FXUS63 KDDC 230931
AFDDDC
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DODGE CITY KS
331 AM CST WED DEC 23 2009
.DISCUSSION...
DAYS 1-2...
EVEN AT THIS LATE HOURLY LEADING UP TO THE EVENT...STILL MANY
QUESTIONS...PARTICULARLY AROUND SNOWFALL AMOUNTS AND WHERE
HEAVIEST SNOW WILL FALL. BY IN LARGE...THIS SYSTEM APPEARS TO BE
TURNING INTO A BIG DUD FOR SOUTHWEST KANSAS...FROM A SNOW
STANDPOINT. THE FREEZING DRIZZLE/FREEZING RAIN EVENT SINCE LATE
LAST NIGHT HAS BEEN THE MAIN HAZARD UP TO THIS POINT...AND ROADS
HAVE BECOME SLICK AND HAZARDOUS AREAWIDE. THE WIND AND SNOW...MOST
LIKELY LIGHT SNOW...WILL BE THE SECOND PHASE OF THIS EVENT...LATER
ON TODAY, TONIGHT, AND INTO THE FIRST PART OF THURSDAY.
WATER VAPOR LOOP SHOWED THE CYCLONE CLOSING OFF ALONG THE AZ/NM
BORDER AS OF 09Z. WILL FOLLOW THE BROAD H7 LOW CENTER AND H7 RH>90
PERCENT FIELDS FOR WHERE SNOW WILL TRACK. FRONTOGENESIS FORCING IS
HARD TO FIND AT H7, SO AM NOT EXPECTING ANY HEAVY PRECIPITATION
FOR THE REMAINDER OF THE EVENT...JUST A LARGE SPATIAL AREA OF LOW
ACCUMULATION RATE SNOW NEAR THE H7 VORT AXIS AS IT TRACKS ACROSS
SOUTHWEST KANSAS. THE 06Z NAM DOES HINT AT SMALL PV ANOMALY
EJECTING NORTHEAST INTO NORTHWEST OKLAHOMA AND SOUTH CENTRAL KS BY
THIS EVENING WHICH MAY HELP BOOST PRECIPITATION RATES...BUT IT IS
REALLY THE ONLY MODEL SHOWING THIS. THAT BEING SAID...ANY HINT AT
H7 CONVERGENCE NEAR THE H7 LOW WILL PROMOTE INCREASED
FRONTOGENESIS AND SUBSEQUENT SNOWFALL RATES...BUT THIS IS GOING TO
BE DIFFICULT TO ACHIEVE SINCE IT NOW APPEARS THAT THE MAJOR MID
LEVEL PV ANOMALY WILL BE TRACKING WELL TO THE SOUTH INTO NORTH
TEXAS...THEN LIFTING NORTH-NORTHEAST ACROSS THE OZARKS.
MEANWHILE...THE MONTANA/WYOMING VORT WILL MOVE SOUTH-
SOUTHEAST...WHICH WILL INFLUENCE THE TRACK OF THE SOUTHERN
VORT...WHILE SOUTHWEST KANSAS REMAINS IN BETWEEN THE TWO. FOR SNOW
AMOUNTS...AM JUST GOING TO GO WITH A GENERAL 2 TO 4 INCH FORECAST
ACROSS THE WHOLE AREA...BUT IF THE 06Z NAM12 IS ON TO SOMETHING
REGARDING THE MESOSCALE DETAILS...THEN SOME HIGHER AMOUNTS WILL BE
SEEN ACROSS THE EASTERN FA.
WE WILL NOT MISS OUT ON THE WIND. THANKS TO THE NORTHERN
VORT...SURFACE ANTICYCLOGENESIS WILL BE VERY GOOD ACROSS NORTHERN
MONTANA WITH 1036MB HIGH. THE SOUTHERN STREAM WAVE WILL PROVIDE
THE GREAT LOWER TROPOSPHERIC CYCLONIC RESPONSE WITH A DEEPENING
SUB 995MB LOW ACROSS THE OZARKS. IN BETWEEN...THE GRADIENT WILL BE
VERY STRONG...AND THESE WINDS ARE EXPECTED TO COMMENCE LATE
THURSDAY NIGHT...STRONGEST OCCURRING MIDDAY THURSDAY. EVEN WITH
JUST AN INCH OF ADDITIONAL SNOWFALL THURSDAY...BLIZZARD OR NEAR
BLIZZARD CONDITIONS WILL BE QUITE POSSIBLE AS SUSTAINED WINDS WILL
LIKELY REACH 30 TO 35 KNOTS AT TIMES...WITH GUSTS WELL INTO THE 40
TO PERHAPS 50 KNOT RANGE DURING THE HEIGHT OF THE WIND EVENT.
FRESH, NON-COMPACTED SNOWFALL WILL WHIP AROUND SUBSTANTIALLY
CAUSING PERHAPS SEVERE BLOWING AND DRIFTING WITH JUST ONE INCH OF
ACCUMULATION. EVEN IF LITTLE ADDITIONAL SNOW FALLS DURING THE WIND
EVENT THURSDAY...GROUND BLIZZARD CONDITIONS WILL BE POSSIBLE IN
THE AREAS THAT SEE 3 OR MORE INCHES OF SNOW. THIS IS THE REASONING
FOR CONTINUING WITH THE BLIZZARD WATCH...WITH ONE MORE SHIFT TO
RE-EVALUATE BEFORE UPGRADING TO A BLIZZARD WARNING FOR PORTIONS OF
THE DDC FA OR DROPPING THE WATCH IF THE SNOW DOES NOT MATERIALIZE.
-UMSCHEID
DAYS 3-7...
STRONG COLD ADVECTION WILL LEAD TO CONTINUED BREEZY, COLD WEATHER
CHRISTMAS DAY THROUGH THE WEEKEND. WINDS WILL BE STRONGEST ON FRI
AND THEN DECREASE THROUGH THE WEEKEND AS THE HUGE UPPER STORM
GRADUALLY WOBBLES FROM THE UPPER MISS RIVER VALLEY INTO THE GREAT
LAKES REGION OVER THE WEEKEND. AM KEEPING SLIGHT CHANCE POPS FOR FRI
MORNING AS MODELS STILL HINT AT SOME WEAK WRAP-AROUND BUT IN GENERAL
THE EXTENDED FORECAST FEATURES DRY WEATHER WITH DECREASING
CLOUDINESS. TEMPS WILL BE SOMEWHAT DIFFICULT AS THE MODIFIED ARCTIC
AIRMASS WILL BE SLOW TO MOVE. 2M TEMPS FROM THE EC FOR EXAMPLE
SUGGEST TEMPS STRUGGLING TO GET OUT OF THE 20S THROUGH THE WEEKEND.
WILL KEEP THE FORECAST AS IS BUT OUR HIGHS MAY BE TOO HIGH DEPENDING
ON THE STRENGTH OF COLD ADVECTION AND RESISTANCE TO MODERATION. THE
EC CONTINUES TO HINT AT A POSSIBLE PRECIP EVENT FOR THE CENTRAL
PLAINS BY TUE/WED OF NEXT WEEK AS ANOTHER SYSTEM COMES OUT OF THE SW
CONUS. THE GFS MOVES THE SYSTEM BY TO OUR SOUTH. WILL KEEP THE DRY
FORECAST FOR NOW, BUT THIS BEARS WATCHING. -WRIGHT
&&
.AVIATION...
COLD, UPSLOPE LOW LEVEL FLOW COMBINED WITH WARMER (ABV 0C) SOUTHERLY
MID LEVEL FLOW AHEAD OF A STRONG STORM EJECTING OUT OF THE SW U.S.
WILL KEEP OCNL FREEZING RAIN/SLEET GOING AT ALL TERMINALS THROUGH
THE MORNING. LATEST MODEL SOUNDINGS SHOW THE MID LEVEL WARM LAYER
GRADUALLY COOLING THROUGH 23/18Z AFTER WHICH PRECIP WILL CHANGE OVER
TO SNOW. THE UPPER LEVEL SYSTEM WILL MOVE RIGHT OHD BY 24/00Z WITH
PERIODS OF -SN (PERHAPS A BURST OF SN/+SN) AT ALL TERMINALS. STRONG
N/NW WINDS WILL SET IN AT ALL TERMINALS BY THU AM WITH CONTINUED CHC
OF -SN/BLSN. -WRIGHT
&&
.PRELIMINARY POINT TEMPS/POPS...
DDC 28 22 22 8 / 90 90 60 30
GCK 28 20 21 6 / 100 90 60 30
EHA 30 21 22 11 / 100 90 50 10
LBL 30 22 22 11 / 90 90 50 20
HYS 28 21 22 7 / 100 90 70 50
P28 32 26 26 11 / 90 90 60 30
&&
.DDC WATCHES/WARNINGS/ADVISORIES...
WINTER WEATHER ADVISORY UNTIL 6 PM CST /5 PM MST/ THIS EVENING
FOR KSZ030-031-043>046-061>066-074>081-084>088.
BLIZZARD WATCH FROM THIS EVENING THROUGH THURSDAY AFTERNOON FOR
KSZ030-031-043>046-061>066-074>081-084>090.
&&
$$
FN25/34/34
