FXUS62 KRAH 080840 AFDRAH AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE RALEIGH NC 340 AM EST SUN NOV 8 2009 .SYNOPSIS... HIGH PRESSURE WILL REMAIN ACROSS THE CAROLINAS THROUGH MONDAY. A TROUGH OF LOW PRESSURE WILL APPROACH FROM THE WEST TUESDAY. THIS IS EXPECTED TO PULL SOME OF THE DEEP MOISTURE ASSOCIATED WITH TROPICAL STORM IDA ACROSS THE REGION TUESDAY INTO EARLY WEDNESDAY. && .NEAR TERM /THROUGH MONDAY/... AS OF 215 AM SUNDAY... A FAIRLY STRAIGHTFORWARD MAINLY TEMPERATURE FORECAST THROUGH MONDAY... AS A MID LEVEL RIDGE EXPANDS NORTHEASTWARD ACROSS THE CAROLINAS AND PROMOTES CONTINUED MODIFICATION OF THE SURFACE RIDGE BENEATH. CLEAR SKIES THROUGH TONIGHT SHOULD BECOME CIRRUS-FILLED PARTLY CLOUDY BY MONDAY AFTERNOON... AS HIGH LEVEL MOISTURE STREAMS NORTHEASTWARD FROM THE GULF OF MEXICO. PROJECTED LOW LEVEL THICKNESSES GENERALLY IN THE 1370S METERS SUPPORT HIGH TEMPERATURES BOTH DAYS IN THE LOWER TO MIDDLE 70S. ASIDE FROM SOME LIGHT NORTHEASTERLY STIRRING... MAINLY OVER SOUTHERN NC (AWAY FROM THE SURFACE RIDGE AXIS EXPECTED TO LIE ALONG THE VA/NC BORDER)... RADIATIONAL COOLING SHOULD AGAIN BE GOOD AND SUPPORT LOWS TONIGHT IN THE UPPER 30S TO MIDDLE 40S. && .SHORT TERM /MONDAY NIGHT THROUGH TUESDAY NIGHT/... AS OF 340 AM SUNDAY... THOUGH CONFIDENCE IN THIS PORTION OF THE FORECAST REMAINS LOW... THERE IS A GROWING CONSENSUS AMONGST THE MAJORITY OF THE MEDIUM RANGE MODELS -- NAMELY THE 00Z/8TH GEM/GFS/ECMWF -- WHICH SUPPORT AN INCREASINGLY WET PERIOD BY TUESDAY NIGHT. THE SOUTHERN OUTLIER (WRT NORTHEASTWARD ADVANCEMENT OF PRECIP) NAM INITIALIZED THE POSITION AND STRENGTH OF IDA MOST POORLY OF ALL GUIDANCE... AND HAS BEEN DISCOUNTED. THE LOW CONFIDENCE FORECAST HINGES UPON THE INTERACTION OF MULTIPLE FEATURES... INCLUDING 1) IDA... 2) A WESTERN GULF OF MEXICO LOW LEVEL PV MAX... 3) A SOUTHERN STREAM UPPER TROUGH NEARING THE RIO GRANDE... AND 4) A PARADE OF FAST NORTHERN STREAM ENERGY STRETCHING FROM IDAHO WEST NORTHWESTWARD TOWARD THE GULF OF ALASKA. DESPITE INEVITABLE TIMING AND LOCATION DIFFERENCES WRT THE EVOLUTION OF THOSE FEATURES... A DOMINANT SIGNAL OF STRONG JET ENTRANCE REGION FORCING FOR ASCENT -- FIRST FROM THE SOUTHERN STREAM TROUGH AND COMBINED DIABATIC MESOSCALE OUTFLOW JET COMPONENT FROM THE SOUTH... AND THEN FROM A PHASING OF THIS JET WITH THE NORTHERN STREAM PJ -- WITHIN A DEEP 1.5 TO 2.0 INCH PWAT TROPICAL MOISTURE PLUME BY TUESDAY EVENING. THIS PATTERN SUGGESTS MOST OF CENTRAL NC WILL SEE MEASURABLE RAIN (PERHAPS A GOOD SOAKING RAIN OF *AT LEAST ONE QUARTER TO ONE HALF INCH) BY TUESDAY NIGHT... AND HAVE ACCORDINGLY INCREASED POP TO LIKELY AT THAT TIME. PRECIPITATION AMOUNTS REMAIN IN QUESTION... HOWEVER... SINCE THE PATTERN IS ALSO SUPPORTIVE OF DIABATIC-INDUCED LOW LEVEL PV ANOMALIES (FROM CONVECTIVE FEEDBACK) AND ENHANCED MOIST SOUTHEASTERLY LOW LEVEL FLOW ALONG THE INVERTED H85 TROUGH WELL TO THE NORTHEAST OF THE CENTER OF IDA... WHICH THE GEM AND GFS SIMULATE (THOUGH PROBABLY TO THE EXTREME). INDEED... IT APPEARS THAT THE PV TOWER (CIRCULATION) ASSOCIATED WITH IDA MAY NEVER MAKE IT TO OUR LATITUDE. INSTEAD -- AS MID LEVEL RIDGING REASSERTS ITSELF IN THE WAKE OF THE NORTHERN STREAM TROUGH -- THIS PV TOWER MAY STALL NEAR THE GULF COAST AND MAKE A CLOCKWISE LOOP TO THE SOUTH AND THEN NORTHWEST IN THE GULF OF MEXICO... ONLY TO GET ENTRAINED NORTHWARD AHEAD OF THE NEXT UPSTREAM TROUGH AND MAKE ANOTHER RUN TOWARD THE WEST CENTRAL GULF COAST STATES IN A STRUNG-OUT WEAKENED STATE BY THIS WEEKEND? THE NWP MODELS ALSO THEN DEPICT A CLASSIC CASE OF POSITIVE FEEDBACK SUTCLIFFE-PETTERSSEN SELF DEVELOPMENT (CONSISTENT WITH MUTUAL UPPER/LOWER WAVE AMPLIFICATION FROM PV THINKING) TUESDAY NIGHT THROUGH THE MIDDLE PART OF THE WEEK ALONG THE SOUTHEAST AND MID ATLANTIC COASTS... WHEREBY THE INITIALLY SEPARATE NORTHERN STREAM UPPER TROUGH AND AFOREMENTIONED LOW LEVEL PV ANOMALY BECOME "PHASE-LOCKED"/OCCLUDED INTO A VERY POWERFUL WESTERN ATLANTIC GALE. SUCH DEVELOPMENT IS ONLY LIKELY TO OCCUR PROVIDED A SURFACE WAVE (LOW LEVEL PV ANOMALY) INDEED EMERGES NORTHEASTWARD AHEAD OF IDA. OTHERWISE... THE NORTHERN STREAM TROUGH IS LIKELY TO PASS MORE PROGRESSIVELY... HARMLESSLY... AND LESS AMPLIFIED OFFSHORE AND THROUGH THE WESTERN ATLANTIC... SINCE THE LOW LEVEL THERMAL ADVECTION PATTERN ATTENDANT THE SURFACE WAVE WOULD BE ABSENT AND UNAVAILABLE TO FEED BACK AND AMPLIFY THE UPPER WAVE. THE OUTCOME OF THESE POSSIBLE SOLUTIONS WILL HAVE RAMIFICATIONS ON A POTENTIALLY WINDY DAY WEDNESDAY. REGARDING TEMPERATURES... MONDAY NIGHT SHOULD BE MUCH MILDER THAN THOSE OF RECENT DAYS... AS MID AND HIGH LEVEL CLOUDS THICKEN FROM THE SOUTHWEST AND EASTERLY FLOW DRAWS MILDER AND MOISTER AIR INTO THE REGION FROM THE ATLANTIC. LOWS 52 TO 58. HIGH TEMPERATURES TUESDAY 63 WEST TO AROUND 70 EAST WITH FURTHER THICKENING AND LOWERING CLOUD COVER AND INCREASING CHANCE OF RAIN FROM THE SOUTHWEST THROUGH THE DAY... THOUGH IF THE WET TREND CONTINUES THESE MAY BE OPTIMISTIC (PARTICULARLY WHERE RAIN ARRIVES FIRST IN THE WEST AND SOUTHWEST). && .LONG TERM /WEDNESDAY THROUGH SATURDAY/... AS OF 230 AM SUNDAY... DUE TO SOME CONVERGENCE IN THE MODELS SOLUTION IN BRINGING AN INFLUX OF DEEP TROPICAL MOISTURE NNE ACROSS THE SOUTHEAST INTO THE MID ATLANTIC STATES TUESDAY INTO EARLY WEDNESDAY... WE WILL HIGHLIGHT THE HIGHEST PROBABILITY OF RAIN (POTENTIALLY MODERATE TO HEAVY) WOULD OCCUR TUESDAY INTO EARLY WEDNESDAY. THE NORTHERN STREAM THEN TAKES OVER AT OUR LATITUDE. THIS WOULD RAPIDLY SHUNT THE FEED OF DEEP TROPICAL MOISTURE EASTWARD AND OFFSHORE WEDNESDAY AS OUR FLOW BECOMES WNW ALOFT. EVEN IF THE INTERACTION OF THE POLAR AND SUBTROPICAL FEATURES OFF THE NC/VA COAST OCCURS AS THE GFS/CANADIAN/ECMWF SUGGEST LATE WEDNESDAY INTO THURSDAY... THE MAIN AFFECTS THIS FAR INLAND WOULD BE GUSTY NNE WINDS AND DRYING CONDITIONS LATE WEDNESDAY INTO THURSDAY. WE WILL CONTINUE TO SHOW A DRYING TREND WEDNESDAY AFTERNOON INTO WEDNESDAY NIGHT... AND DRY COOL WEATHER FOR THURSDAY INTO FRIDAY. && .AVIATION /06Z SUNDAY THROUGH FRIDAY/... AS OF 1250 AM SUNDAY... VFR CONDITIONS ARE FORECAST THROUGH 06Z/MONDAY. HIGH PRESSURE WILL REMAIN OVER THE REGION THROUGH THE TAF PERIOD BRINGING LIGHT WINDS AND FAIR SKIES. THESE VFR CONDITIONS ARE EXPECTED THROUGH MONDAY... WITH AN INCREASE IN MID AND HIGH CLOUDINESS FROM THE SW DURING MONDAY... WITH CEILINGS REMAINING IN AT OR ABOVE 10K FEET THROUGH MONDAY. THE COMBINATION OF MOISTURE ASSOCIATED WITH TROPICAL STORM IDA AND A COLD FRONT APPROACHING THE AREA FROM THE NORTHWEST COULD RESULT IN IFR TO LIFR CEILINGS WITH WIDESPREAD RAIN TUESDAY AND TUESDAY NIGHT. VFR CONDITIONS ARE EXPECTED TO RETURN TO THE AREA ON WEDNESDAY AS DRY HIGH PRESSURE BUILDS TOWARD THE AREA BEHIND THE FRONT. && .RAH WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...BADGETT NEAR TERM...MWS SHORT TERM...MWS LONG TERM...BADGETT AVIATION...BADGETT/VINCENT