND SHORT FETCH/LIMITED INSTABILITY WILL PREVENT ANY SIGNIFICANT ACCUMULATIONS...BUT MAY SEE 2-4 INCH AMOUNTS IN SOME AREAS. MAY ALSO SEE 1-2 INCH AMOUNTS FARTHER NORTH ACROSS THE BOSTON HILLS AND WYOMING COUNTY...ALTHOUGH THE FLOW QUICKLY ESTABLISHES TOO MUCH NORTHERLY COMPONENT FOR MUCH LAKE ENHANCEMENT IN THOSE AREAS. ALL OF THIS SHOULD BE ON THE WANE BEFORE DAYBREAK MONDAY AS A RIDGE OF HIGH PRESSURE BUILDS TOWARDS LAKE ERIE AND MOISTURE QUICKLY DECREASES. && .SHORT TERM /6 PM THIS EVENING THROUGH WEDNESDAY NIGHT/... FOLLOWING THE PASSAGE OF TODAY`S SYSTEM...STRONG RIDGING WILL BUILD ACROSS THE AREA AT ALL LEVELS ON MONDAY. ASSOCIATED STRONG DRYING AND SUBSIDENCE WILL BRING A QUICK END TO ANY LINGERING LAKE EFFECT SNOW SHOWERS SOUTHEAST OF LAKE ONTARIO IN THE MORNING...ALONG WITH THE RETURN OF A DECENT AMOUNT OF SUNSHINE. WITH A SEASONABLY COLDER AIRMASS IN PLACE...DAYTIME TEMPS WILL BE CLOSER TO NORMAL FOR LATE DECEMBER...OR IN THE LOWER TO MID 30S. DURING MONDAY NIGHT...THE AFOREMENTIONED RIDGE WILL SLIDE OFF THE EAST COAST...ALLOWING A PAIR OF SHORTWAVE TROUGHS...ONE IN THE NORTHERN STREAM AND ONE IN THE SOUTHERN STREAM...TO APPROACH THE AREA FROM THE NATION`S MIDSECTION. IN ADVANCE OF THESE FEATURES...A DEEP SOUTHWESTERLY FLOW OF MILDER AIR WILL OVERSPREAD THE AREA... WITH THE RESULTING WARM AIR ADVECTION LEADING TO BOTH AN INCREASE IN CLOUD COVER AND A NON-DIURNAL TEMPERATURE TREND...WITH TEMPS STEADILY RISING AFTER EARLY EVENING LOWS IN THE MID 20S TO LOWER 30S. WITH THE NAM/GFS/GEM AND ECMWF NOW ALL IN GOOD AGREEMENT THAT ANY PRECIP WILL REMAIN SAFELY WEST OF THE AREA THROUGH THE NIGHT...HAVE PULLED ANY MENTION OF PRECIP FROM LATE MONDAY NIGHT. ON TUESDAY...THE AFOREMENTIONED PAIR OF TROUGHS WILL CONTINUE TO ADVANCE ON THE REGION FROM THE WEST...WITH THE VARIOUS GUIDANCE PACKAGES CONTINUING TO SHOW DISPARITIES WITH RESPECT TO EXACTLY HOW MUCH THESE FEATURES PHASE TOGETHER AS THEY APPROACH. AT THIS TIME...THE SPREAD IN THE GUIDANCE CURRENTLY RANGES FROM THE UNPHASED 00Z NAM/GFS/GEM SOLUTIONS TO THE 00Z ECMWF...WHICH SHOWS THE TWO WAVES MERGING INTO A RATHER SHARP FULL LATITUDE TROUGH. REGARDLESS OF WHICH OF THESE SCENARIOS YOU BELIEVE...ALL GENERALLY DEPICT A DEVELOPING LOW PRESSURE SYSTEM QUICKLY LIFTING NORTHEAST FROM THE TENNESSEE VALLEY TO THE MID ATLANTIC STATES ON TUESDAY...WITH AN ASSOCIATED RIBBON OF MOISTURE AND LIFT SPREADING NORTHEAST ACROSS OUR REGION. THIS SHOULD RESULT IN A LIKELIHOOD OF PRECIP SPREADING NORTHEAST ACROSS THE REGION DURING THE DAY. AS FOR PTYPE...EXPECTED MILD BOUNDARY LAYER TEMPS IN THE 40S AND 850 MB TEMPS OF ZERO TO -4C SHOULD BE SUPPORTIVE OF MAINLY RAIN RIGHT THROUGH THE DAY...WITH PERHAPS A LITTLE SNOW MIXING IN LATE AS THE COLUMN BEGINS TO COOL A BIT MORE STRONGLY. AS THE SURFACE LOW LIFTS FURTHER NORTHEAST ALONG THE NEW ENGLAND COAST TUESDAY NIGHT...COLD ADVECTION ON ITS BACKSIDE WILL INCREASE. THIS WILL DELIVER A PROGRESSIVELY COLDER AIRMASS INTO OUR REGION...RESULTING IN ANY PRECIP CHANGING OVER FROM RAIN TO ALL SNOW. THE MAIN ISSUE DURING THIS TIME FRAME WILL BE HOW QUICKLY THE PRECIP TAPERS OFF...WHICH WILL DIRECTLY INFLUENCE POTENTIAL SNOWFALL ACCUMULATIONS AND WILL BE A DIRECT FUNCTION OF EXACTLY MUCH PHASING OF THE NORTHERN AND SOUTHERN STREAMS OCCURS. THE FULLY PHASED ECMWF SOLUTION WOULD SUPPORT A STRONGER AND SLOWER MOVING SURFACE LOW ON A MORE WESTERLY TRACK...AND WOULD DELIVER COLDER AIR MORE STRONGLY WHILE ALSO MAINTAINING PRECIP ACROSS THE AREA LONGER...THEREBY RESULTING IN WHAT WOULD BE A WIDESPREAD ACCUMULATING SNOW. IN CONTRAST...THE LESS PHASED NAM/GFS/GEM SOLUTIONS OFFER WEAKER COLD ADVECTION AND A MUCH QUICKER END TO THE SYNOPTIC-SCALE PRECIP...RESULTING IN MUCH MORE LIMITED ACCUMULATIONS AFTER THE CHANGEOVER. WITH HPC PREFERENCES CURRENTLY TOWARD A FASTER...MORE NON-PHASED SOLUTION LED BY THE CANADIAN GEM...FOR NOW WILL ELECT TO GO WITH A FASTER END TO THE MAIN SWATH OF SYNOPTIC SCALE PRECIP TUESDAY NIGHT...WITH LAKE-DRIVEN SNOW SHOWERS TAKING OVER AS A NORTHERLY FLOW OF PROGRESSIVELY COLDER AIR SPREADS ACROSS THE AREA OVERNIGHT. THIS SHOULD STILL RESULT IN AT LEAST SOME LIMITED ACCUMULATIONS IN MANY AREAS BY MORNING...THOUGH THE SHORT NORTHERLY FETCH AND INCREASINGLY DRY AIRMASS SHOULD KEEP THESE FROM GETTING OUT OF HAND. WEDNESDAY SHOULD THEN FEATURE A GENERAL REPEAT OF MONDAY...AS THE COMBINATION OF INCREASING RIDGING/DRYING/SUBSIDENCE HELPS TO SHUT DOWN ANY LINGERING LAKE EFFECT DURING THE MORNING...AS WELL AS BRING A RETURN TO AT LEAST SOME PARTIAL SUNSHINE. WITH A MUCH COLDER AIRMASS IN PLACE /850 TEMPS AVERAGING AROUND -10C/...DAYTIME HIGHS WILL BE MUCH COLDER THAN TUESDAY`S...WITH READINGS RANGING FROM THE MID 20S ACROSS THE NORTH COUNTRY TO AROUND 30 ELSEWHERE. CONTINUED DRY BUT SEASONABLY CHILLY WEATHER WILL THEN FOLLOW FOR WEDNESDAY NIGHT AS RIDGING CRESTS OVERHEAD AT ALL LEVELS. && .LONG TERM /THURSDAY THROUGH SATURDAY/... IN THE EXTENDED PORTION OF THE FORECAST...SLOWLY DEPARTING SURFACE RIDGING IS EXPECTED TO KEEP A CONTINUATION OF MAINLY DRY WEATHER ACROSS OUR REGION THROUGH THURSDAY. THEREAFTER...ONE OR MORE WAVES OF LOW PRESSURE ZIPPING ALONG IN A PERSISTENT FAST ZONAL FLOW WILL BRING RENEWED PRECIP CHANCES FOR BOTH FRIDAY AND NEW YEAR`S EVE. AS IS USUALLY THE CASE IN SUCH A PATTERN...THE MEDIUM RANGE GUIDANCE CONTINUES TO HAVE TROUBLE COMING INTO CONVERGENCE ON THE TIMING AND EXACT POSITIONING OF SUCH SYSTEMS...SO BROADBRUSH CHANCE POPS WILL REMAIN IN ORDER FOR THE END OF THE WEEK. WITH THE PREVAILING ZONAL FLOW...SOME MODERATION IN TEMPS FROM WEDNESDAY`S COLDER READINGS SHOULD DEVELOP...WHICH SHOULD BE SUPPORTIVE OF A RAIN/SNOW SHOWER MIX DEPENDING UPON THE TIME OF DAY. && .AVIATION /18Z SUNDAY THROUGH FRIDAY/... THROUGH 15Z...LINGERING MVFR CIGS ARE CONFINED TO THE NIAGARA FRONTIER...WITH THIS BAND ERODING AS FORECAST BY MOST MODELS. EXPECT ALL SITES TO BE VFR FOR MUCH OF TODAY...BEFORE A SHORTWAVE BRINGS SHOWERS AND LOWERING CONDITIONS THIS EVENING. SCATTERED RAIN SHOWERS WILL DEVELOP LATE THIS AFTERNOON AND EARLY EVENING BEFORE MIXING WITH AND CHANGING TO SNOW SHOWERS OVERNIGHT. EXPECT CIGS/VSBY TO BE VFR AT FIRST AS THE LOW LEVELS REMAIN UNSATURATED. CONDITIONS WILL DETERIORATE TO MVFR BY MID TO LATE EVENING AS SNOW SHOWERS BECOME MORE WIDESPREAD. SOME IFR WILL DEVELOP AS WELL IN MORE PERSISTENT SNOW EAST OF LAKES ERIE AND ONTARIO. THIS WILL TARGET THE CHAUTAUQUA RIDGE INCLUDING KJHW OFF LAKE ERIE...AND THE TUG HILL REGION BETWEEN KART AND KSYR EAST OF LAKE ONTARIO. OUTLOOK... MONDAY...VFR/MVFR WITH WITH MORNING SNOW SHOWERS SOUTHEAST OF THE LAKES...THEN VFR. TUESDAY AND TUESDAY NIGHT...MVFR IN RAIN SHOWERS CHANGING TO SNOW SHOWERS TUESDAY NIGHT. WEDNESDAY AND THURSDAY...MAINLY VFR. && .MARINE... A MODERATE TO STRONG PRESSURE GRADIENT WILL DEVELOP TODAY ACROSS THE LOWER LAKES BETWEEN LOW PRESSURE OVER NORTHERN QUEBEC AND HIGH PRESSURE OVER THE SOUTHEAST STATES. A LOW LEVEL JET WILL PEAK THIS AFTERNOON AT 40 KNOTS...HOWEVER NOT ALL OF THIS WILL MIX DOWN TO THE LAKE SURFACE. BEST WINDS THROUGH MID-MORNING HAVE BEEN ON THE NORTH SHORES OF EACH OF THE LAKES...WITH SURFACE TEMPERATURES IN THE UPPER 30S ADVECTING ACROSS WATER TEMPS IN THE LOWER 40S. TEMPERATURES WILL WARM INTO THIS AFTERNOON...SO WHILE THE LOW LEVEL JET STRENGTHENS...LESS MIXING SHOULD OFFSET THIS. WITH WINDS SHIFTING MORE WSW LATE AFTERNOON...FUNNELING SHOULD BRIEFLY PUSH WINDS TO 30 KTS ON EASTERN PORTIONS OF LAKE ERIE. THE LOW LEVEL JET WILL DIMINISH BEHIND THE FRONT...BUT BETTER MIXING IN THE COLD AIR ADVECTION WILL KEEP WINDS UP OVERNIGHT ACROSS THE LAKES. WINDS AND WAVES WILL SUBSIDE MONDAY AS A NARROW RIDGE OF HIGH PRESSURE BUILDS OVER THE LOWER LAKES. THIS WILL BE SHORT LIVED AS THE PRESSURE GRADIENT PICKS UP AGAIN MONDAY NIGHT AHEAD OF THE NEXT LOW MOVING ACROSS ONTARIO AND QUEBEC...PRODUCING MORE SMALL CRAFT ADVISORY CONDITIONS. && .CLIMATE... BUFFALO AND ROCHESTER AIRPORTS OFFICIALLY HAD NOW SNOW ON THE GROUND ON CHRISTMAS MORNING...MAKING 2011 A GREEN CHRISTMAS FOR BOTH LOCATIONS. WHETHER IT IS A WHITE CHRISTMAS OR NOT IS BASED ON THE READING TAKING AT 700 AM ON CHRISTMAS MORNING...SO EVEN IF MEASURABLE SNOW DOES OCCUR THIS EVENING...IT WOULD BE TOO LATE FOR THE RECORD BOOKS. HOWEVER...SATELLITE SHOWS SOME SNOW ACROSS PORTIONS OF THE SOUTHERN TIER AND A FEW OF THE FAR SOUTH TOWNS...AS WELL AS THE TUG HILL...SO THOSE IN SEARCH OF SNOW TO NOT HAVE TO GO TOO FAR. THE WINTER OF 2011-12 HAS STARTED AT A RECORD SLOW PACE IN THE SNOWFALL CATEGORY ACROSS WESTERN AND CENTRAL NEW YORK. THROUGH DECEMBER 24TH...THE CURRENT SNOW THIS SEASON OF 3.0 INCHES (BUFFALO) AND 2.5 INCHES (ROCHESTER) ARE WELL BELOW NORMAL THUS FAR. THERE HAVE BEEN SEVERAL YEARS THAT HAVE HAD SIMILAR STARTS THOUGH. BELOW IS A LIST OF THE LEAST AMOUNT OF SNOW IN BOTH CITIES IN PREVIOUS YEARS ON RECORD...MEASURED AT THE RESPECTIVE AIRPORTS...THROUGH AND INCLUDING CHRISTMAS EVE. BUFFALO 1 3.0 2011 2 3.1 1998 3 3.3 1931 4 3.6 1896 5 4.3 1918 ... 10 6.5 1888 ... 15 7.8 1891 ***NORMAL THROUGH DECEMBER 24TH 29.1*** ROCHESTER 1 2.5 2011 2 2.6 1939 3 3.7 2001 4 3.8 1877 5 4.2 2006 ... 10 6.2 1998 ... 15 7.8 1940 ***NORMAL THROUGH DECEMBER 24TH 23.5*** SNOWFALL RECORDS GO BACK TO THE WINTER OF 1884-85. && .BUF WATCHES/WARNINGS/ADVISORIES... NY...NONE. MARINE...SMALL CRAFT ADVISORY UNTIL 4 AM EST MONDAY FOR LEZ020. SMALL CRAFT ADVISORY UNTIL 10 AM EST MONDAY FOR LEZ040-041. SMALL CRAFT ADVISORY UNTIL 4 AM EST MONDAY FOR LOZ030. SMALL CRAFT ADVISORY UNTIL 4 PM EST MONDAY FOR LOZ043>045. SMALL CRAFT ADVISORY UNTIL 10 AM EST MONDAY FOR LOZ042. && $$ SYNOPSIS...HITCHCOCK NEAR TERM...APFFEL/HITCHCOCK SHORT TERM...JJR LONG TERM...JJR AVIATION...APFFEL/HITCHCOCK MARINE...APFFEL/HITCHCOCK CLIMATE...THOMAS/HITCHCOCK/JJR/APFFEL
AREA FORECAST DISCUSSION
NWS BUFFALO NY
1040 AM EST SUN DEC 25 2011 .SYNOPSIS... IT WILL BE A RATHER WINDY AND MILD CHRISTMAS DAY WITH A MIX OF CLOUDS AND A LITTLE SUNSHINE FOR MOST OF THE DAY. A COLD FRONT AND UPPER LEVEL DISTURBANCE WILL CROSS THE REGION LATE THIS AFTERNOON AND THIS EVENING WITH A ROUND OF LIGHT SNOW SHOWERS FOR MUCH OF THE REGION BRIEFLY BEGINNING AS RAIN. ACCUMULATIONS WILL BE VERY LIMITED EXCEPT ACROSS THE HIGHER TERRAIN OF THE WESTERN SOUTHERN TIER AND TUG HILL REGION WHERE SEVERAL INCHES OF SNOW IS POSSIBLE. ANY LINGERING SNOW SHOWERS WILL QUICKLY END MONDAY AS HIGH PRESSURE BUILDS INTO THE LOWER LAKES. LOW PRESSURE WILL BRING MORE UNSETTLED WEATHER TUESDAY WITH SOME LIGHT RAIN ENDING AS A BRIEF PERIOD OF LIGHT SNOW TUESDAY NIGHT. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... FOR MOST OF TODAY THE WARM SECTOR WILL BE ESTABLISHED WITH 850MB TEMPS RISING TO AROUND -1C BY MIDDAY. THE EARLY MORNING CLOUD COVER SHOULD GIVE WAY TO AT LEAST A FEW BREAKS OF SUNSHINE THROUGH THE COURSE OF THE DAY. TEMPERATURES WILL ONCE AGAIN RISE ABOVE AVERAGE WITH THE LAKE PLAINS TOPPING OUT IN THE LOWER 40S...AND UPPER 30S ACROSS THE HIGHER TERRAIN. IT WILL CONTINUE TO BE BREEZY...ESPECIALLY ALONG LAKE ERIE AND THE NIAGARA FRONTIER WHERE GUSTS OF 35 TO 40 MPH ARE EXPECTED THROUGH THIS AFTERNOON. BY LATE THIS AFTERNOON A STRONG SHORTWAVE WILL BE ON OUR DOORSTEP. LARGE SCALE FORCING FOR ASCENT WILL QUICKLY INCREASE AFTER 21Z AS STRONG DPVA AND HEIGHT FALLS OVERSPREAD THE LOWER LAKES. THE NEW 12Z NAM AND HRRR ARE A TAD SLOWER (AN HOUR OR TWO) WITH THE START OF THE SHOWERS. EXPECT SCATTERED SHOWERS TO DEVELOP AROUND SUNSET ACROSS WESTERN NY AND THE NORTH COUNTRY THEN QUICKLY SPREAD ACROSS THE REMAINDER OF THE REGION THROUGH EARLY EVENING. THIS SHOULD KEEP THE VAST MAJORITY OF THE DAYLIT HOURS DRY ACROSS WESTERN NEW YORK. NAM/GFS BUFKIT PROFILES SHOW THE BOUNDARY LAYER INITIALLY WARM ENOUGH FOR MUCH OF THIS TO BE RAIN AT THE START...BUT COLD AIR ADVECTION AND EVAPORATE COOLING WILL QUICKLY CHANGE THE RAIN OVER TO SNOW BY MID TO LATE EVENING. THIS SYSTEM IS FAST MOVING AND RELATIVELY MOISTURE STARVED...SO THIS WILL GREATLY LIMIT ACCUMULATIONS IN MOST AREAS ESPECIALLY CONSIDERING THE MILD START AT THE ONSET OF PRECIP. THE MAJORITY OF THE LOWER ELEVATIONS ACROSS THE REGION WILL SEE LESS THAN AN INCH...AND PERHAPS NOTHING AT ALL IN SOME AREAS CLOSE TO THE LAKESHORES. THERE WILL BE TWO NOTABLE EXCEPTIONS TO THIS HOWEVER... EAST OF LAKE ONTARIO BUFKIT PROFILES AND MESOSCALE MODEL DATA BOTH SUPPORT A SHORT WINDOW OF SEVERAL HOURS FROM MID TO LATE EVENING WHERE CONDITIONS BECOME FAVORABLE FOR LAKE ENHANCEMENT NEAR THE TIME OF THE COLD FRONTAL PASSAGE. NAM BUFKIT PROFILES BRING LAKE INDUCED EQUILIBRIUM LEVELS ALL THE WAY UP TO 15K FEET FOR A FEW HOURS WITH WELL ALIGNED WESTERLY FLOW. THIS SHOULD SET THE STAGE FOR LAKE ENHANCEMENT AT THE EAST END OF THE LAKE...MAXIMIZED ACROSS THE TUG HILL IN THE FAVORED UPSLOPE AREAS. THE SNOW COULD BECOME QUITE HEAVY FOR A BRIEF PERIOD OF TIME...BUT THE SHORT DURATION WILL PREVENT ANY BIG ACCUMULATIONS. HAVE GONE WITH 3-4 INCHES ACROSS THE TUG HILL REGION FOR TONIGHT. HELD OFF ON ADVISORY FOR NOW GIVEN THE MARGINAL SNOW NUMBERS AND THE FACT THAT THE GREATER ACCUMULATIONS WILL BE LIMITED TO A SMALL AREA ACROSS HIGHER TERRAIN...BUT DAY SHIFT MAY NEED TO CONSIDER A HEADLINE. ACROSS LOWER ELEVATIONS MARGINAL BOUNDARY LAYER TEMPS WILL GREATLY LIMIT ACCUMULATIONS...ESPECIALLY CLOSER TO THE LAKE ONTARIO SHORE WHERE VERY LITTLE ACCUMULATION IS EXPECTED. AFTER MIDNIGHT THE LAKE ENHANCEMENT WILL EVOLVE INTO PURE LAKE EFFECT BUT QUICKLY MOVE TO SOUTHEAST OF THE LAKE AS THE BOUNDARY LAYER FLOW BECOMES NORTHWEST. THIS WILL SET UP RELATIVELY WEAK SNOW SHOWERS FROM NEAR ROCHESTER OVER TO OSWEGO COUNTY AND DOWN INTO THE FINGER LAKES. MAY SEE SOME SPOTTY ONE INCH AMOUNTS FROM THIS...ESPECIALLY FROM THE EASTERN SUBURBS OF ROCHESTER INTO WAYNE COUNTY. QUICK DRYING OF THE SYNOPTIC BACKGROUND AND VERY MARGINAL INSTABILITY AFTER MIDNIGHT WILL PREVENT ANYTHING MORE SIGNIFICANT. THE OTHER AREA OF CONCERN IS ACROSS THE CHAUTAUQUA RIDGE. NAM BUFKIT PROFILES SUGGEST A WINDOW FROM ABOUT 03Z-09Z WHERE NORTHWEST UPSLOPE FLOW AND MODEST LAKE ENHANCEMENT WILL BECOME FAVORABLE FOR MINOR ACCUMULATIONS IN THE TYPICAL AREAS ALONG THE RIDGE LINE FROM SHERMAN UP THROUGH MAYVILLE TO PERRYSBURG. AGAIN THE QUICK DRYING OUT OF THE SYNOPTIC MOISTURE AND SHORT FETCH/LIMITED INSTABILITY WILL PREVENT ANY SIGNIFICANT ACCUMULATIONS...BUT MAY SEE 2-4 INCH AMOUNTS IN SOME AREAS. MAY ALSO SEE 1-2 INCH AMOUNTS FARTHER NORTH ACROSS THE BOSTON HILLS AND WYOMING COUNTY...ALTHOUGH THE FLOW QUICKLY ESTABLISHES TOO MUCH NORTHERLY COMPONENT FOR MUCH LAKE ENHANCEMENT IN THOSE AREAS. ALL OF THIS SHOULD BE ON THE WANE BEFORE DAYBREAK MONDAY AS A RIDGE OF HIGH PRESSURE BUILDS TOWARDS LAKE ERIE AND MOISTURE QUICKLY DECREASES. && .SHORT TERM /6 PM THIS EVENING THROUGH WEDNESDAY NIGHT/... FOLLOWING THE PASSAGE OF TODAY`S SYSTEM...STRONG RIDGING WILL BUILD ACROSS THE AREA AT ALL LEVELS ON MONDAY. ASSOCIATED STRONG DRYING AND SUBSIDENCE WILL BRING A QUICK END TO ANY LINGERING LAKE EFFECT SNOW SHOWERS SOUTHEAST OF LAKE ONTARIO IN THE MORNING...ALONG WITH THE RETURN OF A DECENT AMOUNT OF SUNSHINE. WITH A SEASONABLY COLDER AIRMASS IN PLACE...DAYTIME TEMPS WILL BE CLOSER TO NORMAL FOR LATE DECEMBER...OR IN THE LOWER TO MID 30S. DURING MONDAY NIGHT...THE AFOREMENTIONED RIDGE WILL SLIDE OFF THE EAST COAST...ALLOWING A PAIR OF SHORTWAVE TROUGHS...ONE IN THE NORTHERN STREAM AND ONE IN THE SOUTHERN STREAM...TO APPROACH THE AREA FROM THE NATION`S MIDSECTION. IN ADVANCE OF THESE FEATURES...A DEEP SOUTHWESTERLY FLOW OF MILDER AIR WILL OVERSPREAD THE AREA... WITH THE RESULTING WARM AIR ADVECTION LEADING TO BOTH AN INCREASE IN CLOUD COVER AND A NON-DIURNAL TEMPERATURE TREND...WITH TEMPS STEADILY RISING AFTER EARLY EVENING LOWS IN THE MID 20S TO LOWER 30S. WITH THE NAM/GFS/GEM AND ECMWF NOW ALL IN GOOD AGREEMENT THAT ANY PRECIP WILL REMAIN SAFELY WEST OF THE AREA THROUGH THE NIGHT...HAVE PULLED ANY MENTION OF PRECIP FROM LATE MONDAY NIGHT. ON TUESDAY...THE AFOREMENTIONED PAIR OF TROUGHS WILL CONTINUE TO ADVANCE ON THE REGION FROM THE WEST...WITH THE VARIOUS GUIDANCE PACKAGES CONTINUING TO SHOW DISPARITIES WITH RESPECT TO EXACTLY HOW MUCH THESE FEATURES PHASE TOGETHER AS THEY APPROACH. AT THIS TIME...THE SPREAD IN THE GUIDANCE CURRENTLY RANGES FROM THE UNPHASED 00Z NAM/GFS/GEM SOLUTIONS TO THE 00Z ECMWF...WHICH SHOWS THE TWO WAVES MERGING INTO A RATHER SHARP FULL LATITUDE TROUGH. REGARDLESS OF WHICH OF THESE SCENARIOS YOU BELIEVE...ALL GENERALLY DEPICT A DEVELOPING LOW PRESSURE SYSTEM QUICKLY LIFTING NORTHEAST FROM THE TENNESSEE VALLEY TO THE MID ATLANTIC STATES ON TUESDAY...WITH AN ASSOCIATED RIBBON OF MOISTURE AND LIFT SPREADING NORTHEAST ACROSS OUR REGION. THIS SHOULD RESULT IN A LIKELIHOOD OF PRECIP SPREADING NORTHEAST ACROSS THE REGION DURING THE DAY. AS FOR PTYPE...EXPECTED MILD BOUNDARY LAYER TEMPS IN THE 40S AND 850 MB TEMPS OF ZERO TO -4C SHOULD BE SUPPORTIVE OF MAINLY RAIN RIGHT THROUGH THE DAY...WITH PERHAPS A LITTLE SNOW MIXING IN LATE AS THE COLUMN BEGINS TO COOL A BIT MORE STRONGLY. AS THE SURFACE LOW LIFTS FURTHER NORTHEAST ALONG THE NEW ENGLAND COAST TUESDAY NIGHT...COLD ADVECTION ON ITS BACKSIDE WILL INCREASE. THIS WILL DELIVER A PROGRESSIVELY COLDER AIRMASS INTO OUR REGION...RESULTING IN ANY PRECIP CHANGING OVER FROM RAIN TO ALL SNOW. THE MAIN ISSUE DURING THIS TIME FRAME WILL BE HOW QUICKLY THE PRECIP TAPERS OFF...WHICH WILL DIRECTLY INFLUENCE POTENTIAL SNOWFALL ACCUMULATIONS AND WILL BE A DIRECT FUNCTION OF EXACTLY MUCH PHASING OF THE NORTHERN AND SOUTHERN STREAMS OCCURS. THE FULLY PHASED ECMWF SOLUTION WOULD SUPPORT A STRONGER AND SLOWER MOVING SURFACE LOW ON A MORE WESTERLY TRACK...AND WOULD DELIVER COLDER AIR MORE STRONGLY WHILE ALSO MAINTAINING PRECIP ACROSS THE AREA LONGER...THEREBY RESULTING IN WHAT WOULD BE A WIDESPREAD ACCUMULATING SNOW. IN CONTRAST...THE LESS PHASED NAM/GFS/GEM SOLUTIONS OFFER WEAKER COLD ADVECTION AND A MUCH QUICKER END TO THE SYNOPTIC-SCALE PRECIP...RESULTING IN MUCH MORE LIMITED ACCUMULATIONS AFTER THE CHANGEOVER. WITH HPC PREFERENCES CURRENTLY TOWARD A FASTER...MORE NON-PHASED SOLUTION LED BY THE CANADIAN GEM...FOR NOW WILL ELECT TO GO WITH A FASTER END TO THE MAIN SWATH OF SYNOPTIC SCALE PRECIP TUESDAY NIGHT...WITH LAKE-DRIVEN SNOW SHOWERS TAKING OVER AS A NORTHERLY FLOW OF PROGRESSIVELY COLDER AIR SPREADS ACROSS THE AREA OVERNIGHT. THIS SHOULD STILL RESULT IN AT LEAST SOME LIMITED ACCUMULATIONS IN MANY AREAS BY MORNING...THOUGH THE SHORT NORTHERLY FETCH AND INCREASINGLY DRY AIRMASS SHOULD KEEP THESE FROM GETTING OUT OF HAND. WEDNESDAY SHOULD THEN FEATURE A GENERAL REPEAT OF MONDAY...AS THE COMBINATION OF INCREASING RIDGING/DRYING/SUBSIDENCE HELPS TO SHUT DOWN ANY LINGERING LAKE EFFECT DURING THE MORNING...AS WELL AS BRING A RETURN TO AT LEAST SOME PARTIAL SUNSHINE. WITH A MUCH COLDER AIRMASS IN PLACE /850 TEMPS AVERAGING AROUND -10C/...DAYTIME HIGHS WILL BE MUCH COLDER THAN TUESDAY`S...WITH READINGS RANGING FROM THE MID 20S ACROSS THE NORTH COUNTRY TO AROUND 30 ELSEWHERE. CONTINUED DRY BUT SEASONABLY CHILLY WEATHER WILL THEN FOLLOW FOR WEDNESDAY NIGHT AS RIDGING CRESTS OVERHEAD AT ALL LEVELS. && .LONG TERM /THURSDAY THROUGH SATURDAY/... IN THE EXTENDED PORTION OF THE FORECAST...SLOWLY DEPARTING SURFACE RIDGING IS EXPECTED TO KEEP A CONTINUATION OF MAINLY DRY WEATHER ACROSS OUR REGION THROUGH THURSDAY. THEREAFTER...ONE OR MORE WAVES OF LOW PRESSURE ZIPPING ALONG IN A PERSISTENT FAST ZONAL FLOW WILL BRING RENEWED PRECIP CHANCES FOR BOTH FRIDAY AND NEW YEAR`S EVE. AS IS USUALLY THE CASE IN SUCH A PATTERN...THE MEDIUM RANGE GUIDANCE CONTINUES TO HAVE TROUBLE COMING INTO CONVERGENCE ON THE TIMING AND EXACT POSITIONING OF SUCH SYSTEMS...SO BROADBRUSH CHANCE POPS WILL REMAIN IN ORDER FOR THE END OF THE WEEK. WITH THE PREVAILING ZONAL FLOW...SOME MODERATION IN TEMPS FROM WEDNESDAY`S COLDER READINGS SHOULD DEVELOP...WHICH SHOULD BE SUPPORTIVE OF A RAIN/SNOW SHOWER MIX DEPENDING UPON THE TIME OF DAY. && .AVIATION /16Z SUNDAY THROUGH THURSDAY/... THROUGH 15Z...LINGERING MVFR CIGS ARE CONFINED TO THE NIAGARA FRONTIER...WITH THIS BAND ERODING AS FORECAST BY MOST MODELS. EXPECT ALL SITES TO BE VFR FOR MUCH OF TODAY...BEFORE A SHORTWAVE BRINGS SHOWERS AND LOWERING CONDITIONS THIS EVENING. SCATTERED RAIN SHOWERS WILL DEVELOP LATE THIS AFTERNOON AND EARLY EVENING BEFORE MIXING WITH AND CHANGING TO SNOW SHOWERS OVERNIGHT. EXPECT CIGS/VSBY TO BE VFR AT FIRST AS THE LOW LEVELS REMAIN UNSATURATED. CONDITIONS WILL DETERIORATE TO MVFR BY MID TO LATE EVENING AS SNOW SHOWERS BECOME MORE WIDESPREAD. SOME IFR WILL DEVELOP AS WELL IN MORE PERSISTENT SNOW EAST OF LAKES ERIE AND ONTARIO. THIS WILL TARGET THE CHAUTAUQUA RIDGE INCLUDING KJHW OFF LAKE ERIE...AND THE TUG HILL REGION BETWEEN KART AND KSYR EAST OF LAKE ONTARIO. OUTLOOK... MONDAY...VFR/MVFR WITH WITH MORNING SNOW SHOWERS SOUTHEAST OF THE LAKES...THEN VFR. TUESDAY AND TUESDAY NIGHT...MVFR IN RAIN SHOWERS CHANGING TO SNOW SHOWERS TUESDAY NIGHT. WEDNESDAY AND THURSDAY...MAINLY VFR. && .MARINE... A MODERATE TO STRONG PRESSURE GRADIENT WILL DEVELOP TODAY ACROSS THE LOWER LAKES BETWEEN LOW PRESSURE OVER NORTHERN QUEBEC AND HIGH PRESSURE OVER THE SOUTHEAST STATES. A LOW LEVEL JET WILL PEAK THIS AFTERNOON AT 40 KNOTS...HOWEVER NOT ALL OF THIS WILL MIX DOWN TO THE LAKE SURFACE. BEST WINDS THROUGH MID-MORNING HAVE BEEN ON THE NORTH SHORES OF EACH OF THE LAKES...WITH SURFACE TEMPERATURES IN THE UPPER 30S ADVECTING ACROSS WATER TEMPS IN THE LOWER 40S. TEMPERATURES WILL WARM INTO THIS AFTERNOON...SO WHILE THE LOW LEVEL JET STRENGTHENS...LESS MIXING SHOULD OFFSET THIS. WITH WINDS SHIFTING MORE WSW LATE AFTERNOON...FUNNELING SHOULD BRIEFLY PUSH WINDS TO 30 KTS ON EASTERN PORTIONS OF LAKE ERIE. THE LOW LEVEL JET WILL DIMINISH BEHIND THE FRONT...BUT BETTER MIXING IN THE COLD AIR ADVECTION WILL KEEP WINDS UP OVERNIGHT ACROSS THE LAKES. WINDS AND WAVES WILL SUBSIDE MONDAY AS A NARROW RIDGE OF HIGH PRESSURE BUILDS OVER THE LOWER LAKES. THIS WILL BE SHORT LIVED AS THE PRESSURE GRADIENT PICKS UP AGAIN MONDAY NIGHT AHEAD OF THE NEXT LOW MOVING ACROSS ONTARIO AND QUEBEC...PRODUCING MORE SMALL CRAFT ADVISORY CONDITIONS. && .CLIMATE... BUFFALO AND ROCHESTER AIRPORTS OFFICIALLY HAD NOW SNOW ON THE GROUND ON CHRISTMAS MORNING...MAKING 2011 A GREEN CHRISTMAS FOR BOTH LOCATIONS. WHETHER IT IS A WHITE CHRISTMAS OR NOT IS BASED ON THE READING TAKING AT 700 AM ON CHRISTMAS MORNING...SO EVEN IF MEASURABLE SNOW DOES OCCUR THIS EVENING...IT WOULD BE TOO LATE FOR THE RECORD BOOKS. HOWEVER...SATELLITE SHOWS SOME SNOW ACROSS PORTIONS OF THE SOUTHERN TIER AND A FEW OF THE FAR SOUTH TOWNS...AS WELL AS THE TUG HILL...SO THOSE IN SEARCH OF SNOW TO NOT HAVE TO GO TOO FAR. THE WINTER OF 2011-12 HAS STARTED AT A RECORD SLOW PACE IN THE SNOWFALL CATEGORY ACROSS WESTERN AND CENTRAL NEW YORK. THROUGH DECEMBER 24TH...THE CURRENT SNOW THIS SEASON OF 3.0 INCHES (BUFFALO) AND 2.5 INCHES (ROCHESTER) ARE WELL BELOW NORMAL THUS FAR. THERE HAVE BEEN SEVERAL YEARS THAT HAVE HAD SIMILAR STARTS THOUGH. BELOW IS A LIST OF THE LEAST AMOUNT OF SNOW IN BOTH CITIES IN PREVIOUS YEARS ON RECORD...MEASURED AT THE RESPECTIVE AIRPORTS...THROUGH AND INCLUDING CHRISTMAS EVE. BUFFALO 1 3.0 2011 2 3.1 1998 3 3.3 1931 4 3.6 1896 5 4.3 1918 ... 10 6.5 1888 ... 15 7.8 1891 ***NORMAL THROUGH DECEMBER 24TH 29.1*** ROCHESTER 1 2.5 2011 2 2.6 1939 3 3.7 2001 4 3.8 1877 5 4.2 2006 ... 10 6.2 1998 ... 15 7.8 1940 ***NORMAL THROUGH DECEMBER 24TH 23.5*** SNOWFALL RECORDS GO BACK TO THE WINTER OF 1884-85. && .BUF WATCHES/WARNINGS/ADVISORIES... NY...NONE. MARINE...SMALL CRAFT ADVISORY UNTIL 4 AM EST MONDAY FOR LEZ020. SMALL CRAFT ADVISORY UNTIL 10 AM EST MONDAY FOR LEZ040-041. SMALL CRAFT ADVISORY UNTIL 4 AM EST MONDAY FOR LOZ030. SMALL CRAFT ADVISORY UNTIL 4 PM EST MONDAY FOR LOZ043>045. SMALL CRAFT ADVISORY UNTIL 10 AM EST MONDAY FOR LOZ042. && $$ SYNOPSIS...HITCHCOCK NEAR TERM...APFFEL/HITCHCOCK SHORT TERM...JJR LONG TERM...JJR AVIATION...APFFEL/HITCHCOCK MARINE...APFFEL/HITCHCOCK CLIMATE...THOMAS/HITCHCOCK/JJR/APFFEL
AREA FORECAST DISCUSSION
NWS WILMINGTON NC
249 PM EST SUN DEC 25 2011 .SYNOPSIS... A QUICK MOVING UPPER LEVEL DISTURBANCE WILL BRING A BRIEF CHANCE OF RAIN THIS EVENING. LOW PRESSURE EMERGING FROM THE WESTERN GULF OF MEXICO WILL BRING A BETTER CHANCE OF SIGNIFICANT RAIN TUESDAY. DRIER WEATHER COUPLED WITH SEASONABLE TEMPERATURES IS EXPECTED FOR THE MIDDLE AND END OF THE WEEK. .NEAR TERM /THROUGH TONIGHT/... AS OF 230 PM SUNDAY...THICKER AND OPAQUE CLOUDS CONTINUE TO OVERSPREAD THE AREA WITH SE NC THE LAST TO SUCCUMB TO THE BROKEN TO OVERCAST SKY CONDITIONS. MODELS INDICATE THE PASSAGE OF A RELATIVELY WEAK SOUTHERN STREAM UPPER S/W TROUGH ACROSS THE CAROLINA COASTS THIS EVENING. HRRR FOR THE PAST SEVERAL RUNS CONTINUES TO BACK DOWN WITH PCPN COVERAGE...INTENSITY AND OVERALL CHANCES FOR LATE THIS AFTERNOON INTO THE EARLY EVENING. INITIALLY VIRGA WILL OCCUR DUE TO A RELATIVELY DRY ATMOSPHERE ACROSS THE FA. AS MOISTURE INCREASES THROUGHOUT THE ATM COLUMN...PATCHY LIGHT RAIN WILL DEVELOP UNDER 8K TO 10K CEILINGS. OVERALL...THE INLAND SC ILM CWA WILL HAVE THE BEST POTENTIAL FOR ACCUMULATING PCPN...AND IS NOW REFLECTED WITH THE LATEST POP TRENDS AND THE QPF. THE COLD FRONT EXTENDING FROM THE NORTHERN STREAM SFC LOW AND ITS ASSOCIATED UPPER S/W TROF TO TRACK ACROSS THE ILM CWA AND OFFSHORE THIS EVENING. DECENT CAA WILL FOLLOW...WITH 1K-8H THICKNESSES AND 8H TEMPS DROPPING AFTER THE CFP. THE BEST CAA WILL OCCUR LATE THIS EVENING THROUGH DAYBREAK MONDAY. THE COLD AIR WILL BE SHALLOW IN DEPTH...AS DEPICTED BY VARIOUS MODEL 1K TO 5H THICKNESS TRENDS...WHICH ONLY SLIGHTLY LOWER DURING THE PEAK OF THE CAA DURING THE OVERNIGHT HOURS. && SHORT TERM /6 AM MONDAY THROUGH 6 AM WEDNESDAY/... ...AS OF 3 PM SUNDAY...CURRENTLY A 500 MB CUT OFF LOW IS LOCATED OVER THE TEXAS PANHANDLE PLAINS...THE GLOBAL MODELS ARE LIFTING AND OPENING UP THIS CUTOFF LOW AND MOVING ITS REMNANT TROUGH AXIS TO EASTERN NORTH CAROLINA BY 06 UTC WEDNESDAY NIGHT. THE LATEST MODELS ARE SHOWING THE THE GFS AS THE FASTEST WITH THIS TROUGH AND THE NAM ...GEM AND ECMWF MODELS BEING SLOWER. AT THE SURFACE...HIGH PRESSURE WILL CONTROL THE WEATHER FOR MONDAY BUT WILL QUICKLY GIVE WAY TO A VERY DYNAMIC LOW PRESSURE SYSTEM THAT WILL SWEEP ACROSS THE AREA TUESDAY AFTERNOON AND EVENING. AT 5000 FEET THE MODELS ARE DEPICTING A LOW LEVEL JET OF 60 TO 70 KNOTS MOVING ACROSS WESTERN SOUTH CAROLINA INTO CENTRAL NORTH CAROLINA. OUR FORECAST AREA WILL BE ON THE SOUTHEASTERN FRINGES OF THE WIND MAXIMUM. THE GFS 0-2.5 BULK SHEAR SHOWS VALUES IN THE 50-55 KT RANGE AND THE NAM IS ABOUT 5 TO 10 KNOTS LOWER. THE OTHER ISSUE WILL BE THE RETURN OF THE LOW LEVEL MOISTURE...MODEL DEWPOINTS WILL STRUGGLE TO GET TO 60 DEGREES...THE MOISTURE RETURN WINDOW IS IN A VERY SMALL AND TIMING AND INTENSITY OF THIS MOISTURE SURGE WILL BE KEY IF CONVECTION IS TO TAKE PLACE. LOOKING AT THE STABILITY...THE NAM SHOWS AROUND 600 J/KG AT 18 UTC TUESDAY WHILE THE GFS COMPUTED CAPE IS INDICATING THAT THE BEST STABILITY WILL BE SHUNTED JUST OFF THE COAST. DUE TO UNCERTAINTY WITH THE TIMING AND MAX WINDS JUST TO THE WEST WILL GO WITH LIKELY SHOWERS AND ISOLATED THUNDERSTORMS FOR TUESDAY. FOR TEMPERATURES WILL STAY WITH MID 50S ON MONDAY AROUND 40 FOR LOWS MONDAY NIGHT. WITH RETURN FLOW AHEAD OF THE SURFACE LOW WILL SHOW TEMPERATURES REBOUNDING INTO THE MID TO UPPER 60S TUESDAY AND AS THE FRONT SHIFTS QUICKLY BY EXPECT LOWS TO FALL BACK TO THE LOWER TO MIDDLE 40S TUESDAY NIGHT. && && .LONG TERM /WEDNESDAY THROUGH SUNDAY/... AS OF 300 PM SUNDAY...POTENT 500 MB TROUGH EJECTING OFF TO THE NE AT THE START OF THE PERIOD WILL LEAVE IN ITS WAKE BROAD TROUGHING ACROSS THE EASTERN THIRD OF THE COUNTRY. WEAK...LOW AMPLITUDE WAVES WILL REPEATEDLY RACE OVERHEAD...BUT NO SURFACE IMPACTS WILL BE REALIZED OTHER THAN BOUTS OF CLOUD COVER. STRONGER SHORTWAVE SPAWNS A NORTHERN STREAM SYSTEM THAT WILL TRY TO DRAG A COLD FRONT THROUGH LATE FRIDAY/EARLY SATURDAY...BUT ONCE AGAIN MAY GET HUNG UP TO THE NORTH AND WASH OUT. WITH PWATS ONLY RECOVERING TO AROUND ONE-HALF INCH BY SATURDAY...EVEN IF FRONT DOES MAKE IT THROUGH THE AREA EXPECT IT TO BE DRY. WEAK CAA ON WEDNESDAY WILL BRING THE COLDEST DAY OF THE EXTENDED...WITH TEMPS A DEGREE OR TWO BELOW NORMAL FOR BOTH MAX/MIN. TEMPS REBOUND THROUGH THE REST OF THE WEEK WITH SEASONABLE NORMS RISING TO SLIGHTLY ABOVE NORMAL FOR THE WKND. MINS EACH DAY THU-SUN WILL BE IN THE MID 30S TO AROUND 40. && .AVIATION /18Z SUNDAY THROUGH FRIDAY/... AS OF 18Z...MOISTURE WILL BE ON THE INCREASE THIS AFTERNOON. LOOK FOR A CHANCE FOR PATCHY LIGHT RAIN MAINLY OVER THE SOUTHERN TERMINALS. EVEN WITH THE POSSIBLE PRECIP...CEILINGS ARE EXPECTED TO REMAIN VFR INTO THE EVENING HOURS...POSSIBLY LOWERING TO MVFR BEHIND THE FRONT TONIGHT. OVERNIGHT...WINDS WILL SLOWLY SHIFT TO THE NORTHWEST AS THE FRONT SAGS SOUTHEAST OF THE CWA...TAKING THE MOISTURE WITH IT. SCATTERED SKIES ARE EXPECTED BY THE END OF THE FORECAST PERIOD. MONDAY...NEARLY CLEAR SKIES WITH A GUSTY NORTH NORTHEAST WIND AS HIGH PRESSURE BUILDS IN. EXTENDED OUTLOOK...MODERATE CONFIDENCE FOR SHOWERS AND INTERMITTENT IFR CONDITIONS TUESDAY. VFR WEDNESDAY AND THURSDAY. && .MARINE... .NEAR TERM /THROUGH TONIGHT/... AS OF 230 PM SUNDAY...WEAK SFC BOUNDARY TO NEARLY SPLIT THE ILM COASTAL WATERS THIS AFTERNOON. WIND DIRECTIONS WILL BE THE PROBLEM CHILD PRIOR TO THE CFP THIS EVENING. HAVE GONE WITH WIND SPEEDS 10 KT OR LESS THROUGH EARLY THIS EVENING DUE TO A RELAXED SFC PG AHEAD OF THE COLD FRONT. EXPECT VARIABLE WINDS THROUGH EARLY THIS EVENING. COLD FRONT EXTENDING FROM THE SE CANADA/NE STATES DEEPENING LOW...WILL DROP SE AND SWEEP ACROSS THE ILM WATERS AND OFFSHORE DURING THIS EVENING. TIGHTENED SFC PG IN THE WAKE OF THE FRONT AND THE SHALLOW CAA SURGE TO COMBINE AND PRODUCE W TO NW WINDS REACHING SCA CRITERIA ACROSS THE ILM NC WATERS PRIOR TO MIDNIGHT. THESE WINDS ARE PROGGED TO CONTINUE AT THESE SPEEDS THROUGH DAYBREAK MONDAY. THE ILM SC WATERS ARE PROGGED TO SEE 15-20 KT WIND SPEEDS. SIGNIFICANT SEAS WILL BE DOMINATED BY AN EASTERLY 1-3 FT GROUND SWELL AT 8 TO 10 SECOND PERIODS THIS AFTERNOON INTO EARLY THIS EVENING. DUE TO THE W TO NW FETCH...SIGNIFICANT SEAS WILL BUILD TO 2 TO 4 FT...WITH THE LOCALLY PRODUCED WIND WAVES EXHIBITING 3-5 SECOND PERIODS. THIS WILL BECOME THE DOMINATE PLAYER WITHIN THE SEAS SPECTRUM OVERNIGHT. A FEW 5 FOOTERS REMAIN POSSIBLE ACROSS THE OUTER WATERS OFF CAPE FEAR OVERNIGHT. TIDE LEVELS ARE PREDICTED TO DROP TO AROUND -1.00 MLLW LATE TONIGHT. THERE WILL BE A 2 HR WINDOW SURROUNDING LOW TIDE TONIGHT THAT WILL BE SUBJECT TO THESE LOWER READINGS. LOW TIDE TO OCCUR BETWEEN 130 AM TO 200 AM MONDAY. SHORT TERM /6 AM MONDAY THROUGH 6 AM WEDNESDAY/... AS OF 3 PM SUNDAY...ON MONDAY MORNING A HIGH PRESSURE CENTER WILL SHIFT ACROSS THE AREA AND NORTHWEST FLOW WILL WEAKEN AND SEAS THAT WILL START AT 6 FT AROUND 7 AM AND THIS WILL CAUSE THE SMALL CRAFT ADVISORY SEAS NORTH OF CAPE FEAR TO FALL BELOW ADVISORY LEVELS. AS A DEVELOPING LOW PRESSURE CENTER QUICKLY MOVES BY TO THE WEST AND NORTH OF THE MARINE AREA...WINDS WILL QUICKLY VEER TO THE SOUTH BY TUESDAY MORNING. WINDS ARE EXPECTED TO REACH STRONG SMALL CRAFT VALUES AND JUST BELOW GALE FORCE BY TUESDAY AFTERNOON. SEAS WILL QUICKLY RESPONDS AND SHOULD MAX OUT AT 8 FEET TUESDAY AFTERNOON. ALSO...WITH A STRONG WEST WINDS AROUND 03 UTC WEDNESDAY WILL HAVE TO WATCH CAREFULLY FOR LOW TIDES THAT MAYBE BELOW 1 FOOT MLLW. LONG TERM/WEDNESDAY THROUGH FRIDAY/... AS OF 300 PM SUNDAY...COLD FRONT EXITING TO THE EAST TO START THE PERIOD LEAVING NW WINDS AROUND 10 KTS AND SEAS 2-4 FT EARLY WEDNESDAY...HIGHEST ACROSS THE NORTHERN WATERS. SEAS DECLINE RAPIDLY BY WEDNESDAY EVE DUE TO ADVANCE OF HIGH PRESSURE. THIS EASES THE GRADIENT AND CREATES SEAS OF ONLY 1-2 FT UNDER VARIABLE WINDS...BECOMING WEST FRIDAY AT LESS THAN 10 KTS. WINDS INCREASE FROM THE SW AHEAD OF A WEAK COLD FRONT APPROACHING FROM THE WEST FRIDAY NIGHT...BUILDING SEAS TO 2-3 FT. && .ILM WATCHES/WARNINGS/ADVISORIES... SC...NONE. NC...NONE. MARINE...SMALL CRAFT ADVISORY FROM 2 AM TO 9 AM EST MONDAY FOR AMZ250- 252. && $$ NEAR TERM...DCH SHORT TERM...HAWKINS LONG TERM...JDW AVIATION...DL
AREA FORECAST DISCUSSION
NWS NEWPORT/MOREHEAD CITY NC
202 PM EST SUN DEC 25 2011 .SYNOPSIS... A STALLED FRONTAL BOUNDARY WILL REMAIN WELL SOUTH OF NORTH CAROLINA TODAY. A DRY COLD FRONT WILL CROSS THE REGION TONIGHT. HIGH PRESSURE WILL BUILD IN FROM THE WEST MONDAY. COMPLEX LOW PRESSURE SYSTEM WILL APPROACH THE AREA FROM THE SOUTHWEST TUESDAY. THE LOW WILL PASS NORTH OF THE AREA TUESDAY EVENING WHILE SWINGING A COLD FRONT THROUGH THE REGION TUESDAY NIGHT. HIGH PRESSURE BUILDS OVER THE AREA WEDNESDAY THROUGH THE END OF NEXT WEEK. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... AS OF 1 PM SUN...MID/HIGH CLOUDS CURRENTLY STREAMING EAST ACROSS THE REGION ASSOCIATED WITH A LOW PRESSURE SYSTEM PUSHING EAST ALONG A STALLED FRONTAL BOUNDARY WELL SOUTH OF THE REGION. TEMPS LOOK TO BE IN GOOD SHAPE AS MOST INSOLATION OCCURRED PRIOR TO CURRENT CLOUD COVER...STILL EXPECTING READINGS NEAR 60 FOR LOCATIONS FROM KINSTON TO NEW BERN AND SOUTH. LIGHT SOUTHERLY WINDS WILL CONTINUE TO VEER SOUTHWEST AND INCREASE 5 TO 10 KNOTS THIS AFTERNOON IN RESPONSE TO A GRADIENT BETWEEN LOW PRESSURE SOUTH OF THE REGION AND HIGH PRESSURE BUILDING NORTH OF THE AREA. LATEST 12Z NAM/17Z RUC/15Z HRRR KEEP PRECIP OFF THE COAST LATE THIS EVENING AND OVERNIGHT SO NO SIGNIFICANT CHANGES FOR POPS/WX WITH THE EARLY AFTERNOON UPDATE. && .SHORT TERM /6 PM THIS EVENING THROUGH 6 AM MONDAY/... AS OF 1 PM SUN...FRONTAL BOUNDARY WILL REMAIN SOUTH OF THE REGION TONIGHT AS A DRY COLD FRONT PUSHES THROUGH THE AREA. WINDS WILL SHIFT WEST THEN NORTHWEST OVERNIGHT WITH SURFACE WINDS 5-7 KNOTS. MIXING WILL KEEP TEMPS IN THE MID/UPPER 30S...ALTHOUGH DRIER AIRMASS IS EXPECTED TO COVER THE REGION FROM NORTHWEST TO SOUTHEAST CURRENT DEWPOINTS RANGE IN THE LOW/MID 40S FOR PORTIONS SOUTH OF HWY 64...THUS TEMPS MAY NEED TO BE ADJUSTED UPWARDS A FEW DEGREES OVERNIGHT IN THESE AREAS. SKIES BECOME MOSTLY CLEAR BY 06Z. && .LONG TERM /MONDAY NIGHT THROUGH SUNDAY/... AS OF 200 PM SUNDAY...MONDAY NIGHT I WILL DELAY THE ONSET OF INCREASING CLOUDS UNTIL VERY LATE BASED ON THE MOVEMENT OF THE SURFACE HIGH IN THE LATEST GUIDANCE. THIS MEANS THERE WILL BE A WINDOW FOR RADIATIONAL COOLING IN THE EVENING THUS FOLLOWED THE COOLER GUIDANCE FOR LOWS. THE INCREASING CLOUDS WILL COINCIDE WITH DEVELOPING SE RETURN FLOW WHICH WILL LEAD TO THE MINIMUM TEMPERATURES OCCURRING EARLY THEN TEMPERATURES RISING LATE. THE MOST SIGNIFICANT WEATHER DURING THE LONG TERM PERIOD WILL OCCUR TUESDAY INTO TUESDAY EVENING. THE PERSISTENT SW CUT-OFF UPPER LOW WILL FINALLY EMERGE AS A DAMPENING WAVE TUESDAY DEVOLVING INTO AN OPEN WAVE AS IT CROSSES THE MID ATLANTIC TUESDAY NIGHT. DEVELOPING LOW PRESSURE WILL PASS JUST NORTH OF EASTERN NC TUESDAY EVENING AND SWING A STRONG COLD FRONT ACROSS THE REGION TUESDAY NIGHT. THIS SYSTEM WILL HAVE STRONG FORCING WITH LARGE HEIGHT FALLS PRODUCING DEEP ASCENT AND STRONG SHEAR DUE TO STRENGTHENING WIND FIELDS. THE FLOW WILL ALSO TAP THE GULF OF MEXICO AND ATLANTIC WITH PW VALUES SURGING IN EXCESS OF 1.5". THIS WILL LEAD TO THE DEVELOPMENT OF WIDESPREAD SHOWERS WITH HEAVY DOWNPOURS AHEAD OF AND ALONG THE FRONT. INSTABILITY WILL BE LIMITED AS IS USUAL THIS TIME OF YEAR BUT CAN`T RULE A FEW STRONG TO SEVERE THUNDERSTORMS. SIGNIFICANT RAINFALL IS EXPECTED WITH QPF AMOUNTS OF 0.75" TO LOCALLY 1 INCH OR MORE POSSIBLE. THE ASSOCIATED SOUTHERLY FLOW WILL PRODUCE MILD TEMPERATURES IN THE 60S. A BROAD SURFACE RIDGE OF HIGH PRESSURE IS EXPECTED ACROSS THE REGION WEDNESDAY THROUGH NEXT WEEKEND WITH DRY WEATHER AND SEASONABLE TEMPERATURES EXPECTED. THE FAST PACIFIC FLOW...HOWEVER...IS HARD TO MODEL AND THE GUIDANCE WILL HAVE TROUBLE HANDLING THE EVOLUTION OF THE LOW AMPLITUDE SHORTWAVES WHICH WILL BE RACING ACROSS THE COUNTRY THROUGH THIS PERIOD. IF ANY OF THESE OF WAVES IS ABLE TO AMPLIFY IN THE SHALLOW BROAD UPPER TROUGH FORECAST FROM THE MISSISSIPPI VALLEY TO THE APPALACHIANS MOUNTAINS...THEN A WETTER PERIOD COULD DEVELOP LATE NEXT WEEK. SOME OF THE GFS ENSEMBLE MEMBERS ARE ALREADY INDICATING SUCH A SCENARIO FOR THURSDAY NIGHT INTO FRIDAY AND AGAIN ON SUNDAY. FOR NOW WILL MAINTAIN A DRY FORECAST UNTIL A BETTER CONSENSUS DEVELOPS AMONGST THE LONG RANGE MODELS. && .AVIATION /19Z SUNDAY THROUGH FRIDAY/... SHORT TERM / THROUGH TONIGHT/... AS OF 105 PM SUN...VFR CONDITIONS EXPECTED THROUGH MON. MID AND HIGH CLOUDS WILL CONTINUE ACROSS THE AREA TODAY WITH SOUTHWEST WINDS AS LOW PRESSURE TRACKS WELL TO THE SOUTH. A STRONG DRY COLD FRONT MOVES THROUGH AFTER MIDNIGHT TONIGHT WITH WINDS BECOMING WEST THEN NORTHWEST AROUND 6-9 KT. EXPECT SURFACE WINDS AND MODERATE DEWPOINT DEPRESSIONS TO INHIBIT FOG FORMATION OR LOW STRATUS TONIGHT. VERY DRY AIRMASS IN PLACE MON AS HIGH PRESSURE EXTENDS SOUTH ACROSS THE TAF SITES. EXCELLENT MIXING WILL AID IN GUSTY NORTHWEST WINDS UPWARDS OF 20 KNOTS MON AFTERNOON. SKIES WILL BECOME MOSTLY CLEAR AROUND 06Z AND STAY MOSTLY SUNNY MON. LONG TERM /MONDAY NIGHT THROUGH FRIDAY/... AS OF 200 PM SUNDAY...SUB-VFR CONDITIONS ARE LIKELY TUESDAY INTO TUESDAY EVENING IN WIDESPREAD SHOWERS/POSSIBLE STRONG THUNDERSTORMS THAT ARE FORECAST TO OCCUR ALONG/AHEAD OF A STRONG COLD FRONT WHICH WILL CROSS THE AREA TUESDAY NIGHT. PREVAILING VFR CONDITIONS ARE THEN EXPECTED WEDNESDAY THROUGH FRIDAY AS A RELATIVELY DRY AIRMASS PERVADES THE CAROLINAS. && .MARINE... SHORT TERM /THROUGH CHRISTMAS NIGHT/... AS OF 110 PM SUN...LATEST SURFACE AND BUOY OBSERVATIONS INDICATE LIGHT SOUTHERLY WINDS AROUND 5 KNOTS. SEAS REMAIN 2 TO 3 FT AT 6 TO 8 SECONDS. WINDS WILL SHIFT SOUTHWEST AS THE DAY PROGRESSES...AND INCREASE 10 TO 15 KNOTS BY LATE THIS EVENING. WEAK LOW PRESSURE MOVING ALONG A STALLED FRONT OFF OF THE SE COAST SHOULD REMAIN WEAK AND FAR ENOUGH SOUTH SO AS NOT TO INFLUENCE LOW LEVEL FLOW TODAY. HOWEVER...SOME SPOTTY LIGHT RAIN COULD DEVELOP LATE OVER THE SOUTHERN WATERS. A STRONG DRY COLD FRONT MOVES THROUGH THE AREA TONIGHT WITH SCA CONDITIONS EXPECTED FOR ALL OF THE WATERS BY 06Z WITH W-NW WINDS INCREASING TO 20-25 KT AND SEAS BUILDING TO 5-8 FT. LONG TERM /MONDAY NIGHT THROUGH FRIDAY/... AS OF 200 PM SUNDAY...A STRONG COLD FRONT WILL APPROACH THE AREA TUESDAY AND CROSS THE WATERS TUESDAY NIGHT. STRONG SMALL CRAFT ADVISORY TO POSSIBLE GALE FORCE CONDITIONS WILL OCCUR AHEAD OF AND JUST BEHIND THE FRONT TUESDAY AND TUESDAY NIGHT. MARINERS CAN EXPECT SOUTHERLY FLOW TO 30 KT OR HIGHER TUESDAY SHIFTING TO WESTERLY THEN NORTHWESTERLY AT 30 KT OR HIGHER TUESDAY NIGHT. IN THIS FLOW SEAS WILL LIKELY REACH OR EXCEED 10 FT FOR A PERIOD TUESDAY INTO TUESDAY NIGHT. HIGHEST WINDS/SEAS ARE EXPECTED OVER THE CENTRAL WATERS. WINDS WILL DIMINISH AND SEAS WILL SUBSIDE LATE WEDNESDAY AS COLD ADVECTION WANES AND HIGH PRESSURE BUILDS OVER THE WATERS. THE BROAD HIGH WILL CONTINUE OVER THE WATERS THURSDAY THEN SHIFT OFFSHORE FRIDAY WITH WINDS 10-15 KT EXPECTED BOTH DAYS. && .MHX WATCHES/WARNINGS/ADVISORIES... NC...NONE. MARINE...SMALL CRAFT ADVISORY FROM 11 PM THIS EVENING TO 10 AM EST MONDAY FOR AMZ130-135-156-158. SMALL CRAFT ADVISORY FROM 11 PM THIS EVENING TO 11 PM EST MONDAY FOR AMZ150-152-154. && $$ SYNOPSIS...DAG NEAR TERM...DAG SHORT TERM...DAG LONG TERM...JME AVIATION...JME/DAG MARINE...JME/DAG
AREA FORECAST DISCUSSION...UPDATED
NWS NEWPORT/MOREHEAD CITY NC
109 PM EST SUN DEC 25 2011 .SYNOPSIS... A STALLED FRONTAL BOUNDARY WILL REMAIN WELL SOUTH OF NORTH CAROLINA TODAY. A DRY COLD FRONT WILL CROSS THE REGION TONIGHT. HIGH PRESSURE WILL BUILD IN FROM THE WEST MONDAY. COMPLEX LOW PRESSURE SYSTEM WILL APPROACH THE AREA FROM THE SOUTHWEST TUESDAY. THE LOW WILL PASS NORTH OF THE AREA TUESDAY EVENING WHILE SWINGING A COLD FRONT THROUGH THE REGION TUESDAY NIGHT. HIGH PRESSURE BUILDS OVER THE AREA WEDNESDAY THROUGH THE END OF NEXT WEEK. && .NEAR TERM /REST OF CHRISTMAS DAY/... AS OF 1 PM SUN...MID/HIGH CLOUDS CURRENTLY STREAMING EAST ACROSS THE REGION ASSOCIATED WITH A LOW PRESSURE SYSTEM PUSHING EAST ALONG A STALLED FRONTAL BOUNDARY WELL SOUTH OF THE REGION. TEMPS LOOK TO BE IN GOOD SHAPE AS MOST INSOLATION OCCURRED PRIOR TO CURRENT CLOUD COVER...STILL EXPECTING READINGS NEAR 60 FOR LOCATIONS FROM KINSTON TO NEW BERN AND SOUTH. LIGHT SOUTHERLY WINDS WILL CONTINUE TO VEER SOUTHWEST AND INCREASE 5 TO 10 KNOTS THIS AFTERNOON IN RESPONSE TO A GRADIENT BETWEEN LOW PRESSURE SOUTH OF THE REGION AND HIGH PRESSURE BUILDING NORTH OF THE AREA. LATEST 12Z NAM/17Z RUC/15Z HRRR KEEP PRECIP OFF THE COAST LATE THIS EVENING AND OVERNIGHT SO NO SIGNIFICANT CHANGES FOR POPS/WX WITH THE EARLY AFTERNOON UPDATE. && .SHORT TERM /TONIGHT/... AS OF 1 PM SUN...FRONTAL BOUNDARY WILL REMAIN SOUTH OF THE REGION TONIGHT AS A DRY COLD FRONT PUSHES THROUGH THE AREA. WINDS WILL SHIFT WEST THEN NORTHWEST OVERNIGHT WITH SURFACE WINDS 5-7 KNOTS. MIXING WILL KEEP TEMPS IN THE MID/UPPER 30S...ALTHOUGH DRIER AIRMASS IS EXPECTED TO COVER THE REGION FROM NORTHWEST TO SOUTHEAST CURRENT DEWPOINTS RANGE IN THE LOW/MID 40S FOR PORTIONS SOUTH OF HWY 64...THUS TEMPS MAY NEED TO BE ADJUSTED UPWARDS A FEW DEGREES OVERNIGHT IN THESE AREAS. SKIES BECOME MOSTLY CLEAR BY 06Z. && .LONG TERM /MONDAY THROUGH SATURDAY/... SHORTWAVE RIDGE TRAVERSES THE AREA MON WITH TEMPS NEAR TO SLIGHTLY BELOW NORMAL UNDER MOSTLY SUNNY SKIES. TEMPS WILL COOL RAPIDLY MON EVE AS SFC HIGH PRES MOVES OVER THE AREA. WINDS VEER SE LATE MON NIGHT AND THE DEVELOPING ONSHORE MAY CAUSE TEMPS TO RISE DURING EARLY TUE MORNING. POTENT SOUTHERN STREAM SHORTWAVE MOVING THRU THE TENN VALLEY EARLY TUE MERGES WITH A NORTHERN STREAM SYSTEM MOVING THRU THE UPPER MIDWEST. ASSOCD COLD FRONT WILL SLICE THRU EASTERN NC DURING THE LATE AFTN AND EARLY EVE. MODELS HAVE SLOWED THE FRONT A BIT BUT ARE IN GOOD AGREEMENT IN SUGGESTING A DECENT COVERAGE OF SHOWERS AHEAD OF AND IMMEDIATELY ALONG THE FRONT SO HAVE INCREASED POPS INTO THE LIKELY RANGE FOR THIS TIME PERIOD. CONTINUING TO MENTION ISOLD TSTM ALTHO INSTABILITY WILL BE MARGINAL. QPF AMOUNTS ARE EXPECTED TO BE NEAR HALF AN INCH WITH SOME AREAS POSSIBLY UP TO AN INCH. MILD TEMPS (60S) WILL BE A RESULT OF A SHARP LOW LEVEL THICKNESS RIDGE MOVING IN DURING THE AFTN BUT HAVE SHAVED OFF A FEW DEGREES GIVEN THE EXPECTED CLOUD AND PCPN COVERAGE. PRECIP WILL BE MOVING OFF THE COAST TUE NIGHT BUT MAY LINGER OVER OBX INTO EARLY WED MORN AS THE MAIN UPPER TROF AND WRAPAROUND MOISTURE PASS JUST NE OF THE AREA. RIDGING DEVELOPS AT THE SURFACE WED THROUGH FRI WITH ZONAL FLOW ALOFT. 00Z OPERATIONAL GFS RUN DEVELOPS LOW PRES OFF THE SE COAST THU AND MOVES UP THE NC COAST THU NIGHT BUT THIS IS DISCOUNTED GIVEN THE LACK OF SUPPORT FROM OTHER MODEL GUIDANCE. TEMPS WILL BE NEAR SEASONAL LEVELS...MID 50S...WED INTO THURS THEN INCREASE TO SLIGHTLY ABOVE NORMAL (LOW 60S) FRI/SAT. MIN TEMPS WILL ALSO BE NEAR SEASONAL LEVELS WITH LOWS IN THE MID-UPPER 30S WITH 40S FOR OBX. A COLD FRONT MAY APPROACH THE AREA FROM THE NW ON SAT BUT WILL NOT MENTION PRECIP AS YET AWAITING BETTER LONG RANGE MODEL CONSENSUS. && .AVIATION /18Z SUNDAY THROUGH FRIDAY/... SHORT TERM / THROUGH TONIGHT/... AS OF 105 PM SUN...VFR CONDITIONS EXPECTED THROUGH MON. MID AND HIGH CLOUDS WILL CONTINUE ACROSS THE AREA TODAY WITH SOUTHWEST WINDS AS LOW PRESSURE TRACKS WELL TO THE SOUTH. A STRONG DRY COLD FRONT MOVES THROUGH AFTER MIDNIGHT TONIGHT WITH WINDS BECOMING WEST THEN NORTHWEST AROUND 6-9 KT. EXPECT SURFACE WINDS AND MODERATE DEWPOINT DEPRESSIONS TO INHIBIT FOG FORMATION OR LOW STRATUS TONIGHT. VERY DRY AIRMASS IN PLACE MON AS HIGH PRESSURE EXTENDS SOUTH ACROSS THE TAF SITES. EXCELLENT MIXING WILL AID IN GUSTY NORTHWEST WINDS UPWARDS OF 20 KNOTS MON AFTERNOON. SKIES WILL BECOME MOSTLY CLEAR AROUND 06Z AND STAY MOSTLY SUNNY MON. LONG TERM /MONDAY THROUGH THURSDAY/... VFR CONDITIONS EXPECTED MON AS HIGH PRESSURE BUILDS ACROSS THE AREA. RETURN FLOW SETS UP LATE MON NIGHT AND STRENGTHENS TUE AS A COLD FRONT APPROACHES FROM THE WEST. MVFR/POSSIBLE IFR CONDITIONS EXPECTED TUE AFTERNOON AND EVENING AS SHOWERS WITH ISOLATED THUNDERSTORMS PASS THROUGH THE REGION. HIGH PRESSURE BUILDS BACK OVER THE REGION WED/THU WITH MAINLY VFR EXPECTED. && .MARINE... SHORT TERM /THROUGH CHRISTMAS NIGHT/... AS OF 110 PM SUN...LATEST SURFACE AND BUOY OBSERVATIONS INDICATE LIGHT SOUTHERLY WINDS AROUND 5 KNOTS. SEAS REMAIN 2 TO 3 FT AT 6 TO 8 SECONDS. WINDS WILL SHIFT SOUTHWEST AS THE DAY PROGRESSES...AND INCREASE 10 TO 15 KNOTS BY LATE THIS EVENING. WEAK LOW PRESSURE MOVING ALONG A STALLED FRONT OFF OF THE SE COAST SHOULD REMAIN WEAK AND FAR ENOUGH SOUTH SO AS NOT TO INFLUENCE LOW LEVEL FLOW TODAY. HOWEVER...SOME SPOTTY LIGHT RAIN COULD DEVELOP LATE OVER THE SOUTHERN WATERS. A STRONG DRY COLD FRONT MOVES THROUGH THE AREA TONIGHT WITH SCA CONDITIONS EXPECTED FOR ALL OF THE WATERS BY 06Z WITH W-NW WINDS INCREASING TO 20-25 KT AND SEAS BUILDING TO 5-8 FT. LONG TERM /MONDAY THROUGH THURSDAY/... SCA CONDITIONS WILL CONTINUE THRU MONDAY IN A MODERATE TO STRONG POST FRONTAL NORTH FLOW. WINDS/SEAS WILL DECREASE QUICKLY MON NIGHT AS HIGH PRES BUILDS INTO THE REGION. A VEERING FLOW WILL AGAIN INCREASE AHEAD OF A COLD FRONT ON TUESDAY WITH A RETURN TO SMALL CRAFT ADVISORY CONDITIONS EXPECTED BY MIDDAY OR SO. WINDS/SEAS PEAK LATE TUE AFTN AND EVE (WITH A FEW NEAR GALE FORCE GUSTS POSSIBLE) THEN A GRADUAL DECREASE AS LOW LEVEL CAA WANES IN THE POST FRONTAL NW/N FLOW LATE TUE NIGHT INTO WED AS BROAD HIGH PRESSURE MIGRATES EAST ACROSS THE WATERS. && .MHX WATCHES/WARNINGS/ADVISORIES... NC...NONE. MARINE...SMALL CRAFT ADVISORY FROM 11 PM THIS EVENING TO 10 AM EST MONDAY FOR AMZ130-135-156-158. SMALL CRAFT ADVISORY FROM 11 PM THIS EVENING TO 11 PM EST MONDAY FOR AMZ150-152-154. && $$ SYNOPSIS...DAG NEAR TERM...DAG SHORT TERM...DAG LONG TERM...BTC/DAG AVIATION...BTC/RF/DAG MARINE...BTC/RF/JAC/DAG
AREA FORECAST DISCUSSION
NWS WILMINGTON NC
1200 PM EST SUN DEC 25 2011 .SYNOPSIS... A QUICK MOVING UPPER LEVEL DISTURBANCE WILL BRING A BRIEF CHANCE OF RAIN LATE THIS AFTERNOON INTO THIS EVENING. LOW PRESSURE EMERGING FROM THE WESTERN GULF OF MEXICO WILL BRING A BETTER CHANCE OF SIGNIFICANT RAIN TUESDAY. DRIER WEATHER COUPLED WITH SEASONABLE TEMPERATURES IS EXPECTED FOR THE MIDDLE AND END OF THE WEEK. && .NEAR TERM /THROUGH TONIGHT/... AS OF 915 AM SUNDAY...THICKER AND OPAQUE CLOUDINESS TO OVERSPREAD THE AREA AND AID IN KEEPING MAX TEMPS FROM CLIMBING OUT OF THE 50S. THE EXCEPTION WILL BE COASTAL SE NC AND NE SC WHERE THE OPAQUE OVERCAST WILL FILL IN AROUND MIDDAY ALLOWING SOME INSOLATION TO AID MAX TEMPS REACHING INTO THE 60S. HRRR THE PAST FEW HRS HAS BACKED DOWN ON THE PCPN COVERAGE LATER THIS AFTERNOON AND EVENING. WILL TWEAK POPS SLIGHTLY LOWER ESPECIALLY ACROSS THE ILM NC COUNTIES. PREVIOUS DISCUSSION............................................... AS OF 630 AM SUNDAY...A SURFACE RIDGE EXTENDING FROM THE DELMARVA PENINSULA WEST ACROSS THE NC/VA MOUNTAINS AND INTO ARKANSAS WILL REMAIN ACROSS THE AREA THROUGH THIS EVENING. MORE IMPORTANT TO OUR WEATHER WILL BE A SHORTWAVE TROUGH CURRENTLY LOCATED ACROSS MISSISSIPPI THAT WILL MOVE EAST AND ACROSS THE CAROLINAS EARLY THIS EVENING. A SLUG OF MID-LEVEL MOISTURE FROM THE GULF OF MEXICO AND LOW-LEVEL MOISTURE FROM BOTH THE GULF AND ATLANTIC WILL GET PULLED OVERHEAD THIS AFTERNOON. WHEN COUPLED WITH THE WEAK LIFT PROVIDED BY THE TROUGH WE ARE FORECASTING RAIN CHANCES LATE THIS AFTERNOON AND EVENING...MAINLY ACROSS SOUTH CAROLINA AND AFTER 2-3 PM. THERE WILL BE A SHORT WINDOW OF OPPORTUNITY FOR RAIN TO FALL...AND GIVEN THE MEAGER LIFT ADVERTISED ON THE LATEST GFS/NAM RUNS OUR ACTUAL RAINFALL FORECASTS ARE FOR 0.05 INCHES OR LESS. AS THE SHORTWAVE TROUGH EXITS THE COAST THIS EVENING...HIGH PRESSURE OVER THE CENTRAL PLAINS STATES WILL BUILD EAST AND INTO THE CAROLINAS. THIS WILL CREATE A SURGE OF COLD NORTHWESTERLY WINDS AFTER MIDNIGHT THAT WILL CONTINUE THROUGH DAYBREAK MONDAY. HIGHS TODAY SHOULD RANGE FROM 55-60...WARMEST AT THE COAST. LOWS TONIGHT SHOULD FALL INTO THE UPPER 30S MOST LOCATIONS. NOTE: DUE TO COMPUTER PROBLEMS AT NCEP THE 00Z NAM MOS PRODUCTS WERE NOT PRODUCED. && .SHORT TERM /MONDAY THROUGH TUESDAY NIGHT/... AS OF 3 AM SUNDAY...FOCUS FOR THE SHORT TERM WILL BE UPPER SYSTEM TRACKING NORTHEAST FROM TX MON NIGHT. AHEAD OF THE OPENING WAVE VERY DRY HIGH PRESSURE BUILDING IN MON WILL SHIFT OFF THE NC/VA COAST MON NIGHT. ANTICIPATE VERY LITTLE IN THE WAY OF CLOUDS MON LET ALON PRECIP. COLD ADVECTION WILL BE ENDING MON MORNING BUT COOLER AIR WILL ALREADY BE IN PLACE ENSURING HIGHS RIGHT AROUND CLIMO. RETURN FLOW DEVELOPING LATE MON NIGHT WILL START TEMPS/DEWPOINTS ON A GRADUAL UPWARD TREND BEFORE DAYBREAK. WEAK COASTAL TROF/WARM FRONT MOVES ONSHORE FAIRLY EARLY TUE HELPING BREAK VERY WEAK WEDGE. STRONG WARM ADVECTION RAPIDLY INCREASES LOW LEVEL MOISTURE WHILE STRONG SOUTH TO SOUTHWEST MID LEVEL FLOW INCREASES MOISTURE ABOVE 900 MB. HAVE HELD ONTO LIKELY POP FOR TUE GIVEN THAT THERE IS STILL SOME QUESTION WITH RESPECT TO TIMING. WHILE GOOD AGREEMENT BETWEEN THE GUIDANCE CONTINUES...NEARLY ALL OF THE 00Z SOLUTIONS ARE SLOWER BY ABOUT 6 HOURS OR SO. NOT ONLY WOULD SLOWER EVOLUTION DELAY PRECIP BUT IT WOULD AFFECT TEMP FORECAST AND CREATE A LARGER WINDOW FOR CONVECTION. INCREASING INSTABILITY WITHIN THE WARM SECTOR...DEEP MOISTURE...STRONG DIVERGENCE ALOFT...AND STRONG LOW LEVEL JET DO POINT TO THE POTENTIAL FOR SOME ISOLATED STRONG CONVECTION...ESPECIALLY IF THE SLOWER SOLUTION COMES TO PASS. RAINFALL AMOUNTS IN THE HALF INCH RANGE ARE EXPECTED THOUGH ISOLATED HIGHER AMOUNTS ARE CERTAINLY POSSIBLE. COLD FRONT MOVES ACROSS THE AREA LATE TUE FOLLOWED BY A BRIEF PERIOD OF WEAK COLD ADVECTION. BOUNDARY LAYER MIXING AND LACK OF SIGNIFICANT COLD ADVECTION KEEPS TUE NIGHT LOWS NEAR TO SLIGHTLY ABOVE CLIMO...WITH COOLEST AREAS TO THE WEST. && .LONG TERM /WEDNESDAY THROUGH SATURDAY/... AS OF 3 AM SUNDAY...AS 5H TROF EXITS NORTHEAST WED MORNING THE PATTERN ALOFT WILL BECOME MORE PROGRESSIVE. ZONAL PATTERN WILL REMAIN IN PLACE THROUGH THE PERIOD...THOUGH SOME WEAK RIDGING DOES START TO CREEP IN NEXT WEEKEND. A FEW WEAK MOISTURE STARVED WAVE WILL PASS JUST NORTH OF THE AREA...BUT A FEW CLOUDS IS ALL THAT CAN BE EXPECTED. TEMPERATURES NEAR CLIMO FOR MUCH OF THE PERIOD WILL CREEP ABOVE CLIMO LATE IN THE PERIOD. IT IS WORTH NOTING THE 00Z GFS IS NOW SHOWING A WEAK WAVE OFF THE SOUTHEAST COAST THU WHICH MOVES NORTH INTO FRI. ONCE THE LOW REACHES HATTERAS DIVERGENCE ALOFT...ASSOCIATED WITH SHORTWAVE DIGGING OVER THE GREAT LAKES...HELPS STRENGTHEN THE LOW. ONLY THE 00Z GFS DEPICTS THIS SOLUTION AND IT SEEMS OVER AMPLIFIED. WILL IGNORE IT FOR NOW. && .AVIATION /18Z SUNDAY THROUGH FRIDAY/... AS OF 18Z...MOISTURE WILL BE ON THE INCREASE THIS AFTERNOON. LOOK FOR A CHANCE FOR PATCHY LIGHT RAIN MAINLY OVER THE SOUTHERN TERMINALS. EVEN WITH THE POSSIBLE PRECIP...CEILINGS ARE EXPECTED TO REMAIN VFR INTO THE EVENING HOURS...POSSIBLY LOWERING TO MVFR BEHIND THE FRONT TONIGHT. OVERNIGHT...WINDS WILL SLOWLY SHIFT TO THE NORTHWEST AS THE FRONT SAGS SOUTHEAST OF THE CWA...TAKING THE MOISTURE WITH IT. SCATTERED SKIES ARE EXPECTED BY THE END OF THE FORECAST PERIOD. MONDAY...NEARLY CLEAR SKIES WITH A GUSTY NORTH NORTHEAST WIND AS HIGH PRESSURE BUILDS IN. EXTENDED OUTLOOK...MODERATE CONFIDENCE FOR SHOWERS AND INTERMITTENT IFR CONDITIONS TUESDAY. VFR WEDNESDAY AND THURSDAY. && .MARINE... NEAR TERM /THROUGH TONIGHT/... AS OF 915 AM SUNDAY...SFC BOUNDARY TO NEARLY SPLIT THE ILM COASTAL WATERS TODAY. WIND DIRECTIONS WILL BE THE PROBLEM CHILD WITH WIND SPEEDS 10 KT OR LESS DUE TO A RELAXED SFC PG. WILL INDICATE A VARIABLE WIND DIRECTION THIS AFTERNOON. COLD FRONT DROPS SE AND SWEEPS ACROSS THE ILM WATERS AND OFFSHORE THIS EVENING. TIGHTENED SFC PG IN THE WAKE OF THE FRONT AND CAA SURGE TO PUSH W TO NW WINDS TO SCA CRITERIA FOR THE ILM NC WATERS AROUND MIDNIGHT...AND CONTINUING AT THESE SPEEDS THROUGH DAYBREAK MONDAY. THE ILM SC WATERS WILL SEE 15-20 KT SPEEDS. SIGNIFICANT SEAS WILL BE DOMINATED BY AN EASTERLY 1-3 FT SWELL AT 7 TO 9 SECOND PERIODS TODAY. DUE TO THE NW FETCH...EXPECT 2 TO 4 FT LOCALLY PRODUCED WIND WAVES AT 3-5 SECOND PERIODS BECOMING THE DOMINATE PLAYER AFTER THE COLD FRONT PUSHES THIS EVENING. PREVIOUS DISCUSSION............................................... AS OF 630 AM SUNDAY...A RIDGE OF HIGH PRESSURE ACROSS SOUTHERN VIRGINIA WILL REMAIN JUST TO OUR NORTH THROUGH EARLY THIS EVENING. THIS SHOULD MAINTAIN LIGHT WINDS ACROSS THE COASTAL WATERS. AN UPPER LEVEL DISTURBANCE COULD BRING A PERIOD OF LIGHT RAIN LATE THIS AFTERNOON INTO EARLY THIS EVENING ACROSS MAINLY THE SOUTH CAROLINA WATERS. ANY RAIN SHOULD SHIFT OFFSHORE BEFORE MIDNIGHT. HIGH PRESSURE OVER THE CENTRAL PLAINS WILL SURGE EAST LATE TONIGHT BRINGING INCREASING NORTHWESTERLY WINDS WHICH COULD REACH 25 KNOTS ACROSS THE NORTH CAROLINA WATERS. WE ARE THEREFORE HOISTING A SMALL CRAFT ADVISORY NORTH OF LITTLE RIVER INLET BEGINNING AT 2 AM MONDAY. SEAS ARE CURRENTLY 3 FT AT THE FRYING PAN SHOALS BUOY AND 3 FT AT THE NEARSHORE WRIGHTSVILLE BEACH BUOY. SINCE WINDS ARE FAIRLY LIGHT A CHECK OF THE SPECTRAL WAVE PLOT CONFIRMS WE ARE MAINLY EXPERIENCING AN 8-SECOND SWELL. SEAS SHOULD CHANGE LITTLE THROUGH THIS EVENING...BUT AFTER MIDNIGHT INCREASING OFFSHORE WINDS WILL DEVELOP A SHORT PERIOD (3-5 SECOND) CHOP LATE. SHORT TERM /MONDAY THROUGH TUESDAY NIGHT/... AS OF 3 AM SUNDAY...BRIEF NORTHERLY SURGE WILL BE WEAKENING MON MORNING BUT MAY REQUIRE HEADLINES FOR THE FIRST FEW HOURS OF THE PERIOD. WINDS QUICKLY DROP BELOW 15 KT AND VEER TO NORTH-NORTHEAST MON INTO MON NIGHT AS HIGH PRESSURE SHIFTS OFF THE NC/VA COAST. WARM FRONT MOVES ONSHORE LATE MON NIGHT WITH WINDS BECOMING ONSHORE AND INCREASING AS GRADIENT TIGHTENS. COOLER NEARSHORE WATER TEMPS WILL LIMIT GUSTINESS BUT COULD ALSO RESULT IN SOME SEA FOG. HEADLINES WILL LIKELY BE NEEDED TUE AS BOTH WINDS AND SEAS ARE EXPECTED TO EXCEED THRESHOLDS AS DEEPENING LOW PRESSURE MOVES ACROSS THE CAROLINAS. STRONG COLD FRONT CROSSES THE WATERS TUE NIGHT WITH STRONG SOUTHWEST FLOW IN ITS WAKE BECOMING WESTERLY. NOT A LOT OF COLD ADVECTION BEHIND THE FRONT SO WINDS MAY NOT BE VERY GUSTY...BUT PINCHED GRADIENT WILL KEEP WINDS 15 TO 20 KT INTO WED MORNING. 2 TO 3 FT SEAS MON AND MON NIGHT WILL BUILD TO 6 TO 9 FT BEFORE COLD FRONT SWEEPS ACROSS THE WATERS TUE NIGHT. SEAS WILL SLOWLY FALL TUE NIGHT AS WINDS BECOME WEST AND THEN NORTHWEST. LONG TERM /WEDNESDAY THROUGH THURSDAY/... AS OF 3 AM SUNDAY...LIGHT WEST TO NORTHWEST FLOW WED AS HIGH PRESSURE MOVES MOVES EAST ACROSS THE GULF COAST. WINDS BECOME LIGHT AND VARIABLE LATE WED NIGHT AS RIDGE AXIS ELONGATES AND SHIFTS SOUTHEAST OF THE AREA. LIGHT RETURN FLOW DEVELOPS BY THU BUT GRADIENT REMAINS WEAK. SPEEDS THROUGH THE PERIOD WILL GENERALLY BE 10 KT OR LESS WITH SEAS 2 TO 3 FT. && .ILM WATCHES/WARNINGS/ADVISORIES... SC...NONE. NC...NONE. MARINE...SMALL CRAFT ADVISORY FROM 2 AM TO 9 AM EST MONDAY FOR AMZ250- 252. && $$ NEAR TERM...DCH/TRA SHORT TERM...III LONG TERM...III AVIATION...43
AREA FORECAST DISCUSSION...UPDATED
NWS NEWPORT/MOREHEAD CITY NC
1053 AM EST SUN DEC 25 2011 .SYNOPSIS... A STALLED FRONTAL BOUNDARY WILL REMAIN WELL SOUTH OF NORTH CAROLINA TODAY. A DRY COLD FRONT WILL CROSS THE REGION TONIGHT. HIGH PRESSURE WILL BUILD IN FROM THE WEST MONDAY. COMPLEX LOW PRESSURE SYSTEM WILL APPROACH THE AREA FROM THE SOUTHWEST TUESDAY. THE LOW WILL PASS NORTH OF THE AREA TUESDAY EVENING WHILE SWINGING A COLD FRONT THROUGH THE REGION TUESDAY NIGHT. HIGH PRESSURE BUILDS OVER THE AREA WEDNESDAY THROUGH THE END OF NEXT WEEK. && .NEAR TERM /REST OF CHRISTMAS DAY/... AS OF 1040 AM SUN...MID/HIGH CLOUDS CURRENTLY STREAMING EAST ACROSS THE REGION ASSOCIATED WITH A LOW PRESSURE SYSTEM PUSHING EAST ALONG A STALLED FRONTAL BOUNDARY WELL SOUTH OF THE REGION. BUMPED TEMPS DOWN A FEW DEGREES GIVEN EXPECTED CLOUD COVER...TO LOWER 60S FOR THE SOUTHERN COASTAL PLAINS. TEMPS ARE RECOVERING QUICKLY LATE THIS MORNING WITH OAJ/EWN ALREADY 52 DEGREES. LIGHT SOUTHERLY WINDS WILL VEER SOUTHWEST AND INCREASE 5 TO 10 KNOTS THIS AFTERNOON IN RESPONSE TO A GRADIENT BETWEEN LOW PRESSURE SOUTH OF THE REGION AND HIGH PRESSURE BUILDING NORTH OF THE AREA. LATEST 12Z NAM/14Z RUC KEEP PRECIP OFF THE COAST LATE THIS EVENING AND OVERNIGHT SO NO SIGNIFICANT CHANGES FOR POPS/WX WITH THIS UPDATE. && .SHORT TERM /TONIGHT/... AS OF 645 AM SUNDAY...MID LVL SHTWV PASSES TO THE N BRINGING A DRY COLD FRONT THROUGH THROUGH THE AREA WITH BRISK W-NW WINDS AND CLEARING SKIES. EXPECT MINS TONIGHT WILL RANGE FROM THE MID AND UPR 30S INLAND TO THE LWR 40S ON THE COAST WITH STRONG COLD AIR ADVECTION BEHIND THE FRONT && .LONG TERM /MONDAY THROUGH SATURDAY/... SHORTWAVE RIDGE TRAVERSES THE AREA MON WITH TEMPS NEAR TO SLIGHTLY BELOW NORMAL UNDER MOSTLY SUNNY SKIES. TEMPS WILL COOL RAPIDLY MON EVE AS SFC HIGH PRES MOVES OVER THE AREA. WINDS VEER SE LATE MON NIGHT AND THE DEVELOPING ONSHORE MAY CAUSE TEMPS TO RISE DURING EARLY TUE MORNING. POTENT SOUTHERN STREAM SHORTWAVE MOVING THRU THE TENN VALLEY EARLY TUE MERGES WITH A NORTHERN STREAM SYSTEM MOVING THRU THE UPPER MIDWEST. ASSOCD COLD FRONT WILL SLICE THRU EASTERN NC DURING THE LATE AFTN AND EARLY EVE. MODELS HAVE SLOWED THE FRONT A BIT BUT ARE IN GOOD AGREEMENT IN SUGGESTING A DECENT COVERAGE OF SHOWERS AHEAD OF AND IMMEDIATELY ALONG THE FRONT SO HAVE INCREASED POPS INTO THE LIKELY RANGE FOR THIS TIME PERIOD. CONTINUING TO MENTION ISOLD TSTM ALTHO INSTABILITY WILL BE MARGINAL. QPF AMOUNTS ARE EXPECTED TO BE NEAR HALF AN INCH WITH SOME AREAS POSSIBLY UP TO AN INCH. MILD TEMPS (60S) WILL BE A RESULT OF A SHARP LOW LEVEL THICKNESS RIDGE MOVING IN DURING THE AFTN BUT HAVE SHAVED OFF A FEW DEGREES GIVEN THE EXPECTED CLOUD AND PCPN COVERAGE. PRECIP WILL BE MOVING OFF THE COAST TUE NIGHT BUT MAY LINGER OVER OBX INTO EARLY WED MORN AS THE MAIN UPPER TROF AND WRAPAROUND MOISTURE PASS JUST NE OF THE AREA. RIDGING DEVELOPS AT THE SURFACE WED THROUGH FRI WITH ZONAL FLOW ALOFT. 00Z OPERATIONAL GFS RUN DEVELOPS LOW PRES OFF THE SE COAST THU AND MOVES UP THE NC COAST THU NIGHT BUT THIS IS DISCOUNTED GIVEN THE LACK OF SUPPORT FROM OTHER MODEL GUIDANCE. TEMPS WILL BE NEAR SEASONAL LEVELS...MID 50S...WED INTO THURS THEN INCREASE TO SLIGHTLY ABOVE NORMAL (LOW 60S) FRI/SAT. MIN TEMPS WILL ALSO BE NEAR SEASONAL LEVELS WITH LOWS IN THE MID-UPPER 30S WITH 40S FOR OBX. A COLD FRONT MAY APPROACH THE AREA FROM THE NW ON SAT BUT WILL NOT MENTION PRECIP AS YET AWAITING BETTER LONG RANGE MODEL CONSENSUS. && .AVIATION /16Z SUNDAY THROUGH THURSDAY/... SHORT TERM / THROUGH TONIGHT/... AS OF 645 AM SUNDAY...VFR CONDITIONS EXPECTED THROUGH TODAY. MID AND HIGH CLOUDS INCREASE ACROSS THE AREA TODAY WITH WINDS BECOMING SOUTHWEST AS LOW PRESSURE TRACKS WELL TO THE SOUTH. A STRONG DRY COLD FRONT MOVES THROUGH AFTER MIDNIGHT TONIGHT WITH WINDS BECOMING WEST THEN NORTHWEST AROUND 10 KT. THUS EXPECT SURFACE WINDS AND MODERATE DEWPOINT DEPRESSIONS TO INHIBIT FOG FORMATION OR LOW STRATUS. LONG TERM /MONDAY THROUGH THURSDAY/... VFR CONDITIONS EXPECTED MON AS HIGH PRESSURE BUILDS ACROSS THE AREA. RETURN FLOW SETS UP LATE MON NIGHT AND STRENGTHENS TUE AS A COLD FRONT APPROACHES FROM THE WEST. MVFR/POSSIBLE IFR CONDITIONS EXPECTED TUE AFTERNOON AND EVENING AS SHOWERS WITH ISOLATED THUNDERSTORMS PASS THROUGH THE REGION. HIGH PRESSURE BUILDS BACK OVER THE REGION WED/THU WITH MAINLY VFR EXPECTED. && .MARINE... SHORT TERM /THROUGH CHRISTMAS NIGHT/... AS OF 1045 AM SUN...LATEST SURFACE AND BUOY OBSERVATIONS INDICATE LIGHT WINDS AROUND 5 KNOTS...WITH AN OFFSHORE SHIP REPORT OF 10 KNOTS OUT OF THE NORTH FROM WDD3825. SEAS REMAIN LONG PERIOD SWELLS 2 TO 3 FT OFF DUCK TO OFF ONSLOW BAY. WINDS WILL SHIFT TO SOUTH THEN SOUTHWEST AS THE DAY PROGRESSES...AND INCREASE 10 TO 15 KNOTS BY LATE THIS EVENING. WEAK LOW PRESSURE MOVING ALONG A STALLED FRONT OFF OF THE SE COAST SHOULD REMAIN WEAK AND FAR ENOUGH SOUTH SO AS NOT TO INFLUENCE LOW LEVEL FLOW TODAY. HOWEVER...SOME SPOTTY LIGHT RAIN COULD DEVELOP LATE OVER THE SOUTHERN WATERS. A STRONG DRY COLD FRONT MOVES THROUGH THE AREA TONIGHT WITH SCA CONDITIONS EXPECTED FOR ALL OF THE WATERS BY 06Z WITH W-NW WINDS INCREASING TO 20-25 KT AND SEAS BUILDING TO 5-7 FT. LONG TERM /MONDAY THROUGH THURSDAY/... SCA CONDITIONS WILL CONTINUE THRU MONDAY IN A MODERATE TO STRONG POST FRONTAL NORTH FLOW. WINDS/SEAS WILL DECREASE QUICKLY MON NIGHT AS HIGH PRES BUILDS INTO THE REGION. A VEERING FLOW WILL AGAIN INCREASE AHEAD OF A COLD FRONT ON TUESDAY WITH A RETURN TO SMALL CRAFT ADVISORY CONDITIONS EXPECTED BY MIDDAY OR SO. WINDS/SEAS PEAK LATE TUE AFTN AND EVE (WITH A FEW NEAR GALE FORCE GUSTS POSSIBLE) THEN A GRADUAL DECREASE AS LOW LEVEL CAA WANES IN THE POST FRONTAL NW/N FLOW LATE TUE NIGHT INTO WED AS BROAD HIGH PRESSURE MIGRATES EAST ACROSS THE WATERS. && .MHX WATCHES/WARNINGS/ADVISORIES... NC...NONE. MARINE...SMALL CRAFT ADVISORY FROM 11 PM THIS EVENING TO 10 AM EST MONDAY FOR AMZ130-135-156-158. SMALL CRAFT ADVISORY FROM 11 PM THIS EVENING TO 11 PM EST MONDAY FOR AMZ150-152-154. && $$ SYNOPSIS...DAG NEAR TERM...DAG SHORT TERM...JAC LONG TERM...BTC/DAG AVIATION...JAC/BTC/RF/DAG MARINE...JAC/BTC/RF/DAG
AREA FORECAST DISCUSSION
NWS WILMINGTON NC
915 AM EST SUN DEC 25 2011 .SYNOPSIS... A QUICK MOVING UPPER LEVEL DISTURBANCE WILL BRING A BRIEF CHANCE OF RAIN LATE THIS AFTERNOON INTO THIS EVENING. LOW PRESSURE EMERGING FROM THE WESTERN GULF OF MEXICO WILL BRING A BETTER CHANCE OF SIGNIFICANT RAIN TUESDAY. DRIER WEATHER COUPLED WITH SEASONABLE TEMPERATURES IS EXPECTED FOR THE MIDDLE AND END OF THE WEEK. && .NEAR TERM /THROUGH TONIGHT/... AS OF 915 AM SUNDAY...THICKER AND OPAQUE CLOUDINESS TO OVERSPREAD THE AREA AND AID IN KEEPING MAX TEMPS FROM CLIMBING OUT OF THE 50S. THE EXCEPTION WILL BE COASTAL SE NC AND NE SC WHERE THE OPAQUE OVERCAST WILL FILL IN AROUND MIDDAY ALLOWING SOME INSOLATION TO AID MAX TEMPS REACHING INTO THE 60S. HRRR THE PAST FEW HRS HAS BACKED DOWN ON THE PCPN COVERAGE LATER THIS AFTERNOON AND EVENING. WILL TWEAK POPS SLIGHTLY LOWER ESPECIALLY ACROSS THE ILM NC COUNTIES. PREVIOUS DISCUSSION............................................... AS OF 630 AM SUNDAY...A SURFACE RIDGE EXTENDING FROM THE DELMARVA PENINSULA WEST ACROSS THE NC/VA MOUNTAINS AND INTO ARKANSAS WILL REMAIN ACROSS THE AREA THROUGH THIS EVENING. MORE IMPORTANT TO OUR WEATHER WILL BE A SHORTWAVE TROUGH CURRENTLY LOCATED ACROSS MISSISSIPPI THAT WILL MOVE EAST AND ACROSS THE CAROLINAS EARLY THIS EVENING. A SLUG OF MID-LEVEL MOISTURE FROM THE GULF OF MEXICO AND LOW-LEVEL MOISTURE FROM BOTH THE GULF AND ATLANTIC WILL GET PULLED OVERHEAD THIS AFTERNOON. WHEN COUPLED WITH THE WEAK LIFT PROVIDED BY THE TROUGH WE ARE FORECASTING RAIN CHANCES LATE THIS AFTERNOON AND EVENING...MAINLY ACROSS SOUTH CAROLINA AND AFTER 2-3 PM. THERE WILL BE A SHORT WINDOW OF OPPORTUNITY FOR RAIN TO FALL...AND GIVEN THE MEAGER LIFT ADVERTISED ON THE LATEST GFS/NAM RUNS OUR ACTUAL RAINFALL FORECASTS ARE FOR 0.05 INCHES OR LESS. AS THE SHORTWAVE TROUGH EXITS THE COAST THIS EVENING...HIGH PRESSURE OVER THE CENTRAL PLAINS STATES WILL BUILD EAST AND INTO THE CAROLINAS. THIS WILL CREATE A SURGE OF COLD NORTHWESTERLY WINDS AFTER MIDNIGHT THAT WILL CONTINUE THROUGH DAYBREAK MONDAY. HIGHS TODAY SHOULD RANGE FROM 55-60...WARMEST AT THE COAST. LOWS TONIGHT SHOULD FALL INTO THE UPPER 30S MOST LOCATIONS. NOTE: DUE TO COMPUTER PROBLEMS AT NCEP THE 00Z NAM MOS PRODUCTS WERE NOT PRODUCED. && .SHORT TERM /MONDAY THROUGH TUESDAY NIGHT/... AS OF 3 AM SUNDAY...FOCUS FOR THE SHORT TERM WILL BE UPPER SYSTEM TRACKING NORTHEAST FROM TX MON NIGHT. AHEAD OF THE OPENING WAVE VERY DRY HIGH PRESSURE BUILDING IN MON WILL SHIFT OFF THE NC/VA COAST MON NIGHT. ANTICIPATE VERY LITTLE IN THE WAY OF CLOUDS MON LET ALON PRECIP. COLD ADVECTION WILL BE ENDING MON MORNING BUT COOLER AIR WILL ALREADY BE IN PLACE ENSURING HIGHS RIGHT AROUND CLIMO. RETURN FLOW DEVELOPING LATE MON NIGHT WILL START TEMPS/DEWPOINTS ON A GRADUAL UPWARD TREND BEFORE DAYBREAK. WEAK COASTAL TROF/WARM FRONT MOVES ONSHORE FAIRLY EARLY TUE HELPING BREAK VERY WEAK WEDGE. STRONG WARM ADVECTION RAPIDLY INCREASES LOW LEVEL MOISTURE WHILE STRONG SOUTH TO SOUTHWEST MID LEVEL FLOW INCREASES MOISTURE ABOVE 900 MB. HAVE HELD ONTO LIKELY POP FOR TUE GIVEN THAT THERE IS STILL SOME QUESTION WITH RESPECT TO TIMING. WHILE GOOD AGREEMENT BETWEEN THE GUIDANCE CONTINUES...NEARLY ALL OF THE 00Z SOLUTIONS ARE SLOWER BY ABOUT 6 HOURS OR SO. NOT ONLY WOULD SLOWER EVOLUTION DELAY PRECIP BUT IT WOULD AFFECT TEMP FORECAST AND CREATE A LARGER WINDOW FOR CONVECTION. INCREASING INSTABILITY WITHIN THE WARM SECTOR...DEEP MOISTURE...STRONG DIVERGENCE ALOFT...AND STRONG LOW LEVEL JET DO POINT TO THE POTENTIAL FOR SOME ISOLATED STRONG CONVECTION...ESPECIALLY IF THE SLOWER SOLUTION COMES TO PASS. RAINFALL AMOUNTS IN THE HALF INCH RANGE ARE EXPECTED THOUGH ISOLATED HIGHER AMOUNTS ARE CERTAINLY POSSIBLE. COLD FRONT MOVES ACROSS THE AREA LATE TUE FOLLOWED BY A BRIEF PERIOD OF WEAK COLD ADVECTION. BOUNDARY LAYER MIXING AND LACK OF SIGNIFICANT COLD ADVECTION KEEPS TUE NIGHT LOWS NEAR TO SLIGHTLY ABOVE CLIMO...WITH COOLEST AREAS TO THE WEST. && .LONG TERM /WEDNESDAY THROUGH SATURDAY/... AS OF 3 AM SUNDAY...AS 5H TROF EXITS NORTHEAST WED MORNING THE PATTERN ALOFT WILL BECOME MORE PROGRESSIVE. ZONAL PATTERN WILL REMAIN IN PLACE THROUGH THE PERIOD...THOUGH SOME WEAK RIDGING DOES START TO CREEP IN NEXT WEEKEND. A FEW WEAK MOISTURE STARVED WAVE WILL PASS JUST NORTH OF THE AREA...BUT A FEW CLOUDS IS ALL THAT CAN BE EXPECTED. TEMPERATURES NEAR CLIMO FOR MUCH OF THE PERIOD WILL CREEP ABOVE CLIMO LATE IN THE PERIOD. IT IS WORTH NOTING THE 00Z GFS IS NOW SHOWING A WEAK WAVE OFF THE SOUTHEAST COAST THU WHICH MOVES NORTH INTO FRI. ONCE THE LOW REACHES HATTERAS DIVERGENCE ALOFT...ASSOCIATED WITH SHORTWAVE DIGGING OVER THE GREAT LAKES...HELPS STRENGTHEN THE LOW. ONLY THE 00Z GFS DEPICTS THIS SOLUTION AND IT SEEMS OVER AMPLIFIED. WILL IGNORE IT FOR NOW. && .AVIATION /12Z SUNDAY THROUGH THURSDAY/... AS OF 12Z...MOISTURE WILL BE ON THE INCREASE TODAY. LOOK FOR THICKENING HIGH CLOUDS THIS MORNING...WITH A CHANCE FOR PATCHY LIGHT RAIN MAINLY OVER THE SOUTHERN TERMINALS. EVEN WITH THE POSSIBLE PRECIP...CEILINGS ARE EXPECTED TO REMAIN VFR INTO THE EVENING HOURS. POSSIBLY LOWERING TO MVFR BEHIND THE FRONT TONIGHT. OVERNIGHT...WINDS WILL SLOWLY SHIFT TO THE NORTHWEST AS THE FRONT SAGS SOUTHEAST OF THE CWA...TAKING THE MOISTURE WITH IT. SCATTERED SKIES ARE EXPECTED BY THE END OF THE FORECAST PERIOD. EXTENDED OUTLOOK...ANTICIPATE VFR THROUGH MONDAY. POSSIBLE SHOWERS AND IFR CONDITIONS TUESDAY. VFR WEDNESDAY AND THURSDAY. && .MARINE... NEAR TERM /THROUGH TONIGHT/... AS OF 915 AM SUNDAY...SFC BOUNDARY TO NEARLY SPLIT THE ILM COASTAL WATERS TODAY. WIND DIRECTIONS WILL BE THE PROBLEM CHILD WITH WIND SPEEDS 10 KT OR LESS DUE TO A RELAXED SFC PG. WILL INDICATE A VARIABLE WIND DIRECTION THIS AFTERNOON. COLD FRONT DROPS SE AND SWEEPS ACROSS THE ILM WATERS AND OFFSHORE THIS EVENING. TIGHTENED SFC PG IN THE WAKE OF THE FRONT AND CAA SURGE TO PUSH W TO NW WINDS TO SCA CRITERIA FOR THE ILM NC WATERS AROUND MIDNIGHT...AND CONTINUING AT THESE SPEEDS THROUGH DAYBREAK MONDAY. THE ILM SC WATERS WILL SEE 15-20 KT SPEEDS. SIGNIFICANT SEAS WILL BE DOMINATED BY AN EASTERLY 1-3 FT SWELL AT 7 TO 9 SECOND PERIODS TODAY. DUE TO THE NW FETCH...EXPECT 2 TO 4 FT LOCALLY PRODUCED WIND WAVES AT 3-5 SECOND PERIODS BECOMING THE DOMINATE PLAYER AFTER THE COLD FRONT PUSHES THIS EVENING. PREVIOUS DISCUSSION............................................... AS OF 630 AM SUNDAY...A RIDGE OF HIGH PRESSURE ACROSS SOUTHERN VIRGINIA WILL REMAIN JUST TO OUR NORTH THROUGH EARLY THIS EVENING. THIS SHOULD MAINTAIN LIGHT WINDS ACROSS THE COASTAL WATERS. AN UPPER LEVEL DISTURBANCE COULD BRING A PERIOD OF LIGHT RAIN LATE THIS AFTERNOON INTO EARLY THIS EVENING ACROSS MAINLY THE SOUTH CAROLINA WATERS. ANY RAIN SHOULD SHIFT OFFSHORE BEFORE MIDNIGHT. HIGH PRESSURE OVER THE CENTRAL PLAINS WILL SURGE EAST LATE TONIGHT BRINGING INCREASING NORTHWESTERLY WINDS WHICH COULD REACH 25 KNOTS ACROSS THE NORTH CAROLINA WATERS. WE ARE THEREFORE HOISTING A SMALL CRAFT ADVISORY NORTH OF LITTLE RIVER INLET BEGINNING AT 2 AM MONDAY. SEAS ARE CURRENTLY 3 FT AT THE FRYING PAN SHOALS BUOY AND 3 FT AT THE NEARSHORE WRIGHTSVILLE BEACH BUOY. SINCE WINDS ARE FAIRLY LIGHT A CHECK OF THE SPECTRAL WAVE PLOT CONFIRMS WE ARE MAINLY EXPERIENCING AN 8-SECOND SWELL. SEAS SHOULD CHANGE LITTLE THROUGH THIS EVENING...BUT AFTER MIDNIGHT INCREASING OFFSHORE WINDS WILL DEVELOP A SHORT PERIOD (3-5 SECOND) CHOP LATE. SHORT TERM /MONDAY THROUGH TUESDAY NIGHT/... AS OF 3 AM SUNDAY...BRIEF NORTHERLY SURGE WILL BE WEAKENING MON MORNING BUT MAY REQUIRE HEADLINES FOR THE FIRST FEW HOURS OF THE PERIOD. WINDS QUICKLY DROP BELOW 15 KT AND VEER TO NORTH-NORTHEAST MON INTO MON NIGHT AS HIGH PRESSURE SHIFTS OFF THE NC/VA COAST. WARM FRONT MOVES ONSHORE LATE MON NIGHT WITH WINDS BECOMING ONSHORE AND INCREASING AS GRADIENT TIGHTENS. COOLER NEARSHORE WATER TEMPS WILL LIMIT GUSTINESS BUT COULD ALSO RESULT IN SOME SEA FOG. HEADLINES WILL LIKELY BE NEEDED TUE AS BOTH WINDS AND SEAS ARE EXPECTED TO EXCEED THRESHOLDS AS DEEPENING LOW PRESSURE MOVES ACROSS THE CAROLINAS. STRONG COLD FRONT CROSSES THE WATERS TUE NIGHT WITH STRONG SOUTHWEST FLOW IN ITS WAKE BECOMING WESTERLY. NOT A LOT OF COLD ADVECTION BEHIND THE FRONT SO WINDS MAY NOT BE VERY GUSTY...BUT PINCHED GRADIENT WILL KEEP WINDS 15 TO 20 KT INTO WED MORNING. 2 TO 3 FT SEAS MON AND MON NIGHT WILL BUILD TO 6 TO 9 FT BEFORE COLD FRONT SWEEPS ACROSS THE WATERS TUE NIGHT. SEAS WILL SLOWLY FALL TUE NIGHT AS WINDS BECOME WEST AND THEN NORTHWEST. LONG TERM /WEDNESDAY THROUGH THURSDAY/... AS OF 3 AM SUNDAY...LIGHT WEST TO NORTHWEST FLOW WED AS HIGH PRESSURE MOVES MOVES EAST ACROSS THE GULF COAST. WINDS BECOME LIGHT AND VARIABLE LATE WED NIGHT AS RIDGE AXIS ELONGATES AND SHIFTS SOUTHEAST OF THE AREA. LIGHT RETURN FLOW DEVELOPS BY THU BUT GRADIENT REMAINS WEAK. SPEEDS THROUGH THE PERIOD WILL GENERALLY BE 10 KT OR LESS WITH SEAS 2 TO 3 FT. && .ILM WATCHES/WARNINGS/ADVISORIES... SC...NONE. NC...NONE. MARINE...SMALL CRAFT ADVISORY FROM 2 AM TO 9 AM EST MONDAY FOR AMZ250- 252. && $$ NEAR TERM...DCH/TRA SHORT TERM...III LONG TERM...III AVIATION...HDL
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AREA FORECAST DISCUSSION
NWS MILWAUKEE/SULLIVAN WI
611 PM CST MON DEC 26 2011 .UPDATE... INTRODUCED ISOLD TO SCT LIGHT SHOWERS FOR THIS EVENING WITH THE EXCEPTION OF FAR SE WI. A NARROW TONGUE OF MID LEVEL MOISTURE IS STREAMING AHEAD OF THE APPROACHING UPPER TROUGH FROM THE ERN GREAT PLAINS WITH A NARROW BAND OF PRECIPITATION FROM SW IA NEWD INTO SW WI. ONLY TRACE AMOUNTS HAVE BEEN REPORTED BY METARS BUT THERE PROBABLY IS MINOR MEASURABLE RAINFALL OCCURRING. MESO MODELS ARE DOING WELL PICKING UP PCPN AND THEN DISSIPATE IT AS IT APPROACHES SE WI. && .PREV DISCUSSION... /ISSUED 142 PM CST MON DEC 26 2011/ SHORT TERM... TONIGHT AND TUESDAY - CONFIDENCE...MEDIUM WATER VAPOR/RUC COMBO SHOWS SOUTHERN STREAM ENERGY CRUISING THROUGH NRN TX WITH NORTHERN STREAM WAVE TRAVERSING EAST FROM ND INTO NRN MN. SOME INCREASE IN MOISTURE NOTED OUT AHEAD OF SOUTHERN WAVE. MID/HIGH CLOUDS RACING NORTHEAST FROM ERN IA AND CENTRL IL WILL OVERSPREAD SRN WI THIS EVENING. LOW LEVELS WILL BE SLOW TO SATURATE PER RUC AND NAM BUFKIT SOUNDINGS. IN FACT...THE LOW LEVELS REALLY DO NOT MOISTEN UP UNTIL THE COLD AIR ADVECTION REGIME KICKS IN ON TUESDAY. QPF TIED MORE TO RIGHT REAR QUADRANT AND THIS KEEPS PRECIP JUST TO OUR SE. MODELS GENERATE LIGHT QPF TUESDAY IN COLD AIR ADVECTION REGIME...WITH NORTHERN STREAM MID LEVEL TROUGH PASSAGE. WILL GO WITH THE LOW POP/SHSN IDEA WITH MORE OF A FLURRY SCENARIO IN THE AFTERNOON. OVERALL DEPTH OF MOISTURE LOOKS UNIMPRESSIVE. LOW LEVELS A BIT MORE MOIST IN THE CAA REGIME. TEMPS WILL BE NOTICEABLY COOLER WITH THE CLOUD COVER/GUSTY NW WINDS AND 925 TEMPS DROPPING TO -6 TO -8C. TUESDAY NIGHT AND WEDNESDAY...FORECAST CONFIDENCE...MEDIUM. AS THE STRONG SHORTWAVE MOVES OFF...A MORE WEST/NORTHWEST FAST FLOW IS EXPECTED IN THE MID/UPPER LEVELS. ONE WEAK SHORTWAVE MOVES ACROSS SOUTHERN WISCONSIN WEDNESDAY MORNING WHILE A SECOND STRONGER SHORTWAVE APPROACHES LAKE SUPERIOR AREA LATE WEDNESDAY AFTERNOON. THE PRECIPITATION FROM THIS SHORTWAVE IS EXPECTED TO REMAIN TO THE NORTH. A SURFACE HIGH WILL CROSS WISCONSIN TUESDAY NIGHT BEFORE WARM AIR ADVECTION TAKES HOLD ON WEDNESDAY. LOW LEVELS ARE DRY WITH ONLY MID LEVELS SATURATING ON WEDNESDAY WITH THE APPROACHING SHORTWAVE. WEDNESDAY NIGHT AND THURSDAY...FORECAST CONFIDENCE...MEDIUM. THE SHORTWAVE MOVES ACROSS THE UPPER GREAT LAKES WEDNESDAY NIGHT AS A BROAD ZONAL FLOW DEVELOPS IN THE MID/UPPER LEVELS AS A RATHER WEAK SHORTWAVE MOVES TOWARDS NORTHERN MINNESOTA. ASSOCIATED WEAK SURFACE LOW SHOULD REACH NORTHWEST MINNESOTA THURSDAY AFTERNOON WITH SOUTH FLOW DEVELOPING ACROSS SOUTHERN WISCONSIN. LONG TERM... FRIDAY THROUGH SUNDAY...FORECAST CONFIDENCE MEDIUM. THE MILD WEATHER PATTERN CONTINUES AS THE MODELS CONTINUE THE PARADE OF WEAK SHORTWAVES IN THE FAST ZONAL FLOW. ONE SHORTWAVE MOVES ACROSS FRIDAY. 12Z GFS TAKES A FAST SHORTWAVE JUST NORTH OF LAKE SUPERIOR WHILE THE 00Z ECMWF BEGINS TO DIG A MAJOR TROUGH OVER THE PLAINS. FOR NOW WILL LEAN MORE TOWARD THE GFS. A WEAK TROUGH OF LOW PRESSURE MOVES ACROSS WISCONSIN FRIDAY WHILE WITH A WEAK RIDGE ON THE 12Z GFS. MOTH MODELS DEVELOP A TROUGH OVER THE WESTERN GREAT LAKES SUNDAY...BUT GFS IS FARTHER NORTH WITH THE 00Z ECMWF EXTENDING THE TROUGH INTO SOUTHEAST MISSOURI AND STRENGTHENS IT. NOT READY TO BUY IN TO THIS SCENARIO AND WILL TREND TOWARD THE 12Z GFS. NEW 12Z ECMWF HAS NOW TRENDED TOWARD THE 12Z GFS. MONDAY...FORECAST CONFIDENCE MEDIUM. AS THE UPPER TROUGH DEEPENS ON THE 00Z ECMWF IT TAKES A STRONG SURFACE LOW NORTH INTO LOWER MICHIGAN. MEANWHILE THE GFS QUICKLY PUSHES A SURFACE LOW OFF THE SOUTHEAST CANADIAN COAST WITH HIGH PRESSURE BUILDING OVER THE UPPER MIDWEST. THE GFS IS MORE CONSISTENT WITH THE 06Z DGEX AND WILL TREND MORE TOWARD THESE MODELS. NEW 12Z ECMWF HAS NOW TRENDED MORE TOWARD THE 12Z GFS BUT THE 12Z ECMWF STILLS DIGS THE MID/UPPER TROUGH MORE ACROSS THE EASTERN GREAT LAKES. PREFER THE LOWER APMPLITUDE 12Z GFS/06Z DGEX. AVIATION/00Z TAFS/... MID DECK INCREASES THIS EVENING AS SOUTHWEST FLOW BRINGS MOISTURE UP AND OUT AHEAD OF SOUTHERN STREAM UPPER LOW. LOWER LEVELS NOT PROGGD TO SATURATE UNTIL COLD AIR ADVECTION REGIME KICKS IN ON TUESDAY. WILL GO WITH MVFR CEILINGS. SPOTTY LIGHT PRECIP IS POSSIBLE THOUGH NOT EXPECTING ANYTHING MAJOR WITH COLUMN MOISTURE LOOKING MEAGHER. MARINE... STRONG SOUTHWEST GRADIENT BETWEEN LOW CROSSING SOUTHERN CANADA AND HIGH IN EASTERN US. WINDS HAVE RAMPED UP AND GUSTING TO SCA CRITERIA. WINDS MAY DROP BRIEFLY BELOW ADVISORY CRITERIA LATE TONIGHT AND EARLY TUESDAY BEFORE STRONG PRESSURE RISES AND COLD ADVECTION BEHIND COLD FRONT KICK IN AND KEEP THINGS BRISK INTO TUESDAY EVENING. SMALL CRAFT ADVISORY RUNS FROM TODAY THROUGH EARLY WEDNESDAY FOR SIMPLICITY. && .MKX WATCHES/WARNINGS/ADVISORIES... WI...NONE. LM...SMALL CRAFT ADVISORY UNTIL 9 AM CST WEDNESDAY FOR LMZ643>646. && $$ UPDATE...GEHRING TONIGHT/TUESDAY AND AVIATION/MARINE...COLLAR TUESDAY NIGHT THROUGH MONDAY...HENTZ
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
535 PM CST MON DEC 26 2011 .SHORT TERM...TONIGHT THROUGH THURSDAY 535 PM CST MON DEC 26 2011 535 PM...QUICK UPDATE. BOTH MID CLOUD AND PRECIPITATION COVERAGE A LITTLE MORE THAN PREVIOUSLY FORECAST. HAVE UPDATED THE FORECAST FOR THIS EVENING TO ACCOUNT FOR CLOUDIER SKIES THIS EVENING...AS WELL AS TO INCLUDE ISOLATED/SCATTERED RAIN SHOWERS OVER NORTHEAST IOWA AND SOUTHWEST WISCONSIN. IN ADDITION...WITH TEMPERATURES ALREADY FALLEN TO 37 AT DECORAH...HAVE PUT IN A MIX OF SNOW/SLEET WITH THE RAIN. A COOP OBSERVER IN STANLEY IOWA REPORTED A MIX OF RAIN/SLEET/SNOW IN STANLEY...WHICH CHANGED OVER TO ALL RAIN WHEN DRIVING UP TO OELWEIN. LOOKS LIKE THE BULK OF THE PRECIPITATION SHOULD BE EAST OF THE AREA AROUND 03Z. PREVIOUS FORECAST ISSUED AT 249 PM... THE MAIN FOCUS IN THE SHORT TERM IS ON THE PRECIPITATION CHANCES TONIGHT INTO TOMORROW...FOLLOWED BY ANOTHER SYSTEM WEDNESDAY NIGHT INTO THURSDAY. GUSTY SOUTHWEST WINDS DEVELOPED TODAY AHEAD OF A COLD FRONT THAT CURRENTLY EXTENDS SOUTH OF A SURFACE LOW IN FAR SOUTHWEST ONTARIO DOWN THROUGH EASTERN MINNESOTA AND WESTERN IOWA TOWARD OMAHA. WITH INCREASING CLOUD COVER AND A WEAKENING PRESSURE GRADIENT...WILL BE ALLOWING THE WIND ADVISORY TO EXPIRE AT 3PM THIS AFTERNOON. FURTHER ALOFT...A CUT OFF LOW OVER THE SOUTHERN PLAINS WAS STARTING TO GET A KICK EASTWARD FROM A NORTHERN STREAM TROUGH PROPAGATING EAST THROUGH SOUTHERN CANADA. A FEW SHOWERS HAVE KICKED UP DOWN SOUTH CLOSER TO THE CUT OFF LOW AND SOME OF THE HI- RES MESO MODELS DO CONTINUE TO SHOW SOME RETURNS GOING INTO THE EVENING AHEAD OF THE COLD FRONT...MAINLY IN NORTHEAST IOWA AND SOUTHWEST WISCONSIN. 26.18Z RUC SOUNDINGS OUT OF DBQ/BLR/MSN SHOW A QUICK MOISTENING UP OF THE LOW LEVELS THIS EVENING TOWARD 23-03Z BEFORE THE FRONT COMES THROUGH. THESE THERMAL PROFILES SHOW A WARM LAYER OF 4C AROUND 925MB AND SURFACE TEMPERATURES ABOVE FREEZING...SO ANY PRECIPITATION THAT FALLS TONIGHT AHEAD OF THE FRONT SHOULD STAY IN LIQUID FORM AND NOT REFREEZE. AFTER THIS FIRST COLD FRONT COMES THROUGH...A SECONDARY COLD FRONT WILL SWING AROUND ON THE BACK SIDE OF THE SURFACE LOW AND COME THROUGH THE REGION LATE TONIGHT INTO TOMORROW MORNING. 26.12Z NAM/GFS AND 26.18Z RUC SOUNDINGS SHOW STEEPENING LOW LEVEL LAPSE RATES WITH AN INCREASE IN MOISTURE RIGHT AROUND THE INVERSION. WITH TEMPERATURES IN 925-875MB DROPPING INTO THE -8 TO -10C RANGE...IT SHOULD BE COLD ENOUGH FOR ICE TO FORM. THERE IS NOT MUCH FORCING TO WORK WITH...BUT THE COMBINATION OF STEEP LAPSE RATES...MOISTURE AND ICE AVAILABLE...SHOULD SEE SOME LIGHT SNOW OR FLURRIES WITH A DUSTING OF SNOW ACCUMULATION NOT OUT OF THE QUESTION IN SPOTS. THE 26.12Z GFS APPEARS TO BE AN OUTLIER AT THIS POINT WITH SHOWING MUCH DEEPER MOISTURE ACROSS ALL OF THE REGION AND TRIES TO PUT DOWN A MUCH LARGER AREA OF ACCUMULATING LIGHT SNOW THROUGH TOMORROW MORNING. WITH THE LOW LEVEL MIXING AND A TIGHT PRESSURE GRADIENT IN PLACE...IT WILL BE ANOTHER WINDY DAY TOMORROW WITH WIND GUSTS UP TO 30KTS IN THE HIGHER TERRAIN. A RIDGE OF HIGH PRESSURE WILL MOVE THROUGH TOMORROW NIGHT INTO EARLY WEDNESDAY BEFORE ANOTHER QUICK MOVING MID LEVEL TROUGH PROPAGATES EAST ACROSS SOUTHERN CANADA THROUGH THE MAINLY ZONAL FLOW. THE BETTER FORCING GOES NORTH TOWARD LAKE SUPERIOR WITH THE LOW ON WEDNESDAY BUT ANOTHER QUICK MOVING TROUGH WILL UNDERCUT THIS LOW AND BRING SOME BETTER CHANCES FOR PRECIPITATION WEDNESDAY NIGHT INTO THURSDAY. PRECIPITATION TYPE WILL BE AN ISSUE WITH THE THERMAL PROFILE LIKELY WARMING ENOUGH FOR IT TO POSSIBLY CHANGE OVER TO RAIN...ESPECIALLY ALONG AND SOUTH OF THE I-94 CORRIDOR. .LONG TERM...THURSDAY NIGHT THROUGH MONDAY 249 PM CST MON DEC 26 2011 CONFIDENCE IN THE LONG TERM REMAINS LOW GIVEN THE FAST ZONAL FLOW AND THE DIFFERENCES THAT HAVE BEEN SHOWING UP BETWEEN THE GEM/GFS/ECMWF. RUN TO RUN CONSISTENCY IN THE MODELS HAS NOT BEEN VERY GOOD IN THE EXTENDED...SO HAVE TRIED TO HIGHLIGHT THE BEST CHANCES FOR ANY OVERLAP BETWEEN THESE MODELS...WHICH IS MAINLY THURSDAY NIGHT INTO FRIDAY. AFTER THIS SERIES OF SHORTWAVE TROUGHS COME THROUGH...IT LOOKS LIKE THERE WILL BE A PERIOD OF RIDGING GOING INTO THE WEEKEND. AFTER THIS RIDGE SHIFTS EAST BY SATURDAY NIGHT...THE FOCUS IS ON ANOTHER TROUGH AND HOW DEEP IT DIGS SOUTH. THE 26.12Z GFS KEEPS MORE OF A ZONAL FLOW AND OPEN WAVE WHILE THE 26.12Z ECMWF AND GEM START CARVING OUT A MUCH MORE AMPLIFIED WAVE. THE IMPACT PRECIPITATION WISE FOR OUR AREA IS NOT MUCH AS IT APPEARS THAT THE FOCUS WOULD BE OFF TO THE EAST. && .AVIATION...TONIGHT AND TUESDAY 535 PM CST MON DEC 26 2011 COUPLE OF CONCERNS FOR THE AVIATION FORECAST...MOSTLY RELATING TO A COLD FRONTAL PASSAGE THROUGH THE TAF SITES EXPECTED AROUND 08Z. PRIOR TO 08Z AND THE COLD FRONT...PLAN ON VFR CONDITIONS TO CONTINUE WITH SOUTHWEST TO WEST WINDS HOVERING BETWEEN 10 AND 15 KT. THESE WINDS WILL INCREASE BEHIND THE COLD FRONT WHILE VEERING TO THE NORTHWEST. ANTICIPATING SUSTAINED WINDS OF 15 TO 20 KT AND GUSTS OF 25 TO 30 KT...HIGHEST AT KRST. ALSO...AN AREA OF MVFR STRATUS AND SOME FLURRIES/VERY LIGHT SNOW SHOWERS WILL COME IN BEHIND THE COLD FRONT. PLAN ON THE MVFR STRATUS AND BLUSTERY WINDS TO PERSIST THROUGH THE MORNING. DURING THE AFTERNOON... PARTICULARLY AROUND 20-21Z...HIGH PRESSURE BUILDING IN AND A SURGE OF DRY AIR SHOULD HELP BOTH CLEAR THE STRATUS OUT AND DIMINISH THE WINDS. && .ARX WATCHES/WARNINGS/ADVISORIES... 249 PM CST MON DEC 26 2011 WI...NONE. MN...NONE. IA...NONE. && $$ SHORT TERM...HALBACH/AJ LONG TERM...HALBACH AVIATION...AJ
AREA FORECAST DISCUSSION...UPDATED
NWS MILWAUKEE/SULLIVAN WI
1153 AM CST SUN DEC 25 2011 .UPDATE...CLOUD DECK FROM THE NORTHWEST CONTINUES TO SLIDE SOUTHEAST INTO NORTHERN PORTIONS OF THE AREA. 1000/850MB RELATIVE HUMIDITY FIELDS ON SHORT TERM MODELS CONTINUE TO BRING THESE CLOUDS SOUTHEAST THROUGH MOST OF THE AREA THIS AFTERNOON...LINGERING IN THE EVENING IN THE FAR EAST BEFORE MOVING OFF TO THE EAST. ALSO...AREA RUC FORECAST SOUNDINGS SUGGEST DIURNAL CUMULUS CLOUDS SHOULD HELP FILL IN GAPS WITHIN THIS AREA OF CLOUDS. WILL UPDATE SKY GRIDS TO REFLECT THIS TREND. CLOUDS SHOULD PUT A HALT TO TEMPERATURE RISES ONCE THEY MOVE IN...PERHAPS EVEN FALL A BIT. TEMPERATURES IN THE LOWER 40S SEEN IN SOUTHEAST SECTIONS OF THE AREA WITH GOOD MIXING AND SUNSHINE...DESPITE COLD AIR ADVECTION OCCURRING. UPDATED TEMPERATURES TO REFLECT THESE WARMER READINGS. && .AVIATION/18Z TAFS/...VFR CONDITIONS EXPECTED THROUGH MONDAY ACROSS TAF SITES. VFR CLOUD DECK SHIFTING SOUTHEAST SHOULD CONTINUE TO DO SO THROUGH THE AFTERNOON...REACHING TAF SITES BETWEEN 19Z AND 21Z SUNDAY. THESE CLOUDS SHOULD LINGER AT MADISON UNTIL AROUND 00Z MONDAY...AND BETWEEN 03Z AND 05Z MONDAY AT THE EASTERN SITES. BRISK NORTHWEST SUSTAINED WINDS OF 13 TO 18 KNOTS WILL LINGER UNTIL SUNSET...WITH GUSTS OF 25 TO 29 KNOTS POSSIBLE AT TIMES. WINDS WILL DIMINISH THIS EVENING AND SHIFT SOUTHWEST BY 10Z TO 12Z MONDAY. GUSTY SOUTHWEST WINDS EXPECTED BY 15Z MONDAY...LASTING THROUGH THE DAY. GUSTS TO 25 KNOTS ARE POSSIBLE AT TIMES. && .MARINE...SMALL CRAFT ADVISORY CONTINUES UNTIL 6 PM CST FOR THE NEARSHORE WATERS. BRISK NORTHWEST WINDS OF 15 TO 25 KNOTS WITH GUSTS TO AROUND 30 KNOTS ARE EXPECTED THROUGH TODAY...AS TIGHT PRESSURE GRADIENT LINGERS ACROSS THE AREA. THESE WINDS SHOULD GENERATE HIGH WAVES...MAINLY TOWARD THE OPEN WATERS. THE WINDS AND WAVES SHOULD SUBSIDE QUICKLY THIS EVENING...AS PRESSURE GRADIENT WEAKENS AND MIXING SUBSIDES. && .PREV DISCUSSION... /ISSUED 249 AM CST SUN DEC 25 2011/ TODAY...FORECAST CONFIDENCE...HIGH POTENT UPPER TROUGH OVER MINNESOTA DIVING THROUGH CENTRAL WISCONSIN AROUND DAYBREAK BEFORE HEADING INTO CENTRAL LOWER MICHIGAN BY MIDDAY. STRONG Q-G FORCING WITH 500 MB 12 HOUR HEIGHT FALLS AROUND 120 METERS...PV1.5 DIVING TO 550 MB...AND Q-VECTOR CONVERGENCE ABOVE 30 KNOTS FROM 700-300 MB. HOWEVER...AIRMASS VERY DRY SO NOTHING BUT MID CLOUDS WITH SYSTEM MOVING AWAY AND SOME STRATOCUMULUS UNDER COLD CORE THIS AFTERNOON. COLD FRONT GOES THROUGH FIRST THIS MORNING...WITH BRISK NORTHWEST FLOW IN ITS WAKE TODAY. MEAN WINDS IN SURFACE 850 MB LAYER DO INCREASE TO 35 KNOTS FROM THE NORTHWEST THIS AFTERNOON WITH STRONG COLD ADVECTION AND SUBSIDENCE. SO GUSTS TO 25-30 KNOTS EXPECTED. MILD THIS MORNING WITH 925 MB TEMPS AROUND +3C BUT CRASHING TO -3C BY 18Z AND -5C BY 00Z. LOOKS LIKE STRONG COLD ADVECTION WILL BALANCE TYPICAL DIURNAL RISE...AS TEMPERATURES CURRENTLY IN THE UPPER 30S AND -3C BY MIDDAY SUPPORTS UPPER 30S WITH ADIABATIC LAPSE RATE. TONIGHT...FORECAST CONFIDENCE...HIGH WEAK SURFACE RIDGE BUILDS IN DURING THE NIGHT WITH LOW LEVEL THERMAL TROUGH GOING BY AROUND 06Z. WARM ADVECTION KICKS IN TOWARD SUNRISE...SO MAY SEE TEMPERATURES BOTTOM OUT BETWEEN 06Z AND 09Z AND THEN LEVEL OFF OR PERHAPS RISE BY 12Z. WINDS SHOULD DROP OFF ENOUGH FOR A WEAK INVERSION TO DEVELOP AND SUPPORT LOWER 20S...ESPECIALLY TOWARD THE NORTHWEST WITH LIGHT SNOW COVER. MONDAY AND TUESDAY...FORECAST CONFIDENCE...MEDIUM WINDS QUICKLY RETURN TO OUT OF THE SOUTHWEST FOR MONDAY...BECOMING BREEZY AGAIN LATE MORNING INTO THE AFTERNOON. MODELS HAVE TIGHTENED THE PRESSURE GRADIENT OVER THE LAST DAY...SO GUSTS TO 30 MPH SEEM PROBABLE. WITH THESE WINDS...A DECENT AMOUNT OF SUN...AND WARMING ALOFT...SHOULD HIT 40 OR LOW 40S PRETTY EASILY...ESPECIALLY IN LOCATIONS WITH NO SNOW COVER. CONTINUED THE TREND OF CUTTING BACK POPS FOR MONDAY NIGHT...AS MODELS GENERALLY KEEP THE PRECIP TO THE SOUTH. SOME MID LEVEL FRONTOGENETIC FORCING AND THETA-E ADVECTING ACROSS THE AREA...BUT MODEL SOUNDINGS STRUGGLE TO SATURATE BEFORE FORCING MOVES OUT. ANOTHER SHORTWAVE PROGGED TO SLIDE THROUGH TUESDAY...BUT MOISTURE/FORCING PRETTY LACKING...SO KEPT FORECAST DRY. WILL BE COLD ADVECTING IN THE AFTERNOON BEHIND THE WAVE...SO KEPT HIGHS IN THE MID TO UPPER 30S...THOUGH STILL ABOUT 10 DEGREES ABOVE NORMAL FOR LATE DECEMBER. WEDNESDAY THROUGH SATURDAY...FORECAST CONFIDENCE...LOW TO MEDIUM MODELS SHOWING THE WAVE TRAIN WILL CONTINUE THROUGH THE LATTER HALF OF THE WORK WEEK AND INTO THE WEEKEND. PRETTY POOR AGREEMENT AMONG MODELS AS TO TIMING/STRENGTH OF INDIVIDUAL WAVES...SO ENDED UP WITH LOW POPS FROM THURSDAY ON. THOUGH LOW CONFIDENCE IN DAY TO DAY PRECIP CHANCES...BETTER CONFIDENCE THAT THIS PATTERN WILL ALLOW TEMPS TO REMAIN ABOVE NORMAL THROUGH THE END OF THE MONTH. AVIATION/12Z TAFS/... 925MB WINDS OF 35-40 KNOTS BRIEFLY THIS MORNING FROM THE WEST AND THEN TURNING NORTHWEST DURING THE DAY AT ABOUT 35 KNOTS. FLOW OF 10-15 KNOTS AT THE SURFACE JUST ENOUGH TO KEEP PROBABILITY OF LOW LEVEL WIND SHEAR A BIT TOO LOW TO WARRANT MENTIONING. GOOD MIXING TODAY SHOULD RESULT IN GUSTS OF 25-30 KNOTS AS STRONG GOES BY TO THE EAST OF AREA AND PRESSURE RISES BEHIND COLD FRONT KICK IN. AREA OF MVFR TO VFR STRATOCUMULUS OVER NORTHERN MINNESOTA BENEATH UPPER COLD CORE TROUGH SHOULD MOVE IN FROM LATE MORNING INTO THE MIDDLE AFTERNOON HOURS...BUT CEILINGS SHOULD BE IN 3500 TO 6000 FEET RANGE. MARINE... SURFACE TO 850 MB MEAN WINDS IN NORTHWEST FLOW COLD ADVECTION REGIME ARE ABOUT 35 KNOTS...BUT IT DOES NOT APPEAR THAT MIXED LAYER WILL REACH 850 MB SO EXPECTING GUSTS AROUND 30 KNOTS. PROBABILITY OF FREQUENT GALE FORCE GUSTS TOO LOW TO WARRANT GALE WARNING SO WILL STICK WITH SMALL CRAFT ADVISORY. WINDS SHOULD DROP OFF QUICKLY AROUND DARK AS BOUNDARY LAYER DECOUPLES. A STRONGER LOW PRESSURE AREA THEN MOVES ACROSS SOUTHERN MANITOBA INTO NORTHWEST ONTARIO MONDAY...WITH 925 MB WINDS FROM THE WEST-SOUTHWEST IN THE 45-55 KNOT RANGE. LOW LEVEL STABILITY WILL AGAIN BE AN ISSUE...SO GUSTS IN THE COASTAL WATERS TO AROUND 30 KNOTS ARE AGAIN LIKELY. A MARGINAL GALE IS AGAIN POSSIBLE...BUT MORE LIKELY TOWARD OPEN WATER SO ODDS FAVOR NEEDING ANOTHER SMALL CRAFT ADVISORY MONDAY AFTERNOON AND EARLY EVENING. && .MKX WATCHES/WARNINGS/ADVISORIES... WI...NONE. LM...SMALL CRAFT ADVISORY UNTIL 6 PM CST THIS EVENING FOR LMZ643>646. && $$ UPDATE...WOOD TODAY/TONIGHT AND AVIATION/MARINE...CRAVEN MONDAY THROUGH SATURDAY...DDV
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
1058 PM CST SAT DEC 24 2011 .SHORT TERM...TONIGHT THROUGH TUESDAY 247 PM CST SAT DEC 24 2011 TWAS THE NIGHT BEFORE CHRISTMAS WHEN ALL THROUGH THE UPPER MISSISSIPPI RIVER VALLEY...A TROUGH WAS STIRRING THAT WILL BRING CLOUDS TO COVER THE GALLEY. SPLIT UPPER LEVEL FLOW WILL KEEP THE REGION DRY THROUGH THE HOLIDAY WEEKEND INTO EARLY NEXT WEEK WITH ABOVE NORMAL TEMPERATURES ON TAP. SUNNY SKIES AND LOW LEVEL WARM AIR ADVECTION BROUGHT TEMPERATURES INTO THE LOW 40S ACROSS MUCH OF THE REGION AND IN TURN MELTED AWAY THE LITTLE SNOW THAT WAS LEFT FROM THIS PAST WEEK. A MID LEVEL TROUGH CURRENTLY IN THE CANADIAN ROCKIES WILL DIVE DOWN THROUGH THE NORTHWESTERLY FLOW TOWARD THE NORTHERN GREAT LAKES TONIGHT. THE SOUTHERN EXTENT OF THIS TROUGH WILL PROVIDE A QUICK SHOT OF MID LEVEL QG FORCING TO THE REGION...BUT DOES NOT APPEAR TO BE DEEP ENOUGH...BASED ON 24.12Z NAM/GFS AND 24.18Z RUC SOUNDINGS...TO OVERCOME THE SURFACE TO 700MB DRY LAYER TO PRODUCE ANY PRECIPITATION. THE 24.18Z RUC SHOWS 600-400MB RH TO BE ON THE INCREASE TOWARD ROCHESTER THIS EVENING WITH THESE HIGH CLOUDS LINGERING THROUGH OUT THE REGION OVERNIGHT. WITH CONTINUED LOW LEVEL WARM AIR ADVECTION GOING AND THE HIGH LEVEL CLOUD COVER TONIGHT...LOW TEMPERATURES WILL NOT DROP OFF MUCH BELOW FREEZING. AS THIS FEATURE PASSES THROUGH...A LOW LEVEL COLD FRONT WILL MOVE THROUGH TOWARD DAYBREAK CHRISTMAS MORNING WITH 850MB TEMPERATURES DROPPING FROM AROUND 1C DOWN TO -3C. THUS...HIGHS FOR CHRISTMAS WILL BE A LITTLE LOWER THAN WHAT THEY WERE TODAY BUT STILL WELL ABOVE NORMAL. OVERALL...IT WILL BE AN IDEAL TRAVEL DAY FOR THE HOLIDAY WITH SUNNY SKIES AND NORTHWEST WINDS AROUND 10KTS. A RIDGE AXIS WILL THEN MOVE THROUGH THE REGION ON SUNDAY NIGHT WITH WARMER LOW LEVEL AIR ADVECTING BACK IN ON MONDAY ON THE BACK SIDE OF THE RIDGE. THIS WILL LIKELY BE THE WARMEST DAY OVER THE NEXT 7 DAYS WITH HIGHS JUMPING BACK INTO THE LOW 40S WITH NO SNOW COVER LEFT TO RESTRICT THESE TEMPERATURES. WINDS WILL BE FAIRLY GUSTY AHEAD OF A COLD FRONT WITH A TIGHTENING PRESSURE GRADIENT SETTING UP. SUSTAINED WINDS OF AROUND 20KTS LOOK POSSIBLE...PARTICULARLY AT ROCHESTER...WITH 24.12Z NAM AND GFS SUGGESTING THAT MOMENTUM TRANSFER WILL BRING SOME 30KT GUSTS DOWN TO THE SURFACE. GOING INTO MONDAY NIGHT...THE 24.12Z NAM IS AN OUTLIER WITH ITS SOLUTION OF BRINGING SOME PRECIPITATION CLOSE TO THE REGION INTO NORTHERN ILLINOIS AND SOUTHERN WISCONSIN. IT BRINGS THE CUT OFF LOW IN SOUTHERN NEW MEXICO UP TOWARD THE GREAT LAKES WHILE THE OTHER MODELS SHOW THE LOW STAYING OFF TO THE SOUTH. THE PREFERRED SOLUTIONS FROM HPC ON THIS FEATURE ARE WITH THE 24.12Z UKMET/ECMWF/GEM WHICH ALL KEEP THE LOW WELL TO THE SOUTH AND DRY HERE. .LONG TERM...TUESDAY NIGHT THROUGH SATURDAY 247 PM CST SAT DEC 24 2011 CONFIDENCE DROPS OFF QUITE A BIT GOING INTO THE EXTENDED PERIOD WITH AN ACTIVE NORTHWESTERLY FLOW SETTING UP ALOFT. THE 24.12Z GEM IS THE FIRST TO INTRODUCE SOME PRECIPITATION ON WEDNESDAY WITH A TROUGH AND SURFACE LOW COMING THROUGH DURING THE DAY. THIS SOLUTION WOULD BRING A LIGHT ACCUMULATING SNOW ON WEDNESDAY...BUT THE 24.12Z GFS AND ECMWF ARE SLOWER AND DEEPER WITH THIS TROUGH AND BRING IT IN WEDNESDAY NIGHT INTO THURSDAY. HAVE GONE WITH THE GFS/ECMWF TIMING AT THIS POINT. AFTER A BRIEF BREAK AS A RIDGE AXIS COMES THROUGH...ANOTHER TROUGH WILL DROP DOWN INTO THE REGION WITH A SURFACE LOW FORMING OVER THE DAKOTAS AND TRACKING EAST. THE 24.12Z ECMWF IS FURTHER NORTH WITH THIS TRACK WHILE THE 24.12Z GFS IS MUCH MORE AMPLIFIED AND DROPS IT FURTHER SOUTH. HAVE KEPT SOME SMALL CHANCES FOR PRECIPITATION IN THERE GOING INTO NEXT WEEKEND. TEMPERATURE WISE IT LOOKS FAIRLY SEASONAL WITH NO BIG WARM UPS OR COLD SPELLS DESPITE BEING IN THE NORTHWESTERLY FLOW. && .AVIATION...THROUGH 06Z MONDAY 1058 PM CST SAT DEC 24 2011 MAIN AVIATION CONCERN IS THE WINDS. A FAIRLY TIGHT PRESSURE GRADIENT OVER THE TAF SITES...BETWEEN LOW PRESSURE IN NORTHWEST ONTARIO AND HIGH PRESSURE OVER THE CENTRAL PLAINS...WILL REMAIN IN PLACE TODAY. LOOK FOR SUSTAINED WINDS OF 10 TO 15 KT TO PERSIST THROUGH THE DAY. HOWEVER...ONCE DAYTIME MIXING STARTS...WITHIN A FEW HOURS GUSTS TO 20-25 KT SHOULD DEVELOP...ALONG WITH WINDS VEERING TO NORTHWESTERLY. A SURFACE RIDGE AXIS IS FORECAST TO CROSS THE TAF SITES SUNDAY EVENING...HELPING TO END THE GUSTS AND DIMINISH THE WINDS BELOW 10 KT. OTHERWISE...EXPECT VFR CONDITIONS TO CONTINUE THROUGH SUNDAY NIGHT WITH PLENTIFUL LOW TO MID LEVEL DRY AIR. && .ARX WATCHES/WARNINGS/ADVISORIES... 247 PM CST SAT DEC 24 2011 WI...NONE. MN...NONE. IA...NONE. && $$ SHORT TERM...HALBACH LONG TERM...HALBACH AVIATION...AJ
AREA FORECAST DISCUSSION
NWS CHARLESTON SC
444 AM EST TUE DEC 27 2011 .SYNOPSIS... A STRONG LOW PRESSURE SYSTEM WILL LIFT THROUGH THE SE THIS MORNING AND INTO THE CENTRAL APPALACHIANS AND VIRGINIA THIS AFTERNOON. A STRONG COLD FRONT TRAILING FROM THE LOW WILL PASS THROUGH LATE THIS MORNING AND THIS AFTERNOON. THE FRONT WILL BE PRECEDED BY WIDESPREAD SHOWERS AND A FEW STRONGER THUNDERSTORMS...RESULTING IN SOME MUCH NEEDED RAINFALL AND THE POSSIBILITY OF ISOLATED SEVERE WEATHER. HIGH PRESSURE WILL THEN BUILD INTO THE AREA TONIGHT THROUGH THURSDAY. A DRY COLD FRONT MAY MOVE IN LATE FRIDAY...BEFORE HIGH PRESSURE RETURNS FOR SATURDAY. ANOTHER COLD FRONT MAY AFFECT THE AREA EARLY NEXT WEEK. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... A VERY ACTIVE NEAR TERM PERIOD IS ON TAP FOR TODAY WITH MULTIPLE HAZARDS EXPECTED TO AFFECT SOUTHERN SC/SOUTHEAST GA AND THE ADJACENT COASTAL WATERS. OVERALL...THERE ARE NO SIGNIFICANT CHANGES TO THE GENERAL THINKING ABOUT THE UPCOMING EVENT. THE MAIN CHANGES ARE FOR THE TIMING OF THE PRECIP THROUGH THE FORECAST AREA AND FOR UPDATES TO EXPECTED WINDS. AS HAS BEEN WELL DOCUMENTED IN PRECEDING FORECASTS...STRONG SYNOPTIC SCALE FORCING WILL MOVE ACROSS THE REGION TODAY. A POTENT CLOSED UPPER LOW OVER THE LOWER MS VALLEY WILL CONTINUE TO OPEN UP AND PHASE WITH NORTHERN STREAM ENERGY DIVING ACROSS THE UPPER MIDWEST. DIVERGENCE ALOFT ASSOCIATED WITH A 120 KT JET COMBINED WITH STRONG LOW LEVEL LINEAR FORCING ALONG A COLD FRONT WILL IS EXPECTED TO PUSH A BAND OF SHOWERS AND PERHAPS EMBEDDED THUNDERSTORMS ACROSS THE REGION. NOW LETS TAKE A LOOK AT A FEW ASPECTS OF THE EVENT. TIMING OF PRECIP...RECENT OPERATIONAL MODEL RUNS HAVE GREATLY SPED UP THE ARRIVAL OF THE APPROACHING SYSTEM. REGIONAL SATELLITE IMAGERY SHOWS ONGOING PRECIP SURROUNDING THE FORECAST AREA TO THE NW AND W WITH THE MAIN EVENTUAL CONVECTIVE LINE STARTING TO TAKE SHAPE OVER THE NE GULF AND FL PANHANDLE. THE 05Z HRRR SEEMS TO HAVE THE BEST HANDLE ON THE CURRENT PRECIP COVERAGE AND EVOLUTION AND THE POP TREND FOR TODAY GENERALLY FOLLOWS IT. THE PRE FRONTAL LINE OF SHOWERS/CONVECTION WILL BEGIN PUSHING INTO THE FAR WESTERN PORTION OF THE FORECAST AROUND AROUND 12Z. I THEN TAKE THE AREA OF 100 POP AND MARCH IT EASTWARD WITH THE BAND ENTERING THE CHARLESTON AREA IN THE 14-15Z TIME FRAME. THE LINE OF SHOWERS AND/OR THUNDERSTORMS WILL BE PUSHING OFFSHORE BY THE LATE MORNING WITH JUST LINGERING SHOWERS INTO THE EARLY AFTERNOON FOR MOST OF THE AREA. SEVERE WEATHER POTENTIAL...THE DEEP LAYER WIND FIELDS ASSOCIATED WITH THIS SYSTEM CONTINUE TO LOOK QUITE IMPRESSIVE AND A HIGH SHEAR/LOW CAPE ENVIRONMENT IS ANTICIPATED. A POWERFUL 850 MB JET...ON THE ORDER OF 50-60 KTS...WILL TRAVERSE THE AREA THROUGH THE LATE MORNING RESULTING IN 0-3 KM WIND SHEAR OF 50 KTS OR MORE THROUGH THE LATE MORNING HOURS. SHEAR IS NOT THE PROBLEM WITH THIS SYSTEM AND THE LIMITING FACTOR FOR SEVERE WEATHER WILL BE INSTABILITY. GIVEN THAT THE SYSTEM IS EXPECTED TO MOVE THROUGH EARLIER IN THE DAY THAN WITH PREVIOUS FORECASTS...THE TIME WINDOW FOR DESTABILIZATION IS QUITE SHORT. IN FACT...WITH ONGOING PRECIP AND DENSE CLOUD COVER...IT WILL BE DIFFICULT TO GET MUCH IN THE WAY OF SURFACE BASED INSTABILITY. MODELS DO HINT AT A TIME IN THE LATE MORNING WHERE INSTABILITY COULD DEVELOP AND PRIMARILY OVER THE TRI COUNTY AREA AND ALONG THE IMMEDIATE COAST. GIVEN THE STRONGLY SHEARED AND WEAKLY UNSTABLE ENVIRONMENT IN THE PRESENCE OF STRONG LINEAR FORCING...THE PRIMARY CONVECTIVE MODE WOULD BE LINE SEGMENTS CAPABLE OF PRODUCING DAMAGING WIND GUSTS. IN THE EVENT THAT THERE IS ENOUGH INSTABILITY...THERE COULD BE A BRIEF ISOLATED BROKEN S TYPE TORNADO. THE MAIN TIME PERIOD FOR POTENTIAL SEVERE WEATHER LOOKS TO BE BETWEEN 9AM AND 1PM. GUSTY WINDS...AS THE STRENGTHENING LOW LEVEL JET MOVES THROUGH THE AREA STRONG GUSTY WINDS WILL DEVELOP ACROSS PORTIONS OF THE AREA. I HAVE HOISTED A WIND ADVISORY WHICH INCLUDES THE TRI COUNTY AREA AND BEAUFORT/COASTAL COLLETON COUNTIES. MIXING (ALBEIT LIMITED) WILL BEGIN AROUND 13Z JUST AHEAD OF THE APPROACHING PRECIP BAND. AS IT DOES YOU ONLY HAVE TO GO UP TO 500-1000 FEET TO REACH WINDS IN THE 35-40 KT RANGE BASED ON MODEL SOUNDINGS. WIND GUSTS OF 40-45 MPH WILL BE POSSIBLE IN THE AFOREMENTIONED AREAS AND WILL EXTEND THE ADVISORY THROUGH THE LATE AFTERNOON AS WINDS WILL REMAIN ELEVATED IN THE SW TO W FLOW ONCE THE PRECIP BAND PASSES THROUGH. TEMPERATURES WILL CONTINUE TO RISE THIS MORNING AS A WARM FRONT PASSES THROUGH DURING THE NEXT FEW HOURS. UPPER 60S CAN BE EXPECTED RIGHT ALONG THE COAST FROM SAVANNAH TO CHARLESTON WITH LOW TO MID 60S FURTHER INLAND. && .SHORT TERM /6 PM THIS EVENING THROUGH FRIDAY/... TONIGHT...DEEP LOW PRESSURE OVER THE NE CONTINUES TO STRENGTHEN AS IT MOVES INTO SE CANADA OVERNIGHT. THE TRAILING COLD FRONT WILL HAVE SHIFTED INTO THE ATLANTIC BY NIGHTFALL OFF OUR COASTS...AND HIGH PRESSURE WILL STEADILY BUILD FROM THE WEST THROUGH THE NIGHT. STRONG COLD ADVECTION EARLY WILL SLACKEN OFF AFTER MIDNIGHT...KEEPING BREEZY CONDITIONS GOING UNTIL LATE EVENING OR THE OVERNIGHT HOURS. AS SKIES CLEAR OUT...TEMPS WILL DROP STEADILY...BOTTOMING OUT BETWEEN 35 AND 40 DEGREES MOST LOCALES. LAKE WINDS...ONCE THE WIND ADVISORY COMES DOWN FOR BERKELEY COUNTY IT WILL NEED TO BE REPLACED BY A WIND ADVISORY ON LAKE MOULTRIE TONIGHT...AS COLD ADVECTION MOVING ACROSS THE WARMER LAKE WATERS WILL ALLOW FOR GOOD MIXING OF 20-30 KT WITHIN THE BOUNDARY LAYER. WEDNESDAY...A DRY WEST TO NW FLOW PREVAILS ALOFT...AS HIGH PRESSURE AT THE SURFACE MOVES IN FROM THE WEST. WEAK COLD ADVECTION IN THE MORNING WILL BE OFFSET BY DOWNSLOPE FLOW OFF THE MOUNTAINS AND PLENTY OF SUNSHINE...BUT WITH 850 MB TEMPS ONLY AROUND 2-3C NORTH AND 4-5C SOUTH...WE LOOK FOR MAX TEMPS MAINLY IN THE UPPER 50S. WEDNESDAY NIGHT IS THEN THE COLDEST NIGHT OF THE FORECAST PERIOD...AS THE HIGH SHIFTS CLOSER TO THE AREA AND GEOSTROPHIC WINDS FALL TO UNDER 10 KT. THIS ALLOWS FOR EXCELLENT RADIATIONAL COOLING AND WILL RESULT IN MIN TEMPS 30-35 INLAND FROM US-17...AND CLOSER TO 40 NEAR THE COAST. THURSDAY...HIGH PRESSURE SLIPS A LITTLE SOUTH AS A CLIPPER TYPE LOW PRESSURE SYSTEM MOVES THROUGH THE GREAT LAKES REGION. AFTER THE CHILLY START...ABUNDANT SUNSHINE AND DOWNSLOPE FLOW OFF THE APPALACHIANS WILL ALLOW FOR US TO TOP OUT WITHIN A COUPLE OF DEGREES EITHER SIDE OF 60. FRIDAY...AS THE LOW TO THE NORTH PUSHES EAST...A TRAILING COLD FRONT WILL MOVE APPROACH LATE IN THE DAY. BUT GIVEN THAT THE FLOW ALOFT IS GENERAL ZONAL AND ANY SHORT WAVE ENERGY REMAINS NORTH...THE FRONT LOOKS TO COME THROUGH DRY. COMPRESSIONAL HEATING AHEAD OF THE FRONT...AND OFFSHORE FLOW AND 850 MB TEMPS CLIMBING TO NEAR 9-10 C WILL BOOST AFTERNOON READINGS TO THE LOWER AND MIDDLE 60S. && .LONG TERM /FRIDAY NIGHT THROUGH MONDAY/... QUASI-ZONAL FLOW OR EVEN SHORT WAVE RIDGING ALOFT WILL PREVAIL LATE THIS WEEK...BEFORE THE PATTERN SHOWS SIGNS OF CHANGING EARLY NEXT WEEK. THE MID/UPPER SLOW WILL SEE THE FORMATION OF A TROUGH IN THE EAST AND RIDGING OUT WEST. THIS WILL ALLOW FOR SOME COLDER AIR TO INVADE THE EASTERN UNITED STATES...BUT TO WHAT MAGNITUDE HAS YET TO BE DETERMINED. AS THE PATTERN ALOFT TRANSITIONS OVER WE WILL SEE A COLD FRONT MOVING THROUGH EARLY NEXT WEEK...ALTHOUGH THERE ARE SOME TIMING UNCERTAINTIES AND AS TO WHETHER OR NOT IT WILL COME THROUGH DRY OR WITH SOME PRECIP. FOR NOW WE PREFER TO KEEP A DRY FORECAST GOING THROUGH TUESDAY...CAPPING POPS EARLY NEXT WEEK AT A SILENT 14 PERCENT. TEMPS WILL BE ABOVE NORMAL THROUGH THE WEEKEND...THEN TREND TOWARD BELOW NORMAL LEVELS MONDAY AND TUESDAY OR NEXT WEEK. && .AVIATION /10Z TUESDAY THROUGH SATURDAY/... WARM ADVECTION RAINS LOOK TO REMAIN WEST AND NW OF THE TERMINALS OVERNIGHT INTO THE EARLY MORNING HOURS TUESDAY...BEFORE CONVECTIVE SHRA AND POSSIBLE TSRA MOVES IN DURING THE MID MORNING AND EXITS INTO THE ATLANTIC DURING THE AFTERNOON. VFR CEILINGS AT BOTH KCHS AND KSAV OVERNIGHT WILL LOWER TO MVFR CEILINGS FROM 1330Z TO 18-19Z...AS CONVECTION MOVES IN FROM THE WEST. PERIODIC IFR WEATHER MAY OCCUR...ESPECIALLY AS A SQUALL LINE MOVES THROUGH FROM ABOUT 15-16Z THROUGH ABOUT 17-18Z. ITS IS DURING THESE FEW HOURS THAT WE HAVE OUR BEST CHANCE OF EXPERIENCING TSRA AND POSSIBLE WIND GUSTS UP NEAR 40 KT. VFR CONDITIONS WILL THEN RETURN FOR THE MID AFTERNOON INTO TONIGHT. WIND FIELDS AT THE TERMINALS WILL BE IMPRESSIVE THROUGH THE FORECAST PERIOD. INITIALLY THE SURFACE WINDS WILL REMAIN DECOUPLED ENOUGH WHERE LOW LEVEL WIND SHEAR OCCURS THROUGH EARLY TUESDAY MORNING. EVENTUALLY SURFACE WINDS INCREASE...BUT GIVEN A 45-50 KT LOW LEVEL JET TRAVERSING THE AREA...WE HAVE MAINTAINED WIND SHEAR THROUGH 15-16Z...EVEN THOUGH SURFACE WINDS WILL BE GUSTY AS WELL. MIXING HEIGHTS WILL CLIMB IN WAKE OF A COLD FRONT THIS AFTERNOON...MAINTAINING THE STRONG AND GUSTY SURFACE WINDS...AS THEY SHIFT FROM SW TO WEST WITH THE PASSAGE OF THE FRONT. WINDS DIMINISH SLIGHTLY WITH SUNSET...BUT REMAIN GUSTY THROUGH THE NIGHT. EXTENDED AVIATION OUTLOOK...VFR CONDITIONS WILL PREVAIL. && .MARINE... TODAY...AN AREA OF LOW PRESSURE WILL MOVE NORTHWARD INTO THE CENTRAL APPALACHIANS WITH A STRONG COLD FRONT MOVING INTO THE REGION THIS MORNING. AS IT DOES SO...A POWERFUL LOW LEVEL JET WITH PUSH ACROSS THE LOCAL WATERS SETTING UP THE CONDITIONS FOR A STRONG WIND EVENT. AFTER ANALYZING MODEL SOUNDINGS FOR THE LOCAL WATERS...CONFIDENCE HAS INCREASED SUFFICIENTLY TO UPGRADE THE SCA/S TO GALE WARNINGS FOR THE OUTER GA WATERS...THE NEARSHORE CHARLESTON WATERS...AND THE CHARLESTON HARBOR. FREQUENT GUSTS TO 35 KTS CAN BE EXPECTED IN THESE AREAS BEGINNING JUST AFTER SUNRISE AND CONTINUING THROUGH THE DAY. CONDITIONS WILL BE CLOSE TO GALE WARNING CRITERIA FOR THE REMAINDER OF THE NEARSHORE WATERS BUT CONFIDENCE ISN/T AS HIGH THERE. CONDITIONS WILL NEED TO MONITORED FOR POSSIBLE UPGRADES TO AMZ 352 AND 354. WINDS JUST AHEAD OF THE MAIN PRECIP BAND BE OUT OF THE S...WITH SOME EVEN HIGHER GUSTS POSSIBLE IN ANY THUNDERSTORMS THE DEVELOP WITHIN THE BAND. THE MAIN AREA OF PRECIP SHOULD CLEAR MOST OF THE WATERS BY THE EARLY AFTERNOON AND WINDS WILL BECOME MORE SW BEHIND IT. SEAS WILL BUILD THROUGH THE DAY AND WILL REACH UP TO 8 FEET CLOSE TO 20 NM ACROSS THE NEARSHORE CHARLESTON WATERS. CONCERNING A POSSIBLE HIGH SURF ADVISORY...IT STILL LOOKS LIKE THE DURATION OF SOUTHERLY FETCH WILL BE TOO SHORT TO MAKE AN ADVISORY NECESSARY. TONIGHT...COLD ADVECTION WILL INTENSIFY IN WAKE OF THE COLD FRONT AND DEPARTING LOW TO THE DISTANT NORTH...AND WE ARE LOOKING AT SOLID SCA/S FOR ALL WATERS FROM 0-20 NM AND IN THE CHARLESTON HARBOR. IT/LL BE CLOSE TO GALES ACROSS THESE WATERS...BUT IT LOOKS LIKE ANY FREQUENCY OF GUSTS WILL BE CLOSER TO 30 KT RATHER THAN 35 KT. ACROSS THE OUTER GA WATERS...ANY DECREASE IN WINDS THIS EVENING WILL ONLY BE TEMPORARY AS EXCELLENT MIXING ALLOWS FOR GALE FORCE GUSTS TO AGAIN ARRIVE ACROSS AMZ374. THE OFFSHORE FETCH WILL ALLOW FOR SEAS TO REMAIN UNDER 5 OR 6 FT WITHIN 20 NM OF SHORE...BUT WILL STILL REACH AS HIGH AS 8 OR 9 FT OUT NEAR 60 NM OFFSHORE. WEDNESDAY...MARINE CONDITIONS WILL RAPIDLY IMPROVE DURING THE MORNING AS COLD ADVECTION WANES AND THE PRESSURE GRADIENT BEGINS TO RELAX AS HIGH PRESSURE BUILDS IN FROM THE WEST. ALL HEADLINES WILL COME DOWN BY NO LATER THAN 10-11 AM. THURSDAY THROUGH FRIDAY...RELATIVELY QUIET CONDITIONS WILL PREVAIL WITH HIGH PRESSURE OVER OR JUST SOUTH OF THE MARINE AREA...AND A MAINLY OFFSHORE FLOW TO PREVAIL. A COLD FRONT LOOKS TO MOVE THROUGH LATE FRIDAY OR FRIDAY NIGHT. WINDS AND SEAS WILL BE NOWHERE NEAR ANY SCA CRITERIA. SATURDAY THROUGH SUNDAY...HIGH PRESSURE WILL BUILD FROM THE NORTH...AND THEN SLIDES EAST INTO THE ATLANTIC. ALTHOUGH AN OFFSHORE FLOW DEVELOPS...WIND SPEEDS WILL REACH NO MORE THAN 10 OR 15 KT...AND SEAS WILL BE LIMITED TO ONLY 2 OR 3 FT. MONDAY THROUGH TUESDAY...IT LOOKS LIKE ANOTHER COLD FRONT WILL IMPACT THE AREA EARLY NEXT WEEK...FOLLOWED BY STRONG HIGH PRESSURE FROM THE WEST AND NW. WINDS AND SEAS WILL RISE...AND ALTHOUGH PROBABILITIES ARE LOW...WE CAN/T RULE OUT THE POSSIBILITY OF SOME SCA/S WITHIN THE COLDER AIR REGIME. && .TIDES/COASTAL FLOODING... THE MORNING HIGH TIDE IN CHARLESTON IS EXPECTED TO APPROACH SHALLOW COASTAL FLOODING CRITERIA. CURRENT OBS ARE RUNNING A LITTLE MORE THAN A FOOT ABOVE PREDICTED DUE TO THE INCREASING SE FLOW. THE EXTRA-TROPICAL GUIDANCE CURRENTLY KEEPS THE FORECAST JUST BELOW 7 FEET...BUT WE WILL HAVE TO MONITOR OBS OVER THE NEXT FEW HOURS CLOSELY FOR INCREASING DEPARTURES AND A COASTAL FLOOD ADVISORY MAY BE NEEDED. && .CHS WATCHES/WARNINGS/ADVISORIES... GA...NONE. SC...WIND ADVISORY UNTIL 5 PM EST THIS AFTERNOON FOR SCZ044-045- 048>050-052. MARINE...SMALL CRAFT ADVISORY UNTIL 7 AM EST WEDNESDAY FOR AMZ352. GALE WARNING UNTIL 5 PM EST THIS AFTERNOON FOR AMZ330-350. SMALL CRAFT ADVISORY UNTIL 4 AM EST WEDNESDAY FOR AMZ354. GALE WARNING UNTIL 4 AM EST WEDNESDAY FOR AMZ374. && $$
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
334 AM CST TUE DEC 27 2011 .DISCUSSION... 330 AM CST THE FORECAST CHALLENGES ARE FIRST ON THE IMMEDIATE SHORT TERM WITH PRECIPITATION GRADUALLY SHIFTING EASTWARD THIS MORNING...THEN THE LAKE EFFECT SHOWER POTENTIAL INTO NORTHWEST INDIANA THIS AFTERNOON AND EVENING. THE ACTIVE FLOW PATTERN ACROSS THE NORTHERN U.S. AND SOME UNDULATIONS IN THIS INTO THE NEW YEAR KEEP THE FORECAST INTERESTING LOOKING FORWARD. SHORT TERM...LOW PRESSURE IS DEVELOPING FAIRLY RAPIDLY UNDER STRONG JET SUPPORT ACROSS WESTERN KY. MOIST ADVECTION ALOFT AND ASSOCIATED ASCENT CONTINUES TO WORK ITS WAY ACROSS NORTHWEST INDIANA. AN ELONGATED NORTHERN STREAM WAVE PUSHING EAST ACROSS THE REGION HAS INTERACTED WITH THIS...HELPING TO PRODUCE BANDS OF MODERATE PRECIP AT TIMES WHERE CONVERGENCE OF ECHOES WAS OBSERVED /AND LIKELY IMPLYING FRONTOGENETIC FORCING/. WITHIN THESE...A FEW REPORTS OF SLEET WERE OBSERVED/REPORTED OR ESTIMATED THROUGH UNKNOWN PRECIP AUTOMATED REPORTS. STRONGER FORCING LIFTING NORTH ACROSS EASTERN IL/WESTERN IN HAS HELPED TO LEAD TO EVAPORATIONAL COOLING SUPPORTING SNOW...AND BENTON COUNTY REPORTED A COATING OF SNOW ON THEIR PAVEMENT AS OF 300 AM. EXPECT THE AREAS RECEIVING PRECIPITATION AT DAYBREAK TO BE MAINLY A WET SNOW...WITH A LITTLE LIGHT RAIN POSSIBLY JUST BEFORE IT ENDS ON THE WESTERN PERIPHERY. THE SHIELD OF PRECIP WILL TAKE A WHILE TO EVOLVE EAST OUT OF THE AREA BASED ON THE QG FORCING ON THE RUC AS WELL AS WATER VAPOR TRENDS WITH THE DRY SLOT NOSE LIFTING INTO CENTRAL IN HELPING TO KEEP MAINLY SNOW GOING IN THE SOUTHEAST FORECAST AREA THIS MORNING. MAXIMUM ACCUMULATIONS NEAR AN INCH TOWARDS FOWLER AND RENSSALEAR STILL LOOK VALID. IN THE FAR SOUTH AND SOUTHEAST CHICAGO METRO WHILE SNOW MAY STILL BE OCCURRING THROUGH 9 AM OR SO...NO ACCUMULATION IS EXPECTED. THIS AFTERNOON...STRONG NORTH TO NORTHWEST WINDS IN THE WAKE OF THE SYSTEM ESTABLISH THEMSELVES DOWN THE FETCH OF LAKE MI THIS AFTERNOON. CONVERGENCE STREAMLINES FROM THE 27.06 NAM FAVOR A CORRIDOR OF SATURATED CONVERGENCE CENTERED ON MICHIGAN CITY...WITH SOME FURTHER WEST TOWARDS PORTER COUNTY. LAKE INDUCED EQUILIBRIUM LEVELS ARE PROJECTED OVER 5000 FT ON THE NAM FOR LATE THIS AFTERNOON AND EVENING AND THUS HAVE INCREASED POPS IN THAT AREA FOR SOME SNOW SHOWERS. FROM THIS...ONLY AN ADDITIONAL DUSTING IS EXPECTED WITH POTENTIAL FOR MORE JUST EAST OF THE FORECAST AREA. TONIGHT THROUGH THURSDAY...THE TEMPERATURES TONIGHT WILL BE A BATTLE BETWEEN THE COLD AND DRY AIR ADVECTION THIS EVENING AND THEN MID TO HIGH CLOUDS ON THE INCREASE FROM THE WEST OVERNIGHT WITH AN APPROACHING SHORT WAVE. IN ADDITION...LINGERING STRATOCU IN THE CAA REGIME IS LIKELY EARLY THIS EVENING...AND THAT MAY RESIDE THROUGH A GOOD PART OF THE NIGHT IN EASTERN AREAS. MODEL SPREAD REFLECTS THIS...VARYING UP TO TEN DEGREES IN SOME LOCATIONS. CONFIDENCE IS THUS MINIMAL ON TONIGHTS LOWS...AND AM NEAR THE CENTER OF THE SPREAD AT THIS TIME. A STRONGER SHORT WAVE ARRIVES INTO SOUTHERN WI ON LATE WEDNESDAY NIGHT INTO THURSDAY MORNING. THIS IS A TRUE QUICK MOVING CLIPPER...WITH ITS BEST MOISTURE SUPPORT ALONG AND NORTH OF ITS PATH WHERE THE TIGHT MID- LEVEL THERMAL GRADIENT EXISTS. WHILE THERE IS FAIRLY STOUT 850-600 MB WAA AHEAD OF THIS FEATURE WED AFTERNOON AND EVENING...THE COLUMN LOOKS MUCH TOO DRY FOR PRECIP. SO ONLY HAVE POPS NEAR THE WI STATE LINE WITH THE ACTUAL LOW CENTER PASSAGE. THURSDAY NIGHT...WHAT HAD BEEN A DEEP SLOW-MOVING LOW IN THE LONGER RANGE FORECAST DAYS AGO HAS TRENDED TOWARDS A SHARP SOUTHEAST DIVING CLIPPER THAT STILL IS FAIRLY DEEP IN PRESSURE FOR CLIPPERS /~1002 MB/. THE PATH ON THE GFS AND EC FAVOR OUR AREA TO SEE SOME PRECIP...BUT EVEN A SLIGHT SHIFT NORTH OR SOUTH WOULD GREATLY REDUCE THEM AS IT IS A FAIRLY NARROW AXIS OF PRECIP WITH SUCH A STRUCTURE. INDEED THE 27.06 NAM IS A SOLUTION THAT IS FURTHER NORTH WITH LITTLE QPF. THE EC FOR TWO CONSECUTIVE RUNS HAS BEEN SLOWER THAN THE GFS...FAVORING OVERNIGHT THU AS OPPOSED TO THE EVE FOR INFLUENCE OVER OUR AREA. BOTH MODELS WOULD STILL SUPPORT SNOW CHANCES...BUT THE EC IS BETTER LOOKING FOR THAT WITH SLIGHTLY DEEPER HEIGHT FALLS AND GREATER MIXING RATIOS ON THE LIFTING SURFACES / 2.5-3 G/KG /. UNFORTUNATELY...THIS WAVE IS ONE OF MANY IN THE NORTHERN PACIFIC RIGHT NOW AND THUS NOT WELL SAMPLED. SO HAVE KEPT POPS ONLY AT A CHANCE BUT HAVE INCREASE VALUES. BEYOND...THE PROGRESSIVE PATTERN CONTINUES WITH AN IMMEDIATE INCREASE IN HEIGHTS AND A LOW-LEVEL THERMAL RIDGE INTO THE AREA. THE GFS...EC...AND GEM ALL BRING 850 MB TEMPERATURES TO ABOVE 8C ON SATURDAY. BIAS-CORRECTED FORECASTS FROM THESE MODELS BLENDED TOGETHER YIELDS HIGHS FROM THE UPPER 40S TO A STAGGERING MID 50S. WITH SUCH A QUICK TURNAROUND FROM COOL AIR ADVECTION BEHIND THE WAVE THURSDAY NIGHT/EARLY FRIDAY...WILL NOT BE GOING THAT HIGH. BUT HAVE BLENDED THE GOING FORECAST ALMOST 50 PERCENT WITH THESE. THIS AMPLIFIED PATTERN WHICH BRINGS IN THE WARMER REGIME IS AHEAD OF A DIGGING JET TO START THE NEW YEAR WHICH HAS BEEN HINTED AT IN SOLUTIONS FOR A WHILE. THIS WOULD AT LEAST BRING TEMPERATURES DOWN FOR EARLY NEXT WEEK...BUT CONFIDENCE IS LOW IN THIS AS WELL AS THE PRECIP CHANCES WITH THE SYSTEM EVOLVING ON THE JET UNDULATION. LOOKING INTO NEXT WEEK...DESPITE THE CHANCES FOR COOLER TEMPERATURES INITIALLY...THE 8 TO 14 DAY CPC OUTLOOK AND ESPECIALLY THE NAEFS MEMBERS FAVOR ABOVE NORMAL TEMPERATURES IN GENERAL. MTF && .AVIATION... //ORD AND MDW CONCERNS...UPDATED 08Z... * LIGHT RAIN...POSSIBLY MIXED WITH LIGHT SNOW...ENDING AROUND SUNRISE. * POSSIBILITY FOR FLURRIES THIS AFTERNOON. * IFR CIGS ASSOCIATED WITH PRECIPITATION IMPROVING TO MVFR BY MID MORNING. * WIND SHIFT TO NORTHWEST MID MORNING. WIND INCREASING AND BECOMING GUSTY BY LATE MORNING AND CONTINUING INTO THIS EVENING. PAW //DISCUSSION...UPDATED 06Z... LIGHT RAIN CONTINUES TO DEVELOP/SPREAD ACROSS NORTHERN IL LATE THIS EVENING WITH THE BACK EDGE EXTENDING FROM ROUGHLY MKE TO MLI. THIS WILL SLOWLY MOVE EAST ACROSS THE TERMINALS OVERNIGHT. LOW PRESSURE CURRENTLY NEAR MEMPHIS WILL LIFT NORTH ACROSS THE OHIO VALLEY THROUGH TUESDAY MORNING. AS IT DOES...ADDITIONAL PRECIP WILL SPREAD ACROSS EASTERN IL AND NORTHWEST INDIANA...LIKELY MIXING WITH THEN BECOMING ALL SNOW. WHEN AND WHERE THIS CHANGE OVER OCCURS IS THE CHALLENGE AND TRENDS STILL SUPPORT THE BULK OF THE PRECIP REMAINING JUST SOUTHEAST OF THE TERMINALS. THUS HAVE MADE NO SIGNIFICANT CHANGES WITH PREVAILING LIGHT RAIN THROUGH THE NIGHT WITH THE POTENTIAL TO MIX WITH SNOW OVERNIGHT. CIGS STILL VFR ACROSS THE AREA BUT MVFR CIGS DEVELOPING ACROSS CENTRAL IL AND AS LIGHT RAIN CONTINUES TO FALL...EXPECT CIGS TO GRADUALLY LOWER INTO MVFR. CONFIDENCE OF EXACTLY WHEN CIGS LOWER TO MVFR IS NOT PARTICULARLY HIGH...LIKELY IN THE 08Z-11Z TIME PERIOD...AND THIS WILL LIKELY NEED TWEAKING WITH OVERNIGHT UPDATES. IFR CIGS STILL POSSIBLE AND MOST LIKELY AFTER SUNRISE AS PRECIP ENDS...BUT AHEAD OF AN APPROACHING COLD FRONT. THIS FRONT SHOULD HELP LIFT ANY IFR CIGS BACK TO MVFR BY MID/LATE MORNING. ONCE WINDS SHIFT TO THE NORTHWEST...SPEEDS/GUSTS SHOULD STEADILY INCREASE AND WITH A PUSH OF COLDER AIR BY EARLY AFTERNOON...COULD BE SOME FLURRIES OR SNOW SHOWERS. SKIES BEGIN TO CLEAR BY LATE AFTERNOON/EARLY EVENING...AS WINDS ALSO BEGIN TO DIMINISH. CMS //ORD AND MDW CONFIDENCE...UPDATED 08Z... * MEDIUM CONFIDENCE IN TIMING OF PRECIPITATION ENDING THIS MORNING. * MEDIUM CONFIDENCE IN FLURRIES THIS AFTERNOON. * MEDIUM CONFIDENCE IN TIMING OF IFR CIG IMPROVEMENT. * HIGH CONFIDENCE IN WIND TREND. PAW //OUTLOOK FOR ORD/MDW FOR 12Z WEDNESDAY-12Z MONDAY...UPDATED 00Z... * WEDNESDAY...VFR. * THURSDAY...VFR. SLIGHT CHANCE OF LIGHT RAIN...POSSIBLY MIXING WITH LIGHT SNOW. * FRIDAY...MVFR POSSIBLE. SLIGHT CHANCE OF LIGHT RAIN OR LIGHT SNOW. * SATURDAY...VFR. * SUNDAY..SLIGHT CHANCE OF LIGHT RAIN OR LIGHT SNOW. CMS && .MARINE... 235 AM CST AN AREA OF LOW PRESSURE CONTINUES TO SLOWLY MOVE EAST ACROSS SOUTHERN ONTARIO THIS MORNING. DRAPED SOUTH FROM THIS LOW AND SPANNING MUCH OF THE UPPER AND MIDDLE MISSISSIPPI VALLEY IS A COLD FRONT THAT WILL SLIDE ACROSS THE LAKE LATER THIS MORNING. AHEAD OF IT...THE 15 TO 25 KT WINDS WILL VEER TO THE WEST AND THEN TO THE NORTHWEST THROUGH THE EARLY AFTERNOON HOURS. THE STRONGEST SURGE OF COLD AIR IS NOT ANTICIPATED TO BE UNTIL THE LATER AFTERNOON HOURS FOR THE NORTHERN HALF OF THE LAKE...AND SHORTLY THEREAFTER FOR THE SOUTHERN HALF. IT IS WITH THIS SURGE THAT THE STRONGEST OF WINDS IS ANTICIPATED. HIGH END GALES ARE AGAIN LIKELY...BUT FOR THE ENTIRE SPAN OF THE LAKE WITH THIS EVENT AS OPPOSED TO THE STRONGEST WINDS REMAINING NORTH YESTERDAY. FORECAST SOUNDINGS ARE ALSO INDICATING THE POTENTIAL FOR LOW END STORM FORCE GUSTS. FEEL THAT THE MAJORITY OF THE WINDS WILL REMAIN BELOW STORM CRITERIA FOR THE OPEN WATERS AND WILL ONLY MENTION IN AN OCCASIONAL GROUP. THOUGHTS THEN TURN TO LMZ745 AND 744...AND POTENTIALLY 743 AND GALES. WITH THE STRONG NORTHWESTERLY WINDS EXPECTED...INCREASES THE CHANCES INTO THE EVENING HOURS AND OVERNIGHT. WILL ERR ON THE SIDE OF CAUTION FOR THE FRICTIONLESS MARINE LOCATIONS AND CANCEL THE SMALL CRAFT FOR THOSE LOCATIONS AND HOIST A GALE WARNING. CONDITIONS SET TO IMPROVE LATE TONIGHT AS RIDGING ACROSS THE SURFACE BUILDS...THOUGH PROLONGED STRONG SOUTHWESTERLY FLOW WILL SLOWLY RAMP UP THROUGH WEDNESDAY NIGHT...WITH FLOW PROGGED TO REMAIN BELOW GALE. SHEA && .LOT WATCHES/WARNINGS/ADVISORIES... IL...NONE. IN...NONE. LM...GALE WARNING...LMZ080-LMZ261-LMZ362-LMZ364-LMZ366-LMZ563-LMZ565- LMZ567-LMZ669-LMZ671-LMZ673-LMZ675-LMZ777-LMZ779-LMZ868- LMZ870-LMZ872-LMZ874-LMZ876-LMZ878...NOON TUESDAY TO 3 AM WEDNESDAY. SMALL CRAFT ADVISORY...NEARSHORE WATERS UNTIL 6 PM WEDNESDAY. && $$
AREA FORECAST DISCUSSION
NWS GOODLAND KS
242 AM MST TUE DEC 27 2011 .SYNOPSIS... CURRENT SATELLITE IMAGERY AND RUC UPPER AIR ANALYSIS SHOW A HIGH PRESSURE OVER THE SOUTHWEST CONUS...WITH A SHORT WAVE TROUGH AND MID LEVEL MOISTURE MOVING AROUND THE NORTHERN PERIPHERY OF THE HIGH ALONG THE US/CANADIAN BORDER. OVER THE CENTRAL PLAINS A SHORT WAVE TROUGH IN THE NORTHWEST FLOW WAS PRODUCING A FEW CLOUDS. CLOSER TO HOME A SURFACE HIGH PRESSURE WAS BUILDING INTO THE TRI-STATE AREA. LATEST REPORTS OF SNOW DEPTH SHOW 2 TO 10 INCHES STILL ON THE GROUND FOR AREAS OF CENTRAL AND SOUTHWEST KANSAS...SO AM EXPECTING THIS TO HAVE A COOLING EFFECT ON TEMPERATURES THROUGH THE PERIOD. JTL && .SHORT TERM (TODAY-THURSDAY)... 228 AM MST TUE DEC 27 2011 TEMPERATURES WILL BE THE MAIN CONCERN FOR THIS PERIOD. SURFACE HIGH PRESSURE WILL MOVE ACROSS THE TRI-STATE AREA TODAY...PRECEDING A SURFACE AND UPPER LEVEL TROUGH THAT WILL MOVE THROUGH DURING THE EVENING HOURS. MODELS HAVE REDUCED THE AMOUNT OF MOISTURE AND LIFT WITH THE TROUGH PASSAGE...SO WILL FOLLOW PREVIOUS SHIFT AND KEEP OUT ANY MENTION OF PRECIPITATION. HIGH TEMPERATURES A BIT TRICKY DUE TO THE COMBINED EFFECTS OF CLOUD COVER AND SOUTHERLY WINDS BRINGING IN COOLER AIR FROM THE SNOW FIELD...BUT OVERALL TEMPERATURES TODAY WILL BE COOLER THAN YESTERDAY. LOWS TONIGHT WILL BE A FEW DEGREES WARMER THAN LAST NIGHT. WEDNESDAY MINOR RIPPLES WILL MOVE THROUGH THE UPPER LEVEL FLOW OVER THE AREA...PRODUCING A FEW CLOUDS AT BEST. WITH WESTERLY WINDS BRINGING IN WARMER AIR...TEMPERATURES WILL BE WARMER THAN TUESDAY. THURSDAY A MINOR SHORT WAVE TROUGH AND SOME MOISTURE MOVE THROUGH THE UPPER LEVEL FLOW OVER THE AREA. THIS TROUGH WILL HAVE MORE LIFT WITH IT...BUT WILL HAVE THE BEST LIFT BELOW THE MOISTURE. AS SUCH WILL LEAVE OUT A MENTION OF ANY PRECIPITATION AS THE TROUGH MOVES THROUGH. AT THE SURFACE WINDS WILL BECOME NORTHWEST BEHIND THE TROUGH AND STRENGTHEN SOME...WITH THE STRONGER WINDS OVER THE NEBRASKA COUNTIES. TEMPERATURES WILL CONTINUE THE WARMING TREND. 850MB TEMPERATURES WARM TO NEAR 10C DURING THE DAY...SO WENT WITH THE WARMER GUIDANCE SINCE 850MB TEMPERATURES OF 3C YESTERDAY AND NORTHWEST WINDS PRODUCED HIGHS AROUND 50 DEGREES...SO HIGHS AROUND 60 ARE NOT OUT OF THE QUESTION. JTL .LONG TERM (FRIDAY-MONDAY)... 228 AM MST TUE DEC 27 2011 LONG RANGE MODELS CONTINUE TO SHOW WEAK SHORT WAVE TROUGHS MOVING ACROSS THE HIGH PLAINS IN PSEUDO ZONAL FLOW THROUGH THE WEEKEND. THE STRONGEST WAVE IS DUE SATURDAY AFTERNOON OR SATURDAY NIGHT DEPENDING ON MODEL PREFERENCE...BUT MOISTURE APPEARS LIMITED REGARDLESS SO WILL KEEP FORECASTS DRY. WARM AIR ADVECTION AND ABOVE NORMAL 500 MB HEIGHTS SUPPORT DECENT WARM/UP BETWEEN THE SHORT WAVES...ESPECIALLY FRIDAY WHEN 850 MB TEMPERATURES ARE PROGGED TO REACH BETWEEN 12-14 DEGREES CELSIUS. AGREE WITH SURROUNDING OFFICES TO INCREASE MAXIMUM TEMPERATURE FORECASTS THAT DAY. EVEN WITH WARM AIR ADVECTION...TEMPERATURES SOUTH OF INTERSTATE 70 WILL BE DEPENDENT ON THE AMOUNT OF SNOW PACK MELTING THAT OCCURS BETWEEN NOW AND FRIDAY. EXPECT ENOUGH MELTING TO ALLOW TEMPERATURES TO FINALLY REACH INTO THE 50S THERE BY FRIDAY. && .AVIATION... 338 PM MST MON DEC 26 2011 WINDS WILL BEGIN TO SWITCH FROM THE NORTHWEST TO SOUTHWEST OVERNIGHT AND THROUGH THE DAY TUESDAY WITH SPEEDS ALSO DECREASING. AS AN UPPER LEVEL TROUGH APPROACHES THE REGION ON TUESDAY...MID/HIGH CLOUDS WILL INCREASE. TOWARDS TUESDAY EVENING...A SURFACE TROUGH WILL PUSH THROUGH...SWITCHING WINDS BACK TO THE NORTHWEST. BAS && .GLD WATCHES/WARNINGS/ADVISORIES... KS...NONE. NE...NONE. CO...NONE. && $$
AREA FORECAST DISCUSSION...UPDATED AVIATION
NWS ST LOUIS MO
1152 PM CST MON DEC 26 2011 .DISCUSSION... /240 PM CST MON DEC 26 2011/ RAIN IS OVERSPREADING THE AREA FROM THE SOUTH...MORE OR LESS ON TIME THIS AFTERNOON. HAVE HAD A FEW REPORTS OF A LITTLE SLEET MIXED IN WITH THE RAIN...BUT THE SLEET IS MELTING VERY QUICKLY AND SHOULD HAVE NO IMPACT. THE MAIN SLUG OF MOISTURE IS JUST MOVING UP INTO SOUTHERN MISSOURI FROM ARKANSAS AND LIKELY TO CATEGORICAL POPS STILL LOOK VERY GOOD FOR MUCH OF EASTERN MISSOURI AND SOUTHERN ILLINOIS. HOWEVER...LATEST GUIDANCE CONTINUES TO LOOK IFFY FOR MUCH SNOW. TOP-DOWN METHOD ON BUFKIT SOUNDINGS FROM THE NAM...GFS...LOCAL WRF...AND THE RUC SHOW THAT BY THE TIME THE LOWER ATMOSPHERE COOLS ENOUGH TO SUPPORT SNOW...THE TROF WILL BE LIFTING OUT AND AWAY FROM THE REGION AND DRY AIR WILL BE POURING IN ALOFT. CAN`T ENTIRELY RULE OUT SNOW SINCE TIMING THE DRY AND COLD AIR WILL BE CRITICAL...BUT HAVE REDUCED ACCUMULATIONS BELOW 1 INCH...AND HAVE CHANGED WORDING FROM LIKELY TO CATEGORICAL RAIN/SNOW...TO RAIN AND A CHANCE OF SNOW. CARNEY SRN STORM SYSTEM WILL BE NEARLY BY THE FA BY TUESDAY MORNING...AND BY THIS TIME...WILL BE AN OPEN WAVE. CONSIDERING HOW THERE IS NOT MUCH COLD AIR WITH THIS SYSTEM TO BEGIN WITH (N.B. COLD AIR HAS BEEN HARD TO COME BY SO FAR THIS LATE AUTUMN AND WINTER) AND SFC TEMPS WILL BE IN THE MID 30S...SNOW AS A GENERAL RULE WILL BE HARD TO COME BY. MODEL SOUNDINGS FROM ALL GUIDANCE SUGGESTS THIS AS WELL... ALTHOUGH WBZ VALUES AT ITS LOWEST POINT EARLY TUESDAY MORNING WILL NOT BE TOO FAR OFF FROM BEING ABLE TO RESULT IN SNOW. SO FOR THIS REASON...TO INCORPORATE A SMALL AMOUNT OF POTENTIAL MODEL ERROR... HAVE RETAINED MENTION OF SNOW...BUT AS A MIX WITH RAIN THROUGHOUT THE CONCLUSION OF THIS EVENT. ANY ADDITIONAL SNOW AMOUNTS TUESDAY MORNING WILL BE A DUSTING OR LESS AS IT LOOKS AT THIS TIME. NRN STREAM STORM SYSTEM THAT WILL BE RIGHT ON THE HEELS OF THE SRN STORM WILL PRODUCE NOTHING MORE THAN SOME ADDITIONAL CLOUDS. ANOTHER WEAK UPPER LEVEL SYSTEM WILL SLIDE THRU LATE TUESDAY NIGHT AND WEDNESDAY MORNING BUT WILL CARRY LITTLE MOISTURE WITH IT AND WILL BE TOO WEAK TO PRODUCE ANY PCPN. MOS BLENDS LOOK REASONABLE FOR MAX TEMPS TUESDAY AND WEDNESDAY. WENT AT OR ABOVE THE WARMEST MOS TEMPS FOR MINS WEDNESDAY NIGHT WITH FAIRLY STOUT SW FLOW THAT SHOULD CARRY INTO A PRETTY MILD DAY ON THURSDAY AS TEMPS SURGE INTO THE 50S. A RATHER PROGRESSIVE FLOW WILL DOMINATE THE MEDIUM RANGE FRIDAY THRU MONDAY AND WILL SIGNAL NO BIG COLD AIR OUTBREAKS (STILL) THRU THE BEGINNING OF 2012. UPPER LEVEL DISTURBANCES WILL RACE THRU AND EDGE THE FA LATE FRIDAY AND LATE SATURDAY BUT LIKE THEIR PREDECESSORS SHOULD BE TOO WEAK TO GENERATE MUCH PCPN THRU SATURDAY. BY EARLY NEXT WEEK...MOST MODELS TAKE A MUCH STRONGER SYSTEM INTO THE AREA. THE GFS IS THE EXCEPTION KEEPING THIS SYSTEM WELL TO THE N. HAVE SLIGHT CHC POPS FOR NOW UNTIL WE CAN GET SOME BETTER RUN-TO-RUN CONSISTENCY. TEMPS WILL BE AT OR ABOVE AVERAGE THRU THE PERIOD. TES && .AVIATION... /1132 PM CST MON DEC 26 2011/ N STREAM SHORTWAVE HAS BEGUN TO OPEN UP CUTOFF LOW OVER AR...AND AT THE SAME TIME THE PHASING OF ENERGY BETWEEN THESE TWO SYSTEMS HAS CAUSED PRECIP TO "FLARE UP" ONCE AGAIN OVER THE LAST 90 MINUTES FROM THE OZARKS INTO W CENTRAL IL. IFR CONDITIONS RAPIDLY OVERSPREAD THE AREA DURING THE MID AND LATE EVENING...EVEN OUTSIDE OF THE W FRINGES OF THE MORE STEADY PRECIP AT COU AND UIN. IT APPEARS THAT RAIN THREAT WILL BE ENDING BETWEEN 06-07Z AT COU AND UIN...AND NEPHANALYSIS INDICATES W EDGE OF WIDESPREAD IFR CONDITIONS ARE NOT ALL THAT FAR AWAY FROM THESE STATIONS...SO ONCE WIND SHIFT OCCURS BETWEEN 08-09Z EXPECT A FAIRLY RAPID IMPROVEMENT AND VFR CONDITIONS SHOULD RETURN BEFORE DAYBREAK. ARRIVAL OF COLDER AIR AND DEEP MIXING WILL PRODUCE STRONG NORTHWEST WINDS FROM LATE MORNING AND INTO MID AFTERNOON...WITH GUSTS IN THE 25-30KT RANGE. SPECIFICS FOR KSTL...EXTRAPOLATION OF BACK EDGE OF RADAR ECHOES SUGGESTS PRECIP WILL PERSIST THROUGH 10-11Z IN THE STL AREA...AND GIVEN LATEST ACARS AND 00Z FORECAST SOUNDINGS SNOW IS BECOMING A BIT MORE OF A CONCERN. HAVE STARTED OFF NEW TAFS WITH A MIX...AND GONE TO ALL SNOW BY 08Z...WITH IFR CIGS AND MVFR/OCNL IFR VSBYS HOLDING THROUGHOUT THE PREDAWN HOURS. MUCH LIKE COU AND UIN...FORECAST SOUNDINGS SUGGEST A FAIRLY RAPID IMPROVEMENT IN CIGS TUESDAY MORNING WHEN WIND SHIFT OCCURS...AND HAVE CONTINUED EARLIER TRENDS IN FORECASTING RETURN OF VFR CONDITINS IN THE 14-15Z TIME FRAME. NORTHWEST WINDS WILL RAMP UP FAIRLY QUICKLY LATE TUESDAY MORNING AS COLDER AIR BEGINS TO DROP INTO REGION...AND EXPECTING GUSTS NEAR 30 KTS DURING THE AFTERNOON. TRUETT && .LSX WATCHES/WARNINGS/ADVISORIES... MO...NONE. IL...NONE. && $$ WFO LSX
AREA FORECAST DISCUSSION
NWS BINGHAMTON NY
445 AM EST TUE DEC 27 2011 .SYNOPSIS... A LOW PRESSURE SYSTEM WILL IMPACT THE AREA WITH MAINLY RAIN THIS AFTERNOON THROUGH EVENING...FOLLOWED BY WINDY AND MUCH COLDER CONDITIONS WITH SNOW SHOWERS INTO WEDNESDAY. BRIEF HIGH PRESSURE IS EXPECTED WEDNESDAY NIGHT TO EARLY THURSDAY...BUT AN UNSETTLED PATTERN WITH OCCASIONAL PASSING DISTURBANCES CAN BE EXPECTED LATE THURSDAY THROUGH THE WEEKEND. && .NEAR TERM /THROUGH TONIGHT/... 10PM UPDATE...WITH CLEAR SKIES AND THE SYSTEM NOT COMING IN UNTIL THE AFTERNOON, THE WEATHER IS QUIET. MADE LITTLE CHANGES THROUGH TOMORROW MORNING. THEN, THE ONLY CHANGES WAS TO TIMING AND SOME QPF AMOUNTS. WENT MUCH CLOSER TO HPC AMOUNTS FOR THIS SYSTEM. OTHERWISE, NO SIGNIFICANT CHANGES TO THE FORECAST. PREVIOUS DISCUSSION...VIS SATL IMAGERY SHOWS SC LAYER OVER ALL OF C NY AND NE PA. LARGE SCALE SUBSC BEHIND DEPARTING SHRT WAVE OFF THE NE COAST WILL CONT TO PUSH INVERSION DOWN AND EVENTUALLY WILL LEAD TO CLRG SKIES LATE THIS AFTERNOON AND ERLY EVENING. VIS SATL IMAGERY ALREADY SHOWG THIS IN WRN NY AND NC/NE PA. THE BACK EDGE OF THE SC LAYER CORRELATED WELL WITH THE 850 MB TEMP GRADIENT WHICH IS INDICATIVE OF THE SUBSC. USING THE LOCAL WRFARW...THIS GRADIENT MOVES THRU BTWN 21Z AND 00Z...WHILE THE RUC13 HOLDS ONTO THE COLDER H85 TEMPS IN EC NY A LITTLE LONGER. IN ANY EVENT BOTH SEEM TO SHOW SIGNS THAT THIS CLRG WILL TAKE A BIT LONGER IN EC NY...WHERE THERE IS HIGHER TERRAIN. THIS MAKES SENSE AND WILL HOLD ONTO CLDS A LITTLE LONGER IN THESE AREAS. REST OF AREA SEES CLRG FOR A TIME THIS EVENING. AFTER THE CLDS CLEAR OUT THIS EVENING...HIGHER CLDS FROM THE NEXT SYSTEM BEGIN TO SPREAD ACROSS NY AND PA. THE SFC RDG AXIS IS E OF THE REGION TONIGHT AS THE NEXT SYSTEM RAPIDLY APPRCHES FROM THE SRN PLAINS AND UPR MIDWEST. THE LL FLO WILL TURN SWRLY AND SHUD KEEP TEMPS FROM BOTTOMING OUT MUCH BELOW 30 MOST PLACES. THE EXCEPTION IS IN NE PA/SERN NY WHERE THE WINDS WILL REMAIN LIGHT ENUF WITH CLR SKIES. THUS MINS WILL BE HIGHER IN THE NW CWA LOW 30S AND LOWER IN THE SE CWA MID TO UPPER 20S OR SO. FOR TUESDAY...CLDS WILL INCREASE THRU THE DAY AS STRG WAA/ISEN LIFT TAKES PLACE THRU A DEEPER AND DEEPER LAYER AS THE DAY PROGRESSES. TEMPS FROM THE SFC THRU 850 MB WILL BE WARM ENUF FOR ALL RAIN ENTIRE CWA. ALL SYNOPTIC SCALE MODELS INDICATE THAT THE RAIN WILL MOVE IN DURING THE AFTERNOON. WILL RAMP POPS UP BTWN 18Z TUE AND 00Z WED. && .SHORT TERM /WEDNESDAY THROUGH THURSDAY/... MAIN CONCERN IS FOR STRONG GUSTY WINDS WEDNESDAY...WITH ACCUMULATING LAKE EFFECT SNOW SHOWERS. STRONG COLD AIR ADVECTION WILL BE UNDERWAY WEDNESDAY...WITH FALLING TEMPERATURES EXPECTED THROUGH THE DAY. IT WILL UNDOUBTEDLY FEEL LIKE A REALITY CHECK THAT IT IS INDEED LATE DECEMBER. SOUNDINGS SUGGEST MIXING TO ABOUT THE 875 MB LEVEL...WITH MODELS AGREEING THAT WINDS WILL BE IN THE 35-40 KT RANGE AT THE TOP OF THAT MIXING LAYER. CONVECTIVE OVERTURNING OF THE BOUNDARY LAYER...WILL MANAGE TO BRING A GOOD AMOUNT OF THOSE WINDS TO THE SURFACE. I HAVE INCREASED GUSTS TO 35-45 MPH RANGE FOR MAJORITY OF THE AREA...STRONGEST AT HIGHER ELEVATIONS SUCH AS THE CATSKILLS. THIS ALONG WITH FALLING TEMPERATURES...WILL BRING WIND CHILLS INTO THE SINGLE DIGITS WEDNESDAY AFTERNOON. AS FOR LAKE EFFECT SNOW...A GOOD CHUNK OF THE 850-925 MB LAYER WILL SHOVE QUICKLY INTO DENDRITIC GROWTH TEMPERATURE RANGE...MINUS-12 TO MINUS-18 CELSIUS. BECAUSE THERE WILL BE MOISTURE STILL TRAPPED UNDER THE INVERSTION...A MAJORITY OF THE AREA SHOULD SEE SOME SNOW SHOWERS WITH COLD AIR ADVECTION OF THIS MAGNITUDE. HOWEVER...SPEED OF WINDS WILL LIMIT RESIDENCE TIME OVER THE LAKE...ESPECIALLY SINCE THE DIRECTION WILL BE FROM 290-300 VERSUS 270-280 WHICH WOULD BE DOWN THE LONG AXIS. ALSO...THE AIR MASS THAT IS MOVING IN IS QUITE DRY...WITH DEW POINTS FALLING THROUGH THE TEENS IN THE AFTERNOON. THOSE TWO FACTORS...ALONG WITH SOME DIRECTIONAL SHEAR...WILL LIMIT ACCUMULATIONS SOMEWHAT. AT THIS TIME...EXPECTING IT TO RANGE FROM AN INCH OR TWO IN THE TWIN TIERS TO 3-4 INCHES OR SO TO THE NORTH. MESOSCALE BANDING OF COURSE COULD CAUSE LOCALIZED HIGHER AMOUNTS. THE COMBINED SNOW...WIND...AND WIND CHILL MAY NECESSITATE A WINTER WEATHER ADVISORY. ALSO OF CONCERN...IS THAT IF THERE ARE ANY UNTREATED ROADS STILL WET EARLY WEDNESDAY MORNING...COULD UNDERGO A QUICK FREEZE AND TEMPERATURES CONTINUE TO PLUMMET DURING THE DAY. HOPEFULLY THE INCREASED WIND WILL FIRST DRY IT UP. WEDNESDAY NIGHT...WINDS SUBSIDE AND LINGERING LAKE EFFECT SNOW SHOWERS DIMINISH...AS HIGH PRESSURE AND VERY DRY AIR MASS TAKE CHARGE. && .LONG TERM /THURSDAY NIGHT THROUGH MONDAY/... FORECAST ADJUSTED TO ACCOUNT FOR LATEST MODEL INFORMATION WHERE NEEDED...INCLUDED THE COOLING OF SOME TEMPERATURES. OVERALL PATTERN REMAINS THE SAME...WITH SEVERAL SMALL DISTURBANCES/CLIPPERS BRINGING OCCASIONAL CHANCES OF SNOW OR RAIN. PREVIOUS DISCUSSION... THE LONG TERM WILL BE DOMINATED BY A BRISK WEST TO EAST FLOW, AS THE STRONGLY POSITIVE PNA PATTERN RELAXES. THE RESULT WILL BE A SERIES OF CLIPPERS AND FAST MOVING SYSTEMS TRAVERSING THE GREAT LAKES AND SOUTHERN ONTARIO PROVINCE. HOWEVER BY LATE IN THE PERIOD, A JET WILL DIVE INTO THE PLAINS AND CARVE OUT ANOTHER DEEP TROUGH OVER THE WEST-CENTRAL UNITED STATES. THIS WILL CAUSE THE POSITIVE PNA PATTERN TO BEGIN TO STRENGTHEN AGAIN, WITH RISING HEIGHTS INTO THE EASTERN CONUS. AS A RESULT, WE ARE FORECASTING LOW POP, BRIEF DURATION RW/SW EVENTS WITH LITTLE ACCUMULATION ANTICIPATED. WE ARE ALSO FORECASTING TEMPERATURES SLIGHTLY ABOVE NORMAL FOR THE THURSDAY TO MONDAY PERIOD. && .AVIATION /09Z TUESDAY THROUGH SATURDAY/... SCATTERED HIGH CIRRUS AND LIGHT WINDS DURING THE REMAINDER OF OVERNIGHT...INTO EARLY TUESDAY MORNING. HIGH CLOUDS THICKEN AND LOWER SOMEWHAT 14Z ONWARD...YET STILL EASILY VFR. HOWEVER...SYSTEM ENTERS THE AREA AND QUICKLY DETERIORATES CONDITIONS SOUTHWEST TO NORTHEAST WITH SHIELD OF RAIN AND MVFR LOWERING TO IFR FOR MOST AREAS. WET SNOW MAY BRIEFLY OCCUR AT ONSET OF PRECIPITATION FOR KBGM AND KRME AROUND 19Z-21Z...BUT OTHERWISE WILL JOIN OTHER TERMINALS WITH PLAIN RAIN AND LIKELY IFR. DEEPENING SURFACE LOW ITSELF PASSES THROUGH 00Z-03Z WEDNESDAY...WITH ABRUPT SHIFT IN WIND TO WSW AND STARTING TO INCREASE /THOUGH STRONGER GUSTS WILL WAIT UNTIL AFTER 06Z WEDNESDAY/. RAIN SHOWERS WILL GET LIGHTER 03Z-06Z WEDNESDAY...YET WILL ALSO START CHANGING OVER TO SNOW. .OUTLOOK... WED...MVFR/OCCASIONAL IFR IN SNOW SHOWERS...ESPECIALLY IN MORNING. STRONG WEST TO WNW WINDS WITH GUSTS REACHING AT LEAST 25-35 KTS. WED NGT/THU...VFR. FRI/SAT...MAINLY VFR. POSSIBLE MVFR IN BRIEF SNOW SHOWERS. && .BGM WATCHES/WARNINGS/ADVISORIES... PA...NONE. NY...NONE. && $$ SYNOPSIS...MLJ/MDP NEAR TERM...DJN/SLI SHORT TERM...MDP LONG TERM...DJP/MDP AVIATION...MDP
AREA FORECAST DISCUSSION
NWS BINGHAMTON NY
1248 AM EST TUE DEC 27 2011 .SYNOPSIS... SOUTHERLY FLOW AHEAD OF A LOW PRESSURE SYSTEM WILL BRING MILDER TEMPERATURES TO THE AREA TOMORROW. RAIN WILL MOVE INTO THE AREA TUESDAY AFTERNOON. THERE WILL BE A CHANGE OVER TO SNOW LATE TUESDAY NIGHT AS COLDER AIR MOVES BACK IN. LAKE EFFECT SNOW IS POSSIBLE ON WEDNESDAY. HIGH PRESSURE WILL BUILD IN THURSDAY. && .NEAR TERM /THROUGH TODAY/... 10PM UPDATE...WITH CLEAR SKIES AND THE SYSTEM NOT COMING IN UNTIL THE AFTERNOON, THE WEATHER IS QUIET. MADE LITTLE CHANGES THROUGH TOMORROW MORNING. THEN, THE ONLY CHANGES WAS TO TIMING AND SOME QPF AMOUNTS. WENT MUCH CLOSER TO HPC AMOUNTS FOR THIS SYSTEM. OTHERWISE, NO SIGNIFICANT CHANGES TO THE FORECAST. PREVIOUS DISCUSSION...VIS SATL IMAGERY SHOWS SC LAYER OVER ALL OF C NY AND NE PA. LARGE SCALE SUBSC BEHIND DEPARTING SHRT WAVE OFF THE NE COAST WILL CONT TO PUSH INVERSION DOWN AND EVENTUALLY WILL LEAD TO CLRG SKIES LATE THIS AFTERNOON AND ERLY EVENING. VIS SATL IMAGERY ALREADY SHOWG THIS IN WRN NY AND NC/NE PA. THE BACK EDGE OF THE SC LAYER CORRELATED WELL WITH THE 850 MB TEMP GRADIENT WHICH IS INDICATIVE OF THE SUBSC. USING THE LOCAL WRFARW...THIS GRADIENT MOVES THRU BTWN 21Z AND 00Z...WHILE THE RUC13 HOLDS ONTO THE COLDER H85 TEMPS IN EC NY A LITTLE LONGER. IN ANY EVENT BOTH SEEM TO SHOW SIGNS THAT THIS CLRG WILL TAKE A BIT LONGER IN EC NY...WHERE THERE IS HIGHER TERRAIN. THIS MAKES SENSE AND WILL HOLD ONTO CLDS A LITTLE LONGER IN THESE AREAS. REST OF AREA SEES CLRG FOR A TIME THIS EVENING. AFTER THE CLDS CLEAR OUT THIS EVENING...HIGHER CLDS FROM THE NEXT SYSTEM BEGIN TO SPREAD ACROSS NY AND PA. THE SFC RDG AXIS IS E OF THE REGION TONIGHT AS THE NEXT SYSTEM RAPIDLY APPRCHES FROM THE SRN PLAINS AND UPR MIDWEST. THE LL FLO WILL TURN SWRLY AND SHUD KEEP TEMPS FROM BOTTOMING OUT MUCH BELOW 30 MOST PLACES. THE EXCEPTION IS IN NE PA/SERN NY WHERE THE WINDS WILL REMAIN LIGHT ENUF WITH CLR SKIES. THUS MINS WILL BE HIGHER IN THE NW CWA LOW 30S AND LOWER IN THE SE CWA MID TO UPPER 20S OR SO. FOR TUESDAY...CLDS WILL INCREASE THRU THE DAY AS STRG WAA/ISEN LIFT TAKES PLACE THRU A DEEPER AND DEEPER LAYER AS THE DAY PROGRESSES. TEMPS FROM THE SFC THRU 850 MB WILL BE WARM ENUF FOR ALL RAIN ENTIRE CWA. ALL SYNOPTIC SCALE MODELS INDICATE THAT THE RAIN WILL MOVE IN DURING THE AFTERNOON. WILL RAMP POPS UP BTWN 18Z TUE AND 00Z WED. && .SHORT TERM /TONIGHT THROUGH WEDNESDAY NIGHT/... THE 12Z EURO...18Z NAM...12Z GFS HAVE TRENDED MORE TOWARD THE WEST WITH THE SFC LO AND ALL INDICATE THAT THE 850 MB LOW TRACKS TO WRN NY BY 00Z WED. THIS WILL ALLOW 850 MB TEMPS TO CLIMB WELL ABV FRZG AS THE PRECIP WORKS IN. WITH BNDRY LAYER TEMPS EXPECTED ABV FRZG...PRECIP WILL BE MAINLY RAIN AT THE ONSET. IN ADDTN...WITH THIS MORE WRN TRACK...THE DRY SLOT WITH THE DEVELOPING CYCLONE MOVES RIGHT THRU NE PA AND C NY TUE EVE. COLDER AIR DOES NOT SURGE IN UNTIL THE BULK OF THE MOISTURE AND LIFT WITH THE STORM IS NE OF OUR AREA. THUS...IT LOOKS LIKE A RAIN EVENT...POSSIBLY MIXED WITH SLEET/SNOW FINGER LAKES/UPR MOHAWK/TUG HILL TUE EVE...THEN WRAP AROUND SNOW AND SNOW SHOWERS ENHANCED BY MOISTURE FROM LAKE ONTARIO TUE NGT/ERLY WED. THE SNOW SHOWERS WILL CONT WED IN C NY AS THE WRAP AROUND SNOW SHOWERS TRANSITIONS TO LAKE EFFECT SNOWS. THE INVERSION RAPIDLY DROPS DOWN TO 900 MB BY 00Z THU. THUS THERE WILL BE SOME LES...BUT IT SHUD NOT BE A MAJOR EVENT. MOST OF THE SNOW WILL FALL WED AM...IN NC NY WITH THE COMBINATION OF LAKE EFFECT AND SYNOPTIC MOISTURE. SEE 2-5 INCHES OF SNOW IN NC NY...WITH AN INCH OR LESS SC NY/FAR NRN PA AND LITTLE IF ANY IN THE REST OF NE PA. ANOTHER CONCERN IS THE POTENTIAL FOR HIGH WINDS ON WEDNESDAY AS THE DEEPENING CYCLONE DEPARTS ACRS LWR QUEBEC. MOS GUIDC SUGGESTS LOW END WIND ADVY CRITERIA. ISALLABORIC PRESSURE RISES ARE RUNNING CLOSE TO 10 MB/6 HR WHICH IS ALSO BORDERLINE FOR WIND ADVY. SO WILL HIGHLIGHT IN HWO FOR ENTIRE CWA...AND WILL HIGH POTENTIAL FOR SOME SNOW IN NC NY AS WELL. BY WED NGT...LES SNOW SHOWERS AND FLURRIES RAPIDLY COME TO AN END AS THE LL FLO TURNS MORE WRLY IN ADVANCE OF THE NEXT SYSTEM. && .LONG TERM /THURSDAY THROUGH MONDAY/... THE LONG TERM WILL BE DOMINATED BY A BRISK WEST TO EAST FLOW, AS THE STRONGLY POSITIVE PNA PATTERN RELAXES. THE RESULT WILL BE A SERIES OF CLIPPERS AND FAST MOVING SYSTEMS TRAVERSING THE GREAT LAKES AND SOUTHERN ONTARIO PROVINCE. HOWEVER BY LATE IN THE PERIOD, A JET WILL DIVE INTO THE PLAINS AND CARVE OUT ANOTHER DEEP TROUGH OVER THE WEST-CENTRAL UNITED STATES. THIS WILL CAUSE THE POSITIVE PNA PATTERN TO BEGIN TO STRENGTHEN AGAIN, WITH RISING HEIGHTS INTO THE EASTERN CONUS. AS A RESULT, WE ARE FORECASTING LOW POP, BRIEF DURATION RW/SW EVENTS WITH LITTLE ACCUMULATION ANTICIPATED. WE ARE ALSO FORECASTING TEMPERATURES SLIGHTLY ABOVE NORMAL FOR THE THURSDAY TO MONDAY PERIOD. && .AVIATION /06Z TUESDAY THROUGH SATURDAY/... SCATTERED HIGH CIRRUS AND LIGHT WINDS DURING THE REMAINDER OF OVERNIGHT...INTO EARLY TUESDAY MORNING. HIGH CLOUDS THICKEN AND LOWER SOMEWHAT 14Z ONWARD...YET STILL EASILY VFR. HOWEVER...SYSTEM ENTERS THE AREA AND QUICKLY DETERIORATES CONDITIONS SOUTHWEST TO NORTHEAST WITH SHIELD OF RAIN AND MVFR LOWERING TO IFR FOR MOST AREAS. WET SNOW MAY BRIEFLY OCCUR AT ONSET OF PRECIPITATION FOR KBGM AND KRME AROUND 19Z-21Z...BUT OTHERWISE WILL JOIN OTHER TERMINALS WITH PLAIN RAIN AND LIKELY IFR. DEEPENING SURFACE LOW ITSELF PASSES THROUGH 00Z-03Z WEDNESDAY...WITH ABRUPT SHIFT IN WIND TO WSW AND STARTING TO INCREASE /THOUGH STRONGER GUSTS WILL WAIT UNTIL AFTER 06Z WEDNESDAY/. RAIN SHOWERS WILL GET LIGHTER 03Z-06Z WEDNESDAY...YET WILL ALSO START CHANGING OVER TO SNOW. .OUTLOOK... WED...MVFR/OCCASIONAL IFR IN SNOW SHOWERS...ESPECIALLY IN MORNING. STRONG WEST TO WNW WINDS WITH GUSTS REACHING AT LEAST 25-35 KTS. WED NGT/THU...VFR. FRI/SAT...MAINLY VFR. POSSIBLE MVFR IN BRIEF SNOW SHOWERS. && .BGM WATCHES/WARNINGS/ADVISORIES... PA...NONE. NY...NONE. && $$ SYNOPSIS...SLI NEAR TERM...DJN/SLI SHORT TERM...DJN/SLI LONG TERM...DJP AVIATION...MDP
AREA FORECAST DISCUSSION
NWS BUFFALO NY
1126 PM EST MON DEC 26 2011 .SYNOPSIS... HIGH PRESSURE CENTERED ALONG THE MIDDLE ATLANTIC COAST WILL DRIFT SLOWLY TO THE EAST OVERNIGHT. A COMPLEX DOUBLE BARRELLED STORM SYSTEM STRETCHING FROM THE UPPER GREAT LAKES TO THE TENNESSEE VALLEY WILL CONSOLIDATED INTO A SINGLE LOW OVER PENNSYLVANIA LATE TUESDAY. THIS STORM SYSTEM IS FORECAST TO LIFT TO THE SAINT LAWRENCE VALLEY BY WEDNESDAY MORNING. THIS SCENARIO WILL LEAD TO RAIN AND MIXED PRECIPITATION ACROSS OUR REGION ON TUESDAY... WITH COLDER AIR ON THE BACKSIDE OF THE STORM CHANGING ALL OF THE PRECIPITATION TO ACCUMULATING SNOW LATE TUESDAY AND TUESDAY NIGHT. && .NEAR TERM /THROUGH TUESDAY/... MAINLY CLEAR SKIES WILL GIVE WAY TO AN INCREASE IN MID AND HIGH LEVEL CLOUDS OVERNIGHT AS MOISTURE STREAMS NORTH FROM THE DEVELOPING LOWER MISSISSIPPI LOW. THE LATEST WATER IMAGERY SHOWS TWO DISTINCT SHORTWAVES. THE SHORT WAVE EMBEDDED WITHIN THE NORTHERN BRANCH OF THE JET STREAM WAS DIVING SOUTH ACROSS THE DAKOTAS WHILE THE SOUTHERN BRANCH VORT MAX WAS HEADING EAST INTO ARKANSAS. THE DEEP LAYERED SOUTHERLY FLOW BETWEEN THESE UPPER LEVEL IMPULSES AND THE EXITING HIGH PRESSURE WILL CIRCULATE INCREASED MOISTURE NORTHWARDS...WHILE ALSO DEVELOPING A WARM ADVECTIVE PATTERN. THIS SCENARIO WILL KEEP TEMPERATURES STEADY OVERNIGHT. THE VORT MAXES WILL CONVERGE ON THE UPPER OHIO VALLEY TUESDAY WHILE LOW PRESSURE CONSOLIDATES IN THE VCNTY OF EASTERN OHIO AND WESTERN PENNSYLVANIA. WHILE THIS WILL INITIALLY KEEP A SOUTHERLY WARM ADVECTIVE FLOW OVER ALL OF OUR FORECAST AREA...THE MID LEVEL WARMTH WILL GET CUT OFF DURING THE COURSE OF THE AFTERNOON AS THE CIRCULATION ALOFT (THROUGH 10K FT) IS FORECAST TO CUT OFF OVER THE WRN COUNTIES. THIS WILL COMPLICATE AN ALREADY TRICKY FORECAST. THE DYNAMICS IMPOSED BY A DIVERGENT UPPER LEVEL FLOW AND RR QUAD OF A 130KT H25 JET WILL PROMOTE WIDESPREAD PCPN ACROSS OUR AREA ON TUESDAY...WITH THE PRECIPITATION LIFTING NORTHEAST AND SPREADING ACROSS THE WESTERN COUNTIES DURING THE MORNING AND MIDDAY. AREAS EAST OF LK ONTARIO SHOULD BE PCPN FREE UNTIL EARLY TO MID AFTERNOON. WHILE SFC TEMPS WILL RANGE FROM THE UPPER 30S TO LOWER 40S ACROSS MOST OF WESTERN NEW YORK AT THE ONSET OF THE PCPN...THERMAL PROFILES FROM BOTH THE NAM AND GFS SUGGEST THAT THE COLUMN WILL BE LARGELY BELOW FREEZING ABOVE 1500 FT. NOT ONLY IS THE BULK OF THE SOUNDING FORECAST TO BE BELOW FREEZING...BUT THE LOWEST 5K FT WILL LIKELY BE ISOTHERMAL BETWEEN MINUS 2 AND MINUS 5C. MORE ON THAT IN A MOMENT. THIS SOMEWHAT UNUSUAL SOUNDING IS DUE TO A RATHER STRANGE SFC STORM TRACK...THAT TAKES THE SFC LOW FROM NEAR PIT TO ABOUT BGM THEN TO BTV. SFC STORMS USUALLY TRACK WEST OR EAST OF THE OROGRAPHIC (ALLEGANY MTNS)...BUT IN THIS CASE THE LOW IS FORECAST TO TRACK ACROSS THE TOPOGRAPHY. AS MENTIONED EARLIER...THIS WILL CUT OFF THE MID LEVEL WARMTH FAIRLY EARLY ON IN THE EVENT SO HAVE LEANED TOWARDS A `COLDER` FORECAST WITH A FASTER CHANGEOVER TO MIXED/SNOW EVENT. FOR WHAT ITS WORTH...THE SREF PCPN PLUMES FAVOR THIS SOLUTION AND ARE IN FAIRLY GOOD AGREEMENT WITH THE FORECAST SOUNDINGS FROM THE OTHER MAJOR GUIDANCE PACKAGES. QPF FOR TUESDAY WILL RANGE FROM A QUARTER INCH ACROSS THE SRN TIER TO A LITTLE MORE THAN A TENTH ELSEWHERE. THIS IS NOT SIGNIFICANT FOR THE DAYLIGHT HOURS...ALTHOUGH THE HIGHER TERRAIN OF THE SOUTHERN TIER COULD PICK UP A WET INCH OR SO OF ACCUMULATION BY NIGHTFALL. ONE WORRISOME SUBTLETY IN THE FORECAST SOUNDINGS IS THAT A FAIRLY DEEP MINUS 2 TO MINUS 5 LAYER ISOTHERMAL LAYER WILL PROMOTE MORE EFFICIENT SNOW MAKING AS AGGREGATION IN THE LOW LEVELS COULD BE SIGNIFICANT. && .SHORT TERM /TUESDAY NIGHT THROUGH WEDNESDAY/... DEEPENING LOW PRESSURE TRACKING ACROSS NEW ENGLAND WILL BRING IN COLDER AIR TUESDAY NIGHT...WHICH WILL CHANGE PRECIPITATION OVER TO SNOW. THIS WILL LIKELY BRING ACCUMULATING SNOW TO ALL OF WESTERN NEW YORK...WITH THE POSSIBILITY OF MORE SIGNIFICANT (6 INCHES OR GREATER OF SNOW) ACROSS THE SOUTHERN TIER...AND EAST OF LAKE ONTARIO. MUCH COLDER AIR WILL MOVE IN WEDNESDAY...WITH LINGERING LAKE EFFECT SNOW SHOWERS SE OF LAKE ONTARIO...AND BLUSTERY CONDITIONS DURING THE DAY...WITH WITH HIGHS ON WEDNESDAY ONLY IN THE LOWER 20S ACROSS MUCH OF THE REGION. FOR THE DETAILS...MODEL AGREEMENT HAS IMPROVED WITH THE 12Z RUNS...WITH GENERALLY A FAIRLY TIGHT CLUSTER OF SOLUTIONS AMONG THE MODELS CONSULTED. THE BIGGEST MATERIAL DIFFERENCE AMONG MODELS IS HOW QUICKLY THE LOW DEEPENS...WITH THE 12Z NAM TRENDING SLOWER THAN MOST OTHER MODELS. USING A CONSENSUS OF THE 12Z RUNS OF THE NAM/RGEM/GFS/UKMET/EUROPEAN/SREF PUTTING 985 MB SURFACE LOW ALONG THE MAINE/QUEBEC BORDER AT 12Z WEDNESDAY. DESPITE THE FAIRLY GOOD MODEL AGREEMENT...THE CHALLENGE IN THIS EVENT IS THE DETAILS. BUT TUESDAY NIGHT...FORECAST SOUNDINGS WILL BE MARGINAL FOR SNOW IN FAR WESTERN SECTIONS...AND IN JEFFERSON/LEWIS COUNTIES. RAIN/SNOW WILL DEPEND ON SUBTLE DIFFERENCES IN SURFACE TEMPERATURE...WHERE HIGHER ELEVATIONS WILL LIKELY CHANGEOVER FIRST. LATE TUESDAY NIGHT...A STRONG PSEUDO-ARCTIC BOUNDARY WILL SWEEP ACROSS AS THE LOW INTENSIFIES IN EASTERN QUEBEC. COLD AIR WITH THIS WILL DEFINITELY CHANGE PRECIPITATION OVER TO SNOW...AND IT IS THIS FEATURE WHICH WILL LIKELY BRING AN INCH OR TWO ACROSS THE REGION. ON WEDNESDAY...THIS ARCTIC BOUNDARY WILL CONTINUE TO PUSH TO THE EAST OF REGION...USHERING IN COLD DAYTIME TEMPS. WITH THE UPPER TROF STILL BACK ACROSS THE REGION...EXPECT THIS WILL SET UP A BRIEF PERIOD OF LAKE ENHANCED SNOW SE OF LAKE ONTARIO...WAYNE COUNTY EASTWARD. WINDS WILL BE A BIT ON THE STRONG SIDE...BUT WITH RAPID COOLING...LAKE INDUCED INSTABILITY WILL INCREASE TO AROUND 300 J/KG. AS THE SHORTWAVE EXITS...THIS SHOULD DRY THE AIR OUT...ALLOWING LAKE SNOWS TO TAPER OFF. A WINTER STORM WATCH WAS CONSIDERED...BUT ULTIMATELY CONFIDENCE IS NOT QUITE HIGH ENOUGH FOR THE HEADLINE. SNOW AMOUNTS ARE MARGINAL TO SUPPORT THE HEADLINE...AND WITH THE SEVERAL CLOSE CALLS WITH THIS SYSTEM...FROM THE MARGINALLY COLD AIR MASS AT THE ONSET...TO THE FRONTAL BOUNDARY SNOW SHOWERS...TO THE POSSIBLE LAKE ENHANCEMENT AT THE END. BECAUSE OF THIS...WILL HOLD OFF ON ANY HEADLINES AND CONTINUE A MENTION IN THE HWO. FOR THOSE INTERESTED IN SNOW AMOUNTS...EXPECT MOST LOCATIONS TO BE IN THE 1 TO 3 INCH RANGE. THE EXCEPTIONS ARE WESTERN PORTIONS OF THE SOUTHERN TIER...AND E-SE OF LAKE ONTARIO...ROUGHLY INCLUDING WAYNE/N CAYUGA/OSWEGO/JEFFERSON/LEWIS COUNTIES...WHERE 4 INCHES OR GREATER OF SNOW ARE LIKELY. DEPENDING ON HOW SEVERAL FACTORS WORK OUT...COULD SEE AMOUNTS TO 8 INCHES IN SOME OF THESE LOCATIONS...HOWEVER AMOUNTS THIS HIGH ARE ONLY A POSSIBILITY AT THIS TIME. THERE WILL BE OTHER IMPACTS WITH THIS SYSTEM. THE FRONTAL BOUNDARY WILL CAUSE TEMPERATURES TO DROP QUITE RAPIDLY EARLY WEDNESDAY MORNING. THIS MAY CAUSE ANY WATER OR SLUSH ON ROADWAYS TO FREEZE...POTENTIALLY MAKING FOR A SLICK COMMUTE WEDNESDAY MORNING. ALSO...THE TIMING OF THE FRONTAL BOUNDARY WILL BE KEY...AS EVEN AN INCH OR TWO OF SNOW CAN BE A NUISANCE...IF IT COMES QUICKLY AND NEAR RUSH HOUR. && .LONG TERM /WEDNESDAY NIGHT THROUGH MONDAY/... HIGH PRESSURE WILL BRIEFLY RIDGE ACROSS THE REGION WEDNESDAY NIGHT. THERE MAY BE SOME LINGERING LAKE EFFECT SNOW SHOWERS EAST OF LAKE ONTARIO...WITH THIS TO END AS WINDS SHIFT TO THE SW LATE IN THE NIGHT. THE THURSDAY THROUGH SUNDAY PERIOD WILL FEATURE A ZONAL FLOW...WITH A COUPLE OF CLIPPERS FORECAST TO CROSS THE REGION. THE 12Z GFS/EUROPEAN/GGEM DIFFER ON THE TIMING OF THESE FAST SYSTEM...MAKING POPS DIFFICULT TO BE TOO SPECIFIC. ALSO...TEMPERATURES WILL BE MARGINAL FOR LAKE EFFECT AHEAD OF THE CLIPPER. THE RESULT WILL BE ONLY MODEST LEVELS OF INSTABILITY...AND TEMPERATURES WILL AT TIMES BE MARGINALLY COLD ENOUGH FOR SNOW...WITH SOME RAIN POSSIBLE. GIVEN THE MARGINALLY COLD 850MB TEMPS...DO NOT EXPECT ANY MAJOR EVENTS FROM THESE CLIPPERS...BUT IT WILL BE HARD TO RULE OUT A RAIN OR SNOW SHOWER DURING THIS PERIOD...EVEN IF THE MAJORITY OF THE TIME WILL BE DRY. A STALLED FRONTAL BOUNDARY WILL BE CLOSE TO THE EASTERN LAKE ONTARIO REGION...SO AS THIS FLUCTUATES WITH THE SYSTEMS...IT MAY BE MARKEDLY COLDER THERE AT TIMES. ON MONDAY...THE EUROPEAN LIFTS LOW PRESSURE ACROSS THE REGION...WITH THE GFS/GGEM SHOWING MORE OF A RIDGE. NO STRONG FEELINGS EITHER WAY ON THIS...AND WILL SIMPLY MAINTAIN CHANCE POPS. && .AVIATION /06Z TUESDAY THROUGH SATURDAY/... VFR CONDITIONS WILL PREVAIL OVERNIGHT THROUGH THE FIRST HALF OF TUESDAY WITH HIGH PRESSURE CENTERED OFF THE MIDDLE ATLANTIC COAST IN CONTROL. THERE WILL BE AN INCREASE IN CLOUD THOUGH AS A DEVELOPING AREA OF LOW PRESSURE MOVES NORTHEAST TOWARD THE OHIO VALLEY. CLOUDS FROM THE APPROACHING LOW WILL LOWER AND THICKEN ON TUESDAY...WITH RAIN (MIXED WITH SNOW HIGHER ELEVATIONS) SPREADING NORTHEAST ACROSS THE STATE. THE LAST TWO RUNS OF THE NAM SUGGEST THAT THE COLDER AIR WILL ARRIVE A LITTLE SOONER...POSSIBLY RESULTING IN A RAIN/SNOW MIX AT MOST TAF SITES TOWARD MID TO LATE AFTERNOON. VFR CONDITIONS WILL LOWER MVFR TOWARD MID AFTERNOON AS LOW LEVEL MOISTURE DEEPENS AHEAD OF THE APPROACHING LOW. AS THE RAIN/SNOW MIX BECOME MORE PREVALENT LATER IN THE AFTERNOON...IFR CONDITIONS WILL BECOME MORE WIDESPREAD. WILL MAINTAIN MARGINAL LLWS IN THE TAF BETWEEN 06Z-12Z TUESDAY AS A LOW LEVEL JET TRACKS JUST NORTH OF NEW YORK STATE. OUTLOOK... TUESDAY NIGHT...IFR WITH WIDESPREAD RAIN CHANGING TO WET SNOW. WEDNESDAY...MVFR WITH MORNING SNOW SHOWERS IMPROVING TO VFR. THURSDAY...MAINLY VFR. THURSDAY NIGHT AND FRIDAY...MVFR WITH A CHANCE OF RAIN AND SNOW SHOWERS. SATURDAY...VFR. && .MARINE... THE SOUTHERLY FLOW ACROSS THE LOWER LAKES HAS WEAKENED CONSIDERABLY THIS EVENING...BUT WILL PICK UP A LITTLE MORE OVERNIGHT AS A LOW LEVEL JET TRACKS JUST NORTH OF NEW YORK STATE. STILL LOOKS LIKE THE HIGHER WAVES WILL MAINLY IMPACT THE OPEN WATERS OF THE LAKES...AND THE FAR EASTERN NEAR SHORES OF LAKE ONTARIO. A STORM SYSTEM WILL DEVELOP OVER THE MID WEST ON TUESDAY AND APPROACH THE LOWER GREAT LAKES DURING THE AFTERNOON AND EVENING. THIS WILL ACTUALLY WEAKEN THE SFC PRESSURE GRADIENT IN THIS CASE SO THAT WINDS AND WAVES SHOULD BE BELOW SCA CRITERIA. AS THE SYSTEM MOVES TO THE SAINT LAWRENCE VALLEY AND STRENGTHENS TUESDAY NIGHT...STRONG NORTHWEST WINDS WILL DEVELOP ACROSS LAKE ERIE...AND BY DAYBREAK WEDNESDAY...ACROSS LAKE ONTARIO. DEFINITE SCA CONDITIONS WILL BE IN PLACE AT THAT TIME...WITH THE THREAT OF GALE FORCE WINDS. && .BUF WATCHES/WARNINGS/ADVISORIES... NY...NONE. MARINE...SMALL CRAFT ADVISORY UNTIL 4 AM EST TUESDAY FOR LOZ045. && $$ SYNOPSIS...RSH NEAR TERM...RSH/TJP SHORT TERM...APFFEL LONG TERM...APFFEL AVIATION...TJP MARINE...RSH/TJP
AREA FORECAST DISCUSSION
NWS NASHVILLE TN
333 AM CST TUE DEC 27 2011 .DISCUSSION... FORECAST REASONING WILL LEAN TOWARD A CONSENSUS MODEL SOLUTION COMPROMISE FOR THE FORECAST PERIOD UNLESS OTHERWISE NOTED. MAIN FORECAST QUANDARIES...ACTUAL TIMING OF RAINFALL ENDING W TO E AND STRENGTH OF WINDS TODAY...POSSIBLE RAIN/SNOW MIX PLATEAU THIS EVENING...TEMPS...AND OVERALL FORECAST EARLY NEXT WEEK. AS FOR TODAY...AS OF 09Z...WIDE SWATH OF LIGHT TO MODERATE SHWRS MOVING GENERALLY S TO N ACROSS MID STATE ACROSS LOCATIONS GENERALLY ALONG AND E OF I-65. SOME BREAKS IN RAINFALL NOTED W OF THIS AREA... BUT SHWRS DEVELOPING IN VICINITY OF UPPER LEVEL LOW ACROSS W TN AND ERN AK. ALL OF THIS AS SFC LOW CONTINUES TO MOVE ACROSS W TN...WITH UPPER LEVEL TROUGH BEGINNING TO MOVE INTO FAR WRN PORTIONS OF THE STATE. WILL BE MAKING FINAL DECISION AT PRESS TIME...BUT AM LEANING TOWARD DEF SHWRS GENERALLY E OF I-65 TO NUMEROUS SHWRS W...TRANSITIONING TO NUMEROUS TO SCATTERED LIGHT SHWRS ALL LOCATIONS EXPECT THOSE CLOSE TO AND ACROSS THE CUMBERLAND PLATEAU REGION DURING THE LATER MORNING HRS. THIS AFTERNOON THE MID STATE SHOULD EXPERIENCE AREAS ACROSS WRN MIDDLE TN FINALLY BECOME DRY NEAR AND JUST EAST OF THE TN RIVER VALLEY REGION...WITH ISO/SCT LIGHT SHWRS ACROSS THE REMAINDER OF THE MID STATE DURING THE AFTERNOON HRS. THIS REASONING BASED ON THE FACT THAT THE SFC LOW AND UPPER LEVEL TROUGH WILL CONTINUE TO MOVE NEWD OVER TIME WITH CLDY SKIES ACROSS MOST LOCATIONS THRU THE AFTERNOON HRS. HRRR MODEL HINTING AT THE POTENTIAL FOR A RAIN/SNOW MIX ACROSS FAR NW PORTIONS OF THE MID STATE BY THE EARLY AFTERNOON HRS...BUT WITH TEMPS EXPECTED TO REMAIN VERY CLOSE TO CURRENT TEMPS IN THE LOWER 40S THRU THE AFTERNOON HRS...WILL NOT MENTION IN THE SUITE OF FORECAST PRODUCTS AS OF THIS TIME. DO NOT EXPECT OTHER LOCATIONS ACROSS THE MID STATE TO DEVIATE MUCH FROM CURRENT TEMPS BEING EXPERIENCED. AS THIS SYSTEM MOVES NEWD...EXPECT SOME MIXING DOWN OF 30 TO 40 MPH 925MB WINDS TO THE SFC DURING THE AFTERNOON HRS. DO NOT EXPECT ANY LOCATION ACROSS THE MID STATE TO REACH WIND ADVISORY CRITERIA AS OF THIS TIME...BUT WOULD NOT BE SURPRISED THAT SOME LOCATIONS EXPERIENCE GUSTS OF 25 TO 30 MPH LATER THIS AFTERNOON. AS FOR TONIGHT...THERE MIGHT BE A SLIGHT CHANCE OF A RAIN/SNOW MIXTURE ACROSS NRN PORTIONS OF THE CUMBERLAND PLATEAU DURING THE EARLY EVENING HRS AS MOISTURE ASSOCIATED WITH UPPER LEVEL TROUGH MOVES ACROSS THIS PART OF THE MID STATE AND WITH TEMPS EXPECTED TO FALL INTO THE UPPER TO MID 30S. HOWEVER...AS OF THIS TIME...NO ACCUMULATION IS EXPECTED. OTHERWISE...LOOK FOR A SLOW DECREASE IN CLOUDINESS W TO E ACROSS THE MID STATE...WITH DRY CONDITIONS...AND LOWS NEAR NORMAL VALUES FOR THIS TIME OF YEAR...AROUND 30...UPPER 20S PLATEAU. AS FOR WED...A WEAK SHORTWAVE PASSAGE IS EXPECTED ACROSS THE SRN OHIO VALLEY AND PORTIONS OF KY DURING THE AFTERNOON HRS...WHICH MIGHT BRING SOME ADDITIONAL CLOUDINESS TO LOCATIONS APPROACHING THE TN/KY BORDER. HOWEVER...AT THIS TIME...WILL GO WITH PTCDLY SKIES ACROSS THE ENTIRE MID STATE...WITH AFTERNOON HIGH TEMPS GETTING BACK CLOSE TO CLIMATOLOGICAL NORMS...WITH HIGHS IN THE MID 40S N TO UPPER 40S S...LOW 40S PLATEAU. AS FOR WED NIGHT...SKIES SHOULD EVENTUALLY BECOME MOCLR BY LATE WED NIGHT...WITH LOWS AGAIN IN THE LOWER 30S...UPPER 20S PLATEAU. AS FOR THU...AS HIGH SHIFTS EWD...AND MORE OF A SLY SFC FLOW DEVELOPS ACROSS THE MID STATE...HIGHS SHOULD WARM UP INTO THE LOWER TO MID 50S... WITH PTCLDY SKIES AND DRY CONDITIONS. AS FOR THE REST OF THE FORECAST PERIOD...WILL KEEP IT DRY THRU NEW YEARS DAY...WHEN THE NEXT CHANCE OF RAINFALL ACROSS THE MID STATE WILL OCCUR AS ANOTHER COLD FRONT IS EXPECTED TO MOVE ACROSS THE MID STATE. INTO THE FIRST HALF OF NEXT WEEK THOUGH...SIGNIFICANT MODEL DIFFERENCES ARE OCCURRING. THE GFS BEING THE DRIER AND WARMER SOLUTION AND THE EURO BEING THE COLDER AND WETTER SOLUTION. AM GOING TO PLAY IT MIDDLE OF THE ROAD HERE...AND GO WITH A DRY FORECAST...A LEAN MORE TOWARD THE GFS...AS I AM A LITTLE WEARY OF THE VERY PROGRESSIVE AND DEEP UPPER LEVEL LOW AND TROUGH SOLUTION THAT THE EURO IS ADVERTISING ACROSS THE MID SOUTH NEXT TUE INTO WED. THRU THIS PERIOD...AFTERNOON HIGH TEMPS WILL MAINLY BE IN THE 50S...WITH OVERNIGHT LOWS...EXPECT FOR SAT NIGHT WHICH WILL BE IN THE MID 40S...MAINLY IN THE 30S. && .PRELIMINARY POINT TEMPS/POPS... NASHVILLE 44 30 44 31 / 100 10 0 0 CLARKSVILLE 44 28 44 31 / 70 10 0 0 CROSSVILLE 42 28 42 29 / 100 20 0 0 COLUMBIA 45 30 46 31 / 70 10 0 0 LAWRENCEBURG 47 29 48 30 / 70 10 0 0 WAVERLY 44 29 46 32 / 70 10 0 0 && .OHX WATCHES/WARNINGS/ADVISORIES... NONE. && $$ 31
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
305 AM CST TUE DEC 27 2011 .SHORT TERM...TODAY THROUGH THURSDAY NIGHT 305 AM CST TUE DEC 27 2011 MAIN FORECAST CONCERN IS ON LOW PRECIPITATION CHANCES THROUGHOUT THE SHORT TERM PERIOD. CURRENTLY AS OF 08Z...WATER VAPOR LOOP AND RUC 500MB HEIGHT ANALYSIS SHOWED A SHORTWAVE TROUGH OVER BRITISH COLUMBIA...WEAK RIDGING OVER THE SOUTHWEST U.S. INTO ALBERTA AND SASKATCHEWAN...AN UPPER TROUGH OVER MINNESOTA AND AN UPPER LOW OVER NORTHERN MISSISSIPPI. THE UPPER TROUGH IS GRADUALLY BRINGING COLDER AIR INTO THE UPPER MISSISSIPPI RIVER VALLEY REGION...NOTED BY 850MB TEMPS THAT FELL BETWEEN 12Z YESTERDAY AND 00Z TODAY FROM 4C TO 1C AT MPX...AND 6 TO -2C AT BIS. MORE COLD AIR LURKS FARTHER UPSTREAM WITH -12C REPORTED AT THE PAS MANITOBA. MID TO UPPER LEVEL DYNAMIC LIFT WITH THE TROUGH IS FAIRLY WEAK AND MOSTLY OFF TO THE EAST OVER LAKE MICHIGAN...PER QG APPEARANCE FROM THE RUC/ECMWF. THIS LIFT IS WHAT HELPED PRODUCE THE RAIN/SLEET/SNOW LAST EVENING. BIGGER ISSUE WITH THE UPPER TROUGH IS ACTUALLY THE SUBSIDENCE AND THE COLD ADVECTION...WHICH IS HELPING TO PRODUCE 15-20 KT SURFACE SUSTAINED WINDS AND GUSTS TO 30 KT ACROSS MUCH OF MINNESOTA. THESE ARE OCCURRING IN THE WAKE OF TWO COLD FRONTS: THE FIRST SITUATED NORTH-SOUTH OVER CENTRAL WISCONSIN AND THE SECOND ALIGNED WEST EAST FROM ABERDEEN SOUTH DAKOTA INTO UPPER MICHIGAN. A LARGE AMOUNT OF STRATUS EXISTS BEHIND THESE FRONTS...WITH THE LOWEST CEILINGS BEHIND THE SECONDARY FRONT WHERE A GREATER SURGE OF COLD AIR ADVECTION IS HELPING TO UNDERCUT LOW LEVEL MOISTURE. A FEW FLURRIES ALSO OCCURRING FROM THE STRATUS. TODAY AND TONIGHT...MODELS PROG THE UPPER TROUGH OVER MINNESOTA TO MOVE RAPIDLY TO THE EAST...IN RESPONSE TO FAST FLOW COMING OFF THE PACIFIC. BY MIDNIGHT TONIGHT...THE UPSTREAM WEAK RIDGING SHOULD HAVE MOVED INTO THE FORECAST AREA. THIS SITUATION MEANS THAT THE CURRENT STRATUS AND STRONGER WINDS MOVING INTO THE FORECAST AREA FROM MINNESOTA WILL NOT STAY AROUND LONG. IN FACT...GOOD MODEL AGREEMENT EXISTS THAT SKIES SHOULD CLEAR OUT ACROSS MINNESOTA AND IOWA BETWEEN 18-21Z TODAY. ON THE OTHER HAND...OVER WISCONSIN...THERE ARE SUGGESTIONS BY THE 27.00Z NAM/27.03Z RUC THAT THE STRATUS MAY LINGER THROUGH THE EVENING BEFORE DISSIPATING AFTER MIDNIGHT (PER 925MB RH DATA). THIS CERTAINLY SEEMS PLAUSIBLE...SINCE STRATUS TYPICALLY LINGERS LONGER THAN ONE WOULD EXPECT THIS TIME OF YEAR. ALSO...THERE SHOULD BE A GOOD TRANSPORT OF MOISTURE OFF LAKE SUPERIOR GIVEN COLDER AIR FLOWING SOUTH. THEREFORE...HAVE RAISED SKY COVER VALUES OVER WISCONSIN FOR THIS EVENING. REGARDING PRECIP CHANCES WITH THE STRATUS...ANY LIFT IS VERY WEAK...ASSOCIATED WITH LOW LEVEL FRONTOGENESIS. GIVEN OVERALL LACK OF PRECIPITATION RIGHT NOW ON RADAR...ONLY WENT WITH FLURRIES THIS MORNING. DRYING TREND SHOWING UP NOW IN THE HRRR RUNS WOULD AGREE WITH THIS AS WELL. AFTER THAT... SUBSIDENCE TAKING HOLD SHOULD SHUT OFF ANY PRECIPITATION ACTION. LOOKING AHEAD TO AFTER MIDNIGHT TONIGHT...SHORTWAVE TROUGH OVER BRITISH COLUMBIA ALONG WITH A WEAKER SHORTWAVE CURRENTLY SEEN OVER IDAHO ARE FORECAST TO BEGIN TO DROP DOWN INTO MINNESOTA AROUND 12Z TUESDAY. WARM ADVECTION AHEAD OF THESE SHOULD RESULT IN A MID CLOUD DECK OF STRATUS...WHILE ANY PRECIPITATION STAYS NORTHWEST OF THE FORECAST AREA. REGARDING TEMPERATURES...WITH COLD ADVECTION OCCURRING TODAY NOTED BY 850MB TEMPS FALLING TO -5 TO -8C BY 18Z...ANTICIPATING GENERALLY STEADY OR FALLING TEMPERATURES. TONIGHT IS A LITTLE TRICKY WITH STRATUS OVER WISCONSIN AND THEN CLOUDS COMING IN AFTER MIDNIGHT EVERYWHERE. FOR NOW HAVE FOLLOWED A BLEND OF GUIDANCE FOR LOWS. WEDNESDAY AND WEDNESDAY NIGHT...SHORTWAVE OVER MINNESOTA AT 12Z WEDNESDAY IS FORECAST TO SHIFT EAST FAIRLY QUICKLY...REACHING LOWER MICHIGAN BY 00Z THURSDAY. BIGGEST CONCERN WITH THIS SHORTWAVE IS POTENTIAL FOR SOME WARM ADVECTION LIGHT SNOW SKIRTING TAYLOR AND CLARK COUNTIES. THE 00Z NAM/26.21Z SREF SUGGEST THIS IS POSSIBLE... WHEREAS THE 27.00Z GFS/26.12Z ECMWF ARE DRY. GIVEN THE WAY RECENT SYSTEMS HAVE GONE...WITH LIGHT PRECIPITATION HAPPENING DESPITE PRESENCE OF LOW LEVEL DRY AIR...FEEL COMPELLED TO AT LEAST PLACE A 20 PERCENT CHANCE IN TAYLOR AND CLARK COUNTIES. ELSEWHERE...A DECREASING CLOUD TREND SHOULD OCCUR WITH TEMPERATURES CLIMBING INTO THE 30S. COULD SEE READINGS PUSH 40 IN FAR WESTERN AREAS. FOR WEDNESDAY NIGHT...ATTENTION RE-FOCUSES TO THE NORTHWEST WHERE MODELS SHOW A DECENT SHORTWAVE MOVING THROUGH A FAST WEST-NORTHWEST UPPER LEVEL FLOW. AT 00Z...MODELS SUGGEST IT IS EITHER OVER EASTERN MONTANA OR SOUTHEAST SASKATCHEWAN...THEN IT MARCHES SOUTHEAST INTO THE FORECAST AREA AROUND 12Z THURSDAY. AS FAR AS WHERE IN THE FORECAST AREA...THIS VARIES GREATLY...SO FOR NOW HAVE TAKEN A BLEND APPROACH GIVEN THE FAST FLOW. AS THE SHORTWAVE APPROACHES...SHOULD SEE MID AND HIGH CLOUDS DEVELOP IN RESPONSE TO WARM ADVECTION AND DPVA FORCING. LIGHT PRECIPITATION COULD EVEN START BREAKING OUT IN NORTHWESTERN PORTIONS OF THE AREA IN THE EVENING. AFTER MIDNIGHT... ANTICIPATING SOME LIGHT PRECIPITATION EVERYWHERE. PRECIPITATION CHANCES REMAIN IN THE 20 TO 30 RANGE...HOWEVER...DUE TO THE LARGE SPREAD IN TRACK OF THE SHORTWAVE. ENVISION CHANCES NEEDING A BUMP UP IN LATER FORECASTS...BUT WHERE IS THE QUESTION. WITH THE CLOUDS MOVING IN...NOT ANTICIPATING AS MUCH OF A TEMPERATURE FALL AS TONIGHT. GENERALLY FOLLOWED A BLEND OF GUIDANCE FOR LOWS. THURSDAY AND THURSDAY NIGHT...SIMILAR TO THE PAST FEW DAYS...THE PARADE OF SHORTWAVES FROM THE PACIFIC CONTINUE TO COME THROUGH THE FAST FLOW. SHORTWAVE THAT IS NEAR/OVER THE AREA AT 12Z THURSDAY IS PROGGED TO REACH LOWER MICHIGAN BY 00Z...WHILE ANOTHER SHORTWAVE MOVES INTO THE DAKOTAS. SHOULD SEE THE PRECIPITATION DIMINISH FOR A TIME THURSDAY...ESPECIALLY IN THE AFTERNOON NORTH OF I-90 AS THAT AREA GETS INTO THE SUBSIDENCE BEHIND THE MORNING SHORTWAVE. DURING THE AFTERNOON...PRECIPITATION IS POSSIBLE SOUTH OF I-90 AS WARM ADVECTION OCCURS DOWNSTREAM OF THE SHORTWAVE ENTERING THE DAKOTAS. WITH UNCERTAINTY ON THE PLACEMENT OF THE SHORTWAVE NEAR/OVER THE AREA AT 12Z THURSDAY...ALONG WITH SUGGESTIONS OF LOW LEVEL DRY AIR TO OVERCOME IN SOUNDINGS...HAVE KEPT PRECIPITATION CHANCES BETWEEN 20 AND 30. A LOT OF UNCERTAINTY EXISTS WITH THIS DAKOTAS SHORTWAVE HEADING INTO THURSDAY NIGHT...WHERE THE 27.00Z ECMWF/UKMET DROP IT DOWN INTO MISSOURI WHEREAS THE 27.00Z GFS CROSSES IOWA AND THE 27.00Z NAM CROSSES THE FORECAST AREA. FEELING IS THE SOUTHERN SOLUTIONS MAY HAVE A BETTER CHANCE OF VERIFYING...DUE TO THE USUAL BETTER PREDICTABILITY OF THE ECMWF...BUT NOT COMPLETELY SURE GIVEN THE FAST FLOW. THEREFORE...20 TO 30 PERCENT CHANCES CONTINUE FOR THURSDAY NIGHT. WITH SO MUCH UNCERTAINTY ON THE TRACKS OF THESE SHORTWAVES...TEMPERATURE FORECASTS ARE PROBLEMATIC. CERTAINLY POTENTIAL EXISTS ON THURSDAY FOR AT LEAST THE SOUTHERN PORTION OF THE AREA TO HIT 40 OR HIGHER...ESPECIALLY IF THE SHORTWAVE THEN TRACKS FARTHER NORTH. CLOUDS THURSDAY NIGHT SHOULD HOLD TEMPERATURES UP IN THE 20S TO LOW 30S...COLDEST IN TAYLOR AND CLARK COUNTIES WHERE COOLER AIR SINKS SOUTH BEHIND THE SHORTWAVE MOSTLY SUGGESTED TO TRACK NEAR OR SOUTH OF THE AREA. .LONG TERM...FRIDAY THROUGH MONDAY NIGHT 305 AM CST TUE DEC 27 2011 27.00Z MODEL CYCLE CONSISTING OF THE ECMWF/GFS/CANADIAN AND GFS ENSEMBLES STILL PRESENT PLENTY OF UNCERTAINTY WITH REGARDS TO THE UPPER LEVEL PATTERN THROUGHOUT THE LONG TERM PERIOD...THOUGH THERE ARE SOME FEATURES THAT CAN BE LATCHED ONTO. THE FIRST IS A FAIRLY POTENT SHORTWAVE TROUGH POISED TO COME INTO THE PACIFIC NORTHWEST ON FRIDAY...RESULTING IN BUILDING RIDGING DOWNSTREAM TOWARDS THE FORECAST AREA. THIS RIDGING LOOKS TO BUILD INTO THE AREA FRIDAY NIGHT...BRINGING IN A SURGE OF DOWNSLOPED PACIFIC AIR. TIMING THE PACIFIC NORTHWEST SHORTWAVE TROUGH AND INTENSITY WILL BE CRITICAL IN DETERMINING HOW WARM NEW YEARS EVE IS. LOOKS LIKE THERE SHOULD BE SOME WARM ADVECTION PRECIPITATION DOWNSTREAM INTO THE AREA FRIDAY/FRIDAY NIGHT...BUT THIS MOSTLY LIFTS NORTH ON NEW YEARS EVE. THE 26.12Z/27.00Z ECMWF RUNS ARE BY FAR THE MOST AMPLIFIED... RESULTING IN A SLOWER COLD FRONTAL PASSAGE AND HIGH TEMPERATURES SATURDAY FROM THE 40S INTO THE LOW 50S. FOR NOW HAVE TAKEN A 30 DAY BIAS CORRECTION OF THE CONSENSUS OF ALL GUIDANCE...WHICH RESULTS IN HIGHS MOSTLY IN THE 40S. CERTAINLY POTENTIAL EXISTS FOR WARMER READINGS GIVEN LACK OF SNOW COVER STILL ANTICIPATED. COLDER AIR WILL MOVE INTO THE AREA FOR NEW YEARS DAY AS THE UPPER TROUGH MOVES IN...BUT HOW MUCH DEPENDS ON THE PROGRESSIVE NATURE OF THE UPPER TROUGH. THE MORE AMPLIFIED ECMWF BASICALLY TURNS THE TROUGH INTO A LONGWAVE TROUGH...ALLOWING FOR AIR OF MORE ARCTIC ORIGIN TO FLOW SOUTH INTO THE AREA FOR NEW YEARS DAY AND MONDAY. ON THE OTHER HAND...THE 27.00Z GFS/CANADIAN DEPICT MUCH MORE PROGRESSION... RESULTING IN A CONTINUED FEED OF PACIFIC AIR AND WARMER. GIVEN SO MUCH UNCERTAINTY...A CONSENSUS OF GUIDANCE WAS FOLLOWED FOR NEW YEARS DAY THROUGH MONDAY NIGHT. IN EITHER MODEL CAMP SCENARIO...IT LOOKS LIKE LITTLE IF ANY PRECIPITATION WILL OCCUR. && .AVIATION...THROUGH 06Z WEDNESDAY 1109 PM CST MON DEC 26 2011 COUPLE OF CONCERNS FOR THE AVIATION FORECAST...MOSTLY RELATING TO A COLD FRONTAL PASSAGE THROUGH THE TAF SITES EXPECTED BETWEEN 08-09Z. PRIOR TO THE FRONTAL PASSAGE...PLAN ON VFR CONDITIONS TO CONTINUE WITH SOUTH TO SOUTHWEST WINDS HOVERING BETWEEN 5 AND 15 KT...HIGHEST AT KRST. THESE WINDS WILL INCREASE BEHIND THE COLD FRONT WHILE VEERING TO THE NORTHWEST. ANTICIPATING SUSTAINED WINDS OF 15 TO 20 KT AND GUSTS OF 25 TO 30 KT...HIGHEST AT KRST. ALSO...AN AREA OF MVFR STRATUS AND SOME SPRINKLES/FLURRIES/VERY LIGHT SNOW SHOWERS WILL COME IN BEHIND THE COLD FRONT. PLAN ON THE MVFR STRATUS AND BLUSTERY WINDS TO PERSIST THROUGH THE MORNING. DURING THE AFTERNOON...PARTICULARLY AROUND 20-21Z...HIGH PRESSURE BUILDING IN FROM THE WEST SHOULD HELP DIMINISH THE WINDS. DRY AIR ASSOCIATED WITH THE RIDGE WILL ALSO CLEAR THE STRATUS OUT AT KRST. HOWEVER...THE STRATUS MAY WANT TO LINGER AT KLSE THROUGH THE EVENING WITH A NORTH FLOW BRINGING MOISTURE FROM LAKE SUPERIOR. THEREFORE...HAVE DELAYED ANY CLEARING AT KLSE UNTIL 02Z AT THE EARLIEST. EVEN THEN...THIS MAY NEED TO BE DELAYED IN FUTURE TAF FORECASTS. && .ARX WATCHES/WARNINGS/ADVISORIES... 305 AM CST TUE DEC 27 2011 WI...NONE. MN...NONE. IA...NONE. && $$ SHORT TERM...AJ LONG TERM...AJ AVIATION...AJ
AREA FORECAST DISCUSSION
NWS MILWAUKEE/SULLIVAN WI
1116 PM CST MON DEC 26 2011 .UPDATE... VERY LGT RAIN OR SPRINKLES WILL END SHORTLY AFTER MIDNIGHT OVER FAR SE WI. OTHERWISE THE COLD FRONT WILL ARRIVE OVER SOUTH CENTRAL WI AROUND SUNRISE AND BY 14Z OVER FAR ERN WI. STRATUS CLOUDS AND POSSIBLY FLURRIES WILL THEN PREVAIL IN THE COLD ADVECTION AND CYCLONIC FLOW AFTER THE COLD FRONT. && AVIATION/06Z TAFS/... VFR CONDITIONS TO PREVAIL UNTIL STRATUS WITH MVFR CIGS ARRIVES WITH THE COLD FRONT JUST AFTER SUNRISE TUE MORNING. A FEW FLURRIES MAY OCCUR IN THE CYCLONIC FLOW BUT STRATUS CLOUDS SHOULD BECOME SCT BY LATE AFTERNOON AND EVENING WITH CONTINUED COLD AND DRY ADVECTION. && .PREV DISCUSSION... /ISSUED 142 PM CST MON DEC 26 2011/ SHORT TERM... TONIGHT AND TUESDAY - CONFIDENCE...MEDIUM WATER VAPOR/RUC COMBO SHOWS SOUTHERN STREAM ENERGY CRUISING THROUGH NRN TX WITH NORTHERN STREAM WAVE TRAVERSING EAST FROM ND INTO NRN MN. SOME INCREASE IN MOISTURE NOTED OUT AHEAD OF SOUTHERN WAVE. MID/HIGH CLOUDS RACING NORTHEAST FROM ERN IA AND CENTRAL IL WILL OVERSPREAD SRN WI THIS EVENING. LOW LEVELS WILL BE SLOW TO SATURATE PER RUC AND NAM BUFKIT SOUNDINGS. IN FACT...THE LOW LEVELS REALLY DO NOT MOISTEN UP UNTIL THE COLD AIR ADVECTION REGIME KICKS IN ON TUESDAY. QPF TIED MORE TO RIGHT REAR QUADRANT AND THIS KEEPS PRECIP JUST TO OUR SE. MODELS GENERATE LIGHT QPF TUESDAY IN COLD AIR ADVECTION REGIME...WITH NORTHERN STREAM MID LEVEL TROUGH PASSAGE. WILL GO WITH THE LOW POP/SHSN IDEA WITH MORE OF A FLURRY SCENARIO IN THE AFTERNOON. OVERALL DEPTH OF MOISTURE LOOKS UNIMPRESSIVE. LOW LEVELS A BIT MORE MOIST IN THE CAA REGIME. TEMPS WILL BE NOTICEABLY COOLER WITH THE CLOUD COVER/GUSTY NW WINDS AND 925 TEMPS DROPPING TO -6 TO -8C. TUESDAY NIGHT AND WEDNESDAY...FORECAST CONFIDENCE...MEDIUM. AS THE STRONG SHORTWAVE MOVES OFF...A MORE WEST/NORTHWEST FAST FLOW IS EXPECTED IN THE MID/UPPER LEVELS. ONE WEAK SHORTWAVE MOVES ACROSS SOUTHERN WISCONSIN WEDNESDAY MORNING WHILE A SECOND STRONGER SHORTWAVE APPROACHES LAKE SUPERIOR AREA LATE WEDNESDAY AFTERNOON. THE PRECIPITATION FROM THIS SHORTWAVE IS EXPECTED TO REMAIN TO THE NORTH. A SURFACE HIGH WILL CROSS WISCONSIN TUESDAY NIGHT BEFORE WARM AIR ADVECTION TAKES HOLD ON WEDNESDAY. LOW LEVELS ARE DRY WITH ONLY MID LEVELS SATURATING ON WEDNESDAY WITH THE APPROACHING SHORTWAVE. WEDNESDAY NIGHT AND THURSDAY...FORECAST CONFIDENCE...MEDIUM. THE SHORTWAVE MOVES ACROSS THE UPPER GREAT LAKES WEDNESDAY NIGHT AS A BROAD ZONAL FLOW DEVELOPS IN THE MID/UPPER LEVELS AS A RATHER WEAK SHORTWAVE MOVES TOWARDS NORTHERN MINNESOTA. ASSOCIATED WEAK SURFACE LOW SHOULD REACH NORTHWEST MINNESOTA THURSDAY AFTERNOON WITH SOUTH FLOW DEVELOPING ACROSS SOUTHERN WISCONSIN. LONG TERM... FRIDAY THROUGH SUNDAY...FORECAST CONFIDENCE MEDIUM. THE MILD WEATHER PATTERN CONTINUES AS THE MODELS CONTINUE THE PARADE OF WEAK SHORTWAVES IN THE FAST ZONAL FLOW. ONE SHORTWAVE MOVES ACROSS FRIDAY. 12Z GFS TAKES A FAST SHORTWAVE JUST NORTH OF LAKE SUPERIOR WHILE THE 00Z ECMWF BEGINS TO DIG A MAJOR TROUGH OVER THE PLAINS. FOR NOW WILL LEAN MORE TOWARD THE GFS. A WEAK TROUGH OF LOW PRESSURE MOVES ACROSS WISCONSIN FRIDAY WHILE WITH A WEAK RIDGE ON THE 12Z GFS. MOTH MODELS DEVELOP A TROUGH OVER THE WESTERN GREAT LAKES SUNDAY...BUT GFS IS FARTHER NORTH WITH THE 00Z ECMWF EXTENDING THE TROUGH INTO SOUTHEAST MISSOURI AND STRENGTHENS IT. NOT READY TO BUY IN TO THIS SCENARIO AND WILL TREND TOWARD THE 12Z GFS. NEW 12Z ECMWF HAS NOW TRENDED TOWARD THE 12Z GFS. MONDAY...FORECAST CONFIDENCE MEDIUM. AS THE UPPER TROUGH DEEPENS ON THE 00Z ECMWF IT TAKES A STRONG SURFACE LOW NORTH INTO LOWER MICHIGAN. MEANWHILE THE GFS QUICKLY PUSHES A SURFACE LOW OFF THE SOUTHEAST CANADIAN COAST WITH HIGH PRESSURE BUILDING OVER THE UPPER MIDWEST. THE GFS IS MORE CONSISTENT WITH THE 06Z DGEX AND WILL TREND MORE TOWARD THESE MODELS. NEW 12Z ECMWF HAS NOW TRENDED MORE TOWARD THE 12Z GFS BUT THE 12Z ECMWF STILLS DIGS THE MID/UPPER TROUGH MORE ACROSS THE EASTERN GREAT LAKES. PREFER THE LOWER AMPLITUDE 12Z GFS/06Z DGEX. AVIATION/00Z TAFS/... MID DECK INCREASES THIS EVENING AS SOUTHWEST FLOW BRINGS MOISTURE UP AND OUT AHEAD OF SOUTHERN STREAM UPPER LOW. LOWER LEVELS NOT PROGGED TO SATURATE UNTIL COLD AIR ADVECTION REGIME KICKS IN ON TUESDAY. WILL GO WITH MVFR CEILINGS. SPOTTY LIGHT PRECIP IS POSSIBLE THOUGH NOT EXPECTING ANYTHING MAJOR WITH COLUMN MOISTURE LOOKING MEAGER. MARINE... STRONG SOUTHWEST GRADIENT BETWEEN LOW CROSSING SOUTHERN CANADA AND HIGH IN EASTERN US. WINDS HAVE RAMPED UP AND GUSTING TO SCA CRITERIA. WINDS MAY DROP BRIEFLY BELOW ADVISORY CRITERIA LATE TONIGHT AND EARLY TUESDAY BEFORE STRONG PRESSURE RISES AND COLD ADVECTION BEHIND COLD FRONT KICK IN AND KEEP THINGS BRISK INTO TUESDAY EVENING. SMALL CRAFT ADVISORY RUNS FROM TODAY THROUGH EARLY WEDNESDAY FOR SIMPLICITY. && .MKX WATCHES/WARNINGS/ADVISORIES... WI...NONE. LM...SMALL CRAFT ADVISORY UNTIL 9 AM CST WEDNESDAY FOR LMZ643>646. && $$ UPDATE...GEHRING TONIGHT/TUESDAY AND AVIATION/MARINE...COLLAR TUESDAY NIGHT THROUGH MONDAY...HENTZ
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
1109 PM CST MON DEC 26 2011 .SHORT TERM...TONIGHT THROUGH THURSDAY 535 PM CST MON DEC 26 2011 535 PM...QUICK UPDATE. BOTH MID CLOUD AND PRECIPITATION COVERAGE A LITTLE MORE THAN PREVIOUSLY FORECAST. HAVE UPDATED THE FORECAST FOR THIS EVENING TO ACCOUNT FOR CLOUDIER SKIES THIS EVENING...AS WELL AS TO INCLUDE ISOLATED/SCATTERED RAIN SHOWERS OVER NORTHEAST IOWA AND SOUTHWEST WISCONSIN. IN ADDITION...WITH TEMPERATURES ALREADY FALLEN TO 37 AT DECORAH...HAVE PUT IN A MIX OF SNOW/SLEET WITH THE RAIN. A COOP OBSERVER IN STANLEY IOWA REPORTED A MIX OF RAIN/SLEET/SNOW IN STANLEY...WHICH CHANGED OVER TO ALL RAIN WHEN DRIVING UP TO OELWEIN. LOOKS LIKE THE BULK OF THE PRECIPITATION SHOULD BE EAST OF THE AREA AROUND 03Z. PREVIOUS FORECAST ISSUED AT 249 PM... THE MAIN FOCUS IN THE SHORT TERM IS ON THE PRECIPITATION CHANCES TONIGHT INTO TOMORROW...FOLLOWED BY ANOTHER SYSTEM WEDNESDAY NIGHT INTO THURSDAY. GUSTY SOUTHWEST WINDS DEVELOPED TODAY AHEAD OF A COLD FRONT THAT CURRENTLY EXTENDS SOUTH OF A SURFACE LOW IN FAR SOUTHWEST ONTARIO DOWN THROUGH EASTERN MINNESOTA AND WESTERN IOWA TOWARD OMAHA. WITH INCREASING CLOUD COVER AND A WEAKENING PRESSURE GRADIENT...WILL BE ALLOWING THE WIND ADVISORY TO EXPIRE AT 3PM THIS AFTERNOON. FURTHER ALOFT...A CUT OFF LOW OVER THE SOUTHERN PLAINS WAS STARTING TO GET A KICK EASTWARD FROM A NORTHERN STREAM TROUGH PROPAGATING EAST THROUGH SOUTHERN CANADA. A FEW SHOWERS HAVE KICKED UP DOWN SOUTH CLOSER TO THE CUT OFF LOW AND SOME OF THE HI- RES MESO MODELS DO CONTINUE TO SHOW SOME RETURNS GOING INTO THE EVENING AHEAD OF THE COLD FRONT...MAINLY IN NORTHEAST IOWA AND SOUTHWEST WISCONSIN. 26.18Z RUC SOUNDINGS OUT OF DBQ/BLR/MSN SHOW A QUICK MOISTENING UP OF THE LOW LEVELS THIS EVENING TOWARD 23-03Z BEFORE THE FRONT COMES THROUGH. THESE THERMAL PROFILES SHOW A WARM LAYER OF 4C AROUND 925MB AND SURFACE TEMPERATURES ABOVE FREEZING...SO ANY PRECIPITATION THAT FALLS TONIGHT AHEAD OF THE FRONT SHOULD STAY IN LIQUID FORM AND NOT REFREEZE. AFTER THIS FIRST COLD FRONT COMES THROUGH...A SECONDARY COLD FRONT WILL SWING AROUND ON THE BACK SIDE OF THE SURFACE LOW AND COME THROUGH THE REGION LATE TONIGHT INTO TOMORROW MORNING. 26.12Z NAM/GFS AND 26.18Z RUC SOUNDINGS SHOW STEEPENING LOW LEVEL LAPSE RATES WITH AN INCREASE IN MOISTURE RIGHT AROUND THE INVERSION. WITH TEMPERATURES IN 925-875MB DROPPING INTO THE -8 TO -10C RANGE...IT SHOULD BE COLD ENOUGH FOR ICE TO FORM. THERE IS NOT MUCH FORCING TO WORK WITH...BUT THE COMBINATION OF STEEP LAPSE RATES...MOISTURE AND ICE AVAILABLE...SHOULD SEE SOME LIGHT SNOW OR FLURRIES WITH A DUSTING OF SNOW ACCUMULATION NOT OUT OF THE QUESTION IN SPOTS. THE 26.12Z GFS APPEARS TO BE AN OUTLIER AT THIS POINT WITH SHOWING MUCH DEEPER MOISTURE ACROSS ALL OF THE REGION AND TRIES TO PUT DOWN A MUCH LARGER AREA OF ACCUMULATING LIGHT SNOW THROUGH TOMORROW MORNING. WITH THE LOW LEVEL MIXING AND A TIGHT PRESSURE GRADIENT IN PLACE...IT WILL BE ANOTHER WINDY DAY TOMORROW WITH WIND GUSTS UP TO 30KTS IN THE HIGHER TERRAIN. A RIDGE OF HIGH PRESSURE WILL MOVE THROUGH TOMORROW NIGHT INTO EARLY WEDNESDAY BEFORE ANOTHER QUICK MOVING MID LEVEL TROUGH PROPAGATES EAST ACROSS SOUTHERN CANADA THROUGH THE MAINLY ZONAL FLOW. THE BETTER FORCING GOES NORTH TOWARD LAKE SUPERIOR WITH THE LOW ON WEDNESDAY BUT ANOTHER QUICK MOVING TROUGH WILL UNDERCUT THIS LOW AND BRING SOME BETTER CHANCES FOR PRECIPITATION WEDNESDAY NIGHT INTO THURSDAY. PRECIPITATION TYPE WILL BE AN ISSUE WITH THE THERMAL PROFILE LIKELY WARMING ENOUGH FOR IT TO POSSIBLY CHANGE OVER TO RAIN...ESPECIALLY ALONG AND SOUTH OF THE I-94 CORRIDOR. .LONG TERM...THURSDAY NIGHT THROUGH MONDAY 249 PM CST MON DEC 26 2011 CONFIDENCE IN THE LONG TERM REMAINS LOW GIVEN THE FAST ZONAL FLOW AND THE DIFFERENCES THAT HAVE BEEN SHOWING UP BETWEEN THE GEM/GFS/ECMWF. RUN TO RUN CONSISTENCY IN THE MODELS HAS NOT BEEN VERY GOOD IN THE EXTENDED...SO HAVE TRIED TO HIGHLIGHT THE BEST CHANCES FOR ANY OVERLAP BETWEEN THESE MODELS...WHICH IS MAINLY THURSDAY NIGHT INTO FRIDAY. AFTER THIS SERIES OF SHORTWAVE TROUGHS COME THROUGH...IT LOOKS LIKE THERE WILL BE A PERIOD OF RIDGING GOING INTO THE WEEKEND. AFTER THIS RIDGE SHIFTS EAST BY SATURDAY NIGHT...THE FOCUS IS ON ANOTHER TROUGH AND HOW DEEP IT DIGS SOUTH. THE 26.12Z GFS KEEPS MORE OF A ZONAL FLOW AND OPEN WAVE WHILE THE 26.12Z ECMWF AND GEM START CARVING OUT A MUCH MORE AMPLIFIED WAVE. THE IMPACT PRECIPITATION WISE FOR OUR AREA IS NOT MUCH AS IT APPEARS THAT THE FOCUS WOULD BE OFF TO THE EAST. && .AVIATION...THROUGH 06Z WEDNESDAY 1109 PM CST MON DEC 26 2011 COUPLE OF CONCERNS FOR THE AVIATION FORECAST...MOSTLY RELATING TO A COLD FRONTAL PASSAGE THROUGH THE TAF SITES EXPECTED BETWEEN 08-09Z. PRIOR TO THE FRONTAL PASSAGE...PLAN ON VFR CONDITIONS TO CONTINUE WITH SOUTH TO SOUTHWEST WINDS HOVERING BETWEEN 5 AND 15 KT...HIGHEST AT KRST. THESE WINDS WILL INCREASE BEHIND THE COLD FRONT WHILE VEERING TO THE NORTHWEST. ANTICIPATING SUSTAINED WINDS OF 15 TO 20 KT AND GUSTS OF 25 TO 30 KT...HIGHEST AT KRST. ALSO...AN AREA OF MVFR STRATUS AND SOME SPRINKLES/FLURRIES/VERY LIGHT SNOW SHOWERS WILL COME IN BEHIND THE COLD FRONT. PLAN ON THE MVFR STRATUS AND BLUSTERY WINDS TO PERSIST THROUGH THE MORNING. DURING THE AFTERNOON...PARTICULARLY AROUND 20-21Z...HIGH PRESSURE BUILDING IN FROM THE WEST SHOULD HELP DIMINISH THE WINDS. DRY AIR ASSOCIATED WITH THE RIDGE WILL ALSO CLEAR THE STRATUS OUT AT KRST. HOWEVER...THE STRATUS MAY WANT TO LINGER AT KLSE THROUGH THE EVENING WITH A NORTH FLOW BRINGING MOISTURE FROM LAKE SUPERIOR. THEREFORE...HAVE DELAYED ANY CLEARING AT KLSE UNTIL 02Z AT THE EARLIEST. EVEN THEN...THIS MAY NEED TO BE DELAYED IN FUTURE TAF FORECASTS. && .ARX WATCHES/WARNINGS/ADVISORIES... 249 PM CST MON DEC 26 2011 WI...NONE. MN...NONE. IA...NONE. && $$ SHORT TERM...HALBACH/AJ LONG TERM...HALBACH AVIATION...AJ
AREA FORECAST DISCUSSION
NWS ALBANY NY
1014 AM EST TUE DEC 27 2011 .SYNOPSIS... AN AREA OF LOW PRESSURE WILL TRACK NORTHEAST ACROSS OUR REGION LATE TODAY AND TONIGHT WITH WIDESPREAD PRECIPITATION AND BREEZY CONDITIONS. MAINLY RAIN IS EXPECTED FROM THIS SYSTEM...BUT AREAS WELL NORTH AND WEST OF ALBANY WILL GET SOME LIGHT SNOW ACCUMULATIONS...ESPECIALLY TONIGHT...AS RAIN CHANGES TO SNOW. VERY WINDY AND COLDER CONDITIONS WITH SCATTERED TO NUMEROUS SNOW AND OR RAIN SHOWERS WILL OCCUR WEDNESDAY...AS THE STORM MOVES INTO EASTERN CANADA. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... AS OF 950 AM EDT...LOW PRESSURE CONTINUES TO RAPIDLY FORM NEAR THE SRN APPALACHIANS THIS HOUR. THE BEST MSAS PRESSURE FALLS ARE NEAR W-CNTRL NC. THE WATER VAPOR LOOP HAS A SHORT-WAVE ROTATING AROUND A STRONG SOUTHERN STREAM NEGATIVELY TILTED UPPER TROUGH. A NORTHERN STREAM DISTURBANCE IS ALSO TRYING TO PHASE IN. A DUAL UPPER LEVEL JET STREAK STRUCTURE IS IN PLACE WITH THE STORM DEEPENING AND INTENSIFYING ALONG THE LEFT FROM QUADRANT OF A H250 JET STREAK OF 100+ KTS...AND A 140+ KT JET STREAM IS MOVING ACROSS SRN QUEBEC. THE LOW LEVEL JET WILL INCREASE AHEAD OF THE WAVE. THE H850 WINDS INCREASE TO 45-60 KTS BTWN 18Z-00Z. WE INCREASED THE S/SE WINDS TO 10 TO 20 MPH WITH SOME GUSTS IN THE 30-40 MPH LATE THIS PM AND EARLY THIS EVENING. THE STRONGEST WINDS LOOK LIKE THESE WILL BE ALONG THE SRN GREENS...ERN CATSKILLS...AND PORTIONS OF THE MOHAWK VALLEY INTO THE SRN DACKS. WE SLIGHTLY RETOOLED THE POPS BASED ON THE LATEST HRRR AND NAM12 WITH AN ONSET IN THE 21Z- 00Z TIME FRAME. THIS WAVE IS A FAST MOVER. THE DRY SLOT MAY REACH THE FCST AREA AS EARLY AS 03Z ! THE NAM SHOWS SOME ELEVATED INSTABILITY GRAZING THE SOUTHEAST EXTREME OF THE FCST AREA WITH SHOWALTER VALUES OF 0 TO -1C. THERE MAYBE A RUMBLE OF THUNDER SOUTH AND EAST OF THE CAPITAL REGION EARLY THIS EVENING. WE DID NOT ADD THUNDER TO THE GRIDS YET DUE TO LOW CONFIDENCE AND A SMALL PROBABILITY. FINALLY...A LOOK AT THE CRITICAL THICKNESSES AND MODEL SOUNDINGS INDICATE MAINLY A RAIN PTYPE WITH SOME SNOW TRANSITIONING TO RAIN...THEN BACK TO SNOW OVER THE SRN AND WRN ADIRONDACKS. THERE IS A VERY SMALL CHC OF A BRIEF PERIOD OF SOME POCKETS OF -FZRA IN THE SRN DACKS...BUT WE WERE NOT CONFIDENT TO ADD THIS PTYPE AT THIS TIME. TOTAL SNOWFALL AMOUNTS IN THE SRN DACKS WILL BE IN THE 2 TO 5 INCH RANGE. T/TD/RH/APPARENT TEMPS WERE REDONE BASED ON OBSERVATIONS...AND CLOUDS WERE RETOOLED BASED ON THE VIS/IR PICTURE...AS MID AND HIGH CLOUDS CONTINUES TO THICKEN AND LOWER. PREVIOUS NEAR TERM... AS OF 600 AM...HAVE MADE SOME ADJUSTMENTS TO THE HOURLY TEMP GRIDS...WITH LITTLE ELSE CHANGED. 06Z NAM/GFS ARE NOW IN...AND THEY CONTINUE TO SHOW A STORM TRACK THAT IS OVER THE NORTHWEST PART OF THE FORECAST AREA...SO WARM MOSTLY RAIN SOLUTION USED EARLIER TO PRODUCE THE FORECAST STILL LOOKS GOOD. ****PREVIOUS DISCUSSION**** HAVE WORKED THE PAST FEW NIGHTS AND HAVE SEEN THE MODELS CONTINUE THEIR TREND OF TRACKING THE UPCOMING STORM FURTHER AND FURTHER TO THE WEST. THE CURRENT 00Z RUNS ARE ALL NOW FORECASTING THE LOW TO PASS TO THE NORTH AND WEST OF ALBANY. WITH NO RETREATING FRIGID ARCTIC AIR MASS IN PLACE OVER THE REGION...THE WARMING THAT WILL RESULT FROM SUCH A TRACK WILL PRODUCE MOSTLY RAIN ACROSS THE FORECAST AREA...EVEN THE ADIRONDACK PART OF THE FORECAST AREA. RAIN WILL BEGIN TO SPREAD INTO THE FORECAST AREA FROM THE SOUTHWEST BY AROUND 200 PM...AND SPREAD SO RAPIDLY NORTHEAST THAT BY 5 OR 6 PM WIDESPREAD RAINFALL WILL BE FALLING ACROSS THE ENTIRE FORECAST AREA. A MIX OF SNOW AND RAIN IS POSSIBLE OVER THE FAR NORTHWEST PART OF THE FORECAST AREA...WHICH MAY CONTINUE THROUGH THE EVENING AS A MIX...THEN CHANGE TO ALL SNOW THERE AROUND OF AFTER 06Z TONIGHT. BY THE TIME THE CHANGEOVER TO ALL SNOW BEGINS...THE BULK OF THE PCPN WILL HAVE ALREADY PASSED...SO AM EXPECTING NO MORE THAN 1 TO 4 INCHES OF SNOW ACROSS HERKIMER... HAMILTON...NORTHERN FULTON AND NORTHERN WARREN COUNTIES. ELSEWHERE...RAIN MAY CHANGE TO SNOW BEFORE PCPN ENDS AS WELL...BUT IT WILL OCCUR SO LATE THAT LITTLE IF ANY ACCUMULATION IS EXPECTED. AN INCH OR LESS HAS BEEN FORECAST IN THE CENTRAL MOHAWK VALLEY...THE SCHOHARIE VALLEY AND EASTERN CATSKILLS LATE TONIGHT...WITH LITTLE OR NO SNOW ELSEWHERE. NO WINTER WEATHER ADVISORIES HAVE BEEN ISSUED AT THIS TIME SINCE SNOWFALL AMOUNTS ARE LESS THAN THE ADVISORY CRITERIA. HOWEVER...SINCE WE HAVE BEEN HIGHLIGHTING THIS EVENT IN THE HWOALY PRODUCT FOR THE PAST FEW DAYS...CONTINUED TO MENTION THE SNOW ACCUMULATIONS IN THE LATEST HWOALY. MODEL WIND FORECASTS AT 925 MB AND 850 INDICATE SOUTHERLY WINDS AT THOSE LEVELS WILL INCREASE TO 40 TO 50 KTS LATE TODAY AND THIS EVENING. HOWEVER...MOS WIND FORECASTS AND MODEL SOUNDINGS INDICATE THAT THESE STRONG WINDS ARE NOT LIKELY TO TRANSLATE DOWN TO THE SURFACE DUE TO THE RAIN/PCPN INDUCED LOW LEVEL INVERSION THAT IS LIKELY TO DEVELOP AFTER THE PCPN BEGINS. DAY SHIFT WILL NEED TO MONITOR FOR THE POSSIBILITY THAT THE STRONG SOUTHERLY WINDS ALOFT MAY MIX DOWN TO THE SURFACE...ESPECIALLY IF ANY CONVECTIVE ELEMENTS BEGIN TO DEVELOP LATER TODAY AS THE PCPN APPROACHES. TEMPS TODAY WILL RISE INTO THE UPPER 30S AND 40S BY LATE IN THE DAY...AND GENERALLY REMAIN AT THOSE LEVELS UNTIL THE SURFACE LOW MOVES BY AND WESTERLY WINDS BRING COLDER AIR IN. THIS IS NOT LIKELY TO HAPPEN UNTIL AROUND OR AFTER 06Z TONIGHT. BY SUNRISE WEDNESDAY MORNING...TEMPS WILL EVENTUALLY DROP INTO THE 20S OVER THE NORTHWEST...AND 30S ELSEWHERE. && .SHORT TERM /6 PM THIS EVENING THROUGH THURSDAY/... TYPICAL BLUSTERY CONDITIONS WITH SCATTERED TO NUMEROUS SNOW SHOWERS ACROSS THE REGION ON WEDNESDAY IN THE WAKE OF THE STORM...ESPECIALLY OVER HIGHER TERRAIN AND DOWNWIND OF LAKE ONTARIO. ANOTHER INCH OR TWO OF SNOW IS POSSIBLE FROM THE ADIRONDACKS TO THE MOHAWK AND SCHOHARIE VALLEYS AND EASTERN CATSKILLS ON WEDNESDAY...WITH LESSER AMOUNTS ELSEWHERE. MODELS CONTINUE TO SHOW 925 AND 850 WINDS IN THE 40 TO 50 KT RANGE ON WEDNESDAY...BUT WITH THE MIXING OF THE NOW WEST TO NORTHWEST WINDS DOWN TO THE SURFACE MUCH MORE LIKELY...THERE IS A BETTER CHANCE THAT A WIND ADVISORY MAY BE NEEDED ON WEDNESDAY...AND IT HAS BEEN HIGHLIGHTED IN THE HWOALY PRODUCT ACROSS THE ENTIRE FORECAST AREA. HAVE CURRENTLY FORECAST WINDS OF 15 TO 30 MPH WITH GUSTS OF 35 TO 45 MPH. TEMPS WEDNESDAY MAY ACTUALLY FALL OR REMAIN STEADY AS COLDER AIR SURGES IN. HAVE INDICATED HIGHS ON WEDNESDAY ONLY ABOUT A DEGREE OR TWO HIGHER THAN THE LOWS WEDNESDAY MORNING. WINDS AND SNOW SHOWERS WILL DIMINISH WEDNESDAY EVENING. EXPECT LEFTOVER SNOW SHOWERS TO COMPLETELY END DURING THE EVENING...BUT A DECENT WIND WILL CONTINUE THROUGH THE NIGHT WITH WIND GUSTS OF 25 TO 30 MPH POSSIBLE THROUGH WELL AFTER MIDNIGHT. LOWS WEDNESDAY NIGHT WILL RANGE FROM A FEW DEGREES BELOW ZERO OVER THE ADIRONDACKS...TO THE UPPER TEENS OVER THE SOUTH. A CLIPPER LIKE SYSTEM WILL MOVE THROUGH THE GREAT LAKES ON THURSDAY...BUT IT IS NOT LIKELY TO ARRIVE IN OUR AREA UNTIL THURSDAY NIGHT. SO HAVE KEPT THE FORECAST FOR THURSDAY DRY...BUT DID INCREASE THE CLOUD COVER. HIGHS THURSDAY WILL BE IN THE 20S TO MID 30S. && .LONG TERM /THURSDAY NIGHT THROUGH MONDAY/... A CLIPPER TYPE LOW APPROACHES THE REGION THURSDAY NIGHT RESULTING IN CLOUDY SKIES...LOW CHANCE POPS...AND LOW TEMPS FROM AROUND 10 ABOVE NORTH TO THE UPPER 20S SOUTH. PRECIP AMOUNTS...ALL SNOW... WILL BE VERY LIGHT AS THE THE SYSTEM IS MOISTURE STARVED. THE CLIPPER MOVES ACROSS THE REGION ON FRIDAY. THE GFS IS MORE PROGRESSIVE THAN THE ECMWF WHICH SLOWS DOWN THE MOVEMENT OF THE CLIPPER AND MOVES IT FARTHER SOUTH. WARMER AIR IS DRAWN IN AHEAD OF THE CLIPPER WHICH CHANGES THE PRECIP FROM SNOW TO RAIN OVER MUCH OF THE REGION AND INCREASES THE PRECIP AMOUNTS TO THE SOUTH OF THE RAIN SNOW LINE. HIGHS FRIDAY WILL RANGE FROM AROUND 30 NORTH TO THE LOW 40S SOUTH. THE PASSAGE OF THE CLIPPER WILL BE FOLLOWED BY A SURGE OF COLD AIR WITH 850 TEMPS AROUND MINUS 10 WITH LOWS FRIDAY NIGHT FROM THE HIGH SINGLES NORTH TO THE MID 20S SOUTH. WESTERLY WINDS WILL RESULT IN A CHANCE FOR SOME LAKE ENHANCED PRECIP WITH THE COLD ADVECTION WEST...ENOUGH FOR CHANCE POPS DOWN THE MOHAWK VALLEY AND ELEVATED TERRAIN WEST OF THE HUDSON VALLEY...WITH ONLY SLIGHT CHANCE POPS FARTHER EAST. HIGHS SATURDAY WILL RANGE FROM THE MID 20S TO AROUND 40. HIGH PRESSURE BRIEFLY CROSSES THE REGION SATURDAY INTO SATURDAY NIGHT AND WINDS BACK AROUND TO A SOUTHWESTERLY DIRECTION BRINGING WARMER AIR INTO THE REGION. LOWS SATURDAY NIGHT WILL RANGE FROM AROUND 20 NORTH TO 30 SOUTH. THE NEXT IN A SERIES OF CLIPPERS MOVES ACROSS CANADA NORTH OF THE REGION ON SUNDAY...BRINGING A MIXED BAG OF RAIN AND SNOW SHOWERS DEPENDING ON THE LATITUDE... ELEVATION...AND TIME OF DAY. HIGHS SUNDAY WILL RANGE FROM THE MID 30S NORTH TO THE LOWER 40S SOUTH. AS THE LOW MOVES EAST IT BRINGS ANOTHER BLAST OF COLD IN ITS WAKE...CHANGING THE RAIN TO SNOW SUNDAY EVENING. LOWS SUNDAY NIGHT WILL RANGE FROM THE LOWER TEENS TO THE MID 20S. MONDAY LOOKS TO BE BLUSTERY AND COLD WITH BRISK NORTHWEST WINDS 15 TO 25 MPH DURING THE MIDDAY PERIOD AND HIGHS ONLY FROM AROUND 20 NORTH TO THE UPPER 30S SOUTH. && .AVIATION /15Z TUESDAY THROUGH SATURDAY/... VFR FLIGHT CONDITIONS AND NO AVIATION WEATHER PROBLEMS ARE EXPECTED THROUGH MID TO LATE AFTERNOON. SCATTERED HIGH CLOUDS WILL THICKEN SOME AND LOWER DURING THE MORNING HOURS...WITH AN ALTOSTRATUS DECK AROUND 15000 FT ASL BY MID TO LATE MORNING. WINDS THIS MORNING WILL BE SOUTH 5 TO 10 KNOTS THIS MORNING AND MOST OF THE AFTERNOON. AS A LOW CENTER MOVES FROM THE OHIO VALLEY INTO THE MID ATLANTIC REGION THIS AFTERNOON...CONDITIONS WILL DETERIORATE LATER THIS AFTERNOON...WITH MVFR CONDITIONS AT BEST FOR THE EVENING HOURS AS RAIN OVERSPREADS THE REGION. THE CEILING AND VISIBLITY ARE LIKELY TO LOWER TO IFR DURING THE LATE EVENING HOURS AS THE BOUNDARY LAYER BECOMES MOISTER...WITH WINDS BECOMING SOUTHEAST DURING THE LATE AFTERNOON AND EARLY EVENING. WIDESPREAD IFR MAY BE EXPECTED DURING THE NIGHTTIME HOURS DUE TO LOW CEILINGS AND POOR VISIBILITY. SOME IMPROVEMENT TO MVFR MAY TAKE PLACE LATER TONIGHT AS THE STORM LIFTS NORTH INTO CANADA. LLWS MAY BECOME A FACTOR LATE THIS AFTERNOON AND EVENING AS WINDS 2000 TO 3000 FT AGL INCREASE TO 40-55 KTS. OUTLOOK... WED...MVFR...RAIN MIXING WITH SNOW AND TAPERING OFF TO SHWRS. WINDY. THU...VFR. NO SIG WX. FRI...VFR/MVFR...CHC -SHSN/-SHRA. && .HYDROLOGY... WHILE A SOAKING RAIN OF UP TO AROUND AN INCH IS EXPECTED THROUGH TONIGHT...IT IS NOT EXPECTED TO RESULT IN FLOODING. RAIN IS EXPECTED TO START LATE THIS AFTERNOON AND CONTINUE THROUGH TONIGHT. THE RAIN WILL MIX WITH AND CHANGE TO SNOW WELL NORTH AND WEST OF THE ALBANY AREA. HEAVIEST RAINFALL AMOUNTS ARE EXPECTED IN THE MID HUDSON REGION OF NEW YORK AND OVER THE HOUSATONIC VALLEY AND LITCHFIELD HILLS OF CONNECTICUT. MODEST RISES MAY BE EXPECTED ON THE RIVERS AND STREAMS IN THIS AREA...BUT THE RAIN IS NOT EXPECTED TO BE HEAVY ENOUGH TO BRING RIVERS UP TO FLOOD. DRY WEATHER ON THURSDAY WILL ALLOW RIVERS AND STREAMS TO RECEDE. A SERIES OF CLIPPER TYPE LOWS OVER THE NEW YEARS WEEKEND WILL HAVE LITTLE EFFECT ON THE RIVERS SINCE MOISTURE WILL BE LACKING WITH THEM. 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...GJM/WASULA NEAR TERM...GJM/WASULA SHORT TERM...GJM LONG TERM...RCK AVIATION...RCK HYDROLOGY...RCK
AREA FORECAST DISCUSSION
NWS CHARLESTON SC
706 AM EST TUE DEC 27 2011 .SYNOPSIS... A STRONG LOW PRESSURE SYSTEM WILL LIFT THROUGH THE SE THIS MORNING AND INTO THE CENTRAL APPALACHIANS AND VIRGINIA THIS AFTERNOON. A STRONG COLD FRONT TRAILING FROM THE LOW WILL PASS THROUGH LATE THIS MORNING AND THIS AFTERNOON. THE FRONT WILL BE PRECEDED BY WIDESPREAD SHOWERS AND A FEW STRONGER THUNDERSTORMS...RESULTING IN SOME MUCH NEEDED RAINFALL AND THE POSSIBILITY OF ISOLATED SEVERE WEATHER. HIGH PRESSURE WILL THEN BUILD INTO THE AREA TONIGHT THROUGH THURSDAY. A DRY COLD FRONT MAY MOVE IN LATE FRIDAY...BEFORE HIGH PRESSURE RETURNS FOR SATURDAY. ANOTHER COLD FRONT MAY AFFECT THE AREA EARLY NEXT WEEK. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... A VERY ACTIVE NEAR TERM PERIOD IS ON TAP FOR TODAY WITH MULTIPLE HAZARDS EXPECTED TO AFFECT SOUTHERN SC/SOUTHEAST GA AND THE ADJACENT COASTAL WATERS. OVERALL...THERE ARE NO SIGNIFICANT CHANGES TO THE GENERAL THINKING ABOUT THE UPCOMING EVENT. THE MAIN CHANGES ARE FOR THE TIMING OF THE PRECIP THROUGH THE FORECAST AREA AND FOR UPDATES TO EXPECTED WINDS. AS HAS BEEN WELL DOCUMENTED IN PRECEDING FORECASTS...STRONG SYNOPTIC SCALE FORCING WILL MOVE ACROSS THE REGION TODAY. A POTENT CLOSED UPPER LOW OVER THE LOWER MS VALLEY WILL CONTINUE TO OPEN UP AND PHASE WITH NORTHERN STREAM ENERGY DIVING ACROSS THE UPPER MIDWEST. DIVERGENCE ALOFT ASSOCIATED WITH A 120 KT JET COMBINED WITH STRONG LOW LEVEL LINEAR FORCING ALONG A COLD FRONT WILL IS EXPECTED TO PUSH A BAND OF SHOWERS AND PERHAPS EMBEDDED THUNDERSTORMS ACROSS THE REGION. NOW LETS TAKE A LOOK AT A FEW ASPECTS OF THE EVENT. TIMING OF PRECIP...RECENT OPERATIONAL MODEL RUNS HAVE GREATLY SPED UP THE ARRIVAL OF THE APPROACHING SYSTEM. REGIONAL SATELLITE IMAGERY SHOWS ONGOING PRECIP SURROUNDING THE FORECAST AREA TO THE NW AND W WITH THE MAIN EVENTUAL CONVECTIVE LINE STARTING TO TAKE SHAPE OVER THE NE GULF AND FL PANHANDLE. THE 05Z HRRR SEEMS TO HAVE THE BEST HANDLE ON THE CURRENT PRECIP COVERAGE AND EVOLUTION AND THE POP TREND FOR TODAY GENERALLY FOLLOWS IT. THE PRE FRONTAL LINE OF SHOWERS/CONVECTION WILL BEGIN PUSHING INTO THE FAR WESTERN PORTION OF THE FORECAST AROUND AROUND 12Z. I THEN TAKE THE AREA OF 100 POP AND MARCH IT EASTWARD WITH THE BAND ENTERING THE CHARLESTON AREA IN THE 14-15Z TIME FRAME. THE LINE OF SHOWERS AND/OR THUNDERSTORMS WILL BE PUSHING OFFSHORE BY THE LATE MORNING WITH JUST LINGERING SHOWERS INTO THE EARLY AFTERNOON FOR MOST OF THE AREA. SEVERE WEATHER POTENTIAL...THE DEEP LAYER WIND FIELDS ASSOCIATED WITH THIS SYSTEM CONTINUE TO LOOK QUITE IMPRESSIVE AND A HIGH SHEAR/LOW CAPE ENVIRONMENT IS ANTICIPATED. A POWERFUL 850 MB JET...ON THE ORDER OF 50-60 KTS...WILL TRAVERSE THE AREA THROUGH THE LATE MORNING RESULTING IN 0-3 KM WIND SHEAR OF 50 KTS OR MORE THROUGH THE LATE MORNING HOURS. SHEAR IS NOT THE PROBLEM WITH THIS SYSTEM AND THE LIMITING FACTOR FOR SEVERE WEATHER WILL BE INSTABILITY. GIVEN THAT THE SYSTEM IS EXPECTED TO MOVE THROUGH EARLIER IN THE DAY THAN WITH PREVIOUS FORECASTS...THE TIME WINDOW FOR DESTABILIZATION IS QUITE SHORT. IN FACT...WITH ONGOING PRECIP AND DENSE CLOUD COVER...IT WILL BE DIFFICULT TO GET MUCH IN THE WAY OF SURFACE BASED INSTABILITY. MODELS DO HINT AT A TIME IN THE LATE MORNING WHERE INSTABILITY COULD DEVELOP AND PRIMARILY OVER THE TRI COUNTY AREA AND ALONG THE IMMEDIATE COAST. GIVEN THE STRONGLY SHEARED AND WEAKLY UNSTABLE ENVIRONMENT IN THE PRESENCE OF STRONG LINEAR FORCING...THE PRIMARY CONVECTIVE MODE WOULD BE LINE SEGMENTS CAPABLE OF PRODUCING DAMAGING WIND GUSTS. IN THE EVENT THAT THERE IS ENOUGH INSTABILITY...THERE COULD BE A BRIEF ISOLATED BROKEN S TYPE TORNADO. THE MAIN TIME PERIOD FOR POTENTIAL SEVERE WEATHER LOOKS TO BE BETWEEN 9AM AND 1PM. GUSTY WINDS...AS THE STRENGTHENING LOW LEVEL JET MOVES THROUGH THE AREA STRONG GUSTY WINDS WILL DEVELOP ACROSS PORTIONS OF THE AREA. I HAVE HOISTED A WIND ADVISORY WHICH INCLUDES THE TRI COUNTY AREA AND BEAUFORT/COASTAL COLLETON COUNTIES. MIXING (ALBEIT LIMITED) WILL BEGIN AROUND 13Z JUST AHEAD OF THE APPROACHING PRECIP BAND. AS IT DOES YOU ONLY HAVE TO GO UP TO 500-1000 FEET TO REACH WINDS IN THE 35-40 KT RANGE BASED ON MODEL SOUNDINGS. WIND GUSTS OF 40-45 MPH WILL BE POSSIBLE IN THE AFOREMENTIONED AREAS AND WILL EXTEND THE ADVISORY THROUGH THE LATE AFTERNOON AS WINDS WILL REMAIN ELEVATED IN THE SW TO W FLOW ONCE THE PRECIP BAND PASSES THROUGH. TEMPERATURES WILL CONTINUE TO RISE THIS MORNING AS A WARM FRONT PASSES THROUGH DURING THE NEXT FEW HOURS. UPPER 60S CAN BE EXPECTED RIGHT ALONG THE COAST FROM SAVANNAH TO CHARLESTON WITH LOW TO MID 60S FURTHER INLAND. && .SHORT TERM /6 PM THIS EVENING THROUGH FRIDAY/... TONIGHT...DEEP LOW PRESSURE OVER THE NE CONTINUES TO STRENGTHEN AS IT MOVES INTO SE CANADA OVERNIGHT. THE TRAILING COLD FRONT WILL HAVE SHIFTED INTO THE ATLANTIC BY NIGHTFALL OFF OUR COASTS...AND HIGH PRESSURE WILL STEADILY BUILD FROM THE WEST THROUGH THE NIGHT. STRONG COLD ADVECTION EARLY WILL SLACKEN OFF AFTER MIDNIGHT...KEEPING BREEZY CONDITIONS GOING UNTIL LATE EVENING OR THE OVERNIGHT HOURS. AS SKIES CLEAR OUT...TEMPS WILL DROP STEADILY...BOTTOMING OUT BETWEEN 35 AND 40 DEGREES MOST LOCALES. LAKE WINDS...ONCE THE WIND ADVISORY COMES DOWN FOR BERKELEY COUNTY IT WILL NEED TO BE REPLACED BY A WIND ADVISORY ON LAKE MOULTRIE TONIGHT...AS COLD ADVECTION MOVING ACROSS THE WARMER LAKE WATERS WILL ALLOW FOR GOOD MIXING OF 20-30 KT WITHIN THE BOUNDARY LAYER. WEDNESDAY...A DRY WEST TO NW FLOW PREVAILS ALOFT...AS HIGH PRESSURE AT THE SURFACE MOVES IN FROM THE WEST. WEAK COLD ADVECTION IN THE MORNING WILL BE OFFSET BY DOWNSLOPE FLOW OFF THE MOUNTAINS AND PLENTY OF SUNSHINE...BUT WITH 850 MB TEMPS ONLY AROUND 2-3C NORTH AND 4-5C SOUTH...WE LOOK FOR MAX TEMPS MAINLY IN THE UPPER 50S. WEDNESDAY NIGHT IS THEN THE COLDEST NIGHT OF THE FORECAST PERIOD...AS THE HIGH SHIFTS CLOSER TO THE AREA AND GEOSTROPHIC WINDS FALL TO UNDER 10 KT. THIS ALLOWS FOR EXCELLENT RADIATIONAL COOLING AND WILL RESULT IN MIN TEMPS 30-35 INLAND FROM US-17...AND CLOSER TO 40 NEAR THE COAST. THURSDAY...HIGH PRESSURE SLIPS A LITTLE SOUTH AS A CLIPPER TYPE LOW PRESSURE SYSTEM MOVES THROUGH THE GREAT LAKES REGION. AFTER THE CHILLY START...ABUNDANT SUNSHINE AND DOWNSLOPE FLOW OFF THE APPALACHIANS WILL ALLOW FOR US TO TOP OUT WITHIN A COUPLE OF DEGREES EITHER SIDE OF 60. FRIDAY...AS THE LOW TO THE NORTH PUSHES EAST...A TRAILING COLD FRONT WILL MOVE APPROACH LATE IN THE DAY. BUT GIVEN THAT THE FLOW ALOFT IS GENERAL ZONAL AND ANY SHORT WAVE ENERGY REMAINS NORTH...THE FRONT LOOKS TO COME THROUGH DRY. COMPRESSIONAL HEATING AHEAD OF THE FRONT...AND OFFSHORE FLOW AND 850 MB TEMPS CLIMBING TO NEAR 9-10 C WILL BOOST AFTERNOON READINGS TO THE LOWER AND MIDDLE 60S. && .LONG TERM /FRIDAY NIGHT THROUGH MONDAY/... QUASI-ZONAL FLOW OR EVEN SHORT WAVE RIDGING ALOFT WILL PREVAIL LATE THIS WEEK...BEFORE THE PATTERN SHOWS SIGNS OF CHANGING EARLY NEXT WEEK. THE MID/UPPER SLOW WILL SEE THE FORMATION OF A TROUGH IN THE EAST AND RIDGING OUT WEST. THIS WILL ALLOW FOR SOME COLDER AIR TO INVADE THE EASTERN UNITED STATES...BUT TO WHAT MAGNITUDE HAS YET TO BE DETERMINED. AS THE PATTERN ALOFT TRANSITIONS OVER WE WILL SEE A COLD FRONT MOVING THROUGH EARLY NEXT WEEK...ALTHOUGH THERE ARE SOME TIMING UNCERTAINTIES AND AS TO WHETHER OR NOT IT WILL COME THROUGH DRY OR WITH SOME PRECIP. FOR NOW WE PREFER TO KEEP A DRY FORECAST GOING THROUGH TUESDAY...CAPPING POPS EARLY NEXT WEEK AT A SILENT 14 PERCENT. TEMPS WILL BE ABOVE NORMAL THROUGH THE WEEKEND...THEN TREND TOWARD BELOW NORMAL LEVELS MONDAY AND TUESDAY OR NEXT WEEK. && .AVIATION /12Z TUESDAY THROUGH SATURDAY/... VFR CONDITIONS EARLY IN THE TAF PERIOD WILL GIVE WAY TO PREVAILING MVFR WEATHER STARTING AROUND 1330-1430Z AT THE TERMINALS. THIS WILL RESULT FROM A WIDE BAND OF SHRA AND POSSIBLE TSRA IN ADVANCE OF A STRONG COLD FRONT THAT PUSHES THROUGH EARLY THIS AFTERNOON. IFR CONDITIONS CANNOT BE RULED OUT...BUT PROBABILITIES FAVOR MVFR WEATHER WILL PREVAIL. VFR CONDITIONS THEN RETURN IN WAKE OF THE COLD FRONT BEGINNING AROUND 1730-1830Z...AND WILL REMAIN VFR THROUGH 12Z WEDNESDAY. WINDS WILL BE OF GREAT CONCERN TODAY INTO TONIGHT WITH THE PASSAGE OF A STRONG LOW LEVEL JET...AS HIGH AS 45-55 KT THIS MORNING...AND 30-40 KT THIS AFTERNOON INTO TONIGHT. AS SUCH...BOTH TERMINALS WILL EXPERIENCE EITHER WIND SHEAR AND/OR STRONG GUSTY WINDS THROUGH MOST IF NOT THE ENTIRE TAF PERIOD. EXTENDED AVIATION OUTLOOK...VFR CONDITIONS WILL PREVAIL. && .MARINE... TODAY...AN AREA OF LOW PRESSURE WILL MOVE NORTHWARD INTO THE CENTRAL APPALACHIANS WITH A STRONG COLD FRONT MOVING INTO THE REGION THIS MORNING. AS IT DOES SO...A POWERFUL LOW LEVEL JET WITH PUSH ACROSS THE LOCAL WATERS SETTING UP THE CONDITIONS FOR A STRONG WIND EVENT. AFTER ANALYZING MODEL SOUNDINGS FOR THE LOCAL WATERS...CONFIDENCE HAS INCREASED SUFFICIENTLY TO UPGRADE THE SCA/S TO GALE WARNINGS FOR THE OUTER GA WATERS...THE NEARSHORE CHARLESTON WATERS...AND THE CHARLESTON HARBOR. FREQUENT GUSTS TO 35 KTS CAN BE EXPECTED IN THESE AREAS BEGINNING JUST AFTER SUNRISE AND CONTINUING THROUGH THE DAY. CONDITIONS WILL BE CLOSE TO GALE WARNING CRITERIA FOR THE REMAINDER OF THE NEARSHORE WATERS BUT CONFIDENCE ISN/T AS HIGH THERE. CONDITIONS WILL NEED TO MONITORED FOR POSSIBLE UPGRADES TO AMZ 352 AND 354. WINDS JUST AHEAD OF THE MAIN PRECIP BAND BE OUT OF THE S...WITH SOME EVEN HIGHER GUSTS POSSIBLE IN ANY THUNDERSTORMS THE DEVELOP WITHIN THE BAND. THE MAIN AREA OF PRECIP SHOULD CLEAR MOST OF THE WATERS BY THE EARLY AFTERNOON AND WINDS WILL BECOME MORE SW BEHIND IT. SEAS WILL BUILD THROUGH THE DAY AND WILL REACH UP TO 8 FEET CLOSE TO 20 NM ACROSS THE NEARSHORE CHARLESTON WATERS. CONCERNING A POSSIBLE HIGH SURF ADVISORY...IT STILL LOOKS LIKE THE DURATION OF SOUTHERLY FETCH WILL BE TOO SHORT TO MAKE AN ADVISORY NECESSARY. TONIGHT...COLD ADVECTION WILL INTENSIFY IN WAKE OF THE COLD FRONT AND DEPARTING LOW TO THE DISTANT NORTH...AND WE ARE LOOKING AT SOLID SCA/S FOR ALL WATERS FROM 0-20 NM AND IN THE CHARLESTON HARBOR. IT/LL BE CLOSE TO GALES ACROSS THESE WATERS...BUT IT LOOKS LIKE ANY FREQUENCY OF GUSTS WILL BE CLOSER TO 30 KT RATHER THAN 35 KT. ACROSS THE OUTER GA WATERS...ANY DECREASE IN WINDS THIS EVENING WILL ONLY BE TEMPORARY AS EXCELLENT MIXING ALLOWS FOR GALE FORCE GUSTS TO AGAIN ARRIVE ACROSS AMZ374. THE OFFSHORE FETCH WILL ALLOW FOR SEAS TO REMAIN UNDER 5 OR 6 FT WITHIN 20 NM OF SHORE...BUT WILL STILL REACH AS HIGH AS 8 OR 9 FT OUT NEAR 60 NM OFFSHORE. WEDNESDAY...MARINE CONDITIONS WILL RAPIDLY IMPROVE DURING THE MORNING AS COLD ADVECTION WANES AND THE PRESSURE GRADIENT BEGINS TO RELAX AS HIGH PRESSURE BUILDS IN FROM THE WEST. ALL HEADLINES WILL COME DOWN BY NO LATER THAN 10-11 AM. THURSDAY THROUGH FRIDAY...RELATIVELY QUIET CONDITIONS WILL PREVAIL WITH HIGH PRESSURE OVER OR JUST SOUTH OF THE MARINE AREA...AND A MAINLY OFFSHORE FLOW TO PREVAIL. A COLD FRONT LOOKS TO MOVE THROUGH LATE FRIDAY OR FRIDAY NIGHT. WINDS AND SEAS WILL BE NOWHERE NEAR ANY SCA CRITERIA. SATURDAY THROUGH SUNDAY...HIGH PRESSURE WILL BUILD FROM THE NORTH...AND THEN SLIDES EAST INTO THE ATLANTIC. ALTHOUGH AN OFFSHORE FLOW DEVELOPS...WIND SPEEDS WILL REACH NO MORE THAN 10 OR 15 KT...AND SEAS WILL BE LIMITED TO ONLY 2 OR 3 FT. MONDAY THROUGH TUESDAY...IT LOOKS LIKE ANOTHER COLD FRONT WILL IMPACT THE AREA EARLY NEXT WEEK...FOLLOWED BY STRONG HIGH PRESSURE FROM THE WEST AND NW. WINDS AND SEAS WILL RISE...AND ALTHOUGH PROBABILITIES ARE LOW...WE CAN/T RULE OUT THE POSSIBILITY OF SOME SCA/S WITHIN THE COLDER AIR REGIME. && .TIDES/COASTAL FLOODING... THE MORNING HIGH TIDE IN CHARLESTON WILL COME VERY CLOSE TO THE SHALLOW COASTAL FLOODING CRITERIA OF 7.0 FT MLLW. RECENT TRENDS OF THE TIDAL DEPARTURE SHOWS THAT LEVELS ARE RUNNING NEAR OR A LITTLE ABOVE 1.0 FT MLLW ABOVE PREDICTED. WITH THE PREDICTED TIDE OF 6.04 FT AT 944 AM...WE HAVE OPTED TO ISSUE A COASTAL FLOOD ADVISORY UNTIL 11 AM FOR CHARLESTON AND COASTAL COLLETON COUNTIES. && .CHS WATCHES/WARNINGS/ADVISORIES... GA...NONE. SC...WIND ADVISORY UNTIL 5 PM EST THIS AFTERNOON FOR SCZ044-045- 048>050-052. COASTAL FLOOD ADVISORY UNTIL 11 AM EST THIS MORNING FOR SCZ049- 050. MARINE...SMALL CRAFT ADVISORY UNTIL 7 AM EST WEDNESDAY FOR AMZ352. GALE WARNING UNTIL 5 PM EST THIS AFTERNOON FOR AMZ330-350. SMALL CRAFT ADVISORY UNTIL 4 AM EST WEDNESDAY FOR AMZ354. GALE WARNING UNTIL 4 AM EST WEDNESDAY FOR AMZ374. && $$
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
812 AM CST TUE DEC 27 2011 .DISCUSSION... 330 AM CST THE FORECAST CHALLENGES ARE FIRST ON THE IMMEDIATE SHORT TERM WITH PRECIPITATION GRADUALLY SHIFTING EASTWARD THIS MORNING...THEN THE LAKE EFFECT SHOWER POTENTIAL INTO NORTHWEST INDIANA THIS AFTERNOON AND EVENING. THE ACTIVE FLOW PATTERN ACROSS THE NORTHERN U.S. AND SOME UNDULATIONS IN THIS INTO THE NEW YEAR KEEP THE FORECAST INTERESTING LOOKING FORWARD. SHORT TERM...LOW PRESSURE IS DEVELOPING FAIRLY RAPIDLY UNDER STRONG JET SUPPORT ACROSS WESTERN KY. MOIST ADVECTION ALOFT AND ASSOCIATED ASCENT CONTINUES TO WORK ITS WAY ACROSS NORTHWEST INDIANA. AN ELONGATED NORTHERN STREAM WAVE PUSHING EAST ACROSS THE REGION HAS INTERACTED WITH THIS...HELPING TO PRODUCE BANDS OF MODERATE PRECIP AT TIMES WHERE CONVERGENCE OF ECHOES WAS OBSERVED /AND LIKELY IMPLYING FRONTOGENETIC FORCING/. WITHIN THESE...A FEW REPORTS OF SLEET WERE OBSERVED/REPORTED OR ESTIMATED THROUGH UNKNOWN PRECIP AUTOMATED REPORTS. STRONGER FORCING LIFTING NORTH ACROSS EASTERN IL/WESTERN IN HAS HELPED TO LEAD TO EVAPORATIONAL COOLING SUPPORTING SNOW...AND BENTON COUNTY REPORTED A COATING OF SNOW ON THEIR PAVEMENT AS OF 300 AM. EXPECT THE AREAS RECEIVING PRECIPITATION AT DAYBREAK TO BE MAINLY A WET SNOW...WITH A LITTLE LIGHT RAIN POSSIBLY JUST BEFORE IT ENDS ON THE WESTERN PERIPHERY. THE SHIELD OF PRECIP WILL TAKE A WHILE TO EVOLVE EAST OUT OF THE AREA BASED ON THE QG FORCING ON THE RUC AS WELL AS WATER VAPOR TRENDS WITH THE DRY SLOT NOSE LIFTING INTO CENTRAL IN HELPING TO KEEP MAINLY SNOW GOING IN THE SOUTHEAST FORECAST AREA THIS MORNING. MAXIMUM ACCUMULATIONS NEAR AN INCH TOWARDS FOWLER AND RENSSALEAR STILL LOOK VALID. IN THE FAR SOUTH AND SOUTHEAST CHICAGO METRO WHILE SNOW MAY STILL BE OCCURRING THROUGH 9 AM OR SO...NO ACCUMULATION IS EXPECTED. THIS AFTERNOON...STRONG NORTH TO NORTHWEST WINDS IN THE WAKE OF THE SYSTEM ESTABLISH THEMSELVES DOWN THE FETCH OF LAKE MI THIS AFTERNOON. CONVERGENCE STREAMLINES FROM THE 27.06 NAM FAVOR A CORRIDOR OF SATURATED CONVERGENCE CENTERED ON MICHIGAN CITY...WITH SOME FURTHER WEST TOWARDS PORTER COUNTY. LAKE INDUCED EQUILIBRIUM LEVELS ARE PROJECTED OVER 5000 FT ON THE NAM FOR LATE THIS AFTERNOON AND EVENING AND THUS HAVE INCREASED POPS IN THAT AREA FOR SOME SNOW SHOWERS. FROM THIS...ONLY AN ADDITIONAL DUSTING IS EXPECTED WITH POTENTIAL FOR MORE JUST EAST OF THE FORECAST AREA. TONIGHT THROUGH THURSDAY...THE TEMPERATURES TONIGHT WILL BE A BATTLE BETWEEN THE COLD AND DRY AIR ADVECTION THIS EVENING AND THEN MID TO HIGH CLOUDS ON THE INCREASE FROM THE WEST OVERNIGHT WITH AN APPROACHING SHORT WAVE. IN ADDITION...LINGERING STRATOCU IN THE CAA REGIME IS LIKELY EARLY THIS EVENING...AND THAT MAY RESIDE THROUGH A GOOD PART OF THE NIGHT IN EASTERN AREAS. MODEL SPREAD REFLECTS THIS...VARYING UP TO TEN DEGREES IN SOME LOCATIONS. CONFIDENCE IS THUS MINIMAL ON TONIGHTS LOWS...AND AM NEAR THE CENTER OF THE SPREAD AT THIS TIME. A STRONGER SHORT WAVE ARRIVES INTO SOUTHERN WI ON LATE WEDNESDAY NIGHT INTO THURSDAY MORNING. THIS IS A TRUE QUICK MOVING CLIPPER...WITH ITS BEST MOISTURE SUPPORT ALONG AND NORTH OF ITS PATH WHERE THE TIGHT MID- LEVEL THERMAL GRADIENT EXISTS. WHILE THERE IS FAIRLY STOUT 850-600 MB WAA AHEAD OF THIS FEATURE WED AFTERNOON AND EVENING...THE COLUMN LOOKS MUCH TOO DRY FOR PRECIP. SO ONLY HAVE POPS NEAR THE WI STATE LINE WITH THE ACTUAL LOW CENTER PASSAGE. THURSDAY NIGHT...WHAT HAD BEEN A DEEP SLOW-MOVING LOW IN THE LONGER RANGE FORECAST DAYS AGO HAS TRENDED TOWARDS A SHARP SOUTHEAST DIVING CLIPPER THAT STILL IS FAIRLY DEEP IN PRESSURE FOR CLIPPERS /~1002 MB/. THE PATH ON THE GFS AND EC FAVOR OUR AREA TO SEE SOME PRECIP...BUT EVEN A SLIGHT SHIFT NORTH OR SOUTH WOULD GREATLY REDUCE THEM AS IT IS A FAIRLY NARROW AXIS OF PRECIP WITH SUCH A STRUCTURE. INDEED THE 27.06 NAM IS A SOLUTION THAT IS FURTHER NORTH WITH LITTLE QPF. THE EC FOR TWO CONSECUTIVE RUNS HAS BEEN SLOWER THAN THE GFS...FAVORING OVERNIGHT THU AS OPPOSED TO THE EVE FOR INFLUENCE OVER OUR AREA. BOTH MODELS WOULD STILL SUPPORT SNOW CHANCES...BUT THE EC IS BETTER LOOKING FOR THAT WITH SLIGHTLY DEEPER HEIGHT FALLS AND GREATER MIXING RATIOS ON THE LIFTING SURFACES / 2.5-3 G/KG /. UNFORTUNATELY...THIS WAVE IS ONE OF MANY IN THE NORTHERN PACIFIC RIGHT NOW AND THUS NOT WELL SAMPLED. SO HAVE KEPT POPS ONLY AT A CHANCE BUT HAVE INCREASE VALUES. BEYOND...THE PROGRESSIVE PATTERN CONTINUES WITH AN IMMEDIATE INCREASE IN HEIGHTS AND A LOW-LEVEL THERMAL RIDGE INTO THE AREA. THE GFS...EC...AND GEM ALL BRING 850 MB TEMPERATURES TO ABOVE 8C ON SATURDAY. BIAS-CORRECTED FORECASTS FROM THESE MODELS BLENDED TOGETHER YIELDS HIGHS FROM THE UPPER 40S TO A STAGGERING MID 50S. WITH SUCH A QUICK TURNAROUND FROM COOL AIR ADVECTION BEHIND THE WAVE THURSDAY NIGHT/EARLY FRIDAY...WILL NOT BE GOING THAT HIGH. BUT HAVE BLENDED THE GOING FORECAST ALMOST 50 PERCENT WITH THESE. THIS AMPLIFIED PATTERN WHICH BRINGS IN THE WARMER REGIME IS AHEAD OF A DIGGING JET TO START THE NEW YEAR WHICH HAS BEEN HINTED AT IN SOLUTIONS FOR A WHILE. THIS WOULD AT LEAST BRING TEMPERATURES DOWN FOR EARLY NEXT WEEK...BUT CONFIDENCE IS LOW IN THIS AS WELL AS THE PRECIP CHANCES WITH THE SYSTEM EVOLVING ON THE JET UNDULATION. LOOKING INTO NEXT WEEK...DESPITE THE CHANCES FOR COOLER TEMPERATURES INITIALLY...THE 8 TO 14 DAY CPC OUTLOOK AND ESPECIALLY THE NAEFS MEMBERS FAVOR ABOVE NORMAL TEMPERATURES IN GENERAL. MTF && .AVIATION... //ORD AND MDW CONCERNS...UPDATED 14Z... * CIG TRENDS THIS MORNING AND AFTERNOON...TIMING WINDOW OF VFR CONDITIONS BEFORE HIGHER END MVFR CONDITIONS RETURN. * STRONG GUSTY NNW WINDS. * POSSIBILITY OF FLURRIES THIS AFTERNOON. BMD //DISCUSSION...UPDATED 12Z... AREAS OF RAIN AND MIXED RAIN/SNOW OVER THE CHICAGO METRO TERMINALS HAVE DECREASED IN SIZE AND MOVED TO THE EAST THROUGH THE EARLY MORNING HOURS AS THE LOW PRESSURE SYSTEM CENTERED OVER WESTERN KY MOVES TO THE NORTHEAST. AS THE PRECIPITATION ENDS CIGS MAY IMPROVE JUST A LITTLE BIT. BUT MORE SIGNIFICANT IMPROVEMENT WILL BE BEHIND A COLD FRONT THAT WILL MOVE ACROSS NORTHERN IL AND NORTHWEST IN THIS MORNING. THIS FRONT WILL TURN WINDS TO THE NORTHWEST AND INCREASE THE SPEEDS BY LATE MORNING. FLURRIES ARE POSSIBLE BEHIND THE FRONT IN THE COLDER AIR AT ALL THE TERMINALS THIS AFTERNOON. PAW //ORD AND MDW CONFIDENCE...UPDATED 14Z... * MEDIUM CONFIDENCE ON SOME WINDOW OF IFR CONDITIONS...LOW CONFIDENCE ON SPECIFIC TIMING. * HIGH CONFIDENCE THAT ONCE CIGS LIFT ABOVE 015...WILL STAY ABOVE 015. * HIGH CONFIDENCE ON WIND DIRECTION...MEDIUM CONFIDENCE ON WIND SPEEDS/GUSTS. * LOW CONFIDENCE ON FLURRIES THIS AFTERNOON. BMD //OUTLOOK FOR ORD/MDW FOR 00Z THURSDAY-12Z TUESDAY...UPDATED 12Z... * WEDNESDAY NIGHT...VFR. * THURSDAY...VFR. SLIGHT CHANCE OF LIGHT RAIN...POSSIBLY MIXING WITH LIGHT SNOW. * FRIDAY...MVFR POSSIBLE. SLIGHT CHANCE OF LIGHT RAIN OR LIGHT SNOW. * SATURDAY...VFR. * SUNDAY...SLIGHT CHANCE OF LIGHT RAIN OR LIGHT SNOW. * MONDAY...SLIGHT CHANCE OF LIGHT SNOW. PAW && .MARINE... 235 AM CST AN AREA OF LOW PRESSURE CONTINUES TO SLOWLY MOVE EAST ACROSS SOUTHERN ONTARIO THIS MORNING. DRAPED SOUTH FROM THIS LOW AND SPANNING MUCH OF THE UPPER AND MIDDLE MISSISSIPPI VALLEY IS A COLD FRONT THAT WILL SLIDE ACROSS THE LAKE LATER THIS MORNING. AHEAD OF IT...THE 15 TO 25 KT WINDS WILL VEER TO THE WEST AND THEN TO THE NORTHWEST THROUGH THE EARLY AFTERNOON HOURS. THE STRONGEST SURGE OF COLD AIR IS NOT ANTICIPATED TO BE UNTIL THE LATER AFTERNOON HOURS FOR THE NORTHERN HALF OF THE LAKE...AND SHORTLY THEREAFTER FOR THE SOUTHERN HALF. IT IS WITH THIS SURGE THAT THE STRONGEST OF WINDS IS ANTICIPATED. HIGH END GALES ARE AGAIN LIKELY...BUT FOR THE ENTIRE SPAN OF THE LAKE WITH THIS EVENT AS OPPOSED TO THE STRONGEST WINDS REMAINING NORTH YESTERDAY. FORECAST SOUNDINGS ARE ALSO INDICATING THE POTENTIAL FOR LOW END STORM FORCE GUSTS. FEEL THAT THE MAJORITY OF THE WINDS WILL REMAIN BELOW STORM CRITERIA FOR THE OPEN WATERS AND WILL ONLY MENTION IN AN OCCASIONAL GROUP. THOUGHTS THEN TURN TO NEARSHORE BURNS HARBOR TO MICHIGAN CITY IN AND 744...AND POTENTIALLY 743 AND GALES. WITH THE STRONG NORTHWESTERLY WINDS EXPECTED...INCREASES THE CHANCES INTO THE EVENING HOURS AND OVERNIGHT. WILL ERR ON THE SIDE OF CAUTION FOR THE FRICTIONLESS MARINE LOCATIONS AND CANCEL THE SMALL CRAFT FOR THOSE LOCATIONS AND HOIST A GALE WARNING. CONDITIONS SET TO IMPROVE LATE TONIGHT AS RIDGING ACROSS THE SURFACE BUILDS...THOUGH PROLONGED STRONG SOUTHWESTERLY FLOW WILL SLOWLY RAMP UP THROUGH WEDNESDAY NIGHT...WITH FLOW PROGGED TO REMAIN BELOW GALE. SHEA && .LOT WATCHES/WARNINGS/ADVISORIES... IL...NONE. IN...NONE. LM...SMALL CRAFT ADVISORY...NEARSHORE GARY TO MICHIGAN CITY IN UNTIL NOON TUESDAY. GALE WARNING...LMZ080-LMZ261-LMZ362-LMZ364-LMZ366-LMZ563-LMZ565- LMZ567-LMZ669-LMZ671-LMZ673-LMZ675-LMZ744-LMZ745-LMZ777- LMZ779-LMZ868-LMZ870-LMZ872-LMZ874-LMZ876-LMZ878...NOON TUESDAY TO 3 AM WEDNESDAY. SMALL CRAFT ADVISORY...NEARSHORE WINTHROP HARBOR TO GARY IN UNTIL 6 PM WEDNESDAY. && $$
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
533 AM CST TUE DEC 27 2011 .DISCUSSION... 330 AM CST THE FORECAST CHALLENGES ARE FIRST ON THE IMMEDIATE SHORT TERM WITH PRECIPITATION GRADUALLY SHIFTING EASTWARD THIS MORNING...THEN THE LAKE EFFECT SHOWER POTENTIAL INTO NORTHWEST INDIANA THIS AFTERNOON AND EVENING. THE ACTIVE FLOW PATTERN ACROSS THE NORTHERN U.S. AND SOME UNDULATIONS IN THIS INTO THE NEW YEAR KEEP THE FORECAST INTERESTING LOOKING FORWARD. SHORT TERM...LOW PRESSURE IS DEVELOPING FAIRLY RAPIDLY UNDER STRONG JET SUPPORT ACROSS WESTERN KY. MOIST ADVECTION ALOFT AND ASSOCIATED ASCENT CONTINUES TO WORK ITS WAY ACROSS NORTHWEST INDIANA. AN ELONGATED NORTHERN STREAM WAVE PUSHING EAST ACROSS THE REGION HAS INTERACTED WITH THIS...HELPING TO PRODUCE BANDS OF MODERATE PRECIP AT TIMES WHERE CONVERGENCE OF ECHOES WAS OBSERVED /AND LIKELY IMPLYING FRONTOGENETIC FORCING/. WITHIN THESE...A FEW REPORTS OF SLEET WERE OBSERVED/REPORTED OR ESTIMATED THROUGH UNKNOWN PRECIP AUTOMATED REPORTS. STRONGER FORCING LIFTING NORTH ACROSS EASTERN IL/WESTERN IN HAS HELPED TO LEAD TO EVAPORATIONAL COOLING SUPPORTING SNOW...AND BENTON COUNTY REPORTED A COATING OF SNOW ON THEIR PAVEMENT AS OF 300 AM. EXPECT THE AREAS RECEIVING PRECIPITATION AT DAYBREAK TO BE MAINLY A WET SNOW...WITH A LITTLE LIGHT RAIN POSSIBLY JUST BEFORE IT ENDS ON THE WESTERN PERIPHERY. THE SHIELD OF PRECIP WILL TAKE A WHILE TO EVOLVE EAST OUT OF THE AREA BASED ON THE QG FORCING ON THE RUC AS WELL AS WATER VAPOR TRENDS WITH THE DRY SLOT NOSE LIFTING INTO CENTRAL IN HELPING TO KEEP MAINLY SNOW GOING IN THE SOUTHEAST FORECAST AREA THIS MORNING. MAXIMUM ACCUMULATIONS NEAR AN INCH TOWARDS FOWLER AND RENSSALEAR STILL LOOK VALID. IN THE FAR SOUTH AND SOUTHEAST CHICAGO METRO WHILE SNOW MAY STILL BE OCCURRING THROUGH 9 AM OR SO...NO ACCUMULATION IS EXPECTED. THIS AFTERNOON...STRONG NORTH TO NORTHWEST WINDS IN THE WAKE OF THE SYSTEM ESTABLISH THEMSELVES DOWN THE FETCH OF LAKE MI THIS AFTERNOON. CONVERGENCE STREAMLINES FROM THE 27.06 NAM FAVOR A CORRIDOR OF SATURATED CONVERGENCE CENTERED ON MICHIGAN CITY...WITH SOME FURTHER WEST TOWARDS PORTER COUNTY. LAKE INDUCED EQUILIBRIUM LEVELS ARE PROJECTED OVER 5000 FT ON THE NAM FOR LATE THIS AFTERNOON AND EVENING AND THUS HAVE INCREASED POPS IN THAT AREA FOR SOME SNOW SHOWERS. FROM THIS...ONLY AN ADDITIONAL DUSTING IS EXPECTED WITH POTENTIAL FOR MORE JUST EAST OF THE FORECAST AREA. TONIGHT THROUGH THURSDAY...THE TEMPERATURES TONIGHT WILL BE A BATTLE BETWEEN THE COLD AND DRY AIR ADVECTION THIS EVENING AND THEN MID TO HIGH CLOUDS ON THE INCREASE FROM THE WEST OVERNIGHT WITH AN APPROACHING SHORT WAVE. IN ADDITION...LINGERING STRATOCU IN THE CAA REGIME IS LIKELY EARLY THIS EVENING...AND THAT MAY RESIDE THROUGH A GOOD PART OF THE NIGHT IN EASTERN AREAS. MODEL SPREAD REFLECTS THIS...VARYING UP TO TEN DEGREES IN SOME LOCATIONS. CONFIDENCE IS THUS MINIMAL ON TONIGHTS LOWS...AND AM NEAR THE CENTER OF THE SPREAD AT THIS TIME. A STRONGER SHORT WAVE ARRIVES INTO SOUTHERN WI ON LATE WEDNESDAY NIGHT INTO THURSDAY MORNING. THIS IS A TRUE QUICK MOVING CLIPPER...WITH ITS BEST MOISTURE SUPPORT ALONG AND NORTH OF ITS PATH WHERE THE TIGHT MID- LEVEL THERMAL GRADIENT EXISTS. WHILE THERE IS FAIRLY STOUT 850-600 MB WAA AHEAD OF THIS FEATURE WED AFTERNOON AND EVENING...THE COLUMN LOOKS MUCH TOO DRY FOR PRECIP. SO ONLY HAVE POPS NEAR THE WI STATE LINE WITH THE ACTUAL LOW CENTER PASSAGE. THURSDAY NIGHT...WHAT HAD BEEN A DEEP SLOW-MOVING LOW IN THE LONGER RANGE FORECAST DAYS AGO HAS TRENDED TOWARDS A SHARP SOUTHEAST DIVING CLIPPER THAT STILL IS FAIRLY DEEP IN PRESSURE FOR CLIPPERS /~1002 MB/. THE PATH ON THE GFS AND EC FAVOR OUR AREA TO SEE SOME PRECIP...BUT EVEN A SLIGHT SHIFT NORTH OR SOUTH WOULD GREATLY REDUCE THEM AS IT IS A FAIRLY NARROW AXIS OF PRECIP WITH SUCH A STRUCTURE. INDEED THE 27.06 NAM IS A SOLUTION THAT IS FURTHER NORTH WITH LITTLE QPF. THE EC FOR TWO CONSECUTIVE RUNS HAS BEEN SLOWER THAN THE GFS...FAVORING OVERNIGHT THU AS OPPOSED TO THE EVE FOR INFLUENCE OVER OUR AREA. BOTH MODELS WOULD STILL SUPPORT SNOW CHANCES...BUT THE EC IS BETTER LOOKING FOR THAT WITH SLIGHTLY DEEPER HEIGHT FALLS AND GREATER MIXING RATIOS ON THE LIFTING SURFACES / 2.5-3 G/KG /. UNFORTUNATELY...THIS WAVE IS ONE OF MANY IN THE NORTHERN PACIFIC RIGHT NOW AND THUS NOT WELL SAMPLED. SO HAVE KEPT POPS ONLY AT A CHANCE BUT HAVE INCREASE VALUES. BEYOND...THE PROGRESSIVE PATTERN CONTINUES WITH AN IMMEDIATE INCREASE IN HEIGHTS AND A LOW-LEVEL THERMAL RIDGE INTO THE AREA. THE GFS...EC...AND GEM ALL BRING 850 MB TEMPERATURES TO ABOVE 8C ON SATURDAY. BIAS-CORRECTED FORECASTS FROM THESE MODELS BLENDED TOGETHER YIELDS HIGHS FROM THE UPPER 40S TO A STAGGERING MID 50S. WITH SUCH A QUICK TURNAROUND FROM COOL AIR ADVECTION BEHIND THE WAVE THURSDAY NIGHT/EARLY FRIDAY...WILL NOT BE GOING THAT HIGH. BUT HAVE BLENDED THE GOING FORECAST ALMOST 50 PERCENT WITH THESE. THIS AMPLIFIED PATTERN WHICH BRINGS IN THE WARMER REGIME IS AHEAD OF A DIGGING JET TO START THE NEW YEAR WHICH HAS BEEN HINTED AT IN SOLUTIONS FOR A WHILE. THIS WOULD AT LEAST BRING TEMPERATURES DOWN FOR EARLY NEXT WEEK...BUT CONFIDENCE IS LOW IN THIS AS WELL AS THE PRECIP CHANCES WITH THE SYSTEM EVOLVING ON THE JET UNDULATION. LOOKING INTO NEXT WEEK...DESPITE THE CHANCES FOR COOLER TEMPERATURES INITIALLY...THE 8 TO 14 DAY CPC OUTLOOK AND ESPECIALLY THE NAEFS MEMBERS FAVOR ABOVE NORMAL TEMPERATURES IN GENERAL. MTF && .AVIATION... //ORD AND MDW CONCERNS...UPDATED 12Z... * TIMING OF PRECIPITATION ENDING AT MDW THIS MORNING. * POSSIBILITY OF FLURRIES THIS AFTERNOON. * IFR CIGS IMPROVING TO MVFR BY MID MORNING. * WIND SHIFT TO NORTHWEST MID MORNING. SPEED INCREASING AND BECOMING GUSTY BY LATE MORNING AND CONTINUING INTO THIS EVENING. PAW //DISCUSSION...UPDATED 12Z... AREAS OF RAIN AND MIXED RAIN/SNOW OVER THE CHICAGO METRO TERMINALS HAVE DECREASED IN SIZE AND MOVED TO THE EAST THROUGH THE EARLY MORNING HOURS AS THE LOW PRESSURE SYSTEM CENTERED OVER WESTERN KY MOVES TO THE NORTHEAST. AS THE PRECIPITATION ENDS CIGS MAY IMPROVE JUST A LITTLE BIT. BUT MORE SIGNIFICANT IMPROVEMENT WILL BE BEHIND A COLD FRONT THAT WILL MOVE ACROSS NORTHERN IL AND NORTHWEST IN THIS MORNING. THIS FRONT WILL TURN WINDS TO THE NORTHWEST AND INCREASE THE SPEEDS BY LATE MORNING. FLURRIES ARE POSSIBLE BEHIND THE FRONT IN THE COLDER AIR AT ALL THE TERMINALS THIS AFTERNOON. PAW //ORD AND MDW CONFIDENCE...UPDATED 12Z... * MEDIUM CONFIDENCE IN ALL PRECIPITATION. * MEDIUM CONFIDENCE IN TIMING OF IFR CIG IMPROVEMENT. * HIGH CONFIDENCE IN WIND TREND. PAW //OUTLOOK FOR ORD/MDW FOR 00Z THURSDAY-12Z TUESDAY...UPDATED 12Z... * WEDNESDAY NIGHT...VFR. * THURSDAY...VFR. SLIGHT CHANCE OF LIGHT RAIN...POSSIBLY MIXING WITH LIGHT SNOW. * FRIDAY...MVFR POSSIBLE. SLIGHT CHANCE OF LIGHT RAIN OR LIGHT SNOW. * SATURDAY...VFR. * SUNDAY...SLIGHT CHANCE OF LIGHT RAIN OR LIGHT SNOW. * MONDAY...SLIGHT CHANCE OF LIGHT SNOW. PAW && .MARINE... 235 AM CST AN AREA OF LOW PRESSURE CONTINUES TO SLOWLY MOVE EAST ACROSS SOUTHERN ONTARIO THIS MORNING. DRAPED SOUTH FROM THIS LOW AND SPANNING MUCH OF THE UPPER AND MIDDLE MISSISSIPPI VALLEY IS A COLD FRONT THAT WILL SLIDE ACROSS THE LAKE LATER THIS MORNING. AHEAD OF IT...THE 15 TO 25 KT WINDS WILL VEER TO THE WEST AND THEN TO THE NORTHWEST THROUGH THE EARLY AFTERNOON HOURS. THE STRONGEST SURGE OF COLD AIR IS NOT ANTICIPATED TO BE UNTIL THE LATER AFTERNOON HOURS FOR THE NORTHERN HALF OF THE LAKE...AND SHORTLY THEREAFTER FOR THE SOUTHERN HALF. IT IS WITH THIS SURGE THAT THE STRONGEST OF WINDS IS ANTICIPATED. HIGH END GALES ARE AGAIN LIKELY...BUT FOR THE ENTIRE SPAN OF THE LAKE WITH THIS EVENT AS OPPOSED TO THE STRONGEST WINDS REMAINING NORTH YESTERDAY. FORECAST SOUNDINGS ARE ALSO INDICATING THE POTENTIAL FOR LOW END STORM FORCE GUSTS. FEEL THAT THE MAJORITY OF THE WINDS WILL REMAIN BELOW STORM CRITERIA FOR THE OPEN WATERS AND WILL ONLY MENTION IN AN OCCASIONAL GROUP. THOUGHTS THEN TURN TO NEARSHORE BURNS HARBOR TO MICHIGAN CITY IN AND 744...AND POTENTIALLY 743 AND GALES. WITH THE STRONG NORTHWESTERLY WINDS EXPECTED...INCREASES THE CHANCES INTO THE EVENING HOURS AND OVERNIGHT. WILL ERR ON THE SIDE OF CAUTION FOR THE FRICTIONLESS MARINE LOCATIONS AND CANCEL THE SMALL CRAFT FOR THOSE LOCATIONS AND HOIST A GALE WARNING. CONDITIONS SET TO IMPROVE LATE TONIGHT AS RIDGING ACROSS THE SURFACE BUILDS...THOUGH PROLONGED STRONG SOUTHWESTERLY FLOW WILL SLOWLY RAMP UP THROUGH WEDNESDAY NIGHT...WITH FLOW PROGGED TO REMAIN BELOW GALE. SHEA && .LOT WATCHES/WARNINGS/ADVISORIES... IL...NONE. IN...NONE. LM...SMALL CRAFT ADVISORY...NEARSHORE GARY TO MICHIGAN CITY IN UNTIL NOON TUESDAY. GALE WARNING...LMZ080-LMZ261-LMZ362-LMZ364-LMZ366-LMZ563-LMZ565- LMZ567-LMZ669-LMZ671-LMZ673-LMZ675-LMZ744-LMZ745-LMZ777- LMZ779-LMZ868-LMZ870-LMZ872-LMZ874-LMZ876-LMZ878...NOON TUESDAY TO 3 AM WEDNESDAY. SMALL CRAFT ADVISORY...NEARSHORE WINTHROP HARBOR TO GARY IN UNTIL 6 PM WEDNESDAY. && $$
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
406 AM CST TUE DEC 27 2011 .DISCUSSION... 330 AM CST THE FORECAST CHALLENGES ARE FIRST ON THE IMMEDIATE SHORT TERM WITH PRECIPITATION GRADUALLY SHIFTING EASTWARD THIS MORNING...THEN THE LAKE EFFECT SHOWER POTENTIAL INTO NORTHWEST INDIANA THIS AFTERNOON AND EVENING. THE ACTIVE FLOW PATTERN ACROSS THE NORTHERN U.S. AND SOME UNDULATIONS IN THIS INTO THE NEW YEAR KEEP THE FORECAST INTERESTING LOOKING FORWARD. SHORT TERM...LOW PRESSURE IS DEVELOPING FAIRLY RAPIDLY UNDER STRONG JET SUPPORT ACROSS WESTERN KY. MOIST ADVECTION ALOFT AND ASSOCIATED ASCENT CONTINUES TO WORK ITS WAY ACROSS NORTHWEST INDIANA. AN ELONGATED NORTHERN STREAM WAVE PUSHING EAST ACROSS THE REGION HAS INTERACTED WITH THIS...HELPING TO PRODUCE BANDS OF MODERATE PRECIP AT TIMES WHERE CONVERGENCE OF ECHOES WAS OBSERVED /AND LIKELY IMPLYING FRONTOGENETIC FORCING/. WITHIN THESE...A FEW REPORTS OF SLEET WERE OBSERVED/REPORTED OR ESTIMATED THROUGH UNKNOWN PRECIP AUTOMATED REPORTS. STRONGER FORCING LIFTING NORTH ACROSS EASTERN IL/WESTERN IN HAS HELPED TO LEAD TO EVAPORATIONAL COOLING SUPPORTING SNOW...AND BENTON COUNTY REPORTED A COATING OF SNOW ON THEIR PAVEMENT AS OF 300 AM. EXPECT THE AREAS RECEIVING PRECIPITATION AT DAYBREAK TO BE MAINLY A WET SNOW...WITH A LITTLE LIGHT RAIN POSSIBLY JUST BEFORE IT ENDS ON THE WESTERN PERIPHERY. THE SHIELD OF PRECIP WILL TAKE A WHILE TO EVOLVE EAST OUT OF THE AREA BASED ON THE QG FORCING ON THE RUC AS WELL AS WATER VAPOR TRENDS WITH THE DRY SLOT NOSE LIFTING INTO CENTRAL IN HELPING TO KEEP MAINLY SNOW GOING IN THE SOUTHEAST FORECAST AREA THIS MORNING. MAXIMUM ACCUMULATIONS NEAR AN INCH TOWARDS FOWLER AND RENSSALEAR STILL LOOK VALID. IN THE FAR SOUTH AND SOUTHEAST CHICAGO METRO WHILE SNOW MAY STILL BE OCCURRING THROUGH 9 AM OR SO...NO ACCUMULATION IS EXPECTED. THIS AFTERNOON...STRONG NORTH TO NORTHWEST WINDS IN THE WAKE OF THE SYSTEM ESTABLISH THEMSELVES DOWN THE FETCH OF LAKE MI THIS AFTERNOON. CONVERGENCE STREAMLINES FROM THE 27.06 NAM FAVOR A CORRIDOR OF SATURATED CONVERGENCE CENTERED ON MICHIGAN CITY...WITH SOME FURTHER WEST TOWARDS PORTER COUNTY. LAKE INDUCED EQUILIBRIUM LEVELS ARE PROJECTED OVER 5000 FT ON THE NAM FOR LATE THIS AFTERNOON AND EVENING AND THUS HAVE INCREASED POPS IN THAT AREA FOR SOME SNOW SHOWERS. FROM THIS...ONLY AN ADDITIONAL DUSTING IS EXPECTED WITH POTENTIAL FOR MORE JUST EAST OF THE FORECAST AREA. TONIGHT THROUGH THURSDAY...THE TEMPERATURES TONIGHT WILL BE A BATTLE BETWEEN THE COLD AND DRY AIR ADVECTION THIS EVENING AND THEN MID TO HIGH CLOUDS ON THE INCREASE FROM THE WEST OVERNIGHT WITH AN APPROACHING SHORT WAVE. IN ADDITION...LINGERING STRATOCU IN THE CAA REGIME IS LIKELY EARLY THIS EVENING...AND THAT MAY RESIDE THROUGH A GOOD PART OF THE NIGHT IN EASTERN AREAS. MODEL SPREAD REFLECTS THIS...VARYING UP TO TEN DEGREES IN SOME LOCATIONS. CONFIDENCE IS THUS MINIMAL ON TONIGHTS LOWS...AND AM NEAR THE CENTER OF THE SPREAD AT THIS TIME. A STRONGER SHORT WAVE ARRIVES INTO SOUTHERN WI ON LATE WEDNESDAY NIGHT INTO THURSDAY MORNING. THIS IS A TRUE QUICK MOVING CLIPPER...WITH ITS BEST MOISTURE SUPPORT ALONG AND NORTH OF ITS PATH WHERE THE TIGHT MID- LEVEL THERMAL GRADIENT EXISTS. WHILE THERE IS FAIRLY STOUT 850-600 MB WAA AHEAD OF THIS FEATURE WED AFTERNOON AND EVENING...THE COLUMN LOOKS MUCH TOO DRY FOR PRECIP. SO ONLY HAVE POPS NEAR THE WI STATE LINE WITH THE ACTUAL LOW CENTER PASSAGE. THURSDAY NIGHT...WHAT HAD BEEN A DEEP SLOW-MOVING LOW IN THE LONGER RANGE FORECAST DAYS AGO HAS TRENDED TOWARDS A SHARP SOUTHEAST DIVING CLIPPER THAT STILL IS FAIRLY DEEP IN PRESSURE FOR CLIPPERS /~1002 MB/. THE PATH ON THE GFS AND EC FAVOR OUR AREA TO SEE SOME PRECIP...BUT EVEN A SLIGHT SHIFT NORTH OR SOUTH WOULD GREATLY REDUCE THEM AS IT IS A FAIRLY NARROW AXIS OF PRECIP WITH SUCH A STRUCTURE. INDEED THE 27.06 NAM IS A SOLUTION THAT IS FURTHER NORTH WITH LITTLE QPF. THE EC FOR TWO CONSECUTIVE RUNS HAS BEEN SLOWER THAN THE GFS...FAVORING OVERNIGHT THU AS OPPOSED TO THE EVE FOR INFLUENCE OVER OUR AREA. BOTH MODELS WOULD STILL SUPPORT SNOW CHANCES...BUT THE EC IS BETTER LOOKING FOR THAT WITH SLIGHTLY DEEPER HEIGHT FALLS AND GREATER MIXING RATIOS ON THE LIFTING SURFACES / 2.5-3 G/KG /. UNFORTUNATELY...THIS WAVE IS ONE OF MANY IN THE NORTHERN PACIFIC RIGHT NOW AND THUS NOT WELL SAMPLED. SO HAVE KEPT POPS ONLY AT A CHANCE BUT HAVE INCREASE VALUES. BEYOND...THE PROGRESSIVE PATTERN CONTINUES WITH AN IMMEDIATE INCREASE IN HEIGHTS AND A LOW-LEVEL THERMAL RIDGE INTO THE AREA. THE GFS...EC...AND GEM ALL BRING 850 MB TEMPERATURES TO ABOVE 8C ON SATURDAY. BIAS-CORRECTED FORECASTS FROM THESE MODELS BLENDED TOGETHER YIELDS HIGHS FROM THE UPPER 40S TO A STAGGERING MID 50S. WITH SUCH A QUICK TURNAROUND FROM COOL AIR ADVECTION BEHIND THE WAVE THURSDAY NIGHT/EARLY FRIDAY...WILL NOT BE GOING THAT HIGH. BUT HAVE BLENDED THE GOING FORECAST ALMOST 50 PERCENT WITH THESE. THIS AMPLIFIED PATTERN WHICH BRINGS IN THE WARMER REGIME IS AHEAD OF A DIGGING JET TO START THE NEW YEAR WHICH HAS BEEN HINTED AT IN SOLUTIONS FOR A WHILE. THIS WOULD AT LEAST BRING TEMPERATURES DOWN FOR EARLY NEXT WEEK...BUT CONFIDENCE IS LOW IN THIS AS WELL AS THE PRECIP CHANCES WITH THE SYSTEM EVOLVING ON THE JET UNDULATION. LOOKING INTO NEXT WEEK...DESPITE THE CHANCES FOR COOLER TEMPERATURES INITIALLY...THE 8 TO 14 DAY CPC OUTLOOK AND ESPECIALLY THE NAEFS MEMBERS FAVOR ABOVE NORMAL TEMPERATURES IN GENERAL. MTF && .AVIATION... //ORD AND MDW CONCERNS...UPDATED 10Z... * LIGHT RAIN...POSSIBLY MIXED WITH LIGHT SNOW...ENDING AROUND SUNRISE. * POSSIBILITY FOR FLURRIES THIS AFTERNOON. * IFR CIGS ASSOCIATED WITH PRECIPITATION IMPROVING TO MVFR BY MID MORNING. * WIND SHIFT TO NROTHWEST MID MORNING. WIND INCREASING AND BECOMING GUSTY BY LATE MORNING AND CONTINUING INTO THIS EVENING. PAW //DISCUSSION...UPDATED 06Z... LIGHT RAIN CONTINUES TO DEVELOP/SPREAD ACROSS NORTHERN IL LATE THIS EVENING WITH THE BACK EDGE EXTENDING FROM ROUGHLY MKE TO MLI. THIS WILL SLOWLY MOVE EAST ACROSS THE TERMINALS OVERNIGHT. LOW PRESSURE CURRENTLY NEAR MEMPHIS WILL LIFT NORTH ACROSS THE OHIO VALLEY THROUGH TUESDAY MORNING. AS IT DOES...ADDITIONAL PRECIP WILL SPREAD ACROSS EASTERN IL AND NORTHWEST INDIANA...LIKELY MIXING WITH THEN BECOMING ALL SNOW. WHEN AND WHERE THIS CHANGE OVER OCCURS IS THE CHALLENGE AND TRENDS STILL SUPPORT THE BULK OF THE PRECIP REMAINING JUST SOUTHEAST OF THE TERMINALS. THUS HAVE MADE NO SIGNIFICANT CHANGES WITH PREVAILING LIGHT RAIN THROUGH THE NIGHT WITH THE POTENTIAL TO MIX WITH SNOW OVERNIGHT. CIGS STILL VFR ACROSS THE AREA BUT MVFR CIGS DEVELOPING ACROSS CENTRAL IL AND AS LIGHT RAIN CONTINUES TO FALL...EXPECT CIGS TO GRADUALLY LOWER INTO MVFR. CONFIDENCE OF EXACTLY WHEN CIGS LOWER TO MVFR IS NOT PARTICULARLY HIGH...LIKELY IN THE 08Z-11Z TIME PERIOD...AND THIS WILL LIKELY NEED TWEAKING WITH OVERNIGHT UPDATES. IFR CIGS STILL POSSIBLE AND MOST LIKELY AFTER SUNRISE AS PRECIP ENDS...BUT AHEAD OF AN APPROACHING COLD FRONT. THIS FRONT SHOULD HELP LIFT ANY IFR CIGS BACK TO MVFR BY MID/LATE MORNING. ONCE WINDS SHIFT TO THE NORTHWEST...SPEEDS/GUSTS SHOULD STEADILY INCREASE AND WITH A PUSH OF COLDER AIR BY EARLY AFTERNOON...COULD BE SOME FLURRIES OR SNOW SHOWERS. SKIES BEGIN TO CLEAR BY LATE AFTERNOON/EARLY EVENING...AS WINDS ALSO BEGIN TO DIMINISH. CMS //ORD AND MDW CONFIDENCE...UPDATED 10Z... * MEDIUM CONFIDENCE IN TIMING OF PRECIPITATION ENDING THIS MORNING. * MEDIUM CONFIDENCE IN FLURRIES THIS AFTERNOON. * MEDIUM CONFIDENCE IN TIMING OF IFR CIG IMPROVEMENT. * HIGH CONFIDENCE IN WIND TREND. PAW //OUTLOOK FOR ORD/MDW FOR 12Z WEDNESDAY-12Z MONDAY...UPDATED 00Z... * WEDNESDAY...VFR. * THURSDAY...VFR. SLIGHT CHANCE OF LIGHT RAIN...POSSIBLY MIXING WITH LIGHT SNOW. * FRIDAY...MVFR POSSIBLE. SLIGHT CHANCE OF LIGHT RAIN OR LIGHT SNOW. * SATURDAY...VFR. * SUNDAY..SLIGHT CHANCE OF LIGHT RAIN OR LIGHT SNOW. CMS && .MARINE... 235 AM CST AN AREA OF LOW PRESSURE CONTINUES TO SLOWLY MOVE EAST ACROSS SOUTHERN ONTARIO THIS MORNING. DRAPED SOUTH FROM THIS LOW AND SPANNING MUCH OF THE UPPER AND MIDDLE MISSISSIPPI VALLEY IS A COLD FRONT THAT WILL SLIDE ACROSS THE LAKE LATER THIS MORNING. AHEAD OF IT...THE 15 TO 25 KT WINDS WILL VEER TO THE WEST AND THEN TO THE NORTHWEST THROUGH THE EARLY AFTERNOON HOURS. THE STRONGEST SURGE OF COLD AIR IS NOT ANTICIPATED TO BE UNTIL THE LATER AFTERNOON HOURS FOR THE NORTHERN HALF OF THE LAKE...AND SHORTLY THEREAFTER FOR THE SOUTHERN HALF. IT IS WITH THIS SURGE THAT THE STRONGEST OF WINDS IS ANTICIPATED. HIGH END GALES ARE AGAIN LIKELY...BUT FOR THE ENTIRE SPAN OF THE LAKE WITH THIS EVENT AS OPPOSED TO THE STRONGEST WINDS REMAINING NORTH YESTERDAY. FORECAST SOUNDINGS ARE ALSO INDICATING THE POTENTIAL FOR LOW END STORM FORCE GUSTS. FEEL THAT THE MAJORITY OF THE WINDS WILL REMAIN BELOW STORM CRITERIA FOR THE OPEN WATERS AND WILL ONLY MENTION IN AN OCCASIONAL GROUP. THOUGHTS THEN TURN TO NEARSHORE BURNS HARBOR TO MICHIGAN CITY IN AND 744...AND POTENTIALLY 743 AND GALES. WITH THE STRONG NORTHWESTERLY WINDS EXPECTED...INCREASES THE CHANCES INTO THE EVENING HOURS AND OVERNIGHT. WILL ERR ON THE SIDE OF CAUTION FOR THE FRICTIONLESS MARINE LOCATIONS AND CANCEL THE SMALL CRAFT FOR THOSE LOCATIONS AND HOIST A GALE WARNING. CONDITIONS SET TO IMPROVE LATE TONIGHT AS RIDGING ACROSS THE SURFACE BUILDS...THOUGH PROLONGED STRONG SOUTHWESTERLY FLOW WILL SLOWLY RAMP UP THROUGH WEDNESDAY NIGHT...WITH FLOW PROGGED TO REMAIN BELOW GALE. SHEA && .LOT WATCHES/WARNINGS/ADVISORIES... IL...NONE. IN...NONE. LM...GALE WARNING...LMZ080-LMZ261-LMZ362-LMZ364-LMZ366-LMZ563-LMZ565- LMZ567-LMZ669-LMZ671-LMZ673-LMZ675-LMZ777-LMZ779-LMZ868- LMZ870-LMZ872-LMZ874-LMZ876-LMZ878...NOON TUESDAY TO 3 AM WEDNESDAY. SMALL CRAFT ADVISORY...NEARSHORE WATERS UNTIL 6 PM WEDNESDAY. && $$
AREA FORECAST DISCUSSION
NWS GOODLAND KS
413 AM MST TUE DEC 27 2011 .SYNOPSIS... CURRENT SATELLITE IMAGERY AND RUC UPPER AIR ANALYSIS SHOW A HIGH PRESSURE OVER THE SOUTHWEST CONUS...WITH A SHORT WAVE TROUGH AND MID LEVEL MOISTURE MOVING AROUND THE NORTHERN PERIPHERY OF THE HIGH ALONG THE US/CANADIAN BORDER. OVER THE CENTRAL PLAINS A SHORT WAVE TROUGH IN THE NORTHWEST FLOW WAS PRODUCING A FEW CLOUDS. CLOSER TO HOME A SURFACE HIGH PRESSURE WAS BUILDING INTO THE TRI-STATE AREA. LATEST REPORTS OF SNOW DEPTH SHOW 2 TO 10 INCHES STILL ON THE GROUND FOR AREAS OF CENTRAL AND SOUTHWEST KANSAS...SO AM EXPECTING THIS TO HAVE A COOLING EFFECT ON TEMPERATURES THROUGH THE PERIOD. JTL && .SHORT TERM (TODAY-THURSDAY)... 228 AM MST TUE DEC 27 2011 TEMPERATURES WILL BE THE MAIN CONCERN FOR THIS PERIOD. SURFACE HIGH PRESSURE WILL MOVE ACROSS THE TRI-STATE AREA TODAY...PRECEDING A SURFACE AND UPPER LEVEL TROUGH THAT WILL MOVE THROUGH DURING THE EVENING HOURS. MODELS HAVE REDUCED THE AMOUNT OF MOISTURE AND LIFT WITH THE TROUGH PASSAGE...SO WILL FOLLOW PREVIOUS SHIFT AND KEEP OUT ANY MENTION OF PRECIPITATION. HIGH TEMPERATURES A BIT TRICKY DUE TO THE COMBINED EFFECTS OF CLOUD COVER AND SOUTHERLY WINDS BRINGING IN COOLER AIR FROM THE SNOW FIELD...BUT OVERALL TEMPERATURES TODAY WILL BE COOLER THAN YESTERDAY. LOWS TONIGHT WILL BE A FEW DEGREES WARMER THAN LAST NIGHT. WEDNESDAY MINOR RIPPLES WILL MOVE THROUGH THE UPPER LEVEL FLOW OVER THE AREA...PRODUCING A FEW CLOUDS AT BEST. WITH WESTERLY WINDS BRINGING IN WARMER AIR...TEMPERATURES WILL BE WARMER THAN TUESDAY. THURSDAY A MINOR SHORT WAVE TROUGH AND SOME MOISTURE MOVE THROUGH THE UPPER LEVEL FLOW OVER THE AREA. THIS TROUGH WILL HAVE MORE LIFT WITH IT...BUT WILL HAVE THE BEST LIFT BELOW THE MOISTURE. AS SUCH WILL LEAVE OUT A MENTION OF ANY PRECIPITATION AS THE TROUGH MOVES THROUGH. AT THE SURFACE WINDS WILL BECOME NORTHWEST BEHIND THE TROUGH AND STRENGTHEN SOME...WITH THE STRONGER WINDS OVER THE NEBRASKA COUNTIES. TEMPERATURES WILL CONTINUE THE WARMING TREND. 850MB TEMPERATURES WARM TO NEAR 10C DURING THE DAY...SO WENT WITH THE WARMER GUIDANCE SINCE 850MB TEMPERATURES OF 3C YESTERDAY AND NORTHWEST WINDS PRODUCED HIGHS AROUND 50 DEGREES...SO HIGHS AROUND 60 ARE NOT OUT OF THE QUESTION. JTL .LONG TERM (FRIDAY-MONDAY)... 228 AM MST TUE DEC 27 2011 LONG RANGE MODELS CONTINUE TO SHOW WEAK SHORT WAVE TROUGHS MOVING ACROSS THE HIGH PLAINS IN PSEUDO ZONAL FLOW THROUGH THE WEEKEND. THE STRONGEST WAVE IS DUE SATURDAY AFTERNOON OR SATURDAY NIGHT DEPENDING ON MODEL PREFERENCE...BUT MOISTURE APPEARS LIMITED REGARDLESS SO WILL KEEP FORECASTS DRY. WARM AIR ADVECTION AND ABOVE NORMAL 500 MB HEIGHTS SUPPORT DECENT WARM/UP BETWEEN THE SHORT WAVES...ESPECIALLY FRIDAY WHEN 850 MB TEMPERATURES ARE PROGGED TO REACH BETWEEN 12-14 DEGREES CELSIUS. AGREE WITH SURROUNDING OFFICES TO INCREASE MAXIMUM TEMPERATURE FORECASTS THAT DAY. EVEN WITH WARM AIR ADVECTION...TEMPERATURES SOUTH OF INTERSTATE 70 WILL BE DEPENDENT ON THE AMOUNT OF SNOW PACK MELTING THAT OCCURS BETWEEN NOW AND FRIDAY. EXPECT ENOUGH MELTING TO ALLOW TEMPERATURES TO FINALLY REACH INTO THE 50S THERE BY FRIDAY. && .AVIATION... 413 AM MST TUE DEC 27 2011 VFR CONDITIONS WILL CONTINUE THROUGH THE FORECAST PERIOD AT KGLD/KMCK. SURFACE WINDS AT 10-15 KNOTS WILL GRADUALLY BECOME SOUTHWEST TODAY BEFORE RETURNING TO THE NORTHWEST AFTER 00Z. && .GLD WATCHES/WARNINGS/ADVISORIES... KS...NONE. NE...NONE. CO...NONE. && $$
AREA FORECAST DISCUSSION...UPDATED
NWS NASHVILLE TN
614 AM CST TUE DEC 27 2011 .UPDATE... MAIN AREA OF MODERATE RAINFALL HAS MOVED NORTHEAST OF MID STATE THIS MORNING. SHORT RANGE/HRRR MODELS ALSO SHOWING THAT SHWRS WILL CONTINUE TO OCCUR...NOT STEADILY...BUT AT IRREGULAR INTERVALS...AS SFC/UPPER LEVEL TROUGH MOVES TO THE NE THRU THE MORNING HRS. THUS... WILL UPDATE THE SUITE OF FORECAST PRODUCTS TO REFLECT INTERMITTENT SHWRS ALL AREAS THRU THE MORNING HRS. && .PREV DISCUSSION.../ISSUED 523 AM CST TUE DEC 27 2011/ UPDATE...FOR AVIATION. AVIATION... 12Z TAFS...LOW PRESSURE NEAR CKV WILL DEEPEN AS IT MOVES NORTHEAST ACROSS KY TODAY. INCREASING PRESSURE GRADIENT WILL CAUSE GUSTY WINDS TO 25KT OR SO TO DEVELOP...FROM THE SW THIS MORNING...THEN BECOMING WNW. SCATTERED SHOWERS WILL OCCUR MAINLY THIS MORNING WITH SOME MVFR VSBYS. CIGS WILL BE MAINLY IFR THROUGH THE MORNING. BNA WILL IMPROVE TO MVFR IN THE AFTERNOON AND VFR TONIGHT. CSV WILL HOVER FROM IFR TO MVFR THROUGH THE PERIOD. 13 PREV DISCUSSION... /ISSUED 333 AM CST TUE DEC 27 2011/ DISCUSSION... FORECAST REASONING WILL LEAN TOWARD A CONSENSUS MODEL SOLUTION COMPROMISE FOR THE FORECAST PERIOD UNLESS OTHERWISE NOTED. MAIN FORECAST QUANDARIES...ACTUAL TIMING OF RAINFALL ENDING W TO E AND STRENGTH OF WINDS TODAY...POSSIBLE RAIN/SNOW MIX PLATEAU THIS EVENING...TEMPS...AND OVERALL FORECAST EARLY NEXT WEEK. AS FOR TODAY...AS OF 09Z...WIDE SWATH OF LIGHT TO MODERATE SHWRS MOVING GENERALLY S TO N ACROSS MID STATE ACROSS LOCATIONS GENERALLY ALONG AND E OF I-65. SOME BREAKS IN RAINFALL NOTED W OF THIS AREA... BUT SHWRS DEVELOPING IN VICINITY OF UPPER LEVEL LOW ACROSS W TN AND ERN AK. ALL OF THIS AS SFC LOW CONTINUES TO MOVE ACROSS W TN...WITH UPPER LEVEL TROUGH BEGINNING TO MOVE INTO FAR WRN PORTIONS OF THE STATE. WILL BE MAKING FINAL DECISION AT PRESS TIME...BUT AM LEANING TOWARD DEF SHWRS GENERALLY E OF I-65 TO NUMEROUS SHWRS W...TRANSITIONING TO NUMEROUS TO SCATTERED LIGHT SHWRS ALL LOCATIONS EXPECT THOSE CLOSE TO AND ACROSS THE CUMBERLAND PLATEAU REGION DURING THE LATER MORNING HRS. THIS AFTERNOON THE MID STATE SHOULD EXPERIENCE AREAS ACROSS WRN MIDDLE TN FINALLY BECOME DRY NEAR AND JUST EAST OF THE TN RIVER VALLEY REGION...WITH ISO/SCT LIGHT SHWRS ACROSS THE REMAINDER OF THE MID STATE DURING THE AFTERNOON HRS. THIS REASONING BASED ON THE FACT THAT THE SFC LOW AND UPPER LEVEL TROUGH WILL CONTINUE TO MOVE NEWD OVER TIME WITH CLDY SKIES ACROSS MOST LOCATIONS THRU THE AFTERNOON HRS. HRRR MODEL HINTING AT THE POTENTIAL FOR A RAIN/SNOW MIX ACROSS FAR NW PORTIONS OF THE MID STATE BY THE EARLY AFTERNOON HRS...BUT WITH TEMPS EXPECTED TO REMAIN VERY CLOSE TO CURRENT TEMPS IN THE LOWER 40S THRU THE AFTERNOON HRS...WILL NOT MENTION IN THE SUITE OF FORECAST PRODUCTS AS OF THIS TIME. DO NOT EXPECT OTHER LOCATIONS ACROSS THE MID STATE TO DEVIATE MUCH FROM CURRENT TEMPS BEING EXPERIENCED. AS THIS SYSTEM MOVES NEWD...EXPECT SOME MIXING DOWN OF 30 TO 40 MPH 925MB WINDS TO THE SFC DURING THE AFTERNOON HRS. DO NOT EXPECT ANY LOCATION ACROSS THE MID STATE TO REACH WIND ADVISORY CRITERIA AS OF THIS TIME...BUT WOULD NOT BE SURPRISED THAT SOME LOCATIONS EXPERIENCE GUSTS OF 25 TO 30 MPH LATER THIS AFTERNOON. AS FOR TONIGHT...THERE MIGHT BE A SLIGHT CHANCE OF A RAIN/SNOW MIXTURE ACROSS NRN PORTIONS OF THE CUMBERLAND PLATEAU DURING THE EARLY EVENING HRS AS MOISTURE ASSOCIATED WITH UPPER LEVEL TROUGH MOVES ACROSS THIS PART OF THE MID STATE AND WITH TEMPS EXPECTED TO FALL INTO THE UPPER TO MID 30S. HOWEVER...AS OF THIS TIME...NO ACCUMULATION IS EXPECTED. OTHERWISE...LOOK FOR A SLOW DECREASE IN CLOUDINESS W TO E ACROSS THE MID STATE...WITH DRY CONDITIONS...AND LOWS NEAR NORMAL VALUES FOR THIS TIME OF YEAR...AROUND 30...UPPER 20S PLATEAU. AS FOR WED...A WEAK SHORTWAVE PASSAGE IS EXPECTED ACROSS THE SRN OHIO VALLEY AND PORTIONS OF KY DURING THE AFTERNOON HRS...WHICH MIGHT BRING SOME ADDITIONAL CLOUDINESS TO LOCATIONS APPROACHING THE TN/KY BORDER. HOWEVER...AT THIS TIME...WILL GO WITH PTCDLY SKIES ACROSS THE ENTIRE MID STATE...WITH AFTERNOON HIGH TEMPS GETTING BACK CLOSE TO CLIMATOLOGICAL NORMS...WITH HIGHS IN THE MID 40S N TO UPPER 40S S...LOW 40S PLATEAU. AS FOR WED NIGHT...SKIES SHOULD EVENTUALLY BECOME MOCLR BY LATE WED NIGHT...WITH LOWS AGAIN IN THE LOWER 30S...UPPER 20S PLATEAU. AS FOR THU...AS HIGH SHIFTS EWD...AND MORE OF A SLY SFC FLOW DEVELOPS ACROSS THE MID STATE...HIGHS SHOULD WARM UP INTO THE LOWER TO MID 50S... WITH PTCLDY SKIES AND DRY CONDITIONS. AS FOR THE REST OF THE FORECAST PERIOD...WILL KEEP IT DRY THRU NEW YEARS DAY...WHEN THE NEXT CHANCE OF RAINFALL ACROSS THE MID STATE WILL OCCUR AS ANOTHER COLD FRONT IS EXPECTED TO MOVE ACROSS THE MID STATE. INTO THE FIRST HALF OF NEXT WEEK THOUGH...SIGNIFICANT MODEL DIFFERENCES ARE OCCURRING. THE GFS BEING THE DRIER AND WARMER SOLUTION AND THE EURO BEING THE COLDER AND WETTER SOLUTION. AM GOING TO PLAY IT MIDDLE OF THE ROAD HERE...AND GO WITH A DRY FORECAST...A LEAN MORE TOWARD THE GFS...AS I AM A LITTLE WEARY OF THE VERY PROGRESSIVE AND DEEP UPPER LEVEL LOW AND TROUGH SOLUTION THAT THE EURO IS ADVERTISING ACROSS THE MID SOUTH NEXT TUE INTO WED. THRU THIS PERIOD...AFTERNOON HIGH TEMPS WILL MAINLY BE IN THE 50S...WITH OVERNIGHT LOWS...EXPECT FOR SAT NIGHT WHICH WILL BE IN THE MID 40S...MAINLY IN THE 30S. 31 && .OHX WATCHES/WARNINGS/ADVISORIES... NONE. && $$ 31
AREA FORECAST DISCUSSION
NWS NASHVILLE TN
523 AM CST TUE DEC 27 2011 .UPDATE...FOR AVIATION. && .AVIATION... 12Z TAFS...LOW PRESSURE NEAR CKV WILL DEEPEN AS IT MOVES NORTHEAST ACROSS KY TODAY. INCREASING PRESSURE GRADIENT WILL CAUSE GUSTY WINDS TO 25KT OR SO TO DEVELOP...FROM THE SW THIS MORNING...THEN BECOMING WNW. SCATTERED SHOWERS WILL OCCUR MAINLY THIS MORNING WITH SOME MVFR VSBYS. CIGS WILL BE MAINLY IFR THROUGH THE MORNING. BNA WILL IMPROVE TO MVFR IN THE AFTERNOON AND VFR TONIGHT. CSV WILL HOVER FROM IFR TO MVFR THROUGH THE PERIOD. 13 && .PREV DISCUSSION... /ISSUED 333 AM CST TUE DEC 27 2011/ DISCUSSION... FORECAST REASONING WILL LEAN TOWARD A CONSENSUS MODEL SOLUTION COMPROMISE FOR THE FORECAST PERIOD UNLESS OTHERWISE NOTED. MAIN FORECAST QUANDARIES...ACTUAL TIMING OF RAINFALL ENDING W TO E AND STRENGTH OF WINDS TODAY...POSSIBLE RAIN/SNOW MIX PLATEAU THIS EVENING...TEMPS...AND OVERALL FORECAST EARLY NEXT WEEK. AS FOR TODAY...AS OF 09Z...WIDE SWATH OF LIGHT TO MODERATE SHWRS MOVING GENERALLY S TO N ACROSS MID STATE ACROSS LOCATIONS GENERALLY ALONG AND E OF I-65. SOME BREAKS IN RAINFALL NOTED W OF THIS AREA... BUT SHWRS DEVELOPING IN VICINITY OF UPPER LEVEL LOW ACROSS W TN AND ERN AK. ALL OF THIS AS SFC LOW CONTINUES TO MOVE ACROSS W TN...WITH UPPER LEVEL TROUGH BEGINNING TO MOVE INTO FAR WRN PORTIONS OF THE STATE. WILL BE MAKING FINAL DECISION AT PRESS TIME...BUT AM LEANING TOWARD DEF SHWRS GENERALLY E OF I-65 TO NUMEROUS SHWRS W...TRANSITIONING TO NUMEROUS TO SCATTERED LIGHT SHWRS ALL LOCATIONS EXPECT THOSE CLOSE TO AND ACROSS THE CUMBERLAND PLATEAU REGION DURING THE LATER MORNING HRS. THIS AFTERNOON THE MID STATE SHOULD EXPERIENCE AREAS ACROSS WRN MIDDLE TN FINALLY BECOME DRY NEAR AND JUST EAST OF THE TN RIVER VALLEY REGION...WITH ISO/SCT LIGHT SHWRS ACROSS THE REMAINDER OF THE MID STATE DURING THE AFTERNOON HRS. THIS REASONING BASED ON THE FACT THAT THE SFC LOW AND UPPER LEVEL TROUGH WILL CONTINUE TO MOVE NEWD OVER TIME WITH CLDY SKIES ACROSS MOST LOCATIONS THRU THE AFTERNOON HRS. HRRR MODEL HINTING AT THE POTENTIAL FOR A RAIN/SNOW MIX ACROSS FAR NW PORTIONS OF THE MID STATE BY THE EARLY AFTERNOON HRS...BUT WITH TEMPS EXPECTED TO REMAIN VERY CLOSE TO CURRENT TEMPS IN THE LOWER 40S THRU THE AFTERNOON HRS...WILL NOT MENTION IN THE SUITE OF FORECAST PRODUCTS AS OF THIS TIME. DO NOT EXPECT OTHER LOCATIONS ACROSS THE MID STATE TO DEVIATE MUCH FROM CURRENT TEMPS BEING EXPERIENCED. AS THIS SYSTEM MOVES NEWD...EXPECT SOME MIXING DOWN OF 30 TO 40 MPH 925MB WINDS TO THE SFC DURING THE AFTERNOON HRS. DO NOT EXPECT ANY LOCATION ACROSS THE MID STATE TO REACH WIND ADVISORY CRITERIA AS OF THIS TIME...BUT WOULD NOT BE SURPRISED THAT SOME LOCATIONS EXPERIENCE GUSTS OF 25 TO 30 MPH LATER THIS AFTERNOON. AS FOR TONIGHT...THERE MIGHT BE A SLIGHT CHANCE OF A RAIN/SNOW MIXTURE ACROSS NRN PORTIONS OF THE CUMBERLAND PLATEAU DURING THE EARLY EVENING HRS AS MOISTURE ASSOCIATED WITH UPPER LEVEL TROUGH MOVES ACROSS THIS PART OF THE MID STATE AND WITH TEMPS EXPECTED TO FALL INTO THE UPPER TO MID 30S. HOWEVER...AS OF THIS TIME...NO ACCUMULATION IS EXPECTED. OTHERWISE...LOOK FOR A SLOW DECREASE IN CLOUDINESS W TO E ACROSS THE MID STATE...WITH DRY CONDITIONS...AND LOWS NEAR NORMAL VALUES FOR THIS TIME OF YEAR...AROUND 30...UPPER 20S PLATEAU. AS FOR WED...A WEAK SHORTWAVE PASSAGE IS EXPECTED ACROSS THE SRN OHIO VALLEY AND PORTIONS OF KY DURING THE AFTERNOON HRS...WHICH MIGHT BRING SOME ADDITIONAL CLOUDINESS TO LOCATIONS APPROACHING THE TN/KY BORDER. HOWEVER...AT THIS TIME...WILL GO WITH PTCDLY SKIES ACROSS THE ENTIRE MID STATE...WITH AFTERNOON HIGH TEMPS GETTING BACK CLOSE TO CLIMATOLOGICAL NORMS...WITH HIGHS IN THE MID 40S N TO UPPER 40S S...LOW 40S PLATEAU. AS FOR WED NIGHT...SKIES SHOULD EVENTUALLY BECOME MOCLR BY LATE WED NIGHT...WITH LOWS AGAIN IN THE LOWER 30S...UPPER 20S PLATEAU. AS FOR THU...AS HIGH SHIFTS EWD...AND MORE OF A SLY SFC FLOW DEVELOPS ACROSS THE MID STATE...HIGHS SHOULD WARM UP INTO THE LOWER TO MID 50S... WITH PTCLDY SKIES AND DRY CONDITIONS. AS FOR THE REST OF THE FORECAST PERIOD...WILL KEEP IT DRY THRU NEW YEARS DAY...WHEN THE NEXT CHANCE OF RAINFALL ACROSS THE MID STATE WILL OCCUR AS ANOTHER COLD FRONT IS EXPECTED TO MOVE ACROSS THE MID STATE. INTO THE FIRST HALF OF NEXT WEEK THOUGH...SIGNIFICANT MODEL DIFFERENCES ARE OCCURRING. THE GFS BEING THE DRIER AND WARMER SOLUTION AND THE EURO BEING THE COLDER AND WETTER SOLUTION. AM GOING TO PLAY IT MIDDLE OF THE ROAD HERE...AND GO WITH A DRY FORECAST...A LEAN MORE TOWARD THE GFS...AS I AM A LITTLE WEARY OF THE VERY PROGRESSIVE AND DEEP UPPER LEVEL LOW AND TROUGH SOLUTION THAT THE EURO IS ADVERTISING ACROSS THE MID SOUTH NEXT TUE INTO WED. THRU THIS PERIOD...AFTERNOON HIGH TEMPS WILL MAINLY BE IN THE 50S...WITH OVERNIGHT LOWS...EXPECT FOR SAT NIGHT WHICH WILL BE IN THE MID 40S...MAINLY IN THE 30S. 31 && .OHX WATCHES/WARNINGS/ADVISORIES...NONE. && $$
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
521 AM CST TUE DEC 27 2011 .SHORT TERM...TODAY THROUGH THURSDAY NIGHT 305 AM CST TUE DEC 27 2011 MAIN FORECAST CONCERN IS ON LOW PRECIPITATION CHANCES THROUGHOUT THE SHORT TERM PERIOD. CURRENTLY AS OF 08Z...WATER VAPOR LOOP AND RUC 500MB HEIGHT ANALYSIS SHOWED A SHORTWAVE TROUGH OVER BRITISH COLUMBIA...WEAK RIDGING OVER THE SOUTHWEST U.S. INTO ALBERTA AND SASKATCHEWAN...AN UPPER TROUGH OVER MINNESOTA AND AN UPPER LOW OVER NORTHERN MISSISSIPPI. THE UPPER TROUGH IS GRADUALLY BRINGING COLDER AIR INTO THE UPPER MISSISSIPPI RIVER VALLEY REGION...NOTED BY 850MB TEMPS THAT FELL BETWEEN 12Z YESTERDAY AND 00Z TODAY FROM 4C TO 1C AT MPX...AND 6 TO -2C AT BIS. MORE COLD AIR LURKS FARTHER UPSTREAM WITH -12C REPORTED AT THE PAS MANITOBA. MID TO UPPER LEVEL DYNAMIC LIFT WITH THE TROUGH IS FAIRLY WEAK AND MOSTLY OFF TO THE EAST OVER LAKE MICHIGAN...PER QG APPEARANCE FROM THE RUC/ECMWF. THIS LIFT IS WHAT HELPED PRODUCE THE RAIN/SLEET/SNOW LAST EVENING. BIGGER ISSUE WITH THE UPPER TROUGH IS ACTUALLY THE SUBSIDENCE AND THE COLD ADVECTION...WHICH IS HELPING TO PRODUCE 15-20 KT SURFACE SUSTAINED WINDS AND GUSTS TO 30 KT ACROSS MUCH OF MINNESOTA. THESE ARE OCCURRING IN THE WAKE OF TWO COLD FRONTS: THE FIRST SITUATED NORTH-SOUTH OVER CENTRAL WISCONSIN AND THE SECOND ALIGNED WEST EAST FROM ABERDEEN SOUTH DAKOTA INTO UPPER MICHIGAN. A LARGE AMOUNT OF STRATUS EXISTS BEHIND THESE FRONTS...WITH THE LOWEST CEILINGS BEHIND THE SECONDARY FRONT WHERE A GREATER SURGE OF COLD AIR ADVECTION IS HELPING TO UNDERCUT LOW LEVEL MOISTURE. A FEW FLURRIES ALSO OCCURRING FROM THE STRATUS. TODAY AND TONIGHT...MODELS PROG THE UPPER TROUGH OVER MINNESOTA TO MOVE RAPIDLY TO THE EAST...IN RESPONSE TO FAST FLOW COMING OFF THE PACIFIC. BY MIDNIGHT TONIGHT...THE UPSTREAM WEAK RIDGING SHOULD HAVE MOVED INTO THE FORECAST AREA. THIS SITUATION MEANS THAT THE CURRENT STRATUS AND STRONGER WINDS MOVING INTO THE FORECAST AREA FROM MINNESOTA WILL NOT STAY AROUND LONG. IN FACT...GOOD MODEL AGREEMENT EXISTS THAT SKIES SHOULD CLEAR OUT ACROSS MINNESOTA AND IOWA BETWEEN 18-21Z TODAY. ON THE OTHER HAND...OVER WISCONSIN...THERE ARE SUGGESTIONS BY THE 27.00Z NAM/27.03Z RUC THAT THE STRATUS MAY LINGER THROUGH THE EVENING BEFORE DISSIPATING AFTER MIDNIGHT (PER 925MB RH DATA). THIS CERTAINLY SEEMS PLAUSIBLE...SINCE STRATUS TYPICALLY LINGERS LONGER THAN ONE WOULD EXPECT THIS TIME OF YEAR. ALSO...THERE SHOULD BE A GOOD TRANSPORT OF MOISTURE OFF LAKE SUPERIOR GIVEN COLDER AIR FLOWING SOUTH. THEREFORE...HAVE RAISED SKY COVER VALUES OVER WISCONSIN FOR THIS EVENING. REGARDING PRECIP CHANCES WITH THE STRATUS...ANY LIFT IS VERY WEAK...ASSOCIATED WITH LOW LEVEL FRONTOGENESIS. GIVEN OVERALL LACK OF PRECIPITATION RIGHT NOW ON RADAR...ONLY WENT WITH FLURRIES THIS MORNING. DRYING TREND SHOWING UP NOW IN THE HRRR RUNS WOULD AGREE WITH THIS AS WELL. AFTER THAT... SUBSIDENCE TAKING HOLD SHOULD SHUT OFF ANY PRECIPITATION ACTION. LOOKING AHEAD TO AFTER MIDNIGHT TONIGHT...SHORTWAVE TROUGH OVER BRITISH COLUMBIA ALONG WITH A WEAKER SHORTWAVE CURRENTLY SEEN OVER IDAHO ARE FORECAST TO BEGIN TO DROP DOWN INTO MINNESOTA AROUND 12Z TUESDAY. WARM ADVECTION AHEAD OF THESE SHOULD RESULT IN A MID CLOUD DECK OF STRATUS...WHILE ANY PRECIPITATION STAYS NORTHWEST OF THE FORECAST AREA. REGARDING TEMPERATURES...WITH COLD ADVECTION OCCURRING TODAY NOTED BY 850MB TEMPS FALLING TO -5 TO -8C BY 18Z...ANTICIPATING GENERALLY STEADY OR FALLING TEMPERATURES. TONIGHT IS A LITTLE TRICKY WITH STRATUS OVER WISCONSIN AND THEN CLOUDS COMING IN AFTER MIDNIGHT EVERYWHERE. FOR NOW HAVE FOLLOWED A BLEND OF GUIDANCE FOR LOWS. WEDNESDAY AND WEDNESDAY NIGHT...SHORTWAVE OVER MINNESOTA AT 12Z WEDNESDAY IS FORECAST TO SHIFT EAST FAIRLY QUICKLY...REACHING LOWER MICHIGAN BY 00Z THURSDAY. BIGGEST CONCERN WITH THIS SHORTWAVE IS POTENTIAL FOR SOME WARM ADVECTION LIGHT SNOW SKIRTING TAYLOR AND CLARK COUNTIES. THE 00Z NAM/26.21Z SREF SUGGEST THIS IS POSSIBLE... WHEREAS THE 27.00Z GFS/26.12Z ECMWF ARE DRY. GIVEN THE WAY RECENT SYSTEMS HAVE GONE...WITH LIGHT PRECIPITATION HAPPENING DESPITE PRESENCE OF LOW LEVEL DRY AIR...FEEL COMPELLED TO AT LEAST PLACE A 20 PERCENT CHANCE IN TAYLOR AND CLARK COUNTIES. ELSEWHERE...A DECREASING CLOUD TREND SHOULD OCCUR WITH TEMPERATURES CLIMBING INTO THE 30S. COULD SEE READINGS PUSH 40 IN FAR WESTERN AREAS. FOR WEDNESDAY NIGHT...ATTENTION RE-FOCUSES TO THE NORTHWEST WHERE MODELS SHOW A DECENT SHORTWAVE MOVING THROUGH A FAST WEST-NORTHWEST UPPER LEVEL FLOW. AT 00Z...MODELS SUGGEST IT IS EITHER OVER EASTERN MONTANA OR SOUTHEAST SASKATCHEWAN...THEN IT MARCHES SOUTHEAST INTO THE FORECAST AREA AROUND 12Z THURSDAY. AS FAR AS WHERE IN THE FORECAST AREA...THIS VARIES GREATLY...SO FOR NOW HAVE TAKEN A BLEND APPROACH GIVEN THE FAST FLOW. AS THE SHORTWAVE APPROACHES...SHOULD SEE MID AND HIGH CLOUDS DEVELOP IN RESPONSE TO WARM ADVECTION AND DPVA FORCING. LIGHT PRECIPITATION COULD EVEN START BREAKING OUT IN NORTHWESTERN PORTIONS OF THE AREA IN THE EVENING. AFTER MIDNIGHT... ANTICIPATING SOME LIGHT PRECIPITATION EVERYWHERE. PRECIPITATION CHANCES REMAIN IN THE 20 TO 30 RANGE...HOWEVER...DUE TO THE LARGE SPREAD IN TRACK OF THE SHORTWAVE. ENVISION CHANCES NEEDING A BUMP UP IN LATER FORECASTS...BUT WHERE IS THE QUESTION. WITH THE CLOUDS MOVING IN...NOT ANTICIPATING AS MUCH OF A TEMPERATURE FALL AS TONIGHT. GENERALLY FOLLOWED A BLEND OF GUIDANCE FOR LOWS. THURSDAY AND THURSDAY NIGHT...SIMILAR TO THE PAST FEW DAYS...THE PARADE OF SHORTWAVES FROM THE PACIFIC CONTINUE TO COME THROUGH THE FAST FLOW. SHORTWAVE THAT IS NEAR/OVER THE AREA AT 12Z THURSDAY IS PROGGED TO REACH LOWER MICHIGAN BY 00Z...WHILE ANOTHER SHORTWAVE MOVES INTO THE DAKOTAS. SHOULD SEE THE PRECIPITATION DIMINISH FOR A TIME THURSDAY...ESPECIALLY IN THE AFTERNOON NORTH OF I-90 AS THAT AREA GETS INTO THE SUBSIDENCE BEHIND THE MORNING SHORTWAVE. DURING THE AFTERNOON...PRECIPITATION IS POSSIBLE SOUTH OF I-90 AS WARM ADVECTION OCCURS DOWNSTREAM OF THE SHORTWAVE ENTERING THE DAKOTAS. WITH UNCERTAINTY ON THE PLACEMENT OF THE SHORTWAVE NEAR/OVER THE AREA AT 12Z THURSDAY...ALONG WITH SUGGESTIONS OF LOW LEVEL DRY AIR TO OVERCOME IN SOUNDINGS...HAVE KEPT PRECIPITATION CHANCES BETWEEN 20 AND 30. A LOT OF UNCERTAINTY EXISTS WITH THIS DAKOTAS SHORTWAVE HEADING INTO THURSDAY NIGHT...WHERE THE 27.00Z ECMWF/UKMET DROP IT DOWN INTO MISSOURI WHEREAS THE 27.00Z GFS CROSSES IOWA AND THE 27.00Z NAM CROSSES THE FORECAST AREA. FEELING IS THE SOUTHERN SOLUTIONS MAY HAVE A BETTER CHANCE OF VERIFYING...DUE TO THE USUAL BETTER PREDICTABILITY OF THE ECMWF...BUT NOT COMPLETELY SURE GIVEN THE FAST FLOW. THEREFORE...20 TO 30 PERCENT CHANCES CONTINUE FOR THURSDAY NIGHT. WITH SO MUCH UNCERTAINTY ON THE TRACKS OF THESE SHORTWAVES...TEMPERATURE FORECASTS ARE PROBLEMATIC. CERTAINLY POTENTIAL EXISTS ON THURSDAY FOR AT LEAST THE SOUTHERN PORTION OF THE AREA TO HIT 40 OR HIGHER...ESPECIALLY IF THE SHORTWAVE THEN TRACKS FARTHER NORTH. CLOUDS THURSDAY NIGHT SHOULD HOLD TEMPERATURES UP IN THE 20S TO LOW 30S...COLDEST IN TAYLOR AND CLARK COUNTIES WHERE COOLER AIR SINKS SOUTH BEHIND THE SHORTWAVE MOSTLY SUGGESTED TO TRACK NEAR OR SOUTH OF THE AREA. .LONG TERM...FRIDAY THROUGH MONDAY NIGHT 305 AM CST TUE DEC 27 2011 27.00Z MODEL CYCLE CONSISTING OF THE ECMWF/GFS/CANADIAN AND GFS ENSEMBLES STILL PRESENT PLENTY OF UNCERTAINTY WITH REGARDS TO THE UPPER LEVEL PATTERN THROUGHOUT THE LONG TERM PERIOD...THOUGH THERE ARE SOME FEATURES THAT CAN BE LATCHED ONTO. THE FIRST IS A FAIRLY POTENT SHORTWAVE TROUGH POISED TO COME INTO THE PACIFIC NORTHWEST ON FRIDAY...RESULTING IN BUILDING RIDGING DOWNSTREAM TOWARDS THE FORECAST AREA. THIS RIDGING LOOKS TO BUILD INTO THE AREA FRIDAY NIGHT...BRINGING IN A SURGE OF DOWNSLOPED PACIFIC AIR. TIMING THE PACIFIC NORTHWEST SHORTWAVE TROUGH AND INTENSITY WILL BE CRITICAL IN DETERMINING HOW WARM NEW YEARS EVE IS. LOOKS LIKE THERE SHOULD BE SOME WARM ADVECTION PRECIPITATION DOWNSTREAM INTO THE AREA FRIDAY/FRIDAY NIGHT...BUT THIS MOSTLY LIFTS NORTH ON NEW YEARS EVE. THE 26.12Z/27.00Z ECMWF RUNS ARE BY FAR THE MOST AMPLIFIED... RESULTING IN A SLOWER COLD FRONTAL PASSAGE AND HIGH TEMPERATURES SATURDAY FROM THE 40S INTO THE LOW 50S. FOR NOW HAVE TAKEN A 30 DAY BIAS CORRECTION OF THE CONSENSUS OF ALL GUIDANCE...WHICH RESULTS IN HIGHS MOSTLY IN THE 40S. CERTAINLY POTENTIAL EXISTS FOR WARMER READINGS GIVEN LACK OF SNOW COVER STILL ANTICIPATED. COLDER AIR WILL MOVE INTO THE AREA FOR NEW YEARS DAY AS THE UPPER TROUGH MOVES IN...BUT HOW MUCH DEPENDS ON THE PROGRESSIVE NATURE OF THE UPPER TROUGH. THE MORE AMPLIFIED ECMWF BASICALLY TURNS THE TROUGH INTO A LONGWAVE TROUGH...ALLOWING FOR AIR OF MORE ARCTIC ORIGIN TO FLOW SOUTH INTO THE AREA FOR NEW YEARS DAY AND MONDAY. ON THE OTHER HAND...THE 27.00Z GFS/CANADIAN DEPICT MUCH MORE PROGRESSION... RESULTING IN A CONTINUED FEED OF PACIFIC AIR AND WARMER. GIVEN SO MUCH UNCERTAINTY...A CONSENSUS OF GUIDANCE WAS FOLLOWED FOR NEW YEARS DAY THROUGH MONDAY NIGHT. IN EITHER MODEL CAMP SCENARIO...IT LOOKS LIKE LITTLE IF ANY PRECIPITATION WILL OCCUR. && .AVIATION...TODAY AND TONIGHT 521 AM CST TUE DEC 27 2011 GUSTY NORTHWEST WINDS AND MVFR STRATUS ARE THE MAIN CONCERNS TODAY. A TIGHT PRESSURE GRADIENT WILL BE IN PLACE ACROSS THE AREA TODAY AS A DEEPENING LOW PRESSURE SYSTEM MOVES INTO THE GREAT LAKES REGION. THIS WILL RESULT IN NORTHWEST WINDS IN THE 15 TO 25KT RANGE WITH GUSTS AROUND 30KT. LOOK FOR THE STRATUS TO SCATTER FROM WEST TO EAST THIS AFTERNOON AS HIGH PRESSURE AND DRIER AIR MOVES IN FROM THE PLAINS. EXPECTING VFR CONDITIONS BY 20Z AT KRST AND AROUND 21Z AT KLSE. THE GUSTY WINDS WILL SUBSIDE AROUND SUNSET. LOOK FOR HIGH/MID LEVEL CLOUDS TO SPREAD INTO AND THICKEN ACROSS THE AREA THIS EVENING AND OVERNIGHT AHEAD OF A WARM FRONT MOVING ACROSS THE NORTHERN PLAINS. OTHERWISE...VFR CONDITIONS EXPECTED TO PREVAIL TONIGHT. && .ARX WATCHES/WARNINGS/ADVISORIES... 305 AM CST TUE DEC 27 2011 WI...NONE. MN...NONE. IA...NONE. && $$ SHORT TERM...AJ LONG TERM...AJ AVIATION...DAS
AREA FORECAST DISCUSSION
NWS DENVER CO
315 PM MST TUE DEC 27 2011 SHORT TERM...A MODERATE NORTHWESTERLY FLOW ALOFT REMAINS IN PLACE ACROSS THE CWFA TONIGHT. LATEST SATELLITE LOOPS INDICATE WEAK SHORTWAVE OVER WYOMING WITH THE TAIL END EXTENDING INTO NORTHWEST COLORADO. AT THIS TIME RADAR`S NOT SHOWING MUCH IN THE WAY OF PRECIP AND SURFACE OBS NOT REPORTING ANY SNOWFALL. LATEST RUC AND NAM QG VERTICAL VELOCITY PROGS SHOW SOME WEAK ASCENT IN THE MID LEVELS ACROSS THE NORTHERN TIER OF COLORADO AS IT MOVES ACROSS THE AREA THROUGH THE EARLY EVENING. MODEL CROSS SECTIONS THROUGH THE EVENING SHOW SOME INCREASE IN MOISTURE ALONG WITH FAIRLY DECENT OROGRAPHICS. STILL THINK THE COMBINATION OF ASCENT AND OROGRAPHICS WILL BE ENOUGH TO GENERATE SOME LIGHT SNOW...THOUGH NO QPF/SNOW INDICATED VIA THE MODELS. CROSS SECTIONS ALSO INDICATE AN INCREASE IN WINDS THROUGH 03Z WITH A PEAK OF CROSS MOUNTAIN FLOW OF 50 KTS AROUND 00Z. THE GUSTY WINDS SHOULD CREATE SOME BLOWING SNOW ACROSS THE MOUNTAINS AS WELL AS IN AND NEAR THE FOOTHILLS...MAINLY OVER THE HIGHER PASSES WHERE THERE IS DECENT SNOW COVER. WILL KEEP THE MENTION OF BLOWING SNOW IN THE GRIDS THROUGH 03Z. THE BLOWING SNOW LOOKS TO BE LESS OF AN ISSUE AND RATHER LOCALIZED FOR ZONE 39...BUT ENOUGH OF A THREAT TO KEEP IN THE GRIDS. BASED ON MODEL CROSS SECTIONS...SHOULD SEE A DECREASE IN WINDS AFTER 03Z AS CROSS MOUNTAIN FLOW DECREASES TO AROUND 35 KTS AT MOUNTAIN TOP. DROPPED THE SLIGHT CHANCE OF MOUNTAIN SNOW AFTER MIDNIGHT DUE TO THE LACK OF MOISTURE AND QG ASCENT. AS FOR THE PLAINS DRY CONDITIONS TO PREVAIL TONIGHT WITH DECREASING WINDS NEAR THE FOOTHILLS. ON WEDNESDAY...A MODERATE WEST TO NORTHWEST FLOW ALOFT PREVAILS OVER THE CFWA. MODELS SHOW ANOTHER WEAK SHORTWAVE SLIDING INTO IDAHO AND WESTERN WYOMING BY THE AFTERNOON. SOME INCREASE IN MID LEVEL MOISTURE NOTED ON CROSS SECTIONS OVER THE MOUNTAINS AFTER 18Z ALONG WITH SOME FAVORABLE OROGRAPHICS...BUT LAPSE RATES LOOK LOW AND QG VERTICAL PROGS INDICATING MINIMAL ASCENT. ANY SNOW CHANCES FOR THE MOUNTAINS LOOK LOW...WILL KEEP THE SLIGHT CHANCE FOR ZONES 31 AND 33 DURING THE AFTERNOON. AS FOR PLAINS...DRY CONDITIONS TO PREVAIL WITH SOME INCREASE IN HIGH LEVEL MOISTURE. NAM SHOWS SOME SURFACE WINDS TO AROUND 25 KTS NEAR THE WYOMING BORDER DURING THE AFTERNOON...OTHERWISE WINDS SHOULD BE FAIRLY LIGHT. TEMPERATURE AND THICKNESS PROGS SUGGEST HIGHS AROUND 50 ACROSS THE PLAINS...WITH LOWER 50S NEAR THE EASTERN BORDER ZONES. GUIDANCE TEMPERATURES SEEM A BIT TOO WARM WILL UNDERCUT A BIT WHERE THERE REMAINS SNOW COVER. .LONG TERM...A CHANCE OF SNOW WILL CONTINUE OVER MAINLY THE NORTHERN MOUNTAINS WEDNESDAY NIGHT THEN SPREAD SOUTH OF INTERSTATE 70 DURING THE DAY THURSDAY AS THE SHORTWAVE MOVES IN. AMOUNTS LOOK TO BE THE GREATEST OVER THE MOUNTAINS NEAR STEAMBOAT WITH BETWEEN 4 TO 6 INCHES FALLING BETWEEN WEDNESDAY AFTERNOON THROUGH THURSDAY NIGHT. AMOUNTS WILL BE LESS ELSEWHERE. ALSO WITH THE SHORTWAVE...WINDS OVER THE EASTERN MOUNTAINS AND ALONG THE FOOTHILLS WILL BE INCREASING. A DEEPENING SURFACE TROUGH OVER THE EASTERN PLAINS COMBINED WITH DOWNWARD QG MOTION AND A 130 KT JET NEARBY WILL BRING DOWNSLOPING GUSTS UP TO 65 MPH POSSIBLE OVER THE HIGHER TERRAIN EAST OF THE DIVIDE...ESPECIALLY OVER LARIMER AND BOULDER COUNTIES. WILL HOLD OFF ON ISSUING ANY HIGHLIGHTS...HOWEVER THE LATEST NAM MODEL THAT JUST CAME IN IS PLACING THE JET CLOSER OVERHEAD WHICH WOULD ALLOW STRONGER WINDS. WILL SEE IF OTHER MODELS FOLLOW SUIT. TEMPERATURES ON THURSDAY WILL WARMER DUE TO THE DOWNSLOPING WARMING...SHOULD SEE 50S OVER THE PLAINS WITH READINGS NEAR 60 OVER THE FAR NORTHEASTERN PLAINS. THE MINIMUM TEMPERATURES THAT NIGHT WILL ALSO REMAIN WARM. AN UPPER RIDGE WILL MOVE OVERHEAD ON FRIDAY TO KEEP IN THE WARM TEMPERATURES AND DRY CONDITIONS. CLOSE ON ITS HEELS HOWEVER WILL BE ANOTHER SHORTWAVE IN THE CONSTANT NORTHWEST FLOW ALOFT. THIS WILL BRING ANOTHER ROUND OF SNOW TO THE NORTHERN MOUNTAINS AND WINDY CONDITIONS SPREADING INTO THE FOOTHILLS...BUT WITH LIGHTER SPEEDS THAN THURSDAY. THE CHANCE OF SNOW WILL LAST INTO SATURDAY BEFORE A BIGGER UPPER RIDGE IS PROGGED TO MOVE OVER THE WESTERN STATES TO BRING WARM AND DRY WEATHER TO NORTHEASTERN COLORADO THROUGH THE WEEKEND AND INTO THE FIRST HALF OF NEXT WEEK...AND THE NEW YEAR. && AVIATION...VFR CONDITIONS TO CONTINUE THROUGH WEDNESDAY WITH VARYING AMOUNTS OF MAINLY HIGH LEVEL CLOUDS. SURFACE WINDS SHOULD WEAKEN DURING THE EVENING AND BECOME SOUTHWEST BY 03Z AS DRAINAGE PATTERN DEVELOPS. EXCEPTION WILL BE AT KBJC WHERE WESTERLY WINDS WILL PREVAIL OVERNIGHT WITH SOME GUSTS TO 30 KTS THROUGH 06Z. ON WEDNESDAY...SOUTHWEST SURFACE GRADIENT TO PREVAIL...WITH SPEEDS AROUND 12KTS. SOME GUSTS TO 20 KTS POSSIBLE AT KBJC...MAINLY IN THE MORNING. && .BOU WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHORT TERM...D-L LONG TERM....KRIEDERMAN AVIATION...D-L
AREA FORECAST DISCUSSION
NWS ALBANY NY
114 PM EST TUE DEC 27 2011 .SYNOPSIS... AN AREA OF LOW PRESSURE WILL TRACK NORTHEAST ACROSS OUR REGION THIS AFTERNOON AND TONIGHT WITH WIDESPREAD PRECIPITATION AND BREEZY CONDITIONS. MAINLY RAIN IS EXPECTED FROM THIS SYSTEM...BUT AREAS WELL NORTH AND WEST OF ALBANY WILL GET SOME LIGHT SNOW ACCUMULATIONS...ESPECIALLY TONIGHT...AS RAIN CHANGES TO SNOW. VERY WINDY AND COLDER CONDITIONS WITH SCATTERED TO NUMEROUS SNOW AND OR RAIN SHOWERS WILL OCCUR WEDNESDAY...AS THE STORM MOVES INTO EASTERN CANADA. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... CLOUDS HAVE PRETTY MUCH SPREAD OVER THE ENTIRE AREA...AND AREA RADARS SHOWING SOME VIRGA. NO PRECIPITATION IS REACHING THE GROUND OVER THE REGION YET...BUT SHOULD DEVELOP OVERHEAD THROUGH THE AFTERNOON. TEMPERATURES HAVE WARMED RAPIDLY...BUT WITH THE CLOUD COVER AND EVENTUAL RAIN...TEMPERATURES SHOULD RISE ONLY A DEGREE OR TWO MORE THROUGH THIS AFTERNOON. CURRENT OBSERVATIONS AND TRENDS SUPPORT MOST OF THE CURRENT FORECAST THROUGH THIS AFTERNOON...SO FEW CHANGES NEEDED IF ANY. REV AFD BELOW... AS OF 950 AM EDT...LOW PRESSURE CONTINUES TO RAPIDLY FORM NEAR THE SRN APPALACHIANS THIS HOUR. THE BEST MSAS PRESSURE FALLS ARE NEAR W-CNTRL NC. THE WATER VAPOR LOOP HAS A SHORT-WAVE ROTATING AROUND A STRONG SOUTHERN STREAM NEGATIVELY TILTED UPPER TROUGH. A NORTHERN STREAM DISTURBANCE IS ALSO TRYING TO PHASE IN. A DUAL UPPER LEVEL JET STREAK STRUCTURE IS IN PLACE WITH THE STORM DEEPENING AND INTENSIFYING ALONG THE LEFT FROM QUADRANT OF A H250 JET STREAK OF 100+ KTS...AND A 140+ KT JET STREAM IS MOVING ACROSS SRN QUEBEC. THE LOW LEVEL JET WILL INCREASE AHEAD OF THE WAVE. THE H850 WINDS INCREASE TO 45-60 KTS BTWN 18Z-00Z. WE INCREASED THE S/SE WINDS TO 10 TO 20 MPH WITH SOME GUSTS IN THE 30-40 MPH LATE THIS PM AND EARLY THIS EVENING. THE STRONGEST WINDS LOOK LIKE THESE WILL BE ALONG THE SRN GREENS...ERN CATSKILLS...AND PORTIONS OF THE MOHAWK VALLEY INTO THE SRN DACKS. WE SLIGHTLY RETOOLED THE POPS BASED ON THE LATEST HRRR AND NAM12 WITH AN ONSET IN THE 21Z- 00Z TIME FRAME. THIS WAVE IS A FAST MOVER. THE DRY SLOT MAY REACH THE FCST AREA AS EARLY AS 03Z ! THE NAM SHOWS SOME ELEVATED INSTABILITY GRAZING THE SOUTHEAST EXTREME OF THE FCST AREA WITH SHOWALTER VALUES OF 0 TO -1C. THERE MAYBE A RUMBLE OF THUNDER SOUTH AND EAST OF THE CAPITAL REGION EARLY THIS EVENING. WE DID NOT ADD THUNDER TO THE GRIDS YET DUE TO LOW CONFIDENCE AND A SMALL PROBABILITY. FINALLY...A LOOK AT THE CRITICAL THICKNESSES AND MODEL SOUNDINGS INDICATE MAINLY A RAIN PTYPE WITH SOME SNOW TRANSITIONING TO RAIN...THEN BACK TO SNOW OVER THE SRN AND WRN ADIRONDACKS. THERE IS A VERY SMALL CHC OF A BRIEF PERIOD OF SOME POCKETS OF -FZRA IN THE SRN DACKS...BUT WE WERE NOT CONFIDENT TO ADD THIS PTYPE AT THIS TIME. TOTAL SNOWFALL AMOUNTS IN THE SRN DACKS WILL BE IN THE 2 TO 5 INCH RANGE. T/TD/RH/APPARENT TEMPS WERE REDONE BASED ON OBSERVATIONS...AND CLOUDS WERE RETOOLED BASED ON THE VIS/IR PICTURE...AS MID AND HIGH CLOUDS CONTINUES TO THICKEN AND LOWER. PREVIOUS NEAR TERM... AS OF 600 AM...HAVE MADE SOME ADJUSTMENTS TO THE HOURLY TEMP GRIDS...WITH LITTLE ELSE CHANGED. 06Z NAM/GFS ARE NOW IN...AND THEY CONTINUE TO SHOW A STORM TRACK THAT IS OVER THE NORTHWEST PART OF THE FORECAST AREA...SO WARM MOSTLY RAIN SOLUTION USED EARLIER TO PRODUCE THE FORECAST STILL LOOKS GOOD. ****PREVIOUS DISCUSSION**** HAVE WORKED THE PAST FEW NIGHTS AND HAVE SEEN THE MODELS CONTINUE THEIR TREND OF TRACKING THE UPCOMING STORM FURTHER AND FURTHER TO THE WEST. THE CURRENT 00Z RUNS ARE ALL NOW FORECASTING THE LOW TO PASS TO THE NORTH AND WEST OF ALBANY. WITH NO RETREATING FRIGID ARCTIC AIR MASS IN PLACE OVER THE REGION...THE WARMING THAT WILL RESULT FROM SUCH A TRACK WILL PRODUCE MOSTLY RAIN ACROSS THE FORECAST AREA...EVEN THE ADIRONDACK PART OF THE FORECAST AREA. RAIN WILL BEGIN TO SPREAD INTO THE FORECAST AREA FROM THE SOUTHWEST BY AROUND 200 PM...AND SPREAD SO RAPIDLY NORTHEAST THAT BY 5 OR 6 PM WIDESPREAD RAINFALL WILL BE FALLING ACROSS THE ENTIRE FORECAST AREA. A MIX OF SNOW AND RAIN IS POSSIBLE OVER THE FAR NORTHWEST PART OF THE FORECAST AREA...WHICH MAY CONTINUE THROUGH THE EVENING AS A MIX...THEN CHANGE TO ALL SNOW THERE AROUND OF AFTER 06Z TONIGHT. BY THE TIME THE CHANGEOVER TO ALL SNOW BEGINS...THE BULK OF THE PCPN WILL HAVE ALREADY PASSED...SO AM EXPECTING NO MORE THAN 1 TO 4 INCHES OF SNOW ACROSS HERKIMER... HAMILTON...NORTHERN FULTON AND NORTHERN WARREN COUNTIES. ELSEWHERE...RAIN MAY CHANGE TO SNOW BEFORE PCPN ENDS AS WELL...BUT IT WILL OCCUR SO LATE THAT LITTLE IF ANY ACCUMULATION IS EXPECTED. AN INCH OR LESS HAS BEEN FORECAST IN THE CENTRAL MOHAWK VALLEY...THE SCHOHARIE VALLEY AND EASTERN CATSKILLS LATE TONIGHT...WITH LITTLE OR NO SNOW ELSEWHERE. NO WINTER WEATHER ADVISORIES HAVE BEEN ISSUED AT THIS TIME SINCE SNOWFALL AMOUNTS ARE LESS THAN THE ADVISORY CRITERIA. HOWEVER...SINCE WE HAVE BEEN HIGHLIGHTING THIS EVENT IN THE HWOALY PRODUCT FOR THE PAST FEW DAYS...CONTINUED TO MENTION THE SNOW ACCUMULATIONS IN THE LATEST HWOALY. MODEL WIND FORECASTS AT 925 MB AND 850 INDICATE SOUTHERLY WINDS AT THOSE LEVELS WILL INCREASE TO 40 TO 50 KTS LATE TODAY AND THIS EVENING. HOWEVER...MOS WIND FORECASTS AND MODEL SOUNDINGS INDICATE THAT THESE STRONG WINDS ARE NOT LIKELY TO TRANSLATE DOWN TO THE SURFACE DUE TO THE RAIN/PCPN INDUCED LOW LEVEL INVERSION THAT IS LIKELY TO DEVELOP AFTER THE PCPN BEGINS. DAY SHIFT WILL NEED TO MONITOR FOR THE POSSIBILITY THAT THE STRONG SOUTHERLY WINDS ALOFT MAY MIX DOWN TO THE SURFACE...ESPECIALLY IF ANY CONVECTIVE ELEMENTS BEGIN TO DEVELOP LATER TODAY AS THE PCPN APPROACHES. TEMPS TODAY WILL RISE INTO THE UPPER 30S AND 40S BY LATE IN THE DAY...AND GENERALLY REMAIN AT THOSE LEVELS UNTIL THE SURFACE LOW MOVES BY AND WESTERLY WINDS BRING COLDER AIR IN. THIS IS NOT LIKELY TO HAPPEN UNTIL AROUND OR AFTER 06Z TONIGHT. BY SUNRISE WEDNESDAY MORNING...TEMPS WILL EVENTUALLY DROP INTO THE 20S OVER THE NORTHWEST...AND 30S ELSEWHERE. && .SHORT TERM /6 PM THIS EVENING THROUGH THURSDAY/... TYPICAL BLUSTERY CONDITIONS WITH SCATTERED TO NUMEROUS SNOW SHOWERS ACROSS THE REGION ON WEDNESDAY IN THE WAKE OF THE STORM...ESPECIALLY OVER HIGHER TERRAIN AND DOWNWIND OF LAKE ONTARIO. ANOTHER INCH OR TWO OF SNOW IS POSSIBLE FROM THE ADIRONDACKS TO THE MOHAWK AND SCHOHARIE VALLEYS AND EASTERN CATSKILLS ON WEDNESDAY...WITH LESSER AMOUNTS ELSEWHERE. MODELS CONTINUE TO SHOW 925 AND 850 WINDS IN THE 40 TO 50 KT RANGE ON WEDNESDAY...BUT WITH THE MIXING OF THE NOW WEST TO NORTHWEST WINDS DOWN TO THE SURFACE MUCH MORE LIKELY...THERE IS A BETTER CHANCE THAT A WIND ADVISORY MAY BE NEEDED ON WEDNESDAY...AND IT HAS BEEN HIGHLIGHTED IN THE HWOALY PRODUCT ACROSS THE ENTIRE FORECAST AREA. HAVE CURRENTLY FORECAST WINDS OF 15 TO 30 MPH WITH GUSTS OF 35 TO 45 MPH. TEMPS WEDNESDAY MAY ACTUALLY FALL OR REMAIN STEADY AS COLDER AIR SURGES IN. HAVE INDICATED HIGHS ON WEDNESDAY ONLY ABOUT A DEGREE OR TWO HIGHER THAN THE LOWS WEDNESDAY MORNING. WINDS AND SNOW SHOWERS WILL DIMINISH WEDNESDAY EVENING. EXPECT LEFTOVER SNOW SHOWERS TO COMPLETELY END DURING THE EVENING...BUT A DECENT WIND WILL CONTINUE THROUGH THE NIGHT WITH WIND GUSTS OF 25 TO 30 MPH POSSIBLE THROUGH WELL AFTER MIDNIGHT. LOWS WEDNESDAY NIGHT WILL RANGE FROM A FEW DEGREES BELOW ZERO OVER THE ADIRONDACKS...TO THE UPPER TEENS OVER THE SOUTH. A CLIPPER LIKE SYSTEM WILL MOVE THROUGH THE GREAT LAKES ON THURSDAY...BUT IT IS NOT LIKELY TO ARRIVE IN OUR AREA UNTIL THURSDAY NIGHT. SO HAVE KEPT THE FORECAST FOR THURSDAY DRY...BUT DID INCREASE THE CLOUD COVER. HIGHS THURSDAY WILL BE IN THE 20S TO MID 30S. && .LONG TERM /THURSDAY NIGHT THROUGH TUESDAY/... A CLIPPER TYPE LOW APPROACHES THE REGION THURSDAY NIGHT RESULTING IN CLOUDY SKIES...LOW CHANCE POPS...AND LOW TEMPS FROM AROUND 10 ABOVE NORTH TO THE UPPER 20S SOUTH. PRECIP AMOUNTS...ALL SNOW... WILL BE VERY LIGHT AS THE THE SYSTEM IS MOISTURE STARVED. THE CLIPPER MOVES ACROSS THE REGION ON FRIDAY. THE GFS IS MORE PROGRESSIVE THAN THE ECMWF WHICH SLOWS DOWN THE MOVEMENT OF THE CLIPPER AND MOVES IT FARTHER SOUTH. WARMER AIR IS DRAWN IN AHEAD OF THE CLIPPER WHICH CHANGES THE PRECIP FROM SNOW TO RAIN OVER MUCH OF THE REGION AND INCREASES THE PRECIP AMOUNTS TO THE SOUTH OF THE RAIN SNOW LINE. HIGHS FRIDAY WILL RANGE FROM AROUND 30 NORTH TO THE LOW 40S SOUTH. THE PASSAGE OF THE CLIPPER WILL BE FOLLOWED BY A SURGE OF COLD AIR WITH 850 TEMPS AROUND MINUS 10 WITH LOWS FRIDAY NIGHT FROM THE HIGH SINGLES NORTH TO THE MID 20S SOUTH. WESTERLY WINDS WILL RESULT IN A CHANCE FOR SOME LAKE ENHANCED PRECIP WITH THE COLD ADVECTION WEST...ENOUGH FOR CHANCE POPS DOWN THE MOHAWK VALLEY AND ELEVATED TERRAIN WEST OF THE HUDSON VALLEY...WITH ONLY SLIGHT CHANCE POPS FARTHER EAST. HIGHS SATURDAY WILL RANGE FROM THE MID 20S TO AROUND 40. HIGH PRESSURE BRIEFLY CROSSES THE REGION SATURDAY INTO SATURDAY NIGHT AND WINDS BACK AROUND TO A SOUTHWESTERLY DIRECTION BRINGING WARMER AIR INTO THE REGION. LOWS SATURDAY NIGHT WILL RANGE FROM AROUND 20 NORTH TO 30 SOUTH. THE NEXT IN A SERIES OF CLIPPERS MOVES ACROSS CANADA NORTH OF THE REGION ON SUNDAY...BRINGING A MIXED BAG OF RAIN AND SNOW SHOWERS DEPENDING ON THE LATITUDE... ELEVATION...AND TIME OF DAY. HIGHS SUNDAY WILL RANGE FROM THE MID 30S NORTH TO THE LOWER 40S SOUTH. AS THE LOW MOVES EAST IT BRINGS ANOTHER BLAST OF COLD IN ITS WAKE...CHANGING THE RAIN TO SNOW SUNDAY EVENING. LOWS SUNDAY NIGHT WILL RANGE FROM THE LOWER TEENS TO THE MID 20S. MONDAY LOOKS TO BE BLUSTERY AND COLD WITH BRISK NORTHWEST WINDS 15 TO 25 MPH DURING THE MIDDAY PERIOD AND HIGHS ONLY FROM AROUND 20 NORTH TO THE UPPER 30S SOUTH. && .AVIATION /18Z TUESDAY THROUGH SUNDAY/... LOW PRESSURE CONTINUES TO DEEPEN AND INTENSIFY NEAR THE PIEDMONT REGION THIS AFTERNOON. THE CYCLONE WILL QUICKLY MOVE NORTHEAST ACROSS CENTRAL NY THIS EVENING...AND INTO SOUTHEAST QUEBEC AFTER MIDNIGHT. VFR FLIGHT CONDITIONS WILL PERSIST PRIOR TO SUNSET...THEN CONDITIONS WILL DETERIORATE BETWEEN 21Z TO 00Z WITH THE THERMAL ADVECTION RAINFALL AHEAD OF THE INTENSIFYING CYCLONE. CONDITIONS WILL LOWER TO MVFR VIS/CIG LEVELS...AND POTENTIALLY IFR LEVELS AT KPOU PRIOR TO 00Z. THERE IS A MODERATE PROBABILITY THAT CONDITIONS MAY DECREASE TO IFR LEVELS AT KALB AND KGFL BTWN 00Z-06Z/WED IN THE PCPN SHIELD AHEAD OF THE WAVE. WE KEPT KALB AT LOW MVFR LEVELS...AND LOWERED KGFL ALONG WITH KPOU TO IFR CONDITIONS IN THAT TIME FRAME. THE DRY SLOT TO THE SYSTEM MOVES INTO CNTRL-ERN NY AROUND MIDNIGHT. THE PCPN WILL END AND CONDITIONS WILL RISE TO MVFR LEVELS AT ALL THE SITES. CIGS WILL HANG AT HIGH MVFR AT KALB NORTH TO KGFL LATE AND THE MORNING...WITH KPOU RISING TO LOW VFR CIGS LEVELS AFTER SUNRISE. LOW LEVEL WIND SHEAR WILL BE AT LEAST A FACTOR AT KPOU BTWN 21Z- 04Z WITH THE 2 KFT AGL WINDS INCREASING TO 40-50 KTS. WE ADDED LLWS GROUPS THERE. THE SFC WINDS WILL GENERALLY BE 10 KTS OR LESS. FOR KALB AND KGFL...THE WINDS WILL BE FROM S/SE AT 8-15 KTS. THE 2 KFT AGL WINDS ARE EXPECTED TO BE AROUND 30-35 KTS. OVERALL THE WINDS WILL BACK FROM THE S/SE TO THE E/NE AT 5-10 KTS. EARLY THIS EVENING. THEY WILL VEER TO THE SW AFTER MIDNIGHT AT AROUND 10 KTS. THE WINDS WILL INCREASE FROM THE WEST AFTER 12Z AT 12-18 KTS WITH SOME GUSTS GREATER THAN 25 KTS /ESPECIALLY AT KALB DUE TO FUNNELING DOWN THE MOHAWK RIVER VALLEY/ WITH THE LOW LEVEL PRESSURE GRADIENT INCREASING BETWEEN THE DEPARTING STORM AND HIGH PRESSURE BUILDING IN FROM THE LOWER MS RIVER VALLEY. ALSO...THE BUFKIT MOMENTUM TRANSFER PROFILES INDICATED GUSTS GREATER THAN 30 KTS MAY BE NEEDED IN THE AFTERNOON. OUTLOOK... WED PM...MVFR IMPROVING TO VFR. WINDY THU...VFR. NO SIG WX. FRI...VFR/MVFR...CHC -SHSN/-SHRA. SAT- SUN...VFR...SLIGHT CHC -SHSN/-SHRA. && .HYDROLOGY... WHILE A SOAKING RAIN OF UP TO AROUND AN INCH IS EXPECTED THROUGH TONIGHT...IT IS NOT EXPECTED TO RESULT IN FLOODING. RAIN IS EXPECTED TO START LATE THIS AFTERNOON AND CONTINUE THROUGH TONIGHT. THE RAIN WILL MIX WITH AND CHANGE TO SNOW WELL NORTH AND WEST OF THE ALBANY AREA. HEAVIEST RAINFALL AMOUNTS ARE EXPECTED IN THE MID HUDSON REGION OF NEW YORK AND OVER THE HOUSATONIC VALLEY AND LITCHFIELD HILLS OF CONNECTICUT. MODEST RISES MAY BE EXPECTED ON THE RIVERS AND STREAMS IN THIS AREA...BUT THE RAIN IS NOT EXPECTED TO BE HEAVY ENOUGH TO BRING RIVERS UP TO FLOOD. DRY WEATHER ON THURSDAY WILL ALLOW RIVERS AND STREAMS TO RECEDE. A SERIES OF CLIPPER TYPE LOWS OVER THE NEW YEARS WEEKEND WILL HAVE LITTLE EFFECT ON THE RIVERS SINCE MOISTURE WILL BE LACKING WITH THEM. 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...NAS NEAR TERM...NAS SHORT TERM...GJM LONG TERM...RCK AVIATION...WASULA HYDROLOGY...RCK
AREA FORECAST DISCUSSION
NWS ALBANY NY
1223 PM EST TUE DEC 27 2011 .SYNOPSIS... AN AREA OF LOW PRESSURE WILL TRACK NORTHEAST ACROSS OUR REGION THIS AFTERNOON AND TONIGHT WITH WIDESPREAD PRECIPITATION AND BREEZY CONDITIONS. MAINLY RAIN IS EXPECTED FROM THIS SYSTEM...BUT AREAS WELL NORTH AND WEST OF ALBANY WILL GET SOME LIGHT SNOW ACCUMULATIONS...ESPECIALLY TONIGHT...AS RAIN CHANGES TO SNOW. VERY WINDY AND COLDER CONDITIONS WITH SCATTERED TO NUMEROUS SNOW AND OR RAIN SHOWERS WILL OCCUR WEDNESDAY...AS THE STORM MOVES INTO EASTERN CANADA. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... CLOUDS HAVE PRETTY MUCH SPREAD OVER THE ENTIRE AREA...AND AREA RADARS SHOWING SOME VIRGA. NO PRECIPITATION IS REACHING THE GROUND OVER THE REGION YET...BUT SHOULD DEVELOP OVERHEAD THROUGH THE AFTERNOON. TEMPERATURES HAVE WARMED RAPIDLY...BUT WITH THE CLOUD COVER AND EVENTUAL RAIN...TEMPERATURES SHOULD RISE ONLY A DEGREE OR TWO MORE THROUGH THIS AFTERNOON. CURRENT OBSERVATIONS AND TRENDS SUPPORT MOST OF THE CURRENT FORECAST THROUGH THIS AFTERNOON...SO FEW CHANGES NEEDED IF ANY. REV AFD BELOW... AS OF 950 AM EDT...LOW PRESSURE CONTINUES TO RAPIDLY FORM NEAR THE SRN APPALACHIANS THIS HOUR. THE BEST MSAS PRESSURE FALLS ARE NEAR W-CNTRL NC. THE WATER VAPOR LOOP HAS A SHORT-WAVE ROTATING AROUND A STRONG SOUTHERN STREAM NEGATIVELY TILTED UPPER TROUGH. A NORTHERN STREAM DISTURBANCE IS ALSO TRYING TO PHASE IN. A DUAL UPPER LEVEL JET STREAK STRUCTURE IS IN PLACE WITH THE STORM DEEPENING AND INTENSIFYING ALONG THE LEFT FROM QUADRANT OF A H250 JET STREAK OF 100+ KTS...AND A 140+ KT JET STREAM IS MOVING ACROSS SRN QUEBEC. THE LOW LEVEL JET WILL INCREASE AHEAD OF THE WAVE. THE H850 WINDS INCREASE TO 45-60 KTS BTWN 18Z-00Z. WE INCREASED THE S/SE WINDS TO 10 TO 20 MPH WITH SOME GUSTS IN THE 30-40 MPH LATE THIS PM AND EARLY THIS EVENING. THE STRONGEST WINDS LOOK LIKE THESE WILL BE ALONG THE SRN GREENS...ERN CATSKILLS...AND PORTIONS OF THE MOHAWK VALLEY INTO THE SRN DACKS. WE SLIGHTLY RETOOLED THE POPS BASED ON THE LATEST HRRR AND NAM12 WITH AN ONSET IN THE 21Z- 00Z TIME FRAME. THIS WAVE IS A FAST MOVER. THE DRY SLOT MAY REACH THE FCST AREA AS EARLY AS 03Z ! THE NAM SHOWS SOME ELEVATED INSTABILITY GRAZING THE SOUTHEAST EXTREME OF THE FCST AREA WITH SHOWALTER VALUES OF 0 TO -1C. THERE MAYBE A RUMBLE OF THUNDER SOUTH AND EAST OF THE CAPITAL REGION EARLY THIS EVENING. WE DID NOT ADD THUNDER TO THE GRIDS YET DUE TO LOW CONFIDENCE AND A SMALL PROBABILITY. FINALLY...A LOOK AT THE CRITICAL THICKNESSES AND MODEL SOUNDINGS INDICATE MAINLY A RAIN PTYPE WITH SOME SNOW TRANSITIONING TO RAIN...THEN BACK TO SNOW OVER THE SRN AND WRN ADIRONDACKS. THERE IS A VERY SMALL CHC OF A BRIEF PERIOD OF SOME POCKETS OF -FZRA IN THE SRN DACKS...BUT WE WERE NOT CONFIDENT TO ADD THIS PTYPE AT THIS TIME. TOTAL SNOWFALL AMOUNTS IN THE SRN DACKS WILL BE IN THE 2 TO 5 INCH RANGE. T/TD/RH/APPARENT TEMPS WERE REDONE BASED ON OBSERVATIONS...AND CLOUDS WERE RETOOLED BASED ON THE VIS/IR PICTURE...AS MID AND HIGH CLOUDS CONTINUES TO THICKEN AND LOWER. PREVIOUS NEAR TERM... AS OF 600 AM...HAVE MADE SOME ADJUSTMENTS TO THE HOURLY TEMP GRIDS...WITH LITTLE ELSE CHANGED. 06Z NAM/GFS ARE NOW IN...AND THEY CONTINUE TO SHOW A STORM TRACK THAT IS OVER THE NORTHWEST PART OF THE FORECAST AREA...SO WARM MOSTLY RAIN SOLUTION USED EARLIER TO PRODUCE THE FORECAST STILL LOOKS GOOD. ****PREVIOUS DISCUSSION**** HAVE WORKED THE PAST FEW NIGHTS AND HAVE SEEN THE MODELS CONTINUE THEIR TREND OF TRACKING THE UPCOMING STORM FURTHER AND FURTHER TO THE WEST. THE CURRENT 00Z RUNS ARE ALL NOW FORECASTING THE LOW TO PASS TO THE NORTH AND WEST OF ALBANY. WITH NO RETREATING FRIGID ARCTIC AIR MASS IN PLACE OVER THE REGION...THE WARMING THAT WILL RESULT FROM SUCH A TRACK WILL PRODUCE MOSTLY RAIN ACROSS THE FORECAST AREA...EVEN THE ADIRONDACK PART OF THE FORECAST AREA. RAIN WILL BEGIN TO SPREAD INTO THE FORECAST AREA FROM THE SOUTHWEST BY AROUND 200 PM...AND SPREAD SO RAPIDLY NORTHEAST THAT BY 5 OR 6 PM WIDESPREAD RAINFALL WILL BE FALLING ACROSS THE ENTIRE FORECAST AREA. A MIX OF SNOW AND RAIN IS POSSIBLE OVER THE FAR NORTHWEST PART OF THE FORECAST AREA...WHICH MAY CONTINUE THROUGH THE EVENING AS A MIX...THEN CHANGE TO ALL SNOW THERE AROUND OF AFTER 06Z TONIGHT. BY THE TIME THE CHANGEOVER TO ALL SNOW BEGINS...THE BULK OF THE PCPN WILL HAVE ALREADY PASSED...SO AM EXPECTING NO MORE THAN 1 TO 4 INCHES OF SNOW ACROSS HERKIMER... HAMILTON...NORTHERN FULTON AND NORTHERN WARREN COUNTIES. ELSEWHERE...RAIN MAY CHANGE TO SNOW BEFORE PCPN ENDS AS WELL...BUT IT WILL OCCUR SO LATE THAT LITTLE IF ANY ACCUMULATION IS EXPECTED. AN INCH OR LESS HAS BEEN FORECAST IN THE CENTRAL MOHAWK VALLEY...THE SCHOHARIE VALLEY AND EASTERN CATSKILLS LATE TONIGHT...WITH LITTLE OR NO SNOW ELSEWHERE. NO WINTER WEATHER ADVISORIES HAVE BEEN ISSUED AT THIS TIME SINCE SNOWFALL AMOUNTS ARE LESS THAN THE ADVISORY CRITERIA. HOWEVER...SINCE WE HAVE BEEN HIGHLIGHTING THIS EVENT IN THE HWOALY PRODUCT FOR THE PAST FEW DAYS...CONTINUED TO MENTION THE SNOW ACCUMULATIONS IN THE LATEST HWOALY. MODEL WIND FORECASTS AT 925 MB AND 850 INDICATE SOUTHERLY WINDS AT THOSE LEVELS WILL INCREASE TO 40 TO 50 KTS LATE TODAY AND THIS EVENING. HOWEVER...MOS WIND FORECASTS AND MODEL SOUNDINGS INDICATE THAT THESE STRONG WINDS ARE NOT LIKELY TO TRANSLATE DOWN TO THE SURFACE DUE TO THE RAIN/PCPN INDUCED LOW LEVEL INVERSION THAT IS LIKELY TO DEVELOP AFTER THE PCPN BEGINS. DAY SHIFT WILL NEED TO MONITOR FOR THE POSSIBILITY THAT THE STRONG SOUTHERLY WINDS ALOFT MAY MIX DOWN TO THE SURFACE...ESPECIALLY IF ANY CONVECTIVE ELEMENTS BEGIN TO DEVELOP LATER TODAY AS THE PCPN APPROACHES. TEMPS TODAY WILL RISE INTO THE UPPER 30S AND 40S BY LATE IN THE DAY...AND GENERALLY REMAIN AT THOSE LEVELS UNTIL THE SURFACE LOW MOVES BY AND WESTERLY WINDS BRING COLDER AIR IN. THIS IS NOT LIKELY TO HAPPEN UNTIL AROUND OR AFTER 06Z TONIGHT. BY SUNRISE WEDNESDAY MORNING...TEMPS WILL EVENTUALLY DROP INTO THE 20S OVER THE NORTHWEST...AND 30S ELSEWHERE. && .SHORT TERM /6 PM THIS EVENING THROUGH THURSDAY/... TYPICAL BLUSTERY CONDITIONS WITH SCATTERED TO NUMEROUS SNOW SHOWERS ACROSS THE REGION ON WEDNESDAY IN THE WAKE OF THE STORM...ESPECIALLY OVER HIGHER TERRAIN AND DOWNWIND OF LAKE ONTARIO. ANOTHER INCH OR TWO OF SNOW IS POSSIBLE FROM THE ADIRONDACKS TO THE MOHAWK AND SCHOHARIE VALLEYS AND EASTERN CATSKILLS ON WEDNESDAY...WITH LESSER AMOUNTS ELSEWHERE. MODELS CONTINUE TO SHOW 925 AND 850 WINDS IN THE 40 TO 50 KT RANGE ON WEDNESDAY...BUT WITH THE MIXING OF THE NOW WEST TO NORTHWEST WINDS DOWN TO THE SURFACE MUCH MORE LIKELY...THERE IS A BETTER CHANCE THAT A WIND ADVISORY MAY BE NEEDED ON WEDNESDAY...AND IT HAS BEEN HIGHLIGHTED IN THE HWOALY PRODUCT ACROSS THE ENTIRE FORECAST AREA. HAVE CURRENTLY FORECAST WINDS OF 15 TO 30 MPH WITH GUSTS OF 35 TO 45 MPH. TEMPS WEDNESDAY MAY ACTUALLY FALL OR REMAIN STEADY AS COLDER AIR SURGES IN. HAVE INDICATED HIGHS ON WEDNESDAY ONLY ABOUT A DEGREE OR TWO HIGHER THAN THE LOWS WEDNESDAY MORNING. WINDS AND SNOW SHOWERS WILL DIMINISH WEDNESDAY EVENING. EXPECT LEFTOVER SNOW SHOWERS TO COMPLETELY END DURING THE EVENING...BUT A DECENT WIND WILL CONTINUE THROUGH THE NIGHT WITH WIND GUSTS OF 25 TO 30 MPH POSSIBLE THROUGH WELL AFTER MIDNIGHT. LOWS WEDNESDAY NIGHT WILL RANGE FROM A FEW DEGREES BELOW ZERO OVER THE ADIRONDACKS...TO THE UPPER TEENS OVER THE SOUTH. A CLIPPER LIKE SYSTEM WILL MOVE THROUGH THE GREAT LAKES ON THURSDAY...BUT IT IS NOT LIKELY TO ARRIVE IN OUR AREA UNTIL THURSDAY NIGHT. SO HAVE KEPT THE FORECAST FOR THURSDAY DRY...BUT DID INCREASE THE CLOUD COVER. HIGHS THURSDAY WILL BE IN THE 20S TO MID 30S. && .LONG TERM /THURSDAY NIGHT THROUGH MONDAY/... A CLIPPER TYPE LOW APPROACHES THE REGION THURSDAY NIGHT RESULTING IN CLOUDY SKIES...LOW CHANCE POPS...AND LOW TEMPS FROM AROUND 10 ABOVE NORTH TO THE UPPER 20S SOUTH. PRECIP AMOUNTS...ALL SNOW... WILL BE VERY LIGHT AS THE THE SYSTEM IS MOISTURE STARVED. THE CLIPPER MOVES ACROSS THE REGION ON FRIDAY. THE GFS IS MORE PROGRESSIVE THAN THE ECMWF WHICH SLOWS DOWN THE MOVEMENT OF THE CLIPPER AND MOVES IT FARTHER SOUTH. WARMER AIR IS DRAWN IN AHEAD OF THE CLIPPER WHICH CHANGES THE PRECIP FROM SNOW TO RAIN OVER MUCH OF THE REGION AND INCREASES THE PRECIP AMOUNTS TO THE SOUTH OF THE RAIN SNOW LINE. HIGHS FRIDAY WILL RANGE FROM AROUND 30 NORTH TO THE LOW 40S SOUTH. THE PASSAGE OF THE CLIPPER WILL BE FOLLOWED BY A SURGE OF COLD AIR WITH 850 TEMPS AROUND MINUS 10 WITH LOWS FRIDAY NIGHT FROM THE HIGH SINGLES NORTH TO THE MID 20S SOUTH. WESTERLY WINDS WILL RESULT IN A CHANCE FOR SOME LAKE ENHANCED PRECIP WITH THE COLD ADVECTION WEST...ENOUGH FOR CHANCE POPS DOWN THE MOHAWK VALLEY AND ELEVATED TERRAIN WEST OF THE HUDSON VALLEY...WITH ONLY SLIGHT CHANCE POPS FARTHER EAST. HIGHS SATURDAY WILL RANGE FROM THE MID 20S TO AROUND 40. HIGH PRESSURE BRIEFLY CROSSES THE REGION SATURDAY INTO SATURDAY NIGHT AND WINDS BACK AROUND TO A SOUTHWESTERLY DIRECTION BRINGING WARMER AIR INTO THE REGION. LOWS SATURDAY NIGHT WILL RANGE FROM AROUND 20 NORTH TO 30 SOUTH. THE NEXT IN A SERIES OF CLIPPERS MOVES ACROSS CANADA NORTH OF THE REGION ON SUNDAY...BRINGING A MIXED BAG OF RAIN AND SNOW SHOWERS DEPENDING ON THE LATITUDE... ELEVATION...AND TIME OF DAY. HIGHS SUNDAY WILL RANGE FROM THE MID 30S NORTH TO THE LOWER 40S SOUTH. AS THE LOW MOVES EAST IT BRINGS ANOTHER BLAST OF COLD IN ITS WAKE...CHANGING THE RAIN TO SNOW SUNDAY EVENING. LOWS SUNDAY NIGHT WILL RANGE FROM THE LOWER TEENS TO THE MID 20S. MONDAY LOOKS TO BE BLUSTERY AND COLD WITH BRISK NORTHWEST WINDS 15 TO 25 MPH DURING THE MIDDAY PERIOD AND HIGHS ONLY FROM AROUND 20 NORTH TO THE UPPER 30S SOUTH. && .AVIATION /17Z TUESDAY THROUGH SATURDAY/... VFR FLIGHT CONDITIONS AND NO AVIATION WEATHER PROBLEMS ARE EXPECTED THROUGH MID TO LATE AFTERNOON. SCATTERED HIGH CLOUDS WILL THICKEN SOME AND LOWER DURING THE MORNING HOURS...WITH AN ALTOSTRATUS DECK AROUND 15000 FT ASL BY MID TO LATE MORNING. WINDS THIS MORNING WILL BE SOUTH 5 TO 10 KNOTS THIS MORNING AND MOST OF THE AFTERNOON. AS A LOW CENTER MOVES FROM THE OHIO VALLEY INTO THE MID ATLANTIC REGION THIS AFTERNOON...CONDITIONS WILL DETERIORATE LATER THIS AFTERNOON...WITH MVFR CONDITIONS AT BEST FOR THE EVENING HOURS AS RAIN OVERSPREADS THE REGION. THE CEILING AND VISIBLITY ARE LIKELY TO LOWER TO IFR DURING THE LATE EVENING HOURS AS THE BOUNDARY LAYER BECOMES MOISTER...WITH WINDS BECOMING SOUTHEAST DURING THE LATE AFTERNOON AND EARLY EVENING. WIDESPREAD IFR MAY BE EXPECTED DURING THE NIGHTTIME HOURS DUE TO LOW CEILINGS AND POOR VISIBILITY. SOME IMPROVEMENT TO MVFR MAY TAKE PLACE LATER TONIGHT AS THE STORM LIFTS NORTH INTO CANADA. LLWS MAY BECOME A FACTOR LATE THIS AFTERNOON AND EVENING AS WINDS 2000 TO 3000 FT AGL INCREASE TO 40-55 KTS. OUTLOOK... WED...MVFR...RAIN MIXING WITH SNOW AND TAPERING OFF TO SHWRS. WINDY. THU...VFR. NO SIG WX. FRI...VFR/MVFR...CHC -SHSN/-SHRA. && .HYDROLOGY... WHILE A SOAKING RAIN OF UP TO AROUND AN INCH IS EXPECTED THROUGH TONIGHT...IT IS NOT EXPECTED TO RESULT IN FLOODING. RAIN IS EXPECTED TO START LATE THIS AFTERNOON AND CONTINUE THROUGH TONIGHT. THE RAIN WILL MIX WITH AND CHANGE TO SNOW WELL NORTH AND WEST OF THE ALBANY AREA. HEAVIEST RAINFALL AMOUNTS ARE EXPECTED IN THE MID HUDSON REGION OF NEW YORK AND OVER THE HOUSATONIC VALLEY AND LITCHFIELD HILLS OF CONNECTICUT. MODEST RISES MAY BE EXPECTED ON THE RIVERS AND STREAMS IN THIS AREA...BUT THE RAIN IS NOT EXPECTED TO BE HEAVY ENOUGH TO BRING RIVERS UP TO FLOOD. DRY WEATHER ON THURSDAY WILL ALLOW RIVERS AND STREAMS TO RECEDE. A SERIES OF CLIPPER TYPE LOWS OVER THE NEW YEARS WEEKEND WILL HAVE LITTLE EFFECT ON THE RIVERS SINCE MOISTURE WILL BE LACKING WITH THEM. 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...NAS NEAR TERM...NAS
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
241 PM CST TUE DEC 27 2011 .DISCUSSION... 1240 PM CST FOR UPDATE... HAVE MADE FEW CHANGES TO GOING FORECAST...AND THOSE MAINLY ONLY TO END LINGERING PRECIP FROM THE WEST ACROSS THE FAR EAST/SOUTHEAST PART OF THE CWA THIS MORNING. HAVE ALSO TWEAKED HOURLY/MAX TEMPS JUST A BIT...WITH SEVERAL LOCATIONS HAVING TAGGED 40 DEGREES IN THE PAST HOUR OR TWO. MAIN NEAR TERM CONCERNS ARE POTENTIAL FOR A FEW FLURRIES OR SPRINKLES THIS AFTERNOON...AS WELL AS THE POTENTIAL FOR A LITTLE LIGHT LAKE EFFECT PRECIPITATION TO DEVELOP THIS AFTERNOON INTO THIS EVENING FOR NORTHWEST INDIANA. UPPER TROUGH CONTINUES TO DEEPEN THIS AFTERNOON AS VORT DIGS SOUTHEAST ACROSS THE MID-MISSISSIPPI VALLEY. IN THE LOW LEVELS... COLD ADVECTION BEGINNING TO STRENGTHEN WHICH WILL LEAD TO STEEPENING OF LOW LEVEL LAPSE RATES IN SHALLOW MOIST LAYER BELOW ABOUT 850 HPA. COMBINATION OF WEAK DPVA ALOFT AND WEAK LOW LEVEL INSTABILITY IN CYCLONIC LOW LEVEL FLOW IS EXPECTED TO SUPPORT POTENTIAL FOR A FEW FLURRIES OR SPRINKLES ACROSS THE AREA THROUGH THE AFTERNOON. REGIONAL RADAR MOSAIC INDEED SHOWS SOME VERY WEAK RETURNS MOVING SOUTH ACROSS PORTIONS OF EASTERN WI. FORECAST SOUNDINGS INDICATE TOP OF MOIST LAYER ROUGHLY -8 TO -10 C...SO EITHER P-TYPE OF --RA OR --S POSSIBLE. VORT AXIS SHIFTS EAST OF THE AREA EARLY THIS EVENING WITH DRYING AND SUBSIDENCE BRINGING AN END TO ANY LINGERING LIGHT PCPN. LAKE EFFECT POTENTIAL IS NOT OVERLY IMPRESSIVE...THOUGH PREVIOUSLY MENTIONED PROCESSES ARE EXPECTED TO GRADUALLY INCREASE LAKE TO 850 DELTA T VALUES TO 16/17 DEG/KM THIS EVENING. LOCAL HIGH-RES WRF DEPICTS A BRIEF PERIOD OF LOW LEVEL CONVERGENCE ALONG THE SOUTH SHORE OF THE LAKE EARLY THIS EVENING...BEFORE MOIST CONVERGENCE AXIS SHIFTS EAST OF PORTER COUNTY. LIGHT QPF OUTPUT OVER MAINLY NORTHERN PORTER COUNTY SUGGESTS A LITTLE MINOR ACCUMULATION POSSIBLE...BUT WINDOW WILL PROBABLY BE FAIRLY SHORT BETWEEN DEVELOPMENT OF BETTER LAKE-INDUCED LAPSE RATES AND BEST CONVERGENCE SHIFTING EAST. RATZER //PREV DISCUSSION... 330 AM CST THE FORECAST CHALLENGES ARE FIRST ON THE IMMEDIATE SHORT TERM WITH PRECIPITATION GRADUALLY SHIFTING EASTWARD THIS MORNING...THEN THE LAKE EFFECT SHOWER POTENTIAL INTO NORTHWEST INDIANA THIS AFTERNOON AND EVENING. THE ACTIVE FLOW PATTERN ACROSS THE NORTHERN U.S. AND SOME UNDULATIONS IN THIS INTO THE NEW YEAR KEEP THE FORECAST INTERESTING LOOKING FORWARD. SHORT TERM...LOW PRESSURE IS DEVELOPING FAIRLY RAPIDLY UNDER STRONG JET SUPPORT ACROSS WESTERN KY. MOIST ADVECTION ALOFT AND ASSOCIATED ASCENT CONTINUES TO WORK ITS WAY ACROSS NORTHWEST INDIANA. AN ELONGATED NORTHERN STREAM WAVE PUSHING EAST ACROSS THE REGION HAS INTERACTED WITH THIS...HELPING TO PRODUCE BANDS OF MODERATE PRECIP AT TIMES WHERE CONVERGENCE OF ECHOES WAS OBSERVED /AND LIKELY IMPLYING FRONTOGENETIC FORCING/. WITHIN THESE...A FEW REPORTS OF SLEET WERE OBSERVED/REPORTED OR ESTIMATED THROUGH UNKNOWN PRECIP AUTOMATED REPORTS. STRONGER FORCING LIFTING NORTH ACROSS EASTERN IL/WESTERN IN HAS HELPED TO LEAD TO EVAPORATIONAL COOLING SUPPORTING SNOW...AND BENTON COUNTY REPORTED A COATING OF SNOW ON THEIR PAVEMENT AS OF 300 AM. EXPECT THE AREAS RECEIVING PRECIPITATION AT DAYBREAK TO BE MAINLY A WET SNOW...WITH A LITTLE LIGHT RAIN POSSIBLY JUST BEFORE IT ENDS ON THE WESTERN PERIPHERY. THE SHIELD OF PRECIP WILL TAKE A WHILE TO EVOLVE EAST OUT OF THE AREA BASED ON THE QG FORCING ON THE RUC AS WELL AS WATER VAPOR TRENDS WITH THE DRY SLOT NOSE LIFTING INTO CENTRAL IN HELPING TO KEEP MAINLY SNOW GOING IN THE SOUTHEAST FORECAST AREA THIS MORNING. MAXIMUM ACCUMULATIONS NEAR AN INCH TOWARDS FOWLER AND RENSSALEAR STILL LOOK VALID. IN THE FAR SOUTH AND SOUTHEAST CHICAGO METRO WHILE SNOW MAY STILL BE OCCURRING THROUGH 9 AM OR SO...NO ACCUMULATION IS EXPECTED. THIS AFTERNOON...STRONG NORTH TO NORTHWEST WINDS IN THE WAKE OF THE SYSTEM ESTABLISH THEMSELVES DOWN THE FETCH OF LAKE MI THIS AFTERNOON. CONVERGENCE STREAMLINES FROM THE 27.06 NAM FAVOR A CORRIDOR OF SATURATED CONVERGENCE CENTERED ON MICHIGAN CITY...WITH SOME FURTHER WEST TOWARDS PORTER COUNTY. LAKE INDUCED EQUILIBRIUM LEVELS ARE PROJECTED OVER 5000 FT ON THE NAM FOR LATE THIS AFTERNOON AND EVENING AND THUS HAVE INCREASED POPS IN THAT AREA FOR SOME SNOW SHOWERS. FROM THIS...ONLY AN ADDITIONAL DUSTING IS EXPECTED WITH POTENTIAL FOR MORE JUST EAST OF THE FORECAST AREA. TONIGHT THROUGH THURSDAY...THE TEMPERATURES TONIGHT WILL BE A BATTLE BETWEEN THE COLD AND DRY AIR ADVECTION THIS EVENING AND THEN MID TO HIGH CLOUDS ON THE INCREASE FROM THE WEST OVERNIGHT WITH AN APPROACHING SHORT WAVE. IN ADDITION...LINGERING STRATOCU IN THE CAA REGIME IS LIKELY EARLY THIS EVENING...AND THAT MAY RESIDE THROUGH A GOOD PART OF THE NIGHT IN EASTERN AREAS. MODEL SPREAD REFLECTS THIS...VARYING UP TO TEN DEGREES IN SOME LOCATIONS. CONFIDENCE IS THUS MINIMAL ON TONIGHTS LOWS...AND AM NEAR THE CENTER OF THE SPREAD AT THIS TIME. A STRONGER SHORT WAVE ARRIVES INTO SOUTHERN WI ON LATE WEDNESDAY NIGHT INTO THURSDAY MORNING. THIS IS A TRUE QUICK MOVING CLIPPER...WITH ITS BEST MOISTURE SUPPORT ALONG AND NORTH OF ITS PATH WHERE THE TIGHT MID- LEVEL THERMAL GRADIENT EXISTS. WHILE THERE IS FAIRLY STOUT 850-600 MB WAA AHEAD OF THIS FEATURE WED AFTERNOON AND EVENING...THE COLUMN LOOKS MUCH TOO DRY FOR PRECIP. SO ONLY HAVE POPS NEAR THE WI STATE LINE WITH THE ACTUAL LOW CENTER PASSAGE. THURSDAY NIGHT...WHAT HAD BEEN A DEEP SLOW-MOVING LOW IN THE LONGER RANGE FORECAST DAYS AGO HAS TRENDED TOWARDS A SHARP SOUTHEAST DIVING CLIPPER THAT STILL IS FAIRLY DEEP IN PRESSURE FOR CLIPPERS /~1002 MB/. THE PATH ON THE GFS AND EC FAVOR OUR AREA TO SEE SOME PRECIP...BUT EVEN A SLIGHT SHIFT NORTH OR SOUTH WOULD GREATLY REDUCE THEM AS IT IS A FAIRLY NARROW AXIS OF PRECIP WITH SUCH A STRUCTURE. INDEED THE 27.06 NAM IS A SOLUTION THAT IS FURTHER NORTH WITH LITTLE QPF. THE EC FOR TWO CONSECUTIVE RUNS HAS BEEN SLOWER THAN THE GFS...FAVORING OVERNIGHT THU AS OPPOSED TO THE EVE FOR INFLUENCE OVER OUR AREA. BOTH MODELS WOULD STILL SUPPORT SNOW CHANCES...BUT THE EC IS BETTER LOOKING FOR THAT WITH SLIGHTLY DEEPER HEIGHT FALLS AND GREATER MIXING RATIOS ON THE LIFTING SURFACES / 2.5-3 G/KG /. UNFORTUNATELY...THIS WAVE IS ONE OF MANY IN THE NORTHERN PACIFIC RIGHT NOW AND THUS NOT WELL SAMPLED. SO HAVE KEPT POPS ONLY AT A CHANCE BUT HAVE INCREASE VALUES. BEYOND...THE PROGRESSIVE PATTERN CONTINUES WITH AN IMMEDIATE INCREASE IN HEIGHTS AND A LOW-LEVEL THERMAL RIDGE INTO THE AREA. THE GFS...EC...AND GEM ALL BRING 850 MB TEMPERATURES TO ABOVE 8C ON SATURDAY. BIAS-CORRECTED FORECASTS FROM THESE MODELS BLENDED TOGETHER YIELDS HIGHS FROM THE UPPER 40S TO A STAGGERING MID 50S. WITH SUCH A QUICK TURNAROUND FROM COOL AIR ADVECTION BEHIND THE WAVE THURSDAY NIGHT/EARLY FRIDAY...WILL NOT BE GOING THAT HIGH. BUT HAVE BLENDED THE GOING FORECAST ALMOST 50 PERCENT WITH THESE. THIS AMPLIFIED PATTERN WHICH BRINGS IN THE WARMER REGIME IS AHEAD OF A DIGGING JET TO START THE NEW YEAR WHICH HAS BEEN HINTED AT IN SOLUTIONS FOR A WHILE. THIS WOULD AT LEAST BRING TEMPERATURES DOWN FOR EARLY NEXT WEEK...BUT CONFIDENCE IS LOW IN THIS AS WELL AS THE PRECIP CHANCES WITH THE SYSTEM EVOLVING ON THE JET UNDULATION. LOOKING INTO NEXT WEEK...DESPITE THE CHANCES FOR COOLER TEMPERATURES INITIALLY...THE 8 TO 14 DAY CPC OUTLOOK AND ESPECIALLY THE NAEFS MEMBERS FAVOR ABOVE NORMAL TEMPERATURES IN GENERAL. MTF && .AVIATION... //ORD AND MDW CONCERNS...UPDATED 20Z... * GUSTY NNW WINDS THIS AFTERNOON AND EVENING. * CIG TRENDS THROUGH THE DAY...TIMING LOW LEVEL MOISTURE CLEARING OUT THIS EVENING. * CHANCES FOR FLURRIES THIS AFTERNOON. BMD //DISCUSSION...UPDATED 18Z... COLD FRONT HAS SLID SOUTHEAST THROUGH THE FORECAST AREA WITH WINDS CHANGING TO THE NW/NNW BEHIND. UPSTREAM OBSERVATIONS SHOW DRY AIR AND GUSTY WINDS PUSHING SOUTHEAST BEHIND THE FRONT AND HELPING TO SCOUR OUT SOME OF THE LOW LEVEL MOISTURE. UPSTREAM STRATUS DECK/CIGS WHICH WERE MVFR HAVE GENERALLY IMPROVED TO VFR AND LENDS TO INCREASED CONFIDENCE THAT VFR CONDITIONS WILL PREVAIL ACROSS NORTHERN ILLINOIS THROUGH THE REMAINDER OF THE DAY. COLD ADVECTION INTO THE AREA WILL STEEPEN LOW LEVEL LAPSE RATES ALLOWING FOR DEEP MIXING THIS AFTERNOON. FORECAST SOUNDINGS CONTINUE TO INDICATE WIND GUSTS WILL INCREASE INTO THE UPPER 20KT RANGE WITH OCCASIONAL 30KT GUSTS NOT OUTSIDE THE REALM OF POSSIBILITY. VERY SHALLOW LOW LEVEL INSTABILITY IS ALSO INDICATED BY THE FORECAST SOUNDINGS AND CANNOT RULE OUT A FEW FLURRIES DEVELOPING THIS AFTERNOON...MAINLY IN THE 20Z-23Z WINDOW. SOME LIGHT RETURNS ARE ALREADY SHOWING UP ON RADAR ACROSS WEST/SOUTHWEST WISCONSIN LATE THIS MORNING. NO ACCUMULATIONS ARE EXPECTED...NOR ANY VIS RESTRICTIONS. LOW LEVEL MOISTURE WILL CONTINUE TO ERODE THROUGH THE EVENING AS SURFACE RIDGE BEGINS TO WORK IN FROM THE WEST. BY WEDNESDAY...WINDS WILL BEGIN TO BACK TO THE WEST AND WEAKEN AS HIGH PRESSURE BUILDS ACROSS THE REGION. BMD //ORD AND MDW CONFIDENCE...UPDATED 20Z... * HIGH CONFIDENCE ON WIND DIRECTION...MEDIUM CONFIDENCE ON SPEEDS/GUSTS AND TIMING. * MEDIUM CONFIDENCE IN FLURRIES THIS AFTERNOON...WITH NO IMPACTS TO VIS. HIGH CONFIDENCE IN NO ACCUMULATION. * MEDIUM CONFIDENCE IN CIG TRENDS. BMD //OUTLOOK FOR ORD/MDW FOR 00Z THURSDAY-12Z TUESDAY...UPDATED 12Z... * WEDNESDAY NIGHT...VFR. * THURSDAY...VFR. SLIGHT CHANCE OF LIGHT RAIN...POSSIBLY MIXING WITH LIGHT SNOW. * FRIDAY...MVFR POSSIBLE. SLIGHT CHANCE OF LIGHT RAIN OR LIGHT SNOW. * SATURDAY...VFR. * SUNDAY...SLIGHT CHANCE OF LIGHT RAIN OR LIGHT SNOW. * MONDAY...SLIGHT CHANCE OF LIGHT SNOW. PAW && .MARINE... 239 PM CST THE AREA OF LOW PRESSURE HAS MOVED OVER OHIO...BUT PRESSURE RISES AND A TIGHT PRESSURE GRADIENT BEHIND THE LOW HAS CAUSED WINDS TO STRENGTHEN THROUGHOUT THE DAY TODAY. GALES TO 45 KT ARE POSSIBLE THROUGH THE EARLY PART OF TONIGHT ACROSS THE ENTIRE LAKE. AS THE LOW MOVES NORTHWARD THROUGH THE NEW ENGLAND AREA TONIGHT...THE PRESSURE GRADIENT WILL WEAKEN AND WINDS WILL DIMINISH. HIGH PRESSURE ALSO MOVES IN BEHIND THE LOW ON WEDNESDAY...WHICH WILL ALSO HELP WINDS WEAKEN QUICKLY. WAVES ON THE OTHER HAND WILL REMAIN HIGH ESPECIALLY OVER THE SOUTHERN HALF OF THE LAKE AND IN THE NORTHERN INDIANA NEARSHORE ZONES THROUGH EARLY WEDNESDAY AFTERNOON. A WEAKENING CLIPPER SYSTEM WILL MOVE INTO NORTH DAKOTA WEDNESDAY NIGHT AND REACH LAKE MICHIGAN THURSDAY AFTERNOON. THE PRESSURE GRADIENT LOOKS VERY WEAK WITH THIS SYSTEM...THEREFORE NOT ANTICIPATING GALES. A WEAK RIDGE OF HIGH PRESSURES QUICKLY PASSES THROUGH REGION FRIDAY NIGHT INTO SATURDAY MORNING. THE PATTERN REMAINS ACTIVE THROUGH THE LONG TERM...WITH THE NEXT CHANCE FOR GALES LATE THIS WEEKEND INTO EARLY NEXT WEEK AS A LARGE LOW PRESSURE SYSTEM PASSES NORTH OF THE GREAT LAKES. JEE && .LOT WATCHES/WARNINGS/ADVISORIES... IL...NONE. IN...NONE. LM...GALE WARNING...LMZ080-LMZ261-LMZ362-LMZ364-LMZ366-LMZ563-LMZ565- LMZ567-LMZ669-LMZ671-LMZ673-LMZ675-LMZ744-LMZ745-LMZ777- LMZ779-LMZ868-LMZ870-LMZ872-LMZ874-LMZ876-LMZ878 UNTIL 3 AM WEDNESDAY. SMALL CRAFT ADVISORY...NEARSHORE WINTHROP HARBOR TO GARY IN UNTIL 6 PM WEDNESDAY. && $$
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
202 PM CST TUE DEC 27 2011 .DISCUSSION... 1240 PM CST FOR UPDATE... HAVE MADE FEW CHANGES TO GOING FORECAST...AND THOSE MAINLY ONLY TO END LINGERING PRECIP FROM THE WEST ACROSS THE FAR EAST/SOUTHEAST PART OF THE CWA THIS MORNING. HAVE ALSO TWEAKED HOURLY/MAX TEMPS JUST A BIT...WITH SEVERAL LOCATIONS HAVING TAGGED 40 DEGREES IN THE PAST HOUR OR TWO. MAIN NEAR TERM CONCERNS ARE POTENTIAL FOR A FEW FLURRIES OR SPRINKLES THIS AFTERNOON...AS WELL AS THE POTENTIAL FOR A LITTLE LIGHT LAKE EFFECT PRECIPITATION TO DEVELOP THIS AFTERNOON INTO THIS EVENING FOR NORTHWEST INDIANA. UPPER TROUGH CONTINUES TO DEEPEN THIS AFTERNOON AS VORT DIGS SOUTHEAST ACROSS THE MID-MISSISSIPPI VALLEY. IN THE LOW LEVELS... COLD ADVECTION BEGINNING TO STRENGTHEN WHICH WILL LEAD TO STEEPENING OF LOW LEVEL LAPSE RATES IN SHALLOW MOIST LAYER BELOW ABOUT 850 HPA. COMBINATION OF WEAK DPVA ALOFT AND WEAK LOW LEVEL INSTABILITY IN CYCLONIC LOW LEVEL FLOW IS EXPECTED TO SUPPORT POTENTIAL FOR A FEW FLURRIES OR SPRINKLES ACROSS THE AREA THROUGH THE AFTERNOON. REGIONAL RADAR MOSAIC INDEED SHOWS SOME VERY WEAK RETURNS MOVING SOUTH ACROSS PORTIONS OF EASTERN WI. FORECAST SOUNDINGS INDICATE TOP OF MOIST LAYER ROUGHLY -8 TO -10 C...SO EITHER P-TYPE OF --RA OR --S POSSIBLE. VORT AXIS SHIFTS EAST OF THE AREA EARLY THIS EVENING WITH DRYING AND SUBSIDENCE BRINGING AN END TO ANY LINGERING LIGHT PCPN. LAKE EFFECT POTENTIAL IS NOT OVERLY IMPRESSIVE...THOUGH PREVIOUSLY MENTIONED PROCESSES ARE EXPECTED TO GRADUALLY INCREASE LAKE TO 850 DELTA T VALUES TO 16/17 DEG/KM THIS EVENING. LOCAL HIGH-RES WRF DEPICTS A BRIEF PERIOD OF LOW LEVEL CONVERGENCE ALONG THE SOUTH SHORE OF THE LAKE EARLY THIS EVENING...BEFORE MOIST CONVERGENCE AXIS SHIFTS EAST OF PORTER COUNTY. LIGHT QPF OUTPUT OVER MAINLY NORTHERN PORTER COUNTY SUGGESTS A LITTLE MINOR ACCUMULATION POSSIBLE...BUT WINDOW WILL PROBABLY BE FAIRLY SHORT BETWEEN DEVELOPMENT OF BETTER LAKE-INDUCED LAPSE RATES AND BEST CONVERGENCE SHIFTING EAST. RATZER //PREV DISCUSSION... 330 AM CST THE FORECAST CHALLENGES ARE FIRST ON THE IMMEDIATE SHORT TERM WITH PRECIPITATION GRADUALLY SHIFTING EASTWARD THIS MORNING...THEN THE LAKE EFFECT SHOWER POTENTIAL INTO NORTHWEST INDIANA THIS AFTERNOON AND EVENING. THE ACTIVE FLOW PATTERN ACROSS THE NORTHERN U.S. AND SOME UNDULATIONS IN THIS INTO THE NEW YEAR KEEP THE FORECAST INTERESTING LOOKING FORWARD. SHORT TERM...LOW PRESSURE IS DEVELOPING FAIRLY RAPIDLY UNDER STRONG JET SUPPORT ACROSS WESTERN KY. MOIST ADVECTION ALOFT AND ASSOCIATED ASCENT CONTINUES TO WORK ITS WAY ACROSS NORTHWEST INDIANA. AN ELONGATED NORTHERN STREAM WAVE PUSHING EAST ACROSS THE REGION HAS INTERACTED WITH THIS...HELPING TO PRODUCE BANDS OF MODERATE PRECIP AT TIMES WHERE CONVERGENCE OF ECHOES WAS OBSERVED /AND LIKELY IMPLYING FRONTOGENETIC FORCING/. WITHIN THESE...A FEW REPORTS OF SLEET WERE OBSERVED/REPORTED OR ESTIMATED THROUGH UNKNOWN PRECIP AUTOMATED REPORTS. STRONGER FORCING LIFTING NORTH ACROSS EASTERN IL/WESTERN IN HAS HELPED TO LEAD TO EVAPORATIONAL COOLING SUPPORTING SNOW...AND BENTON COUNTY REPORTED A COATING OF SNOW ON THEIR PAVEMENT AS OF 300 AM. EXPECT THE AREAS RECEIVING PRECIPITATION AT DAYBREAK TO BE MAINLY A WET SNOW...WITH A LITTLE LIGHT RAIN POSSIBLY JUST BEFORE IT ENDS ON THE WESTERN PERIPHERY. THE SHIELD OF PRECIP WILL TAKE A WHILE TO EVOLVE EAST OUT OF THE AREA BASED ON THE QG FORCING ON THE RUC AS WELL AS WATER VAPOR TRENDS WITH THE DRY SLOT NOSE LIFTING INTO CENTRAL IN HELPING TO KEEP MAINLY SNOW GOING IN THE SOUTHEAST FORECAST AREA THIS MORNING. MAXIMUM ACCUMULATIONS NEAR AN INCH TOWARDS FOWLER AND RENSSALEAR STILL LOOK VALID. IN THE FAR SOUTH AND SOUTHEAST CHICAGO METRO WHILE SNOW MAY STILL BE OCCURRING THROUGH 9 AM OR SO...NO ACCUMULATION IS EXPECTED. THIS AFTERNOON...STRONG NORTH TO NORTHWEST WINDS IN THE WAKE OF THE SYSTEM ESTABLISH THEMSELVES DOWN THE FETCH OF LAKE MI THIS AFTERNOON. CONVERGENCE STREAMLINES FROM THE 27.06 NAM FAVOR A CORRIDOR OF SATURATED CONVERGENCE CENTERED ON MICHIGAN CITY...WITH SOME FURTHER WEST TOWARDS PORTER COUNTY. LAKE INDUCED EQUILIBRIUM LEVELS ARE PROJECTED OVER 5000 FT ON THE NAM FOR LATE THIS AFTERNOON AND EVENING AND THUS HAVE INCREASED POPS IN THAT AREA FOR SOME SNOW SHOWERS. FROM THIS...ONLY AN ADDITIONAL DUSTING IS EXPECTED WITH POTENTIAL FOR MORE JUST EAST OF THE FORECAST AREA. TONIGHT THROUGH THURSDAY...THE TEMPERATURES TONIGHT WILL BE A BATTLE BETWEEN THE COLD AND DRY AIR ADVECTION THIS EVENING AND THEN MID TO HIGH CLOUDS ON THE INCREASE FROM THE WEST OVERNIGHT WITH AN APPROACHING SHORT WAVE. IN ADDITION...LINGERING STRATOCU IN THE CAA REGIME IS LIKELY EARLY THIS EVENING...AND THAT MAY RESIDE THROUGH A GOOD PART OF THE NIGHT IN EASTERN AREAS. MODEL SPREAD REFLECTS THIS...VARYING UP TO TEN DEGREES IN SOME LOCATIONS. CONFIDENCE IS THUS MINIMAL ON TONIGHTS LOWS...AND AM NEAR THE CENTER OF THE SPREAD AT THIS TIME. A STRONGER SHORT WAVE ARRIVES INTO SOUTHERN WI ON LATE WEDNESDAY NIGHT INTO THURSDAY MORNING. THIS IS A TRUE QUICK MOVING CLIPPER...WITH ITS BEST MOISTURE SUPPORT ALONG AND NORTH OF ITS PATH WHERE THE TIGHT MID- LEVEL THERMAL GRADIENT EXISTS. WHILE THERE IS FAIRLY STOUT 850-600 MB WAA AHEAD OF THIS FEATURE WED AFTERNOON AND EVENING...THE COLUMN LOOKS MUCH TOO DRY FOR PRECIP. SO ONLY HAVE POPS NEAR THE WI STATE LINE WITH THE ACTUAL LOW CENTER PASSAGE. THURSDAY NIGHT...WHAT HAD BEEN A DEEP SLOW-MOVING LOW IN THE LONGER RANGE FORECAST DAYS AGO HAS TRENDED TOWARDS A SHARP SOUTHEAST DIVING CLIPPER THAT STILL IS FAIRLY DEEP IN PRESSURE FOR CLIPPERS /~1002 MB/. THE PATH ON THE GFS AND EC FAVOR OUR AREA TO SEE SOME PRECIP...BUT EVEN A SLIGHT SHIFT NORTH OR SOUTH WOULD GREATLY REDUCE THEM AS IT IS A FAIRLY NARROW AXIS OF PRECIP WITH SUCH A STRUCTURE. INDEED THE 27.06 NAM IS A SOLUTION THAT IS FURTHER NORTH WITH LITTLE QPF. THE EC FOR TWO CONSECUTIVE RUNS HAS BEEN SLOWER THAN THE GFS...FAVORING OVERNIGHT THU AS OPPOSED TO THE EVE FOR INFLUENCE OVER OUR AREA. BOTH MODELS WOULD STILL SUPPORT SNOW CHANCES...BUT THE EC IS BETTER LOOKING FOR THAT WITH SLIGHTLY DEEPER HEIGHT FALLS AND GREATER MIXING RATIOS ON THE LIFTING SURFACES / 2.5-3 G/KG /. UNFORTUNATELY...THIS WAVE IS ONE OF MANY IN THE NORTHERN PACIFIC RIGHT NOW AND THUS NOT WELL SAMPLED. SO HAVE KEPT POPS ONLY AT A CHANCE BUT HAVE INCREASE VALUES. BEYOND...THE PROGRESSIVE PATTERN CONTINUES WITH AN IMMEDIATE INCREASE IN HEIGHTS AND A LOW-LEVEL THERMAL RIDGE INTO THE AREA. THE GFS...EC...AND GEM ALL BRING 850 MB TEMPERATURES TO ABOVE 8C ON SATURDAY. BIAS-CORRECTED FORECASTS FROM THESE MODELS BLENDED TOGETHER YIELDS HIGHS FROM THE UPPER 40S TO A STAGGERING MID 50S. WITH SUCH A QUICK TURNAROUND FROM COOL AIR ADVECTION BEHIND THE WAVE THURSDAY NIGHT/EARLY FRIDAY...WILL NOT BE GOING THAT HIGH. BUT HAVE BLENDED THE GOING FORECAST ALMOST 50 PERCENT WITH THESE. THIS AMPLIFIED PATTERN WHICH BRINGS IN THE WARMER REGIME IS AHEAD OF A DIGGING JET TO START THE NEW YEAR WHICH HAS BEEN HINTED AT IN SOLUTIONS FOR A WHILE. THIS WOULD AT LEAST BRING TEMPERATURES DOWN FOR EARLY NEXT WEEK...BUT CONFIDENCE IS LOW IN THIS AS WELL AS THE PRECIP CHANCES WITH THE SYSTEM EVOLVING ON THE JET UNDULATION. LOOKING INTO NEXT WEEK...DESPITE THE CHANCES FOR COOLER TEMPERATURES INITIALLY...THE 8 TO 14 DAY CPC OUTLOOK AND ESPECIALLY THE NAEFS MEMBERS FAVOR ABOVE NORMAL TEMPERATURES IN GENERAL. MTF && .AVIATION... //ORD AND MDW CONCERNS...UPDATED 20Z... * GUSTY NNW WINDS THIS AFTERNOON AND EVENING. * CIG TRENDS THROUGH THE DAY...TIMING LOW LEVEL MOISTURE CLEARING OUT THIS EVENING. * CHANCES FOR FLURRIES THIS AFTERNOON. BMD //DISCUSSION...UPDATED 18Z... COLD FRONT HAS SLID SOUTHEAST THROUGH THE FORECAST AREA WITH WINDS CHANGING TO THE NW/NNW BEHIND. UPSTREAM OBSERVATIONS SHOW DRY AIR AND GUSTY WINDS PUSHING SOUTHEAST BEHIND THE FRONT AND HELPING TO SCOUR OUT SOME OF THE LOW LEVEL MOISTURE. UPSTREAM STRATUS DECK/CIGS WHICH WERE MVFR HAVE GENERALLY IMPROVED TO VFR AND LENDS TO INCREASED CONFIDENCE THAT VFR CONDITIONS WILL PREVAIL ACROSS NORTHERN ILLINOIS THROUGH THE REMAINDER OF THE DAY. COLD ADVECTION INTO THE AREA WILL STEEPEN LOW LEVEL LAPSE RATES ALLOWING FOR DEEP MIXING THIS AFTERNOON. FORECAST SOUNDINGS CONTINUE TO INDICATE WIND GUSTS WILL INCREASE INTO THE UPPER 20KT RANGE WITH OCCASIONAL 30KT GUSTS NOT OUTSIDE THE REALM OF POSSIBILITY. VERY SHALLOW LOW LEVEL INSTABILITY IS ALSO INDICATED BY THE FORECAST SOUNDINGS AND CANNOT RULE OUT A FEW FLURRIES DEVELOPING THIS AFTERNOON...MAINLY IN THE 20Z-23Z WINDOW. SOME LIGHT RETURNS ARE ALREADY SHOWING UP ON RADAR ACROSS WEST/SOUTHWEST WISCONSIN LATE THIS MORNING. NO ACCUMULATIONS ARE EXPECTED...NOR ANY VIS RESTRICTIONS. LOW LEVEL MOISTURE WILL CONTINUE TO ERODE THROUGH THE EVENING AS SURFACE RIDGE BEGINS TO WORK IN FROM THE WEST. BY WEDNESDAY...WINDS WILL BEGIN TO BACK TO THE WEST AND WEAKEN AS HIGH PRESSURE BUILDS ACROSS THE REGION. BMD //ORD AND MDW CONFIDENCE...UPDATED 20Z... * HIGH CONFIDENCE ON WIND DIRECTION...MEDIUM CONFIDENCE ON SPEEDS/GUSTS AND TIMING. * MEDIUM CONFIDENCE IN FLURRIES THIS AFTERNOON...WITH NO IMPACTS TO VIS. HIGH CONFIDENCE IN NO ACCUMULATION. * MEDIUM CONFIDENCE IN CIG TRENDS. BMD //OUTLOOK FOR ORD/MDW FOR 00Z THURSDAY-12Z TUESDAY...UPDATED 12Z... * WEDNESDAY NIGHT...VFR. * THURSDAY...VFR. SLIGHT CHANCE OF LIGHT RAIN...POSSIBLY MIXING WITH LIGHT SNOW. * FRIDAY...MVFR POSSIBLE. SLIGHT CHANCE OF LIGHT RAIN OR LIGHT SNOW. * SATURDAY...VFR. * SUNDAY...SLIGHT CHANCE OF LIGHT RAIN OR LIGHT SNOW. * MONDAY...SLIGHT CHANCE OF LIGHT SNOW. PAW && .MARINE... 235 AM CST AN AREA OF LOW PRESSURE CONTINUES TO SLOWLY MOVE EAST ACROSS SOUTHERN ONTARIO THIS MORNING. DRAPED SOUTH FROM THIS LOW AND SPANNING MUCH OF THE UPPER AND MIDDLE MISSISSIPPI VALLEY IS A COLD FRONT THAT WILL SLIDE ACROSS THE LAKE LATER THIS MORNING. AHEAD OF IT...THE 15 TO 25 KT WINDS WILL VEER TO THE WEST AND THEN TO THE NORTHWEST THROUGH THE EARLY AFTERNOON HOURS. THE STRONGEST SURGE OF COLD AIR IS NOT ANTICIPATED TO BE UNTIL THE LATER AFTERNOON HOURS FOR THE NORTHERN HALF OF THE LAKE...AND SHORTLY THEREAFTER FOR THE SOUTHERN HALF. IT IS WITH THIS SURGE THAT THE STRONGEST OF WINDS IS ANTICIPATED. HIGH END GALES ARE AGAIN LIKELY...BUT FOR THE ENTIRE SPAN OF THE LAKE WITH THIS EVENT AS OPPOSED TO THE STRONGEST WINDS REMAINING NORTH YESTERDAY. FORECAST SOUNDINGS ARE ALSO INDICATING THE POTENTIAL FOR LOW END STORM FORCE GUSTS. FEEL THAT THE MAJORITY OF THE WINDS WILL REMAIN BELOW STORM CRITERIA FOR THE OPEN WATERS AND WILL ONLY MENTION IN AN OCCASIONAL GROUP. THOUGHTS THEN TURN TO NEARSHORE BURNS HARBOR TO MICHIGAN CITY IN AND 744...AND POTENTIALLY 743 AND GALES. WITH THE STRONG NORTHWESTERLY WINDS EXPECTED...INCREASES THE CHANCES INTO THE EVENING HOURS AND OVERNIGHT. WILL ERR ON THE SIDE OF CAUTION FOR THE FRICTIONLESS MARINE LOCATIONS AND CANCEL THE SMALL CRAFT FOR THOSE LOCATIONS AND HOIST A GALE WARNING. CONDITIONS SET TO IMPROVE LATE TONIGHT AS RIDGING ACROSS THE SURFACE BUILDS...THOUGH PROLONGED STRONG SOUTHWESTERLY FLOW WILL SLOWLY RAMP UP THROUGH WEDNESDAY NIGHT...WITH FLOW PROGGED TO REMAIN BELOW GALE. SHEA && .LOT WATCHES/WARNINGS/ADVISORIES... IL...NONE. IN...NONE. LM...GALE WARNING...LMZ080-LMZ261-LMZ362-LMZ364-LMZ366-LMZ563-LMZ565- LMZ567-LMZ669-LMZ671-LMZ673-LMZ675-LMZ744-LMZ745-LMZ777- LMZ779-LMZ868-LMZ870-LMZ872-LMZ874-LMZ876-LMZ878 UNTIL 3 AM WEDNESDAY. SMALL CRAFT ADVISORY...NEARSHORE WINTHROP HARBOR TO GARY IN UNTIL 6 PM WEDNESDAY. && $$
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
1240 PM CST TUE DEC 27 2011 .DISCUSSION... 1240 PM CST FOR UPDATE... HAVE MADE FEW CHANGES TO GOING FORECAST...AND THOSE MAINLY ONLY TO END LINGERING PRECIP FROM THE WEST ACROSS THE FAR EAST/SOUTHEAST PART OF THE CWA THIS MORNING. HAVE ALSO TWEAKED HOURLY/MAX TEMPS JUST A BIT...WITH SEVERAL LOCATIONS HAVING TAGGED 40 DEGREES IN THE PAST HOUR OR TWO. MAIN NEAR TERM CONCERNS ARE POTENTIAL FOR A FEW FLURRIES OR SPRINKLES THIS AFTERNOON...AS WELL AS THE POTENTIAL FOR A LITTLE LIGHT LAKE EFFECT PRECIPITATION TO DEVELOP THIS AFTERNOON INTO THIS EVENING FOR NORTHWEST INDIANA. UPPER TROUGH CONTINUES TO DEEPEN THIS AFTERNOON AS VORT DIGS SOUTHEAST ACROSS THE MID-MISSISSIPPI VALLEY. IN THE LOW LEVELS... COLD ADVECTION BEGINNING TO STRENGTHEN WHICH WILL LEAD TO STEEPENING OF LOW LEVEL LAPSE RATES IN SHALLOW MOIST LAYER BELOW ABOUT 850 HPA. COMBINATION OF WEAK DPVA ALOFT AND WEAK LOW LEVEL INSTABILITY IN CYCLONIC LOW LEVEL FLOW IS EXPECTED TO SUPPORT POTENTIAL FOR A FEW FLURRIES OR SPRINKLES ACROSS THE AREA THROUGH THE AFTERNOON. REGIONAL RADAR MOSAIC INDEED SHOWS SOME VERY WEAK RETURNS MOVING SOUTH ACROSS PORTIONS OF EASTERN WI. FORECAST SOUNDINGS INDICATE TOP OF MOIST LAYER ROUGHLY -8 TO -10 C...SO EITHER P-TYPE OF --RA OR --S POSSIBLE. VORT AXIS SHIFTS EAST OF THE AREA EARLY THIS EVENING WITH DRYING AND SUBSIDENCE BRINGING AN END TO ANY LINGERING LIGHT PCPN. LAKE EFFECT POTENTIAL IS NOT OVERLY IMPRESSIVE...THOUGH PREVIOUSLY MENTIONED PROCESSES ARE EXPECTED TO GRADUALLY INCREASE LAKE TO 850 DELTA T VALUES TO 16/17 DEG/KM THIS EVENING. LOCAL HIGH-RES WRF DEPICTS A BRIEF PERIOD OF LOW LEVEL CONVERGENCE ALONG THE SOUTH SHORE OF THE LAKE EARLY THIS EVENING...BEFORE MOIST CONVERGENCE AXIS SHIFTS EAST OF PORTER COUNTY. LIGHT QPF OUTPUT OVER MAINLY NORTHERN PORTER COUNTY SUGGESTS A LITTLE MINOR ACCUMULATION POSSIBLE...BUT WINDOW WILL PROBABLY BE FAIRLY SHORT BETWEEN DEVELOPMENT OF BETTER LAKE-INDUCED LAPSE RATES AND BEST CONVERGENCE SHIFTING EAST. RATZER && .PREV DISCUSSION... 330 AM CST THE FORECAST CHALLENGES ARE FIRST ON THE IMMEDIATE SHORT TERM WITH PRECIPITATION GRADUALLY SHIFTING EASTWARD THIS MORNING...THEN THE LAKE EFFECT SHOWER POTENTIAL INTO NORTHWEST INDIANA THIS AFTERNOON AND EVENING. THE ACTIVE FLOW PATTERN ACROSS THE NORTHERN U.S. AND SOME UNDULATIONS IN THIS INTO THE NEW YEAR KEEP THE FORECAST INTERESTING LOOKING FORWARD. SHORT TERM...LOW PRESSURE IS DEVELOPING FAIRLY RAPIDLY UNDER STRONG JET SUPPORT ACROSS WESTERN KY. MOIST ADVECTION ALOFT AND ASSOCIATED ASCENT CONTINUES TO WORK ITS WAY ACROSS NORTHWEST INDIANA. AN ELONGATED NORTHERN STREAM WAVE PUSHING EAST ACROSS THE REGION HAS INTERACTED WITH THIS...HELPING TO PRODUCE BANDS OF MODERATE PRECIP AT TIMES WHERE CONVERGENCE OF ECHOES WAS OBSERVED /AND LIKELY IMPLYING FRONTOGENETIC FORCING/. WITHIN THESE...A FEW REPORTS OF SLEET WERE OBSERVED/REPORTED OR ESTIMATED THROUGH UNKNOWN PRECIP AUTOMATED REPORTS. STRONGER FORCING LIFTING NORTH ACROSS EASTERN IL/WESTERN IN HAS HELPED TO LEAD TO EVAPORATIONAL COOLING SUPPORTING SNOW...AND BENTON COUNTY REPORTED A COATING OF SNOW ON THEIR PAVEMENT AS OF 300 AM. EXPECT THE AREAS RECEIVING PRECIPITATION AT DAYBREAK TO BE MAINLY A WET SNOW...WITH A LITTLE LIGHT RAIN POSSIBLY JUST BEFORE IT ENDS ON THE WESTERN PERIPHERY. THE SHIELD OF PRECIP WILL TAKE A WHILE TO EVOLVE EAST OUT OF THE AREA BASED ON THE QG FORCING ON THE RUC AS WELL AS WATER VAPOR TRENDS WITH THE DRY SLOT NOSE LIFTING INTO CENTRAL IN HELPING TO KEEP MAINLY SNOW GOING IN THE SOUTHEAST FORECAST AREA THIS MORNING. MAXIMUM ACCUMULATIONS NEAR AN INCH TOWARDS FOWLER AND RENSSALEAR STILL LOOK VALID. IN THE FAR SOUTH AND SOUTHEAST CHICAGO METRO WHILE SNOW MAY STILL BE OCCURRING THROUGH 9 AM OR SO...NO ACCUMULATION IS EXPECTED. THIS AFTERNOON...STRONG NORTH TO NORTHWEST WINDS IN THE WAKE OF THE SYSTEM ESTABLISH THEMSELVES DOWN THE FETCH OF LAKE MI THIS AFTERNOON. CONVERGENCE STREAMLINES FROM THE 27.06 NAM FAVOR A CORRIDOR OF SATURATED CONVERGENCE CENTERED ON MICHIGAN CITY...WITH SOME FURTHER WEST TOWARDS PORTER COUNTY. LAKE INDUCED EQUILIBRIUM LEVELS ARE PROJECTED OVER 5000 FT ON THE NAM FOR LATE THIS AFTERNOON AND EVENING AND THUS HAVE INCREASED POPS IN THAT AREA FOR SOME SNOW SHOWERS. FROM THIS...ONLY AN ADDITIONAL DUSTING IS EXPECTED WITH POTENTIAL FOR MORE JUST EAST OF THE FORECAST AREA. TONIGHT THROUGH THURSDAY...THE TEMPERATURES TONIGHT WILL BE A BATTLE BETWEEN THE COLD AND DRY AIR ADVECTION THIS EVENING AND THEN MID TO HIGH CLOUDS ON THE INCREASE FROM THE WEST OVERNIGHT WITH AN APPROACHING SHORT WAVE. IN ADDITION...LINGERING STRATOCU IN THE CAA REGIME IS LIKELY EARLY THIS EVENING...AND THAT MAY RESIDE THROUGH A GOOD PART OF THE NIGHT IN EASTERN AREAS. MODEL SPREAD REFLECTS THIS...VARYING UP TO TEN DEGREES IN SOME LOCATIONS. CONFIDENCE IS THUS MINIMAL ON TONIGHTS LOWS...AND AM NEAR THE CENTER OF THE SPREAD AT THIS TIME. A STRONGER SHORT WAVE ARRIVES INTO SOUTHERN WI ON LATE WEDNESDAY NIGHT INTO THURSDAY MORNING. THIS IS A TRUE QUICK MOVING CLIPPER...WITH ITS BEST MOISTURE SUPPORT ALONG AND NORTH OF ITS PATH WHERE THE TIGHT MID- LEVEL THERMAL GRADIENT EXISTS. WHILE THERE IS FAIRLY STOUT 850-600 MB WAA AHEAD OF THIS FEATURE WED AFTERNOON AND EVENING...THE COLUMN LOOKS MUCH TOO DRY FOR PRECIP. SO ONLY HAVE POPS NEAR THE WI STATE LINE WITH THE ACTUAL LOW CENTER PASSAGE. THURSDAY NIGHT...WHAT HAD BEEN A DEEP SLOW-MOVING LOW IN THE LONGER RANGE FORECAST DAYS AGO HAS TRENDED TOWARDS A SHARP SOUTHEAST DIVING CLIPPER THAT STILL IS FAIRLY DEEP IN PRESSURE FOR CLIPPERS /~1002 MB/. THE PATH ON THE GFS AND EC FAVOR OUR AREA TO SEE SOME PRECIP...BUT EVEN A SLIGHT SHIFT NORTH OR SOUTH WOULD GREATLY REDUCE THEM AS IT IS A FAIRLY NARROW AXIS OF PRECIP WITH SUCH A STRUCTURE. INDEED THE 27.06 NAM IS A SOLUTION THAT IS FURTHER NORTH WITH LITTLE QPF. THE EC FOR TWO CONSECUTIVE RUNS HAS BEEN SLOWER THAN THE GFS...FAVORING OVERNIGHT THU AS OPPOSED TO THE EVE FOR INFLUENCE OVER OUR AREA. BOTH MODELS WOULD STILL SUPPORT SNOW CHANCES...BUT THE EC IS BETTER LOOKING FOR THAT WITH SLIGHTLY DEEPER HEIGHT FALLS AND GREATER MIXING RATIOS ON THE LIFTING SURFACES / 2.5-3 G/KG /. UNFORTUNATELY...THIS WAVE IS ONE OF MANY IN THE NORTHERN PACIFIC RIGHT NOW AND THUS NOT WELL SAMPLED. SO HAVE KEPT POPS ONLY AT A CHANCE BUT HAVE INCREASE VALUES. BEYOND...THE PROGRESSIVE PATTERN CONTINUES WITH AN IMMEDIATE INCREASE IN HEIGHTS AND A LOW-LEVEL THERMAL RIDGE INTO THE AREA. THE GFS...EC...AND GEM ALL BRING 850 MB TEMPERATURES TO ABOVE 8C ON SATURDAY. BIAS-CORRECTED FORECASTS FROM THESE MODELS BLENDED TOGETHER YIELDS HIGHS FROM THE UPPER 40S TO A STAGGERING MID 50S. WITH SUCH A QUICK TURNAROUND FROM COOL AIR ADVECTION BEHIND THE WAVE THURSDAY NIGHT/EARLY FRIDAY...WILL NOT BE GOING THAT HIGH. BUT HAVE BLENDED THE GOING FORECAST ALMOST 50 PERCENT WITH THESE. THIS AMPLIFIED PATTERN WHICH BRINGS IN THE WARMER REGIME IS AHEAD OF A DIGGING JET TO START THE NEW YEAR WHICH HAS BEEN HINTED AT IN SOLUTIONS FOR A WHILE. THIS WOULD AT LEAST BRING TEMPERATURES DOWN FOR EARLY NEXT WEEK...BUT CONFIDENCE IS LOW IN THIS AS WELL AS THE PRECIP CHANCES WITH THE SYSTEM EVOLVING ON THE JET UNDULATION. LOOKING INTO NEXT WEEK...DESPITE THE CHANCES FOR COOLER TEMPERATURES INITIALLY...THE 8 TO 14 DAY CPC OUTLOOK AND ESPECIALLY THE NAEFS MEMBERS FAVOR ABOVE NORMAL TEMPERATURES IN GENERAL. MTF && .AVIATION... //ORD AND MDW CONCERNS...UPDATED 18Z... * GUSTY NNW WINDS THIS AFTERNOON AND EVENING. * CIGS TRENDS THROUGH THE DAY...TIMING LOW LEVEL MOISTURE CLEARING OUT LATE THIS EVENING. * CHANCES FOR FLURRIES THIS AFTERNOON. BMD //DISCUSSION...UPDATED 18Z... COLD FRONT HAS SLID SOUTHEAST THROUGH THE FORECAST AREA WITH WINDS CHANGING TO THE NW/NNW BEHIND. UPSTREAM OBSERVATIONS SHOW DRY AIR AND GUSTY WINDS PUSHING SOUTHEAST BEHIND THE FRONT AND HELPING TO SCOUR OUT SOME OF THE LOW LEVEL MOISTURE. UPSTREAM STRATUS DECK/CIGS WHICH WERE MVFR HAVE GENERALLY IMPROVED TO VFR AND LENDS TO INCREASED CONFIDENCE THAT VFR CONDITIONS WILL PREVAIL ACROSS NORTHERN ILLINOIS THROUGH THE REMAINDER OF THE DAY. COLD ADVECTION INTO THE AREA WILL STEEPEN LOW LEVEL LAPSE RATES ALLOWING FOR DEEP MIXING THIS AFTERNOON. FORECAST SOUNDINGS CONTINUE TO INDICATE WIND GUSTS WILL INCREASE INTO THE UPPER 20KT RANGE WITH OCCASIONAL 30KT GUSTS NOT OUTSIDE THE REALM OF POSSIBILITY. VERY SHALLOW LOW LEVEL INSTABILITY IS ALSO INDICATED BY THE FORECAST SOUNDINGS AND CANNOT RULE OUT A FEW FLURRIES DEVELOPING THIS AFTERNOON...MAINLY IN THE 20Z-23Z WINDOW. SOME LIGHT RETURNS ARE ALREADY SHOWING UP ON RADAR ACROSS WEST/SOUTHWEST WISCONSIN LATE THIS MORNING. NO ACCUMULATIONS ARE EXPECTED...NOR ANY VIS RESTRICTIONS. LOW LEVEL MOISTURE WILL CONTINUE TO ERODE THROUGH THE EVENING AS SURFACE RIDGE BEGINS TO WORK IN FROM THE WEST. BY WEDNESDAY...WINDS WILL BEGIN TO BACK TO THE WEST AND WEAKEN AS HIGH PRESSURE BUILDS ACROSS THE REGION. BMD //ORD AND MDW CONFIDENCE...UPDATED 18Z... * MEDIUM TO HIGH CONFIDENCE IN VFR CONDITIONS THROUGH THE PERIOD. * HIGH CONFIDENCE ON WIND DIRECTION...MEDIUM CONFIDENCE ON SPEEDS/GUSTS AND TIMING. * MEDIUM CONFIDENCE IN FLURRIES THIS AFTERNOON...WITH NO IMPACTS TO VIS. HIGH CONFIDENCE IN NO ACCUMULATION. BMD //OUTLOOK FOR ORD/MDW FOR 00Z THURSDAY-12Z TUESDAY...UPDATED 12Z... * WEDNESDAY NIGHT...VFR. * THURSDAY...VFR. SLIGHT CHANCE OF LIGHT RAIN...POSSIBLY MIXING WITH LIGHT SNOW. * FRIDAY...MVFR POSSIBLE. SLIGHT CHANCE OF LIGHT RAIN OR LIGHT SNOW. * SATURDAY...VFR. * SUNDAY...SLIGHT CHANCE OF LIGHT RAIN OR LIGHT SNOW. * MONDAY...SLIGHT CHANCE OF LIGHT SNOW. PAW && .MARINE... 235 AM CST AN AREA OF LOW PRESSURE CONTINUES TO SLOWLY MOVE EAST ACROSS SOUTHERN ONTARIO THIS MORNING. DRAPED SOUTH FROM THIS LOW AND SPANNING MUCH OF THE UPPER AND MIDDLE MISSISSIPPI VALLEY IS A COLD FRONT THAT WILL SLIDE ACROSS THE LAKE LATER THIS MORNING. AHEAD OF IT...THE 15 TO 25 KT WINDS WILL VEER TO THE WEST AND THEN TO THE NORTHWEST THROUGH THE EARLY AFTERNOON HOURS. THE STRONGEST SURGE OF COLD AIR IS NOT ANTICIPATED TO BE UNTIL THE LATER AFTERNOON HOURS FOR THE NORTHERN HALF OF THE LAKE...AND SHORTLY THEREAFTER FOR THE SOUTHERN HALF. IT IS WITH THIS SURGE THAT THE STRONGEST OF WINDS IS ANTICIPATED. HIGH END GALES ARE AGAIN LIKELY...BUT FOR THE ENTIRE SPAN OF THE LAKE WITH THIS EVENT AS OPPOSED TO THE STRONGEST WINDS REMAINING NORTH YESTERDAY. FORECAST SOUNDINGS ARE ALSO INDICATING THE POTENTIAL FOR LOW END STORM FORCE GUSTS. FEEL THAT THE MAJORITY OF THE WINDS WILL REMAIN BELOW STORM CRITERIA FOR THE OPEN WATERS AND WILL ONLY MENTION IN AN OCCASIONAL GROUP. THOUGHTS THEN TURN TO NEARSHORE BURNS HARBOR TO MICHIGAN CITY IN AND 744...AND POTENTIALLY 743 AND GALES. WITH THE STRONG NORTHWESTERLY WINDS EXPECTED...INCREASES THE CHANCES INTO THE EVENING HOURS AND OVERNIGHT. WILL ERR ON THE SIDE OF CAUTION FOR THE FRICTIONLESS MARINE LOCATIONS AND CANCEL THE SMALL CRAFT FOR THOSE LOCATIONS AND HOIST A GALE WARNING. CONDITIONS SET TO IMPROVE LATE TONIGHT AS RIDGING ACROSS THE SURFACE BUILDS...THOUGH PROLONGED STRONG SOUTHWESTERLY FLOW WILL SLOWLY RAMP UP THROUGH WEDNESDAY NIGHT...WITH FLOW PROGGED TO REMAIN BELOW GALE. SHEA && .LOT WATCHES/WARNINGS/ADVISORIES... IL...NONE. IN...NONE. LM...GALE WARNING...LMZ080-LMZ261-LMZ362-LMZ364-LMZ366-LMZ563-LMZ565- LMZ567-LMZ669-LMZ671-LMZ673-LMZ675-LMZ744-LMZ745-LMZ777- LMZ779-LMZ868-LMZ870-LMZ872-LMZ874-LMZ876-LMZ878 UNTIL 3 AM WEDNESDAY. SMALL CRAFT ADVISORY...NEARSHORE WINTHROP HARBOR TO GARY IN UNTIL 6 PM WEDNESDAY. && $$
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
1141 AM CST TUE DEC 27 2011 .DISCUSSION... 330 AM CST THE FORECAST CHALLENGES ARE FIRST ON THE IMMEDIATE SHORT TERM WITH PRECIPITATION GRADUALLY SHIFTING EASTWARD THIS MORNING...THEN THE LAKE EFFECT SHOWER POTENTIAL INTO NORTHWEST INDIANA THIS AFTERNOON AND EVENING. THE ACTIVE FLOW PATTERN ACROSS THE NORTHERN U.S. AND SOME UNDULATIONS IN THIS INTO THE NEW YEAR KEEP THE FORECAST INTERESTING LOOKING FORWARD. SHORT TERM...LOW PRESSURE IS DEVELOPING FAIRLY RAPIDLY UNDER STRONG JET SUPPORT ACROSS WESTERN KY. MOIST ADVECTION ALOFT AND ASSOCIATED ASCENT CONTINUES TO WORK ITS WAY ACROSS NORTHWEST INDIANA. AN ELONGATED NORTHERN STREAM WAVE PUSHING EAST ACROSS THE REGION HAS INTERACTED WITH THIS...HELPING TO PRODUCE BANDS OF MODERATE PRECIP AT TIMES WHERE CONVERGENCE OF ECHOES WAS OBSERVED /AND LIKELY IMPLYING FRONTOGENETIC FORCING/. WITHIN THESE...A FEW REPORTS OF SLEET WERE OBSERVED/REPORTED OR ESTIMATED THROUGH UNKNOWN PRECIP AUTOMATED REPORTS. STRONGER FORCING LIFTING NORTH ACROSS EASTERN IL/WESTERN IN HAS HELPED TO LEAD TO EVAPORATIONAL COOLING SUPPORTING SNOW...AND BENTON COUNTY REPORTED A COATING OF SNOW ON THEIR PAVEMENT AS OF 300 AM. EXPECT THE AREAS RECEIVING PRECIPITATION AT DAYBREAK TO BE MAINLY A WET SNOW...WITH A LITTLE LIGHT RAIN POSSIBLY JUST BEFORE IT ENDS ON THE WESTERN PERIPHERY. THE SHIELD OF PRECIP WILL TAKE A WHILE TO EVOLVE EAST OUT OF THE AREA BASED ON THE QG FORCING ON THE RUC AS WELL AS WATER VAPOR TRENDS WITH THE DRY SLOT NOSE LIFTING INTO CENTRAL IN HELPING TO KEEP MAINLY SNOW GOING IN THE SOUTHEAST FORECAST AREA THIS MORNING. MAXIMUM ACCUMULATIONS NEAR AN INCH TOWARDS FOWLER AND RENSSALEAR STILL LOOK VALID. IN THE FAR SOUTH AND SOUTHEAST CHICAGO METRO WHILE SNOW MAY STILL BE OCCURRING THROUGH 9 AM OR SO...NO ACCUMULATION IS EXPECTED. THIS AFTERNOON...STRONG NORTH TO NORTHWEST WINDS IN THE WAKE OF THE SYSTEM ESTABLISH THEMSELVES DOWN THE FETCH OF LAKE MI THIS AFTERNOON. CONVERGENCE STREAMLINES FROM THE 27.06 NAM FAVOR A CORRIDOR OF SATURATED CONVERGENCE CENTERED ON MICHIGAN CITY...WITH SOME FURTHER WEST TOWARDS PORTER COUNTY. LAKE INDUCED EQUILIBRIUM LEVELS ARE PROJECTED OVER 5000 FT ON THE NAM FOR LATE THIS AFTERNOON AND EVENING AND THUS HAVE INCREASED POPS IN THAT AREA FOR SOME SNOW SHOWERS. FROM THIS...ONLY AN ADDITIONAL DUSTING IS EXPECTED WITH POTENTIAL FOR MORE JUST EAST OF THE FORECAST AREA. TONIGHT THROUGH THURSDAY...THE TEMPERATURES TONIGHT WILL BE A BATTLE BETWEEN THE COLD AND DRY AIR ADVECTION THIS EVENING AND THEN MID TO HIGH CLOUDS ON THE INCREASE FROM THE WEST OVERNIGHT WITH AN APPROACHING SHORT WAVE. IN ADDITION...LINGERING STRATOCU IN THE CAA REGIME IS LIKELY EARLY THIS EVENING...AND THAT MAY RESIDE THROUGH A GOOD PART OF THE NIGHT IN EASTERN AREAS. MODEL SPREAD REFLECTS THIS...VARYING UP TO TEN DEGREES IN SOME LOCATIONS. CONFIDENCE IS THUS MINIMAL ON TONIGHTS LOWS...AND AM NEAR THE CENTER OF THE SPREAD AT THIS TIME. A STRONGER SHORT WAVE ARRIVES INTO SOUTHERN WI ON LATE WEDNESDAY NIGHT INTO THURSDAY MORNING. THIS IS A TRUE QUICK MOVING CLIPPER...WITH ITS BEST MOISTURE SUPPORT ALONG AND NORTH OF ITS PATH WHERE THE TIGHT MID- LEVEL THERMAL GRADIENT EXISTS. WHILE THERE IS FAIRLY STOUT 850-600 MB WAA AHEAD OF THIS FEATURE WED AFTERNOON AND EVENING...THE COLUMN LOOKS MUCH TOO DRY FOR PRECIP. SO ONLY HAVE POPS NEAR THE WI STATE LINE WITH THE ACTUAL LOW CENTER PASSAGE. THURSDAY NIGHT...WHAT HAD BEEN A DEEP SLOW-MOVING LOW IN THE LONGER RANGE FORECAST DAYS AGO HAS TRENDED TOWARDS A SHARP SOUTHEAST DIVING CLIPPER THAT STILL IS FAIRLY DEEP IN PRESSURE FOR CLIPPERS /~1002 MB/. THE PATH ON THE GFS AND EC FAVOR OUR AREA TO SEE SOME PRECIP...BUT EVEN A SLIGHT SHIFT NORTH OR SOUTH WOULD GREATLY REDUCE THEM AS IT IS A FAIRLY NARROW AXIS OF PRECIP WITH SUCH A STRUCTURE. INDEED THE 27.06 NAM IS A SOLUTION THAT IS FURTHER NORTH WITH LITTLE QPF. THE EC FOR TWO CONSECUTIVE RUNS HAS BEEN SLOWER THAN THE GFS...FAVORING OVERNIGHT THU AS OPPOSED TO THE EVE FOR INFLUENCE OVER OUR AREA. BOTH MODELS WOULD STILL SUPPORT SNOW CHANCES...BUT THE EC IS BETTER LOOKING FOR THAT WITH SLIGHTLY DEEPER HEIGHT FALLS AND GREATER MIXING RATIOS ON THE LIFTING SURFACES / 2.5-3 G/KG /. UNFORTUNATELY...THIS WAVE IS ONE OF MANY IN THE NORTHERN PACIFIC RIGHT NOW AND THUS NOT WELL SAMPLED. SO HAVE KEPT POPS ONLY AT A CHANCE BUT HAVE INCREASE VALUES. BEYOND...THE PROGRESSIVE PATTERN CONTINUES WITH AN IMMEDIATE INCREASE IN HEIGHTS AND A LOW-LEVEL THERMAL RIDGE INTO THE AREA. THE GFS...EC...AND GEM ALL BRING 850 MB TEMPERATURES TO ABOVE 8C ON SATURDAY. BIAS-CORRECTED FORECASTS FROM THESE MODELS BLENDED TOGETHER YIELDS HIGHS FROM THE UPPER 40S TO A STAGGERING MID 50S. WITH SUCH A QUICK TURNAROUND FROM COOL AIR ADVECTION BEHIND THE WAVE THURSDAY NIGHT/EARLY FRIDAY...WILL NOT BE GOING THAT HIGH. BUT HAVE BLENDED THE GOING FORECAST ALMOST 50 PERCENT WITH THESE. THIS AMPLIFIED PATTERN WHICH BRINGS IN THE WARMER REGIME IS AHEAD OF A DIGGING JET TO START THE NEW YEAR WHICH HAS BEEN HINTED AT IN SOLUTIONS FOR A WHILE. THIS WOULD AT LEAST BRING TEMPERATURES DOWN FOR EARLY NEXT WEEK...BUT CONFIDENCE IS LOW IN THIS AS WELL AS THE PRECIP CHANCES WITH THE SYSTEM EVOLVING ON THE JET UNDULATION. LOOKING INTO NEXT WEEK...DESPITE THE CHANCES FOR COOLER TEMPERATURES INITIALLY...THE 8 TO 14 DAY CPC OUTLOOK AND ESPECIALLY THE NAEFS MEMBERS FAVOR ABOVE NORMAL TEMPERATURES IN GENERAL. MTF && .AVIATION... //ORD AND MDW CONCERNS...UPDATED 18Z... * GUSTY NNW WINDS THIS AFTERNOON AND EVENING. * CIGS TRENDS THROUGH THE DAY...TIMING LOW LEVEL MOISTURE CLEARING OUT LATE THIS EVENING. * CHANCES FOR FLURRIES THIS AFTERNOON. BMD //DISCUSSION...UPDATED 18Z... COLD FRONT HAS SLID SOUTHEAST THROUGH THE FORECAST AREA WITH WINDS CHANGING TO THE NW/NNW BEHIND. UPSTREAM OBSERVATIONS SHOW DRY AIR AND GUSTY WINDS PUSHING SOUTHEAST BEHIND THE FRONT AND HELPING TO SCOUR OUT SOME OF THE LOW LEVEL MOISTURE. UPSTREAM STRATUS DECK/CIGS WHICH WERE MVFR HAVE GENERALLY IMPROVED TO VFR AND LENDS TO INCREASED CONFIDENCE THAT VFR CONDITIONS WILL PREVAIL ACROSS NORTHERN ILLINOIS THROUGH THE REMAINDER OF THE DAY. COLD ADVECTION INTO THE AREA WILL STEEPEN LOW LEVEL LAPSE RATES ALLOWING FOR DEEP MIXING THIS AFTERNOON. FORECAST SOUNDINGS CONTINUE TO INDICATE WIND GUSTS WILL INCREASE INTO THE UPPER 20KT RANGE WITH OCCASIONAL 30KT GUSTS NOT OUTSIDE THE REALM OF POSSIBILITY. VERY SHALLOW LOW LEVEL INSTABILITY IS ALSO INDICATED BY THE FORECAST SOUNDINGS AND CANNOT RULE OUT A FEW FLURRIES DEVELOPING THIS AFTERNOON...MAINLY IN THE 20Z-23Z WINDOW. SOME LIGHT RETURNS ARE ALREADY SHOWING UP ON RADAR ACROSS WEST/SOUTHWEST WISCONSIN LATE THIS MORNING. NO ACCUMULATIONS ARE EXPECTED...NOR ANY VIS RESTRICTIONS. LOW LEVEL MOISTURE WILL CONTINUE TO ERODE THROUGH THE EVENING AS SURFACE RIDGE BEGINS TO WORK IN FROM THE WEST. BY WEDNESDAY...WINDS WILL BEGIN TO BACK TO THE WEST AND WEAKEN AS HIGH PRESSURE BUILDS ACROSS THE REGION. BMD //ORD AND MDW CONFIDENCE...UPDATED 18Z... * MEDIUM TO HIGH CONFIDENCE IN VFR CONDITIONS THROUGH THE PERIOD. * HIGH CONFIDENCE ON WIND DIRECTION...MEDIUM CONFIDENCE ON SPEEDS/GUSTS AND TIMING. * MEDIUM CONFIDENCE IN FLURRIES THIS AFTERNOON...WITH NO IMPACTS TO VIS. HIGH CONFIDENCE IN NO ACCUMULATION. BMD //OUTLOOK FOR ORD/MDW FOR 00Z THURSDAY-12Z TUESDAY...UPDATED 12Z... * WEDNESDAY NIGHT...VFR. * THURSDAY...VFR. SLIGHT CHANCE OF LIGHT RAIN...POSSIBLY MIXING WITH LIGHT SNOW. * FRIDAY...MVFR POSSIBLE. SLIGHT CHANCE OF LIGHT RAIN OR LIGHT SNOW. * SATURDAY...VFR. * SUNDAY...SLIGHT CHANCE OF LIGHT RAIN OR LIGHT SNOW. * MONDAY...SLIGHT CHANCE OF LIGHT SNOW. PAW && .MARINE... 235 AM CST AN AREA OF LOW PRESSURE CONTINUES TO SLOWLY MOVE EAST ACROSS SOUTHERN ONTARIO THIS MORNING. DRAPED SOUTH FROM THIS LOW AND SPANNING MUCH OF THE UPPER AND MIDDLE MISSISSIPPI VALLEY IS A COLD FRONT THAT WILL SLIDE ACROSS THE LAKE LATER THIS MORNING. AHEAD OF IT...THE 15 TO 25 KT WINDS WILL VEER TO THE WEST AND THEN TO THE NORTHWEST THROUGH THE EARLY AFTERNOON HOURS. THE STRONGEST SURGE OF COLD AIR IS NOT ANTICIPATED TO BE UNTIL THE LATER AFTERNOON HOURS FOR THE NORTHERN HALF OF THE LAKE...AND SHORTLY THEREAFTER FOR THE SOUTHERN HALF. IT IS WITH THIS SURGE THAT THE STRONGEST OF WINDS IS ANTICIPATED. HIGH END GALES ARE AGAIN LIKELY...BUT FOR THE ENTIRE SPAN OF THE LAKE WITH THIS EVENT AS OPPOSED TO THE STRONGEST WINDS REMAINING NORTH YESTERDAY. FORECAST SOUNDINGS ARE ALSO INDICATING THE POTENTIAL FOR LOW END STORM FORCE GUSTS. FEEL THAT THE MAJORITY OF THE WINDS WILL REMAIN BELOW STORM CRITERIA FOR THE OPEN WATERS AND WILL ONLY MENTION IN AN OCCASIONAL GROUP. THOUGHTS THEN TURN TO NEARSHORE BURNS HARBOR TO MICHIGAN CITY IN AND 744...AND POTENTIALLY 743 AND GALES. WITH THE STRONG NORTHWESTERLY WINDS EXPECTED...INCREASES THE CHANCES INTO THE EVENING HOURS AND OVERNIGHT. WILL ERR ON THE SIDE OF CAUTION FOR THE FRICTIONLESS MARINE LOCATIONS AND CANCEL THE SMALL CRAFT FOR THOSE LOCATIONS AND HOIST A GALE WARNING. CONDITIONS SET TO IMPROVE LATE TONIGHT AS RIDGING ACROSS THE SURFACE BUILDS...THOUGH PROLONGED STRONG SOUTHWESTERLY FLOW WILL SLOWLY RAMP UP THROUGH WEDNESDAY NIGHT...WITH FLOW PROGGED TO REMAIN BELOW GALE. SHEA && .LOT WATCHES/WARNINGS/ADVISORIES... IL...NONE. IN...NONE. LM...SMALL CRAFT ADVISORY...NEARSHORE GARY TO MICHIGAN CITY IN UNTIL NOON TUESDAY. GALE WARNING...LMZ080-LMZ261-LMZ362-LMZ364-LMZ366-LMZ563-LMZ565- LMZ567-LMZ669-LMZ671-LMZ673-LMZ675-LMZ744-LMZ745-LMZ777- LMZ779-LMZ868-LMZ870-LMZ872-LMZ874-LMZ876-LMZ878 UNTIL 3 AM WEDNESDAY. SMALL CRAFT ADVISORY...NEARSHORE WINTHROP HARBOR TO GARY IN UNTIL 6 PM WEDNESDAY. && $$
AREA FORECAST DISCUSSION
NWS LINCOLN IL
1123 AM CST TUE DEC 27 2011 .DISCUSSION... ISSUED 1010 AM CST TUE DEC 27 2011 BULK OF THE MORNING PRECIPITATION HAS MOVED OUT OF THE AREA...WITH JUST SOME LIGHT SNOW LINGERING NEAR THE INDIANA BORDER. THIS SHOULD MOVE OUT OVER THE NEXT HOUR. BRIEF CLEAR SLOT IS QUICKLY FILLING IN AS A LARGE AREA OF STRATOCUMULUS DROPS SOUTHEAST ACROSS THE WESTERN CWA. HRRR SHOWING SOME SHOWERS DEVELOPING THIS AFTERNOON AS SECONDARY SHORTWAVE SWINGS ACROSS THE CWA...AND SOME CONVECTIVE TYPE ECHOES ARE CURRENTLY SHOWING UP ON BOTH LINCOLN AND DAVENPORT RADARS AS WELL AS VISIBLE SATELLITE IMAGERY. FORECAST SOUNDINGS NOT REALLY SHOWING ANY ICE CRYSTALS LEFT...SO WILL ONLY INCLUDE A MENTION OF SPRINKLES OR FLURRIES AT THIS TIME. SHOULD SEE TEMPERATURES BEGIN TO STEADY OUT OR FALL BY EARLY AFTERNOON... ESPECIALLY ACROSS THE WEST...AS COLDER AIR BEGINS TO FILTER IN BEHIND THE SHORTWAVE. UPDATED ZONES/GRIDS HAVE BEEN SENT. GEELHART && .AVIATION... ISSUED 1123 AM CST TUE DEC 27 2011 EARLIER CLEAR SLOT HAS BEEN FILLING BACK IN...WITH MVFR CLOUD CONDITIONS AT TIMES FROM KBMI-KDEC WESTWARD SLOWLY LIFTING INTO THE VFR RANGE. WILL INCLUDE SOME TEMPO PERIODS FOR THE FIRST COUPLE HOURS OF THE FORECAST FOR CEILINGS IN THE 2000-2500 FOOT RANGE. STILL HAVE SOME IFR CEILINGS LINGERING AT KCMI...BUT THESE SHOULD BE IMPROVING INTO VFR OR HIGH-END MVFR LEVELS VERY SOON. AN UPPER LEVEL WAVE WILL BE SWEEPING ACROSS CENTRAL ILLINOIS THIS AFTERNOON. THIS WILL SCATTER OUT THE CLOUDS EARLY THIS EVENING...AND GUSTY NORTHWEST WINDS WILL BEGIN TO DIMINISH. ANOTHER WEAK BOUNDARY WILL BE APPROACHING FROM THE NORTHWEST LATE IN THE NIGHT WITH SOME MID-LEVEL CLOUDINESS ABOVE 10KFT. NORTHWEST WINDS WILL GRADUALLY TURN TO THE SOUTHWEST AS A SURFACE RIDGE OF HIGH PRESSURE PUSHES ACROSS THE STATE EARLY WEDNESDAY MORNING. GEELHART && .PREV DISCUSSION... ISSUED 255 AM CST TUE DEC 27 2011 SHORT TERM...TODAY THROUGH THURSDAY LOW PRESSURE WILL TRACK FROM WESTERN TENNESSEE EARLY THIS MORNING INTO SOUTHERN OHIO BY MIDDAY...RESULTING IN A CONTINUATION OF LIGHT PRECIP ACROSS THE EASTERN HALF OF THE KILX CWA THROUGH THE MORNING. RADAR TRENDS SUGGEST BACK EDGE OF PRECIP WILL BE ALONG THE I-55 CORRIDOR BY 6 AM...THEN ALONG THE ILLINOIS/INDIANA BORDER BY NOON. A VARIETY OF PRECIP FELL ACROSS CENTRAL ILLINOIS LAST EVENING...WITH MANY REPORTS OF A RAIN/SNOW/SLEET MIXTURE. NAM FORECAST SOUNDINGS INDICATE FURTHER COOLING OF THE COLUMN OVER THE NEXT FEW HOURS... WHICH SHOULD RESULT IN PRECIP CHANGING TO MAINLY SNOW THIS MORNING. 08Z HOURLY OBS ARE BEGINNING TO SHOW THIS TREND...WITH SNOW NOW BEING REPORTED AT A NUMBER OF SITES ACROSS EAST-CENTRAL ILLINOIS. AS A RESULT...HAVE CARRIED CATEGORICAL POPS FOR SNOW ALONG/EAST OF I-57 THIS MORNING...WITH ACCUMULATIONS OF AN INCH OR LESS. HAVE TAPERED POPS TO JUST LOW CHANCE ALONG I-55...AND NOTHING FURTHER WEST. AS THE LOW PULLS AWAY AND AN APPROACHING COLD FRONT SWINGS THROUGH...GUSTY NORTHWESTERLY WINDS WILL DEVELOP DURING THE LATE MORNING INTO THE AFTERNOON. FORECAST SOUNDINGS SUGGEST SUSTAINED WINDS OF 10 TO 20 MPH...WITH GUSTS AS HIGH AS 30 MPH AT TIMES. DUE TO THE BRISK WINDS AND AMPLE CLOUD COVER...TEMPS WILL NOT WARM MUCH TODAY...WITH HIGHS ONLY CLIMBING INTO THE UPPER 30S TO AROUND 40 DEGREES. CHILLY WEATHER WILL BE IN STORE TONIGHT INTO WEDNESDAY...COURTESY OF HIGH PRESSURE SLIDING THROUGH THE REGION. OVERNIGHT LOWS WILL DIP INTO THE LOWER TO MIDDLE 20S...WHILE HIGHS ON WEDNESDAY REMAIN IN THE UPPER 30S AND LOWER 40S. W/NW UPPER FLOW WILL PREVAIL ACROSS THE CENTRAL/EASTERN CONUS THROUGH THURSDAY...WITH A NUMBER OF WEAK IMPULSES DROPPING THROUGH THE PREVAILING FLOW PATTERN. THE FIRST WAVE WILL TRACK ACROSS THE UPPER MIDWEST/GREAT LAKES WEDNESDAY NIGHT...WITH ANY ASSOCIATED PRECIP REMAINING WELL NORTH OF CENTRAL ILLINOIS. A SECOND STRONGER WAVE IS EXPECTED TO DIG A BIT FURTHER SOUTH THURSDAY NIGHT...POSSIBLY BRINGING LIGHT PRECIP AS FAR SOUTH AS THE I-74 CORRIDOR. THANKS TO A SOUTHERLY FLOW AHEAD OF THE SYSTEM...TEMPS WILL BE WARM ENOUGH TO SUPPORT A RAIN/SNOW MIX. THINK STRONGEST DYNAMICS WILL REMAIN ACROSS NORTHERN ILLINOIS...HOWEVER HAVE INCLUDED SLIGHT CHANCE POPS ALONG/NORTH OF I-74. LONG TERM...FRIDAY THROUGH MONDAY STILL QUITE A BIT OF MODEL DISCREPANCY IN THE EXTENDED...SO FORECAST CONFIDENCE REMAINS LOW BEYOND SATURDAY. ECMWF CONTINUES TO FEATURE AN AGGRESSIVELY DIGGING UPPER TROUGH ACROSS THE EASTERN CONUS EARLY NEXT WEEK...WHILE THE GFS IS MUCH LESS AMPLIFIED. GIVEN POOR AGREEMENT AND RUN-TO-RUN CONSISTENCY...HAVE OPTED TO LEAVE FORECAST DRY...ALTHOUGH IF ECMWF PANS OUT...PRECIP WOULD BE POSSIBLE ACROSS AT LEAST THE E/SE CWA SUNDAY INTO MONDAY. REGARDLESS OF WHICH MODEL TURNS OUT TO BE RIGHT...IT APPEARS A CHUNK OF COLDER AIR IS ON THE WAY FOR EARLY NEXT WEEK. IF THE ECMWF VERIFIES...TEMPS COULD BE WELL BELOW NORMAL. AT THIS TIME...WILL REMAIN CONSERVATIVE AND ONLY DROP TEMPS BACK DOWN TO NEAR NORMAL BY MONDAY. BARNES && .ILX WATCHES/WARNINGS/ADVISORIES... NONE. && $$
AREA FORECAST DISCUSSION
NWS LINCOLN IL
1012 AM CST TUE DEC 27 2011 .DISCUSSION... ISSUED 1010 AM CST TUE DEC 27 2011 BULK OF THE MORNING PRECIPITATION HAS MOVED OUT OF THE AREA...WITH JUST SOME LIGHT SNOW LINGERING NEAR THE INDIANA BORDER. THIS SHOULD MOVE OUT OVER THE NEXT HOUR. BRIEF CLEAR SLOT IS QUICKLY FILLING IN AS A LARGE AREA OF STRATOCUMULUS DROPS SOUTHEAST ACROSS THE WESTERN CWA. HRRR SHOWING SOME SHOWERS DEVELOPING THIS AFTERNOON AS SECONDARY SHORTWAVE SWINGS ACROSS THE CWA...AND SOME CONVECTIVE TYPE ECHOES ARE CURRENTLY SHOWING UP ON BOTH LINCOLN AND DAVENPORT RADARS AS WELL AS VISIBLE SATELLITE IMAGERY. FORECAST SOUNDINGS NOT REALLY SHOWING ANY ICE CRYSTALS LEFT...SO WILL ONLY INCLUDE A MENTION OF SPRINKLES OR FLURRIES AT THIS TIME. SHOULD SEE TEMPERATURES BEGIN TO STEADY OUT OR FALL BY EARLY AFTERNOON... ESPECIALLY ACROSS THE WEST...AS COLDER AIR BEGINS TO FILTER IN BEHIND THE SHORTWAVE. UPDATED ZONES/GRIDS HAVE BEEN SENT. GEELHART && .AVIATION... ISSUED 518 AM CST TUE DEC 27 2011 UPPER LOW OVER NORTHERN MS WITH LARGE AREA OF MIXED PRECIPITATION EXTENDING NORTH THROUGH IL...MAINLY ALONG AND EAST OF INTERSTATE 55. BACK EDGE OF THE RAIN/SNOW IS MAKING STEADY PROGRESS AND WILL BE EAST OF SPI/BMI BY 13Z...DEC BY 14Z...AND CMI AROUND 16Z. A PERIOD OF CIGS BELOW 500 FT AND 3-5SM FOG WILL FOLLOW THE PRECIPITATION FOR A COUPLE OF HOURS...WITH TEMPORARY VFR CONDITIONS THEREAFTER. A COLD FRONT MOVING INTO EASTERN IA WILL MOVE THROUGH CENTRAL IL BEFORE 18Z. SATELLITE IMAGERY SHOWS ANOTHER BATCH OF MVFR STRATOCU MOVING SOUTHEAST INTO NORTHERN IA BEHIND THE FRONT...AND THE SHORT RANGE MODELS INDICATE THAT THESE CLOUDS WILL CONTINUE INTO CENTRAL IL. WINDS AFTER FRONTAL PASSAGE WILL INCREASE FROM THE NORTHWEST AT 20-25 KT WITH HIGHER GUSTS. UPSTREAM PROFILERS ARE SHOWING 925 MB WINDS OF 30-35 KT AT THIS TIME. CLOUDS WILL MOVE OUT AND WINDS WILL DIMINISH BETWEEN 00Z AND 03Z WED. AT THIS TIME...SIGNIFICANT FOG APPEARS UNLIKELY TONIGHT DUE TO THE DRIER SURFACE DEWPOINTS AND SUFFICIENT BREEZE TO KEEP THE AIR MIXED. 04 && .PREV DISCUSSION... ISSUED 255 AM CST TUE DEC 27 2011 SHORT TERM...TODAY THROUGH THURSDAY LOW PRESSURE WILL TRACK FROM WESTERN TENNESSEE EARLY THIS MORNING INTO SOUTHERN OHIO BY MIDDAY...RESULTING IN A CONTINUATION OF LIGHT PRECIP ACROSS THE EASTERN HALF OF THE KILX CWA THROUGH THE MORNING. RADAR TRENDS SUGGEST BACK EDGE OF PRECIP WILL BE ALONG THE I-55 CORRIDOR BY 6 AM...THEN ALONG THE ILLINOIS/INDIANA BORDER BY NOON. A VARIETY OF PRECIP FELL ACROSS CENTRAL ILLINOIS LAST EVENING...WITH MANY REPORTS OF A RAIN/SNOW/SLEET MIXTURE. NAM FORECAST SOUNDINGS INDICATE FURTHER COOLING OF THE COLUMN OVER THE NEXT FEW HOURS... WHICH SHOULD RESULT IN PRECIP CHANGING TO MAINLY SNOW THIS MORNING. 08Z HOURLY OBS ARE BEGINNING TO SHOW THIS TREND...WITH SNOW NOW BEING REPORTED AT A NUMBER OF SITES ACROSS EAST-CENTRAL ILLINOIS. AS A RESULT...HAVE CARRIED CATEGORICAL POPS FOR SNOW ALONG/EAST OF I-57 THIS MORNING...WITH ACCUMULATIONS OF AN INCH OR LESS. HAVE TAPERED POPS TO JUST LOW CHANCE ALONG I-55...AND NOTHING FURTHER WEST. AS THE LOW PULLS AWAY AND AN APPROACHING COLD FRONT SWINGS THROUGH...GUSTY NORTHWESTERLY WINDS WILL DEVELOP DURING THE LATE MORNING INTO THE AFTERNOON. FORECAST SOUNDINGS SUGGEST SUSTAINED WINDS OF 10 TO 20 MPH...WITH GUSTS AS HIGH AS 30 MPH AT TIMES. DUE TO THE BRISK WINDS AND AMPLE CLOUD COVER...TEMPS WILL NOT WARM MUCH TODAY...WITH HIGHS ONLY CLIMBING INTO THE UPPER 30S TO AROUND 40 DEGREES. CHILLY WEATHER WILL BE IN STORE TONIGHT INTO WEDNESDAY...COURTESY OF HIGH PRESSURE SLIDING THROUGH THE REGION. OVERNIGHT LOWS WILL DIP INTO THE LOWER TO MIDDLE 20S...WHILE HIGHS ON WEDNESDAY REMAIN IN THE UPPER 30S AND LOWER 40S. W/NW UPPER FLOW WILL PREVAIL ACROSS THE CENTRAL/EASTERN CONUS THROUGH THURSDAY...WITH A NUMBER OF WEAK IMPULSES DROPPING THROUGH THE PREVAILING FLOW PATTERN. THE FIRST WAVE WILL TRACK ACROSS THE UPPER MIDWEST/GREAT LAKES WEDNESDAY NIGHT...WITH ANY ASSOCIATED PRECIP REMAINING WELL NORTH OF CENTRAL ILLINOIS. A SECOND STRONGER WAVE IS EXPECTED TO DIG A BIT FURTHER SOUTH THURSDAY NIGHT...POSSIBLY BRINGING LIGHT PRECIP AS FAR SOUTH AS THE I-74 CORRIDOR. THANKS TO A SOUTHERLY FLOW AHEAD OF THE SYSTEM...TEMPS WILL BE WARM ENOUGH TO SUPPORT A RAIN/SNOW MIX. THINK STRONGEST DYNAMICS WILL REMAIN ACROSS NORTHERN ILLINOIS...HOWEVER HAVE INCLUDED SLIGHT CHANCE POPS ALONG/NORTH OF I-74. LONG TERM...FRIDAY THROUGH MONDAY STILL QUITE A BIT OF MODEL DISCREPANCY IN THE EXTENDED...SO FORECAST CONFIDENCE REMAINS LOW BEYOND SATURDAY. ECMWF CONTINUES TO FEATURE AN AGGRESSIVELY DIGGING UPPER TROUGH ACROSS THE EASTERN CONUS EARLY NEXT WEEK...WHILE THE GFS IS MUCH LESS AMPLIFIED. GIVEN POOR AGREEMENT AND RUN-TO-RUN CONSISTENCY...HAVE OPTED TO LEAVE FORECAST DRY...ALTHOUGH IF ECMWF PANS OUT...PRECIP WOULD BE POSSIBLE ACROSS AT LEAST THE E/SE CWA SUNDAY INTO MONDAY. REGARDLESS OF WHICH MODEL TURNS OUT TO BE RIGHT...IT APPEARS A CHUNK OF COLDER AIR IS ON THE WAY FOR EARLY NEXT WEEK. IF THE ECMWF VERIFIES...TEMPS COULD BE WELL BELOW NORMAL. AT THIS TIME...WILL REMAIN CONSERVATIVE AND ONLY DROP TEMPS BACK DOWN TO NEAR NORMAL BY MONDAY. BARNES && .ILX WATCHES/WARNINGS/ADVISORIES... NONE. && $$
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
1004 AM CST TUE DEC 27 2011 .DISCUSSION... 330 AM CST THE FORECAST CHALLENGES ARE FIRST ON THE IMMEDIATE SHORT TERM WITH PRECIPITATION GRADUALLY SHIFTING EASTWARD THIS MORNING...THEN THE LAKE EFFECT SHOWER POTENTIAL INTO NORTHWEST INDIANA THIS AFTERNOON AND EVENING. THE ACTIVE FLOW PATTERN ACROSS THE NORTHERN U.S. AND SOME UNDULATIONS IN THIS INTO THE NEW YEAR KEEP THE FORECAST INTERESTING LOOKING FORWARD. SHORT TERM...LOW PRESSURE IS DEVELOPING FAIRLY RAPIDLY UNDER STRONG JET SUPPORT ACROSS WESTERN KY. MOIST ADVECTION ALOFT AND ASSOCIATED ASCENT CONTINUES TO WORK ITS WAY ACROSS NORTHWEST INDIANA. AN ELONGATED NORTHERN STREAM WAVE PUSHING EAST ACROSS THE REGION HAS INTERACTED WITH THIS...HELPING TO PRODUCE BANDS OF MODERATE PRECIP AT TIMES WHERE CONVERGENCE OF ECHOES WAS OBSERVED /AND LIKELY IMPLYING FRONTOGENETIC FORCING/. WITHIN THESE...A FEW REPORTS OF SLEET WERE OBSERVED/REPORTED OR ESTIMATED THROUGH UNKNOWN PRECIP AUTOMATED REPORTS. STRONGER FORCING LIFTING NORTH ACROSS EASTERN IL/WESTERN IN HAS HELPED TO LEAD TO EVAPORATIONAL COOLING SUPPORTING SNOW...AND BENTON COUNTY REPORTED A COATING OF SNOW ON THEIR PAVEMENT AS OF 300 AM. EXPECT THE AREAS RECEIVING PRECIPITATION AT DAYBREAK TO BE MAINLY A WET SNOW...WITH A LITTLE LIGHT RAIN POSSIBLY JUST BEFORE IT ENDS ON THE WESTERN PERIPHERY. THE SHIELD OF PRECIP WILL TAKE A WHILE TO EVOLVE EAST OUT OF THE AREA BASED ON THE QG FORCING ON THE RUC AS WELL AS WATER VAPOR TRENDS WITH THE DRY SLOT NOSE LIFTING INTO CENTRAL IN HELPING TO KEEP MAINLY SNOW GOING IN THE SOUTHEAST FORECAST AREA THIS MORNING. MAXIMUM ACCUMULATIONS NEAR AN INCH TOWARDS FOWLER AND RENSSALEAR STILL LOOK VALID. IN THE FAR SOUTH AND SOUTHEAST CHICAGO METRO WHILE SNOW MAY STILL BE OCCURRING THROUGH 9 AM OR SO...NO ACCUMULATION IS EXPECTED. THIS AFTERNOON...STRONG NORTH TO NORTHWEST WINDS IN THE WAKE OF THE SYSTEM ESTABLISH THEMSELVES DOWN THE FETCH OF LAKE MI THIS AFTERNOON. CONVERGENCE STREAMLINES FROM THE 27.06 NAM FAVOR A CORRIDOR OF SATURATED CONVERGENCE CENTERED ON MICHIGAN CITY...WITH SOME FURTHER WEST TOWARDS PORTER COUNTY. LAKE INDUCED EQUILIBRIUM LEVELS ARE PROJECTED OVER 5000 FT ON THE NAM FOR LATE THIS AFTERNOON AND EVENING AND THUS HAVE INCREASED POPS IN THAT AREA FOR SOME SNOW SHOWERS. FROM THIS...ONLY AN ADDITIONAL DUSTING IS EXPECTED WITH POTENTIAL FOR MORE JUST EAST OF THE FORECAST AREA. TONIGHT THROUGH THURSDAY...THE TEMPERATURES TONIGHT WILL BE A BATTLE BETWEEN THE COLD AND DRY AIR ADVECTION THIS EVENING AND THEN MID TO HIGH CLOUDS ON THE INCREASE FROM THE WEST OVERNIGHT WITH AN APPROACHING SHORT WAVE. IN ADDITION...LINGERING STRATOCU IN THE CAA REGIME IS LIKELY EARLY THIS EVENING...AND THAT MAY RESIDE THROUGH A GOOD PART OF THE NIGHT IN EASTERN AREAS. MODEL SPREAD REFLECTS THIS...VARYING UP TO TEN DEGREES IN SOME LOCATIONS. CONFIDENCE IS THUS MINIMAL ON TONIGHTS LOWS...AND AM NEAR THE CENTER OF THE SPREAD AT THIS TIME. A STRONGER SHORT WAVE ARRIVES INTO SOUTHERN WI ON LATE WEDNESDAY NIGHT INTO THURSDAY MORNING. THIS IS A TRUE QUICK MOVING CLIPPER...WITH ITS BEST MOISTURE SUPPORT ALONG AND NORTH OF ITS PATH WHERE THE TIGHT MID- LEVEL THERMAL GRADIENT EXISTS. WHILE THERE IS FAIRLY STOUT 850-600 MB WAA AHEAD OF THIS FEATURE WED AFTERNOON AND EVENING...THE COLUMN LOOKS MUCH TOO DRY FOR PRECIP. SO ONLY HAVE POPS NEAR THE WI STATE LINE WITH THE ACTUAL LOW CENTER PASSAGE. THURSDAY NIGHT...WHAT HAD BEEN A DEEP SLOW-MOVING LOW IN THE LONGER RANGE FORECAST DAYS AGO HAS TRENDED TOWARDS A SHARP SOUTHEAST DIVING CLIPPER THAT STILL IS FAIRLY DEEP IN PRESSURE FOR CLIPPERS /~1002 MB/. THE PATH ON THE GFS AND EC FAVOR OUR AREA TO SEE SOME PRECIP...BUT EVEN A SLIGHT SHIFT NORTH OR SOUTH WOULD GREATLY REDUCE THEM AS IT IS A FAIRLY NARROW AXIS OF PRECIP WITH SUCH A STRUCTURE. INDEED THE 27.06 NAM IS A SOLUTION THAT IS FURTHER NORTH WITH LITTLE QPF. THE EC FOR TWO CONSECUTIVE RUNS HAS BEEN SLOWER THAN THE GFS...FAVORING OVERNIGHT THU AS OPPOSED TO THE EVE FOR INFLUENCE OVER OUR AREA. BOTH MODELS WOULD STILL SUPPORT SNOW CHANCES...BUT THE EC IS BETTER LOOKING FOR THAT WITH SLIGHTLY DEEPER HEIGHT FALLS AND GREATER MIXING RATIOS ON THE LIFTING SURFACES / 2.5-3 G/KG /. UNFORTUNATELY...THIS WAVE IS ONE OF MANY IN THE NORTHERN PACIFIC RIGHT NOW AND THUS NOT WELL SAMPLED. SO HAVE KEPT POPS ONLY AT A CHANCE BUT HAVE INCREASE VALUES. BEYOND...THE PROGRESSIVE PATTERN CONTINUES WITH AN IMMEDIATE INCREASE IN HEIGHTS AND A LOW-LEVEL THERMAL RIDGE INTO THE AREA. THE GFS...EC...AND GEM ALL BRING 850 MB TEMPERATURES TO ABOVE 8C ON SATURDAY. BIAS-CORRECTED FORECASTS FROM THESE MODELS BLENDED TOGETHER YIELDS HIGHS FROM THE UPPER 40S TO A STAGGERING MID 50S. WITH SUCH A QUICK TURNAROUND FROM COOL AIR ADVECTION BEHIND THE WAVE THURSDAY NIGHT/EARLY FRIDAY...WILL NOT BE GOING THAT HIGH. BUT HAVE BLENDED THE GOING FORECAST ALMOST 50 PERCENT WITH THESE. THIS AMPLIFIED PATTERN WHICH BRINGS IN THE WARMER REGIME IS AHEAD OF A DIGGING JET TO START THE NEW YEAR WHICH HAS BEEN HINTED AT IN SOLUTIONS FOR A WHILE. THIS WOULD AT LEAST BRING TEMPERATURES DOWN FOR EARLY NEXT WEEK...BUT CONFIDENCE IS LOW IN THIS AS WELL AS THE PRECIP CHANCES WITH THE SYSTEM EVOLVING ON THE JET UNDULATION. LOOKING INTO NEXT WEEK...DESPITE THE CHANCES FOR COOLER TEMPERATURES INITIALLY...THE 8 TO 14 DAY CPC OUTLOOK AND ESPECIALLY THE NAEFS MEMBERS FAVOR ABOVE NORMAL TEMPERATURES IN GENERAL. MTF && .AVIATION... //ORD AND MDW CONCERNS...UPDATED 16Z... * CIG TRENDS...POTENTIAL FOR MVFR CONDITIONS TO RETURN. * STRONG GUSTY NNW WINDS. * POSSIBILITY OF FLURRIES THIS AFTERNOON. BMD //DISCUSSION...UPDATED 12Z... AREAS OF RAIN AND MIXED RAIN/SNOW OVER THE CHICAGO METRO TERMINALS HAVE DECREASED IN SIZE AND MOVED TO THE EAST THROUGH THE EARLY MORNING HOURS AS THE LOW PRESSURE SYSTEM CENTERED OVER WESTERN KY MOVES TO THE NORTHEAST. AS THE PRECIPITATION ENDS CIGS MAY IMPROVE JUST A LITTLE BIT. BUT MORE SIGNIFICANT IMPROVEMENT WILL BE BEHIND A COLD FRONT THAT WILL MOVE ACROSS NORTHERN IL AND NORTHWEST IN THIS MORNING. THIS FRONT WILL TURN WINDS TO THE NORTHWEST AND INCREASE THE SPEEDS BY LATE MORNING. FLURRIES ARE POSSIBLE BEHIND THE FRONT IN THE COLDER AIR AT ALL THE TERMINALS THIS AFTERNOON. PAW //ORD AND MDW CONFIDENCE...UPDATED 16Z... * MEDIUM CONFIDENCE ON VFR CONDITIONS PREVAILING REMAINDER OF DAY. LOW CONFIDENCE ON MVFR CONDITIONS RETURNING. * HIGH CONFIDENCE ON WIND DIRECTION...MEDIUM CONFIDENCE ON WIND SPEEDS/GUSTS AND TIMING ARRIVAL OF GUSTS. * LOW CONFIDENCE ON FLURRIES THIS AFTERNOON. BMD //OUTLOOK FOR ORD/MDW FOR 00Z THURSDAY-12Z TUESDAY...UPDATED 12Z... * WEDNESDAY NIGHT...VFR. * THURSDAY...VFR. SLIGHT CHANCE OF LIGHT RAIN...POSSIBLY MIXING WITH LIGHT SNOW. * FRIDAY...MVFR POSSIBLE. SLIGHT CHANCE OF LIGHT RAIN OR LIGHT SNOW. * SATURDAY...VFR. * SUNDAY...SLIGHT CHANCE OF LIGHT RAIN OR LIGHT SNOW. * MONDAY...SLIGHT CHANCE OF LIGHT SNOW. PAW && .MARINE... 235 AM CST AN AREA OF LOW PRESSURE CONTINUES TO SLOWLY MOVE EAST ACROSS SOUTHERN ONTARIO THIS MORNING. DRAPED SOUTH FROM THIS LOW AND SPANNING MUCH OF THE UPPER AND MIDDLE MISSISSIPPI VALLEY IS A COLD FRONT THAT WILL SLIDE ACROSS THE LAKE LATER THIS MORNING. AHEAD OF IT...THE 15 TO 25 KT WINDS WILL VEER TO THE WEST AND THEN TO THE NORTHWEST THROUGH THE EARLY AFTERNOON HOURS. THE STRONGEST SURGE OF COLD AIR IS NOT ANTICIPATED TO BE UNTIL THE LATER AFTERNOON HOURS FOR THE NORTHERN HALF OF THE LAKE...AND SHORTLY THEREAFTER FOR THE SOUTHERN HALF. IT IS WITH THIS SURGE THAT THE STRONGEST OF WINDS IS ANTICIPATED. HIGH END GALES ARE AGAIN LIKELY...BUT FOR THE ENTIRE SPAN OF THE LAKE WITH THIS EVENT AS OPPOSED TO THE STRONGEST WINDS REMAINING NORTH YESTERDAY. FORECAST SOUNDINGS ARE ALSO INDICATING THE POTENTIAL FOR LOW END STORM FORCE GUSTS. FEEL THAT THE MAJORITY OF THE WINDS WILL REMAIN BELOW STORM CRITERIA FOR THE OPEN WATERS AND WILL ONLY MENTION IN AN OCCASIONAL GROUP. THOUGHTS THEN TURN TO NEARSHORE BURNS HARBOR TO MICHIGAN CITY IN AND 744...AND POTENTIALLY 743 AND GALES. WITH THE STRONG NORTHWESTERLY WINDS EXPECTED...INCREASES THE CHANCES INTO THE EVENING HOURS AND OVERNIGHT. WILL ERR ON THE SIDE OF CAUTION FOR THE FRICTIONLESS MARINE LOCATIONS AND CANCEL THE SMALL CRAFT FOR THOSE LOCATIONS AND HOIST A GALE WARNING. CONDITIONS SET TO IMPROVE LATE TONIGHT AS RIDGING ACROSS THE SURFACE BUILDS...THOUGH PROLONGED STRONG SOUTHWESTERLY FLOW WILL SLOWLY RAMP UP THROUGH WEDNESDAY NIGHT...WITH FLOW PROGGED TO REMAIN BELOW GALE. SHEA && .LOT WATCHES/WARNINGS/ADVISORIES... IL...NONE. IN...NONE. LM...SMALL CRAFT ADVISORY...NEARSHORE GARY TO MICHIGAN CITY IN UNTIL NOON TUESDAY. GALE WARNING...LMZ080-LMZ261-LMZ362-LMZ364-LMZ366-LMZ563-LMZ565- LMZ567-LMZ669-LMZ671-LMZ673-LMZ675-LMZ744-LMZ745-LMZ777- LMZ779-LMZ868-LMZ870-LMZ872-LMZ874-LMZ876-LMZ878 UNTIL 3 AM WEDNESDAY. SMALL CRAFT ADVISORY...NEARSHORE WINTHROP HARBOR TO GARY IN UNTIL 6 PM WEDNESDAY. && $$
AREA FORECAST DISCUSSION
NWS GOODLAND KS
1036 AM MST TUE DEC 27 2011 .UPDATE... 1034 AM MST TUE DEC 27 2011 UPDATED TODAY/S HIGH TEMPS BY RAISING MOST AREAS UPWARD BY A CATEGORY BASED ON LATEST TRENDS IN THE SFC OBS. NO OTHER CHANGES WERE NEEDED. 05 && .SYNOPSIS... CURRENT SATELLITE IMAGERY AND RUC UPPER AIR ANALYSIS SHOW A HIGH PRESSURE OVER THE SOUTHWEST CONUS...WITH A SHORT WAVE TROUGH AND MID LEVEL MOISTURE MOVING AROUND THE NORTHERN PERIPHERY OF THE HIGH ALONG THE US/CANADIAN BORDER. OVER THE CENTRAL PLAINS A SHORT WAVE TROUGH IN THE NORTHWEST FLOW WAS PRODUCING A FEW CLOUDS. CLOSER TO HOME A SURFACE HIGH PRESSURE WAS BUILDING INTO THE TRI-STATE AREA. LATEST REPORTS OF SNOW DEPTH SHOW 2 TO 10 INCHES STILL ON THE GROUND FOR AREAS OF CENTRAL AND SOUTHWEST KANSAS...SO AM EXPECTING THIS TO HAVE A COOLING EFFECT ON TEMPERATURES THROUGH THE PERIOD. JTL && .SHORT TERM (TODAY-THURSDAY)... 228 AM MST TUE DEC 27 2011 TEMPERATURES WILL BE THE MAIN CONCERN FOR THIS PERIOD. SURFACE HIGH PRESSURE WILL MOVE ACROSS THE TRI-STATE AREA TODAY...PRECEDING A SURFACE AND UPPER LEVEL TROUGH THAT WILL MOVE THROUGH DURING THE EVENING HOURS. MODELS HAVE REDUCED THE AMOUNT OF MOISTURE AND LIFT WITH THE TROUGH PASSAGE...SO WILL FOLLOW PREVIOUS SHIFT AND KEEP OUT ANY MENTION OF PRECIPITATION. HIGH TEMPERATURES A BIT TRICKY DUE TO THE COMBINED EFFECTS OF CLOUD COVER AND SOUTHERLY WINDS BRINGING IN COOLER AIR FROM THE SNOW FIELD...BUT OVERALL TEMPERATURES TODAY WILL BE COOLER THAN YESTERDAY. LOWS TONIGHT WILL BE A FEW DEGREES WARMER THAN LAST NIGHT. WEDNESDAY MINOR RIPPLES WILL MOVE THROUGH THE UPPER LEVEL FLOW OVER THE AREA...PRODUCING A FEW CLOUDS AT BEST. WITH WESTERLY WINDS BRINGING IN WARMER AIR...TEMPERATURES WILL BE WARMER THAN TUESDAY. THURSDAY A MINOR SHORT WAVE TROUGH AND SOME MOISTURE MOVE THROUGH THE UPPER LEVEL FLOW OVER THE AREA. THIS TROUGH WILL HAVE MORE LIFT WITH IT...BUT WILL HAVE THE BEST LIFT BELOW THE MOISTURE. AS SUCH WILL LEAVE OUT A MENTION OF ANY PRECIPITATION AS THE TROUGH MOVES THROUGH. AT THE SURFACE WINDS WILL BECOME NORTHWEST BEHIND THE TROUGH AND STRENGTHEN SOME...WITH THE STRONGER WINDS OVER THE NEBRASKA COUNTIES. TEMPERATURES WILL CONTINUE THE WARMING TREND. 850MB TEMPERATURES WARM TO NEAR 10C DURING THE DAY...SO WENT WITH THE WARMER GUIDANCE SINCE 850MB TEMPERATURES OF 3C YESTERDAY AND NORTHWEST WINDS PRODUCED HIGHS AROUND 50 DEGREES...SO HIGHS AROUND 60 ARE NOT OUT OF THE QUESTION. JTL .LONG TERM (FRIDAY-MONDAY)... 228 AM MST TUE DEC 27 2011 LONG RANGE MODELS CONTINUE TO SHOW WEAK SHORT WAVE TROUGHS MOVING ACROSS THE HIGH PLAINS IN PSEUDO ZONAL FLOW THROUGH THE WEEKEND. THE STRONGEST WAVE IS DUE SATURDAY AFTERNOON OR SATURDAY NIGHT DEPENDING ON MODEL PREFERENCE...BUT MOISTURE APPEARS LIMITED REGARDLESS SO WILL KEEP FORECASTS DRY. WARM AIR ADVECTION AND ABOVE NORMAL 500 MB HEIGHTS SUPPORT DECENT WARM/UP BETWEEN THE SHORT WAVES...ESPECIALLY FRIDAY WHEN 850 MB TEMPERATURES ARE PROGGED TO REACH BETWEEN 12-14 DEGREES CELSIUS. AGREE WITH SURROUNDING OFFICES TO INCREASE MAXIMUM TEMPERATURE FORECASTS THAT DAY. EVEN WITH WARM AIR ADVECTION...TEMPERATURES SOUTH OF INTERSTATE 70 WILL BE DEPENDENT ON THE AMOUNT OF SNOW PACK MELTING THAT OCCURS BETWEEN NOW AND FRIDAY. EXPECT ENOUGH MELTING TO ALLOW TEMPERATURES TO FINALLY REACH INTO THE 50S THERE BY FRIDAY. && .AVIATION... 1018 AM MST TUE DEC 27 2011 FOR THE 18Z TAFS...VFR CONDITIONS WILL PREVAIL THROUGH THE PERIOD. LIGHT WINDS HAVE BACKED TO THE SOUTHWEST AS LOW PRESSURE DEEPENED TO THE NORTHEAST OF THE TERMINALS. WINDS WILL RETURN TO THE NORTHWEST OVERNIGHT AS HIGH PRESSURE BUILDS ACROSS THE REGION. CJS && .GLD WATCHES/WARNINGS/ADVISORIES... KS...NONE. NE...NONE. CO...NONE. && $$
AREA FORECAST DISCUSSION
NWS GOODLAND KS
1018 AM MST TUE DEC 27 2011 .SYNOPSIS... CURRENT SATELLITE IMAGERY AND RUC UPPER AIR ANALYSIS SHOW A HIGH PRESSURE OVER THE SOUTHWEST CONUS...WITH A SHORT WAVE TROUGH AND MID LEVEL MOISTURE MOVING AROUND THE NORTHERN PERIPHERY OF THE HIGH ALONG THE US/CANADIAN BORDER. OVER THE CENTRAL PLAINS A SHORT WAVE TROUGH IN THE NORTHWEST FLOW WAS PRODUCING A FEW CLOUDS. CLOSER TO HOME A SURFACE HIGH PRESSURE WAS BUILDING INTO THE TRI-STATE AREA. LATEST REPORTS OF SNOW DEPTH SHOW 2 TO 10 INCHES STILL ON THE GROUND FOR AREAS OF CENTRAL AND SOUTHWEST KANSAS...SO AM EXPECTING THIS TO HAVE A COOLING EFFECT ON TEMPERATURES THROUGH THE PERIOD. JTL && .SHORT TERM (TODAY-THURSDAY)... 228 AM MST TUE DEC 27 2011 TEMPERATURES WILL BE THE MAIN CONCERN FOR THIS PERIOD. SURFACE HIGH PRESSURE WILL MOVE ACROSS THE TRI-STATE AREA TODAY...PRECEDING A SURFACE AND UPPER LEVEL TROUGH THAT WILL MOVE THROUGH DURING THE EVENING HOURS. MODELS HAVE REDUCED THE AMOUNT OF MOISTURE AND LIFT WITH THE TROUGH PASSAGE...SO WILL FOLLOW PREVIOUS SHIFT AND KEEP OUT ANY MENTION OF PRECIPITATION. HIGH TEMPERATURES A BIT TRICKY DUE TO THE COMBINED EFFECTS OF CLOUD COVER AND SOUTHERLY WINDS BRINGING IN COOLER AIR FROM THE SNOW FIELD...BUT OVERALL TEMPERATURES TODAY WILL BE COOLER THAN YESTERDAY. LOWS TONIGHT WILL BE A FEW DEGREES WARMER THAN LAST NIGHT. WEDNESDAY MINOR RIPPLES WILL MOVE THROUGH THE UPPER LEVEL FLOW OVER THE AREA...PRODUCING A FEW CLOUDS AT BEST. WITH WESTERLY WINDS BRINGING IN WARMER AIR...TEMPERATURES WILL BE WARMER THAN TUESDAY. THURSDAY A MINOR SHORT WAVE TROUGH AND SOME MOISTURE MOVE THROUGH THE UPPER LEVEL FLOW OVER THE AREA. THIS TROUGH WILL HAVE MORE LIFT WITH IT...BUT WILL HAVE THE BEST LIFT BELOW THE MOISTURE. AS SUCH WILL LEAVE OUT A MENTION OF ANY PRECIPITATION AS THE TROUGH MOVES THROUGH. AT THE SURFACE WINDS WILL BECOME NORTHWEST BEHIND THE TROUGH AND STRENGTHEN SOME...WITH THE STRONGER WINDS OVER THE NEBRASKA COUNTIES. TEMPERATURES WILL CONTINUE THE WARMING TREND. 850MB TEMPERATURES WARM TO NEAR 10C DURING THE DAY...SO WENT WITH THE WARMER GUIDANCE SINCE 850MB TEMPERATURES OF 3C YESTERDAY AND NORTHWEST WINDS PRODUCED HIGHS AROUND 50 DEGREES...SO HIGHS AROUND 60 ARE NOT OUT OF THE QUESTION. JTL .LONG TERM (FRIDAY-MONDAY)... 228 AM MST TUE DEC 27 2011 LONG RANGE MODELS CONTINUE TO SHOW WEAK SHORT WAVE TROUGHS MOVING ACROSS THE HIGH PLAINS IN PSEUDO ZONAL FLOW THROUGH THE WEEKEND. THE STRONGEST WAVE IS DUE SATURDAY AFTERNOON OR SATURDAY NIGHT DEPENDING ON MODEL PREFERENCE...BUT MOISTURE APPEARS LIMITED REGARDLESS SO WILL KEEP FORECASTS DRY. WARM AIR ADVECTION AND ABOVE NORMAL 500 MB HEIGHTS SUPPORT DECENT WARM/UP BETWEEN THE SHORT WAVES...ESPECIALLY FRIDAY WHEN 850 MB TEMPERATURES ARE PROGGED TO REACH BETWEEN 12-14 DEGREES CELSIUS. AGREE WITH SURROUNDING OFFICES TO INCREASE MAXIMUM TEMPERATURE FORECASTS THAT DAY. EVEN WITH WARM AIR ADVECTION...TEMPERATURES SOUTH OF INTERSTATE 70 WILL BE DEPENDENT ON THE AMOUNT OF SNOW PACK MELTING THAT OCCURS BETWEEN NOW AND FRIDAY. EXPECT ENOUGH MELTING TO ALLOW TEMPERATURES TO FINALLY REACH INTO THE 50S THERE BY FRIDAY. && .AVIATION... 1018 AM MST TUE DEC 27 2011 FOR THE 18Z TAFS...VFR CONDITIONS WILL PREVAIL THROUGH THE PERIOD. LIGHT WINDS HAVE BACKED TO THE SOUTHWEST AS LOW PRESSURE DEEPENED TO THE NORTHEAST OF THE TERMINALS. WINDS WILL RETURN TO THE NORTHWEST OVERNIGHT AS HIGH PRESSURE BUILDS ACROSS THE REGION. CJS && .GLD WATCHES/WARNINGS/ADVISORIES... KS...NONE. NE...NONE. CO...NONE. && $$
THE PREVIOUS SHORT TERM FORECAST DISCUSSION FOLLOWS...

/TODAY THROUGH WEDNESDAY NIGHT/ MODELS ARE IN GOOD AGREEMENT FOR THE PERIOD. A MID/UPPER LEVEL LOW CROSSING THE LOWER MISSISSIPPI VALLEY ON MONDAY NIGHT WAS BEING ABSORBED BACK INTO THE PREVAILING WESTERLIES AS A NORTHERN STREAM TROUGH DROPPED SE TOWARD THE GREAT LAKES. THIS IS RESULTING IN A DEEPENING SURFACE LOW OVER WEST TN WHICH WILL MOVE NE ACROSS KY. THE SYSTEM HAS A DEEP MOISTURE TAP...WITH RAIN HAVING OVERSPREAD THE AREA DURING THE NIGHT. A DRY SLOT WRAPPING NORTHWARD INTO THE SYSTEM WILL TRY TO MOVE N INTO KY TODAY...BRINGING A DIMINISHING TREND IN RAIN... ESPECIALLY FOR OUR SOUTHERN AND SOUTHEASTERN COUNTIES LATE THIS MORNING AND EARLY THIS AFTERNOON. THE TAIL OF THE COMMA HEAD WILL MOVE EAST ACROSS THE AREA THIS AFTERNOON. IT WILL BRING ANOTHER INCREASE IN PRECIP...ESPECIALLY FOR OUR NORTHERN AND EASTERN COUNTIES. THIS PRECIP WILL BE MUCH LIGHTER THAN THAT OF THE MORNING. WITH COLDER AIR ARRIVING ON THE BACK SIDE OF THE SURFACE LOW...THE RAIN WILL MIX WITH OR CHANGE TO SNOW FROM NW TO SE DURING THE LATE AFTERNOON AND EVENING. COLDER AIR ALOFT WILL SUPPORT A SURFACE CHANGEOVER TEMPERATURE IN THE MID 30S. WILL EXPECT PRECIP TO TAPER OFF BEFORE TEMPS FALL BELOW FREEZING IN MOST LOCATIONS...PREVENTING SIGNIFICANT SNOW ACCUMULATIONS. A POSSIBLE EXCEPTION WILL BE ELEVATIONS ABOVE ABOUT 2000 FEET NEAR THE VA BORDER...AND WILL CALL FOR A POSSIBILITY OF 1-2 INCHES THERE TONIGHT. MUCH DRIER AIR SHOULD ARRIVE BY WEDNESDAY MORNING...WITH DRY WEATHER AND MAINLY CLEAR SKIES FORECAST FOR WEDNESDAY AND WEDNESDAY NIGHT. HIGH PRESSURE WILL BUILD IN FROM THE WEST ON WEDNESDAY...WITH THE RIDGE MOVING TO OUR EAST ON WEDNESDAY NIGHT. THE RETURN OF WARM AIR ADVECTION ON THE BACK SIDE OF THE HIGH ON WEDNESDAY NIGHT WILL PROMOTE RIDGE/VALLEY LOW TEMPERATURE DIFFERENCES. .LONG TERM.../THURSDAY THROUGH MONDAY/ THE EXTENDED FORECAST BEGINS ON THURSDAY WITH A PROGRESSIVE PATTERN IN PLACE AND A BROAD TROUGH OVER THE EASTERN US. THE MAIN CONCERN COMES IN THE FRIDAY TO SATURDAY PERIOD IN THE FORM OF A COUPLE OF ALBERTA CLIPPER TYPE LOWS IN NORTHWEST FLOW. BOTH THE GFS AND EURO ARE AGREEING WITH THE STRENGTH AND POSITIONING OF THE DISTURBANCE BUT ARE DIVIDED ON THE TIMING. QPF WITH THIS SYSTEM IS MINIMAL AT BEST...ESPECIALLY WITH ITS CONTINENTAL ORIGIN. AT THIS POINT...SNOW SEEMS A BIT FAR FETCHED AS BOTH THE EURO AND GFS DO NOT SHOW ANY SIGNIFICANT COLD AIR IN PLACE AND EVEN ON THE BACK SIDE OF THE SYSTEM. THEREFORE...WILL LIKELY THROW IN AT LEAST SOME SLIGHT CHANCE POPS ON FRIDAY AND INTO SATURDAY. THE ONLY OTHER CONCERN IS A STRONGER WAVE DEVELOPING AND MOVING THROUGH SUNDAY NIGHT AND INTO MONDAY. THE DIFFERENCES WITH THE EURO AND GFS WITH THIS IS TIMING AS THE GFS IS 24 HOURS FASTER AND WEAKER THAN THE EURO WITH A SLOWER AND MORE AMPLIFIED PATTERN. THE EURO DEVELOPS A SHARP TROUGH DIGGING FROM THE GREAT LAKES TO THE GULF COAST...ALLOWING BITTERLY COLD AIR INTO THE EAST COAST. FOR NOW THE GFS AND GEM STICK TO THE GFS ENSEMBLE. WILL STICK TO THE FAST GFS SOLUTION...ESPECIALLY WITH THE PROGRESSIVE PATTERN IN PLACE DURING THE BEGINNING OF THE EXTENDED. AFTER INITIALIZATION AND THE 00Z EURO STICKING TO A SLOWER AMPLIFIED PATTERN FOR THE MON TO TUE TIME FRAME. THE INITIALIZATION DID LEAN TO THE EURO A BIT BUT THIS IS THE 12Z RUN. WITH THE EURO SHOWING SOME RUN TO RUN CONSISTENCY WITH THIS AND DEVELOPING A VIGOROUS COASTAL LOW ON THE MON THROUGH WED TIME FRAME...WILL HAVE TO WATCH TO SEE IF THE OTHER OPERATIONAL MODELS SHIFT TO THIS SOLUTION. THE OTHER PIECE OF INFORMATION IS WHAT THE NAO IS SHOWING AND WHILE ITS ENSEMBLE MEMBERS DO SHOW SOME DIFFERENT SOLUTIONS...A INDICATION OF A MORE PROGRESSIVE PATTERN AND LESS BLOCKING IS SHOWN THROUGH JAN 1ST...SOME OF THE MEMBERS DO DIP INTO THE NEGATIVE RANGE BY THE 3RD INDICATING A MORE AMPLIFIED PATTERN. THEREFORE...FOR THE FORECAST WILL CLEAR OUT POPS BY MONDAY ACCORDING TO THE GFS SOLUTION BUT THE EURO SOLUTION AS WELL AS THE ENSEMBLES WILL NEED SOME MONITORING. && .AVIATION.../18Z TO 18Z/...UPDATED SOUTHWEST WINDS WILL BRIEFLY GUST TO 30 TO 35 KNOTS THIS AFTERNOON. SURFACE LOW PRESSURE HAS MOVED INTO WESTERN OH. A LOW PRESSURE TROF SWINGING NORTHEAST THROUGH THE AREA IS BRINGING WIDESPREAD RAIN AND MVFR TO IFR CONDITIONS. GUSTY WINDS ARE OCCURRING IN A SMALL PRECIPITATION FREE AREA BETWEEN THE PRIMARY RAIN SHIELD AND THE WRAP AROUND PRECIPITATION NOW MOVING ACROSS CENTRAL KY. WHILE THE MAIN PRECIPITATION SHIELD IS CURRENTLY EXITING EASTERN KY...THERE IS CONSIDERABLE WRAP AROUND MOISTURE SO PERIODS OF RAIN WILL CONTINUE THROUGH THE AFTERNOON WITH GENERALLY MVFR CEILINGS...AND SOME LOCAL IFR CONDITIONS. RAIN WILL MIX WITH OR CHANGE TO LIGHT SNOW FOR A TIME TONIGHT AS COLDER AIR WRAPS AROUND THE EXITING LOW PRESSURE SYSTEM. MVFR CEILINGS ARE EXPECTED TO PREVAIL LATE TONIGHT INTO WEDNESDAY. && .JKL WATCHES/WARNINGS/ADVISORIES...NONE. && $$ SHORT TERM...HAL/SBH LONG TERM....SHALLENBERGER AVIATION...SBH
AREA FORECAST DISCUSSION
NWS PITTSBURGH PA
408 PM EST TUE DEC 27 2011 .SYNOPSIS... A LOW PRESSURE SYSTEM WILL CROSS THE AREA, SPREADING MOSTLY RAIN OVER THE UPPER OHIO VALLEY REGION TODAY BEFORE PRECIPITATION CHANGES TO ALL SNOW TONIGHT. HIGH PRESSURE WILL THEN BUILD IN FOR A DRY MID- WEEK. && .NEAR TERM /UNTIL 6 AM WEDNESDAY MORNING/... THE LATEST RUC MID-LEVEL ANALYSIS INDICATES TWO TROUGH FEATURES THAT ARE SLIGHTLY OFF IN TIMING AND PHASING. THE NORTHERN AND SLOWER FEATURE IS LOCATED ACROSS LAKE MICHIGAN WITH THE SOUTHERN BRANCH ALONG ACROSS WESTERN PENNSYLVANIA. AN 850MB CLOSED LOW IS LOCATED ACROSS NORTH-CENTRAL OHIO. AHEAD OF THIS FEATURE, A WARM WEDGE OF 850 TEMPS AT 1-3C IS BEGINNING TO EDGE EASTWARD OUT THE AREA INTO CENTRAL PA WITH 0C TO -2C 850 TEMPS ENCROACHING EASTERN OHIO. THE WEDGE HAS HELD MOST OF THE DAY WITH RAIN BEING THE DOMINANT TYPE OF PRECIP ACROSS THE AREA. THERE HAS HOWEVER BEEN A MIX ALONG THE I-80 CORRIDOR. AT THE SURFACE A 994MB LOW IS LOCATED ACROSS LAKE ERIE WITH A WIND SHIFT TO NORTHWESTERLY BEHIND IT. ON THE BACK-SIDE OF THE LOW, A DEFORMATION ZONE WITH MODERATE SNOW IS WEAKENING AS IT MOVES INTO WESTERN OHIO. THIS EVENING...THE NORTHERN AND SOUTHERN BRANCHES WILL ATTEMPT TO PHASE INTO A MID-LEVEL TROUGH WITH THE SURFACE LOW MOVING INTO WESTERN NY. THE 850MB LOW WILL PASS NORTHEAST OF THE AREA, WRAPPING COLDER AIR IN BEHIND IT. IN ADDITION, RUC/NAM HINT AT THE RE- DEVELOPMENT OF A 700MB DEFORMATION ZONE, WHICH WILL BRING A SHOT OF MODERATE SNOW TO THE AREA THIS EVENING. THE MOST UNCERTAINTY IN THE FORECAST LIES IN REGARDS TO WHETHER THE DEFORMATION ZONE WILL CONTINUE TO WEAKEN OR RE-DEVELOP. HAVE SIDED WITH IT RE- DEVELOPING. AS SURFACE WINDS SHIFT TO NORTHWESTERLY, THE CHANGEOVER TO SNOW WILL QUICKLY ENSUE. TEMPS WILL REMAIN MID 40S IN LOCATIONS WEST OF CHESTNUT RIDGE WHERE DOWNSLOPING IS OCCURRING. OTHERWISE, TEMPS WILL RANGE FROM THE MID 30S ACROSS THE I-80 CORRIDOR TO THE LOWER 40S ACROSS NORTH-CENTRAL WV. THE COLDEST AIR REMAINS TRAPPED IN THE VALLEYS OF GARRETT COUNTY, WHERE TEMPS IN THE LOWER TO MID 30S WILL ALLOW FOR SOME SLEET TO MIX IN WITH RAIN. WILL CONTINUE TO MONITOR THIS AREA FOR FREEZING RAIN BEFORE THE TURN OVER TO SNOW. TONIGHT...THE TROUGH AND SURFACE LOW WILL SHIFT NORTHEAST OF THE AREA INTO NEW YORK, WITH COLD AIR ADVECTION ALLOWING FOR PRECIPITATION TO QUICKLY TURN OVER TO ALL SNOW. THE 700MB DEFORMATION ZONE WILL CROSS THE AREA, ALLOWING FOR AN INITIAL QUICK BURST OF A HALF OF AN INCH TO AN INCH ACROSS MUCH OF THE AREA. HAVE ISSUED AN SPS TO HIGHLIGHT THIS FEATURE. AFTER THE INITIAL BURST, A NORTHWESTERLY FLOW WILL ALLOW FOR SNOW SHOWERS ACROSS THE AREA. UPSLOPING ACROSS THE RIDGES ALONG WITH A SLIGHTLY FASTER CHANGEOVER FOR AREAS NORTH OF PITTSBURGH WILL ALLOW FOR 2 TO 4 INCHES BY DAWN ON WEDNESDAY. OVERNIGHT LOWS ARE CLOSER TO LAMP GUIDANCE, RANGING FROM THE MID TO UPPER 20S ACROSS THE AREA. THE QUICK DROP BELOW FREEZING BY MIDNIGHT, WILL LEAD TO SOME ICY AND SNOW-COVERED ROADS THROUGH DAWN. && .SHORT TERM /6 AM WEDNESDAY MORNING THROUGH FRIDAY/... LAKE EFFECT SNOW SHOWERS WILL LINGER EARLY ON WEDNESDAY, ALTHOUGH DO NOT EXPECT ACCUMULATIONS TO AMOUNT TO MORE THAN AN INCH WITH LOWERED INVERSION HEIGHTS LIMITING INSTABILITY. A SURFACE HIGH WILL THEN BUILD IN THROUGH THURSDAY. TEMPERATURES WILL BE AROUND 5 DEGREES BELOW NORMAL ON WEDNESDAY AND WEDNESDAY NIGHT AS ARCTIC AIR SETTLES INTO THE AREA IN THE WAKE OF THE LOW. THERE IS SOME UNCERTAINTY IN TIMING OF A SERIES OF SHORT WAVES CROSSING THE AERA THURSDAY INTO FRIDAY. SCHC POPS ARE INTRODUCED NORTH OF PITTSBURGH ON THURSDAY, INCREASING TO CHANCE THURSDAY NIGHT, WITH THE BEST CHANCE ON FRIDAY AS A MORE PRONOUNCED TROUGH AXIS CROSSES THE AREA. MODEL THICKNESSES INDICATE A MIX OF RAIN AND SNOW SHOWERS FOR THE AREA, SO DO NOT ANTICIPATE ANY SIGNIFICANT ACCUMULATIONS WITH THE WAVES AS THEY MOVE THROUGH. TEMPS WILL BE AROUND 5 DEGREES ABOVE SEASONAL NORMALS THURSDAY INTO FRIDAY. && .LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/... FAST MOVING SYSTEMS IN A PROGRESSIVE FLOW WILL BRING TEMPERATURES AVERAGING CLOSE TO NORMAL AND CHANCES FOR RAIN OR SNOW SHOWERS FOR LATE WEEK INTO THE WEEKEND. STRONGER DISTURBANCE WILL TAP INTO THE NORTHERN BRANCH OF THE JET STREAM BRINGING PROGRESSIVELY COLDER AIR INTO THE REGION BY TUESDAY NIGHT. && .AVIATION /21Z TUESDAY THROUGH SUNDAY/... IFR CONDITIONS WITH LIFR IN AREAS SOUTH OF PITTSBURGH AS LOW LEVEL MOISTURE IS TRAPPED UNDER THE INVERSION. LLWS ALL TAF SITES AS H8 LOW LEVEL JET AT MGW OFF THE NAM AT 2PM INDICATES 81KT JET. WIND SHIFT LINE AND CHANGE OVER TO SNOW IS OVER WESTERN OHIO NOW IN THE VCNTY OF KDAY. LOW IS DEEPENING RAPIDLY AND THAT WIND SHIFT AND CHANGE OVER TO SNOW LINE WILL REACH CWA 23Z VCNTY THROUGH 02Z IFR CAN BE EXPECTED INTO TUESDAY NIGHT AS PRECIPITATION TRANSITIONS TO SNOW IN THE COLD ADVECTION ON THE WRN SIDE OF THE EXITING LOW. CIGS MAY IMPROVE DURING THE OVRNGT TO MVFR LEVELS...BUT IFR VISIBILITY IN SNOW SHOWERS SHOULD CONTINUE. OUTLOOK...WEDNESDAY THROUGH SUNDAY... CONDITIONS SHOULD GRADUALLY IMPROVE TO VFR BY LATE WEDNESDAY AS A WEAK SURFACE RIDGE MOVES EAST. A SERIES OF FAST MOVING WEATHER SYSTEMS WILL THEN CROSS THE REGION DURING THE LATTER HALF OF THE WEEK WITH PERIODIC RESTRICTIONS. && .PBZ WATCHES/WARNINGS/ADVISORIES... MD...WINTER WEATHER ADVISORY FROM 7 PM THIS EVENING TO 4 AM EST WEDNESDAY FOR MDZ001. OH...WINTER WEATHER ADVISORY UNTIL 4 AM EST WEDNESDAY FOR OHZ041. PA...WINTER WEATHER ADVISORY UNTIL 4 AM EST WEDNESDAY FOR PAZ007>009-013-015-016. WINTER WEATHER ADVISORY FROM 7 PM THIS EVENING TO 4 AM EST WEDNESDAY FOR PAZ014-020>023-073>076. WV...WINTER WEATHER ADVISORY FROM 7 PM THIS EVENING TO 4 AM EST WEDNESDAY FOR WVZ023-041. && $$
AREA FORECAST DISCUSSION
NWS PITTSBURGH PA
205 PM EST TUE DEC 27 2011 .SYNOPSIS... A LOW PRESSURE SYSTEM WILL CROSS THE AREA, SPREADING MOSTLY RAIN OVER THE UPPER OHIO VALLEY REGION TODAY BEFORE PRECIPITATION CHANGES TO ALL SNOW TONIGHT. HIGH PRESSURE WILL THEN BUILD IN FOR A DRY MID- WEEK. && .NEAR TERM /THROUGH 8 PM THIS EVENING/... THE EARLY AFTERNOON UPDATE HAS BEEN ISSUED TO ACCOUNT FOR RECENT TRENDS IN TEMPS AND TO ADD A MIX OF SLEET WITH RAIN FOR GARRETT COUNTY IN MARYLAND. THE LATEST RUC MID-LEVEL ANALYSIS INDICATES TWO TROUGH FEATURES THAT ARE TRYING TO PHASE. THE NORTHERN FEATURE IS LOCATED ACROSS THE UPPER MIDWEST WITH THE SOUTHERN BRANCH ALONG THE OHIO/WEST VIRGINIA BORDER. AN 850MB CLOSED LOW IS LOCATED ACROSS NORTHWEST OHIO. AHEAD OF THIS FEATURE, A WARM WEDGE OF 850 TEMPS AT 2-5C HAS MOVED INTO WESTERN PENNSYLVANIA. THIS HAS ALLOWED PRECIPITATION TO TURN TO MOSTLY RAIN ACROSS THE AREA. THERE HAS HOWEVER BEEN A MIX ALONG THE I-80 CORRIDOR. LAPS ANALYSIS INDICATES THE WET BULB ZERO LINE ACROSS FOREST COUNTY. WET BULBING IN THIS AREA HAS LEAD TO A MIX OF SNOW AND SLEET BEFORE PRECIPITATION TURNS OVER TO RAIN BRIEFLY THIS AFTERNOON. AT THE SURFACE A 997MB LOW IS LOCATED NEAR LIMA, OHIO WITH A WIND SHIFT TO NORTHWESTERLY BEHIND IT. ON THE BACK-SIDE OF THE LOW, A DEFORMATION ZONE HAS DEVELOPED WITH SOME AREAS OF MODERATE SNOW IN INDIANA AND WESTERN OHIO. THIS AFTERNOON...THE NORTHERN AND SOUTHERN BRANCHES WILL ATTEMPT TO PHASE INTO A MID-LEVEL TROUGH WITH THE SURFACE LOW MOVING INTO NORTHWEST PENNSYLVANIA. THE 850MB LOW WILL PASS NORTHEAST OF THE AREA, WRAPPING COLDER AIR IN BEHIND IT. IN ADDITION, RUC/NAM ARE SHOWING 700MB DEFORMATION ZONE SHIFTING ACROSS THE OHIO VALLEY AND BRINGING A SHOT OF MODERATE SNOW TO EASTERN OHIO BY THIS EVENING. AS SURFACE WINDS SHIFT TO NORTHWESTERLY, THE CHANGEOVER TO SNOW WILL QUICKLY ENSUE. TEMPS WILL REMAIN MID 40S IN LOCATIONS WEST OF CHESTNUT RIDGE WHERE DOWNSLOPING IS OCCURRING. OTHERWISE, TEMPS WILL RANGE FROM THE MID 30S ACROSS THE I-80 CORRIDOR TO THE LOWER 40S ACROSS NORTH-CENTRAL WV. THE COLDEST AIR REMAINS TRAPPED IN THE VALLEYS OF GARRETT COUNTY, WHERE TEMPS IN THE LOWER 30S WILL ALLOW FOR SOME SLEET TO MIX IN WITH RAIN. WILL CONTINUE TO MONITOR THIS AREA FOR FREEZING RAIN BEFORE THE TURN OVER TO SNOW. && .SHORT TERM /TONIGHT THROUGH THURSDAY/... THE TROUGH AND SURFACE LOW WILL SHIFT NORTHEAST OF THE AREA INTO NEW YORK, WITH COLD AIR ADVECTION ALLOWING FOR PRECIPITATION TO QUICKLY TURN OVER TO ALL SNOW. A 700MB DEFORMATION ZONE WILL CROSS THE AREA, ALLOWING FOR AN INITIAL QUICK BURST OF 1 TO 2 INCHES ACROSS MUCH OF THE AREA. AFTER THE INITIAL BURST, A NORTHWESTERLY FLOW WILL ALLOW FOR SNOW SHOWERS ACROSS THE AREA. UPSLOPING ACROSS THE RIDGES ALONG WITH A SLIGHTLY FASTER CHANGEOVER AND SOME LAKE ENHANCEMENT FOR AREAS NORTH OF PITTSBURGH WILL ALLOW FOR 2 TO 4 INCHES BY DAWN ON WEDNESDAY. OVERNIGHT LOWS ARE CLOSE TO LAMP GUIDANCE, RANGING FROM THE MID TO UPPER 20S ACROSS THE AREA. THE QUICK DROP BELOW FREEZING BY MIDNIGHT, WILL LEAD TO SOME ICY AND SNOW-COVERED ROADS THROUGH DAWN. LAKE EFFECT SNOW SHOWERS WILL LINGER EARLY ON WEDNESDAY, ALTHOUGH DO NOT EXPECT ACCUMULATIONS TO AMOUNT TO MORE THAN AN INCH WITH LOWERED INVERSION HEIGHTS LIMITING INSTABILITY. A SURFACE HIGH WILL THEN BUILD IN THROUGH THURSDAY. TEMPERATURES WILL BE BELOW NORMAL BUT CONDITIONS SHOULD BE DRY. && .LONG TERM /THURSDAY NIGHT THROUGH TUESDAY/... FAST MOVING SYSTEMS IN PROGRESSIVE FLOW WILL BRING TEMPERATURES AVERAGING ABOVE NORMAL AND CHANCES FOR RAIN OR SNOW SHOWERS FOR LATE WEEK INTO THE WEEKEND. LONG TERM PERIOD WAS FORECAST CLOSE TO HPC PROGS WHICH CONTINUE TO TREND TOWARD THE ECMWF. && .AVIATION /19Z TUESDAY THROUGH SUNDAY/... IFR CONDITIONS WITH LIFR IN AREAS SOUTH OF PITTSBURGH AS LOW LEVEL MOISTURE IS TRAPPED UNDER THE INVERSION. LLWS ALL TAF SITES AS H8 LOW LEVEL JET AT MGW OFF THE NAM AT 2PM INDICATES 81KT JET. WIND SHIFT LINE AND CHANGE OVER TO SNOW IS OVER WESTERN OHIO NOW IN THE VCNTY OF KDAY. LOW IS DEEPENING RAPIDLY AND THAT WIND SHIFT AND CHANGE OVER TO SNOW LINE WILL REACH CWA 23Z VCNTY THROUGH 02Z IFR CAN BE EXPECTED INTO TUESDAY NIGHT AS PRECIPITATION TRANSITIONS TO SNOW IN THE COLD ADVECTION ON THE WRN SIDE OF THE EXITING LOW. CIGS MAY IMPROVE DURING THE OVRNGT TO MVFR LEVELS...BUT IFR VISIBILITY IN SNOW SHOWERS SHOULD CONTINUE. OUTLOOK...WEDNESDAY THROUGH SUNDAY... CONDITIONS SHOULD GRADUALLY IMPROVE TO VFR BY LATE WEDNESDAY AS A WEAK SURFACE RIDGE MOVES EAST. A SERIES OF FAST MOVING WEATHER SYSTEMS WILL THEN CROSS THE REGION DURING THE LATTER HALF OF THE WEEK WITH PERIODIC RESTRICTIONS. && .PBZ WATCHES/WARNINGS/ADVISORIES... MD...WINTER WEATHER ADVISORY FROM 7 PM THIS EVENING TO 4 AM EST WEDNESDAY FOR MDZ001. OH...WINTER WEATHER ADVISORY UNTIL 4 AM EST WEDNESDAY FOR OHZ041. PA...WINTER WEATHER ADVISORY UNTIL 4 AM EST WEDNESDAY FOR PAZ007>009-013-015-016. WINTER WEATHER ADVISORY FROM 7 PM THIS EVENING TO 4 AM EST WEDNESDAY FOR PAZ014-020>023-073>076. WV...WINTER WEATHER ADVISORY FROM 7 PM THIS EVENING TO 4 AM EST WEDNESDAY FOR WVZ023-041. && $$
AREA FORECAST DISCUSSION
NWS PITTSBURGH PA
1127 AM EST TUE DEC 27 2011 .SYNOPSIS... A LOW PRESSURE SYSTEM WILL CROSS THE AREA, SPREADING A WINTRY MIX OVER THE UPPER OHIO VALLEY REGION TODAY AND THEN ALL SNOW TONIGHT. HIGH PRESSURE WILL THEN BUILD IN FOR A DRY MID-WEEK. && .NEAR TERM /UNTIL 8 PM THIS EVENING/... A LATE MORNING UPDATE HAS BEEN ISSUED TO ADD A SNOW/SLEET MIX TO THE I-80 CORRIDOR AND TO MOVE UP CHANGEOVER TO SNOW BY A FEW HOURS EARLIER AS TEMPS ARE TRENDING COLDER. THE LATEST RUC MID-LEVEL ANALYSIS INDICATES TWO TROUGH FEATURES THAT ARE ATTEMPTING TO PHASE. THE NORTHERN FEATURE IS LOCATED ACROSS THE UPPER MIDWEST WITH THE SOUTHERN BRANCH CROSSING THE TENNESSEE VALLEY. AN 850MB CLOSED LOW HAS DEVELOPED ACROSS INDIANA. AHEAD OF THIS FEATURE, A WARM WEDGE OF 850 TEMPS AT 2-4C HAS MOVED INTO WESTERN PENNSYLVANIA. THIS HAS ALLOWED PRECIPITATION TO TURN TO MOSTLY RAIN ACROSS THE AREA. THERE HAS HOWEVER BEEN A MIX NORTH OF PITTSBURGH. LAPS ANALYSIS INDICATES THE WET BULB ZERO LINE ACROSS THE I-80 CORRIDOR. WET BULBING IN THIS AREA HAS LEAD TO A MIX OF SNOW AND SLEET BEFORE PRECIPITATION TURNS OVER TO RAIN BRIEFLY THIS AFTERNOON. AT THE SURFACE A 999MB LOW IS LOCATED NEAR CINCINNATI, OHIO, WITH A WIND SHIFT TO NORTHWESTERLY BEHIND IT. ON THE BACK-SIDE OF THE LOW, A DEFORMATION ZONE HAS DEVELOPED WITH SOME AREAS OF MODERATE SNOW IN INDIANA. THIS AFTERNOON...THE NORTHERN AND SOUTHERN BRANCHES WILL PHASE INTO A MID-LEVEL TROUGH WITH THE SURFACE LOW MOVING INTO THE NORTHWEST PENNSYLVANIA. EARLY THIS AFTERNOON, WET BULB ZERO LINE WILL CONTINUE TO ALLOW FOR SLEET AND SNOW TO MIX IN, ALTHOUGH NO ACCUMULATION IS EXPECTED WITH TEMPS ABOVE FREEZING. A RAIN/SNOW MIX WILL LINGER THERE UNTIL PRECIP TURNS TO SNOW LATER THIS AFTERNOON. THE 850MB LOW WILL PASS NORTHEAST OF THE AREA, WRAPPING COLDER AIR IN BEHIND IT. IN ADDITION, RUC/NAM ARE SHOWING 700MB DEFORMATION ZONE SHIFTING ACROSS THE OHIO VALLEY AND BRINGING A SHOT OF MODERATE SNOW TO EASTERN OHIO BY THE EARLY EVENING. AS SURFACE WINDS SHIFT TO NORTHWESTERLY, THE CHANGEOVER TO SNOW WILL QUICKLY ENSUE. WITH RECENT TRENDS IN OBS, THIS CHANGEOVER HAS BEEN MOVED UP A FEW HOURS. TEMPS WILL RANGE FROM THE MID 40S ACROSS NORTH- CENTRAL WV TO THE MID 3OS ACROSS THE I-80 CORRIDOR AND REMAIN FAIRLY STEADY UNTIL THE WIND SHIFT OCCUR LATE THIS AFTERNOON IN THE EARLY EVENING. && .SHORT TERM /8 PM THIS EVENING THROUGH THURSDAY/... THE TROUGH AND SURFACE LOW WILL SHIFT NORTHEAST OF THE AREA INTO NEW YORK, WITH COLD AIR ADVECTION ALLOWING FOR PRECIPITATION TO QUICKLY TURN OVER TO ALL SNOW. A 700MB DEFORMATION ZONE WILL CROSS THE AREA, ALLOWING FOR AN INITIAL QUICK BURST OF 1 TO 2 INCHES ACROSS MUCH OF THE AERA. AFTER THE INITIAL BURST, A NORTHWESTERLY FLOW WILL ALLOW FOR SNOW SHOWERS ACROSS THE AREA. UPSLOPING ACROSS THE RIDGES ALONG WITH A SLIGHTLY FASTER CHANGEOVER AND SOME LAKE ENHANCEMENT FOR AREAS NORTH OF PITTSBURGH WILL ALLOW FOR 2 TO 4 INCHES BY DAWN ON WEDNESDAY. OVERNIGHT LOWS ARE CLOSE TO LAMP GUIDANCE, RANGING FROM THE MID TO UPPER 20S ACROSS THE AREA. THE QUICK DROP BELOW FREEZING BY MIDNIGHT, WILL LEAD TO SOME ICY AND SNOW-COVERED ROADS THROUGH DAWN. LAKE EFFECT SNOW SHOWERS WILL LINGER EARLY ON WEDNESDAY, ALTHOUGH DO NOT EXPECT ACCUMULATIONS TO AMOUNT TO MORE THAN AN INCH WITH LOWERED INVERSION HEIGHTS LIMITING INSTABILITY. A SURFACE HIGH WILL THEN BUILD IN THROUGH THURSDAY. TEMPERATURES WILL BE BELOW NORMAL BUT CONDITIONS SHOULD BE DRY. && .LONG TERM /THURSDAY NIGHT THROUGH MONDAY/... FAST MOVING SYSTEMS IN PROGRESSIVE FLOW WILL BRING TEMPERATURES AVERAGING ABOVE NORMAL AND CHANCES FOR RAIN OR SNOW SHOWERS FOR LATE WEEK INTO THE WEEKEND. LONG TERM PERIOD WAS FORECAST CLOSE TO HPC PROGS WHICH CONTINUE TO TREND TOWARD THE ECMWF. && .AVIATION /16Z TUESDAY THROUGH SATURDAY/... VFR CONDITIONS CAN BE EXPECTED IN THE IMMEDIATE POST DAWN ALTHOUGH CLOUD LEVEL WILL BE STEADILY LOWERING AS MOISTURE BEING PUSHED IN ADVANCE OF APPROACHING LOW PRES OVERCOMES DEEP DRY LAYER OVR THE UPR OHIO REGION. CONFIDENCE IS HIGH THAT CONDITIONS WILL DETERIORATE TO IFR BY MIDDAY AS THAT LOW CONTS A NEWD TREK AND THE UPR OHIO VALLEY ATMOSPHERE SATURATES. PROJECTED PASSAGE OF THE LOW ACRS OHIO WOULD ENSURE THAT WARM ADVECTION ON THE ERN FLANK OF THAT SYSTEM WILL CHANGE ANY MIXED PRECIP AT KDUJ/KFKL BRIEFLY TO RAIN THIS AFTERNOON BEFORE PRECIP TURNS BACK OVER TO ALL SNOW. OTHER CONCERN FOR THE MIDDAY PERIOD WL BE THE LLWS POTENTIAL AS WIND SPEED ABOVE THE BOUNDARY LAYER WL INCRS SIGNIFICANTLY WITH PASSAGE OF THE LOW. CONFIDENCE IN THAT POTENTIAL IS SUFFICIENTLY HIGH TO INCLUDE IN ALL TAFS. IFR CAN BE EXPECTED INTO TUESDAY NIGHT AS PRECIPITATION TRANSITIONS TO SNOW IN THE COLD ADVECTION ON THE WRN SIDE OF THE EXITING LOW. CIGS MAY IMPROVE DURING THE OVRNGT TO MVFR LEVELS...BUT IFR VISIBILITY IN SNOW SHOWERS SHOULD CONT TO PLAGUE AREA PORTS. OUTLOOK...WEDNESDAY THROUGH SATURDAY... CONDITIONS SHOULD GRADUALLY IMPROVE TO VFR BY LATE WEDNESDAY AS A WEAK SURFACE RIDGE MOVES EAST. A SERIES OF FAST MOVING WEATHER SYSTEMS WILL THEN CROSS THE REGION DURING THE LATTER HALF OF THE WEEK WITH PERIODIC RESTRICTIONS. && .PBZ WATCHES/WARNINGS/ADVISORIES... MD...WINTER WEATHER ADVISORY FROM 7 PM THIS EVENING TO 4 AM EST WEDNESDAY FOR MDZ001. OH...WINTER WEATHER ADVISORY FROM 4 PM THIS AFTERNOON TO 4 AM EST WEDNESDAY FOR OHZ041. PA...WINTER WEATHER ADVISORY FROM 4 PM THIS AFTERNOON TO 4 AM EST WEDNESDAY FOR PAZ007>009-013-015-016. WINTER WEATHER ADVISORY FROM 7 PM THIS EVENING TO 4 AM EST WEDNESDAY FOR PAZ014-020>023-073>076. WV...WINTER WEATHER ADVISORY FROM 7 PM THIS EVENING TO 4 AM EST WEDNESDAY FOR WVZ023-041. && $$
AREA FORECAST DISCUSSION
NWS GRAND RAPIDS MI
1242 PM EST TUE DEC 27 2011 LATEST UPDATE...AVIATION... .SYNOPSIS...(450 AM EST TUE DEC 27 2011) LOW PRESSURE MOVING NORTH FROM THE SOUTHERN US WILL COMBINE WITH COLDER AIR MOVING SOUTH FROM CANADA TO PRODUCE SOME LIGHT SNOW TODAY. LIGHT RAIN MAY MIX WITH THE SNOW...ESPECIALLY THIS MORNING. AN INCH OR TWO OF ACCUMULATION IS POSSIBLE WITH GREATEST AMOUNTS SOUTHEAST OF A KALAMAZOO TO LANSING LINE. WEDNESDAY WILL BE OUR COLDEST DAY WITH HIGHS AROUND 30. AFTER THAT HIGHS WILL CLIMB TO NEAR 40 THROUGH THE WEEKEND. A CLIPPER SYSTEM WILL BRING A CHANCE OF RAIN AND SNOW TO THE REGION THURSDAY. && .SHORT TERM...(1115 AM EST TUE DEC 27 2011) (TODAY THROUGH THURSDAY) * ACCUMULATING SNOW WILL TAPER TO FLURRIES/LIGHT RAIN EARLY THIS AFTERNOON WITH SNOW TOTALS OF 1 TO 3 INCHES...PRIMARILY GRASSY SURFACES...SIGNIFICANT WEATHER ADVISORY WAS ISSUED AT 10 AM. * GUSTY WINDS ALONG COAST THIS EVENING WILL BE LOOKING AT POSSIBLE WIND ADVISORY FOR THE COAST... RADAR INDICATING TWO BANDS OF MODERATE SNOW AT THE PRESENT TIME. BOTH ARE ORIENTED SSW-NNE WITH ONE FROM KGRR TO KMOP...WITH THE SECOND BAND ALONG A KOEB...KJXN...KFNT LINE. BOTH BANDS ARE SLOWLY MOVING EAST AND ARE EXPECTED TO WEAKEN AS THE MIDLEVEL FRONTOGENESIS SHIFT TO THE NORTHEAST AND SURFACE COLD FRONT SWEEPS EASTWARD THIS AFTERNOON. THE HRRR RUC HAS HAD A REALLY GOOD HANDLE ON THE EVOLUTION OF THE SYSTEM THIS MORNING AND HAVE LEVERAGED IT HEAVILY IN UPDATING SNOWFALL GRIDS. ALTHOUGH...HALF OF THE SNOW HAS FALLEN...LOOKS LIKE LOCAL TOTALS OF 3 INCHES ARE LIKELY. TEMPERATURES ARE EXPECTED TO RISE INTO THE MID 30S THIS AFTERNOON AS THE SNOW TAPERS OFF AND MAY EVEN END AS A MIX WITH RAIN BEFORE ENDING. THIS EVENING WINDS WILL KICK UP AS COLDER AIR FLOWS IN BEHIND THE LOW AS IT MOVES BY TO THE SOUTHEAST. STRONGEST WINDS WILL BE NEAR THE LAKE SHORE. PCPN WILL DIMINISH THIS EVENING. THERE MAY BE A FEW SNOW SHOWERS ALONG THE LAKE SHORE IN NORTH FLOW AS H8 TEMPS FALL BRIEFLY TO AROUND -12C. MOISTURE IS SHALLOW THOUGH AND NOTHING ORGANIZED IS EXPECTED. THE NEXT CLIPPER WILL MOVE TOWARD THE REGION WEDNESDAY NIGHT AND THURSDAY. AS HAS BEEN TYPICAL LATELY...THIS SYSTEM WILL SCOOT BY TO THE NORTH. THAT MEANS WE/LL SEE SOME WARMER AIR FLOW INTO THE CWA AND MIXED RAIN/SNOW IS EXPECTED IN THE SRN CWA WITH MORE SNOW IN THE NORTH. APPRECIABLE ACCUMS ARE NOT EXPECTED. && .LONG TERM...(450 AM EST TUE DEC 27 2011) (THURSDAY NIGHT THROUGH MONDAY) ZONAL FLOW IS FORECAST TO CONTINUE OVER THE LOWER 48 FOR MUCH OF THE LONG TERM...TRANSITIONING TO AN EASTERN TROUGH/WESTERN RIDGE TOWARD THE END OF THE PERIOD. GENERALLY LIGHT PRECIPITATION IS EXPECTED THROUGH THE PERIOD. TIMING ISSUES ARE ALWAYS A CONCERN IN ZONAL FLOW AND THIS FORECAST IS NO EXCEPTION. FIRST WEAK SHORTWAVE TO DEAL WITH IS MOVING THROUGH THE GREAT LAKES THURSDAY NIGHT. LOOKS LIKE MAINLY LIGHT SNOW...WITH QPF TOTALS THAT ARE ON THE ORDER OF 0.10 OR LESS...SO NO ISSUES EXPECTED. THE EUROPEAN HAS ANOTHER WAVE AFFECTING THE AREA FRIDAY INTO FRIDAY NIGHT..WHILE THE GFS HAS RIDGING BUILDING IN. MAINTAINED SOME SMALL POPS AT THIS POINT. HOPING FOR SOME BETTER CONSISTENCY...OBVIOUSLY LOW CONFIDENCE OUT IN THE FRIDAY AND FRIDAY NIGHT TIME FRAME. SATURDAY SHOULD BE MAINLY DRY WITH THE NEXT SYSTEM MOVING IN FOR LATER IN THE WEEKEND. TIMING ISSUES CONTINUE WITH THE GFS BLASTING A COLD FRONT THROUGH QUICKER...BY SUNDAY MORNING. THE EURO HOLDS THE FRONT UP BY 12 HOURS OR SO. COLDER AIR IS PROGD TO FILTER IN BEHIND THIS SYSTEM...WITH THE EURO INDICATING -16 C AIR OVER LAKE MICHIGAN MONDAY AFTERNOON. GIVEN CONSISTENCY/TIMING ISSUES THE BULK OF THE LONG TERM...LOW CONFIDENCE OVERALL. MADE LITTLE IN THE WAY OF CHANGES AT THIS POINT. && .AVIATION...(1242 PM EST TUE DEC 27 2011) THE BACK EDGE OF THE STEADY SNOW EXTENDED FROM MOP TO AZO AS OF 1730Z. EAST OF THIS LINE IFR AND LIFR CONDITIONS PREVAIL. MEANWHILE TO THE WEST OF THIS LINE VSBYS GREATLY IMPROVE...HOWEVER CEILINGS REMAIN LARGELY IFR. THE SNOW SWATH AND LOWER VSBYS WILL CONTINUE TO END FROM WEST TO EAST...REACHING LAN AND JXN AROUND 00Z. SURFACE WINDS AND MIXING WILL GREATLY INCREASE EARLY THIS EVENING. THIS WILL HELP MOVE OUT ANY REMAINING IFR CEILINGS BY 03Z. VFR/MVFR CONDITIONS ARE EXPECTED OVERNIGHT...HOWEVER NW WINDS WILL OCCASIONALLY GUST AS HIGH AS 30 KNOTS. THESE WINDS WILL TAPER OFF TOWARD DAYBREAK ON WED. CONDITIONS FINALLY LOOK FAVORABLE FOR VFR FLYING WITH LIGHTER WINDS BY ABOUT 10Z WED AND SHOULD PREVAIL THROUGH 18Z WED. && .MARINE...(1115 AM EST TUE DEC 27 2011) WINDS WILL BEGIN RAMPING UP EARLY THIS AFTERNOON AND GUST TO GALE FORCE BY EARLY EVENING. GALE WARNING THROUGH THIS EVENING WITH GUST AROUND 35 KTS. && .HYDROLOGY...(450 AM EST TUE DEC 27 2011) NO SIGNIFICANT CHANGES TO RIVERS EXPECTED FOR THE NEXT SEVERAL DAYS. && .GRR WATCHES/WARNINGS/ADVISORIES... MI...NONE. LM...GALE WARNING ALL AREAS THROUGH TONIGHT. && $$ SYNOPSIS: 93 SHORT TERM: COBB LONG TERM: DUKE AVIATION: JK MARINE: COBB HYDROLOGY: 93
AREA FORECAST DISCUSSION
NWS GRAND RAPIDS MI
1115 AM EST TUE DEC 27 2011 LATEST UPDATE...MARINE AND SHORT TERM... .SYNOPSIS...(450 AM EST TUE DEC 27 2011) LOW PRESSURE MOVING NORTH FROM THE SOUTHERN US WILL COMBINE WITH COLDER AIR MOVING SOUTH FROM CANADA TO PRODUCE SOME LIGHT SNOW TODAY. LIGHT RAIN MAY MIX WITH THE SNOW...ESPECIALLY THIS MORNING. AN INCH OR TWO OF ACCUMULATION IS POSSIBLE WITH GREATEST AMOUNTS SOUTHEAST OF A KALAMAZOO TO LANSING LINE. WEDNESDAY WILL BE OUR COLDEST DAY WITH HIGHS AROUND 30. AFTER THAT HIGHS WILL CLIMB TO NEAR 40 THROUGH THE WEEKEND. A CLIPPER SYSTEM WILL BRING A CHANCE OF RAIN AND SNOW TO THE REGION THURSDAY. && .SHORT TERM...(1115 AM EST TUE DEC 27 2011) (TODAY THROUGH THURSDAY) * ACCUMULATING SNOW WILL TAPER TO FLURRIES/LIGHT RAIN EARLY THIS AFTERNOON WITH SNOW TOTALS OF 1 TO 3 INCHES...PRIMARILY GRASSY SURFACES...SIGNIFICANT WEATHER ADVISORY WAS ISSUED AT 10 AM. * GUSTY WINDS ALONG COAST THIS EVENING WILL BE LOOKING AT POSSIBLE WIND ADVISORY FOR THE COAST... RADAR INDICATING TWO BANDS OF MODERATE SNOW AT THE PRESENT TIME. BOTH ARE ORIENTED SSW-NNE WITH ONE FROM KGRR TO KMOP...WITH THE SECOND BAND ALONG A KOEB...KJXN...KFNT LINE. BOTH BANDS ARE SLOWLY MOVING EAST AND ARE EXPECTED TO WEAKEN AS THE MIDLEVEL FRONTOGENSIS SHIFT TO THE NORTHEAST AND SURFACE COLD FRONT SWEEPS EASTWARD THIS AFTERNOON. THE HRRR RUC HAS HAD A REALLY GOOD HANDLE ON THE EVOLUTION OF THE SYSTEM THIS MORNING AND HAVE LEVERAGED IT HEAVILY IN UPDATING SNOWFALL GRIDS. ALTHOUGH...HALF OF THE SNOW HAS FALLEN...LOOKS LIKE LOCAL TOTALS OF 3 INCHES ARE LIKELY. TEMPERATURES ARE EXPECTED TO RISE INTO THE MID 30S THIS AFTERNOON AS THE SNOW TAPERS OFF AND MAY EVEN END AS A MIX WITH RAIN BEFORE ENDING. THIS EVENING WINDS WILL KICK UP AS COLDER AIR FLOWS IN BEHIND THE LOW AS IT MOVES BY TO THE SOUTHEAST. STRONGEST WINDS WILL BE NEAR THE LAKE SHORE. PCPN WILL DIMINISH THIS EVENING. THERE MAY BE A FEW SNOW SHOWERS ALONG THE LAKE SHORE IN NORTH FLOW AS H8 TEMPS FALL BRIEFLY TO AROUND -12C. MOISTURE IS SHALLOW THOUGH AND NOTHING ORGANIZED IS EXPECTED. THE NEXT CLIPPER WILL MOVE TOWARD THE REGION WEDNESDAY NIGHT AND THURSDAY. AS HAS BEEN TYPICAL LATELY...THIS SYSTEM WILL SCOOT BY TO THE NORTH. THAT MEANS WE/LL SEE SOME WARMER AIR FLOW INTO THE CWA AND MIXED RAIN/SNOW IS EXPECTED IN THE SRN CWA WITH MORE SNOW IN THE NORTH. APPRECIABLE ACCUMS ARE NOT EXPECTED. && .LONG TERM...(450 AM EST TUE DEC 27 2011) (THURSDAY NIGHT THROUGH MONDAY) ZONAL FLOW IS FORECAST TO CONTINUE OVER THE LOWER 48 FOR MUCH OF THE LONG TERM...TRANSITIONING TO AN EASTERN TROUGH/WESTERN RIDGE TOWARD THE END OF THE PERIOD. GENERALLY LIGHT PRECIPITATION IS EXPECTED THROUGH THE PERIOD. TIMING ISSUES ARE ALWAYS A CONCERN IN ZONAL FLOW AND THIS FORECAST IS NO EXCEPTION. FIRST WEAK SHORTWAVE TO DEAL WITH IS MOVING THROUGH THE GREAT LAKES THURSDAY NIGHT. LOOKS LIKE MAINLY LIGHT SNOW...WITH QPF TOTALS THAT ARE ON THE ORDER OF 0.10 OR LESS...SO NO ISSUES EXPECTED. THE EUROPEAN HAS ANOTHER WAVE AFFECTING THE AREA FRIDAY INTO FRIDAY NIGHT..WHILE THE GFS HAS RIDGING BUILDING IN. MAINTAINED SOME SMALL POPS AT THIS POINT. HOPING FOR SOME BETTER CONSISTENCY...OBVIOUSLY LOW CONFIDENCE OUT IN THE FRIDAY AND FRIDAY NIGHT TIME FRAME. SATURDAY SHOULD BE MAINLY DRY WITH THE NEXT SYSTEM MOVING IN FOR LATER IN THE WEEKEND. TIMING ISSUES CONTINUE WITH THE GFS BLASTING A COLD FRONT THROUGH QUICKER...BY SUNDAY MORNING. THE EURO HOLDS THE FRONT UP BY 12 HOURS OR SO. COLDER AIR IS PROGD TO FILTER IN BEHIND THIS SYSTEM...WITH THE EURO INDICATING -16 C AIR OVER LAKE MICHIGAN MONDAY AFTERNOON. GIVEN CONSISTENCY/TIMING ISSUES THE BULK OF THE LONG TERM...LOW CONFIDENCE OVERALL. MADE LITTLE IN THE WAY OF CHANGES AT THIS POINT. && .AVIATION...(715 AM EST TUE DEC 27 2011) PRECIPITATION HAS OVERSPREAD ALL OF THE TAF SITES THIS MORNING...WITH A MIXTURE OF RAIN AND SNOW ACROSS THE AREA. THE TREND SHOULD BE TO ALL SNOW BY MID MORNING. CEILINGS ARE TRENDING DOWN AND THAT SHOULD CONTINUE TO BE THE CASE THROUGH THE MORNING HOURS. BY LATE MORNING...CONDITIONS WILL BE POOR RANGING FROM IFR TO LIFR. AN IMPROVEMENT WILL OCCUR SLOWLY THIS AFTERNOON FROM WEST TO EAST AS THE SYSTEM RESPONSIBLE FOR THE SNOW PULLS AWAY TO THE EAST. MVFR CONDITIONS ARE EXPECTED BY MID TO LATE AFTERNOON. CONDITIONS WILL IMPROVE TO VFR TONIGHT...WITH SOME VFR CEILINGS EXPECTED OFF OF LAKE MICHIGAN. IT WILL BECOME WINDY THIS AFTERNOON...ESPECIALLY AT KMKG WITH A NORTHWEST WIND OFF THE LAKE. GUSTS WILL RANGE FROM 20 TO 30 KNOTS AT MOST LOCATIONS THIS AFTERNOON AND EVENING FROM THE NORTHWEST. && .MARINE...(1115 AM EST TUE DEC 27 2011) WINDS WILL BEGIN RAMPING UP EARLY THIS AFTERNOON AND GUST TO GALE FORCE BY EARLY EVENING. GALE WARNING THROUGH THIS EVENING WITH GUST AROUND 35 KTS. && .HYDROLOGY...(450 AM EST TUE DEC 27 2011) NO SIGNIFICANT CHANGES TO RIVERS EXPECTED FOR THE NEXT SEVERAL DAYS. && .GRR WATCHES/WARNINGS/ADVISORIES... MI...NONE. LM...GALE WARNING ALL AREAS THROUGH TONIGHT. && $$ SYNOPSIS: 93 SHORT TERM: COBB LONG TERM: DUKE AVIATION: DUKE MARINE: COBB HYDROLOGY: 93
AREA FORECAST DISCUSSION
NWS GRAND FORKS ND
1033 AM CST TUE DEC 27 2011 .DISCUSSION... MORNING UPDATE CONCENTRATES ON SKY AND TEMPS. EARLY VIS SHOWED STRATOCU DECK EAST OF THE VALLEY...HOWEVER IT IS QUICKLY BREAKING UP AS EVIDENT FROM WEB CAMS OVER THE BJI AREA. THUS BUMPED UP SKY FROM 15Z TO 21Z AND THEN BEGAN TO SCATTER IT BACK OUT. LIKELY SCENARIO IS THAT CIRRUS WILL ARRIVE BEFORE SCATTERING COMPLETELY OUT. LATEST NAM ISENTROPIC CHARTS AND LOW LEVEL WARM ADVECTION STARTING TO KICK IN AROUND 21Z...THUS NOT SURE WE WILL SEE ANY SNOW OUT WEST IN THE 18Z TO 21Z TIMEFRAME...BUT BY 00Z IT IS A POSSIBILITY. CURRENT POP GRIDS LOOK DECENT ALTHOUGH MAY PULL 18Z TO 21Z POPS AFTER FURTHER ANALYSIS. TEMPS CURRENTLY COLDER THAN PREV FCST ADVERTISED...BUT WITH WARM ADVECTION KICKING IN MID AFTN THINK FCST HIGHS ARE REASONABLE DESPITE CIRRUS. MADE ADJUSTMENTS TO HOURLY TEMPS TO COMPENSATE FOR CURRENT OBS AND A LATER START. && .AVIATION... LOW CLOUDS WITH MVFR/LCLLY IFR/ PTCHY 4SM -SN CONTINUE OVER PORTIONS OF NORTHWEST MINNESOTA. CLOUD DECK APPEARS THIN AND IS MOVING DUE SOUTH AROUND 10 KTS. RUC13 MODEL X-SECT AND SAT/11-3.9/ SUGGEST SHOULD CLEAR TVF AROUND 18Z BUT HOLD IN BJI AREA THROUGH 00Z. WINDS WILL CONTINUE TO DECREASE AND BECOME VRB AROUND 00Z TVF/BJI WITH SFC RIDGE OVER AREA. VFR ALONG AND WEST OF RRV THROUGH 00Z. A BAND OF LIGHT SNOW WITH MVFR CEILINGS IS EXPECTED OVERNIGHT...BUT ADJUSTMENTS IN TIMING ARE LIKELY THROUGH THE DAY. && .PREV DISCUSSION... /ISSUED 356 AM CST TUE DEC 27 2011/ SHORT TERM...TODAY THROUGH THURSDAY NIGHT PRIMARY FORECAST CHALLENGE WILL BE PRECIPITATION CHANCES AND AMOUNTS TONIGHT THROUGH MUCH OF THE WEEK AS A SERIES OF WAVES MOVE ACROSS THE NORTHERN PLAINS IN FAST NORTHWEST FLOW ALOFT. GFS/ECMWF/GEM IN REASONABLE AGREEMENT THROUGH THURSDAY MORNING...DIVERGING SOMEWHAT THEREAFTER. THE NAM IS A BIT OF AN OUTLIER AND WILL NOT BE USED IN THIS FORECAST PACKAGE. COLD FRONT FROM LAST EVENING HAS MOVED WELL SOUTH OF THE FORECAST AREA WITH STRONG COLD AIR ADVECTION AND BREEZY NORTHERLY WINDS IN ITS WAKE. SURFACE TEMPERATURES ACROSS SOUTHERN MANITOBA ARE IN THE LOW SINGLE DIGITS ABOVE ZERO AND THIS COLD AIR WILL CONTINUE TO FILTER TO THE SOUTH THROUGH THE EARLY MORNING HOURS. LOW STRATUS ALONG AND SOUTHEAST OF A LINE FROM JAMESTOWN TO GRAND FORKS TO ROSEAU WILL CONTINUE TO SLIDE SOUTH AND EAST...RESULTING IN MOSTLY SUNNY SKIES BY MID TO LATE MORNING REGION WIDE. NORTH WINDS WILL RELAX THROUGH THE DAY AS THE PRESSURE GRADIENT WEAKENS AND SURFACE HIGH PRESSURE MOVES INTO THE NORTHERN PLAINS. WITH A DRAMATIC CHANGE IN THE AIR MASS...TEMPERATURES TODAY WILL BE 20 TO 30 DEGREES LOWER THAN YESTERDAY/S RECORD HIGHS. FOR TONIGHT...A NARROW BAND OF LIGHT SNOW WILL MOVE FROM WEST TO EAST ACROSS THE FORECAST AREA...COINCIDENT WITH INCREASING MID- LEVEL WARM AIR ADVECTION/CLOUD COVER AND MODEST ISENTROPIC LIFT ON THE 280 K SURFACE. ACCUMULATIONS WILL BE LIGHT...BUT SOME SPOTS MAY RECEIVE UP TO AN INCH OF NEW SNOW BY WEDNESDAY MORNING. ANOTHER WAVE WILL MOVE THROUGH THE REGION WEDNESDAY AND WEDNESDAY NIGHT...BRINGING A BETTER CHANCE OF ACCUMULATING SNOW (1-2 INCHES) ACROSS PORTIONS OF EASTERN ND AND NORTHWEST MN. THE ECMWF AND GEM SURFACE LOW TRACKS ARE A BIT FARTHER SOUTH THAN THE GFS...BUT ALL THREE MODELS SHOW A BAND OF ROUGHLY ONE TENTH OF AN INCH LIQUID QPF BISECTING THE FORECAST AREA FROM NORTHWEST TO SOUTHEAST. ECMWF RUN TO RUN CONSISTENCY IS SLIGHTLY BETTER THAN THE GFS...SO PREFER ITS MORE SOUTHERN SOLUTION...WHICH PLACES THE MOST PRECIPITATION ALONG A RUGBY TO VALLEY CITY TO WAHPETON LINE. DUE TO DIFFERENCES IN TRACK...WILL KEEP POPS IN THE CHANCE CATEGORY FOR NOW. TEMPERATURES WEDNESDAY WILL ONCE AGAIN CLIMB TO WELL ABOVE NORMAL WITH HIGHS APPROACHING 40 DEGREES IN THE SOUTHERN VALLEY...SO INITIAL PRECIPITATION PHASE MAY BE A RAIN/SNOW MIX OR ALL RAIN. MODELS ARE IN POOR AGREEMENT THURSDAY AND THURSDAY NIGHT WITH THE GFS DRY AND THE ECMWF/GEM/NAM BRINGING ANOTHER BAND OF LIGHT SNOW ACROSS THE REGION LATE IN THE DAY. WILL KEEP CHANCE POPS GOING...BUT ADJUSTMENTS WILL BE NEEDED ONCE MODELS COME INTO BETTER AGREEMENT. TEMPERATURES WILL DROP SOME ON THURSDAY...BUT STILL REMAIN ABOVE LATE-DECEMBER NORMALS WITH HIGHS IN THE MID 20S TO MID 30S. LONG TERM...FRIDAY THROUGH MONDAY NIGHT WILL CONTINUE TO KEEP THE 20-30 POPS WE HAVE GOING FOR FRIDAY... AS ALL DETERMINISTIC MODELS ARE IN PRETTY GOOD AGREEMENT ON BREAKING OUT SOME PRECIP AS A WEAK SHORTWAVE MOVES THROUGH THE AREA. A MORE SIGNIFICANT WAVE APPROACHES THE AREA ON SATURDAY... AND THERE IS SOME VARIATION ON HOW FAST THE MODELS BRING THE SYSTEM THROUGH. THE ECMWF CLOSES OFF A LOW AND IS MUCH SLOWER THAN THE GFS AND GEM...WHICH BRING A COLD FRONT THROUGH FAIRLY EARLY ON THE DAY ON SATURDAY. THE ECMWF CONTINUES WITH WARM AIR ADVECTION IN SATURDAY AFTERNOON. ENSEMBLE SPREAD IS PRETTY HIGH WITH THE SYSTEM...BUT THE GFS ENSEMBLE MEAN HAS SOME WARMER TEMPS IN THE SOUTHERN CWA LIKE THE OPERATIONAL ECMWF. BUMPED UP TEMPS A BIT IN THE SOUTHERN COUNTIES...AND INCLUDED A MIX OF RAIN AND SNOW MENTION. MODEL CONSENSUS GOES FURTHER DOWNHILL ON DAYS 6 AND 7...WITH THE GFS AND GEM SETTING UP NEAR ZONAL FLOW AND THE ECMWF BECOMING VERY MERIDIONAL AS THE UPPER TROUGH DIGS INTO THE GREAT LAKES. WENT WITH THE COMPROMISE ALLBLEND AND WILL CONTINUE TO KEEP SOME LOW POPS IN THE NORTH AND EAST FOR SUNDAY IN CASE THE SLOWER ECMWF VERIFIES...BUT KEPT TEMPS WARMER THAN THE NORTHERLY FLOW OF THE ECMWF WOULD INDICATE. && .FGF WATCHES/WARNINGS/ADVISORIES... ND...NONE. MN...NONE. && $$ SPEICHER/EWENS
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
1132 AM CST TUE DEC 27 2011 .SHORT TERM...TODAY THROUGH THURSDAY NIGHT 305 AM CST TUE DEC 27 2011 MAIN FORECAST CONCERN IS ON LOW PRECIPITATION CHANCES THROUGHOUT THE SHORT TERM PERIOD. CURRENTLY AS OF 08Z...WATER VAPOR LOOP AND RUC 500MB HEIGHT ANALYSIS SHOWED A SHORTWAVE TROUGH OVER BRITISH COLUMBIA...WEAK RIDGING OVER THE SOUTHWEST U.S. INTO ALBERTA AND SASKATCHEWAN...AN UPPER TROUGH OVER MINNESOTA AND AN UPPER LOW OVER NORTHERN MISSISSIPPI. THE UPPER TROUGH IS GRADUALLY BRINGING COLDER AIR INTO THE UPPER MISSISSIPPI RIVER VALLEY REGION...NOTED BY 850MB TEMPS THAT FELL BETWEEN 12Z YESTERDAY AND 00Z TODAY FROM 4C TO 1C AT MPX...AND 6 TO -2C AT BIS. MORE COLD AIR LURKS FARTHER UPSTREAM WITH -12C REPORTED AT THE PAS MANITOBA. MID TO UPPER LEVEL DYNAMIC LIFT WITH THE TROUGH IS FAIRLY WEAK AND MOSTLY OFF TO THE EAST OVER LAKE MICHIGAN...PER QG APPEARANCE FROM THE RUC/ECMWF. THIS LIFT IS WHAT HELPED PRODUCE THE RAIN/SLEET/SNOW LAST EVENING. BIGGER ISSUE WITH THE UPPER TROUGH IS ACTUALLY THE SUBSIDENCE AND THE COLD ADVECTION...WHICH IS HELPING TO PRODUCE 15-20 KT SURFACE SUSTAINED WINDS AND GUSTS TO 30 KT ACROSS MUCH OF MINNESOTA. THESE ARE OCCURRING IN THE WAKE OF TWO COLD FRONTS: THE FIRST SITUATED NORTH-SOUTH OVER CENTRAL WISCONSIN AND THE SECOND ALIGNED WEST EAST FROM ABERDEEN SOUTH DAKOTA INTO UPPER MICHIGAN. A LARGE AMOUNT OF STRATUS EXISTS BEHIND THESE FRONTS...WITH THE LOWEST CEILINGS BEHIND THE SECONDARY FRONT WHERE A GREATER SURGE OF COLD AIR ADVECTION IS HELPING TO UNDERCUT LOW LEVEL MOISTURE. A FEW FLURRIES ALSO OCCURRING FROM THE STRATUS. TODAY AND TONIGHT...MODELS PROG THE UPPER TROUGH OVER MINNESOTA TO MOVE RAPIDLY TO THE EAST...IN RESPONSE TO FAST FLOW COMING OFF THE PACIFIC. BY MIDNIGHT TONIGHT...THE UPSTREAM WEAK RIDGING SHOULD HAVE MOVED INTO THE FORECAST AREA. THIS SITUATION MEANS THAT THE CURRENT STRATUS AND STRONGER WINDS MOVING INTO THE FORECAST AREA FROM MINNESOTA WILL NOT STAY AROUND LONG. IN FACT...GOOD MODEL AGREEMENT EXISTS THAT SKIES SHOULD CLEAR OUT ACROSS MINNESOTA AND IOWA BETWEEN 18-21Z TODAY. ON THE OTHER HAND...OVER WISCONSIN...THERE ARE SUGGESTIONS BY THE 27.00Z NAM/27.03Z RUC THAT THE STRATUS MAY LINGER THROUGH THE EVENING BEFORE DISSIPATING AFTER MIDNIGHT (PER 925MB RH DATA). THIS CERTAINLY SEEMS PLAUSIBLE...SINCE STRATUS TYPICALLY LINGERS LONGER THAN ONE WOULD EXPECT THIS TIME OF YEAR. ALSO...THERE SHOULD BE A GOOD TRANSPORT OF MOISTURE OFF LAKE SUPERIOR GIVEN COLDER AIR FLOWING SOUTH. THEREFORE...HAVE RAISED SKY COVER VALUES OVER WISCONSIN FOR THIS EVENING. REGARDING PRECIP CHANCES WITH THE STRATUS...ANY LIFT IS VERY WEAK...ASSOCIATED WITH LOW LEVEL FRONTOGENESIS. GIVEN OVERALL LACK OF PRECIPITATION RIGHT NOW ON RADAR...ONLY WENT WITH FLURRIES THIS MORNING. DRYING TREND SHOWING UP NOW IN THE HRRR RUNS WOULD AGREE WITH THIS AS WELL. AFTER THAT... SUBSIDENCE TAKING HOLD SHOULD SHUT OFF ANY PRECIPITATION ACTION. LOOKING AHEAD TO AFTER MIDNIGHT TONIGHT...SHORTWAVE TROUGH OVER BRITISH COLUMBIA ALONG WITH A WEAKER SHORTWAVE CURRENTLY SEEN OVER IDAHO ARE FORECAST TO BEGIN TO DROP DOWN INTO MINNESOTA AROUND 12Z TUESDAY. WARM ADVECTION AHEAD OF THESE SHOULD RESULT IN A MID CLOUD DECK OF STRATUS...WHILE ANY PRECIPITATION STAYS NORTHWEST OF THE FORECAST AREA. REGARDING TEMPERATURES...WITH COLD ADVECTION OCCURRING TODAY NOTED BY 850MB TEMPS FALLING TO -5 TO -8C BY 18Z...ANTICIPATING GENERALLY STEADY OR FALLING TEMPERATURES. TONIGHT IS A LITTLE TRICKY WITH STRATUS OVER WISCONSIN AND THEN CLOUDS COMING IN AFTER MIDNIGHT EVERYWHERE. FOR NOW HAVE FOLLOWED A BLEND OF GUIDANCE FOR LOWS. WEDNESDAY AND WEDNESDAY NIGHT...SHORTWAVE OVER MINNESOTA AT 12Z WEDNESDAY IS FORECAST TO SHIFT EAST FAIRLY QUICKLY...REACHING LOWER MICHIGAN BY 00Z THURSDAY. BIGGEST CONCERN WITH THIS SHORTWAVE IS POTENTIAL FOR SOME WARM ADVECTION LIGHT SNOW SKIRTING TAYLOR AND CLARK COUNTIES. THE 00Z NAM/26.21Z SREF SUGGEST THIS IS POSSIBLE... WHEREAS THE 27.00Z GFS/26.12Z ECMWF ARE DRY. GIVEN THE WAY RECENT SYSTEMS HAVE GONE...WITH LIGHT PRECIPITATION HAPPENING DESPITE PRESENCE OF LOW LEVEL DRY AIR...FEEL COMPELLED TO AT LEAST PLACE A 20 PERCENT CHANCE IN TAYLOR AND CLARK COUNTIES. ELSEWHERE...A DECREASING CLOUD TREND SHOULD OCCUR WITH TEMPERATURES CLIMBING INTO THE 30S. COULD SEE READINGS PUSH 40 IN FAR WESTERN AREAS. FOR WEDNESDAY NIGHT...ATTENTION RE-FOCUSES TO THE NORTHWEST WHERE MODELS SHOW A DECENT SHORTWAVE MOVING THROUGH A FAST WEST-NORTHWEST UPPER LEVEL FLOW. AT 00Z...MODELS SUGGEST IT IS EITHER OVER EASTERN MONTANA OR SOUTHEAST SASKATCHEWAN...THEN IT MARCHES SOUTHEAST INTO THE FORECAST AREA AROUND 12Z THURSDAY. AS FAR AS WHERE IN THE FORECAST AREA...THIS VARIES GREATLY...SO FOR NOW HAVE TAKEN A BLEND APPROACH GIVEN THE FAST FLOW. AS THE SHORTWAVE APPROACHES...SHOULD SEE MID AND HIGH CLOUDS DEVELOP IN RESPONSE TO WARM ADVECTION AND DPVA FORCING. LIGHT PRECIPITATION COULD EVEN START BREAKING OUT IN NORTHWESTERN PORTIONS OF THE AREA IN THE EVENING. AFTER MIDNIGHT... ANTICIPATING SOME LIGHT PRECIPITATION EVERYWHERE. PRECIPITATION CHANCES REMAIN IN THE 20 TO 30 RANGE...HOWEVER...DUE TO THE LARGE SPREAD IN TRACK OF THE SHORTWAVE. ENVISION CHANCES NEEDING A BUMP UP IN LATER FORECASTS...BUT WHERE IS THE QUESTION. WITH THE CLOUDS MOVING IN...NOT ANTICIPATING AS MUCH OF A TEMPERATURE FALL AS TONIGHT. GENERALLY FOLLOWED A BLEND OF GUIDANCE FOR LOWS. THURSDAY AND THURSDAY NIGHT...SIMILAR TO THE PAST FEW DAYS...THE PARADE OF SHORTWAVES FROM THE PACIFIC CONTINUE TO COME THROUGH THE FAST FLOW. SHORTWAVE THAT IS NEAR/OVER THE AREA AT 12Z THURSDAY IS PROGGED TO REACH LOWER MICHIGAN BY 00Z...WHILE ANOTHER SHORTWAVE MOVES INTO THE DAKOTAS. SHOULD SEE THE PRECIPITATION DIMINISH FOR A TIME THURSDAY...ESPECIALLY IN THE AFTERNOON NORTH OF I-90 AS THAT AREA GETS INTO THE SUBSIDENCE BEHIND THE MORNING SHORTWAVE. DURING THE AFTERNOON...PRECIPITATION IS POSSIBLE SOUTH OF I-90 AS WARM ADVECTION OCCURS DOWNSTREAM OF THE SHORTWAVE ENTERING THE DAKOTAS. WITH UNCERTAINTY ON THE PLACEMENT OF THE SHORTWAVE NEAR/OVER THE AREA AT 12Z THURSDAY...ALONG WITH SUGGESTIONS OF LOW LEVEL DRY AIR TO OVERCOME IN SOUNDINGS...HAVE KEPT PRECIPITATION CHANCES BETWEEN 20 AND 30. A LOT OF UNCERTAINTY EXISTS WITH THIS DAKOTAS SHORTWAVE HEADING INTO THURSDAY NIGHT...WHERE THE 27.00Z ECMWF/UKMET DROP IT DOWN INTO MISSOURI WHEREAS THE 27.00Z GFS CROSSES IOWA AND THE 27.00Z NAM CROSSES THE FORECAST AREA. FEELING IS THE SOUTHERN SOLUTIONS MAY HAVE A BETTER CHANCE OF VERIFYING...DUE TO THE USUAL BETTER PREDICTABILITY OF THE ECMWF...BUT NOT COMPLETELY SURE GIVEN THE FAST FLOW. THEREFORE...20 TO 30 PERCENT CHANCES CONTINUE FOR THURSDAY NIGHT. WITH SO MUCH UNCERTAINTY ON THE TRACKS OF THESE SHORTWAVES...TEMPERATURE FORECASTS ARE PROBLEMATIC. CERTAINLY POTENTIAL EXISTS ON THURSDAY FOR AT LEAST THE SOUTHERN PORTION OF THE AREA TO HIT 40 OR HIGHER...ESPECIALLY IF THE SHORTWAVE THEN TRACKS FARTHER NORTH. CLOUDS THURSDAY NIGHT SHOULD HOLD TEMPERATURES UP IN THE 20S TO LOW 30S...COLDEST IN TAYLOR AND CLARK COUNTIES WHERE COOLER AIR SINKS SOUTH BEHIND THE SHORTWAVE MOSTLY SUGGESTED TO TRACK NEAR OR SOUTH OF THE AREA. .LONG TERM...FRIDAY THROUGH MONDAY NIGHT 305 AM CST TUE DEC 27 2011 27.00Z MODEL CYCLE CONSISTING OF THE ECMWF/GFS/CANADIAN AND GFS ENSEMBLES STILL PRESENT PLENTY OF UNCERTAINTY WITH REGARDS TO THE UPPER LEVEL PATTERN THROUGHOUT THE LONG TERM PERIOD...THOUGH THERE ARE SOME FEATURES THAT CAN BE LATCHED ONTO. THE FIRST IS A FAIRLY POTENT SHORTWAVE TROUGH POISED TO COME INTO THE PACIFIC NORTHWEST ON FRIDAY...RESULTING IN BUILDING RIDGING DOWNSTREAM TOWARDS THE FORECAST AREA. THIS RIDGING LOOKS TO BUILD INTO THE AREA FRIDAY NIGHT...BRINGING IN A SURGE OF DOWNSLOPED PACIFIC AIR. TIMING THE PACIFIC NORTHWEST SHORTWAVE TROUGH AND INTENSITY WILL BE CRITICAL IN DETERMINING HOW WARM NEW YEARS EVE IS. LOOKS LIKE THERE SHOULD BE SOME WARM ADVECTION PRECIPITATION DOWNSTREAM INTO THE AREA FRIDAY/FRIDAY NIGHT...BUT THIS MOSTLY LIFTS NORTH ON NEW YEARS EVE. THE 26.12Z/27.00Z ECMWF RUNS ARE BY FAR THE MOST AMPLIFIED... RESULTING IN A SLOWER COLD FRONTAL PASSAGE AND HIGH TEMPERATURES SATURDAY FROM THE 40S INTO THE LOW 50S. FOR NOW HAVE TAKEN A 30 DAY BIAS CORRECTION OF THE CONSENSUS OF ALL GUIDANCE...WHICH RESULTS IN HIGHS MOSTLY IN THE 40S. CERTAINLY POTENTIAL EXISTS FOR WARMER READINGS GIVEN LACK OF SNOW COVER STILL ANTICIPATED. COLDER AIR WILL MOVE INTO THE AREA FOR NEW YEARS DAY AS THE UPPER TROUGH MOVES IN...BUT HOW MUCH DEPENDS ON THE PROGRESSIVE NATURE OF THE UPPER TROUGH. THE MORE AMPLIFIED ECMWF BASICALLY TURNS THE TROUGH INTO A LONGWAVE TROUGH...ALLOWING FOR AIR OF MORE ARCTIC ORIGIN TO FLOW SOUTH INTO THE AREA FOR NEW YEARS DAY AND MONDAY. ON THE OTHER HAND...THE 27.00Z GFS/CANADIAN DEPICT MUCH MORE PROGRESSION... RESULTING IN A CONTINUED FEED OF PACIFIC AIR AND WARMER. GIVEN SO MUCH UNCERTAINTY...A CONSENSUS OF GUIDANCE WAS FOLLOWED FOR NEW YEARS DAY THROUGH MONDAY NIGHT. IN EITHER MODEL CAMP SCENARIO...IT LOOKS LIKE LITTLE IF ANY PRECIPITATION WILL OCCUR. && .AVIATION...THROUGH 18Z WEDNESDAY 1131 AM CST TUE DEC 27 2011 WINDS WILL GRADUALLY DIMINISH THIS AFTERNOON AS HIGH PRESSURE BUILDS INTO THE REGION. LOOK FOR NORTHEAST WINDS AT 15 TO 20 KTS GUSTING TO AROUND 27 KTS EARLY THIS AFTERNOON...THEN DECREASING INTO THE 10 TO 13 KT RANGE AS THE HIGH EDGES INTO THE AREA. MVFR CEILINGS WILL IMPROVE TO VFR THIS AFTERNOON...WITH A FEW LINGERING CUMULUS IN THE AREA...WITH CLOUD BASES AROUND 2 KFT. A SHORTWAVE TROUGH IS EXPECTED TO MOVE ACROSS THE DAKOTAS AND INTO THE AREA TONIGHT...SPREADING MID LEVEL CLOUDS ACROSS THE AREA. LOOK FOR CLOUD BASES IN THE 5 TO 8 KFT RANGE AS THE TROUGH MOVES THROUGH. VFR CONDITIONS WILL PERSIST OVERNIGHT INTO WEDNESDAY MORNING. LIGHT AND VARIABLE WINDS OVERNIGHT WILL BECOME SOUTH LATE WEDNESDAY MORNING IN THE 10 TO 15 KT RANGE. && .ARX WATCHES/WARNINGS/ADVISORIES... 305 AM CST TUE DEC 27 2011 WI...NONE. MN...NONE. IA...NONE. && $$ SHORT TERM...AJ LONG TERM...AJ AVIATION...WETENKAMP