AREA FORECAST DISCUSSION
NWS TWIN CITIES/CHANHASSEN MN
AFDMSP 300 PM CST SUN FEB 17 2002
FORECAST FILLED WITH POTENTIAL PROBLEMS...WITH TEMPS MON...AND THEN
P-TYPE ON TUES/NIGHT. WILL LEAN ON ETA THIS CYCLE...GIVEN ITS
ACCURACY WITH PVS STORMS THIS WINTER AND INCONSISTENCIES IN AVN
GUIDANCE...ESP IN THERMAL FIELDS. WISH THE KOAK SOUNDING WOULD HAVE
BEEN INGESTED IN MRNG RUNS...WITH UPR LOW MOVING RIGHT OVER AREA AT
12Z...BUT MODELS SEEM TO INITIALIZE OK...EXCEPT FOR JET OVER ERN PAC
GIVEN ACARS DATA THIS MORNING.
TONIGHT...STRONG WAA CONTINUING AS WEAK S/W ALOFT MOVES OVR CWA.
JUST SOME THINNING CI IN RESPONSE TO THIS. TIGHT GRADIENT IN WAKE OF
HI WL MOV ACROSS CWA...KEEPING WINDS UP...AND BLAYER MIXED. MINS
WELL ABOV NORMAL.
MON...TEMPS THE ISSUE. JUST SOME SCT-BKN CI AS WAA CONTINUES IN LOW
LEVELS. WHILE SFC WINDS WILL BE A TAD WEAKER TOMORROW...PLENTY OF
WARM/VERY DRY AIR OVER KS/NE/MO WILL ADVECT NORTHWARD ON
STRENGTHENING H9-H8 FLOW. SFC TRAJECTORIES SHOW OUR SOURCE REGION
TOMORROW TO BE FROM KS/MO WHERE TEMPS TDY IN 50S AND 60S. WITH NO
SNOW AND TEMPS THE WAY THEY HAVE BEEN LATELY...WILL SOAR THEM WAY
ABOVE GUIDANCE PER ETA THICKNESS/THERMAL FIEDLS. DESPITE MDLS
WANTING TO SATURATE AND PRECIPITATE IN THE AFTN...THINGS WILL TAKE A
WHILE TO SATURATE PER AMOUNT OF DRY AIR IN MRNING RAOBS.
REST OF SHORT TERM...FIRST OF TWO JET MAX TO LIFT OUT MON NIGHT INTO
CNTL PLAINS. ASSOCD LEAD S/W IDUCING LEE CYCLOGENESIS IN ERN
CO...WHILE GULF OPENS WIDE ON STRONG LL FLOW. STRONG MOIST ADVEC TO
INCREASE PWATS TO 0.75" OVER ALL OF CWA. UPR DIVERGENCE OVER
CWA...COINCIDENT WITH MDL MID LEVEL UVV'S TO CAUSE NICE BAND OF RA
TO BREAK OUT MONDAY NIGHT AND SWEEP NORTH ON LOW LEVEL JET. MAIN S/W
AND UPR JET ENERGY TO ROUND BASE OF TROUGH ON TUESDAY...CAUSING
DEEPENING/SLOWING LOW...AND CONTINUED STRONG WAA/MOISTURE ADVECTION.
BANDS OF RAIN TO CONTINUE TO DEVELOP...AS ETA HINTING AT DEVELOPING
DEFORMATION ZONE FROM KRWF TO RICE LAKE. NRN FRINGE OF LARGE -RA
SHIELD TO MIX/CHANGE TO SNOW AS PERSISTENT UVV'S AND HEIGHT FALLS
ALLOW CRITICAL THICKNESSES TO FALL. WHILE TRANSITION ZONE LIKELY TO
BE NARROW...AM CONCERNED THAT SLOW MOVEMENT OF STORM AND COPIUS
MOISTURE COULD LEAD TO A NARROW BAND OF +SN. PER 84 HOUR ETA...H5
ENERGY FROM NORTHERN STREAM TO FALL IN UPR TROF...SLOWING SFC LOW
AND CAUSING CONTINUED DEFORMATION ACTIVITY AND SFC LOW DEEPENING.
GREAT UNCERTAINTY GIVEN LACK OF ARCTIC AIR...AND WIDELY DIFFERENT
STORM TRACKS...BUT GENERAL CONSENSUS OF FCST TRACKS SHOULD CHANGE NW
3/4 OF CWA TO SNOW BY 06Z WED. WL NOT ISSUE OUTLOOK AT THIS TIME
GIVEN THESE UNCERTANTIES. BUT WORD ZONES TO MENTION PSBL
ACCUMULATIONS ON TUE IN WEST/NORTH...AND MSP AREA TUE NIGHT.
CONTINUED LIGHTER SNOWS ON WED IN CYCLONIC FLOW.
.MSP...NONE
BINAU